FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Kalnay, E Park, SK Pu, ZX Gao, JD AF Kalnay, E Park, SK Pu, ZX Gao, JD TI Application of the quasi-inverse method to data assimilation SO MONTHLY WEATHER REVIEW LA English DT Article ID VARIATIONAL ASSIMILATION; FORECAST SENSITIVITY; INITIAL CONDITIONS; PREDICTION; SYSTEMS; ERRORS AB Four-dimensional variational data assimilation (4D-Var) seeks to find an optimal initial field that minimizes a cost function defined as the squared distance between model solutions and observations within an assimilation window. For a perfect linear model. Lorenc showed that the 4D-Var forecast at the end of the window coincides with a Kalman filter analysis if two conditions are fulfilled: (a) addition to the cost function of a term that measures the distance to the background at the beginning of the assimilation window, and (b) use of the Kalman filter background error covariance in this term. The standard 4D-Var requires minimization algorithms along with adjoint models to compute gradient information needed for the minimization. In this study, an alternative method is suggested based on the use of the quasi-inverse model that, for certain applications, may help accelerate the solution of problems close to 4D-Var. The quasi-inverse approach for the forecast sensitivity problem is introduced, and then a closely related variational assimilation problem using the quasi-inverse model is formulated (i.e., the model is integrated back ward but changing the sign of the dissipation terms). It is shown that if the cost Function has no background term, and has a complete set of observations (as assumed in many classical 4D-Var papers), the new method solves the 4D-Var-minimization problem efficiently, and is in fact equivalent to the Newton algorithm but without having to compute a Hessian. If the background term is included but computed at the end of the interval, allowing the use of observations that are not complete, the minimization can still be carried out very efficiently. In this case, however the method is much closer to a 3D-Var formulation in which the analysis is attained through a model integration. For this reason, the method is called "inverse 3D-Var" (I3D-Var). The I3D-Var method was applied to simple models (viscous Purgers' equation and Lorcnz model), and it was Found that when the background term is ignored and complete fields of noisy observations are available at multiple times, the inverse 3D-Var method minimizes the same cost function as 4D-Var but converges much faster. Tests with the Advanced Regional Prediction System (ARPS) indicate that I3D-Var is about twice as fast as the adjoint Newton method and many times faster than the quasi-Newton LBFGS algorithm, which uses the adjoint model. Potential problems (including the growth of random errors during the integration back in time) and possible applications to preconditioning, and to problems such as storm-scale data assimilation and reanalysis are also discussed. C1 Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Univ Oklahoma, Sch Meteorol, Cooperat Inst Mesoscale Meteorol Studies, Norman, OK 73019 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Oklahoma, Ctr Anal & Predict Storms, Norman, OK 73019 USA. RP Park, SK (reprint author), Univ Maryland, Dept Meteorol, 3431 Comp & Space Sci Bldg, College Pk, MD 20742 USA. RI Kalnay, Eugenia/F-4393-2010; OI Kalnay, Eugenia/0000-0002-9984-9906 NR 34 TC 19 Z9 21 U1 1 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAR PY 2000 VL 128 IS 3 BP 864 EP 875 DI 10.1175/1520-0493(2000)128<0864:AOTQIM>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307AZ UT WOS:000086632400019 ER PT J AU Doyle, JD Durran, DR Chen, C Colle, BA Georgelin, M Grubisic, V Hsu, WR Huang, CY Landau, D Lin, YL Poulos, GS Sun, WY Weber, DB Wurtele, MG Xue, M AF Doyle, JD Durran, DR Chen, C Colle, BA Georgelin, M Grubisic, V Hsu, WR Huang, CY Landau, D Lin, YL Poulos, GS Sun, WY Weber, DB Wurtele, MG Xue, M TI An intercomparison of model-predicted wave breaking for the 11 January 1972 Boulder windstorm SO MONTHLY WEATHER REVIEW LA English DT Article ID SEVERE DOWNSLOPE WINDSTORM; AMPLITUDE MOUNTAIN WAVES; PAST ISOLATED TOPOGRAPHY; 3 SPATIAL DIMENSIONS; GRAVITY-WAVES; POTENTIAL VORTICITY; SIMULATION; FLOW; TURBULENCE; EVOLUTION AB Two-dimensional simulations of the 11 January 1972 Boulder, Colorado, windstorm, obtained from 11 diverse nonhydrostatic models, are intercompared with special emphasis on the turbulent breakdown of topographically forced gravity waves, as part of the preparation for the Mesoscale Alpine Programme field phase. The sounding used to initialize the models is more representative of the actual lower stratosphere than those applied in previous simulations. Upper-level breaking is predicted by all models in comparable horizontal locations and vertical layers, which suggests that gravity wave breaking may be quite predictable in some circumstances. Characteristics of the breaking include the following: pronounced turbulence in the 13-16-km and 18-20-km layers positioned beneath a critical level near 21-km, a well-defined upstream tilt with height, and enhancement of upper-level breaking superpositioned above the low-level hydraulic jump. Sensitivity experiments indicate that the structure of the wave bi caking was impacted by the numerical dissipation, numerical representation of the horizontal advection, and lateral boundary conditions. Small vertical wavelength variations in the shear and stability above 10 km contributed to significant changes in the structures associated with wave breaking. Simulation of this case is ideal for testing and evaluation of mesoscale numerical models and numerical algorithms because of the complex wave-breaking response. C1 USN, Res Lab, Marine Meteorol Div, Monterey, CA 93943 USA. Univ Washington, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Toulouse 3, Lab Aerol, F-31062 Toulouse, France. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Natl Taiwan Univ, Taipei 10764, Taiwan. Natl Cent Univ, Taipei, Taiwan. Univ Calif Los Angeles, Los Angeles, CA USA. N Carolina State Univ, Raleigh, NC 27695 USA. Colorado Res Assoc, Boulder, CO USA. Purdue Univ, W Lafayette, IN 47907 USA. Univ Oklahoma, CAPS, Norman, OK 73019 USA. RP Doyle, JD (reprint author), USN, Res Lab, Marine Meteorol Div, 7 Grace Hopper Ave, Monterey, CA 93943 USA. EM doyle@nrlmry.navy.mil RI Xue, Ming/F-8073-2011; Durran, Dale/G-3677-2015 OI Xue, Ming/0000-0003-1976-3238; Durran, Dale/0000-0002-6390-2584 NR 42 TC 74 Z9 74 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAR PY 2000 VL 128 IS 3 BP 901 EP 914 DI 10.1175/1520-0493(2000)128<0901:AIOMPW>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 307AZ UT WOS:000086632400023 ER PT J AU Ciocan, R Petulescu, P Ciobanu, D Roth, DJ AF Ciocan, R Petulescu, P Ciobanu, D Roth, DJ TI The use of the neural networks in the recognition of the austenitic steel types SO NDT & E INTERNATIONAL LA English DT Article DE ultrasonics; neural network; spectral analysis; austenitic steels AB The work shows the results obtained in recognition of different types of austenitic steels with an ultrasonic system that provides the necessary data towards two different neural networks. One of the neural networks (RNAU) used as input a vector containing processed data (propagation velocity and ultrasonic attenuation). The second neural network (AUFRAN) used the amplitude of digitized radio-frequency signal and its numerical Fourier transform as input vector, Two thirds of data obtained from three kinds of steels (W.1.4541, W.1.6903 and HP50) were used in the learning process. The last third of acquired data on these samples were used in the testing process, The obtained classification probabilities were above 98.3%. As a supplement, the testing process was extended to three other types of austenitic steels having different chemical compositions than those used in the learning process, (C) 2000 Elsevier Science Ltd, All rights reserved. C1 Case Western Reserve Univ, Dept Elect Engn & Comp Sci, Cleveland, OH 44106 USA. Ovidius Univ, Constanta 8700, Romania. Inst Nucl Res, Pitesti 0300, Romania. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Ciocan, R (reprint author), Case Western Reserve Univ, Dept Elect Engn & Comp Sci, Cleveland, OH 44106 USA. NR 7 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0963-8695 J9 NDT&E INT JI NDT E Int. PD MAR PY 2000 VL 33 IS 2 BP 85 EP 89 DI 10.1016/S0963-8695(99)00032-8 PG 5 WC Materials Science, Characterization & Testing SC Materials Science GA 274ZR UT WOS:000084795400003 ER PT J AU He, Z Li, W Knoll, GF Wehe, DK Stahle, CM AF He, Z Li, W Knoll, GF Wehe, DK Stahle, CM TI Measurement of material uniformity using 3-D position sensitive CdZnTe gamma-ray spectrometers SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article DE gamma-ray spectrometers; semiconductor; CdZnTe; position sensitive gamma-ray detectors ID DETECTORS AB We present results from two 1 cm(3) CdZnTe gamma-ray spectrometers with full 3-D position sensitivity. To our knowledge, these are the first reported semiconductor spectrometers that provide independent spectral data for each of over 2000 volume elements. Energy resolutions of 1.5-1.6% FWHM and position resolutions of 0.7 x 0.7 x 0.5 mm were obtained at 662 keV gamma-ray energy from the central region of both detectors for single-pixel events. With the 3-D position sensing capability variations in spectral response over the detector volume were recorded using a Cs-137 source. These measurements allow a study of full-energy peak efficiency, mean ionization energy and electron trapping as a function of 3-D position. The effects of material non-uniformity on detector spectroscopic performance are discussed. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Michigan, Dept Nucl Engn & Radiol Sci, Ann Arbor, MI 48109 USA. NASA, Goddard Space Flight Ctr, Detector Syst Branch, Greenbelt, MD 20771 USA. RP He, Z (reprint author), Univ Michigan, Dept Nucl Engn & Radiol Sci, Ann Arbor, MI 48109 USA. RI Chang, Yong/B-3541-2009 NR 6 TC 11 Z9 11 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD MAR 1 PY 2000 VL 441 IS 3 BP 459 EP 467 DI 10.1016/S0168-9002(99)00860-8 PG 9 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 295JH UT WOS:000085962600015 ER PT J AU Sarkisov, SS Curley, MJ Diggs, DE Wilkosz, A Grimalsky, VV Adamovsky, G AF Sarkisov, SS Curley, MJ Diggs, DE Wilkosz, A Grimalsky, VV Adamovsky, G TI Dark spatial solitons in photopolymer films for optical interconnections SO OPTICAL ENGINEERING LA English DT Article DE optical interconnections; dark spatial soliton; photobleaching; frequency up-converted emission; polymer optical waveguide; light-induced waveguide ID WAVE-GUIDES; BEAMS; DYE AB We demonstrate theoretically and experimentally that an initially Gaussian red light beam sent through a pi-step phase mask and launched into a thin film of polymer poly(methyl methacrylate) doped with laser dye 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)4H-pyran known as DCM evolves into a spatial structure similar to a dark spatial soliton. This takes place due to the Kerr-type time-delayed nonlinearity associated with the mechanism of up-converted photobleaching of the dye-doped polymer. The proposed theoretical model is nonlocal in time and is based on the Shrodinger-type nonlinear equation for the amplitude of the propagating beam complemented by the rate equation for the light-induced decrease of the refractive index. The result of the structuring of the beam is the formation of a permanent pattern of the refractive index of the film that acts as a channel waveguide, trapping a weak Gaussian probe beam close to it. The probe beam can propagate along or against the soliton. We also demonstrate the tolerance of trapping to a possible shift or tilt of the probe beam with respect to the soliton. This makes the proposed approach potentially useful for interconnections between individual fibers, fiber ribbons. bundles, and multicore fibers as well as between fibers and planar integrated optical devices, a 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)00103-3]. C1 Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. Nichols Res Corp, Huntsville, AL 35802 USA. Natl Acad Sci Ukraine, Space Res Inst, Natl Space Agcy Ukraine, UA-252022 Kiev, Ukraine. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Sarkisov, SS (reprint author), Alabama A&M Univ, Dept Phys, 4900 Meridan St,POB 1268, Normal, AL 35762 USA. NR 14 TC 4 Z9 4 U1 1 U2 3 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD MAR PY 2000 VL 39 IS 3 BP 616 EP 623 DI 10.1117/1.602406 PG 8 WC Optics SC Optics GA 294LQ UT WOS:000085913100006 ER PT J AU Mouroulis, P McKerns, MM AF Mouroulis, P McKerns, MM TI Pushbroom imaging spectrometer with high spectroscopic data fidelity: experimental demonstration SO OPTICAL ENGINEERING LA English DT Article DE optical design; imaging spectroscopy; hyperspectral imaging; remote sensing; distortion; spectral calibration AB Experimental results are described from a pushbroom imaging spectrometer module demonstrating very low spectral and spatial distortion (a few percent of a pixel) and similarly small variation in spectral response function with field position. These spectrometer properties significantly facilitate the extraction of accurate spectroscopic information. The spectrometer can achieve high performance despite relaxed tolerances in fabrication and alignment. A quick and effective alignment method is described that permits the spectrometer to approximate ifs design performance. The implications of the results for the calibration techniques of pushbroom imaging spectrometers are also discussed. (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)03103-2]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mouroulis, P (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 16 TC 44 Z9 47 U1 1 U2 6 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD MAR PY 2000 VL 39 IS 3 BP 808 EP 816 DI 10.1117/1.602431 PG 9 WC Optics SC Optics GA 294LQ UT WOS:000085913100032 ER PT J AU Bessis, D Temkin, A AF Bessis, D Temkin, A TI Partial-wave dispersion relations: Exact left-hand E-plane discontinuity computed from the Born series SO PHYSICAL REVIEW A LA English DT Article AB We show that for a superposition of Yukawa potentials, the exact left-hand cut discontinuity in the complex-energy plane of the (S-wave) scattering amplitude is given, in an interval depending on n, by the discontinuity of the Born series stopped at order n. This establishes an inverse and unexpected correspondence of the Born series at positive high energies and negative low energies. With the discontinuity on the left-hand axis elucidated, we can construct a viable dispersion relation (DR) for the partial (S-) wave amplitude. The DR is numerically verified for the exponential potential at zero scattering energy. Generalization to higher partial waves, and extension of these ideas to field theory are discussed. C1 Clark Atlanta Univ, Ctr Theoret Studies Phys Syst, Atlanta, GA 30314 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Bessis, D (reprint author), Clark Atlanta Univ, Ctr Theoret Studies Phys Syst, Atlanta, GA 30314 USA. NR 11 TC 4 Z9 4 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAR PY 2000 VL 61 IS 3 BP art. no. EP 032702 PG 3 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 293DM UT WOS:000085836300045 ER PT J AU Bhatia, AK Drachman, RJ AF Bhatia, AK Drachman, RJ TI Static properties and the Stark effect of the ground state of the HD molecular ion SO PHYSICAL REVIEW A LA English DT Article ID RYDBERG LEVELS; POLARIZABILITIES; LITHIUM; HELIUM; H-2(+) AB We have calculated the static properties;of the ground state of the HD+ ion and its lowest-lying P state without making use of the Born-Oppenheimer approximation, as was done in the case of H-2(+) and D-2(+) [A. K. Bhatia, Phys. Rev. A 58, 2787 (1998)]. The ion is treated as a three-body system whose ground state is spherically symmetric. The wave function is of generalized Hylleraas type, but it is necessary to include high powers of the internuclear distance to localize the nuclear motion. We obtain good values of the energies of the ground S state and lowest P state and compare them with earlier calculations. Expectation values are obtained for various operators, the Fermi contact parameters, and the permanent quadrupole moment. The cusp conditions are also calculated. The polarizability is then calculated using second-order perturbation theory with intermediate P pseudostates. Since the nuclei in HD+ are not of equal mass there is dipole coupling between the lowest two rotational states, which are almost degenerate. This situation is carefully analyzed, and the Stark shift is calculated variationally as a function of the applied electric field. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NR 17 TC 12 Z9 12 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9926 EI 2469-9934 J9 PHYS REV A JI Phys. Rev. A PD MAR PY 2000 VL 61 IS 3 AR 032503 DI 10.1103/PhysRevA.61.032503 PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 293DM UT WOS:000085836300039 ER PT J AU Cerf, NJ Grover, LK Williams, CP AF Cerf, NJ Grover, LK Williams, CP TI Nested quantum search and structured problems SO PHYSICAL REVIEW A LA English DT Article ID COMPUTERS AB A quantum algorithm is known that solves an unstructured search problem in a number of iterations of order root d, where d is the dimension of the search space, whereas any classical algorithm necessarily scales as O(d). It is shown here that an improved quantum search algorithm can be devised that exploits the structure of a tree search problem by nesting one quantum search within another. The average number of iterations required to find the solution of a typical hard instance of a constraint satisfaction problem is found to scale as root d(alpha), with the constant alpha<1 depending on the nesting depth and the type of problem considered. This corresponds to a square-root speedup over a classical nested search algorithm, of which our algorithm is the quantum counterpart. When applying a single nesting level to a problem with constraints of size 2 such as the graph coloring problem, alpha is estimated to be around 0.62. C1 CALTECH, WK Kellogg Radiat Lab, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Informat & Comp Technol Res Sect, Pasadena, CA 91109 USA. Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. Bell Labs, Murray Hill, NJ 07974 USA. RP CALTECH, WK Kellogg Radiat Lab, Pasadena, CA 91125 USA. NR 31 TC 25 Z9 26 U1 0 U2 1 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9926 EI 2469-9934 J9 PHYS REV A JI Phys. Rev. A PD MAR PY 2000 VL 61 IS 3 AR 032303 DI 10.1103/PhysRevA.61.032303 PG 14 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 293DM UT WOS:000085836300027 ER PT J AU Miller, RS Bellan, J AF Miller, RS Bellan, J TI Direct numerical simulation and subgrid analysis of a transitional droplet laden mixing layer SO PHYSICS OF FLUIDS LA English DT Article ID LARGE-EDDY SIMULATION; DISPERSED SOLID PARTICLES; HOMOGENEOUS TURBULENCE; PREFERENTIAL CONCENTRATION; ISOTROPIC TURBULENCE; 2-WAY INTERACTION; FLOWS; MODELS; EQUILIBRIUM; STATISTICS AB Direct numerical simulations of a temporally developing, droplet laden mixing layer undergoing transition to mixing turbulence are conducted. The formulation includes complete two-way couplings of mass, momentum, and energy. As many as 18 x 10(6) grid points are used to discretize the Eulerian gas phase equations and up to 5.7 x 10(6) initially polydisperse evaporating droplets are tracked in the Lagrangian reference frame. The complete transition to mixing turbulence is captured for several of the higher Reynolds number simulations and it is observed that increasing the droplet mass loading ratio results in a more "natural" turbulence characterized by increased rotational energy and less influence of the initial forcing perturbations. An increased mass loading also results in increased droplet organization within the layer. An a priori subgrid analysis is then conducted which shows that neglecting subgrid velocity fluctuations in the context of large eddy simulations may result in significant errors in predicting the droplet drag force for Stokes numbers St similar to 1 (with the flow time scale based on the mean velocity difference and initial vorticity thickness). Similar possible errors of lesser magnitude are also observed for the droplet heat flux and evaporation rate when thermodynamic subgrid fluctuations are neglected. An extension of the eddy interaction model commonly used in Reynolds-averaged simulations is then proposed in order to account for the missing subgrid information. Probability density functions (PDFs) of the subgrid fluctuations calculated across homogeneous planes are shown to be highly intermittent, particularly near the laminar-turbulent boundaries of the mixing layer. However, the actual subgrid PDFs calculated locally are much less intermittent and may be adequately modeled by the Gaussian distribution throughout the majority of the mixing layer. A scale similarity model is then employed to predict both the velocity and thermodynamic subgrid variances. The similarity model is well correlated with the actual subgrid variances and shows good agreement in predicting the local fluctuation intensities when a filter width-dependent model constant is used. The subgrid fluctuation variances acting on the droplets are then shown to be well modeled if the Eulerian subgrid variance model is interpolated to the droplet locations. (C) 2000 American Institute of Physics. [S1070-6631(00)02303-5]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Miller, RS (reprint author), Clemson Univ, Dept Mech Engn, Clemson, SC 29634 USA. NR 46 TC 53 Z9 53 U1 1 U2 8 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD MAR PY 2000 VL 12 IS 3 BP 650 EP 671 DI 10.1063/1.870271 PG 22 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 282VN UT WOS:000085241100020 ER PT J AU Rosen, PA Hensley, S Joughin, IR Li, FK Madsen, SN Rodriguez, E Goldstein, RM AF Rosen, PA Hensley, S Joughin, IR Li, FK Madsen, SN Rodriguez, E Goldstein, RM TI Synthetic aperture radar interferometry - Invited paper SO PROCEEDINGS OF THE IEEE LA English DT Review DE geophysical applications; interferometry; synthetic aperture radar (SAR) ID SIR-C/X-SAR; COSEISMIC DEFORMATION FIELD; GREENLAND ICE-SHEET; LANDERS EARTHQUAKE; CRUSTAL DEFORMATION; CALIFORNIA EARTHQUAKE; DISPLACEMENT-FIELDS; SEISMIC MIGRATION; GREECE EARTHQUAKE; EARTHS SURFACE AB Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. By exploiting the phase of the coherent radar signal, interferometry has transformed radar remote sensing from a largely interpretive science to a quantitative tool, with applications in cartography, geodesy, land cover characterization, and natural hazards. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Tech Univ Denmark, DK-2800 Lyngby, Denmark. RP Rosen, PA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Joughin, Ian/A-2998-2008 OI Joughin, Ian/0000-0001-6229-679X NR 188 TC 878 Z9 985 U1 16 U2 100 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9219 J9 P IEEE JI Proc. IEEE PD MAR PY 2000 VL 88 IS 3 BP 333 EP 382 DI 10.1109/5.838084 PG 50 WC Engineering, Electrical & Electronic SC Engineering GA 301VR UT WOS:000086331400004 ER PT J AU Granat, RA Na, H AF Granat, RA Na, H TI Estimating dynamic ionospheric changes without a priori models SO RADIO SCIENCE LA English DT Article ID TIME-VARYING RECONSTRUCTION; TOMOGRAPHY AB We present a novel artificial-neural-network-based computerized ionospheric tomography technique, capable of imaging through time in three-dimensional space. Total electron content (TEC) data collected from a satellite passing over the region of interest are used to train a neural network. The trained network creates estimates of the difference in ionospheric electron density between time steps based on the TEC data. Application of the difference estimate at each time step to the previous electron density image results in a time-varying ionospheric electron density estimate. Experimental results on synthetic data are presented that demonstrate that the algorithm is capable of detecting short-term localized disturbances in the ionosphere. C1 Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Granat, RA (reprint author), Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90095 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD MAR-APR PY 2000 VL 35 IS 2 BP 341 EP 349 DI 10.1029/1999RS900109 PG 9 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 298TV UT WOS:000086156000005 ER PT J AU Cummer, SA Inan, US AF Cummer, SA Inan, US TI Modeling ELF radio atmospheric propagation and extracting lightning currents from ELF observations SO RADIO SCIENCE LA English DT Article ID IONOSPHERE WAVE-GUIDE; WAVEGUIDE; FIELDS AB Observations of extremely low frequency (ELF) radio atmospherics (sferics), the transient electromagnetic fields radiated by lightning discharges, are used to determine the current moment waveforms of vertical lightning discharges. In order to extract this information the propagation of radio atmospherics from source to receiver must be modeled accurately, especially in view of the important role played by the D and E regions of the ionosphere at these long (>200 km) wavelengths. We model broadband ELF sferic waveforms by adapting a single-frequency ELF propagation code to calculate an ELF propagation impulse response under the assumption of horizontal ionospheric homogeneity, with which we extract the source lightning current waveform from an observed ELF sferic waveform using a deconvolution method based on linear regularization. Tests on modeled sferics indicate that the method is accurate and relatively insensitive to noise, and we demonstrate the application of the technique with a sprite-associated sferic. Since ELF sferics can often be observed many thousands of kilometers from the source discharge, the technique developed here represents a powerful new method of remotely sensing lightning current waveforms. C1 Stanford Univ, Space Telecommun & Radiosci Lab, Stanford, CA 94305 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Cummer, SA (reprint author), Duke Univ, Dept Elect & Comp Engn, Durham, NC 27708 USA. RI Cummer, Steven/A-6118-2008 OI Cummer, Steven/0000-0002-0002-0613 NR 34 TC 62 Z9 62 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD MAR-APR PY 2000 VL 35 IS 2 BP 385 EP 394 DI 10.1029/1999RS002184 PG 10 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 298TV UT WOS:000086156000009 ER PT J AU Marcucci, MG Polk, JE AF Marcucci, MG Polk, JE TI NSTAR xenon ion thruster on Deep Space 1: Ground and flight tests (invited) SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article; Proceedings Paper CT 8th International Conference on Ion Sources CY SEP 06-10, 1999 CL KYOTO, JAPAN AB After having been in development for many years at the Glenn Research Center (formerly the Lewis Research Center), the national aeronautics and space administration-designed, 30 cm, ring-cusp, xenon ion engine was launched on the Deep Space 1 (DS1) spacecraft on 24 Oct. 1998 from the Kennedy Space Center in Florida. It has since accumulated 2200 h of in-space thrusting at input power levels ranging from 0.52 to 1.96 kW, has successfully enabled the spacecraft to fly by the asteroid Braille in July 1999, and is now thrusting DS1 along a trajectory towards its comet destinations in 2001. The design, assembly, test, integration, and operation of this thruster comprise a unique path of technical determination, artful design choices, persistent engineering and analysis, and mastery of vacuum chamber operations. The testing program over the development years, the assembly and integration periods, and the flight operational period thus far have shown that the project test philosophy of segregating effects against unique causes proved itself most useful. The 8000 h life test, the culmination of the pre-launch ground test plan, not only met its goals but surpassed them with margin. This article will explain the thruster test program from beginning to end, illustrating the technical and programmatic decision making along the way. It will justify the use of engineering models as an inexpensive method of determining answers to key design questions and will explain why testing of the thruster alone only solved a portion of the system operations task. The highlight of the test program proved to be the vacuum firing of the ion engine during the spacecraft's solar thermal vacuum test. A comparison of the preflight data with postflight data shows that high confidence was warranted for executing a successful flight to the asteroid and beyond. (C) 2000 American Institute of Physics. [S0034-6748(00)51402-6]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Marcucci, MG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 6 Z9 6 U1 1 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAR PY 2000 VL 71 IS 3 BP 1389 EP 1400 DI 10.1063/1.1150468 PG 12 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 290QZ UT WOS:000085688600022 ER PT J AU Pepper, SV Wheeler, DR AF Pepper, SV Wheeler, DR TI Quantitative characterization of an x-ray source in an x-ray photoelectron spectroscopy system SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID SPECTRA; TUBES AB The x-ray spectrum from a dual anode x-ray source in an x-ray photoelectron spectroscopy system was calculated by the NIST Desk Top Spectrum Analyzer used for synthesizing spectra in energy dispersive x-ray analyzers commonly found in scanning electron microscopes. The energy flux was obtained by integrating over the x-ray energy spectrum. The energy flux from the source was measured by a silicon photodiode. Very good quantitative agreement was found between the flux obtained from the calculated spectra and the flux measured by the photodiode, indicating that the calculated spectra are, in fact, physically valid for this source. The calculated spectra were used to obtain the energy deposition as a function of depth below the irradiated surface of polytetrafluoro- ethylene, a material used in spacecraft and exposed to the space radiation environment. [S0034-6748(00)03703-5]. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Pepper, SV (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 9 TC 9 Z9 9 U1 1 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAR PY 2000 VL 71 IS 3 BP 1509 EP 1515 DI 10.1063/1.1150498 PG 7 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 290QZ UT WOS:000085688600044 ER PT J AU Goodman, DL Byrne, CA Yen, A Moulton, R Dixon, D Costen, RC AF Goodman, DL Byrne, CA Yen, A Moulton, R Dixon, D Costen, RC TI Automated tape placement with in-situ electron beam cure SO SAMPE JOURNAL LA English DT Article AB Automated tape placement (ATP) ia widely used in the aerospace industry to produce large composite structures with complex geometry. An innovative process combining ATP with in-situ electron beam (LB) curing has the potential to decrease composite part costs, especially for large integrated structures. A group consisting of Science Research Laboratory, Applied Poleramics and Northrop-Grumman is currently developing results, tape and electron gun technology for in-situ curing of ATP composites. ([1]) This paper presents mechanical and thermal properties for composite panels fabricated using a simulated in-sun EB cure process, with comparison to panels cured in a single step EB process. We can also present design tradeoffs for in-situ EB curing systems and describe how the choice of processing geometry affects the design. SRI has fabricated an in-situ EB curing system based on these design. The portable robotic EB gun will be combined with an existing ATP head at the NASA Marshall Space Flight Center for demonstration of the in-situ curing process later this year. C1 Northrop Grumman Corp, Los Angeles, CA 90067 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 12 TC 7 Z9 10 U1 0 U2 4 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 0091-1062 J9 SAMPE J JI Sampe J. PD MAR-APR PY 2000 VL 36 IS 2 BP 11 EP 17 PG 7 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 291BN UT WOS:000085713200006 ER PT J AU Oberg, J Aldrin, B AF Oberg, J Aldrin, B TI A bus between the planets SO SCIENTIFIC AMERICAN LA English DT Article C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. USAF, Test Pilot Sch, Edwards AFB, CA USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 USA SN 0036-8733 J9 SCI AM JI Sci.Am. PD MAR PY 2000 VL 282 IS 3 BP 58 EP 60 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 285WK UT WOS:000085411200025 PM 10736837 ER PT J AU Ruzmaikin, A AF Ruzmaikin, A TI Can we get the bottom B? SO SOLAR PHYSICS LA English DT Article ID SOLAR CONVECTION ZONE; LATITUDINAL DIFFERENTIAL ROTATION; EMERGING FLUX TUBES; MAGNETIC-FIELD; JOINT INSTABILITY; ACTIVE REGIONS; PATTERNS; DYNAMO; RINGS; CYCLE AB Understanding the solar dynamics and the origin of active regions depends crucially on our knowledge of the magnetic fields deep within the convection zone. Can we determine magnetic fields there? Some clues are given by dynamo theories and modeling of those instabilities in the convection zone which result in the emergence of magnetic flux. Magnetic field generated by dynamo is predominantly azimuthal and believed to be unstable to the formation of flux tubes. Simulations indicate that the emergence of the magnetic flux tubes strongly depends on the field strength and its longitudinal distribution at the bottom of the convection zone. In a unifying approach advocated in this paper the solar magnetic field is split into a mean part generated by the mean-field dynamo and a fluctuating part approximated by an ensemble of flux tubes. Observationally, the identification of the longitudinal distribution of emerging photospheric magnetic fields can give us information about the magnetic field strength at the bottom of the convection zone. Distinguishing between the modes of emerging field requires simultaneous magnetic imaging of both sides of the Sun. Correlation of simultaneous Dopplergrams of the photosphere from earthside and from the farside of the Sun opens an opportunity to detect velocity structures at the base of the convection zone, associated with the dynamo and emerging active regions. This global imaging of the photosphere can also be used for detection of a magnetic field in the solar core. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ruzmaikin, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM aruzmaikin@jplsp.jpl.nasa.gov NR 33 TC 5 Z9 5 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAR PY 2000 VL 192 IS 1-2 BP 49 EP 57 DI 10.1023/A:1005279201819 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335CQ UT WOS:000088224800004 ER PT J AU Kosovichev, AG Duvall, TL Scherrer, PH AF Kosovichev, AG Duvall, TL Scherrer, PH TI Time-distance inversion methods and results - (Invited review) SO SOLAR PHYSICS LA English DT Review ID HELIOSEISMOLOGY; TOMOGRAPHY; SUNSPOTS; SEISMOLOGY; INSTRUMENT AB The current interpretations of the travel-time measurements in quiet and active regions on the Sun are discussed. These interpretations are based on various approximations to the 3-D wave equation such as the Fermat principle for acoustic rays and the Born approximation. The ray approximation and its modifications have provided the first view of the 3-D structures and flows in the solar interior. However, more accurate and computationally efficient approximations describing the relation between the wave travel times and the internal properties are required to study the structures and flows in detail. Inversion of the large three-dimensional datasets is efficiently carried out by regularized iterative methods. Some results of time-distance inversions for emerging active regions, sunspots, meridional flows and supergranulation are presented. An active region which emerged on the solar disk in January 1998, was studied from SOHO/MDI for eight days, both before and after its emergence at the surface. The results show a complicated structure of the emerging region in the interior, and suggest that the emerging flux ropes travel very quickly through the depth range of our observations. The estimated speed of emergence is about 1.3 km s(-1). Tomographic images of a large sunspot reveal sunspot 'fingers' - long narrow structures at a depth of about 4 Mm, which connect the sunspot with surrounding pores of the same polarity. C1 Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Kosovichev, AG (reprint author), Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA. RI Duvall, Thomas/C-9998-2012 NR 24 TC 249 Z9 250 U1 1 U2 5 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAR PY 2000 VL 192 IS 1-2 BP 159 EP 176 DI 10.1023/A:1005251208431 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335CQ UT WOS:000088224800010 ER PT J AU Duvall, TL Gizon, L AF Duvall, TL Gizon, L TI Time-distance helioseismology with f modes as a method for measurement of near-surface flows SO SOLAR PHYSICS LA English DT Article ID SOLAR PHOTOSPHERE; ROTATION; FEATURES AB Travel times measured for the f mode have been used to study flows near the solar surface in conjunction with simultaneous measurements of the magnetic field. Previous flow measurements of Doppler surface rotation, small magnetic feature rotation, supergranular pattern rotation, and surface meridional circulation have been confirmed. In addition, the flow in supergranules due to Coriolis forces has been measured. The spatial and temporal power spectra for a six-day observing sequence have been measured. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA. RP NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RI Gizon, Laurent/B-9457-2008; Duvall, Thomas/C-9998-2012 NR 25 TC 112 Z9 112 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 EI 1573-093X J9 SOL PHYS JI Sol. Phys. PD MAR PY 2000 VL 192 IS 1-2 BP 177 EP 191 DI 10.1023/A:1005239503637 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335CQ UT WOS:000088224800011 ER PT J AU De Rosa, M Duvall, TL Toomre, J AF De Rosa, M Duvall, TL Toomre, J TI Near-surface flow fields deduced using correlation tracking and time-distance analyses SO SOLAR PHYSICS LA English DT Article ID HELIOSEISMOLOGY AB Near-photospheric flow fields on the Sun are deduced using two independent methods applied to the same time series of velocity images observed by SOI-MDI on SOHO. Differences in travel times between f modes entering and leaving each pixel measured using time-distance helioseismology are used to determine sites of supergranular outflows. Alternatively, correlation tracking analysis of mesogranular scales of motion applied to the same time series is used to deduce the near-surface flow field. These two approaches provide the means to assess the patterns and evolution of horizontal flows on supergranular scales even near disk center, which is not feasible with direct line-of-sight Doppler measurements. We find that the locations of the supergranular outflows seen in flow fields generated from correlation tracking coincide well with the locations of the outflows determined from the time-distance analysis, with a mean correlation coefficient after smoothing of (r) over bar(s)=0.890. Near-surface velocity field measurements can be used to study the evolution of the supergranular network, as merging and splitting events are observed to occur in these images. The data consist of one 2048-min time series of high-resolution (0.6'' pixels) line-of-sight velocity images taken by MDI on 1997 January 16 -18 at a cadence of one minute. C1 Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP De Rosa, M (reprint author), Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. RI Duvall, Thomas/C-9998-2012 NR 7 TC 19 Z9 19 U1 1 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAR PY 2000 VL 192 IS 1-2 BP 351 EP 361 DI 10.1023/A:1005269001739 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 335CQ UT WOS:000088224800023 ER PT J AU Tokarev, YV Kaiser, ML Belov, YI Boiko, GN Murav'eva, NV AF Tokarev, YV Kaiser, ML Belov, YI Boiko, GN Murav'eva, NV TI Small-scale turbulence of the solar wind in the vicinity of the earth's shock wave SO SOLAR SYSTEM RESEARCH LA English DT Article; Proceedings Paper CT VIIth Symposium on Solar-Terrestrial Physics CY DEC, 1998 CL MOSCOW, RUSSIA AB The realization of a new method for investigating the geodisturbed region of the solar wind with the help of the ground-based radiotransmitting complex SURA and the Wind spacecraft is reported. We present preliminary results of the experiments on radio occultation in the range of 9 MHz during the last solar activity minimum; the possibilities of the bistatic SURA-Wind radar in studying the structure of the near-Earth and interplanetary plasma are discussed. C1 Nizhni Novgorod State Univ, Radiophys Res Inst, Nizhnii Novgorod 603600, Russia. NASA, Space Flight Ctr, Greenbelt, MD USA. RP Tokarev, YV (reprint author), Nizhni Novgorod State Univ, Radiophys Res Inst, Ul Lyadova 25-14,GSP-51, Nizhnii Novgorod 603600, Russia. NR 4 TC 1 Z9 1 U1 0 U2 1 PU MAIK NAUKA/INTERPERIODICA PI NEW YORK PA C/O KLUWER ACADEMIC-PLENUM PUBLISHERS, 233 SPRING ST, NEW YORK, NY 10013-1578 USA SN 0038-0946 J9 SOLAR SYST RES+ JI Solar Syst. Res. PD MAR-APR PY 2000 VL 34 IS 2 BP 128 EP 131 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357HK UT WOS:000089492300007 ER PT J AU Li, Y Ruge, J Bates, JR Brandt, A AF Li, Y Ruge, J Bates, JR Brandt, A TI A proposed adiabatic formulation of 3-dimensional global atmospheric models based on potential vorticity SO TELLUS SERIES A-DYNAMIC METEOROLOGY AND OCEANOGRAPHY LA English DT Article ID HYBRID ISENTROPIC-SIGMA; VERTICAL COORDINATE; WEATHER PREDICTION; INTEGRATION SCHEME; EQUATIONS; SYSTEMS AB A 2-time-level finite difference atmospheric general circulation model based on the semi-Lagrangian advection of pseudo potential vorticity (which becomes potential vorticity in that parr of the domain where the hybrid vertical coordinate becomes isentropic) has been formulated. At low levels, the hybrid vertical coordinate is terrain following. The problem of isentropic potential vorticity possibly becoming ill-defined in the regions of planetary boundary layer is thus circumvented. The divergence equation is a companion to the (pseudo) potential vorticity equation and the model is thus called a PV-D model. Many features of a previously developed shallow water PV-D model are carried over: a modification of the PV equation needed to give computational stability of long Rossby waves; a semi-Lagrangian semi-implicit treatment of both the linear and the nonlinear terms; the use of an unstaggered grid in the horizontal; the use of a nonlinear multigrid technique to solve the nonlinear implicit equations. A linear numerical stability analysis of the model's gravity-inertia waves indicates that the potential temperature needs to be separated into horizontal mean and perturbation parts. This allows an implicit treatment of the vertical advection associated with the mean in the thermodynamic equation. Numerical experiments with developing baroclinic waves have been carried out and give realistic results. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol, Greenbelt, MD 20771 USA. Univ Colorado, Boulder, CO 80309 USA. Univ Copenhagen, Copenhagen, Denmark. Weizmann Inst Sci, IL-76100 Rehovot, Israel. RP Li, Y (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. NR 30 TC 4 Z9 4 U1 1 U2 1 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6495 J9 TELLUS A JI Tellus Ser. A-Dyn. Meteorol. Oceanol. PD MAR PY 2000 VL 52 IS 2 BP 129 EP 139 DI 10.1034/j.1600-0870.2000.00004.x PG 11 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA 289AV UT WOS:000085597900002 ER PT J AU Thuburn, J Li, Y AF Thuburn, J Li, Y TI Numerical simulations of Rossby-Haurwitz waves SO TELLUS SERIES A-DYNAMIC METEOROLOGY AND OCEANOGRAPHY LA English DT Article ID SEMI-LAGRANGIAN MODELS; STABILITY; ADVECTION; SCHEME AB Simulations of Rossby-Haurwitz waves have been carried out using four different high-resolution numerical shallow water models: a spectral model, two semi-Langrangian models predicting wind components and potential vorticity respectively, and a finite-volume model on a hexagonal-icosahedral grid. The simulations show that (i) unlike the nondivergent case, the shallow water Rossby-Haurwitz wave locally generates small-scale features and so has a potential enstrophy cascade, and (ii) contrary to common belief, the zonal wavenumber 4 Rossby-Haurwitz wave is dynamically unstable and will eventually break down if initially perturbed. Implications of these results for the use of the Rossby-Haurwitz wave as a numerical model test case are discussed. The four models tested give very similar results, giving confidence in the accuracy and robustness of the results. The most noticeable difference between the models is that truncation errors in the hexagonal-icosahedral grid model excite the Rossby-Haurwitz wave instability, causing the wave to break down quickly, whereas for the other models in the configurations tested the instability is excited only by roundoff error at worst, and the Rossby-Haurwitz wave breaks down much more slowly or nor at all. C1 Univ Reading, Dept Meteorol, Reading RG6 6BB, Berks, England. NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol, Greenbelt, MD 20771 USA. RP Thuburn, J (reprint author), Univ Reading, Dept Meteorol, POB 243,Earley Gate, Reading RG6 6BB, Berks, England. NR 15 TC 39 Z9 39 U1 0 U2 1 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6495 J9 TELLUS A JI Tellus Ser. A-Dyn. Meteorol. Oceanol. PD MAR PY 2000 VL 52 IS 2 BP 181 EP 189 DI 10.1034/j.1600-0870.2000.00107.x PG 9 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA 289AV UT WOS:000085597900005 ER PT J AU Lee, LC Rocken, C Kursinski, ER AF Lee, LC Rocken, C Kursinski, ER TI Applications of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) SO TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES LA English DT Editorial Material C1 Natl Space Program Off, Hsinchu, Taiwan. Natl Cheng Kung Univ, Tainan 70101, Taiwan. Univ Corp Atmospher Res, Boulder, CO USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Lee, LC (reprint author), Natl Space Program Off, Hsinchu, Taiwan. NR 0 TC 1 Z9 1 U1 0 U2 1 PU CHINESE GEOSCIENCE UNION PI TAIPEI PA PO BOX 23-59, TAIPEI 10764, TAIWAN SN 1017-0839 J9 TERR ATMOS OCEAN SCI JI Terr. Atmos. Ocean. Sci. PD MAR PY 2000 VL 11 IS 1 BP I EP III PG 3 WC Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Oceanography SC Geology; Meteorology & Atmospheric Sciences; Oceanography GA 306PY UT WOS:000086606100001 ER PT J AU Yunck, TP Liu, CH Ware, R AF Yunck, TP Liu, CH Ware, R TI A history of GPS sounding SO TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES LA English DT Article DE COSMIC; GPS Sounding; atmospheric limb sounding; atmospheric occultation; radio occultation; Global Positioning System; GGI; GPS/MET; Oersted; Sunsat; CHAMP; SAC-C; GRACE; JPL; UCAR; Stanford ID RADIO OCCULTATION MEASUREMENTS; ATMOSPHERE; SYSTEM AB The roots of GPS sounding go back to the first days of interplanetary flight. In the early 1960's teams from Stanford University and the Jet Propulsion Laboratory exploited radio links between Earth and the Mariner 3 and 4 spacecraft to probe the atmosphere and other properties of Mars. Radio science has since been a staple of planetary exploration. Before the advent of GPS, application of radio occultation to Earth was deemed impractical, and it was not immediately evident that even GPS could be usefully adapted. Techniques devised for geodesy in the 1980's, including "codeless" carrier reconstruction, clock elimination by double differencing, GPS-based precise orbit determination, and compact, low-cost receivers, set the stage. JPL submitted the first GPS occultation proposal to NASA in 1988. Though that "GPS Geoscience Instrument" did not fly, it established the concept and led soon to the GPS/MET experiment, conceived by the University Corporation for Atmospheric Research and sponsored by the US National Science Foundation. The remarkable success of GPS/MET has led NASA to mount follow-on experiments on five international missions, launching between 1999 and 2001. Those will refine the systems and techniques of GPS sounding, setting the stage for COSMIC-the first operational GPS occultation constellation. C1 Jet Prop Lab, Pasadena, CA 91109 USA. Natl Cent Univ, Chungli 32054, Taiwan. RP Yunck, TP (reprint author), Jet Prop Lab, M-S 238-540,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 28 TC 72 Z9 77 U1 2 U2 7 PU CHINESE GEOSCIENCE UNION PI TAIPEI PA PO BOX 23-59, TAIPEI 10764, TAIWAN SN 1017-0839 J9 TERR ATMOS OCEAN SCI JI Terr. Atmos. Ocean. Sci. PD MAR PY 2000 VL 11 IS 1 BP 1 EP 20 PG 20 WC Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Oceanography SC Geology; Meteorology & Atmospheric Sciences; Oceanography GA 306PY UT WOS:000086606100002 ER PT J AU Kursinski, ER Hajj, GA Leroy, SS Herman, B AF Kursinski, ER Hajj, GA Leroy, SS Herman, B TI The GPS radio occultation technique SO TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES LA English DT Article DE atmospheric remote sensing; Radio Occultation; data assimilation; temperature; pressure; geopotential height; water vapor; GPS; climate ID GLOBAL POSITIONING SYSTEM; ATMOSPHERIC PROFILES; EARTHS ATMOSPHERE; VOYAGER-2; URANUS AB Radio occultation observations represent a planetary-scale optics experiment in which the atmosphere acts as a lens and alters the propagation velocity and paths of microwave signals passing through it. In this paper we review the process of inverting the radio occultation observations acquired using the Global Positioning System (GPS) in order to derive atmospheric quantities of interest including temperature, geopotential and water vapor. Beginning with geometric optics, we derive the Abel integral used to transform the observations into profiles of refractivity, In the process, we characterize why the Abel transform works so well as a first approximation for deriving atmospheric profiles. We discuss the resolution of the observations and the improvements that can be achieved via the backpropagation concept where the receiver's position is effectively moved closer to the limb of the Earth in post-processing. We discuss several factors that complicate the observations in the Earth's troposphere including critical refraction and atmospheric multipath. Critical refraction refers to the situation where the bending becomes so great that the occulted signal disappears whereas atmospheric multipath refers to the situation where multiple signal paths connect the transmitter and receiver. We describe the derivation of temperature, pressure and water vapor from the observations including the optimal combining of the occultation observations with weather and climate analyses. We describe some key issues in deriving profiles from real data including the correction of dock errors and ionospheric effects, and the estimation of the resolution and atmospheric Doppler in a self-consistent manner. We conclude by summarizing the expected and achieved accuracy and resolution. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Dept Atmospher Sci, Tucson, AZ USA. RP Kursinski, ER (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 46 TC 124 Z9 140 U1 0 U2 9 PU CHINESE GEOSCIENCE UNION PI TAIPEI PA PO BOX 23-59, TAIPEI 10764, TAIWAN SN 1017-0839 J9 TERR ATMOS OCEAN SCI JI Terr. Atmos. Ocean. Sci. PD MAR PY 2000 VL 11 IS 1 BP 53 EP 114 PG 62 WC Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Oceanography SC Geology; Meteorology & Atmospheric Sciences; Oceanography GA 306PY UT WOS:000086606100004 ER PT J AU Leroy, SS North, GR AF Leroy, SS North, GR TI The application of COSMIC data to global change research SO TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES LA English DT Article DE COSMIC; climate change; radio occultation; atmospheric remote sensing ID GRIDPOINT TEMPERATURE ANOMALIES; DETECTING CLIMATE SIGNALS; GENERAL-CIRCULATION MODEL; FLUCTUATION DISSIPATION; RADIOSONDE VALIDATION; SURFACE-TEMPERATURE; FINGERPRINT METHOD; GREENHOUSE-GAS; TIME-SERIES; VARIABILITY AB The constellation observing system for meteorology, ionosphere, and climate (COSMIC) is well-suited to climate research, especially as it pertains to climate modeling. It presents a challenge to climate models, which are currently tuned to match climate mean states, by providing precisely calibrated data which can be analyzed according to two methods that are insensitive to standard model tuning. Those two methods are climate signal detection and second-moment statistics, both of which consider the most useful climate model to be the one which provides the best predictions rather than the one which best recreates the current climate. In this paper we discuss these two new, alternative approaches to improving climate models and how COSMIC occultation data can be analyzed in this context. Climate signal detection is usually applied to determine what trends in a climate data set can be described by external effects, such as increasing greenhouse gas concentrations, sulfur dioxide aerosols, etc. Here we show that it is actually a method to test climate models. By examining climate trends and anomalies as revealed by COSMIC data, we can test whether climate models reproduce those trends and anomalies. We describe in detail how trends and anomalies can be extracted from COSMIC occultation data and the relevance it should have to climate models. The fluctuation dissipation theorem, as applied to the climate, shows that a second-moment analysis of a climate model's output will reveal more about its physical soundness than does the mean states it produces. While this theorem shows how a Green's function for climate change can be derived from the second-moments of the climate system, it is best applied by comparing like second-moments in data and in model output. This method of testing models is most likely to reveal which parameterizations of convection and moisture dispersion are most appropriate. The two methods of improving climate models are discussed in the context of COSMIC, showing how the occultation data can be processed to apply each of them. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Texas A&M Univ, Dept Meteorol, College Stn, TX USA. RP Leroy, SS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-237, Pasadena, CA 91109 USA. RI North, Gerald/G-1019-2011 NR 48 TC 11 Z9 11 U1 1 U2 5 PU CHINESE GEOSCIENCE UNION PI TAIPEI PA PO BOX 23-59, TAIPEI 10764, TAIWAN SN 1017-0839 J9 TERR ATMOS OCEAN SCI JI Terr. Atmos. Ocean. Sci. PD MAR PY 2000 VL 11 IS 1 BP 187 EP 210 PG 24 WC Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Oceanography SC Geology; Meteorology & Atmospheric Sciences; Oceanography GA 306PY UT WOS:000086606100007 ER PT J AU Hajj, GA Lee, LC Pi, XQ Romans, LJ Schreiner, WS Straus, PR Wang, CM AF Hajj, GA Lee, LC Pi, XQ Romans, LJ Schreiner, WS Straus, PR Wang, CM TI COSMIC GPS ionospheric sensing and space weather SO TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES LA English DT Article DE GPS occultations; ionospheric profiling; ionospheric sensing; ionospheric data assimilation; space weather; COSMIC mission ID GLOBAL POSITIONING SYSTEM; TOTAL ELECTRON-CONTENT; RADIO OCCULTATION; VERTICAL RESOLUTION; EARTHS ATMOSPHERE; DENSITY; TOMOGRAPHY; PROFILES; MODELS AB As our civilization becomes more dependent on space based technologies, we become more vulnerable to conditions in space weather. Accurate space weather specification and forecasting require proper modeling which account for the coupling between the sun, the magnetosphere, the thermosphere, the ionosphere and the mesosphere. In spite of the tremendous advances that have been made in understanding the physics behind different space weather phenomena, the ability to specify or predict space weather is limited due to the lack of continuous and extensive observations in these regions. Placing a constellation of GPS receivers in low-Earth orbit, such as the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), provides an extremely powerful system for continuously and extensively measuring one of these regions, the ionosphere. COSMIC, by use of GPS occultations, will make it possible to obtain continuous and global 3-dimensional images of electron density, irregularities and TIDs in the ionosphere and plasmasphere. COSMIC would provide nearly 5600 globally distributed occultations per day suitable for ionospheric sensing. Occultations can be processed individually to obtain vertical profiles of electron density, with vertical resolution of similar to 1km, or collectively by means of tomography or data assimilation to obtain 3-D images of electron density or irregularity structure. In this paper we describe the GPS observables for ionospheric sensing and the occultation geometry. Our presentation evolves from discussing simple to more complicated inversion techniques starting with the Abel inversion, gradient-constrained Abel inversion, tomography, and finally data assimilation. In each of these techniques, the accuracy is assessed either via examination of real data from GPS/MET or via simulation. Brief discussions of measuring ionospheric irregularities and TIDs are given. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ So Calif, Dept Math Appl, Los Angeles, CA 90089 USA. Natl Space Program Off, Hsinchu, Taiwan. Univ Corp Atmospher Res, Boulder, CO 80303 USA. Aerospace Corp, El Segundo, CA 90245 USA. RP Hajj, GA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Lee, Lou-Chuang/I-2588-2013 OI Lee, Lou-Chuang/0000-0003-4012-991X NR 36 TC 101 Z9 103 U1 2 U2 6 PU CHINESE GEOSCIENCE UNION PI TAIPEI PA PO BOX 23-59, TAIPEI 10764, TAIWAN SN 1017-0839 J9 TERR ATMOS OCEAN SCI JI Terr. Atmos. Ocean. Sci. PD MAR PY 2000 VL 11 IS 1 BP 235 EP 272 PG 38 WC Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Oceanography SC Geology; Meteorology & Atmospheric Sciences; Oceanography GA 306PY UT WOS:000086606100009 ER PT J AU Chao, BF Pavlis, EC Hwang, CW Liu, CC Shum, CK Tseng, CL Yang, M AF Chao, BF Pavlis, EC Hwang, CW Liu, CC Shum, CK Tseng, CL Yang, M TI COSMIC: Geodetic applications in improving earth's gravity model SO TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES LA English DT Article DE gravity field; gravity model; orbit determination; satellite tracking ID TRACKING DATA; GPS AB The routine GPS tracking data that will be collected for the precise orbit determination of the eight COSMIC spacecraft will contain valuable information about the terrestrial gravity field. Numerical simulations based on current straw-man mission scenarios have shown: (1) For the static model of the gravity field, significant improvement is possible over our present knowledge embodied in the EGM96 model, out to harmonic degree as high as 40. (2) With respect to time-varying gravitational signals, large-scale mass transport processes in the geophysical fluids (e.g., atmosphere and oceans) can be detected or monitored during the mission, providing important global change information. Further sophisticated simulations incorporating more realistic force models will be needed once COSMIC mission scenario and spacecraft design are completely defined. C1 NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Greenbelt, MD 20771 USA. Univ Maryland, NASA, Goddard Space Flight Ctr, JCET, Greenbelt, MD USA. Natl Chaio Tung Univ, Dept Civil Engn, Hsinchu, Taiwan. Acad Sinica, Inst Earth Sci, Taipei, Taiwan. Ohio State Univ, Dept Civil & Environm Engn & Geodet Sci, Columbus, OH 43210 USA. Natl Cheng Kung Univ, Dept Surveying Engn, Tainan 70101, Taiwan. RP Chao, BF (reprint author), NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Greenbelt, MD 20771 USA. RI Chao, Benjamin Fong/N-6156-2013 NR 13 TC 11 Z9 14 U1 0 U2 0 PU CHINESE GEOSCIENCE UNION PI TAIPEI PA PO BOX 23-59, TAIPEI 10764, TAIWAN SN 1017-0839 J9 TERR ATMOS OCEAN SCI JI Terr. Atmos. Ocean. Sci. PD MAR PY 2000 VL 11 IS 1 BP 365 EP 378 PG 14 WC Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Oceanography SC Geology; Meteorology & Atmospheric Sciences; Oceanography GA 306PY UT WOS:000086606100015 ER PT J AU Timofeeva, TV Nesterov, VN Antipin, MY Clark, RD Sanghadasa, M Cardelino, BH Moore, CE Frazier, DO AF Timofeeva, TV Nesterov, VN Antipin, MY Clark, RD Sanghadasa, M Cardelino, BH Moore, CE Frazier, DO TI Molecular modeling and experimental study of non-linear optical compounds: monosubstituted derivatives of dicyanovinylbenzene SO JOURNAL OF MOLECULAR STRUCTURE LA English DT Article DE cyanoderivatives; non-linear optical properties; X-ray analysis; ab initio calculations ID MM3 FORCE-FIELD; CRYSTAL-STRUCTURES; ORGANIC-MOLECULES; POLARIZABILITIES; MECHANICS; HYDROCARBONS; POTENTIALS AB A search for potential non-linear optical (NLO) compounds has been performed using the Cambridge Structural Database and molecular modeling. We have studied a series of monosubstituted derivatives of dicyanovinylbenzene as the NLO proper ties of one of its derivatives (o-methoxy-dicyanovinylbenzene, DIVA) were described earlier. The molecular geometry in the series of the compounds studied was investigated with an X-ray analysis and discussed along with results of molecular mechanics and ab initio quantum chemical calculations. The influence of crystal packing on the molecular planarity has been revealed. Two new compounds from the series studied were found to be active in the second harmonic generation (SHG) in the powder state. The measurements of the SHG efficiency have shown that the o-F-, and p-Cl-derivatives of dicyanovinylbenzene are about 10 and 20 times more active than urea, respectively. The peculiarities of crystal structure formation in the framework of balance between the van der Waals and electrostatic interactions have been discussed. The crystal morphology of DIVA and two new SHG-active compounds have been calculated on the basis of the known crystal structures. (C) 2000 Elsevier Science B.V. All rights reserved. C1 New Mexico Highlands Univ, Dept Phys Sci, Las Vegas, NM 87701 USA. Russian Acad Sci, Inst Organoelement Cpds, Moscow, Russia. Univ Alabama, Huntsville, AL 35899 USA. Atlanta Univ Ctr, Spelman Coll, Dept Chem, Atlanta, GA 30314 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Timofeeva, TV (reprint author), New Mexico Highlands Univ, Dept Phys Sci, Las Vegas, NM 87701 USA. NR 40 TC 13 Z9 13 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-2860 J9 J MOL STRUCT JI J. Mol. Struct. PD FEB 29 PY 2000 VL 519 BP 225 EP 241 DI 10.1016/S0022-2860(99)00305-1 PG 17 WC Chemistry, Physical SC Chemistry GA 291FE UT WOS:000085722800025 ER PT J AU Goldsby, JC AF Goldsby, JC TI Temperature-dependent elastic and anelastic behavior of silicon-based fiber-reinforced silicon carbide ceramic matrix composites SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article DE composite; internal friction; damping; high temperature; silicon carbide; fiber-reinforced ceramic composite ID INTERNAL-FRICTION; STATE AB Temperature-dependent elastic and anelastic properties of silicon-based fiber-reinforced silicon carbide ceramic matrix composites were determined by establishing continuous flexural vibrations in the material at its lowest resonance (eigen) frequency. Anelastic behavior as a function of temperature was determined by observation of the time-dependent amplitude free decay of the sample. The elastic modulus of all the materials studied decreased with increasing temperature, with the exception of carbon fiber-reinforced silicon carbide (C/SiC). Elastic behavior between ceramics is similar up to 600 degrees C, above which material behavior differentiates. Melt-infiltrated composite materials exhibited the greatest modulus decrease to only 88% of its room temperature value at 1200 degrees C. Anelastic strain-independent behavior of composites and monoliths display constant internal friction from room temperature to 400 degrees C. Above 400 degrees C, internal friction differentiates depending upon fabrication method. The highest internal friction occurs in Slyramic fiber-reinforced melt-infiltrated silicon carbide (SiC/SiC) with a value of 200 x 10(-4) in units of logarithmic decrement (log dec). With the high-temperature background removed, an energy absorption peak with a height of 100 x 10(-4) log dec is observed centered at 800 degrees C. (C) 2000 Elsevier Science S.A. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Goldsby, JC (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 30 TC 16 Z9 18 U1 2 U2 9 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD FEB 29 PY 2000 VL 279 IS 1-2 BP 266 EP 274 DI 10.1016/S0921-5093(99)00630-9 PG 9 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 279WZ UT WOS:000085069200033 ER PT J AU Khan, MA Yang, JW Simin, G Gaska, R Shur, MS zur Loye, HC Tamulaitis, G Zukauskas, A Smith, DJ Chandrasekhar, D Bicknell-Tassius, R AF Khan, MA Yang, JW Simin, G Gaska, R Shur, MS zur Loye, HC Tamulaitis, G Zukauskas, A Smith, DJ Chandrasekhar, D Bicknell-Tassius, R TI Lattice and energy band engineering in AlInGaN/GaN heterostructures SO APPLIED PHYSICS LETTERS LA English DT Article ID FIELD-EFFECT TRANSISTORS AB We report on structural, optical, and electrical properties of AlxInyGa1-x-yNGaN heterostructures grown on sapphire and 6H-SiC substrates. Our results demonstrate that incorporation of In reduces the lattice mismatch, Delta a, between AlInGaN and GaN, and that an In to Al ratio of close to 1:5 results in nearly strain-free heterostructures. The observed reduction in band gap, Delta E-g, determined from photoluminescence measurements, is more than 1.5 times higher than estimated from the linear dependencies of Delta a and Delta E-g on the In molar fraction. The incorporation of In and resulting changes in the built-in strain in AlInGaN/GaN heterostructures strongly affect the transport properties of the two-dimensional electron gas at the heterointerface. The obtained results demonstrate the potential of strain energy band engineering for GaN-based electronic applications. (C) 2000 American Institute of Physics. [S0003-6951(00)03909-7]. C1 Univ S Carolina, Dept Elect & Comp Engn, Columbia, SC 29208 USA. Rensselaer Polytech Inst, Dept Elect Comp & Syst Engn, Troy, NY 12180 USA. Univ S Carolina, Dept Chem & Biochem, Columbia, SC 29208 USA. Vilnius State Univ, Inst Mat Sci & Appl Res, Vilnius, Lithuania. Arizona State Univ, Ctr Solid State Sci, Ctr High Resolut Electron Microscopy, Tempe, AZ 85287 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Khan, MA (reprint author), Univ S Carolina, Dept Elect & Comp Engn, Columbia, SC 29208 USA. RI Shur, Michael/A-4374-2016 OI Shur, Michael/0000-0003-0976-6232 NR 11 TC 119 Z9 120 U1 0 U2 33 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD FEB 28 PY 2000 VL 76 IS 9 BP 1161 EP 1163 DI 10.1063/1.125970 PG 3 WC Physics, Applied SC Physics GA 286PT UT WOS:000085454900027 ER PT J AU Cunnold, DM Newchurch, MJ Flynn, LE Wang, HJ Russell, JM McPeters, R Zawodny, JM Froidevaux, L AF Cunnold, DM Newchurch, MJ Flynn, LE Wang, HJ Russell, JM McPeters, R Zawodny, JM Froidevaux, L TI Uncertainties in upper stratospheric ozone trends from 1979 to 1996 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EXPERIMENT-II MEASUREMENTS; NIMBUS-7 SBUV; AEROSOL; UMKEHR; VALIDATION; PROFILES; CALIBRATION; SATELLITE; HALOGEN AB The time series of differences in coincident measurements of ozone by Stratospheric Aerosol and Gas Experiment (SAGE) and by Solar Backscattered Ultraviolet (SBUV), SBUV/2, Umkehr and Microwave Limb Sounder (MLS) are analyzed, and the slopes in the differences are calculated. SAGE ozone measurements are also compared against those by HALOE. The purpose of these comparisons is to look for statistically significant nonzero slopes which could indicate long-term calibration problems in one or more of the measurement systems. It is found that the slopes are remarkably similar between the Northern and Southern Hemisphere midlatitudes, and, apart from a few exceptions, the slopes are also similar in the tropics. Slopes of MLS-SAGE differences and HALOE-SAGE trends from approximately 1992 to 1996 have values of approximately -0.5 +/- 0.4% yr(-1) (95% confidence limits) in Umkehr layers 7-9 (which are centered at similar to 37, 42, and 47 km altitude). Umkehr-SAGE slopes for 1979-1996, however, are almost all positive and in the range -0.1-0.3% yr-(1) for Umkehr layers 4-8, while SBUV-SAGE slopes for 1979-1989 are essentially zero in layers 4-7 and 0.3-0.4% yr(-1) in layers 8 and 9. Averaging all these results with SBUV-SAGE II slopes from 1985 to 1989, the other sensors minus SAGE slopes are most likely between 0.2 and -0.2% yr(-1) from similar to 20 to 40 km altitude. The results indicate slightly negative slopes in Umkehr layers 5-7 and positive slopes in the other three layers. There thus appears to be no overall drift in the SAGE ozone measurements from 1979 to 1996, but SAGE sunrise/sunset trend differences >40 km altitude, combined with the more accurate SBUV-SAGE slopes for 1979-1989, suggest a most likely slope range of 0.4 to -0.4% yr(-1) between 40 and 50 km altitude. SBUV/2 measurements from 1989 to 1994 have an upward trend with respect to SAGE measurements of similar to 0.7% yr(-1) with some altitudinal structure: this slope exceeds the estimated 95% uncertainties on the SBUV/2 trends. C1 Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. Georgia Tech, Sch Earth & Atmospher Sci, Atlanta, GA USA. Univ Alabama, Dept Atmospher Sci, Huntsville, AL 35807 USA. NOAA, Natl Environm Satellite Data & Informat Serv, Off Res & Applicat, Washington, DC 20233 USA. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Georgia Inst Technol, Sch Earth & Atmospher Sci, 221 Bobby Dooe Way, Atlanta, GA 30332 USA. EM cunnold@eas.gatech.edu RI Flynn, Lawrence/B-6321-2009; McPeters, Richard/G-4955-2013 OI Flynn, Lawrence/0000-0001-6856-2614; McPeters, Richard/0000-0002-8926-8462 NR 39 TC 23 Z9 25 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 4427 EP 4444 DI 10.1029/1999JD900313 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800005 ER PT J AU Cunnold, DM Wang, HJ Thomason, LW Zawodny, JM Logan, JA Megretskaia, IA AF Cunnold, DM Wang, HJ Thomason, LW Zawodny, JM Logan, JA Megretskaia, IA TI SAGE (version 5.96) ozone trends in the lower stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID II DATA; AEROSOL; VALIDATION; INVERSION AB Ozone retrievals from Stratospheric Aerosol and Gas Experiment (SAGE) II Version 5.96 (v5.96) below similar to 25 km altitude are discussed. This version of the algorithm includes improved constraints on the wavelength dependence of aerosol extinctions based on the ensemble of aerosol size distribution measurements. This results in a reduction of SAGE ozone errors in the 2 years after the Mount Pinatubo eruption. However, SAGE ozone concentrations are still similar to 10% larger than ozonesonde and Halogen Occultation Experiment (HALOE) measurements below 20 km altitude under nonvolcanic conditions (and by more than this in the tropics). The analysis by Steele and Turco [1997] suggests that the SAGE ozone overpredictions are in the wrong direction to be explained by aerosol extinction extrapolation errors. Moreover, preliminary SAGE II v6.0a retrievals suggest that they are partially accounted for by geometric difficulties at low altitudes in v5.96 and prior retrievals. SAGE ozone trends for the 1979-1996 and 1984-1996 periods are calculated and compared, and the sources of trend errors are discussed. These calculations are made after filtering out ozone data during periods of high, local aerosol extinctions. In the lower stratosphere, below similar to 28 km altitude, there is shown to be excellent agreement in the altitudinal structure of ozone decreases at 45 degrees N between SAGE and ozonesondes with the largest decrease in both between 1979 and 1996 having occurred below 20 km altitude, amounting to 0.9 +/- 0.7% yr(-1) (2 sigma) at 16 km altitude. However, in contrast to the fairly steady decreases at 45 degrees N, both SAGE measurements and Lauder ozonesondes show ozone increases at 45 degrees S over the period from the mid-1980s to 1996 of 0.2 +/- 0.5% yr(-1) (2 sigma) from 15 to 20 km altitude. The SAGE data suggest that this increase is a wintertime phenomenon which occurs in the 15-20 km height range. Changes in dynamics are suggested as the most likely cause of this increase. These hemispheric differences in ozone trends are supported by ozone column measurements by the Total Ozone Mapping Spectrometer (TOMS). C1 Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA. RP Georgia Inst Technol, Sch Earth & Atmospher Sci, 221 Bobby Dodd Way, Atlanta, GA 30332 USA. EM cunnold@eas.gatech.edu OI Thomason, Larry/0000-0002-1902-0840 NR 23 TC 25 Z9 26 U1 2 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 4445 EP 4457 DI 10.1029/1999JD900976 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800006 ER PT J AU Ricaud, P Chipperfield, MP Waters, JW Russell, JM Roche, AE AF Ricaud, P Chipperfield, MP Waters, JW Russell, JM Roche, AE TI Temporal evolution of chlorine monoxide in the middle stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OZONE; CLO; ATMOSPHERE; VALIDATION; SOUNDER; UARS AB The temporal evolution of stratospheric chlorine monoxide (ClO) at northern midlatitudes is studied over different scales: diurnal and seasonal variations. Data sets include temperature profiles, and ClO, HCl, ClONO2, NO2, O-3, H2O, and CH4 mixing ratios as measured from 10 to 0.46 hPa (i.e., from similar to 30 to similar to 55 km) by the Microwave Limb Sounder (MLS), by the Halogen Occultation Experiment, and by the Cryogenic Limb Array Etalon Spectrometer instruments aboard the UARS satellite from at most September 1991 to June 1997 within the band 40 degrees-50 degrees N. The time evolution of these species is interpreted by comparison with results from a "zero-dimensional" (0-D) purely photochemical model and from the SLIMCAT three-dimensional (3-D) chemical transport model over the Plateau de Bure station (45 degrees N, 10 degrees E) from September 1991 to March 1998. A maximum confidence value for the yield in the reaction ClO + OH --> HCl + O-2 is deduced from the analysis to be in the range 0.05-0.10+/-0.03, which is consistent with recent laboratory data, suggesting a value of similar to 0.05-0.06+/-0.02. Comparisons between the ClO diurnal variations measured by MLS and calculated by the 0-D model agree to within 10% around the maximum of ClO (similar to 40 km) and within 5% elsewhere. The ClO diurnal variation is induced by variations in the partitioning with HOCl and ClONO2 below 50 km and by variations in the partitioning within the ClOx (=Cl+ClO) family above. The agreement between measured and modeled seasonal variations of ClO implies an evolution above 30 km essentially dictated by the variation in the partitioning with HCl, together with the partitioning within the ClOx family above 40 km. The differences between measured and modeled ClO seasonal variations above 50 km are attributed to uncertainties in the relative rates of the sources of HCl (reactions of Cl with CH4 and HO2). C1 Observ Bordeaux, CNRS, INSU, F-33270 Floirac, France. Univ Leeds, Sch Environm, Leeds LS2 9JT, W Yorkshire, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94303 USA. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. RP Observ Bordeaux, CNRS, INSU, BP 89, F-33270 Floirac, France. EM ricaud@observ.u-bordeaux.fr RI Chipperfield, Martyn/H-6359-2013 OI Chipperfield, Martyn/0000-0002-6803-4149 NR 27 TC 11 Z9 11 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 4459 EP 4469 DI 10.1029/1999JD900995 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800007 ER PT J AU Froidevaux, L Waters, JW Read, WG Connell, PS Kinnison, DE Russell, JM AF Froidevaux, L Waters, JW Read, WG Connell, PS Kinnison, DE Russell, JM TI Variations in the free chlorine content of the stratosphere (1991-1997): Anthropogenic, volcanic, and methane influences SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID IN-SITU MEASUREMENTS; LONG-TERM TREND; SULFATE AEROSOLS; OZONE DEPLETION; MOUNT-PINATUBO; MT-PINATUBO; CLO; NO2; ERUPTION; CHLOROFLUOROCARBONS AB Remote sensing of chlorine monoxide (ClO) by the Microwave Limb Sounder experiment aboard the Upper Atmosphere Research Satellite (UARS) has provided global measurements of variations in stratospheric free chlorine for 1991-1997. Linear trends were obtained from a multiple regression analysis of this data set at low latitudes and midlatitudes. ClO increases in the upper stratosphere (2 hPa) are significantly larger than expected from trends in chlorine source gases alone. Much of the upper stratospheric ClO variability can be explained by changes in CH4, as measured by the UARS Halogen Occultation Experiment. Decreasing ClO in the lower stratosphere is consistent with a relaxation from a chemically perturbed state attributed to the 1991 Mt. Pinatubo eruption. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-701, Pasadena, CA 91109 USA. EM lucien@mls.jpl.nasa.gov; connell2@llnl.gov; dkin@acd.ucar.edu NR 42 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 4471 EP 4481 DI 10.1029/1999JD901039 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800008 ER PT J AU Anderson, J Russell, JM Solomon, S Deaver, LE AF Anderson, J Russell, JM Solomon, S Deaver, LE TI Halogen occultation experiment confirmation of stratospheric chlorine decreases in accordance with the Montreal Protocol SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID UARS PLATFORM; VALIDATION; INCREASE; FLUORINE; BUDGET AB Near-global time series of Halogen Occultation Experiment (HALOE) derived total Cl, F, and the Cl/F ratio were evaluated and compared with data from two ground-based CFC measurement programs and United Nations Environment Programme (UNEP) best-case scenarios for CFC emissions. The HALOE CI profiles confirm that the chlorine burden near the stratopause is decreasing and this decrease is driven by tropospheric decreases of methyl chloroform. The HALOE F profiles show that the fluorine burden near the stratopause is primarily influenced by CFC-12. The Cl/F ratio, which is insensitive to transport effects at 55 km, shows that the atmosphere near the stratopause is becoming more fluorinated since the inception of the HALOE mission and less chlorinated since the start of 1997. The temporal changes in the derived Cl, F, and Cl/F ratio at 55 km are in accord with UNEP projections and in situ observations. These combined results demonstrate that the Montreal Protocol and subsequent strengthening amendments are currently having the desired effect of reducing stratospheric chlorine. C1 Hampton Univ, Dept Phys, Ctr Atmospher Sci, Hampton, VA 23668 USA. NOAA, Aeron Lab, Boulder, CO 80303 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hampton Univ, Dept Phys, Ctr Atmospher Sci, 23 Tyler St, Hampton, VA 23668 USA. EM john.anderson@hamptonu.edu; james.russell@hamptonu.edu; solomon@al.noaa.gov NR 15 TC 58 Z9 59 U1 0 U2 13 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 4483 EP 4490 DI 10.1029/1999JD901075 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800009 ER PT J AU Dong, XQ Minnis, P Ackerman, TP Clothiaux, EE Mace, GG Long, CN Liljegren, JC AF Dong, XQ Minnis, P Ackerman, TP Clothiaux, EE Mace, GG Long, CN Liljegren, JC TI A 25-month database of stratus cloud properties generated from ground-based measurements at the Atmospheric Radiation Measurement Southern Great Plains Site SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLIMATE MODELS; WATER CLOUDS; PARAMETERIZATION; EARTH AB A 25-month database of the macrophysical, microphysical, and radiative properties of isolated and overcast low-level stratus clouds has been generated using a newly developed parameterization and surface measurements from the Atmospheric Radiation Measurement central facility in Oklahoma. The database (5-min resolution) includes two parts: measurements and retrievals. The former consist of cloud base and top heights, layer-mean temperature, cloud liquid water path, and solar transmission ratio measured by a ground-based lidar/ceilometer and radar pair, radiosondes, a microwave radiometer, and a standard Eppley precision spectral pyranometer, respectively. The retrievals include the cloud-droplet effective radius and number concentration and broadband shortwave optical depth and cloud and top-of-atmosphere albedos. Stratus without any overlying mid or high-level clouds occurred most frequently during winter and least often during summer. Mean cloud-layer altitudes and geometric thicknesses were higher and greater, respectively, in summer than in winter. Both quantities are positively correlated with the cloud-layer mean temperature. Mean cloud-droplet effective radii range from 8.1 mu m in winter to 9.7 mu m during summer, while cloud-droplet number concentrations during winter are nearly twice those in summer. Since cloud liquid water paths are almost the same in both seasons, cloud optical depth is higher during the winter, leading to greater cloud albedos and lower cloud transmittances. C1 Univ Utah, Dept Meteorol, Salt Lake City, UT 84112 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Pacific NW Lab, Richland, WA 99352 USA. Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA. US DOE, Ames Lab, Ctr Nondestruct Evaluat, Ames, IA 50011 USA. RP Univ Utah, Dept Meteorol, 819 Wm C Browning Bldg, Salt Lake City, UT 84112 USA. EM xdong@met.utah.edu; p.minnis@larc.nasa.gov; Thomas.Ackerman@pnl.gov; cloth@essc.psu.edu; mace@met.utah.edu; long@essc.psu.edu; jim@ultral.cnde.iastate.edu RI Minnis, Patrick/G-1902-2010; OI Minnis, Patrick/0000-0002-4733-6148; Dong, Xiquan/0000-0002-3359-6117 NR 24 TC 43 Z9 44 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 4529 EP 4537 DI 10.1029/1999JD901159 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800013 ER PT J AU Lu, CH Yue, GK Manney, GL Jager, H Mohnen, VA AF Lu, CH Yue, GK Manney, GL Jager, H Mohnen, VA TI Lagrangian approach for Stratospheric Aerosol and Gas Experiment (SAGE) II profile intercomparisons SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDLATITUDE LIDAR BACKSCATTER; EXTINCTION MEASUREMENTS; VALIDATION; OZONESONDES AB Trajectory calculations are employed to identify Stratospheric Aerosol and Gas Experiment (SAGE) II flights sampling the same air mass as is observed by a groundbased aerosol lidar at Garmisch-Partenkirchen, Germany (47.5 degrees N, 11.1 degrees E, 735 m above sea level), during the periods of January-April 1993 and January-December 1998. Intercomparisons between lidar-observed and SAGE II-derived backscatters at 532 nm are conducted. Percentage differences between trajectory-tracked SAGE II profiles and ground-based lidar observations with respect to aerosol lidar are generally within 20-40%, though localized discrepancies >50% are found for some cases. In addition, aerosol extinction, aerosol to molecular extinction ratio, and ozone mixing ratio profiles obtained from the SAGE II flights overpassing the vicinity of Garmisch-Partenkirchen during the January-April 1993 period are compared with profiles obtained from corresponding trajectory-tracked SAGE II flights. Percentage discrepancies between SAGE II ozone profiles are generally within 10-20% above the Junge layer. Data comparisons for aerosol profiles show mixed results. While some cases agree within the error bars, there are several cases where percentage discrepancies exceed 50%. C1 SUNY Albany, Atmospher Sci Res Ctr, Albany, NY 12203 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. New Mexico Highlands Univ, Dept Phys, Las Vegas, NM 87701 USA. Fraunhofer Inst Atmosphar Umweltforsch, D-82467 Garmisch Partenkirchen, Germany. RP SUNY Albany, Atmospher Sci Res Ctr, Albany, NY 12203 USA. EM sarah@asrc.cestm.albany.edu RI Garmisch-Pa, Ifu/H-9902-2014 NR 29 TC 10 Z9 10 U1 2 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 4563 EP 4572 DI 10.1029/1999JD901077 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800016 ER PT J AU Valero, FPJ Minnis, P Pope, SK Bucholtz, A Bush, BC Doelling, DR Smith, WL Dong, XQ AF Valero, FPJ Minnis, P Pope, SK Bucholtz, A Bush, BC Doelling, DR Smith, WL Dong, XQ TI Absorption of solar radiation by the atmosphere as determined using satellite, aircraft, and surface data during the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLOUD ABSORPTION; STRATOCUMULUS CLOUDS; FLUXES; UNCERTAINTIES; RETRIEVAL; ALGORITHM; ENERGY; MODELS; ABSORB AB Data sets acquired during the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE) using simultaneous measurements from five independent platforms (GOES 8 geostationary satellite, ER-2, Egrett and Twin Otter aircraft, and surface) are analyzed and compared. A consistent data set can be built for selected days during ARESE on the basis of the observations from these platforms. The GOES 8 albedos agree with the ER 2, Egrett, and Twin Otter measured instantaneous albedos within 0.013 +/- 0.016, 0.018 +/- 0.032, and 0.006 +/- 0.011, respectively. It is found that for heavy overcast conditions the aircraft measurements yield an absorptance of 0.32 +/- 0.03 for the layer between the aircraft (0.5-13 km), while the GOES 8 albedo versus surface transmittance analysis gives an absorptance of 0.33 +/- 0.04 for the total atmosphere (surface to top). The absorptance of solar radiation estimated by model calculations for overcast conditions varies between 0.16 and 0.24, depending on the model used and on cloud and aerosol implementation. These results are in general agreement with recent findings for cloudy skies, but here a data set that brings together independent simultaneous observations (satellite, surface, and aircraft) is used. Previous ARESE results are reexamined in light of the new findings, and it is concluded that the overcast absorptance in the 0.224-0.68 mu m spectral region ranges between 0.04 +/- 0.06 and 0.08 +/- 0.06, depending on the particular case analyzed. No evidence of excess clear-sky absorption beyond model and experimental errors is found. C1 Univ Calif San Diego, Scripps Inst Oceanog, Ctr Atmospher Sci, Atmospher Res Lab, La Jolla, CA 92093 USA. AS&M Inc, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Univ Calif San Diego, Scripps Inst Oceanog, Ctr Atmospher Sci, Atmospher Res Lab, 9500 Gillman Dr, La Jolla, CA 92093 USA. EM fvalero@ucsd.edu RI Minnis, Patrick/G-1902-2010; OI Minnis, Patrick/0000-0002-4733-6148; Dong, Xiquan/0000-0002-3359-6117 NR 61 TC 22 Z9 22 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 4743 EP 4758 DI 10.1029/1999JD901063 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800029 ER PT J AU Kalliskota, S Kaurola, J Taalas, P Herman, JR Celarier, EA Krotkov, NA AF Kalliskota, S Kaurola, J Taalas, P Herman, JR Celarier, EA Krotkov, NA TI Comparison of daily UV doses estimated from Nimbus 7/TOMS measurements and ground-based spectroradiometric data SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TOTAL OZONE; SATELLITE ESTIMATION; EARTHS SURFACE; IRRADIANCE; ULTRAVIOLET; RADIATION; REFLECTIVITY; ALBEDO; CLOUDS; TRENDS AB During recent years, methods have been developed for estimating UV irradiance reaching the Earth's surface using satellite-measured backscattered UV radiances. The NASA-developed method is based on radiative transfer calculations and satellite measurements of parameters affecting UV radiation: extraterrestrial solar irradiance, atmospheric ozone, cloud reflectivity, aerosol amounts, and ground albedo. In this work a comparison is made between daily UV erythemal doses estimated from Nimbus-7/TOMS measurements (from 1991 to May 1993) and those calculated from ground-based spectroradiometer data. Three stations operated by the National Science Foundation were chosen for this comparison: Ushuaia, Argentina (for 573 days), Palmer, Antarctica (for 450 days), and San Diego, California, (for 149 days). These stations were selected to illustrate the differences between ground-based measurements using the same type of instrument, SUV-100 double monochromator spectroradiometers, and satellite estimates of surface UV irradiance under three different environmental conditions (mountains and snow, nearly continuous snow cover, and midlatitude urban sea level conditions). Averaging the measured and TOMS-estimated doses over periods from 1 week to 1 month improves the agreement. The daily or monthly mean bias increases during months when there is snow/ice on the surface. TOMS has a larger estimate of the UV irradiance by 25% at San Diego (no snow), in agreement with the summer-month analysis of Toronto irradiances [Herman et al., 1999]. TOMS underestimates the average daily-UV dose at Ushuaia (monthly mean bias of -13%) and at Palmer (-35%) consistent with snow/ice with cloud effects not being properly accounted for in the TOMS algorithm. When the reflectivity at all three sites is low (no snow), the TOMS irradiance estimate is larger than the SUV-100 measurements consistent with previously analyzed Brewer data at Toronto. The effects of local fog or clouds smaller than the satellite field of view and undetected UV-absorbing aerosols near the ground are discussed. In addition to uncertainties in radiometric calibrations of the spectrometers, none of the SUV-100 data are corrected for deviations of diffuser-transmittance from true cosine response. C1 Finnish Meteorol Inst, FIN-00101 Helsinki, Finland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Software Corp Amer, Beltsville, MD USA. Raytheon ITSS Corp, Lanham, MD USA. RP Finnish Meteorol Inst, POB 503, FIN-00101 Helsinki, Finland. EM sari.kalliskota@fmi.fi RI Krotkov, Nickolay/E-1541-2012; OI Krotkov, Nickolay/0000-0001-6170-6750; Herman, Jay/0000-0002-9146-1632 NR 32 TC 68 Z9 69 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2000 VL 105 IS D4 BP 5059 EP 5067 DI 10.1029/1999JD900926 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 287NU UT WOS:000085512800065 ER PT J AU Tamppari, LK Zurek, RW Paige, DA AF Tamppari, LK Zurek, RW Paige, DA TI Viking era water-ice clouds SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INFRARED THERMAL MAPPER; MARTIAN ATMOSPHERE; SURFACE-COMPOSITION; PHYSICAL-PROPERTIES; STORM ZONES; MARS; DUST; CYCLE; VARIABILITY; MARINER-9 AB We have spatially and temporally mapped water ice clouds on Mars for 1.25 Martian years using the Viking infrared thermal mapper (IRTM) data. Our technique compares brightness temperatures in the 11 and 20 mu m IRTM channels, utilizing the 11 mu m water ice absorption feature. A complication arises because of the surface nonunit and wavelength-dependent emissivities. We developed a technique for removal of this effect. Using a surface thermal model, we calculated brightness temperatures and their differences for the IRTM channels resulting from the surface emissivity effect alone. These were then subtracted from the measured brightness temperatures, yielding brightness temperature differences dominated by atmospheric effects. The ability to identify water ice clouds in the infrared provides potential new information about particle size and physical processes by comparing these clouds to those seen in visible wavelengths. We found that water ice clouds were more widespread and frequent during the Viking period than had been previously recognized, with the northern spring and summer being the cloudiest periods on Mars. We interpret some of the identified cloudy zones as the southern and northern solstice season upwelling branches of the Hadley cell, although these were shifted 15 degrees-20 degrees southward from model predictions. Additionally, the transition between the two branches occurred later in time than in the model predictions. We observed the extension of the north polar hood below 60 degrees N in longitudes 120 degrees-200 degrees. We did not find evidence for a south polar hood north of 60 degrees S nor any evidence for interannual variability within our limited data set. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. RP Tamppari, LK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 54 TC 32 Z9 32 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD FEB 25 PY 2000 VL 105 IS E2 BP 4087 EP 4107 DI 10.1029/1999JE001133 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 287LG UT WOS:000085506900001 ER PT J AU Clark, PE McFadden, LA AF Clark, PE McFadden, LA TI New results and implications for lunar crustal iron distribution using sensor data fusion techniques SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INFRARED SPECTRAL REFLECTANCE; GAMMA-RAY SPECTROMETER; SOLAR-SYSTEM; MOON; SURFACE; CLEMENTINE; PROSPECTOR; OLIVINE; ABUNDANCES; PYROXENES AB Remote measurements of the Moon have provided iron maps, and thus essential constraints for models of lunar crustal formation and mare basalt petrogenesis. A bulk crustal iron map was produced for the equatorial region from Apollo gamma-ray (AGR) spectrometer measurements, and a global iron variation map from recent Clementine spectral reflectance (CSR) measurements. Both iron maps show bimodal distribution, but have significantly different peak values and variations. In this paper, CSR data have been recalibrated to pyroxene in lunar landing site soils. A residual iron map is derived from the difference between AGR (bulk) and recalibrated CSR (pyroxene) iron abundances. The most likely interpretation is that the residual represents ferrous iron in olivine. This residual iron is anticorrelated to basin age, with older basins containing less olivine, suggesting segregation of basin basalt sources from a progressively fractionating underlying source region at the time of basin formation. Results presented here provide a quantitative basis for (1) establishing the relationship between direct geochemical (gamma-ray, X-ray) and mineralogical (near-IR) remote sensing data sets using sensor data fusion techniques to allow (2) simultaneous determination of elemental and mineralogical component distribution on remote targets and (3) meaningful interpretation of orbital and ground-based spectral reflectance measurements. When calibrated data from the Lunar Prospector mission are available, mapping of bulk crustal iron and iron-bearing soil components will be possible for the entire Moon. Similar analyses for data from the Near Earth Asteroid Rendezvous (NEAR) mission to asteroid 433 Eros will constrain models of asteroid formation. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Clark, PE (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 961, Greenbelt, MD 20771 USA. EM yslpc@lpvax.gsfc.nasa.gov; mcfadden@astro.umd.edu RI McFadden, Lucy-Ann/I-4902-2013 OI McFadden, Lucy-Ann/0000-0002-0537-9975 NR 100 TC 14 Z9 14 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD FEB 25 PY 2000 VL 105 IS E2 BP 4291 EP 4316 DI 10.1029/1999JE001078 PG 26 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 287LG UT WOS:000085506900015 ER PT J AU Song, LM Mihara, T Matsuoka, M Negoro, H Corbet, R AF Song, LM Mihara, T Matsuoka, M Negoro, H Corbet, R TI ASCA observations of RX J1838.4-0301 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE pulsars : individual (RX J1838.4-0301); stars : magnetic fields; stars : neutron; supernova remnants ID X-RAY PULSAR; SUPERNOVA REMNANT; EMISSION; STARS AB The results of ASCA observations of RX J1838.4-0301 are presented. The source was found to be faint and there was no obvious X-ray flare during the ASCA observation. No evidence for pulsations was found near to the 5.45 s period previously reported from ROSAT observations. The source energy spectrum cannot be fitted well with either a single-component power law, thermal bremsstrahlung, or blackbody emission model, while a variety of two component models do give acceptable fits. The flux which we derive is consistent with that measured in the quiescent state with ROSAT. On the basis of the ROSAT and ASCA results, we suggest that RX J1838.4-0301 may be a transient source in which the quiescent state has a fairly constant flux level. However, our results do not yet enable a clear determination of whether this source is an anomalous X-ray pulsar or some other type of object. C1 Inst High Energy Phys, Beijing 100039, Peoples R China. Inst Phys & Chem Res, Wako, Saitama 3510198, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Inst High Energy Phys, Beijing 100039, Peoples R China. EM song@crab.riken.go.jp RI Mihara, Tatehiro/C-5536-2017 OI Mihara, Tatehiro/0000-0002-6337-7943 NR 19 TC 3 Z9 4 U1 1 U2 1 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD FEB 25 PY 2000 VL 52 IS 1 BP 181 EP 184 DI 10.1093/pasj/52.1.181 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 292HK UT WOS:000085788400023 ER PT J AU Singer, BA Brentner, KS Lockard, DP Lilley, GM AF Singer, BA Brentner, KS Lockard, DP Lilley, GM TI Simulation of acoustic scattering from a trailing edge SO JOURNAL OF SOUND AND VIBRATION LA English DT Article; Proceedings Paper CT 37th Aerospace Science Meeting and Exhibit CY JAN 01-14, 1999 CL RENO, NV SP AIAA ID NOISE; PREDICTION AB Three model problems were examined to assess the difficulties involved in using a hybrid scheme coupling flow computation with the Ffowcs Williams and Hawkings equation to predict the noise generated by vortices passing over a sharp edge. The results indicate that the Ffowcs Williams and Hawkings equation correctly propagates the acoustic signals when provided with accurate flow information on the integration surface. The most difficult of the model problems investigated flow over a two-dimensional, thin NACA airfoil with a bluff-body vortex generator positioned at 98% chord. Vortices rolled up downstream of the bluff body. The shed vortices possessed similarities to large coherent eddies in boundary layers in that they interacted and occasionally paired as they convected past the sharp trailing edge of the airfoil. The calculations showed acoustic waves emanating from the airfoil trailing edge. Acoustic directivity and Mach number scaling were obtained. (C) 2000 Academic Press. C1 NASA, Langley Res Ctr, Div Fluid Mech & Acoust, Hampton, VA 23681 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Singer, BA (reprint author), NASA, Langley Res Ctr, Div Fluid Mech & Acoust, Hampton, VA 23681 USA. NR 24 TC 33 Z9 33 U1 0 U2 4 PU ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X EI 1095-8568 J9 J SOUND VIB JI J. Sound Vibr. PD FEB 24 PY 2000 VL 230 IS 3 BP 541 EP 560 DI 10.1006/jsvi.1999.2628 PG 20 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 292BF UT WOS:000085773700005 ER PT J AU Ohsaka, K Trinh, EH AF Ohsaka, K Trinh, EH TI Three-lobed shape bifurcation of rotating liquid drops SO PHYSICAL REVIEW LETTERS LA English DT Article ID EQUILIBRIUM; SPACE AB The evolution of axisymmetric equilibrium shapes of a rigidly rotating liquid drop can be extended beyond the 2-lobed shape bifurcation point if the rotating drop is driven in the n = 2 axisymmetric shape oscillation (perturbation), where n is the mode of oscillation. A reason for the extended stability of the perturbed rotating drop is that the inertia of the driven axisymmetric shape oscillation suppresses growth of a natural nonaxisymmetric shape fluctuation which leads to the 2-lobed shape bifurcation. The axisymmetric shape of the drop eventually bifurcates into either a 2- or a 3-lobed shape at a higher bifurcation point which is asserted to be the 3-lobed shape bifurcation point. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ohsaka, K (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 13 TC 25 Z9 25 U1 0 U2 3 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD FEB 21 PY 2000 VL 84 IS 8 BP 1700 EP 1703 DI 10.1103/PhysRevLett.84.1700 PG 4 WC Physics, Multidisciplinary SC Physics GA 285HK UT WOS:000085383500016 ER PT J AU Mishchenko, MI AF Mishchenko, MI TI Calculation of the amplitude matrix for a nonspherical particle in a fixed orientation SO APPLIED OPTICS LA English DT Article ID LIGHT-SCATTERING AB General equations are derived for computing the amplitude matrix for a nonspherical particle in an arbitrary orientation and for arbitrary illumination and scattering directions with respect to the laboratory reference frame, provided that the scattering problem can be solved with respect to the particle reference frame. These equations are used along with the T-matrix method to provide benchmark results for homogeneous, dielectric, rotationaly symmetric particles. The computer code is publicly available on the World-Wide Web at http://www.giss.nasa.gov/similar to crimm. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Mishchenko, MI (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM crmim@giss.nasa.gov RI Mishchenko, Michael/D-4426-2012 NR 14 TC 164 Z9 165 U1 2 U2 12 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD FEB 20 PY 2000 VL 39 IS 6 BP 1026 EP 1031 DI 10.1364/AO.39.001026 PG 6 WC Optics SC Optics GA 285XC UT WOS:000085412800019 PM 18337981 ER PT J AU Uchida, KI Sellgren, K Werner, MW Houdashelt, ML AF Uchida, KI Sellgren, K Werner, MW Houdashelt, ML TI Infrared Space Observatory mid-infrared spectra of reflection nebulae SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; infrared : ISM; lines and bands; reflection nebulae ID POLYCYCLIC AROMATIC-HYDROCARBONS; CARBONACEOUS COMPOSITE QCC; PROTO-PLANETARY-NEBULAE; EMISSION BANDS; INTERSTELLAR DUST; MICRON EMISSION; SMALL GRAINS; ABSORPTION FEATURES; MONOCEROS R2/IRS-3; IRAS SOURCES AB We present 5-15 mu m imaging spectroscopy of the reflection nebulae vdB 17 (NGC 1333), vdB 59 (NGC 2068), vdB 101, vdB 111, vdB 133, and vdB 135, obtained with the infrared camera and circular variable filter wheel on the Infrared Space Observatory (ISO). These nebulae are illuminated by stars with T-eff = 3,600-19,000 K, implying UV (lambda < 400 nm) to total stellar flux ratios of F-(lambda<400nm)/F-total = 0.01-0.87. We detect the infrared emission features (IEFs) at 6.2, 7.7, 8.6, 11.3, and 12.7 mu m, broad emission features at 6-9 mu m and 11-13 mu m, and 5-15 mu m continuum emission, from the interstellar medium in vdB 17, vdB 59, and vdB 133 (F-(lambda<400nm)/F-total = 0.22-0.87), and place upper limits on the emission from the interstellar medium in vdB 101, vdB 111, and vdB 135 (F-(lambda<400nm)/F-total = 0.01-0.20). Our goal is to test predictions of models attributing the IEFs to polycyclic aromatic hydrocarbons (PAHs). Interstellar models predict PAHs change from singly ionized to neutral as the UV intensity, G(0), decreases. The ratio of PAH emission at 6-10 mu m to PAH emission at 10-14 pm is expected to be 10 times higher in ionized than in neutral PAHs. We observe no spectroscopic differences with varying T-eff. We analyze the spectra of vdB 17 and vdB 59 as a function of distance from the star to see how the spectra depend on G(0) within each source. The only quantitative difference we find is a broadening of the 7.7 mu m IEF at G(0) = 20-60 within vdB 17. We observe only a 40% change in the 6-10 pm to 10-14 pm flux ratio over G(0) = 20-6 x 10(4). C1 Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Uchida, KI (reprint author), Cornell Univ, 108 Space Sci Bldg, Ithaca, NY 14853 USA. NR 97 TC 67 Z9 67 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2000 VL 530 IS 2 BP 817 EP 833 DI 10.1086/308379 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 297BW UT WOS:000086062500021 ER PT J AU Reiner, MJ Karlicky, M Jiricka, K Aurass, H Mann, G Kaiser, ML AF Reiner, MJ Karlicky, M Jiricka, K Aurass, H Mann, G Kaiser, ML TI On the solar origin of complex type III-like radio bursts observed at and below 1 Mhz SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : flares; Sun : particle emission; Sun : radio radiation ID ELECTRON ACCELERATION; CORONA; EMISSION; WAVES; FLARE; SITES AB By simultaneously analyzing decimetric, metric, and hectometric radio observations, we provide evidence that a class of hectometric type III-like radio events are associated with electrons accelerated during the primary flare energy release process. We do this by demonstrating that there is a good temporal correspondence between the hectometric and decimetric radio emissions that are believed to involve the acceleration of electrons in deep layers of the solar atmosphere at heights estimated to be from 10,000 to 30,000 km (0.014 to 0.043 R.). This class of hectometric type III-like events may have simple or complex intensity-time profiles. When they have complex profiles of long duration, the decimeter emissions also have complex long-duration profiles. In this latter case they are also often associated with metric type II radio bursts and coronal mass ejections (CMEs). However, we argue on the basis of the observations that the hectometric radio emissions are not necessarily associated with the metric phenomena. Specifically, they are not likely generated by a secondary acceleration process associated with the shock generating a metric type II burst or with a shock driven ahead of the CME despite the fact that the hectometric emission time profiles would (erroneously) be morphologically classified as shock-accelerated (SA) events. C1 Raytheon Informat Technol & Sci Serv, Lanham, MD 20706 USA. Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov, Czech Republic. Astrophys Inst Potsdam, D-14482 Potsdam, Germany. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Reiner, MJ (reprint author), Raytheon Informat Technol & Sci Serv, 4400 Forbes Blvd, Lanham, MD 20706 USA. RI Karlicky, Marian/G-9023-2014 NR 36 TC 47 Z9 47 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2000 VL 530 IS 2 BP 1049 EP 1060 DI 10.1086/308394 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 297BW UT WOS:000086062500041 ER PT J AU Davidson, K Ishibashi, K Gull, TR Humphreys, RM Smith, N AF Davidson, K Ishibashi, K Gull, TR Humphreys, RM Smith, N TI eta Carinae: Testing a binary orbit model with the Hubble Space Telescope/Space Telescope Imaging Spectrograph SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : individual (eta Carinae) AB Ground-based spectroscopy of eta Car shows periodic changes in some emission-line wavelengths. These variations have been cited as strong evidence that this object is a 5.5 yr binary system and have been used to produce specific orbit models. High spatial resolution data obtained with the Hubble Space Telescope/Space Telescope Imaging Spectrograph, however, do not confirm the predicted velocity behavior; therefore, the published orbit models are almost certainly invalid. Wavelength fluctuations seen at ground-based spatial resolution most likely result from other effects, which we describe. If this object is a binary system (which has not been proven), then the parameters of the secondary star and of the orbit remain largely unknown. C1 Univ Minnesota, Dept Astron, Minneapolis, MN 55455 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Davidson, K (reprint author), Univ Minnesota, Dept Astron, 116 Church St SE, Minneapolis, MN 55455 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 17 TC 41 Z9 41 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2000 VL 530 IS 2 BP L107 EP L110 DI 10.1086/312502 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 297BX UT WOS:000086062600014 ER PT J AU Stothers, RB AF Stothers, RB TI Does turbulence in the iron convection zone cause the massive outbursts of eta Carinae? SO ASTROPHYSICAL JOURNAL LA English DT Article DE convection; stars : individual (eta Carinae); stars : oscillations; stars : variables : other (luminous blue variables); turbulence ID STARS; RATES; SPECTROSCOPY; EVOLUTION AB Taken at face value, the observed properties of the central object in eta Carinae suggest a very massive, hot main-sequence star, only slightly evolved. If this is so, the star's extraordinarily high steady rate of mass loss must dynamically perturb its outer envelope down to the iron convection zone, in which the kinetic energy associated with turbulent convection can be directly fed into mass ejection. Runaway mass loss, triggered by either internal (pulsational, rotational) or external (tidal) forcing, would produce a secular oscillation of the outer envelope. In either case, the oscillation is potentially able to account for the observed similar to 5 yr cycles of visual outbursts in eta Car, including the giant eruption of 1843. C1 NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. RP Stothers, RB (reprint author), NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. NR 37 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2000 VL 530 IS 2 BP L103 EP L106 DI 10.1086/312500 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 297BX UT WOS:000086062600013 ER PT J AU Zhang, SN Cui, W Chen, W Yao, YS Zhang, XL Sun, XJ Wu, XB Xu, HG AF Zhang, SN Cui, W Chen, W Yao, YS Zhang, XL Sun, XJ Wu, XB Xu, HG TI Three-layered atmospheric structure in accretion disks around stellar-mass black holes SO SCIENCE LA English DT Article ID HIGH-ENERGY OBSERVATIONS; TRANSIENT GRO J1655-40; X-RAY BINARIES; SUPERLUMINAL SOURCE; SEYFERT-GALAXIES; JETS; COMPTONIZATION; MODEL AB Modeling of the x-ray spectra of the Galactic superluminal jet sources GRS 1975 + 105 and GRO J7655-40 reveals a three-layered atmospheric structure in the inner region of their accretion disks. Above the cold and optically thick disk with a temperature of 0.2 to 0.5 kiloelectron volts, there is a warm Layer with a temperature of 1.0 to 1.5 kiloelectron volts and an optical depth around 10. Sometimes there is also a much hotter, optically thin corona above the warm layer, with a temperature of 100 kiloelectron volts or higher and an optical depth around unity. The structural similarity between the accretion disks and the solar atmosphere suggests that similar physical processes may be operating in these different systems. C1 Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NASA, Space Sci Lab, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Chinese Acad Sci, Beijing Astron Observ, Beijing 100012, Peoples R China. Shanghai Jiao Tong Univ, Dept Appl Phys, Inst Space & Astrophys, Shanghai 200030, Peoples R China. RP Zhang, SN (reprint author), Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. EM zhangsn@email.uah.edu OI Cui, Wei/0000-0002-6324-5772 NR 35 TC 44 Z9 46 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD FEB 18 PY 2000 VL 287 IS 5456 BP 1239 EP 1241 DI 10.1126/science.287.5456.1239 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 286KG UT WOS:000085444700042 ER PT J AU Bamber, JL Vaughan, DG Joughin, I AF Bamber, JL Vaughan, DG Joughin, I TI Widespread complex flow in the interior of the Antarctic ice sheet SO SCIENCE LA English DT Article ID WEST ANTARCTICA; MASS-BALANCE; DYNAMICS; STREAMS; GREENLAND; IMAGERY; MODEL AB It has been suggested that as much as 90% of the discharge from the Antarctic Ice Sheet is drained through a small number of fast-moving ice streams and outlet glaciers fed by relatively stable and inactive catchment areas. Here, evidence obtained from balance velocity estimates suggests that each major drainage basin is fed by complex systems of tributaries that penetrate up to 1000 kilometers from the grounding line into the interior of the ice sheet. This finding has important consequences for the modeled or estimated dynamic response time of past and present ice sheets to climate forcing. C1 Univ Bristol, Sch Geog Sci, Bristol Glaciol Ctr, Bristol BS8 1SS, Avon, England. British Antarctic Survey High Cross, Cambridge CB3 0ET, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bamber, JL (reprint author), Univ Bristol, Sch Geog Sci, Bristol Glaciol Ctr, Univ Rd, Bristol BS8 1SS, Avon, England. EM j.l.bamber@bristol.ac.uk RI Joughin, Ian/A-2998-2008; Vaughan, David/C-8348-2011; Bamber, Jonathan/C-7608-2011 OI Joughin, Ian/0000-0001-6229-679X; Bamber, Jonathan/0000-0002-2280-2819 NR 20 TC 208 Z9 213 U1 3 U2 26 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD FEB 18 PY 2000 VL 287 IS 5456 BP 1248 EP 1250 DI 10.1126/science.287.5456.1248 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 286KG UT WOS:000085444700045 ER PT J AU Farassat, F AF Farassat, F TI The integration of delta '' (f) in a multi-dimensional space SO JOURNAL OF SOUND AND VIBRATION LA English DT Letter C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Farassat, F (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 3 TC 3 Z9 4 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD FEB 17 PY 2000 VL 230 IS 2 BP 460 EP 462 DI 10.1006/jsvi.1999.2580 PG 3 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 286GK UT WOS:000085435100016 ER PT J AU Thompson, AM Singh, HB Schlager, H AF Thompson, AM Singh, HB Schlager, H TI Introduction to special section: Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) and Pollution from Aircraft Emissions in the North Atlantic Flight Corridor (POLINAT 2) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. DLR, Inst Phys Atmosphare, D-82234 Wessling, Germany. