FN Thomson Reuters Web of Science™ VR 1.0 PT J AU WALSH, D POPE, D DANFORD, M HUFF, T AF WALSH, D POPE, D DANFORD, M HUFF, T TI THE EFFECT OF MICROSTRUCTURE ON MICROBIOLOGICALLY INFLUENCED CORROSION SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Article C1 BIOINDUSTRIES TECHNOL,GEORGETOWN,TX. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. SVERDRUP,HUNTSVILLE,AL. RP WALSH, D (reprint author), CALIF POLYTECH STATE UNIV SAN LUIS OBISPO,SAN LUIS OBISPO,CA 93407, USA. NR 34 TC 36 Z9 45 U1 0 U2 3 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1047-4838 J9 JOM-J MIN MET MAT S JI JOM-J. Miner. Met. Mater. Soc. PD SEP PY 1993 VL 45 IS 9 BP 22 EP 30 PG 9 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA LW185 UT WOS:A1993LW18500006 ER PT J AU HUEBNER, LD TATUM, KE AF HUEBNER, LD TATUM, KE TI COMPUTATIONAL EFFECTS OF INLET REPRESENTATION ON POWERED HYPERSONIC, AIRBREATHING MODELS SO JOURNAL OF AIRCRAFT LA English DT Article AB Computational results are presented to illustrate the powered aftbody effects of representing the scramjet inlet on a generic hypersonic vehicle with a fairing, to divert the external flow, as compared to an operating flow-through scramjet inlet. This study is pertinent to the ground testing of hypersonic, airbreathing models employing scramjet exhaust flow simulation in typical small-scale hypersonic wind tunnels. The comparison of aftbody effects due to inlet representation is well-suited for computational study, since small model size typically precludes the ability to ingest flow into the inlet and perform exhaust simulation at the same time. Two-dimensional analysis indicates that, although flowfield differences exist for the two types of inlet representations, little, if any, difference in surface aftbody characteristics is caused by fairing over the inlet. RP HUEBNER, LD (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1993 VL 30 IS 5 BP 571 EP 577 DI 10.2514/3.46384 PG 7 WC Engineering, Aerospace SC Engineering GA MA615 UT WOS:A1993MA61500002 ER PT J AU SILVA, WA AF SILVA, WA TI APPLICATION OF NONLINEAR-SYSTEMS THEORY TO TRANSONIC UNSTEADY AERODYNAMIC RESPONSES SO JOURNAL OF AIRCRAFT LA English DT Article AB A methodology is presented for using the Volterra-Wiener theory of nonlinear systems in aeroservoelastic (ASE) analyses and design. The theory is applied to the development of nonlinear aerodynamic response models that can be defined in state-space form and are, therefore, appropriate for use in modern control theory. The Volterra-Wiener theory relies on the identification of nonlinear kernels that can be used to predict the response of a nonlinear system due to an arbitrary input. A numerical kernel identification technique, based on unit impulse responses, is presented and applied to a simple bilinear, single-input-single-output (SISO) system. The linear kernel (unit impulse response) and the nonlinear second-order kernel of the system are numerically identified and compared with the exact, analytically defined linear and second-order kernels. This kernel identification technique is then applied to the computational aeroelasticity program-transonic small disturbance (CAP-TSD) code for identification of the linear and second-order kernels of a NACA64A010 rectangular wing undergoing pitch at M = 0.5, M = 0.85 (transonic), and M = 0.93 (transonic). Results presented demonstrate the feasibility of this approach for use with nonlinear, unsteady aerodynamic responses. RP SILVA, WA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 47 Z9 49 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1993 VL 30 IS 5 BP 660 EP 668 DI 10.2514/3.46395 PG 9 WC Engineering, Aerospace SC Engineering GA MA615 UT WOS:A1993MA61500013 ER PT J AU CLIFF, SE THOMAS, SD AF CLIFF, SE THOMAS, SD TI EULER EXPERIMENT CORRELATIONS OF SONIC-BOOM PRESSURE SIGNATURES SO JOURNAL OF AIRCRAFT LA English DT Article AB The ability of inviscid computational fluid dynamics (CFD) codes to compute sonic boom pressure signatures is examined using three different codes that solve the Euler equations of fluid flow on structured hexahedral and unstructured tetrahedral grids. The results of these Euler codes were evaluated by comparing the computed pressure signatures with near-field experimental data. The computational pressure signatures were determined at distances of one body length or less below the configuration in the plane of symmetry and extrapolated to experimental distances using the waveform parameter method. The extrapolated CFD pressure signatures gave acceptable correlations with experimental data, provided that tine grids were used between the surface and the spatial location of the pressure signature. RP CLIFF, SE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1993 VL 30 IS 5 BP 669 EP 675 DI 10.2514/3.46396 PG 7 WC Engineering, Aerospace SC Engineering GA MA615 UT WOS:A1993MA61500014 ER PT J AU ATWOOD, CA VANDALSEM, WR AF ATWOOD, CA VANDALSEM, WR TI FLOWFIELD SIMULATION ABOUT THE STRATOSPHERIC OBSERVATORY FOR INFRARED ASTRONOMY SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT 30TH AEROSPACE SCIENCES MEETING AND EXHIBIT CY JAN 06-09, 1992 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB The Reynolds-averaged Navier-Stokes equations have been applied to stratospheric observatory for infrared astronomy (SOFIA) configurations. Comparisons between numerical and experimental results are made in two dimensions for free shear layers and a rectangular cavity, and in three dimensions for simplified SOFIA geometries. Dominant acoustic behavior of the cavity flows compare well with experiment. The sensitivity of the solutions to changes in grid cell size and artificial dissipation levels are shown. Furthermore, optical path distortion due to the flowfield is modeled using geometrical constructs. The results demonstrate the viability and usefulness of the present computational method for this class of unsteady applications. RP ATWOOD, CA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 8 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1993 VL 30 IS 5 BP 719 EP 727 DI 10.2514/3.46403 PG 9 WC Engineering, Aerospace SC Engineering GA MA615 UT WOS:A1993MA61500021 ER PT J AU ROGERS, SE WILTBERGER, NL KWAK, D AF ROGERS, SE WILTBERGER, NL KWAK, D TI EFFICIENT SIMULATION OF INCOMPRESSIBLE VISCOUS-FLOW OVER SINGLE AND MULTIELEMENT AIRFOILS SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT 30TH AEROSPACE SCIENCES MEETING AND EXHIBIT CY JAN 06-09, 1992 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB The incompressible, viscous, turbulent flow over single and multielement airfoils is numerically simulated in an efficient manner by solving the incompressible Navier-Stokes equations. The solution algorithm uses the method of pseudocompressibility with an upwind-differencing scheme for the convective fluxes, and an implicit line-relaxation scheme. The motivation for this work includes interest in studying high-lift takeoff and landing configurations of various aircraft. In particular, accurate computation of lift and drag at various angles of attack up to stall is desired. Two different turbulence models are tested in computing the flow over a NACA 4412 airfoil; an accurate prediction of stall is obtained. The approach used for multielement airfoils involves the use of multiple zones of structured grids fitted to each element. Two different approaches are compared: 1) a patched system of grids, and 2) an overlaid Chimera system of grids. Computational results are presented for two-element, three-element, and four-element airfoil configurations. Generally, good agreement with experimental surface pressure coefficients is seen. The code converges in less than 200 iterations, requiring on the order of 1 min of CPU time on a CRAY YMP per element in the airfoil configuration. RP ROGERS, SE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 12 Z9 12 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1993 VL 30 IS 5 BP 736 EP 743 DI 10.2514/3.46405 PG 8 WC Engineering, Aerospace SC Engineering GA MA615 UT WOS:A1993MA61500023 ER PT J AU SCOTT, RC POTOTZKY, AS PERRY, B AF SCOTT, RC POTOTZKY, AS PERRY, B TI COMPUTATION OF MAXIMIZED GUST LOADS FOR NONLINEAR AIRCRAFT USING MATCHED-FILTER-BASED SCHEMES SO JOURNAL OF AIRCRAFT LA English DT Article AB This article describes and illustrates two matched-filter-theory-based schemes for obtaining maximized and time-correlated gust loads for a nonlinear airplane. The first scheme is computationally fast because it uses a simple one-dimensional search procedure to obtain its answers. The second scheme is computationally slow because ft uses a more complex multidimensional search procedure to obtain its answers, but it consistently provides slightly higher maximum loads than the first scheme. Both schemes are illustrated with numerical examples involving a nonlinear control system. RP SCOTT, RC (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 0 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1993 VL 30 IS 5 BP 763 EP 768 DI 10.2514/3.46409 PG 6 WC Engineering, Aerospace SC Engineering GA MA615 UT WOS:A1993MA61500027 ER PT J AU HAKIMZADEH, R MOLLER, HJ BAILEY, SG AF HAKIMZADEH, R MOLLER, HJ BAILEY, SG TI EVALUATION OF THE MINORITY-CARRIER DIFFUSION LENGTH AND EDGE SURFACE-RECOMBINATION VELOCITY IN GAAS P/N SOLAR-CELLS - RESPONSE SO JOURNAL OF APPLIED PHYSICS LA English DT Note AB This reply to Dr. Luke's comment on our findings [J. Appl. Phys. 72, 2919 (1992)] explains the intent of our work and answers the questions raised. C1 TECH UNIV HAMBURG,W-2100 HAMBURG 90,GERMANY. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP HAKIMZADEH, R (reprint author), SVERDRUP TECHNOL INC,LEWIS RES GRP,BROOKPARK,OH 44142, USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 1 PY 1993 VL 74 IS 5 BP 3622 EP 3623 DI 10.1063/1.355281 PG 2 WC Physics, Applied SC Physics GA LV391 UT WOS:A1993LV39100106 ER PT J AU GREBOWSKY, JM HOEGY, WR CHEN, TC AF GREBOWSKY, JM HOEGY, WR CHEN, TC TI HIGH-LATITUDE FIELD-ALIGNED LIGHT-ION FLOWS IN THE TOPSIDE IONOSPHERE DEDUCED FROM ION COMPOSITION AND PLASMA TEMPERATURES SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT 20TH GENERAL ASSEMBLY OF THE INTERNATIONAL UNION OF GEODESY AND GEOPHYSICS : IONOSPHERIC STRUCTURES AND PROCESSES : THEIR RELATION AND FEEDBACK TO THE MAGNETOSPHERE CY AUG, 1991 CL VIENNA, AUSTRIA SP INT UNION GEODESY & GEOPHYS ID ATMOSPHERE EXPLORER-C; F-REGION; MASS SPECTROMETER AB Under the assumption of steady state conditions, the continuity and momentum equations can be solved locally for magnetic field aligned ion flow velocities given the local ion concentrations, electron and ion temperatures and their vertical gradients, as well as the neutral composition derived from the MSIS model. Using a comprehensive ionospheric data set comprised of all available ion composition and plasma temperature measurements from satellites, the vertical distributions of ion composition and plasma temperatures are defined from middle latitudes up into the polar cap for summer conditions for altitudes below approximately 1200 km. These data are sufficient to allow a numerical estimation of the latitudinal variation of the light ion outflows from within the plasmasphere to the polar wind regions. The altitude at which significant light ion outflow begins is found to be lower during solar minimum conditions than during solar maximum. The H+ outward speeds are of the order of 1 km/s near 1100 km (the limit of the observations) during solar maximum but attain several km/s speeds for solar minimum. He+ shows a similar altitude development of flow but attains polar cap speeds much less than 1 km/s at altitudes below 1100 km, particularly under solar maximum conditions. Outward flows are also found in the topside F-region for noontime magnetic flux tubes within the plasmasphere. C1 UNIV GREENBELT,RES FDN,GREENBELT,MD 20770. RP GREBOWSKY, JM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Grebowsky, Joseph/I-7185-2013 NR 24 TC 9 Z9 9 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD SEP-OCT PY 1993 VL 55 IS 11-12 BP 1605 EP 1617 DI 10.1016/0021-9169(93)90137-N PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP652 UT WOS:A1993LP65200013 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H PETTERSSON, LGM AF BAUSCHLICHER, CW PARTRIDGE, H PETTERSSON, LGM TI FRANCK-CONDON FACTORS FOR PHOTODETACHMENT FROM LIO-, NAO-, AND KO- SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CORE POLARIZATION POTENTIALS; GAUSSIAN-BASIS SETS; GTO BASIS-SETS; ABINITIO CALCULATIONS; 2ND-ROW ATOMS; ALKALI; 1ST-ROW; STATES; SPECTROSCOPY; OXIDES AB The 1SIGMA+, 3SIGMA+, 1PI, and 3PI states of the negative ions and the 2PI and 2SIGMA+ states of the neutral alkali oxides are studied at high levels of theory. The calculations show that ground state of the negative ions changes from 3PI for LiO- to 1SIGMA+ for KO-. Although the calculations give a 3PI ground state for NaO-, we cannot rule out the possibility that the very low-lying 1SIGMA+ state is the true ground state. The Franck-Condon factors for photodetachment of an electron from the 1SIGMA+ and/or 3PI states of the negative ion are presented to help interpret photodetachment experiments. Our best results for the A 2SIGMA+-X 2PI separations in LiO and NaO are 2496 and 2061 cm-1, which are in excellent agreement with that deduced (2516 and 2018 cm-1) from experiment. C1 UNIV STOCKHOLM,INST THEORET PHYS,S-11346 STOCKHOLM,SWEDEN. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Pettersson, Lars/F-8428-2011; Pettersson, Lars/J-4925-2013 OI Pettersson, Lars/0000-0003-1133-9934 NR 32 TC 11 Z9 11 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 1 PY 1993 VL 99 IS 5 BP 3654 EP 3658 DI 10.1063/1.466163 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LU722 UT WOS:A1993LU72200057 ER PT J AU KLEPEIS, NE EAST, ALL CSASZAR, AG ALLEN, WD LEE, TJ SCHWENKE, DW AF KLEPEIS, NE EAST, ALL CSASZAR, AG ALLEN, WD LEE, TJ SCHWENKE, DW TI THE [FHCI]- MOLECULAR ANION - STRUCTURAL ASPECTS, GLOBAL SURFACE, AND VIBRATIONAL EIGENSPECTRUM SO JOURNAL OF CHEMICAL PHYSICS LA English DT Review ID QUANTUM REACTIVE SCATTERING; INTEGRAL CROSS-SECTIONS; GAUSSIAN-BASIS SETS; POTENTIAL-ENERGY SURFACES; SELF-CONSISTENT-FIELD; CYCLOTRON RESONANCE DETERMINATION; LEVEL CORRELATED CALCULATIONS; ELECTRON CORRELATION-ENERGY; KOHN VARIATIONAL PRINCIPLE; HYDROGEN BIFLUORIDE ANION AB The [FHCI]- molecular anion has been investigated in detail by means of state-of-the-art ab initio electronic structure methods, including restricted Hartree-Fock (RHF), Moller-Plesset perturbation theory (MP2-MP4), and coupled-cluster and Brueckner methods incorporating various degrees of excitation [CCSD, CCSD (T), BD, BD (T), and BD (TQ) ]. The one-particle Gaussian basis sets ranged in quality from F[6s4p2d], Cl[10s7p2d], and H[4s2p] to F[18s13p6d4f], Cl[20s14p7d5f], and H[8s3p2d1f]. The first phase of the investigation focused on the prediction of thermochemical, spectroscopic, and bonding properties of [FHCl]- and the chemical interpretation thereof The final proposals for the geometric structure and binding energy of the complex are r(e)(H-F)=0.963+/-0.003 angstrom, R(e)(H-Cl)=1.925+/-0.015 angstrom, and D0(HF +Cl-)=21.8+/-0.4 kcal mol-1. A Morokuma decomposition of the ion-molecule bonding gave the following electrostatic (ES), polarization (PL), exchange repulsion (EX), dispersion (DISP), and charge-transfer plus higher-order mixing (CT+MIX) components of the vibrationless complexation energy: - 27.3 (ES), - 5.2 (PL), + 18.3 (EX), - 4.5 (DISP), and - 5.0 (CT + MIX) kcal mol-1. The second phase of the work involved the construction of a CCSD global surface from 208 and 228 energy points for linear and bent conformations, respectively, these being fit to rms errors of only 3.9 and 9.3 cm-1, respectively, below 8000 cm-1. The surface was represented by a flexible analytic form which reproduces the quartic force field at equilibrium, exhibits the proper asymptotic properties, and is generally applicable to ion-molecule systems. The final phase of the study entailed the determination of converged J=0 and J=1 variational eigenstates of the [FHCl]- surface to near the HF + Cl- dissociation threshold by employing Jacobi coordinates and vibrational configuration interaction expansions in terms of natural modals. The fundamental vibrational frequencies given by the analysis were nu1=247, nu2=876, and nu3=2884 cm-1. The complete vibrational eigenspectrum was then analyzed in terms of several contemporary dynamical issues, including vibrational adiabaticity, anharmonic resonances, densities of high-lying states, and signatures of quantum ergodicity. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP KLEPEIS, NE (reprint author), STANFORD UNIV, DEPT CHEM, STANFORD, CA 94305 USA. RI Csaszar, Attila/A-5241-2009; Lee, Timothy/K-2838-2012; Allen, Wesley/C-9867-2010; schwenke, david/I-3564-2013; OI Allen, Wesley/0000-0002-4288-2297; Klepeis, Neil/0000-0002-6934-3242 NR 200 TC 33 Z9 33 U1 0 U2 8 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 1 PY 1993 VL 99 IS 5 BP 3865 EP 3897 DI 10.1063/1.466133 PG 33 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LU722 UT WOS:A1993LU72200078 ER PT J AU POLLACK, JB RIND, D LACIS, A HANSEN, JE SATO, M RUEDY, R AF POLLACK, JB RIND, D LACIS, A HANSEN, JE SATO, M RUEDY, R TI GCM SIMULATIONS OF VOLCANIC AEROSOL FORCING .1. CLIMATE CHANGES INDUCED BY STEADY-STATE PERTURBATIONS SO JOURNAL OF CLIMATE LA English DT Article ID GENERAL-CIRCULATION MODELS; EL-CHICHON; FEEDBACK PROCESSES; MIDDLE ATMOSPHERE; SATELLITE DATA; CLOUD; ERUPTION; IMPACT; CO2; STRATOSPHERE AB The authors have used the Goddard Institute for Space Studies Climate Model II to simulate the response of the climate system to a spatially and temporally constant forcing by volcanic aerosols having an optical depth of 0.15. The climatic changes produced by long-term volcanic aerosol forcing are obtained by differencing this simulation and one made for the present climate with no volcanic aerosol forcing. These climatic changes are compared with those obtained with the same climate model when the CO2 content of the atmosphere was doubled (2 x CO2) and when the boundary conditions associated with the peak of the last ice age were used (18 K). In all three cases, the absolute magnitude of the change in the globally averaged air temperature at the surface is approximately the same, approximately 5 K. The simulations imply that a significant cooling of the troposphere and surface can occur at times of closely spaced, multiple, sulfur-rich volcanic explosions that span time scales of decades to centuries, such as occurred at the end of the nineteenth and beginning of the twentieth centuries. The steady-state climate response to volcanic forcing includes a large expansion of sea ice, especially in the Southern Hemisphere; a resultant large increase in surface and planetary albedo at high latitudes; and sizable changes in the annually and zonally averaged air temperature, DELTAT; DELTAT at the surface (DELTAT(s)) does not sharply increase with increasing latitude, while DELTAT in the lower stratosphere is positive at low latitudes and negative at high latitudes. In certain ways, the climate response to the three different forcings is similar. Direct radiative forcing accounts for 30% and 25% of the total DELTAT(s) in the volcano and 2 x CO2 runs, respectively. Changes in atmospheric water vapor act as the most important feedback, and are positive in all three cases. Albedo feedback is a significant, positive feedback at high latitudes in all three simulations, although the land ice feedback is prominent only in the 18 K run. In other ways, the climate response to the three forcings is quite different. The latitudinal profiles of DELTAT(s) for the three runs differ considerably, reflecting significant variations in the latitudinal profiles of the primary radiative forcing. Partially as a result of this difference in the DELTAT(s) profiles, changes in eddy kinetic energy, heat transport by atmospheric eddies, and total atmospheric heat transport are quite different in the three cases. In fact, atmospheric heat transport acts as a positive feedback at high latitudes in the volcano run and as a negative feedback in the other two runs. These results raise questions about the ease with which atmospheric heat transport can be parameterized in a simple way in energy balance climate models. C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP POLLACK, JB (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. RI Lacis, Andrew/D-4658-2012 NR 45 TC 18 Z9 18 U1 1 U2 7 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD SEP PY 1993 VL 6 IS 9 BP 1719 EP 1742 DI 10.1175/1520-0442(1993)006<1719:GSOVAF>2.0.CO;2 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LY869 UT WOS:A1993LY86900004 ER PT J AU JOHNSON, WS AF JOHNSON, WS TI INTRODUCTION TO WORKSHOP ON CRACK-GROWTH BEHAVIOR OF CONTINUOUS FIBER-REINFORCED TITANIUM MATRIX COMPOSITES (TMCS) SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Editorial Material RP JOHNSON, WS (reprint author), NASA,LANGLEY RES CTR,MS 188E,HAMPTON,VA 23681, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD FAL PY 1993 VL 15 IS 3 BP 209 EP 209 PG 1 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA MA274 UT WOS:A1993MA27400004 ER PT J AU HILLBERRY, BM JOHNSON, WS AF HILLBERRY, BM JOHNSON, WS TI FATIGUE-CRACK SPACING IN THE MATRIX OF A CONTINUOUS FIBER SCS-6/TI COMPOSITE SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article; Proceedings Paper CT WORKSHOP ON CRACK GROWTH BEHAVIOR OF CONTINUOUS FIBER REINFORCED TITANIUM MATRIX COMPOSITES CY NOV, 1991 CL SAN DIEGO, CA SP AMER SOC TESTING & MAT, COMM MET MATRIX COMPOSITES DE COMPOSITE; METAL MATRIX; CONTINUOUS FIBER; FATIGUE; CRACK; SPACING AB In this study the extensive matrix fatigue cracking that has been observed in notched SCS-6/Ti-15-3 composites is investigated. Away from the notch a uniform spacing of the fatigue cracks develop. Closer to the notch, fiber-matrix debonding occurs, increasing distance between the cracks. Crack spacing predicted from cylinder models compare favorably with experimental observations. SEM fractography showed that the principal fatigue crack initiation occurred around the 0-degrees fibers. Primary fatigue cracking does not appear to be due to interface failure in the 90-degrees plies. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HILLBERRY, BM (reprint author), PURDUE UNIV,SCH MECH ENGN,W LAFAYETTE,IN 47907, USA. NR 10 TC 2 Z9 2 U1 0 U2 1 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD FAL PY 1993 VL 15 IS 3 BP 210 EP 216 PG 7 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA MA274 UT WOS:A1993MA27400005 ER PT J AU TELESMAN, J GHOSN, LJ KANTZOS, P AF TELESMAN, J GHOSN, LJ KANTZOS, P TI METHODOLOGY FOR PREDICTION OF FIBER BRIDGING EFFECTS IN COMPOSITES SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article; Proceedings Paper CT WORKSHOP ON CRACK GROWTH BEHAVIOR OF CONTINUOUS FIBER REINFORCED TITANIUM MATRIX COMPOSITES CY NOV, 1991 CL SAN DIEGO, CA SP AMER SOC TESTING & MAT, COMM MET MATRIX COMPOSITES DE COMPOSITES; CRACK PROPAGATION; FIBER BRIDGING; FIBER PRESSURE MODEL (FPM); METAL MATRIX COMPOSITES (MMCS); SHEAR LAG MODEL (SLM); SHEAR STRENGTH COEFFICIENT ID MATRIX CRACKING; MECHANICS AB A review of three different methods used at NASA Lewis to account for the effect of fiber bridging on fatigue crack growth (FCG) in metallic and intermetallic titanium-based composites is presented. Of the three methods, the fiber pressure model (FPM) was the only one able to accurately predict both crack opening displacements (CODs) and the FCG rates for both composites under the various applied loading conditions. Once the proper interfacial shear strength coefficient, tau, was selected, the shear lag model (SLM) resulted in accurate predictions of the crack opening profiles. While the SLM did account for a substantial decrease in the fatigue crack driving force due to the fiber bridging, it still overestimated the fatigue crack driving force, especially with an increase in the applied stress. It was hypothesized that the overestimation of the crack driving force by the SLM may be due to a higher tau near the crack tip than the rest of the crack wake. The higher tau in the crack tip region is thought to result from a limited amount of interfacial wear that the crack tip region experiences. The experimentally based approach for predicting FCG behavior accounted for a substantial portion of the fiber bridging effect; however, it also overestimated the resulting fatigue crack driving force. C1 OHIO AEROSP INST,CLEVELAND,OH 44142. RP TELESMAN, J (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL,CLEVELAND,OH 44135, USA. NR 18 TC 9 Z9 9 U1 0 U2 2 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD FAL PY 1993 VL 15 IS 3 BP 234 EP 241 PG 8 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA MA274 UT WOS:A1993MA27400008 ER PT J AU BAKUCKAS, JG JOHNSON, WS AF BAKUCKAS, JG JOHNSON, WS TI APPLICATION OF FIBER BRIDGING MODELS TO FATIGUE-CRACK GROWTH IN UNIDIRECTIONAL TITANIUM MATRIX COMPOSITES SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article; Proceedings Paper CT WORKSHOP ON CRACK GROWTH BEHAVIOR OF CONTINUOUS FIBER REINFORCED TITANIUM MATRIX COMPOSITES CY NOV, 1991 CL SAN DIEGO, CA SP AMER SOC TESTING & MAT, COMM MET MATRIX COMPOSITES DE MATRIX CRACKING; FIBER-MATRIX DEBONDING; MATRIX STRESS INTENSITY FACTOR; CONTINUUM FRACTURE MECHANICS; MICROMECHANICS; INTERFACIAL FRICTIONAL SHEAR STRESS; DISCRETE-CONTINUUM RELATIONS ID MECHANICAL-PROPERTIES; FRACTURE AB Several fiber bridging models were reviewed and applied in this research to study the matrix fatigue crack growth behavior in center notched [0]8 SCS-6/Ti-15-3 and [01, SCS-6/Ti-6Al-4V titanium matrix composites (TMCs). Observations revealed that fatigue damage consisted primarily of matrix cracks and fiber-matrix interfacial failure in the unidirectional TMC. Fiber-matrix interface failure included fracture of the brittle reaction zone and cracking between the two carbon-rich fiber coatings. Intact fibers in the wake of the matrix cracks reduce the stress intensity factor range. Thus, an applied stress intensity factor range (DELTAK(app) = DELTAS square-root pia) is inappropriate to characterize matrix crack growth behavior. Fiber bridging models were used to determine the matrix stress intensity factor range in the unidirectional TMC. In these models, the fibers in the wake of the crack are idealized as a closure pressure. An unknown constant frictional shear stress is assumed to act along the debond or slip length of the bridging fibers. In this study, the frictional shear stress was used as a curve fitting parameter to available data (crack growth data, crack opening displacement (COD) data, and debond length data). Large variations in the frictional shear stress required to fit the experimental data indicate that the fiber bridging models in their present form lack predictive capabilities. However, these models provide an efficient and relatively simple engineering method for conducting parametric studies of the matrix crack growth behavior based on constituent properties. RP BAKUCKAS, JG (reprint author), NASA,LANGLEY RES CTR,NATL RES COUNCIL,HAMPTON,VA 23681, USA. NR 30 TC 26 Z9 26 U1 0 U2 4 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD FAL PY 1993 VL 15 IS 3 BP 242 EP 255 PG 14 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA MA274 UT WOS:A1993MA27400009 ER PT J AU VENKATARAMAN, ST GULATI, S AF VENKATARAMAN, ST GULATI, S TI CONTROL OF NONLINEAR-SYSTEMS USING TERMINAL SLIDING MODES SO JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME LA English DT Note AB Many robotic systems would, in the future, be required to operate in environments that are highly unstructured and active, i.e., possessing means of self-actuation. Although a significant volume of results exist in model-based, robust and adaptive control literature, general issues pertinent to the performance of such control systems remain unresolved, e.g., feasibility of implementing high gain switches for control robustness. It is also pointed out that in certain applications, control switching can be very detrimental to the overall system. The primary focus of this paper is development of a new approach to control synthesis for robust robot operations in unstructured environments. To enhance control performance with full model information, we introduce the notion of terminal convergence, and develop control laws based upon a new class of sliding modes, denoted terminal sliders. We demonstrate that terminal sliders provide robustness to parametric uncertainty without having to resort to high frequency control switching, as in the case of conventional sliders [2]. In addition, stability analysis that is conducted to demonstrate terminal slider approach results in improved control performance and allows for simple robust design of control parameters. Further, improved (guaranteed) precision of terminal sliders is argued for through an analysis of steady state behavior. C1 JET PROP LAB,NEURAL COMPUTAT & NONLINEAR SCI GRP,PASADENA,CA 91109. RP VENKATARAMAN, ST (reprint author), JET PROP LAB,MACHINE INTELLIGENCE APPLICAT GRP,PASADENA,CA 91109, USA. NR 24 TC 35 Z9 38 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-0434 J9 J DYN SYST-T ASME JI J. Dyn. Syst. Meas. Control-Trans. ASME PD SEP PY 1993 VL 115 IS 3 BP 554 EP 560 DI 10.1115/1.2899138 PG 7 WC Automation & Control Systems; Instruments & Instrumentation SC Automation & Control Systems; Instruments & Instrumentation GA MA123 UT WOS:A1993MA12300035 ER PT J AU PICKERING, KD WIESNER, MR AF PICKERING, KD WIESNER, MR TI COST MODEL FOR LOW-PRESSURE MEMBRANE FILTRATION SO JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE LA English DT Article ID ULTRAFILTRATION; OPTIMIZATION; DESIGN AB A model for capital and operating costs of low-pressure membrane filtration is presented. The model is used to explore the impact of variables describing system operation and membrane characteristics on treatment costs as well as to compare the cost of treating raw waters of different qualities using nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF). The cost of UF or MF to remove particles from raw waters of moderate to high turbidity and concentrations of dissolved organic carbon (DOC) is calculated to be approximately twice that required to treat low-turbidity streams or ground waters. At small design capacities (2,000 m3/hr), UF and MF are calculated to be competitive or less expensive processes for liquid-solid separation in potable water treatment when compared with conventional filtration. MF and UF costs calculated tor small facilities (almost-equal-to 20 m3/hr) treating low-turbidity waters are comparable. For larger design capacities, UF may be less costly than MF. Treatment applications requiring significant removal of DOC and/or divalent ions may warrant the higher costs calculated for NF. C1 RICE UNIV,GEORGE R BROWN SCH ENGN,DEPT ENVIRONM SCI & ENGN,HOUSTON,TX 77251. RP PICKERING, KD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV TRAINING DG48,HOUSTON,TX 77058, USA. NR 31 TC 41 Z9 41 U1 1 U2 6 PU ASCE-AMER SOC CIVIL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0733-9372 J9 J ENVIRON ENG-ASCE JI J. Environ. Eng.-ASCE PD SEP-OCT PY 1993 VL 119 IS 5 BP 772 EP 797 DI 10.1061/(ASCE)0733-9372(1993)119:5(772) PG 26 WC Engineering, Environmental; Engineering, Civil; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA LY858 UT WOS:A1993LY85800003 ER PT J AU JONES, DR BRILL, RW BUSHNELL, PG AF JONES, DR BRILL, RW BUSHNELL, PG TI VENTRICULAR AND ARTERIAL DYNAMICS OF ANESTHETIZED AND SWIMMING TUNA SO JOURNAL OF EXPERIMENTAL BIOLOGY LA English DT Article ID TROUT SALMO-GAIRDNERI; THUNNUS-ALALUNGA; BLOOD-FLOW; KATSUWONUS-PELAMIS; OXYGEN-TRANSPORT; ALBACORE TUNA; RESPONSES; ALBACARES; DORSAL AB Cardiovascular dynamics of tuna have been investigated by recording blood pressures and flows in the central circulation of both anaesthetised and swimming individuals. In anaesthetised fish (N=5), heart rate averaged 112+/-21 beats min-1 (mean+/-S.E.) and stroke volume was 0.67+/-0.24 ml kg-1 when normoxic water flowed over the gills. Ventricular diastolic pressure was zero until atrial contraction filled the ventricle. Ventral aortic pressures were high (mean 12.08+/-1.15 kPa), and blood flow was continuous in the ventral aorta throughout diastole. Dorsal aortic pressure (mean 6.3+/-1.28 kPa; N=4) and flow were both pulsatile. Pressure pulsatility (pulse pressure as a proportion of mean pressure) was about one-quat-ter of flow pulsatility, indicating considerable compliance in the dorsal aortic circulation. Total peripheral resistance averaged 0.17+/-0.4 kPa ml-1 kg-1 min-1 of which gill resistance averaged 48+/-15 % (N=4). For the ventral aorta, impedance modulus fell markedly from the mean value and then declined more gradually towards zero with increasing harmonic frequencies. Impedance phase was negative (-0.8 to -1.1 rad) meaning that flow leads pressure at all harmonics. In swimming yellowfin tuna (N=5), heart rate averaged 108.8+/-12.1 beats min-1 and mean ventral and dorsal aortic pressures were 11.6+/-0.5 and 6.8+/-1.2 kPa, respectively, so gill resistance was 42% of total peripheral resistance. Average stroke volume in three swimming kawakawa was 0.54+/-0.2 ml kg-1 at a mean heart rate of 128+/-48 beats min-1. Data from swimming fish were within the range obtained from anaesthetised tuna. A simple model of the fish circulation consisting of two sets of compliant and resistive elements coupled in series (a second-order RC network) gave reasonable predictions of arterial pressure-flow relationships. Hence, we conclude that a 'Windkessel' dominates central cardiovascular dynamics of tuna despite heart rates and blood pressures that fall in the mammalian range. C1 UNIV BRITISH COLUMBIA,DEPT ZOOL,VANCOUVER V6T 1Z4,BC,CANADA. RP JONES, DR (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES CTR,HONOLULU LAB,HONOLULU,HI 96822, USA. NR 34 TC 31 Z9 32 U1 0 U2 4 PU COMPANY OF BIOLOGISTS LTD PI CAMBRIDGE PA BIDDER BUILDING CAMBRIDGE COMMERCIAL PARK COWLEY RD, CAMBRIDGE, CAMBS, ENGLAND CB4 4DL SN 0022-0949 J9 J EXP BIOL JI J. Exp. Biol. PD SEP PY 1993 VL 182 BP 97 EP 112 PG 16 WC Biology SC Life Sciences & Biomedicine - Other Topics GA LZ746 UT WOS:A1993LZ74600007 ER PT J AU GATSKI, TB SPEZIALE, CG AF GATSKI, TB SPEZIALE, CG TI ON EXPLICIT ALGEBRAIC STRESS MODELS FOR COMPLEX TURBULENT FLOWS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID REYNOLDS-STRESS; SHEAR FLOWS; EXPANSION AB Explicit algebraic stress models that are valid for three-dimensional turbulent flows in non-inertial frames are systematically derived from a hierarchy of second-order closure models. This represents a generalization of the model derived by Pope (1975) who based his analysis on the Launder, Reece & Rodi model restricted to two-dimensional turbulent flows in an inertial frame. The relationship between the new models and traditional algebraic stress models - as well as anisotropic eddy viscosity models - is theoretically established. A need for regularization is demonstrated in an effort to explain why traditional algebraic stress models have failed in complex flows. It is also shown that these explicit algebraic stress models can shed new light on what second-order closure models predict for the equilibrium states of homogeneous turbulent flows and can serve as a useful alternative in practical computations. RP GATSKI, TB (reprint author), NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23681, USA. NR 31 TC 439 Z9 454 U1 1 U2 12 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD SEP PY 1993 VL 254 BP 59 EP 78 DI 10.1017/S0022112093002034 PG 20 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA MA311 UT WOS:A1993MA31100004 ER PT J AU BRENTNER, KS AF BRENTNER, KS TI DIRECT NUMERICAL-CALCULATION OF ACOUSTICS - SOLUTION EVALUATION THROUGH ENERGY ANALYSIS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID FLOWS AB The propagation of acoustic energy from a sound source to the far field is a fundamental problem of acoustics. In this paper the use of computational fluid dynamics (CFD) to directly calculate the acoustic field is investigated. The two-dimensional, compressible, inviscid flow about an accelerating circular cylinder is used as a model problem. The time evolution of the energy transfer from the cylinder surface to the fluid, as the cylinder is moved from rest to some non-negligible velocity, is shown. Energy is the quantity of interest in the calculations since various components of energy have physical meaning. By examining the temporal and spatial characteristics of the numerical solution, a distinction can be made between the propagating acoustic energy, the convecting energy associated with the entropy change in the fluid, and the energy following the body. In the calculations, entropy generation is due to a combination of physical mechanisms and numerical error. In the case of propagating acoustic waves, entropy generation seems to be a measure of numerical damping associated with the discrete flow solver. RP BRENTNER, KS (reprint author), NASA,LANGLEY RES CTR,MS 461,HAMPTON,VA 23681, USA. NR 8 TC 5 Z9 5 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD SEP PY 1993 VL 254 BP 267 EP 281 DI 10.1017/S0022112093002125 PG 15 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA MA311 UT WOS:A1993MA31100013 ER PT J AU JACKSON, TL MACARAEG, MG HUSSAINI, MY AF JACKSON, TL MACARAEG, MG HUSSAINI, MY TI THE ROLE OF ACOUSTICS IN FLAME VORTEX INTERACTIONS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID ASYMPTOTIC ANALYSIS; NONUNIFORM MIXTURE; DIFFUSION FLAME; PREMIXED FLAMES; TRIPLE-FLAME; PROPAGATION; FIELD AB The role of acoustics in flame/vortex interactions is examined via asymptotic analysis and numerical simulation. The model consists of a one-step, irreversible Arrhenius reaction between initially unmixed species occupying adjacent half-planes which are allowed to mix and react by convection and diffusion in the presence of an acoustic field or a time-varying pressure field of small amplitude. The main emphasis is on the influence of the acoustics on the ignition time and flame structure as a function of vortex Reynolds number and initial temperature differences of the reactants. C1 NASA, LANGLEY RES CTR, INST COMP APPLICAT SCI & ENGN, HAMPTON, VA 23681 USA. RP JACKSON, TL (reprint author), OLD DOMINION UNIV, DEPT MATH & STAT, NORFOLK, VA 23529 USA. NR 39 TC 8 Z9 8 U1 0 U2 0 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 SEP PY 1993 VL 254 BP 579 EP 603 DI 10.1017/S0022112093002265 PG 25 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA MA311 UT WOS:A1993MA31100027 ER PT J AU BUSHNELL, DM AF BUSHNELL, DM TI UNITED-STATES COMPETITIVENESS - A FLUID ENGINEERS VIEWPOINT .4. WHAT GOVERNMENT STUDIES INDICATE AND SOME SUGGESTIONS SO JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Editorial Material RP BUSHNELL, DM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0098-2202 J9 J FLUID ENG-T ASME JI J. Fluids Eng.-Trans. ASME PD SEP PY 1993 VL 115 IS 3 BP 343 EP 344 DI 10.1115/1.2910147 PG 2 WC Engineering, Mechanical SC Engineering GA MA450 UT WOS:A1993MA45000003 ER PT J AU QUATTROCHI, DA AF QUATTROCHI, DA TI THE NEED FOR A LEXICON OF SCALE TERMS IN INTEGRATING REMOTE-SENSING DATA WITH GEOGRAPHIC INFORMATION-SYSTEMS SO JOURNAL OF GEOGRAPHY LA English DT Article DE SCALE; MULTIPLE SCALING; REMOTE SENSING; IGIS ID GIS AB The concept of scale is fundamental to geography, yet the definitions for ''scale'' and related spatial terms can be confusing to those working in other spatial science disciplines. This is particularly true in the emerging multidisciplinary world of integrated remote sensing and geographic information systems, or IGIS's, where data of different types and at various spatial and temporal scales are combined to support complex space-time data analyses. Without a basic lexicon of accepted scale terms, working within an IGIS can breed confusion in the interpretation of data and the models that result from an IGIS construct. This paper provides some terminologies of scale that can be used as a framework for a multidisciplinary lexicon of accepted scaling terms and describes their relationships to an IGIS. It also illustrates how scaling terms can be potentially misunderstood when applied to geographic techniques that are used in disciplines related to geography. C1 NASA,SCI & TECHNOL LAB,BAY ST LOUIS,MS. RP QUATTROCHI, DA (reprint author), NASA,MARSHALL SPACE FLIGHT CTR,DIV EARTH SCI & APPLICAT,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 25 TC 5 Z9 5 U1 1 U2 2 PU NATL COUNCIL GEOGRAPHIC EDUCATION PI INDIANA PA INDIANA UNIV PENNSYLVANIA, INDIANA, PA 15705 SN 0022-1341 J9 J GEOGR JI J. Geogr. PD SEP-OCT PY 1993 VL 92 IS 5 BP 206 EP 212 DI 10.1080/00221349308979654 PG 7 WC Geography SC Geography GA ML684 UT WOS:A1993ML68400001 ER PT J AU OBERBECK, VR MARSHALL, JR AGGARWAL, H AF OBERBECK, VR MARSHALL, JR AGGARWAL, H TI IMPACTS, TILLITES, AND THE BREAKUP OF GONDWANALAND - REPLY SO JOURNAL OF GEOLOGY LA English DT Note RP OBERBECK, VR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 16 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0022-1376 J9 J GEOL JI J. Geol. PD SEP PY 1993 VL 101 IS 5 BP 679 EP 683 PG 5 WC Geology SC Geology GA LX142 UT WOS:A1993LX14200013 ER PT J AU PESSES, ME JONES, WV FORMAN, M AF PESSES, ME JONES, WV FORMAN, M TI VOYAGER AND PIONEER MISSIONS TO THE BOUNDARIES OF THE HELIOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY RADIO EMISSIONS; SOLAR-WIND; ANOMALOUS COMPONENT; OUTER HELIOSPHERE; COSMIC-RAYS; SHOCK; ACCELERATION; MODULATION; HELIOPAUSE; TRANSPORT AB The interaction of the solar wind with the interstellar medium is expected to result in a complex, probably dynamic outer heliospheric boundary region. In increasing distance from the Sun the boundary region includes the solar wind termination shock, the heliopause, and perhaps a heliobow-shock. The continuing missions of Voyager 1 and 2 and Pioneer 10 and 11 provide a unique opportunity to make in situ particle and field observations of the boundaries of the heliosphere and associated phenomena. Observations already made by these spacecraft suggest that the termination shock may be located 60-100 AU from the Sun. Voyager 1 will reach 60 AU in 1995 and 100 AU in 2006. NASA's Space Physics Division is planning with the Voyager and Pioneer Projects to ensure timely and maximum scientific return from spacecraft encounters with the solar wind termination region. Initial emphasis is on being able to reliably determine when an encounter is imminent, so that spacecraft tracking and spacecraft and instrument configurations can be changed to encounter modes. It is anticipated that multiple encounters with heliospheric boundaries will occur due to motion of the boundaries in response to large variations in the solar wind pressure. C1 NASA HEADQUARTERS,DIV SPACE PHYS,WASHINGTON,DC 20546. RP PESSES, ME (reprint author), SCI APPLICAT INT CORP,400 VIRGINIA AVE SW,SUITE 810,WASHINGTON,DC 20024, USA. NR 34 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15123 EP 15127 DI 10.1029/93JA01174 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300002 ER PT J AU BARNES, A AF BARNES, A TI MOTION OF THE HELIOSPHERIC TERMINATION SHOCK - A GAS-DYNAMIC MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; INTERSTELLAR-MEDIUM AB The heliospheric termination shock is expected to move in response to variation in upstream solar wind conditions; we present a simple quantitative model of this motion. In the model it is assumed that the termination shock is initially a strong gas dynamic shock at rest with respect to the Sun and that upstream of the shock there is a discontinuous increase or decrease in dynamical pressure. This jump is taken to be a contact discontinuity, i.e., an increase (decrease) in density without change in speed at the discontinuity. We then analyze what happens after the discontinuity encounters the shock. The postinteraction configuration is a moving termination shock, a postshock contact discontinuity, and a compression or rarefaction signal propagating into the downstream medium. The analysis is also extended to consider the successive passage of contact discontinuities through the termination shock. On the basis of this model we suggest that the termination shock is constantly in motion and that the following picture emerges: (1) the mean position of the shock is near the mean equilibrium position corresponding to balance between mean solar wind dynamical pressure and mean interstellar pressure; but (2) the shock makes inward and outward excursions over several (or even several tens?) astronomical units and at any given moment its position is determined by the recent (past several month) history of variations of solar wind dynamical pressure, The inward or outward speed of the shock depends on the magnitude of the change in upstream dynamical pressure but is typically of the order of 100 km/s. Therefore the first detection of this shock would be due to the shock moving inward through the spacecraft location rather than the spacecraft reaching a fixed shock location. A kinematic analysis due to Suess (this issue) leads to generally similar conclusions, although his conjecture that the speed of the termination shock may be much larger for outward motion than for inward motion is not supported by our dynamical analysis. RP BARNES, A (reprint author), NASA,THEORET STUDIES BRANCH,MOFFETT FIELD,CA 94035, USA. NR 18 TC 67 Z9 67 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15137 EP 15146 DI 10.1029/92JA02895 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300004 ER PT J AU SUESS, ST AF SUESS, ST TI TEMPORAL VARIATIONS IN THE TERMINATION SHOCK DISTANCE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND AB A kinematic analysis is made of solar wind driven temporal variations in the heliospheric termination shock distance. This has become possible because the large-scale dynamics of, and temporal variations in the distant solar wind are now well enough known from a combination of in situ and remote measurements. Conversely, nothing is known of the corresponding properties in the local interstellar medium, and hence these will be ignored. Given specific assumptions for how the termination shock responds to solar wind fluctuations, it is shown that the termination shock is very agile, moving in and out by up to a few AU in a month. This conclusion holds for a broad range of shock response assumptions. Because a spacecraft moves slowly in comparison to the termination shock, the shock will sweep back and forth over the spacecraft once the shock is first encountered. RP SUESS, ST (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 19 TC 57 Z9 57 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15147 EP 15155 DI 10.1029/93JA01170 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300005 ER PT J AU NERNEY, S SUESS, ST SCHMAHL, EJ AF NERNEY, S SUESS, ST SCHMAHL, EJ TI FLOW DOWNSTREAM OF THE HELIOSPHERIC TERMINAL SHOCK - THE MAGNETIC-FIELD ON THE HELIOPAUSE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article AB Modeling the kinematic magnetic field in the solar wind beyond the terminal shock shows that a ridge of magnetic pressure is produced just inside the heliopause. This ridge has its maximum amplitude in the plane defined by the solar rotation axis and the heliotail and decreases to zero amplitude in the solar equatorial plane. The ridge is sufficiently large that it will cause the layer immediately inside the heliopause to thicken, pushing the heliopause outward and slightly affecting its position relative to the terminal shock. However, the ridge is far too thin to cause an important change in the distance of the terminal shock from the Sun. The kinematic assumption prevents us from estimating the actual magnitude of the ridge, but we show that these conclusions are a simple consequence of geometrical arguments for incompressible, steady, laminar flows. Moreover, the heliopause magnetic field originates on the terminal shock near the substagnation point. Consequently, the heliospheric current sheet field reversals are painted onto the inside surface of the heliopause. Alternate magnetic polarity strips will be oppositely directed relative to the interstellar magnetic field, implying that reconnection inevitably occurs on a fine scale near the nose of the heliosphere. This suggests that the heliopause is a leaky, diffuse surface. C1 UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP NERNEY, S (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES52,HUNTSVILLE,AL 35812, USA. NR 18 TC 44 Z9 44 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15169 EP 15176 DI 10.1029/93JA01177 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300008 ER PT J AU LIEWER, PC GOLDSTEIN, BE OMIDI, N AF LIEWER, PC GOLDSTEIN, BE OMIDI, N TI HYBRID SIMULATIONS OF THE EFFECTS OF INTERSTELLAR PICKUP HYDROGEN ON THE SOLAR-WIND TERMINATION SHOCK SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COMETARY BOW SHOCKS; ANOMALOUS COMPONENT; COSMIC-RAYS; UP IONS; ACCELERATION AB Hybrid (kinetic ions/fluid electrons) plasma simulations are used to study the effects of a population of energetic interstellar pickup hydrogen ions on the solar wind termination shock. The pickup hydrogen is treated as a second ion species in the simulations, and thus the effects of the pick-ups on the shock, as well as the effects of the shock on the pickups. are treated in a fully self-consistent manner. For quasi-perpendicular shocks with 10-20% pickup hydrogen the pickup ions manifest themselves in a small foot ahead of the shock ramp caused by pickup ion reflection. For oblique shocks with smaller angles between the field and the shock normal (theta(Bn) almost-equal-to 40-degrees-60-degrees) a large fraction of the pickup ions are reflected and move back upstream where they excite large amplitude magnetosonic waves which steepen into shocklets. These backstreaming pickup ions may provide advance warning of a spacecraft encounter with the termination shock. C1 UNIV CALIF SAN DIEGO,CALIFORNIA SPACE INST,DEPT ELECT & COMP ENGN,LA JOLLA,CA 92093. RP LIEWER, PC (reprint author), JET PROP LAB,MS 169-506,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 20 TC 73 Z9 73 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15211 EP 15220 DI 10.1029/93JA01172 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300013 ER PT J AU WHANG, YC BURLAGA, LF AF WHANG, YC BURLAGA, LF TI TERMINATION SHOCK - SOLAR-CYCLE VARIATIONS OF LOCATION AND SPEED SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID WIND PROTON TEMPERATURE; PIONEER-10; PLASMA AB Plasma and magnetic field data from Voyagers 1 and 2 over an 11-year period (1978-1988) together with a one-fluid MHD model are used to study the motion of the termination shock. The observed large fluctuations in solar wind parameters cause variations in the speed, in the jump conditions, and in the location of the termination shock. If the interstellar stagnation pressure is equivalent to a magnetic field of 0.5 nT plus draping enhancements, the termination shock moves between 88 AU and 102 AU. The location of the termination shock is anticorrelated with the sunspot number. The solar cycle variation appears to be the basic variation for the position of the termination shock. In the declining phase of the solar cycle, the solar wind has relatively large momentum and the shock moves outward. Near solar minimum the shock reaches its maximum distance. In the rising phase of the solar cycle, the shock moves inward as the shock speed is negative. Due to uncertainty of the interstellar conditions it is difficult to predict accurately the position of the termination shock. However, the anticorrelation between the shock distance and the sunspot number remains unchanged independent of the average distance of the termination shock. The termination shock is very strong with pressure ratios of a few thousands, the fast Mach number is approximately 12, and the plasma beta ratio jumps from approximately 0.1 to approximately 14. During the declining phase of the solar cycle, the shock speed is often great.er than or comparable to the spacecraft speed. If the crossing of the termination shock by a spacecraft occurs during the declining phase, the spacecraft will cross the termination shock 3 or more times over a period of about 4 years. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP WHANG, YC (reprint author), CATHOLIC UNIV AMER,DEPT MECH ENGN,WASHINGTON,DC 20064, USA. NR 24 TC 52 Z9 52 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15221 EP 15230 DI 10.1029/93JA01472 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300014 ER PT J AU SRIVASTAVA, KM TSURUTANI, BT GOLDSTEIN, BE SHARMA, V AF SRIVASTAVA, KM TSURUTANI, BT GOLDSTEIN, BE SHARMA, V TI STABILITY OF THE HALLEY COMETOSHEATH WITH RESISTIVITY AND PLASMA MOTION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID TOLLMIEN-SCHLICHTING WAVES; COMET HALLEY; BOUNDARY-LAYERS; STREAMWISE VORTICES; IONOPAUSE; CAVITY AB The MHD stability of the cometary inner sheath determined by the balance between the inward Lorentz body force and the outward ion-neutral drag force is investigated by numerically solving the wave equations which include resistivity, plasma motion and plasma pressure with the help of two-point boundary value method. The eigenvalues and the eigenfunctions are obtained numerically by treating the cometary inner sheath as a layer of finite thickness, bounded by the contact surface, that is, the diamagnetic cavity boundary. To gain an insight into the problem, certain limiting cases of the wave equations are also discussed. The diamagnetic cavity boundary and the adjacent layer of about 100-km thickness of comet Halley is found to be unstable. The effects of finite plasma pressure, dissociative recombination, mass loading due to photoionization, resistivity, and plasma motion am found to be stablizing but are unable to quench the instability completely. An estimate of tau(C)/tau(i) shows that it hes in the range of 10 to 20 or even higher which appears to be sufficient for the effective penetration of the magnetic field perturbations into the cavity surface. Motion of the Halley ionopause has been confirmed by observations: according to Neubauer (1987), Halley ionopause seemed to have strong ripples with a wavelength of several hundred kilometers. C1 DEPT DEF RES DEV,INST SYST STUDIES & ANALYSES,DELHI 110054,INDIA. RP SRIVASTAVA, KM (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 25 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15263 EP 15273 DI 10.1029/93JA00761 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300018 ER PT J AU RICHARDSON, IG CANE, HV AF RICHARDSON, IG CANE, HV TI SIGNATURES OF SHOCK DRIVERS IN THE SOLAR-WIND AND THEIR DEPENDENCE ON THE SOLAR SOURCE LOCATION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; MAGNETIC-FIELD STRUCTURE; INTERPLANETARY SHOCKS; ENERGETIC PARTICLES; LOOP STRUCTURE; EVENTS; CLOUDS; EVOLUTION; 1-AU AB Solar wind and energetic ion observations following 40 interplanetary shocks with well-established solar source locations have been examined in order to determine whether signatures characteristic of the coronal material forming the shock driver are present. The signatures considered include magnetic-field-aligned bidirectional ion flows observed by the ISEE 3 and IMP 8 spacecraft: bidirectional solar wind electron heat fluxes: solar wind plasma proton and electron temperature depressions; low-beta plasma; enhanced, low-variance magnetic fields: and energetic ion depressions. Several shock driver signatures are commonly observed following shocks originating from within approximately 50-degrees of central meridian and are generally absent for other events. We conclude that shock drivers generally extend up to approximately 100-degrees in longitude. centered on the solar source longitude. A particular shock driver signature is typically found following approximately 80% of shocks from near-central meridian events. However, only approximately 20% of shocks from near-central meridian events are associated with the bidirectional 35-1000 keV ion events discussed by Marsden et al. (1987). Since shocks from central meridian events are not usually associated with all the shock driver signatures examined, the absence of a driver cannot be confirmed from consideration of one of these signatures alone. We also find evidence that a few bidirectional energetic ion and solar wind electron heat flux events following shocks (in particular from far eastern sources) may occur on open field lines outside of shock drivers. RP RICHARDSON, IG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. OI Richardson, Ian/0000-0002-3855-3634 NR 47 TC 88 Z9 89 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15295 EP 15304 DI 10.1029/93JA01466 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300021 ER PT J AU OSHEROVICH, VA FARRUGIA, CJ BURLAGA, LF LEPPING, RP FAINBERG, J STONE, RG AF OSHEROVICH, VA FARRUGIA, CJ BURLAGA, LF LEPPING, RP FAINBERG, J STONE, RG TI POLYTROPIC RELATIONSHIP IN INTERPLANETARY MAGNETIC CLOUDS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA SHEET; SOLAR-WIND; INDEX; CONVECTION; VOYAGER; 1-AU AB Interplanetary magnetic clouds are expanding MHD configurations characterized by strong magnetic fields, large rotations of the field vector, and low ion temperatures. In this paper we present high time resolution data from the ISEE 3 and IMP 8 spacecraft on the magnetic field and the proton and electron populations in a number of magnetic clouds. Our objective is to study aspects of the thermodynamics of magnetic clouds and the relation between their thermodynamic and magnetic structures. Our analysis suggests the following features of the thermodynamics of magnetic clouds: (1) The electron and ion populations are not in thermal equilibrium with each other, the electron temperature, T(e), being in general up to an order of magnitude higher than the proton temperature, T(p). The temperature ratio T(e)/T(p) in these magnetic clouds is larger than typical values of this quantity in the solar wind at comparable heliocentric distances. (2) For the proton component we find that a polytropic law with gamma(p) in the range 1.1 < gamma(p) < 1.3 is probably adequate to describe the relation between T(p) and density. (3) For the electrons (E < 1.18 keV) the energetics are likewise governed by a polytropic law. Unlike the protons the polytrope that describes the electrons has an index that is less than unity, implying anticorrelation between T(e) and the number density. For the two clouds analyzed where electron data are available, gamma(e) almost-equal-to 0.48 +/- 0.2. (4) As a corollary of case 3, the variation of T(e) with density in magnetic clouds is the reverse of that generally found in the inner heliosphere. (5) Electron temperatures are well correlated with the magnetic field strength, the highest values being reached where the field strength maximizes. We interpret these experimental findings along the following lines. While the magnetic field of the cloud expands, the ions are cooled (though not so effectively as in the adiabatic case (gamma(ad) = 5/3), indicating some exchange of energy with the ambient solar wind). In contrast, since gamma(e) < 1, when the density drops as a result of expansion, T(e) increases and, consequently, a temperature difference develops between the two species. The hot electrons are trapped by the magnetic field in the core of the magnetic cloud. If magnetic clouds originate in the region near the Sun where T(p) < T(e), the subsequent expansion accentuates this temperature disparity further. Such conditions are favorable for the generation of ion acoustic waves. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP OSHEROVICH, VA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 40 TC 62 Z9 65 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15331 EP 15342 DI 10.1029/93JA01012 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300024 ER PT J AU PEREDO, M STERN, DP TSYGANENKO, NA AF PEREDO, M STERN, DP TSYGANENKO, NA TI ARE EXISTING MAGNETOSPHERIC MODELS EXCESSIVELY STRETCHED SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD MODEL; NEUTRAL SHEET; EQUATORIAL MAGNETOTAIL; QUANTITATIVE MODELS; GEOMAGNETIC-FIELD; TAIL; POSITION; SHAPE AB The distribution of the average north-south magnetic field component [B(z)] in the vicinity of the neutral sheet has been investigated. This component is crucial for mappings between the nightside polar ionosphere and the equatorial magnetosphere. Data sets consisting of approximately 0.5 R(E) averages of magnetic field observations by the IMP/HEOS and ISEE spacecraft have been compared to the field predicted by the Tsyganenko models T87 and T89. In agreement with recent studies by C. Huang (data with 4-s resolution), it was found that both T87 and T89 underestimate [B(z)] in the near tail region (x(GSM) = -10 to -22 R(E)) by as much as a factor of 2. Modified versions of the T87 model, incorporating plasma sheet warping, were obtained by fitting the model parameters via nonlinear least squares to the ISEE data set and yielded [B(z)] values in agreement with the ISEE data. The study reveals an enormous scatter among the observed baseline values of [B(z)] (on a time scale of 10-20 min), as well as intrinsic biases imposed by the mathematical structure of tail models. and these two factors (especially the first one) greatly limit the accuracy of model predictions of tail [B(z)]. In order to reduce the second factor, a localized tail model has been developed and was used to explore the spatial variations of [B(z)]. Comparisons between observations and models, both global and local, are presented. Finally, suggested guidelines for use of existing models and limitations of their use are discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP PEREDO, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Tsyganenko, Nikolai/J-7377-2012 OI Tsyganenko, Nikolai/0000-0002-5938-1579 NR 26 TC 80 Z9 80 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15343 EP 15354 DI 10.1029/93JA01150 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300025 ER PT J AU ZHANG, X COMFORT, RH MUSIELAK, ZE MOORE, TE GALLAGHER, DL GREEN, JL AF ZHANG, X COMFORT, RH MUSIELAK, ZE MOORE, TE GALLAGHER, DL GREEN, JL TI PROPAGATION CHARACTERISTICS OF PC-3 COMPRESSIONAL WAVES GENERATED AT THE DAYSIDE MAGNETOPAUSE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; MAGNETIC PULSATIONS; ELECTRON-DENSITY; EARTHS MAGNETOSPHERE; ULF FLUCTUATIONS; 3-4 PULSATIONS; MAGNETOSHEATH; FIELD AB New, three-dimensional ray tracing of Pc 3 compressional waves from the magnetosheath reveals that the magnetosphere can present a major propagation barrier to the penetration of these waves to the plasmasphere. This barrier is the ion-ion cutoff between the He+ and O+ gyroresonances. As a result of the frequency-dependent location of this cutoff, the magnetosphere behaves like a filter for Pc 3 compressional waves, and only low-frequency components of Pc 3 compressional waves can penetrate to inner magnetosphere. Results are in agreement with previous satellite observations. This ''filter action'' strongly depends on the relative concentration of He+ and O+ and is therefore sensitive to solar and magnetic activity. Ray-tracing results are based on a cold plasma dispersion relation, a semi-empirical model of plasma density, and the Mead-Fairfield magnetic field model. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. NASA,GODDARD SPACE FLIGHT CTR,NATL SPACE SCI DATA CTR,GREENBELT,MD 20771. RP ZHANG, X (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERON,HUNTSVILLE,AL 35899, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 43 TC 9 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15403 EP 15410 DI 10.1029/93JA01322 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300030 ER PT J AU SLAVIN, JA SMITH, MF MAZUR, EL BAKER, DN HONES, EW IYEMORI, T GREENSTADT, EW AF SLAVIN, JA SMITH, MF MAZUR, EL BAKER, DN HONES, EW IYEMORI, T GREENSTADT, EW TI ISEE-3 OBSERVATIONS OF TRAVELING COMPRESSION REGIONS IN THE EARTHS MAGNETOTAIL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DEEP GEOMAGNETIC TAIL; DISTANT MAGNETOTAIL; PLASMA SHEET; MAGNETIC-FIELD; NEAR-EARTH; MAGNETOSPHERIC SUBSTORMS; BOUNDARY-LAYER; RECONNECTION; SIMULATION; EXPANSION AB A traveling compression region (TCR) is a several-minute long compression of the lobe magnetic field produced by a plasmoid as it moves down the tail. They are generally followed by a longer interval of southward tilting magnetic fields. This study reports the first comprehensive survey of TCRs in the distant magnetotail. A total of 116 TCRs were identified in the ISEE 3 magnetic field observations. Of this population, 37 TCRs were observed to be separated by 30 min or more from any other TCR and are termed ''isolated'' events. ''Paired'' events are defined as two TCRs separated by less than 30 min. There were 36 such TCRs corresponding to 18 paired events. ''Multiple'' events were also observed in which more than two TCRs occurred in a series without a gap between TCRs of more than 30 min. The 11 multiple events identified in this study had an average of about four traveling compression regions each for a total of 43 TCRs. The mean amplitude, DELTAB/B, and duration, DELTAT, for all TCRs were found to be 7.6% and 158 s, respectively. TCRs occurring as isolated events were the largest (DELTAB/B = 8.8% and DELTAT = 218 s) and those associated with multiple events were the smallest (DELTAB/B = 5.6% and DELTAT = 84 s). The mean duration of the period of southward tilting B(z) following isolated TCRs was 12.3 min. This time interval was found to be quite similar to the average spacing between TCRs in paired and multiple events, 11.2 and 10.2 min, respectively. TCR amplitude and duration were found to be independent of location within the tail lobes suggesting that the plasmoids which cause the TCRs maintain approximately constant volume and shape as they move down the tail. Mean plasmoid dimensions estimated from TCR duration and amplitude under the assumption of a quasi-rigid magnetopause are 35 R(E) (length) x 15 R(E) (width) x 15 R(E) (height). Utilizing auroral kilometric radiation, the AL index, Pi 2 pulsations at two ground stations, and energetic particle data from three geosynchronous spacecraft. it is found that over 91% of the TCR events identified in this study followed substorm onsets or intensifications. The number of TCR events identified in this study are consistent with their release in association with a new substorm onset every 4-6 hrs. The results of this study strongly suggest that the release of plasmoids down the tail near the time of expansion phase onset is an integral step in the substorm process and an important element in the substorm energy budget. C1 HUGHES STX INC,LANHAM,MD. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. KYOTO UNIV,FAC SCI,DATA ANAL CTR GEOMAGNET & SPACE MAGNET,KYOTO 606,JAPAN. TRW CO INC,DEPT SPACE SCI,REDONDO BEACH,CA 90278. RP SLAVIN, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 51 TC 136 Z9 137 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15425 EP 15446 DI 10.1029/93JA01467 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300033 ER PT J AU FARRUGIA, CJ RICHARDSON, IG BURLAGA, LF LEPPING, RP OSHEROVICH, VA AF FARRUGIA, CJ RICHARDSON, IG BURLAGA, LF LEPPING, RP OSHEROVICH, VA TI SIMULTANEOUS OBSERVATIONS OF SOLAR MEV PARTICLES IN A MAGNETIC CLOUD AND IN THE EARTHS NORTHERN TAIL LOBE - IMPLICATIONS FOR THE GLOBAL FIELD LINE TOPOLOGY OF MAGNETIC CLOUDS AND FOR THE ENTRY OF SOLAR PARTICLES INTO THE MAGNETOSPHERE DURING CLOUD PASSAGE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ENERGETIC PARTICLES; EVENTS; SHOCK; LOOP AB We present simultaneous observations of magnetic fields and flow anisotropies of solar energetic (several MeV) protons and electrons made by the ISEE 3 and IMP 8 spacecraft during the passage of an interplanetary magnetic cloud on February 16 - 17, 1980. ISEE 3 was situated approximately 250 R(E) upstream of Earth at the L1 libration point, and IMP 8 was crossing the Earth's northern tail lobe and magnetosheath in an dusk-dawn direction at a mean downtail distance of approximately 27 R(E). Several solar particle onsets were seen at ISEE 3 during cloud passage, with corresponding energetic particle signatures being observed in the geomagnetic tail by IMP 8. Various differences in the particle signatures at the two spacecraft occur, however, and these may be interpreted in terms of the magnetic field line topology of the cloud, the connectivity of the cloud field lines to the solar surface, and the interconnection between the magnetic fields of magnetic cloud and of the Earth. The observations are consistent with a model of magnetic clouds according to which these mesoscale configurations are curved magnetic flux ropes attached at both ''ends'' to the Sun's surface and extending to 1 AU. The energetic particles stream out of the Sun along the cloud's helical field lines, arrive with appropriate time delays at an observation site inside the cloud, and become counterstreaming after mirroring within the cloud. When the field is the magnetic cloud had a persistent southward component, we can directly confirm the interconnection between the terrestrial and the cloud magnetic fields at the location of IMP 8 in the magnetotail. While at ISEE 3 inside the magnetic cloud the energetic particles have a strong east-west bidirectional flow, IMP 8 observes a tail-aligned bidirectional flow (i.e., roughly orthogonal to the flow direction at ISEE 3) as the energetic particles travel earthward along lobe field lines closer to Earth. Thus we have a case of solar particles gaining access into the magnetosphere at low altitudes first through magnetic connection of the magnetic cloud to the Sun and, subsequently, via the interconnections of the cloud's field lines to those of the Earth. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP FARRUGIA, CJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 31 TC 37 Z9 39 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15497 EP 15507 DI 10.1029/93JA01462 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300038 ER PT J AU GHOSH, S VINAS, AF GOLDSTEIN, ML AF GHOSH, S VINAS, AF GOLDSTEIN, ML TI PARAMETRIC-INSTABILITIES OF A LARGE-AMPLITUDE CIRCULARLY-POLARIZED ALFVEN-WAVE - LINEAR GROWTH IN 2-DIMENSIONAL GEOMETRIES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MODULATIONAL INSTABILITY; FILAMENTATION INSTABILITY; MAGNETIC-FIELD; EXCITATION; UPSTREAM; PARALLEL; DAUGHTER AB The growth of parametric instabilities, which may lead to the development of a turbulent cascade, is studied using a magnetohydrodynamic (MHD) code that permits nonlinear couplings in the parallel direction to the ambient magnetic field and one perpendicular direction. Compressibility is included in the form of a polytropic equation of state. Parametric instabilities associated with a parallel-propagating decay instability are found to dominate the low-beta case. An obliquely propagating filamentationlike instability dominates the high-beta case. The nonlinear growth of the nth harmonic of a daughter wave growing as a factor of n times the fundamental's growth rate is found in both cases. Nonlinear saturation is caused by the parallel decay instability in the low-beta case and by the oblique filamentationlike instability in the high-beta case. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP GHOSH, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 31 TC 35 Z9 35 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15561 EP 15570 DI 10.1029/93JA01534 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300044 ER PT J AU MILLER, NJ GREBOWSKY, JM HEDIN, AE SPENCER, NW AF MILLER, NJ GREBOWSKY, JM HEDIN, AE SPENCER, NW TI EQUATORIAL ION COMPOSITION, 140-200 KM, BASED ON ATMOSPHERE EXPLORER-E DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GENERAL-CIRCULATION MODEL; LOWER IONOSPHERE; ELECTRIC-FIELDS; PLASMA BUBBLES; REGION; THERMOSPHERE; ARECIBO; IRREGULARITIES; MIDLATITUDES; TEMPERATURE AB We have used in situ measurements of ion composition and horizontal winds, taken from equatorial orbiting Atmosphere Explorer E in eccentric orbit during 1975-1976 to investigate the bottomside ionosphere at altitudes 140-200 km. Representative daytime altitude profiles of ionization were stable against wide variations in horizontal wind patterns. On the nightside, ionization profiles displayed much structure, some of which was associated with variations in the horizontal winds. Special features that sometimes appeared in the structured nightside ionization were apparent ion composition waves, intermediate layers of enhanced ionization, and ionization depletions similar to equatorial ionization bubbles. Apparent ion composition waves displayed a horizontal wave length approximately 650 km. A series of measurements displayed enhanced layers of ionization that appeared to be newly separated from the bottomside midnight F layer. Ions detected in the enhanced ionization layers were primarily NO+ and O2+ without significant densities of metallic ions, an indication that metallic ions are not required to produce the layers at altitudes above 140 km. Equatorial ionization depletions were observed at lower altitudes than previously reported and displayed molecular ion depletions as well as O+ depletions. C1 UNIV RES FDN,GREENBELT,MD 20770. RP MILLER, NJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 914,GREENBELT,MD 20771, USA. RI Grebowsky, Joseph/I-7185-2013 NR 43 TC 16 Z9 16 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1993 VL 98 IS A9 BP 15685 EP 15692 DI 10.1029/93JA01147 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW353 UT WOS:A1993LW35300054 ER PT J AU JAIN, A RODRIGUEZ, G AF JAIN, A RODRIGUEZ, G TI RECURSIVE DYNAMICS ALGORITHM FOR MULTIBODY SYSTEMS WITH PRESCRIBED MOTION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SPATIAL OPERATOR ALGEBRA; FORMULATION AB This paper uses spatial operator techniques to develop a new algorithm for the dynamics of multibody systems with hinges undergoing prescribed motion. This algorithm is spatially recursive, and its computational complexity grows only linearly with the number of degrees of freedom in the system. Its structure is a hybrid of known recursive forward and inverse dynamics algorithms for regular multibody systems. Changes to the prescribed/nonprescribed nature of hinges can be implemented during run time since they are handled with very low overhead in the algorithm. RP JAIN, A (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 11 TC 6 Z9 7 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1993 VL 16 IS 5 BP 830 EP 837 DI 10.2514/3.21089 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LW547 UT WOS:A1993LW54700003 ER PT J AU KURDILA, AJ MENON, RG SUNKEL, JW AF KURDILA, AJ MENON, RG SUNKEL, JW TI NONRECURSIVE ORDER-N FORMULATION OF MULTIBODY DYNAMICS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SYSTEMS AB Although excellent progress has been made in deriving algorithms that are efficient for certain combinations of system topologies and concurrent multiprocessing hardware, several issues must be resolved to incorporate transient simulation in the control design process for large space structures. Specifically, strategies must be developed that are applicable to systems with numerous degreees of freedom. Algorithms are required that induce parallelism on a fine scale, suitable for the emerging class of highly parallel processors. This paper addresses these problems by employing the range space formulation of multibody dynamics and solving for multipliers using the preconditioned conjugate gradient method. By employing regular ordering of the system connectivity graph, an extremely efficient preconditioner can be derived from the range space metric. The method can achieve performance rates that depend linearly on the number of substructures. Furthermore, the approach is promising as a potential parallel processing algorithm in that it exhibits fine parallel granularity, is nonassembling, and is easily load balanced among processors without relying an system topology to induce parallelism. C1 NASA,LYNDON B JOHNSON SPACE CTR,DIV NAVIGAT CONTROL & AERONAUT,HOUSTON,TX 77058. RP KURDILA, AJ (reprint author), TEXAS A&M UNIV SYST,DEPT AEROSP ENGN,COLL STN,TX 77843, USA. NR 21 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1993 VL 16 IS 5 BP 838 EP 844 DI 10.2514/3.21090 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LW547 UT WOS:A1993LW54700004 ER PT J AU JUANG, JN WU, SC PHAN, M LONGMAN, RW AF JUANG, JN WU, SC PHAN, M LONGMAN, RW TI PASSIVE DYNAMIC CONTROLLERS FOR NONLINEAR MECHANICAL SYSTEMS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ROBUST AB A methodology for model-independent controller design for controlling the large angular motion of multibody dynamic systems is outlined. The controlled system may consist of rigid and flexible components that undergo large rigid body motion and small elastic deformations. Control forces/torques are applied to drive the system and at the same time suppress the vibrations due to flexibility of the components. The proposed controller consists of passive second-order systems that may be designed with little knowledge of the system parameters, even if the controlled system is nonlinear. Under other general assumptions, the passive design assures that the closed-loop system has guaranteed stability properties. Unlike positive real controller design, stabilization can be accomplished without direct velocity feedback. In addition, the second-order passive design allows dynamic feedback controllers with considerable freedom to tune for desired system response and to avoid actuator saturation. After developing the basic mathematical formulation of the design methodology, simulation results are presented to illustrate the proposed approach applied to a flexible six-degree-of-freedom manipulator. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA. RP JUANG, JN (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 13 TC 10 Z9 10 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1993 VL 16 IS 5 BP 845 EP 851 DI 10.2514/3.21091 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LW547 UT WOS:A1993LW54700005 ER PT J AU PAPPA, RS ELLIOTT, KB AF PAPPA, RS ELLIOTT, KB TI CONSISTENT-MODE INDICATOR FOR THE EIGENSYSTEM REALIZATION-ALGORITHM SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID IDENTIFICATION AB A new method is described for assessing the consistency of structural modal parameters identified with the eigensystem realization algorithm. Identification results show varying consistency in practice due to many sources including high modal density, nonlinearity, and inadequate excitation. Consistency is considered to be a reliable indicator of accuracy. The new method is the culmination of many years of experience in developing a practical implementation of the eigensystem realization algorithm. The effectiveness of the method is illustrated using data from NASA Langley's controls-structures-interaction evolutionary model. C1 NASA,LANGLEY RES CTR,SPACECRAFT CONTROLS BRANCH,HAMPTON,VA 23681. GERMAN AEROSP RES ESTAB,INST AEROELAST DLR,W-3400 GOTTINGEN,GERMANY. RP PAPPA, RS (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,MAIL STOP 297,HAMPTON,VA 23681, USA. NR 12 TC 58 Z9 68 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1993 VL 16 IS 5 BP 852 EP 858 DI 10.2514/3.21092 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LW547 UT WOS:A1993LW54700006 ER PT J AU GAWRONSKI, W LIM, KB AF GAWRONSKI, W LIM, KB TI CONTROLLABILITY AND OBSERVABILITY OF FLEXIBLE STRUCTURES WITH PROOF-MASS ACTUATORS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID MODEL-REDUCTION; SYSTEMS AB Relationships between Hankel singular values of a structure with a proof-mass actuator to those of a structure with an ideal actuator are obtained for small damping and distinct natural frequencies. They indicate that if the natural frequency of the proof-mass actuator is much lower than the structural frequencies, the proof-mass actuator has little influence on Hankel singular values of a structure. This fact significantly simplifies controllability/observability analysis and model reduction of flexible structures under certain conditions. Results from numerical simulations verify the conclusions. C1 NASA,LANGLEY RES CTR,DIV GUIDANCE & CONTROL,SPACECRAFT CONTROLS BRANCH,HAMPTON,VA 23665. RP GAWRONSKI, W (reprint author), JET PROP LAB,GROUND ANTENNAS & FACIL,PASADENA,CA 91109, USA. NR 15 TC 3 Z9 3 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1993 VL 16 IS 5 BP 899 EP 902 DI 10.2514/3.21098 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LW547 UT WOS:A1993LW54700012 ER PT J AU JUANG, JN CHEN, CW PHAN, M AF JUANG, JN CHEN, CW PHAN, M TI ESTIMATION OF KALMAN FILTER GAIN FROM OUTPUT RESIDUALS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper presents a procedure to estimate the Kalman filter gain from input-output measurement data with a given system model. The system model can be a finite element model or an experimental model from any identification method. The procedure consists of three basic steps. First, the stochastic portion related to the residuals of the response is computed. Second, the coefficients of a linear difference model for the stochastic portion are estimated by a least-squares solution that minimizes the filter residual. Third, the Kalman filter gain is computed from these model coefficients. Experimental results are presented to illustrate the usefulness of the developed procedure. C1 N CAROLINA STATE UNIV,MARS MISSION RES CTR,RALEIGH,NC 27695. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23665. RP JUANG, JN (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 15 TC 2 Z9 2 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1993 VL 16 IS 5 BP 903 EP 908 DI 10.2514/3.21099 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LW547 UT WOS:A1993LW54700013 ER PT J AU WIBBELS, T BALAZS, GH OWENS, DW AMOSS, MS AF WIBBELS, T BALAZS, GH OWENS, DW AMOSS, MS TI SEX-RATIO OF IMMATURE GREEN TURTLES INHABITING THE HAWAIIAN ARCHIPELAGO SO JOURNAL OF HERPETOLOGY LA English DT Note ID CARETTA-CARETTA; TEMPERATURES; REPTILES; FLORIDA; BEACH C1 TEXAS A&M UNIV SYST,DEPT BIOL,COLL STN,TX 77843. NOAA,NATL MARINE FISHERIES SERV,SE FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. TEXAS A&M UNIV SYST,DEPT VET PHYSIOL & PHARMACOL,COLL STN,TX 77843. NR 28 TC 17 Z9 18 U1 0 U2 4 PU SOC STUD AMPHIBIANS REPTILES PI OXFORD PA DEPT OF ZOOLOGY MIAMI UNIV, OXFORD, OH 45056 SN 0022-1511 J9 J HERPETOL JI J. Herpetol. PD SEP PY 1993 VL 27 IS 3 BP 327 EP 329 DI 10.2307/1565155 PG 3 WC Zoology SC Zoology GA MB997 UT WOS:A1993MB99700014 ER PT J AU TAYLOR, GR AF TAYLOR, GR TI OVERVIEW OF SPACEFLIGHT IMMUNOLOGY STUDIES SO JOURNAL OF LEUKOCYTE BIOLOGY LA English DT Article DE SPACE IMMUNOLOGY; IMMUNE SUPPRESSION; INFECTIOUS RISK ID SPACE-FLIGHT; ANTIORTHOSTATIC SUSPENSION; SIMULATED WEIGHTLESSNESS; IMMUNE-RESPONSE; INTERFERON; EXERCISE; MODEL; RAT; SHUTTLE; STRESS AB The effects of spaceflight and analogues of spaceflight are discussed here and in nine accompanying articles. In this summary we present spaceflight studies with human subjects, animal subjects, and cell cultures and we review ground-based systems used to model the observed effects of spaceflight on the immune system. Human paradigms include bed rest, academic or psychological stress, physical stress, hypobaric or high altitude stress, and confinement. Animal models include antiorthostatic and orthogtatic suspension, hypobarism, and confinement. The ten manuscripts in this collection were selected to provide a summary that should give the reader an overview of the various activities of spaceflight immunology researchers throughout the history of space travel. This manuscript identifies the major contributors to the study of spaceflight immunology, explains what types of studies have been conducted, and how they have changed over the years. Also presented is a discussion of the unusual limitations associated with spaceflight research and the efforts to develop appropriate ground-based surrogate model systems. Specific details, data, and mechanistic speculations will be held to a minimum, because they will be discussed in depth in the other articles in the collection. RP TAYLOR, GR (reprint author), LB JOHNSON SPACE CTR,MAIL CODE SA,HOUSTON,TX 77058, USA. NR 73 TC 61 Z9 62 U1 0 U2 2 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0741-5400 J9 J LEUKOCYTE BIOL JI J. Leukoc. Biol. PD SEP PY 1993 VL 54 IS 3 BP 179 EP 188 PG 10 WC Cell Biology; Hematology; Immunology SC Cell Biology; Hematology; Immunology GA LW820 UT WOS:A1993LW82000001 PM 8371047 ER PT J AU TAYLOR, GR AF TAYLOR, GR TI IMMUNE CHANGES DURING SHORT-DURATION MISSIONS SO JOURNAL OF LEUKOCYTE BIOLOGY LA English DT Article DE SPACEFLIGHT; IMMUNE SUPPRESSION; HYPOERGY; HYPOGRAVITY ID SPACE-FLIGHT; SPACEFLIGHT; REACTIVITY; INTERFERON AB Spaceflight materially influences the immune mechanism of humans and animals. Effects resulting from missions of less than 1 month are examined. Effects from longer missions are discussed in the companion paper by Konstantinova et al. Most immunology studies have involved analyses of subjects and samples from subjects obtained after flight, with the data being compared with similar data obtained before flight. These studies have demonstrated that short-duration missions can result in a postflight depression in blast cell transformation, major changes in cytokine function, and alterations in the relative numbers of immune cell populations. In addition to these post- vs. preflight studies, some data have been produced in flight. However, these in vitro analyses have been less than satisfactory because of differences between in-flight and ground-control conditions. Recently, both the U.S. and Russian space programs have started collecting in-flight, in vivo, cell-mediated immunity data. These studies have confirmed that the human cell-mediated immune system is blunted during spaceflight. RP TAYLOR, GR (reprint author), LB JOHNSON SPACE CTR,MAIL CODE SA,HOUSTON,TX 77058, USA. NR 49 TC 44 Z9 46 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0741-5400 J9 J LEUKOCYTE BIOL JI J. Leukoc. Biol. PD SEP PY 1993 VL 54 IS 3 BP 202 EP 208 PG 7 WC Cell Biology; Hematology; Immunology SC Cell Biology; Hematology; Immunology GA LW820 UT WOS:A1993LW82000003 PM 8371049 ER PT J AU MEEHAN, R WHITSON, P SAMS, C AF MEEHAN, R WHITSON, P SAMS, C TI THE ROLE OF PSYCHONEUROENDOCRINE FACTORS ON SPACEFLIGHT-INDUCED IMMUNOLOGICAL ALTERATIONS SO JOURNAL OF LEUKOCYTE BIOLOGY LA English DT Article DE STRESS; HUMAN IMMUNOLOGY; NEUROENDOCRINE IMMUNOLOGY ID SPACE-FLIGHT; IMMUNE-SYSTEM; HUMAN-LYMPHOCYTES; PEPTIDE-HORMONES; NEURO-ENDOCRINE; STRESS; CELL; RESPONSES; IMMUNOREGULATION; RESPONSIVENESS AB This paper summarizes previous in-flight infections and novel conditions of spaceflight that may suppress immune function. Granulocytosis, monocytosis, and lymphopenia are routinely observed following short duration orbital flights. Subtle changes within the monocyte and T cell populations can also be noted by flow cytometric analysis. The similarity between the immunological changes observed after spaceflight and other diverse environmental stressors suggest that most of these alterations may be neuroendocrine-mediated. Available data support the hypothesis that spaceflight and other environmental stressors modulate normal immune regulation via stress hormones, other than exclusively glucocorticoids. It will be essential to simultaneously collect in-flight endocrine, immunologic, and infectious illness data to determine the clinical significance of these results. Additional research that delineates the neuroendocrine mechanisms of stress-induced changes in normal immune regulation will allow clinicians in the future to initiate prophylactic immunomodulator therapy to restore immune competence altered by the stress of long-duration spaceflight and therefore reduce morbidity from infectious illness, autoimmune disease, or malignancy. C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,HOUSTON,TX 77058. RP MEEHAN, R (reprint author), UNIV COLORADO,HLTH SCI CTR,DEPT MED,DIV RHEUMATOL,BOX B115,4200 E 9TH AVE,DENVER,CO 80262, USA. NR 83 TC 51 Z9 57 U1 0 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0741-5400 J9 J LEUKOCYTE BIOL JI J. Leukoc. Biol. PD SEP PY 1993 VL 54 IS 3 BP 236 EP 244 PG 9 WC Cell Biology; Hematology; Immunology SC Cell Biology; Hematology; Immunology GA LW820 UT WOS:A1993LW82000007 PM 8371053 ER PT J AU SUN, XH NI, LM AF SUN, XH NI, LM TI SCALABLE PROBLEMS AND MEMORY-BOUNDED SPEEDUP SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article ID PERFORMANCE C1 MICHIGAN STATE UNIV,DEPT COMP SCI,ADV COMP SYST LAB,E LANSING,MI 48824. RP SUN, XH (reprint author), NASA LANGLEY RES CTR,ICASE,HAMPTON,VA 23681, USA. NR 18 TC 60 Z9 70 U1 1 U2 6 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD SEP PY 1993 VL 19 IS 1 BP 27 EP 37 DI 10.1006/jpdc.1993.1087 PG 11 WC Computer Science, Theory & Methods SC Computer Science GA LV393 UT WOS:A1993LV39300003 ER PT J AU PERIGAUD, C DELECLUSE, P AF PERIGAUD, C DELECLUSE, P TI INTERANNUAL SEA-LEVEL VARIATIONS IN THE TROPICAL INDIAN-OCEAN FROM GEOSAT AND SHALLOW-WATER SIMULATIONS SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID SURFACE CURRENT; ATLANTIC-OCEAN; ARABIAN SEA; EL-NINO; MODEL; CALIFORNIA; ALTIMETRY; MONSOON; WAVES AB Sea level variations of the Indian Ocean north of 20-degrees-S are analyzed from Geosat satellite altimeter data over April 1985-September 1989. These variations are compared and interpreted with numerical simulations derived from a reduced gravity model forced by FSU observed winds over the same period. After decomposition into complex empirical orthogonal functions, the low-frequency anomalies are described by the first two modes for observations as well as for simulations. The sums of the two modes contain 34% and 40% of the observed and simulated variances, respectively. Averaged over the basin, the observed and simulated sea level changes are correlated by 0.92 over 1985-1988. The strongest change happens during the El Nino 1986-1987: between winter 1986 and summer 1987 the basin-averaged sea level rises by approximately 1 cm. These low-frequency variations can partly be explained by changes in the Sverdrup circulation. The southern tropical Indian Ocean between 10-degrees and 20-degrees-S is the domain where those changes are strongest: the averaged sea level rises by approximately 4.5 cm between winter 1986 and winter 1987. There, the signal propagates southwestward across the basin at a speed similar to free Rossby waves. Sensitivity of observed anomalies is examined over 1987-1988, with different orbit ephemeris, tropospheric corrections, and error reduction processes. The uncertainty of the basin-averaged sea level estimates is mostly due to the way the orbit error is reduced and reaches approximately 1 cm. Nonetheless, spatial correlation is good between the various observations and better than between observations and simulations. Sensitivity of simulated anomalies to the wind uncertainty, examined with FSU and ECMWF forcings over 1985-1988, shows that the variance of the simulations driven by ECMWF is 52% smaller, as FSU winds are stronger than ECMWF. Results show that the wind strength also affects the dynamic response of the ocean: anomalies propagate westward across the basin more than twice as fast with FSU than with ECMWF. It is found that the discrepancy is larger between ECMWF and FSU simulations than between observations and FSU simulations. C1 JET PROP LAB,PASADENA,CA 91109. UNIV PARIS 06,F-75230 PARIS 05,FRANCE. NR 40 TC 52 Z9 54 U1 1 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD SEP PY 1993 VL 23 IS 9 BP 1916 EP 1934 DI 10.1175/1520-0485(1993)023<1916:ISLVIT>2.0.CO;2 PG 19 WC Oceanography SC Oceanography GA LX819 UT WOS:A1993LX81900002 ER PT J AU WANG, TS CHEN, YS AF WANG, TS CHEN, YS TI UNIFIED NAVIER-STOKES FLOWFIELD AND PERFORMANCE ANALYSIS OF LIQUID ROCKET ENGINES SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB In an effort to improve the current composite solutions in the design and analysis of liquid propulsive engines, a computational fluid dynamics (CFD) model capable of calculating the reacting flows from the combustion chamber, through the nozzle to the external plume, is developed. Flowfields of a conical nozzle and the Space Shuttle main engine (SSME) fired at sea level are investigated. The CFD model, FDNS (finite difference Navier-Stokes), is a pressure-based, viscous, ideal gas/real gas, reactive flow code. An equilibrium chemistry algorithm is employed using the point implicit method. A conical nozzle with the same expansion ratio as the SSME nozzle is computed to study the shock formation in both the internal and external flowfields. The bell-shaped SSME nozzle is run at 100% power level at various flow conditions. The computed flow solutions and nozzle thrust performance are in good agreement with those of other standard codes and engine hot fire test data. C1 ENGN SCI INC,HUNTSVILLE,AL 35805. RP WANG, TS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 19 TC 40 Z9 40 U1 0 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1993 VL 9 IS 5 BP 678 EP 685 DI 10.2514/3.23675 PG 8 WC Engineering, Aerospace SC Engineering GA LX519 UT WOS:A1993LX51900002 ER PT J AU MAY, RD FRIEDL, RR AF MAY, RD FRIEDL, RR TI INTEGRATED BAND INTENSITIES OF HO2NO2 AT 220-K SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID PERNITRIC ACID; PEROXYNITRIC ACID; HOONO2; NO2; DECOMPOSITION; KINETICS; SPECTRUM; STATE AB Integrated intensities of the 803, 940, 1304, 1397, 1728, and 3540 cm-1 bands of peroxynitric acid (HO2NO2) have been measured at 220 K. Simultaneously-recorded u.v. (200-350 nm) and Fourier transform i.r. (700-4000 cm-1) spectra of low-pressure gas mixtures containing HO2NO2 predominantly were analyzed to determine the number densities of HO2NO2 in a multi-pass absorption cell within an error of approx. 10%. Absorption coefficients at 220 K in the strong 803 cm-1 band, which should be useful in the interpretation of atmospheric spectra containing spectral features of HO2NO2, are also reported at high-resolution (0.003 cm-1). RP MAY, RD (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 26 TC 17 Z9 17 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD SEP PY 1993 VL 50 IS 3 BP 257 EP 266 DI 10.1016/0022-4073(93)90076-T PG 10 WC Optics; Spectroscopy SC Optics; Spectroscopy GA LR454 UT WOS:A1993LR45400003 ER PT J AU MANATT, SL LANE, AL AF MANATT, SL LANE, AL TI A COMPILATION OF THE ABSORPTION CROSS-SECTIONS OF SO2 FROM 106 TO 403 NM SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID SULFUR-DIOXIDE; HIGH-RESOLUTION; UPPER LIMITS; IO; SPECTRUM; UV; ABUNDANCE; VENUS; REGION; IUE AB Available spectrophotometric data on absorption cross-sections of SO2 for the gas phase from 106 to 403 nm at 293 +/- 10 K have been evaluated and, where necessary, converted to a digital form. Plotting and comparing various overlapping data sets has demonstrated that systematic errors in wavelength and cross-section exist in the data sets. A scheme, which uses newer data sets that were recorded over limited wavelength ranges, to correct the wavelengths and cross-sections of older data sets, is discussed. In one region photoplate data were compared with spectrophotometric data. The spectral regions where reinvestigation is warranted are discussed. A data file of the cross-sections of SO2 was assembled from 106.1 to 403.7 nm at a resolution of 0.1 nm. RP MANATT, SL (reprint author), JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. NR 45 TC 77 Z9 77 U1 0 U2 11 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD SEP PY 1993 VL 50 IS 3 BP 267 EP 276 DI 10.1016/0022-4073(93)90077-U PG 10 WC Optics; Spectroscopy SC Optics; Spectroscopy GA LR454 UT WOS:A1993LR45400004 ER PT J AU STONE, HW PILAND, WM AF STONE, HW PILAND, WM TI 21ST-CENTURY SPACE TRANSPORTATION SYSTEM-DESIGN APPROACH - HL-20 PERSONNEL LAUNCH SYSTEM SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This article provides an introduction to and overview of the research that was conducted on the HL-20 lifting body and is documented in several articles in this issue of the Journal of Spacecraft and Rockets. The concept has been defined as an option for a personnel launch system (PLS) that is intended to carry six to eight Space Station Freedom crew persons. In this role the HL-20 will complement the Space Shuttle operation and ensure the ability to transport people to and from Earth orbit after the year 2000. The research covers a broad range of disciplines, including aerodynamics, aerodynamic heating and thermal protection systems, structural design, subsystem definition, trajectory and guidance system development for entry and abort, production and operations, and human factors. This article also presents the lifting-body heritage, design features of the concept, and HL-20/PLS mission requirements. RP STONE, HW (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 21 TC 13 Z9 13 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 521 EP 528 DI 10.2514/3.25561 PG 8 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000001 ER PT J AU WARE, GM CRUZ, CI AF WARE, GM CRUZ, CI TI AERODYNAMIC CHARACTERISTICS OF THE HL-20 SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Wind-tunnel tests were made from subsonic to hypersonic speeds to define the aerodynamic characteristics of the HL-20 lifting-body configuration. The data have been assembled into an aerodynamic database for flight analysis of this proposed vehicle. The wind-tunnel data indicated that the model was longitudinally and laterally stable (about a center-of-gravity location of 0.54 body length) over the test range from Mach 20 to 0.3. At hypersonic speeds, the HL-20 model trimmed at a lift/drag (L/D) ratio of 1.4. This value gives the vehicle a crossrange capability similar to that of the Space Shuttle. At subsonic speeds, the HL-20 has a trimmed L/D ratio of about 3.6. Replacing the flat-plate outboard fins with fins having an airfoil shape increased the maximum subsonic trimmed L/D to 4.2. RP WARE, GM (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE ANAL BRANCH,HAMPTON,VA 23665, USA. NR 11 TC 10 Z9 10 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 529 EP 536 DI 10.2514/3.25562 PG 8 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000002 ER PT J AU POWELL, RW AF POWELL, RW TI 6-DEGREE-OF-FREEDOM GUIDANCE AND CONTROL-ENTRY ANALYSIS OF THE HL-20 SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The ability of the HL-20 lifting body to fly has been evaluated for an automated (no pilot inputs) entry from atmospheric interface to landing. This evaluation was required to demonstrate that not only successful touchdown conditions would be possible for this low lift-to-drag-ratio vehicle (congruent-to 4), but also the vehicle would not exceed its design dynamic pressure limit of 400 psf during entry. This dynamic pressure constraint limit, coupled with limited available pitch-control authority at low supersonic speeds, restricts the available maneuvering capability for the HL-20 to acquire the runway. One result of this analysis was that this restrictive maneuvering capability does not allow the use of a model-following atmospheric entry-guidance algorithm, such as that used by the Space Shuttle, but instead requires a more adaptable guidance algorithm. Therefore, for this analysis, a predictor-corrector guidance algorithm was developed that would provide successful touchdown conditions while not violating the dynamic pressure constraint. A flight-control system was designed and incorporated, along with the predictor-corrector guidance algorithm, into a six-degree-of-freedom simulation. This simulation was tested under many combinations of off-nominal atmospheric density profiles and winds and showed that the HL-20 remained controllable. This simulation also indicated that the HL-20 could reach the landing site and execute a successful landing under all off-nominal conditions simulated. RP POWELL, RW (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE ANAL BRANCH,HAMPTON,VA 23665, USA. NR 6 TC 20 Z9 22 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 537 EP 542 DI 10.2514/3.25563 PG 6 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000003 ER PT J AU JACKSON, EB RIVERS, RA BAILEY, ML AF JACKSON, EB RIVERS, RA BAILEY, ML TI EFFECT OF LIFT-TO-DRAG RATIO IN PILOT RATING OF THE HL-20 LANDING TASK SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A man-in-the-loop simulation study of the handling qualities of the HL-20 lifting-body vehicle was made in a fixed-base simulation cockpit at NASA Langley Research Center. The purpose of the study was to identify and substantiate opportunities for improving the original design of the vehicle from a handling qualities and landing performance perspective. Using preliminary wind-tunnel data, a subsonic aerodynamic model of the HL-20 was developed. This model was adequate to simulate the last 75-90 s of the approach and landing. A simple flight-control system was designed and implemented. Using this aerodynamic model as a baseline, visual approaches and landings were made at several vehicle lift-to-drag ratios. Pilots rated the handling characteristics of each configuration using a conventional numerical pilot-rating scale. Results from the study showed a high degree of correlation between the lift-to-drag ratio and pilot rating. Level 1 pilot ratings were obtained when the L/D ratio was approximately 3.8 or higher. C1 NASA,LANGLEY RES CTR,DIV FLIGHT APPLICAT,AIRCRAFT OPERAT BRANCH,HAMPTON,VA 23665. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP JACKSON, EB (reprint author), NASA,LANGLEY RES CTR,DIV GUIDANCE & CONTROL,AIRCRAFT GUIDANCE & CONTROLS BRANCH,MS 489,HAMPTON,VA 23665, USA. NR 11 TC 3 Z9 3 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 543 EP 548 DI 10.2514/3.25564 PG 6 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000004 ER PT J AU WURSTER, KE STONE, HW AF WURSTER, KE STONE, HW TI AERODYNAMIC HEATING ENVIRONMENT DEFINITION THERMAL PROTECTION SYSTEM SELECTION FOR THE HL-20 SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Definition or the aerothermal environment is critical to any vehicle such as the HL-20 Personnel Launch System that operates within the hypersonic night regime. Selection of an appropriate thermal protection system design is highly dependent on the accuracy of the heating-environment prediction. It is demonstrated that the entry environment determines the thermal protection system design for this vehicle. The methods used to predict the thermal environment for the HL-20 Personnel Launch System vehicle are described. Comparisons of the engineering solutions with computational fluid dynamic predictions, as well as wind-tunnel test results, show good agreement. The aeroheating predictions over several critical regions of the vehicle, including the stagnation areas of the nose and leading edges, windward centerline and wing surfaces, and leeward surfaces, are discussed. Results of predictions based on the engineering methods found within the MINIVER aerodynamic heating code are used in conjunction with the results of the extensive wind-tunnel tests on this configuration to define a flight thermal environment. Finally, the selection of the thermal protection system based on these predictions and current technology is described. RP WURSTER, KE (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 32 TC 13 Z9 13 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 549 EP 557 DI 10.2514/3.25565 PG 9 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000005 ER PT J AU WEILMUENSTER, KJ GREENE, FA AF WEILMUENSTER, KJ GREENE, FA TI HL-20 COMPUTATIONAL FLUID-DYNAMICS ANALYSIS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The essential elements of a computational fluid dynamics analysis of the HL-20/personnel launch system aerothermal environment at hypersonic speeds including surface definition, grid generation, solution techniques, and visual representation of results are presented. Examples of solution technique validation through comparison with data from ground-based facilities are presented, along with results from computations at flight conditions. Computations at flight points indicate that real-gas effects have little or no effect on vehicle aerodynamics and, at these conditions, results from approximate techniques for determining surface heating are comparable with those obtained from Navier-Stokes solutions. RP WEILMUENSTER, KJ (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM,HAMPTON,VA 23665, USA. NR 20 TC 6 Z9 6 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 558 EP 566 DI 10.2514/3.25566 PG 9 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000006 ER PT J AU BUSH, LB ROBINSON, JC WAHLS, DM AF BUSH, LB ROBINSON, JC WAHLS, DM TI PRELIMINARY STRUCTURAL EVALUATION AND DESIGN OF THE HL-20 SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID PERSONNEL AB A lifting body concept, the HL-20, was designed at NASA Langley Research Center, and a structural analysis of the configuration with a cylindrical pressurized crew cabin was presented. Loads for the vehicle were assembled from mission loading conditions such as abort, on-orbit pressurization, blast overpressure, aerodynamic maneuver, and touchdown. The critical loading conditions were identified, and resultant loads were mapped onto the structure in order to review the effects of the mission loading conditions. The HL-20 structural concept was sized for the mission loads, and the resulting structural weights were calculated. C1 OLD DOMINION UNIV,RES FDN,NORFOLK,VA 23508. RP BUSH, LB (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE ANAL BRANCH,HAMPTON,VA 23665, USA. NR 13 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 567 EP 572 DI 10.2514/3.25567 PG 6 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000007 ER PT J AU STONE, HW MACCONOCHIE, IO AF STONE, HW MACCONOCHIE, IO TI HL-20 SUBSYSTEM DESIGN SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The NASA Langley Research Center has been developing a lifting-body configuration called the HL-20 for potential application as a personnel launch system orbiter that will provide the crew changeout at the Space Station Freedom. The objectives have been to provide an alternate manned access to space with a more cost-effective, efficient, reliable, and safer system for the routine transportation of people to low Earth orbit. The detailed study of this concept includes the subsystem design, flight software sizing, and mass properties that are discussed in this paper. The goals were to develop a subsystem complement to maximize operational efficiency with minimum development costs while using current technology. The subsystem selection and trade studies were made by a combination of NASA Langley Research Center, Rockwell International Space Systems Division, and Lockheed Advanced Development Company personnel. The results showed that current technology components will provide the required performance and operational effectiveness. Many of the selected components have Shuttle flight histories or considerable development heritage from other programs that will help minimize development costs. The sequential study of this concept by two major contractors with different perspectives resulted in similar subsystem selections and gave credibility to the concept approach. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23681. RP STONE, HW (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 19 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 590 EP 596 DI 10.2514/3.25570 PG 7 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000010 ER PT J AU MORRIS, WD WHITE, NH CALDWELL, RG AF MORRIS, WD WHITE, NH CALDWELL, RG TI HL-20 OPERATIONS AND SUPPORT REQUIREMENTS FOR THE PERSONNEL LAUNCH SYSTEM MISSION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The processing, mission planning, and support requirements were defined for the HL-20 lifting-body configuration that can serve as a Personnel Launch System. These requirements were based on the assumption of an operating environment that incorporates aircraft and airline support methods and techniques that are applicable to operations. The study covered the complete turnaround process for the HL-20, including landing through launch, and mission operations, but did not address the support requirements of the launch vehicle except for the integrated activities. Support is defined in terms of manpower, staffing levels, facilities, ground support equipment, maintenance/sparing requirements, and turnaround processing time. Support results were drawn from two contracted studies, plus an in-house analysis used to define the maintenance manpower. The results of the contracted studies were used as the basis for a stochastic simulation of the support environment to determine the sufficiency of support and the effect of variance on vehicle processing. Results indicate the levels of support defined for the HL-20 through this process to be sufficient to achieve the desired flight rate of eight flights per year. C1 ROCKWELL INT CORP,DIV SPACE SYST,LOGIST DEV,DOWNEY,CA 90241. RP MORRIS, WD (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE ANAL BRANCH,HAMPTON,VA 23665, USA. NR 18 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 597 EP 605 DI 10.2514/3.25571 PG 9 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000011 ER PT J AU WILLSHIRE, KF SIMONSEN, LC WILLSHIRE, WL AF WILLSHIRE, KF SIMONSEN, LC WILLSHIRE, WL TI HUMAN-FACTORS EVALUATION OF THE HL-20 FULL-SCALE MODEL SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The human factors testing of the HL-20 personnel launch system full-scale model was conducted in both the vertical and horizontal positions at NASA Langley Research Center. Three main areas of testing were considered: an anthropometric fit evaluation, the ingress and egress of a 10-person crew, and pilot viewing. The subjects, ranging from the 5th to 95th percentile size, had sufficient clearance in the model, with the exception of the last two rows of seats and the cockpit area. Adjustable seat heights and/or placement of the seats farther forward would provide more headroom. In the horizontal position, the model's seat placement and aisle width allowed a quick and orderly 10-person egress for the no-keel (a structural support running the length on the aisle), 6-in.-high keel, and 12-in.-high keel conditions. Egress times were less than 20 s. For the vertical position, the model's long cylindrical shape with the ladder in the ceiling allowed a quick and orderly egress with average times less than 30 s. Ingress and egress procedures were demonstrated using Shuttle partial-pressure suits. The reduced mobility experienced while wearing the suits did increase egress times, although they still remained acceptable. The window arrangement for pilot viewing was found to be reasonably acceptable, although slight modifications, such as an increased downward view, is desirable. C1 NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE ANAL BRANCH,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,DIV ACOUST,APPL ACOUST BRANCH,HAMPTON,VA 23665. RP WILLSHIRE, KF (reprint author), NASA,LANGLEY RES CTR,DIV INFORMAT SYST,AUTOMAT TECHNOL BRANCH,HAMPTON,VA 23665, USA. NR 14 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 606 EP 614 DI 10.2514/3.25572 PG 9 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000012 ER PT J AU BENSON, SW BEAVER, BA EDELMAN, AL SHOLES, EH AF BENSON, SW BEAVER, BA EDELMAN, AL SHOLES, EH TI TITAN-III FEASIBILITY FOR HL-20 PROTOTYPE MISSIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A set of studies was performed to investigate the feasibility of using the Titan HI launch vehicle to launch an unmanned prototype HL-20 personnel launch system and, potentially, operational HL-20 missions. The launch of an HL-20 spacecraft on a Titan III poses a unique set of concerns, primarily because the lifting body vehicle is carried on top of the Titan vehicle without a fairing. The Titan III/HL-20 feasibility study addressed the primary vehicle issues of performance, aerodynamics, loads, control and stability, launch availability, and vehicle configuration for the launch of an unmanned HL-20 prototype vehicle. Titan launch operations, launch site systems, and facilities were assessed to determine HL-20 operations compatibility. Additional studies determined the potential launch opportunity and window capabilities of the Titan III for the operational HL-20 mission and the existing Titan III's reliability. The feasibility study determined that the Titan III system, with minor changes, is compatible with the HL-20 vehicle and mission. It could provide nearly daily launch windows for a rendezvous with Space Station Freedom. Titan III reliability, when combined with the HL-20 launch escape system, provides a sufficiently high probability of crew survival to support its consideration as the primary vehicle for HL-20 operational missions. C1 ANALEX CORP,DEPT ADV SYST ANAL,BROOKPARK,OH 44142. NASA,LEWIS RES CTR,DIV ELECTR CONTROL SYST,CLEVELAND,OH 44135. MARTIN MARIETTA ASTRONAUT GRP,LAUNCH SYST ADV PROGRAMS,DENVER,CO 80201. RP BENSON, SW (reprint author), NASA,LEWIS RES CTR,ADV SPACE ANAL OFF,CLEVELAND,OH 44135, USA. NR 5 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 615 EP 621 DI 10.2514/3.25573 PG 7 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000013 ER PT J AU DUFFY, JB LEHNER, JW PANNELL, B AF DUFFY, JB LEHNER, JW PANNELL, B TI EVALUATION OF THE NATIONAL LAUNCH SYSTEM AS A BOOSTER FOR THE HL-20 SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The capability of a proposed national launch system (NLS) to boost the personnel launch system (PLS) manned vehicle has been examined. A reference NLS configuration, the NLS-2 1.5 stage vehicle, and a reference HL-20 PLS configuration were used for the study. Performance has been analyzed for several PLS insertion orbits to support the Space Station Freedom resupply mission. The reliability of the NLS launch vehicle and its contribution to crew safety requirements have been determined. The launch-processing and launch facility requirements of these combined systems were also analyzed. Previous studies of these two systems have focused on either the PLS manned element or NLS launch vehicle. This paper combines the results of prior studies in an analysis of the integrated NLS/PLS configuration. This analysis has found the proposed NLS 1.5 stage launch vehicle to be an excellent booster for the PLS. Predicted performance margins for this launch-vehicle configuration are more than adequate, and acceptable reliability and safety levels are anticipated. Integration of this NLS/PLS configuration into NASA mixed-fleet launch architectures is feasible. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,PROGRAM DEV,HUNTSVILLE,AL 35812. RP DUFFY, JB (reprint author), ROCKWELL INT CORP,DIV SPACE SYST,HUNTSVILLE,AL 35806, USA. NR 5 TC 3 Z9 3 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 622 EP 627 DI 10.2514/3.25574 PG 6 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000014 ER PT J AU NAFTEL, JC TALAY, TA AF NAFTEL, JC TALAY, TA TI ASCENT ABORT CAPABILITY FOR THE HL-20 SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The HL-20 has been designed with the capability for rescue of the crew during all phases of powered ascent from on the launch pad until orbital injection. A launch-escape system, consisting of solid rocket motors located on the adapter between the HL-20 and the launch vehicle, provides the thrust that propels the HL-20 to a safe distance from a malfunctioning launch vehicle. After these launch-escape motors have burned out, the adapter is jettisoned and the HL-20 executes one of four abort modes. In three abort modes-return-to-launch-site, transatlantic-abort-landing, and abort-to-orbit-not only is the crew rescued, but the HL-20 is recovered intact. In the ocean-landing-by-parachute abort mode, which occurs in between the return-to-launch-site and the transatlantic-abort-landing modes, the crew is rescued, but the HL-20 would likely sustain damage from the ocean landing. This paper describes the launch-escape system and the four abort modes for an ascent on a Titan III launch vehicle. RP NAFTEL, JC (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,MAIL STOP 365,HAMPTON,VA 23665, USA. NR 14 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 628 EP 634 DI 10.2514/3.25575 PG 7 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000015 ER PT J AU BLAIR, AB DILLON, JL WATSON, CB AF BLAIR, AB DILLON, JL WATSON, CB TI EXPERIMENTAL-STUDY OF TAIL-SPAN EFFECTS ON A CANARD-CONTROLLED MISSILE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB An experimental investigation was conducted on a cruciform canard-controlled missile configuration to determine the effects of tail span/canard span ratio on controllability. The investigation was conducted at Mach numbers from 1.75 to 3.50. Reductions of tail span/canard span ratio produced lower static margins and higher trim angle of attack. Results show that canard controls can provide pitch and yaw control as well as roll control by proper selection of the tail span/canard span ratio. RP BLAIR, AB (reprint author), NASA,LANGLEY RES CTR,DIV APPL AERODYNAM,SUPERSON HYPERSON AERODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 8 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1993 VL 30 IS 5 BP 635 EP 640 DI 10.2514/3.25576 PG 6 WC Engineering, Aerospace SC Engineering GA MB170 UT WOS:A1993MB17000016 ER PT J AU CURTIN, WA ELDRIDGE, JI SRINIVASAN, GV AF CURTIN, WA ELDRIDGE, JI SRINIVASAN, GV TI PUSH-OUT TESTS ON A NEW SILICON-CARBIDE REACTION-BONDED SILICON-CARBIDE CERAMIC-MATRIX COMPOSITE SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID MECHANICAL-PROPERTIES; FIBER; STRENGTH AB Fiber push-out tests have been performed on a ceramic matrix composite consisting of Carborundum sintered SiC fibers, with a BN coating, embedded in a reaction-bonded SiC matrix. Analysis of the push-out data, utilizing the most complete theory presently available, shows that one of the fiber/coating/matrix interfaces has a low fracture energy (one-tenth that of the fiber) and a moderate sliding resistance tau almost-equal-to 8 MPa. The debonded sliding interface shows some continuous but minor abrasion, which appears to increase the sliding resistance, but overall the system exhibits very clean smooth sliding. The tensile response of a full-scale composite is then modeled, using data obtained here and known fiber strengths, to demonstrate the good composite behavior predicted for this material. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. CARBORUNDUM CO,NIAGARA FALLS,NY 14302. RP CURTIN, WA (reprint author), BP RES,CLEVELAND,OH 44128, USA. NR 18 TC 19 Z9 19 U1 0 U2 7 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD SEP PY 1993 VL 76 IS 9 BP 2300 EP 2304 DI 10.1111/j.1151-2916.1993.tb07768.x PG 5 WC Materials Science, Ceramics SC Materials Science GA LZ616 UT WOS:A1993LZ61600020 ER PT J AU WEAVER, CJ DOUGLASS, AR ROOD, RB AF WEAVER, CJ DOUGLASS, AR ROOD, RB TI THERMODYNAMIC BALANCE OF 3-DIMENSIONAL STRATOSPHERIC WINDS DERIVED FROM A DATA ASSIMILATION PROCEDURE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CONSTITUENT TRANSPORT CALCULATIONS; SCHEME; MODEL; CONSERVATION AB The NASA/Goddard three-dimensional chemistry and transport model is driven by winds from a stratospheric data assimilation system. Synoptic- and planetary-scale patterns, apparent in satellite observations of trace constituents, are successfully reproduced for seasonal integrations. As model integrations proceed, however, the quality of simulations decreases, and systematic differences between calculation and measurement appear. The differences are explained by examining the zonal-mean residual circulation. The vertical residual velocity wBAR* is calculated two ways: (i) from the diabatic heating rates and temperature tendency and (ii) from the Eulerian vertical velocity and the horizontal eddy beat flux convergence. The results from these calculations differ substantially. Periodic insertion of observational data during the assimilation process continually shocks the general circulation model and produces these differences, which leads to an overestimate of the mean vertical heat and constituent transport. Such differences are expected to be general to all data assimilation products. This interpretation is corroborated by two-dimensional (2D) model calculations. When wBAR* is calculated from (ii), the 2D ozone evolution is unrealistic and qualitatively similar to the 3D model simulation. The 2D ozone evolution is reasonable when wBAR* is calculated from (i). C1 APPL RES CORP,LANDOVER,MD. RP WEAVER, CJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Douglass, Anne/D-4655-2012; Rood, Richard/C-5611-2008 OI Rood, Richard/0000-0002-2310-4262 NR 23 TC 40 Z9 40 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD SEP 1 PY 1993 VL 50 IS 17 BP 2987 EP 2993 DI 10.1175/1520-0469(1993)050<2987:TBOTDS>2.0.CO;2 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LY505 UT WOS:A1993LY50500011 ER PT J AU HIMELBLAU, H KERN, DL DAVIS, GL AF HIMELBLAU, H KERN, DL DAVIS, GL TI SUMMARY OF CASSINI ACOUSTIC CRITERIA DEVELOPMENT USING TITAN-IV FLIGHT DATA SO JOURNAL OF THE IES LA English DT Article DE CASSINI SPACECRAFT; TITAN-IV FLIGHT DATA; TITAN-IV PAYLOAD FAIRING; ACOUSTIC DATA; ACOUSTIC CRITERIA AB The Cassini spacecraft is being developed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration (NASA) to orbit and explore the planet Saturn, its rings, and satellites. Cassini will be launched on a Titan IV and boosted out of Earth orbit by a Centaur. This paper discusses the development of Cassini acoustic criteria using Titan IV flight data. Factors affecting the development of Cassini acoustic criteria using corrected Titan IV flight datal include the statistical methods used to account for spatial and flight-to-flight variations, the use of maximax spectra, data corrections for acoustic pressure increases near the payload fairing surfaces, and corrections for payload fill factor effects. Separate acoustic criteria were developed for the two launch sites. RP HIMELBLAU, H (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU INST ENVIRONMENTAL SCI PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 SN 1052-2883 J9 J IES JI J. IES PD SEP-OCT PY 1993 VL 36 IS 5 BP 19 EP 27 PG 9 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA MD943 UT WOS:A1993MD94300003 ER PT J AU TOTH, RA AF TOTH, RA TI 2-NU-2-NU-2 AND 2-NU-2 BANDS OF (H2O)-O-16, (H2O)-O-17, AND (H2O)-O-18 - LINE POSITIONS AND STRENGTHS SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article ID INTERACTING STATES 020; TRANSITION FREQUENCIES; CM-1; SPECTRUM; WATER; INTENSITIES; REGION; H2O-16; WAVE AB High-resolution spectra of (H2O)-O-16, (H2O)-O-17, and (H2O)-O-18 were recorded with a Fourier-transform spectrometer, covering transitions in the (020)-(010) and (020)-(000) bands. The measured line frequencies were used to determine high-accuracy values of rotational energy levels in the (020) vibrational states for the three isotopic species. Measurements of the line strengths were fitted to a model in which 19 transition moment parameters were determined for each band and molecule. The fitting technique did not consider interactions between the (020), (100), and (001) vibrational states. The experimental results provide a more accurate representation of the line positions and strengths than those currently available for these bands. RP TOTH, RA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 23 TC 61 Z9 61 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3224 J9 J OPT SOC AM B JI J. Opt. Soc. Am. B-Opt. Phys. PD SEP PY 1993 VL 10 IS 9 BP 1526 EP 1544 DI 10.1364/JOSAB.10.001526 PG 19 WC Optics SC Optics GA LV986 UT WOS:A1993LV98600004 ER PT J AU WHITSON, PA PIETRZYK, RA PAK, CYC CINTRON, NM AF WHITSON, PA PIETRZYK, RA PAK, CYC CINTRON, NM TI ALTERATIONS IN RENAL STONE RISK-FACTORS AFTER SPACE-FLIGHT SO JOURNAL OF UROLOGY LA English DT Article DE KIDNEY CALCULI; URINARY CALCULI; SPACE FLIGHT; AEROSPACE MEDICINE ID URINARY CITRATE EXCRETION; CALCIUM-OXALATE; NEPHROLITHIASIS; NUCLEATION; INHIBITORS; FORMERS; GROWTH AB Exposure to the microgravity environment of space produces a number of physiological changes of metabolic and environmental origin that could increase the potential for renal stone formation. Metabolic, environmental and physicochemical factors that influence renal stone risk potential were examined in 24-hour urine samples from astronauts 10 days before launch and on landing day to provide an immediate postflight assessment of these factors. In addition, comparisons were made between male and female crewmembers, and between crewmembers on missions of less than 6 days and those on 6 to 10-day missions. Results suggest that immediately after space flight the risk of calcium oxalate and uric acid stone formation is increased as a result of metabolic (hypercalciuria, hypocitraturia, pH) and environmental (lower urine volume) derangements, some of which could reflect residual effects of having been exposed to microgravity. C1 KRUG LIFE SCI,HOUSTON,TX. UNIV TEXAS,HLTH SCI CTR,SW MED SCH,MINERAL METAB SECT,DALLAS,TX 75235. RP WHITSON, PA (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,MAIL CODE SD4,HOUSTON,TX 77058, USA. NR 21 TC 39 Z9 40 U1 0 U2 1 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0022-5347 J9 J UROLOGY JI J. Urol. PD SEP PY 1993 VL 150 IS 3 BP 803 EP 807 PG 5 WC Urology & Nephrology SC Urology & Nephrology GA LR890 UT WOS:A1993LR89000002 PM 8345588 ER PT J AU MICHAELS, J AF MICHAELS, J TI LIBRARY AND INFORMATION-SCIENCE RESEARCH - ARE WE SCHOLARS OR PARASITES SO LIBRARY & INFORMATION SCIENCE RESEARCH LA English DT Article RP MICHAELS, J (reprint author), NASA,HEADQUARTERS LIB,300 E ST SW,WASHINGTON,DC 20546, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU ABLEX PUBL CORP PI NORWOOD PA 355 CHESTNUT ST, NORWOOD, NJ 07648 SN 0740-8188 J9 LIBR INFORM SCI RES JI Libr. Infor. Sci. Res. PD FAL PY 1993 VL 15 IS 4 BP 297 EP 298 PG 2 WC Information Science & Library Science SC Information Science & Library Science GA MN245 UT WOS:A1993MN24500001 ER PT J AU HILL, LL AF HILL, LL TI EDUCATION FOR LIBRARY AND INFORMATION MANAGEMENT CAREERS IN CORPORATE ENVIRONMENTS - INTRODUCTION SO LIBRARY TRENDS LA English DT Editorial Material RP HILL, LL (reprint author), NASA,SCI & TECH INFORMAT PROGRAM,WASHINGTON,DC 20546, USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU GSLIS PUBLICATIONS PI CHAMPAIGN PA 501 E DANIEL ST, CHAMPAIGN, IL 61820-6211 SN 0024-2594 J9 LIBR TRENDS JI Libr. Trends PD FAL PY 1993 VL 42 IS 2 BP 225 EP 231 PG 7 WC Information Science & Library Science SC Information Science & Library Science GA NB917 UT WOS:A1993NB91700001 ER PT J AU PAERL, HW BEBOUT, BM JOYE, SB MARAIS, DJD AF PAERL, HW BEBOUT, BM JOYE, SB MARAIS, DJD TI MICROSCALE CHARACTERIZATION OF DISSOLVED ORGANIC-MATTER PRODUCTION AND UPTAKE IN MARINE MICROBIAL MAT COMMUNITIES SO LIMNOLOGY AND OCEANOGRAPHY LA English DT Article ID OXYGENIC PHOTOSYNTHESIS; NITROGEN-FIXATION; N2 FIXATION; ECOLOGY; MICROELECTRODE; MICROALGAE; WATERS AB intertidal marine nucrobial mats exhibited biologically mediated uptake of low molecular weight dissolved organic matter (DOM), including D-glucose, acetate, and an L-amino acid mixture at trace concentrations. Uptake of all compounds occurred in darkness, but was frequently enhanced under natural illumination. The photosystem 2 inhibitor, 343,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) generally failed to inhibit light-stimulated DOM uptake. Occasionally, light plus DCMU-amended treatments led to uptake rates higher than light-incubated samples, possibly due to phototrophic bacteria present in subsurface anoxic layers. Uptake was similar with either H-3- or C-14-labeled substrates, indicating that recycling of labeled CO2 via photosynthetic fixation was not interfering with measurements of light-stimulated DOM uptake. Microautoradiographs showed a variety of pigmented and nonpigmented bacteria and, to a lesser extent, cyanobacteria and eucaryotic microalgae involved in light-mediated DOM uptake. Light-stimulated DOM uptake was often observed in bacteria associated with sheaths and mucilage surrounding filamentous cyanobacteria, revealing a close association of organisms taking up DOM with photoautotrophic members of the mat community. The capacity for dark- and light-mediated heterotrophy, coupled to efficient retention of fixed carbon in the mat community, may help optimize net production and accretion of mats, even in oligotrophic waters. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP PAERL, HW (reprint author), UNIV N CAROLINA,INST MARINE SCI,3431 ARENDELL ST,MOREHEAD CITY,NC 28557, USA. OI Joye, Samantha/0000-0003-1610-451X FU NCIPC CDC HHS [OCE 89-14833] NR 36 TC 41 Z9 42 U1 2 U2 11 PU AMER SOC LIMNOLOGY OCEANOGRAPH PI LAWRENCE PA 810 EAST 10TH ST, LAWRENCE, KS 66044-8897 SN 0024-3590 J9 LIMNOL OCEANOGR JI Limnol. Oceanogr. PD SEP PY 1993 VL 38 IS 6 BP 1150 EP 1161 PG 12 WC Limnology; Oceanography SC Marine & Freshwater Biology; Oceanography GA ME147 UT WOS:A1993ME14700005 PM 11539296 ER PT J AU TEWARI, SN ASTHANA, R NOEBE, RD AF TEWARI, SN ASTHANA, R NOEBE, RD TI INTERFACIAL SHEAR-STRENGTH OF CAST AND DIRECTIONALLY SOLIDIFIED NIAL-SAPPHIRE FIBER COMPOSITES SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article AB The feasibility of fabricating intermetallic NiAl-sapphire fiber composites by casting and zone directional solidification-has been examined. The fiber-matrix interfacial shear strengths measured using a fiber push-out technique in both cast and directionally solidified composites are greater than the strengths reported for composites fabricated by powder cloth process using organic binders. Microscopic examination of fibers extracted from cast, directionally solidified (DS), and thermally cycled composites, and the high values of interfacial shear strengths suggest that the fiber-matrix interface does not degrade due to casting and directional solidification. Sapphire fibers do not pin grain boundaries during directional solidification, suggesting that this technique can be used to fabricate sapphire fiber reinforced NiAl composites with single crystal matrices. C1 NASA,LEWIS RES CTR,INTERMET BRANCH,CLEVELAND,OH 44135. RP TEWARI, SN (reprint author), CLEVELAND STATE UNIV,DEPT CHEM ENGN,CLEVELAND,OH 44115, USA. NR 21 TC 19 Z9 19 U1 0 U2 1 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD SEP PY 1993 VL 24 IS 9 BP 2119 EP 2125 DI 10.1007/BF02666345 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA LU882 UT WOS:A1993LU88200021 ER PT J AU LIPSCHUTZ, ME WOLF, SF VOGT, S MICHLOVICH, E LINDSTROM, MM ZOLENSKY, ME MITTLEFEHLDT, DW SATTERWHITE, C SCHULTZ, L LOEKEN, T SCHERER, P DODD, RT SEARS, DWG BENOIT, PH WACKER, JF BURNS, RG FISHER, DS AF LIPSCHUTZ, ME WOLF, SF VOGT, S MICHLOVICH, E LINDSTROM, MM ZOLENSKY, ME MITTLEFEHLDT, DW SATTERWHITE, C SCHULTZ, L LOEKEN, T SCHERER, P DODD, RT SEARS, DWG BENOIT, PH WACKER, JF BURNS, RG FISHER, DS TI CONSORTIUM STUDY OF THE UNUSUAL H-CHONDRITE REGOLITH BRECCIA, NOBLESVILLE SO METEORITICS LA English DT Article ID PRODUCTION-RATES; COSMOGENIC NUCLIDES; TRACE-ELEMENTS; NOBLE-GASES; METEORITES; SOLAR; FAYETTEVILLE; COMPILATION; ABUNDANCES; EVOLUTION AB The Noblesville meteorite is a genomict, regolith breccia (H6 clasts in H4 matrix). Mossbauer analysis confirms that Noblesville is unusually fresh, not surprising in view of its recovery immediately after its fall. It resembles ''normal'' H4-6 chondrites in its chemical composition and induced thermoluminescence (TL) levels. Thus, at lest in its contents of volatile trace elements, Noblesville differs from other H chondrite, class A regolith breccias. Noblesville's small pre-atmospheric mass and fall near Solar maximum and/or its peculiar orbit (with perihelion <0.8 AU as shown by natural TL intensity) may partly explain its levels of cosmogenic radionuclides. Its cosmic ray exposure age of approximately 44 Ma, is long, is equalled or exceeded by <3% of all H chondrites, and also differs from the 33 +/- 3 Ma mean exposure age peak of other H chondrite regolith breccias. One whole-rock aliquot has a high, but not unmatched, Xe-129/Xe-132 of 1.88. While Noblesville is now among the chrondritic regolithic breccias richest in solar gases, elemental ratios indicate some loss, especially of He, perhaps by impacts in the regolith that heated individual grains. While general shock-loading levels in Noblesville did not exceed 4 GPa, individual clasts record shock levels of 5-10 GPa, doubtless acquired prior to lithification of the whole-rock meteoroid. C1 PURDUE UNIV, DEPT PHYS, W LAFAYETTE, IN 47907 USA. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. MAX PLANCK INST CHEM, W-6500 MAINZ, GERMANY. SUNY, DEPT EARTH & SPACE SCI, STONY BROOK, NY 11794 USA. LOCKHEED ENGN & SCI CO, HOUSTON, TX 77058 USA. MIT, DEPT EARTH ATMOSPHER & PLANETARY SCI, CAMBRIDGE, MA 02139 USA. UNIV ARKANSAS, DEPT CHEM BIOCHEM, FAYETTEVILLE, AR 72701 USA. PACIFIC NW LAB, RICHLAND, WA 99352 USA. RP LIPSCHUTZ, ME (reprint author), PURDUE UNIV, DEPT CHEM, W LAFAYETTE, IN 47907 USA. NR 61 TC 15 Z9 14 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1993 VL 28 IS 4 BP 528 EP 537 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LY908 UT WOS:A1993LY90800007 ER PT J AU SANDFORD, SA AF SANDFORD, SA TI THE MIDINFRARED TRANSMISSION SPECTRA OF ANTARCTIC UREILITES SO METEORITICS LA English DT Article ID DIFFUSE REFLECTANCE SPECTRA; METEORITE CLASSES; MU-M; ORIGIN; MINERALOGY; EVOLUTION AB The mid-infrared (4000-450 cm-1; 2.5-22.2 mum) transmission spectra of seven Antarctic ureilites and 10 Antarctic H-5 ordinary chondrites are presented. The ureilite spectra show a number of absorption bands, the strongest of which is a wide, complex feature centered near 1000 cm-1 (10 mum) due to Si-O stretching vibrations in silicates. The profiles and positions of the substructure in this feature indicate that Mg-rich olivines and pyroxenes are the main silicates responsible. The relative abundances of these two minerals, as inferred from the spectra, show substantial variation from meteorite to meteorite, but generally indicate olivine is the most abundant (olivine:pyroxene = 60:40 to 95:5). Both the predominance of olivine and the variable olivine-to-pyroxene ratio are consistent with the known composition and heterogeneity of ureilites. The H-5 ordinary chondrites spanned a range of weathering classes and were used to provide a means of addressing the extent to which the ureilite spectra may have been altered by weathering processes. It was found that, while weathering of these meteorites produces some weak bands due to the formation of small amounts of carbonates and hydrates, the profile of the main silicate feature has been little affected by Antarctic exposure in the meteorites studied here. The mid-infrared ureilite spectra provide an additional means of testing potential asteroidal parent bodies for the ureilites. At present, the best candidates include the subset of S-type asteroids having low albedos and weak absorption features in the near infrared. RP SANDFORD, SA (reprint author), NASA,AMES RES CTR,MS 245-6,MT VIEW,CA 94035, USA. NR 45 TC 11 Z9 11 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1993 VL 28 IS 4 BP 579 EP 585 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LY908 UT WOS:A1993LY90800012 PM 11539193 ER PT J AU AALFS, DD BAXA, EG BRACALENTE, EM AF AALFS, DD BAXA, EG BRACALENTE, EM TI SIGNAL-PROCESSING ASPECTS OF WINDSHEAR DETECTION SO MICROWAVE JOURNAL LA English DT Article ID SYSTEM; RADAR AB Low-altitude windshear (LAWS) has been identified as a major hazard to aircraft, particularly during takeoff and landing. The Federal Aviation Administration (FAA) has been involved with developing technology to detect LAWS. A key element in this technology is high resolution pulse Doppler weather radar equipped with signal and data processing to provide timely information about possible hazardous conditions. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. RP CLEMSON UNIV, CLEMSON, SC 29631 USA. NR 47 TC 3 Z9 4 U1 0 U2 0 PU HORIZON HOUSE PUBLICATIONS INC PI NORWOOD PA 685 CANTON ST, NORWOOD, MA 02062 USA SN 0192-6225 J9 MICROWAVE J JI Microw. J. PD SEP PY 1993 VL 36 IS 9 BP 76 EP + PG 1 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA MA036 UT WOS:A1993MA03600002 ER PT J AU DARDEN, WH BURNSIDE, WD GILREATH, MC AF DARDEN, WH BURNSIDE, WD GILREATH, MC TI AN ULTRA-WIDE-BAND ANTENNA FOR PULSED APPLICATIONS SO MICROWAVE JOURNAL LA English DT Article C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP DARDEN, WH (reprint author), OHIO STATE UNIV,DEPT ELECT ENGN,ELECTROSCI LAB,COLUMBUS,OH 43210, USA. NR 7 TC 0 Z9 1 U1 0 U2 0 PU HORIZON HOUSE-MICROWAVE PI NORWOOD PA 685 CANTON ST, NORWOOD, MA 02062 SN 0192-6225 J9 MICROWAVE J JI Microw. J. PD SEP PY 1993 VL 36 IS 9 BP 136 EP & PG 0 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA MA036 UT WOS:A1993MA03600007 ER PT J AU ORLANDINI, M AF ORLANDINI, M TI VELA X-1 AND ITS MISSING 3RD HARMONIC SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE BINARIES, CLOSE; PULSARS, INDIVIDUAL, VELA X-1; X-RAYS, STARS ID NEUTRON STARS; PULSE SHAPES; HOT SPOTS; EVOLUTION; PROFILES; SPECTRA; PERIOD AB In our analysis of 13 HEAO 1 A2 pointed observations of the X-ray binary pulsar Vela X-1, we have confirmed that its third pulsation harmonic is almost missing (the peak is approximately 2-3sigma above the continuum, with a drop of power of approximately 2 orders of magnitude with respect to the power present in the second harmonic). This feature is intrinsic to Vela X-1 and is independent of the timing resolution and the energy, although the harmonic content in the MED and HED data is quite different, because of the different pulse shape in the two energy bands. This drop has already been observed by the EXOSAT (although not pointed out) and the BBXRT observatories, and to our knowledge no other X-ray binary pulsar is known to show this peculiarity. For the high-energy data, we find a possible explanation of the phenomenon in the geometrical configuration of emission from radiating slabs at the polar caps, modelled according to Leahy. In order to model the low-energy harmonic content, we develop a phenomenological model of the Vela X-1 pulse profile in terms of two signals: a carrier with a double-peak structure, and a modulation with a five-peak structure. The harmonic content computed in the model is in agreement with the observations. Some possible physical interpretations of the two signals are discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771. RI Orlandini, Mauro/H-3114-2014 OI Orlandini, Mauro/0000-0003-0946-3151 NR 28 TC 3 Z9 3 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD SEP 1 PY 1993 VL 264 IS 1 BP 181 EP 190 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU929 UT WOS:A1993LU92900019 ER PT J AU KOCH, SE EINAUDI, F DORIAN, PB LANG, S HEYMSFIELD, GM AF KOCH, SE EINAUDI, F DORIAN, PB LANG, S HEYMSFIELD, GM TI A MESOSCALE GRAVITY-WAVE EVENT OBSERVED DURING CCOPE .4. STABILITY ANALYSIS AND DOPPLER-DERIVED WAVE VERTICAL STRUCTURE SO MONTHLY WEATHER REVIEW LA English DT Article ID RADAR OBSERVATIONS; BOUNDARY-LAYER; SQUALL-LINE; THERMODYNAMIC STRUCTURE; CONVECTIVE STORMS; MATCHING MODELS; RAMAN LIDAR; JULY 1983; DISTURBANCES; THUNDERSTORM AB This paper summarizes the results of a detailed study from the Cooperative Convective Precipitation Experiment (CCOPE) of the vertical structure of mesoscale gravity waves that disturbed a sizable part of the troposphere and that played a significant role in the generation of a mesoscale convective complex. These bimodal waves displayed periods of 148 (50) min, wavelengths of 135 (60) km, and phase speeds of 15.2 (19.8) m s-1. A comparison is made between wave-induced pressure perturbation fields derived from triple-Doppler wind fields within regions of essentially nonconvective precipitation, pressure perturbation fields obtained by bandpass filtering of surface mesonetwork data, and the vertical structure of the pressure eigenfunctions as predicted from a linear stability analysis. It is believed that this represents the first such application of the Doppler radar pressure retrieval technique to the study of gravity waves. In addition, an analysis of the potential for shear instability was performed on all of the special CCOPE soundings taken on this day to determine the representativeness of the chosen soundings for the theoretical analysis and the likelihood that a wave maintenance mechanism endured throughout the 33-h wave event. The analysis of the potential for shear instability and the eigenfunctions both indicate that the bimodal waves were able to efficiently extract energy from the mean flow near several closely spaced critical levels in the 4.0-6.5-km layer to maintain their coherence for many wave cycles. This result serves as the explanation for the observed ability of the waves to organize precipitation into long convective bands whose axes were along and just ahead of the wave crests. The eigenvalue analysis predicts unstable modes that are hydrostatic, nondispersive, ducted gravity waves characterized by half of a vertical wavelength contained between the ground and the lowest critical level (at z = 4 km). Eigenfunctions of pressure and other variables all display negligible tilt below 2.3-3.3 km, above which a sudden reversal in phase occurs. The vertical structure of the Doppler-derived fields associated with one of these gravity waves agrees in terms of the following respects with the eigenfunction predictions and/or the surface mesoanalyses: (a) the vertical wavelength, horizontal structure, and amplitude of the perturbation horizontal wind and pressure fields, and (b) the in-phase covariance between the pressure and horizontal wind fields at levels below 2.5 km. On the other hand, the theory predicted a much more abrupt vertical transition in phase in the pressure fields and weaker amplitudes aloft than were evident in the Doppler analyses. In addition, the size of the multiple-Doppler analysis domain was too small to capture an entire horizontal wavelength of the 135-km-scale gravity wave, which made direct comparisons difficult. Furthermore, the linear theory predicts much smaller amplitudes and somewhat longer horizontal wavelengths for the vertical motions characterizing both wave modes than those seen in the Doppler winds, which likely also contain nonwave effects. These discrepancies are largely due to the combined effects of weak convection, turbulence, and data sampling problems. Despite these drawbacks, the findings from this and other recent studies using Doppler radars and ground-based radiometers suggest that remote sensing of mesoscale gravity waves that occupy a significant fraction of the troposphere should be exploited further. C1 SSAI,GREENBELT,MD. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. GEN SCI CORP,LAUREL,MD. NR 65 TC 21 Z9 21 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD SEP PY 1993 VL 121 IS 9 BP 2483 EP 2510 DI 10.1175/1520-0493(1993)121<2483:AMGWEO>2.0.CO;2 PG 28 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LU353 UT WOS:A1993LU35300004 ER PT J AU MALERBA, F AF MALERBA, F TI THE 1ST MISSION OF THE TETHERED SATELLITE SO NUOVO CIMENTO DELLA SOCIETA ITALIANA DI FISICA C-GEOPHYSICS AND SPACE PHYSICS LA English DT Article; Proceedings Paper CT 6th Cosmic Physics National Conference CY NOV 03-07, 1992 CL PALERMO, ITALY AB The first test flight of the Italian Tethered Satellite was carried out from July 31 to August 8, 1992 on board the Space Shuttle Atlantis. This paper, authored by one of the crewmembers, directly involved with the Tethered Satellite Mission, describes the on-board experiment environment and the Payload Crew experience. RP MALERBA, F (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU EDITRICE COMPOSITORI BOLOGNA PI BOLOGNA PA VIA STALINGRADO 97/2, I-40128 BOLOGNA, ITALY SN 0390-5551 J9 NUOVO CIMENTO C JI Nuovo Cimento Soc. Ital. Fis. C-Geophys. Space Phys. PD SEP-OCT PY 1993 VL 16 IS 5 BP 485 EP 494 PG 10 GA MW387 UT WOS:A1993MW38700001 ER PT J AU CECCARELLI, C GRIFFIN, M ANDRE, P SARACENO, P MOLINARI, S RUSSELL, S AF CECCARELLI, C GRIFFIN, M ANDRE, P SARACENO, P MOLINARI, S RUSSELL, S TI ON THE NATURE OF CLASS-I SOURCES IN RHO-OPHIUCHUS SO NUOVO CIMENTO DELLA SOCIETA ITALIANA DI FISICA C-GEOPHYSICS AND SPACE PHYSICS LA English DT Article; Proceedings Paper CT 6th Cosmic Physics National Conference CY NOV 03-07, 1992 CL PALERMO, ITALY AB We present nun broad-band photometry of class-I sources in rho Ophiuchus that do not show signs of outflow activity. These sources have been considered as probable protostellar candidates, since they are among the most luminous members (few tens of solar luminosities) of this star-forming region and are heavily embedded, as shown by their steeply increasing spectra toward longer wavelengths. In comparison to some famous low-luminosity outflow (OF) sources, the non-outflow (NOF) sources show lower 1.3 mm fluxes, raising doubts as to their evolutionary stage. Our nun/submm data enabled us to derive the dust temperature and opacity power law exponent beta. From these we derive strong constraints on the mass surrounding these objects and conclude that NOF class-I sources in rho Ophiuchus have much less mass than OF sources with similar luminosities. We discuss the implications of such a finding in the evolutionary scenario of a young star. C1 QUEEN MARY & WESTFIELD COLL,LONDON,ENGLAND. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. CENS,F-91190 GIF SUR YVETTE,FRANCE. DUBLIN INST ADV STUDIES,DUBLIN 4,IRELAND. RP CECCARELLI, C (reprint author), CNR,IFSI,VIA G GALILEI,CP 27,I-00044 FRASCATI,ITALY. RI Molinari, Sergio/O-4095-2016 OI Molinari, Sergio/0000-0002-9826-7525 NR 0 TC 1 Z9 1 U1 0 U2 0 PU EDITRICE COMPOSITORI BOLOGNA PI BOLOGNA PA VIA STALINGRADO 97/2, I-40128 BOLOGNA, ITALY SN 0390-5551 J9 NUOVO CIMENTO C JI Nuovo Cimento Soc. Ital. Fis. C-Geophys. Space Phys. PD SEP-OCT PY 1993 VL 16 IS 5 BP 597 EP 603 DI 10.1007/BF02512040 PG 7 GA MW387 UT WOS:A1993MW38700010 ER PT J AU OMIDVAR, K AF OMIDVAR, K TI LOW-TEMPERATURE RADIATIVE RECOMBINATION OF ELECTRONS WITH BARE NUCLEI SO PHYSICAL REVIEW A LA English DT Article AB Aside from empirical formulas, the radiative-recombination cross section and coefficient are usually given in tabulated forms instead of analytic formulas. Here, we give analytic expressions in the form of expansions for the recombination cross section as a function of the electron energy E for low E, and for the recombination coefficient as a function of the temperature T for low T. The expansion coefficients are combinations of confluent hypergeometric functions, and are tabulated for a large number of the final principal and angular-momentum quantum numbers n and l. It is shown that the recombination cross section for arbitrary nuclear charge number Z is independent of Z, while the recombination coefficient for T/Z2 much lees than 1. 58 X 10(5) K increases as Z2. Excellent agreement is found with the published tabulated values. RP OMIDVAR, K (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 11 TC 1 Z9 1 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 SEP PY 1993 VL 48 IS 3 BP 1997 EP 2001 DI 10.1103/PhysRevA.48.1997 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA LX856 UT WOS:A1993LX85600037 ER PT J AU SCHLOSSER, H FERRANTE, J AF SCHLOSSER, H FERRANTE, J TI HIGH-PRESSURE EQUATION OF STATE FOR PARTIALLY IONIC SOLIDS SO PHYSICAL REVIEW B LA English DT Note ID ULTRASONIC PARAMETERS; BORN MODEL; HALIDES AB Recently, we showed that the cohesive energy of partially ionic solids may be characterized by a two-term energy relationship consisting of a Coulomb term arising from the valence-charge transfer deltaZ between the atoms, and a scaled universal energy function E*(a*), which accounts for the partially covalent character of the bond and for the repulsion between the atomic cores for small R; a* is a scaled length. Normalized cohesive-energy curves of alkali halide crystals and of Tl and Ag halide crystals were obtained, and the cohesive-energy-curve parameters were used to generate theoretical equation-of-state (EOS) curves for the Li, Na, K, Cs, and Ag halides. Good agreement was obtained with the experimental isothermal compression curves over a wide pressure range (0-90 kbar). In this paper we verify that the cohesive-energy relationship is valid for divalent partially ionic solids; physically reasonable charge-transfer values (1.80 < deltaZ < 2. 0) are obtained for MgO, CaO, and CaS. Next, EOS curves for LiF, NaF, NaI, CsCl, CsI, MgO, CaO, and CaS are generated in terms of the cohesive-energy parameters. These EOS's yield excellent fits to experimental isothermal-compression data and to shock-wave data to very high pressures (P(max) = 250-1350 kbar). C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SCHLOSSER, H (reprint author), CLEVELAND STATE UNIV,DEPT PHYS,CLEVELAND,OH 44115, USA. NR 16 TC 8 Z9 8 U1 0 U2 4 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD SEP 1 PY 1993 VL 48 IS 9 BP 6646 EP 6649 DI 10.1103/PhysRevB.48.6646 PG 4 WC Physics, Condensed Matter SC Physics GA LX348 UT WOS:A1993LX34800117 ER PT J AU JUNG, YD AF JUNG, YD TI PLASMA-SCREENING EFFECTS ON THE ELECTRON-IMPACT EXCITATION OF HYDROGENIC IONS IN DENSE-PLASMAS SO PHYSICS OF FLUIDS B-PLASMA PHYSICS LA English DT Article ID SCATTERING AB Plasma-screening effects are investigated on electron-impact excitation of hydrogenic ions in dense plasmas. Scaled cross sections Z4 . sigma for 1s --> 2s and 1s --> 2p are obtained for a Debye-Huckel model of the screened Coulomb interaction. Ground and excited bound wave functions are modified in the screened Coulomb potential (Debye-Huckel model) using the Ritz variation method. The resulting atomic wave functions and their eigenenergies agree well with the numerical and high-order perturbation theory calculations for the interesting domain of the Debye length LAMBDA/a(Z) greater-than-or-equal-to 10. The Born approximation is used to describe the continuum states of the projectile electron. Plasma screening effects on the atomic electrons cannot be neglected in the high-density cases. Including these effects, the cross sections are appreciably increased for 1s --> 2s transitions and decreased for 1s --> 2p transitions. C1 HANYANG UNIV,DEPT PHYS,KYUNGGI DO 425791,SOUTH KOREA. RP JUNG, YD (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-65,HUNTSVILLE,AL 35812, USA. NR 9 TC 78 Z9 78 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8221 J9 PHYS FLUIDS B-PLASMA PD SEP PY 1993 VL 5 IS 9 BP 3432 EP 3440 DI 10.1063/1.860636 PG 9 WC Physics, Fluids & Plasmas SC Physics GA LX855 UT WOS:A1993LX85500033 ER PT J AU NGHIEM, SV KWOK, R KONG, JA SHIN, RT AF NGHIEM, SV KWOK, R KONG, JA SHIN, RT TI A MODEL WITH ELLIPSOIDAL SCATTERERS FOR POLARIMETRIC REMOTE-SENSING OF ANISOTROPIC LAYERED MEDIA SO RADIO SCIENCE LA English DT Article ID STRONG PERMITTIVITY FLUCTUATIONS; SEA ICE; MICROWAVE-FREQUENCIES; DIELECTRIC-CONSTANT; THEORETICAL-MODELS AB This paper presents a model with ellipsoidal scatterers for applications to polarimetric remote sensing of anisotropic layered media at microwave frequencies. The physical configuration includes an isotropic layer covering an anisotropic layer above a homogeneous half space. The isotropic layer consists of randomly oriented spheroids. The anisotropic layer contains ellipsoidal scatterers with a preferential vertical alignment and random azimuthal orientations. Effective permittivities of the scattering media are calculated with the strong flucutation theory extended to account for the nonspherical shapes and the scatterer orientation distributions. On the basis of the analytic wave theory, dyadic Green's functions for layered media are used to derive polarimetric backscattering coefficients under the distorted Born approximation. The ellipsoidal shape of the scatterers gives rise to nonzero cross-polarized returns from the untilted anisotropic medium in the first-order approximation. Effects of rough interfaces are estimated by an incoherent addition method. Theoretical results and experimental data are matched at 9 GHz for thick first-year sea ice with a bare surface and with a snow cover at Point Bar-row, Alaska. The model is then used to study the sensitivity of polarimetric backscattering coefficients with respect to correlation lengths representing the geometry of brine inclusions. Polarimetric signatures of bare and snow-covered sea ice are also simulated based on the model to investigate effects of different scattering mechanisms. C1 MIT,DEPT ELECT ENGN & COMP SCI,CAMBRIDGE,MA 02139. MIT,RES RES LAB,CAMBRIDGE,MA 02139. RP NGHIEM, SV (reprint author), JET PROP LAB,MAIL STOP 300-235,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 27 TC 24 Z9 24 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD SEP-OCT PY 1993 VL 28 IS 5 BP 687 EP 703 DI 10.1029/93RS01605 PG 17 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA MC134 UT WOS:A1993MC13400004 ER PT J AU SISK, RC HELTON, AJ AF SISK, RC HELTON, AJ TI SCANNING INSTRUMENTATION FOR MEASURING MAGNETIC-FIELD TRAPPING IN HIGH-TC SUPERCONDUCTORS SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB Computerized scanning instrumentation measures and displays trapped magnetic fields across the surface of high T(c) superconductors at 77 K. Data are acquired in the form of a raster scan image utilizing stepping motor stages for positioning and a cryogenic Hall probe for magnetic field readout. Flat areas up to 45 mm in diameter are scanned with 0.5-mm resolution and displayed as false color images. RP SISK, RC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 6 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD SEP PY 1993 VL 64 IS 9 BP 2601 EP 2603 DI 10.1063/1.1143875 PG 3 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA LX891 UT WOS:A1993LX89100032 ER PT J AU WILT, DM HOFFMAN, RW AF WILT, DM HOFFMAN, RW TI A TECHNIQUE FOR ELIMINATING WHITE PHOSPHORUS DEPOSITS IN VAPOR-PHASE EPITAXY SYSTEMS SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Note AB A technique of heating the exhaust lines is described whereby phosphorus in the exhaust portion of an organometallic vapor phase epitaxy reactor is encouraged to deposit in the red form rather than the pyrophoric white form. This technique is simple, effective, and does not hinder or limit the conditions under which the reactor may be operated. C1 ANALEX CORP,CLEVELAND,OH 44135. RP WILT, DM (reprint author), NASA,LEWIS RES CTR,PHOTOVOLTAIC BRANCH,CLEVELAND,OH 44135, USA. NR 2 TC 0 Z9 0 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD SEP PY 1993 VL 64 IS 9 BP 2704 EP 2705 DI 10.1063/1.1143862 PG 2 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA LX891 UT WOS:A1993LX89100055 ER PT J AU ESPANA, MD PRALY, L AF ESPANA, MD PRALY, L TI ON THE GLOBAL DYNAMICS OF ADAPTIVE SYSTEMS - A STUDY OF AN ELEMENTARY EXAMPLE SO SIAM JOURNAL ON CONTROL AND OPTIMIZATION LA English DT Article DE ADAPTIVE SYSTEMS; INTERMITTENCY; DYNAMIC SYSTEMS; DISCRETE TIME SYSTEMS; PERIODIC SOLUTIONS; INVARIANT SETS AB The inherent nonlinear character of adaptive systems poses serious theoretical problems for the analysis of their dynamics. On the other hand. the importance of their dynamic behavior is directly related to the practical interest in predicting such undesirable phenomena as nonlinear oscillations, abrupt transients, intermittence or a high sensitivity with respect to initial conditions. A geometrical/qualitative description of the phase portrait of a discrete-time adaptive system with unmodeled disturbances is given. For this, the motions in the phase space are referred to normally hyperbolic (structurally stable) locally invariant sets. The study is complemented with a local stability analysis of the equilibrium point and periodic solutions. The critical character of adaptive systems under rather usual working conditions is discussed. Special emphasis is put on the causes leading to intermittence. A geometric interpretation of the effects of some commonly used palliatives to this problem is given. The ''dead-zone'' approach is studied in more detail. The predicted dynamics are compared with simulation results. C1 ECOLE MINES PARIS,CTR AUTOMAT & INFORMAT,F-77305 FONTAINEBLEAU,FRANCE. RP ESPANA, MD (reprint author), NASA AMES,DRYDEN FLIGHT RES FACIL,POB 273,MS D2002,EDWARDS AFB,CA 93523, USA. NR 29 TC 1 Z9 1 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 0363-0129 J9 SIAM J CONTROL OPTIM JI SIAM J. Control Optim. PD SEP PY 1993 VL 31 IS 5 BP 1143 EP 1166 PG 24 WC Automation & Control Systems; Mathematics, Applied SC Automation & Control Systems; Mathematics GA LV509 UT WOS:A1993LV50900005 ER PT J AU JESPERSEN, D AF JESPERSEN, D TI A FAMILY OF CUBIC EQUATIONS SO SIAM REVIEW LA English DT Letter RP JESPERSEN, D (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 0036-1445 J9 SIAM REV JI SIAM Rev. PD SEP PY 1993 VL 35 IS 3 BP 503 EP 504 DI 10.1137/1035103 PG 2 WC Mathematics, Applied SC Mathematics GA LW524 UT WOS:A1993LW52400009 ER PT J AU ALLEN, ER HOSSNER, LR MING, DW HENNINGER, DL AF ALLEN, ER HOSSNER, LR MING, DW HENNINGER, DL TI SOLUBILITY AND CATION-EXCHANGE IN PHOSPHATE ROCK AND SATURATED CLINOPTILOLITE MIXTURES SO SOIL SCIENCE SOCIETY OF AMERICA JOURNAL LA English DT Article ID SOILS; TEXAS AB Mixtures of zeolite and phosphate rock (PR) have the potential to provide slow-release fertilization of plants in synthetic soils by dissolution and ion-exchange reactions. This study was conducted to examine solubility and cation-exchange relationships in mixtures of PR and NH4- and K-saturated clinoptilolite (Cp). Batch-equilibration experiments were designed to investigate the effect of PR source, the proportion of exchangeable K and NH4, and the Cp to PR ratio on solution N, P, K, and Ca concentrations. The dissolution and cation-exchange reactions that occurred after mixing NH4- and K-saturated Cp with PR increased the solubility of the PR and simultaneously released NH, and K into solution. The more reactive North Carolina (NC) PR rendered higher solution concentrations of NH4 and K when mixed with Cp than did Tennessee (TN) PR. Solution P concentrations for the Cp-NC PR mixture and the Cp-TN PR mixture were similar. Solution concentrations of N, P, K, and Ca and the ratios of these nutrients in solution varied predictably with the type of PR, the Cp/PR ratio, and the proportions of exchangeable K and NH4 on the Cp. Our research indicated that slow-release fertilization using Cp/PR media may provide adequate levels of N, P, and K to support plant growth. Solution Ca concentrations were lower than optimum for plant growth. C1 TEXAS A&M UNIV SYST,DEPT SOIL & CROP SCI,COLL STN,TX 77840. NASA,JOHNSON SPACE CTR,HOUSTON,TX 77058. RP ALLEN, ER (reprint author), OKLAHOMA STATE UNIV,DEPT AGRON,STILLWATER,OK 74078, USA. NR 17 TC 34 Z9 44 U1 1 U2 4 PU SOIL SCI SOC AMER PI MADISON PA 677 SOUTH SEGOE ROAD, MADISON, WI 53711 SN 0361-5995 J9 SOIL SCI SOC AM J JI Soil Sci. Soc. Am. J. PD SEP-OCT PY 1993 VL 57 IS 5 BP 1368 EP 1374 PG 7 WC Soil Science SC Agriculture GA ME793 UT WOS:A1993ME79300035 PM 11537990 ER PT J AU THOMPSON, WT NEUPERT, WM JORDAN, SD JONES, H THOMAS, RJ SCHMIEDER, B AF THOMPSON, WT NEUPERT, WM JORDAN, SD JONES, H THOMAS, RJ SCHMIEDER, B TI CORRELATION OF HE-II LYMAN-ALPHA WITH HE-I 10830-ANGSTROM, AND WITH CHROMOSPHERIC AND EUV CORONAL EMISSION SO SOLAR PHYSICS LA English DT Article ID SOLAR CORONA AB This paper describes the results of comparing SERTS-3 images obtained in the transition region line of He II 304 angstrom with chromospheric He I 10830 angstrom absorption, with strong coronal lines of Mg IX 368 angstrom, Fe XV 284 angstrom and 417 angstrom, and Fe XVI 335 angstrom and 31 angstrom, with Halpha, with Ca II 8542 angstrom, and with magnetograms in Fel 8688Halpha. All of the images are illustrated, and the image reconstruction techniques used are described and evaluated. The high correlation of the He II 304 angstrom and He I 10830 angstrom images, originally found by Harvey and Sheeley (1977), is confirmed and is put on a quantitative basis. We find that the supergranulation network has greater contrast, and that filaments appear darker, in 10830 angstrom than in 304 angstrom. In active regions, the 304 angstrom line follows more closely the behavior of Halpha and Ca II 8542 angstrom than the 10830 angstrom line. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. OBSERV PARIS,SECT MEUDON,UA 326,F-92195 MEUDON,FRANCE. RP THOMPSON, WT (reprint author), APPL RES CORP,8201 CORPORATE DR,LANDOVER,MD 20785, USA. RI Thompson, William/D-7376-2012 NR 18 TC 16 Z9 16 U1 0 U2 0 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 SEP PY 1993 VL 147 IS 1 BP 29 EP 46 DI 10.1007/BF00675485 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LV274 UT WOS:A1993LV27400003 ER PT J AU WANG, AH WU, ST SUESS, ST POLETTO, G AF WANG, AH WU, ST SUESS, ST POLETTO, G TI A 2-DIMENSIONAL MHD GLOBAL CORONAL MODEL - STEADY-STATE STREAMERS SO SOLAR PHYSICS LA English DT Article ID EVOLUTION; FLOWS; HOLE AB We describe a two-dimensional time-dependent, numerical, magnetohydrodynamic model for the determination of the physical properties of coronal streamers from the top of the transition zone (R. = 1) to 15 R.. Four examples are given: for dipole, quadrupole, and hexapole initial field topologies. The computed parameters are density, temperature, velocity, and magnetic field. In addition to the properties of the solutions, their accuracy is discussed. We use the model as the basis for a general discussion of the way boundary conditions are specified in this and similar simulations. C1 UNIV ALABAMA,DEPT MECH ENGN,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SCI LAB,HUNTSVILLE,AL 35812. OSSERV ASTROFIS ARCETRI,I-50125 FLORENCE,ITALY. RP WANG, AH (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERONOM RES,HUNTSVILLE,AL 35899, USA. NR 15 TC 51 Z9 53 U1 0 U2 0 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 SEP PY 1993 VL 147 IS 1 BP 55 EP 71 DI 10.1007/BF00675487 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LV274 UT WOS:A1993LV27400005 ER PT J AU NOCI, G POLETTO, G SUESS, ST WANG, AH WU, ST AF NOCI, G POLETTO, G SUESS, ST WANG, AH WU, ST TI L-ALPHA INTENSITY IN CORONAL STREAMERS SO SOLAR PHYSICS LA English DT Article ID ELECTRON-DENSITY DISTRIBUTION; SOLAR CORONA; REGIONS; FLOWS; WIND AB White-light images are presently the primary source of information on physical conditions in the solar corona at distances greater than a few tenths of a solar radius above the limb. As a consequence, we still only have an incomplete description of structures extending beyond the solar limb. In particular, streamers, although observed for decades, represent a poorly known phenomenon. SOHO, to be launched in 1995, will be able to make long-term observations of these features up to heights of a few R., both in white light and UV. In this paper we present simulations of Lalpha intensity in coronal streamers, based on the two-dimensional (2-D) model developed by Wang et al. (1992, 1993) via a time-dependent numerical relaxation approach. Because the model is 2-D, we make an a priori hypothesis about the extension of streamers in the third dimension. Lalpha data, obtained from a rocket (Kohl et al., 1983), allowed us to identify a shape which fits the observations. We consider streamers with different magnetic field configurations and at different position angles with respect to the plane of the sky to illustrate how different regions along the line of sight contribute to the emergent intensity. Our purpose is twofold: to provide guidelines for UVCS observational operations and to explore the parameter space in order to understand the role of geometric factors and of the physical state of the corona in determining the overall streamer brightness. We conclude by showing how the results guide the future development of streamer models. C1 OSSERV ASTROFIS ARCETRI,I-50125 FLORENCE,ITALY. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,CTR SPACE PLASMA & AERONOM RES,HUNTSVILLE,AL 35899. RP NOCI, G (reprint author), UNIV FLORENCE,DIPARTIMENTO ASTRON & SCI SPAZIO,I-50121 FLORENCE,ITALY. NR 30 TC 10 Z9 10 U1 0 U2 0 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 SEP PY 1993 VL 147 IS 1 BP 73 EP 96 DI 10.1007/BF00675488 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LV274 UT WOS:A1993LV27400006 ER PT J AU ESCHER, WJD MOSES, JL GORLAND, SH STEPHENSON, FW AF ESCHER, WJD MOSES, JL GORLAND, SH STEPHENSON, FW TI STATUS OF NASA EARTH-TO-ORBIT PROPULSION TECHNOLOGY PROGRAM SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 05-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB NASA's Earth-to-Orbit (ETO) Propulsion Technology Program, was formalized as such in 1981 as part of the agency's Space Research and Technology Program and in 1988 was moved into the agency's Civil Space Technology Initiative (CSTI) as a focused program. It continues its traditional advanced propulsion technology development and verification character at an enhanced level of investment ($20-30 million annually). Approximately 185 tasks addressing liquid rocket engine subsystems, components and generic analysis and design methodologies are presently being conducted by industrial contractors, universities and within five NASA research and flight-program center, This work is distributed among the Program's three major technical areas: combustion devices, turbo-machinery and controls and monitoring, with a small number of special tasks being carried out in a fourth ''systems level'' study arena, principally to provide planning visibility for the Program. Ultimately directed toward markedly reducing acquisition and operations risk and cost, as a focused-technology effort, the ETO Program is conducted in two serially-performed program categories: technology acquisition and technology validation. The former is constituted by studies, ''tool building'', and bench-scale experimentation. often toward proof-of-concept demonstrations. The latter involves next-step verification of the acquisition results and findings, usually leading to a test-bed validated technology ''product'' which, with success, is now ready for incorporation into flight-system propulsion development programs as needs arise. RP ESCHER, WJD (reprint author), NASA,HEADQUARTERS,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD SEP PY 1993 VL 13 IS 5 BP 457 EP 466 PG 10 WC Engineering, Aerospace SC Engineering GA LT843 UT WOS:A1993LT84300001 ER PT J AU ROSEN, R RECK, GM BENNETT, GL AF ROSEN, R RECK, GM BENNETT, GL TI APPLICATIONS OF NUCLEAR PROPULSION TO MARS MISSIONS SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 05-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB Planning for a piloted mission to Mars entails consideration of a number of critical technologies-chief among these technologies is transportation. Transits to Mars are basically a double rendezvous problem: with Mars on the outbound leg while considering the alignments of Mars and Earth for the return to Earth. Nuclear propulsion, whether nuclear thermal propulsion (NEP) in which the reactor directly heats the propellant or nuclear electric propulsion (NEP) in which the reactor provides the electrical power for electromagnetically accelerating the propellant, offers several important benefits, including increased specific impulse, elimination of the oxider, and a decoupling of the energy source from the propellant. Studies have shown that the application of nuclear propulsion to Mars mission can shorten transit times for the same initial mass into low Earth orbit (IMLEO) or reduce the IMLEO for the same transit times. In addition the greater performance benefits of nuclear propulsion can provide the added margin for greater operational flexibility, including mission abort options and increased launch windows. During the 1950s and 1960s experimental and analytical studies showed the feasibility of nuclear propulsion. NASA, in cooperation with other agencies and organizations, is currently planning a technology development program for nuclear propulsion. The overall objective is to develop at least one NTP concept and one NEP concept for piloted and robotic (e.g. cargo) missions to Mars. RP ROSEN, R (reprint author), NASA,HEADQUARTERS,WASHINGTON,DC 20546, 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, ENGLAND OX5 1GB SN 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD SEP PY 1993 VL 13 IS 5 BP 467 EP 478 PG 12 WC Engineering, Aerospace SC Engineering GA LT843 UT WOS:A1993LT84300002 ER PT J AU ERB, RB AF ERB, RB TI POWER FROM SPACE FOR THE NEXT CENTURY SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article AB This paper addresses the role of power from space for use on Earth in the next century. It synopsizes the problems associated with our present practices of supplying power for the world in the face of a projected increase in demand and notes the need to reduce the use of fossil fuels. The probable shortfall by the middle of the next century is estimated and options for Earth-based and space-based sources of energy are examined. The paper concludes that energy obtained from space is a viable and necessary way of meeting a significant part of the world's needs in the next century. Furthermore, energy from such a source will contribute to these needs in a way that would be gentle to the Earth. If this conclusion is valid, then the topic must be placed on the agenda of the world's energy and aerospace communities and promoted as a significant part of what space-faring can do for humankind. RP ERB, RB (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,CANADIAN SPACE AGCY,CANADIAN LIAISON OFF,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD SEP PY 1993 VL 13 IS 5 BP 525 EP 533 PG 9 WC Engineering, Aerospace SC Engineering GA LT843 UT WOS:A1993LT84300007 ER PT J AU BOURLAND, CT AF BOURLAND, CT TI THE DEVELOPMENT OF FOOD SYSTEMS FOR SPACE SO TRENDS IN FOOD SCIENCE & TECHNOLOGY LA English DT Article AB The development of space food has evolved from tubes and cubes to near Earth-like cuisine over the past 30 years. Improvements in the habitability of spacecraft have permitted notable progress in the development of space food. However, there are many unresolved problems related to space food such as nutritional requirements, the variety required, and methods of preservation for long-duration missions. RP BOURLAND, CT (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV FLIGHT CREW SUPPORT,HOUSTON,TX 77058, USA. NR 22 TC 19 Z9 19 U1 7 U2 10 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0924-2244 J9 TRENDS FOOD SCI TECH JI Trends Food Sci. Technol. PD SEP PY 1993 VL 4 IS 9 BP 271 EP 276 DI 10.1016/0924-2244(93)90069-M PG 6 WC Food Science & Technology SC Food Science & Technology GA MA490 UT WOS:A1993MA49000001 ER PT J AU MULLIGAN, JB AF MULLIGAN, JB TI NONLINEAR COMBINATION RULES AND THE PERCEPTION OF VISUAL-MOTION TRANSPARENCY SO VISION RESEARCH LA English DT Article DE MOTION PERCEPTION; LINEARITY; TRANSPARENCY ID COHERENCE; LUMINANCE AB Experiments were performed to elucidate the decomposition performed by the human visual system in the segregation of complex motion stimuli into distinct moving surfaces. Subjects were presented with achromatic patterns consisting of four types of elements; generated from two random binary luminance patterns (random-dot checkerboards). The luminance of each of the four region classes was under program control. Animated sequences of such images were produced by displacing each of the two generating patterns in opposite directions on a frame by frame basis. These displays evoke a wide variety of percepts, depending on the programmed luminance values, including motion in a single direction, simultaneous motions of transparent sheets in opposite directions, dynamic noise with no directional component, or any combination of the above percepts. A theory is presented which relates the strengths of these percepts to the amplitudes of the components in the perceptual decomposition. The experiments described measured thresholds for seeing noise or ''twinkling'' in addition to the multiple motions, with the goal of determining the particular signal transformations preceding motion analysis. The results are consistent with a motion extraction mechanism which operates on a linear representation of the input imagery. These results extend a similar finding due to Anstis and Mather [(1985) Perception, 14, 167-179] and call into question the interpretation of a recent study by Stoner, Allbright and Ramachandran [(1990) Nature (London), 344, 153-155]. RP MULLIGAN, JB (reprint author), NASA,AMES RES CTR,MAIL STOP 262-2,MOFFETT FIELD,CA 94035, USA. NR 26 TC 21 Z9 21 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0042-6989 J9 VISION RES JI Vision Res. PD SEP PY 1993 VL 33 IS 14 BP 2021 EP 2030 DI 10.1016/0042-6989(93)90025-R PG 10 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA LQ241 UT WOS:A1993LQ24100011 PM 8249317 ER PT J AU EVANS, BR MARGALIT, R WOODWARD, J AF EVANS, BR MARGALIT, R WOODWARD, J TI ATTACHMENT OF PENTAAMMINERUTHENIUM(III) TO TRICHODERMA-REESEI CELLOBIOHYDROLASE-I INCREASES ITS CATALYTIC ACTIVITY SO BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS LA English DT Article ID PHANEROCHAETE-CHRYSOSPORIUM; CELLOBIOSE OXIDASE; FUNGAL CELLULASES; PURIFICATION; PEROXIDASE; REDUCTION; MYOGLOBIN; OXYGEN C1 OAK RIDGE NATL LAB,DIV CHEM TECHNOL,OAK RIDGE,TN 37831. JET PROP LAB,PASADENA,CA 91109. NR 25 TC 6 Z9 6 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0006-291X J9 BIOCHEM BIOPH RES CO JI Biochem. Biophys. Res. Commun. PD AUG 31 PY 1993 VL 195 IS 1 BP 497 EP 503 DI 10.1006/bbrc.1993.2071 PG 7 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA LU459 UT WOS:A1993LU45900072 PM 8363625 ER PT J AU KANIK, I AJELLO, JM JAMES, GK AF KANIK, I AJELLO, JM JAMES, GK TI EXTREME-ULTRAVIOLET EMISSION-SPECTRUM OF CO2 INDUCED BY ELECTRON-IMPACT AT 200 EV SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CROSS-SECTIONS; VACUUM ULTRAVIOLET; MEDIUM-RESOLUTION; RYDBERG SERIES; EXCITATION; N-2; STATE; H-2 AB We present the extreme ultraviolet (EUV) emission spectrum of CO2 induced by electron impact at 200 eV. There are 36 spectral features which are identified with a resolution of 0.5 nm over the wavelength range of 40 to 125 nm. Absolute emission cross sections were obtained for each of these features. The EUV emission spectrum induced by electron impact consists of atomic multiplets of CI, II and OI, II, III as well as CO and CO+ molecular band systems produced by dissociative excitation. The CI (119.4 nm) multiplet is the strongest feature of CI with a peak cross section of 3.61 x 10(-19) cm2 at 200 eV. The strongest feature of OI in the EUV spectrum is the OI (99.0 nm) multiplet with a peak cross section of 3.59 x 10(-19) cm2 at 200 eV. RP KANIK, I (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 26 TC 11 Z9 11 U1 0 U2 2 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 AUG 27 PY 1993 VL 211 IS 6 BP 523 EP 528 DI 10.1016/0009-2614(93)80137-E PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LU146 UT WOS:A1993LU14600004 ER PT J AU WEBSTER, CR MAY, RD TOOHEY, DW AVALLONE, LM ANDERSON, JG NEWMAN, P LAIT, L SCHOEBERL, MR ELKINS, JW CHAN, KR AF WEBSTER, CR MAY, RD TOOHEY, DW AVALLONE, LM ANDERSON, JG NEWMAN, P LAIT, L SCHOEBERL, MR ELKINS, JW CHAN, KR TI CHLORINE CHEMISTRY ON POLAR STRATOSPHERIC CLOUD PARTICLES IN THE ARCTIC WINTER SO SCIENCE LA English DT Article ID ANTARCTIC OZONE; TRACE GASES; VORTEX; HCL; DENITRIFICATION; ATMOSPHERE; CL2O2; DIMER; HOLE; HNO3 AB Simultaneous in situ measurements of hydrochloric acid (HCl) and chlorine monoxide (ClO) in the Arctic winter vortex showed large HCl losses, of up to 1 part per billion by volume (ppbv), which were correlated with high ClO levels of up to 1.4 ppbv. Air parcel trajectory analysis identified that this conversion of inorganic chlorine occurred at air temperatures of less than 196 +/- 4 kelvin. High ClO was always accompanied by loss of HCl mixing ratios equal to 1/2(ClO + 2Cl2O2). These data indicate that the heterogeneous reaction HCl + ClONO2 --> Cl2 + HNO3 on particles of polar stratospheric clouds establishes the chlorine partitioning, which, contrary to earlier notions, begins with an excess of ClONO2, not HCl. C1 UNIV CALIF IRVINE,DEPT GEOSCI,IRVINE,CA 92717. HARVARD UNIV,ATMOSPHER RES PROJECT,CAMBRIDGE,MA 02138. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. RP WEBSTER, CR (reprint author), JET PROP LAB,MS 183-401,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Toohey, Darin/A-4267-2008; Newman, Paul/D-6208-2012 OI Toohey, Darin/0000-0003-2853-1068; Newman, Paul/0000-0003-1139-2508 NR 42 TC 140 Z9 140 U1 0 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 27 PY 1993 VL 261 IS 5125 BP 1130 EP 1134 DI 10.1126/science.261.5125.1130 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU586 UT WOS:A1993LU58600020 PM 17790344 ER PT J AU TOOHEY, DW AVALLONE, LM LAIT, LR NEWMAN, PA SCHOEBERL, MR FAHEY, DW WOODBRIDGE, EL ANDERSON, JG AF TOOHEY, DW AVALLONE, LM LAIT, LR NEWMAN, PA SCHOEBERL, MR FAHEY, DW WOODBRIDGE, EL ANDERSON, JG TI THE SEASONAL EVOLUTION OF REACTIVE CHLORINE IN THE NORTHERN-HEMISPHERE STRATOSPHERE SO SCIENCE LA English DT Article AB In situ measurements of chlorine monoxide (ClO) at mid- and high northern latitudes are reported for the period 1991 to February 1992. As early as mid-December and throughout the winter, significant enhancements of this ozone-destroying radical were observed within the polar vortex shortly after temperatures dropped below 195 k. Decreases in ClO observed in February were consistent with the rapid formation of chlorine nitrate (ClONO2) by recombination of ClO with nitrogen dioxide (NO2) released photochemically from nitric acid (HNO3). Outside the vortex, ClO abundances were higher than in previous years as a result of NO(x) suppression by heterogeneous reactions on sulfate aerosols enhanced by the eruption of Mount Pinatubo. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NOAA,AERON LAB,BOULDER,CO 80303. HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. RP TOOHEY, DW (reprint author), UNIV CALIF IRVINE,DEPT GEOSCI,IRVINE,CA 92717, USA. RI Toohey, Darin/A-4267-2008; Newman, Paul/D-6208-2012; Fahey, David/G-4499-2013 OI Toohey, Darin/0000-0003-2853-1068; Newman, Paul/0000-0003-1139-2508; Fahey, David/0000-0003-1720-0634 NR 18 TC 60 Z9 60 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 27 PY 1993 VL 261 IS 5125 BP 1134 EP 1136 DI 10.1126/science.261.5125.1134 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU586 UT WOS:A1993LU58600021 PM 17790345 ER PT J AU TOON, O BROWELL, E GARY, B LAIT, L LIVINGSTON, J NEWMAN, P PUESCHEL, R RUSSELL, P SCHOEBERL, M TOON, G TRAUB, W VALERO, FPJ SELKIRK, H JORDAN, J AF TOON, O BROWELL, E GARY, B LAIT, L LIVINGSTON, J NEWMAN, P PUESCHEL, R RUSSELL, P SCHOEBERL, M TOON, G TRAUB, W VALERO, FPJ SELKIRK, H JORDAN, J TI HETEROGENEOUS REACTION PROBABILITIES, SOLUBILITIES, AND THE PHYSICAL STATE OF COLD VOLCANIC AEROSOLS SO SCIENCE LA English DT Article ID POLAR STRATOSPHERIC CLOUDS; ARCTIC WINTER STRATOSPHERE; SULFURIC-ACID; NITRIC-ACID; DROPLETS AB On 19 January 1992, heterogeneous loss of HNO3, ClNO3, and HCl was observed in part of the Mount Pinatubo volcanic cloud that had cooled as a result of forced ascent. Portions of the volcanic cloud froze near 191 kelvin. The reaction probability of ClNO3 and the solubility of HNO3 were close to laboratory measurements on liquid sulfuric acid. The magnitude of the observed loss of HCl suggests that it underwent a heterogeneous reaction. Such reactions could lead to substantial loss of HCl on background sulfuric acid particles and so be important for polar ozone loss. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. JET PROP LAB,PASADENA,CA 91109. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. SRI INT,MENLO PK,CA 94025. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. STERLING SOFTWARE INC,PALO ALTO,CA 94303. RP TOON, O (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 18 TC 35 Z9 35 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 27 PY 1993 VL 261 IS 5125 BP 1136 EP 1140 DI 10.1126/science.261.5125.1136 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU586 UT WOS:A1993LU58600022 PM 17790346 ER PT J AU WILSON, JC JONSSON, HH BROCK, CA TOOHEY, DW AVALLONE, LM BAUMGARDNER, D DYE, JE POOLE, LR WOODS, DC DECOURSEY, RJ OSBORN, M PITTS, MC KELLY, KK CHAN, KR FERRY, GV LOEWENSTEIN, M PODOLSKE, JR WEAVER, A AF WILSON, JC JONSSON, HH BROCK, CA TOOHEY, DW AVALLONE, LM BAUMGARDNER, D DYE, JE POOLE, LR WOODS, DC DECOURSEY, RJ OSBORN, M PITTS, MC KELLY, KK CHAN, KR FERRY, GV LOEWENSTEIN, M PODOLSKE, JR WEAVER, A TI IN-SITU OBSERVATIONS OF AEROSOL AND CHLORINE MONOXIDE AFTER THE 1991 ERUPTION OF MOUNT-PINATUBO - EFFECT OF REACTIONS ON SULFATE AEROSOL SO SCIENCE LA English DT Article ID EL-CHICHON; SIZE DISTRIBUTION; OZONE; STRATOSPHERE; N2O5; CHEMISTRY; LARAMIE; SUMMER; CLOUD; SO2 AB Highly resolved aerosol size distributions measured from high-altitude aircraft can be used to describe the effect of the 1991 eruption of Mount Pinatubo on the stratospheric aerosol. In some air masses, aerosol mass mixing ratios increased by factors exceeding 100 and aerosol surface area concentrations increased by factors of 30 or more. Increases in aerosol surface area concentration were accompanied by increases in chlorine monoxide at mid-latitudes when confounding factors were controlled. This observation supports the assertion that reactions occurring on the aerosol can increase the fraction of stratospheric chlorine that occurs in ozone-destroying forms. C1 UNIV CALIF IRVINE,DEPT GEOSCI,IRVINE,CA 92717. HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. SCI APPLICAT INT CORP,HAMPTON,VA 23666. NOAA,AERON LAB,BOULDER,CO 80303. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP WILSON, JC (reprint author), UNIV DENVER,DEPT ENGN,DENVER,CO 80208, USA. RI Brock, Charles/G-3406-2011; Toohey, Darin/A-4267-2008 OI Brock, Charles/0000-0002-4033-4668; Toohey, Darin/0000-0003-2853-1068 NR 27 TC 62 Z9 62 U1 2 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 27 PY 1993 VL 261 IS 5125 BP 1140 EP 1143 DI 10.1126/science.261.5125.1140 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU586 UT WOS:A1993LU58600023 PM 17790347 ER PT J AU NEWMAN, P LAIT, LR SCHOEBERL, M NASH, ER KELLY, K FAHEY, DW NAGATANI, R TOOHEY, D AVALLONE, L ANDERSON, J AF NEWMAN, P LAIT, LR SCHOEBERL, M NASH, ER KELLY, K FAHEY, DW NAGATANI, R TOOHEY, D AVALLONE, L ANDERSON, J TI STRATOSPHERIC METEOROLOGICAL CONDITIONS IN THE ARCTIC POLAR VORTEX, 1991 TO 1992 SO SCIENCE LA English DT Article ID AIR AB Stratospheric meteorological conditions during the Airborne Arctic Stratospheric Expedition II (AASE II) presented excellent observational opportunities from Bangor, Maine, because the polar vortex was located over southeastern Canada for significant periods during the 1991-1992 winter. Temperature analyses showed that nitric acid trihydrates (NAT temperatures below 195 k) should have formed over small regions in early December. The temperatures in the polar vortex warmed beyond NAT temperatures by late January (earlier than normal). Perturbed chemistry was found to be associated with these cold temperatures. C1 APPL RES CORP,LANDOVER,MD 20785. NOAA,AERON LAB,BOULDER,CO 80303. NATL METEOROL CTR,CTR CLIMATE ANAL,WASHINGTON,DC 20233. UNIV CALIF IRVINE,DEPT GEOSCI,IRVINE,CA 92717. HARVARD UNIV,ATMOSPHER RES PROJECT,ENGN SCI LAB,CAMBRIDGE,MA 02138. RP NEWMAN, P (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Toohey, Darin/A-4267-2008; Newman, Paul/D-6208-2012; Fahey, David/G-4499-2013 OI Toohey, Darin/0000-0003-2853-1068; Newman, Paul/0000-0003-1139-2508; Fahey, David/0000-0003-1720-0634 NR 27 TC 32 Z9 32 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 27 PY 1993 VL 261 IS 5125 BP 1143 EP 1146 DI 10.1126/science.261.5125.1143 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU586 UT WOS:A1993LU58600024 PM 17790348 ER PT J AU SALAWITCH, RJ WOFSY, SC GOTTLIEB, EW LAIT, LR NEWMAN, PA SCHOEBERL, MR LOEWENSTEIN, M PODOLSKE, JR STRAHAN, SE PROFFITT, MH WEBSTER, CR MAY, RD FAHEY, DW BAUMGARDNER, D DYE, JE WILSON, JC KELLY, KK ELKINS, JW CHAN, KR ANDERSON, JG AF SALAWITCH, RJ WOFSY, SC GOTTLIEB, EW LAIT, LR NEWMAN, PA SCHOEBERL, MR LOEWENSTEIN, M PODOLSKE, JR STRAHAN, SE PROFFITT, MH WEBSTER, CR MAY, RD FAHEY, DW BAUMGARDNER, D DYE, JE WILSON, JC KELLY, KK ELKINS, JW CHAN, KR ANDERSON, JG TI CHEMICAL LOSS OF OZONE IN THE ARCTIC POLAR VORTEX IN THE WINTER OF 1991-1992 SO SCIENCE LA English DT Article ID ANTARCTIC OZONE; STRATOSPHERIC CLOUDS; INSITU OBSERVATIONS; DEPLETION; CHLORINE; LATITUDE; HNO3; N2O5; TRENDS; CL2O2 AB In situ measurements of chlorine monoxide, bromine monoxide, and ozone are extrapolated globally, with the use of meteorological tracers, to infer the loss rates for ozone in the Arctic lower stratosphere during the Airborne Arctic Stratospheric Expedition II (AASE II) in the winter of 1991-1992. The analysis indicates removal of 15 to 20 percent of ambient ozone because of elevated concentrations of chlorine monoxide and bromine monoxide. Observations during AASE II define rates of removal of chlorine monoxide attributable to reaction with nitrogen dioxide (produced by photolysis of nitric acid) and to production of hydrochloric acid. Ozone loss ceased in March as concentrations of chlorine monoxide declined. Ozone losses could approach 50 percent if regeneration of nitrogen dioxide were inhibited by irreversible removal of nitrogen oxides (denitrification), as presently observed in the Antarctic, or without denitrification if inorganic chlorine concentrations were to double. C1 HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. JET PROP LAB,PASADENA,CA 91109. UNIV DENVER,DEPT ENGN,DENVER,CO 80208. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. NOAA,AERON LAB,BOULDER,CO 80303. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. RP SALAWITCH, RJ (reprint author), HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138, USA. RI Salawitch, Ross/B-4605-2009; Newman, Paul/D-6208-2012; Strahan, Susan/H-1965-2012; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Newman, Paul/0000-0003-1139-2508; Fahey, David/0000-0003-1720-0634 NR 54 TC 107 Z9 107 U1 1 U2 7 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 27 PY 1993 VL 261 IS 5125 BP 1146 EP 1149 DI 10.1126/science.261.5125.1146 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU586 UT WOS:A1993LU58600025 PM 17790349 ER PT J AU PROFFITT, MH AIKIN, K MARGITAN, JJ LOEWENSTEIN, M PODOLSKE, JR WEAVER, A CHAN, KR FAST, H ELKINS, JW AF PROFFITT, MH AIKIN, K MARGITAN, JJ LOEWENSTEIN, M PODOLSKE, JR WEAVER, A CHAN, KR FAST, H ELKINS, JW TI OZONE LOSS INSIDE THE NORTHERN POLAR VORTEX DURING THE 1991-1992 WINTER SO SCIENCE LA English DT Article ID INSITU ER-2 DATA; STRATOSPHERIC OZONE; ANTARCTIC VORTEX; NITROUS-OXIDE; DESTRUCTION; AIRCRAFT; TRENDS; HOLE; LATITUDE; EVOLUTION AB Measurements made in the outer ring of the northern polar vortex from October 1991 through March 1992 reveal an altitude-dependent change in ozone, with a decrease at the bottom of the vortex and a substantial increase at the highest altitudes accessible to measurement. The increase is the result of ozone-rich air entering the vortex, and the decrease reflects ozone loss accumulated after the descent of the air through high concentrations of reactive chlorine. The depleted air that is released out of the bottom of the vortex is sufficient to significantly reduce column ozone at mid-latitudes. C1 UNIV COLORADO,NOAA,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. JET PROP LAB,PASADENA,CA 91109. ATMOSPHER ENVIRONM SERV,DOWNSVIEW M3H 5T4,ON,CANADA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. RP PROFFITT, MH (reprint author), NOAA,AERON LAB,325 BROADWAY,BOULDER,CO 80303, USA. RI Aikin, Kenneth/I-1973-2013 NR 43 TC 97 Z9 97 U1 1 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 27 PY 1993 VL 261 IS 5125 BP 1150 EP 1154 DI 10.1126/science.261.5125.1150 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU586 UT WOS:A1993LU58600026 PM 17790350 ER PT J AU BROWELL, EV BUTLER, CF FENN, MA GRANT, WB ISMAIL, S SCHOEBERL, MR TOON, OB LOEWENSTEIN, M PODOLSKE, JR AF BROWELL, EV BUTLER, CF FENN, MA GRANT, WB ISMAIL, S SCHOEBERL, MR TOON, OB LOEWENSTEIN, M PODOLSKE, JR TI OZONE AND AEROSOL CHANGES DURING THE 1991-1992 AIRBORNE ARCTIC STRATOSPHERIC EXPEDITION SO SCIENCE LA English DT Article ID LIDAR OBSERVATIONS; PROFILES AB Stratospheric ozone and aerosol distributions were measured across the wintertime Arctic vortex from January to March 1992 with an airborne lidar system as part of the 1992 Airborne Arctic Stratospheric Expedition (AASE II). Aerosols from the Mount Pinatubo eruption were found outside and inside the vortex with distinctly different distributions that clearly identified the dynamics of the vortex. Changes in aerosols inside the vortex indicated advection of air from outside to inside the vortex below 16 kilometers. No polar stratospheric clouds were observed and no evidence was found for frozen volcanic aerosols inside the vortex. Between January and March, ozone depletion was observed inside the vortex from 14 to 20 kilometers with a maximum average loss of about 23 percent near 18 kilometers. C1 SCI APPLICAT INT CORP,HAMPTON,VA 23666. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BROWELL, EV (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. RI Grant, William/B-8311-2009 OI Grant, William/0000-0002-1439-3285 NR 15 TC 62 Z9 62 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 27 PY 1993 VL 261 IS 5125 BP 1155 EP 1158 DI 10.1126/science.261.5125.1155 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU586 UT WOS:A1993LU58600027 PM 17790351 ER PT J AU WHITING, GJ CHANTON, JP AF WHITING, GJ CHANTON, JP TI PRIMARY PRODUCTION CONTROL OF METHANE EMISSION FROM WETLANDS SO NATURE LA English DT Article ID CO2 EXCHANGE; SPARTINA-ALTERNIFLORA; BELOWGROUND BIOMASS; ARCTIC TUNDRA; RICE PADDIES; ATMOSPHERE; VEGETATION; TRANSPORT; SOIL; METHANOGENESIS AB WETLANDS, both natural and agricultural, contribute an estimated 40 to 50% of the total methane emitted to the atmosphere each year. Recent efforts in atmospheric modelling1 and attempts to constrain CH4 source strengths2 have indicated the need to delineate the processes responsible for the large variations in emission rates found within and across wetland types. Numerous biogeochemical factors are known to affect the activity of methanogenic bacteria3,4 and although there has been some success in relating water level5-7 and temperature8,9 to CH4 emissions within particular systems, these variables are insufficient for predicting emissions across a variety of wetlands2,10. From simultaneous measurements of CO2 and CH4 exchange in wetlands extending from subarctic peatlands to subtropical marshes, we report here a positive correlation between CH4 emission and net ecosystem production and suggest that net ecosystem production is a master variable, integrating many factors which control CH4 emission in vegetated wetlands. We find that about 3 per cent of the daily net ecosystem production is emitted back to the atmosphere as CH4. With projected stimulation of primary production and soil microbial activity in wetlands associated with elevated atmospheric CO2 concentrations11, we envisage the potential for increasing CH4 emissions from inundated wetlands, further enhancing the greenhouse effect. C1 NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23681. FLORIDA STATE UNIV,DEPT OCEANOG,TALLAHASSEE,FL 32306. NR 41 TC 424 Z9 454 U1 17 U2 167 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD AUG 26 PY 1993 VL 364 IS 6440 BP 794 EP 795 DI 10.1038/364794a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU581 UT WOS:A1993LU58100053 ER PT J AU CHENG, BL SCHRAMM, DN TRURAN, JW AF CHENG, BL SCHRAMM, DN TRURAN, JW TI A GENERAL COVARIANT JUMP CONDITION ACROSS A BUBBLE WALL AND THE QCD PHASE-TRANSITION SO PHYSICS LETTERS B LA English DT Article ID EXPANDING UNIVERSE; PRIMORDIAL NUCLEOSYNTHESIS; INFLATIONARY UNIVERSE; GAUGE-THEORIES; HADRON; SYMMETRY; VACUUM; TEMPERATURE; COLLISIONS; EXPANSION AB Covariant jump conditions across a bubble wall, including surface tension and dissipation, for a nongravitational moving surface have been derived. Special situations, such as those associated with a domain wall, a dust shell, and a spherical boundary, are discussed. In particular, the cosmological QCD phase transition has been examined as a specific application of the general formalism. The possible mechanism of energy transport during the phase transition is studied, and a critical condition for neutrino conduction to dominate over the hydrodynamic flow has been obtained. C1 UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP CHENG, BL (reprint author), UNIV ILLINOIS,DEPT ASTRON,1002 W GREEN ST,URBANA,IL 61801, USA. NR 48 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-2693 J9 PHYS LETT B JI Phys. Lett. B PD AUG 26 PY 1993 VL 313 IS 1-2 BP 15 EP 24 DI 10.1016/0370-2693(93)91184-O PG 10 WC Astronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LV189 UT WOS:A1993LV18900004 ER PT J AU BUTLER, BJ MUHLEMAN, DO SLADE, MA AF BUTLER, BJ MUHLEMAN, DO SLADE, MA TI MERCURY - FULL-DISK RADAR IMAGES AND THE DETECTION AND STABILITY OF ICE AT THE NORTH-POLE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID AMORPHOUS WATER ICE; COHERENT BACKSCATTER; MARS; ATMOSPHERE; SURFACE; VAPOR; TEMPERATURES; REFLECTIVITY; WAVELENGTHS; SATELLITES AB The first full-disk radar images of Mercury were obtained on August 8 and 23, 1991. These images were constructed using the Very Large Array (VLA) in Socorro, New Mexico, to receive and map radar flux at 3.5 cm (X band) which was continuously transmitted from the 70-m Jet Propulsion Laboratory/Deep Space Network antenna at Goldstone, California. Approximately 77% of the surface was imaged, at resolutions as good as 150 km. About half of the hemisphere photographed by Mariner 10 was imaged, as well as most of the hemisphere which has not previously been photographed. At the time of the observations, the north pole was visible, and the feature with the highest same sense (SS) circular reflectivity in the images is near the nominal polar position. The peak SS reflectivity of this feature was 7.9%, and the circular polarization ratio throughout much of the feature is > 1. Our best estimate of the size of the feature is that its diameter is less than or similar to 350 km. We interpret the feature to be indicative of the presence of ices because of the signal strength and polarization characteristics. The ices must be very clean and were thus probably deposited in a relatively short time period. The most likely place to find these ices is in any permanently shadowed areas in the polar regions, which would be very, cold. In comparison to absolute reflectivities of other icy bodies and regions in the solar system, the reflectivity of the north polar feature is slightly depressed. This is probably because the ices do not fill an observational resolution cell (i.e., there is incomplete areal coverage), or are covered by a layer of dust or soil, which absorbs some of the incoming and outgoing radar energy, or both. A covering layer would also protect any ices from erosion by energetic sources. Other prominent features on the unphotographed hemisphere correspond to positions where atmospheric sodium enhancements have been measured from Earth. This may indicate that these locations are large basins similar to the Caloris basin, where an atmospheric potassium enhancement has been measured, which may be the result of increased degassing in the disrupted surface and near surface. Direct comparison of the radar echoes from our features with those from the Caloris basin are hard to make, as Caloris was not imaged by us in a favorable geometry. Features on the photographed hemisphere are smaller and mostly associated with craters and crater complexes, most notably the Kuiper crater and its environs. C1 JET PROP LAB,PASADENA,CA 91109. RP BUTLER, BJ (reprint author), CALTECH,DEPT GEOL & PLANETARY SCI,PASADENA,CA 91125, USA. NR 89 TC 119 Z9 120 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1993 VL 98 IS E8 BP 15003 EP 15023 DI 10.1029/93JE01581 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LV631 UT WOS:A1993LV63100002 ER PT J AU PLESCIA, JB AF PLESCIA, JB TI WRINKLE RIDGES OF ARCADIA-PLANITIA, MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ORIGIN; TOPOGRAPHY; TECTONICS; PLANETS; ALBEDO; LUNAE; SYRIA AB Wrinkle ridges of Arcadia Planitia were examined to determine their morphology, spatial distribution, and the amount of crustal shortening and strain they accommodate. Ridges trend generally northward, but their orientation and distribution are strongly controlled by the relief of the underlying knobby material. Ridges begin or end at inselbergs of older terrain and are associated with buried craters. Arcadia Planitia ridges have an average width of 3425 m and accommodate an average folding shortening of 3 in and a faulting shortening of 55 m; mean total shortening is 57 m. Three east-west transects were constructed at 20-degrees 25-degrees, and 28-degrees-N to estimate regional shortening and strain. Average total shortening across the transects is about 900 m, corresponding to a regional compressive strain of 0.06%. The total shortening and compression across Arcadia Planitia are less than in Lunae Planum. Faults associated with the Arcadia ridges are inferred to have a westward dip compared with an eastward dip for Lunae Planum ridges. The generally levels of compression and symmetric orientation of the ridges suggest a regionally organized stress system. Differences in the shortening and strain between Lunae Planum and Arcadia Planitia may reflect the effects of local lithology or azimuthal variations in the stress field. RP PLESCIA, JB (reprint author), JET PROP LAB, DIV EARTH & SPACE SCI, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Plescia, Jeffrey/B-7738-2016 NR 30 TC 17 Z9 17 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1993 VL 98 IS E8 BP 15049 EP 15059 DI 10.1029/93JE01324 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LV631 UT WOS:A1993LV63100005 ER PT J AU RISSER, SM BERATAN, DN MARDER, SR AF RISSER, SM BERATAN, DN MARDER, SR TI STRUCTURE-FUNCTION-RELATIONSHIPS FOR BETA, THE 1ST MOLECULAR HYPERPOLARIZABILITY SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID NONLINEAR OPTICAL POLARIZABILITIES; STILBENE DERIVATIVES; SUSCEPTIBILITIES AB A four-orbital model is used to map the overall dependence of beta, the first electronic hyperpolarizability, on chemical parameters such as donor/acceptor strength and coupling between bridge and donor/acceptor orbitals. These calculations are used to develop general structure-property relationships for beta and to demonstrate the physical origin of maxima, minima, and zeros in beta. Comparison with multiorbital calculations on specific molecules show that the general relationships apply to more complex structures as well. A number of strategies for manipulating beta by varying molecular structure emerge from the analysis. We show that the absolute maxima in the beta surfaces fall outside of the range that has been probed using conventional organic donors and acceptors. C1 UNIV PITTSBURGH,DEPT CHEM,PITTSBURGH,PA 15260. JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. RI Beratan, David/C-5098-2011 NR 22 TC 80 Z9 81 U1 2 U2 7 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD AUG 25 PY 1993 VL 115 IS 17 BP 7719 EP 7728 DI 10.1021/ja00070a016 PG 10 WC Chemistry, Multidisciplinary SC Chemistry GA LW560 UT WOS:A1993LW56000016 ER PT J AU KOONTZ, SL CROSS, JB AF KOONTZ, SL CROSS, JB TI THE MATERIALS CHEMISTRY OF ATOMIC OXYGEN - LOW-EARTH-ORBIT AND THE LABORATORY SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LOS ALAMOS NATL LAB,CLS2,LOS ALAMOS,NM 87545. NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 22 PY 1993 VL 206 BP 55 EP IEC PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA LP321 UT WOS:A1993LP32101811 ER PT J AU VALENTIN, JR DAO, MD LE, DDQ PHILLIPS, JB ORENBERG, JB AF VALENTIN, JR DAO, MD LE, DDQ PHILLIPS, JB ORENBERG, JB TI THERMAL MODULATION CONCEPTS USED TO CHARACTERIZE CLAYS ACCORDING TO THEIR WATER-VAPOR ABSORPTION CHARACTERISTICS AND FOR THE TECHNIQUE OF HIGH-SPEED CHROMATOGRAPHY SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 SAN JOSE STATE UNIV,DEPT CHEM,SAN JOSE,CA 95192. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SO ILLINOIS UNIV,DEPT CHEM & BIOCHEM,CARBONDALE,IL 62901. SAN FRANCISCO STATE UNIV,DEPT CHEM,SAN FRANCISCO,CA 94132. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 22 PY 1993 VL 206 BP 60 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA LP321 UT WOS:A1993LP32100396 ER PT J AU TAN, KH HENNINGER, DL AF TAN, KH HENNINGER, DL TI MINERALOGY AND DECOMPOSITION OF LUNAR SIMULANTS BY HUMIC ACIDS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV GEORGIA,DEPT CROP & SOIL SCI,ATHENS,GA 30605. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 22 PY 1993 VL 206 BP 83 EP GEOC PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA LP321 UT WOS:A1993LP32101715 ER PT J AU WEIDNER, JW TIMMERMAN, P AF WEIDNER, JW TIMMERMAN, P TI THEORETICAL CHARGE DISCHARGE CURVES FOR THE NICKEL ELECTRODE SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV S CAROLINA,DEPT CHEM ENGN,COLUMBIA,SC 29208. JET PROP LAB,PASADENA,CA 91109. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 22 PY 1993 VL 206 BP 91 EP FUEL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA LP321 UT WOS:A1993LP32101606 ER PT J AU CONNELL, JW SMITH, JG HEDRICK, JL AF CONNELL, JW SMITH, JG HEDRICK, JL TI OXYGEN PLASMA RESISTANT PHENYL PHOSPHINE OXIDE-BASED POLY(ARYLENE ETHER)S CONTAINING HETEROCYCLIC UNITS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 22 PY 1993 VL 206 BP 144 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA LP322 UT WOS:A1993LP32201598 ER PT J AU ZEHE, MJ AF ZEHE, MJ TI TRENDS IN THE LEWIS ACID-BASE INTERACTIONS BETWEEN BORON HALIDES AND FLUORINATED DIETHYL ETHERS IN CRYOGENIC ARGON MATRICES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44142. CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 22 PY 1993 VL 206 BP 189 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA LP322 UT WOS:A1993LP32200941 ER PT J AU CAPLAN, ML STOAKLEY, DM STCLAIR, AK AF CAPLAN, ML STOAKLEY, DM STCLAIR, AK TI GOLD-DOPED POLYIMIDE FILMS FOR SPACE APPLICATIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 22 PY 1993 VL 206 BP 199 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA LP322 UT WOS:A1993LP32201651 ER PT J AU ECKLES, WE DURAJ, SA HEPP, AF FANWICK, PE AF ECKLES, WE DURAJ, SA HEPP, AF FANWICK, PE TI REACTIVITY OF THIOUREA TOWARDS ZERO-VALENT METALS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. NASA,LEWIS RES CTR,PHOTOVOLTAIC BRANCH,CLEVELAND,OH 44135. PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 22 PY 1993 VL 206 BP 430 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA LP321 UT WOS:A1993LP32102250 ER PT J AU BOWN, W MEHTA, R AF BOWN, W MEHTA, R TI THE SEAMY SIDE OF SWING BOWLING SO NEW SCIENTIST LA English DT Article C1 NASA,AMES RES CTR,FLUID MECH LAB,MOFFETT FIELD,CA 94035. RP BOWN, W (reprint author), STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305, USA. NR 1 TC 5 Z9 5 U1 0 U2 4 PU NEW SCIENTIST PUBL EXPEDITING INC PI ELMONT PA 200 MEACHAM AVE, ELMONT, NY 11003 SN 0262-4079 J9 NEW SCI JI New Sci. PD AUG 21 PY 1993 VL 139 IS 1887 BP 21 EP 24 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LU626 UT WOS:A1993LU62600033 ER PT J AU HAWLEY, JG TARG, R HENDERSON, SW HALE, CP KAVAYA, MJ MOERDER, D AF HAWLEY, JG TARG, R HENDERSON, SW HALE, CP KAVAYA, MJ MOERDER, D TI COHERENT LAUNCH-SITE ATMOSPHERIC WIND SOUNDER - THEORY AND EXPERIMENT SO APPLIED OPTICS LA English DT Article ID LASER-RADAR; PERFORMANCE AB The coherent launch-site atmospheric wind sounder (CLAWS) is a lidar atmospheric wind sensor designed to measure the winds above space launch facilities to an altitude of 20 km. In our development studies, lidar sensor requirements are defined, a system to meet those requirements is defined and built, and the concept is evaluated, with recommendations for the most feasible and cost-effective lidar system for use as an input to a guidance and control system for missile or spacecraft launches. The ability of CLAWS to meet NASA goals for increased safety and launch/mission flexibility is evaluated in a field test program at Kennedy Space Center (KSC) in which we investigate maximum detection range, refractive turbulence, and aerosol backscattering efficiency. The Nd:YAG coherent lidar operating at 1.06 mum with 1-J energy per pulse is able to make real-time measurements of the three-dimensional wind field at KSC to an altitude of 26 km, in good agreement with our performance simulations. It also shows the height and thickness of the volcanic layer caused by the volcanic eruption of Mount Pinatubo in the Philippines. C1 COHERENT TECHNOL INC, BOULDER, CO 80301 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. RP HAWLEY, JG (reprint author), LOCKHEED MISSILES & SPACE CO INC, PALO ALTO, CA 94304 USA. NR 20 TC 28 Z9 32 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1993 VL 32 IS 24 BP 4557 EP 4568 PG 12 WC Optics SC Optics GA LR786 UT WOS:A1993LR78600014 PM 20830118 ER PT J AU SUN, XL ABSHIRE, JB DAVIDSON, FM AF SUN, XL ABSHIRE, JB DAVIDSON, FM TI MULTISHOT LASER ALTIMETER - DESIGN AND PERFORMANCE SO APPLIED OPTICS LA English DT Article ID AVALANCHE AB The maximum measurement range of a laser altimeter can be extended by averaging the measurements from multiple laser shots at the same target. We present the principles of operation and design of such a multishot laser altimeter, which uses a Si avalanche photodiode detector. Aa an example, the performance of a spaceborne multishot altimeter containing components similar to those of the single-shot Mars Observer Laser Altimeter are given under operating conditions that would be encountered near Saturn. With 100-shot averages, we show that the multishot laser altimeter is capable of accurate ranging at fly-by distances of 10,000 km from an icy satellite. With 100-shot averages, the minimum optical signal level at a 90% correct-measurement probability under nighttime background is 9.8 detected signal photons per pulse as compared with 76 photons per pulse with a single shot. C1 NASA, GODDARD SPACE FLIGHT CTR, EXPTL INSTRUMENTAT BRANCH, GREENBELT, MD 20771 USA. RP SUN, XL (reprint author), JOHNS HOPKINS UNIV, DEPT ELECT & COMP ENGN, BALTIMORE, MD 21218 USA. RI Davidson, Frederic /A-3273-2010; Sun, Xiaoli/B-5120-2013; Abshire, James/I-2800-2013 NR 7 TC 0 Z9 1 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1993 VL 32 IS 24 BP 4578 EP 4585 PG 8 WC Optics SC Optics GA LR786 UT WOS:A1993LR78600016 PM 20830120 ER PT J AU MISHCHENKO, MI AF MISHCHENKO, MI TI LIGHT-SCATTERING BY SIZE SHAPE DISTRIBUTIONS OF RANDOMLY ORIENTED AXIALLY-SYMMETRICAL PARTICLES OF A SIZE COMPARABLE TO A WAVELENGTH SO APPLIED OPTICS LA English DT Article DE LIGHT SCATTERING; POLARIZATION; NONSPHERICAL PARTICLES; ENSEMBLE AVERAGING ID RADIATIVE-TRANSFER MODELS; POLARIZED-LIGHT; NONSPHERICAL PARTICLES; ELECTROMAGNETIC SCATTERING; T-MATRIX; ATMOSPHERE; ABSORPTION; SPHEROIDS; OBSERVABLES; RELEVANT AB The J-matrix method, as extended recently to randomly oriented scatterers [J. Opt. Soc. Am. A 8, 871 (1991)], is used to calculate rigorously light scattering by size-shape distributions of randomly oriented axially symmetric particles. The computational scheme is described in detail along with a newly developed convergence procedure that enables one to substantially reduce computer time and storage requirements. It is demonstrated that the elements of the Stokes scattering matrix for a power law size distribution of randomly oriented moderately aspherical spheroids are much smoother than and differ substantially from those of equivalent monodisperse spheroids, and thus averaging over orientations does not eliminate the necessity of averaging over particle sizes. Numerical calculations are reported for volume-equivalent polydispersions of spheres and size-shape distributions of moderately aspherical spheroids with the index of refraction 1.5 + 0.02 i, which is typical of some maritime aerosols. The angular-scattering behavior of the ensembles of nonspherical particles is found to be greatly different from that of the equivalent polydisperse spheres. The size-shape distributions of spheroids exhibit stronger side scattering near 120-degrees and weaker backscattering, the ratio F-22/F11 of the elements of the scattering matrix substantially deviates from unity, and the element F33 is greatly different from F44. For size distributions of oblate and prolate spheroids of the same aspect ratio, the ratios F-22/F11, F33/F11, and F34/F11 can differ substantially and, thus, are indicators of particle shape, whereas the angular patterns of the intensity (F11) and linear polarization (-F12/F11) are similar. For the size-shape distributions of moderately aspherical spheroids, the optical cross sections, the single-scattering albedo, and the asymmetry parameter of the phase function do not differ substantially from those of equivalent spheres. In general, the elements of the scattering matrix and optical cross sections are more shape dependent for larger particles. RP NASA, GODDARD INST SPACE STUDIES, HUGHES STX CORP, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Mishchenko, Michael/D-4426-2012 NR 51 TC 121 Z9 125 U1 1 U2 17 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 AUG 20 PY 1993 VL 32 IS 24 BP 4652 EP 4666 PG 15 WC Optics SC Optics GA LR786 UT WOS:A1993LR78600026 PM 20830130 ER PT J AU SERLEMITSOS, PJ LOEWENSTEIN, M MUSHOTZKY, RF MARSHALL, FE PETRE, R AF SERLEMITSOS, PJ LOEWENSTEIN, M MUSHOTZKY, RF MARSHALL, FE PETRE, R TI BROAD-BAND X-RAY TELESCOPE OBSERVATIONS OF THE HOT INTERSTELLAR MEDIA IN NGC-1399 AND NGC-4472 SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GALAXIES, ABUNDANCES; GALAXIES, INDIVIDUAL (NGC 1399, NGC4472); GALAXIES, STRUCTURE; GALAXIES, X-RAYS ID EARLY-TYPE GALAXIES; SURFACE-BRIGHTNESS FLUCTUATIONS; ELLIPTIC GALAXIES; FORNAX CLUSTER; ABUNDANCE; FLOWS; VIRGO; GAS AB We present our analysis and interpretation of spatially resolved X-ray spectroscopy of the elliptical galaxies NGC 1399 and NGC 4472 obtained with the Broad Band X-Ray Telescope. The X-ray emission from both galaxies is dominated by thermal emission from a hot interstellar medium. The temperature of the plasma in NGC 1399 is 1.0-1.2 keV with a mild positive temperature gradient; for NGC 4472 the average temperature is 0.7-1.0 keV. The temperature of NGC 1399, when combined with other X-ray and optical data, implies that, if the gas is gravitationally confined, approximately 70% of the mass inside a radius of almost-equal-to 86 (38 kpc) is nonluminous. The derived metallicities and metallicity gradients are consistent with optically determined stellar metallicities, and allow surprisingly small upper limits to be placed on Type la supernovae rates in both galaxies. The implications of this for the gasdynamical evolution of the two galaxies are discussed. Limits on the oxygen-to-iron ratio and the line-of-sight column density are derived. There is a possible detection of cold gas in the line of sight to NGC 1399 that exceeds the Galactic value. Constraints on the contribution from a harder spectral component are placed, and likely candidates for the origin of this secondary component are evaluated. RP SERLEMITSOS, PJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. NR 39 TC 53 Z9 53 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP 518 EP 530 DI 10.1086/173021 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT200 UT WOS:A1993LT20000007 ER PT J AU WALKER, TP STEIGMAN, G SCHRAMM, DN OLIVE, KA FIELDS, B AF WALKER, TP STEIGMAN, G SCHRAMM, DN OLIVE, KA FIELDS, B TI THE BORON-TO-BERYLLIUM RATIO IN HALO STARS - A SIGNATURE OF COSMIC-RAY NUCLEOSYNTHESIS IN THE EARLY GALAXY SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, HALO; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES; STARS, ABUNDANCES; STARS, POPULATION-II ID LITHIUM ISOTOPE RATIO; METAL-DEFICIENT STARS; BIG-BANG MODEL; OXYGEN ABUNDANCE; POOR STARS; ELEMENTS; LI; DWARFS; CONSEQUENCES; NUCLEI AB We discuss Galactic cosmic-ray (G-CR) spallation production of Li, Be, and B in the early Galaxy with particular attention to the uncertainties in the predictions of this model. The observed correlation between the Be abundance and the metallicity in metal-poor Population II stars requires that Be was synthesized in the early Galaxy. We show that the observations and such Population II GCR synthesis of Be are quantitatively consistent with the big bang nucleosynthesis production of Li-7. We find that there is a nearly model independent lower bound to B/Be of approximately 7 for GCR synthesis. Recent measurements of B/Be approximately 10 in HD 140283 are in excellent agreement with the predictions of Population II GCR nucleosynthesis. Measurements of the boron abundance in additional metal-poor halo stars is a key diagnostic of the GCR spallation mechanism. We also show that Population II CGR synthesis can produce amounts of Li-6 which may be observed in the hottest halo stars. C1 NASA,FNAL,FERMILAB ASTROPHYS GRP,BATIVA,IL 60510. UNIV MINNESOTA,DEPT PHYS & ASTRON,MINNEAPOLIS,MN 55455. UNIV CHICAGO,CHICAGO,IL 60637. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. RP WALKER, TP (reprint author), OHIO STATE UNIV,DEPT PHYS,COLUMBUS,OH 43210, USA. NR 51 TC 49 Z9 49 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP 562 EP 570 DI 10.1086/173025 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT200 UT WOS:A1993LT20000011 ER PT J AU PATEL, NA XIE, TL GOLDSMITH, PF AF PATEL, NA XIE, TL GOLDSMITH, PF TI COMETARY GLOBULES IN THE SOUTHEAST QUADRANT OF THE ROSETTE NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, INTERSTELLAR, LINES; H-II REGIONS; ISM, CLOUDS; ISM, INDIVIDUAL (NGC-2244); ISM, MOLECULES ID RADIATION-DRIVEN IMPLOSION; MOLECULAR CLOUDS; INTERSTELLAR CLOUDS; OB ASSOCIATIONS; CARBON-MONOXIDE; STAR FORMATION; MASSIVE STARS; POINT SOURCES; COMPLEX; PHOTOEVAPORATION AB We present a study of newly identified cometary globules in the southeast quadrant of the Rosette nebula using the J = 1-0 transition of carbon monoxide. The globules are found to be blueshifted by about 6 km s-1 with respect to the adjacent Rosette molecular cloud. The masses of the globules vary from 50 to 300 M., and their sizes are between 1 and 3 pc. Two of the globules have cometary morphology and show velocity gradients of approximately 1.5 km s-1 pc-1 along their symmetry axes. These globules are associated with the IRAS sources 06314+0421, X0632+043, 06322+0427, and 06327+0423 which coincide with local maxima in the (CO)-C-13 emission. The derived physical parameters of the globules are found to be consistent with those predicted by recent theoretical models of photoevaporating cometary clouds. We suggest that star formation induced by radiation driven implosion has occurred. C1 JET PROP LAB,PASADENA,CA 91109. RP PATEL, NA (reprint author), UNIV MASSACHUSETTS,FIVE COLL RADIO ASTRON OBSERV,DEPT PHYS & ASTRON,AMHERST,MA 01003, USA. RI Goldsmith, Paul/H-3159-2016 NR 54 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP 593 EP 603 DI 10.1086/173028 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT200 UT WOS:A1993LT20000014 ER PT J AU HILL, JK BOHLIN, RC CHENG, KP FANELLI, MN HINTZEN, P OCONNELL, RW ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP AF HILL, JK BOHLIN, RC CHENG, KP FANELLI, MN HINTZEN, P OCONNELL, RW ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP TI 30-DORADUS - ULTRAVIOLET AND OPTICAL STELLAR PHOTOMETRY SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; ISM, INDIVIDUAL (30 DORADUS); MAGELLANIC CLOUDS; TECHNIQUES, PHOTOMETRIC; ULTRAVIOLET, STARS ID LARGE MAGELLANIC CLOUD; HUBBLE-SPACE-TELESCOPE; IMAGING TELESCOPE; 30 DORADUS; STAR FORMATION; EXTINCTION; CAMERA AB Stellar photometry is presented for 314 stars in a 97 x 9.7 field in the 30 Dor nebula centered on R136. Magnitudes are computed from Ultraviolet Imaging Telescope images in up to 4 bands with effective wave-lengths from 1615 to 2558 A, and from a ground-based CCD image in the B band. Spectral types and extinctions are estimated using a least-squares technique, based on a spectrophotometric library compiled from IUE spectra. The fit spectral types agree to one library spectral type bin and two luminosity classes with types determined from optical slit spectra, for 34 of 39 non-WR stars. Approximately 35% of the 314 stars are fitted to main-sequence spectral types earlier than B1. Extinction of the more reddened stars in 30 Dor is shown to follow the Fitzpatrick 30 Dor extinction curve combined with a nebular curve of Fitzpatrick and Savage, where E(B-V) for each component is determined by the least-squares fit. Assuming a foreground extinction of E(B-V) = 0.10, average values of the color excess internal to 30 Dor are E(B-V)F = 0.11 +/- 0.03, from the Fitzpatrick 30 Dor extinction curve component, and E(B-V)FS = 0.17 +/- 0.17 from the Fitzpatrick and Savage nebular extinction curve component. Most stars within the high surface brightness area centered near R136 have low nebular extinction [E(B-V)FS < 0.03], while stars outside this area typically have E(B-V)FS < 0.30. Dust grains following the nebular extinction curve may have been expelled from the central regions of 30 Dor by stellar winds, or stars in the outer regions may be behind or within dust clouds. We also suggest that the difference between the Galactic extinction curve and the Fitzpatrick 30 Dor extinction curve may result from the lower cumulative nucleosynthesis in the LMC and the long time necessary for the component producing the local maximum at 2200 A (presumably carbon) to reach the interstellar medium in the form of grains. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,GSFC,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. CALIF STATE UNIV LONG BEACH,DEPT PHYS & ASTRON,LONG BEACH,CA 90840. UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. ASSOCIATED UNIV INC,NATL RADIO ASTRON OBSERV,NSF,CHARLOTTESVILLE,VA 22903. RP HILL, JK (reprint author), HUGHES STX,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 25 TC 17 Z9 17 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP 604 EP 610 DI 10.1086/173029 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT200 UT WOS:A1993LT20000015 ER PT J AU GREENHOUSE, MA FELDMAN, U SMITH, HA KLAPISCH, M BHATIA, AK BARSHALOM, A AF GREENHOUSE, MA FELDMAN, U SMITH, HA KLAPISCH, M BHATIA, AK BARSHALOM, A TI INFRARED CORONAL EMISSION-LINES AND THE POSSIBILITY OF THEIR LASER-EMISSION IN SEYFERT NUCLEI SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 SMITHSONIAN INST,NATL AIR & SPACE MUSEUM,ASTROPHYS LAB,WASHINGTON,DC 20560. USN,RES LAB,SOLAR TERR RELATIONSHIPS BRANCH,WASHINGTON,DC 20375. USN,RES LAB,ARTEP INC,WASHINGTON,DC 20375. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NUCL RES CTR NEGEV,IL-84190 BEER SHEVA,ISRAEL. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP 834 EP 835 PN 1 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT200 UT WOS:A1993LT20000038 ER PT J AU KEENAN, FP CONLON, ES BOWDEN, DA FEIBELMAN, WA PRADHAN, AK AF KEENAN, FP CONLON, ES BOWDEN, DA FEIBELMAN, WA PRADHAN, AK TI ELECTRON-DENSITY DIAGNOSTICS FOR GASEOUS NEBULAE INVOLVING THE O IV INTERCOMBINATION LINES NEAR 1400-A-ANGSTROM SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP 838 EP 838 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT200 UT WOS:A1993LT20000045 ER PT J AU KOUVELIOTOU, C MEEGAN, CA FISHMAN, GJ BHAT, NP BRIGGS, MS KOSHUT, TM PACIESAS, WS PENDLETON, GN AF KOUVELIOTOU, C MEEGAN, CA FISHMAN, GJ BHAT, NP BRIGGS, MS KOSHUT, TM PACIESAS, WS PENDLETON, GN TI IDENTIFICATION OF 2 CLASSES OF GAMMA-RAY BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS AB We have studied the duration distribution of the gamma-ray bursts of the first BATSE catalog. We find a bimodality in the distribution, which separates GRBs into two classes: short events (<2 s) and longer ones (>2 s). Both sets are distributed isotropically and inhomogeneously in the sky. We find that their durations are anticorrelated with their spectral hardness ratios: short GRBs are predominantly harder, and longer ones tend to be softer. Our results provide a first GRB classification scheme based on a combination of the GRB temporal and spectral properties. C1 UNIV SPACE RES ASSOCIAT,WASHINGTON,DC. UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. RP KOUVELIOTOU, C (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 16 TC 907 Z9 927 U1 0 U2 9 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP L101 EP L104 DI 10.1086/186969 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT202 UT WOS:A1993LT20200012 ER PT J AU PAN, XP SHAO, M COLAVITA, MM AF PAN, XP SHAO, M COLAVITA, MM TI HIGH ANGULAR RESOLUTION MEASUREMENTS OF ALGOL SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, VISUAL; INSTRUMENTATION, INTERFEROMETERS; STARS, INDIVIDUAL (BETA PERSEI) ID BETA-PERSEI; SYSTEM; STARS AB Algol (beta Per) is an extensively studied triple system which includes an eclipsing pair. Using long baseline optical interferometry, the AB-C system of Algol has had its geometric and physical parameters determined with higher resolution and accuracy than obtained with other techniques. The orbital elements are determined, without the use of spectroscopic data, as follows: P = 680.05d +/- 0.06d, T = JD 2,446,931.4 +/- 1.5, e = 0.225 +/- 0.005, a'' = 94.61 +/- 0.22 mas, i = 83.98-degrees +/- 0.09-degrees, omega = 310.29-degrees +/- 0.08-degrees, and OMEGA = 312.26-degrees + 0.13-degrees. The distance to Algol is determined as 28.2 +/- 0.8 pc. The absolute magnitude of the C component is 2.86 +/- 0.46 mag, and its mass is 1.50 +/- 0.11 M.. The observational results indicate the difference of the inclinations between the eclipsing pair and the wide pair to be within 1.6-degrees. For the first time, the eclipsing of the close pair was observed interferometrically, and the results compare well with those from photometry. We believe that the precise orbital parameters provide a good opportunity for comparison with the VLBI results at the milliarcsecond level and will lead to a good link between the optical and the radio reference frames. C1 JET PROP LAB,OPT SCI & APPLICAT SECT,PASADENA,CA 91109. RP PAN, XP (reprint author), CALTECH,DEPT ASTRON,105-24,PASADENA,CA 91125, USA. NR 20 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP L129 EP L131 DI 10.1086/186976 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT202 UT WOS:A1993LT20200019 ER PT J AU TAYLOR, M NELSON, MJ BLESS, RC DOLAN, JF ELLIOT, JL PERCIVAL, JW ROBINSON, EL VANCITTERS, GW AF TAYLOR, M NELSON, MJ BLESS, RC DOLAN, JF ELLIOT, JL PERCIVAL, JW ROBINSON, EL VANCITTERS, GW TI HIGH-SPEED ULTRAVIOLET PHOTOMETRY OF HD-60435 SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, INDIVIDUAL (HD-60435); STARS, OSCILLATIONS; STARS, PECULIAR ID OSCILLATING-AP STARS; SPECTRAL-ANALYSIS; TIME-SERIES; PECULIAR AB In this Letter, we present the first high-speed ultraviolet photometry of a oscillating Ap star, HD 60435. After removing known orbital effects related to the Hubble Space Telescope, we confirm the presence of a strong pulsation period at a frequency of 123.70 cycles per day. In addition, we find significant amplitude modulation of this frequency that we suggest could be the result of beating of multiple periodicities. In this context, we suggest evidence for the presence of four additional frequencies at nu = 120.56, 126.55, 149.49, and 221.03 cycles per day. Three of these frequencies correspond well to frequencies detected in optical observations of HD 60435. The fourth, at 149.49 cycles per day, if real, is a potentially new pulsation mode that has not been detected in ground-based observations of this star. The amplitude of the 123 cycles per day pulsation is significantly larger in the ultraviolet than it is in the blue. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. MIT,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02139. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. NATL SCI FDN,DIV ASTRON SCI,WASHINGTON,DC 20550. USN ACAD,DEPT AEROSP ENGN,ANNAPOLIS,MD 21402. RP TAYLOR, M (reprint author), UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706, USA. NR 11 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP L125 EP L128 DI 10.1086/186975 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT202 UT WOS:A1993LT20200018 ER PT J AU TSAI, JC AF TSAI, JC TI THE DARK-MATTER DISTRIBUTION OF M87 AND NGC 1399 SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GALAXIES, CLUSTERING; X-RAYS, GALAXIES ID COMA CLUSTER; GALAXIES; MASS; PHOTOMETRY; GALAXY-M87; NGC-1399 AB Recent X-ray observations of clusters of galaxies indicate that outside the innermost approximately 100 kpc region the ratio of dark matter density to baryonic matter density declines with radius. We show that this result is consistent with a cold dark matter simulation, suggesting the presence of dissipationless dark matter in the observed clusters. This is contrary to previous suggestions that dissipational baryonic dark matter is required to explain the decline in the density ratio. The simulation further shows that in the inner approximately 100 kpc region the density ratio should rise with radius. We confirm this property in M87 and NGC 1399, which are close enough to allow the determination of the density ratio in the required inner region. X-ray mappings of the dark matter distribution in clusters of galaxies are therefore consistent with the presence of dissipationless dark matter. RP TSAI, JC (reprint author), NASA,AMES RES CTR,MAIL STOP 245-3,MOFFETT FIELD,CA 94035, USA. NR 26 TC 11 Z9 11 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1993 VL 413 IS 2 BP L59 EP L62 DI 10.1086/186959 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LT202 UT WOS:A1993LT20200002 ER PT J AU LANGHOFF, SR BAUSCHLICHER, CW AF LANGHOFF, SR BAUSCHLICHER, CW TI A THEORETICAL-STUDY OF THE ELECTRIC-DIPOLE MOMENT FUNCTION OF SIO SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CONNECTED TRIPLE EXCITATIONS; LATE-TYPE STARS; ABINITIO CALCULATIONS; CONFIGURATION; CONVERGENCE; TRANSITION; MASERS; STATES AB A globally accurate electric dipole moment function (EDMF) is computed for the SiO molecule using large one-particle basis sets and an extensive treatment of electron correlation. A small translation of the EDMF brings the computed dipole moments for v=0-3 into good agreement with the highly accurate experimental values. The Einstein coefficients for the 1-0 fundamental and especially the 2-0 overtone band are significantly larger than the currently accepted values. Implications for astronomical measurements are discussed. RP LANGHOFF, SR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 37 TC 49 Z9 49 U1 0 U2 4 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 AUG 20 PY 1993 VL 211 IS 4-5 BP 305 EP 311 DI 10.1016/0009-2614(93)87064-A PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LT225 UT WOS:A1993LT22500004 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR AF BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR TI THEORETICAL-STUDY OF THE NO-B 4-SIGMA- AND O-2+ B 4-SIGMA-G- RADIATIVE LIFETIMES SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN-BASIS SETS; SYSTEM; ATOMS; COEFFICIENTS; 1ST-ROW AB We have computed the radiative lifetime of the NO b 4SIGMA- state, which is determined by the b 4SIGMA- -a 4PI Ogawa band system. Analogous calculations were carried out for the O2+ b 4SIGMA(g)- -a 4PI(u) first negative band system. Calibration calculations of both the one- and n-particle spaces are used to demonstrate that the theoretical lifetimes are accurate to 10%. The O2+ 4SIGMA(g)- radiative lifetimes are in excellent agreement with previous theoretical calculations and with the experimental values of Erman and Larsson. The theoretical NO b 4SIGMA- radiative lifetimes are consistent with our previous theoretical results, but significantly longer than the experimental values, suggesting that some decay mechanism other than the Ogawa system is contributing to the lifetime. RP BAUSCHLICHER, CW (reprint author), NASA,MOFFETT FIELD,CA 94035, USA. NR 21 TC 4 Z9 4 U1 0 U2 0 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 AUG 20 PY 1993 VL 211 IS 4-5 BP 312 EP 318 DI 10.1016/0009-2614(93)87065-B PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LT225 UT WOS:A1993LT22500005 ER PT J AU MONKS, PS STIEF, LJ KRAUSS, M KUO, SC KLEMM, RB AF MONKS, PS STIEF, LJ KRAUSS, M KUO, SC KLEMM, RB TI A DISCHARGE-FLOW PHOTOIONIZATION MASS-SPECTROMETRIC STUDY OF THE BRO (X2-PI) RADICAL - PHOTOIONIZATION SPECTRUM AND IONIZATION-ENERGY SO CHEMICAL PHYSICS LETTERS LA English DT Article ID COMPACT EFFECTIVE POTENTIALS; EXPONENT BASIS-SETS; KINETICS; OZONE; EFFICIENT; ATOMS; HBR AB The photoionization spectrum of BrO was measured over the wavelength range lambda = 106-122 nm using a discharge-flow photoionization mass spectrometer apparatus coupled to a synchrotron radiation source. BrO was generated by the reaction of O(3P) atoms with molecular bromine. A value of 10.46 +/- 0.02 eV was obtained for the adiabatic ionization energy of BrO from photoion thresholds, corresponding to the BrO+ (X 3SIGMA-)<--BrO(X 2PI3/2) transition. Spectra for both the (BrO)-Br-79 and (BrO)-Br-81 isotopes were very similar and the resultant photoion thresholds were identical, within experimental uncertainty. The structure observed in the spectra is discussed in terms of available states for BrO+, which have been calculated using MC-SCF methods. C1 CTR ADV RES BIOTECHNOL,ROCKVILLE,MD 20850. BROOKHAVEN NATL LAB,DEPT APPL SCI,UPTON,NY 11973. RP MONKS, PS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERRESTRIAL PHYS LAB,GREENBELT,MD 20771, USA. RI Monks, Paul/H-6468-2016 OI Monks, Paul/0000-0001-9984-4390 NR 16 TC 28 Z9 28 U1 0 U2 2 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 AUG 20 PY 1993 VL 211 IS 4-5 BP 416 EP 420 DI 10.1016/0009-2614(93)87083-F PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LT225 UT WOS:A1993LT22500023 ER PT J AU ERLANDSON, RE AGGSON, TL HOGEY, WR SLAVIN, JA AF ERLANDSON, RE AGGSON, TL HOGEY, WR SLAVIN, JA TI SIMULTANEOUS OBSERVATIONS OF SUBAURORAL ELECTRON-TEMPERATURE ENHANCEMENTS AND ELECTROMAGNETIC ION-CYCLOTRON WAVES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AURORAL RED ARCS; THERMAL ELECTRONS; MAGNETOSPHERE; PLASMAPAUSE; ACCELERATION; REGION AB Observational results from an investigation of low frequency (0.5-4.0 Hz) electromagnetic ion cyclotron waves and subauroral electron temperature enhancements recorded from the DE-2 satellite are presented. Four different wave events were analyzed, all recorded at magnetic latitudes from 57-60-degrees, magnetic local times from 8-14 hours, and altitudes from 600-900 km. The peak wave amplitudes during the events ranged from 870 nT and 5-30 mV/m in the magnetic and electric field, respectively. Electron temperature (T(e)) enhancements at the time of the waves were observed in 3 of 4 events. A linear relationship between the wave magnetic field spectral density and T(e) enhancements was found for these events. The T(e) enhancements were also correlated with an enhanced flux of low energy electrons. During one event (82104) an enhanced flux of electrons were observed at energies up to 50eV and at nearly all pitch angles, although the flux was largest in the precipitating and upflowing directions. It is suggested that the waves are responsible for heating the low energy electrons which precipitate to the ionosphere and produce the observed T(e) enhancements. The upflowing electron population appears to be heated at ionospheric altitudes, below the DE-2 satellite. The precipitating electrons may also be heated at ionospheric altitudes through Landau damping, although the observations do not rule out electron heating near the equator. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP ERLANDSON, RE (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20707, USA. RI Slavin, James/H-3170-2012; Erlandson, Robert/G-2767-2015 OI Slavin, James/0000-0002-9206-724X; NR 19 TC 16 Z9 16 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 20 PY 1993 VL 20 IS 16 BP 1723 EP 1726 DI 10.1029/93GL01975 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LU819 UT WOS:A1993LU81900015 ER PT J AU LOCKWOOD, M SMITH, MF AF LOCKWOOD, M SMITH, MF TI MAPPING THE DAYSIDE IONOSPHERE TO THE MAGNETOSPHERE ACCORDING TO PARTICLE-PRECIPITATION CHARACTERISTICS - COMMENT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CUSP C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP LOCKWOOD, M (reprint author), RUTHERFORD APPLETON LAB,DEPT SPACE SCI,DIDCOT OX11 0QX,OXON,ENGLAND. RI Lockwood, Mike/G-1030-2011 OI Lockwood, Mike/0000-0002-7397-2172 NR 10 TC 26 Z9 26 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 20 PY 1993 VL 20 IS 16 BP 1739 EP 1740 DI 10.1029/93GL01967 PG 2 WC Geosciences, Multidisciplinary SC Geology GA LU819 UT WOS:A1993LU81900019 ER PT J AU HASTENRATH, S DRUYAN, L AF HASTENRATH, S DRUYAN, L TI CIRCULATION ANOMALY MECHANISMS IN THE TROPICAL ATLANTIC SECTOR DURING THE NORTHEAST BRAZIL RAINY-SEASON - RESULTS FROM THE GISS GENERAL-CIRCULATION MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SURFACE-TEMPERATURE; RAINFALL; DYNAMICS; CLIMATE; IMPACT AB The role of the sea surface temperature (SST) pattern in the tropical Atlantic on the overlying atmosphere is studied from a 7-year run of the general circulation model (GCM) of the Goddard Institute for Space Studies (GISS) (period 1980-1986) and in comparison to upper air analyses of the European Centre for Medium-Range Weather Forecasts (ECMWF), surface ship observations of the SST and wind fields (COADS), and rainfall measurements in Northeast Brazil (Nordeste). Observations for March to April show that reduced northward SST decrease in the tropical Atlantic is accompanied by reduced northward decrease of lower-tropospheric thickness, which accounts for an inverse change in the meridional pressure gradient and reduced northerly wind component; this in turn entails a northward displaced Intertropical Convergence Zone and drought in the Nordeste. The GCM simulation reproduces the thermal and hydrostatic forcing of SST on the meridional gradients of lower-tropospheric thickness and pressure in the proper sense, albeit more weakly than observed. The modeled meridional wind component follows the meridional pressure gradient in the proper sense, but mean and range are smaller than observed, and the modeled interannual variability is not altogether consistent with observational evidence. The modeled March to April precipitation in the Nordeste shows little relation to the observed rainfall, although it is weakly related with the observed interhemispheric SST contrast and with the modeled near-surface meridional wind component. Both modeled and observed March to April Nordeste rainfall are negatively related with SST anomalies in the equatorial Pacific in March to April as well as in the immediately preceding January. Both in January and in March to April the modeled soil moisture exhibits a strong dependence on the modeled precipitation, but neither resembles in interannual variability nor in absolute amounts of the observed rainfall. Overall the GISS GCM seems to reproduce reasonably well the response of lower-tropospheric thickness and near-surface pressure to SST, while the simulation of wind and rainfall is somewhat deficient. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. COLUMBIA UNIV,NEW YORK,NY 10027. RP HASTENRATH, S (reprint author), UNIV WISCONSIN,DEPT METEOROL,MADISON,WI 53706, USA. NR 27 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1993 VL 98 IS D8 BP 14917 EP 14923 DI 10.1029/93JD01284 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LU595 UT WOS:A1993LU59500015 ER PT J AU PARRISH, DD HAHN, CJ WILLIAMS, EJ NORTON, RB FEHSENFELD, FC SINGH, HB SHETTER, JD GANDRUD, BW RIDLEY, BA AF PARRISH, DD HAHN, CJ WILLIAMS, EJ NORTON, RB FEHSENFELD, FC SINGH, HB SHETTER, JD GANDRUD, BW RIDLEY, BA TI INDICATIONS OF PHOTOCHEMICAL HISTORIES OF PACIFIC AIR MASSES FROM MEASUREMENTS OF ATMOSPHERIC TRACE SPECIES AT POINT-ARENA, CALIFORNIA - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Note ID HYDROCARBONS; TROPOSPHERE C1 NAT CTR ATMOSPHER RES,BOULDER,CO 80303. UNIV COLORADO,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. RP PARRISH, DD (reprint author), NOAA,AERON LAB,BOULDER,CO 80303, USA. RI Parrish, David/E-8957-2010; Fehsenfeld, Frederick/I-4876-2013 OI Parrish, David/0000-0001-6312-2724; NR 12 TC 36 Z9 36 U1 2 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1993 VL 98 IS D8 BP 14995 EP 14997 DI 10.1029/93JD01416 PG 3 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LU595 UT WOS:A1993LU59500021 ER PT J AU HIROI, T PIETERS, CM ZOLENSKY, ME LIPSCHUTZ, ME AF HIROI, T PIETERS, CM ZOLENSKY, ME LIPSCHUTZ, ME TI EVIDENCE OF THERMAL METAMORPHISM ON THE C-ASTEROID, G-ASTEROID, B-ASTEROID, AND F-ASTEROID SO SCIENCE LA English DT Article ID OUTER-BELT AB Reflectance spectra (0.3 to 2.6 micrometers) of 14 C, G, B, and F asteroids and 21 carbonaceous chondrite powders are compared in detail. Only three thermally metamorphosed CM-CI chondrites that have a weak ultraviolet absorption are shown to have close counterparts among those asteroids. Reflectance spectra of heated Murchison CM2 chondrite are compared with the average C and G type asteroid spectra. Murchison heated at 600-degrees to 1000-degrees-C exhibits a similar weak ultraviolet absorption and provides the best analog for those spectra. Comparison of ultraviolet absorption strengths between 160 C, G, B, and F asteroids and carbonaceous chondrites suggests that surface minerals of most of those asteroids are thermally metamorphosed at temperatures around 600-degrees to 1000-degrees-C. C1 BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. RP HIROI, T (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN3,HOUSTON,TX 77058, USA. NR 25 TC 98 Z9 99 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 20 PY 1993 VL 261 IS 5124 BP 1016 EP 1018 DI 10.1126/science.261.5124.1016 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LT747 UT WOS:A1993LT74700024 PM 17739619 ER PT J AU SIMONS, RN TAUB, SR AF SIMONS, RN TAUB, SR TI COPLANAR WAVE-GUIDE RADIAL LINE DOUBLE STUB AND APPLICATION TO FILTER CIRCUITS SO ELECTRONICS LETTERS LA English DT Article DE COPLANAR WAVE-GUIDE; LOWPASS FILTERS; RESONATORS AB Coplanar waveguide (CPW) and grounded coplanar waveguide (GCPW) radial line double stub resonators are experimentally characterised with respect to stub radius and sector angle. A simple closed-form design equation, which predicts the resonance radius of the stub, is presented. Use of a double stub resonator as a lowpass filter or as a harmonic suppression filter is demonstrated and design rules are given. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 3 TC 2 Z9 2 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD AUG 19 PY 1993 VL 29 IS 17 BP 1584 EP 1586 DI 10.1049/el:19931056 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA MG406 UT WOS:A1993MG40600059 ER PT J AU DEMORE, WB AF DEMORE, WB TI RATE-CONSTANT RATIO FOR THE REACTIONS OF OH WITH CH3D AND CH4 SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Letter AB The rate constant ratio and temperature dependence have been determined for the reactions of OH with CH3D and CH4. The compounds HFC-134a (CF3CFH2) and HCFC-141b(CH3CCl2F) were used as transfer standards, whereby the ratios k(CH3D)/k(134a) and k(CH3D)/k(141b) were measured as a function of temperature in the range 298-360 K. Combined with previous ratio measurements involving CH4, HFC-134a, and HCFC-141b, the results yield the (preferred) value k(CH3D)/k(CH4) = 1.10 exp(-75/T). The ratio at 298 K is 0.86. At 277 K, which is typical of the troposphere, the ratio is 0.84. Previous laboratory measurements of Gordon and Mulac,2 which seemed to suggest a much smaller ratio, are shown to be reconcilable with the present results by an alternative treatment of their data. The results of the present work are compatible with predictions based on correlations of OH abstraction rate constants with C-H and C-D bond energies and reaction exothermicities. RP DEMORE, WB (reprint author), JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. NR 9 TC 32 Z9 32 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD AUG 19 PY 1993 VL 97 IS 33 BP 8564 EP 8566 DI 10.1021/j100135a006 PG 3 WC Chemistry, Physical SC Chemistry GA LX144 UT WOS:A1993LX14400006 ER PT J AU LAHAV, O FABIAN, AC BARCONS, X BOLDT, E BUTCHER, J CARRERA, FJ JAHODA, K MIYAJI, T STEWART, GC WARWICK, RS AF LAHAV, O FABIAN, AC BARCONS, X BOLDT, E BUTCHER, J CARRERA, FJ JAHODA, K MIYAJI, T STEWART, GC WARWICK, RS TI A SIGNIFICANT CONTRIBUTION TO THE COSMIC X-RAY-BACKGROUND FROM SOURCES ASSOCIATED WITH NEARBY GALAXIES SO NATURE LA English DT Article ID IRAS GALAXIES; REDSHIFT SURVEY; ORIGIN; SAMPLE AB THE origin of the cosmic X-ray background remains a mystery after thirty years of study. The three properties of the background radiation commonly used for tackling this problem-its spectrum, isotropy and resolved component-are well defined by observations, but do not lead to a simple interpretation. A different approach to the problem1,2, in which fluctuations in the unresolved component are cross-correlated with galaxy catalogues, has led to the suggestion2 that as much as 60% of the background emission can be explained by a population of X-ray sources similar to present-day optically bright galaxies. Here we point out that such analyses must allow for contributions from X-ray sources which cluster with the galaxies, but do not necessarily have a counterpart in galaxy catalogues. For realistic assumptions about clustering, we obtain a revised limit on the local X-ray emissivity due to sources correlated with nearby galaxies. Extrapolating these results up to a redshift of approximately 5, we find that a smaller, but still significant, fraction of the X-ray background (30 +/- 15%) can be accounted for by these sources. To explain the residual background emissions, evolution of the source properties and/or a new population of sources at high redshift is required. C1 UNIV CANTABRIA, DEPT FIS MODERNA, E-39005 SANTANDER, SPAIN. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV LEICESTER, DEPT PHYS, X-RAY ASTRON GRP, LEICESTER LE1 7RH, ENGLAND. UCL, MULLARD SPACE SCI LAB, DORKING RH5 6NT, SURREY, ENGLAND. UNIV MARYLAND, DEPT ASTRON, COLL PK, MD 20742 USA. RP LAHAV, O (reprint author), UNIV CAMBRIDGE, INST ASTRON, MADINGLEY RD, CAMBRIDGE CB3 0HA, ENGLAND. RI Jahoda, Keith/D-5616-2012; Barcons, Xavier/L-3335-2014 OI Barcons, Xavier/0000-0003-1081-8861 NR 25 TC 35 Z9 35 U1 0 U2 0 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD AUG 19 PY 1993 VL 364 IS 6439 BP 693 EP 695 DI 10.1038/364693a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LT677 UT WOS:A1993LT67700048 ER PT J AU JAIN, RK FLOOD, DJ WEINBERG, I AF JAIN, RK FLOOD, DJ WEINBERG, I TI DIFFUSION LENGTH VARIATION AND PROTON DAMAGE COEFFICIENTS FOR INP/INXGA1-XAS/GAAS SOLAR-CELLS SO JOURNAL OF APPLIED PHYSICS LA English DT Note ID INP AB Indium phosphide solar cells are more radiation resistant than gallium arsenide and silicon solar cells and their growth by heteroepitaxy offers additional advantages leading to the development of lighter, mechanically strong and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5 and 3 MeV proton irradiations have been explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence has been calculated by simulating the cell performance. The diffusion length damage coefficient K(L) has also been plotted as a function of proton fluence. RP JAIN, RK (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 13 TC 4 Z9 4 U1 1 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD AUG 15 PY 1993 VL 74 IS 4 BP 2948 EP 2950 DI 10.1063/1.354600 PG 3 WC Physics, Applied SC Physics GA LT183 UT WOS:A1993LT18300119 ER PT J AU FRANCISCO, JS SANDER, SP AF FRANCISCO, JS SANDER, SP TI STRUCTURE AND THERMOCHEMISTRY OF CLO2 RADICALS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID QUADRATIC CONFIGURATION-INTERACTION; MOLLER-PLESSET PERTURBATION; LYING ELECTRONIC STATES; VIBRATIONAL FREQUENCIES; TRIPLE EXCITATIONS; MOLECULAR-ENERGIES; GAUSSIAN-1 THEORY; CHLORINE; OZONE AB The structure Of ClO2 has been calculated for the X2A'' ground state using unrestricted Hartree-Fock (UHF), unrestricted second-order Moller-Plesset perturbation (UMP2), configuration interaction using single and double excitation (CISD), and quadratic configuration interaction (QCI) ab initio molecular orbital methods. Calculations using UMP2 and CISD wave functions predict a CIO bond length of 1.728 +/- 0.01 angstrom. The single-configuration based QCI in the singles and doubles space with perturbation inclusion of triple substitutions, denoted QCISD(T), yield a ClO bond length of 2.205 angstrom. The QCI results are consistent with results of Jensen who showed that the CIO bond length is 2.181 angstrom using annihilated self-consistent methods (AUMP2). The thermochemistry Of ClO2 radical has been calculated using MP2 and QCI methods using an isodesmic scheme. Our scheme predicts the heat of formation for ClO2 at 0 K to be 24.6 +/- 2 kcal mol-1. C1 JET PROP LAB, PASADENA, CA 91109 USA. NR 50 TC 21 Z9 21 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD AUG 15 PY 1993 VL 99 IS 4 BP 2897 EP 2901 DI 10.1063/1.465197 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LR056 UT WOS:A1993LR05600061 ER PT J AU FREILICH, MH DUNBAR, RS AF FREILICH, MH DUNBAR, RS TI DERIVATION OF SATELLITE WIND MODEL FUNCTIONS USING OPERATIONAL SURFACE WIND ANALYSES - AN ALTIMETER EXAMPLE SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID NATIONAL-METEOROLOGICAL-CENTER; DATA ASSIMILATION; SPEED ALGORITHM; WAVE HEIGHT; BUOY DATA; VALIDATION; SCATTEROMETER; SCATTERING; STRESS AB One year of global surface wind products from multiple operational numerical weather prediction (NWP) forecast/analysis systems are used as comparison data to derive an empirical wind speed model function for the Geosat altimeter. The resulting model function is nearly identical to the modified Chelton-Wentz model for wind speeds from 4.5 to 15 m/s. The large quantity of comparison data at each wind speed allows detailed examination of the data scatter (and hence, model function uncertainty) as a function of wind speed. Highly skewed distributions at low wind speeds are consistent with specular reflections and antenna mispointing errors hypothesized by others on the basis of extremely limited data. Mesoscale variability in the wind field and synoptic scale errors in the NWP products are shown to account for approximately 30% of the observed scatter of sigma0 at each wind speed. The remaining scatter is largest at low winds, and decreases to a nearly constant value of approximately 12% at speeds greater than 7 m/s. Model function uncertainty expressed more traditionally in units of wind speed is examined for historical model functions as well as the present NWP-based model. The historical models have significant biases at high wind speeds owing to the lack of comparison in situ data used in their construction. Although the narrow swath, sensitivity to mispointing errors at low wind speeds, and small variation of backscatter with winds at high speeds limit the scientific utility of radar altimeter wind measurements, the present study demonstrates that modern operational NWP surface wind products are sufficiently accurate to allow development of fully empirical model functions and associated error analyses. C1 JET PROP LAB,PASADENA,CA 91109. RP FREILICH, MH (reprint author), OREGON STATE UNIV,COLL OCEAN & ATMOSPHER SCI,OCEANOG ADM BLDG 104,CORVALLIS,OR 97331, USA. NR 38 TC 42 Z9 42 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD AUG 15 PY 1993 VL 98 IS C8 BP 14633 EP 14649 DI 10.1029/93JC01183 PG 17 WC Oceanography SC Oceanography GA LU551 UT WOS:A1993LU55100020 ER PT J AU DILLARD, DA MCDANIELS, PR HINKLEY, JA AF DILLARD, DA MCDANIELS, PR HINKLEY, JA TI THE USE OF AN ECCENTRIC COMPRESSIVE LOAD TO AID IN PRECRACKING SINGLE-EDGE NOTCH BEND SPECIMENS SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article ID FRACTURE C1 NASA,LANGLEY RES CTR,MECH MAT BRANCH,POLYMER MAT BRANCH,HAMPTON,VA 23665. RP DILLARD, DA (reprint author), VIRGINIA POLYTECH INST & STATE UNIV,DEPT ENGN SCI & MECH,BLACKSBURG,VA 24061, USA. RI Dillard, David/C-3185-2012 OI Dillard, David/0000-0002-2903-9318 NR 5 TC 5 Z9 5 U1 0 U2 0 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0261-8028 J9 J MATER SCI LETT JI J. Mater. Sci. Lett. PD AUG 15 PY 1993 VL 12 IS 16 BP 1258 EP 1260 DI 10.1007/BF00506329 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA LU545 UT WOS:A1993LU54500010 ER PT J AU BELL, LD MANION, SJ HECHT, MH KAISER, WJ FATHAUER, RW MILLIKEN, AM AF BELL, LD MANION, SJ HECHT, MH KAISER, WJ FATHAUER, RW MILLIKEN, AM TI CHARACTERIZING HOT-CARRIER TRANSPORT IN SILICON HETEROSTRUCTURES WITH THE USE OF BALLISTIC-ELECTRON-EMISSION MICROSCOPY SO PHYSICAL REVIEW B LA English DT Note AB High-energy (0.1-1 eV) measurements of ballistic carrier transport in semiconductors have been performed using a new ballistic-electron-emission microscopy (BEEM) technique. Hot-electron attenuation lengths for p-type Si have been determined by combining precise Si molecular-beam-epitaxy methods with BEEM. A striking anomaly has been observed in the comparison of the 293- and 77-K results. RP BELL, LD (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 13 TC 33 Z9 33 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD AUG 15 PY 1993 VL 48 IS 8 BP 5712 EP 5715 DI 10.1103/PhysRevB.48.5712 PG 4 WC Physics, Condensed Matter SC Physics GA LV385 UT WOS:A1993LV38500093 ER PT J AU WILSON, LJ ADCOCK, LD PUSEY, ML AF WILSON, LJ ADCOCK, LD PUSEY, ML TI A DIALYSIS TECHNIQUE FOR DETERMINING AGGREGATE CONCENTRATIONS IN CRYSTALLIZING PROTEIN SOLUTIONS SO JOURNAL OF PHYSICS D-APPLIED PHYSICS LA English DT Article; Proceedings Paper CT 2ND INTERNATIONAL WORKSHOP ON THE CRYSTAL GROWTH OF ORGANIC MATERIALS ( CGOM-2 ) CY SEP 07-11, 1992 CL UNIV STRATHCLYDE, GLASGOW, SCOTLAND SP BRIT ASSOC CRYSTAL GROWTH, UNIV STRATHCLYDE, GLASGOW, EXXON CHEM, ICI, DUPONT CO, GLASGOW DEV AGCY, SHELL RES, HUBER, USA, EUROPEAN RES OFF HO UNIV STRATHCLYDE ID SELF-ASSOCIATION; LYSOZYME; KINETICS AB We have adapted a dialysis technique which provides aggregate concentrations of protein molecules in solutions which lead to crystal growth. In dialysis, the flux across a semipermeable membrane is directly proportional to the concentration of the diffusible solute inside the bag provided that the solute concentration in the bulk solution is infinitely dilute. Using membranes of varying porosity, the concentrations of different size solutes can be measured by measuring the flux rate across the membrane. We have used this technique to independently measure the concentrations of monomers, dimers, trimers and higher aggregates of lysozyme in both 1% NaCl and 3% NaCl (0.1 M NaAc, pH4) using 25 K and 50 K molecular weight cut-off membranes. We compare these concentration profiles with (110) face growth rate data under the same conditions. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP WILSON, LJ (reprint author), E TENNESSEE STATE UNIV,DEPT CHEM,JOHNSON CITY,TN 37614, USA. NR 21 TC 10 Z9 10 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0022-3727 J9 J PHYS D APPL PHYS JI J. Phys. D-Appl. Phys. PD AUG 14 PY 1993 VL 26 IS 8B BP B113 EP B117 DI 10.1088/0022-3727/26/8B/017 PG 5 WC Physics, Applied SC Physics GA LU341 UT WOS:A1993LU34100018 ER PT J AU WEISSMAN, P AF WEISSMAN, P TI COMETARY SCIENCE - FROZEN MYSTERIES SO NATURE LA English DT Editorial Material RP WEISSMAN, P (reprint author), JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD AUG 12 PY 1993 VL 364 IS 6438 BP 574 EP 576 DI 10.1038/364574a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LR771 UT WOS:A1993LR77100023 ER PT J AU COLGAN, SWJ HAAS, MR ERICKSON, EF RUBIN, RH SIMPSON, JP RUSSELL, RW AF COLGAN, SWJ HAAS, MR ERICKSON, EF RUBIN, RH SIMPSON, JP RUSSELL, RW TI DETECTION OF THE [N-II] 122 AND 205 MICRON LINES - DENSITIES IN G333.6-0.2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE H-II REGIONS; ISM, INDIVIDUAL (G333.6-0.2); INFRARED, INTERSTELLAR, CONTINUUM; INFRARED, INTERSTELLAR, LINES ID FAR-INFRARED LINE; PHOTODISSOCIATION REGIONS; EMISSION; ABUNDANCE; MODEL; ATMOSPHERES; ELEMENT; GAS AB We present measurements of the G333.6-0.2 H II region which include the first detection of the [N II] 122 mum forbidden line in an astronomical source and the first measurement of the [N II] 205 mum forbidden line in a discrete source. Eleven other fine structure lines of [S III], [Fe III], [Si II], [Ne III], [O III], [N III], [O I], and [C II] from 19 to 206 mum were also measured along with their adjacent continua. The 122 mum/205 mum flux ratio yields an electron density for the N+ zone of log N(e) = 2.5(+0.5/-0.4). From the [S III] (19 and 33 mum) and [O III] (52 and 88 mum) line pairs, the electron densities for the O++ and S++ zones are equal and higher than the N+ region, with log N(e) = 3.7 +/- 0.1. The density difference between the [O III]-[S III] and the [N II] emitting regions cannot persist for times comparable to the stellar evolution time scales without some regeneration mechanism for the inhomogeneities. The [N III] (57 mum) line suggests that the emitting mass in our beam is equally divided between the N+ and N++ regions, but we cannot determine a total nitrogen abundance because the [N ii] emission is likely to be more extended than our beam. From the [S III] to [O III] line flux ratio, we infer a stellar effective temperature of approximately 36,000 K for stellar atmospheres which roughly correspond to main-sequence stars. As with other H II regions of similar excitation, the theoretical stellar spectrum must be increased significantly at energies greater than the 41 eV ionization potential of Ne+ to produce the observed [Ne III] (36 mum) line flux. From the [O I] (63 and 145 mum) and [C II] (158 mum) line fluxes, and our measured infrared continuum luminosity of approximately 1.3 x 10(6) L., the density of the atomic gas adjacent to the ionized region is log N = 4.6. This implies that the ionized and neutral regions are in approximate pressure e librium. C1 UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. AEROSP CORP,CTR SPACE & ENVIRONM TECHNOL,LOS ANGELES,CA 90009. RP COLGAN, SWJ (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. RI Colgan, Sean/M-4742-2014 NR 38 TC 43 Z9 43 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1993 VL 413 IS 1 BP 237 EP 241 DI 10.1086/172991 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP771 UT WOS:A1993LP77100022 ER PT J AU RUBIN, RH DUFOUR, RJ WALTER, DK AF RUBIN, RH DUFOUR, RJ WALTER, DK TI SILICON AND CARBON ABUNDANCES IN THE ORION NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, ABUNDANCES; ISM, INDIVIDUAL (ORION NEBULA); ULTRAVIOLET, INTERSTELLAR ID EFFECTIVE COLLISION STRENGTHS; SI-III; C-III; RECOMBINATION COEFFICIENTS; GASEOUS NEBULAE; EXCITATION; EXTINCTION; EMISSION; LINES; IUE AB We assess the gas-phase abundances of Si and C from our recent measurements of Si++, C++, and C+ in the Orion Nebula by expanding on our earlier '' blister '' models. The C and Si abundances are derived from new IUE high-dispersion spectra of the C++ 1907, 1909 angstrom and Si++ 1883, 1892 angstrom lines and archival I UE data. Gas-phase Si/C = 0.016 in the Orion ionized volume and is particularly insensitive to uncertainties in extinction and temperature structure. The solar value is 0.098. Gas-phase C/H = 2.8 x 10(-4) and Si/H = 4.5 x 10(-6). Compared to solar, Si is depleted by a factor of approximately 8 in the ionized region, while C is much less depleted (factor of 1.3), if depleted at all. This suggests that most Si resides in dust grains even in the ionized volume. Thus, most of the observed [Si II] 34.8 mum emission in Orion does not arise in the H II region. C1 RICE UNIV,DEPT SPACE PHYS & ASTRON,HOUSTON,TX 77251. RP RUBIN, RH (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 44 TC 49 Z9 49 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1993 VL 413 IS 1 BP 242 EP 250 DI 10.1086/172992 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP771 UT WOS:A1993LP77100023 ER PT J AU BEATTY, JJ FICENEC, DJ TOBIAS, S MITCHELL, JW MCKEE, S NUTTER, S TARLE, G TOMASCH, A CLEM, J GUZIK, TG LIJOWSKI, M WEFEL, JP BOWER, CR HEINZ, RM MUFSON, SL MUSSER, J PITTS, JJ SPICZAK, GM AF BEATTY, JJ FICENEC, DJ TOBIAS, S MITCHELL, JW MCKEE, S NUTTER, S TARLE, G TOMASCH, A CLEM, J GUZIK, TG LIJOWSKI, M WEFEL, JP BOWER, CR HEINZ, RM MUFSON, SL MUSSER, J PITTS, JJ SPICZAK, GM TI THE COSMIC-RAY HE-3-HE-4 RATIO FROM 100 TO 1600 MEV AMU-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS; ACCELERATION OF PARTICLES; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES ID FRAGMENTATION CROSS-SECTIONS; ANTIPROTON PROTON RATIO; RELATIVISTIC NUCLEI; CARBON TARGETS; SOLAR MODULATION; HELIUM-ISOTOPES; HYDROGEN; SPECTRA; RADIATION; ABUNDANCE AB The Superconducting Magnet Instrument for Light Isotopes (SMILI) flew for 19 hours on 1989 September 1 with a residual overburden of 5 g cm-2. It measured the charge, rigidity, and velocity of 30,000 cosmic-ray helium nuclei, with velocity determined by time-of-flight and Cerenkov techniques. Using these data, the flux and isotopic composition of helium as a function of energy were determined. The observed isotopic composition is consistent with that expected from interstellar propagation models inferred from the secondaries of CNO, in contrast to earlier observations which indicated an overabundance of He-3. We discuss constraints that this result places on cosmic-ray transport and solar modulation models. C1 UNIV SPACE RES ASSOC,NASA,GSFC,GREENBELT,MD 20771. UNIV MICHIGAN,RANDALL LAB PHYS,DEPT PHYS,ANN ARBOR,MI 48109. LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803. INDIANA UNIV,DEPT PHYS & ASTRON,BLOOMINGTON,IN 47405. BOSTON UNIV,DEPT PHYS,BOSTON,MA 02215. RP BEATTY, JJ (reprint author), WASHINGTON UNIV,DEPT PHYS,ST LOUIS,MO 63130, USA. RI Beatty, James/D-9310-2011 OI Beatty, James/0000-0003-0481-4952 NR 31 TC 40 Z9 40 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1993 VL 413 IS 1 BP 268 EP 280 DI 10.1086/172994 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP771 UT WOS:A1993LP77100025 ER PT J AU BAND, D MATTESON, J FORD, L SCHAEFER, B PALMER, D TEEGARDEN, B CLINE, T BRIGGS, M PACIESAS, W PENDLETON, G FISHMAN, G KOUVELIOTOU, C MEEGAN, C WILSON, R LESTRADE, P AF BAND, D MATTESON, J FORD, L SCHAEFER, B PALMER, D TEEGARDEN, B CLINE, T BRIGGS, M PACIESAS, W PENDLETON, G FISHMAN, G KOUVELIOTOU, C MEEGAN, C WILSON, R LESTRADE, P TI BATSE OBSERVATIONS OF GAMMA-RAY BURST SPECTRA .1. SPECTRAL DIVERSITY SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS; RADIATION MECHANISMS, MISCELLANEOUS ID COMPTON-SCATTERING; BREAKS AB We studied the time-averaged gamma-ray burst spectra accumulated by the spectroscopy detectors of the Burst and Transient Source Experiment (BATSE). The spectra are described well at low energy by a power-law continuum with an exponential cutoff, N(E)(E) is-proportional-to E(alpha) exp (- E/E0), and by a steeper power law, N(E)(E) is-proportional-to E(beta) with alpha > beta, at high energy. However, the spectral parameters alpha, beta, and E0 vary from burst to burst with no universal values. The break in the spectrum, E0, ranges from below 100 keV to more than 1 MeV, but peaks below 200 keV with only a small fraction of the spectra breaking above 400 keV. Consequently, it is unlikely that a majority of the burst spectra are shaped directly by pair processes, unless bursts originate from a broad redshift range. We find that the correlations among burst parameters do not fulfill the predictions of the cosmological models of burst origin, but our burst sample may not be appropriate for such a test. No correlations with burst morphology or the spatial distribution were found. We also studied the process of fitting the BATSE spectral data. For example, we demonstrate the importance of using a complete spectral description even if a partial description (e.g., a model without a high-energy tail) is statistically satisfactory. C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MISSISSIPPI STATE UNIV,MISSISSIPPI STATE,MS 39762. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP BAND, D (reprint author), UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI 0111,LA JOLLA,CA 92093, USA. NR 36 TC 1433 Z9 1453 U1 7 U2 24 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1993 VL 413 IS 1 BP 281 EP 292 DI 10.1086/172995 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP771 UT WOS:A1993LP77100026 ER PT J AU HORACK, JM MEEGAN, CA FISHMAN, GJ WILSON, RB PACIESAS, WS EMSLIE, AG PENDLETON, GN BROCK, MN AF HORACK, JM MEEGAN, CA FISHMAN, GJ WILSON, RB PACIESAS, WS EMSLIE, AG PENDLETON, GN BROCK, MN TI EFFECTS OF LOCATION UNCERTAINTIES ON THE OBSERVED DISTRIBUTION OF GAMMA-RAY BURSTS DETECTED BY BATSE SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS ID GALACTIC HALO AB The Burst and Transient Source Experiment (BATSE) on NASA's Compton Gamma-Ray Observatory has shown that the sources of gamma-ray bursts have an angular distribution consistent with isotropy, yet the bursts are spatially inhomogeneous (Meegan et al.). Detection of a statistically significant deviation from isotropy in the burst distribution would provide a clue to the distance of the burst sources. BATSE's ability to detect slight deviations of the angular distribution from isotropy is, in part, dependent on the accuracy of the computed burst locations. Using bursts whose locations have been determined accurately and independently by the Third Interplanetary Network, we derive an estimate of the BATSE location uncertainties. We then incorporate these uncertainties into three-dimensional Monte Carlo simulations of the burst distributions to show that, despite individual burst location uncertainties of approximately 5-degrees, the ability of BATSE to place stringent limits on the anisotropy present in the angular distribution of the gamma-ray bursts is not significantly degraded. We conclude with a discussion of the effects on observations of possible galactic halo distributions of the burst sources. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. RP HORACK, JM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-66,HUNTSVILLE,AL 35812, USA. RI Horack, John/J-6670-2016 NR 19 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1993 VL 413 IS 1 BP 293 EP 297 DI 10.1086/172996 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP771 UT WOS:A1993LP77100027 ER PT J AU HORA, JL DEUTSCH, LK HOFFMANN, WF FAZIO, GG SHIVANANDAN, K AF HORA, JL DEUTSCH, LK HOFFMANN, WF FAZIO, GG SHIVANANDAN, K TI NEAR-INFRARED AND MIDINFRARED IMAGING OF THE PLANETARY-NEBULAE BD +30-DEGREES-3639 AND IC-418 SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; PLANETARY NEBULAE, INDIVIDUAL (BD + 30-DEGREES-3639, IC-418) ID POLYCYCLIC AROMATIC-HYDROCARBONS; EMISSION FEATURES; NEUTRAL HYDROGEN; SILICON-CARBIDE; DUST; CARBON; NGC-7027; GRAINS; STARS; SPECTROPHOTOMETRY AB We present near- and mid-infrared images of the planetary nebulae BD + 30-degrees-3639 and IC 418 with a unique combination of high spatial and spectral resolution. The mid-infrared images were obtained with MIRAC, a new IR array camera. For BD + 30-degrees-3639, the mid-IR images at 10.0, 11.2, 12.4, 12.8, and 13.2 mum have allowed us to separate the various spectral emission components such as the broad UIR features (perhaps from large molecular grains), the 12.8 mum [Ne II] emission feature, and continuum emission to determine the distribution of these components in the nebula. The derived temperature and opacity images show the detailed distribution of temperature and relative density of the dust. For IC 418, we have obtained high-resolution images in both the near- and mid-infrared. The images in the near-infrared at J, H, and K are important for determining the source of the IR excess; we have determined that one component of the excess is located near the central star and is possibly due to nonequilibrium heating of small grains. We have also imaged the halo emission at H and K, which has been detected in earlier studies, and have determined its spatial extent. The mid-IR images at 9.8 and 11.7 mum show continuum emission coincident with the ionized zone and suggest that silicon carbide emission originates from the region near the central star. C1 NASA,MOFFETT FIELD,CA 94035. UNIV CALIF BERKELEY,BERKELEY,CA 94720. STEWARD OBSERV,TUCSON,AZ 85721. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. GEN RES CORP,ARLINGTON,VA 22202. RP HORA, JL (reprint author), INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. OI Hora, Joseph/0000-0002-5599-4650 NR 51 TC 29 Z9 29 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1993 VL 413 IS 1 BP 304 EP 316 DI 10.1086/172998 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP771 UT WOS:A1993LP77100029 ER PT J AU FIERRO, JM BERTSCH, DL BRAZIER, KT CHIANG, J DAMICO, N FICHTEL, CE HARTMAN, RC HUNTER, SD JOHNSTON, S KANBACH, G KASPI, VM KNIFFEN, DA LIN, YC LYNE, AG MANCHESTER, RN MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL SCHNEID, E THOMPSON, DJ AF FIERRO, JM BERTSCH, DL BRAZIER, KT CHIANG, J DAMICO, N FICHTEL, CE HARTMAN, RC HUNTER, SD JOHNSTON, S KANBACH, G KASPI, VM KNIFFEN, DA LIN, YC LYNE, AG MANCHESTER, RN MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL SCHNEID, E THOMPSON, DJ TI PULSED HIGH-ENERGY GAMMA-RAYS FROM PSR-1055-52 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, OBSERVATIONS; PULSARS, INDIVIDUAL (PSR-1055-52) ID RADIO PULSARS; COS-B; PSR 1055-52; RADIATION; TELESCOPE; EMISSION; CRAB AB The Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray Observatory has detected a high-energy gamma-ray source at a position coincident with that of the radio pulsar PSR 1055-52. Analysis of the EGRET data at the radio pulsar period of 197 ms has revealed pulsed gamma-radiation at energies above 300 MeV, making PSR 1055-52 the fifth detected high-energy gamma-ray pulsar. The pulsed radiation from PSR 1055 - 52 has a very hard photon spectral index of -1.18 +/- 0.16 and a high efficiency for converting its rotational energy into gamma-rays. No unpulsed emission was observed. C1 MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. UNIV PALERMO,IST FIS,I-90134 PALERMO,ITALY. CNR,IST RADIOASTRON,I-40126 BOLOGNA,ITALY. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,JODRELL BANK,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. NASA,GODDARD SPACE FLIGHT CTR,COMPTON OBSERV SCI SUPPORT CTR,ASTRON PROGRAM,COMP SCI CORP,GREENBELT,MD 20771. RP FIERRO, JM (reprint author), STANFORD UNIV,WW HANSEN EXPTL PHYS LAB,STANFORD,CA 94305, USA. RI Nolan, Patrick/A-5582-2009; D'Amico, Nichi/A-5715-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 32 TC 92 Z9 92 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1993 VL 413 IS 1 BP L27 EP L30 DI 10.1086/186951 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP774 UT WOS:A1993LP77400007 ER PT J AU KETO, E BALL, R ARENS, J JERNIGAN, G MEIXNER, M SKINNER, C GRAHAM, J AF KETO, E BALL, R ARENS, J JERNIGAN, G MEIXNER, M SKINNER, C GRAHAM, J TI THE MIDINFRARED RADIO CORRELATION AT HIGH ANGULAR RESOLUTION - NGC-253 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-253); GALAXIES, STARBURST; INFRARED, GALAXIES ID STAR-FORMATION; SPIRAL GALAXIES; 10 MICRONS; EMISSION; NUCLEUS; REGIONS AB We present high angular resolution (1''.2), narrow-band (DELTAlambda/lambda = 0.1) images of the nucleus of NGC 253 at three wavelengths in the mid-infrared (8.5, 10.0, and 12.5 mum). We find that most of the mid-IR flux in the nucleus of NGC 253 derives from a very small region less-than-or-equal-to 120 pc in diameter. Within this small region there are three spatially and spectrally distinct IR components: two bright compact sources, and a surrounding envelope of low-level, diffuse emission. The mid-IR and 6 cm radio are loosely correlated in position but not in brightness. The implication is that the mid-IR-radio correlation may begin to break down on small spatial scales relevant to individual star-forming regions and large individual sources. These variations in the mid-IR spectra and in the radio-IR correlation imply that the nuclear emission is excited by more than one mechanism and source type. C1 UNIV HAWAII,NASA,INFRARED TELESCOPE FACIL,HONOLULU,HI 96822. LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94550. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. RP KETO, E (reprint author), LAWRENCE LIVERMORE NATL LAB,POB 808 L-59,LIVERMORE,CA 94550, USA. NR 32 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1993 VL 413 IS 1 BP L23 EP L26 DI 10.1086/186950 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP774 UT WOS:A1993LP77400006 ER PT J AU KOBAYASHI, R KOCH, H JORGENSEN, P LEE, TJ AF KOBAYASHI, R KOCH, H JORGENSEN, P LEE, TJ TI COMPARISON OF COUPLED-CLUSTER AND BRUECKNER COUPLED-CLUSTER CALCULATIONS OF MOLECULAR-PROPERTIES SO CHEMICAL PHYSICS LETTERS LA English DT Article ID ELECTRON CORRELATION; DIPOLE-MOMENT; HYPERPOLARIZABILITY DISPERSION; POLARIZABILITY FUNCTIONS; EXCITATION-ENERGIES; RESPONSE FUNCTIONS; LINEAR RESPONSE; WAVE-FUNCTION; NEON; CO AB The dipole moment, polarizabilities and hyperpolarizabilities of Ne, Be, BH, CH+, CO and NNO have been determined using the coupled-cluster and Brueckner coupled-cluster methods. The effect of orbital relaxation on these properties has been investigated implicitly, by carrying out singles and doubles coupled-cluster (CCSD) calculations with and without field relaxed SCF orbitals and explicitly through carrying out Brueckner doubles (BCCD) calculations. The effect of the connected triple excitations has been considered in the methods CCSD(T) and BCCD(T). The results show that allowing the SCF orbitals to relax in the presence of the field can make a significant difference to the CCSD properties. It has also been found that CCSD with field relaxed SCF orbitals and BCCD give similar results. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP KOBAYASHI, R (reprint author), AARHUS UNIV,DEPT CHEM,DK-8000 AARHUS,DENMARK. RI Koch, Henrik/J-2537-2012; Lee, Timothy/K-2838-2012; Jorgensen, Poul/J-2896-2016 OI Jorgensen, Poul/0000-0002-9785-7427 NR 46 TC 56 Z9 56 U1 1 U2 4 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 AUG 6 PY 1993 VL 211 IS 1 BP 94 EP 100 DI 10.1016/0009-2614(93)80057-V PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LQ146 UT WOS:A1993LQ14600016 ER PT J AU HUDER, K DEMORE, WB AF HUDER, K DEMORE, WB TI RATE-CONSTANT FOR THE REACTION OF OH WITH CH3CCL2F (HCFC-141B) DETERMINED BY RELATIVE RATE MEASUREMENTS WITH CH4 AND CH3CCL3 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ABSORPTION CROSS-SECTIONS; CH3CFCL2 AB Determination of accurate rate constants for OH abstraction is of great importance for the calculation of lifetimes for HCFCs and their impact on the atmosphere. For HCFC-141b there has been some disagreement in the literature for absolute measurements of this rate constant. In the present work rate constant ratios for HCFC-141b were measured at atmospheric pressure in the temperature range of 298-358K, with CH4 and CH3CCl3 as reference gases. Ozone was photolyzed at 254 nm in the presence of water vapor to produce OH radicals. Relative depletions of 141b and the reference gases were measured by FTIR. Arrhenius expressions for 141b were derived from each reference gas and found to be in good agreement with each other. The combined expression for HCFC-141b which we recommend is 1.4 x 10(-12) exp(-1630/T) with k at 298 K being 5.9 x 10(-15) cm3/molec-s. This value is in excellent agreement with the JPL 92-20 recommendation. RP HUDER, K (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 7 TC 13 Z9 13 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 6 PY 1993 VL 20 IS 15 BP 1575 EP 1577 DI 10.1029/93GL01766 PG 3 WC Geosciences, Multidisciplinary SC Geology GA LT387 UT WOS:A1993LT38700014 ER PT J AU BEZARD, B DEBERGH, C FEGLEY, B MAILLARD, JP CRISP, D OWEN, T POLLACK, JB GRINSPOON, D AF BEZARD, B DEBERGH, C FEGLEY, B MAILLARD, JP CRISP, D OWEN, T POLLACK, JB GRINSPOON, D TI THE ABUNDANCE OF SULFUR-DIOXIDE BELOW THE CLOUDS OF VENUS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VOLCANISM; SO2 AB We present a new method for determining the abundance of sulfur dioxide below the clouds of Venus. Absorption by the 3nu3 band of SO2 near 2.45 mum has been detected in high-resolution spectra of the night side of Venus recorded at the Canada-France-Hawaii telescope in 1989 and 1991. The inferred SO2 abundance is 130 +/- 40 ppm at all observed locations and pertains to the 35-45 km region. These values are comparable to those measured by the Pioneer Venus and Venera 11/12 entry probes in 1978. This stability stands in contrast to the apparent massive decrease in SO2 observed at the cloud tops since these space missions. These results are consistent with laboratory and modelling studies of the SO2 destruction rates in the lower atmosphere of Venus. The new spectroscopic technique presented here allows a remote monitoring of the SO2 abundance below the clouds, a likely tracer of Venusian volcanism. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130. JET PROP LAB,PASADENA,CA 91109. WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,ST LOUIS,MO 63130. UNIV COLORADO,BOULDER,CO 80309. INST ASTROPHYS,F-75014 PARIS,FRANCE. RP BEZARD, B (reprint author), OBSERV PARIS,DEPT RECH SPATIALE,SECT MEUDON,F-92195 MEUDON,FRANCE. NR 19 TC 39 Z9 39 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 6 PY 1993 VL 20 IS 15 BP 1587 EP 1590 DI 10.1029/93GL01338 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LT387 UT WOS:A1993LT38700017 ER PT J AU MOORE, JM EDGETT, KS AF MOORE, JM EDGETT, KS TI HELLAS-PLANITIA, MARS - SITE OF NET DUST EROSION AND IMPLICATIONS FOR THE NATURE OF BASIN FLOOR DEPOSITS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Hellas Planitia, located within an enclosed basin which includes the lowest topography on Mars, appears to be undergoing net erosion. Dust is removed from the basin. It probably contributes to global dust storms and should leave behind a coarse lag. The particle size distributions and probably the rock or boulder populations in this lag might be useful for distinguishing between processes which formed the lithologic units that comprise Hellas Planitia. This report concludes that the abundance of rock particles larger than coarse sand is very low. Although this hypothesis awaits confirmation from forthcoming spacecraft data, the origins for Hellas floor deposits favored by this study are indurated volcanic airfall or ancient loess, lacustrine deposits, and some types of volcanic mud flows. The conclusions of this study tend to disfavor such geologic processes as blocky lava flows, glacial deposits (e.g., moraines), or boulder-laden catastrophic flood outwash. C1 ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. NASA,AMES RES CTR,SETI INST,MOFFETT FIELD,CA 94035. RP MOORE, JM (reprint author), NASA,AMES RES CTR,CTR MARS EXPLORAT,MS 245-3,MOFFETT FIELD,CA 94035, USA. OI Edgett, Kenneth/0000-0001-7197-5751 NR 23 TC 18 Z9 18 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 6 PY 1993 VL 20 IS 15 BP 1599 EP 1602 DI 10.1029/93GL01302 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LT387 UT WOS:A1993LT38700020 ER PT J AU GONZALEZ, WD DEGONZALEZ, ALC TSURUTANI, BT AF GONZALEZ, WD DEGONZALEZ, ALC TSURUTANI, BT TI THE SEMIANNUAL VARIATION OF GREAT GEOMAGNETIC STORMS AND THE POSTSHOCK RUSSELL-MCPHERRON EFFECT PRECEDING CORONAL MASS EJECTA - COMMENT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Note ID MAGNETIC STORMS C1 INST NACL PESQUISAS ESPACIAIS,SAO PAULO,BRAZIL. NOAA,SEL,325 BROADWAY,BOULDER,CO 80303. JET PROP LAB,PASADENA,CA 91109. NR 9 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 6 PY 1993 VL 20 IS 15 BP 1659 EP 1660 DI 10.1029/93GL01588 PG 2 WC Geosciences, Multidisciplinary SC Geology GA LT387 UT WOS:A1993LT38700035 ER PT J AU CRUIKSHANK, DP ROUSH, TL OWEN, TC GEBALLE, TR DEBERGH, C SCHMITT, B BROWN, RH BARTHOLOMEW, MJ AF CRUIKSHANK, DP ROUSH, TL OWEN, TC GEBALLE, TR DEBERGH, C SCHMITT, B BROWN, RH BARTHOLOMEW, MJ TI ICES ON THE SURFACE OF TRITON SO SCIENCE LA English DT Article ID BIDIRECTIONAL REFLECTANCE SPECTROSCOPY; ATMOSPHERE; NEPTUNE; VOYAGER-2 AB The near-infrared spectrum of Triton reveals ices of nitrogen, methane, carbon monoxide, and carbon dioxide, of which nitrogen is the dominant component. Carbon dioxide ice may be spatially segregated from the other more volatile ices, covering about 10 percent of Triton's surface. The absence of ices of other hydrocarbons and nitriles challenges existing models of methane and nitrogen photochemistry on Triton. C1 SAN FRANCISCO STATE UNIV,DEPT GEOSCI,SAN FRANCISCO,CA 94132. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. JOINT ASTRON CTR,HILO,HI 96720. OBSERV PARIS,F-92195 MEUDON,FRANCE. LAB GLACIOL & GEOPHYS ENVIRONM,F-38402 ST MARTIN DHERES,FRANCE. JET PROP LAB,PASADENA,CA 91109. STERLING SOFTWARE INC,PALO ALTO,CA 94303. RP CRUIKSHANK, DP (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. RI Schmitt, Bernard/A-1064-2009 OI Schmitt, Bernard/0000-0002-1230-6627 NR 24 TC 171 Z9 171 U1 1 U2 13 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 6 PY 1993 VL 261 IS 5122 BP 742 EP 745 DI 10.1126/science.261.5122.742 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LQ730 UT WOS:A1993LQ73000033 PM 17757211 ER PT J AU OWEN, TC ROUSH, TL CRUIKSHANK, DP ELLIOT, JL YOUNG, LA DEBERGH, C SCHMITT, B GEBALLE, TR BROWN, RH BARTHOLOMEW, MJ AF OWEN, TC ROUSH, TL CRUIKSHANK, DP ELLIOT, JL YOUNG, LA DEBERGH, C SCHMITT, B GEBALLE, TR BROWN, RH BARTHOLOMEW, MJ TI SURFACE ICES AND THE ATMOSPHERIC COMPOSITION OF PLUTO SO SCIENCE LA English DT Article ID BIDIRECTIONAL REFLECTANCE SPECTROSCOPY; CHARON SYSTEM; WATER ICE; ULTRAVIOLET; DYNAMICS; NEPTUNE; TRITON; FROST AB Observations of the 1.4- to 2.4-micrometer spectrum of Pluto reveal absorptions of carbon monoxide and nitrogen ices and confirm the presence of solid methane. Frozen nitrogen is more abundant than the other two ices by a factor of about 50; gaseous nitrogen must therefore be the major atmospheric constituent. The absence of carbon dioxide absorptions is one of several differences between the spectra of Pluto and Triton in this region. Both worlds carry information about the composition of the solar nebula and the processes by which icy planetesimals formed. C1 SAN FRANCISCO STATE UNIV,DEPT GEOSCI,SAN FRANCISCO,CA 94132. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. OBSERV PARIS,F-92195 MEUDON,FRANCE. LAB GLACIOL & GEOPHYS ENVIRONM,F-38402 ST MARTIN DHERES,FRANCE. JET PROP LAB,PASADENA,CA 91109. STERLING SOFTWARE INC,PALO ALTO,CA 94303. RP OWEN, TC (reprint author), UNIV HAWAII,INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. RI Schmitt, Bernard/A-1064-2009 OI Schmitt, Bernard/0000-0002-1230-6627 NR 43 TC 214 Z9 214 U1 2 U2 15 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 6 PY 1993 VL 261 IS 5122 BP 745 EP 748 DI 10.1126/science.261.5122.745 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LQ730 UT WOS:A1993LQ73000034 PM 17757212 ER PT J AU DUXBURY, NS BROWN, RH AF DUXBURY, NS BROWN, RH TI THE PHASE-COMPOSITION OF TRITONS POLAR CAPS SO SCIENCE LA English DT Article ID NITROGEN; MODEL AB Triton's polar caps are modeled as permanent nitrogen deposits hundreds of meters thick. Complex temperature variations on Triton's surface induce reversible transitions between the cubic and hexagonal phases of solid nitrogen, often with two coexisting propagating transition fronts. Subsurface temperature distributions are calculated using a two-dimensional thermal model with phase changes. The phase changes fracture the upper nitrogen layer, increasing its reflectivity and thus offering an explanation for the surprisingly high southern polar cap albedo (approximately 0.8) seen during the Voyager 2 flyby. The model has other implications for the phase transition phenomena on Triton, such as a plausible mechanism for the origin of geyser-like plume vent areas and a mechanism of energy transport toward them. RP DUXBURY, NS (reprint author), JET PROP LAB,MS 183-501,4800 OAK GROVE,PASADENA,CA 91109, USA. NR 19 TC 14 Z9 14 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 6 PY 1993 VL 261 IS 5122 BP 748 EP 751 DI 10.1126/science.261.5122.748 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LQ730 UT WOS:A1993LQ73000035 PM 17757213 ER PT J AU TRYKA, KA BROWN, RH ANICICH, V CRUIKSHANK, DP OWEN, TC AF TRYKA, KA BROWN, RH ANICICH, V CRUIKSHANK, DP OWEN, TC TI SPECTROSCOPIC DETERMINATION OF THE PHASE-COMPOSITION AND TEMPERATURE OF NITROGEN ICE ON TRITON SO SCIENCE LA English DT Article ID REFLECTANCE SPECTROSCOPY AB Laboratory spectra of the first overtone band (2.1480 micrometers, 4655.4 reciprocal centimeters) of solid nitrogen show additional structure at 2.1618 micrometers (4625.8 reciprocal centimeters) over a limited temperature range. The spectrum of Neptune's satellite Triton shows the nitrogen overtone band as well as the temperature-sensitive component. The temperature dependence of this band may be used in conjunction with ground-based observations of Triton as an independent means of determining the temperature of surface deposits of nitrogen ice. The surface temperature of Triton is found to be 38.0(-1.0)+2.0 K, in agreement with previous temperature estimates and measurements. There is no spectral evidence for the presence of alpha-nitrogen on Triton's surface, indicating that there is less than 10 percent carbon monoxide in solid solution with the nitrogen on the surface. C1 JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP TRYKA, KA (reprint author), CALTECH,DEPT GEOL & PLANETARY SCI,PASADENA,CA 91125, USA. OI Tryka, Kimberly/0000-0002-5399-4235 NR 17 TC 38 Z9 38 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 6 PY 1993 VL 261 IS 5122 BP 751 EP 754 DI 10.1126/science.261.5122.751 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LQ730 UT WOS:A1993LQ73000036 PM 17757214 ER PT J AU GRIFFITH, CA AF GRIFFITH, CA TI EVIDENCE FOR SURFACE HETEROGENEITY ON TITAN SO NATURE LA English DT Article ID VOYAGER-1 RADIO-OCCULTATION; INFRARED OBSERVATIONS; ATMOSPHERE; AEROSOLS; OCEAN; MODEL AB UNLIKE all other planetary satellites, Saturn's moon Titan has a massive atmosphere1-8. At visible wavelengths, a thick stratospheric haze hides the surface from view. The emission from Titan in the infrared is largely from methane, nitrogen and hydrogen also in the stratosphere4. In the near-infrared, however, the extinction from haze decreases, and narrow windows exist in which the atmosphere absorbs only weakly9-14, and through which we might therefore catch a glimpse of the surface. Within two of these windows, Lemmon et al.15,16 recently observed a difference in Titan's albedo when the satellite was at eastern and western elongation with respect to Saturn. Although these observations could be taken to imply that Titan's surface is heterogeneous (and therefore is not covered by a global methane-ethane ocean as predicted previously7), they could also be explained by transient clouds. Here I present observations from two more rotational periods which record the same albedo difference, indicating that the heterogeneity is most unlikely to be associated with transient features and must be intrinsic to the surface. These results also imply that Titan is locked in a synchronous orbit about Saturn. RP GRIFFITH, CA (reprint author), NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 29 TC 68 Z9 68 U1 0 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD AUG 5 PY 1993 VL 364 IS 6437 BP 511 EP 514 DI 10.1038/364511a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LQ667 UT WOS:A1993LQ66700047 ER PT J AU TABIBAZAR, M KANG, S MACINNES, AN POWER, MB BARRON, AR JENKINS, PP HEPP, AF AF TABIBAZAR, M KANG, S MACINNES, AN POWER, MB BARRON, AR JENKINS, PP HEPP, AF TI ELECTRONIC PASSIVATION OF N-TYPE AND P-TYPE GAAS USING CHEMICAL-VAPOR-DEPOSITED GAS SO APPLIED PHYSICS LETTERS LA English DT Article ID SURFACES; OXIDE; BAND; BONDS AB We report on the electronic passivation of n- and p-type GaAs using chemical vapor deposited cubic GaS. Au/GaS/GaAs fabricated metal-insulator-semiconductor (MIS) structures exhibit classical high-frequency capacitor versus voltage (C-V) behavior with well-defined accumulation and inversion regions. Using high- and low-frequency C-V, the interface trap densities of approximately 10(11) eV-1 cm-2 on both n- and p-type GaAs are determined. The electronic condition of GaS/GaAs interface did not show any deterioration after a six week time period. C1 CASE WESTERN RESERVE UNIV,DEPT MAT ENGN & SCI,CLEVELAND,OH 44106. HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. GALLIA INC,WESTON,MA 02193. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP TABIBAZAR, M (reprint author), CASE WESTERN RESERVE UNIV,DEPT ELECT ENGN & APPL PHYS,CLEVELAND,OH 44106, USA. OI Barron, Andrew/0000-0002-2018-8288 NR 24 TC 43 Z9 43 U1 1 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD AUG 2 PY 1993 VL 63 IS 5 BP 625 EP 627 DI 10.1063/1.109970 PG 3 WC Physics, Applied SC Physics GA LQ133 UT WOS:A1993LQ13300020 ER PT J AU DAVIS, JR JENNINGS, RT BECK, BG AF DAVIS, JR JENNINGS, RT BECK, BG TI COMPARISON OF TREATMENT STRATEGIES FOR SPACE MOTION SICKNESS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION - SPACE BIOLOGY AND MEDICINE : EARTH ORBIT AND EXPLORATION MISSIONS CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB Treatment strategies for Space Motion Sickness (SMS) were compared using the results of postflight oral debriefings. Standardized questionnaires were administered to all crewmembers immediately following Space Shuttle flights by NASA flight surgeons. Cases of SMS were graded as mild, moderate, or severe based on published criteria, and medication effectiveness was judged based on subjective reports of symptom relief. Since October 1989, medication effectiveness is reported inflight through Private Medical Conferences with the crew. A symptom matrix was analyzed for 19 crewmembers treated with oral combination of scopolamine and dextroamphetamine (scopdex) and 15 crewmembers treated with promethazine delivered by intramuscular i.m. or suppository routes. Scopdex has been given preflight as prophylaxis for SMS, but analysis showed delayed symptom presentation in 9 crewmembers or failed to prevent symptoms in 7. Only 3 crewmembers who took scopdex had no symptoms inflight. Fourteen out of 15 crewmembers treated with i.m. promethazine and 6 of 8 treated with promethazine suppositories after symptom development had immediate (within 1-2 h) symptom relief and required no additional medication. There were no cases of delayed symptom presentation in the crewmembers treated with promethazine. This response is in contrast to untreated crewmembers who typically have slow symptom resolution over 72-96 h. We conclude that promethazine is an effective treatment of SMS symptoms inflight. NASA policy currently recommends treating crewmembers with SMS after symptom development, and no longer recommends prophylaxis with scopdex due to delayed symptom development and apparent variable absorption of oral medications during early flight days. RP DAVIS, JR (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77062, USA. NR 0 TC 9 Z9 9 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1993 VL 29 IS 8 BP 587 EP 591 DI 10.1016/0094-5765(93)90074-7 PG 5 WC Engineering, Aerospace SC Engineering GA LQ123 UT WOS:A1993LQ12300003 PM 11541638 ER PT J AU STEWART, DF LUJAN, BF AF STEWART, DF LUJAN, BF TI MEDICAL CONCERNS FOR EXPLORATION-CLASS MISSIONS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION - SPACE BIOLOGY AND MEDICINE : EARTH ORBIT AND EXPLORATION MISSIONS CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB The Space Exploration Initiative will challenge life scientists with a diverse set of crew medical risks. The varied sources of this cumulative risk are identified and briefly discussed in terms of fisk assessment and preliminary plans for risk management. The roles of Space Station Freedom and other flight programs are discussed in the context of exploration medical objectives; and the significant differences between Space Station era (second generation) and exploration medical support systems (third generation) are reviewed. RP STEWART, DF (reprint author), NASA HEADQUARTERS,AEROSP MED OFF,WASHINGTON,DC 20546, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1993 VL 29 IS 8 BP 633 EP 638 DI 10.1016/0094-5765(93)90081-7 PG 6 WC Engineering, Aerospace SC Engineering GA LQ123 UT WOS:A1993LQ12300010 PM 11541645 ER PT J AU LUJAN, BF AF LUJAN, BF TI SPACE BIOLOGY AND MEDICINE EARTH ORBIT AND EXPLORATION MISSIONS - SELECTED PAPERS PRESENTED AT THE 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION MONTREAL, CANADA, 7-11 OCTOBER 1991 SO ACTA ASTRONAUTICA LA English DT Editorial Material RP LUJAN, BF (reprint author), NASA,DIV LIFE SCI,CODE 5B,NASA HEADQUARTERS,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1993 VL 29 IS 8 BP R11 EP R11 DI 10.1016/0094-5765(93)90072-5 PG 1 WC Engineering, Aerospace SC Engineering GA LQ123 UT WOS:A1993LQ12300001 ER PT J AU STANSBERY, EG BOHANNON, G PITTS, C TRACY, T STANLEY, J AF STANSBERY, EG BOHANNON, G PITTS, C TRACY, T STANLEY, J TI RADAR OBSERVATIONS OF SMALL SPACE DEBRIS SO ADVANCES IN SPACE RESEARCH LA English DT Article AB This paper describes the collection and analysis of data on small space debris sensed by the Haystack radar and presents the results of measurements conducted between October 1990 and July 1992. The data are collected in the ''beam park'' mode of operation in which the radar stares in a fixed direction and debris randomly passes through the field-of-view. The analysis includes a description of the statistical' relationship between radar cross section (RCS) and physical size determined from separate, controlled tests. In addition, a computer model of the response of the Haystack radar while in beam park operation is used to calculate the probability of detection and effective detection area for all sizes and orbital inclinations of debris visible to the radar. C1 XONTECH INC,LOS ANGELES,CA 90045. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77258. RP STANSBERY, EG (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 2 TC 4 Z9 4 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 43 EP 48 DI 10.1016/0273-1177(93)90566-T PG 6 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600004 ER PT J AU ARNDT, GD FINK, P WARREN, WB AF ARNDT, GD FINK, P WARREN, WB TI A SPACE STATION-BASED ORBITAL DEBRIS TRACKING SYSTEM SO ADVANCES IN SPACE RESEARCH LA English DT Article AB Orbital debris with dimensions between 1 and 10 cm is an increasing threat to the Space Station Freedom. A possible solution is to track the debris with a station-based radar and passive IR sensors. Studies at JSC have shown that the approach window of the debris is relatively narrow, +/-10-degrees in elevation and +/- (30-degrees to 90-degrees) in azimuth. preliminary JSC studies suggest that angle and range accuracies of 10(-4) radians and 6 m are required for trajectory determination. Design considerations for minimizing the costs of a microwave array antenna are discussed. A proposed ground-based radar/antenna experiment for tracking small particles with high angular rates is described. C1 GBW RES INC,ATLANTA,GA. RP ARNDT, GD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 6 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 65 EP 68 DI 10.1016/0273-1177(93)90569-W PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600007 ER PT J AU ZOLENSKY, ME KINARD, WH AF ZOLENSKY, ME KINARD, WH TI RESULTS OF THE LDEF METEOROID AND DEBRIS SPECIAL INVESTIGATION GROUP SO ADVANCES IN SPACE RESEARCH LA English DT Article AB The Long Duration Exposure Facility was recovered in January, 1990, following 5.7 years of continuous exposure in low-Earth orbit. The gravity-stabilized nature of LDEF permits the resolution of the flux and trajectories of impacting meteoroids and spacecraft debris particulates. We have completed the collection of high-resolution, stereoscopic video imaging of all large impact features on the entire LDEF, and present here the preliminary results of our efforts to reduce these digitized images, and extract critical data. Contrary to our prior assumption, we find that impact craters in the T6 Al alloy are not paraboloid in cross section, but rather are better described by a 6th-order polynomial curve. We explore the implications of this discovery. We present results of detailed crater surveys of LDEF frame intercostal members, finding a unusual local variation in the impact frequency. In a discussion of impactor fluxes derived from LDEF results we explore apparent directionalities for impacting particulates which are not accounted for in current models. We briefly describe the special database designed and used by the M&D SIG. Finally, we present a list of recommendations for further LDEF analyses which will be necessary to ensure the safe design of spacecraft. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP ZOLENSKY, ME (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV SOLAR SYST EXPLORAT,HOUSTON,TX 77058, USA. NR 21 TC 5 Z9 5 U1 0 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 75 EP 85 DI 10.1016/0273-1177(93)90571-R PG 11 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600009 ER PT J AU OLIVER, JP WEINBERG, JL SINGER, SF SIMON, CG MULHOLLAND, JD COOKE, WJ WORTMAN, JJ KASSEL, PC AF OLIVER, JP WEINBERG, JL SINGER, SF SIMON, CG MULHOLLAND, JD COOKE, WJ WORTMAN, JJ KASSEL, PC TI ESTIMATION OF DEBRIS CLOUD TEMPORAL CHARACTERISTICS AND ORBITAL ELEMENTS SO ADVANCES IN SPACE RESEARCH LA English DT Article AB The Interplanetary Dust Experiment (IDE), one of the 56 experiments carried by LDEF, was, designed to detect impacts of extra-terrestrial particles and orbital debris. The IDE detectors (which covered about one square meter of the surface of LDEF) were sensitive to particles ranging in size from about 0.2 mum to 100 mum. The IDE experiment recorded the location in orbit and approximate origin direction for each impact. The resulting dataset represents perhaps the most extensive record ever gathered of the number and location of impacts due to small particles on a spacecraft in Earth orbit. The IDE dataset shows that impacts often occurred in ''bursts'' reoccurring each orbit. Such events, which we have designated Multiple orbit Events, can occur only if the impacting particles are in an Earth orbit that intersects that of LDEF. We have examined several such event sequences in the LDEF IDE dataset and have found orbital debris concentrations distributed in both moderate inclination (ca. 25-degrees-35-degrees) and high inclination (> 60-degrees) orbits. A peak flux of at least 12 impacts/second/sq. meter was detected in one such cloud. This is nearly 4 orders of magnitude above the mean flux observed over the LDEF 5.77 year mission duration. C1 LANGLEY RES CTR,HAMPTON,VA 23665. N CAROLINA STATE UNIV,RALEIGH,NC 27695. RP OLIVER, JP (reprint author), INST SPACE SCI & TECHNOL,GAINESVILLE,FL 32609, USA. NR 3 TC 1 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 103 EP 106 DI 10.1016/0273-1177(93)90573-T PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600011 ER PT J AU KESSLER, DJ AF KESSLER, DJ TI ORBITAL DEBRIS ENVIRONMENT IN LOW-EARTH-ORBIT - AN UPDATE SO ADVANCES IN SPACE RESEARCH LA English DT Article ID SPACECRAFT AB Until recently, the definition of the orbital debris environment depended upon mathematical models and limited data which had been obtained as a side product of other space related operations. Measurements conducted to specifically determine the orbital debris environment are now being conducted. These measurements are confirming the general trend of most earlier models are decreasing the uncertainty in how the number of Earth orbiting objects increases with decreasing size. The measurements are also providing data on the altitude and inclination distributions of smaller debris. Sufficient data now exist to remove some simplifying assumptions and update these earlier models. RP KESSLER, DJ (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 33 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 139 EP 148 DI 10.1016/0273-1177(93)90581-U PG 10 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600019 ER PT J AU ANZMEADOR, PD RAST, RH POTTER, AE AF ANZMEADOR, PD RAST, RH POTTER, AE TI APPARENT DENSITIES OF ORBITAL DEBRIS SO ADVANCES IN SPACE RESEARCH LA English DT Article AB Means and standard deviations of area-to-mass ratios for orbital debris tracked by US Space Command (USSPACECOM) were calculated from changes in apogee and perigee altitude due to atmospheric drag. Historical radar cross sections (RCSs) were analyzed to determine their means and standard deviations. These area-to-mass ratios and RCS-derived characteristic sizes were combined to produce statistical estimates of densities of the debris objects. Their mass densities and apparent densities were calculated based on observables and assumed shapes. C1 LOCKHEED ESC,HOUSTON,TX 77058. RP ANZMEADOR, PD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE SCI BRANCH,SN3,HOUSTON,TX 77058, USA. NR 5 TC 2 Z9 2 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 153 EP 156 DI 10.1016/0273-1177(93)90583-W PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600021 ER PT J AU CHRISTIANSEN, EL ROBINSON, JH CREWS, JL OLSEN, GD VILAS, F AF CHRISTIANSEN, EL ROBINSON, JH CREWS, JL OLSEN, GD VILAS, F TI SPACE STATION FREEDOM DEBRIS PROTECTION TECHNIQUES SO ADVANCES IN SPACE RESEARCH LA English DT Article AB This paper describes some of the strategies for protecting Space Station Freedom (SSF) from the consequences of meteoroid and orbital debris (M&D) impacts. The protection strategy involves a multifaceted which includes, among others, maneuvering SSF to avoid collisions with orbital debris tracked by the U.S. space surveillance network, and shielding critical SSF components from smaller meteoroid and debris particles that are not trackable. Additional methods employed to reduce M&D hazards include: optimizing the shielding weight distribution to compensate for the significant anisotropic M&D flux, locating shielded components strategically to increase shadowing, and providing operational procedures to minimize risks in the event of debris shield penetration (e.g. depressurize storage tanks when empty, close hatches to unoccupied modules, etc.). An integral part of M&D risk management for SSF will be a long-term commitment by NASA to monitor the debris environment over the entire SSF operational period accompanied by assessments of SSF protection system adequacy whenever the environment is updated. Combining these approaches will decrease risks from the M&D threat, thereby increasing crew safety and SSF mission success. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP CHRISTIANSEN, EL (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 22 TC 5 Z9 5 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 191 EP 200 DI 10.1016/0273-1177(93)90590-8 PG 10 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600028 ER PT J AU MCKNIGHT, D EDELSTEIN, K FUDGE, M AF MCKNIGHT, D EDELSTEIN, K FUDGE, M TI SPACE-SHUTTLE WINDOW IMPACT EVENTS STUDY SO ADVANCES IN SPACE RESEARCH LA English DT Article AB As of August 1992, more than 40 space shuttle missions have been completed. Impact features on the shuttle windows due to in-flight collisions with particulates were examined previously Absolute value of. This earlier analysis is augmented in this paper by additional data obtained over the last year and increased research efforts in the area of shuttle interaction with the space environment. Impact rates are scrutinized as a function of a variety of mission parameters such as year of mission, altitude, inclination, etc. Attempts to correlate a feature with either a natural or man-made impactor has been augmented by new hypervelocity lab data. This new data is presented, and its implications on this and previous studies are discussed. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP MCKNIGHT, D (reprint author), KAMAN SCI CORP,2560 HUNTINGTON AVE,ALEXANDRIA,VA 22303, USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 201 EP 204 DI 10.1016/0273-1177(93)90591-X PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600029 ER PT J AU FRIESEN, LJ KESSLER, DJ ZOOK, HA AF FRIESEN, LJ KESSLER, DJ ZOOK, HA TI REDUCED DEBRIS HAZARD RESULTING FROM A STABLE INCLINED GEOSYNCHRONOUS ORBIT SO ADVANCES IN SPACE RESEARCH LA English DT Article AB A stable geosynchronous orbit with an initial inclination of approximately 7.4-degrees will drastically reduce relative encounter velocities between objects in such an orbit, compared to relative velocities between objects in an initially equatorial geosynchronous orbit. Without north-south station keeping, the inclinations of objects placed into an equatorial geosynchronous orbit will increase to a maximum of 15-degrees, giving rise to encounter velocities of up to 800 meters/second. Collisions at these velocities are likely to produce fragments large enough to contribute to collisional cascading. However, the inclination of objects in the stable geosynchronous orbit will change very little, not only with respect to the equator, but also with respect to other objects in that orbit. Careful initial placement can limit collision velocities between objects in such an orbit to less than 5 meters/second. This reduced collision velocity is expected to reduce significantly or eliminate the production of debris fragments large enough to contribute to collisional cascading. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP FRIESEN, LJ (reprint author), LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058, USA. NR 8 TC 16 Z9 17 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 231 EP 241 DI 10.1016/0273-1177(93)90596-4 PG 11 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600034 ER PT J AU LOFTUS, JP ANZMEADOR, PD REYNOLDS, R AF LOFTUS, JP ANZMEADOR, PD REYNOLDS, R TI ORBITAL DEBRIS MINIMIZATION AND MITIGATION TECHNIQUES SO ADVANCES IN SPACE RESEARCH LA English DT Article AB Man's activity in space has generated significant amounts of debris that remain in orbit long enough to become a hazard to future space activities. Upper stages and spacecraft that have ended their functional life are the largest objects. In the past, additional debris has been generated by inadvertent explosions of upper stages and spacecraft, by intentional explosions for military reasons, and possibly by a few breakups resulting from collisions. In the future, debris can be generated by collisions among spa as the number of orbital objects continues to grow at a rate greater than the rate at which natural forces remove them from orbit. Some design and operations practices can minimize the inadvertent generation of debris, and others can remove objects from space at the end of their useful service, so they are not a source for the generation of future debris. Those studies are the primary concern of this paper. The issues are different in the low Earth orbits and in the geosynchronous orbits. In low Earth orbit, the hazards generated by potential collisions among spacecraft are severe because the events take place at such high velocities. In geosynchronous orbit, the collision consequence is not so seven because the relative velocities are low-less than 1 km/s. But because of the value of the limited arc and the extremely long lifetime of the satellites, debris generated in the orbit must be removed to a different orbit at the end of life if it is not to be a hazard to future operational spacecraft. The issue at present seems to be how high the reboost maneuver must be and what the system design and maneuver strategy should be to ensure effectiveness. The most economic removal of objects is achieved when those objects have the capability to execute the necessary maneuvers with their own systems and resources. The most costly option is to have some other system remove the object after it has become a derelict. Numerous options are being studied to develop systems and techniques that can remove objects from useful orbits at the end of their useful lift and do so for the least mass penalty and economic cost. RP LOFTUS, JP (reprint author), LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 33 TC 2 Z9 2 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD AUG PY 1993 VL 13 IS 8 BP 263 EP 282 DI 10.1016/0273-1177(93)90599-7 PG 20 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LQ666 UT WOS:A1993LQ66600037 ER PT J AU SCHILLING, LJ MACKALL, DA AF SCHILLING, LJ MACKALL, DA TI FLIGHT RESEARCH SIMULATION TAKES OFF SO AEROSPACE AMERICA LA English DT Article RP SCHILLING, LJ (reprint author), NASA,AMES DRYDEN RES FACIL,SYST ENGN BRANCH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD AUG PY 1993 VL 31 IS 8 BP 18 EP 21 PG 4 WC Engineering, Aerospace SC Engineering GA LP298 UT WOS:A1993LP29800006 ER PT J AU LOCK, JA HOVENAC, EA AF LOCK, JA HOVENAC, EA TI DIFFRACTION OF A GAUSSIAN-BEAM BY A SPHERICAL OBSTACLE SO AMERICAN JOURNAL OF PHYSICS LA English DT Article ID LORENZ-MIE THEORY; FRESNEL DIFFRACTION; SCATTERING; APPROXIMATION; LIGHT; WAVES AB The Kirchhoff integral for diffraction in the near-forward direction is derived from the exact solution of the electromagnetic boundary value problem of a focused Gaussian laser beam incident on a spherical particle. The diffracted intensity in the vicinity of the particle is computed and the way in which the features of the diffraction pattern depend on the width of the Gaussian beam is commented on. C1 NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135. RP LOCK, JA (reprint author), CLEVELAND STATE UNIV,DEPT PHYS,CLEVELAND,OH 44115, USA. NR 38 TC 18 Z9 18 U1 1 U2 6 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0002-9505 J9 AM J PHYS JI Am. J. Phys. PD AUG PY 1993 VL 61 IS 8 BP 698 EP 707 DI 10.1119/1.17440 PG 10 WC Education, Scientific Disciplines; Physics, Multidisciplinary SC Education & Educational Research; Physics GA LP005 UT WOS:A1993LP00500005 ER PT J AU CHIPMAN, RA BROWN, DM MCGUIRE, JP AF CHIPMAN, RA BROWN, DM MCGUIRE, JP TI POLARIZATION ABERRATION ANALYSIS OF THE ADVANCED X-RAY ASTROPHYSICS FACILITY TELESCOPE ASSEMBLY, (VOL 31, PG 2301, 1992) SO APPLIED OPTICS LA English DT Correction C1 JET PROP LAB, PASADENA, CA 91109 USA. TELEDYNE BROWN ENGN INC, HUNTSVILLE, AL 35899 USA. RP CHIPMAN, RA (reprint author), UNIV ALABAMA, DEPT PHYS, HUNTSVILLE, AL 35899 USA. NR 2 TC 3 Z9 3 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 1 PY 1993 VL 32 IS 22 BP 4236 EP 4237 PG 2 WC Optics SC Optics GA LP433 UT WOS:A1993LP43300025 PM 20830076 ER PT J AU BOTHUN, GD SCHOMBERT, JM IMPEY, CD SPRAYBERRY, D MCGAUGH, SS AF BOTHUN, GD SCHOMBERT, JM IMPEY, CD SPRAYBERRY, D MCGAUGH, SS TI THE SMALL-SCALE ENVIRONMENT OF LOW SURFACE BRIGHTNESS DISK GALAXIES SO ASTRONOMICAL JOURNAL LA English DT Article ID ELLIPTIC GALAXIES; REDSHIFT SURVEY; FAINT GALAXIES; STAR FORMATION; EVOLUTION; CLUSTERS; DWARF; MORPHOLOGY AB We use a sample of almost-equal-to low surface brightness (LSB) disk galaxies with measured redshifts in combination with the Center for Astrophysics redshift survey to test the hypothesis that LSB galaxies have a deficit of nearby companion galaxies compared to high surface brightness (HSB) disk galaxies. We find a very strong statistical deficit of galaxies located within a projected radius of 0.5 Mpc and within a velocity of 500 km s-1 around LSB disk galaxies compared to HSB ones. Further, comparing LSB and HSB disk galaxies which are located in the same portion of the sky indicates that the average distance to the nearest neighbor is 1.7 times farther for LSB disk galaxies. A Komologorov-Smirnoff test rules out, at greater than the 99% confidence level, the hypothesis that the distribution of nearest-neighbor distances is the same for HSB and LSB disk galaxies. We speculate that LSB disk galaxies have relatively long formation time scales and therefore must form in relative isolation. In addition, the lack of tidal interactions over a Hubble time serves to suppress the overall star-formation rate as no external trigger is available to help,clump the gas. The observed low surface densities of H I in combination with the low probability of tidal interactions effectively prevents these disk galaxies from evolving very rapidly. C1 CALTECH,IPAC,JPL,PASADENA,CA 91125. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. RP BOTHUN, GD (reprint author), UNIV OREGON,DEPT PHYS,EUGENE,OR 97403, USA. NR 42 TC 83 Z9 84 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1993 VL 106 IS 2 BP 530 EP 547 DI 10.1086/116659 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN790 UT WOS:A1993LN79000009 ER PT J AU PARKER, JW AF PARKER, JW TI THE OB ASSOCIATIONS OF 30 DORADUS IN THE LARGE MAGELLANIC CLOUD .1. STELLAR OBSERVATIONS AND DATA REDUCTIONS SO ASTRONOMICAL JOURNAL LA English DT Article ID WOLF-RAYET STARS; UPPER MAIN-SEQUENCE; SPECTRAL CLASSIFICATION; MASSIVE STARS; SPACE DISTRIBUTION; NEARBY GALAXIES; PHOTOMETRY; NEBULA; LMC; 30-DORADUS AB UBV photometry is presented for 2400 stars in the OB associations of 30 Doradus in the Large Magellanic Cloud, and I discuss new spectroscopic observations of 54 stars including 24 O stars. The CCD fields cover an area of 50 square arcminutes in the central region. The entire catalog (exclusive of the dense core cluster R 136) is photometrically complete to V = B = 18 mag and U = 17 mag, although the completeness magnitudes are fainter for regions with less nebular contamination. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NR 64 TC 97 Z9 97 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1993 VL 106 IS 2 BP 560 EP & DI 10.1086/116661 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN790 UT WOS:A1993LN79000011 ER PT J AU BROOKE, TY TOKUNAGA, AT STROM, SE AF BROOKE, TY TOKUNAGA, AT STROM, SE TI DUST EMISSION FEATURES IN 3 MU-M SPECTRA OF HERBIG AE/BE STARS SO ASTRONOMICAL JOURNAL LA English DT Article ID POLYCYCLIC AROMATIC-HYDROCARBONS; MAIN-SEQUENCE STARS; H-II REGIONS; VISUAL REFLECTION NEBULAE; INFRARED-EMISSION; MICRON EMISSION; YOUNG STARS; RESOLUTION SPECTRA; PLANETARY-NEBULAE; MOLECULAR CLOUDS AB Low and medium resolution spectra in the 3 mum region were obtained of 24 Herbig Ae/Be stars in a search for organic features from the dust around young stars. The 3.29 mum emission feature from aromatic hydrocarbons was detected for the first time in three objects, Lk Halpha 25, XY Per, and AS 310. The width of the feature in Lk Halpha 25 and XY Per corresponds to the narrow profile characteristic of material close to other young stellar objects. Two other stars, HD 245185 and HK Ori may have weak features. About 20% of the Herbig Ae/Be stars surveyed to date have firmly detected 3.29 mum features. Among these stars, the feature-to-continuum contrast varies over a wide range; emission equivalent widths vary by a factor approximately 20. The available data indicate that the 3.29 mum feature is more extended around Herbig Ae/Be stars of earlier spectral type, possibly due to dehydrogenization or destruction of the aromatics near these stars. Interpretation of the spectra in the optically thin limit suggests that the total number of aromatics excited by the stars is also greater around the earlier-type objects. The ratio of 3.29 mum feature flux to far-infrared flux, which is a measure of the abundance of aromatics relative to larger grains, shows less variation; however, there may be real abundance differences in some of the stars surveyed. If the small grains around Herbig Ae/Be stars have spectral properties like those seen in reflection nebulas, then they play a significant role in the total energy balance of these objects; they can radiate between 7% and 60% of the far-infrared luminosity. No other Herbig Ae/Be stars observed to date have the strong 3.42 and 3.53 mum features seen in Elias 1 and HD 97048. C1 JET PROP LAB, PASADENA, CA 91109 USA. UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. UNIV MASSACHUSETTS, FIVE COLL ASTRON DEPT, AMHERST, MA 01002 USA. NR 83 TC 56 Z9 56 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD AUG PY 1993 VL 106 IS 2 BP 656 EP 671 DI 10.1086/116672 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN790 UT WOS:A1993LN79000022 ER PT J AU PARMAR, AN ISRAEL, GL STELLA, L WHITE, NE AF PARMAR, AN ISRAEL, GL STELLA, L WHITE, NE TI THE X-RAY TIME VARIABILITY AND SPECTRUM OF GAMMA CASSIOPEIAE (X 0053+ 604) SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, INDIVIDUAL, GAMMA CAS; STARS, EMISSION-LINE BE; STARS, NEUTRON; X-RAYS, STARS ID EMISSION; BINARIES; PERSEI AB A 30 h duration EXOSAT observation made in 1985 December is used to examine the X-ray time variability and spectrum of the Be star gamma Cassiopeiae (X 0053 + 604). We find that the X-ray lightcurve is dominated by irregular energy-independent flaring on time-scales greater than or similar to 100 s. This flaring markedly decreases the sensitivity to any periodic signals. We find no evidence for the 6000 s oscillations reported by Frontera et al. (1987) from an earlier EXOSAT observation. We suggest that these arise from statistical fluctuations in the red noise power. The X-ray spectrum of gamma Cas can either be modeled by thermal emission from an optically thin plasma with a temperature of 12 keV, or by a cut-off power-law model with a narrow iron line at an energy of 6.67 keV. The origin of the X-ray emission in this system remains open since its spectral and temporal properties are consistent with both an accreting neutron star and a white dwarf while its high temperature argues against a coronal mechanism. C1 OSSERV ASTRON MERATE, I-20121 MILAN, ITALY. UNIV ROMA LA SAPIENZA, DIPARTIMENTO FIS, ICRA, I-00185 ROME, ITALY. NASA, GODDARD SPACE FLIGHT CTR, HEASARC, GREENBELT, MD 20771 USA. RP PARMAR, AN (reprint author), ESA, DEPT SPACE SCI, DIV ASTROPHYS, 2200 AG NOORDWIJK, NETHERLANDS. RI White, Nicholas/B-6428-2012; OI White, Nicholas/0000-0003-3853-3462; Israel, GianLuca/0000-0001-5480-6438 NR 32 TC 25 Z9 25 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 AUG PY 1993 VL 275 IS 1 BP 227 EP 235 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LR488 UT WOS:A1993LR48800026 ER PT J AU CATALA, C FOING, BH BAUDRAND, J CAO, H CHAR, S CHATZICHRISTOU, H CUBY, JG CZARNY, J DREUX, M FELENBOK, P FLOQUET, M GUERIN, J HUANG, L HUBERTDELPLACE, AM HUBERT, H HUOVELIN, J JANKOV, S JIANG, S LI, Q NEFF, JE PETROV, P SAVANOV, I SHCHERBAKOV, A SIMON, T TUOMINEN, I ZHAI, D AF CATALA, C FOING, BH BAUDRAND, J CAO, H CHAR, S CHATZICHRISTOU, H CUBY, JG CZARNY, J DREUX, M FELENBOK, P FLOQUET, M GUERIN, J HUANG, L HUBERTDELPLACE, AM HUBERT, H HUOVELIN, J JANKOV, S JIANG, S LI, Q NEFF, JE PETROV, P SAVANOV, I SHCHERBAKOV, A SIMON, T TUOMINEN, I ZHAI, D TI MULTISITE CONTINUOUS SPECTROSCOPY .1. OVERVIEW OF THE MUSICOS 1989 CAMPAIGN ORGANIZATION SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE METHODS, OBSERVATIONAL; TECHNIQUES, SPECTROSCOPIC; STARS, ACTIVITY; STARS, EMISSION LINE, BE; STARS, PRE-MAIN-SEQUENCE ID TERM SPECTRAL VARIABILITY; MAIN-SEQUENCE EVOLUTION; HERBIG AE STARS; AB-AURIGAE; ROTATION; CLUES; LINE; WIND AB We describe the organization of the multi-site spectroscopic MUSICOS 1989 campaign. This international campaign involved a large number of telescopes distributed around the world. In order to yield a complete time coverage, we had to transport two fiber-fed spectrographs, built at Paris-Meudon Observatory, to remote sites. Three scientific programs were followed during this campaign: 1) search for nonradial pulsations in the Be star 48 Per; 2) search for the signature of ''co-rotating interaction regions'' in the wind of the pre-main sequence Herbig Ae star AB Aur; 3) Doppler imaging and flare patrol for the RS CVn system HR 1099. The goal of the campaign was to provide a continuous coverage of these three targets in selected spectral lines. Programs 1 and 3 were successful, in the sense that the resulting duty cycle was over 80% for 48 Per and HR 1099. On the other hand, program 2 was unsuccessful, due to bad weather at most of the sites during the nights devoted to AB Aur. Although the initial goal of program 2 was not achieved, the observed spectra indicate an unusual activity level for AB Aur, and these results are presented here, while detailed analysis of the results of programs 1 and 3 will be published separately. C1 OBSERV PARIS, SECT MEUDON, CNRS, UNITE RECH 264, F-92195 MEUDON, FRANCE. INST ASTROPHYS SPATIALE, ORSAY, FRANCE. OBSERV PARIS, SECT MEUDON, RECH SPATIALE LAB, F-92195 MEUDON, FRANCE. OBSERV PARIS, SECT MEUDON, DEPT ASTROPHYS EXTRAGALACT & COSMOL, F-92195 MEUDON, FRANCE. OBSERV PARIS, SECT MEUDON, DEPT ASTROPHYS STELLAIRE & GALACT, F-92195 MEUDON, FRANCE. UNIV HELSINKI, SF-00100 HELSINKI 10, FINLAND. CRIMEAN ASTROPHYS OBSERV, CRIMEA, UKRAINE. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV HAWAII, HONOLULU, HI 96822 USA. RI Savanov, Igor/O-3318-2013 NR 27 TC 21 Z9 21 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 AUG PY 1993 VL 275 IS 1 BP 245 EP 255 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LR488 UT WOS:A1993LR48800029 ER PT J AU DAVID, LP SLYZ, A JONES, C FORMAN, W VRTILEK, SD ARNAUD, KA AF DAVID, LP SLYZ, A JONES, C FORMAN, W VRTILEK, SD ARNAUD, KA TI A CATALOG OF INTRACLUSTER GAS TEMPERATURES SO ASTROPHYSICAL JOURNAL LA English DT Article DE CATALOGS; GALAXIES, CLUSTERING; INTERGALACTIC MEDIUM; X-RAYS, GALAXIES ID X-RAY DATA; MEDIUM-SENSITIVITY SURVEY; LARGE-SCALE STRUCTURE; COLD DARK MATTER; GALAXY FORMATION; CLUSTERS; EVOLUTION; SAMPLE; MASS; EFFICIENCY AB We have searched the Einstein Monitor Proportional Counter (MPC) data base for observations of clusters of galaxies. The MPC was a nonfocal plane instrument on board the Einstein Observatory and accumulated data during all pointed observations with the four focal plane instruments. By co-adding the MPC spectra obtained during all pointed observations of clusters with IPC count rates greater than 0.1 counts per second, we have obtained sufficient photon statistics to estimate the X-ray temperature of 84 clusters. Combining the MPC results with EXOSAT and Ginga results reported in the literature yields a combined sample of 104 clusters with known X-ray temperatures. This is approximately twice as large as any previously published sample. One of the best studied X-ray correlations between clusters is that between their X-ray luminosity and gas temperature. We show that the best-fit power-law relation for our combined cluster sample can be explained by the observed increase in the gas-to-stellar mass ratio between low- and high-temperature clusters. There have been several recent reports in the literature concerning the evolution of X-ray luminous clusters at fairly low redshifts. The statistical significance of any evolution in our combined X-ray sample has been examined and compared with the statistical properties of clusters culled from optical catalogs. We find that there is strong evidence for a decrease in the X-ray luminosity of optically rich clusters beyond z almost-equal-to 0.06. This result is used to estimate the normalization of the primordial power spectrum of density fluctuations. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP DAVID, LP (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,SMITHSONIAN ASTROPHYS OBSERV,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 48 TC 451 Z9 452 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1993 VL 412 IS 2 BP 479 EP 488 DI 10.1086/172936 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN831 UT WOS:A1993LN83100003 ER PT J AU FRY, JN MELOTT, AL SHANDARIN, SF AF FRY, JN MELOTT, AL SHANDARIN, SF TI THE 3-POINT CORRELATION-FUNCTION IN AN ENSEMBLE OF 3-DIMENSIONAL SIMULATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE METHODS; NUMERICAL ID SHANE-WIRTANEN CATALOG; NUMERICAL SIMULATIONS; DENSITY-FLUCTUATIONS; EXPANDING UNIVERSE; GALAXIES; BISPECTRUM; SPECTRUM AB We evaluate the three-point function in Fourier space for an ensemble of three-dimensional 128(3) numerical simulations with initial power spectra characterized by spectral index n = +1, 0, -1, -2, -3, with no high-frequency cutoff and with cutoff k(c) = 16 or k(c) = 4. To remove dependences on scale and on time, we present results as the reduced amplitude Q in the hierarchical model as a function of the dimensionless variable kd(rms), where d(rms) is the mean square displacement of a particle from its initial position. For scale-free initial conditions, there is no evolution in Q. For initial conditions with a cutoff, Q evolves until the scale of the cutoff is in the nonlinear regime; the results afterwards are no different from those with no initial cutoff. We are able to follow, for the first time, the transition from quasi-linear to nonlinear regimes. In the quasi-linear regime, our results agree well with gravitational perturbation theory predictions, including a marked dependence on the shape of the configuration. In the nonlinear regime, the value of Q for scale-invariant initial conditions is remarkably independent of evolution epoch, of scale, and of configuration shape, and depends on spectral index roughly as Q = 3/(3 + n). C1 UNIV CAMBRIDGE,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. UNIV FLORIDA,DEPT PHYS,GAINESVILLE,FL 32611. UNIV KANSAS,DEPT PHYS & ASTRON,LAWRENCE,KS 66045. RP FRY, JN (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BOX 500,BATAVIA,IL 60510, USA. NR 25 TC 38 Z9 38 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1993 VL 412 IS 2 BP 504 EP 512 DI 10.1086/172938 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN831 UT WOS:A1993LN83100005 ER PT J AU CORCORAN, MF SWANK, JH SERLEMITSOS, PJ BOLDT, E PETRE, R MARSHALL, FE JAHODA, K MUSHOTZKY, R SZYMKOWIAK, A ARNAUD, K SMALE, AP WEAVER, K HOLT, SS AF CORCORAN, MF SWANK, JH SERLEMITSOS, PJ BOLDT, E PETRE, R MARSHALL, FE JAHODA, K MUSHOTZKY, R SZYMKOWIAK, A ARNAUD, K SMALE, AP WEAVER, K HOLT, SS TI BROAD-BAND X-RAY TELESCOPE SPECTROSCOPY OF ZETA-PUPPIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS; EARLY-TYPE, STARS; INDIVIDUAL (ZETA-PUPPIS), STARS; MASS LOSS, X-RAYS; STARS ID EARLY-TYPE STARS; OB SUPER-GIANTS; CROSS-SECTIONS; WINDS; ABSORPTION; VARIABILITY; EMISSION; MODELS; PROFILES AB The Broad-Band X-Ray Telescope (BBXRT) obtained moderate-resolution (approximately 90 eV) X-ray spectra of the 04 f star zeta Pup during the STS 35/Astro 1 mission in 1990 December. Despite the shortness of the observation (600 s), the data show a surprising amount of detail. We report the detection of an 0 absorption edge produced by ionized overlying wind material and K-shell line emission from Mg produced by a thermal plasma of temperature near 6 x 10(6) K. The data are used to place constraints on the location, temperature, and amount of the X-ray-emitting gas, as well as the abundance and ionization of the wind material. C1 UNIV SPACE RES ASS,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MARYLAND,ASTRON PROGRAM,COLL PK,MD 20742. RP CORCORAN, MF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Jahoda, Keith/D-5616-2012; Swank, Jean/F-2693-2012 NR 29 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1993 VL 412 IS 2 BP 792 EP 796 DI 10.1086/172961 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN831 UT WOS:A1993LN83100028 ER PT J AU PARSONS, SB AKE, TB AF PARSONS, SB AKE, TB TI ULTRAVIOLET AND OPTICAL STUDIES OF BINARIES WITH LUMINOUS COOL PRIMARIES AND HOT COMPANIONS .4. FURTHER IUE DETECTIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, SPECTROSCOPIC; ULTRAVIOLET, STARS ID SPECTRAL CLASSIFICATION; STARS; SUPERGIANTS; DUST AB We have obtained IUE spectra for 31 middle and late-type giant and supergiant stars whose TD-1 fluxes or ground-based spectra indicate the presence of a hot component, or whose radial velocities indicate an unseen component. Stellar components earlier than type Fl were detected in 22 cases. While 20 of the hot secondaries are seen weakly in optical spectra, two are UV discoveries: HD 58134 and HD 183864. The hot companions are classified accurately by temperature class from their far-UV spectra. The interstellar extinction of each system and the relative luminosities of the components are derived from the UV and optical fluxes, using a new grid of UV intrinsic colors for hot dwarfs. We find that many giant stars apparently have companions which are too hot and hence too luminous for consistency with the primary's spectral classification. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. COMP SCI CORP,ASTRON PROGRAMS,GHRS SCI SUPPORT CTR,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP PARSONS, SB (reprint author), COMP SCI CORP,ASTRON PROGRAMS,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. NR 40 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1993 VL 412 IS 2 BP 814 EP 826 DI 10.1086/172964 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN831 UT WOS:A1993LN83100031 ER PT J AU GURMAN, JB AF GURMAN, JB TI THE SUNSPOT TRANSITION REGION - WHERE ARE THE BRIGHT PLUMES AND THE DOWNFLOWS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, ATMOSPHERE; SUN, TRANSITION REGION; SUNSPOTS ID ENERGY-BALANCE; CHROMOSPHERE; CORONA; SPECTROMETER AB Measurements of umbral-to-quiet Sun and umbral-to-plage contrast in five active regions have been obtained in the transition region emission lines Si IV lambda1402.77, C IV lambda1548.19, and 0 V 1371.29 using the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission. The umbral transition region in these lines appears generally indistinguishable from the quiet transition region. In addition, high-resolution profiles of the C IV lines lambdalambda1548.19, 1550.77 in the umbrae of eight individual sunspots in different active regions show only weak, mostly subsonic, redshifted components. This result differs sharply from the observations of multiple, strong, often supersonic downflows observed with the HRTS instrument (e.g., Brekke et al.). RP GURMAN, JB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 21 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1993 VL 412 IS 2 BP 865 EP 869 DI 10.1086/172968 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN831 UT WOS:A1993LN83100035 ER PT J AU COFER, WR LEVINE, JS WINSTEAD, EL STOCKS, BJ CAHOON, DR PINTO, JP AF COFER, WR LEVINE, JS WINSTEAD, EL STOCKS, BJ CAHOON, DR PINTO, JP TI TRACE GAS EMISSIONS FROM TROPICAL BIOMASS FIRES - YUCATAN PENINSULA, MEXICO SO ATMOSPHERIC ENVIRONMENT PART A-GENERAL TOPICS LA English DT Article DE BIOMASS BURNING; EMISSION FROM BURNING; TROPICAL BURNING EMISSIONS; TRACE GAS EMISSIONS FROM BIOMASS FIRES; CARBON EMISSIONS FROM TROPICAL BURNING; EMISSION RATIOS ID BOREAL FOREST FIRES; NITROUS-OXIDE; OZONE; HYDROCARBON; AEROSOL; METHANE; CYCLES; CARBON; TRENDS AB Mixing ratios for carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H-2), methane (CH4) and total non-methane hydrocarbons (TNMHC) were determined from the smoke plumes of two small (approximately 0.25 ha) prescribed biomass fires conducted on the Yucatan Peninsula in Mexico. In the region of these fires the combination of climate and shallow soils produces a scrubby and stunted forest with species composition similar to the Brazilian rain forest, but at a noticeably reduced size. Aircraft collections of smoke from these fires were analysed and used to determine CO2-normalized emission ratios (DELTAX/DELTACO2; v/v; where DELTA = in-plume specie concentration less background concentration) for CO, H-2, CH4 and TNMHC produced and released into the atmosphere from these fires. Surprisingly, high mean emission ratios for TNMHCs (approximately 1.7% of CO2 release) and H-2 (approximately 2.5% of CO2) were determined. Emission ratios for CO (approximately 7%) and CH4 (approximately 0.7%), however, were found to fall within expected bounds. C1 HUGHES STX CORP,HAMPTON,VA 23666. US EPA,ATMOSPHER RES & EXPOSURE ASSESSMENT LAB,RES TRIANGLE PK,NC 27711. GREAT LAKES FORESTRY CTR,SAULT ST MARIE P6A 5M7,ONTARIO,CANADA. RP COFER, WR (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. NR 33 TC 7 Z9 7 U1 0 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0004-6981 J9 ATMOS ENVIRON A-GEN PD AUG PY 1993 VL 27 IS 12 BP 1903 EP 1907 DI 10.1016/0960-1686(93)90295-A PG 5 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA LX597 UT WOS:A1993LX59700012 ER PT J AU HERRINGTON, DM SIEBES, M WALFORD, GD AF HERRINGTON, DM SIEBES, M WALFORD, GD TI SOURCES OF ERROR IN QUANTITATIVE CORONARY ANGIOGRAPHY SO CATHETERIZATION AND CARDIOVASCULAR DIAGNOSIS LA English DT Article DE QUANTITATIVE CORONARY ANGIOGRAPHY; CORONARY PHANTOMS; EDGE DETECTION ID CINEANGIOGRAMS; STENOSIS; GLARE AB Many studies have reported the accuracy of quantitative coronary angiography (QCA) based on experiments using moderated-size phantoms imaged under unrealistic radiographic conditions. However, these observations may not be-generalizable to the setting of clinical angiography. To determine QCA accuracy in a realistic radiographic setting and evaluate the impact of the x-ray system line spread function, plexiglass phantoms were imaged inside and out of a human thorax. A realistic radiographic background was associated with a 38% increase in variability of results (P < 0.05). Low concentrations of contrast and large image intensifier input screens were associated with significantly larger errors and variability in results (p < 0.05). There was a systematic overestimation of diameter in the smallest phantom. A mathematical model of the x-ray line spread function was developed that explains the observed overestimation of the smallest phantom and provide a rational approach for correction of the line spread function for QCA. Many factors encountered in clinical coronary angiography such as nonuniform radiographic background, low concentrations of contrast, and small vessel diameters have a significant adverse impact on the accuracy and/or variability of gradient-based edge detection QCA systems. (C) 1993 Wiley-Liss, Inc. C1 JOHNS HOPKINS UNIV,DEPT MED,DIV CARDIOL,BALTIMORE,MD 21218. JET PROP LAB,PASADENA,CA 91109. RP HERRINGTON, DM (reprint author), BOWMAN GRAY SCH MED,DIV CARDIOL,MED CTR BLVD,WINSTON SALEM,NC 27157, USA. RI Siebes, Maria/A-9870-2008 OI Siebes, Maria/0000-0002-7034-5843 FU NHLBI NIH HHS [HL-23619, HL07642] NR 22 TC 18 Z9 18 U1 0 U2 0 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0098-6569 J9 CATHETER CARDIO DIAG JI Catheter. Cardiovasc. Diagn. PD AUG PY 1993 VL 29 IS 4 BP 314 EP 321 DI 10.1002/ccd.1810290416 PG 8 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA LQ044 UT WOS:A1993LQ04400015 PM 8221856 ER PT J AU DOWKER, HF AF DOWKER, HF TI SO(4)-INVARIANT STATES IN QUANTUM COSMOLOGY SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article ID DESITTER SPACETIME; LINEARIZATION INSTABILITIES; EINSTEIN EQUATIONS; UNIVERSE AB The phenomenon of linearization instability is identified in models of quantum cosmology that are perturbations of mini-superspace models. In particular, constraints that are second-order in the perturbations must be imposed on wavefunctions calculated in such models. It is shown explicitly that in the case of a model which is a perturbation of the mini-superspace which has S3 spatial sections these constraints imply that any wavefunctions calculated in this model must be SO(4)-invariant. RP DOWKER, HF (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,POB 500,BATAVIA,IL 60510, USA. NR 19 TC 0 Z9 0 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD AUG PY 1993 VL 10 IS 8 BP 1435 EP 1446 DI 10.1088/0264-9381/10/8/006 PG 12 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LV474 UT WOS:A1993LV47400006 ER PT J AU BUCY, RS WILLIAMS, BG AF BUCY, RS WILLIAMS, BG TI A MATRIX CROSS RATIO THEOREM FOR THE RICCATI EQUATION SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article DE RICCATI EQUATION; CROSS RATIO; SINGULAR FILTERING; SINGULAR PERTURBATION EXPANSION; TRANSIENT SOLUTIONS AB The notion of the cross ratio and its invariance under bilinear mappings is an important result of classical complex analysis. The cross ratio has been extended to functions of several complex variables by C. L. Siegel in his study of the symplectic group. We present in this paper a new result for a generalized cross ratio valid for solutions to the matrix Riccati equation. An application of this generalized cross ratio to singular filtering problems allows one to develop a singular perturbation expansion with matrix coefficients for the solution to the corresponding Riccati equation. C1 JET PROP LAB,PASADENA,CA 91109. RP BUCY, RS (reprint author), UNIV SO CALIF,DEPT AEROSP ENGN,LOS ANGELES,CA 90089, USA. NR 23 TC 2 Z9 2 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0898-1221 J9 COMPUT MATH APPL JI Comput. Math. Appl. PD AUG PY 1993 VL 26 IS 4 BP 9 EP 20 DI 10.1016/0898-1221(93)90030-Y PG 12 WC Mathematics, Applied SC Mathematics GA LK626 UT WOS:A1993LK62600002 ER PT J AU PREMACK, T DOUGLAS, AS AF PREMACK, T DOUGLAS, AS TI AN ANALYSIS OF THE CRACK-TIP FIELDS IN A DUCTILE 3-POINT BEND SPECIMEN SUBJECTED TO IMPACT LOADING SO ENGINEERING FRACTURE MECHANICS LA English DT Article ID FINITE-ELEMENT ANALYSIS; FRACTURE INITIATION; DYNAMIC FRACTURE; CLOSURE AB Analyses of an impact fracture test of a precracked, three-point beam of HY100 steel were performed to determine the dynamic fracture toughness. During impact, the crack tip opening displacement (CTOD) 100 mum behind the crack tip was measured using an optical measuring device called the interferometric strain/displacement gage. Since fracture initiates when stress wave effects dominate, a numerical simulation of the fracture event was conducted to obtain relevant near crack tip field parameters. The specimen was modeled by a plane stress finite element simulation using a rate sensitive elastoplastic material law. Since the simulated CTOD was to be compared with the measured CTOD in a region of residual strains due to crack closure, this effect was included in the model. The simulation produces a CTOD versus time response within 10% of the observed response, indicating that the other field quantities (such as the J-integral) should also be reliable. The loading rate K1 was approximately 8 x 10(6) MPa square-root m/sec. If the fracture initiation time is assumed to coincide with the time at which the simulated and observed CTOD curves diverge, then the impact fracture toughness is 56% higher than the static fracture toughness. C1 JOHNS HOPKINS UNIV, DEPT MECH ENGN, BALTIMORE, MD 21218 USA. RP PREMACK, T (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 751, GREENBELT, MD 20771 USA. RI Douglas, Andrew/C-6862-2009 NR 35 TC 2 Z9 2 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0013-7944 J9 ENG FRACT MECH JI Eng. Fract. Mech. PD AUG PY 1993 VL 45 IS 6 BP 717 EP 728 DI 10.1016/0013-7944(93)90060-6 PG 12 WC Mechanics SC Mechanics GA LT544 UT WOS:A1993LT54400001 ER PT J AU BEAL, KL AF BEAL, KL TI MENTORING SO FISHERIES LA English DT Article RP BEAL, KL (reprint author), NATL MARINE FISHERIES SERV,1 BLACKBURN DR,GLOUCESTER,MA 01930, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 SN 0363-2415 J9 FISHERIES JI Fisheries PD AUG PY 1993 VL 18 IS 8 BP 42 EP & PG 0 WC Fisheries SC Fisheries GA LQ637 UT WOS:A1993LQ63700014 ER PT J AU KLAIDMAN, LK ADAMS, JD LEUNG, AC KIM, SS CADENAS, E AF KLAIDMAN, LK ADAMS, JD LEUNG, AC KIM, SS CADENAS, E TI REDOX CYCLING OF MPP+ - EVIDENCE FOR A NEW MECHANISM INVOLVING HYDRIDE TRANSFER WITH XANTHINE-OXIDASE, ALDEHYDE DEHYDROGENASE, AND LIPOAMIDE DEHYDROGENASE SO FREE RADICAL BIOLOGY AND MEDICINE LA English DT Article DE MPTP; HYDRIDE TRANSFER; OXIDATIVE STRESS; FREE RADICALS ID 1-METHYL-4-PHENYLPYRIDINIUM ION MPP+; HYDROXYL RADICALS; 1-METHYL-4-PHENYL-1,2,3,6-TETRAHYDROPYRIDINE MPTP; SUPEROXIDE FORMATION; PARKINSONS-DISEASE; NADH DEHYDROGENASE; OXIDATION; HEART; INHIBITION; REDUCTASE AB MPP+ is redox active in the presence of cytochrome P450 reductase and induces the formation of O2.- and HO.. In this study, we report the redox cycling capability of MPP+ with additional enzymes and with UV photolysis detected through ESR techniques. The treatment of MPP+ with UV light resulted in the production of HO' trapped as a spin adduct. Two of the enzymes examined in this study, xanthine oxidase and aldehyde dehydrogenase, produced 02'- in the presence of substrate. However, when MPP+ was added to the incubations, the radical trapped by DMPO was HO'. This indicates that MPP+ redox cycles in the presence of these two enzymes or UV light, which produces HO.. Our data also suggest that MPP+ is reduced by lipoamide dehydrogenase. MPP+ stimulated the oxidation of reduced nicotinamide adenine dinucleotide (NADH) by the enzyme at concentrations between 2 mM and 8 mM of MPP+. Higher concentrations of MPP+ inhibited lipoamide dehydrogenase. MPP+ appears to be redox active with a number of redox enzymes. The mechanism involved may be hydride transfer from the enzymes to MPP+, rather than a direct single-electron reduction. C1 UNIV SO CALIF,SCH PHARM,DEPT MOLEC PHARMACOL & TOXICOL,LOS ANGELES,CA 90033. UNIV SO CALIF,SCH PHARM,INST TOXICOL,LOS ANGELES,CA 90033. JET PROP LAB,SPACE ENVIRONM EFFECTS GRP,PASADENA,CA 91109. FU NINDS NIH HHS [NS23515] NR 54 TC 47 Z9 47 U1 2 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0891-5849 J9 FREE RADICAL BIO MED JI Free Radic. Biol. Med. PD AUG PY 1993 VL 15 IS 2 BP 169 EP 179 DI 10.1016/0891-5849(93)90056-Z PG 11 WC Biochemistry & Molecular Biology; Endocrinology & Metabolism SC Biochemistry & Molecular Biology; Endocrinology & Metabolism GA LP109 UT WOS:A1993LP10900007 PM 8397142 ER PT J AU JONES, JH DRAKE, MJ AF JONES, JH DRAKE, MJ TI RUBIDIUM AND CESIUM IN THE EARTH AND THE MOON SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID MANTLE; ORIGIN; CONSTRAINTS; EVOLUTION; GEOCHEMISTRY; IMPACT; BA; RB; CS AB The volatility of the alkali elements makes them potential tracers of high-temperature geochemical processes. Specifically, the abundances of Rb and Cs in the silicate portions of the Earth and the Moon may be used to evaluate theories of lunar origin which involve energetic events and, hence, high temperatures. In particular, theories which involve derivation of the Moon substantially from the Earth's mantle immediately following terrestrial core formation predict that the Moon would have a higher Rb/Cs ratio than the silicate portion of the Earth. Determining Rb/Cs ratios existing 4.5 Ga ago is complicated by differentiation and alteration processes. In general, ancient terrestrial ''basaltic'' rocks have lower Rb/Cs ratios than modern MORB and OIB. This apparent secular change is plausibly attributed to low-grade metamorphism and exchange of Rb and Cs with the surrounding crust. An acceptable mass balance for the alkalis appears to be provided by the continental crust (Rb/Cs approximately 25), MORB mantle (Rb/Cs approximately 80), and OIB mantle (Rb/Cs approximately 80). Presently, these are the only major reservoirs of Rb and Cs that have been well characterized. Since only 50% of the Rb resides in the continental crust, the silicate portion of the Earth must have a Rb/Cs ratio between 25 and 80. We conclude that the bulk Earth has a Rb/Cs ratio 1.5X that of the continental crust, approximately 40. Lunar mare basalts have Rb/Cs ratios of about 20, whereas lunar terrae rocks have lower Rb/Cs ratios. The Moon appears to have a Rb/Cs ratio between 15 and 20. The Rb/Cs ratio of the Moon is lower than the silicate portion of the Earth, contrary to the prediction of theories which derive the Moon entirely from the Earth. For the giant impact hypothesis to be correct, there have been alkali element contributions to the Moon from other sources (e.g., the impactor). Depending on the Earth's contribution to the mass of the Moon, these additional sources of alkalis must have had a combined Rb/Cs ratio comparable to or lower than that of the Moon. C1 UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. RP NASA, LYNDON B JOHNSON SPACE CTR, MAIL CODE SN4, HOUSTON, TX 77058 USA. NR 32 TC 13 Z9 13 U1 2 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 EI 1872-9533 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD AUG PY 1993 VL 57 IS 15 BP 3785 EP 3792 DI 10.1016/0016-7037(93)90155-P PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LT279 UT WOS:A1993LT27900021 ER PT J AU CANFIELD, DE MARAIS, DJD AF CANFIELD, DE MARAIS, DJD TI BIOGEOCHEMICAL CYCLES OF CARBON, SULFUR, AND FREE OXYGEN IN A MICROBIAL MAT SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID SULFATE REDUCTION; CYANOBACTERIAL MATS; MARINE-SEDIMENTS; ORGANIC-MATTER; PHOTOSYNTHESIS; MICROELECTRODE; SULFIDE; CARBOXYLASE; RESPIRATION; EXCRETION AB Complete budgets for carbon and oxygen have been constructed for cyanobacterial mats dominated by Microcoleus chthonoplastes from the evaporating ponds of a salt works located in Guerrero Negro, Baja California Sur, Mexico. Included in the budget are measured rates of O2 production, sulfate reduction, and elemental exchange across the mat/brine interface, day and night, at various temperatures and times of the year. We infer from this data the various sinks for O2, as well as the sources of carbon for primary production. To summarize, although seasonal variability exists, a major percentage of the O2 produced during the day did not diffuse out of the mat but was used within the mat to oxidize both organic carbon and the sulfide produced by sulfate reduction. At night, most of the O2 that diffused into the mat was used to oxidize sulfide, with O2 respiration of minor importance. During the day, the internal mat processes of sulfate reduction and O2 respiration generated as much or more inorganic carbon (DIC) for primary production as diffusion into the mat. Also, oxygenic photosynthesis was the most important process of carbon fixation, although anoxygenic photosynthesis may have been important at low light levels during some times of the year. At night, the DIC lost from the mat was mostly from sulfate reduction. Elemental fluxes across the mat/brine interface indicated that carbon with an oxidation state of greater than zero was taken up by the mat during the day and liberated from the mat at night. Overall, carbon with an average oxidation state of near zero accumulated in the mat. Both carbon fixation and carbon oxidation rates varied with temperature by a similar amount. These mats are thus closely coupled systems where rapid rates of photosynthesis both require and fuel rapid rates of heterotrophic carbon oxidation. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Canfield, Don/C-1735-2012 OI Canfield, Don/0000-0001-7602-8366 NR 43 TC 175 Z9 179 U1 2 U2 40 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD AUG PY 1993 VL 57 IS 16 BP 3971 EP 3984 DI 10.1016/0016-7037(93)90347-Y PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LW389 UT WOS:A1993LW38900012 PM 11537735 ER PT J AU BINDSCHADLER, R AF BINDSCHADLER, R TI NEW VIEWS FOR ANTARCTIC GLACIOLOGY SO GEOTIMES LA English DT Article RP BINDSCHADLER, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOLOGICAL INST PI ALEXANDRIA PA 4220 KING ST, ALEXANDRIA, VA 22302-1507 SN 0016-8556 J9 GEOTIMES JI Geotimes PD AUG PY 1993 VL 38 IS 8 BP 16 EP 19 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LQ875 UT WOS:A1993LQ87500015 ER PT J AU MARCIALIS, RL BURATTI, BJ AF MARCIALIS, RL BURATTI, BJ TI CCD PHOTOMETRY OF 2060 CHIRON IN 1985 AND 1991 SO ICARUS LA English DT Article ID 2060-CHIRON; STARS; ORBIT; COMA C1 JET PROP LAB,PASADENA,CA 91109. PALOMAR OBSERV,PASADENA,CA 91109. NR 33 TC 35 Z9 35 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1993 VL 104 IS 2 BP 234 EP 243 DI 10.1006/icar.1993.1098 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LY532 UT WOS:A1993LY53200007 ER PT J AU ALLEN, CC MORRIS, RV LAUER, HV MCKAY, DS AF ALLEN, CC MORRIS, RV LAUER, HV MCKAY, DS TI MICROSCOPIC IRON METAL ON GLASS AND MINERALS - A TOOL FOR STUDYING REGOLITH MATURITY SO ICARUS LA English DT Article C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP ALLEN, CC (reprint author), LOCKHEED ENGN & SCI CO,2400 NASA RD 1,HOUSTON,TX 77058, USA. NR 17 TC 36 Z9 37 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1993 VL 104 IS 2 BP 291 EP 300 DI 10.1006/icar.1993.1102 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LY532 UT WOS:A1993LY53200011 ER PT J AU NOLL, KS HAMMEL, HB YOUNG, L JOINER, J HACKWELL, J LYNCH, DK RUSSELL, R AF NOLL, KS HAMMEL, HB YOUNG, L JOINER, J HACKWELL, J LYNCH, DK RUSSELL, R TI 3-MU-M TO 13-MU-M SPECTRA OF IO SO ICARUS LA English DT Note C1 MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. AEROSP CORP,CTR SPACE & ENVIRONM TECHNOL,LOS ANGELES,CA 90009. RP NOLL, KS (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. RI Noll, Keith/C-8447-2012; Joiner, Joanna/D-6264-2012 NR 15 TC 2 Z9 2 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1993 VL 104 IS 2 BP 337 EP 340 DI 10.1006/icar.1993.1105 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LY532 UT WOS:A1993LY53200014 ER PT J AU UNAL, R STANLEY, DO JOYNER, CR AF UNAL, R STANLEY, DO JOYNER, CR TI PROPULSION SYSTEM-DESIGN OPTIMIZATION USING THE TAGUCHI METHOD SO IEEE TRANSACTIONS ON ENGINEERING MANAGEMENT LA English DT Note DE TAGUCHI METHOD; PARAMETER DESIGN; DESIGN FOR QUALITY; CONCEPTUAL SPACE TRANSPORTATION VEHICLE DESIGN; AND PROPULSION SYSTEM OPTIMIZATION AB This paper discusses the Taguchi method as an approach to design optimization for quality. The method is briefly explained and its application is illustrated by the use of a propulsion system design optimization study for an advanced space transportation vehicle as an example. The results suggest that the Taguchi method is a systematic and efficient approach that can aid in designing for performance, quality, and cost. Principal benefits include significant time and resource savings and the determination of parametric sensitivities and interactions. C1 PRATT & WHITNEY AIRCRAFT,W PALM BEACH,FL 33410. NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665. RP UNAL, R (reprint author), OLD DOMINION UNIV,COLL ENGN & TECHNOL,NORFOLK,VA 23529, USA. NR 24 TC 20 Z9 20 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9391 J9 IEEE T ENG MANAGE JI IEEE Trans. Eng. Manage. PD AUG PY 1993 VL 40 IS 3 BP 315 EP 322 DI 10.1109/17.233194 PG 8 WC Business; Engineering, Industrial; Management SC Business & Economics; Engineering GA LX488 UT WOS:A1993LX48800011 ER PT J AU MCMURRAY, RE HUBBARD, GS WERCINSKI, PF KELLER, RG AF MCMURRAY, RE HUBBARD, GS WERCINSKI, PF KELLER, RG TI MEV GAMMA-RAY DETECTION ALGORITHMS FOR STACKED SILICON DETECTORS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1992 IEEE NUCLEAR SCIENCE SYMP / MEDICAL IMAGING CONF ( NSS/MIC ) CY OCT 25-31, 1992 CL ORLANDO, FL SP IEEE AB By making use of the signature of a gamma ray event as it appears in N = 5 to 20 lithium-drifted silicon detectors and applying smart selection algorithm gamma rays in the range of 1 to 8MeV can be detected with good efficiency and selectivity. Examples of the types of algorithms used for different energy regions include the simple sum mode, the sum-coincidence mode used in segmented detectors, unique variations on sum-coincidence for an N-dimensional vector event, and a new and extremely useful mode for double escape peak spectroscopy at pair-production energies. The latter algorithm yields a spectrum similar to that of the pair spectrometer but without the need of the dual external segments for double escape coincidence, and without the large loss in efficiency of double escape events. Background events due to Compton scattering are largely suppressed. Monte Carlo calculations were used to model the gamma ray interactions in the silicon, in order to enable testing of a wide array of different algorithms on the event N-vectors for a large-N stack. RP MCMURRAY, RE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 8 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 1993 VL 40 IS 4 BP 882 EP 889 DI 10.1109/23.256678 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA LV991 UT WOS:A1993LV99100107 ER PT J AU JAIN, A RODRIGUEZ, G AF JAIN, A RODRIGUEZ, G TI AN ANALYSIS OF THE KINEMATICS AND DYNAMICS OF UNDERACTUATED MANIPULATORS SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB The dynamics and kinematics of manipulators that have fewer actuators than degrees of freedom are studied. These underactuated manipulators arise in a number of important applications such as free-flying space robots, hyperredundant manipulators, manipulators with structural flexibility, etc. In the analysis such underactuated manipulators are decomposed into component active and passive arms. This decomposition allows techniques previously developed for regular (fully actuated) manipulators to be applied to underactuated systems. Spatial operator identities are used to develop closed-form expressions for the generalized accelerations for the system. These expressions form the basis for a recursive O(N) dynamics algorithm. The structure of this algorithm is a hybrid of known forward and inverse dynamics algorithms for regular manipulators. Expressions and computational algorithms are also developed for the generalized and disturbance Jacobians for underactuated manipulators. The application of the results in the paper to space manipulators is also described. RP JAIN, A (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 54 Z9 63 U1 1 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD AUG PY 1993 VL 9 IS 4 BP 411 EP 422 DI 10.1109/70.246052 PG 12 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA MK082 UT WOS:A1993MK08200005 ER PT J AU PAL, SK AF PAL, SK TI UNCERTAINTY MANAGEMENT IN-SPACE STATION AUTONOMOUS RESEARCH - PATTERN-RECOGNITION PERSPECTIVE SO INFORMATION SCIENCES LA English DT Article ID FUZZY-SETS; IMAGE-ENHANCEMENT; NEURAL NETWORK; EDGE-DETECTION; ROUGH SETS; X-RAYS; ALGORITHM; ENTROPY; SELECTION; EXTRACTION AB Various space station autonomous operations where research is being conducted to support unmanned missions are discussed. The problem of representation and management of uncertainties involved in image analysis and recognition tasks of those operations is particularly addressed. Various tools based on fuzzy set theory and probability theory that reflect different kinds of ambiguity, uncertainty, and information in an image are listed. Their usefulness in providing soft decision and quantitative indices for autonomous operations is described along with the uncertainty in membership function evaluation. The merits of incorporating fuzzy set theory in neural networks and in genetic algorithms for efficient handling of uncertainties are also addressed. RP NASA, LYNDON B JOHNSON SPACE CTR, SOFTWARE TECHNOL BRANCH PT4, HOUSTON, TX 77058 USA. NR 110 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0020-0255 EI 1872-6291 J9 INFORM SCIENCES JI Inf. Sci. PD AUG 1 PY 1993 VL 72 IS 1-2 BP 1 EP 63 DI 10.1016/0020-0255(93)90028-K PG 63 WC Computer Science, Information Systems SC Computer Science GA LQ883 UT WOS:A1993LQ88300001 ER PT J AU SHARMA, SP AF SHARMA, SP TI ASSESSMENT OF NONEQUILIBRIUM RADIATION COMPUTATION METHODS FOR HYPERSONIC FLOWS SO INTERNATIONAL JOURNAL OF MODERN PHYSICS C-PHYSICS AND COMPUTERS LA English DT Review ID ELECTRON-IMPACT EXCITATION; INTEGRAL CROSS-SECTIONS; EARTHS ATMOSPHERE; DISSOCIATION; SYSTEMS AB The present understanding of shock-layer radiation in the low density regime, as appropriate to hypersonic vehicles, is surveyed. Based on the relative importance of electron excitation and radiation transport, the hypersonic flows are divided into three groups: weakly ionized, moderately ionized, and highly ionized flows. In the light of this division, the existing laboratory and flight data are scrutinized. Finally an assessment of the nonequilibrium radiation computation methods for the three regimes in hypersonic flows is presented. The assessment is conducted by comparing experimental data against the values predicted by the physical model. RP SHARMA, SP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 97 TC 1 Z9 1 U1 1 U2 1 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 9128, SINGAPORE SN 0129-1831 J9 INT J MOD PHYS C JI Int. J. Mod. Phys. C-Phys. Comput. PD AUG PY 1993 VL 4 IS 4 BP 847 EP 881 DI 10.1142/S0129183193000689 PG 35 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA LU432 UT WOS:A1993LU43200008 ER PT J AU BLIVEN, LF BRANGER, H SOBIESKI, P GIOVANANGELI, JP AF BLIVEN, LF BRANGER, H SOBIESKI, P GIOVANANGELI, JP TI AN ANALYSIS OF SCATTEROMETER RETURNS FROM A WATER-SURFACE AGITATED BY ARTIFICIAL RAIN - EVIDENCE THAT RING-WAVES ARE THE MAIN FEATURE SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID WIND-SPEED; RADAR BACKSCATTER; SEA-SURFACE; TANK; DEPENDENCE; SCATTERING; STRESS; OCEAN AB Both wind and rain roughen the sea surface, but whereas wind generates waves, rain generates craters, stalks and ring-waves. Average backscattered power for scatterometer returns from water surfaces is closely related to small scale features on the water surface, so we use backscattered power from short wind-waves as a basis to evaluate the importance of ring-waves. Experiments were conducted with a 13.5 GHz scatterometer (30-degrees incidence angle, vertical polarization) in a wind-wave tank that is enhanced by a rain simulator. Rain intensities ranged from 3-30 mm h-1 and wind friction velocities were between 10 and 50 cm s-1. The variance of sur-face elevation for small scale features xi(sm)2, i.e., ring-waves and short wind-waves, was computed for each case using data from a capacitance probe. Comparison of the data sets shows that the range of xi(sm)2 for the rain cases is comparable to that from light to moderate wind cases-so ring-wave amplitudes are not negligible. Analysis of the radar data provides evidence that ring-waves are the dominant feature contributing to the backscattered power. Thus ring-waves need to be included in scatterometer numerical models that contain rain effects. C1 INST MECAN STAT TURBULENCE,F-13003 MARSEILLE,FRANCE. UNIV CATHOLIQUE LOUVAIN,DEPT ELECT,B-1348 LOUVAIN,BELGIUM. RP BLIVEN, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 972,WALLOPS ISL,VA 23337, USA. RI bliven, francis/E-1450-2012; Branger, Hubert/E-1879-2016 OI Branger, Hubert/0000-0002-9888-681X NR 42 TC 39 Z9 39 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD AUG PY 1993 VL 14 IS 12 BP 2315 EP 2329 PG 15 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA MA760 UT WOS:A1993MA76000007 ER PT J AU VOLPE, R KHOSLA, P AF VOLPE, R KHOSLA, P TI A THEORETICAL AND EXPERIMENTAL INVESTIGATION OF IMPACT CONTROL FOR MANIPULATORS SO INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH LA English DT Article ID ROBUST AB This article describes a simple control strategy for stable hard-on-hard contact of a manipulator with the environment. The strategy is motivated by recognition of the equivalence of proportional gain explicit force control and impedance control. It is shown that negative proportional force gains, or impedance mass ratios less than unity, can equivalently provide excellent impact response without bouncing. This result is indicated by an analysis performed with an experimentally determined arm/sensor/environment model. The results are corroborated by experimental data from implementation of the control algorithms on the CMU DD Arm II system. The results confirm that manipulator impact against a stiff environment without bouncing can be readily handled by this novel control strategy. C1 CARNEGIE MELLON UNIV,INST ROBOT,DEPT ELECT & COMP ENGN,PITTSBURGH,PA 15213. RP VOLPE, R (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 38 TC 80 Z9 82 U1 0 U2 8 PU MIT PRESS PI CAMBRIDGE PA 55 HAYWARD ST JOURNALS DEPT, CAMBRIDGE, MA 02142 SN 0278-3649 J9 INT J ROBOT RES JI Int. J. Robot. Res. PD AUG PY 1993 VL 12 IS 4 BP 351 EP 365 DI 10.1177/027836499301200403 PG 15 WC Robotics SC Robotics GA LP754 UT WOS:A1993LP75400003 ER PT J AU MEYER, P ITTEN, KI KELLENBERGER, T SANDMEIER, S SANDMEIER, R AF MEYER, P ITTEN, KI KELLENBERGER, T SANDMEIER, S SANDMEIER, R TI RADIOMETRIC CORRECTIONS OF TOPOGRAPHICALLY INDUCED EFFECTS ON LANDSAT TM DATA IN AN ALPINE ENVIRONMENT SO ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING LA English DT Article AB Four radiometric correction methods for the reduction of slope-aspect effects in a Landsat TM data set are tested in a mountainous test site with regard to their physical soundness and their influence on forest classification, as well as on the visual appearance of the scene. Excellent ground reference information and a fine-resolution DEM allowed precise assessment of the applicability of the methods under investigation. The results of the study presented here demonstrate the weakness of the classical cosine correction method for radiometric correction in rugged terrain. The statistical, Minnaert and C-correction approaches, however, yielded an improvement of the forest classification and an impressive reduction of the visual topography effect. RP MEYER, P (reprint author), JET PROP LAB,MS 169-315,4800 OAK GROOVE DR,PASADENA,CA 91109, USA. NR 0 TC 172 Z9 190 U1 4 U2 24 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0924-2716 J9 ISPRS J PHOTOGRAMM JI ISPRS-J. Photogramm. Remote Sens. PD AUG PY 1993 VL 48 IS 4 BP 17 EP 28 DI 10.1016/0924-2716(93)90028-L PG 12 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA LU282 UT WOS:A1993LU28200003 ER PT J AU BLANQUET, E GOKOGLU, SA AF BLANQUET, E GOKOGLU, SA TI TRACTABLE CHEMICAL-MODELS FOR CVD OF SILICON AND CARBON SO JOURNAL DE PHYSIQUE IV LA English DT Article; Proceedings Paper CT 9TH EUROPEAN CONF ON CHEMICAL VAPOUR DEPOSITION ( EURO CVD 9 ) CY AUG 22-27, 1993 CL TAMPERE, FINLAND SP AMER SOC MET INT, CITY TAMPERE, INT SCI FDN, TAMPERE UNIV TECHNOL ID METHANE PYROLYSIS; VAPOR-DEPOSITION; KINETICS AB Tractable chemical models are validated for the CVD of silicon and carbon . Dilute silane (SiH4) and methane (CH4) in hydrogen are chosen as gaseous precursors. The chemical mechanism for each systems Si and C is deliberately reduced to three reactions in the models: one in the gas phase and two at the surface. The axial-flow CVD reactor utilized in this study has well-characterized flow and thermal fields and provides variable deposition rates in the axial direction. Comparisons between the experimental and calculated deposition rates are made at different pressures and temperatures. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 14 TC 4 Z9 4 U1 0 U2 0 PU EDITIONS PHYSIQUE PI LES ULIS CEDEX PA Z I DE COURTABOEUF AVE 7 AV DU HOGGAR, BP 112, 91944 LES ULIS CEDEX, FRANCE SN 1155-4339 J9 J PHYS IV JI J. Phys. IV PD AUG PY 1993 VL 3 IS C3 BP 43 EP 49 DI 10.1051/jp4:1993305 PG 7 WC Physics, Multidisciplinary SC Physics GA MC319 UT WOS:A1993MC31900006 ER PT J AU MINTZ, Y WALKER, GK AF MINTZ, Y WALKER, GK TI GLOBAL FIELDS OF SOIL-MOISTURE AND LAND-SURFACE EVAPOTRANSPIRATION DERIVED FROM OBSERVED PRECIPITATION AND SURFACE AIR-TEMPERATURE SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID DROUGHT SEVERITY INDEX; EVAPORATION AB The global fields of normal monthly soil moisture and land surface evapotranspiration are derived with a simple water budget model that has precipitation and potential evapotranspiration as inputs. The precipitation is observed and the potential evapotranspiration is derived from the observed surface air temperature with the empirical regression equation of Thornthwaite. It is shown that at locations where the net surface radiation flux has been measured, the potential evapotranspiration given by the Thornthwaite equation is in good agreement with those obtained with the radiation-based formulations of Priestley and Taylor, Penman, and Budyko, and this provides the justification for the use of the Thornthwaite equation. After deriving the global fields of soil moisture and evapotranspiration, the assumption is made that the potential evapotranspiration given by the Thornthwaite equation and by the Priestley-Taylor equation will everywhere be about the same; and the inverse of the Priestley-Taylor equation is used to obtain the normal monthly global fields of net surface radiation flux minus ground heat storage. This and the derived evapotranspiration are then used in the equation for energy conservation at the surface of the earth to obtain the global fields of normal monthly sensible heat flux from the land surface to the atmosphere. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771. NR 67 TC 133 Z9 138 U1 4 U2 20 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD AUG PY 1993 VL 32 IS 8 BP 1305 EP 1334 DI 10.1175/1520-0450(1993)032<1305:GFOSMA>2.0.CO;2 PG 30 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP690 UT WOS:A1993LP69000001 ER PT J AU SHORT, DA WOLFF, DB ROSENFELD, D ATLAS, D AF SHORT, DA WOLFF, DB ROSENFELD, D ATLAS, D TI A STUDY OF THE THRESHOLD METHOD UTILIZING RAIN-GAGE DATA SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID CONVECTIVE RAINFALL; AREA INTEGRALS; SATELLITE; MONSOON AB The threshold method for estimation of area-average rain rate relies on determination of the fractional area where rain rate exceeds a preset level of intensity. Previous studies have shown that the optimal threshold level depends on the climatological rain-rate distribution (RRD). It has also been noted, however, that the climatological RRD may be composed of an aggregate of distributions, one for each of several distinctly different synoptic conditions, each having its own optimal threshold. In this study, the impact of RRD variations on the threshold method is shown in an analysis of 1-min rain-rate data from a network of tipping-bucket gauges in Darwin, Australia. Data are analyzed for two distinct regimes: the premonsoon environment, having isolated intense thunderstorms, and the active monsoon rains, having organized convective cell clusters that generate large areas of stratiform rain. It is found that a threshold of 10 mm h-1 results in the same threshold coefficient for both regimes, suggesting an alternative definition of optimal threshold as that which is least sensitive to distribution variations. The observed behavior of the threshold coefficient is well simulated by assumption of lognormal distributions with different scale parameters and same shape parameters. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 910-1,GREENBELT,MD 20771. APPL RES CORP,LANDOVER,MD. HEBREW UNIV JERUSALEM,DEPT ATMOSPHER SCI,JERUSALEM,ISRAEL. RI Rosenfeld, Daniel/F-6077-2016 OI Rosenfeld, Daniel/0000-0002-0784-7656 NR 26 TC 31 Z9 31 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD AUG PY 1993 VL 32 IS 8 BP 1379 EP 1387 DI 10.1175/1520-0450(1993)032<1379:ASOTTM>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP690 UT WOS:A1993LP69000005 ER PT J AU ABEL, P GUENTHER, B GALIMORE, RN COOPER, JW AF ABEL, P GUENTHER, B GALIMORE, RN COOPER, JW TI CALIBRATION RESULTS FOR NOAA-11 AVHRR CHANNEL-1 AND CHANNEL-2 FROM CONGRUENT PATH AIRCRAFT OBSERVATIONS SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB A method for using congruent atmospheric path aircraft-satellite observations to calibrate a satellite radiometer is presented. A calibrated spectroradiometer aboard a NASA ER-2 aircraft at an altitude of 19 km above White Sands, New Mexico, was oriented to view White Sands at the overpass time of the NOAA-11 Advanced Very High Resolution Radiometer (AVHRR) instrument along the same view vector as the satellite instrument. The data from six flights between November 1988 and October 1990 were transformed into corresponding estimates of AVHRR channel radiance at the satellite (derived from the aircraft measurements), and average counts (from the AVHRR measurements), both averaged across the footprint of the spectroradiometer. Prelaunch measurements of the AVHRR spectral response profiles are assumed, and the radiance spectrum measured by the spectroradiometer was adjusted to satellite attitude using the LOWTRAN-7 computer code. Spatial misregistration of the two flight datasets was corrected by maximizing the correlation between them. Results show reduced gains in both channel 1 (0.65 mum) and channel 2 (0.85 mum), compared to prelaunch values, with little further reduction in gain after 200 days in orbit. Results for the gain ratio (channel 1/channel 2), which is important for the calculation of the normalized vegetation index, show constant in-orbit values 5% above the prelaunch value. Estimates of uncertainty in the results are presented, as well as ideas for their reduction in the analysis of future flights. RP ABEL, P (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SENSOR DEV & CHARACTERIZAT BRANCH,GREENBELT,MD 20771, USA. NR 0 TC 44 Z9 45 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD AUG PY 1993 VL 10 IS 4 BP 493 EP 508 DI 10.1175/1520-0426(1993)010<0493:CRFACA>2.0.CO;2 PG 16 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA ME698 UT WOS:A1993ME69800006 ER PT J AU HOVENAC, EA LOCK, JA AF HOVENAC, EA LOCK, JA TI CALIBRATION OF THE FORWARD-SCATTERING SPECTROMETER PROBE - MODELING SCATTERING FROM A MULTIMODE LASER-BEAM SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB Scattering calculations using a more detailed model of the multimode laser beam in the forward-scattering spectrometer probe (FSSP) were carried out by using a recently developed extension to Mie scattering theory. From this model, new calibration curves for the FSSP were calculated. The difference between the old calibration curves and the new ones is small for droplet diameters less than 10 mum, but the difference increases to approximately 10% at diameters of 50 mum. When using glass beads to calibrate the FSSP. calibration errors can be minimized, by using glass beads of many different diameters, over the entire range of the FSSP. If the FSSP is calibrated using one-diameter glass beads, then the new formalism is necessary to extrapolate the calibration over the entire range. RP HOVENAC, EA (reprint author), NASA,LEWIS RES CTR GRP MS771,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 0 TC 8 Z9 8 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD AUG PY 1993 VL 10 IS 4 BP 518 EP 525 DI 10.1175/1520-0426(1993)010<0518:COTFSS>2.0.CO;2 PG 8 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA ME698 UT WOS:A1993ME69800008 ER PT J AU BANERJEE, RK CHO, YI BACK, LH AF BANERJEE, RK CHO, YI BACK, LH TI NUMERICAL-STUDIES OF 3-DIMENSIONAL ARTERIAL FLOWS IN REVERSE CURVATURE GEOMETRY .1. PEAK FLOW SO JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID CURVED PIPE AB A three-dimensional flow simulation at Re(peak) = 192 and 580 was made in a smooth reverse curvature model that conformed to the gentle ''S'' shape from a human left femoral artery angiogram. The objective of this numerical investigation was to find the changes in pressure, shear stress, velocity profile, and particle path occurring in the double-curved arterial vessel. Due to the impingement of blood at the outer wall in the first bend region, the wall shear stress approached 40 dyne/cm2-a value over twice as large as in the straight upstream segment. Conversely, at the inner wall in the first bend, a low shear stress region was found where the value of the shear stress was consistently smaller than that in the straight section. The initiation of centrifugal effects caused by the first bend could clearly be seen at Re(peak) = 580, but due to the close proximity of the reverse curvature segment, the momentum effect due to the second bend overshadowed the centrifugal effect. Hence, only near the end of the second bend did the centrifugal effect due to the second bend result in a double-spiral-secondary motion. In addition, the numerically calculated pressure drop data were in agreement with prior experimental values. C1 JET PROP LAB,PASADENA,CA 91109. RP BANERJEE, RK (reprint author), DREXEL UNIV,DEPT MECH ENGN & MECH,PHILADELPHIA,PA 19104, USA. NR 24 TC 13 Z9 14 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0148-0731 J9 J BIOMECH ENG-T ASME JI J. Biomech. Eng.-Trans. ASME PD AUG PY 1993 VL 115 IS 3 BP 316 EP 326 DI 10.1115/1.2895492 PG 11 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA LU766 UT WOS:A1993LU76600016 PM 8231148 ER PT J AU ARNAUD, SB WRONSKI, TJ FUNG, P NAVIDI, M BALLARD, R AF ARNAUD, SB WRONSKI, TJ FUNG, P NAVIDI, M BALLARD, R TI CALCIUM-METABOLISM AND BONE HISTOMORPHOMETRY IN MATURE AND YOUNG RHESUS-MONKEYS DURING REDUCED ACTIVITY SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV FLORIDA,GAINESVILLE,FL 32611. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1993 VL 8 SU 1 BP S281 EP S281 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA LR205 UT WOS:A1993LR20500658 ER PT J AU BIKLE, DD HALLORAN, BP HARRIS, J MOREYHOLTON, E AF BIKLE, DD HALLORAN, BP HARRIS, J MOREYHOLTON, E TI SKELETAL UNLOADING INDUCES RESISTANCE TO IGF-1 SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 VET ADM MED CTR,ENDOCRINE RES UNIT,SAN FRANCISCO,CA 94121. UNIV CALIF SAN FRANCISCO,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 1 Z9 1 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1993 VL 8 SU 1 BP S155 EP S155 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA LR205 UT WOS:A1993LR20500154 ER PT J AU HUTCHINSON, TM MARTIN, B KIRATLI, J ZHOU, LJ ROBERTS, S STEELE, CR ARNAUD, SB AF HUTCHINSON, TM MARTIN, B KIRATLI, J ZHOU, LJ ROBERTS, S STEELE, CR ARNAUD, SB TI EVALUATION OF MECHANICAL RESPONSE TISSUE-ANALYSIS (MRTA) IN MONKEY TIBIAS - A NONINVASIVE DIRECT MEASUREMENT SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF DAVIS,SACRAMENTO MED CTR,DEPT ORTHOPED,SACRAMENTO,CA 95817. STANFORD UNIV,DIV APPL MECH,STANFORD,CA 94305. VET ADM MED CTR,PALO ALTO,CA 94305. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1993 VL 8 SU 1 BP S268 EP S268 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA LR205 UT WOS:A1993LR20500606 ER PT J AU JORGENSON, P TURKEL, E AF JORGENSON, P TURKEL, E TI CENTRAL DIFFERENCE TVD SCHEMES FOR TIME-DEPENDENT AND STEADY-STATE PROBLEMS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID SHOCK-CAPTURING SCHEMES; CONSERVATION-LAWS C1 TEL AVIV UNIV,SACKLER FAC EXACT SCI,IL-69978 TEL AVIV,ISRAEL. RP JORGENSON, P (reprint author), NASA,LEWIS RES CTR,ICOMP,CLEVELAND,OH 44135, USA. RI Turkel, Eli/F-6297-2011 OI Turkel, Eli/0000-0003-4273-0303 NR 14 TC 26 Z9 26 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1993 VL 107 IS 2 BP 297 EP 308 DI 10.1006/jcph.1993.1145 PG 12 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA LN472 UT WOS:A1993LN47200009 ER PT J AU HAAS, BL MCDONALD, JD DAGUM, L AF HAAS, BL MCDONALD, JD DAGUM, L TI MODELS OF THERMAL RELAXATION MECHANICS FOR PARTICLE SIMULATION METHODS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID TRANSLATIONAL ENERGY-TRANSFER; COLLISION C1 MASPAR COMP CORP,SUNNYVALE,CA 94086. NASA,AMES RES CTR,COMP SCI CORP,MOFFETT FIELD,CA 94035. ELORET INST,PALO ALTO,CA 94303. NR 19 TC 9 Z9 10 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1993 VL 107 IS 2 BP 348 EP 358 DI 10.1006/jcph.1993.1149 PG 11 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA LN472 UT WOS:A1993LN47200013 ER PT J AU SHA, YG SU, CH SZOFRAN, FR AF SHA, YG SU, CH SZOFRAN, FR TI THERMODYNAMIC ANALYSIS AND MASS FLUX OF THE HGZNTE-HGI2 CHEMICAL-VAPOR TRANSPORT-SYSTEM SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID HG1-XCDXTE EPITAXIAL LAYERS; LIQUID-PHASE EPITAXY; VACANCY CONCENTRATION; SOLID-SOLUTIONS; GROWTH; HG0.8CD0.2TE; DIAGRAM; ALLOYS; CVT; HG AB A comprehensive thermo-chemical analysis of the HgZnTe-HgI2 chemical vapor transport (CVT) system was performed. The equilibrium partial pressures of vapor species were calculated and the mass flux equations of the four major species solved simultaneously using numerical methods. The mass transport rates and the alloy compositions of the deposited material as a function of transport agent (HgI2) pressure and of undercooling temperature are predicted for fixed source temperature (600-degrees-C) and composition, Hg0.84Zn0.16Te. The reasonably good agreement between the experimental mass transport results and the theoretical calculations confirms the validity of the analytical model applied to the CVT process of this system. RP SHA, YG (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 55 TC 6 Z9 6 U1 1 U2 2 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 AUG PY 1993 VL 131 IS 3-4 BP 574 EP 588 DI 10.1016/0022-0248(93)90210-N PG 15 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA LU487 UT WOS:A1993LU48700034 ER PT J AU CHAN, WM SHARIFF, K PULLIAM, TH AF CHAN, WM SHARIFF, K PULLIAM, TH TI INSTABILITIES OF 2-DIMENSIONAL INVISCID COMPRESSIBLE VORTICES SO JOURNAL OF FLUID MECHANICS LA English DT Article ID ACOUSTIC INSTABILITY; RANKINE VORTEX; SHALLOW-WATER; EQUATIONS; STABILITY; MODES; FLOWS; GAS AB The linear stability and subsequent nonlinear evolution and acoustic radiation of a planar inviscid compressible vortex is examined. Linear-stability analysis shows that vortices with smoother vorticity profiles than the Rankine vortex considered by Broadbent & Moore (1979) are also unstable. However, only neutrally stable waves are found for a Gaussian vorticity profile. The effects of entropy gradient are investigated and for the particular entropy profile chosen, positive average entropy gradient in the vortex core is destabilizing while the opposite is true for negative average entropy gradient. The linear initial-value problem is studied by finite-difference methods. It is found that these methods are capable of accurately computing the frequencies and weak growth rates of the normal modes. When the initial condition consists of random perturbations, the long-time behaviour is found to correspond to the most unstable normal mode in all cases. In particular, the Gaussian vortex has no algebraically growing modes. This procedure also reveals the existence of weakly decaying and neutrally stable waves rotating in the direction opposite to the vortex core, which were not observed previously. The nonlinear development of an elliptic-mode perturbation is studied by numerical solution of the Euler equations. The vortex elongates and forms shocklets; eventually, the core splits into two corotating vortices. The individual vortices then gradually move away from each other while their rate of rotation about their mid-point slowly decreases. The acoustic flux reaches a maximum at the time of fission and decreases as the vortices move apart. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. RP CHAN, WM (reprint author), NASA,AMES RES CTR,MS T045-2,MOFFETT FIELD,CA 94035, USA. OI Shariff, Karim/0000-0002-7256-2497 NR 50 TC 17 Z9 17 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD AUG PY 1993 VL 253 BP 173 EP 209 DI 10.1017/S0022112093001764 PG 37 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA LV212 UT WOS:A1993LV21200008 ER PT J AU CHEN, YM OU, YR PEARLSTEIN, AJ AF CHEN, YM OU, YR PEARLSTEIN, AJ TI DEVELOPMENT OF THE WAKE BEHIND A CIRCULAR-CYLINDER IMPULSIVELY STARTED INTO ROTATORY AND RECTILINEAR MOTION SO JOURNAL OF FLUID MECHANICS LA English DT Article ID REYNOLDS-NUMBERS; VISCOUS-FLOW; SEPARATED FLOWS; STEADY; EQUATIONS; BODIES; STABILITY; SYSTEMS AB The temporal development of two-dimensional viscous incompressible flow generated by a circular cylinder impulsively started into steady rotatory and rectilinear motion at Re = 200 (based on the cylinder diameter 2a and the magnitude U of the rectilinear velocity) is studied computationally. We use an explicit finite-difference/pseudospectral technique and a new implementation of the Biot-Savart law to integrate a velocity/vorticity formulation of the Navier-Stokes equations. Results are presented for the four angular: rectilinear speed ratios alpha = OMEGAa/U (where OMEGA is the angular speed) considered experimentally by Coutanceau & Menard (1985). For alpha less-than-or-equal-to 1, extension of the computations to dimensionless times larger than achieved either in the experimental work or in the computations of Badr & Dennis (1985) allows for a more complete discussion of the temporal development of the wake. Using the frame-invariant vorticity distribution, we discuss several aspects of the vortex kinematics and dynamics not revealed by the earlier work, in which vortex cores were identified from frame-dependent streamline and streamfunction information. Consideration of the flow in the absence of sidewalls confirms the artifactual nature of the trajectory of the first vortex reported by Coutanceau & Menard for alpha = 3.25. For alpha greater than unity (the largest value considered by Badr & Dennis), our results indicate that at Re = 200 shedding of more than one vortex does indeed occur for alpha = 3.25 (and possibly for larger alpha), in contrast to the conclusion of Coutanceau & Menard. Moreover, the shedding process is very different from that associated with the usual Karman vortex street for alpha = 0. Specifically, consecutive vortices can be shed from one side of the cylinder and be of the same sense, in contrast to the non-rotating case, in which mirror-image vortices of opposite sense are shed alternately from opposite sides of the cylinder. The results are discussed in relation to the possibility of suppressing vortex shedding by open- or closed-loop control of the rotation rate. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. UNIV ILLINOIS,DEPT MECH & IND ENGN,URBANA,IL 61801. OI Pearlstein, Arne/0000-0002-7044-5537 NR 66 TC 51 Z9 56 U1 0 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD AUG PY 1993 VL 253 BP 449 EP 484 DI 10.1017/S0022112093001867 PG 36 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA LV212 UT WOS:A1993LV21200018 ER PT J AU SAIKI, EM BIRINGEN, S DANABASOGLU, G STREETT, CL AF SAIKI, EM BIRINGEN, S DANABASOGLU, G STREETT, CL TI SPATIAL SIMULATION OF SECONDARY INSTABILITY IN PLANE CHANNEL FLOW - COMPARISON OF K-TYPE AND H-TYPE DISTURBANCES SO JOURNAL OF FLUID MECHANICS LA English DT Article ID BOUNDED SHEAR FLOWS; NUMERICAL-SIMULATION; POISEUILLE FLOW; TRANSITION; TURBULENCE; EQUATION; LAYER AB This study involves a numerical simulation of spatially evolving secondary instability in plane channel flow. The computational algorithm integrates the time-dependent, three-dimensional, incompressible Navier-Stokes equations by a mixed finite-difference/spectral technique. In particular, we are interested in the differences between instabilities instigated by Klebanoff (K-) type and Herbert (H-) type inflow conditions, and in comparing the present spatial results with previous temporal models. It is found that for the present inflow conditions, H-type instability is biased towards one of the channel walls, while K-type instability evolves on both walls. For low initial perturbation amplitudes, H-type instability exhibits higher growth rates than K-type instability while higher initial amplitudes lead to comparable growth rates of both H- and K-type instability. In H-type instability, spectral analysis reveals the presence of the subharmonic two-dimensional mode which promotes the growth of the three-dimensional spanwise and fundamental modes through nonlinear interactions. An intermodal energy transfer study demonstrates that there is a net energy transfer from the three-dimensional modes to the two-dimensional mode. This analysis also indicates that the mean mode transfers net energy to the two-dimensional subharmonic mode and to the three-dimensional modes. C1 UNIV COLORADO,DEPT AEROSP ENGN SCI,BOULDER,CO 80309. NASA,LANGLEY RES CTR,DIV FLUID DYNAM,THEORET AERODYNAM BRANCH,HAMPTON,VA 23665. NR 44 TC 13 Z9 13 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD AUG PY 1993 VL 253 BP 485 EP 507 DI 10.1017/S0022112093001879 PG 23 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA LV212 UT WOS:A1993LV21200019 ER PT J AU CHOI, HC TEMAM, R MOIN, P KIM, J AF CHOI, HC TEMAM, R MOIN, P KIM, J TI FEEDBACK-CONTROL FOR UNSTEADY-FLOW AND ITS APPLICATION TO THE STOCHASTIC BURGERS-EQUATION SO JOURNAL OF FLUID MECHANICS LA English DT Article ID NAVIER-STOKES EQUATIONS; VISCOUS DRAG REDUCTION; TURBULENCE AB Mathematical methods of control theory are applied to the problem of control of fluid flow with the long-range objective of developing effective methods for the control of turbulent flows. The procedure of how to cast the problem of controlling turbulence into a problem in optimal control theory is presented using model problems through the formalism and language of control theory. Then we present a suboptimal control and feedback procedure for general stationary and time-dependent problems using methods of calculus of variations through the adjoint state and gradient algorithms. This suboptimal feedback control procedure is applied to the stochastic Burgers equation. Two types of controls are investigated: distributed and boundary controls. The control inputs are the momentum forcing for the distributed control and the boundary velocity for the boundary control. Costs to be minimized are defined as the sum of the mean-square velocity gradient inside the domain for the distributed control or the square velocity gradient at the wall for the boundary control; and in both cases a term was added to account for the implementation cost. Several cases of both controls have been numerically simulated to investigate the performances of the control algorithm. Most cases considered show significant reductions of the costs. Another version of the feedback procedure more effective for practical implementation has been considered and implemented, and the application of this algorithm also shows significant reductions of the costs. Finally, dependence of the control algorithm on the time-discretization method is discussed. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV PARIS 11,ANALYSE NUMER LAB,F-91405 ORSAY,FRANCE. RP CHOI, HC (reprint author), STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305, USA. RI Choi, Haecheon/D-1016-2011 OI Choi, Haecheon/0000-0003-0696-847X NR 30 TC 111 Z9 112 U1 0 U2 5 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD AUG PY 1993 VL 253 BP 509 EP 543 DI 10.1017/S0022112093001880 PG 35 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA LV212 UT WOS:A1993LV21200020 ER PT J AU RANGWALLA, AA RAI, MM AF RANGWALLA, AA RAI, MM TI A NUMERICAL-ANALYSIS OF TONAL ACOUSTICS IN ROTOR-STATOR INTERACTIONS SO JOURNAL OF FLUIDS AND STRUCTURES LA English DT Article ID NAVIER-STOKES SIMULATIONS; BOUNDARY-CONDITIONS; FAR FIELD; TURBINE; FLOWS; STAGE RP RANGWALLA, AA (reprint author), NASA,AMES RES CTR,INST MCAT,MOFFETT FIELD,CA 94035, USA. NR 28 TC 10 Z9 10 U1 0 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0889-9746 J9 J FLUID STRUCT JI J. Fluids Struct. PD AUG PY 1993 VL 7 IS 6 BP 611 EP 637 DI 10.1006/jfls.1993.1037 PG 27 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA LV924 UT WOS:A1993LV92400003 ER PT J AU OSHEROVICH, VA FARRUGIA, CJ BURLAGA, LF AF OSHEROVICH, VA FARRUGIA, CJ BURLAGA, LF TI NONLINEAR EVOLUTION OF MAGNETIC-FLUX ROPES .1. LOW-BETA LIMIT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SELF-SIMILAR MAGNETOHYDRODYNAMICS; VENUS IONOSPHERE; Z-PINCH; FIELDS; MAGNETOTAIL; DYNAMICS; CLOUDS; PLASMA AB An understanding of fully developed nonlinear MHD phenomena becomes increasingly essentia or the interpretation of magnetospheric and interplanetary observations. in a series of four papers we shall study the nonlinear, self-similar evolution of a cylindrical magnetic flux tube with two components of the magnetic field, axial (B(z)) and azimuthal (B(phi)). In this first paper we restrict ourselves to the case of a plasma of low beta. (Subsequent papers deal with finite beta effects, with dissipation, and with a data example.) Introducing a special class of configurations we call ''separable fields,'' we reduce the problem to an ordinary differential equation. Two cases are to be distinguished: (1) when the total field minimizes on the symmetry axis, the magnetic configuration inexorably collapses, and (2) when, on the other hand, the total field maximizes on the symmetry axis, the magnetic configuration behaves analogously to a nonlinear oscillator. Here we focus on the latter case. The effective potential of the motion contains two terms: a strong, repulsive term associated with the gradient of B(z)2/8pi and a weak, restoring term associated with the pinch. We solve the nonlinear differential equation of motion numerically and find that the period of oscillations grows exponentially with the energy of the oscillator. Our treatment emphasizes the role of the force-free configuration as the lowest potential energy state about which the system oscillates. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP OSHEROVICH, VA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 33 TC 39 Z9 42 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1993 VL 98 IS A8 BP 13225 EP 13231 DI 10.1029/93JA00271 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LR054 UT WOS:A1993LR05400004 ER PT J AU SIREGAR, E ROBERTS, DA GOLDSTEIN, ML AF SIREGAR, E ROBERTS, DA GOLDSTEIN, ML TI QUASI-PERIODIC TRANSVERSE-PLASMA FLOW ASSOCIATED WITH AN EVOLVING MHD VORTEX STREET IN THE OUTER HELIOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; MERIDIONAL TRANSPORT; MAGNETIC-FLUX AB We study a transverse (''meridional'' in heliocentric coordinates) plasma flow induced by the evolution of a Karman vortex street using a Chebyshev-Fourier spectral algorithm to solve both the compressible Navier-Stokes and magnetohydrodynamic (MHD) equations. The evolving vortex street is formed by the nonlinear interaction of two vortex sheets initially in equilibrium, such as are naturally found either side of the heliospheric current sheet at solar minimum. We study spatial profiles of the total plasma velocity, the density, the meridional flow angle and the location of sector boundaries and find generally good agreement with Voyager 2 measurements of quasi-periodic transverse flow in the outer heliosphere. The pressure pulses associated with the meridional flows in the simulation are too small, although they are correctly located, and this may be due to the lack of any ''warp'' in the current sheet in this model. A strong, flow-aligned magnetic field, such as would occur in the inner heliosphere, is shown to lead to weak effects that would be masked by the background interplanetary turbulence. We also study the plasma and magnetic transport resulting from the meridional flow, and find that deficits of magnetic quantities do occur near the ecliptic and that while the effect is relatively small, it is in general agreement with the most recent analysis of 'flux deficit' in the outer heliosphere. RP SIREGAR, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Goldstein, Melvyn/B-1724-2008 NR 17 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1993 VL 98 IS A8 BP 13233 EP 13246 DI 10.1029/93JA01032 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LR054 UT WOS:A1993LR05400005 ER PT J AU FEYNMAN, J SPITALE, G WANG, J GABRIEL, S AF FEYNMAN, J SPITALE, G WANG, J GABRIEL, S TI INTERPLANETARY PROTON FLUENCE MODEL - JPL 1991 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article AB We describe an updated predictive engineering model for the interplanetary fluence of protons with energies >1, >4, >10, >30, and >60 MeV. This has been the first opportunity to derive a model from a data set that has been collected in space over a long enough period of time to produce a valid sample of solar proton events. The model provides a quantitative basis for estimating the exposures to solar protons of spacecraft during missions of varying length and of surfaces and atmospheres of solar system objects. It is derived from the set of data collected by the IMP and OGO spacecraft between 1963 and 1991. The >10 and >30 MeV data sets cover the period from 1963 to day 126 of 1991. The >1, >4, and >60 MeV data sets were collected between 1973 and 1991. Both data sets contain several major proton events (>10-MeV fluences exceeding 3 or 4 x 10(9) protons/cm2) comparable to the 1972 event. The method of statistical analysis used in producing the model of the proton environment is the same as that used for earlier models. For the cases of the >10 and >30 MeV particles, the fluences are somewhat lower than in our earlier model (JPL 85). No >1, >4, and >60 MeV proton fluence models have been published in the literature previously. We present our results in a convenient graphical form which may be used to calculate the 1 AU fluence expected at a given confidence level as a function of the length of the exposure. A method of extending this estimate to other heliocentric distances is described. C1 UNIV SOUTHAMPTON,DEPT ASTRONAUT & AERONAUT,SOUTHAMPTON SO9 5NH,HANTS,ENGLAND. RP FEYNMAN, J (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. OI Wang, Joe/0000-0002-3298-2956 NR 10 TC 170 Z9 173 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1993 VL 98 IS A8 BP 13281 EP 13294 DI 10.1029/92JA02670 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LR054 UT WOS:A1993LR05400009 ER PT J AU CANE, HV RICHARDSON, IG VONROSENVINGE, TT AF CANE, HV RICHARDSON, IG VONROSENVINGE, TT TI COSMIC-RAY DECREASES AND PARTICLE-ACCELERATION IN 1978-1982 AND THE ASSOCIATED SOLAR-WIND STRUCTURES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY SHOCKS; FORBUSH DECREASES; ENERGETIC PARTICLES; MAGNETIC CLOUDS; DISTURBANCES; EVENTS AB A study has been made of the time histories of particles in the energy range 1 MeV to 1 GeV at the times of all >3% cosmic ray decreases in the years 1978 to 1982. Essentially all of the 59 decreases are associated with passages of interplanetary shocks, the majority of which accelerate particles. We use the intensity-time profiles of the particles to separate the cosmic ray decreases into four classes which we subsequently associate with three types of solar wind structures. Decreases in class 1 (15 events) and class 2 (26 events) are associated with shocks driven by energetic coronal mass ejections. For class 1 events, the ejecta is detected at 1 AU, whereas this is not usually the case for class 2 events. The shock must therefore play a dominant role in producing the cosmic ray depression in class 2 events. In all class 1 and class 2 events (which comprise 69% of the total) the departure time of the ejection from the Sun (and hence the location) can be determined from the rapid onset of energetic particles several days before the associated shock passes the Earth. Class 1 events originate from within 50-degrees of central meridian while class 2 are predominantly from sources beyond 20' from central meridian. Class 3 events (10 decreases) can be attributed to less energetic ejections which are directed towards the Earth. In these events the ejecta is more important than the shock in causing the cosmic ray intensity depression. The remaining events (14% of the total) can be attributed to solar wind periods with multiple disturbances. All include ejecta material and at least half also include corotating high-speed solar wind streams. It is argued that since energetic particles (from MeV to GeV energies) seen at Earth may respond to solar wind structures which are not detected at Earth, consideration of particle observations over a wide range of energies is necessary for a full understanding of cosmic ray decreases. C1 UNIV TASMANIA,DEPT PHYS,HOBART,TAS 7001,AUSTRALIA. UNIV MARYLAND,DEPT PHYS & ASTRON,COLL PK,MD 20742. RP CANE, HV (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 661,GREENBELT,MD 20771, USA. OI Richardson, Ian/0000-0002-3855-3634 NR 29 TC 25 Z9 25 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1993 VL 98 IS A8 BP 13295 EP 13302 DI 10.1029/93JA00955 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LR054 UT WOS:A1993LR05400010 ER PT J AU RICHARDSON, IG OWEN, CJ SLAVIN, JA VONROSENVINGE, TT AF RICHARDSON, IG OWEN, CJ SLAVIN, JA VONROSENVINGE, TT TI ENERGETIC (GREATER-THAN-0.2 MEV) ELECTRON BURSTS OBSERVED BY ISEE-3 IN THE DEEP (LESS-THAN-240 RE) GEOMAGNETIC TAIL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID TRAVELING COMPRESSION REGIONS; APPROXIMATELY 220 RE; EARTHS BOW SHOCK; DISTANT MAGNETOTAIL; BOUNDARY-LAYER; NEAR-EARTH; PLASMA; SUBSTORM; AVERAGE; FLOW AB The Goddard Space Flight Center medium-energy cosmic ray experiment on ISEE 3 made as yet unreported observations of 0.2-2 MeV electrons and >1 MeV/amu ions in the deep geomagnetic tail out to approximately 240 RE from the Earth during the geotail mission in 1982-1983. The most notable feature of these data is the presence of brief (< 1 -hour duration) electron bursts which exceed the instrument background of approximately 0.02 (s cm2 sr MeV)-1. These occur most frequently and have the highest intensities, within approximately 80 RE of the Earth and are relatively absent at greater distances downtail. Approximately 60% of these bursts are observed in the plasma sheet. These occur most frequently on closed field lines connected to the Earth, based on their association with slow earthward or mixed plasma sheet flows and northward directed magnetic fields. The near-absence of such events beyond approximately 80 R(E) downtail provides evidence for predominantly open rather than closed magnetic field structures in the plasma sheet beyond this distance downtail. The observations are consistent with the presence of a distant neutral line in the tail plasma sheet at an average distance of approximately 80 R(E) from the Earth. Approximately 30% of plasma sheet electron bursts are associated with north then south turning magnetic field deviations and fast tailward plasma flows, which may be related to the expulsion of plasmoids following substorm onsets. Approximately 20% of all the electron bursts are seen in the tail lobes, probably associated with encounters with the plasma sheet boundary (separatrix) layer. The lobe events show no clear trend in intensity with downtail distance. We show examples of plasma sheet and lobe electron bursts that are clearly associated with substorms, indicating that temporal as well as spatial variations in the energetic electron intensity do indeed occur in the geomagnetic tail. Finally, approximately 20% of the electron bursts are observed in the magnetosheath. The intensity of magnetosheath bursts also falls off with downtail distance such that they are nearly absent beyond approximately 100 R(E) from the Earth. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP RICHARDSON, IG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 661,GREENBELT,MD 20771, USA. RI Owen, Christopher/C-2999-2008; Slavin, James/H-3170-2012; OI Owen, Christopher/0000-0002-5982-4667; Slavin, James/0000-0002-9206-724X; Richardson, Ian/0000-0002-3855-3634 NR 41 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1993 VL 98 IS A8 BP 13441 EP 13451 DI 10.1029/93JA00501 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LR054 UT WOS:A1993LR05400024 ER PT J AU MENART, JA LEE, HS AF MENART, JA LEE, HS TI NONGRAY GAS-ANALYSES FOR REFLECTING WALLS UTILIZING A FLUX TECHNIQUE SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Article DE RADIATION ID MODEL CALCULATIONS; BAND; H2O AB A flux formulation for a planar slab of molecular gas radiation bounded by diffuse reflecting walls is developed. While this formulation is limited to the planar geometry, it is useful for studying approximations necessary in modeling nongray radiative heat transfer. The governing equations are derived by considering the history of multiple reflections between the walls. Accurate solutions are obtained by explicitly accounting for a finite number of reflections and approximating the spectral effects of the remaining reflections. Four approximate methods are presented and compared using a single absorption band of H2O. All four methods reduce to an identical zeroth-order formulation, which accounts for all reflections approximately but does handle nonreflected radiation correctly. A single absorption band of CO2 is also considered using the best-behaved approximation for higher orders. A zeroth-order formulation is sufficient to predict the radiative transfer accurately for many cases considered. For highly reflecting walls, higher order solutions are necessary for better accuracy. Including all the important bands of H2O, the radiative source distributions are also obtained for two different temperature and concentration profiles. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP MENART, JA (reprint author), UNIV MINNESOTA,DEPT MECH ENGN,MINNEAPOLIS,MN 55455, USA. NR 16 TC 8 Z9 9 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-1481 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD AUG PY 1993 VL 115 IS 3 BP 645 EP 652 DI 10.1115/1.2910735 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LU478 UT WOS:A1993LU47800017 ER PT J AU DRESHFIELD, RL AF DRESHFIELD, RL TI EVALUATION OF MECHANICAL-PROPERTIES OF A LOW-COBALT WROUGHT SUPERALLOY SO JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE LA English DT Article; Proceedings Paper CT 7TH INTERNATIONAL SYMP ON SUPERALLOYS CY SEP 20-24, 1992 CL CHAMPION, PA DE COBALT-BASE, MECHANICAL PROPERTIES; SUPERALLOY; TURBINE BLADE MATERIALS AB In the late 1970s and early 1980s, cobalt was subjected to significant supply and market pressures. Those pressures caused renewed attention to the use of cobalt in aircraft engines. A NASA-sponsored program called Conservation of Strategic Aerospace Materials (COSAM) was created in response to the supply problems with cobalt and other aerospace metals. Among the work performed in the COSAM program and simultaneously by others were several studies on laboratory-size heats of wrought nickel-base super-alloys. These studies suggested that the cobalt levels of the alloys might be reduced by about half, with minimal negative impact on mechanical properties. The Lewis Research Center procured a 1365-kg (3000-lb) heat of a modified Waspaloy having a reduced cobalt level. This article reports the results of a program performed at four gas turbine manufacturers which evaluated the mechanical properties of forgings fabricated from that heat. The alloy chemistry selected reduced the nominal cobalt level from 13.5 to 7.75 wt%. To compensate for the anticipated strength reduction caused by a slight reduction in the amount of gamma', the nominal aluminum was increased from 1.3 to 1.5% and the titanium was increased from 3.0 to 3.2%. The increase in aluminum and titanium were intended to increase the amount of gamma' in the alloy. Tensile, creep-rupture, low-cycle fatigue, and cyclic crack growth tests were performed. In addition the effect of hydrogen on the alloy was determined. It was concluded that, in the event of a cobalt shortage, a low-cobalt modification of Waspaloy alloy could be substituted for Waspaloy with little development in those applications that are not creep-rupture limited. With some additional development to better control the grain size, it is probable that most of the current Waspaloy requirements might be met with a lower cobalt alloy. RP DRESHFIELD, RL (reprint author), NASA,LEWIS RES CTR,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 8 TC 4 Z9 4 U1 1 U2 5 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 1059-9495 J9 J MATER ENG PERFORM JI J. Mater. Eng. Perform. PD AUG PY 1993 VL 2 IS 4 BP 517 EP 522 DI 10.1007/BF02661735 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA LV413 UT WOS:A1993LV41300008 ER PT J AU MILLER, DP LANNUTTI, JJ NOEBE, RD AF MILLER, DP LANNUTTI, JJ NOEBE, RD TI FABRICATION AND PROPERTIES OF FUNCTIONALLY GRADED NIAL AL2O3 COMPOSITES SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID TENSILE AB A modified sedimentation process was used in the production of a functionally gradient material (FGM), NiAl/Al2O3. A simple finite element model was used to guide our design and fabrication efforts by estimating residual stress states as a function of composite structure. This approach could lead to tailored designs that enhance or avoid specific residual stress states. Thermal cycling tests were factored into the model to predict time dependent or steady-state internal temperature and stress profiles. Four-point bend tests were conducted to establish the mechanical load-displacement behavior of a single interlayer FGM at room temperature, 800 and 1000 K. Room temperature bend strength of the FGM was 3-4 times that of the base NiAl. At elevated temperatures, composite fracture occurred in a gradual, noncatastrophic mode involving NiAl retardation of a succession of cracks originating in the alumina face. C1 OHIO STATE UNIV,DEPT MAT SCI & ENGN,COLUMBUS,OH 43210. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 20 TC 28 Z9 28 U1 0 U2 2 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD AUG PY 1993 VL 8 IS 8 BP 2004 EP 2013 DI 10.1557/JMR.1993.2004 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA LR039 UT WOS:A1993LR03900031 ER PT J AU FLAUD, JM CAMYPEYRET, C PERRIN, A DEVI, VM BARBE, A BOUAZZA, S PLATEAUX, JJ RINSLAND, CP SMITH, MAH GOLDMAN, A AF FLAUD, JM CAMYPEYRET, C PERRIN, A DEVI, VM BARBE, A BOUAZZA, S PLATEAUX, JJ RINSLAND, CP SMITH, MAH GOLDMAN, A TI LINE PARAMETERS FOR OZONE HOT BANDS IN THE 3.3-MU-M SPECTRAL REGION SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID LOWER STRATOSPHERE; UPPER TROPOSPHERE; NU-3 BANDS; INTENSITIES; POSITIONS; O-16O-18O-16; O-16O-16O-18; SPACELAB-3; O-16(3); H2O C1 UNIV REIMS,SPECT MOLEC & ATMOSPHER GRP,CNRS,URA 1434,F-51062 REIMS,FRANCE. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. RP FLAUD, JM (reprint author), UNIV PARIS 06,CNRS,PHYS MOLEC & APPLICAT LAB,TOUR 13 BTE 76,4 PL JUSSIEU,F-75252 PARIS 05,FRANCE. NR 24 TC 26 Z9 26 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD AUG PY 1993 VL 160 IS 2 BP 378 EP 386 DI 10.1006/jmsp.1993.1185 PG 9 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA LN758 UT WOS:A1993LN75800008 ER PT J AU PERRIN, A FLAUD, JM CAMYPEYRET, C GOLDMAN, A MURCRAY, FJ BLATHERWICK, RD RINSLAND, CP AF PERRIN, A FLAUD, JM CAMYPEYRET, C GOLDMAN, A MURCRAY, FJ BLATHERWICK, RD RINSLAND, CP TI THE NU(2)-BAND AND 2-NU(2)-NU(2)-BAND OF (NO2)-N-14-O-16 - ELECTRON-SPIN ROTATION AND HYPERFINE CONTACT RESONANCES IN THE (010) VIBRATIONAL-STATE SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID NITROGEN-DIOXIDE; SPECTRUM; MILLIMETER; PARAMETERS; DATABASE; 2-NU-2; BANDS; NO2 C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. RP PERRIN, A (reprint author), UNIV PARIS 06,CNRS,PHYS MOLEC & APPLICAT LAB,BTE 76,4 PL JUSSIEU,F-75252 PARIS 05,FRANCE. NR 23 TC 25 Z9 28 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD AUG PY 1993 VL 160 IS 2 BP 456 EP 463 DI 10.1006/jmsp.1993.1192 PG 8 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA LN758 UT WOS:A1993LN75800015 ER PT J AU FUKUMORI, I BENVENISTE, J WUNSCH, C HAIDVOGEL, DB AF FUKUMORI, I BENVENISTE, J WUNSCH, C HAIDVOGEL, DB TI ASSIMILATION OF SEA-SURFACE TOPOGRAPHY INTO AN OCEAN CIRCULATION MODEL USING A STEADY-STATE SMOOTHER SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Note ID ALTIMETER-DATA; KALMAN FILTER; PACIFIC; WAVES AB The central issue of how to obtain useful, approximate, uncertainty estimates for assimilation methods using full general circulation models is addressed. Such estimates would be used with assimilation done by either sequential methods or Pontryagin principle/adjoint techniques. The problem of computing the error covariances of realistic oceanic general circulation models is explored by finding the asymptotic solutions to the Riccati equations governing Kalman filters and related smoothers. Existence of the steady-state is established through applying the concepts of controllability and observability to a coarse-resolution primitive equation model in the presence of altimetric observations. A ''doubling algorithm'' is then used to solve the Riccati equation. The methodology has the added benefit of rendering sequential estimation methods much less costly. Results are presented for a ''twin experiment'' and for Geosat altimeter data from the North Atlantic Ocean. A realistic altimetric system improves estimates of the depth-dependent (internal mode) circulation, but the improvement of the depth-averaged (external mode) component is limited by the infrequent availability of the present data. The model is found capable of accounting for 6% of the Geosat residual variance; the data residual variance is 43 x 10(-3) m2 (21 cm rms) of which the model accounts for 3 x 10(-3) m2 (5 cm rms), but both model and dataset are crude. C1 MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. RUTGERS UNIV,INST MARINE & COASTAL SCI,NEW BRUNSWICK,NJ 08903. RP FUKUMORI, I (reprint author), JET PROP LAB,MAIL STOP 300-323,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 44 TC 56 Z9 56 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD AUG PY 1993 VL 23 IS 8 BP 1831 EP 1855 DI 10.1175/1520-0485(1993)023<1831:AOSSTI>2.0.CO;2 PG 25 WC Oceanography SC Oceanography GA LT176 UT WOS:A1993LT17600016 ER PT J AU WHEELER, RM MACKOWIAK, CL SIEGRIEST, LM SAGER, JC AF WHEELER, RM MACKOWIAK, CL SIEGRIEST, LM SAGER, JC TI SUPRAOPTIMAL CARBON-DIOXIDE EFFECTS ON GROWTH OF SOYBEAN [GLYCINE-MAX (L) MERR] SO JOURNAL OF PLANT PHYSIOLOGY LA English DT Article DE GLYCINE MAX; CARBON DIOXIDE; CELSS; CO2; CONTROLLED ECOLOGICAL LIFE SUPPORT SYSTEM; STOMATAL CONDUCTANCE; WATER USE EFFICIENCY ID CO2; PHOTOSYNTHESIS; TEMPERATURE; PHYSIOLOGY; ENRICHMENT; EXPOSURE; PLANTS; YIELD AB In tightly closed environments used for human life support in space, carbon dioxide (CO2) partial pressures can reach 500 to 1000 Pa, which may be supraoptimal or toxic to plants used for life support. To study this, soybeans [Glycine max (L.) Merr. cvs. McCall and Pixie] were grown for 90 days at 50, 100, 200, and 500 Pa partial pressure CO2 (500, 1000, 2000, and 5000 ppm). Plants were grown using recirculating nutrient film technique with a 12-h photoperiod, a 26-degrees-C/20-degrees-C thermoperiod, and approximately 300 mumol m-2 s-1 photosynthetic photon flux (PPF). Seed yield and total biomass were greatest at 100 Pa for cv. McCall, suggesting that higher CO2 levels were supraoptimal. Seed yield and total biomass for cv. Pixie showed little difference between CO2 treatments. Average stomatal conductance of upper canopy leaves at 50 Pa CO2 almost-equal-to 500 Pa > 200 Pa > 100 Pa. Total water use over 90 d for both cultivars (combined on one recirculating system) equalled 822 kg water for 100 Pa CO2, 845 kg for 50 Pa, 879 kg for 200 Pa, and 1194kg for 500 Pa. Water use efficiences for both cultivars combined equaled 3.03 (g biomass kg-1 water) for 100 Pa CO2, 2.54 g kg-1 for 200 Pa, 2.42 g kg-1 for 50 Pa, and 1.91 g kg-1 for 500 Pa. The increased stomatal conductance and stand water use at the highest CO2 level (500 Pa) were unexpected and pose interesting considerations,for managing plants in a tightly closed system where CO2 concentrations may reach high levels. C1 BIONET CORP,KENNEDY SPACE CTR,FL 32899. RP WHEELER, RM (reprint author), NASA,BIOL RES & LIFE SUPPORT OFF,MAIL MD-RES,KENNEDY SPACE CTR,FL 32899, USA. NR 24 TC 29 Z9 32 U1 1 U2 1 PU GUSTAV FISCHER VERLAG PI JENA PA VILLENGANG 2, D-07745 JENA, GERMANY SN 0176-1617 J9 J PLANT PHYSIOL JI J. Plant Physiol. PD AUG PY 1993 VL 142 IS 2 BP 173 EP 178 PG 6 WC Plant Sciences SC Plant Sciences GA LW364 UT WOS:A1993LW36400008 PM 11538190 ER PT J AU SIROTA, JM REUTER, DC MUMMA, MJ AF SIROTA, JM REUTER, DC MUMMA, MJ TI INTENSITIES AND BROADENING COEFFICIENTS FOR THE Q-BRANCH OF THE 4-NU(2)[--]NU(1)+NU(2) (471.511CM-1) BAND OF CO2 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article AB Absolute intensities for the Q -branch of the 4nu2 <-- --> nu1 + nu2(1) (20003-11101) band in CO, have been measured for the first time. Measurements were performed for lines Q10 to Q28, at temperatures ranging from 385 to 426 K, for pressures from 3 to 40 torr, using our long wavelength tunable diode laser spectrometer. The combination of tunable diode lasers, a White cell, and a blocked impurity band detector enabled us to obtain signal to noise ratios > 1000 in the 471 cm-1 spectral region, with approximately 3 x 10(-4) cm-1 Spectral resolution. The band strength was found to be 8.6(2) x 10(-25) cm molec-1 @296 K, and the Hermann-Wallis factor was determined. Comparison with the values listed in the HITRAN 92 database are presented. Self-, N2- and O2-broadening coefficients were also measured. RP SIROTA, JM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,CODE 693,GREENBELT,MD 20771, USA. RI mumma, michael/I-2764-2013 NR 7 TC 4 Z9 4 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD AUG PY 1993 VL 50 IS 2 BP 193 EP 198 PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA LN811 UT WOS:A1993LN81100005 ER PT J AU JACOBSON, NS LEE, KN MALOY, SA HEUER, AH AF JACOBSON, NS LEE, KN MALOY, SA HEUER, AH TI CHEMICAL-REACTIONS IN THE PROCESSING OF MOSI2+ CARBON COMPACTS SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID TEMPERATURE MECHANICAL-PROPERTIES; MOLYBDENUM DISILICIDE; ADDITIONS AB Hot-pressing of MoSi2 powders with carbon at high temperatures reduces the siliceous grain boundary phase in the resultant compact. The chemical reactions in this process were examined using the Knudsen cell technique. A 2.3 wt% oxygen MoSi, powder and a 0.59 wt% oxygen MoSi2 powder, both with additions of 2 wt% carbon, were examined. The reduction of the siliceous grain boundary phase was examined at 1350 K and the resultant P(SiO)/P(CO) ratios interpreted in terms of the SiO(g) and CO(g) isobars on the Si-C-O predominance diagram. The MoSi2 + carbon mixtures were then heated at the hot-pressing temperature of 2100 K. Large weight losses were observed and could be correlated with the formation of a low-melting eutectic and the formation and vaporization of SiC. C1 CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106. RP JACOBSON, NS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Jacobson, Nathan/A-9411-2009; Maloy, Stuart/A-8672-2009 OI Maloy, Stuart/0000-0001-8037-1319 NR 13 TC 15 Z9 15 U1 0 U2 4 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD AUG PY 1993 VL 76 IS 8 BP 2005 EP 2009 DI 10.1111/j.1151-2916.1993.tb08324.x PG 5 WC Materials Science, Ceramics SC Materials Science GA LZ615 UT WOS:A1993LZ61500014 ER PT J AU NING, XJ PIROUZ, P FARMER, SC AF NING, XJ PIROUZ, P FARMER, SC TI MICROCHEMICAL ANALYSIS OF THE SCS-6 SILICON-CARBIDE FIBER SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID SIC-FIBER; COMPOSITE AB A detailed quantitative study of the microstructural variation of chemical composition of chemically vapor-deposited commercial SiC SCS-6 fiber is presented. Chemical etching and various electron-optical techniques including scanning electron microscopy, transmission electron microscopy, scanning Auger microscopy, Auger electron spectroscopy, and parallel electron energy loss spectroscopy are used to analyze the chemical composition of the as-received fiber. In addition, some results on stereology of the high-temperature annealed fiber are presented. The results show that the carbon-to-silicon atom ratio in the SiC layers decreases in a stepwise fashion from approximately 3:2 to approximately 1:1 in going from the innermost layer to the outermost layer. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP NING, XJ (reprint author), CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106, USA. NR 17 TC 22 Z9 22 U1 0 U2 2 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD AUG PY 1993 VL 76 IS 8 BP 2033 EP 2041 DI 10.1111/j.1151-2916.1993.tb08329.x PG 9 WC Materials Science, Ceramics SC Materials Science GA LZ615 UT WOS:A1993LZ61500019 ER PT J AU SAKHAEE, K HARVEY, JA PADALINO, PK WHITSON, P PAK, CYC AF SAKHAEE, K HARVEY, JA PADALINO, PK WHITSON, P PAK, CYC TI THE POTENTIAL ROLE OF SALT ABUSE ON THE RISK FOR KIDNEY-STONE FORMATION SO JOURNAL OF UROLOGY LA English DT Article DE URINARY CALCULI; KIDNEY CALCULI; SODIUM; DIET, SODIUM-RESTRICTED ID CALCIUM-OXALATE; IDIOPATHIC HYPERCALCIURIA; CITRATE; UROLITHIASIS; FORMERS; SODIUM; STATE; URINE AB The kidney stone-forming risk of a high sodium diet was evaluated by assessing the effect of such a diet on the crystallization of stone-forming salts in urine. Fourteen normal subjects participated in 2 phases of study of 10 days duration each, comprising a low sodium phase (basal metabolic diet containing 50 mmol. sodium per day) and a high sodium phase (basal diet plus 250 mmol. sodium chloride per day). The high sodium intake significantly increased urinary sodium (34 +/- 12 to 267 +/- 56 mmol. per day), calcium (12.73 +/- 1.03 to 3.93 +/- 1.51 mmol. per day) and pH (5.79 +/- 0.44 to 6.15 +/- 0.25), and significantly decreased urinary citrate (3.14 +/- 1.19 to 2.52 +/- 0.83 mmol. per day). Arterialized venous blood bicarbonate and total serum carbon dioxide concentrations decreased significantly during the high sodium diet, whereas serum chloride concentration increased. However, no change in arterialized venous pH was detected. Thus, a high sodium intake not only increased calcium excretion, but also increased urinary pH and decreased citrate excretion. The latter effects are probably due to sodium-induced bicarbonaturia and a significant decrease in serum bicarbonate concentration, respectively. Commensurate with these changes, the urinary saturation of calcium phosphate (brushite) and monosodium urate increased, and the inhibitor activity against calcium oxalate crystallization (formation product) decreased. The net effect of a high sodium diet was an increased propensity for the crystallization of calcium salts in urine. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP SAKHAEE, K (reprint author), UNIV TEXAS,SW MED CTR,SW MED SCH,CTR MINERAL METAB & CLIN RES,DALLAS,TX 75235, USA. FU NCRR NIH HHS [M01-RR00633]; NIDDK NIH HHS [P01-DK20543] NR 25 TC 112 Z9 119 U1 6 U2 15 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0022-5347 J9 J UROLOGY JI J. Urol. PD AUG PY 1993 VL 150 IS 2 BP 310 EP 312 PN 1 PG 3 WC Urology & Nephrology SC Urology & Nephrology GA LM765 UT WOS:A1993LM76500003 PM 8326549 ER PT J AU NAKAYAMA, A FABRIS, G AF NAKAYAMA, A FABRIS, G TI TRANSPORT-EQUATIONS OF CONDITIONALLY AVERAGED REYNOLDS STRESSES FOR COMPUTATION OF TURBULENT FLOWS WITH INTERMITTENCY SO JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS LA English DT Article; Proceedings Paper CT 1ST INTERNATIONAL SYMP ON COMPUTATIONAL WIND ENGINEERING ( CWE92 ) CY AUG 21-23, 1992 CL UNIV TOKYO, TOKYO, JAPAN SP JAPAN ASSOC WIND ENGN, UNIV TOKYO, INST IND SCI HO UNIV TOKYO ID MODEL AB The transport equations for conditionally averaged Reynolds stresses have been derived for use in computation of turbulent flows with intermittency. In addition to terms corresponding to those appearing in conventional transport equations, the conditional transport equations involve entrainment and interaction terms arising from the time-sharing of different zones of intermittent flows. The new terms have been examined using available experimental data taken in interacting shear flows. Careful treatment of these terms is generally required for proper modelling. In certain cases, however, the magnitudes of the total of the extra terms are small and the evolution of the conditional Reynolds stresses are little influenced by the existence of the other zone. C1 JET PROP LAB,PASADENA,CA 91109. RP NAKAYAMA, A (reprint author), KOBE UNIV,KOBE 657,JAPAN. NR 13 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-6105 J9 J WIND ENG IND AEROD JI J. Wind Eng. Ind. Aerodyn. PD AUG PY 1993 VL 46-7 BP 155 EP 164 DI 10.1016/0167-6105(93)90125-8 PG 10 WC Engineering, Civil; Mechanics SC Engineering; Mechanics GA LY577 UT WOS:A1993LY57700016 ER PT J AU GOLUB, MA LOPATA, ES FINNEY, LS AF GOLUB, MA LOPATA, ES FINNEY, LS TI X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF THE EFFECT OF HYDROCARBON CONTAMINATION ON POLY(TETRAFLUOROETHYLENE) EXPOSED TO A NITROGEN PLASMA SO LANGMUIR LA English DT Note ID OXYGEN PLASMA; ESCA C1 HIMONT PLASMA SCI,FOSTER CITY,CA 94404. SURFACE SCI LABS,MT VIEW,CA 94043. RP GOLUB, MA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 10 TC 9 Z9 9 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0743-7463 J9 LANGMUIR JI Langmuir PD AUG PY 1993 VL 9 IS 8 BP 2240 EP 2242 DI 10.1021/la00032a056 PG 3 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA LU396 UT WOS:A1993LU39600056 ER PT J AU WALSH, JL LAMARSH, WJ ADELMAN, HM AF WALSH, JL LAMARSH, WJ ADELMAN, HM TI FULLY INTEGRATED AERODYNAMIC DYNAMIC OPTIMIZATION OF HELICOPTER ROTOR BLADES SO MATHEMATICAL AND COMPUTER MODELLING LA English DT Article AB This paper describes a fully integrated aerodynamic/dynamic optimization procedure for helicopter rotor blades. The procedure combines performance and dynamics analyses with a general purpose optimizer. The procedure minimizes a linear combination of power required (in hover, forward flight, and maneuver) and vibratory hub shear. The design variables include pretwist, taper initiation, taper ratio, root chord, blade stiffnesses, tuning masses, and tuning mass locations. Performance constraints consist of limits on power required in hover, forward flight, maneuver, airfoil section stall, drag-divergence Mach number, minimum tip chord, and trim. Dynamic constraints are on blade natural frequencies, minimum autorotational inertia, and maximum blade weight. The procedure is demonstrated for two cases. In the first case, the objective function involves power required (in hover, forward flight, and maneuver) and vibratory hub shear. In the second case, the objective function involves power required in hover and vibratory hub shear. For both cases, the designs from the integrated procedure are compared with designs from a sequential optimization approach. In the sequential optimization approach, the blade is optimized first for performance (minimum power) using only aerodynamic design variables and performance constraints. Then these optimized aerodynamic design variables are held fixed, and the blade is optimized for minimum vibratory hub shear, using only dynamic design variables and dynamic constraints. In both cases, the integrated approach is superior to the sequential approach. C1 UNISYS CORP,HAMPTON,VA. RP WALSH, JL (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 23 TC 5 Z9 5 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0895-7177 J9 MATH COMPUT MODEL JI Math. Comput. Model. PD AUG PY 1993 VL 18 IS 3-4 BP 53 EP 72 DI 10.1016/0895-7177(93)90104-7 PG 20 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA MD773 UT WOS:A1993MD77300005 ER PT J AU CHATTOPADHYAY, A MCCARTHY, TR MADDEN, JF AF CHATTOPADHYAY, A MCCARTHY, TR MADDEN, JF TI STRUCTURAL OPTIMIZATION OF HIGH-SPEED PROP ROTORS INCLUDING AEROELASTIC STABILITY CONSTRAINTS SO MATHEMATICAL AND COMPUTER MODELLING LA English DT Article AB An optimization procedure is developed to address the problem of aeroelastic stability of high speed prop-rotor aircraft. A composite box beam is used as a perturbational stiffness model and the objective function to be minimized is the perturbational weight. An optimization algorithm, which used the method of feasible directions, is coupled with a hybrid approximate analysis to reduce the computational expense of exact analyses for every function evaluation. The results, compared to a reference rotor which is unstable in both hover and high speed cruise, show significant improvements in the aeroelastic stability without large weight penalties. C1 NASA,AMES RES CTR,ROTORCRAFT TECHNOL BRANCH,MOFFETT FIELD,CA 94035. RP CHATTOPADHYAY, A (reprint author), ARIZONA STATE UNIV,DEPT MECH & AEROSP ENGN,TEMPE,AZ 85287, USA. NR 27 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0895-7177 J9 MATH COMPUT MODEL JI Math. Comput. Model. PD AUG PY 1993 VL 18 IS 3-4 BP 101 EP 113 DI 10.1016/0895-7177(93)90107-A PG 13 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA MD773 UT WOS:A1993MD77300008 ER PT J AU KEYSER, LF LEU, MT AF KEYSER, LF LEU, MT TI MORPHOLOGY OF NITRIC-ACID AND WATER ICE FILMS SO MICROSCOPY RESEARCH AND TECHNIQUE LA English DT Article DE ESEM; SURFACE REACTION; POLAR STRATOSPHERIC CLOUDS ID HETEROGENEOUS REACTIONS; HYDROGEN-CHLORIDE; OZONE HOLE; TRIHYDRATE; NITRATE; HCL AB Ice films have been used to simulate stratospheric cloud surfaces in order to obtain laboratory data on solubilities and heterogeneous reaction rates. To obtain intrinsic uptake and surface reaction probabilities which can be applied to atmospheric models, it is necessary to carefully characterize these films. In the present study, environmental scanning electron microscopy (ESEM) is used to study thin films of both water ice and nitric acid ice near the composition of the trihydrate. The ices are formed by vapor deposition onto aluminum or borosilicate-glass substrates cooled to about 200 K. Micrographs are recorded during the deposition process and during subsequent annealing at higher temperatures. The results show that the ice films are composed of loosely consolidated granules, which range from about 1 to 20 mum in size at temperatures between 197 and 235 K. Cubic water ice is sometimes observed at 200 K and converts to the hexagonal form at slightly higher temperatures. The loose packing of the granules confirms the high porosities of these films obtained from separate bulk porosity measurements. Average surface areas calculated from the observed granule sizes range from about 0.2 to 1 m2 g-1 and agree with surface areas obtained by gas-adsorption (BET) analysis of annealed ice films. For unannealed films, the BET areas are about an order of magnitude higher than the ESEM results and imply that the unannealed ices contain microporosity which is lost during the annealing process. The present results have important implications for the extraction of intrinsic reaction probabilities from laboratory rate data. (C) 1993 Wiley-Liss, Inc. RP KEYSER, LF (reprint author), JET PROP LAB,DIV EARTH & SPACE SCI,MAIL STOP 183-901,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 16 TC 36 Z9 36 U1 0 U2 5 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 1059-910X J9 MICROSC RES TECHNIQ JI Microsc. Res. Tech. PD AUG PY 1993 VL 25 IS 5-6 BP 434 EP 438 DI 10.1002/jemt.1070250514 PG 5 WC Anatomy & Morphology; Biology; Microscopy SC Anatomy & Morphology; Life Sciences & Biomedicine - Other Topics; Microscopy GA LN846 UT WOS:A1993LN84600013 PM 8400437 ER PT J AU SMITH, RG SELLGREN, K BROOKE, TY AF SMITH, RG SELLGREN, K BROOKE, TY TI GRAIN MANTLES IN THE TAURUS DARK CLOUD SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE MOLECULAR PROCESSES; STARS LATE-TYPE; ISM CLOUDS; DUST, EXTINCTION; INFRARED GENERAL ID INTER-STELLAR DUST; INTERSTELLAR GRAINS; MOLECULAR CLOUD; OPTICAL-PROPERTIES; CARBON-MONOXIDE; INFRARED-SPECTROSCOPY; SIZE DISTRIBUTION; SILICATE GRAINS; ICE FEATURE; SOLID CO AB We have obtained low-resolution (lambda/DELTAlambda approximately 160) 3-mum spectra of a selection of field stars lying behind the Taurus dark cloud. Several of these stars have abnormal extinction laws, which are best characterized by A(K) less-than-or-equal-to 0.27E(J-K) and A(V) less-than-or-equal-to 5.4 E (J-K). We find a very good correlation between A(V) and tau3.05 (the H2O ice feature), confirming a previous result, and between A(V) and tau3.45 (the long-wavelength wing), yielding the ratios tau3.05/A(V)=0.059+/-0.003 and tau3.45/A(V)=0.0077+/-0.0005. The threshold extinctions for the H2O ice band and the long-wavelength wing are found to be the same, within the uncertainties, at A(V0) = 2.6. The fact that these thresholds are the same means that the long-wavelength wing cannot be a result of a highly refractory hydrocarbon residue. The lack of substructure in the long-wavelength wing also argues against a hydrocarbon origin for the wing. By interpreting the H2O ice feature with a model employing silicate and graphite grain cores that follow a power-law size distribution, we find that the ice band observations can only be fitted by models in which either (i) only the largest grains have significant ice mantles, or (ii) there are two grain populations throughout the cloud, one of 'bare' grains and one of grains that have a constant ice mantle thickness of 0.35+/-0.05 mum. In the latter model, we estimate the ratio of bare to mantled grains to be approximately 3 x 10(4):1. Both models, combined with the observed tau3.05/A(V) ratio, imply that 8-9 per cent of the oxygen is depleted on to the grains as H2O ice mantles. We discuss a number of mechanisms for the production of the H2O ice and long-wavelength wing thresholds, and conclude that photodesorption is the most likely means of prevention of H2O ice mantle formation near the cloud edges. Photodesorption, combined with a clumpy cloud structure, also naturally explains the bare/mantled grain distribution, as UV photons penetrating into the cloud prevent ice mantle formation everywhere except within dense clumps. C1 OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. JET PROP LAB,PASADENA,CA 91109. RP SMITH, RG (reprint author), UNIV NEW S WALES,UNIV COLL,DEPT PHYS,CANBERRA,ACT 2600,AUSTRALIA. NR 61 TC 90 Z9 90 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 1 PY 1993 VL 263 IS 3 BP 749 EP 766 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP311 UT WOS:A1993LP31100024 ER PT J AU TELESCO, CM AF TELESCO, CM TI STRONG LIMITS ON THE 20-MU-M EMISSION FROM THE HIGH-REDSHIFT GALAXY IRAS 10214+4724 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Letter DE GALAXIES INDIVIDUAL IRAS 10214+4724; GALAXIES PHOTOMETRY; GALAXIES STARBURST; INFRARED GALAXIES AB We report new observations at 20 mum of the high-redshift galaxy IRAS 10214 + 4724 which, if the previous identification is correct, is the most luminous object known. In 6.6 h of integration time using the Infrared Telescope Facility bolometer, we determined the flux density to be 12 +/- 8 mJy. Combination of this measurement with a published one made with the same instrument results in a 3sigma upper limit of 23 mJy at 20.0 mum. This strong limit is markedly inconsistent with that expected for this galaxy using published starburst models which fit well the infrared spectral energy distribution at other wavelengths. However, we show that the spectral energy distribution incorporating our result is similar to those of some galaxies that are experiencing intense starbursts, and so our new results provide a basis for modification of the models. RP TELESCO, CM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES63,HUNTSVILLE,AL 35812, USA. NR 12 TC 8 Z9 8 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 1 PY 1993 VL 263 IS 3 BP L37 EP L39 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP311 UT WOS:A1993LP31100003 ER PT J AU CHANG, ATC CHIU, LS WILHEIT, TT AF CHANG, ATC CHIU, LS WILHEIT, TT TI RANDOM ERRORS OF OCEANIC MONTHLY RAINFALL DERIVED FROM SSM-I USING PROBABILITY-DISTRIBUTION FUNCTIONS SO MONTHLY WEATHER REVIEW LA English DT Article ID MICROWAVE AB Global averages and random errors associated with the monthly oceanic rain rates derived from the Special Sensor Microwave/Imager (SSM/I) data using the technique developed by Wilheit et al. are computed. Accounting for the beam-filling bias, a global annual average rain rate of 1.26 m is computed. The error estimation scheme is based on the existence of independent (morning and afternoon) estimates of the monthly mean. Calculations show overall random errors of about 50%-60% for each 5-degrees X 5-degrees box. The results are insensitive to different sampling strategy (odd and even days of the month). Comparison of the SSM/I estimates with raingage data collected at the Pacific atoll stations showed a low bias of about 8%, a correlation of 0.7. and an rms difference of 55%. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. GEN SCI CORP,LAUREL,MD. TEXAS A&M UNIV SYST,DEPT METEOROL,COLL STN,TX 77843. RI Wilheit, Thomas/G-9438-2012 NR 13 TC 26 Z9 26 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD AUG PY 1993 VL 121 IS 8 BP 2351 EP 2354 DI 10.1175/1520-0493(1993)121<2351:REOOMR>2.0.CO;2 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP877 UT WOS:A1993LP87700011 ER PT J AU MASK, G LANE, HW AF MASK, G LANE, HW TI SELECTED MEASURES OF SELENIUM STATUS IN FULL-TERM AND PRETERM NEONATES, THEIR MOTHERS AND NONPREGNANT WOMEN SO NUTRITION RESEARCH LA English DT Article DE SELENIUM; PREMATURE NEONATES; GLUTATHIONE PEROXIDASE; PLATELET GLUTATHIONE PEROXIDASE ID GLUTATHIONE-PEROXIDASE-ACTIVITY; SUPPLEMENTAL-FOOD PROGRAM; SELF-SELECTED DIETS; PREGNANT-WOMEN; BLOOD SELENIUM; CORD BLOOD; INFANTS; GROWTH; NUTRIENT; PLASMA AB The purpose of this study was to determine selenium status in five subject groups: 13 premature neonates (30-35 wk gestation) and their mothers (17-40 y), 15 full-term neonates (38-43 wk gestation) and their mothers (17-39 y), and 15 women aged 17 to 40 years who were not pregnant. Macronutrient and selenium consumption was estimated from the women's recall of a typical day's diet. The concentration of selenium in plasma, and the specific activity of glutathione peroxidase in red blood cells and in platelet-rich plasma (PRP), were measured in blood samples from control subjects and in maternal and umbilical-cord blood samples taken at delivery. Selenium intake, plasma selenium, and red blood cell glutathione-peroxidase activity were not different among the 3 adult groups. Full-term neonates had more selenium in plasma than the premature neonates, possibly because of accumulation of this element during gestation. PRP glutathione-peroxidase activity was significantly less in the full-term mothers than in the control subjects. Also, the full-term neonates had less PRP glutathione-peroxidase activity than the premature neonates. These biochemical differences seem to reflect physiological changes associated with pregnancy and gestational age. C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,MAIL CODE SD4,HOUSTON,TX 77058. AUBURN UNIV,DEPT NUTR & FOODS,AUBURN,AL 36849. NR 49 TC 9 Z9 10 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0271-5317 J9 NUTR RES JI Nutr. Res. PD AUG PY 1993 VL 13 IS 8 BP 901 EP 911 DI 10.1016/S0271-5317(05)80593-7 PG 11 WC Nutrition & Dietetics SC Nutrition & Dietetics GA LQ418 UT WOS:A1993LQ41800006 ER PT J AU LAHR, TF HARRISON, LK AF LAHR, TF HARRISON, LK TI ONLINE ACCESS TO INTERNATIONAL AEROSPACE SCIENCE AND TECHNOLOGY SO ONLINE & CDROM REVIEW LA English DT Meeting Abstract C1 NASA,STI PROGRAM,WASHINGTON,DC 20546. NR 0 TC 0 Z9 0 U1 0 U2 2 PU LEARNED INFORMATION LTD PI OXFORD PA WOODSIDE, HINKSEY HILL, OXFORD, ENGLAND OX1 5AU SN 1353-2642 J9 ONLINE CDROM REV JI Online Cdrom Rev. PD AUG PY 1993 VL 17 IS 4 BP 255 EP 255 PG 1 WC Computer Science, Information Systems; Information Science & Library Science SC Computer Science; Information Science & Library Science GA NP658 UT WOS:A1993NP65800019 ER PT J AU HEANEY, JB BRADLEY, SE BLY, VT EWIN, AJ LA, AT AF HEANEY, JB BRADLEY, SE BLY, VT EWIN, AJ LA, AT TI ORDER-SORTING FILTER TRANSMITTANCE MEASURED WITH AN ARRAY DETECTOR SO OPTICAL ENGINEERING LA English DT Article DE ORDER-SORTING FILTERS; GRATING SPECTROMETERS; ARRAY DETECTORS; SPATIAL UNIFORMITY; LINE SPREAD FUNCTION AB The simultaneous measurement of the spectrally and spatially variant transmittance of a linear variable order-sorting filter in a manner that closely resembles its conditions of actual use is described. The transmittance of a prototype order-sorting filter was measured in the 400-to 880-nm wavelength region by illuminating it with the output beam of a spectrophotometer while the filter was attached to the front of a 30 x 32 pixel silicon array detector. The filter was designed to be used in the output beam of a grating spectrometer to prevent the dispersal of higher diffracted orders onto an array detector. Areas of the filter that were spatially matched to the corresponding detector pixel column had measured peak transmittances of about 90% that were uniform to within +/-1.5% along a given column. Transmittances for incident wavelengths shorter than the desired bandpass, corresponding to the order overlap region, were measured in the 3 x 10(-3) range. Line spread function measurements made with the array detector indicated no significant beam spreading caused by inserting the filter into the beam. C1 NASA,GODDARD SPACE FLIGHT CTR,OPT RES BRANCH,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,DETECTORS SYST SECT,GREENBELT,MD 20771. RP HEANEY, JB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OPT BRANCH,INFRARED & CRYOOPT LAB,GREENBELT,MD 20771, USA. NR 8 TC 0 Z9 1 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD AUG PY 1993 VL 32 IS 8 BP 1827 EP 1834 DI 10.1117/12.143302 PG 8 WC Optics SC Optics GA LR112 UT WOS:A1993LR11200021 ER PT J AU DOWNIE, JD AF DOWNIE, JD TI OPTIMAL BINARY PHASE AND AMPLITUDE CORRELATION FILTERS FOR POLARIZATION-ROTATING SPATIAL LIGHT MODULATORS SO OPTICAL ENGINEERING LA English DT Article DE OPTICAL CORRELATORS; OPTICAL PATTERN RECOGNITION; BINARY PHASE FILTERS ID IMPROVED CORRELATION DISCRIMINATION; ONLY FILTERS; RATIO AB We investigate the optimal designs of binary phase and amplitude filters (BPAFs) for the key correlation metrics of peak intensity, peak-to-correlation energy, SNR, and discrimination. These filters may be implemented on binary polarization-rotating spatial light modulators. We present simulation results comparing performance to conventional binary phase-only filters (BPOFs) and illustrating trade-offs between the different performance criteria in terms of the filter design parameter. We also extend the generalization to three-level phase and amplitude filters with a nonzero region of support and demonstrate that optimal three-level BPAFs can provide clearly superior performance to optimal three-level BPOFs. RP DOWNIE, JD (reprint author), NASA,AMES RES CTR,MAIL STOP 269-3,MOFFETT FIELD,CA 94035, USA. NR 24 TC 3 Z9 3 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD AUG PY 1993 VL 32 IS 8 BP 1886 EP 1896 DI 10.1117/12.145602 PG 11 WC Optics SC Optics GA LR112 UT WOS:A1993LR11200031 ER PT J AU AUSTIN, RA RAMSEY, BD AF AUSTIN, RA RAMSEY, BD TI OPTICAL IMAGING CHAMBER FOR X-RAY ASTRONOMY SO OPTICAL ENGINEERING LA English DT Article DE X-RAY ASTRONOMY; IMAGING; POLARIMETRY AB The light emitted by electron avalanches in a parallel plate chamber can be used to image the tracks of photoelectrons liberated by the interaction of an incident-x-ray with the gas filling the chamber. The differing morphologies of photoelectron tracks and high-energy charged particle tracks can be used for background rejection. The initial direction (before scattering) of the liberated photoelectron also contains information about the polarization of the incident radiation. We have built a small test chamber with which we have imaged photoelectron tracks using an intensified CCD camera. Our results show that optical imaging could be used in a hard x-ray imaging polarimeter useful for astronomy. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP AUSTIN, RA (reprint author), HUGHES STX CORP,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,BLDG 4481,ES 65,HUNTSVILLE,AL 35812, USA. NR 4 TC 13 Z9 13 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD AUG PY 1993 VL 32 IS 8 BP 1990 EP 1994 DI 10.1117/12.147148 PG 5 WC Optics SC Optics GA LR112 UT WOS:A1993LR11200043 ER PT J AU KOCH, GJ DEYST, JP STORM, ME AF KOCH, GJ DEYST, JP STORM, ME TI SINGLE-FREQUENCY LASING OF MONOLITHIC HO, TM-YLF SO OPTICS LETTERS LA English DT Article ID LASER AB Single-frequency lasing in monohtluc crystals of holmium-thulium-doped YLF (Ho,Tm:YLF) is reported. A maximum single-frequency output power of 6 mW at a wavelength of 2.05 mum is demonstrated. Frequency tuning is also described. C1 NATL INST STAND & TECHNOL,GAITHERSBURG,MD 20879. HUGHES STX CORP,SEAFORD,VA 23696. RP KOCH, GJ (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 11 TC 54 Z9 58 U1 1 U2 8 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD AUG 1 PY 1993 VL 18 IS 15 BP 1235 EP 1237 DI 10.1364/OL.18.001235 PG 3 WC Optics SC Optics GA LP287 UT WOS:A1993LP28700011 PM 19823343 ER PT J AU WELCH, RB BRIDGEMAN, B ANAND, S BROWMAN, KE AF WELCH, RB BRIDGEMAN, B ANAND, S BROWMAN, KE TI ALTERNATING PRISM EXPOSURE CAUSES DUAL ADAPTATION AND GENERALIZATION TO A NOVEL DISPLACEMENT SO PERCEPTION & PSYCHOPHYSICS LA English DT Article AB In two experiments, we examined the hypothesis that repeatedly adapting and readapting to two mutually conflicting sensory environments fosters the development of a separate adaptation to each situation (dual adaptation) as well as an increased ability to adapt to a novel displacement (adaptive generalization). In the preliminary study, subjects alternated between adapting their visuomotor coordination to 30-diopter prismatic displacement and readapting to normal vision. Dual adaptation was observed by the end of 10 alternation cycles. However, an unconfounded test of adaptive generalization was prevented by an unexpected prism-adaptive shift in preexposure baselines for the dual-adapted subjects. In the primary experiment, the subjects adapted and readapted to opposite 15-diopter displacements for a total of 12 cycles. Both dual adaptation and adaptive generalization to a 30-diopter displacement were obtained. These findings may be understood in terms of serial reversal learning and ''learning to learn.'' C1 UNIV CALIF SANTA CRUZ,SANTA CRUZ,CA 95064. RP WELCH, RB (reprint author), NASA,AMES RES CTR,MAIL STOP 239-11,MOFFETT FIELD,CA 94035, USA. NR 25 TC 131 Z9 131 U1 2 U2 4 PU PSYCHONOMIC SOC INC PI AUSTIN PA 1710 FORTVIEW RD, AUSTIN, TX 78704 SN 0031-5117 J9 PERCEPT PSYCHOPHYS JI Percept. Psychophys. PD AUG PY 1993 VL 54 IS 2 BP 195 EP 204 DI 10.3758/BF03211756 PG 10 WC Psychology; Psychology, Experimental SC Psychology GA LM887 UT WOS:A1993LM88700008 PM 8361835 ER PT J AU MORELLI, DT PERRY, TA VANDERSANDE, JW UHER, C AF MORELLI, DT PERRY, TA VANDERSANDE, JW UHER, C TI GLASSLIKE THERMAL TRANSPORT IN HEAVILY IRRADIATED DIAMOND SO PHYSICAL REVIEW B LA English DT Article ID AMORPHOUS-CARBON FILMS; CONDUCTIVITY; CRYSTALS; QUARTZ; DEPOSITION; GLASSES; SOLIDS; HEAT AB We have studied the thermal conductivity K of heavily neutron-irradiated diamond from 0.15 K to room temperature. X-ray and Raman-scattering results indicate that this material is a mixture of sp2- and sp3-bonded carbon and amorphous in nature. The thermal conductivity is similar in temperature dependence to that of a glass with a high Debye temperature. The magnitude of K, however, is larger than that predicted by standard models of heat conduction in disordered solids. This may arise due to the strong covalent bonding in diamond. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. UNIV MICHIGAN,DEPT PHYS,ANN ARBOR,MI 48109. RP MORELLI, DT (reprint author), GM CORP,RES,DEPT PHYS,WARREN,MI 48090, USA. NR 24 TC 11 Z9 11 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD AUG 1 PY 1993 VL 48 IS 5 BP 3037 EP 3041 DI 10.1103/PhysRevB.48.3037 PG 5 WC Physics, Condensed Matter SC Physics GA LQ989 UT WOS:A1993LQ98900021 ER PT J AU STOLORZ, P AF STOLORZ, P TI RECURSIVE APPROACHES TO THE ANALYSIS OF SHORT-RANGE DISORDED SYSTEMS IN THE LOW-TEMPERATURE REGIME SO PHYSICAL REVIEW B LA English DT Article ID ISING SPIN-GLASSES; STATISTICAL-MECHANICS; MAGNETIC-FIELD; MONTE-CARLO; MEAN-FIELD; LATTICE; MODEL; OPTIMIZATION; DIMENSIONS; BEHAVIOR AB Extensions of transfer-matrix methods are presented for reconstructing the complete set of low-energy states for finite-size short-range discrete-spin lattice models, allowing accurate low-temperature calculations on lattices of small size, unhindered by equilibration problems. A version that reconstructs every ground state is applied to calculate the order-parameter distribution at T=0 for the three-dimensional nearest-neighbor +/-J Ising spin glass on lattice sizes up to 4(3). The methods can also be applied to a number of problems in chemistry and biology, especially the study of macromolecular structure. C1 SANTA FE INST,SANTA FE,NM 87501. RP STOLORZ, P (reprint author), JET PROP LAB,MS 198-219,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 33 TC 0 Z9 0 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD AUG 1 PY 1993 VL 48 IS 5 BP 3085 EP 3089 DI 10.1103/PhysRevB.48.3085 PG 5 WC Physics, Condensed Matter SC Physics GA LQ989 UT WOS:A1993LQ98900028 ER PT J AU JOHN, S TOWNSEND, LW WILSON, JW TRIPATHI, RK AF JOHN, S TOWNSEND, LW WILSON, JW TRIPATHI, RK TI GEOMETRIC MODEL FOR NUCLEAR ABSORPTION FROM MICROSCOPIC THEORY SO PHYSICAL REVIEW C LA English DT Article ID REACTION CROSS-SECTIONS; HEAVY-ION COLLISIONS; SCATTERING; DENSITY AB A parameter-free geometric model for nuclear absorption is derived from microscopic theory. The expression for the absorption cross section in the eikonal approximation taken in integral form is separated into a geometric contribution, described by an energy-dependent effective radius, and two surface terms which are shown to cancel in an asymptotic series expansion. For collisions of light nuclei, an expression for the effective radius is derived using harmonic-oscillator nuclear density functions. A direct extension to heavy nuclei with Woods-Saxon densities is made by identifying the equivalent half density radius for the harmonic-oscillator functions. Coulomb corrections are incorporated and a simplified geometric form of the Bradt-Peters type obtained. Results spanning the energy range of 1 MeV/nucleon to 1 GeV/nucleon are presented. Good agreement with experimental results are obtained. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP JOHN, S (reprint author), VIGYAN INC,30 RES DR,HAMPTON,VA 23666, USA. NR 33 TC 15 Z9 15 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD AUG PY 1993 VL 48 IS 2 BP 766 EP 773 DI 10.1103/PhysRevC.48.766 PG 8 WC Physics, Nuclear SC Physics GA LT233 UT WOS:A1993LT23300042 PM 9968888 ER PT J AU KHAN, F TOWNSEND, LW TRIPATHI, RK CUCINOTTA, FA AF KHAN, F TOWNSEND, LW TRIPATHI, RK CUCINOTTA, FA TI UNIVERSAL CHARACTERISTICS OF TRANSVERSE-MOMENTUM TRANSFER IN INTERMEDIATE-ENERGY HEAVY-ION COLLISIONS SO PHYSICAL REVIEW C LA English DT Note ID COLLECTIVE MOTION; HADRONIC MATTER; FLOW; DISAPPEARANCE; NUCLEON AB A microscopic optical model formalism for estimating momentum transfer in intermediate energy heavy ion collisions predicts universal behavior of the transverse component. In particular, for symmetric systems (A(p) = A(T)) heavier than niobium, it appears that values of P(perpendicular-to)/A are independent of the mass and charge of the colliding nuclei and vary only with impact parameter and incident beam energy. This suggests that momentum transfer per nucleon saturates to some limiting value with increasing mass. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. VIGYAN INC,HAMPTON,VA 23666. RP KHAN, F (reprint author), OLD DOMINION UNIV,NORFOLK,VA 23529, USA. NR 28 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 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD AUG PY 1993 VL 48 IS 2 BP 926 EP 928 DI 10.1103/PhysRevC.48.926 PG 3 WC Physics, Nuclear SC Physics GA LT233 UT WOS:A1993LT23300063 PM 9968909 ER PT J AU KHAN, F TOWNSEND, LW AF KHAN, F TOWNSEND, LW TI WIDTHS OF TRANSVERSE-MOMENTUM DISTRIBUTIONS IN INTERMEDIATE-ENERGY HEAVY-ION COLLISIONS SO PHYSICAL REVIEW C LA English DT Note ID FRAGMENTATION; PROJECTILES AB The need to include dynamical collision momentum transfer contributions, arising from interacting nuclear and Coulomb fields, to estimates of fragment momentum distributions is discussed. Methods based upon an optical potential model are presented. Comparisons with recent experimental data of the Siegen group for variances of transverse momentum distributions for gold nuclei at 980 A MeV fragmenting on silver foil and plastic nuclear track detector targets are made. The agreement between theory and experiment is good. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP KHAN, F (reprint author), OLD DOMINION UNIV,DEPT PHYS,NORFOLK,VA 23529, USA. NR 24 TC 10 Z9 10 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD AUG PY 1993 VL 48 IS 2 BP R513 EP R517 DI 10.1103/PhysRevC.48.R513 PG 5 WC Physics, Nuclear SC Physics GA LT233 UT WOS:A1993LT23300008 PM 9968922 ER PT J AU MAHLON, G YAN, TM DUNN, C AF MAHLON, G YAN, TM DUNN, C TI GENERALIZED GLUON CURRENTS AND APPLICATIONS IN QCD SO PHYSICAL REVIEW D LA English DT Article ID GAUGE-THEORIES; MULTIPLE BREMSSTRAHLUNG; HIGH-ENERGIES; HELICITY AMPLITUDES; PARTON PROCESSES; SCATTERING; SUBPROCESS; QUARK AB We present a recursion relation for a current containing n off-shell plus an arbitrary number of on-shell gluons. We are able to obtain an exact solution for n=2 when all of the on-shell gluons have the same helicity, and one of the off-shell gluons is given a ''generalized'' polarization vector. We then apply this solution to derive an expression for the amplitude for qqBAR --> qqggBAR ... g. C1 CORNELL UNIV,NEWMAN LAB NUCL STUDIES,ITHACA,NY 14853. JET PROP LAB,PASADENA,CA 91109. RP MAHLON, G (reprint author), FERMILAB NATL ACCELERATOR LAB,DEPT THEORET PHYS,MS 106,POB 500,BATAVIA,IL 60510, USA. NR 40 TC 10 Z9 10 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD AUG 1 PY 1993 VL 48 IS 3 BP 1337 EP 1374 DI 10.1103/PhysRevD.48.1337 PG 38 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LP611 UT WOS:A1993LP61100039 ER PT J AU LEBOEUF, RL MEHTA, RD AF LEBOEUF, RL MEHTA, RD TI STREAMWISE VORTEX MEANDER IN A PLANE MIXING LAYER SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID FREE SHEAR-LAYER; VORTICAL STRUCTURES; EVOLUTION AB Previous measurements in a two-stream plane mixing layer have shown that the mean streamwise vorticity decays monotonically with downstream distance such that it is absent in the far-field (self-similar) region [J. H. Bell and R. D. Mehta, J. Fluid Mech. 239, 213 (1992); AIAA J. 28, 2034 (1990)]. It was not clear at that time if this measured decay reflected the diffusion of the instantaneous streamwise vorticity or was a result of increasing vortex meander within the mixing layer. The present experimental study was conducted in order to determine the existence of streamwise vortex meander in a mixing layer, and if present, its significance on the measured properties. The dependence of the velocity cross-correlation on the fixed probe location was shown to be a good indicator of the stationarity of the streamwise vortex location. The cross-correlation measurements obtained here indicate that spanwise meander is negligible, although transverse apparent meander (normal to the plane of the mixing layer) was indicated. The transverse meander, exemplified by the elliptical shape of the mean streamwise vorticity contours, was expected, since the streamwise vorticity in the braid region is essentially inclined, with respect to the streamwise direction. These conclusions were supported by results of estimated spanwise profiles of the transverse velocity component. The balance of evidence suggests that the measured mean streamwise vorticity decay is representative of the decay of the vorticity rather than an artifact of meander. C1 STANFORD UNIV, JIAA, DEPT AERONAUT & ASTRONAUT, STANFORD, CA 94305 USA. NASA, AMES RES CTR, FLUID MECH LAB, MOFFETT FIELD, CA 94035 USA. RP LEBOEUF, RL (reprint author), STANFORD UNIV, NASA AMES, CTR TURBULENCE RES, STANFORD, CA 94305 USA. NR 17 TC 8 Z9 8 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD AUG PY 1993 VL 5 IS 8 BP 1983 EP 1991 DI 10.1063/1.858825 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA LN702 UT WOS:A1993LN70200016 ER PT J AU JOHNSSON, A CHAPMAN, DK BROWN, A JOHNSONGLEBE, C KARLSSON, C HEATHCOTE, DG AF JOHNSSON, A CHAPMAN, DK BROWN, A JOHNSONGLEBE, C KARLSSON, C HEATHCOTE, DG TI GRAVITY SENSING IN OAT COLEOPTILES - SCATTER IN GROWTH ORIENTATION UNDER DIFFERENT G-CONDITIONS SO PLANT CELL AND ENVIRONMENT LA English DT Article DE GRAVITROPISM; CENTRIFUGE; SCATTER; RECIPROCITY; OAT; COLEOPTILE; GRAVITROPIC RESPONSE; HYPERGRAVITY AB Dark-grown oat seedlings depart from the expected vertical orientation, suggesting that the coleoptile is less responsive to the lateral component of a gravitational stimulus than would be expected. This phenomenon was studied by investigating the gravitropic curvatures of oat (A vena sativa L. cv. Seger) coleoptiles at 1.0 g and over a range of longitudinally applied centripetal accelerations up to 19.4 g. In most experiments, the plants were grown and observed at a particular g-level throughout the experiment. Time-lapse video recordings permitted studies of the scatter, measured as the variability of the plants' angle from the vertical (or root mean square value, RMS). The coleoptiles' heights at the end of the experiments were not significantly altered under the centrifugation. Scatter increased with plant age and decreased with increasing g. It decreased in an almost linear fashion as a function of the logarithm of the g-acceleration. In a series of experiments, the g-level was changed from 1.0 g to a higher test g-acceleration. The scatter was then reduced within half an hour after the g-transition. It is pointed out that the experiments confirm that the scatter is g-related but that it was not predicted quantitatively by present theories of the oat coleoptile's gravitropic response kinematics. C1 GRAVITAT PLANT PHYSIOL LAB,PHILADELPHIA,PA 19104. NASA,KENNEDY SPACE CTR,BIONET CORP,KENNEDY SPACE CTR,FL 32899. RP JOHNSSON, A (reprint author), UNIV TRONDHEIM,AVH,DEPT PHYS,N-7055 DRAGVOLL,NORWAY. NR 15 TC 3 Z9 3 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0140-7791 J9 PLANT CELL ENVIRON JI Plant Cell Environ. PD AUG PY 1993 VL 16 IS 6 BP 749 EP 754 DI 10.1111/j.1365-3040.1993.tb00495.x PG 6 WC Plant Sciences SC Plant Sciences GA LW930 UT WOS:A1993LW93000017 ER PT J AU LANDSMAN, W SIMON, T BERGERON, P AF LANDSMAN, W SIMON, T BERGERON, P TI THE HOT WHITE-DWARF COMPANIONS OF HR-1608, HR-8210, AND HD-15638 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID HUBBLE-SPACE-TELESCOPE; ULTRAVIOLET CALIBRATION; EVOLVED STARS; EMISSION; FLUXES; IUE AB We have obtained low-dispersion IUE spectra of the late-type stars HD 15638 (F3 V), HR 1608 (=63 Eridani, K0 IV), and HR 8210 (A8m). Each of these stars had been detected as a strong EUV source with the Wide Field Camera (WFC) aboard the ROSAT satellite. The short-wavelength IUE spectrum of each star reveals the presence of a hot white-dwarf companion. We have fit the Lyman alpha profile and ultraviolet continuum of each white dwarf using pure hydrogen models. The excellent fit of the data to the models provides confirmation of the Finley and Koester absolute calibration of the SWP camera of IUE. The ultraviolet data alone are insufficient to constrain the model gravity, but an additional constraint is provided by the photometric distance to the late-type primary. We derive T(eff)=50,000(-9500/+2000) K, log g=8.15(+0.15/-0.80) for the white-dwarf companion to HD 15638, T(eff)=26,000 +/- 1500 K, log g=7.5 +/- 0. 5 for the companion to HR 1608, and T(eff)=3 5,500 +/- 1500 K and log g=9.0(+0.15/-0.3) for the companion to HR 8210. The most interesting of the three white dwarfs is the companion to HR 8210 for which our results imply a mass of 1.15(+0.05/-0.15) M.. This result is in good agreement with the lower limit on the mass derived from the spectroscopic orbit (M> 1.1 M.), provided that the inclination is close to 90-degrees. HR 8210 thus shows similarities to the Sirius system, although with a cooler primary (7700 K vs 10,000 K), a hotter white dwarf (35,500 K vs 25,000 K), and a 100 times smaller component separation (3 X 10(7) km vs 3 X 10(9) km). We discuss the importance of future observations of HR 8210 for the study of high-mass white dwarfs, and for scenarios of binary-star evolution. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. UNIV MONTREAL,DEPT PHYS,MONTREAL H3C 3J7,QUEBEC,CANADA. RP LANDSMAN, W (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GSFC,HUGHES STX,CODE 681,GREENBELT,MD 20771, USA. NR 48 TC 36 Z9 37 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD AUG PY 1993 VL 105 IS 690 BP 841 EP 847 DI 10.1086/133242 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW251 UT WOS:A1993LW25100006 ER PT J AU COX, JC AF COX, JC TI TRADITIONAL ASIAN MARTIAL ARTS TRAINING - A REVIEW SO QUEST LA English DT Review ID KARATE; PERFORMANCE; PSYCHOLOGY; IMAGERY; SPORT AB Martial arts have become increasingly popular in the West, where they are practiced for self-defense, mental discipline, harmony of body and mind, physical fitness, and sport. It is estimated that 2-10 million Americans actively train. The literature pertaining to traditional martial arts training indicates that black belts do not conform to the violent, aggressive stereotypes portrayed in popular martial arts movies. Moreover, martial arts principles, philosophy, and techniques have been successfully applied in a clinical setting to improve the physical well-being of the physically challenged and to modify the attitudes, emotions, and behavior of troubled adults and teenagers. Mental imagery shows promise as a psychological intervention strategy to enhance Karate performance of beginning students. The techniques of Karate are well grounded in physics, and the velocities and tremendous forces and energies generated by skilled practitioners have been quantitated. Studies have also examined the health-related and skill-related fitness of martial artists. RP COX, JC (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SD4,BLDG 37,HOUSTON,TX 77058, USA. NR 78 TC 12 Z9 12 U1 3 U2 15 PU HUMAN KINETICS PUBL INC PI CHAMPAIGN PA 1607 N MARKET ST, CHAMPAIGN, IL 61820-2200 SN 0033-6297 J9 QUEST JI Quest PD AUG PY 1993 VL 45 IS 3 BP 366 EP 388 PG 23 WC Education & Educational Research; Sport Sciences SC Education & Educational Research; Sport Sciences GA LQ556 UT WOS:A1993LQ55600006 ER PT J AU KALMYKOV, AI VELICHKO, SA TSYMBAL, VN KULESHOV, YA WEINMAN, JA JURKEVICH, I AF KALMYKOV, AI VELICHKO, SA TSYMBAL, VN KULESHOV, YA WEINMAN, JA JURKEVICH, I TI OBSERVATIONS OF THE MARINE-ENVIRONMENT FROM SPACEBORNE SIDE-LOOKING REAL APERTURE RADARS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SENSOR MICROWAVE IMAGER; KOSMOS-1500 SATELLITE; SURFACE WINDS; SEA ICE; WAVES; OCEAN; PROGRAM AB Real aperture, side looking X-band radars have been operated from the Soviet Cosmos-1500, -1602, -1766 and Ocean satellites since 1984. These radar systems observe a 475 km wide swath with 1-2 km horizontal spatial resolution. Wind velocities were inferred from sea surface radar scattering for speeds ranging from approximately 2 m/s to those of hurricane proportions. The wind speeds were within 10-20% of the measured in situ values, and the direction of the wind velocity inferred from the radar measurements agreed with in situ direction measurements within 20-50-degrees. Various atmospheric mesoscale eddies and tropical cyclones were thus located, and their strengths were inferred from sea surface reflectivity measurements. Rain cells were observed over both land and sea with these spaceborne radars. Algorithms to retrieve rainfall rates from spaceborne radar measurements were also developed. Spaceborne radars have been used to monitor various marine hazards. For example, information derived from those radars was used to plan rescue operations of distressed ships trapped in sea ice. Icebergs have also been monitored. Because oil films reduce the sea surface roughness and thereby alter the radar reflectivity, oil spills were also mapped. Tsunamis produced by underwater earthquakes were also observed from space by the radars on the Cosmos-1500 series of satellites. The Cosmos-1500 satellite series have provided all weather radar imagery of the earth's surface to a user community in, real time by means of a 137.4 MHz Automatic Picture Transmission (APT) channel. This feature enabled the radar information to be used in direct support of Soviet polar maritime activities. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. USN, RES LAB, WASHINGTON, DC 20375 USA. RP UKRAINIAN ACAD SCI, INST RADIOPHYS & ELECTR, KHARKOV, UKRAINE. NR 54 TC 2 Z9 2 U1 0 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 EI 1879-0704 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 1993 VL 45 IS 2 BP 193 EP 208 DI 10.1016/0034-4257(93)90042-V PG 16 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA LM850 UT WOS:A1993LM85000007 ER PT J AU MCKNIGHT, D CHOBOTOV, V HERGOTT, R JOHNSON, NL LOFTUS, JP MEREDITH, PL PEREK, L REX, D SAX, H SUKHANOV, AA WOLFE, MG YASAKA, T AF MCKNIGHT, D CHOBOTOV, V HERGOTT, R JOHNSON, NL LOFTUS, JP MEREDITH, PL PEREK, L REX, D SAX, H SUKHANOV, AA WOLFE, MG YASAKA, T TI ORBITAL DEBRIS - STATUS AND POSSIBILITIES FOR CONTROL SO SPACE POLICY LA English DT Article AB This article is a shortened version of a position paper on orbital debris compiled by an Ad hoc Expert Group of the International Academy of Astronautics' Committee on Safety, Rescue and Quality. Its objectives were to elaborate on the need and urgency for action and to indicate ways for its implementation. The article reviews debris control options and methods ranging from those requiring no technology development to those which require new and thus far untried developments. C1 ESA, ESOC, DARMSTADT, GERMANY. AEROSP CORP, LOS ANGELES, CA 90009 USA. CNES, EVRY, FRANCE. KAMAN SCI CORP, COLORADO SPRINGS, CO USA. NASA, JSC, HOUSTON, TX 77058 USA. SPACE CONFORM, WASHINGTON, DC USA. CZECHOSLOVAK ACAD SCI, INST ASTRON, PRAGUE, CZECHOSLOVAKIA. TECH UNIV CAROLO WILHELMINA BRAUNSCHWEIG, W-3300 BRAUNSCHWEIG, GERMANY. DLR, COLOGNE, GERMANY. IKI, MOSCOW, RUSSIA. NIPPON TELEGRAPH & TEL PUBL CORP, YOKOSUKA, JAPAN. RP MCKNIGHT, D (reprint author), KAMAN SCI CORP, ALEXANDRIA, VA USA. NR 18 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0265-9646 EI 1879-338X J9 SPACE POLICY JI Space Policy PD AUG PY 1993 VL 9 IS 3 BP 185 EP 198 PG 14 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA LT055 UT WOS:A1993LT05500002 ER PT J AU MIRANDA, FA AF MIRANDA, FA TI MICROWAVE PROPERTIES OF TL-BA-CA-CU-O THIN-FILMS SO SUPERCONDUCTOR SCIENCE & TECHNOLOGY LA English DT Article ID RESONATOR TECHNIQUE; PENETRATION DEPTH; YBA2CU3O7-DELTA; CONDUCTIVITY; TC; TEMPERATURE; SUPERCONDUCTORS; TRANSMISSION; PERFORMANCE; FILTERS AB A study of the microwave properties of Tl-Ba-Ca-Cu-O (TBCCO) thin films deposited on LaAlO3 has been performed. These films have transition temperatures (T(c, R=0)) within 101-105 K, and were predominantly c-axis oriented with critical current densities (J(c)) of approximately 1.6 x 10(5) and 2.8 x 10(6) A cm-2 at zero field and at 77 and 4.5 K respectively. By using a power transmission method we have determined the complex conductivity (sigma* = sigam1 - jsigma2) and the magnetic penetration depth (lambda) at 33.5 GHz. To the best of our knowledge this represents the first report published on sigma* for TBCCO films. It was observed that in the superconducting state sigma1 deviates from the predictions of the Bardeen-Cooper-Schrieffer (BCS) theory and the phenomenological two-fluid model. Values of lambda of 613 and 555 nm were obtained at 77 and 20 K respectively. The surface resistance (R(s)) of these films was determined after patterning them into a conductor-backed coplanar waveguide (CBCPW) resonators, ring resonators, and microstrip linear resonators, by measuring the quality factor (Q) at cryogenic temperatures. At 77 K and 10.8 GHz, the best of our CBCPW resonators has an unloaded quality factor (Q0) seven times that of a similar all-gold resonator. For neighbouring ring and linear resonators fabricated on the same high transition temperature superconductor film, Q0 was found to be approximately three times that of a similar gold resonator at 77 K and 8 GHz. R(s) values at 77 K of 6.6 and 4.5 mOMEGA were obtained at 10.8 and 8 GHz respectively. RP MIRANDA, FA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 39 TC 14 Z9 14 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-2048 J9 SUPERCOND SCI TECH JI Supercond. Sci. Technol. PD AUG PY 1993 VL 6 IS 8 BP 605 EP 613 DI 10.1088/0953-2048/6/8/009 PG 9 WC Physics, Applied; Physics, Condensed Matter SC Physics GA LV906 UT WOS:A1993LV90600009 ER PT J AU CAMPBELL, MR BILLICA, RD JOHNSTON, SL AF CAMPBELL, MR BILLICA, RD JOHNSTON, SL TI SURGICAL BLEEDING IN MICROGRAVITY SO SURGERY GYNECOLOGY & OBSTETRICS LA English DT Article ID STATION AB A surgical procedure performed during space flight would occur in a unique microgravity environment. Several experiments performed during weightlessness in parabolic flight were reviewed to ascertain the behavior of surgical bleeding in microgravity. Simulations of bleeding using dyed fluid and citrated bovine blood, as well as actual arterial and venous bleeding in rabbits, were examined. The high surface tension property of blood promotes the formation of large fluid domes, which have a tendency to adhere to the wound. The use of sponges and suction will be adequate to prevent cabin atmosphere contamination with all bleeding, with the exception of temporary arterial droplet streams. The control of the bleeding with standard surgical techniques should not be difficult. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 19 TC 22 Z9 22 U1 0 U2 0 PU FRANKLIN H MARTIN FOUNDATION PI CHICAGO PA 55 E ERIE ST, CHICAGO, IL 60611 SN 0039-6087 J9 SURG GYNECOL OBSTET JI Surg. Gynecol. Obstet. PD AUG PY 1993 VL 177 IS 2 BP 121 EP 125 PG 5 WC Obstetrics & Gynecology; Surgery SC Obstetrics & Gynecology; Surgery GA LQ640 UT WOS:A1993LQ64000002 PM 8342090 ER PT J AU RAO, MVVS SRIVASTAVA, SK AF RAO, MVVS SRIVASTAVA, SK TI ELECTRON-IMPACT IONIZATION AND ATTACHMENT CROSS-SECTIONS FOR H2S SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID DISSOCIATIVE ATTACHMENT; HDS; D2S AB First measurements of the absolute values of cross sections for ionization and dissociative ionization of H2S by electron impact for the energy range of 0 to 1000 eV are reported. Cross sections for the formation of negative ions (HS- and S-) resulting from the electron attachment to H2S have also been obtained and are compared with previous measurements. C1 JET PROP LAB,PASADENA,CA 91109. NR 28 TC 27 Z9 27 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUL 25 PY 1993 VL 98 IS E7 BP 13137 EP 13145 DI 10.1029/92JE02318 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LP808 UT WOS:A1993LP80800005 ER PT J AU REINER, MJ FAINBERG, J STONE, RG KAISER, ML DESCH, MD MANNING, R ZARKA, P PEDERSEN, BM AF REINER, MJ FAINBERG, J STONE, RG KAISER, ML DESCH, MD MANNING, R ZARKA, P PEDERSEN, BM TI SOURCE CHARACTERISTICS OF JOVIAN NARROW-BAND KILOMETRIC RADIO EMISSIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ULYSSES RADIO; PLASMA TORUS; RADIATION; JUPITER; ROTATION; PLANETS AB New observations of Jovian narrow-band kilometric (nKOM) radio emissions were made by the Unified Radio and Plasma Wave (URAP) experiment on the Ulysses spacecraft during the Ulysses-Jupiter encounter in early February 1992. These observations have demonstrated the unique capability of the URAP instrument for determining both the direction and polarization of nKOM radio sources. An important result is the discovery that nKOM radio emission originates from a number of distinct sources located at different Jovian longitudes and at the inner and outermost regions of the lo plasma torus. These sources have been tracked for several Jovian rotations, yielding their corotational lags, their spatial and temporal evolution, and their radiation characteristics at both low latitudes far from Jupiter and at high latitudes near the planet, Both right-hand and left-hand circularly polarized nKOM sources were observed. The polarizations observed for sources in the outermost regions of the torus seem to favor extraordinary mode emission. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. OBSERV PARIS,F-92190 MEUDON,FRANCE. RP REINER, MJ (reprint author), HUGHES STX,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 24 TC 36 Z9 36 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUL 25 PY 1993 VL 98 IS E7 BP 13163 EP 13176 DI 10.1029/93JE00536 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LP808 UT WOS:A1993LP80800007 ER PT J AU MOTE, PW HOLTON, JR RUSSELL, JM BOVILLE, BA AF MOTE, PW HOLTON, JR RUSSELL, JM BOVILLE, BA TI A COMPARISON OF OBSERVED (HALOE) AND MODELED (CCM2) METHANE AND STRATOSPHERIC WATER-VAPOR SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LATE WINTER; VORTEX AB Recent measurements (21 September - 15 October 1992) of methane and water vapor by the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) are compared with model results for the same season from a troposphere-middle atmosphere version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2). Several important features of the two constituent fields are well reproduced by the CCM2, despite the use of simplified methane photochemistry in the CCM2 and some notable differences between the model's zonal mean circulation and climatology. Observed features simulated by the model include the following: 1) subsidence over a deep layer in the Southern Hemisphere polar vortex; 2) widespread dehydration in the polar vortex; 3) existence of a region of low water vapor mixing ratios extending from the Antarctic into the Northern Hemisphere tropics, which suggests that Antarctic dehydration contributes to midlatitude and tropical dryness in the stratosphere. C1 NATL CTR ATMOSPHER RES,BOULDER,CO 80307. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP MOTE, PW (reprint author), UNIV WASHINGTON,DEPT ATMOSPHER SCI AK40,SEATTLE,WA 98195, USA. NR 19 TC 17 Z9 17 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 23 PY 1993 VL 20 IS 14 BP 1419 EP 1422 DI 10.1029/93GL01764 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LQ439 UT WOS:A1993LQ43900003 ER PT J AU MLYNCZAK, MG AF MLYNCZAK, MG TI AN EVALUATION OF THE RATE OF ABSORPTION OF SOLAR-RADIATION IN THE O2(X3-SIGMA-G-]B1-SIGMA-G) TRANSITION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The rate at which molecular oxygen absorbs radiation in the O2(X3SIGMA(g)-->b1SIGMA(g)) transition is calculated using a line-by-line radiative transfer model. This rate is critical to the determination of the population of the O2(b1SIGMA(g)) state required for studies of the O2(b1SIGMA(g)-->X3SIGMA(g)) dayglow, the O2(a1DELTA(g)-->X3SIGMA(g)) dayglow, and possibly the rates of oxidation of H-2 and N2O. Previous evaluations of this rate (which is sometimes called the g-factor) have significantly overestimated its value. The rate is tabulated as a function of altitude, pressure, and solar zenith angle. RP MLYNCZAK, MG (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 401B,HAMPTON,VA 23681, USA. RI Mlynczak, Martin/K-3396-2012 NR 10 TC 16 Z9 16 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 23 PY 1993 VL 20 IS 14 BP 1439 EP 1442 DI 10.1029/93GL01457 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LQ439 UT WOS:A1993LQ43900008 ER PT J AU HESSE, M BIRN, J AF HESSE, M BIRN, J TI ON THE ENERGY BUDGET IN THE CURRENT DISRUPTION REGION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PLASMA SHEET; MAGNETOTAIL; TAIL AB This study investigates the energy budget in the current disruption region of the magnetotail, coincident with a pre-onset thin current sheet, around substorm onset time using published observational data and theoretical estimates. We find that the current disruption/dipolarization process typically requires energy inflow into the primary disruption region. The disruption dipolarization process is therefore endoenergetic, i.e., requires energy input to operate. Therefore we argue that some other simultaneously operating process, possibly a large scale magnetotail instability, is required to provide the necessary energy input into the current disruption region. C1 LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. RP NASA, GODDARD SPACE FLIGHT CTR, ELECTRODYNAM BRANCH, CODE 696, GREENBELT, MD 20771 USA. RI Hesse, Michael/D-2031-2012 NR 16 TC 19 Z9 19 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 23 PY 1993 VL 20 IS 14 BP 1451 EP 1454 DI 10.1029/93GL01587 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LQ439 UT WOS:A1993LQ43900011 ER PT J AU SCHWENKE, DW AF SCHWENKE, DW TI COMPARISON OF CROSS-SECTIONS FROM THE QUASI-CLASSICAL TRAJECTORY METHOD AND THE JZ-CONSERVING CENTRIFUGAL SUDDEN APPROXIMATION WITH ACCURATE QUANTUM RESULTS FOR AN ATOM-RIGID NONLINEAR POLYATOMIC COLLISION SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID POTENTIAL-ENERGY SURFACE; SYMMETRIC TOP MOLECULES; ROTATIONAL EXCITATION; COUPLED STATES; INTERSTELLAR TEMPERATURES; VARIATIONAL CALCULATION; REACTIVE SCATTERING; ASYMMETRIC-TOP; H2O; RECOMBINATION AB We report the results of a series of calculations of state-to-state integral cross sections for collisions between O and nonvibrating H2O in the gas phase on a model nonreactive potential energy surface. The dynamical methods used in the present study include converged quantum mechanical scattering calculations, the j(z) conserving centrifugal sudden (j(z)-CCS) approximation, and quasi-classical trajectory (QCT) calculations. We consider three total energies 0.001, 0.002, and 0.005 E(h) and the nine initial states with rotational angular momentum less than or equal to 2hBAR. The j(z)-CCS approximation gives good results, while the QCT method can be quite unreliable for transitions to specific rotational sublevels. However the QCT cross sections summed over final sublevels and averaged over initial sublevels are in better agreement with the quantum results. RP SCHWENKE, DW (reprint author), NASA,AMES RES CTR,MS 230-3,MOFFETT FIELD,CA 94035, USA. RI schwenke, david/I-3564-2013 NR 42 TC 3 Z9 3 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUL 22 PY 1993 VL 97 IS 29 BP 7627 EP 7638 DI 10.1021/j100131a036 PG 12 WC Chemistry, Physical SC Chemistry GA LW329 UT WOS:A1993LW32900036 ER PT J AU CHU, LT LEU, MT KEYSER, LF AF CHU, LT LEU, MT KEYSER, LF TI UPTAKE OF HCL IN WATER ICE AND NITRIC-ACID ICE FILMS SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID ANTARCTIC OZONE DEPLETION; POLAR STRATOSPHERIC CLOUDS; HETEROGENEOUS REACTIONS; HYDROGEN-CHLORIDE; HYDROCHLORIC-ACID; INFRARED-SPECTRA; VAPOR-PRESSURES; TRIHYDRATE; N2O5; NITRATE AB The uptake of HCl in water ice and nitric acid ice films has been investigated in a flow reactor interfaced with a differentially pumped quadrupole mass spectrometer. These studies were performed under experimental conditions that may mimic the polar stratosphere. The HCl uptake in ice films at 188 and 193 K was determined to be in the range of 8.7 X 10(13) to 1.8 X 10(15) molecules/cm2 (if the geometric area of the flow reactor, 290 cm2, was used in the calculation) when HCl partial pressures of 7 X 10(-8) to 6 X 10(-6) Torr were used. On the basis of a model which accounts for the total surface area of the films, the true surface density could be a factor of 25 lower than that calculated by the geometric area. A slightly higher uptake was observed at the lower temperature of 188 K. The uptake of HCl in ice was significantly enhanced by using an HCl partial pressure greater than 1 X 10(-5) Torr. The observation was found to be consistent with the formation of the hexahydrate or the trihydrate of HCl according to the phase diagram of the HCl/H2O system. The uptake of HCl in nitric acid ice at 188 K was determined to be in the range of 8.0 X 10(13) to 5.3 X 10(14) molecules/cm2 at a HCl partial pressure of 4.5 X 10(-7) Torr. Measurement of both HNO3 and H2O vapor pressures was made to positively identify the formation of nitric acid trihydrate (NAT) surface according to the phase diagram of the HNO3/H2O system. The HCl uptake in NAT is comparable to that in water ice in the present experiment, but significantly smaller than the previously reported values by Mauersberger and his co-workers. Implications of these results for the heterogeneous chemistry of the polar ozone depletion are briefly discussed. C1 JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. NR 40 TC 112 Z9 112 U1 0 U2 10 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUL 22 PY 1993 VL 97 IS 29 BP 7779 EP 7785 DI 10.1021/j100131a057 PG 7 WC Chemistry, Physical SC Chemistry GA LW329 UT WOS:A1993LW32900057 ER PT J AU ANSARI, RR DHADWAL, HS CHEUNG, HM MEYER, WV AF ANSARI, RR DHADWAL, HS CHEUNG, HM MEYER, WV TI MICROEMULSION CHARACTERIZATION BY THE USE OF A NONINVASIVE BACKSCATTER FIBER OPTIC PROBE SO APPLIED OPTICS LA English DT Article DE DYNAMIC LIGHT SCATTERING; FIBER OPTIC SENSORS; PARTICLE SIZING; MICROEMULSIONS; FUELS; QUASI-ELASTIC LIGHT SCATTERING ID 3-PHASE MICELLAR SYSTEMS; DOPPLER ANEMOMETER; LIGHT-SCATTERING; MIDDLE PHASE; CONCENTRATED DISPERSIONS; SEDIMENTATION; PARTICLES; MOTILITY; SIZE; FODA AB This paper demonstrates the utility of a noninvasive backscatter fiber optic probe for dynamic light-scattering characterization of a microemulsion comprising sodium dodecyl sulfate/1-butanol/brine/heptane. The fiber probe, comprising two optical fibers precisely positioned in a stainless steel body, is a miniaturized and efficient self-beating dynamic light-scattering system. Accuracy of particle size estimation is better than +/- 2%. C1 SUNY, DEPT ELECT ENGN, STONY BROOK, NY 11794 USA. UNIV AKRON, DEPT CHEM ENGN, AKRON, OH 44325 USA. RP ANSARI, RR (reprint author), CASE WESTERN RES UNIV, NASA, LEWIS RES CTR, MAIL STOP 105-1, 21000 BROOKPARK RD, CLEVELAND, OH 44135 USA. NR 29 TC 9 Z9 9 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1993 VL 32 IS 21 BP 3822 EP 3827 PG 6 WC Optics SC Optics GA LN837 UT WOS:A1993LN83700003 PM 20830012 ER PT J AU TURNER, TJ GEORGE, IM MUSHOTZKY, RF AF TURNER, TJ GEORGE, IM MUSHOTZKY, RF TI ROSAT POSITION-SENSITIVE PROPORTIONAL COUNTER SPECTRA OF 6 SEYFERT-1 GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, SEYFERT; X-RAYS, GALAXIES ID X-RAY SPECTRA; ACTIVE GALACTIC NUCLEI; EXOSAT OBSERVATIONS; COLD MATTER; EXCESS; EMISSION; VARIABILITY; QUASARS; CONSTRAINTS; REFLECTION AB We present the results from ROSAT Position Sensitive Proportional Counter (PSPC) observations of six Seyfert 1 galaxies in the soft (0.1-2.0 keV) X-ray band. The sources (Mrk 335, ESO 198-G24, ESO 141-G55, Mrk 509, NGC 7469, and MCG-2-58-22) were chosen to have low absorbing column densities (N(H) approximately 10(20) cm-2) along the line of sight. As expected, it is found that all the sources possess significantly steeper spectra below approximately 1 keV than observed at higher X-ray energies. Assuming a simple absorbed power-law spectral model, the mean (photon) spectral index for the sample is GAMMA = 2.38 +/- 0.25, compared to the canonical GAMMA approximately 1.7 typically observed in the 2-10 keV band. Furthermore, we find strong evidence for soft X-ray spectral features in half the sources. In NGC 7469 and ESO 198-G24, we find that the addition of a narrow emission line or an absorption edge to the underlying continuum is a significant improvement to the parameterization of the spectra. Mrk 335 also shows evidence for spectral complexity, but from these data it is not possible to unambiguously distinguish between an absorption edge and a steepening of the spectrum at low energies. We examine these results in the light of the accuracy of the PSPC spectral calibration. We discuss the implications of these results on physical models for the X-ray emission of Seyfert 1 galaxies as a whole. In particular, we suggest that Seyfert 1 galaxies may make a major contribution to the soft X-ray background. Since these sources make only a minor contribution to the hard X-ray (2-40 keV) background, these data therefore provide evidence that the sources which dominate the background differ as a function of energy. RP TURNER, TJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,POSTAL CODE 668,GREENBELT,MD 20771, USA. NR 57 TC 65 Z9 65 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1993 VL 412 IS 1 BP 72 EP 81 DI 10.1086/172901 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LM214 UT WOS:A1993LM21400006 ER PT J AU REACH, WT HEILES, C KOO, BC AF REACH, WT HEILES, C KOO, BC TI THE NATURE OF UNIDENTIFIED FAR-INFRARED POINT SOURCES SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; INFRARED, GALAXIES; INFRARED, INTERSTELLAR, CONTINUUM; ISM, MOLECULES ID MOLECULAR CLOUDS; H-I; IRAS OBSERVATIONS; ZETA-OPHIUCHI; RADIO-SOURCES; DRACO NEBULA; GALAXIES; CIRRUS; RATIO; DUST AB Sources discovered by the Infrared Astronomical Satellite with spectra that rise steeply from 60 to 100 mum are a mixed sample of external galaxies, condensations in the interstellar medium, and potentially unknown astronomical objects. Sources in regions of low total H I column density (as determined with the all-sky 21 cm line surveys), and with no nearby cataloged external galaxy, were observed for presence of 20 cm continuum emission (with the NRAO Very Large Array), enhanced 21 cm H I line emission (with the NAIC Arecibo 305 m), and molecular line emission (with the NRAO 12 m, HCRO 6 m, and FCRAO 14 m). Based on the CO detection rate, 70% of our sample are small interstellar molecular clouds. The remainder are mostly faint external galaxies. The dust column densities of the interstellar condensations were determined from the infra-red flux, using a spherical-cloud model for the radiative transfer of the interstellar radiation field (ISRF). The CO column densities were determined using the large-velocity-gradient model for the excitation and radiative transfer of the rotational transitions. About half of the interstellar sources have normal dust-to-gas ratios and ISRF heating. Sources with excess infrared emission, compared to the molecular column density, are protostellar candidates. Sources in the Draco nebula are rich in CO but deficient in dust. The remaining interstellar sources, which have pressure some two orders of magnitude higher than the average interstellar pressure, may be accretion nebulae around stellar remnants. C1 SEOUL NATL UNIV,DEPT ASTRON,SEOUL 151742,SOUTH KOREA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP REACH, WT (reprint author), UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720, USA. OI Reach, William/0000-0001-8362-4094 NR 58 TC 15 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1993 VL 412 IS 1 BP 127 EP 145 DI 10.1086/172906 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LM214 UT WOS:A1993LM21400011 ER PT J AU STOTHERS, RB CHIN, CW AF STOTHERS, RB CHIN, CW TI IRON AND MOLECULAR OPACITIES AND THE EVOLUTION OF POPULATION-I STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ABUNDANCES; STARS, EVOLUTION; STARS, INTERIORS; SUPERGIANTS ID ELEMENTAL ABUNDANCE ANALYSES; MAIN-SEQUENCE; SOLAR; HERCULIS; SYSTEM; SPECTROGRAMS; NGC-1866; MODELS AB Effects of recent opacity revisions on the evolution of Population I stars are explored over the mass range 1.5-60 M.. Opacities are due to Iglesias, Rogers, and Wilson (high temperatures) and to Sharp and to Alexander, Johnson, and Rypma (low temperatures). Opacity parameters considered include the angular momentum coupling scheme for iron, the relative iron abundance, the total metal abundance, and diatomic and triatomic molecular sources. Surprisingly, only the total metal abundance exerts an important control over the evolutionary tracks. Blue loops on the H-R diagram during core helium burning can be very sensitive to opacity, but only insofar as the simple formation or suppression of a blue loop is concerned. The blue loops are most robust for stellar masses around 10 ME.. We confirm, from a comparison of stellar models with observational data, that the total metal abundance is close to solar and that convective core overshooting is likely to be very slight. The new models predict the existence of an iron convection zone in the envelope and a great widening of the main-sequence band in the H-R diagram at luminosities brighter than 10(5) L.. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 50 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1993 VL 412 IS 1 BP 294 EP 300 DI 10.1086/172920 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LM214 UT WOS:A1993LM21400025 ER PT J AU MILLER, JA VINAS, AF AF MILLER, JA VINAS, AF TI ION-ACCELERATION AND ABUNDANCE ENHANCEMENTS BY ELECTRON-BEAM INSTABILITIES IN IMPULSIVE SOLAR-FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; PLASMAS; SUN, ABUNDANCES; SUN, CORONA; SUN, FLARES; SUN, PARTICLE EMISSIONS ID TEST PARTICLE-ACCELERATION; ELECTROMAGNETIC-WAVES; HE-3-RICH EVENTS; MAGNETIC-FIELD; HEAVY-IONS; PRECIPITATION; PROPAGATION; EQUILIBRIUM; EXCITATION; EVOLUTION AB We show that a nonrelativistic electron beam in a hydrogen-helium solar flare plasma will excite H+ electromagnetic ion cyclotron, shear Alfven, and R-X waves, in addition to waves resulting from the two-stream instability. The H+ electromagnetic ion cyclotron and shear Alfven waves are able to selectively accelerate ambient He-3 and Fe, respectively, to MeV energies through first harmonic gyroresonance, and thereby account for the large He-3/He-4 and Fe/C ratios seen in the energetic particles from impulsive solar flares. In this model, separate heating and acceleration mechanisms for either He-3 or Fe are not required, and Fe acceleration is quite efficient since it does not need to occur by second harmonic gyroresonance. The combination of the other two unstable modes is able to accelerate ions to hundreds of MeV if the particles become trapped in an electrostatic potential well of a two-stream wave. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP MILLER, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 665,GREENBELT,MD 20771, USA. NR 79 TC 113 Z9 114 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1993 VL 412 IS 1 BP 386 EP 400 DI 10.1086/172928 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LM214 UT WOS:A1993LM21400033 ER PT J AU GREEN, S AF GREEN, S TI COLLISIONAL EXCITATION OF CO BY H2O - AN ASTROPHYSICISTS GUIDE TO OBTAINING RATE CONSTANTS FROM COHERENT ANTI-STOKES-RAMAN LINE-SHAPE DATA SO ASTROPHYSICAL JOURNAL LA English DT Article DE LINE PROFILES; MOLECULAR PROCESSES ID ROTATIONAL ENERGY-TRANSFER; TEMPERATURE-RANGE; SPECTRA; WIDTHS; N-2; N2; O2 AB Rate constants for excitation of CO by collisions with H2O are needed to understand recent observations of comet spectra. These collision rates are closely related to spectral line shape parameters, especially those for Raman Q-branch spectra. Because such spectra have become quite important for thermometry applications, much effort has been invested in understanding this process. Although it is not generally possible to extract state-to-state rate constants directly from the data as there are too many unknowns, if the matrix of state-to-state rates can be expressed in terms of a rate-law model which depends only on rotational quantum numbers plus a few parameters, the parameters can be determined from the data; this has been done with some success for many systems, especially those relevant to combustion processes. Although such an analysis has not yet been done for CO-H2O, the system is expected to behave similarly to N2-H2O which has been well studied; modifications of parameters for the latter system are suggested which should provide a reasonable description of rate constants for the former. RP GREEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 20 TC 10 Z9 10 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1993 VL 412 IS 1 BP 436 EP 440 DI 10.1086/172933 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LM214 UT WOS:A1993LM21400038 ER PT J AU BOUGHN, SP JAHODA, K AF BOUGHN, SP JAHODA, K TI A COMPARISON OF THE COSMIC MICROWAVE AND COSMIC X-RAY BACKGROUNDS - CONSTRAINTS ON LOCAL-SOURCES OF THE FLUCTUATIONS OBSERVED BY COBE SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS; INTERGALACTIC MEDIUM; X-RAYS, GENERAL AB It has been suggested by Hogan (1992) that the microwave background anisotropy detected by the COBE DMR experiment (Smoot et al. 1992) might be produced by inverse Compton scattering from hot diffuse clouds of electrons in nearby superclusters. If the COBE fluctuations are due to this mechanism, then the absence of anticorrelations between maps of the cosmic microwave and cosmic X-ray backgrounds constrains the temperature (kT(e) > 16 keV) and density (n(e) < 2 x 10(-6) cm-3) of the ionized supercluster gas. Since the COBE limits on spectral distortion indicate that the temperature of the intergalactic medium is less than 10 keV, we conclude that the fluctuations observed by COBE are probably not produced by this mechanism. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BOUGHN, SP (reprint author), HAVERFORD COLL,DEPT ASTRON,HAVERFORD,PA 19041, USA. RI Jahoda, Keith/D-5616-2012 NR 14 TC 15 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1993 VL 412 IS 1 BP L1 EP L4 DI 10.1086/186925 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LM215 UT WOS:A1993LM21500001 ER PT J AU SCHLEGEL, EM PETRE, R AF SCHLEGEL, EM PETRE, R TI A ROSAT UPPER LIMIT ON X-RAY-EMISSION FROM SN-1992A SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUPERNOVAE, INDIVIDUAL, SN-1992A; X-RAYS, STARS ID RADIO-EMISSION; I SUPERNOVA; LIGHT; 1987A AB We have used the Position Sensitive Proportional Counter (PSPC) on ROSAT to search for X-ray emission from the Type Ia supernova 1992A in NGC 1380 approximately 16 days after the outburst maximum. No X-ray emission is present to a flux of approximately 4 x 10(-14) ergs s-1 cm-2, which corresponds-to a 0.5-2 keV luminosity 99% upper limit of approximately 3-5 x 10(38) ergs s-1. This implies a presupernova mass-loss rate of less than a few x 10(-6) M. yr-1. This is the most sensitive upper limit, by several orders of magnitude, yet obtained for a Type Ia supernova. C1 UNIV SPACE RES ASSOC,COLUMBIA,MD 21044. RP SCHLEGEL, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 36 TC 25 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1993 VL 412 IS 1 BP L29 EP L32 DI 10.1086/186932 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LM215 UT WOS:A1993LM21500008 ER PT J AU WHARTON, RA LYONS, WB MARAIS, DJD AF WHARTON, RA LYONS, WB MARAIS, DJD TI STABLE ISOTOPIC BIOGEOCHEMISTRY OF CARBON AND NITROGEN IN A PERENNIALLY ICE-COVERED ANTARCTIC LAKE SO CHEMICAL GEOLOGY LA English DT Article ID ORGANIC-CARBON; ALGAL MATS; SEDIMENTS; DELTA-C-13; OXYGEN; WATER; SUPERSATURATION; REGENERATION; ABUNDANCE; FRYXELL AB Lake Hoare (77-degrees-38'S, 162-degrees-53'E) is an amictic, oligotrophic, 34-m-deep, closed-basin lake in Taylor Valley, Antarctica. Its perennial ice cover minimizes wind-generated currents and reduces light penetration, as well as restricts sediment deposition into the lake and the exchange of atmospheric gases between the water column and the atmosphere. The biological community of Lake Hoare consists solely of microorganisms - both planktonic populations and benthic microbial mats. Lake Hoare is one of several perennially ice-covered lakes in the McMurdo Dry Valleys that represent the end-member conditions of cold desert and saline lakes. The dry valley lakes provide a unique opportunity to examine lacustrine processes that operate at all latitudes, but under an extreme set of environmental conditions. The dry valley lakes may also offer a valuable record of catchment and global changes in the past and present. Furthermore. these lakes are modern-day equivalents of periglacial lakes that are likely to have been common during periods of glacial maxima at temperate latitudes. We have analyzed the dissolved inorganic carbon (DIC) of Lake Hoare for deltaC-13 and the organic matter of the sediments and sediment-trap material for deltaC-13 and deltaN-15. The deltaC-13 of the DIC indicates that C-12 is differentially removed in the shallow, oxic portions of the lake via photosynthesis. In the anoxic portions of the lake (27-34 m) a net addition of C-12 to the DIC pool occurs via organic matter decomposition. The dissolution of CaCO3 at depth also contributes to the DIC pool. Except near the Canada Glacier where a substantial amount of allochthonous organic matter enters the lake, the organic carbon being deposited on the lake bottom at different sites is isotopically similar, suggesting an autochthonous source for the organic carbon. Preliminary inorganic carbon flux calculations suggest that a high percentage of the organic carbon fixed in the water column is remineralized as it falls through the water column. At nearby Lake Fryxell, the substantial (relative to Lake Hoare) glacial meltstream input overprints Fryxell's shallow-water biological deltaC-13 signal with deltaC-13-depleted DIC. In contrast, Lake Hoare is not significantly affected by surface-water input and mixing, and therefore the deltaC-13 patterns observed arise primarily from biological dynamics within the lake. Organic matter in Lake Hoare is depleted in N-15, which we suggest is partially the result of the addition of relatively light inorganic nitrogen into the lake system from terrestrial sources. C1 UNIV NEVADA,HYDROL HYDROGEOL PROGRAM,RENO,NV 89557. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP WHARTON, RA (reprint author), UNIV NEVADA,DESERT RES INST,RENO,NV 89506, USA. NR 57 TC 25 Z9 25 U1 1 U2 16 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2541 J9 CHEM GEOL JI Chem. Geol. PD JUL 20 PY 1993 VL 107 IS 1-2 BP 159 EP 172 DI 10.1016/0009-2541(93)90108-U PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LP588 UT WOS:A1993LP58800011 PM 11539299 ER PT J AU MCDONALD, KC ULABY, FT AF MCDONALD, KC ULABY, FT TI RADIATIVE-TRANSFER MODELING OF DISCONTINUOUS TREE CANOPIES AT MICROWAVE-FREQUENCIES SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID WALNUT ORCHARD; SCATTER MODEL; VEGETATION; BACKSCATTER; BAND; LAYER AB Development of a first-order radiative transfer model for predicting backscatter from tree canopies has been underway at the University of Michigan Radiation Laboratory for some time. This model is known as the Michigan Microwave Canopy Scattering (MIMICS) model. The first-generation model, MIMICS I, was developed for canopies with continuous (closed) crown layers and its validity has been verified in several modelling analyses. This article presents the second-generation MIMICS model (MIMICS II) which accounts for canopies with discontinuous (open) crown layer geometries. MIMICS II models open crown layers by treating the location, size and shape of the individual tree crowns as random variables. The backscattering coefficients for the canopy are then determined by introducing statistics derived from these parameters into the radiative transfer solution. Application of the radiative transfer equations to the discontinuous canopy geometry is presented. The application of random variables defining the crown geometry and the incorporation of these variables into the radiative transfer solution is discussed. The resulting model is a robust fully polarimetric solution that is applicable over a wide variety of canopy architectures. Model simulations are compared to results generated with the continuous canopy model. The effect of the open crown geometry is found to be most significant at shallow incidence angles and at high frequencies for trees with well-developed crowns. Under these conditions, the gaps in the crown layer give rise to a notable increase in crown layer transmissivity which allows the radar to see through to the lower layers of the canopy more easily thereby directly affecting the backscatter contribution of the trunks and ground. C1 UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,RADIAT LAB,ANN ARBOR,MI 48109. RP MCDONALD, KC (reprint author), JET PROP LAB,MAIL STOP 300-233,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 28 TC 33 Z9 35 U1 1 U2 8 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 20 PY 1993 VL 14 IS 11 BP 2097 EP 2128 PG 32 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA LT092 UT WOS:A1993LT09200004 ER PT J AU HOLBEN, BN SHIMABUKURO, YE AF HOLBEN, BN SHIMABUKURO, YE TI LINEAR MIXING MODEL APPLIED TO COARSE SPATIAL-RESOLUTION DATA FROM MULTISPECTRAL SATELLITE SENSORS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Letter ID AVHRR DATA; FOREST COVER; SOIL AB A linear mixing model was applied to coarse spatial resolution data from the NOAA Advanced Very High Resolution Radiometer. The reflective component of the 3.55-3.95 mum channel was used with the two reflective channels 0.58-0.68 mum and 0.725-1.1 mum to run a Constrained Least Squares model to generate fraction images for an area in the west central region of Brazil. The fraction images were compared with an unsupervised classification derived from Landsat TM data acquired on the same day. In addition, the relationship between the fraction images and normalized difference vegetation index images show the potential of the unmixing techniques when using coarse spatial resolution data for global studies. C1 INST NACL PESQUISAS ESPACIAIS,S JOSE CAMPO,SP,BRAZIL. RP HOLBEN, BN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 923,GREENBELT,MD 20771, USA. NR 22 TC 58 Z9 61 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 20 PY 1993 VL 14 IS 11 BP 2231 EP 2240 PG 10 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA LT092 UT WOS:A1993LT09200012 ER PT J AU HERMAN, JR MCPETERS, R LARKO, D AF HERMAN, JR MCPETERS, R LARKO, D TI OZONE DEPLETION AT NORTHERN AND SOUTHERN LATITUDES DERIVED FROM JANUARY 1979 TO DECEMBER 1991 TOTAL OZONE MAPPING SPECTROMETER DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC TEMPERATURES; EL-CHICHON; TOMS DATA; SAM-II; TRENDS; PINATUBO; ERUPTION; DENITRIFICATION; HEMISPHERE; ANTARCTICA AB Long-term ozone depletion rates (percentage change) have been computed from 13 years of Nimbus 7/Total Ozone Mapping Spectrometer (TOMS) data as a function of latitude, longitude, and month for the period January 1, 1979, to December 31, 1991. In both hemispheres the amount of ozone has decreased at latitudes above 30-degrees by amounts that are larger than predicted by homogeneous chemistry models for the 13-year time period. The largest rates of ozone decrease occur in the southern hemisphere during winter and spring, with partial recovery during the summer and autumn. Outside of the Antarctic ozone hole region, the 12-year ozone depletion rates reach 8-10% per decade during the winter and spring at 55-degrees-S. Ozone depletion rates in excess of 7% per decade occur over populated regions in the southern hemisphere poleward of 45-degrees-S (southern Argentina and the tip of New Zealand) for 7 months of the year. Similar rates of decrease occur during northern winter and spring (6-8% at 55-degrees-N) over large populated regions. The enhanced zonal average ozone depletion rates at northern mid-latitudes (40-50-degrees-N) during January, February, and March, that correspond to five geographically localized regions of high ozone depletion rates, are probably associated with long-term dynamical or temperature changes. Only the equatorial band between +/-20-degrees shows little or no long-term ozone change since January 1979. Ozone time series data have been examined for effect of volcanic eruptions on stratospheric ozone observed by TOMS, with only the Mount Pinatubo stratospheric aerosol injection affecting ozone amounts for a few months after the eruption in June 1991. The TOMS data show no ozone perturbation after the El Chichon eruption, or after any of the other smaller equatorial eruptions, that cannot be explained by interference effects between the annual, El Nino/Southern Oscillation, and Quasi-Biennial Oscillation cycles. The effect of the stratospheric aerosol scattering phase function is clearly seen in the high spatial resolution TOMS ozone data after El Chichon and Mount Pinatubo. Errors caused by the short-term presence of stratospheric aerosols in the TOMS zonally averaged ozone data are less than 1% before correction, and have no significant effect on ozone trend determination. C1 HUGHES STX CORP,LANHAM,MD. RP HERMAN, JR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MAIL CODE 916,GREENBELT,MD 20771, USA. RI McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 48 TC 43 Z9 44 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUL 20 PY 1993 VL 98 IS D7 BP 12783 EP 12793 DI 10.1029/93JD00601 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP166 UT WOS:A1993LP16600016 ER PT J AU RICH, DH RAMMOHAN, K TANG, Y LIN, HT MASERJIAN, J GRUNTHANER, FJ LARSSON, A BORENSTAIN, SI AF RICH, DH RAMMOHAN, K TANG, Y LIN, HT MASERJIAN, J GRUNTHANER, FJ LARSSON, A BORENSTAIN, SI TI ELECTRON-BEAM-INDUCED ABSORPTION MODULATION IMAGING OF STRAINED IN0.2GA0.8AS/GAAS MULTIPLE-QUANTUM WELLS SO APPLIED PHYSICS LETTERS LA English DT Article ID SPATIAL LIGHT MODULATORS; CATHODOLUMINESCENCE; DEFECTS AB We have examined the effects of electron-hole plasma generation on excitonic absorption phenomena in nipi-doped In0.2Ga0.8As/GaAs multiple quantum wells (MQWs) using a novel technique called electron beam-induced absorption modulation imaging. The electron-hole plasma is generated by a high-energy electron beam in a scanning electron microscope and is used as a probe to study the MQW absorption modulation. The influence of structural defects on the diffusive transport of carriers is imaged with a mum-scale resolution. C1 JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. CHALMERS UNIV TECHNOL,DEPT OPTOELECTR & ELECT MEASUREMENTS,S-41296 GOTHENBURG,SWEDEN. JERUSALEM COLL TECHNOL,IL-91160 JERUSALEM,ISRAEL. RP RICH, DH (reprint author), UNIV SO CALIF,DEPT MAT SCI & ENGN,PHOTON MAT & DEVICES LAB,LOS ANGELES,CA 90089, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 12 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 19 PY 1993 VL 63 IS 3 BP 394 EP 396 DI 10.1063/1.110783 PG 3 WC Physics, Applied SC Physics GA LN238 UT WOS:A1993LN23800041 ER PT J AU HAKIMZADEH, R BAILEY, SG AF HAKIMZADEH, R BAILEY, SG TI MINORITY-CARRIER DIFFUSION LENGTH AND EDGE SURFACE-RECOMBINATION VELOCITY IN INP SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SEM AB A scanning electron microscope was used to obtain the electron-beam-induced current (EBIC) profiles in InP specimens containing a Schottky barrier perpendicular to the scanned (edge) surface. An independent technique was used to measure the edge surface-recombination velocity (V(s)). These values were used in a fit of the experimental EBIC data with a theoretical expression for normalized EBIC [C. Donolato, Solid State Electron. 25, 1077 (1982)] to obtain the electron (minority carrier) diffusion length (L(n)). C1 CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP HAKIMZADEH, R (reprint author), SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,BROOKPARK,OH 44142, USA. NR 26 TC 13 Z9 13 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 15 PY 1993 VL 74 IS 2 BP 1118 EP 1123 DI 10.1063/1.354936 PG 6 WC Physics, Applied SC Physics GA LM782 UT WOS:A1993LM78200056 ER PT J AU DOROGY, WE STCLAIR, AK AF DOROGY, WE STCLAIR, AK TI FIBERS FROM A SOLUBLE, FLUORINATED POLYIMIDE SO JOURNAL OF APPLIED POLYMER SCIENCE LA English DT Article AB Polyimide fibers have been produced from both polyamic acid and polyimide resins, derived from 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, by extrusion into various aquesou organic media. Polyimide fibers obtained from polyamic acid fibers after thermal imidization exhibited round or oval cross-sections, while fibers obtained directly from a polyimide resin had dogbone, C-shaped, or oval cross-sections. The effect of polymer inherent viscosity and filament production parameters on the formation of macropores within the filament will be discussed. Tensile properties of fibers, produced under various conditions, are listed and compared. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 8 TC 18 Z9 19 U1 0 U2 6 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0021-8995 J9 J APPL POLYM SCI JI J. Appl. Polym. Sci. PD JUL 15 PY 1993 VL 49 IS 3 BP 501 EP 510 DI 10.1002/app.1993.070490314 PG 10 WC Polymer Science SC Polymer Science GA LH116 UT WOS:A1993LH11600014 ER PT J AU MCCLAIN, CR FIRESTONE, J AF MCCLAIN, CR FIRESTONE, J TI AN INVESTIGATION OF EKMAN UPWELLING IN THE NORTH-ATLANTIC SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID WIND STRESS; OPEN OCEAN; VARIABILITY; SEA AB Surface winds from the Fleet Numerical Oceanography Center (FNOC) for 1979-1986 were used to compute the monthly mean Ekman upwelling fields [w(e)]m, the seasonal and annual climatologies of [w(e)]m ([w(e)]s and [w(e)]a, respectively), and the basin wide monthly mean vertical Ekman velocities [w(e)]mb in the North Atlantic Ocean (the analyses excluded the zone within +/-5-degrees of the equator). The annual climatology compares very well with the climatology of Leetmaa and Bunker (1978). The analyses show a pronounced minimum in [W(e)]mb during 1981-1982. Additional analyses using 1000-mbar winds from the European Centre for Medium-Range Weather Forecasts exhibit a similar pattern in [w(e)]mb. Further examination of the FNOC [w(e)]m fields shows that the primary source of the interannual signal was the region off NW Africa in the vicinity of the Guinea Dome. Other sectors of the basin experienced no significant interannual trends. Hydrographic data and sea surface temperature data from the NW Africa sector for 1981-1986 indicate a cooling trend beginning in late 1982, consistent with increased upwelling. Also, the fall and winter seasons' mixed layers at the center of the Guinea Dome were deeper in 1984 and 1985 than in previous years. Finally, the potential impact of large interannual variations in Ekman upwelling on basin wide primary productivity is discussed. C1 GEN SCI CORP,LAUREL,MD 20707. RP MCCLAIN, CR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,CODE 971,GREENBELT,MD 20771, USA. NR 32 TC 46 Z9 46 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 1993 VL 98 IS C7 BP 12327 EP 12339 DI 10.1029/93JC00868 PG 13 WC Oceanography SC Oceanography GA LN310 UT WOS:A1993LN31000004 ER PT J AU ROTTMAN, JW EINAUDI, F AF ROTTMAN, JW EINAUDI, F TI SOLITARY WAVES IN THE ATMOSPHERE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID STRATIFIED SHEAR FLOWS; MORNING GLORY; NONLINEAR-WAVES; SHALLOW FLUIDS; INTERNAL WAVES; CRITICAL LAYER; GRAVITY-WAVES; UNDULAR BORE; LONG; TOWER AB The weakly nonlinear theory for internal solitary waves is reviewed and theoretical results of the vertical and horizontal structure of temperature, vertical displacements, and vertical and horizontal perturbations to the wind field associated with steadily propagating solitary waves are presented in two idealized atmospheric configurations. One configuration is representative of solitary waves observed in the lower troposphere and the other of solitary waves that occupy the entire troposphere. The important results of the theory are presented in a form that can be readily used by observationalists. The results obtained are then analyzed using actual rawinsonde data for two well-documented observations of atmospheric solitary waves, which are analogous to the two idealized configurations. The importance and difficulties of properly identifying the waveguide within which the solitary wave is confined are discussed. The fundamental role of a critical level in ducting the disturbances and thus in defining the thickness of the waveguide is illustrated in the example dealing with the solitary wave occupying the entire troposphere. Together, these two examples illustrate the decisions and compromises that must be made in applying the theory to the real atmosphere. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 910,GREENBELT,MD 20771. UNIV SPACE RES ASSOC,NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD. NR 47 TC 40 Z9 40 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JUL 15 PY 1993 VL 50 IS 14 BP 2116 EP 2136 DI 10.1175/1520-0469(1993)050<2116:SWITA>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LN108 UT WOS:A1993LN10800003 ER PT J AU CHOU, MD RIDGWAY, WL YAN, MMH AF CHOU, MD RIDGWAY, WL YAN, MMH TI ONE-PARAMETER SCALING AND EXPONENTIAL-SUM FITTING FOR WATER-VAPOR AND CO2 INFRARED TRANSMISSION FUNCTIONS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID NONHOMOGENEOUS ATMOSPHERES; RADIATIVE-TRANSFER; COOLING RATES; ABSORPTION; CONTINUUM AB A medium-sized band model for water vapor and CO2 absorption is developed using the one-parameter scaling approximation. The infrared spectrum is divided into 10 bands. The Planck-weighted diffuse transmittance is reduced to a function dependent only upon the scaled absorber amount and fit by an exponential sum. By selecting specific sets of absorption coefficients for exponential-sum fitting, computations of fluxes and cooling rate are made very fast. Compared to a broadband model, the accuracy, speed, and versatility are all enhanced. With absorption due to water vapor line, continuum, CO2 as well as O3 included, the parameterization introduces an error of <1.5 W m-2 in fluxes and <0.15-degrees-C day-1 in the tropospheric and lower stratospheric cooling rates. RP CHOU, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MAIL CODE 913,GREENBELT,MD 20771, USA. NR 23 TC 22 Z9 24 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JUL 15 PY 1993 VL 50 IS 14 BP 2294 EP 2303 DI 10.1175/1520-0469(1993)050<2294:OPSAES>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LN108 UT WOS:A1993LN10800014 ER PT J AU FREUND, RW ZHA, HY AF FREUND, RW ZHA, HY TI FORMALLY BIORTHOGONAL POLYNOMIALS AND A LOOK-AHEAD LEVINSON ALGORITHM FOR GENERAL TOEPLITZ-SYSTEMS SO LINEAR ALGEBRA AND ITS APPLICATIONS LA English DT Article ID HERMITIAN TOEPLITZ; MARKOV PARAMETERS; COMBINED SEQUENCE; LINEAR-EQUATIONS; MATRICES; DECOMPOSITION; EIGENVALUE; MOMENTS; HANKEL AB Systems of linear equations with Toeplitz coefficient matrices arise in many important applications. The classical Levinson algorithm computes solutions of Toeplitz systems with only O(n2) arithmetic operations, as compared to O(n3) operations that are needed for solving general linear systems. However, the Levinson algorithm in its original form requires that all leading principal submatrices be nonsingular. In this paper, an extension of the Levinson algorithm to general Toeplitz systems is presented. The algorithm uses look-ahead to skip over exactly singular as well as ill-conditioned leading submatrices, and at the same time it still fully exploits the Toeplitz structure. In our derivation of this algorithm, we make use of the intimate connection of Toeplitz matrices with formally biorthogonal polynomials. In particular, the occurrence of singular or ill-conditioned submatrices corresponds to a breakdown or near-breakdown in the standard recurrence relations for biorthogonal polynomials. We present new general recurrence relations that connect successive pairs in any given subsequence of all existing formally biorthogonal polynomials. These recurrences then immediately lead to the proposed look-ahead Levinson algorithm for solving Toeplitz systems. Implementation details for this algorithm and operation counts are given. Numerical experiments for Toeplitz systems with ill-conditioned submatrices are reported. C1 NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035. PENN STATE UNIV,DEPT COMP SCI,UNIV PK,PA 16802. RP FREUND, RW (reprint author), AT&T BELL LABS,600 MT AVE,ROOM 2C-420,MURRAY HILL,NJ 07974, USA. NR 51 TC 20 Z9 20 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0024-3795 J9 LINEAR ALGEBRA APPL JI Linear Alg. Appl. PD JUL 15 PY 1993 VL 188 BP 255 EP 303 DI 10.1016/0024-3795(93)90471-Y PG 49 WC Mathematics, Applied; Mathematics SC Mathematics GA LK509 UT WOS:A1993LK50900010 ER PT J AU LORIMER, DR BAILES, M DEWEY, RJ HARRISON, PA AF LORIMER, DR BAILES, M DEWEY, RJ HARRISON, PA TI PULSAR STATISTICS - THE BIRTHRATE AND INITIAL SPIN PERIODS OF RADIO PULSARS SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE METHODS-STATISTICAL; PULSARS-GENERAL; RADIO CONTINUUM-STARS ID HIGH-FREQUENCY SURVEY; GALACTIC PLANE; BEAMS; LUMINOSITY; EMISSION; SEARCH AB We investigate the birthrate and initial spin periods of radio pulsars using the recently revised pulsar distance scale of Cordes et al. Our technique is based upon the model-free approach originally suggested by Phinney & Blandford, which makes no assumptions about pulsar luminosity as a function of period, the beaming fraction, or field decay in radio pulsars. It eliminates the large statistical errors inherent in previous methods by restricting the sample to pulsars with luminosities greater than some minimum value. We verify the validity of our approach, and shortcomings of previous methods, by using Monte Carlo simulations on synthetic populations of pulsars which take into account random errors in the pulsar distance scale. We find that small-number statistics and errors in the pulsar distance scale prohibit us from making any firm statements on the birthrate or initial spin periods of pulsars with luminosities less than 10 mJy kpc2. The birthrate of potentially observable pulsars with luminosities greater than 10 mJy kpc2 is between 0.6 and 2 per 1000 yr. There is no convincing evidence that any of these pulsars are born spinning slowly. We estimate that there are (1.3 +/- 0.2) x 10(4) potentially observable pulsars in the Galaxy with luminosities > 10 mJy kpC2. Application of Biggs's beaming law to our results suggests that a pulsar is born once every 125 to 250 yr in the Galaxy, considerably lower than recent estimates of a supernova rate of 1 per 30 yr, but consistent with earlier estimates of the supernova rate. The local pulsar birthrate is calculated to be between 6 and 1 2 pulsar kpC-2 Myr-1, which is in excellent agreement with Blauuw's estimate of the local production rate of OB stars. C1 JET PROP LAB,PASADENA,CA 91109. RP LORIMER, DR (reprint author), UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,JODRELL BANK,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. NR 42 TC 175 Z9 175 U1 0 U2 5 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 15 PY 1993 VL 263 IS 2 BP 403 EP 415 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LM294 UT WOS:A1993LM29400015 ER PT J AU MCPETERS, RD GLEASON, JF AF MCPETERS, RD GLEASON, JF TI ERRORS AND OZONE MEASUREMENT SO NATURE LA English DT Letter RP MCPETERS, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MAIL CODE 916,GREENBELT,MD 20771, USA. RI Gleason, James/E-1421-2012; McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 2 TC 2 Z9 2 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 15 PY 1993 VL 364 IS 6434 BP 198 EP 198 DI 10.1038/364198b0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LM683 UT WOS:A1993LM68300040 ER PT J AU ZHANG, B LEMPERT, WR MILES, RB DISKIN, G AF ZHANG, B LEMPERT, WR MILES, RB DISKIN, G TI EFFICIENT VIBRATIONAL RAMAN CONVERSION IN O2 AND N2 CELLS BY USE OF SUPERFLUORESCENCE SEEDING SO OPTICS LETTERS LA English DT Article ID SCATTERING AB We report first-Stokes vibrational conversion efficiency of 21% and 35%, respectively, in high-pressure O2- and N2-stimulated Raman cells. Broadband superfluorescence is employed to seed these Raman cells, significantly increasing the conversion efficiencies with no measured effect on the Raman spectrum. The addition of helium buffer gas reduces competition from stimulated Brillouin scattering and improves the pulse-to-pulse stability and spatial mode quality by increasing the thermal conductivity. Further improvement of the spatial mode quality is achieved by use of gentle heating on the bottom of the cell to induce convection. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP ZHANG, B (reprint author), PRINCETON UNIV,DEPT MECH & AEROSP ENGN,PRINCETON,NJ 08544, USA. NR 10 TC 15 Z9 15 U1 2 U2 6 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD JUL 15 PY 1993 VL 18 IS 14 BP 1132 EP 1134 DI 10.1364/OL.18.001132 PG 3 WC Optics SC Optics GA LL313 UT WOS:A1993LL31300004 PM 19823311 ER PT J AU MEIJER, PHE FORREST, KA AF MEIJER, PHE FORREST, KA TI DETERMINATION OF TRANSPARENCY IN MODULATED STRUCTURES SO PHYSICA A LA English DT Article ID IMPACT IONIZATION; WELL AB In order to obtain a high yield in impact ionization in a superlattice structure, the transition rate of the corresponding process has to be optimized. Since this transition rate is, apart from the magnitude of the pair creation matrix element, determined by the densities of states of the electrons and the holes, it is of importance to operate the device at, or near, the maximum density of states. In this paper we develop a general theory for the calculation and prediction of high densities of states. It is pointed out that the energy at which the density of states is maximum lies close to the energy at which the superstructure is transparent. C1 NASA,GODDARD SPACE FLIGHT CTR,PHOTON BRANCH,GREENBELT,MD 20771. RP MEIJER, PHE (reprint author), CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064, USA. NR 11 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-4371 J9 PHYSICA A JI Physica A PD JUL 15 PY 1993 VL 197 IS 1-2 BP 243 EP 259 DI 10.1016/0378-4371(93)90471-F PG 17 WC Physics, Multidisciplinary SC Physics GA LN698 UT WOS:A1993LN69800018 ER PT J AU SHEBALIN, JV AF SHEBALIN, JV TI HOMOGENEOUS QUANTUM-ELECTRODYNAMIC TURBULENCE SO PHYSICA D-NONLINEAR PHENOMENA LA English DT Article ID COLLINEAR H+H2 REACTION; ISOTROPIC TURBULENCE; DYNAMICS; SCHEMES AB The electromagnetic field equations and Dirac equations for oppositely charged wave functions are numerically time-integrated using a spatial Fourier method. The numerical approach used, a spectral transform technique, is based on a continuum representation of physical space. The coupled classical field equations contain a dimensionless parameter which sets the strength of the non-linear interaction (as the parameter increases, interaction volume decreases). For a parameter value of unity, highly nonlinear behavior in the time-evolution of an individual wave function, analogous to ideal fluid turbulence, is observed. In the truncated Fourier representation which is numerically implemented here, the quantum turbulence is homogeneous but anisotropic and manifests itself in the nonlinear evolution of equilibrium modal spatial spectra for the probability density of each particle and also for the electromagnetic energy density. The results show that nonlinearly interacting fermionic wave functions quickly approach a multi-mode, dynamic equilibrium state, and that this state can be determined by numerical means. RP NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NR 21 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2789 EI 1872-8022 J9 PHYSICA D JI Physica D PD JUL 15 PY 1993 VL 66 IS 3-4 BP 381 EP 391 DI 10.1016/0167-2789(93)90074-B PG 11 WC Mathematics, Applied; Physics, Multidisciplinary; Physics, Mathematical SC Mathematics; Physics GA LQ634 UT WOS:A1993LQ63400006 ER PT J AU ZHANG, J CUI, W JUDA, M MCCAMMON, D KELLEY, RL MOSELEY, SH STAHLE, CK SZYMKOWIAK, AE AF ZHANG, J CUI, W JUDA, M MCCAMMON, D KELLEY, RL MOSELEY, SH STAHLE, CK SZYMKOWIAK, AE TI HOPPING CONDUCTION IN PARTIALLY COMPENSATED DOPED SILICON SO PHYSICAL REVIEW B LA English DT Article ID METAL-INSULATOR-TRANSITION; COULOMB GAP; SI-AS; BOLOMETERS; TRANSPORT; REGION; GE AB We have measured the dc electrical resistance of partially compensated (5-50%)_ion-implanted Si:P,B (both n and p type), over the temperature range 0.05-30 K. The temperature behavior is consistent with the prediction of the model for variable-range hopping (VRH) with a Coulomb gap rho(T)=rho0exp(T0/T)1/2 over a temperature range 6.5 < T0/T < 24. We observe deviations from this behavior at our high- and low-temperature extremes. In the low-temperature region, the resistivities show a stronger temperature dependence than the Coulomb-gap model prediction. The high-temperature deviation appears consistent with a transition from Coulomb-gap VRH to Mott VRH. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP ZHANG, J (reprint author), UNIV WISCONSIN, DEPT PHYS, MADISON, WI 53706 USA. RI Moseley, Harvey/D-5069-2012; Kelley, Richard/K-4474-2012; OI Juda, Michael/0000-0002-4375-9688; Cui, Wei/0000-0002-6324-5772 NR 35 TC 44 Z9 44 U1 0 U2 1 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD JUL 15 PY 1993 VL 48 IS 4 BP 2312 EP 2319 DI 10.1103/PhysRevB.48.2312 PG 8 WC Physics, Condensed Matter SC Physics GA LP540 UT WOS:A1993LP54000032 ER PT J AU CARR, BJ LIDSEY, JE AF CARR, BJ LIDSEY, JE TI PRIMORDIAL BLACK-HOLES AND GENERALIZED CONSTRAINTS ON CHAOTIC INFLATION SO PHYSICAL REVIEW D LA English DT Article ID DIFFERENTIAL MICROWAVE RADIOMETER; REDSHIFT-DISTANCE SAMPLES; LARGE-SCALE STRUCTURE; COLD DARK MATTER; EXTENDED INFLATION; GRAVITATIONAL-WAVES; POWER-LAW; BACKGROUND ANISOTROPY; DENSITY-FLUCTUATIONS; UNIVERSE AB It is argued that the main quantity of interest in chaotic inflation is the cosmological expansion rate H expressed as a function of the inflaton field phi. We derive a general prescription for realizing successful inflation in terms of a set of constraints on this function. The formalism is valid for all chaotic inflationary models based on a single scalar field which is minimally coupled to general relativity, so no restrictions on the dynamics of the field are necessary. This technique is used to investigate the possibility ty that primordial black holes (PBH's) may arise due to adiabatic quantum fluctuations in the inflaton. PBH formation can only be interesting if the amplitude of the fluctuations decreases with increasing mass scale and this is only possible if the field is accelerating or decelerating sufficiently fast. In this case, limits on the number of PBH's place very interesting constraints on the form of H(phi) since, together with the COBE measurement, they restrict the spectrum of fluctuations over 45 decades of mass. This corresponds to 35 e-foldings of inflationary expansion. If the amplitude of the fluctuations decreases as a power of mass, which is the most interesting situation, then H(phi) must have a trigonometric form and this allows the constraints to be expressed very simply. C1 FERMILAB NATL ACCELERATOR LAB,FERMILAB ASTROPHYS CTR,NASA,BATAVIA,IL 60510. RP CARR, BJ (reprint author), SCH MATH SCI,ASTRON UNIT,MILE END RD,LONDON E1 4NS,ENGLAND. NR 71 TC 104 Z9 104 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JUL 15 PY 1993 VL 48 IS 2 BP 543 EP 553 DI 10.1103/PhysRevD.48.543 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LN084 UT WOS:A1993LN08400010 ER PT J AU MAIA, MD SILVEIRA, V AF MAIA, MD SILVEIRA, V TI WINDOW TO EXTRA DIMENSIONS NEAR A BLACK-HOLE SO PHYSICAL REVIEW D LA English DT Note AB A version of the Rubakov-Shaposhnikov high-dimensional model is implemented. Particles are assumed to be confined to a four-dimensional submanifold of a high-dimensional space via an ad hoc potential barrier based on the four-dimensional gravitational field strength. The analogue of the Schwarzschild back hole has a window into the higher-dimensional space, located near where the event horizon would have been. C1 FERMILAB NATL ACCELERATOR LAB,FERMILAB ASTROPHYS CTR,NASA,BATAVIA,IL 60510. UNIV BRASILIA,DEPT FIS,BR-70919 BRASILIA,DF,BRAZIL. RP MAIA, MD (reprint author), UNIV BRASILIA,DEPT MATEMAT,BR-70919 BRASILIA,DF,BRAZIL. OI maia, marcos/0000-0003-0094-7686 NR 20 TC 3 Z9 3 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JUL 15 PY 1993 VL 48 IS 2 BP 954 EP 957 DI 10.1103/PhysRevD.48.954 PG 4 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LN084 UT WOS:A1993LN08400060 ER PT J AU CHOI, SR TIKARE, V SALEM, JA AF CHOI, SR TIKARE, V SALEM, JA TI EFFECT OF ENVIRONMENT ON FRACTURE-TOUGHNESS OF 96 WT-PERCENT ALUMINA SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID STRESS-CORROSION C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. RP CHOI, SR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 12 TC 2 Z9 2 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD JUL 15 PY 1993 VL 29 IS 2 BP 189 EP 192 DI 10.1016/0956-716X(93)90306-D PG 4 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA LF820 UT WOS:A1993LF82000008 ER PT J AU MIELKE, SL TAWA, GJ TRUHLAR, DG SCHWENKE, DW AF MIELKE, SL TAWA, GJ TRUHLAR, DG SCHWENKE, DW TI ENERGY-TRANSFER THROUGH EXCIPLEX FUNNEL STATES SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Note ID COLLISION COMPLEX; SPECTROSCOPY; MOLECULES; SURFACES; DYNAMICS C1 UNIV MINNESOTA,INST SUPERCOMP,CHEM PHYS PROGRAM,DEPT CHEM,MINNEAPOLIS,MN 55455. UNIV MINNESOTA,ARMY HIGH PERFORMANCE COMP RES CTR,MINNEAPOLIS,MN 55455. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 30 TC 35 Z9 35 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD JUL 14 PY 1993 VL 115 IS 14 BP 6436 EP 6437 DI 10.1021/ja00067a079 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA LT173 UT WOS:A1993LT17300079 ER PT J AU KSENDZOV, A FATHAUER, RW GEORGE, T PIKE, WT VASQUEZ, RP TAYLOR, AP AF KSENDZOV, A FATHAUER, RW GEORGE, T PIKE, WT VASQUEZ, RP TAYLOR, AP TI VISIBLE PHOTOLUMINESCENCE OF POROUS SI1-XGEX OBTAINED BY STAIN ETCHING SO APPLIED PHYSICS LETTERS LA English DT Article ID QUANTUM AB We have investigated visible photolumineseence (PL) from thin porous Si1-xGex alloy layers prepared by stain etching of molecular-beam-epitaxy-grown material. Seven samples with nominal Ge fraction x varying from 0.04 to 0.41 were studied at room temperature and 80 K. Samples of bulk stain etched Si and Ge were also investigated. The composition of the porous material was determined using x-ray photoemission spectroscopy and Rutherford backscattering techniques to be considerably more Ge rich than the starting epitaxial layers. While the luminescence intensity drops significantly with the increasing Ge fraction, we observe no significant variation in the PL wavelength at room temperature. This is clearly in contradiction to the popular model based on quantum confinement in crystalline silicon which predicts that the PL energy should follow the band-gap variation of the starting material. However, our data are consistent with small active units containing only a few Si atoms that are responsible for the light emission. Such units are present in many compounds proposed in the literature as the cause of the visible PL in porous Si. C1 RENSSELAER POLYTECH INST,DEPT PHYS,TROY,NY 12181. RP KSENDZOV, A (reprint author), CALTECH,CTR SPACE MICROELECTR TECHNOL,JET PROPULS LAB,PASADENA,CA 91109, USA. NR 13 TC 29 Z9 30 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 12 PY 1993 VL 63 IS 2 BP 200 EP 202 DI 10.1063/1.110368 PG 3 WC Physics, Applied SC Physics GA LL831 UT WOS:A1993LL83100027 ER PT J AU DODELSON, S GRADWOHL, BA AF DODELSON, S GRADWOHL, BA TI HOW EFFECTIVE IS THE EFFECTIVE POTENTIAL SO NUCLEAR PHYSICS B LA English DT Article ID ELECTROWEAK PHASE-TRANSITION; BARYON ASYMMETRY; PERTURBATION-THEORY; FALSE VACUUM; FIELD-THEORY; UNIVERSE; BARYOGENESIS; EXPANSION; SYMMETRY; MODELS AB Motivated by bubble nucleation in first order phase transitions, we question the validity of the effective potential for inhomogeneous configurations. In an attempt to get some insight into the importance of derivative terms, we analyze a simple model, a kink in 1 + 1 dimensions and zero temperature. We evaluate the energy shift from the quantum fluctuations about the non-uniform background (i.e. the effective action) and compare it to the energy from the effective potential. Our results clearly show that for inhomogeneous configurations it may be inadequate to omit derivative terms and confine oneself to the effective potential. We then couple the kink field to an additional scalar field and perform the same comparison. The addition of the second field allows us to vary the mass of the fluctuations and their coupling to the underlying kink. If the mass of the second field is large, it does not feel the inhomogeneities in the kink field and consequently does not give rise to important derivative corrections in the effective action. In contrast, if the mass is small, derivative terms are significant and the effective potential fails. In the latter regime we can, however, rely on the Born approximation to calculate the effective action. C1 UNIV CALIF LOS ANGELES,DEPT PHYS,LOS ANGELES,CA 90024. RP DODELSON, S (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,CTR ASTROPHYS,POB 500,BATAVIA,IL 60510, USA. NR 52 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0550-3213 J9 NUCL PHYS B JI Nucl. Phys. B PD JUL 12 PY 1993 VL 400 IS 1-3 BP 435 EP 459 DI 10.1016/0550-3213(93)90412-I PG 25 WC Physics, Particles & Fields SC Physics GA LM676 UT WOS:A1993LM67600018 ER PT J AU COPELAND, EJ KOLB, EW LIDDLE, AR LIDSEY, JE AF COPELAND, EJ KOLB, EW LIDDLE, AR LIDSEY, JE TI OBSERVING THE INFLATION POTENTIAL SO PHYSICAL REVIEW LETTERS LA English DT Article ID UNIVERSE; PERTURBATIONS AB We show how observations of the density perturbation (scalar) spectrum and the gravitational wave (tensor) spectrum allow a reconstruction of the potential responsible for cosmological inflation. A complete functional reconstruction or a perturbative approximation about a single scale are possible; the suitability of each approach depends on the data available. Consistency equations between the scalar and tensor spectra are derived, which provide a powerful signal of inflation. C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV SUSSEX,SCH MATH & PHYS SCI,CTR ASTRON,BRIGHTON BN1 9QH,E SUSSEX,ENGLAND. RP COPELAND, EJ (reprint author), UNIV SUSSEX,SCH MATH & PHYS SCI,BRIGHTON BN1 9QH,E SUSSEX,ENGLAND. NR 29 TC 75 Z9 75 U1 0 U2 0 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 JUL 12 PY 1993 VL 71 IS 2 BP 219 EP 222 DI 10.1103/PhysRevLett.71.219 PG 4 WC Physics, Multidisciplinary SC Physics GA LM033 UT WOS:A1993LM03300003 ER PT J AU YIN, LI SELTZER, SM AF YIN, LI SELTZER, SM TI TOMOGRAPHIC DECODING ALGORITHM FOR A NONOVERLAPPING REDUNDANT ARRAY SO APPLIED OPTICS LA English DT Article DE TOMOGRAPHY; MULTIPLE-PINHOLE CAMERA ID 7-PINHOLE AB A tomographic reconstruction algorithm is developed for the nonoverlapping redundant array x-ray imaging system whereby the background contributions from out-of-focus planes can be eliminated. The algorithm makes use of two constraints derived from the physical characteristics of the nonoverlapping redundant array system in tandem with the correlation decoding process. It is simple, direct, and noniterative. Tomographic images of computer-generated planar and three-dimensional objects are provided to illustrate the effectiveness of the algorithm. C1 NATL INST STAND & TECHNOL, GAITHERSBURG, MD 20899 USA. RP YIN, LI (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. NR 8 TC 4 Z9 4 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 10 PY 1993 VL 32 IS 20 BP 3726 EP 3735 PG 10 WC Optics SC Optics GA LM078 UT WOS:A1993LM07800013 PM 20830002 ER PT J AU SILK, J STEBBINS, A AF SILK, J STEBBINS, A TI CLUMPY COLD DARK-MATTER SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC STRINGS; COSMOLOGY, THEORY; DARK MATTER; LARGE-SCALE STRUCTURE OF UNIVERSE ID GLOBAL TEXTURE; GALAXIES; UNIVERSE; PROBE AB Clumpiness is likely to be generic to cold dark matter cosmologies. We consider cold dark matter models with cosmic strings and textures appropriate for galaxy formation. CDM clumps with a density of approximately 10(7) M. pc-3 are generated at redshift approximately z(eq) and a sizable fraction of them may survive to today. The most numerous clumps should have dense cores of mass approximately 10(-2) (1 GeV/M(x))3/2 M., where M(x) is the mass of the dark matter particle and might contain up to 10(-3) of the CDM mass. Even in canonical, unseeded cold dark matter models, there is also likely to be clumpiness, developing when the first rare fluctuations go non-linear, and surviving on scales of up to 10(8) M. in galaxy halos. Observable implications include possible dark matter cores in globular clusters, and in galactic nuclei. The enhanced annihilation rate in clumps can lead to a significant contribution to the diffuse gamma-ray background, as well as emission from the Galactic center. Results from terrestrial dark matter detection experiments might be significantly affected by clumpiness in the Galactic halo. C1 UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP SILK, J (reprint author), UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720, USA. OI silk, joe/0000-0002-1566-8148 NR 25 TC 87 Z9 87 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP 439 EP 449 DI 10.1086/172846 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ884 UT WOS:A1993LJ88400001 ER PT J AU NETZER, H AF NETZER, H TI IONIZED ABSORBERS, IONIZED EMITTERS, AND THE X-RAY-SPECTRUM OF ACTIVE GALACTIC NUCLEI SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; X-RAYS, GALAXIES; X-RAYS, GENERAL ID COLD MATTER; RADIATIVE RECOMBINATION; ABSORPTION; NGC-4151; GALAXIES; LINE; HOT; CONSTRAINTS; SIGNATURES; IONS AB Broad absorption features are common in the X-ray spectrum of low-luminosity AGNs. The features have been modeled by leaky neutral absorbers or by highly ionized gas that completely occult the continuum source. Such models are incomplete since they do not take into account all the physical processes in the gas. In particular, no previous model included the X-ray emission by the ionized absorbing gas and the reflection of the continuum source radiation. The present work discusses the emission, absorption, and reflection properties of photoionized gases with emphasis on conditions thought to prevail in AGNs. It shows that such gas is likely to produce intense X-ray line and continuum radiation and to reflect a sizable fraction of the nonstellar continuum at all energies. If such gas is indeed responsible for the observed X-ray absorption, then absorption edges are much weaker than commonly assumed, and some residual X-ray continuum is likely to be observed even if the line of sight is completely blocked. Moreover, X-ray emission features may show up in sources not showing X-ray absorption. This has immense consequences for medium-resolution X-ray missions, such as BBXRT and Astro-D, and for the planned high-resolution experiments on board XMM and AXAF. RP NETZER, H (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. NR 31 TC 119 Z9 119 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP 594 EP 601 DI 10.1086/172861 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ884 UT WOS:A1993LJ88400016 ER PT J AU URRY, CM MARASCHI, L EDELSON, R KORATKAR, A KROLIK, J MADEJSKI, G PIAN, E PIKE, G REICHERT, G TREVES, A WAMSTEKER, W BOHLIN, R BERGMAN, J BRINKMANN, W CHIAPPETTI, L COURVOISIER, T FILIPPENKO, AV FINK, H GEORGE, IM KONDO, Y MARTIN, PG MILLER, HR OBRIEN, P SHULL, JM SITKO, M SZYMKOWIAK, AE TAGLIAFERRI, G WAGNER, S WARWICK, R AF URRY, CM MARASCHI, L EDELSON, R KORATKAR, A KROLIK, J MADEJSKI, G PIAN, E PIKE, G REICHERT, G TREVES, A WAMSTEKER, W BOHLIN, R BERGMAN, J BRINKMANN, W CHIAPPETTI, L COURVOISIER, T FILIPPENKO, AV FINK, H GEORGE, IM KONDO, Y MARTIN, PG MILLER, HR OBRIEN, P SHULL, JM SITKO, M SZYMKOWIAK, AE TAGLIAFERRI, G WAGNER, S WARWICK, R TI MULTIWAVELENGTH MONITORING OF THE BL LACERTAE OBJECT PKS 2155-304 .1. THE IUE CAMPAIGN SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL LACERTAE OBJECTS, INDIVIDUAL (PKS 2155-304); GALAXIES, ACTIVE; ULTRAVIOLET, GALAXIES ID HUBBLE-SPACE-TELESCOPE; RAY ABSORPTION FEATURE; X-RAY; ULTRAVIOLET CALIBRATION; OPTICAL OBSERVATIONS; RAPID VARIABILITY; RELATIVISTIC JETS; LAC OBJECTS; PKS-2155-304; ARTIFACTS AB Daily monitoring of PKS 2155-304 with the IUE satellite throughout 1991 November has revealed dramatic, large-amplitude, rapid variations in the ultraviolet flux of this BL Lac object. Many smaller, rapid flares are superposed on a general doubling of the intensity. During the 5d period when sampling was roughly continuous, the rapid flaring had an apparent quasi-periodic nature, with peaks repeating every approximately 0.d7. The short- and long-wavelength ultraviolet light curves are well correlated with each other, and with the optical light curve deduced from the Fine Error Sensor (FES) on IUE. The formal lag is zero, but the cross-correlation is asymmetric in the sense that the shorter wavelength emission leads the longer. The ultraviolet spectral shape varies a small but significant amount. The correlation between spectral shape and intensity is complicated; an increase in intensity is associated with spectral hardening, but lags behind the spectral change by approximately 1 day. The sign of the correlation is consistent with the nonthermal acceleration processes expected in relativistic plasmas, so that the present results are consistent with relativistic jet models, which can also account for quasi-periodic flaring. In contrast, currently proposed accretion disk models are strongly ruled out by the simultaneous optical and ultraviolet variability. C1 UNIV MILAN,DEPT PHYS,I-20133 MILAN,ITALY. NASA,GSFC,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. NASA,GSFC,UNIV SPACE RES ASSOCIAT,GREENBELT,MD 20771. SISSA,ISAS,INT SCH ADV STUDIES,TRIESTE,ITALY. ESA,IUE OBSERV,E-28080 MADRID,SPAIN. UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. MPE,W-8046 GARCHING,GERMANY. CNR,IST FIS COSM,I-20133 MILAN,ITALY. OBSERV GENEVA,CH-1290 SAUVERNY,SWITZERLAND. NASA,GSFC,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. UNIV TORONTO,CANADIAN INST THEORET ASTROPHYS,TORONTO M5S 1A7,ONTARIO,CANADA. CALTECH,PASADENA,CA 91125. UNIV LONDON UNIV COLL,DEPT PHYS & ASTRON,LONDON WC1E 6BT,ENGLAND. NATL INST STAND & TECHNOL,BOULDER,CO 80309. UNIV CINCINNATI,DEPT PHYS,CINCINNATI,OH 45221. OSSERV ASTRON MERATE,I-20121 MILAN,ITALY. LANDESSTERNWARTE HEIDELBERG KONIGSTUHL,W-6900 HEIDELBERG 1,GERMANY. GEORGIA STATE UNIV,DEPT PHYS,ATLANTA,GA 30303. UNIV COLORADO,JILA,BOULDER,CO 80309. UNIV LEICESTER,DEPT PHYS,LEICESTER LE1 7RH,ENGLAND. RP URRY, CM (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. RI Urry, Claudia/G-7381-2011; OI Urry, Claudia/0000-0002-0745-9792; Tagliaferri, Gianpiero/0000-0003-0121-0723; Pian, Elena/0000-0001-8646-4858 NR 71 TC 82 Z9 82 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP 614 EP 631 DI 10.1086/172864 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ884 UT WOS:A1993LJ88400019 ER PT J AU BREGMAN, JD RANK, D TEMI, P HUDGINS, D KAY, L AF BREGMAN, JD RANK, D TEMI, P HUDGINS, D KAY, L TI 3.3 AND 11.3 MICRON IMAGES OF HD-44179 - EVIDENCE FOR AN OPTICALLY THICK POLYCYCLIC AROMATIC HYDROCARBON DISK SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, INTERSTELLAR, CONTINUUM; ISM, INDIVIDUAL (RED RECTANGLE); ISM, MOLECULES; STARS, INDIVIDUAL (HD-44179) ID EMISSION FEATURES; INFRARED-SPECTRUM; RED RECTANGLE; IRAS SOURCES; SPECTROSCOPY; NGC-7027; NEBULAE; CARBON; BANDS; DUST AB Images of HD 44179 (the Red Rectangle) obtained in the 3.3 and 11.3 mum emission bands show two different spatial distributions. The 3.3 mum band image is centrally peaked and slightly extended N-S while the 11.3 mum image shows a N-S bipolar shape with no central peak. If the 3.3 mum band image shows the intrinsic emission of the 11.3 mum band, then the data suggest absorption of the 11.3 mum emission near the center of HD 44179 by a disk with an optical depth of about 1, making HD 44179 the first object in which the infrared emission bands have been observed to be optically thick. Since there is no evidence of absorption of the 3.3 mum emission band by the disk, the absorption cross section of the 3.3 mum band must be substantially less than for the 11.3 mum band. Since the 3.3 and 11.3 mum bands are thought to arise from different size PAHs, the similar N-S extents of the two images implies that the ratio of small to large PAHs does not change substantially with distance from the center. C1 UCSC,UCO,SANTA CRUZ,CA 95064. COLUMBIA UNIV BARNARD COLL,DEPT PHYS,NEW YORK,NY 10027. UCSC,LICK OBSERV,SANTA CRUZ,CA 95064. RP BREGMAN, JD (reprint author), NASA,AMES RES CTR,MS245-6,MOFFETT FIELD,CA 94035, USA. NR 20 TC 27 Z9 27 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP 794 EP 796 DI 10.1086/172882 PN 1 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ884 UT WOS:A1993LJ88400037 ER PT J AU NEUKIRCH, T HESSE, M AF NEUKIRCH, T HESSE, M TI BIFURCATION-ANALYSIS OF A SIMPLE ANALYTIC MODEL OF SELF-PROPAGATING STAR-FORMATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, FORMATION ID ERUPTIVE PROCESSES; DETONATION-WAVES; SPIRAL GALAXIES; EVOLUTION; PLASMAS; ONSET AB We investigate the structure and stability of rotationally symmetric nonhomogeneous time-independent solutions derived from a simple analytic model of self-propagating star formation. For this purpose we employ two methodologies: We use bifurcation theoretical methods to prove the existence of nonhomogeneous axisymmetric stationary solutions of an appropriate nonlinear evolution equation for the stellar density. We show that the nonhomogeneous solution branch bifurcates from the homogeneous one at a critical parameter value of the star formation rate. Further, the analytical theory allows us to show that the new solution set is stable in the weakly nonlinear regime near the bifurcation point. To follow the solution branch further, we use numerical methods. The numerical calculation shows the structure and stability of these solutions. We conclude that no periodic time-dependent solutions of this special model exist, and no further bifurcations can be found. The same results have been found in simulations of stochastic self-propagating star formation based on similar models. Therefore, our findings provide a natural explanation, why long-lived large-scale structure have not been found in those simulations. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP NEUKIRCH, T (reprint author), RUHR UNIV BOCHUM,INST THEORET PHYS 4,W-4630 BOCHUM,GERMANY. RI Neukirch, Thomas/C-1981-2009; Hesse, Michael/D-2031-2012 OI Neukirch, Thomas/0000-0002-7597-4980; NR 24 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP 840 EP 847 DI 10.1086/172887 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ884 UT WOS:A1993LJ88400042 ER PT J AU SHORE, SN ALTNER, B BOLTON, CT CARDELLI, JA EBBETS, DC AF SHORE, SN ALTNER, B BOLTON, CT CARDELLI, JA EBBETS, DC TI GODDARD HIGH-RESOLUTION SPECTROGRAPH OBSERVATIONS OF NARROW DISCRETE STELLAR WIND ABSORPTION FEATURES IN THE ULTRAVIOLET-SPECTRUM OF THE 07.5-III STAR XI-PERSEI SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EARLY-TYPE; STARS, INDIVIDUAL (XI-PERSEI); STARS, MASS LOSS; ULTRAVIOLET, STARS ID DRIVEN WINDS; ZETA-PERSEI; MODEL AB We report the observation of transient narrow absorption components (NACs) in the stellar wind of the O giant xi Per. Two sets of GHRS observations of the Si IV ultraviolet resonance doublet have been obtained. These features are extremely weak, with column densities of approximately 10(12) cm-2 and optical depths of order 0. 1. The features are narrow, less-than-or-equal-to 30 km s-1, and seem to occur in groups. If the NACs are due to the 1393 angstrom component, they represent previously undetected low-velocity discrete absorption components at v(rad) < -600 km s-1. If they are high-velocity features on the 1402 angstrom doublet component, they may represent the decay phase of the discrete absorption components at the terminal velocity. In either case, they are a new aspect of the NAC phenomenon that could not have been detected with previous ultraviolet spectrographs. C1 APPL RES CORP,LANDOVER,MD 20785. UNIV TORONTO,DAVID DUNLAP OBSERV,RICHMOND HILL L4C 4Y6,ONTARIO,CANADA. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. BALL AEROSP SYST GRP,BOULDER,CO. RP SHORE, SN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRONOMY PROGRAMS,GHRS SCI TEAM,CODE 681,GREENBELT,MD 20771, USA. NR 20 TC 2 Z9 2 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP 864 EP 868 DI 10.1086/172889 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ884 UT WOS:A1993LJ88400044 ER PT J AU KALLMAN, TR SCHLEGEL, EM SERLEMITSOS, PJ PETRE, R MARSHALL, F JAHODA, K BOLDT, EA HOLT, SS MUSHOTZKY, RF SWANK, J SZYMKOWIAK, AE KELLEY, RL SMALE, A ARNAUD, K WEAVER, K PAERELS, FB AF KALLMAN, TR SCHLEGEL, EM SERLEMITSOS, PJ PETRE, R MARSHALL, F JAHODA, K BOLDT, EA HOLT, SS MUSHOTZKY, RF SWANK, J SZYMKOWIAK, AE KELLEY, RL SMALE, A ARNAUD, K WEAVER, K PAERELS, FB TI BROAD-BAND X-RAY TELESCOPE OBSERVATIONS OF THE MAGNETIC CATACLYSMIC VARIABLE H0538+608 = BY CAMELOPARDALIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE NOVAE, CATACLYSMIC VARIABLES; STARS, INDIVIDUAL (BY CAMELOPARDALIS); X-RAYS, STARS ID AM HERCULIS; SPECTRUM; BINARIES; CATALOG; POLARS; MODELS AB We report on BBXRT observations of the cataclysmic variable H0538+608 (=BY Cam). The unexcelled energy resolution of BBXRT in the vicinity of the iron K line allows the line strength and energy to be constrained more tightly than has previously been possible. We are able to rule out a significant contribution from fluorescence on iron more neutral than Fe XVIII. Implications for the conditions in the accreting gas are discussed. C1 UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. RP KALLMAN, TR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Jahoda, Keith/D-5616-2012; Swank, Jean/F-2693-2012; Kelley, Richard/K-4474-2012 NR 24 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP 869 EP 873 DI 10.1086/172890 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ884 UT WOS:A1993LJ88400045 ER PT J AU SCHAEFER, BE AF SCHAEFER, BE TI VISIBILITY OF SUNSPOTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUNSPOTS AB The premier record of long-term solar activity is the sunspot count. This paper will develop a theoretical model of sunspot visibility, collect many large sets on sunspot visibility, test the model against the observations, and develop recommendations for improvements in the calculation of the sunspot count. The theoretical model uses thresholds of visibility from physiological studies, equation governing the effects of telescope optics, and the average properties of sunspots. The result is a predicted threshold size for sunspot visibility with the unaided (but filtered) eye, direct vision through a telescope, pinhole camera, and telescope projection. This paper also reports on over 3250 days of sunspot observations from six observers, 38 yr of daily observations by an experienced observer, 1837 days of observations from a network with over 50 experienced observers, observations from 30 inexperienced observers, as well as summaries of results from 102 AAVSO solar observers. The comparison of the observed thresholds with the predicted thresholds reveals agreement to within the uncertainties, so that the model is validated by observation. To improve the stability of the K factor, it is recommended that only small telescopes (or aperture less than roughly 5 cm) be used, and only at high magnification. For telescope observations, the K-correction factor is accurately given by 14.0/(10 + rho), where rho is the average number of spots in a group as reported by the observer. This formulation for the K factor is not susceptible to long-term drifts and is accurate to roughly 12%. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 39 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP 909 EP 919 DI 10.1086/172895 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ884 UT WOS:A1993LJ88400050 ER PT J AU SCARGLE, JD STEIMANCAMERON, T YOUNG, K DONOHO, DL CRUTCHFIELD, JP IMAMURA, J AF SCARGLE, JD STEIMANCAMERON, T YOUNG, K DONOHO, DL CRUTCHFIELD, JP IMAMURA, J TI THE QUASI-PERIODIC OSCILLATIONS AND VERY-LOW FREQUENCY NOISE OF SCORPIUS X-1 AS TRANSIENT CHAOS - A DRIPPING HANDRAIL SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; CHAOTIC PHENOMENA; METHODS, DATA ANALYSIS; STARS, NEUTRON; X-RAYS, STARS ID X-RAY BINARIES; TIME-SERIES AB We present evidence that the quasi-periodic oscillations (QPO) and very low frequency noise (VLFN) characteristic of many accretion sources are different aspects of the same physical process. We analyzed a long, high time resolution EXOSAT observation of the low-mass X-ray binary (LMXB) Sco X-1. The X-ray luminosity varies stochastically on time scales from milliseconds to hours. The nature of this variability-as quantified with both power spectrum analysis and a new wavelet technique, the scalegram-agrees well with the dripping handrail accretion model, a simple dynamical system which exhibits transient chaos. In this model both the QPO and VLFN are produced by radiation from blobs with a wide size distribution, resulting from accretion and subsequent diffusion of hot gas, the density of which is limited by an unspecified instability to lie below a threshold. C1 STANFORD UNIV,DEPT STAT,STANFORD,CA 94305. SANTA FE INST,SANTA FE,NM 87501. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. UNIV OREGON,INST THEORET SCI,EUGENE,OR 97403. UNIV OREGON,DEPT PHYS,EUGENE,OR 97403. RP SCARGLE, JD (reprint author), NASA,DIV SPACE SCI,THEORET STUDIES BRANCH,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 20 TC 49 Z9 50 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP L91 EP L94 DI 10.1086/186920 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ885 UT WOS:A1993LJ88500010 ER PT J AU WICKRAMASINGHE, WADT NEMIROFF, RJ NORRIS, JP KOUVELIOTOU, C FISHMAN, GJ MEEGAN, CA WILSON, RB PACIESAS, WS AF WICKRAMASINGHE, WADT NEMIROFF, RJ NORRIS, JP KOUVELIOTOU, C FISHMAN, GJ MEEGAN, CA WILSON, RB PACIESAS, WS TI THE CONSISTENCY OF STANDARD COSMOLOGY AND THE BATSE NUMBER VERSUS BRIGHTNESS RELATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY, OBSERVATIONS; GAMMA RAYS, BURSTS ID GAMMA-RAY BURSTS AB The integrated number peak-flux relation measured by the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory is compared with several standard cosmological distributions for gamma-ray bursts (GRBs). Friedmann-Robertson-Walker models were used along with the assumption that the bursts are standard candles and have no number or luminosity evolution. For a given OMEGA and spectral shape, we used a free parameter, essentially the comoving number density of bursts, to generate a best fit between the cosmology and the measured relation. Our results are shown for a subsample of the first 260 GRBs recorded by BATSE. We find acceptable fits between simple cosmological models and the brightness distribution data, as determined by the Kolmogorov-Smirnov one-distribution statistical test. One cannot distinguish a single best cosmological model from the goodness of the fits. The best fit implies that BATSE GRBs arc complete out to a redshift of about unity. However, significantly higher and lower redshifts, by as much as a factor of 2, are possible for other marginally acceptable fits. C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP WICKRAMASINGHE, WADT (reprint author), UNIV PENN,PHILADELPHIA,PA 19104, USA. OI Nemiroff, Robert/0000-0002-4505-6599 NR 29 TC 63 Z9 63 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1993 VL 411 IS 2 BP L55 EP L58 DI 10.1086/186911 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ885 UT WOS:A1993LJ88500001 ER PT J AU VANDEGRIEND, AA OWE, M AF VANDEGRIEND, AA OWE, M TI DETERMINATION OF MICROWAVE VEGETATION OPTICAL DEPTH AND SINGLE SCATTERING ALBEDO FROM LARGE-SCALE SOIL-MOISTURE AND NIMBUS SMMR SATELLITE-OBSERVATIONS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID MONITORING VEGETATION; DIELECTRIC SPECTRUM; SENEGALESE SAHEL; EMISSION; SENSITIVITY; PHENOLOGY; CANOPIES; MODEL AB The single scattering albedo and optical depth of typical savanna vegetation in Botswana (Africa) have been determined by inverse modelling using satellite observed microwave signatures and surface soil moisture. Soil emissivity was modelled using a multi-layer radiative transfer model. The study is based on large scale surface moisture data and Nimbus/SMMR 6.6 GHz and 37 GHz dual polarized brightness temperatures over a 3-year period. As compared to the optical depths, the derived single scattering albedos displayed only minor seasonal variations, whereas the values fit well within the range reported in the literature from laboratory and field experiments. Both 6.6 and 37 GHz optical depths were found to be significantly related to NDVI-values derived from NOAA/AVHRR. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771. RP VANDEGRIEND, AA (reprint author), FREE UNIV AMSTERDAM,INST EARTH SCI,1081 HV AMSTERDAM,NETHERLANDS. NR 31 TC 34 Z9 34 U1 0 U2 5 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 10 PY 1993 VL 14 IS 10 BP 1875 EP 1886 PG 12 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA LR848 UT WOS:A1993LR84800004 ER PT J AU KERR, YH NJOKU, EG AF KERR, YH NJOKU, EG TI ON THE USE OF PASSIVE MICROWAVES AT 37 GHZ IN REMOTE-SENSING OF VEGETATION SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID AVHRR DATA; EMISSION AB Recently, a number of studies have investigated the use of the 37 GHz channels of the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) for vegetation monitoring and for studying synergisms between the SMMR and the NOAA Advanced Very High Resolution Radiometer (AVHRR). The approaches are promising but raise a number of issues concerning interpretation of the results, specifically on the relative effects of vegetation and other surface and atmospheric characteristics on the observed signal. This article analyses the 37 GHz Microwave Polarization Difference Temperature (MPDT) in terms of its sensitivity to surface and atmospheric parameters. For this, a radiative transfer model is used which indicates some limitations of the MPDT index and suggests the importance of accounting for atmospheric effects in the data analysis. An alternative approach to the MPDT, including lower SMMR frequencies than 37 GHz, is discussed. C1 JET PROP LAB,PASADENA,CA 91109. RP KERR, YH (reprint author), CNRS,CNES,ETUD & RECH TELEDETECT SPATIALE LAB,F-31055 TOULOUSE,FRANCE. NR 13 TC 27 Z9 32 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 10 PY 1993 VL 14 IS 10 BP 1931 EP 1943 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA LR848 UT WOS:A1993LR84800008 ER PT J AU HOEGY, WR PESNELL, WD WOODS, TN ROTTMAN, GJ AF HOEGY, WR PESNELL, WD WOODS, TN ROTTMAN, GJ TI HOW ACTIVE WAS SOLAR CYCLE-22 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LANGMUIR PROBE; EUV; FLUX AB Solar EUV observations from the Langmuir probe on Pioneer Venus Orbiter suggest that at EUV wavelengths solar cycle 22 was more active than solar cycle 21. The Langmuir probe, acting as a photodiode, measured the integrated solar EUV flux over a 13 1/2 year period from January 1979 to June 1992, the longest continuous solar EUV measurement. The Ipe EUV flux correlated very well with the SME measurement of L(alpha) during the lifetime of SME and with the UARS SOLSTICE L(alpha) from October 1991 to June 1992 when the Ipe measurement ceased. Starting with the peak of solar cycle 21, there was good general agreement of Ipe EUV with the 10.7 cm, Ca K, and He 10830 solar indices, until the onset of solar cycle 22. From 1989 to the start of 1992, the 10.7 cm flux exhibited a broad maximum consisting of two peaks of nearly equal magnitude, whereas Ipe EUV exhibited a strong increase during this time period making the second peak significantly-higher than the first. The only solar index that exhibits the same increase in solar activity as Ipe EUV and L(alpha) during the cycle 22 peak is the total magnetic flux. The case for high activity during this peak is also supported by the presence of very high solar flare intensity. RP HOEGY, WR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES BRANCH,CODE 914,GREENBELT,MD 20771, USA. RI Pesnell, William/D-1062-2012 OI Pesnell, William/0000-0002-8306-2500 NR 12 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 9 PY 1993 VL 20 IS 13 BP 1335 EP 1338 DI 10.1029/93GL01453 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LN476 UT WOS:A1993LN47600002 ER PT J AU PESNELL, WD OMIDVAR, K HOEGY, WR AF PESNELL, WD OMIDVAR, K HOEGY, WR TI MOMENTUM-TRANSFER COLLISION FREQUENCY OF O+-O SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MILLSTONE HILL; IONOSPHERE AB The interaction of the thermosphere and ionosphere is largely governed by collisions between ions and neutral particles. On Venus and the Earth, O+ is a dominant ion, and atomic O dominates throughout much of the thermosphere; therefore an accurate O+-O cross section is an important prerequisite for understanding the dynamics of planetary upper atmospheres. The cross section and momentum transfer collision frequency are calculated with a quantum mechanical code which includes resonance charge exchange, polarization, and charge-quadrupole effects. Our results agree well with earlier calculations of Stubbe [1968] and Stallco et al. [1991]. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP PESNELL, WD (reprint author), APPL RES CORP,8201 CORP DR,SUITE 1120,LANDOVER,MD 20785, USA. RI Pesnell, William/D-1062-2012 OI Pesnell, William/0000-0002-8306-2500 NR 18 TC 64 Z9 64 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 9 PY 1993 VL 20 IS 13 BP 1343 EP 1346 DI 10.1029/93GL01597 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LN476 UT WOS:A1993LN47600004 ER PT J AU DEMORE, WB AF DEMORE, WB TI RATE CONSTANTS FOR THE REACTIONS OF OH WITH HFC-134A (CF3CH2F) AND HFC-134 (CHF2CHF2) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID METHYL CHLOROFORM; METHANE AB Rate constants for the reactions of OH with HFC-134a (CF3CH2F) have been measured relative to CH3CCl3, CH4 and HFC-125 (CF3CHF2). Rate constants for HFC-134 (CF2HCF2H) were measured relative to CH3CCl3, HFC-125, and HFC-134a. The measurements were made in a slow-flow, temperature controlled photochemical reactor, and were based on relative rates of disappearance of the parent compounds as measured by FTIR spectroscopy. The temperature range was 298-358 K. Hydroxyl radicals were generated by 254 nm photolysis of O3 in the presence of water vapor. Using current NASA/JPL rate constants for the reference compounds, temperature dependent rate constants of both compounds were derived. Rate constants obtained from the different reference compounds are in excellent agreement. The presently recommended rate constant for HFC-134a [JPL 92-20, 1992, IUPAC, 1992] is too high by about 25%. RP DEMORE, WB (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 11 TC 19 Z9 19 U1 2 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 9 PY 1993 VL 20 IS 13 BP 1359 EP 1362 DI 10.1029/93GL01336 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LN476 UT WOS:A1993LN47600008 ER PT J AU PRICE, C AF PRICE, C TI GLOBAL SURFACE TEMPERATURES AND THE ATMOSPHERIC ELECTRICAL CIRCUIT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID THUNDERSTORMS AB To monitor future global temperature trends, it would be extremely useful if parameters nonlinearly related to surface temperature could be found, thereby amplifying any warming signal that may exist. Evidence that global thunderstorm activity is nonlinearly related to diurnal, seasonal and interannual temperature variations is presented. Since global thunderstorm activity is also well correlated with the earth's ionospheric potential, it appears that variations of ionospheric potential, that can be measured at a single location, may be able to supply valuable information regarding global surface temperature fluctuations. The observations presented enable a prediction that a 1% (almost-equal-to 3K) increase in global surface temperatures may result in a 20% (almost-equal-to 50KV increase in ionospheric potential. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP PRICE, C (reprint author), COLUMBIA UNIV,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 21 TC 83 Z9 87 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 9 PY 1993 VL 20 IS 13 BP 1363 EP 1366 DI 10.1029/93GL01774 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LN476 UT WOS:A1993LN47600009 ER PT J AU STOTHERS, RB AF STOTHERS, RB TI FLOOD BASALTS AND EXTINCTION EVENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CRETACEOUS TERTIARY BOUNDARY; PERMIAN-TRIASSIC BOUNDARY; POLARITY TIME-SCALE; SIBERIAN TRAPS; RAPID ERUPTION; AGE; VOLCANISM; GEOCHRONOLOGY; SYNCHRONISM; PERIODICITY AB The largest known effusive eruptions during the Cenozoic and Mesozoic Eras, the voluminous flood basalts, have long been suspected as being associated with major extinctions of biotic species. Despite the possible errors attached to the dates in both time series of events, the significance level of the suspected correlation is found here, by an objective, direct method, to be 1% to 4%. Statistically, extinctions lag eruptions by a mean time interval that is indistinguishable from zero, being much less than the average residual derived from the correlation analysis. Oceanic flood basalts, however, must have had a different biological impact, which is still uncertain owing to the small number of known examples and differing physical factors. Although not all continental flood basalts can have produced major extinction events, the non-correlating eruptions (including most or all of the oceanic flood basalts) may have led to smaller marine extinciton events that terminated at least some of the less catastrophically ending geologic stages. Consequently, the 26 Myr quasiperiodicity seen in major marine extinctions may be only a sampling effect, rather than a manifestation of underlying periodicity. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 43 TC 54 Z9 60 U1 2 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 9 PY 1993 VL 20 IS 13 BP 1399 EP 1402 DI 10.1029/93GL01381 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LN476 UT WOS:A1993LN47600018 ER PT J AU MARDER, SR PERRY, JW BOURHILL, G GORMAN, CB TIEMANN, BG MANSOUR, K AF MARDER, SR PERRY, JW BOURHILL, G GORMAN, CB TIEMANN, BG MANSOUR, K TI RELATION BETWEEN BOND-LENGTH ALTERNATION AND 2ND ELECTRONIC HYPERPOLARIZABILITY OF CONJUGATED ORGANIC-MOLECULES SO SCIENCE LA English DT Article ID CRYSTAL-STRUCTURE; POLYACETYLENE AB The solvent dependence of the second hyperpolarizability, gamma, of a variety of unsaturated organic compounds has been measured by third harmonic generation at 1907 nanometers. It is seen that the measured gamma is a function of solvent polarity. These solvent-dependent hyperpolarizabilities are associated with changes in molecular geometry from a highly bond-length alternated, polyene-like structure for a formyl-substituted compound in nonpolar solvents, to a cyanine-like structure, with little bond-length alternation, for a dicyanovinyl-substituted compound in polar solvents. By tuning bond-length alternation, gamma can be optimized in either a positive or negative sense for polymethine dyes of a given conjugation length. C1 CALTECH,BECKMAN INST,PASADENA,CA 91125. RP MARDER, SR (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. RI Gorman, Christopher/A-3463-2008; Perry, Joseph/B-7191-2011 OI Gorman, Christopher/0000-0001-7367-2965; Perry, Joseph/0000-0003-1101-7337 NR 28 TC 344 Z9 344 U1 6 U2 42 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUL 9 PY 1993 VL 261 IS 5118 BP 186 EP 189 DI 10.1126/science.261.5118.186 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LL596 UT WOS:A1993LL59600032 PM 17829273 ER PT J AU LEE, TJ RENDELL, AP AF LEE, TJ RENDELL, AP TI AB-INITIO CHARACTERIZATION OF CLOOH - IMPLICATIONS FOR ATMOSPHERIC CHEMISTRY SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; OZONE DEPLETION; BRANCHING RATIO; 2ND-ROW ATOMS; ROW ATOMS; OH; HYDROGEN; CL2O2; CIO AB The equilibrium structure, dipole moment, harmonic vibrational frequencies, and infrared intensities of ClOOH are determined using the CCSD(T) (singles and doubles coupled-cluster theory plus a perturbational estimate of the effects of connected triple excitations) electronic structure method in conjunction with a TZ2P (triple xi plus double polarization) basis set. The heat of formation of ClOOH is determined (using two different isodesmic reactions) to be +1.5 +/- 1 kcal/mol at 0 K or +0.2 +/- 1 kcal/mol at 298.15 K. Using the computed heat of formation, we examined the stability of ClOOH with respect to the ClO + OH, ClOO + H, and HOO + Cl dissociation limits. Since ClOOH is found to be quite stable, it is argued that the chemistry of ClOOH should be included in any accurate modeling of the stratosphere. C1 SERC, DARESBURY LAB, WARRINGTON WA4 4AD, CHESHIRE, ENGLAND. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Rendell, Alistair/A-4883-2008; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; NR 34 TC 39 Z9 40 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUL 8 PY 1993 VL 97 IS 27 BP 6999 EP 7002 DI 10.1021/j100129a014 PG 4 WC Chemistry, Physical SC Chemistry GA LV578 UT WOS:A1993LV57800014 ER PT J AU SALAMA, F ALLAMANDOLA, LJ AF SALAMA, F ALLAMANDOLA, LJ TI NEUTRAL AND IONIZED POLYCYCLIC AROMATIC-HYDROCARBONS, DIFFUSE INTERSTELLAR BANDS AND THE ULTRAVIOLET EXTINCTION CURVE SO JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS LA English DT Article; Proceedings Paper CT 28TH FARADAY SYMP ON CHEMISTRY IN THE INTERSTELLAR MEDIUM CY DEC 16-18, 1992 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND HO UNIV BIRMINGHAM ID VIBRONIC ABSORPTION-SPECTRA; ION RADICALS; SOLID ARGON; NAPHTHALENE; EMISSION; FEATURES; PYRENE; PHOTOELECTRON; CARRIERS; CATIONS AB Neutral naphthalene (C10H8), phenanthrene (C14H10) and pyrene (C16H10) absorb strongly in the ultraviolet region and may contribute to the extinction curve. High abundances are required to produce detectable structures. The cations of these polycyclic aromatic hydrocarbons (PAHs) absorb in the visible. C10H8+ has 13 discrete absorption bands which fall between 6800 and 4500 angstrom. The strongest band at 6741 angstrom falls close to the weak 6742 angstrom diffuse interstellar band (DIB) Five other weaker bands also match DIBs. The possibility that C10H8+ is responsible for some of the DIBs can be tested by searching for new DIBs at 6520 and 6151 angstrom, other strong naphthalene cation band positions. If C10H8+ is indeed responsible for the 6742 angstrom feature, it accounts for 0.3% of the cosmic carbon. The spectrum of C16H10+ is dominated by a strong band at 4435 angstrom in an Ar matrix and 4395 angstrom in Ne, wavelengths which fall very close to the strongest DIB at 4430 angstrom. If C16H10+, or a closely related pyrene-like ion, is indeed responsible for the 4430 angstrom feature, it accounts for 0.2% of the cosmic carbon. An intense, very broad UV-to-visible continuum is reported which is associated with both ions and could explain how PAHs convert interstellar UV and visible radiation into IR radiation. C1 NASA,AMES RES CTR,DIV SPACE SCI,MS 245-6 MOFFETT FIELD,MOFFETT FIELD,CA 94035. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 41 TC 53 Z9 53 U1 0 U2 1 PU ROYAL SOC CHEMISTRY PI CAMBRIDGE PA THOMAS GRAHAM HOUSE, SCIENCE PARK MILTON ROAD, CAMBRIDGE, CAMBS, ENGLAND CB4 4WF SN 0956-5000 J9 J CHEM SOC FARADAY T JI J. Chem. Soc.-Faraday Trans. PD JUL 7 PY 1993 VL 89 IS 13 BP 2277 EP 2284 DI 10.1039/ft9938902277 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LM947 UT WOS:A1993LM94700017 ER PT J AU PARMAR, DS HOLMES, HK AF PARMAR, DS HOLMES, HK TI PRESSURE-DEPENDENCE OF THE ELECTROOPTIC RESPONSE FUNCTION IN PARTIALLY EXPOSED POLYMER-DISPERSED FERROELECTRIC LIQUID-CRYSTALS SO APPLIED PHYSICS LETTERS LA English DT Article AB Ferroelectric liquid crystals in a new configuration, termed partially exposed polymer dispersed ferroelectric liquid crystal (PEPDFLC), respond to external pressures and demonstrate pressure-induced electro-optic switching response. When the PEPDFLC thin film is sandwiched between two transparent conducting electrodes, one a glass plate and the other a flexible sheet such as polyvenylidene fluoride, the switching characteristics of the thin film are a function of the pressure applied to the flexible transparent electrode and the bias voltage across the electrodes. Response time measurements reveal a linear dependence of the change in electric field with external pressure. C1 OLD DOMINION UNIV,DEPT MECH ENGN & MECH,NORFOLK,VA 23529. RP PARMAR, DS (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23687, USA. NR 7 TC 5 Z9 6 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 5 PY 1993 VL 63 IS 1 BP 21 EP 23 DI 10.1063/1.109737 PG 3 WC Physics, Applied SC Physics GA LK406 UT WOS:A1993LK40600008 ER PT J AU ALTEROVITZ, SA SIEG, RM PAMULAPATI, J BHATTACHARYA, PK AF ALTEROVITZ, SA SIEG, RM PAMULAPATI, J BHATTACHARYA, PK TI ELLIPSOMETRIC CHARACTERIZATION OF IN0.52AL0.48AS AND OF MODULATION-DOPED FIELD-EFFECT TRANSISTOR STRUCTURES ON INP SUBSTRATES (VOL 62, PG 1411, 1993) SO APPLIED PHYSICS LETTERS LA English DT Correction, Addition C1 CLEVELAND STATE UNIV,DEPT ELECT ENGN,CLEVELAND,OH 44115. UNIV MICHIGAN,ANN ARBOR,MI 48109. RP ALTEROVITZ, SA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 5 PY 1993 VL 63 IS 1 BP 121 EP 121 DI 10.1063/1.110820 PG 1 WC Physics, Applied SC Physics GA LK406 UT WOS:A1993LK40600043 ER PT J AU GLOECKLER, G GEISS, J BALSIGER, H FISK, LA GALVIN, AB IPAVICH, FM OGILVIE, KW VONSTEIGER, R WILKEN, B AF GLOECKLER, G GEISS, J BALSIGER, H FISK, LA GALVIN, AB IPAVICH, FM OGILVIE, KW VONSTEIGER, R WILKEN, B TI DETECTION OF INTERSTELLAR PICK-UP HYDROGEN IN THE SOLAR-SYSTEM SO SCIENCE LA English DT Article ID WIND; SPACE; IONS AB Interstellar hydrogen ionized primarily by the solar wind has been detected by the SWICS instrument on the Ulysses spacecraft at a distance of 4.8 astronomical units from the sun. This ''pick-up'' hydrogen is identified by its distinct velocity distribution function, which drops abruptly at twice the local solar wind speed. From the measured fluxes of pick-up protons and singly charged helium, the number densities of neutral hydrogen and helium in the distant regions of the solar system are estimated to be 0.077 +/- 0.015 and 0.013 +/- 0.003 per cubic centimeter, respectively. C1 UNIV BERN,INST PHYS,CH-3012 BERN,SWITZERLAND. NASA,OFF SPACE SCI & APPLICAT,WASHINGTON,DC 20546. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20770. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. RP GLOECKLER, G (reprint author), UNIV MARYLAND,DEPT PHYS,COLL PK,MD 20742, USA. RI Von Steiger, Rudolf/F-6822-2011; Galvin, Antoinette/A-6114-2013 OI Von Steiger, Rudolf/0000-0002-3350-0023; NR 21 TC 237 Z9 239 U1 2 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUL 2 PY 1993 VL 261 IS 5117 BP 70 EP 73 DI 10.1126/science.261.5117.70 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LK434 UT WOS:A1993LK43400032 PM 17750548 ER PT J AU MORRISON, D AF MORRISON, D TI AN INTERNATIONAL PROGRAM TO PROTECT THE EARTH FROM IMPACT CATASTROPHE - INITIAL STEPS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB NASA has recently completed a study of initial steps to deal with possible cosmic impact hazards. It is generally accepted that impacts by Earth-approaching asteroids and comets pose a significant hazard to life and property, with the greatest risk associated with objects large enough to disturb the Earth's climate on a global scale by injecting large quantities of dust into the stratosphere. Various studies have suggested that the minimum mass impacting body to produce such global consequences in tens of billions of tons, resulting in an explosion with energy approaching a million megatons of TNT. The corresponding threshold diameter for Earth-crossing asteroids or comets is between 1 and 2 km. Smaller objects (down to 100 m) can cause. severe local damage but pose no global threat; below 100 m most projectiles disintegrate high in the atmosphere. Current technology permits us to discover and track nearly all Earth-crossing asteroids or short-period comets large enough to threaten global catastrophe. As the initial step in any program to deal with this hazard, we require a long-term telescopic search that reaches stellar magnitude 22 in order to achieve nearly complete census of objects 1 km or larger. Such a program can be carried out with existing technology using an international network of six telescopes of 2-3 m aperture equipped with modern CCD. detectors and automatic signal processing capability. If any object threathens impact with the Earth during the next century or so, we can expect it to be identified with a lead time of at least several decades, sufficient to plan an international campaign to deflect or destroy it. RP MORRISON, D (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 11 EP 16 DI 10.1016/0094-5765(93)90095-E PG 6 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300003 ER PT J AU LEE, TJ KUTZER, A SCHNEIDER, WC AF LEE, TJ KUTZER, A SCHNEIDER, WC TI SOME THOUGHTS ON THE MANAGEMENT OF LARGE, COMPLEX INTERNATIONAL SPACE VENTURES SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB The nations of the world have already collaborated on a number of joint space ventures of varying complexities. To name a few of the variations in management arrangements, the schemes have included the utilization of one nation's spacecraft to orbit another's experiment, the launch of another's spacecraft, the development of an offline article (such as the Spacelab), and the cooperative development of the Space Station Freedom (S.S. Freedom). Today, as the scope of the problems and solutions involved in establishing a permanently manned colony on the Moon and exploring the surface of Mars become clearer, the idea of a major sharing of the enormous tasks among the spacefaring nations seems more and mom necessary and, indeed, required. For such a major. complex project, success depends upon the management as much as it does on the technology. If the project is not organized in a logical and workable manner with clear areas of responsibility and with an agreed-to chain of command it is in as much jeopardy as it is if the resources am not available. It is vital that thought and analysis be put on this aspect of a ''Mission from Planet Earth'' early, to insure that the project is not divided into an impractical organizational structure and that agreements am not made which are unsound. As an example of the questions to be explored, the lead organization can take many forms. Clearly, there must be a recognized leader to make the many difficult programmatic decisions which will arise. The lead could be assigned to one nation; it could be assigned to a new international group; it could be assigned to a consortium; or granted to a committee. Each has implications and problems to be explored. This paper will open the discussions. It is the intent of this paper to begin the process based upon the authors' experiences in various international projects. It is to arouse interest and discussion not to select a final solution. Final solutions will depend upon capabilities, financial regards, and politics (some of the variables), and the management scheme will have to take all into account. The scheme selected must be firm, logical, and workable. RP LEE, TJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 17 EP 20 DI 10.1016/0094-5765(93)90096-F PG 4 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300004 ER PT J AU FREELAND, RE BILYEU, G AF FREELAND, RE BILYEU, G TI IN-STEP INFLATABLE ANTENNA EXPERIMENT SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB Large deployable space antennas are needed to accommodate a number of applications that include mobile communications, earth observation radiometry, active microwave sensing, space-orbiting very long baseline interferometry, and Department of Defense (DoD) space-based radar. The criteria for evaluating candidate structural concepts for essentially all the applications is the same; high deployment reliability, low cost, low weight, low launch volume, and high aperture precision. A new class of space structures, called inflatable deployable structures, have tremendous potential for completely satisfying the first four criteria and good potential for accommodating the longer wavelength applications. An inflatable deployable antenna under development by L'Garde Inc. of Tustin, California, represents such a concept. Its level of technology is mature enough to support a meaningful orbital technology experiment. The NASA Office of Aeronautics and Space Technology initiated the In-Space Technology Experiments Program (IN-STEP) specifically to sponsor the verification and/or validation of unique and innovative space technologies in the space environment. The potential of the L'Garde concept has been recognized and resulted in its selection for an IN-STEP experiment. The objective of the experiment is to (a) validate the deployment of a 14-meter, inflatable parabolic reflector structure, (b) measure the reflector surface accuracy, and (c) investigate structural damping characteristics under operational conditions. The experiment approach will be to use the NASA Spartan Spacecraft to carry the experiment on orbit. Reflector deployment will be monitored by two high-resolution video cameras. Reflector surface quality will be measured with a digital imaging radiometer. Structural damping will be based on measuring the decay of reflector structure amplitude. The experiment is being managed by the Jet Propulsion Laboratory. The experiment definition phase (Phase B) will be completed by the end of fiscal year (FY) 1992; hardware development (Phase C/D) is expected to start by early FY 1993; and launch is scheduled for 1995. The paper describes the accomplishments to date and the approach for the remainder of the experiment. RP FREELAND, RE (reprint author), JET PROP LAB,TECHNOL DEV SPACE ANTENNAS & TELESCOPES APPL MECH & TECHNOL SECT,PASADENA,CA 91109, USA. NR 0 TC 6 Z9 8 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 29 EP 40 DI 10.1016/0094-5765(93)90098-H PG 12 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300006 ER PT J AU MILLER, TJ BENNETT, GL AF MILLER, TJ BENNETT, GL TI NUCLEAR PROPULSION FOR SPACE EXPLORATION SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB Nuclear propulsion has been identified as a key technology by several groups that have studied how to implement the Space Exploration Initiative to go back to the Moon, establish human presences on Mars and explore space beyond Mars. This paper will describe the results of some of the recent studies of the application of both nuclear electric and nuclear thermal propulsion systems in space exploration. This paper will also identify some of the issues that require further study and that have a significant effect on the propulsion system design and selection. RP MILLER, TJ (reprint author), NASA,LEWIS RES CTR,NUCL PROP OFF,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 143 EP 149 DI 10.1016/0094-5765(93)90106-7 PG 7 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300014 ER PT J AU SOVEY, JS CURRAN, FM HAAG, TW PATTERSON, MJ PENCIL, EJ RAWLIN, VK SANKOVIC, JM AF SOVEY, JS CURRAN, FM HAAG, TW PATTERSON, MJ PENCIL, EJ RAWLIN, VK SANKOVIC, JM TI DEVELOPMENT OF ARCJET AND ION PROPULSION FOR SPACECRAFT STATIONKEEPING SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB Near term flight applications of arcjet and ion thruster satellite station-keeping systems as well as development activities in Europe. Japan, and the United States are reviewed. At least two arcjet and three ion propulsion flights are scheduled during the 1992-1995 period. Ground demonstration technology programs are focusing on the development of kW-class hydrazine and ammonia arcjets and xenon ion thrusters. Recent work at NASA Lewis Research Center on electric thruster and system integration technologies relating to satellite stationkeeping and repositioning will also be summarized. RP SOVEY, JS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 151 EP 164 DI 10.1016/0094-5765(93)90107-8 PG 14 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300015 ER PT J AU JOHNSON, CL BROWN, NS AF JOHNSON, CL BROWN, NS TI NEAR-TERM SEI SCIENCE MISSIONS UTILIZING AN EVOLUTIONARY LUNAR TRANSPORTATION SYSTEM SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB An evolutionary program of space science missions for the lunar surface and the transportation system concept developed to deploy diem are described. Lunar-based science systems will evolve from simple, robotic instruments such as a lunar transit telescope (LTT) to large, observatory-class instruments like a 16-meter optical telescope assembled by astronauts at a lunar base. A transportation system concept to support the Space Exploration Initiative (SEI) and the deployment of these science payloads is described. Beginning with a post-Artemis lander capability, a modular approach to lunar landers is proposed as a way to maximize commonality and to support evolving SEI transportation requirements. RP JOHNSON, CL (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, 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, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 199 EP 208 DI 10.1016/0094-5765(93)90112-A PG 10 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300020 ER PT J AU VARSI, G AF VARSI, G TI MISSION OPERATIONS TECHNOLOGY SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB In the last decade, the operation of a spacecraft after launch has emerged as a major component of the total coe of the mission. This trend is sustained by the increasing complexity, flexibility, and data gathering capability of the space assets and by their greater reliability and consequent longevity. The trend can, however. be moderated by the progressive transfer of selected functions from the ground to the spacecraft and by application, on the ground, of new technology. Advances in ground operations derive from the introduction in the mission operations environment of advanced microprocessor-based workstations in the class of a low million instructions per second and from the selective application of intelligence technology. In the last few years a number of these applications have been developed, tested in operational settings and successfully demonstrated to users. Some are now being integrated in mission operations facilities. An analysis of mission operations indicates that the key areas are: concurrent control of multiple missions; automated/interactive production of command sequences of high integrity at low cost; automated monitoring Of spacecraft health and automated aidos for fault diagnosis; automated allocation of resources; automated processing of science data; and high-fidelity, high-speed spacecraft simulation. Examples of major advances in selected areas are described. RP VARSI, G (reprint author), JET PROP LAB,SPACE AUTOMAT & ROBOT PROGRAM,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 271 EP 278 DI 10.1016/0094-5765(93)90120-L PG 8 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300028 ER PT J AU STAEHLE, RL ABRAHAM, DS CARRAWAY, JB ESPOSITO, PJ SALVO, CG TERRILE, RJ WALLACE, RA WEINSTEIN, SS AF STAEHLE, RL ABRAHAM, DS CARRAWAY, JB ESPOSITO, PJ SALVO, CG TERRILE, RJ WALLACE, RA WEINSTEIN, SS TI EXPLORATION OF PLUTO SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB Pluto is the last known planet in our Solar System awaiting spacecraft reconnaissance. In its eccentric orbit taking it 50 AU from the Sun, Pluto presently has a thin atmosphere containing methane, which is projected to ''collapse'' back to the icy planet's surface in about three decades following Pluto's 1989 perihelion pass at 30 AU. Based on ground and Earth-orbit-based observing capabilities limited by Pluto's small size and extreme distance, present top-priority scientific questions for the first mission concern Pluto and Charon's surface geology, morphology and composition, and Pluto's neutral atmosphere composition. Budgetary realities preclude a large, many-instrument flyby spacecraft, while distance and launch energy requirements preclude any but the smallest orbiter using presently available launch vehicles and propulsion techniques. A NASA-sponsored Pluto Mission Development activity began this year. Two alternative cost-constrained mission implementations are described, based on which a primary implementation will be chosen. The Pluto Fast Flyby (PFF) mission utilizes an 83 kg (dry) spacecraft launched in 1998 aboard a Titan IV(SRMU)/Centaur for an approximately 7 year direct trajectory to Pluto. Instruments described are an integrated CCD-imaging/ultraviolet spectrometer, with a possible integrated infrared spectrometer. The larger Pluto-350 spacecraft, approximately 316 kg, carries a broader instrument set, greater redundancy, and requires > 11 year flight time launching in 2001 aboard a Delta or Atlas, toward Earth and Jupiter swingbys to provide the energy to reach Pluto. Launch by Proton is under consideration. Both mission implementations store data during the brief encounter, to be played back over several months. Cost is the primary design driver of both alternatives, with major tradeoffs between spacecraft development, launch services, radioisotope thermoelectric generator procurement and launch approval, and mission operations. Significant benefits are apparent from incorporating ''microspacecraft'' technologies from Earth orbiters. RP STAEHLE, RL (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 4 Z9 4 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 289 EP 310 DI 10.1016/0094-5765(93)90122-D PG 22 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300030 ER PT J AU ONEIL, WJ AUSMAN, NE JOHNSON, TV LANDANO, MR AF ONEIL, WJ AUSMAN, NE JOHNSON, TV LANDANO, MR TI GALILEO COMPLETING VEEGA - A MIDTERM REPORT SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB In December 1992, just over three years since its October 18,1989 launch, Galileo will complete its VEEGA (Venus-Earth-Earth-Gravity Assist) mission phase. Galileo will fly by the Earth on December 8, 1992, with a closest approach altitude of 300 lan to receive the gravity assist will place it on a direct trajectory to Jupiter arriving on December 7, 1995. Galileo will be the first spacecraft to send an Atmospheric Entry Probe into Jupiter's atmosphere and the first to orbit Jupiter. Immediately after the 75-minute Probe descent mission, the Orbiter will insert itself into Jupiter orbit to perform a two-year orbital mission. A far more intensive and comprehensive investigation of Jupiter will be performed than was possible with the Voyagers. Galileo became the first spacecraft to encounter an asteroid on October 29, 1991. The observations Galileo made of Gaspra are discussed. Galileo will also make unique and exciting observations of the Earth and moon during its December 1992 gravity assist encounter. The observation plan is described. The Galileo High-Gain Antenna (HGA) deployment anomaly status is reported and future corrective actions are outlined. Low-Gain Antenna Contingency Mission that will be implemented if the HGA cannot be deployed is described. The overall performance and status of the spacecraft is discussed. In the first half of 1992, the final Galileo Jupiter satellite-gravity-assist orbital tour candidates were designed. The selected tour is described. The decision to perform the August 1993 asteroid Ida flyby option was made concomitant with the tour selection. The decision rationale is presented. RP ONEIL, WJ (reprint author), JET PROP LAB,GALILEO PROJECT,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 311 EP 329 DI 10.1016/0094-5765(93)90123-E PG 19 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300031 ER PT J AU KOHRS, R HUCKINS, E AF KOHRS, R HUCKINS, E TI SPACE STATION FREEDOM - APPROACHING THE CRITICAL DESIGN PHASE THE WORLD SPACE CONGRESS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT RP KOHRS, R (reprint author), NASA,SPACE STN FREEDOM,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 331 EP 334 PG 4 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300032 ER PT J AU AHLF, P VOLOSIN, J AF AHLF, P VOLOSIN, J TI TECHNOLOGY PLANNING FOR LONG-RANGE UTILIZATION OF SPACE STATION FREEDOM SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43RD CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION : DISCOVERY, EXPLORATION AND COOPERATION CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW, NASA, US NATL ACAD SCI, AMER INST AERONAUT & ASTRONAUT AB Over the course of the operational life of Space Station Freedom (SSF), technologies used for spacecraft design and use will advance. In some cases, such as data management, components or systems initially incorporated in the design may become obsolete in a relatively short period of time. In order to assure that SSF can benefit from new technologies, beneficial technologies must be identified, development of beneficial technologies must be tracked and advocated where appropriate, the design must accommodate technology upgrades, and a process for transferring technologies into the flight program must be implemented. The NASA Office of Space Flight, in coordination with the SSF program, has developed a consolidated listing of high priority technology requirements in support of overall Agency technology development planning. Included in this list are technologies which support increased utilization of SSF, enhance crew safety or productivity, or reduce operations costs. Efforts to ensure development of these technologies have begun, and a mechanism for technology transfer has been developed. RP AHLF, P (reprint author), NASA,HEADQUARTERS,OFF SPACE SYST DEV,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 30 BP 345 EP 356 DI 10.1016/0094-5765(93)90126-H PG 12 WC Engineering, Aerospace SC Engineering GA LQ343 UT WOS:A1993LQ34300034 ER PT J AU FREELAND, RE JOHNSTON, RD AF FREELAND, RE JOHNSTON, RD TI DEVELOPMENT OF STRUCTURAL COMPOSITE MIRROR TECHNOLOGY FOR SUBMILLIMETER SPACE TELESCOPES SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB Lightweight, low-cost, high-precision mirrors are needed to support a number of near-term and far-term submillimeter, space-based astronomical telescopes. These telescopes will range in size from 3 to 20 m, and will possibly be larger. They will utilize mirrors varying from 1 to 2 m in size and from 1 to 3 mum rms in surface precision; they will operate in an orbital thermal environment somewhere between 100 and 200 K. The Precision Segmented Reflector (PSR) program, sponsored by the NASA Office of Aeronautics, Exploration and Technology (OAET), was formulated and implemented specifically to develop the telescope technologies associated with future NASA missions. A major element of that program is the development of lightweight structural composite mirrors, which is the subject of this paper. The most significant technology challenges associated with the development of these highly specialized mirrors are (a) the processing and manufacturing required to produce high-precision. lightweight mirrors and (b) the determination of materials and structural mirror configurations that produce the thermal stability needed for specific classes of applications. These challenges have been addressed by a joint partnership between the Jet Propulsion Laboratory (JPL) and the Hexcel Corporation during the 4-year PSR program. This paper describes the technical approach used for the design, manufacturing, testing, and analytical simulation of lightweight graphite/epoxy mirrors. This program has produced (a) 1.0 m graphite/epoxy panels with areal densities of 7 kg/m2 and as-manufactured surface precision near 1 mum rms. (b) 0.5 m panels with figure changes of < 1 mum rms for temperature reductions of 100 K, (c) analytical performance-prediction capability with submicron accuracy relative to panel thermal distortion, and (d) a unique thermal vacuum test facility for structural composite mirrors. RP FREELAND, RE (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 29 IS 7 BP 537 EP 545 DI 10.1016/0094-5765(93)90058-5 PG 9 WC Engineering, Aerospace SC Engineering GA LJ374 UT WOS:A1993LJ37400005 ER PT J AU MILLER, DP VARSI, G AF MILLER, DP VARSI, G TI MICROTECHNOLOGY FOR PLANETARY EXPLORATION AND EDUCATION SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB Recent work has shown that it is possible to build small robots (typically almost-equal-to 10 kg) that are capable of safely navigating through rough, slightly hazardous terrain. Companion developments in micro-sensors and micro-instrumentation have recently been proposed and, in some cases, demonstrated at the level of proof-of-concept. Micro-robots, therefore, when given an agile mobility system, a power supply, and a complement of micro-instruments are capable of performing useful scientific analysis. Since the rovers are small, they can have a greater strength to weight ratio, and can therefore accept a higher landing shock. Many small rovers conducting exploration in parallel yield three key advantages: first, coverage of a large area, if the rovers are landed at different locations; second, reliability through redundancy, thus offering the capability to explore sites that are scientifically interesting, but potentially of high hazard; third, opportunities for a large group of investigators to participate in the early exploratory surveys, if command of separate groups of micro-rovers is distributed among independent investigators. It is particularly intriguing to offer a fraction of the micro-rover fleet for a limited amount of time to teams of students, guided by their instructors. Such a program would: (1) explore a new mission architecture which reflects the powerful advantages of distributed processes and (2) welcome a new resourceful segment of the population into space science and exploration. RP MILLER, DP (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1993 VL 29 IS 7 BP 561 EP 567 DI 10.1016/0094-5765(93)90061-Z PG 7 WC Engineering, Aerospace SC Engineering GA LJ374 UT WOS:A1993LJ37400008 ER PT J AU CLARK, JS MCILWAIN, MC SMETANIKOV, V DYAKOV, EK PAVSHOOK, VA AF CLARK, JS MCILWAIN, MC SMETANIKOV, V DYAKOV, EK PAVSHOOK, VA TI UNITED-STATES CIS EYE JOINT NUCLEAR ROCKET VENTURE SO AEROSPACE AMERICA LA English DT Article RP CLARK, JS (reprint author), NASA,LEWIS RES CTR,NUCL PROPULS OFF,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1993 VL 31 IS 7 BP 28 EP & PG 0 WC Engineering, Aerospace SC Engineering GA LJ674 UT WOS:A1993LJ67400010 ER PT J AU YANG, Z SHIH, TH AF YANG, Z SHIH, TH TI NEW TIME-SCALE BASED KAPPA-EPSILON-MODEL FOR NEAR-WALL TURBULENCE SO AIAA JOURNAL LA English DT Article ID REYNOLDS-NUMBER TURBULENCE; BOUNDARY-LAYER; FLOWS AB A k-epsilon model is proposed for wall-bounded turbulent flows. In this model, the eddy viscosity is characterized by a turbulent velocity scale and a turbulent time scale. The time scale is bounded from below by the Kolmogorov time scale. The dissipation equation is reformulated using this time scale, and no singularity exists at the wall. The damping function used in the eddy viscosity is chosen to be a function of R(y) = (k1/2y/nu) instead of y+, as in the Lam and Bremhorst model. Hence, the model could be used for flows with separation. The model constants used are the same as in the high Reynolds number standard k-epsilon model. Thus, the proposed model will also be suitable for flows far from the wall. Turbulent channel flows al different Reynolds numbers and turbulent boundary-layer flows with and without pressure gradient are calculated. Results show that the model predictions are in good agreement with direct numerical simulation and experimental data. RP YANG, Z (reprint author), NASA,LEWIS RES CTR,CTR MODELING TURBULENCE & TRANSIT,INST COMPUTAT MECH PROP,CLEVELAND,OH 44135, USA. NR 18 TC 165 Z9 172 U1 0 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1993 VL 31 IS 7 BP 1191 EP 1198 DI 10.2514/3.11752 PG 8 WC Engineering, Aerospace SC Engineering GA LM761 UT WOS:A1993LM76100004 ER PT J AU WEINSTEIN, LM AF WEINSTEIN, LM TI LARGE-FIELD HIGH-BRIGHTNESS FOCUSING SCHLIEREN SYSTEM SO AIAA JOURNAL LA English DT Article AB The analysis and performance of a large-field high-brightness focusing schlieren system is described. Techniques are described that allow the system to be used even through slightly distorting optical elements. The system can be used to examine complex two- and three-dimensional flows. RP WEINSTEIN, LM (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,EXPTL METHODS BRANCH,HAMPTON,VA 23665, USA. NR 12 TC 21 Z9 22 U1 1 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1993 VL 31 IS 7 BP 1250 EP 1255 DI 10.2514/3.11760 PG 6 WC Engineering, Aerospace SC Engineering GA LM761 UT WOS:A1993LM76100012 ER PT J AU BASHOUR, TT MANSOUR, NN LEE, D AF BASHOUR, TT MANSOUR, NN LEE, D TI MULTIPLE CORONARY ARTERIAL LOOPS AS A CAUSE OF MYOCARDIAL-ISCHEMIA SO AMERICAN HEART JOURNAL LA English DT Note C1 SETON HOSP,SAN FRANCISCO HEART INST,SAN FRANCISCO,CA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BASHOUR, TT (reprint author), ST MARYS HOSP,WESTERN HEART INST,450 STANYAN ST,SAN FRANCISCO,CA 94117, USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU MOSBY-YEAR BOOK INC PI ST LOUIS PA 11830 WESTLINE INDUSTRIAL DR, ST LOUIS, MO 63146-3318 SN 0002-8703 J9 AM HEART J JI Am. Heart J. PD JUL PY 1993 VL 126 IS 1 BP 219 EP 221 DI 10.1016/S0002-8703(07)80032-9 PG 3 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA LL210 UT WOS:A1993LL21000030 PM 8322668 ER PT J AU NEMIROFF, RJ AF NEMIROFF, RJ TI VISUAL DISTORTIONS NEAR A NEUTRON-STAR AND BLACK-HOLE SO AMERICAN JOURNAL OF PHYSICS LA English DT Article ID GENERAL-RELATIVITY; SKY AB The visual distortion effects visible to an observer traveling around and descending to the surface of an extremely compact star are described. Specifically, trips to a ''normal'' neutron star, a black hole, and an ultracompact neutron star with extremely high surface gravity, are described. Concepts such as multiple imaging, red- and blue-shifting, conservation of surface brightness, the photon sphere, and the existence of multiple Einstein rings are discussed in terms of what the viewer would see. Computer generated, general relativistically accurate illustrations highlighting the distortion effects are presented and discussed. A short movie (VHS) depicting many of these effects is available to those interested free of charge. RP NEMIROFF, RJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 6681,GREENBELT,MD 20771, USA. NR 35 TC 53 Z9 53 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0002-9505 J9 AM J PHYS JI Am. J. Phys. PD JUL PY 1993 VL 61 IS 7 BP 619 EP 632 DI 10.1119/1.17224 PG 14 WC Education, Scientific Disciplines; Physics, Multidisciplinary SC Education & Educational Research; Physics GA LJ662 UT WOS:A1993LJ66200008 ER PT J AU VERNIKOS, J DALLMAN, MF KEIL, LC OHARA, D CONVERTINO, VA AF VERNIKOS, J DALLMAN, MF KEIL, LC OHARA, D CONVERTINO, VA TI GENDER DIFFERENCES IN ENDOCRINE RESPONSES TO POSTURE AND 7 DAYS OF -6-DEGREES HEAD-DOWN BED REST SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE PLASMA RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM; SODIUM BALANCE; PLASMA VOLUME; PITUITARY-ADRENAL SEX DIFFERENCES ID ATRIAL NATRIURETIC PEPTIDE; OUT IMMERSION; REDUCTION; VOLUME; HUMANS; STRESS; NIGHT AB Endocrine regulation of fluids and electrolytes during 7 days of -6-degrees head-down bed rest (HDBR) was compared in male (n = 8) and, for the first time, female (n = 8) volunteers. The subjects' responses to quiet standing for 2 h before and after HDBR were also tested. In both sexes, diuresis and natriuresis were evident during the first 2-3 days of HDBR, resulting in a marked increase in the urinary Na+-to-K+ ratio and significant Na+ retention on re-ambulation. After the lst day of HDBR, plasma renin activity (PRA) was increased relative to aldosterone (Aldo), plasma volume was decreased, and the renal response to Aldo appeared to be appropriate. Circulating levels of arginine vasopressin, cortisol, and ACTH were unchanged during HDBR. Plasma testosterone decreased slightly on day 2 of HDBR in males. The ratio of early morning ACTH to cortisol was lower in females than in males because ACTH was lower in females. Urinary cortisol increased and remained elevated throughout the HDBR in males only. There were no gender differences in the responses to 7 days of HDBR, except those in the pituitary-adrenal system; those differences appeared unrelated to the postural change. The provocative cardiovascular test of quiet standing before and after HDBR revealed both sex differences and effects of HDBR. There were significant sex differences in cardiovascular responses to standing before and after HDBR. Females had greater PRA and Aldo responses to standing before HDBR and larger Aldo responses to standing after HDBR than males. Cardiovascular responses to standing before and after HDBR differed markedly; arterial pressure and heart rates increased with standing before HDBR; by contrast, after HDBR, arterial pressure decreased, with greater increases in heart rates. In both sexes, all hormonal responses to standing were greater after HDBR. The results show clearly that similar responses to standing and HDBR occur in both sexes but that females exhibit greater PRA and Aldo responses than males. C1 UNIV CALIF SAN FRANCISCO,DEPT PHYSIOL,SAN FRANCISCO,CA 94143. ARMSTRONG LAB,SAN ANTONIO,TX 78235. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 27 TC 40 Z9 41 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD JUL PY 1993 VL 265 IS 1 BP E153 EP E161 PN 1 PG 9 WC Physiology SC Physiology GA LP431 UT WOS:A1993LP43100060 PM 8338147 ER PT J AU ODONNELL, CP KEIL, LC THRASHER, TN AF ODONNELL, CP KEIL, LC THRASHER, TN TI VASOPRESSIN, RENIN, AND CORTISOL RESPONSES TO HEMORRHAGE DURING ACUTE BLOCKADE OF CARDIAC NERVES IN CONSCIOUS DOGS SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE BLOOD PRESSURE; BARORECEPTORS; CARDIAC RECEPTORS; ANTIDIURETIC HORMONE; ADRENOCORTICOTROPIC HORMONE; ANGIOTENSIN ID ARGININE VASOPRESSIN; PLASMA VASOPRESSIN; ARTERIAL BARORECEPTORS; RELEASE; RECEPTORS; HYPOTENSION; INHIBITION; MECHANISM; SECRETION; PRESSURE AB The effect of acute cardiac nerve blockade (CNB) on the increases in plasma renin activity (PRA), arginine vasopressin (AVP), and cortisol in response to a 30 ml/kg hemorrhage was determined in conscious dogs (n = 9). Procaine was infused into the pericardial space to produce acute reversible CNB, or saline was infused in the control hemorrhage. Blood was removed from the inferior vena cava at a rate of 1 ml.kg-1.min-1. In the control hemorrhage, plasma AVP increased from 1.8 +/- 0.3 to 219 +/- 66 pg/ml, PRA increased from 0.63 +/- 0.20 to 3.08 +/- 0.91 ng angiotensin I (ANG I).ml-1.3 h-1, and cortisol increased from 1.4 +/- 0.2 to 4.0 +/- 0.7 mug/dl. When the hemorrhage was repeated during acute CNB, plasma AVP increased from 2.8 +/- 1.6 to 185 +/- 59 pg/ml, PRA increased from 0.44 +/- 0.14 to 2.24 +/- 0.27 ng ANG I.ml-1.3 h-1, and cortisol increased from 1.9 +/- 0.3 to 5.4 +/- 0.6 mug/dl, and none of the increases differed significantly from the responses during the control hemorrhage. Left atrial pressure fell significantly after removal of 6 ml/kg of blood, but mean arterial pressure was maintained at control levels until blood loss reached 20 ml/kg during pericardial infusion of either saline or procaine. The declines in MAP at the 30 ml/kg level of hemorrhage in both treatments were similar. These results demonstrate that acutely blocking input from cardiac receptors does not reduce the increases in plasma AVP, cortisol, and PRA in response to a 30 ml/kg hemorrhage. The results of this study do not support the hypothesis that input from cardiac receptors is required for a normal AVP response to hemorrhage and suggest that other receptors, presumably arterial baroreceptors, can stimulate AVP and cortisol secretion in the absence of signals from the heart. C1 UNIV CALIF SAN FRANCISCO,SCH MED,DEPT PHYSIOL,BOX 0444,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. FU NHLBI NIH HHS [HL-41313] NR 40 TC 17 Z9 17 U1 1 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD JUL PY 1993 VL 265 IS 1 BP R220 EP R229 PN 2 PG 10 WC Physiology SC Physiology GA LP432 UT WOS:A1993LP43200091 PM 8342691 ER PT J AU EICEMAN, GA SALAZAR, MR RODRIGUEZ, MR LIMERO, TF BECK, SW CROSS, JH YOUNG, R JAMES, JT AF EICEMAN, GA SALAZAR, MR RODRIGUEZ, MR LIMERO, TF BECK, SW CROSS, JH YOUNG, R JAMES, JT TI ION MOBILITY SPECTROMETRY OF HYDRAZINE, MONOMETHYLHYDRAZINE, AND AMMONIA IN AIR WITH 5-NONANONE REAGENT GAS SO ANALYTICAL CHEMISTRY LA English DT Article ID PLASMA CHROMATOGRAPHY; H2O AB Hydrazine (HZ) and monomethylhydrazine (MMH) in air were monitored continuously using a hand-held ion mobility spectrometer equipped with membrane inlet, Ni-63 ion source, acetone reagent gas, and ambient temperature drift tube. Response characteristics included detection limit, 6 ppb; linear range, 10-600 ppb; saturated response, >2 ppm; and stable response after 15-30 min. Ammonia interfered in hydrazines detection through a product ion with the same drift time as that for MMH and HZ. Acetone reagent gas was replaced with 5-nonanone to alter drift times of product ions and separate ammonia from MMH and HZ. Patterns in mobility spectra, ion identifications from mass spectra, and fragmentation cross-sections from collisional-induced dissociations suggest that drift times are governed by ion-cluster equilibria in the drift region of the mobility spectrometer. Practical aspects including calibration, stability, and reproducibility are reported from the use of a hand-held mobility spectrometer on the space shuttle Atlantis during mission STS-37. C1 KRUG LIFE SCI INC,HOUSTON,TX 77058. NASA,TOX VAPOR DETECT LAB,KENNEDY SPACE CTR,FL 32899. NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,HOUSTON,TX 77058. RP EICEMAN, GA (reprint author), NEW MEXICO STATE UNIV,DEPT CHEM,LAS CRUCES,NM 88003, USA. NR 22 TC 47 Z9 48 U1 2 U2 10 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0003-2700 J9 ANAL CHEM JI Anal. Chem. PD JUL 1 PY 1993 VL 65 IS 13 BP 1696 EP 1702 DI 10.1021/ac00061a011 PG 7 WC Chemistry, Analytical SC Chemistry GA LJ380 UT WOS:A1993LJ38000013 PM 11537896 ER PT J AU MONTGOMERY, LD PARMET, AJ BOOHER, CR AF MONTGOMERY, LD PARMET, AJ BOOHER, CR TI BODY VOLUME CHANGES DURING SIMULATED MICROGRAVITY - AUDITORY CHANGES, SEGMENTAL FLUID REDISTRIBUTION, AND REGIONAL HEMODYNAMICS SO ANNALS OF BIOMEDICAL ENGINEERING LA English DT Article DE BED REST; MICROGRAVITY; FLUID REDISTRIBUTION; AUDIOMETRY ID MOTION SICKNESS; IMPEDANCE; PLETHYSMOGRAPHY; LIMB; PRESSURE AB Space adaptation syndrome (SAS), manifested by cephalad fluid shifts, spacial disorientation, nausea, and vomiting, is of varied expression and uncertain etiology. One theory is that fluid shift to the upper body alters the function of the vestibular apparatus to create an entity similar to Meniere's disease. Since clinical vestibular dysfunction syndromes are mirrored by altered cochlear function, this experiment was undertaken to study the relation between fluid redistribution and the auditory effects of initial antiorthostatic bed rest. Manual and bone audiometry, impedance tympanometry, and brain-stem evoked potentials were used to monitor auditory changes prior to, during, and following short term exposure to -6-degrees head down tilt. Impedance plethysmography was performed to assess the segmental and intracranial fluid redistribution and hemodynamic changes during short-term head down tilt simulated microgravity. Even though significant cephalad fluid shift produced marked intracranial congestion and the subjects exhibited SAS symptoms, no clinically significant changes in the auditory system could be detected. C1 LDM ASSOCIATES,SAN JOSE,CA. USAF,SCH AEROSP MED,BROOKS AFB,TX. ST LUKES OCCUPAT & AVIAT MED,KANSAS CITY,MO. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NASA,WASHINGTON,DC 20546. NR 45 TC 20 Z9 20 U1 0 U2 5 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0090-6964 J9 ANN BIOMED ENG JI Ann. Biomed. Eng. PD JUL-AUG PY 1993 VL 21 IS 4 BP 417 EP 433 DI 10.1007/BF02368634 PG 17 WC Engineering, Biomedical SC Engineering GA LP307 UT WOS:A1993LP30700011 PM 8214826 ER PT J AU SIMON, HD DAGUM, L AF SIMON, HD DAGUM, L TI EXPERIENCE IN USING SIMD AND MIMD PARALLELISM FOR COMPUTATIONAL FLUID-DYNAMICS SO APPLIED NUMERICAL MATHEMATICS LA English DT Article; Proceedings Paper CT 13TH WORLD CONGRESS OF THE INTERNATIONAL ASSOC FOR MATHEMATICS AND COMPUTERS IN SIMULATION : COMPUTATION AND APPLIED MATHEMATICS CY JUL 22-26, 1991 CL DUBLIN, IRELAND SP INT ASSOC MATH & COMP SIMULAT DE PARALLEL ARCHITECTURES; MIMD; SIMD; COMPUTATIONAL FLUID DYNAMICS AB One of the key objectives of the Applied Research Branch in the Numerical Aerodynamic Simulation (NAS) Systems Division at NASA Ames Research Center is the accelerated introduction of highly parallel machines into a fully operational environment. In this report we summarize some of the experiences with the parallel testbed machines at the NAS Applied Research Branch. We discuss the performance results obtained from the implementation of two computational fluid dynamics (CFD) applications, an unstructured grid solver and a particle simulation, on the Connection Machine CM-2 and the Intel iPSC/860. RP SIMON, HD (reprint author), NASA,AMES RES CTR,DIV NUMER AERODYNAM SIMULAT SYST,APPL RES BRANCH,MAIL STOP T045-1,MOFFETT FIELD,CA 94035, USA. NR 28 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9274 J9 APPL NUMER MATH JI Appl. Numer. Math. PD JUL PY 1993 VL 12 IS 5 BP 431 EP 442 DI 10.1016/0168-9274(93)90103-X PG 12 WC Mathematics, Applied SC Mathematics GA LR147 UT WOS:A1993LR14700006 ER PT J AU CONNOLLY, DJ ROMANOFSKY, RR ARON, P STAN, M AF CONNOLLY, DJ ROMANOFSKY, RR ARON, P STAN, M TI OPPORTUNITIES FOR SUPERCONDUCTIVITY IN FUTURE SPACE EXPLORATION PROGRAMS - (A HYDROGEN ECONOMY FOR THE 21ST-CENTURY) SO APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF AND EXHIBITION ON WORLD CONGRESS ON SUPERCONDUCTIVITY CY SEP 15-18, 1992 CL MUNICH, GERMANY ID JUNCTIONS; SQUIDS AB Since the discovery of the 90K materials about five years ago the progress in development of thin film superconducting materials for microwave applications has progressed rapidly. At this point high temperature superconducting (HTS) films are already good enough for most space microwave applications. And a large community of technology developers are participating in insertion of this technology largely under the leadership of NRL's HTSSE program. A review of this area is contained in a companion paper by Leonard et. al. The progress in developing bulk superconductor technology, which is the basis of most large scale applications of HTS, has been steady but has not led to the perception that HTS materials are anywhere near ready for these applications. in the Space Exploration Initiative and generally in the long term we feel that the large payoff will be in the large scale applications of HTS not in thin film microwave applications. Interesting opportunities exist, for large scale bulk and digital applications of superconductivity in space, if one considers the possibilities for liquid hydrogen cooled superconducting systems operating near 20K. RP CONNOLLY, DJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 36 TC 0 Z9 0 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD JUL-SEP PY 1993 VL 1 IS 7-9 BP 1231 EP 1249 DI 10.1016/0964-1807(93)90432-2 PG 19 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA LG392 UT WOS:A1993LG39200040 ER PT J AU CARLBERG, IA KELLIHER, WC WISE, SA HOOKER, MW BUCKLEY, JD AF CARLBERG, IA KELLIHER, WC WISE, SA HOOKER, MW BUCKLEY, JD TI ENVIRONMENTAL CONSIDERATIONS FOR APPLICATION OF HIGH-TC SUPERCONDUCTORS IN SPACE SO APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF AND EXHIBITION ON WORLD CONGRESS ON SUPERCONDUCTIVITY CY SEP 15-18, 1992 CL MUNICH, GERMANY ID GAMMA-IRRADIATION; YBA2CU3O7-X; WATER; PHASE AB High temperature superconductive materials can have significant impact in several space-based applications due to the improved electrical, magnetic, or thermal properties of the superconductive devices over existing components. However, for high temperature superconductors to be successfully applied in space-borne systems, several environmental considerations associated with spaceflight must first be addressed. The environmental factors encountered during spaceflight missions will be discussed, and a review of studies addressing the effects of these factors on the performance of the superconductive devices will be provided. RP CARLBERG, IA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 24 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD JUL-SEP PY 1993 VL 1 IS 7-9 BP 1251 EP 1258 DI 10.1016/0964-1807(93)90433-3 PG 8 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA LG392 UT WOS:A1993LG39200041 ER PT J AU DECHER, R PETERS, PN SISK, RC URBAN, EW VLASSE, M RAO, DK AF DECHER, R PETERS, PN SISK, RC URBAN, EW VLASSE, M RAO, DK TI HIGH-TEMPERATURE SUPERCONDUCTING BEARING FOR ROCKET ENGINE TURBOPUMPS SO APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF AND EXHIBITION ON WORLD CONGRESS ON SUPERCONDUCTIVITY CY SEP 15-18, 1992 CL MUNICH, GERMANY ID MAGNETIC BEARINGS; LEVITATION AB High temperature superconductor (HTS) magnetic bearings offer many advantages. Their applications are most promising in systems which provide the necessary cryogenic environment. The hydrogen turbopump of a nuclear propulsion engine is such a system. The combination of an HTS bearing and a fluid film bearing could over-come problems experienced with rolling element bearings in rocket engine turbo pumps. C1 MECH TECHNOL INC,LATHAM,NY 12110. RP DECHER, R (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 14 TC 27 Z9 29 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD JUL-SEP PY 1993 VL 1 IS 7-9 BP 1265 EP 1278 DI 10.1016/0964-1807(93)90435-5 PG 14 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA LG392 UT WOS:A1993LG39200043 ER PT J AU HOOKER, MW TAYLOR, TD LEIGH, HD WISE, SA BUCKLEY, JD VASQUEZ, P BUCK, GM HICKS, LP AF HOOKER, MW TAYLOR, TD LEIGH, HD WISE, SA BUCKLEY, JD VASQUEZ, P BUCK, GM HICKS, LP TI NONAQUEOUS SLIP CASTING OF YBA2CU3O7-X CERAMICS SO APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF AND EXHIBITION ON WORLD CONGRESS ON SUPERCONDUCTIVITY CY SEP 15-18, 1992 CL MUNICH, GERMANY ID SUPERCONDUCTING PROPERTIES; SAMPLES AB A ceramic casting process based on the fundamentals of slip casting has been developed to form high Tc superconductive ceramics. In this process, YBa2Cu3O7-x Powders (<20mum) dispersed in acetone are cast into foundry molds prepared by a lost wax process. After casting, the mold is peeled away from the superconductor, yielding a ceramic monolith in the shape of the mold. This work describes the casting process, as well as the results of a preliminary investigation into the use of magnetic fields to orient the YBa2Cu3O7-x grains during the forming process. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HOOKER, MW (reprint author), CLEMSON UNIV,DEPT CERAM ENGN,CLEMSON,SC 29634, USA. NR 16 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD JUL-SEP PY 1993 VL 1 IS 7-9 BP 1303 EP 1311 DI 10.1016/0964-1807(93)90438-8 PG 9 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA LG392 UT WOS:A1993LG39200046 ER PT J AU LEONARD, RF BHASIN, KB ROMANOFSKY, RR CUBBAGE, CD CHOREY, CZ AF LEONARD, RF BHASIN, KB ROMANOFSKY, RR CUBBAGE, CD CHOREY, CZ TI SPACE APPLICATIONS OF SUPERCONDUCTING MICROWAVE ELECTRONICS AT NASA LEWIS RESEARCH-CENTER SO APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF AND EXHIBITION ON WORLD CONGRESS ON SUPERCONDUCTIVITY CY SEP 15-18, 1992 CL MUNICH, GERMANY AB Since the discovery of high temperature superconductivity in 1987, NASA Lewis Research Center has been involved in efforts to demonstrate its advantages for applications involving microwave electronics in space, especially space communications. The program has included thin film fabrication by means of laser ablation. Specific circuitry which has been investigated includes microstrip ring resonators at 32 GHz, phase shifters which utilize a superconducting, optically activated switch, an 8x8 32 GHz superconducting microstrip antenna array, and an HTS-ring-resonator stabilized oscillator at 8 GHz. The latter two components are candidates for use in space experiments which will be described in other papers. Experimental data on most of the circuits will be presented as well as, in some cases, a comparison of their performance with an identical circuit utilizing gold or copper metallization. C1 SVERDRUP CORP,CLEVELAND,OH. RP LEONARD, RF (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD JUL-SEP PY 1993 VL 1 IS 7-9 BP 1341 EP 1347 PG 7 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA LG392 UT WOS:A1993LG39200049 ER PT J AU NGO, P KRISHEN, K ARNDT, D RAFFOUL, G KARASAK, V BHASIN, K LEONARD, R AF NGO, P KRISHEN, K ARNDT, D RAFFOUL, G KARASAK, V BHASIN, K LEONARD, R TI A HIGH-TEMPERATURE SUPERCONDUCTIVITY COMMUNICATIONS FLIGHT EXPERIMENT SO APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF AND EXHIBITION ON WORLD CONGRESS ON SUPERCONDUCTIVITY CY SEP 15-18, 1992 CL MUNICH, GERMANY AB A high-temperature superconductivity (HTSC) flight experiment from the payload bay of the Space Shuttle Orbiter to the Advanced Communications Technology Satellite (ACTS) is being breadboarded. This proposed experiment, a joint project between the Johnson Space Center and the Lewis Research Center, would use a Ka-band (20 GHz) HTSC phased array antenna and front-end electronics (low-noise amplifier) to receive a downlink communications signal from the ACTS. A conventional receiver demodulates the encoded telemetry signal which is then turned around and transmitted back to ACTS and die ground. The HTSC phased array has nine 4 x 4 microstrip patch antenna subarrays which when properly phased, provide approximately 24 dB of boresight gain. A 2 x 2 HTSC microstrip patch has been built and tested. A Ka-band receiver, transmitter, modem, encoder, decoder, etc., are now being built and tested. Link analyses and interface problems with the Orbiter are addressed in the paper in addition to the design, fabrication, and testing of various subsystems used in the communication link. C1 LOCKHEED,HOUSTON,TX. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP NGO, P (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD JUL-SEP PY 1993 VL 1 IS 7-9 BP 1349 EP 1361 DI 10.1016/0964-1807(93)90442-5 PG 13 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA LG392 UT WOS:A1993LG39200050 ER PT J AU WISE, SA BUCKLEY, JD NOLT, I HOOKER, MW HAERTLING, GH SELIM, R CATON, R BUONCRISTIANI, AM AF WISE, SA BUCKLEY, JD NOLT, I HOOKER, MW HAERTLING, GH SELIM, R CATON, R BUONCRISTIANI, AM TI HIGH-TC THERMAL BRIDGES FOR SPACE-BORNE CRYOGENIC INFRARED DETECTORS SO APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF AND EXHIBITION ON WORLD CONGRESS ON SUPERCONDUCTIVITY CY SEP 15-18, 1992 CL MUNICH, GERMANY ID FILMS; SUPERCONDUCTIVITY AB Several space-borne infrared detectors require cryogenic temperatures for successful operation. As a result, mission durations are substantially limited due to cryogen evaporation. The electrical leads connecting the detectors to the amplification electronics comprise a significant portion of the heat load on the dewar (i.e., 20% for some systems). Currently, manganin wires are used for these connections, due to the alloy's low thermal conductivity at cryogenic temperatures. However, replacement of these leads with high Tc materials would result in a substantial reduction in thermal loss, translating into approximately 10- 15 % enhancement in mission lifetime. The potential for using the high-Tc materials as thermal bridges to replace the manganin connections is currently under investigation at NASA-LaRC. C1 CLEMSON UNIV,DEPT CERAM ENGN,CLEMSON,SC 29631. CHRISTOPHER NEWPORT COLL,DEPT PHYS & COMP SCI,NEWPORT NEWS,VA. RP WISE, SA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 20 TC 5 Z9 5 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD JUL-SEP PY 1993 VL 1 IS 7-9 BP 1363 EP 1372 DI 10.1016/0964-1807(93)90443-6 PG 10 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA LG392 UT WOS:A1993LG39200051 ER PT J AU DAMM, G MIZUGUCHI, K BOZEMAN, R AKKERMAN, J ABER, G SVEJKOVSKY, P TAKATANI, S NOSE, Y NOON, GP DEBAKEY, ME AF DAMM, G MIZUGUCHI, K BOZEMAN, R AKKERMAN, J ABER, G SVEJKOVSKY, P TAKATANI, S NOSE, Y NOON, GP DEBAKEY, ME TI INVITRO PERFORMANCE OF THE BAYLOR NASA AXIAL-FLOW PUMP SO ARTIFICIAL ORGANS LA English DT Article; Proceedings Paper CT INTERNATIONAL SYMP ON THE ROTARY BLOOD PUMP : THE 2ND-GENERATION CARDIO-PULMONARY BYPASS PUMP AND BEYOND CY NOV 14-15, 1992 CL TEXAS MED CTR, HOUSTON, TX HO TEXAS MED CTR DE AXIAL FLOW PUMP; LEFT VENTRICULAR ASSIST DEVICE; HEMOLYSIS; TEST MATRIX AB A cooperative effort between Baylor College of Medicine and NASA/Johnson Space Center is under way to develop an implantable axial flow left ventricular assist device (LVAD). The pump is intended as an assist device for either pulmonary or systemic circulatory support for more than 3 months' duration. Currently, in vitro studies are under way to reduce the hemolysis generated by the axial flow pump. A system utilizing a testing matrix has been developed to analyze the effects of different pump parameters on hemolysis. The following parameters are being investigated: impeller blade tip geometry, impeller/flow tube clearance, impeller/stator clearance, number of impeller blades, number of stator blades, and length of the impeller. To date, an index of hemolysis of 0.038 g/100 L has been achieved. The test matrix is not complete, and further improvements are expected. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP DAMM, G (reprint author), BAYLOR COLL MED,DEPT SURG,1 BAYLOR PLAZA,HOUSTON,TX 77030, USA. NR 3 TC 17 Z9 20 U1 0 U2 1 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0160-564X J9 ARTIF ORGANS JI Artif. Organs PD JUL PY 1993 VL 17 IS 7 BP 609 EP 613 PG 5 WC Engineering, Biomedical; Transplantation SC Engineering; Transplantation GA LH826 UT WOS:A1993LH82600007 PM 8338435 ER PT J AU LEE, MG MADORE, BF AF LEE, MG MADORE, BF TI BVRI CCD PHOTOMETRY OF THE RESOLVED GALAXY NGC-1560 SO ASTRONOMICAL JOURNAL LA English DT Article ID NEARBY GALAXIES; BRIGHTEST STARS; STELLAR CONTENT; EXTINCTION AB We present BVRI CCD photometry of approximately 600 stars in the central region of a resolved spiral galaxy NGC 1560 which is seen almost edge-on, apparently located in the IC 342 group. The V - (B - V) diagram shows a dominant group of significantly reddened blue plume stars consisting of young massive main-sequence and evolved blue supergiant stars. The tip of the blue plume is found to be at V approximately 21 mag and (B - V) approximately 0.4 mag. The I - (R - I) diagram shows a large group of red supergiants the brightest of which are extending to I approximately 19.5 mag at (R - I) approximately 1.1 mag. The logarithmic slope of the V luminosity function of the blue plume stars is 0.69 +/- 0. 10, similar to that for other nearby galaxies. The mean color of the blue plume stars is [(B - V)] = 0.25 +/- 0.03 mag. The total reddening, including both foreground and internal reddening, is estimated from the mean color of the blue plume stars, to be E(B - V) = 0.40 +/- 0.10 mag, whereas the foreground reddening based on the H I column density and faint galaxy counts is E( B - V) = 0.16 mag. Combining our results with those in the literature, we have obtained distance estimates using four methods: brightest blue stars [(m-M)0 = 27.11 mag], brightest red stars [(m-M)0 = 27.02 mag], B-band Tully-Fisher relation [(m-M)0 = 26.96 mag], and H-band Tully-Fisher relation [(m-M)0 = 26.86 mag]. These four estimates agree very well. Taking the average of these four estimates, we obtain a value for the true distance modulus to NGC 1560, (m - M)0 = 27.0 +/- 0.1 mag, corresponding to a distance of 2.5 +/- 0.1 Mpc. C1 CALTECH,JET PROP LAB,NASA,IPAC EXTRAGALACT DATABASE,CTR INFRARED PROC & ANAL,PASADENA,CA 91101. RP LEE, MG (reprint author), CARNEGIE INST WASHINGTON OBSERV,813 SANTA BARBARA ST,PASADENA,CA 91101, USA. NR 26 TC 8 Z9 8 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1993 VL 106 IS 1 BP 66 EP 79 DI 10.1086/116621 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ882 UT WOS:A1993LJ88200008 ER PT J AU KEEL, WC WEHRLE, AE AF KEEL, WC WEHRLE, AE TI THE DYNAMIC INTERSTELLAR-MEDIUM IN NGC-4438 SO ASTRONOMICAL JOURNAL LA English DT Article ID SPIRAL GALAXY NGC-3079; VIRGO CLUSTER; RADIO; EMISSION; NUCLEI; GAS; SPECTROSCOPY; STARBURST; HYDROGEN; NGC-6240 AB We present multiwavelength observations of the interstellar medium in the disturbed galaxy NGC 4438. We find extended emission-line filaments, which are kinematically unrelated to the galaxy disk. For one of these features, an extended loop, we propose a scheme in which the ''bubble'' seen at radio wavelengths has swept a clear path for outflowing material from the nucleus to ionize more distant material. Another radial emission-line feature might represent shocks in the disk along a gravitationally-defined caustic produced during a tidal encounter, or a ''searchlight beam'' escaping the inner dusty regions of the galaxy. Energy-balance arguments favor the shock picture, but further study will be important in understanding this feature. Emission-line ratios indicate that shocks may be important in the energetics of the interstellar medium (ISM) through much of the disk of NGC 4438; the alternative is star formation in a uniformly very dense ISM. We use K-band data to locate the stellar peak of the galaxy, which is just outside the prominent radio-continuum loop or shell feature. The nucleus itself is at most a very weak radio source. However, the more extended radio structure shows that energetic events have taken place in the innermost few hundred parsecs of NGC 4438. The interstellar medium of NGC 4438 may show at once the impact of nuclear energy input (from an AGN or cocooned starburst), perturbation by the companion NGC 4435, and interaction with the dense intergalactic medium in the Virgo core. C1 CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. RP KEEL, WC (reprint author), UNIV ALABAMA,DEPT PHYS & ASTRON,BOX 870324,TUSCALOOSA,AL 35487, USA. OI Keel, William/0000-0002-6131-9539 NR 46 TC 11 Z9 11 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1993 VL 106 IS 1 BP 236 EP & DI 10.1086/116631 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ882 UT WOS:A1993LJ88200018 ER PT J AU LATTER, WB HORA, JL KELLY, DM DEUTSCH, LK MALONEY, PR AF LATTER, WB HORA, JL KELLY, DM DEUTSCH, LK MALONEY, PR TI A NEW NEAR-INFRARED IMAGING STUDY OF AFGL-2688 SO ASTRONOMICAL JOURNAL LA English DT Article ID BIPOLAR REFLECTION NEBULAE; PROTO-PLANETARY NEBULAE; MOLECULAR OUTFLOW; MASS-LOSS; CRL-2688; STARS; EVOLUTION; CRL-618; SPECTROSCOPY; ORIGIN AB The object AFGL 2688 is a bipolar nebula surrounding a post-asymptotic giant branch star and is in transition toward becoming a planetary nebula. We present new near-infrared images in the I, J, H, and K bandpasses. These images reveal a wealth of structure in the nebula not previously seen. We find that the northern lobe is not smooth, but clumpy. There is evidence in the I-band image for periodic variations in mass-loss rate. In addition, we present narrowband images centered on the v = 1 --> 0 S ( 1 ) line of molecular hydrogen (lambda = 2.121 mum) and nearby continuum, obtained with a new variable-wavelength narrowband-filter mechanism. The narrowband images reveal that broadband flux found in the equatorial region is dominated by line emission from vibrationally excited molecular hydrogen. H-2 emission is also present in the lobes. Our K-band images show the equatorial emission to be in the form of a ring or torus extending around the object at a distance R approximately 7 X 10(16) (D/1 kpc) cm. Mechanisms for exciting the equatorial H-2 emission are discussed; we conclude that shocks are the only plausible source. We have analyzed the broadband images using models which assume single scattering of photons from the central star. We find that the bipolar axis is inclined to the plane of the sky by i approximately 5-degrees. The images are best reproduced by models in which the density of scattering dust decreases fairly rapidly with increasing stellar latitude, with little or no dust near the poles. Furthermore, the optical depth is found to have very little wavelength dependence, which implies that the dust in AFGL 2688 is different from that in the interstellar medium. This result is consistent with polarimetric studies, which find that the scattering grains are likely to be large graphite particles. C1 INST ASTRON,HONOLULU,HI 96822. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. UNIV CALIF BERKELEY,BERKELEY,CA 94720. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. RP LATTER, WB (reprint author), ASSOC UNIV INC,NATL RADIO ASTRON OBSERV,949 N CHERRY AVE,CAMPUS BLDG 65,TUCSON,AZ 85721, USA. OI Hora, Joseph/0000-0002-5599-4650 NR 61 TC 48 Z9 48 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1993 VL 106 IS 1 BP 260 EP & DI 10.1086/116634 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ882 UT WOS:A1993LJ88200021 ER PT J AU SEKANINA, Z AF SEKANINA, Z TI EFFECTS OF DISCRETE-SOURCE OUTGASSING ON MOTIONS OF PERIODIC COMETS AND DISCONTINUOUS ORBITAL ANOMALIES (VOL 105, PG 702, 1993) SO ASTRONOMICAL JOURNAL LA English DT Correction, Addition RP SEKANINA, Z (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1993 VL 106 IS 1 BP 401 EP 401 DI 10.1086/116650 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ882 UT WOS:A1993LJ88200037 ER PT J AU PEREZ, MR GRADY, CA THE, PS AF PEREZ, MR GRADY, CA THE, PS TI UV SPECTRAL VARIABILITY IN THE HERBIG AE STAR HR-5999 .11. THE ACCRETION INTERPRETATION SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, PRE-MAIN-SEQUENCE; STARS, VARIABLE; ACCRETION, ACCRETION DISKS; STARS, INDIVIDUAL, HR-5999; ACCRETION; HR-5999 ID PICTORIS CIRCUMSTELLAR DISK; Z-CANIS MAJORIS; T-TAURI STARS; BETA-PICTORIS; FU ORIONIS; LINES AB We report recent IUE high- and low-dispersion observations with the IUE long wavelength camera (LWP) and short wavelength camera (SWP) of the Herbig Ae star HR 5999. We have found a dramatic change in the structure of the Mg II h and k lines (2795.5, 2802.7 angstrom) along with some continuum flux excesses especially at the short end of the SWP camera. LWP high-dispersion observations of HR 5999 obtained between 1979 and 1990, at times of comparatively low UV continuum fluxes, exhibit P Cygni type III profiles in the Mg II resonance doublet. In contrast, observations made from September 1990 through March 16-18, 1992, with high UV continuum fluxes, present Mg II lines with reverse P Cygni profiles indicative of some active episodic accretion. Accreting gas can also be detected in the additional red wings of the various Fe II and Mn II absorption lines, with velocities up to +300-350 km s-1 (September 1990). By September 10, 1992 the Mg II profile had returned to the type III P Cygni profile similar to those from earlier spectra. The correlation between the presence of large column densities of accreting gas and the continuum light variations supports suggestions by several authors that HR 5999 is surrounded by an optically thick, viscously heated accretion disk. Detection of accreting gas in the line of sight to HR 5999 permits us to place constraints on our viewing geometry for this system. A discussion is included comparing the spectral and physical similarities between HR 5999 and the more evolved proto-planetary candidate systems beta Pictoris. C1 APPL RES CORP, LANDOVER, MD 20785 USA. UNIV AMSTERDAM, ASTRON INST ANTON PANNEKOEK, 1098 SJ AMSTERDAM, NETHERLANDS. RP PEREZ, MR (reprint author), NASA, GODDARD SPACE FLIGHT CTR,ASTRON PROGRAM,CSC, INT ULTRAVIOLET EXPLORER OBSERV, CODE 6849, GREENBELT, MD 20771 USA. NR 51 TC 36 Z9 36 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 JUL PY 1993 VL 274 IS 2 BP 381 EP 390 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN548 UT WOS:A1993LN54800006 ER PT J AU GRADY, CA PEREZ, MR THE, PS AF GRADY, CA PEREZ, MR THE, PS TI THE ACCRETING CIRCUMSTELLAR GAS ENVELOPE OF HD-176386 A YOUNG STAR IN THE R-CORONAE AUSTRINAE STAR-FORMATION REGION SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, PRE-MAIN-SEQUENCE; ACCRETION; STARS, INDIVIDUAL; HD-176386; ULTRAVIOLET, STARS ID HERBIG AE/BE STARS; ORIONIS AB We report recent and archival IUE observations of the Herbig Be star HD 176386. We find accreting gas toward the star with velocities up to +300 km s-1 in C IV and Si IV. Detection of these species in a B9.5 star is consistent with collisional ionization of the accreting gas to temperatures in excess of the stellar T(eff). The IUE data also provide evidence for the presence of discrete absorption features similar to those observed in optical and UV spectra of beta Pic. The accreting gas column densities, and maximum accretion velocity are intermediate between those seen in younger Herbig Ae/Be stars such as HR 5999 and HD 45677 and field systems such as beta Pic and 51 Oph. These data suggest a gradual transition from the optically thick (continuum), high mass accretion rates seen in the younger Herbig Ae/Be stars to optically thin accretion typical of systems such as beta Pic, and that the time scale for such a transition for a B9.5 star appears to be 1.5 less-than-or-equal-to t less-than-or-equal-to 2.8 Myr. C1 NASA, GODDARD SPACE FLIGHT CTR,GSFC,IUE OBSERV,CSC, ASTRON PROGRAMS, GREENBELT, MD 20771 USA. UNIV AMSTERDAM, ASTRON INST ANTON PANNEKOEK, 1098 SJ AMSTERDAM, NETHERLANDS. RP GRADY, CA (reprint author), APPL RES CORP, SUITE 120, 8201 CORP DR, LANDOVER, MD 20785 USA. NR 16 TC 21 Z9 21 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 JUL PY 1993 VL 274 IS 3 BP 847 EP 850 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LP334 UT WOS:A1993LP33400022 ER PT J AU HARRISON, RA CARTER, MK CLARK, TA LINDSEY, C JEFFERIES, JT SIME, DG WATT, G ROELLIG, TL BECKLIN, EE NAYLOR, DA TOMPKINS, GJ BRAUN, D AF HARRISON, RA CARTER, MK CLARK, TA LINDSEY, C JEFFERIES, JT SIME, DG WATT, G ROELLIG, TL BECKLIN, EE NAYLOR, DA TOMPKINS, GJ BRAUN, D TI AN ACTIVE SOLAR PROMINENCE IN 1.3 MM RADIATION SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE SUN; PROMINENCE; RADIO ID CHROMOSPHERE AB We present new millimetre-wavelength observations of an active solar prominence. Observations made over a two-day period with the James Clerk Maxwell Telescope on Mauna Kea, Hawaii, give a unique view in 1.3 mm radiation of the spectacular prominence that appeared on the west solar limb in the total solar eclipse of 11 July 1991. C1 UNIV CALGARY, DEPT PHYS & ASTRON, CALGARY T2N 1N4, ALBERTA, CANADA. UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. NATL OPT ASTRON OBSERV, TUCSON, AZ 85726 USA. JOINT ASTRON CTR, HILO, HI 96720 USA. NATL CTR ATMOSPHER RES, HIGH ALTITUDE OBSERV, BOULDER, CO 80307 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV CALIF LOS ANGELES, DEPT ASTRON, LOS ANGELES, CA 90024 USA. UNIV LETHBRIDGE, DEPT PHYS, LETHBRIDGE T1K 3M4, ALBERTA, CANADA. RP HARRISON, RA (reprint author), RUTHERFORD APPLETON LAB, DIDCOT OX11 0QX, OXON, ENGLAND. NR 9 TC 6 Z9 6 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 JUL PY 1993 VL 274 IS 1 BP L9 EP L12 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN547 UT WOS:A1993LN54700003 ER PT J AU PAGANI, L LANGER, WD CASTETS, A AF PAGANI, L LANGER, WD CASTETS, A TI 1ST TENTATIVE DETECTION OF THE MOLECULAR-OXYGEN ISOTOPOMER (OO)-O-16-O-18 IN INTERSTELLAR CLOUDS SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE LINE, IDENTIFICATION; ISM, ABUNDANCES; ISM, INDIVIDUAL OBJECTS, L134N, NGC-7538; ISM, MOLECULES; RADIO LINES, INTERSTELLAR ID SEARCH; CHEMISTRY AB We report the first tentative detection of molecular oxygen in interstellar clouds by observation of the 234 GHz (N,J) = (2,1) - (0,1) line of the isotopomer O-16O-18 towards L134N. The line has a peak intensity of 18 +/- 6 mK and an integrated intensity of 5.3 +/- 1.8 mK km s-1. Two other lines are present within the (CO)-C-12 linewidth which are probably unidentified lines, but could arise from other weaker clumps. We also detected a feature in NGC 7538 in our first observing run with a peak intensity of 10.0 +/- 2.2 mK and an integrated intensity of 13 +/- 2 mK km s-1. However, we could not confirm this detection during our last observing session and, although we checked that this is not a telluric line, we believe that this line is suspicious. The ratio of O-16O-18/(CO)-O-18 in L134N is 0.8 if we restrict the (CO)-O-18 column density to the O-16O-18 linewidth and 0.4 using the entire (CO)-O-18 line. The corresponding O2/CO ratio (0.2 to 0.4) implies that the fractional abundance of gaseous oxygen is about (4-8) x 10(-5), in agreement with gas phase chemical models. We also observed two other cold dark clouds (B5 and TMC 2) but without success; our upper limits for these sources are significantly below those reported previously but above our tentative detection in L134N. C1 JET PROP LAB, MS 169-506, PASADENA, CA 91109 USA. OBSERV GRENOBLE, F-38041 GRENOBLE, FRANCE. RP PAGANI, L (reprint author), OBSERV MEUDON, DEMIRM, CNRS, URA 336, F-92195 MEUDON, FRANCE. NR 14 TC 20 Z9 20 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 JUL PY 1993 VL 274 IS 1 BP L13 EP L16 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LN547 UT WOS:A1993LN54700004 ER PT J AU SEMBACH, KR DANKS, AC SAVAGE, BD AF SEMBACH, KR DANKS, AC SAVAGE, BD TI OPTICAL STUDIES OF INTERSTELLAR MATERIAL IN LOW-DENSITY REGIONS OF THE GALAXY .1. A SURVEY OF INTERSTELLAR NA-I AND CA-II ABSORPTION TOWARD 57 DISTANT STARS SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE INTERSTELLAR MEDIUM, ABUNDANCES; CLOUDS; STRUCTURE; GALAXY, GENERAL ID INTER-STELLAR LINES; GLOBULAR-CLUSTER M22; SOUTHERN OB STARS; GALACTIC PLANE; MILKY-WAY; H-I; SPECTRAL CLASSIFICATIONS; SPACE DISTRIBUTION; HALO STAR; B-STARS AB We present high-resolution spectra of the Na I D and Ca II K lines toward 57 late-O and early-B stars along extended (d > 1 kpc) low density paths through the Milky Way disk and halo. The sight lines preferentially sample diffuse gas in the interstellar medium (ISM) along interarm, Galactic center, and high latitude directions. We measure equivalent widths, apparent column densities, and absorption component structure. The Ca II to Na I ratios presented as a function of velocity for each sight line exhibit variations due to elemental depletion, ionization, and density enhancements. Absorption along high latitude sight lines is kinematically simpler than it is along interarm and Galactic center sight lines. Galactic rotation noticeably broadens the absorption profiles of distant stars located in these latter directions. Along several sight lines, we see Ca II absorption at velocities corresponding to large distances (Absolute value of z is similar to 1 kpc) from the Galactic plane. The effects of differences in the Ca II and Na I scale heights and non-zero velocity dispersions are readily apparent in the data. Brief notes are given for several sight lines with interesting absorption properties. In future articles we will address the scientific results pertinent to the data and measurements contained in this paper. C1 UNIV WISCONSIN,WASHBURN OBSERV,MADISON,WI 53706. HUGHES STX,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 89 TC 94 Z9 94 U1 0 U2 0 PU EDITIONS PHYSIQUE PI LES ULIS CEDEX PA Z I DE COURTABOEUF AVE 7 AV DU HOGGAR, BP 112, 91944 LES ULIS CEDEX, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD JUL PY 1993 VL 100 IS 1 BP 107 EP 171 PG 65 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LK379 UT WOS:A1993LK37900007 ER PT J AU STRASSMEIER, KG HALL, DS FEKEL, FC SCHECK, M AF STRASSMEIER, KG HALL, DS FEKEL, FC SCHECK, M TI A CATALOG OF CHROMOSPHERICALLY ACTIVE BINARY STARS (2ND EDITION) SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE STARS, CHROMOSPHERES OF; STARS, BINARIES, SPECTROSCOPIC; STARS, RS-CVN, BY-DRA BINARIES; STARS, LATE TYPE; CATALOGS AB The catalog contains 206 spectroscopic binary systems with at least one late-type component that shows Ca II H and K emission in its spectrum. These systems include the classical RS CVn binaries and BY Dra binaries. The catalog summarizes information on the photometric, spectroscopic, orbital, and physical properties of the systems as well as space motions and positions. Up to 42 ''parameters'' for each stellar system are listed followed by the appropriate reference to direct interested colleagues to the original papers. A comprehensive selection of further information for each star is given in the individual notes. In addition, the catalog contains a candidate list of 138 stars that have similar characteristics but are not definitely known binaries or have not had Ca II H and K emission observed. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB ES52,HUNTSVILLE,AL 35812. VANDERBILT UNIV,DYER OBSERV,NASHVILLE,TN 37235. RP STRASSMEIER, KG (reprint author), UNIV WIEN,INST ASTRON,TURKENSCHANZSTR 17,A-1180 VIENNA,AUSTRIA. NR 3 TC 352 Z9 353 U1 0 U2 1 PU EDITIONS PHYSIQUE PI LES ULIS CEDEX PA Z I DE COURTABOEUF AVE 7 AV DU HOGGAR, BP 112, 91944 LES ULIS CEDEX, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD JUL PY 1993 VL 100 IS 1 BP 173 EP 225 PG 53 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LK379 UT WOS:A1993LK37900008 ER PT J AU CONWAY, JE MURPHY, DW AF CONWAY, JE MURPHY, DW TI HELICAL JETS AND THE MISALIGNMENT DISTRIBUTION FOR CORE-DOMINATED RADIO-SOURCES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES; JETS ID ACTIVE GALACTIC NUCLEI; RELATIVISTIC JETS; COMPLETE SAMPLE; QUASARS; MODELS; POLARIZATION; STATISTICS; MOTION AB The distribution of apparent misalignment between the position angle of VLBI and VLA scale jets in core-dominated radio sources shows an unexpected bimodal form with one peak close to 0-degrees and the other near 90-degrees. We find that this misalignment distribution implies that there are two populations of core-dominated radio sources. The aligned population can be explained by sources with straight VLBI jets and small, randomly oriented, intrinsic bends between parsec and kiloparsec scales. In contrast the misaligned sources must have parsec-scale jets which are curved into low-pitch (i.e., gently curving) helices. Such a geometry when combined with the selection effects due to relativistic beaming can, under certain conditions, naturally explain these orthogonal sources. Such a helical distortion might be caused either by Kelvin-Helmholtz instabilities or precession of the jet ejection axis. In order to fit the presently observed misalignment distribution the simplest such helical model requires that misaligned sources must have core bulk Lorentz factors gamma > 20 (15-degrees/zeta), where zeta is the half-cone opening angle of the helix. Observations of lobe-dominated sources suggest that zeta < 15-degrees; implying gamma > 20. Once the effects of jet curvature are taken into account, such large Lorentz factors can be made consistent with the observed proper motions provided the Hubble constant is toward the lower end of its plausible range (i.e., H-0 almost-equal-to 40 km s-1 Mpc-1). If the Hubble constant is larger, then either the jet decelerates between core and VLBI scales or the bulk flow and pattern gamma are decoupled. C1 CALTECH,OWENS VALLEY RADIO OBSERV,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. NR 43 TC 81 Z9 81 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1993 VL 411 IS 1 BP 89 EP 102 DI 10.1086/172809 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LH604 UT WOS:A1993LH60400008 ER PT J AU KNIFFEN, DA BERTSCH, DL FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KWOK, PW LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL PINKAU, K SCHNEID, E SREEKUMAR, P THOMPSON, DJ AF KNIFFEN, DA BERTSCH, DL FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KWOK, PW LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL PINKAU, K SCHNEID, E SREEKUMAR, P THOMPSON, DJ TI TIME VARIABILITY IN THE GAMMA-RAY EMISSION OF 3C-279 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, OBSERVATIONS; QUASARS, INDIVIDUAL (3C-279) ID COS-B; ENERGY; TELESCOPE; RADIATION; 3C273 AB Following the initial detection of 3C 279 as an intense high-energy gamma-ray emitter during a 1991 June 16-28 observation, the EGRET instrument on the Compton Gamma Ray Observatory made a second observation during 1991 October 3-17. Low-sensitivity observations were also made during 1991 October 12-31 and 1992 April. The relatively intense June fluxes allowed the time structure to be determined down to the level of half-days. During this period a flux enhancement of about a factor of 4 is seen, lasting several days. The October exposures show fluxes somewhat below the minimum June flux, with no significant evidence of time variability. The 1992 April fluxes are well off the main instrument axis, and so the statistics are less compelling, but the evidence appears to show additional time variability. The observations are consistent with a model in which the gamma rays result from Compton scattering of low-energy photons by relativistic electrons in a jet. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MAX PLANCK INST PHYS & ASTROPHYS,W-8046 GARCHING,GERMANY. STANFORD UNIV,HANSEN EXPTL PHYS LAB,STANFORD,CA 93405. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP KNIFFEN, DA (reprint author), HAMPDEN SYDNEY COLL,DEPT PHYS & ASTRON,HAMPDEN SYDNEY,VA 23943, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 32 TC 139 Z9 141 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1993 VL 411 IS 1 BP 133 EP 136 DI 10.1086/172813 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LH604 UT WOS:A1993LH60400012 ER PT J AU HOLLIS, JM MICHALITSIANOS, AG AF HOLLIS, JM MICHALITSIANOS, AG TI EVIDENCE FOR PRECESSION OF THE R-AQUARII JET SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (R-AQUARII); ISM, JETS AND OUTFLOWS ID SYSTEM; NEBULA AB Comparison of Hubble Space Telescope [O III] 5007 angstrom images obtained with the Faint Object Camera (FOC), and 6 cm radio continuum images acquired with the Very Large Array (VLA) of the jet in the R Aqr binary system indicates that the regions of peak optical and peak radio emission are not cospatial. Previous observations have shown that the radio and optical regions are in general coincident but have had insufficient resolution to discern spatial differences in the peak emitting regions at these disparate wavelengths. In this work, the [O III] jet structure is derived from restored FOC imagery, which has been convolved with an elliptical Gaussian of the same size (0''.6 x 0''.5) as the restoring beam of the 6 cm VLA maps, affording image comparison at the same spatial resolution. At increasing distances from the central star, [O III] emission knots that comprise the optical jet are found at systematically larger position angles when compared with corresponding features in the radio-amounting to as much as a approximately 2''-3'' spatial difference at a distance of approximately 10'' from the central star. This morphology suggests a ''garden-hose'' model in which [O III] emission defines the leading edge of a rotating collimated stream as it encounters ambient circumstellar material. The angular separation of [O III] and radio continuum emission can be understood in terms of a shock formed when ejecta in the stream interacts with previously existing circumstellar material and subsequently cools by nebular line emission. The shock front is followed by a cooler compressed region dominated by radio continuum free-free emission. Additionally, from an analysis of proper motions of the discrete radio jet components, we confirm an ''event'' separation which suggests a binary period of approximately 44 yr for the case of a jet undergoing constant acceleration. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HOLLIS, JM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,CODE 930,GREENBELT,MD 20771, USA. NR 22 TC 11 Z9 11 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1993 VL 411 IS 1 BP 235 EP 238 DI 10.1086/172822 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LH604 UT WOS:A1993LH60400021 ER PT J AU TEGLER, SC WEINTRAUB, DA ALLAMANDOLA, LJ SANDFORD, SA RETTIG, TW CAMPINS, H AF TEGLER, SC WEINTRAUB, DA ALLAMANDOLA, LJ SANDFORD, SA RETTIG, TW CAMPINS, H TI DETECTION OF THE 2165 INVERSE CENTIMETER (4.619 MICRON) XCN BAND IN THE SPECTRUM OF L1551 IRS-5 SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, INTERSTELLAR, LINES; ISM, INDIVIDUAL (L1551 IRS-5); ISM, MOLECULES; LINE, IDENTIFICATION ID INTERSTELLAR GRAINS; MOLECULAR CLOUDS; COMET P/HALLEY; ICE ANALOGS; CO; ABSORPTION; STARS; SPECTROSCOPY; PROTOSTARS; OBJECTS AB We report the detection of a broad absorption band at 2165 cm-1 (4.619 mum) in the spectrum of L1551 IRS 5. New laboratory results over the 2200-2100 cm-1 wavenumber interval (4.55-4.76 mum), performed with realistic interstellar ice analogs, suggest that this feature is due to a CN-containing compound. We will refer to this compound as XCN. We also confirm the presence of frozen CO (both in nonpolar and polar matrices) through absorption bands at 2140 cm-1 (4.67 mum) and 2135 cm-1 (4.68 mum). The relative abundance of solid-state CO to frozen H2O is approximately 0.13 while the abundance of XCN seems comparable to that of frozen CO. C1 VANDERBILT UNIV,DEPT PHYS & ASTRON,NASHVILLE,TN 37235. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV FLORIDA,DEPT ASTRON,GAINESVILLE,FL 32611. RP TEGLER, SC (reprint author), UNIV NOTRE DAME,DEPT PHYS & ASTRON,NOTRE DAME,IN 46556, USA. NR 38 TC 49 Z9 49 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1993 VL 411 IS 1 BP 260 EP 265 DI 10.1086/172825 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LH604 UT WOS:A1993LH60400024 PM 11539184 ER PT J AU JONES, TJ HUMPHREYS, RM GEHRZ, RD LAWRENCE, GF ZICKGRAF, FJ MOSELEY, H CASEY, S GLACCUM, WJ KOCH, CJ PINA, R JONES, B VENN, K STAHL, O STARRFIELD, SG AF JONES, TJ HUMPHREYS, RM GEHRZ, RD LAWRENCE, GF ZICKGRAF, FJ MOSELEY, H CASEY, S GLACCUM, WJ KOCH, CJ PINA, R JONES, B VENN, K STAHL, O STARRFIELD, SG TI IRC +10420 - A COOL HYPERGIANT NEAR THE TOP OF THE H-R DIAGRAM SO ASTROPHYSICAL JOURNAL LA English DT Article DE POLARIZATION; STARS, EVOLUTION; STARS, INDIVIDUAL (IRC + 10420); STARS, SUPERGIANTS ID INFRARED SPECKLE INTERFEROMETRY; MASS-LOSS RATES; WAVELENGTH DEPENDENCE; EVOLVED STARS; OH/IR STARS; DUST SHELLS; OH MASERS; M-GIANTS; POLARIMETRY; MICRONS AB New data are reported for the OH/IR star IRC + 10420, including optical/infrared imaging, spectroscopy, polarimetry, and photometry. We conclude the following: 1. The optical spectrum is that of a very luminous F supergiant (F Ia+) with a very strong O I blend at 7774 angstrom. Halpha is strongly in emission and shows a double-peaked profile similar to the emission seen in stars with rotating equatorial disks. 2. The optical image taken through polarizing filters is elongated, and shows that the star must be intrinsically polarized at a position angle near 90-degrees. The 8.7 mum image is also elongated, but at a position angle near 150-degrees. 3. The optical/infrared polarization is composed of a strong interstellar component and a complex intrinsic component. The intrinsic position angle in the optical is about 100-degrees, but rotates to about 140-degrees in the infrared. 4. Analysis of the infrared polarization, the reddening of the optical energy distribution, and the stellar radial velocity determined from the optical spectrum indicates that IRC +10420 is at a distance of 4-6 kpc. The resulting luminosity of the star is M(bol) = -9.6 +/- 0.5 mag (5 kpc), near the top of the H-R diagram at or just below the Humphreys-Davidson limit. 5. There has been a decline in the flux from the 1-7 mum continuum from the mid-1970s to the mid-1980s, whereas the optical energy distribution and the 10 mum silicate feature have remained largely unchanged over the same time period. We propose a model for IRC +10420 in which a true core-burning supergiant is surrounded by a rotating equatorial disk of gas and dust that is viewed from about midway above the plane. Dissipation of dust near the star is responsible for the drop in the infrared continuum. The polarization and OH emission are caused by a complex distribution of gas and dust that surrounds the star and its disk from an earlier phase of evolution. IRC +10420 may be evolving from a red supergiant to the blue side of the H-R diagram, perhaps to become a Wolf-Rayet star. We argue that it is now in a phase of evolution that is analogous to that of degenerate core giants evolving through the proto-planetary nebula phase, but at a much higher luminosity. C1 LANDESSTERNWARTE KONIGSTUHL,W-6900 HEIDELBERG 1,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & ASTROPHYS LAB,GREENBELT,MD 20771. USN,RES LAB,DIV SPACE SCI,WASHINGTON,DC 20375. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. RP JONES, TJ (reprint author), UNIV MINNESOTA,DEPT ASTRON,116 CHURCH ST,MINNEAPOLIS,MN 55455, USA. NR 73 TC 95 Z9 97 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1993 VL 411 IS 1 BP 323 EP 335 DI 10.1086/172832 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LH604 UT WOS:A1993LH60400031 ER PT J AU MISHCHENKO, MI AF MISHCHENKO, MI TI ON THE NATURE OF THE POLARIZATION OPPOSITION EFFECT EXHIBITED BY SATURNS RINGS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MINOR PLANETS; PLANETS AND SATELLITES, INDIVIDUAL (SATURN); POLARIZATION; RADIATIVE TRANSFER ID WEAK LOCALIZATION; BACKSCATTERING ENHANCEMENT; COHERENT BACKSCATTERING; MULTIPLE-SCATTERING; RADIATIVE-TRANSFER; LIGHT-SCATTERING; NONSPHERICAL PARTICLES; PLANETARY ATMOSPHERES; OPTICAL POLARIMETRY; B-RING AB Saturn's A and B rings exhibit two intriguing opposition phenomena, namely, the unusually narrow photometric and polarization opposition effects. Specifically, the intensity of the reflected light measured in the visible has a strong and very narrow peak centered at zero phase angle and superposed on a smooth photometric phase curve, while the reflected polarization, being zero at zero phase angle, becomes negative and almost reaches its maximum negative value at a small phase angle of several tenths of degree. The small angular width of both phenomena makes it difficult to explain them on the basis of the commonly used shadowing models. On the other hand, it is known from controlled laboratory experiments and theoretical studies that a strong and very narrow opposition peak in the reflected intensity can be produced by coherent back-scattering of light from powder-like layers composed of small regolithic grains. Recently, Mishchenko and Dlugach assumed that macroscopic particles of Saturn's rings are covered with a layer of submicrometer-sized regolithic ice grains and demonstrated that coherent backscattering of sunlight from this layer can explain the unusually narrow photometric opposition effect observed for Saturn's A and B rings in the visible. In this paper, we use a rigorous vector theory of coherent backscattering, developed recently for very small (pointlike) scattering grains by Ozrin, to show that for subwavelength-sized regolithic particles, the photometric opposition effect is accompanied by a polarization opposition effect of the same angular width. The common origin of the two coherent opposition phenomena was also demonstrated in recent controlled laboratory experiments by van Albada, van der Mark, and Lagendijk, although different terminology was exploited. These results may be considered an evidence that the polarization opposition effect observed for Saturn's rings in the visible has the same origin as the photometric opposition effect and is due to coherent backscattering of light from the regolithic layer composed of the submicrometer-sized ice grains. A remarkable opposition brightening similar to that for Saturn's rings has also been observed for some icy satellites and E-type asteroids. It is suggested that if the regolithic grains responsible for the observed opposition spikes are smaller that the wavelength, then the polarization opposition effect should also be observed for these objects at phase angles less than 1 degree. RP MISHCHENKO, MI (reprint author), NASA,GODDARD INST SPACE STUDIES,HUGHES STX CORP,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Mishchenko, Michael/D-4426-2012 NR 76 TC 103 Z9 105 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1993 VL 411 IS 1 BP 351 EP 361 DI 10.1086/172835 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LH604 UT WOS:A1993LH60400034 ER PT J AU DOWDY, JF AF DOWDY, JF TI OBSERVATIONAL EVIDENCE FOR HOTTER TRANSITION REGION LOOPS WITHIN THE SUPERGRANULAR NETWORK SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, MAGNETIC FIELDS; SUN, TRANSITION REGION; SUN, UV RADIATION ID CORONAL LOOPS; BRIGHT POINTS; QUIET-SUN; FLOWS AB We correlate EUV spectroheliograms of the quiet Sun taken by the Harvard EUV Spectroheliometer on Skylab with a magnetogram taken within 15-20 minutes by the 40 channel magnetograph at Kitt Peak. Although the EUV spectroheliograms sample the entire temperature range of the transition region (10(4)-10(6) K), our focus is on the O VI and Ne VII ions which are formed in the hotter transition region and the Mg x ion which is formed in the corona. Since no imaged observations in lines from 2 x 10(5) K < T < 10(6) K temperature region have been made since Skylab, these data are unique in providing opportunities to investigate the hotter transition region and its relationship to the corona. The signature of an EUV intranetwork loop is a small EUV brightening located on the neutral line of a small magnetic bipole within the supergranular network. The data clearly show such features. Some of these features are visible at coronal temperatures, indicating that network loops can reach 10(6) K. Others are bright in the lines formed below 10(6) K but occur in regions of depleted coronal emission, which cannot be explained by models based on back-heating from a large-scale corona. We conclude that some fraction of the quite solar EUV output is generated within network loops that are effectively insulated from the corona. Although that fraction cannot be determined from these data due to their limited resolution, it is possibly the predominant component. RP DOWDY, JF (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SOLAR SCI BRANCH E552,HUNTSVILLE,AL 35812, USA. NR 21 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1993 VL 411 IS 1 BP 406 EP 409 DI 10.1086/172842 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LH604 UT WOS:A1993LH60400041 ER PT J AU BROSIUS, JW DAVILA, JM THOMPSON, WT THOMAS, RJ HOLMAN, GD GOPALSWAMY, N WHITE, SM KUNDU, MR JONES, HP AF BROSIUS, JW DAVILA, JM THOMPSON, WT THOMAS, RJ HOLMAN, GD GOPALSWAMY, N WHITE, SM KUNDU, MR JONES, HP TI SIMULTANEOUS OBSERVATIONS OF SOLAR PLAGE WITH THE SOLAR EXTREME-ULTRAVIOLET ROCKET TELESCOPE AND SPECTROGRAPH (SERTS), THE VLA, AND THE KITT PEAK MAGNETOGRAPH SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, CORONA; SUN, FACULAE, PLAGES; SUN, MAGNETIC FIELDS; SUN, RADIO RADIATION; SUN, UV RADIATION ID X-RAY OBSERVATIONS; ACTIVE REGIONS; MICROWAVE EMISSION; MAGNETIC-FIELDS; CORONAL LOOPS AB We obtained simultaneous images of solar plage on 1991 May 7 with NASA/Goddard Space Flight Center's Solar Extreme Ultraviolet Rocket Telescope and Spectrograph (SERTS), the Very Large Array (VLA),4 and the NASA/National Solar Observatory5 spectromagnetograph at the NSO/Kitt Peak Vacuum Telescope. Using intensity ratios of Fe XVI to Fe XV emission lines, we find that the coronal plasma temperature is (2.3-2.9) x 10(6) K throughout the region. The column emission measure ranges from 2.5 x 10(27) to 1.3 x 10(28) cm-5. The calculated structure and intensity of the 20 cm wavelength thermal bremsstrahlung emission from the hot plasma observed by SERTS is quite similar to the observed structure and intensity of the 20 cm microwave emission observed by the VLA. Using the Meyer (1991, 1992) revised coronal iron abundance, we find no evidence either for cool absorbing plasma or for contributions from thermal gyroemission. Using the observed microwave polarization and the SERTS plasma parameters, we calculate a map of the coronal longitudinal magnetic field. The resulting values, approximately 30-60 G, are comparable to extrapolated values of the potential field at heights of 5000 and 10,000 km. C1 UNIV MARYLAND,ASTRON PROGRAM,COLL PK,MD 20742. HUGHES STX CORP,LANHAM,MD 20706. APPL RES CORP,LANDOVER,MD 20785. NASA,GODDARD SPACE FLIGHT CTR,NATL SOLAR OBSERV,SW SOLAR STN,GREENBELT,MD 20771. RP BROSIUS, JW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 682,GREENBELT,MD 20771, USA. RI Holman, Gordon/C-9548-2012; Gopalswamy, Nat/D-3659-2012; Thompson, William/D-7376-2012 NR 42 TC 26 Z9 26 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1993 VL 411 IS 1 BP 410 EP & DI 10.1086/172843 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LH604 UT WOS:A1993LH60400042 ER PT J AU OWEN, FN WHITE, RA GE, JP AF OWEN, FN WHITE, RA GE, JP TI A 20 CENTIMETER VLA SURVEY OF ABELL CLUSTERS OF GALAXIES .3. IMAGES AND OPTICAL IDENTIFICATIONS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE GALAXIES, ACTIVE; GALAXIES, CLUSTERING; GALAXIES, JETS; RADIO CONTINUUM, GALAXIES; SURVEYS; TECHNIQUES, INTERFEROMETRIC ID LUMINOSITY RADIO GALAXIES AB We present radio contour maps, models, and optical identifications for 250 radio galaxies in Abell clusters of galaxies. C1 NASA,GODDARD SPACE FLIGHT CTR,CTR COMP SCI,GREENBELT,MD 20771. RP OWEN, FN (reprint author), NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801, USA. NR 15 TC 39 Z9 39 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 1993 VL 87 IS 1 BP 135 EP 178 DI 10.1086/191800 PG 44 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ017 UT WOS:A1993LJ01700004 ER PT J AU DOSCHEK, GA FEIBELMAN, WA AF DOSCHEK, GA FEIBELMAN, WA TI AN IMPROVED ULTRAVIOLET SPECTRAL-LINE LIST FOR THE SYMBIOTIC STAR RR-TELESCOPII SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE BINARIES, SYMBIOTIC; LINE, IDENTIFICATIONS; STARS, INDIVIDUAL (RR-TEL); ULTRAVIOLET, STARS ID TEL AB We have remeasured wavelengths and intensities of International Ultraviolet Explorer (IUE) spectra of the symbiotic star, RR Tel. The main work is centered on the long 820 minute exposure high-resolution spectrum obtained on 1983 June 18. The list is intended to serve as a source of improved intensities and wavelengths for the ultraviolet spectrum of this star. A complete line list with intensities based on this exposure has not been published previously. The strongest spectral lines are saturated in the 820 minute exposure, and intensities for these lines are mostly obtained from a 20 minute exposure obtained on the same day. A few intensities are obtained from other exposures if neither the 820 nor the 20 minute exposure is satisfactory. There are 111 lines in our list between 1168 and 1980 angstrom. Some of the very weakest lines may not be real. These are indicated by question marks. We also discuss some of the plasma diagnostics available using spectral tines of O V and O IV. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP DOSCHEK, GA (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375, USA. NR 8 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 1993 VL 87 IS 1 BP 331 EP 336 DI 10.1086/191806 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ017 UT WOS:A1993LJ01700010 ER PT J AU AUFDENBERG, JP AF AUFDENBERG, JP TI IUE SHORT-WAVELENGTH HIGH-DISPERSION LINE LIST FOR THE SYMBIOTIC NOVA RR-TELESCOPII SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE BINARIES, GENERAL; INSTRUMENTATION, SPECTROGRAPHS; LINE, IDENTIFICATION; STARS, INDIVIDUAL (RR-TELESCOPII); ULTRAVIOLET, STARS ID TEL AB An 820 minute and other long-exposure archival SWP IUE high-dispersion spectra of symbiotic star RR Tel have been combined to form a composite spectrum. In most of these spectra many lines are saturated, but weaker features appear above the continuum. Their wavelengths were measured from the composite spectrum and compared with the line list from a thorough study of RR Tel by Penston et al. ( 1983). Among the revised line list are 22 new line identifications from ions C III, O I, N I, Mg VI, Si I, S I, S IV, Fe II, and Ni II. N I exists inside RR Tel's H II region and is pumped by the hot component's continuum. The fluxes for all the lines in each of the spectra are presented. All of the observed ions show a secular flux decrease between 1978 and 1988. A list of SWP high-dispersion camera artifacts is also presented. The list was generated by comparing RR Tel spectra to a long-exposure sky flat. C1 NASA,GODDARD SPACE FLIGHT CTR,IUE OBSERV,COMP SCI CORP,ASTRON PROGRAMS,GREENBELT,MD 20771. RP AUFDENBERG, JP (reprint author), NEW MEXICO INST MIN & TECHNOL,DEPT PHYS,ASTROPHYS RES CTR,SOCORRO,NM 87801, USA. NR 9 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 1993 VL 87 IS 1 BP 337 EP 343 DI 10.1086/191807 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LJ017 UT WOS:A1993LJ01700011 ER PT J AU SMITH, EP AF SMITH, EP TI UIT OBSERVATIONS OF NGC-1275 SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID CLUSTERS; GALAXIES AB We present the results from UV imagery of NGC 1275 obtained using the Goddard Ultraviolet Imaging Telescope (UIT). We are able to study the UV morphology down to mu249 approximately 25 mag arcsec-2. There are significant non-axisymmetric structures in the UV continuum associated with the low-velocity filament system. Continuum from the high-velocity system may also be present. The large aperture UV colors indicate that although the mass function extends to approximately 5M., more massive objects are not present. This implies either a cessation of star formation during the last 50-100 Myr or a truncated initial mass function. RP SMITH, EP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD JUL PY 1993 VL 205 IS 1 BP 65 EP 68 DI 10.1007/BF00657958 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LX038 UT WOS:A1993LX03800010 ER PT J AU FOWLKES, JE KENNEDY, RS HETTINGER, LJ HARM, DL AF FOWLKES, JE KENNEDY, RS HETTINGER, LJ HARM, DL TI CHANGES IN THE DARK FOCUS OF ACCOMMODATION ASSOCIATED WITH SIMULATOR SICKNESS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID MOTION SICKNESS; STIMULUS AB The relationship between the dark focus of accommodation and simulator sickness, a form of motion sickness, was examined in three experiments. In Experiment 1, dark focus was measured in 18 college students in a laboratory setting before and after they viewed a projected motion scene depicting low altitude helicopter flight. In Experiments 2 and 3, dark focus was measured in pilots (N = 16 and 23, respectively) before and after they ''flew'' in moving-base helicopter flight simulators with optical infinity CRT visual systems. The results showed that individuals who experienced simulator sickness had either an inward (myopic) change in dark focus (Experiments 1 and 3) or attenuated outward shifts in dark focus (Experiment 2) relative to participants who did not get sick. These results are consonant with the hypothesis that parasympathetic activity, which may be associated with simulator sickness, should result in changes in dark focus that are in a myopic direction. Night vision goggles, virtual environments, extended periods in microgravity, and heads-up displays all produce related visual symptomatology. Changes in dark focus may occur in these conditions, as well, and should be measured. C1 ESSEX CORP,1040 WOODCOCK RD,SUITE 227,ORLANDO,FL 32803. ENGN & ECON RES,ORLANDO,FL. LOGICON TECH SERV INC,DAYTON,OH. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 30 TC 5 Z9 5 U1 0 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD JUL PY 1993 VL 64 IS 7 BP 612 EP 618 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA LK879 UT WOS:A1993LK87900005 PM 8357314 ER PT J AU SASAKI, M KUROSAKI, YS SPINWEBER, CL GRAEBER, RC TAKAHASHI, T AF SASAKI, M KUROSAKI, YS SPINWEBER, CL GRAEBER, RC TAKAHASHI, T TI FLIGHT CREW SLEEP DURING MULTIPLE LAYOVER POLAR FLIGHTS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB This study investigated changes in sleep after multiple transmeridian flights. The subjects were 12 8747 airline pilots operating on the following polar flight: Tokyo (TYO)-Anchorage (ANC)-London (LON)-Anchorage-Tokyo. Sleep polysomnograms were recorded on two baseline nights (B1, B2), during layovers, and, after returning to Tokyo, two recovery nights were recorded (R1, R2). In ANC (outbound), total sleep time (TST) was reduced and, sleep efficiency was low (72.0%). In London, time in bed (TIB) increased slightly, but sleep efficiency was still reduced. On return to ANC (inbound), there was considerable slow wave sleep (SWS) rebound and multiple awakenings reduced sleep efficiency to 76.8%. Sleep efficiency on R2 was significantly lower than on B1 (t-test, p < 0.05) but not different from R1. To sum up, sleep of aircrews flying multiple transmeridian flights is disrupted during layovers and this effect persists during the two recovery nights. As a result, there is a marked cumulative sleep loss during multi-legs polar route trip in comparison to single leg flights. These findings suggest that following such extensive transmeridian trips, crews should have at least three nights of recovery sleep in their home time zone before returning to duty. C1 UNIV CALIF SAN DIEGO,LA JOLLA,CA 92093. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SASAKI, M (reprint author), JAPAN AIRLINES,CTR OPERAT,DEPT FLIGHT CREW MED SERV,1-1 HANEDAKUKO 2 CHOME,OHTA KU,TOKYO 144,JAPAN. NR 14 TC 16 Z9 16 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD JUL PY 1993 VL 64 IS 7 BP 641 EP 647 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA LK879 UT WOS:A1993LK87900010 PM 8357319 ER PT J AU VANDERMEULEN, MCH BEAUPRE, GS CARTER, DR AF VANDERMEULEN, MCH BEAUPRE, GS CARTER, DR TI MECHANOBIOLOGIC INFLUENCES IN LONG-BONE CROSS-SECTIONAL GROWTH SO BONE LA English DT Article DE BONE; MECHANICAL ADAPTATION; BONE DEVELOPMENT; MODELING ID MECHANICAL-PROPERTIES; RAT FEMUR; STRAIN; INVIVO; AGE; PREDICTIONS; STRESS; TISSUE; MODELS; CHICK AB We developed a computer model to simulate the interaction of biological and mechanobiological factors in the development of the cross-sectional morphology of long bones. The model incorporated a strong influence of biologically induced bone formation during early development. In addition, an assumed mechanical loading history during growth and development corresponding to age-related changes in body weight and muscle mass was applied. Based on the bone stress stimulus generated by the assumed loads, mechanically induced apposition and resorption rates were calculated at the periosteal and endosteal surfaces using a previously developed bone modeling theory. These methods successfully emulated the growth-related changes seen in long bone diaphyseal structure as well as changes observed in mature bones during aging. The simulations recreated the rapid increase in bone dimensions during development, stabilizing at maturity, and then the gradual, age-related subperiosteal expansion and cortical thinning. Throughout the growth, development, and aging simulations, the values of the bone radii, area, moments of inertia, and apposition rates corresponded well with measurements documented by other researchers. C1 VET AFFAIRS MED CTR,CTR REHABIL RES & DEV,PALO ALTO,CA 94304. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP VANDERMEULEN, MCH (reprint author), STANFORD UNIV,DEPT MECH ENGN,BIOMECH ENGN PROGRAM,DIV DESIGN,TERMAN 551,STANFORD,CA 94305, USA. RI van der Meulen, Marjolein/D-1549-2010; Beaupre, Gary/B-9880-2013 OI van der Meulen, Marjolein/0000-0001-6637-9808; Beaupre, Gary/0000-0002-6211-7621 NR 50 TC 118 Z9 118 U1 0 U2 9 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 8756-3282 J9 BONE JI Bone PD JUL-AUG PY 1993 VL 14 IS 4 BP 635 EP 642 DI 10.1016/8756-3282(93)90085-O PG 8 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA LK846 UT WOS:A1993LK84600005 PM 8274306 ER PT J AU LAU, KM SUI, CH TAO, WK AF LAU, KM SUI, CH TAO, WK TI A PRELIMINARY-STUDY OF THE TROPICAL WATER CYCLE AND ITS SENSITIVITY TO SURFACE WARMING SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID MESOSCALE PROCESSES; CLIMATE MODELS; CLOUDS; FEEDBACK AB This paper presents the preliminary findings of an investigation of the water budget of tropical cumulus convection using the Goddard Cumulus Ensemble Model (GCEM). Results of an experiment designed to obtain a ''fingerprint'' in the tropical hydrologic cycle in response to surface warming are also presented. The ensemble mean water budget shows that the distribution of water vapor and cloud water in the tropical atmosphere is maintained as a result of a balance between moisture convergence (including cloud scale and large scale) and condensation and reevaporation by various microphysical species within the cumulus clusters. Under radiative convective equilibrium conditions, 66% of the precipitation reaching the ground comes from the convective region and 34% from the stratiform region. In a climate with above-normal sea surface temperature but fixed large-scale vertical velocity, tropical convection is enhanced with more abundant moisture sources. Water vapor is increased throughout the troposphere with the surplus largest near the surface and decreases monotonically up to 10 km. However, the percentage increase in water vapor is largest near 8 to 16 km. As a result of the warming, the freezing level in clouds is elevated resulting in a large increase (decrease) in cloud water just above (below) 5 km. As with water vapor, the fractional increase in cloud water and cloudiness amount is largest at the upper troposphere. In spite of the detailed microphysics and cloud-scale dynamical processes included in the GCEM, the results on changes in temperature and water vapor induced by surface warming are in agreement with those from general circulation models that use crude cumulus parameterization. This is consistent with previous findings that equilibrium water vapor distribution is a strong function of temperature. In an open domain such as the tropical convective environment, with a specified climatological vertical velocity, the ratio of increased precipitation to increased surface evaporation due to a 2-degrees-C surface warming is approximately 5. The increase is mostly found for convective rain and is negligible for stratiform rain. The climate implication of these changes is also discussed. RP LAU, KM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Lau, William /E-1510-2012; OI Lau, William /0000-0002-3587-3691; SUI, CHUNG-HSIUNG/0000-0003-2842-5660 NR 24 TC 31 Z9 31 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD JUL PY 1993 VL 74 IS 7 BP 1313 EP 1321 DI 10.1175/1520-0477(1993)074<1313:APSOTT>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP292 UT WOS:A1993LP29200002 ER PT J AU DU, P SALAMA, F LOEW, GH AF DU, P SALAMA, F LOEW, GH TI THEORETICAL-STUDY OF THE ELECTRONIC-SPECTRA OF A POLYCYCLIC AROMATIC HYDROCARBON, NAPHTHALENE, AND ITS DERIVATIVES SO CHEMICAL PHYSICS LA English DT Article ID DIFFUSE INTERSTELLAR BANDS; SPECTROSCOPY; AZANAPHTHALENES; FEATURES AB In order to preselect possible candidates for the origin of diffuse interstellar bands observed, semiempirical quantum mechanical method INDO/S was applied to the optical spectra of neutral, cationic, and anionic states of naphthalene and its hydrogen abstraction and addition derivatives. Comparison with experiment shows that the spectra of naphthalene and its ions were reliably predicted. The configuration interaction calculations with single-electron excitations provided reasonable excited state wavefunctions compared to ab initio calculations that included higher excitations. The degree of similarity of the predicted spectra of the hydrogen abstraction and derivatives to those of naphthalene and ions depends largely on the similarity of the pi electron configurations. For the hydrogen addition derivatives, very little resemblance of the predicted spectra to naphthalene was found because of the disruption of the aromatic conjugation system. The relevance of these calculations to astrophysical issues is discussed within the context of these polycyclic aromatic hydrocarbon models. Comparing the calculated electronic energies to the diffuse interstellar bands (DIBs), a list of possible candidates of naphthalene derivatives is established which provides selected candidates for a definitive test through laboratory studies. C1 NASA,AMES RES CTR MS 2456,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP DU, P (reprint author), MOLEC RES INST,845 PAGE MILL RD,PALO ALTO,CA 94304, USA. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 37 TC 41 Z9 41 U1 2 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD JUL 1 PY 1993 VL 173 IS 3 BP 421 EP 437 DI 10.1016/0301-0104(93)80157-5 PG 17 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LK349 UT WOS:A1993LK34900009 ER PT J AU BLANKENHORN, DH SELZER, RH CRAWFORD, DW BARTH, JD LIU, CR LIU, CH MACK, WJ ALAUPOVIC, P AF BLANKENHORN, DH SELZER, RH CRAWFORD, DW BARTH, JD LIU, CR LIU, CH MACK, WJ ALAUPOVIC, P TI BENEFICIAL-EFFECTS OF COLESTIPOL-NIACIN THERAPY ON THE COMMON CAROTID-ARTERY - 2-YEAR AND 4-YEAR REDUCTION OF INTIMA-MEDIA THICKNESS MEASURED BY ULTRASOUND SO CIRCULATION LA English DT Article DE CAROTID ARTERIES; ULTRASOUND; ATHEROSCLEROSIS; ANGIOGRAPHY; APOLIPOPROTEINS; CORONARY ARTERY DISEASE; LIPOPROTEINS ID CORONARY HEART-DISEASE; FEMORAL ATHEROSCLEROSIS; DESIGN-FEATURES; WALL THICKNESS; BYPASS GRAFTS; RISK-FACTORS; PROGRESSION; REGRESSION; HYPERCHOLESTEROLEMIA; VELOCITY AB Background. Controlled clinical trials have reported treatment effects evaluated with serial imaging in coronary and femoral but not cervical arteries. The Cholesterol Lowering Atherosclerosis Study, a coronary, cervical, and femoral angiographic trial of colestipol plus niacin, included a pilot study of standardized carotid ultrasound imaging. Methods and Results. Seventy-eight subjects had ultrasound studies at baseline, 2, and 4 years. Twenty-four drug and 22 placebo subjects had carotid ultrasound images at baseline, 2, and 4 years with matching cervical angiograms. Computer image processing was applied to ultrasound images of common carotid (far wall) and cervical angiograms. Computer operators were blind to treatment group. Carotid ultrasound measurements were tested for treatment effects and compared with measurements of atherosclerosis in coronary and cervical angiograms. Drug subjects showed significant progressive reduction in carotid thickness at 2 (P=.0001) and 4 years (P=.0001); placebo subjects significantly increased wall thickness at 2 and 4 years. Reduced levels of apolipoprotein B and increased levels of high density lipoprotein cholesterol and apolipoprotein C-III were significant predictors of carotid wall thinning. Ultrasound-measured carotid intima-media thickness was correlated at baseline with visually read coronary angiographic stenosis and at 2 years with a robust computer measurement of mild carotid atherosclerosis. Conclusions. Common carotid intima-media thickening can be reduced by colestipol-niacin treatment. Two-year image-processed carotid ultrasound trials can provide adequate power with 50 subjects per group to test for this treatment effect. C1 UNIV SO CALIF,SCH MED,DEPT MED,ATHEROSCLEROSIS RES LAB,2250 ALCAZAR ST,LOS ANGELES,CA 90033. OKLAHOMA MED RES FDN,OKLAHOMA CITY,OK 73104. INTERUNIV CARDIOL INST NETHERLANDS,DELFT,NETHERLANDS. UNIV SO CALIF,SCH MED,DEPT PREVENT MED,LOS ANGELES,CA 90033. JET PROP LAB,PASADENA,CA 91109. FU NHLBI NIH HHS [HL-45005, HL-23619, HL-40098] NR 48 TC 298 Z9 310 U1 1 U2 2 PU AMER HEART ASSOC PI DALLAS PA 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596 SN 0009-7322 J9 CIRCULATION JI Circulation PD JUL PY 1993 VL 88 IS 1 BP 20 EP 28 PG 9 WC Cardiac & Cardiovascular Systems; Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA LM127 UT WOS:A1993LM12700005 PM 8319334 ER PT J AU BERG, HE DUDLEY, GA HATHER, B TESCH, PA AF BERG, HE DUDLEY, GA HATHER, B TESCH, PA TI WORK CAPACITY AND METABOLIC AND MORPHOLOGIC CHARACTERISTICS OF THE HUMAN QUADRICEPS MUSCLE IN RESPONSE TO UNLOADING SO CLINICAL PHYSIOLOGY LA English DT Article DE ATROPHY; CAPILLARY SUPPLY; CITRATE SYNTHASE; DISUSE; FATIGUE; FIBER TYPES AND SIZE; INACTIVITY; UNWEIGHTING ID SKELETAL-MUSCLE; MOTOR UNIT; HINDLIMB SUSPENSION; THIGH MUSCLE; BED REST; IMMOBILIZATION; FATIGUE; RAT; EXERCISE; DISUSE AB The response of skeletal muscle to unweighting was studied in six healthy males who were subjected to four weeks of lower limb suspension. They performed three bouts of 30 consecutive maximal concentric knee extensions, before unloading and the day after (POST 1), 4 days after (POST 2) and 7 weeks after (REC) resumed weight-bearing. Peak torque of each contraction was recorded and work was calculated as the mean of the average peak torque for the three bouts and fatigability was measured as the decline in average peak torque over bouts. Needle biopsies were obtained from m. vastus lateralis of each limb before and at POST 1. Muscle fibre type composition and area. capillarity and the enzyme activities of citrate synthase (CS) and phosphofructokinase (PFK) were subsequently analyses. Mean average peak torque for the three bouts at POST1, POST2 and REC was reduced (P<0.05) by 17,13 and 7%, respectively. Fatigability was greater (P<0.05) at POST2 than before unloading. Type I, IIA and IIB percentage, Type I and II area and capillaries per fibre of Type I and II did not change (P>0.05) in response to unloading. The activity of CS, but not PFK, decreased (P<0.05) after unloading. The weight-bearing limb showed no changes in the variables measured. The results of this study suggest that this human lower limb suspension model produces substantial impairments of work and oxidative capacity of skeletal muscle. The performance decrements are most likely induced by lack of weight-bearing. C1 NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL. BIONET CORP,BIOMED & ENVIRONM LABS,KENNEDY SPACE CTR,FL. RP BERG, HE (reprint author), KAROLINSKA INST,DEPT PHYSIOL,ENVIRONM PHYSIOL LAB,S-10401 STOCKHOLM 60,SWEDEN. NR 37 TC 80 Z9 80 U1 1 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0144-5979 J9 CLIN PHYSIOL JI Clin. Physiol. PD JUL PY 1993 VL 13 IS 4 BP 337 EP 347 DI 10.1111/j.1475-097X.1993.tb00334.x PG 11 WC Physiology SC Physiology GA LM639 UT WOS:A1993LM63900002 PM 8370234 ER PT J AU PLOUTZ, LL TATRO, DL DUDLEY, GA CONVERTINO, VA AF PLOUTZ, LL TATRO, DL DUDLEY, GA CONVERTINO, VA TI CHANGES IN PLASMA-VOLUME AND BAROREFLEX FUNCTION FOLLOWING RESISTANCE EXERCISE SO CLINICAL PHYSIOLOGY LA English DT Article DE CAROTID-CARDIAC BAROREFLEX; EVANS BLUE DYE; HEMATOCRIT; HEMOGLOBIN; HYPOVOLEMIA; HYPERVOLEMIA; BENCH PRESS; LEG PRESS ID BARORECEPTOR-CARDIAC REFLEX; BLOOD-VOLUME; PROLONGED EXERCISE; RESPONSES; OSMOLALITY; PRESSURE; STRESS; HUMANS; RENIN AB The dynamics of change in plasma volume (PV) and baroreflex responses have been reported over 24 h immediately following maximal cycle exercise. The purpose of this study was to determine if PV and baroreflex showed similar changes for 24 h after resistance exercise. Eight men were studied on 2 test days, 1 week apart. On 1 day, per cent change (%DELTA) in PV was estimated at 0, 3, and 6 h after resistance exercise using haematocrit and haemoglobin. Baseline PV was measured 24 h after exercise using Evans blue dye. The carotid baroreceptor-cardiac reflex response was measured before, and 3, 6, 9,12, and 24 h post-exercise. Each subject performed six sets of the bench press and leg press with 10 repetitions per set with a load that induced failure within each set. On a control day, the protocol was used without exercise. Plasma volume did not change during the control day. There was a 20% decrease in PV immediately post-exercise; the recovery of the PV was rapid and complete within 3 h. PV was 20% greater 24 h post-exercise than on the control day. There were no differences in any of the baroreflex measurements. Therefore, it is suggested that PV shifts may occur without altering baroreflex sensitivity. C1 BIONET CORP,KENNEDY SPACE CTR,FL. NASA,KENNEDY SPACE CTR,FL. NR 30 TC 13 Z9 13 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0144-5979 J9 CLIN PHYSIOL JI Clin. Physiol. PD JUL PY 1993 VL 13 IS 4 BP 429 EP 438 DI 10.1111/j.1475-097X.1993.tb00342.x PG 10 WC Physiology SC Physiology GA LM639 UT WOS:A1993LM63900010 PM 8370241 ER PT J AU HIEL, C DITTMAN, D ISHAI, O AF HIEL, C DITTMAN, D ISHAI, O TI COMPOSITE SANDWICH CONSTRUCTION WITH SYNTACTIC FOAM CORE - A PRACTICAL ASSESSMENT OF POSTIMPACT DAMAGE AND RESIDUAL STRENGTH SO COMPOSITES LA English DT Article ID STRESS C1 TECHNION ISRAEL INST TECHNOL,HAIFA,ISRAEL. RP HIEL, C (reprint author), NASA,AMES RES CTR,EEM BRANCH,COMPOSITE MAT R&D PROGRAM,MOFFETT FIELD,CA 94035, USA. NR 5 TC 41 Z9 41 U1 0 U2 1 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0010-4361 J9 COMPOSITES JI Composites PD JUL PY 1993 VL 24 IS 5 BP 447 EP 450 DI 10.1016/0010-4361(93)90253-5 PG 4 WC Materials Science, Composites SC Materials Science GA LG744 UT WOS:A1993LG74400009 ER PT J AU KIM, HD LIU, NS AF KIM, HD LIU, NS TI A TIME-ACCURATE HIGH-RESOLUTION TVD SCHEME FOR SOLVING THE NAVIER-STOKES EQUATIONS SO COMPUTERS & FLUIDS LA English DT Article ID DIFFERENCE AB A TVD scheme has been developed and incorporated into an existing time-accurate high-resolution Navier-Stokes code. The accuracy and the robustness of the resulting solution procedure have been assessed by performing many calculations in four different areas: shock-tube flows; regular shock reflection; supersonic boundary layer, and shock-boundary layer interactions. These numerical results compare well with the corresponding exact solutions or experimental data. C1 NASA,LEWIS RES CTR,MS-5-11,CLEVELAND,OH 44135. NR 8 TC 6 Z9 6 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD JUL-SEP PY 1993 VL 22 IS 4-5 BP 517 EP 528 DI 10.1016/0045-7930(93)90023-3 PG 12 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA LN724 UT WOS:A1993LN72400009 ER PT J AU TUNG, C MCALISTER, KW WANG, CM AF TUNG, C MCALISTER, KW WANG, CM TI UNSTEADY AERODYNAMIC BEHAVIOR OF AN AIRFOIL WITH AND WITHOUT A SLAT SO COMPUTERS & FLUIDS LA English DT Article AB Unsteady flow behavior and load characteristics of a 2-D VR-7 airfoil with and without a leading-edge slat were studied in the water tunnel of the Aeroflightdynamics Directorate, NASA Ames Research Center. Both airfoils were oscillated sinusoidally between 5-degrees and 25-degrees at Re = 200,000 to obtain the unsteady lift, drag and pitching moment data. A fluorescent dye was released from an orifice located at the leading edge of the airfoil for the purpose of visualizing the boundary layer and wake flow. The flow field and load predictions of an incompressible Navier-Stokes code based on a velocity-vorticity formulation were compared with the test data. The test and predictions both confirm that the slatted VR-7 airfoil delays both static and dynamic stall as compared to the VR-7 airfoil alone. C1 GEORGIA INST TECHNOL,SCH AEROSP ENGN,ATLANTA,GA 30332. RP TUNG, C (reprint author), NASA,AMES RES CTR,AVSCOM,US ARMY AEROFLIGHTDYNAM DIRECTORATE,MOFFETT FIELD,CA 94035, USA. NR 9 TC 5 Z9 5 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD JUL-SEP PY 1993 VL 22 IS 4-5 BP 529 EP 547 DI 10.1016/0045-7930(93)90024-4 PG 19 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA LN724 UT WOS:A1993LN72400010 ER PT J AU ISHII, K KUWAHARA, K LIU, CH AF ISHII, K KUWAHARA, K LIU, CH TI NAVIER-STOKES CALCULATIONS FOR VORTEX RINGS IN AN UNBOUNDED DOMAIN SO COMPUTERS & FLUIDS LA English DT Article ID FILAMENT; MOTION; DECAY; CORE AB A computational code for the vorticity-potential method is developed for a three-dimensional bounded vorticity field. The evaluation of the boundary data for the vector potential in the code is improved so that the numerical solution simulates that in an unbounded domain to a high order. The time evolution of two vortex rings and that of an elliptic ring are investigated with this code. The cut-and-connect phenomena of vortex rings are successfully captured. The results are compared with those of asymptotic theory and the experiment. They also highlight the need for additional theoretical and numerical investigations. C1 INST SPACE & ASTRONAUT SCI,KANAGAWA 232,JAPAN. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP ISHII, K (reprint author), INST COMPUTAT FLUID DYNAM,1-22-3 HARAMACHI,MEGORO KU,TOKYO 152,JAPAN. NR 19 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD JUL-SEP PY 1993 VL 22 IS 4-5 BP 589 EP 605 DI 10.1016/0045-7930(93)90027-7 PG 17 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA LN724 UT WOS:A1993LN72400013 ER PT J AU LIU, CH KANDIL, OA KANDIL, HA AF LIU, CH KANDIL, OA KANDIL, HA TI NUMERICAL-SIMULATION AND PHYSICAL ASPECTS OF SUPERSONIC VORTEX BREAKDOWN SO COMPUTERS & FLUIDS LA English DT Article ID FLOW AB Existing numerical simulations and physical aspects of subsonic and supersonic vortex-breakdown modes are reviewed. The solution to the problem of supersonic vortex breakdown is emphasized in this paper and carried out with the full Navier-Stokes equations for compressible flows. Numerical simulations of vortex-breakdown modes are presented in bounded and unbounded domains. The effects of different types of downstream-exit boundary conditions are studied and discussed. C1 OLD DOMINION UNIV,DEPT MECH ENGN & MECH,NORFOLK,VA 23529. RP LIU, CH (reprint author), NASA,LANGLEY RES CTR,COMPUTAT AERODYNAM BRANCH,MS 128,HAMPTON,VA 23681, USA. NR 26 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD JUL-SEP PY 1993 VL 22 IS 4-5 BP 607 EP 622 DI 10.1016/0045-7930(93)90028-8 PG 16 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA LN724 UT WOS:A1993LN72400014 ER PT J AU KORDULLA, W LIU, CH AF KORDULLA, W LIU, CH TI ENHANCED PHYSICAL UNDERSTANDING OF FLUID-MECHANICS THROUGH A COMBINATION OF COMPUTATION AND EXPERIMENT - PREFACE SO COMPUTERS & FLUIDS LA English DT Editorial Material RP KORDULLA, W (reprint author), NASA,LANGLEY RES CTR,COMPUTAT AERODYNAM BRANCH,MS 128,HAMPTON,VA 23681, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD JUL-SEP PY 1993 VL 22 IS 4-5 BP R7 EP R8 DI 10.1016/0045-7930(93)90015-2 PG 2 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA LN724 UT WOS:A1993LN72400001 ER PT J AU JAGGI, S QUATTROCHI, DA LAM, NSN AF JAGGI, S QUATTROCHI, DA LAM, NSN TI IMPLEMENTATION AND OPERATION OF 3 FRACTAL MEASUREMENT ALGORITHMS FOR ANALYSIS OF REMOTE-SENSING DATA SO COMPUTERS & GEOSCIENCES LA English DT Article DE FRACTAL MEASUREMENT; REMOTE SENSING; LINE-DIVIDER; ISARITHM; TRIANGULAR PRISM; VARIOGRAM ID TOPOGRAPHIC SURFACES; DIMENSIONS; SCALE AB Fractal geometry is increasingly becoming a useful tool for modeling natural phenomena. As an alternative to Euclidean concepts, fractals allow for a more accurate representation of the nature of complexity in natural boundaries and surfaces. The purpose of this paper is to introduce and implement three algorithms in C code for deriving fractal measurement from remotely sensed data. These three methods are: the line-divider method, the variogram method, and the triangular prism method. Remote-sensing data acquired by NASA's Calibrated Airborne Multispectral Scanner (CAMS) are used to compute the fractal dimension using each of the three methods. These data were obtained as a 30 m pixel spatial resolution over a portion of western Puerto Rico in January 1990. A description of the three methods, their implementation in PC-compatible environment, and some results of applying these algorithms to remotely sensed image data are presented. C1 NASA,ES42 GEORGE C MARSHALL SPACE FLIGHT CTR,DIV EARTH SCI & APPLICAT,HUNTSVILLE,AL 35812. LOCKHEED ENGN & SCI CO,DEPT MAN SYST,HOUSTON,TX 77058. LOUISIANA STATE UNIV,DEPT GEOG & ANTHROPOL,BATON ROUGE,LA 70803. NR 23 TC 56 Z9 64 U1 1 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0098-3004 J9 COMPUT GEOSCI JI Comput. Geosci. PD JUL PY 1993 VL 19 IS 6 BP 745 EP 767 DI 10.1016/0098-3004(93)90048-A PG 23 WC Computer Science, Interdisciplinary Applications; Geosciences, Multidisciplinary SC Computer Science; Geology GA LH248 UT WOS:A1993LH24800001 ER PT J AU HO, JX HOLOWACHUK, EW NORTON, EJ TWIGG, PD CARTER, DC AF HO, JX HOLOWACHUK, EW NORTON, EJ TWIGG, PD CARTER, DC TI X-RAY AND PRIMARY STRUCTURE OF HORSE SERUM-ALBUMIN (EQUUS-CABALLUS) AT 0.27-NM RESOLUTION SO EUROPEAN JOURNAL OF BIOCHEMISTRY LA English DT Article ID AMINO-ACID SEQUENCE; DIABETIC BB-RAT; MESSENGER-RNA; NUCLEOTIDE-SEQUENCE; ALPHA-FETOPROTEIN; PLASMA-PROTEINS; CDNA; EXPRESSION; BINDING; REFINEMENT AB The amino-acid sequence and three-dimensional structure of equine serum albumin have been determined. The amino-acid sequence was deduced from cDNA isolated from equine liver. Comparisons of the primary structure of equine serum albumin with human serum albumin and bovine serum albumin reveal 76.1% and 73.9% sequence identity, respectively. The three-dimensional structure was determined crystallographically by the molecular-replacement method using molecular coordinates from the previously determined structure of human serum albumin, to a resolution of 0.27 nm. In accordance with the primary structure, the three-dimensional structures are highly conserved. There is a root-mean-square difference between alpha-carbons of the two structures of 0.201 nm. The association constants (Ka) for the binding of 2,3,5-triiodobenzoic acid were determined by ultrafiltration methods for equine and human serum albumins to be approximately 10(4)M-1 and 10(5)M-1, respectively. Crystallographic studies of equine serum albumin reveal two binding sites for 2,3,5-triiodobenzoic acid identical with those previously reported for human serum albumin which are located within subdomains IIA and IIIA. Details and comparisons of the binding chemistry are discussed. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES76 BIOPHYS BRANCH,HUNTSVILLE,AL 35812. MARY IMOGENE BASSETT HOSP,RES INST,COOPERSTOWN,NY 13326. NR 56 TC 80 Z9 83 U1 0 U2 2 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0014-2956 J9 EUR J BIOCHEM JI Eur. J. Biochem. PD JUL 1 PY 1993 VL 215 IS 1 BP 205 EP 212 DI 10.1111/j.1432-1033.1993.tb18024.x PG 8 WC Biochemistry & Molecular Biology SC Biochemistry & Molecular Biology GA LM144 UT WOS:A1993LM14400025 PM 8344282 ER PT J AU LIEBOWITZ, J LIGHTFOOT, P AF LIEBOWITZ, J LIGHTFOOT, P TI SCHEDULING APPROACHES IN EXPERT SYSTEMS - A STUDY OF THEIR APPLICABILITY SO EXPERT SYSTEMS WITH APPLICATIONS LA English DT Article AB Expert scheduling systems are being used in a variety of domains, including manufacturing, personnel, aerospace, and military applications. Very little work has been done in determining when it is most appropriate to use a particular scheduling approach in an expert system. This paper addresses this area, placing special emphasis on matching scheduling techniques to requirements in the NASA (National Aeronautics and Space Administration) mission planning arena. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP LIEBOWITZ, J (reprint author), GEORGE WASHINGTON UNIV,DEPT MANAGEMENT SCI,WASHINGTON,DC 20052, USA. NR 22 TC 4 Z9 4 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0957-4174 J9 EXPERT SYST APPL JI Expert Syst. Appl. PD JUL-SEP PY 1993 VL 6 IS 3 BP 231 EP 235 DI 10.1016/0957-4174(93)90052-8 PG 5 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic; Operations Research & Management Science SC Computer Science; Engineering; Operations Research & Management Science GA LH380 UT WOS:A1993LH38000003 ER PT J AU DEMARTINI, EE AF DEMARTINI, EE TI MODELING THE POTENTIAL OF FISHERY RESERVES FOR MANAGING PACIFIC CORAL-REEF FISHES SO FISHERY BULLETIN LA English DT Article ID MARINE RESERVE; CONSERVATION; ASSEMBLAGE; COMMUNITIES; POPULATION; ABUNDANCE; ISLAND; DESIGN; COAST AB The potential use of marine fishery reserves (MFRs) for managing fisheries on tropical Pacific coral reefs was assessed with an extension of the Beverton-Holt model. The effects of year-round fishery closures on harvests in adjacent, exploited areas were evaluated. Potential changes in spawning stock biomass per recruit (SSB/R) and yield per recruit (Y/R), when varying fractions of exploitable reef area were closed to fishing, were estimated from published data, approximated natural and fishing mortality rates, size- and maturity-at-age distributions, and ''transfer'' (emigration and immigration) rates. For select cases, fundamental transfer rates were adjusted for possible density-dependent emigration from closed areas as relative densities decreased in surrounding non-closed areas because of continued fishing. Three hypothetical ''fish types'' were constructed, bracketing the likely extremes in fundamental transfer rates and related life-history parameters of Pacific coral reef fishes: a small-bodied, fast-growing and short-lived, strongly philopatric species of damselfish was contrasted with a large-bodied, relatively slow-growing, long-lived, vagile species of jack. A ''surgeonfish'' type was used to represent intermediate parameter values. Simulations corroborate previous observations that MFRs contribute little, if anything, towards increasing Y/R. Results for the highly vagile jack confirm that rapid transfer rates will negate potential gains in SSB/R resulting from closures. At the opposite extreme, small reef philopatriots like damselfishes would almost never be harvested, because of negligible transfer rates, unless the MFR was periodically opened to fishing. The simulations suggest that the SSB/R of the surgeonfish type is the most likely to benefit from MFRs, because moderate vagility allows biomass to accumulate within the closure despite harvesting in the non-closed area. Results further suggest that growth rate, fishing effort in the non-closed (open) area, natural mortality, and maturity and harvesting schedules importantly influence the potential of MFRs to augment SSB when transfer rates are low to moderate. RP DEMARTINI, EE (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 47 TC 178 Z9 180 U1 2 U2 27 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1993 VL 91 IS 3 BP 414 EP 427 PG 14 WC Fisheries SC Fisheries GA MD449 UT WOS:A1993MD44900002 ER PT J AU HUMPHREYS, RL CROSSLER, MA ROWLAND, CM AF HUMPHREYS, RL CROSSLER, MA ROWLAND, CM TI USE OF A MONOGENEAN GILL PARASITE AND FEASIBILITY OF CONDITION INDEXES FOR IDENTIFYING NEW RECRUITS TO A SEAMOUNT POPULATION OF ARMORHEAD PSEUDOPENTACEROS-WHEELERI (PENTACEROTIDAE) SO FISHERY BULLETIN LA English DT Article ID NORTH PACIFIC-OCEAN AB Recruitment of individuals from the epipelagic phase to the demersal armorhead Pseudopentaceros wheeleri population at Southeast (SE) Hancock Seamount has typically been recognized by the influx of fish with a high fatness index (FI; body depth relative to fork length). Reliance on this index was dictated by the peculiarity of the sea-mount life history stage in which armorhead cease somatic growth soon after recruitment to the seamount and FI declines during seamount residence until death. Limited sampling opportunities and variability in FI at the time of recruitment preclude the exclusive use of FI as a means of identifying newly arrived recruits among recruits-of-the-year and hence the timing of annual recruitment. Settlement and recruitment to the seamount population are synonymous. Efforts to develop a method of identifying new recruits were initiated by an examination of epipelagic and seamount (SE Hancock) armorhead for differences in macroparasites as well as hepatosomatic and visceral fat-somatic indices. Of the two condition indices, the hepatosomatic index held the most potential but was considered too labile because pre-recruits probably experience decreases that vary according to energetic demands during seamount migration. The monogenean gill parasite Microcotyle macropharynx was highly prevalent among seamount individuals in all sampling periods but absent from epipelagics. Based on probable rapid infection and maturation, identification of new recruits was based on the absence of mature M. macrophaynx. Results indicate that significant new recruitment occurred only during the late spring to midsummer sampling periods, and the mean FI of new seamount recruits was lower than that of comparable size epipelagics. RP HUMPHREYS, RL (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 20 TC 10 Z9 10 U1 0 U2 5 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1993 VL 91 IS 3 BP 455 EP 463 PG 9 WC Fisheries SC Fisheries GA MD449 UT WOS:A1993MD44900005 ER PT J AU ZOLENSKY, M BARRETT, R BROWNING, L AF ZOLENSKY, M BARRETT, R BROWNING, L TI MINERALOGY AND COMPOSITION OF MATRIX AND CHONDRULE RIMS IN CARBONACEOUS CHONDRITES SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID ACCRETIONARY DUST MANTLES; AQUEOUS ALTERATION; CM CHONDRITES; CHEMICAL VARIATIONS; SURFACE CONDITIONS; ALLENDE METEORITE; TYPE-3 CHONDRITES; CI CHONDRITES; PARENT BODIES; SOLAR NEBULA AB The degree of compositional variation of fine-grained minerals displayed by the members within any carbonaceous chondrite group (i.e., CI, CM, CV, CR) is a direct reflection of the range of aqueous alteration assemblages present. Matrix and fine-grained chondrule rims within any particular carbonaceous chondrite are mineralogically nearly identical to one another, but not necessarily similar in bulk elemental composition, even though they have subsequently experienced post-accretional secondary processing (aqueous alteration) under identical conditions. This may indicate preferential alteration of one component, brecciation, exchange of components between rims and matrix, and/or accretion of matrix and rims from mineralogically or compositionally distinct materials. We propose that CO chondrites experienced parent body conditions of low f(O2), low water/rock ratios, and temperatures below 50-degrees-C. CR chondrites experienced higher water/rock ratios, potentially higher temperatures (less-than-or-equal-to 150-degrees-C), and a wide range of f(O2). The alteration mineralogy of CV chondrites indicates water/rock ratios at the high end (at least) of the range for CR chondrites, Essebi, and MAC 87300. CM chondrites experienced temperatures below 50-degrees-C, low f(O2) and low water/rock ratios, except EET 83334, which probably experienced relatively higher f(O2), and B-7904 and Y-86720, which experienced postalteration temperatures in the range 500-700-degrees-C. Most CI chondrites experienced temperatures between 50 and 150-degrees-C, relatively high water/rock ratios, and variable f(O2) with a late-stage increase in the latter, due possibly to brecciation and consequent release of methane. Y-82162 witnessed post-alteration heating, possibly as high as 400-degrees-C. C1 LOCKHEED LESCO,HOUSTON,TX 77058. LUNAR & PLANETARY INST,HOUSTON,TX 77058. RP ZOLENSKY, M (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV SOLAR SYST EXPLORAT,HOUSTON,TX 77058, USA. NR 78 TC 274 Z9 274 U1 4 U2 26 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD JUL PY 1993 VL 57 IS 13 BP 3123 EP 3148 DI 10.1016/0016-7037(93)90298-B PG 26 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LM788 UT WOS:A1993LM78800015 ER PT J AU CHYBA, CF AF CHYBA, CF TI THE VIOLENT ENVIRONMENT OF THE ORIGIN OF LIFE - PROGRESS AND UNCERTAINTIES SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article; Proceedings Paper CT SYMP ON SURVIVABILITY OF ORGANIC MATTER AT HIGH TEMPERATURES : IMPLICATIONS FOR LIFE, AT THE 1991 ANNUAL MEETING OF THE GEOLOGICAL SOC OF AMERICA CY OCT 20, 1991 CL SAN DIEGO, CA SP GEOL SOC AMER, ORGANIC GEOCHEM DIV, AMER CHEM SOC, GEOCHEM DIV, UNOCAL ID SOLAR-SYSTEM; EARLY EARTH; ORGANIC-MOLECULES; SHOCK SYNTHESIS; IMPACTS; EVOLUTION; DELIVERY; MATTER; RECORD; ATMOSPHERE AB Dating of terrestrial fossils and returned lunar samples reveals that the origin of life on Earth occurred not in a quiescent, peaceful environment, but rather in a violent, impact-ridden one. This realization has important consequences. On the one hand, sufficiently large and fast impactors can erode planetary atmospheres, and the very largest of these may have sterilized the surface of the Earth. In this regard, deep-sea hydrothermal vents become especially interesting for the history of early life, as they provide an environment protected against all but the greatest impact devastation. At the same time, impactors would have been delivering key biogenic elements (such as carbon and nitrogen) to Earth's surface, and (with much greater difficulty) intact organic molecules as well. Estimates of the various sources of prebiotic organics suggest that the heavy bombardment either produced or delivered quantities of organics comparable to those produced by other energy sources. However, substantial uncertainties exist. After reviewing the current understanding of the role of the heavy bombardment in the origins of life, a number of remaining key uncertainties are considered, and attempts are made to both quantify their magnitude and point to means of resolving them. RP CHYBA, CF (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 66 TC 62 Z9 61 U1 4 U2 21 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD JUL PY 1993 VL 57 IS 14 BP 3351 EP 3358 DI 10.1016/0016-7037(93)90543-6 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LP794 UT WOS:A1993LP79400010 ER PT J AU PINELLI, TE BARCLAY, RO KENNEDY, JM AF PINELLI, TE BARCLAY, RO KENNEDY, JM TI THE UNITED-STATES-GOVERNMENT TECHNICAL REPORT AND THE TRANSFER OF FEDERALLY FUNDED AEROSPACE R-AND-D SO GOVERNMENT PUBLICATIONS REVIEW LA English DT Article ID TECHNOLOGY POLICY AB This article discusses the U.S. government technical report and the transfer of federally funded aerospace research and development in a conceptual framework of the federal government as a producer of scientific and technical information. The article summarizes current literature and research and discusses U.S. government technical report use and the importance of using data obtained from the NASA/DoD Aerospace Knowledge Diffusion Research Project. The authors make a case for changing existing U.S. technology policy and present a research agenda for the U.S. government technical report. C1 RENSSELAER POLYTECH INST,DEPT LANGUAGE LITERATURE & COMMUN,TROY,NY 12180. INDIANA UNIV,CTR SURVEY RES,BLOOMINGTON,IN 47405. RP PINELLI, TE (reprint author), NASA,LANGLEY RES CTR,DIV RES INFORMAT & APPLICAT,DOD AEROSP KNOWLEDGE DIFFUS RES PROJECT,HAMPTON,VA 23681, USA. NR 59 TC 1 Z9 1 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0277-9390 J9 GOV PUBL REV PD JUL-AUG PY 1993 VL 20 IS 4 BP 393 EP 411 DI 10.1016/0277-9390(93)90034-M PG 19 WC Information Science & Library Science SC Information Science & Library Science GA LP107 UT WOS:A1993LP10700002 ER PT J AU JONES, JA AF JONES, JA TI SORPTION REFRIGERATION RESEARCH AT JPL NASA SO HEAT RECOVERY SYSTEMS & CHP LA English DT Article; Proceedings Paper CT SYMP ON SOLID SORPTION REFRIGERATION CY NOV 18-20, 1992 CL FRENCH RES & SPACE DEPT, PARIS, FRANCE SP EUROPEAN COMMUNITY, FRENCH AGCY ENERGY & ENVIRONM, GAZ FRANCE, CNRS, PIRSEM HO FRENCH RES & SPACE DEPT AB Since 1979, long-life, reliable heat-powered sorption refrigeration systems have been developed for spacecraft use at the Jet Propulsion Laboratory (JPL). JPL has successfully built and tested a series of cryogenic sorption refrigeration systems for spacecraft sensor cooling and is presently assembling a -263-degrees-C (10K) hydride sorption refrigerator, which will fly on the Space Shuttle in 1994. With the addition of novel regenerative heating techniques, this same technology has more recently been applied to design high efficiency, ground-based adsorption heat pumps. Using actual sorption isotherm data and detailed analytic thermal computer models, analysis has predicted that the cooling and heating COPs will be significantly better than for any other single stage, heat-powered heat pump. Specifically the cooling COP (COP(c)) with the new regenerative system using ammonia is predicted to be as high as about 1.16. Recent tests on a single carbon sorbent canister compressor have been performed with R22, R134a, and ammonia. Transient thermal response of the sorption compressor has compared well with computer predictions. With ammonia, the total amount of average cooling from the 0.51 kg bed of carbon has been measured to be about 1038 Btu h-1 (304 W) for a 6 min full cycle including both heating and cooling. RP JONES, JA (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 9 Z9 10 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0890-4332 J9 HEAT RECOV SYST CHP JI Heat Recovery Syst. CHP PD JUL PY 1993 VL 13 IS 4 BP 363 EP 371 DI 10.1016/0890-4332(93)90062-Z PG 9 WC Thermodynamics; Energy & Fuels; Engineering, Mechanical; Mechanics SC Thermodynamics; Energy & Fuels; Engineering; Mechanics GA LK691 UT WOS:A1993LK69100013 ER PT J AU WURZ, P BOCHSLER, P GHIELMETTI, AG SHELLEY, EG HERRERO, F SMITH, MF AF WURZ, P BOCHSLER, P GHIELMETTI, AG SHELLEY, EG HERRERO, F SMITH, MF TI REMOTE IMAGING OF ION DISTRIBUTIONS USING LOW-ENERGY NEUTRAL ATOMS SO HELVETICA PHYSICA ACTA LA English DT Article; Proceedings Paper CT 1993 SPRING MEETING OF THE SOC-SUISSE-DE-PHYSIQUE CY MAR 24-26, 1993 CL NEUCHATEL, SWITZERLAND SP SOC SUISSE PHYS AB The scope of the neutral atom imaging instrument on the proposed HI-LITE mission is to study the instantaneous global distribution of the low energy ion outflow from the high latitude auroral region, and its large scale temporal evolution with solar and geomagnetic activity by detecting neutral atoms, produced through charge exchange between the out flowing ions and the neutral atmosphere. The proposed instrument will record maps of energy and mass flux of the source region. For satisfactory performance, high ionization efficiency for the two species of principal interest, H and O, in the energy range of 10 eV to 300 eV is required. To achieve this, surface ionization will be employed, where a considerable fraction of the reflected primary atoms will be negatively ionized. C1 LOCKHEED MISSILES & SPACE CO INC,PALO ALTO RES LAB,DEPT 9120,PALO ALTO,CA 94304. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP WURZ, P (reprint author), UNIV BERN,INST PHYS,CH-3012 BERN,SWITZERLAND. NR 6 TC 1 Z9 1 U1 0 U2 0 PU BIRKHAUSER VERLAG AG PI BASEL PA PO BOX 133 KLOSTERBERG 23, CH-4010 BASEL, SWITZERLAND SN 0018-0238 J9 HELV PHYS ACTA JI Helv. Phys. Acta PD JUL PY 1993 VL 66 IS 4 BP 445 EP 446 PG 2 WC Physics, Multidisciplinary SC Physics GA LQ316 UT WOS:A1993LQ31600025 ER PT J AU BELL, JF CRISP, D AF BELL, JF CRISP, D TI GROUNDBASED IMAGING SPECTROSCOPY OF MARS IN THE NEAR-INFRARED - PRELIMINARY-RESULTS SO ICARUS LA English DT Article ID ACCURATE CALCULATED TABULATIONS; MARTIAN ATMOSPHERE; REFLECTANCE SPECTROSCOPY; RADIATIVE-TRANSFER; TEMPERATURE-RANGE; SURFACE REGIONS; ISM EXPERIMENT; WATER-VAPOR; H2O; CO2 C1 UNIV HAWAII,SCH OCEAN & EARTH SCI & TECHNOL,DIV PLANETARY GEOSCI,HONOLULU,HI 96822. JET PROP LAB,PASADENA,CA 91109. NR 67 TC 38 Z9 38 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1993 VL 104 IS 1 BP 2 EP 19 DI 10.1006/icar.1993.1078 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LQ898 UT WOS:A1993LQ89800001 ER PT J AU PLESCIA, JB AF PLESCIA, JB TI AN ASSESSMENT OF VOLATILE RELEASE FROM RECENT VOLCANISM IN ELYSIUM, MARS SO ICARUS LA English DT Article ID COLUMBIA RIVER BASALT; LAVA FLOW MORPHOLOGY; KILAUEA VOLCANO; CLIMATIC-CHANGE; CARBON-DIOXIDE; MARTIAN PALEOCLIMATE; CHEMICAL-COMPOSITION; TERRESTRIAL PLANETS; ALBA-PATERA; ERUPTION RP PLESCIA, JB (reprint author), JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. RI Plescia, Jeffrey/B-7738-2016 NR 104 TC 25 Z9 25 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1993 VL 104 IS 1 BP 20 EP 32 DI 10.1006/icar.1993.1079 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LQ898 UT WOS:A1993LQ89800002 ER PT J AU PODOLAK, M PRIALNIK, D BUNCH, TE CASSEN, P REYNOLDS, R AF PODOLAK, M PRIALNIK, D BUNCH, TE CASSEN, P REYNOLDS, R TI SECONDARY PROCESSING OF CHONDRULES AND REFRACTORY INCLUSIONS (CAIS) BY GASDYNAMIC HEATING SO ICARUS LA English DT Article ID SOLAR NEBULA; ORDINARY CHONDRITES; RIMS; PLANETESIMALS; ATMOSPHERES; HISTORY; EVENTS C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP PODOLAK, M (reprint author), TEL AVIV UNIV,DEPT GEOPHYS & PLANETARY SCI,IL-69978 TEL AVIV,ISRAEL. NR 40 TC 9 Z9 9 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1993 VL 104 IS 1 BP 97 EP 109 DI 10.1006/icar.1993.1085 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LQ898 UT WOS:A1993LQ89800008 PM 11540090 ER PT J AU SCHUTTE, WA ALLAMANDOLA, LJ SANDFORD, SA AF SCHUTTE, WA ALLAMANDOLA, LJ SANDFORD, SA TI AN EXPERIMENTAL-STUDY OF THE ORGANIC-MOLECULES PRODUCED IN COMETARY AND INTERSTELLAR ICE ANALOGS BY THERMAL FORMALDEHYDE REACTIONS SO ICARUS LA English DT Article ID TIME-DEPENDENT CHEMISTRY; MICRON ABSORPTION; GRAIN MANTLES; MASS-SPECTRA; HALLEY; CO; CLOUDS; GAS; POLYOXYMETHYLENE; IDENTIFICATION C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 51 TC 154 Z9 154 U1 2 U2 23 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1993 VL 104 IS 1 BP 118 EP 137 DI 10.1006/icar.1993.1087 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LQ898 UT WOS:A1993LQ89800010 PM 11540089 ER PT J AU HOBAN, S AF HOBAN, S TI SERENDIPITOUS IMAGES OF METHANOL IN COMET LEVY (1990-XX) SO ICARUS LA English DT Note ID EMISSION FEATURE RP HOBAN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,CODE 693,GREENBELT,MD 20771, USA. NR 13 TC 1 Z9 1 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1993 VL 104 IS 1 BP 149 EP 151 DI 10.1006/icar.1993.1089 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LQ898 UT WOS:A1993LQ89800012 ER PT J AU UPADHYAY, T COTTERILL, S DEATON, AW AF UPADHYAY, T COTTERILL, S DEATON, AW TI AUTONOMOUS GPS/INS NAVIGATION EXPERIMENT FOR SPACE TRANSFER VEHICLE SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article AB An experiment is described to validate the concept of developing an autonomous integrated spacecraft navigation system using onboard Global Positioning System (GPS) and Inertial Navigation System (INS) measurements. Previous work by the authors [1, 2] have demonstrated the feasibility of integrating GPS measurements with INS measurements to provide a total improvement in spacecraft navigation performance, i.e., improvement in position, velocity and attitude informatiom An important aspect of this research is the automatic real-time reconfiguration capability of the system designed to respond to changes in a spacecraft mission under the control of an expert system. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,DIV SYST ANAL,FLIGHT MECH BRANCH,HUNTSVILLE,AL 35812. RP UPADHYAY, T (reprint author), MAYFLOWER COMMUN CO,80 MAIN ST,READING,MA 01867, USA. NR 16 TC 18 Z9 24 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD JUL PY 1993 VL 29 IS 3 BP 772 EP 785 DI 10.1109/7.220929 PG 14 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA LM176 UT WOS:A1993LM17600016 ER PT J AU MENON, PKA CHATTERJI, GB SRIDHAR, B AF MENON, PKA CHATTERJI, GB SRIDHAR, B TI ELECTROOPTICAL NAVIGATION FOR AIRCRAFT SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID ROTORCRAFT AB Low altitude flight is extremely demanding on the rotorcraft pilots. This fact has motivated the research in automating various components of low altitude rotorcraft flight operations. Concurrent with the development of guidance laws, efforts are underway to develop systems for locating the terrain and the obstacles using inputs from passive electro-optical sensors such as TV cameras and infrared imagers. A passive obstacle location algorithm that uses image sequences from cameras undergoing translational and rotational motion is developed. The algorithm is in a general form and can operate in multicamera imaging environments. Performance results using an image sequence from an airborne camera are given. C1 GEORGIA INST TECHNOL,SCH AEROSP ENGN,ATLANTA,GA 30332. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 12 TC 4 Z9 6 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD JUL PY 1993 VL 29 IS 3 BP 825 EP 833 DI 10.1109/7.220933 PG 9 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA LM176 UT WOS:A1993LM17600020 ER PT J AU RICHARD, MA BHASIN, KB CLASPY, PC AF RICHARD, MA BHASIN, KB CLASPY, PC TI SUPERCONDUCTING MICROSTRIP ANTENNAS - AN EXPERIMENTAL COMPARISON OF 2 FEEDING METHODS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID THIN-FILMS; PERMITTIVITY; ATTENUATION; SUBSTRATE AB The recent discovery of high-temperature superconductors (HTS's) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. In this paper, two methods for feeding HTS microstrip antennas at K and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gap-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In ma case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP RICHARD, MA (reprint author), CASE WESTERN RESERVE UNIV,DEPT ELECT ENGN & APPL PHYS,CLEVELAND,OH 44106, USA. NR 24 TC 37 Z9 38 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD JUL PY 1993 VL 41 IS 7 BP 967 EP 974 DI 10.1109/8.237630 PG 8 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA LY048 UT WOS:A1993LY04800018 ER PT J AU MILEANT, A HINEDI, S AF MILEANT, A HINEDI, S TI ON THE EFFECTS OF PHASE JITTER ON QPSK LOCK DETECTION SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Letter AB We describe the performance of a QPSK lock detector taking into account the degradation due to carrier phase jitter. Such an analysis is necessary for accurate performance prediction purposes in scenarios where both the loop SNR is low and the estimation period is short. The derived formulas are applicable to several QPSK loops and are verified using computer simulations. RP MILEANT, A (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 7 TC 9 Z9 10 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD JUL PY 1993 VL 41 IS 7 BP 1043 EP 1046 DI 10.1109/26.231935 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA LV610 UT WOS:A1993LV61000008 ER PT J AU JACKSON, TJ LEVINE, DM GRIFFIS, AJ GOODRICH, DC SCHMUGGE, TJ SWIFT, CT ONEILL, PE AF JACKSON, TJ LEVINE, DM GRIFFIS, AJ GOODRICH, DC SCHMUGGE, TJ SWIFT, CT ONEILL, PE TI SOIL-MOISTURE AND RAINFALL ESTIMATION OVER A SEMIARID ENVIRONMENT WITH THE ESTAR MICROWAVE RADIOMETER SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 12TH IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMP ( IGARSS 92 ) CY MAY 26-29, 1992 CL LEAGUE CITY, TX SP IEEE, GEOSCI & REMOTE SENSING SOC, UNION RADIO SCI ENGINEERS ID EMISSION AB The application of an airborne electronically steered thinned array L-band radiometer (ESTAR) for soil moisture mapping was investigated over the semiarid rangeland Walnut Gulch Watershed located in southeastern Arizona. During the experiment, antecedent rainfall and evaporation were very different and resulted in a wide range of soil moisture conditions. The high spatial variability of rainfall events within this region resulted in moisture conditions with distinct spatial patterns. Analysis showed a correlation between the decrease in brightness temperature after a rainfall and the amount of rain. The sensor's performance was verified using two approaches. First, the microwave data were used in conjunction with a microwave emission model to predict soil moisture. These predictions were compared to ground observations of soil moisture. A second verification was possible using an extensive data set collected the previous year at the same site with a conventional L-band push broom microwave radiometer (PBMR). Both tests showed that the ESTAR is capable of providing soil moisture with the same level of accuracy as existing systems. ESTAR instruments have the potential to satisfy application data requirements from spaceborne platforms. C1 NASA,GODDARD SPACE FLIGHT CTR,MICROWAVE SENSORS BRANCH,GREENBELT,MD 20771. KAMAN AEROSP CORP,TUCSON,AZ 85706. UNIV MASSACHUSETTS,MICROWAVE REMOTE SENSING LAB,AMHERST,MA 01003. USDA ARS,SW WATERSHED RES CTR,TUCSON,AZ 85719. NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,GREENBELT,MD 20771. RP JACKSON, TJ (reprint author), USDA ARS,BELTSVILLE AGR RES CTR,HYDROL LAB,BELTSVILLE,MD 20705, USA. RI Goodrich, David/B-1763-2009; O'Neill, Peggy/D-2904-2013 OI Goodrich, David/0000-0001-7735-1448; NR 9 TC 55 Z9 56 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1993 VL 31 IS 4 BP 836 EP 841 DI 10.1109/36.239906 PG 6 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA ME122 UT WOS:A1993ME12200011 ER PT J AU DAVIS, DT CHEN, ZX HWANG, JN CHANG, ATC TSANG, L AF DAVIS, DT CHEN, ZX HWANG, JN CHANG, ATC TSANG, L TI RETRIEVAL OF SNOW PARAMETERS BY ITERATIVE INVERSION OF A NEURAL-NETWORK SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 12TH IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMP ( IGARSS 92 ) CY MAY 26-29, 1992 CL LEAGUE CITY, TX SP IEEE, GEOSCI & REMOTE SENSING SOC, UNION RADIO SCI ENGINEERS ID MEDIA AB The inversion of snow parameters from passive microwave remote sensing measurements is performed based on an iterative inversion of a neural network (NN) trained with a dense media multiple scattering model. Inversion of four parameters is performed from five brightness temperatures. The four parameters are: mean-grain size of ice particles in snow, snow density, snow temperature, and snow depth. Iterative inversion of a data driven forward NN model is justified on a theoretical and methodological basis. We perform an error analysis, comparing iterative inversion of a forward model with the use of an explicit inverse for the retrieval of independent snow parameters from their corresponding measurements. The NN iterative inversion algorithm is further illustrated by reconstructing a synthetic terrain of snow parameters from their corresponding measurements, inverting all four parameters simultaneously. The reconstructed parameter contours are in good agreement with the original synthetic parameter contours. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,GREENBELT,MD 20771. RP DAVIS, DT (reprint author), UNIV WASHINGTON,DEPT ELECT ENGN,SEATTLE,WA 98195, USA. NR 21 TC 43 Z9 52 U1 2 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1993 VL 31 IS 4 BP 842 EP 852 DI 10.1109/36.239907 PG 11 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA ME122 UT WOS:A1993ME12200012 ER PT J AU WANG, JR BONCYK, WC SHARMA, AK AF WANG, JR BONCYK, WC SHARMA, AK TI WATER-VAPOR PROFILING OVER OCEAN SURFACE FROM AIRBORNE 90 AND 183 GHZ RADIOMETRIC MEASUREMENTS UNDER CLEAR AND CLOUDY CONDITIONS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 12TH IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMP ( IGARSS 92 ) CY MAY 26-29, 1992 CL LEAGUE CITY, TX SP IEEE, GEOSCI & REMOTE SENSING SOC, UNION RADIO SCI ENGINEERS ID MICROWAVE RADIOMETRY; LIQUID WATER; WIND-SPEED; RETRIEVAL; SSM/I AB Radiometric measurements at 90 GHz and three sideband frequencies near the water vapor absorption Line of 183.3 GHz were made with the advanced microwave moisture sounder (AMMS) aboard the NASA DC-8 aircraft over some regions of the Pacific Ocean during November 1989. These measurements were used to retrieve atmospheric water vapor profiles over ocean surface using the algorithm developed by Wilheit. The algorithm incorporates a mechanism to estimate cloud liquid water when the estimated relative humidity is greater than 95%. The results were compared with the estimated values from the measurements of special sensor microwave imager (SSMI) and TIROS operational vertical sounder (TOVS). The water vapor profiles estimated from AMMS are generally higher at low altitudes and lower at high altitudes compared to those from the TOVS measurements. Values of total precipitable water estimated from the AMMS and SSM/I are in general agreement. Cloud liquid water is retrieved from both AMMS and SSM/I measurements over the same general regions. The water vapor profiles retrieved from the AMMS show more fluctuations in these regions; frequently, there is a deficiency of water vapor at low altitudes. Most likely, the AMMS with only four channels of measurements cannot retrieve both water vapor and cloud information with authority. C1 ST SYST CORP,LANHAM,MD 20706. RP WANG, JR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 14 TC 6 Z9 6 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1993 VL 31 IS 4 BP 853 EP 859 DI 10.1109/36.239908 PG 7 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA ME122 UT WOS:A1993ME12200013 ER PT J AU RIGNOT, EJM VANZYL, JJ AF RIGNOT, EJM VANZYL, JJ TI CHANGE DETECTION TECHNIQUES FOR ERS-1 SAR DATA SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 12TH IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMP ( IGARSS 92 ) CY MAY 26-29, 1992 CL LEAGUE CITY, TX SP IEEE, GEOSCI & REMOTE SENSING SOC, UNION RADIO SCI ENGINEERS ID MICROWAVE AB Several techniques for detecting temporal changes in satellite synthetic aperture radar (SAR) imagery are compared using both theoretical predictions and spaceborne SAR data collected by the European first Remote Sensing Satellite, ERS-1. In a first set of techniques, changes are detected based on differences in the magnitude of the signal intensity between two dates. Ratioing of the multidate radar intensities is shown to be better adapted to the statistical characteristics of SAR data than subtracting, and works best when the number of looks is large. In a second set of techniques, changes are detected based on estimates of the temporal decorrelation of speckle. This method works best with one-look complex amplitude data, but can also be used with intensity data provided that the number of looks is small. The two techniques, ratioing of the signal intensity and decorrelation of speckle, are compared using actual SAR data collected by ERS-1. The results illustrate the viability as well as the complementary character of these techniques for detecting changes in the structural and dielectric properties of remotely sensed surfaces. Finally, change detection using the ratio method is applied to mosaics of repeat-pass SAR imagery to illustrate the potential of this method for monitoring applications at the regional scale. RP RIGNOT, EJM (reprint author), CALTECH,JET PROP LAB,RADAR SCI & ENGN SECT,PASADENA,CA 91109, USA. RI Mitchard, Edward/C-6346-2009; Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 19 TC 277 Z9 297 U1 3 U2 17 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1993 VL 31 IS 4 BP 896 EP 906 DI 10.1109/36.239913 PG 11 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA ME122 UT WOS:A1993ME12200018 ER PT J AU JIN, MY AF JIN, MY TI PREDICTION OF SAR FOCUS PERFORMANCE USING EPHEMERIS COVARIANCE SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 12TH IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMP ( IGARSS 92 ) CY MAY 26-29, 1992 CL LEAGUE CITY, TX SP IEEE, GEOSCI & REMOTE SENSING SOC, UNION RADIO SCI ENGINEERS AB Synthetic aperture radar (SAR) focus can be achieved based on either accurate ephemeris data or SAR processing parameters obtained from an autofocus process. For a SAR mapping project, a decision for choosing one approach must be made in the early phase of the system design. This requires a detailed analysis to predict the focus performance based on the predicted performance of the ephemeris data. For the Magellan project, this analysis is complicated by the facts that 1) the Magellan radar is operated in a burst mode and 2) the Magellan radar maps the surface of Venus from a highly elliptical orbit. In this paper, the analysis is general enough so that both the strip mapping mode SAR system and the burst mode SAR system are considered. The final result leads to a conclusion that the ephemeris data obtained from the Magellan navigation system provides sufficient accuracy for meeting the Magellan image resolution requirement. RP JIN, MY (reprint author), CALTECH,JET PROP LAB,RADAR SCI & ENGN SECT,PASADENA,CA 91109, USA. NR 5 TC 3 Z9 4 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1993 VL 31 IS 4 BP 914 EP 920 DI 10.1109/36.239915 PG 7 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA ME122 UT WOS:A1993ME12200020 ER PT J AU MILLER, JW GOODMAN, R SMYTH, P AF MILLER, JW GOODMAN, R SMYTH, P TI ON LOSS FUNCTIONS WHICH MINIMIZE TO CONDITIONAL EXPECTED VALUES AND POSTERIOR PROBABILITIES SO IEEE TRANSACTIONS ON INFORMATION THEORY LA English DT Letter DE OBJECTIVE FUNCTIONS; LOSS FUNCTIONS; PROBABILITY ESTIMATION AB A loss function, or objective function, is a function used to compare parameters when fitting a model to data. The loss function gives a distance between the model output and the desired output Two common examples are the squared-error loss function and the cross entropy loss function. It is well known that minimizing the mean-square error loss function is equivalent to minimizing the mean square difference between the model output and the expected value of the output given a particular input. This property of minimization to the expected value is formalized as ''P-admissibility.'' The necessary and sufficient conditions for P-admissibility, leading to a parametric description of all P-admissible loss functions are found. In particular, it is shown that two of the simplest members of this class of functions are the squared error and the cross entropy loss functions. One application of this work is in the choice of a loss function for training neural networks to provide probability estimates. C1 CALTECH,DEPT ELECT ENGN,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. RP MILLER, JW (reprint author), MICROSOFT RES,9S-1051,ONE MICROSOFT WAY,REDMOND,WA 98052, USA. NR 6 TC 21 Z9 21 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9448 J9 IEEE T INFORM THEORY JI IEEE Trans. Inf. Theory PD JUL PY 1993 VL 39 IS 4 BP 1404 EP 1408 DI 10.1109/18.243457 PG 5 WC Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MG075 UT WOS:A1993MG07500027 ER PT J AU EKROOT, L COVER, TM AF EKROOT, L COVER, TM TI THE ENTROPY OF MARKOV TRAJECTORIES SO IEEE TRANSACTIONS ON INFORMATION THEORY LA English DT Letter AB The idea of thermodynamic depth put forth by Lloyd and Pagels requires the computation of the entropy of Markov trajectories. Toward this end we consider an irreducible finite state Markov chain with transition matrix P and associated entropy rate H(X) = -SIGMA(i,j) mu(i)P(ij) log P(ij), where mu is the stationary distribution given by the solution of mu = muP. A trajectory T(ij) of the Markov chain is a path with initial state i, final state j, and no intervening states equal to j. We show that the entropy H(T(ii)) of the random trajectory originating and terminating in state i is given by H(T(ii)) = H(X)/mu(i). Thus the entropy of the random trajectory T(ii) is the product of the expected number of steps 1/mu(i) to return to state i and the entropy rate H(X) per step for the stationary Markov chain. A general closed form solution for the entropies H(T(ij)) is given by H = K - K + H(DELTA), where H is the matrix of trajectory entropies H(ij) = H(T(ij)); K (I - P + A)-1 (H* - H(DELTA)); K is a matrix in which the ijth element K(ij) equals the diagonal element K(jj) of K; A is the matrix of stationary probabilities with entries A(ij) = mu(j); H* is the matrix of single-step entropies with entries H(ij)* = H(P(i)) = -SIGMA(k) P(ik) log P(ik); and H(DELTA) is a diagonal matrix with entries (H(DELTA))ii = H(X)/mu(i). C1 STANFORD UNIV,DEPT ELECT ENGN,STANFORD,CA 94305. STANFORD UNIV,DEPT STAT,STANFORD,CA 94305. RP EKROOT, L (reprint author), JET PROP LAB,COMMUN SYST RES GRP,238-420,4800 OAK GROVE,PASADENA,CA 91109, USA. NR 5 TC 16 Z9 16 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9448 J9 IEEE T INFORM THEORY JI IEEE Trans. Inf. Theory PD JUL PY 1993 VL 39 IS 4 BP 1418 EP 1421 DI 10.1109/18.243461 PG 4 WC Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MG075 UT WOS:A1993MG07500031 ER PT J AU PROTZEL, PW PALUMBO, DL ARRAS, MK AF PROTZEL, PW PALUMBO, DL ARRAS, MK TI PERFORMANCE AND FAULT-TOLERANCE OF NEURAL NETWORKS FOR OPTIMIZATION SO IEEE TRANSACTIONS ON NEURAL NETWORKS LA English DT Article ID LINEAR-PROGRAMMING CIRCUIT; TRAVELING-SALESMAN PROBLEM; COMPUTATION; STABILITY; ALGORITHM; HOPFIELD; TANK AB One of the key benefits of future hardware implementations of certain artificial neural networks (ANN's) is their apparently ''built-in'' fault-tolerance, which makes them potential candidates for critical tasks with high reliability requirements. This paper investigates the fault-tolerance characteristics of time-continuous, recurrent ANN's that can be used to solve optimization problems. The performance of these networks is first illustrated by using well-known model problems like the Traveling Salesman Problem and the Assignment Problem. The ANN's are then subjected to up to 13 simultaneous ''stuck-at-1'' or ''stuck-at-0'' faults for network sizes of up to 900 ''neurons.'' The effect of these faults on the performance is demonstrated and the cause for the observed fault-tolerance is discussed. An application is presented in which a network performs a critical task for a real-time distributed processing system by generating new task allocations during the reconfiguration of the system. The performance degradation of the ANN under the presence of faults is investigated by large-scale simulations and the potential benefits of delegating a critical task to a fault-tolerant network are discussed. C1 NASA,LANGLEY RES CTR,SYST VALIDAT METHODS BRANCH,HAMPTON,VA 23665. RP PROTZEL, PW (reprint author), BAVARIAN RES CTR KNOWLEDGE BASED SYST,NEURAL NETWORKS & FUZZY LOG GRP,W-8520 ERLANGEN,GERMANY. NR 29 TC 27 Z9 27 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1045-9227 J9 IEEE T NEURAL NETWOR JI IEEE Trans. Neural Netw. PD JUL PY 1993 VL 4 IS 4 BP 600 EP 614 DI 10.1109/72.238315 PG 15 WC Computer Science, Artificial Intelligence; Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA LZ807 UT WOS:A1993LZ80700006 PM 18267761 ER PT J AU YAMAGATA, Y OSHI, T KATSUKAWA, H KATO, S SAKURAI, Y KIRKHAM, H JOHNSTON, AR AF YAMAGATA, Y OSHI, T KATSUKAWA, H KATO, S SAKURAI, Y KIRKHAM, H JOHNSTON, AR TI DEVELOPMENT OF OPTICAL CURRENT TRANSFORMERS AND APPLICATION TO FAULT LOCATION SYSTEMS FOR SUBSTATIONS SO IEEE TRANSACTIONS ON POWER DELIVERY LA English DT Article; Proceedings Paper CT 1992 SUMMER MEETING OF IEEE / POWER-ENGINEERING-SOC CY JUL 12-16, 1992 CL SEATTLE, WA SP IEEE, POWER ENGN SOC DE OPTICAL CT; OPTICAL INSULATOR; FAULT LOCATION SYSTEM; FARADAY EFFECT; BSO; OPTICAL FIBER AB Since optical instrumentation technology provides excellent electromagnetic noise rejection and high insulation performance, it can be effectively applied to many applications for maintenance and supervision of electric power systems. The optical current transformer developed is based on the principle of Faraday Effect. Also, the information measured by the optical CT is transmitted to the ground side through optical fibers contained in an insulator. As an application of the optical CT, a new fault location system has been developed. C1 NGK INSULATORS LTD,DEPT RES & TECH DEV,NAGOYA,JAPAN. JET PROP LAB,PASADENA,CA 91109. RP YAMAGATA, Y (reprint author), TOKYO ELECT POWER CO LTD,DIV SUBSTN FACILITIES,TOKYO,JAPAN. NR 5 TC 15 Z9 18 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0885-8977 J9 IEEE T POWER DELIVER JI IEEE Trans. Power Deliv. PD JUL PY 1993 VL 8 IS 3 BP 866 EP 873 DI 10.1109/61.252692 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA LY720 UT WOS:A1993LY72000014 ER PT J AU HILL, LL AF HILL, LL TI AUTOMATED SUPPORT TO INDEXING - HODGE,GM SO INFORMATION PROCESSING & MANAGEMENT LA English DT Book Review RP HILL, LL (reprint author), NASA,STI PROGRAM,INFORMAT INT ASSOCIATES,WASHINGTON,DC 20546, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0306-4573 J9 INFORM PROCESS MANAG JI Inf. Process. Manage. PD JUL-AUG PY 1993 VL 29 IS 4 BP 528 EP 531 DI 10.1016/0306-4573(93)90052-F PG 4 WC Computer Science, Information Systems; Information Science & Library Science SC Computer Science; Information Science & Library Science GA LN321 UT WOS:A1993LN32100016 ER PT J AU SPEZIALE, CG ABID, R AF SPEZIALE, CG ABID, R TI REYNOLDS STRESS CALCULATIONS OF HOMOGENEOUS TURBULENT SHEAR-FLOW WITH BOUNDED ENERGY-STATES SO INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS LA English DT Article ID ISOTROPIC TURBULENCE; DECAY AB Reynolds stress calculations of homogeneous turbulent shear flow are conducted with a second-order closure model modified to account for non-equilibrium vortex stretching in the dissipation rate transport equation as recently proposed by Bernard and Speziale [J. Fluids Engng 114, 29 (1992)]. As with the earlier reported K-epsilon model calculations incorporating this vortex stretching effect, a production-equals-dissipation equilibrium is obtained with bounded turbulent kinetic energy and dissipation. However, this equilibrium is now not achieved until the dimensionless time St > 60 - an elapsed time that is at least twice as large as any of those considered in previous numerical and physical experiments on homogeneous shear flow. Direct quantitative comparisons between the model predictions and the results of experiments are quite favorable. In particular, it is shown that the inclusion of this non-equilibrium vortex stretching effect has the capability of explaining the significant range of production to dissipation ratios observed in experiments. C1 NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,HIGH TECHNOL CORP,HAMPTON,VA 23665. NR 12 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0020-7462 J9 INT J NONLINEAR MECH JI Int. J. Non-Linear Mech. PD JUL PY 1993 VL 28 IS 4 BP 373 EP 378 DI 10.1016/0020-7462(93)90012-A PG 6 WC Mechanics SC Mechanics GA LT888 UT WOS:A1993LT88800002 ER PT J AU SMITH, SC KROO, IM AF SMITH, SC KROO, IM TI COMPUTATION OF INDUCED DRAG FOR ELLIPTIC AND CRESCENT-SHAPED WINGS SO JOURNAL OF AIRCRAFT LA English DT Article AB Recent interest in the induced drag characteristics of crescent-shaped wings has led to a closer look at the methods used for determination of induced drag from computational aerodynamic methods. Induced drag may be computed by integration of surface pressure or by evaluation of a contour integral in the Trefftz plane. A high-order panel method was used to study the induced drag of elliptical and crescent-shaped wings using both techniques. Induced drag computations using surface pressure integration were strongly affected by panel density and angle of attack. Drag computations for the crescent wing were especially sensitive to spanwise panel density because of the complex flowfield near the tip. Trefftz-plane results for the two wing planforms were not sensitive to panel density or angle of attack. The effect of correctly modeling the force-free, rolled-up wake geometry on the predicted span efficiency was demonstrated for both wing planforms. The span efficiency predicted from Trefftz-plane integration was about 0.97 for the elliptical wing and 0.99 for the crescent wing, both somewhat less than the classical theoretical maximum for planar wings. Most of the apparent drag reduction of the crescent wing claimed in previous studies was probably an artifact of the surface-pressure integration. The slightly higher span efficiency for the crescent wing was attributed to a more nearly elliptical spanwise lift distribution. RP SMITH, SC (reprint author), NASA,AMES RES CTR,ADV AERODYNAM CONCEPTS BRANCH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 10 Z9 10 U1 2 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1993 VL 30 IS 4 BP 446 EP 452 DI 10.2514/3.46365 PG 7 WC Engineering, Aerospace SC Engineering GA LT798 UT WOS:A1993LT79800003 ER PT J AU HEEG, J GILBERT, MG POTOTZKY, AS AF HEEG, J GILBERT, MG POTOTZKY, AS TI ACTIVE CONTROL OF AEROTHERMOELASTIC EFFECTS FOR A CONCEPTUAL HYPERSONIC AIRCRAFT SO JOURNAL OF AIRCRAFT LA English DT Article AB This article describes the procedures and results of aeroservothermoelastic studies. The objectives of these studies are to develop the necessary procedures for performing an aeroelastic analysis of an aerodynamically heated vehicle and to analyze a configuration in the classical ''cold'' state and in a ''hot'' state. Major tasks include the development of the structural and aerodynamic models, open loop analyses, design of active control laws for improving dynamic responses, and analyses of the closed loop vehicles. The analyses performed focused on flutter speed calculations, short period eigenvalue trends, and statistical analyses of the vehicle response to controls and turbulence. Improving the ride quality of the vehicle, and raising the flutter boundary of the aerodynamically heated vehicle up to that of the cold vehicle, were the objectives of the control law design investigations. RP HEEG, J (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,AEROSERVOELAST BRANCH,M-S243,HAMPTON,VA 23665, USA. NR 0 TC 23 Z9 27 U1 0 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1993 VL 30 IS 4 BP 453 EP 458 DI 10.2514/3.56890 PG 6 WC Engineering, Aerospace SC Engineering GA LT798 UT WOS:A1993LT79800004 ER PT J AU THOMAS, JL AF THOMAS, JL TI REYNOLDS-NUMBER EFFECTS ON SUPERSONIC ASYMMETRICAL FLOWS OVER A CONE SO JOURNAL OF AIRCRAFT LA English DT Article AB The supersonic viscous flow over a 5-deg half-angle cone at an angle of attack of four times the cone half-angle is studied computationally using both the conical and the three-dimensional Navier-Stokes equations. The numerical solutions were obtained with an implicit, upwind-biased algorithm. Asymmetrical flowfields of the absolute-instability type are found using the conical-flow equations which agree with published results. However, the absolute instabilities of the originally symmetric flow found with the conical equations do not occur in the three-dimensional simulations, although spurious asymmetric three-dimensional flows for symmetric bodies arise if the grid resolution is insufficient in the nose region. The asymmetric flows computed with the three-dimensional equations are convective instabilities and are possible if the local Reynolds number exceeds a critical value and a fixed geometric asymmetry is imposed. A continuous range of asymmetries can be developed, depending on the size of the disturbance and the Reynolds number. As the Reynolds number is increased, the asymmetries demonstrate a bistable behavior at levels of side force consistent with those predicted using the conical equations. Below a certain critical Reynolds number, any now asymmetries arising from a geometrical asymmetry are damped with increasing distance downstream from the geometrical asymmetry. RP THOMAS, JL (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,AERODYNAM BRANCH,MS 128,HAMPTON,VA 23665, USA. NR 0 TC 16 Z9 16 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1993 VL 30 IS 4 BP 488 EP 495 DI 10.2514/3.46370 PG 8 WC Engineering, Aerospace SC Engineering GA LT798 UT WOS:A1993LT79800008 ER PT J AU MEHTA, UB AF MEHTA, UB TI AEROSPACE PLANE DESIGN CHALLENGE - CREDIBLE COMPUTATIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB Computational fluid dynamics (CFD) is necessary in the design processes of all current aerospace plane programs. Single-stage-to-orbit (SSTO) aerospace planes with air-breathing supersonic and hypersonic combustion are going to be largely designed by means of CFD. The principal challenge of the aerospace plane design is to provide credible CFD results to work from, to assess the risk associated with the use of those results, and to certify CFD codes that produce credible results. CFD uncertainties, credibility requirement, a guide for establishing credibility, and responsibility for credibility are discussed in order to establish the credibility of CFD results used in design. Quantification of CFD uncertainties helps to assess success risks and safety risks, and the development of CFD as a design tool requires code certification. This credibility challenge is managed by ''designing'' the designers to use CFD effectively, by teaming the computational fluid dynamicists with the designers, by ensuring continuous enhancement of credibility, and by balancing the design process to achieve a judicious balance of computations and measurements. RP MEHTA, UB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 4 Z9 4 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1993 VL 30 IS 4 BP 519 EP 525 DI 10.2514/3.46374 PG 7 WC Engineering, Aerospace SC Engineering GA LT798 UT WOS:A1993LT79800012 ER PT J AU AMBUR, DR REHFIELD, LW AF AMBUR, DR REHFIELD, LW TI EFFECT OF STIFFNESS CHARACTERISTICS ON THE RESPONSE OF COMPOSITE GRID-STIFFENED STRUCTURES SO JOURNAL OF AIRCRAFT LA English DT Article AB A study of the effect of stiffness discontinuities and structural parameters on the response of continuous-filament grid-stiffened flat panels is presented. The buckling load degradation due to manufacturing-introduced stiffener discontinuities associated with a filament cut-and-add approach at the stiffener intersections is investigated. For practical discontinuity sizes, the reduction in buckling load is negligible. The degradation of buckling resistance in isogrid flat panels subjected to uniaxial compression, combined axial compression, shear loading conditions, and induced damage, is quantified using finite element analysis. The combined loading case is the most critical one. The benefit of utilizing nonsolid stiffener cross sections is evaluated. Nonsolid stiffener cross sections, such as a foam-filled blade or hat with a 0-deg dominant cap, result in grid-stiffened structures that are structurally very efficient for wing and fuselage applications. The results of a study of the ability of grid-stiffened structural concepts to enhance the effective Poisson's ratio of a panel is presented. Grid-stiffened concepts create a high effective Poisson's ratio which can produce large camber deformations for certain elastic tailoring applications. RP AMBUR, DR (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT MECH,AIRCRAFT STRUCT BRANCH,HAMPTON,VA 23665, USA. NR 0 TC 7 Z9 7 U1 2 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1993 VL 30 IS 4 BP 541 EP 546 DI 10.2514/3.46377 PG 6 WC Engineering, Aerospace SC Engineering GA LT798 UT WOS:A1993LT79800015 ER PT J AU GUILLORY, AR JEDLOVEC, GJ FUELBERG, HE AF GUILLORY, AR JEDLOVEC, GJ FUELBERG, HE TI A TECHNIQUE FOR DERIVING COLUMN-INTEGRATED WATER-CONTENT USING VAS SPLIT-WINDOW DATA SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID CHANNEL MICROWAVE RADIOMETER; PRECIPITABLE WATER; OPTIMIZED RETRIEVALS; VAPOR; SURFACE; ALGORITHM; SATELLITE; IMAGERY; FIELDS; LIQUID AB An algorithm is examined that uses Visible-Infrared Spin Scan Radiometer (VISSR) Atmospheric Sounder (VAS) 11- and 12-mum (split-window) data to derive column-integrated water content (IWC) at mesoscale resolution. The algorithm is physically based and derives its first-guess information from radiosonde data. The procedure is applied first to a test case dataset and then to the 19 June 1986 study day from the Cooperative Huntsville Meteorological Experiment (COHMEX). Ground truth data for verifying results from the technique include IWC from National Weather Service and COHMEX radiosondes, the Multispectral Atmospheric Mapping Sensor (MAMS), and a special set of VAS soundings (12 channel) using an independent retrieval method. Results from the test case show reasonable accuracy with the root-mean-square errors as low as +/-3.8 mm. On the 19 June case study day IWC analyses depict reasonable gradients and exhibit good spatial and temporal continuity. Furthermore, they provide insight into preferred regions for cumulus cloud and thunderstorm formation. On the average, a mean absolute retrieval error of 2.4 mm (an 8.1% error) and a root-mean-square error of +/-2.9 mm are obtained on the case study day. These results compare favorably with those from existing VAS IWC techniques. Overall, the findings indicate that the technique has excellent potential to depict mesoscale moisture variations. C1 FLORIDA STATE UNIV,DEPT METEOROL,TALLAHASSEE,FL 32306. RP GUILLORY, AR (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,EARTH SYST OBSERVING BRANCH ES43,HUNTSVILLE,AL 35812, USA. NR 44 TC 16 Z9 16 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD JUL PY 1993 VL 32 IS 7 BP 1226 EP 1241 DI 10.1175/1520-0450(1993)032<1226:ATFDCI>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LK856 UT WOS:A1993LK85600005 ER PT J AU SIEG, RM ALTEROVITZ, SA CROKE, ET HARRELL, MJ TANNER, M WANG, KL MENA, RA YOUNG, PG AF SIEG, RM ALTEROVITZ, SA CROKE, ET HARRELL, MJ TANNER, M WANG, KL MENA, RA YOUNG, PG TI CHARACTERIZATION OF SIXGE1-X/SI HETEROSTRUCTURES FOR DEVICE APPLICATIONS USING SPECTROSCOPIC ELLIPSOMETRY SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID DIELECTRIC FUNCTION; ENHANCEMENT-MODE; VARIABLE ANGLE; THICKNESS AB Spectroscopic ellipsometry (SE) characterization of several complex SiGe1-x/Si heterostructures prepared for device fabrication, including structures for heterojunction bipolar transistors (HBT), p- and n-type heterostructure modulation-doped field-effect transistors, has been performed. It is shown that SE can simultaneously determine all active layer thicknesses, SixGe1-x compositions, and the oxide overlayer thickness, with only a general knowledge of the structure topology needed a priori. The characterization of HBT material includes the SE analysis of a SixGe1-x layer deeply buried (600 nm) under the silicon emitter and cap layers. In the SE analysis of n-type heterostructures, a silicon layer under tensile strain was examined. It was found that an excellent fit can be obtained using optical constants of unstrained silicon to represent the strained silicon conduction layer. SE was also used to measure lateral sample homogeneity, providing quantitative identification of the inhomogeneous layer. Surface overlayers resulting from prior sample processing were also detected and measured quantitatively. These results should allow SE to be used extensively as a nondestructive means of characterizing SixGe1-x/Si heterostructures prior to device fabrication and testing. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. HUGHES RES LABS,MALIBU,CA 90265. UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024. UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606. RP SIEG, RM (reprint author), CLEVELAND STATE UNIV,CLEVELAND,OH 44115, USA. NR 30 TC 8 Z9 8 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 1 PY 1993 VL 74 IS 1 BP 586 EP 595 DI 10.1063/1.355271 PG 10 WC Physics, Applied SC Physics GA LK469 UT WOS:A1993LK46900088 ER PT J AU SUD, YC CHAO, WC WALKER, GK AF SUD, YC CHAO, WC WALKER, GK TI DEPENDENCE OF RAINFALL ON VEGETATION - THEORETICAL CONSIDERATIONS, SIMULATION EXPERIMENTS, OBSERVATIONS, AND INFERENCES FROM SIMULATED ATMOSPHERIC SOUNDINGS SO JOURNAL OF ARID ENVIRONMENTS LA English DT Article; Proceedings Paper CT INTERNATIONAL SYMP ON EVOLUTION OF DESERTS CY FEB 11-19, 1992 CL PHYS RES LAB, AHMEDABAD, INDIA HO PHYS RES LAB ID SEMI-ARID REGIONS; GENERAL-CIRCULATION MODEL; LAND-SURFACE PROCESSES; JULY CIRCULATION; TROPICAL DEFORESTATION; BIOSPHERE MODEL; GCM SIMULATION; CLIMATE CHANGE; ALBEDO; PRECIPITATION RP SUD, YC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GSFC,ATMOSPHERES LAB,CLIMATE & RADIAT BRANCH,GREENBELT,MD 20771, USA. NR 58 TC 43 Z9 44 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0140-1963 J9 J ARID ENVIRON JI J. Arid. Environ. PD JUL PY 1993 VL 25 IS 1 BP 5 EP 18 DI 10.1006/jare.1993.1038 PG 14 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA LZ366 UT WOS:A1993LZ36600002 ER PT J AU LANGEL, RA PURUCKER, M RAJARAM, M AF LANGEL, RA PURUCKER, M RAJARAM, M TI THE EQUATORIAL ELECTROJET AND ASSOCIATED CURRENTS AS SEEN IN MAGSAT DATA SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article ID DIURNAL TIDAL WINDS; 3-DIMENSIONAL STRUCTURE; IONOSPHERIC CURRENTS; CURRENT SYSTEM; FIELD; DYNAMO; MODEL AB Magsat data are re-examined with regard to the presence and character of fields due to the equatorial electrojet and meridional currents at dawn and dusk local times. Dip-latitude organized field variations at dawn are: (1) extremely weak, (2) extremely variable with longitude, (3) inconsistent with the pattern expected from a line or narrow sheet current. It is shown that the use of Magsat dusk data can 'contaminate' a main field model, introducing apparent equatorial electrojet effects into the dawn data. Fields due to the equatorial electrojet and (presumably) associated meridional currents are clearly present in the dusk data. They show a variation with longitude which is apparently associated with the longitudinal variation of the strength, or square of the strength, of the main field in the E-region. Also evident is a variation with time of the year, although data are available for only a six month period. The meridional currents are generally minimum during January and February and maximum either during November and December or March and April, depending upon longitude. The E-region horizontal currents are n-minimum in November and December and maximum in March and April, except for - 30-degrees to - 90-degrees longitude when the maximum occurs in January and February. Assuming that field gradients in local time are considerably smaller than field gradients in dip-latitude, current densities are estimated to be 1-3.6 muA/m2 for the horizontal current at 110 km and about 10-20 x 10(-9) A/m2 for the vertical currents at 400 km altitude. These results confirm and extend earlier results of Takeda and Maeda. Most models of the electrojet system in the literature disagree severely with these measurements either because their scope is inadequate or because of the wind system they assume. Those models which best describe the data invoke an eastward wind and/or an eastward electric field at dusk local time. C1 HUGHES STX CORP,LANHAM,MD 20706. INDIAN INST GEOMAGNETISM,BOMBAY 400005,INDIA. RP LANGEL, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. NR 49 TC 36 Z9 37 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD JUL PY 1993 VL 55 IS 9 BP 1233 EP 1269 DI 10.1016/0021-9169(93)90050-9 PG 37 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LG045 UT WOS:A1993LG04500004 ER PT J AU MARTIN, JML TAYLOR, PR LEE, TJ AF MARTIN, JML TAYLOR, PR LEE, TJ TI ACCURATE ABINITIO QUARTIC FORCE-FIELDS FOR THE IONS HCO+ AND HOC+ SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; HYDROGEN; ATOMS; CONTRACTION; ENERGIES; SINGLES; CM-1; HCN AB The quartic force fields of HCO+ and HOC+ have been computed using augmented coupled cluster methods and basis sets of spdf and spdfg quality. Calculations on HCN, CO, and N2 have been performed to assist in calibrating the computed results. Going from an spdf to an spdfg basis shortens triple bonds by about 0.004 angstrom, and increases the corresponding harmonic frequency by 10-20 cm-1, leaving bond distances about 0.003 angstrom too long and triple bond stretching frequencies about 5 cm-1 too low. Accurate estimates for the bond distances, fundamental frequencies, and thermochemical quantities are given. HOC+ lies 37.8 +/- 0.5 kcal/mol (0 K) above HCO+; the classical barrier height for proton exchange is 76.7 +/- 1.0 kcal/mol. C1 NASA,AMES RES CTR,RTC-230-3,MOFFETT FIELD,CA 94035. LIMBURGS UNIV CENTRUM,DEPT SBM,B-3590 DIEPENBEEK,BELGIUM. UNIV ANTWERP UIA,DEPT CHEM,B-2610 WILRIJK,BELGIUM. RP MARTIN, JML (reprint author), SAN DIEGO SUPERCOMP CTR,POB 85608,SAN DIEGO,CA 92186, USA. RI Lee, Timothy/K-2838-2012; Martin, Jan/A-7457-2008 OI Martin, Jan/0000-0002-0005-5074 NR 61 TC 54 Z9 54 U1 2 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUL 1 PY 1993 VL 99 IS 1 BP 286 EP 292 DI 10.1063/1.465806 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LJ308 UT WOS:A1993LJ30800031 ER PT J AU BOWMAN, JM GAZDY, B BENTLEY, JA LEE, TJ DATEO, CE AF BOWMAN, JM GAZDY, B BENTLEY, JA LEE, TJ DATEO, CE TI ABINITIO CALCULATION OF A GLOBAL POTENTIAL, VIBRATIONAL ENERGIES, AND WAVE-FUNCTIONS FOR HCN/HNC, AND A SIMULATION OF THE (A)OVER-TILDE-(X)OVER-TILDE EMISSION-SPECTRUM SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID OVERTONE TRANSITIONS; TRIATOMIC-MOLECULES; HCN; STATES; REPRESENTATION; SURFACE; CM-1; FREQUENCIES; SYSTEM; FIELD AB We present a potential energy surface for the HCN/HNC system which is a fit to extensive, high quality ab initio, coupled-cluster calculations. The new surface is an improved version of one that was reported previously by us [J. A. Bentley, J. M. Bowman, B. Gazdy, T. J. Lee, and C. E. Dateo, Chem. Phys. Lett. 198, 563 (1992)]. Exact vibrational calculations of energies and wave functions of HCN, HNC, and delocalized states are done with the new potential using a new method, which combines a truncation/recoupling method in a finite basis representation procedure with a moveable basis to describe the significant bend-CH stretch correlation. All HCN and HNC states with energies below the energy of the first delocalized state are reported and characterized. All delocalized states up to 18 347 cm-1 above the HCN zero-point energy and higher energy localized HCN states are also reported and characterized. Vibrational transition energies are compared with all available experimental data on HCN and HNC, including high CH-overtone states up to 23 063 cm-1. We also report a simulation of the A-X stimulated emission pumping (SEP) spectrum, and compare the results to experiment. The simulation is performed within the Franck-Condon approximation, and makes use of 400 even-bend wave functions for the ground electronic state, and a realistic vibrational wave function for the first excited bend state in the excited A state. The potential for the A state is slightly modified, relative to one implied by a previously reported force field, to improve agreement with the experimental fundamentals for the A state. In addition, the A-state wave function is adjusted slightly to improve agreement with the SEP spectrum. We also report Franck-Condon factors for odd bending states of HCN, with one quantum of vibrational angular momentum, in order to compare with the recent assignment by Jonas, Yang, and Wodtke [J. Chem. Phys. 97, 2284 (1992)], based on axis-switching arguments of a number of previously unassigned states in the SEP spectrum. C1 EMORY UNIV, CHERRY L EMERSON CTR SCI COMPUTAT, ATLANTA, GA 30322 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. ELORET INST, PALO ALTO, CA 94303 USA. RP BOWMAN, JM (reprint author), EMORY UNIV, DEPT CHEM, ATLANTA, GA 30322 USA. RI Lee, Timothy/K-2838-2012 NR 55 TC 178 Z9 180 U1 1 U2 8 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUL 1 PY 1993 VL 99 IS 1 BP 308 EP 323 DI 10.1063/1.465809 PG 16 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LJ308 UT WOS:A1993LJ30800034 ER PT J AU KAUFMAN, YJ CHOU, MD AF KAUFMAN, YJ CHOU, MD TI MODEL SIMULATIONS OF THE COMPETING CLIMATIC EFFECTS OF SO2 AND CO2 SO JOURNAL OF CLIMATE LA English DT Article ID SOLAR-RADIATION MEASUREMENTS; EFFECTIVE PARTICLE RADIUS; GLOBAL CLOUD ALBEDO; ATMOSPHERIC SULFUR; FEEDBACK PROCESSES; OPTICAL-THICKNESS; AEROSOLS; POLLUTION; SENSITIVITY; PARAMETERIZATIONS AB Sulfur dioxide-derived cloud condensation nuclei are expected to enhance the planetary albedo, thereby cooling the planet. This effect might counteract the global warming expected from enhanced greenhouse gases. A detailed treatment of the relationship between fossil fuel burning and the SO2 effect on cloud albedo is implemented in a two-dimensional model for assessing the climate impact. Although there are large gaps in our knowledge of the atmospheric sources and sinks of sulfate aerosol, it is possible to reach some general conclusions. Using a conservative approach, results show that the cooling induced by the SO2 emission can presently counteract 50% of the CO2 greenhouse warming. Since 1980, a strong warming trend has been predicted by the model, 0.15-degrees-C, during the 1980-1990 period alone. The model predicts that by the year 2060 the SO2 cooling reduces climate warming by 0.5-degrees-C or 25% for the Intergovernmental Panel on Climate Change (IPCC) business as usual (BAU) scenario and 0.2-degrees-C or 20% for scenario D (for a slow pace of fossil fuel burning). The hypothesis is examined that the different responses between the Northern Hemisphere (NH) and the Southern Hemisphere (SH) can be used to validate the presence of the SO2-induced cooling. Despite the fact that most of the SO2-induced cooling takes place in the Northern Hemispheric continents, the model-predicted difference in the temperature response between the NH and the SH of -0.2-degrees-C in 1980 is expected to remain about the same at least until 2060. This result is a combined effect of the much faster response of the continents than the oceans and of the larger forcing due to CO2 than due to the SO2. The climatic response to a complete filtering of SO2 from the emission products in order to reduce acid rain is also examined. The result is a warming surge of 0.4-degrees-C in the first few years after the elimination of the SO2 emission. RP KAUFMAN, YJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 64 TC 18 Z9 19 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUL PY 1993 VL 6 IS 7 BP 1241 EP 1252 DI 10.1175/1520-0442(1993)006<1241:MSOTCC>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP859 UT WOS:A1993LP85900001 ER PT J AU KRATZ, DP CHOU, MD YAN, MMH AF KRATZ, DP CHOU, MD YAN, MMH TI INFRARED RADIATION PARAMETERIZATIONS FOR THE MINOR CO2 BANDS AND FOR SEVERAL CFC BANDS IN THE WINDOW REGION SO JOURNAL OF CLIMATE LA English DT Article ID ATMOSPHERIC TRACE GASES; WATER-VAPOR; TRANSMISSION FUNCTIONS; SURFACE TEMPERATURES; SOLAR-RADIATION; CLIMATE MODELS; EARLY EARTH; GREENHOUSE; ABSORPTION; CHLOROFLUOROCARBONS AB Fast and accurate parameterizations have been developed for the transmission functions of the CO2 9.4- and 10.4-mum bands, as well as the CFC-11, CFC-12, and CFC-22 bands located in the 8-12-mum region. The parameterizations are based on line-by-line calculations of transmission functions for the CO2 bands and on high spectral resolution laboratory measurements of the absorption coefficients for the CFC bands. Also developed are the parameterizations for the H2O transmission functions for the corresponding spectral bands. Compared to the high-resolution calculations, fluxes at the tropopause computed with the parameterizations are accurate to within 10% when overlapping of gas absorptions within a band is taken into account. For individual gas absorption, the accuracy is of order 0%-2%. The climatic effects of these trace gases have been studied using a zonally averaged multilayer energy balance model, which includes seasonal cycles and a simplified deep ocean. With the trace gas abundances taken to follow the Intergovernmental Panel on Climate Change Low Emissions ''B'' scenario, the transient response of the surface temperature is simulated for the period 1900-2060. The minor CO2 and CFC bands contribute about 20%-25% of the total warming at the surface, which is comparable to the contribution from the CH4 and N2O bands. Collectively, these minor absorption bands account for 40%-45% of the total surface temperature increases. Thus, the climate warming due to absorption in these bands is comparable to that in the 15-mum CO2 band. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. SCI SYST & APPLICAT INC,LANHAM,MD. RP KRATZ, DP (reprint author), LOCKHEED ENGN & SCI CO,144 RES DR,HAMPTON,VA 23666, USA. NR 41 TC 5 Z9 5 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUL PY 1993 VL 6 IS 7 BP 1269 EP 1281 DI 10.1175/1520-0442(1993)006<1269:IRPFTM>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP859 UT WOS:A1993LP85900003 ER PT J AU SPENCER, RW AF SPENCER, RW TI GLOBAL OCEANIC PRECIPITATION FROM THE MSU DURING 1979-91 AND COMPARISONS TO OTHER CLIMATOLOGIES SO JOURNAL OF CLIMATE LA English DT Article ID MULTICHANNEL MICROWAVE RADIOMETER; TROPICAL RAINFALL; SATELLITE; RATES; GHZ; 30-DEGREES-S AB Oceanic precipitation is estimated on a 2.5-degrees grid for the period 1979-1991 from Microwave Sounding Unit (MSU) channels 1, 2, and 3 data gathered by seven separate TIROS-N satellites. Precipitation is diagnosed when cloud water and rainwater-induced radiometric warming of the channel 1 brightness temperatures (T(b)) exceeds a cumulative frequency distribution threshold of 15% after correction for airmass temperature determined from the channel 2 and 3 measurements. After intercalibration between satellites, the 13-year gridpoint field of average T(b) warming is calibrated in precipitation units with data from five to ten years of globally distributed low-elevation island and coastal rain accumulation measurements from 132 gauges. The calibration involves a single scale factor, and has a dependence on air temperature that is estimated from an MSU climatology. Comparisons between the satellite and raingage measurements of the average annual cycle in monthly precipitation are presented for 75 raingage locations from different climatic regimes. At 2.5-degrees gridpoint resolution, peak annual rainfall (5600 mm) occurs in a quasistationary portion of the ITCZ over the eastern Pacific, while peak monthly rainfall (over 900 mm) occurs in the northeastern Bay of Bengal in June. Comparisons between the MSU oceanic rainfall climatology and those of Jaeger (raingage), Legates and Wilmott (mostly ship synoptic code observations), and the GOES precipitation index (GPI) of Janowiak and Arkin (satellite infrared) reveal several important differences. Jaeger largely misses the extratropical storm tracks, as well as the intensity of the intertropical convergence zone in the eastern Pacific and western Atlantic. Legates and Wilmott have the features that Jaeger missed, but without the intensity that the MSU suggests. Two prominent differences in the Pacific ITCZ depiction are probably due to a lack of ship data in the Legates and Wilmott climatology. The GPI shows more rainfall over the eastern Indian Ocean than the MSU, and much less than the MSU over the tropical eastern Pacific, tropical western Atlantic, and in the western Pacific extratropical storm track. These differences are related to regional differences in the amount of cirrus cloud activity versus cloud water activity. The largest consistent discrepancy between the MSU and other climatologies is the eastern Pacific ITCZ, where the MSU indicates up to 8 mm day-1 more rainfall than the GPI. Raingage data from the Line Islands, which protrude into one end of this maximum, suggests that the large MSU amounts could be real. Microwave sounding unit and GPI depictions of seasonal rainfall variability associated with the ENSO warm event of 1991-92 show good agreement in the large-scale patterns. Comparisons of MSU pentad rain estimates for a small region near Sumatra to the GOES precipitation index (GPI) and two numerical weather prediction model forecasts show much better agreement between the two satellite estimates than between either satellite estimate and the model forecasts. Remaining disagreements between the two satellite methods are in the form of numerous GPI-diagnosed light-to-moderate rain amounts for which the MSU shows little or no precipitation. This is consistent with the expectation that cold cirrus cloudiness, on which the GPI estimates are based, often covers larger areas with more persistence than does the rainfall on short time scales. Monthly gridpoint anomaly sampling skill is estimated during 81 months of two-satellite coverage by comparisons between the anomalies measured by the satellites separately. At the 2.5-degrees gridpoint scale, anomaly correlations are generally above 0.8 in the tropics, reaching a peak of 0.99 in the center of the tropical Pacific Ocean. Extratropical gridpoint anomaly correlations are lower, due to smaller interannual variability, ranging from 0.2 to 0.8. The corresponding single-satellite gridpoint anomaly sampling error ranges from 10 mm month-1 to 40 mm month-1, the lower errors occurring in climatologically light rainfall areas, and greater errors in the heavy rainfall areas. An example of monthly anomalies in oceanic rainfall is presented for February 1983. RP SPENCER, RW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,DIV EARTH SCI & APPLICAT,ES43-71-92,HUNTSVILLE,AL 35812, USA. NR 50 TC 281 Z9 286 U1 1 U2 13 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUL PY 1993 VL 6 IS 7 BP 1301 EP 1326 DI 10.1175/1520-0442(1993)006<1301:GOPFTM>2.0.CO;2 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LP859 UT WOS:A1993LP85900005 ER PT J AU LIOU, MS STEFFEN, CJ AF LIOU, MS STEFFEN, CJ TI A NEW FLUX SPLITTING SCHEME SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID REAL GASES RP LIOU, MS (reprint author), NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135, USA. NR 19 TC 496 Z9 554 U1 5 U2 21 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUL PY 1993 VL 107 IS 1 BP 23 EP 39 DI 10.1006/jcph.1993.1122 PG 17 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA LK455 UT WOS:A1993LK45500003 ER PT J AU HUBERT, JA FRIPP, AL WELCH, CS AF HUBERT, JA FRIPP, AL WELCH, CS TI RESOLUTION OF THE DISCREPANCY BETWEEN TEMPERATURE INDICATED INTERFACE AND RADIOGRAPHICALLY DETERMINED INTERFACE IN A VERTICAL BRIDGMAN FURNACE SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID GROWTH AB The melt-solid interface position was measured during the Bridgman growth of germanium both by X-ray imaging and by temperature measurements. X-ray imaging displayed an interface location through a change in image intensity representing the difference in density between liquid and solid germanium. The temperature measurements were obtained with thermocouples inserted into a centerline capillary tube in the germanium sample and translated to varying positions. The temperature profile indicated an interface location at the change in slope of temperature representing the difference in thermal conductivity between liquid and solid germanium. Comparisons between these measurement techniques showed a 3 mm difference in position of the interface. The position measured via radiography was lower (i.e. colder) than that measured by the temperature profile. The measured temperature was expected to be lower due to conduction of heat along the thermocouples but a spatial shift of the gradient discontinuity was not anticipated. The temperature field of the ampoule, growth material and measurement thermocouples was analyzed via numerical analysis. It was found that both the lower temperature and the spatial shift of the discontinuity in temperature gradient were a result of an end effect in the thermocouples. This end effect is caused by the low heat flux to the thermocouples which causes the temperature gradient at the tip of the thermocouples to be significantly lower than the temperature gradient of the environment. With this insight, a simple extension was made to the heat equation for a thin cylindrical rod in a temperature gradient. This analytical solution provided a good fit to both the numerical solution and the radiography data. This work provides a new insight into temperature measurement in a high gradient region. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 17 TC 8 Z9 8 U1 0 U2 0 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 JUL PY 1993 VL 131 IS 1-2 BP 75 EP 82 DI 10.1016/0022-0248(93)90398-G PG 8 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA LM774 UT WOS:A1993LM77400010 ER PT J AU CHEN, SK LEFEBVRE, AH ROLLBUHLER, J AF CHEN, SK LEFEBVRE, AH ROLLBUHLER, J TI FACTORS INFLUENCING THE CIRCUMFERENTIAL LIQUID DISTRIBUTION FROM PRESSURE-SWIRL ATOMIZERS SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article AB Measurements of circumferential liquid distribution are carried out over ranges of injection pressure from 0.34 to 1.72 MPa (50 to 250 psi) using five different simplex nozzles to achieve variations in the discharge orifice length/diameter ratio from 0.5 to 4.0. Two additional simplex nozzles of the same flow number are also examined in order to ascertain the effect of variations in the number of swirl chamber feed slots on circumferential liquid distribution. Mixtures of water and glycerine are used to provide a twelve to one variation in liquid viscosity. The results obtained show that spray uniformity improves markedly at higher injection pressures. Increase in liquid viscosity also has a beneficial effect on spray uniformity. The most uniform circumferential liquid distributions are obtained with nozzles having a discharge orifice length/diameter ratio of between 11/2 and 2. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHEN, SK (reprint author), PURDUE UNIV,CTR THERMAL SCI & PROP,W LAFAYETTE,IN 47907, USA. NR 8 TC 15 Z9 18 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD JUL PY 1993 VL 115 IS 3 BP 447 EP 452 DI 10.1115/1.2906729 PG 6 WC Engineering, Mechanical SC Engineering GA LP656 UT WOS:A1993LP65600003 ER PT J AU MICKLOW, GJ ROYCHOUDHURY, S NGUYEN, HL CLINE, MC AF MICKLOW, GJ ROYCHOUDHURY, S NGUYEN, HL CLINE, MC TI EMISSIONS REDUCTION BY VARYING THE SWIRLER AIR-FLOW SPLIT IN ADVANCED GAS-TURBINE COMBUSTORS SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 37TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 01-04, 1992 CL COLOGNE, GERMANY AB A staged combustor concept for reducing pollutant emissions is currently under investigation. A numerical study was performed to investigate the chemically reactive flow with liquid spray injection for staged combustion. The staged combustor consists of an airblast atomizer fuel injector, a rich burn section, a converging connecting pipe, a quick mix zone, a diverging connecting pipe and a lean combustion zone. For computational efficiency, the combustor was split into two subsystems, i.e., the fuel nozzle/rich burn section and the quick mix/lean burn section. The current study investigates the effect of varying the mass flow rate split between the swirler passages for an equivalence ratio of 2.0 on fuel distribution, temperature distribution, and emissions for the fuel nozzle/rich burn section of a staged combustor. It is seen that optimizing these parameters can substantially improve combustor performance and reduce combustor emissions. The optimal mass flow rate split for reducing NO(x), emissions based on the numerical study was the same as found by experiment. C1 LOS ALAMOS NATL LAB,LOS ALAMOS,CA. NASA,LEWIS RES CTR,CLEVELAND,OH 44155. RP MICKLOW, GJ (reprint author), UNIV FLORIDA,DEPT MECH ENGN,COMPUTAT FLUID DYNAM LAB,GAINESVILLE,FL 32601, USA. NR 23 TC 9 Z9 9 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD JUL PY 1993 VL 115 IS 3 BP 563 EP 569 DI 10.1115/1.2906744 PG 7 WC Engineering, Mechanical SC Engineering GA LP656 UT WOS:A1993LP65600018 ER PT J AU CHU, YC ROKHLIN, SI BAAKLINI, GY AF CHU, YC ROKHLIN, SI BAAKLINI, GY TI ULTRASONIC ASSESSMENT OF INTERFACIAL OXIDATION DAMAGE IN CERAMIC-MATRIX COMPOSITES SO JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT INTERNATIONAL SYMP ON MICROMECHANICS OF CERAMICS AND CERAMIC COMPOSITES / 1992 ANNUAL MEETING OF THE AMERICAN SOC OF MECHANICAL ENGINEERS CY NOV 08-13, 1992 CL ANAHEIM, CA SP AMER SOC MECH ENGINEERS AB A new approach to characterizing oxidation damage in ceramic matrix composites using ultrasonic techniques is proposed. In this approach the elastic constants of the composite are determined nondestructively by measuring the angular dependence of both longitudinal and transverse wave velocities. A micromechanical model for composites with anisotropic constituents is used to find the anisotropic properties of an effective fiber which is a combination of the fiber and the interface. Interfacial properties are extracted from the properties of this effective fiber by analyzing the difference between effective and actual fiber properties. Unidirectional [0]28 SiC/Si3N4 composites with 30 percent fiber volume fraction and 30 percent matrix porosity are used. The samples are exposed in a flowing oxygen environment at elevated temperatures, up to 1400-degrees-C, for 100 hours and then measured by ultrasonic methods at room temperature. The Young's modulus in the fiber direction of the sample oxidized at 600-degrees-C decreased significantly but it was unchanged for samples oxidized at temperatures above 1200-degrees-C. The transverse moduli obtained from ultrasonic measurements decrease continuously up to 1200-degrees-C. The shear stiffnesses show behavior similar to the transverse moduli. The effective elastic moduli of the interfacial carbon coating are determined from the experimental data and their change due to thermal oxidation is discussed. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHU, YC (reprint author), OHIO STATE UNIV,DEPT WELDING ENGN,COLUMBUS,OH 43210, USA. NR 14 TC 12 Z9 12 U1 2 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-4289 J9 J ENG MATER-T ASME JI J. Eng. Mater. Technol.-Trans. ASME PD JUL PY 1993 VL 115 IS 3 BP 237 EP 243 DI 10.1115/1.2904213 PG 7 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA LN819 UT WOS:A1993LN81900003 ER PT J AU STABENAU, EK HEMING, TA AF STABENAU, EK HEMING, TA TI DETERMINATION OF THE CONSTANTS OF THE HENDERSON-HASSELBALCH EQUATION, ALPHA-CO2 AND PKA, IN SEA-TURTLE PLASMA SO JOURNAL OF EXPERIMENTAL BIOLOGY LA English DT Note DE TURTLE; LEPIDOCHELYS-KEMPI; PLASMA; ALPHA-CO2; PKA ID BLOOD C1 UNIV TEXAS,MED BRANCH,DEPT INTERNAL MED,GALVESTON,TX 77550. NOAA,NATL MARINE FISHERIES SERV,GALVESTON,TX 77550. RP STABENAU, EK (reprint author), UNIV TEXAS,MED BRANCH,DEPT PHYSIOL & BIOPHYS,GALVESTON,TX 77550, USA. NR 7 TC 18 Z9 18 U1 1 U2 2 PU COMPANY OF BIOLOGISTS LTD PI CAMBRIDGE PA BIDDER BUILDING CAMBRIDGE COMMERCIAL PARK COWLEY RD, CAMBRIDGE, CAMBS, ENGLAND CB4 4DL SN 0022-0949 J9 J EXP BIOL JI J. Exp. Biol. PD JUL PY 1993 VL 180 BP 311 EP 314 PG 4 WC Biology SC Life Sciences & Biomedicine - Other Topics GA LN966 UT WOS:A1993LN96600021 ER PT J AU ACUNA, MH CONNERNEY, JEP NESS, NF AF ACUNA, MH CONNERNEY, JEP NESS, NF TI NEPTUNE MAGNETIC-FIELD - CALCULATION OF FIELD GEOMETRIC INVARIANTS DERIVED FROM THE I8E1 GSFC/BRI MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ENERGETIC PARTICLES; MAGNETOSPHERE; URANUS AB A simplified description of the Neptunian magnetic field derived from the Goddard Space Flight Center/Bartol Research Institute 18E1 model which includes internal terms up to and including the octupole (but no external terms) has been used to compute numerically L shell values along the Voyager 2 encounter trajectory and those associated with the N1 through N6 moons and N1R through N6R rings. The complex magnetic field geometry and the rapid rotation of the planet combine to produce an expectation of numerous times when absorption signatures should be observed as a result of the interaction between the trapped particle population and the Neptunian moons and rings. Thus a complete understanding of the observed charged particle fluxes and their variation along the Voyager 2 trajectory must take into account these geometrically anticipated interactions. Similar to Uranus, the large tilt between the dipole term and the rotation axis causes the moons and rings to sweep a very large range of L shells. Furthermore, their orbital motion introduces additional periodicities, causing the maxima and minima in L space to vary systematically with time. The unambiguous association of predicted and observed absorption signatures and times with a particular ring or moon is made very difficult by the superposition of many individual effects. The extremely rapid excursion in L space by Voyager 2 near closest approach, a region most significant for magnetic field models, apparently does not facilitate the unique associations previously used at other planets to provide an independent assessment of the global accuracy of the mathematical models of the field which are inherently nonunique. C1 UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. RP ACUNA, MH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERRESTRIAL PHYS LAB,CODE 695,GREENBELT,MD 20771, USA. RI connerney, john/I-5127-2013; OI connerney, jack/0000-0001-7478-6462 NR 26 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1993 VL 98 IS A7 BP 11275 EP 11284 DI 10.1029/92JA02981 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LL822 UT WOS:A1993LL82200013 ER PT J AU KIVELSON, MG KENNEL, CF MCPHERRON, RL RUSSELL, CT SOUTHWOOD, DJ WALKER, RJ KHURANA, KK COLEMAN, PJ HAMMOND, CM ANGELOPOULOS, V LAZARUS, AJ LEPPING, RP HUGHES, TJ AF KIVELSON, MG KENNEL, CF MCPHERRON, RL RUSSELL, CT SOUTHWOOD, DJ WALKER, RJ KHURANA, KK COLEMAN, PJ HAMMOND, CM ANGELOPOULOS, V LAZARUS, AJ LEPPING, RP HUGHES, TJ TI THE GALILEO EARTH ENCOUNTER - MAGNETOMETER AND ALLIED MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FLUX ROPES; GEOMAGNETIC NEUTRAL SHEET; PLASMA SHEET; TAIL; IMF; MAGNETOTAIL; COMPONENT; POSITION; SHAPE AB The Galileo spacecraft flew by Earth on December 8, 1990, at high speed along a trajectory that traversed the magnetotail and the near Earth magnetosphere. Galileo's orbit through a region of the magnetotail from which limited data are available provided a unique opportunity to study a number of substorm-related phenomena. Several groups cooperated in collecting correlative data in order to take advantage of this special opportunity. Fortunately, geomagnetic conditions were rather disturbed during the entire day, and an interplanetary shock passed Earth when the spacecraft was in the magnetotail at about 30 R(E) geocentric distance. In this first report we provide an overview of the Galileo magnetometer observations from the crossing of the tail magnetopause at an antisolar distance of close to 100 R(E) through exit into the solar wind on the dayside. We link these measurements with correlative data from ground stations and from IMP 8 which was ideally located to serve as a monitor of the solar wind upstream of the bow shock. Based on our analysis, we present a time line of the important geomagnetic events of the day that we believe provides a framework for the full multi-instrument analysis of the flyby data. In this paper we use the observations to investigate aspects of the relationship between magnetotail dynamics and the separate intensifications of a multiple onset substorm inferred from ground-based data. The spacecraft spent 6 h downstream of lunar orbit, of which more than 4 h were spent outside of the plasma sheet in regions where traveling compressional regions (TCRs) should have been apparent. Although six substorm intensifications were recorded on the ground during this interval, we did not observe a detectable TCR or plasmoid for every intensification. Our interpretation has important implications for the description of substorm dynamics in the tail. We propose that the signatures associated with individual substorm intensifications are localized in dawn-to-dusk extent even at remote locations in the magnetotail, just as they are in the ionosphere, and that the tail disturbances associated with successive substorm intensifications step across the tail towards the dusk flank. This latter interpretation is appealing as it can explain the failure of Galileo to observe a signature associated with each intensification without invalidating the conclusion of ISEE 3 investigators that in the same region of the magnetotail at least one signature can be associated with each substorm viewed as a collection of individual intensifications. Plasmoidlike signatures with strong axial fields along the GSM y axis and parallel to the B(y) of the interplanetary magnetic field (IMF) were present when the spacecraft was embedded close to the center of the plasma sheet. We interpret these signatures as flux ropes, that is, twisted magnetic structures with one end possibly tied to the ionosphere. The modeled structure yields j x B/jB much greater than 1 which suggests that the flux ropes are magnetically force free to within the limitations of the model. We point out that plasmoids and flux ropes form a continuum of structures distinguished by the magnitude of B(y). Our observations lend additional support to the view that bipolar B(z) signatures in the magnetotail may often be better described as flux ropes than as disconnected plasmoids. Our other principal results are only summarized in this paper; they will be discussed in greater detail elsewhere. They include (1) additional evidence that the IMF B(y) controls the lobe magnetic field only in the quadrants that are magnetically linked to the solar wind, and (2) evidence that the low-frequency response (the classic ''sudden impulse'' or SI signature) to a solar wind shock can be absent in the magnetic signature obtained within a high beta plasma sheet. We believe that these observations will provide insight useful for improving phenomenological models of substorms. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02140. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. NATL RES COUNCIL CANADA,HERZBERG INST ASTROPHYS,OTTAWA K1A 0R6,ONTARIO,CANADA. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. RP KIVELSON, MG (reprint author), UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,SLICHTER HALL,LOS ANGELES,CA 90024, USA. RI Kivelson, Margaret/I-9019-2012 OI Kivelson, Margaret/0000-0003-3859-8581 NR 28 TC 41 Z9 43 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1993 VL 98 IS A7 BP 11299 EP 11318 DI 10.1029/92JA03001 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LL822 UT WOS:A1993LL82200015 ER PT J AU SONG, P RUSSELL, CT FITZENREITER, RJ GOSLING, JT THOMSEN, MF MITCHELL, DG FUSELIER, SA PARKS, GK ANDERSON, RR HUBERT, D AF SONG, P RUSSELL, CT FITZENREITER, RJ GOSLING, JT THOMSEN, MF MITCHELL, DG FUSELIER, SA PARKS, GK ANDERSON, RR HUBERT, D TI STRUCTURE AND PROPERTIES OF THE SUBSOLAR MAGNETOPAUSE FOR NORTHWARD INTERPLANETARY MAGNETIC-FIELD - MULTIPLE-INSTRUMENT PARTICLE OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LATITUDE BOUNDARY-LAYER; DAYSIDE MAGNETOPAUSE; ELECTRIC-FIELDS; ION COMPOSITION; ISEE 1; PLASMA; MAGNETOSPHERE; RECONNECTION; MAGNETOSHEATH; ACCELERATION AB The structure and properties of the subsolar magnetopause for northward interplanetary magnetic field (IMF) are studied with measurements from 10 different instruments for three ISEE crossings. Data show that the overall structure and properties are similar for the three crossings, indicating the magnetopause is relatively well determined in the subsolar region for strongly northward IMF. The measurements from different instruments are consistent with each other and complementary based on the current knowledge of space plasma physics. The combined data set suggests that the magnetopause region is best organized by defining a sheath transition layer and steplike boundary layers. The sheath transition layer contains mostly magnetosheath particles. The magnetosheath, magnetospheric, and ionospheric populations are mixed in the interior boundary layers. This result, which is consistent with previous studies, is now supported by observations of a much broader spectrum of measurements including three-dimensional electron, energetic particle, heavy ion and plasma wave. Some new features are also found: even for quiet subsolar magnetopause crossings, transient or small-scale structures still occur sporadically; slight heating may occur in the boundary layers. Some outstanding issues are clarified by this study: the electron flux enhancements in the lowest energies in the boundary layers and magnetosphere are ionospheric electrons and not photoelectrons from the spacecraft; for northward IMF, they are photoelectrons, but for southward IMF they may be secondary electrons; and the density measurements from differential and integral techniques are similar, leaving no room for a significant ''invisible'' population. C1 UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. OBSERV PARIS,DEPT RECH SPATIALE,F-92195 MEUDON,FRANCE. JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. UNIV WASHINGTON,SEATTLE,WA 98195. RP SONG, P (reprint author), NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,POB 3000,BOULDER,CO 80307, USA. NR 59 TC 75 Z9 77 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1993 VL 98 IS A7 BP 11319 EP 11337 DI 10.1029/93JA00606 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LL822 UT WOS:A1993LL82200016 ER PT J AU MENIETTI, JD SMITH, MF AF MENIETTI, JD SMITH, MF TI INVERTED VS SPANNING THE CUSP BOUNDARY-LAYER SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FLUX-TRANSFER EVENTS; WIND ENERGY-TRANSFER; PLASMA INJECTION; ELECTRON-PRECIPITATION; MAGNETOSHEATH PLASMA; POLAR CUSP; MAGNETOSPHERE; PENETRATION; SIMULATION; REGIONS AB We present several examples of dayside inverted Vs in which ion convention and energy dispersion appear to span the region of both open and closed field lines. All of these examples occur in the region generally called the low-latitude boundary layer or the cusp boundary layer and suggest a connection between closed field lines of the dayside auroral region and open field lines of the dayside cusp. One explanation is that plasma in the cusp boundary layer on closed field lines convects across field lines in a smooth fashion into the cusp. Such cross-field-line convection may be possible in regions of finite conductivity and strong currents, where the field can diffuse through the plasma. Another explanation for the observations is that they represent the mid-altitude manifestation of merging at the dayside magnetopause and the opening of previously closed field lines. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. SW RES INST,DEPT SPACE SCI,SAN ANTONIO,TX 78284. RP MENIETTI, JD (reprint author), UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242, USA. NR 25 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1993 VL 98 IS A7 BP 11391 EP 11400 DI 10.1029/92JA02563 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LL822 UT WOS:A1993LL82200022 ER PT J AU WILSON, RM AF WILSON, RM TI ON THE VARIATION OF THE SUNS X-RAY-BACKGROUND FLUX AND ITS RELATION TO THE SUNS FLARING RATE, ENERGETIC EVENT RATE, AND THE SOLAR-CYCLE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RADIO FLUX AB Daily averages of the Sun's X ray background flux as measured by the GOES satellite are combined to yield monthly means and ''smoothed'' monthly means (12-month moving averages) for the interval January 1986 through May 1992 (minimum, rise, maximum. and initial decline of solar cycle 22). These averages are then compared directly to the Sun's optical flaring rate, energetic event rate, and the usual markers of the solar cycle (e.g., sunspot number, total corrected sunspot area, 10.7-cm solar radio flux number of groups and number of spots). The results of this analysis support previous findings that there exists a remarkably close positive relationship between the optical flaring rate and the X ray background flux mte (the independent variable); that the relationship is best described using a logarithmic fit of the form y = a + blog(1 + x); and that the X ray background flux rate can be used as a proxy for the solar cycle. Additionally, this study has found that a strong positive relationship exists between the energetic event rate and the X ray background flux rate (the independent variable), being best described by a linear fit of the form y = a + bx; that the lag between the maxima of the rates of optical flaring and X ray background flux reported for cycle 21 did not recur for cycle 22; and that the lag for cycle 21 and lack of lag for cycle 22 can easily be explained by the peculiar action of the solar cycle, especially as it relates to the phasing of the ''magnetic complexity'' of active regions (i.e., the particular phasing of the numbers of groups and spots). RP WILSON, RM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES52,HUNTSVILLE,AL 35812, USA. NR 10 TC 14 Z9 14 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1993 VL 98 IS A7 BP 11477 EP 11482 DI 10.1029/93JA00307 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LL822 UT WOS:A1993LL82200030 ER PT J AU QUINN, RD YUNIS, IS AF QUINN, RD YUNIS, IS TI CONTROL-STRUCTURE INTERACTIONS OF SPACE STATION SOLAR DYNAMIC MODULES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Potential control/structures interaction problems of large flexible multibody structures in the presence of pointing and tracking requirements are addressed. A control approach is introduced for the simultaneous tracking and vibration control of multibody space structures. The application that is discussed is the planned Space Station Freedom configured with solar dynamic modules. The solar dynamic fine-pointing and tracking requirements may necessitate controller frequencies above the structural natural frequencies of space station and the solar dynamic modules themselves. It is well known that this can give rise to control/structure interaction problems if the controller is designed without giving due consideration to the structural dynamics of the system. Possible control/structure interaction problems of Freedom's solar dynamic power systems are investigated. A finite element model of Freedom is used to demonstrate these potential control/structure interaction problems and the proposed tracking and vibration control approach. C1 NASA,LEWIS RES CTR,STRUCT SYST DYNAM BRANCH,CLEVELAND,OH 44135. RP QUINN, RD (reprint author), CASE WESTERN RESERVE UNIV,DEPT MECH & AEROSP ENGN,CLEVELAND,OH 44106, USA. NR 12 TC 2 Z9 2 U1 2 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1993 VL 16 IS 4 BP 623 EP 629 DI 10.2514/3.21059 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LM739 UT WOS:A1993LM73900003 ER PT J AU TROUDET, T GARG, S MERRILL, W AF TROUDET, T GARG, S MERRILL, W TI NEUROCONTROL DESIGN AND ANALYSIS FOR A MULTIVARIABLE AIRCRAFT CONTROL PROBLEM SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB The feasibility of using artificial neural networks as control systems for modern, complex aerospace vehicles is investigated via an aircraft control design study. The problem considered is that of designing a controller for an integrated airframe/propulsion longitudinal dynamics model of a modern fighter aircraft to provide independent control of pitch rate and airspeed responses to pilot command inputs. An explicit model-following controller using H(infinity) control design techniques is first designed to gain insight into the control problem as well as to provide a baseline for evaluation of the neurocontroller. Using the model of the desired dynamics as a command generator, a multilayer feedforward neural network is trained to control the vehicle model within the physical limitations of the actuator dynamics. This is achieved by minimizing an objective function that is a weighted sum of tracking errors and control input commands and rates. To gain insight into the neurocontrol design, linearized representations of the neurocontroller are analyzed along a commanded trajectory. Linear robustness analysis tools are then applied to the linearized neurocontroller models and to the baseline H(infinity) based controller. Robustness issues of the neurocontrol design are identified and addressed in the context of neural training. Future areas of research are identified to enhance the practical applicability of neural networks to flight control design. C1 NASA,LEWIS RES CTR,ADV CONTROLS TECHNOL BRANCH,CLEVELAND,OH 44135. RP TROUDET, T (reprint author), SVERDRUP TECHNOL INC,DEPT STRUCT & MAT,BROOKPARK,OH 44142, USA. NR 21 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1993 VL 16 IS 4 BP 738 EP 747 DI 10.2514/3.21075 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LM739 UT WOS:A1993LM73900019 ER PT J AU BELBRUNO, EA MILLER, JK AF BELBRUNO, EA MILLER, JK TI SUN-PERTURBED EARTH-TO-MOON TRANSFERS WITH BALLISTIC CAPTURE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A method is described for constructing a new type of low energy transfer trajectory from the Earth to the moon leading to ballistic capture. This is accomplished by utilizing the nonlinear Earth-moon-sun perturbations on a point mass in three dimensions. The interaction of the gravitational fields of the bodies defines transition regions in the position-velocity space where the dynamic effects on the point mass tend to balance. These are termed week stability boundaries. The transfer is obtained by the use of trajectories connecting the weak stability boundaries. It uses approximately 18% less DELTAV than the Hohmann transfer to insert a spacecraft into a circular orbit about the moon. The use of this transfer has recently been demonstrated by Japan's Hiten spacecraft, which arrived at the moon on October 2, 1991. Application of the transfer method is also made to the Lunar Observer Mission. C1 JET PROP LAB,NAVIGAT SECT,PASADENA,CA 91109. RP BELBRUNO, EA (reprint author), JET PROP LAB,MISS DESIGN SECT,MS 301-140H,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 170 Z9 186 U1 2 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1993 VL 16 IS 4 BP 770 EP 775 DI 10.2514/3.21079 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LM739 UT WOS:A1993LM73900023 ER PT J AU VIKRAM, CS WITHEROW, WK TROLINGER, JD AF VIKRAM, CS WITHEROW, WK TROLINGER, JD TI SPECIAL BEAM INTENSITY RATIO NEEDS IN MULTICOLOR HOLOGRAPHY SO JOURNAL OF MODERN OPTICS LA English DT Article AB The special beam intensity ratio needs in superimposed holograms due to multiple colours are described. The reduced reference to object beam intensity ratio requirement can enhance the reconstruction efficiency reduced because of the multiplexing process. The feasibility is described along with examples of some two- and three-colour cases. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. METROLASER,IRVINE,CA 92714. RP VIKRAM, CS (reprint author), UNIV ALABAMA,CTR APPL OPT,HUNTSVILLE,AL 35899, USA. NR 9 TC 3 Z9 3 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0950-0340 J9 J MOD OPTIC JI J. Mod. Opt. PD JUL PY 1993 VL 40 IS 7 BP 1387 EP 1393 DI 10.1080/09500349314551421 PG 7 WC Optics SC Optics GA LQ911 UT WOS:A1993LQ91100011 ER PT J AU MARTIN, JML LEE, TJ TAYLOR, PR AF MARTIN, JML LEE, TJ TAYLOR, PR TI AN ACCURATE AB-INITIO QUARTIC FORCE-FIELD FOR FORMALDEHYDE AND ITS ISOTOPOMERS SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID QUADRATIC CONFIGURATION-INTERACTION; VIBRATIONAL-ENERGY LEVELS; MOLECULAR CALCULATIONS; TRIPLE EXCITATIONS; BASIS SETS; SPECTROSCOPY; CONSTANTS; SPECTRA; SINGLES; ATOMS C1 LIMBURGS UNIV CENTRUM,DEPT SBG,B-3590 DIEPENBEEK,BELGIUM. UNIV INSTELLING ANTWERP,INST MAT SCI,DEPT CHEM,B-2610 WILRIJK,BELGIUM. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP MARTIN, JML (reprint author), SAN DIEGO SUPERCOMP CTR,POB 85608,SAN DIEGO,CA 92186, USA. RI Lee, Timothy/K-2838-2012; Martin, Jan/A-7457-2008 OI Martin, Jan/0000-0002-0005-5074 NR 41 TC 100 Z9 100 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUL PY 1993 VL 160 IS 1 BP 105 EP 116 DI 10.1006/jmsp.1993.1161 PG 12 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA LJ188 UT WOS:A1993LJ18800009 ER PT J AU HILL, EL MARTIN, RB GUNTHER, E MOREYHOLTON, E HOLETS, VR AF HILL, EL MARTIN, RB GUNTHER, E MOREYHOLTON, E HOLETS, VR TI CHANGES IN BONE IN A MODEL OF SPINAL-CORD INJURY SO JOURNAL OF ORTHOPAEDIC RESEARCH LA English DT Article ID VASOACTIVE INTESTINAL PEPTIDE; IMMUNOREACTIVE NERVES; RAT; TRANSECTION; PERIOSTEUM; OSTEOPOROSIS; DENSITY; FIBERS; CELLS; ADULT AB Bone calcium, histomorphometry, and mechanical strength were evaluated in a model of spinal cord injury. Cortical bone area and rates of formation and apposition at the tibiofibular junction (TFJ) and midshaft of the humerus were measured at 35-42, 42-77, and 77-94 days after transection of the spinal cord. All comparisons were between the animals with a spinal lesion and control animals. A 0.34% difference in the length of the tibia of the two groups of animals was observed, the dry weight of the tibia was 28.4% less in rats with a lesion, and there was no significant difference in the amount of calcium per milligram of bone. At 35 days after surgery, the cortical area in the midshaft of the humerus was slightly less (11%) in rats with a lesion, but by 94 days there was no difference in cortical or medullary area. Tle final (day 94) cortical area at the TFJ in rats with a lesion was less than that in the controls. Bone formation at the TFJ was similar in both groups in the period of 35-42 days and was similar at 77-94 days in the animals with a lesion, and rates of formation and apposition were greater in the humerus of rats with a lesion; the rates did not differ significantly between groups at either site. At 94 days, trabecular bone area in the tibial metaphysis was 41% less in rats with a lesion. Mechanical parameters were significantly less in the femora, but not the humeri, of rats with a lesion. C1 UNIV MIAMI,SCH MED,DEPT CELL BIOL & ANAT,MIAMI PROJECT,1600 NW 10TH AVE R-48,MIAMI,FL 33136. UNIV CALIF DAVIS,ORTHOPAED RES LAB,DAVIS,CA 95616. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV MIAMI,SCH MED,DEPT NEUROL SURG,MIAMI,FL 33136. FU NIAMS NIH HHS [AR 41347] NR 41 TC 20 Z9 21 U1 0 U2 0 PU JOURNAL BONE JOINT SURGERY INC PI NEEDHAM PA 20 PICKERING ST, NEEDHAM, MA 02192 SN 0736-0266 J9 J ORTHOPAED RES JI J. Orthop. Res. PD JUL PY 1993 VL 11 IS 4 BP 537 EP 547 DI 10.1002/jor.1100110408 PG 11 WC Orthopedics SC Orthopedics GA LQ688 UT WOS:A1993LQ68800007 PM 8340826 ER PT J AU ZUBE, DM MYERS, RM AF ZUBE, DM MYERS, RM TI THERMAL NONEQUILIBRIUM IN A LOW-POWER ARCJET NOZZLE SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Emission spectroscopy measurements were made of the plasma flow inside the nozzle of a 1-kW-class arcjet thruster. The thruster propellant was a hydrogen-nitrogen mixture used to simulate fully decomposed hydrazine. Several 0.25-mm-diam holes were drilled into the 12-mm-long diverging section of the tungsten thruster nozzle to provide side-on optical access to the internal flow. Electron excitation for atomic species and molecular vibrational and rotational temperatures were determined for the expanding plasma using relative line ratio techniques. The atomic excitation temperature decreased from 18,000 K at a location 3-mm downstream of the constrictor to 9000 K at a location 9 mm from the constrictor, while the molecular vibrational and rotational temperatures decreased from 6500 to 3000 K and 8000 to 3000 K, respectively, between the same locations. The electron density, measured using H(beta) line Stark broadening, decreased from almost-equal-to 10(21) m-3 to 2 x 10(20) m-3 during the expansion in the nozzle. The results show that the plasma is in a nonequilibrium state throughout most of the nozzle, with relaxation times close to or larger than the particle residence time. C1 SVERDRUP TECHNOL INC,NASA,LEWIS RES CTR GRP,CLEVELAND,OH 44135. RP ZUBE, DM (reprint author), UNIV STUTTGART,INST RAUMFAHRTSYST,W-7000 STUTTGART 80,GERMANY. NR 31 TC 24 Z9 27 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1993 VL 9 IS 4 BP 545 EP 552 DI 10.2514/3.23657 PG 8 WC Engineering, Aerospace SC Engineering GA LN143 UT WOS:A1993LN14300007 ER PT J AU ARNONE, A LIOU, MS POVINELLI, LA AF ARNONE, A LIOU, MS POVINELLI, LA TI MULTIGRID CALCULATION OF 3-DIMENSIONAL VISCOUS CASCADE FLOWS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A three-dimensional code for viscous cascade flow prediction has been developed. The space discretization uses a cell-centered scheme with eigenvalue scaling to weigh the artificial dissipation terms. Computational efficiency of a four-stage Runge-Kutta scheme is enhanced hy using variable coefficients, implicit residual smoothing, and a full-multigrid method. The Baldwin-Lomax eddy-viscosity model is used for turbulence closure. A zonal, nonperiodic grid is used to minimize mesh distortion in and downstream of the throat region. Applications are presented for an annular vane with and without end wall contouring, and for a large-scale linear cascade. The calculation is validated by comparing with experiments and by studying grid dependency. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. RP ARNONE, A (reprint author), UNIV FLORENCE,DEPT ENERGY ENG,VIA S MARTA 3,I-50139 FLORENCE,ITALY. OI Arnone, Andrea/0000-0001-7471-4442 NR 24 TC 20 Z9 21 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1993 VL 9 IS 4 BP 605 EP 614 DI 10.2514/3.23664 PG 10 WC Engineering, Aerospace SC Engineering GA LN143 UT WOS:A1993LN14300014 ER PT J AU PENKO, PF BOYD, ID MEISSNER, DL DEWITT, KJ AF PENKO, PF BOYD, ID MEISSNER, DL DEWITT, KJ TI MEASUREMENT AND ANALYSIS OF A SMALL NOZZLE PLUME IN VACUUM SO JOURNAL OF PROPULSION AND POWER LA English DT Note ID DENSITY C1 CORNELL UNIV,ITHACA,NY 14853. UNIV TOLEDO,TOLEDO,OH 43606. RP PENKO, PF (reprint author), NASA,LEWIS RES CTR,M-S SPTD-1,CLEVELAND,OH 44135, USA. NR 5 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1993 VL 9 IS 4 BP 646 EP 648 DI 10.2514/3.23670 PG 3 WC Engineering, Aerospace SC Engineering GA LN143 UT WOS:A1993LN14300020 ER PT J AU BENNER, DC DEVI, VM SMITH, MAH RINSLAND, CP AF BENNER, DC DEVI, VM SMITH, MAH RINSLAND, CP TI AIR-BROADENING, N2-BROADENING, AND O2-BROADENING AND SHIFT COEFFICIENTS IN THE NU-3 SPECTRAL REGION OF (CH4)-C-12 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID INDUCED LINE SHIFTS; LORENTZ WIDTH; HALF-WIDTHS; METHANE; BAND; PARAMETERS; NU-3-BAND AB Pressure-broadening and pressure-induced shift coefficients have been measured for more than 450 transitions in the nu3 region of (CH4)-C-12, between 2650 and 3200 cm-1. The results were obtained by analyzing 29 room-temperature laboratory absorption spectra recorded with 0.01-cm-1 resolution using the McMath Fourier transform spectrometer of the National Solar Observatory (NSO). Absorption cells with path lengths of 5, 25, and 150 cm, sample pressures of 60-550 torr, and CH4 volume mixing ratios of 0.01 or less in dry air, N2 or O2 were used. The broadening and shift coefficients were determined using a nonlinear least-squares spectrum fitting technique. Absorption lines belonging to nu3, nu2 + nu4, 2nu4(2) and 2nu2(2) bands of (CH4)-C-12 were observed in the spectra. Transitions up to J'' = 17 in the nu3, J'' = 12 in the nu2 + nu4, J'' = 9 in the 2nu4(2) and J'' = 4 in the 2nu2(2) bands were included in the analysis. Variations of the measured parameters with tetrahedral symmetry species and rotational quantum numbers of the transitions involved are discussed. Comparisons of the retrieved parameters in various bands in both (CH4)-C-12 and (CH4)-C-13 are performed in order to determine the extent of vibrational dependence. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. RP BENNER, DC (reprint author), COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23187, USA. NR 26 TC 32 Z9 32 U1 0 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JUL PY 1993 VL 50 IS 1 BP 65 EP 89 PG 25 WC Optics; Spectroscopy SC Optics; Spectroscopy GA LJ391 UT WOS:A1993LJ39100009 ER PT J AU TSAI, LW TAHMASEBI, F AF TSAI, LW TAHMASEBI, F TI SYNTHESIS AND ANALYSIS OF A NEW CLASS OF 6-DEGREE-OF-FREEDOM PARALLEL MINIMANIPULATORS SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article ID STEWART PLATFORM; MANIPULATOR; DESIGN; WORKSPACE; MECHANISM AB A new class of 6-degree-of-freedom (dof) parallel minimanipulators is introduced. The minimanipulators are designed to provide high resolution and high stiffness for fine position and force control in a hybrid serial-parallel manipulator system. Two-dof planar linkages and inextensible limbs are used to improve positional resolution and stiffness of the minimanipulators. The 2-dof linkages serve as drivers for the minimanipulators. The minimanipulators require only three inextensible limbs and, unlike most of the six-limbed parallel manipulators, their direct kinematics can be reduced to solving a polynomial in a single variable. In addition, by using three limbs instead of six other benefits such as lower possibility of mechanical interference between limbs can be realized. All of the minimanipulator actuators are base-mounted. As a result, higher payload capacity, smaller actuator sizes, and lower power dissipation can be obtained. In addition to the design discussion, kinematic analysis of the minimanipulators is also presented. C1 UNIV MARYLAND, SYST RES CTR, COLL PK, MD 20742 USA. NASA, GODDARD SPACE FLIGHT CTR, ROBOT BRANCH, GREENBELT, MD 20771 USA. RP UNIV MARYLAND, DEPT MECH ENGN, COLL PK, MD 20742 USA. NR 20 TC 41 Z9 44 U1 3 U2 7 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 JUL PY 1993 VL 10 IS 5 BP 561 EP 580 DI 10.1002/rob.4620100503 PG 20 WC Robotics SC Robotics GA LG775 UT WOS:A1993LG77500002 ER PT J AU NGUYEN, CC ANTRAZI, SS ZHOU, ZL CAMPBELL, CE AF NGUYEN, CC ANTRAZI, SS ZHOU, ZL CAMPBELL, CE TI ADAPTIVE-CONTROL OF A STEWART PLATFORM-BASED MANIPULATOR SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article AB This article presents the implementation of a joint-space adaptive control scheme used to control noncompliant motion of a Stewart platform-based manipulator (SPBM) that is used in a facility called the Hardware Real-Time Emulator (HRTE) developed at Goddard Space Flight Center to emulate space operations. The SPBM is comprised of two platforms and six linear actuators driven by dc motors, and possesses six degrees of freedom. The article briefly reviews the development of the adaptive control scheme, which is composed of proportional-derivative (PD) controllers whose gains are adjusted by an adaptation law driven by the errors between the desired and actual trajectories of the SPBM actuator lengths. The derivation of the adaptation law is based on the concept of model reference adaptive control (MRAC) and Lyapunov direct method under the assumption that SPBM motion is slow as compared to the controller adaptation rate. An experimental study is conducted to evaluate the performance of the adaptive control scheme implemented to control the SPBM to track a vertical and circular paths under step changes in payload. Experimental results show that the adaptive control scheme provides superior tracking capability as compared to fixed-gain controllers. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP NGUYEN, CC (reprint author), CATHOLIC UNIV AMER,DEPT ELECT ENGN,ROBOT & CONTROL LAB,WASHINGTON,DC 20064, USA. NR 28 TC 84 Z9 90 U1 0 U2 4 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD JUL PY 1993 VL 10 IS 5 BP 657 EP 687 DI 10.1002/rob.4620100507 PG 31 WC Robotics SC Robotics GA LG775 UT WOS:A1993LG77500006 ER PT J AU WEILMUENSTER, KJ GNOFFO, PA AF WEILMUENSTER, KJ GNOFFO, PA TI SOLUTION STRATEGY FOR 3-DIMENSIONAL CONFIGURATIONS AT HYPERSONIC SPEEDS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID FLIGHT EXPERIMENT AB A procedure that reduces the memory requirements for computing the viscous flow over a modified Orbiter geometry at a hypersonic flight condition is presented. The Langley aerothermodynamic upwind relaxation algorithm (LAURA) code, that which incorporates a thermochemical nonequilibrium chemistry model, a finite rate catalytic wall boundary condition, and wall temperature distribution based on radiation equilibrium, is used in this study. In addition, the effect of choice of second-order flux formulations, eigenvalue limiter, and grid density on surface heating is investigated. The surface heating from a flowfield calculation at Mach number 22, altitude of 230,000 ft, and 40-deg angle of attack is compared with flight data from three Orbiter flights. RP WEILMUENSTER, KJ (reprint author), NASA LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 29 TC 9 Z9 9 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 385 EP 394 DI 10.2514/3.25543 PG 10 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400001 ER PT J AU GUPTA, RN LEE, KP ZOBY, EV AF GUPTA, RN LEE, KP ZOBY, EV TI ENHANCEMENTS TO VISCOUS-SHOCK-LAYER TECHNIQUE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID REYNOLDS-NUMBER FLOWS; LONG SLENDER BODIES AB A solution procedure is presented that considerably improves the computational efficiency of the viscous-shock-layer technique, especially for long slender bodies. The ''predictor-corrector'' procedure suggested for obtaining the shock shape beyond the nose region requires only a single global pass. The accuracy of the present method is demonstrated by comparison with globally iterated results over the entire body and with ground- and flight-test data. The new procedure results in computer run times one-third to one-half of the times required for the full-body global iteration procedure. Furthermore, the algebraic expressions used to specify the initial shock shape eliminate the need for a shock shape generated by external means and permit immediate introduction of the full viscous-shock-layer equations. C1 VIGYAN INC,HAMPTON,VA 23666. RP GUPTA, RN (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 35 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 404 EP 413 DI 10.2514/3.25545 PG 10 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400003 ER PT J AU DESAI, PN BUGLIA, JJ AF DESAI, PN BUGLIA, JJ TI DETERMINING MARS PARKING ORBITS THAT ENSURE TANGENTIAL PERIAPSIS BURNS AT ARRIVAL AND DEPARTURE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB For a manned Mars mission, many previous interplanetary studies have arbitrarily assumed that the required parking orbit can be achieved with tangential periapsis burns at both Mars arrival and departure without considering the actual arrival and departure orbital geometries. As a consequence of this assumption, a misleading estimate of up to 50% of the initial low-Earth-orbit mass may result for the mission. In this paper, a method is presented that finds Mars parking orbits that allow tangential periapsis burns at both arrival and departure. This method accounts for the actual geometry at both arrival and departure between the hyperbolic asymptotes and the orbital plane, along with the precession effects caused by the oblateness of Mars. Thus, realistic DELTAV values (and hence initial low-Earth-orbit masses) are obtained for these orbits. The results obtained from the present method compare very well with a trajectory integration program and require CPU times of only about 1 min. Therefore, because of its computational efficiency and accuracy, the present method would be an ideal tool to use in preliminary mission design, since it provides the opportunity to incorporate realistic Mars parking orbits effects. C1 FLIGHT MECH & CONTROL INC,HAMPTON,VA 23666. RP DESAI, PN (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23666, USA. NR 16 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 414 EP 419 DI 10.2514/3.25546 PG 6 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400004 ER PT J AU STRIEPE, SA BRAUN, RD POWELL, RW FOWLER, WT AF STRIEPE, SA BRAUN, RD POWELL, RW FOWLER, WT TI INFLUENCE OF INTERPLANETARY TRAJECTORY SELECTION ON EARTH ATMOSPHERIC ENTRY VELOCITY OF MARS MISSIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Many current manned Mars mission studies are using low lift-to-drag ratio vehicles to aerobrake at both Mars and Earth. This paper will demonstrate that if entry velocity constraints are incorporated into the interplanetary analysis of aerobraking Mars missions, more opportunities can be achieved for only a small increase in initial mass in low-Earth orbit (IMLEO). These additional opportunities result from varying the initial launch date and the encounter dates and possibly using a powered Venus swingby on either the inbound or outbound transfer. This paper not only presents unconstrained entry velocity missions but also includes results for entry velocities below 12.5 and 14 km/s on Earth return and between 6.0-8.5 km/s at Mars arrival. The results indicate that, regardless of the Mars entry velocity range selected, an Earth entry velocity below 14 km/s is easily attainable for a minimal IMLEO increase. Although there are fewer 12.5 km/s Earth entry velocity missions possible, both Mars entry velocity constraint cases have over 50% of their missions requiring a negligible IMLEO increase. C1 UNIV TEXAS,DEPT AEROSP ENGN & ENGN MECH,AUSTIN,TX 78712. RP STRIEPE, SA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23681, USA. NR 9 TC 6 Z9 6 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 420 EP 425 DI 10.2514/3.25547 PG 6 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400005 ER PT J AU STRIEPE, SA BRAUN, RD POWELL, RW FOWLER, WT AF STRIEPE, SA BRAUN, RD POWELL, RW FOWLER, WT TI INFLUENCE OF INTERPLANETARY TRAJECTORY SELECTION ON MARS ATMOSPHERIC ENTRY VELOCITY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Many current manned Mars mission studies are using low lift-to-drag ratio (L/D) vehicles to aerobrake at both Mars and Earth. The use of these low LID vehicles could limit the allowable velocity at the atmospheric interface. This paper will demonstrate that if entry velocity constraints are incorporated into the interplanetary analysis of aerobraking Mars missions, many opportunities can be achieved for a small increase in initial mass in low-Earth orbit (IMLEO). These opportunities result from varying the initial launch date and the encounter dates and possibly using a powered Venus swingby on either the inbound or outbound transfer. This paper demonstrates this technique by using three atmospheric entry velocity ranges at Mars arrival (6.0-8.5, 6.4-8.1, and 7.2-7.3 km/s), unconstrained Mars entry velocities, and an Earth return entry velocity below 14 km/s. The results indicate that, by carefully selecting the interplanetary trajectory, an optimum IMLEO mission can be found for even highly restrictive entry velocity missions in practically all of the 15 yr studied. C1 UNIV TEXAS,DEPT AEROSP ENGN & ENGN MECH,AUSTIN,TX 78712. RP STRIEPE, SA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23681, USA. NR 6 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 426 EP 430 DI 10.2514/3.25548 PG 5 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400006 ER PT J AU TAUBER, M HENLINE, W CHARGIN, M PAPADOPOULOS, P CHEN, Y YANG, L HAMM, K AF TAUBER, M HENLINE, W CHARGIN, M PAPADOPOULOS, P CHEN, Y YANG, L HAMM, K TI MARS ENVIRONMENTAL SURVEY PROBE AEROBRAKE PRELIMINARY DESIGN STUDY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The objective of this study is to design aerobrakes for the Mars Environmental Survey (MESUR) vehicles. To contain cost, existing flight-certified materials are considered for the structure and heatshield. Since the probes enter the atmosphere directly, the heatshields had to survive entry during duststorm conditions. A slightly modified Viking forebody shape, consisting of a blunted 70-deg cone, is used. An aluminum honeycomb shell is used for the structure. For the nominal 7-km/s entry, the heatshield material used on the Vikings (a silicone elastomeric charring ablator, SLA-561) was found to be lightest, yielding an aerobrake mass fraction of 13.2%. For the extreme case of entry at 9 km/s, the stagnation region heatshield consisted of the medium-density ablator AVCOAT-5026, used on the Apollo capsules, and SLA-561 was used on the conical skirt. The aerobrake mass fraction for the 9-km/s entry was 18%. The penalty resulting if a single conservatively designed aerobrake were used for both entry velocities could reach 4.8% of the entry mass at 7 km/s. Therefore, it is recommended that separate aerobrakes be designed for probes entering at 7 km/s and at 9 km/s. C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. ELORET INST,PALO ALTO,CA 94303. STERLING SOFTWARE,PALO ALTO,CA 94303. RP TAUBER, M (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 16 TC 9 Z9 9 U1 1 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 431 EP 437 DI 10.2514/3.25549 PG 7 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400007 ER PT J AU THROCKMORTON, DA AF THROCKMORTON, DA TI SHUTTLE ENTRY AEROTHERMODYNAMIC FLIGHT RESEARCH - THE ORBITER EXPERIMENTS PROGRAM SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID ACCELEROMETER PACKAGE EXPERIMENT; HEAT-TRANSFER DATA AB Routine operations of the nation's Space Transportation System have provided recurring opportunities for aerothermodynamicists to study entry aerothermal phenomena unique to lifting entry vehicles in hypersonic flight. Initiated in the mid-1970s, the Orbiter Experiments (OEX) Program provided a mechanisms for utilization of the Shuttle Orbiter as an entry research vehicle as an adjunct to it normal operational mission. The data derived from OEX Program experiments represent benchmark hypersonic night results heretofore unavailable for a lifting entry vehicle. These data are being used in a continual process of validation of state-of-the-art methods, both experimental and computational, for simulating and/or predicting the aerothermodynamic flight characteristics of advanced space transportation vehicles. The OEX Program complement of research experiments is described, typical flight data obtained by these experiments are presented, and utilization of these data for validation of advanced vehicle aerothermodynamic design tools is demonstrated. RP THROCKMORTON, DA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 47 TC 2 Z9 2 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 449 EP 465 DI 10.2514/3.25551 PG 17 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400009 ER PT J AU WHITE, SM BURLEIGH, D AF WHITE, SM BURLEIGH, D TI INFRARED THERMOGRAPHIC TECHNIQUES FOR ARC-JET TESTING SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Thermography can be used to image materials in the infrared range and to produce two-dimensional maps of surface temperatures of materials in extreme environments and under harsh experimental conditions where directly measuring the surface temperature with probes at all desired locations is either difficult or impossible. Thermography is a process for measuring the surface radiant energy and reducing it to a temperature map of the surface. Until recently quantitative temperature data for arc-jet tests were not easily achievable by thermographic techniques. To obtain quantifiable results, experimenters need reliable effective values for the emittance of the radiating surface, the transmittance of any intervening windows or other media, and the bandpass of any filters. In a new approach, these properties were lumped together and evaluated by integrating the relevant temperature-dependent spectral properties and using the experimental data from a limited set of surface thermocouples. This approach was validated by the good agreement between different surface thermocouples and temperatures derived from thermographic measurements. Thermographic monitoring of a series of arc-jet tests is described. The thermographic data gathered are used to evaluate the heating distribution across the surface of the test model as well as the effect of steps in the model surface on the surface temperature. C1 GEN DYNAM CORP,DIV SPACE SYST,SAN DIEGO,CA 92186. RP WHITE, SM (reprint author), NASA,AMES RES CTR,THERMAL PROTECT MAT BRANCH,MAIL STOP 234-1,MOFFETT FIELD,CA 94035, USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 477 EP 483 DI 10.2514/3.25553 PG 7 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400011 ER PT J AU HILLARD, GB FERGUSON, DC AF HILLARD, GB FERGUSON, DC TI SOLAR-ARRAY MODULE PLASMA INTERACTIONS EXPERIMENT (SAMPIE) - SCIENCE AND TECHNOLOGY OBJECTIVES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID EARTH-ORBIT PLASMA AB The solar array module plasma interactions experiment (SAMPIE) is an approved NASA flight experiment manifested for Shuttle deployment in early 1994. The SAMPIE experiment is designed to investigate the interaction of high voltage space power systems with ionospheric plasma. To study the behavior of solar cells, a number of solar cell coupons (representing design technologies of current interest) will be biased to high voltages to measure both arcing and current collection. Various theories of arc suppression will be tested by including several specially modified cell coupons. Finally, SAMPIE will include experiments to study the basic nature of arcing and current collection. This paper describes the rationale for a space flight experiment, the measurements to be made, and the significance of the expected results. A future paper will present a detailed discussion of the engineering design. RP HILLARD, GB (reprint author), NASA,LEWIS RES CTR,SPACE ENVIRONM EFFECTS BRANCH,CLEVELAND,OH 44135, USA. NR 25 TC 10 Z9 11 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 488 EP 494 DI 10.2514/3.25555 PG 7 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400013 ER PT J AU BRODY, AR ELLIS, SR GRUNWALD, A HAINES, RF AF BRODY, AR ELLIS, SR GRUNWALD, A HAINES, RF TI INTERACTIVE DISPLAYS FOR TRAJECTORY PLANNING AND PROXIMITY OPERATIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Rendezvous, docking, and other Space Station proximity operations (PROX OPS) will be conducted routinely in space. Real-time interactive visual aids and planning tools will be helpful, if not necessary, for future missions both in preflight training and on orbit. Two such displays, eivaN and Navie, are currently available for examination and human factors testing. A study was conducted in which data were collected from eight test subjects. Solution times for both devices decreased rapidly with experience. Neither fuel usage nor the number of waypoints (burns) decreased with experience. With Navie, medians of solution time and fuel consumption totaled over all subjects peaked at one of two starting points above the V-bar with monotonically decreasing values in both directions. This pattern did not appear with eivaN values. Since the docking tasks were fundamentally different with each device, and because Navie imposed more constraints on the users than eivaN did, the orbital mechanics effects had a more pronounced effect on the Navie results than on the eivaN data. C1 NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,SPACECRAFT DATA SYST RES BRANCH,MOFFETT FIELD,CA 94035. RP BRODY, AR (reprint author), NASA,AMES RES CTR,STERLING SOFTWARE,BIOL FLIGHT RES PROJECT OFF,MS 244-19,MOFFETT FIELD,CA 94035, USA. NR 13 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1993 VL 30 IS 4 BP 514 EP 518 DI 10.2514/3.25559 PG 5 WC Engineering, Aerospace SC Engineering GA LR714 UT WOS:A1993LR71400017 ER PT J AU WENZEL, EM ARRUDA, M KISTLER, DJ WIGHTMAN, FL AF WENZEL, EM ARRUDA, M KISTLER, DJ WIGHTMAN, FL TI LOCALIZATION USING NONINDIVIDUALIZED HEAD-RELATED TRANSFER-FUNCTIONS SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article ID SOUND LOCALIZATION; HEADPHONE SIMULATION; AUDITORY SPACE; SPECTRAL CUES; PLANE; TOPOGRAPHY; ACUITY AB A recent development in human-computer interfaces is the virtual acoustic display, a device that synthesizes three-dimensional, spatial auditory information over headphones using digital filters constructed from head-related transfer functions (HRTFs). The utility of such a display depends on the accuracy with which listeners can localize virtual sound sources. A previous study [F. L. Wightman and D. J. Kistler, J. Acoust. Soc. Am. 85, 868-878 (1989)] observed accurate localization by listeners for free-field sources and for virtual sources generated from the subjects' own HRTFs. In practice, measurement of the HRTFs of each potential user of a spatial auditory display may not be feasible. Thus, a critical research question is whether listeners can obtain adequate localization cues from stimuli based on nonindividualized transforms. Here, inexperienced listeners judged the apparent direction (azimuth and elevation) of wideband noisebursts presented in the free-field or over headphones; headphone stimuli were synthesized using HRTFs from a representative subject of Wightman and Kistler. When confusions were resolved, localization of virtual sources was quite accurate and comparable to the free-field sources for 12 of the 16 subjects. Of the remaining subjects, 2 showed poor elevation accuracy in both stimulus conditions, and 2 showed degraded elevation accuracy with virtual sources. Many of the listeners also showed high rates of front-back and up-down confusions that increased significantly for virtual sources compared to the free-field stimuli. These data suggest that while the interaural cues to horizontal location are robust, the spectral cues considered important for resolving location along a particular cone-of-confusion are distorted by a synthesis process that uses nonindividualized HRTFs. C1 UNIV WISCONSIN,WAISMAN CTR,MADISON,WI 53705. UNIV WISCONSIN,DEPT PSYCHOL,MADISON,WI 53705. RP WENZEL, EM (reprint author), NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MAIL STOP 262-2,MOFFETT FIELD,CA 94035, USA. NR 39 TC 378 Z9 387 U1 7 U2 26 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD JUL PY 1993 VL 94 IS 1 BP 111 EP 123 DI 10.1121/1.407089 PG 13 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA LL825 UT WOS:A1993LL82500013 PM 8354753 ER PT J AU SRINIVASAN, GR RAGHAVAN, V DUQUE, EPN MCCROSKEY, WJ AF SRINIVASAN, GR RAGHAVAN, V DUQUE, EPN MCCROSKEY, WJ TI FLOWFIELD ANALYSIS OF MODERN HELICOPTER ROTORS IN HOVER BY NAVIER-STOKES METHOD SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article ID BLADE; FLOW AB The viscous, three-dimensional flowfields of UH-60A and BERP rotors are calculated for lifting hover configurations using a Navier-Stokes computational fluid dynamics method, called TURNS, with a view to understand the importance of planform effects on the airloads. The solution scheme is essentially a free-wake method. That is, the induced effects of the wake, including the interaction of tip vortices with successive blades, are captured as a part of the overall flowfield solution without prescribing the structure or position of the vortical wake. However, the structure of the captured tip vortex is diffused by numerical viscosity. Calculated results are presented for the UH-60A and BERP rotors in the form of surface pressures, hover performance parameters, surface particle flow, tip vortex, and vortex wake trajectory at two thrust conditions. The results for the UH-60A model rotor agree well with experiments for a moderate thrust condition. Comparison of UH-60A results with an equivalent rectangular UH-60A blade and a high-twist BERP blade indicates that the BERP blade, with an unconventional planform, produces more thrust at a given collective pitch, and approximately the same Figure of Merit. The high thrust conditions considered produce severe shock-induced flow separation for the UH-60A blade, while the BERP blade develops more thrust and minimal separation. The BERP blade produces a tighter tip vortex structure compared with the UH-60A blade. These results and the discussion presented bring out the similarities and differences between the two rotors. C1 JAI ASSOCIATES INC,MT VIEW,CA 94042. STERLING SOFTWARE INC,FED SYST GRP,PALO ALTO,CA. USA,AEROFLIGHTDYNAM DIRECTORATE,MOFFETT FIELD,CA 94035. RP SRINIVASAN, GR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 26 Z9 29 U1 0 U2 1 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1993 VL 38 IS 3 BP 3 EP 13 PG 11 WC Engineering, Aerospace SC Engineering GA ME845 UT WOS:A1993ME84500001 ER PT J AU VISINTAINER, JA MARCOLINI, MA BURLEY, CL LIU, SR AF VISINTAINER, JA MARCOLINI, MA BURLEY, CL LIU, SR TI ACOUSTIC PREDICTIONS USING MEASURED PRESSURES FROM A MODEL ROTOR IN THE DNW SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB A contemporary design, 4-bladed United Technologies model rotor with pressure-instrumented blades was tested in the Duits-Nederlandse Windtunnel. Simultaneous acoustic and pressure measurements were made for a wide range of operating conditions. Microphones were positioned at a number of locations in the flow forward of the rotor to measure rotor thickness noise and high-speed impulsive noise (in the rotor plane), and blade-vortex interaction noise (forward and below the rotor plane). The blade surface pressure data are used as aerodynamic input to WOPWOP, which is a rotor noise prediction program that predicts thickness and loading noise. The predicted results using WOPWOP are compared to the measured noise levels for cases where either the noise, blade-vortex interaction noise, or high-speed impulsive noise is the dominant noise mechanism. The comparisons show regions of good agreement, as well as areas where further improvement is necessary. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. USA,AEROFLIGHTDYNAM DIRECTORATE,MOFFETT FIELD,CA. RP VISINTAINER, JA (reprint author), UNITED TECHNOL CORP,SIKORSKY AIRCRAFT DIV,STRATFORD,CT 06601, USA. NR 18 TC 8 Z9 8 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1993 VL 38 IS 3 BP 35 EP 44 PG 10 WC Engineering, Aerospace SC Engineering GA ME845 UT WOS:A1993ME84500004 ER PT J AU BROOKS, TF BOOTH, ER AF BROOKS, TF BOOTH, ER TI THE EFFECTS OF HIGHER HARMONIC CONTROL ON BLADE-VORTEX INTERACTION NOISE AND VIBRATION SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article ID MODEL-ROTOR; REDUCTION AB A rotor acoustics test was conducted to examine the use of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) noise. A dynamically scaled, four-bladed, articulated rotor model was tested in a heavy gas (R-12) medium in Langley's Transonic Dynamics Tunnel. Acoustic and vibration measurements were made for a large range of matched flight conditions where prescribed (open loop) HHC pitch schedules were superimposed on the normal (baseline) collective and cyclic trim pitch. A new sound power measurement technique was developed to take advantage of the reverberant field in the hard walled tunnel. Special calibrations permit straightforward acoustic scaling of the results to those one would obtain in air. Quantitative sound power results are presented for a 4/rev (4P) collective pitch HHC. By comparing the results using 4P HHC to corresponding baseline (no HHC) conditions, significant mid-frequency noise reductions of 5-6 dB are found for low-speed descent conditions where BVI is most intense. For other flight conditions, noise is found to increase with the use of HHC. Low frequency loading noise, as well as fixed and rotating frame vibration levels, showed increased levels with HHC. RP BROOKS, TF (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 12 TC 2 Z9 2 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1993 VL 38 IS 3 BP 45 EP 55 PG 11 WC Engineering, Aerospace SC Engineering GA ME845 UT WOS:A1993ME84500005 ER PT J AU YEAGER, WT MIRICK, PH HAMOUDA, MNH WILBUR, ML SINGLETON, JD WILKIE, WK AF YEAGER, WT MIRICK, PH HAMOUDA, MNH WILBUR, ML SINGLETON, JD WILKIE, WK TI ROTORCRAFT AEROELASTIC TESTING IN THE LANGLEY TRANSONIC DYNAMICS TUNNEL SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Wind-tunnel testing of a properly scaled aeroelastic model helicopter rotor is considered critical to the design and development of new rotor systems. For this reason, extensive testing or aeroelastically scaled model rotors is done in the Transonic Dynamics Tunnel (TDT) located at the Langley Research Center. A unique capability of this facility, which enables proper dynamic scaling, is the use of difluorodichloromethane, or Refrigerant-12 (R-12) as a test medium. The paper presents a description of the TDT and a discussion of the benefits of using R-12 as a test medium. A description of the system used to conduct model tests is provided, as well as examples of typical rotor tests conducted in the TDT. RP YEAGER, WT (reprint author), USA,VEHICLE STRUCT DIRECTORATE,NASA,LANGLEY RES CTR,HAMPTON,VA, USA. NR 25 TC 1 Z9 1 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1993 VL 38 IS 3 BP 73 EP 82 PG 10 WC Engineering, Aerospace SC Engineering GA ME845 UT WOS:A1993ME84500008 ER PT J AU LYNE, JE BRAUN, RD AF LYNE, JE BRAUN, RD TI FLEXIBLE STRATEGIES FOR MANNED MARS MISSIONS USING AEROBRAKING AND NUCLEAR THERMAL PROPULSION SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB This study examined previously described Mars mission scenarios for the years 2014, 2016, 2018, and 2020 for vehicles using aerobraking (AB), nuclear thermal propulsion (NTP), and a combination of the two technologies. Each launch opportunity evaluated allowed for a nominal, long-duration (similar to 600 day) surface stay, a mission abort after a short surface stay (10 to 65 days), and a swingby abort with no Mars landing. The initial mass required in low Earth orbit (IMLEO) for the spacecraft to be able to execute any of these three options was determined for each combination of launch year and vehicle design (chemical propulsion with aerobraking (CHEM/AB), NTP and NTP/AB). The principal findings of the investigation were: 1) Viable mission abort opportunities exist for vehicles that use chemical propulsion with aerobraking without exceeding 1000 metric tons. 2) In most cases, these abort strategies do not cause atmospheric entry velocities to exceed previously recommended limits for the aerocapture of low lift to drag ratio (L/D) vehicles. The exceptions are minor and possibly could be eliminated with further manipulation of mission dates. 3) Significant reductions in IMLEO occur when vehicles which use nuclear propulsion employ aerobraking for the Mars orbit insertion; on average, a specific impulse (I-sp) of 1100 seconds (corresponding to advanced technology NTP) would be required for all-propulsive designs to match the IMLEO of systems which use present technology NTP (I-sp = 825 s) in conjunction with aerobraking at Mars. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP LYNE, JE (reprint author), UNIV TENNESSEE,KNOXVILLE,TN, USA. RI Lyne, James/E-6363-2011 NR 9 TC 6 Z9 6 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD JUL-SEP PY 1993 VL 41 IS 3 BP 339 EP 347 PG 9 WC Engineering, Aerospace SC Engineering GA MG705 UT WOS:A1993MG70500004 ER PT J AU DECOU, AB AF DECOU, AB TI ATTITUDE AND TETHER VIBRATION CONTROL IN SPINNING TETHERED TRIANGLES FOR ORBITING INTERFEROMETRY SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article ID SPACECRAFT AB The dynamics and control problems associated with an Earth orbiting system consisting of three identical tethered masses at the corners of an equilateral triangle spinning around an arbitrary axis is studied. The objective is to demonstrate the feasibility of controlling an optical astronomical interferometer consisting of three telescopes at the corners and one at the center with fiber optics in the tethers to bring the radiation to a combining station. The control problems are divided into two parts. First, the system is analyzed as a rigid spinning triangle with gravity gradient disturbance torques. A control strategy is derived which will maintain the orientation of the triangle and/or slew the spin axis between arbitrary directions on the celestial sphere, using continuous thrusting at the corners provided by ion thrusters. Second, the accuracy of the rigid body assumption is estimated by determining the disturbing forces acting on the tethers (gravity gradient, inertial, and solar radiation pressure) and the resulting vibrations. A method of damping these vibrations is suggested and preliminary estimates of its effectiveness are carried out by computer modeling. I conclude that multi-year missions of this type are possible with available ion thrusters, but more work is needed on the tether damping. C1 JET PROP LAB,PASADENA,CA. RP DECOU, AB (reprint author), NO ARIZONA UNIV,FLAGSTAFF,AZ 86011, USA. NR 11 TC 14 Z9 15 U1 0 U2 1 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD JUL-SEP PY 1993 VL 41 IS 3 BP 373 EP 398 PG 26 WC Engineering, Aerospace SC Engineering GA MG705 UT WOS:A1993MG70500006 ER EF