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. EM thompson@garor1.gsfc.nasa.gov RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 23 TC 16 Z9 16 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3595 EP 3603 DI 10.1029/2000JD900012 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000007 ER PT J AU Fuelberg, HE Hannan, JR van Velthoven, PFJ Browell, EV Bieberbach, G Knabb, RD Gregory, GL Pickering, KE Selkirk, HB AF Fuelberg, HE Hannan, JR van Velthoven, PFJ Browell, EV Bieberbach, G Knabb, RD Gregory, GL Pickering, KE Selkirk, HB TI A meteorological overview of the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) period SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPICAL SOUTH-ATLANTIC; DISTRIBUTIONS; TRACE; AIR; TRAJECTORIES; TRANSPORT; AEROSOLS; AFRICA; LIDAR; OCEAN AB Meteorological conditions are described during NASA's Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) that was conducted over the North Atlantic Flight Corridor (NAFC) during October and November 1997 to study the impact of aircraft emissions on atmospheric concentrations of NO, and ozone. The SONEX period exhibited frequent closed cyclones and anticyclones, as well as high-amplitude troughs and ridges. These flow patterns often caused aircraft exhaust from the NAFC to follow broad looping north-south trajectories, instead of more easterly routes that would have occurred if the flow had been more zonal. Mean meteorological conditions during SONEX include a pronounced long wave trough over the East Coast of the United States, as well as weaker low pressure over middle-latitude portions of the Atlantic Ocean. Conversely, a well-developed ridge was apparent over the North Atlantic near Iceland. Cloudiness exceeded climatology off the East Coast and the subtropical North Atlantic, with abundant lightning in these regions. There was less than average cloud cover over the middle latitudes between Newfoundland and central Europe. The tropopause was higher than climatology over much of the SONEX region, and the jet stream was located north of its typical position. These circulation features during SONEX are consistent with typical year-to-year variations. Meteorological conditions during individual SONEX flights also are described. Upper tropospheric flow patterns, 5-day backward trajectories from the flight tracks, tropopause heights, lightning data, and differential absorption lidar ozone imagery are employed. Effects of aircraft were observed on numerous flights. Stratospheric conditions were encountered during many flights, sometimes because the DC-8 passed through a tropopause fold. SONEX flight tracks frequently were downwind of regions of lightning, especially during flights from Banger and the Azores. Finally, trajectories indicated that continental pollution signatures observed during some flights had originated over the United States. C1 Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Maryland, Joint Ctr Earth Syst Sci, College Pk, MD 20742 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Royal Netherlands Meteorol Inst, NL-3730 AE De Bilt, Netherlands. RP Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. EM fuelberg@met.fsu.edu RI Pickering, Kenneth/E-6274-2012; Selkirk, Henry/H-2021-2012 NR 32 TC 21 Z9 21 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3633 EP 3651 DI 10.1029/1999JD900917 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000009 ER PT J AU Koike, M Kondo, Y Ikeda, H Gregory, GL Anderson, BE Sachse, GW Blake, DR Liu, SC Singh, HB Thompson, AM Kita, K Zhao, Y Sugita, T Shetter, RE Toriyama, N AF Koike, M Kondo, Y Ikeda, H Gregory, GL Anderson, BE Sachse, GW Blake, DR Liu, SC Singh, HB Thompson, AM Kita, K Zhao, Y Sugita, T Shetter, RE Toriyama, N TI Impact of aircraft emissions on reactive nitrogen over the North Atlantic Flight Corridor region SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPOSPHERE; STRATOSPHERE AB The impact of aircraft emissions on reactive nitrogen in the upper troposphere (UT) and lowermost stratosphere (LS) was estimated using the NOy-O-3 correlation obtained during the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) carried out over the U.S. continent and North Atlantic Flight Corridor (NAFC) region in October and November 1997. To evaluate the large-scale impact, we made a reference NOy-O-3 relationship in air masses, upon which aircraft emissions were considered to have little impact. For this purpose, the integrated input of NO, from aircraft into an air mass along a 10-day back trajectory (Delta NOy) was calculated based on the Abatement of Nuisance Caused by Air Traffic/European Commission (ANCAT/EC2) emission inventory. The excess NOy (dNO(y)) was calculated from the observed NO, and the reference NOy-O-3 relationship. As a result, a weak positive correlation was found between the dNO(y) and Delta NOy and dNO(y) and NOx/NOy values, while no positive correlation between the dNO(y) and CO values was found suggesting that dNO(y) values can be used as a measure of the NOx input from aircraft emissions. The excess NOy values calculated from another NOy-O-3 reference relationship made using in situ condensation nuclei data also agreed with these dNO(y) values, within the uncertainties. At the NAFC region (45 degrees N-60 degrees N) the median value of dNO(y) in the troposphere increased with altitude above 9 km and reached 70 parts per trillion by volume (pptv) (20% of NOy) at 11 km. The excess NOx was estimated to be about half of the dNO(y) values, corresponding to 30% of the observed NOx level. Higher dNO(y), values were generally found in air masses where O-3 = 75-125 ppbv, suggesting a more pronounced effect around the tropopause. The median value of dNO(y) in the stratosphere at the NAFC region at 8.5-11.5 km was about 120 pptv. The higher dNO(y) values in the LS were probably due to the accumulated effect of aircraft emissions, given the long residence time of affected air in the LS. Similar dNO(y) values were also obtained in air masses sampled over the U.S. continent. C1 Nagoya Univ, Solar Terr Environm Lab, Aichi 4428507, Japan. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. Univ Tokyo, Fac Sci, Dept Earth & Planetary Phys, Bunkyo Ku, Tokyo 113, Japan. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. Natl Ctr Atmospher Res, Boulder, CO 80303 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Natl Inst Environm Studies, Tsukuba, Ibaraki 3050053, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Nagoya Univ, Solar Terr Environm Lab, Aichi 4428507, Japan. EM koike@stelab.nagoya-u.ac.jp; kondo@stelab.nagoya-u.ac.jp; hibiki@stelab.nagoya-u.ac.jp; g.l.gregory@larc.nasa.gov; b.e.anderson@larc.nasa.gov; g.w.sachse@larc.nasa.gov; drblake@uci.edu; shaw.liu@eas.gatech.edu; hsingh@mail.arc.nasa.gov; thompson@gator1.gsfc.nasa.gov; kita@grl.s.u-tokyo.ac.jp; yzhao@stelab.nagoya-u.ac.jp; tsugita@nies.go.jp; toriyama@stelab.nagoya-u.ac.jp RI Koike, Makoto/F-4366-2011; Kondo, Yutaka/D-1459-2012; Thompson, Anne /C-3649-2014; OI Thompson, Anne /0000-0002-7829-0920; Sugita, Takafumi/0000-0002-0508-7040 NR 28 TC 19 Z9 19 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3665 EP 3677 DI 10.1029/1999JD901013 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000011 ER PT J AU Jeker, DP Pfister, L Thompson, AM Brunner, D Boccippio, DJ Pickering, KE Wernli, H Kondo, Y Staehelin, J AF Jeker, DP Pfister, L Thompson, AM Brunner, D Boccippio, DJ Pickering, KE Wernli, H Kondo, Y Staehelin, J TI Measurements of nitrogen oxides at the tropopause: Attribution to convection and correlation with lightning SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERE-TROPOSPHERE EXCHANGE; DETECTION NETWORK; SULFUR-DIOXIDE; UNITED-STATES; NITRIC-OXIDE; NOX; OZONE; AIRCRAFT; AIR; THUNDERSTORMS AB NOx (NO and NO2) and ozone were measured on 98 flights during August to November 1997 in the framework of the projects Pollution From Aircraft Emissions in the North Atlantic Flight Corridor (POLINAT 2) and Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX), The fully automated measurement system Nitrogen Oxides and Ozone Along Air Routes (NOXAR) was permanently installed aboard an inservice Swissair B-747 airliner operating in the North Atlantic Flight Corridor. Below the tropopause, predominantly over the U.S. east coast, the patchy occurrence of NOx enhancements up to 3000 parts per trillion by volume (pptv) was observed frequently and led to a lognormal probability density function of NOx These plumes extend over several hundred kilometers. In three case studies the origin of such plumes was investigated using back trajectories, satellite infrared images, and lightning observations from the U.S. National Lightning Detection Network (NLDN) and the Optical Transient Detector (OTD) satellite instrument. In the case of frontal activity above the continental United States, the location of NOx plumes was explained with maps of convective influence. In another case, NOx seems to have been produced by lightning in a marine thunderstorm over the eastern Atlantic. Lightning activity triggered over the warm Gulf Stream is found to be an important source for the regional upper tropospheric NOx budget, at least for the time period considered. With a method that we call "lightning tracing" we show for the first time that (in some cases) the number of lightning flashes, accumulated along back trajectories, was proportional to the NOx concentrations observed several hundred kilometers downwind of the anvil outflows. We suggest that mixing processes in convective clouds reduce the initially highly heterogeneous NOx field rapidly, but that following this phase, the structure of large-scale plumes remains stable over relatively long periods of time (as they decay). C1 Swiss Fed Inst Technol, Inst Atmospher Sci, Zurich, Switzerland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Royal Netherlands Meteorol Inst, KNMI, Sect Atmospher Composit, NL-3730 AE De Bilt, Netherlands. NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. Univ Maryland, Dept Meteorol, Joint Ctr Earth Syst Sci, College Pk, MD 20742 USA. Nagoya Univ, Solar Terr Environm Lab, Aichi, Japan. RP Swiss Fed Inst Technol, Inst Atmospher Sci, Zurich, Switzerland. EM jeker@atmos.umnw.ethz.ch; pfister@mindego.arc.nasa.gov; thompson@gator1.gsfc.nasa.gov; brunner@knmi.nl; dennis.boccippio@msfc.nasa.gov; pickerin@metosrv2.umd.edu; henry@atmos.umnw.ethz.ch; kondo@stelab.nagoya-u.ac.jp; staehelin@atmos.umnw.ethz.ch RI Brunner, Dominik/A-1255-2009; Kondo, Yutaka/D-1459-2012; Pickering, Kenneth/E-6274-2012; Thompson, Anne /C-3649-2014 OI Brunner, Dominik/0000-0002-4007-6902; Thompson, Anne /0000-0002-7829-0920 NR 61 TC 31 Z9 34 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3679 EP 3700 DI 10.1029/1999JD901053 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000012 ER PT J AU Pueschel, RF Verma, S Rohatschek, H Ferry, GV Boiadjieva, N Howard, SD Strawa, AW AF Pueschel, RF Verma, S Rohatschek, H Ferry, GV Boiadjieva, N Howard, SD Strawa, AW TI Vertical transport of anthropogenic soot aerosol into the middle atmosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MESOSPHERE SUMMER ECHOES; POLAR MESOSPHERE; SOUTHERN-HEMISPHERE; PHOTOPHORETIC FORCES; FRACTAL DIMENSION; DUST PARTICLES; CLOUDS; STRATOSPHERE; LEVITATION; SMOKE AB Gravito-photophoresis, a sunlight-induced force acting on particles which are geometrically asymmetric and which have uneven surface distribution of thermal accommodation coefficients, explains vertical transport of fractal soot aerosol emitted by aircraft in conventional flight corridors (10-12 km altitude) into the mesosphere (>80 km altitude). While direct optical effects of this aerosol appeal nonsignificant, it is conceivable that they play a role in mesospheric physics by providing nuclei for polar mesospheric cloud formation and by affecting the ionization of the mesosphere to contribute to polar mesospheric summer echoes. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. Symtek Corp Inc, Arlington, VA 22202 USA. Johannes Kepler Univ Linz, A-4040 Linz, Austria. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. RP NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. EM rpueschel@mail.arc.nasa.gov NR 56 TC 35 Z9 40 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3727 EP 3736 DI 10.1029/1999JD900505 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000016 ER PT J AU Ovarlez, J van Velthoven, P Sachse, G Vay, S Schlager, H Ovarlez, H AF Ovarlez, J van Velthoven, P Sachse, G Vay, S Schlager, H Ovarlez, H TI Comparison of water vapor measurements from POLINAT 2 with ECMWF analyses in high-humidity conditions SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RELATIVE-HUMIDITY; ICE NUCLEATION; CIRRUS; AIRCRAFT; CLOUDS; ASSIMILATION; TEMPERATURE; SENSITIVITY; CLIMATE AB During the Pollution From Aircraft in the North Atlantic Flight Corridor (POLINAT 2) experiment, water vapor content was measured during 12 flights of the Deutsches Zentrum fuer Luft und Raumfahrt Falcon research aircraft by means of a frost-point hygrometer. The last three flights were coordinated with the flights of the NASA DCS aircraft, taking part in the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX). The measurements were generally performed in high-humidity and cloudy environments. Synthesized profiles of humidity and cloud cover along the flight tracks were retrieved from the European Centre for Medium-Range Weather Forecasts analyses. It is shown that the measurements of supersaturation are generally correlated to the occurrence of clouds as indicated by the model cloud cover product. However, there are large discrepancies between the mixing ratio from the analyses and the measurements: the model underestimates the water vapor content. Some reasons for this underestimation are put forward, and the consequences for the investigation of the occurrence of contrail formation and persistence, when using such analyses, are pointed out. C1 Ecole Polytech, CNRS, Meteorol Dynam Lab, F-91128 Palaiseau, France. NASA, Langley Res Ctr, Hampton, VA 23681 USA. DLR, Inst Phys Atmosphare, D-82230 Wessling, Germany. Royal Netherlands Meteorol Inst, NL-3730 AE De Bilt, Netherlands. RP Ecole Polytech, CNRS, Meteorol Dynam Lab, F-91128 Palaiseau, France. EM joelle.ovarlez@polytechnique.fr NR 23 TC 40 Z9 40 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3737 EP 3744 DI 10.1029/1999JD900954 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000017 ER PT J AU Vay, SA Anderson, BE Jensen, EJ Sachse, GW Ovarlez, J Gregory, GL Nolf, SR Podolske, JR Slate, TA Sorenson, CE AF Vay, SA Anderson, BE Jensen, EJ Sachse, GW Ovarlez, J Gregory, GL Nolf, SR Podolske, JR Slate, TA Sorenson, CE TI Tropospheric water vapor measurements over the North Atlantic during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HYGROMETER; EMISSIONS; CONTRAILS; SUCCESS; CLOUD AB Fast-response tunable diode laser measurements of water vapor were made over the North Atlantic during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) conducted in the fall of 1997. Resulting water vapor mixing ratios, in conjunction with air temperature and pressure measurements obtained by the DC-8's Data Acquisition and Distribution System (DADS), were used to calculate the prevalence of ice-saturated conditions (relative humidity with respect to ice > 100% or frost saturation) in the upper troposphere over the SONEX sampling region. Additionally, Appleman theory was applied to the data to determine the subset of ice-saturated regions which would support formation of contrails. Results suggest that studies to determine the potential climate or radiative impact of contrails and aviation-induced cirrus clouds should not only consider the climatology of frost-saturated regions, but should also address whether ambient conditions can support contrail formation within these regions. A separate discussion within the paper describes an in-flight intercomparison between the SONEX diode laser hygrometer and the Pollution From Aircraft Emissions in the North Atlantic Flight Corridor (POLINAT 2) cryogenic hygrometer and shows that the instruments perform to within their stated accuracies (similar to 10%) over a range of mixing ratios and altitudes. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Comp Sci Corp, Hampton, VA USA. Ecole Polytech, CNRS, Meteorol Dynam Lab, F-91128 Palaiseau, France. Fed Data Corp, Hampton, VA USA. NASA, Dryden Flight Res Ctr, Edwards AFB, CA 93523 USA. RP NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. EM s.a.vay@larc.nasa.gov NR 31 TC 23 Z9 23 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3745 EP 3755 DI 10.1029/1999JD901019 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000018 ER PT J AU Grant, WB Browell, EV Butler, CF Fenn, MA Clayton, MB Hannan, JR Fuelberg, HE Blake, DR Blake, NJ Gregory, GL Heikes, BG Sachse, GW Singh, HB Snow, J Talbot, RW AF Grant, WB Browell, EV Butler, CF Fenn, MA Clayton, MB Hannan, JR Fuelberg, HE Blake, DR Blake, NJ Gregory, GL Heikes, BG Sachse, GW Singh, HB Snow, J Talbot, RW TI A case study of transport of tropical marine boundary layer and lower tropospheric air masses to the northern midlatitude upper troposphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AIRCRAFT MEASUREMENTS; POTENTIAL VORTICITY; INSITU MEASUREMENTS; PACIFIC-OCEAN; OZONE; TROPOPAUSE; LIDAR; RANGE; FLUX AB Low-ozone (< 20 ppbv) air masses were observed in the upper troposphere in northern midlatitudes over the eastern United States and the North Atlantic Ocean on several occasions in October 1997 during the NASA Subsonic Assessment, Ozone and Nitrogen Oxide Experiment (SONEX) mission. Three cases of low-ozone air masses were shown to have originated in the tropical Pacific marine boundary layer or lower troposphere and advected poleward along a warm conveyor belt during a synoptic-scale disturbance. The tropopause was elevated in the region with the low-ozone air mass. Stratospheric intrusions accompanied the disturbances. On the basis of storm track and stratospheric intrusion climatologies, such events appear to be more frequent from September through March than the rest of the year. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Calif Irvine, Dept Chem, Irvine, CA 92717 USA. Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. Univ Rhode Isl, Grad Sch Oceanog, Ctr Atmospher Chem Studies, Narragansett, RI 02882 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA. RP NASA, Langley Res Ctr, Hampton, VA 23681 USA. EM w.b.grant@larc.nasa.gov RI Grant, William/B-8311-2009 OI Grant, William/0000-0002-1439-3285 NR 43 TC 28 Z9 28 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3757 EP 3769 DI 10.1029/1999JD901022 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000019 ER PT J AU Faloona, I Tan, D Brune, WH Jaegle, L Jacob, DJ Kondo, Y Koike, M Chatfield, R Pueschel, R Ferry, G Sachse, G Vay, S Anderson, B Hannon, J Fuelberg, H AF Faloona, I Tan, D Brune, WH Jaegle, L Jacob, DJ Kondo, Y Koike, M Chatfield, R Pueschel, R Ferry, G Sachse, G Vay, S Anderson, B Hannon, J Fuelberg, H TI Observations of HOx and its relationship with NOx in the upper troposphere during SONEX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID IN-SITU MEASUREMENTS; OZONE PRODUCTION; OH; STRATOSPHERE; PHOTOCHEMISTRY; ATMOSPHERE; CHEMISTRY; PEROXIDES; SUCCESS; ACETONE AB Simultaneous measurements of the oxides of hydrogen and nitrogen made during the NASA Subsonic Assessment, Ozone and Nitrogen Oxide Experiment (SONEX) afforded an opportunity to study the coupling between these two important families throughout the free troposphere and lowermost stratosphere. Moreover, the suite of measurements made during the campaign was unprecedented in its completeness, thus providing a uniquely detailed picture of the radical photochemistry that drives oxidation and ozone production in this part of the atmosphere. On average, observed hydrogen oxides (HOx = OH + HO2) agree well with both instantaneous and diel steady-state models; however, there is a persistent deviation of the observations that correlates with the abundance of nitrogen oxides (NOx = NO + NO2) in the sampled air mass. Specifically, the observed HOx tends to exceed the model predictions in the presence of high NOx concentrations, by as much as a factor of 5 (>500 pptv NOx), and is sometimes as little as half that expected by steady state at lower NOx levels. While many possibilities for these discrepancies are discussed, it is argued that an instrumental artifact is not probable and that the discrepancy may bespeak a shortcoming of our understanding of HOx chemistry. The consistently elevated HOx in the presence of elevated NOx leads directly to greater ozone production than expected, thereby extending the NOx-limited regime of the upper troposphere. These results could thus have bearing on the predicted impacts of increasing NO, emissions into this region of the atmosphere from, for example, the growth of global air traffic. C1 Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA. Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA. Nagoya Univ, Solar Terr Environm Lab, Aichi 442, Japan. NASA, Ames Res Ctr, Div Earth Sci, Moffett Field, CA 94035 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. RP Penn State Univ, Dept Meteorol, 503 Walker Bldg, University Pk, PA 16802 USA. EM faloona@essc.psu.edu; tan@essc.psu.edu; brune@essc.psu.edu RI Koike, Makoto/F-4366-2011; Kondo, Yutaka/D-1459-2012 NR 34 TC 52 Z9 53 U1 0 U2 12 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3771 EP 3783 DI 10.1029/1999JD900914 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000020 ER PT J AU Simpson, IJ Sive, BC Blake, DR Blake, NJ Chen, TY Lopez, JP Anderson, BE Sachse, GW Vay, SA Fuelberg, HE Kondo, Y Thompson, AM Rowland, FS AF Simpson, IJ Sive, BC Blake, DR Blake, NJ Chen, TY Lopez, JP Anderson, BE Sachse, GW Vay, SA Fuelberg, HE Kondo, Y Thompson, AM Rowland, FS TI Nonmethane hydrocarbon measurements in the North Atlantic Flight Corridor during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EMISSION INDEXES; TROPOSPHERIC OZONE; AIRCRAFT; SUCCESS AB Mixing ratios of nonmethane hydrocarbons (NMHCs) were not enhanced in whole air samples collected within the North Atlantic Flight Corridor (NAFC) during the fall of 1997. The investigation was conducted aboard NASA's DC-8 research aircraft, as part of the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX). NMHC enhancements were not detected within the general organized tracking system of the NAFC, nor during two tail chases of the DC-8's own exhaust. Because positive evidence of aircraft emissions was demonstrated by enhancements in both nitrogen oxides and condensation nuclei during SONEX, the NMHC results suggest that the commercial air traffic fleet operating in the North Atlantic region does not contribute at all or contributes negligibly to NMHCs in the NAFC. C1 Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Acad Sinica, Inst Earth Sci, Taipei 11529, Taiwan. Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. Nagoya Univ, Solar Terr Environm Lab, Aichi 442, Japan. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. EM isimpson@uci.edu RI Kondo, Yutaka/D-1459-2012; Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 24 TC 8 Z9 8 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3785 EP 3793 DI 10.1029/1999JD900750 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000021 ER PT J AU Singh, H Chen, Y Tabazadeh, A Fukui, Y Bey, I Yantosca, R Jacob, D Arnold, F Wohlfrom, K Atlas, E Flocke, F Blake, D Blake, N Heikes, B Snow, J Talbot, R Gregory, G Sachse, G Vay, S Kondo, Y AF Singh, H Chen, Y Tabazadeh, A Fukui, Y Bey, I Yantosca, R Jacob, D Arnold, F Wohlfrom, K Atlas, E Flocke, F Blake, D Blake, N Heikes, B Snow, J Talbot, R Gregory, G Sachse, G Vay, S Kondo, Y TI Distribution and fate of selected oxygenated organic species in the troposphere and lower stratosphere over the Atlantic SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GLOBAL SIMULATION; UNITED-STATES; MODEL; ATMOSPHERE; EMISSIONS; 2-METHYL-3-BUTEN-2-OL; HYDROCARBONS; AEROSOLS; HYDROGEN; NITROGEN AB A large number of oxygenated organic chemicals (peroxyacyl nitrates, alkyl nitrates, acetone, formaldehyde, methanol, methylhydroperoxide, acetic acid and formic acid) were measured during the 1997 Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) airborne field campaign over the Atlantic. In this paper, we present a first picture of the distribution of these oxygenated organic chemicals (Ox-organic) in the troposphere and the lower stratosphere, and assess their source and sink relationships. In both the troposphere and the lower stratosphere, the total atmospheric abundance of these oxygenated species (Sigma Ox-organic) nearly equals that of total nonmethane hydrocarbons (Sigma NMHC), which have been traditionally measured. A sizable fraction of the reactive nitrogen (10-30%) is present in its oxygenated organic form. The organic reactive nitrogen fraction is dominated by peroxyacetyl nitrate (PAN), with alkyl nitrates and peroxypropionyl nitrate (PPN) accounting for <5% of total NOy. Comparison of observations with the predictions of the Harvard three-dimensional global model suggests that in many key areas (e.g., formaldehyde and peroxides) substantial differences between measurements and theory are present and must be resolved. In the case of CH3OH, there appears to be a large mismatch between atmospheric concentrations and estimated sources, indicating the presence of major unknown removal processes. Instrument intercomparisons as well as disagreements between observations and model predictions are used to identify needed improvements in key areas. The atmospheric chemistry and sources of this group of chemicals is poorly understood even though their fate is intricately linked with upper tropospheric NOx and HOx cycles. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Harvard Univ, Cambridge, MA 02138 USA. Univ Calif Irvine, Irvine, CA 92697 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Rhode Isl, Ctr Atmospher Chem Studies, Narragansett, RI 02882 USA. Nagoya Univ, Aichi 4428507, Japan. Univ New Hampshire, Durham, NH 03824 USA. RP NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. EM hsingh@mail.arc.nasa.gov RI Kondo, Yutaka/D-1459-2012; Yantosca, Robert/F-7920-2014; Atlas, Elliot/J-8171-2015 OI Yantosca, Robert/0000-0003-3781-1870; NR 39 TC 192 Z9 195 U1 2 U2 23 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3795 EP 3805 DI 10.1029/1999JD900779 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000022 ER PT J AU Hannan, JR Fuelberg, HE Thompson, AM Bieberbach, G Knabb, RD Kondo, Y Anderson, BE Browell, EV Gregory, GL Sachse, GW Singh, HB AF Hannan, JR Fuelberg, HE Thompson, AM Bieberbach, G Knabb, RD Kondo, Y Anderson, BE Browell, EV Gregory, GL Sachse, GW Singh, HB TI Atmospheric chemical transport based on high-resolution model-derived winds: A case study SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TRACE-A; TRAJECTORIES; OZONE; AFRICA; AIR AB Flight 10 of NASA's Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) extended southwest of Lajes, Azores. A variety of chemical signatures was encountered. These signatures are examined in detail, relating them to meteorological data from a high-resolution numerical model having a horizontal grid spacing of 30 and 90 km with 26 vertical levels. The meteorological output at hourly intervals is used to create backward trajectories from the locations of the chemical signatures. Four major categories of chemical signatures are discussed: stratospheric, lightning, continental pollution, and a mixed chemical layer. The strong stratospheric signal is encountered just south of the Azores in a region of depressed tropopause height. Three chemical signatures at different altitudes in the upper troposphere are attributed to lightning. Backward trajectories from these signatures extend to locations of cloud-to-ground lightning, Specifically, results show that the trajectories pass over regions of lightning 1-2 days earlier over the eastern Gulf of Mexico and off the southeast coast of the United States. The lowest leg of the flight exhibits a chemical signature consistent with continental pollution. Trajectories from this signature are found to pass over the highly populated Northeast Corridor of the United States. Surface-based pollution apparently is lofted to the altitudes of the trajectories by convective clouds along the East Coast that did not contain lightning. Finally, a mixed layer is described. Its chemical signature is intermediate to those of lightning and continental pollution. Backward trajectories from this layer pass between the trajectories of the lightning and pollution signatures. Thus they likely are impacted by both sources. C1 Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Nagoya Univ, Solar Terr Lab, Toyokawa, Japan. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. EM fuelberg@met.fsu.edu RI Kondo, Yutaka/D-1459-2012; Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 26 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3807 EP 3820 DI 10.1029/1999JD900989 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000023 ER PT J AU Bieberbach, G Fuelberg, HE Thompson, AM Schmitt, A Hannan, JR Gregory, GL Kondo, Y Knabb, RD Sachse, GW Talbot, RW AF Bieberbach, G Fuelberg, HE Thompson, AM Schmitt, A Hannan, JR Gregory, GL Kondo, Y Knabb, RD Sachse, GW Talbot, RW TI Mesoscale numerical investigations of air traffic emissions over the North Atlantic during SONEX flight 8: A case study SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID 4-DIMENSIONAL DATA ASSIMILATION; PLANETARY BOUNDARY-LAYER; AIRCRAFT EMISSIONS; TROPOSPHERIC OZONE; SUPERSONIC AIRCRAFT; SOUTHERN AFRICA; JET AIRCRAFT; TRACE-A; MODEL; SENSITIVITY AB Chemical data from flight 8 of NASA's Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) exhibited signatures consistent with aircraft emissions, stratospheric air, and surface-based pollution. These signatures are examined in detail: focusing on the broad aircraft emission signatures that are several hundred kilometers in length. A mesoscale meteorological model provides high-resolution wind data that are used to calculate backward trajectories arriving at locations along the flight track. These trajectories are compared to aircraft locations in the North Atlantic Flight Corridor (NAFC) over a 27-33 hour period. Time series of flight level NO and the number of trajectory/aircraft encounters within the NAFC show excellent agreement. Trajectories arriving within the stratospheric and surface-based pollution regions are found to experience very few aircraft encounters. Conversely, there are many trajectory/aircraft encounters within the two chemical signatures corresponding to aircraft emissions. Even many detailed fluctuations of NO within the two aircraft signature regions correspond to similar fluctuations in aircraft encountered. These NO spikes are due to the superposition of 14 to 25 aircraft plumes transported to the DC-8 flight track during the previous 33 hours. Results confirm that aircraft emissions were responsible for two chemical signatures observed during SONEX flight 8. They also indicate that high-resolution meteorological modeling, when coupled with detailed aircraft location data, is useful for understanding chemical signatures from aircraft emissions at scales of several hundred kilometers. C1 Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Nagoya Univ, Solar Terr Environm Lab, Aichi 442, Japan. Deutsch Zentrum Luft & Raumfahrt, Abt Verkehrsforsch, D-51147 Cologne, Germany. Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. EM fuelberg@met.fsu.edu RI Kondo, Yutaka/D-1459-2012; Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 40 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3821 EP 3832 DI 10.1029/1999JD901036 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000024 ER PT J AU Meijer, EW van Velthoven, PFJ Thompson, AM Pfister, L Schlager, H Schulte, P Kelder, H AF Meijer, EW van Velthoven, PFJ Thompson, AM Pfister, L Schlager, H Schulte, P Kelder, H TI Model calculations of the impact of NOx from air traffic, lightning, and surface emissions, compared with measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AIRCRAFT EMISSIONS; OZONE; TRANSPORT; PARAMETERIZATION; DISTRIBUTIONS; TROPOSPHERE; NITROGEN; SCHEME AB The impact of NOx from aircraft emissions, lightning, and surface contributions on atmospheric nitrogen oxides and ozone in the North Atlantic flight corridor has been investigated with the three-dimensional global chemistry transport model TM3 by partitioning the nitrogen oxides and ozone according to source category. The results have been compared with Pollution from Aircraft Emissions in the North Atlantic flight corridor (POLINAT 2) and Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) airborne measurements in the North Atlantic flight corridor in 1997. Various cases have been investigated: measurements during a stagnant anticyclone and an almost cutoff low, both with expected high aircraft contributions, a southward bound flight with an expected strong flight corridor gradient and lightning contributions in the south, and a transatlantic flight with expected boundary layer pollution near the U.S. coast. The agreement between modeled results and measurements is reasonably good for NO and ozone. Also, the calculated impact of the three defined sources was consistent with the estimated exposure of the sampled air to these sources, obtained by specialized back trajectory model products. Model calculations indicate that aircraft contributes 55% to the mean NOx concentration and 10% to the O-3 concentration in the North Atlantic flight corridor in October 1997, whereas lightning and surface emissions add 15% and 25% to the NOx concentration and 20% and 30% to the O-3 concentration. C1 Royal Netherlands Meteorol Inst, KNMI, NL-3730 AE De Bilt, Netherlands. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. DLR, Deutsch Zentrum Luft & Raumfahrt, D-82234 Wessling, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Royal Netherlands Meteorol Inst, KNMI, POB 201, NL-3730 AE De Bilt, Netherlands. EM meijere@knmi.nl RI Meijer, E.W./K-7632-2013; Thompson, Anne /C-3649-2014 OI Meijer, E.W./0000-0003-4126-7492; Thompson, Anne /0000-0002-7829-0920 NR 32 TC 23 Z9 24 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3833 EP 3850 DI 10.1029/1999JD901052 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000025 ER PT J AU Allen, D Pickering, K Stenchikov, G Thompson, A Kondo, Y AF Allen, D Pickering, K Stenchikov, G Thompson, A Kondo, Y TI A three-dimensional total odd nitrogen (NOy) simulation during SONEX using a stretched-grid chemical transport model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GLOBAL LIGHTNING DISTRIBUTIONS; GENERAL-CIRCULATION MODEL; PARABOLIC METHOD PPM; 3-DIMENSIONAL SIMULATION; AIRCRAFT EMISSIONS; OZONE; CLIMATOLOGY; CHEMISTRY; IMPACT; PARAMETERIZATION AB The relative importance of various odd nitrogen (NOy) sources including lightning, aircraft, and surface emissions on upper tropospheric total odd nitrogen is illustrated as a first application of the three-dimensional Stretched-Grid University of Maryland/Goddard Chemical-Transport Model (SG-GCTM). The SG-GCTM has been developed to look at the effect of localized sources and/or small-scale mixing processes on the large-scale or global chemical balance. For this simulation the stretched grid was chosen so that its maximum resolution is located over eastern North America and the North Atlantic; a region that includes most of the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) flight paths, The SONEX period (October-November 1997) is simulated by driving the SG-GCTM with assimilated data from the Goddard Earth Observing System-Stratospheric Tracers of Atmospheric Transport Data Assimilation System (GEOS-STRAT DAS). A new algorithm is used to estimate the lightning flash rates needed to calculate NOy emission by lightning. This algorithm parameterizes the flash rate in terms of upper tropospheric convective mass flux. Model-calculated upper tropospheric NOy and NOy measurements from the NASA DC-8 aircraft are compared. Spatial variations in NOy were well captured especially with the stretched-grid run; however, model-calculated peaks due to "stratospheric" NOy are occasionally too large. The lightning algorithm reproduces the temporally and spatially averaged total flash rate accurately; however, the use of emissions from observed lightning flashes significantly improves the simulation on a few days, especially November 3, 1997, showing that significant uncertainty remains in parameterizing lightning in chemistry and transport models. Aircraft emissions contributed similar to 15% of the upper tropospheric NOy averaged along SONEX flight paths within the North Atlantic Flight Corridor with the contribution exceeding 40% during portions of some flights. C1 Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Nagoya Univ, Solar Terr Environm Lab, Aichi 442, Japan. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. EM allen@atmos.umd.edu RI Allen, Dale/F-7168-2010; Kondo, Yutaka/D-1459-2012; Pickering, Kenneth/E-6274-2012; Georgiy, Stenchikov/J-8569-2013; Thompson, Anne /C-3649-2014 OI Allen, Dale/0000-0003-3305-9669; Thompson, Anne /0000-0002-7829-0920 NR 65 TC 20 Z9 20 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3851 EP 3876 DI 10.1029/1999JD901029 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000026 ER PT J AU Jaegle, L Jacob, DJ Brune, WH Faloona, I Tan, D Heikes, BG Kondo, Y Sachse, GW Anderson, B Gregory, GL Singh, HB Pueschel, R Ferry, G Blake, DR Shetter, RE AF Jaegle, L Jacob, DJ Brune, WH Faloona, I Tan, D Heikes, BG Kondo, Y Sachse, GW Anderson, B Gregory, GL Singh, HB Pueschel, R Ferry, G Blake, DR Shetter, RE TI Photochemistry of HOx in the upper troposphere at northern midlatitudes SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HYDROGEN RADICALS; OZONE; OH; CHEMISTRY; NITROGEN; HYDROPEROXIDES; SURFACES; ATLANTIC; SUCCESS; DIOXIDE AB The factors controlling the concentrations of HOx radicals (= OH + peroxy) in the upper troposphere (8-12 km) are examined using concurrent aircraft observations of OH, HO2, H2O2, CH3OOH, and CH2O made during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) at northern midlatitudes in the fall, These observations, complemented by concurrent measurements of O-3 H2O, NO, peroxyacetyl nitrate (PAN), HNO3, CH4, CO, acetone, hydrocarbons, actinic fluxes, and aerosols, allow a highly constrained mass balance analysis of HOx and of the larger chemical family HOy (= HOx + 2 H2O2 + 2 CH3OOH + HNO2 + HNO4). Observations of OH and HO2 are successfully simulated to within 40% by a diel steady state model constrained with observed H2O2 and CH3OOH. The model captures 85% of the observed HOx variance: which is driven mainly by the concentrations of NOx (= NO + NO2) and by the strength of the HOx primary sources. Exceptions to the good agreement between modeled and observed HOx are at sunrise and sunset, where the model is too low by factors of 2-5, and inside cirrus clouds, where the model is too high by factors of 1.2-2, Heterogeneous conversion of NO? to HONO on aerosols (gamma(NO2) = 10(-3)) during the night followed by photolysis of HONO could explain part of the discrepancy at sunrise, Heterogeneous loss of HO2 on ice crystals (gamma(ice_HO2) = 0.025) could explain the discrepancy in cirrus. Primary sources of HOx from O(D-1) + H2O and acetone photolysis were of comparable magnitude during SONEX. The dominant sinks of HOy. were OH + HO2 (NOx < 50 parts per trillion by volume (pptv)) and OH + HNO4 (NOx > 50 pptv). Observed H2O2 concentrations are reproduced by model calculations to within 50% if one allows in the model for heterogeneous conversion of HO2 to H2O2 on aerosols (gamma(HO2) = 0.2) Observed CH3OOH concentrations are underestimated by a factor of 2 on average. Observed CH2O concentrations were usually below the 50 pptv detection limit, consistent with model results; however, frequent occurrences of high values in the observations (up to 350 pptv) are not captured by the model. These high values are correlated with high CH3OH and with cirrus clouds. Heterogeneous oxidation of CH3OH to CH2O on aerosols or ice crystals might provide an explanation (gamma(ice-CH3OH)similar to 0.01 would be needed). C1 Harvard Univ, Div Engn & Appl Sci, Cambridge, MA 02138 USA. Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Calif Irvine, Dept Chem, Irvine, CA 92717 USA. Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Rhode Isl, Grad Sch Oceanog, Narragansett, RI 02882 USA. Nagoya Univ, Solar Terr Environm Lab, Nagoya, Aichi, Japan. Natl Ctr Atmospher Res, Boulder, CO 80303 USA. RP Harvard Univ, Div Engn & Appl Sci, 29 Oxford St, Cambridge, MA 02138 USA. EM lyj@io.harvard.edu RI Kondo, Yutaka/D-1459-2012 NR 49 TC 120 Z9 120 U1 0 U2 18 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3877 EP 3892 DI 10.1029/1999JD901016 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000027 ER PT J AU Considine, DB Douglass, AR Connell, PS Kinnison, DE Rotman, DA AF Considine, DB Douglass, AR Connell, PS Kinnison, DE Rotman, DA TI A polar stratospheric cloud parameterization for the global modeling initiative three-dimensional model and its response to stratospheric aircraft SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TOTAL REACTIVE NITROGEN; ANTARCTIC STRATOSPHERE; SHUTTLE MISSIONS; SULFURIC-ACID; OZONE HOLE; HNO3; ICE; PHOTOCHEMISTRY; VALIDATION; DEPLETION AB We describe a new parameterization of polar stratospheric clouds (PSCs) which was written for and incorporated into the three-dimensional (3-D) chemistry and transport model (CTM) developed for NASA's Atmospheric Effects of Aviation Project (AEAP) by the Global Modeling Initiative (GMI). The parameterization was designed to respond to changes in NOy and H2O produced by high-speed civilian transport (HSCT) emissions. The parameterization predicts surface area densities (SADs) of both Type 1 and Type 2 PSCs for use in heterogeneous chemistry calculations. Type 1 PSCs are assumed to have a supercooled ternary sulfate (STS) composition, and Type 2 PSCs are treated as water ice with a coexisting nitric acid trihydrate (NAT) phase. Sedimentation is treated by assuming that the PSC particles obey lognormal size distributions, resulting in a realistic mass flux of condensed phase H2O and HNO3, We examine a simulation of the Southern Hemisphere high-latitude lower stratosphere winter and spring seasons driven by temperature and wind fields from a modified version of the National Center for Atmospheric Research (NCAR) Middle Atmosphere Community Climate Model Version 2 (MACCM2). Predicted PSC SADs and median radii for both Type 1 and Type 2 PSCs are consistent with observations, Gas phase HNO3 and H2O concentrations in the high-latitude lower stratosphere qualitatively agree with Cryogenic Limb Array Etalon Spectrometer (CLAES) HNO3 and Microwave Limb Sounder (MLS) H2O observations. The residual denitrification and dehydration of the model polar vortex after polar winter compares well with atmospheric trace molecule spectroscopy (ATMOS) observations taken during November 1994. When the NO, and H2O emissions of a standard 500-aircraft HSCT fleet with a NOx emission index of 5 are added, NOx and H2O concentrations in the Southern Hemisphere polar vortex before winter increase by up to 3%. This results in earlier onset of PSC formation, denitrification, and dehydration. Active Cry increases and produces small (similar to 1%) decreases in lower stratospheric vortex O-3 concentrations during the spring relative to the HSCT-free run. C1 Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. EM dbc@atmos.umd.edu RI Douglass, Anne/D-4655-2012 NR 53 TC 42 Z9 42 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 3955 EP 3973 DI 10.1029/1999JD900932 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000033 ER PT J AU Danilin, MY Santee, ML Rodriguez, JM Ko, MKW Mergenthaler, JM Kumer, JB Tabazadeh, A Livesey, NJ AF Danilin, MY Santee, ML Rodriguez, JM Ko, MKW Mergenthaler, JM Kumer, JB Tabazadeh, A Livesey, NJ TI Trajectory hunting: A case study of rapid chlorine activation in December 1992 as seen by UARS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; POLAR STRATOSPHERIC CLOUDS; 1995-96 ARCTIC WINTER; MLS OBSERVATIONS; OZONE; AEROSOL; VORTEX; HNO3; INSTRUMENT AB Trajectory hunting (i.e., a technique to find air parcels sampled at least twice over the course of a few days) is applied to analyze Upper Atmosphere Research Satellite (UARS) measurements in conjunction with the Atmospheric and Environmental Research, Inc. (AER) photochemical box model. As a case study, we investigate rapid chlorine activation in the Arctic lower stratosphere on December 29, 1992 associated with a polar stratospheric cloud (PSC) event. Eleven air parcels that have been sampled several times along 5-day trajectories at the 465 K (similar to 46 hPa), 520 K (similar to 31 hPa), and 585 K (similar to 22 hPa) levels were investigated. For the first time, the latest versions of the Cryogenic Limb Array Etalon Spectrometer (CLAES, version 9) and Microwave Limb Sounder (MLS, version 5) data sets are analyzed, and their consistency is assessed. A detailed sensitivity study with the AER photochemical box model along these trajectories leads to the conclusion that for the December 24-29, 1992 episode (1) the individual CLAES version 9 ClONO2 and MLS version 5 ClO measurements are self-consistent within their uncertainties; and (2) most of the time, UARS measurements of ClO, ClONO2, HNO3, and aerosol extinction at 780 cm(-1) agree within the range of their uncertainties with the model calculations. It appears that the HNO3 and aerosol extinction measurements for four parcels at 520 K look more supportive for the nitric acid trihydrate (NAT) scheme. However, the uncertainties in the individual UARS measurements and U.K. Meteorological Office temperature do not allow a definite discrimination between the NAT and supercooled ternary solution (STS) PSC schemes for this chlorine activation episode in December 1992. C1 Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. NASA, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Miami, Dept Marine & Atmospher Chem, Miami, FL 33149 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Atmospher & Environm Res Inc, 840 Mem Dr, Cambridge, MA 02139 USA. EM danilin@aer.com RI Rodriguez, Jose/G-3751-2013; Ko, Malcolm/D-5898-2015 OI Rodriguez, Jose/0000-0002-1902-4649; NR 44 TC 10 Z9 10 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2000 VL 105 IS D3 BP 4003 EP 4018 DI 10.1029/1999JD901054 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286ZP UT WOS:000085479000036 ER PT J AU Nikitin, A Champion, JP Tyuterev, VG Brown, LR Mellau, G Lock, M AF Nikitin, A Champion, JP Tyuterev, VG Brown, LR Mellau, G Lock, M TI The infrared spectrum of CH3D between 900 and 3200 cm(-1): extended assignment and modeling SO JOURNAL OF MOLECULAR STRUCTURE LA English DT Article DE infrared; methane; high resolution; polyad ID C3V MOLECULES; INTENSITIES; METHANE; SYSTEM; BAND; CH4 AB The high resolution infrared spectrum of CH3D in the region from 900 to 3200 cm(-1) has been analyzed on the basis of Fourier transform spectra recorded at Kitt Peak and at Giessen, A theoretical model for an effective hamiltonian in terms of irreducible tensor operators recently adapted to symmetric top molecules has been used in order to consider simultaneously all available transitions between the lowest three polyads of the molecule: the Ground State (G.S.), the Triad (three interacting fundamental bands in the 8 mu m region) and the Nonad (nine interacting bands in the 4 mu m region). A preliminary simultaneous fit of 3467 Triad-G.S., 5208 Nonad-G.S., and 2487 Nonad-Triad (bot band) transition wavenumbers has been done. The standard deviations achieved were 2.1, 4.7 and 4.3 x 10(-3) cm(-1), respectively. A preliminary analysis of the transition intensities was also undertaken at a level of precision of the order of 5% or better. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Bourgogne, Phys Lab, CNRS, Unit Associee, F-21078 Dijon, France. Russian Acad Sci, Inst Atmospher Opt, Lab Theoret Spect, Tomsk 634055, Russia. Univ Reims, Fac Sci, UPRESA CNRS 1434, Lab Spect Mol Atmospher, F-51623 Reims, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. JLU, Inst Chem Phys, D-35392 Giessen, Germany. RP Champion, JP (reprint author), Univ Bourgogne, Phys Lab, CNRS, Unit Associee, 9 Ave A Savary,BP 47870, F-21078 Dijon, France. RI Champion, Jean-Paul/C-3963-2009; Nikitin, Andrei/K-2624-2013; Mellau, Georg Christopher/A-8886-2017 OI Nikitin, Andrei/0000-0002-4280-4096; Mellau, Georg Christopher/0000-0001-8209-5733 NR 27 TC 36 Z9 36 U1 0 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-2860 J9 J MOL STRUCT JI J. Mol. Struct. PD FEB 16 PY 2000 VL 517 BP 1 EP 24 DI 10.1016/S0022-2860(99)00235-5 PG 24 WC Chemistry, Physical SC Chemistry GA 286RF UT WOS:000085458400002 ER PT J AU Devi, VM Benner, DC Smith, MAH Rinsland, CP Brown, LR AF Devi, VM Benner, DC Smith, MAH Rinsland, CP Brown, LR TI Measurements of air broadening, pressure shifting and off diagonal relaxation matrix coefficients in the nu(3) band of (CH3D)-C-12 SO JOURNAL OF MOLECULAR STRUCTURE LA English DT Article DE methane; monodeuterated methane; infrared spectra; Fourier transform infrared spectroscopy; spectral lineshape ID DIODE-LASER MEASUREMENTS; INFRARED OBSERVATIONS; LORENTZ HALFWIDTHS; LINE-INTENSITIES; SPECTRAL REGION; NU-2 BAND; CH3D; TEMPERATURES; (CH4)-C-12; DATABASE AB A multispectrum nonlinear least-squares fitting technique has been applied to determine Lorentz air-broadening coefficients and air induced pressure-shift coefficients of (CH3D)-C-12 for the nu(3) fundamental band in the spectral region between 1154 and 1430 cm(-1). This analysis has utilized 11 absorption spectra recorded at an unapodized resolution of 0.005 cm(-1) with the McMath-Pierce Fourier transform spectrometer of the National Solar Observatory (NSO) on Kitt Peak. Low pressure spectra (with 1-2.99 Torr of enriched (CH3D)-C-12 samples) as well as lean mixtures (approximate to 1%) of (CH3D)-C-12 in dry air (total pressures of 100-400 Torr) at room temperature have been measured to determine the pressure broadening coefficients of more than 360 vs transitions with quantum numbers as high as J " = 17 and K " = 17. The measured air-broadening coefficients range from 0.0155 to 0.0726 cm(-1) atm(-1) at 296 K. The pressure-induced shift coefficients vary from about - 0.0086 to + 0.0058 cm(-1) atm(-1) The majority of the shifts are negative, and the positive shifts often involve transitions with J " = K ". Weak line mixing effects have also been observed in a few high J lines with K " = 3 and approximate off diagonal relaxation matrix coefficients were determined for several A(+)A(-) (A1A2) split components. At low to medium values of J, the A(+)A(-) splitting is extremely small, and the two components are practically unresolved. Variations of the measured parameters with the A- and E- symmetry species and the rotational quantum numbers of the transitions involved are discussed. The present results are compared to the few available experimental values in the literature. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Coll William & Mary, Dept Phys, Williamsburg, VA 23187 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Devi, VM (reprint author), Coll William & Mary, Dept Phys, Box 8795, Williamsburg, VA 23187 USA. NR 37 TC 21 Z9 21 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-2860 J9 J MOL STRUCT JI J. Mol. Struct. PD FEB 16 PY 2000 VL 517 BP 455 EP 475 DI 10.1016/S0022-2860(99)00269-0 PG 21 WC Chemistry, Physical SC Chemistry GA 286RF UT WOS:000085458400039 ER PT J AU Lewis, RM Patera, AT Peraire, J AF Lewis, RM Patera, AT Peraire, J TI A posteriori finite element bounds for sensitivity derivatives of partial-differential-equation outputs SO FINITE ELEMENTS IN ANALYSIS AND DESIGN LA English DT Article DE A posteriori finite element bounds; sensitivity calculations; sensitivity equations ID GRADIENT INFORMATION; ALGORITHMS AB We present a Neumann-subproblem a posteriori finite element procedure for the efficient and accurate calculation of rigorous, "constant-free" upper and lower bounds for sensitivity derivatives of functionals of the solutions of partial differential equations. The design motivation for sensitivity derivative error control is discussed; the a posteriori finite element procedure is described; the asymptotic bounding properties and computational complexity of the method are summarized; and illustrative numerical results are presented. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. MIT, Dept Mech Engn, Cambridge, MA 02139 USA. MIT, Dept Aeronaut & Astronaut, Cambridge, MA 02139 USA. RP Lewis, RM (reprint author), NASA, Langley Res Ctr, ICASE, Mail Stop 132C, Hampton, VA 23681 USA. NR 29 TC 2 Z9 2 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-874X J9 FINITE ELEM ANAL DES JI Finite Elem. Anal. Des. PD FEB 15 PY 2000 VL 34 IS 3-4 BP 271 EP 290 PG 20 WC Mathematics, Applied; Mechanics SC Mathematics; Mechanics GA 285ZU UT WOS:000085418900003 ER PT J AU Earle, GD Kane, TJ Pfaff, RF Bounds, SR AF Earle, GD Kane, TJ Pfaff, RF Bounds, SR TI Ion layer separation and equilibrium zonal winds in midlatitude sporadic E SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INTERMEDIATE AB In-situ observations of a moderately strong midlatitude sporadic-E layer show a separation in altitude between distinct sublayers composed of Fe+, Mg+, and NO+. From these observations it is possible to estimate the zonal wind field consistent with diffusive equilibrium near the altitude of the layer. The amplitude of the zonal wind necessary to sustain the layer against diffusive effects is less than 10 mis, and the vertical wavelength is less than 10 km. C1 Univ Texas, WB Hanson Ctr Space Sci, Richardson, TX 75083 USA. Penn State Univ, State Coll, University Pk, PA 16802 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Earle, GD (reprint author), Univ Texas, WB Hanson Ctr Space Sci, 2601 N Floyd Rd, Richardson, TX 75083 USA. RI Pfaff, Robert/F-5703-2012 OI Pfaff, Robert/0000-0002-4881-9715 NR 12 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 2000 VL 27 IS 4 BP 461 EP 464 DI 10.1029/1999GL900572 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 284QN UT WOS:000085343600005 ER PT J AU Huddleston, MM Pollock, CJ Wuest, MP Pickett, JS Moore, TE Peterson, WK AF Huddleston, MM Pollock, CJ Wuest, MP Pickett, JS Moore, TE Peterson, WK TI Toroidal ion distributions observed at high altitudes equatorward of the cusp SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ENERGIZATION; ACCELERATION; INSTRUMENT; REGION; MODEL AB We examine events where the TIDE and TIMAS ion instruments on board the Polar spacecraft have observed transversely accelerated ions (TAI) at altitudes greater than 20,000 km. We report both H+ and O+ populations that have been heated perpendicular to the local B field but that also have a sharp low-energy cutoff to the distribution occurring at 20 - 100 eV. Analysis of an event on 21 April 1996 indicates that the formation of ion toroids may be related to solitary structures or low frequency wave pulses observed during the event. We address some of the implications of using time (as opposed to frequency) domain techniques to analyze wave/particle energization events. C1 SW Res Inst, San Antonio, TX USA. Univ Iowa, Iowa City, IA USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Lockheed Palo Alto Res Labs, Palo Alto, CA 94304 USA. RP Huddleston, MM (reprint author), Vanderbilt Univ, Dept Phys & Astron, 221 Kirkland Hall, Nashville, TN 37235 USA. RI Moore, Thomas/D-4675-2012; Peterson, WK/A-8706-2009 OI Moore, Thomas/0000-0002-3150-1137; Peterson, WK/0000-0002-1513-6096 NR 13 TC 17 Z9 17 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 2000 VL 27 IS 4 BP 469 EP 472 DI 10.1029/1999GL010712 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 284QN UT WOS:000085343600007 ER PT J AU Gaidos, EJ Gudel, M Blake, GA AF Gaidos, EJ Gudel, M Blake, GA TI The faint young Sun paradox: An observational test of an alternative solar model SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERIC CARBON-DIOXIDE; MASS-LOSS; MICROWAVE EMISSION; MAIN-SEQUENCE; DWARF STARS; EARLY EARTH; LITHIUM; MARS; LIMITS; TEMPERATURES AB We report the results of deep observations at radio (3.6 cm) wavelengths of the nearby solar-type star pi(01) Ursa Majoris with the Very Large Array (VLA) intended to test an alternative theory of solar luminosity evolution. The standard model predicts a solar luminosity only 75% of the present value and surface temperatures below freezing on Earth and Mars at 4 Ga, seemingly in conflict with geologic evidence for liquid water on these planets. An alternative model invokes a compensatory mass loss through a declining solar wind that results in a more consistent early luminosity.: The free-free emission from an enhanced wind around nearby young Sun-like stars should be detectable at microwave frequencies. Our observations of pi(01) UMa, a 300 million year-old solar-mass star, place an upper limit on the mass loss rate of 4 - 5 x 10(-11) M.yr(-1). Total mass loss from such a star over 4 Gyr would be less than 6%. If this star is indeed an analog of the early Sun, it casts doubt on the alternative model as a solution to the faint young Sun paradox, particularly for Mars. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Paul Scherrer Inst, CH-5232 Villigen, Switzerland. RP Gaidos, EJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. RI Guedel, Manuel/C-8486-2015 OI Guedel, Manuel/0000-0001-9818-0588 NR 36 TC 34 Z9 34 U1 2 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 2000 VL 27 IS 4 BP 501 EP 503 DI 10.1029/1999GL010740 PG 3 WC Geosciences, Multidisciplinary SC Geology GA 284QN UT WOS:000085343600015 PM 11543273 ER PT J AU McCormack, JP Fu, R Read, WG AF McCormack, JP Fu, R Read, WG TI The influence of convective outflow on water vapor mixing ratios in the tropical upper troposphere: An analysis based on UARS MLS measurements SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SURFACE-TEMPERATURE; DEEP CONVECTION; MOISTURE AB The source of increased water vapor mixing ratios over the central and eastern tropical Pacific region during the 1992 El Nino event is examined using measurements of upper tropospheric water vapor provided by the Microwave Limb Sounder (MLS) on board the Upper Atmosphere Research Satellite. Horizontal winds on isentropic surfaces are combined with ISCCP cloud information to provide back-trajectory calculations free of high clouds. These calculations show that the water vapor mixing ratio of an air parcel in the cloud-free regions of the eastern Pacific decreases to approximately one-half of its original value within the first 30 hours after encountering deep convection. This analysis also finds a larger number of air parcels encountering deep convection within 30 hours of observation, and therefore having higher mixing ratios, in March-April 1992 compared to March-April 1994. Hence, increased deep convection over the equatorial central and eastern Pacific in 1992 contributed to the moistening of the downstream tropical upper troposphere. C1 Univ Arizona, Inst Atmospher Phys, Tucson, AZ 85721 USA. CALTECH, Jet Propuls Lab, Pasadena, CA 91125 USA. RP McCormack, JP (reprint author), Univ Arizona, Inst Atmospher Phys, POB 210081, Tucson, AZ 85721 USA. RI Fu, Rong/B-4922-2011; OI McCormack, John/0000-0002-3674-0508 NR 17 TC 11 Z9 11 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 2000 VL 27 IS 4 BP 525 EP 528 DI 10.1029/1999GL010477 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 284QN UT WOS:000085343600021 ER PT J AU Goodman, SJ Buechler, DE Knupp, K Driscoll, K McCaul, EW AF Goodman, SJ Buechler, DE Knupp, K Driscoll, K McCaul, EW TI The 1997-98 El Nino event and related wintertime lightning variations in the southeastern United States SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The Fl Nine Southern Oscillation (ENSO) is a climate anomaly responsible for worldwide weather impacts ranging from droughts to floods. In the United States, warm episode years are known to produce above normal rainfall along the Southeast U.S. Gulf Coast and into the Gulf of Mexico, with the greatest response observed in the October-March period of the warm episode year. The 1997-98 warm episode is notable for being the strongest event since 1982-83. With the recent launch of a lightning sensor on NASA's Tropical Rainfall Measuring Mission (TRMM) in November 1997 and the detailed coverage of the U.S. National Lightning Detection Network (NLDN), such interannual changes in lightning activity can be examined with far greater detail than ever before. For the 1997-98 ENSO event the most significant year-to-year changes in lightning frequency worldwide occurred along the Gulf Coast acid within the Gulf of Mexico basin during the Northern Hemisphere winter. Within a broad swath across the northern Gulf of Mexico basin there is a 100-150% increase in lightning days year-to-year (a peak of 33 days in the winter of 1997-98 vs. only 15 days or fewer in both the 1996-97 and 1998-99 winter). In addition, there is a nearly 200% increase in lightning hours (a peak of 138 hours in 1996-97 vs. 50 hours in both 1996-97 and 1998-99). The increase in lightning activity during ENSO occurs in association with a 100% increase in the number of synoptic scale cyclones that developed within or moved through the Gulf basin. The primary variables controlling these enhancements in thunderstorm activity are the position:and strength of the jet stream. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35899 USA. RP Goodman, SJ (reprint author), Global Hydrol & Climate Ctr, 977 Explorer Blvd, Huntsville, AL 35806 USA. NR 11 TC 40 Z9 44 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 2000 VL 27 IS 4 BP 541 EP 544 DI 10.1029/1999GL010808 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 284QN UT WOS:000085343600025 ER PT J AU Sato, OT Polito, PS Liu, WT AF Sato, OT Polito, PS Liu, WT TI Importance of salinity measurements in the heat storage estimation from TOPEX/POSEIDON SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OCEAN; VARIABILITY; ALTIMETRY; TOPEX AB Sea surface height anomalies from satellite altimeter data are used to estimate heat storage. Since variability in sea surface height is mostly due to expansion and contraction of the water column it can be correlated with variations in the heat and salt content. Therefore, estimation of heat storage from altimeter data, when compared to in situ estimates, requires corrections for the haline effect. Three sites with a nearly continuous time series of temperature and salinity profiles simultaneous with TOPEX/POSEIDON data are studied: HOT, CalCOFI and Hydrostation "S". Haline corrections based on in situ and climatological salinity measurements are contrasted. For the studied regions, the haline corrections based on climatology provide equivalent or worse results than not applying a correction at all. The use of in situ salinity estimates decreased the differences between the heat storage estimates (up to 17 x 10(7) J m(-2)) and significantly improved their correlation (up to 0.18). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sato, OT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. RI Polito, Paulo/F-3040-2013; Sato, Olga/G-3656-2013 OI Polito, Paulo/0000-0003-2217-3853; Sato, Olga/0000-0003-0751-4373 NR 11 TC 20 Z9 20 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 2000 VL 27 IS 4 BP 549 EP 551 DI 10.1029/1999GL011003 PG 3 WC Geosciences, Multidisciplinary SC Geology GA 284QN UT WOS:000085343600027 ER PT J AU Otterman, J Ardizzone, J Atlas, R Hu, H Jusem, JC Starr, D AF Otterman, J Ardizzone, J Atlas, R Hu, H Jusem, JC Starr, D TI Winter-to-spring transition in Europe 48-54 degrees N: From temperature control by advection to control by insolation SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NORTHERN AB As established in previous studies, and analyzed further herein for the years 1988-1998, warm advection from the North Atlantic is the predominant control of the surface-air temperature in northern-latitude Europe in late winter. This thesis is supported by the substantial correlation Cti between the speed of the southwesterly surface winds over the eastern North Atlantic, as quantified by a specific Index Ina, and the 2-meter level temperature Ts over central Europe (48-54 degrees N; 5-25 degrees E), for January, February and early March, In mid-March and subsequently,,the correlation Cti drops drastically (quite often it is negative). The change in the relationship between Ts and Ina marks a transition in the control of the surface-air temperature. As (a) the sun rises higher in the sky, (b) the snows melt (the surface absorptivity can increase by a factor of 3.0), (c) the ocean-surface winds weaken, and (d) the temperature difference between land and ocean (which we analyze) becomes small, absorption of insolation replaces the warm advection as the dominant control of the continental temperature. We define the onset of spring by this transition, which evaluated for the period of our study occurs at pentad 16 (Julian Dare 76, that is, March 16). The control by insolation means that the surface is cooler under cloudy conditions than under clear skies. This control produces a much smaller interannual variability of the surface temperature and of the lapse rate than prevailing in winter, when the control is by advection. Regional climatic data would be of greatest value for agriculture and forestry if compiled for well-defined seasons. For continental northern latitudes, analysis presented here of factors controlling the surface temperature appears an appropriate tool for this task. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Gen Sci Corp, Beltsville, MD USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Harvard Univ, Cambridge, MA 02138 USA. RP Otterman, J (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 9103, Greenbelt, MD 20771 USA. RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 17 TC 2 Z9 2 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 2000 VL 27 IS 4 BP 561 EP 564 DI 10.1029/1999GL006090 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 284QN UT WOS:000085343600030 ER PT J AU Zhu, Y Newell, RE Read, WG AF Zhu, Y Newell, RE Read, WG TI Factors controlling upper-troposphere water vapor SO JOURNAL OF CLIMATE LA English DT Article ID ATMOSPHERIC RIVERS; TROPICAL PACIFIC; UARS MLS; CIRCULATION; MOISTURE; STRATOSPHERE; CONVECTION; TRANSPORT; COOLNESS; HUMIDITY AB The seasonal changes of the upper-tropospheric humidity are studied with the water vapor data from the Microwave Limb Sounder on the National Aeronautics and Space Administration's Upper Atmosphere Research Satellite, and the winds and vertical velocity data obtained from the European Centre for Medium-Range Weather Forecasts. Using the same algorithm for vertical transport as that used for horizontal transport (by Zhu and Newell), the authors End that the moisture in the tropical upper troposphere may be increased mainly by intensified local convection in a small portion, less than 10%, of the whole area between 40 degrees S and 40 degrees N. The contribution of large-scale background circulations and divergence of horizontal transport is relatively small in these regions. These dynamic processes cannot be revealed by the traditional analyses of moisture fluxes. The negative response suggested by Lindzen, with enhanced convection in the Tropics being accompanied by subsidence drying in the subtropics, also exists, but the latter does not apparently dominate in the moisture budget. C1 MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Zhu, Y (reprint author), MIT, Dept Earth Atmospher & Planetary Sci, 54-1822,77 Massachusetts Ave, Cambridge, MA 02139 USA. NR 24 TC 7 Z9 8 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD FEB 15 PY 2000 VL 13 IS 4 BP 836 EP 848 DI 10.1175/1520-0442(2000)013<0836:FCUTWV>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 301HA UT WOS:000086303700010 ER PT J AU Murtugudde, R McCreary, JP Busalacchi, AJ AF Murtugudde, R McCreary, JP Busalacchi, AJ TI Oceanic processes associated with anomalous events in the Indian Ocean with relevance to 1997-1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID INDONESIAN THROUGHFLOW; TROPICAL OCEANS; MIXED-LAYER; MODEL AB An anomalous climatic event occurred in the Indian Ocean (IO) region during 1997-1998, which coincided with a severe drought in Indonesia and floods in parts of eastern Africa. Cool sea surface temperature anomalies (SSTAs) were present in the eastern IO along and south of the equator. Beginning in July 1997, warm SSTAs appeared in the western IO, and they peaked in February 1998. An ocean general circulation model is employed to investigate the dynamic and thermodynamic processes that caused the SSTAs associated with this and other similar IO events. The eastern cooling resulted from unusually strong upwelling along the equator and Sumatra. The Sumatran upwelling was forced both locally by the stronger alongshore winds and remotely by equatorial and coastal Kelvin waves. By the end of 1997, weakening of the winds and the associated reduction in latent heat loss led to the elimination of the cold SST anomalies in the east. The western warming was initiated by weaker Southwest Monsoon winds and maintained by enhanced precipitation forcing, which resulted in a barrier layer structure. Analysis of the mixed layer temperature equation indicates that a downwelling Rossby wave contribution was crucial for sustaining the warming into February 1998. It is tempting to suppose that the 1997 event was related to the El Nino-Southern Oscillation (ENSO) event that took place in the Pacific at the same time. Indeed, weaker IO events occur quite regularly in the control run that evolve similarly to the 1997 event, and they are often but not always related to ENSO. We speculate that these events represent a natural mode of oscillation in the IO, which is externally forced by ENSO but also excited by ocean-atmosphere interactions internal to the IO. C1 Univ Maryland, ESSIC, College Pk, MD 20742 USA. Univ Hawaii, Int Pacific Res Ctr, Honolulu, HI 96822 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD USA. RP Murtugudde, R (reprint author), Univ Maryland, ESSIC, College Pk, MD 20742 USA. NR 19 TC 320 Z9 336 U1 3 U2 24 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD FEB 15 PY 2000 VL 105 IS C2 BP 3295 EP 3306 DI 10.1029/1999JC900294 PG 12 WC Oceanography SC Oceanography GA 284ML UT WOS:000085336100005 ER PT J AU Geiger, CA Zhao, YH Liu, AK Hakkinen, S AF Geiger, CA Zhao, YH Liu, AK Hakkinen, S TI Large-scale comparison between buoy and SSM/I drift and deformation in the Eurasian Basin during winter 1992-1993 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA-ICE DRIFT; TRACKING; MOTION; SAR AB A method for comparing sea ice velocity, divergence, and shear at the large-scale between buoys and Special Sensor Micro wave Imager (SSM/I) is presented. For initial testing, the method is applied in the Eurasian Basin because of its relatively simple circulation dominated by the wind. Using eight Argos buoys, 11 strain rate arrays 100-600 km in size are constructed. Daily 100 km resolution sea ice motion derived from SSM/I 85 GHz brightness temperatures is sampled 100-1000 km from the center of the buoy arrays. Over this range of possible scales, a minimum RMS difference (RMSD) for deformation is used to identify an optimal inclusion radius of 600 km corresponding to a length scale of 1000 km. This length scale is typical of local storms confirming a strong connection between wind and observed sea ice motion. On the basis of all II arrays, an average RMSD of 2.48 +/- 0.05 cm s(-1) for velocity vector and 8.8 +/- 0.9 x 10(-8) s(-1) using all four deformation components (partial derivative u(i)/partial derivative x(j)) is found at the optimal inclusion radius corresponding to average correlation coefficients of 0.896 +/- 0.002 and 0.729 +/- 0.030, respectively. RMSD are found to scale with the temporal and spatial uncertainties of the SSM/I suggesting that even better results can be achieved with higher resolution instruments. C1 NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Greenbelt, MD 20771 USA. Caelum Res Corp, Rockville, MD 20850 USA. RP Geiger, CA (reprint author), Univ Delaware, Ctr Climat Res, Dept Geog, 216 Pearson Hall, Newark, DE 19716 USA. RI Hakkinen, Sirpa/E-1461-2012 NR 20 TC 8 Z9 8 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD FEB 15 PY 2000 VL 105 IS C2 BP 3357 EP 3368 DI 10.1029/1999JC900285 PG 12 WC Oceanography SC Oceanography GA 284ML UT WOS:000085336100009 ER PT J AU Anantram, MP Govindan, TR AF Anantram, MP Govindan, TR TI Transmission through carbon nanotubes with polyhedral caps SO PHYSICAL REVIEW B LA English DT Article ID STATES; PROBES AB We study electron transport between capped carbon nanotubes and a substrate, and relate the transmission probability to the local density of states in the cap. Our results show that the transmission probability mimics the behavior of the density of states at all energies except: those that correspond to localized states in the cap. Close proximity of a substrate causes hybridization of the localized state. As a result, transmission paths open from the substrate to nanotube continuum states via the localized states in the cap. Interference between various transmission paths gives rise to antiresonances in the transmission probability, with the minimum transmission equal to zero at energies of the localized states. Defects in the nanotube that are placed close to the cap cause resonances in the transmission probability, instead of antiresonances, near the localized energy levels. Depending on the spatial position of defects, these resonant states are capable of carrying a large current. These results are relevant to carbon nanotube based studies of molecular electronics and probe tip applications. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Anantram, MP (reprint author), NASA, Ames Res Ctr, Mail Stop T27A-1, Moffett Field, CA 94035 USA. EM anant@nas.nasa.gov NR 19 TC 14 Z9 14 U1 0 U2 2 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD FEB 15 PY 2000 VL 61 IS 7 BP 5020 EP 5025 DI 10.1103/PhysRevB.61.5020 PG 6 WC Physics, Condensed Matter SC Physics GA 287GB UT WOS:000085497200114 ER PT J AU Peteet, D AF Peteet, D TI Sensitivity and rapidity of vegetational response to abrupt climate change SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID GLACIAL ENVIRONMENTAL-CHANGE; SOUTHEASTERN NEW-YORK; YOUNGER-DRYAS; REGIONAL SYNTHESIS; LAST DEGLACIATION; HUDSON HIGHLANDS; NORTHEASTERN USA; NORTH-ATLANTIC; GREENLAND; RECORDS AB Rapid climate change characterizes numerous terrestrial sediment records during and since the last glaciation. Vegetational response is best expressed in terrestrial records near ecotones. where sensitivity to climate change is greatest, and response times are as short: as decades. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Lamont Doherty Earth Observ, New Core Lab, Palisades, NY 10964 USA. RP Peteet, D (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 33 TC 56 Z9 58 U1 0 U2 10 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD FEB 15 PY 2000 VL 97 IS 4 BP 1359 EP 1361 DI 10.1073/pnas.97.4.1359 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 285VU UT WOS:000085409600013 PM 10677467 ER PT J AU Weiss, BP Yung, YL Nealson, KH AF Weiss, BP Yung, YL Nealson, KH TI Atmospheric energy for subsurface life on Mars? SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID MARTIAN ATMOSPHERE; ICE; SPECTROSCOPY; DEUTERIUM; STABILITY; LIMITS; SEARCH; MODEL; EARTH; H2O2 AB The location and density of biologically useful energy sources on Mars will limit the biomass, spatial distribution, and organism size of any biota. Subsurface Martian organisms could be supplied with a large energy flux from the oxidation of photochemically produced atmospheric H-2 and CO diffusing into the regolith, However, surface abundance measurements of these gases demonstrate that no more than a few percent of this available flux is actually being consumed, suggesting that biological activity driven by atmospheric H-2 and CO is limited in the top few hundred meters of the subsurface. This is significant because the available but unused energy is extremely large: for organisms at 30-m depth, it is 2,000 timer previous estimates of hydrothermal and chemical weathering energy and far exceeds the energy derivable from other atmospheric gases. This also implies that the apparent scarcity of life on Mars is not attributable to lack of energy. Instead, the availability of liquid water may be a more important factor limiting biological activity because the photochemical energy flux can only penetrate to 100- to 1,000-m depth, where most H2O is probably frozen. Because both atmospheric and Viking lander soil data provide little evidence for biological activity, the detection of short-lived trace gases will probably be a better indicator of any extant Martian life. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Weiss, BP (reprint author), CALTECH, Div Geol & Planetary Sci, MS 150-21, Pasadena, CA 91125 USA. NR 33 TC 52 Z9 53 U1 2 U2 7 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD FEB 15 PY 2000 VL 97 IS 4 BP 1395 EP 1399 DI 10.1073/pnas.030538097 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 285VU UT WOS:000085409600021 PM 10660689 ER PT J AU Kirschvink, JL Gaidos, EJ Bertani, LE Beukes, NJ Gutzmer, J Maepa, LN Steinberger, RE AF Kirschvink, JL Gaidos, EJ Bertani, LE Beukes, NJ Gutzmer, J Maepa, LN Steinberger, RE TI Paleoproterozoic snowball Earth: Extreme climatic and geochemical global change and its biological consequences SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID SUPEROXIDE-DISMUTASE; MANGANESE DEPOSITS; SOUTH-AUSTRALIA; LOW PALEOLATITUDE; IRON-FORMATION; GLACIATION; ATMOSPHERE; EVOLUTION; AFRICA; ORIGIN AB Geological, geophysical, and geochemical data support a theory that Earth experienced several intervals of intense, global glaciation ("snowball Earth" conditions) during Precambrian time. This snowball model predicts that postglacial, greenhouse-induced warming would lead to the deposition of banded iron formations and cap carbonates. Although global glaciation would have drastically curtailed biological productivity, melting of the oceanic ice would also have induced a cyanobacterial bloom, leading to an oxygen spike in the euphotic zone and to the oxidative precipitation of iron and manganese. A Paleoproterozoic snowball Earth at 2.4 Giga-annum before present (Ga) immediately precedes the Kalahari Manganese Field in southern Africa, suggesting that this rapid and massive change in global climate was responsible for its deposition. As large quantities of Oz are needed to precipitate this Mn, photosystem II and oxygen radical protection mechanisms must have evolved before 2.4 Ga. This geochemical event may have triggered a compensatory evolutionary branching in the Fe/Mn superoxide dismutase enzyme, providing a Paleoproterozoic calibration point for studies of molecular evolution. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. CALTECH, Div Biol, Pasadena, CA 91125 USA. Rand Afrikaans Univ, Dept Geol, ZA-2006 Johannesburg, South Africa. RP Kirschvink, JL (reprint author), CALTECH, Div Geol & Planetary Sci, 170-25, Pasadena, CA 91125 USA. NR 67 TC 202 Z9 221 U1 6 U2 100 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD FEB 15 PY 2000 VL 97 IS 4 BP 1400 EP 1405 DI 10.1073/pnas.97.4.1400 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 285VU UT WOS:000085409600022 PM 10677473 ER PT J AU Lobitz, B Beck, L Huq, A Wood, B Fuchs, G Faruque, ASG Colwell, R AF Lobitz, B Beck, L Huq, A Wood, B Fuchs, G Faruque, ASG Colwell, R TI Climate and infectious disease: Use of remote sensing for detection of Vibrio cholerae by indirect measurement SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID GLOBAL CLIMATE; TEMPERATURE; SALINITY; GROWTH AB It has long been known that cholera outbreaks can be initiated when Vibrio cholerae, the bacterium that causes cholera, is present in drinking water in sufficient numbers to constitute an infective dose, if ingested by humans. Outbreaks associated with drinking or bathing in unpurified river or brackish water may directly or indirectly depend on such conditions as water temperature, nutrient concentration, and plankton production that may be favorable for growth and reproduction of the bacterium. Although these environmental parameters have routinely been measured by using water samples collected aboard research ships, the available data sets are sparse and infrequent. Furthermore, shipboard data acquisition is both expensive and time-consuming. Interpolation to regional scales can also be problematic. Although the bacterium, V. cholerae, cannot be sensed directly, remotely sensed data can be used to infer its presence. In the study reported here, satellite data were used to monitor the timing and spread of cholera. Public domain remote sensing data for the Bay of Bengal were compared directly with cholera case data collected in Bangladesh from 1992-1995, The remote sensing data included sea surface temperature and sea surface height. It was discovered that sea surface temperature shows an annual cycle similar to the cholera case data. Sea surface height may be an indicator of incursion of plankton-laden water inland, e.g., tidal rivers, because it was also found to be correlated with cholera outbreaks. The extensive studies accomplished during the past 25 years, confirming the hypothesis that V, cholerae is autochthonous to the aquatic environment and is a commensal of zooplankton, i.e,, copepods, when combined with the findings of the satellite data analyses, provide strong evidence that cholera epidemics are climate-linked. C1 Univ Maryland, Dept Cell & Mol Biol, College Pk, MD 20742 USA. NASA, Johnson Controls World Serv, Ctr Hlth Applicat Aerosp Related Technol, Ames Res Ctr, Moffett Field, CA 94035 USA. Calif State Univ, Dept Earth Syst Sci & Policy, Monterey Bay, CA 93955 USA. Univ Maryland, Ctr Marine Biotechnol, Inst Biotechnol, Baltimore, MD 21202 USA. Int Ctr Diarrhoeal Dis Res, Dhaka 1000, Bangladesh. RP Colwell, R (reprint author), Univ Maryland, Dept Cell & Mol Biol, College Pk, MD 20742 USA. FU NIAID NIH HHS [1RO1AI39129-01]; PHS HHS [R824995-01] NR 13 TC 239 Z9 248 U1 9 U2 39 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD FEB 15 PY 2000 VL 97 IS 4 BP 1438 EP 1443 DI 10.1073/pnas.97.4.1438 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 285VU UT WOS:000085409600029 PM 10677480 ER PT J AU Scharff, LFV Hill, AL Ahumada, AJ AF Scharff, LFV Hill, AL Ahumada, AJ TI Discriminability measures for predicting readability of text on textured backgrounds SO OPTICS EXPRESS LA English DT Article ID NATURAL BACKGROUNDS; OBJECT DETECTION; NORMAL VISION; PSYCHOPHYSICS; LEGIBILITY; CONTRAST; MODELS AB Several discriminability measures were examined for their ability to predict reading search times for three levels of text contrast and a range of backgrounds (plain, a periodic texture, and four spatial-frequency-filtered textures created from the periodic texture). Search times indicate that these background variations only affect readability when the text contrast is low, and that spatial frequency content of the background affects readability. These results were not well predicted by the single variables of text contrast (Spearman rank correlation = -0.64) and background RMS contrast (0.08), but a global masking index and a spatial-frequency-selective masking index led to better predictions (-0.84 and -0.81, respectively). (C) 2000 Optical Society of America. C1 Stephen F Austin State Univ, Dept Psychol, Nacogdoches, TX 75962 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Scharff, LFV (reprint author), Stephen F Austin State Univ, Dept Psychol, Nacogdoches, TX 75962 USA. NR 20 TC 19 Z9 19 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1094-4087 J9 OPT EXPRESS JI Opt. Express PD FEB 14 PY 2000 VL 6 IS 4 BP 81 EP 91 PG 11 WC Optics SC Optics GA 285NT UT WOS:000085395700001 PM 12238520 ER PT J AU Sandford, SA Allamandola, LJ Geballe, TR AF Sandford, SA Allamandola, LJ Geballe, TR TI Spectroscopic detection of molecular hydrogen frozen in interstellar ices (Retraction of vol 286, pg 400, 1999) SO SCIENCE LA English DT Correction C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Gemini Observ, Hilo, HI 96720 USA. RP Sandford, SA (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 1 TC 0 Z9 0 U1 1 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD FEB 11 PY 2000 VL 287 IS 5455 BP 976 EP 976 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 282WU UT WOS:000085245400026 ER PT J AU Haiman, Z Knox, L AF Haiman, Z Knox, L TI Correlations in the far-infrared background SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; diffuse radiation; cosmology : theory; cosmology : observations; galaxies : evolution; galaxies : formation ID DUST; GALAXY; COBE AB We compute the expected angular power spectrum of the cosmic far infrared background (FIRB). We find that the signal due to source correlations dominates the shot noise for l less than or similar to 1000 and results in anisotropies with rms amplitudes [l(l + 1)C-l/2 pi](1/2) between 5% and 10% of the mean for l greater than or similar to 150. The angular power spectrum depends on several unknown quantities, such as the UV flux density evolution, optical properties of the dust, biasing of the sources of the FIRE, and cosmological parameters. However, when we require our models to reproduce the observed direct current level of the FIRE, we find that the anisotropy is at least a few percent in all cases. This anisotropy is detectable with proposed instruments, and its measurement will provide strong constraints on models of galaxy evolution and large-scale structure at redshifts up to at least z similar to 5. C1 NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Haiman, Z (reprint author), NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. NR 54 TC 45 Z9 45 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2000 VL 530 IS 1 BP 124 EP 132 DI 10.1086/308374 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 290YC UT WOS:000085704600009 ER PT J AU D'Cruz, NL O'Connell, RW Rood, RT Whitney, JH Dorman, B Landsman, WB Hill, RS Stecher, TP Bohlin, RC AF D'Cruz, NL O'Connell, RW Rood, RT Whitney, JH Dorman, B Landsman, WB Hill, RS Stecher, TP Bohlin, RC TI Hubble Space Telescope observations of new horizontal-branch structures in the globular cluster omega Centauri SO ASTROPHYSICAL JOURNAL LA English DT Article DE globular clusters : individual (omega Centauri); stars : evolution; stars : horizontal-branch; stars : mass loss; stars : Population II; ultraviolet : stars ID ELLIPTIC GALAXIES; ULTRAVIOLET UPTURN; STARS; PHOTOMETRY; ORIGIN AB The globular cluster omega Centauri contains the largest known population of very hot horizontal-branch (HB) stars. We have used the Hubble Space Telescope to obtain a far-UV/optical color-magnitude diagram of three fields in omega Cen. We find that over 30% of the HE objects are "extreme" HE or hot post-MB stars. The hot HE stars are not concentrated toward the cluster center, which argues against a dynamical origin for them. A wide gap in the color distribution of the hot HE stars appears to correspond to gaps found earlier in several other clusters. This suggests a common mechanism, probably related to giant branch mass loss. The diagram contains a significant population of hot sub-MB stars, which we interpret as the "blue-hook" objects previously predicted by D'Cruz et al. These are produced by late He flashes in stars which have undergone unusually large giant branch mass loss. The cluster omega Cen has a well-known spread of metal abundance, and our observations are consistent with a giant branch mass-loss efficiency which increases with metallicity. C1 Univ Sydney, Chatterton Astron Dept, Sch Phys A28, Sydney, NSW 2006, Australia. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Raytheon STX, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Univ Sydney, Chatterton Astron Dept, Sch Phys A28, Sydney, NSW 2006, Australia. EM noella@physics.usyd.edu.au; nrw@virginia.edu; rtr@virginia.edu; jw9w@virginia.edu; bd4r@virginia.edu; landsman@mpb.gsfc.nasa.gov; bhill@uit.gsfc.nasa.gov; stecher@uit.gsfc.nasa.gov; bohlin@fos.stsci.edu NR 40 TC 68 Z9 68 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2000 VL 530 IS 1 BP 352 EP 356 DI 10.1086/308375 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 290YC UT WOS:000085704600030 ER PT J AU Brickhouse, NS Dupree, AK Edgar, RJ Liedahl, DA Drake, SA White, NE Singh, KP AF Brickhouse, NS Dupree, AK Edgar, RJ Liedahl, DA Drake, SA White, NE Singh, KP TI Coronal structure and abundances of Capella from simultaneous EUVE and ASCA spectroscopy SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : spectroscopic; stars : abundances; stars : coronae; stars : individual (Capella); ultraviolet : stars; X-rays : stars ID X-RAY-EMISSION; CANUM-VENATICORUM BINARIES; EXTREME-ULTRAVIOLET OBSERVATIONS; CHROMOSPHERICALLY ACTIVE STARS; LOCAL INTERSTELLAR-MEDIUM; K-TYPE STARS; LINE EMISSION; COOL STARS; AR-LACERTAE; OUTER ATMOSPHERES AB We report analysis of the simultaneous 1996 March EUVE and ASCA observations of the spectroscopic binary Capella. The EUVE spectrum is dominated by lines of highly ionized Fe, requiring a continuous emission-measure distribution over a wide range of temperatures. The ASCA spectrum shows He-like line emission features of S, Si, and Mg, as well as unresolved L-shell emission lines of Fe and Ni and H-like and He-like Ne lines. The flux in these line features cannot be determined independently from the continuum flux. The ASCA spectrum is relatively soft, with few counts above 4 keV. The emission-measure distribution determined by Line-Based Analysis of the EUV Fe line intensities is well constrained from T(e)similar to 6 x 10(5) to 2 x 10(7) K, but it is not constrained above this range since Fe XXIV is the highest temperature line observed with EUVE. Since repeated observations of Capella by EUVE have shown that emission-line intensities of the hottest EUV-emitting material (Fe XXI to XXIV) vary by factors up to 4, the ASCA spectrum is important for extending the temperature coverage. Thus, the high-energy cut-off of the ASCA spectrum provides a constraint on the highest temperature emission measures. In principle, elemental abundances are determined from global fits to the ASCA spectrum; however, no well-fitting model has been found for the high signal-to-noise ASCA performance verification spectrum of Capella (1993 September 2). The newer ASCA spectrum of Capella (1996 March 3-4) shows a similar pattern of fitting difficulties. Using the EUVE measurements (1996 March 3-7) to constrain models, we have conducted sensitivity studies of the atomic data, source physics, and instrument calibration. The plasma spectral emission models (Raymond-Smith, MEKAL, SPEX) around 1.2 keV appear to have flux deficits relative to the observed ASCA count spectrum. New atomic models by Liedahl and Brickhouse, calculated with the HULLAC code, provide a set of lines-missing from the existing plasma codes-to fill in this flux deficit. Incorporating these additional lines dramatically improves the spectral model fits to the data, allowing reliable determination of elemental abundances. The successful application of the new atomic models to the Capella problem can have widespread implications, affecting spectral models of galaxies, cluster cooling flows, and supernova remnants, as well as other stellar coronae. Analysis with the new atomic models of the simultaneous ASCA and EUVE data confirms the previous EUVE results that the continuous emission-measure distribution of Capella has a strong enhancement at T(e)similar to 6 x 10(6) K. While a two-temperature model actually provides a better fit to the ASCA spectrum than the EUVE-derived continuous model, the EUVE data are not well fitted with only two temperatures. We find that the abundances of Mg, Si, S, and Fe are consistent with solar photospheric values, while Ne appears to be underabundant by a factor of similar to 3 to 4. C1 Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Tata Inst Fundamental Res, Dept Astron & Astrophys, Bombay 400005, Maharashtra, India. RP Brickhouse, NS (reprint author), Smithsonian Astrophys Observ, 60 Garden St, Cambridge, MA 02138 USA. RI White, Nicholas/B-6428-2012; OI White, Nicholas/0000-0003-3853-3462; Brickhouse, Nancy/0000-0002-8704-4473 NR 74 TC 85 Z9 86 U1 0 U2 6 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2000 VL 530 IS 1 BP 387 EP 402 DI 10.1086/308350 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 290YC UT WOS:000085704600034 ER PT J AU Rivera, EJ Lissauer, JJ AF Rivera, EJ Lissauer, JJ TI Stability analysis of the planetary system orbiting upsilon Andromedae SO ASTROPHYSICAL JOURNAL LA English DT Article DE celestial mechanics, stellar dynamics; methods : n-body simulations planetary systems; stars : individual (upsilon Andromedae) ID BEHAVIOR AB We present numerical orbital integrations designed to test the stability of the three planets detected in orbit around v Andromedae and possible smaller bodies orbiting in the system which have not yet been discovered. We find that some configurations are stable for at least 10(9) yr, whereas in other configurations planets can be ejected into interstellar space or crash into the star in less than 10(5) yr. The typical path to instability involves the outer planet exciting the eccentricity of the middle planet's orbit to such high values that it ventures close to the inner planet. In some stable systems, a secular resonance between the outer two planets prevents close approaches between them by aligning their longitudes of periastron. In relatively stable systems, test particles can survive for long times between the inner and middle planets as well as several AU exterior to the outer planet, but we could End no stable orbits between the middle and outer planets. C1 NASA, Ames Res Ctr, Div Space Sci 245 3, Moffett Field, CA 94035 USA. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. RP Rivera, EJ (reprint author), NASA, Ames Res Ctr, Div Space Sci 245 3, Moffett Field, CA 94035 USA. NR 20 TC 78 Z9 78 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2000 VL 530 IS 1 BP 454 EP 463 DI 10.1086/308345 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 290YC UT WOS:000085704600040 ER PT J AU Corbet, RHD Peele, AG AF Corbet, RHD Peele, AG TI The orbital period of the Be/neutron star binary RX J0812.4-3114 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : individual (RX J0812.4-3114); stars : neutron; X-rays : stars ID X-RAY PULSAR; TIMING EXPLORER AB We present the results of Rossi X-Ray Timing Explorer (RXTE) observations of the Be star X-ray binary system RX J0812.4-3114. A light curve obtained with the RXTE All-Sky Monitor (ASM) shows that the source is currently in an active state with outbursts occurring at approximately 80 day intervals. The source underwent a transition from an inactive state to this regular outburst state early in 1998. An observation of RX J0812.4-3114 was obtained with the RXTE Proportional Counter Array (PCA) dose to the time of a predicted maximum in 1999 March, and strong pulsations were detected at a period of 31.88 s. This confirms the result of an earlier PCA observation by Reig & Roche that was also obtained serendipitously near the predicted maximum flux of the 80 day period and also near the start of the current active state. We interpret the periodicity in the ASM light curve as indicating the orbital period of RX J0812.4-3114 with outbursts occurring around periastron passage. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 14 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2000 VL 530 IS 1 BP L33 EP L35 DI 10.1086/312485 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 290YE UT WOS:000085704800009 ER PT J AU Pritzl, B Smith, HA Catelan, M Sweigart, AV AF Pritzl, B Smith, HA Catelan, M Sweigart, AV TI RR Lyrae stars in NGC 6388 and NGC 6441: A new Oosterhoff group? SO ASTROPHYSICAL JOURNAL LA English DT Article DE globular clusters : individual (NGC 6388, NGC 6441); stars : variables : other (RR Lyrae) ID GLOBULAR-CLUSTER NGC-6388; BLUE FUNDAMENTAL EDGE; BVI-CCD PHOTOMETRY; VARIABLE-STARS; METALLICITY RELATION; OMEGA-CENTAURI; PERIOD GROUPS; LUMINOSITY; M15; AGE AB NGC 6388 and NGC 6441 are anomalies among Galactic globular clusters in that they cannot be readily placed into either Oosterhoff group I or Oosterhoff group II despite their significant numbers of RR Lyrae variables. The mean pulsation periods, [P-ab], of their RRab variables, at 0.71 and 0.76 days, respectively, are even larger than for Oosterhoff II clusters. Moreover, Oosterhoff II clusters are very metal poor, whereas NGC 6388 and NGC 6441 are the most metal-rich globular clusters known to contain RR Lyrae stars. The location of the NGC 6388 and NGC 6441 RRab variables in the period-amplitude diagram implies that the RR Lyrae stars in those two clusters are brighter than expected for their metallicities. Our results therefore indicate that a universal relationship may not exist between the luminosity and the metallicity of RR Lyrae variables. C1 Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Pritzl, B (reprint author), Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA. NR 36 TC 54 Z9 54 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2000 VL 530 IS 1 BP L41 EP L44 DI 10.1086/312482 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 290YE UT WOS:000085704800011 ER PT J AU Hixon, R Turkel, E AF Hixon, R Turkel, E TI Compact implicit MacCormack-type schemes with high accuracy SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE MacCormack-type scheme; compact differencing ID FINITE-DIFFERENCE SCHEMES; BOUNDARY-CONDITIONS AB In this work, the MacCormack methodology is extended to implicit compact differencing schemes. A prefactorization method is developed which splits the implicit matrix into two independent upper and lower matrices which are easier to invert. Using this method, a new class of high-order accurate compact MacCormack-type schemes is derived. Two fourth-order schemes are described, and results are shown for three linear and nonlinear CAA benchmark problems. (C) 2000 Academic Press. C1 NASA, Glenn Res Ctr, ICOMP, Cleveland, OH 44135 USA. Tel Aviv Univ, IL-69978 Tel Aviv, Israel. RP Hixon, R (reprint author), NASA, Glenn Res Ctr, ICOMP, Cleveland, OH 44135 USA. RI Turkel, Eli/F-6297-2011 OI Turkel, Eli/0000-0003-4273-0303 NR 20 TC 49 Z9 52 U1 1 U2 4 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD FEB 10 PY 2000 VL 158 IS 1 BP 51 EP 70 DI 10.1006/jcph.1999.6406 PG 20 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 286WX UT WOS:000085472800003 ER PT J AU Lyzenga, GA Panero, WR Donnellan, A AF Lyzenga, GA Panero, WR Donnellan, A TI Influence of anelastic surface layers on postseismic thrust fault deformation SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID NORTHRIDGE EARTHQUAKE; HALF-SPACE; AFTERSLIP; CYCLE AB We present the results of a systematic modeling study of postseismic deformation following blind thrust earthquakes. The results include qualitative and quantitative predictions' of the surface movement caused by relaxation in viscoelastic near-surface layers. Finite element forward models are used in conjunction with elastic dislocation inversions to characterize the postseismic deformation. A viscoelastic surface layer overlying a blind thrust fault in an elastic basement shows characteristic signatures of postseismic surface movement. Simple equivalent elastic dislocations located in the hanging wall wedge are found to provide an effective proxy for near-surface postseismic relaxation in two-dimensional numerical simulations. A model survey of a range of fault dip angles and layer geometries shows the time evolution and geometry of the proxy fault to be simply related to fault dip and sediment thickness. The results are of significance in the interpretation of postseismic Global Positioning System (CPS) strain data from the 1994 Northridge, California, earthquake and other similar events in regions characterized by poorly consolidated or otherwise anelastic layers overlying the brittle seismogenic zone. C1 Harvey Mudd Coll, Dept Phys, Claremont, CA 91711 USA. Univ Calif Berkeley, Dept Geol & Geophys, Berkeley, CA 94720 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Lyzenga, GA (reprint author), Harvey Mudd Coll, Dept Phys, Claremont, CA 91711 USA. EM lyzenga@hmc.edu; panero@uclink4.berkeley.edu; andrea@cobra.jpl.nasa.gov RI Panero, Wendy/C-9602-2009 NR 18 TC 15 Z9 15 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD FEB 10 PY 2000 VL 105 IS B2 BP 3151 EP 3157 DI 10.1029/1999JB900269 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 282GC UT WOS:000085208800032 ER PT J AU Seiff, A AF Seiff, A TI Astronomy - Dynamics of Jupiter's atmosphere SO NATURE LA English DT Editorial Material C1 San Jose State Univ Fdn, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Seiff, A (reprint author), San Jose State Univ Fdn, Mail Stop 245-1, Moffett Field, CA 94035 USA. NR 7 TC 6 Z9 7 U1 0 U2 1 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 10 PY 2000 VL 403 IS 6770 BP 603 EP + DI 10.1038/35001171 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 283RD UT WOS:000085288200030 ER PT J AU Gierasch, PJ Ingersoll, AP Banfield, D Ewald, SP Helfenstein, P Simon-Miller, A Vasavada, A Breneman, HH Senske, DA AF Gierasch, PJ Ingersoll, AP Banfield, D Ewald, SP Helfenstein, P Simon-Miller, A Vasavada, A Breneman, HH Senske, DA CA Galileo Imaging Team TI Observation of moist convection in Jupiter's atmosphere SO NATURE LA English DT Article ID GALILEO AB The energy source driving Jupiter's active meteorology is not understood(1). There are two main candidates: a poorly understood internal heat source and sunlight. Here we report observations of an active storm system possessing both lightning and condensation of water. The storm has a vertical extent of at least 50 km and a length of about 4,000 km. Previous observations(2,3) of lightning on Jupiter have revealed both its frequency of occurrence and its spatial distribution, but they did not permit analysis of the detailed cloud structure and its dynamics. The present observations reveal the storm (on the day side of the planet) at the same location and within just a few hours of a lightning detection (on the night side). We estimate that the total vertical transport of heat by storms like the one observed here is of the same order as the planet's internal heat source. We therefore conclude that moist convection-similar to large clusters of thunderstorm cells on the Earth-is a dominant factor in converting heat flow into kinetic energy in the jovian atmosphere. C1 Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90025 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gierasch, PJ (reprint author), Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. RI Simon, Amy/C-8020-2012; OI Simon, Amy/0000-0003-4641-6186; Banfield, Don/0000-0003-2664-0164 NR 15 TC 95 Z9 96 U1 2 U2 11 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 10 PY 2000 VL 403 IS 6770 BP 628 EP 630 DI 10.1038/35001017 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 283RD UT WOS:000085288200043 ER PT J AU Siegert, MJ Kwok, R Mayer, C Hubbard, B AF Siegert, MJ Kwok, R Mayer, C Hubbard, B TI Water exchange between the subglacial Lake Vostok and the overlying ice sheet SO NATURE LA English DT Article ID CENTRAL EAST-ANTARCTICA; STATION AB It has now been known for several years that a 200-km-long lake, called Lake Vostok, lies beneath the ice sheet on which sits Vostok Station in Antarctica(1-5), The conditions at the base of the ice sheet above this subglacial lake can provide information about the environment within the lake, including the likelihood that it supports life(2). Here we present an analysis of the ice-sheet structure from airborne 60-MHz radar studies, which indicates that distinct zones of basal ice loss and accretion occur at the ice-water interface. Subglacial melting and net ice loss occur in the north of the lake and across its 200-km-long western margin, whereas about 150 m of ice is gained by subglacial freezing in the south. This indicates that significant quantities of water are exchanged between the base of the ice sheet and the lake waters, which will enrich the lake with gas hydrates, cause sediment deposition and encourage circulation of the lake water. C1 Univ Bristol, Sch Geol Sci, Bristol Glaciol Ctr, Bristol BS8 1SS, Avon, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Alfred Wegener Inst Polar & Marine Res, Dept Geophys, Bremerhaven, Germany. Univ Wales, Inst Geog & Earth Sci, Ctr Glaciol, Aberystwyth SY23 3DB, Dyfed, Wales. RP Siegert, MJ (reprint author), Univ Bristol, Sch Geol Sci, Bristol Glaciol Ctr, Bristol BS8 1SS, Avon, England. RI Siegert, Martin/A-3826-2008; Kwok, Ron/A-9762-2008 OI Siegert, Martin/0000-0002-0090-4806; Kwok, Ron/0000-0003-4051-5896 NR 13 TC 53 Z9 54 U1 2 U2 7 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 10 PY 2000 VL 403 IS 6770 BP 643 EP 646 DI 10.1038/35001049 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 283RD UT WOS:000085288200049 ER PT J AU Orito, S Maeno, T Matsunaga, H Abe, K Anraku, K Asaoka, Y Fujikawa, M Imori, M Ishino, M Makida, Y Matsui, N Matsumoto, H Mitchell, J Mitsui, T Moiseev, A Motoki, M Nishimura, J Nozaki, M Ormes, J Saeki, T Sanuki, T Sasaki, M Seo, ES Shikaze, Y Sonoda, T Streitmatter, R Suzuki, J Tanaka, K Ueda, I Yajima, N Yamagami, T Yamamoto, A Yoshida, T Yoshimura, K AF Orito, S Maeno, T Matsunaga, H Abe, K Anraku, K Asaoka, Y Fujikawa, M Imori, M Ishino, M Makida, Y Matsui, N Matsumoto, H Mitchell, J Mitsui, T Moiseev, A Motoki, M Nishimura, J Nozaki, M Ormes, J Saeki, T Sanuki, T Sasaki, M Seo, ES Shikaze, Y Sonoda, T Streitmatter, R Suzuki, J Tanaka, K Ueda, I Yajima, N Yamagami, T Yamamoto, A Yoshida, T Yoshimura, K TI Precision measurement of cosmic-ray antiproton spectrum SO PHYSICAL REVIEW LETTERS LA English DT Article ID SOLAR MINIMUM; BLACK-HOLES; FLUX; MODULATION; ATMOSPHERE AB The energy spectrum of cosmic-ray antiprotons ((p) over bar's) has been measured in the range 0.18-3.56 GeV, based on 458 (p) over bar's collected by BESS in a recent solar-minimum period. We have detected for the first time a characteristic peak at 2 GeV of (p) over bar's originating from cosmic-ray interactions with the interstellar gas. The peak spectrum is reproduced by theoretical calculations, implying that the propagation models are basically correct and that different cosmic-ray species undergo a universal propagation. Future BESS data with still higher statistics will allow us to study the solar modulation and the propagation in detail and to search for primary (p) over bar components. C1 Univ Tokyo, Tokyo 1130033, Japan. High Energy Accelerator Res Org, KEK, Tsukuba, Ibaraki 3050801, Japan. Kobe Univ, Kobe, Hyogo 6578501, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Kyoto Univ, Kyoto 6068502, Japan. RP Orito, S (reprint author), Univ Tokyo, Tokyo 1130033, Japan. RI MOTOKI, Masakazu/B-4212-2009; OI Seo, Eun-Suk/0000-0001-8682-805X NR 28 TC 236 Z9 237 U1 0 U2 4 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD FEB 7 PY 2000 VL 84 IS 6 BP 1078 EP 1081 DI 10.1103/PhysRevLett.84.1078 PG 4 WC Physics, Multidisciplinary SC Physics GA 281UE UT WOS:000085178500005 ER PT J AU Reinholtz, K AF Reinholtz, K TI Java will be faster than C++ SO ACM SIGPLAN NOTICES LA English DT Article DE Java, C; C plus; compiler performance; compilers; dynamic compilation; comparative performance of Java and C plus AB This paper shows that it is possible for Java to have better general performance than C++, and that it is likely that this will actually occur. Java performance can exceed that of C-ti because dynamic compilation gives the Java compiler access to runtime information not available to a C++ compiler. This will occur because the rapidly growing market for embedded systems will be driven to extend battery life. Since each CPU clock cycle consumes some energy, battery life is extended by improving performance, thus achieving more computation per clock cycle. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Reinholtz, K (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 4 Z9 4 U1 0 U2 1 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 USA SN 0362-1340 J9 ACM SIGPLAN NOTICES JI ACM Sigplan Not. PD FEB PY 2000 VL 35 IS 2 BP 25 EP 28 DI 10.1145/345105.352548 PG 4 WC Computer Science, Software Engineering SC Computer Science GA 297XB UT WOS:000086107000003 ER PT J AU Han, JG Lin, YL Schowalter, DG Arya, SP AF Han, JG Lin, YL Schowalter, DG Arya, SP TI Large eddy simulation of aircraft wake vortices within homogeneous turbulence: Crow instability SO AIAA JOURNAL LA English DT Article ID AMBIENT TURBULENCE; TRAILING VORTICES; BOUNDARY-LAYER; VORTEX; DECAY; MODEL AB Ambient atmospheric turbulence effects on aircraft wake vortices are studied using a validated large eddy simulation model. Our results confirm that the most amplified wavelength of the Crow instability and the lifetime of wake vortices are significantly influenced by ambient turbulence (Crow, S. C., "Stability Theory for a Pair of Trailing Vortices,'' AlAA Journal, Vol. 8, No. 12, 1970, pp. 2172-2179). The Crow instability becomes well developed in most atmospheric turbulence levels, but in strong turbulence the vortex pair deforms more irregularly due to turbulence advection. The most amplified wavelength of the instability decreases with increasing dimensionless turbulence intensity eta, although it increases with increasing turbulence integral length scale. The vortex lifespan is controlled primarily by eta and decreases with increasing eta, whereas the effect of integral scale of turbulence on vortex lifespan is of minor importance. The lifespan is estimated to be about 40% larger than Crow and Bate's predicted value (Crow, S. C., and Bate, E. R,, "Lifespan of Trailing Vortices on a Turbulent Atmosphere," Journal of Aircraft, Vol. 13, No. 7, 1976, pp. 476-482) but in agreement with Sarpkaya's recent modification (Sarpkaya, T., "Decay of Wake Vortices of Large Aircraft,'' AlAA Journal, Vol. 36, No. 9, 1998, pp. 1671-1679) to Crow and Bate's theory. This larger lifespan is also supported by data from water tank experiments and direct numerical simulations. There appears to be a possibility that the scatter in vortex lifespans due to ambient turbulence alone decreases with increasing Reynolds number, whereas larger scatter of lifespans in Right tests may result from other factors such as stratification, wind shear, and inhomogeneous ambient turbulence. C1 N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Raleigh, NC 27695 USA. NASA, Langley Res Ctr, Flight Dynam & Control Div, Hampton, VA 23681 USA. RP Han, JG (reprint author), N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Box 8208, Raleigh, NC 27695 USA. NR 31 TC 8 Z9 8 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 2000 VL 38 IS 2 BP 292 EP 300 DI 10.2514/2.956 PG 9 WC Engineering, Aerospace SC Engineering GA 281VR UT WOS:000085182600013 ER PT J AU Ribner, HS AF Ribner, HS TI Comment on "Jet mixing noise from fine-scale turbulence" SO AIAA JOURNAL LA English DT Editorial Material ID FLOW C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Ribner, HS (reprint author), Univ Toronto, Inst Aerosp Studies, 4925 Dufferin St, Toronto, ON M3H 5T6, Canada. NR 11 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 2000 VL 38 IS 2 BP 377 EP 378 DI 10.2514/2.970 PG 2 WC Engineering, Aerospace SC Engineering GA 281VR UT WOS:000085182600026 ER PT J AU Thrasher, TN Chen, HG Keil, LC AF Thrasher, TN Chen, HG Keil, LC TI Arterial baroreceptors control plasma vasopressin responses to graded hypotension in conscious dogs SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE angiotensin; antidiuretic hormone; cardiac receptors; atrial receptors; ventricular receptors; blood volume; blood pressure ID RENIN SECRETION; HEMORRHAGE; RELEASE; DENERVATION; INHIBITION; RECEPTORS; BLOCKADE; PRESSURE AB We studied the role of cardiac and arterial baroreceptors in the reflex control of arginine vasopressin (AVP) and renin secretion during graded hypotension in conscious dog;. The dogs were prepared with Silastic cuffs on the thoracic inferior vena cava and catheters in the pericardial space. Each experiment consisted of a control period followed by four periods of inferior vena caval constriction, during which mean arterial pressure (MAP) was reduced in increments of similar to 10 mmHg. The hormonal responses were measured in five dogs under four treatment conditions: 1) intact, 2) acute cardiac denervation (CD) by intrapericardial infusion of procaine, 3) after sinoaortic denervation (SAD), and 4) during combined SAD+CD. The individual slopes relating MAP to plasma AVP and plasma renin activity (PRA) were used to compare the treatment effects using a 2 x 2 factorial: analysis. There was a significant (P < 0.01) effect of SAD on the slope relating plasma AVP to MAP but no effect of CD and no SAD X CD interaction. In contrast, the slope relating PRA and MAP was increased (P < 0.05) by SAD but was not affected by CD. These results support the hypothesis that stimulation of AVP secretion in response to graded hypotension is primarily driven by unloading arterial baroreceptors in the dog. C1 Univ Maryland, Dept Surg, Baltimore, MD 21201 USA. Maple House, Santa Cruz, CA 95062 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Thrasher, TN (reprint author), Univ Maryland, Dept Surg, 10 S Pine St,Rm 400, Baltimore, MD 21201 USA. FU NHLBI NIH HHS [HL-41313] NR 26 TC 17 Z9 19 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regul. Integr. Comp. Physiol. PD FEB PY 2000 VL 278 IS 2 BP R469 EP R475 PG 7 WC Physiology SC Physiology GA 283CG UT WOS:000085258100023 PM 10666149 ER PT J AU Arepalli, S Nikolaev, P Holmes, W Scott, CD AF Arepalli, S Nikolaev, P Holmes, W Scott, CD TI Diagnostics of laser-produced plume under carbon nanotube growth conditions SO APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING LA English DT Article ID DIAMETER DISTRIBUTION; ABLATION; VAPORIZATION; TEMPERATURE; MECHANISM AB This paper presents diagnostic data obtained from the plume of a graphite composite target during carbon nano-tube production by the double-pulse laser oven method. The in situ emission spectrum (300 to 650 nm) is recorded at different locations upstream of the target and at different delay times from the lasers (IR and green). Spectral features are identified as emissions from C-2 (Swan System: d (3) Pi(g)-a (3) Pi(u)) and C-3 (Comet Head System: A (1) Pi(u)-X (1) Sigma(u)(+)). Experimental spectra are compared with computed spectra to estimate vibrational temperatures of excited state C-2 in the range of 2500 to 4000 K. The temporal evolution of the 510-nm band of C-2 is monitored for two target positions in various locations, which shows confinement of the plume in the inner tube and increase in plume velocity with temperature. The excitation spectra of C-2 are obtained by using a dye laser to pump the (0,1) transition of the Swan System and collecting the laser-induced fluorescence signal from C-2. These are used to obtain "ground-state" rotational and vibrational temperatures which are close to the oven temperature. Images of the plume are also collected and are compared with the spectral measurements. C1 Lockheed Martin, GB Tech, Houston, TX 77058 USA. NASA, JSC, Houston, TX 77058 USA. RP Arepalli, S (reprint author), Lockheed Martin, GB Tech, 2400 NASA Rd 1,Mail Stop C61, Houston, TX 77058 USA. RI Arepalli, Sivaram/A-5372-2010; Nikolaev, Pavel/B-9960-2009 NR 26 TC 45 Z9 46 U1 0 U2 6 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0947-8396 J9 APPL PHYS A-MATER JI Appl. Phys. A-Mater. Sci. Process. PD FEB PY 2000 VL 70 IS 2 BP 125 EP 133 DI 10.1007/s003390050024 PG 9 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA 295EB UT WOS:000085952800002 ER PT J AU Bottcher, M Bloom, SD AF Bottcher, M Bloom, SD TI Analyzing the multiwavelength spectrum of BL Lacertae during the 1997 July outburst SO ASTRONOMICAL JOURNAL LA English DT Article DE BL Lacertae objects : individual (BL Lacertae); galaxies : active; gamma rays ID ACTIVE GALACTIC NUCLEI; CORRELATED GAMMA-RAY; SELF-COMPTON MODEL; BLAZAR 3C-279; EMISSION; RADIATION; FLARE; RADIO; ACCELERATION; VARIABILITY AB The multiwavelength spectrum of BL Lacertae during its July 1997 outburst is analyzed in terms of different variations of the homogeneous leptonic jet model for the production of high-energy radiation from blazers. We find that a two-component gamma-ray spectrum, consisting of a synchrotron self-Compton and an external Compton component, is required in order to yield an acceptable fit to the broadband spectrum. Our analysis indicates that in BL Lac, unlike other BL Lac objects, the broad emission-line region plays an important role for the high-energy emission. Several alternative blazar jet models are briefly discussed. In the Appendix, we describe the formalism in which this latter process is treated in the previously developed blazar jet simulation code which we use. C1 Rice Univ, Dept Space Phys & Astron, Houston, TX 77005 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Bottcher, M (reprint author), Rice Univ, Dept Space Phys & Astron, MS 108,6100 S Main St, Houston, TX 77005 USA. NR 56 TC 53 Z9 55 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2000 VL 119 IS 2 BP 469 EP 477 DI 10.1086/301201 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 283KX UT WOS:000085275700004 ER PT J AU Gardner, JP Baum, SA Brown, TM Carollo, CM Christensen, J Dashevsky, I Dickinson, ME Espey, BR Ferguson, HC Fruchter, AS Gonnella, AM Gonzalez-Lopezlira, RA Hook, RN Kaiser, ME Martin, CL Sahu, KC Savaglio, S Smith, TE Teplitz, HI Williams, RE Wilson, J AF Gardner, JP Baum, SA Brown, TM Carollo, CM Christensen, J Dashevsky, I Dickinson, ME Espey, BR Ferguson, HC Fruchter, AS Gonnella, AM Gonzalez-Lopezlira, RA Hook, RN Kaiser, ME Martin, CL Sahu, KC Savaglio, S Smith, TE Teplitz, HI Williams, RE Wilson, J TI The Hubble Deep Field South: STIS imaging SO ASTRONOMICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : evolution; galaxies : statistics; surveys ID STAR-FORMATION HISTORY; SPACE-TELESCOPE; PHOTOMETRY; GALAXIES AB We present the imaging observations made with the Space Telescope Imaging Spectrograph (STIS) of the Hubble Deep Field South. The field was imaged in four bandpasses: a clear CCD bandpass for 156 ks, a long-pass filter for 22-25 ks pixel(-1) typical exposure, a near-UV bandpass for 23 ks, and a far-UV bandpass for 52 ks. The clear, visible image is the deepest observation ever made in the UV-optical wavelength region, reaching a 10 sigma AB magnitude of 29.4 for an object of area 0.2 arcsec(2). The field contains QSO J2233-606, the target of the STIS spectroscopy, and extends 50 " x 50 " for the visible images, and 25 " x 25 " for the ultraviolet images. We present the images, catalog of objects, and galaxy counts obtained in the field. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Space Telescope European Coordinating Facil, D-85748 Garching, Germany. RP Gardner, JP (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. OI Espey, Brian/0000-0002-2457-1380 NR 28 TC 41 Z9 41 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2000 VL 119 IS 2 BP 486 EP 508 DI 10.1086/301215 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 283KX UT WOS:000085275700006 ER PT J AU Soifer, BT Neugebauer, G Matthews, K Egami, E Becklin, EE Weinberger, AJ Ressler, M Werner, MW Evans, AS Scoville, NZ Surace, JA Condon, JJ AF Soifer, BT Neugebauer, G Matthews, K Egami, E Becklin, EE Weinberger, AJ Ressler, M Werner, MW Evans, AS Scoville, NZ Surace, JA Condon, JJ TI High resolution mid-infrared imaging of ultraluminous infrared galaxies SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : individual (Arp 220, Markarian 231, Markarian 273, UGC 5101, IRAS 05189-2524; IRAS 08572+3915, IRAS 17208-0014); infrared radiation ID SAMPLE AB Observations of ultraluminous infrared galaxies (ULIRGs) with an achieved resolution approaching the diffraction limit in the mid-infrared from 8 to 25 mu m using the Keck Telescopes are reported. We find extremely compact structures, with spatial scales of less than 0 ".3 (diameter) in six of the seven ULIRGs observed. These compact sources emit between 30% and 100% of the mid-infrared energy from these galaxies. We have utilized the compact mid-infrared structures as a diagnostic of whether an AGN or a compact (100-300 pc) starburst is the primary power source in these ULIRGs. In Markarian 231, the upper limit on the diameter of the 12.5 mu m source, 0 ".13, shows that the size of the infrared source must increase with increasing wavelength, consistent with AGN models. In IRAS 05189-2524 and IRAS 08572+3915 there is strong evidence that the source size increases with increasing wavelength. This suggests heating by a central source rather than an extended luminosity source, consistent with the optical classification as an AGN. The compact mid-infrared sources seen in the other galaxies cannot be used to distinguish the ultimate luminosity source. If these ULIRGs are powered by compact starbursts, the star formation rates seen in the central few hundred parsecs far exceed the global rates seen in nearby starburst galaxies, and approach the surface brightness of individual clusters in nearby starburst galaxies. C1 CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. CALTECH, SIRTF Sci Ctr, Pasadena, CA 91125 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. RP Soifer, BT (reprint author), CALTECH, Palomar Observ, 320-47, Pasadena, CA 91125 USA. OI Weinberger, Alycia/0000-0001-6654-7859 NR 48 TC 164 Z9 164 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2000 VL 119 IS 2 BP 509 EP 523 DI 10.1086/301233 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 283KX UT WOS:000085275700007 ER PT J AU Eskridge, PB Frogel, JA Pogge, RW Quillen, AC Davies, RL DePoy, DL Houdashelt, ML Kuchinski, LE Ramirez, SV Sellgren, K Terndrup, DM Tiede, GP AF Eskridge, PB Frogel, JA Pogge, RW Quillen, AC Davies, RL DePoy, DL Houdashelt, ML Kuchinski, LE Ramirez, SV Sellgren, K Terndrup, DM Tiede, GP TI The frequency of barred spiral galaxies in the near-infrared SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : fundamental parameters; galaxies : spiral; galaxies : statistics; galaxies : structure ID MORPHOLOGICAL CLASSIFICATION; QUANTITATIVE MORPHOLOGY; SURFACE PHOTOMETRY; VIRGO CLUSTER; DISK GALAXIES; STELLAR BARS; DARK-MATTER; IMAGES; BULGES; SIMULATIONS AB We have determined the fraction of barred galaxies in the H-band for a statistically well-defined sample of 186 spirals drawn from the Ohio State University Bright Spiral Galaxy Survey. We find 56% of our sample to be strongly barred in the H band while another 16% is weakly barred. Only 27% of our sample is unbarred in the near-infrared. The RC3 and the Carnegie Atlas of Galaxies both classify only about 30% of our sample as strongly barred. Thus strong bars are nearly twice as prevalent in the near-infrared as in the optical. The frequency of genuine optically hidden bars is significant but lower than many claims in the literature: 40% of the galaxies in our sample that are classified as unbarred in the RC3 show evidence for a bar in the H band while the Carnegie Atlas lists this fraction as 66%. Our data reveal no significant trend in bar fraction as a function of morphology in either the optical or H band. Optical surveys of high-redshift galaxies may be strongly biased against finding bars, as bars are increasingly difficult to detect at bluer rest wavelengths. C1 Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Univ Durham, Dept Phys, Durham DH1 3LE, England. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. CALTECH, NASA, IPAC, Pasadena, CA 91125 USA. Natl Opt Astron Observ, Tucson, AZ 85719 USA. RP Eskridge, PB (reprint author), Ohio State Univ, Dept Astron, 174 W 18Th Ave, Columbus, OH 43210 USA. EM eskridge@astronomy.ohio-state.edu; frogel@astronomy.ohio-state.edu NR 51 TC 267 Z9 270 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2000 VL 119 IS 2 BP 536 EP 544 DI 10.1086/301203 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 283KX UT WOS:000085275700009 ER PT J AU Rodriguez, LF Delgado-Arellano, VG Gomez, Y Reipurth, B Torrelles, JM Noriega-Crespo, A Raga, AC Canto, J AF Rodriguez, LF Delgado-Arellano, VG Gomez, Y Reipurth, B Torrelles, JM Noriega-Crespo, A Raga, AC Canto, J TI New VLA observations of the HH 1-2 region: Evidence for density enhancements moving along the axis of the VLA 1 radio jet SO ASTRONOMICAL JOURNAL LA English DT Article DE ISM : individual (HH 1, HH 2); ISM : jets and outflows; stars : pre-main-sequence ID HERBIG-HARO OBJECTS; EXCITING SOURCES; PROPER MOTIONS; CONTINUUM EMISSION; SPECTRAL INDEXES; HH-1-2 REGION; RESOLUTION; SYSTEM; SPECTROSCOPY; OUTFLOWS AB Using the Very Large Array, we have carried out new, sensitive radio continuum observations at 6 and 3.6 cm of the HH 1-2 region. The comparison between the 6 cm maps made from data taken in 1986.2 and 1992.9 indicates that VLA 1, the exciting source of the HH 1-2 flow, has suffered a morphological change that is attributed to the motion of a symmetric pair of knots along the axis of the radio jet. The proper motion of these knots, that are observed within 1 " from the embedded star, are consistent with the values found for optical and near-IR jets several arcseconds away. We tentatively propose that one of the knots observed in the 1986.2 radio data has emerged out of the heavily obscured region around VLA 1 as a near-infrared knot in the 1998.2 data of Reipurth and coworkers. This result supports the interpretation that the knots are formed by intrinsic processes in the acceleration and collimation of the flow or by shocks caused by a variable jet running into itself, and not by instabilities or sheer with the surrounding medium. The source VLA 3, associated with an H2O maser and powering a molecular outflow, also shows morphological changes that we attribute to the turn-on of a new, faint component. Our sensitive 3.6 cm map reveals the presence of a new source, VLA 4, that coincides positionally with the infrared source 3 of Reipurth and coworkers. Finally, we derive a proper motion for HH 1F that agrees closely with the optical values. In the case of HH 2 the complexity of the source hampers a detailed comparison with the optical proper motions. C1 Univ Nacl Autonoma Mexico, Inst Astron, Mexico City 04510, DF, Mexico. Univ Michoacana San Nicolas de Hidalgo, Inst Fis & Matemat, Morelia 58040, Michoacan, Mexico. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. CSIC, IEEC, E-08034 Barcelona, Spain. CALTECH, Ctr Infrared Proc & Anal, JPL, Pasadena, CA 91125 USA. RP Rodriguez, LF (reprint author), Univ Nacl Autonoma Mexico, Inst Astron, Apdo Postal 70-264, Mexico City 04510, DF, Mexico. OI Torrelles, Jose Maria/0000-0002-6896-6085 NR 41 TC 47 Z9 49 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2000 VL 119 IS 2 BP 882 EP 889 DI 10.1086/301231 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 283KX UT WOS:000085275700035 ER PT J AU Queloz, D Mayor, M Weber, L Blecha, A Burnet, M Confino, B Naef, D Pepe, F Santos, N Udry, S AF Queloz, D Mayor, M Weber, L Blecha, A Burnet, M Confino, B Naef, D Pepe, F Santos, N Udry, S TI The CORALIE survey for southern extra-solar planets I. A planet orbiting the star Gliese 86 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : planetary systems; stars : individual : GJ 86; stars : low-mass, brown dwarfs; stars : binaries : spectroscopic ID GIANT PLANETS; MIGRATION; SYSTEMS; DISK AB A 4M(J) planet with a 15.8 day orbital period has been detected from very precise radial velocity measurements with the CORALIE echelle spectrograph. A second remote and more massive companion has also been detected. All the planetary companions so far detected in orbit closer than 0.08 AU have a parent star with a statistically higher metal content compared to the metallicity distribution of other stars with planets. Different processes occuring during their formation may provide a possible explanation for this observation. C1 Observ Geneva, CH-1290 Sauverny, Switzerland. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Queloz, D (reprint author), Observ Geneva, 51 Ch Maillettes, CH-1290 Sauverny, Switzerland. EM Didier.Queloz@obs.unige.ch RI Santos, Nuno/E-9957-2011 OI Santos, Nuno/0000-0003-4422-2919 NR 27 TC 235 Z9 236 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD FEB PY 2000 VL 354 IS 1 BP 99 EP 102 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 295FH UT WOS:000085955700025 ER PT J AU Masetti, N Palazzi, E Pian, E Hunt, LK Mendez, M Frontera, F Amati, L Vreeswijk, PM Rol, E Galama, TJ van Paradijs, J Antonelli, LA Nicastro, L Feroci, M Marconi, G Piro, L Costa, E Kouveliotou, C Castro-Tirado, AJ Falomo, R Augusteijn, T Bohnhardt, H Lidman, C Vanzi, L Merrill, KM Kaminsky, CD van der Klis, M Heemskerk, MHM van der Hooft, F Kuulkers, E Pedersen, H Benetti, S AF Masetti, N Palazzi, E Pian, E Hunt, LK Mendez, M Frontera, F Amati, L Vreeswijk, PM Rol, E Galama, TJ van Paradijs, J Antonelli, LA Nicastro, L Feroci, M Marconi, G Piro, L Costa, E Kouveliotou, C Castro-Tirado, AJ Falomo, R Augusteijn, T Bohnhardt, H Lidman, C Vanzi, L Merrill, KM Kaminsky, CD van der Klis, M Heemskerk, MHM van der Hooft, F Kuulkers, E Pedersen, H Benetti, S TI Near-infrared detection and optical follow-up of the GRB990705 afterglow SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE gamma rays : bursts; radiation mechanisms : non-thermal; galaxies : general ID GAMMA-RAY BURST; STANDARD STARS; GALAXY; EXTINCTION; SYSTEM AB Optical and near-infrared observations of the GRB990705 error box were carried out with ESO telescopes at La Silla and Paranal in Chile and with the NOAO SPIREX 0.6-meter telescope in Antarctica. We detected the counterpart of this GRB in the near-infrared H band and optical V band. The power-law decline of the near-infrared lightcurve is rather steep with a decay index alpha similar or equal to 1.7 in the first hours, and a possible steepening after one day. Broadband spectral analysis of the optical/near-infrared afterglow suggests that this GRB took place in a high density environment. A deep optical image obtained at Antu (VLT-UT1) about 5 days after the GRB trigger shows at the position of the transient an extended object which might be the host galaxy of GRB990705. C1 CNR, Ist Tecnol & Studio Radiazioni Extraterrestri, I-40129 Bologna, Italy. CNR, Ctr Astron Infrarossa & Studio Mezzo Interstellar, I-50125 Florence, Italy. Univ Amsterdam, Astron Inst, NL-1098 SJ Amsterdam, Netherlands. Natl Univ La Plata, Fac Ciencias Astron & Geofis, RA-1900 La Plata, Argentina. Univ Ferrara, Dipartmento Fis, I-44100 Ferrara, Italy. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Osserv Astron Roma, I-00040 Monte Porzio Catone, Italy. CNR, Ist Fis Cosm Applicazioni Informat, I-90146 Palermo, Italy. CNR, Ist Fis Cosm Applicaz Informat, I-00131 Rome, Italy. Univ Space Res Assoc, Huntsville, AL 35800 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. CSIC, Inst Astrofis Andalucia, Granada 18080, Spain. INTA, Lab Astrofis Espacial & Fis Fundamental, Madrid 28080, Spain. Osserv Astron Padova, I-35122 Padua, Italy. European So Observ, Santiago, Chile. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Univ Chicago, Yerkes Observ, Ctr Astrophys Res Astron, Williams Bay, WI 53191 USA. Space Res Org Netherlands, NL-3584 CA Utrecht, Netherlands. Univ Utrecht, Astron Inst, NL-3507 TA Utrecht, Netherlands. Copenhagen Univ Observ, DK-2100 Copenhagen, Denmark. Ctr Galileo Galilei, Telescopio Nazl Galileo, Santa Cruz de la Palma 38700, Canary Isl, Spain. RP Masetti, N (reprint author), CNR, Ist Tecnol & Studio Radiazioni Extraterrestri, Via Gobetti 101, I-40129 Bologna, Italy. EM masetti@tesre.bo.cnr.it RI Mendez, Mariano/C-8011-2012; Galama, Titus/D-1429-2014; Vanzi, Leonardo/D-1381-2014; PIRO, LUIGI/E-4954-2013; Nicastro, Luciano/F-5866-2015; Palazzi, Eliana/N-4746-2015; Amati, Lorenzo/N-5586-2015; OI Castro-Tirado, A. J./0000-0003-2999-3563; Falomo, Renato/0000-0003-4137-6541; Hunt, Leslie/0000-0001-9162-2371; Pian, Elena/0000-0001-8646-4858; Costa, Enrico/0000-0003-4925-8523; Feroci, Marco/0000-0002-7617-3421; Palazzi, Eliana/0000-0002-8691-7666; Mendez, Mariano/0000-0003-2187-2708; Galama, Titus/0000-0002-1036-396X; PIRO, LUIGI/0000-0003-4159-3984; Nicastro, Luciano/0000-0001-8534-6788; Amati, Lorenzo/0000-0001-5355-7388; Benetti, Stefano/0000-0002-3256-0016 NR 52 TC 40 Z9 41 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD FEB PY 2000 VL 354 IS 2 BP 473 EP 479 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 294QH UT WOS:000085921500012 ER PT J AU Hujeirat, A Camenzind, M Yorke, HW AF Hujeirat, A Camenzind, M Yorke, HW TI Protostellar masses versus ionization fraction in star-forming clouds SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE magnetic fields; Magnetohydrodynamics (MHD); stars : formation; ISM : clouds; ISM : magnetic fields ID AMBIPOLAR DIFFUSION; MOLECULAR CLOUDS; CORES; CONTRACTION; COLLAPSE; SUPPORT AB We study the dynamical evolution of self-gravitating magnetic cloud cores with an implicit MHD code for different dependencies of the ionization fraction on density. Assuming magnetically subcritical cloud cores initially similar in every respect except for the degree of ionization, we show that moderately and highly ionized cores tend to form more massive objects than their weakly ionized counterparts. Including the effects of rotation and/or more efficient cooling enhances this difference. Whereas the collapse of a weakly ionized core occurs on the free-fall time scale and independent of the boundary conditions, the onset of collapse in moderately or highly ionized media depends strongly on the flow of material along magnetic field lines through the boundaries. We discuss the possibility that fast, large scale gravitationally induced inflows are likely to occur along the lines of strong magnetic fields threading a highly ionized self-gravitating core. Based on our numerical results, we conclude that the ratio of mass to magnetic flux should be considered in combination with ionization fraction in order to estimate the mass of the object which can be expected to result from non-isolated core collapse. C1 Landessternwarte Konigstuhl, D-69117 Heidelberg, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hujeirat, A (reprint author), Landessternwarte Konigstuhl, D-69117 Heidelberg, Germany. NR 30 TC 3 Z9 3 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD FEB PY 2000 VL 354 IS 3 BP 1041 EP 1052 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 304PA UT WOS:000086491600035 ER PT J AU Klassen, A Aurass, H Mann, G Thompson, BJ AF Klassen, A Aurass, H Mann, G Thompson, BJ TI Catalogue of the 1997 SOHO-EIT coronal transient waves and associated type II radio burst spectra SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE Sun : corona; flares; radio radiation; shock waves ID EMISSION AB We compare the coronal transient wave phenomenon discovered by SOHO extreme ultraviolet observations ("'EIT waves") wi-th the associated radio signature of a coronal shock wave (type II burst). 90% of the type II bursts are associated with an EIT wave. On average, the speed derived from the radio burst is about three times larger than the EIT wave speed. Within the sample, there is no correlation between the speeds of both tracers of a coronal disturbance, Under very general assumptions we conclude that both wave phenomena can be different signatures of the same fast magnetosonic disturbance. C1 Astrophys Inst Potsdam, D-14482 Potsdam, Germany. NASA, Goddard Space Flight Ctr, Space Applicat Corp, Greenbelt, MD 20771 USA. RP Klassen, A (reprint author), Astrophys Inst Potsdam, An Sternwarte 16, D-14482 Potsdam, Germany. RI Thompson, Barbara/C-9429-2012 NR 29 TC 171 Z9 175 U1 1 U2 1 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD FEB PY 2000 VL 141 IS 3 BP 357 EP 369 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287VP UT WOS:000085527400001 ER PT J AU Bloom, SD Hallum, J Terasranta, H Tornikoski, M AF Bloom, SD Hallum, J Terasranta, H Tornikoski, M TI Radio and millimeter spectral properties of newly identified high-energy gamma-ray sources SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects : individual (GB 105536.5+564424); gamma rays : observations; radio continuum : galaxies ID BL LAC OBJECTS; ACTIVE GALAXIES; EGRET SOURCES; BLAZARS; EMISSION; FLARE; IDENTIFICATIONS; MARKARIAN-421; POLARIZATION; OUTBURSTS AB We have conducted a variability study of several radio/millimeter sources that are possible counterparts of high-energy gamma-ray sources detected by EGRET. Some sources were possibly variable during this period. The radio source with the highest spectral and temporal coverage, PMN J0850-1213, behaves in a manner consistent with the shocked-jet models for extragalactic radio sources proposed in the literature. In addition, GB 105536.5 + 564424 is an X-ray-selected BL Lac object, and, if the identification with the EGRET source is correct, it would be the most distant such object detected at energies > 100 MeV (z = 0.41). A future detection in the TeV range, as well, could provide an important constraint on absorption of very high energy gamma rays by the intergalactic infrared photon held. We also discuss the possibility that this object is a gravitationally microlensed active galactic nucleus, with the foreground lensing object at z = 0.144. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Boston Univ, Dept Astron, Boston, MA 02215 USA. Metsahovi Radio Observ, FIN-02540 Kylmala, Finland. RP Bloom, SD (reprint author), Hampden Sydney Coll, Dept Phys & Astron, Box 821, Hampden Sydney, VA 23943 USA. NR 32 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP 675 EP 681 DI 10.1086/308287 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UL UT WOS:000085524800006 ER PT J AU Gibson, BK Stetson, PB Freedman, WL Mould, JR Kennicutt, RC Huchra, JP Sakai, S Graham, JA Fassett, CI Kelson, DD Ferrarese, L Hughes, SMG Illingworth, GD Macri, LM Madore, BF Sebo, KM Silbermann, NA AF Gibson, BK Stetson, PB Freedman, WL Mould, JR Kennicutt, RC Huchra, JP Sakai, S Graham, JA Fassett, CI Kelson, DD Ferrarese, L Hughes, SMG Illingworth, GD Macri, LM Madore, BF Sebo, KM Silbermann, NA TI The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XXV. A recalibration of cepheid distances to Type Ia supernovae and the value of the hubble constant SO ASTROPHYSICAL JOURNAL LA English DT Article DE Cepheids; distance scale; galaxies : distances and redshifts; supernovae : general ID ABSOLUTE PEAK BRIGHTNESS; METALLICITY DEPENDENCE; CALIBRATION; PHOTOMETRY; PARAMETERS; DISCOVERY; VARIABLES; NGC-5253; GALAXIES; IC-4182 AB Cepheid-based distances to seven Type Ia supernovae (SNe) host galaxies have been derived using the standard Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale pipeline. For the first time, this allows for a transparent comparison of data accumulated as part of three different HST projects: the Key Project, the Sandage et al. Type Ia supernovae (SNe) program, and the Tanvir et al. Leo I Group study. Reanalyzing the Tanvir et al. galaxy and six Sandage et al. galaxies, we find a mean (weighted) offset in true distance moduli of 0.12 +/- 0.07 mag; i.e., 6% in linear distance, in the sense of reducing the distance scale or increasing H-0. Adopting the reddening-corrected Hubble relations of Suntzeff et al. tied to a zero point based on SNe 1990N, 1981B, 1998bu, 1989B, 1972E, and 1960F and the photometric calibration of Hill et al. leads to a Hubble constant of H-0 = 68 +/- 2(random) +/- 5(systematic) km s(-1) Mpc(-1). Adopting the Kennicutt et al. Cepheid period-luminosity-metallicity dependency decreases the inferred H-0 by 4%. The H-0 result from Type Ia SNe is now in good agreement, to within their respective uncertainties, with that from the Tully-Fisher and surface brightness fluctuation relations. C1 Univ Colorado, Dept Astrophys & Planetary Sci, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Harvard Univ, Ctr Astrophys, Cambridge, MA 02138 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Williams Coll, Dept Astron, Williamstown, MA 01267 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95064 USA. CALTECH, Jet Prop Lab, Infrared Proc & Anal Ctr, Pasadena, CA 91125 USA. RP Gibson, BK (reprint author), Univ Colorado, Dept Astrophys & Planetary Sci, Ctr Astrophys & Space Astron, Campus Box 389, Boulder, CO 80309 USA. RI Gibson, Brad/M-3592-2015; OI Gibson, Brad/0000-0003-4446-3130; Fassett, Caleb/0000-0001-9155-3804 NR 54 TC 130 Z9 131 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP 723 EP 744 DI 10.1086/308306 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UL UT WOS:000085524800010 ER PT J AU Ferrarese, L Mould, JR Kennicutt, RC Huchra, J Ford, HC Freedman, WL Stetson, PB Madore, BF Sakai, S Gibson, BK Graham, JA Hughes, SM Illingworth, GD Kelson, DD Macri, L Sebo, K Silbermann, NA AF Ferrarese, L Mould, JR Kennicutt, RC Huchra, J Ford, HC Freedman, WL Stetson, PB Madore, BF Sakai, S Gibson, BK Graham, JA Hughes, SM Illingworth, GD Kelson, DD Macri, L Sebo, K Silbermann, NA TI The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XXVI. The calibration of population II secondary distance indicators and the value of the hubble constant SO ASTROPHYSICAL JOURNAL LA English DT Article DE Cepheids; distance scale; galaxies : star clusters; stars : late-type ID RED-GIANT-BRANCH; SURFACE BRIGHTNESS FLUCTUATIONS; NEBULA LUMINOSITY FUNCTION; GLOBULAR-CLUSTER SYSTEM; PLANETARY-NEBULAE; STANDARD CANDLES; VIRGO CLUSTER; INFRARED PHOTOMETRY; ELLIPTIC GALAXIES; COMA CLUSTER AB A Cepheid-based calibration is derived for four distance indicators that utilize stars in old stellar populations: the tip of the red giant branch (TRGB), the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), and the surface brightness fluctuation method (SBF). The calibration is largely based on the Cepheid distances to 18 spiral galaxies within ct = 1500 km s(-1) obtained as part of the Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale, but relies also on Cepheid distances from separate HST and ground-based efforts. The newly derived calibration of the SBF method is applied to obtain distances to four Abell clusters in the velocity range 3800-5000 km s(-1). Combined with cluster velocities corrected for a cosmological flow model, these distances imply a value of the Hubble constant of H-0 = 69 +/- 4 (random) +/- 6 (systematic) km s(-1) Mpc(-1). This result assumes that the Cepheid PL relation is independent of the metallicity of the variable stars; adopting a metallicity correction as in Kennicutt et al. would produce a 5% +/- 3% decrease in H-0. Finally, the newly derived calibration allows us to investigate systematics in the Cepheid, PNLF, SBF, GCLF, and TRGB distance scales. C1 CALTECH, Pasadena, CA 91125 USA. Australian Natl Univ, Inst Adv Studies, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Johns Hopkins Univ, Baltimore, MD 21218 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Carnegie Observ, Pasadena, CA 91101 USA. Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. NASA, IPAC Extragalact Database, Pasadena, CA 91125 USA. CALTECH, Pasadena, CA 91125 USA. Natl Opt Astron Observ, Kitt Peak Natl Observ, Tucson, AZ 85726 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Royal Greenwich Observ, Cambridge CB3 0HA, England. Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95064 USA. RP Ferrarese, L (reprint author), CALTECH, Pasadena, CA 91125 USA. RI Gibson, Brad/M-3592-2015 OI Gibson, Brad/0000-0003-4446-3130 NR 99 TC 172 Z9 173 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP 745 EP 767 DI 10.1086/308309 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UL UT WOS:000085524800011 ER PT J AU Mould, JR Huchra, JP Freedman, WL Kennicutt, RC Ferrarese, L Ford, HC Gibson, BK Graham, JA Hughes, SMG Illingworth, GD Kelson, DD Macri, LM Madore, BF Sakai, S Sebo, KM Silbermann, NA Stetson, PB AF Mould, JR Huchra, JP Freedman, WL Kennicutt, RC Ferrarese, L Ford, HC Gibson, BK Graham, JA Hughes, SMG Illingworth, GD Kelson, DD Macri, LM Madore, BF Sakai, S Sebo, KM Silbermann, NA Stetson, PB TI The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XXVIII. Combining the constraints on the hubble constant SO ASTROPHYSICAL JOURNAL LA English DT Article DE Cepheids; cosmology : observations; distance scale; galaxies : distances and redshifts ID PECULIAR VELOCITY-FIELD; LOCAL SUPERCLUSTER; CEPHEID DISTANCE; ELLIPTICAL GALAXIES; EXPANSION RATE; IA SUPERNOVAE; UNIVERSE; DENSITY; MOTIONS; CLUSTER AB Since the launch of Hubble Space Telescope (HST) 9 yr ago, Cepheid distances to 25 galaxies have been determined for the purpose of calibrating secondary distance indicators. Eighteen of these have been measured by the HST Key Project team, sir; by the Supernova Calibration Project, and one independently by Tanvir. Collectively, this work; sets out an array of survey markers over the region within 25 Mpc of the Milky Way. A variety of secondary distance indicators can now be calibrated, and the accompanying four papers employ the full set of 25 galaxies to consider the Tully-Fisher relation, the fundamental plane of elliptical galaxies, Type Ia supernovae, and surface brightness fluctuations. When calibrated with Cepheid distances, each of these methods yields a measurement of the Hubble constant and a corresponding measurement uncertainty. We combine these measurements in this paper, together with a model of the velocity held, to yield the best available estimate of the value of H-0 within the range of these secondary distance indicators and its uncertainty. The uncertainty in the result is modeled in an extensive simulation we call the "virtual Key Project." The velocity-held model includes the influence of the Virgo cluster, the Great Attractor, and the Shapley supercluster, but does not play a significant part in determining the result. The result is H-0 = 71 +/- 6 km s(-1) Mpc(-1). The largest contributor to the uncertainty of this 67% confidence level result is the distance of the Large Magellanic Cloud, which has been assumed to be 50 +/- 3 kpc. This takes up the first 6.5% of our 9% error budget. Other contributors are the photometric calibration of the WFPC2 instrument, which takes up 4.5%, deviations from uniform Hubble flow in the volume sampled (less than or similar to 2%), the composition sensitivity of the Cepheid period-luminosity relation (4%), and departures from a universal reddening law (similar to 1%). These are the major components that, when combined in quadrature, make up the 9% total uncertainty. If the LMC distance modulus were systematically smaller by 1 sigma than that adopted here, the derived value of the Hubble constant would increase by 4 km s(-1) Mpc(-1). Most of the significant systematic errors are capable of amelioration in future work. These include the uncertainty in the photometric calibration of WFPC2, the LMC distance, and the reddening correction. A NICMOS study is in its preliminary reduction phase, addressing the last of these concerns. Various empirical analyses have suggested that Cepheid distance moduli are affected by metallicity differences. If we adopted the composition sensitivity obtained in the Key Project's study of M101, and employed the oxygen abundances measured spectroscopically in each of the Cepheid fields we have studied, the value of the Hubble constant would be reduced by 4% +/- 2% to 68 +/- 6 km s(-1) Mpc(-1). C1 Australian Natl Univ, Mt Stromlo Observ, Inst Adv Studies, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Colorado, CASA, Boulder, CO 80309 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Royal Greenwich Observ, Cambridge CB3 0EZ, England. Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95064 USA. CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. RP Mould, JR (reprint author), Australian Natl Univ, Mt Stromlo Observ, Inst Adv Studies, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia. RI Gibson, Brad/M-3592-2015 OI Gibson, Brad/0000-0003-4446-3130 NR 51 TC 358 Z9 359 U1 2 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP 786 EP 794 DI 10.1086/308304 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UL UT WOS:000085524800013 ER PT J AU Shuping, RY Snow, TP Chiar, JE Kerr, T AF Shuping, RY Snow, TP Chiar, JE Kerr, T TI Solid-state CO toward rho Ophiuchi Elias 25: Ice thresholds revisited SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM : lines and bands; ISM : abundances; ISM : clouds; ISM : individual (Ophiuchus Cloud); ISM : molecules ID TAURUS DARK CLOUDS; INFRARED-SPECTROSCOPY; MOLECULAR CLOUD; CARBON-MONOXIDE; FORMING REGIONS; DESORPTION; EVOLUTION; CLUSTER; CORES; DUST AB In this paper we report the detection of CO ice at 4.67 mu m toward Elias 25 in the rho Ophiuchi cloud. The data were obtained using the UKIRT CGS4, and the CO-ice band is among the weakest yet observed. We compare our result to previous CO and H(2)O ice detections in an effort to understand the extinction thresholds for ice growth (A(th)). Our data imply A(th) < 11 magnitudes for CO ices in rho Oph, much less than previously thought. We tentatively suggest that the OB star lines of sight reflect ice growth trends for pristine molecular cloud material not associated with star formation. C1 Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Joint Astron Ctr, Hilo, HI 96720 USA. RP Shuping, RY (reprint author), Univ Colorado, Ctr Astrophys & Space Astron, Campus Box 391, Boulder, CO 80309 USA. EM shuping@casa.colorado.edu NR 30 TC 11 Z9 11 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP 932 EP 935 DI 10.1086/308324 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UL UT WOS:000085524800027 ER PT J AU Cui, W Chen, W Zhang, SN AF Cui, W Chen, W Zhang, SN TI Evidence for Doppler-shifted iron emission lines in black hole candidate 4U 1630-47 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; line : profiles; stars : individual (4U 1630-47); X-rays : stars ID X-RAY TRANSIENT; CYGNUS X-1; RXTE OBSERVATIONS; ACCRETION DISK; GRO J1655-40; 4U-1630-47; OUTBURST; SPECTRA; GRS-1915+105; ASCA AB We report the first detection of a pair of correlated emission lines in the X-ray spectrum of black hale candidate 4U 1630-47 during its 1996 outburst, based on Rossi X-Rap Timing Explorer (RXTE) observations of the source. At the peak plateau of the outburst, the emission lines are detected, centered mostly at similar to 5.7 and similar to 7.7 keV, respectively, while the line energies exhibit random variability similar to 5%. Interestingly, the lines move in a concerted manner to keep their separation roughly constant. The lines also vary greatly in strength, but with the lower energy line always much stronger than the higher energy one. The measured equivalent width ranges from similar to 50 to similar to 270 eV for the former, and from insignificant detection to similar to 140 eV for the latter; the two are reasonably correlated. The correlation between the lines implies a causal connection; perhaps they share a common origin. Both lines may arise from a single K alpha line of highly ionized iron that is Doppler shifted either in a Keplerian accretion disk or in a bipolar outflow or even both. In both scenarios, a change in the line energy might simply reflect a change in the ionization state of line-emitting matter. We discuss the implication of the results and also raise some questions about such interpretations. C1 MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Cui, W (reprint author), MIT, Ctr Space Res, Room 37-571, Cambridge, MA 02139 USA. OI Cui, Wei/0000-0002-6324-5772 NR 37 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP 952 EP 960 DI 10.1086/308314 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UL UT WOS:000085524800030 ER PT J AU Pickett, BK Cassen, P Durisen, RH Link, R AF Pickett, BK Cassen, P Durisen, RH Link, R TI The effects of thermal energetics on three-dimensional hydrodynamic instabilities in massive protostellar disks. II. High-resolution and adiabatic evolutions SO ASTROPHYSICAL JOURNAL LA English DT Article DE hydrodynamics; instabilities; planetary systems; solar system : formation; stars : formation ID SELF-GRAVITATING DISKS; ROTATING PROTOSTARS; PARTICLE HYDRODYNAMICS; POLYTROPES; CLOUDS; STAR; SIMULATIONS; MODELS; WAVES AB In this paper, the effects of thermal energetics on the evolution of gravitationally unstable protostellar disks are investigated by means of three-dimensional hydrodynamic calculations. The initial states for the simulations correspond to stars with equilibrium, self-gravitating disks that are formed early in the collapse of a uniformly rotating, singular isothermal sphere. In a previous paper (Pickett et al.), it was shown that the nonlinear development of locally isentropic disturbances can be radically different than that of locally isothermal disturbances, even though growth in the linear regime may be similar. When multiple low-order modes grew rapidly in the star and inner disk region and saturated at moderate nonlinear levels in the isentropic evolution, the same modes in the isothermal evolution led to shredding of the disk into dense arclets and ejection of material. In this paper, we (1) examine the fate of the shredded disk with calculations at higher spatial resolution than the previous simulations had and (2) follow the evolution of the same initial state using an internal energy equation rather than the assumption of locally isentropic or locally isothermal conditions. Despite the complex structure of the nonlinear features that developed in the violently unstable isothermal disk referred to above, our previous calculation produced no gravitationally independent, long-lived stellar or planetary companions. The higher resolution calculations presented here confirm this result. When the disk of this model is cooled further, prompting even more violent instabilities, the end result is qualitatively the same-a shredded disk. At least for the disks studied here, it is difficult to produce condensations of material that do not shear away into fragmented spirals. It is argued that the ultimate fate of such fragments depends on how readily local internal energy is lost. On the other hand, if a dynamically unstable disk is to survive for very long times without shredding, then some mechanism must mitigate and control any violent phenomena that do occur. The prior simulations demonstrated a marked difference in final outcome, depending upon the efficiency of disk cooling under two different, idealized thermal conditions. We have here incorporated an internal energy equation that allows for arbitrary heating and cooling. Simulations are presented for adiabatic models with and without artificial viscosity. The artificial viscosity accounts for dissipation and heating due to shocks in the code physics. The expected nonaxisymmetric instabilities occur and grow as before in these energy equation evolutions. When artificial viscosity is not present, the model protostar displays behavior between the locally isentropic and locally isothermal cases of the last paper; a strong two-armed spiral grows to nonlinear amplitudes and saturates at a level higher than in the locally isentropic case. Since the amplitude of the spiral disturbance is large, it is expected that continued transport of material and angular momentum will occur well after the end of the calculation at nearly four outer rotation periods. The spiral is not strong enough, however, to disrupt the disk as in the locally isothermal case. When artificial viscosity is present, the same disturbances reach moderate nonlinear amplitude, then heat the gas, which in turn greatly reduces their strength and effects on the disk. Additional heating in the low-density regions of the disk also leads to a gentle flow of material vertically off the computational grid. The energy equation and high-resolution isothermal calculations are used to discuss the importance and relevance of the different thermal regimes so far examined, with particular attention to applications to star and planet formation. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. Indiana Univ, Dept Astron, Bloomington, IN 47405 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. RP Pickett, BK (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 35 TC 82 Z9 82 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP 1034 EP 1053 DI 10.1086/308301 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UL UT WOS:000085524800040 ER PT J AU Jones, HP Branston, DD Jones, PB Wills-Davey, MJ AF Jones, HP Branston, DD Jones, PB Wills-Davey, MJ TI Analysis of NASA/NSO spectromagnetograph observations for comparison with solar irradiance variations SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : activity; Sun : general; Sun : magnetic fields; techniques : image processing ID MAGNETIC-FIELDS; REGIONS AB The NASA/NSO Spectromagnetograph (SPM) at the National Solar Observatory/Kitt Peak Vacuum Telescope (NSO/KPVT) has produced daily full-disk solar images of line-of-sight (LOS) magnetic flux, LOS velocity, continuum intensity, equivalent width, and central line depth in either Fe I 550.7 nm or Fe I 868.8 nm since 1992 April. Internally, these five images are strictly cospatial and cotemporal. This paper describes reduction techniques for removing spurious effects (principally from clouds and optical vignetting) from the images and presents summary statistics from the first 2 years of operation. Pairs of bivariate histograms as well as five-dimensional histograms are formed from the "cleaned" images. Factor analysis of various summary statistics from the histograms shows that mixed-polarity magnetic elements of weak to moderate strength; unipolar magnetic features, including active regions and strong enhanced network; and sunspots are the most important sources of variance in the SPM data. Multiple regressions of spacecraft measurements of bolometric solar irradiance on the dominant factors, however, yield strong correlations with only unipolar regions and sunspots; the weak and mixed-polarity features that account for most of the SPM variance are only weakly correlated with the spacecraft measurements. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Univ Arizona, Ctr Informat & Comp Technol, Tucson, AZ 85721 USA. Montana State Univ, Dept Phys, Bozeman, MT 59717 USA. RP Jones, HP (reprint author), NASA, GSFC, SW Solar Stn, NSO, POB 26732, Tucson, AZ 85726 USA. NR 18 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP 1070 EP 1083 DI 10.1086/308315 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UL UT WOS:000085524800042 ER PT J AU Auchere, F DeForest, CE Artzner, G AF Auchere, F DeForest, CE Artzner, G TI In-flight determination of the plate scale of the extreme-ultraviolet imaging telescope SO ASTROPHYSICAL JOURNAL LA English DT Article DE instrumentation : miscellaneous; Sun : fundamental parameters ID SOHO MISSION; SOLAR AB Using simultaneous observations of the Michelson Doppler Imager and Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory spacecraft, we determined in flight the plate scale of the EIT. We found a value of 2."629 +/- 0."001 pixel(-1), in fair agreement with the 2."627 +/- 0."001 pixel(-1) value deduced from recent laboratory measurements of the focal length and much higher by 7 sigma than the 2."622 pixel(-1) value of the preflight calibrations. The plate scale is found to be constant across the field of view, confirming the negligible distortion level predicted by the theoretical models of the EIT. Furthermore, the 2 sigma difference between our results and the latest laboratory measurements, although statistically small, may confirm a recent work suggesting that the solar photospheric radius may be 0.5 Mm lower than the classically adopted value of 695.99 Mm. C1 NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Univ Paris 11, CNRS, Inst Astrophys Spatiale, F-91405 Orsay, France. Stanford Univ, NASA, GSFC, Greenbelt, MD 20771 USA. RP Auchere, F (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 682-3,Bldg 26,Room G-1, Greenbelt, MD 20771 USA. NR 6 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP L115 EP L117 DI 10.1086/312471 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UN UT WOS:000085525000013 ER PT J AU Borne, KD Bushouse, H Lucas, RA Colina, L AF Borne, KD Bushouse, H Lucas, RA Colina, L TI Evidence for multiple mergers among ultraluminous infrared galaxies: Remnants of compact groups? SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : general; galaxies : interactions; galaxies : starburst; infrared : galaxies ID EVOLUTION; ORIGIN AB In a large sample of ultraluminous infrared galaxies (ULIRGs) imaged with the Hubble Space Telescope, we have identified a significant subsample that shows evidence for multiple mergers. The evidence is seen among two classes of ULIRGs: (1) those with multiple remnant nuclei in their core, sometimes accompanied by a complex system of tidal tails, and (2) those that are in fact dense groupings of interacting (soon-to-merge) galaxies. We conservatively estimate that, in the redshift range 0.05 < z < 0.20, at least 20 (out of 99) ULIRGs satisfy one or both of these criteria, We present several cases and discuss the possibility that the progenitors of ULIRGs may be the more classical, weakly interacting compact groups of galaxies (see Hickson). An evolutionary progression is consistent with the results: from compact groups to pairs to ULIRGs to elliptical galaxies. The last step follows the blowout of gas and dust from the ULIRG. C1 NASA, Goddard Space Flight Ctr, Raytheon Informat Technol & Sci Serv, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. UC, CSIC, Inst Fis Cantabria, Fac Ciencias, Santander 39005, Spain. RP Borne, KD (reprint author), NASA, Goddard Space Flight Ctr, Raytheon Informat Technol & Sci Serv, Code 631, Greenbelt, MD 20771 USA. NR 35 TC 87 Z9 87 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP L77 EP L80 DI 10.1086/312461 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UN UT WOS:000085525000004 ER PT J AU Brown, TM Bowers, CW Kimble, RA Ferguson, HC AF Brown, TM Bowers, CW Kimble, RA Ferguson, HC TI Far-ultraviolet emission from elliptical galaxies at z=0.55 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : evolution; galaxies : stellar content; ultraviolet : galaxies ID SPACE-TELESCOPE; MAPS AB The rest-frame W-to-optical flux ratio, which characterizes the "UV upturn" phenomenon, is potentially the most sensitive tracer of age in elliptical galaxies; models predict that it may change by orders of magnitude over the course of a few gigayears. In order to trace the evolution of the UV upturn as a function of redshift, we have used the far-UV camera on the Space Telescope Imaging Spectrograph to image the galaxy cluster CL 0016+16 at,z = 0.55. Our 25" x 25" field includes four bright elliptical galaxies, spectroscopically confirmed to be passively evolving cluster members. The weak UV emission from the galaxies in our image demonstrates that the UV upturn is weaker at a look-back time similar to 5.6 Gyr earlier than our own, as compared to measurements of the UV upturn in cluster E and SO galaxies at z = 0 and z = 0.375. These images are the first with sufficient depth to demonstrate the fading of the UV upturn expected at moderate redshifts. We discuss these observations and the implications for the formation history of galaxies. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Brown, TM (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. EM tbrown@pulsar.gsfc.nasa.gov; bowers@band2.gsfc.nasa.gov; kimble@ccd.gsfc.nasa.gov; ferguson@stsci.edu NR 21 TC 32 Z9 32 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP L89 EP L93 DI 10.1086/312466 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UN UT WOS:000085525000007 ER PT J AU Charnley, SB Kaufman, MJ AF Charnley, SB Kaufman, MJ TI Carbon dioxide in star-forming regions SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : molecules; molecular processes ID GAS-GRAIN PROCESSES; MOLECULAR CLOUDS; GALACTIC-CENTER; CHEMICAL-MODELS; MAGNETOHYDRODYNAMIC SHOCKS; INTERSTELLAR GRAINS; SAGITTARIUS B2; DENSE CLOUDS; HOT CORES; CHEMISTRY AB We consider the gas-phase chemistry of CO(2) molecules in active regions. We show that CO(2) molecules evaporated from dust in hot cores cannot be efficiently destroyed and an in fact copiously produced in cooler gas. When CO(2)-rich ices are sputtered in strong MHD shock waves, the increase in atomic hydrogen, due to H(2), dissociation by ion-neutral streaming, means that CO(2) can be depleted by factors of -500 from its injected abundance. We find that a critical shock speed exists at higher preshock densities below which CO(2) molecules can be efficiently sputtered but survive in the postshock gas. These calculations offer an explanation for the low gas/solid CO(2) ratios detected by the infrared Space Observatory in star-forming cores as being due to shock destruction followed by partial reformation in warm gas. The presence of high abundances of CO(2) in the strongly shocked Galactic center clouds Sgr B2 and Sgr A also find a tentative explanation in this scenario, Shock activity plays an important role in determining the chemistry of star-forming regions, and we suggest that most hot cores are in fact shocked cores. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Charnley, SB (reprint author), Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA. RI Charnley, Steven/C-9538-2012 NR 46 TC 34 Z9 34 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 1 PY 2000 VL 529 IS 2 BP L111 EP L114 DI 10.1086/312460 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 287UN UT WOS:000085525000012 ER PT J AU Massa, D Fitzpatrick, EL AF Massa, D Fitzpatrick, EL TI A recalibration of IUE NEWSIPS low-dispersion data SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE instrumentation : spectrographs methods : data analysis; techniques : photometric; ultraviolet : general ID HD-93521; STARS AB While the low-dispersion IUE New Spectroscopic Image Processing System (NEWSIPS) data products represent a significant improvement over original IUE Spectroscopic Image Processing System (SIPS) data, they still contain serious systematic effects which compromise their utility for certain applications. We show that NEWSIPS low-resolution data are internally consistent to only 10%-15% at best, with the majority of the problem due to time-dependent systematic effects. In addition, the NEWSIPS flux calibration is shown to be inconsistent by nearly 10%. We examine the origin of these problems and proceed to formulate and apply algorithms to correct them to the similar to 3% level-a factor of 5 improvement in accuracy. Because of the temporal systematics, transforming the corrected data to the IUE flux calibration becomes ambiguous. Therefore, we elect to transform the corrected data onto the Hubble Space Telescope Faint Object Spectrograph system. This system is far more self-consistent, and transforming the IUE data to it places data from both telescopes on a single system. Finally, we perform a detailed error analysis of the corrected NEWSIPS data. We demonstrate that much of the remaining 3% systematic effects in the corrected data is traceable to problems with the NEWSIPS intensity transformation function (ITF). The accuracy could probably be doubled by rederiving the ITF. C1 NASA, Goddard Space Flight Ctr, Raytheon STX, Greenbelt, MD 20771 USA. Dept Astron, Villanova, PA 19085 USA. RP Massa, D (reprint author), NASA, Goddard Space Flight Ctr, Raytheon STX, Mailstop 631-0, Greenbelt, MD 20771 USA. EM massa@xfiles.gsfc.nasa.gov; fitz@ast.vill.edu NR 11 TC 56 Z9 56 U1 1 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD FEB PY 2000 VL 126 IS 2 BP 517 EP 535 DI 10.1086/313298 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 308VA UT WOS:000086732500011 ER PT J AU Ertl, AC Dearborn, AS Weidhofer, AR Bernauer, EM Greenleaf, JE AF Ertl, AC Dearborn, AS Weidhofer, AR Bernauer, EM Greenleaf, JE TI Exercise thermoregulation in men after 1 and 24-hours of 6 degrees head-down tilt SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE humans; body temperature; plasma volume; skin blood velocity; sweating ID PLASMA-VOLUME CHANGES; BED REST; BLOOD-VOLUME; HUMANS; STRESS; FLOW AB Background: Exercise thermoregulation is dependent on heat loss by increased skin blood flow (convective and conductive heat loss) and through enhanced sweating (evaporative heat loss). Reduction of plasma volume (PV), increased plasma osmolality, physical deconditioning, and duration of exposure to simulated and actual microgravity reduces the ability to thermoregulate during exercise. Hypothesis: We hypothesized that 24 h of head down tilt (HDT24) would alter thermoregulatory responses to a submaximal exercise test and result in a higher exercise rectal temperature (Tre) when compared with exercise Tre after 1 h of head down tilt (HDT1). Methods: Seven men [31 +/- SD 6 yr, peak oxygen uptake (VO(2)peak) Of 44 +/- 6 ml.kg(-1).min(-1)] were studied during 70 min of supine cycling at 58 +/- SE 1.5% VO(2)peak at 22.0 degrees C Tdb and 47% rh. Results: Relative to pre-tilt sitting chair rest data, HDT1 resulted in a 6.1 +/- 0.9% increase and HDT24 in a 4.3 +/- 2.3% decrease in PV (Delta = 10.4% between experiments, p < 0.05) while plasma osmolality remained unchanged (NS). Pre-exercise Tre was elevated after HDT24 (36.71 degrees C +/- 0.06 HDT1 vs. 36.93 degrees C +/- 0.11 HDT24, p < 0.05). The 70 min of exercise did not alter this relationship (p < 0.05) with respective end exercise increases in Tre to 38.01 degrees C and 38.26 degrees C [Delta = 1.30 degrees C (HDT1) and 1.33 degrees C (HDT24)]. While there were no pre-exercise differences in mean skin temperature ((T) over bar sk), a significant (p < 0.05) time X treatment interaction occurred during exercise: after min 30 in HDT24 the (T) over bar sk leveled off at 31.1 degrees C, while it continued to increase reaching 31.5 degrees C at min 70 in HDT1. A similar response (NS) occurred in skin blood veracity. Neither local sweating rates nor changes in body weight during exercise of -1.63 +/- 0.24 kg (HDT1) or -1.33 +/- 0.09 kg (HDT24) were different (NS) between experiments. Conclusion: While HDT24 resulted in elevated pre-exercise Tre, reduced PV, attenuation of Tsk and skin blood velocity during exercise, the absolute increase in exercise Tre was not altered. But if sweat rate and cutaneous vascular responses were similar at different core temperatures (unchanged thermoregulation), the Tre offset could have been caused by the HDT-induced hypovolemia. C1 NASA, Ames Res Ctr, Gravitat Res Branch 221A 2, Moffett Field, CA 94035 USA. Vanderbilt Univ, Med Ctr, Nashville, TN USA. RP Greenleaf, JE (reprint author), NASA, Ames Res Ctr, Gravitat Res Branch 221A 2, Moffett Field, CA 94035 USA. NR 24 TC 6 Z9 7 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD FEB PY 2000 VL 71 IS 2 BP 150 EP 155 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 278LU UT WOS:000084991900010 PM 10685589 ER PT J AU Byrd, KB Parker, VT Vogler, DR Cullings, KW AF Byrd, KB Parker, VT Vogler, DR Cullings, KW TI The influence of clear-cutting on ectomycorrhizal fungus diversity in a lodgepole pine (Pinus contorta) stand, Yellowstone National Park, Wyoming, and Gallatin National Forest, Montana SO CANADIAN JOURNAL OF BOTANY-REVUE CANADIENNE DE BOTANIQUE LA English DT Article DE ectomycorrhizae; community structure; clear-cutting; molecular techniques ID SEQUENCE DATABASE; MICROBIAL BIOMASS; SOIL FUNGAL; IDENTIFICATION; MYCORRHIZAE; MURICATA; SWEDEN AB Effects of clear-cutting on the ectomycorrhizal (EM) fungus community in a Pinus contorta Dougl. ex Loud. forest near Yellowstone National Park, Wyoming, U.S.A., were assessed using molecular techniques. Samples were taken by soil core in both undisturbed and clear-cut sites by randomized block design. Species overlap was compared between clear-cut and undisturbed sites and ascomycete-basidiomycete ratio was determined, using PCR-RFLP methods. Fifty species of EM fungi were detected in the clear-cut sites, the most common being Cenococcum geophilum Fr., Suillus sp., a member of the suilloid group, a Russulaceae species, and a Thelephoraceae species. Sixty-six species were detected in the undisturbed sites, which were dominated by a Suilloid species, a Tricholomataceae species, Cortinarius sp., and Cenococcum geophilum. Species composition in the clear-cut sites differed significantly from that in the undisturbed sites (P = 0.0001). However, 9 of the 14 species most commonly found in the clear-cut sites were also found in the undisturbed sites, but in much lower abundance, while species rank curves of both stand types mirrored each other. There were no significant differences in species richness, root-tip abundance, or ascomycete-basidiomycete ratio between the clear-cut and undisturbed sites. However, species richness was lower in the clear-cut sites than in the undisturbed sites. An overall loss of species richness after clear-cutting and significant changes in species composition indicate that clear-cutting can negatively alter the EM fungal community, and this may have profound effects on ecosystem function. C1 San Francisco State Univ, Dept Biol, San Francisco, CA 94132 USA. Search Extra Terr Intelligence Inst, Mt View, CA 94043 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Byrd, KB (reprint author), URS Greiner Woodward Clyde, 500 12th St,Suite 200, Oakland, CA 94607 USA. NR 19 TC 50 Z9 53 U1 5 U2 19 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA, ONTARIO K1A 0R6, CANADA SN 0008-4026 J9 CAN J BOT JI Can. J. Bot.-Rev. Can. Bot. PD FEB PY 2000 VL 78 IS 2 BP 149 EP 156 PG 8 WC Plant Sciences SC Plant Sciences GA 300ZB UT WOS:000086282700002 ER PT J AU Hergenrother, PM AF Hergenrother, PM TI Materials speed airplanes SO CHEMICAL INNOVATION LA English DT Article ID POLYIMIDES C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hergenrother, PM (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 25 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1527-4799 J9 CHEM INNOV JI Chem. Innov. PD FEB PY 2000 VL 30 IS 2 BP 35 EP 44 PG 10 WC Chemistry, Applied SC Chemistry GA 296LG UT WOS:000086025400007 ER PT J AU Noor, AK Malik, M AF Noor, AK Malik, M TI An assessment of five modeling approaches for thermo-mechanical stress analysis of laminated composite panels SO COMPUTATIONAL MECHANICS LA English DT Article ID HIGHER-ORDER THEORY; TRANSVERSE-SHEAR STRESSES; DIFFERENTIAL QUADRATURE; DEFORMATION-THEORY; FREE-VIBRATION; PLATE-THEORY; SHELLS; PREDICTION; EQUATIONS; LOAD AB A study is made of the effects of variation in the lamination and geometric parameters, and boundary conditions of multi-layered composite panels on the accuracy of the detailed response characteristics obtained by five different modeling approaches. The modeling approaches considered include four two-dimensional models, each with five parameters to characterize the deformation in the thickness direction, and a predictor-corrector approach with twelve displacement parameters. The two-dimensional models are first-order shear deformation theory, third-order theory; a theory based on trigonometric variation of the transverse shear stresses through the thickness, and a discrete layer theory. The combination of the following four key elements distinguishes the present study from previous studies reported in the literature: (1) the standard of comparison is taken to be the solutions obtained by using three-dimensional continuum models for each of the individual layers; (2) both mechanical and thermal loadings are considered; (3) boundary conditions other than simply supported edges are considered; and (4) quantities compared include detailed through-the-thickness distributions of transverse shear and transverse normal stresses. Based on the numerical studies conducted, the predictor-corrector approach appears to be the most effective technique for obtaining accurate transverse stresses, and for thermal loading, none of the two-dimensional models is adequate for calculating transverse normal stresses, even when used in conjunction with three-dimensional equilibrium equations. C1 Univ Virginia, Ctr Adv Computat Technol, NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Noor, AK (reprint author), Univ Virginia, Ctr Adv Computat Technol, NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 41 TC 46 Z9 51 U1 1 U2 3 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0178-7675 J9 COMPUT MECH JI Comput. Mech. PD FEB PY 2000 VL 25 IS 1 BP 43 EP 58 DI 10.1007/s004660050014 PG 16 WC Mathematics, Interdisciplinary Applications; Mechanics SC Mathematics; Mechanics GA 302RQ UT WOS:000086379800005 ER PT J AU Noor, AK Venneri, SL Paul, DB Hopkins, MA AF Noor, AK Venneri, SL Paul, DB Hopkins, MA TI Structures technology for future aerospace systems SO COMPUTERS & STRUCTURES LA English DT Article DE structures technology; aerospace systems; smart materials and structures; multifunctional structures; composite structures; extreme environments; load-bearing systems; computational methods ID POLYMER COMPOSITES; DESIGN AB An overview of structures technology for future aerospace systems is given. Discussion focuses on developments in component technologies that will improve the vehicle performance, advance the technology exploitation process, and reduce system life-cycle costs. The component technologies described are smart materials and structures, multifunctional materials and structures, affordable composite structures, extreme environment structures, flexible load bearing structures, and computational methods and simulation-based design. The trends in each of the component technologies are discussed and the applicability of these technologies to future aerospace vehicles is described. Published by Elsevier Science Ltd. C1 Univ Virginia, Ctr Adv Computat Technol, NASA, Langley Res Ctr, Hampton, VA 23681 USA. NASA Headquarters, Washington, DC 20546 USA. USAF, Res Lab, Wright Patterson AFB, OH 45433 USA. Boeing Phantom Works, St Louis, MO 63166 USA. RP Univ Virginia, Ctr Adv Computat Technol, NASA, Langley Res Ctr, Hampton, VA 23681 USA. EM a.k.noor@larc.nasa.gov NR 39 TC 51 Z9 57 U1 1 U2 11 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7949 EI 1879-2243 J9 COMPUT STRUCT JI Comput. Struct. PD FEB PY 2000 VL 74 IS 5 BP 507 EP 519 DI 10.1016/S0045-7949(99)00067-X PG 13 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA 276FM UT WOS:000084865000001 ER PT J AU Heber, G Biswas, R Gao, GR AF Heber, G Biswas, R Gao, GR TI Self-avoiding walks over adaptive unstructured grids SO CONCURRENCY-PRACTICE AND EXPERIENCE LA English DT Article ID CODES AB In this paper, we present self-avoiding walks as a novel technique to 'linearize' an unstructured mesh, Unlike space-filling curves which are based on a geometric embedding, our strategy is combinatorial since it uses the mesh connectivity only, We formulate a linear time-complexity algorithm for the construction of these self-avoiding walks over a triangular mesh. We also show how the concept can be easily modified for adaptive grids that are generated in a hierarchical manner based on a set of simple rules, and made amenable for Efficient parallelization. We suggest a metric that might be used to evaluate the quality of such walks and present some sample results, The proposed locality-enhancing approach should be very useful in the runtime partitioning and load balancing of adaptive unstructured grids. Copyright (C) 2000 John Wiley & Sons, Ltd. C1 NASA, Ames Res Ctr, MRJ Technol Solut, Moffett Field, CA 94035 USA. Cornell Univ, Cornell Theory Ctr, Ithaca, NY 14853 USA. Univ Delaware, CAPSL, Newark, DE 19716 USA. RP Biswas, R (reprint author), NASA, Ames Res Ctr, MRJ Technol Solut, MS T27A-1, Moffett Field, CA 94035 USA. NR 32 TC 12 Z9 12 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 1040-3108 J9 CONCURRENCY-PRACT EX JI Concurrency-Pract. Exp. PD FEB-MAR PY 2000 VL 12 IS 2-3 BP 85 EP 109 DI 10.1002/(SICI)1096-9128(200002/03)12:2/3<85::AID-CPE471>3.0.CO;2-8 PG 25 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA 318RH UT WOS:000087297300004 ER PT J AU Conkright, ME Gregg, WW Levitus, S AF Conkright, ME Gregg, WW Levitus, S TI Seasonal cycle of phosphate in the open ocean SO DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS LA English DT Article ID CENTRAL NORTH PACIFIC; ZONE COLOR SCANNER; CARIBBEAN SEA; ARABIAN SEA; PHYTOPLANKTON; ECOSYSTEM; POLLUTION; PIGMENT; WATER; HEAT AB The seasonal cycle of phosphate in the world ocean is described using all historical data lover 170,000 profiles) held at the U.S. National Oceanographic: Data Center and World Data Center-A for Oceanography. Generally, phosphate concentrations are depressed in the season of highest primary production, in conformance with phosphate's role as a major nutrient. Mean phosphate concentration in the North Pacific are twice those in the North Atlantic. The largest seasonal differences occur in the sub-polar North Atlantic and Pacific, where changes in concentration are as large as a factor of two. Temperate and equatorial regions exhibit less seasonal variability. High latitudes, upwelling areas, and river mouths exhibit a notable seasonal signal in phosphate. Enrichment of phosphate from the Amazon and Orinoco rivers appears to dominate the seasonal signal in the tropical Atlantic. In fact, the extent of the rivers' effects extend so far north into the North Atlantic gyre that it obscures the normal pattern of summer depletion occurring elsewhere in the basin. The seasonal signal in the tropical Pacific Ocean is a function of seasonal variability in the winds, which affect the strength of coastal upwelling. Published by Elsevier Science Ltd. C1 NOAA, Natl Oceanog Data Ctr, Ocean Climate Lab E OC5, Silver Spring, MD 20910 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Conkright, ME (reprint author), NOAA, Natl Oceanog Data Ctr, Ocean Climate Lab E OC5, 1315 E West Highway, Silver Spring, MD 20910 USA. NR 53 TC 23 Z9 23 U1 1 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0967-0637 J9 DEEP-SEA RES PT I JI Deep-Sea Res. Part I-Oceanogr. Res. Pap. PD FEB PY 2000 VL 47 IS 2 BP 159 EP 175 DI 10.1016/S0967-0637(99)00042-4 PG 17 WC Oceanography SC Oceanography GA 265TR UT WOS:000084262300001 ER PT J AU Herwitz, SR Slye, RE Turton, SM AF Herwitz, SR Slye, RE Turton, SM TI Long-term survivorship and crown area dynamics of tropical rain forest canopy trees SO ECOLOGY LA English DT Article DE aerial stereoparis; canopy trees; crown dynamics; crown position; direct-beam interception; lateral shading; mortality; survivorship; 3-D model; tropical rain forest ID BROAD-LEAVED FOREST; PHOTOSYNTHETIC RESPONSES; LIGHT ENVIRONMENTS; DECIDUOUS FOREST; EMERGENT TREES; MOIST FOREST; CARBON GAIN; COSTA-RICA; GROWTH; MORTALITY AB Lateral shading of direct-beam irradiation among neighboring canopy tree crowns in a nonequatorial tropical rain forest canopy was modeled as a function of solar position using a photogrammetric database derived from large-scale color aerial stereopairs (1:1500-1:3000 scale) acquired in 1976. The interception of direct-beam irradiation by the orthogonally projected crown area of each tree was computed at hourly intervals over a full calendar year using a Parameterization model of cloud-attenuated direct-beam availability. The annual totals of intercepted direct-beam irradiation (I-b) ranged from 1.81 to 4.13 GJ.m(-2).yr(-1). Expressed as a percentage of the available incident direct-beam irradiation, these values ranged from 44% to 100%. Approximately 20% of the sample population intercepted <70% of the available annual direct-beam irradiation. The long-term effects of lateral shading and the intertree differences in I-b were assessed using repeat aerial stereophotography of the same section of forest 18 yr later in 1994 for the determination of the mortality, survivorship, and crown growth of the canopy trees delimited in the 1976 stereopairs. Mortality over the 18-yr period amounted to 27.2%. Based on the lateral shading simulations, the mean annual I-b totals of the survivors and those that died were significantly different (P < 0.001). Approximately 40% of the survivors experienced crown area reductions. Although there was no significant difference in the I-b of survivors with crown growth and those with crown reductions, a relationship was established between I-b and the extent of crown area change. Canopy trees that intercept the most direct-beam irradiation and experience the least lateral shading have higher probabilities of survivorship and significant crown area changes that may be in the form of crown growth or crown reduction. Their laterally shaded neighbors have a lower survivorship probability, and those that survive persist in an inhibited state with limited crown area change. We conclude that the effects of lateral shading are not limited to the margins of treefall gaps and that lateral shading determined by crown position in the uneven upper canopies of nonequatorial tropical rain forests has a detectable effect on the long-term fates of neighboring canopy trees. C1 Clark Univ, Grad Sch Geog, Worcester, MA 01610 USA. NASA, Ames Res Ctr, Ecosyst Sci & Technol Branch, Moffett Field, CA 94035 USA. James Cook Univ N Queensland, Dept Trop Environm Studies & Geog, Cairns, Qld 4870, Australia. Clark Univ, Dept Biol, Worcester, MA 01610 USA. RP Clark Univ, Grad Sch Geog, Worcester, MA 01610 USA. EM sherwitz@clarku.edu RI Turton, Stephen/F-7585-2012 NR 60 TC 18 Z9 19 U1 3 U2 10 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0012-9658 EI 1939-9170 J9 ECOLOGY JI Ecology PD FEB PY 2000 VL 81 IS 2 BP 585 EP 597 DI 10.1890/0012-9658(2000)081[0585:LTSACA]2.0.CO;2 PG 13 WC Ecology SC Environmental Sciences & Ecology GA 279ZM UT WOS:000085077200024 ER PT J AU Nealson, K AF Nealson, K TI The future of geobiology SO ENVIRONMENTAL MICROBIOLOGY LA English DT Editorial Material C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Nealson, K (reprint author), Jet Prop Lab, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 5 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 1462-2912 J9 ENVIRON MICROBIOL JI Environ. Microbiol. PD FEB PY 2000 VL 2 IS 1 BP 7 EP 7 PG 1 WC Microbiology SC Microbiology GA 283TX UT WOS:000085292900007 ER PT J AU Wernet, MP AF Wernet, MP TI Development of digital particle imaging velocimetry for use in turbomachinery SO EXPERIMENTS IN FLUIDS LA English DT Article ID ROTOR; PIV AB Digital Particle Imaging Velocimetry (DPIV) is a powerful measurement technique, which can be used as an alternative or complementary approach to Laser Doppler Velocimetry (LDV) in a wide range of research applications. The instantaneous planar velocity measurements obtained with PIV make it an attractive technique for use in the study of the complex flow fields encountered in turbomachinery. The ability to acquire multiple measurement points of comparable accuracy to LDV results in reduced runtime and enables the study of both transient and steady state flow phenomena. Many of the same issues encountered in the application of LDV to rotating machinery apply in the application of PIV. Techniques for optical access, light sheet delivery, CCD camera technology and particulate seeding are discussed. Results from the successful application of the PIV technique to both the blade passage region of a transonic axial compressor and the diffuser region of a high speed centrifugal compressor are presented. Both instantaneous and time-averaged flow fields were obtained. The 95% confidence intervals for the velocity estimates were also determined. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Wernet, MP (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 32 TC 60 Z9 77 U1 1 U2 12 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD FEB PY 2000 VL 28 IS 2 BP 97 EP 115 DI 10.1007/s003480050015 PG 19 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 285UX UT WOS:000085407500001 ER PT J AU Des Marais, DJ AF Des Marais, DJ TI Introduction of John M. Hayes for the 1997 Alfred E. Treibs Award SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Biographical-Item C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Des Marais, DJ (reprint author), NASA, Ames Res Ctr, Mail Stop 239-4, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD FEB PY 2000 VL 64 IS 4 BP 747 EP 748 DI 10.1016/S0016-7037(00)00326-4 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 287NA UT WOS:000085511100014 ER PT J AU Ebinger, CJ Yemane, T Harding, DJ Tesfaye, S Kelley, S Rex, DC AF Ebinger, CJ Yemane, T Harding, DJ Tesfaye, S Kelley, S Rex, DC TI Rift deflection, migration, and propagation: Linkage of the Ethiopian and Eastern rifts, Africa SO GEOLOGICAL SOCIETY OF AMERICA BULLETIN LA English DT Article ID FLOOD-BASALT PROVINCE; BASIN DEVELOPMENT; NORTHERN KENYA; RED-SEA; VOLCANISM; EVOLUTION; MAGMATISM; TURKANA; YEMEN; PLUME AB The Main Ethiopian and Eastern (Gregory) rifts, sectors of the East African rift system, overlap in a 300-km-wide system of extensional basins that is more than three times the breadth of either rift away from the zone of overlap. The oldest volcanic rocks (Eocene) and possibly the oldest rift basins (Oligocene) of the East African rift system occur in this zone of overlap, The objectives of field, remote sensing, and geochronology (K-Ar and (40)Ar/(39)Ar) studies in southwestern Ethiopia were to establish a chronology of rifting and volcanism in the zone of overlap, and to correlate stratigraphic sequences with those in the Kenya rift to the south and in the Main Ethiopian rift to the north. Field observations and cross sections show that basins are bounded by steeply dipping faults, stratal dips are <30 degrees, and that extension accommodated by the intrusion of dikes is volumetrically insignificant. Thus, the style of faulting is similar to that elsewhere in East Africa south of the Afar rift. Initial volcanism between ca, 45 and 33 Ma preceded faulting and uplift, except for reactivation of some Mesozoic rift structures near the Sudan-Ethiopia border and in northern Kenya, Extensional basins began to form in late Oligocene time in the Eastern rift, and in early Miocene time in the Main Ethiopian rift. Small degrees of extension and associated volcanism in the broadly rifted zone may have been triggered by extension in the Red Sea, as well as by lithospheric heating above a mantle plume. The anomalous breadth of the zone is a consequence of rift propagation and migration, rather than basin-and-range-style extension; both the Main Ethiopian rift and Eastern rifts have propagated along north-south lines, and the Eastern rift has migrated similar to 200 km eastward since late Oligocene time, The distribution of seismicity and Quaternary volcanism suggest that the Eastern and Main Ethiopian rifts are currently linked across a 200-km-wide zone between the Omo and Segen basins. C1 Univ London Royal Holloway & Bedford New Coll, Dept Geol, Egham TW20 0EX, Surrey, England. Ethiopian Inst Geol Surveys, Addis Ababa, Ethiopia. Open Univ, Dept Earth Sci, Milton Keynes MK7 6AA, Bucks, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Colorado, Dept Geol Sci, Boulder, CO 80305 USA. Univ Leeds, Dept Earth Sci, Leeds LS2 9JT, W Yorkshire, England. RP Ebinger, CJ (reprint author), Univ London Royal Holloway & Bedford New Coll, Dept Geol, Egham TW20 0EX, Surrey, England. EM c.ebinger@gl.rhbnc.ac.uk RI Kelley, Simon/C-5489-2012 OI Kelley, Simon/0000-0002-1756-0480 NR 51 TC 107 Z9 107 U1 2 U2 26 PU GEOLOGICAL SOC AMER, INC PI BOULDER PA PO BOX 9140, BOULDER, CO 80301-9140 USA SN 0016-7606 J9 GEOL SOC AM BULL JI Geol. Soc. Am. Bull. PD FEB PY 2000 VL 112 IS 2 BP 163 EP 176 DI 10.1130/0016-7606(2000)112<0163:RDMAPL>2.3.CO;2 PG 14 WC Geosciences, Multidisciplinary SC Geology GA 281EC UT WOS:000085144100001 ER PT J AU Reiner, MJ Kaiser, ML Desch, MD AF Reiner, MJ Kaiser, ML Desch, MD TI Long-term behavior of Jovian bKOM and nKOM radio emissions observed during the Ulysses-Jupiter encounter SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND CONTROL AB We present observational evidence that the longterm behavior of Jovian bKOM and nKOM radio emissions observed during the Ulysses-Jupiter encounter was controlled by the sector structure of the solar wind. Specifically, we found brightenings in the Jovian bKOM emission, followed by a sudden cessation of the bKOM emission and an onset of an nKOM "event" that lasted for some 120 hours. This sequence of events was observed to recur every similar to 12 or 25 days from October, 1991 to mid-January, 1992 when UIysses was inbound toward Jupiter and at Jovian latitudes <2.3 degrees. These observations indicate that the solar wind structures, which influence the dynamics of Jupiter's magnetosphere, in turn control the radio emissions generated inside the magnetosphere. C1 Raytheon ITSS, Lanham, MD 20706 USA. NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Reiner, MJ (reprint author), Raytheon ITSS, 4400 Forbes Blvd, Lanham, MD 20706 USA. NR 16 TC 15 Z9 15 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 2000 VL 27 IS 3 BP 297 EP 300 DI 10.1029/1999GL003710 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 282EY UT WOS:000085204900001 ER PT J AU Wang, Y Liu, SC Anderson, BE Kondo, Y Gregory, GL Sachse, GW Vay, SA Blake, R Singh, HB Thompson, AM AF Wang, Y Liu, SC Anderson, BE Kondo, Y Gregory, GL Sachse, GW Vay, SA Blake, R Singh, HB Thompson, AM TI Evidence of convection as a major source of condensation nuclei in the northern midlatitude upper troposphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AEROSOL-PARTICLES; EMISSION INDEXES; AIRCRAFT; PLUMES; CHEMISTRY; NO AB We examine concurrent measurements of CN (size >8 nm), NO, and NOy in the upper troposphere over the North Atlantic during the SONEX Experiment (Oct.-Nov., 1997). High CN and NOy observations are attributed largely to the enhancement in convective outflow. Using the ratio of NO/NOy as a chemical clock, we estimate that dilution of convective high-CN plumes is rapid (on a time scale of <2 days) and accounts for a large fraction of elevated CN concentrations above the background. We estimate that less than 7% of observed high-CN (>10000 cm(-3)) plumes may be attributed to aircraft emissions. The contribution by aircraft emissions to upper tropospheric CN concentrations is estimated to be significantly higher than 7% because aircraft plumes dilute much faster than convective plumes and hence an sampled less frequently. C1 Georgia Inst Technol, Atlanta, GA 30332 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Nagoya Univ, Toyokawa, Japan. Univ Calif Irvine, Irvine, CA USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wang, Y (reprint author), Rutgers State Univ, Dept Environm Sci, 14 Coll Farm Rd, New Brunswick, NJ 08901 USA. RI Kondo, Yutaka/D-1459-2012; Wang, Yuhang/B-5578-2014; Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 25 TC 28 Z9 29 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 2000 VL 27 IS 3 BP 369 EP 372 DI 10.1029/1999GL010930 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 282EY UT WOS:000085204900019 ER PT J AU Cho, JYN Newell, RE Sachse, GW AF Cho, JYN Newell, RE Sachse, GW TI Anomalous scaling of mesoscale tropospheric humidity fluctuations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LIQUID WATER DISTRIBUTIONS; MARINE STRATOCUMULUS; INVARIANCE; AIRCRAFT; ISSUES AB Water vapor fluctuations are measured and analyzed at an unprecedented 10-m resolution throughout the troposphere. Computation of structure functions shows that specific humidity variations observed by research aircraft over the Pacific Ocean exhibit anomalous scaling from about 50 m to 100 km in horizontal range. The scaling laws show different characteristics for the marine boundary layer, the tropical free troposphere, and the extratropical free troposphere. More specifically, boundary-layer humidity fluctuations are less smooth and more stationary than those in the free troposphere, while the extratropical free tropospheric variations are less intermittent than those in the other two regions. The anomalous scaling results argue against passive advection by a spatially smooth flow (chaotic advection) at these scales. C1 MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Cho, JYN (reprint author), MIT, Dept Earth Atmospher & Planetary Sci, 77 Massachusetts Ave,54-1823, Cambridge, MA 02139 USA. NR 12 TC 24 Z9 24 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 2000 VL 27 IS 3 BP 377 EP 380 DI 10.1029/1999GL010846 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 282EY UT WOS:000085204900021 ER PT J AU Perigaud, CM Cassou, C AF Perigaud, CM Cassou, C TI Importance of oceanic decadal trends and westerly wind bursts for forecasting El Nino SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PACIFIC; TIME AB In the western Pacific, Westerly Wind Bursts (WWB) usually show up in the boreal fall-winter season, depending on the activity of the Madden and Jullian oscillation. It is demonstrated with a coupled ocean-atmosphere model that WWB have an impact on the coupled system in El Nino forecasting that depends on the ocean preconditioning. Sea level data reveal decadal changes of the Ocean Heat Content of the entire tropical Pacific (the OHC), with a minimum in the mid-1980s relative to highs before 1982 and after 1996. Adding the WWB in the forecast system does not degrade the successful predictions when the OHC is low whereas WWB are necessary in winter 1981-82 and 1996-97 to successfully predict the forthcoming warm events. Thus, when the OHC is high in addition to the other traditional conditions being favorable for a warm growth, WWB contribute to having a strong El Nino event the following year. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. CERFACS, F-31057 Toulouse, France. RP Perigaud, CM (reprint author), CALTECH, Jet Prop Lab, MS 300-323, Pasadena, CA 91009 USA. NR 12 TC 31 Z9 32 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 2000 VL 27 IS 3 BP 389 EP 392 DI 10.1029/1999GL010781 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 282EY UT WOS:000085204900024 ER PT J AU Vincent, MB Clarke, JT Ballester, GE Harris, WM West, RA Trauger, JT Evans, RW Stapelfeldt, KR Crisp, D Burrows, CJ Gallagher, JS Griffiths, RE Hester, JJ Hoessel, JG Holtzman, JA Mould, JR Scowen, PA Watson, AM Westphal, JA AF Vincent, MB Clarke, JT Ballester, GE Harris, WM West, RA Trauger, JT Evans, RW Stapelfeldt, KR Crisp, D Burrows, CJ Gallagher, JS Griffiths, RE Hester, JJ Hoessel, JG Holtzman, JA Mould, JR Scowen, PA Watson, AM Westphal, JA TI Mapping Jupiter's latitudinal bands and great red spot using HST/WFPC2 far-ultraviolet imaging SO ICARUS LA English DT Article DE Jupiter; atmosphere; ultraviolet observations; HST ID HUBBLE-SPACE-TELESCOPE; ABSOLUTE REFLECTIVITY; STRATOSPHERE; AURORA; SCATTERING; EQUATORIAL; PHOTOMETRY; FEATURES; SPECTRA; SATURN AB Jupiter's low and mid-latitudes are examined using ultraviolet (UV) images obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 over the period of 1994-1997. Effective atmospheric pressures probed by the F160W, F218W, and F255W are estimated at 100, 1.65, and 370 mbar, respectively, at low latitudes. Far-ultraviolet images of Jupiter taken with the F160W filter reveal bright and dark latitudinal bands at low and mid-latitudes. These bands were found to be correlated with the zonal winds; the bright bands are at latitudes of subsidences, and the dark bands at upwellings. The sense of this correlation is opposite to that seen in visible images of Jupiter where the bright zones are located over upwellings, and dark belts over subsidences. The locations of the dark bands seen in the F160W images are consistent with enhanced concentrations of NH(3) and/or aerosols in the upwellings near the tropopause. Anticyclonic ovals, like the Great Red Spot, are regions of upwellings, and also appear dark in the F160W images. Temporal variations were also observed in the contrast of the low-latitude bands. An increase in the contrast of the low-latitude bands appeared to coincide with a visible wavelength broadening of the North Equatorial Belt that occurred in early to mid-1996. Changes at mid-southern latitudes were observed in the aftermath of the SL-9 impacts in July 1994. (C) 2000 Academic Press. C1 Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. Univ Wisconsin, Space Astron Lab, Madison, WI 53706 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Arizona State Univ, Dept Phys & Astron, Tempe, AZ 85287 USA. New Mexico State Univ, Dept Astron, Las Cruces, NM 88003 USA. Australian Natl Univ, Mt Stromlo & Siding Spring Observ, Weston, ACT 2611, Australia. Univ Nacl Autonoma Mexico, Inst Astron, Morelia 58090, Michoacan, Mexico. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Vincent, MB (reprint author), Univ Michigan, Dept Atmospher Ocean & Space Sci, Space Res Bldg,2455 Hayward, Ann Arbor, MI 48109 USA. EM mvincent@sunshine.engin.umich.edu RI Stapelfeldt, Karl/D-2721-2012; Clarke, John/C-8644-2013 NR 51 TC 11 Z9 11 U1 2 U2 6 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 189 EP 204 DI 10.1006/icar.1999.6232 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800001 ER PT J AU Vincent, MB Clarke, JT Ballester, GE Harris, WM West, RA Trauger, JT Evans, RW Stapelfeldt, KR Crisp, D Burrows, CJ Gallagher, JS Griffiths, RE Hester, JJ Hoessel, JG Holtzman, JA Mould, JR Scowen, PA Watson, AM Westphal, JA AF Vincent, MB Clarke, JT Ballester, GE Harris, WM West, RA Trauger, JT Evans, RW Stapelfeldt, KR Crisp, D Burrows, CJ Gallagher, JS Griffiths, RE Hester, JJ Hoessel, JG Holtzman, JA Mould, JR Scowen, PA Watson, AM Westphal, JA TI Jupiter's polar regions in the ultraviolet as imaged by HST/WFPC2: Auroral-aligned features and zonal motions SO ICARUS LA English DT Article DE Jupiter; atmosphere; atmosphere dynamics; ultraviolet observations; HST ID STRATOSPHERIC AEROSOLS; COMET SHOEMAKER-LEVY-9; ATMOSPHERE; LATITUDE; PROBE; TEMPERATURE; ABUNDANCES; SATURN; IMPACT; SYSTEM AB Jupiter's polar regions are examined using ultraviolet (UV, 120-320 nm) images obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 over the period of 1994-1997, These images probe the stratospheric aerosols at pressures of a few tens of millibars. We discovered a UV-darkened segment in the polar shading just equatorward of the north polar hood that remained aligned with the southern-most portion of the north auroral oval. The darkened segment generally extended over 100 degrees-260 degrees System III longitude, and 39 degrees-53 degrees N planetocentric latitude in the F160W, F218W, and F255W images. No single type of feature in the F218W and F255W images appeared consistently aligned within the outline of the north auroral oval, but several transient features were observed. It is not certain whether these transient features were associated with auroral processes, or just coincidentally aligned. A "south dark patch" was consistently observed within the outline of the south auroral oval and was temporally variable in size and shape. By tracking selected features, we obtained the first direct measurements of the zonal motions in Jupiter's high-latitude stratosphere. Primarily retrograde motions were observed from 41 degrees N to 60 degrees N. Both prograde and retrograde motions appeared from 48 degrees S to 71 degrees S. We propose that the asymmetric appearance of the polar hoods (R. A. West 1979, Icarus 38, 12-33; R. Wagener and J. Caldwell 1988, Icarus 74, 141-152) is influenced, in part, by meridional mixing in the stratosphere. Enhanced meridional mixing would tend to be more effective at dispersing the polar aerosols to lower latitudes in the north than in the south. (C) 2000 Academic Press. C1 Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. Univ Wisconsin, Space Astron Lab, Madison, WI 53706 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Arizona State Univ, Dept Phys & Astron, Tempe, AZ 85287 USA. New Mexico State Univ, Dept Astron, Las Cruces, NM 88003 USA. Australian Natl Univ, Mt Stromlo & Siding Spring Observ, Weston, ACT 2611, Australia. Arizona State Univ, Dept Phys & Astron, Tempe, AZ 85287 USA. Univ Nacl Autonoma Mexico, Astron Inst, Morelia 58090, Michoacan, Mexico. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Vincent, MB (reprint author), Univ Michigan, Dept Atmospher Ocean & Space Sci, Space Res Bldg,2455 Hayward, Ann Arbor, MI 48109 USA. EM mvincent@sunshine.engin.umich.edu RI Stapelfeldt, Karl/D-2721-2012; Clarke, John/C-8644-2013 NR 43 TC 19 Z9 19 U1 0 U2 4 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 205 EP 222 DI 10.1006/icar.1999.6233 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800002 ER PT J AU Moses, JI Bezard, B Lellouch, E Gladstone, GR Feuchtgruber, H Allen, M AF Moses, JI Bezard, B Lellouch, E Gladstone, GR Feuchtgruber, H Allen, M TI Photochemistry of Saturn's atmosphere - I. Hydrocarbon chemistry and comparisons with ISO observations SO ICARUS LA English DT Review DE Saturn; atmosphere; photochemistry; atmospheres; composition; organic chemistry; infrared observations ID PHOTOABSORPTION CROSS-SECTIONS; RATE-CONSTANT MEASUREMENT; EVALUATED KINETIC DATA; ABSOLUTE RATE-CONSTANT; LYMAN-ALPHA-EMISSION; TEMPERATURE-DEPENDENCE; UPPER TROPOSPHERE; RATE COEFFICIENTS; HYDROGEN-ATOMS; OCCULTATION MEASUREMENTS AB To investigate the details of hydrocarbon photochemistry on Saturn, we have developed a one-dimensional diurnally averaged model that couples hydrocarbon and oxygen photochemistry, molecular and eddy diffusion, radiative transfer, and condensation. The model results are compared with observations from the Infrared Space Observatory (ISO) to place tighter constraints on molecular abundances, to better define Saturn's eddy diffusion coefficient profile, and to identify important chemical schemes that control the abundances of the observable hydrocarbons in Saturn's upper atmosphere. From the ISO observations, we determine that the column densities of CH3, CH3C2H, and C4H2 above 10 mbar are 4(-1.5)(+2) x 10(13) cm(-2), (1.1 +/- 0.3) x 10(15) cm(-2), and (1.2 +/- 0.3) x 10(14) cm(-2), respectively. The observed ISO emission features also indicate C2H2 mixing ratios of 1.2(-0.6)(+0.9) x 10(-6) at 0.3 mbar and (2.7 +/- 0.8) x 10(-7) at 1.4 mbar, and a C2H6 mixing ratio of (9 +/- 2.5) x 10(-6) at 0.5 mbar. Upper limits are provided for C2H4, CH2CCH2, C3H8, and C6H2. The sensitivity of the model results to variations in the eddy diffusion coefficient profile, the solar flux, the CH4 photolysis branching ratios, the atomic hydrogen influx, and key reaction rates are discussed in detail. We find that C4H2 and CH3C2H are particularly good tracers of important chemical processes and physical conditions in Saturn's upper atmosphere, and C2H6 is a good tracer of the eddy diffusion coefficient in Saturn's lower stratosphere. The eddy diffusion coefficient must be smaller than similar to 3 x 10(4) cm(2) s(-1) at pressures greater than 1 mbar in order to reproduce the C2H6 abundance inferred from ISO observations. The eddy diffusion coefficients in the upper stratosphere could be constrained by observations of CH3 radicals if the low-temperature chemistry of CH3 were better understood. We also discuss the implications of our modeling for aerosol formation in Saturn's lower stratosphere-diacetylene, butane, and water condense between similar to 1 and 300 mbar in our model and will dominate stratospheric haze formation at nonauroral latitudes. Our photochemical models will be useful for planning observational sequences and for analyzing data from the upcoming Cassini mission. (C) 2000 Academic Press. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. Observ Paris, DESPA, F-92195 Meudon, France. SW Res Inst, Dept Space Sci, San Antonio, TX 78228 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Moses, JI (reprint author), Lunar & Planetary Inst, 3600 Bay Area Blvd, Houston, TX 77058 USA. RI Moses, Julianne/I-2151-2013 OI Moses, Julianne/0000-0002-8837-0035 NR 172 TC 196 Z9 196 U1 3 U2 12 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 244 EP 298 DI 10.1006/icar.1999.6270 PG 55 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800004 ER PT J AU Roddier, F Roddier, C Brahic, A Dumas, C Graves, JE Northcott, MJ Owen, T AF Roddier, F Roddier, C Brahic, A Dumas, C Graves, JE Northcott, MJ Owen, T TI Adaptive optics observations of Saturn's ring plane crossing in August 1995 SO ICARUS LA English DT Article DE instrumention, adaptive optics; planetary rings; Saturn; satellites of Saturn; surfaces, satellites ID SYSTEM; SATELLITES AB Adaptive optics (0.15 " resolution) infrared images of the rings and satellites of Saturn were obtained in August 1995 as the Earth was crossing the ring plane, Twelve clumps were detected in the F ring, including HST S5 and S7 objects. For the first time H magnitudes were obtained for Prometheus, Pandora, Telesto, and Calypso, and J magnitudes for Epimetheus, Janus, Mimas, Telesto, and Helene. (C) 2000 Academic Press. C1 Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Observ Paris, F-92195 Meudon, France. Univ Paris 07, F-92195 Meudon, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Roddier, F (reprint author), Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA. NR 26 TC 11 Z9 11 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 299 EP 307 DI 10.1006/icar.1999.6251 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800005 ER PT J AU Goukenleuque, C Bezard, B Joguet, B Lellouch, E Freedman, R AF Goukenleuque, C Bezard, B Joguet, B Lellouch, E Freedman, R TI A radiative equilibrium model of 51 Peg b SO ICARUS LA English DT Article DE atmosphere, structure; atmosphere, composition; extrasolar planets ID INDUCED INFRARED-SPECTRA; GIANT PLANETS; H-2-HE PAIRS; TEMPERATURES; ABSORPTION; 7000-K; SOLAR; BAND; COMPANION; METHANE AB We present a radiative equilibrium model for extrasolar giant planets applied to 51 Peg b. The atmospheric model extends from 10(-5) to similar to 10 bar and is limited at the bottom by an optically thick cloud of silicate (Mg2SiO4 or MgSiO3) or iron (Fe) particles. Rayleigh scattering at short wavelengths and absorption by the H-2-H-2 and H-2-He continuum and molecular bands of H2O, CO, and CH4 are included. Atmospheric heating and cooling result, respectively, from absorption of stellar flux and from infrared thermal emission. The solution temperature profiles do not show any temperature inversion, in contrast with the giant planets of the solar system. The lapse rate is subadiabatic at all levels above the cloudtop, justifying the use of radiative equilibrium. We find that, under thermochemical equilibrium, CO dominates over CH4 at all levels. The effective temperature is in the range 1150-1270 K and the Bond albedo in the range 0.15-0.42, depending on the location and reflectivity of the lower cloud deck. Mg2SiO4 or Fe clouds are weakly reflective in contrast to a MgSiO3 cloud. The thermal emission spectrum prevails over the stellar reflected component below 13,000-15,000 cm(-1) (lambda > 0.7 mu m); it shows various windows, between the H2O and CO bands, with the brightest centered at 2550 cm(-1) (3.9 mu m). The most prominent CO and CH4 bands occur around 2100 (4.7 mu m) and 3030 cm(-1) (3.3 mu m). Assuming a jovian abundance for PH3, the bands around 2300 (4.3 mu m) and 2450 cm(-1) (4.1 mu m) are clearly visible in absorption at a resolving power of similar to 100. We investigated the detectability of the minor species CO and CH4 at a resolution of 4000-6000, adequate to separate the planet's absorption features from their stellar and telluric counterparts. Considering photon noise from the star as the only noise source, we find that S/N ratios of about 8 are reached on the molecular features in the 4.7- and 3.3-mu m regions after similar to 10 h of integration on an 8-m telescope. On the other hand, the planet-to-star contrast is as low as (2-4) x 10(-4). (C) 2000 Academic Press. C1 Observ Paris, Dept Rech Spatiale, F-92195 Meudon, France. NASA, Ames Res Ctr, Space Phys Res Inst, Moffett Field, CA 94035 USA. RP Goukenleuque, C (reprint author), Observ Paris, Dept Rech Spatiale, 5 Pl Jules Janssen, F-92195 Meudon, France. NR 37 TC 45 Z9 45 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 308 EP 323 DI 10.1006/icar.1999.6256 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800006 ER PT J AU Dello Russo, N Mumma, MJ DiSanti, MA Magee-Sauer, K Novak, R Rettig, TW AF Dello Russo, N Mumma, MJ DiSanti, MA Magee-Sauer, K Novak, R Rettig, TW TI Water production and release in Comet C/1995 O1 Hale-Bopp SO ICARUS LA English DT Article DE comets; Hale-Bopp; composition; infrared observations; water ID CARBON-MONOXIDE; EMISSION FEATURE; B2 HYAKUTAKE; HALLEY; CO; PHOTODISSOCIATION; SPECTROSCOPY; ATMOSPHERES; SPECTRUM; P/HALLEY AB Water (H2O) was detected in Comet C/1995 O1 Hale-Bopp on 10 dates between UT January 21.8 and May 1.2, 1997, using high-resolution infrared spectroscopy. This is the first study of the heliocentric dependence of water released from a comet using direct detection of H2O itself. Production rates and rotational temperatures were measured, and the derived heliocentric dependence for the water production rate is Q = (8.35 +/- 0.13) x 10(30) [R-h((-1.88+/-0.18))] molecules s(-1). The spatial distribution of H2O molecules in the coma is consistent with water being released directly from the nucleus within 1.5 AU of the Sun, although release of a small fraction from icy grains cannot be excluded. When our derived water production rates are compared to the production of native carbon monoxide and dust, we obtain a dust to ice mass ratio of 5.1 +/- 1.2 within a heliocentric distance of 1.5 AU. The abundance of H2O provides a benchmark for the volatile inventory in Hale-Bopp and, when compared to interstellar and nebular material, helps constrain the origin of cometary ices and their processing histories. These production rates derived from the direct detection of H2O provide a sound basis with which water production rates inferred by indirect methods can be compared. (C) 2000 Academic Press. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Rowan Univ, Dept Chem & Phys, Glassboro, NJ 08028 USA. Univ Notre Dame, Dept Phys & Astron, Notre Dame, IN 46556 USA. Iona Coll, Dept Phys, New Rochelle, NY 10801 USA. RP Dello Russo, N (reprint author), Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RI mumma, michael/I-2764-2013; Magee-Sauer, Karen/K-6061-2015; Dello Russo, Neil/G-2727-2015 OI Magee-Sauer, Karen/0000-0002-4979-9875; Dello Russo, Neil/0000-0002-8379-7304 NR 35 TC 83 Z9 83 U1 0 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 324 EP 337 DI 10.1006/icar.1999.6268 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800007 ER PT J AU Hicks, MD Buratti, BJ Newburn, RL Rabinowitz, DL AF Hicks, MD Buratti, BJ Newburn, RL Rabinowitz, DL TI Physical observations of 1996 PW and 1997 SE5: Extinct comets or D-type asteroids? SO ICARUS LA English DT Article DE asteroids; rotation; photometry; spectroscopy ID NEAR-EARTH ASTEROIDS; SPECTRA; COLORS; NUCLEI AB The minor planets 1996 PW and 1997 SE5 are two of the few known asteroids with orbital elements typical of long-period and Jupiter-family comets and as such represent strong candidates for extinct cometary nuclei. We obtained filter photometry of 1996 PW and filter photometry and medium-resolution CCD spectroscopy of 1997 SE5 during their discovery apparitions. We also observed a suite of D-type asteroids as possible spectral analogs of cometary nuclei. Both 1996 PW and 1997 SE5 have moderately red, featureless spectra typical of the D-type asteroids, cometary nuclei, and other extinct cometary candidates. The photometry for 1997 SE5 was fit by a triple-peaked lightcurve with a period of 9.050 +/- 0.005 h and an amplitude of 0.4 magnitude, suggesting a relatively complex and elongated shape. With this work, 1997 SE5 and 1996 PW join the ranks of 3552 Don Quixote and 944 Hildago as established candidates for extinct comet nuclei. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hicks, MD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 183-501, Pasadena, CA 91109 USA. NR 24 TC 14 Z9 14 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 354 EP 359 DI 10.1006/icar.1999.6258 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800010 ER PT J AU Lane, MD AF Lane, MD TI Comment on "Comparison of laboratory emission spectra with Mercury telescopic data" by A. L. Sprague and T. L. Roush SO ICARUS LA English DT Article DE spectroscopy; magnetite; Mercury, surface; infrared observations ID THERMAL EMISSION; SPECTROSCOPY; REFLECTANCE AB The magnetite spectrum in Fig, 3 of A. L. Sprague and T. L. Roush (1998, Icarus 133, 174-183) is of hematite, not magnetite, Regardless, magnetite has no diagnostic fundamental or transparency bands within the spectral range of their Mercury telescopic data; therefore, they should not conclude the absence or paucity of magnetite on Mercury on the basis of the spectral region 7.5 to 12 mu m alone. (C) 2000 Academic Press. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Lane, MD (reprint author), NASA, Lyndon B Johnson Space Ctr, Code SN3, Houston, TX 77058 USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 407 EP 408 DI 10.1006/icar.1999.6279 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800015 ER PT J AU Sprague, AL Roush, TL Downs, RT Righter, K AF Sprague, AL Roush, TL Downs, RT Righter, K TI Response to comment on "Comparison of laboratory emission spectra with Mercury telescopic data" by Melissa Lane SO ICARUS LA English DT Article AB The laboratory spectrum published in Fig. 3 of A. L. Sprague and T. L. Roush (1998, Icarus 133, 174-183) is a mixture of magnetite and hematite (similar to 34-45% magnetite, similar to 55-66% hematite) rather than magnetite or hematite (M. D. Lane 2000, Icarus 143, 000-000) alone. Because of the unusual nature of this sample (it is uniformly magnetic) we present results of X-ray diffraction, petrographic microscopy, and additional microprobe analyses. We compare this spectrum with laboratory spectra of hematite and magnetite. We can draw no conclusions regarding the presence or absence of magnetite on Mercury based solely on data in the spectral region 7.5-12 mu m. (C) 2000 Academic Press. C1 Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Ames Res Ctr, Planetary Syst Branch, Moffett Field, CA 94035 USA. Univ Arizona, Dept Geol, Tucson, AZ 85721 USA. RP Sprague, AL (reprint author), Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NR 7 TC 3 Z9 3 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 409 EP 411 DI 10.1006/icar.1999.6280 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800016 ER PT J AU Levison, HF Duncan, MJ Zahnle, K Holman, M Dones, L AF Levison, HF Duncan, MJ Zahnle, K Holman, M Dones, L TI Planetary impact rates from ecliptic comets SO ICARUS LA English DT Article ID JUPITER-FAMILY COMETS; SHORT-PERIOD COMETS; KUIPER BELT; OBJECTS; DISK AB We have reevaluated the impact rates for the planets from ecliptic comets using the integrations in H. Levison and M. Duncan (1997, Icarus 127, 13-32; LD97), We fmd that the current impact rates on the giant planets are actually about four times smaller than LD97's values due to differences in methods of calculating the relevant timescales. The newly calculated impact rates are listed in Table I. However, if the objects leaving the Kuiper belt were primarily on high inclination orbits, then the impact rates on the giant planets are larger than those in Table I by a factor less than or similar to 2. We discuss the dynamics of objects hitting the giant planets in detail, including measurements of the impact velocities. We find that 21% of the objects that hit Jupiter in our simulations were bound to the planet before the impact. The fraction of bound impactors for Saturn is much lower, Jupiter, Saturn, and Uranus have a significant apex-antapex asymmetry for the unbound impactors. (C) 2000 Academic Press. C1 SW Res Inst, Space Studies Dept, Boulder, CO 80302 USA. Queens Univ, Dept Phys, Kingston, ON K7L 3N6, Canada. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Levison, HF (reprint author), SW Res Inst, Space Studies Dept, Boulder, CO 80302 USA. RI Levison, Harold/C-6061-2013 OI Levison, Harold/0000-0001-5847-8099 NR 20 TC 57 Z9 57 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2000 VL 143 IS 2 BP 415 EP 420 DI 10.1006/icar.1999.6313 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 293JF UT WOS:000085847800018 ER PT J AU Ponchak, GE Chun, DH Yook, JG Katehi, LPB AF Ponchak, GE Chun, DH Yook, JG Katehi, LPB TI The use of metal filled via holes for improving isolation in LTCC RF and wireless multichip packages SO IEEE TRANSACTIONS ON ADVANCED PACKAGING LA English DT Article; Proceedings Paper CT 3rd international wireless communications conference (WCC 98) CY NOV 01-03, 1998 CL SAN DIEGO, CALIFORNIA DE coupling crosstalk; MCM; microstrip; microwave transmission lines; stripline ID TECHNOLOGY AB LTCC MCM's for RF and wireless systems often use metal filled via holes to improve isolation between the stripline and microstrip interconnects, In this paper, results from a 3D-FEM electromagnetic characterization of microstrip and stripline interconnects with metal filled via fences for isolation are presented, It is shown that placement of a via hole fence closer than three times the substrate height to the transmission Lines increases radiation and coupling Radiation loss and reflections are increased when a short via fence is used in areas suspected of having high radiation. Also, via posts should not be separated by more than three times the substrate height for lon radiation loss, coupling, and suppression of higher order modes in a package. C1 NASA, Glenn Res Ctr, Electron Device Technol Branch, Cleveland, OH 44135 USA. Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. Inst Sci & Technol, Dept Informat & Commun, Kwangju 500712, South Korea. RP Ponchak, GE (reprint author), NASA, Glenn Res Ctr, Electron Device Technol Branch, Cleveland, OH 44135 USA. NR 18 TC 50 Z9 53 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1521-3323 J9 IEEE TRANS ADV PACK JI IEEE Trans. Adv. Packag. PD FEB PY 2000 VL 23 IS 1 BP 88 EP 99 DI 10.1109/6040.826766 PG 12 WC Engineering, Manufacturing; Engineering, Electrical & Electronic; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 297DT UT WOS:000086067100013 ER PT J AU Siqueira, PR Sarabandi, K AF Siqueira, PR Sarabandi, K TI T-Matrix determination of effective permittivity for three-dimensional dense random media SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article DE electromagnetic propagation in random media; T-matrix method ID MONTE-CARLO SIMULATIONS; ADDITION THEOREM; EXTINCTION RATE; SCATTERING; APPROXIMATION; ALGORITHM; SPHERES AB In this paper, we present a full wave method for determining the effective permittivity for random media in three dimensions. The type of media addressed is composed of spherical dielectric particles in a homogeneous dielectric background. The particle volume fraction ranges from 0 to 40% and dielectric contrast may be significantly different from the background medium. The method described relies on the T-matrix approach for solving Maxwell's equations using a spherical wave expansion in conjunction with a Monte-Carlo simulation for calculating the mean scattered field confined within a prescribed fictitious boundary. To find the effective permittivity, the mean scattered held is compared with that of a homogeneous scatterer whose shape is defined by the fictitious boundary and its dielectric constant is varied until the scattered fields are matched. A complete description of the T-matrix approach is given along with an explanation of why the recursive form of this technique (RATMA [3]) cannot be used for addressing this problem, After the method development is completed, the results of our numerical technique are compared against the theoretical methods of the quasi-crystalline approximation and the effective field approximation to demonstrate the region of validity of the theoretical methods. The examples contained within the paper use between 30 and 120 included spheres (with radii ranging from from ka = 0.6 to 0.8) within a larger, fictitious sphere of diameter kD = 8.4. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Michigan, Ann Arbor, MI 48109 USA. RP Siqueira, PR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Siqueira, Paul/D-9760-2016 OI Siqueira, Paul/0000-0001-5781-8282 NR 20 TC 24 Z9 26 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD FEB PY 2000 VL 48 IS 2 BP 317 EP 327 DI 10.1109/8.833082 PG 11 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 304RW UT WOS:000086498800021 ER PT J AU Mundt, CW Nagle, HT AF Mundt, CW Nagle, HT TI Applications of SPICE for modeling miniaturized biomedical sensor systems SO IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING LA English DT Article DE biopotential; electrode; equivalent circuit; ion-selective; Kapton; SPICE; system model; transmission line ID CELLS; THIN AB This paper proposes a model for a miniaturized signal conditioning system for biopotential and ion-selective electrode arrays. The system consists of three main components: sensors, interconnections, and signal conditioning chip. The model for this system is based on SPICE. Transmission-line based equivalent circuits are used to represent the sensors, lumped resistance-capacitance circuits describe the interconnections, and a model for the signal conditioning chip is extracted from its layout, Conclusion: A system for measurements of biopotentials and ionic activities can be miniaturized and optimized for cardiovascular applications based on the development of an integrated SPICE system model of its electrochemical, interconnection, and electronic components. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. N Carolina State Univ, Raleigh, NC 27695 USA. RP Mundt, CW (reprint author), NASA, Ames Res Ctr, Mail Stop 213-15, Moffett Field, CA 94035 USA. NR 8 TC 3 Z9 3 U1 1 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9294 J9 IEEE T BIO-MED ENG JI IEEE Trans. Biomed. Eng. PD FEB PY 2000 VL 47 IS 2 BP 149 EP 154 DI 10.1109/10.821733 PG 6 WC Engineering, Biomedical SC Engineering GA 281YC UT WOS:000085188200002 PM 10721621 ER PT J AU Gunapala, SD Bandara, SV Liu, JK Luong, EM Stetson, N Shott, CA Bock, JJ Rafol, SB Mumolo, JM McKelvey, MJ AF Gunapala, SD Bandara, SV Liu, JK Luong, EM Stetson, N Shott, CA Bock, JJ Rafol, SB Mumolo, JM McKelvey, MJ TI Long-wavelength 256 x 256 GaAs/AlGaAs quantum well infrared photodetector (QWIP) palm-size camera SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article ID ARRAY; FABRICATION; PERFORMANCE AB A 9 mu m cutoff 256 x 256 palm-size quantum well infrared photodetector (QWIP) camera weighing only 2.5 Ibs, and using 5.5 W of power has been demonstrated. Excellent imagery, with a noise equivalent differential temperature (NE Delta T) of 23 mK has been achieved. It is well known that QWIP has very low 1/f noise, high operability, and uniformity. As a result, this camera uses a prerecorded nonuniformity correction table (i.e., gains and offsets) stored in its read-only-memory during operation, which enabled the miniaturization of this camera. In this paper, we discuss the development of this very sensitive long-wavelength infrared (LWIR) camera based on a GaAs/AlGaAs QWIP focal plane array (FPA) and its performance in terms of quantum efficiency, NE Delta T, MRDT, uniformity, and operability. C1 CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. Amber A Raytheon Co, Goleta, CA 93117 USA. Inframet Inc, Billerica, MA 01862 USA. RP Gunapala, SD (reprint author), CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. NR 14 TC 35 Z9 36 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD FEB PY 2000 VL 47 IS 2 BP 326 EP 332 DI 10.1109/16.822276 PG 7 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 284RA UT WOS:000085344800012 ER PT J AU Olson, CF AF Olson, CF TI Probabilistic self-localization for mobile robots SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article DE maximum-likelihood estimation; mobile robotics; self-localization; uncertainty estimation ID DISTANCE TRANSFORMATIONS; POSITION ESTIMATION; HAUSDORFF DISTANCE; RECOGNITION; NAVIGATION; IMAGES; RANGE; ENVIRONMENT; VISION; SONAR AB Localization is a critical issue in mobile robotics. If a robot does not know where it is, it cannot effectively plan movements, locate objects, or reach goals. In this paper, we describe probabilistic self-localization techniques for mobile robots that are based on the principle of maximum-likelihood estimation. The basic method is to compare a map generated at the current robot position with a previously generated map of the environment in order to probabilistically maximize the agreement between the maps. This method is able to operate in both indoor and outdoor environments using either discrete features or an occupancy grid to represent the world map. The map may be generated using any method to detect features in the robot's surroundings, including vision, sonar, and laser range-finder, We perform an efficient global search of the pose space that guarantees that the best position is found according to the probabilistic map agreement measure in a discretized pose space. In addition, subpixel localization and uncertainty estimation are performed by fitting the likelihood function with a parameterized surface. We describe the application of these techniques in several experiments, including experimental localization results for the Sojourner Mars rover. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM clark.olson@jpl.nasa.gov NR 59 TC 97 Z9 107 U1 3 U2 13 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD FEB PY 2000 VL 16 IS 1 BP 55 EP 66 DI 10.1109/70.833191 PG 12 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA 303MX UT WOS:000086426600007 ER PT J AU Phillips, J McIntyre, B AF Phillips, J McIntyre, B TI ENSO and interannual rainfall variability in Uganda: Implications for agricultural management SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE East Africa; Uganda; forecasts; rainfall variability; precipitation; agricultural applications ID NINO SOUTHERN OSCILLATION; SEASONAL RAINFALL; EAST-AFRICA; SHORT RAINS; PREDICTION; PATTERNS AB The El Nino-Southern Oscillation (ENSO) is correlated with the short rainy season (September-December) in East Africa. Seasonal climate forecasts made on this basis are being disseminated in the hope that this information will be useful in regional or even local planning and resource management. In order to improve the likelihood of success in using regional forecasts in Uganda, particularly in the agricultural sector, climate analysis was performed at the sub-regional level with distinctions being made between unimodal (short season peak in August) and bimodal (short season peak in November) rainfall zones. Monthly climate data from 1931 to 1960 were available for 33 sites. Averaging across all stations, it is shown that Pacific Ocean NINO3 region sea-surface temperatures (SSTs) from July to September (JAS) are significantly correlated with both the concurrent August-September (AS) rainfall (r = -0.75) and the following November-December (ND) rainfall (r = 0.57), but with opposite signs. When station data are separated into uni- and bimodal sites, it becomes clear that the importance of ENSO events is different in the two zones. In the unimodal zone, El Nino events are associated with a depression of the August peak in rainfall, but a lengthening of the season, potentially providing an opportunity for growing later-maturing crops. At bimodal sites, there is very little impact in August but November rainfall is enhanced in El Nino years and depressed in La Nina years. Given a forecast of ENSO, the primary strategies that will be useful in farm management will differ by rainfall zone and will revolve around the choice of crop or cultivar and the timing of planting in order to make optimal use of the growing period. Copyright (C) 2000 Royal Meteorological Society. C1 Columbia Univ, Ctr Climate Syst Res, Columbia, NY USA. Rockefeller Fdn, Kawanda Agr Res Inst, Kampala, Uganda. RP Phillips, J (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 21 TC 40 Z9 40 U1 1 U2 6 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD FEB PY 2000 VL 20 IS 2 BP 171 EP 182 DI 10.1002/(SICI)1097-0088(200002)20:2<171::AID-JOC471>3.0.CO;2-O PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 289QP UT WOS:000085633700004 ER PT J AU Sherif, SA Lear, WE Steadham, JM Hunt, PL Holladay, JB AF Sherif, SA Lear, WE Steadham, JM Hunt, PL Holladay, JB TI Analysis and modeling of a two-phase jet pump of a thermal management system for aerospace applications SO INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES LA English DT Article DE jet pumps; ejectors; two-phase flow; aerospace thermal management ID PERFORMANCE AB Jet pumps are devices capable of pumping fluids to a higher pressure by inducing the motion of a secondary fluid employing a high-speed primary fluid. The main components of a jet pump are a primary nozzle, secondary fluid injectors, a mixing chamber, a throat, and a diffuser. The work described in this paper models the flow of a two-phase primary fluid inducing a secondary liquid (saturated or subcooled) injected into the jet pump mixing chamber. The model is capable of accounting for phase transformations due to compression, expansion, and mixing. The model is also capable of incorporating the effects of the temperature and pressure dependency in the analysis. The approach adopted utilizes an isentropic constant-pressure mixing in the mixing chamber and at times employs iterative techniques to determine the flow conditions in the different parts of the jet pump. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 Univ Florida, Dept Mech Engn, Gainesville, FL 32611 USA. NASA, George C Marshall Space Flight Ctr, Thermal & Life Support Div, Huntsville, AL 35812 USA. RP Sherif, SA (reprint author), Univ Florida, Dept Mech Engn, 228 MEB,POB 116300, Gainesville, FL 32611 USA. NR 13 TC 19 Z9 21 U1 0 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7403 J9 INT J MECH SCI JI Int. J. Mech. Sci. PD FEB PY 2000 VL 42 IS 2 BP 185 EP 198 DI 10.1016/S0020-7403(98)00123-4 PG 14 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 237YZ UT WOS:000082685300003 ER PT J AU Yedavalli, RK Ashokkumar, CR AF Yedavalli, RK Ashokkumar, CR TI Time response bounds for linear parametric uncertain systems SO INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE LA English DT Article ID ROBUSTNESS AB Parametric uncertainties in linear time-invariant state-space models introduce perturbations in the eigenvalues ann eigenvectors (eigenstructure), which modify the proper ties of a nominal system. Besides stability by the perturbed eigenvalues, controllability, observability, transient and steady-state values, etc., are some basic properties of a linear system significantly influenced by the perturbed eigenvectors, In this paper, time response analysis of parametric uncertain systems is considered First the bounds on eigenvectors and parametric uncertainties are established for the perturbed eigenvalues to reside in a set of distinct circular regions. Secondly, analysis of such parametric uncertain systems is discussed by presenting bounds on the perturbed state variables in time coordinate. These bound's are then investigated for norm-bounded and structured uncertainty classifications. Input-output analysis of uncertain systems is illustrated using the initial conditions and input functions. C1 Ohio State Univ, Dept Aerosp Engn Appl Mech & Aviat, Columbus, OH 43210 USA. N Carolina Agr & Technol State Univ, NASA, Ctr Aerosp Res, Greensboro, NC 27411 USA. RP Yedavalli, RK (reprint author), Ohio State Univ, Dept Aerosp Engn Appl Mech & Aviat, Columbus, OH 43210 USA. NR 19 TC 2 Z9 2 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND SN 0020-7721 J9 INT J SYST SCI JI Int. J. Syst. Sci. PD FEB PY 2000 VL 31 IS 2 BP 177 EP 188 DI 10.1080/002077200291299 PG 12 WC Automation & Control Systems; Computer Science, Theory & Methods; Operations Research & Management Science SC Automation & Control Systems; Computer Science; Operations Research & Management Science GA 274GF UT WOS:000084755000005 ER PT J AU Chepfer, H Goloub, P Spinhirne, J Flamant, PH Lavorato, M Sauvage, L Brogniez, G Pelon, J AF Chepfer, H Goloub, P Spinhirne, J Flamant, PH Lavorato, M Sauvage, L Brogniez, G Pelon, J TI Cirrus cloud properties derived from POLDER-1/ADEOS polarized radiances: First validation using a ground-based lidar network SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID ICE CRYSTAL CLOUDS; MULTIPLE-SCATTERING; WATER DROPLET; LASER-LIGHT; MIXED-PHASE; POLDER; RETRIEVAL; AEROSOLS; LAND AB Bidirectional polarized reflectances measured with the POLDER-I instrument on board Advanced Earth Observing Satellite-1 have been used to infer cloud altitude and thermodynamical phase (ice/liquid) at a global scale. This paper presents a validation of these properties for cirrus clouds. The validation presented here is based on comparisons between POLDER-I retrievals and measurements collected with a ground-based lidar network. The scale differences between POLDER measurements and lidar data are treated by selecting homogeneous and stable cloud layers. These comparisons show that the cloud altitude retrieval with POLDER is valid for optically thick cloud, and nonvalid for semitransparent and thin cirrus clouds. The limitations of the cloud altitude retrieval method are analyzed by using both comparisons between POLDER and lidar and simulations of the bidirectional polarized reflectances performed with a radiative transfer code to assess a threshold of validity of the POLDER retrieval method. The comparisons of lidar and POLDER data show that the cloud thermodynamical phase (ice/liquid) retrieval is satisfactory, and examples of cloud thermodynamical phase retrieval are presented as a function of cloud temperatures. C1 Ecole Polytech, Meteorol Dynam Lab, F-91128 Palaiseau, France. Univ Lille 1, Opt Atmospher Lab, F-59655 Villeneuve Dascq, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CEILAP, Villa Martelli, Argentina. Univ Paris 06, Serv Aeron, Paris, France. RP Chepfer, H (reprint author), Ecole Polytech, Meteorol Dynam Lab, F-91128 Palaiseau, France. NR 27 TC 19 Z9 21 U1 2 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD FEB PY 2000 VL 39 IS 2 BP 154 EP 168 DI 10.1175/1520-0450(2000)039<0154:CCPDFP>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 302CX UT WOS:000086348700003 ER PT J AU Chou, SH Zhao, WZ Chou, MD AF Chou, SH Zhao, WZ Chou, MD TI Surface heat budgets and sea surface temperature in the pacific warm pool during TOGA COARE SO JOURNAL OF CLIMATE LA English DT Article ID ATMOSPHERE RESPONSE EXPERIMENT; WESTERN EQUATORIAL PACIFIC; MIXED-LAYER; RADIATION BUDGETS; TURBULENT FLUXES; SOLAR-RADIATION; WIND BURST; OCEAN; SSM/I AB The daily mean heat and momentum fluxes at the surface derived from the Special Sensor Microwave/Imager and Japan's Geostationary Meteorological Satellite radiance measurements are used to study the temporal and spatial variability of the surface energy budgets and their relationship to the sea surface temperature during the Coupled Ocean-Atmosphere Response Experiment intensive observing period (IOP). For three time legs observed during the IOP, the retrieved surface fluxes compare reasonably well with those from the Improved Meteorological Instrument (IMET) buoy, RV Moana Wave, and RV Wecoma. The characteristics of surface heat and momentum fluxes are very different between the southern and northern warm pool. In the southern warm pool, the net surface hear flux is dominated by solar radiation, which is, in turn, modulated by the two Madden-Julian oscillations. The surface winds are generally weak, leading to a shallow ocean mixed layer The solar radiation penetrating through the bottom of the mixed laver is significant, and the change in the sea surface temperature during the IOP does not follow the net surface heat flux. In the northern warm pool, the northeasterly trade wind is strong and undergoes strong seasonal variation. The variation of the net surface heat nux is dominated by evaporation. The two westerly wind bursts associated with the Madden-Julian oscillations seem to have little effect on the net surface heat flux. The ocean mixed layer is deep, and the solar radiation penetrating through the bottom of the mixed layer is small. As opposed to the southern warm pool, the trend of the sea surface temperature in the northern warm pool during the IOP is in agreement with the variation of the net beat flux at the surface. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. SM&A Corp, Largo, MD USA. RP Chou, SH (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 912, Greenbelt, MD 20771 USA. NR 46 TC 16 Z9 17 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD FEB 1 PY 2000 VL 13 IS 3 BP 634 EP 649 DI 10.1175/1520-0442(2000)013<0634:SHBASS>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 301GY UT WOS:000086303500008 ER PT J AU Su, CH Feth, S Lehoczky, SL AF Su, CH Feth, S Lehoczky, SL TI In situ partial pressure measurements and visual observation during crystal growth of ZnSe by seeded physical vapor transport SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE ZnSe crystals; in situ measurements; partial pressure; vapor growth ID MASS FLUX; CDS AB An in situ monitoring furnace was constructed with side windows to perform partial pressure measurements by optical absorption and visual observation of the growing crystal. A fused silica growth ampoule with a 4.5 cm long square tube between the source and the seed was prepared for the optical absorption measurements. A ZnSe crystal was grown by the seeded physical vapor transport (PVT) technique in a horizontal configuration. The growth temperature was 1120 degrees C and the furnace translation rate was 3 mm/day. Partial pressures of Se-2, P-Se2, at three locations along the length of the growth ampoule were measured at 90 min intervals during the growth process. The measured PSe2 were in the range of 2.0-6.5 x 10(-3) atm. The P-Se2 results indicate that the partial pressure profile was inconsistent with the predictions of the one-dimensional diffusion mass transport model and that the source composition shifted towards Se-rich during the run, i.e. the grown crystal was more Zn-rich than the source. The visual observation showed that the seed crystal first etched back, with greater thermal etching occurring along the edges of the seed crystal. Once the growth started, the crystal grew in a predominately contactless mode and facets were evident during growth. The crystal did not grow symmetrically, which is believed to be due to the unintentional asymmetry of the radial thermal profile in the furnace. Published by Elsevier Science B.V. C1 NASA, George C Marshall Space Flight Ctr, Sci Directorate, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. RP Su, CH (reprint author), NASA, George C Marshall Space Flight Ctr, Sci Directorate, Micrograv Sci & Applicat Dept, SD47, Huntsville, AL 35812 USA. RI Feth, Shari/F-6302-2013 OI Feth, Shari/0000-0003-3545-5649 NR 12 TC 4 Z9 4 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD FEB PY 2000 VL 209 IS 4 BP 687 EP 694 DI 10.1016/S0022-0248(99)00631-4 PG 8 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 287LZ UT WOS:000085508500018 ER PT J AU Gross, RS AF Gross, RS TI Combinations of Earth-orientation measurements: SPACE97, COMB97, and POLE97 SO JOURNAL OF GEODESY LA English DT Article DE earth rotation; combination; Kalman filter ID ROTATION AB Independent Earth-orientation measurements taken by the space-geodetic techniques of lunar and satellite laser ranging, very-long-baseline interferometry, and the global positioning system have been combined using a Kalman filter. The resulting combined Earth-orientation series, SPACE97, consists of values and uncertainties for universal time, polar motion, and their rates spanning the period 28 September 1976 to 3 January 1998 at daily intervals. The space-geodetic measurements used to generate SPACE97 have then been combined with optical astrometric measurements to form two additional combined Earth-orientation series: (1) COMB97, consisting of values and uncertainties for universal time, polar motion, and their rates spanning the period 20 January 1962 to 1 January 1998 at 5-day intervals, and (2) POLE97, consisting of values and uncertainties for polar motion and its rate spanning the period 20 January 1900 to 21 December 1997 at monthly intervals. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gross, RS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 238-332, Pasadena, CA 91109 USA. NR 21 TC 31 Z9 38 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0949-7714 J9 J GEODESY JI J. Geodesy PD FEB PY 2000 VL 73 IS 12 BP 627 EP 637 DI 10.1007/s001900050001 PG 11 WC Geochemistry & Geophysics; Remote Sensing SC Geochemistry & Geophysics; Remote Sensing GA 285KU UT WOS:000085388900001 ER PT J AU Chen, JL Shum, CK Wilson, CR Chambers, DP Tapley, BD AF Chen, JL Shum, CK Wilson, CR Chambers, DP Tapley, BD TI Seasonal sea level change from TOPEX/Poseidon observation and thermal contribution SO JOURNAL OF GEODESY LA English DT Article DE TOPEX/Poseidon; sea-level change; thermal effect AB Seasonal steric sea-level change due to temperature variation in the mixing layer is assessed using space-measured sea-surface temperature data and historical in situ temperature measurements. The results are compared with TOPEX/Poseidon satellite: altimeter measurement at different large spatial scales. It is indicated that thermal effect accounts for much of the observed seasonal variability, especially when averaging over zonal regions. Some regional seasonal patterns of sea-level anomalies in the tropical oceans are well represented by the thermal model prediction. Systematic differences are shown between TOPEX/Poseidon observation and thermal contribution at a 1-2 cm level. The potential causes for these differences are discussed, including water mass exchanges among the atmosphere, land, and oceans, and error sources in the steric result and geophysical corrections applied in TOPEX/Poseidon data. C1 Univ Texas, Ctr Space Res, Austin, TX 78759 USA. Univ Texas, Dept Geol Sci, Austin, TX 78759 USA. Ohio State Univ, Dept Civil & Environm Engn & Geodet Sci, Columbus, OH USA. NASA Headquarters, Washington, DC USA. RP Chen, JL (reprint author), Univ Texas, Ctr Space Res, 3925 W Braker Lane,Suite 200, Austin, TX 78759 USA. OI Chambers, Don/0000-0002-5439-0257 NR 16 TC 41 Z9 53 U1 0 U2 4 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0949-7714 J9 J GEODESY JI J. Geodesy PD FEB PY 2000 VL 73 IS 12 BP 638 EP 647 DI 10.1007/s001900050002 PG 10 WC Geochemistry & Geophysics; Remote Sensing SC Geochemistry & Geophysics; Remote Sensing GA 285KU UT WOS:000085388900002 ER PT J AU Neugebauer, M Smith, EJ Ruzmaikin, A Feynman, J Vaughan, AH AF Neugebauer, M Smith, EJ Ruzmaikin, A Feynman, J Vaughan, AH TI The solar magnetic field and the solar wind: Existence of preferred longitudes SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GEOMAGNETIC-ACTIVITY; SECTOR STRUCTURE; ROTATION; EVOLUTION; SCALE; STARS AB Direct measurements of the solar wind speed and the radial component of the interplanetary magnetic field acquired over more than three solar cycles are used to search for signatures of a persistent dependence of solar wind properties on solar longitude. Two methods of analysis are used, One finds the rotation period that maximizes the amplitude of longitudinal variations of both interplanetary and near-Earth data mapped to the Sun. The other is based on power spectra of near-Earth and near-Venus data. The two methods give the same result. Preferred-longitude effects are found for a synodic solar rotation period of 27.03 +/- 0.02 days. Such high precision is attained by using several hundred thousand hourly averages of the solar wind speed and magnetic field. The 27.03-day periodicity is dominant only over long periods of time; other periodicities are often more prominent for shorter intervals such as a single solar cycle or less. The 27.03-day signal is stronger and more consistent in the magnetic field than in the solar wind speed and is stronger for intervals of high and declining solar activity than for intervals of low or rising activity. On average, solar magnetic field lines in the ecliptic plane point outward on one side of the Sun and inward on the other, reversing direction approximately every 11 years while maintaining the same phase. The data are consistent with a model in which the solar magnetic dipole returns to the same longitude after each reversal. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Neugebauer, M (reprint author), CALTECH, Jet Prop Lab, MS 160-506,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 28 TC 64 Z9 66 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD FEB 1 PY 2000 VL 105 IS A2 BP 2315 EP 2324 DI 10.1029/1999JA000298 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 281YP UT WOS:000085189300001 ER PT J AU Strachan, L Panasyuk, AV Dobrzycka, D Kohl, JL Noci, G Gibson, SE Biesecker, DA AF Strachan, L Panasyuk, AV Dobrzycka, D Kohl, JL Noci, G Gibson, SE Biesecker, DA TI Latitudinal dependence of outflow velocities from OVI Doppler dimming observations during the Whole Sun Month SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ULTRAVIOLET CORONAGRAPH SPECTROMETER; SOLAR CORONA; WIND; DISTRIBUTIONS; TEMPERATURE; HYDROGEN AB Empirical determinations of outflow velocities in the solar corona provide a much needed constraint, along with density and temperature determinations, of the acceleration and heating mechanisms in the extended corona. Much progress has been made an density determinations from white light polarized brightness observations but outflow velocities have been more difficult to determine. present the first determinations of outflow velocities versus height and latitude based on a three-dimensional (3-D) reconstruction of the O VI 1032 and 1037 Angstrom emissivities. The Doppler dimming (and pumping) of the local emissivities give true localized outflow velocities at the selected locations in the extended corona from similar to 1.75 to 2.75 solar radii. The velocities are based on an empirical model of the corona which is constrained by the reconstructed O VI emissivities derived from the SOHO Ultraviolet Coronagraph Spectrometer (UVCS) synoptic observations and by electron density determinations based on white light measurements from the SOHO Large Angle Spectroscopic Coronagraph (LASCO) and Mauna Loa Solar Observatory (MLSO) Mk III coronameter. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Florence, I-50121 Florence, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Washington, DC 20064 USA. Univ Birmingham, Birmingham B15 2TT, W Midlands, England. RP Strachan, L (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Gibson, Sarah/A-9189-2011 NR 31 TC 31 Z9 31 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD FEB 1 PY 2000 VL 105 IS A2 BP 2345 EP 2356 DI 10.1029/1999JA900459 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 281YP UT WOS:000085189300004 ER PT J AU Burlaga, LF Lazarus, AJ AF Burlaga, LF Lazarus, AJ TI Lognormal distributions and spectra of solar wind plasma fluctuations: Wind 1995-1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; INTERMITTENT TURBULENCE; MULTIFRACTAL STRUCTURE; STREAMS; 1-AU; AU AB The fluctuations in the hour averages of the speed V, density N, and proton temperature T at 1 AU are large, intermittent, and spiky on a scale of a year. The lognormal distribution is a good model for the distribution of measurements of these variables made at 1 AU during 1996, 1997, and 1998, near solar minimum, and during the rising phase of the solar cycle. The lognormal distribution is less satisfactory as a model for the data obtained during 1995, when corotating streams were present. For that year the distributions of V, N, and T were double-peaked; nevertheless, the number of observations associated with the fast wind distribution was only 12-17%. Shocks, corotating streams, interaction regions, signatures of the sources of the streams, and the heliospheric plasma sheet are present in the data, but each of these features has its own variability. Taken together, these components and their interactions result in episodic signals and distribution functions with large tails. There remains a need for dynamical models of the solar wind that incorporate and describe both deterministic and statistical properties of the solar wind. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. RP Burlaga, LF (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. NR 27 TC 43 Z9 44 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD FEB 1 PY 2000 VL 105 IS A2 BP 2357 EP 2364 DI 10.1029/1999JA900442 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 281YP UT WOS:000085189300005 ER PT J AU Koster, RD Suarez, MJ Heiser, M AF Koster, RD Suarez, MJ Heiser, M TI Variance and predictability of precipitation at seasonal-to-interannual timescales SO JOURNAL OF HYDROMETEOROLOGY LA English DT Article ID GENERAL-CIRCULATION MODELS; SEA-SURFACE TEMPERATURE; OCEAN-ATMOSPHERE MODEL; SOIL-MOISTURE; PARAMETERIZATION SCHEMES; INTERCOMPARISON PROJECT; GLOBAL PRECIPITATION; SOUTHERN-OSCILLATION; DATA ASSIMILATION; AMIP SIMULATIONS AB A series of atmospheric general circulation model simulations, spanning a total of several thousand years, is used to assess the impact of land surface and ocean boundary conditions on the seasonal-to-interannual variability and predictability of precipitation in a coupled modeling system. In the first half of the analysis, which focuses on precipitation variance, the contributions of ocean, atmosphere, and land processes to this variance are characterized, to first order, with a simple linear model. The resulting clean separation of the contributions leads to two results: 1) land and ocean processes have essentially different domains of influence, that is, the amplification of precipitation variance by land-atmosphere feedback is most important outside of the regions (mainly in the Tropics) that are most affected by sea surface temperatures; and 2) the strength of land-atmosphere feedback in a given region is controlled largely by the relative availability of energy and water there. In the second half of the analysis, the potential for seasonal-to-interannual predictability of precipitation is quantified under the assumption that all relevant surface boundary conditions tin the ocean and on land) are themselves perfectly predictable. Although the chaotic nature of the atmospheric circulation imposes fundamental limits on precipitation predictability in many regions, foreknowledge of sea surface temperature contributes significantly to predictability in the Tropics, and foreknowledge of land surface moisture state contributes significantly to predictability in transition zones between dry and humid climates. Thus, soil moisture initialization or assimilation in a seasonal-to-interannual forecasting system would be especially beneficial in these transition zones. C1 NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Atmospheres Lab, Greenbelt, MD 20771 USA. Gen Sci Corp, Beltsville, MD USA. RP Koster, RD (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Code 974, Greenbelt, MD 20771 USA. RI Koster, Randal/F-5881-2012 OI Koster, Randal/0000-0001-6418-6383 NR 49 TC 278 Z9 295 U1 1 U2 26 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 1525-755X J9 J HYDROMETEOROL JI J. Hydrometeorol. PD FEB PY 2000 VL 1 IS 1 BP 26 EP 46 DI 10.1175/1525-7541(2000)001<0026:VAPOPA>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 357DJ UT WOS:000089483000003 ER PT J AU Tumer, IY Wood, KL Busch-Vishniac, IJ AF Tumer, IY Wood, KL Busch-Vishniac, IJ TI A mathematical transform to analyze part surface quality in manufacturing SO JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID DECOMPOSITION; DIAGNOSIS AB The status of fault patterns on part surfaces can provide valuable in formation about the condition of a manufacturing system. Accurate detection of the part of the surface condition manufacturing ensures the fault-free manufacturing of high-quality parts , as well as helping. To address this problem, we introduce an alternative mathematical transform that has the potential to detect faults in manufacturing machines by decomposing signals into individual components. Specifically, the paper focuses on the decomposition of numerically generated data using the Karhunen-Loeve transform to study a variety of signals from manufacturing. The potential utility of the proposed technique is then discussed in the context of understanding a manufacturing process under constant development. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Texas, Austin, TX 78712 USA. Johns Hopkins Univ, Whiting Sch Engn, Baltimore, MD 21218 USA. RP Tumer, IY (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 27 TC 3 Z9 3 U1 1 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 1087-1357 J9 J MANUF SCI E-T ASME JI J. Manuf. Sci. Eng.-Trans. ASME PD FEB PY 2000 VL 122 IS 1 BP 273 EP 279 DI 10.1115/1.538904 PG 7 WC Engineering, Manufacturing; Engineering, Mechanical SC Engineering GA 404PM UT WOS:000167109600033 ER PT J AU Olsen, GT Wolfenden, A Hebsur, MG AF Olsen, GT Wolfenden, A Hebsur, MG TI Experimental investigation of the dynamic elastic modulus and vibration damping in MoSi2-30%Si3N4 as a function of temperature SO JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE LA English DT Article DE ceramics; molybdenum disilicide; silicon nitride; Young's modulus; damping AB The dynamic elastic modulus, E, and vibration damping of molybdenum disilicide (MoSi2) with 30% volume addition of silicon nitride (Si3N4) were measured at varying temperatures using the piezoelectric ultrasonic composite oscillator technique (PUCOT), The value of the elastic modulus of the composite was observed to decrease as temperature, T, was increased. The value of dE/dT of MoSi2 was determined to be -0.03 GPa/K, The vibration damping of MoSi2-30%Si3N4 increased as temperature was increased, with an effective activation energy of 0.076 eV/atom, This was an average over the entire temperature range, but two distinct slopes were observed in the plot of damping versus inverse temperature. C1 Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Olsen, GT (reprint author), Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NR 8 TC 2 Z9 2 U1 1 U2 2 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 USA SN 1059-9495 J9 J MATER ENG PERFORM JI J. Mater. Eng. Perform. PD FEB PY 2000 VL 9 IS 1 BP 116 EP 119 DI 10.1361/105994900770346376 PG 4 WC Materials Science, Multidisciplinary SC Materials Science GA 296MB UT WOS:000086027200018 ER PT J AU Cerf, NJ AF Cerf, NJ TI Asymmetric quantum cloning in any dimension SO JOURNAL OF MODERN OPTICS LA English DT Article ID UNCERTAINTY RELATIONS; CHANNELS; STATES AB A family of asymmetric cloning machines for N-dimensional quantum states is introduced. These machines produce two imperfect copies of a single state that emerge from non-identical Heisenberg channels. The trade-off between the quality of the copies imposed by quantum mechanics is shown to result from a complementarity akin to the Heisenberg uncertainty principle. More specifically, the probability distributions of the error operators affecting the two copies are the square modulus of two functions related by a Fourier transform. A no-cloning inequality is derived for the special case of isotropic cloners, quantifying the impossibility of perfect cloning: if pi(a) and pi(b) are the depolarizing fractions associated with the two copies, the domain in (pi(a)(1/2), pi(b)(1/2))-space located inside a particular ellipse representing close-to-perfect cloning is forbidden. More generally, an entropic no-cloning uncertainty relation is also discussed. Finally, the class of asymmetric cloning machines for quantum bits is investigated in detail, and a connection with the capacity of the Pauli channel is displayed. C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Kellogg Radiat Lab, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Informat & Comp Technol Res Sect, Pasadena, CA 91109 USA. RP Cerf, NJ (reprint author), Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. NR 22 TC 145 Z9 149 U1 2 U2 6 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND SN 0950-0340 J9 J MOD OPTIC JI J. Mod. Opt. PD FEB-MAR PY 2000 VL 47 IS 2-3 BP 187 EP 209 DI 10.1080/095003400148141 PG 23 WC Optics SC Optics GA 282TL UT WOS:000085234900007 ER PT J AU Brown, LR Plymate, C AF Brown, LR Plymate, C TI Experimental line parameters of the oxygen A band at 760 nm SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article DE oxygen; A band; line parameters; intensities; broadening coefficients; widths; pressure shifts; calibration; standards ID FOURIER-TRANSFORM SPECTROSCOPY; DIODE-LASER SPECTROSCOPY; HIGH-RESOLUTION; A-BAND; BROADENING COEFFICIENTS; WATER-VAPOR; ABSORPTION-SPECTROSCOPY; INTENSITIES; O-2; SPECTRUM AB To support atmospheric remote sensing applications, line positions, intensities, self- and nitrogen-broadened linewidths and their temperature dependences and pressure-induced shifts in line positions at room temperature were measured up to J' and N' = 22 for the oxygen A band at 13 122 cm(-1). Line intensities were obtained with 1% precisions and 2% absolute accuracies using absorption spectra recorded at Doppler-limited (0.02 cm(-1)) resolution with the McMath Fourier transform spectrometer (FTS) located at Kitt Peak National Observatory/National Solar Observatory in Arizona. The oxygen line positions were calibrated using near-infrared transitions of the 2-0 and 3-0 bands of CO as secondary standards. The intensities and positions of seven H2O lines near 13 900 cm(-1) were also remeasured to validate the FTS performance. The O-2 intensities fell within 1% of the values currently assumed fur the molecular databases, but it was found that broadening coefficients and line positions should be revised for the A band of molecular oxygen. a 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Solar Observ, Tucson, AZ USA. RP Brown, LR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 58 TC 92 Z9 92 U1 1 U2 14 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD FEB PY 2000 VL 199 IS 2 BP 166 EP 179 DI 10.1006/jmsp.1999.8012 PG 14 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 278NY UT WOS:000084996900003 ER PT J AU Kshirsagar, RJ Giver, LP Chackerian, C AF Kshirsagar, RJ Giver, LP Chackerian, C TI Rovibrational intensities of the (00(0)3)<-(10(0)0) dyad absorption bands of (CO2)-C-12-O-16 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article DE carbon dioxide; intensities; near IR; absorption bands ID VENUS; PARAMETERS; NIGHTSIDE AB Absolute line intensities of (CO2)-C-12-O-16 are experimentally measured for the first time for the (00(0)3)(I) <-- (10(0)0)(II) band at 5687.17 cm(-1) and the (00(0)3)(I) <-- (10(0)0), band at 5584.39 cm(-1), The spectra were obtained using a Bomem DA8 Fourier transform spectrometer and a 25-m base-path White cell at NASA-Ames Research Center. The rotationless bandstrengths at a temperature of 296 K and the Herman-Wallis parameters are S-vib(0) = 6.68(30) X 10(-25) cm(-1)/(molecule/cm(2)); A(1) = 1.4(9) x 10(-4), and A(2) = -1.1(5) x 10(-5) for the (00(0)3)(I) <-- (10(0)0)(II), band and S-vib(0) = 6.07(22) x 10(-25) cm(-1)/(molecule/cm(2)); A(1) = 5.2(1.5) x 10(-4) and A(2) = -4.0(7) x 10(-5) for the (00(0)3)(I) <-- (10(0)0)(I) band. C1 NASA, Ames Res Ctr, Atmospher Phsy Branch, Moffett Field, CA 94035 USA. RP Kshirsagar, RJ (reprint author), NASA, Ames Res Ctr, Atmospher Phsy Branch, N 245-4, Moffett Field, CA 94035 USA. NR 16 TC 7 Z9 8 U1 1 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD FEB PY 2000 VL 199 IS 2 BP 230 EP 235 DI 10.1006/jmsp.1999.8011 PG 6 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 278NY UT WOS:000084996900009 ER PT J AU Schneegurt, MA Tucker, DL Ondr, JK Sherman, DM Sherman, LA AF Schneegurt, MA Tucker, DL Ondr, JK Sherman, DM Sherman, LA TI Metabolic rhythms of a diazotrophic cyanobacterium, Cyanothece sp strain ATCC 51142, heterotrophically grown in continuous dark SO JOURNAL OF PHYCOLOGY LA English DT Article DE circadian rhythms; cyanobacteria; cyanophycin; dinitrogen; glycogen granules; heterotrophy; nitrogen fixation; nitrogenase; photosynthesis ID SYNECHOCOCCUS SP RF-1; CIRCADIAN-RHYTHM; POLYACRYLAMIDE GELS; PLECTONEMA-BORYANUM; NITROGEN-FIXATION; ATCC-51142; PROTEINS; CHLOROPHYLL; PROKARYOTES; COMPONENTS AB Aerobic unicellular cyanobacteria temporally separate nitrogen fixation and photosynthetic activity to protect oxygen-sensitive nitrogenase, Diurnal metabolic oscillations in the unicellular diazotroph, Cyanothece sp, str, CGD occurred even when cells were gown under continuous dark conditions, as determined in this study. The metabolic processes of nitrogen fixation, respiration, carbohydrate storage, and nitrogen storage all remained highly synchronized during heterotrophic growth, despite the absence of Light signals. This shows the importance of circadian regulation in this unicellular cyanobacterium, The nitrogenase complex is apparently tightly regulated at the transcriptional and post-translational levels. Carbohydrates accumulated during the subjective light phase were metabolized in a burst of respiration in the subjective dark phase. The utilization of carbohydrates occurred at the same time as the intense period of nitrogenase activity and downregulation of the capacity for photosynthetic oxygen evolution. Abundance of the D1 protein of photosystem II in Cyanothece sp, str, CGD remained relatively constant under continuous darkness, but the psbA transcript was more abundant in the subjective light phase. Accumulation of the psaAB gene products in photosystem I was highest in the subjective dark phase. The storage of fixed nitrogen as cyanophycin granules also exhibited periodic changes, with the amount of cyanophycin being greatest after the peak of nitrogenase activity. These results strongly implicate a circadian regulatory mechanism operating on these metabolic processes, independent of light cues, and stress the importance of circadian rhythms in global metabolic regulation in this unicellular cyanobacterium. C1 Purdue Univ, Dept Biol Sci, W Lafayette, IN 47907 USA. Purdue Univ, NASA, Specialized Ctr Res & Training, W Lafayette, IN 47907 USA. Purdue Univ, Dept Bot & Plant Pathol, W Lafayette, IN 47907 USA. RP Sherman, LA (reprint author), Purdue Univ, Dept Biol Sci, W Lafayette, IN 47907 USA. NR 42 TC 25 Z9 25 U1 1 U2 15 PU PHYCOLOGICAL SOC AMER INC PI LAWRENCE PA 810 EAST 10TH ST, LAWRENCE, KS 66044 USA SN 0022-3646 J9 J PHYCOL JI J. Phycol. PD FEB PY 2000 VL 36 IS 1 BP 107 EP 117 DI 10.1046/j.1529-8817.2000.99152.x PG 11 WC Plant Sciences; Marine & Freshwater Biology SC Plant Sciences; Marine & Freshwater Biology GA 294NN UT WOS:000085917500014 ER PT J AU Seraji, H AF Seraji, H TI Fuzzy Traversability Index: A new concept for terrain-based navigation SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article AB Fuzzy Traversability Index is introduced in this paper as a new and simple measure for quantifying the ease of traversal of natural terrains by field mobile robots. This index provides a simple means for incorporating the terrain quality data into the robot navigation strategy and is used for terrain-based navigation of held mobile robots. The Traversability Index is expressed by fuzzy sets that quantify the suitability of the terrain for traversal based on its geometrical and physical properties, such as slope, roughness, and hardness. This descriptive representation of terrain traversability in a natural language using linguistic variables and conditional statements is easily comprehensible, more appealing, and closer to human intuition than a mathematical formulation of traversability. A set of fuzzy navigation rules is developed using the Fuzzy Traversability Index to guide the robot toward the safest and the most traversable terrain. In addition, another set of fuzzy rules is developed to drive the robot from its initial position to a user-specified goal position. These two rule sets are integrated in a two-stage procedure for autonomous robot navigation without a priori map-based knowledge about the environment. In the first stage, the traverse-terrain and seek-goal rule sets make their individual, independent recommendations for robot turn and move commands. In the second stage, these recommendations are integrated by using appropriate weighting factors to generate the combined, coordinated recommendation for the robot navigation based on the robot status. Three simulation studies are presented to demonstrate the capability of the mobile robot to reach the goal safely while avoiding impassable terrains. (C) 2000 John Wiley & Sons, Inc. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 28 TC 32 Z9 35 U1 0 U2 2 PU JOHN WILEY & SONS INC PI HOBOKEN PA 111 RIVER ST, HOBOKEN, NJ 07030 USA SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD FEB PY 2000 VL 17 IS 2 BP 75 EP 91 DI 10.1002/(SICI)1097-4563(200002)17:2<75::AID-ROB1>3.0.CO;2-P PG 17 WC Robotics SC Robotics GA 277NJ UT WOS:000084939400001 ER PT J AU Miller, FJ Koenigsdorff, RW AF Miller, FJ Koenigsdorff, RW TI Thermal modeling of a small-particle solar central receiver SO JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article AB This paper presents a thermal model of a solar central receiver that volumetrically absorbs concentrated sunlight directly in a flowing gas stream seeded with submicron carbon particles. A modified six-flux radiation model is developed and used with the energy equation to calculate the three-dimensional radiant flux and temperature distributions in a cavity-type particle receiver. Results indicate that the receiver is capable of withstanding very high incident fluxes and delivering high temperatures. The receiver efficiency as a function of mass flow rate as well as the effect of particle oxidation on the temperature profiles are presented. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. Univ Appl Sci Biberach, D-88400 Biberach, Germany. RP Miller, FJ (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, MS 110-3, Cleveland, OH 44135 USA. NR 19 TC 33 Z9 33 U1 1 U2 8 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0199-6231 J9 J SOL ENERG-T ASME JI J. Sol. Energy Eng. Trans.-ASME PD FEB PY 2000 VL 122 IS 1 BP 23 EP 29 DI 10.1115/1.556277 PG 7 WC Energy & Fuels; Engineering, Mechanical SC Energy & Fuels; Engineering GA 404MY UT WOS:000167105400005 ER PT J AU Jimenez-Pique, E Dominguez-Rodriguez, A Martinez-Fernandez, J Lara-Curzio, E Singh, M AF Jimenez-Pique, E Dominguez-Rodriguez, A Martinez-Fernandez, J Lara-Curzio, E Singh, M TI Microstructure and mechanical properties of superplastically joined yttria-partially-stabilized zirconia (Y-PSZ) ceramics SO JOURNAL OF THE EUROPEAN CERAMIC SOCIETY LA English DT Article DE joining; mechanical properties; microstructure-final; plasticity; ZrO2-Y2O3 ID FLOW AB Joining of oxide ceramics has been recognized as a key issue in their successful utilization in a variety of demanding, high temperature applications. Superplastic joining of yttria-partially-stabilized zirconia (Y-PSZ) ceramics has been carried out to avoid the deleterious effects of joint interlayer materials. Microstructural characterization of superplastically formed joints indicate that the joint interface is indistinguishable from the bulk and that there is not grain growth across the interface. Compression tests conducted on double-notch specimens show that very good bonding was achieved in the superplastic joining process. From these experiments an underestimation of the shear strength was obtained as the specimens failed in the bulk. The room temperature flexural strength of joints measured had values up to 185 MPa. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Sevilla, Dept Fis Mat Condensada, Seville 41080, Spain. Div Met & Ceram, Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA. Dynacs Engn Co, NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Dominguez-Rodriguez, A (reprint author), Univ Sevilla, Dept Fis Mat Condensada, Box 1065, Seville 41080, Spain. RI MARTINEZ FERNANDEZ, JULIAN/K-1826-2012; OI MARTINEZ FERNANDEZ, JULIAN/0000-0002-1199-6638; Jimenez-Pique, Emilio/0000-0002-6950-611X; Dominguez-Rodriguez, Arturo/0000-0003-1598-5669 NR 10 TC 9 Z9 9 U1 1 U2 8 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0955-2219 J9 J EUR CERAM SOC JI J. European Ceram. Soc. PD FEB PY 2000 VL 20 IS 2 BP 147 EP 151 DI 10.1016/S0955-2219(99)00154-5 PG 5 WC Materials Science, Ceramics SC Materials Science GA 275RU UT WOS:000084834600008 ER PT J AU Timucin, DA Downie, JD AF Timucin, DA Downie, JD TI Phenomenological characterization of bacteriorhodopsin-D85N photocycle SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article ID PROTON TRANSLOCATION; PURPLE MEMBRANE; QUANTUM YIELD; ACID PH; FILMS; PHOTOISOMERIZATION; ABSORPTION; BLUE; STATE; PHOTOREACTIONS AB An operational characterization of the molecular photocycle of a genetic variant of bacteriorhodopsin, BR-D85N, is presented. Steady-state bleach spectra and pump-probe absorbance data are obtained with thick hydrated films that contain BR-D85N embedded in a gelatin host. Simple two- and three-state models are used to analyze the photocycle dynamics and to extract relevant information such as pure-state absorption spectra, photochemical-transition quantum efficiencies, and thermal lifetimes of dominant states that appear in the photocycle, the knowledge of which should facilitate the analysis and the design of optical applications based on this photochromic medium. The remarkable characteristics of this material and their implications from the viewpoint of optical data storage and processing are discussed. (C) 2000 Optical Society of America [S0740-3224(00)00202-2]. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Timucin, DA (reprint author), NASA, Ames Res Ctr, Mail Stop 269-3, Moffett Field, CA 94035 USA. NR 31 TC 3 Z9 4 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0740-3224 J9 J OPT SOC AM B JI J. Opt. Soc. Am. B-Opt. Phys. PD FEB PY 2000 VL 17 IS 2 BP 202 EP 212 DI 10.1364/JOSAB.17.000202 PG 11 WC Optics SC Optics GA 283AZ UT WOS:000085255100006 ER PT J AU Herrera-Fierro, P Shogrin, BA Jones, WR AF Herrera-Fierro, P Shogrin, BA Jones, WR TI Spectroscopic analysis of perfluoropolyether lubricant degradation during boundary lubrication SO LUBRICATION ENGINEERING LA English DT Article DE perfluoropolyethers; boundary lubrication; degradation ID POLARIZED INFRARED MICROSPECTROSCOPY; SURFACES; FLUID; TRIBOCHEMISTRY; HUMIDITY; BEHAVIOR; RAMAN; WEAR; FTIR AB The degradation of a branched perfluoropolyether (PFPE) under boundary lubrication conditions was studied using micro-Fourier transform infrared spectroscopy and micro-Raman spectroscopy Stainless steel (440C) discs coated with thin (600 Angstrom), uniform films of the PFPE were tested in a ball-on-disc apparatus until various levels of friction coefficient were attained. Discs were then examined using the above techniques. Wizen the friction coefficient surpassed the value obtained with an unlubricated control, the lubricant film had either been physically displaced or partially transformed into a "friction polymer.'' Infrared analysis of this "friction polymer" indicated the presence of a polymeric fluorinated acid species (RfCOOH). Raman spectroscopy indicated the presence of a graphitic amorphous carbon in the wear track and in the friction polymer Some reaction mechanisms are suggested to explain the results. C1 Ohio Aerosp Inst, Brookpk, OH 44142 USA. Case Western Reserve Univ, Cleveland, OH 44106 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Herrera-Fierro, P (reprint author), Ohio Aerosp Inst, Brookpk, OH 44142 USA. NR 28 TC 4 Z9 4 U1 1 U2 8 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD FEB PY 2000 VL 56 IS 2 BP 23 EP 29 PG 7 WC Engineering, Mechanical SC Engineering GA 283YR UT WOS:000085304100005 ER PT J AU Bar-Cohen, Y AF Bar-Cohen, Y TI Emerging NDT technologies and challenges at the beginning of the third millennium, part 2 SO MATERIALS EVALUATION LA English DT Article C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bar-Cohen, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 24 Z9 24 U1 0 U2 2 PU AMER SOC NON-DESTRUCTIVE TEST PI COLUMBUS PA 1711 ARLINGATE LANE PO BOX 28518, COLUMBUS, OH 43228-0518 USA SN 0025-5327 J9 MATER EVAL JI Mater. Eval. PD FEB PY 2000 VL 58 IS 2 BP 141 EP 150 PG 10 WC Materials Science, Characterization & Testing SC Materials Science GA 296CJ UT WOS:000086005200003 ER PT J AU Sawka, MN Convertino, VA Eichner, ER Schnieder, SM Young, AJ AF Sawka, MN Convertino, VA Eichner, ER Schnieder, SM Young, AJ TI Blood volume: importance and adaptations to exercise training, environmental stresses, and trauma/sickness SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Review DE erythrocyte volume; physical exercise; heat stress; hypoxia; microgravity; plasma volume; space; vascular volumes ID RECOMBINANT-HUMAN-ERYTHROPOIETIN; CENTRAL VENOUS-PRESSURE; MAXIMAL AEROBIC CAPACITY; OPERATION EVEREST-II; STAGE RENAL-DISEASE; PLASMA-VOLUME; HEAT-STRESS; INDUCED HYPERVOLEMIA; SUBMAXIMAL EXERCISE; PROLONGED EXERCISE AB This paper reviews the influence of several perturbations (physical exercise, heat stress, terrestrial altitude, microgravity, and trauma/sickness) on adaptations of blood volume (BV), erythrocyte volume (EV), and plasma volume (PV). Exercise training can induce BV expansion: PV expansion usually occurs immediately, but EV expansion takes weeks. EV and PV expansion contribute to aerobic power improvements associated with exercise training. Repeated heat exposure induces PV expansion but does nor alter EV. PV expansion does not improve thermoregulation, but EV expansion improves thermoregulation during exercise in the heat. Dehydration decreases PV (and increases plasma tonicity) which elevates heat strain and reduces exercise performance. High altitude exposure causes rapid (hours) plasma loss. During initial weeks at altitude, EV is unaffected, but a gradual expansion occurs with extended acclimatization. BV adjustments contribute, but are not key, to altitude acclimatization. Microgravity decreases PV and EV which contribute to orthostatic intolerance and decreased exercise capacity in astronauts. PV decreases may result from Lower set points for total body water and central venous pressure, while EV decreases may result from increased erythrocyte destruction. Trauma, renal disease, and chronic diseases cause anemia from hemorrhage and immune activation which suppresses erythropoiesis. The reestablishment of EV is associated with healing, improved life quality, and exercise capabilities for these injured/sick persons. C1 USA, Environm Med Res Inst, Thermal & Mt Med Div, Natick, MA 01760 USA. USA, Inst Surg Res, Ft Sam Houston, TX 78234 USA. Univ Oklahoma, Oklahoma City, OK USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Sawka, MN (reprint author), USA, Environm Med Res Inst, Thermal & Mt Med Div, Natick, MA 01760 USA. NR 172 TC 195 Z9 200 U1 3 U2 22 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD FEB PY 2000 VL 32 IS 2 BP 332 EP 348 DI 10.1097/00005768-200002000-00012 PG 17 WC Sport Sciences SC Sport Sciences GA 283TG UT WOS:000085291400012 PM 10694114 ER PT J AU Berry, S Hyers, RW Abedian, B Racz, LM AF Berry, S Hyers, RW Abedian, B Racz, LM TI Modeling of turbulent flow in electromagnetically levitated metal droplets SO METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE LA English DT Article ID SURFACE-TENSION; DENSITY; MELTS; POWER AB This article details an effort to improve the understanding and prediction of turbulent flow inside a droplet of molten metal levitated in an electromagnetic field. It is shown that the flow field in a test case, a nickel droplet levitated under microgravity conditions, is in the transitional regime between laminar and turbulent flow. Past research efforts have used laminar, enhanced viscosity, and k-epsilon turbulence models to describe the flow. The method highlighted in our study is the renormalization group (RNG) algorithm. We show that an accurate description of the turbulent eddy viscosity mu(T) is critical in order to obtain realistic velocity fields, and that mu(T) cannot be uniform in levitated droplets. The RNG method does not impose isotropic length or time scales on the flow field, thus allowing such nonuniform features to be captured. A number of other materials processing applications exhibit similarly complex flow characteristics, such as highly recirculating, transitional, and free surface flows, for which this modeling approach may prove useful. C1 MIT Lincoln Lab, Lexington, MA 02420 USA. MIT, Dept Mat Sci & Engn, Cambridge, MA 02139 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Tufts Univ, Dept Mech Engn, Medford, MA 02155 USA. RP Berry, S (reprint author), MIT Lincoln Lab, Lexington, MA 02420 USA. RI Hyers, Robert/G-3755-2010 NR 36 TC 17 Z9 17 U1 0 U2 2 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1073-5615 J9 METALL MATER TRANS B JI Metall. Mater. Trans. B-Proc. Metall. Mater. Proc. Sci. PD FEB PY 2000 VL 31 IS 1 BP 171 EP 178 DI 10.1007/s11663-000-0142-8 PG 8 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 283CE UT WOS:000085257900018 ER PT J AU Liske, J Webb, JK Williger, GM Fernandez-Soto, A Carswell, RF AF Liske, J Webb, JK Williger, GM Fernandez-Soto, A Carswell, RF TI Large-scale structure in the Lyman-alpha forest - II. Analysis of a group of 10 QSOs SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE intergalactic medium; quasars : absorption lines; large-scale structure of Universe ID HUBBLE-SPACE-TELESCOPE; INTERGALACTIC MEDIUM; LOW-REDSHIFT; ABSORPTION SYSTEMS; PHYSICAL-PROPERTIES; METAL ENRICHMENT; GASEOUS EXTENT; EVOLUTION; CLOUDS; ABSORBERS AB The spatial distribution of Ly alpha forest absorption systems towards 10 QSOs is analysed to search for large-scale structure over the redshift range 2.2 < z < 3.4. The QSOs form a closely spaced group on the sky and are concentrated within a 1-deg(2) field. We employ a technique based on the first and second moments of the transmission probability density function which is capable of identifying and assessing the significance of regions of over- or underdense Ly alpha absorption. We find evidence for large-scale structure in the distribution of Ly alpha forest absorption at the >99 per cent confidence level. In individual spectra we fmd overdense Ly alpha absorption on scales of up to 1200 km s(-1). There is also strong evidence for correlated absorption across line-of-sight pairs separated by <3 h(-1) proper Mpc (q(0) = 0.5). For larger separations the cross-correlation signal becomes progressively less significant. C1 Univ New S Wales, Sch Phys, Sydney, NSW 2052, Australia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. RP Liske, J (reprint author), Univ New S Wales, Sch Phys, Sydney, NSW 2052, Australia. RI Fernandez-Soto, Alberto/A-2443-2009 OI Fernandez-Soto, Alberto/0000-0002-5732-3121 NR 76 TC 18 Z9 19 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD FEB 1 PY 2000 VL 311 IS 4 BP 657 EP 667 DI 10.1046/j.1365-8711.2000.02966.x PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 285AX UT WOS:000085366900001 ER PT J AU McCracken, HJ Metcalfe, N Shanks, T Campos, A Gardner, JP Fong, R AF McCracken, HJ Metcalfe, N Shanks, T Campos, A Gardner, JP Fong, R TI Galaxy number counts - IV. Surveying the Herschel Deep Field in the near-infrared SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : evolution; galaxies : photometry; infrared : galaxies ID K-BAND SURVEY; CCD OBSERVATIONS; FAINT GALAXIES; LOW-REDSHIFT; WIDE-FIELD; EVOLUTION; PHOTOMETRY; IRREGULARS; SAMPLE; COLORS AB We present results from two new near-infrared imaging surveys. One survey covers 47.2 arcmin(2) to K(3 sigma) = 20 mag whilst a second, deeper catalogue covers a subarea of 1.8 arcmin(2) to K(3 sigma) = 22.75 mag. Over the entire area we have extremely deep optical photometry in four bandpasses (UBRI), allowing us to track the colour evolution of galaxies to very faint magnitude limits. Our K-band number counts are consistent with the predictions of non-evolving models with 0 less than or equal to q(0) less than or equal to 0.5. The K-selected (B - K) galaxy colour distributions from our surveys move sharply bluewards fainter than K similar to 20. At brighter magnitudes (K < 20 mag) our K-selected (B - K) distributions indicate a deficiency of red, early-type galaxies at z similar to 1 compared with the predictions of passively evolving models, which implies either a pure luminosity evolution (PLE) model, where star formation continues at a low level after an initial burst, or dynamical merging. At fainter magnitudes, the continuing bluewards trend observed in (B - K) can be explained purely in terms of passively evolving PLE models. We detect 0.5 +/- 0.1 galaxy arcmin(-2) with (I - K) > 4 and 19 < K < 20 mag. Although this is a factor of similar to 3 (2 sigma) more objects than in the recent survey of Berger et al., this is still lower than the predictions of standard passively evolving models and more consistent with PLE models containing small amounts of ongoing star formation. Our observed numbers of (I - K) > 4 galaxies at K - 20 are lower than the predictions of passively evolving models or PLE models with a low level of continuing star formation, suggesting that at least part of the larger deficiency observed in (B - K) at K - 20 may be caused by star formation rather than dynamical merging. As we and others have noted, the number redshift distribution at 18 < K < 19 of recent, deep K-selected redshift surveys is well fitted by non-evolving models, and passively evolving models with a Salpeter or Scale initial mass functions predict too many galaxies with z > 1. Dynamical merging is one possible solution to reduce the numbers of these galaxies but las we have suggested previously) a dwarf-dominated initial mass function for early-type galaxies could offer an alternative explanation; we show here that such a model reproduces well the optical-infrared colour distributions and K-band galaxy counts. C1 Univ Durham, Sci Labs, Dept Phys, Durham DH1 3LE, England. CSIC, Inst Matemat & Fis Fundamental, E-28006 Madrid, Spain. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP McCracken, HJ (reprint author), CNRS, Astron Spatiale Lab, F-13376 Marseille 12, France. NR 44 TC 67 Z9 67 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD FEB 1 PY 2000 VL 311 IS 4 BP 707 EP 718 DI 10.1046/j.1365-8711.2000.03096.x PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 285AX UT WOS:000085366900007 ER PT J AU Galloway, DK Giles, AB Greenhill, JG Storey, MC AF Galloway, DK Giles, AB Greenhill, JG Storey, MC TI Spectral variation in the X-ray pulsar GX 1+4 during a low-flux episode SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : symbiotic; pulsars : individual : GX 1+4; X-rays : stars ID ACCRETION TORQUES; NEUTRON-STARS; GX-1+4; LUMINOSITY; PROFILES AB The X-ray pulsar GX 1+4 was observed with the RXTE satellite for a total of 51 ks between 1996 July 19 and 21. During this period the flux decreased smoothly from an initial mean level of approximate to 6 x 10(36) erg s(-1) to a minimum of approximate to 4 x 10(35) erg s(-1) (2-60 keV, assuming a source distance of 10 kpc) before partially recovering towards the initial level at the end of the observation. BATSE pulse timing measurements indicate that a torque reversal took place approximately 10 d after this observation. Both the mean pulse profile and the photon spectrum varied significantly. The observed variation in the source may provide important clues as to the mechanism of torque reversals. The single best-fitting spectral model was based on a component originating from thermal photons with kT(0) approximate to 1 keV Comptonized by a plasma of temperature kT approximate to 7 keV. Both the flux modulation with phase during the brightest interval and the evolution of the mean spectra over the course of the observation are consistent with variations in this model component; with, in addition, a doubling of the column density n(H) contributing to the mean spectral change. A strong flare of duration less than or similar to 50 s was observed during the interval of minimum flux, with the peak flux approximate to 20 times the mean level. Although beaming effects are likely to mask the true variation in (M) over dot thought to give rise to the flare, the timing of a modest increase in flux prior to the flare is consistent with dual episodes of accretion resulting from successive orbits of a locally dense patch of matter in the accretion disc. C1 Univ Tasmania, Sch Math & Phys, Hobart, Tas 7001, Australia. Univ Sydney, Sch Phys, Special Res Ctr Theoret Astrophys, Sydney, NSW 2006, Australia. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Galloway, DK (reprint author), Univ Tasmania, Sch Math & Phys, GPO Box 252-21, Hobart, Tas 7001, Australia. RI Greenhill, John/C-8367-2013; OI Galloway, Duncan/0000-0002-6558-5121 NR 28 TC 8 Z9 8 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD FEB 1 PY 2000 VL 311 IS 4 BP 755 EP 761 DI 10.1046/j.1365-8711.2000.03135.x PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 285AX UT WOS:000085366900012 ER PT J AU Jennings, RT Baker, ES AF Jennings, RT Baker, ES TI Gynecological and reproductive issues for women in space: A review SO OBSTETRICAL & GYNECOLOGICAL SURVEY LA English DT Review ID MENTAL-RETARDATION; MICROGRAVITY; RADIATION; SURGERY; ENDOMETRIOSIS; EXPOSURE AB Women have been an integral part of United States space crews since the initial flight of Dr. Sally Ride in 1983, and a total of 40 women have been selected as U.S, astronauts. This article examines the reproductive and gynecological aspects of selecting, training, medically certifying, and flying women in space. Gynecological data from the astronaut selection cycles in 1991 to 1997 are reviewed. in addition, the reproductive implications of delaying childbearing for a career as an astronaut and the impact of new technology such as assisted reproductive techniques are examined. The reproductive outcomes of U.S, female astronauts after spaceflight are also presented. Because women have gained considerable operational experience on the Shuttle and Mir, the unique operational considerations for preflight certification, menstruation control and hygiene, contraception, and urination are discussed. Medical and surgical implications for women on long-duration missions to remote locations are still evolving, and enabling technologies for health care delivery are being developed. There has been considerable progress in the development of zero-gravity surgical techniques, including laparoscopy, thoracoscopy, and laparotomy. The concepts of prevention of illness, conversion of surgical conditions to medically treatable conditions, and surgical intervention for long-duration spaceflights are explored in detail. There currently are no operational gynecological or reproductive constraints for women that would preclude their successful participation in the exploration of our nearby solar system. C1 Univ Texas, Med Branch, Galveston, TX 77555 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Jennings, RT (reprint author), Univ Texas, Med Branch, 301 Univ Blvd, Galveston, TX 77555 USA. NR 26 TC 8 Z9 9 U1 0 U2 2 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0029-7828 J9 OBSTET GYNECOL SURV JI Obstet. Gynecol. Surv. PD FEB PY 2000 VL 55 IS 2 BP 109 EP 116 DI 10.1097/00006254-200002000-00025 PG 8 WC Obstetrics & Gynecology SC Obstetrics & Gynecology GA 390LD UT WOS:000166295700005 PM 10674254 ER PT J AU Tuma, ML Greer, LC Krasowski, MJ Oberle, LG Elam, KA Spina, DC AF Tuma, ML Greer, LC Krasowski, MJ Oberle, LG Elam, KA Spina, DC TI Results from real-time laser speckle-shift strain measurement system SO OPTICAL ENGINEERING LA English DT Article DE speckle shift; strain measurement; speckle pattern; hardware correlator AB A real-time two-color laser speckle-shift strain measurement system based on the technique of Yamaguchi was designed, built, and tested at room temperature. This noncontact 1-D system detects surface strain in a structural fiber as it is pulled in a tensile test machine. Interference or speckle patterns from the laser-illuminated fiber test specimen are recorded. As the fiber is pulled, its speckle pattern shifts in proportion to the strain, translational, and rotational components of the sample deformation. Shifting speckle patterns are detected using two linear CCD arrays with image processing performed in realtime by a hardware correlator. Surface strain is detected in fibers with diameters on the order of 100 mu m and can be resolved to 20 mu m/m. This system was designed to be robust and compact and generally does not require surface preparation of the structural fibers. (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)03502-9]. C1 NASA, Glenn Res Ctr, AKIMA, Cleveland, OH 44135 USA. RP Tuma, ML (reprint author), NASA, Glenn Res Ctr, AKIMA, MS 77-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 10 TC 8 Z9 8 U1 0 U2 1 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD FEB PY 2000 VL 39 IS 2 BP 498 EP 504 DI 10.1117/1.602399 PG 7 WC Optics SC Optics GA 285HW UT WOS:000085384500020 ER PT J AU Meinel, AB Meinel, MP AF Meinel, AB Meinel, MP TI Inflatable membrane mirrors for optical passband imagery SO OPTICAL ENGINEERING LA English DT Article DE space optics; inflatable membrane mirrors; visible passband inflatable mirrors AB Past investigations of membrane mirrors have led to the conclusion that they are not suitable for imaging in the visible. We reexamine this conclusion and discuss ways to circumvent the principal problems. A reanalysis of l'Garde measurements of a 6-mu m-thick membrane mirror corrects earlier interpretations of the "W curve" asymmetry. Correction of the classical Hencky aspheric shape of membrane mirrors is required to upgrade them for use in visible passbands. The theory of variable membrane thickness in a radial direction is presented. A numerical integration is done and a unique quadratic radial variation of thickness is found that corrects for the u(4) Hencky term. Two methods to fabricate such a membrane are presented. (C) 2000 society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)00802-3]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Meinel, AB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 18 Z9 19 U1 1 U2 3 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD FEB PY 2000 VL 39 IS 2 BP 541 EP 550 DI 10.1117/1.602393 PG 10 WC Optics SC Optics GA 285HW UT WOS:000085384500027 ER PT J AU Weber, AL AF Weber, AL TI Sugars as the optimal biosynthetic carbon substrate of aqueous life throughout the universe SO ORIGINS OF LIFE AND EVOLUTION OF THE BIOSPHERE LA English DT Article ID EARLY EARTH; ENERGY; GLYCERALDEHYDE; FORMALDEHYDE; ATMOSPHERE; PHOTOCHEMISTRY; THIOESTERS; MECHANISM; CATALYSIS; CHEMISTRY AB Our previous analysis of the energetics of metabolism showed that both the biosynthesis of amino acids and lipids from sugars, and the fermentation of organic substrates, were energetically driven by electron transfer reactions resulting in carbon redox disproportionation (Weber, 1997). Redox disproportionation - the spontaneous (energetically favorable) direction of carbon group transformation in biosynthesis - is brought about and driven by the energetically downhill transfer of electron pairs from more oxidized carbon groups (with lower half-cell reduction potentials) to more reduced carbon groups (with higher half-cell reduction potentials). In this report, we compare the redox and kinetic properties of carbon groups in order to evaluate the relative biosynthetic capability of organic substrates, and to identify the optimal biosubstrate. This analysis revealed that sugars (monocarbonyl alditols) are the optimal biosynthetic substrate because they contain the maximum number of biosynthetically useful high energy electrons/carbon atom while still containing a single carbonyl group needed to kinetically facilitate their conversion to useful biosynthetic intermediates. This conclusion applies to aqueous life throughout the Universe because it is based on invariant aqueous carbon chemistry - primarily, the universal reduction potentials of carbon groups. C1 NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Weber, AL (reprint author), NASA, Ames Res Ctr, SETI Inst, Mail Stop 239-4, Moffett Field, CA 94035 USA. NR 46 TC 21 Z9 22 U1 0 U2 5 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0169-6149 J9 ORIGINS LIFE EVOL B JI Orig. Life Evol. Biosph. PD JAN PY 2000 VL 30 IS 1 BP 33 EP 43 DI 10.1023/A:1006627406047 PG 11 WC Biology SC Life Sciences & Biomedicine - Other Topics GA 303FD UT WOS:000086410600005 PM 10836263 ER PT J AU Yu, N Maleki, L AF Yu, N Maleki, L TI Lifetime measurements of the 4f(14)5d metastable states in single ytterbium ions SO PHYSICAL REVIEW A LA English DT Article ID PAUL-STRAUBEL TRAP; FREQUENCY STANDARD; YB-II; TRANSITION; CLOCK AB The ytterbium ion has a rich level structure of low-lying states, and is one of the most widely used in experiments with trapped ions. We have measured the radiative lifetimes for the two 4f(14)5d metastable states using single ytterbium ions confined in a rf trap. The obtained lifetimes for D-3/2 and D-5/2 states are 52.7(2.4) and 7.0(0.4) ms, respectively. The results are in good agreement with previously measured values, but differ significantly from theoretical estimates. The P-1/2 branching ratio into D-3/2 has also been obtained from the experiment to be 0.0483 with a 9% uncertainty. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yu, N (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 19 TC 27 Z9 27 U1 1 U2 4 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD FEB PY 2000 VL 61 IS 2 AR 022507 DI 10.1103/PhysRevA.61.022507 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 284MV UT WOS:000085336900047 ER PT J AU Qian, YH Zhou, Y AF Qian, YH Zhou, Y TI Higher-order dynamics in lattice-based models using the Chapman-Enskog method. SO PHYSICAL REVIEW E LA English DT Article ID NAVIER-STOKES EQUATION; BOLTZMANN-EQUATION; GAS AUTOMATA; BGK MODELS AB In this paper, we investigate the existence of higher-order dynamics in lattice-based models. We have identified two conditions that determine whether a model would allow some Burnett-like equations when the Chapman-Enskog expansion is used. These two conditions are the number of the conserved quantity as well as the space and time discretization. We shall demonstrate these conditions by discussing (1) pure diffusion equation and (2) hydrodynamic equations. While the fact that diffusion equation allows the higher-order dynamics can be shown easily, we will illustrate that care must be taken when deriving Burnett-like equations for lattice-based hydrodynamics models using the Chapman-Enskog method. C1 Columbia Univ, Dept Appl Phys & Appl Math, New York, NY 10027 USA. IBM Corp, Div Res, Thomas J Watson Res Ctr, Yorktown Heights, NY 10598 USA. NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP Qian, YH (reprint author), Exa Corp, 450 Bedford St, Lexington, MA 02420 USA. NR 22 TC 11 Z9 12 U1 1 U2 7 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD FEB PY 2000 VL 61 IS 2 BP 2103 EP 2106 DI 10.1103/PhysRevE.61.2103 PG 4 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 285WD UT WOS:000085410600149 ER PT J AU Chung, SK Trinh, EH AF Chung, SK Trinh, EH TI Internal flow of an electrostatically levitated droplet undergoing resonant shape oscillation SO PHYSICS OF FLUIDS LA English DT Letter AB Experimental evidence of internal dc flow circulation within an electrostatically levitated, 3.4 mm diameter charged water drop oscillating in shape at a different amplitude is presented. The axisymmetric shape oscillations were excited using a continuously pulsed electrostatic field at the fundamental shape mode frequency (l=2) of the drop. It was found that the speed of the internal dc flow varied quadratically with respect to the oscillation amplitude without an observable minimum threshold. The implication of the observed internal flow is discussed with respect to the microgravity research facility and environment. (C) 2000 American Institute of Physics. [S1070-6631(00)02702-1]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chung, SK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 9 Z9 10 U1 0 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD FEB PY 2000 VL 12 IS 2 BP 249 EP 251 DI 10.1063/1.870326 PG 3 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 271MV UT WOS:000084598800002 ER PT J AU Ohsaka, K Trinh, EH AF Ohsaka, K Trinh, EH TI Resonant coupling of oscillating gas or vapor bubbles in water: An experimental study SO PHYSICS OF FLUIDS LA English DT Article ID VOLUME OSCILLATIONS; MONOPOLE EMISSION; SOUND; SHAPE; MODES AB Resonant coupling of oscillating gas or vapor bubbles in water is experimentally studied using a two-frequency acoustic apparatus. First, the threshold amplitude of resonant coupling between the volume and axisymmetric shape oscillations is measured for gas bubbles in the shape modes, n=3-6, and for vapor bubbles in the modes, n=4 and 5, where n is the mode number. The result qualitatively agrees with a theoretical prediction based on a phase-space analysis. Secondly, the efficiency of two coupling conditions, two-one (2:1) and one-one (1:1) resonant conditions is compared for the n=4 and 5 modes. The result of the comparison can be generalized as follows: When n is an even number, the (1:1) coupling condition has better energy transfer efficiency than (2:1). The relationship reverses when n is an odd number, i.e., the (2:1) coupling condition has better energy transfer efficiency than (1:1). (C) 2000 American Institute of Physics. [S1070-6631(00)00202-6]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ohsaka, K (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 2 Z9 2 U1 1 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD FEB PY 2000 VL 12 IS 2 BP 283 EP 288 DI 10.1063/1.870306 PG 6 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 271MV UT WOS:000084598800007 ER PT J AU Cockell, CS AF Cockell, CS TI The ultraviolet history of the terrestrial planets - implications for biological evolution SO PLANETARY AND SPACE SCIENCE LA English DT Article ID CARBON-DIOXIDE CONCENTRATIONS; SOLAR ULTRAVIOLET; UV-RADIATION; B RADIATION; EARLY EARTH; SUPERNOVA EXPLOSIONS; YOUNG SUN; ATMOSPHERE; OZONE; MARS AB A radiative transfer model is employed to investigate the comparative surface ultraviolet (UV) radiation histories of Earth, Mars and Venus from 4.5 Ga to the present and thus their comparative theoretical photobiological histories. Earth probably began with a period of higher ultraviolet radiation fluxes during the anoxic Archean. During the early Proterozoic UV fluxes declined as oxygen partial pressures and thus ozone column abundance rose, but the ozone column became subject to stochastic depletion events caused principally by impact events and possibly large-scale volcanism and less frequently, close cosmic events such as supernovae. In contrast Mars has been subject to a history dominated by a slow increase in solar luminosity and a reduction in partial pressures of CO2, both of which have resulted in an increase in UV flux. The UV radiation history of Venus has been dominated by the greenhouse effect through which high partial pressures of CO2 made the surface UV radiation environment clement. These distinct histories influence the potential comparative evolutionary photobiology of the three planets. On Earth, life transitioned from the Archean, when tolerance to UV radiation, particularly for exposed organisms, must have been high to a more photobiologically clement era. In this latter era the predominant evolutionary selection pressure is one that allows for tolerance of sudden and unpredictable increases in UVB radiation above seasonal and diurnal maxima caused by exogenous perturbation of the ozone column. In the case of Mars, the UV radiation flux has increased over time. Today the biologically effective irradiances to DNA are not considerably different from those that are calculated for Archean Earth. If the planet suffered an atmospheric collapse then it may have been subject to an ultraviolet crisis at some point in its past when DNA-weighted irradiance would have increased three to five-fold. Venus transitioned into a photobiologically clement era soon after late bombardment. The lifeless surfaces of Mars and Venus, when in the former case DNA-weighted irradiances are not much greater than Archean Earth and in the latter case, insignificant, are testament to the unimportance of UV radiation as an evolutionary selection pressure when other physical factors, particularly lack of liquid water, become limiting to life. Understanding the comparative evolutionary differences in surface UV flux of the terrestrial planets can help us understand the influence, and lack of influence, of UV radiation in determining their suitability as abodes for life at different stages in their past. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP British Antarctic Survey, Cambridge CB3 0ET, England. EM cockell@mail.arc.nasa.gov NR 89 TC 77 Z9 80 U1 2 U2 29 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD FEB-MAR PY 2000 VL 48 IS 2-3 BP 203 EP 214 DI 10.1016/S0032-0633(99)00087-2 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 290FE UT WOS:000085665000009 ER PT J AU Allison, M McEwen, M AF Allison, M McEwen, M TI A post-Pathfinder evaluation of areocentric solar coordinates with improved timing recipes for Mars seasonal/diurnal climate studies SO PLANETARY AND SPACE SCIENCE LA English DT Article ID PRECESSION; FORMULAS; TIME AB The accurate determination of the Mars pole vector derived from Pathfinder and Viking Lander radio data (Folkner et al., 1997. Science 278, 1749-1752), together with the VSOP87 representation of planetary orbits (Bretagnon and Francou, 1988. Astron. Astrophys. 202, 209-315), have been applied to a new evaluation of the right ascension of the "Fictitious Mean Sun" (FMS) at Mars. With Delta t(J2000) the elapsed time in days from the J2000 epoch (JD 2451545.0(TT)), alpha(FMs)=270 degrees.3863 + 0.5240384(degrees/d).Delta t(J2000)-4 x 10(-13)(degrees/d(2)).Delta tJ(2000)(2) represents a best least-squares quadratic fit of the FMS, including aberration, to each instance of the four equinox and solstice passages for each of 134 Mars orbits spanning the calendar years 1874-2126, The implied tropical orbit period for Mars, 686.9726(d), closely agrees with the recent evaluations by Suran (1997. Planet. Space Sci. 45, 705-708) and Allison (1997. Geophys. Rev. Lett. 24, 1967-1970). Together with the Pathfinder radio determination of the Mars sidereal rotation, the derived FMS rate corresponds to a mean solar day (or "sol") of 1.02749125(d). The new FMS determination would serve to define the Mean Solar Time at Mars to the nearest tenth-second, according to historical conventions originally established for terrestrial time-keeping, once the Mars prime meridian defined by the crater Airy-0 is determined within inertial space to the same accuracy. For convenient reference to current epochs, 2000 January 06 00:00:00 UTC (=MJD 51549.000(UTC)) corresponds to a coincidence of alpha(FMs) and the rotation angle of the crater Airy-0 measured with respect to the Mars equinox (i.e. "mean solar midnight" on the planet's prime meridian), to within the current uncertainty in the locational definition of the planet's cartographic grid. As a further result of the analysis, the consistently derived Mars obliquity of date is epsilon=25 degrees.192 + 3.45 x 10(-7)(degrees/d).Delta t(J2000). An improved analytic recipe for the calculation of the solar areocentric longitude (Ls) of Mars to an accuracy better than 0 degrees.01 is also provided, accounting for the primary perturbations of Earth, Jupiter, and Venus, which may in turn be applied to an efficient evaluation of Mars Local True Solar Time (LTST) to within the uncertainty of the inertial position of the Mars prime meridian. For specific applications to the data archives for landed Mars spacecraft, simple conversion formulae are given for the determination of the Viking "Local Lander Time" and the Pathfinder "Local True Solar Time" in terms of the terrestrial calendar date and UTC. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Astron, New York, NY 10027 USA. RP Allison, M (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 54 TC 29 Z9 29 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD FEB-MAR PY 2000 VL 48 IS 2-3 BP 215 EP 235 DI 10.1016/S0032-0633(99)00092-6 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 290FE UT WOS:000085665000010 ER PT J AU McCandless, JW Ellis, SR Adelstein, BD AF McCandless, JW Ellis, SR Adelstein, BD TI Localization of a time-delayed, monocular virtual object superimposed on a real environment SO PRESENCE-TELEOPERATORS AND VIRTUAL ENVIRONMENTS LA English DT Article ID ABSOLUTE MOTION PARALLAX; DEPTH-PERCEPTION; EGOCENTRIC DISTANCE; PERFORMANCE; CUE AB Observers adjusted a pointer to match the depicted distance of a monocular virtual object viewed in a see-through, head-mounted display. Distance information was available through motion parallax produced as the observers rocked side to side. The apparent stability of the virtual object was impaired by a time delay between the observers' head motions and the corresponding change in the object position on the display. Localizations were made for four time delays (31 ms, 64 ms, 131 ms, and 197 ms) and three depicted distances (75 cm, 95 cm, and 113 cm). The errors in localizations increased systematically with time delay and depicted distance. A model of the results shows that the judgment error and lateral projected position of the virtual object are each linearly related to time delay. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ Fdn, NASA, Ames Res Ctr, Moffett Field, CA USA. RP Ellis, SR (reprint author), NASA, Ames Res Ctr, MS 262-2, Moffett Field, CA 94035 USA. NR 27 TC 10 Z9 10 U1 0 U2 0 PU M I T PRESS PI CAMBRIDGE PA FIVE CAMBRIDGE CENTER, CAMBRIDGE, MA 02142 USA SN 1054-7460 J9 PRESENCE-TELEOP VIRT JI Presence-Teleoper. Virtual Env. PD FEB PY 2000 VL 9 IS 1 BP 15 EP 24 DI 10.1162/105474600566583 PG 10 WC Computer Science, Cybernetics; Computer Science, Software Engineering SC Computer Science GA 305VN UT WOS:000086561400002 PM 11543296 ER PT J AU Yu, YH AF Yu, YH TI Rotor blade-vortex interaction noise SO PROGRESS IN AEROSPACE SCIENCES LA English DT Review ID REDUCTION AB Blade-vortex interaction noise-generated by helicopter main rotor blades is one of the most severe noise problems and is very important both in military applications and community acceptance of rotorcraft. Research over the decades has substantially improved physical understanding of noise-generating mechanisms, and various design concepts have been investigated to control noise radiation using advanced blade planform shapes and active blade control techniques. The important parameters to control rotor blade-vortex interaction noise and vibration have been identified: blade tip vortex structures and its trajectory, blade aeroelastic deformation, and airloads. Several blade tip design concepts have been investigated for diffusing tip vortices and also for reducing noise. However, these tip shapes have not been able to substantially reduce blade-vortex interaction noise without degradation of rotor performance. Meanwhile, blade root control techniques, such as higher-harmonic pitch control (HHC) and individual blade control (IBC) concepts, have been extensively investigated for noise and vibration reduction. The HHC technique has proved the substantial blade-vortex interaction noise reduction, up to 6 dB, while vibration and low-frequency noise have been increased. Tests with IBC techniques have shown the simultaneous reduction of rotor noise and vibratory loads with 2/rev pitch control inputs. Recently, active blade control concepts with smart structures have been investigated with the emphasis on active blade twist and trailing edge flap. Smart structures technologies are very promising, but further advancements are needed to meet all the requirements of rotorcraft applications in frequency, force, and displacement. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Aeroflight Directorate AFDD, Moffett Field, CA 94035 USA. RP Yu, YH (reprint author), NASA, Ames Res Ctr, Aeroflight Directorate AFDD, Moffett Field, CA 94035 USA. EM yyu@mail.arc.nasa.gov NR 82 TC 31 Z9 40 U1 0 U2 12 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0376-0421 J9 PROG AEROSP SCI JI Prog. Aeosp. Sci. PD FEB PY 2000 VL 36 IS 2 BP 97 EP 115 DI 10.1016/S0376-0421(99)00012-3 PG 19 WC Engineering, Aerospace SC Engineering GA 307ZZ UT WOS:000086685200001 ER PT J AU Katz, R Cucinotta, FA AF Katz, R Cucinotta, FA TI Track theory predictions for single-hit cell survival SO RADIATION RESEARCH LA English DT Meeting Abstract C1 Univ Nebraska, Lincoln, NE 68588 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 5 TC 4 Z9 4 U1 0 U2 0 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD FEB PY 2000 VL 153 IS 2 BP 225 EP 226 PG 2 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 280BK UT WOS:000085082000019 ER PT J AU Cerf, VG AF Cerf, VG TI The network of networks in space SO RECHERCHE LA French DT Article RP Cerf, VG (reprint author), NASA, JPL, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC ED SCIENTIFIQUES PI PARIS 06 PA 57 RUE DE SEINE, 75280 PARIS 06, FRANCE SN 0029-5671 J9 RECHERCHE JI Recherche PD FEB PY 2000 IS 328 BP 58 EP 60 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 284KH UT WOS:000085331200014 ER PT J AU Choudhury, BJ AF Choudhury, BJ TI Evaluation of a model adaptable to satellite data for estimating daily gross photosynthesis SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID LEAF NITROGEN DISTRIBUTION; HUBBARD BROOK ECOSYSTEM; CANOPY PHOTOSYNTHESIS; USE EFFICIENCY; CARBON GAIN; RADIATION; CLIMATE; DIFFUSE; LIGHT; STAND AB A model for instantaneous gross canopy photosynthesis, considering sunlit and shaded leaves, variation of maximum rate of leaf photosynthesis within the canopy, and a solution of the radiative transfer equation for propagation of direct and diffuse photosynthetically active radiation, is numerically integrated in space (angular variation of radiances and depth within the canopy) and time (diurnal cycle) to obtain daily total photosynthesis for varied incident irradiances and leaf and canopy characteristics. These numerical results are used to evaluate an analytic model for daily photosynthesis that requires daily total irradiance, recognizing that readily available global satellite data provide daily total irradiance rather than diurnal values of direct and diffuse irradiances. The analytic model is derived by considering the light response function for leaf photosynthesis to be a rectangular hyperbola. The evaluation was done by using field observations for 27 canopies representing four cultivated and seven uncultivated species and having a leaf area index between 0.6 and 5.9. The evaluation gives a mean maximum uncertainty of 32% for the analytic equation. The magnitude of uncertainty can be reduced by knowing the diffuse fraction of incident radiation. Published by Elsevier Science Inc., 2000. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Hydrol Sci Branch, Greenbelt, MD 20771 USA. RP Choudhury, BJ (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Hydrol Sci Branch, Greenbelt, MD 20771 USA. NR 33 TC 3 Z9 3 U1 1 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD FEB PY 2000 VL 71 IS 2 BP 133 EP 140 DI 10.1016/S0034-4257(99)00062-0 PG 8 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 281BU UT WOS:000085138900002 ER PT J AU Johnson, TV AF Johnson, TV TI The Galileo mission to Jupiter and its moons SO SCIENTIFIC AMERICAN LA English DT Article C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnson, TV (reprint author), Jet Prop Lab, Pasadena, CA 91109 USA. NR 5 TC 2 Z9 2 U1 1 U2 4 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 USA SN 0036-8733 J9 SCI AM JI Sci.Am. PD FEB PY 2000 VL 282 IS 2 BP 40 EP 49 PG 10 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 277UJ UT WOS:000084951700022 PM 10710785 ER PT J AU Hagyard, MJ Adams, ML Smith, JE West, EA AF Hagyard, MJ Adams, ML Smith, JE West, EA TI Effects of Faraday rotation observed in filter magnetograph data SO SOLAR PHYSICS LA English DT Article ID VECTOR MAGNETIC-FIELDS AB In this paper we analyze the effects of Faraday rotation on the azimuth of a transverse magnetic field as determined from the linear polarization in the inverse Zeeman effect. Observations of a simple sunspot were obtained with the Marshall Space Flight Center's vector magnetograph over the wavelength interval of 170 m Angstrom redward of line center of the Fe i 5250.22 Angstrom spectral line to 170 m Angstrom to the blue, in steps of 10 m Angstrom. These data were analyzed to produce the variation of the azimuth as a function of wavelength at each pixel over the field of view of the sunspot. At selected locations in the sunspot, curves of the observed variation of azimuth with wavelength were compared with model calculations for the azimuth at each wavelength as derived from the inverse Zeeman effect modified by Faraday rotation. From these comparisons we derived the maximum amount of rotation as functions of both the magnitude and inclination of the sunspot's field. These results show that Faraday rotation of the azimuth will be a significant problem in observations taken near the center of a spectral line for fields as low as 1200 G and inclinations of the field in the range 20-80 deg. Conversely, they show that measurements taken in the wing of a spectral line are relatively free of the effects of Faraday rotation. C1 NASA, Dept Space Sci, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP NASA, Dept Space Sci, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 9 TC 12 Z9 12 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 EI 1573-093X J9 SOL PHYS JI Sol. Phys. PD FEB PY 2000 VL 191 IS 2 BP 309 EP 324 DI 10.1023/A:1005252108523 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 316DC UT WOS:000087151500007 ER PT J AU Launius, RD AF Launius, RD TI The historical dimension of space exploration: reflections and possibilities SO SPACE POLICY LA English DT Review ID SHUTTLE; DECISION; NASA C1 NASA, Hist Off, Washington, DC 20546 USA. RP Launius, RD (reprint author), NASA, Hist Off, Code Z, Washington, DC 20546 USA. NR 201 TC 10 Z9 10 U1 2 U2 2 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0265-9646 J9 SPACE POLICY JI Space Policy PD FEB PY 2000 VL 16 IS 1 BP 23 EP 38 DI 10.1016/S0265-9646(99)00055-7 PG 16 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA 298VT UT WOS:000086160700005 ER PT J AU Klimeck, G Bowen, RC Boykin, TB Salazar-Lazaro, C Cwik, TA Stoica, A AF Klimeck, G Bowen, RC Boykin, TB Salazar-Lazaro, C Cwik, TA Stoica, A TI Si tight-binding parameters from genetic algorithm fitting SO SUPERLATTICES AND MICROSTRUCTURES LA English DT Article; Proceedings Paper CT 3rd NASA Workshop on Device Modeling CY AUG 26-27, 1999 CL NASA AMES RES CTR, MOFFETT FIELD, CA SP NASA HO NASA AMES RES CTR DE tight binding; sp3s*; silicon; genetic algorithm; effective mass ID OPTIMIZATION; MODEL AB Quantum mechanical simulations of carrier transport in Si require an accurate model of the complicated Si bandstructure. Tight-binding models are an attractive method of choice since they bear the full electronic structure symmetry within If hem and can discretize a realistic device on an atomic scale. However, tight-binding models are not simple to pa rameterize and characterize. This work addresses two issues: (1) the need for an automated fitting:procedure that maps tight-binding orbital interaction-energies to physical observables such as effective masses and band edges, and (2) the capabilities and accuracy of the nearest and second-nearest neighbor tight-binding sp3s* models with respect to carrier transport in indirect bandgap materials. A genetic algorithm approach is used to fit orbital interaction energies of these tight-binding models in a nine-; and 20-dimensional global optimization problem for Si. A second-nearest neighbor sp3s* parameter set that fits all relevant conduction and valence band properties: with a high degree of accuracy is presented. No such global fit was found for the nearest neighbor sp3s* model and two sets, one heavily weighed for electron properties and the other for hole properties, are presented. Bandstructure properties relevant for electron and hole transport in Si derived from these three sets are compared with the seminal Vogl et al. [Journal of the Physics and Chemistry of Solids 44, 365 (1983)] parameters. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Klimeck, Gerhard/A-1414-2012 OI Klimeck, Gerhard/0000-0001-7128-773X NR 26 TC 81 Z9 81 U1 2 U2 13 PU ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0749-6036 J9 SUPERLATTICE MICROST JI Superlattices Microstruct. PD FEB-MAR PY 2000 VL 27 IS 2-3 BP 77 EP 88 DI 10.1006/spmi.1999.0797 PG 12 WC Physics, Condensed Matter SC Physics GA 294CB UT WOS:000085891400004 ER PT J AU Delaygue, G Masson, V Jouzel, J Koster, RD Healy, RJ AF Delaygue, G Masson, V Jouzel, J Koster, RD Healy, RJ TI The origin of Antarctic precipitation: a modelling approach SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article ID GENERAL-CIRCULATION MODEL; ICE CORE; DEUTERIUM EXCESS; CLIMATE-CHANGE; GCM ANALYSIS; TEMPERATURE; ISOTOPE; GREENLAND; RECORD; CYCLE AB The contribution of different moisture sources to Antarctic precipitation for present-day and glacial conditions is estimated with the NASA/GISS Atmospheric General Circulation Model. Despite its low horizontal resolution (8 degrees x 10 degrees), this model simulates reasonably well the broad features of the observed present-day hydrological cycle. Simulated present-day Antarctic precipitation is dominated throughout the year by moisture from a subtropical/midlatitude band (30 degrees S-60 degrees S). The moisture supplied to a given coastal area of Antarctica originates mostly in the adjacent oceanic basin; closer to the pole, other oceanic basins can also contribute significantly. Replacing the present-day sea surface temperatures (SSTs) and sea ice cover in the GCM with those from the CLIMAP oceanic reconstruction for the last glacial maximum (LGM), greatly increases the simulated latitudinal temperature gradient, with the consequence of slightly enhancing the contribution of low latitude moisture to Antarctic precipitation. It also changes the seasonality of the different contributions and thus their budget, particularly in coastal regions. Because the nature of LGM tropical SSTs is still under debate, Ne performed an additional LGM simulation in which the tropical SSTs are reduced relative to those of CLIMAP. The resulting decrease in the latitudinal gradient brings the relative contributions to Antarctic precipitation more in line with those of the present-day simulation. C1 CEA Saclay, LSCE, F-91191 Gif Sur Yvette, France. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA. CEREGE, F-13545 Aix En Provence 4, France. RP Delaygue, G (reprint author), CEA Saclay, LSCE, Orme Merisiers, F-91191 Gif Sur Yvette, France. RI Koster, Randal/F-5881-2012; Masson-Delmotte, Valerie/G-1995-2011; Healy, Richard/J-9214-2015 OI Koster, Randal/0000-0001-6418-6383; Masson-Delmotte, Valerie/0000-0001-8296-381X; Healy, Richard/0000-0002-5098-8921 NR 47 TC 72 Z9 75 U1 0 U2 8 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD FEB PY 2000 VL 52 IS 1 BP 19 EP 36 DI 10.1034/j.1600-0889.2000.00951.x PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286FH UT WOS:000085432600002 ER PT J AU Hu, Y Stamnes, K AF Hu, Y Stamnes, K TI Climate sensitivity to cloud optical properties SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article ID EARTH RADIATION BUDGET; GENERAL-CIRCULATION MODEL; CONVECTIVE MODEL; WATER-CONTENT; FEEDBACK; SURFACE; PARAMETERIZATION; MICROPHYSICS; TEMPERATURE; AEROSOLS AB A radiative-convective model was developed to investigate the sensitivity of climate to cloud optical properties and the related feedback processes. This model demonstrates that the Earth's surface temperature increases with cloud optical depth when the clouds are very thin but decreases with cloud optical depth when the cloud shortwave (solar) radiative forcing is larger than the cloud longwave (terrestrial) radiative forcing. When clouds are included in the model, the magnitude of the greenhouse effect due to a doubling of the CO2 concentration varies with the cloud optical depth: the thicker the clouds, the weaker the greenhouse warming. In addition, a small variation in the cloud droplet size has a larger impact on the equilibrium state temperature in the lower atmosphere than the warming caused by a doubling of the CO2 concentration: a 2% increase in the average cloud droplet size per degree increase in temperature doubles the warming caused by the doubling of the CO2 concentration. These findings suggest that physically reliable correlations between the cloud droplet size and macrophysical meteorological variables such as temperature, wind and water vapor fields are needed on a global climate scale to assess the climate impact of increases in greenhouse gases. C1 Hampton Univ, NASA, LARC, Hampton, VA 23681 USA. Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA. RP Stamnes, K (reprint author), Stevens Inst Technol, Hoboken, NJ 07030 USA. RI Hu, Yongxiang/K-4426-2012 NR 42 TC 9 Z9 9 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD FEB PY 2000 VL 52 IS 1 BP 81 EP 93 DI 10.1034/j.1600-0889.2000.00993.x PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 286FH UT WOS:000085432600007 ER PT J AU Yamada, T AF Yamada, T TI Analysis of submicron carbon nanotube field-effect transistors SO APPLIED PHYSICS LETTERS LA English DT Article ID SINGLE-WALL AB A theoretical analysis of carbon nanotube based field-effect transistors fabricated by two different groups [Tans , Nature (London) 393, 49 (1998); Martel , Appl. Phys. Lett. 73, 2447 (1998)] is presented. The metal (electrode)-semiconductor (nanotube) contact influences subthreshold channel conductance versus gate voltage V-G, such that the occurrence of a kink depends on the transport mechanism across this contact. Saturation in the turn-on drain current I-D vs V-G seen in experiments reflects the nanotube state density. Saturationless I-D versus drain voltage V-D indicates transport in the weak-localization regime in the absence of carrier-carrier scattering so that pinch-off cannot occur. To compensate for saturationless I-D(V-D) in digital applications, nanotube transistors need to be designed to maximize their transconductance. (C) 2000 American Institute of Physics. [S0003-6951(00)01505-9]. C1 NASA, Ames Res Ctr, MRJ, Moffett Field, CA 94035 USA. RP Yamada, T (reprint author), NASA, Ames Res Ctr, MRJ, T27A-1, Moffett Field, CA 94035 USA. RI Yamada, Toshishige/E-7834-2012 OI Yamada, Toshishige/0000-0001-7145-9212 NR 15 TC 22 Z9 22 U1 1 U2 37 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JAN 31 PY 2000 VL 76 IS 5 BP 628 EP 630 DI 10.1063/1.125840 PG 3 WC Physics, Applied SC Physics GA 277NB UT WOS:000084938700036 ER PT J AU Cowan, TE Hunt, AW Phillips, TW Wilks, SC Perry, MD Brown, C Fountain, W Hatchett, S Johnson, J Key, MH Parnell, T Pennington, DM Snavely, RA Takahashi, Y AF Cowan, TE Hunt, AW Phillips, TW Wilks, SC Perry, MD Brown, C Fountain, W Hatchett, S Johnson, J Key, MH Parnell, T Pennington, DM Snavely, RA Takahashi, Y TI Photonuclear fission from high energy electrons from ultraintense laser-solid interactions SO PHYSICAL REVIEW LETTERS LA English DT Article ID HOT-ELECTRONS; PLASMA; ACCELERATION; BREAKING; PULSE AB A new regime of laser-matter interactions in which the quiver motion of plasma electrons is fully relativistic, with energies extending well above the threshold for nuclear processes, is studied using a petawatt laser system. In solid target experiments with focused intensities exceeding 10(20) W/cm(2), high energy electron generation, hard bremsstrahlung, and nuclear phenomena have been observed. We report here a quantitative comparison of the high energy electrons and the bremsstrahlung spectrum, as measured by photonuclear reaction yields, including the photoinduced fission of U-238. C1 Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. Univ Alabama, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Space Res Assoc, Huntsville, AL 35806 USA. Harvard Univ, Cambridge, MA 02138 USA. RP Cowan, TE (reprint author), Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. RI Cowan, Thomas/A-8713-2011 OI Cowan, Thomas/0000-0002-5845-000X NR 26 TC 193 Z9 201 U1 0 U2 7 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD JAN 31 PY 2000 VL 84 IS 5 BP 903 EP 906 DI 10.1103/PhysRevLett.84.903 PG 4 WC Physics, Multidisciplinary SC Physics GA 278TU UT WOS:000085005700027 ER PT J AU Bozzolo, G Noebe, RD Garces, JE AF Bozzolo, G Noebe, RD Garces, JE TI Atomistic modeling of the site occupancies of Ti and Cu in NiAl SO SCRIPTA MATERIALIA LA English DT Article DE computer simulation; intermetallic; structural behavior; quantum approximate method; defect theory and modeling C1 Ohio Aerosp Inst, Cleveland, OH 44142 USA. NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. Ctr Atom Bariloche, RA-8400 Bariloche, Rio Negro, Argentina. RP Bozzolo, G (reprint author), Ohio Aerosp Inst, 22800 Cedar Point Rd, Cleveland, OH 44142 USA. NR 4 TC 12 Z9 14 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1359-6462 J9 SCRIPTA MATER JI Scr. Mater. PD JAN 31 PY 2000 VL 42 IS 4 BP 403 EP 408 DI 10.1016/S1359-6462(99)00364-4 PG 6 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 286FA UT WOS:000085431900014 ER PT J AU Bonne, GP Stimpfle, RM Cohen, RC Voss, PB Perkins, KK Anderson, JG Salawitch, RJ Elkins, JW Dutton, GS Jucks, KW Toon, GC AF Bonne, GP Stimpfle, RM Cohen, RC Voss, PB Perkins, KK Anderson, JG Salawitch, RJ Elkins, JW Dutton, GS Jucks, KW Toon, GC TI An examination of the inorganic chlorine budget in the lower stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID UPPER TROPOSPHERE; ER-2 AIRCRAFT; CLONO2; SPECTROMETER; HCL; SPECTROSCOPY; ATMOS; PINATUBO; NITROGEN; AEROSOL AB We use the first simultaneous in situ measurements of ClONO2, ClO, and HCl acquired using the NASA ER-2 aircraft during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission to test whether these three compounds quantitatively account for total inorganic chlorine (Cl-y) in the lower stratosphere in 1997. We find (ClO + ClONO2 + HCl)/Cl-y = 0.92 +/- 0.10, where Cl-y is inferred from in situ measurements of organic chlorine source gases. These observations are consistent with our current understanding of the budget and partitioning of Cl-y in the lower stratosphere. We find no evidence in support of missing inorganic chlorine species that compose a significant fraction of Cl-y. We apply the analysis to earlier ER-2 observations dating from 1991 to investigate possible causes of previously observed discrepancies in the inorganic chlorine budget. Using space shuttle, satellite, balloon, and aircraft measurements in combination with ER-2 data, we find that the discrepancy is unlikely to have been caused by missing chlorine species or an error in the photolysis rate of chlorine nitrate. We also find that HCl/Cl-y is not significantly controlled by aerosol surface area density in the lower stratosphere. C1 Elect Power Res Inst, Environm Div, Palo Alto, CA 94304 USA. Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bonne, GP (reprint author), Elect Power Res Inst, Environm Div, 3412 Hillview Ave, Palo Alto, CA 94304 USA. EM gbonne@epri.com; stimpfle@harvard.edu; cohen@cchem.berkeley.edu; p_voss@huarp.harvard.edu; kperkins@huarp.harvard.edu; anderson@huarp.harvard.edu; rjs@caesar.jpl.nasa.gov; jelkins@cmdl.noaa.gov; gdutton@cmdl.noaa.gov; jucks@cfa.harvard.edu; toon@mark4sun.jpl.nasa.gov RI Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Bonne, Gisele/G-3121-2013 OI Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; NR 56 TC 25 Z9 25 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 2000 VL 105 IS D2 BP 1957 EP 1971 DI 10.1029/1999JD900996 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 280DF UT WOS:000085086400007 ER PT J AU Ghan, S Randall, D Xu, KM Cederwall, R Cripe, D Hack, J Iacobellis, S Klein, S Krueger, S Lohmann, U Pedretti, J Robock, A Rotstayn, L Somerville, R Stenchikov, G Sud, Y Walker, G Xie, SC Yio, J Zhang, MH AF Ghan, S Randall, D Xu, KM Cederwall, R Cripe, D Hack, J Iacobellis, S Klein, S Krueger, S Lohmann, U Pedretti, J Robock, A Rotstayn, L Somerville, R Stenchikov, G Sud, Y Walker, G Xie, SC Yio, J Zhang, MH TI A comparison of single column model simulations of summertime midlatitude continental convection SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; LARGE-SCALE MODELS; PLANETARY BOUNDARY-LAYER; COMMUNITY-CLIMATE-MODEL; ICE-CLOUD MICROPHYSICS; CUMULUS PARAMETERIZATION; PHASE MICROPHYSICS; ENSEMBLE MODELS; WATER CLOUDS; SCHEME AB Eleven different single-column models (SCMs) and one cloud ensemble model (CEM) are driven by boundary conditions observed at the Atmospheric Radiation Measurement (ARM) program southern Great Plains site for a 17 day period during the summer of 1995. Comparison of the model simulations reveals common signatures identifiable as products of errors in the boundary conditions. Intermodel differences in the simulated temperature, humidity, cloud, precipitation, and radiative fluxes reflect differences in model resolution or physical parameterizations, although sensitive dependence on initial conditions can also contribute to intermodel differences. All models perform well at times but poorly at others. Although none of the SCM simulations stands out as superior to the others, the simulation by the CEM is in several respects in better agreement with the observations than the simulations by the SCMs. Nudging of the simulated temperature and humidity toward observations generally improves the simulated cloud and radiation fields as well as the simulated temperature and humidity but degrades the precipitation simulation for models with large temperature and humidity biases without nudging. Although some of the intermodel differences have not been explained, others have been identified as model problems that can be or have been corrected as a result of the comparison. C1 Pacific NW Natl Lab, Richland, WA 99352 USA. Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Univ Calif San Diego, Scripps Inst Oceanog, Dept 0224, La Jolla, CA 92093 USA. Geophys Fluid Dynam Lab, Princeton, NJ 08542 USA. Univ Utah, Dept Meteorol, Salt Lake City, UT 84112 USA. Dalhousie Univ, Dept Phys & Oceanog, Halifax, NS, Canada. Rutgers State Univ, Dept Environm Sci, New Brunswick, NJ USA. CSIRO, Aspendale, Vic 3195, Australia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SUNY Stony Brook, Inst Terr & Planetary Atmospheres, Stony Brook, NY 11794 USA. RP Ghan, S (reprint author), Pacific NW Natl Lab, Richland, WA 99352 USA. EM steve.ghan@pnl.gov RI Xu, Kuan-Man/B-7557-2013; Georgiy, Stenchikov/J-8569-2013; Rotstayn, Leon/A-1756-2012; Xie, Shaocheng/D-2207-2013; Robock, Alan/B-6385-2016; Ghan, Steven/H-4301-2011; Randall, David/E-6113-2011; Klein, Stephen/H-4337-2016; Lohmann, Ulrike/B-6153-2009 OI Robock, Alan/0000-0002-6319-5656; Xu, Kuan-Man/0000-0001-7851-2629; Rotstayn, Leon/0000-0002-2385-4223; Xie, Shaocheng/0000-0001-8931-5145; Ghan, Steven/0000-0001-8355-8699; Randall, David/0000-0001-6935-4112; Klein, Stephen/0000-0002-5476-858X; Lohmann, Ulrike/0000-0001-8885-3785 NR 80 TC 81 Z9 85 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 2000 VL 105 IS D2 BP 2091 EP 2124 DI 10.1029/1999JD900971 PG 34 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 280DF UT WOS:000085086400016 ER PT J AU Lakshmi, V Susskind, J AF Lakshmi, V Susskind, J TI Comparison of TOVS-derived land surface variables with ground observations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AIR-TEMPERATURE; HAPEX-SAHEL; FIFE; SATELLITE; SKIN; DIRECTIONS; GRASSLAND; CLIMATE; DATASET; BOREAS AB The Tires Operational Vertical Sounder (TOVS) Pathfinder Path A retrieved surface skin temperature, surface air temperatures, and surface specific humidity are compared with data obtained from three large-scale field campaigns: the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE), the Hydrologic Atmospheric Pilot Experiment (HAPEX) in the Sahel, and the Boreal Ecosystem-Atmosphere Study (BOREAS). The long-term estimates of surface skin temperatures, surface air temperatures, and surface vapor pressure were unbiased, and the standard deviations of the errors were about 4 degrees C, 3.5 degrees C, and 3.5 mbar, respectively. The monthly mean variables obtained from the TOVS data at four times of the day (corresponding to the AM and PM overpass for each of two satellites) exhibited realistic diurnal and seasonal cycles when compared with corresponding ground observations. C1 Univ S Carolina, Dept Geol Sci, Columbia, SC 29208 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Lakshmi, V (reprint author), Univ S Carolina, Dept Geol Sci, Columbia, SC 29208 USA. EM vlakshmi@geol.sc.edu RI Lakshmi, Venkat/I-3078-2016 OI Lakshmi, Venkat/0000-0001-7431-9004 NR 20 TC 22 Z9 23 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 2000 VL 105 IS D2 BP 2179 EP 2190 DI 10.1029/1999JD900921 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 280DF UT WOS:000085086400021 ER PT J AU Lockard, DP AF Lockard, DP TI An efficient, two-dimensional implementation of The Ffowcs Williams and Hawkings equation SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID COMPUTATIONAL AEROACOUSTICS; FORMULATION; RADIATION AB This paper describes a two-dimensional formulation of the Ffowcs Williams and Hawkings equation in the frequency domain. By assuming subsonic rectilinear motion of all acoustic sources, an efficient and easily implemented form of the equation is developed. This method is capable of predicting the farfield noise from non-linear nearfield flow quantities. The ability to use non-linear input data is a clear advantage over Kirchhoff methods, that are only valid in regions where the linear wave equation accurately describes the flow. Several example problems are used to demonstrate that the new method performs well for problems with a mean flow, tonal and broadband noise signatures, and non-linear near fields. In most practical acoustic problems, three-dimensionality is important and should not be neglected. For these real-world applications, two-dimensional solutions can be used to guide and augment full three-dimensional calculations, but not replace them. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Lockard, DP (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 23 TC 45 Z9 50 U1 1 U2 4 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD JAN 27 PY 2000 VL 229 IS 4 BP 897 EP 911 DI 10.1006/jsvi.1999.2522 PG 15 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 278VY UT WOS:000085010700009 ER PT J AU Gawronski, W AF Gawronski, W TI Modal actuators and sensors SO JOURNAL OF SOUND AND VIBRATION LA English DT Letter ID FLEXIBLE STRUCTURES; PLACEMENT C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gawronski, W (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 35 Z9 35 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD JAN 27 PY 2000 VL 229 IS 4 BP 1013 EP 1022 DI 10.1006/jsvi.1999.2499 PG 10 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 278VY UT WOS:000085010700016 ER PT J AU Pavarino, LF Widlund, OB AF Pavarino, LF Widlund, OB TI Iterative substructuring methods for spectral element discretizations of elliptic systems - I: Compressible linear elasticity SO SIAM JOURNAL ON NUMERICAL ANALYSIS LA English DT Article DE linear elasticity; spectral element methods; preconditioned iterative methods; substructuring; Gauss-Lobatto-Legendre quadrature ID 3 DIMENSIONS; P-VERSION; DOMAIN DECOMPOSITION; MULTIGRID METHOD; SCHWARZ METHODS; SOLID MECHANICS; ALGORITHM; APPROXIMATION AB An iterative substructuring method for the system of linear elasticity in three dimensions is introduced and analyzed. The pure displacement formulation for compressible materials is discretized with the spectral element method. The resulting stiffness matrix is symmetric and positive definite. The proposed method provides a domain decomposition preconditioner constructed from local solvers for the interior of each element and for each face of the elements and a coarse, global solver related to the wire basket of the elements. As in the scalar case, the condition number of the preconditioned operator is independent of the number of spectral elements and grows as the square of the logarithm of the spectral degree. C1 Univ Milan, Dipartimento Matemat, I-20133 Milan, Italy. NASA, Inst Comp Applicat Sci & Engn, Langley Res Ctr, Hampton, VA 23681 USA. NYU, Courant Inst Math Sci, New York, NY 10012 USA. RP Pavarino, LF (reprint author), Univ Milan, Dipartimento Matemat, Via Saldini 50, I-20133 Milan, Italy. EM pavarino@dragon.ian.pv.cnr.it; widlund@cs.nyu.edu RI Pavarino, Luca/A-7631-2011 NR 40 TC 16 Z9 16 U1 0 U2 1 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 0036-1429 J9 SIAM J NUMER ANAL JI SIAM J. Numer. Anal. PD JAN 26 PY 2000 VL 37 IS 2 BP 353 EP 374 PG 22 WC Mathematics, Applied SC Mathematics GA 281JX UT WOS:000085156200001 ER PT J AU Pavarino, LF Widlund, OB AF Pavarino, LF Widlund, OB TI Iterative substructuring methods for spectral element discretizations of elliptic systems. II: Mixed methods for linear elasticity and Stokes flow SO SIAM JOURNAL ON NUMERICAL ANALYSIS LA English DT Article DE linear elasticity; Stokes problem; spectral element methods; mixed methods; preconditioned iterative methods; substructuring; Gauss-Lobatto-Legendre quadrature ID SADDLE-POINT PROBLEMS; 3 DIMENSIONS; MULTIGRID METHOD; PENALTY TERM; PRECONDITIONERS; ALGORITHMS; EQUATIONS AB Iterative substructuring methods are introduced and analyzed for saddle point problems with a penalty term. Two examples of saddle point problems are considered: The mixed formulation of the linear elasticity system and the generalized Stokes system in three dimensions. These problems are discretized with spectral element methods. The resulting stiffness matrices are symmetric and indefinite. The interior unknowns of each element are first implicitly eliminated by using exact local solvers. The resulting saddle point Schur complement is solved with a Krylov space method with block preconditioners. The velocity block can be approximated by a domain decomposition method, e.g., of wire basket type, which is constructed from a local solver for each face of the elements, and a coarse solver related to the wire basket of the elements. The condition number of the preconditioned operator is independent of the number of spectral elements and is bounded from above by the product of the square of the logarithm of the spectral degree and the inverse of the discrete inf-sup constant of the problem. C1 Univ Milan, Dipartimento Matemat, I-20133 Milan, Italy. NASA, Inst Comp Applicat Sci & Engn, Langley Res Ctr, Hampton, VA 23681 USA. NYU, Courant Inst Math Sci, New York, NY 10012 USA. RP Pavarino, LF (reprint author), Univ Milan, Dipartimento Matemat, Via Saldini 50, I-20133 Milan, Italy. EM pavarino@dragon.ian.pv.cnr.it; widlund@cs.nyu.edu RI Pavarino, Luca/A-7631-2011 NR 46 TC 28 Z9 28 U1 0 U2 3 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 0036-1429 J9 SIAM J NUMER ANAL JI SIAM J. Numer. Anal. PD JAN 26 PY 2000 VL 37 IS 2 BP 375 EP 402 DI 10.1137/S0036142998333092 PG 28 WC Mathematics, Applied SC Mathematics GA 281JX UT WOS:000085156200002 ER PT J AU Johnson, RE Schnellenberger, D Wong, MC AF Johnson, RE Schnellenberger, D Wong, MC TI The sputtering of an oxygen thermosphere by energetic O+ SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ION PRECIPITATION; SPATIAL DISTRIBUTIONS; MARTIAN ATMOSPHERE; NITROGEN-ATOMS; MASS-LOSS; MARS; EUROPA; IMPACT; CONSEQUENCES; DEPOSITION AB Using two Monte Carlo models, we have calculated the ejection of O atoms from an atomic oxygen thermosphere which is bombarded by energetic O+. In these calculations, incident oxygen ions strike atmospheric O, heating the atmosphere and setting O atoms on escape trajectories. For those ion fluxes most relevant to atmospheric sputtering at Mars, the full Monte Carlo model (DSMC model) is found to give the same sputtering yield as the Monte Carlo model in which the atmospheric structure is ignored and only the energetic atoms are tracked. In both models the sputtering yield is reduced by the electronic energy loss by the ions. The yield depends weakly on the details of the interaction potential if the relative amounts of forwardscattering to backscattering are realistic. The ejected atom energy spectra for the mean incident angle 55 degrees are shown to be harder than the standard collision cascade distribution, close to the so-called "incomplete cascade distribution." Yields for grazing incidence and for a thin atmosphere such as Europa's are given, and the analytic models used earlier are tested. Because the isotope ratios at Mars are likely to have been determined by atmospheric sputtering, Ar and Ne are included as constituents to verify the analytic models for the sputtering of trace species. The yields calculated here for an atomic O thermosphere can be used to estimate the sputtering of an atmosphere having molecules at the exobase. For Mars, ignoring feedback processes and using the ion fluxes listed by Johnson and Luhmann [1998], the loss is similar to 0.45 bar, of which similar to 0.15 bar is CO2 with the largest uncertainty for atmospheric loss being the incident ion flux. C1 Univ Virginia, Dept Engn Phys, Charlottesville, VA 22903 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. AER Corp, Cambridge, MA USA. RP Johnson, RE (reprint author), Univ Virginia, Dept Engn Phys, Thornton Hall, Charlottesville, VA 22903 USA. NR 51 TC 42 Z9 43 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2000 VL 105 IS E1 BP 1659 EP 1670 DI 10.1029/1999JE001058 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 278UB UT WOS:000085006400003 ER PT J AU Pesnell, WD Grebowsky, J AF Pesnell, WD Grebowsky, J TI Meteoric magnesium ions in the Martian atmosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID RADIO OCCULTATION METHODS; NIGHTSIDE IONOSPHERE; DAYSIDE IONOSPHERE; ACCRETION RATE; METAL-IONS; MARS; DUST; CHEMISTRY; VENUS; MODEL AB From a thorough modeling of the altitude profile of meteoric ionization in the Martian atmosphere we deduce that a persistent layer of magnesium ions should exist around an altitude of 70 km. On the basis of the estimated meteoroid mass flux density, a peak ion density of similar to 10(4) ions cm(3) is predicted. Allowing for the uncertainties in all of the model parameters, this value is probably within an order of magnitude of the collect density. Of these parameters, the peak density is most sensitive to the meteoroid mass flux density which determines the source function for Mg from the ablating meteoroids. Unlike the terrestrial case, where the metallic ion production is dominated by charge-exchange of the deposited neutral Me with the ambient ions, Mg-4 in the Martian atmosphere is produced predominantly by photoionization. The low ultraviolet absorption of the Martian atmosphere makes Mars an excellent laboratory in which to study meteoric ablation. Resonance lines in the ultraviolet that cannot be seen in the spectra of terrestrial meteors may be visible to a surface observatory in the Martian highlands. C1 Nomad Res Inc, Bowie, MD 20716 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Pesnell, WD (reprint author), Nomad Res Inc, 2804 Nomad Court, Bowie, MD 20716 USA. RI Pesnell, William/D-1062-2012; Grebowsky, Joseph/I-7185-2013 OI Pesnell, William/0000-0002-8306-2500; NR 63 TC 49 Z9 49 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2000 VL 105 IS E1 BP 1695 EP 1707 DI 10.1029/1999JE001115 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 278UB UT WOS:000085006400006 ER PT J AU Golombek, M AF Golombek, M TI Introduction to the special section: Results from Mars Pathfinder Part 2 SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Editorial Material C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Golombek, M (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-501,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2000 VL 105 IS E1 BP 1719 EP 1719 DI 10.1029/1999JE001198 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 278UB UT WOS:000085006400009 ER PT J AU Bell, JF McSween, HY Crisp, JA Morris, RV Murchie, SL Bridges, NT Johnson, JR Britt, DT Golombek, MP Moore, HJ Ghosh, A Bishop, JL Anderson, RC Bruckner, J Economou, T Greenwood, JP Gunnlaugsson, HP Hargraves, RM Hviid, S Knudsen, JM Madsen, MB Reid, R Rieder, R Soderblom, L AF Bell, JF McSween, HY Crisp, JA Morris, RV Murchie, SL Bridges, NT Johnson, JR Britt, DT Golombek, MP Moore, HJ Ghosh, A Bishop, JL Anderson, RC Bruckner, J Economou, T Greenwood, JP Gunnlaugsson, HP Hargraves, RM Hviid, S Knudsen, JM Madsen, MB Reid, R Rieder, R Soderblom, L TI Mineralogic and compositional properties of Martian soil and dust: Results from Mars Pathfinder SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID VIKING BIOLOGY EXPERIMENTS; HAWAIIAN PALAGONITIC SOIL; HUBBLE-SPACE-TELESCOPE; MAGNETIC-PROPERTIES; HYDROTHERMAL ALTERATION; REFLECTANCE SPECTRA; IRON-OXIDES; IMAGING SPECTROSCOPY; REFLECTIVITY SPECTRA; CHEMICAL-COMPOSITION AB Mars Pathfinder obtained multispectral, elemental, magnetic, and physical measurements of soil and dust at the Sagan Memorial Station during the course of its 83 sol mission. We describe initial results from these measurements, concentrating on multispectral and elemental data, and use these data, along with previous Viking, SNC meteorite, and telescopic results, to help constrain the origin and evolution of Martian soil and dust. We find that soils and dust can be divided into at least eight distinct spectral units, based on parameterization of Imager for Mars Pathfinder (IMP) 400 to 1000 nm multispectral images. The most distinctive spectral parameters for soils and dust are the reflectivity in the red, the red/blue reflectivity ratio, the near-IR spectral slope, and the strength of the 800 to 1000 nm absorption feature. Most of the Pathfinder spectra are consistent with the presence of poorly crystalline or nanophase ferric oxide(s), sometimes mixed with small but varying degrees of well-crystalline ferric and ferrous phases. Darker soil units appear to be coarser-grained. compacted. and/or mixed with a larger amount of dark ferrous materials relative to bright soils. Nanophase goethite. akaganeite, schwertmannite, and maghemite are leading candidates for the origin of the absorption centered near 900 nm in IMP spectra. The ferrous component in the soil cannot be well-constrained based on IMP data. Alpha proton X-ray spectrometer (APXS) measurements of six soil units show little variability within the landing site and show remarkable overall similarity to the average Viking-derived soil elemental composition. Differences exist between Viking and Pathfinder soils, however, including significantly higher S and Cl abundances and lower Si abundances in Viking soils and the lack of a correlation between Ti and Fe in Pathfinder soils. No significant linear correlations were observed between IMP spectral properties and APXS elemental chemistry. Attempts at constraining the mineralogy of soils and dust using normative calculations involving mixtures of smectites and silicate and oxide minerals did not yield physically acceptable solutions. We attempted to use the Pathfinder results to constrain a number of putative soil and dust formation scenarios, including palagonitization and acid-fog weathering. While the Pathfinder soils cannot be chemically linked to the Pathfinder rocks by palagonitization, this study and McSween er al. [1999] suggest that palagonitic alteration of a Martian basaltic rock, plus mixture with a minor component of locally derived andesitic rock fragments, could be consistent with the observed soil APXS and IMP properties. C1 Cornell Univ, Dept Astron, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. Univ Tennessee, Dept Geol Sci, Knoxville, TN 37996 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. US Geol Survey, Astrogeol Branch, Flagstaff, AZ 86001 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. US Geol Survey, Menlo Park, CA 94025 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Max Planck Inst Chem, D-55020 Mainz, Germany. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Copenhagen, Niels Bohr Inst, DK-2100 Copenhagen, Denmark. Princeton Univ, Dept Geosci, Princeton, NJ 08544 USA. RP Bell, JF (reprint author), Cornell Univ, Dept Astron, Ctr Radiophys & Space Res, 402 Space Sci Bldg, Ithaca, NY 14853 USA. RI Madsen, Morten/D-2082-2011; Murchie, Scott/E-8030-2015; Johnson, Jeffrey/F-3972-2015; Bridges, Nathan/D-6341-2016; Crisp, Joy/H-8287-2016 OI Madsen, Morten/0000-0001-8909-5111; Murchie, Scott/0000-0002-1616-8751; Crisp, Joy/0000-0002-3202-4416 NR 153 TC 168 Z9 169 U1 5 U2 48 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2000 VL 105 IS E1 BP 1721 EP 1755 DI 10.1029/1999JE001060 PG 35 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 278UB UT WOS:000085006400010 ER PT J AU Morris, RV Golden, DC Bell, JF Shelfer, TD Scheinost, AC Hinman, NW Furniss, G Mertzman, SA Bishop, JL Ming, DW Allen, CC Britt, DT AF Morris, RV Golden, DC Bell, JF Shelfer, TD Scheinost, AC Hinman, NW Furniss, G Mertzman, SA Bishop, JL Ming, DW Allen, CC Britt, DT TI Mineralogy, composition, and alteration of Mars Pathfinder rocks and soils: Evidence from multispectral, elemental, and magnetic data on terrestrial analogue, SNC meteorite, and Pathfinder samples SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID ALUMINUM-SUBSTITUTED HEMATITES; HAWAIIAN PALAGONITIC SOIL; IRON-OXIDES; REFLECTANCE SPECTRA; BASALTIC GLASS; MARTIAN SOIL; IMPACT MELT; HYDROTHERMAL ALTERATION; CHEMICAL-COMPOSITION; MU-M AB Major element, multispectral, and magnetic progenies data were obtained at Ares Vallis during the Mars Pathfinder mission. To understand the compositional, mineralogical, and process implications of these data, we obtained major element, mineralogical, and magnetic data for well-crystalline and nanophase ferric minerals, terrestrial analogue samples with known geologic context, and SNC meteorites. Analogue samples include unaltered, palagonitic, and sulfatetic tephra from Mauna Kea Volcano (hydrolytic and acid-sulfate alteration), steam vent material from Kilauea Volcano (hydrolytic alteration), and impactites from Meteor Crater (relithification). Salient results for Mars Pathfinder include: (1) Band depths BD530b and BD600 and the reflectivity ratio R800/R750 are consistent with the dominant ferric mineral being nanophase ferric oxide associated with an unknown amount of H2O and occurring in composite particles along with subordinate amounts of other ferric minerals. Hematite and hematite plus nanophase goethite are most consistent with the data, but maghemite, akaganeite, schwertmannite, and nanophase lepidocrocite are also possible interpretations. Ferric oxides that are consistently not favored by the data as sole alteration products are jarosites and well-crystalline goethite and lepidocrocite. (2) The strength of the ferric adsorption edge (R750/R445) implies the Fe3+/Fe2+ values for Pathfinder rock and soil are within the ranges 0.7-3 and 3-20, respectively. (3) Ferrous silicates are indicated for subsets of Pathfinder rocks and soils. One subset has a band minimum near 930 nm that can attributed to low-Ca pyroxene. Alternatively, the band could be a second manifestation of certain ferric oxides, including nanophase goethite, maghemite, akaganeite, and schwertmannite. Another subset has a negative spectral slope from similar to 800 to 1005 nm which could result from the high-energy wing of a high-Ca pyroxene and/or olivine band, a mixture of bright and dark materials, and, for rocks, thin coatings of bright dust on dark rocks. (4) Chemical data on Pathfinder rocks and soils are consistent with two-component mixtures between an "andesitic" rock with low MgO and SO3 concentrations (soil-free rock) and a global, basaltic soil with high MgO and SO, concentrations (rock-free soil). Pathfinder rock-free soil can be modeled as a chemical mixture of SNC meteorites and the Pathfinder soil-free rock. (5) Pathfinder soil cannot be obtained by chemical alteration of Pathfinder rocks by any of the hydrolytic and acid-sulfate alteration processes we studied. Presumably, global mixing has obscured and possibly erased the elemental signatures of chemical alteration. (6) The strongly magnetic phase in palagonitic and sulfatetic tephra is titanomagnetite and possibly its oxidation product titanomaghemite (Fe-Ti spinels). The saturation magnetization of the tephra samples (0.5-2.0 Am-2/kg) is at or below the low end of the range inferred for Martian dust (4+/-2 Am-2/kg), implying that lithogenic Fe-Ti spinels are a possible candidate for the Martian strongly magnetic phase. (7) The predominantly palagonitic spectral signature and magnetic nature of Martian soil and dust are consistent with glassy precursors with imbedded Fe-Ti spinel particles. Comparison with lunar glass production rates suggests that production of sufficient quantities of glassy materials on Mars by volcanic and impact processes is sufficient to account for these observations. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Space Operat Co, Houston, TX 77058 USA. Cornell Univ, Dept Astron, Ithaca, NY USA. Univ Delaware, Dept Plant & Soil Sci, Newark, DE 19717 USA. Univ Montana, Dept Geol, Missoula, MT 59812 USA. Franklin & Marshall Coll, Dept Geosci, Lancaster, PA 17604 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RP Morris, RV (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RI Scheinost, Andreas/D-2275-2010 NR 219 TC 212 Z9 212 U1 16 U2 64 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2000 VL 105 IS E1 BP 1757 EP 1817 DI 10.1029/1999JE001059 PG 61 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 278UB UT WOS:000085006400011 ER PT J AU Greeley, R Kraft, MD Kuzmin, RO Bridges, NT AF Greeley, R Kraft, MD Kuzmin, RO Bridges, NT TI Mars Pathfinder landing site: Evidence for a change in wind regime from lander and orbiter data SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GLOBAL SURVEYOR; MISSION; STREAKS; CAMERA AB Surface features related to the wind are observed in the vicinity of the Mars Pathfinder (MPF) landing site data from the lander and in data from orbit by the Viking Orbiter and Mars Global Surveyor missions. Features seen from the surface include wind tails associated with small rocks, barchanoid duneforms, ripplelike patterns, and ventifact flutes cut into some rocks. Features seen from orbit include wind tails associated with impact craters, ridges inferred to be duneforms, and modified crater rims interpreted to have been eroded and mantled by windblown material. The orientations of these features show two prevailing directions. One is inferred to represent winds from the northeast, which is consistent with strongest winds predicted by a general circulation model to occur during the Martian northern winter under current conditions. A second wind blowing from the ESE was responsible for modifying the crater rims and cutting some of the ventifacts. The two wind regimes could reflect a change in climate related to Mars' obliquity or some other, unknown factor. Regardless of the cause, the MPF area has been subjected to a complex pattern of winds and supply of small particles, and the original surface formed by sedimentary processes from Tiu and Ares Vallis flooding events has been modified by repeated burial and exhumation. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Russian Acad Sci, Vernadsky Inst, Moscow 117975, Russia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Greeley, R (reprint author), Arizona State Univ, Dept Geol, Box 871404, Tempe, AZ 85287 USA. RI Bridges, Nathan/D-6341-2016 NR 42 TC 30 Z9 30 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2000 VL 105 IS E1 BP 1829 EP 1840 DI 10.1029/1999JE001072 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 278UB UT WOS:000085006400013 ER PT J AU Golombek, MP Bridges, NT AF Golombek, MP Bridges, NT TI Erosion rates on Mars and implications for climate change: Constraints from the Pathfinder landing site SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID IMPACT CRATERS; SURFACE; GEOMORPHOLOGY; DEGRADATION; MORPHOLOGY; CAMERA; SILT AB The observation that the Mars Pathfinder landing site looks very similar to its appearance after it was deposited by catastrophic floods around 1.8-3.5 Ga allows quantitative constraints to be placed on the rate of change of the site since that time. The abundance of erosional features such as an exhumed former soil horizon, sculpted wind tails, ripplelike and other lag deposits, and ventifacts (fluted and grooved rocks) all suggest the site has undergone net deflation or loss of 3-7 cm of material. The presence of barchan dunes and ventifacts argues for erosion by saltating crystalline sand-size particles entrained in the wind. Most ventifacts probably formed soon after the catastrophic flood, which likely introduced a large, fresh supply of sand-size particles distributed across the rocky plain. The strongest winds blew toward the northwest during this time, resulting in the sculpting of ventifacts, deflation of the surface, collections of dunes within Big Crater and other lows, and possibly preferentially eroding small crater rims. The predominant wind direction changed to blow toward the southwest, similar to today. These winds further deflated the surface, completed the deposition of sand-size material in dunes and ultimately trapped these dunes in lows. The erosional features observed by Pathfinder indicate extremely low longterm deflation rates of 0.01-0.04 nm/yr since the end of the Hesperian (1.8-3.5 Ga) similar to less precise rates of <1 nm/yr based on the preservation of craters at the Viking 1 and Pathfinder landing sites. Short-term redistribution rates (deposition and removal) of atmospheric dust at the Pathfinder landing site and preexisting dust and sand at other locations on Mars are up to 10(5) nm/yr, Estimates of erosion rates on Mars show a rapid decrease by 3-6 orders of magnitude from 10(2)-10(4) nm/yr in Noachian terrains (characterized by rimless, flat-floored craters and valley networks) to the exceedingly slow rates (10(-2)-10(-1) nm/yr) operating during the Hesperian and Amazonian. Noachian erosion rates comparable to low continental denudation rates on Earth are consistent with erosion by running water and perhaps a more clement climate. The rapid decrease in erosion rates is consistent with a major climatic change during the Noachian, at the tail end of heavy bombardment, and a cold, dry, desiccating climate similar to today's since that time. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Golombek, MP (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-501,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Bridges, Nathan/D-6341-2016 NR 69 TC 102 Z9 102 U1 3 U2 15 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2000 VL 105 IS E1 BP 1841 EP 1853 DI 10.1029/1999JE001043 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 278UB UT WOS:000085006400014 ER PT J AU Landis, GA Jenkins, PP AF Landis, GA Jenkins, PP TI Measurement of the settling rate of atmospheric dust on Mars by the MAE instrument on Mars Pathfinder SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB fThe Materials Adherence Experiment (MAE) on Pathfinder was designed to measure the rate of dust settling from the Martian atmosphere onto the solar array of the Mars Pathfnder Sojourner Rover. The MAE measurements indicate steady dust accumulation at a rate of about 0.28% per day. This value is consistent with the performance of the lander solar arrays, which decreased in power at an estimated rate of 0.29% per day over the same period. C1 NASA, John Glenn Res Ctr, Ohio Aerosp Inst, Cleveland, OH 44135 USA. RP Landis, GA (reprint author), NASA, John Glenn Res Ctr, Ohio Aerosp Inst, MS 302-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 12 TC 67 Z9 67 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2000 VL 105 IS E1 BP 1855 EP 1857 DI 10.1029/1999JE001029 PG 3 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 278UB UT WOS:000085006400015 ER PT J AU Frlez, E Supek, I Assamagan, KA Bronnimann, C Flugel, T Krause, B Lawrence, DW Mzavia, D Pocanic, D Renker, D Ritt, S Slocum, PL Soic, N AF Frlez, E Supek, I Assamagan, KA Bronnimann, C Flugel, T Krause, B Lawrence, DW Mzavia, D Pocanic, D Renker, D Ritt, S Slocum, PL Soic, N TI Cosmic muon tomography of pure cesium iodide calorimeter crystals SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article DE computed tomography; scintillation detectors; Monte Carlo simulations ID RADIATIVE-CORRECTIONS; BRANCHING RATIO; CSI CRYSTALS; DECAY; SCINTILLATORS AB Scintillation properties of pure CsI crystals used in the shower calorimeter being built for precise determination of the pi(+) --> pi(0)e(+)v(e) decay rate are reported. Seventy-four individual crystals, polished and wrapped in Teflon foil, were examined in a multiwire drift chamber system specially designed for transmission cosmic muon tomography. Critical elements of the apparatus and reconstruction algorithms enabling measurement of spatial detector optical nonuniformities are described. Results are compared with a Monte Carlo simulation of the light response of an ideal detector. The deduced optical nonuniformity contributions to the FWHM energy resolution of the PIBETA CsI calorimeter for the pi(+) --> e(+)v 69.8 MeV positrons and the monoenergetic 70.8 MeV photons were 2.7% and 3.7%, respectively. The upper limit of optical nonuniformity correction to the 69.8 MeV positron low-energy tail between 5 and 55 MeV was + 0.2%, as opposed to the + 0.3% tail contribution for the photon of the equivalent total energy. Imposing the 5 MeV calorimeter veto cut to suppress the electromagnetic losses, GEANT-evaluated positron and photon lineshape tail fractions summed over all above-threshold ADCs were found to be 2.36 +/- 0.05 (stat) +/- 0.20 (sys)% and 4.68 +/- 0.07 (stat) +/- 0.20 (sys)%, respectively. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Virginia, Dept Phys, Charlottesville, VA 22901 USA. Rudjer Boskovic Inst, HR-10000 Zagreb, Croatia. Hampton Univ, Dept Phys, Hampton, VA 23668 USA. Paul Scherrer Inst, CH-5232 Villigen, Switzerland. ETH Zurich, Inst Teilchenphys, CH-8093 Zurich, Switzerland. Deutsch Elektronen Synchrotron, D-22603 Hamburg, Germany. Arizona State Univ, Dept Phys & Astron, Tempe, AZ 85281 USA. Univ Massachusetts, Dept Phys, Amherst, MA 01003 USA. Tbilisi State Univ, Inst High Energy Phys, GE-380086 Tbilisi, Rep of Georgia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Frlez, E (reprint author), Univ Virginia, Dept Phys, Charlottesville, VA 22901 USA. RI Soic, Neven/J-3911-2012; Frlez, Emil/B-6487-2013 NR 27 TC 9 Z9 9 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD JAN 21 PY 2000 VL 440 IS 1 BP 57 EP 85 DI 10.1016/S0168-9002(99)00886-4 PG 29 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 275YM UT WOS:000084847900006 ER PT J AU Surace, JA Sanders, DB Evans, AS AF Surace, JA Sanders, DB Evans, AS TI High-resolution optical/near-infrared imaging of cool ultraluminous infrared galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : interactions; galaxies : star clusters; galaxies : starburst; infrared : galaxies ID INTERACTING GALAXIES; ENERGY-DISTRIBUTIONS; IRAS OBSERVATIONS; STANDARD STARS; SAMPLE; PHOTOMETRY; TRANSFORMATIONS; EVOLUTION; QUASARS; ORIGIN AB We present high spatial resolution (FWHM approximate to 0 ".3-0 ".8) BIHK'-band imaging of a sample of ultraluminous infrared galaxies (L-ir > 10(12) L-circle dot; ULIGs) with "cool" mid-infrared colors (f(25) (mu m)/f(60) (mu m) < 0.2) which select against active galactic nucleus-like (AGN-like) systems, a complementary sample to the "warm" ULIGs of Surace and coworkers. We find that all of the cool ULIGs are either advanced mergers or are premergers with evidence for still-separate nuclei with separations greater than 600 pc. Extended tidal features such as tails and loops as well as clustered star formation are observed in most systems. This extended tidal structure suggests a common progenitor geometry for most of the ULIGs: a plunging disk collision where the disks are highly inclined with respect to each other. The underlying host galaxies have H-band luminosities of 1-2.5L*, very similar to that found in the warm ULIGs. The nuclear regions of these galaxies have morphologies and colors characteristic of a recent burst of star formation mixed with hot dust and mildly extinguished by A(V) = 2-5 mag; only in one case (IRAS 22491-1808) is there evidence for a compact emission region with colors similar to those of an extinguished QSO. Most of the observed star-forming knots appear to have very young (10 Myr) ages based on their optical/near-infrared colors. These star-forming knots are insufficiently luminous to typically provide more than 10% of the high bolometric luminosity of the systems. C1 CALTECH, Ctr Infrared Proc & Anal, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. RP Surace, JA (reprint author), CALTECH, Ctr Infrared Proc & Anal, Jet Prop Lab, MS 100-22, Pasadena, CA 91125 USA. NR 51 TC 103 Z9 103 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 170 EP 188 DI 10.1086/308247 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700019 ER PT J AU Stewart, SG Fanelli, MN Byrd, GG Hill, JK Westpfahl, DJ Cheng, KP O'Connell, RW Roberts, MS Neff, SG Smith, AM Stecher, TP AF Stewart, SG Fanelli, MN Byrd, GG Hill, JK Westpfahl, DJ Cheng, KP O'Connell, RW Roberts, MS Neff, SG Smith, AM Stecher, TP TI Star formation triggering mechanisms in dwarf galaxies: The far-ultraviolet, H alpha, and HI morphology of Holmberg II SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : dwarf; galaxies : ISM; galaxies : individual (DDO 50); stars : formation; ultraviolet : galaxies ID LARGE-MAGELLANIC-CLOUD; IRREGULAR GALAXIES; SURFACE PHOTOMETRY; IMAGING TELESCOPE; SPECTRAL-SYNTHESIS; CONSTELLATION-III; OB ASSOCIATIONS; EMISSION-LINE; REGIONS; GAS AB Far-ultraviolet (FUV), H alpha, and H I observations of dwarf galaxy Holmberg II are used to investigate the means by which star formation propagates in galaxies lacking global internal triggering mechanisms such as spiral density waves. The observations trace the interaction between sites of massive star formation and the neutral and ionized components of the surrounding ISM in this intrinsically simple system. Both local and large-scale triggering mechanisms related to massive star formation are seen, suggesting that feedback from massive stars is a microscopic process operating in all galaxies to a certain degree. The data emphasize the importance of local conditions in regulating star formation from evidence such as massive stars inside ionized shells, compact H II regions surrounding aging clusters, and stars formed in chains of progressing age. Surface brightness profiles show that current activity correlates with the time-averaged level of past star formation at a given radius demonstrating a reliance on local conditions. Large-scale triggering by H I shells is supported by observations of progenitor populations as well as secondary sites of star formation associated with their dense rims. Analysis of the energy available from massive stars inside H I shells indicates that energy deposited into the ISM from supernovae and stellar winds is sufficient to account for the H I morphology. Ages of individual star-forming regions are derived using B, H alpha, and FUV photometry and show both older, diffuse FUV regions and younger, compact H II regions. The distribution of ages is reconciled with the H I morphology, showing a clear preference of young regions for areas of dense H I and old regions for H I voids. Global kinematical properties may also play a role in the star formation process since differences in the rotation characteristics of the neutral gas disk correlate with differences in triggering mechanisms. Large-scale feedback from massive stars is shown to operate in regions that lack differential shear in the gas disk. C1 USN Observ, Washington, DC 20392 USA. Univ N Texas, Dept Phys, Denton, TX 76203 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Hughes STX, Lanham, MD 20706 USA. New Mexico Inst Min & Technol, Dept Phys, Socorro, NM 87801 USA. Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92634 USA. Univ Virginia, Charlottesville, VA 22903 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Stewart, SG (reprint author), USN Observ, 3450 Massachusetts Ave NW, Washington, DC 20392 USA. NR 73 TC 53 Z9 54 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 201 EP 218 DI 10.1086/308241 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700021 ER PT J AU Novak, G Dotson, JL Dowell, CD Hildebrand, RH Renbarger, T Schleuning, DA AF Novak, G Dotson, JL Dowell, CD Hildebrand, RH Renbarger, T Schleuning, DA TI Submillimeter polarimetric observations of the Galactic center SO ASTROPHYSICAL JOURNAL LA English DT Article DE Galaxy : center; infrared : ISM : continuum; ISM : individual (Sagittarius A); ISM : magnetic fields; polarization ID SAGITTARIUS-A COMPLEX; APERTURE SYNTHESIS OBSERVATIONS; FAR-INFRARED EMISSION; MAGNETIC-FIELD; SGR-A; MOLECULAR CLOUD; CENTER REGION; CENTER ARC; ZEEMAN MEASUREMENTS; RADIO STRUCTURES AB We report the first detection of polarized submillimeter emission from the Sagittarius A region at the Galactic center. We observed three separate 2' x 2' fields: one centered on the circumnuclear disk, one centered on the peak of the molecular cloud M-0.02-0.07 (also called the "50 km s(-1) cloud"), and one centered on the peak of the molecular cloud M-0.13-0.08 (also called the "20 km s(-1) cloud"). Linear polarization at lambda = 350 mu m was detected in each of the three regions, at a total of 106 distinct sky positions. In the circumnuclear disk, the projected magnetic field directions that we infer from our measurements are similar to those inferred from previous far-infrared (lambda = 100 mu m) polarimetry. In the "curved ridge" region of M-0.02-0.07 that has been compressed by the expansion of Sgr A East, our results show clearly the effects of this compression on the magnetic field. In M-0.13-0.08, we observe what appears to be a stretched magnetic field, as expected for this tidally sheared cloud. It has been suggested that a "finger-like extension" or "streamer" from M - 0.13 - 0.08 is falling into the circumnuclear disk. We tentatively interpret a flaring of magnetic field lines that we see in M-0.13-0.08 as evidence that the entire cloud has a velocity component in the Galactic eastern direction, i.e., toward the circumnuclear disk. Further observations are needed to test this interpretation. We argue that polarimetry of dust emission provides a promising tool for obtaining new information on the complex dynamics of neutral gas in the Galactic center. C1 Northwestern Univ, Dept Phys & Astron, Evanston, IL 60208 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Phys, Chicago, IL 60637 USA. RP Novak, G (reprint author), NASA, Ames Res Ctr, SETI Inst, Astrophys Branch, MS 245-6, Moffett Field, CA 94035 USA. EM g-novak@nwu.edu; dotson@cygnus.arc.nasa.gov; cdd@submm.caltech.edu; roger@oddjob.uchicago.edu; renbarger@nwu.edu; david@oddjob.uchicago.edu NR 76 TC 44 Z9 44 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 241 EP 250 DI 10.1086/308231 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700025 ER PT J AU Mannings, V Sargent, AI AF Mannings, V Sargent, AI TI High-resolution studies of gas and dust around young intermediate-mass stars. II. Observations of an additional sample of Herbig Ae systems SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; circumstellar matter; stars : pre-main-sequence ID T-TAURI STARS; MAIN-SEQUENCE EVOLUTION; AE/BE STARS; CIRCUMSTELLAR DISKS; MOLECULAR OUTFLOWS; STELLAR OBJECTS; ACCRETION DISKS; PROTOSTARS; CONTINUUM; EMISSION AB In an earlier paper (Mannings & Sargent; Paper I), we presented evidence for disks of gas and dust associated with seven Herbig Ae stars, based on high-resolution interferometric millimeter-wave observations of continuum and molecular line emission. These systems are simultaneously high-mass analogs of the approximately solar-mass T Tauri stars and the evolutionary precursors of the prototypical main-sequence debris-disk sources beta Pic, alpha Lyr, and alpha PsA. Here we extend the original survey to include four additional Herbig Ae systems. We have also imaged two of the sources from Paper I at higher resolution. The new data are presented and analyzed, and are combined with the results from the earlier sample in order to address the properties of this class of circumstellar disk. Derived disk masses are indistinguishable from the masses of T Tauri disks. Although the combined sample is small, it seems likely that disk masses are essentially uncorrelated with stellar mass for pre-main-sequence stars of spectral type A0 and later. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. RP Mannings, V (reprint author), CALTECH, Jet Prop Lab, MS 169-327,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 52 TC 111 Z9 112 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 391 EP 401 DI 10.1086/308253 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700034 ER PT J AU Boroson, B Kallman, T Vrtilek, SD Raymond, J Still, M Bautista, M Quaintrell, H AF Boroson, B Kallman, T Vrtilek, SD Raymond, J Still, M Bautista, M Quaintrell, H TI Hercules X-1: Empirical models of ultraviolet emission lines SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : eclipsing; line : profiles; stars : individual (Hercules X-1); ultraviolet : stars ID X-RAY BINARIES; COMPTON HEATED WINDS; ACCRETION DISKS; HZ-HERCULIS; PRECESSION; DYNAMICS; CORONAE; ORIGIN; IUE; IV AB The UV emission lines of Hercules X-1, resolved with the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph and Space Telescope Imaging Spectrograph, can be divided into broad (FWHM approximate to 750 km s(-1)) and narrow (FWHM approximate to 150 km s(-1)) components. The broad lines can be unambiguously identified with emission from an accretion disk which rotates prograde with the orbit. The narrow lines, previously identified with the X-ray-illuminated atmosphere of the companion star, are blueshifted at both phi = 0.2 and phi = 0.8, and the line flux at phi = 0.2 is approximate to 0.2 of the flux at phi = 0.8. Line ratio diagnostics show that the density of the narrow-line region is log n(e) = 13.4 +/- 0.2, and T-e = 1.0 +/- 0.2 x 10(5) K. The symmetry of the eclipse ingress suggests that the line emission on the surface of the disk is left-right symmetric relative to the orbit. Model fits to the O v, Si IV, and He II line profiles agree with this result, but fits to the N v lines suggest that the receding side of the disk is brighter. We note that there are narrow absorption components in the N v lines with blueshifts of approximate to 500 km s(-1). C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Open Univ, Milton Keynes MK7 6AA, Bucks, England. RP Boroson, B (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 51 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 414 EP 427 DI 10.1086/308272 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700036 ER PT J AU Giles, AB Galloway, DK Greenhill, JG Storey, MC Wilson, CA AF Giles, AB Galloway, DK Greenhill, JG Storey, MC Wilson, CA TI Pulse profiles, accretion column dips, and a flare in GX 1+4 during a faint state SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; pulsars : individual (GX 1+4); stars : neutron; X-rays : stars ID COUNTER ARRAY EXPERIMENT; RAY TIMING EXPLORER; NEUTRON-STARS; GX-1+4; LUMINOSITY AB The Rossi X-ray Timing Explorer spacecraft observed the X-ray pulsar GX 1+4 for a period of 34 hr on 1996 July 19/20. The source faded from an intensity of similar to 20 mcrab to a minimum of less than or equal to 0.7 mcrab and then partially recovered toward the end of the observation. This extended minimum lasted similar to 40,000 s. Phase-folded light curves at a barycentric rotation period of 124.36568 +/- 0.00020 a show that near the center of the extended minimum the source stopped pulsing in the traditional sense but retained a weak dip feature at the rotation period. Away from the extended minimum, the dips are progressively narrower at higher energies and may be interpreted as obscurations or eclipses of the hot spot by the accretion column. The pulse profile changed from leading-edge bright before the extended minimum to trailing-edge bright after it. Data from the Burst and Transient Source Experiment show that a torque reversal occurred less than 10 days after our observation. Our data indicate that the observed rotation departs from a constant period with a (P) over dot/P value of similar to-1.5% per year at a 4.5 sigma significance. We infer that we may have serendipitously obtained data, with high sensitivity and temporal resolution about the time of an accretion disk spin reversal. We also observed a rapid flare that had some precursor activity, close to the center of the extended minimum. C1 Univ Tasmania, Sch Math & Phys, Hobart, Tas 7001, Australia. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Sydney, Sch Phys, Special Res Ctr Theoret Astrophys, Sydney, NSW 2006, Australia. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Giles, AB (reprint author), Univ Tasmania, Sch Math & Phys, GPO Box 252-21, Hobart, Tas 7001, Australia. RI Greenhill, John/C-8367-2013; OI Galloway, Duncan/0000-0002-6558-5121 NR 27 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 447 EP 452 DI 10.1086/308265 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700039 ER PT J AU Ciaravella, A Raymond, JC Thompson, BJ van Ballegooijen, A Strachan, L Li, J Gardner, L O'Neal, R Antonucci, E Kohl, J Noci, G AF Ciaravella, A Raymond, JC Thompson, BJ van Ballegooijen, A Strachan, L Li, J Gardner, L O'Neal, R Antonucci, E Kohl, J Noci, G TI Solar and heliospheric observatory observations of a helical coronal mass ejection SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : prominences; Sun : UV radiation ID ERUPTIVE PROMINENCE; SOHO; SPECTROMETER; FLARES; REGION; LASCO; SUN AB The EUV Imaging Telescope (EIT), Large Angle Spectrometric Coronagraph (LASCO), and Ultraviolet Coronagraph Spectrometer (UVCS) instruments aboard the SOHO satellite observed a prominence eruption (coronal mass ejection) on 1997 December 12. Ejected plasma moved at about 130 km s(-1) in the plane of the sky and showed Doppler shifts between -350 and +30 km s(-1). The eruption appeared as a strongly curved arch in EIT images low in the corona. Emission in ions ranging from Si III to O VI in the UVCS spectra indicates a temperature range between 10(4.5) and 10(5.5) K. The morphology of the bright emission regions seen by all three instruments suggests several strands of a helical structure of moderate pitch angle. A reasonable fit to the spatial structure and the velocity evolution measured by UVCS is provided by a left-handed helix untwisting at a rate of about 9 x 10(-4) radians s(-1). C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Dipartimento Sci Fis & Astron, I-90134 Palermo, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Osservatorio Astron Torino, I-10125 Pino Torinese, Italy. Univ Florence, Dipartimento Astron & Sci Spazio, I-50125 Florence, Italy. RP Ciaravella, A (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Thompson, Barbara/C-9429-2012 NR 43 TC 63 Z9 63 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 575 EP 591 DI 10.1086/308260 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700050 ER PT J AU Ofman, L Romoli, M Poletto, G Noci, G Kohl, JL AF Ofman, L Romoli, M Poletto, G Noci, G Kohl, JL TI UVCSWLC observations of compressional waves in the south polar coronal hole SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; solar wind; Sun : corona; Sun : magnetic fields; waves ID SOLAR-WIND ACCELERATION; SOLITARY WAVES; SPECTROMETER AB Recent SOHO Ultraviolet Coronagraph Spectrometer (UVCS) white light channel (WLC) observations of the south polar coronal hole plumes and interplume regions produce signatures of quasi-periodic variations in the polarized brightness (pB) at a heliocentric distance of 1.9 solar radii (R.). The Fourier power spectrum of the pB time series shows significant peaks at about 1.6-2.5 mHz and additional smaller peaks at longer and shorter timescales. Wavelet analysis of the pB time series shows that the coherence time of the fluctuations is about 30 minutes. The new observations strongly suggest that the fluctuations are compressional wave packets propagating in the coronal hole high above the limb. The presence of compressional waves may have important implications that help to explain the heating of coronal holes and the fast solar wind acceleration. C1 Raytheon ITSS, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Florence, Dept Astron & Space Sci, I-50125 Florence, Italy. Arcetri Observ, I-50125 Florence, Italy. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Ofman, L (reprint author), Raytheon ITSS, Mail Code 682, Greenbelt, MD 20771 USA. RI Romoli, Marco/H-6859-2012 NR 18 TC 81 Z9 81 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 592 EP 598 DI 10.1086/308252 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700051 ER PT J AU Greenwood, JB Chutjian, A Smith, SJ AF Greenwood, JB Chutjian, A Smith, SJ TI Measurements of absolute, single charge-exchange cross sections of H(+), He(+) and He(2+) with H(2)O and CO(2) SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; comets : individual (Halley); solar wind ID X-RAY; IONS; JUPITER; EMISSION; COMA AB Absolute measurements have been made of single-electron charge-exchange cross sections of H(+), He(+), and He(2+) in H(2)O and CO(2) in the energy range 0.3-7.5 keV amu(-1). Collisions of this type occur in the interaction of solar wind ions with cometary gases and have been observed by the Giotto spacecraft using the Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) during a close encounter with comet Halley in 1986. Increases in the He(+) ion density, and in the He(2+) to H(+) density ratio were reported by Shelley et al, and Fuselier et al. and were explained by charge exchange. However, the lack of reliable cross sections for this process made interpretation of the data difficult. New cross sections are presented and discussed in relation to the Giotto observations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Greenwood, JB (reprint author), Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. EM j.b.greenwood@queens-belfast.ac.uk; ara.chutjian@jpl.nasa.gov; steven.j.smith@jpl.nasa.gov RI Greenwood, Jason/L-4799-2014 NR 19 TC 48 Z9 49 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP 605 EP 609 DI 10.1086/308254 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LW UT WOS:000085334700053 ER PT J AU Reiner, MJ Kaiser, ML Plunkett, SP Prestage, NP Manning, R AF Reiner, MJ Kaiser, ML Plunkett, SP Prestage, NP Manning, R TI Radio tracking of a white-light coronal mass ejection from solar corona to interplanetary medium SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar-terrestrial relations; Sun : activity; Sun : corona; Sun : flares; Sun : radio radiation ID II BURSTS; WIND SPACECRAFT; SHOCKS; WAVES AB For a solar flare/coronal mass ejection (CME) event on 1999 May 3, type II radio emissions were observed from the metric through the hectometric wavelength regimes. By comparing the dynamics of the CME with that implied by the frequency range and frequency drift rates of the type II radio emissions, it is concluded that the decametric-hectometric type IT radio emissions were associated with the CME. The dynamics implied by the metric type II radio burst suggest a distinct coronal shock, associated with the flare, which only produced radio emissions in the low corona. C1 Raytheon ITSS, Lanham, MD 20706 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. USN, Res Lab, Univ Space Res Assoc, Washington, DC 20375 USA. Culgoora Solar Observ, IPS Radio & Space Serv, Narrabri, NSW 2390, Australia. Observ Paris, DESPA, F-92195 Meudon, France. RP Reiner, MJ (reprint author), Raytheon ITSS, Lanham, MD 20706 USA. NR 15 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 2000 VL 529 IS 1 BP L53 EP L56 DI 10.1086/312446 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 284LX UT WOS:000085334800014 ER PT J AU Weishampel, JF Blair, JB Knox, RG Dubayah, R Clark, DB AF Weishampel, JF Blair, JB Knox, RG Dubayah, R Clark, DB TI Volumetric lidar return patterns from an old-growth tropical rainforest canopy SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID LACUNARITY ANALYSIS; FORESTS; LIGHT AB Rainforests represent the epitome of structural complexity in terrestrial ecosystems. However, measures of three-dimensional canopy structure are limited to a few areas typically <1 ha with construction crane or walkway/platform access,An innovative laser profiling system, the Laser Vegetation Imaging Sensor (LVIS), was used to map canopy structure (i.e. based on height and vertical distribution of laser returns) of a tropical rainforest in Costa Rica. Within a approximate to 1 km(2) area of mature rainforest, canopy top height ranged from 8.4 to 51.6 m based on the altimeter measures. The laser return density was most concentrated in the horizontal layer located 20-30 m above the ground. Spatial patterns of the return were found to be isotropic based on north-south versus east-west vertical return profiles and exhibited properties of self-similarity. C1 Univ Cent Florida, Dept Biol, Orlando, FL 32816 USA. NASA, Goddard Space Flight Ctr, Laser Remote Sensing Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Univ Missouri, Dept Biol, St Louis, MO 63121 USA. RP Weishampel, JF (reprint author), Univ Cent Florida, Dept Biol, Orlando, FL 32816 USA. RI Mitchard, Edward/C-6346-2009; Knox, Robert/E-9657-2011; Blair, James/D-3881-2013; Beckley, Matthew/D-4547-2013 NR 24 TC 64 Z9 67 U1 2 U2 11 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JAN 20 PY 2000 VL 21 IS 2 BP 409 EP 415 DI 10.1080/014311600210939 PG 7 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 272ZK UT WOS:000084681200015 ER PT J AU Notholt, J Toon, GC Rinsland, CP Pougatchev, NS Jones, NB Connor, BJ Weller, R Gautrois, M Schrems, O AF Notholt, J Toon, GC Rinsland, CP Pougatchev, NS Jones, NB Connor, BJ Weller, R Gautrois, M Schrems, O TI Latitudinal variations of trace gas concentrations in the free troposphere measured by solar absorption spectroscopy during a ship cruise SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC CARBON-MONOXIDE; INFRARED MEASUREMENTS; SEASONAL-VARIATIONS; COLUMN ABUNDANCES; ERROR ANALYSIS; SPECTROMETRY; STRATOSPHERE; METHANE; SPECTRA; TRENDS AB The latitudinal variations of atmospheric trace gas column abundances have been measured during a ship cruise between 57 degrees N and 45 degrees S on the central Atlantic. The measurements were performed in October 1996 using high-resolution solar absorption spectroscopy in the infrared. The analysis method employed permits the retrieval of the total column densities of 20 different trace gases and for a few compounds the vertical mixing ratio profiles. For CH4 an interhemispheric difference of 3% was observed. The total columns of the shorter-lived trace gases CO and C2H6, analyzed between 57 degrees N and 45 degrees S, reveal a slight maximum in the tropics and a substantial increase north of 45 degrees N. The total columns of C2H2 and HCN, detectable between 30 degrees N and 30 degrees S, reveal a maximum in the tropics of the Southern Hemisphere. For CH2O, studied between 57 degrees N and 45 degrees S, a well-pronounced maximum is observed in the tropics. The profile retrieval gives high mixing ratios for CO, C2H6 and O-3 north of 40 degrees N in the lower troposphere. In the tropics high concentrations are found for all three compounds in the entire troposphere, even above 12 km. The measurements have been used to estimate averaged mixing ratios of the trace gases for the free troposphere between 0 and 12 km. In the tropics the data give high values: for example, more than 200 pptv for HCN, 750 pptv for CH2O, 100 ppbv for CO and 100 pptv for C2H2 These values are comparable to or higher than what has been observed at midlatitudes, indicating the importance of biomass burning emissions on the tropospheric composition. C1 Alfred Wegener Inst Polar & Marine Res, D-14473 Potsdam, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Christopher Newport Univ, Dept Phys, Newport News, VA 23606 USA. Natl Inst Water & Atmospher Res, Lauder, New Zealand. Alfred Wegener Inst Polar & Marine Res, D-27570 Bremerhaven, Germany. Forschungszentrum Julich, Inst Atmosphar Chem ICG3, D-52425 Julich, Germany. RP Notholt, J (reprint author), Alfred Wegener Inst Polar & Marine Res, Telegraphenberg A43, D-14473 Potsdam, Germany. EM jnotholt@awi-potsdam.de RI Notholt, Justus/P-4520-2016 OI Notholt, Justus/0000-0002-3324-885X NR 45 TC 39 Z9 39 U1 1 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 20 PY 2000 VL 105 IS D1 BP 1337 EP 1349 DI 10.1029/1999JD900940 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 276BW UT WOS:000084856600003 ER PT J AU Kondo, Y Sugita, T Koike, M Kawa, SR Danilin, MY Rodriguez, JM Spreng, S Golinger, K Arnold, F AF Kondo, Y Sugita, T Koike, M Kawa, SR Danilin, MY Rodriguez, JM Spreng, S Golinger, K Arnold, F TI Partitioning of reactive nitrogen in the midlatitude lower stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PINATUBO AEROSOLS; SULFURIC-ACID; CHLORINE; NO2; CHEMISTRY; AIRCRAFT; RADICALS; HNO3; O-3 AB Balloon-borne in situ measurements of total reactive nitrogen (NO,), nitric oxide (NO), nitric acid (HNO3), ozone (O-3), and aerosols were conducted over Are sur l'Adour, France (44 degrees N), between October 11 and 12, 1994, NO, and NO were measured by chemiluminescence NO detectors combined with a gold catalytic converter, and HNO3, was measured by ion mass spectrometry. Two independent box models (Goddard Space Flight Center and Atmospheric and Environment Inc.) run on isentropic trajectories were used to interpret the observed partitioning of reactive nitrogen. The NO partitioning calculated by the two models agreed within 10% of each other. The model-calculated NO/ NO ratios increase by similar to 25% when the updated reaction rates of NO2 + OH, HNO3 + OH, and NO2 + O [Portpnann et al., 1999] were used instead of those given by DeMore ei al. [1997], leading to a better agreement with the observations by the same amount. At 21-25 km the calculated NO/NOy, ratios depended sensitively on the estimate of aerosol surface area. Within the uncertainty of the estimate of aerosol surface area the NO/NOy, and HNO3/NOy ratios calculated by the models reproduced those observed within 20%. The same trajectory models also reproduced the NO/NOy ratios measured below 25 km under high aerosol loading in October and November 1992 within +/-20%, which is the accuracy level of the measurements. C1 Nagoya Univ, Solar Terr Environm Lab, Aichi 4428507, Japan. Natl Inst Environm Studies, Tsukuba, Ibaraki 3050053, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Dept Marine & Atmospher Chem, Miami, FL 33149 USA. Max Planck Inst Kernphys, Atmospher Phys Div, D-69029 Heidelberg, Germany. RP Kondo, Y (reprint author), Nagoya Univ, Solar Terr Environm Lab, 3-13 Honohara, Aichi 4428507, Japan. EM kondo@stelab.nagoya-u.ac.jp; tsugita@nies.go.jp; koike@stelab.nagoya-u.ac.jp; kawa@maia.gsfc.nasa.gov; danilin@aer.com; jrodriguez@rsmas.miami.edu RI Koike, Makoto/F-4366-2011; Kondo, Yutaka/D-1459-2012; Kawa, Stephan/E-9040-2012; Rodriguez, Jose/G-3751-2013; OI Rodriguez, Jose/0000-0002-1902-4649; Sugita, Takafumi/0000-0002-0508-7040 NR 34 TC 10 Z9 10 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 20 PY 2000 VL 105 IS D1 BP 1417 EP 1424 DI 10.1029/1999JD901012 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 276BW UT WOS:000084856600007 ER PT J AU Schoeberl, MR Sparling, LC Jackman, CH Fleming, EL AF Schoeberl, MR Sparling, LC Jackman, CH Fleming, EL TI A Lagrangian view of stratospheric trace gas distributions SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CARBON-DIOXIDE; INSTRUMENTS ABOARD; ER-2 AIRCRAFT; TRANSPORT; AIR; CONSTITUENTS; TROPOSPHERE; ATMOS; AGE; VORTEX AB As a result of photochemistry, some relationship between the stratospheric age of air or mean age and the amount of tracer contained within an air sample is expected. The existence of such a relationship allows inferences about transport history to be made from observations of chemical tracers. This paper lays down the conceptual foundations for the relationship between age and tracer amount for long-lived tracers, developed within a Lagrangian framework. Although the photochemical loss depends not only on the age of the parcel but also on its path, we show that under the "average path approximation" that the path variations are less important than parcel age. The average path approximation then allows us to develop a formal relationship between the age spectrum and the tracer distribution. Using this relationship, tracer-tracer correlations can be interpreted as the result of mixing which connects parts of the "single-path photochemistry curve," a universal path-independent curve that describes the photochemical loss in terms of the total photon exposure. This geometric interpretation of mixing gives rise to constraints on trace gas correlation curves as can be seen in the atmospheric trace molecule spectroscopy observations. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. Raytheon STX, Laurel, MD USA. RP Schoeberl, MR (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. EM schom@zephyr.gsfc.nasa.gov; sparling@dynarama.gsfc.nasa.gov; jackman@assess.gsfc.nasa.gov RI Jackman, Charles/D-4699-2012 NR 31 TC 24 Z9 24 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 20 PY 2000 VL 105 IS D1 BP 1537 EP 1552 DI 10.1029/1999JD900787 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 276BW UT WOS:000084856600018 ER PT J AU Hack, MD Jasper, AW Volobuev, YL Schwenke, DW Truhlar, DG AF Hack, MD Jasper, AW Volobuev, YL Schwenke, DW Truhlar, DG TI Do semiclassical trajectory theories provide an accurate picture of radiationless decay for systems with accessible surface crossings? SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID VIBRATIONAL ENERGY-TRANSFER; ELECTRONIC DEGREES; CLASSICAL ANALOG; DYNAMICS; DISSOCIATION; MOLECULES; SECTIONS; FREEDOM; STATE AB We present quantum mechanical and semiclassical calculations of Feshbach funnel resonances that correspond to long-lived exciplexes in the (A) over tilde B-2(2) State of NaH2. These exciplexes decay to the ground state, (X) over tilde (2)A(1), by a surface crossing in C-2v geometry. The quantum mechanical lifetimes and the branching probabilities for competing decay mechanisms are computed for two different NaH2 potential energy matrices, and we explain the results in terms of features of the potential energy matrices. We compare the quantum mechanical calculations of the lifetimes and the average vibrational and rotational quantum numbers of the decay product, H-2, to two kinds of semiclassical trajectory calculations: the trajectory surface hopping method and the Ehrenfest self-consistent potential method (also called the time-dependent self-consistent field method). The trajectory surface hopping calculations use Tully's fewest switches algorithm and two different prescriptions for adjusting the momentum during a hop. Both the adiabatic and the diabatic representations are used for the trajectory surface hopping calculations. We show that the diabatic surface hopping calculations agree better with the quantum mechanical calculations than the adiabatic surface hopping calculations or the Ehrenfest calculations do for one potential energy matrix, and the adiabatic surface hopping calculations agree best with the quantum mechanical calculations for the other potential energy matrix. We test three criteria for predicting which representation is most accurate for surface hopping calculations. We compare the ability of the semiclassical methods to accurately reproduce the quantum mechanical trends between the two potential matrices, and we review other recent comparisons of semiclassical and quantum mechanical calculations for a variety of potential matrices. On the basis of the evidence so far accumulated, we conclude that for general three-dimensional two-state systems, Tully's fewest switches method is the most accurate semiclassical method currently available if (i) one uses the nonadiabatic coupling vector as the hopping vector and (ii) one propagates the trajectories in the representation that minimizes the number of surface hops. C1 Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA. Univ Minnesota, Inst Supercomp, Minneapolis, MN 55455 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Truhlar, DG (reprint author), Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA. RI Jasper, Ahren/A-5292-2011; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Truhlar, Donald/0000-0002-7742-7294 NR 42 TC 41 Z9 41 U1 0 U2 5 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD JAN 20 PY 2000 VL 104 IS 2 BP 217 EP 232 DI 10.1021/jp993353x PG 16 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 278TX UT WOS:000085006000006 ER PT J AU Nickolaisen, SL Roehl, CM Blakeley, LK Friedl, RR Francisco, JS Liu, RF Sander, SP AF Nickolaisen, SL Roehl, CM Blakeley, LK Friedl, RR Francisco, JS Liu, RF Sander, SP TI Temperature dependence of the HO2+ClOreaction. 1. Reaction kinetics by pulsed photolysis-ultraviolet absorption and ab initio studies of the potential surface SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID THERMAL UNIMOLECULAR REACTIONS; MODULATED PHOTOLYSIS; RELATIVE STABILITIES; PRESSURE-DEPENDENCE; VIBRATIONAL-SPECTRA; RATE CONSTANTS; REACTION CLO; HO2; RADICALS; PRODUCT AB The kinetics of the HO2 + ClO reaction was studied using the flash photolysis/ultraviolet absorption technique over the temperature range 203-364 K and pressure range 50-700 Torr of NS In contrast to previous work, the temperature dependence displayed linear Arrhenius behavior over the entire temperature range with the rate constant being described by the expression k(T) = 2.84 x 10(-12) exp{(312 +/- 60)/T} cm(3) molecule(-1) s(-1) Ab initio calculations of intermediates and transition states have been carried our: on the singlet and triplet potential energy surfaces. These calculations show that the reaction proceeds mainly through the ClO-HO2 complex on the triplet surface; however, collisionally stabilized HOOOCl formed on the singlet surface will possess an appreciable lifetime due to large barriers toward decomposition to HCl and HOCl. Termolecular rate calculations using ab initio parameters lead to a strong collision rate constant of similar to 5 X 10(-32) cm(6) molecule(-2) s(-1) for HOOOCl formation. This intermediate may be important under both laboratory and atmospheric conditions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Calif State Univ Los Angeles, Dept Chem & Biochem, Los Angeles, CA 90032 USA. Purdue Univ, Dept Earth & Atmospher Sci, W Lafayette, IN 47907 USA. E Tennessee State Univ, Dept Chem, Johnson City, TN 37614 USA. RP Sander, SP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 44 TC 22 Z9 22 U1 0 U2 8 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD JAN 20 PY 2000 VL 104 IS 2 BP 308 EP 319 DI 10.1021/jp992753h PG 12 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 278TX UT WOS:000085006000018 ER PT J AU Liu, AS Chuang, SL Ning, CZ AF Liu, AS Chuang, SL Ning, CZ TI Piezoelectric field-enhanced second-order nonlinear optical susceptibilities in wurtzite GaN/AlGaN quantum wells SO APPLIED PHYSICS LETTERS LA English DT Article ID 2ND-HARMONIC GENERATION; 2ND-ORDER SUSCEPTIBILITY; INTERSUBBAND TRANSITIONS; RECTIFICATION AB Second-order nonlinear optical processes including second-harmonic generation, optical rectification, and difference-frequency generation associated with intersubband transitions in wurtzite GaN/AlGaN quantum well (QW) are investigated theoretically. Taking into account the strain-induced piezoelectric (PZ) effects, we solve the electronic structure of the QW from coupled effective-mass Schrodinger equation and Poisson equation including the exchange-correlation effect under the local-density approximation. We show that the large PZ field in the QW breaks the symmetry of the confinement potential profile and leads to large second-order susceptibilities. We also show that the interband optical pump-induced electron-hole plasma results in an enhancement in the maximum value of the nonlinear coefficients and a redshift of the peak position in the nonlinear optical spectrum. By use of the difference-frequency generation, THz radiation can be generated from a GaN/Al(0.75)Ga(0.25)N with a pump laser of 1.55 mu m. (C) 2000 American Institute of Physics. [S0003-6951(00)01203-1]. C1 Arizona State Univ, Dept Elect Engn, Tempe, AZ 85287 USA. Univ Illinois, Dept Elect & Comp Engn, Urbana, IL 61801 USA. RP Liu, AS (reprint author), NASA, Ames Res Ctr, M-S N229-1, Moffett Field, CA 94035 USA. RI Ning, C. Z./D-4699-2009 OI Ning, C. Z./0000-0003-4583-8889 NR 15 TC 50 Z9 51 U1 1 U2 7 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JAN 17 PY 2000 VL 76 IS 3 BP 333 EP 335 DI 10.1063/1.125736 PG 3 WC Physics, Applied SC Physics GA 272WZ UT WOS:000084675100028 ER PT J AU Nayagam, V Williams, FA AF Nayagam, V Williams, FA TI Rotating spiral edge flames in von Karman swirling flows SO PHYSICAL REVIEW LETTERS LA English DT Article ID CELLULAR FLAMES; EXCITABLE MEDIA; WAVES; PROPAGATION; COMBUSTION; TRANSITION; DYNAMICS; RINGS; LIMIT AB Experimental observations of rotating spiral flame edges formed during near-limit combustion of a downward-facing, polymethylmethacrylate disk spinning in quiescent air are reported. These flames exhibit similarities to patterns commonly found in quiescent excitable media. The tail rotates rigidly while the tip executes a compound, meandering motion sometimes observed in Belousov-Zhabotinskii reactions. A model assuming a rigid-body rotation with a constant speed of propagation relative to the swirling gas flow generated by the spinning disk predicts the observed spiral shapes well. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. Univ Calif San Diego, MAE Dept, La Jolla, CA 92093 USA. RP Nayagam, V (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. NR 28 TC 21 Z9 22 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD JAN 17 PY 2000 VL 84 IS 3 BP 479 EP 482 DI 10.1103/PhysRevLett.84.479 PG 4 WC Physics, Multidisciplinary SC Physics GA 274WD UT WOS:000084787300021 ER PT J AU Gopalswamy, N Lara, A Lepping, RP Kaiser, ML Berdichevsky, D St Cyr, OC AF Gopalswamy, N Lara, A Lepping, RP Kaiser, ML Berdichevsky, D St Cyr, OC TI Interplanetary acceleration of coronal mass ejections SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETIC CLOUDS AB Using an observed relation between speeds of CMEs near the Sun and in the solar wind, we determine an "effective" acceleration acting on the CMEs. We found a linear relation between this effective acceleration and the initial speed of the CMEs. The acceleration is similar to that of the slow solar wind in magnitude. The average solar wind speed naturally divides CMEs into fast and slow ones. Based on the relation between the acceleration and initial speed, we derive an empirical model to predict the arrival of CMEs at 1 AU. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Washington, DC 20064 USA. Raytheon ITSS, Lanham, MD 20740 USA. USN, Res Lab, Washington, DC 20375 USA. RP Gopalswamy, N (reprint author), NASA, Goddard Space Flight Ctr, Bldg 26,Room G1,Mailcode 682-3, Greenbelt, MD 20771 USA. RI Gopalswamy, Nat/D-3659-2012; OI Lara, Alejandro/0000-0001-6336-5291 NR 16 TC 288 Z9 296 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JAN 15 PY 2000 VL 27 IS 2 BP 145 EP 148 DI 10.1029/1999GL003639 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 275FA UT WOS:000084807700002 ER PT J AU Schweighofer, K Benjamin, I AF Schweighofer, K Benjamin, I TI Ion pairing and dissociation at liquid/liquid interfaces: Molecular dynamics and continuum models SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID REORGANIZATION FREE-ENERGY; LIQUID LIQUID INTERFACES; 2ND HARMONIC-GENERATION; MEAN FORCE; AQUEOUS-SOLUTION; SODIUM-CHLORIDE; COMPUTER-SIMULATION; WATER; ASSOCIATION; CAPACITANCE AB The thermodynamics and dynamics of NaCl ion-pair dissociation at the water/1,2-dichloroethane liquid/liquid interface are examined using a continuum electrostatic model, molecular dynamics free energy calculations, and nonequilibrium dynamic trajectory calculations. The continuum model shows increased stability of the ion pair relative to that in bulk water and strong dependence of the potential of mean force on the orientation and location of the ion pair relative to the interface. These are in qualitative agreement with the molecular dynamics results. In particular, the equilibrium free energy calculations show that the ion pair is locally stable at the interface and that the dissociation must involve ion transfer and considerable change in the interface structure. These are also confirmed by the nonequilibrium dynamics calculations: Dissociation of the ion pair at the interface involves a simultaneous transfer of both ions into the aqueous side of the interface. The faster transfer of the sodium than the chloride ion influences the lifetime of the ion pair at the interface. In particular, a strong dependence of the ion pair's stability on its orientation is found. (C) 2000 American Institute of Physics. [S0021-9606(00)50803-4]. C1 Univ Calif Santa Cruz, Dept Chem, Santa Cruz, CA 95064 USA. RP Schweighofer, K (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94143 USA. NR 43 TC 20 Z9 20 U1 1 U2 9 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JAN 15 PY 2000 VL 112 IS 3 BP 1474 EP 1482 DI 10.1063/1.480713 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 271MW UT WOS:000084598900046 ER PT J AU Tselioudis, G Zhang, YC Rossow, WB AF Tselioudis, G Zhang, YC Rossow, WB TI Cloud and radiation variations associated with northern midlatitude low and high sea level pressure regimes SO JOURNAL OF CLIMATE LA English DT Article ID CIRCULATION SYSTEMS; SATELLITE; SURFACE; SENSITIVITY; AEROSOLS; CLIMATE; MODELS; SCHEME; FLUXES AB A global meteorological dataset, a global satellite dataset, and a radiative transfer model are combined to map the cloud types in low, near-normal, and high sea level pressure regimes in the northern midlatitudes, and to calculate the radiative balance in those regimes. The prominent cloud feature is a background cloud Field that is present most of the time and is modulated by changes in dynamic regime, It consists of a low cloud deck, which becomes optically thicker in the warm reasons over ocean and in the cold seasons over land, and a population of optically thin middle-to-high-top clouds that is mostly middle-top in the cold and mostly high-top in the warm seasons. This background cloud field is modulated by the emergence of a population of optically thick high-top clouds in the low pressure regime and by an increase in the optical thickness of the low clouds in the high pressure regime. The top-of-the-atmosphere (TOA) shortwave Run differences between dynamic regimes show that men sunlight is reflected in the low than in the high pressure regime. In January TOA shortwave flux differences between regimes range between 5 and 20 W m(-2) and in July between 20 and 50 W m(-2). and those differences are manifested as a net excess cooling at the earth's surface. The TOA longwave budget shows more heat trapped in the troposphere in the low pressure than in the high pressure regime. The differences in the TOA outgoing longwave fluxes between the two extreme regimes range in all seasons between 5 and 35 W m(-2) and are manifested mostly as an additional warming in the atmospheric column. The TOA total flux differences between the low and high pressure regimes change both sign and magnitude with season: in the winter an excess warming of 5-15 W m(-2) is found in the low pressure regime while in all other seasons on excess cooling, which ranges between 10 and 40 W m(-2), is found. Preliminary investigations with the Goddard Institute for Space Studies GCM show that changes in midlatitude dynamics with climate can produce significant radiation feedbacks. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Phys, New York, NY 10027 USA. RP Tselioudis, G (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Rossow, William/F-3138-2015 NR 24 TC 57 Z9 58 U1 0 U2 8 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JAN 15 PY 2000 VL 13 IS 2 BP 312 EP 327 DI 10.1175/1520-0442(2000)013<0312:CARVAW>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 282PX UT WOS:000085228200002 ER PT J AU Bell, TL Kundu, PK AF Bell, TL Kundu, PK TI Dependence of satellite sampling error on monthly averaged rain rates: Comparison of simple models and recent studies SO JOURNAL OF CLIMATE LA English DT Article ID MEASURING MISSION TRMM; TROPICAL RAINFALL; STOCHASTIC-MODEL; THRESHOLD METHOD; PRECIPITATION; RADAR; SIMULATION AB Considerable progress has been made in recent years with using satellite data to generate maps of rain rate with grid resolutions of 1 degrees-5 degrees square. In parallel with these efforts, much work has been devoted to the problem of attaching error estimates to these products. There are two main sources of error, the intrinsic errors in the remote sensing measurements themselves (retrieval errors) and the lack of continuity in the coverage by low earth-orbiting satellites (sampling error). Perhaps a dozen or so studies have attempted to estimate the sampling-error component. These studies have been based on rain gauge and radar-derived data, and the estimates vary so much that it is clear that the sampling error cannot be represented satisfactorily by a single value. These studies are reviewed. Some of the results reported in these studies are based on a method referred to in this paper as "resampling by shifts." The authors find that the method unfortunately tends to produce estimates that are subject to too much uncertainty to be used quantitatively. After setting these results aside, the authors find that the variability in the remaining sampling-error estimates can be explained to a considerable extent using assumptions common to many statistical models of rain. All such models predict that sampling error relative to the average rain rate R is proportional to R-1/2. Although the sampling error at any given site seems (to the extent that data have been examined) to change with R in the way predicted by the model, the proportionality constant in this relationship seen in the various studies appears to change from site to sire. This constant can be obtained from the satellite estimates themselves if retrieval errors are not correlated over scales of the order of the grid-box size. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Bell, TL (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 913, Greenbelt, MD 20771 USA. RI Bell, Thomas/G-5425-2012; Kundu, Prasun/C-7212-2013 OI Kundu, Prasun/0000-0002-2284-9852 NR 34 TC 57 Z9 57 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JAN 15 PY 2000 VL 13 IS 2 BP 449 EP 462 DI 10.1175/1520-0442(2000)013<0449:DOSSEO>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 282PX UT WOS:000085228200011 ER PT J AU Nakamura, M Chao, Y AF Nakamura, M Chao, Y TI On the eddy isopycnal thickness diffusivity of the Gent-McWilliams subgrid mixing parameterization SO JOURNAL OF CLIMATE LA English DT Article ID OCEAN CIRCULATION MODELS; GENERAL-CIRCULATION; TRACER TRANSPORTS; BOMB RADIOCARBON; EDDIES; RESOLUTION; SIMULATION; FLUXES; WAVES AB Output of an eddy-resolving model of the North Atlantic Ocean is used to diagnose the eddy thickness diffusivity coefficient, kappa, defined by Gene and McWilliams in their quasi-adiabatic parameterization for transports by mesoscale eddies. The results suggest that kappa has large spatial and temporal variations, with negative values about half of the time. The order of magnitude of kappa shows a wide range in the western North Atlantic, varying from 10 m(2) s(-1) to 10(7) m(2) s(-1). Also, the value of kappa is considerably affected by the timescale used to define the high-frequency and low-frequency components. The results suggest that kappa should be a diagnosed variable that reflects the strength of eddy mixing during a model integration. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Nakamura, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-323, Pasadena, CA 91109 USA. NR 32 TC 24 Z9 24 U1 2 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JAN 15 PY 2000 VL 13 IS 2 BP 502 EP 510 DI 10.1175/1520-0442(2000)013<0502:OTEITD>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 282PX UT WOS:000085228200014 ER PT J AU Elfouhaily, T Thompson, DR Chapron, B Vandemark, D AF Elfouhaily, T Thompson, DR Chapron, B Vandemark, D TI Improved electromagnetic bias theory SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA-STATE BIAS; WIND-GENERATED WAVES; NONLINEAR RANDOM SEA; SATELLITE ALTIMETRY; JOINT DISTRIBUTION; RADAR BACKSCATTER; SURFACE; SPECTRUM; SCATTERING; SLOPES AB In this paper we describe modifications to a previous theory for the altimeter electromagnetic bias (EM bias) of Srokosz [1986]. A major correction introduces a scaling of Srokosz's model by nonnegligible dimensionless ratios that depend on the slope variance of both long and short waves. With these modifications the EM bias is no longer simply a function of the cross skewness between surface elevation and slope but now depends on the variance ratios that represent the modulation between short and long waves, Inclusion of these ratios can reduce previous EM bias estimates by as much as 50%. Different directions for the longwave and shortwave field are also accounted for in the two-dimensional development of our approach. A radar frequency dependence consistent with observation is also predicted by the new model. Derivation extending our development to the next higher order in wave statistics is also presented and discussed. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. IFREMER, Ctr Brest, Dept Oceanog Spatiale, F-29280 Plouzane, France. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Wallops Island, VA 23337 USA. RP Elfouhaily, T (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. RI Chapron, Bertrand/O-6527-2015 NR 33 TC 31 Z9 36 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JAN 15 PY 2000 VL 105 IS C1 BP 1299 EP 1310 DI 10.1029/1999JC900277 PG 12 WC Oceanography SC Oceanography GA 275CW UT WOS:000084802700022 ER PT J AU Baker, RD Schubert, G Jones, PW AF Baker, RD Schubert, G Jones, PW TI Convectively generated internal gravity waves in the lower atmosphere of Venus. Part I: No wind shear SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID COMPRESSIBLE CONVECTION; RADIO OCCULTATION; CLOUD AB This paper is the first of a two-part study that investigates internal gravity wave generation by convection in the lower atmosphere of Venus. A two-dimensional, nonlinear, fully compressible model of a perfect gas is employed. The calculations consider the lower atmosphere from 12- to 60-km altitude, thereby including two convection regions: the lower atmosphere convection layer from roughly 18- to 30-km altitude and the cloud-level convection layer from roughly 48- to 55-km altitude. The gravity waves of interest are located in the stable layer between these two convection regions. Part I of this study considers gravity wave generation and propagation in the absence of mean wind shear. In the absence of mean wind shear, internal gravity waves are primarily generated by cloud-level convection. Horizontal wavelengths (similar to 10-15 km) are similar to dominant horizontal scales in the cloud-level penetrative region, and intrinsic horizontal phase speeds are comparable to cloud-level downdraft velocities. Without mean wind shear, there is no effective coupling between the lower atmosphere below 34-km altitude and the overlying stable layer. Simulated wave amplitudes and vertical wavelengths agree well with spacecraft observations, suggesting that gravity waves generated by cloud-level convection through the "mechanical oscillator" effect may be responsible for observed variations in the stable layer. C1 Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA. Univ Calif Los Alamos Natl Lab, Div Theoret, Los Alamos, NM USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. RP Baker, RD (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 912, Greenbelt, MD 20771 USA. NR 39 TC 14 Z9 14 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JAN 15 PY 2000 VL 57 IS 2 BP 184 EP 199 DI 10.1175/1520-0469(2000)057<0184:CGIGWI>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 276NX UT WOS:000084885300002 ER PT J AU Baker, RD Schubert, G Jones, PW AF Baker, RD Schubert, G Jones, PW TI Convectively generated internal gravity waves in the lower atmosphere of Venus. Part II: Mean wind shear and wave-mean flow interaction SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID COMPRESSIBLE CONVECTION; NUMERICAL EXPERIMENTS; RADIO OCCULTATION; SUPERROTATION; TURBULENCE; STRATOSPHERE; SIMULATIONS; SENSITIVITY; MAINTENANCE; ROTATION AB This paper is the second of a two-part study that numerically investigates internal gravity wave generation by convection in the lower atmosphere of Venus. Part I of this study considers gravity wave generation and propagation in the absence of mean wind shear. In Part II, the Venus westward superroration is included, and wave-mean flow interaction is assessed. Both lower-atmosphere convection and cloud-level convection play active roles in the dynamics of the stable layer from 31- to 47-km altitude when mean wind shear is present. This result contrasts with the simulation without mean wind shear presented in Part I where cloud-level collection was primarily responsible for gravity wave generation in the stable layer. In the presence of mean wind shear, upward entrainment from lower-atmosphere convection and downward penetration from cloud-level convection are comparable in magnitude. Convectively generated internal gravity waves have horizontal wavelengths (similar to 25-30 km) comparable to horizontal scales in both convection layers. Quasi-stationary gravity waves (with respect to the lower convection layer) occur in the lower part of the stable layer, while both eastward- and westward-propagating waves generated by cloud-level convection exist in the upper part of the stable layer. Simulated wave amplitudes and vertical wavelengths agree well with observations. Eastward-propagating waves generated by cloud-level convection experience critical level absorption in the stable layer and thus decelerate the Venus westward superrotation below the clouds. The deceleration is comparable in magnitude to zonal accelerations above the clouds by thermal tides. C1 Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA. Univ Calif Los Alamos Natl Lab, Div Theoret, Los Alamos, NM USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. RP Baker, RD (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 912, Greenbelt, MD 20771 USA. NR 38 TC 22 Z9 22 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JAN 15 PY 2000 VL 57 IS 2 BP 200 EP 215 DI 10.1175/1520-0469(2000)057<0200:CGIGWI>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 276NX UT WOS:000084885300003 ER PT J AU Varnai, T AF Varnai, T TI Influence of three-dimensional radiative effects on the spatial distribution of shortwave cloud reflection SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID INDEPENDENT PIXEL APPROXIMATION; SCALE-INVARIANCE; BROKEN CLOUDS; STRATOCUMULUS; PARAMETERIZATION; RADIANCES; FLUXES; FIELDS; ALBEDO; SHAPE AB This paper examines how three-dimensional radiative effects influence the way cloud fields appear in high-resolution shortwave satellite images. To do so, it uses cloud reflectance fields simulated by a Monte Carlo radiative transfer model. This study examines the influence of the two counteracting three-dimensional mechanisms: the smoothing effect of radiative diffusion, which can reduce brightness variations, and the sharpening effect caused by thick areas intercepting extra radiation through their sides and casting shadows on the thin areas behind them, which can enhance brightness variability. The findings suggest that current high-resolution retrievals of cloud structure can be significantly biased because they do not take these effects into account. For oblique sun. high-resolution retrievals can overestimate both the scene-averaged optical thickness and the magnitude of cloud variability, and yield systematically distorted cloud shapes and artificially anisotropic cloud structures. It is shown that the biases are especially large when cloud-top height variations are present because cloud-top variations can cause a much stronger sharpening effect than internal cloud variability. To prevent erroneous interpretation of retrieval results, an algorithm is proposed to determine whether retrievals based on any satellite image are affected significantly by these biases. C1 McGill Univ, Dept Atmospher & Ocean Sci, Montreal, PQ, Canada. RP Varnai, T (reprint author), NASA, Climate & Radiat Branch, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. NR 30 TC 39 Z9 39 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JAN 15 PY 2000 VL 57 IS 2 BP 216 EP 229 DI 10.1175/1520-0469(2000)057<0216:IOTDRE>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 276NX UT WOS:000084885300004 ER PT J AU Weaver, CJ Douglass, AR Rood, RB AF Weaver, CJ Douglass, AR Rood, RB TI Lamination frequencies as a diagnostic for horizontal mixing in a 3D transport model SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID POLAR VORTEX; POTENTIAL VORTICITY; ISENTROPIC-SIGMA; OZONE LAMINAE; STRATOSPHERE; WINDS AB Ozone simulations are performed in an attempt to simulate laminar events with the frequency observed in balloon ozone sondes. The winds are taken from the Goddard Earth Observing System Data Assimilation System (GEOS DAS); the importance of horizontal and vertical resolution to production of lamina are investigated, A simulation with a high horizontal reolution (grid spacing 1 degrees latitude by 1.25 degrees longitude) and high vertical resolution (similar to 300 m grid spacing) isentropic model produces lamination frequencies close to the balloon sonde climatology near the polar vortex edge but exhibits too much lamination in the subtropics. This indicates that the GEOS DAS winds contain the information to produce laminar events, although such small-scale features are not manifest in the more commonly used 2 degrees latitude by 2.5 degrees longitude transport model, which uses the hybrid sigma-pressure vertical coordinate. The zonal average ozone tendencies due to horizontal mixing in the lamina-producing models are similar to the tendencies in coarser resolution models that show no lamination, suggesting that it is not necessary to resolve laminar events to maintain a realistic ozone budget. The comparison of the modeled lamination frequency with the balloon sonde climatology indicates that the model horizontal mixing at the vortex edge is accurate but in the subtropics the mixing is excessive. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Steve Myers & Associates, Vienna, VA USA. RP Weaver, CJ (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. RI Douglass, Anne/D-4655-2012; Rood, Richard/C-5611-2008 OI Rood, Richard/0000-0002-2310-4262 NR 30 TC 8 Z9 8 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JAN 15 PY 2000 VL 57 IS 2 BP 247 EP 261 DI 10.1175/1520-0469(2000)057<0247:LFAADF>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 276NX UT WOS:000084885300006 ER PT J AU Lakew, B Brasunas, JC Pique, A Fettig, R Mott, B Babu, S Cushman, GM AF Lakew, B Brasunas, JC Pique, A Fettig, R Mott, B Babu, S Cushman, GM TI High-T-c superconducting bolometer on chemically-etched 7 mu m thick sapphire SO PHYSICA C LA English DT Article DE IR detectors; applications of high-T-c superconductors; etched sapphire AB A transition-edge IR detector, using a YBa2Cu3O7-x (YBCO) thin film deposited on a chemically etched 7 mu m thick sapphire substrate has been built. To our knowledge, it is the first such high-T-c superconducting (HTS) bolometer on chemically thinned sapphire. The peak optical detectivity obtained is 1.2 X 10(10) cm Hz(1/2)/W near 4 Hz. Results show that it is possible to obtain high detectivity with thin films on etched sapphire with no processing after the deposition of the YBCO film. We discuss the etching process and its potential for micro-machining sapphire and fabricating two-dimensional detector arrays with suspended sapphire membranes. A 30 mu m thick layer of gold black provided IR absorption. Comparison is made with the current state of the art on silicon substrates. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Neocera, Beltsville, MD 20705 USA. Raytheon Co, Lanham, MD 20706 USA. RP Lakew, B (reprint author), NASA, Goddard Space Flight Ctr, Code 693,Room 142,Bldg 2, Greenbelt, MD 20771 USA. RI brasunas, john/I-2798-2013 NR 11 TC 15 Z9 15 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4534 J9 PHYSICA C JI Physica C PD JAN 15 PY 2000 VL 329 IS 2 BP 69 EP 74 DI 10.1016/S0921-4534(99)00544-4 PG 6 WC Physics, Applied SC Physics GA 273EE UT WOS:000084694300001 ER PT J AU Iliev, MN Litvinchuk, AP Arepalli, S Nikolaev, P Scott, CD AF Iliev, MN Litvinchuk, AP Arepalli, S Nikolaev, P Scott, CD TI Fine structure of the low-frequency Raman phonon bands of single-wall carbon nanotubes SO CHEMICAL PHYSICS LETTERS LA English DT Article ID SCATTERING; MODES AB The Raman spectra of single-wall carbon nanotubes produced by a laser and are process were studied between 5 and 500 K. The linewidth versus temperature dependence of the low-frequency Raman bands between 150 and 200 cm(-1) deviates from that expected for phonon decay through a phonon-phonon scattering mechanism. The experimental results and their analysis provide convincing evidence that each of the low-frequency Raman bands is a superposition of several narrower Raman lines corresponding to tubes of nearly the same diameter. At low temperatures the width Delta(T) = gamma + Gamma(T) of these components is determined mainly by the temperature-independent part gamma approximate to 2 cm(-1). (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Houston, Texas Ctr Superconduct, Houston, TX 77204 USA. Univ Houston, Dept Phys, Houston, TX 77204 USA. Lockheed Martin, GB Tech, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Iliev, MN (reprint author), Univ Houston, Texas Ctr Superconduct, Houston, TX 77204 USA. RI ILIEV, MILKO/A-5941-2008; Arepalli, Sivaram/A-5372-2010; Litvinchuk, Alexander/K-6991-2012; Nikolaev, Pavel/B-9960-2009 OI ILIEV, MILKO/0000-0002-9685-542X; Litvinchuk, Alexander/0000-0002-5128-5232; NR 17 TC 41 Z9 43 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JAN 14 PY 2000 VL 316 IS 3-4 BP 217 EP 221 DI 10.1016/S0009-2614(99)01293-2 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 276PY UT WOS:000084887600008 ER PT J AU Tyuterev, VG Tashkun, SA Schwenke, DW Jensen, P Cours, T Barbe, A Jacon, M AF Tyuterev, VG Tashkun, SA Schwenke, DW Jensen, P Cours, T Barbe, A Jacon, M TI Variational EKE-calculations of rovibrational energies of the ozone molecule from an empirical potential function SO CHEMICAL PHYSICS LETTERS LA English DT Article ID HIGH-RESOLUTION MEASUREMENTS; GROUND-STATE; TRIATOMIC-MOLECULES; WATER MOLECULE; SURFACES; BANDS; SPECTRA; INTENSITIES; DYNAMICS; O-3 AB We report rovibrational calculations from an empirical potential energy surface (PES) of the electronic ground state of ozone, using an Exact Kinetic Energy (EKE) operator. The PES was optimised using the EKE Hamiltonian and experimental spectroscopic high-resolution data. The RMS deviation of calculations for all experimental band centres directly observed so far in high-resolution spectra is 0.12 cm(-1). The RMS deviation of calculations of rotational energies up to J less than or equal to 5 is 0.002 cm(-1) for the (000) level and 0.015 cm(-1) for five lowest vibrational states. Both rotational and vibrational calculations are cm more accurate than presently available EKE-calculations for O-3. The PES shows a physically meaningful long-range behaviour at the dissociation limit. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CNRS, UPRESA Q 6089, UFR Sci, Grp Spect Mol & Atmospher, F-51687 Reims 2, France. Russian Acad Sci, Inst Atmospher Opt, Tomsk 634055, Russia. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Berg Univ Gesamthsch Wuppertal, Theoret Chem FB9, D-42097 Wuppertal, Germany. RP Tyuterev, VG (reprint author), CNRS, UPRESA Q 6089, UFR Sci, Grp Spect Mol & Atmospher, BP 1039, F-51687 Reims 2, France. RI Tashkun, Sergey/E-8682-2014; schwenke, david/I-3564-2013 NR 35 TC 53 Z9 56 U1 0 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JAN 14 PY 2000 VL 316 IS 3-4 BP 271 EP 279 DI 10.1016/S0009-2614(99)01228-2 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 276PY UT WOS:000084887600016 ER PT J AU Bautista, MA AF Bautista, MA TI Electron-impact inner-shell excitation of Fe XVI SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID CLOSE-COUPLING CALCULATIONS; R-MATRIX; ATOMIC DATA; SCATTERING; IONIZATION; LINES AB We report R-matrix calculations of electron-impact collision strengths for excitation from the inner L-shell into doubly excited states of Fe XVI. The basic close-coupling expansion used includes 59 LS terms of the target ion dominated by the configurations 2p(6)3s, 2p(6)3p, 2p(6)3d, 2p(5)3s(2), 2p(5)3s3p, 2p(5)3s3d, 2p(5)3p(2) and 2p(5)3p3d. We investigate the convergence of the collision strengths with the number of partial waves included in the expansion, the contributions from relativistic effects and the convergence of the close-coupling expansion by using pseudo-orbitals that try to account for the effect of the infinite number of levels that lie between the bound and doubly excited states. The present collision strengths exhibit dense packs of high resonances that enhance the effective collision strengths by up to three orders of magnitude. Also important are relativistic effects which alter both the resonance structures and background cross sections, changing the effective collision strengths by up to several orders of magnitude. In addition, a large number of carefully optimized pseudo-orbitals are necessary to achieve convergence in the target expansion. By taking into account the bound states not explicitly included in the expansion, the collision strengths into the doubly excited levels are reduced by up to more than a decade in some cases. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Bautista, MA (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 18 TC 16 Z9 17 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD JAN 14 PY 2000 VL 33 IS 1 BP 71 EP 86 DI 10.1088/0953-4075/33/1/307 PG 16 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 282VA UT WOS:000085239200015 ER PT J AU Rabinowitz, D Helin, E Lawrence, K Pravdo, S AF Rabinowitz, D Helin, E Lawrence, K Pravdo, S TI A reduced estimate of the number of kilometre-sized near-Earth asteroids SO NATURE LA English DT Article AB Near-Earth asteroids are small (diameters < 10 km), rocky bodies with orbits that approach that of the Earth (they come within 1.3 AU Of the Sun). Most have a chance of approximately 0.5% of colliding with the Earth in the next million years. The total number of such bodies with diameters > 1 km has been estimated to be in the range 1,000-2,000, which translates to an approximately 1% chance of a catastrophic collision with the Earth in the next millennium(1,2). These numbers are, however, poorly constrained because of the limitations of previous searches using photographic plates. (One kilometre is below the size of a body whose impact on the Earth would produce global effects(3).) Here we report an analysis of our survey for near-Earth asteroids that uses improved detection technologies. We find that the total number of asteroids with diameters > 1 km is about half the earlier estimates. At the current rate of discovery of near-Earth asteroids, 90% will probably have been detected within the next 20 years. C1 Yale Univ, Dept Phys, New Haven, CT 06511 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Rabinowitz, D (reprint author), Yale Univ, Dept Phys, 266 Whitney Ave,JWG 552, New Haven, CT 06511 USA. EM david.rabinowitz@yale.edu NR 13 TC 91 Z9 93 U1 1 U2 3 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 13 PY 2000 VL 403 IS 6766 BP 165 EP 166 DI 10.1038/35003128 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 275TB UT WOS:000084835300045 PM 10646594 ER PT J AU Kong, AKH Homer, L Kuulkers, E Charles, PA Smale, AP AF Kong, AKH Homer, L Kuulkers, E Charles, PA Smale, AP TI X-ray/optical bursts from GS 1826-24 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; binaries : close; stars : individual : GS 1826-24; X-rays : bursts ID 4U/MXB 1636-53; RAY BURST; NEUTRON STARS AB We report results from the first simultaneous X-ray (RXTE) and optical (SAAO) observations of the low-mass X-ray binary GS 1826-24 in 1998 June. A type I burst was detected in both X-ray and optical wavelengths. Its energy-dependent profile, energetics and spectral evolution provide evidence for an increase in the X-ray burning area but not for photospheric radius expansion. However, we may still derive an upper limit for its distance of 7.5 +/- 0.5 kpc, assuming a peak flux of similar to 2.8 x 10(-8) erg cm(-2) s(-1). A similar to 3-s optical delay with respect to the X-ray burst is also observed, and we infer that this is related to the X-ray reprocessing in the accretion disc. The delay provides additional support for the recently proposed orbital period of similar to 2 h. We also present an ASCA observation from 1998 March, during which two X-ray bursts were detected. C1 Univ Oxford, Dept Astrophys, Nucl & Astrophys Lab, Oxford OX1 3RH, England. Space Res Org Netherlands, NL-3584 CA Utrecht, Netherlands. Univ Utrecht, Inst Astron, NL-3507 TA Utrecht, Netherlands. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kong, AKH (reprint author), Univ Oxford, Dept Astrophys, Nucl & Astrophys Lab, Keble Rd, Oxford OX1 3RH, England. NR 33 TC 44 Z9 44 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JAN 11 PY 2000 VL 311 IS 2 BP 405 EP 413 DI 10.1046/j.1365-8711.2000.03121.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 272UV UT WOS:000084670100019 ER PT J AU Mould, JR Hughes, SMG Stetson, PB Gibson, BK Huchra, JP Freedman, WL Kennicutt, RC Bresolin, F Ferrarese, L Ford, HC Graham, JA Han, MS Hoessel, JG Illingworth, GD Kelson, DD Macri, LM Madore, BF Phelps, RL Prosser, CF Rawson, D Saha, A Sakai, S Sebo, KM Silbermann, NA Turner, AM AF Mould, JR Hughes, SMG Stetson, PB Gibson, BK Huchra, JP Freedman, WL Kennicutt, RC Bresolin, F Ferrarese, L Ford, HC Graham, JA Han, MS Hoessel, JG Illingworth, GD Kelson, DD Macri, LM Madore, BF Phelps, RL Prosser, CF Rawson, D Saha, A Sakai, S Sebo, KM Silbermann, NA Turner, AM TI The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XXI. The Cepheid distance to NGC 1425 SO ASTROPHYSICAL JOURNAL LA English DT Article DE Cepheids; distance scale; galaxies : distances and redshifts galaxies : individual (NGC 1425) ID DISCOVERY; SUPERCLUSTER; CALIBRATION; VARIABLES AB The distance to NGC 1425 has been derived from Cepheid variables, as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen F555W (V) and eight F814W (I) epochs of cosmic-ray-split Wide Field Planetary Camera 2 observations were obtained. Twenty-nine Cepheids were discovered, with periods ranging from 16 to 63 days. Adopting a Large Magellanic Cloud distance modulus and extinction of 18.50 +/- 0.10 mag and E(V-I) = 0.13 mag, respectively, a true reddening-corrected distance modulus (based on an analysis employing the ALLFRAME software package) of 31.73 +/- 0.16 (random) +/- 0.17 (systematic) mag was determined for NGC 1425. The corresponding distance of 22.2 +/- 1.0 (random) +/- 1.0 (systematic) Mpc is in satisfactory agreement with that found with an independent analysis based on the DoPHOT photometry package. C1 Australian Natl Univ, Mt Stromlo & Siding Spring Observ, Res Sch Astron & Astrophys, Inst Adv Studies, Weston, ACT 2611, Australia. Royal Greenwich Observ, Cambridge CB3 0EZ, England. Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Univ Colorado, CASA, Boulder, CO 80309 USA. Harvard Coll, Ctr Astrophys, Cambridge, MA 02138 USA. Observ Carnegie Inst Washington, Pasadena, CA 91101 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. European So Observ, D-85748 Garching, Germany. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Avanti Corp, Fremont, CA 94538 USA. Univ Wisconsin, Madison, WI 53706 USA. Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95064 USA. CALTECH, Ctr Infrared Proc & Anal, Jet Prop Lab, Pasadena, CA 91125 USA. Oberlin Coll, Wright Lab Phys, Oberlin, OH 44074 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. RP Mould, JR (reprint author), Australian Natl Univ, Mt Stromlo & Siding Spring Observ, Res Sch Astron & Astrophys, Inst Adv Studies, Weston, ACT 2611, Australia. RI Gibson, Brad/M-3592-2015 OI Gibson, Brad/0000-0003-4446-3130 NR 30 TC 32 Z9 32 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2000 VL 528 IS 2 BP 655 EP 676 DI 10.1086/308192 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 282GP UT WOS:000085210100010 ER PT J AU Smale, AP Kuulkers, E AF Smale, AP Kuulkers, E TI LMC X-2: The first extragalactic Z source? SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; stars : individual (LMC X-2); stars : neutron; X-rays : stars ID X-RAY BINARIES; QUASI-PERIODIC OSCILLATIONS; K LINE EMISSION; TIMING EXPLORER; SCORPIUS X-1; DISCOVERY; SPECTRA; VARIABILITY; INTENSITY; BEHAVIOR AB during which the source was radiating at a mean intensity near the Eddington limit and was strongly variable on timescales of seconds to hours. The shapes of the X-ray color-color and hardness-intensity diagrams during the observations, the presence of very low frequency noise and high-frequency noise in the power spectra, and the high intrinsic X-ray luminosity of LMC X-2 (which historically spans 0.4-2.0L(Edd) for reasonable estimates of the neutron star mass) are more characteristic of a Z source in its flaring branch than of an atoll source. On this basis, we provisionally reclassify LMC X-2 as a Z source, the eighth such source known and the first to be detected beyond our Galaxy. Using periodogram and Fourier analysis of the X-ray light curve, we detect an apparently significant modulation with a period of 8.160 +/- 0.011 hr and a semiamplitude increasing from 14% in the 1.8-4.0 keV range to 40% at 8.7-19.7 keV. This X-ray modulation appears to confirm a candidate orbital periodicity determined from optical photometry 10 years prior to our campaign, but we cannot rule out a chance alignment of intrinsic X-ray flares, Current RXTE All-Sky Monitor light curves and archival EXOSAT observations show no sign of such a pronounced periodicity. The X-ray spectrum of LMC X-2 can be well ht using variations of simple Comptonization models. Fits to phase (intensity) resolved spectra show strong correlations between the power-law slope (in one parameterization) or the depth to optical scattering (in another) and phase. We discuss the implications of these results for the inclination, geometry, and emitting regions of the LMC X-2 system. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. SRON, NL-3584 CA Utrecht, Netherlands. Univ Utrecht, Astron Inst, NL-3507 TA Utrecht, Netherlands. RP Smale, AP (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 54 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2000 VL 528 IS 2 BP 702 EP 710 DI 10.1086/308193 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 282GP UT WOS:000085210100014 ER PT J AU Baring, MG Jones, FC Ellison, DC AF Baring, MG Jones, FC Ellison, DC TI Inverse bremsstrahlung in shocked astrophysical plasmas SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; cosmic rays; gamma rays : theory; radiation mechanisms : nonthermal; supernova remnants ID HIGH-ENERGY ELECTRONS; INTERPLANETARY SHOCKS; OBLIQUE SHOCKS; COSMIC-RAYS; ACCELERATION; ULYSSES; SCATTERING; INJECTION; PARTICLES; POSITRONS AB There has recently been interest in the role of inverse bremsstrahlung, the emission of photons by fast suprathermal ions in collisions with ambient electrons possessing relatively low velocities, in tenuous plasmas in various astrophysical contexts. This follows a long hiatus in the application of suprathermal ion bremsstrahlung to astrophysical models since the early 1970s. The potential importance of inverse bremsstrahlung relative to normal bremsstrahlung, i.e., where ions are at rest, hinges upon the underlying velocity distributions of the interacting species. Ln this paper, we identify the conditions under which the inverse bremsstrahlung emissivity is significant relative to that for normal bremsstrahlung in shocked astrophysical plasmas. We determine that, since both observational and theoretical evidence favors electron temperatures almost comparable to, and certainly not very deficient relative to, proton temperatures in shocked plasmas, these environments generally render inverse bremsstrahlung at best a minor contributor to the overall emission. Hence, inverse bremsstrahlung can be safely neglected in most models invoking shock acceleration in discrete sources such as supernova remnants. However, on scales greater than or similar to 100 pc distant from these sources, Coulomb collisional losses can deplete the cosmic-ray electrons, rendering inverse bremsstrahlung, and perhaps bremsstrahlung from knock-on electrons, possibly detectable. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. N Carolina State Univ, Dept Phys, Raleigh, NC 27695 USA. NR 67 TC 8 Z9 8 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2000 VL 528 IS 2 BP 776 EP 788 DI 10.1086/308194 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 282GP UT WOS:000085210100020 ER PT J AU Imamura, JN Durisen, RH Pickett, BK AF Imamura, JN Durisen, RH Pickett, BK TI Nonaxisymmetric dynamic instabilities of rotating polytropes. II. Torques, bars, and mode saturation with applications to protostars and fizzlers SO ASTROPHYSICAL JOURNAL LA English DT Article DE black hole physics; binaries : general; hydrodynamics; instabilities; stars : formation; stars : rotation ID NEUTRON STAR DENSITIES; PARTICLE HYDRODYNAMICS; PROTOSTELLAR FORMATION; INTERSTELLAR CLOUDS; EQUILIBRIUM-MODELS; WHITE-DWARF; DISKS; STABILITY; COLLAPSE; EVOLUTION AB Dynamic nonaxisymmetric instabilities in rapidly rotating stars and protostars have a range of potential applications in astrophysics, including implications for binary formation during protostellar cloud collapse and for the possibility of aborted collapse to neutron star densities at late stages of stellar evolution ("fizzlers"). We have recently presented detailed linear analyses for polytropes of the most dynamically unstable global modes, the barlike modes. These produce bar distortions in the regions near the rotation axis but have trailing spiral arms toward the equator. In this paper, we use our linear eigenfunctions to predict the early nonlinear behavior of the dynamic instability and compare these "quasi-linear" predictions with several fully nonlinear hydrodynamics simulations. The comparisons demonstrate that the nonlinear saturation of the barlike instability is due to the self-interaction gravitational torques between the growing central bar and the spiral arms, where angular momentum is transferred outward from bar to arms. We also find a previously unsuspected resonance condition that accurately predicts the mass of the bar regions in our own simulations and in those published by other researchers. The quasi-linear theory makes other accurate predictions about consequences of instability, including properties of possible end-state bars and increases in central density, which can be large under some conditions. We discuss in some detail the application of our results to binary formation during protostellar collapse and to the formation of massive rotating black holes. C1 Univ Oregon, Inst Theoret Sci, Eugene, OR 97403 USA. Univ Oregon, Dept Phys, Eugene, OR 97403 USA. Indiana Univ, Dept Astron, Bloomington, IN 47405 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Imamura, JN (reprint author), Univ Oregon, Inst Theoret Sci, Eugene, OR 97403 USA. EM imamura@herb.uoregon.edu; durisen@cthulhu.astro.indiana.edu; pickett@cosmic.arc.nasa.gov NR 52 TC 33 Z9 33 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2000 VL 528 IS 2 BP 946 EP 964 DI 10.1086/308199 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 282GP UT WOS:000085210100032 ER PT J AU Airapetian, VS Ofman, L Robinson, RD Carpenter, K Davila, J AF Airapetian, VS Ofman, L Robinson, RD Carpenter, K Davila, J TI Winds from luminous late-type stars. I. The effects of nonlinear Alfven waves. SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; stars : individual (alpha Orionis); stars : winds, outflows; supergiants; waves ID LOW-GRAVITY STARS; SOLAR-WIND; STELLAR ATMOSPHERES; GHRS OBSERVATIONS; ALPHA-ORIONIS; MASS-LOSS; COOL; MODELS; PROPAGATION; GENERATION AB We present the results of magnetohydrodynamic (MHD) modeling of winds from luminous late-type stars using a 2.5-dimensional, nonlinear MHD computer code. We assume that the wind is generated within an initially hydrostatic atmosphere and is driven by torsional Alfven waves generated at the stellar surface. Two cases of atmospheric topology are considered: case I has longitudinally uniform density distribution and isotropic radial magnetic field over the stellar surface, and case II has an isotropic, radial magnetic field with a transverse density gradient, which we refer to as an "atmospheric hole." We use the same set of boundary conditions for both models. The calculations are designed to model a cool luminous star, for which we assume an initial hydrostatic pressure scale height of 0.072 R-*, an Alfven wave speed of 92 km s(-1) at the surface, and a wave period of 76 days, which roughly corresponds with the convective turnover time. For case I the calculations produce a wind with terminal velocity of similar to 22 km s(-1) and a mass loss rate comparable to the expected value of 10(-6) M-circle dot yr(-1). For case II we predict a two-component wind: a fast (25 km s(-1)) and relatively dense wind outside of the atmospheric hole and a slow (15 km s(-1)), rarefied wind inside of the hole. C1 NASA, Goddard Space Flight Ctr, Comp Sci Corp, Sci Programs, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. Catholic Univ Amer, Washington, DC 20015 USA. NASA, Goddard Space Flight Ctr, LASP, Greenbelt, MD 20771 USA. RP Airapetian, VS (reprint author), NASA, Goddard Space Flight Ctr, Comp Sci Corp, Sci Programs, Greenbelt, MD 20771 USA. RI Carpenter, Kenneth/D-4740-2012 NR 26 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2000 VL 528 IS 2 BP 965 EP 971 DI 10.1086/308198 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 282GP UT WOS:000085210100033 ER PT J AU Falconer, DA Gary, GA Moore, RL Porter, JG AF Falconer, DA Gary, GA Moore, RL Porter, JG TI An assessment of magnetic conditions for strong coronal heating in solar active regions by comparing observed loops with computed potential field lines SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : magnetic fields; Sun : X-rays, gamma rays AB We report further results on the magnetic origins of coronal heating found from registering coronal images with photospheric vector magnetograms. For two complementary active regions, we use computed potential field lines to examine the global nonpotentiality of bright extended coronal loops and the three-dimensional structure of the magnetic field at their feet, and assess the role of these magnetic conditions in the strong coronal heating in these loops. The two active regions are complementary, in that one is globally potential and the other is globally nonpotential, while each is predominantly bipolar, and each has an island of included polarity in its trailing polarity domain. We find the following: (1) The brightest mainarch loops of the globally potential active region are brighter than the brightest main-arch loops of the globally strongly nonpotential active region. (2) In each active region, only a few of the main-arch magnetic loops are strongly heated, and these are all rooted near the island. (3) The end of each main-arch bright loop apparently bifurcates above the island, so that it embraces the island and the magnetic null above the island. (4) At any one time, there are other main-arch magnetic loops that embrace the island in the same manner as do the bright loops but that are not selected for strong coronal heating. (5) There is continual microflaring in sheared core fields around the island, but the main-arch bright loops show little response to these microflares. From these observational and modeling results we draw the following conclusions: (1) The heating of the main-arch bright loops arises mainly from conditions at the island end of these loops and not from their global nonpotentiality. (2) There is, at most, only a loose coupling between the coronal heating in the bright loops of the main arch and the coronal heating in the sheared core fields at their feet, although in both the heating is driven by conditions/events in and around the island. (3) The main-arch bright loops are likely to be heated via reconnection driven at the magnetic null over the island. The details of how and where (along the null line) the reconnection is driven determine which of the split-end loops are selected for strong heating. (4) The null does not appear to be directly involved in the heating of the sheared core fields or in the heating of an extended loop rooted in the island. Rather, these all appear to be heated by microflares in the sheared core field. C1 Univ Alabama, Tuscaloosa, AL 35487 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Falconer, DA (reprint author), NASA, George C Marshall Space Flight Ctr, SD50, Huntsville, AL 35812 USA. NR 11 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2000 VL 528 IS 2 BP 1004 EP 1014 DI 10.1086/308188 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 282GP UT WOS:000085210100039 ER PT J AU Raines, SN Watson, DM Pipher, JL Forrest, WJ Greenhouse, MA Satyapal, S Woodward, CE Smith, HA Fischer, J Goetz, JA Frank, A AF Raines, SN Watson, DM Pipher, JL Forrest, WJ Greenhouse, MA Satyapal, S Woodward, CE Smith, HA Fischer, J Goetz, JA Frank, A TI Large proper-motion infrared [Fe II] emission-line features in GGD 37 SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : general; ISM : Herbig-Haro objects; ISM : individual (GGD 37); ISM : jets and outflows; stars : formation ID HERBIG-HARO OBJECTS; STAR-FORMATION REGION; CEPHEUS-A; FORMING REGION; OUTFLOWS; CEP AB We report the detection of proper motions in [Fe Ir] 1.644 mu m emission among the southeasternmost features in the Herbig-Haro object complex GGD 37. Imaging observations were made over a period of 5 yr, at epochs 1993.67, 1996.71, and 1998.68, that reveal proper-motion velocities of 400 +/- 200 km s(-1) at GGD 37:W2 and 850 +/- 200 km s(-1) at a newly identified object, designated GGD 37:RWPF 1. We believe the proper-motion velocity of GGD 37:RWPF 1 is the highest found to date for a Herbig-Haro object. The direction of GGD 37: RWPF 1's proper motion is almost due west, away from the nearby young stellar object complex in Cep A East. GGD 37:W2's direction of proper motion is north/northwest, which does not lead back to any of the compact objects in Cep A East. C1 Univ Rochester, Dept Phys & Astron, Rochester, NY 14627 USA. Univ Rochester, CEK Mees Observ, Rochester, NY 14627 USA. Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Wyoming, Wyoming Infrared Observ, Dept Phys & Astron, Laramie, WY 82071 USA. Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. USN, Res Lab, Remote Sensing Div, Washington, DC 20375 USA. Coll Wooster, Dept Phys, Wooster, OH 44691 USA. RP Raines, SN (reprint author), Univ Rochester, Dept Phys & Astron, 601 Elmwood Ave, Rochester, NY 14627 USA. NR 35 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2000 VL 528 IS 2 BP L115 EP L118 DI 10.1086/312427 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 282GW UT WOS:000085210700015 ER PT J AU Malik, M Noor, AK AF Malik, M Noor, AK TI Accurate determination of transverse normal stresses in hybrid laminated panels subjected to electro-thermo-mechanical loadings SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article DE interlaminar transverse stresses; hybrid composite piezoelectric panels; smart structures; differential quadrature method ID SHEAR DEFORMATION-THEORY; FINITE-ELEMENT; PLATES AB A computational procedure is presented for the accurate determination of transverse normal stresses in hybrid laminated panels consisting of fibre-reinforced composite and:piezoelectric layers, and subjected to mechanical, thermal and electrical loadings. The three key elements of the procedure are: (a) using through-the-thickness distributions of the response quantities of a simpler problem to effect a dimensional reduction in the given problem, (b) adaptive improvement of the thickness distributions of the response quantities through successive applications of the Rayleigh-Ritz technique, in conjunction with the three-dimensional electro-thermo-elasticity equations for each layer, and (c) using three-dimensional divergence equations for evaluating the transverse stresses and the transverse component of the electric field. The effectiveness of the procedure is demonstrated by means of two numerical examples of rectangular, hybrid laminated panels. The panels had two opposite edges clamped and the other two either simply supported or clamped. In both cases, the simpler panels were the panels of the same lamination and geometry as the example problems, but with all edges simply supported. Published in 2000 by John Wiley & Sons, Ltd. C1 Univ Virginia, NASA, Langley Res Ctr, Ctr Adv Computat Technol, Hampton, VA 23681 USA. RP Noor, AK (reprint author), Univ Virginia, NASA, Langley Res Ctr, Ctr Adv Computat Technol, Mailstop 201, Hampton, VA 23681 USA. NR 21 TC 8 Z9 9 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD JAN 10 PY 2000 VL 47 IS 1-3 BP 477 EP 495 DI 10.1002/(SICI)1097-0207(20000110/30)47:1/3<477::AID-NME780>3.0.CO;2-M PG 19 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA 276FG UT WOS:000084864500023 ER PT J AU Patnaik, SN Coroneos, RM Hopkins, DA AF Patnaik, SN Coroneos, RM Hopkins, DA TI Compatibility conditions of structural mechanics SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article DE compatibility conditions; finite element method; integrated force method; structures; elasticity ID INTEGRATED FORCE METHOD; FINITE-ELEMENT ANALYSIS; CONSTRAINTS; CONTINUUM; STRESS AB The theory of elasticity has camouflaged a glitch in the compatibility formulation since 1860. In structures the ad hoc compatibility conditions through virtual 'cuts' and closing 'gaps' is not parallel to the strain formulation in elasticity. The deficiency in the compatibility condition has prevented the development of direct stress determination method in structures and in elasticity. We have addressed and attempted to unify the theory of compatibility. This has lead to the development of the Integrated Force Method for structures and the Completed Beltrami-Michell's Formulation in elasticity. The utilization of the compatibility conditions allows mapping of variables and facile movement among different structural analysis formulations. This paper reviews and illustrates the requirement of compatibility in structures and in elasticity. Addresses the generation of the conditions and quantifies the benefit of their use. The traditional analysis methods and available solutions should be verified for compliance of the compatibility conditions. Published in 2000 by John Wiley & Sons, Ltd. C1 Ohio Aerosp Inst, Brook Pk, OH 44142 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Patnaik, SN (reprint author), Ohio Aerosp Inst, 22800 Cedar Point Rd, Brook Pk, OH 44142 USA. NR 27 TC 8 Z9 9 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD JAN 10 PY 2000 VL 47 IS 1-3 BP 685 EP 704 DI 10.1002/(SICI)1097-0207(20000110/30)47:1/3<685::AID-NME788>3.3.CO;2-P PG 22 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA 276FG UT WOS:000084864500031 ER PT J AU Eckardt, FD Wilkinson, MJ Lulla, KP AF Eckardt, FD Wilkinson, MJ Lulla, KP TI Cover - Using digitized handheld Space Shuttle photography for terrain visualization SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article C1 Univ Botswana & Swaziland, Dept Environm Sci, Gaborone, Botswana. NASA, Lyndon B Johnson Space Ctr, Off Earth Sci, Houston, TX 77058 USA. RP Eckardt, FD (reprint author), Univ Botswana & Swaziland, Dept Environm Sci, Private Bag 0022, Gaborone, Botswana. RI Eckardt, Frank/N-3682-2015 OI Eckardt, Frank/0000-0003-0200-7110 NR 3 TC 4 Z9 4 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JAN 10 PY 2000 VL 21 IS 1 BP 1 EP 5 DI 10.1080/014311600210948 PG 5 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 272ZP UT WOS:000084681600001 ER PT J AU Herwitz, SR Sandler, B Slye, RE AF Herwitz, SR Sandler, B Slye, RE TI Twenty-one years of crown area change in the Jasper Ridge Biological Preserve based on georeferenced multitemporal aerial photographs SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID RAIN-FOREST; GROWTH-RATES; INFORMATION-SYSTEMS; SPECIES COMPOSITION; INDIVIDUAL PLANT; CANOPY DYNAMICS; NEW-ENGLAND; POPULATION; MORTALITY; TREES AB A time series of large-scale aerial photographs of a 25 ha section of the Jasper Ridge Biological Preserve (JRBP) in California was analysed for the quantification of long-term changes in the orthogonally projected crown areas of a sample of mature canopy trees growing in closed woodland and open grassland habitats. Crown area changes were computed on the basis of pairwise image comparisons for the years 1974, 1980, 1988, 1989, 1990, 1991, 1993 and 1995. Single frame image correction methods were assessed by comparing a high-resolution physical-system based method of photogrammetric orthorectification with a low-resolution method of georeferencing that involved the use of ground control points (GCPs) for the derivation of best-fit statistical transformations. The same crown digitization procedure was used for both methods, and a statistically significant difference was not found between the high-resolution and low-resolution measured crown areas. Crown area changes were not correlated with differences in sun position at the time of aerial photo acquisition nor with differences in the off-nadir distances of each crown in the images being compared. The upper limit of digitizing error was 3.5% based on the mean coefficient of variation plus one standard deviation computed from repeat digitization measures of each crown. Crown area changes exceeding 3.5% in the pairwise image comparisons were attributed to actual crown growth or crown reduction. Expressed as a percentage of the original crown area, the mean annual rate of change for each pairwise sample period was 4.9% yr(-1). In absolute terms, the mean annual rate of crown area change over the 21-year period 1974-1995 was 1.4m(2) yr(-1). The long-term mean annual crown growth rate of the clustered woodland trees (1.3m(2) yr(-1)) was not significantly different from the isolated grassland trees (1.5m(2) yr(-1)). The mean annual rates of change for the periods 1974-1980, 1980-1989 and 1991-1993 were similar to the long-term average. Unusually low mean growth rates characterized the drought years of 1989-1990 and 1990-1991, while the relatively wet period of 1993-1995 exhibited the most dramatic increase in crown area at a mean rate of 3.0m(2) yr(-1). C1 Clark Univ, Grad Sch Geog, Worcester, MA 01610 USA. Clark Univ, Dept Biol, Worcester, MA 01610 USA. Stanford Univ, GIS Lab, Ctr Conservat Biol, Dept Sci Biol, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Ecosyst Sci & Technol Branch, Moffett Field, CA 94035 USA. RP Herwitz, SR (reprint author), Clark Univ, Grad Sch Geog, Worcester, MA 01610 USA. NR 48 TC 4 Z9 6 U1 2 U2 8 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JAN 10 PY 2000 VL 21 IS 1 BP 45 EP 60 DI 10.1080/014311600210984 PG 16 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 272ZP UT WOS:000084681600005 ER PT J AU Giglio, L Kendall, JD Tucker, CJ AF Giglio, L Kendall, JD Tucker, CJ TI Remote sensing of fires with the TRMM VIRS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB Although the Visible and Infrared Scanner (VIRS) instrument on board the Tropical Rainfall Measuring Mission (TRMM) satellite is designed primarily to study precipitation, it offers a new opportunity for the remote sensing of fire activity in regions within +/- 40 degrees of the equator. VIRS is a five-channel imaging spectroradiometer with bands ranging from 0.6 to 12 mu m. Its similarity to the Advanced Very High Resolution Radiometer (AVHRR), which has operated since 1978 on board the National Oceanic and Atmospheric Administration (NOAA) satellite series, is no coincidence, as a primary objective of VIRS is to provide an important link between TRMM precipitation measurements and those derived from other current and historical satellite sensors. The similarity of the VIRS infrared bands, in particular, to those of AVHRR provides a foundation for fire detection, which has been clearly demonstrated for AVHRR. However, VIRS offers some additional capabilities which should enable it to make an important contribution to the remote sensing of fire. C1 NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Giglio, L (reprint author), NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Code 923, Greenbelt, MD 20771 USA. NR 12 TC 47 Z9 48 U1 1 U2 4 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JAN 10 PY 2000 VL 21 IS 1 BP 203 EP 207 DI 10.1080/014311600211109 PG 5 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 272ZP UT WOS:000084681600017 ER PT J AU Jacqmin, D AF Jacqmin, D TI Contact-line dynamics of a diffuse fluid interface SO JOURNAL OF FLUID MECHANICS LA English DT Article ID BOUNDARY-CONDITIONS; MOLECULAR-DYNAMICS; 2-PHASE FLUID; FLOW; SOLIDS; MODEL; SIMULATIONS; SURFACE; LIQUIDS; ORDER AB An investigation is made into the moving contact line dynamics of a Cahn-Hilliard-van der Waals (CHW) diffuse mean-field interface. The interface separates two incompressible viscous fluids and can evolve either through convection or through diffusion driven by chemical potential gradients. The purpose of this paper is to show how the CHW moving contact line compares to the classical sharp interface contact line. It therefore discusses the asymptotics of the CHW contact line velocity and chemical potential fields as the interface thickness epsilon and the mobility kappa both go to zero. The CHW and classical velocity fields have the same outer behaviour but can have very different inner behaviours and physics. In the CHW model, wall-liquid bonds are broken by chemical potential gradients instead of by shear and change of material at the wall is accomplished by diffusion rather than convection. The result is, mathematically at least, that the CHW moving contact line can exist even with no-slip conditions for the velocity. The relevance and realism or lack thereof of this is considered through the course of the paper. The two contacting fluids are assumed to be Newtonian and, to a first approximation, to obey the no-slip condition. The analysis is linear. For simplicity most of the analysis and results are for a 90 degrees contact angle and for the fluids having equal dynamic viscosity mu and mobility kappa. There are two regions of flow. To leading order the outer-region velocity field is the same as for sharp interfaces (flow field independent of r) while the chemical potential behaves like r(-xi), xi = pi/2/max{theta(eq), pi - theta(eq)}, theta(eq) being the equilibrium contact angle. An exception to this occurs for theta(eq) = 90 degrees, when the chemical potential behaves like ln r/r. The diffusive and viscous contact line singularities implied by these outer solutions are resolved in the inner region through chemical diffusion. The length scale of the inner region is about 10 root mu kappa -typically about 0.5-5 nm. Diffusive fluxes in this region are O(1). These counterbalance the effects of the velocity, which, because of the assumed no-slip boundary condition, fluxes material through the interface in a narrow boundary layer next to the wall. The asymptotic analysis is supplemented by both linearized and nonlinear finite difference calculations, These are made at two scales, experimental and nanoscale. The first set is done to show CHW interface behaviour and to test the qualitative applicability of the CHW model and its asymptotic theory to practical computations of experimental scale, nonlinear, low capillary number hows. The nanoscale calculations are carried out with realistic interface thicknesses and diffusivities and with various assumed levels of shear-induced slip. These are discussed in an attempt to evaluate the physical relevance of the CHW diffusive model. The various asymptotic and numerical results together indicate a potential usefullness for the CHW model for calculating and modelling wetting and dewetting flows. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 45 TC 311 Z9 313 U1 8 U2 72 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 EI 1469-7645 J9 J FLUID MECH JI J. Fluid Mech. PD JAN 10 PY 2000 VL 402 BP 57 EP 88 DI 10.1017/S0022112099006874 PG 32 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 281LL UT WOS:000085161800003 ER PT J AU Halicioglu, T AF Halicioglu, T TI Calculation of energy barriers for the chlorine etching of Si(100) surface with step edges SO SURFACE SCIENCE LA English DT Letter DE chlorine; etching; silicon; step edges ID MOLECULAR-DYNAMICS SIMULATIONS; FIRST-PRINCIPLES; ADSORPTION; SILICON; DESORPTION; SI AB Calculations were carried out to determine energies and barriers involved in the chlorination process of Si(100) (2 x 1) surfaces and in the subsequent desorption of Si-containing species. First and second chlorination steps for Si atoms located at step edge sites were investigated. Energy calculations for exposed terraces include extremely low and high surface Cl concentrations. No energy barriers were found for the first chlorination step, which also displayed little or no dependence on the surface chlorine concentration. However, the second chlorination step (leading to the formation of an attached -SiCl2 unit) involves a barrier, and calculated energetics depend on the Cl concentration of the terraces. One of the important outcomes of this study is related to the composition and the structure of the exposed surfaces. Results strongly indicate that the role played by surface defects and by the attached Cl concentration (in the vicinity of the adsorption sites) on reaction energetics is significant. They influence local reactions and, in turn, affect the overall etching process. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Thermosci Inst, Moffett Field, CA 94035 USA. RP Halicioglu, T (reprint author), Dept Mat Sci & Engn, Stanford, CA 94305 USA. NR 17 TC 5 Z9 5 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD JAN 10 PY 2000 VL 445 IS 1 BP L53 EP L57 DI 10.1016/S0039-6028(99)01064-X PG 5 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 275ZK UT WOS:000084850500007 ER PT J AU Ma, Q Tipping, RH AF Ma, Q Tipping, RH TI The density matrix of H2O-N-2 in the coordinate representation: A Monte Carlo calculation of the far-wing line shape SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID WATER CONTINUUM ABSORPTION; ROTATIONAL BANDS; MOLECULES AB The far-wing line shape theory within the binary collision and quasistatic framework has been developed using the coordinate representation. Within this formalism, the main computational task is the evaluation of multidimensional integrals whose variables are the orientational angles needed to specify the initial and final positions of the system during transition processes. Using standard methods, one is able to evaluate the seven-dimensional integrations required for linear molecular systems, or the seven-dimensional integrations for more complicated asymmetric-top (or symmetric-top) molecular systems whose interaction potential contains cyclic coordinates. In order to obviate this latter restriction on the form of the interaction potential, a Monte Carlo method is used to evaluate the nine-dimensional integrations required for systems consisting of one asymmetric-top (or symmetric-top) and one linear molecule, such as H2O-N-2. Combined with techniques developed previously to deal with sophisticated potential models, one is able to implement realistic potentials for these systems and derive accurate, converged results for the far-wing line shapes and the corresponding absorption coefficients. Conversely, comparison of the far-wing absorption with experimental data can serve as a sensitive diagnostic tool in order to obtain detailed information on the short-range anisotropic dependence of interaction potentials. (C) 2000 American Institute of Physics. [S0021-9606(00)00802-3]. C1 Columbia Univ, Dept Appl Phys, New York, NY 10025 USA. NASA, Inst Space Studies, Goddard Space Flight Ctr, New York, NY 10025 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. RP Ma, Q (reprint author), Columbia Univ, Dept Appl Phys, New York, NY 10025 USA. NR 20 TC 28 Z9 30 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JAN 8 PY 2000 VL 112 IS 2 BP 574 EP 584 DI 10.1063/1.480550 PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 269ZB UT WOS:000084507000011 ER PT J AU Greenblatt, BJ Zanni, MT Neumark, DM AF Greenblatt, BJ Zanni, MT Neumark, DM TI Femtosecond photoelectron spectroscopy of I-2(-)(CO2)(n) clusters (n=4, 6, 9, 12, 14, 16) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID NONADIABATIC MOLECULAR-DYNAMICS; GEMINATE RECOMBINATION DYNAMICS; VIBRATIONAL-RELAXATION; CHARGE FLOW; SOLVENT DYNAMICS; PHOTODISSOCIATION; IONS; I-2(-); I2; I-2(-)CENTER-DOT-AR-N AB The photodissociation dynamics of I-2(-)(CO2)(n)(n=4-16) clusters excited at 780 nm have been studied with femtosecond photoelectron spectroscopy (FPES). The range of cluster sizes spans the uncaged and fully-caged product limits for this reaction. We observe time scales for a variety of processes in these clusters, including dissociation of the I-2(-) chromophore, solvation of the I- fragment, the onset of recombination on the ground state of I-2(-), vibrational relaxation, and solvent evaporation. In addition, substantial trapping in a "solvent-separated" state is seen for clusters with n greater than or equal to 9; this state persists for at least 200 ps, the longest time delay probed here. Simulations of the spectra were performed in order to determine the time dependence of the electronic state populations, the I-2(-) vibrational distribution, and the number of CO2 molecules in the cluster. Results are compared to previous experimental and theoretical studies of I-2(-)(CO2)(n) photodissociation, and to a recent FPES study of I-2(-)(Ar)(n) clusters. (C) 2000 American Institute of Physics. [S0021-9606(00)00102-1]. C1 Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Div Chem Sci, Berkeley, CA 94720 USA. RP Greenblatt, BJ (reprint author), NASA, Ames Res Ctr, Atmospher Chem & Dynam Branch, Mail Stop 245-5, Moffett Field, CA 94035 USA. RI Zanni, Martin/K-2707-2013; Neumark, Daniel/B-9551-2009 OI Neumark, Daniel/0000-0002-3762-9473 NR 43 TC 35 Z9 35 U1 1 U2 8 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JAN 8 PY 2000 VL 112 IS 2 BP 601 EP 612 DI 10.1063/1.480685 PG 12 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 269ZB UT WOS:000084507000014 ER PT J AU Drouin, BJ Dannemiller, JJ Kukolich, SG AF Drouin, BJ Dannemiller, JJ Kukolich, SG TI The gas-phase structure of chloroferrocene from microwave spectra SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID COUPLING PARAMETERS; SPECTROSCOPY; FERROCENES AB Rotational spectra for ten isotopomers of chloroferrocene were measured using pulsed-beam Fourier transform microwave spectroscopy. Rotational transitions due to both "a" and "b" dipole moments were measured in the 4-12 GHz range. Thirty rotational constants were determined from microwave data for the normal, Fe-54, Fe-57, Cl-37, and six unique C-13 isotopomers, by fitting the microwave data using a rigid rotor Hamiltonian with centrifugal distortion and quadrupole coupling terms. The moments of inertia of the isotopomers were used in Kraitchman and in least-squares fitting analyses to determine gas-phase structural parameters. The unsubstituted cyclopentadienyl (C5H5) ligand was determined to have essentially fivefold local symmetry, while the chlorinated cyclopentadienyl ligand shows small, but significant distortions from the fivefold symmetry. The C-Cl bond is bent 2.7(6)degrees from the plane of carbon atoms. This substituted C5H4Cl ligand is tilted 1.4(5)degrees with respect to the unsubstituted C5H5 ligand. The carbon atoms of the two cyclopentadienyl ligands are eclipsed, similar to normal ferrocene. The average Fe-C distance is 2.042(9) Angstrom. The estimated displacement of C-H bonds out of the planes of the carbon atoms is 4(2)degrees away from the metal atom. (C) 2000 American Institute of Physics. [S0021-9606(00)01002-3]. C1 Univ Arizona, Dept Chem, Tucson, AZ 85721 USA. RP Drouin, BJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 8 Z9 8 U1 1 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JAN 8 PY 2000 VL 112 IS 2 BP 747 EP 751 DI 10.1063/1.480708 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 269ZB UT WOS:000084507000029 ER PT J AU Litvin, FL De Donno, M Peng, A Vorontsov, A Handschuh, RF AF Litvin, FL De Donno, M Peng, A Vorontsov, A Handschuh, RF TI Integrated computer program for simulation of meshing and contact of gear drives SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article ID SPIRAL BEVEL GEARS; IMPROVED GEOMETRY; GENERATION; DESIGN AB The authors propose an integrated Tooth Contact Analysis (TCA) computer program for simulation of meshing and contact of gear drives that enables to determine transmission errors and shift of bearing contact for misaligned gear drives. The developed computer program combines numerical solutions for the problems above and their graphical interpretation. The program is applicable for various gear dl ives but needs derivation of tooth surface equations specified for the considered gear drive. The computer program represents a set of integrated operations such as the development of required algorithms, storing in database, copying, deleting, printing, design correction from the database, etc. The proposed computer program is based on application of the Java programming language, Examples of application for a spiral bevel gear drive and a worm gear drive are provided. (C) 2000 Elsevier Science S.A. All rights reserved. C1 Univ Illinois, Dept Mech Engn MC 251, Gear Res Lab, Chicago, IL 60607 USA. NASA, Lewis Res Ctr, Army Res Lab, Vehicle Technol Ctr, Cleveland, OH 44135 USA. RP Litvin, FL (reprint author), Univ Illinois, Dept Mech Engn MC 251, Gear Res Lab, 2039 Engn Res Facil,842 W Taylor St, Chicago, IL 60607 USA. NR 17 TC 24 Z9 37 U1 1 U2 5 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0045-7825 J9 COMPUT METHOD APPL M JI Comput. Meth. Appl. Mech. Eng. PD JAN 7 PY 2000 VL 181 IS 1-3 BP 71 EP 85 DI 10.1016/S0045-7825(99)00068-7 PG 15 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA 276PX UT WOS:000084887500004 ER PT J AU Bartel, N Bietenholz, MF Rupen, MP Beasley, AJ Graham, DA Altunin, VI Venturi, T Umana, G Cannon, WH Conway, JE AF Bartel, N Bietenholz, MF Rupen, MP Beasley, AJ Graham, DA Altunin, VI Venturi, T Umana, G Cannon, WH Conway, JE TI The changing morphology and increasing deceleration of supernova 1993J in M81 SO SCIENCE LA English DT Article ID SN 1993J; GALAXY M81; RADIO; SN-1993J; EXPANSION; SUPERGIANT; DISCOVERY; DISTANCE; SN1993J; EJECTA AB Twenty consecutive Very Long Baseline Interferometry images of supernova 1993J from the time of explosion to the present show the dynamic evolution of the expanding radio shell of an exploded star. High-precision astrometry reveals that the supernova expands isotropically from its explosion center. Systematic changes in the images may reflect a pattern of anisotropies and inhomogeneities in the material left over from the progenitor star. As the shock front sweeps up the material in the surrounding medium, it is increasingly decelerated and influenced by the material. After 5 years, the supernova has slowed to half of its original expansion velocity and may have entered the early stages of the adiabatic phase common in much older supernova remnants in the Milky Way Galaxy. C1 York Univ, Dept Phys & Astron, Toronto, ON M3J 1P3, Canada. Natl Radio Astron Observ, Socorro, NM 87801 USA. Max Planck Inst Radioastron, D-53121 Bonn, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CNR, Inst Radioastron, I-40129 Bologna, Italy. CNR, Inst Radioastron, I-96017 Noto, Italy. Space Geodynam Lab CRESTech, Toronto, ON M3J 3K1, Canada. Chalmers, Onsala Space Observ, S-43992 Onsala, Sweden. RP York Univ, Dept Phys & Astron, Toronto, ON M3J 1P3, Canada. EM bartel@york.u.ca NR 35 TC 49 Z9 49 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 EI 1095-9203 J9 SCIENCE JI Science PD JAN 7 PY 2000 VL 287 IS 5450 BP 112 EP 116 DI 10.1126/science.287.5450.112 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 271DG UT WOS:000084578400047 ER PT J AU Gawronski, W Sawicki, JT AF Gawronski, W Sawicki, JT TI Structural damage detection using modal norms SO JOURNAL OF SOUND AND VIBRATION LA English DT Letter C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Cleveland State Univ, Dept Mech Engn, Cleveland, OH 44115 USA. RP Gawronski, W (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 34 Z9 38 U1 0 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD JAN 6 PY 2000 VL 229 IS 1 BP 194 EP 198 DI 10.1006/jsvi.1999.2179 PG 5 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 272YX UT WOS:000084680000009 ER PT J AU Scholin, CA Gulland, F Doucette, GJ Benson, S Busman, M Chavez, FP Cordaro, J DeLong, R De Vogelaere, A Harvey, J Haulena, M Lefebvre, K Lipscomb, T Loscutoff, S Lowenstine, LJ Marin, R Miller, PE McLellan, WA Moeller, PDR Powell, CL Rowles, T Silvagni, P Silver, M Spraker, T Trainer, V Van Dolah, FM AF Scholin, CA Gulland, F Doucette, GJ Benson, S Busman, M Chavez, FP Cordaro, J DeLong, R De Vogelaere, A Harvey, J Haulena, M Lefebvre, K Lipscomb, T Loscutoff, S Lowenstine, LJ Marin, R Miller, PE McLellan, WA Moeller, PDR Powell, CL Rowles, T Silvagni, P Silver, M Spraker, T Trainer, V Van Dolah, FM TI Mortality of sea lions along the central California coast linked to a toxic diatom bloom SO NATURE LA English DT Article ID DOMOIC ACID; HIPPOCAMPAL DAMAGE; PROBES; MICE AB Over 400 California sea lions (Zalophus californianus) died and many others displayed signs of neurological dysfunction along the central California coast during May and June 1998. A bloom of Pseudo-nitzschia australis (diatom) was observed in the Monterey Bay region during the same period. This bloom was associated with production of domoic acid (DA), a neurotoxin(1) that was also detected in planktivorous fish, including the northern anchovy (Engraulis mordax), and in sea lion body fluids. These and other concurrent observations demonstrate the trophic transfer of DA resulting in marine mammal mortality. In contrast to fish, blue mussels (Mytilus edulus) collected during the DA outbreak contained no DA or only trace amounts. Such findings reveal that monitoring of mussel toxicity alone does not necessarily provide adequate warning of DA entering the food web at levels sufficient to harm marine wildlife and perhaps humans. C1 Monterey Bay Aquarium Res Inst, Moss Landing, CA 95039 USA. Marin Headlands, Marine Mammal Ctr, Sausalito, CA 94965 USA. Natl Ocean Serv, Marine Biotoxins Program, NOAA, Charleston, SC 29412 USA. Moss Landing Marine Labs, Moss Landing, CA 95039 USA. Natl Marine Fisheries Serv, Long Beach, CA 90802 USA. Natl Marine Mammal Lab, Seattle, WA 98115 USA. Monterey Bay Natl Marine Sanctuary, Monterey, CA 93940 USA. Univ Calif Santa Cruz, Inst Marine Sci, Santa Cruz, CA 95064 USA. Armed Forces Inst Pathol, Washington, DC 20306 USA. Calif Dept Hlth Serv, Food & Drug Branch, Sacramento, CA 94234 USA. Univ Calif Davis, Dept Pathol Microbiol & Immunol, Davis, CA 95616 USA. Univ N Carolina, Wilmington, NC 28403 USA. Natl Marine Fisheries Serv, Silver Spring, MD 20910 USA. Colorado State Univ, Coll Vet Med, Ft Collins, CO 80523 USA. Natl Marine Fisheries Serv, NOAA, ECD, Seattle, WA 98112 USA. RP Scholin, CA (reprint author), Monterey Bay Aquarium Res Inst, 770 Sandholdt Rd, Moss Landing, CA 95039 USA. RI Doucette, Gregory/M-3283-2013 NR 27 TC 425 Z9 444 U1 6 U2 105 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 6 PY 2000 VL 403 IS 6765 BP 80 EP 84 DI 10.1038/47481 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 273BM UT WOS:000084687400046 PM 10638756 ER PT J AU Watson, AB AF Watson, AB TI Visual detection of spatial contrast patterns: Evaluation of five simple models. SO OPTICS EXPRESS LA English DT Article ID SENSITIVITY; MASKING; VISION AB The ModelFest Phase One dataset is a collection of luminance contrast thresholds for 43 two-dimensional monochromatic spatial patterns confined to an area of approximately two by two degrees. These data were collected by a collaboration among twelve laboratories, and were designed to provide a common database for calibration and testing of spatial vision models. Here I report fits of the ModelFest data with five models: Peak Contrast, Contrast Energy, Generalized Energy, a Gabor Channels model, and a Discrete Cosine Transform model. The Gabor Channels model provides the best fit, though the other, simpler models, with the exception of Peak Contrast, provide remarkably good fits as well. Though there are clear individual differences, regularities in the data suggest the possibility of constructing a standard observer for spatial vision. (C) 2000 Optical Society of America. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Watson, AB (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 25 TC 65 Z9 65 U1 3 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1094-4087 J9 OPT EXPRESS JI Opt. Express PD JAN 3 PY 2000 VL 6 IS 1 BP 12 EP 33 PG 22 WC Optics SC Optics GA 271FA UT WOS:000084582500004 PM 12238521 ER PT S AU Froggatt, M Childers, B Moore, J Erdogan, T AF Froggatt, M Childers, B Moore, J Erdogan, T BE Mignani, AG Lefevre, HC TI High density strain sensing using optical frequency domain reflectometry SO 14TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 14th International Conference on Optical Fiber Sensors CY OCT 11-13, 2000 CL VENICE, ITALY SP CNR ARF, CNR IROE, IIC, Assoc Elettrotecn & Elettron Italiana, Assoc Italiana Sensori & Microsistemi, European Opt Soc, Opt Soc Amer, Soc Italiana Ott & Foton, IEE, IOP, SPIE ID PULSE BRAGG GRATINGS; FIBER AB A system for producing and demultiplexing large numbers of fiber Bragg grating sensors is described. Three thousand gratings were multiplexed in four optical fibers and demonstrated on a large test article. Preliminary results of a strain sensing system in unaltered fiber-using OFDR measurements of the Rayleigh scatter is also described. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Froggatt, M (reprint author), NASA, Langley Res Ctr, MS 231, Hampton, VA 23681 USA. NR 8 TC 6 Z9 6 U1 0 U2 2 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3848-0 J9 P SOC PHOTO-OPT INS PY 2000 VL 4185 BP 249 EP 255 PG 7 WC Optics; Physics, Applied SC Optics; Physics GA BR74S UT WOS:000167396300064 ER PT B AU Houser, PR Cosgrove, BA Entin, JK Lettenmaier, D O'Donnell, G Mitchell, K Marshall, C Lohmann, D Schaake, JC Duan, Q Wood, E Habets, F AF Houser, PR Cosgrove, BA Entin, JK Lettenmaier, D O'Donnell, G Mitchell, K Marshall, C Lohmann, D Schaake, JC Duan, Q Wood, E Habets, F GP AMS AMS TI Short-term retrospective Land Data Assimilation Schemes SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc ID MODELS; PARAMETERIZATION; IMPACT C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Houser, PR (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Houser, Paul/J-9515-2013 OI Houser, Paul/0000-0002-2991-0441 NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 7 EP 10 PG 4 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100003 ER PT B AU Bosilovich, MG Schubert, S Molod, A Takacs, LL AF Bosilovich, MG Schubert, S Molod, A Takacs, LL GP AMS AMS TI Precipitation recycling in the NASA GEOS Data Assimilation System SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, USRA, DAO, Greenbelt, MD 20771 USA. RP Bosilovich, MG (reprint author), NASA, USRA, DAO, Code 901-3, Greenbelt, MD 20771 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 15 EP 17 PG 3 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100005 ER PT B AU Entin, JK Houser, P Cosgrove, BA Choudhury, B Wang, J AF Entin, JK Houser, P Cosgrove, BA Choudhury, B Wang, J GP AMS AMS TI Using data assimilation of TRMM passive microwave observations to improve land surface modeling SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc ID SOIL-MOISTURE C1 NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Greenbelt, MD 20771 USA. RP Entin, JK (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Mail Code 974, Greenbelt, MD 20771 USA. RI Houser, Paul/J-9515-2013 OI Houser, Paul/0000-0002-2991-0441 NR 2 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 61 EP 62 PG 2 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100018 ER PT B AU Gu, JJ Smith, EA AF Gu, JJ Smith, EA GP AMS AMS TI Improvements in wintertime GOES SRB retrievals for hydrometeorological modeling of large scale BOREAS domain SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, UAH, Global Hydrol & Climate Ctr, Huntsville, AL 35899 USA. RP Smith, EA (reprint author), NASA, UAH, Global Hydrol & Climate Ctr, 977 Explorer Blvd, Huntsville, AL 35899 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 185 EP 185 PG 1 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100053 ER PT B AU Sud, YC Mocko, DM AF Sud, YC Mocko, DM GP AMS AMS TI Land-atmosphere interactions: Successes, problems and prospects SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Climate Radiat Branch, Greenbelt, MD 20771 USA. RP Sud, YC (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Climate Radiat Branch, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 208 EP 209 PG 2 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100060 ER PT B AU Smith, EA Cooper, HJ Faysash, DA Tripoli, GJ AF Smith, EA Cooper, HJ Faysash, DA Tripoli, GJ GP AMS AMS TI Model validation of observed secondary circulation in FIFE-1989 IFC-5 dataset using coupled mesoscale-SVATS modeling system SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc ID BOUNDARY-LAYER CIRCULATIONS; SURFACE PROCESSES; FIFE-89 C1 NASA, GHCC, UAH Global Hydrol & Climate Ctr, Huntsville, AL 35806 USA. RP Smith, EA (reprint author), NASA, GHCC, UAH Global Hydrol & Climate Ctr, 977 Explorer Blvd, Huntsville, AL 35806 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 284 EP 284 PG 1 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100083 ER PT B AU Rickenbach, TM Cifelli, RC Halverson, JB Kucera, PA Thiele, OW AF Rickenbach, TM Cifelli, RC Halverson, JB Kucera, PA Thiele, OW GP AMS AMS TI Convective systems in contrasting regimes during TRMM-LBA in Rondonia, Brazil SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, TRMM Off, Greenbelt, MD 20771 USA. RP Rickenbach, TM (reprint author), NASA, Goddard Space Flight Ctr, TRMM Off, Code 910-1, Greenbelt, MD 20771 USA. NR 4 TC 1 Z9 1 U1 0 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 329 EP 332 PG 4 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100097 ER PT B AU Atlas, D Ulbricht, CW AF Atlas, D Ulbricht, CW GP AMS AMS TI An observationally based conceptual model of warm oceanic convective rain in the tropics SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Atlas, D (reprint author), NASA, Goddard Space Flight Ctr, Code 910 2, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 349 EP 350 PG 2 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100104 ER PT B AU Shepherd, JM AF Shepherd, JM GP AMS AMS TI Rainfall morphology in semi-tropical convergence zones SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Shepherd, JM (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 355 EP 358 PG 4 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100106 ER PT B AU Prabhakara, C Iacovazzi, R AF Prabhakara, C Iacovazzi, R GP AMS AMS TI Improved algorithm to estimate convective and stratiform rain from TRMM microwave radiometer data SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc ID PRECIPITATION AB The rain rates associated with Mesoscale Convective Systems (MCSs) deduced from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) follow the well known log-normal type frequency distribution characteristic of conventional radars and rain gauges. On the other hand, the current microwave radiometer rain retrieval algorithms cannot give good representations of convective and stratiform precipitation. Thus they capture poorly this log-normal character. In particular, this is noticed clearly over land areas. The objective of the present study is to improve TRMM Microwave Imager (TMI) retrievals of convective and stratiform rain to a level comparable to the PR. For this purpose, we have developed a TMI rain retrieval algorithm that depends primarily on the 85 GHz brightness temperatures (T(b)s) and their spatial distribution (Prabhakara et al., 1999b). We emphasize the 85 GHz channel because of its fine footprint size (similar to 5.5 km) and strong extinction property. The other spectral channels, because they are poorer in these respects, are given less importance. The brightness temperatures and spatial distribution information in the 85 GHz allows us to detect thunderstorms, or cumulonimbus clouds (Cbs), that are in different stages of development, as well as stratiform rain outside of these Cbs. Utilizing our retrieval technique, we have produced maps of convective and stratiform rain for several MCS events over land and ocean that agree well with those given by the PR. On average, the convective and stratiform rain rates given by our technique have an accuracy of about 15 % with respect to those given by the PR. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Prabhakara, C (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 359 EP 362 PG 4 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100107 ER PT B AU Huffman, GJ Adler, RF Bolvin, DT AF Huffman, GJ Adler, RF Bolvin, DT GP AMS AMS TI Incorporating TRMM and other high-quality estimates into the One-Degree Daily (1DD) Global Precipitation Product SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc ID DATASET C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Huffman, GJ (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 373 EP 374 PG 2 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100111 ER PT B AU Wang, JX Fisher, B Tokay, A Wang, JJ AF Wang, JX Fisher, B Tokay, A Wang, JJ GP AMS AMS TI An empirical study of TRMM-LBA rainfall SO 15TH CONFERENCE ON HYDROLOGY LA English DT Proceedings Paper CT 15th Conference on Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, TRMM Off, Greenbelt, MD 20771 USA. RP Wang, JX (reprint author), NASA, Goddard Space Flight Ctr, TRMM Off, Greenbelt, MD 20771 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 383 EP 384 PG 2 WC Meteorology & Atmospheric Sciences; Water Resources SC Meteorology & Atmospheric Sciences; Water Resources GA BS07R UT WOS:000168561100114 ER PT S AU Manduchi, R AF Manduchi, R BE Sanfeliu, A Villanueva, JJ Vanrell, M Alquezar, R Huang, T Serra, J TI A cluster grouping technique for texture segmentation SO 15TH INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION, VOL 3, PROCEEDINGS: IMAGE, SPEECH AND SIGNAL PROCESSING SE International Conference on Pattern Recognition LA English DT Proceedings Paper CT 15th International Conference on Pattern Recognition (ICPR-2000) CY SEP 03-07, 2000 CL BARCELONA, SPAIN SP Int Assoc Pattern Recognit, Assoc Pattern Recognit & Image Anal, Ctr Visio Comp, Univ Autonoma Barcelona, Univ Politecn Catalunya, Comissionat Universitats Recerca, Generalitat Catalunya Dept Presidencia, Minist Ciencia Tecnol, Fdn Catalana Recerca, HP Invent AB We propose an algorithm for texture segmentation based on a divide-and-conquer strategy of statistical modeling. Selected sets of Gaussian clusters, estimated via Expectation Maximization on the texture features, are grouped together to form composite texture classes. Our cluster grouping technique exploits the inherent local spatial correlation among posterior distributions of clusters belonging to the same texture class. Despite its simplicity, this algorithm can model even very complex distributions, typical of natural outdoor images. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM manduchi@jpl.nasa.gov NR 6 TC 2 Z9 3 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA SN 1051-4651 BN 0-7695-0750-6; 0-7695-0751-4 J9 INT C PATT RECOG PY 2000 BP 1060 EP 1063 PG 4 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BR56M UT WOS:000166814300252 ER PT S AU Olson, CF AF Olson, CF BE Sanfeliu, A Villanueva, JJ Vanrell, M Alquezar, R Crowley, J Shirai, Y TI Real-time ordnance recognition in color imagery SO 15TH INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION, VOL 4, PROCEEDINGS: APPLICATIONS, ROBOTICS SYSTEMS AND ARCHITECTURES SE INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION LA English DT Proceedings Paper CT 15th International Conference on Pattern Recognition (ICPR-2000) CY SEP 03-07, 2000 CL BARCELONA, SPAIN SP Int Assoc Pattern Recognit, Assoc Pattern Recognit & Image Anal, Ctr Visio Comp, Univ Autonoma Barcelona, Univ Politecn Catalunya, Comissionat Universitats Recerca, Generalitat Catalunya Dept Presidencia, Minist Ciencia Tecnol, Fdn Catalana Recerca, HP Invent AB Military test ranges containing unexploded ordnance due to five-fire testing and training exercises are a significant safety problem in many locations. Automated cleanup of such sites is a challenging goal. Towards this end, this paper describes algorithms to detect a type of ordnance in current usage using color imagery. The techniques are designed to run in real-time using off-the-shelf hardware for use on an unmanned ground vehicle. Our methodology is to quickly detect candidate locations using color and stereo information. Additional processing is Men applied to the candidate locations in order to eliminate false alarms. This technique has been tested on a set of imagery from a live-fire test range with outstanding results. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Olson, CF (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 125-209, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA SN 1051-4651 BN 0-7695-0751-4 J9 INT C PATT RECOG PY 2000 BP 685 EP 688 PG 4 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BR56Q UT WOS:000166815200158 ER PT B AU Cosgrove, BA Houser, PR Entin, JK AF Cosgrove, BA Houser, PR Entin, JK GP AMS AMS TI An interactive Web-based data analysis tool in support of the Land Data Assimilation Scheme (LDAS) project SO 16TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY AND HYDROLOGY LA English DT Proceedings Paper CT 16th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Cosgrove, BA (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 974, Greenbelt, MD 20771 USA. RI Houser, Paul/J-9515-2013 OI Houser, Paul/0000-0002-2991-0441 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 336 EP 339 PG 4 WC Computer Science, Interdisciplinary Applications; Meteorology & Atmospheric Sciences; Oceanography; Remote Sensing SC Computer Science; Meteorology & Atmospheric Sciences; Oceanography; Remote Sensing GA BS03Y UT WOS:000168410800102 ER PT B AU Oram, TD AF Oram, TD GP AMS AMS TI Creating first guess forecast products at NASA Johnson Space Center: Applying LAPS and AWIPS forecast preparation system algorithms in McIDAS SO 16TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY AND HYDROLOGY LA English DT Proceedings Paper CT 16th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, Lyndon B Johnson Space Ctr, Spaceflight Meteorol Grp, Houston, TX 77581 USA. RP Oram, TD (reprint author), NASA, Lyndon B Johnson Space Ctr, Spaceflight Meteorol Grp, ZS8, Houston, TX 77581 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 355 EP 356 PG 2 WC Computer Science, Interdisciplinary Applications; Meteorology & Atmospheric Sciences; Oceanography; Remote Sensing SC Computer Science; Meteorology & Atmospheric Sciences; Oceanography; Remote Sensing GA BS03Y UT WOS:000168410800107 ER PT B AU Bellue, DG Donohue, C AF Bellue, DG Donohue, C GP AMS AMS TI Upper wind forecasts for NASA's X-38 flight test operations SO 16TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY AND HYDROLOGY LA English DT Proceedings Paper CT 16th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology CY JAN 09-14, 2000 CL LONG BEACH, CA SP Amer Meteorol Soc C1 NASA, Lyndon B Johnson Space Ctr, Spaceflight Meteorol Grp ZS8, Houston, TX 77058 USA. RP Bellue, DG (reprint author), NASA, Lyndon B Johnson Space Ctr, Spaceflight Meteorol Grp ZS8, Houston, TX 77058 USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 369 EP 372 PG 4 WC Computer Science, Interdisciplinary Applications; Meteorology & Atmospheric Sciences; Oceanography; Remote Sensing SC Computer Science; Meteorology & Atmospheric Sciences; Oceanography; Remote Sensing GA BS03Y UT WOS:000168410800112 ER PT B AU Huang, J Zawadzki, M AF Huang, J Zawadzki, M BE Yaqiu, J TI Antennas integrated with solar arrays for space vehicle applications SO 2000 5TH INTERNATIONAL SYMPOSIUM ON ANTENNAS, PROPAGATION AND EM THEORY PROCEEDINGS LA English DT Proceedings Paper CT 5th International Symposium on Antennas, Propagation and EM Theory (ISAPE 2000) CY AUG 15-18, 2000 CL BEIJING, PEOPLES R CHINA SP Chinese Inst Electr, IEEE Antennas Propagat Soc, IEEE Geosci & Remote Sensing Soc, Inst Electr, Informat & Commun Engineers, Fudan Univ C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Huang, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6377-9 PY 2000 BP 86 EP 89 DI 10.1109/ISAPE.2000.894730 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BR27A UT WOS:000165985500023 ER PT B AU Wang, RT Dick, GJ AF Wang, RT Dick, GJ BE Hunter, J Johnson, L TI Stability tests of three Cryo-cooled Sapphire Oscillators SO 2000 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS DIGEST LA English DT Proceedings Paper CT Conference on Precision Electromagnetic Measurements (CPEM 2000) CY MAY 14-19, 2000 CL SYDNEY, AUSTRALIA SP Int Bur Weights & Measures, IEEE Instrumentat & Measurement Soc, Natl Inst Stand & Technol, Natl Res Council Canada, Union Radio Sci Int, CSIRO, Natl Measurement Lab, Natl Facil, Ind Sci Resources, Ind Res Ltd, Nat Assoc Testing Authorities, Stand Australia, Natl Stand Commiss, Joint Accreditat Syst Australia & New Zealand, Korea Res Inst Stand & Sci, Ctr Measurement Stand, ITRI, Fluke Corp, Int Union Pure & Appl Phys, Natl Conf Stand Labs, Oxford Instruments, Prema Prazisionselektron, Metrol Soc Australia, Texas Instruments, TransGrid AB We present frequency stability and phase noise results of three Cryo-cooled Sapphire Oscillators. Technical designs include cryo-cooler integration, compensated sapphire/ruby combination, and new receiver with Pound frequency lock circuit. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wang, RT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 1 Z9 1 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5745-0 PY 2000 BP 190 EP 191 DI 10.1109/CPEM.2000.850940 PG 2 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA BQ82P UT WOS:000089712400098 ER PT S AU Farr, TG AF Farr, TG GP IEEE IEEE TI The shuttle radar topography mission SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Meeting Abstract CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc C1 CALTECH, Jet Prop Lab, Pasadena, CA USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 63 EP 63 PG 1 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300005 ER PT S AU Liang, RM Tan, HH AF Liang, RM Tan, HH GP IEEE IEEE TI On the error analysis of single-channel free-access collision resolution algorithms SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Future wireless ATM networks proposed for providing OC-3 and above data rates generally employ demand assigned multiple-access protocols over time division multiplexed channels. Collision resolution algorithm based random access protocols (RAP) are useful for implementing the connection request procedure for these protocols. In the wireless networking environment, it is important to determine the performance of these protocols in the presence of propagation channel errors. This paper considers the performance of a single channel Q-array free-access collision resolution algorithm based RAP in the presence of memoryless feedback channel errors. The maximum stable throughput or capacity is derived for an infinite population Poisson user population model. The average delay-throughput characteristic is also derived. Simulations were performed to validate the analytical resultes. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Liang, RM (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NR 20 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 129 EP 139 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300014 ER PT S AU Breidenthal, JC AF Breidenthal, JC GP IEEE IEEE TI The merits of multi-hop communication in deep space SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The physics of communication give an advantage to multi-hop systems, because the ratio of power received to power transmitted on a telecommunications link of length S increases by a factor of n(2) if the link is divided in to rr equal hops of length S/n. If terminal characteristics are unchanged, the cost of a multi-hop system is higher than for a single hop, but the efficiency-to-cost ratio is n times better. Multi-hop systems can be scaled easily, have capacity that scales proportional to the square of the investment, are robust, and can provide multiple orders-of-magnitude increase of capacity in deep space using presently available technology. This remains true when noise introduced on each segment is taken into account, if modem error-control coding techniques are applied. Candidate mission designs for a multi-hop approach are discussed for high-capacity Earth-Mars and interstellar communication systems. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Breidenthal, JC (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 2 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 211 EP 221 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300022 ER PT S AU Alena, R Yaprak, E Lamouri, S AF Alena, R Yaprak, E Lamouri, S GP IEEE IEEE TI Modeling a wireless network for International Space Station SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper describes the application of wireless local area network (LAN) simulation modeling methods to the hybrid LAN architecture designed for supporting crew-computing tools aboard the International Space Station (ISS). These crew-computing tools, such as wearable computers and portable advisory systems, will provide crew members with real-time vehicle and payload status information and access to digital technical and scientific libraries, significantly enhancing human capabilities in space. A wireless network, therefore, will provide wearable computers and remote instruments with the high performance computational power needed by next-generation "intelligent'' software applications. Wireless network performance in such simulated environments is characterized by the sustainable throughput of data under different traffic conditions. This data will be used to help plan the addition of more access points supporting new modules and more nodes for increased network capacity as the ISS grows. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Alena, R (reprint author), NASA, Ames Res Ctr, MS 269-4, Moffett Field, CA 94035 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 223 EP 228 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300023 ER PT S AU Gudim, MA Gawronski, W AF Gudim, MA Gawronski, W GP IEEE IEEE TI Low noise signal processing technique for monopulse pointing of DSN 34-meter diameter antennas SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper describes a 31.8-32.3 GHz (Ka-band) monopulse antenna pointing system designed to meet a pointing precision requirement of a mean-radial-error (MRE) less than 1.5 milli-degrees for a 34-meter diameter antenna with a 17 milli-degrees 3-dB beam-width, under windy conditions up to 15 mph. The high precision is required for the Ka-band radio science experiments requiring high stability in the detected signal power. While the concept of monopulse pointing is not new, its application here is novel in that it is a physically large system tracking very weak signals with extremely fine pointing requirement. This system is modeled and analyzed as an equivalent phase-locked loop in each axis, azimuth and elevation, and also simulated as a two-dimensional system, including the cross-correlation between the two axes. Analysis and simulations agree. It is concluded that when implemented, the technique will meet the stated pointing requirement down to a signal-to-noise power spectral density ratio of 17 dB-Hz. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gudim, MA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 317 EP 328 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300033 ER PT S AU Manduchi, R Dolinar, S Pollara, F Matache, A AF Manduchi, R Dolinar, S Pollara, F Matache, A GP IEEE IEEE TI Onboard science processing and buffer management for intelligent deep space communications SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE Aerospace Conference Proceedings LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB We present an integrated system for the intelligent progressive transmission of data for deep space communications. This work is motivated by the realization that much more information can be collected by imaging and remote sensing equipment than can be transmitted through downlink channels. Suitable onboard science processing allows us to introduce semantics to the data collected by the imagine and remote sensing equipment. The data stream is then prioritized according to its significance in the image, and the most significant segments of data are transmitted first by means of a prioritized buffer management strategy. We show that this system allows to optimally exploit the limited onboard resources (downlink data rate, buffer size) and therefore to maximize the science return of a mission. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM manduchi@telerobotics.jpl.nasa.gov; sam@shannon.jpl.nasa.gov; fabrizio@shannon.jpl.nasa.gov; matache@shannon.jpl.nasa.gov NR 10 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 329 EP 339 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300034 ER PT S AU Shcheglov, K Evans, C Gutierrez, R Tang, TK AF Shcheglov, K Evans, C Gutierrez, R Tang, TK GP IEEE IEEE TI Temperature dependent characteristics of the JPL silicon MEMS gyroscope SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Advances in aeronautics and space technology have created a need for miniaturized navigation instruments such as gyroscopes, a need which is currently being addressed by a number of micromachined designs. While micromachined devices have already proven their advantages being lightweight and low-power, the performance limitations of these devices have not been thoroughly investigated. In particular the effects of the temperature environment on the performance is of great interest since they can be a dominant source of error in micromachined devices. We have investigated the temperature-dependent drift and noise characteristics of a packaged silicon MEMS gyroscopes. Packaged devices were subjected to various temperatures environments between -60 and +60 degreesC, and their resonant frequencies, signal drifts and quadrature drifts were monitored. The results obtained from these tests point out the mechanisms of temperature-dependent and temperature-independent drift and suggest a scheme for temperature compensation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Shcheglov, K (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 2 TC 20 Z9 30 U1 0 U2 3 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 403 EP 411 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300040 ER PT S AU Graves, DR AF Graves, DR GP IEEE IEEE TI Application of COTS for early, low cost, avionics system testbed SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The use of flight hardware breadboards to construct an avionics subsystem testbed has been very successfully used on past Jet Propulsion Laboratory (JPL) projects. These testbeds provide valuable early integration experience with the flight hardware and software operating together. Commercial off the shelf (COTS) based test systems are integrated with the flight hardware breadboards to create an Avionics testbed platform. The breadboard system has typically consisted of custom-built hardware that was quite expensive and time consuming to build and maintain. With level or decreasing NASA budgets, and faster, better, cheaper project mentality, the flight hardware breadboard has become a target of Federal budget cuts. Since the custom breadboards are not financially feasible, but the need for an early development avionics testbed still apparent, the role of the COTS hardware was expanded to include flight avionics functions. As an added benefit, the COTS hardware can be used as the basis for the flight hardware design. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91350 USA. RP Graves, DR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91350 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 413 EP 420 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300041 ER PT S AU Pingree, P AF Pingree, P GP IEEE IEEE TI Payload interoperability testing for the Mars '01 landed mission SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Jet Propulsion Laboratory's Mars Surveyor Operations Project (MSOP) is sending its next pair of spacecraft, an orbiter and a lander, to Mars in 2001. Success of the Mars '01 lander's primary mission objectives relies heavily on the interaction of the various payloads. The Payload Interoperability Testbed (PIT) is being developed at JPL to serve as a key verification facility for the Mars '01 project. The PIT provides a facility for testing payload interoperability functionality and sequences as well as an environment to train personnel for landed surface operations. This paper will define and describe the rationale for the PIT, its architecture, and the current test plan that has been developed for the PIT activities in support of the Mars '01 landed mission. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Pingree, P (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 198-136, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 421 EP 430 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300042 ER PT S AU Tung, YW Aldiwan, WS AF Tung, YW Aldiwan, WS GP IEEE IEEE TI Automating test case generation for the new generation mission software system SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The significant expansion of autonomous control and information processing capabilities in the coming generation of mission software systems results in a qualitatively larger space of behaviors that needs to be "covered" during testing, not only at the system level but also at subsystem and unit levels. A major challenge in this area is to automatically generate a relatively small set of test cases that, collectively, guarantees a selected degree of coverage of the behavior space. This paper describes an algorithm for a parametric test case generation tool that applies a combinatorial design approach to the selection of candidate test cases. Evaluation of this algorithm on test parameters from the Deep Space One mission reveals a valuable reduction in the number of test cases, when compared to an earlier home-brewed generator. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tung, YW (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 29 Z9 29 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 431 EP 437 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300043 ER PT S AU Evans, CB Gutierrez, RC AF Evans, CB Gutierrez, RC GP IEEE IEEE TI GAT/DeLiTe: An autonomous system for complete micro-gyroscope characterization SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The advancement of the MEMS micro-gyroscope development effort [1,2] at the Jet Propulsion Laboratory has necessitated the production of autonomous test equipment. A cost effective and efficient method of performing qualification testing and lifetime characterization was developed in response. Implemented as a set of two independent progranls, the Gyroscope Automated Testbed (GAT) and the Device Lifetime Testbed (DeLiTe), provide short-term stability and response characterization and longterm stability analysis. The two programs were designed to automate the time consuming task of performance analysis. accommodate the simultaneous testing of multiple devices, and reduce the risk of operator induced errors. Both systems are implemented on standard Intel-based personal computers using off-the-shelf data acquisition hardware. Specialized hardware or dedicated systems an not required, which results in a low cost system solution. This paper discusses the design and implementation of the two programs. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Evans, CB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 302-306, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 439 EP 453 PG 15 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300044 ER PT S AU Peterson, CE Heinrichs, WM AF Peterson, CE Heinrichs, WM GP IEEE IEEE TI Engineering data re-use at JPL: Promise and perils SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 1 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB In last year's IEEE Aerospace Conference Proceedings, a new approach to sharing engineering data using a Jet Propulsion Laboratory (JPL) developed Product Attribute Database (PAD) was described [1]. Since its development the PAD has been used on several projects at JPL with mixed results. The lessons learned in its implementation have wider implications for engineering processes and the associated data that is produced and consumed during a project's life cycle. In addition to the normal resistance of personnel to adopt a new tool who's benefits are not yet quantified in practice, the need to spend substantial effort early on to establish and promulgate a common understanding of the data has impeded acceptance and use of the PAD. The limitations of the original user interface and the lack of existing project data (either in template or detailed form) has also played a role in delaying widespread user acceptance. Despite these drawbacks, the initial use of the PAD has highlighted misunderstandings regarding definition of engineering data and has led to numerous fruitful discussions among engineering disciplines. Even apparently intuitively obvious data such as the "total. flight system mass" or the spacecraft mechanical configuration coordinate system have required refinement to eliminate the natural ambiguity that engineers routinely accommodate, but that leads to confusion when automated modeling tools are the creators and consumers of the data. These discussions have led to increased insight into engineering processes, particularly those using the model based design approach that is now being implemented at JPL. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Peterson, CE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 483 EP 489 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98E UT WOS:000165245300047 ER PT S AU Ryan, RE Warzynski, RR AF Ryan, RE Warzynski, RR GP IEEE IEEE TI Deep space mission operations: Reality or vision? SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The deep space mission operations process has changed over the years, and our service is perceived to be overly expensive. But in fact, costs have dropped recently, mainly due to improved approaches to missions. Missions are experimental by nature, and science and engineering improvements have accommodated their increasing complexity. Operations has steadily evolved and kept pace. And the result is increased science return. This paper discusses the new reality-operations must view each mission fresh, taking nothing for granted. Operations continually reviews mission plans progress and anticipates problems, adjusting quickly so requirements are met on time. This paper looks at operations history, its present state, and advances new ideas so Eye in operations will better evolve and adapt, constantly increasing our efficiency to meet customers' ever more complex needs:. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ryan, RE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 151 EP 155 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400014 ER PT S AU Fox, JJ Glass, BJ AF Fox, JJ Glass, BJ GP IEEE IEEE TI Impact of Integrated Vehicle Health Management (IVHM) technologies on ground operations for reusable launch vehicles (RLVs) and spacecraft SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Incorporation of Integrated Vehicle Health Management (IVHM) technologies into launch vehicle and spacecraft designs offers the potential for significant savings in operations costs. IVHM has three basic objectives. First is more autonomous operation in flight and on the ground, which directly translates to reduced workload on the ground controller team through reduction of raw vehicle data into "health summary information." Next is reduced ground processing of reusable vehicles due to more performance of system health checks in flight rather than back on the ground as well as more automated ground servicing and checkout. Lastly is enhanced vehicle safety and reliability due to increased capability to monitor system health using modern sensing systems inside even the harsh environment of an engine combustion chamber as well as through prediction of pending failures. The "integrated" piece of IVHM is the total integration of flight and ground NHM elements. The three elements of flight IVHM are advanced light weight/low power sensors, extensive real-time data processing and analysis and distributed data acquisition architecture with high-density mass storage. The two elements of ground IVHM are evolved control room architectures with advanced applications and automated ground processing systems. The traditional model of a vehicle's instrumentation system consists of a distribution of sensors, signal conditioning devices and multiplexing devices, a complex and cumbersome network of wiring and a centralized processor/recorder. Characteristics of a modem, distributed IVHM instrumentation system include modern sensors such as ultrasonic flow, photonic and Micro Electromechanical Systems based sensors leading to strategically placed "Health Nodes" with extensive data processing by system health diagnostic algorithms which in turn interface via fiber optic communication with a "master" processor-recorder. These diagnostic algorithms rely on models of system structure and definitions of nominal behavior, in comparison with actual system behavior, to identify and isolate current and predicted future faults. The flight system then interfaces with automated ground support equipment for system servicing and trend analysis. A status of current flight experiments on Space Shuttle, Deep Space-1, X-33, X-34 and X-37 will be presented. C1 NASA, Kennedy Space Ctr, FL USA. RP Fox, JJ (reprint author), NASA, Kennedy Space Ctr, FL USA. NR 13 TC 1 Z9 1 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 179 EP 186 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400017 ER PT S AU Campbell, J Smith, TH AF Campbell, J Smith, TH GP IEEE IEEE TI Ground operations considerations for design of human missions to Mars SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A study was conducted to determine the initial launch site requirements necessary to support a human mission to Mars. The Design Reference Mission 3.0 (DRM 3.0)([1]) was used to provide a baseline mission architecture. In addition, two launch vehicle configurations were evaluated; a partially reusable launch vehicle and a completely reusable two stage to orbit concept. The study concluded that the current mission architecture requiring launches every 30 days can be optimized in order to realize significant cost reductions for facility infrastructure at the launch site. Launch site considerations and mission architecture changes were identified that will reduce the infrastructure costs associated with launch site processing as well as reduce and simplify ground checkout. C1 NASA, Kennedy Space Ctr, Explorat Off, Kennedy Space Ctr, FL 32899 USA. RP Campbell, J (reprint author), NASA, Kennedy Space Ctr, Explorat Off, Kennedy Space Ctr, FL 32899 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 199 EP 207 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400019 ER PT S AU Kuo, NR AF Kuo, NR GP IEEE IEEE TI Mars Network operations concept SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB NASA has initiated at the Jet Propulsion Laboratory the design of a Communications and Navigation Network at Mars. It will consist of a constellation of low-altitude orbiting satellites and one or more areostationary (of synchronous orbit around Mars) satellites, as shown in Figure 1. The key Mars Network operations concept is to provide standard services and pave a way for interoperability of future Mars Missions. If is envisioned that the Mars Network will provide four types of services: telemetry and command data relay, position determination I, time synchronization, and proximity link telecom performance data service. Both scheduled and demand access paradigms were considered as options for the user to access these services. The adoption of the Consultative Committee for Space Data System (CCSDS) Proximity Link (proximity-1) protocol ensures the interoperability at the data link layer: The CCSDS File Delivery Protocol (CFDP) ensures the interoperability at the message and file transfer layer. One important feature of the Mars Network operation is that the orbiting satellites of the Mars Network are indistinguishable from the user's point of view. A user's data transfer transaction started with one satellite cart be continued with another satellite. This "cloud" topology greatly simplifies the users operations. We also introduce the concept of file based operation. The file based operation for Mars Network promotes autonomous network operations and provides better data accountability. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kuo, NR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 0 Z9 0 U1 0 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 209 EP 216 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400020 ER PT S AU Roy, WE AF Roy, WE GP IEEE IEEE TI Logistics considerations for a Human Mission to Mars SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Throughout the history of mankind, humans have ventured beyond their home base and source of support, and explored the unknown. Columbus, Lewis & Clark, and Scott are just a few examples of those brave explorers who sought out new lands and the potential of new discoveries. These explorers often spent months, even years, actively expanding the bounds of their limitations and resources. They successfully investigated new regions while overcoming many challenging and harsh environments. Humans are again poised to venture beyond their home base of Earth. This venture will rival the journeys of the early explorers especially in terms of mission duration and isolation from sources of supply and assistance. This next journey may be to Mars (Figure 1). The NASA Human Mars Mission (HMM) presents a multitude of technological challenges that must be addressed in order to safely send and return a crew to Mars. Once the manned phase of the mission is committed to launch, orbital mechanics will drive the crew to be away from Earth for a minimum of two years. There will be no re-supply and only a limited mass and volume allotment for logistics materials. The crew will have limited resources and capabilities available to them to maintain and repair the flight vehicle and the surface systems. Logistics will be one of the mole significant challenges the program must investigate, research, and eventually overcome. The program must provide for the long-term logistics supportability of vehicle systems and associated hardware where supply from Earth is non-existence. The crew will be asked to perform tasks normally not required of "today's" astronauts. Much like the early explorers, the crew must be able to handle all situations autonomously. This logistics challenge can be met by developing robust, redundant systems and by incorporating creative logistics solutions into the flight vehicle and surface system designs early in the program. C1 NASA, John F Kennedy Space Ctr, Kennedy Space Ctr, FL 32899 USA. RP Roy, WE (reprint author), NASA, John F Kennedy Space Ctr, Mailstop LO-P2, Kennedy Space Ctr, FL 32899 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 227 EP 233 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400022 ER PT S AU Cheung, KM Makovsky, A Taylor, J AF Cheung, KM Makovsky, A Taylor, J GP IEEE IEEE TI Telecommunications analysis service for DS1 planning and operations SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB In the "faster, better, cheaper" era, the Jet Propulsion Laboratory (JPL) continues to develop smaller and more frequent missions. The Deep Space Network (DSN) must track many spacecraft simultaneously. With ground tracking resources limited and with NASA moving into an era of full cost accounting, the need for an efficient and well-coordinated multi-mission telecommunications analysis service is apparent. This service is now provided as part of Telecommunications and Mission Operations Directorate (TMOD)'s Deep Space Mission System (DSMS). DS1 is the first mission to subscribe to TMOD's services. This paper describes the DS1 telecommunications link analysis service scenarios, including the DS1 safing incident on July 28, 1999, the day of Asteroid Braille flyby. The theme of this paper is to demonstrate that good people, efficient processes, and effective tools are key elements that enable 1) a wide range of cost-effective telecommunications analysis support, and 2) timely detection and anticipation of unforeseen situations.(1,2). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Cheung, KM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 161-260, Pasadena, CA 91109 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 249 EP 263 PG 15 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400025 ER PT S AU Acton, CH AF Acton, CH GP IEEE IEEE TI Planning and processing space science observations using NASA's SPICE system SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Navigation and Ancillary Information Facility (NAIF) team, acting under the directions of NASA's Office of Space Science, has built a data system-named SPICE-to assist scientists in planning and interpreting scientific observations from space-borne instruments. The principal objective of this data system is that it will provide geometric and other ancillary data used to plan space science missions and subsequently recover the full value of science instrument data returned from these missions, including correlation of individual instrument data sets with data from other instruments on the same or other spacecraft. SPICE is also used to support a host of mission engineering functions, such as telecommunications system analysis and operation of NASA's Deep Space Network antennas. This paper describes the SPICE system, including where and how it is used. It also touches on possibilities for further development and invites participation it this endeavor. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Acton, CH (reprint author), CALTECH, Jet Prop Lab, MS 301-125L,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 305 EP 310 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400031 ER PT S AU Fisher, F Knight, R Engelhardt, B Chien, S Alejandre, N AF Fisher, F Knight, R Engelhardt, B Chien, S Alejandre, N GP IEEE IEEE TI A planning approach to monitor and control for Deep Space communications SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB In recent years with the large increase in the number of space missions at NASA and JPL (Jet Propulsion Laboratory), the demand for deep space communications services to command and collect data from these missions has become more difficult to manage. In an attempt to increase the efficiency of operating deep space communications antennas, we are developing a prototype system to perform monitor, control, execution and recovery in order to automate the operations of the Deep Space Network (DSN) communication antenna stations. This paper describes the application of Artificial Intelligence planning techniques for antenna track plan generation and monitor and control for a NASA Deep Space Communications Station. The described system CLEaR (Closed Loop Execution and Recovery), will enable an antenna communications station to automatically respond to a set of tracking goals by correctly configuring the appropriate hardware and software and providing the requested communication services, while adapting itself to its dynamic environment. To perform this task, the Continuous Activity Scheduling, Planning, Execution and Replanning (CASPER) engine has been applied and extended to automatically produce antenna tracking plans that are tailored to support a set of input goals. Then during the execution of these track plans, CLEaR monitors the execution and adapts the track plan to the changing environment. In this paper, we will describe the antenna automation problem, the GASPER planning and scheduling system, how GASPER is used to generate antenna track plans and perform monitor and control during execution, and future work utilizing dynamic planning technology. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fisher, F (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 126-347, Pasadena, CA 91109 USA. NR 17 TC 1 Z9 1 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 311 EP 320 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400032 ER PT S AU Hill, MH AF Hill, MH GP IEEE IEEE TI Spacecraft analysis, MSAS - A multi-mission solution SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper describes the design of the JPL institutional Multi- Mission Spacecraft Analysis System (MSAS) its initial adaptation to the Cassini mission and adaptation strategies for smaller missions. Also discussed is the relationship of MSAS to the Flight Engineering Service paradigm proposed for support of future missions Fundamental to the MSAS design is the concept of a spacecraft state and the ability to define, track and manipulate spacecraft state information with a variety of analysis tools. The processing of this state information in a consistent manner from application to application is central to automating the spacecraft analysis tasks. A basic element of the MSAS design is an environmental core, which provides analysis capabilities, required by every mission and many operational elements of a flight team. The MSAS core design directly supports, in a seamless manner, the development of mission specific applications that reflect unique subsystem analysis requirements. The paper concludes with a discussion of the adaptation strategies of MSAS to smaller missions and describes the role of MSAS in the Flight Engineering Services paradigm being used at JPL to support multiple missions.(1,2) C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hill, MH (reprint author), CALTECH, Jet Prop Lab, Mail Stop 301-445,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 331 EP 339 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400034 ER PT S AU Lee, YH Specht, TE AF Lee, YH Specht, TE GP IEEE IEEE TI Remote access multi-mission processing and analysis ground environment (RAMPAGE) SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB At Jet Propulsion Laboratory (JPL), a goal of providing easy and simple data access to the mission engineering data using web-based standards to a wide variety of users is now possible by the RAMPAGE development. Because RAMPAGE provides platform independence by utilizing a freely available web browser instead of a special purpose workstation, a myriad of users are able to participate in multiple missions from any location via a virtual workstation environment. The first stage of RAMPAGE prototype was envisioned and developed while supporting the Galileo project and then to be followed by Deep Space 1 DS1) and Cassini project. The plan is to deploy the production system of RAMPAGE to support Mars 01 orbiter, Lander and Rover project, which is to be launched around March and April 2001. Discussions are also ongoing to deploy RAMPAGE to the Space InfraRed Telescope Facility (SIRTF) project which is to be launched December 2001. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lee, YH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 353 EP 358 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400036 ER PT S AU Norris, JS Backes, PG AF Norris, JS Backes, PG GP IEEE IEEE TI WEDDS: The WITS Encrypted Data Delivery System SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB WEDDS, the WITS Encrypted Data Delivery System, is a framework for supporting distributed mission operations by automatically transferring sensitive mission data in a secure and efficient manner to and from remote mission participants over the Internet. WEDDS was originally developed as part of WITS, the Web Interface for Telescience, and was to be used in the 1998 Mars Polar Lander Mission to support distributed mission operations over the Internet for the first time in NASA history. WEDDS is written in Java, and is designed to provide secure distributed operations capabilities to any existing mission application with little modification, and in a manner that is nearly transparent to the existing application and its users. WEDDS relies on the NASA Public Key Infrastructure (PKI) to verify the identity of remote users. Remote users must apply in person at a NASA security office or another trusted security authority in order to receive a digital certificate. All connections are made using the Secure Sockets Layer (SSL) protocol in conjunction with the user's certificate, and all transmissions are protected against eavesdropping through encryption with the Triple-DES-EDE3 algorithm. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Norris, JS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 198-221, Pasadena, CA 91109 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 359 EP 366 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400037 ER PT S AU Backes, PG Tso, KS Norris, JS Tharp, GK Slostad, JT Bonitz, RG AF Backes, PG Tso, KS Norris, JS Tharp, GK Slostad, JT Bonitz, RG GP IEEE IEEE TI Mars Polar Lander mission distributed operations SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE Aerospace Conference Proceedings LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID WEB AB The Mars Polar Lander (MPL) mission was the first planetary mission to use Internet-based distributed ground operations where scientists and engineers collaborate in daily mission operations from multiple geographically distributed locations via the Internet. This paper describes the operations system, the Web Interface for Telescience (WITS), which was used by the MPL mission for Internet-based operations. The MPL mission was a lander which landed near the south pole of Mars on December 3, 1999, although communication with the lander was never achieved. WITS was used for generating command sequences for the lander's robotic arm and robotic arm camera, and as a secondary tool for sequence generation for the stereo camera on the lander WITS was also used as a public outreach tool. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 0 Z9 0 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 367 EP 375 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400038 ER PT S AU Sherwood, R Schlutsmeyer, A Sue, M Wyatt, EJ AF Sherwood, R Schlutsmeyer, A Sue, M Wyatt, EJ GP IEEE IEEE TI Lessons from implementation of Beacon spacecraft operations on Deep Space One SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A new approach to mission operations has been flight validated on NASA's Deep Space One (DS1) mission that launched in October 1998. The beacon monitor operations technology is aimed at decreasing the total volume of downlinked engineering telemetry by reducing the frequency of downlink and the Volume of data received per pass. Cost savings are achieved by reducing the amount of routine telemetry processing and analysis performed by ground staff. With beacon monitoring, the spacecraft will assess its own health and will transmit one of four subcarrier frequency tones to inform the ground how urgent it is to track the spacecraft for telemetry. If all conditions are nominal, the tone provides periodic assurance to ground personnel that the mission is proceeding as planned without having to receive and analyze downlinked telemetry. If there is a problem, the tone will indicate that tracking is required and the resulting telemetry will contain a concise summary of what has occurred since the last telemetry pass. The Beacon technology has been proven successful on DS1 through a series of tone tests and data summarization experiments. This collection of experiments was called the DSI Beacon Monitor Experiment or BMOX. Still there are important lessons learned from this experiment that can be applied to future spacecraft missions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sherwood, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 377 EP 387 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400039 ER PT S AU Levesque, M Louie, J Guerrero, AM AF Levesque, M Louie, J Guerrero, AM GP IEEE IEEE TI Test Execution Control Tool: Automating testing in spacecraft integration and test environments SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB In the era of faster, better, cheaper, JPL aims to develop and integrate an ever increasing number of spacecraft. One of the problems JPL faces is to quickly, efficiently and accurately test these spacecraft in a diverse set of environments from the breadboard, to environmental simulation and through launch preparation. The Test Execution Control Tool was developed using a Tool Command Language (Tcl) [1] based test script interpreter to aid engineers in automating test procedures. Using the TECT, a tester can make the diverse collections of ground software, ground support equipment and flight systems work together through automated scripts. By allowing the tester to access and coordinate all the components of the complex testing environment, you not only achieve broader test coverage, leading to higher product assurance, but you achieve more speed and efficiency, leading to lower costs and faster results. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Levesque, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 1 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 389 EP 395 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400040 ER PT S AU Tung, RH Tong, KK AF Tung, RH Tong, KK GP IEEE IEEE TI A multi-mission deep space telecommunications analysis tool: The Telecom Forecaster Predictor SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Telecom Forecaster Predictor (TFP) fulfills the need for a powerful, easily adaptable, multi-mission telecommunications analysis tool. The software is used in operations by five JPL missions, and adaptations exist for 13 missions. Built upon MATLAB(R)(1), the TFP combines both multimission and mission-specific models to predict performance. Basing new mission adaptations on existing ones while sharing common models reduces development time and the number of modeling errors. configurations are specified through a user-friendly Graphical User Interface (GUI), and navigation inputs are provided through standard JPL NAIF SPICE2 SPK trajectory and CK attitude files, which the TFP can read directly. Current work involves the development of a mission planning tool based on the TFP architecture. The objective is to create an evolvable telecommunications analysis tool to support missions from start to finish. The modular architecture of the TFP is a solid framework; upon which other multi-mission tools can be modeled. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tung, RH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 161-260, Pasadena, CA 91109 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 397 EP 402 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400041 ER PT S AU James, ML Dubon, LP AF James, ML Dubon, LP GP IEEE IEEE TI An autonomous diagnostic and prognostic monitoring system for NASA's Deep Space Network SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Our objective is to provide a framework of automated tools and techniques for reducing operational and maintenance costs in the NASA's Deep Space Network (DSN). The focus of our technology application is fault diagnostics and prognostics for ground systems during DSN tracking operations. The domain chosen to demonstrate our capability is the new DSN Full Spectrum Processing Array configuration located at the Goldstone Deep Space Communications Complex (GDSCC) which is monitored by the Jet Propulsion Laboratory (JPL). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP James, ML (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 4 Z9 4 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 403 EP 414 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400042 ER PT S AU Brooks, RN AF Brooks, RN GP IEEE IEEE TI A multi-mission operations strategy for sequencing and commanding SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Telecommunications and Mission Operations Directorate (TMOD) of the Jet Propulsion Laboratory is responsible for development, maintenance and operation of flight operations systems for several classes of science missions planned for the next several years. The Mission Services and Applications (MS&A) Office is responsible for a large group of operations tasks, most of which are oriented toward the uplink leg of flight operations. These include sequence design and command generation, flight engineering tasks such as spacecraft activity planning and performance analysis, mission planning, telecommunications link analysis and DSN resource scheduling and planning. In addition, MS&A is responsible for the software tools necessary for performing these functions. The mission classes mentioned in the preceding paragraph are of the following four types. Standard operations class missions are characterized by the similarity and simplicity of their operational strategies. Most of these types of missions involve routine activities by both a spacecraft and its ground support teams. Another class of missions are those which will use the developing Mission Data System, a flight and ground operations system which will permit greater operations flexibility by developing a unified flight and ground architecture. A third type of mission is observatories. Examples of this class of mission would include SIRTF and SIM and would be characterized by heavy use of early observation planning and rapid turnaround flight sequence generation. Finally, the fourth class of missions involve mobile vehicles and sample returns. Operations for this mission type are planned for use beginning in 2001 and are currently in early development. The various mission classes have operational requirements, which are in many ways similar but differ sufficiently from one another to warrant development of a different type of operations strategy for each. Each of these operations strategies uses a standard set of tools developed by TMOD. A sequencing operations organization under the auspices the MS&A is now being built that will be responsible for the sequencing and commanding aspects of flight operations for all missions that subscribe to its services, including personnel, computer hardware and software, procedures and interfaces. This paper will describe the various mission types projected through the year 2006. It will then describe how TMOD/MS&A is planning to accommodate these missions operationally by providing a multi-mission sequencing and commanding capability which will be accessible to both new and existing missions. Finally, the projected resource savings and increases in efficiency will be discussed. C1 Jet Prop Lab, Telecommun & Mission Operat Directorate, Pasadena, CA 91109 USA. RP Brooks, RN (reprint author), Jet Prop Lab, Telecommun & Mission Operat Directorate, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 453 EP 458 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400047 ER PT S AU Scott, CJ AF Scott, CJ GP IEEE IEEE TI Vector animation: Web-based software training on demand SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB At the Jet Propulsion Laboratory(1), Training developers are creating vector animations to instruct engineers in the operation of mission software. These movies simulate interface software operations, providing a safe learning environment for flight teams. The technology is available as a COTS (Commercial Off The Shelf) program called Flash, a Macromedia product. Flash movies are low cost, highly productive, easily modified and maintained, and deliverable via Intranet. Animations are excellent vehicles for delivering training across the Internet; they are easy to understand and enjoyable to use. Since training is available any time of the day or night, users adopt their own pace, digesting information at a rate suitable for their learning style. There is no delay between actions, the user chooses a path but can change direction or return instantly. Action-oriented Flash movies are very powerful, relatively small, quick to load, and offer tremendous potential for increased productivity. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Scott, CJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 473 EP 479 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400050 ER PT S AU Osman, JW Barker, JT Rohrer, RA AF Osman, JW Barker, JT Rohrer, RA GP IEEE IEEE TI Automating the operations of NASA's Deep Space Network 26-meter antennas SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A development effort has been embarked on with the goal of improving the automation of some key components of NASA's Deep Space Network. This automation is intended to allow the DSN to support more missions with smaller budgets and fewer people. The development of these automation capabilities required not only a new set of hardware and software components, but also a significant change to the operational concepts that have been used to drive the design of the DSN for the last 20 years. This change to the DSN's operational scenarios should have an impact on future developments for all components of the DSN. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Osman, JW (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 481 EP 492 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400051 ER PT S AU Bergman, R AF Bergman, R GP IEEE IEEE TI XML technology enables redesigned Deep Space Network operations SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB NASA's Deep Space Network (DSN) provides telecommunication support for NASA's space exploration missions. Successful support relies on a great deal of information about each mission from equipment type to trajectory and encounter times. In the past, with only a handful of missions to support, this information was collected manually and telecommunication services were agreed upon manually. In the future, with an order of magnitude more missions flying, the DSN must automate its processes. The barriers to automation in the DSN environment are many: heterogeneous computing environments, legacy systems, existing procedures, etc. We advocate the use of the Extensible Markup Language (XML) as an enabling technology in our quest to automate DSN operations. In our development we are leveraging XML technology to solve several information exchange problems. This paper discusses three applications of XML to DSN automation: (I) the service request process, (2) legacy application integration, and (3) a DSN portal. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. RP Bergman, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91009 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 493 EP 502 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400052 ER PT S AU Lou, M Fang, HF Hsia, LM AF Lou, M Fang, HF Hsia, LM GP IEEE IEEE TI A combined analytical and experimental study on space inflatable booms SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 2 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Development and infusion of break-through technologies is needed to enable better, faster and cheaper space missions to be flown in the future. One of these technologies, space inflatable structure, is currently receiving much attention. The use of space inflatable structures can potentially revolutionize the architecture and design of many large, lightweight space systems that must have extremely high packing efficiency at launch and be reliably deployed in space. Examples of these systems include sunshields, solar arrays, solar sails, telescopes, concentrators, and space radar antennae. To facilitate effective designs of these space inflatable systems, the behaviors of their fundamental, building-block structural elements, the inflatable booms, need to be thoroughly characterized and understood. This paper presents experimental and analytical study results on different types of space inflatable booms, including the self-rigidizable carpenter-tape-reinforced aluminum laminate booms. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lou, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 503 EP 511 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98F UT WOS:000165245400053 ER PT S AU Duren, RM Tubbs, EF AF Duren, RM Tubbs, EF GP IEEE IEEE TI A modified commercial surveying instrument for use as a spaceborne rangefinder SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB We present a summary of the process used to create a reliable, mission-critical sensor from Commercial Off The Shelf (COTS) technology for the Shuttle Radar Topography Mission (SRTM). Measuring the length of the SRTM interferometric baseline to an accuracy of 2mm (1.6 sigma) is a key requirement. An electro-optical rangefinder instrument was recognized as the best option but funds and time were severely constrained. Therefore, the basic approach was to evaluate (though a series of quick tests) a robust commercial surveying instrument, make the necessary modifications for operation in space, followed by a rigorous test program. The result was the delivery of six flight-qualified units with accuracies of 1mm and at a cost significantly lower than that available with traditional methods. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Duren, RM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 1 EP 13 PG 13 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500001 ER PT S AU Yu, JR Singh, UN Barnes, NP Barnes, JC Petros, M Phillips, MW AF Yu, JR Singh, UN Barnes, NP Barnes, JC Petros, M Phillips, MW GP IEEE IEEE TI An all solid-state 2-mu m laser system for space coherent wind lidar SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID TM-YLF LASER; DESIGN; ND AB We describe a 2-mum diode-pumped, room temperature Ho:Tm:YLF laser and end-pumped amplifier system. The Ho:Tm:YLF oscillator utilized a multiple folded resonator with eight mirrors. A Q-switched output energy of 109 mi pulse was obtained at 6 Hz. This new design makes the laser a smaller size, which can be used in space application. The effects of laser operating temperature, thermal focusing and resonator structure rigidity on the performance of the laser were also investigated. In order to increase the laser system energy and efficiency, an end-pumped Ho:Tm:YLF disk amplifier was designed. Preliminary results showed that the efficiency of this laser amplifier could be better than 3% during Q-switch operation, a factor of three increase over side-pumped amplifier configuration. The laser system performance and its potential use for remote sensing of wind are presented in this paper. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Yu, JR (reprint author), NASA, Langley Res Ctr, MS 474, Hampton, VA 23681 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 27 EP 33 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500003 ER PT S AU Hemmati, H AF Hemmati, H GP IEEE IEEE TI Status of free-space optical communications program at JPL SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID DESIGN AB Optical communications is a rapidly developing technology applicable to future NASA and commercial space missions that desire a communications terminal that provides a higher data rate with lower mass and power. An experimental transmitter that will downlink data at the rate of 2.5 Gbps from the International Space Station is being constructed now. Under its X2000 program, JPL plans to develop a deep space optical communications transceiver for micro-spacecrafts that would, in an early demonstration, support 10's of Kbps data-rate from the Mars range. NASA is currently building a 1-m R&D telescope laboratory at its Table Mountain Facility in southern California to answer key implementation questions of this technology. The telescope is designed with fast tracking capability and will act as a testbed for development of ground acquisition, tracking and communications strategies applicable to future operational stations. These and other programs currently under development are described below. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hemmati, H (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 2 Z9 4 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 101 EP 105 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500013 ER PT S AU Spinhirne, JD Scott, VS Lancaster, RS Manizade, K Palm, SP AF Spinhirne, JD Scott, VS Lancaster, RS Manizade, K Palm, SP GP IEEE IEEE TI Performance and results from a space borne, uncooled microbolometer array spectral radiometric imager SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Infrared Spectral Imaging Radiometer experiment was flown on a space shuttle mission as a shuttle hitchhiker experiment in August of 1997. The goals of the experiment were to test uncooled array detectors for infrared spectral imaging from space and for the first time retrieve brightness temperatures of cloud, land and sea along with direct laser measurements of cloud top height from a space platform. The instrument operates in 3 narrow and one broad spectral band, all between 7 and 13 microns in either stare or time-delay and integration mode. The nominal spatial resolution was 1/4 kilometer. Using onboard calibrations along with periodic views of deep space, radiometric calibration of imagery was carried out and performance analyzed. The noise equivalent temperature difference and absolute accuracy reported here varied with operating mode, spectral band and scene temperature but were within requirements. This paper provides a description of the instrument, its operating modes, the method of brightness temperature retrieval, the method of spectral registration and results from the flight. C1 NASA, Goddard Space Flight Ctr 912, Greenbelt, MD 20771 USA. RP Spinhirne, JD (reprint author), NASA, Goddard Space Flight Ctr 912, Greenbelt, MD 20771 USA. RI Scott, Vibart/B-5086-2013 NR 6 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 125 EP 134 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500016 ER PT S AU Bruce, CF Bajaj, J Lee, D Pepper, TA Chu, G McLevige, WV Edwall, DD McGregor, LA Weissbard, W Hildebrandt, G Blackwell, JD Bhargava, S Gil, V Cooper, DE Spariosu, K Arias, JM Tennant, WE Vural, K Shin, L AF Bruce, CF Bajaj, J Lee, D Pepper, TA Chu, G McLevige, WV Edwall, DD McGregor, LA Weissbard, W Hildebrandt, G Blackwell, JD Bhargava, S Gil, V Cooper, DE Spariosu, K Arias, JM Tennant, WE Vural, K Shin, L GP IEEE IEEE TI Infrared detector assemblies for the Tropospheric Emission Spectrometer SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper provides an overview of the Tropospheric Emission Spectrometer (TES) and its mission, as a part of NASA's Earth Observing System (EOS). It will present, in detail, the design, fabrication and performance of the Infrared Focal Plane Assembly (IRFPA) used in this instrument. There are four IRFPAs, each covering one of four infrared spectral bands (3.3-5.3, 5.1-9.1, 8.3-12.2 and 11.1-15.4 mum). Each IRFPA consists of a 16-element detector array, a detector package, and a differential J-FET buffered transimpedance amplifier for each element with a flex-print cable that connects the cold detector package to the warm amplifier board. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bruce, CF (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 193 EP 205 PG 13 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500022 ER PT S AU Kahn, P AF Kahn, P GP IEEE IEEE TI Space Interferometry Mission: A systems perspective SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB In 2006, NASA's Origins Program will launch the Space Interferometry Mission (SIM), a 10 meter baseline optical interferometery instrument, into an earth trailing orbit. This instrument will be comprised of three colinear optical interferometers whose prime mission objective is to perform astrometric measurements of unparalleled accuracy. NASA has assembled an integrated Jet Propulsion Laboratory (JPL) / Industry team to formulate a reference design to meet the SIM Science objectives. Unique technical challenges have proved to be a formidable task in numerous aspects of the system definition, from component development to system-level integration and test. Parallel activities to develop and test the necessary enabling technologies for SLM are coupled with the ongoing Flight design. The SIM Project has taken a multi faceted approach to dealing with its numerous technical challenges. Key working groups are addressing specific, integrated areas such as thermal design, dynamics and control, and operations. In addition, detailed integrated models of optical systems, structural dynamics and thermal control systems are being implemented in a large integrated modeling effort in order to validate the system level performance requirements. The implementation of enabling technologies from picometer and nanometer technology testbed programs are crucial to developing a detailed design and mitigating or retiring risk early in the Project development cycle. This paper describes the current SIM Reference System Design, the key required technologies, the requirements development process and the approach to an integrated systems development. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kahn, P (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 207 EP 218 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500023 ER PT S AU Aaron, KM Stubbs, DM Kroening, K AF Aaron, KM Stubbs, DM Kroening, K GP IEEE IEEE TI Space interferometry mission instrument mechanical layout SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Space Interferometry Mission, planned for launch in 2006, will measure the positions of celestial objects to an unprecedented accuracy of 4x10(-6) are sec (about 1 billionth of a degree). In order to achieve this accuracy, which represents an improvement of almost two orders of magnitude over previous astrometric measurements, a ten-meter baseline interferometer will be flown in space. Starlight is collected by 33 cm diameter telescopes and combined to form fringes on detectors. To achieve the stated accuracy, the position of these fringes must be measured to a fraction of a wavelength of visible light. Passive vibration isolation and several layers of active control are used to stabilize the starlight wavefronts at sub-nanometer levels. Tight thermal control is coupled with very low CTE materials. Certain parts of the instrument need to be stabilized so that they move more slowly than the speed at which a baby grows. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Aaron, KM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 3 Z9 3 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 219 EP 230 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500024 ER PT S AU Kim, Y van Zyl, J AF Kim, Y van Zyl, J GP IEEE IEEE TI Overview of polarimetric interferometry SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID RADAR AB SAR (Synthetic Aperture Radar) interferometry has enabled two important science applications: surface change detection and topographic mapping. SAR interferometry is sensitive to the location of the imaged area and the scattering geometry. SAR polarimetry makes use of the polarization dependent scattering response of each pixel within the imaged area. The polarimetric response is highly sensitive to the scattering mechanism of a pixel. S. R. Cloude and K. P. Papathanassiou first published the formulation of polarimetric interferometry that combines both SAR interferometry and SAR polarimetry. The main purpose of using polarimetric interferometry is to extract scattering medium information that may be difficult to obtain from scalar interferometry. Even though the formulation and initial demonstrations appear to be very promising, potential applications of polarimeuic interferometry can only be verified by comparing polarimetric interferometry signatures with ground truth data. In this talk, we present the theory and implementation of SAR polarimetric interferometry. Especially, we review SAR polarimetry, SAR interferometry, and SAR polarimetric interferometry in a unified manner. In addition, a new calibration technique suitable for polarimetric interferometry is suggested in this paper. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kim, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 231 EP 236 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500025 ER PT S AU Pham, TT Jongeling, AP Rogstad, DH AF Pham, TT Jongeling, AP Rogstad, DH GP IEEE IEEE TI Enhancing telemetry and navigation performance with full spectrum arraying SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 3 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB At the start of the new millennium, a new arraying capability will be introduced into the NASA Deep Space Network (DSN). This is a second-generation system employing the fall spectrum combining technique first deployed to support the Galileo mission in 1996. The new arraying capability offers multi-mission support with real-time combining at higher data rates. In addition, for the first time in DSN history, it is also possible to array ranging signals to enhance navigation performance. With the enhanced signal-to-noise ratio (SNR) obtained from an effectively larger aperture, arraying enables support for missions whose signal level falls below the tracking threshold of a single antenna. Alternatively, it can also be used of increase the data return over that possible with a single antenna. In the extreme, the array deployment of four 34-meter antennas at Goldstone can substitute for the 70-meter antenna, the largest one in the network. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Pham, TT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 491 EP 498 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98G UT WOS:000165245500050 ER PT S AU Mason, LS Oleson, SR AF Mason, LS Oleson, SR GP IEEE IEEE TI Spacecraft impacts with advanced power and electric propulsion SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A study was performed to assess the benefits of advanced power and electric propulsion systems for various space missions. Advanced power technologies that were considered included multi-band gap and thin-film solar arrays, lithium batteries, and flywheels. Electric propulsion options included Hall effect thrusters and Ion thrusters. Several mission case studies were selected as representative of future applications for advanced power and propulsion systems. These included a low altitude Earth science satellite, a LEO communications constellation, a GEO military surveillance satellite, and a Mercury planetary mission. The study process entailed identification of overall mission performance using state-of-the-art power and propulsion technology, enhancements made possible with either power or electric propulsion advances individually, and the collective benefits realized when advanced power and electric propulsion are combined. Impacts to the overall spacecraft included increased payload, longer operational life, expanded operations and launch vehicle class step-downs. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Mason, LS (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 12 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 29 EP 38 PG 4 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700005 ER PT S AU Schreiber, JG AF Schreiber, JG GP IEEE IEEE TI Assessment of the stirling power option for space science applications SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Free-piston Stirling technology efforts in the past typically were intended to address power needs in the multi-kilowatt range. The Stirling power option was attractive primarily because of the high conversion efficiency and potential for long life. In recent years, several technology efforts have focused on the free-piston Stirling power convertor for space power applications, however the more recent efforts are intended to provide power at levels far below one kilowatt. Through a variety of projects funded by both NASA and DOE, the free-piston Stirling convertor technology has successfully demonstrated high efficiency and long life. Other areas of concern, such as control of multi-convertor systems, and vibration reduction have also been addressed. Efforts are being initiated to address issues such as electro-magnetic interference (EMT), radiation tolerance of organic materials, and the ability to operate through launch loads and survive with integrity. The status of the technology in these areas will be briefly discussed in this paper. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Schreiber, JG (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 39 EP 45 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700006 ER PT S AU Marrese, CM AF Marrese, CM GP IEEE IEEE TI A review of field emission cathode technologies for electric propulsion systems and instruments SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Cold Field Emission (FE) cathodes are being considered as the electron sources for propellant ionization and ion beam neutralization in electric propulsion systems. Compatible field emission cathodes will enable the development of microscale electric propulsion systems. The hostile environments of propulsion systems are very demanding on the cathode performance. Advanced cold FE cathode technologies are reviewed in this article. Field Emission Array (FEA) cathode materials and configurations were optimized using theoretical and experimental results to meet the demands of electric propulsion applications. It was determined that the FE cathode configurations and materials which are required for electric propulsion systems have not yet been fabricated. It is recommended that Mo FEA cathodes are fabricated with VECTL architectures and CLAIR structures and coated with carbide or carbon films to achieve performance and lifetime compatible with microscale electric propulsion systems. Instrument systems are much less demanding on the cathode performance; therefore the advantages of the recommended cathode configuration will also be realized for instrument systems. C1 Jet Prop Lab, Pasadena, CA 91101 USA. RP Marrese, CM (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91101 USA. NR 43 TC 6 Z9 6 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 85 EP 97 DI 10.1109/AERO.2000.878369 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700012 ER PT S AU Anderson, JR Goodfellow, KD Polk, JE Rawlin, VK Sovey, JS AF Anderson, JR Goodfellow, KD Polk, JE Rawlin, VK Sovey, JS GP IEEE IEEE TI Performance characteristics of the NSTAR ion thruster during an on-going long duration ground test SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A long-duration test of the Deep Space 1 (DS1) spare flight thruster (FT2) is presently being conducted. To date, the thruster has accumulated over 6700 hours of operation. Performance data-such as thrust, specific impulse and efficiency-over the fall 0.5 to 2.3 kW throttling range are presented. Comparison of FT2 with the performance of the engineering model thruster 2 (EMT2) during an 8.2 khr test shows a transient, lasting for about 3000 hours, during which the discharge chamber efficiency decreases for both thrusters. After the initial transient, the performance of both thrusters at full power is comparable with the exception of the electron backstreaming limit, which is 6 V lower for FT2. Degradation of electrical isolation for neutralizer and for discharge cathode components has occurred during FT2 testing; although this has made starting the thruster slightly more difficult, it is not expected to cause thruster failure. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Anderson, JR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 16 TC 1 Z9 1 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 99 EP 121 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700013 ER PT S AU Polk, JE Kakuda, RY Anderson, JR Brophy, JR Rawlin, VK Sovey, J Hamley, J AF Polk, JE Kakuda, RY Anderson, JR Brophy, JR Rawlin, VK Sovey, J Hamley, J GP IEEE IEEE TI In-flight performance of the NSTAR ion propulsion system on the Deep Space One Mission SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Deep Space 1 is the first interplanetary spacecraft to use an ion propulsion system for the primary delta-v maneuvers. The purpose of the mission is to validate a number of technologies, including ion propulsion and a high degree of spacecraft, autonomy, on a flyby of an asteroid and two comets. The ion propulsion system has operated for a total of 3500 hours at engine power levels ranging from 0.48 to 1.94 kW and has completed the encounter with the asteroid 1992KD and the first set of deterministic burns required for a 2001 encounter with comet Wilson-Harrington. The system has worked extremely well after an initial grid short was cleared after launch. Operation during this primary mission phase has demonstrated all ion propulsion system and autonomous navigation functions. All propulsion system operating parameters are very close to the expected values with the exception of the thrust at higher power levels, which is about 2 percent lower than that calculated from the electrical parameters. This paper provides an overview of the system and presents the first flight validation data on an ion propulsion system in interplanetary space. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Polk, JE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 17 TC 0 Z9 0 U1 1 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 123 EP 147 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700014 ER PT S AU Mueller, J Chakraborty, I Vargo, S Marrese, C White, V Bame, D Reinicke, R Holzinger, J AF Mueller, J Chakraborty, I Vargo, S Marrese, C White, V Bame, D Reinicke, R Holzinger, J GP IEEE IEEE TI Towards micropropulsion systems on-a-chip: Initial results of component feasibility studies SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Recent advances in the development of several micropropulsion components performed at JPL for microspacecraft applications are reported upon. These include a vaporizing liquid micro-thruster, a micro ion engine, a micro-isolation valve, a micro-piezo valve, and a micro solenoid valve. The latter is being developed in collaboration with Moog Space Products Division. These components are envisioned to be integrated with chip-based driver and power conditioning electronics into highly integrated, compactly configured micropropulsion modules, reducing overall system weight and size as well as cost and complexity of propulsion system integration. Proof-of-concept demonstration for several of the concepts was recently obtained. A vaporizing liquid thruster chip was able to demonstrate vaporization of water propellant at a power level of 2 W. A micro-isolation valve could be opened at an energy of 16 mi within 0.1 ms, and sustain burst pressures of up to 3,000 psig. C1 Jet Prop Lab, Pasadena, CA 91106 USA. RP Mueller, J (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91106 USA. NR 51 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 149 EP 168 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700015 ER PT S AU Hench, JJ Lurie, B Grogan, R Johnson, R AF Hench, JJ Lurie, B Grogan, R Johnson, R GP IEEE IEEE TI Implementation of nonlinear control laws for an optical delay line SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc DE nonlinear control; coarse-vernier control; optical delay line; interferometer AB This paper discusses the implementation of a globally stable nonlinear controller algorithm for the Realtime Interferometer Control System Testbed (RICST) brassboard optical delay line (ODL) developed for the Interferometry Technology Program at the Jet Propulsion Laboratory. The control methodology essentially employs loop shaping to implement linear control laws, while utilizing nonlinear elements as means of ameliorating the effects of actuator saturation in its coarse, main, and vernier stages. The linear controllers were implemented as high-order digital filters and were designed using Bode integral techniques to determine the loop shape. The nonlinear techniques encompass the areas of exact linearization, anti-windup control, nonlinear rate limiting, and modal control. Details of the design procedure are given as well as data from the actual mechanism. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hench, JJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 345 EP 357 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700033 ER PT S AU Lee, M Weidner, RJ Lu, WW AF Lee, M Weidner, RJ Lu, WW GP IEEE IEEE TI Mission lifecycle modeling and simulation SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Mission synthesis and simulation research at the Jet Propulsion Laboratory addresses mission model taxonomy, progressive lifecycle representation, model-based mission design, and simulation-in-the-loop design. The Virtual Mission (VM) project integrates the research activities and implements a virtual mission lifecycle to enable a globally optimal mission. The VM is composed of three interacting modeling and simulation layers: a mission model architecture layer, a mission system simulation layer, and a mission operation simulation layer. The three layers collectively simulate the development, integration, and operation phases of the mission cycle for comprehensive validation of mission design products. The VM was applied for the MICAS (Miniature Imaging Camera And Spectrometer) payload system of the Deep Space I mission (DS1) to validate the integrated system's performance to ensure the desired science return. The VM is being applied to design and to validate calibration scenarios and science observation scenarios for the extended science mission of the DSI project. C1 CALTECH, Jet Prop Lab, Pasadena, CA 90272 USA. RP Lee, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 90272 USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 379 EP 388 PG 4 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700037 ER PT S AU Turmon, M Granat, R AF Turmon, M Granat, R GP IEEE IEEE TI Algorithm-based fault tolerance for spaceborne computing: Basis and implementations SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB We describe and test the mathematical background for using checksum methods to validate results returned by a numerical subroutine operating in a fault- prone environment that causes unpredictable errors in data. We can treat subroutines whose results satisfy a necessary condition of a linear form; the checksum tests compliance with this necessary condition. These checksum schemes are called algorithm-based fault tolerance (ABFT). We discuss the theory and practice of setting numerical tolerances to separate errors caused by a fault from those inherent in finite-precision numerical calculations. Two series of tests are described. The first tests the general effectiveness of the linear ABFT schemes we propose, and the second verifies the correct behavior of our parallel implementation of them. We find that under simulated fault conditions, it is possible to choose a fault detection scheme that for average case matrices can detect 99% of faults with no false alarms, and that for a "worst-case" matrix; population can detect 80% of faults with no false alarms. C1 CALTECH, Jet Prop Lab, Machine Learning Syst Grp, Pasadena, CA 91109 USA. RP Turmon, M (reprint author), CALTECH, Jet Prop Lab, Machine Learning Syst Grp, M-S 126-347, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 411 EP 420 PG 4 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700040 ER PT S AU Penix, J Fischer, B Whittle, J Pour, G Van Baalen, J AF Penix, J Fischer, B Whittle, J Pour, G Van Baalen, J GP IEEE IEEE TI Automating component integration for Web-based data analysis SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID PROGRAM AB In this paper, we describe a component-based infrastructure for Web-based data analysis applications that reduces the need for custom integration programming. Our vision is that, to construct an application, scientists will give a specification of three kinds of components: the desired data source, a data analysis filter, and a visualization device. From this specification, our infrastructure will automatically generate the desired application. To support this vision, the infrastructure contains an intelligent component integration system (iCIS) that automates component retrieval, adaptation, and integration. Within iCIS, component knowledge is represented using formal mathematical specifications, to provide a common framework for reasoning about problem decomposition, component retrieval and adapter generation. Our current focus is on integration of data analysis filters with online data archives described using XML-based languages. We also discuss how iCIS is integrated with a 3-tier client/server application architecture to support in a heterogeneous and distributed computing environment. C1 NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 USA. RP Penix, J (reprint author), NASA, Ames Res Ctr, Computat Sci Div, M-S 269-2, Moffett Field, CA 94035 USA. NR 30 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 465 EP 473 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700045 ER PT S AU Larson, S Rengarajan, K AF Larson, S Rengarajan, K GP IEEE IEEE TI A framework-based approach to science software development SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Tropospheric Emission Spectrometer (TES) is a Fourier transform spectrometer slated for launch in December 2002. Its six-year mission to provide a 3-dimensional map of ozone and its precursors is part of NASA's Earth Observation System (EOS). TES is expected to produce approximately 8.4 TB of raw data and an additional 25 TB of processed data each year. The data are to be archived and distributed by NASA's EOS Data and Information System (EOSDIS). Processing this data requires the development of a large, robust software system capable of automated operations, sufficiently maintainable to support ongoing revision of the processing algorithms. The target platform for the TES science software provides a rich set of job control functions. However, the changeable nature of the underlying science algorithms mandates a high degree of maintainability in the science software. The long time period over which the software is developed and maintained suggests a framework-based approach to system development. We describe plans for the development of an application framework to support TES, including requirements, architecture, technical and management issues. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Larson, S (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 475 EP 490 PG 4 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700046 ER PT S AU Larson, S Morrison, B AF Larson, S Morrison, B GP IEEE IEEE TI Managing software requirements in the context of the scientific enterprise SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 4 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Developing production-quality software as part of a scientific research program presents unique challenges. Some of the techniques for managing requirements in this context which have evolved over the last three decades at the Jet Propulsion Laboratory are discussed. The software development effort in support of the Tropospheric Emission Spectrometer (TES) project is presented as an example of the application of these methods. In certain respects the methods discussed appear to deviate from commonly accepted practice. In an effort to explain the success of these methods, some novel information from the field of cognitive science is explored. We discuss our assumptions about the underlying model of scientific process. The tension between the dualistic view of the world assumed by scientists, and the nondualistic nature of our solutions to the problems of software development is also discussed. We conclude with a discussion of our experience relative to current research into social methods of requirements engineering. We find that scientists are a unique type of customer, with unique needs from the software development process itself, and not just the end product as many methodologies assume. A social-based approach to development has proven to be the most efficient means of mitigating the difficulties posed by language, educational and cultural barriers. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Larson, S (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 16 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 509 EP 522 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98H UT WOS:000165245700049 ER PT S AU Adams, JT Lux, JP AF Adams, JT Lux, JP GP IEEE IEEE TI Ground calibration of an orbiting spacecraft transmitter SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The SeaWinds Calibration Ground Station (CGS) is a novel Ku-band receiving station that supports the June 1999-launched JPL/NASA SeaWinds scatterometer radar which measures the near-surface wind speeds over 90% of the ice-free oceans. The CGS purpose is to measure very accurately the radar pulse timing, frequency and amplitude characteristics in order to monitor independently the radar and spacecraft platform performance over the course of the mission. These data are critical to maintaining or improving the quality of the end-data product. Results are presented here which show the ability to measure spacecraft pulse timing to microsecond detail, spacecraft attitude to better than 0.1 degrees, and output amplitude that will in future work allow estimation of the spacecraft on-orbit antenna pattern These efforts will improve registration of the scatterometer-derived wind map to the Earth's coordinate system and provide an independent assessment of the instrument quality over the life of the mission. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Adams, JT (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 37 EP 49 PG 13 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800004 ER PT S AU Huang, J Feria, A Lou, M AF Huang, J Feria, A Lou, M GP IEEE IEEE TI The development of inflatable array antennas SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID MICROSTRIP AB Three inflatable array antennas recently developed for spacecraft applications are a 3.3m x 1.0m L-band synthetic aperture radar (SAR) array, a 1.0m-diameter X-band telecom reflectarray, and a 3m-diameter Ka-band telecom reflectarray. All three antennas are similar in construction and each consists of an inflatable tubular frame that supports and tensions a multi-layer thin-membrane RF radiating surface with printed microstrip patches. The L-band SAR array achieved a bandwidth of 80 MHz, an aperture efficiency of 74%, and a total mass of 15 kg. The X-band reflectarray achieved an aperture efficiency of 37%, good radiation patterns, and a total mass of 1.2 kg (excluding inflation system). The 3m Ka-band reflectarray achieved a surface flatness of 0.1 mm RMS, good radiation patterns, and a total mass of 12.8 kg (excluding inflation system). These antennas demonstrated that inflatable arrays are feasible across the microwave and millimeterwave spectrums. Further development of these antennas are deemed necessary, in particular, in the area of qualifying the inflatable structures for space environment usage. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Huang, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 59 EP 65 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800006 ER PT S AU Manshadi, F AF Manshadi, F GP IEEE IEEE TI The new ultra low noise diplexed X-band microwave feed for NASA 70-m antennas SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper describes the configuration, detail design, and performance of a new ultra low noise diplexed X-band microwave feed system, called X/X diplexing feed, for the Deep Space Network (DSN) 70-m antennas. In this microwave feed, the uplink signal is combined with the downlink signal in a diplexing junction placed near the input of a wide-band feedhorn. This configuration allows the majority of the components in the downlink path to be placed in a cryogenically cooled container, resulting in a drastic reduction in the loss (noise temperature) of the feed. Combined with low noise High Electron Mobility Transistor (HEMT) amplifiers, this feed provides the lowest noise diplexed feed in the DSN. The total noise temperature of the 70-m antennas with this feed is estimated to be 16.1 Kelvin. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Manshadi, F (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 73 EP 76 PG 4 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800008 ER PT S AU Hussein, ZA Im, E AF Hussein, ZA Im, E GP IEEE IEEE TI Analysis of Cassegrain cloud profiling radar antenna with arbitrary projected apertures SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A millimeter wave Cassegrain dual-reflector radar antenna (similar to 94GHz) with super-quadric projected aperture boundaries concept, that includes sub-reflector blockage effect, is evaluated for the spaceborne radar measurement of the vertical cloud profile structure. In this paper, we show how the super-quadric aperture representation may be used for optimizing the antenna radiation performance. This facilitates to reduce the noise/clutter level received by the radar through the antenna. Its application is where the design specifications stipulate desired radiation characteristics (gain, sidelobe levels and beam widths) and maximum allowable antenna dimensions for a nadir-looking beam. Model results based on physical optics (PO) and uniform theory of diffraction, (UTD), for different projected apertures super-quadric boundaries show that the trends of the antenna patterns in the principal planes differ significantly from those in the +/-45 degrees planes. These unique characteristics along with the pronounced impact of the edge tapers on the first sidelobe level relative to the adjacent ones provide a basis to obtain an optimum antenna design for the instrument. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hussein, ZA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 101 EP 106 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800012 ER PT S AU Jamnejad, V Riley, AL Swindlehurst, RT AF Jamnejad, V Riley, AL Swindlehurst, RT GP IEEE IEEE TI Reflector antenna systems for the high altitude MMIC sounding radiometer (HAMSR) SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper describes the reflector antenna system for the High altitude MMIC sounding radiometer (HAMSR) on a remotely piloted aircraft. The goal of HAMSR project is to design, build, and demonstrate in the field, a miniaturized microwave atmospheric sounder implemented with Monolithic Microwave Integrated Circuit (MMIC) receiver modules and other solid state components. This passive microwave radiometer operating at millimeter wavelengths will make temperature soundings at oxygen emission lines at 53 and 118 GHz, and humidity sounding at water vapor emission line at 183 GHz. In this paper we will outline the design process and the analytic results for the three feed/reflector systems at the above three frequencies. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jamnejad, V (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 113 EP 117 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800014 ER PT S AU Njoku, E Wilson, W Yueh, S Freeland, R Helms, R Oxnevad, K Campbell, T Lawrence, W Rahmat-Samii, Y Feingold, H Didinsky, G Rauwolf, J AF Njoku, E Wilson, W Yueh, S Freeland, R Helms, R Oxnevad, K Campbell, T Lawrence, W Rahmat-Samii, Y Feingold, H Didinsky, G Rauwolf, J GP IEEE IEEE TI Large deployable-mesh antenna system for ocean salinity and soil moisture sensing SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A concept has been studied for remote sensing of sea surface salinity and soil moisture from space using a large deployable mesh antenna system. The antenna has a 6-m-diameter offset-fed parabolic reflector with multichannel feedhorns operating at L and S bands. The antenna boresight is offset from nadir and the entire system rotates about the nadir axis, providing a conical scan with high-precision measurements across a wide swath at a spatial resolution of about 40 km from a 600-km orbit altitude. The study includes evaluation of deployable mesh antennas and preferred antenna, spacecraft, and launch vehicle configurations. Designs for compact, lightweight feedhorns and radiometer/radar electronics are being developed and evaluated. Laboratory measurements of the emissivity of mesh samples under simulated orbital conditions are being made to evaluate the suitability of current mesh designs for high-precision radiometric applications. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Njoku, E (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 141 EP 150 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800017 ER PT S AU Im, E Durden, SL Sadowy, G Berkun, A Huang, J Lou, M Lopez, BC Rahmat-Samii, Y Rengarajan, S AF Im, E Durden, SL Sadowy, G Berkun, A Huang, J Lou, M Lopez, BC Rahmat-Samii, Y Rengarajan, S GP IEEE IEEE TI System concept for the next-generation spaceborne Precipitation Radars SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID RAIN-MAPPING RADAR AB The 13.8-GHz Precipitation Radar (PR) abroad the US/Japan Tropical Rainfall Measuring Mission (TRMM) satellite is the first rain profiling radar ever launched into space. A TRMM follow-on mission, called the Global Precipitation Mission (GPM), is currently planned to extend and to improve the TRMM acquired rainfall data set. One of the key components of the GPM science instrumentation is an advanced, dual-frequency rain mapping radar. In this paper, we present a system concept for this second-generation spaceborne precipitation radar (PR-2) for the GPM. The key PR-2 system consists of: (1) a 13.6/35 GHz dual frequency radar electronics that has Doppler and dual-polarization capabilities; (2) a large but Light weight, dual-frequency, wide-swath scanning, deployable antenna; (3) digital chirp generation and the corresponding on-board pulse compression scheme to allow a significant improvement on rain signal detection without using the traditional, high-peak-power transmitters and without sacrificing the range resolution; (4) an approach to adaptively scan the antenna so that more time can be spent to observe rain rather than clear air; and (5) the built-in flexibility on the radar parameters and timing control such that the same radar can be used by different future rain missions. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Im, E (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 0 Z9 0 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 151 EP 158 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800018 ER PT S AU Beahan, J Edmonds, L Ferraro, RD Johnston, A Katz, DS Some, RR AF Beahan, J Edmonds, L Ferraro, RD Johnston, A Katz, DS Some, RR GP IEEE IEEE TI Detailed radiation fault modeling of the Remote Exploration and Experimentation (REE) first generation testbed architecture SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The goal of the NASA HPCC Remote Exploration and Experimentation (REE) Project is to transfer commercial supercomputing technology into space. The project will use state of the art, low-power, nonradiation-hardened, Commercial Off-The-Shelf (COTS) hardware chips and COTS software to the maximum extent possible, and will rely on Software-Implemented Fault Tolerance (SIFT) to provide the required levels of availability and reliability. In this paper, we outline the methodology used to develop a detailed radiation fault model for the REE Testbed architecture. The model addresses the effects of energetic protons and heavy ions which cause Single Event Upset (SEU) and Single Event Multiple Upset (SEMU) events in digital logic devices and which are expected to be the primary fault generation mechanism. Unlike previous modeling efforts, this model will address fault rates and types in computer subsystems at a sufficiently fine level of granularity (i.e., the register level) that specific software and operational errors can be derived. We present the current state of the model, model verification activities and results to date, and plans for the future. Finally, we explain the methodology by which this model will be used to derive application-level error effects sets. These error effects sets will be used in conjunction with our Testbed fault injection capabilities and our applications' mission scenarios to replicate the predicted fault environment on our suite of onboard applications. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Beahan, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. OI Katz, Daniel S./0000-0001-5934-7525 NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 279 EP 281 PG 3 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800033 ER PT S AU Ghaffarian, R AF Ghaffarian, R GP IEEE IEEE TI Shock and thermal cycling synergism effects on reliability of CBGA assemblies SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Ball Grid Arrays (BGAs) are now packages of choice especially for higher I/O counts for commercial applications and are also being considered for use in military and aerospace. Thermal cycling characteristics of EGA assemblies have been widely reported including those by the JPL-led consortium. Thermal cycling represents the on-off environmental condition for most electronic products and therefore is a key factor that defines reliability. As a results, much data available for accelerated thermal cycle conditions, but very limited data is available on vibration and shock representative of aerospace applications. Test vehicles with daisy chain plastic and ceramic BGAs (CBGAs) ranging from 256 to 625 I/O count were subjected to random vibration/shock representative of a spacecraft launch environment. The effect of board rigidity on behavior was also investigated by adding strips to or bonding of board to an Aluminum plate. This paper compares accelerated thermal cycles-to-failure data under four temperature ranges before and after thermal random vibration for CBGAs with 361 and 625 I/Os. Stress and strain projections by finite element analysis are also presented. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ghaffarian, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 6 Z9 6 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 327 EP 333 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800039 ER PT S AU Carr, GA Wester, G Danielak, B Sauers, JD Hogue, D Holic, J AF Carr, GA Wester, G Danielak, B Sauers, JD Hogue, D Holic, J GP IEEE IEEE TI X2000 Power System Electronics development SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Deep Space System Technology Program (X2000) is managed by JPL for NASA. The program is designed to provide advanced flight and ground systems for the exploration of the outer planets. The X2000 Integrated First Delivery Project under DSST will provide flight avionics for the first set of mission customers, Europa Orbiter, Pluto/Kuiper Express and Solar Probe. These missions provide a challenge in terms of extreme environmental requirements. The key driving requirements are the one mega-rad total ionizing dose and the fifteen-year life. The X2000 Power System Electronics must reduce its power, mass and volume envelope by incorporating new technology developed by industry partners. The combination of Multi-chip module (MCM) packaging, rad-hard mixed signal application-specific integrated circuits (ASICs) and next-generation-power devices increases the packaging density of the Power System Electronics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Carr, GA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 341 EP 354 PG 14 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800041 ER PT S AU Button, RM Kascak, PE Lebron-Velilla, R AF Button, RM Kascak, PE Lebron-Velilla, R GP IEEE IEEE TI Digital control technologies for modular DC-DC converters SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Recent trends in aerospace Power Management and Distribution (PMAD) systems focus on using commercial off-the-shelf (COTS) components as standard building blocks. This move to more modular designs has been driven by a desire to reduce costs and development times, but is also due to the impressive power density and efficiency numbers achieved by today's commercial DC-DC converters. However, the PMAD designer quickly learns of the hidden "costs'' of using COTS converters. The most significant cost is the required addition of external input filters to meet strict electromagnetic interference (EMI) requirements for space systems. In fact; the high power density numbers achieved by the commercial manufacturers are greatly due to the lack of necessary input filters included in the COTS module. The NASA Glenn Research Center is currently pursuing a digital control technology that addresses this problem with modular DC-DC converters. This paper presents the digital control technologies that have been developed to greatly reduce the input filter requirements for paralleled, modular DC-DC converters. Initial test result show that the input filter's inductor size was reduced by 75%, and the capacitor size was reduced by 94% while maintaining the same power quality specifications. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Button, RM (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 355 EP 362 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800042 ER PT S AU Johnston, AH Guertin, SM AF Johnston, AH Guertin, SM GP IEEE IEEE TI The effects of space radiation on linear integrated circuits SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID OPTOCOUPLERS; TRANSIENTS; DAMAGE; ANALOG AB Permanent and transient effects are discussed that are induced in linear integrated circuits by space radiation. Recent developments include enhanced damage at low dose rate, increased damage from protons due to displacement effects, and transients in digital comparators that can cause circuit malfunctions. Methods of selecting and testing devices for space applications are discussed, along with examples of radiation effects in fielded space systems. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnston, AH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 17 TC 0 Z9 0 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 363 EP 369 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800043 ER PT S AU Strauss, KF Daud, T AF Strauss, KF Daud, T GP IEEE IEEE TI Overview of radiation tolerant unlimited write cycle non-volatile memory SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID END AB We describe X2000, a new concept in JPL's avionics development. Further, a need for non-volatile radiation hardened memory is brought forth. A 1 Mega-bit/in(2) memory density specification: 10 year lifetime, 1-MegaRad total ionizing radiation dose survivability, and > 10(13) write cycles is drawn for such NASA's missions as Europa Orbiter as the first delivery for X2000. We present an overview related with the Government development effort for three such new memory technologies. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Strauss, KF (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 399 EP 408 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800048 ER PT S AU Yuan, J Patel, JU Vandooren, A AF Yuan, J Patel, JU Vandooren, A GP IEEE IEEE TI Performance evaluation of deep sub-micron, fully-depleted silicon-on-insulator (FD-SOI) transistors at low temperatures SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The performance of 0.25, 0.3 and 0.35 mum fully-depleted SOI transistors is characterized between 77 and 300K. The behavior of device parameters such as drain current, mobility, transconductance, threshold voltage, subthreshold slope, and Early voltage is analyzed. The suitability of sub-micron FD-SOI devices is examined for low temperature operation as encountered in deep space exploration missions. The results indicate significant performance improvements with decreasing temperature down to 100K. A second effect dominates below this temperature, thus decreasing mobility and leading to other parameter degradations below 100K. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yuan, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 303-230, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 415 EP 419 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800050 ER PT S AU Stoica, A Keymeulen, D Duong, V Salazar-Lazaro, C AF Stoica, A Keymeulen, D Duong, V Salazar-Lazaro, C GP IEEE IEEE TI Automatic synthesis and fault-tolerant experiments on an evolvable hardware platform SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Outer solar system exploration and missions to comets and planets with severe environmental conditions require long-term survivability of space systems. This challenge has recently been approached with new ideas, such as using mechanisms for hardware adaptation inspired from biology. The application of evolution-inspired formalisms to hardware design and self-configuration lead to the concept of evolvable hardware (EHW). EHW refers to self-reconfiguration of electronic hardware by evolutionary/genetic reconfiguration mechanisms. The paper describes a fine-grained Field Programmable Transistor Array (FPTA) architecture for reconfigurable hardware, and its implementation on a VLSI chip. A first experiment illustrates automatic synthesis of electronic circuits through evolutionary design with the chip-in-the-loop. The chip is rapidly reconfigured to evaluate candidate circuit designs. A second, fault-tolerance experiment shows how evolutionary algorithms can recover functionality after being subjected to faults, by finding new circuit configurations that circumvent the faults. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Stoica, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 465 EP 471 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800056 ER PT S AU Lohn, JD Haith, GL Colombano, SP Stassinopoulos, D AF Lohn, JD Haith, GL Colombano, SP Stassinopoulos, D GP IEEE IEEE TI Towards evolving electronic circuits for autonomous space applications SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The relatively new field of Evolvable Hardware studies how simulated evolution can reconfigure, adapt, and design hardware structures in an automated manner. Space applications, especially those requiring autonomy, are potential beneficiaries of evolvable hardware. For example, robotic drilling from a mobile platform requires high-bandwidth controller circuits that are difficult to design. In this paper, we present automated design techniques based on evolutionary search that could potentially be used in such applications. First, we present a method of automatically generating analog circuit designs using evolutionary search and a circuit-construction language. Our system allows circuit size (number of devices), circuit topology, and device values to be evolved. Using a parallel genetic algorithm, we present experimental results for five design tasks. Second, we investigate the use of coevolution in automated circuit design. We examine fitness evaluation by comparing the effectiveness of four fitness schedules. The results indicate that solution quality is highest with static and coevolving fitness schedules as compared to the other two dynamic schedules. We discuss these results and offer two possible explanations for the observed behavior: retention of useful information, and alignment of problem difficulty with circuit proficiency. C1 NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 USA. RP Lohn, JD (reprint author), NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 USA. NR 23 TC 0 Z9 1 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 473 EP 486 PG 14 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800057 ER PT S AU LaBel, KA Barnes, CE Marshall, PW Marshall, CJ Johnston, AH Reed, RA Barth, JL Seidleck, CM Kayali, SA O'Bryan, MV AF LaBel, KA Barnes, CE Marshall, PW Marshall, CJ Johnston, AH Reed, RA Barth, JL Seidleck, CM Kayali, SA O'Bryan, MV GP IEEE IEEE TI A roadmap for NASA's radiation effects research in emerging microelectronics and photonics SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 5 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Electronics Radiation Characterization (ERC) project of the NASA Electronic Parts and Packaging (NEPP) Program is responsible for the radiation effects research on microelectronics and photonics for NASA. In this presentation, we present our roadmap for providing aid to NASA night projects, technology developers, and the aerospace community. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP LaBel, KA (reprint author), NASA, Goddard Space Flight Ctr, Code 562, Greenbelt, MD 20771 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 535 EP 545 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98J UT WOS:000165245800061 ER PT S AU Mandutianu, S AF Mandutianu, S GP IEEE IEEE TI Space networking-interacting in space communication networks SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Space missions always required reliable transfer of data between space and ground. With the advent of multi-spacecraft missions, the requirements extend to inter-spacecraft telecommunications. The network of telecommunication nodes has to provide communication relay and navigation support for a variety of science missions. From this point of view any spacecraft will be considered as just another communication node. One of the communication characteristics is that the communication nodes may be dynamically making and breaking links between them. The existing communication architectures use the ground stations as intermediate or even terminal nodes. An important technological problem is to configure the nodes so that they could establish the links whenever they are needed and also to provide them with the capability to track one another so that they could set up the communication channel between themselves. It is not always feasible to define in advance all the possible routes, in which case the route construction has to be done in real time for each specific configuration. There is an ongoing exchange of information and negotiation among the spacecraft and the ground, and possibly between the spacecraft themselves. The space telecommunication constraints, such as intermittent connectivity, limited signal strength and noise make data loss more serious than in ground networks. On the other hand, communication at a lower level of abstraction increases the probability of frequent exchanges, including associated data transfers. We address the issue of enabling computational technologies addressing both the requirements of communicating at a higher level of abstraction between heterogeneous ground and on-board systems and the requirements of space communication protocol standards. Higher level protocol layers are presented in the context of a distributed interactive multi-agent architecture simulating flight and ground software systems controlling and transmitting information in a space telecommunication network. The resulting agent protocol include higher level protocols for inter-agent communication at the knowledge or application level used to negotiate goals, as well as lower end protocols for space mission data transmissions. The asynchronous behaviors present in network management mean that complex interactions can occur. Multi-layered control architectures based on interacting agents seem appropriate, allowing for logical decomposition of the decision-making processes, reflecting the inherent distributed nature of this type of systems and support the need for intelligent control and robustness. This paper presents the use of a multi-agent system, emphasizing the interaction aspects of computational components and allowing for sharing higher-level information structures between components. This architectural approach allows for encapsulation of the main mission software functions and transparently ensures their interoperability. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mandutianu, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 193 EP 202 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000020 ER PT S AU Henry, MD Brinza, DE Mactutis, AT McCarty, KP Rademacher, JD vanZandt, TR Johnson, R Moses, S Musmann, G Kuhnke, F AF Henry, MD Brinza, DE Mactutis, AT McCarty, KP Rademacher, JD vanZandt, TR Johnson, R Moses, S Musmann, G Kuhnke, F GP IEEE IEEE TI NSTAR diagnostic package architecture and Deep Space One spacecraft event detection SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Deep Space One mission is demonstrating the long-duration use of an Ion Propulsion Subsystem (IPS). The NASA Solar Electric Propulsion Technology Applications Readiness Project developed the NSTAR Diagnostics Package (NDP) to monitor the effects of the IFS on the spacecraft environment. The NDP measures contamination, plasma characteristics, electric fields, and magnetic fields. This paper describes the NDP requirements, development process, and flight systems' functionality. NDP functionality exceeded expectations; it became an effective tool in the detection and diagnosis of spacecraft functionality and system anomalies. NDP detects hydrazine thruster firings (planned and not planned), ion engine gimbal stepper motor currents, solar array currents, spacecraft charging, as well as a number of other phenomena. Examples of selected ion engine and spacecraft signatures and their interpretations are discussed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Henry, MD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 293 EP 307 PG 15 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000030 ER PT S AU Malin, JT Kowing, J Schreckenghost, D Bonasso, P Nieten, J Graham, JS Fleming, LD MacMahon, M Thronesbery, C AF Malin, JT Kowing, J Schreckenghost, D Bonasso, P Nieten, J Graham, JS Fleming, LD MacMahon, M Thronesbery, C GP IEEE IEEE TI Multi-agent diagnosis and control of an air revitalization system for life support in space SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB An architecture of inter-operating agents has been developed to provide control and fault management for advanced life support systems in space. In this multi-agent architecture, cooperating autonomous software agents coordinate with human agents, to provide support in novel fault management situations. This architecture combines the Livingstone model-based mode identification and reconfiguration (MIR) system with elements of the 3T architecture for autonomous flexible command and control. The MIR software agent performs model-based state identification and fault diagnosis. MIR also identifies novel recovery configurations and the set of commands required to accomplish the recovery. The 3T procedural executive and the human operator use the diagnoses and recovery recommendations, and provide command sequencing. Human interface extensions have been developed to support human monitoring and control of both 3T and MIR data and activities. This architecture has been exercised for control and fault management of an oxygen production system for air revitalization in space. The software operates in a dynamic simulation testbed. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Malin, JT (reprint author), NASA, Lyndon B Johnson Space Ctr, 2101 NASA Rd 1,ER2, Houston, TX 77058 USA. NR 15 TC 2 Z9 2 U1 1 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 309 EP 326 PG 18 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000031 ER PT S AU DeCoste, D AF DeCoste, D GP IEEE IEEE TI Learning envelopes for fault detection and state summarization SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper discusses a data mining approach for overcoming common problems with the traditional red-line limit-checking approach to fault detection and state summarization. It essentially involves learning and adapting parametric functions which provide context-sensitive bounds on historic time-series engineering data. Such bounds are suitable as dynamic plug-in replacements for static red-line values. They enable significantly earlier detection while maintaining low false alarm rates. An example will be discussed from recent onboard tests of this technology during the NASA Deep Space I (DS1) mission. C1 CALTECH, Jet Prop Lab, Machine Learning Syst Grp, Pasadena, CA 91109 USA. RP DeCoste, D (reprint author), CALTECH, Jet Prop Lab, Machine Learning Syst Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 337 EP 344 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000033 ER PT S AU Hambaba, A Huff, E AF Hambaba, A Huff, E GP IEEE IEEE TI Multiresolution error detection on early fatigue cracks in gears SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID VIBRATION AB In this paper, we focused on early fatigue cracks in gears in a helicopter transmission test rig. The time synchronous average signal is transformed to different scale using wavelet transform. The wavelet vanishing moments can characterize the local signal singularities defined as local Holder exponent. At each level, one can extract from the signal its regularity: approximate the wavelet-transformed signal using the linear models: Autoregressive Moving Average (ARMA). The residual error is computed at each level. The final phase is the feature extraction from the residual error at each scale. The probability density function of the residual error is expanded into Hermite polynomial. The coefficients of this expansion are used as a feature vector for detection/estimation of the early fatigue cracks in gears. One can track the nonstationarity signal embedded in the residual error at each scale. C1 NASA, Ames Res Ctr, NRC, Moffett Field, CA 94035 USA. RP Hambaba, A (reprint author), NASA, Ames Res Ctr, NRC, MS 269-1, Moffett Field, CA 94035 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 367 EP 372 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000036 ER PT S AU Hambaba, A AF Hambaba, A GP IEEE IEEE TI Nonstationary statistical tests in time-scale space SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID TRANSIENT AB Detection and estimation of abrupt changes in a nonstationary environment is an important and challenging problem. A statistical test for selecting the order of a nonstationary AR model is presented based on wavelet vanishing moment and predictive least squares principle. The order of the nonstationary AR is estimated at a different resolution level, which makes the order reliable. Its confidence interval is also determined. The test is derived based on the order probability distribution of the wavelet approximation sequence. C1 NASA, Ames Res Ctr, NRC, Moffett Field, CA 94035 USA. RP Hambaba, A (reprint author), NASA, Ames Res Ctr, NRC, MS 269-1, Moffett Field, CA 94035 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 373 EP 379 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000037 ER PT S AU Montemerlo, MD AF Montemerlo, MD GP IEEE IEEE TI NASA's Cross Enterprise Technology Development Program (CETDP): A program in massive transition SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper describes the changes that NASA's Cross Enterprise Technology Development Program, which supports all of NASA's Enterprises. It is going from a program that was under the control of the NASA Centers to one which is broadly announced and peer reviewed, with NASA technologists competing with those of academia and industry. The issues which this change entails are delineated and initial ideas for solutions are provided. C1 NASA Headquarters, Washington, DC 20456 USA. RP Montemerlo, MD (reprint author), NASA Headquarters, Washington, DC 20456 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 561 EP 563 PG 3 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000053 ER PT S AU Krabach, T AF Krabach, T GP IEEE IEEE TI Breakthrough sensor technology for space exploration in the 21(st) century SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Krabach, T (reprint author), CALTECH, Jet Prop Lab, MS 179-224,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 565 EP 569 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000054 ER PT S AU Moore, C AF Moore, C GP IEEE IEEE TI Ultra-lightweight structures and space observatories thrust area SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Ultra-Lightweight Structures and Space Observatories thrust area is an element of NASA's Cross Enterprise Technology Development Program that develops revolutionary technology in structures, materials, and optical systems to enable new visions of the Earth and the Universe, and to expand the frontiers of exploration with lower cost and more capable spacecraft. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Moore, C (reprint author), NASA, Langley Res Ctr, MS 367, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 571 EP 574 PG 4 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000055 ER PT S AU Nainiger, JJ AF Nainiger, JJ GP IEEE IEEE TI Advanced power and on-board propulsion thrust area SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Nainiger, JJ (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS 500-203, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 575 EP 578 PG 4 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000056 ER PT S AU Bhasin, K AF Bhasin, K GP IEEE IEEE TI High rate data delivery thrust area SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB In this paper, a brief description of the high rate data delivery (HRDD) thrust area, its focus and current technical activities being carried out by NASA centers including JPL, academia and industry under this program is provided. The processes and methods being used to achieve active participation in this program are presented. The developments in space communication technologies, which will shape NASA enterprise missions in the 21st. century, are highlighted. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Bhasin, K (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS 54-2, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 579 EP 580 PG 2 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000057 ER PT S AU Prusha, SL AF Prusha, SL GP IEEE IEEE TI Rapid development and infusion: Program architectures and processes supporting faster, better, cheaper technology development SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Meeting Abstract CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Prusha, SL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 581 EP 581 PG 1 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000058 ER PT S AU Schwartz, PC Bold, MM AF Schwartz, PC Bold, MM GP IEEE IEEE TI Technology planning in a changing environment SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 6 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB To support the development of a technology investment planning process for the Cross-Enterprise Technology Development Program, CETDP, we have been conducting a benchmarking study of industry to identify best practices. This presentation will address technology planning and portfolio selection based on various methods and best business practices that are applicable for government technology planning. C1 NASA, Goddard Space Flight Ctr, Beltsville, MD 20705 USA. RP Schwartz, PC (reprint author), NASA, Goddard Space Flight Ctr, NTPIO Code 710, Beltsville, MD 20705 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 583 EP 586 PG 4 WC Engineering, Aerospace SC Engineering GA BQ98K UT WOS:000165246000059 ER PT S AU Carpenter, JR AF Carpenter, JR GP IEEE IEEE TI A preliminary investigation of decentralized control for satellite formations SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A distributed satellite formation consisting of n nodes interconnected via a communications network could be controlled using a decentralized controller framework that operates in parallel over the network. For such problems, a solution that minimizes data transmission requirements, in the context of linear-quadratic control theory, was given by Speyer [1]. An investigation of the feasibility of such an approach to satellite formation flying is currently being undertaken, in the context of efforts sponsored by NASA and the Air Force to develop architectures, strategies, and control approaches for various proposed distributed satellite missions. Among the issues under investigation are the effects of command and data handling system and communications channel noise and latency. For example, it is likely that the measurement devices and/or their associated command and data handling systems may provide asynchronous and/or non-simultaneous measurement data. It is also probable that transmission of the data between nodes could be delayed one or more sampling periods and/or interrupted for extended intervals. Furthermore, since it is not possible to create a noise-free communications channel, errors in the transmitted data will be introduced at the level of the network, in addition to errors introduced at the measurement and state transition levels. An additional difficulty is that, in general, nonlinearities in the dynamics and measurements of the distributed satellite control problem require the use of ad-hoc procedures such as the extended Kalman filter. Therefore, a simulation methodology is adopted for the study of the aforementioned issues in this work. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Carpenter, JR (reprint author), NASA, Goddard Space Flight Ctr, Code 572, Greenbelt, MD 20771 USA. NR 12 TC 3 Z9 3 U1 0 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 63 EP 74 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200008 ER PT S AU Bell, DJ Cesarone, R Ely, T Edwards, C Townes, S AF Bell, DJ Cesarone, R Ely, T Edwards, C Townes, S GP IEEE IEEE TI Mars Network: A Mars orbiting communications & navigation satellite constellation SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Mars has become the focus of an unprecedented series of missions spanning many years, involving numerous nations and evolving from robotic to human exploration. Elements will be dispersed widely in longitude and latitude over the surface of Mars. Some surface elements like revers, balloons and airplanes will be mobile. Other elements like sample canisters will orbit Mars. Finally manned sites will require broadband, 24hr connectivity to earth. The challenge has been to develop an architecture and technology roadmap that will anticipate the needs of this evolving mission set. NASA's Jet Propulsion Laboratory has begun development of this architecture and its associated technologies. For cost reasons, the early phases of this constellation will employ small spacecraft that ride as an auxiliary payloads on Ariane launches. A properly designed constellation of six or fewer spacecraft in low altitude, 800km, orbit around Mars is capable of providing significant global communications and navigation performance: 100's of Mbits per Martian day from elements at any location on the Martian surface. 10m accuracy position fix to a surface element located anywhere on the planet in an average time of 2 hours or less. C1 NASA, Jet Prop Lab, Pasadena, CA 91100 USA. RP Bell, DJ (reprint author), NASA, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91100 USA. NR 8 TC 3 Z9 3 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 75 EP 88 PG 14 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200009 ER PT S AU Berner, JB Kayalar, S Perret, JD AF Berner, JB Kayalar, S Perret, JD GP IEEE IEEE TI The NASA Spacecraft Transponding Modem SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A new deep space transponder is being developed by the Jet Propulsion Laboratory for NASA. The Spacecraft Transponding Modem (STM) implements standard transponder functions and some of the command and telemetry channel service functions that have resided in spacecraft Command/Data Subsystems. The STM tracks an X-band uplink signal and provides both X-band and Ka-band downlinks, either coherent or noncoherent with the uplink. A command detector is integrated into the STM, along with a codeblock processor and a hardware command decoder. The STM provides Reed-Solomon coding, convolutional coding, and Turbo coding for downlink telemetry. The downlink symbol rates can be linearly ramped to match the G/T curve of the receiving station. Data rates range from 5 bits per second (bps) to 24 Mbps, with three modulation modes provided: subcarrier, biphase-l direct on carrier, and Offset-QPSK. Standard turn around ranging, regenerative pseudo-noise ranging capability, and Differential One-way Ranging (DOR) tones are provided. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Berner, JB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 0 Z9 5 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 195 EP 209 PG 15 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200020 ER PT S AU Bonitz, RG Nguyen, TT Kim, WS AF Bonitz, RG Nguyen, TT Kim, WS GP IEEE IEEE TI The Mars Surveyor '01 Rover and Robotic Arm SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Mars Surveyor 2001 Lander will carry with it both a Robotic Arm and Rover to support various science and technology experiments. The Marie Curie Rover, the twin sister to Sojourner Truth, is expected to explore the surface of Mars in early 2002. Scientific investigations to determine the elemental composition of surface rocks and soil using the Alpha Proton X-Ray Spectrometer (APXS) will be conducted along with several technology experiments including the Mars Experiment on Electrostatic Charging (MEEC) and the Wheel Abrasion Experiment (WAE). The Rover will follow uplinked operational sequences each day, but will be capable of autonomous reactions to the unpredictable features of the Martian environment. The Mars Surveyor 2001 Robotic Arm will perform rover deployment, and support various positioning, digging, and sample acquiring functions for MECA (Mars Environmental Compatibility Assessment) and Mossbauer Spectrometer experiments. The Robotic Arm will also collect its own sensor data for engineering data analysis. The Robotic Arm Camera (RAC) mounted on the forearm of the Robotic Arm will capture various images with a wide range of focal length adjustment during scientific experiments and rover deployment. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bonitz, RG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 13 TC 0 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 235 EP 246 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200023 ER PT S AU Volpe, R Baumgartner, E Schenker, P Hayati, S AF Volpe, R Baumgartner, E Schenker, P Hayati, S GP IEEE IEEE TI Technology development and testing for enhanced Mars Rover Sample Return Operations SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID SURFACE AB This paper describes several Jet Propulsion Laboratory research efforts being conducted to support Mars sample return in the coming decade. After describing the 2003/05 mission scenario, we provide an overview of new technologies emerging from three complementary research efforts: Long Range Science Rover, Sample Return Rover, and FIDO Rover. The results show improvements in planning, navigation, estimation, sensing, and operations for small revers operating in Mars-like environments. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Volpe, R (reprint author), CALTECH, Jet Prop Lab, Mailstop 198-219, Pasadena, CA 91109 USA. NR 16 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 247 EP 257 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200024 ER PT S AU Dvorak, D Rasmussen, R Reeves, G Sacks, A AF Dvorak, D Rasmussen, R Reeves, G Sacks, A GP IEEE IEEE TI Software architecture themes in JPL's Mission Data System SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The rising frequency of NASA mission launches has highlighted the need for improvements leading to faster delivery of mission software without sacrificing reliability. In April 1998 Jet Propulsion Laboratory (JPL) initiated the Mission Data System (MDS) project to rethink the mission software lifecycle-from early mission design to mission operation-and make changes to improve software architecture and software development processes. As a result, MDS has defined a unified flight, ground, and test data system architecture for space missions based on object-oriented design, component architecture, and domain-specific frameworks. This paper describes several architectural themes shaping the MDS design and how they help meet objectives for faster, better, cheaper mission software. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Dvorak, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 259 EP 268 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200025 ER PT S AU Krasner, SM AF Krasner, SM GP IEEE IEEE TI A reusable state-based guidance, navigation and control architecture for planetary missions SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB NASA's Jet Propulsion Laboratory has embarked on the Mission Data System (MDS) project to produce a reusable, integrated flight and ground software architecture. This architecture will then be adapted by future JPL planetary projects to form the basis of their flight and ground software. The architecture is based on identifying the states of the system under consideration. States include aspects of the system that must be controlled to accomplish mission objectives, as well as aspects that are uncontrollable but must be known. The architecture identifies methods to measure, estimate, model, and control some of these states. Some states are controlled by goals, and the natural hierarchy of the system is employed by recursively elaborating goals until primitive control actions are reached. Fault tolerance emerges naturally from this architecture. Failures are detected as discrepancies between state estimates and model-based predictions of state. Fault responses are handled either by re-elaboration of goals, or by failures of goals invoking re-elaboration at higher levels. Failure modes are modelled as possible behaviors of the system, with corresponding state estimation processes. Architectural patterns are defined for concepts such as states, goals, and measurements. Aspects of state are captured in a state-analysis database. Unified Modelling Language (UML) is used to capture mission requirements as Use Cases and Scenarios. Application of the state-based concepts to specific states is also captured in UML, achieving architectural consistency by adapting base classes for all architectural patterns. Within the Guidance, Navigation and Control domain of MDS, work has focussed in three areas: (1.) Re-engineering and re-implementation of legacy Navigation systems within an object-oriented structure that is reusable from mission to mission and common between flight and ground systems; (2.) Identification of states and mission activities which are common across multiple missions; (3.) Exploitation of commonality between Attitude Control and Navigation functions, which have historically been separated in previous JPL missions. These areas will be demonstrated on a simulated reference spacecraft and mission and then adapted by customer missions. Early deliveries will have levels of autonomy similar to existing JPL spacecraft, in order to demonstrate the applicability of the state-based concepts. This architecture should greatly simplify the implementation of existing levels of autonomy and should support significantly increased autonomy in future deliveries. Studies are ongoing to determine the mission requirements for highly integrated attitude and trajectory control functions, leading eventually to "6-degrees-of-freedom" control. These functions will eventually be implemented within the MDS architecture. The first customer mission is Europa Orbiter, to be followed by Pluto/Kuiper and Solar Probe. Discussions are also ongoing to adapt MDS for the Space Interferometry Mission and for control of the Deep Space Network. First prototype demonstration of a simple detumble capability was demonstrated in November 1999. As of December, 1999, work was being done on the next increment, controlling attitude to bring the Sun into the Sun-sensor field-of-view. Subsequent deliveries will include increasing capability leading to a delivery to the Europa Orbiter project in Nov. 2001. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Krasner, SM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 269 EP 275 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200026 ER PT S AU Watzin, J AF Watzin, J GP IEEE IEEE TI The Triana Mission - Next generation systems architecture ready for flight SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB NASA's Triana Mission is the first to take full advantage of the powerful capabilities offered by modern digital electronics and comprehensive software architecture. Not only is the performance of these miniature systems well beyond that of their bulky predecessors, but the time to configure them for a particular mission has been dramatically reduced as well. As a result, the cost of these implementations is just a fraction of previous missions. This deep space Earth and solar science platform touts highly autonomous, 3-axis stabilized performance for only $77M. In just 21 months time, the Triana observatory will have gone from conceptual design to flight readiness, being launched by the Space Transportation System (STS) in early 2001. After deployment in Low Earth Orbit (LEO), Triana will boost itself into a trajectory to the LI libration point approximately 1.5 million kilometers from Earth. There it will make observations of space weather, Earth climatic behavior, and whole Earth radiometry. The budget includes the development of the spacecraft, 5 scientific instruments, deployable booms and solar arrays, a hydrazine propulsion module, a new upper stage system based on the Thiokol Star-48 kick motor, all that goes with launching from the manned STS, and 2 years of continuous mission operations and scientific data analysis. The work is being implemented as an in-house project at NASA Goddard Space Flight Center (GSFC), capitalizing on the extensive design, development, and operational experience that has been acquired during the past decade on the Small Explorer (SMEX) Project, Hitchhiker/Spartan Project, and the Hubble Space Telescope servicing missions. This paper will describe the novel approach taken to implement this mission, commenting on the technical architecture as well as the processes used. Experiences to date on the development status will also be discussed. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Watzin, J (reprint author), NASA, Goddard Space Flight Ctr, Code 474,Bldg 8,Room 400, Greenbelt, MD 20771 USA. NR 2 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 277 EP 285 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200027 ER PT S AU Wilcox, BH Jones, RM AF Wilcox, BH Jones, RM GP IEEE IEEE TI The MUSES-CN nanorover mission and related technology SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Recent advances in microtechnology and mobile robotics have made it feasible to create extremely small automated or remote-controlled vehicles which open new application frontiers. One of these possible applications is the use of nanorovers (robotic vehicles with a mass of order 1 Kg or less) in planetary exploration. NASA and Japan's Institute of Space and Astronautical Science (ISAS) are cooperating on the first mission to collect samples from the surface of an asteroid and return them to Earth for in-depth study. The ISAS MUSES-C mission will be launched on a Japanese launch vehicle in July 2002 from Japan toward a redezvous with the asteroid 1989ML in September 2003. A NASA-provided nanorover will conduct in-situ measurements on the surface. Asteroid samples will be returned to Earth by MUSES-C via a parachute-borne recovery capsule in June 2006. This paper describes the rover being created for this mission and related technology developments. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. RP Wilcox, BH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91009 USA. NR 5 TC 0 Z9 0 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 287 EP 295 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200028 ER PT S AU Chau, S Luong, H Charlan, W Fukuhara, R Holmberg, E Jones, P Pixler, G AF Chau, S Luong, H Charlan, W Fukuhara, R Holmberg, E Jones, P Pixler, G GP IEEE IEEE TI The implementation of a COTS based fault tolerant avionics bus architecture SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB X2000 is a technology program at the Jet Propulsion Laboratory to develop enabling technologies for future flight missions at affordable cost. The cost constraints mandate the use of commercial-off-the-shelf (COTS) components and standards in the X2000 multimission avionics system architecture. The X2000 has selected two commercial bus standards, the IEEE 1394 and (IC)-C-2, as the avionics system buses. These two buses work together to provide the performance, scalability, low power consumption, and fault tolerance required by long life deep space missions. In this paper, we report our approach in implementing a fault-tolerant bus architecture for the X2000 avionics system using these two COTS buses. The system approach is described first. Then, the focus of the rest of the discussion is on the implementation of two ASICs, Digital I/O (DIO) and Mixed Signal I/O (MSIO) ASICs, which are the key components of this COTS based fault-tolerant bus architecture. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Chau, S (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 297 EP 305 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200029 ER PT S AU Horowitz, SJ Goldsmith, D AF Horowitz, SJ Goldsmith, D GP IEEE IEEE TI Structure and evolution of the universe - 21st century missions SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Structure and Evolution of the Universe (SEU) science theme at NASA centers on four cosmological quests: To comprehend how matter in the universe evolved from formlessness into the structural complexity of galaxies and galaxy clusters To probe the ultimate limits of physics by searching for new behaviors of space, time, and matter close to black holes To understand how matter behaves under extreme conditions, producing exotic objects such as quasars and gamma-ray bursters, and ripples of the space-time fabric called gravity waves To study how stars create new elements, and to follow the cycles of mass and energy in stellar evolution, from starbirth in giant interstellar clouds to the violent explosions that end some stars' lives but lead again to star birth This paper discusses the variety of missions in the SEU Theme, demonstrating how all the full electromagnetic spectrum must be surveyed to address these quests. C1 NASA, Goddard Space Flight Ctr, Off Associate Director, Greenbelt, MD 20771 USA. RP Horowitz, SJ (reprint author), NASA, Goddard Space Flight Ctr, Off Associate Director, Code 101, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 307 EP 321 PG 15 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200030 ER PT S AU Stetson, D AF Stetson, D GP IEEE IEEE TI New horizons in solar system exploration SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB A revised and updated Roadmap for the Exploration of the Solar System contains mission recommendations and has been provided as input to the NASA Office of Space Science strategic planning process. The recommended missions will continue the program's emphasis on understanding the origin and possible existence of life in the solar system Missions are summarized as components of four exploration programs, three of which are continuing and one of which is a recommended new program. Key capabilities required for these new missions are also identified. C1 Jet Prop Lab, Solar Syst Explorat Off, Pasadena, CA 91109 USA. RP Stetson, D (reprint author), Jet Prop Lab, Solar Syst Explorat Off, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 323 EP 328 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200031 ER PT S AU Calabrese, MA Poland, AI Caruso, PS VanSant, JT McNutt, RL Wallace, RA AF Calabrese, MA Poland, AI Caruso, PS VanSant, JT McNutt, RL Wallace, RA GP IEEE IEEE TI NASA Sun-Earth Connection Program strategic planning & technology requirements (2000-2025) SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Sun-Earth Connection (SEC) Program is one of NASA's four major science themes in the Office of Space Science (OSS). The goal of the SEC Program is to understand our changing sun and its effects on the solar system, life and society. This goal is addressed through four fundamental Quests with supporting campaigns composed of a sequence of missions making new measurements and providing a variety of observations from many vantage points to address the dynamic phenomena in the Sun-Earth system. These missions are planned to be enabled by technology development in key areas including advanced propulsion, spacecraft technology, scientific instrumentation, and information architecture. The application of the knowledge gained from the SEC program will provide an understanding of how solar variability affects the performance and operational lifetime of space hardware, the safety of humans in the near-Earth space environment or on extended exploration missions, and short and long term terrestrial climate patterns. The application of this understanding is presently being addressed in a SEC Initiative entitled "Living With A Star". C1 NASA, Goddard Space Flight Ctr, Off Associate Director, Greenbelt, MD 20771 USA. RP Calabrese, MA (reprint author), NASA, Goddard Space Flight Ctr, Off Associate Director, Code 101, Greenbelt, MD 20771 USA. NR 3 TC 0 Z9 0 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 329 EP 339 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200032 ER PT S AU Price, H Cramer, K Doudrick, S Lee, W Matijevic, J Weinstein, S Lam-Trong, T Marsal, O Mitcheltree, R AF Price, H Cramer, K Doudrick, S Lee, W Matijevic, J Weinstein, S Lam-Trong, T Marsal, O Mitcheltree, R GP IEEE IEEE TI Mars Sample Return spacecraft systems architecture SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Mars Sample Return mission plans to collect sets of samples from two different sites on Mars and return them to Earth in 2008. The mission consists of 15 different vehicles and spacecraft plus two launch vehicles, with elements being provided by the U.S, France, and Italy. These vehicles include two U.S. provided Landers, each with a sample collection Rover, Mars Ascent Vehicle, and an Orbiting Sample satellite. France is providing the sample return Orbiter which carries a U.S payload for sample detection and capture plus two Earth Entry Vehicles for landing the samples on Earth. The Orbiter also delivers four NetLanders to Mars for performing unique surface science. Significant in-situ science is included. New technologies are being developed to aerocapture into Mars orbit, to collect and safeguard the samples, to launch the samples into Mars orbit, and to enable autonomous Mars orbit rendezvous and capture for return to Earth. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Price, H (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 1 Z9 3 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 357 EP 375 PG 19 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200034 ER PT S AU Gershman, R Nilsen, E Sweetser, T AF Gershman, R Nilsen, E Sweetser, T GP IEEE IEEE TI Venus surface sample return SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB In cooperation with NASA's Solar System Exploration Subcommittee (SSES) the Jet Propulsion Laboratory (JPL) is conducting a series of studies to assess the feasibility of planetary science missions proposed for launch in the 2006-2010 time frame and to prioritize technology development steps that will enable these missions. Until recently the return of sample material from the surface of Venus was widely considered to be beyond the technological and financial capabilities of the NASA Space Science Program for this time frame, but technological and programmatic advances may now have brought such a mission within reach[1]. This paper describes the results of a study to investigate the feasibility of various options proposed for a Venus Surface Sample Return (VSSR) Mission and to develop a mission concept to be considered in NASA's strategic planning. Included will be discussions of the science objectives, the major system and subsystem trade-offs, and a preliminary mission concept. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gershman, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 301-170U, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 377 EP 384 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200035 ER PT S AU Wallace, RA Ayon, JA Sprague, GA AF Wallace, RA Ayon, JA Sprague, GA GP IEEE IEEE TI Interstellar probe mission/system concept SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB NASA's Interstellar Program was begun in the Spring of 1999 after a year of advanced mission and program planning activities, reported previously in a paper delivered at the 1999 IEEE Aerospace Conference. Summarized here is the progress towards defining the first mission in the Interstellar Program: Interstellar Probe (ISP). This mission will be the first to probe the interstellar medium with a complete set of scientific instruments designed for such exploration and is expected to be a precursor and a significant testbed for technologies being developed for eventual travel to the nearest star. Exploration of the interstellar medium is the objective of the Interstellar Probe mission. The interface between our solar system and galaxy defines the cross over into the interstellar medium and is the minimum target distance, thought to be beyond 125 AU. A mission requirement, therefore, is to reach 200 AU in fifteen years or less with a scientifically capable payload package. Time and distance are key design requirements, and advanced propulsion technology is a key enabler of the Interstellar Probe mission. Another key mission goal is to launch in the 2010 time period; thereby setting associated advanced technology goals of readiness by about 2007. Solar sail propulsion has been baselined for the mission design concept. Key trades are sail technology development requirements as a function of trip time to 200 AU and the payload mass that can be delivered and operated at that distance. This paper provides strawman payload and measurement requirements, technology and mission trade information, and a baseline system design, including a configuration concept. Alternate technology options are described. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wallace, RA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 385 EP 396 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200036 ER PT S AU Jones, JA AF Jones, JA GP IEEE IEEE TI Innovative balloon buoyancy techniques for atmospheric exploration SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Until quite recently, the only practical means to control balloon buoyancy, and thus altitude, required consuming large amounts of fuel or the limited venting of helium balloons and/or dropping of ballast. Recently at JPL, novel, long-life, balloon buoyancy techniques have been developed that for the first time allow balloons to float in the primarily hydrogen atmospheres of Jupiter, Saturn, Uranus, and Neptune (using ambient fill-gas) and, by using renewable energy sources, allow multiple controlled landings on Venus (using atmospheric temperature differences), Mars (using solar heat), Than (using Radioisotope Thermal Generator (RTG) heat), and Earth (using planet radiant heat). A test program has been initiated at JPL to confirm these basic new buoyancy principles. The Earth balloon work will be performed in conjunction with Goddard Space Flight Center (GSFC) to apply these techniques to increase controllability of scientific terrestrial balloons. These novel techniques may enable many exciting, yet Economical and practical scientific balloon missions to seven planets and one moon in our own solar system, and, in fact, may eventually be the basis for in situ exploration of planets in other solar systems. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jones, JA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 397 EP 402 PG 6 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200037 ER PT S AU Chmielewski, AB Moore, C Howard, R AF Chmielewski, AB Moore, C Howard, R GP IEEE IEEE TI The Gossamer initiative SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Gossamer Spacecraft Initiative is a new NASA program to begin long-range development of enabling technologies for very large, ultra-lightweight structures and apertures. Large apertures include optical, infrared and submillimeter telescopes, "photon buckets" for optical communications and "non-coherent" imaging, solar concentrators, and radio frequency antennas. Developments in large ultra-light structures will be focused on one of their most challenging applications - solar sails. Sail structures will include both 3-axis stabilized and spinning. Gossamer spacecraft technology will eventually allow NASA to undertake bold new missions of discovery, such as searching for the signs of life on planets orbiting nearby stars, and sailing through space on beams of light to places beyond our solar system. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Chmielewski, AB (reprint author), Jet Prop Lab, Pasadena, CA 91109 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 429 EP 438 PG 10 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200042 ER PT S AU Chmielewski, AB Noca, M Ulvestad, J AF Chmielewski, AB Noca, M Ulvestad, J GP IEEE IEEE TI ARISE antenna SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Supermassive black holes are among the most spectacular objects in the Universe, and are laboratories for physics in in extreme conditions. Understanding the physics of massive black holes and related phenomena is a primary goal of the ARISE mission. The scientific goals of the mission are described in detail on the ARISE web site http://arise.jpl.nasa.gov and in the ARISE Science Goals document [1, 2]. The following paper, as the title suggests, is not intended to be a comprehensive description of ARISE, but deals only with one aspect of the ARISE mission - the inflatable antenna which is the key element of the ARISE spacecraft. The spacecraft due to the extensive reliance on inflatables may be considered as the first generation Gossamer spacecraft. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Chmielewski, AB (reprint author), Jet Prop Lab, Pasadena, CA 91109 USA. NR 3 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 439 EP 445 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200043 ER PT S AU Garner, CE AF Garner, CE GP IEEE IEEE TI Large area sail design concepts SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID SOLAR SAIL AB Mission concepts to several hundred AU and beyond are under study at NASA Marshall Space Flight Center (MSFC) and NASA Jet Propulsion Laboratory (JPL). The preliminary results of these mission studies have identified solar sails as one of the promising propulsion technologies for making these ambitious precursor and interstellar missions a reality. This paper presents solar and beamed energy sail design concepts to achieve the performance requirements identified in preliminary interstellar exploration technology roadmaps which include nearer-term interstellar precursor missions to several hundred AU and beamed power missions to Alpha Centauri and beyond. The baseline solar sail design for an interstellar probe (ISP) mission to the near-interstellar medium assumes an areal density of 1 g/m(2) (including film and structure), and a diameter of similar to 410 m. Missions to the stars will require very large sails with areal densities approaching 0.1 g/m(2). C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Garner, CE (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 24 TC 1 Z9 1 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 447 EP 457 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200044 ER PT S AU Delin, KA Jackson, SP AF Delin, KA Jackson, SP GP IEEE IEEE TI Sensor web for in situ exploration of gaseous biosignatures SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID MICROBIAL MAT AB A Sensor Web is a system of intra-communicating spatially distributed sensor pods that can be deployed to monitor and explore new environments. By its very nature, the Sensor Web provides spatio-temporal data in a form consistent with that needed for environment modeling and represents a new paradigm for in situ monitoring and exploration. For example, a wireless web of scattered sensor pods on the Martian surface is an ideal way to pursue gaseous biosignature searches. Sensor Web climate and agricultural monitoring on Earth (particularly when coupled with remote measurements) characterize significant commercial opportunities for this technology. Recent laboratory demonstrations at the Jet Propulsion Laboratory (JPL) have shown the potential of current Sensor Web technology. These demonstrations are leading to a JPL effort to field a Sensor Web in Baja California to examine gaseous biosignatures from the microbial mats there. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Delin, KA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 4 Z9 4 U1 0 U2 3 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 465 EP 472 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200046 ER PT S AU Rodgers, D Gilmore, M Sweetser, T AF Rodgers, D Gilmore, M Sweetser, T GP IEEE IEEE TI Venus sample return a hot topic ... SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Within the Solar System, Venus presents a set of unique challenges to obtaining samples and returning them to Earth. High temperatures, a thick corrosive atmosphere and poorly characterized terrain are some obvious examples. Our only knowledge of the surface and atmosphere is from Radar images and the data from Soviet probes. A point design now exists for a single launch mission to return Venusian samples massing about 100g. This paper discusses this mission, addressing the science return, how some of Venus' attributes can be used to advantage and what technologies will be needed to make this mission a reality. It also explores possible future directions to make the mission more affordable. C1 CALTECH, Jet Prop Lab, JPL Adv Project Design Team, Ctr In Situ Sci & Sample Return, Pasadena, CA 91109 USA. RP Rodgers, D (reprint author), CALTECH, Jet Prop Lab, JPL Adv Project Design Team, Ctr In Situ Sci & Sample Return, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Gilmore, Martha/G-5856-2011 NR 13 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 473 EP 483 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200047 ER PT S AU Kerzhanovich, V Balaram, J Campbell, B Cutts, JA Gershman, R Greeley, R Hall, JL Klaasen, K Zimmerman, W Hansen, D AF Kerzhanovich, V Balaram, J Campbell, B Cutts, JA Gershman, R Greeley, R Hall, JL Klaasen, K Zimmerman, W Hansen, D GP IEEE IEEE TI Venus Aerobot Multisonde Mission: Atmospheric relay for imaging the surface of Venus SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Robotic exploration of surface of Venus presents many challenges because of the thick atmosphere, high surface pressure and high temperature. The Venus Aerobot Multisonde Mission (VAMuS) concept addresses these challenges by using a robotic balloon or aerobot to deploy a number of short lifetime probes or sondes to acquire images of the surface, perform atmospheric measurements and measure a fine composition of the atmosphere. Deployment of sondes from an aerobot has two compelling advantages it permits more precise deployment than with direct entry and it makes it possible to acquire high-rate data from the sondes using very low power transmitters because of the short communications ranges of a few tens of kilometers. Sonde data stored on the aerobot can be transmitted to Earth at much lower rates because the aerobot will operate for at least a week in the Venusian atmosphere. This paper describes the Venus Aerobot Multisonde concept, which is a foundation for Venus Exploration of Volcanoes and Atmosphere (VEVA), a proposal to NASA's Discovery program. Besides discussion of aerobot performance, the paper deals with communications, navigation and drop sonde instrumentation issues, which are key factors for mission success. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kerzhanovich, V (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 485 EP 491 PG 7 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200048 ER PT S AU Park, YH AF Park, YH GP IEEE IEEE TI Mars Volatiles and Climate Surveyor (MVACS) SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Mars Volatiles and Climate Surveyor (MVACS) is an integrated payload on the Mars Polar Lander (MPL) launched on January 3, 1999. The MPL will land on Mars on December 3, 1999. MVACS consists of Surface Stereo Imager (SSI), Robotic Arm (RA) including Robotic Arm Camera (RAC), Meteorology Package (MET) and Thermal and Evolved Gas Analyzer (TEGA). The major science objective of MVACS is to study when the Mars volatiles are now and what determines the behavior of Mars volatiles over time. The MVACS will accomplish most science activities during 3 months primary mission and will conduct an extended mission if the Lander continues to function. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Park, YH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 301-335, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 501 EP 505 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200050 ER PT S AU Steltzner, AD Nasif, AK AF Steltzner, AD Nasif, AK GP IEEE IEEE TI Anchoring technology for in situ exploration of small bodies SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID PENETRATION; TARGETS; PROJECTILES AB Comets, asteroids and other small bodies found in the solar system do not possess enough gravity to ensure spacecraft contact forces sufficient to allow many types of in situ science, such as core or surface sampling. Some method of providing sufficient contact force must be used for successful in situ exploration. A range of possible anchoring technologies for use with small bodies is discussed and a specific technology developed in greater detail. This anchoring technology is based on a high energy, gas driven telescoping spike that has demonstrated success in anchoring into targets with a wide range of material properties. It is expected to be successful in anchoring to bodies with surface properties that may range in unconfined compressive strengths from 10 kPa to 10 MPa. The physics of the device and the penetration mechanics of the anchoring are discussed. The development of the hardware for NASA's now cancelled ST4/Champollion mission is detailed and finally, results from the test and verification program for the ST4/Champollion spacecraft anchoring mechanism are discussed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Steltzner, AD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 301-350, Pasadena, CA 91109 USA. NR 8 TC 4 Z9 6 U1 1 U2 3 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 507 EP 518 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200051 ER PT S AU George, T Buehler, M Feldman, J Rockstad, H Bridges, N Wilcox, J AF George, T Buehler, M Feldman, J Rockstad, H Bridges, N Wilcox, J GP IEEE IEEE TI Electron beam enabled surface composition, charge, and adsorbed gas determination SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The Human Exploration and Development of Space Roadmap calls for Human Missions to Mars and other planets in the 2010 to 2023 timeframe. This paper describes a proposal written in response to the Announcement of Opportunity (A099-HEDS-01) for definition studies preparing for the human exploration of Mars. Specifically, the proposal addressed the call for the development of innovative instrument concepts aimed at studying soil, dust, and environmental interactions for 2005 Mission Opportunities. The objective of the proposed study was to determine the feasibility, under simulated Martian ambient conditions, of a suite of miniature instruments pet-forming correlated measurements of sample surfaces. A novel Atmospheric Electron X-ray Spectrometer (AEXS), an optical microscope capable of producing low magnification images, an electrometer, and a fiber optic oxygen sensor fitted with a resistive heater comprised the proposed instrument suite. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP George, T (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 302-306, Pasadena, CA 91109 USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 519 EP 537 PG 19 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200052 ER PT S AU Zimmerman, W AF Zimmerman, W GP IEEE IEEE TI Extreme electronics for in situ robotic/sensing systems SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB NASA's desire to study and characterize the solar system and small bodies like comets and asteroids will be done by in situ robotic systems in the near term. Work has already begun on the design of Mars and Europa mole penetrators, ultrasonic coring systems for Venus. and corers for comet nucleus sampling. Along with these in situ sampling systems come miniature science instruments that allow samples to be imaged microscopically, or sensor suites that break down and examine the chemical composition and DNA of samples. Both sample acquisition and instruments will be exposed to extreme radiation, temperatures, corrosion, or pressures. This paper describes these intended extreme mission environments, and discusses technologies being developed to enable systems to operate in extreme conditions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Zimmerman, W (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 26 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 539 EP 546 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200053 ER PT S AU Kerzhanovich, VV Cutts, JA AF Kerzhanovich, VV Cutts, JA GP IEEE IEEE TI Aerobots in planetary exploration SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Robotic Balloons (Aerobots) may significantly change the future of in situ planetary exploration. On Mars, the aerobots can fill the gap in resolution/coverage between the orbiters and revers. Powered aerobots (airships) can make controlled,global flights for high-resolution radar, visible, infrared, thermal, magnetic, and neutron mapping; they can be used for deployment of network of surface stations. Tethered balloons could provide ultra high-resolution imaging of local areas for navigation of revers and data relay to the main lander station. Solar-heated balloons could be used as low atmospheric decelerators for low-speed landing. In more distant future the airships could be used for human transportation. On Venus, aerobots may serve as the scientific platforms for the in situ atmospheric measurement and for study of atmospheric circulation. They can be used to drop imaging and deep sounding probes at sites of interest and to acquire and relay high-rate imaging data. Balloons technology is enabling for any Venus surface sample return mission. On Titan, powered aerobots can perform long duration low-altitude global flight for surface mapping, in situ atmospheric measurements, deployment of landers and revers for in situ surface studies. Aerobots can also be used for long-duration atmospheric studies of the outer planets. Aerobot technologies have become more mature in recent years due to progress in development of envelope materials, and envelope design driven primarily by stratospheric applications. Technologies for deployment and inflation, navigation, control, communication and power are also developing rapidly in response to planetary applications. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kerzhanovich, VV (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 547 EP 555 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200054 ER PT S AU Smith, JH AF Smith, JH GP IEEE IEEE TI Low-cost robotics for space exploration: A probabilistic trade space for biomorphic exploration devices SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB During the next decade, numerous in-situ sampling missions are planned to a variety of planets, moons, asteroids, and comets. A goal of these missions is to understand the origin and evolution of the planetary system and the physical and chemical processes that led to the evolution of life. Among the variety of new technologies needed for such exploration are small, highly mobile, autonomous and relatively inexpensive platforms known as biomorphic explorers. These miniaturized robotic devices will be particularly valuable for study and exploration of the surfaces of planets, moons, and small bodies. Large numbers of small, dexterous explorers could seek out and deploy sensors in places not accessible by larger rover vehicles or landers. The low cost of such microdevices would also enable the exploration of heretofore high-risk and dangerous landing sites excluded by large, more expensive systems. This paper addresses the problem of determining the tradeoff space between the likelihood of each device achieving its stated science goal and the number of units needed to obtain the minimum required mission probability of success. Probabilistically, to a first order, the paper addresses the question, "If the probability of a single unit achieving its goal is x%, what is the required number of units to achieve 95% probability of mission success?" The impacts of cost are discussed using a linear fixed and variable cost model to derive the optimum number of units for deployment. The issues relevant to the analysis and deployment of multiple, low cost, microelectronic and electromechanicaI devices (MEMs) biomorphic explorers and the corresponding risks are also presented. A simple decision tree is presented with a parametric cost model to illustrate the potential to address risk and cost trade-offs. Three-dimensional visualizations of the probabilistic trade space are presented to illustrate these issues. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Smith, JH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 301-165, Pasadena, CA 91109 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 567 EP 571 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200056 ER PT S AU Minning, CP Buehler, MG Fujita, T Lansing, F Man, G Aljabri, A Stevens, C AF Minning, CP Buehler, MG Fujita, T Lansing, F Man, G Aljabri, A Stevens, C GP IEEE IEEE TI Technology selection and validation: New millennium flight projects SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB NASA's New Millennium Program (NMP) was created to accelerate the insertion of advanced space-related technologies into future science missions by validating these technologies on deep space and Earth-orbiting technology validation missions. The process by which technologies are chosen for validation on NMP flights is complex, because many factors have to be considered. This paper describes the currently approved NMP flight projects and the processes used to select and validate their associated technologies. In addition, the processes being developed to select and validate technologies for future NMP flight projects and the relationships of these processes to NASA technology and science roadmaps will be described. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Minning, CP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 0 Z9 0 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 583 EP 596 PG 14 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200058 ER PT S AU Ticker, RL McLennan, D AF Ticker, RL McLennan, D GP IEEE IEEE TI NASA's New Millennium Space Technology 5 (ST5) project SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB In August 1999, NASA selected Nanosat Constellation Trailblazer (NCT) as the New Millennium ST5 project. NCT will validate technologies needed for future NASA science missions. NCT will reduce the technology risk of producing and operating constellations of small (similar to 10 kg, 10 W total power) satellites. This technology mission will develop, deploy and operate 3 full function 20-Kg class spacecraft. NCT will provide approximately an order of magnitude reduction in spacecraft mass and power. Key issues are the ability to reliably build small spacecraft, deployment, suitability for obtaining research quality measurements, coordination, and control of large numbers of low power satellites, and minimization of cost for both launch and operations. This project is capped at $29M with launch in 2003. This paper summarizes the formal technical study conducted by NASA Goddard Space Flight Center. It describes the mission and technologies, and assesses STS's impact on future NASA science missions. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ticker, RL (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 730, Greenbelt, MD 20771 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 609 EP 617 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200060 ER PT S AU Buehler, MG Cheng, LJ Martin, DP Gompf, RH Calle, CI Bayliss, JA Rauwerdink, JL AF Buehler, MG Cheng, LJ Martin, DP Gompf, RH Calle, CI Bayliss, JA Rauwerdink, JL GP IEEE IEEE TI From concept to flight delivery in eighteen months: The MECA/electrometer case study SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB The rapid development of space instrumentation is increasingly important in this faster, better, cheaper era. This paper discusses the development of the MECA/Electrometer. It used a number of innovations including (a) rapid design of three prototypes, (b) fabrication of 20 units, (c) testing by three institutions, and (d) testing over a wide range of temperature, pressures, atmospheres, and vibration conditions in an eighteen month period. C1 CALTECH, Jet Prop Lab, Microdevices Lab, Pasadena, CA 91109 USA. RP Buehler, MG (reprint author), CALTECH, Jet Prop Lab, Microdevices Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 619 EP 627 PG 9 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200061 ER PT S AU Kortenkamp, D Keirn-Schreckenghost, D Bonasso, RP AF Kortenkamp, D Keirn-Schreckenghost, D Bonasso, RP GP IEEE IEEE TI Adjustable control autonomy for manned space flight SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Autonomous control systems will pray a larger and larger role in manned space flight. These autonomous control systems will make the crew more independent of ground support, thus reducing operation costs. However, for autonomous control systems to be effective, they must allow for insight by crew members and they must also allow crew members to work jointly with and even intervene in autonomous activities. We call this adjustable autonomy. In this paper we present the basic principles of adjustable autonomy and describe three NASA projects in which adjustable autonomy was explored. Conclusions are drawn from these projects. C1 NASA, Lyndon B Johnson Space Ctr ER2, Houston, TX 77058 USA. RP Kortenkamp, D (reprint author), NASA, Lyndon B Johnson Space Ctr ER2, Houston, TX 77058 USA. NR 10 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 629 EP 640 PG 12 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200062 ER PT S AU Engelhardt, B Chien, S Mutz, D AF Engelhardt, B Chien, S Mutz, D GP IEEE IEEE TI Hypothesis generation strategies for adaptive problem solving SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Proposed missions to explore comets and moons will encounter environments that are hostile and unpredictable. Any successful explorer must be able to adapt to a wide range of possible operating conditions in order to survive. The traditional approach of constructing special-purpose control methods would require a information about the environment, which is not available a priori for these missions. An alternate approach is to utilize a general control approach with significant capability to adapt its behavior, a so called adaptive problem-solving methodology. Using adaptive problem-solving. a spacecraft can use reinforcement learning to adapt an environment-specific search strategy given the craft's general problem solver with a flexible control architecture. The resulting methods would enable the spacecraft increase its performance with respect to probability of survival and mission goals. We discuss an application of this approach to learn control strategies in planning and scheduling for three space mission models: Space Technologies 4, a Mars Rover, and Earth Observer One. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Engelhardt, B (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 641 EP 648 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200063 ER PT S AU Rajan, K Shirley, M Taylor, W Kanefsky, B AF Rajan, K Shirley, M Taylor, W Kanefsky, B GP IEEE IEEE TI Ground tools for autonomy in the 21st century SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB Ground tools for unmanned spacecraft are changing rapidly driven by twin innovations: advanced autonomy and ubiquitous networking. Critical issues are the delegation of low-level decision-making to software, the transparency and accountability of that software, mixed-initiative control, i.e., the ability of controllers to adjust portions of the software's activity without disturbing other portions, and the makeup and geographic distribution of the flight control team. These innovations will enable ground controllers to manage space-based resources much more efficiently and, in the case of science missions, give principal investigators an unprecedented level of direct control. This paper explores these ideas by describing the ground tools for the Remote Agent experiment aboard the Deep Space 1 spacecraft in May of 1999. The experiment demonstrated autonomous control capabilities including goal-oriented commanding, on-board planning, robust plan execution and model-based fault protection. We then speculate on the effect of these technologies on the future of spacecraft ground control. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Rajan, K (reprint author), NASA, Ames Res Ctr, MS 269-2, Moffett Field, CA 94035 USA. NR 15 TC 0 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 649 EP 659 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200064 ER PT S AU Johnson, AE Cheng, Y Matthies, LH AF Johnson, AE Cheng, Y Matthies, LH GP IEEE IEEE TI Machine vision for autonomous small body navigation SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc ID COMPUTER AB This paper describes machine vision algorithms that enable precision guidance and hazard avoidance during small body exploration through onboard visual feature tracking and landmark recognition. These algorithms provide estimates of spacecraft relative motion and absolute position used to guide the spacecraft during autonomous landing and exploration. They also enable hazard avoidance by providing estimates of 3-D surface topography through processing of monocular image streams. This form of onboard autonomy is a critical enabling technology for multiple future missions including Comet Nucleus Sample Return, Large Asteroid Sample Return, Titan Organics Explorer and Europa Lander and Mars lander missions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnson, AE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 125-209, Pasadena, CA 91109 USA. NR 13 TC 7 Z9 7 U1 0 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 661 EP 671 PG 11 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200065 ER PT S AU Gat, E AF Gat, E GP IEEE IEEE TI Hard-real-time resource management for autonomous spacecraft SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc AB This paper describes tickets, a computational mechanism for hard-real-time autonomous resource management. Autonomous spacecraft control can be considered abstractly as a computational process whose outputs are spacecraft commands. In order to make the engineering of such systems tractable, these computations are usually organized as multiple parallel threads of control. It is sometimes necessary, particularly in emergency situations, for one thread of control not only to issue certain commands, but to actively prevent the issuing of other commands by other threads of control. Tickets are software objects that act as intermediaries between control processes and low-level commands. In order to gain access to a low-level command a control process must be in posession of a valid ticket for that command. Tickets can be invalidated in constant time. This allows hard-real-time guarantees of performance for denying access to a particular low-level command or set of commands. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gat, E (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 673 EP 677 PG 5 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200066 ER PT S AU Huntsberger, T Aghazarian, H Baumgartner, E Schenker, PS AF Huntsberger, T Aghazarian, H Baumgartner, E Schenker, PS GP IEEE IEEE TI Behavior-based control systems for planetary autonomous robot outposts SO 2000 IEEE AEROSPACE CONFERENCE PROCEEDINGS, VOL 7 SE IEEE AEROSPACE CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE Aerospace Conference CY MAR 18-25, 2000 CL BIG SKY, MT SP IEEE, Aerosp & Electr Syst Soc DE robot outpost; behavior-based control; multi-robot systems ID MOBILE ROBOT; ACTION SELECTION; ROVER CONTROL; NAVIGATION AB Current NASA studies are examining opportunities for the deployment of robot colonies or outposts on planetary surfaces within the solar system in the first few decades of the 21st century. This paper presents the results of some ongoing work in the Planetary Robotics Laboratory at JPL in the area of behavior-based control for cooperative multi-robot systems for a planetary robot outpost. We have recently developed a behavior-based system called BISMARC (Biologically Inspired System for Map-based Autonomous Rover Control) that uses a free flow hierarchy for its action selection mechanism. We report the results of numerous simulation studies of complicated multiple rover missions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Huntsberger, T (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 25 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1095-323X BN 0-7803-5846-5 J9 AEROSP CONF PROC PY 2000 BP 679 EP 686 PG 8 WC Engineering, Aerospace SC Engineering GA BQ98L UT WOS:000165246200067 ER PT B AU Zawadzki, M Huang, J AF Zawadzki, M Huang, J GP IEEE IEEE IEEE TI Integrated RF antenna and solar array for spacecraft application SO 2000 IEEE INTERNATIONAL CONFERENCE ON PHASED ARRAY SYSTEMS AND TECHNOLOGY, PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE International Conference on Phased Array Systems and Technology CY MAY 21-25, 2000 CL DANA POINT, CA SP IEEE, Antennas & Propagat Soc, IEEE, Microwave Theory & Techniques Soc, IEEE, Aerosp & Electr Syst Soc, IEEE, Commun Soc C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Zawadzki, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 2 TC 22 Z9 22 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6345-0 PY 2000 BP 239 EP 242 DI 10.1109/PAST.2000.858948 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BQ72V UT WOS:000089281900049 ER PT B AU Pogorzelski, RJ Scaramastra, RP Huang, J Beckon, RJ Petree, SM Chavez, C AF Pogorzelski, RJ Scaramastra, RP Huang, J Beckon, RJ Petree, SM Chavez, C GP IEEE IEEE IEEE TI An agile beam transmit array using coupled oscillator phase control SO 2000 IEEE INTERNATIONAL CONFERENCE ON PHASED ARRAY SYSTEMS AND TECHNOLOGY, PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE International Conference on Phased Array Systems and Technology CY MAY 21-25, 2000 CL DANA POINT, CA SP IEEE, Antennas & Propagat Soc, IEEE, Microwave Theory & Techniques Soc, IEEE, Aerosp & Electr Syst Soc, IEEE, Commun Soc C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Pogorzelski, RJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6345-0 PY 2000 BP 267 EP 270 DI 10.1109/PAST.2000.858954 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BQ72V UT WOS:000089281900055 ER PT B AU Maleki, L Yao, S Huang, SH Ji, Y Ilchenko, V Tu, M AF Maleki, L Yao, S Huang, SH Ji, Y Ilchenko, V Tu, M GP IEEE IEEE IEEE TI Recent advances in opto-electronic signal generation SO 2000 IEEE INTERNATIONAL CONFERENCE ON PHASED ARRAY SYSTEMS AND TECHNOLOGY, PROCEEDINGS LA English DT Proceedings Paper CT 2000 IEEE International Conference on Phased Array Systems and Technology CY MAY 21-25, 2000 CL DANA POINT, CA SP IEEE, Antennas & Propagat Soc, IEEE, Microwave Theory & Techniques Soc, IEEE, Aerosp & Electr Syst Soc, IEEE, Commun Soc ID OPTOELECTRONIC MICROWAVE-OSCILLATOR; WHISPERING-GALLERY MODES; Q MICROSPHERE CAVITY C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Maleki, L (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 0 Z9 0 U1 2 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6345-0 PY 2000 BP 361 EP 365 DI 10.1109/PAST.2000.858975 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA BQ72V UT WOS:000089281900076 ER PT B AU Keymeulen, D Stoica, A Zebulum, R Jin, YL Duong, V AF Keymeulen, D Stoica, A Zebulum, R Jin, YL Duong, V GP IEEE IEEE TI Fault-tolerant approaches based on evolvable hardware and using a reconfigurable electronic devices SO 2000 IEEE INTERNATIONAL INTEGRATED RELIABILITY WORKSHOP FINAL REPORT LA English DT Proceedings Paper CT IEEE International Integrated Reliability Workshop CY OCT 23-26, 2000 CL LAKE TAHOE, CA SP IEEE Electr Devices Soc, IEEE Reliabil Soc AB The paper presents and compares two approaches to design fault-tolerant evolvable hardware: one based on the fitness definition and the other based an the population statistics. The fitness approach defines, in an explicit way, the faults that the component may encounter during its life time and evaluates the average behavior of the individuals. The population approach uses the implicit information of the population statistics accumulated by the genetic algorithm over many generations. The paper presents experiments done using both approaches on a fine-grained CMOS Field Programmable Transistor Array (FPTA) architecture for the synthesis of a fault-tolerant XNOR digital circuit. Experiments show that the evolutionary algorithm is able to find a fault-tolerant design for the XNOR function that can recover functionality when lost due to not a-priori known faults, by finding new circuits configurations that circumvent the faults. Our preliminary experiments show that the population approach designs a fault-tolerant circuit with a better performance and in less computation than the fitness based approach. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM didier.keymeulen@jpl.nasa.gov NR 27 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6392-2 PY 2000 BP 32 EP 39 DI 10.1109/IRWS.2000.911896 PG 8 WC Engineering, Electrical & Electronic; Physics, Condensed Matter SC Engineering; Physics GA BR68X UT WOS:000167160500007 ER PT B AU Perez, R AF Perez, R GP IEEE IEEE TI Proper design of grounding for SMPS converters SO 2000 IEEE INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY, VOLS 1 AND 2, SYMPOSIUM RECORD LA English DT Proceedings Paper CT International Symposium on Electromagnetic Compatibility CY AUG 21-25, 2000 CL WASHINGTON, D.C. SP IEEE, EMC Soc AB Converters that are used in Switching Mode Power Supply (SMPS) are usually well designed internally so as to maximize efficiency and minimize output noise. However, deficiencies in the distribution of power and grounding within the PCB where the SMPS converters will be located can negate many of the advantages provided by these converters. It is shown that inductive and capacitive effects in the way SMPS converters are used in a PCB are one of the major causes of high conductive emission in PCBs. Furthermore, it is shown that changes in grounding layouts can affect these inductive and capacitive effects. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Perez, R (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5678-0 PY 2000 BP 465 EP 470 PG 6 WC Engineering, Electrical & Electronic SC Engineering GA BR58P UT WOS:000166855100087 ER PT B AU Perez, R AF Perez, R GP IEEE IEEE TI Power conversion techniques for portable EMI sensitive applications SO 2000 IEEE INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY, VOLS 1 AND 2, SYMPOSIUM RECORD LA English DT Proceedings Paper CT International Symposium on Electromagnetic Compatibility CY AUG 21-25, 2000 CL WASHINGTON, D.C. SP IEEE, EMC Soc AB In circuit applications that demand low noise, such as in many portable wireless devices, there is a need to optimize circuit design in power converter circuits. The path to low noise performance does not necessarily require exotic circuit techniques or the latest IC features. Conventional low noise power supply techniques are "tweaked" to improve the performance of dc/dc conversion circuits. A series of improved circuit designs are outlined such as redesigns in push-pull converters, the use of negative railing, the usage of charge pumps (also known as inductorless design), single resistance-capacitance filter, and PCB ground layout. The design techniques are explained and sample circuits are shown. Noise measurements of such re-designed circuits are performed with the improved results explained. Some final attention is paid to pitfalls occurring from using digital layout design hardware in the use of mostly analog layout methods in power conversion circuits. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Perez, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 3 TC 0 Z9 0 U1 1 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5678-0 PY 2000 BP 487 EP 491 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA BR58P UT WOS:000166855100091 ER PT B AU Perez, R AF Perez, R GP IEEE IEEE TI A comparative assessment between linear and switching power supplies in portable electronic devices SO 2000 IEEE INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY, VOLS 1 AND 2, SYMPOSIUM RECORD LA English DT Proceedings Paper CT International Symposium on Electromagnetic Compatibility CY AUG 21-25, 2000 CL WASHINGTON, D.C. SP IEEE, EMC Soc AB The choice between linear and switching power supplies at the board level is sometimes clear cut. However, as the current demands rises and operating voltages sink, considerations must be paid to such factors as power wastage, filtering needs, available board space, and economics. A comparative assessment is made between linear and switching power supplies which should guide the power supply engineer in making intelligent choices as to which option to follow. Design techniques which account for the usage of both linear and switching element in a single board design are also addressed and which may be of future interest to power supply designers. C1 CALTECH, Jet Propuls Lab, Pasadena, CA 91125 USA. RP Perez, R (reprint author), CALTECH, Jet Propuls Lab, Pasadena, CA 91125 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5678-0 PY 2000 BP 839 EP 843 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA BR58P UT WOS:000166855100153 ER PT B AU Divsalar, D Dolinar, S Pollara, F AF Divsalar, D Dolinar, S Pollara, F GP IEEE IEEE TI Serial turbo trellis coded modulation with rate-1 inner code SO 2000 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, PROCEEDINGS LA English DT Proceedings Paper CT IEEE International Symposium on Information Theory CY JUN 24-30, 2000 CL SORRENTO, ITALY SP IEEE, Informat Theory Soc AB We develop new, low-complexity turbo codes suitable for bandwidth and power limited systems. These codes are constructed as an extension of Repeat-Accumulate codes to high-level modulations. Two design criteria are proposed, based on maximum-likelihood decoding and on Gaussian density evolution in iterative decoding. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Divsalar, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5858-9 PY 2000 BP 194 EP 194 DI 10.1109/ISIT.2000.866492 PG 1 WC Computer Science, Information Systems; Computer Science, Theory & Methods SC Computer Science GA BS01R UT WOS:000168322900190 ER PT B AU Divsalar, D Biglieri, E AF Divsalar, D Biglieri, E GP IEEE IEEE TI Upper bounds to error probabilities of coded systems beyond the cutoff rate SO 2000 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, PROCEEDINGS LA English DT Proceedings Paper CT IEEE International Symposium on Information Theory CY JUN 24-30, 2000 CL SORRENTO, ITALY SP IEEE, Informat Theory Soc AB New upper bounds to error probabilities of coded systems such as turbo codes on the additive white Gaussian noise and fading channels were obtained. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Divsalar, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. RI Biglieri, Ezio/A-2246-2012 OI Biglieri, Ezio/0000-0002-8867-2455 NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5858-9 PY 2000 BP 288 EP 288 DI 10.1109/ISIT.2000.866586 PG 1 WC Computer Science, Information Systems; Computer Science, Theory & Methods SC Computer Science GA BS01R UT WOS:000168322900284 ER PT B AU Dolinar, S Divsalar, D Hamkins, J Pollara, F AF Dolinar, S Divsalar, D Hamkins, J Pollara, F GP IEEE IEEE TI Capacity of PPM on Gaussian and Webb channels SO 2000 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, PROCEEDINGS LA English DT Proceedings Paper CT IEEE International Symposium on Information Theory CY JUN 24-30, 2000 CL SORRENTO, ITALY SP IEEE, Informat Theory Soc AB We compare the capacities of M-ary pulse position modulation (PPM) on Gaussian and Webb channels, which are often used to model optical channels with avalanche photodiode (APD) detectors. Both types of channels exhibit the same brickwall thresholds on minimum signal-to-noise ratio per information bit (bit-SNR) for different values of M. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Dolinar, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5858-9 PY 2000 BP 410 EP 410 DI 10.1109/ISIT.2000.866708 PG 1 WC Computer Science, Information Systems; Computer Science, Theory & Methods SC Computer Science GA BS01R UT WOS:000168322900406 ER PT B AU Kiely, A Dolinar, S Klimesh, M Matache, A AF Kiely, A Dolinar, S Klimesh, M Matache, A GP IEEE IEEE TI Error containment in compressed data using sync markers SO 2000 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, PROCEEDINGS LA English DT Proceedings Paper CT IEEE International Symposium on Information Theory CY JUN 24-30, 2000 CL SORRENTO, ITALY SP IEEE, Informat Theory Soc AB We examine a specific strategy of using sync markers for error containment in compressed data, using a model that separates the data compression and error containment stages. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kiely, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 238-420, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5858-9 PY 2000 BP 428 EP 428 DI 10.1109/ISIT.2000.866726 PG 1 WC Computer Science, Information Systems; Computer Science, Theory & Methods SC Computer Science GA BS01R UT WOS:000168322900423 ER PT B AU Divsalar, D Dolinar, S Jin, H McEliece, R AF Divsalar, D Dolinar, S Jin, H McEliece, R GP IEEE IEEE TI AWGN coding theorems from ensemble weight enumerators SO 2000 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, PROCEEDINGS LA English DT Proceedings Paper CT IEEE International Symposium on Information Theory CY JUN 24-30, 2000 CL SORRENTO, ITALY SP IEEE, Informat Theory Soc AB In this paper we develop AWGN coding theorems for ensembles of codes for which we can calculate, or at least closely estimate, the ensemble weight enumerator. As a rule, for such an ensemble we can find a threshold c such that if E-b/N-0 > c, then the ensemble maximum-likelihood error probability approaches zero. This threshold is always better, and usually much better, than can be obtained from the union bound. The role of low-weight code words is key. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Divsalar, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5858-9 PY 2000 BP 459 EP 459 DI 10.1109/ISIT.2000.866757 PG 1 WC Computer Science, Information Systems; Computer Science, Theory & Methods SC Computer Science GA BS01R UT WOS:000168322900454 ER PT S AU Romanofsky, R Bernhard, J Washington, G VanKeuls, F Miranda, F Cannedy, C AF Romanofsky, R Bernhard, J Washington, G VanKeuls, F Miranda, F Cannedy, C BE Perkins, T TI A K-band linear phased array antenna based on Ba0.60Sr0.40TiO3 thin film phase shifters SO 2000 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-3 SE IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST LA English DT Proceedings Paper CT IEEE MTT-S International Microwave Symposium (IMS2000) CY JUN 11-16, 2000 CL BOSTON, MA SP IEEE, MTT S AB This paper summarizes the development of a 23.675 GHz linear 16-element scanning phased array antenna based on thin ferroelectric film coupled microstripline phase shifters and microstrip patch radiators. C1 NASA, Glenn Res Ctr, Cleveland, OH USA. RP Romanofsky, R (reprint author), NASA, Glenn Res Ctr, Cleveland, OH USA. NR 6 TC 3 Z9 5 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 0149-645X BN 0-7803-5687-X J9 IEEE MTT-S PY 2000 BP 1351 EP 1354 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA BR55W UT WOS:000166811000316 ER PT S AU Ponchak, GE Tentzeris, E AF Ponchak, GE Tentzeris, E BE Perkins, T TI Development of finite ground coplanar (FGC) waveguide 90 degree crossover junctions with low coupling SO 2000 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-3 SE IEEE MTT-S International Microwave Symposium LA English DT Proceedings Paper CT IEEE MTT-S International Microwave Symposium (IMS2000) CY JUN 11-16, 2000 CL BOSTON, MA SP IEEE, MTT S AB Microwave and millimeter-wave integrated circuits and RF distribution networks often require two transmission lines to cross over each other. In this paper, experimental measurements and 3D-Finite Difference Time Domain (FDTD) analysis are used to characterize Coplanar Waveguide (CPW) and Finite Ground coplanar (FGC) waveguide crossover junctions for the first time. It is shown that FGC crossover junctions have approximately 15 dB lower coupling than CPW crossover junctions with no degradation in return and insertion loss. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS 54-5, Cleveland, OH 44135 USA. EM george.ponchak@grc.nasa.gov; etentze@ece.gatech.edu NR 7 TC 13 Z9 13 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 0149-645X BN 0-7803-5687-X J9 IEEE MTT S INT MICR PY 2000 BP 1891 EP 1894 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA BR55W UT WOS:000166811000443 ER PT B AU Scheick, LZ Swift, GM Guertin, SM AF Scheick, LZ Swift, GM Guertin, SM GP IEEE IEEE TI SEU evaluation of SRAM memories for space applications. SO 2000 IEEE RADIATION EFFECTS DATA WORKSHOP - WORKSHOP RECORD LA English DT Proceedings Paper CT IEEE Radiation Effects Data Workshop (REDW) held in Conjunction with the IEEE Nuclear and Space Radiation Effects Conference (NSREC 2000) CY JUL 24-28, 2000 CL RENO, NV SP IEEE, Nucl & Plasma Sci Soc, IEEE Inc ID CMOS; TECHNOLOGY AB SEU cross-sections were obtained for three different SRAM memories. The 1 Mbit White Electronics WMS128k8, the 256 kbit Austin MT5C2564 and the 256 kbit Austin MT5C2568 SRAMs were tested. The SEU thresholds, respectively were 1 MeV cm(2)/mg, 1.4 MeV cm(2)/mg, and 1.8 MeV cm(2)/mg, SEL thresholds were also obtained. These were 37 MeV cm(2)/mg, 37 MeV cm(2)/mg and 59 MeV cm(2)/mg, respectively. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Scheick, LZ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6474-0 PY 2000 BP 61 EP 63 DI 10.1109/REDW.2000.896270 PG 3 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA BR45A UT WOS:000166444800011 ER PT B AU McClure, SS Gorelick, JL Pease, R Johnston, AH AF McClure, SS Gorelick, JL Pease, R Johnston, AH GP IEEE IEEE TI Dose rate and bias dependency of total dose sensitivity of low dropout voltage regulators SO 2000 IEEE RADIATION EFFECTS DATA WORKSHOP - WORKSHOP RECORD LA English DT Proceedings Paper CT IEEE Radiation Effects Data Workshop (REDW) held in Conjunction with the IEEE Nuclear and Space Radiation Effects Conference (NSREC 2000) CY JUL 24-28, 2000 CL RENO, NV SP IEEE, Nucl & Plasma Sci Soc, IEEE Inc AB Total dose tests of sis different low dropout voltage regulators show sensitivity to both dose rate and bias during exposure. All devices tested exhibited Enhanced Low Dose Rate Sensitivity (ELDRS) and performed worse for the unbiased irradiation condition. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact to hardness assurance methodology is discussed. C1 Hughes Space & Commun Co, El Segundo, CA 90245 USA. RP McClure, SS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 1 Z9 1 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6474-0 PY 2000 BP 100 EP 105 DI 10.1109/REDW.2000.896278 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA BR45A UT WOS:000166444800019 ER PT B AU LaBel, KA Kniffin, SD Reed, RA Kim, HS Wert, JL Oberg, DL Normand, E Johnston, AH Lum, GK Koga, R Crain, S Schwank, JR Hash, GL Buchner, S Mann, J Simpkins, L D'Ordine, M Marshall, CA O'Bryan, MV Seidleck, CM Nguyen, LX Carts, MA Ladbury, RL Howard, JW AF LaBel, KA Kniffin, SD Reed, RA Kim, HS Wert, JL Oberg, DL Normand, E Johnston, AH Lum, GK Koga, R Crain, S Schwank, JR Hash, GL Buchner, S Mann, J Simpkins, L D'Ordine, M Marshall, CA O'Bryan, MV Seidleck, CM Nguyen, LX Carts, MA Ladbury, RL Howard, JW GP IEEE IEEE TI A compendium of recent optocoupler radiation test data SO 2000 IEEE RADIATION EFFECTS DATA WORKSHOP - WORKSHOP RECORD LA English DT Proceedings Paper CT IEEE Radiation Effects Data Workshop (REDW) held in Conjunction with the IEEE Nuclear and Space Radiation Effects Conference (NSREC 2000) CY JUL 24-28, 2000 CL RENO, NV SP IEEE, Nucl & Plasma Sci Soc, IEEE Inc ID INDUCED TRANSIENTS AB We present a compendium of optocoupler radiation test data including data on neutron, proton and heavy ion Displacement Damage (DD), Single Event Transients (SET) and degradation due to Total Ionizing Dose (TID). Proton data includes ionizing and non-ionizing damage mechanisms. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP LaBel, KA (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 17 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6474-0 PY 2000 BP 123 EP 146 DI 10.1109/REDW.2000.896280 PG 24 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA BR45A UT WOS:000166444800021 ER PT B AU Howard, A Homayoun, S AF Howard, A Homayoun, S GP IEEE IEEE TI Real-time assessment of terrain traversability for autonomous rover navigation SO 2000 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS 2000), VOLS 1-3, PROCEEDINGS LA English DT Proceedings Paper CT IEEE/Robotics-Society-of-Japan International Conference on Intelligent Robots and Systems (IROS 2000) CY OCT 31-NOV 05, 2000 CL KAGAWA UNIV, TAKAMATSU, JAPAN SP IEEE, Ind Electr Soc, IEEE, Robot & Automat Soc, Robot Soc Japan, Soc Instrument & Control Engineers, New Technol Fdn, Kagawa Univ HO KAGAWA UNIV AB This paper presents a novel technique for real-lime measurement of terrain characteristics and incorporation of this information into the navigation strategy of an autonomous mobile robot. The proposed methodology utilizes a fuzzy logic framework for on-board analysis of terrain traversability, and develops a set of fuzzy! navigation rules that guide the rover toward the safest and the mast traversable terrain. In addition, a simple goal-seeking behavior is used to drive the rover from ifs initial position to a user-specified goal position. The overall navigation strategy, consisting of terrain-traverse and goal-seeking behaviors, requires no a priori information about the environment, and uses the on-board traversability analysis to enable the rover to select easy-to-traverse paths to the goal autonomously. The terrain traversability navigation rules are tested and validated with a set of physical rover experiments. These experiments demonstrate the real-time capability of the terrain assessment and fuzzy navigation algorithms. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Howard, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6349-3 PY 2000 BP 58 EP 63 PG 6 WC Engineering, Industrial; Engineering, Electrical & Electronic; Instruments & Instrumentation; Robotics SC Engineering; Instruments & Instrumentation; Robotics GA BR61C UT WOS:000166948600010 ER PT S AU Sherrit, S Bao, X Chang, Z Dolgin, BP Bar-Cohen, Y Pal, D Kroh, J Peterson, T AF Sherrit, S Bao, X Chang, Z Dolgin, BP Bar-Cohen, Y Pal, D Kroh, J Peterson, T BE Schneider, SC Levy, M McAvoy, BR TI Modeling of the ultrasonic/sonic driller/corer: USDC SO 2000 IEEE ULTRASONICS SYMPOSIUM PROCEEDINGS, VOLS 1 AND 2 SE ULTRASONICS SYMPOSIUM LA English DT Proceedings Paper CT IEEE Ultrasonics Symposium CY OCT 22-25, 2000 CL SAN JUAN, PR SP IEEE Ultrason, Ferroelect, & Frequency Control Soc AB Future NASA missions to Mars require sampling techniques for in-situ analysis and/or sample return to Earth. One of the major limitations of sample collection on Mars and other low gravity environments using conventional drilling is the need for high axial force during drilling. In order to address this problem an ultrasonic/sonic drilling/coring (USDC) mechanism based on an ultrasonic horn driven by a piezoelectric stack has been developed. The horn drives a free mass, which resonates, between the horn and drill stem. Tests have shown that this device addresses some of the key challenges to this NASA objective of planetary in-situ analysis or sampling. The USDC is lightweight (450 g), requires low preload (< 5N) and can be driven at low power (5W). The device has been shown to drill various rocks including granite, diorite, basalt and limestone. Although the drill is driven electrically at 20 kHz, a substantial sub-harmonic acoustic component is found that is crucial to drilling performance. Models that explain this low frequency coupling in the horn, free mass, drill stem and rock will be presented. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sherrit, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 1 Z9 1 U1 1 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1051-0117 BN 0-7803-6365-5 J9 ULTRASON PY 2000 BP 691 EP 694 PG 4 WC Acoustics; Engineering, Industrial; Radiology, Nuclear Medicine & Medical Imaging SC Acoustics; Engineering; Radiology, Nuclear Medicine & Medical Imaging GA BT07X UT WOS:000171881300147 ER PT S AU Sherrit, S Bar-Cohen, SPLY Dolgin, BP Tasker, R AF Sherrit, S Bar-Cohen, SPLY Dolgin, BP Tasker, R BE Schneider, SC Levy, M McAvoy, BR TI Analysis of the impedance resonance of piezoelectric stacks SO 2000 IEEE ULTRASONICS SYMPOSIUM PROCEEDINGS, VOLS 1 AND 2 SE ULTRASONICS SYMPOSIUM LA English DT Proceedings Paper CT IEEE Ultrasonics Symposium CY OCT 22-25, 2000 CL SAN JUAN, PR SP IEEE Ultrason, Ferroelect, & Frequency Control Soc ID CONSTANTS AB Inversion techniques to determine the complex material constants from the impedance data of a zero bond-length stack resonator are studied. The impedance equation examined in this paper is based on the derivation by Martin [G.E. Martin, JASA, 36, pp. 1496-1506, 1964]. The asymptotic solutions for the case where the number of layers n is large (n >8) and n small (n less than or equal to2) are presented in terms of the complex material constants of the piezoelectric. When n = 1 or 2, it is shown that the wave speed in the stack is determined by the open circuit elastic constant s(33)(D). In the limit of large n, the wave speed is determined by the short circuit elastic constant S-33(E). Techniques to invert the impedance data to determine complex material constants are presented for all values of n. The error associated with using the impedance equations derived from fully short and fully open electrical boundary conditions is investigated. Since the model is based on material properties rather than circuit constants, it allows for the direct evaluation of specific aging or degradation mechanisms. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sherrit, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 82-105, Pasadena, CA 91109 USA. NR 7 TC 1 Z9 1 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1051-0117 BN 0-7803-6365-5 J9 ULTRASON PY 2000 BP 1037 EP 1040 PG 4 WC Acoustics; Engineering, Industrial; Radiology, Nuclear Medicine & Medical Imaging SC Acoustics; Engineering; Radiology, Nuclear Medicine & Medical Imaging GA BT07X UT WOS:000171881300224 ER PT B AU DeAnna, RG Mitchell, J Zorman, CA Mehregany, M AF DeAnna, RG Mitchell, J Zorman, CA Mehregany, M BE Laudon, M Romanowicz, B TI Finite-element modeling of 3C-SiC membranes SO 2000 INTERNATIONAL CONFERENCE ON MODELING AND SIMULATION OF MICROSYSTEMS, TECHNICAL PROCEEDINGS LA English DT Proceedings Paper CT 3rd International Conference on Modeling and Simulation of Microsystems CY MAR 27-29, 2000 CL San Diego, CA SP DARPA, Coyote Syst, MEMSCAP, SA, Mol Simulat Inc, Microcosm Technologies Inc, IEEE Electron Devices Soc, Motorola, Appl Computat Res Soc, Swiss Fed Inst Technol Lausanne, TIMA CMP Lab, Los Alamos Natl Lab, Int Assoc Math & Comp Modeling DE silicon carbide; MEMS; ANSYS; membrane; FEM ID THERMAL-EXPANSION; STRESSES AB Finite-element modeling (FEM) of 3C-SiC thin-film membranes on Si substrates was used to determine the residual stress and center deflection with applied pressure. The anisotropic, three-dimensional model includes the entire 3C-SiC membrane and Si substrate with appropriate material properties and boundary conditions. Residual stress due to the thermal-expansion-coefficient mismatch between the 3C-SiC film and Si substrate was included in the model. Both before- and after-etching, residual stresses were calculated. In-plane membrane stress and normal deflection with applied pressure were also calculated. FEM results predict a tensile residual stress of 259 MPa in the 3C-SiC membrane before etching. This decreases to 247 MPa after etching the substrate below the membrane. The residual stress experimentally measured on samples made at Case Western Reserve University was 280 MPa on post-etched membranes. This is excellent agreement when an additional 30-40 MPa of residual stress to account for lattice mismatch is added to the FEM results. C1 USA, Res Lab, NASA, Glenn Res Ctr, Cleveland, OH USA. RP DeAnna, RG (reprint author), USA, Res Lab, NASA, Glenn Res Ctr, Cleveland, OH USA. OI Zorman, Christian/0000-0001-9773-9351 NR 6 TC 0 Z9 0 U1 0 U2 0 PU COMPUTATIONAL PUBLICATIONS PI CAMBRIDGE PA PUBISHING OFFICE, 308 ONE KENDALL SQ BLDG 600, CAMBRIDGE, MA 02139 USA BN 0-9666135-7-0 PY 2000 BP 253 EP 256 PG 4 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Condensed Matter SC Engineering; Materials Science; Physics GA BAO05 UT WOS:000223049100064 ER PT B AU Kuhn, JL Dutta, SB Greenhouse, MA Mott, DB AF Kuhn, JL Dutta, SB Greenhouse, MA Mott, DB BE Laudon, M Romanowicz, B TI Simulation of aluminum micro-mirrors for space applications at cryogenic temperatures SO 2000 INTERNATIONAL CONFERENCE ON MODELING AND SIMULATION OF MICROSYSTEMS, TECHNICAL PROCEEDINGS LA English DT Proceedings Paper CT 3rd International Conference on Modeling and Simulation of Microsystems CY MAR 27-29, 2000 CL San Diego, CA SP DARPA, Coyote Syst, MEMSCAP, SA, Mol Simulat Inc, Microcosm Technologies Inc, IEEE Electron Devices Soc, Motorola, Appl Computat Res Soc, Swiss Fed Inst Technol Lausanne, TIMA CMP Lab, Los Alamos Natl Lab, Int Assoc Math & Comp Modeling DE micro-mirrors; simulation; cryogenic; electrostatic; thermal AB Closed form and finite element models are developed to predict the device response of aluminum electrostatic torsion micro-mirrors fabricated on silicon substrate for space applications at operating temperatures of 30K. Initially, closed form expressions for electrostatic pressure and mechanical restoring torque are used to predict the pull-in and release voltages at room temperature. Subsequently, a detailed mechanical finite element model is developed to predict stresses and vertical beam deflection induced by the electrostatic and thermal loads. An incremental and iterative solution method is used in conjunction with the non-linear finite element model and closed form electrostatic equations to solve the coupled electro-thermo-mechanical problem. The simulation results are compared with experimental measurements at room temperature of fabricated micromirror devices. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kuhn, JL (reprint author), NASA, Goddard Space Flight Ctr, Code 542, Greenbelt, MD 20771 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU COMPUTATIONAL PUBLICATIONS PI CAMBRIDGE PA PUBISHING OFFICE, 308 ONE KENDALL SQ BLDG 600, CAMBRIDGE, MA 02139 USA BN 0-9666135-7-0 PY 2000 BP 676 EP 679 PG 4 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Condensed Matter SC Engineering; Materials Science; Physics GA BAO05 UT WOS:000223049100170 ER PT B AU Kayali, S AF Kayali, S GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Reliability considerations for advanced microelectronics SO 2000 PACIFIC RIM INTERNATIONAL SYMPOSIUM ON DEPENDABLE COMPUTING, PROCEEDINGS LA English DT Proceedings Paper CT Pacific Rim International Symposium on Dependable Computing CY DEC 18-20, 2000 CL LOS ANGELES, CA SP IEEE Comp Soc, Tech Comm Fault Tolerant Comp, IFIP WG10 4 Dependable Comp & Fault Tolerance, Univ Calif Los Angeles, Comp Sci Dept, IEICE, Tech Comm Fault Tolerant Syst C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kayali, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 303-200, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-0975-4 PY 2000 BP 99 EP 99 PG 1 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BR48R UT WOS:000166593500014 ER PT B AU Hemminger, E Burkhardt, R AF Hemminger, E Burkhardt, R GP IEST IEST IEST TI Verification of bolt pre-load SO 2000 PROCEEDINGS: INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY LA English DT Proceedings Paper CT 46th Annual Technical Meeting and Exposition of the Institute-of-Environmental-Sciences-and-Technology (ESTECH 2000) CY APR 30-MAY 04, 2000 CL PROVIDENCE, RI SP Inst Environm Sci & Technol AB Bolt pre-load verification is critical for space flight applications due to the large launch loads that must be sustained during lift off. In addition to these large structural loads, which can exceed 10g's, flight payloads are also subjected to significant in-orbit thermal loading due to solar and electronic heating sources. Typical temperature cycles can vary from ambient at launch to very cold space environment temperatures of -60 degrees F. In orbit temperatures also, can vary from -60 to well over 100 degrees F due to solar and electronic heating. For these reasons, bolt pre-load specification is extremely important and must be verified to insure that flight payload structural connections remain tight over projected loading due to mechanical and thermal life cycles. To this end, a bolt pre-load measuring instrument has been developed and successfully used at the Goddard Space Flight Center to verify pre-load application of critical spacecraft bolted connections. This instrument has been successfully used for bolt pre-load verification testing on the Tropical Rain Measuring Mission (TRMM) and the CAPL Flight Experiment. For these projects, specified torque levels were verified by fastener testing as follows: 1. Each fastener type and size was tested in a flight like test setup. 2. A minimum five fasteners (each size) were tested and average measured torque values were then used for flight payload assembly. Typical data from a recently completed Fastener Test Program performed for the Naval Research Center for Space Technology is presented and discussed below. C1 NASA, Goddard Space Flight Ctr, Aerosp Technol Applicat Ctr, Man Tech Int Corp, Greenbelt, MD 20771 USA. RP Hemminger, E (reprint author), NASA, Goddard Space Flight Ctr, Aerosp Technol Applicat Ctr, Man Tech Int Corp, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU INST ENVIRONMENTAL SCIENCES PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 USA BN 1-877862-73-8 PY 2000 BP 195 EP 203 PG 9 WC Environmental Sciences SC Environmental Sciences & Ecology GA BR28L UT WOS:000166022300027 ER PT B AU Chang, KY AF Chang, KY GP IEST IEST IEST TI Deep Space 1 spacecraft vibration qualification testing SO 2000 PROCEEDINGS: INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY LA English DT Proceedings Paper CT 46th Annual Technical Meeting and Exposition of the Institute-of-Environmental-Sciences-and-Technology (ESTECH 2000) CY APR 30-MAY 04, 2000 CL PROVIDENCE, RI SP Inst Environm Sci & Technol AB The environmental qualification program for the Deep Space 1 spacecraft included a force-limited random vibration test in two axes. The Deep Space 1 is NASA's first New Millennium Program deep-space mission involving an asteroid flyby to validate several advanced payload technologies. The spacecraft was successfully launched in October 1998 on a Delta II launch vehicle. The spacecraft vibration test demonstrates design qualification and workmanship verification of the assembled flight spacecraft for the vibration environment encountered during launch. The semi-empirical force limit procedure was used to derive force limits for the test. The results of the test show that the acceleration inputs measured near the feet of a number of spacecraft mounted instruments reached their assembly random vibration test specifications. Also, several major structural elements of the spacecraft reached their flight limit loads during the spacecraft vibration test. Test results, as well as lessons learned, from those tests will be discussed in the paper. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chang, KY (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 157-410, Pasadena, CA 91109 USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU INST ENVIRONMENTAL SCIENCES PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 USA BN 1-877862-73-8 PY 2000 BP 351 EP 356 PG 6 WC Environmental Sciences SC Environmental Sciences & Ecology GA BR28L UT WOS:000166022300047 ER PT B AU Ponchak, GE Margomenos, A Katehi, LPB AF Ponchak, GE Margomenos, A Katehi, LPB BE Fisch, W Ponchak, GE TI Low loss, finite width ground plane, thin film microstrip lines on Si wafers SO 2000 TOPICAL MEETING ON SILICON MONOLITHIC INTEGRATED CIRCUITS IN RF SYSTEMS, DIGEST OF PAPERS LA English DT Proceedings Paper CT 2nd Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems CY APR 26-28, 2000 CL GARMISCH PARTENKI, GERMANY SP IEEE Microwave Theory & Techn Soc, NASA Glenn Res Ctr, Daimler Chrysler AG, Infineon Technologies AG AB Si RFICs on standard, 2 Omega-cm Si wafers require novel transmission lines to reduce the loss caused by the resistive substrate. One such transmission line is commonly called Thin Film used Tor tl Microstrip (TFMS), which is created by microstrip depositing a metallic ground plane, thin insulating polyimide. layers, and the microstrip lines on the Si wafer. In Thus, the electric fields are isolated from the Si wafer. In this paper, it is shown through experimental results that the ground plane of TFMS may be finite width and comparable to the strip width in size while still achieving low loss on 2 Omega-cm Si. Measured effective permittivity shows that the field interaction with the Si wafer is small. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Ponchak, GE (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS 54-5, Cleveland, OH 44135 USA. NR 7 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6255-1 PY 2000 BP 43 EP 47 DI 10.1109/SMIC.2000.844294 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA BQ43Z UT WOS:000088359600011 ER PT B AU Mueller, CH Alterovitz, SA Croke, ET AF Mueller, CH Alterovitz, SA Croke, ET BE Fisch, W Ponchak, GE TI Materials optimization for high power silicon germanium heterostructure bipolar transistors at X-band frequencies SO 2000 TOPICAL MEETING ON SILICON MONOLITHIC INTEGRATED CIRCUITS IN RF SYSTEMS, DIGEST OF PAPERS LA English DT Proceedings Paper CT 2nd Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems CY APR 26-28, 2000 CL GARMISCH PARTENKI, GERMANY SP IEEE Microwave Theory & Techn Soc, NASA Glenn Res Ctr, Daimler Chrysler AG, Infineon Technologies AG ID MOLECULAR-BEAM EPITAXY; RECOMBINATION; MORPHOLOGY AB SiGe base layers with high (>0.15 Ge) can potentially extend the range of high power HBTs to X-band and higher frequencies, but in practice the actual performance of these devices is usually poorer than the anticipated results. Optimization and reproducibility of materials properties is essential for the successful development of these devices, and this paper reports microstructural characterization of high-Ge content films, simulates the performance of an HBT structure, and provides insights into how materials defects impact device performance. High resolution x-ray diffraction indicates that the crystalline quality of SiGe layers is highly degraded with increasing Ge contents, and interfacial relaxation becomes apparent for Ge > 0.15. The SiGe layer thicknesses and Ge contents were measured using both optical ellipsometry and SIMS, and the results were comparable. Simulated data of an HBT transistor shows that minor variations in Ge content alter the cutoff frequencies and gain of the transistors, and base recombination times less that approximate to 5x10(-7) seconds severely impair device performance. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Mueller, CH (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 11 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6255-1 PY 2000 BP 173 EP 176 DI 10.1109/SMIC.2000.844325 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BQ43Z UT WOS:000088359600042 ER PT B AU Ting, DZY Gu, M Cao, JW Chi, XB Schulman, JN AF Ting, DZY Gu, M Cao, JW Chi, XB Schulman, JN GP IEEE TI Three-dimensional quantum transport by supercell method: Numerical acceleration and applications SO 2001 IEEE INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS LA English DT Proceedings Paper CT IEEE 27th International Symposium on Compound Semiconductors CY OCT 02-05, 2000 CL MONTEREY, CA SP IEEE, IEEE Laser & Electro-Opt Soc, EDS ID INTERFACE ROUGHNESS; TUNNELING STRUCTURES; IMPURITIES; QMR AB The open-boundary planar supercell stack method treats three-dimensional quantum transport in mesoscopic tunnel structures in a numerically stable and efficient manner. The method formulates quantum mechanical scattering problems for the supercell geometry as sparse linear systems, which can be solved by iterative methods. Recent improvement in solution algorithm using a seven-diagonal pre-conditioner has resulted in over two orders of magnitude of numerical acceleration, bringing more flexibility in the range of problems we can tackle. We will discuss applications to interface roughness in double barrier resonant tunneling structures and tunneling characteristics of ultra-thin oxides undergoing dielectric breakdown. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ting, DZY (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6258-6 PY 2000 BP 185 EP 190 DI 10.1109/ISCS.2000.947151 PG 6 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Materials Science, Characterization & Testing SC Engineering; Materials Science GA BT16D UT WOS:000172146400032 ER PT B AU Klimeck, G Bowen, C Boykin, TB AF Klimeck, G Bowen, C Boykin, TB GP IEEE TI Transverse momentum dependence of electron and hole tunneling in a full band tight-binding simulation SO 2001 IEEE INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS LA English DT Proceedings Paper CT IEEE 27th International Symposium on Compound Semiconductors CY OCT 02-05, 2000 CL MONTEREY, CA SP IEEE, IEEE Laser & Electro-Opt Soc, EDS ID CURRENT-VOLTAGE CALCULATIONS; SEMICONDUCTOR STRUCTURES; HETEROSTRUCTURES; APPROXIMATION; STATES; DIODES AB Heterointerfaces, applied bias and built-in potentials break the symmetry of the crystalline lattice in a resonant tunneling diode (RTD) which causes a strong interaction of heavy-, light- and split-off hole bands. This interaction leads to hole transport paths which are significantly more complicated than the paths for electrons. Compared to a direct bandgap electron RTD where most of the carriers are transported straight through the structure (zero transverse momentum) it is shown here that in the hole case most of the holes are transported through the structure at an angle (non-zero transverse momentum) for a wide range of bias points. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM gekco@jpl.nasa.gov RI Klimeck, Gerhard/A-1414-2012 OI Klimeck, Gerhard/0000-0001-7128-773X NR 23 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-6258-6 PY 2000 BP 257 EP 262 DI 10.1109/ISCS.2000.947165 PG 6 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Materials Science, Characterization & Testing SC Engineering; Materials Science GA BT16D UT WOS:000172146400044 ER PT S AU Wu, BHH AF Wu, BHH GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI A framework for WWW query processing SO 24TH ANNUAL INTERNATIONAL COMPUTER SOFTWARE AND APPLICATIONS CONFERENCE (COSPSAC 2000) SE PROCEEDINGS - INTERNATIONAL COMPUTER SOFTWARE & APPLICATIONS CONFERENCE LA English DT Proceedings Paper CT 24th Annual International Computer Software and Applications Conference (COMPSAC 2000) CY OCT 25-27, 2000 CL TAIPEI, TAIWAN SP IEEE, Comp Soc, Fash Now Corp, Flowring Technol Corp, Inst Informat Ind, MITAC Synnex Grp, Microelect Technol Inc, Natl Sci Council, Natl Tsing Hua Univ, Puretek Ind Co Ltd, TSMC, Tung Hai Univ, World Peace Ind Co Ltd, Zen Technol Co Ltd AB Query processing is the most common operation in a DBMS. Sophisticated query processing has been mainly targeted at a single enterprise environment providing centralized control over data and metadata. Submitting queries by anonymous users on the web is different in such a way that load balancing or DBMS' accessing control becomes the key issue. This paper provides a solution by introducing a framework for WWW query processing. The success of this framework lies in the utilization of query optimization techniques [1] and the ontological [2] approach. This methodology has proved to be cost effective at the NASA Goddard Space Flight Center Distributed Active Archive Center (GDAAC) [3]. C1 NASA, Goddard Space Flight Ctr, Raytheon, ITSS,GDAAC Eng, Greenbelt, MD 20771 USA. RP Wu, BHH (reprint author), NASA, Goddard Space Flight Ctr, Raytheon, ITSS,GDAAC Eng, Code 902, Greenbelt, MD 20771 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA SN 0730-3157 BN 0-7695-0792-1 J9 P INT COMP SOFTW APP PY 2000 VL 24 BP 187 EP 188 PG 2 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BR15H UT WOS:000165736000032 ER PT S AU Nikora, AP AF Nikora, AP GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Inserting software fault measurement techniques into development efforts SO 24TH ANNUAL INTERNATIONAL COMPUTER SOFTWARE AND APPLICATIONS CONFERENCE (COSPSAC 2000) SE PROCEEDINGS - INTERNATIONAL COMPUTER SOFTWARE & APPLICATIONS CONFERENCE LA English DT Proceedings Paper CT 24th Annual International Computer Software and Applications Conference (COMPSAC 2000) CY OCT 25-27, 2000 CL TAIPEI, TAIWAN SP IEEE, Comp Soc, Fash Now Corp, Flowring Technol Corp, Inst Informat Ind, MITAC Synnex Grp, Microelect Technol Inc, Natl Sci Council, Natl Tsing Hua Univ, Puretek Ind Co Ltd, TSMC, Tung Hai Univ, World Peace Ind Co Ltd, Zen Technol Co Ltd AB Over the past several years, techniques for estimating software fault content based on measurements of a system's structural evolution during its implementation have been developed. Proper application of the techniques will yield a detailed map of the faults that have been inserted into the system. This information can be used by development organizations to better control the number of residual faults in the operational system. There are several issues that must be resolved if these techniques are to be successfully inserted into a development effort. These issues are identified, as are possibilities for their resolution. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Nikora, AP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA SN 0730-3157 BN 0-7695-0792-1 J9 P INT COMP SOFTW APP PY 2000 VL 24 BP 274 EP 275 DI 10.1109/CMPSAC.2000.884731 PG 2 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BR15H UT WOS:000165736000047 ER PT B AU Ferreira, RN Suarez, M Bacmeister, J AF Ferreira, RN Suarez, M Bacmeister, J GP AMS AMS TI Role of easterly waves in the maintenance of the African easterly jet SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, NSIPP Climatae & Radiat Branch, USRA, Greenbelt, MD 20771 USA. RP Ferreira, RN (reprint author), NASA, Goddard Space Flight Ctr, NSIPP Climatae & Radiat Branch, USRA, Code 913, Greenbelt, MD 20771 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 13 EP 14 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700007 ER PT B AU Pu, ZX Braun, SA AF Pu, ZX Braun, SA GP AMS AMS TI Evaluation of bogus vortex techniques using a four-dimensional variational data assimilation system SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc ID SIMULATION; MODEL C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Pu, ZX (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 118 EP 119 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700059 ER PT B AU Rickenbach, TM Ferreira, RN Halverson, JB Cifelli, R AF Rickenbach, TM Ferreira, RN Halverson, JB Cifelli, R GP AMS AMS TI Evolution of mesoscale convective systems in contrasting large scale regimes from radar and infrared satellite data during the TRMM-LBA field campaign in Rondonia, Brazil SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Mesoscale Branch, Greenbelt, MD 20771 USA. RP Rickenbach, TM (reprint author), NASA, Goddard Space Flight Ctr, Mesoscale Branch, Code 912, Greenbelt, MD 20771 USA. NR 3 TC 1 Z9 1 U1 0 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 139 EP 140 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700070 ER PT B AU Wolff, DB AF Wolff, DB GP AMS AMS TI Vertical reflectivity profiles and lightning characteristics of landfalling hurricanes & tropical storms SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc ID RADAR C1 NASA, Goddard Space Flight Ctr, Space Syst & Applicat Inc, Greenbelt, MD 20771 USA. RP Wolff, DB (reprint author), NASA, Goddard Space Flight Ctr, Space Syst & Applicat Inc, Code 661, Greenbelt, MD 20771 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 296 EP 297 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700149 ER PT B AU Schauer, AG Schmidlin, FJ AF Schauer, AG Schmidlin, FJ GP AMS AMS TI The modification of the water vapor profile during the passage of a tropical system SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, Wallops Flight Facil, GSFC, Wallops Isl, VA 23336 USA. RP Schauer, AG (reprint author), NASA, Wallops Flight Facil, GSFC, Bldg N-159, Wallops Isl, VA 23336 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 352 EP 353 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700177 ER PT B AU Rothermel, J Cutten, DR Howell, JN Darby, LS Hardesty, RM Tratt, DM Menzies, RT AF Rothermel, J Cutten, DR Howell, JN Darby, LS Hardesty, RM Tratt, DM Menzies, RT GP AMS AMS TI Hurricane wind field measurements with scanning airborne Doppler lidar during Camex-3 SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, Global Hydrol & Climate Ctr, MSFC, Huntsville, AL 35806 USA. RP Rothermel, J (reprint author), NASA, Global Hydrol & Climate Ctr, MSFC, 977 Explorer Blvd, Huntsville, AL 35806 USA. NR 3 TC 1 Z9 1 U1 1 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 354 EP 355 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700178 ER PT B AU Heymsfield, GM Halverson, J Tian, L Geerts, B AF Heymsfield, GM Halverson, J Tian, L Geerts, B GP AMS AMS TI Hurricane Bonnie landfalling observed from ER-2 Doppler radar on 26 August 1998 during Camex-3 SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Heymsfield, GM (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 356 EP 357 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700179 ER PT B AU Guillory, AR Jedlovec, GJ Hood, RE Atkinson, RJ LaFontaine, FJ AF Guillory, AR Jedlovec, GJ Hood, RE Atkinson, RJ LaFontaine, FJ GP AMS AMS TI Entrainment of upper level dry air into Hurricane Earl SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. RP Guillory, AR (reprint author), NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Mail Stop SD60, Huntsville, AL 35812 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 358 EP 359 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700180 ER PT B AU Braun, SA Simpson, J Tao, WK AF Braun, SA Simpson, J Tao, WK GP AMS AMS TI Kinematic and thermodynamic structures of Hurricane Bob (1991) determined from a 1.3-km-resolution numerical simulation SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Braun, SA (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. NR 3 TC 3 Z9 3 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 376 EP 377 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700189 ER PT B AU Chao, WC Chen, B AF Chao, WC Chen, B GP AMS AMS TI On the origin of monsoon SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chao, WC (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 433 EP 434 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700218 ER PT B AU Olson, WS Hong, Y Yang, S Kummerow, CD Tao, WK AF Olson, WS Hong, Y Yang, S Kummerow, CD Tao, WK GP AMS AMS TI Large-scale precipitation and latent heating distributions in the tropics derived from satellite-borne passive and active microwave sensors SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc ID FREQUENCY INTRASEASONAL OSCILLATIONS; TOGA COARE; CONVECTIVE SYSTEMS; CLOUD CLUSTERS; WAVE-CISK; RAINFALL; ATMOSPHERE; PROFILES; BUDGET; ORIGIN C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Olson, WS (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. NR 19 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 435 EP 436 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700219 ER PT B AU Sui, CH Lau, KM Li, X Ho, CH AF Sui, CH Lau, KM Li, X Ho, CH GP AMS AMS TI Radiative-convective processes in regulating tropical ocean-atmosphere SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sui, CH (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. RI Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 506 EP 507 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700255 ER PT B AU Rodgers, E Weinman, J Pierce, H Olson, W AF Rodgers, E Weinman, J Pierce, H Olson, W GP AMS AMS TI 16B-7 tropical cyclone lightning distribution and its relationship to convection and intensity change SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc ID HURRICANES C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Rodgers, E (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. NR 9 TC 6 Z9 6 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 537 EP 541 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700270 ER PT B AU LaFontaine, FJ Hood, RE Guillory, AR AF LaFontaine, FJ Hood, RE Guillory, AR GP AMS AMS TI Tropical microwave brightness temperature data from AMPR SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 Raytheon ITSS, Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35806 USA. RP LaFontaine, FJ (reprint author), Raytheon ITSS, Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35806 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 594 EP 595 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700297 ER PT B AU Hood, RE Smith, E Guillory, AR LaFontaine, FJ AF Hood, RE Smith, E Guillory, AR LaFontaine, FJ GP AMS AMS TI Passive microwave observations of hurricanes during CAMEX-3 SO 24TH CONFERENCE ON HURRICANES AND TROPICAL METEOROLOGY/10TH CONFERENCE ON INTERACTION OF THE SEA AND ATMOSPHERE LA English DT Proceedings Paper CT 24th Conference on Hurricanes and Tropical Meteorology/10th Conference on Interaction of the Sea and Atmosphere CY MAY 29-JUN 02, 2000 CL FT LAUDERDALE, FL SP Amer Meteorol Soc C1 NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35806 USA. RP Hood, RE (reprint author), NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35806 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2000 BP 596 EP 597 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BY37V UT WOS:000189132700298 ER PT S AU Baring, MG AF Baring, MG BE Dingus, BL Kieda, DB Salamon, MH TI Cosmic ray origin, acceleration and propagation SO 26TH INTERNATIONAL COSMIC RAY CONFERENCE SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 26th International Cosmic Ray Conference (ICRC) CY AUG 17-25, 1999 CL SALT LAKE CITY, UT SP IUPAP, US DOE, US Natl Sci Fdn, NASA, Utah High Energy Astrophys Inst, Univ Utah, Sun Microsyst, Hamamatsu Inc, Photonis Inc, W IE NE R Plein & Baus GmbH ID SHOCK ACCELERATION; ENERGETIC PARTICLES; SUPERNOVA-REMNANTS; RADIO AB This paper summarizes highlights of the OG3.1, 3.2 and 3.3 sessions of the XXVIth International Cosmic Ray Conference in Salt Lake City, which were devoted to issues of origin/composition, acceleration and propagation. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Baring, MG (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 31 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 1-56396-939-4 J9 AIP CONF PROC PY 2000 VL 516 BP 153 EP 168 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BQ50L UT WOS:000088536700009 ER PT S AU Reames, DV AF Reames, DV BE Dingus, BL Kieda, DB Salamon, MH TI Particle acceleration by CME-driven shock waves SO 26TH INTERNATIONAL COSMIC RAY CONFERENCE SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 26th International Cosmic Ray Conference (ICRC) CY AUG 17-25, 1999 CL SALT LAKE CITY, UT SP IUPAP, US DOE, US Natl Sci Fdn, NASA, Utah High Energy Astrophys Inst, Univ Utah, Sun Microsyst, Hamamatsu Inc, Photonis Inc, W IE NE R Plein & Baus GmbH ID SOLAR ENERGETIC PARTICLES; INTERPLANETARY TRAVELING SHOCKS; CORONAL MASS EJECTIONS; ION-ACCELERATION; HEAVY-IONS; FLARES; EVENTS; SPECTRA; CHARGE; ABUNDANCES AB In the largest solar energetic particle (SEP) events, acceleration occurs at shock waves driven out from the Sun by coronal mass ejections (CMEs). Peak particle intensities are a strong function of CME speed, although the intensities, spectra, and angular distributions of particles escaping the shock are highly modified by scattering on Alfven waves produced by the streaming particles themselves. Element abundances vary in complex wars because ions with different values of Q/A resonate with different parts of the wave spectrum, which varies with space and time. Just recently, we have begun to model these systematic variations theoretically and to explore other consequences of proton-generated waves. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Reames, DV (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 51 TC 26 Z9 26 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 1-56396-939-4 J9 AIP CONF PROC PY 2000 VL 516 BP 289 EP 300 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BQ50L UT WOS:000088536700018 ER PT S AU Wiedenbeck, ME AF Wiedenbeck, ME BE Dingus, BL Kieda, DB Salamon, MH TI Cosmic-Ray Isotopic Composition results from the ACE mission SO 26TH INTERNATIONAL COSMIC RAY CONFERENCE SE AIP Conference Proceedings LA English DT Proceedings Paper CT 26th International Cosmic Ray Conference (ICRC) CY AUG 17-25, 1999 CL SALT LAKE CITY, UT SP IUPAP, US DOE, US Natl Sci Fdn, NASA, Utah High Energy Astrophys Inst, Univ Utah, Sun Microsyst, Hamamatsu Inc, Photonis Inc, W IE NE R Plein & Baus GmbH ID INTERSTELLAR-MEDIUM; II SUPERNOVAE; NUCLEOSYNTHESIS; EVOLUTION; ELEMENTS; GALAXY; EJECTA; NUCLEI; SOLAR AB The Cosmic Ray Isotope Spectrometer (CRIS) instrument on the Advanced Composition Explorer (ACE) mission has been making high precision measurements of the isotopic and elemental composition of galactic cosmic rays over the past two years. These observations have been used to investigate a range of topics including: 1) the nucleosynthetic processes that produced the cosmic-ray source material, 2) the processes responsible for fractionation of the elements in this material, 3) the time that elapsed between nucleosynthesis and acceleration to high energies, and 4) the confinement time of cosmic rays in the Galaxy. Highlights from CRIS investigations reported to date are summarized. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-327, Pasadena, CA 91109 USA. NR 31 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 1-56396-939-4 J9 AIP CONF PROC PY 2000 VL 516 BP 301 EP 309 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BQ50L UT WOS:000088536700019 ER PT B AU Lowman, PD AF Lowman, PD BE Aanstoos, JV TI Orbital remote sensing of the earth's surface: A review SO 29TH APPLIED IMAGERY PATTERN RECOGNITION WORKSHOP, PROCEEDINGS LA English DT Proceedings Paper CT 29th Applied Imagery Pattern Recognition Workshop CY OCT 16-18, 2000 CL WASHINGTON, D.C. SP IEEE Comp Soc Tech Comm Pattern Anal & Machine Intelligence, Pattern Analy & Machine Intelligence C1 Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. RP Lowman, PD (reprint author), Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-0978-9 PY 2000 BP 11 EP 11 DI 10.1109/AIPRW.2000.953597 PG 1 WC Computer Science, Artificial Intelligence; Remote Sensing; Imaging Science & Photographic Technology; Radiology, Nuclear Medicine & Medical Imaging SC Computer Science; Remote Sensing; Imaging Science & Photographic Technology; Radiology, Nuclear Medicine & Medical Imaging GA BT17G UT WOS:000172147200003 ER PT B AU Smit, M Garegnani, J Bechdol, M Chettri, S AF Smit, M Garegnani, J Bechdol, M Chettri, S BE Aanstoos, JV TI Parallel image classification on theHIVE SO 29TH APPLIED IMAGERY PATTERN RECOGNITION WORKSHOP, PROCEEDINGS LA English DT Proceedings Paper CT 29th Applied Imagery Pattern Recognition Workshop CY OCT 16-18, 2000 CL WASHINGTON, D.C. SP IEEE Comp Soc Tech Comm Pattern Anal & Machine Intelligence, Pattern Analy & Machine Intelligence DE theHIVE; classification; parallel algorithms; Neural Networks; Gaussian Maximum Likelihood Classifier; Polynomial Discriminant Method; Mixture Model Neural Network; MIMD; SPMD AB Remotely sensed imagery represents a growing source of information to many practical applications. Technologies to rapidly process imagery data into useful information products has not kept pace with the rapidly growing volume and complexity of imagery data increasingly available from Government and commercial sources. Significant processing speed improvements have been achieved by implementation of classification methods on the Highly-parallel Integrated Virtual Environment (HIVE) - a Beowulf class system using Parallel Virtual Machine (PVM) software. This paper discusses our parallel processing architecture and how three different classification algorithms performed in this computing environment. Also discussed are conclusions and recommendations for future work to apply these techniques to more complex data and further improve the processing speeds(1). C1 NASA, Goddard Space Flight Ctr, Code 935, Greenbelt, MD 20770 USA. RP Chettri, S (reprint author), NASA, Goddard Space Flight Ctr, Code 935, 6411 Ivy Lane,Suite 300, Greenbelt, MD 20770 USA. NR 20 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-0978-9 PY 2000 BP 39 EP 46 DI 10.1109/AIPRW.2000.953601 PG 8 WC Computer Science, Artificial Intelligence; Remote Sensing; Imaging Science & Photographic Technology; Radiology, Nuclear Medicine & Medical Imaging SC Computer Science; Remote Sensing; Imaging Science & Photographic Technology; Radiology, Nuclear Medicine & Medical Imaging GA BT17G UT WOS:000172147200007 ER PT B AU Andrews, R Mah, R Jeffrey, S Aghevli, A Freitas, K Guerrero, M Papasin, R Reed, C AF Andrews, R Mah, R Jeffrey, S Aghevli, A Freitas, K Guerrero, M Papasin, R Reed, C BE Aanstoos, JV TI Multimodality tissue identification for neurosurgery: The NASA Smart Probe project SO 29TH APPLIED IMAGERY PATTERN RECOGNITION WORKSHOP, PROCEEDINGS LA English DT Proceedings Paper CT 29th Applied Imagery Pattern Recognition Workshop CY OCT 16-18, 2000 CL WASHINGTON, D.C. SP IEEE Comp Soc Tech Comm Pattern Anal & Machine Intelligence, Pattern Analy & Machine Intelligence ID BRAIN AB Real-time tissue identification can benefit procedures such as stereotactic brain biopsy, functional neurosurgery, and brain tumor excision. Optical scattering spectroscopy has been shown effective at discriminating cancer from non-cancerous conditions in the colon, bladder, and breast. The NASA Smart Probe extends the concept of "optical biopsy" by using neural network techniques to combine the output from three microsensors contained within a cannula 2.7 mm in diameter (i.e. the diameter of a stereotactic brain biopsy needle). Experimental data from five rats show the clear differentiation between tissues such as brain, nerve, fat, artery, and muscle that can be achieved with optical scattering spectroscopy alone. These data and previous findings with other modalities such as (1) analysis of the image from a fiberoptic neuroendoscope and (2) the output from a micro strain gauge suggest the Smart Probe multiple microsensor technique shows promise for real-time tissue identification in neurosurgical procedures. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Andrews, R (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-0978-9 PY 2000 BP 153 EP + DI 10.1109/AIPRW.2000.953618 PG 5 WC Computer Science, Artificial Intelligence; Remote Sensing; Imaging Science & Photographic Technology; Radiology, Nuclear Medicine & Medical Imaging SC Computer Science; Remote Sensing; Imaging Science & Photographic Technology; Radiology, Nuclear Medicine & Medical Imaging GA BT17G UT WOS:000172147200024 ER PT S AU Stoica, A AF Stoica, A GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Evolvable hardware: From on-chip circuit synthesis to evolvable space systems SO 30TH IEEE INTERNATIONAL SYMPOSIUM ON MULTIPLE-VALUED LOGIC, PROCEEDINGS SE INTERNATIONAL SYMP ON MULTIPLE-VALUED LOGIC - PROCEEDINGS LA English DT Proceedings Paper CT 30th IEEE International Symposium on Multiple-Valued Logic (ISMVL 2000) CY MAY 23-25, 2000 CL PORTLAND, OR SP Oregon Ctr Adv Technol Educ, IEEE Comp Soc Techn Comm Multiple Valued Log, Japan Res Grp Multiple Valued Log, Portland State Univ, Intel ID DESIGN AB Evolvable Hardware (EHW) refers to HW design and self-reconfiguration ruing evolution/genetic mechanisms. The paper presents an overview of some key concepts Of EHW, comments on selected applications, and presents a perspective on the development of the field. A fine-grained Field Programmable Transistor Array (FPTA) architecture for reconfigurable hardware is presented as an example of an initial effort toward evolution-oriented devices. Evolutionary experiments in simulations and with a FPTA chip in-the-loop demonstrate automatic synthesis of electronic circuits. Unconventional circuits, for which there are no textbook design guidelines, are particularly appealing to evolvable hardware. To illustrate this situation, one demonstrates here the evolution of circuits implementing parametrical connectives for fuzzy logics. In addition to synthesizing circuits for new functions, evolvable hardware call be used to preserve existing functions and achieve fault-tolerance, determining circuit configurations that circumvent the faults. These characteristics are extremely important for enabling spacecraft to survive harsh environments and to have long life. Expanding reconfiguration to other types of spacecraft hardware (i.e. optics, MEMS, etc) could lead to evolvable space systems. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Stoica, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 0 Z9 0 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA SN 0195-623X BN 0-7695-0693-3 J9 INT SYM MVL PY 2000 BP 161 EP 169 DI 10.1109/ISMVL.2000.848615 PG 3 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BQ44X UT WOS:000088368900023 ER PT B AU Kopasakis, G AF Kopasakis, G GP AIAA AIAA TI Fuzzy current-mode control and stability analysis SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB In this paper a current-mode control (CMC) methodology is developed for a buck converter by using a fuzzy logic controller. Conventional CMC methodologies are based on lead-lag compensation with voltage and inductor current feedback. In this paper the converter lead-lag compensation will be substituted with a fuzzy controller. A small-signal model of the fuzzy controller will also be developed in order to examine the stability properties of this buck converter control system. The paper develops an analytical approach, introducing fuzzy control into the area of CMC. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Kopasakis, G (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 20 EP 29 PG 10 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900004 ER PT B AU Kerslake, TW Haraburda, FM Riehl, JP AF Kerslake, TW Haraburda, FM Riehl, JP GP AIAA AIAA TI Solar power system options for the radiation and technology demonstration spacecraft SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB The Radiation and Technology Demonstration (RTD) Mission has the primary objective of demonstrating high-power (10 kilowatts) electric thruster technologies in Earth orbit. This paper discusses the conceptual design of the RTD spacecraft photovoltaic (PV) power system and mission performance analyses. These power system studies assessed multiple options for PV arrays, battery technologies and bus voltage levels. To quantify performance attributes of these power system options, a dedicated Fortran code was developed to predict power system performance and estimate system mass. The low-thrust mission trajectory was analyzed and important Earth orbital environments were modeled. Baseline power system design options are recommended on the basis of performance, mass and risk/complexity. Important findings from parametric studies are discussed and the resulting impacts to the spacecraft design and cost. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Kerslake, TW (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 33 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 47 EP 57 PG 11 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900007 ER PT B AU Hillard, GB Vayner, B AF Hillard, GB Vayner, B GP AIAA AIAA TI Spacecraft charging effects on anodized aluminum surfaces SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Hillard, GB (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 3 TC 0 Z9 0 U1 1 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 63 EP 68 PG 6 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900009 ER PT B AU Keys, DJ AF Keys, DJ GP AIAA AIAA TI Earth Observing System (EOS) TERRA spacecraft 120 volt power Subsystem (c) - Requirements, development, and implementation SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB Built by the Lockheed-Martin Corporation, the Earth Observing System (EOS) TERRA spacecraft represents the first orbiting application of a 120 Vdc high voltage spacecraft electrical power system implemented by the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC). The EOS TERRA spacecraft's launch provided a major contribution to the NASA Mission to Planet Earth program while incorporating many state of the art electrical power system technologies to achieve its mission goals. The EOS TERRA spacecraft was designed around five state-of-the-art scientific instrument packages designed to monitor key parameters associated with the earth's climate. The development focus of the TERRA electrical power system (EPS) resulted from a need for high power distribution to the EOS TERRA spacecraft subsystems and instruments and minimizing mass and parasitic losses. Also important as a design goal of the EPS was maintaining tight regulation on voltage and achieving low conducted bus noise characteristics. This paper outlines the major requirements for the EPS as well as the resulting hardware implementation approach adopted to meet the demands of the EOS TERRA low earth orbit mission. The selected orbit, based on scientific needs, to achieve the EOS TERRA mission goals is a sun-synchronous circular 98.2-degree inclination Low Earth Orbit (LEO) with a near circular average altitude of 705 kilometers. The nominal spacecraft orbit is approximately 99 minutes with an average eclipse period of about 34 minutes. The scientific goal of the selected orbit is to maintain a repeated 10:30 a.m. +/- 15 minute descending equatorial crossing which provides a fairly clear view of the earth's surface and relatively low cloud interference for the instrument observation measurements. The major EOS TERRA EPS design requirements are single fault tolerant, average orbit power delivery of 2,530 watts with a defined minimum lifetime of five years (EOL). To meet these mission requirements, while minimizing mass and parasitic power losses, the EOS TERRA project relies on 36, 096 high efficiency Gallium Arsenide (GaAs) on Germanium solar cells adhered to a deployable flexible solar array designed to provide over 5,000 watts of power at EOL. To meet the eclipse power demands of the spacecraft, EOS TERRA selected an application of two 54-cell series connected Individual Pressure Vessel (IPV) Nickel-Hydrogen (NiH2) 50 Ampere-Hour batteries. All of the spacecraft observatory electrical power is controlled via the TERRA Power Distribution Unit (PDU) which is designed to provide main bus regulation of 120 Vdc +/-4% at all load interfaces through the implementation of majority voter control of both the spacecraft's solar array sequential shunt unit (SSU) and the two battery bi-directional charge and discharge regulators. C1 NASA, Goddard Space Flight Ctr, Power Syst Branch, Elect Syst Ctr, Greenbelt, MD 20771 USA. RP Keys, DJ (reprint author), NASA, Goddard Space Flight Ctr, Power Syst Branch, Elect Syst Ctr, Greenbelt, MD 20771 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 197 EP 206 PG 10 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900028 ER PT B AU Geng, SM Schwarze, GE Niedra, JM AF Geng, SM Schwarze, GE Niedra, JM GP AIAA AIAA TI A 3-D magnetic analysis of a linear alternator for a Stirling power system SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB The NASA Glenn Research Center and the Department of Energy (DOE) are developing advanced radioisotope Stirling convertors, under contract with Stirling Technology Company (STC), far space applications. Of critical importance to the successful development of the Stirling convertor for space power applications is the development of a lightweight and highly efficient linear alternator. This paper presents a 3-D finite element method (FEM) approach for evaluating Stirling convertor linear alternators. Preliminary correlations with open-circuit voltage measurements provide an encouraging level of confidence in the model. Spatial plots of magnetic field strength (H) are presented in the region of the exciting permanent magnets. These plots identify regions of high H, where at elevated temperature and under electrical load, the potential to after the magnetic moment of the magnets exists. This implies the need for further testing and analysis. C1 NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Geng, SM (reprint author), NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 232 EP 237 PG 6 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900032 ER PT B AU Goodnight, TW Hughes, WO McNelis, ME AF Goodnight, TW Hughes, WO McNelis, ME GP AIAA AIAA TI Dynamic capability of an operating Stirling convertor SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB The NASA John H. Glenn Research Center and the U.S. Department of Energy are currently developing a Stirling convertor for use as an advanced spacecraft power system for future NASA deep-space missions. NASA Headquarters has recently identified the Stirling technology generator for potential use as the spacecraft power system for two of NASA's new missions, the Europa Orbiter and the Solar Probe missions (planned for launch in 2006 and 2007 respectively). As part of the development of this power system, a Stirring Technology Demonstration Convertor was vibration tested at NASA John H. Glenn Research Center to verify its survivability and capability of withstanding the harsh dynamic environment typically seen by the spacecraft when it is launched by an expendable launch vehicle. The Technology Demonstration Convertor was fully operational (producing power) during the random vibration testing. The output power of the convertor and other convertor performance indicators were measured during the testing, and these results are discussed in this paper. Numerous accelerometers and force gauges also were used to provide information an the dynamic characteristics of the Technology Demonstration Convertor and as an indication of any possible damage due to the vibration. These measurements will also be discussed in this paper. The vibration testing of the Stirling Technology Demonstration Convertor was extremely successful. The Technology Demonstration Convertor survived all its vibration testing with no structural damage or functional performance degradation. As a result of this testing, the Stirling convector's capability to withstand vibration has been demonstrated, enabling its usage in future spacecraft power systems. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Goodnight, TW (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 238 EP 248 PG 11 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900033 ER PT B AU Thieme, LG Schreiber, JG AF Thieme, LG Schreiber, JG GP AIAA AIAA TI NASA GRC technology development project for a Stirling radioisotope power system SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB NASA Glenn Research Center (GRC), the Department of Energy (DOE), and Stirling Technology Company (STC) are developing a Stirling convertor for an advanced radioisotope power system to provide spacecraft on-board electric power for NASA deep space missions. NASA GRC is conducting an in-house project to provide convertor, component, and materials testing and evaluation in support of the overall power system development. A first characterization of the DOE/STC 55-We Stirling Technology Demonstration Convertor (TDC) under the expected launch random vibration environment was recently completed in the NASA GRC Structural Dynamics Laboratory. Two TDCs also completed an initial EMI characterization at NASA GRC while being tested in a synchronized, opposed configuration. Materials testing is underway to support a life assessment of the heater head, and magnet characterization and aging tests have been initiated. Test facilities are now being established for an independent convertor performance verification and technology development. A preliminary FMEA, initial FEA for the linear alternator, ionizing radiation survivability assessment, and radiator parametric study have also been completed. This paper will discuss the status, plans, and results to date for these efforts. C1 NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Thieme, LG (reprint author), NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. NR 21 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 249 EP 258 PG 10 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900034 ER PT B AU Bartolotta, PA Bowman, RR Krause, DL Halford, GR AF Bartolotta, PA Bowman, RR Krause, DL Halford, GR GP AIAA AIAA TI Long-term durability analysis of a 100,000+hr Stirling power convertor heater head SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB DOE and NASA have identified Stirling Radioisotope Power Systems (SRPS) as a candidate power system for future deep space exploration missions. As a part of this effort, NASA has initiated a long-term durability project for critical hot section components of the Stirling power convertor to qualify flight hardware. This project will develop a life prediction methodology that utilizes short-term (t < 20,000 hr) test data to verify long-term (t > 100,000 hr) design life. The project consists of generating a materials database for the specific heat of alloy, evaluation of critical hermetic sealed joints, life model characterization, and model verification. This paper will describe the qualification methodology being developed and provide a status for this effort. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Bartolotta, PA (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 259 EP 265 PG 7 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900035 ER PT B AU Mondt, JF AF Mondt, JF GP AIAA AIAA TI Advanced radioisotope power systems requirements for potential deep space missions SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB This paper describes future mission power requirements for missions being investigated to accomplish NASA's Solar System Exploration (SSE) theme. Many potential missions to the outer planets (Jupiter and beyond) require advanced radioisotope power systems (RPS). Technology development for Advanced RPSs is being carried out as apart of NASA's Solar System Exploration Technology Program. The power levels for future planetary deep space science missions are broken down into the following four classes. Milliwatt-class (40 to 100milliwatt) that could provide both thermal and electric power for Mars weather stations. One to two-watt class for small in situ surface science laboratories and for aerobot atmospheric science laboratories for bodies in the solar system. Ten to twenty-watt class for micro satellites in orbit, surface science stations and aerobots. One hundred to three hundred watt-class to power orbiter science spacecraft, to power drills to obtain core samples of outer planet bodies, for powering subsurface hydrobots and cryobots on accessible bodies and for data handling and communicating data from small orbiters, surface laboratories, aerobots and hydrobots back to Earth. Advanced RPSs in the one hundred-watt class are also favored over solar power for obtaining comet samples on extended-duration comet missions. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Mondt, JF (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 444 EP 448 PG 5 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900060 ER PT B AU Truong, LV Wolff, FJ Dravid, NV AF Truong, LV Wolff, FJ Dravid, NV GP AIAA AIAA TI Simulation of flywheel electrical system for aerospace applications SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB A Flywheel Energy Storage Demonstration Project was initiated at NASA Glenn Research Center as a possible replacement for the Battery Energy Storage System on the International Space Station (ISS). While the hardware fabrication work was performed at a contractor's place and at a university, the related simulation activity was begun at NASA Glenn Research Center. At the top level, the primary electrical system of ISS is simulated with one Battery Charge and Discharge Unit (BCDU) replaced by the Flywheel Energy Storage Unit (FESU) is described in another paper. The FESU consists of a Permanent Magnet Synchronous Motor/Generator, PMSM, (connected to the flywheel), the Power Electronics that connects the PMSM to the ISS de bus, and the associated controller. While the PMSM model is still under development, the rest of the FESU model is described in this paper. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Truong, LV (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 3 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 601 EP 608 PG 8 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900078 ER PT B AU Smart, MC Ratnakumar, BV Whitcanack, L Surampudi, S Lowry, L Gitzendanner, R Marsh, C Puglia, F Byers, J Marsh, R AF Smart, MC Ratnakumar, BV Whitcanack, L Surampudi, S Lowry, L Gitzendanner, R Marsh, C Puglia, F Byers, J Marsh, R GP AIAA AIAA TI Performance characteristics of yardney lithium-ion cells for the Mars 2001 Lander application SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB NASA requires lightweight rechargeable batteries for future missions to Mars and the outer planets that are capable of operating over a wide range of temperatures, with high specific energy and energy densities. Due to the attractive performance characteristics, Lithium-ion batteries have been identified as the battery chemistry of choice for a number of future applications, including Mars Revers' and Landers(2,3). The Mars 2001 Lander(Mars Surveyor Program MSP 01) will be among one of the first missions which will utilize Lithium-ion technology. This application will require two Lithium-ion batteries, each being 28 V (eight cells), 25 Ah and 9 kg (18 kg total). In addition to the requirement of being able to supply at least 90 cycles on the surface of Mars after a 1 year storage and cruise time, the battery must be capable of operation (both charge and discharge) over a wide temperature range (-20 degrees C to +40 degrees C), with tolerance to non-operational excursions to -30 degrees C and 50 degrees C. To assess the viability of lithium-ion cells for these applications, a number of performance characterization tests have been performed on state-of-art Yardney lithium-ion cells, including: assessing the room temperature cycle life, low temperature cycle life (-20 degrees C), rate capability as a function of temperature (-30 degrees to 40 degrees C), pulse capability, self-discharge and storage characteristics, as well as, mission profile capability. This paper will describe the Mars 2001 Lander mission battery requirements and will contain results of the cell testing conducted to-date in support of the mission. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Smart, MC (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 629 EP 637 PG 9 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900082 ER PT B AU Ratnakumar, BV Smart, MC Ewell, R Surampudi, S Marsh, R AF Ratnakumar, BV Smart, MC Ewell, R Surampudi, S Marsh, R GP AIAA AIAA TI Performance characteristics of lithium-ion cells for Mars sample return Athena rover SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut ID ELECTROLYTES; BATTERIES AB Future planetary exploration missions, especially Landers and Revers, will utilize lithium ion rechargeable batteries, due to their advantages of reduced mass and volume compared with nonlithium systems. In addition to the usual requirements of high specific energy and energy density, some applications, e.g., Mars Landers and Revers, require the batteries to be functional over wide range of temperatures, i.e., -20 to +40 degrees C. Several prototypes with modified chemistries commensurate with these mission needs were built by U.S. battery manufacturers, in conjunction with a NASA-DoD Interagency developmental effort and are being tested at JPL in the last couple of years. The proposed Mars Rover will have three lithium ion batteries (with one serving the purpose of redundancy) connected in parallel, each with four 6-9 Ah cells in series, to augment the solar array. The charger for these Rover batteries is being designed and built in-house. In this paper, we will present several performance characterization tests, including cycle life at different temperatures, rate capability at various charge/discharge rates and temperatures and real time and accelerated storage, which were carried out on these prototype cells in support of the Mars exploration missions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ratnakumar, BV (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 638 EP 645 PG 8 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900083 ER PT B AU Hoffman, DJ Kerslake, TW Hepp, AF Jacobs, MK Ponnusamy, D AF Hoffman, DJ Kerslake, TW Hepp, AF Jacobs, MK Ponnusamy, D GP AIAA AIAA TI Thin-film photovoltaic solar array parametric assessment SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB This paper summarizes a study that had the objective to develop a model and parametrically determine the circumstances for which lightweight thin-film photovoltaic solar arrays would be more beneficial, in terms of mass and cost, than arrays using high-efficiency crystalline solar cells. Previous studies considering arrays with near-term thin-film technology for Earth orbiting applications are briefly reviewed. The present study uses a parametric approach that evaluated the performance of lightweight thin-film arrays with cell efficiencies ranging from 5% to 20%. The model developed for this study is described in some detail. Similar mass and cost trends for each array option were found across eight missions of various power levels in locations ranging from Venus to Jupiter. The results for one specific mission, a main belt asteroid tour, indicate that only moderate thin-film cell efficiency (similar to 12%) is necessary to match the mass of arrays using crystalline cells with much greater efficiency (35% multi-junction GaAs based and 20% thin-silicon). Regarding cast, a 12% efficient thin-film array is projected to cost about half as much as a 4-junction GaAs array. While efficiency improvements beyond 12% did not significantly further improve the mass and cost benefits for thin-film arrays, higher efficiency will be needed to mitigate the spacecraft-level impacts associated with large deployed array areas. A low-temperature approach to depositing thin-film cells on lightweight, flexible plastic substrates is briefly described. The paper concludes with the observation that with the characteristics assumed for this study, ultra-lightweight arrays using efficient, thin-film cells on flexible substrates may become a leading alternative for a wide variety of space missions. C1 NASA, Glenn Res Ctr, Cleveland, OH USA. RP Hoffman, DJ (reprint author), NASA, Glenn Res Ctr, Cleveland, OH USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 670 EP 680 PG 11 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900087 ER PT B AU Truong, L Wolff, F Dravid, N Li, PL AF Truong, L Wolff, F Dravid, N Li, PL GP AIAA AIAA TI Simulation of the interaction between flywheel energy storage and battery energy storage on the International Space Station SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB Replacement of one module of the battery charge discharge unit (BCDU) of the international Space Station (ISS) by a flywheel energy storage unit (FESU) is under consideration. Integration of these two dissimilar systems is likely to surface difficulties in areas of system stability and fault protection Other issues that need to be addressed include flywheel charge and discharge profiles and their effect on the ISS power system as well as filter sizing for power quality purposes. This paper describes a SABER(TM) based simulation to study these issues. C1 NASA, GRC, Cleveland, OH USA. RP Truong, L (reprint author), NASA, GRC, Cleveland, OH USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 848 EP 854 PG 7 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900111 ER PT B AU Kankam, MD Lyons, VJ Hoberecht, MA Tacina, RR Hepp, AF AF Kankam, MD Lyons, VJ Hoberecht, MA Tacina, RR Hepp, AF GP AIAA AIAA TI "Recent GRC aerospace technologies applicable to terrestrial energy systems" SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB This paper is an overview of a wide range of recent aerospace technologies under development at the NASA Glenn Research Center, in collaboration with other NASA centers, government agencies, industry and academia The focussed areas are space solar power, advanced power management and distribution systems, Stirling cycle conversion systems, fuel cells, advanced thin film photovoltaics and batteries, and combustion technologies. The aerospace-related objectives of the technologies are generation of space power, development of cost-effective and reliable, high performance power systems, cryogenic applications, energy storage, and reduction in gas-turbine emissions, with attendant clean jet engines. The terrestrial energy applications of the technologies include augmentation of bulk power in ground power distribution systems, and generation of residential, commercial and remote power, as well as promotion of pollution-free environment via reduction in combustion emissions. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Kankam, MD (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 5 TC 0 Z9 0 U1 1 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 865 EP 875 PG 11 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900113 ER PT B AU Jaworske, DA Skowronski, TJ AF Jaworske, DA Skowronski, TJ GP AIAA AIAA TI Optical efficiency of a refractive secondary concentrator SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB Refractive considered as thermal power secondary concentrators are being as an optical component in solar thermal power and propulsion systems. To evaluate the impact of a refractive secondary concentrator on the overall efficiency of the optical system, the optical efficiency of an acrylic refractive secondary concentrator prototype was evaluated on an optics bench. Light from a laser was allowed to enter the refractive secondary concentrator from a variety of positions, and an integrating sphere was used to collect the exiting light. Energy output of the refractive secondary concentrator was compared to energy input. Several mathematical models were used to describe potential flux distributions impinging on the front surface of the refractive secondary concentrator. For uniform illumination, the optical throughput was found to be 0.874. Different flux profiles resulted in optical throughputs in the range of 0.857 to 0.889. An antireflective coating added to the refractive secondary concentrator should increase optical throughput further. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Cleveland State Univ, Cleveland, OH 44121 USA. RP Jaworske, DA (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 1098 EP 1102 PG 5 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900144 ER PT B AU Wong, WA Geng, SM Castle, CH Macosko, RP AF Wong, WA Geng, SM Castle, CH Macosko, RP GP AIAA AIAA TI Design, fabrication and test of a high efficiency refractive secondary concentrator for solar applications SO 35TH INTERSOCIETY ENERGY CONVERSION ENGINEERING CONFERENCE & EXHIBIT (IECEC), VOLS 1 AND 2, TECHNICAL PAPERS LA English DT Proceedings Paper CT 35th Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC) CY JUL 24-28, 2000 CL Las Vegas, NV SP Amer Inst Aeronaut & Astronaut AB Common to many of the space applications that utilize solar thermal energy such as electric power conversion, thermal propulsion, and furnaces, is a need for highly efficient, solar concentration systems. An effort is underway to develop the refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. When used in combination with advanced primary concentrators, the refractive secondary concentrator enables very high system concentration ratios (10,000 to 1) and very high temperatures (> 2000 K). Presented is an overview of the effort at the NASA Glenn Research Center to evaluate the performance of a prototype single crystal sapphire refractive secondary concentrator and to compare the performance with analytical models. The effort involves the design and fabrication of a secondary concentrator, design and fabrication of a calorimeter and its support hardware, calibration of the calorimeter, testing of the secondary concentrator in NASA Glenn's Tank 6 solar thermal vacuum facility, and comparing the test results with predictions. Test results indicate an average throughput efficiency of 87%. It is anticipated that reduction of a known reflection loss with an anti-reflective coating would result in a secondary concentrator throughput efficiency of approximately 93%. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Analex Corp, Brook Pk, OH 44142 USA. RP Wong, WA (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-375-5 PY 2000 BP 1117 EP 1125 PG 9 WC Engineering, Aerospace SC Engineering GA BQ77B UT WOS:000089466900147 ER EF