FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Wang, J Lee, PCY Bailey, DH AF Wang, J Lee, PCY Bailey, DH TI Thickness-shear and flexural vibrations of linearly contoured crystal strips with multiprecision computation SO COMPUTERS & STRUCTURES LA English DT Article DE mindlin; plate; crystal; resonator; strip; vibration; thickness-shear; frequency; coupling; multiprecision ID QUARTZ RESONATORS AB The effect of linear contouring of crystal strips on the resonance frequencies, the coupling among vibration modes, and the spatial variation of mode shapes have attracted analytical and experimental studies for many decades for its application in crystal resonator design. In the present paper, exact solutions are obtained for the coupled thickness-shear and flexural vibrations of quartz strips with linearly varying thickness by the Frobenius method. Four special functions in terms of infinite power series are obtained from which displacements and stresses can be derived. The efficient and precise evaluation of these functions is aided by a multiprecision program. Frequency spectra and mode shapes are computed for various parameters of crystal strip resonators with beveled edges. Some important effects of contouring are discussed from these results. (C) 1999 Elsevier Science Ltd. Ail rights reserved. C1 Princeton Univ, Dept Civil Engn & Operat Res, Princeton, NJ 08544 USA. NASA, Ames Res Ctr, NAS Appl Res Branch, Moffett Field, CA 94035 USA. RP Wang, J (reprint author), Princeton Univ, Dept Civil Engn & Operat Res, Princeton, NJ 08544 USA. EM jiwang@erd.epson.com NR 15 TC 24 Z9 24 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD FEB PY 1999 VL 70 IS 4 BP 437 EP 445 DI 10.1016/S0045-7949(98)00189-8 PG 9 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA 167EB UT WOS:000078618700005 ER PT J AU Bjorndal, KA Wetherall, JA Bolten, AB Mortimer, JA AF Bjorndal, KA Wetherall, JA Bolten, AB Mortimer, JA TI Twenty-six years of green turtle nesting at Tortuguero, Costa Rica: An encouraging trend SO CONSERVATION BIOLOGY LA English DT Article ID LONG-LIVED ORGANISMS; CHELONIA-MYDAS; SEA-TURTLES; MANAGEMENT; DEMOGRAPHICS; CONSERVATION; POPULATION; FISHERIES; MODEL AB The green turtle (Chelonia mydas) population that nests at Tortuguero, Costa Rica, is the largest in the Atlantic by at least an order of magnitude. Surveys to monitor the nesting activity on the northern 18 km of the 36-km beach were initiated in 1971 and extended to the entire beach in 1986. Front the survey data, we estimated the total number of nesting emergences on the northern 18 km for each year from 1971 through 1996. Evaluation of the trend in nesting emergences indicated a relatively consistent increase from 1971 to the mid-1980s, constant or perhaps decreasing nesting during the late 1980s, and then resumption of an upward trend in the 1990s. Evaluation of trends in sea turtle nesting populations requires many years of data because of the large degree of annual variation in nesting numbers The trends reported in this study must be evaluated with caution for several reasons. First, if the the mean number of nests deposited by each female each year (clutch frequency) varies significantly among years, changes in the number of nesting emergences among years could reflect changes in the number of nesting females, clutch frequency, or both. Second, we only assessed the trend in one segment of the population (mature females), which may or may not represent the trend of the entire green turtle population and which, because of late maturity, may not reflect changes in juvenile mortality for many years. Third, survey frequency, and thus confidence in annual estimates varied among years. The upward population trend must be assessed from the perspective of the catastrophic decline that the Caribbean green turtle populations have experienced since the arrival of Europeans. If careful management is continued in Costa Rica and adopted throughout the region,the collapse of the Caribbean green turtle populations-which seemed imminent in the 1950s-can be avoided. C1 Univ Florida, Dept Zool, Gainesville, FL 32611 USA. Univ Florida, Archie Carr Ctr Sea Turtle Res, Gainesville, FL 32611 USA. Natl Marine Fisheries Serv, Honolulu, HI 96822 USA. Caribbean Conservat Corp, Gainesville, FL 32609 USA. RP Bjorndal, KA (reprint author), Univ Florida, Dept Zool, POB 118525, Gainesville, FL 32611 USA. EM kab@zoo.ufl.edu OI Mortimer, Jeanne A./0000-0001-6318-2890; Bjorndal, Karen/0000-0002-6286-1901 NR 35 TC 86 Z9 92 U1 2 U2 22 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0888-8892 EI 1523-1739 J9 CONSERV BIOL JI Conserv. Biol. PD FEB PY 1999 VL 13 IS 1 BP 126 EP 134 DI 10.1046/j.1523-1739.1999.97329.x PG 9 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 161CN UT WOS:000078271000016 ER PT J AU Stiling, P Rossi, AM Hungate, B Dijkstra, P Hinkle, CR Knott, WM Drake, B AF Stiling, P Rossi, AM Hungate, B Dijkstra, P Hinkle, CR Knott, WM Drake, B TI Decreased leaf-miner abundance in elevated CO2: Reduced leaf quality and increased parasitoid attack SO ECOLOGICAL APPLICATIONS LA English DT Article DE carbon; nitrogen ratios; field experiment; herbivore-enemy interactions; increased leaf consumption; increased parasitism; plant-herbivore interactions; plant nitrogen; CO2, response to elevation in ID INSECT HERBIVORE INTERACTIONS; ATMOSPHERIC CO2; CARBON-DIOXIDE; DECIDUOUS TREES; PERFORMANCE; PLANTS; DENSITY; PHYTOCHEMISTRY; LEPIDOPTERA; POPULATION AB Most studies on the effects of elevated CO2 have focused on the effects on plant growth and ecosystem processes. Fewer studies have examined the effects of elevated CO2 on herbivory, and of these, most have examined feeding rates in laboratory conditions. Our study takes advantage of an open-top CO2 fertilization study in a Florida scrub-oak community to examine the effects of elevated CO2 on herbivore densities, herbivore feedings rates, and levels of attack of herbivores by natural enemies. Higher atmospheric CO2 concentration reduced plant foliar nitrogen concentrations, decreased abundance of leaf-mining insect herbivores, increased per capita leaf consumption by leafminers, and increased leaf miner mortality. As suggested by other authors, reduced foliar quality contributed to the increase in herbivore mortality, but only partly. The major factor increasing mortality was higher attack rate by parasitoids. Thus increasing CO2 concentrations may reduce the survivorship of insect herbivores directly, by reducing plant quality, but also indirectly, by changing herbivore feeding and eliciting greater top-down pressure from natural enemies. C1 Univ S Florida, Dept Biol, Tampa, FL 33620 USA. Smithsonian Environm Res Ctr, Edgewater, MD 21037 USA. Dynamac Corp, NASA, Kennedy Space Ctr, FL 32899 USA. NASA, Kennedy Space Ctr, FL 32899 USA. RP Stiling, P (reprint author), Univ S Florida, Dept Biol, Tampa, FL 33620 USA. RI Hungate, Bruce/F-8991-2011 OI Hungate, Bruce/0000-0002-7337-1887 FU NIDCR NIH HHS [DEB 9633717] NR 35 TC 90 Z9 94 U1 8 U2 33 PU ECOLOGICAL SOC AMER PI WASHINGTON PA 1707 H ST NW, STE 400, WASHINGTON, DC 20006-3915 USA SN 1051-0761 J9 ECOL APPL JI Ecol. Appl. PD FEB PY 1999 VL 9 IS 1 BP 240 EP 244 DI 10.2307/2641182 PG 5 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA 169FM UT WOS:000078736900022 PM 11543430 ER PT J AU Cole, MW Hubbard, C Fountzoulas, CG Demaree, D Natarajan, A Miller, RA Zhu, D Xie, K AF Cole, MW Hubbard, C Fountzoulas, CG Demaree, D Natarajan, A Miller, RA Zhu, D Xie, K TI The reliability of Ni contacts to n-SiC subjected to pulsed thermal fatigue SO ELECTROCHEMICAL AND SOLID STATE LETTERS LA English DT Article ID OHMIC CONTACT; GAAS AB Laboratory experiments which mimic the acute cyclic thermal loading characteristic of pulsed power device switching operation have been developed. Ni contacts to n-SiC were the device components selected for cyclic thermal testing. Modifications of the contact-SiC materials properties in response to cyclic thermal fatigue were quantitatively assessed via Rutherford backscattering spectrometry, nanoindentation testing, and current-voltage measurements. Decreases in nanohardness and elastic modulus were observed in response to thermal fatigue. No compositional modifications were observed at the metal- semiconductor interface. Our results demonstrated that the majority of the material changes were initiated after the first thermal pulse and that the effects of subsequent thermal cycling (up to 10 pulses) were negligible. The stability of the metal- semiconductor interface after exposure to repeated pulsed thermal cycling lends support for the utilization of Ni as a contact metallization for pulsed power switching applications. (C) 1999 The Electrochemical Society. S1099- 0062( 98) 09- 049- X. All rights reserved. C1 USA, Res Lab, Weap & Mat Res Directorate, Aberdeen Proving Ground, MD 21005 USA. Johns Hopkins Univ, Dept Mat Sci & Engn, Baltimore, MD 21213 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Anadig, Warren, NJ 07069 USA. RP Cole, MW (reprint author), USA, Res Lab, Weap & Mat Res Directorate, Aberdeen Proving Ground, MD 21005 USA. EM mcole@arl.mil NR 16 TC 13 Z9 14 U1 0 U2 2 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 65 SOUTH MAIN STREET, PENNINGTON, NJ 08534 USA SN 1099-0062 J9 ELECTROCHEM SOLID ST JI Electrochem. Solid State Lett. PD FEB PY 1999 VL 2 IS 2 BP 97 EP 99 DI 10.1149/1.1390747 PG 3 WC Electrochemistry; Materials Science, Multidisciplinary SC Electrochemistry; Materials Science GA 185YE UT WOS:000079697800016 ER PT J AU Hadland, PH Balasubramaniam, R Wozniak, G Subramanian, RS AF Hadland, PH Balasubramaniam, R Wozniak, G Subramanian, RS TI Thermocapillary migration of bubbles and drops at moderate to large Marangoni number and moderate Reynolds number in reduced gravity SO EXPERIMENTS IN FLUIDS LA English DT Article ID GRADIENT; MOTION AB Results from experiments on the thermocapillary migration of air bubbles and Fluorinert drops in a Dow-Coming silicone oil aboard a NASA Space Shuttle mission are presented and discussed. The experiments cover a wider range of Marangoni and Reynolds numbers than that attained in a prior flight experiment. The data are consistent with earlier results, and are compared with theoretical predictions. Large air bubbles were found to deform slightly in shape to oblate spheroids while the deformation of even the largest drops was within the uncertainty of the size measurements. C1 Clarkson Univ, Dept Chem Engn, Potsdam, NY 13699 USA. NASA, Lewis Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. Freiberg Univ Min & Technol, Inst Fluidmech & Fluidenergiemaschinen, D-09596 Freiberg, Germany. RP Clarkson Univ, Dept Chem Engn, Potsdam, NY 13699 USA. NR 19 TC 54 Z9 62 U1 3 U2 10 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0723-4864 EI 1432-1114 J9 EXP FLUIDS JI Exp. Fluids PD FEB PY 1999 VL 26 IS 3 BP 240 EP 248 DI 10.1007/s003480050285 PG 9 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 169EN UT WOS:000078734700009 ER PT J AU Goldmeer, JS T'ien, JS Urban, DL AF Goldmeer, JS T'ien, JS Urban, DL TI Combustion and extinction of PMMA cylinders during depressurization in low-gravity SO FIRE SAFETY JOURNAL LA English DT Article ID FLAME AB Combustion and extinction behavior of a diffusion flame over polymethyl methacrylate (PMMA) cylinders during depressurization in low gravity are examined experimentally and via numerical simulations. Low-gravity conditions were obtained using the NASA Lewis Research Center's reduced-gravity aircraft. Effects of reduced pressure and transient depressurization on the visible flame are examined. The flammability of the burning solid is determined as a function of pressure and solid phase center temperature at constant velocity; as the solid-phase temperature increases, the extinction pressure decreases. The numerical model assumes a two-dimensional model with a quasi-steady gas phase and an unsteady solid phase. A parametric study is conducted to examine the effects of forced flow, heating of the solid phase, and depressurization rates on the extinction boundary. One case with conditions similar to the low-gravity aircraft experiments is presented in detail. The predicted extinction boundaries from the parametric study are quasi-steady in nature and could be relevant to the International Space Station's fire fighting scenario. Published by Elsevier Science Ltd. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Mech & Aerosp Engn, Cleveland, OH 44106 USA. RP Goldmeer, JS (reprint author), NASA, Lewis Res Ctr, MS 500-115,21000 Brookpark Rd, Cleveland, OH 44135 USA. EM jef-frey.goldmeer@lerc.nasa.gov NR 23 TC 13 Z9 14 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0379-7112 J9 FIRE SAFETY J JI Fire Saf. J. PD FEB PY 1999 VL 32 IS 1 BP 61 EP 88 DI 10.1016/S0379-7112(98)00017-4 PG 28 WC Engineering, Civil; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 161VH UT WOS:000078310000004 ER PT J AU Steele, HM Drdla, K Turco, RP Lumpe, JD Bevilacqua, RM AF Steele, HM Drdla, K Turco, RP Lumpe, JD Bevilacqua, RM TI Tracking polar stratospheric cloud development with POAM II and a microphysical model SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SIZE DISTRIBUTIONS; SULFATE AEROSOLS; AIRBORNE LIDAR; LIQUID; GROWTH; OZONE AB The formation and development of polar stratospheric clouds are examined using a comprehensive microphysical model applied along air parcel trajectories. During Antarctic winter specific parcels are sampled over a time span of several days using extinction data from the POAM II satellite instrument. The observed evolution of polar stratospheric cloud spectral opacity is compared to predictions from model simulations. Hence, aerosol growth and decay in response to changing environmental conditions can be observed and interpreted. In some instances good agreement between observations and predictions has been obtained over periods of many days. The analysis provides evidence for the role of temperature history in cloud formation and properties, in agreement with previous studies. On occasion, the apparent behavior of a PSC along a trajectory is inconsistent with current theoretical concepts. C1 Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. USN, Res Lab, Remote Sensing Div, Washington, DC 20375 USA. NASA, Ames Res Ctr, Atmospher Phys Branch, Moffett Field, CA 94035 USA. Computat Phys Inc, Fairfax, VA 22301 USA. RP Steele, HM (reprint author), Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England. NR 24 TC 5 Z9 5 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 1999 VL 26 IS 3 BP 287 EP 290 DI 10.1029/1998GL900324 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 163YK UT WOS:000078434300002 ER PT J AU Chang, CP Lin, SC Liou, CS Liu, WT AF Chang, CP Lin, SC Liou, CS Liu, WT TI An experiment using NSCAT winds in the numerical prediction of tropical mesoscale rainfall systems under the influence of terrain SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEASAT SCATTEROMETER WINDS; IMPACT; MODEL; PARAMETERIZATION AB The rich mesoscale information in NSCAT winds over tropical coastal regions is used in numerical simulations of two June 1997 monsoonal cases occurring over Taiwan. It is shown that transient NSCAT mesoscale information over a localized area as small as 120 km x 240 km can result in significant improvement in the 24 h heavy rainfall forecast due to its effect on monsoonal convection and terrain effects. C1 USN, Postgrad Sch, Monterey, CA 93943 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chang, CP (reprint author), USN, Postgrad Sch, Code MR CP, Monterey, CA 93943 USA. EM cpchang@nps.navy.mil; sclin@cc.ncu.edu.tw; liou@nrlmry.nav.mil; liu@pacific.jpl.nasa.gov NR 14 TC 1 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 1999 VL 26 IS 3 BP 311 EP 314 DI 10.1029/1998GL900299 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 163YK UT WOS:000078434300008 ER PT J AU Garvin, JB Frawley, JJ Abshire, JB AF Garvin, JB Frawley, JJ Abshire, JB TI Vertical roughness of Mars from the Mars Orbiter Laser Altimeter SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TOPOGRAPHY AB The vertical roughness of the martian surface at similar to 250 m spatial scales has been determined in two global latitude bands: an equatorial and a high northern band acquired from 18 tracks of data by the Mars Orbiter Laser Altimeter (MOLA) during the Fall of 1997. The distribution of RMS vertical roughness, as derived from MOLA pulse widths, for the equatorial band is non-gaussian, with an overall mean of 2.8 m RMS, but with secondary populations at 1.5 m and 2 - 6 m RMS. The higher latitude northern plains of Mars are almost uniformly similar to 1 m RMS in their vertical roughness characteristics, suggesting that they are smoother than virtually any terrestrial deserts. We suggest that dust mantling has muted the local topography of Mars, rendering it as smooth as 1-2 m RMS. Heavily cratered uplands near the martian equator are noticeably rougher, indicating more rugged and less-mantled local topography. C1 NASA, Goddard Space Flight Ctr, Geodynam Branch, Terr Phys Lab, Greenbelt, MD 20771 USA. Herring Bay Geophys, Tracys Landing, MD USA. RP Garvin, JB (reprint author), NASA, Goddard Space Flight Ctr, Geodynam Branch, Terr Phys Lab, Mail Code 921, Greenbelt, MD 20771 USA. RI Abshire, James/I-2800-2013 NR 7 TC 24 Z9 24 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 1999 VL 26 IS 3 BP 381 EP 384 DI 10.1029/1998GL900309 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 163YK UT WOS:000078434300026 ER PT J AU Higgins, CA Thieman, JR Fung, SF Green, JL Candey, RM AF Higgins, CA Thieman, JR Fung, SF Green, JL Candey, RM TI Jovian dual-sinusoidal HOM lane features observed by Galileo SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RADIO EMISSIONS; JUPITERS AB A well defined sinusoidal-shaped "band" of reduced emission intensity exists within Jovian HOM from 500 kHz to 3 MHz at all Jovian longitudes as observed by the Galileo spacecraft. A less prominent sinusoidal-shaped band feature exists in the same frequency range but is 180 degrees out of phase with the more prominent feature. We used a multiple Jovian rotation spectrogram technique to fully display both bands and found that these sinusoidal-shaped features are the source of the "lanes" previously studied in Voyager and Ulysses data. Our extension of the simple straight-line ray model by Gurnett et al. [1998] provides a qualitative explanation for the observed features. We found that the two sinusoidal bands show an asymmetry about the longitude of the northern tip of the magnetic dipole (202 degrees CML). Enhancements of emission can be seen along the edges of the bands which may be interpreted as caustic surfaces. C1 NASA, Goddard Space Flight Ctr, NRC, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Space Sci Data Operat Off, Greenbelt, MD 20771 USA. RP Higgins, CA (reprint author), NASA, Goddard Space Flight Ctr, NRC, Code 633-0, Greenbelt, MD 20771 USA. RI Candey, Robert/D-4639-2012; Fung, Shing/F-5647-2012 NR 10 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 1999 VL 26 IS 3 BP 389 EP 392 DI 10.1029/1998GL900302 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 163YK UT WOS:000078434300028 ER PT J AU Reiner, MJ Kaiser, ML AF Reiner, MJ Kaiser, ML TI Complex type III-like radio emissions observed from 1 to 14 MHz SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BURSTS AB We present a morphological description of intense, complex type III-like radio emissions in the frequency range from 1 to 14 MHz. This previously unexplored frequency range, between ground-based and space-based observations, corresponds to the transition region (heliocentric distances from similar to 2 to 10 R.) between the solar corona and interplanetary medium. The complex type III-like radio emissions, some of which are SA events [Cane et al., 1981], are found to have distinctly different radio signatures above and below similar to 7 MHz. Above similar to 7 MHz, the radio emissions consists of very rapid frequency-drifting structures with time scales of <16 seconds. Below similar to 7 MHz, the radio emissions generally blend into slower frequency-drifting type III-like substructures, with the addition of short-duration very narrowband features that are either very slowly frequency drifting or nondrifting. In addition, there is generally a clear diminution in the radio intensity near 7 MHz. C1 Raytheon ITSS, Lanham, MD 20706 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Reiner, MJ (reprint author), Raytheon ITSS, 4000 Forbes Blvd, Lanham, MD 20706 USA. EM reiner@urap.gsfc.nasa.gov; kaiser@lepmlk.gsfc.nasa.gov NR 8 TC 34 Z9 34 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 1999 VL 26 IS 3 BP 397 EP 400 DI 10.1029/1998GL900317 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 163YK UT WOS:000078434300030 ER PT J AU Osherovich, VA Fainberg, J Stone, RG AF Osherovich, VA Fainberg, J Stone, RG TI Multi-tube model for interplanetary magnetic clouds SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EIGENVALUE SOLUTIONS; FILAMENTS AB Measurements of the polytropic index gamma inside a magnetic cloud showed that there are two non-equal tubes inside the cloud [Fainberg et al., 1996; Osherovich et al., 1997]. For both tubes, gamma < 1, but each tube has its own polytrope. We test equilibrium solutions which are a superposition of solutions with cylindrical and helical symmetry [Krat and Osherovich, 1978] as a new paradigm for a multi-tube model. Comparison of magnetic and gas pressure profiles for these bounded MHD states with observations suggests that complex magnetic clouds can be viewed as multiple helices embedded in a cylindrically symmetric flux rope. C1 NASA, Goddard Space Flight Ctr, Raytheon STX, Greenbelt, MD 20771 USA. RP Osherovich, VA (reprint author), NASA, Goddard Space Flight Ctr, Raytheon STX, Code 690-2, Greenbelt, MD 20771 USA. EM vladimir@urap.gsfc.nasa.gov; joseph.fainberg@gsfc.nasa.gov; stone@urap.gsfc.nasa.gov NR 21 TC 33 Z9 33 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 1999 VL 26 IS 3 BP 401 EP 404 DI 10.1029/1998GL900306 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 163YK UT WOS:000078434300031 ER PT J AU Cattell, CA Dombeck, J Wygant, JR Hudson, MK Mozer, FS Temerin, MA Peterson, WK Kletzing, CA Russell, CT Pfaff, RF AF Cattell, CA Dombeck, J Wygant, JR Hudson, MK Mozer, FS Temerin, MA Peterson, WK Kletzing, CA Russell, CT Pfaff, RF TI Comparisons of Polar satellite observations of solitary wave velocities in the plasma sheet boundary and the high altitude cusp to those in the auroral zone SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WEAK DOUBLE-LAYERS; ACCELERATION REGION AB Characteristics of solitary waves observed by Polar in the high altitude cusp, polar cap and plasma sheet boundary are reported and compared to observations in the auroral zone. The study presented herein shows that, at high altitudes, the solitary waves are positive potential structures (electron holes), with scale sizes of the order of 10's of Debye lengths, which usually propagate with velocities of a few thousand km/s. At the plasma sheet boundary, the direction of propagation can be either upward or downward; whereas at the leading edge of high altitude cusp energetic particle injections, it is downward. For these high altitude events, explanations based on ion modes and on electron modes are both examined, and the electron mode interpretation is shown to be more consistent with observations. C1 Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Lockheed Martin Res Lab, Palo Alto, CA USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Cattell, CA (reprint author), Univ Minnesota, Sch Phys & Astron, 116 Church St SE, Minneapolis, MN 55455 USA. RI Pfaff, Robert/F-5703-2012; Peterson, WK/A-8706-2009; OI Pfaff, Robert/0000-0002-4881-9715; Peterson, WK/0000-0002-1513-6096; Cattell, Cynthia/0000-0002-3805-320X; Kletzing, Craig/0000-0002-4136-3348; Russell, Christopher/0000-0003-1639-8298 NR 24 TC 130 Z9 130 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 1999 VL 26 IS 3 BP 425 EP 428 DI 10.1029/1998GL900304 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 163YK UT WOS:000078434300037 ER PT J AU Moses, JI Rawlins, K Zahnle, K Dones, L AF Moses, JI Rawlins, K Zahnle, K Dones, L TI External sources of water for Mercury's putative ice deposits SO ICARUS LA English DT Article ID SHORT-PERIOD COMETS; POLAR ANOMALIES; SOLAR-SYSTEM; ASTEROIDS; STABILITY; OBJECTS; PLANETS; IMPACT; EARTH; MOON AB Radar images have revealed the possible presence of ice deposits in Mercury's polar regions. Although thermal models indicate that watts ice can be stable in permanently shaded regions near Mercury's poles, the ultimate source of the water remains unclear. We use stochastic models and other theoretical methods to investigate the role of external sources in supplying Mercury with the requisite amount of water. By extrapolating the current terrestrial influx of interplanetary dust particles to that at Mercury, we find that continual micrometeoritic bombardment of Mercury over the last 3.5 byr could have resulted in the delivery of (3-60) x 10(16) g of water ice to tb permanently shaded regions at Mercury's poles (equivalent to an average ice thickness of 0.8-20 m), Erosion by micrometeoritic impact on exposed ice deposits could reduce the above value by about a half. For comparison, the current ice deposits on Mercury are believed to be somewhere between similar to 2 and 20 m thick. Using a Monte Carlo model to simulate the impact history of Mercury, we find that asteroids and comets can also deliver an amount of water consistent with the observations. Impacts from Jupiter-family comets over the last 3.5 billion years can supply (0.1-200) x 10(16) g of water to Mercury's polar regions (corresponding to ice deposits 0.05-60 m thick), Halley-type comets can supply (0.2-20) x 10(16) g of water to the poles (0.07-7 m of ice), and asteroids can provide (0.4-20) x 10(16) g of water to the poles (0.1-8 m of ice). Although all these external sources are nominally sufficient to explain the estimated amount of ice currently at Mercury's poles, impacts by a few large comets and/or asteroids seem to provide the best explanation for both the amount and cleanliness of the ice deposits on Mercury. Despite their low population estimates in the inner solar system, Jupiter-family comets are particularly promising candidates for delivering water to Mercury because they have a larger volatile content than asteroids and more favorable orbital and impact characteristics than Halley-type comets. (C) 1999 Academic Press. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Moses, JI (reprint author), Lunar & Planetary Inst, 3600 Bay Area Blvd, Houston, TX 77058 USA. EM moses@lpi3.jsc.nasa.gov RI Moses, Julianne/I-2151-2013 OI Moses, Julianne/0000-0002-8837-0035 NR 59 TC 37 Z9 37 U1 0 U2 3 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 1999 VL 137 IS 2 BP 197 EP 221 DI 10.1006/icar.1998.6036 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 182TV UT WOS:000079515000001 ER PT J AU Benner, LAM Ostro, SJ Rosema, KD Giorgini, JD Choate, D Jurgens, RE Rose, R Slade, MA Thomas, ML Winkler, R Yeomans, DK AF Benner, LAM Ostro, SJ Rosema, KD Giorgini, JD Choate, D Jurgens, RE Rose, R Slade, MA Thomas, ML Winkler, R Yeomans, DK TI Radar observations of asteroid 7822 (1991 CS) SO ICARUS LA English DT Article DE asteroids; radar; 1991 CS ID IMAGES; 1620-GEOGRAPHOS; SHAPE AB We report Doppler-only (cw) radar observations of near-Earth asteroid 1991 CS obtained at Goldstone at a transmitter frequency of 8510 MHz (3.5 cm) on 1996 August 26, 27, 28, and 29. Weighted, optimally filtered sums of cw echoes achieve signal-to-noise ratios in excess of 300 per day and thoroughly cover the asteroid in rotation phase (synodic period = 2.39 h, obtained photometrically by P. Pravec et al. 1998, Icarus 136, 124-153). A weighted sum of all cw spectra gives an OC radar cross section of 0.24 +/- 0.08 km(2) and a circular polarization ratio of 0.28 +/- 0.001. Our observations place up to 50 0,98-Hz resolution cells on 1991 CS at echo powers greater than 2 standard deviations of the noise. Variations of similar to 10 Hz in the echo's 2-sigma bandwidth are evident on each day and are consistent with the rotation period. Inversion of echo edge frequencies yields convex bulls of the pole-on silhouette for each day. The hulls have a mean elongation and rms dispersion of 1.18 +/- 0.02 and place a lower bound on the maximum pole-on dimension of 1.3 km/cos delta, where d is the angle between the radar line-of-sight and the asteroid's apparent equator The hulls suggest that 1991 CS has the least elongated pole-on silhouette of any of the nine near-Earth asteroids for which similar shape information from radar observations is available. If we assume that the projected area of 1991 CS is the same as that of a sphere with a diameter of 1.1 km, equal to the lower bound on the minimum breadth of the pole-on silhouette on August 28 and 29, then 1991 CS's radar cross section and absolute magnitude of 17.5 correspond to upper limits on the radar and optical geometric albedos of 0.25 and 0.14 that are consistent with its S-class taxonomy. The circular polarization ratio and radar albedo do not vary substantially as a function of rotation phase, suggesting that the near-surface of 1991 CS is relatively uniform. Among the 20 S-dass asteroid radar detections previously reported, the circular polarization ratio of 1991 CS is greater than 11, comparable to 4, and less than 5. (C) 1999 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Benner, LAM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 38 TC 7 Z9 7 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 1999 VL 137 IS 2 BP 247 EP 259 DI 10.1006/icar.1999.6044 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 182TV UT WOS:000079515000004 ER PT J AU Roos-Serote, M Drossart, P Encrenaz, T Carlson, RW Leader, F AF Roos-Serote, M Drossart, P Encrenaz, T Carlson, RW Leader, F TI Constraints on the tropospheric cloud structure of Jupiter from spectroscopy in the 5-mu m region: A comparison between Voyager/lRIS, Galileo/NIMS, and ISO/SWS spectra SO ICARUS LA English DT Article DE Jupiter; atmosphere; infrared observations; hot spots; water cloud ID NORTH EQUATORIAL BELT; GAS-COMPOSITION; ABSORPTION-SPECTRA; WATER-VAPOR; IRIS DATA; ABUNDANCE; SPECTROMETER; ATMOSPHERE; PAIRS; CH3D AB The 5-mu m window in the spectrum of Jupiter is one of the few regions that gives access to the vertical structure of the troposphere between pressure levels of approximately 4 and 8 bar, Voyager/IRIS spectra obtained in 1979 during the Voyager flybys have been analyzed intensively over the past two decades. Most of these analyses concluded on a vertical cloud structure consisting of three layers: an ammonia cloud layer with a base around 0.5 bar, an ammonium-hydrosulfide layer at about 2 bar, and a water cloud layer with a base somewhere between 5 and 7 bar. However, the recent Galileo entry probe measurements of the vertical atmospheric structure in a hot spot region show a quite different picture. The data indicate only two cloud layers, at about 0.7 bar and 1.34 bar, and no significant cloud opacity between 2 and 22 bar, where the Probe measurements ended. New data from the Galileo/NIMS and ISO/SWS experiments agree with the Probe findings. The inclusion of cloud opacity between 5 and 7 bar in the model atmosphere results in a poor fit to the NIMS and ISO data. A comparison between Voyager/IRIS spectra and the ISO/SWS and Galileo/NIMS spectra shows a slope in the continuum level of the IRIS spectra for wavelengths shorter than 5 mu m, not present in either SWS spectrum or the NIMS spectra, We show that to fit the IRIS spectra, an additional opacity somewhere between 3 and 8 bar is needed in the model atmosphere. We suggest that, most likely, a calibration problem occurred with the Voyager/IRIS data in this spectral region, even though temporal variations in the deep atmospheric structure of Jupiter cannot be ruled out altogether. (C) 1999 Academic Press. C1 Lisbon Astron Observ, P-1300 Lisbon, Portugal. Observ Paris Meudon, DESPA, F-92195 Meudon, France. Jet Prop Lab, Pasadena, CA 91109 USA. RP Roos-Serote, M (reprint author), Lisbon Astron Observ, Tapada da Ajuda, P-1300 Lisbon, Portugal. NR 32 TC 18 Z9 18 U1 1 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 1999 VL 137 IS 2 BP 315 EP 340 DI 10.1006/icar.1998.6043 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 182TV UT WOS:000079515000008 ER PT J AU Cox, CB Coney, TA AF Cox, CB Coney, TA TI Advanced communications technology satellite (ACTS) fade compensation protocol impact on very small-aperture terminal bit error rate performance SO IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS LA English DT Article DE adaptive coding; attenuation; propagation; rain; satellite communication; satellites AB The Advanced Communications Technology Satellite (ACTS) communications system operates at Ka band. ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of an analysis characterizing the improvement in VSAT performance provided by this protocol. The metric for performance is VSAT bit error rate (BER) availability. The acceptable availability defined by communication system design specifications is 99.5% for a BER of 5E-7 or better. VSAT EER availabilities with and without rain fade compensation are presented. A comparison shows the improvement in EER availability realized with rain fade compensation. Results are presented for an eight-month period and for 24 months spread over a three-year period. The two time periods represent two different configurations of the fade compensation protocol. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Analex Corp, Brook Pk, OH 44142 USA. RP Cox, CB (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 5 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0733-8716 J9 IEEE J SEL AREA COMM JI IEEE J. Sel. Areas Commun. PD FEB PY 1999 VL 17 IS 2 BP 173 EP 179 DI 10.1109/49.748781 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 173WC UT WOS:000079001900006 ER PT J AU Acosta, RJ Bauer, R Krawczyk, RJ Reinhart, RC Zernic, MJ Gargione, F AF Acosta, RJ Bauer, R Krawczyk, RJ Reinhart, RC Zernic, MJ Gargione, F TI Advanced Communications Technology Satellite (ACTS): Four-year system performance SO IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS LA English DT Article AB The Advanced Communications Technology Satellite (ACTS) was conceived at the National Aeronautics and Space Administration (NASA) in the late 1970's as a follow-on program to ATS and CTS to continue NASA's long history of satellite communications projects. The ACTS project set the stage for the C-band satellites that started the industry, and later the ACTS project established the use of Ku-band for video distribution and direct-to-home broadcasting. ACTS, launched in September 1993 from the space shuttle, created a revolution in satellite system architecture by using digital communications techniques employing key technologies such as a fast hopping multibeam antenna, an on-board baseband processor, a wide-band microwave switch matrix, adaptive rain fade compensation, and the use of 900 MHz transponders operating at Ka-band frequencies. This paper describes the lessons learned in each of the key ACTS technology areas, as well as in the propagation investigations. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Lockheed Martin Missles & Space, Newtown, PA 18940 USA. RP Acosta, RJ (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 21 TC 9 Z9 9 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0733-8716 J9 IEEE J SEL AREA COMM JI IEEE J. Sel. Areas Commun. PD FEB PY 1999 VL 17 IS 2 BP 193 EP 203 DI 10.1109/49.748783 PG 11 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 173WC UT WOS:000079001900008 ER PT J AU Deutsch, L AF Deutsch, L TI A discordant note SO IEEE SPECTRUM LA English DT Letter C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Deutsch, L (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9235 J9 IEEE SPECTRUM JI IEEE Spectr. PD FEB PY 1999 VL 36 IS 2 BP 8 EP 8 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA 160ZZ UT WOS:000078264400008 ER PT J AU Park, SJ Dill, DL AF Park, SJ Dill, DL TI An executable specification and verifier for relaxed memory order SO IEEE TRANSACTIONS ON COMPUTERS LA English DT Article DE multiprocessors; memory models; formal method; executable specification; automatic verification AB The Mur phi description language and verification system for finite-state concurrent systems is applied to the problem of specifying a family of multiprocessor memory models described in the SPARC Version 9 architecture manual. The description language allows for a straightforward operational description of the memory model which can be used as a specification for programmers and machine architects. The automatic verifier can be used to generate all possible outcomes of small assembly language multiprocessor programs in a given memory model, which is very helpful for understanding the subtleties of the model. The verifier can also check the correctness of assembly language programs including synchronization routines. This paper describes the memory models and their encoding in the Mur phi description language. We describe how synchronization routines can be verified and how finite stale programs can be analyzed. We also present some interesting findings from the verification and the analysis. C1 NASA, RIACS, Ames Res Ctr, Moffett Field, CA 94035 USA. Stanford Univ, Dept Comp Sci, Stanford, CA 94305 USA. RP Park, SJ (reprint author), NASA, RIACS, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 22 TC 14 Z9 14 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 0018-9340 J9 IEEE T COMPUT JI IEEE Trans. Comput. PD FEB PY 1999 VL 48 IS 2 BP 227 EP 235 DI 10.1109/12.752664 PG 9 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 174WV UT WOS:000079060200015 ER PT J AU Ponchak, GE Matloubian, M Katehi, LPB AF Ponchak, GE Matloubian, M Katehi, LPB TI A measurement-based design equation for the attenuation of MMIC-compatible coplanar waveguides SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE attenuation; coplanar waveguide; microwave transmission lines ID LINES AB Measured attenuation of coplanar waveguide (CPW) transmission lines with narrow strip and slot widths fabricated on GaAs, high-resistivity Si, and InP is used to derive a new closed-form equation to calculate line losses. This new equation is shown to be more accurate than previous expressions, yet simple enough to be programmed into a hand-held calculator since it is based on a simple relationship between attenuation and the product of the strip and slot widths. The derived equation is applicable to CPW's with aspect ratio and metal thicknesses commonly used in monolithic microwave integrated circuits. C1 NASA, Lewis Res Ctr, Electron Device Technol Branch, Cleveland, OH 44135 USA. Hughes Res Labs, Malibu, CA 90265 USA. Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. RP Ponchak, GE (reprint author), NASA, Lewis Res Ctr, Electron Device Technol Branch, Cleveland, OH 44135 USA. NR 12 TC 23 Z9 23 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD FEB PY 1999 VL 47 IS 2 BP 241 EP 243 DI 10.1109/22.744301 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA 166CX UT WOS:000078559600016 ER PT J AU Barbier, LM Birsa, F Odom, J Barthelmy, SD Gehrels, N Krizmanic, JF Palmer, D Parsons, AM Stahle, CM Tueller, J AF Barbier, LM Birsa, F Odom, J Barthelmy, SD Gehrels, N Krizmanic, JF Palmer, D Parsons, AM Stahle, CM Tueller, J TI XA readout chip characteristics and CdZnTe spectral measurements SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article DE CdZnTe; strip detector ASIC; XA ID DETECTORS; SEMICONDUCTOR; SPECTROSCOPY AB The authors report on the performance of a CdZnTe (CZT) array readout by an Xi (X-ray imaging chip produced at the AMS foundry) application specific readout chip (ASIC). The array was designed and fabricated at NASA/Goddard Space Flight Center (GSFC) as a prototype for the Burst Are-Second Imaging and Spectroscopy gamma-rag instrument. The XA ASIC was obtained from Integrated Detector and Electronics (IDE), in Norway, Performance characteristics and spectral data for Am-241 are presented both at room temperature and at -20 degrees C. The measured noise (sigma) was 2.5 keV at 60 keV at room temperature, This paper represents a progress report on work with the XA ASIC and CZT detectors, Work is continuing and in particular, larger arrays are planned for future NASA missions. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Greenbelt, MD 20771 USA. Orbital Sci Corp, Greenbelt, MD 20771 USA. RP Barbier, LM (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Gehrels, Neil/D-2971-2012; Tueller, Jack/D-5334-2012; Barthelmy, Scott/D-2943-2012; Parsons, Ann/I-6604-2012 NR 14 TC 12 Z9 12 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD FEB PY 1999 VL 46 IS 1 BP 7 EP 18 DI 10.1109/23.747762 PG 12 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 169VP UT WOS:000078770000002 ER PT J AU Bose, D Govindan, TR Meyyappan, M AF Bose, D Govindan, TR Meyyappan, M TI A self-consistent fluid simulation of an inductively coupled plasma reactor SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article DE inductively coupled plasma; gas flow; plasma reactor design; reactor model; two-dimensional model AB We have developed a self consistent fluid model that couples plasma dynamics, Navier-Stokes equations, and Maxwell's equations to analyze inductively coupled plasma reactors used in semiconductor processing, Two dimensional simulations of an N-2 plasma have been performed and found to agree well with experimental data, Images of plasma density, gas and ion traces are provided. C1 ELORET Thermosci Inst, Palo Alto, CA 94303 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bose, D (reprint author), ELORET Thermosci Inst, Palo Alto, CA 94303 USA. NR 6 TC 2 Z9 2 U1 1 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD FEB PY 1999 VL 27 IS 1 BP 54 EP 55 DI 10.1109/27.763031 PG 2 WC Physics, Fluids & Plasmas SC Physics GA 197MX UT WOS:000080369700026 ER PT J AU Johnson, AE Kang, SB AF Johnson, AE Kang, SB TI Registration and integration of textured 3D data SO IMAGE AND VISION COMPUTING LA English DT Article; Proceedings Paper CT International Conference on Recent Advances in 3-D Digital Imaging and Modeling CY MAY 12-15, 1997 CL OTTAWA, CANADA SP Natl Res Council Canada, Int Assoc Pattern Recognit DE scene modeling; 3D registration; volumetric integration; omnidirectional stereo; textured 3D data ID REPRESENTATION; STEREO AB In general, multiple views are required to create a complete 3D model of an object or of a multi-roomed indoor scene. In this work, we address the problem of merging multiple textured 3D data sets, each of which corresponds to a different view of a scene. There are two steps to the merging process: registration and integration. To register, or align, data sets we use a modified version of the iterative closest point (ICP) algorithm; our version, which we call color ICP, considers not only 3D information, but color as well. We show that the use of color decreases registration error significantly when using omnidirectional stereo data sets. Once the 3D data sets have been registered, we integrate them to produce a seamless, composite 3D textured model. Our approach to integration uses a 3D occupancy grid to represent likelihood of spatial occupancy through voting. In addition to occupancy information, we store surface normal in each voxel of the occupancy grid. Surface normal is used to robustly extract a surface from the occupancy grid; on that surface we blend textures from multiple views. (C) 1999 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Digital Equipment Corp, Cambridge Res Lab, Cambridge, England. RP CALTECH, Jet Prop Lab, Mail Stop 107-102,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM aej@robotics.jpl.nasa.gov NR 28 TC 55 Z9 64 U1 2 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0262-8856 EI 1872-8138 J9 IMAGE VISION COMPUT JI Image Vis. Comput. PD FEB PY 1999 VL 17 IS 2 BP 135 EP 147 DI 10.1016/S0262-8856(98)00117-6 PG 13 WC Computer Science, Artificial Intelligence; Computer Science, Software Engineering; Computer Science, Theory & Methods; Engineering, Electrical & Electronic; Optics SC Computer Science; Engineering; Optics GA 174ZD UT WOS:000079065700006 ER PT J AU Newman, JC Phillips, EP Swain, MH AF Newman, JC Phillips, EP Swain, MH TI Fatigue-life prediction methodology using small-crack theory SO INTERNATIONAL JOURNAL OF FATIGUE LA English DT Article DE crack closure; fatigue; fracture; large cracks; plasticity; small cracks; spectrum loading ID GROWTH AB This paper reviews the capabilities of a plasticity induced crack-closure model to predict fatigue lives of metallic materials using 'small-crack theory' for various materials and loading conditions. Crack-tip constraint factors, to account for three-dimensional State-of-stress effects, were selected to correlate large-crack growth rare data as a function of the effective-stress-intensity factor range (Delta K-eff) under constant-amplitude loading. Some modifications to the Delta K-eff rate relations were needed in the near-threshold regime to fit measured small-crack growth rate behavior and fatigue endurance limits. The model was then used to calculate small- and large-crack growth rates, and to predict total fatigue lives, for notched and un-notched specimens made of two aluminum alloys and a steel under constant-amplitude and spectrum loading. Fatigue lives were calculated using the crack-growth relations and microstructural features like those that initiated cracks for the aluminum alloys and steel for edge-notched specimens. An equivalent-initial-flaw-size concept was used to calculate fatigue lives in other cases. Results from the tests and analyses agreed well. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. Lockheed Martin Engn & Sci, Hampton, VA 23665 USA. RP Newman, JC (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 39 TC 121 Z9 126 U1 3 U2 35 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0142-1123 J9 INT J FATIGUE JI Int. J. Fatigue PD FEB PY 1999 VL 21 IS 2 BP 109 EP 119 DI 10.1016/S0142-1123(98)00058-9 PG 11 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 161KX UT WOS:000078288800001 ER PT J AU Garg, VK Rigby, DL AF Garg, VK Rigby, DL TI Heat transfer on a film-cooled blade - effect of hole physics SO INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW LA English DT Article DE film-cooling; turbine blade; hole physics ID TURBINE-BLADES; LEADING-EDGE; TEMPERATURE AB A multiblock, three-dimensional Navier-Stokes code has been used to study the within-hole and near-hole physics in relation to heat transfer on a film-cooled blade. The flow domain consists of the coolant how through the plenum and hole-pipes for the three staggered rows of shower-head holes on the VKI rotor, and the main Row over the blade. A multiblock grid is generated that is nearly orthogonal to the various surfaces, It may be noted that for the VKI rotor the shower-head holes are inclined at 30 degrees to the spanwise direction, and are normal to the streamwise direction on the blade. Wilcox's k-omega turbulence model is used. The present study provides a much better comparison for the span-averaged heat transfer coefficient on the blade surface with the experimental data than an earlier analysis wherein coolant velocity and temperature distributions were specified at the hole exits rather than extending the computational domain into the hole-pipe and plenum. Details of the distributions of coolant velocity, temperature, ii and omega at the hole exits are also presented. (C) 1999 Elsevier Science Inc. All rights reserved. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NASA, Lewis Res Ctr, Brookpark, OH 44142 USA. RP Garg, VK (reprint author), NASA, Lewis Res Ctr, 21000 Brookpk Rd,Mail Stop 5-11, Cleveland, OH 44135 USA. NR 44 TC 24 Z9 32 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0142-727X J9 INT J HEAT FLUID FL JI Int. J. Heat Fluid Flow PD FEB PY 1999 VL 20 IS 1 BP 10 EP 25 DI 10.1016/S0142-727X(98)10048-6 PG 16 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA 164WF UT WOS:000078486000002 ER PT J AU Hunt, LR Meyer, G Ramakrishna, V AF Hunt, LR Meyer, G Ramakrishna, V TI Guidance and stable and unstable manifolds with input SO INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL LA English DT Article DE stable inversion; stable and unstable manifolds; steady state; guidance; deconvolution ID NONLINEAR-SYSTEMS; OUTPUT TRACKING; INVERSION AB The theory in this paper is motivated by the problem of aircraft guidance in automatic flight control, in which plant models are nonlinear. This leads us to consider the stable inversion problem, which in turn can be cast as the problem of finding a bounded solution of a time-varying nonlinear system subject to a bounded input. Under the appropriate assumptions there is a unique bounded (for all time) continuous solution to this time-varying nonlinear system in response to the bounded (for all time) input. We show that there is a (local) stable manifold containing-all bounded continuous solutions for non-negative time, and that all such solutions converge to the aforementioned unique solution as time: goes to infinity. Likewise there is a (local) unstable manifold containing all bounded solutions for non-positive time and these converge to the unique solution as time goes to minus infinity. In fact, the unique solution (cross the time axis) is the intersection of the stable and unstable manifolds. (C) 1999 John Wiley & Sons, Ltd. C1 Univ Texas, Ctr Engn Math, Richardson, TX 75083 USA. Univ Texas, Program Elect Engn EC 33, Richardson, TX 75083 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Texas, Program Math Sci EC35, Richardson, TX 75083 USA. RP Hunt, LR (reprint author), Univ Texas, Ctr Engn Math, POB 830688, Richardson, TX 75083 USA. EM hunt@utdallas.edu NR 15 TC 3 Z9 3 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 1049-8923 J9 INT J ROBUST NONLIN JI Int. J. Robust Nonlinear Control PD FEB PY 1999 VL 9 IS 2 BP 85 EP 99 DI 10.1002/(SICI)1099-1239(199902)9:2<85::AID-RNC394>3.0.CO;2-R PG 15 WC Automation & Control Systems; Engineering, Electrical & Electronic; Mathematics, Applied SC Automation & Control Systems; Engineering; Mathematics GA 171KW UT WOS:000078863700002 ER PT J AU Shen, B Yang, K Zang, L Chen, ZZ Zhou, YG Chen, P Zhang, R Huang, ZC Zhou, HS Zheng, YD AF Shen, B Yang, K Zang, L Chen, ZZ Zhou, YG Chen, P Zhang, R Huang, ZC Zhou, HS Zheng, YD TI Study of photocurrent properties of GaN ultraviolet photoconductor grown on 6H-SiC substrate SO JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS LA English DT Article DE GaN; ultraviolet detector; photocurrent; responsivity; response time ID PHOTODETECTOR AB The properties of a photoconductive ultraviolet detector based on a GaN epilayer grown on a 6H-SiC substrate using metal-organic chemical Vapor deposition were investigated. We obtained the detectable energy span of the device up to the ultraviolet region by photocurrent measurement. The spectral responsivity remained nearly constant for wavelengths ranging from 250 to 365 nm and dropped by three orders of magnitude within 15 nm of the band edge from 365 nm to 380 nm. The detector was measured to have a responsivity of 133 A/W at a wavelength of 360 nm under a 5 V bias, and the voltage-dependent responsivity was evatuated. Furthermore, a convenient method to determine the response time was developed. The relationship between response time and bias was obtained. C1 Nanjing Univ, Dept Phys, Nanjing 210093, Peoples R China. Nanjing Univ, Solid State Microstruct Lab, Nanjing 210093, Peoples R China. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Electrotech Lab, Div Energy Technol, Tsukuba, Ibaraki, Japan. RP Shen, B (reprint author), Nanjing Univ, Dept Phys, Nanjing 210093, Peoples R China. NR 11 TC 15 Z9 15 U1 1 U2 9 PU JAPAN J APPLIED PHYSICS PI MINATO-KU TOKYO PA DAINI TOYOKAIJI BLDG 24-8 SHINBASHI 4-CHOME, MINATO-KU TOKYO, 105, JAPAN SN 0021-4922 J9 JPN J APPL PHYS 1 JI Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. PD FEB PY 1999 VL 38 IS 2A BP 767 EP 769 DI 10.1143/JJAP.38.767 PG 3 WC Physics, Applied SC Physics GA 182BC UT WOS:000079477800030 ER PT J AU Burke, PJ Schoelkopf, RJ Prober, DE Skalare, A Karasik, BS Gaidis, MC McGrath, WR Bumble, B LeDuc, HG AF Burke, PJ Schoelkopf, RJ Prober, DE Skalare, A Karasik, BS Gaidis, MC McGrath, WR Bumble, B LeDuc, HG TI Mixing and noise in diffusion and phonon cooled superconducting hot-electron bolometers SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID ELECTROMAGNETIC-RADIATION; NBN DETECTOR; 2.5 THZ; MIXER; GHZ; WAVELENGTHS; BANDWIDTH AB We report a systematic, comprehensive set of measurements on the dynamics and noise processes in diffusion and phonon-cooled superconducting hot-electron bolometer mixers which will serve as ultralow noise detectors in THz heterodyne receivers. The conversion efficiency and output noise of devices of varying lengths were measured with radio frequency between 8 and 40 GHz. The devices studied consist of 100-Angstrom-thin film Nb bridges connected to thick (1000 Angstrom), high conductivity normal metal (Au) leads. The lengths of the devices studied range from 0.08 to 3 mm. For devices longer than the electron-phonon interaction length Le-ph = root D tau(e-ph), with D the diffusion constant and tau(e-ph)(-1) the electron-phonon interaction rate, the hot electrons are cooled dominantly by the electron-phonon interaction, which in Nb is too slow for practical applications. If the device length is less than pi Le-ph (approximate to 1 mu m at 4.2 K), then out diffusion of heat into the high conductivity leads dominates the cooling process. In this limit, the intermediate frequency (IF) bandwidth is found to vary as L-2, with L the bridge length, as expected for diffusion cooling. The shortest device has an IF bandwidth greater than 6 GHz, the largest reported for a low-T-c superconducting bolometric mixer. The dominant component of the output noise decreases with frequency in the same manner as the conversion efficiency, consistent with a model based on thermal fluctuations. The noise bandwidth is larger than the gain bandwidth, and the mixer noise is low, ranging from 100 to 530 K (double sideband). The crossover from phonon dominated to diffusion dominated behavior is also demonstrated using noise thermometry measurements in the normal state. Scalar measurements of the device differential impedance in the intermediate state agree with a theoretical model which takes into account the thermal and electrical dynamics. We also present detailed comparisons with theoretical predictions of the output noise and conversion efficiency. (C) 1999 American Institute of Physics. [S0021-8979(99)08602-8]. C1 Yale Univ, Dept Phys, New Haven, CT 06520 USA. CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RP Burke, PJ (reprint author), CALTECH, MS114-36 Condensed Matter Phys, Pasadena, CA 91125 USA. RI Schoelkopf, Robert/J-8178-2012; Gaidis, Michael/D-3327-2013; Burke, Peter/F-3308-2010; Karasik, Boris/C-5918-2011 NR 46 TC 40 Z9 41 U1 0 U2 5 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD FEB 1 PY 1999 VL 85 IS 3 BP 1644 EP 1653 DI 10.1063/1.369299 PG 10 WC Physics, Applied SC Physics GA 158VB UT WOS:000078137100052 ER PT J AU Srinivasan, RS Gerth, WA Powell, MR AF Srinivasan, RS Gerth, WA Powell, MR TI Mathematical models of diffusion-limited gas bubble dynamics in tissue SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE decompression sickness; perfusion; boundary layer ID DECOMPRESSION-SICKNESS AB Mathematical models of bubble evolution in tissue have recently been incorporated into risk functions for predicting the incidence of decompression sickness (DCS) in human subjects after diving and/or flying exposures. Bubble dynamics models suitable for these applications assume the bubble to be either contained in an unstirred tissue (two-region model) or surrounded by a boundary layer within a well-stirred tissue (three-region model). The contrasting premises regarding the bubble-tissue system lead to different expressions for bubble dynamics described in terms of ordinary differential equations. However, the expressions are shown to be structurally similar with differences only in the definitions of certain parameters that can be transformed to make the models equivalent at large tissue volumes. It is also shown that the tao-region model is applicable only to bubble evolution in tissues of infinite extent and cannot be readily applied to bubble evolution in finite tissue volumes to simulate how such evolution is influenced by interactions among multiple bubbles in a given tissue. Tao-region models that are incorrectly applied in such cases yield results that may be reinterpreted in terms of their three-region model equivalents but only if the parameters in the two-region model transform into consistent values in the three-region model. Then such transforms field inconsistent parameter values for the three-region model, results may be qualitatively correct but are in substantial quantitative error. Obviation of these errors through appropriate use of the different models may improve performance of probabilistic models of DCS occurrence that express DCS risk in tel ms of simulated in vivo gas and bubble dynamics. C1 Wyle Labs, Houston, TX 77058 USA. Duke Univ, Med Ctr, Dept Anesthesiol, Durham, NC 27710 USA. NASA, Lyndon B Johnson Space Ctr, Environm Physiol Lab, Houston, TX 77058 USA. RP Srinivasan, RS (reprint author), Wyle Labs, 1290 Hercules Dr,Suite 120, Houston, TX 77058 USA. NR 18 TC 35 Z9 35 U1 1 U2 4 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD FEB PY 1999 VL 86 IS 2 BP 732 EP 741 PG 10 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 191EQ UT WOS:000080009800043 PM 9931215 ER PT J AU Freilich, MH Qi, HB Dunbar, RS AF Freilich, MH Qi, HB Dunbar, RS TI Scatterometer beam balancing using open-ocean backscatter measurements SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID SPACEBORNE SCATTEROMETERS; ERS-1 SATELLITE; CALIBRATION; ASSIMILATION AB Calculation of vector winds from spaceborne fan-beam scatterometers requires that backscatter measurements from different antennas be relatively calibrated to high accuracy. A method is developed to perform postlaunch antenna calibration using global mean ocean backscatter measurements in conjunction with estimates of the statistical distribution of near-surface wind velocity and the model function relating backscatter to winds. Substantial analytic simplifications result from assuming that the wind speed and azimuth distributions are separable and that the upwind-downwind asymmetry term in the model function is small. The analytic model allows quantitative examination of the sensitivity of the technique to errors in the approximate wind distributions and empirical model function. The approach and its assumptions are tested using 13 months of ERS-1 backscatter data, surface wind estimates from two operational weather analyses, and three empirical C-band model functions. It is shown that the ERS-1 antennas are relatively calibrated to within 0.2 dB, which is consistent with other published results obtained using ground receiving stations and Amazon forest data. The results are nearly insensitive to realistic errors in the estimated wind velocity distributions and model function. Analysis suggests that the ocean antenna calibration technique should be accurate to about 0.2 dB using as little as 3 weeks of scatterometer data. C1 Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Freilich, MH (reprint author), Oregon State Univ, Coll Ocean & Atmospher Sci, 104 Ocean Adm Bldg, Corvallis, OR 97331 USA. EM mhf@oce.orst.edu NR 20 TC 9 Z9 11 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD FEB PY 1999 VL 16 IS 2 BP 283 EP 297 DI 10.1175/1520-0426(1999)016<0283:SBBUOO>2.0.CO;2 PG 15 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 168GJ UT WOS:000078683100009 ER PT J AU Buonsanto, MJ Gonzalez, SA Pi, X Ruohoniemi, JM Sulzer, MP Swartz, WE Thayer, JP Yuan, DN AF Buonsanto, MJ Gonzalez, SA Pi, X Ruohoniemi, JM Sulzer, MP Swartz, WE Thayer, JP Yuan, DN TI Radar chain study of the May, 1995 storm SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article ID TRAVELING IONOSPHERIC DISTURBANCES; TOTAL ELECTRON-CONTENT; F-REGION; GEOMAGNETIC STORMS; MAGNETIC STORM; LATITUDE; FIELDS; MODEL; CIRCULATION; DYNAMICS AB We summarize the main features of the ionospheric F region as observed by the Sondrestrom, Millstone Hill, Arecibo, and Jicamarca incoherent scatter radars during the 1-5 May, 1995 CEDAR Storm Study interval. This paper apparently represents the first study of a major storm interval using the current incoherent scatter radar chain supported by the U.S. National Science Foundation. We focus most attention on 2-3 May, and include additional data from IMP-8, the St. John's magnetometer, SuperDARN, and global total electron content (TEC) maps from GPS. Three intervals of likely penetration of magnetospheric electric field from high to low latitude are identified on 2 May. A unique feature of this storm are the strong daytime equatorward wind surges in the neutral meridional wind observed at Millstone Hill. The first of these (at 14 UT on 2 May) is apparently due to a travelling atmospheric disturbance launched by intense frictional and Joule heating as observed at Sondrestrom. An evening enhancement in NmF(2) (the 'dusk effect') is typically seen only on the first day of a geomagnetic storm. However, during this storm a strong dusk effect is seen at Millstone Hill on 2, 3, and 4 May, associated with the equatorward wind surges. A penetrating eastward electric field also contributed to the dusk effect on 2 May. A large rise in hmF(2) at Arecibo near 0000 UT on 3 May is due to the same eastward electric field, which penetrates to the equator, causing a strong upward plasma drift at Jicamarca. This apparently results in a poleward expansion of the equatorial anomaly zones as seen in GPS total electron content, and an increase in NmF(2) at Arecibo to the largest value seen at midnight in several years. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 MIT, Haystack Observ, Westford, MA 01886 USA. Arecibo Observ, Arecibo, PR 00613 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. Cornell Univ, Sch Elect Engn, Ithaca, NY 14853 USA. SRI Int, Ctr Geosci & Engn, Menlo Park, CA 94025 USA. RP Buonsanto, MJ (reprint author), MIT, Haystack Observ, Westford, MA 01886 USA. RI Gonzalez, Sixto/G-1982-2011; THAYER, JEFFREY P./B-7264-2016 OI Gonzalez, Sixto/0000-0001-5544-1426; THAYER, JEFFREY P./0000-0001-7127-8251 NR 35 TC 24 Z9 24 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD FEB PY 1999 VL 61 IS 3-4 BP 233 EP 248 DI 10.1016/S1364-6826(98)00134-5 PG 16 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 181UQ UT WOS:000079461200006 ER PT J AU Bounoua, L Collatz, GJ Sellers, PJ Randall, DA Dazlich, DA Los, SO Berry, JA Fung, I Tucker, CJ Field, CB Jensen, TG AF Bounoua, L Collatz, GJ Sellers, PJ Randall, DA Dazlich, DA Los, SO Berry, JA Fung, I Tucker, CJ Field, CB Jensen, TG TI Interactions between vegetation and climate: Radiative and physiological effects of doubled atmospheric CO2 SO JOURNAL OF CLIMATE LA English DT Article ID GENERAL-CIRCULATION MODEL; SURFACE PARAMETERIZATION SIB2; ICE-CLOUD MICROPHYSICS; TERRESTRIAL CARBON METABOLISM; GLOBAL CLIMATE; STOMATAL CONDUCTANCE; TRANSIENT-RESPONSE; BOUNDARY-LAYER; PHOTOSYNTHESIS; SIMULATIONS AB The radiative and physiological effects of doubled atmospheric carbon dioxide (CO2) on climate are investigated using a coupled biosphere-atmosphere model. Five 30-yr climate simulations, designed to assess the radiative and physiological effects of doubled CO2, were compared to a 30-yr control run. When the CO2 concentration was doubled for the vegetation physiological calculations only assuming no changes in vegetation biochemistry, the mean temperature increase over land was rather small (0.3 K) and was associated with a slight decrease in precipitation (-0.3%). In a second case, the vegetation was assumed to have adapted its biochemistry to a doubled CO2 (2 x CO2) atmosphere and this down regulation caused a 35% decrease in stomatal conductance and a 0.7-K increase in land surface temperature. The response of the terrestrial biosphere to radiative forcing alone-that is, a conventional greenhouse warming effect-revealed important interactions between the climate and the vegetation. Although the global mean photosynthesis exhibited no change, a slight stimulation was observed in the tropical regions, whereas in the northern latitudes photosynthesis and canopy conductance decreased as a result of high temperature stress during the growing season. This was associated with a temperature increase of more than 2 K greater in the northern latitudes than in the Tropics (4.0 K vs 1.7 K). These interactions also resulted in an asymmetry in the diurnal temperature cycle, especially in the Tropics where the nighttime temperature increase due to radiative forcing was about twice that of the daytime, an effect not discernible in the daily mean temperatures. The radiative forcing resulted in a mean temperature increase over land of 2.6 K and 7% increase in precipitation with the least effect in the Tropics. As the physiological effects were imposed along with the radiative effects, the overall temperature increase over land was 2.7 K but with a smaller difference (0.7 K) between the northern latitudes and the Tropics. The radiative forcing resulted in an increase in available energy at the earth's surface and, in the absence of physiological effects, the evapotranspiration increased. However, changes in the physiological control of evapotranspiration due to increased CO2 largely compensated for the radiative effects and reduced the evapotranspiration approximately to its control value. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. NASA, JSC, Houston, TX USA. Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. Sci Syst & Applicat Inc, NASA, GSFC, Greenbelt, MD USA. Carnegie Inst Washington, Dept Plant Biol, Stanford, CA 94305 USA. Univ Victoria, Dept Earth & Ocean Sci, Victoria, BC, Canada. RP Bounoua, L (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. EM bounoua@dounia.gsfc.nasa.gov RI Randall, David/E-6113-2011; collatz, george/D-5381-2012; Los, Sietse/G-8985-2012; OI Randall, David/0000-0001-6935-4112; Los, Sietse/0000-0002-1325-3555 NR 51 TC 55 Z9 58 U1 1 U2 10 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD FEB PY 1999 VL 12 IS 2 BP 309 EP 324 DI 10.1175/1520-0442(1999)012<0309:IBVACR>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 174LY UT WOS:000079037700001 ER PT J AU Russell, GL Rind, D AF Russell, GL Rind, D TI Response to CO2 transient increase in the GISS coupled model: Regional coolings in a warming climate SO JOURNAL OF CLIMATE LA English DT Article ID OCEAN-ATMOSPHERE MODEL; SEA-SURFACE TEMPERATURE; MEAN RESPONSE; ICE; VARIABILITY; AOGCM AB The GISS coupled atmosphere-ocean model is used to investigate the effect of increased atmospheric CO2 by comparing a compounded 1% CO2 increase experiment with a control simulation. After 70 yr of integration, the global surface air temperature in the 1% CO2 experiment is 1.43 degrees C warmer. In spite of this global warming, there are two distinct regions, the northern Atlantic Ocean and the southern Pacific Ocean, where the surface air temperature is up to 4 degrees C cooler. This situation is maintained by two positive feedbacks: a local effect on convection in the South Pacific and a nonlocal impact on the meridional circulation in the North Atlantic. The poleward transport of latent energy and dry static energy by the atmosphere is greater in the 1% CO2 experiment, caused by warming and therefore increased water vapor and greater greenhouse capacity at lower latitudes. The larger atmospheric transports tend to reduce upward vertical fluxes of heat and moisture from the ocean surface at high latitudes, which has the effect of stabilizing the ocean, reducing both convection and the thermohaline circulation. With less convection, less warm water is brought up from below, and with a reduced North Atlantic thermohaline circulation (by 30% at time of CO2 doubling), the poleward energy transport by the oceans decreases. The colder water then leads to further reductions in evaporation, decreases of salinity at high latitudes, continued stabilization of the ocean, and maintenance of reduced convection and meridional overturning. Although sea ice decreases globally, it increases in the cooling regions, which reduces the overall climate sensitivity, especially in the Southern Hemisphere. Tropical warming has been observed over the past several decades; if modeling studies such as this and others that have produced similar effects are valid, these processes may already be beginning. C1 NASA, Goddard Inst Space Studies, Goddard Space Flight Ctr, New York, NY 10025 USA. RP Russell, GL (reprint author), NASA, Goddard Inst Space Studies, Goddard Space Flight Ctr, 2880 Broadway, New York, NY 10025 USA. NR 29 TC 54 Z9 58 U1 3 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD FEB PY 1999 VL 12 IS 2 BP 531 EP 539 DI 10.1175/1520-0442(1999)012<0531:RTCTII>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 174LY UT WOS:000079037700015 ER PT J AU Pines, V Chait, A Zlatkowski, M Beckermann, C AF Pines, V Chait, A Zlatkowski, M Beckermann, C TI Equiaxed dendritic solidification in supercooled melts SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE dendrite; morphological instability; solidification; equiaxe ID SOLUTE DIFFUSION-MODEL; GROWTH AB The growth of equiaxed dendrites from a pure supercooled melt is examined. We propose modifications to the classical Ivantsov theory that allow for consideration of multiple interacting dendrites. The modified theory reveals the existence of a steady-state dendritic solidification mode in a frame of reference moving with the dendrite tip. This regime should be valid from the onset of nucleation to the commencement of time-dependent coarsening when the mass of the solid becomes comparable to the liquid mass in the solidification chamber. This regime is characterized by a reduced (relative to the single dendrite case) heat flux leading to slower solidification rates, but with the same level of supercooling. We study the effects of the relative proximity and number of interacting dendrites through a numerical example of solidification of succinonitrile, a common material used in many experiments. The data show that the model predicts a new steady growth regime that is different than the steady growth law of a single dendrite as described by Ivantsov theory. (C) 1999 Published by Elsevier Science B.V. All rights reserved. C1 NASA, Lewis Res Ctr, Computat Micrograv Lab, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Phys, Cleveland, OH 44106 USA. Univ Iowa, Dept Mech Engn, Iowa City, IA 52242 USA. RP Chait, A (reprint author), NASA, Lewis Res Ctr, Computat Micrograv Lab, Cleveland, OH 44135 USA. RI Beckermann, Christoph/F-7158-2010 OI Beckermann, Christoph/0000-0002-9976-0995 NR 15 TC 4 Z9 4 U1 0 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 FEB PY 1999 VL 197 IS 1-2 BP 355 EP 363 DI 10.1016/S0022-0248(98)00901-4 PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 162PG UT WOS:000078355300048 ER PT J AU Wilson, RM Hathaway, DH AF Wilson, RM Hathaway, DH TI Comment on "The predicted size of cycle 23 based on the inferred three-cycle quasiperiodicity of the planetary index Ap" SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Editorial Material ID SUNSPOT CYCLE-23; SOLAR-ACTIVITY; SOLAR-CYCLE-23; FORECAST C1 NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Wilson, RM (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. NR 19 TC 10 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD FEB 1 PY 1999 VL 104 IS A2 BP 2555 EP 2558 DI 10.1029/1998JA900074 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 170TX UT WOS:000078823900021 ER PT J AU Stowe, RP Sams, CF Mehta, SK Kaur, I Jones, ML Feeback, DL Pierson, DL AF Stowe, RP Sams, CF Mehta, SK Kaur, I Jones, ML Feeback, DL Pierson, DL TI Leukocyte subsets and neutrophil function after short-term spaceflight SO JOURNAL OF LEUKOCYTE BIOLOGY LA English DT Article DE microgravity; stress; chemotaxis; adhesion molecules ID LYMPHOCYTE SUBSETS; PERIPHERAL-BLOOD; SPACE-FLIGHT; EPINEPHRINE; STRESS; EXERCISE; MECHANISMS; HUMANS; MOBILIZATION; HORMONES AB Changes in leukocyte subpopulations and function after spaceflight have been observed but the mechanisms underlying these changes are not well defined. This study investigated the effects of short-term spaceflight (8-15 days) on circulating leukocyte subsets, stress hormones, immunoglobulin levels, and neutrophil function. At landing, a 1.5-fold increase in neutrophils was observed compared with preflight values; lymphocytes were slightly decreased, whereas the results were variable for monocytes. No significant changes were observed in plasma levels of immunoglobulins, cortisol, or adrenocorticotropic hormone. In contrast, urinary epinephrine, norepinephrine, and cortisol were significantly elevated at landing. Band neutrophils were observed in 9 of 16 astronauts. Neutrophil chemotactic assays showed a 10-fold decrease in the optimal dose response after landing. Neutrophil adhesion to endothelial cells was increased both before and after spaceflight. At landing, the expression of MAC-1 was significantly decreased while L-selectin Tvas significantly increased. These functional alterations may be of clinical significance on long-duration space missions. C1 NASA, Life Sci Res Labs, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Texas, Med Branch, Dept Pathol, Galveston, TX 77550 USA. Enterprise Advisory Serv Inc, Houston, TX USA. Cintein LLC, Union, KY USA. RP Pierson, DL (reprint author), NASA, Life Sci Res Labs, Lyndon B Johnson Space Ctr, Mail Code SD3, Houston, TX 77058 USA. NR 40 TC 73 Z9 81 U1 0 U2 4 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0741-5400 J9 J LEUKOCYTE BIOL JI J. Leukoc. Biol. PD FEB PY 1999 VL 65 IS 2 BP 179 EP 186 PG 8 WC Cell Biology; Hematology; Immunology SC Cell Biology; Hematology; Immunology GA 163EM UT WOS:000078390200005 PM 10088600 ER PT J AU Muldashev, TZ Lyapustin, AI Sultangazin, UM AF Muldashev, TZ Lyapustin, AI Sultangazin, UM TI Spherical harmonics method in the problem of radiative transfer in the atmosphere-surface system SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article AB A collection function method designed for calculating the angular dependence of radiance is described. It allows one to corrects the solution of the spherical harmonics method so that the single scattering contribution is calculated exactly regardless of the order of approximation PN As a consequence, a smoothed intensity of high accuracy is obtained at a lower N compared to other smoothing methods, which results in the decrease of computational time. Besides, the new method by itself is at least twice as fast as the conventional method of the source function integration. Based on the new method of smoothing, we found an empirical formula to predict the minimal order of the spherical harmonics method necessary to provide the accuracy of radiance calculations at the level of 0.2-0.3% for any given scattering function, except for extremely asymmetric ones. The use of this formula makes calculations automatical as it frees the user from the tedious procedure of trial and error while looking for the appropriate order of approximation in each specific case. (C) 1998 Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. Space Res Inst, Alma Ata, Kazakhstan. RP Lyapustin, AI (reprint author), NASA, Goddard Space Flight Ctr, USRA, Mailcode 920, Greenbelt, MD 20771 USA. RI Lyapustin, Alexei/H-9924-2014 OI Lyapustin, Alexei/0000-0003-1105-5739 NR 11 TC 22 Z9 22 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD FEB PY 1999 VL 61 IS 3 BP 393 EP 404 DI 10.1016/S0022-4073(98)00025-9 PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 158TY UT WOS:000078134000012 ER PT J AU Jacobson, N Farmer, S Moore, A Sayir, H AF Jacobson, N Farmer, S Moore, A Sayir, H TI High-temperature oxidation of boron nitride: I, monolithic boron nitride SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID STABILITY; KINETICS AB High-temperature oxidation of monolithic boron nitride (BN) is examined at 900-1200 degrees C. Hot-pressed BN and both low- and high-density chemically vapor-deposited BN are studied. The oxidation product is B2O3(I) and the oxidation kinetics are sensitive to crystallographic orientation, porosity, and impurity levels. The B2O3 product also reacts readily with ambient water vapor in the test furnace (ppm levels) to form the volatile species HBO2(g), leading to overall paralinear kinetics. The linear rate constant extracted from these experiments agreed with that predicted from diffusion of HBO2(g) across a static boundary layer. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Adv Ceram Corp, Lakewood, OH 44107 USA. RP Jacobson, N (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RI Jacobson, Nathan/A-9411-2009 NR 25 TC 80 Z9 82 U1 0 U2 19 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD FEB PY 1999 VL 82 IS 2 BP 393 EP 398 PG 6 WC Materials Science, Ceramics SC Materials Science GA 167VH UT WOS:000078654100018 ER PT J AU Waliser, DE Lau, KM Kim, JH AF Waliser, DE Lau, KM Kim, JH TI The influence of coupled sea surface temperatures on the Madden-Julian oscillation: A model perturbation experiment SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID OUTGOING LONGWAVE RADIATION; 40-50 DAY OSCILLATION; TROPICAL WESTERN PACIFIC; EVAPORATION-WIND FEEDBACK; PLANETARY-SCALE CIRCULATIONS; EASTERN EQUATORIAL PACIFIC; AUSTRALIAN SUMMER MONSOON; INTRASEASONAL TIME SCALES; CUMULUS CLOUD ENSEMBLE; 30-60 DAY OSCILLATIONS AB In this study, the authors compare the Madden-Julian oscillation (MJO) variability in the Goddard Laboratory for Atmospheres atmospheric general circulation model for two different sea surface temperature (SST) boundary conditions. In the "control" simulation, the model employs specified annual cycle SSTs. In the "coupled" simulation, the model employs the same annual cycle SSTs but in addition is coupled to a slab ocean mixed layer that provides prognostic SST anomalies equatorward of 24 degrees. The results show that the simplified interactive SST facilitates a better simulation with respect to a number of general model shortcomings associated with the MJO that were recently documented by Slingo et al. in an Atmospheric Model Intercomparison Project study. These improvements include 1) increased variability associated with the MJO, 2) a tendency for the timescales of the modeled intraseasonal variability to more closely match and consolidate around the timescales found in the observations, 3) a reduced eastward phase speed in the Eastern Hemisphere, and 4) an increased seasonal signature in the MJO with relatively more events occurring in the December-May period. The above changes are associated with a systematic change in SST, with warming of about 0.10 degrees-0.15 degrees C before the passage of the MJO convection center and cooling of the same magnitude after its passage, both of which appear to be roughly consistent with observations. These changes in SST are primarily due to decreased latent heat Bur (similar to 25 W m(-2)) and slightly enhanced surface shortwave flux (similar to 10 W m(-2)) to the east of the convection, enhanced latent heat flux and diminished shortwave flux (similar to 25 W m(-2)) coincident with the convection: and enhanced latent heat flux (-25 W m(-2)) just west of the convection. The results indicate that the enhanced SST to the east of the convection reinforces the meridional convergence associated with the frictional wave-CISK (conditional instability of the second kind) mechanism that appears to be at work within the model. This enhanced meridional convergence transports more low-level moisture into the region lying just east of convection. The resulting increase in moist static energy helps destabilize the disturbance and/or maintain it against dissipation more effectively relative to the case without SST coupling. The above results are discussed in terms of their relation to current MJO theory, as well as to their implications for medium- to extended-range weather forecasting. C1 SUNY Stony Brook, Inst Terr & Planetary Atmospheres, Stony Brook, NY 11794 USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Space Applicat Corp, Vienna, Austria. RP Waliser, DE (reprint author), SUNY Stony Brook, Inst Terr & Planetary Atmospheres, Stony Brook, NY 11794 USA. EM waliser@terra.msrc.sunysb.edu RI Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 98 TC 246 Z9 262 U1 1 U2 11 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD FEB 1 PY 1999 VL 56 IS 3 BP 333 EP 358 DI 10.1175/1520-0469(1999)056<0333:TIOCSS>2.0.CO;2 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 174RX UT WOS:000079049700001 ER PT J AU Smart, MC Ratnakumar, BV Surampudi, S AF Smart, MC Ratnakumar, BV Surampudi, S TI Electrolytes for low-temperature lithium batteries based on ternary mixtures of aliphatic carbonates SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID CARBONACEOUS MATERIALS; ION BATTERIES; ELECTRODES; INSERTION; ETHER; CELLS AB The low-temperature performance of lithium-ion cells in mainly limited by the electrolyte solution, which not only determines the ionic mobility between electrodes but also strongly affects the nature of surface films formed on the carbonaceous anode. The surface films provide kinetic stability to the electrode (toward electrolyte) and permit charge (electron) transfer across them, which in turn determine the cycle life and rate capability of lithium-ion cells. Aiming at enhancing low-temperature cell performance, we have studied electrolyte solutions based on different ratios of alkyl carbonate solvent mixtures, i.e., ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC), in terms of electrolyte conductivity, film resistance, film stability, and kinetics of lithium intercalation and deintercalation, at various temperatures. Electrolytes based on the ternary mixtures of EC, DEC, and DMC emerged a preferred combination compared to the binary analogues both in terms of conductivity and surface film characteristics, especially at low temperatures. These studies are further corroborated in sealed AA cells, which showed a synergistic effect of high durability from the DMC-based solutions and improved low-temperature performance from the DEC-based electrolytes. (C) 1999 The Electrochemical Society. S0013-4651(98)06-021-2. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Smart, MC (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM ratnakumar.V.bugga@jpl.nasa.gov NR 20 TC 125 Z9 137 U1 4 U2 41 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 65 SOUTH MAIN STREET, PENNINGTON, NJ 08534 USA SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD FEB PY 1999 VL 146 IS 2 BP 486 EP 492 DI 10.1149/1.1391633 PG 7 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA 171LZ UT WOS:000078866400012 ER PT J AU Johnson, SW Eiler, JH AF Johnson, SW Eiler, JH TI Fate of radio-tagged trawl web on an Alaskan beach SO MARINE POLLUTION BULLETIN LA English DT Article ID MARINE DEBRIS AB Thirty-five fragments of trawl web were radio-tagged on Kayak Island, Alaska, to determine their fate once stranded ashore, Tagged fragments placed in the immediate study area were monitored daily by a remote tracking station (RTS) from August 1994 to May 1995, Ground and aerial surveys in June 1995 located fragments that had moved out of the reception range of the RTS, Of the 35 tagged fragments, 18 (51%) remained on Kayak Island, whereas the whereabouts of 17 (49%) fragments were undetermined. Most fragments not relocated were lost during severe fall storms. Tagged fragments that remained on Kayak Island moved an average of 2.0 km from their original tagging location. Fragments not relocated were smaller ((x) over bar = 1.25 kg) than those found ((x) over bar = 6.28 kg), Missing fragments were likely washed back to sea. To reduce entanglement hazards to marine life, stranded trawl web should be removed from beaches during clean-ups to prevent possible reentry into the ocean. (C) 1999 Published by Elsevier Science Ltd. All rights reserved. C1 Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, Juneau, AK 99801 USA. RP Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, 11305 Glacer Highway, Juneau, AK 99801 USA. NR 14 TC 3 Z9 3 U1 2 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0025-326X EI 1879-3363 J9 MAR POLLUT BULL JI Mar. Pollut. Bull. PD FEB PY 1999 VL 38 IS 2 BP 136 EP 141 DI 10.1016/S0025-326X(98)00109-X PG 6 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 172NN UT WOS:000078930800019 ER PT J AU MacKay, DDS Charnley, SB AF MacKay, DDS Charnley, SB TI The silicon chemistry of IRC+10 degrees 216 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE molecular processes; circumstellar matter; stars : individual : IRC+10 degrees 216; stars : late-type ID IRC + 10216; RESOLVED ATOMIC RESONANCE; DENSE INTERSTELLAR CLOUDS; CARBON-CHAIN MOLECULES; ABSORPTION-SPECTROSCOPY; RATE CONSTANTS; CIRCUMSTELLAR ENVELOPE; NEUTRAL REACTIONS; IRC+10216; SIC2 AB We have modelled the circumstellar chemistry of SiC, SiC2, SiC4, SiH2, SiH4, HNSi and SiN in the carbon-rich envelope of the variable star IRC + 10 degrees 216. We find, in agreement with previous work, that SiC2 must be a parent and that neutral-neutral reactions are necessary to form SiC4. Our inclusion of many more neutral-neutral reactions has a limited influence on the calculated distributions of the Si-C compounds. In particular, the suggestion of Lucas et al. - that the SiC2 distribution peaks by almost an order of magnitude in the outer envelope relative to its inner envelope abundance - cannot be explained in any of our models. This enhancement is most likely to arise from a density peak or peaks along the line of sight. We show that the presence of SiH2 and the Si-N chemistry require that SiH4 supplies the bulk of available silicon in the photochemical region. The column densities and radial distributions of all the observed Si species are compared with their observed values, and column densities are given for several molecules predicted to be detectable in IRC + 10 degrees 216 - Sill, SiH3, SiC2H, HCSi, HNSi and SiC3. C1 Univ Kent, Elect Engn Labs, Unit Space Sci & Astrophys, Canterbury CT2 7NT, Kent, England. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. NASA, Div Space Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. RP MacKay, DDS (reprint author), Univ Kent, Elect Engn Labs, Unit Space Sci & Astrophys, Canterbury CT2 7NT, Kent, England. RI Charnley, Steven/C-9538-2012 NR 57 TC 35 Z9 36 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD FEB 1 PY 1999 VL 302 IS 4 BP 793 EP 800 DI 10.1046/j.1365-8711.1999.02175.x PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 169TZ UT WOS:000078765800022 ER PT J AU Chen, C Bishop, C AF Chen, C Bishop, C TI Comments on "Numerical simulations of an observed narrow cold-frontal rainband" Reply SO MONTHLY WEATHER REVIEW LA English DT Letter ID DYNAMICS; MODEL C1 NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Atmospheres Lab, Greenbelt, MD 20771 USA. Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA. RP Chen, C (reprint author), NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Atmospheres Lab, Code 912, Greenbelt, MD 20771 USA. NR 12 TC 2 Z9 2 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD FEB PY 1999 VL 127 IS 2 BP 258 EP 263 DI 10.1175/1520-0493(1999)127<0258:R>2.0.CO;2 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 174QT UT WOS:000079046700009 ER PT J AU Juday, RD Barton, RS Monroe, SE AF Juday, RD Barton, RS Monroe, SE TI Experimental optical results with minimum Euclidean distance optimal filters, coupled modulators, and quadratic metrics SO OPTICAL ENGINEERING LA English DT Article DE optical correlation pattern recognition; spatial light modulators; optical information processing ID SPATIAL LIGHT-MODULATOR; PATTERN-RECOGNITION; TARGET; NOISE; PHASE; LOCATION AB Optical correlators used in pattern recognition should have their operation optimized according to physically measurable behavior related to the correlator's task. The optimization is best done with explicit consideration of the limited set of complex values available to the filter. We earlier developed a theoretical filter computing strategy, MEDOF (minimum Euclidean distance optimal filter), that optimizes a wide variety of correlation metrics on physically realistic modulators. We use a single reference image and add noise according to a stated model. We show laboratory results for filters optimizing a variety of metrics on a highly coupled SLM. The results show improvements in the metrics by using MEDOF when compared with some other filter computing strategies such as matching phase. Optimizing SNR appears preferable to the other metrics when detecting an object in clutter of known power spectral density. (C) 1999 Society of Photo-Optical instrumentation Engineers. [S0091-3286(99)01802-4]. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Space Mission Syst & Serv, Houston, TX 77058 USA. RP Juday, RD (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code ER5, Houston, TX 77058 USA. NR 24 TC 10 Z9 10 U1 0 U2 0 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD FEB PY 1999 VL 38 IS 2 BP 302 EP 312 DI 10.1117/1.602089 PG 11 WC Optics SC Optics GA 165DV UT WOS:000078505200015 ER PT J AU Sicard, M Spyak, PR Brogniez, G Legrand, M Abuhassan, NK Pietras, C Buis, JP AF Sicard, M Spyak, PR Brogniez, G Legrand, M Abuhassan, NK Pietras, C Buis, JP TI Thermal-infrared field radiometer for vicarious cross-calibration: characterization and comparisons with other field instruments SO OPTICAL ENGINEERING LA English DT Article DE thermal-infrared radiometer; field measurements; validation; remote sensing AB A four-band (8.2 to 9.2, 10.5 to 11.5, 11.5 to 12.5, and 8 to 14 mu m), prototype, thermal-IR radiometer, model CE 312 [CE 312 is the company model number. In previous papers, the CE 312 was called the CLIMAT (conveyable low-noise IR radiometer for measurements of atmosphere and ground-surface targets)], with a built-in radiance reference is been fabricated by CIMEL Electronique (Paris, France) for use as a field instrument, The instrument is briefly described, laboratory characterization is detailed, and its field measurements are compared with those from three other radiometers. The CE 312's main characteristics are linearity of better than 0.8%, field of view of 9.5 deg; noise-equivalent temperature difference of 0.06 to 0.2 K (depending on the band) for brightness temperatures of 0 to 75 degrees C; SNR greater than 1100 for the broadband and greater than 400 for the other bands for brightness temperatures between 10 and 80 degrees C; and repeatability of the measured radiance smaller than 0.35% after four field campaigns, corresponding to 0.2 K in terms of brightness temperature. Field measurements were conducted over different periods during 1996 at Jornada Experimental Range, New Mexico, Lunar Lake and Railroad Valley, Nevada, and Lake Tahoe, California. The CE 312 compares quite favorably with the other instruments: the brightness temperature at two different sites compared to within 0.3 K with two instruments. These measurements show that the CE 312 thermal-IR radiometer is very stable for ambient temperatures varying between 15 and 60 degrees C and that the availability of several filters in the thermal-IR region can help tremendously to improve the accuracy of the radiance determination. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)01902-9]. C1 Univ Arizona, Ctr Opt Sci, Remote Sensing Grp, Tucson, AZ 85721 USA. Univ Sci & Tech Lille Flandres Artois, Opt Atmospher Lab, F-59655 Villeneuve Dascq, France. NASA, Goddard Space Flight Ctr, SSAI, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, GSC, Greenbelt, MD 20771 USA. CIMEL Elect, F-75011 Paris, France. RP Sicard, M (reprint author), Univ Paris 06, Serv Aeron, 4 Pl Jussieu,Tour 15,Et 5,C 102, F-75252 Paris 05, France. RI Sicard, Michael/K-9064-2013 OI Sicard, Michael/0000-0001-8287-9693 NR 22 TC 29 Z9 29 U1 0 U2 2 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD FEB PY 1999 VL 38 IS 2 BP 345 EP 356 DI 10.1117/1.602094 PG 12 WC Optics SC Optics GA 165DV UT WOS:000078505200020 ER PT J AU Cockell, CS Rothschild, LJ AF Cockell, CS Rothschild, LJ TI The effects of UV radiation A and B on diurnal variation in photosynthesis in three taxonomically and ecologically diverse microbial mats SO PHOTOCHEMISTRY AND PHOTOBIOLOGY LA English DT Article ID ULTRAVIOLET-RADIATION; OZONE DEPLETION; OXYGENIC PHOTOSYNTHESIS; SOLAR-RADIATION; CARBON FIXATION; MARINE DIATOM; PHYTOPLANKTON; CYANOBACTERIA; GROWTH; INHIBITION AB Photosynthetic primary production, the basis of most global food chains, is inhibited by UV radiation, Evaluating UV inhibition is therefore important for assessing the role of natural levels of UV radiation in regulating ecosystem behavior as well as the potential impact of stratospheric ozone depletion on global ecosystems, As both photosynthesis and UV fluxes :are subject to diurnal variations, we examined the diurnal variability of the effect of UV radiation on photosynthesis in three diverse algal mats, In one of the mats (Cyanidium caldarium) a small mean decrease in primary productivity over the whole day occurred when both UVA and UVB were screened out. In two of the mats (Lyngbya aestuarii and Zygogonium sp,) we found a mean increase in the total primary productivity over the day when UVB alone was screened and a further increase when UVA and UVB were both screened out. Variations in the effects of UV radiation were found at different times of the day. This diurnal variability may be because even under the same solar radiation flux, there are different factors that may control photosynthetic rate, including nutritional status and other physiological processes ill the cell. The results show the importance of assessing the complete diurnal productivity. For some of the time points the increase in the mean was still within the standard deviations in primary productivity, illustrating the difficulty in dissecting UV effects from other natural variations. C1 NASA, Ames Res Ctr, Ecosyst Sci & Technol Branch, Moffett Field, CA 94035 USA. RP Cockell, CS (reprint author), Carnegie Inst, 260 Panama St, Stanford, CA 94305 USA. NR 51 TC 20 Z9 20 U1 1 U2 4 PU AMER SOC PHOTOBIOLOGY PI AUGUSTA PA BIOTECH PARK, 1021 15TH ST, SUITE 9, AUGUSTA, GA 30901-3158 USA SN 0031-8655 J9 PHOTOCHEM PHOTOBIOL JI Photochem. Photobiol. PD FEB PY 1999 VL 69 IS 2 BP 203 EP 210 DI 10.1562/0031-8655(1999)069<0203:TEOURA>2.3.CO;2 PG 8 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA 168VQ UT WOS:000078714200016 PM 11536898 ER PT J AU Bryan, TC AF Bryan, TC TI Docking in space SO PHOTONICS SPECTRA LA English DT Letter C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Bryan, TC (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU LAURIN PUBL CO INC PI PITTSFIELD PA BERKSHIRE COMMON PO BOX 1146, PITTSFIELD, MA 01202 USA SN 0731-1230 J9 PHOTON SPECTRA JI Photon. Spect. PD FEB PY 1999 VL 33 IS 2 BP 12 EP 12 PG 1 WC Optics SC Optics GA 166NY UT WOS:000078584300003 ER PT J AU Greenwood, JB Smith, SJ Chutjian, A Pollack, E AF Greenwood, JB Smith, SJ Chutjian, A Pollack, E TI Experimental cross sections for electron excitation of the 2s (2)S -> 2p (2)P transition in C(3+) SO PHYSICAL REVIEW A LA English DT Article ID 2S-2P EXCITATION; ENERGY-LOSS; IMPACT; SPECTRUM AB Experimental cross sections are reported for electron excitation of the allowed 2s (2)S --> 2p (2)P transition in C(3-). Center-of-mass energies an from below threshold (7.00 eV). through threshold (8.00 eV), and up to approximately 1.5 times the threshold (12 eV). The present results an found to overlap earlier energy-loss data reported to energies of 8.45 eV. The data are also compared with other optical-emission results for this dipole-allowed transition and with several theoretical calculations. An ''electronic aperture'' is described that allows discrimination against elastically scattered electrons, with their larger Larmor radii, in experiments with magnetically confined ions or electrons. [S1050-2947(99) 10202-6]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Connecticut, Dept Phys, Storrs, CT 06269 USA. RP Greenwood, JB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Greenwood, Jason/L-4799-2014 NR 24 TC 21 Z9 21 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD FEB PY 1999 VL 59 IS 2 BP 1348 EP 1354 DI 10.1103/PhysRevA.59.1348 PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 169YW UT WOS:000078778500057 ER PT J AU Koumoutsakos, P AF Koumoutsakos, P TI Vorticity flux control for a turbulent channel flow SO PHYSICS OF FLUIDS LA English DT Letter ID BOUNDARY-LAYER; DRAG REDUCTION; WALL AB A feedback control algorithm using wall only information has been applied in simulations of low Reynolds number (Re-tau = 180) turbulent channel flow. The present control scheme is based on the manipulation of the vorticity flux components, which can be obtained as a function of time by measuring the instantaneous pressure at the wall and calculating its gradient. The strength of the unsteady mass transpiration actuators can be derived explicitly by inverting a system of equations whose terms depend on the relative locations of the sensors and actuators. The results of the simulations indicate a large (up to 40%) drag reduction. Moreover it appears that using the present methodology open-loop control laws can be devised. (C) 1999 American Institute of Physics. [S1070-6631(99)01701-8]. C1 ETH Zurich, Inst Fluiddynam, CH-8092 Zurich, Switzerland. NASA, Ames Res Ctr, Ctr Turbulence Res, Moffett Field, CA 94035 USA. RP Koumoutsakos, P (reprint author), ETH Zurich, Inst Fluiddynam, CH-8092 Zurich, Switzerland. EM petros@ifd.mavt.ethz.ch RI Koumoutsakos, Petros/A-2846-2008 OI Koumoutsakos, Petros/0000-0001-8337-2122 NR 15 TC 45 Z9 45 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD FEB PY 1999 VL 11 IS 2 BP 248 EP 250 DI 10.1063/1.869874 PG 3 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 159HR UT WOS:000078167000002 ER PT J AU Grasso, F Pirozzoli, S Gatski, TB AF Grasso, F Pirozzoli, S Gatski, TB TI Analysis and simulation of a turbulent, compressible starting vortex SO PHYSICS OF FLUIDS LA English DT Article ID FLOWS; MODELS; WAVE AB The numerical simulation of a shock induced, turbulent compressible vortex is analyzed. The vortex is generated by the movement of an (unsteady) shock over the trailing-edge of a two-dimensional airfoil at different incidence angle. A theoretical analysis is performed for the case of a turbulent line vortex, at a low (vortex) Mach number and high Reynolds number, as a basis of comparison for the dynamic structure of the starting vortex. This theoretical analysis confirms the existence of an equilibrium structure of the isolated vortex similar to the laminar case. In the numerical computations, both an isotropic eddy viscosity two-equation turbulence model and an algebraic stress model are employed to assess the influence of turbulence model on the predictive capabilities of such a how including the realization of the self-similar behavior found in the isolated vortex case The results are also compared to theoretical estimates of the production-to-dissipation rate ratio for both types of turbulence models, and to recent experiments on such flows, (C) 1999 American Institute of Physics. [S1070-6631(99)00202-0]. C1 Univ Rome La Sapienza, Dipartimento Meccan & Aeronaut, I-00184 Rome, Italy. NASA, Langley Res Ctr, Aerodynam & Acoust Methods Branch, Hampton, VA 23681 USA. RP Grasso, F (reprint author), Univ Rome La Sapienza, Dipartimento Meccan & Aeronaut, Via Eudossiana 18, I-00184 Rome, Italy. NR 26 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 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD FEB PY 1999 VL 11 IS 2 BP 356 EP 367 DI 10.1063/1.869885 PG 12 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 159HR UT WOS:000078167000013 ER PT J AU Wu, JZ Zhou, Y Fan, M AF Wu, JZ Zhou, Y Fan, M TI A note on kinetic energy, dissipation and enstrophy SO PHYSICS OF FLUIDS LA English DT Article ID VORTICITY DYNAMICS AB We show that the dissipation rate of a Newtonian fluid with constant shear viscosity has three constituents from dilatation, vorticity, and surface strain. The last one, being associated with the most complicated manners of fluid deformation, only contributes to the change of internal energy but not that of kinetic energy. The distinction of these dissipation constituents is used to identify typical compact flow structures at high Reynolds numbers, such as shock waves, thin vortex layers, and filaments. This identification is of particular interest in studying turbulence structures. We then cast the incompressible version of the simplified kinetic-energy transport equation to a novel form, which is free from the work rate done by surface stresses but in which the full dissipation reenters. This result is of relevance to the physical routes via which turbulent energy is transferred to small scales. (C) 1999 American Institute of Physics. [S1070-6631(99)01602-5]. C1 Univ Tennessee, Inst Space, Tullahoma, TN 37388 USA. IBM Corp, Div Res, Thomas J Watson Res Ctr, Yorktown Heights, NY 10598 USA. NASA, Inst Comp Applicat Sci & Engn, Langley Res Ctr, Hampton, VA 23681 USA. RP Wu, JZ (reprint author), Univ Tennessee, Inst Space, Tullahoma, TN 37388 USA. NR 11 TC 5 Z9 5 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD FEB PY 1999 VL 11 IS 2 BP 503 EP 505 DI 10.1063/1.869866 PG 3 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 159HR UT WOS:000078167000028 ER PT J AU Bildsten, L Strohmayer, T AF Bildsten, L Strohmayer, T TI New views of neutron stars SO PHYSICS TODAY LA English DT Article ID ACCRETING PULSARS; SPIN-DOWN; RAY; BINARY; SYSTEM C1 Univ Calif Berkeley, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. RP Bildsten, L (reprint author), Univ Calif Berkeley, Berkeley, CA 94720 USA. NR 32 TC 17 Z9 17 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD FEB PY 1999 VL 52 IS 2 BP 40 EP 46 DI 10.1063/1.882523 PG 7 WC Physics, Multidisciplinary SC Physics GA 162YW UT WOS:000078376100012 ER PT J AU Feibelman, WA AF Feibelman, WA TI Detection of O VII lambda 1522 in IUE spectra of planetary nebula nuclei and other hot stars SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID HUBBLE-SPACE-TELESCOPE; 2 HOT AB We present the first detection of O VII lambda 1522 emission or absorption from archival IUE spectra in 14 planetary nebula nuclei and three PG 1159-type stars. The n = 5 --> 6 transition of O VII was determined by Kruk & Werner and observed by them in the spectrum of the very hot PG 1159-type star H1504+65 from data obtained with the Hopkins Ultraviolet Telescope (HUT). Emission-line fluxes or absorption equivalent widths as well as radial velocities for the program stars are presented. The precise rest wavelength for the 5 --> 6 transition requires further investigation. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Feibelman, WA (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 35 TC 4 Z9 4 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD FEB PY 1999 VL 111 IS 756 BP 221 EP 226 DI 10.1086/316317 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 163PG UT WOS:000078413500009 ER PT J AU Shinn, JL Badhwar, GD Xapsos, MA Cucinotta, FA Wilson, JW AF Shinn, JL Badhwar, GD Xapsos, MA Cucinotta, FA Wilson, JW TI An analysis of energy deposition in a tissue equivalent proportional counter onboard the space shuttle SO RADIATION MEASUREMENTS LA English DT Article ID NUCLEAR FRAGMENTATION MODEL; GALACTIC COSMIC-RADIATION; TRANSPORT; SPECTRA; DISTRIBUTIONS; APPLICABILITY; FLUCTUATIONS; IONIZATION; EVENTS; SITES AB An improved prediction for space radiations in the lower earth orbits measured by the shuttle TEPC is obtained when energy loss straggling and chord length distribution of the detector are considered. A generalized analytic model is used to describe the energy deposition of direct ion interaction events in a micron-size detector. The transport calculation accounting for the shuttle configuration is accomplished by using a new version of HZETRN that has been extensively verified with laboratory and flight data. The agreement of predicted and measured lineal energy spectra is within 70% for the region above 2 keV/mu m but within a factor of 2.3 underpredicted for the region below this value. The inclusion of indirect delta ray events in the model is needed before possible causes for the underprediction below 2 keV/mu m can be assessed. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Div Mat, Hampton, VA 23681 USA. NASA, Lyndon B Johnson Space Ctr, Space Radiat Anal Grp, Houston, TX 77058 USA. USN, Res Lab, Washington, DC 20375 USA. RP Shinn, JL (reprint author), NASA, Langley Res Ctr, Div Mat, Hampton, VA 23681 USA. NR 42 TC 13 Z9 13 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1350-4487 J9 RADIAT MEAS JI Radiat. Meas. PD FEB PY 1999 VL 30 IS 1 BP 19 EP 28 DI 10.1016/S1350-4487(98)00085-7 PG 10 WC Nuclear Science & Technology SC Nuclear Science & Technology GA 180RN UT WOS:000079399100003 PM 11542667 ER PT J AU Goyal, SK Seyfried, MS O'Neill, PE AF Goyal, SK Seyfried, MS O'Neill, PE TI Correction of surface roughness and topographic effects on airborne SAR in mountainous rangeland areas SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SYNTHETIC-APERTURE RADAR; SOIL-MOISTURE ESTIMATION; BARE SOIL; SCATTERING MODEL; MICROWAVE; DEPENDENCE; IMAGERY; CLASSIFICATION; BACKSCATTER; CALIBRATION AB Synthetic aperture radar (SAR) has potential use as a means of measuring soil-water content from space or high altitude airborne platforms. However, the signal from other landscape features, such as topography, vegetation, and surface roughness, may overwhelm and confound the soil moisture signal. Previous researchers tried to correct for topographic effects using incident angle (theta) as the most significant landscape variable. Those corrections were not effective because of the poor correlation between the SAR backscatter coefficient (sigma(0)) and theta. This may be attributed to surface roughness, vegetation effects, or low resolution digital elevation data. In this article, we determined the effects of vegetation, surface roughness, and topography on sigma(0). By comparing the normalized difference vegetation index (NDVI) and the SAR-based vegetation index (SBVI), it was found that the sparse vegetation cover of sagebrush in the rangeland areas of the Reynolds Creek Experimental Watershed (RCEW) does not affect L band HH polarization SAR sigma(0). Root mean square (RMS) height of surface (h), determined using L band copolarized SAR sigma(0) in an empirical algorithm (Dubois et al., 1995), helped in stratifying the study area into low and high surface roughness areas. The high surface roughness areas, determined using the algorithm, were found to match with very rocky and extremely rocky areas, classified using detailed soil type information in a Geographic Information System (GIS). The performance of theta-based correction function improved significantly after incorporating h into the mode. (C) Elsevier Science Inc., 1999. C1 Idaho Dept Water Resources, Boise, ID 83706 USA. ARS, USDA, Boise, ID USA. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Goyal, SK (reprint author), Idaho Dept Water Resources, 1301 N Orchard St, Boise, ID 83706 USA. EM sgoyal@idwr.state.id.us RI O'Neill, Peggy/D-2904-2013 NR 42 TC 10 Z9 13 U1 3 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD FEB PY 1999 VL 67 IS 2 BP 124 EP 136 DI 10.1016/S0034-4257(98)00077-7 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 160XB UT WOS:000078256200001 ER PT J AU Abdalati, W Krabill, WB AF Abdalati, W Krabill, WB TI Calculation of ice velocities in the Jakobshavn Isbrae area using airborne laser altimetry SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SATELLITE RADAR INTERFEROMETRY; SHEET AB The ability to measure velocities of fast-moving glaciers is essential to the understanding and interpretation of their dynamics and related processes. This is especially important in the Jakobshavn drainage basin of the Greenland ice sheet, where a significant portion of the ice sheet mass loss occurs and the iceberg calving rate is high. In this article, zee present a method for using airborne laser altimetry data to determine surface velocities in portions of the Jakobshavn drainage basin that have distinct elevation features. By examining correlations between repeat elevation surveys, the motion of these features, the most distinct of which are crevasses, is tracked. Results show that for areas with a standard deviation in elevation in excess of 1 m, displacement of features can be tracked to a precision of 1-2 m, and the corresponding velocities can be retrieved. The maximum velocity of the Jakobshavn Isbrae, at its calving front, is found to be nearly 7 km yr(-1). Ice stream boundaries and flow patterns can also be observed in the derived velocity data. (C)Elsevier Science Inc., 1999. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20770 USA. NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Island, VA 23337 USA. RP Abdalati, W (reprint author), NASA, Goddard Space Flight Ctr, Code 971, Greenbelt, MD 20770 USA. EM abdalati@gsfc.nasa.gov NR 20 TC 29 Z9 30 U1 0 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD FEB PY 1999 VL 67 IS 2 BP 194 EP 204 DI 10.1016/S0034-4257(98)00086-8 PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 160XB UT WOS:000078256200006 ER PT J AU Deering, DW Eck, TF Banerjee, B AF Deering, DW Eck, TF Banerjee, B TI Characterization of the reflectance anisotropy of three boreal forest canopies in spring-summer SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID LEAF-AREA INDEX; ATMOSPHERE-BIOSPHERE EXCHANGE; BIDIRECTIONAL REFLECTANCE; CARBON-DIOXIDE; CONIFER FORESTS; HOT-SPOT; MODEL; VEGETATION; RADIATION; PHOTOSYNTHESIS AB As a part of the Boreal Ecosystem-Atmosphere Study (BOREAS), measurements of the spectral reflectance anisotropy of three boreal forest canopies were studied for cloudless sky conditions at the phenological growth stages which were at or near maximum leaf area index at each site. The three sites were relatively homogeneous mature stands of black spruce, jack pine, and aspen located in the southern boreal zone of central Saskatchewan. Measurements of the spectal bidirectional reflectance factors with a 15 degrees instrument field of view in three spectral bands centered at 662 nm, 826 nm, and 1658 nm were made with the PARABOLA instrument over a range of solar zenith angles typically varying from 35 degrees (near solar noon) to 70 degrees. The measured reflectance factors showed large anisotropy at all three sites and for all three wavelengths, with prominant backscatter peak reflectances, and strong retro solar view angle (hot spot) maximum reflectances in the visible (662 nm) and shortwave infrared (1658 nm) for the jack pine and black spruce sites, with a less pronounced hot spot at the aspen site. Pronounced effects of canopy and understory shadowing in the visible, as a function of solar zenith angle (SZA), were observed for the black spruce and jack pine sites, with resultant large linear increases in computed normalized difference and simple ratio vegetation indices as SZA increased for near-nadir view angles. Hemispheric spectral reflectances or spectral albedos were computed from angular integration of PARABOLA measured bidirectional reflectances. Visible (662 nm.) hemispheric reflectances for the jack pine and black spruce canopies showed very little variation with solar zenith angle, while near-infrared hemispheric reflectances increased strongly with increasing SW. Estimates were made of the total shortwave albedo for the aspen and jack pine sites from irradiance and reflectance weighting of the spectral hemispheric reflectances in the three measured wavelengths. Comparison of estimated to pyranometer measured total albedo showed all estimates to be biased high, but only by about 0.007-0.018, depending on which of two sets of pyranometer measured albedos were utilized for the comparison. The measured bidirectional reflectance factor (BRF) data sets reported in this study coupled with ancillary data of biophysical parameters collected at the same sites by BOREAS researchers provide a unique data set for the de development and characterization of canopy bidirectional reflectance modeling and for the interpretation of remotely sensed data for boreal forest canopies. (C)Elsevier Science Inc., 1999. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Raytheon STX Corp, Greenbelt, MD 20771 USA. RP Eck, TF (reprint author), NASA, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. RI ECK, THOMAS/D-7407-2012 NR 42 TC 71 Z9 77 U1 2 U2 14 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD FEB PY 1999 VL 67 IS 2 BP 205 EP 229 DI 10.1016/S0034-4257(98)00087-X PG 25 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 160XB UT WOS:000078256200007 ER PT J AU Peele, AG AF Peele, AG TI Investigation of etched silicon wafers for lobster-eye optics SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID X-RAY OPTICS; PORE MICROCHANNEL PLATES; N-TYPE SILICON; ARRAYS AB We investigate some high aspect ratio etched silicon to determine its suitability as a lobster-eye optic. The major defects present leading to performance degradation are identified and tolerance goals are set for prospective candidates. (C) 1999 American Institute of Physics. [S0034-6748(99)03002-6]. C1 NASA, Goddard Space Flight Ctr, NRC, Greenbelt, MD 20771 USA. RP Peele, AG (reprint author), NASA, Goddard Space Flight Ctr, NRC, Greenbelt, MD 20771 USA. EM peele@milkyway.gsfc.nasa.gov NR 24 TC 15 Z9 15 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD FEB PY 1999 VL 70 IS 2 BP 1268 EP 1273 DI 10.1063/1.1149584 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 164YD UT WOS:000078490400004 ER PT J AU Cushman, GM Gummer, RM Buchanan, E Jenkins, O Powers, T AF Cushman, GM Gummer, RM Buchanan, E Jenkins, O Powers, T TI Automated liquid helium transfer system SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB An optimized automated liquid helium transfer system diverts warm gas from entering the cryostat, saves on liquid helium consumption, reduces man hours, and enhances safety. Control electronics, cryogenic valves and a multipiped transfer line are also discussed. (C) 1999 American Institute of Physics. [S0034-6748(99)03502-9]. C1 NASA, Raytheon STX, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Precis Cryogen, Indianapolis, IN 46214 USA. RP Cushman, GM (reprint author), NASA, Raytheon STX, Goddard Space Flight Ctr, Code 685, Greenbelt, MD 20771 USA. NR 4 TC 1 Z9 1 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD FEB PY 1999 VL 70 IS 2 BP 1575 EP 1576 DI 10.1063/1.1149627 PG 2 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 164YD UT WOS:000078490400060 ER PT J AU Neugebauer, M AF Neugebauer, M TI The three-dimensional solar wind at solar activity minimum SO REVIEWS OF GEOPHYSICS LA English DT Article ID HELIOSPHERIC MAGNETIC-FIELD; HIGH HELIOGRAPHIC LATITUDES; CORONAL MASS EJECTIONS; ULYSSES OBSERVATIONS; FLUX TUBES; COSMIC-RAY; ACCELERATION; PLASMA; SLOW; HOLE AB In early 1998 the Ulysses spacecraft made history by completing an orbit around the Sun inclined to the solar equator by 80 degrees. It observed the properties of the high-latitude heliosphere at a time of low solar activity when the configuration of the solar magnetic field was relatively simple. The solar wind data acquired by Ulysses have placed firm observational constraints on theories of the acceleration of the fast wind from the polar regions. The speed of the polar solar wind was in the range 750-800 km s(-1), with a slow increase toward the poles. The polar proton flux of similar to 2 x 10(8) cm(-2) s(-1) was only two-thirds the low-latitude flux but still sufficiently high to require energy sources in addition to the conduction of heat from the hot solar corona. In comparison with the slow, low-latitude solar wind, the heavy ions in the fast, high-latitude wind had less elemental fractionation relative to the solar surface and a lower state of ionization. Fine structures in the polar solar wind, named microstreams, exhibited a correlation between speed, proton temperature, and alpha particle abundance. The absence of a latitude dependence of the widths of the microstreams suggests that they are caused by temporal, rather than purely spatial variations at the Sun. Magnetic field observations revealed a latitude-independent radial field strength of similar to 3 nT (normalized to 1 AU) and a large flux of outward propagating Alfven waves. The most probable direction of the interplanetary magnetic field was close to the Archimedes (Parker) spiral predicted on the basis of radial fields close to the Sun combined with the effects of solar rotation. The fluctuations about the average direction were so large, however, that there was little latitudinal variation of the average value of \B-R\/B, where B-R is the radial component of the field with magnitude B. Latitudinal transport of field lines and nonradial field directions near the Sun appear to be other necessary additions to the simple Parker model. Some unexpected differences were found between the low- and the high-latitude properties of the plasma from transient events called coronal mass ejections (CMEs). At high latitudes, the speeds of the CME plasma clouds were close to the speed of the ambient fast wind, shocks were observed both ahead of and behind the CMEs, and enhancements of the helium abundance and of high charge states of heavy ions were not observed, as they often are at low latitudes. The review closes with a summary of arguments in support of the view that the fast solar wind observed by Ulysses at intermediate latitudes has its origin at higher latitudes in the polar coronal holes. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Neugebauer, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 169-506, Pasadena, CA 91109 USA. EM mneugeb@jplsp.jpl.nasa.gov NR 68 TC 27 Z9 31 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 8755-1209 J9 REV GEOPHYS JI Rev. Geophys. PD FEB PY 1999 VL 37 IS 1 BP 107 EP 126 DI 10.1029/1998RG900001 PG 20 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 165RA UT WOS:000078534000003 ER PT J AU McClinton, CR AF McClinton, CR TI Air-breathing engines SO SCIENTIFIC AMERICAN LA English DT Article C1 NASA, Hyper X Program, Langley Res Ctr, Hampton, VA 23665 USA. RP McClinton, CR (reprint author), NASA, Hyper X Program, Langley Res Ctr, Hampton, VA 23665 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 USA SN 0036-8733 J9 SCI AM JI Sci.Am. PD FEB PY 1999 VL 280 IS 2 BP 84 EP 85 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 158WY UT WOS:000078141500029 ER PT J AU Harris, HM AF Harris, HM TI Light sails SO SCIENTIFIC AMERICAN LA English DT Article C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Harris, HM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 USA SN 0036-8733 J9 SCI AM JI Sci.Am. PD FEB PY 1999 VL 280 IS 2 BP 90 EP 91 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 158WY UT WOS:000078141500032 ER PT J AU Leifer, SD AF Leifer, SD TI Reaching for the stars SO SCIENTIFIC AMERICAN LA English DT Article C1 CALTECH, Jet Prop Lab, Adv Propuls Technol Grp, Pasadena, CA 91109 USA. RP Leifer, SD (reprint author), CALTECH, Jet Prop Lab, Adv Propuls Technol Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 USA SN 0036-8733 J9 SCI AM JI Sci.Am. PD FEB PY 1999 VL 280 IS 2 BP 94 EP 95 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 158WY UT WOS:000078141500034 ER PT J AU Minnetyan, L Chamis, CC AF Minnetyan, L Chamis, CC TI Progressive fracture of adhesively bonded composite structures SO THEORETICAL AND APPLIED FRACTURE MECHANICS LA English DT Article DE adhesive bond; composites; composite structures; damage; degradation; durability; fracture; laminates; simulation; stiffened panel; structural degradation ID PRESSURE AB Progressive damage and fracture of adhesively bonded graphite/epoxy composite structures are evaluated via computational simulation. Load induced damage in both the adhesive bond and the adjoining laminate is considered. An integrated computer code is used for the simulation of structural degradation under loading. Damage initiation, growth, accumulation, and propagation to fracture are included in the simulations. Results show in detail the damage progression sequence and structural fracture resistance during different degradation stages. Design implications with regard to damage tolerance of adhesively bonded joints are examined. Influence of the type of loading as well as adhesive thickness on damage initiation and progression for an adhesively bonded composite structure are investigated. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 NASA, Lewis Res Ctr, Res & Technol Directorate, Struct Div, Cleveland, OH 44135 USA. Clarkson Univ, Dept Civil & Environm Engn, Potsdam, NY 13699 USA. RP Chamis, CC (reprint author), NASA, Lewis Res Ctr, Res & Technol Directorate, Struct Div, Cleveland, OH 44135 USA. NR 10 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-8442 J9 THEOR APPL FRACT MEC JI Theor. Appl. Fract. Mech. PD FEB-MAR PY 1999 VL 31 IS 1 BP 75 EP 84 DI 10.1016/S0167-8442(98)00069-X PG 10 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 171XJ UT WOS:000078889400008 ER PT J AU Nutter, PA Manobianco, J AF Nutter, PA Manobianco, J TI Evaluation of the 29-km Eta model. Part I: Objective verification at three selected stations SO WEATHER AND FORECASTING LA English DT Article ID NATIONAL-WEATHER-SERVICE; ENVIRONMENTAL-PREDICTION; MESOSCALE MODEL; CENTERS; TEMPERATURE; FORECASTS; SURFACE; SCHEMES; SYSTEM; NCEP AB This paper describes an objective verification of the National Centers for Environmental Prediction 29-km Eta Model from May 1996 through January 1998. The evaluation was designed to assess the model's surface and upper-air point forecast accuracy at three selected locations during separate warm (May-August) and cool (October-January) season periods. In order to enhance sample sizes available for statistical calculations, the objective verification includes two consecutive warm and cool season periods. The statistical evaluation identified model biases that result from inadequate parameterization of physical processes. However, since the model biases are relatively small compared to the random error component, most of the total model error results from day-to-day variability in the forecasts and/or observations. To some extent, these nonsystematic errors reflect the variability in point observations that sample spatial and temporal scales of atmospheric phenomena that cannot be resolved by the model. On average, Meso Eta point forecasts provide useful guidance for predicting the evolution of the larger-scale environment. A more substantial challenge facing model users in real time is the discrimination of nonsystematic errors that tend to inflate the total forecast error. It is important that users maintain awareness of ongoing model updates because they modify the basic error characteristics.,particularly near the surface. While some of the changes in error were expected, others were not consistent with the intent of the model updates and further emphasize the need for ongoing sensitivity studies and localized statistical verification efforts. Objective verification of point forecasts is a stringent measure of model performance, but when used alone, is not enough to quantify the overall value that model guidance may add to the forecast process. Therefore, results from a subjective verification of the Meso Eta Model over the Florida peninsula are discussed in the companion paper by Manobianco and Nutter. C1 ENSCO Inc, Cocoa Beach, FL 32931 USA. NASA, Appl Meteorol Unit, Kennedy Space Ctr, FL USA. RP Manobianco, J (reprint author), ENSCO Inc, 1980 N Atlantic Ave,Suite 230, Cocoa Beach, FL 32931 USA. NR 32 TC 18 Z9 18 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0882-8156 J9 WEATHER FORECAST JI Weather Forecast. PD FEB PY 1999 VL 14 IS 1 BP 5 EP 17 DI 10.1175/1520-0434(1999)014<0005:EOTKEM>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 168JM UT WOS:000078688500001 ER PT J AU Manobianco, J Nutter, PA AF Manobianco, J Nutter, PA TI Evaluation of the 29-km Eta model. Part II: Subjective verification over Florida SO WEATHER AND FORECASTING LA English DT Article ID NATIONAL-WEATHER-SERVICE; ENVIRONMENTAL-PREDICTION; SOUTH FLORIDA; SEA BREEZES; CONVECTION; OPERATIONS; CENTERS; SYSTEM; SKILL; CAPE AB This paper describes a subjective evaluation of the National Centers for Environmental Prediction 29-km (Meso) Eta Model during the 1996 warm (May-August) and cool (October-January) seasons. The companion paper by Nutter and Manobianco presents results from an objective evaluation of the Meso Eta Model at three selected locations during the 1996 and 1997 warm and cool seasons. The overall evaluation is designed to assess the utility of the model for operational weather forecasting by the U.S. Air Force 45th Weather Squadron, National Weather Service (NWS) Spaceflight Meteorology Group, and NWS Office in Melbourne, Florida. In the subjective verification, limited case studies are used to highlight model capabilities and limitations in forecasting convective activity, the location and movement of cold fronts, and the onset of sea breezes over regions including east-central Florida. In addition, contingency tables and categorical scores are used to verify the occurrence of these phenomena throughout the season. Results from the subjective verification demonstrate that-model forecasts of developing weather events such as thunderstorms, sea breezes, and cold fronts are not always as accurate as might otherwise be implied by the seasonally averaged error statistics. Although the objective statistics do not indicate whether the model provides more accurate forecast guidance on average during either the warm or cool seasons, results from the subjective verification suggest that model forecasts over central Florida may be more useful during the cool season. This is because the Meso Eta Model resolution is not yet sufficient to resolve the small-scale details of sea and river/lake breeze circulations, thunderstorm outflow boundaries, and other phenomena, which play a dominant role in determining the short-term evolution of weather over east-central Florida during the warm season. Lessons learned from the subjective portion of the Meso Eta evaluation should apply equally as well to the recently upgraded "early" Eta Model running with a similar 32-km horizontal resolution. C1 ENSCO Inc, Cocoa Beach, FL 32931 USA. NASA, Appl Meteorol Unit, Kennedy Space Ctr, FL USA. RP Manobianco, J (reprint author), ENSCO Inc, 1980 N Atlantic Ave,Suite 230, Cocoa Beach, FL 32931 USA. NR 35 TC 13 Z9 13 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0882-8156 J9 WEATHER FORECAST JI Weather Forecast. PD FEB PY 1999 VL 14 IS 1 BP 18 EP 37 DI 10.1175/1520-0434(1999)014<0018:EOTKEM>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 168JM UT WOS:000078688500002 ER PT J AU Kaufman, GD Shinder, ME Perachio, AA AF Kaufman, GD Shinder, ME Perachio, AA TI Correlation of Fos expression and circling asymmetry during gerbil Vestibular compensation SO BRAIN RESEARCH LA English DT Article DE inducible transcription factor; antisense phosphorothioate oligonucleotides; prepositus hypoglossus; posture; movement; labyrinthectomy ID IN-VIVO; ANTISENSE OLIGONUCLEOTIDES; BRAIN-STEM; NEURONS; RAT; JUN; STIMULATION; STRIATUM; CELLS AB Vestibular compensation is a central nervous system process resulting in recovery of functional movement and control following a unilateral vestibular lesion. Small pressure injections of phosphorothioate 20mer oligonucleotides were used to probe the role of the Fos transcription protein during vestibular compensation in the gerbil brainstem. During isoflurane gas anesthesia, antisense probes against the c-fos mRNA sequence were injected into the medial vestibular and prepositus nuclei unilaterally prior to a unilateral surgical labyrinthectomy. Anionic dyes, which did not interact with the oligonucleotides, were used to mark the injection site and help determine the extent of diffusion. The antiFos oligonucleotide injections reduced Fos expression at the injection site in neurons which normally express Fos after the lesion, and alsb affected circling behavior induced by hemilabyrinthectomy. With both ipsilateral and contralateral medial vestibular and prepositus nuclei injections, less ipsilateral and more contralateral circling was noted in animals injected with antiFos injections as compared to non-injected controls. The degree of change in these behaviors was dependent upon the side of the injection. HistologicalIy, antiFos injections reduced the number of Fos immunolabeled neurons around the injection site, and increased Fos expression contralaterally. The correlation of the number of neurons with Fos expression to turning behavior was stronger for contralateral versus ipsilateral turns, and for neurons in the caudaI and ipsilateral sub-regions of the medial vestibular and prepositus nuclei. The results are discussed in terms of neuronal firing activity versus translational activity based on the asymmetrical expression of the Fos inducible transcription factor in the medial vestibular and prepositus nuclei. Although ubiquitous in the brain, transcription factors like Fos can serve localized and specific roles in sensory-specific adaptive stimuli. Antisense injections can be an effective procedure for localized intervention into complex physiological functions, e.g. vestibular compensation. (C) 1999 Elsevier Science B.V. C1 Univ Texas, Med Branch, Dept Otolaryngol, Galveston, TX 77555 USA. Univ Texas, Med Branch, Dept Physiol & Biophys, Galveston, TX 77555 USA. Univ Texas, Med Branch, Dept Anat & Neurosci, Galveston, TX 77555 USA. Univ Texas, Med Branch, Program Neurosci, Galveston, TX 77555 USA. NASA, Lyndon B Johnson Space Ctr, Natl Res Council, Houston, TX 77058 USA. RP Perachio, AA (reprint author), Univ Texas, Med Branch, Dept Otolaryngol, 7-102 Med Res Bldg,11th & Mechan St, Galveston, TX 77555 USA. OI Shinder, Michael/0000-0003-0420-8995 FU NIDCD NIH HHS [DC-00111] NR 25 TC 35 Z9 35 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0006-8993 J9 BRAIN RES JI Brain Res. PD JAN 30 PY 1999 VL 817 IS 1-2 BP 246 EP 255 DI 10.1016/S0006-8993(98)01284-0 PG 10 WC Neurosciences SC Neurosciences & Neurology GA 159XZ UT WOS:000078201800033 PM 9889379 ER PT J AU Ricca, A AF Ricca, A TI Accurate D-0 value for NF+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID COUPLED-CLUSTER THEORY; GAUSSIAN-BASIS SETS; AB-INITIO; ELECTRON CORRELATION; WAVE-FUNCTIONS; ENERGIES; MOLECULES AB An accurate D-0 value is computed for NF+ using the RCCSD(T) approach. The value is refined by extrapolation to the basis set limit and by accounting for core-valence correlation and spin-orbit effects, The best estimate for the dissociation energy (D-0) at 0 K is 127.61 +/- 1.0 kcal/mol and for the dissociation energy (D-0) at 298 K is 128.79 +/- 1.0 kcal/mol. (C) 1999 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Thermosci Inst, Moffett Field, CA 94035 USA. RP Ricca, A (reprint author), NASA, Ames Res Ctr, Thermosci Inst, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 25 TC 2 Z9 2 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JAN 29 PY 1999 VL 300 IS 1-2 BP 80 EP 84 DI 10.1016/S0009-2614(98)01380-3 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 163ER UT WOS:000078390700011 ER PT J AU Meyers, TR Thrower, F Short, S Lipson, K Joyce, J Farrington, C Doherty, S AF Meyers, TR Thrower, F Short, S Lipson, K Joyce, J Farrington, C Doherty, S TI Different prevalences of Renibacterium salmoninarum detected by ELISA in Alaskan chinook salmon Oncorhynchus tshawytscha spawned from freshwater and seawater SO DISEASES OF AQUATIC ORGANISMS LA English DT Article DE Renibacterium; ELISA; chinook ID BACTERIAL KIDNEY-DISEASE; IMMUNOSORBENT-ASSAY ELISA; ANTIGEN; FISHES AB Soluble antigen of Renibacterium salmoninarum (Rs) was detected by a polyclonal enzyme-linked immunosorbent assay (ELISA) at significantly higher prevalences in adult chinook salmon Oncorhynchus tshawytscha that matured in freshwater than in the same cohort of fish spawned after maturation in seawater. The cumulative results were consistent during 4 yr of comparison at the Little Port Walter Hatchery on Baranof Island, Alaska, USA. Possible causes for this difference are discussed. Maturation of chinook salmon broodstock in seawater has become a practical strategy at this hatchery to reduce the prevalence of Rs-positive parent fish and the numbers of culled eggs. C1 Natl Marine Fisheries Serv, Auke Bay Lab, Juneau, AK 99801 USA. Alaska Dept Fish & Game, Commercial Fisheries Div, Douglas, AK 99824 USA. So SE Reg Aquaculture Assoc, Ketchikan, AK 99901 USA. RP Meyers, TR (reprint author), Alaska Dept Fish & Game, Commercial Fisheries Div, POB 25526, Juneau, AK 99802 USA. NR 22 TC 8 Z9 8 U1 0 U2 3 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0177-5103 J9 DIS AQUAT ORGAN JI Dis. Aquat. Org. PD JAN 29 PY 1999 VL 35 IS 2 BP 101 EP 105 DI 10.3354/dao035101 PG 5 WC Fisheries; Veterinary Sciences SC Fisheries; Veterinary Sciences GA 185UX UT WOS:000079690200003 PM 10092972 ER PT J AU Rind, D Lean, J Healy, R AF Rind, D Lean, J Healy, R TI Simulated time-dependent climate response to solar radiative forcing since 1600 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GLOBAL CLIMATE; IRRADIANCE VARIATIONS; SURFACE-TEMPERATURE; MAUNDER MINIMUM; CO2 CLIMATE; MODEL; VARIABILITY; RECONSTRUCTION; SENSITIVITY; IMPACT AB Estimated solar irradiance variations since 1500 have been used to force the GISS atmospheric GCM coupled to a mixed layer "q-flux" ocean with heat diffusion through the bottom of the mixed layer. The goal is to assess solar-induced climate change in preindustrial and postindustrial epochs. Six simulations and control runs were made to test the effects of different initial conditions, estimates of initial solar forcing conditions, and ocean heat uptake. The results show that an estimated solar forcing increase of 0.25% accounts for a 0.45 degrees C temperature increase since 1600 and an increase of about 0.2 degrees C over the past 100 years. Global surface temperatures lag solar fluctuations by up to 10 years; the lag is greater over the oceans and so is the correlation due to reduced noise. With only a mixed layer ocean the phase lag is 5 years less. Solar forcing and water vapor feedback each directly account for 35% of the temperature response, with cloud cover changes contributing 20% and sea ice/snow cover 10%. Uncertainty in the initial radiation imbalance or solar forcing affects the surface temperatures for 60-90 years. Modeled and observed periodicities show dominance of long-period forcing (>50 years), as provided by the solar input in these experiments. Tropical temperatures correlate best with solar forcing, due to the influence of water vapor feedback, especially at these multidecadal periods. Sea ice and extratropical temperatures have less long-period power, while high-frequency fluctuations dominate simulated cloud cover variations, which are relatively independent of solar forcing changes. Global and extratropical precipitation increase as the climate warms, but not low and subtropical precipitation, due to conflicting influences of absolute temperature and temperature gradient changes. Solar forcing by itself was not sufficient to produce the rapid warming during the last several decades. A comparison experiment varying trace gas forcing suggests that if the solar estimate is correct, then negative forcing by tropospheric aerosols (and perhaps volcanoes, ozone, and land use changes) has been about -1.2 W m(-)2 since 1700, implying approximately equal contribution from direct and indirect tropospheric aerosol effects. C1 NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Ctr Climate Syst Res, New York, NY 10027 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RP NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. EM drind@giss.nasa.gov RI Healy, Richard/J-9214-2015; OI Healy, Richard/0000-0002-5098-8921; Lean, Judith/0000-0002-0087-9639 NR 45 TC 66 Z9 68 U1 0 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 1973 EP 1990 DI 10.1029/1998JD200020 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200003 ER PT J AU Yuan, XJ Martinson, DG Liu, WT AF Yuan, XJ Martinson, DG Liu, WT TI Effect of air-sea-ice interaction on winter 1996 Southern Ocean subpolar storm distribution SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC CIRCUMPOLAR CURRENT; HARMONIC STANDING WAVES; QUASI-STATIONARY WAVES; SOUTHWESTERN ROSS SEA; KATABATIC WIND REGIME; TERRA-NOVA BAY; ATMOSPHERIC CIRCULATION; WEDDELL SEA; MESOSCALE CYCLOGENESIS; POLAR LOWS AB Air-sea-ice interaction processes in the Southern Ocean are investigated utilizing space-observed surface winds, sea ice concentration, and sea surface temperature (SST) from September through December, 1996. The sea ice edge (SIE) shows three ice-extent maxima around the Antarctic during September and October when sea ice coverage is maximum. They are located in the central Indian Ocean, east of the Ross Sea, and in the eastern Weddell Gyre. During September and October, most of the strong and long lasting storms initiate northeast of the three sea ice maxima. Such spatial distributions of storms and sea ice reflect coupling processes of the air-sea-ice interaction. A relatively stable, wave number 3 atmospheric circulation pattern that is believed to be fixed by the land-ocean distribution prevails during the ice maximum season. The ice-extent maxima coincide with strong southerlies and divergent wind fields associated with this pattern, which suggests that the mean atmospheric circulation determines the ice distribution. The ice-extent maxima can enhance the regional meridional surface pressure gradient and therefore strengthen the westerly winds north of the ice edge. The decreasing ice extent east of the ice maxima creates a local zonal thermal gradient which enhances local southerlies. This positive feedback between the wave pattern in the mean atmospheric circulation and ice distribution partially causes the eastward propagation of the ice maxima and also provides a favorable condition for cyclogenesis northeast of the ice-extent maxima. The mechanism of the cyclogenesis is the baroclinic instability caused by the cold air blown from the ice pack to the warm open-ocean waters. Where the SST is warmest off the SIE and the southerlies are the strongest, the potential for cyclogenesis is most likely. This is consistent with the observations. C1 Columbia Univ, Lamont Doherty Geol Observ, Palisades, NY 10964 USA. CALTECH, Jet Prop Lab 300 323, Pasadena, CA 91109 USA. RP Columbia Univ, Lamont Doherty Geol Observ, Palisades, NY 10964 USA. EM xyuan@ldeo.columbia.edu; dgm@ldeo.columbia.edu; liu@pacific.jpl.nasa.gov NR 59 TC 26 Z9 27 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 1991 EP 2007 DI 10.1029/98JD02719 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200004 ER PT J AU Shay-El, Y Alpert, P da Silva, A AF Shay-El, Y Alpert, P da Silva, A TI Reassessment of the moisture source over the Sahara Desert based on NASA reanalysis SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PROJECT; DATASET AB The components of the moisture balance equation are calculated for the Middle East/North Africa regions based on NASA/GEOS-1 multiyear reanalysis data set. These include the Evaporation (E), Precipitation (P), moisture flux divergence (del.Q), and errors associated with the incremental analysis updates of the specific humidity, or IAU(q). The Annual mean del.Q corresponds well to the results of Vitart et al. [1996], based on NCEP data. IAU(q) reveals a strong moisture source over the eastern Mediterranean and also confirms the paradoxical net moisture sink over the Arabian-Iraqi desert found by Alpert and Shay-El [1993]. Over the North African Sahara Desert the moisture flux was shown to converge through the northern and southern boundaries mainly at low levels (similar to 900 hPa) and to diverge through the eastern and western boundaries at higher levels (similar to 700 hPa). Starr. and Peixoto [1958] have classified North Africa as a net moisture source. Area averaging of del.Q over a box with varying dimensions reveals that it can be classified as a net sink if the box is small enough and located over the center of the desert. If the box is big enough to include the boundaries of the continent only then can it be classified as net source or divergence zone. Inspection of the intermonthly and diurnal variability, as well as the model biases, weakens also the net source argument. It is suggested that the earlier finding of a net source might be due to the smoothing of the water/land boundary, or due to various atmospheric diffusion processes such as the sea breeze cycle and cloud intrusion and evaporation. C1 Tel Aviv Univ, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel. NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Tel Aviv Univ, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel. EM yuval@cyclone.tau.ac.il RI da Silva, Arlindo/D-6301-2012 OI da Silva, Arlindo/0000-0002-3381-4030 NR 34 TC 9 Z9 9 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2015 EP 2030 DI 10.1029/1998JD200003 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200006 ER PT J AU Pawson, S Kruger, K Swinbank, R Bailey, M O'Neill, A AF Pawson, S Kruger, K Swinbank, R Bailey, M O'Neill, A TI Intercomparison of two stratospheric analyses: Temperatures relevant to polar stratospheric cloud formation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NORTHERN STRATOSPHERE; DATA ASSIMILATION; TRENDS AB Two independent daily stratospheric data sets are compared for 16 northern winters. The objective is to assess the consistency of temperatures low enough for polar stratospheric cloud (PSC) formation at 50 hPa. The first data set is the subjective analysis produced from the radiosonde network at the "Freie Universitat Berlin" (FUB), which is constrained by hydrostatic and thermal wind balance. The second is the satellite-based analysis of geopotential height, compiled from the TIROS Operational Vertical Sounding-system by the United Kingdom Meteorological Office; temperatures are derived from the hypsometric equation. The stratospheric sounding units (SSU) provide most of the stratospheric data in that system. The FUB data are generally colder, particularly at low temperatures, but there is a large dispersion about the mean difference. The uncertainties of the values of the lowest temperatures are around 1 K and 2 K in the mean and rms, respectively. There may be a geographical bias in the data sets. There isa clear relationship between the vertical temperature gradient and the difference between the two data sets, the satellite-derived values becoming relatively colder when the temperature decreases at pressures lower than 50 hPa. Regarding PSC formation: adequately low temperatures occur more often in the FUB data, but on 25% of winter days the areas A(tau) where PSCs might form are larger in the SSU data. Seasonally integrated values of A(tau) show a fairly good agreement between the two data sets, the satellite-derived values generally being smaller. Both systems give stable and consistent estimates of the areas of low temperature at 50 hPa. On the basis of data quality alone, it is not possible to recommend either analysis system in preference to the other for studies of the coldness of the polar stratosphere. C1 United Kingdom Meteorol Off, Bracknell RG12 2SZ, Berks, England. Free Univ Berlin, Inst Meteorol, D-12165 Berlin, Germany. Univ Reading, Ctr Global Atmospher Modelling, Reading RG6 2AU, Berks, England. RP NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. EM pawson@polska.gsfc.nasa.gov RI Pawson, Steven/I-1865-2014 OI Pawson, Steven/0000-0003-0200-717X NR 13 TC 13 Z9 13 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2041 EP 2050 DI 10.1029/98JD02279 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200008 ER PT J AU Roberti, L Kummerow, C AF Roberti, L Kummerow, C TI Monte Carlo calculations of polarized microwave radiation emerging from cloud structures SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The last decade has seen tremendous growth in cloud dynamical and microphysical models that are able to simulate storms and storm systems with very high spatial resolution, typically of the order of a few kilometers. The fairly realistic distributions of cloud and hydrometeor properties that these models generate has, in turn, led to a renewed interest in the three-dimensional microwave radiative transfer modeling needed to understand the effect of cloud and rainfall inhomogeneities upon microwave observations. Monte Carlo methods and particularly backward Monte Carlo methods have shown themselves to be very desirable because of the quick convergence of the solutions. Unfortunately, backward Monte Carlo methods are not well suited to treat polarized radiation. This study reviews existing Monte Carlo methods and presents a new polarized Monte Carlo radiative transfer code. The code is based on a forward scheme but uses biasing techniques to keep the computational requirements equivalent to the backward solution. Radiative transfer computations have been performed using a microphysical-dynamical cloud model, and the results are presented together with the algorithm description. C1 Politecn Torino, Dipartimento Elettr, I-10129 Turin, Italy. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Politecn Torino, Dipartimento Elettr, Corso Duca Abruzzi 24, I-10129 Turin, Italy. EM roberti@polito.it; kummerow@agnes.gsfc.nasa.gov NR 25 TC 30 Z9 30 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2093 EP 2104 DI 10.1029/1998JD200038 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200013 ER PT J AU Strahan, SE Loewenstein, M Podolske, JR AF Strahan, SE Loewenstein, M Podolske, JR TI Climatology and small-scale structure of lower stratospheric N2O based on in situ observations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; POLAR VORTEX; SURF ZONE; TRANSPORT; AIRCRAFT; TRACER; ER-2; SPECTROMETER; METEOROLOGY; TROPOSPHERE AB We derive seasonal mean distributions of N2O as a function of latitude and height from in situ measurements made by the airborne tunable laser absorption spectrometer (ATLAS) instrument on board the NASA ER-2 aircraft. Seasonal means are also derived using an equivalent latitude coordinate which maximizes the information content and produces nearly pole-to-pole coverage. The mean N2O fields are consistent with the Brewer-Dobson circulation, showing tropospheric values of N2O entering the tropical lower stratosphere and low values at the winter hemisphere poles. The analysis presented here is intended for use as a climatology for two- and three-dimensional modelers wishing to evaluate the balance of transport processes affecting their models' lower stratosphere. We also present some interesting features that have been revealed by the high spatial resolution of the ATLAS measurements. These include large gradients of N2O observed at the equatorward and poleward edges of the surf zone and filaments less than 1 km thick identified during aircraft profiling. The results presented here demonstrate the unique nature and high value of aircraft in situ data sets. C1 Gen Sci Corp, Laurel, MD USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP NASA, Goddard Space Flight Ctr, Code 910-3, Greenbelt, MD 20771 USA. EM strahan@prometheus.gsfc.nasa.gov; mloewenstein@mail.arc.nasa.gov; jpodolske@mail.arc.nasa.gov RI Strahan, Susan/H-1965-2012 NR 40 TC 24 Z9 24 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2195 EP 2208 DI 10.1029/1998JD200075 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200023 ER PT J AU Russell, PB Hobbs, PV Stowe, LL AF Russell, PB Hobbs, PV Stowe, LL TI Aerosol properties and radiative effects in the United States East Coast haze plume: An overview of the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLIMATE; SULFATE; TRENDS AB Aerosol effects on atmospheric radiation are a leading source of uncertainty in predicting climate change. The Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) was designed to reduce this uncertainty by measuring and analyzing aerosol properties and effects on the United States eastern seaboard, where one of the world's major plumes of urban/industrial haze moves from the continent over the Atlantic Ocean. The TARFOX intensive field campaign was conducted July 10-31, 1996, It included coordinated measurements from four satellites (GOES-8, NOAA-14, ERS-2, Landsat), four aircraft (ER-2, C-130, C-131A, and a modified Cessna), land sites, and ships. A variety of aerosol conditions was sampled, ranging from relatively clean, behind frontal passages, to moderately polluted, with aerosol optical depths exceeding 0.5 at midvisible wavelengths. Gradients of aerosol optical thickness were sampled to aid in separating aerosol effects from other radiative effects and to more tightly constrain closure tests, including those of satellite retrievals, Early results from TARFOX include demonstration of the unexpected importance of carbonaceous compounds and water condensed on aerosol in the United States East Coast haze plume, chemical apportionment of the aerosol optical depth, measurements of aerosol-induced changes in upwelling and downwelling shortwave radiative fluxes, and generally good agreement between measured flux changes and those calculated from measured aerosol properties. This overview presents the TARFOX objectives, rationale overall experimental approach, and key initial findings as a guide to the more complete results reported in this special section and elsewhere. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Natl Environm Satellite Data & Informat Serv, NOAA, Satellite Res Lab, NSC, Washington, DC 20233 USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. RP NASA, Ames Res Ctr, MS 245-5, Moffett Field, CA 94035 USA. EM prussell@mail.ars.nasa.gov NR 50 TC 177 Z9 179 U1 1 U2 14 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2213 EP 2222 DI 10.1029/1998JD200028 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200026 ER PT J AU Remer, LA Kaufman, YJ Holben, BN AF Remer, LA Kaufman, YJ Holben, BN TI Interannual variation of ambient aerosol characteristics on the east coast of the United States SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SKY BRIGHTNESS MEASUREMENTS; AIR-POLLUTION AB We investigate the interannual variability of the seasonally recurring aerosol haze of the United States East Coast. The data consist of observations collected by five Sun/sky radiometer stations. We compare the data collected in 1996 in conjunction with the TARFOX experiment to similar data collected at the same locations in 1993. The regional mean optical thickness remains essentially constant in the two years. The Mount Pinatubo stratospheric mode decreases spectral dependence in 1993, especially for optical thickness below 0.20. The volume size distributions inverted from the sky measurements show an increase in accumulation mode particle size with increasing aerosol optical thickness in both years. At moderate to high optical thickness (tau(670)>0.20) the particles in the fine particle mode, 0.1-0.6 mu m radius range, from both years have the same lognormal parameters (r(m)=0.21, sigma=0.45-0.50). The volume of these particles increases linearly with tau. These size particles dominate the optical properties of the aerosol in the visible spectrum and cause remarkable interannual consistency in the aerosol optical characteristics. The 1993 and 1996 phase functions agree to within 7-10% for optical thicknesses greater than 0.2. C1 NASA, Atmospheres Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Terr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP NASA, Atmospheres Lab, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. EM remer@climate.gsfc.nasa.gov NR 17 TC 41 Z9 46 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2223 EP 2231 DI 10.1029/1998JD200037 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200027 ER PT J AU Veefkind, JP de Leeuw, G Durkee, PA Russell, PB Hobbs, PV Livingston, JM AF Veefkind, JP de Leeuw, G Durkee, PA Russell, PB Hobbs, PV Livingston, JM TI Aerosol optical depth retrieval using ATSR-2 and AVHRR data during TARFOX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HIGH-RESOLUTION RADIOMETER; RADIANCE; OCEAN; ALGORITHM; SYSTEM AB Satellite retrieved aerosol optical properties are compared to aircraft measurements for a case study during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). Two satellite instruments are used: the Along Track Scanning Radiometer 2 (ATSR-2) and the advanced very high resolution radiometer (AVHRR). The aerosol optical depth in the mid-visible (0.555 mu m) retrieved from the ATSR-2 data agrees within 0.03 with colocated sunphotometer measurements. Also, the spectral behavior of the aerosol optical depth is retrieved accurately. Good correlation is found between aerosol optical depths for AVHRR channel 1 (0.64 mu m) and sunphotometer derived values, but the satellite retrieved values are 0.05 to 0.15 lower. The Angstrom wavelength exponent is determined both from the ATSR-2 and the AVHRR data. The ATSR-2 derived Angstrom exponents are in good agreement with the values computed from the sunphotometer data. The Angstrom exponents determined from AVHRR data show very large variations. Both the ATSR-2 and the AVHRR aerosol optical depth images show a large gradient. Vertical profile data of temperature, relative humidity, and particle scattering indicate that this gradient is probably caused by changes in the dry aerosol properties, rather than a change in the relative humidity. C1 TNO, Phys & Elect Lab, NL-2609 JG The Hague, Netherlands. USN, Postgrad Sch, Dept Meteorol, Monterey, CA 93943 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. SRI Int, Menlo Pk, CA 94025 USA. RP TNO, Phys & Elect Lab, POB 96864, NL-2609 JG The Hague, Netherlands. EM veefkind@fel.tno.nl; deleeuw@fel.tno.nl NR 22 TC 32 Z9 33 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2253 EP 2260 DI 10.1029/98JD02816 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200030 ER PT J AU Tanre, D Remer, LA Kaufman, YJ Mattoo, S Hobbs, PV Livingston, JM Russell, PB Smirnov, A AF Tanre, D Remer, LA Kaufman, YJ Mattoo, S Hobbs, PV Livingston, JM Russell, PB Smirnov, A TI Retrieval of aerosol optical thickness and size distribution over ocean from the MODIS airborne simulator during TARFOX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SAHARAN DUST OUTBREAKS; ATMOSPHERIC CORRECTION; SPECTRAL RADIANCES; SATELLITE; REFLECTANCE; INFORMATION; INSTRUMENT; TURBIDITY; IMAGERY; PRODUCT AB Radiation and in-situ measurements collected during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) are used to test the method for remote sensing of aerosol properties and loading from the MODIS instrument. MODIS, a Moderate Resolution Imaging Spectroradiometer, will be launched in 1999 aboard the first EOS (Earth Observing System). Following the MODIS procedure [Tanre et al., 1997], the spectral radiance at the top of the atmosphere (TOA) measured over the ocean in a wide spectral range (0.55-2.13 mu m) is used to derive the aerosol optical thickness (proportional to the aerosol total loading) and the aerosol size distribution (integrated over the vertical column) of the ambient (undisturbed) aerosol by comparing measured radiances with values in look-up table (LUT). The LUT includes the gasphase oxidation accumulation mode, cloud-phase accumulation mode, and a coarse mode that represents maritime particles (salt) and dust. In each inversion, one accumulation and one coarse mode can be retrieved. The inversion retrieves the ratio of the contribution to the optical thicknesses of the two particle modes and the mean particle size that best fits the measurements. This algorithm is successfully applied to the data sets acquired during TARFOX. The MODIS airborne simulator (MAS) aboard the NASA ER-2 aircraft flew several times during the experiment above the University of Washington C-131A research aircraft on which the six-channel Ames Airborne Tracking Sun Photometer (AATS-6) was mounted. It flew also above surface-based Sun photometers. Optical thicknesses (at lambda = 550 nm) as well as the spectral dependence from the various data sets compare very well. C1 UST Lille, Opt Atmospher Lab, CNRS, UA 713, F-59655 Villeneuve Dascq, France. NASA, Atmospheres Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Applicat Int Corp, Vienna, VA 22180 USA. Univ Washington, Seattle, WA 98195 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Sci Syst & Applicat Inc, Terr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP UST Lille, Opt Atmospher Lab, CNRS, UA 713, F-59655 Villeneuve Dascq, France. EM Didier.Tanre@univ-lille1.fr; kaufman@climate.gsfc.nasa.gov RI Smirnov, Alexander/C-2121-2009 OI Smirnov, Alexander/0000-0002-8208-1304 NR 33 TC 63 Z9 66 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2261 EP 2278 DI 10.1029/1998JD200077 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200031 ER PT J AU Russell, PB Livingston, JM Hignett, P Kinne, S Wong, J Chien, A Bergstrom, R Durkee, P Hobbs, PV AF Russell, PB Livingston, JM Hignett, P Kinne, S Wong, J Chien, A Bergstrom, R Durkee, P Hobbs, PV TI Aerosol-induced radiative flux changes off the United States mid-Atlantic coast: Comparison of values calculated from sunphotometer and in situ data with those measured by airborne pyranometer SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OPTICAL DEPTH; SENSITIVITY; ASSUMPTIONS; INVERSION; MODEL; CODE AB The Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) measured a variety of aerosol radiative effects (including flux changes) while simultaneously measuring the chemical, physical, and optical properties of the responsible aerosol particles. Here we use TARFOX-determined aerosol and surface properties to compute shortwave radiative flux changes for a variety of aerosol situations, with midvisible optical depths ranging from 0.06 to 0.55. We calculate flux changes by several techniques with varying degrees of sophistication, in part to investigate the sensitivity of results to computational approach. We then compare computed flux changes to those determined from aircraft measurements. Calculations using several approaches yield downward and upward flux changes that agree with measurements. The agreement demonstrates closure (i.e., consistency) among the TARFOX-derived aerosol properties, modeling techniques, and radiative flux measurements. Agreement between calculated and measured downward flux changes is best when the aerosols are modeled as moderately absorbing (midvisible single-scattering albedos between about 0.89 and 0.93), in accord with independent measurements of the TARFOX aerosol. The calculated values for instantaneous daytime upwelling flux changes are in the range +14 to +48 W m(-2) for midvisible optical depths between 0.2 and 0.55. These values are about 39 to 100 times the global-average direct forcing expected for the global-average sulfate aerosol optical depth of 0.04. The reasons for the larger flux changes in TARFOX include the relatively large optical depths and the focus on cloud-free, daytime conditions over the dark ocean surface. These are the conditions that produce major aerosol radiative forcing events and contribute to any global-average climate effect. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SRI Int, Menlo Pk, CA 94025 USA. Meteorol Off, Meteorol Res Flight, DRA Farnborough, Farnborough GU14 6TD, Hants, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Dalhousie Univ, Dept Phys, Atmospher Sci Program, Halifax, NS B3H 3J5, Canada. Symtech Corp, Moffett Field, CA 94035 USA. USN, Postgrad Sch, Monterey, CA 93943 USA. Bay Area Environm Res Inst, San Francisco, CA 94122 USA. Univ Washington, Seattle, WA 98195 USA. RP NASA, Ames Res Ctr, MS 245-5, Moffett Field, CA 94035 USA. EM prussell@mail.arc.nasa.gov; kinne@spmer.gsfc.nasa.gov NR 30 TC 139 Z9 145 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 27 PY 1999 VL 104 IS D2 BP 2289 EP 2307 DI 10.1029/1998JD200025 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160QJ UT WOS:000078242200033 ER PT J AU Bryan, TC AF Bryan, TC TI Cheaper, faster docking SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Letter C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Bryan, TC (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU MCGRAW HILL INC PI NEW YORK PA 1221 AVENUE OF THE AMERICAS, NEW YORK, NY 10020 USA SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD JAN 25 PY 1999 VL 150 IS 4 BP 8 EP 8 PG 1 WC Engineering, Aerospace SC Engineering GA 161NQ UT WOS:000078295700005 ER PT J AU Smith, DE Zuber, MT Haberle, RM Rowlands, DD Murphy, JR AF Smith, DE Zuber, MT Haberle, RM Rowlands, DD Murphy, JR TI The Mars seasonal CO2 cycle and the time variation of the gravity field: A general circulation model simulation SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID RADIO OCCULTATION MEASUREMENTS; EARTHS GRAVITATIONAL-FIELD; ATMOSPHERIC MASS REDISTRIBUTION; TEMPORAL VARIATIONS; DUST STORMS; POLAR CAPS; TRACKING; LAGEOS; ROTATION; PATHFINDER AB We investigate the time variation of the long wavelength gravitational field of Mars due to mass redistribution associated with the annual cycle of CO2 exchange between the atmosphere and polar caps. Our analysis utilizes simulated monthly estimates of atmospheric pressure and CO2 polar frost as calculated by the NASA Ames general circulation model (GCM) for a "typical" year. We show that the deposition and sublimation of CO2 polar frost is expected to be the dominant effect on the gravity field at all low degrees. Variations in the amplitude and phase of time variations of gravity are sensitive to multiple factors, including polar elevation and the eccentricity of the Martian orbit. Phase effects associated with additive and competing influences at the summer and winter poles dictate that odd-numbered harmonic coefficients produce an annual signal in the gravity field while even-numbered coefficients show a semiannual signal. The predicted changes in the planetary flattening and pear-shaped terms of the field are at or above the noise level of expected X band Doppler tracking observations from Mars Global Surveyor and so could conceivably be detected from an orbital spacecraft. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Smith, DE (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Code 920, Greenbelt, MD 20771 USA. RI Rowlands, David/D-2751-2012 NR 67 TC 33 Z9 36 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 1999 VL 104 IS E1 BP 1885 EP 1896 DI 10.1029/1998JE900024 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 161JJ UT WOS:000078285200005 ER PT J AU Bauschlicher, CW Melius, CF Allendorf, MD AF Bauschlicher, CW Melius, CF Allendorf, MD TI Gallium compounds, a possible problem for the G2 approaches SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID COUPLED-CLUSTER THEORY; GAUSSIAN-BASIS SETS; ELECTRON CORRELATION; WAVE-FUNCTIONS; MOLECULES; ENERGIES; 1ST-ROW AB The G2 atomization energies of fluorine and oxygen containing Ga compounds are greatly in error. This arises from an inversion of the Ga 3d core orbital and the F 2s or O 2s valence orbitals. Adding the Ga 3d orbital to the correlation treatment or removing the F 2s orbitals from the correlation treatment are shown to eliminate the problem. Removing the O 2s orbital from the correlation treatment reduces the error, but it can still be more than 6 kcal/ mol. It is concluded that the experimental atomization energy of GaF2 is too large. (C) 1999 American Institute of Physics. [S0021-9606(99)30403-7]. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Sandia Natl Labs, Combust Res Facil, Livermore, CA 94551 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, STC-230-3, Moffett Field, CA 94035 USA. NR 26 TC 21 Z9 21 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JAN 22 PY 1999 VL 110 IS 4 BP 1879 EP 1881 DI 10.1063/1.477851 PG 3 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 156ZU UT WOS:000078034900005 ER PT J AU Stanimirovic, S Staveley-Smith, L Dickey, JM Sault, RJ Snowden, SL AF Stanimirovic, S Staveley-Smith, L Dickey, JM Sault, RJ Snowden, SL TI The large-scale H I structure of the Small Magellanic Cloud SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE turbulence; ISM : clouds; ISM : structure; galaxies : individual : Small Magellanic Cloud Magellanic Clouds; galaxies : structure ID PROPAGATING STAR-FORMATION; GALACTIC NEUTRAL HYDROGEN; INTERSTELLAR-MEDIUM; SPIRAL GALAXIES; POWER SPECTRUM; SUPER-NOVAE; SUPERSHELLS; SHELLS; GAS; SUPERBUBBLES AB We combine new Parkes telescope observations of neutral hydrogen (H I) in the Small Magellanic Cloud (SMC) with an Australia Telescope Compact Array (ATCA) aperture synthesis mosaic to obtain a set of images sensitive to all angular (spatial) scales between 98 arcsec (30 pc) and 4 degrees (4 kpc), The new data are used to study the H I spatial power spectrum over a range of contiguous scale sizes wider than those previously achieved in any other galaxy, including our own, The spatial power spectrum closely obeys the relation P(k) proportional to k(gamma), with gamma = -3.04 +/- 0.02, similar to values obtained by other authors for our own Galaxy which are in the range gamma = -3.0 to -2.8. This is surprising given the very different morphology, gas-richness, star-formation rate and evolution of the two systems, and may imply similar mechanisms for structure formation, One interpretation of the P(k) power-law is that the interstellar medium (ISM) of the SMC is fractal in nature, consisting of a hierarchy of H I cloud structures created, for example, by homogeneous turbulence. The projected fractal dimension of D-p = 1.5 is similar to values obtained by other authors for molecular clouds in the Galaxy in the size range similar to 0.05 to 100 pc. Such a model is consistent with a low space-filling factor for the neutral gas. A kinematic study of the H I data reveals the existence of three supergiant shells which were previously undetectable in the ATCA data alone, These shells have diameters up to 1.8 kpc and require energies (in the standard supernova-driven models) up to 2 x 10(54) erg. The structure and evolution of the ISM in the SMC are heavily influenced by the formation of these supergiant shells. C1 Univ Western Sydney Nepean, Kingswood, NSW 2747, Australia. CSIRO, Australia Telescope Natl Facil, Epping, NSW 2121, Australia. Univ Minnesota, Minneapolis, MN 55455 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Stanimirovic, S (reprint author), Univ Western Sydney Nepean, POB 10, Kingswood, NSW 2747, Australia. RI Staveley-Smith, Lister/A-1683-2011; Snowden, Steven/D-5292-2012; Dickey, John/C-6156-2013 OI Staveley-Smith, Lister/0000-0002-8057-0294; NR 68 TC 335 Z9 336 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JAN 21 PY 1999 VL 302 IS 3 BP 417 EP 436 DI 10.1046/j.1365-8711.1999.02013.x PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 165AD UT WOS:000078495300004 ER PT J AU Morley, R Church, MJ Smale, AP Balucinska-Church, M AF Morley, R Church, MJ Smale, AP Balucinska-Church, M TI Progressive covering of the accretion disc corona during dipping in the LMXB XB 1916-053 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; binaries : close; stars : individual : XB 1916-053; stars : neutron; X-rays : stars ID PHOTOELECTRIC ABSORPTION; EXO 0748-676; DIPS; DISCOVERY; INTENSITY; GINGA AB Results are reported for analysis of the extensive ROSAT observation of the dipping low-mass X-ray binary (LMXB) XB 1916-053, The dipping is 100 per cent deep showing that the emission regions are completely covered by the absorber. A good fit to the non-dip spectrum is obtained using a model consisting of a blackbody with kT(BB) = 1.95L(-0.34)(+0.74) keV and a power law with photon index 2.32 +/- 0.04. These components are identified with emission from the neutron star, and Comptonized emission from an extended accretion disc corona (ADC). Dip spectra are well-fitted by rapid absorption of the blackbody, and progressive covering of the extended component, as the absorber moves across the sourer, with a covering fraction that increases smoothly from 0 to similar to 1.0. Progressive covering shows that the Comptonized emission region is extended, consistent with it originating in the accretion disc corona. The strong unabsorbed component in the dip spectra is well-modelled as the uncovered part of the Comptonized emission at all stages of dipping. There is no detectable change in the low-energy cut-off of the spectrum in dipping which supports the identification of the unabsorbed part of the spectrum with the uncovered pan of the ADC emission. The absorbed part of the ADC emission is rapidly removed from the 0.1-2.0 keV band of the ROSAT Position Sensitive Proportional Counter (PSPC), which therefore selects only the uncovered part of the emission, and so the spectral evolution in dipping as viewed by the PSPC depends only on the covering fraction, determined by the geometric overlap between the source and absorber. C1 Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Morley, R (reprint author), Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. NR 14 TC 8 Z9 8 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JAN 21 PY 1999 VL 302 IS 3 BP 593 EP 598 DI 10.1046/j.1365-8711.1999.02188.x PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 165AD UT WOS:000078495300019 ER PT J AU Buratti, BJ Hicks, MD Newburn, RL AF Buratti, BJ Hicks, MD Newburn, RL TI Does global warming make Triton blush? SO NATURE LA English DT Letter C1 CALTECH, Jet Prop Lab, Palomar Observ, Pasadena, CA 91109 USA. RP Buratti, BJ (reprint author), CALTECH, Jet Prop Lab, Palomar Observ, 4800 Oak Grove Dr,183-501, Pasadena, CA 91109 USA. NR 9 TC 18 Z9 18 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 21 PY 1999 VL 397 IS 6716 BP 219 EP 219 DI 10.1038/16615 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 159QH UT WOS:000078184800036 ER PT J AU Flesia, C Korb, CL AF Flesia, C Korb, CL TI Theory of the double-edge molecular technique for Doppler lidar wind measurement SO APPLIED OPTICS LA English DT Article ID MIDDLE ATMOSPHERE; BACKSCATTER AB The theory of the double-edge lidar technique for measuring the wind with molecular backscatter is described. Two high-spectral-resolution edge filters are located in the wings of the Rayleigh-Brillouin profile. This doubles the signal change per unit Doppler shift, the sensitivity, and improves measurement accuracy relative to the single-edge technique by nearly a factor of 2. The use of a crossover region where the sensitivity of a molecular- and an aerosol-based measurement is equal is described. Use of this region desensitizes the molecular measurement to the effects of aerosol scattering over a velocity range of +/-100 m/s. We give methods for correcting short-term, shot-to-shot, frequency jitter and drift with a laser reference frequency measurement and methods for long-term frequency correction with a servo control system. The effects of Rayleigh-Brillouin scattering on the measurement are shown to be significant and are included in the analysis. Simulations for a conical scanning satellite-based lidar at 355 nm show an accuracy of 2-3 m/s for altitudes of 2-15 km for a 1-km vertical resolution, a satellite altitude of 400 km, and a 200 km x 200 km spatial resolution. (C) 1999 Optical Society of America. C1 Univ Geneva, Appl Phys Grp, CH-1211 Geneva 04, Switzerland. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Flesia, C (reprint author), Univ Geneva, Appl Phys Grp, 20 Rue Ecole Med, CH-1211 Geneva 04, Switzerland. EM flesia@sc2a.unige.ch; korb@agnes.gsfc.nasa.gov NR 17 TC 74 Z9 109 U1 3 U2 12 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD JAN 20 PY 1999 VL 38 IS 3 BP 432 EP 440 DI 10.1364/AO.38.000432 PG 9 WC Optics SC Optics GA 160QT UT WOS:000078243000003 PM 18305631 ER PT J AU Wang, MH AF Wang, MH TI Atmospheric correction of ocean color sensors: computing atmospheric diffuse transmittance SO APPLIED OPTICS LA English DT Article ID WATER-LEAVING RADIANCE; PHYTOPLANKTON AB Using the reciprocal equation derived by Yang and Gordon [Appl. Opt. 36, 7887-7897 (1997)] for atmospheric diffuse transmittance of the ocean-atmosphere system, I examined the accuracy of an analytical equation proposed by Gordon et al. [Appl. Opt. 22, 20-36 (1983)] in computing the atmospheric diffuse transmittance for wavelengths hom 412 to 865 nm for both a pure Rayleigh and a two-layer Rayleigh-aerosol atmosphere overlying a flat Fresnel-reflecting ocean surface. It was found that for viewing angles up to approximately 40 degrees, the analytical formula produces errors usually between 2% and 3% for nonabsorbing and weakly absorbing aerosols and for aerosol optical thicknesses tau(alpha) less than or equal to 0.4. The error increases with an increase in aerosol absorption, aerosol optical thickness, and viewing angle, and with the decrease of wavelength. By a simple numerical fit to modify the analytical formula, the atmospheric diffuse transmittance can be accurately computed usually to within similar to 1% (similar to 0.5% in most cases) for a variety of aerosol models, aerosol optical thicknesses tau(alpha) less than or equal to 0.6, viewing angles a theta less than or equal to 60 degrees, different aerosol vertical structure distribution, and for wavelengths from 412 to 865 nm. (C) 1999 Optical Society of America. C1 Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wang, MH (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Code 970-2, Greenbelt, MD 20771 USA. EM wang@simbios.gsfc.nasa.gov RI Wang, Menghua/F-5631-2010 OI Wang, Menghua/0000-0001-7019-3125 NR 8 TC 26 Z9 28 U1 0 U2 1 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 JAN 20 PY 1999 VL 38 IS 3 BP 451 EP 455 DI 10.1364/AO.38.000451 PG 5 WC Optics SC Optics GA 160QT UT WOS:000078243000005 PM 18305633 ER PT J AU Gregg, WW AF Gregg, WW TI Initial analysis of ocean color data from the ocean color and temperature scanner. I. Imagery analysis SO APPLIED OPTICS LA English DT Article ID ALGORITHM; SENSORS AB The ocean color and temperature scanner (OCTS) collected global ocean color data from November 1996 to June 1997. Analyses of OCTS imagery indicate three features that impair scientific research uses: (1) band misalignments, (2) image striping, and (3) image noise. These are due to (1) band offsets in the sensor design, (2) detector radiometric response variability, and (3) primarily cloud contamination, respectively. Methods are analyzed to ameliorate the effects of each that facilitate use of OCTS ocean color data for quantitative scientific analyses. C1 NASA, Lab Hydrospher Proc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gregg, WW (reprint author), NASA, Lab Hydrospher Proc, Goddard Space Flight Ctr, Code 971, Greenbelt, MD 20771 USA. EM gregg@cabin.gsfc.nasa.gov 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 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD JAN 20 PY 1999 VL 38 IS 3 BP 476 EP 485 DI 10.1364/AO.38.000476 PG 10 WC Optics SC Optics GA 160QT UT WOS:000078243000008 PM 18305636 ER PT J AU Hoge, FE Wright, CW Lyon, PE Swift, RN Yungel, JK AF Hoge, FE Wright, CW Lyon, PE Swift, RN Yungel, JK TI Satellite retrieval of inherent optical properties by inversion of an oceanic radiance model: a preliminary algorithm SO APPLIED OPTICS LA English DT Article ID DISSOLVED ORGANIC-MATTER; WATER RAMAN BACKSCATTER; PASSIVE CORRELATION SPECTROSCOPY; WARM CORE RING; ABSORPTION-COEFFICIENT; FLUORESCENCE MEASUREMENTS; COLOR MEASUREMENT; ATLANTIC BIGHT; AIRBORNE; PHYTOPLANKTON AB A previously published radiance model inversion theory has been field tested by using airborne water-leaving radiances to retrieve the chromophoric dissolved organic matter (CDOM) and detritus absorption coefficient, the phytoplankton absorption coefficient, and the total backscattering coefficient. The radiance model inversion theory was tested for potential satellite use by comparing two of the retrieved inherent optical properties with concurrent airborne laser-derived truth data. It was found that (1) matrix inversion of water-leaving radiances is well conditioned even in the presence of instrument-induced noise, (2) retrieved CDOM and detritus and phytoplankton absorption coefficients are both in reasonable agreement with absorption coefficients derived from airborne laser-induced fluorescence spectral emissions, (3) the total backscattering retrieval magnitude and variability are consistent with expected values for the Middle Atlantic Bight, and (4) the algorithm performs reasonably well in Sargasso Sea, Gulf Stream, slope, and shelf waters but is less consistent in coastal waters. (C) 1999 Optical Society of America. C1 NASA, Wallops Isl, VA 23337 USA. EG&G Inc, Wallops Isl, VA 23337 USA. RP Hoge, FE (reprint author), NASA, Wallops Flight Facil,Bldg N159, Wallops Isl, VA 23337 USA. NR 38 TC 33 Z9 36 U1 2 U2 2 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 JAN 20 PY 1999 VL 38 IS 3 BP 495 EP 504 DI 10.1364/AO.38.000495 PG 10 WC Optics SC Optics GA 160QT UT WOS:000078243000010 PM 18305638 ER PT J AU Hart, RC Balla, RJ Herring, GC AF Hart, RC Balla, RJ Herring, GC TI Nonresonant referenced laser-induced thermal acoustics thermometry in air SO APPLIED OPTICS LA English DT Article ID GAS-PHASE; ROTATIONAL CARS; STANDARD AIR; SOUND; SPEED; TEMPERATURE; PRESSURE; ABSORPTION; GRATINGS AB We report a detailed investigation of nonresonant laser-induced thermal acoustics (LITA) for the single-shot measurement of the speed of sound (vs) in an oven containing room air. A model for the speed of sound that includes important acoustic relaxation effects is used to convert the speed of sound into temperature. A reference LITA channel is used to reduce uncertainties in upsilon(S). Comparing thermocouple temperatures with temperatures deduced from our vs measurements and model, we find the mean temperature difference from 300 to 650 K to be 1% (+/-2 sigma). The advantages of using a reference LITA channel are discussed. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hart, RC (reprint author), NASA, Langley Res Ctr, Mail Stop 493, Hampton, VA 23681 USA. EM r.j.balla@larc.nasa.gov NR 46 TC 28 Z9 28 U1 0 U2 2 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 JAN 20 PY 1999 VL 38 IS 3 BP 577 EP 584 DI 10.1364/AO.38.000577 PG 8 WC Optics SC Optics GA 160QT UT WOS:000078243000022 PM 18305650 ER PT J AU Ma, QC Tipping, RH Boulet, C Bouanich, JP AF Ma, QC Tipping, RH Boulet, C Bouanich, JP TI Theoretical far-wing line shape and absorption for high-temperature CO2 SO APPLIED OPTICS LA English DT Article ID WATER CONTINUUM ABSORPTION; BAND; SPECTRA; REGION; CM-1 AB Theoretical results for the far-wing line shapes and corresponding absorption coefficients in the high-frequency wing of the nu(3) fundamental band of self-broadened CO2 are presented for a humber of temperatures between 218 and 751 K. These first-principles calculations are made assuming binary collisions within the framework of a quasi-static theory with a more accurate interaction potential than in previous calculations. The theoretical results are compared with existing laboratory data and are in good agreement for all the temperatures considered. (C) 1999 Optical Society of America. C1 Columbia Univ, Dept Appl Phys, New York, NY 10025 USA. NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Univ Paris 11, Lab Phys Mol & Applicat, CNRS, F-91405 Orsay, France. RP Ma, QC (reprint author), Columbia Univ, Dept Appl Phys, 2880 Broadway, New York, NY 10025 USA. EM qma@giss.nasa.gov NR 19 TC 21 Z9 25 U1 0 U2 1 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 JAN 20 PY 1999 VL 38 IS 3 BP 599 EP 604 DI 10.1364/AO.38.000599 PG 6 WC Optics SC Optics GA 160QT UT WOS:000078243000025 PM 18305653 ER PT J AU Jimenez, R Kashlinsky, A AF Jimenez, R Kashlinsky, A TI Galaxy evolution, deep galaxy counts, and the near-infrared cosmic infrared background SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : theory; diffuse radiation; galaxies : evolution; galaxies : statistics; galaxies : stellar content; large-scale structure of universe ID HIGH-REDSHIFT GALAXIES; COBE DIRBE MAPS; ELLIPTIC GALAXIES; LUMINOSITY FUNCTION; CHEMICAL EVOLUTION; GLOBULAR-CLUSTERS; FUNDAMENTAL PLANE; POWER SPECTRUM; DISK GALAXIES; LIGHT AB Accurate synthetic models of stellar populations are constructed and used in evolutionary models of stellar populations in forming galaxies. Following their formation, the late-type galaxies are assumed to follow the Schmidt law for star formation, while early-type galaxies are normalized to the present-day fundamental plane relations assumed to mimic the metallicity variations along their luminosity sequence. The stars in disks of galaxies are distributed with the Scale IMF and in spheroids with the Salpeter IMF. We show that these assumptions reproduce extremely well the recent observations for the evolution of the rate of star formation with redshift. We then compute predictions of these models for the observational data at early epochs for various cosmological parameters Omega, Omega(Lambda), and H-0. We find good match to the metallicity data from the damped Ly alpha systems and the evolution of the luminosity density out to z similar or equal to 1. Likewise, our models produce good fits for low values of Omega to the deep number counts of galaxies in all bands where data are available; this is done without assuming existence of extra populations of galaxies at high z. Our models also match the data on the redshift distribution of galaxy counts in B and K bands. They also provide good fits to the observed colors. We compute the predicted mean levels and angular distribution of the cosmic infrared background produced from the early evolution of galaxies. The predicted fluxes and fluctuations are still below the current observational limits, but not by a large factor. Finally, we find that the recent detection of the diffuse extragalactic light in the visible bands requires for our models a high redshift of galaxy formation, z(f) greater than or equal to (3-4); otherwise, the produced flux of the extragalactic light at optical bands exceeds the current observational limits. C1 Univ Edinburgh, Royal Observ, Astron Inst, Edinburgh EH9 3JH, Midlothian, Scotland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NORDITA, DK-2100 Copenhagen, Denmark. Theoret Astrophys Ctr, DK-2100 Copenhagen, Denmark. RP Jimenez, R (reprint author), Univ Edinburgh, Royal Observ, Astron Inst, Blackford Hill, Edinburgh EH9 3JH, Midlothian, Scotland. OI Jimenez, Raul/0000-0002-3370-3103 NR 93 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 16 EP 33 DI 10.1086/306648 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900003 ER PT J AU Davis, DS Mulchaey, JS Mushotzky, RF AF Davis, DS Mulchaey, JS Mushotzky, RF TI The enrichment history of hot gas in poor galaxy groups SO ASTROPHYSICAL JOURNAL LA English DT Article DE dark matter; galaxies : ISM; intergalactic medium; X-rays : galaxies ID X-RAY-EMISSION; ELLIPTIC GALAXIES; METAL ABUNDANCE; COMPACT-GROUPS; RICH CLUSTERS; MASS-LOSS; H-I; EVOLUTION; IRON; WINDS AB We have analyzed the ASCA SIS and GIS data for 17 groups and determined the average temperature and abundance of the hot X-ray-emitting gas. For groups with gas temperatures less than 1.5 keV, we find that the abundance is correlated with the gas temperature and luminosity. We have also determined the abundance of the alpha-elements and iron independently for those groups with sufficient counts. We find that for the cool groups (i.e., kT < 1.5 keV) the ratio of alpha-elements to iron is similar to 1, which is about half that seen in clusters. Spectral fits with the S, Si, and Fe abundances allowed to vary separately suggest the S/Fe ratio is similar to that seen in clusters, while the Si/Fe ratio in groups is half the value determined for richer systems. The mass of metals per unit of blue luminosity drops rapidly in groups as the temperature drops. There are two possible explanations for this decrease. One is that the star formation in groups is very different from that in rich clusters. The other explanation is that groups lose much of their enriched material via winds during the early evolution of ellipticals. If the latter is true, we find that poor groups will have contributed significantly (roughly one-third of the metals) to the enrichment of the intergalactic medium. C1 MIT, Ctr Space Res NE80 6003, Cambridge, MA 02139 USA. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Davis, DS (reprint author), MIT, Ctr Space Res NE80 6003, 77 Massachusetts Ave, Cambridge, MA 02139 USA. NR 36 TC 44 Z9 44 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 34 EP 40 DI 10.1086/306665 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900004 ER PT J AU Hough, DH Zensus, JA Vermeulen, RC Readhead, ACS Porcas, RW Rius, A Rector, TA Lenz, GC Davis, MA Snowdall, JC AF Hough, DH Zensus, JA Vermeulen, RC Readhead, ACS Porcas, RW Rius, A Rector, TA Lenz, GC Davis, MA Snowdall, JC TI Deep 8.4 GHz VLBI images of seven faint nuclei in lobe-dominated quasars SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : jets; galaxies : structure; quasars : general; radio continuum : galaxies; techniques : interferometric ID ACTIVE GALACTIC NUCLEI; EXTRAGALACTIC RADIO-SOURCES; PARSEC-SCALE JET; SUPERLUMINAL MOTION; 5-KM TELESCOPE; STATISTICS; MODELS; INTERFEROMETRY; VARIABILITY; COSMOLOGY AB We present deep 8.4 GHz VLBI images of the faint nuclei in seven lobe-dominated quasars (LDQs): 3C 175, 3C 204, 3C 205, 3C 215, 3C 351, 0821+447, and 0839+616. These images, made from data obtained in 1988 and 1991 with high-sensitivity VLBI arrays, have a typical rms noise level of similar to 0.03 mJy per beam and resolution of similar to 0.5 mas. The parsec-scale jet structures are generally greater in extent and complexity than those seen on many previous, less sensitive maps of other LDQ nuclei; the jet in 3C 204 bends through at least 10 degrees, and the jet in 3C 205 extends out to similar to 5 mas. Observations of 3C 204, 3C 205, and 0839 + 616 at two epochs reveal clear flux density variability in 3C 204 and 3C 205, but none of these sources shows any evidence for outward motion of jet components; their mean apparent transverse velocity is (-0.47 +/- 0.43)h(-1)c, from which we determine a 3 sigma upper limit on their mean expansion speed of similar to 0.8 h(-1)c (H-0 = 100 h km s(-1) Mpc(-1), q(0) = 0.5). The innermost jet knot in 3C 204 underwent a marginal position angle swing away from the mean jet axis. We also present the first 8.4 GHz A-array VLA images for all the objects except 3C 351. All the sources except 0821+447 display one-sided VLBI and VLA jets, which lie on the same side of the VLBI core and are generally well aligned (to within similar to 5 degrees). In addition, we analyze the statistics of projected linear size, relative nuclear strength, and misalignment angle for the 3CR and Jodrell Bank LDQ samples. We conclude that our results are generally consistent with a fairly simple relativistic jet model and with the unification of core-dominated quasars, lobe-dominated quasars, and possibly even powerful radio galaxies; there is a marginal suggestion that the quasars in our samples have a restricted range of angles to the line of sight (e.g., 0 degrees to similar to 45 degrees). C1 Trinity Univ, Dept Phys, San Antonio, TX 78212 USA. Max Planck Inst Radioastron, D-53121 Bonn, Germany. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. Netherlands Fdn Res Astron, NL-7990 AA Dwingeloo, Netherlands. Inst Estudis Espacias Catalunya, E-08034 Barcelona, Spain. NASA, Inst Nacl Pesquisas Espaciais, E-28020 Madrid, Spain. Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. CALTECH, Jet Prop Lab, Telos Informat Syst, Pasadena, CA 91109 USA. RP Hough, DH (reprint author), Trinity Univ, Dept Phys, 715 Stadium Dr, San Antonio, TX 78212 USA. RI Antonio, Rius/A-4873-2012 OI Antonio, Rius/0000-0002-5947-2649 NR 64 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 84 EP 104 DI 10.1086/306645 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900008 ER PT J AU Bautista, MA Titarchuk, L AF Bautista, MA Titarchuk, L TI H-like iron emission in narrow-line Seyfert 1 galaxies as a temperature diagnostic of accretion flows SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies : active; galaxies : Seyfert; radiation mechanisms : thermal ID ADVECTION-DOMINATED ACCRETION; BLACK-HOLES AB We study the formation of the I-I-like iron (Fe XXVI) Ly alpha line at 6.97 keV in narrow-line Seyfert 1 galaxies in the framework of current models for accretion into a black hole. We find that Fe XXVI Ly alpha emission is most likely formed by resonant fluorescence resulting from the strong radiation field in the region near the black hole, or possibly in the interphase between a hot corona and the optically thick or disk. Alternatively, the line could be formed by collisional excitation at a temperature of approximately 12 keV in accretion flows dominated by advection or gravitational accretion flows with strong shocks. For either resonant fluorescence or collisional excitation, the equivalent width of the Fe XXVI Lya line is a powerful temperature diagnostic of the emitting region. We propose some observational tests to distinguish between collisional and resonant fluorescent excitation of the line. C1 NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. George Mason Univ, Inst Comp Sci & Informat, Fairfax, VA 22030 USA. RP Bautista, MA (reprint author), NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. NR 26 TC 8 Z9 8 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 105 EP 111 DI 10.1086/306670 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900009 ER PT J AU Turner, TJ AF Turner, TJ TI X-ray observations of Markarian 231 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Markarian 231); galaxies : nuclei; X-rays : galaxies ID BROAD ABSORPTION-LINE; FE-II EMISSION; ULTRALUMINOUS INFRARED GALAXIES; ACTIVE GALACTIC NUCLEI; ECHELLE SPECTROSCOPY; LUMINOSITY FUNCTION; QUASARS; SPECTRUM; OBJECTS AB This paper presents new X-ray observations of Mrk 231, an active galaxy of particular interest because of its large infrared luminosity and the presence of several blueshifted broad absorption line (BAL) systems, a phenomenon observed in a small fraction of QSOs. A ROSAT HRI image of Mrk 231 is presented, which shows an extended region of soft X-ray emission covering several tens of kiloparsecs, consistent with the extent of the host galaxy. An ASCA observation of Mrk 231 is also presented. Hard X-rays are detected, but the data show no significant variability in X-ray flux. The hard X-ray continuum is heavily attenuated, and X-ray column estimates range from similar to 2 x 10(22) to 10(23) cm(-2), depending on whether the material is assumed to be neutral or ionized, and depending on the model assumed for the extended X-ray component. These ASCA data provide only the second hard X-ray spectrum of a BAL active galactic nucleus presented to date. The broadband spectral energy distribution of the source is discussed. While Mrk 231 is X-ray weak compared to Seyfert 1 galaxies, it has an optical-to-X-ray spectrum typical of a QSO. C1 NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. RP Turner, TJ (reprint author), Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. NR 38 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 142 EP 148 DI 10.1086/306674 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900013 ER PT J AU Tatischeff, V Ramaty, R AF Tatischeff, V Ramaty, R TI Diffuse 0.5-1 keV X-rays and nuclear gamma rays from fast particles in the local hot bubble SO ASTROPHYSICAL JOURNAL LA English DT Article DE diffuse radiation; gamma rays : theory; ISM : bubbles; X-rays : ISM ID GAS; SUPERNOVA; SPECTRUM; SHADOWS; ORION; LINES; STARS AB We show that interactions of fast particles with the boundary shell of the local hot bubble could make an important contribution to the 0.5-1 keV diffuse X-ray background observed with ROSAT. The bulk of these nonthermal X-rays are due to line emission from fast O ions of energies around 1 MeV nucleon-l The unequivocal signature of lines from de-excitations in fast ions is their large width (delta E/E similar or equal to 0.1 for O lines), which distinguishes them from X-ray lines produced in a hot plasma. If the 0.5-1 keV nonthermal X-rays are produced by accelerated particles with a sufficiently hard energy spectrum, the gamma-ray line emission produced in the boundary shell of the local hot bubble could account for the recently reported COMPTEL observations of nuclear gamma-ray lines from a broad region toward the Galactic center. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Tatischeff, V (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 30 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 204 EP 207 DI 10.1086/306658 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900019 ER PT J AU Schultz, ASB Colgan, SWJ Erickson, EF Kaufman, MJ Hollenbach, DJ O'Dell, CR Young, ET Chen, H AF Schultz, ASB Colgan, SWJ Erickson, EF Kaufman, MJ Hollenbach, DJ O'Dell, CR Young, ET Chen, H TI NICMOS narrowband images of OMC-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE H II regions; infrared : ISM : lines and bands; ISM : individual (OMC-1); ISM : jets and outflows; stars : pre-main-sequence ID ORION MOLECULAR CLOUD; HERBIG-HARO OBJECTS; NEBULA; EMISSION; REGION; KL AB We present images of a 90 " x 90 " field centered on the Becklin-Neugebauer object (BN) in OMC-1, taken with the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) aboard the Hubble Space Telescope. The observed lines are H-2 1-0 S(1), Pa alpha, [Fe II] 1.64 mu m, and the adjacent continua. The region is rich in interesting structures. The most remarkable are streamers of H-2 emission that extend from 15 " to 50 " from IRc2, seen here in unprecedented detail. Unlike the northern H-2 "fingers," these inner structures do not exhibit significant [Fe II] emission at their tips, which we suggest is due to lower excitation. These observations also show that the morphological details of the Pa alpha and [Fe II] emission (both imaged for the first time in this region) bear a striking resemblance to that of the H alpha and [S II] emission previously observed with WFPC2. This implies that these IR and optical lines are produced by radiative excitation on the surface of the molecular cloud. The Pa alpha morphology of III-I 202 is also very similar to its H alpha and [O III] emission, again suggesting that the extended Pa alpha emission in this object is photoexcited by the Trapezium, as has been suggested for the optical emission. We find evidence of shock-excited [Fe II] in HH 208, where it again closely follows the morphology of [S II]. There is also H-2 coincident with the [S II] and [Fe II] emission, which may be associated with HH 208. Finally, we note some interesting continuum features: diffuse "tails" trailing from IRc3 and IRc4, more extensive observations of the "crescent" found by Stolovy et al., and new observations of a similar oval object nearby. We also find a V-shaped region that may be the boundary of a cavity being cleared by IRc2. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Rice Univ, Dept Space Phys & Astron, Houston, TX 77005 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. RP Schultz, ASB (reprint author), SETI Inst, Mt View, CA USA. RI Colgan, Sean/M-4742-2014 NR 20 TC 52 Z9 52 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 282 EP 288 DI 10.1086/306680 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900027 ER PT J AU Laurent, P Titarchuk, L AF Laurent, P Titarchuk, L TI The converging inflow spectrum is an intrinsic signature for a black hole: Monte Carlo simulations of Comptonization on free-falling electrons SO ASTROPHYSICAL JOURNAL LA English DT Article DE black hole physics; radiation mechanisms : nonthermal; X-rays : general ID X-RAY; ANGULAR-DISTRIBUTION; SPHERICAL ACCRETION; RADIATION; MODELS; DISKS AB An accreting black hole is, by definition, characterized by the drain. Namely, matter falls into a black hole much the same way as water disappears down a drain: matter goes in and nothing comes out. As this can only happen in a black hole, it provides a way to see "a black hole," a unique observational signature of black holes. The accretion proceeds almost in a free-fall manner close to the black hole horizon, where the strong gravitational field dominates the pressure forces. In this paper we calculate (by using Monte Carlo simulations) the specific features of X-ray spectra formed as a result of upscattering of the soft (disk) photons in the converging inflow (CI) within about 3 Schwarzschild radii of the black hole. The full relativistic treatment has been implemented to reproduce these spectra. We show that spectra in the soft state of black hole systems (BHS) can be described as the sum of a thermal (disk) component and the convolution of some fraction of this component with the CI upscattering spread (Green's) function. The latter boosted photon component is seen as an extended power law at energies much higher than the characteristic energy of the soft photons. We demonstrate the stability of the power spectral index (alpha = 1.8 +/- 0.1) over a wide range of the plasma temperature, 0-10 keV, and mass accretion rates (higher than 2 in Eddington units). We also demonstrate that the sharp high-energy cutoff occurs at energies of 200-400 keV, which are related to the average energy of electrons m(e)c(2) impinging on the event horizon. The spectrum is practically identical to the standard thermal Comptonization spectrum (Hua & Titarchuk) when the CI plasma temperature is getting of order of 50 keV (the typical ones for the hard state of BHS). In this case one can see the effect of the bulk motion only at high energies, where there is an excess in the CI spectrum with respect to the pure thermal one. Furthermore, we demonstrate that the change of spectral shapes from the soft X-ray state to the hard X-ray slate is clearly to be related to the temperature of the bulk flow. We derive a generic formula for the temperature of the emitting region (CI) that depends on the ratio of the energy release in this very region and in the disk. Using this formula, we demonstrate that the temperature of the emission region in the hard state of the BHS is approximately 2 times higher than the ones of neutron star systems (NSS) in the hard state, which is confirmed by recent RXTE and Beppo-SAX observations of the hard state of NSS. The effect of the bulk Comptonization compared with the thermal one is getting stronger when the plasma temperature drops below 10 keV. These Monte Carlo simulated CI spectra are an inevitable stamp of the BHS where the strong gravitational field dominates the pressure forces. C1 CEA Saclay, SAP, DAPNIA, DSM, F-91191 Gif Sur Yvette, France. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. George Mason Univ, Inst Computat Sci & Informat, Fairfax, VA 22030 USA. RP Laurent, P (reprint author), CEA Saclay, SAP, DAPNIA, DSM, F-91191 Gif Sur Yvette, France. RI laurent, philippe/E-6211-2013 NR 31 TC 92 Z9 92 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 289 EP 297 DI 10.1086/306683 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900028 ER PT J AU Contopoulos, I Kazanas, D Fendt, C AF Contopoulos, I Kazanas, D Fendt, C TI The axisymmetric pulsar magnetosphere SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; pulsars : general; stars : magnetic fields ID DRIVEN RELATIVISTIC JETS; GAMMA-RAY PULSARS; ROTATING MAGNETOSPHERES; OUTER MAGNETOSPHERE; MODEL; RADIATION; WIND AB We present, for the first time, the structure of the axisymmetric force-free magnetosphere of an aligned rotating magnetic dipole, in the case in which there exists a sufficiently large charge density (whose origin we do not question) to satisfy the ideal MHD condition, E.B = 0, everywhere. The unique distribution of electric current along the open magnetic field lines that is required for the solution to be continuous and smooth is obtained numerically. With the geometry of the field lines thus determined, we compute the dynamics of the associated MHD wind. The main result is that the relativistic outflow contained in the magnetosphere is not accelerated to the extremely relativistic energies required for the flow to generate gamma rays. We expect that our solution will be useful as the starting point for detailed studies of pulsar magnetospheres under more general conditions, namely, when the force-free and/or the ideal MHD condition, E.B = 0, are not valid in the entire magnetosphere. Based on our solution, we consider that the most likely positions of such an occurrence are the polar cap, the crossings of the zero space charge surface by open field lines, and the return current boundary, but not the light cylinder. C1 Univ Crete, Dept Phys, Heraklion 71003, Greece. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Astrophys Inst Potsdam, D-14482 Potsdam, Germany. RP Contopoulos, I (reprint author), Univ Crete, Dept Phys, POB 2208, Heraklion 71003, Greece. NR 27 TC 235 Z9 235 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 351 EP 358 DI 10.1086/306652 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900034 ER PT J AU Wilson, CA Finger, MH Scott, DM AF Wilson, CA Finger, MH Scott, DM TI Recent outbursts from the transient X-ray pulsar Cepheus X-4 (GS 2138+56) SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; stars : neutron; pulsars : individual (GS 2138+56, Cepheus X-4); X-rays : stars ID ACCRETION; STARS; EMISSION; ZONE AB We report on X-ray observations of the 66 s period transient X-ray pulsar Cep X-4 (GS 2138+56) with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory and with the Rossi X-Ray Timing Explorer (RXTE). Two outbursts from Cep X-4 were observed with BATSE in 1993 June-July and in 1997 July. Pulse frequencies of v = 15.0941 +/- 0.0002 mHz on 1993 June 25 (MJD 49,163) and nu = 15.0882 +/- 0.0002 mHz on 1997 July 12 (MJD 50,641) were each measured from %-day spans of BATSE data near each outburst's peak. Cep X-4 showed an average spin down rate of (nu) over dot =(-4.14 +/- 0.08) x 10(-14) Hz s(-1) between the 1993 and 1997 outbursts. After BATSE could no longer detect Cep X-4, public observations were performed on 1997 July 18 and July 25 with the Proportional Counter Array (PCA) on RXTE. A pulse frequency of nu = 15.088 +/- 0.004 mHz was measured from observations on 1997 July 18 (MJD 50,647). Significant aperiodic noise, with an rms variance of similar to 18% in the frequency range 0.01-1.0 Hz, was observed on both days. Energy- and intensity-dependent pulse shape variations were also seen in these data. Recently published optical observations associate Cep X-4 with a Be companion star. If all four outbursts observed from Cep X-4 are assumed to occur at the same orbital phase, we find that the orbital period is between 23 and 147.3 days. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Lab ES84, Huntsville, AL 35812 USA. RP Wilson, CA (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab ES84, Huntsville, AL 35812 USA. NR 25 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 367 EP 373 DI 10.1086/306660 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900036 ER PT J AU Aurass, H Vourlidas, A Andrews, MD Thompson, BJ Howard, RH Mann, G AF Aurass, H Vourlidas, A Andrews, MD Thompson, BJ Howard, RH Mann, G TI Nonthermal radio signatures of coronal disturbances with and without coronal mass ejections SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : activity; Sun : corona; Sun : radio radiation; Sun : UV radiation ID SOLAR-FLARES; TELESCOPE; MISSION AB This study presents data on two events from the Extreme-UV Imaging Telescope (EIT) and the Large Angle and Spectroscopic Coronagraph instruments (C1, C2, and C3), Geostationary Operational Environmental Satellite (GOES) soft X-ray data, and 40-800 MHz radio spectra of the Astrophysical Institute Potsdam. At first glance, the two events appear similar. However, one event decays after a flare-related ejection of cold and hot matter into the lower corona causing only brightness changes in EIT and C1, while the other event marks the onset of a coronal mass ejection (CME) that propagates with a leading-edge speed of approximate to 530 km s(-1) between 2 and 30 R-.. The radio data reveal two differences between the CME and non-CME events: (1) a characteristic faint type III burst group in the time interval with the first clearly CME-related structural change in the coronagraph images and (2) a continuum emission with a frequency drift during the passage of the CME matter through the C1 field of view. Furthermore, we show that the radio spectral data can provide essential information on the timing of the early stages of CME formation and the initial mass motions associated with the ejection. C1 George Mason Univ, Inst Computat Sci & Informat, Ctr Earth Observing & Space Res, Fairfax, VA 22030 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Observ Solare Radioastron, Astrophys Inst Potsdam, D-14482 Potsdam, Germany. RP Aurass, H (reprint author), Observ Solare Radioastron, Astrophys Inst Potsdam, Sternwarte 16, D-14482 Potsdam, Germany. RI Vourlidas, Angelos/C-8231-2009; Thompson, Barbara/C-9429-2012 OI Vourlidas, Angelos/0000-0002-8164-5948; NR 39 TC 22 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP 451 EP 465 DI 10.1086/306653 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NL UT WOS:000079157900045 ER PT J AU Hui, L Stebbins, A Burles, S AF Hui, L Stebbins, A Burles, S TI A geometrical test of the cosmological energy contents using the Ly alpha forest SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : theory; large-scale structure of universe; quasars : absorption lines ID REDSHIFT SPACE; CONSTANT; DISTORTION; UNIVERSE AB We explore a version of the test of cosmological geometry proposed by Alcock & Paczynski in 1979, using observations of the Ly alpha forest in the spectra of close quasar pairs. By comparing the correlations in absorption in one quasar spectrum with correlations between the spectra of neighboring quasars, one can determine the relation of the redshift distance scale to the angle distance scale at the redshift of the absorbers, z similar to 2-4. Since this relationship depends on the parameters of the cosmological model, these parameters may be determined using the Ly alpha forest. While this test is relatively insensitive to the density parameter Omega(m) in a dust-dominated universe, it is more sensitive to the presence of a matter component with large negative pressure (such as a cosmological constant Lambda) and its equation of state. With only 25 pairs of quasar spectra at angular separations 0.'5-2', one can discriminate between an Omega(m) = 0.3 open universe (Lambda = 0) and an Omega(m) = 0.3 flat (Lambda-dominated) universe at the 4 sigma level. C1 Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, POB 500, Batavia, IL 60510 USA. EM lhui@fnal.gov; stebbins@fnal.gov; scott@oddjob.uchicago.edu NR 23 TC 46 Z9 46 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JAN 20 PY 1999 VL 511 IS 1 BP L5 EP L8 DI 10.1086/311826 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NM UT WOS:000079158000002 ER PT J AU Li, SS Guritz, R Logan, T Shindle, M Groves, J Olmsted, C Carsey, F Macmahon, J AF Li, SS Guritz, R Logan, T Shindle, M Groves, J Olmsted, C Carsey, F Macmahon, J TI Summer environmental mapping potential of a large-scale ERS-1 SAR mosaic of the state of Alaska SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article; Proceedings Paper CT 4th Circumpolar Symposium on Remote Sensing of the Polar Environments CY APR 29-MAY 01, 1996 CL TECH UNIV DENMARK, LYNGBY, DENMARK HO TECH UNIV DENMARK ID SYNTHETIC-APERTURE RADAR; SOIL-MOISTURE; MICROWAVE; IMAGERY; FORESTS; FIRES AB One of the largest terrain corrected SAR mosaics, a mosaic of the state of Alaska, was created from 800 ERS-1 SAR summer images. Because of rain events, significant temporal changes of soil moisture often cause substantial changes in the signature of adjacent SAR images acquired on different dates. After an extensive search for suitable images from a large database of the available 1992 and 1993 images, a nearly seamless large-scale digital mosaic of Alaska was successfully generated at a pixel resolution of 100 m. The applications potential of the mosaic are demonstrated by examples in mapping soil moisture, forest fire scars, glaciers, geological, and volcanic features. C1 Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Stanford Univ, Stanford, CA 94305 USA. RP Li, SS (reprint author), Univ Alaska, Inst Geophys, POB 757320, Fairbanks, AK 99775 USA. NR 32 TC 6 Z9 6 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JAN 20 PY 1999 VL 20 IS 2 BP 387 EP 401 DI 10.1080/014311699213505 PG 15 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 167YF UT WOS:000078661900011 ER PT J AU Carpenter, MH Nordstrom, J Gottlieb, D AF Carpenter, MH Nordstrom, J Gottlieb, D TI A stable and conservative interface treatment of arbitrary spatial accuracy SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE high-order finite-difference; numerical stability; interface conditions; summation-by-parts ID MULTIDOMAIN SPECTRAL SOLUTION; NAVIER-STOKES EQUATIONS; DIFFERENCE APPROXIMATIONS; PENALTY METHOD; SUMMATION; PARTS; PROJECTIONS; STABILITY; FLOWS AB Stable and accurate interface conditions based on the SAT penalty method are derived for the linear advection-diffusion equation. The conditions are functionally independent of the spatial order of accuracy and rely only on the form of the discrete operator. We focus on high-order finite-difference operators that satisfy the summation-by-parts (SBP) property. We prove that stability is a natural consequence of the SEP operators used in conjunction with the new, penalty type, boundary conditions. In addition, we show that the interface treatments are conservative. The issue of the order of accuracy of the interface boundary conditions is clarified. New finite-difference operators of spatial accuracy up to sixth order are constructed which satisfy the SEP property. These finite-difference operators are shown to admit design accuracy (pth-order global accuracy) when (p - 1)th-order stencil closures an used near the boundaries, if the physical boundary conditions and interface conditions are implemented to at least pth-order accuracy. Stability and accuracy are demonstrated on the nonlinear Burgers' equation for a 12-subdomain problem with randomly distributed interfaces. (C) 1999 Academic Press. C1 NASA, Langley Res Ctr, Aerodynam & Acoust Methods Branch, Hampton, VA 23681 USA. Aeronaut Res Inst Sweden, FFA, Computat Aerodynam Dept, Bromma, Sweden. Brown Univ, Div Appl Math, Providence, RI 02912 USA. RP Carpenter, MH (reprint author), NASA, Langley Res Ctr, Aerodynam & Acoust Methods Branch, Hampton, VA 23681 USA. OI Nordstrom, Jan/0000-0002-7972-6183 NR 17 TC 170 Z9 170 U1 1 U2 4 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JAN 20 PY 1999 VL 148 IS 2 BP 341 EP 365 DI 10.1006/jcph.1998.6114 PG 25 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 158UA UT WOS:000078134300003 ER PT J AU Nordstrom, J Carpenter, MH AF Nordstrom, J Carpenter, MH TI Boundary and interface conditions for high-order finite-difference methods applied to the Euler and Navier-Stokes equations SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID SUMMATION; PARTS; APPROXIMATIONS; CONVERGENCE; PROJECTIONS; STABILITY AB Boundary and interface conditions for high-order finite difference methods applied to the constant coefficient Euler and Navier-Stokes equations are derived. The boundary conditions lead to strict and strong stability. The interface conditions are stable and conservative even if the finite difference operators and mesh sizes vary from domain to domain. Numerical experiments show that the new conditions also lead to good results for the corresponding nonlinear problems. (C) 1999 Academic Press. C1 Aeronaut Res Inst Sweden, FFA, Bromma, Sweden. Univ Uppsala, Dept Comp Sci, Uppsala, Sweden. NASA, Langley Res Ctr, Aerodynam & Acoust Methods Branch, Hampton, VA 23681 USA. RP Nordstrom, J (reprint author), Aeronaut Res Inst Sweden, FFA, Bromma, Sweden. OI Nordstrom, Jan/0000-0002-7972-6183 NR 34 TC 63 Z9 63 U1 0 U2 2 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JAN 20 PY 1999 VL 148 IS 2 BP 621 EP 645 DI 10.1006/jcph.1998.6133 PG 25 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 158UA UT WOS:000078134300014 ER PT J AU Roelle, P Aneja, VP O'Connor, J Robarge, W Kim, DS Levine, JS AF Roelle, P Aneja, VP O'Connor, J Robarge, W Kim, DS Levine, JS TI Measurement of nitrogen oxide emissions from an agricultural soil with a dynamic chamber system SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SOUTHEAST UNITED-STATES; NITRIC-OXIDE; FIELD-MEASUREMENTS; NOX EMISSIONS; TROPICAL FOREST; SAVANNA SOILS; FLUXES; ECOSYSTEMS; SITE; N2O AB Biogenic soil emissions of nitric oxide (NO) were measured from an intensively managed agricultural row crop (corn, Zea mays) during a 4 week period (May 15 through June 9, 1995). The site was located in Washington County, near the town of Plymouth, which is in the Lower Coastal Plain of North Carolina. Soil NO flux was determined using a dynamic flow-through chamber technique. The measurement period was characterized by two distinguishing features: an application of nitrogen (N) fertilizer at the midpoint of the experiment and a nontypical rainfall pattern. Average NO flux prior to the application of N fertilizer was 31.5 +/- 10.1 np N m(-2) s(-1), and more than doubled (77.7 +/- 63.7 ng N m(-2) s(-1)) after the application of a side-dressing of N fertilizer. Average soil extractable nitrogen values did not change significantly following application of the side-dressing of N fertilizer. We attribute this failure to detect a significant difference in soil extractable nitrogen following N fertilization to the method in which the fertilizer was applied, the subsequent rainfall pattern, and the technique of soil sampling. NO flux followed the same diurnal trend as soil temperature, with maximum NO emissions coinciding with maximum soil temperature, and minimum NO emissions coinciding with minimum soil temperature. NO flux was found to increase exponentially with soil temperature, but only after fertilization. Due to subsurface irrigation practices employed by the farmer, changes in soil water content were minimal, and no relation could be drawn between soil water content and NO flux. Simultaneous measurements of NOy, NO2, and NO emissions revealed that NO and NO2 emissions represent 86 and 8.7%, respectively, of NOy emissions leaving the soil. Simultaneous NO flux measurements made by a closed box flux technique, at the same site, revealed no statistically significant differences between the two different methodologies for measuring NO flux. C1 N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Raleigh, NC 27695 USA. N Carolina State Univ, Dept Soil Sci, Raleigh, NC 27695 USA. Kunsan Natl Univ, Dept Environm Engn, Kunsan 573701, South Korea. NASA, Div Atmospher Sci, Langley Res Ctr, Hampton, VA 23681 USA. RP Roelle, P (reprint author), N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Box 8208, Raleigh, NC 27695 USA. EM VINEY_ANEJA@NCSU.edu NR 48 TC 23 Z9 24 U1 1 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 20 PY 1999 VL 104 IS D1 BP 1609 EP 1619 DI 10.1029/98JD01202 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 159RU UT WOS:000078188700003 ER PT J AU Fioletov, VE Kerr, JB Hare, EW Labow, GJ McPeters, RD AF Fioletov, VE Kerr, JB Hare, EW Labow, GJ McPeters, RD TI An assessment of the world ground-based total ozone network performance from the comparison with satellite data SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DOBSON NETWORK; NIMBUS-7 TOMS; SPECTROPHOTOMETER; QUALITY AB Total ozone data available from the World Ozone and Ultraviolet Radiation Data Centre (WOUDC) have been compared with Version 7 of the Nimbus 7 (for the 1978-1993 period) and Meteor 3 total ozone mapping spectrometer (TOMS) data sets (for the 1991-1994 period) and with Version 6 of the Nimbus 7 solar backscattered ultraviolet (SBUV) data set (for the 1978-1990 period). Comparison between the ground-based and satellite observations resulted in parameters such as bias, scattering, relative trend, and seasonal component. About 80% of all Dobson, Brewer, and filter ozonometer stations have standard deviations of monthly mean differences with TOMS that are less than 2.5%. Typically, results of the comparisons between ground-based stations and SBUV are similar to those for ground-based and TOMS comparisons. For the ground-based direct sun total ozone measurements the standard deviations between TOMS and Dobson daily mean values are about 2.4%. The standard deviations for Brewer and filter ozonometer stations are 2.2 and 3.5%, respectively. For the less accurate zenith sky measurements, standard deviations are 3.8% for Dobsons, 4% for Brewers, and 4.7% for filter ozonometer data. Comparisons of individual ground-based measurements with satellite overpasses yield standard deviations which for middle latitudes increase approximately linearly from about 2% at coincidence to 6% for a 24 hour difference in time or a 600 km spatial difference. Typical problems with ground-based observations and results of the comparisons for individual stations are also discussed. C1 Environm Canada, N York, ON M3H 5T4, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon STX Corp, Greenbelt, MD 20770 USA. RP Fioletov, VE (reprint author), Environm Canada, 4905 Dufferin St, N York, ON M3H 5T4, Canada. EM Vitali.Fioletov@ec.gc.ca RI McPeters, Richard/G-4955-2013; OI McPeters, Richard/0000-0002-8926-8462; Fioletov, Vitali/0000-0002-2731-5956 NR 39 TC 50 Z9 55 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 20 PY 1999 VL 104 IS D1 BP 1737 EP 1747 DI 10.1029/1998JD100046 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 159RU UT WOS:000078188700014 ER PT J AU Considine, DB Stolarski, RS Hollandsworth, SM Jackman, CH Fleming, EL AF Considine, DB Stolarski, RS Hollandsworth, SM Jackman, CH Fleming, EL TI A Monte Carlo uncertainty analysis of ozone trend predictions in a two-dimensional model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CHLORINE PERTURBATIONS; SENSITIVITY; IMPRECISIONS; PROPAGATION; DEPLETION; RATIO AB We use Monte Carlo analysis to estimate the uncertainty in predictions of total O-3 trends between 1979 and 1995 made by the Goddard Space Flight Center (GSFC) two-dimensional (2-D) model of stratospheric photochemistry and dynamics. The uncertainty is caused by gas phase chemical reaction rates, photolysis coefficients, and heterogeneous reaction parameters which are model inputs. The uncertainty represents a lower bound to the total model uncertainty assuming the input parameter uncertainties are characterized correctly. Each of the Monte Carlo runs was initialized in 1970 and integrated for 26 model years through the end of 1995. This was repeated 419 times using input parameter sets generated by Latin hypercube sampling. The standard deviation (sigma) of the Monte Carlo ensemble of total O-3 trend predictions is used to quantify the model uncertainty. The 34% difference between the model trend in globally and annually averaged total O-3 using nominal inputs and atmospheric trends calculated from Nimbus 7 and Meteor 3 total ozone mapping spectrometer (TOMS) version 7 data is less than the 46% calculated la model uncertainty, so there is no significant difference between the modeled and observed trends. In the northern hemisphere midlatitude spring the modeled and observed total O-3 trends differ by more than la but less than 2 sigma, which we refer to as marginal significance. We perform a multiple linear regression analysis of the runs which suggests that only a few of the model reactions contribute significantly to the variance in the model predictions. The lack of significance in these comparisons suggests that they are of questionable use as guides for continuing model development. Large model/measurement differences which are many multiples of the input parameter uncertainty are seen in the meridional gradients of the trend and the peak-to-peak variations in the trends over an annual cycle. These discrepancies unambiguously indicate model formulation problems and provide a measure of model performance which can be used in attempts to improve such models. C1 Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Steven Myers & Associates Corp, Vienna, VA USA. RP Considine, DB (reprint author), Univ Maryland, Dept Meteorol, 3439 Comp & Space Sci Bldg, College Pk, MD 20742 USA. EM dbc@welkin.gsfc.nasa.gov RI Stolarski, Richard/B-8499-2013; Jackman, Charles/D-4699-2012 OI Stolarski, Richard/0000-0001-8722-4012; NR 24 TC 13 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 20 PY 1999 VL 104 IS D1 BP 1749 EP 1765 DI 10.1029/1998JD100028 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 159RU UT WOS:000078188700015 ER PT J AU Rinsland, CP Salawitch, RJ Gunson, MR Solomon, S Zander, R Mahieu, E Goldman, A Newchurch, MJ Irion, FW Chang, AY AF Rinsland, CP Salawitch, RJ Gunson, MR Solomon, S Zander, R Mahieu, E Goldman, A Newchurch, MJ Irion, FW Chang, AY TI Polar stratospheric descent of NOy and CO and Arctic denitrification during winter 1992-1993 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TOTAL REACTIVE NITROGEN; SOLAR OCCULTATION SPECTRA; MIDDLE ATMOSPHERE; ANTARCTIC STRATOSPHERE; 2-DIMENSIONAL MODEL; APRIL 1993; CARBON-MONOXIDE; NOVEMBER 1994; NITRIC-OXIDE; VORTEX AIR AB Observations inside the November 1994 Antarctic stratospheric vortex and inside the April 1993 remnant Arctic stratospheric vortex by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer are reported. In both instances, elevated volume mixing ratios (VMRs) of carbon monoxide (CO) were measured. A peak Antarctic CO VMR of 60 ppbv (where 1 ppbv = 10(-9) per unit volume) was measured at a potential temperature (Theta) of 710 K (similar to 27 km), about 1 km below the altitude of a pocket of elevated NOy (total reactive nitrogen) at a deep minimum in N2O (<5 ppbv). The Arctic observations also show a region of elevated vortex CO with a peak VMR of 90 ppbv at 630-670 K (similar to 25 km) but no corresponding enhancement in NOy, perhaps because of stronger dynamical activity in the northern hemisphere polar winter and/or interannual variability in the production of mesospheric NO. By comparing vortex and extravortex observations of NOy obtained at the same N2O VMR, Arctic vortex denitrification of 5 +/- 2 ppbv at 470 K (similar to 18 km) is inferred. We show that our conclusion of substantial Arctic winter 1992-1993 denitrification is robust by comparing our extravortex observations with previous polar measurements obtained over a wide range of winter conditions. Correlations of NOy with N2O measured at the same Theta by ATMOS in the Arctic vortex and at midlatitudes on board the ER-2 aircraft several weeks later lie along the same mixing line. The result demonstrates the consistency of the two data sets and confirms that the ER-2 sampled fragments of the denitrified Arctic vortex following its breakup, An analysis of the ATMOS Arctic measurements of total hydrogen shows no evidence for significant dehydration inside the vortex. C1 NASA, Div Atmospher Sci, Langley Res Ctr, Hampton, VA 23681 USA. NOAA, Aeron Lab, Boulder, CO 80303 USA. Univ Alabama, Dept Atmospher Sci, Huntsville, AL 35899 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Denver, Dept Phys, Denver, CO 80208 USA. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. RP Rinsland, CP (reprint author), NASA, Div Atmospher Sci, Langley Res Ctr, Hampton, VA 23681 USA. RI Salawitch, Ross/B-4605-2009 OI Salawitch, Ross/0000-0001-8597-5832 NR 61 TC 33 Z9 33 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JAN 20 PY 1999 VL 104 IS D1 BP 1847 EP 1861 DI 10.1029/1998JD100034 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 159RU UT WOS:000078188700022 ER PT J AU Huang, J Feria, A AF Huang, J Feria, A TI A 1-m X-band inflatable reflectarray antenna SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE inflatable antenna; microstrip reflectarray; X-band ID MICROSTRIP AB A 1-m, X-band, circularly polarized, inflatable microstrip reflectarray has been developed. It has demonstrated the achievement of a surface tolerance of +/- 1.3 mm, a mass of 1.2 kg, a bandwidth of at least 3%, a peak sidelobe and a peak cross-pol of -18 dB, and a radiation efficiency of 37%. Correctable areas have been identified to improve the radiation efficiency in the future. (C) 1999 John Wiley & Sons, Inc. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Huang, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 8 Z9 8 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD JAN 20 PY 1999 VL 20 IS 2 BP 97 EP 99 DI 10.1002/(SICI)1098-2760(19990120)20:2<97::AID-MOP4>3.0.CO;2-K PG 3 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA 152KP UT WOS:000077776800004 ER PT J AU Roberts, DA Goldstein, ML Deane, AE Ghosh, S AF Roberts, DA Goldstein, ML Deane, AE Ghosh, S TI Quasi-two-dimensional MHD turbulence in three-dimensional flows SO PHYSICAL REVIEW LETTERS LA English DT Article ID FLUX-CORRECTED TRANSPORT; SOLAR-WIND FLUCTUATIONS; MAGNETOHYDRODYNAMIC TURBULENCE AB We simulate how nearly two-dimensional magnetohydrodynamic turbulence can be initiated and how it evolves with distance in the third dimension. Expanding flows lead to a suppression of the nonlinear cascades, mainly due to the changing transverse length scales. Velocity fluctuation levels are determined more from the 2D dynamics than from the expansion except when the velocity fluctuations are initially dominant. With expansion, magnetic fluctuations always dominate velocity fluctuations at late times. [S0031-9007(98)08244-1]. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. Space Applicat Corp, Vienna, VA USA. RP NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RI Goldstein, Melvyn/B-1724-2008 NR 17 TC 12 Z9 12 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 EI 1079-7114 J9 PHYS REV LETT JI Phys. Rev. Lett. PD JAN 18 PY 1999 VL 82 IS 3 BP 548 EP 551 DI 10.1103/PhysRevLett.82.548 PG 4 WC Physics, Multidisciplinary SC Physics GA 157KC UT WOS:000078059200022 ER PT J AU Long, M Crooks, R Rack, HJ AF Long, M Crooks, R Rack, HJ TI High-cycle fatigue performance of solution-treated metastable-beta titanium alloys SO ACTA MATERIALIA LA English DT Article ID ORIENTATION IMAGING MICROSCOPY; MECHANICAL-PROPERTIES; CRACK INITIATION; MEDICAL IMPLANTS; FRACTURE; ELEMENTS AB The effect of grain boundary misorientation on the high-cycle fatigue performance of solution-treated, metastable-beta titanium alloys was investigated. Initial damage during cyclic deformation was associated with the formation of coarse, planar slip bands, these often propagating through several grains without obstruction or redirection when intersecting with a grain boundary. This "continuous" slip through several grains was associated with the presence of a significant number of "low-angle" grain boundaries. Fatigue crack initiation was associated with crack initiation at intersecting planar slip bands at the free surface. The increase in operative slip length occasioned by the presence of low-angle grain boundaries lead to enhanced crack initiation and reduced lifetime. Fatigue crack propagation was characterized by step-like features formed through the interaction of the propagating crack and the coarse slip bands present in the plastic zone ahead of the crack tip. The direction of local fatigue crack propagation was also minimally affected when crossing low-angle grain boundaries. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved. C1 Clemson Univ, Sch Chem & Mat Engn, Clemson, SC 29634 USA. NASA, Langley Res Ctr, Analyt Serv & Mat Inc, Hampton, VA 23681 USA. RP Rack, HJ (reprint author), Clemson Univ, Sch Chem & Mat Engn, Clemson, SC 29634 USA. NR 31 TC 19 Z9 20 U1 0 U2 11 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1359-6454 J9 ACTA MATER JI Acta Mater. PD JAN 15 PY 1999 VL 47 IS 2 BP 661 EP 669 DI 10.1016/S1359-6454(98)00343-7 PG 9 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 164RF UT WOS:000078476800025 ER PT J AU De Stasio, G Gilbert, B Perfetti, L Hansen, R Mercanti, D Ciotti, MT Andres, R White, VE Perfetti, P Margaritondo, G AF De Stasio, G Gilbert, B Perfetti, L Hansen, R Mercanti, D Ciotti, MT Andres, R White, VE Perfetti, P Margaritondo, G TI Cell ashing for trace element analysis: A new approach based on ultraviolet/ozone SO ANALYTICAL BIOCHEMISTRY LA English DT Article DE synchrotron spectromicroscopy; microchemical analysis; MEPHISTO; ashing; incineration; trace element ID NEURONS; SPECTROMICROSCOPY; CULTURES; SURFACES AB We studied a new approach to cell ashing based on illuminating the specimens with a low-pressure mercury discharge lamp. We analyzed with synchrotron spectromicroscopy its effects on different physiological elements in neurobiological specimens. Our results demonstrate that carbon is removed, whereas phosphorus, calcium, potassium, and sulfur are retained and their relative concentrations are enhanced. Applied to trace elements, this technique will enhance their practical detectability. (C) 1999 Academic Press. C1 CNR, Ist Struttura Mat, I-00133 Rome, Italy. Ecole Polytech Fed Lausanne, Inst Phys Appl, PH Ecublens, CH-1015 Lausanne, Switzerland. Univ Roma Tor Vergata, Rome, Italy. Univ Wisconsin, Ctr Synchrotron Radiat, Stoughton, WI 53589 USA. CNR, Ist Neurobiol, I-00137 Rome, Italy. Paul Scherrer Inst, CH-5232 Villigen, Switzerland. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Sincrotrone Trieste SCpA, Trieste, Italy. RP De Stasio, G (reprint author), CNR, Ist Struttura Mat, Via Fosso Cavaliere, I-00133 Rome, Italy. RI Margaritondo, Giorgio/B-1367-2008; Gilbert, Benjamin/E-3182-2010; Gilbert, Pupa/A-6299-2010; OI Gilbert, Pupa/0000-0002-0139-2099; Mercanti, Delio/0000-0001-8301-2098 NR 17 TC 11 Z9 11 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0003-2697 J9 ANAL BIOCHEM JI Anal. Biochem. PD JAN 15 PY 1999 VL 266 IS 2 BP 174 EP 180 DI 10.1006/abio.1998.2901 PG 7 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Chemistry, Analytical SC Biochemistry & Molecular Biology; Chemistry GA 162LY UT WOS:000078349400002 PM 9888973 ER PT J AU Mason, GM Cohen, CMS Cummings, AC Dwyer, JR Gold, RE Krimigis, SM Leske, RA Mazur, JE Mewaldt, RA Mobius, E Popecki, M Stone, EC von Rosenvinge, TT Wiedenbeck, ME AF Mason, GM Cohen, CMS Cummings, AC Dwyer, JR Gold, RE Krimigis, SM Leske, RA Mazur, JE Mewaldt, RA Mobius, E Popecki, M Stone, EC von Rosenvinge, TT Wiedenbeck, ME TI Particle acceleration and sources in the November 1997 solar energetic particle events SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SHOCK ACCELERATION; ABUNDANCES; INJECTION; TRANSPORT; PROTONS; WIND AB We report studies of two large solar energetic particle (SEP) events on Nov. 4 and 6, 1997 that were observed using advanced energetic particle detectors on the ACE and the Wind spacecraft. Both events showed enriched Fe/O, and had a similar to 1 MeV/n (3)He/(4)He ratio = 2.1 x 10(-3), 4 times the coronal value. The Nov. 6 event had exceptionally hard spectra, with much higher intensities of high energy (10s of MeV) particles than the Nov. 4 event, yet below 1 MeV/n the intensities in the Nov. 6 event were lower than for Nov. 4. Strong, complex temporal variations observed for similar to 120 keV Fe/O contrasted with only gradual changes of this ratio at similar to 25 MeV/n. A spectral break was observed in the Nov. 6 event, wherein below a few MeV/n the spectra became harder. Taken together, these observations point to different seed and acceleration mechanisms dominating at low and high energies in these events. C1 Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. CALTECH, Pasadena, CA 91125 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. Aerosp Corp, Los Angeles, CA 90009 USA. Univ New Hampshire, Durham, NH 03824 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Mason, GM (reprint author), Univ Maryland, Dept Phys, College Pk, MD 20742 USA. EM mason@sampx3.umd.edu OI Moebius, Eberhard/0000-0002-2745-6978 NR 18 TC 69 Z9 69 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JAN 15 PY 1999 VL 26 IS 2 BP 141 EP 144 DI 10.1029/1998GL900235 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 160JE UT WOS:000078226200001 ER PT J AU Cohen, CMS Cummings, AC Leske, RA Mewaldt, RA Stone, EC Dougherty, BL Wiedenbeck, ME Christian, ER von Rosenvinge, TT AF Cohen, CMS Cummings, AC Leske, RA Mewaldt, RA Stone, EC Dougherty, BL Wiedenbeck, ME Christian, ER von Rosenvinge, TT TI Inferred charge states of high energy solar particles from the Solar Isotope Spectrometer on ACE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MEAN IONIC CHARGE; ABUNDANCES; NUCLEON; FLARES AB The large solar event on November 6, 1997, was enriched in heavy elements (Fe/O similar to 1) with very hard energy spectra (power law index of -2). There was also a large enrichment in heavier isotopes, suggesting unusually strong charge to mass (Q/M) fractionation (similar to(Q/M)(-7)). Assuming that the fractionation is dominated by Q/M and first ionization potential (FIP) related processes, we have inferred the charge states of twelve elements with energies of 12-60 MeV/nucleon. These results suggest a source temperature of 3 - 6 x 10(6) K, significantly higher than deduced at lower energies. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Cohen, CMS (reprint author), CALTECH, MC 220-47, Pasadena, CA 91125 USA. RI Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 24 TC 58 Z9 58 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JAN 15 PY 1999 VL 26 IS 2 BP 149 EP 152 DI 10.1029/1998GL900218 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 160JE UT WOS:000078226200003 ER PT J AU Leske, RA Cohen, CMS Cummings, AC Mewaldt, RA Stone, EC Dougherty, BL Wiedenbeck, ME Christian, ER von Rosenvinge, TT AF Leske, RA Cohen, CMS Cummings, AC Mewaldt, RA Stone, EC Dougherty, BL Wiedenbeck, ME Christian, ER von Rosenvinge, TT TI Unusual isotopic composition of solar energetic particles observed in the November 6, 1997 event SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ABUNDANCES; FLARES; NUCLEI; NEON AB Using the Solar Isotope Spectrometer on the Advanced Composition Explorer, we have measured the isotopic composition of solar energetic particles (SEPs) with energies of tens of MeV/nucleon during the November 6, 1997 solar event, including isotopes never before reported in SEPs, such as S-34, Ar-38, Ca-44, Fe-54, and Ni-60, as well as isotopes of C, N, O, Ne, Mg, and Si. Abundances are found to be enhanced,by factors of similar to 2 relative to the standard solar system values for Ne-22/Ne-20 and Mg-26/Mg-24. Overall, the enrichments of the isotope ratios show a correlation with the ratio of masses, M-2/M-1, scaling approximately as (M-2/M-1)(7), although significant deviations from this trend are evident. C1 CALTECH, Space Radiat Lab, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Leske, RA (reprint author), CALTECH, Space Radiat Lab, Mail Code 220-47, Pasadena, CA 91125 USA. RI Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 21 TC 19 Z9 19 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JAN 15 PY 1999 VL 26 IS 2 BP 153 EP 156 DI 10.1029/1998GL900173 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 160JE UT WOS:000078226200004 ER PT J AU Skoug, RM Bame, SJ Feldman, WC Gosling, JT McComas, DJ Steinberg, JT Tokar, RL Riley, P Burlaga, LF Ness, NF Smith, CW AF Skoug, RM Bame, SJ Feldman, WC Gosling, JT McComas, DJ Steinberg, JT Tokar, RL Riley, P Burlaga, LF Ness, NF Smith, CW TI A prolonged He+ enhancement within a coronal mass ejection in the solar wind SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETIC TOPOLOGY AB A coronal mass ejection and magnetic cloud containing an unusually large enhancement of He+ was observed in the solar wind by the plasma and magnetic field instruments on the Advanced Composition Explorer (ACE) spacecraft on May 2-4, 1998. The He+/He++ ratio during this event exceeded 0.5% for a period of more than 24 hours, and reached values as high as 100%. The high He+/He++ ratio indicates the presence of prominence material, and in fact a disappearing filament and prominence were observed at the Sun in association with this event. The prolonged observation of He+ indicates that prominence material extended through much of this CME, the first such observation in a CME in the solar wind. C1 Los Alamos Natl Lab, Los Alamos, NM 87545 USA. SciberNet Inc, San Diego, CA 92121 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RP Skoug, RM (reprint author), Los Alamos Natl Lab, MS D466, Los Alamos, NM 87545 USA. EM rskoug@lanl.gov NR 16 TC 70 Z9 71 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JAN 15 PY 1999 VL 26 IS 2 BP 161 EP 164 DI 10.1029/1998GL900207 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 160JE UT WOS:000078226200006 ER PT J AU Haggerty, DK Desai, MI Mason, GM Dwyer, JR Gold, RE Krimigis, SM Mazur, JE von Rosenvinge, TT AF Haggerty, DK Desai, MI Mason, GM Dwyer, JR Gold, RE Krimigis, SM Mazur, JE von Rosenvinge, TT TI Simultaneous observations of energetic (similar to 150 keV) protons upstream of the Earth's bow shock at ACE and WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID IONS OBSERVED UPSTREAM; EVENTS AB We report measurements of similar to 150 keV proton intensity enhancements obtained at ACE and WIND when both spacecraft were upstream of the Earth's bow shock. We investigate differences in the onset times, the duration's, and the local magnetic field orientations for 4 events observed simultaneously at the two spacecraft. A simple statistical analysis shows only 2% of the simultaneous events could be random coincidences, which indicates that out of the 20 events observed at each spacecraft, the 4 simultaneous measurements are probably observations of the same events. Since these measurements were obtained when the two spacecraft were separated by distances >25 R-E these particles probably originate from a source region that possibly covers the scale size of the Earth's bow shock (similar to 10 R-E), and this is substantially larger than the smaller source regions proposed by existing models. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. Aerospace Corp, Los Angeles, CA 90009 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Haggerty, DK (reprint author), Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA. NR 13 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JAN 15 PY 1999 VL 26 IS 2 BP 169 EP 172 DI 10.1029/1998GL900288 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 160JE UT WOS:000078226200008 ER PT J AU Chandra, S Ziemke, JR Stewart, RW AF Chandra, S Ziemke, JR Stewart, RW TI An 11-year solar cycle in tropospheric ozone from TOMS measurements SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID COLUMN OZONE; LONG-TERM; CLIMATE; MODEL; PHOTODISSOCIATION; VARIABILITY; ATMOSPHERE; CHEMISTRY; DYNAMICS; RADICALS AB Tropospheric column ozone derived from Nimbus 7 total ozone mapping spectrometer (TOMS) footprint measurements from 1979 to 1992 provide the first observational evidence of changes in tropospheric ozone in the marine atmosphere of the tropics which are out of phase with the stratospheric ozone changes on a time scale of a solar cycle. The estimated changes in tropospheric and stratospheric column ozone over a solar cycle are respectively -2.98 +/- 1.31 and +8.63 +/- 1.99 Dobson units (DU) or -12.6 +/- 5.6 and +3.69 +/- 0.86 % from solar minimum to solar maximum. These values are statistically significant at the 2 sigma level. In comparison, linear trends in tropical tropospheric ozone are not statistically significant. These observations are qualitatively consistent with a modulation effect on tropospheric ozone photochemistry by W-induced changes ih stratospheric ozone. However, in the low NOx regime of the marine atmosphere, the observed changes are significantly larger than estimated from a photochemical model. Explanation for the solar signal may include subtle solar-induced changes in transport in the troposphere involving law boundary-layer ozone and ozone precursors. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Software Corp Amer, Beltsville, MD 20705 USA. RP Chandra, S (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. NR 25 TC 37 Z9 40 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JAN 15 PY 1999 VL 26 IS 2 BP 185 EP 188 DI 10.1029/1998GL900272 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 160JE UT WOS:000078226200012 ER PT J AU Loh, CY Liou, MS Hui, WH AF Loh, CY Liou, MS Hui, WH TI An investigation of random choice method for three-dimensional steady supersonic flows SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE random choice; Lagrangian; 3D supersonic flow ID 2-DIMENSIONAL GAS-DYNAMICS; CONSERVATION-LAWS; DIFFERENCE-SCHEMES; RIEMANN PROBLEM; HYPERBOLIC SYSTEMS; NUMERICAL-SOLUTION; LAGRANGIAN METHOD; SPACE DIMENSIONS; EQUATIONS; GODUNOV AB In this paper, an unsplit random choice method (RCM) is developed and applied to numerically solve three-dimensional supersonic steady flow problems. In order to keep the contacts (slip surfaces) crisply resolved, a new Lagrangian formulation is employed. Due to the lack of exact solutions to 3D Riemann problems, approximate Riemann solutions in the weak sense are adopted. The RCM is thus as efficient as the deterministic TVD schemes, and yields almost identical results in the model problems. Copyright (C) 1999 John Wiley & Sons, Ltd. C1 NASA, Lewis Res Ctr, Internal Fluid Mech Div, Cleveland, OH 44135 USA. Hong Kong Univ Sci & Technol, Dept Math, Hong Kong, Peoples R China. RP Loh, CY (reprint author), NASA, Lewis Res Ctr, Internal Fluid Mech Div, Mail Stop 5-11, Cleveland, OH 44135 USA. NR 32 TC 3 Z9 3 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD JAN 15 PY 1999 VL 29 IS 1 BP 97 EP 119 DI 10.1002/(SICI)1097-0363(19990115)29:1<97::AID-FLD780>3.0.CO;2-J PG 23 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA 158PL UT WOS:000078123900006 ER PT J AU Leonard, CL McClain, CR Murtugudde, R Hofmann, EE Harding, LW AF Leonard, CL McClain, CR Murtugudde, R Hofmann, EE Harding, LW TI An iron-based ecosystem model of the central equatorial Pacific SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID PHYTOPLANKTON GROWTH; SOLAR IRRADIANCE; TROPICAL OCEANS; MIXED-LAYER; CARBON; SEA; 140-DEGREES-W; TEMPERATURE; LIMITATION; SIMULATION AB The central and eastern equatorial Pacific region is characterized by lower than expected phytoplankton biomass and primary production given the relatively high ambient nitrate concentrations. These unusual conditions have spawned several field programs and laboratory experiments to determine why this high nitrate-low chlorophyll pattern persists in this region. To synthesize the results from these field programs, as well as providing additional evidence in support of the iron hypothesis, we developed a one-dimensional, nine-component ecosystem model of 0 degrees N 140 degrees W. The model components include two phytoplankton size fractions, two zooplankton size fractions, two detrital size fractions, dissolved iron, nitrate, and ammonium. The model was run for 5 years (1990-1994) and was forced using an atmospheric radiative transfer model, an ocean general circulation model (GCM), and in situ data. To our knowledge, this is the first ecosystem model at 0 degrees N 140 degrees W to synthesize the Joint Global Ocean Flux Study Equatorial Pacific Process Study (JGOFS EqPac) data set, as well as to use both in situ and modeled physical data to drive the model. Modeled phytoplankton, zooplankton, and iron all varied on interannual timescales due to El Nino events. Total phytoplankton biomass increased by as much as 40% from early 1992 (El Nino warm) to 1993 (normal). The results also indicate that the biomass increase during a cool period is not constant for each phytoplankton component, but instead the increase is most evident in the netphytoplankton (>10 mu m). Netphytoplankton increase from a low of 0.1% of the total chlorophyll in 1992 to a high of 30% of the total in 1993. Microzooplankton grazing rates fluctuated in response to changes in nanophytoplankton growth rates, whereas mesozooplankton grazing was unrelated to netphytoplankton growth rates. The magnitude and temporal variability of phytoplankton chlorophyll agreed well with in situ data collected during 1992. Modeled primary production was lower than measured during El Nino but agreed with observations during normal conditions. The low primary productivity was probably a result of downwelling produced by the physical model. New production was calculated from total and recycled iron rather than nitrate-based production and was more variable in general and almost 3 times the nitrate-based new production during non-El Nino conditions. C1 Univ Maryland, Marine Estuarine Environm Sci Program, College Pk, MD USA. NASA, WiFS Project Off, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Joint Ctr Earth Syst Sci, College Pk, MD 20742 USA. Old Dominion Univ, Ctr Coastal Phys Oceanog, Norfolk, VA 23529 USA. Univ Maryland, Horn Point Lab, Ctr Environm Sci, Cambridge, MD USA. Univ Maryland, Maryland Sea Grant Coll, College Pk, MD 20742 USA. RP Leonard, CL (reprint author), Univ Hawaii, Joint Inst Marine & Atmospher Res, Honolulu, HI 96822 USA. NR 57 TC 63 Z9 64 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JAN 15 PY 1999 VL 104 IS C1 BP 1325 EP 1341 DI 10.1029/1998JC900049 PG 17 WC Oceanography SC Oceanography GA 158LE UT WOS:000078116300008 ER PT J AU Brydon, D Sun, S Bleck, R AF Brydon, D Sun, S Bleck, R TI A new approximation of the equation of state for seawater, suitable for numerical ocean models SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article AB An approximation to the UNESCO equation of state for seawater is obtained in the form of a polynomial that is cubic in potential temperature, quadratic in pressure, and linear in salinity. The polynomial represents a reasonable compromise between accuracy and computational economy; it also allows potential temperature to be obtained analytically from given values of density, salinity, and pressure. C1 Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 USA. RP Brydon, D (reprint author), Univ Calif Los Alamos Natl Lab, POB 1663, Los Alamos, NM 87545 USA. RI Sun, Shan/H-2318-2015 NR 9 TC 42 Z9 45 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JAN 15 PY 1999 VL 104 IS C1 BP 1537 EP 1540 DI 10.1029/1998JC900059 PG 4 WC Oceanography SC Oceanography GA 158LE UT WOS:000078116300021 ER PT J AU Lambert, JC Van Roozendael, M De Maziere, M Simon, PC Pommereau, JP Goutail, F Sarkissian, A Gleason, JF AF Lambert, JC Van Roozendael, M De Maziere, M Simon, PC Pommereau, JP Goutail, F Sarkissian, A Gleason, JF TI Investigation of pole-to-pole performances of spaceborne atmospheric chemistry sensors with the NDSC SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article; Proceedings Paper CT Conference on Global Measurement Systems for Atmospheric Composition CY MAY, 1997 CL TORONTO, CANADA SP Int Global Atmospher Chem Program, Stratospher Proc & Their Role Climate, Global Atmospher Watch, Canadian Space Agcy, Atmospher Environm Serv ID HALOGEN OCCULTATION EXPERIMENT; ABSORPTION CROSS-SECTIONS; TOTAL OZONE DATA; RADIATIVE-TRANSFER MODELS; GROUND-BASED MEASUREMENTS; ZENITH-SKY SPECTROMETERS; AIR-MASS FACTORS; TEMPERATURE-MEASUREMENTS; BACKSCATTER ULTRAVIOLET; VISIBLE MEASUREMENTS AB Spaceborne atmospheric chemistry sensors provide unique access to the distribution and variation of the concentration of many trace species on the global scale. However. since the measurements and the retrieval algorithms are sensitive to a variety of instrumental as well as atmospheric sources of error, they need to be validated carefully by correlative measurements. The quality control and validation of satellite measurements on the global scale, as well as in the long term, is one of the goals of the Network for the Detection of Stratospheric Change (NDSC). Started in 1991, at the present time the NDSC includes five primary and two dozen complementary stations distributed from the Arctic to the Antarctic, comprising a variety of instruments such as UV-visible spectrometers, Fourier transform infrared spectrometers, lidars, and millimeter-wave radiometers. After an overview of the main sources of uncertainty which could perturb the measurements from space, and of the ground-based data provided by the NDSC for their validation, this paper will focus, as an example, on the measurement of total ozone by Earth Probe Total Ozone Mapping Spectrometers (TOMS), ADEOS TOMS and ERS-2 Global Ozone Monitoring Experiment (GOME) and their validations. The data recorded between summer 1996 and April 1997 by 16 Systeme d'Analyse par observations zenithales (SAOZ)NV-visible spectrometers distributed over a range of latitudes from the Arctic to the Antarctic, and by Dobson and Brewer spectrophotometers operating at selected sites of the NDSC alpine and Antarctic stations, are used to investigate the solar zenith angle (SZA) dependence, the dispersion, the time-dependent drift, and the possible differences of sensitivity of the space-based sensors. Although the comparison demonstrates an excellent agreement to within +/-2%-4% between all space- and ground-based instruments at northern middle latitudes, it also reveals significant systematic features, such as a SZA dependence with TOMS beyond 80 degrees, a seasonal SZA dependence with COME beyond 70 degrees, a systematic bias of a few percent between satellite and SAOZ observations of low ozone columns in the southern Tropics, a difference in sensitivity to ozone between the COME and ground-based sensors at high latitudes, and an interhemispheric difference of TOMS with the ground-based observations. C1 Inst Aeron Spatiale Belgique, BIRA, B-1180 Brussels, Belgium. CNRS, Serv Aeron, F-91371 Verrieres Buisson, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Lambert, JC (reprint author), Inst Aeron Spatiale Belgique, BIRA, Ave Circulaire 3, B-1180 Brussels, Belgium. RI Gleason, James/E-1421-2012 NR 70 TC 35 Z9 35 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JAN 15 PY 1999 VL 56 IS 2 BP 176 EP 193 DI 10.1175/1520-0469(1999)056<0176:IOPTPP>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160JC UT WOS:000078226000004 ER PT J AU Waters, JW Read, WG Froidevaux, L Jarnot, RF Cofield, RE Flower, DA Lau, GKK Pickett, HM Santee, ML Wu, DL Boyles, MA Burke, JR Lay, RR Loo, MS Livesey, NJ Lungu, TA Manney, GL Nakamura, LL Perun, VS Ridenoure, BP Shippony, Z Siegel, PH Thurstans, RP Harwood, RS Pumphrey, HC Filipiak, MJ AF Waters, JW Read, WG Froidevaux, L Jarnot, RF Cofield, RE Flower, DA Lau, GKK Pickett, HM Santee, ML Wu, DL Boyles, MA Burke, JR Lay, RR Loo, MS Livesey, NJ Lungu, TA Manney, GL Nakamura, LL Perun, VS Ridenoure, BP Shippony, Z Siegel, PH Thurstans, RP Harwood, RS Pumphrey, HC Filipiak, MJ TI The UARS and EOS microwave limb sounder (MLS) experiments SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article; Proceedings Paper CT Conference on Global Measurement Systems for Atmospheric Composition CY MAY, 1997 CL TORONTO, CANADA SP Int Global Atmospher Chem Program, Stratospher Proc & Their Role Climate, Global Atmospher Watch, Canadian Space Agcy, Atmospher Environm Serv ID ATMOSPHERE RESEARCH SATELLITE; TROPOSPHERIC WATER-VAPOR; POLAR VORTEX CONDITIONS; ARCTIC OZONE DEPLETION; SOUTHERN-HEMISPHERE; STRATOSPHERIC CLO; INTERHEMISPHERIC DIFFERENCES; TEMPERATURE-MEASUREMENTS; HYDROGEN-PEROXIDE; TROPICAL PACIFIC AB The Microwave Limb Sounder (MLS) experiments obtain measurements of atmospheric composition, temperature, and pressure by observations of millimeter- and submillimeter-wavelength thermal emission as the instrument field of view is scanned through the atmospheric limb. Features of the measurement technique include the ability to measure many atmospheric gases as well as temperature and pressure, to obtain measurements even in the presence of dense aerosol and cirrus, and to provide near-global coverage on a daily basis at all times of day and night from an orbiting platform. The composition measurements are relatively insensitive to uncertainties in atmospheric temperature. An accurate spectroscopic database is available, and the instrument calibration is also very accurate and stable. The first MLS experiment in space, launched on the (NASA) Upper Atmosphere Research Satellite (UARS) in September 1991, was designed primarily to measure stratospheric profiles of ClO, O(3), H(2)O, and atmospheric pressure as a vertical reference. Global measurement of ClO, the predominant radical in chlorine destruction of ozone, was an especially important objective of UARS MLS. Ail objectives of UARS MLS have been accomplished and additional geophysical products beyond those for which the experiment was designed have been obtained, including measurement of upper-tropospheric water vapor, which is important for climate change studies. A follow-on MLS experiment is being developed for NASA's Earth Observing System (EOS) and is scheduled to be launched on the EOS CHEMISTRY platform in late 2002. EOS MLS is designed for many stratospheric measurements, including HO, radicals, which could not be measured by UARS because adequate technology was not available, and better and more extensive upper-tropospheric and lower-stratospheric measurements. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Edinburgh, Dept Meteorol, Edinburgh, Midlothian, Scotland. RP Waters, JW (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-701, Pasadena, CA 91109 USA. EM joe@mls.jpl.nasa.gov RI Wu, Dong/D-5375-2012 NR 158 TC 144 Z9 147 U1 1 U2 12 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JAN 15 PY 1999 VL 56 IS 2 BP 194 EP 218 DI 10.1175/1520-0469(1999)056<0194:TUAEML>2.0.CO;2 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160JC UT WOS:000078226000005 ER PT J AU Reichle, HG Connors, VS AF Reichle, HG Connors, VS TI The mass of CO in the atmosphere during October 1984, April 1994, and October 1994 SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article; Proceedings Paper CT Conference on Global Measurement Systems for Atmospheric Composition CY MAY, 1997 CL TORONTO, CANADA SP Int Global Atmospher Chem Program, Stratospher Proc & Their Role Climate, Global Atmospher Watch, Canadian Space Agcy, Atmospher Environm Serv ID CARBON-MONOXIDE AB The latitudinal distribution and the total mass of CO in the atmosphere are calculated for October 1984, April 1994, and October 1994 based upon measurements made by the MAPS experiment aboard the space shuttle. It is shown that the amount of CO in October 1994 was greater than in October 1984 and that this increase was dominated by increases in the tropical regions, particularly in the region north and northwest of Australia. C1 N Carolina State Univ, Coll Phys & Math Sci, Dept Marine Earth & Atmospher Sci, Raleigh, NC 27695 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. N Carolina State Univ, Raleigh, NC 27695 USA. RP Reichle, HG (reprint author), N Carolina State Univ, Coll Phys & Math Sci, Dept Marine Earth & Atmospher Sci, Box 8208, Raleigh, NC 27695 USA. NR 8 TC 9 Z9 10 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JAN 15 PY 1999 VL 56 IS 2 BP 307 EP 310 DI 10.1175/1520-0469(1999)056<0307:TMOCIT>2.0.CO;2 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160JC UT WOS:000078226000013 ER PT J AU Park, Y Liang, S Lee, TK AF Park, Y Liang, S Lee, TK TI Phase diagram of the two-chain Hubbard model SO PHYSICAL REVIEW B LA English DT Article ID MATRIX RENORMALIZATION-GROUP; LADDER; SPIN; SUPERCONDUCTIVITY AB We have calculated the charge gap and spin gap for the two-chain Hubbard model as a function of the on-site Coulomb interaction and the interchain hopping amplitude. We used the density matrix renormalization group method and developed a method to calculate separately the gaps numerically for the symmetric and antisymmetric modes with respect to the exchange of the chain indices. We have found very different behaviors for the weak and strong interaction cases. Our calculated phase diagram is compared to the one obtained by Balents and Fisher using the weak coupling renormalization group technique. [S0163-1829(99)05404-1]. C1 Acad Sinica, Inst Phys, Taipei 11529, Taiwan. Natl Ctr Theoret Sci, Hsinchu, Taiwan. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Park, Y (reprint author), Acad Sinica, Inst Phys, Taipei 11529, Taiwan. NR 16 TC 12 Z9 12 U1 1 U2 3 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD JAN 15 PY 1999 VL 59 IS 4 BP 2587 EP 2590 DI 10.1103/PhysRevB.59.2587 PG 4 WC Physics, Condensed Matter SC Physics GA 164KL UT WOS:000078463100023 ER PT J AU Roesler, FL Moos, HW Oliversen, RJ Woodward, RC Retherford, KD Scherb, F McGrath, MA Smyth, WH Feldman, PD Strobel, DF AF Roesler, FL Moos, HW Oliversen, RJ Woodward, RC Retherford, KD Scherb, F McGrath, MA Smyth, WH Feldman, PD Strobel, DF TI Far-ultraviolet imaging spectroscopy of Io's atmosphere with HST/STIS SO SCIENCE LA English DT Article ID PLASMA TORUS; GALILEO MAGNETOMETER; GLOBAL DISTRIBUTION; EMISSION; TELESCOPE; STABILITY; MODEL; SO2 AB Well-resolved far-ultraviolet spectroscopic images of O I, S I, and previously undetected H I Lyman-alpha emission from lo were obtained with the Hubble space telescope imaging spectrograph (STIS), Detected O I and S I lines (1250 to 1500 angstroms) have bright equatorial spots (up to 2.5 kilorayleighs) that shift position with jovian magnetic field orientation; limb glow that is brighter on the hemisphere facing the jovian magnetic equator; and faint diffuse emission extending to similar to 20 lo radii. All O I and S I features brightened by similar to 50 percent in the last two images, concurrently with a ground-based observation of increased iogenic [O I] 6300-angstrom emission. The H I Lyman-alpha emission, consisting of a small, similar to 2-kilorayleigh patch near each pole, has a different morphology and time variation. C1 Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA. RP Woodward, RC (reprint author), Univ Wisconsin, Dept Phys, 1150 Univ Ave, Madison, WI 53706 USA. NR 39 TC 82 Z9 82 U1 2 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD JAN 15 PY 1999 VL 283 IS 5400 BP 353 EP 357 DI 10.1126/science.283.5400.353 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 157MV UT WOS:000078067000038 PM 9888844 ER PT J AU Arrigo, KR Robinson, DH Worthen, DL Dunbar, RB DiTullio, GR VanWoert, M Lizotte, MP AF Arrigo, KR Robinson, DH Worthen, DL Dunbar, RB DiTullio, GR VanWoert, M Lizotte, MP TI Phytoplankton community structure and the drawdown of nutrients and CO2 in the Southern Ocean SO SCIENCE LA English DT Article ID SEA AB Data from recent oceanographic cruises show that phytoplankton community structure in the floss Sea is related to mixed layer depth. Diatoms dominate in highly stratified waters, whereas Phaeocystis antarctica assemblages dominate where waters an more deeply mixed. The drawdown of both carbon dioxide (CO2) and nitrate per mole of phosphate and the rate of new production by diatoms are much Lower than that measured for P. antarctica. Consequently, the capacity of the biological community to draw down atmospheric CO2 and transport it to the deep ocean could diminish dramatically if predicted increases in upper ocean stratification due to climate warming should occur. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. San Francisco State Univ, Romberg Tuburon Ctr Environm Studies, Tiburon, CA 94920 USA. Sci Syst & Applicat, Lanham, MD 20706 USA. Stanford Univ, Stanford, CA 94305 USA. Univ Charleston, Grice Marine Lab, Charleston, SC 29412 USA. NOAA, Natl Environm Satellite Data & Informat Serv, Washington, DC 20233 USA. Univ Wisconsin, Dept Biol & Microbiol, Oshkosh, WI 54901 USA. RP Arrigo, KR (reprint author), NASA, Goddard Space Flight Ctr, Code 971-0, Greenbelt, MD 20771 USA. NR 9 TC 403 Z9 413 U1 7 U2 79 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD JAN 15 PY 1999 VL 283 IS 5400 BP 365 EP 367 DI 10.1126/science.283.5400.365 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 157MV UT WOS:000078067000041 ER PT J AU Skinner, CJ Justtanont, K Tielens, AGGM Betz, AL Boreiko, RT Baas, F AF Skinner, CJ Justtanont, K Tielens, AGGM Betz, AL Boreiko, RT Baas, F TI Modelling the dust and gas outflows from IRC+10 216 - I. Ground-based and airborne observations SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE stars : AGB and post-AGB; stars : carbon; circumstellar matter; stars : individual : IRC+10 216; stars : mass-loss; radio lines : stars ID CIRCUMSTELLAR MOLECULAR-EMISSION; CARBON-MONOXIDE EMISSION; CO J=1-0 OBSERVATIONS; MASS-LOSS RATE; EVOLVED STARS; LINE-PROFILES; ENVELOPE; GIANT; SHELLS; HCN AB We have developed a model for the dust and gas envelope of the C star IRC+10216. Spherical symmetry is assumed, and the model consistently solves the full radiative transfer problem for the rotationally excited far-infrared and submillimetre wavelength CO lines and for the dust continuum. New observations of the CO J = 9-8 and 12-11 lines, made with the Kuiper Airborne Observatory, are presented. The model accounts for the first 32 rotational states in the lowest two vibrational levels of CO, and is shown to yield satisfactory fits to both line profiles and spatial maps of the CO J = 1-0, 2-1, 3-2, 4-3, 6-5, 7-6, 9-8 and 12-11 lines. The dust model yields a good fit to the spectral energy distribution from the near-IR to millimetre wavelengths, assuming a distance to the star of 170 pc. From the CO model we are able to confirm previous findings that the gas in the outer envelope is heated by the photoelectric effect, and we also fmd that the mass-loss rate must be of order 5x10(-5) M-. yr(-1), with a gas-to-dust ratio of approximately 220, in order to fit all the CO observations and the spectral energy distribution simultaneously, and to predict accurately the observed wind terminal velocity via radiative acceleration of the dust grains which are momentum-coupled to the gas. The gas temperature distribution is found to be lower than predicted by a simple three-level molecule approach which has been found to work for the envelopes of O-rich asymptotic giant branch stars, but is in good agreement with some previously published models for this source. in contrast with some previously published models, we find no evidence for a recent change in mass-loss rate. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. SRON, NL-9700 AV Groningen, Netherlands. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Joint Astron Ctr, Hilo, HI 96720 USA. RP Skinner, CJ (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. OI /0000-0003-1689-9201 NR 73 TC 23 Z9 23 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JAN 11 PY 1999 VL 302 IS 2 BP 293 EP 304 DI 10.1046/j.1365-8711.1999.02113.x PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 164RL UT WOS:000078477300010 ER PT J AU Lawrence, DJ Barbier, LM Beatty, JJ Binns, WR Christian, ER Crary, DJ Ficenec, DJ Hink, PL Klarmann, J Krombel, KE Mitchell, JW Rauch, BF Sposato, SH Streitmatter, RE Waddington, CJ AF Lawrence, DJ Barbier, LM Beatty, JJ Binns, WR Christian, ER Crary, DJ Ficenec, DJ Hink, PL Klarmann, J Krombel, KE Mitchell, JW Rauch, BF Sposato, SH Streitmatter, RE Waddington, CJ TI Large-area scintillating-fiber time-of-flight/hodoscope detectors for particle astrophysics experiments SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article DE scintillating fibers; time-of-flight detectors; hodoscope; cosmic ray detectors ID GALACTIC COSMIC-RAYS; SUPERNOVA-REMNANTS AB A new generation of detectors of ultra-heavy (UH) cosmic rays is being built which require the use of large-area, light-weight detector elements. In this paper, we present the design and operation of a new type of scintillating optical fiber detector, which can serve as both a time-of-Eight (TOF) detector and coded hodoscope (i.e. trajectory detector). We demonstrate that this type of detector can make TOF measurements with a time resolution of 48 ps. We also present results of position measurements from a large area TOF/hodoscope that was flown on a high-altitude balloon Eight in August, 1995. Finally, we discuss areas of modification and improvements that can be made to these detectors to enable them to be more useful for making UH cosmic ray measurements. (C) 1999 Elsevier Science B.V. All rights reserved. C1 Washington Univ, St Louis, MO 63130 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Penn State Univ, University Pk, PA 16802 USA. Univ Minnesota, Minneapolis, MN 55455 USA. RP Lawrence, DJ (reprint author), Univ Calif Los Alamos Natl Lab, MS D466, Los Alamos, NM 87545 USA. RI Christian, Eric/D-4974-2012; Lawrence, David/E-7463-2015; Beatty, James/D-9310-2011 OI Christian, Eric/0000-0003-2134-3937; Lawrence, David/0000-0002-7696-6667; Beatty, James/0000-0003-0481-4952 NR 8 TC 10 Z9 10 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD JAN 11 PY 1999 VL 420 IS 3 BP 402 EP 415 DI 10.1016/S0168-9002(98)01164-4 PG 14 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 155CX UT WOS:000077929400004 ER PT J AU Oh, SP Spergel, DN Hinshaw, G AF Oh, SP Spergel, DN Hinshaw, G TI An efficient technique to determine the power spectrum from cosmic microwave background sky maps SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; methods : statistical ID PRIMORDIAL INHOMOGENEITY; ANISOTROPY EXPERIMENTS; COEFFICIENTS AB There is enormous potential to advance cosmology from statistical characterizations of cosmic microwave background (CMB) sky maps. The angular power spectrum of the microwave anisotropy is a particularly important statistic. Existing algorithms for computing the angular power spectrum of a pixelized map typically require O(N-3) operations and O(N-2) storage, where N is the number of independent pixels in the map. The MAP and Planck satellites will produce megapixel maps of the CMB temperature at multiple frequencies; thus, existing algorithms are not computationally feasible. In this article, we introduce an algorithm that requires O(N-2) operations and O(N-3/2) Storage that can find the minimum variance power spectrum from sky map data roughly one million times faster than was previously possible. This makes feasible an analysis that was hitherto intractable. C1 Princeton Univ Observ, Princeton, NJ 08544 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Oh, SP (reprint author), Princeton Univ Observ, Peyton Hall, Princeton, NJ 08544 USA. RI Spergel, David/A-4410-2011 NR 35 TC 92 Z9 92 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 551 EP 563 DI 10.1086/306629 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600004 ER PT J AU Steigman, G Hata, N Felten, JE AF Steigman, G Hata, N Felten, JE TI Nonnucleosynthetic constraints on the Baryon density and other cosmological parameters SO ASTROPHYSICAL JOURNAL LA English DT Review DE cosmology : theory; elementary particles; nuclear reactions, nucleosynthesis, abundances ID BIG-BANG NUCLEOSYNTHESIS; DARK-MATTER MODELS; HIGH DEUTERIUM ABUNDANCE; PRIMORDIAL HELIUM ABUNDANCE; LY-ALPHA FOREST; GALAXY CLUSTERS; INTERGALACTIC MEDIUM; POWER SPECTRUM; VELOCITY DISPERSION; LIKELIHOOD ANALYSIS AB Because the baryon-to-photon ratio eta(10) is in some; doubt, we drop nucleosynthetic constraints on eta(10) and fit the three cosmological parameters (h, Omega(M), eta(10)) to four observational constraints: Hubble parameter h(o) = 0.70 +/- 0.15, age of the universe t(o) = 14(-2)(+7) Gyr, cluster gas fraction f(o) = f(G) h(3/2) = 0.060 +/- 0.006, and effective shape parameter Gamma(o) = 0.255 +/- 0.017. Errors quoted are 1 sigma, and we assume Gaussian statistics. We experiment with a fifth constraint Omega(o) = 0.2 + 0.1. from clusters. We set the tilt parameter n = 1 and the gas enhancement factor Y = 0.9. We consider cold dark matter models (open and Omega(M) = 1) and hat Lambda CDM models. We omit HCDM models (tu which the Gamma(o) constraint does not apply). We test goodness of fit and draw confidence regions by the Delta chi(2) method. CDM models with Omega(M) = 1 (SCDM models) are accepted only because the large error on h, allows h < 0.5. Baryonic matter plays a significant role in Gamma(o) when Omega(M) similar to 1. Open CDM models are accepted only for Omega(M) greater than or similar to 0.4. The combination of the four other constraints with Omega(o) approximate to 0.2 is rejected in CDM models with 98% confidence, suggesting that light may not trace mass. Lambda CDM models give similar results. In all of these models, eta(10) greater than or similar to 6 is favored strongly over eta(10) less than or similar to 2. This suggests that reports of low deuterium abundances-on QSO lines df sight may be correct and that observational determinations of primordial He-4 may have systematic errors. Plausible variations on n and Y in our models do not change the results much. If we drop or change thecal Gamma(o) constraint, lower values of Omega(M) and eta(10) are permitted. The constraint Gamma(o) = 0.15 +/- 0.04, derived recently from the IRAS redshift survey, favors Omega(M) approximate to 0.3 and eta(10) approximate to 5 but does not exclude eta(10) approximate to 2. C1 Ohio State Univ, Dept Phys, Columbus, OH 43210 USA. Inst Adv Study, Princeton, NJ 08540 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Steigman, G (reprint author), Ohio State Univ, Dept Phys, 174 W 18Th Ave, Columbus, OH 43210 USA. EM steigman@mps.ohio-state.edu; hata@ias.edu; felten@stars.gsfc.nasa.gov NR 119 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 564 EP 575 DI 10.1086/306589 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600005 ER PT J AU Rothschild, RE Band, DL Blanco, PR Gruber, DE Heindl, WA MacDonald, DR Marsden, DC Jahoda, K Pierce, D Madejski, G Elvis, M Schwartz, DA Remillard, R Zdziarski, AA Done, C Svensson, R AF Rothschild, RE Band, DL Blanco, PR Gruber, DE Heindl, WA MacDonald, DR Marsden, DC Jahoda, K Pierce, D Madejski, G Elvis, M Schwartz, DA Remillard, R Zdziarski, AA Done, C Svensson, R TI Observation of centaurus A by the Rossi x-Ray timing explorer SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Centaurus A); galaxies : jets; galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; TYPE-2 SEYFERT-GALAXIES; ASCA OBSERVATIONS; OSSE OBSERVATIONS; COLD MATTER; EMISSION; REFLECTION; ABSORPTION; NGC-5128; SPECTRA AB The Rossi X-Ray Timing Explorer made a short (10 ks) observation of the radio galaxy Centaurus A on 1996 August 14. Analysis of the combined 2.5-240 keV spectrum has revealed a heavily absorbed (N(H) = 9.42 +/- 0.24 x 10(22) cm(-2)) primary power law (Gamma = 1.86 +/- 0.015) and an iron line due to fluorescence of cold matter (EW = 162 +/- 25 eV). Flux from a jet, a primary flux scattered into the line of sight, or a primary flux seen through a partial absorber was not required. The iron-line width is unresolved at the 95% confidence level (sigma < 0.54 keV). No significant variability in the iron-line flux is seen from measurements over the last two decades, while the overall continuum flux varied by more than a factor of 4, which implies that the line emission region is distant from that of the primary emission. While radio-quiet Seyfert galaxies exhibit spectral components attributable to Compton reflection from cold matter, Cen A reveals no such component (exposed solid angle ratio Omega/2 pi: less than or equal to 0.09). This supports unified models of active galaxies that have little difference between Seyfert 2 and low-luminosity radio galaxies. C1 Univ Calif San Diego, Ctr Astrophys & Space Sci 0424, La Jolla, CA 92093 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Harvard Smithsonian Astrophys Observ, Ctr Astrophys, Cambridge, MA 02138 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. Nicolaus Copernicus Astron Ctr, Warsaw, Poland. Univ Durham, Dept Phys, Durham, England. Stockholm Observ, Saltsjobaden, Sweden. RP Rothschild, RE (reprint author), Univ Calif San Diego, Ctr Astrophys & Space Sci 0424, La Jolla, CA 92093 USA. RI Jahoda, Keith/D-5616-2012; done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 34 TC 21 Z9 21 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 651 EP 658 DI 10.1086/306618 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600014 ER PT J AU Smith, DA Herter, T Haynes, MP Neff, SG AF Smith, DA Herter, T Haynes, MP Neff, SG TI The luminous starburst ring in NGC 7771: Sequential star formation? SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 7771); galaxies : interactions; galaxies : nuclei; galaxies : starburst; galaxies : stellar content; infrared : galaxies ID ACTIVE GALACTIC NUCLEI; MOLECULAR GAS; INTERACTING GALAXIES; INFRARED-EMISSION; VLA OBSERVATIONS; SPIRAL GALAXIES; IRAS GALAXIES; M82; RADIO; RESOLUTION AB Only two of the 20 highly luminous starburst galaxies analyzed by Smith et al. exhibit circumnuclear rings of star formation. These galaxies provide a link between similar to 10(11) L. luminosity class systems and classical, less-luminous ringed systems. In this paper, we report the discovery of a near-infrared counterpart to the 1.6 kpc diameter nuclear ring of radio emission in NGC 7771 (UGC 12815). The ring contains approximate to 10 radio-bright clumps and approximate to 10 near-infrared-bright clumps. A displacement between the peaks of the radio and the near-infrared emission indicates the presence of multiple generations of star formation. The estimated thermal emission from each radio source is equivalent to that of similar to 35,000 O6 stars. Each near-infrared-bright knot contains similar to 5000 red supergiants, on average. In the case that the radio-bright knots are 4 Myr old and the near-infrared-bright knots are approximate to 10 Myr old, each knot is characterized by a stellar mass of 10(7) M., and the implied time-averaged star formation rate is similar to 40 M. yr(-1) Several similarities are found between the properties of this system and other ringed and nonringed starbursts. Morphological differences between NGC 7771 and the starburst + Seyfert 1 galaxy NGC 7469 (UGC 12332) suggest that NGC 7771 may not be old enough to fuel an active galactic nucleus (AGN), or may not be capable of fueling an AGN. Alternatively, the differences may be unrelated to the presence or absence of an AGN and may simply reflect the possibility that star formation in rings is episodic. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Smith, DA (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. NR 84 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 669 EP 686 DI 10.1086/306605 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600016 ER PT J AU Cotera, AS Simpson, JP Erickson, EF Colgan, SWJ Burton, MG Allen, DA AF Cotera, AS Simpson, JP Erickson, EF Colgan, SWJ Burton, MG Allen, DA TI Isolated hot stars in the Galactic center vicinity SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxy : center; infrared : stars; stars : early-type; stars : Wolf-Rayet ID WOLF-RAYET STARS; EMISSION-LINE STARS; RADIO ARC; INFRARED OBSERVATIONS; MASSIVE STARS; CENTER REGION; SPECTROSCOPY; FILAMENTS; SPECTRA; CLUSTER AB Using near-infrared imaging and spectroscopy, we discuss the discovery of six emission-line sources within similar to 20 pc of Sgr A West but outside of the central parsec. The objects are coincident with stars seen in the J, H, and K' images; all have Bry (2.166 mu m) in emission, several also have He I (2.058 and 2.112/3 mu m), and some have He II (2.189 mu m) emission lines. Comparison of the H- and K-band spectra of the newly discovered stars with recently published infrared spectral atlases of optically classified stars suggests that most of these stars are similar to massive stars in transition (e.g., Ofpe/WN9, B[e], and LBV), although one is definitely a WN6 star. Two of the potential stars are associated with the radio emission regions A-D near Sgr A East, three are near or within the radio emission regions H1-H8 (nomenclature from Yusef-Zadeh & Morris), the last is near G0.10+0.02 and is likely to be associated with the G0.12+0.02 (Arches) cluster of stars, discussed in a previous paper. The stars are shown to be significant sources of ionization for their associated radio emission regions, with several capable of completely ionizing the regions. These results provide additional support for the idea that these thermal radio regions, and similar such regions in the Galactic center, are indeed photoionized by hot young stars. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ New S Wales, Sch Phys, Dept Astrophys, Sydney, NSW 2052, Australia. Anglo Australian Observ, Epping, NSW 2121, Australia. RI Colgan, Sean/M-4742-2014; OI Burton, Michael/0000-0001-7289-1998 NR 49 TC 48 Z9 48 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 747 EP 758 DI 10.1086/306595 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600022 ER PT J AU Gearhart, RA Wheeler, JC Swartz, DA AF Gearhart, RA Wheeler, JC Swartz, DA TI Carbon monoxide formation in SN 1987A SO ASTROPHYSICAL JOURNAL LA English DT Article DE molecular processes; radiative transfer; stars : abundances; supernovae : individual (SN 1987A) ID RADIATIVE ASSOCIATION; SN-1987A; MOLECULES; EJECTA AB The formation of carbon monoxide in the supernova SN 1987A at 200 days is investigated. Rather than the one-zone models that have previously been employed, this work utilizes a radially dependent radiative transport model to compute the temperature and ionization structure and the destruction of CO and CO+ by ultraviolet radiation The CO profile is computed assuming chemical equilibrium. Two models for the density and abundance profiles are examined: model 10H (unmixed) and model 10HMM (mixed) of Pinto & Woosley. Sensitivity to adopted rates and temperature as it might be affected by CO cooling is examined. The models give a total mass of similar to 10(-4) M-. at 200 days for the unmixed model, which is comparable with the estimated observed abundance by Spyromilio et al. but nearly 2 orders of magnitude less than the estimated observed abundance and that computed in thermal-chemical models by Liu & Dalgarno. The effect of different model assumptions and results concerning ionization structure and radiative transfer are discussed. We confirm that CO+ is not expected to be produced in significant amounts and that the amount of CO is sensitive to the degree of the mixing of the composition of various elements present in the ejecta. The microscopically mixed model for SN 1987A does not create sufficient CO, giving only similar to 10(-6) M, because of destruction of CO by charge exchange. The mixed model might make substantial amounts of CO if the rate for HeH+ + H --> H-2(+) +He were substantially increased, leading to more H-2, CH, and OH as intermediaries in the formation of CO. C1 Univ Texas, Dept Astron, Austin, TX 78712 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Gearhart, RA (reprint author), Univ Texas, Dept Astron, Austin, TX 78712 USA. NR 27 TC 24 Z9 24 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 944 EP 966 DI 10.1086/306588 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600040 ER PT J AU Scott, DM Leahy, DA AF Scott, DM Leahy, DA TI Rossi X-Ray Timing Explorer All-Sky Monitor observations of the 35 day cycle of Hercules X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : eclipsing; stars : individual (Hercules X-1); X-rays : stars ID LOW-STATE; PULSE PROFILE; VARIABILITY; SPECTRUM; UHURU AB Her X-l has been monitored nearly continuously in soft X-rays (2-12 keV) since 1996 February by the Ah-Sky Monitor on board the Rossi X-Ray Timing Explorer. We present an analysis of these observations, which include 23 contiguous 35 day cycles. We present the best-yet average 35 day cycle light curve for Her X-l. Thirty-five day light-curve features such as eclipses and absorption dips, and the alternating occurrence of the main high and short high states, are well measured. The occurrence of X-ray eclipse during the low state is confirmed, as is the presence of main high states that "turn-on" sharply at orbital phases 0.23 and 0.68. The main high state covers 35 day phases 0-0.31, and the short high state covers phases 0.57-0.79, with phase 0 defined by main high state turn-on. We find extended ingresses and egresses for the short high slate. Marching preeclipse absorption dips progressively become shallower during the main high state. The marching preeclipse dip period is best determined from reanalysis of archival data as 1.651 +/- 0.002 days if the dip marching can be extrapolated from the main high state into he short high state or 1.646 +/- 0.003 using dips within single main high states alone. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Lab ES84, Huntsville, AL 35812 USA. Univ Calgary, Dept Phys, Calgary, AB T2N 1N4, Canada. RP Scott, DM (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab ES84, Huntsville, AL 35812 USA. NR 27 TC 59 Z9 60 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 974 EP 985 DI 10.1086/306631 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600042 ER PT J AU Murphy, RJ Share, GH DelSignore, KW Hua, XM AF Murphy, RJ Share, GH DelSignore, KW Hua, XM TI Surprisingly intense neutron emission from a flare behind the limb of the sun SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; Sun : abundances; Sun : flares; Sun : X-rays, gamma rays ID GAMMA-RAY SPECTROSCOPY; SOLAR-FLARE; ABUNDANCES AB The Oriented Scintillation Spectrometer Experiment onboard the Compton Gamma Ray Observatory observed a strong flux of neutrons from the behind-the-limb flare that occurred on 1991 June 1. This is surprising if the neutrons were produced by thin-target interactions in the Sun's corona, as is suggested by gamma-ray observations of this hare made by Granat/PHEBUS. We compare neutron and gamma-ray observations of the June 1 hare with thick-target emissions observed from a hare 3 days later, where the interactions took place in the chromosphere and photosphere. A very hard spectrum for the accelerated particles is required to account for the number of neutrons observed on June 1 if they were produced by thin-target interactions in the corona. C1 USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. RP Murphy, RJ (reprint author), USN, Res Lab, EO Hulburt Ctr Space Res, Code 7650, Washington, DC 20375 USA. NR 22 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 1011 EP 1017 DI 10.1086/306614 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600045 ER PT J AU Ciaravella, A Raymond, JC Strachan, L Thompson, BJ St Cyr, OC Gardner, L Modigliani, A Antonucci, E Kohl, J Noci, G AF Ciaravella, A Raymond, JC Strachan, L Thompson, BJ St Cyr, OC Gardner, L Modigliani, A Antonucci, E Kohl, J Noci, G TI Ultraviolet and optical observations of a coronal transient with SOHO SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : UV radiation ID MASS EJECTIONS; SOLAR; SPECTROMETER; VELOCITY; FIELDS; LASCO; IONS AB A coronal transient was observed on 1997 March 6 at 1.6 R. over an active region on the east limb. We observed both the edge of horizontally compressed gas and the diffuse curtain of coronal material. The region was monitored for 4 hr, and the H I Ly alpha, O VI lambda lambda 1031.91, 1037.61, N V lambda lambda 1242.80, 1238.80, and O V] lambda 1218.35 lines were detected during the ejection evolution. The density, velocity, temperature, and oxygen abundance of the ejected plasma have been obtained from the observed spectra. Intermediate temperature lines of N V, O VI, and O V show a large enhancement, suggesting a quite narrow range of plasma temperature around 4 x 10(5) K. Doppler shifts of the ejected material evolve from an initial blueshift of 100 km s(-1) to a redshift of 145 km s(-1). The outflow velocity, as determined by Doppler dimming analysis of the O VI doublet, is only about 20 km s(-1). C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Dipartimento Sci Fis & Astron, I-90134 Palermo, Italy. NASA, Goddard Space Flight Ctr, NRL, CPI, Greenbelt, MD 20771 USA. Dipartimento Astron & Sci Spazio, I-50125 Florence, Italy. Osserv Astron Torino, I-10125 Turin, Italy. RP Ciaravella, A (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Thompson, Barbara/C-9429-2012 NR 27 TC 18 Z9 18 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 1053 EP 1063 DI 10.1086/306622 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600048 ER PT J AU Saba, JLR Schmelz, JT Bhatia, AK Strong, KT AF Saba, JLR Schmelz, JT Bhatia, AK Strong, KT TI Fe XVII soft X-ray lines: Theory and data comparisons SO ASTROPHYSICAL JOURNAL LA English DT Article DE line : formation; scattering; Sun : corona; Sun : X-rays, gamma rays; techniques : spectroscopic ID CORONAL ACTIVE REGIONS; SPECTRAL-LINES; SOLAR; OPACITY; DENSITY; RATIOS AB Fe XVII soft X-ray spectral emission lines are examined using data from the Flat Crystal Spectrometer (FCS) on the Solar Maximum Mission satellite. Results are compared with theoretical calculations and with other recent observational results. Disparate findings from different studies on the inferred opacity of the bright resonance line at 15.01 Angstrom and on its center-to-limb behavior are reviewed. Present limitations on the use of resonance scattering to infer coronal plasma densities and absolute elemental abundances are discussed. An analysis is made of the temperature-insensitive ratio of the 15.01 Angstrom line of Fe XVII to the optically thin 16.78 Angstrom. line. This analysis shows that approximately half of the photons expected in the 15.01 Angstrom line are missing from the bright emission cores of quiescent active regions on the solar disk; the missing fraction increases at most by 50% near the solar limb. If the missing flux has been resonantly scattered out of the line of sight, then the equivalent optical depth at line center of the 15.0 Angstrom line is tau(0) similar to 2 on the disk, based on a simple escape probability treatment for a slab geometry. This suggests that the effects of resonance scattering for other FCS lines, with the possible exception of the O vm doublet at 18.97 Angstrom should be negligible for quiescent active region conditions. This is consistent with the lack of systematic center-to-limb dependence found previously for FCS lines other than Fe XVII at 15.01 Angstrom. Yohkoh Soft X-ray Telescope measurements of the expected lines of sight for active regions as a function of location on the solar disk, and resonance scattering results from other soft X-ray active region data sets all support a trend of increased opacity at the limb compared to disk center. C1 NASA, Goddard Space Flight Ctr, Lockheed Martin solar & Astrophys Lab, Greenbelt, MD 20771 USA. Univ Memphis, Dept Phys, Memphis, TN 38152 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Lockheed Martin Solar & Astrophys Lab, Palo Alto, CA 94304 USA. RP Saba, JLR (reprint author), NASA, Goddard Space Flight Ctr, Lockheed Martin solar & Astrophys Lab, Code 682-3,SOHO EAF,Bldg 26,Room G1, Greenbelt, MD 20771 USA. EM jlrs@sdac.nascom.nasa.gov; jschmelz@memphis.edu; bhatia@stars.gsfc.nasa.gov; keith.strong@lmco.com NR 26 TC 51 Z9 52 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP 1064 EP 1077 DI 10.1086/306590 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NJ UT WOS:000079157600049 ER PT J AU Gaidos, EJ AF Gaidos, EJ TI Observational constraints on late heavy bombardment episodes around young solar analogs SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; infrared : stars; solar system : formation ID ZODIACAL CLOUD; ASTEROID BELT; EARLY EARTH; SAO STARS; ORIGIN; LIFE; IMPACTS; RECORD; ATMOSPHERE; EVOLUTION AB Thermal emission from dust is investigated around 36 nearby G and K stars selected as analogs to the young Sun during the period of late heavy bombardment on the Moon(prior to 3.8 Ga). Measurements or upper limits at 12, 25, and 60 mu m wavelengths were obtained from observations by the Infrared Astronomical Satellite (IRAS), and photosphere contributions were subtracted using the models of Kurucz and ground-based optical and near-infrared data. A single star, HD 128400, has circumstellar emission that is consistent with a 490 K blackbody with an effective area similar to 7 x 10(3) times that of the present solar system zodiacal cloud. Emission from 260 K dust at a mean level exceeding 900 times the present zodiacal cloud can be ruled out for the remaining 35 stars. A model of dust production by cometary impacters scaled to the lunar cratering record shows that dust from late heavy bombardment episodes around these stars would fall below IRAS detection levels after 500 Myr (4.1 Ga). The emission from HD 128400 is broadly consistent with the model at the star's 300 Myr age. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gaidos, EJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 60 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP L131 EP L134 DI 10.1086/311819 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NK UT WOS:000079157700013 ER PT J AU Hurley, K Li, P Kouveliotou, C Murakami, T Ando, M Strohmayer, T van Paradijs, J Vrba, F Luginbuhl, C Yoshida, A Smith, I AF Hurley, K Li, P Kouveliotou, C Murakami, T Ando, M Strohmayer, T van Paradijs, J Vrba, F Luginbuhl, C Yoshida, A Smith, I TI ASCA discovery of an X-ray pulsar in the error box of SGR 1900+14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; stars : neutron; supernova remnants; X-rays : stars ID SOFT GAMMA-REPEATERS; IDENTIFICATION; LOCALIZATION; SGR-1900+14; COINCIDENT; SGR1806-20; TRANSIENT AB We present a 2-10 keV ASCA observation of the field around the soft gamma repeater SGR 1900+14. One quiescent X-ray source was detected in this observation, and it was in the SGR error box. In 2-10 keV X-rays, its spectrum may be fitted by a power Law with index -2.2, and its unabsorbed flux is 9.6 x 10(-12) ergs cm(-2) s(-1). We also find a clear 5.16 s period. The properties of the three well-studied soft gamma repeaters are remarkably similar to one another, and they provide evidence that all off them are associated with young, strongly magnetized neutron stars in supernova remnants. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Alabama, Huntsville, AL 35899 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. USN Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA. RIKEN, Wako, Saitama 35101, Japan. Rice Univ, Dept Space Phys & Astron, Houston, TX 77005 USA. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NR 26 TC 163 Z9 164 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP L111 EP L114 DI 10.1086/311820 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NK UT WOS:000079157700008 ER PT J AU Hurley, K Kouveliotou, C Woods, P Cline, T Butterworth, P Mazets, E Golenetskii, S Frederics, D AF Hurley, K Kouveliotou, C Woods, P Cline, T Butterworth, P Mazets, E Golenetskii, S Frederics, D TI Reactivation and precise interplanetary network localization of the soft gamma repeater SGR 1900+14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; stars : neutron; supernova remnants ID RAY TRANSIENT; SGR-1900+14; IDENTIFICATION; COUNTERPART; SGR1806-20 AB In 1998 May, the soft gamma repeater SGR 1900+14 emerged from several years of quiescence and emitted a series of intense bursts, one with a time history unlike any previously observed from this source. Triangulation using Ulysses, BATSE, and KONUS data gives a 1.6 arcmin(2) error box near the Galactic supernova remnant G42.8+0.6. This error box contains a quiescent soft X-ray source that is probably a neutron star associated with the soft repeater. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. AF Ioffe Physicotech Inst, St Petersburg 194021, Russia. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI Golenetskii, Sergey/B-3818-2015 NR 28 TC 59 Z9 59 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP L107 EP L109 DI 10.1086/311821 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NK UT WOS:000079157700007 ER PT J AU Kouveliotou, C Strohmayer, T Hurley, K van Paradijs, J Finger, MH Dieters, S Woods, P Thompson, C Duncan, RC AF Kouveliotou, C Strohmayer, T Hurley, K van Paradijs, J Finger, MH Dieters, S Woods, P Thompson, C Duncan, RC TI Discovery of a magnetar associated with the soft gamma repeater SGR 1900+14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : neutron; stars : magnetic fields ID HIGH-ENERGY TRANSIENT; NEUTRON-STARS; RAY REPEATERS; X-RAY; SGR1806-20; BEHAVIOR AB The soft gamma repeater SGR 1900+14 became active again on 1998 June after a long period of quiescence; it remained at a low state of activity until 1998 August, when it emitted a. series of extraordinarily intense outbursts. We have observed the source with the Rossi X-Ray Timing Explorer twice, during the onset of each active episode. We confirm the pulsations at the 5.16 s period reported earlier from SGR 1900+14. Here we report the detection of a secular spin-down of the pulse period at an average rate of 1.1 x 10(-10) s s(-1). In view of the strong similarities between SGRs, we attribute the spin-down of SGR 1900+14 to magnetic dipole radiation, possibly accelerated by a quiescent flux, as in the case of SGR 1806-20. This allows an estimate of the pulsar dipolar magnetic field, which is (2-8) x 10(14) G. Our results confirm that SGRs are magnetars. C1 Univ Space Res Assoc, Washington, DC USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. RP Kouveliotou, C (reprint author), Univ Space Res Assoc, Washington, DC USA. EM chryssa.kouveliotou@msfc.nasa.gov NR 36 TC 301 Z9 301 U1 0 U2 7 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP L115 EP L118 DI 10.1086/311813 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NK UT WOS:000079157700009 ER PT J AU Murakami, T Kubo, S Shibazaki, N Takeshima, T Yoshida, A Kawai, N AF Murakami, T Kubo, S Shibazaki, N Takeshima, T Yoshida, A Kawai, N TI Accurate position of SGR 1900+14 by bursts and changes in pulse period and folded pulse profile with ASCA SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; stars : individual (SGR 1900+14); stars : neutron ID RAY REPEATER SGR-1900+14; MAGNETIZED NEUTRON-STARS; SOFT GAMMA-REPEATERS; X-RAY; SGR1806-20; IDENTIFICATION; COINCIDENT; TRANSIENT AB The Advanced Satellite for Cosmology and Astrophysics (ASCA) observed the soft gamma repeater SGR 1900+14 on 1998 April 30-May 1 and discovered a pulsar with a period of 5.1589715(8) s from the known X-ray source of RX L190714.2+0919.3. Four months later, on September 16-17, ASCA observed SGR 1900+14 again just after the giant burst on 1998 August 27. Comparing the observations in September with those in April, there are several changes in characteristics. The pulse period-hanged to 5.160295(3) s, and thus the long-term period derivative is 1.1 x 10(-10) s s(-1). This strongly supports a magnetar model. The folded pulse profile in 2-10 keV largely changed from three peaks in April to one simple peak, while the steady intensity increased by a factor of 2. Finally, we successfully determined the accurate location of SGR 1900+14 by the bursts with an accuracy of 115 in diameter. C1 Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Rikkyo Univ, Tokyo 1718501, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20711 USA. Inst Phys & Chem Res, Wako, Saitama 35101, Japan. RP Murakami, T (reprint author), Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2298510, Japan. EM murakami@astro.isas.ac.jp NR 38 TC 40 Z9 41 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 1999 VL 510 IS 2 BP L119 EP L122 DI 10.1086/311822 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NK UT WOS:000079157700010 ER PT J AU Saraf, AK Foster, JL Singh, P Tarafdar, S AF Saraf, AK Foster, JL Singh, P Tarafdar, S TI Passive microwave data for snow-depth and snow-extent estimations in the Himalayan mountains SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID REGION AB In high mountainous areas, such as the Himalayan Range where snow melt run-off contributes substantially to streamflow, information on snow depth and snow areal extent is vital for the estimation of streamflow and for water resources management. Microwave radiation penetrates through clouds and snow-packs and is thus considered an important tool for providing water equivalent information on snow fields. The scanning multichannel microwave radiometer (SMMR) on board the NIMBUS-7 satellite acquired passive microwave data for 9 years (1978-1987). These SMMR data are used to test a snow algorithm that is applicable for high elevation areas (> 3500 m) in the Himalayan Range. The study demonstrates promising results, suggesting the application of SMMR data to derive snow-depth and snow-extent information for the Himalayan region. The generated snow maps can be used for various hydrological applications. The limited availability of field data and its comparison with the SMMR data (which are areal in nature), are major limitations in achieving close correlations between two observations. This is the first application of SMMR data for the determination of snow parameters in the Indian Himalayas. Thus, such an application sets a pace for further research and application of passive microwave data in the most rugged terrains of the world. C1 Univ Roorkee, Dept Earth Sci, Roorkee 247667, Uttar Pradesh, India. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Greenbelt, MD 20771 USA. Natl Inst Hydrol, Roorkee 247667, Uttar Pradesh, India. RP Saraf, AK (reprint author), Univ Roorkee, Dept Earth Sci, Roorkee 247667, Uttar Pradesh, India. NR 13 TC 9 Z9 16 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JAN 10 PY 1999 VL 20 IS 1 BP 83 EP 95 DI 10.1080/014311699213613 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 165RN UT WOS:000078535400007 ER PT J AU Panda, J AF Panda, J TI An experimental investigation of screech noise generation SO JOURNAL OF FLUID MECHANICS LA English DT Article ID SUPERSONIC JETS; TONES; SHOCK AB The screech noise generation process from supersonic underexpanded jets, issuing from a sonic nozzle at pressure ratios of 2.4 and 3.3 (fully expanded Mach number, M-j = 1.19 and 1.42), was investigated experimentally. The extremely detailed data provide a fresh, new look at the screech generation mechanism. Spark schlieren visualization at different phases of the screech cycle clearly shows the convection of the organized turbulent structures over a train of shock waves. The potential pressure held (hydrodynamic fluctuations) associated with the organized structures is fairly intense and extends outside the shear layer. The time evolution of the near-held pressure fluctuations was obtained from phase-averaged microphone measurements. Phase-matched combined views of schlieren photographs and pressure fluctuations show the sound generation process. The individual compression and rarefaction parts of the sound waves are found to be generated from similar hydrodynamic fluctuations. A partial interference between the upstream-propagating sound waves and the downstream-propagating hydrodynamic Raves is found to be present along the jet boundary. The partial interference manifests itself as a standing wave in the root-mean-square pressure fluctuation data. The standing wavelength is found to be close to, but somewhat different from, the shock spacing. An outcome of the interference is a curious 'pause and go' motion of the sound waves along the jet periphery. Interestingly; a length scale identical to the standing wavelength is found to be present inside the jet shear layer. The coherent fluctuations and the convective velocity of the organized vortices are found to be modulated periodically, and the periodicity is found to match with the standing wavelength distance rather than the shock spacing. The reason for the appearance of this additional length scale, different from the shock spacing, could not be explained. Nevertheless, it is demonstrated that an exact screech frequency formula can be derived from the simple standing wave relationship. The exact relationship shows that the correct spacing between the sources, for a point source model similar to that of Powell (1953), should be a standing wavelength (not the shock spacing). C1 Modern Technol Corp, Middleburg Hts, OH 44130 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Panda, J (reprint author), Modern Technol Corp, Middleburg Hts, OH 44130 USA. NR 34 TC 45 Z9 46 U1 1 U2 10 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JAN 10 PY 1999 VL 378 BP 71 EP 96 DI 10.1017/S0022112098003383 PG 26 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 166MZ UT WOS:000078581600003 ER PT J AU Dietz, AJ AF Dietz, AJ TI Local boundary-layer receptivity to a convected free-stream disturbance SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TOLLMIEN-SCHLICHTING WAVES; SURFACE GEOMETRY; ACOUSTIC-WAVES; LEADING-EDGE; EVOLUTION; GENERATION AB An investigation of the local receptivity of a Blasius boundary layer to a harmonic vortical disturbance is presented as a step towards understanding boundary-layer receptivity to free-stream turbulence. Although there has been solid experimental verification of the linear theory describing acoustic receptivity of boundary layers, this was the first experimental verification of the mechanism behind local receptivity to a convected disturbance. The harmonic wake from a vibrating ribbon positioned upstream of a flat plate provided the free-stream disturbance. Two-dimensional roughness elements on the surface of the plate acted as a local receptivity site. Hot-wire measurements in the boundary layer downstream of the roughness confirmed the generation of Tollmien-Schlichting (TS) instability waves by an outer-layer interaction between the long-wavelength convected disturbance and the short-scale mean-flow distortion due to the roughness. The characteristics of the instability waves were carefully measured to ensure that their behaviour was correctly modelled by linear stability theory. This theory was then used to determine the immeasurably small initial wave amplitudes resulting from the receptivity process, from wave amplitudes measured downstream. Tests were performed to determine the range of validity of the linear assumptions made in current receptivity theories. Experimental data obtained in the linear regime were then compared to theoretical results of other authors by expressing the experimental data in the form of an efficiency function which is independent of the free-stream amplitude, roughness height and roughness geometry. Reasonable agreement between the experimental and theoretical efficiency functions was obtained over a range of frequencies and Reynolds numbers. C1 NASA, Ames Res Ctr, Fluid Mech Lab, Moffett Field, CA 94035 USA. RP Dietz, AJ (reprint author), NASA, Ames Res Ctr, Fluid Mech Lab, Moffett Field, CA 94035 USA. NR 42 TC 34 Z9 36 U1 0 U2 2 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JAN 10 PY 1999 VL 378 BP 291 EP 317 DI 10.1017/S0022112098003243 PG 27 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 166MZ UT WOS:000078581600011 ER PT J AU Bills, BG James, TS Mengel, JG AF Bills, BG James, TS Mengel, JG TI Climatic impact of glacial cycle polar motion: Coupled oscillations of ice sheet mass and rotation pole position SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID LATE CENOZOIC UPLIFT; VISCOSITY STRUCTURE; ASTRONOMICAL THEORY; LOWER MANTLE; MODEL; EARTH; SENSITIVITY; PLEISTOCENE; TRANSITION; AGE AB Precessional motion of Earth's rotation axis relative to its orbit is a well-known source of long-period climatic variation. It is less well appreciated that growth and decay of polar ice sheets perturb the symmetry of the global mass distribution enough that the geographic location of the rotation axis will change by at least 15 km and possibly as much as 100 km during a single glacial cycle. This motion of the pole will change the seasonal and latitudinal pattern of temperatures. We present calculations, based on a diurnal average energy balance, which compare the summer and winter temperature anomalies due to a 1 degrees decrease in obliquity with those due to a 1 degrees motion of the rotation pole toward Hudson Bay. Both effects result in peak temperature perturbations of about 1 degrees Celsius. The obliquity change primarily influences the amplitude of the seasonal cycle, while the polar motion primarily changes the annual mean temperatures. The polar motion induced temperature anomaly is such that it will act as a powerful negative feedback on ice sheet growth. We also explore the evolution of the coupled system composed of ice sheet mass and pole position. Oscillatory solutions result from the conflicting constraints of rotational and thermal stability. A positive mass anomaly on an otherwise featureless Earth is in rotational equilibrium only at the poles or the equator. The two polar equilibria are rotationally unstable, and the equatorial equilibrium, though rotationally stable, is thermally unstable. We find that with a plausible choice for the strength of coupling between the thermal and rotational systems, relatively modest external forcing can produce significant response at periods of 10(4)-10(6) years, but it strongly attenuates polar motion at longer. periods. we suggest that these coupled oscillations may contribute to the observed dominance of 100 kyr glacial cycles since the mid-Pleistocene and will tend to stabilize geographic patterns that are suitable to glaciations. C1 NASA, Geodynam Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif San Diego, Scripps Inst Oceanog, Inst Geophys & Planetary Phys, La Jolla, CA 92093 USA. Geol Survey Canada, Pacific Geosci Ctr, Sidney, BC V8L 4B2, Canada. Space Applicat, Vienna, VA USA. RP Bills, BG (reprint author), NASA, Geodynam Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM bbills@igpp.ucsd.edu; james@pgc.nrcan.gc.ca; mengel@mite.gsfc.nasa.gov RI Bills, Bruce/C-1156-2008; James, Thomas/D-9301-2013 OI James, Thomas/0000-0001-7321-047X NR 73 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD JAN 10 PY 1999 VL 104 IS B1 BP 1059 EP 1075 DI 10.1029/1998JB900004 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 159FV UT WOS:000078162100028 ER PT J AU Glazman, RE Cheng, B AF Glazman, RE Cheng, B TI Altimeter observations of baroclinic oceanic inertia-gravity wave turbulence SO PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article DE nonlinear waves; internal waves; baroclinic tide; wave turbulence spectra; ocean remote sensing; satellite altimetry ID BRUNT-VAISALA FREQUENCY; MESOSCALE VARIABILITY; NORTH-ATLANTIC; SHALLOW-WATER; ROSSBY RADII; GENERATION; SPECTRA; SEA AB For a wide range of nonlinear wave processes, from capillary to planetary waves, theory has yielded simple analytical expressions for wave spectra controlled by Kolmogorov-type spectral cascades of energy and other conserved quantities. However, observations of wave turbulence (WT) have been limited to small-scale processes such as surface gravity and capillary-gravity waves. Presently, sea-surface height measurements by the Topex/Poseidon altimeter allow one to detect WT with spatial scales from about 50 km to 1000 km, occurring in baroclinic inertia-gravity (IG) waves. The characteristic amplitude of sea-surface height oscillations is about 5 cm, which means that the internal wave amplitude may attain a few tens of metres. Similar to the case of acoustic waves generated by three-dimensional turbulence, IG waves are most intense in regions of a large horizontal velocity shear near major ocean currents, where the level of two-dimensional eddy turbulence is high. The degree of the IG wave nonlinearity in such regions is well above the weak-turbulence limit (of four-wave resonant interactions). The IG and vortical motions are analysed using a recently developed technique of altimeter data analysis, which exploits the great difference in the intrinsic time-scales of these two basic types of oceanic motion. Scattering of barotropic tide by ocean-floor topography provides another mechanism of baroclinic IG WT which has important implications for global dissipation of tidal energy. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Glazman, RE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 39 TC 7 Z9 7 U1 0 U2 2 PU ROYAL SOC PI LONDON PA 6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-5021 EI 1471-2946 J9 P ROY SOC A-MATH PHY JI Proc. R. Soc. A-Math. Phys. Eng. Sci. PD JAN 8 PY 1999 VL 455 IS 1981 BP 91 EP 123 PG 33 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 162KN UT WOS:000078345600004 ER PT J AU Hurley, K Cline, T Mazets, E Barthelmy, S Butterworth, P Marshall, F Palmer, D Aptekar, R Golenetskii, S Il'Inskii, V Frederiks, D McTiernan, J Gold, R Trombka, J AF Hurley, K Cline, T Mazets, E Barthelmy, S Butterworth, P Marshall, F Palmer, D Aptekar, R Golenetskii, S Il'Inskii, V Frederiks, D McTiernan, J Gold, R Trombka, J TI A giant periodic flare from the soft gamma-ray repeater SGR1900+14 SO NATURE LA English DT Article ID 1979 MARCH 5; BURST; TRANSIENT; LOCATION; EVENT AB Soft gamma-ray repeaters are transient sources of high-energy photons; they emit sporadic and short (about 0.1 s) bursts of 'soft' gamma-rays during periods of activity which are often broken by long stretches of quiescence. These objects are associated with neutron stars in young supernova remnants(1). The event of 5 March 1979 was the most intense burst to date, and the only one that showed a dear periodicity in the signal(2,3). Here we report the detection, on 27 August 1998, of an even more intense burst from a different soft gamma-ray repeater. This event was characterized by 'hard' gamma-rays at its peak, followed by a tail 300 s long with a soft spectrum and a dear periodicity of 5.16 s. The burst was probably initiated by a massive disruption of the crust of the neutron star, followed by an outflow of energetic particles rotating with the period of the star. A comparison of the events of 27 August 1998 and 5 March 1979 supports the idea that magnetic energy plays an important role in the genesis of such events. Although these giant hares are rare, they are not unique events and may occur at any time in a neutron star's activity cycle. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RP Hurley, K (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI Barthelmy, Scott/D-2943-2012; Frederiks, Dmitry/C-7612-2014; Aptekar, Raphail/B-3456-2015; Golenetskii, Sergey/B-3818-2015; OI Frederiks, Dmitry/0000-0002-1153-6340 NR 28 TC 269 Z9 270 U1 0 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 7 PY 1999 VL 397 IS 6714 BP 41 EP 43 DI 10.1038/16199 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 155RD UT WOS:000077959400039 ER PT J AU Van Keuls, FW Romanofsky, RR Varaljay, ND Miranda, FA Canedy, CL Aggarwal, S Venkatesan, T Ramesh, R AF Van Keuls, FW Romanofsky, RR Varaljay, ND Miranda, FA Canedy, CL Aggarwal, S Venkatesan, T Ramesh, R TI A Ku-band gold BaxSr1-xTiO3/LaAIO(3) conductor thin-film ferroelectric microstrip line phase shifter for room-temperature communications applications SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE thin-film ferroelectric; coupled microstrip; phase shifter; Ku-band; room temperature AB We report on the performance of a Ku-band gold/ Ba0.5Sr0.5TiO3/LnAlO(3) (Au/BSTO/LAO) coupled microstip line phase shifter fabricated with a 370 nm thick BSTO film. Two hundred degrees of contiguous relative insertion phase shift (Delta phi(S21)) with insertion losses of 4.6 dB, were measured at room temperature, 14.3 GHz, and maximum de voltage of 400 V. These results represent significant progress toward viable compact, low-loss, thin-film ferroelectric-based phase shifters nr room temperature. (C) 1999 John Whey & Sons, Inc. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Univ Maryland, College Pk, MD 20742 USA. RP Van Keuls, FW (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RI Venkatesan, Thirumalai/E-1667-2013 NR 6 TC 35 Z9 36 U1 0 U2 3 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD JAN 5 PY 1999 VL 20 IS 1 BP 53 EP 56 DI 10.1002/(SICI)1098-2760(19990105)20:1<53::AID-MOP15>3.0.CO;2-L PG 4 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA 147YU UT WOS:000077487900015 ER PT B AU Hubeny, I Barstow, MA Lanz, T Holberg, JB AF Hubeny, I Barstow, MA Lanz, T Holberg, JB BE Solheim, JE Meistas, EG TI Non-LTE model atmospheres of hot DA white dwarfs SO 11TH EUROPEAN WORKSHOP ON WHITE DWARFS SE Astronomical Society of the Pacific Conference Series LA English DT Proceedings Paper CT 11th European Workshop on White Dwarfs CY JUN 29-JUL 03, 1998 CL TROMSO, NORWAY SP Astron Soc Pacific ID STELLAR ATMOSPHERES; ELEMENTS AB A brief review of the recent developments in model atmospheres for hot metal-rich DA white dwarfs is presented. The most significant development is a routine computation of fully metal-line-blanketed model atmospheres, where some 10 million lines of several ions of Fe and Ni are taken into account in non-LTE, and where inhomogeneous chemical abundances of selected species are allowed for. We have used the latest non-LTE model atmospheres to evaluate the potential effect of the presence of heavy elements in the photospheres of hot H-rich DA white dwarfs on the effective temperature and surface gravity determined from analysis of the Balmer line profiles. We have demonstrated that both the inclusion of non-LTE effects in the models and significant quantities of heavy elements separately lower the value of T(eff) determined from a particular spectrum. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hubeny, I (reprint author), NASA, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. EM hubeny@tlusty.gsfc.nasa.gov; mab@star.le.ac.uk; holberg@argus.lpl.arizona.edu NR 16 TC 3 Z9 3 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-91-0 J9 ASTR SOC P PY 1999 VL 169 BP 445 EP 450 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN45D UT WOS:000081943400069 ER PT B AU Chao, WC AF Chao, WC GP AMS AMS TI On the origin of monsoon onset SO 12TH CONFERENCE ON ATMOSPHERIC AND OCEANIC FLUID DYNAMICS LA English DT Proceedings Paper CT 12th Conference on Atmospheric and Oceanic Fluid Dynamics CY JUN 07-11, 1999 CL NEW YORK, NY SP Amer Meteorol Soc, Columbia Univ Earth Inst ID HADLEY CIRCULATION; CONVECTION; NORTH; ITCZ C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Chao, WC (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. EM winston.chao@gfsc.nasa.gov NR 15 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 1999 BP 157 EP 160 PG 4 WC Mechanics; Meteorology & Atmospheric Sciences; Oceanography; Physics, Fluids & Plasmas SC Mechanics; Meteorology & Atmospheric Sciences; Oceanography; Physics GA BS05G UT WOS:000168477900049 ER PT B AU Chou, SH AF Chou, SH GP AMS AMS TI Wavenumber vacillation in weakly-stratified baroclinic flows SO 12TH CONFERENCE ON ATMOSPHERIC AND OCEANIC FLUID DYNAMICS LA English DT Proceedings Paper CT 12th Conference on Atmospheric and Oceanic Fluid Dynamics CY JUN 07-11, 1999 CL NEW YORK, NY SP Amer Meteorol Soc, Columbia Univ Earth Inst C1 NASA, George C Marshall Space Flight Ctr, Earth Syst Sci Off, Huntsville, AL 35812 USA. RP NASA, George C Marshall Space Flight Ctr, Earth Syst Sci Off, Huntsville, AL 35812 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 1999 BP 242 EP 244 PG 3 WC Mechanics; Meteorology & Atmospheric Sciences; Oceanography; Physics, Fluids & Plasmas SC Mechanics; Meteorology & Atmospheric Sciences; Oceanography; Physics GA BS05G UT WOS:000168477900072 ER PT S AU Flowers, BJ Needleman, HC AF Flowers, BJ Needleman, HC BE KaldeichSchurmann, B TI An overview of the NASA Sounding Rockets and Balloon Programs SO 14TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 14th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 31-JUN 03, 1999 CL POTSDAM, GERMANY SP European Space Agency, German Aerosp Ctr AB The (NASA) Sounding Rockets and Balloon Programs conduct a total of 50 to 60 missions per year in support of the NASA scientific community. These missions support investigations sponsored by NASA's Offices of Space Science, Life and Microgravity Sciences & Applications, and Earth Science. The Goddard Space Flight Center has management and implementation responsibility for these programs. The NASA Sounding Rockets Program supports the science community by integrating their experiments into the sounding rocket payload, providing the rocket vehicle and launch operations. Sounding rockets continue to provide a cost-effective way to make in situ observations from 50 to 1500 km in the near-earth environment and uniquely cover the altitude regime between 50 km and 130 km above the Earth's surface. The NASA Balloon Program continues to make advancements and developments in its capabilities for support of the scientific ballooning community. The Long Duration Balloon (LDB) is a prominent aspect of the program with two campaigns scheduled for this calendar year. NASA has initiated an Ultra Long Duration Balloon project (ULDB) for the development of a 100-day duration balloon capability. The Program has also continued to introduce new technology and improvements into flights systems, ground systems and operational techniques. C1 NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Sounding Rocket Program Off, Wallops Island, VA 23337 USA. RP Flowers, BJ (reprint author), NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Sounding Rocket Program Off, Wallops Island, VA 23337 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-748-8 J9 ESA SP PUBL PY 1999 VL 437 BP 65 EP 72 PG 8 WC Engineering, Aerospace; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA BP31E UT WOS:000084659100007 ER PT S AU Schmidlin, FJ AF Schmidlin, FJ BE KaldeichSchurmann, B TI Temperature variability associated with the Middle Atmosphere Electrodynamics (MAE-1) Campaign SO 14TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 14th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 31-JUN 03, 1999 CL POTSDAM, GERMANY SP European Space Agency, German Aerosp Ctr AB Meteorological rockets launched during the Middle Atmosphere Electrodynamics (MAE-1) Campaign in October 1980 from Andoya Rochet Range (ARR), Norway, exhibited large and unexpected temperature variability. Temperatures varied up to 18 degrees C within a few hours and also demonstrated a similar type of variability over a three-day period. Whether the variability was due to natural atmospheric causes or instrument malfunction is to be determined. Small-scale variability, as observed, may have resulted from one or multiple sources, e.g., intense storms upstream from the observing site, orography such as mountain waves generated from the Greenland Plateau, convective activity, gravity waves, etc. Spacing the observations with respect to time showed perturbations moving downward. We discuss the errors of the rocketsonde measurements, graphically review the nature of the variability observed, compare the data with other measurements, and postulate a possible cause for the variability. C1 NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Island, VA 23337 USA. RP Schmidlin, FJ (reprint author), NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Island, VA 23337 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-748-8 J9 ESA SP PUBL PY 1999 VL 437 BP 269 EP 274 PG 6 WC Engineering, Aerospace; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA BP31E UT WOS:000084659100039 ER PT S AU Schmidlin, FJ Goldberg, RA AF Schmidlin, FJ Goldberg, RA BE KaldeichSchurmann, B TI Meteorological measurements for the scientific study of the mesosphere during MALTED/GUARA SO 14TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 14th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 31-JUN 03, 1999 CL POTSDAM, GERMANY SP European Space Agency, German Aerosp Ctr ID CADRE/MALTED CAMPAIGN; SATELLITE; ROCKET; RADAR AB The rocket-borne falling sphere technique provided collaborative temperature and wind measurements as part of the electrodynamics campaign MALTED/GUARA conducted in Brazil during 1994. The falling sphere method is well known. The vertical resolution of the data resulting from the smoothing filters used and the time/height sections characterizing temperature and wind structure are examined. Ten days of measurements including two days of more intensive measurements, were obtained. In addition to the electrodynamics requirement, small- and large-scale motions were of interest. A brief discussion is given describing the observed structure. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Schmidlin, FJ (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Goldberg, Richard /E-1881-2012 NR 4 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-748-8 J9 ESA SP PUBL PY 1999 VL 437 BP 405 EP 410 PG 6 WC Engineering, Aerospace; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA BP31E UT WOS:000084659100063 ER PT S AU Croll, A Schweizer, M Dold, P Kaiser, T Benz, KW Lichtensteiger, M AF Croll, A Schweizer, M Dold, P Kaiser, T Benz, KW Lichtensteiger, M BE KaldeichSchurmann, B TI Measurement of temperature fluctuations and microscopic growth rates in a silicon floating zone on TEXUS36 SO 14TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 14th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 31-JUN 03, 1999 CL POTSDAM, GERMANY SP European Space Agency, German Aerosp Ctr DE floating-zone; thermocapillary convection; temperature fluctuations; growth rate fluctuations; silicon ID MAGNETIC-FIELDS; MICROGRAVITY AB Several earlier mu g experiments have shown that time-dependent thermocapillary (Marangoni) convection is the major cause for the formation of dopant striations in floating-zone grown semiconductor crystals, at least in small-scale systems not employing RF heating. To quantify this correlation, a silicon floating-zone experiment was performed on the TEXUS36 flight (February 7, 1998) in the monoellipsoid mirror furnace TEM02-ELLI. During the experiment, temperature fluctuations in the silicon melt zone and the microscopic growth rate were simultaneously measured. Temperature fluctuations of 0.5 degrees C - 0.7 degrees C with main frequencies between 0.1Hz and 0.3Hz were detectable. The microscopic growth rate fluctuated considerably around the average growth rate of 1mm/min: rates from 4mm/min to negative values (backmelting) were observed. Dopant striations are clearly visible in the Sb-doped crystal. The frequencies associated with the dopant inhomogeneities correspond quite well with those of the temperature fluctuations and microscopic growth rates. 3D numerical simulations were performed to predict the optimum position of the temperature sensor, to evaluate characteristic temperature amplitudes and frequencies, and to give insight into the instability mechanisms of Marangoni convection in this configuration. The simulations were in good agreement with the experimental values, showing temperature fluctuations with frequencies f less than or equal to 0.25Hz and amplitudes up to 1.8 degrees C at a position equivalent to that of the sensor tip in the experiment. C1 Univ Alabama, AMMSA, NASA, MSFC, Huntsville, AL 35812 USA. RP Croll, A (reprint author), Univ Alabama, AMMSA, NASA, MSFC, SD47, Huntsville, AL 35812 USA. RI Croell, Arne/A-2480-2013 OI Croell, Arne/0000-0002-8673-9994 NR 17 TC 0 Z9 0 U1 0 U2 1 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-748-8 J9 ESA SP PUBL PY 1999 VL 437 BP 529 EP 534 PG 6 WC Engineering, Aerospace; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA BP31E UT WOS:000084659100083 ER PT S AU Silverberg, RF AF Silverberg, RF CA MSAM TopHat Collaboration BE KaldeichSchurmann, B TI The topHat Cosmic Microwave Background anisotropy experiment SO 14TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 14th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 31-JUN 03, 1999 CL POTSDAM, GERMANY SP European Space Agency, German Aerosp Ctr DE cosmology; Cosmic Microwave Background; ballooning; large scale structure ID MEDIUM-SCALE ANISOTROPY AB We have developed a balloon-borne experiment to measure the Cosmic Microwave Background Radiation anisotropy on angular scales from similar to 50 degrees down to similar to 20'. The instrument observes at frequencies between 150 and 690 GHz and will be flown on an Antarctic circumpolar long duration flight. To greatly improve the experiment performance, the front-end of the experiment is mounted on the tap of the balloon. With high sensitivity, broad sky coverage, and well-characterized systematic errors, the results of this experiment can be used to strongly constrain cosmological models and probe the early stages of large-scale structure formation in the Universe. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Silverberg, RF (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-748-8 J9 ESA SP PUBL PY 1999 VL 437 BP 599 EP 602 PG 4 WC Engineering, Aerospace; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA BP31E UT WOS:000084659100089 ER PT S AU Wilson, E Mah, R AF Wilson, E Mah, R GP SPIE SPIE TI On-line fringe tracking and prediction at IOTA SO 18TH CONGRESS OF THE INTERNATIONAL COMMISSION FOR OPTICS: OPTICS FOR THE NEXT MILLENNIUM, TECHNICAL DIGEST SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 18th Congress of the International Commission for Optics - Optics for the Next Millennium CY AUG 02-06, 1999 CL SAN FRANCISCO, CA SP SPIE, Amer Physical Soc, IEEE Lasers & electro Optics Soc, OSA Optical Soc Amer, Int Comm Optics, US Advisory Comm Int Commiss Opt AB The Infrared/Optical Telescope Array (IOTA) is a multi-aperture Michelson interferometer located on Mt. Hopkins near Tucson, Arizona. To enable viewing of fainter targets, an on-line fringe tracking system is presently under development at NASA Ames Research Center. The system has been developed off-line using actual data from IOTA, and is presently undergoing on-line implementation at IOTA. The system has two parts: (1) a fringe tracking system that identifies the center of a fringe packet by fitting a parametric model to the data; and (2) a fringe packet motion prediction system that uses characteristics of past fringe packets to predict fringe packet motion. Combined, this information will be used to optimize online the scanning trajectory, resulting in improved visibility of faint targets. Fringe packet identification is highly accurate and robust (99% of the 4000 fringe packets were identified correctly, the remaining 1% were either out of the scan range or too noisy to be seen) and is performed in 30-90 milliseconds (depending on desired accuracy) on a Pentium II-based computer. Fringe packet prediction, currently performed using an adaptive linear predictor, delivers a 10% improvement over the baseline of predicting no motion. C1 NASA, Ames Res Ctr, Smart Syst Lab, Informat Sci Div, Moffett Field, CA 94035 USA. RP Wilson, E (reprint author), NASA, Ames Res Ctr, Smart Syst Lab, Informat Sci Div, MS 269-1, Moffett Field, CA 94035 USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3234-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3749 BP 691 EP 692 DI 10.1117/12.354958 PG 2 WC Optics SC Optics GA BN74Q UT WOS:000082790200310 ER PT B AU Tunstel, E AF Tunstel, E BE Dave, RN Sudkamp, T TI Fuzzy behavior modulation with threshold activation for autonomous vehicle navigation SO 18TH INTERNATIONAL CONFERENCE OF THE NORTH AMERICAN FUZZY INFORMATION PROCESSING SOCIETY - NAFIPS LA English DT Proceedings Paper CT 18th International Conference of the North-American-Fuzzy-Information-Processing-Society (NAFIPS 99) CY JUN 10-12, 1999 CL NEW YORK, NY SP N Amer Fuzzy Informat Proc Soc, IEEE Neural Networks Council, IEEE Syst Man & Cybernet Soc AB This paper describes fuzzy logic techniques used in a hierarchical behavior-based architecture for robot navigation. An architectural feature for threshold activation of fuzzy behaviors is emphasized, which is potentially useful for tuning navigation performance in real world applications. The target application is autonomous local navigation of a small planetary rover. Threshold activation of low-level navigation behaviors is the primary focus. A preliminary assessment of its impact on local navigation performance is provided based on computer simulations. C1 CALTECH, Jet Prop Lab, Robot Vehicles Grp, Pasadena, CA 91109 USA. RP Tunstel, E (reprint author), CALTECH, Jet Prop Lab, Robot Vehicles Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 3 Z9 3 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5211-4 PY 1999 BP 776 EP 780 DI 10.1109/NAFIPS.1999.781799 PG 5 WC Computer Science, Artificial Intelligence; Computer Science, Interdisciplinary Applications SC Computer Science GA BN34H UT WOS:000081666600160 ER PT S AU Wilson, WJ Njoku, EG AF Wilson, WJ Njoku, EG BE Matloubian, M Ponti, E TI Future radiometer systems for earth remote sensing SO 1999 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-4 SE IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST LA English DT Proceedings Paper CT 1999 IEEE MTT-S International Microwave Symposium on the Magic Touch of Microwaves CY JUN 13-19, 1999 CL ANAHEIM, CA SP IEEE AB This paper will describe a new exciting concept for using microwave systems for Earth remote sensing. This concept will use a 6-m diameter mesh deployable antenna with active and passive systems to provide moderate spatial resolution images at L and S-band microwave frequencies. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wilson, WJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Bldg 168-327, Pasadena, CA 91109 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 0149-645X BN 0-7803-5135-5 J9 IEEE MTT-S PY 1999 BP 395 EP 398 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BN28P UT WOS:000081428500091 ER PT S AU Le Vine, DM AF Le Vine, DM BE Matloubian, M Ponti, E TI Synthetic aperture radiometer systems SO 1999 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-4 SE IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST LA English DT Proceedings Paper CT 1999 IEEE MTT-S International Microwave Symposium on the Magic Touch of Microwaves CY JUN 13-19, 1999 CL ANAHEIM, CA SP IEEE ID MICROWAVE RADIOMETER AB Aperture synthesis is an emerging technology for passive microwave remote sensing from space. It is an interferometric technique in which pairs of small antennas and signal processing are used to obtain the resolution of a single large antenna. The technique has been demonstrated successfully at L-band with the aircraft prototype, ESTAR; and proposals have been submitted to demonstrate this technology in space. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Le Vine, DM (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 0149-645X BN 0-7803-5135-5 J9 IEEE MTT-S PY 1999 BP 407 EP 410 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BN28P UT WOS:000081428500094 ER PT S AU Van Keuls, FW Mueller, CH Miranda, FA Romanofsky, RR Canedy, CL Aggarwal, S Venkatesan, T Ramesh, R Horwitz, JS Chang, W Kim, WJ AF Van Keuls, FW Mueller, CH Miranda, FA Romanofsky, RR Canedy, CL Aggarwal, S Venkatesan, T Ramesh, R Horwitz, JS Chang, W Kim, WJ BE Matloubian, M Ponti, E TI Room temperature thin film BaxSr1-xTiO3 Ku-band coupled microstrip phase shifters: Effects of film thickness, doping, annealing and substrate choice SO 1999 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-4 SE IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST LA English DT Proceedings Paper CT 1999 IEEE MTT-S International Microwave Symposium on the Magic Touch of Microwaves CY JUN 13-19, 1999 CL ANAHEIM, CA SP IEEE AB We report on measurements taken on thirteen Ku-band coupled microstrip phase shifters (CMPS) using thin ferroelectric films of BaxSr1-xTiO3. This CMPS design is a recent innovation designed to take advantage of the high tunability and tolerate the high dielectric constant of ferroelectric films at Ku- and K-band frequencies. These devices are envisioned as a component in low-cost steerable beam phased array antennas. Comparisons are made between devices with differing film thickness, annealed vs. unannealed, Mn-doped, vs. undoped, and also substrates of LaAlO3 and MgO. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Van Keuls, FW (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RI Venkatesan, Thirumalai/E-1667-2013 NR 7 TC 12 Z9 12 U1 0 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 0149-645X BN 0-7803-5135-5 J9 IEEE MTT-S PY 1999 BP 737 EP 740 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BN28P UT WOS:000081428500169 ER PT S AU Kwok, RS Fiedziuszko, SJ Schnabel, T Miranda, FA Varaljay, NC Mueller, C AF Kwok, RS Fiedziuszko, SJ Schnabel, T Miranda, FA Varaljay, NC Mueller, C BE Matloubian, M Ponti, E TI Low-profile multilayer YBCO MgO filter module SO 1999 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-4 SE IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST LA English DT Proceedings Paper CT 1999 IEEE MTT-S International Microwave Symposium on the Magic Touch of Microwaves CY JUN 13-19, 1999 CL ANAHEIM, CA SP IEEE ID MODE AB Multilayer dual mode HTS filter is the smallest known high-performance filter structure, occupies less than 1% in volume as compared to the state-of-the-art dielectric resonator counterpart. It can also be manufactured in form Of a flat-pack surface mounted flip-chip module suitable for integration with other components in a cryogenic payload. In this presentation, we report recent advances made in the areas of design and packaging of this vertically stacked multilayer filter. A C-band 4-pole quasi-elliptical bandpass filter in its smallest configuration, implemented using either gold (Au) or YBCO thin film dual mode patch resonators on magnesium oxide (MgO) substrates, will be presented. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Kwok, RS (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 0149-645X BN 0-7803-5135-5 J9 IEEE MTT-S PY 1999 BP 1377 EP 1380 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BN28P UT WOS:000081428500317 ER PT S AU Ponchak, GE Akinwande, D Ciocan, R LeClair, SR Tabib-Azar, M AF Ponchak, GE Akinwande, D Ciocan, R LeClair, SR Tabib-Azar, M BE Matloubian, M Ponti, E TI Evanescent microwave probes using coplanar waveguide and stripline for super-resolution imaging of materials SO 1999 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-4 SE IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST LA English DT Proceedings Paper CT 1999 IEEE MTT-S International Microwave Symposium on the Magic Touch of Microwaves CY JUN 13-19, 1999 CL ANAHEIM, CA SP IEEE ID MICROSCOPE AB An evanescent field microwave imaging probe based on half-wavelength, microwave transmission line resonators is described. Optimization of the probe tip design, the coupling gap, and the data analysis has resulted in images of metal lines on semiconductor substrates with 2.6 mu m spatial resolution and a minimum detectable line width of 0.4 mu m at 1 GHz. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Ponchak, GE (reprint author), NASA, Lewis Res Ctr, 21000 Brookpk Rd,MS 54-5, Cleveland, OH 44135 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 0149-645X BN 0-7803-5135-5 J9 IEEE MTT-S PY 1999 BP 1859 EP 1862 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BN28P UT WOS:000081428500427 ER PT S AU Sherrit, S Dolgin, BP Bar-Cohen, Y Pal, D Kroh, J Peterson, T AF Sherrit, S Dolgin, BP Bar-Cohen, Y Pal, D Kroh, J Peterson, T BE Schneider, SC Levy, M McAvoy, BR TI Modeling of horns for sonic/ultrasonic applications SO 1999 IEEE ULTRASONICS SYMPOSIUM PROCEEDINGS, VOLS 1 AND 2 SE ULTRASONICS SYMPOSIUM LA English DT Proceedings Paper CT 1999 IEEE Ultrasonics International Symposium CY OCT 17-20, 1999 CL TAHOE, NV SP IEEE Ultrason Ferroelect & Frequency Control Soc AB JPL has a requirement for telerobotic tools for planetary sample acquisition, which require low power and have the ability to work in harsh environments. We are currently investigating the possibility of using ultrasonic horns to develop a family of ultrasonic tools for these environments. In an effort to determine control parameters a one-dimensional Mason's model for a stepped ultrasonic horn assembly was developed which includes the effects of mechanical and electrica losses in the piezoelectric material and acoustic elements. The model is separated into three regions; the piezoelectric stack including stress bolt the backing layer and the horn. The model is found to predict the impedance data of the horn assembly very accurately up to the first coupled (radial) resonance. The model also allows for the calculation of the velocity and force and power delivered to each acoustic element. FEM modeling and accelerometer data from the horn tip were used to corroborate the model. The difficulties associated with modeling the load impedance of various devices will be discussed and current directions noted. developed electrical elements. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Sherrit, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 8 TC 10 Z9 10 U1 0 U2 3 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1051-0117 BN 0-7803-5723-X J9 ULTRASON PY 1999 BP 647 EP 651 PG 5 WC Acoustics; Instruments & Instrumentation; Physics, Applied SC Acoustics; Instruments & Instrumentation; Physics GA BQ43A UT WOS:000088356000139 ER PT S AU Oeftering, R AF Oeftering, R BE Schneider, SC Levy, M McAvoy, BR TI Acoustic liquid manipulation SO 1999 IEEE ULTRASONICS SYMPOSIUM PROCEEDINGS, VOLS 1 AND 2 SE ULTRASONICS SYMPOSIUM LA English DT Proceedings Paper CT 1999 IEEE Ultrasonics International Symposium CY OCT 17-20, 1999 CL TAHOE, NV SP IEEE Ultrason Ferroelect & Frequency Control Soc AB Acoustic Liquid Manipulation (ALM) is a term coined to describe the use of non-linear acoustics to move liquid, manipulate liquid surfaces, and propel buoyant objects. It differs from acoustic levitation because it does not rely on standing waves but instead uses focused directed beams operating at RF frequencies, employs burst modulation and transmits through liquids. Transducers with simple focusing lenses were employed initially but now the emphasis is on acoustic phased arrays. Applications both real and contemplated involve the acoustic dispensing of droplets from needles, ejection of droplets from free surface pools, and acoustic manipulation of free surfaces, bubbles and objects. NASA is evaluating these techniques for a variety of multiphase fluid systems including space experiments and systems for the Space Station. Meanwhile, ground manufacturing applications range from PC board electronics to micro-electronic and micro-machine scale devices. ALM is already being developed to reduce or eliminate masks in plating and etching operations, which, in turn, reduces waste products. C1 NASA, Gless Res Ctr, Cleveland, OH 44135 USA. RP Oeftering, R (reprint author), NASA, Gless Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 6 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1051-0117 BN 0-7803-5723-X J9 ULTRASON PY 1999 BP 675 EP 678 PG 4 WC Acoustics; Instruments & Instrumentation; Physics, Applied SC Acoustics; Instruments & Instrumentation; Physics GA BQ43A UT WOS:000088356000145 ER PT S AU Anastasi, RF Madaras, EI AF Anastasi, RF Madaras, EI BE Schneider, SC Levy, M McAvoy, BR TI Pulse compression techniques for laser generated ultrasound SO 1999 IEEE ULTRASONICS SYMPOSIUM PROCEEDINGS, VOLS 1 AND 2 SE ULTRASONICS SYMPOSIUM LA English DT Proceedings Paper CT 1999 IEEE Ultrasonics International Symposium CY OCT 17-20, 1999 CL TAHOE, NV SP IEEE Ultrason Ferroelect & Frequency Control Soc AB Laser generated ultrasound for nondestructive evaluation has an optical power density limit due to rapid high heating that causes material damage. This damage threshold limits the generated ultrasound amplitude, which impacts nondestructive evaluation inspection capability. To increase ultrasound signal levels and improve the ultrasound signal-to-noise ratio without exceeding laser power limitations, it is possible to use pulse compression techniques. The approach illustrated here uses a 150mW laser-diode modulated with a pseudo-random sequence and signal correlation. Results demonstrate the successful generation of ultrasonic bulk waves in aluminum and graphite-epoxy composite materials using a modulated low-power laser diode and illustrate ultrasound bandwidth control. C1 NASA, Langley Res Ctr, USA,Vehicle Technol Directorate, ARL,AMSRL VT S,Nondestruct Evaluat Sci Branch, Hampton, VA 23681 USA. RP Anastasi, RF (reprint author), NASA, Langley Res Ctr, USA,Vehicle Technol Directorate, ARL,AMSRL VT S,Nondestruct Evaluat Sci Branch, Hampton, VA 23681 USA. NR 20 TC 1 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1051-0117 BN 0-7803-5723-X J9 ULTRASON PY 1999 BP 813 EP 817 PG 5 WC Acoustics; Instruments & Instrumentation; Physics, Applied SC Acoustics; Instruments & Instrumentation; Physics GA BQ43A UT WOS:000088356000175 ER PT S AU Sherrit, S Leary, SP Dolgin, BP Bar-Cohen, Y AF Sherrit, S Leary, SP Dolgin, BP Bar-Cohen, Y BE Schneider, SC Levy, M McAvoy, BR TI Comparison of the Mason and KLM equivalent circuits for piezoelectric resonators in the thickness mode SO 1999 IEEE ULTRASONICS SYMPOSIUM PROCEEDINGS, VOLS 1 AND 2 SE ULTRASONICS SYMPOSIUM LA English DT Proceedings Paper CT 1999 IEEE Ultrasonics International Symposium CY OCT 17-20, 1999 CL TAHOE, NV SP IEEE Ultrason Ferroelect & Frequency Control Soc ID TRANSDUCERS; CERAMICS AB The parameters of the KLM and Mason's equivalent circuits in the thickness mode are presented to include dielectric, elastic and piezoelectric loss. The models are compared under various boundary conditions with and without acoustic layers to the analytical solutions of the wave equation. We show that in ail cases equivalence is found between the analytical solution and the KLM and Mason's equivalent circuit models. It is noted that in order to maintain consistency with the linear equations of piezoelectricity and the wave equation care is required when applying complex coefficients to the models. The effect of the piezoelectric loss component on the power dissipated in the transducer is presented for loaded and unloaded transducers to determine the significance of the piezoelectric loss to transducer designers. The effect of the piezoelectric loss on the insertion loss was found to be small. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Sherrit, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 20 TC 18 Z9 19 U1 3 U2 10 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1051-0117 BN 0-7803-5723-X J9 ULTRASON PY 1999 BP 921 EP 926 PG 6 WC Acoustics; Instruments & Instrumentation; Physics, Applied SC Acoustics; Instruments & Instrumentation; Physics GA BQ43A UT WOS:000088356000197 ER PT S AU Boyce, L Bolotin, G AF Boyce, L Bolotin, G GP INT MICROELECTR & PACKAGING SOC INT MICROELECTR & PACKAGING SOC TI An adaptive method for reducing clock skew in an accumulative z-axis interconnect system SO 1999 INTERNATIONAL CONFERENCE ON HIGH DENSITY PACKAGING AND MCMS, PROCEEDINGS SE Proceedings of SPIE LA English DT Proceedings Paper CT 1999 International Conference on High Density Packaging and MCMs CY APR 06-09, 1999 CL DENVER, CO SP Int Microelectr & Packaging Soc AB This paper will present several methods for adjusting clock skew variations that occur in an accumulative z-axis interconnect system. In such a system, delay between modules is a function of their distance from one another. Clock distribution in a high-speed system, where clock skew must be kept to a minimum, becomes more challenging when module order is variable before design. C1 NASA, Jet Propuls Lab, Pasadena, CA 91109 USA. RP NASA, Jet Propuls Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM lee.boyce@jpl.nasa.gov; gary.s.bolotin@jpl.nasa.gov NR 5 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-930815-57-2 J9 PROC SPIE PY 1999 VL 3830 BP 70 EP 73 PG 4 WC Computer Science, Hardware & Architecture; Computer Science, Information Systems; Engineering, Electrical & Electronic; Optics; Telecommunications SC Computer Science; Engineering; Optics; Telecommunications GA BN66B UT WOS:000082520700012 ER PT S AU Hunter, DJ AF Hunter, DJ GP INT MICROELECTR & PACKAGING SOC INT MICROELECTR & PACKAGING SOC TI Integrated Avionics System (IAS), integrating 3-D technology on a spacecraft panel SO 1999 INTERNATIONAL CONFERENCE ON HIGH DENSITY PACKAGING AND MCMS, PROCEEDINGS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 1999 International Conference on High Density Packaging and MCMs CY APR 06-09, 1999 CL DENVER, CO SP Int Microelectr & Packaging Soc AB As spacecraft designs converge toward miniaturization, and with the volumetric and mass challenges placed on avionics, programs will continue to advance the "state of the art" in spacecraft system development with new challenges to reduce power, mass and volume. Traditionally, the trend is to focus on high-density 3-D packaging technologies. Industry has made significant progress in 3-D technologies, and other related internal and external interconnection schemes. Although new technologies have improved packaging densities, a system packaging architecture is required that not only reduces spacecraft volume and mass budgets, but increase integration efficiencies, provide modularity and flexibility to accommodate multiple missions while maintaining a low recurring cost. With these challenges in mind, a novel system packaging approach incorporates solutions that provide broader environmental applications, more flexible system interconnectivity, scalability, and simplified assembly rest and integration schemes. The Integrated Avionics System (IAS) provides for a low-mass, modular distributed or centralized packaging architecture which combines ridged-flex technologies, high-density COTS hardware and a new 3-D mechanical packaging approach, Horizontal Mounted Cube (HMC). This paper will describe the fundamental elements of the LAS, HMC hardware design, system integration and environmental test results. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hunter, DJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-930815-57-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3830 BP 80 EP 84 PG 5 WC Computer Science, Hardware & Architecture; Computer Science, Information Systems; Engineering, Electrical & Electronic; Optics; Telecommunications SC Computer Science; Engineering; Optics; Telecommunications GA BN66B UT WOS:000082520700014 ER PT S AU Alkalai, L AF Alkalai, L GP INT MICROELECTR & PACKAGING SOC INT MICROELECTR & PACKAGING SOC TI Advanced packaging technologies used in NASA's 3D space Flight Computer SO 1999 INTERNATIONAL CONFERENCE ON HIGH DENSITY PACKAGING AND MCMS, PROCEEDINGS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 1999 International Conference on High Density Packaging and MCMs CY APR 06-09, 1999 CL DENVER, CO SP Int Microelectr & Packaging Soc DE 3D packaging technologies; Flight Computer; avionics AB During 1995-1997, NASA's New Millennium Program developed the 3D Flight Computer technology for validation on its first Deep-Space 1 mission launched in October 1998. Whereas, the computer was not delivered on schedule for inclusion on the spacecraft, it was delivered, integrated and space qualified at JPL. This computer is characterized by the aggressive use of advanced packaging technologies: 3D chip stacking, multichip modules and 3D MCM stacking. This development represents an important technology milestone towards the further miniaturization of all spacecraft avionics into an integrated architecture. C1 CALTECH, Jet Prop Lab, Ctr Integrated Space Microsyst, Pasadena, CA 91109 USA. RP Alkalai, L (reprint author), CALTECH, Jet Prop Lab, Ctr Integrated Space Microsyst, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-930815-57-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3830 BP 85 EP 90 PG 6 WC Computer Science, Hardware & Architecture; Computer Science, Information Systems; Engineering, Electrical & Electronic; Optics; Telecommunications SC Computer Science; Engineering; Optics; Telecommunications GA BN66B UT WOS:000082520700015 ER PT S AU Ghaffarian, R AF Ghaffarian, R GP INT MICROELECTR & PACKAGING SOC INT MICROELECTR & PACKAGING SOC TI Chip scale package integrity assessment by isothermal aging SO 1999 INTERNATIONAL CONFERENCE ON HIGH DENSITY PACKAGING AND MCMS, PROCEEDINGS SE Proceedings of SPIE LA English DT Proceedings Paper CT 1999 International Conference on High Density Packaging and MCMs CY APR 06-09, 1999 CL DENVER, CO SP Int Microelectr & Packaging Soc DE chip scale package (CSP); ball grid arrays (BGA); isothermal aging; solder ball shear force AB Many aspects of chip scale package (CSP) technology, with a focus on assembly reliability characteristics, are being investigated by the JPL-led consortia. Three types of test vehicles were considered for evaluation and currently two configurations have been built to optimize attachment processes. These test vehicles use numerous package types. To understand potential failure mechanisms of the packages, particularly solder ball attachment grid CSPs were subjected to environmental exposure. Package I/Os ranged from 40 to nearly 300. This paper presents both as assembled: up to 1,000 hours of isothermal aging sheer test results and photo micrographs, and tensile test results before and after 1, 500 cycles in the range of -30/100 degrees C for CSPs. Results will be compared to BGAs with the same isothermal aging environmental exposures. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Reza.Ghaffarian@JPL.NASA.Gov NR 3 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-930815-57-2 J9 PROC SPIE PY 1999 VL 3830 BP 163 EP 168 PG 6 WC Computer Science, Hardware & Architecture; Computer Science, Information Systems; Engineering, Electrical & Electronic; Optics; Telecommunications SC Computer Science; Engineering; Optics; Telecommunications GA BN66B UT WOS:000082520700029 ER PT B AU DeAnna, RG Roy, S Zorman, CA Mehregany, M AF DeAnna, RG Roy, S Zorman, CA Mehregany, M GP NSTI TI Modeling of SiC lateral resonant devices over a broad temperature range SO 1999 INTERNATIONAL CONFERENCE ON MODELING AND SIMULATION OF MICROSYSTEMS LA English DT Proceedings Paper CT 2nd International Conference on Modeling and Simulation of Microsystems CY APR 19-21, 1999 CL SAN JUAN, PR SP IEEE Electron Devices Soc, Motorola, TIMA CMP Lab, Los Alamos Natl Lab, Appl Computat Res Soc, Swiss Fed Inst Technol Lausanne, Int Assoc Math & Comp Modeling, Ibero Amer Sci & Technol Educ Consortium, Integrated Syst Engn, IntelliSense Corp, MEMSCAP SA, Mentor Graph Corp, Microcosm Technologies Inc, Mol Simulat Inc ID THERMAL-EXPANSION AB Finite-element analysis (FEA) modal results of 3C-SiC lateral resonant devices anchored to a Si substrate are presented as resonant frequency versus temperature. The suspended elements are etched from a 2 mum, 3C-SiC film grown at 1600 K on a 500 mum-thick, Si substrate. The analysis includes, temperature-dependent properties, shape change due to volume expansion with temperature, and thermal stress caused by differential thermal expansion of different materials. Two designs are considered: type I has anchor locations close to the geometric centroid and a small shuttle; type II has a large shuttle with anchors far from the centroid. The resonant frequency decreases approximately 3.5% over a 1000 K temperature increase for the type-I device, and behaves according to theory. The resonant frequency of the type-II device decreases by 2% over the first 400 K, then rises slightly over the remaining 600 K. This device deviates from theory because of the high thermal stress induced in the beams. The thermal stress is caused by the differential thermal expansion of the suspended element relative to the substrate. The results show that the device geometry must be properly chosen if the resonant frequency of that device will be used to calculate the temperature coefficient of Young's modulus. These results apply only to resonators of one material on a substrate of a different material. C1 NASA, Lewis Res Ctr, USA, Res Lab,Vehicle Technol Ctr, Cleveland, OH 44135 USA. RP DeAnna, RG (reprint author), NASA, Lewis Res Ctr, USA, Res Lab,Vehicle Technol Ctr, Cleveland, OH 44135 USA. NR 5 TC 1 Z9 1 U1 0 U2 1 PU COMPUTATIONAL PUBLICATIONS PI CAMBRIDGE PA PUBISHING OFFICE, 308 ONE KENDALL SQ BLDG 600, CAMBRIDGE, MA 02139 USA BN 0-9666135-4-6 PY 1999 BP 644 EP 647 PG 4 WC Engineering, Electrical & Electronic; Engineering, Mechanical; Mathematics, Applied SC Engineering; Mathematics GA BAM65 UT WOS:000222851500162 ER PT S AU Ahlf, PR Souza, K Yost, B AF Ahlf, PR Souza, K Yost, B GP ESA ESA TI NASA's gravitational biology research hardware for the International Space Station SO 2ND EUROPEAN SYMPOSIUM ON UTILISATION OF THE INTERNATIONAL SPACE STATION SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 2nd European Symposium on Utilisation of the International Space Station CY NOV 16-18, 1998 CL NOORDWIJK, NETHERLANDS SP ESA AB As part of NASA's ongoing Human Exploration and Development of Space Enterprise, the Office of Life and Microgravity Sciences and Applications has sponsored numerous investigative programs addressing the effects of gravity (or the absence of gravity) on biological systems. Results from many of these studies have shown changes in an array of biochemical and physiological processes, as well as morphological parameters in cells, plants and animals when the normal gravitational vector is altered as in the microgravity free fall of orbital space flight. These effects extend from modifications in cellular structure and physiology to changes at the organism level. In order to enable the next generation of gravitational biology research on the International Space Station, NASA is carrying out an aggressive program of research hardware development. This hardware will enable research involving a full range of specimens ranging from cells to mammals (rodents). A capability to sustain these specimens on-orbit, provide a I-g control, and allow for on-orbit manipulation such as sampling and fixation will be provided. C1 NASA Headquarters, Div Life Sci, Washington, DC 20546 USA. RP Ahlf, PR (reprint author), NASA Headquarters, Div Life Sci, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-732-1 J9 ESA SP PUBL PY 1999 VL 433 BP 411 EP 414 PG 4 WC Engineering, Aerospace; Engineering, Biomedical; Physics, Applied SC Engineering; Physics GA BM86L UT WOS:000079962200060 ER PT S AU Kaye, JA AF Kaye, JA GP ESA ESA TI NASA's plans for earth science research from the International Space Station SO 2ND EUROPEAN SYMPOSIUM ON UTILISATION OF THE INTERNATIONAL SPACE STATION SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 2nd European Symposium on Utilisation of the International Space Station CY NOV 16-18, 1998 CL NOORDWIJK, NETHERLANDS SP ESA ID EXPERIMENT-II MEASUREMENTS; STRATOSPHERIC-AEROSOL; TECHNOLOGY EXPERIMENT; SHUTTLE MISSIONS; CLIMATOLOGY; EXTINCTION; DENSITY; LITE AB The International Space Station (ISS) should provide a valuable platform for earth science research for both externally-mounted (attached) payloads and for those using the Window Observational Research Facility (WORF). The mid-inclination (51.5 degrees) orbit provides excellent coverage of the tropics and mid-latitudes, and allows for viewing the earth under a range of lighting conditions. Further, ISS makes possible the retrieval of instruments for recalibration, repair, or modification, enhancing the possibility of its use both for long-term measurements and for testing of "first-generation" instruments, especially those requiring large mass, power, and volume. Possible complications for use of ISS, especially for Earth viewing payloads, are contamination, orbital variations, lack of pointing knowledge, platform stability, and interference with clear viewing of light sources. The only payload NASA's Office of Earth Science currently has definite plans for use on ISS is the Stratospheric Aerosol and Gas Experiment (SAGE III), with launch in 2002 being probable. SAGE III measures the vertical distribution of ozone, aerosols, and other trace constituents in the atmosphere using solar and lunar occultation. Addition of a series of infrared occultation instruments to ISS for the characterization of long-term variations in the concentrations of a larger number atmospheric trace constituents beginning several years alter the SAGE III launch has been identified as a desirable possibility, although no commitment has been made for this. C1 NASA, Off Earth Sci, Washington, DC 20546 USA. RP Kaye, JA (reprint author), NASA, Off Earth Sci, Washington, DC 20546 USA. NR 27 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-732-1 J9 ESA SP PUBL PY 1999 VL 433 BP 585 EP 592 PG 8 WC Engineering, Aerospace; Engineering, Biomedical; Physics, Applied SC Engineering; Physics GA BM86L UT WOS:000079962200089 ER PT S AU Nicogossian, AE Roy, S AF Nicogossian, AE Roy, S GP ESA ESA TI Transitioning from Spacelab to the International Space Station SO 2ND EUROPEAN SYMPOSIUM ON UTILISATION OF THE INTERNATIONAL SPACE STATION SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 2nd European Symposium on Utilisation of the International Space Station CY NOV 16-18, 1998 CL NOORDWIJK, NETHERLANDS SP ESA ID MICROGRAVITY; CARTILAGE AB As assembly of the International Space Station (ISS) gets underway, we should consider the programs that have primed us to excel at ISS assembly, operations, and research. Most notably, the Spacelab program and the Shuttle-Mir program have provided us with invaluable international space research and operations experience that has largely prepared us to meet the challenges of the Station era. C1 NASA, Off Life & Micrograv Sci & Applicat, Washington, DC 20546 USA. RP Nicogossian, AE (reprint author), NASA, Off Life & Micrograv Sci & Applicat, 300 E St SW,NASA Headquarters, Washington, DC 20546 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-732-1 J9 ESA SP PUBL PY 1999 VL 433 BP 653 EP 658 PG 6 WC Engineering, Aerospace; Engineering, Biomedical; Physics, Applied SC Engineering; Physics GA BM86L UT WOS:000079962200099 ER PT S AU Clark, KI AF Clark, KI GP ESA ESA TI Views from NASA's space station chief scientist SO 2ND EUROPEAN SYMPOSIUM ON UTILISATION OF THE INTERNATIONAL SPACE STATION SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 2nd European Symposium on Utilisation of the International Space Station CY NOV 16-18, 1998 CL NOORDWIJK, NETHERLANDS SP ESA C1 NASA Headquarters, Off Space Flight, Washington, DC 20546 USA. RP Clark, KI (reprint author), NASA Headquarters, Off Space Flight, 300 E St W, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-732-1 J9 ESA SP PUBL PY 1999 VL 433 BP 669 EP 671 PG 3 WC Engineering, Aerospace; Engineering, Biomedical; Physics, Applied SC Engineering; Physics GA BM86L UT WOS:000079962200104 ER PT B AU Feather, MS Dunphy, J Rouquette, N AF Feather, MS Dunphy, J Rouquette, N GP IEEE COMP SOC IEEE COMP SOC TI Position paper for WIFT'98 SO 2ND IEEE WORKSHOP ON INDUSTRIAL STRENGTH FORMAL SPECIFICATION TECHNIQUES - PROCEEDINGS LA English DT Proceedings Paper CT 2nd IEEE Workshop on Industrial Strength Formal Specification Techniques CY OCT 21-23, 1998 CL BOCA RATON, FL SP IEEE Comp Soc, Tech Comm Complex Comp, Florida Atlantic Univ C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Feather, MS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 125-233, Pasadena, CA 91109 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-0081-1 PY 1999 BP 140 EP 141 PG 2 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA BN32Z UT WOS:000081639400019 ER PT B AU Cox, DF AF Cox, DF BE RamirezAngulo, J TI Asynchronous logic design with transition flip-flops SO 42ND MIDWEST SYMPOSIUM ON CIRCUITS AND SYSTEMS, PROCEEDINGS, VOLS 1 AND 2 LA English DT Proceedings Paper CT 42nd Midwest Symposium on Circuits and Systems CY AUG 08-11, 1999 CL NEW MEXICO STATE UNIV, CORBETT CTR, LAS CRUCES, NM SP IEEE Circuits & Syst Soc, Klipsch Sch Elect & Comp Engn HO NEW MEXICO STATE UNIV, CORBETT CTR AB Asynchronous design was given a formal design methodology by David Huffman [1] in 1954. The procedure describes a flow process that can be used to develop Karnaugh maps from which combinatorial logic gates with feedback are used to implement the asynchronous requirements. This paper will describe a formal design procedure that can Be used to implement asynchronous circuits by using D flip-flop cells. Space flight electronics should also be low power due to the limited weight of battery and solar generation systems. C1 Univ New Mexico, Ctr Microelect Res, NASA, Inst Adv Microelect, Albuquerque, NM 87106 USA. RP Cox, DF (reprint author), Univ New Mexico, Ctr Microelect Res, NASA, Inst Adv Microelect, 801 Univ Blvd SE,Suite 206, Albuquerque, NM 87106 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5492-3 PY 1999 BP 118 EP 121 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BQ78X UT WOS:000089525800029 ER PT B AU Drake, JT Prasad, NR AF Drake, JT Prasad, NR BE RamirezAngulo, J TI Current trend towards using soft computing approaches to phase synchronization in communication systems SO 42ND MIDWEST SYMPOSIUM ON CIRCUITS AND SYSTEMS, PROCEEDINGS, VOLS 1 AND 2 LA English DT Proceedings Paper CT 42nd Midwest Symposium on Circuits and Systems CY AUG 08-11, 1999 CL NEW MEXICO STATE UNIV, CORBETT CTR, LAS CRUCES, NM SP IEEE Circuits & Syst Soc, Klipsch Sch Elect & Comp Engn HO NEW MEXICO STATE UNIV, CORBETT CTR ID FUZZY AB This paper surveys recent advances in communications that utilize soft computing approaches to phase synchronization. Soft computing, as opposed to hard computing, is a collection of complementary methodologies that act in producing the most desirable control, decision, or estimation strategies. Recently, the communications area has explored the use of the principal constituents of soft computing, namely fuzzy logic, neural networks, and genetic algorithms, for modeling, control, and most recently for the estimation of phase in phase-coherent communications. If the receiver in a digital communications system is phase-coherent, as is often the case, phase synchronization is required. Synchronization thus requires estimation and/or control at the receiver of an unknown or random phase offset. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Drake, JT (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5492-3 PY 1999 BP 665 EP 668 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BQ78X UT WOS:000089525800159 ER PT B AU Djurdjevic, PD AF Djurdjevic, PD BE RamirezAngulo, J TI Real time adaptive fuzzy control of inverted pendulum SO 42ND MIDWEST SYMPOSIUM ON CIRCUITS AND SYSTEMS, PROCEEDINGS, VOLS 1 AND 2 LA English DT Proceedings Paper CT 42nd Midwest Symposium on Circuits and Systems CY AUG 08-11, 1999 CL NEW MEXICO STATE UNIV, CORBETT CTR, LAS CRUCES, NM SP IEEE Circuits & Syst Soc, Klipsch Sch Elect & Comp Engn HO NEW MEXICO STATE UNIV, CORBETT CTR ID NEURAL-NETWORK; ALGORITHM AB In this paper, we provide a real-time adaptive fuzzy controller utilized for balancing a self-erecting inverted pendulum with time-varying mechanical parameters. One learning algorithm is based upon truncated temporal back-propagation and weight perturbation suitable for realization in hardware. Main focus was the ability to learn from trials and the possibility to implement the functions in hardware for on-chip Learning. The simulations and testing were done using hardware-in-the-loop, the robustness and adaptivity of the controller are shown from simulation traces. C1 New Mexico Highlands Univ, Dept Engn, NASA, Ctr Autonomous Control Engn, Las Vegas, NV USA. RP Djurdjevic, PD (reprint author), New Mexico Highlands Univ, Dept Engn, NASA, Ctr Autonomous Control Engn, Las Vegas, NV USA. NR 19 TC 1 Z9 1 U1 1 U2 2 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5492-3 PY 1999 BP 910 EP 913 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BQ78X UT WOS:000089525800216 ER PT B AU Ghaffarian, R AF Ghaffarian, R GP IEEE IEEE TI Scale package implementation challenges SO 49TH ELECTRONIC COMPONENTS & TECHNOLOGY CONFERENCE - 1999 PROCEEDINGS LA English DT Proceedings Paper CT 49th Electronic Components and Technology Conference CY JUN 01-04, 1999 CL SAN DIEGO, CA SP Electr Components, Assemblies, Equipment & Supplies Assoc, IEEE Components, Packaging & Mfg Technol Soc, IEEE ID LEVEL RELIABILITY AB The JPL-led MicrotypeBGA Consortium of enterprises representing government agencies and private companies have jointed together to pool in-kind resources for developing the quality and reliability of chip scale packages (CSPs) for a variety of projects. In the process of building the Consortium CSP test vehicles, many challenges were identified regarding various aspects of technology implementation. This paper will present our experience in the areas of technology implementation challenges, including design and building both standard and microvia boards, and assembly of two types of test vehicles. We also discuss the most current package isothermal aging to 2,000 hours at 100 degrees C and 125 degrees C and thermal cycling test results to 1,700 cycles in the range of -30 to 100 degrees C. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Reza.Ghaffarian@JPL.NASA.Gov NR 5 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-5231-9 PY 1999 BP 619 EP 626 PG 8 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BN30H UT WOS:000081460000104 ER PT S AU Kucera, TA Antiochos, SK AF Kucera, TA Antiochos, SK BE Vial, JC KaldeichSchrumann, B TI Report of working group 5: Prominences and coronal mass ejections SO 8TH SOHO WORKSHOP: PLASMA DYNAMICS AND DIAGNOSTICS IN THE SOLAR TRANSITION REGION AND CORONA, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 8th SOHO Workshop on Plasma Dynamics and Diagnostics in the Solar Transition Region and Corona CY JUN 22-25, 1999 CL PARIS, FRANCE SP European Space Agcy, NASA, CNES, CNRS, INSU, Euroconf, Inst Astrophys Spatiale, Matra Marconi Space, SCOSTEP, Univ Paris XI ID SOLAR PROMINENCES; FLOWS AB Working Group 5 at the 8th SOHO Workshop covered a wide range of topics related to prominences and coronal mass ejections (CMEs). These included the properties of prominence plasmas particularly temperature densities and mass motions, and also prominence magnetic fields. CME topics included CME precursors, low-corona phenomena associated with CMEs and, again, magnetic structure and process involved in eruptions. Theories for prominence formation and CME initiation were also presented. C1 NASA, Goddard Space Flight Ctr, SM&A Corp, Greenbelt, MD 20771 USA. RP Kucera, TA (reprint author), NASA, Goddard Space Flight Ctr, SM&A Corp, Code 682, Greenbelt, MD 20771 USA. RI Kucera, Therese/C-9558-2012; Antiochos, Spiro/D-4668-2012 OI Antiochos, Spiro/0000-0003-0176-4312 NR 23 TC 1 Z9 1 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-784-4 J9 ESA SP PUBL PY 1999 VL 446 BP 97 EP 101 PG 5 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Physics, Fluids & Plasmas SC Astronomy & Astrophysics; Geochemistry & Geophysics; Physics GA BP62N UT WOS:000085712900012 ER PT S AU Ireland, J Walsh, RW Priest, ER Harrison, RA AF Ireland, J Walsh, RW Priest, ER Harrison, RA BE Vial, JC KaldeichSchrumann, B TI Wavelet analysis of active region oscillations SO 8TH SOHO WORKSHOP: PLASMA DYNAMICS AND DIAGNOSTICS IN THE SOLAR TRANSITION REGION AND CORONA, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 8th SOHO Workshop on Plasma Dynamics and Diagnostics in the Solar Transition Region and Corona CY JUN 22-25, 1999 CL PARIS, FRANCE SP European Space Agcy, NASA, CNES, CNRS, INSU, Euroconf, Inst Astrophys Spatiale, Matra Marconi Space, SCOSTEP, Univ Paris XI DE oscillations; chromosphere; transition region; corona; UV radiation ID SOLAR CORONAL LOOPS; RESONANT ABSORPTION; ALFVEN WAVES; POWER AB Time series arising from SOHO (Solar and Heliospheric Observatory) CDS-NIS (Coronal Diagnostic Spectrometer Normal Incidence Spectrometer) active region observations on 14th-15th November 1996 are used to demonstrate the applicability of wavelet methods. The localised nature of the wavelet transform allows us to study both the duration of any statistically significant oscillations as well as their period. The data consists of observations at approximately 14s cadence in He I 584.33 Angstrom (logT(e) = 4.3), O V 629.73 Angstrom (logT(e) = 5.3), Mg IX 368.06 Angstrom (log T-e = 6.0), Fe XVI 360.76 Angstrom (log T-e = 6.4). Such data provides detailed intensity information on the active region over a wide range of temperatures. The distribution of statistically significant periods found varies from line to line, as does their duration. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ireland, J (reprint author), NASA, Goddard Space Flight Ctr, Room G-1,Bldg 26,Mail Code 682-3, Greenbelt, MD 20771 USA. NR 27 TC 1 Z9 1 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-784-4 J9 ESA SP PUBL PY 1999 VL 446 BP 363 EP 368 PG 6 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Physics, Fluids & Plasmas SC Astronomy & Astrophysics; Geochemistry & Geophysics; Physics GA BP62N UT WOS:000085712900060 ER PT S AU MacNeice, PM Spicer, DS Antiochos, SK AF MacNeice, PM Spicer, DS Antiochos, SK BE Vial, JC KaldeichSchrumann, B TI A model for prominence mass and dynamics SO 8TH SOHO WORKSHOP: PLASMA DYNAMICS AND DIAGNOSTICS IN THE SOLAR TRANSITION REGION AND CORONA, PROCEEDINGS SE ESA Special Publications LA English DT Proceedings Paper CT 8th SOHO Workshop on Plasma Dynamics and Diagnostics in the Solar Transition Region and Corona CY JUN 22-25, 1999 CL PARIS, FRANCE SP European Space Agcy, NASA, CNES, CNRS, INSU, Euroconf, Inst Astrophys Spatiale, Matra Marconi Space, SCOSTEP, Univ Paris XI DE solar prominences ID SOLAR PROMINENCES AB We address two key issues concerning prominence/filament condensations: (1) the mechanism for their formation, and (2) the origin of their observed motions. Recent observations indicate that filament condensations move approximately horizontally with velocities of order 5 - 10 km/s. In this paper, we show that the condensations form due to a lack of thermal equilibrium in the magnetic flux tubes threading through the prominence corona. We use ARGOS a new 1D adaptive mesh, high-order Godunov code that includes both thermal conduction and radiation to simulate for the first time the complete formation process of a prominence condensation. We show that both the origin and the observed velocities are explained by our model. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, Mailstop 930-0, Greenbelt, MD 20771 USA. EM Spicer@gauss.gsfc.nasa.gov; Antiochos@nrl.navy.mil RI MacNeice, Peter/F-5587-2012; Antiochos, Spiro/D-4668-2012 OI Antiochos, Spiro/0000-0003-0176-4312 NR 16 TC 5 Z9 5 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-784-4 J9 ESA SPEC PUBL PY 1999 VL 446 BP 457 EP 459 PG 3 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Physics, Fluids & Plasmas SC Astronomy & Astrophysics; Geochemistry & Geophysics; Physics GA BP62N UT WOS:000085712900077 ER PT S AU Thompson, WT Brekke, P AF Thompson, WT Brekke, P BE Vial, JC KaldeichSchrumann, B TI EUV full Sun imaged spectral atlas using SOHO/CDS SO 8TH SOHO WORKSHOP: PLASMA DYNAMICS AND DIAGNOSTICS IN THE SOLAR TRANSITION REGION AND CORONA, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 8th SOHO Workshop on Plasma Dynamics and Diagnostics in the Solar Transition Region and Corona CY JUN 22-25, 1999 CL PARIS, FRANCE SP European Space Agcy, NASA, CNES, CNRS, INSU, Euroconf, Inst Astrophys Spatiale, Matra Marconi Space, SCOSTEP, Univ Paris XI DE EUV spectrocopy; irradiance; velocities; line widths AB The Coronal Diagnostic Spectrometer (CDS) aboard the Solar and Heliospheric Observatory (SOHO) carries out a regular program of measuring the full-disk irradiance using the Normal Incidence Spectrograph (NIS). The full-disk solar spectrum is returned in the wavelength bands 308-379 Angstrom and 513-633 Angstrom, with a spectral resolution between 0.3 and 0.6 Angstrom. A recent modification to the CDS on-board software allows simultaneous moderate resolution monochromatic images to be made of the stronger lines in these wavelength ranges. We report on observations made 23 April 1998, 21 May 1998, and 22 June 1998. A total of 69 monochromatic full-Sun images are extracted from the spectral line data. For the first time, spectrally resolved images of the full Sun in He II 303.8 Angstrom and Si XI 303.3 Angstrom are presented and compared. Velocity maps of the Sun in neutral and singly ionized helium are presented. Correlations of intensity to velocity over a wide range of transition region and coronal temperatures are shown. Lines from He I to Fe XIV show statistical redshifts of 1-3 km/s compared to active regions. Velocity maps of Mg IX and,X are presented, showing strong upflow and downflow regions associated with active regions, but not correlated with the brightest emission. Changes in line width are also presented in He II and Mg IX. C1 NASA, Goddard Space Flight Ctr, SM&A Corp, Greenbelt, MD 20771 USA. RP Thompson, WT (reprint author), NASA, Goddard Space Flight Ctr, SM&A Corp, Code 682-3, Greenbelt, MD 20771 USA. RI Thompson, William/D-7376-2012 NR 0 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-784-4 J9 ESA SP PUBL PY 1999 VL 446 BP 657 EP 662 PG 6 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Physics, Fluids & Plasmas SC Astronomy & Astrophysics; Geochemistry & Geophysics; Physics GA BP62N UT WOS:000085712900114 ER PT S AU Jordan, S Andretta, V Garcia, A Brosius, J Behring, W AF Jordan, S Andretta, V Garcia, A Brosius, J Behring, W BE Wilson, A TI Does velocity redistribution really enhance the He 304 angstrom line to observed intensities? SO 9TH EUROPEAN MEETING ON SOLAR PHYSICS: MAGNETIC FIELDS AND SOLAR PROCESSES, VOLS 1 AND 2 SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 9th European Meeting on Solar Physics CY SEP 12-18, 1999 CL UNIV FLORENCE, FLORENCE, ITALY SP European Union, European Space Agcy, Div joint Astrophys, Solar Phys Sect, Univ Firenze, Osservatorio Astrofis Arcetri, Agenzia Spaziale Italiana, CNR, Banca Commerciale Italiana, Banca Toscana, EPS HO UNIV FLORENCE DE transition region; He resonance line formation ID SOLAR TRANSITION REGION AB Previous work by this group has demonstrated that small-scale nonthermal velocities probably play a significant role in enhancing the intensity of the He II 304 Angstrom line above values predicted by the static atmopsphere NLTE theories, and more in conformity with Skylab and SOHO observations. This presentation briefly summarizes the evidence for this conclusion, emphasizing SOHO and correlated groundbased observations, of which examples are presented. However, in contrast to the previous studies, the tact taken here is more critical, asking the question "Can velocity redistribution fully explain the observations of the 304 Angstrom line, and what counter-indications and problems remain?" The conclusion reached is that, while velocity redistribution plays a significant role in the intensity enhancement, it may not be the whole story. Some other mechanism, associated with velocity filtration, may be at work. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Jordan, S (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-792-5 J9 ESA SP PUBL PY 1999 VL 448 BP 303 EP 306 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BP86P UT WOS:000086446800049 ER PT S AU Suess, ST Nerney, S AF Suess, ST Nerney, S BE Wilson, A TI MHD streamer structure, slow solar wind, and the streamer brightness boundary SO 9TH EUROPEAN MEETING ON SOLAR PHYSICS: MAGNETIC FIELDS AND SOLAR PROCESSES, VOLS 1 AND 2 SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 9th European Meeting on Solar Physics CY SEP 12-18, 1999 CL UNIV FLORENCE, FLORENCE, ITALY SP European Union, European Space Agcy, Div joint Astrophys, Solar Phys Sect, Univ Firenze, Osservatorio Astrofis Arcetri, Agenzia Spaziale Italiana, CNR, Banca Commerciale Italiana, Banca Toscana, EPS HO UNIV FLORENCE DE streamers; theory; MHD; solar wind AB Flow tubes adjacent to closed magnetic field lines on the boundaries of streamers can have spreading factors which change rapidly with height. Numerical models in this thin layer are subject to uncertainties. Here we use an analytic model of magnetically closed and adjacent open regions to analyze the spreading factor close to the closed field lines. The model is based on the one-temperature, isothermal flow model of Pneuman (1968), extended to calculate spreading factors and plasma beta, and to better explain streamer evolution with increasing temperature. C1 NASA, Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Suess, ST (reprint author), NASA, Marshall Space Flight Ctr, SD50, Huntsville, AL 35812 USA. NR 16 TC 1 Z9 1 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-792-5 J9 ESA SP PUBL PY 1999 VL 448 BP 1101 EP 1106 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BP86P UT WOS:000086446800178 ER PT B AU Allman, M Paxson, V AF Allman, M Paxson, V BE Guerin, R TI On estimating end-to-end network path properties SO ACM SIGCOMM'99 CONFERENCE: APPLICATIONS, TECHNOLOGIES, ARCHITECTURES, AND PROTOCOLS FOR COMPUTER COMMUNICATIONS SE COMPUTER COMMUNICATIONS REVIEW LA English DT Proceedings Paper CT ACM Conference on Applications, Technologies, Architectures, and Protocols for Computer Communications (SIGCOMM 99) CY AUG 30-SEP 03, 1999 CL HARVARD UNIV, CAMBRIDGE, MA SP Assoc Computing Machinery, Abrizio, Growth Networks, GTE, MCI Worldcom, Microsoft Res, Nortel, Wiley Networking Council HO HARVARD UNIV AB The more information about current network conditions available to a transport protocol, the more efficiently it can use the network to transfer its data. In networks such as the Internet, the transport protocol must often form. its own estimates of network properties based on measurements performed by the connection endpoints. We consider two basic transport estimation problems: determining the setting of the retransmission timer (RTO) for a reliable protocol, and estimating the bandwidth available to a connection as it begins. We look at both of these problems in the context of TCP, using a large TCP measurement set [Pax97b] for trace-driven simulations. For RTO estimation, we evaluate a number of different algorithms, finding that the performance of the estimators is dominated by their minimum values, and to a lesser extent, the timer granularity, while being virtually unaffected by how often round-trip time measurements are made or the settings of the parameters in the exponentially-weighted moving average estimators commonly used. For bandwidth estimation, we explore techniques previously sketched in the literature [Hoe96, AD98] and find that in practice they perform less well than anticipated. We then develop a receiver-side algorithm that performs significantly better. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Allman, M (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS 54-2, Cleveland, OH 44135 USA. NR 33 TC 24 Z9 25 U1 0 U2 2 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036-9998 USA BN 1-58113-135-6 J9 COMP COMM R PY 1999 VL 29 IS 4 BP 263 EP 274 PG 12 WC Computer Science, Software Engineering; Telecommunications SC Computer Science; Telecommunications GA BN91H UT WOS:000083442200021 ER PT S AU Lurie, BJ Hench, JJ Ahmed, A Hadaegh, FY AF Lurie, BJ Hench, JJ Ahmed, A Hadaegh, FY BE Masten, MK Stockum, LA TI Nonlinear control of the optical delay line pathlength SO ACQUISITION, TRACKING, AND POINTING XIII SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Acquisition, Tracking, and Pointing XIII Conference CY APR 07-08, 1999 CL ORLANDO, FL SP SPIE DE nonlinear control; main-vernier control; optical delay line; interferometer AB This paper discusses the problem of designing a control system for an interferometer delay line which contains coarse-vernier loops. The vernier loop compensator has nonlinear dynamics and includes a local feedback path containing a deadzone. This accomplishes two objectives: global stability and good transient response to large signals. In addition, by ensuring global stability in the vernier loop, the gain of the coarse loop may be increased thus providing greater disturbance rejection in the overall loop. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lurie, BJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 4 Z9 4 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3166-4 J9 P SOC PHOTO-OPT INS PY 1999 VL 3692 BP 139 EP 149 DI 10.1117/12.352856 PG 11 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA BN65T UT WOS:000082494300015 ER PT J AU Henry, PK Terrile, RJ Maddock, RW Sobel, HR AF Henry, PK Terrile, RJ Maddock, RW Sobel, HR TI Exploring the Kuiper Belt: An extended Pluto mission SO ACTA ASTRONAUTICA LA English DT Article AB A robotic flyby mission to the planet Pluto is being planned for launch early in the next decade. The spacecraft will continue on out of the solar system in an almost radial direction traveling at about four AU per year and begin transiting the Kuiper Belt shortly after Pluto encounter. Recent discoveries and observations of Kuiper Belt objects have generated increased interest in the characteristics of these bodies. This paper examines the opportunities and requirements for extending the Pluto mission to include the search for, and encounters with, objects in the Kuiper Disk at 40+ AU. The trajectory and Delta V requirements will be presented. An automated, on-board sky survey will be proposed to inventory the Kuiper objects in the vicinity of the flight path and to identify which objects are candidates for altering the trajectory for a close flyby. A possible Kuiper object encounter science scenario will be described. (C) 1999 Published by Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Outer Planets Solar Probe Project, Pasadena, CA 91109 USA. RP Henry, PK (reprint author), CALTECH, Jet Prop Lab, Outer Planets Solar Probe Project, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Frank, David/E-8213-2012 NR 10 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JAN-FEB PY 1999 VL 44 IS 2-4 BP 85 EP 90 DI 10.1016/S0094-5765(99)00032-6 PG 6 WC Engineering, Aerospace SC Engineering GA 201AQ UT WOS:000080572800003 ER PT J AU Anderson, JL AF Anderson, JL TI Roadmap to a star SO ACTA ASTRONAUTICA LA English DT Article ID ASTEROIDS; COMETS AB NASA is currently constructing an Interstellar Roadmap that will outline a progressive series of phased technology efforts over several decades that would enable new science beyond the solar system,leading to and culminating in robotics exploration of nearby stars. The Roadmap is structured around a decadal progression of science missions and enabling technologies in which each decadal cycle has an intrinsic value in itself. The Roadmap serves at least 5 functions: 1) it lays the foundation for the development of a broad new strategic thrust of space exploration and development; 2) it outlines a long term progressive program for which each phase has an intrinsic value and can be argued independently of a Star Mission itself; 3) it defines a phased approach that would culminate in a large scale breakthrough beamed energy capability that would have broad planetary and terrestrial applicability; 4) it describes an endeavor that could provide the technological basis of a U.S. economic engine for the first half of the 21st century; and 5) it provides a focus and a structure around which new government/industry economic relationships may be established. This paper outlines the process for constructing the Roadmap which is due to be completed in Fall 1998. It also poses questions raised by a mission of such scale and suggests some of the strategic value of such a Roadmap. (C) 1999 Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Off Space Sci, Washington, DC 20546 USA. RP Anderson, JL (reprint author), NASA, Off Space Sci, Washington, DC 20546 USA. NR 16 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JAN-FEB PY 1999 VL 44 IS 2-4 BP 91 EP 97 DI 10.1016/S0094-5765(99)00033-8 PG 7 WC Engineering, Aerospace SC Engineering GA 201AQ UT WOS:000080572800004 ER PT J AU West, JL AF West, JL TI Design issues for a mission to exploit the gravitational lensing effect at 550 AU SO ACTA ASTRONAUTICA LA English DT Article AB Reported herein are the first results of a NASA-sponsored study at the Jet Propulsion Laboratory (JPL), California Institute of Technology, exploring the scientific promise and technological viability of a mission to exploit the gravitational lensing effect of the Sun to obtain huge antenna gains for electromagnetic waves grazing the Sun's disk. With regard to scientific promise, these results, reported at about the halfway point of the study, substantiate the huge antenna gains offered by, as it will be called here, a Solar Gravitational Telescope (SGT) and point to the instrument's potential promise as a "discovery machine" but suggest considerable limitations to the telescope's usefulness as a general purpose astrophysical research tool. These limitations are seen to arise, primarily, from the geometry and scale of the "virtual" telescope which must be achieved and maintained to utilize the lensing effect and the turbulence effects of the Sun's plasma on the observed target's signal. With regard to technological viability, the preliminary results suggest a very aggressive use of unproven, as-yet-unflown new technology will be required to enable the desired science observations and mission durations approaching the short (3-10 year) NASA-targeted mission duration goal. Key needed new technologies are advanced propulsion, lightweight telescopes, membrane mirrors, inflatable/rigidizeable structures, and novel coronagraphic techniques. (C) 1999 Published by Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP West, JL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 6 Z9 6 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JAN-FEB PY 1999 VL 44 IS 2-4 BP 99 EP 107 DI 10.1016/S0094-5765(99)00034-X PG 9 WC Engineering, Aerospace SC Engineering GA 201AQ UT WOS:000080572800005 ER PT J AU Millis, MG AF Millis, MG TI NASA Breakthrough Propulsion Physics program SO ACTA ASTRONAUTICA LA English DT Article ID GENERAL-RELATIVITY; FORCE; VACUUM; TRAVEL; ENERGY; DRIVE AB In 1996, NASA established the Breakthrough Propulsion Physics program to seek the ultimate breakthroughs in space transportation: propulsion that requires no propellant mass, propulsion that attains the maximum transit speeds physically possible, and breakthrough methods of energy production to power such devices. Topics of interest include experiments and theories regarding the coupling of gravity and electromagnetism, vacuum fluctuation energy, warp drives and wormholes, and superluminal quantum effects. Because these propulsion goals are presumably far from fruition, a special emphasis is to identify affordable, near-term, and credible research that could make measurable progress toward these propulsion goals. The methods of the program and the results of the 1997 workshop are presented. This Breakthrough Propulsion Physics program, managed by Lewis Research Center, is one part of a comprehensive, long range Advanced Space Transportation Plan managed by Marshall Space Flight Center. (C) 1999 Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Lewis Res Ctr, Breakthrough Prop Phys Program, Cleveland, OH 44135 USA. RP Millis, MG (reprint author), NASA, Lewis Res Ctr, Breakthrough Prop Phys Program, 21000 Brookpk Rd ,MS 60-4, Cleveland, OH 44135 USA. NR 67 TC 15 Z9 16 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JAN-FEB PY 1999 VL 44 IS 2-4 BP 175 EP 182 DI 10.1016/S0094-5765(99)00045-4 PG 8 WC Engineering, Aerospace SC Engineering GA 201AQ UT WOS:000080572800016 ER PT J AU Woerner, DF AF Woerner, DF TI Revolutionary systems and technologies for missions to the outer planets SO ACTA ASTRONAUTICA LA English DT Article AB The Advanced Deep Space System Development Program is managed by the Jet Propulsion Laboratory for NASA and is also called X2000. X2000 is organized to create advanced flight and ground systems for the exploration of the outer planets and beyond; it has been created to develop the engineering elements of flight and ground systems. Payloads will be developed by another team. Each X2000 delivery gets its requirements from a set of planned missions, or "mission customers". The X2000 First Delivery Project supports missions to the Sun (to 4 solar radii), Europa (looking for a liquid ocean), Mars (in support of several Mars missions including a sample return), a comet (including a sample return), and Pluto followed by a trip info the Kuiper belt. This set of missions leads to some outstanding requirements: 1. Long-life (10-12 years) 2. Total Ionizing Dose of 4 Mrad (for a Europa Orbiter) 3. Average power consumption less than or equal to 150 Watts 4. Autonomous operations that result in an extreme reduction in operations costs This paper describes the X2000 first delivery and its technologies following a brief overview of the program. (C) 1999 Published by Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Woerner, DF (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 179-2200, Pasadena, CA 91109 USA. NR 2 TC 1 Z9 1 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JAN-FEB PY 1999 VL 44 IS 2-4 BP 187 EP 192 DI 10.1016/S0094-5765(99)00047-8 PG 6 WC Engineering, Aerospace SC Engineering GA 201AQ UT WOS:000080572800018 ER PT J AU Quadrelli, MB Atluri, SN AF Quadrelli, MB Atluri, SN TI Mixed variational principles in space and time for elastodynamics analysis SO ACTA MECHANICA LA English DT Article ID SPATIAL BEAMS AB Nonlinear elastodynamics problems are approached from the point of view of a mixed variational principle. Tt is shown that four different functionals lead to different formulations of the problem with different independent fields. One of the functionals is specialized to the case of spatial beams undergoing large deformations, and small strains. The extension of these functionals to the case in which kinematic constraints are presented leads to the useful concept of dual constraints, which can be advantageously employed in treating problems involving contact, impact, and changing topology. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Ctr Aerosp Res & Educ, Los Angeles, CA 90095 USA. RP Quadrelli, MB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Atluri, Satya/C-5040-2013 OI Atluri, Satya/0000-0001-6793-9619 NR 17 TC 3 Z9 3 U1 0 U2 4 PU SPRINGER-VERLAG WIEN PI VIENNA PA SACHSENPLATZ 4-6, PO BOX 89, A-1201 VIENNA, AUSTRIA SN 0001-5970 J9 ACTA MECH JI Acta Mech. PY 1999 VL 136 IS 3-4 BP 193 EP 208 DI 10.1007/BF01179257 PG 16 WC Mechanics SC Mechanics GA 221AF UT WOS:000081701500006 ER PT S AU Stone, NH Raitt, WJ Wright, KH AF Stone, NH Raitt, WJ Wright, KH BE James, HG Raitt, WJ Sultzer, MP TI The TSS-1R electrodynamic tether experiment: Scientific and technological results SO ACTIVE EXPERIMENTS IN SPACE PLASMAS SE ADVANCES IN SPACE RESEARCH LA English DT Article; Proceedings Paper CT D0 8 Symposium of COSPAR Scientific Commission D Held at the 32nd COSPAR Scientific Assembly CY JUL 12-19, 1998 CL NAGOYA, JAPAN SP Int Union Radio Sci, Comm Space Res ID CURRENT COLLECTION; SATELLITE; MISSION; WAVES; 1R AB The Tethered Satellite System program was designed to provide the opportunity to explore certain space plasma-electrodynamic processes (associated with high-voltage bodies and electrical currents in space) and the orbital mechanics of a gravity-gradient stabilized system of two satellites linked by a long conducting tether. A unique data set was obtained during the TSS-1R mission in which the tether electromotive force and current reached values in excess of 3500 volts and 1 amp, respectively. The insight this has allowed into the current collection process and the physics of high-voltage plasma sheaths is significant. Previous theoretical models of current collection were electrostatic-assuming that the orbital motion of the system, which is highly subsonic with respect to electron thermal motion, was unimportant. This may still be acceptable for the case of relatively slow-moving sounding rockets. However, the TSS-1R results show that motion relative to the plasma does affect current collection and must be accounted for in orbiting systems. (C) 1999 COSPAR. Published by Elsevier Science Ltd. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Utah State Univ, Ctr Atmospher & Space Sci, Logan, UT 84322 USA. Univ Alabama, Ctr Space Plasma & Aeron Res, Huntsville, AL 35899 USA. RP Stone, NH (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. NR 25 TC 14 Z9 16 U1 0 U2 5 PU PERGAMON PRESS LTD PI OXFORD PA THE BOULEVARD LANGFORD LANE KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0273-1177 J9 ADV SPACE RES PY 1999 VL 24 IS 8 BP 1037 EP 1045 DI 10.1016/S0273-1177(99)00551-7 PG 9 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BP17V UT WOS:000084336900012 ER PT S AU Johnson, L Gilchrist, B Estes, RD Lorenzini, E AF Johnson, L Gilchrist, B Estes, RD Lorenzini, E BE James, HG Raitt, WJ Sultzer, MP TI Overview of future NASA tether applications SO ACTIVE EXPERIMENTS IN SPACE PLASMAS SE ADVANCES IN SPACE RESEARCH LA English DT Article; Proceedings Paper CT D0 8 Symposium of COSPAR Scientific Commission D Held at the 32nd COSPAR Scientific Assembly CY JUL 12-19, 1998 CL NAGOYA, JAPAN SP Int Union Radio Sci, Comm Space Res AB The groundwork has been laid for tether applications in space. NASA has developed tether technology for space applications since the 1960's. Important recent milestones include retrieval of a tether in space (TSS-1, 1992), successful deployment of a 20-km-long tether in space (SEDS-1, 1993), closed loop control of tether deployment (SEDS-2, 1994), and operation of an electrodynamic tether with tether current driven in both directions-power and thrust modes (PMG, 1993). Various types of tethers and systems can be used for space transportation. Short electrodynamic tethers can use solar power to "push" against a planetary magnetic field to achieve propulsion without the expenditure of propellant. The planned Propulsive Small Expendable Deployer System (ProSEDS) experiment will demonstrate electrodynamic tether thrust during its flight in early 2000. Utilizing completely different physical principles, long nonconducting tethers can exchange momentum between two masses in orbit to place one body into a higher orbit or a transfer orbit for lunar and planetary missions. Recently completed system studies of this concept indicate that it would be a relatively low-cost, in-space asset with long-term, multimission capability. Tethers can also be used to support space science by providing a mechanism for precision formation flying and for reaching regions of the upper atmosphere that were previously inaccessible. (C) 1999 COSPAR. Published by Elsevier Science Ltd. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Michigan, Space Phys Res Lab, Ann Arbor, MI 48109 USA. Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. RP Johnson, L (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 10 TC 17 Z9 23 U1 0 U2 8 PU PERGAMON PRESS LTD PI OXFORD PA THE BOULEVARD LANGFORD LANE KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0273-1177 J9 ADV SPACE RES PY 1999 VL 24 IS 8 BP 1055 EP 1063 DI 10.1016/S0273-1177(99)00553-0 PG 9 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BP17V UT WOS:000084336900014 ER PT S AU Smith, HE Lonsdale, CJ Lonsdale, CJ Diamond, PJ AF Smith, HE Lonsdale, CJ Lonsdale, CJ Diamond, PJ BE Terzian, Y Weedman, D Khachikian, E TI VLBI Imaging of Luminous Infrared Galaxies: Starbursts & AGN SO ACTIVE GALACTIC NUCLEI AND RELATED PHENOMENA SE IAU SYMPOSIA LA English DT Article; Proceedings Paper CT 194th Symposium of the International-Astronomical-Union CY AUG 17-22, 1998 CL BYURAKAN, ARMENIA SP Int Astron Union ID MARKARIAN 231; ARP-220; CONNECTION; QUASARS AB Luminous Infrared Galaxies (LIGs) are locally more numerous than normal galaxies, AGN, and QSOs above L similar to 10(11)L. and may be the evolutionary precursors of classical radio-quiet quasars. VLBI observations of a complete sample show that high-T-b radio cores are common, perhaps universal among LIGs. VLBI imaging shows that these radio cores may be produced by intense starbursts which generate luminous radio supernovae, as in the case of Arp 220 (Smith et al. 1998), or by a classical AGN core, as in the case of Mrk 231, which we interpret as a newly formed QSO emerging from a starburst. Compact OH 1667MHz maser emission appears to be common in LIGs and may be related to AGN activity. These results lend further support to the scenario suggested by Sanders et al (1988) in which mergers of gas-rich galaxies lead first to luminous starbursts which evolve into radio-quiet quasars. C1 Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Univ Calif San Diego, Dept Phys, La Jolla, CA 92093 USA. CALTECH, Ctr Infrared Proc & Anal, JPL, Pasadena, CA 91125 USA. MIT, Haystack Observ, Westford, MA 01886 USA. Natl Radio Astron Observ, Socorro, NM 87801 USA. RP Smith, HE (reprint author), Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. NR 23 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0074-1809 BN 1-58381-008-0 J9 IAU SYMP PY 1999 IS 194 BP 60 EP 65 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34N UT WOS:000175726500007 ER PT S AU Kaiser, ME Bradley, LD Hutchings, JB Kraemer, SB Crenshaw, DM Ruiz, J Weistrop, D Nelson, C Gull, TR AF Kaiser, ME Bradley, LD Hutchings, JB Kraemer, SB Crenshaw, DM Ruiz, J Weistrop, D Nelson, C Gull, TR BE Terzian, Y Weedman, D Khachikian, E TI Kinematic mapping of the narrow line region of NGC4151 SO ACTIVE GALACTIC NUCLEI AND RELATED PHENOMENA SE IAU SYMPOSIA LA English DT Article; Proceedings Paper CT 194th Symposium of the International-Astronomical-Union CY AUG 17-22, 1998 CL BYURAKAN, ARMENIA SP Int Astron Union ID RADIO AB We present HSTSpace Telescope Imaging Spectrograph (STIS) slitless Spectroscopy of the NGC4151 narrow line region (NLR) as a probe of the kinematic stucture of the extended emission-line gas emanating from the nucleus. Using slitless spectroscopy at two roll angles (with a spatial resolution of 0.051 "/pixel and a point source spectral resolution of 0.55 Angstrom) augmented with narrow band images, we have mapped the velocity field of the NLR as defined by similar to60 discrete cloud structures in [OIII]. Flux measurements of [OII], Hbeta, [OIII], [OI], and [SII] were made for individual cloud structures wherever possible. The emission line clouds have a biconical distribution which extends further SW than NE of the nucleus (Figure 1). In general, the SW clouds have approaching velocities, whereas the NE clouds are receding. Higher velocity clouds, as well as higher velocity dispersion clouds, are located within approximately +/- 180 pc of the nucleus. The bicone axis is roughly coincident with the radio axis (Pedlar et al., 1993, Winge et al., 1997). C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Natl Res Council Canada, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Kaiser, ME (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 6 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0074-1809 BN 1-58381-008-0 J9 IAU SYMP PY 1999 IS 194 BP 79 EP 81 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34N UT WOS:000175726500012 ER PT S AU Tsou, H Racho, C Yan, TY AF Tsou, H Racho, C Yan, TY BE Tyson, RK Fugate, RQ TI The extended-image spatial tracking technique for deep-space optical downlinks SO ADAPTIVE OPTICS SYSTEMS AND TECHNOLOGY SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Adaptive Optics Systems and Technology CY JUL 21-22, 1999 CL DENVER, CO SP SPIE DE optical pointing; extended-image tracking; image stabilization; maximum likelihood estimation; optical communications AB This paper describes an extended-image tracking technique based on the maximum likelihood estimation. The target image is assume to have a known profile covering more than one element of a focal plane detector array. It is assumed that the relative position between the imager and the target is changing with time and the received target image has each of its pixels disturbed by an independent additive white Gaussian noise. When a rotation-invariant movement between imager and target is considered, the maximum likelihood based image tracking technique described in this paper is a closed-loop structure capable of providing iterative update of the movement estimate by calculating the loop feedback signals from a weighted correlation between the currently received target image and the previously estimated reference image in the transform domain. The movement estimate is then used to direct the imager to closely follow the moving target. This image tracking technique has many potential applications, including free-space optical communications and astronomy where accurate and stabilized optical pointing is essential. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tsou, H (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3248-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3762 BP 101 EP 109 DI 10.1117/12.363565 PG 9 WC Optics SC Optics GA BN95E UT WOS:000083637400011 ER PT J AU DallBauman, LA Finn, JE AF DallBauman, LA Finn, JE TI Adsorption processes in spacecraft environmental control and life support systems SO ADSORPTION AND ITS APPLICATIONS IN INDUSTRY AND ENVIRONMENTAL PROTECTION, VOL II: APPLICATIONS IN ENVIRONMENTAL PROTECTION SE STUDIES IN SURFACE SCIENCE AND CATALYSIS LA English DT Article AB The environmental control and life support system on a spacecraft maintains a safe and comfortable environment in which the crew can live and work by supplying oxygen and water and by removing carbon dioxide, water vapor, and trace contaminants from cabin air. Although open-loop systems have been used successfully in the past for short-duration missions, the economics of current and future long-duration missions in space will make nearly complete recycling of air and water imperative. A variety of operations will be necessary to achieve the goal of nearly complete recycling. These include separation and reduction of carbon dioxide, removal of trace gas-phase contaminants, recovery and purification of humidity condensate, purification and polishing of wastewater streams, and others. Several of these can be performed totally or in part by adsorption processes. These processes are good candidates to perforin separations and purifications in space due to their gravity independence, high reliability, relatively high energy efficiency, design flexibility, technological maturity, and regenerative nature. For these reasons, adsorption has historically played a key role in life support on U.S. and Russian piloted spacecraft. Among the life support applications that can be achieved through use of adsorption technology are removal of trace contaminants and carbon dioxide from cabin air and recovery of potable water from waste streams. In each of these cases, adsorption technology has been selected for use onboard the International Space Station. The requirements, science, and hardware for these applications are discussed. Human space exploration may eventually lead to construction of planetary habitats. These habitats may provide additional opportunities for use of adsorption processes, such as control of greenhouse gas composition, and may have different resources available to them, such as gases present in the planetary atmosphere. Separation and purification processes based on adsorption can be expected to continue to fulfill environmental control and life support needs on future missions. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP DallBauman, LA (reprint author), Allied Signal Inc, 50 E Algonquin Rd, Des Plaines, IL 60017 USA. NR 36 TC 9 Z9 10 U1 3 U2 17 PU ELSEVIER SCIENCE PUBL B V PI AMSTERDAM PA SARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2991 J9 STUD SURF SCI CATAL PY 1999 VL 120 BP 455 EP 471 PN B PG 17 WC Chemistry, Physical SC Chemistry GA BM94L UT WOS:000080198600015 PM 12741388 ER PT J AU Smialek, JL Robinson, RC Opila, EJ Fox, DS Jacobson, NS AF Smialek, JL Robinson, RC Opila, EJ Fox, DS Jacobson, NS TI SiC and Si3N4 recession due to SiO2 scale volatility under combustor conditions SO ADVANCED COMPOSITE MATERIALS LA English DT Article DE SiC; Si3N4; oxidation; scale volatility; combustor; water vapor ID WATER-VAPOR AB SiC and Si3N4 materials were tested under various turbine engine combustion environments, chosen to represent either conventional fuel-lean or fuel-rich mixtures proposed for high speed aircraft. Representative CVD, sintered, and composite materials were evaluated in both furnace and high pressure burner rig exposure. While protective SiO2 scales form in all cases, evidence is pre sented to support paralinear growth kinetics, i.e. parabolic growth moderated simultaneously by linear volatilization. The volatility rate is dependent on temperature, moisture content, system pressure, and gas velocity. The burner tests were used to map SiO2 volatility (and SiC recession) over a range of temperature, pressure, and velocity. The functional dependency of material recession (volatility) that emerged followed the form: exp(-Q/RT) * P-x * v(y). These empirical relations were compared to rates predicted from the thermodynamics of volatile SiO and SIOxHy reaction products and a kinetic model of diffusion through a moving boundary layer. For typical combustion conditions, recession of 0.2 to 2 mu m/h is predicted at 1200-1400 degrees C, far in excess of acceptable long term limits. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Smialek, JL (reprint author), NASA, Lewis Res Ctr, 21000 Brookpark Rd, Cleveland, OH 44135 USA. NR 10 TC 94 Z9 98 U1 4 U2 18 PU VSP BV PI ZEIST PA PO BOX 346, 3700 AH ZEIST, NETHERLANDS SN 0924-3046 J9 ADV COMPOS MATER JI Adv. Compos. Mater. PY 1999 VL 8 IS 1 BP 33 EP 45 DI 10.1163/156855199X00056 PG 13 WC Materials Science, Composites SC Materials Science GA 177PM UT WOS:000079219400005 ER PT B AU Yamada, T AF Yamada, T BE Cahay, M Bandyopadhyay, S Lockwood, DJ Koshida, N Leburton, JP Meyyappan, M Sakamoto, T TI Precise nanoelectronics with adatom chains SO ADVANCED LUMINESCENT MATERIALS AND QUANTUM CONFINEMENT SE ELECTROCHEMICAL SOCIETY SERIES LA English DT Proceedings Paper CT International Symposium on Advanced Luminescent Materials and Quantum Confinement, at the 196th Meeting of the Electrochemical-Society CY OCT 18-20, 1999 CL HONOLULU, HI SP Electrochem Soc Inc, Natl Sci Fdn, USA Res Off ID SCANNING TUNNELING MICROSCOPE; SURFACES; SCALE; STM AB Adatom chains on an atomically regulated substrate will be building components in future precise nanoelectronics. Adatoms need to be secured with chemical bonding, but then electronic isolation between the adatom and substrate systems is not guaranteed. A one-dimensional model shows that good isolation with existence of surface states is expected on an s-p crossing substrate such as Si, Ge, or GaAs, reflecting the bulk nature of the substrate. Isolation is better if adatoms are electronically similar to the substrate atoms, and can be manipulated by hydrogenation. Chain structures with group IV adatoms with two chemical bonds, or group III adatoms with one chemical bond, are semiconducting, reflecting the surface nature of the substrate. These structures are unintentionally doped due to the charge transfer across the chemical bonds. Physical properties of adatom chains have to be determined for the unified adatom-substrate system. C1 NASA, Ames Res Ctr, MRJ, Moffett Field, CA 94035 USA. RP Yamada, T (reprint author), NASA, Ames Res Ctr, MRJ, M-S T27A-1, Moffett Field, CA 94035 USA. NR 28 TC 0 Z9 0 U1 0 U2 0 PU ELECTROCHEMICAL SOCIETY INC PI PENNINGTON PA 65 S MAIN ST, PENNINGTON, NJ 08534-2839 USA BN 1-56677-245-1 J9 ELEC SOC S PY 1999 VL 99 IS 22 BP 283 EP 293 PG 11 WC Electrochemistry; Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Optics; Physics, Applied SC Electrochemistry; Engineering; Materials Science; Optics; Physics GA BN84W UT WOS:000083176000028 ER PT S AU Mackey, JR Das, KK AF Mackey, JR Das, KK BE Fallahi, M Swanson, BI TI Wavelet-based denoising and ratiometric recombination of polarization-modulated stress-induced birefringence measurement signals SO ADVANCED MATERIALS AND OPTICAL SYSTEMS FOR CHEMICAL AND BIOLOGICAL DETECTION SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Advanced Materials and Optical Systems for Chemical and Biological Detection CY SEP 21-22, 1999 CL BOSTON, MA SP SPIE, Los Almos Natl Lab, Air & Waste Management Assoc, Div Opt Sci DE birefringence; retardation; electro-optic modulator; wavelets; denoising ID MUELLER MATRIX; LIGHT AB We have developed an instrument that measures fast transient birefringence and polymer chain orientation angle in complex fluids. This instrument uses a dual-crystal transverse Electro-Optic (EO) modulator with second crystal's modulation voltage applied 180 degrees out of phase from that of the first crystal. The precise measurement of birefringence using this instrument strictly depends on three separate signals. These are the de, first and second harmonic voltages. The harmonics are relatively noise-free while the de signal is subject to appreciable noise. Therefore, wavelet based noise reduction techniques have been used to denoise the measured de signal. The de-noised signal was recombined with the harmonic signals to obtain retardation and birefringence measurements using a high precision 1/16 wave plate in a rotating mount to simulate a birefringence sample. C1 NASA, Analex Corp, Glenn Corp, Cleveland, OH 44142 USA. RP Mackey, JR (reprint author), NASA, Analex Corp, Glenn Corp, 3001 Aerosp Pkwy, Cleveland, OH 44142 USA. NR 14 TC 1 Z9 1 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3451-5 J9 P SOC PHOTO-OPT INS PY 1999 VL 3858 BP 240 EP 248 DI 10.1117/12.372923 PG 9 WC Environmental Sciences; Instruments & Instrumentation; Multidisciplinary Sciences; Optics SC Environmental Sciences & Ecology; Instruments & Instrumentation; Science & Technology - Other Topics; Optics GA BP39Q UT WOS:000084986400029 ER PT S AU Belvin, HL Cano, RJ Treasure, M Shahood, TW AF Belvin, HL Cano, RJ Treasure, M Shahood, TW BE Green, J Howell, DD TI Fabrication of carbon-boron reinforced dry polymer matrix composite tape SO ADVANCED MATERIALS & PROCESSES PREPARING FOR THE NEW MILLENNIUM SE INTERNATIONAL SAMPE TECHNICAL CONFERENCE SERIES LA English DT Proceedings Paper CT 31st International SAMPE Technical Conference on Advanced Materials and Processes Preparing for the New Millennium CY OCT 26-30, 1999 CL CHICAGO, IL DE boron; composite; reinforcement ID PREPREG AB Future generation aerospace vehicles will require specialized hybrid material forms for component structure fabrication. For this reason, high temperature composite prepregs in both dry and wet forms are being developed at NASA Langley Research Center (LaRC). In an attempt to improve compressive properties of carbon fiber reinforced composites, a hybrid carbon-boron tape was developed and used to fabricate composite laminates which were subsequently cut into flexural and compression specimens and tested. The hybrid material, given the designation HYCARB, was fabricated by modifying a previously developed process for the manufacture of dry polymer matrix composite (PMC) tape at LaRC. In this work, boron fibers were processed with IM7/ LaRCTM IAX poly(amide acid) solution-coated prepreg to form a dry hybrid tape for Automated Tow Placement (ATP). Boron fibers were encapsulated between two (2) layers of reduced volatile, low fiber areal weight poly(amide acid) solution-coated prepreg. The hybrid prepreg was then fully imidizied and consolidated into a dry tape suitable for ATP. The fabrication of a hybrid boron material form for tow placement aids in the reduction of the overall manufacturing cost of boron reinforced composites, while realizing the improved compression strengths. Composite specimens were press-molded from the hybrid material and exhibited excellent mechanical properties. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Belvin, HL (reprint author), NASA, Langley Res Ctr, 6A W Taylor St, Hampton, VA 23681 USA. NR 6 TC 0 Z9 0 U1 0 U2 1 PU SOC ADVANCEMENT MATERIAL & PROCESS ENGINEERING PI COVINA PA 1161 PARKVIEW DR,, COVINA, CA 91724-3748 USA SN 0892-2624 BN 0-938994-85-9 J9 INT SAMPE TECH CONF PY 1999 VL 31 BP 329 EP 340 PG 12 WC Materials Science, Multidisciplinary; Materials Science, Composites SC Materials Science GA BP22M UT WOS:000084441300031 ER PT S AU Chamis, CC AF Chamis, CC BE Green, J Howell, DD TI Computational simulation methods to evaluate design concepts from advanced materials SO ADVANCED MATERIALS & PROCESSES PREPARING FOR THE NEW MILLENNIUM SE INTERNATIONAL SAMPE TECHNICAL CONFERENCE SERIES LA English DT Proceedings Paper CT 31st International SAMPE Technical Conference on Advanced Materials and Processes Preparing for the New Millennium CY OCT 26-30, 1999 CL CHICAGO, IL DE multi-discipline; coupling effects; composites; thermal; structural; acoustic; processing; tailoring AB Effective computational simulation methods are described for modeling the inherent multi-disciplinary interactions which arise from introducing new materials and which govern the accurate response of propulsion systems. Results are presented for propulsion system responses including multi-disciplinary coupling effects using (1) coupled multi-discipline thermal/structural/acoustic tailoring, (2) an integrated system of multi-disciplinary simulators, (3) coupled material-behavior/fabrication process tailoring, (4) sensitivities using a probabilistic simulator, (5) multi-advanced material, and (6) coupled materials/structures/fracture/probabilistic behavior simulator. The results demonstrate that superior designs can be achieved if the computational methods account for the multidisciplinary coupling effects. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Chamis, CC (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 8 TC 0 Z9 0 U1 0 U2 1 PU SOC ADVANCEMENT MATERIAL & PROCESS ENGINEERING PI COVINA PA 1161 PARKVIEW DR,, COVINA, CA 91724-3748 USA SN 0892-2624 BN 0-938994-85-9 J9 INT SAMPE TECH CONF PY 1999 VL 31 BP 405 EP 416 PG 12 WC Materials Science, Multidisciplinary; Materials Science, Composites SC Materials Science GA BP22M UT WOS:000084441300037 ER PT S AU Cano, RJ Bennett, JE Belvin, HL Jensen, BJ AF Cano, RJ Bennett, JE Belvin, HL Jensen, BJ BE Green, J Howell, DD TI Effect of molecular weight on the properties of IM7/LaRCT (TM) MPEI-5 polyimide composites SO ADVANCED MATERIALS & PROCESSES PREPARING FOR THE NEW MILLENNIUM SE INTERNATIONAL SAMPE TECHNICAL CONFERENCE SERIES LA English DT Proceedings Paper CT 31st International SAMPE Technical Conference on Advanced Materials and Processes Preparing for the New Millennium CY OCT 26-30, 1999 CL CHICAGO, IL DE composites; polyimides; prepreg; and processing AB LaRC(TM) MPEI-5 (Langley Research Center(TM) Modified Phenylethynyl Imide -5), a phenylethynyl containing aromatic polyimide which is a mixture of linear, branched and star shaped phenylethynyl containing imides, was evaluated as a matrix for high performance composites. Three molecular weight versions of the poly(amide acid) solution of LaRC(TM) MPEI-5 (theoretical number average molecular weights of 5500 g/mole, 7500 g/mole, and 9500 g/mole) in N-methypyrrolidinone were synthesized at 35% solids. Unidirectional prepreg was fabricated from these solutions and Hercules IM7 carbon fiber utilizing NASA-Langley's multipurpose prepreg machine. A composite molding cycle was developed which yielded well consolidated void-free laminates. Composite mechanical properties such as short beam shear strength, longitudinal and transverse flexural strength and flexural modulus, longitudinal tensile strength and notched and un-notched compression strengths were measured at room temperature (RT) and elevated temperatures. These mechanical properties were compared to determine the effect of molecular weight on the composite laminates. These properties were also compared to those of a similar material, LaRC(TM) MPEI-1, and to the linear, phenylethynyl containing polyimide, LaRC(TM) PETI-5. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Cano, RJ (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU SOC ADVANCEMENT MATERIAL & PROCESS ENGINEERING PI COVINA PA 1161 PARKVIEW DR,, COVINA, CA 91724-3748 USA SN 0892-2624 BN 0-938994-85-9 J9 INT SAMPE TECH CONF PY 1999 VL 31 BP 535 EP 548 PG 14 WC Materials Science, Multidisciplinary; Materials Science, Composites SC Materials Science GA BP22M UT WOS:000084441300049 ER PT S AU de Groot, W Rich, R AF de Groot, W Rich, R BE DeGroot, WA TI Performance comparison of advanced on-line sensors for steel treating atmosphere control SO ADVANCED SENSORS AND MONITORS FOR PROCESS INDUSTRIES AND THE ENVIRONMENT SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Advanced Sensors and Monitors for Process Industries and the Environment CY NOV 04-05, 1998 CL BOSTON, MA SP SPIE-Int Soc Opt Engn DE multispecies gas monitoring; in-situ gas detection; steel heat treat process control; gas atmosphere optimization AB Three novel atmosphere gas composition monitoring methods are described that could significantly improve the quality control of steel heat treat: processes. The proposed methods, gas chromatography, inter-cavity Raman analysis, and fiber-optic Raman analysis are in different stages of development but all have varying advantages over the current state of the art IR analysis. A summary description of the Raman principle is provided. Test results comparing the inter-cavity Raman analysis versus the gas chromatography analysis are given. Thf:major disadvantage of the gas chromatography is the slow response. The cast-effective inter-cavity Raman device can monitor eight species simultaneously with a response in the order of tens of milliseconds. An in-situ fiber optic Raman analysis instrument is explained and carburizing facility tests with this novel device are described. Advantages of the fiber-optic instrument are the in-situ nature and the fast response. This instrument lends itself to be readily used in applications where hostile environments (chemical corrosive species, high temperature applications) require monitoring. C1 NASA, Lewis Res Ctr, Dynacs Inc, Cleveland, OH 44135 USA. RP de Groot, W (reprint author), NASA, Lewis Res Ctr, Dynacs Inc, MS 301-3,21000 Brookpark Rd, Cleveland, OH 44135 USA. NR 8 TC 3 Z9 3 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-2996-1 J9 P SOC PHOTO-OPT INS PY 1999 VL 3535 BP 32 EP 43 DI 10.1117/12.337477 PG 12 WC Engineering, Chemical; Engineering, Industrial; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA BM50K UT WOS:000078906900004 ER PT S AU Nguyen, QV Mongia, RK Dibble, RW AF Nguyen, QV Mongia, RK Dibble, RW BE DeGroot, WA TI Real-time optical fuel-to-air ratio sensor for gas turbine combustors SO ADVANCED SENSORS AND MONITORS FOR PROCESS INDUSTRIES AND THE ENVIRONMENT SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Advanced Sensors and Monitors for Process Industries and the Environment CY NOV 04-05, 1998 CL BOSTON, MA SP SPIE-Int Soc Opt Engn DE gas turbine engines; hydrocarbon vapor sensor; jet fuel vapor sensor; active combustion control; combustor dynamics; infrared absorption; fiber optic sensor ID HYDROCARBON AB The measurement Of the temporal distribution of fuel in gas turbine combustors is important in considering pollution, combustion efficiency and combustor dynamics and acoustics. Much of the previous work in measuring fuel distributions in gas. turbine combustors has focused on the spatial aspect of the distribution. The temporal aspect however, has often been overlooked, even though it is just as important. In part, this is due to the challenges of applying real-time diagnostic techniques in a high pressure and high temperature environment. A simple and low-cost instrument that non-intrusively measures the real-time fuel-to-air ratio (FAR) in a gas turbine combustor has been developed. The device uses a dual wavelength laser absorption technique to measure the concentration of most hydrocarbon fuels such as jet fuel, methane, propane, etc. The device can be configured to use fiber optics to measure the local FAR inside a high pressure; test rig without the need for windows. Alternatively, the device can readily be used in test rigs that have existing windows without modifications. An initial application of this instrument tvas to obtain time-resolved measurements of the FAR in the premixer of a lean premixed prevaporized (LPP) combustor at inlet air pressures and temperatures as high as 17 atm @ 800 K, with Liquid JP-8 as the fuel. Results will be presented that quantitatively show the transient nature of the local FAR inside a LPP gas turbine combustor at actual operating conditions. The high speed (kHz) time resolution of this device, combined with a rugged fiber optic delivery system, should enable the realization of a flight capable active-feedback and control system for the abatement of noise and pollutant emissions in the future. Other applications that require an in-situ and time-resolved measurement of fuel vapor concentrations should also find this device to be of use. C1 NASA, Lewis Res Ctr, Turbomachinery & Prop Syst Div, Combust Branch, Cleveland, OH 44135 USA. RP Nguyen, QV (reprint author), NASA, Lewis Res Ctr, Turbomachinery & Prop Syst Div, Combust Branch, Cleveland, OH 44135 USA. NR 10 TC 4 Z9 4 U1 3 U2 7 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-2996-1 J9 P SOC PHOTO-OPT INS PY 1999 VL 3535 BP 124 EP 130 DI 10.1117/12.337458 PG 7 WC Engineering, Chemical; Engineering, Industrial; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA BM50K UT WOS:000078906900012 ER PT S AU Barnes, NP Reichle, DJ Walsh, BM AF Barnes, NP Reichle, DJ Walsh, BM BE Fejer, MM Injeyan, H Keller, U TI Solid state laser ultraviolet source SO ADVANCED SOLID-STATE LASERS SE OSA TRENDS IN OPTICS AND PHOTONICS LA English DT Proceedings Paper CT Topical Meeting on Advanced Solid-State Lasers CY JAN 31-FEB 03, 1999 CL BOSTON, MA SP Opt Soc Amer, IEEE, Lasers & Electro Opt Soc AB A laser source based on a solid state laser pump and operating at 0.304 mum was demonstrated by employing a Nd:YAG oscillator and amplifier, second harmonic, Raman scattering, and another second harmonic process. Nonlinear efficiencies of >0.6, >0.4, and >0.15, respectively, were obtained. Measured efficiencies compare well with a model which includes pulse distortion caused by the laser amplifier. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Barnes, NP (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMERICA PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1094-5695 BN 1-55752-583-8 J9 OSA TRENDS OPT PHOTO PY 1999 VL 26 BP 118 EP 122 PG 5 WC Materials Science, Characterization & Testing; Optics; Physics, Applied SC Materials Science; Optics; Physics GA BT71N UT WOS:000173833200025 ER PT S AU Lake, MS Phelps, JE Dyer, JE Caudle, DA Tam, A Escobedo, J Kasl, EP AF Lake, MS Phelps, JE Dyer, JE Caudle, DA Tam, A Escobedo, J Kasl, EP BE Roybal, W TI A deployable primary mirror for space telescopes SO ADVANCED TELESCOPE DESIGN, FABRICATION, AND CONTROL SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Advanced Telescope Design, Fabrication, and Control CY JUL 19-21, 1999 CL DENVER, CO DE precision deployment; hinge joint; latch joint; deployable structures; fabrication; space telescopes; optical instruments; microdynamics AB NASA Langley Research Center, Composite Optics, Inc., and Nyma/ADF have developed jointly a deployable primary mirror for space telescopes that combines over five years of research on deployment of optical-precision structures and over ten years of development of fabrication techniques for optical-precision composite mirror panels and structures. The deployable mirror is directly applicable to a broad class of non-imaging "lidar" (light direction and ranging) telescopes whose figure-error requirements are in the range of one to ten microns RMS. Furthermore, the minor design can be readily modified to accommodate imaging-quality reflector panels and active panel-alignment control mechanisms for application to imaging telescopes. The present paper: 1) describes the deployable mirror concept; 2) explains the status of the mirror development; and 3) provides some technical specifications for a 2.55-m-diameter, proof-of-concept mirror. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Lake, MS (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 11 TC 1 Z9 1 U1 1 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3271-7 J9 P SOC PHOTO-OPT INS PY 1999 VL 3785 BP 14 EP 25 DI 10.1117/12.367611 PG 12 WC Engineering, Aerospace; Astronomy & Astrophysics; Optics SC Engineering; Astronomy & Astrophysics; Optics GA BP12M UT WOS:000084198300002 ER PT J AU Krishnamurti, TN Tewari, M Bensman, E Han, W Zhang, Z William, WKM AF Krishnamurti, TN Tewari, M Bensman, E Han, W Zhang, Z William, WKM TI An ensemble forecast of the South China Sea monsoon SO ADVANCES IN ATMOSPHERIC SCIENCES LA English DT Article DE ensemble forecast; triangular truncation ID PHYSICAL INITIALIZATION; PARAMETERIZATION; PREDICTION; MODEL; ATMOSPHERE; MOISTURE; RATES AB This paper presents a generalized ensemble forecast procedure for the tropical latitudes. Here we propose an empirical orthogonal function-based procedure for the definition of a seven-member ensemble. The wind and the temperature fields are perturbed over the global tropics. Although the forecasts are made over the global belt with a high-resolution model, the emphasis of this study is on a South China Sea monsoon. Over this domain of the South China Sea includes the passage of a Tropical Storm, Gary, that moved eastwards north of the Philippines. The ensemble forecast handled the precipitation of this storm reasonably well. A global model at the resolution Triangular Truncation 126 waves is used to carry out these seven forecasts. The evaluation of the ensemble of forecasts is carried out via standard root mean square errors of the precipitation and the wind fields. The ensemble average is shown to have a higher skill compared to a control experiment, which was a first analysis based on operational data sets over both the global tropical and South China Sea domain. All of these experiments were subjected to physical initialization which provides a spin-up of the model rain close to that obtained from satellite and gauge-based estimates. The results furthermore show that inherently much higher skill resides in the forecast precipitation fields if they are averaged over area elements of the order of 4 degrees latitude by 4 degrees longitude squares. C1 Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. RP Krishnamurti, TN (reprint author), Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. RI AAS, AAS/C-2949-2014 NR 35 TC 2 Z9 2 U1 0 U2 4 PU CHINA OCEAN PRESS PI BEIJING PA INTERNATIONAL DEPT, 8 DA HUI SHI, BEIJING 100081, PEOPLES R CHINA SN 0256-1530 J9 ADV ATMOS SCI JI Adv. Atmos. Sci. PY 1999 VL 16 IS 2 BP 159 EP 182 DI 10.1007/BF02973080 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 245JC UT WOS:000083103000001 ER PT S AU Bansal, NP AF Bansal, NP BE Singh, JP Bansal, NP TI Tensile strength and microstructure of Hi-Nicalon fibers extracted from celsian matrix composites SO ADVANCES IN CERAMIC MATRIX COMPOSITES IV SE CERAMIC TRANSACTIONS LA English DT Proceedings Paper CT 100th Annual Meeting of the American-Ceramic-Society CY MAY 03-06, 1998 CL CINCINNATI, OH SP Amer Ceram Soc ID WEIBULL MODULUS AB Tensile strengths of uncoated and BN/SiC coated Hi-Nicalon fibers, extracted from celsian matrix composites by dissolving away the matrix in HF, were determined. Strengths of uncoated and BN/SiC coated Hi-Nicalon fibers before and after HF treatment were also measured. The elemental composition and thickness of the fiber coatings were determined using scanning Auger analysis. Microstructural analyses of the fibers and the coatings were done by SEM and TEM. The average tensile strength of uncoated Hi-Nicalon was 3.19+/-0.73 GPa with a Weibull modulus of 5.41. The Hi-Nicalon/BN/SiC fibers showed an average strength of 3.04+/-0.53 Cpa and Weibull modulus of 6.66. After HF treatments, the average strengths of the uncoated and BN/SiC coated Hi-Nicalon fibers were 2.69+/-0.67 Cpa and 2.80+/-0.53 Cpa and the Weibull moduli were 4.93 and 5.96, respectively. The BN/SiC coated fibers extracted from the celsian matrix composite exhibited a strength of 2.38+/-0.40 GPa and a Weibull modulus of 7.15. Strength of the uncoated Hi-Nicalon fibers in the composite was so severely degraded that they disintegrated into small fragments during extraction with HF. The uncoated fibers probably undergo mechanical surface damage during hot pressing of the composites. The BN layer acts as a compliant layer which protects the coated fibers from mechanical damage during composite processing. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Bansal, NP (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, WESTERVILLE, OH 43081-8720 USA SN 1042-1122 BN 1-57498-059-9 J9 CERAM TRANS PY 1999 VL 96 BP 3 EP 16 PG 14 WC Materials Science, Ceramics; Materials Science, Composites SC Materials Science GA BN02T UT WOS:000080431200001 ER PT S AU Gualtieri, JA Cromp, RF AF Gualtieri, JA Cromp, RF BE Mericsko, RJ TI Support vector machines for hyperspectral remote sensing classification SO ADVANCES IN COMPUTER-ASSISTED RECOGNITION SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 27th AIPR Workshop on Advances in Computer-Assisted Recognition CY OCT 14-16, 1998 CL WASHINGTON, D.C. SP SPIE, AIPR, Execut Comm DE support vector machine; classifier; hyperspectral; supervised learning; AVIRIS AB The Support Vector Machine provides a new way to design classification algorithms which learn from examples (supervised learning) and generalize when applied to new data. We demonstrate its success on a difficult classification problem from hyperspectral remote sensing, where we obtain performances of 96%, and 87% correct for a 4 class problem, and a 16 class problem respectively. These results are somewhat better than other recent results on the same data. A key feature of this classifier is its ability to use high-dimensional data without the usual recourse to a feature selection step to reduce the dimensionality of the data. For this application, this is important, as hyperspectral data consists of several hundred contiguous spectral channels for each exemplar. We provide an introduction to this new approach, and demonstrate its application to classification of an agriculture scene. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gualtieri, JA (reprint author), NASA, Goddard Space Flight Ctr, Code 935, Greenbelt, MD 20771 USA. NR 26 TC 21 Z9 21 U1 0 U2 9 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3054-4 J9 P SOC PHOTO-OPT INS PY 1999 VL 3584 BP 221 EP 232 DI 10.1117/12.339824 PG 12 WC Computer Science, Artificial Intelligence; Optics SC Computer Science; Optics GA BM50D UT WOS:000078902500023 ER PT S AU Newman, JC AF Newman, JC BE McClung, RC Newman, JC TI An evaluation of plasticity-induced crack closure concept and measurement methods SO ADVANCES IN FATIGUE CRACK CLOSURE MEASUREMENT AND ANALYSIS: VOL 2 SE AMERICAN SOCIETY FOR TESTING AND MATERIALS SPECIAL TECHNICAL PUBLICATION LA English DT Proceedings Paper CT 2nd Symposium on Advances in Fatigue Crack Closure Measurement and Analysis CY NOV 12-13, 1997 CL SAN DIEGO, CA SP ASTM, Comm Fatigue & Fracture E8 DE fatigue crack growth; fracture mechanics; cracks; stress-intensity factor; crack closure; plasticity; constraint ID GROWTH AB An assessment of the plasticity-induced crack closure concept is made, in light of some of the questions that have been raised on the validity of the concept, and the assumptions that have been made concerning crack-tip damage below the crack-opening stress. The impact of using other crack-tip parameters, such as the cyclic crack-tip displacement or cyclic crack-tip hysteresis energy, to model crack-growth late behavior was studied. Crack-growth simulations using the modified Dugdale crack closure model showed a close relation between traditional Delta K-eff and the cyclic crack-tip displacement (Delta delta(eff)) for an aluminum alloy and a steel over a wide range in stress ratios. Evaluations of the cyclic hysteresis energy demonstrated that the cyclic plastic damage below the crack-opening stress was negligible in the Paris crack-growth regime. Some of the standard and newly proposed remote measurement methods to determine crack-opening stresses and the "effective" crack-tip driving parameter were evaluated from crack-growth simulations made on middle-crack tension specimens. Here, analyses were conducted under both constant-amplitude and single-spike-overload conditions. A potential source of the K-max effect on crack-growth rates was studied at high stress ratios and at high stress levels for an aluminum alloy. Results showed that the ratio of K-max to K-c had a strong effect on crack-growth rates at high stress ratios and at low stress ratios for very high stress levels. The crack-closure concept and the traditional crack-growth rate equations were able to correlate and predict crack-growth rates under these extreme conditions. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Newman, JC (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 31 TC 11 Z9 11 U1 1 U2 1 PU AMERICAN SOCIETY TESTING AND MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DRIVE, W CONSHOHOCKEN, PA 19428-2959 USA SN 1040-1695 BN 0-8031-2611-5 J9 AM SOC TEST MATER PY 1999 VL 1343 BP 128 EP 144 DI 10.1520/STP15754S PG 17 WC Engineering, Mechanical; Metallurgy & Metallurgical Engineering; Microbiology SC Engineering; Metallurgy & Metallurgical Engineering; Microbiology GA BP02P UT WOS:000083908200008 ER PT J AU Cohen, SC AF Cohen, SC TI Numerical models of crustal deformation in seismic zones SO ADVANCES IN GEOPHYSICS, VOL 41 SE ADVANCES IN GEOPHYSICS LA English DT Article ID STRIKE-SLIP FAULT; WILLIAM-SOUND EARTHQUAKE; LAYERED HALF-SPACE; SAN-ANDREAS FAULT; COUPLED SUBDUCTION ZONES; NANKAI TROUGH; POSTSEISMIC DEFORMATION; STRAIN ACCUMULATION; PLATE BOUNDARIES; SOUTHWEST JAPAN C1 NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. RP Cohen, SC (reprint author), NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. NR 205 TC 38 Z9 38 U1 1 U2 6 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 USA SN 0065-2687 J9 ADV GEOPHYS PY 1999 VL 41 BP 133 EP 231 DI 10.1016/S0065-2687(08)60027-8 PG 99 WC Geosciences, Multidisciplinary SC Geology GA BR95F UT WOS:000168153500002 ER PT S AU Wheeler, KR Dhawan, AP AF Wheeler, KR Dhawan, AP BE Kearns, MS Solla, SA Cohn, DA TI Basis selection for wavelet regression SO ADVANCES IN NEURAL INFORMATION PROCESSING SYSTEMS 11 SE ADVANCES IN NEURAL INFORMATION PROCESSING SYSTEMS LA English DT Proceedings Paper CT 12th Annual Conference on Neural Information Processing Systems (NIPS) CY NOV 30-DEC 05, 1998 CL DENVER, CO ID SHRINKAGE AB A wavelet basis selection procedure is presented for wavelet regression. Both the basis and threshold are selected using cross-validation. The method includes the capability of incorporating prior knowledge on the smoothness (or shape of the basis functions) into the basis selection procedure. The results of the method are demonstrated using widely published sampled functions. The results of the method are contrasted with other basis function based methods. C1 NASA, Ames Res Ctr, Caelum Res Corp, Moffett Field, CA 94035 USA. RP Wheeler, KR (reprint author), NASA, Ames Res Ctr, Caelum Res Corp, Mail Stop 269-1, Moffett Field, CA 94035 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU M I T PRESS PI CAMBRIDGE PA FIVE CAMBRIDGE CENTER, CAMBRIDGE, MA 02142 USA SN 1049-5258 BN 0-262-11245-0 J9 ADV NEUR IN PY 1999 VL 11 BP 627 EP 633 PG 7 WC Computer Science, Artificial Intelligence SC Computer Science GA BP76H UT WOS:000086093700089 ER PT S AU Wolpert, DH Tumer, K Frank, J AF Wolpert, DH Tumer, K Frank, J BE Kearns, MS Solla, SA Cohn, DA TI Using COllective INtelligence to route internet traffic SO ADVANCES IN NEURAL INFORMATION PROCESSING SYSTEMS 11 SE ADVANCES IN NEURAL INFORMATION PROCESSING SYSTEMS LA English DT Proceedings Paper CT 12th Annual Conference on Neural Information Processing Systems (NIPS) CY NOV 30-DEC 05, 1998 CL DENVER, CO ID NETWORKS AB A COllective INtelligence (COIN) is a set of interacting reinforcement learning (RL) algorithms designed in an automated fashion so that their collective behavior optimizes a global utility function. We summarize the theory of COINs, then present experiments using that theory to design COINs to control internet traffic routing. These experiments indicate that COINs outperform all previously investigated RL-based, shortest path routing algorithms. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Wolpert, DH (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 13 TC 19 Z9 19 U1 0 U2 0 PU M I T PRESS PI CAMBRIDGE PA FIVE CAMBRIDGE CENTER, CAMBRIDGE, MA 02142 USA SN 1049-5258 BN 0-262-11245-0 J9 ADV NEUR IN PY 1999 VL 11 BP 952 EP 958 PG 7 WC Computer Science, Artificial Intelligence SC Computer Science GA BP76H UT WOS:000086093700134 ER PT S AU Mushotzky, R AF Mushotzky, R BE Holt, SS Smith, EP TI Distant large scale structures SO AFTER THE DARK AGES: WHEN GALAXIES WERE YOUNG (THE UNIVERSE AT 2 0.9 and conclude that there is strong evidence that such objects exist at z similar to 1.2. At larger redshifts the evidence is not conclusive. The number and mass of such objects is difficult to estimate at present because of their optical faintness and the limitations of present data x-ray telescopes. C1 NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. RP Mushotzky, R (reprint author), NASA, Goddard Space Flight Ctr, LHEA, Code 661, Greenbelt, MD 20771 USA. NR 36 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 1-56396-855-X J9 AIP CONF PROC PY 1999 VL 470 BP 155 EP 162 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN13D UT WOS:000080797800020 ER PT S AU Borne, KD Bushouse, H Colina, L Lucas, RA AF Borne, KD Bushouse, H Colina, L Lucas, RA BE Holt, SS Smith, EP TI Evidence for multiple mergers among Ultraluminous IR Galaxies SO AFTER THE DARK AGES: WHEN GALAXIES WERE YOUNG (THE UNIVERSE AT 2 2000) and uniform sample. From it we have learned that GRBs are isotropic on the sky and have an intensity distribution that flattens toward fainter bursts. Recently, tremendous progress has been made by measurements performed and enabled by the BeppoSAX mission. X- ray, optical and radio afterglow has been discovered for several bursts. From the accurate positions in these wavelength bands it has been possible to obtain redshifts for 3 bursts and to identify host galaxies for similar to 10 bursts. From this we now know that most, if not all, GRBs are cosmological in origin with typical distances of similar to 2 Gpc (z similar to 1). C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. EM gehrels@gsfc.nasa.gov RI Gehrels, Neil/D-2971-2012 NR 35 TC 0 Z9 0 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 1-56396-855-X J9 AIP CONF PROC PY 1999 VL 470 BP 371 EP 379 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN13D UT WOS:000080797800051 ER PT S AU Smith, EP Mather, JC AF Smith, EP Mather, JC BE Holt, SS Smith, EP TI The golden age for Near-IR astronomy SO AFTER THE DARK AGES: WHEN GALAXIES WERE YOUNG (THE UNIVERSE AT 2 70 degrees). A first contemporaneous OSSE, COMPTEL, and EGRET spectrum obtained in October 1991 covers an energy range from 50 keV up to 1 GeV. This gamma-ray broad-band spectrum was taken when Cen A was in an intermediate emission state as defined by the BATSE X-ray light-curve. The first simultaneous multiwavelength spectrum from radio to gamma-rays was measured in July 1995 when Cen A was in a low emission state (the prevailing state for the last 7 years). The different spatial and temporal resolution in the different frequency regimes produces problems in the construction and interpretation of the multiwavelength spectra. These are addressed in this paper. The detection of emission > 1 MeV makes the inclusion of such high-energy emission into models for the spectral energy distribution mandatory. (C) 1999 COSPAR. Published by Elsevier Science Ltd. C1 Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NRL, Washington, DC USA. Australia Telescope Natl Facil, Epping, NSW 2121, Australia. Univ Adelaide, Adelaide, SA 5005, Australia. ESTEC, Div Astrophys, NL-2200 AG Noordwijk, Netherlands. SRON Utrecht, NL-3584 CA Utrecht, Netherlands. Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA. RP Steinle, H (reprint author), Max Planck Inst Extraterr Phys, Postach 1603, D-85740 Garching, Germany. RI Bignall, Hayley/B-2867-2013 OI Bignall, Hayley/0000-0001-6247-3071 NR 10 TC 6 Z9 6 U1 0 U2 0 PU PERGAMON PRESS LTD PI OXFORD PA THE BOULEVARD LANGFORD LANE KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0273-1177 J9 ADV SPACE RES PY 1999 VL 23 IS 5/6 BP 911 EP 914 DI 10.1016/S0273-1177(99)00239-2 PG 4 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BN23V UT WOS:000081222000017 ER PT B AU Maghami, PG Lim, KB AF Maghami, PG Lim, KB GP AIAA AIAA TI Substructure synthesis: A controls approach SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB Substructure synthesis from a controls perspective is considered. An efficient and computationally robust method for synthesis of substructures is developed. The method considers the interface forces/moments as control inputs and redefines the synthesis problem in terms of obtaining a constant gain compensator which would ensure the connectivity requirements of the combined structure. Orthogonal similarity transformations are used to provide simplified synthesized dynamics of the combined system. The simplicity of form in transformed coordinates are exploited to effectively deal with modeling parametric and non-parametric uncertainties at substructure level. Uncertainty models of reasonable size and complexity are derived for the combined structure from those in the substructure models. C1 NASA, Langley Res Ctr, Guidance & Control Branch, Hampton, VA 23681 USA. RP Maghami, PG (reprint author), NASA, Langley Res Ctr, Guidance & Control Branch, Hampton, VA 23681 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 35 EP 42 PG 8 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000005 ER PT B AU Waszak, MR Andrisani, D AF Waszak, MR Andrisani, D GP AIAA AIAA TI Uncertainty modeling via frequency domain model validation SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB The majority of literature on robust control assumes that a design model is available and that the uncertainty model bounds the actual variations about the nominal model. However, methods for generating accurate design models have not received as much attention in the Literature. The influence of the level of accuracy of the uncertainty model on closed loop performance has received even less attention. The research reported herein is an initial step in applying and extending the concept of model validation to the problem of obtaining practical uncertainty models for robust control analysis and design applications. An extension of model validation called 'sequential validation' is presented and applied to a simple spring-mass-damper system to establish the feasibility of the approach and demonstrate the benefits of the new developments. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Waszak, MR (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 53 EP 63 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000007 ER PT B AU Kaneshige, J Bull, J Kudzia, E Burcham, FW AF Kaneshige, J Bull, J Kudzia, E Burcham, FW GP AIAA AIAA TI Propulsion control with flight director guidance as an emergency flight control system SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB The NASA Dryden Flight Research Center has developed a Propulsion Controlled Aircraft, or PCA, system in which computer-controlled engine thrust is used to provide emergency flight control capability. Using this system, F-15 and MD-II aircraft have been successfully landed without the use of primary flight controls. However aircraft, not equipped with full-authority digital engine control, require implementations of PCA technology that can be installed on existing systems. Piloted transport aircraft simulation studies at the NASA Ames Research Center have examined a "PCA Ultralite" concept, in which thrust control is provided through a combination of the autothrottle system and manual pilot control with the aid of flight director guidance. Existing autothrottle systems were found to provide adequate thrust-only pitch control for achieving a safe runway landing. However the level of difficulty of manual lateral-directional control was found to vary between aircraft. While certain flight director implementations were found to provide adequate guidance for some aircraft in regards to achieving successful runway alignment, alternate flight director implementations still need to be investigated to determine if satisfactory performance can be achieved on all PCA capable aircraft. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kaneshige, J (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 11 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 86 EP 96 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000010 ER PT B AU Green, SM Grace, MP AF Green, SM Grace, MP GP AIAA AIAA TI Conflict-free planning for en route spacing: A concept for integrating conflict probe and miles-in-trail SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB This paper describes a concept for a tool to help air traffic controllers conform to dynamic miles-in-trail (MIT) spacing restrictions. The tool will enable controllers to plan efficient spacing strategies resulting in reduced workload and fuel consumption. Integration of this tool with conflict probe will reduce the probe's false-alarm and missed-alert rates due to better knowledge of the controller's intended actions for spacing conformance. Integration will further reduce workload and fuel consumption by reducing the number of corrective clearances needed to achieve flow-rate conformance while avoiding conflicts. The purpose of this paper is to present a near-term concept for applying conflict-probe technology to enable conflict-fi ee planning with efficient MIT-spacing conformance. The paper describes the challenge associated with conflict detection and resolution under flow-rate restrictions, proposes a conflict-probe based concept for the MIT-spacing problem, and describes a prototype tool and its use through an example traffic scenario. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Green, SM (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 302 EP 312 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000031 ER PT B AU Ballin, MG Wing, DJ Hughes, MF Conway, SR AF Ballin, MG Wing, DJ Hughes, MF Conway, SR GP AIAA AIAA TI Airborne separation assurance and traffic management: Research of concepts and technology SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB To support the need for increased flexibility and capacity in the future National Airspace System, NASA is pursuing an approach that distributes air traffic separation and management tasks to both airborne and ground-based systems. Details of the distributed operations and the benefits and technical challenges of such a system are discussed. Technology requirements and research issues are outlined, and NASA's approach for establishing concept feasibility, which includes development of the airborne automation necessary to support the concept, is described. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Ballin, MG (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 313 EP 324 PG 12 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000032 ER PT B AU Gregory, IM AF Gregory, IM GP AIAA AIAA TI Modified dynamic inversion to control large flexible aircraft - What's going on? SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB High performance aircraft of the future will be designed lighter, more maneuverable, and operate over an ever expanding flight envelope. One of the largest differences from the flight control perspective between current and future advanced aircraft is elasticity. Over the last decade, dynamic inversion methodology has gained considerable popularity in application to highly maneuverable fighter aircraft, which were treated as rigid vehicles. This paper explores dynamic inversion application to an advanced highly flexible aircraft. An initial application has been made to a large flexible supersonic aircraft. In the course of controller design for this advanced vehicle, modifications were made to the standard dynamic inversion methodology. The results of this application were deemed rather promising. An analytical study has been undertaken to better understand the nature of the made modifications and to determine its general applicability. This paper presents the results of this initial analytical look at the modifications to dynamic inversion to control large flexible aircraft. C1 NASA, Langley Res Ctr, Flight Dynam & Control Div, Hampton, VA 23665 USA. RP Gregory, IM (reprint author), NASA, Langley Res Ctr, Flight Dynam & Control Div, Hampton, VA 23665 USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 392 EP 402 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000041 ER PT B AU Ostroff, AJ Bacon, BJ AF Ostroff, AJ Bacon, BJ GP AIAA AIAA TI Force and moment approach for achievable dynamics using nonlinear dynamic inversion SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB This paper describes a general form of nonlinear dynamic inversion control for use in a generic nonlinear simulation to evaluate candidate augmented aircraft dynamics. The implementation is specifically tailored to the task of quickly assessing an aircraft's control power requirements and defining the achievable dynamic set. The achievable set is evaluated while undergoing complex mission maneuvers, and perfect tracking will be accomplished when the desired dynamics are achievable. Variables are extracted directly from the simulation model each iteration, so robustness is not an issue. Included in this paper is a description of the implementation of the forces and moments from simulation variables, the calculation of control effectiveness coefficients, methods for implementing different types of aerodynamic and thrust vectoring controls, adjustments for control effector failures, and the allocation approach used. A few examples illustrate the perfect tracking results obtained. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Ostroff, AJ (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 11 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 424 EP 434 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000044 ER PT B AU Morelli, EA AF Morelli, EA GP AIAA AIAA TI Real-time parameter estimation in the frequency domain SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB A method for real-time estimation of parameters in a linear dynamic state space model was developed and studied. The application is aircraft dynamic model parameter estimation from measured data in flight for indirect adaptive or reconfigurable control. Equation error in the frequency domain was used with a recursive Fourier transform for the real-time data analysis. Linear and nonlinear simulation examples and flight test data from the F-18 High Alpha Research Vehicle (HARV) were used to demonstrate that the technique produces accurate model parameter estimates with appropriate error bounds. Parameter estimates converged in less than 1 cycle of the dominant dynamic mode natural frequencies, using control surface inputs measured in flight during ordinary piloted maneuvers. The real-time parameter estimation method has low computational requirements, and could be implemented aboard an aircraft in real time. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Morelli, EA (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 16 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 477 EP 487 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000049 ER PT B AU Burken, JJ Lu, P Wu, ZL AF Burken, JJ Lu, P Wu, ZL GP AIAA AIAA TI Reconfigurable flight control designs with application to the X-33 vehicle SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut ID SYSTEMS AB Two methods for control system reconfiguration have been investigated. The first method is a robust servomechanism control approach (optimal tracking problem) that is a generalization of the classical proportional-plus-integral control to multiple input-multiple output systems. The second method is a control-allocation approach based on a quadratic programming formulation. A globally convergent fixed-point iteration algorithm has been developed to make onboard implementation of this method feasible. These methods have been applied to reconfigurable entry flight control design for the X-33 vehicle. Examples presented demonstrate simultaneous tracking of angle-of-attack and roll angle commands during failures of the right body flap actuator. Although simulations demonstrate success of the first method in most cases, the control-allocation method appears to provide uniformly better performance in all cases. C1 NASA, Dryden Flight Res Ctr, Edwards, CA USA. RP Burken, JJ (reprint author), NASA, Dryden Flight Res Ctr, Edwards, CA USA. NR 9 TC 1 Z9 1 U1 1 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 951 EP 965 PG 15 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000099 ER PT B AU Atkins, S Hansman, RJ AF Atkins, S Hansman, RJ GP AIAA AIAA TI Calculating dependent surveillance update rates by modeling the time-dependence of information value SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB The time-dependence of information has historically been managed though manual procedures, typically developed heuristically, specifying how frequently or under what conditions aging information should be refreshed. In the design of Automatic Dependent Surveillance (ADS) applications, when aircraft should automatically broadcast state information (e.g., position, velocity, or intent) must be addressed more rigorously. To answer questions about how frequently or under what conditions aging information should be updated, when the cost of seeking information must be accounted, a novel model of time-dependent information value is developed for a class of proceduralized decision problems, common in aviation. The model combines elements of classic, time-invariant information value theory, which is incapable of modeling the relationship between information value and information age, with estimation techniques. The time-dependent information value model is applied to investigate the rate at which aircraft should broadcast state information in an ADS environment. Results are presented for aircraft flying on parallel trajectories as well as on crossing trajectories. Results also provide general insight into the time-dependence of information value and its implications on information management processes. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Atkins, S (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 1058 EP 1068 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000109 ER PT B AU Coppenbarger, RA AF Coppenbarger, RA GP AIAA AIAA TI En route climb trajectory predicition enhancement using airline flight-planning information SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB Software decision support tools that assist controllers with the management of air traffic are dependent upon the ability to accurately predict future aircraft positions. Trajectory predictions in en route airspace rely upon the availability of aircraft state, aircraft performance, pilot intent, and atmospheric data. The use of real-time airline information for improving ground-based trajectory predictions has been a recent focus in the development of the Center-TRACON Automation System (CTAS) at NASA Ames. This paper studies the impact of airline flight-planning data on CTAS en route climb trajectory prediction accuracy. The climb trajectory synthesis process is first described along with existing input data. Flight-planning data parameters, available from a typical airline operations center, are then discussed along with their potential usefulness to CTAS. Results are then presented to show the significant impact of airline-provided takeoff weight, speed-profile, and thrust calibration data on CTAS climb trajectory prediction performance. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Coppenbarger, RA (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 8 TC 0 Z9 1 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 1077 EP 1087 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000111 ER PT B AU Lim, KB AF Lim, KB GP AIAA AIAA TI A methodology for model validation and uncertainty modeling for linear multivariable robust control SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB This is a heuristically oriented tutorial paper with the user in mind. It describes a specific viewpoint in the use of model validation to construct uncertainty models for robust control analysis and design of practical systems. Following an overview of the supporting theory, two examples are given, the first involves a simulation of a transparent system while the second example describes experimental results. C1 NASA, Langley Res Ctr, Guidance & Control Branch, Hampton, VA 23665 USA. RP Lim, KB (reprint author), NASA, Langley Res Ctr, Guidance & Control Branch, Hampton, VA 23665 USA. NR 2 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 1145 EP 1155 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000118 ER PT B AU Carter, J Stephenson, M AF Carter, J Stephenson, M GP AIAA AIAA TI Initial flight test of the production support flight control computers at NASA Dryden Flight Research Center SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB The NASA Dryden Flight Research Center has completed the initial flight test of a modified set of F/A-18 flight control computers that gives the aircraft a research control law capability. The production support flight control computers (PSFCC) provide an increased capability for flight research in the control law, handling qualifies, and flight systems areas. The PSFCC feature a research flight control processor that is "piggybacked" onto the baseline F/A-18 flight control system. This research processor allows for pilot selection of research control law operation in flight. To validate flight operation, a replication of a standard F/A-18 control law was programmed into the research processor and flight-tested over a limited envelope. This paper provides a brief description of the system, summarizes the initial flight test of the PSFCC, and describes future experiments for the PSFCC. C1 NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. RP Carter, J (reprint author), NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. NR 5 TC 0 Z9 0 U1 1 U2 1 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 1199 EP 1212 PG 14 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000123 ER PT B AU Whorton, MS Lin, CF Bao, PA Braasch, S AF Whorton, MS Lin, CF Bao, PA Braasch, S GP AIAA AIAA TI Optimized fuzzy logic vibration control of a flexible space structure SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut ID CONTROL-SYSTEMS AB A fuzzy logic based vibration control system for a multi-input, multi-output (MIMO) STABLE platform system has been studied in this paper. In order to avoid the complexity of designing an MIMO fuzzy control system, a standard fuzzy logic control frame has been proposed, which converts the different universes of discourse for different input and output variables into a standard universe of discourse, by selecting appropriate scaling factors for each of the fuzzy logic controllers. An MIMO fuzzy logic controller is converted into a scaling factor optimization problem by this standard fuzzy logic controller frame. At the same time, the existence of co-situated sensor/actuator pairs allows the designer to create only six fuzzy logic controllers for six sensor/actuator pairs. The position sensor measurements and their derivatives serve as the fuzzy logic controller inputs, which generate the control forces for the corresponding actuators. The resulting vibration control system is robust against external disturbance forces and parametric variations. In addition, two new FLC plus Integral control configurations improve the robustness of fuzzy logic based vibration control systems against extended applications of external disturbance forces. Simulation results demonstrate the improved performance and robustness of the designed STABLE platform fuzzy logic based vibration control system. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Whorton, MS (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 1416 EP 1423 PG 8 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000144 ER PT B AU Chatterji, GB AF Chatterji, GB GP AIAA AIAA TI Short-term trajectory prediction methods SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB This paper addresses the problem of aircraft state estimation and use of these estimates to predict the future state of the aircraft. The aircraft states are groundspeed, track angle and the horizontal components of the position vector with respect to an inertial frame of reference. In the current air traffic control system, the host computer provides the state estimates based on the track data obtained from primary and secondary surveillance radars. The groundspeed and track angle estimates provided by the host computer are very noisy. Smoothing techniques that are employed for generating smooth estimates also introduce large lag in the estimates. Algorithms which provide smooth estimates without introducing large delays are therefore needed. Three such algorithms are described in the paper. The first algorithm is a Kalman filter. The second algorithm is based on a Proportional-Integral-Derivative controller design using a nonlinear inverse model. The third algorithm is a hybrid algorithm which combines a low-pass filter with a least squares estimator. All three estimators use the surveillance data provided by the Air Route Traffic Control Center host computer. To verify the performance of these algorithms, the states estimated by these algorithms are compared with the Global Positioning System (GPS) based states recorded during the flight test. It is shown that these algorithms are able to provide more accurate estimates compared to those provided by the host computer without introducing significant delays. The second part of the paper examines the accuracy of short-term tactical trajectory prediction using the improved state estimates generated via these algorithms. The short-term trajectory prediction is done by propagating the estimated states into the future by integrating the equations of motion. The prediction error statistics for the curved and straight portions of the flight trajectory with reference to the GPS-based measurements are discussed. The estimation algorithms described in this paper will be especially useful in situations when the aircraft deviates from its intended flight plan, and in the future distributed air ground systems in which the surveillance information will be uplinked to the cockpit and cockpit-based state estimation and trajectory prediction tools will be used for self separation. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Chatterji, GB (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 13 TC 0 Z9 0 U1 1 U2 2 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 1496 EP 1506 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000151 ER PT B AU Mesbahi, M Hadaegh, FY AF Mesbahi, M Hadaegh, FY GP AIAA AIAA TI Formation flying control of multiple spacecraft: Graph theoretic properties and switching schemes SO AIAA GUIDANCE, NAVIGATION, AND CONTROL CONFERENCE, VOLS 1-3: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Guidance, Navigation, and Control Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut DE formation flying; linear matrix inequality; logic-based switching; graph theory AB We present several results on the leader-following (LF) paradigm in the formation flying of multiple spacecraft in free space. In this direction, ideas from elementary graph theory and linear matrix inequalities are combined with logic-based switching to shed light on the various control designs which are feasible using the leader-following mechanism for various formation scenarios. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM mesbahi@hafez.jpl.nasa.gov; fred.y.hadaegh@jpl.nasa.gov NR 16 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-299-6 PY 1999 BP 1585 EP 1595 PG 11 WC Engineering, Aerospace SC Engineering GA BP87S UT WOS:000086465000160 ER PT J AU Arian, E Salas, MD AF Arian, E Salas, MD TI Admitting the inadmissible: Adjoint formulation for incomplete cost functionals in aerodynamic optimization SO AIAA JOURNAL LA English DT Article AB The adjoint equations are derived for problems in aerodynamic optimization that are improperly considered as inadmissible. For example, a cost functional that depends on the density, rather than on the pressure, is considered inadmissible for an optimization problem governed by the Euler equations. We show that for such problems additional terms should be included in the Lagrangian functional when deriving the adjoint equations, These terms are obtained from the restriction of the interior partial differential equation to the control surface. Demonstrations of the explicit derivation of the adjoint equations for inadmissible cost functionals are given for the potential, Euler, and Navier-Stokes equations. C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23665 USA. RP Arian, E (reprint author), NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23665 USA. NR 13 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 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD JAN PY 1999 VL 37 IS 1 BP 37 EP 44 DI 10.2514/2.690 PG 8 WC Engineering, Aerospace SC Engineering GA 157NR UT WOS:000078069000004 ER PT B AU Lehmer, RD Chung, WWY AF Lehmer, RD Chung, WWY GP AIAA AIAA TI Image dynamic measurement system (IDMS-2) for flight simulation fidelity verification SO AIAA MODELING AND SIMULATION TECHNOLOGIES CONFERENCE: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Modeling and Simulation Technologies Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB The fidelity of human-in-the-loop flight simulators is critically dependent upon maintaining a short time interval in the response of the motion and visual cues to a change in the simulated aircraft response. The delay in the visual and motion cues is of particular concern in research and development flight simulators because the pilot perceives the simulated aircraft response and performance primarily through these simulation cues. While the delay in the motion base response can be monitored with accelerometers and other sensors, the measurement of the delay in the visual system response time requires an instrument for analyzing the video data in real-time. The Image Dynamic Measurement System, Mark II (IDMS-2) has been developed at NASA's Ames Research Center to analyze the output video of an image generator and to produce analog and digital outputs proportional to the position of a predefined target image. The IDMS-2 is designed to support a wide variety of video sources and scan rates and has an adaptive timing system that allows for analysis of the target image during each video field, independent of scan rate or interlace factor. In addition, the logic contained within the IDMS-2 prevents erroneous data from being generated if the instrument is not configured properly for the video source being analyzed. In this paper, the design and implementation of the IDMS-2 instrument will be presented. The use of the IDMS-2 in verifying the visual cueing fidelity of the Vertical Motion Simulator at Ames Research Center will also be discussed. C1 NASA, Ames Res Ctr, Logicon Informat Syst & Serv, Moffett Field, CA 94035 USA. RP Lehmer, RD (reprint author), NASA, Ames Res Ctr, Logicon Informat Syst & Serv, Moffett Field, CA 94035 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-301-1 PY 1999 BP 137 EP 143 PG 3 WC Engineering, Aerospace; Computer Science, Software Engineering SC Engineering; Computer Science GA BP86K UT WOS:000086446300014 ER PT B AU Schroeder, JA Chung, WWY Hess, RA AF Schroeder, JA Chung, WWY Hess, RA GP AIAA AIAA TI Spatial frequency and platform motion effects on helicopter altitude control SO AIAA MODELING AND SIMULATION TECHNOLOGIES CONFERENCE: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Modeling and Simulation Technologies Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut ID PERCEIVED VELOCITY; PERCEPTION; SPEED AB An experiment examined how visual scene and platform motion variations affected a pilot's ability to perform altitude changes. Pilots controlled a helicopter model in the vertical axis and moved between two points 32-ft apart in a specified time. Four factors were varied: visual scene spatial frequency, visual scene background, motion filter gain, and motion filter natural frequency. Drawing alternating black and white stripes of varying widths between the two extreme altitude points varied visual scene spatial frequency. Visual scene background varied by either drawing the stripes to fill the entire field-of-view or by placing the stripes on a narrow pole with a natural sky and ground plane behind the pole. Both the motion filter gain and natural frequency were varied in the motion platform command software. Five pilots evaluated all combinations of the visual and motion variations. The results showed that only the motion filter natural frequency and visual scene background affected pilot performance and their subjective ratings. No significant effects of spatial frequency or motion system gain were found for the values examined in this tracking task. A previous motion fidelity criterion was found to still be a reasonable predictor of motion fidelity. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schroeder, JA (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 26 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-301-1 PY 1999 BP 171 EP 181 PG 5 WC Engineering, Aerospace; Computer Science, Software Engineering SC Engineering; Computer Science GA BP86K UT WOS:000086446300018 ER PT B AU Tran, DT Chung, WW Mikula, J AF Tran, DT Chung, WW Mikula, J GP AIAA AIAA TI Preliminary investigation of the motion fidelity criterion for a pitch-longitudinal translational task SO AIAA MODELING AND SIMULATION TECHNOLOGIES CONFERENCE: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Modeling and Simulation Technologies Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB While the ground-based flight simulation community is increasingly interested in determining the required motion fidelity to meet mission requirements, little has been done to determine the motion fidelity requirements for the pitch and longitudinal degrees-of-freedom. Typically, the pitch and longitudinal motion fidelity is determined by following the same criteria as the roll and lateral degrees-of-freedom. However, pitch visual cues are typically different from roll visual cues. Since visual and motion cues are known to interact, investigation of the pitch and longitudinal motion fidelity criteria is warranted This investigation used a helicopter model with satisfactory handling qualities to translate longitudinally between two points 20 feet apart. A simulation cueing baseline was developed such that the motion and visual cues were one to one. Motion cueing reductions were subsequently evaluated from this baseline case. Two angular motion and eleven translational motion configurations were flown by four test pilots. Results indicate that as longitudinal phase distortion is increased, motion fidelity ratings decreases and also as longitudinal motion gain decreases, the motion fidelity ratings also decrease. Both results are consistent with the roll-lateral motion requirements. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Tran, DT (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-301-1 PY 1999 BP 503 EP 511 PG 5 WC Engineering, Aerospace; Computer Science, Software Engineering SC Engineering; Computer Science GA BP86K UT WOS:000086446300055 ER PT B AU Cunningham, K AF Cunningham, K GP AIAA AIAA TI Use of the Mediator Design Pattern in the LaSRS plus plus framework SO AIAA MODELING AND SIMULATION TECHNOLOGIES CONFERENCE: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Modeling and Simulation Technologies Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB Software design patterns are effective, efficient, established solutions to common software design problems. The Mediator Design Pattern is a particularly simple design pattern. It is used extensively in the NASA Langley Standard Real-Time Simulation in C++ (LaSRS++) Framework. The Mediator Design Pattern acts as an information "broker" between the components of a system. The use of the Mediator Design Pattern is a simple means by which re-usability, simplicity and testability of flight simulation software can be obtained. C1 NASA, Langley Res Ctr, Unisys Corp, Hampton, VA 23681 USA. RP Cunningham, K (reprint author), NASA, Langley Res Ctr, Unisys Corp, MS 169, Hampton, VA 23681 USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-301-1 PY 1999 BP 531 EP 537 PG 3 WC Engineering, Aerospace; Computer Science, Software Engineering SC Engineering; Computer Science GA BP86K UT WOS:000086446300058 ER PT B AU Geyer, DW AF Geyer, DW GP AIAA AIAA TI The use of multiple threads in an object-oriented real-time simulation SO AIAA MODELING AND SIMULATION TECHNOLOGIES CONFERENCE: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Modeling and Simulation Technologies Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB As real-time simulations become more complex, a single processor is no longer sufficient to perform all of the necessary computations. It becomes desirable to execute independent sections of a real-time simulation on different processors. The traditional approach to utilizing multiple processors on a symmetric multiprocessor machine involves writing a program composed of one process per processor that interact through shared memory. A program that uses threads can utilize multiple processors without the overhead of full processes or the use of a cumbersome shared memory mechanism. This is due to the fact that threads implicitly share a common address space. A multithreaded real-time program is organized as a main thread controlling zero or more auxiliary real-time threads. Each processor to be used for real-time computations is assigned a single auxiliary real-time thread. The main thread monitors the real-time clock and informs the auxiliary threads when the clock ticks. An auxiliary thread can also be used to monitor and control the simulation via a graphical user interface (GUI). These object-oriented designs were implemented in C++ for the NASB Langley Standard Real-Time Simulation (LaSRS++) Application Framework. C1 NASA, Langley Res Ctr, Unisys Corp, Hampton, VA 23681 USA. RP Geyer, DW (reprint author), NASA, Langley Res Ctr, Unisys Corp, MS 169, Hampton, VA 23681 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-301-1 PY 1999 BP 538 EP 546 PG 3 WC Engineering, Aerospace; Computer Science, Software Engineering SC Engineering; Computer Science GA BP86K UT WOS:000086446300059 ER PT B AU Glaab, PC Madden, MM AF Glaab, PC Madden, MM GP AIAA AIAA TI A generic object-oriented implementation for flight control systems SO AIAA MODELING AND SIMULATION TECHNOLOGIES CONFERENCE: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Modeling and Simulation Technologies Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB This paper presents a design for a generic flight control system (FCS) architecture that breaks the control system into a coupled interaction of laws and devices with a standardized method for execution. Laws generally are computational components that generate commands as outputs, and any number of laws can be isolated and registered on a list in any order for execution. Control devices are code components that receive the command inputs and use additional computations to generate device outputs, such as the servoactuator positions for the control of surfaces. Any number of devices are allowable for a given flight control system and are registered in list format for execution. This method allows for both simplistic FCS implementations and highly complex control systems without changing the architectural requirements of the high level executive. By separating the laws from the devices, special case handling required for control law bypassing (such as that required for direct-drive surface testing and linear analysis) is easily handled at the execution level. No special code support is required internal to the laws. C1 NASA, Langley Res Ctr, Unisys Corp, Hampton, VA 23681 USA. RP Glaab, PC (reprint author), NASA, Langley Res Ctr, Unisys Corp, Mail Stop 125N, Hampton, VA 23681 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-301-1 PY 1999 BP 547 EP 553 PG 3 WC Engineering, Aerospace; Computer Science, Software Engineering SC Engineering; Computer Science GA BP86K UT WOS:000086446300060 ER PT B AU Kenney, PS Geyer, DW AF Kenney, PS Geyer, DW GP AIAA AIAA TI Using abstraction to create a portable object-oriented simulation SO AIAA MODELING AND SIMULATION TECHNOLOGIES CONFERENCE: A COLLECTION OF TECHNICAL PAPERS LA English DT Proceedings Paper CT AIAA Modeling and Simulation Technologies Conference CY AUG 09-11, 1999 CL PORTLAND, OR SP Amer Inst Aeronaut & Astronaut AB A common problem faced in the design of an object-oriented simulation is that there are many different groups of end users of the simulation framework. Each group invariably has a different computer platform on which to run the simulation. In an attempt to satisfy all of these different groups, a simulation framework should be designed to be portable so that it can be operated on as many different platforms as possible. The purpose of this paper is to describe several designs that isolate the framework from the platform dependent services required by a simulation. C1 NASA, Langley Res Ctr, Unisys Corp, Hampton, VA 23681 USA. RP Kenney, PS (reprint author), NASA, Langley Res Ctr, Unisys Corp, Mail Stop 169, Hampton, VA 23681 USA. NR 16 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUTICS & ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DR, STE 500, RESTON, VA 20191-4344 USA BN 1-56347-301-1 PY 1999 BP 554 EP 562 PG 3 WC Engineering, Aerospace; Computer Science, Software Engineering SC Engineering; Computer Science GA BP86K UT WOS:000086446300061 ER PT S AU Pavri, B Bearman, G Margolis, J Moynihan, P Liu, K AF Pavri, B Bearman, G Margolis, J Moynihan, P Liu, K BE Leonelli, J Althouse, ML TI Development of radiometric system models for performance comparison of proposed instruments SO AIR MONITORING AND DETECTION OF CHEMICAL AND BIOLOGICAL AGENTS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Air Monitoring and Detection of Chemical and Biological Agents CY NOV 02-03, 1998 CL BOSTON, MA SP Soc Photo Opt Instrumentat Engineers DE radiometric modeling; performance modeling; systems engineering AB Radiometric models have been used to optimize instrument design or evaluate impacts of changes to the design during integration and test. Tradeoffs such as spectral and spatial resolution, telescope and spectrometer temperature, aperture, f/No., integration time, optics and filter transmissions, and so forth can be quickly changed to evaluate changes to the signal/noise ratio or other performance metrics. An alternative use of such models is to identify promising instrument proposals for further study. A series of models were constructed to evaluate general instrument designs as an illustration of this process. These models included two grating spectrometers (whiskbroom and pushbroom) and a spatially modulated interferometer. All were given a common set of radiometric inputs and telescope optical prescription. Results of the modeling illustrate the performance differences between instrument types, although signal/noise predictions should be evaluated along with other parameters such as manufacturability, precision of calibration, and so forth. Such modeling allows instrument developers to demonstrate to potential customers improvements in their instruments, and the advantages of their product over other instruments for a specific application. Ifa common set of inputs is used for the different instrument models, this technique gives customers one metric with which to evaluate the disparate proposals. C1 Jet Prop Lab, Pasadena, CA 90041 USA. RP Pavri, B (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 90041 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-2994-5 J9 P SOC PHOTO-OPT INS PY 1999 VL 3533 BP 15 EP 24 DI 10.1117/12.336866 PG 10 WC Environmental Sciences; Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Optics SC Environmental Sciences & Ecology; Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Optics GA BM42U UT WOS:000078691100003 ER PT S AU Margolis, JS Liu, KY Moynihan, PI AF Margolis, JS Liu, KY Moynihan, PI BE Leonelli, J Althouse, ML TI Spectroscopic observations of low-lying gas clouds: sensitivity of detection by method of covariance matrix SO AIR MONITORING AND DETECTION OF CHEMICAL AND BIOLOGICAL AGENTS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Air Monitoring and Detection of Chemical and Biological Agents CY NOV 02-03, 1998 CL BOSTON, MA SP Soc Photo Opt Instrumentat Engineers DE spectroscopy; retrievals; thermal IR; plumes; detection AB The sensitivity of spectroscopic detection of low-lying gas clouds by an arbitrary spectrometer may be determined by simulating the observation using a high spectral resolution radiative transfer code. The instrumental characteristics may be superimposed on the simulation and the accuracy of the retrieval of the desired parameters may be estimated by use of the covariance matrix. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Margolis, JS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 183-301, Pasadena, CA 91109 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-2994-5 J9 P SOC PHOTO-OPT INS PY 1999 VL 3533 BP 25 EP 32 DI 10.1117/12.336867 PG 8 WC Environmental Sciences; Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Optics SC Environmental Sciences & Ecology; Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Optics GA BM42U UT WOS:000078691100004 ER PT J AU Huber, H Junen, K Pinkleton, D AF Huber, H Junen, K Pinkleton, D TI NASA saves significant development costs by using commercially available field computer SO AIRCRAFT ENGINEERING AND AEROSPACE TECHNOLOGY LA English DT Article DE aerospace; computers; data collection; NASA C1 NASA, MSFC, Birmingham, MI USA. Boeing N Amer, Huntsville, AL USA. RP Huber, H (reprint author), NASA, MSFC, Birmingham, MI USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MCB UNIV PRESS LTD PI BRADFORD PA 60/62 TOLLER LANE, BRADFORD BD8 9BY, W YORKSHIRE, ENGLAND SN 0002-2667 J9 AIRCR ENG AEROSP TEC JI Aircr. Eng. Aerosp. Technol. PY 1999 VL 71 IS 2 BP 162 EP 164 PG 3 WC Engineering, Aerospace SC Engineering GA 195JN UT WOS:000080247200009 ER PT J AU van Dam, CP Shaw, SG Vander Kam, JC Rudolph, PKC Kinney, D AF van Dam, CP Shaw, SG Vander Kam, JC Rudolph, PKC Kinney, D TI Aero-mechanical design of high-lift systems SO AIRCRAFT ENGINEERING AND AEROSPACE TECHNOLOGY LA English DT Article DE aircraft industry; aerodynamics AB In today's highly competitive and economically driven commercial aviation market, the trend is to make aircraft systems simpler and to design and develop them faster resulting in lower production and operational costs. One such system is the high-lift system. A methodology has been developed which merges aerodynamic data with kinematic analysis of the trailing-edge flap mechanism with minimum mechanism definition required. This methodology provides quick and accurate aerodynamic performance prediction of the flap deployment mechanism early on in the high-lift system preliminary design stage. Sample analysis results for four different deployment mechanisms are presented as, well as descriptions of the aerodynamic and mechanism data required for evaluation. Extensions to interactive design capabilities are also discussed. C1 Univ Calif Davis, Dept Mech & Aeronaut Engn, Davis, CA 95616 USA. PKCR Inc, Seattle, WA USA. NASA, Ames Res Ctr, Syst Anal Branch, Moffett Field, CA 94035 USA. RP van Dam, CP (reprint author), Univ Calif Davis, Dept Mech & Aeronaut Engn, Davis, CA 95616 USA. NR 10 TC 3 Z9 3 U1 0 U2 4 PU MCB UNIV PRESS LTD PI BRADFORD PA 60/62 TOLLER LANE, BRADFORD BD8 9BY, W YORKSHIRE, ENGLAND SN 0002-2667 J9 AIRCR ENG AEROSP TEC JI Aircr. Eng. Aerosp. Technol. PY 1999 VL 71 IS 5 BP 436 EP 443 PG 8 WC Engineering, Aerospace SC Engineering GA 255PT UT WOS:000083679000001 ER PT J AU Han, D Kim, YS Noz, ME AF Han, D Kim, YS Noz, ME TI Illustrative example of Feynman's rest of the universe SO AMERICAN JOURNAL OF PHYSICS LA English DT Article ID 2-PHOTON QUANTUM OPTICS; SQUEEZED STATES; TRANSFORMATIONS; OSCILLATORS; FORMALISM; MODEL AB Coupled harmonic oscillators occupy an important place in physics teaching. It is shown that they can be used for illustrating an increase in entropy caused by limitations in measurement. In the system of coupled oscillators, it is possible to make the measurement on one oscillator while averaging over the degrees of freedom of the other oscillator without measuring them. It is shown that such a calculation would yield an increased entropy in the observable oscillator. This example provides a clarification of Feynman's rest of the universe. (C) 1999 American Association of Physics Teachers. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. NYU, Dept Radiol, New York, NY 10016 USA. RP Han, D (reprint author), NASA, Goddard Space Flight Ctr, Code 935, Greenbelt, MD 20771 USA. NR 32 TC 43 Z9 43 U1 0 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 USA SN 0002-9505 J9 AM J PHYS JI Am. J. Phys. PD JAN PY 1999 VL 67 IS 1 BP 61 EP 66 DI 10.1119/1.19192 PG 6 WC Education, Scientific Disciplines; Physics, Multidisciplinary SC Education & Educational Research; Physics GA 151EQ UT WOS:000077708100008 ER PT J AU Dehority, W Halloran, BP Bikle, DD Curren, T Kostenuik, PJ Wronski, TJ Shen, Y Rabkin, B Bouraoui, A Morey-Holton, E AF Dehority, W Halloran, BP Bikle, DD Curren, T Kostenuik, PJ Wronski, TJ Shen, Y Rabkin, B Bouraoui, A Morey-Holton, E TI Bone and hormonal changes induced by skeletal unloading in the mature male rat SO AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM LA English DT Article DE aging; disuse osteoporosis; mechanical loading of bone ID BED-REST; SIMULATED WEIGHTLESSNESS; CANCELLOUS BONE; TIME COURSE; IMMOBILIZATION; 1,25-DIHYDROXYVITAMIN-D; OVARIECTOMY; INHIBITION; ADAPTATION; RECOVERY AB To determine whether the rat hindlimb elevation model can be used to study the effects of spaceflight and loss of gravitational loading on bone in the adult animal, and to examine the effects of age on bone responsiveness to mechanical loading, we studied 6-mo-old rats subjected to hindlimb elevation for up to 5 wk. Loss of weight bearing in the adult induced a mild hypercalcemia, diminished serum 1,25-dihydroxyvitamin D, decreased vertebral bone mass, and blunted the otherwise normal increase in femoral mass associated with bone maturation. Unloading decreased osteoblast numbers and reduced periosteal and cancellous bone formation but had no effect on bone resorption. Mineralizing surface, mineral apposition rate, and bone formation rate decreased during unloading. Our results demonstrate the utility of the adult rat hindlimb elevation model as a means of simulating the loss of gravitational loading on the skeleton, and they show that the effects of nonweight bearing are prolonged and have a greater relative effect on bone formation in the adult than in the young growing animal. C1 Vet Affairs Med Ctr, Endocrine Res Unit 111N, Div Endocrinol, San Francisco, CA 94121 USA. Univ Calif San Francisco, Dept Med, San Francisco, CA 94121 USA. Univ Calif San Francisco, Dept Physiol, San Francisco, CA 94121 USA. NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Univ Florida, Coll Vet Med, Dept Physiol Sci, Gainesville, FL 32610 USA. RP Halloran, BP (reprint author), Vet Affairs Med Ctr, Endocrine Res Unit 111N, Div Endocrinol, San Francisco, CA 94121 USA. NR 42 TC 94 Z9 98 U1 0 U2 4 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0193-1849 J9 AM J PHYSIOL-ENDOC M JI Am. J. Physiol.-Endocrinol. Metab. PD JAN PY 1999 VL 276 IS 1 BP E62 EP E69 PG 8 WC Endocrinology & Metabolism; Physiology SC Endocrinology & Metabolism; Physiology GA 157UL UT WOS:000078080000007 PM 9886951 ER PT J AU Ransom, B Bennett, RH Baerwald, R Hulbert, VH Burkett, PJ AF Ransom, B Bennett, RH Baerwald, R Hulbert, VH Burkett, PJ TI In situ conditions and interactions between microbes and minerals in fine-grained marine sediments: A TEM microfabric perspective SO AMERICAN MINERALOGIST LA English DT Article ID ELECTRON-MICROSCOPY; SOIL-MICROORGANISMS; ORGANIC-MATTER; BACTERIA; SURFACE; ULTRASTRUCTURE; COLONIZATION; ENVIRONMENTS; AGGREGATION; GLYCOCALYX AB Microbes, their exocellular secretions, and their impact on the mineralogy and microfabric of fine-grained continental margin sediments were investigated by transmission electron microscopy. Techniques were used that retained the in situ spatial relations of both bio-organic and mineralogical constituents. Photomicrographs were taken of characteristic mineral-microbe associations in the first meter of burial at conditions ranging from aerobic to anaerobic. Single-celled prokaryotes, prokaryotic colonies, and eukaryotic organisms were observed as were motile, sessile, and predatory species. Bacterial cells dominate the assemblage. The most commonly observed mineral-biological interaction was the surrounding, or close association, of isolated heterotrophic bacterial cells by clay minerals. Almost without exception, the external surfaces of the bacteria were covered with secreted exocellular slimes composed of cross-linked polysaccharide fibrils. These fibrils act to bind sediment grains into relatively robust microaggregates, roughly less than or equal to 25 mu m in diameter. These exocellular polymers can significantly impact the interaction between microbes and minerals, as well as the chemical and physical transport of fluids and dissolved aqueous species through the sediment. Although pore water chemical profiles from the field sites studied have dissolved Fe and Mn, no close association was found between the microbes imaged and precipitated metal oxyhydroxides or other authigenic minerals, such as is commonly reported from laboratory cultures. C1 Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. Seaprobe Inc, Picayune, MS 39566 USA. Univ New Orleans, Dept Biol, New Orleans, LA 70148 USA. Resource Dynam, Florissant, MO 63031 USA. USN, Res Lab, Stennis Space Ctr, Stennis Space Ctr, MS 39529 USA. RP Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. EM bransom@ucsd.edu NR 75 TC 31 Z9 33 U1 2 U2 11 PU MINERALOGICAL SOC AMER PI CHANTILLY PA 3635 CONCORDE PKWY STE 500, CHANTILLY, VA 20151-1125 USA SN 0003-004X EI 1945-3027 J9 AM MINERAL JI Am. Miner. PD JAN-FEB PY 1999 VL 84 IS 1-2 BP 183 EP 192 PG 10 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 156TU UT WOS:000078018800020 ER PT J AU Brodley, CE Lane, T Stough, TM AF Brodley, CE Lane, T Stough, TM TI Knowledge discovery and data mining SO AMERICAN SCIENTIST LA English DT Article C1 Purdue Univ, Sch Elect & Comp Engn, W Lafayette, IN 47907 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Brodley, CE (reprint author), Purdue Univ, Sch Elect & Comp Engn, W Lafayette, IN 47907 USA. NR 8 TC 12 Z9 12 U1 0 U2 2 PU SIGMA XI-SCI RES SOC PI RES TRIANGLE PK PA PO BOX 13975, RES TRIANGLE PK, NC 27709 USA SN 0003-0996 J9 AM SCI JI Am. Scientist PD JAN-FEB PY 1999 VL 87 IS 1 BP 54 EP 61 DI 10.1511/1999.16.807 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 146WW UT WOS:000077456500018 ER PT S AU Barth, TJ AF Barth, TJ BE Kroner, D Ohlberger, M Rohde, C TI Numerical methods for gasdynamic systems on unstructured meshes SO AN INTRODUCTION TO RECENT DEVELOPMENTS IN THEORY AND NUMERICS FOR CONSERVATION LAWS SE LECTURE NOTES IN COMPUTATIONAL SCIENCE AND ENGINEERING LA English DT Proceedings Paper CT International-School-on-Theory-and-Numerics-for-Conservation-Laws CY OCT 20-24, 1997 CL UNIV FREIBURG, FREIBURG LITTENWEILER, GERMANY SP Int Sch Theory & Numer Conservat Laws, Univ Freiburg, DFG Gradueirtenkolleg Nichtlineare Differentialgleichungen HO UNIV FREIBURG ID HYPERBOLIC CONSERVATION-LAWS; COMPUTATIONAL FLUID-DYNAMICS; FINITE-ELEMENT FORMULATION; DIFFERENCE APPROXIMATIONS; SCHEMES; EQUATIONS; CONVERGENCE; ENTROPY; SHOCKS; GRIDS AB This article considers stabilized finite element and finite volume discretization techniques for systems of conservation laws. Using newly developed techniques in entropy symmetrization theory, simplified forms of the Galerkin least-squares (GLS) and the discontinuous Galerkin (DG) finite element method are developed ed and analyzed. The use of symmetrization variables yields numerical schemes which inherit global entropy stability properties of the PDE system. Detailed consideration is given to symmetrization of the Euler, Navier-Stokes, and magnetohydrodynamic (MHD) equations. Numerous calculations are presented to evaluate the spatial accuracy and feature resolution capability of the simplified DG and GLS discretizations. Next, upwind finite volume methods are reviewed. Specifically considered are generalizations of Godunov's method to high order accuracy and unstructured meshes. An important component of high order accurate Godunov methods is the spatial reconstruction operator. A number of reconstruction operators are reviewed based on Green-Gauss formulas as well as least-squares approximation. Several theoretical results using maximum principle analysis are presented for the upwind finite volume method. To assess the performance of the upwind finite volume technique, various numerical calculations in computational fluid dynamics are provided. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Barth, TJ (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 55 TC 30 Z9 30 U1 2 U2 4 PU SPRINGER-VERLAG BERLIN PI BERLIN PA HEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANY SN 1439-7358 BN 3-540-65081-4 J9 LECT NOTES COMP SCI PY 1999 VL 5 BP 195 EP 285 PG 91 WC Mathematics, Applied; Mechanics SC Mathematics; Mechanics GA BP35K UT WOS:000084811500005 ER PT B AU Callantine, TJ AF Callantine, TJ BE Nishida, S Inoue, K TI Context in models of human-machine systems SO ANALYSIS, DESIGN AND EVALUATION OF MAN-MACHINE SYSTEMS 1998 LA English DT Proceedings Paper CT 7th IFAC/IFIP/IFORS/IEA Symposium on Analysis, Design and Evaluation of Man-Machine Systems (MMS 98) CY SEP 16-18, 1998 CL KYOTO, JAPAN SP Int Federat Automat Control, Tech Comm Man Machine Syst, Tech Comm Social Impact Automat, Tech Comm Fault Detect Supervision & Safety Tech Proc, Tech Comm Aerosp, Tech Comm Automot Control, Tech Comm Marine Syst, Tech Comm Air Traff Control Automat, Tech Comm Syst, Int Federat Informat Processing, Int Federat Operat Res Soc, Int Ergonom Assoc, Tech Comm Human Interface, Soc Instrument & Control Engineers DE models; modeling; man-machine systems; design; states; events; constraints AB All human-machine systems models represent context. This paper proposes a theory of context through which models may be usefully related and integrated for design. The paper presents examples of context representation in various models, describes an application to developing models for the Crew Activity Tracking System (CATS), and advances context as a foundation for integrated design of complex dynamic systems. Copyright (C) 1998 IFAC. C1 San Jose State Univ, NASA, Ames Res Ctr, San Jose, CA 95192 USA. RP Callantine, TJ (reprint author), San Jose State Univ, NASA, Ames Res Ctr, San Jose, CA 95192 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA SARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS BN 0-08-043032-5 PY 1999 BP 485 EP 490 PG 6 WC Automation & Control Systems; Computer Science, Artificial Intelligence; Computer Science, Cybernetics SC Automation & Control Systems; Computer Science GA BQ60F UT WOS:000088923000081 ER PT S AU Kreutz, KJ Mayewski, PA Twickler, MS Whitlow, SI White, JWC Shuman, CA Raymond, CF Conway, H McConnell, JR AF Kreutz, KJ Mayewski, PA Twickler, MS Whitlow, SI White, JWC Shuman, CA Raymond, CF Conway, H McConnell, JR BE Jacka, TH TI Seasonal variations of glaciochemical, isotopic and stratigraphic properties in Siple Dome (Antarctica) surface snow SO ANNALS OF GLACIOLOGY, VOL 29, 1999 SE ANNALS OF GLACIOLOGY LA English DT Article; Proceedings Paper CT 6th International Symposium on Antarctic Glaciology (ISAG-6) CY SEP 05-09, 1998 CL CHINESE ACAD SCI, LANZHOU INST GLACIOL & GEOCRYOL, LANZHOU, PEOPLES R CHINA SP Int Glaciol Soc, Sci Comm Antarct Res Work Grp Glaciol, Natl Nat Sci Fdn China, State Sci & Technol Commiss China, State Ocean Bureau China, Chinese Acad Sci HO CHINESE ACAD SCI, LANZHOU INST GLACIOL & GEOCRYOL ID GREENLAND ICE CORE; SOUTH-POLE; FIRN; ACCUMULATION; RECORD; TEMPERATURE; CHEMISTRY; CLIMATE; SUMMIT; H2O2 AB Six snow-pit records recovered from Siple Dome, West Antarctica, during 1994 are used to study seasonal variations in chemical (major ion and H2O2), isotopic (deuterium) and physical stratigraphic properties during the 1988-94 period. Comparison of delta D measurements and satellite-derived brightness temperature for the Siple Dome area suggests that most seasonal delta D maxima occur within +/-4 weeks of each 1 January. Several other chemical species (H2O2, non-sea-salt (nss) SO42-, methanesulfonic acid and NO3-) show coeval peaks with delta D, together providing an accurate method for identifying summer accumulation. Sea-salt-derived species generally peak during winter/spring, but episodic input is noted throughout some years. No reliable seasonal signal is identified in species with continental sources (nssCa(2+), nssMg(2+)), NH4+ or nssCl(-). Visible strata such as large depth-hoar layers (>5 cm) are associated with summer accumulation and its metamorphosis, but smaller hear layers and crusts are more difficult to interpret. A multi-parameter approach is found to provide the most accurate dating of these snow-pit records, and is used to determine annual laver thicknesses at each site. Significant spatial accumulation variability exists on an annual basis, but mean accumulation in the sampled 10 km(2) grid for the 1988-94 period is fairly uniform. C1 Univ New Hampshire, Inst Study Earth Oceans & Space, Climate Change Res Ctr, Durham, NH 03824 USA. Univ New Hampshire, Dept Earth Sci, Durham, NH 03824 USA. Univ Colorado, Inst Arctic & Alpine Res, Stable Isotope Lab, Boulder, CO 80303 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Washington, Geophys Program, Seattle, WA 98195 USA. Univ Nevada, Desert Res Inst, Reno, NV 89506 USA. RP Kreutz, KJ (reprint author), Woods Hole Oceanog Inst, Dept Marine Chem & Geochem, Woods Hole, MA 02543 USA. RI White, James/A-7845-2009 OI White, James/0000-0001-6041-4684 NR 52 TC 28 Z9 29 U1 2 U2 3 PU INT GLACIOLOGICAL SOC PI CAMBRIDGE PA LENSFIELD RD, CAMBRIDGE, ENGLAND CB2 1ER SN 0260-3055 BN 0-946417-24-5 J9 ANN GLACIOL PY 1999 VL 29 BP 38 EP 44 DI 10.3189/172756499781821193 PG 7 WC Geochemistry & Geophysics; Geography, Physical SC Geochemistry & Geophysics; Physical Geography GA BP93Z UT WOS:000086691400007 ER PT S AU Yi, DH Bentley, CR AF Yi, DH Bentley, CR BE Jacka, TH TI Geoscience Laser Altimeter System waveform simulation and its applications SO ANNALS OF GLACIOLOGY, VOL 29, 1999 SE ANNALS OF GLACIOLOGY LA English DT Article; Proceedings Paper CT 6th International Symposium on Antarctic Glaciology (ISAG-6) CY SEP 05-09, 1998 CL CHINESE ACAD SCI, LANZHOU INST GLACIOL & GEOCRYOL, LANZHOU, PEOPLES R CHINA SP Int Glaciol Soc, Sci Comm Antarct Res Work Grp Glaciol, Natl Nat Sci Fdn China, State Sci & Technol Commiss China, State Ocean Bureau China, Chinese Acad Sci HO CHINESE ACAD SCI, LANZHOU INST GLACIOL & GEOCRYOL ID GREENLAND; SURFACE AB To study the relationship between surface topography and satellite laser altimetry waveform, a numerical model that simulates an ideal satellite laser altimeter has been developed. It has a Gaussian beam pattern and a Gaussian pulse shape. Different three-dimensional surface topographies have been used in the simulation to generate waveforms. Using a non-linear least-squares method, the generated waveforms were fitted to theoretical models to calculate surface roughness and surface slope. The outputs from the models were then compared with the values calculated from the given assumed surfaces. There is no way to distinguish between a horizontal, randomly rough surface and a smoothly sloping surface from waveform fitting alone. However, if either the surface roughness or the surface slope can be acquired independently, the other one can be determined through waveform fitting. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Ocean & Ice Branch, Greenbelt, MD 20771 USA. Univ Wisconsin, Geophys & Polar Res Ctr, Madison, WI 53706 USA. RP Yi, DH (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Ocean & Ice Branch, Code 971, Greenbelt, MD 20771 USA. NR 21 TC 1 Z9 1 U1 0 U2 5 PU INT GLACIOLOGICAL SOC PI CAMBRIDGE PA LENSFIELD RD, CAMBRIDGE, ENGLAND CB2 1ER SN 0260-3055 BN 0-946417-24-5 J9 ANN GLACIOL PY 1999 VL 29 BP 279 EP 285 PG 7 WC Geochemistry & Geophysics; Geography, Physical SC Geochemistry & Geophysics; Physical Geography GA BP93Z UT WOS:000086691400049 ER PT J AU Bhat, G Cleaveland, R Luttgen, G AF Bhat, G Cleaveland, R Luttgen, G TI A practical approach to implementing real-time semantics SO ANNALS OF SOFTWARE ENGINEERING LA English DT Review ID CONCURRENT SYSTEMS; PROCESS ALGEBRA; VERIFICATION; PRIORITIES; LANGUAGE; CALCULUS; CCS AB This paper investigates implementations of process algebras which are suitable for modeling concurrent real-time systems. It suggests an approach for efficiently implementing real-time semantics using dynamic priorities. For this purpose a process algebra with dynamic priority is defined, whose semantics corresponds one-to-one to traditional real-time semantics. The advantage of the dynamic-priority approach is that it drastically reduces the state-space sizes of the systems in question while preserving all properties of their functional and real-time behavior. The utility of the technique is demonstrated by a case study that deals with the formal modeling and verification of several aspects of the widely-used SCSI-2 bus-protocol. The case study is carried out in the Concurrency Workbench of North Carolina, an automated verification tool in which the process algebra with dynamic priority is implemented. It turns out that the state space of the bus-protocol model is about an order of magnitude smaller than the one resulting from real-time semantics. The accuracy of the model is proved by applying model checking for verifying several mandatory properties of the bus protocol. C1 MakeLabs, Cary, NC 27511 USA. SUNY Stony Brook, Dept Comp Sci, Stony Brook, NY 11794 USA. NASA, Inst Comp Applicat Sci & Engn, Langley Res Ctr, Hampton, VA 23681 USA. RP Bhat, G (reprint author), MakeLabs, 4000 Regency Pkwy,Suite 150, Cary, NC 27511 USA. EM luettgen@icase.edu NR 27 TC 5 Z9 5 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 1022-7091 J9 ANN SOFTW ENG JI Ann. Softw. Eng. PY 1999 VL 7 BP 127 EP 155 DI 10.1023/A:1018982020561 PG 29 WC Computer Science, Software Engineering SC Computer Science GA 245LC UT WOS:000083109200007 ER PT B AU Barrett, P Singh, KP Mitchell, S AF Barrett, P Singh, KP Mitchell, S BE Hellier, C Mukai, K TI The soft X-ray luminosity function of polars SO ANNAPOLIS WORKSHOP ON MAGNETIC CATACLYSMIC VARIABLES SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Annapolis Workshop on Magnetic Cataclysmic Variables CY JUL 13-17, 1998 CL ANNAPOLIS, MD ID GLOBULAR-CLUSTERS; CATACLYSMIC VARIABLES; PULSARS; ROSAT AB The soft X-ray luminosity function of polars is determined from a sample of 37 ROSAT PSPC spectra. We find qualitative agreement with a previous study of the soft X-ray luminosity function using EXOSAT data, but disagree with it quantitatively because of our larger sample and better data. We find the average soft X-ray luminosity to be 3 x 10(31) ergs s(-1), or about an order of magnitude less than the EXOSAT value. We discuss the implications of this result with respect to X-ray processes, the evolution of magnetic cataclysmic variables, and the dynamics of globular clusters. C1 NASA, GSFC, High Energy Astrophys Lab, Huntsville, AL 35812 USA. RP Barrett, P (reprint author), NASA, GSFC, High Energy Astrophys Lab, Huntsville, AL 35812 USA. NR 17 TC 7 Z9 7 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-77-5 J9 ASTR SOC P PY 1999 VL 157 BP 180 EP 186 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BM90T UT WOS:000080088400029 ER PT S AU Ford, CN AF Ford, CN GP IEEE TI Effective time on station (ETOS): A new operational mission reliability parameter SO ANNUAL RELIABILITY AND MAINTAINABILITY SYMPOSIUM, 1999 PROCEEDINGS SE PROCEEDINGS : ANNUAL RELIABILITY AND MAINTAINABILITY SYMPOSIUM LA English DT Article; Proceedings Paper CT International Symposium on Product Quality and Integrity - Managing Uncertainty CY JAN 18-21, 1999 CL WASHINGTON, D.C. SP IEEE Reliabil Soc, Amer Inst Aeronaut & Astronaut, Inst Environm Sci & Technol, Soc Automot Engineers Inc, Soc Reliabil Engineers, Amer Soc Qual Electr Div, Inst Ind Engineers, Soc Logist Engineers, Syst Safety Soc, Amer Soc Qual Reliabil Div DE effectiveness; mission reliability; operational reliability; operational availability AB Effective Time On Station (ETOS) is a new reliability parameter used for systems that are designed to provided coverage (surveillance, defense, etc) far a specified amount of time. The ETOS parameter can be used on systems that provide some type of coverage versus systems that have events defining their completion of a mission. ETOS measures the ability of a system to remain operational for the scheduled on-station time. C1 NASA, FDC NYMA Inc, Langley Res Ctr, Hampton, VA 23681 USA. RP Ford, CN (reprint author), NASA, FDC NYMA Inc, Langley Res Ctr, Mail Stop 248, Hampton, VA 23681 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU I E E E PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 0149-144X BN 0-7803-5143-6 J9 P A REL MAI PY 1999 BP 118 EP 121 DI 10.1109/RAMS.1999.744106 PG 4 WC Engineering, Multidisciplinary SC Engineering GA BM43V UT WOS:000078742800020 ER PT J AU Des Marais, DJ Walter, MR AF Des Marais, DJ Walter, MR TI Astrobiology: Exploring the origins, evolution, and distribution of life in the Universe SO ANNUAL REVIEW OF ECOLOGY AND SYSTEMATICS LA English DT Review DE microorganisms; Precambrian; biospheres; solar system; planets; origin of life ID MARTIAN METEORITE ALH84001; HYDROTHERMAL SYSTEMS; PLANETARY COMPANION; HABITABLE ZONES; EARLY EARTH; PAST LIFE; MARS; SEARCH; ALLAN-HILLS-84001; ATMOSPHERE AB The search for the origins of life and its presence beyond Earth is strengthened by new technology and by evidence that life tolerates extreme conditions and that planets are widespread. Astrobiologists learn how planets develop and maintain habitable conditions. They combine biological and information sciences to decipher the origins of life. They examine how biota, particularly microorganisms, evolve, at scales from the molecular to the biosphere level, including interactions with long-term planetary changes. Astrobiologists learn how to recognize the morphological, chemical, and spectroscopic signatures of life in order to explore both extraterrestrial samples and electromagnetic spectra reflected from extrasolar planets. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Macquarie Univ, Sch Earth Sci, N Ryde, NSW 2109, Australia. RP Des Marais, DJ (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 102 TC 41 Z9 45 U1 7 U2 34 PU ANNUAL REVIEWS INC PI PALO ALTO PA 4139 EL CAMINO WAY, PO BOX 10139, PALO ALTO, CA 94303-0139 USA SN 0066-4162 J9 ANNU REV ECOL SYST JI Annu. Rev. Ecol. Syst. PY 1999 VL 30 BP 397 EP 420 PG 24 WC Ecology; Evolutionary Biology SC Environmental Sciences & Ecology; Evolutionary Biology GA 276MX UT WOS:000084882700014 PM 11543275 ER PT J AU Turkel, E AF Turkel, E TI Preconditioning techniques in computational fluid dynamics SO ANNUAL REVIEW OF FLUID MECHANICS LA English DT Review DE computational fluid; aerodynamic; Navier-Stokes; convergence; acceleration ID EQUATIONS; FLOWS AB An overview of preconditioning for the steady-state compressible inviscid fluid dynamic equations is presented. Extensions to the Navier-Stokes equations are also considered. These preconditioners are necessary for many algorithms in order to have the correct behavior at low speeds and to converge to the solution of the incompressible equations as the Mach number goes to zero. In addition, the preconditioning accelerates the convergence to a steady state for problems in which a significant portion of the flow is low speed. This low speed preconditioner can be combined with Jacobi and line preconditioners to damp high frequencies at all speeds. This is necessary for use with multigrid methods. Such combined methods are also better at accelerating problems with high aspect ratios. Details of the implementation are presented including several different variants for the preconditioning matrix. C1 Tel Aviv Univ, Sackler Fac Exact Sci, Sch Math Sci, IL-69978 Tel Aviv, Israel. NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP Turkel, E (reprint author), Tel Aviv Univ, Sackler Fac Exact Sci, Sch Math Sci, IL-69978 Tel Aviv, Israel. EM turkel@math.tau.ac.il RI Turkel, Eli/F-6297-2011 OI Turkel, Eli/0000-0003-4273-0303 NR 39 TC 163 Z9 187 U1 2 U2 22 PU ANNUAL REVIEWS INC PI PALO ALTO PA 4139 EL CAMINO WAY, PO BOX 10139, PALO ALTO, CA 94303-0139 USA SN 0066-4189 J9 ANNU REV FLUID MECH JI Annu. Rev. Fluid Mech. PY 1999 VL 31 BP 385 EP 416 DI 10.1146/annurev.fluid.31.1.385 PG 32 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 164KJ UT WOS:000078462900011 ER PT J AU Huang, NE Shen, Z Long, SR AF Huang, NE Shen, Z Long, SR TI A new view of nonlinear water waves: The Hilbert spectrum SO ANNUAL REVIEW OF FLUID MECHANICS LA English DT Review DE Hilbert transform; Hilbert spectral analysis; empirical mode decomposition; nonlinear process; nonstationary ID FREQUENCY SIGNAL ANALYSIS; LINEAR SCHRODINGER-EQUATION; FULLY-DEVELOPED TURBULENCE; GENERATED GRAVITY-WAVES; DEEP-WATER; WIGNER DISTRIBUTION; WIND-WAVES; EQUILIBRIUM SPECTRA; ENERGY-DISSIPATION; SURFACE-WAVES AB We survey the newly developed Hilbert spectral analysis method and its applications to Stokes waves, nonlinear wave evolution processes, the spectral form of the random wave field, and turbulence. Our emphasis is on the inadequacy of presently available methods in nonlinear and nonstationary data analysis. Hilbert spectral analysis is here proposed as an alternative. This new method provides not only a more precise definition of particular events in time-frequency space than wavelet analysis, but also more physically meaningful interpretations of the underlying dynamic processes. C1 CALTECH, Div Engn Sci, Pasadena, CA 91125 USA. Univ Calif Irvine, Dept Civil Engn, Irvine, CA 92697 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Observat Sci Branch,Wallops Flight Facil, Wallops Isl, VA 23337 USA. RP Huang, NE (reprint author), CALTECH, Div Engn Sci, Pasadena, CA 91125 USA. EM long@osb.wff.nasa.gov RI Long, Steven/D-7248-2012 NR 92 TC 973 Z9 1406 U1 13 U2 105 PU ANNUAL REVIEWS PI PALO ALTO PA 4139 EL CAMINO WAY, PO BOX 10139, PALO ALTO, CA 94303-0139 USA SN 0066-4189 J9 ANNU REV FLUID MECH JI Annu. Rev. Fluid Mech. PY 1999 VL 31 BP 417 EP 457 DI 10.1146/annurev.fluid.31.1.417 PG 51 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 164KJ UT WOS:000078462900012 ER PT J AU Gnoffo, PA AF Gnoffo, PA TI Planetary-entry gas dynamics SO ANNUAL REVIEW OF FLUID MECHANICS LA English DT Review DE hypersonic; thermochemical nonequilibrium; Mars Pathfinder; Galileo; Stardust; Mars Global Surveyor ID ULTRAVIOLET ROCKET EXPERIMENTS; CHEMICAL-KINETIC PROBLEMS; FUTURE NASA MISSIONS; MARS ENTRIES; NONEQUILIBRIUM; MODEL; EARTH AB A review of planetary-entry gas dynamics is presented. Evolution of a blunt-body flowfield from a free molecular flow environment to a continuum environment is described. Simulations of near-wake flow phenomena, important for defining aerobrake payload environments, are also discussed. Some topics to be highlighted include aerodynamic coefficient predictions with emphasis on high-temperature gas effects; surface heating and temperature predictions for thermal protection system (TPS) design in a high-temperature, thermochemical nonequilibrium environment; and thermochemical models required for numerical flow simulation. Recent applications involving atmospheric entry into Jupiter (Galileo), Mars (Pathfinder and Global Surveyor), and a planned mission in which dust from the tail of a comet will be returned to Earth (Stardust) will provide context for this discussion. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Gnoffo, PA (reprint author), NASA, Langley Res Ctr, MS 408A, Hampton, VA 23681 USA. EM p.a.gnoffo@larc.nasa.gov NR 103 TC 54 Z9 54 U1 1 U2 9 PU ANNUAL REVIEWS INC PI PALO ALTO PA 4139 EL CAMINO WAY, PO BOX 10139, PALO ALTO, CA 94303-0139 USA SN 0066-4189 J9 ANNU REV FLUID MECH JI Annu. Rev. Fluid Mech. PY 1999 VL 31 BP 459 EP 494 DI 10.1146/annurev.fluid.31.1.459 PG 36 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 164KJ UT WOS:000078462900013 ER PT B AU Nicholson, LM Hinkley, JA Whitley, KS Gates, TS AF Nicholson, LM Hinkley, JA Whitley, KS Gates, TS GP SOC PLAST ENGINEERS SOC PLAST ENGINEERS SOC PLAST ENGINEERS TI Effects of molecular structure on macroscopic mechanical properties of an advanced polymer (LARC (TM)-SI) SO ANTEC '99: PLASTICS BRIDGING THE MILLENNIA, CONFERENCE PROCEEDINGS, VOLS I-III: VOL I: PROCESSING; VOL II: MATERIALS; VOL III: SPECIAL AREAS; LA English DT Proceedings Paper CT 57th Annual Technical Conference of the SPE on Plastics Bridging the Millennia (ANTEC 99) CY MAY 02-06, 1999 CL NEW YORK, NY SP Soc Plast Engineers DE molecular weight; elastic properties; Tg; advanced polymer ID POLYIMIDE AB Mechanical testing of an advanced polymer resin with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The elastic properties, inelastic elongation behavior, and notched tensile strength all as a function of molecular weight and test temperature were determined. It was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Nicholson, LM (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU SOC PLASTICS ENGINEERS PI BROOKFIELD CENTER PA 14 FAIRFIELD DR, BROOKFIELD CENTER, CT 06805 USA BN 1-56676-804-7 PY 1999 BP 1875 EP 1879 PG 5 WC Engineering, Chemical; Materials Science, Multidisciplinary; Materials Science, Composites; Polymer Science SC Engineering; Materials Science; Polymer Science GA BN12H UT WOS:000080784900354 ER PT B AU Said, MA AF Said, MA GP SOC PLAST ENGINEERS SOC PLAST ENGINEERS SOC PLAST ENGINEERS TI Mechanical behavior of fabric-film laminates SO ANTEC '99: PLASTICS BRIDGING THE MILLENNIA, CONFERENCE PROCEEDINGS, VOLS I-III: VOL I: PROCESSING; VOL II: MATERIALS; VOL III: SPECIAL AREAS; LA English DT Proceedings Paper CT 57th Annual Technical Conference of the SPE on Plastics Bridging the Millennia (ANTEC 99) CY MAY 02-06, 1999 CL NEW YORK, NY SP Soc Plast Engineers C1 NASA, Goddard Space Flight Ctr, Wallops Island, VA 23337 USA. RP Said, MA (reprint author), NASA, Goddard Space Flight Ctr, Wallops Island, VA 23337 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU SOC PLASTICS ENGINEERS PI BROOKFIELD CENTER PA 14 FAIRFIELD DR, BROOKFIELD CENTER, CT 06805 USA BN 1-56676-804-7 PY 1999 BP 2570 EP 2572 PG 3 WC Engineering, Chemical; Materials Science, Multidisciplinary; Materials Science, Composites; Polymer Science SC Engineering; Materials Science; Polymer Science GA BN12H UT WOS:000080784900486 ER PT S AU Chutjian, A Greenwood, JB Smith, SJ AF Chutjian, A Greenwood, JB Smith, SJ BE Duggan, JL Morgan, IL TI Electron-ion collision studies using a 14.0 GHz ECRIS SO APPLICATION OF ACCELERATORS IN RESEARCH AND INDUSTRY, PTS 1 AND 2 SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 15th International Conference on the Application of Accelerators in Research and Industry CY NOV 04-07, 1998 CL UNIV N TEXAS, DENTON, TX SP US DOE, Natl Sci Fdn, Univ N Texas HO UNIV N TEXAS ID EXCITATION CROSS-SECTIONS; ENERGY-LOSS; RESONANCE TRANSITIONS; ELASTIC-SCATTERING; IMPACT EXCITATION; PLASMA TORUS AB A new 14.0 GHz electron-cyclotron resonance ion source, the so-called Caprice source, has been in operation at JPL/Caltech for over a year. The source produces ample currents of multiply-charged ions (MCIs) for atomic-physics measurements, in particular of MCIs that are of astrophysical interest. Studies at JPL are carried out using Caprice and a three-way beam switcher allowing one to make measurements of absolute electron-ion excitation cross sections using electron energy loss and merged or crossed beams, f-values of metastable states using a Kingdon ion trap, and absolute ion-neutral charge exchange cross sections, with X-ray detection, in a beam line presently being tested. C1 CALTECH, Jet Prop Lab, Atom & Mol Collis Team, Pasadena, CA 91109 USA. RP Chutjian, A (reprint author), CALTECH, Jet Prop Lab, Atom & Mol Collis Team, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Greenwood, Jason/L-4799-2014 NR 28 TC 17 Z9 17 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 1-56396-825-8 J9 AIP CONF PROC PY 1999 VL 475 BP 881 EP 886 PG 4 WC Chemistry, Physical; Materials Science, Characterization & Testing; Physics, Atomic, Molecular & Chemical; Physics, Nuclear; Physics, Particles & Fields; Spectroscopy SC Chemistry; Materials Science; Physics; Spectroscopy GA BN31G UT WOS:000081503200210 ER PT S AU Jost, H Loewenstein, M AF Jost, H Loewenstein, M BE Fried, A TI Argus: A lightweight TDL instrument to measure stratospheric tracers SO APPLICATION OF TUNABLE DIODE AND OTHER INFRARED SOURCES FOR ATMOSPHERIC STUDIES AND INDUSTRIAL PROCESSING MONITORING II SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Application of Tunable Diode and Other Infrared Sources for Atmospheric Studies and Industrial Processing Monitoring II CY JUL 19-20, 1999 CL DENVER, CO SP SPIE DE atmospheric tracers; second harmonic detection; stratosphere; methane; nitrous oxide AB Argus is a two channel, tunable diode laser instrument which measures atmospheric methane and nitrous oxide in the upper troposphere and stratosphere up to an altitude of 32 Ban using second harmonic detection. Investigations of stratospheric transport from mid-latitudes into the tropics is the current focus of our work which requires high precision and high accuracy data. Argus was designed for use on remotely piloted aircraft or light-payload balloons and weighs less than 20 kg. The two channels each have their own laser, optics, detector and signal processing chains. We sample methane at 3.3 mu m and nitrous oxide at 4.5 mu m at a rate of 0.1 Hz. The gas is sampled in a Herriott cell which has a total path length of 18.8 m. Each laser is current- and temperature-controlled by a dedicated microprocessor. We sweep the laser at 10 Hz and record direct absorption spectra during the ramping of the laser current. The lasers are modulated with a 40 kHz sine wave; a phase sensitive amplifier and integrator detects the second harmonic data. The analysis is performed offline by applying direct fits to the measured spectra using the non-linear Marquardt-Levenberg algorithm. We have recently flown Argus and ATLAS together on the ER-2 platform for comparison. Precision of Argus is 0.6% and accuracy is estimated to 4-17% increasing with altitude. C1 NASA, Ames Res Ctr, Atmospher Chem & Dynam Branch, Moffett Field, CA 94035 USA. RP Jost, H (reprint author), NASA, Ames Res Ctr, Atmospher Chem & Dynam Branch, MS 245-5, Moffett Field, CA 94035 USA. NR 8 TC 2 Z9 2 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3244-X J9 P SOC PHOTO-OPT INS PY 1999 VL 3758 BP 123 EP 130 DI 10.1117/12.366444 PG 8 WC Environmental Sciences; Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing; Optics SC Environmental Sciences & Ecology; Instruments & Instrumentation; Meteorology & Atmospheric Sciences; Remote Sensing; Optics GA BP12C UT WOS:000084180300014 ER PT S AU Kiang, RK AF Kiang, RK BE Priddy, KL Keller, PE Fogel, DB Bezdek, JC TI Textural-contextual labeling and metadata generation for remote sensing applications SO APPLICATIONS AND SCIENCE OF COMPUTATIONAL INTELLIGENCE II SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Applications and Science of Computational Intelligence II CY APR 05-08, 1999 CL ORLANDO, FL SP SPIE - Int Soc Opt Engn DE neural network; remote sensing; textural; contextual; metadata ID RANDOM-FIELDS; CLASSIFICATION; IMAGES; PERCEPTION; FEATURES AB Despite the extensive research and the advent of several new information technologies in the last three decades, machine labeling of ground categories using remotely sensed data has not become a routine process. Considerable amount of human intervention is needed to achieve a level of acceptable labeling accuracy. A number of fundamental reasons may explain why machine labeling has not become automatic. In addition, there may be shortcomings in the methodology for labeling ground categories. The spatial information of a pixel, whether textural or contextual, relates a pixel to its surroundings. This information should be utilized to improve the performance of machine labeling of ground categories. Landsat-4 Thematic Mapper (TM) data taken in July 1982 over an area in the vicinity of Washington, D.C. are used in this study. On-line texture extraction by neural networks may not be the most efficient way to incorporate textural information into the labeling process. Texture features are pre-computed from cooccurrence matrices and then combined with a pixel's spectral and contextual information as the input to a neural network. The improvement in labeling accuracy with spatial information included is significant. The prospect of automatic generation of metadata consisting of ground categories, textural and contextual information is discussed. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kiang, RK (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 21 TC 1 Z9 1 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3196-6 J9 P SOC PHOTO-OPT INS PY 1999 VL 3722 BP 243 EP 248 DI 10.1117/12.342879 PG 6 WC Computer Science, Artificial Intelligence; Computer Science, Interdisciplinary Applications; Computer Science, Theory & Methods; Engineering, Electrical & Electronic; Optics SC Computer Science; Engineering; Optics GA BM94R UT WOS:000080213000022 ER PT S AU Castano, R Mann, T Mjolsness, E AF Castano, R Mann, T Mjolsness, E BE Tescher, AG TI Texture analysis for Mars rover images SO APPLICATIONS OF DIGITAL IMAGE PROCESSING XXII SE Proceedings of SPIE LA English DT Proceedings Paper CT Conference on Applications of Digital Image Processing XXII CY JUL 20-23, 1999 CL DENVER, CO SP SPIE DE texture analysis; Gabor filters ID LOCALIZED SPATIAL FILTERS; SEGMENTATION AB The problem addressed in this paper is that of clustering image pixels into regions of homogenous geological texture. Future revers on Mars will need to be able to intelligently select data collection targets. One goal of intelligent data selection for maximizing scientific return is to sample all distinct types of rocks that may be encountered. Different rock types often have a characteristic visual texture, thus visual texture is a rich source of information for separating rocks into different types. Recent work on using texture to segment images has been very successful on images with homogenous textures such as mosaics of Brodatz textures and some natural scenes. The geologic history of a rock leads to irregular shapes and surface textures. As a result, the textures in our images are not as homogeneous as those in Brodatz mosaics. Our approach is to extract textural information by applying a bank of Gabor filters to the image. The resulting texture vectors are then clustered. Banks of filters constrain the relationships of the filter parameters both within a single filter and between filters. Often researchers have used parameter values that are thought to correspond to the human visual system, however the effects of adjusting these parameters have not been thoroughly studied. We systematically explore tradeoffs in the parameter space of the filter bank and quantify the effects of the tradoffs on the quality of the resulting clusters. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Castano, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Rebecca.Castano@jpl.nasa.gov; Tobias.Mann@jpl.nasa.gov; Eric.Mjolsness@jpl.nasa.gov NR 12 TC 2 Z9 2 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3294-6 J9 PROC SPIE PY 1999 VL 3808 BP 162 EP 173 DI 10.1117/12.365832 PG 12 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Computer Science, Theory & Methods; Engineering, Electrical & Electronic; Optics SC Computer Science; Engineering; Optics GA BN98Z UT WOS:000083768500016 ER PT J AU Honecy, FS Bozzolo, G Good, B AF Honecy, FS Bozzolo, G Good, B TI Surface segregation in ternary alloys: a BFS study of Ni-Al-Cu(100) surface composition SO APPLIED SURFACE SCIENCE LA English DT Article DE segregation; alloy segregation; semiempirical methods; Ni-Al-Cu; atomistic simulations; surface composition; Monte Carlo; BFS method AB Atomistic simulations of surface segregation constitute an essential tool in determining the surface composition and structure of binary or higher order alloys. The presence of metastable stares, where widely different surface composition profiles are energetically possible, are severe tests for the ability of experimental techniques for accurately determining the composition of the surface. A clear example of such phenomenon is analyzed in this paper, where the Bozzolo-Fenante-Smith (BFS) semiempirical method for alloys is applied to the study of surface composition of Ni-rich Ni-Al-Cu alloys. A wide range of Cu concentration is considered, showing distinct segregation trends characterizing the low-Cu and high-Cu concentration regimes. The existence of metastable states with energy close to that of the ground state is identified and shown to drive the resulting segregation pattern. The results of several Monte Carlo/Metropolis simulations are shown, highlighting the role of the initial state used in the simulation and the temperature treatment of the sample. (C) 1999 Elsevier Science B.V. All rights reserved. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. RP Bozzolo, G (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. EM guillermo.bozzolo@lerc.nasa.gov NR 10 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-4332 EI 1873-5584 J9 APPL SURF SCI JI Appl. Surf. Sci. PD JAN PY 1999 VL 137 IS 1-4 BP 157 EP 162 DI 10.1016/S0169-4332(98)00474-7 PG 6 WC Chemistry, Physical; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Chemistry; Materials Science; Physics GA 155BB UT WOS:000077925100021 ER PT B AU Bar-Cohen, Y AF Bar-Cohen, Y GP ASNT ASNT TI Bookmarklng the NDE capability and challenges near the dawn of the new millennium SO ASNT FALL CONFERENCE AND QUALITY TESTING SHOW PAPER SUMMARIES LA English DT Proceedings Paper CT American-Society-for-Nondestructive-Testing Fall Conference and Quality Testing Show CY OCT 11-15, 1999 CL PHOENIX, AZ SP Amer Soc Nondestruct Testing C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bar-Cohen, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,82-105, Pasadena, CA 91109 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC NONDESTRUCTIVE TESTING PI COLUMBUS PA 1711 ARLINGATE LANE, PO BOX 28518, COLUMBUS, OH 43228-0518 USA BN 1-57117-036-7 PY 1999 BP 49 EP 53 PG 5 WC Instruments & Instrumentation; Materials Science, Characterization & Testing SC Instruments & Instrumentation; Materials Science GA BU34D UT WOS:000175724600008 ER PT B AU Mih, DT AF Mih, DT GP ASNT ASNT TI NDE of microelectronics by real time x-ray imaging SO ASNT FALL CONFERENCE AND QUALITY TESTING SHOW PAPER SUMMARIES LA English DT Proceedings Paper CT American-Society-for-Nondestructive-Testing Fall Conference and Quality Testing Show CY OCT 11-15, 1999 CL PHOENIX, AZ SP Amer Soc Nondestruct Testing C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Mih, DT (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER SOC NONDESTRUCTIVE TESTING PI COLUMBUS PA 1711 ARLINGATE LANE, PO BOX 28518, COLUMBUS, OH 43228-0518 USA BN 1-57117-036-7 PY 1999 BP 57 EP 57 PG 1 WC Instruments & Instrumentation; Materials Science, Characterization & Testing SC Instruments & Instrumentation; Materials Science GA BU34D UT WOS:000175724600010 ER PT B AU Ames, TJ Sall, KB Warsaw, CE AF Ames, TJ Sall, KB Warsaw, CE BE Mehringer, DM Plante, RL Roberts, DA TI NASA's instrument control markup language (ICML) SO ASTRONOMICAL DATA ANALYSIS SOFTWARE AND SYSTEMS VIII SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 8th Annual Conference for Astronomical Data Analysis Software and Systems (ADASS 98) CY NOV 01-04, 1998 CL UNIV ILLINOIS URBANA-CHAMPAIGN, URBANA, IL SP Natl Ctr Supercomp Applicat, Univ Illinois Astron Dept, Smithsonian Astrophys Observ, Natl Radio Astron Observ, Natl Opt Astron Observ, Space Telescope European Coodinating Facility, Sun Microsyst, Res Syst Inc, NASA, Natl Sci Fdn HO UNIV ILLINOIS URBANA-CHAMPAIGN AB This paper describes our experience in using XML to aid in collaborative scientific research involving infrared astronomy. We describe our current efforts for SOFIA in developing an XML vocabulary for instrument description, communication and control, pipeline algorithms, metadata, and documentation. Out focus has been infrared astronomy, although most of the techniques employed have much wider applicability. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ames, TJ (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-94-5 J9 ASTR SOC P PY 1999 VL 172 BP 103 EP 106 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN88T UT WOS:000083347000022 ER PT B AU Cheung, CY Roussopoulos, N Kelley, S Blackwell, J AF Cheung, CY Roussopoulos, N Kelley, S Blackwell, J BE Mehringer, DM Plante, RL Roberts, DA TI A search and discovery tool - AMASE SO ASTRONOMICAL DATA ANALYSIS SOFTWARE AND SYSTEMS VIII SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 8th Annual Conference for Astronomical Data Analysis Software and Systems (ADASS 98) CY NOV 01-04, 1998 CL UNIV ILLINOIS URBANA-CHAMPAIGN, URBANA, IL SP Natl Ctr Supercomp Applicat, Univ Illinois Astron Dept, Smithsonian Astrophys Observ, Natl Radio Astron Observ, Natl Opt Astron Observ, Space Telescope European Coodinating Facility, Sun Microsyst, Res Syst Inc, NASA, Natl Sci Fdn HO UNIV ILLINOIS URBANA-CHAMPAIGN AB The Astrophysics Multispectral Archive Search Engine (AMASE) is a metadatabase prototype built using object-oriented database methodology which allows mission data to be searched easily using scientific parameters. We discuss the implementation issues that arise in integrating heterogeneous data sources, the form and contents of metadata, the creation of cross-system object identifiers, specific tools to handle bulk loading and incremental data loading, interoperability with relational databases, and our future work to extend the capabilities of AMASE. C1 NASA, Goddard Space Flight Ctr, Astrophys Data Facil, Greenbelt, MD 20771 USA. RP Cheung, CY (reprint author), NASA, Goddard Space Flight Ctr, Astrophys Data Facil, Greenbelt, MD 20771 USA. NR 5 TC 2 Z9 2 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-94-5 J9 ASTR SOC P PY 1999 VL 172 BP 213 EP 216 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN88T UT WOS:000083347000048 ER PT B AU Kargatis, VE Shaya, EJ Blackwell, JH Borne, KD White, RA Cheung, CY AF Kargatis, VE Shaya, EJ Blackwell, JH Borne, KD White, RA Cheung, CY BE Mehringer, DM Plante, RL Roberts, DA TI Web-based tools for exploration of ADC data holdings and NASA data archives SO ASTRONOMICAL DATA ANALYSIS SOFTWARE AND SYSTEMS VIII SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 8th Annual Conference for Astronomical Data Analysis Software and Systems (ADASS 98) CY NOV 01-04, 1998 CL UNIV ILLINOIS URBANA-CHAMPAIGN, URBANA, IL SP Natl Ctr Supercomp Applicat, Univ Illinois Astron Dept, Smithsonian Astrophys Observ, Natl Radio Astron Observ, Natl Opt Astron Observ, Space Telescope European Coodinating Facility, Sun Microsyst, Res Syst Inc, NASA, Natl Sci Fdn HO UNIV ILLINOIS URBANA-CHAMPAIGN AB The NASA Astrophysics Data Facility has developed several new tools to facilitate the browsing and visualization of astronomical catalog and journal table data at the Astronomical Data Center (ADC), and to find associated observational data at various data archives. The ADC Viewer allows users to select, cull, and manipulate ADC catalogs and journal tables, and display them in a plotting tool called Catseye. IMPReSS is a tool that displays aperture silhouettes within a specified sky region of a variety of space-based missions, and then links directly to the archived data held at external sites. All three tools are interoperable with other astronomical resources. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Kargatis, VE (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-94-5 J9 ASTR SOC P PY 1999 VL 172 BP 217 EP 220 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN88T UT WOS:000083347000049 ER PT B AU Heikkila, CW McGlynn, TA White, NE AF Heikkila, CW McGlynn, TA White, NE BE Mehringer, DM Plante, RL Roberts, DA TI Astrobrowse: a web agent for querying astronomical databases SO ASTRONOMICAL DATA ANALYSIS SOFTWARE AND SYSTEMS VIII SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 8th Annual Conference for Astronomical Data Analysis Software and Systems (ADASS 98) CY NOV 01-04, 1998 CL UNIV ILLINOIS URBANA-CHAMPAIGN, URBANA, IL SP Natl Ctr Supercomp Applicat, Univ Illinois Astron Dept, Smithsonian Astrophys Observ, Natl Radio Astron Observ, Natl Opt Astron Observ, Space Telescope European Coodinating Facility, Sun Microsyst, Res Syst Inc, NASA, Natl Sci Fdn HO UNIV ILLINOIS URBANA-CHAMPAIGN AB Astrobrowse is a user agent which significantly streamlines the process of gathering astronomical data on the web. With it, a user can query thousands of resources without having to search through old bookmark lists, deal with out-of-date URLs, or spend time figuring out how to use each resource's unique input form. Given a user's selection of web-based astronomical databases and an object name or coordinates, Astrobrowse will explode queries to all selected databases and collect the results. Since the introduction of the prototype at ADASS VII (McGlynn & White 1998), many changes have been made to the service, from adding JavaScript form validation, to the adoption of GLU (Fernique, Ochsenbein & Wenger 1998) as the mechanism for keeping the resource URLs current. This software is freely available to anyone wishing to become an Astrobrowse node. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Heikkila, CW (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 2 TC 18 Z9 18 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-94-5 J9 ASTR SOC P PY 1999 VL 172 BP 221 EP 224 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN88T UT WOS:000083347000050 ER PT B AU Pence, W AF Pence, W BE Mehringer, DM Plante, RL Roberts, DA TI CFITSIO, v2.0: A new full-featured data interface SO ASTRONOMICAL DATA ANALYSIS SOFTWARE AND SYSTEMS VIII SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 8th Annual Conference for Astronomical Data Analysis Software and Systems (ADASS 98) CY NOV 01-04, 1998 CL UNIV ILLINOIS URBANA-CHAMPAIGN, URBANA, IL SP Natl Ctr Supercomp Applicat, Univ Illinois Astron Dept, Smithsonian Astrophys Observ, Natl Radio Astron Observ, Natl Opt Astron Observ, Space Telescope European Coodinating Facility, Sun Microsyst, Res Syst Inc, NASA, Natl Sci Fdn HO UNIV ILLINOIS URBANA-CHAMPAIGN AB Version 2.0 of the CFITSIO subroutine interface for reading and writing FITS format data files is now available from the HEASARC web site. Some of the major new features in this version are the ability to read FITS files over the network, support for reading IRAF format images, and options for filtering the input file at run time. C1 NASA, Goddard Space Flight Ctr, HEASARC, Greenbelt, MD 20771 USA. RP Pence, W (reprint author), NASA, Goddard Space Flight Ctr, HEASARC, Greenbelt, MD 20771 USA. NR 0 TC 58 Z9 58 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-94-5 J9 ASTR SOC P PY 1999 VL 172 BP 487 EP 489 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN88T UT WOS:000083347000109 ER PT J AU Walborn, NR Barba, RH Brandner, W Rubio, M Grebel, EK Probst, RG AF Walborn, NR Barba, RH Brandner, W Rubio, M Grebel, EK Probst, RG TI Some characteristics of current star formation in the 30 Doradus Nebula revealed by HST/NICMOS SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : starburst; H II regions; infrared radiation; ISM : individual (30 Doradus); ISM : molecules; Magellanic Clouds; stars : formation ID LARGE MAGELLANIC CLOUD; SPACE-TELESCOPE IMAGES; 30-DORADUS; N-11; REGION; TABLES AB The extensive "second generation" of star formation within the 30 Doradus Nebula, evidently triggered by the R136 central cluster around its periphery, has been imaged with the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope. Many new IR sources, including multiple systems, clusters, and nebular structures, are found in these images. Six of the NICMOS fields are described here, in comparison with the WFPC2 images of the same fields. Knots 1-3 of Walborn & Blades (early O stars embedded in dense nebular knots) are all found to be compact multiple systems. Knot 1 is shown to reside at the top of a massive dust pillar oriented directly toward R136, whose summit has just been removed, exposing the newborn stellar system. Knots 1 and 3 are also near the brightest IR sources in the region, while parsec-scale jet structures are discovered in association with Knots 2 and 3. The Knot 2 structures consist of detached, nonstellar IR sources aligned on either side of the stellar system, which are interpreted as impact points of a highly collimated, possibly rotating bipolar jet on the surrounding dark clouds; the H2O maser found by Whiteoak et al. is also in this field. These outflows from young massive stars in 30 Dor are the first extragalactic examples of the phenomenon. In the field of the pillars south of R136, recently discussed in comparison with the M16 pillars by Scowen et al., a new luminous stellar IR source has been discovered. These results establish the 30 Doradus Nebula as a prime region in which to investigate the formation and very early evolution of massive stars and multiple systems. The theme of triggered formation within the heads of extensive dust pillars oriented toward R136 is strong. In addition, these results provide further insights into the global structure and evolution of 30 Doradus, which are significant in view of its status as the best resolved extragalactic starburst. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Univ Chile, Dept Astron, Santiago, Chile. Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95064 USA. Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, La Serena, Chile. RP Walborn, NR (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. RI Barba, Rodolfo/P-4649-2014; Rubio, Monica/J-3384-2016 OI Barba, Rodolfo/0000-0003-1086-1579; NR 27 TC 81 Z9 81 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD JAN PY 1999 VL 117 IS 1 BP 225 EP 237 DI 10.1086/300711 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 158GU UT WOS:000078108300023 ER PT J AU Piotto, G Zoccali, M King, IR Djorgovski, SG Sosin, C Dorman, B Rich, RM Meylan, G AF Piotto, G Zoccali, M King, IR Djorgovski, SG Sosin, C Dorman, B Rich, RM Meylan, G TI Hubble Space Telescope observations of Galactic globular cluster cores. I. NGC 6362 and NGC 69341 SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : luminosity function, mass function; globular clusters : individual (NGC 6362, NGC 6934); stars : low-mass, brown dwarfs ID RR LYRAE STARS; LUMINOSITY FUNCTION; BLUE STRAGGLERS; HST OBSERVATIONS; CCD PHOTOMETRY; GIANT; METALLICITY; EVOLUTION; MASS; AGES AB We present observations of the centers of the Galactic globular clusters NGC 6362 and NGC 6934 obtained with the Hubble Space Telescope/Wide Field Planetary Camera 2 as part of the snapshot program GO-7470. The B, V color-magnitude diagrams (CMDs) are presented for 4104 stars in NGC 6362 and for 8187 stars in NGC 6934. From the CMDs, we obtain (m - M)(V) = 14.67 +/- 0.20 and E(B - V) = 0.06 +/- 0.03 for NGC 6362 and (m - M)(V) = 16.37 +/- 0.20 and E(B - V) = 0.05 +/- 0.02 for NGC 6934. Each cluster shows a well-defined sequence of blue stragglers. Both the CMD and the luminosity function (LF) of the blue stragglers differ in the two clusters, suggesting two different origins for these stars. NGC 6362 has a strikingly narrow blue straggler sequence. The data have also been used to derive a complete LF, which extends from the red giant branch tip to 2-3 mag below the turnoff. In the case of NGC 6362. which has the deepest LF, the theoretical LF cannot match both the evolved LF and that of the main sequence with any reasonable mass-function slope. The LF has also been used to estimate the ages of the two clusters. A comparison with the theoretical LF, the more classical isochrone fitting, and the Delta V-HB(TO) suggest an age between 13 and 16 Gyr for both clusters. No significant age difference between NGC 6362 and NGC 6934 is observed. C1 Univ Padua, Dipartimento Astron, I-35122 Padua, Italy. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. CALTECH, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. Univ Calif Los Angeles, Dept Phys & Astron, Div Astron & Astrophys, Los Angeles, CA 90095 USA. European So Observ, D-85748 Munich, Germany. RP Univ Padua, Dipartimento Astron, Vicolo Osservatorio 5, I-35122 Padua, Italy. EM piotto@pd.astro.it; zoccali@pd.astro.it; king@glob.berkeley.edu; george@deimos.caltech.edu; csosin@sirius.com; dorman@parfait.gsfc.nasa.gov; rmr@astro.ucla.edu; gmeylan@eso.org OI Piotto, Giampaolo/0000-0002-9937-6387 NR 59 TC 40 Z9 41 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 JAN PY 1999 VL 117 IS 1 BP 264 EP 276 DI 10.1086/300678 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 158GU UT WOS:000078108300026 ER PT J AU Brandt, JC Heap, SR Beaver, EA Boggess, A Carpenter, KG Ebbets, DC Hutchings, JB Jura, M Leckrone, DS Linsky, JL Maran, SP Savage, BD Smith, AM Trafton, LM Walter, FM Weymann, RJ Howk, JC Snow, M Ake, TB Sembach, KR AF Brandt, JC Heap, SR Beaver, EA Boggess, A Carpenter, KG Ebbets, DC Hutchings, JB Jura, M Leckrone, DS Linsky, JL Maran, SP Savage, BD Smith, AM Trafton, LM Walter, FM Weymann, RJ Howk, JC Snow, M Ake, TB Sembach, KR TI Echelle spectroscopy of interstellar absorption toward mu Columbae with the Goddard high resolution spectrograph SO ASTRONOMICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : general; stars : abundances ID HUBBLE-SPACE-TELESCOPE; ULTRAVIOLET OBSERVATIONS; ALPHA ABSORPTION; ZETA-OPHIUCHI; CORONAL GAS; LOCAL CLOUD; IONIZED-GAS; HOT GAS; O VI; H-I AB Goddard High Resolution Spectrograph echelle-mode observations of the interstellar absorption lines of Mg II, Si IV, C IV, and N V toward mu Columbae (HD 38666) are presented. The observations have a spectral resolution of 3.5 km s(-1) and signal-to-noise ratios (S/Ns) of 20-200. The mu Col sight line (l = 237.degrees 3, b = -27.degrees 1, d = 0.40 kpc, z = -0.18 kpc) extends though the Local Bubble and the warm neutral, warm ionized, and hot ionized phases of the interstellar medium (ISM). The high-ionization column densities toward mu Col are log N(Si IV) = 12.16 +/- 0.05, log N(C IV) = 12.88 +/- 0.02, and log N(N V) = 11.8-12.3. Profile fits to Copernicus satellite measures of O VI absorption toward mu Col yield log N(O VI) = 13.82+/-0.01 and b = 38.7 km s(-1). This implies N(C IV)/N(O VI) = 0.11 +/- 0.01, which is typical of the values found for the hot ISM of the Galactic disk. The O vr profile is twice as broad as the C rv and N V profiles, even though these species have roughly similar average velocities. Some of the C IV, N V, and O VI absorption toward mu Col may occur at the interface of the Local Cloud and Local Bubble, although additional contributions to these ions probably also occur in more distant gas along the sight line. A substantial part of the Si Iv absorption likely arises in warm photoionized gas in an H II region surrounding mu Col. The profile width differences among the high-ionization lines of C IV, N V, and O VI could be produced if the line of sight passes through a highly evolved supernova remnant. The observations for mu Col and for other stars observed at high resolution with the GHRS reveal that multiple gas types (warm and hot) contribute to the absorption by the highly ionized atoms along both nearby and distant sight lines. Disentangling the relative contributions from the different gas types requires high-resolution and high-S/N observations. The Mg II observations, combined with a solar Mg reference abundance, imply that the Mg depletion toward mu Col is -0.31 dex. As observed for other sight lines through the warm neutral medium, the gas-phase observations of Mg, when combined with results for Fe and Si, suggest that Mg and Fe are more deficient from the gas phase than one would expect if these elements are only contained in silicate dust grains. C1 Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Ball Aerosp & Technol Corp, Boulder, CO 80306 USA. Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. NASA, Space Sci Directorate, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Texas, McDonald Observ, Austin, TX 78712 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. SUNY Stony Brook, Dept Earth & Space Sci, Stony Brook, NY 11794 USA. Observ Carnegie Inst Washington, Pasadena, CA 91101 USA. NASA, Sci Program, Comp Sci Corp, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RP Brandt, JC (reprint author), Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA. RI heap, sara/E-2237-2012; Carpenter, Kenneth/D-4740-2012; Howk, Jay/D-2577-2013; OI SNOW, MARTIN/0000-0001-9106-1332 NR 68 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD JAN PY 1999 VL 117 IS 1 BP 400 EP 409 DI 10.1086/300673 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 158GU UT WOS:000078108300035 ER PT J AU Wilking, BA Greene, TP Meyer, MR AF Wilking, BA Greene, TP Meyer, MR TI Spectroscopy of brown dwarf candidates in the rho Ophiuchi molecular core SO ASTRONOMICAL JOURNAL LA English DT Article DE infrared radiation; ISM : individual (rho Ophiuchi cloud); stars : low-mass, brown dwarfs; stars : pre-main-sequence ID YOUNG STELLAR OBJECTS; NEAR-INFRARED SPECTRA; MAIN-SEQUENCE STARS; T-TAURI STARS; DARK-CLOUD; EVOLUTIONARY STATUS; CLUSTER; POPULATION; DISKS; PHOTOMETRY AB We present an analysis of low-resolution infrared spectra for 20 brown dwarf candidates in the core of the rho Ophiuchi molecular cloud. Fifteen of the sources display absorption-line spectra characteristic of late-type stars. By comparing the depths of water vapor absorption bands in our candidate objects with a grid of M dwarf standards, we derive spectral types that are independent of reddening. Optical spectroscopy of one brown dwarf candidate confirms the spectral type derived from the water bands. Combining their spectral types with published near-infrared photometry, effective temperatures and bolometric stellar luminosities are derived, enabling us to place our sample on the Hertzsprung-Russell diagram. We compare the positions of the brown dwarf candidates in this diagram with two sets of theoretical models in order to estimate their masses and ages. Considering uncertainties in placing the candidates in the H-R diagram, six objects consistently lie in the brown dwarf regime and another five objects lie in the transition region between stellar and substellar objects. The ages inferred for the sample are consistent with those derived for higher mass association members. Three of the newly identified brown dwarfs display infrared excesses at lambda = 2.2 mu m, suggesting that young brown dwarfs can have active accretion disks. Comparing our mass estimates of the brown dwarf candidates with those derived from photometric data alone suggests that spectroscopy is an essential component of investigations of the mass functions of young clusters. C1 Univ Missouri, Dept Phys & Astron, St Louis, MO 63121 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. RP Wilking, BA (reprint author), Univ Missouri, Dept Phys & Astron, 8001 Nat Bridge Rd, St Louis, MO 63121 USA. EM brucew@newton.umsl.edu; tgreene@mail.arc.nasa.gov; mmeyer@gould.as.arizona.edu NR 66 TC 133 Z9 133 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD JAN PY 1999 VL 117 IS 1 BP 469 EP 482 DI 10.1086/300674 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 158GU UT WOS:000078108300042 ER PT J AU van Belle, GT Lane, BF Thompson, RR Boden, AF Colavita, MM Dumont, PJ Mobley, DW Palmer, D Shao, M Vasisht, GX Wallace, JK Creech-Eakman, MJ Koresko, CD Kulkarni, SR Pan, XP Gubler, J AF van Belle, GT Lane, BF Thompson, RR Boden, AF Colavita, MM Dumont, PJ Mobley, DW Palmer, D Shao, M Vasisht, GX Wallace, JK Creech-Eakman, MJ Koresko, CD Kulkarni, SR Pan, XP Gubler, J TI Radii and effective temperatures for G, K, and M giants and supergiants SO ASTRONOMICAL JOURNAL LA English DT Article DE infrared : stars; stars : fundamental parameters; stars : late-type; techniques : interferometric ID ANGULAR DIAMETER MEASUREMENTS; INFRARED FLUX METHOD; STELLAR ATMOSPHERES; STARS; CLASSIFICATION; PHOTOMETRY; COOLER; INTERFEROMETER; PARAMETERS; CATALOG AB Interferometrically determined angular diameters obtained at the Palomar Testbed Interferometer (PTI) for 69 giant and supergiant stars are presented. Spectral types of the 59 giant stars generally lie between G6 and M6, although a B7 giant is included; the nine bright giants and supergiants have spectral types between F5 and M5. Comparison of the results to those from the IR Optical Telescope Array interferometer indicate no statistically significant difference between the two data sets. The use of Hipparcos parallaxes allows us to measure linear sizes directly for these stars, which range in size from 10 to 260 solar radii. In conjunction with previous results as reported by Dyck et al., the total of 113 giant stars provides empirically determined dependencies of effective temperature and linear radius upon spectral type and V-K color. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Wyoming, Dept Phys & Astron, Laramie, WY 82071 USA. Univ Calif San Diego, Dept Phys, La Jolla, CA 92093 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. RP van Belle, GT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 306-388, Pasadena, CA 91109 USA. NR 61 TC 158 Z9 158 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD JAN PY 1999 VL 117 IS 1 BP 521 EP 533 DI 10.1086/300677 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 158GU UT WOS:000078108300046 ER PT J AU Valinia, A Marshall, FE Kinzer, RL AF Valinia, A Marshall, FE Kinzer, RL TI Hard X-ray/soft gamma-ray observations of the Galactic Background Radiation: unresolved discrete sources? SO ASTRONOMISCHE NACHRICHTEN LA English DT Article DE Milky Way; X-rays; gamma-rays; cosmic rays ID EMISSION AB The Galactic background radiation near the Scutum Arm was observed simultaneously with the Rossi X-Ray Timing Explorer (RXTE) and the Oriented Scintillation Spectrometer Experiment (OSSE) in order to constrain the spectral shape and the origin of the emission in the hard X-ray/soft gamma-ray band. The spectrum in the 3 keV to 1 MeV band is well modeled by 4 components: a high energy continuum dominating above 500 keV that call be characterized by a power law of photon index similar to 1.6 below 1 MeV; a positron annihilation line at 511 keV and positronium continuum; a variable hard X-ray/soft gamma-ray component that dominates between 10-400 keV (with a minimum detected flux of similar to 7.7 x 10(-7) photons cm(-2) s(-1) keV(-1) deg(-2) at 100 keV averaged over the field of view of OSSE) and is well modeled by an exponentially cut off power law of photon index similar to 0.6 and energy cut off at similar to 41 keV; and finally a Raymond-Smith thermal plasma model of solar abundances and temperature similar to 2.6 keV that dominates below 10 keV. We estimate that at 60 and 100 keV, the contribution of bright discrete sources to the minimum flux detected by OSSE was similar to 49% and similar to 20%, respectively. This implies that the spectrum of the residual, unresolved emission is harder than that measured with the above power law. This emission may be interpreted either as truly diffuse emission with a hard spectrum (such as that from inverse Compton scattering) or the superposition of discrete sources that have very hard spectra. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, EO Hulburt Ctr Space Res, Res Lab, Washington, DC 20375 USA. Univ Maryland, College Pk, MD 20742 USA. RP Valinia, A (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 6 TC 0 Z9 0 U1 0 U2 1 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 179 EP 180 DI 10.1002/1521-3994(199908)320:4/5<179::AID-ASNA179>3.0.CO;2-8 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700006 ER PT J AU Loewenstein, M AF Loewenstein, M TI Heating of the ICM and cluster scaling relations SO ASTRONOMISCHE NACHRICHTEN LA English DT Article DE galaxies : clusters : general galaxies : formation AB Hydrostatic polytropic models of the intracluster medium (ICM) are presented that simultaneously explain several observed departures from predictions of basic hierarchical clustering by adding an excess heat of 3.5 keV per particle at the cluster center. This conforms with nucleosynthetic constraints derived from ICM Si measurements, if the energy injection is centrally concentrated. I argue that most of the heating occurred during the assembly of the cluster, not exclusively in pre-collapse, proto-cluster fragments. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Loewenstein, M (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 193 EP 194 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700010 ER PT J AU Petre, R Allen, GE Hwang, U AF Petre, R Allen, GE Hwang, U TI Search for X-ray evidence of cosmic ray acceleration in SNR shocks SO ASTRONOMISCHE NACHRICHTEN LA English DT Article DE supernova remnants; shock acceleration ID SUPERNOVA REMNANT; EMISSION; SN-1006; ELECTRONS; DISCOVERY; TEV AB The discovery using ASCA that the featureless X-ray spectrum from the shell of SN 1006 is produced by shock-accelerated TeV electrons, and is thus an indicator of cosmic ray acceleration, has sparked a search for X-ray spectral evidence for cosmic ray acceleration in other remnants, as well as much theoretical work. Thus far evidence for cosmic ray acceleration, in the form of synchrotron continuum components, has been found in several additional remnants, including Cas A, G347.5-0.5, and IC 443. The information provided by both detections and non-detections of these components can be used to investigate the shock acceleration process. We review the latest results of the continuing search for X-ray indicators of cosmic ray acceleration in Galactic and Magellanic Cloud SNR's and what we have learned thus far from it. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. RP Petre, R (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 14 TC 13 Z9 13 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 199 EP 202 DI 10.1002/1521-3994(199908)320:4/5<199::AID-ASNA199>3.3.CO;2-S PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700013 ER PT J AU Decourchelle, A Petre, R AF Decourchelle, A Petre, R TI Determination of the thermal and non-thermal emissions in the X-ray spectrum of Kepler's supernova remnant SO ASTRONOMISCHE NACHRICHTEN LA English DT Article DE x-rays; supernova remnant; hydrodynamics; particule acceleration ID ELECTRONS AB The objectives of this study is, by combining ASCA and XTE data, to search for a non thermal emission in the spectrum of Kepler's supernova remnant and to derive a consistent model of the thermal emission by using hydrodynamical models coupled to non equilibrium ionization calculation. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 8 TC 9 Z9 9 U1 0 U2 1 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 203 EP 204 DI 10.1002/1521-3994(199908)320:4/5<203::AID-ASNA203>3.0.CO;2-J PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700014 ER PT J AU Edwards, PG Hirabayashi, H Lovell, JEJ Piner, BG Unwin, SC Wehrle, AE AF Edwards, PG Hirabayashi, H Lovell, JEJ Piner, BG Unwin, SC Wehrle, AE TI Space VLBI observations of 3C279 with HALCA SO ASTRONOMISCHE NACHRICHTEN LA English DT Article DE galaxies : jets; quasars : individual (3C279); radio continuum; techniques : interferometric ID INTERFEROMETRY; 3C-279 AB The first VSOP (VLBI Space Observatory Programme) observations of the quasar 3C279 at 1.6 and 5 GHz were conducted in 1998 January. The quasar core and a secondary component 3 milli-arcseconds away dominate the compact radio emission, with synchrotron self-absorption in the core resulting in the jet component appearing brighter at 1.6 GHz. C1 Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Edwards, PG (reprint author), Inst Space & Astronaut Sci, Yoshinodai 3-1-1, Sagamihara, Kanagawa 2298510, Japan. NR 7 TC 1 Z9 1 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 230 EP 231 DI 10.1002/1521-3994(199908)320:4/5<230::AID-ASNA230>3.3.CO;2-A PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700024 ER PT J AU Madejski, G Done, C Zycki, P AF Madejski, G Done, C Zycki, P TI Black holes in AGN: recent results on IC 4329a and NGC 4945 SO ASTRONOMISCHE NACHRICHTEN LA English DT Article DE galaxies : active; X-rays; gamma-rays ID COLD MATTER; GALAXY; DISK; NGC-4945; NGC-4258; EMISSION; NUCLEI AB This paper briefly reviews the observations which provide the best evidence for the presence of black holes in active galaxies: kinematic studies using optical emission lines as well as the distribution of megamaser spots; X-ray variability; and the profile of the Fe K alpha X-ray emission line. It summarizes the current popular models for the radiative processes operating in radio-quiet AGN. Finally, it presents two recent X-ray observations of AGN, where (1) the shape of the Fe K line indicates a diversity of locations where such lines originate (based on the ASCA & RXTE data for IC 4329a and NGC 5548), and (2) the rapid hard X-ray variability measured with the RXTE in the heavily absorbed Seyfert 2 NGC 4945 implies that the Thomson-thick absorber surrounding the nucleus (with tau similar or equal to 2.4) is unlikely to subtend a large solid angle to the nucleus, meaning that it is not geometrically thick, but is confined to a rather thin, disk-like structure. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Madejski, G (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 25 TC 0 Z9 0 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 240 EP 243 DI 10.1002/1521-3994(199908)320:4/5<240::AID-ASNA240>3.0.CO;2-F PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700027 ER PT J AU Harding, AK AF Harding, AK TI Theory of magnetars SO ASTRONOMISCHE NACHRICHTEN LA English DT Article DE stars : neutron; gamma-ray bursts : soft gamma-ray repeaters ID MAGNETIZED NEUTRON-STARS; GAMMA-RAY BURSTS; X-RAY; REPEATERS; PULSARS AB The discovery of long periods and high period derivatives in soft gamma-ray repeaters (SGRs) over the past year has raised the possibility that magnetars, neutron stars having magnetic fields above 10(14) G, may be real astrophysical objects. Magnetars are possibly the first astrophysical sources to derive their primary radiation power from magnetic energy,which substantially exceeds their rotational energy. In addition, the physics of supercritical magnetic fields operates in a more exotic realm than even that of normal pulsars. I will discuss acceleration and radiation models for the SGR. bursts and quiescent emission from SGRs and anomalous X-ray pulsars. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Harding, AK (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 18 TC 3 Z9 3 U1 0 U2 1 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 260 EP 262 DI 10.1002/1521-3994(199908)320:4/5<260::AID-ASNA260>3.3.CO;2-Z PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700035 ER PT J AU White, NE Tananbaum, H AF White, NE Tananbaum, H TI The Constellation X-ray mission SO ASTRONOMISCHE NACHRICHTEN LA English DT Article DE X-rays; spectroscopy; constellation-X; abundances AB Constellation-X combines both the large collecting area and sensitive spectrometers required to obtain high spectral resolution, broad bandpass (0.25-40 keV) spectroscopy for all classes of X-ray sources, over a wide range of luminosity and redshift. It represents a major advance in sensitivity, providing up to a factor of 100 increase in throughput over currently planned high resolution (R > 300) X-ray; spectroscopy missions. Constellation-X is the X-ray equivalent of the Keck Telescope. When observations begin towards the end of the next decade, they will mark the start of a new era with high resolution X-ray spectra obtained for all classes of X-ray sources over a wide range of luminosity and distance. With its increased capabilities, Constellation-X will address many fundamental astrophysics questions such as observing the formation and evolution of clusters of galaxies; constraining the Baryon content of the Universe; determining the spin and mass of super massive black holes in AGN; and probing strong gravity in the vicinity of black holes. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP White, NE (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 280 EP 281 DI 10.1002/1521-3994(199908)320:4/5<280::AID-ASNA280>3.0.CO;2-# PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700043 ER PT J AU Dupke, R Arnaud, K AF Dupke, R Arnaud, K TI Central abundance ratios in the Perseus cluster: not resonant scattering but SN Ia enrichment SO ASTRONOMISCHE NACHRICHTEN LA English DT Article C1 Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Dupke, R (reprint author), Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 284 EP 284 DI 10.1002/1521-3994(199908)320:4/5<284::AID-ASNA284>3.0.CO;2-K PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700046 ER PT J AU Terashima, Y Ho, LC Kunieda, H Ptak, AF Serlemitsos, PJ AF Terashima, Y Ho, LC Kunieda, H Ptak, AF Serlemitsos, PJ TI ASCA observations of LINERs without broad H alpha emission SO ASTRONOMISCHE NACHRICHTEN LA English DT Article ID DWARF SEYFERT NUCLEI; SEARCH C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Carnegie Observ, Pasadena, CA 91101 USA. Nagoya Univ, Chikusa Ku, Nagoya, Aichi 4648602, Japan. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. RP Terashima, Y (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 305 EP 305 DI 10.1002/1521-3994(199908)320:4/5<305::AID-ASNA305>3.0.CO;2-7 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700067 ER PT J AU Awaki, H Sakano, M Terashima, Y Hayashida, K AF Awaki, H Sakano, M Terashima, Y Hayashida, K TI Time variability of low-luminosity AGNs SO ASTRONOMISCHE NACHRICHTEN LA English DT Article ID GALACTIC NUCLEI; BLACK-HOLE AB Ne analyzed six bright low-luminosity AGNs observed by the X-ray satellite ASCA, and discovered that low-luminosity AGNs are harbors of super massive black holes with M-BH > 5 x 10(6)M(.), where MBH is black hole mass. Since the estimated mass accretion rates (hereafter (M) over dot) were too small to create such super massive black holes, the (M) over dot in the past were probably larger than those at present. These galaxies would be candidates of QSO remnants. C1 Kyoto Univ, Dept Phys, Kyoto 6068502, Japan. Nagoya Univ, Dept Phys, Nagoya, Aichi 4648602, Japan. Osaka Univ, Dept Astrophys, Toyonaka, Osaka 5600046, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Awaki, H (reprint author), Kyoto Univ, Dept Phys, Kyoto 6068502, Japan. NR 6 TC 0 Z9 0 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 308 EP 308 DI 10.1002/1521-3994(199908)320:4/5<308::AID-ASNA308>3.0.CO;2-W PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700070 ER PT J AU Sugiho, M Tashiro, M Perlman, ES Makishima, K Stocke, JT Wang, QD Madejski, G AF Sugiho, M Tashiro, M Perlman, ES Makishima, K Stocke, JT Wang, QD Madejski, G TI ASCA observation of the BL Lac object PKS 1413+135 embedded in a spiral galaxy SO ASTRONOMISCHE NACHRICHTEN LA English DT Article ID PKS-1413+135 C1 Univ Tokyo, Bunkyo Ku, Tokyo 1130033, Japan. Univ Colorado, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sugiho, M (reprint author), Univ Tokyo, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan. NR 6 TC 2 Z9 2 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 316 EP 316 DI 10.1002/1521-3994(199908)320:4/5<316::AID-ASNA316>3.3.CO;2-R PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700078 ER PT J AU Ebisawa, K Maeda, Y Marshall, FE Valinia, A AF Ebisawa, K Maeda, Y Marshall, FE Valinia, A TI XTE scan observations of the galactic center diffuse X-ray emission SO ASTRONOMISCHE NACHRICHTEN LA English DT Article ID IRON LINE; RIDGE C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA. RP Ebisawa, K (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 5 TC 2 Z9 2 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 321 EP 321 DI 10.1002/1521-3994(199908)320:4/5<321::AID-ASNA321>3.0.CO;2-F PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700083 ER PT J AU Itoh, M Asai, K Uno, S Inoue, H Nomoto, K Suzuki, T Masai, K Marshall, F Kumagai, S Tanaka, Y AF Itoh, M Asai, K Uno, S Inoue, H Nomoto, K Suzuki, T Masai, K Marshall, F Kumagai, S Tanaka, Y TI X-ray light curve of SN1987A observed with ASCA SO ASTRONOMISCHE NACHRICHTEN LA English DT Article C1 Kobe Univ, Nada Ku, Kobe, Hyogo 6578501, Japan. Kanagawa Univ, Kanagawa Ku, Yokohama, Kanagawa 2218686, Japan. Nihon Fukushi Univ, Aichi 4750012, Japan. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Univ Tokyo, Tokyo 1130033, Japan. Tokyo Metropolitan Univ, Tokyo 1920397, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Nihon Univ, Chiyoda Ku, Tokyo 1018308, Japan. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. RP Itoh, M (reprint author), Kobe Univ, Nada Ku, Tsurukabuto 3-11, Kobe, Hyogo 6578501, Japan. RI Nomoto, Ken'ichi/A-4393-2011 NR 2 TC 1 Z9 1 U1 0 U2 1 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 333 EP 333 DI 10.1002/1521-3994(199908)320:4/5<333::AID-ASNA333>3.3.CO;2-V PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700095 ER PT J AU Kotani, T Band, D Cherepashchuk, AM Hjellming, RM Kawai, N Matsuoka, M Namiki, M Oka, T Shirasaki, Y Tsutsumi, T AF Kotani, T Band, D Cherepashchuk, AM Hjellming, RM Kawai, N Matsuoka, M Namiki, M Oka, T Shirasaki, Y Tsutsumi, T TI Multi-wavelength observations of the jet sources SS 433 and XTE J1748-288 SO ASTRONOMISCHE NACHRICHTEN LA English DT Article C1 RIKEN, Cosm Radiat Lab, Wako, Saitama 3510198, Japan. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Moscow MV Lomonosov State Univ, Sternberg Astron Inst, Moscow 119899, Russia. Natl Radio Astron Observ, Socorro, NM 87801 USA. Natl Astron Observ, Mitaka, Tokyo 1818588, Japan. RP Kotani, T (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. NR 4 TC 3 Z9 3 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI WEINHEIM PA BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 335 EP 335 DI 10.1002/1521-3994(199908)320:4/5<335::AID-ASNA335>3.0.CO;2-W PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700097 ER PT J AU Gierlinski, M Maciolek-Niedzwiecki, A Magdziarz, P Ebisawa, K AF Gierlinski, M Maciolek-Niedzwiecki, A Magdziarz, P Ebisawa, K TI Application of a relativistic accretion disc model to GRO J1655-40 ASCA spectrum SO ASTRONOMISCHE NACHRICHTEN LA English DT Article ID BLACK-HOLE C1 Jagiellonian Univ Observ, PL-30244 Krakow, Poland. Copernicus Astron Ctr, PL-00716 Warsaw, Poland. Univ Lodz, Dept Phys, PL-90236 Lodz, Poland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gierlinski, M (reprint author), Jagiellonian Univ Observ, Orla 171, PL-30244 Krakow, Poland. NR 6 TC 0 Z9 0 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 350 EP 350 DI 10.1002/1521-3994(199908)320:4/5<350::AID-ASNA350>3.0.CO;2-7 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700112 ER PT J AU Kubota, A Marshall, F Makishima, K Dotani, T Ueda, Y Negoro, H AF Kubota, A Marshall, F Makishima, K Dotani, T Ueda, Y Negoro, H TI ASCA observations of the X-ray transient XTE J1550-564: change of accretion disk parameters SO ASTRONOMISCHE NACHRICHTEN LA English DT Article C1 Univ Tokyo, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. ISAS, Kanagawa, Japan. RIKEN, Wako, Saitama 35101, Japan. RP Kubota, A (reprint author), Univ Tokyo, Dept Phys, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan. NR 4 TC 3 Z9 3 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 353 EP 353 DI 10.1002/1521-3994(199908)320:4/5<353::AID-ASNA353>3.0.CO;2-W PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700115 ER PT J AU Okajima, T Yamashita, K Serlemitsos, PJ Tueller, J Barthelmy, SD Chan, KW Furuzawa, A Ichimaru, S Haga, K Kunieda, H Ogasaka, Y Soong, Y Stahl, CM Takata, H Tamura, K Tawara, Y AF Okajima, T Yamashita, K Serlemitsos, PJ Tueller, J Barthelmy, SD Chan, KW Furuzawa, A Ichimaru, S Haga, K Kunieda, H Ogasaka, Y Soong, Y Stahl, CM Takata, H Tamura, K Tawara, Y TI Developments of the supermirror hard X-ray telescope at Nagoya University SO ASTRONOMISCHE NACHRICHTEN LA English DT Article C1 Nagoya Univ, Dept Phys, Nagoya, Aichi 4648602, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Okajima, T (reprint author), Nagoya Univ, Dept Phys, Nagoya, Aichi 4648602, Japan. RI Tueller, Jack/D-5334-2012; Barthelmy, Scott/D-2943-2012 NR 1 TC 0 Z9 0 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0004-6337 J9 ASTRON NACHR JI Astro. Nachr. PY 1999 VL 320 IS 4-5 BP 374 EP 374 DI 10.1002/1521-3994(199908)320:4/5<374::AID-ASNA374>3.0.CO;2-K PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 266AD UT WOS:000084277700136 ER PT J AU Duari, D Cherchneff, I Willacy, K AF Duari, D Cherchneff, I Willacy, K TI Carbon molecules in the inner wind of the oxygen-rich Mira IK Tauri SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE stars : abundances; stars : AGB and post-AGB; stars : circumstellar matter; stars : late-type ID LONG-PERIOD VARIABLES; CIRCUMSTELLAR ENVELOPES; BEARING MOLECULES; O-RICH; EMISSION; STARS AB The gas-phase non-equilibrium chemistry of the inner wind of the oxygen-rich Mira variable IK Tau (MML Tau) is investigated using a physio-chemical model describing the periodically shocked gas close to the stellar photosphere. We predict the formation in large amounts of a few carbon species in the inner envelope, in particular CO2, which has been recently detected with ISO in the spectra of several oxygen-rich semi-regular and Mira stars. The theoretical abundances are also in excellent agreement with values derived from millimeter and sub-millimeter observations, pointing to the fact that some carbon species in oxygen stars do form from shock chemistry in the inner layers and travel the envelope as "parent" species. C1 UMIST, Dept Phys, Manchester M60 1QD, Lancs, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Duari, D (reprint author), UMIST, Dept Phys, POB 88, Manchester M60 1QD, Lancs, England. EM dpd@saturn.phy.umist.ac.uk NR 22 TC 64 Z9 64 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JAN PY 1999 VL 341 IS 2 BP L47 EP L50 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 157QC UT WOS:000078072300007 ER PT J AU Stanghellini, C O'Dea, CP Murphy, DW AF Stanghellini, C O'Dea, CP Murphy, DW TI A VLBI study of GHz-Peaked-Spectrum radio sources - II. Additional VLBI images at 6 cm SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE galaxies : active; quasars : general; radio continuum : galaxies ID COMPACT SYMMETRICAL OBJECTS; STEEP-SPECTRUM; EVOLUTION; SAMPLE AB We present VLBI observations at 5 GHz of 11 GHz Peaked Spectrum (GPS) or candidate GPS sources. TWO Of them belong to the complete sample defined by Stanghellini et al. (1998) (the GPS 1 Jy sample), while the others are selected from a heterogeneous list compiled by O'Dea et al. (1991). Morphologies of the sources presented here are similar to those found in Stanghellini et al. (1997) and in the small Compact Steep Spectrum (CSS) sources studied by Dallacasa et al. (1995). Our results strengthen the evidence that GPS quasars tend to have core-jet or complex morphology and GPS galaxies tend to be compact symmetric objects (CSO). C1 CNR, Ist Radioastron, I-96017 Noto SR, Italy. Space Telescope Sci Inst, Baltimore, MD 21218 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Stanghellini, C (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. OI Stanghellini, Carlo/0000-0002-6415-854X NR 28 TC 21 Z9 21 U1 0 U2 0 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD JAN PY 1999 VL 134 IS 2 BP 309 EP 316 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 161NC UT WOS:000078294400011 ER PT J AU Ghosh, KK Apparao, KMV Pukalenthi, S AF Ghosh, KK Apparao, KMV Pukalenthi, S TI Observations of Bn and An stars: New Be stars SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE stars : emission-line, Be ID BRIGHT AB From a survey of spectra of Bn/An stars; we have detected seven new Be stars: HR 1056 (A0Vn), 1544 (A1Vn), 2191 (A0Vnn), 2300 (B8Vn), 3134 (B9.5 Vn); 3878 (B0.5 IIIn) and 4552 (B9IIIpSi). H-alpha profiles of these stars are presented. Measured values of equivalent widths, full widths at half intensity maximum, and the peak-separations of the H-alpha emission profiles are also tabulated in this paper. We have also computed the radii of emission disks of the newly detected Be stars. C1 Indian Inst Astrophys, Vainu Bappu Observ, Vellore 635701, Tamil Nadu, India. NASA, Space Sci Lab, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Bombay, Dept Phys, Bombay 400098, Maharashtra, India. RP Ghosh, KK (reprint author), Indian Inst Astrophys, Vainu Bappu Observ, Vellore 635701, Tamil Nadu, India. EM kajal.ghosh@msfc.nasa.gov; aprao@tifrvax.tifr.res.in NR 13 TC 3 Z9 3 U1 0 U2 0 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD JAN PY 1999 VL 134 IS 2 BP 359 EP 364 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 161NC UT WOS:000078294400015 ER PT J AU Melchior, AL Afonso, C Ansari, R Aubourg, E Baillon, P Bareyre, P Bauer, F Beaulieu, JP Bouquet, A Brehin, S Cavalier, F Char, S Couchot, F Coutures, C Ferlet, R Fernandez, J Gaucherel, C Giraud-Heraud, Y Glicenstein, JF Goldman, B Gondolo, P Gros, M Guibert, J Hardin, D Kaplan, J de Kat, J Lachieze-Rey, M Laurent, B Lesquoy, E Magneville, C Mansoux, B Marquette, JB Maurice, E Milsztajn, A Moniez, M Moreau, O Moscoso, L Palanque-Delabrouille, N Perdereau, O Prevot, L Renault, C Queinnec, F Rich, J Spiro, M Vidal-Madjar, A Vigroux, L Zylberajch, S AF Melchior, AL Afonso, C Ansari, R Aubourg, E Baillon, P Bareyre, P Bauer, F Beaulieu, JP Bouquet, A Brehin, S Cavalier, F Char, S Couchot, F Coutures, C Ferlet, R Fernandez, J Gaucherel, C Giraud-Heraud, Y Glicenstein, JF Goldman, B Gondolo, P Gros, M Guibert, J Hardin, D Kaplan, J de Kat, J Lachieze-Rey, M Laurent, B Lesquoy, E Magneville, C Mansoux, B Marquette, JB Maurice, E Milsztajn, A Moniez, M Moreau, O Moscoso, L Palanque-Delabrouille, N Perdereau, O Prevot, L Renault, C Queinnec, F Rich, J Spiro, M Vidal-Madjar, A Vigroux, L Zylberajch, S TI AGAPEROS: Searching for microlensing in the LMC with the pixel method - I. Data treatment and pixel light curves production SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE methods : data analysis; techniques : photometric; Galaxy : halo; galaxies : Magellanic Clouds; Cosmology : dark matter; Cosmology : gravitational lensing ID LARGE MAGELLANIC CLOUD; DARK-MATTER; UNRESOLVED STARS; GALACTIC BULGE; HALO; NUCLEOSYNTHESIS; MASS; BAR AB Recent surveys monitoring millions of light curves of resolved stars in the LMC have discovered several microlensing events. Unresolved stars could however significantly contribute to the microlensing rate towards the LMC. Monitoring pixels, as opposed to individual stars, should be able to detect stellar variability as a variation of the pixel flux. We present a first application of this new type of analysis (Pixel Method) to the LMC Bar. Mie describe the complete procedure applied to the EROS 91-92 data (one tenth of the existing CCD data set) in order to monitor pixel fluxes. First, geometric and photometric alignments are applied to each image. Averaging the images of each night reduces significantly the noise level. Second, one light curve for each of the 2.1 10(6) pixels is built and pixels are lumped into 3.6 " x 3.6 " super pixels, one for each elementary pixel. An empirical correction is then applied to account for seeing variations. We find that the final super-pixel light curves fluctuate at a level of 1.8% of the flux in blue and 1.3% in red. We show that this noise level corresponds to about twice the expected photon noise and confirms previous assumptions used for the estimation of the contribution of unresolved stars. We also demonstrate our ability to correct very efficiently for seeing variations affecting each pixel flux. The technical results emphasised here show the efficacy of the Pixel Method and allow us to study luminosity variations due to possible microlensing events and variable stars in two companion papers. C1 Univ London Queen Mary & Westfield Coll, Astron Unit, London E1 4NS, England. Coll France, Lab Phys Corpusculaire & Cosmol, UMR 7535, F-75231 Paris 05, France. Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. CEA, DSM, DAPNIA, Ctr Etud Saclay, F-91191 Gif Sur Yvette, France. Univ Paris 11, CNRS, IN2P3, Lab Accelerateur Lineaire, F-91405 Orsay, France. CERN, CH-1211 Geneva 23, Switzerland. Inst Astrophys Paris, CNRS, F-75014 Paris, France. Univ La Serena, Fac Ciencias, Dept Fis, La Serena, Chile. Max Planck Inst Phys & Astrophys, D-80805 Munich, Germany. Observ Paris, INSU, Ctr Anal Inages, F-75014 Paris, France. Observ Marseille, F-13248 Marseille 04, France. RP Melchior, AL (reprint author), Univ London Queen Mary & Westfield Coll, Astron Unit, Mile End Rd, London E1 4NS, England. EM A.L.Melchior@qmw.ac.uk RI Bauer, Florian/G-8816-2011; OI Gondolo, Paolo/0000-0002-8071-8535 NR 38 TC 11 Z9 11 U1 0 U2 0 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD JAN PY 1999 VL 134 IS 2 BP 377 EP 391 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 161NC UT WOS:000078294400018 ER PT J AU Turner, TJ George, IM Grupe, D Nandra, K Remillard, RA Leighly, KM Marshall, HL Kraemer, SB Crenshaw, DM AF Turner, TJ George, IM Grupe, D Nandra, K Remillard, RA Leighly, KM Marshall, HL Kraemer, SB Crenshaw, DM TI X-ray observations of the Seyfert galaxy LB 1727 (1H 0419-577) SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (LB 1727, 1H 0419 - 577); galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies ID GAS IMAGING SPECTROMETER; ALL-SKY SURVEY; EXTREME-ULTRAVIOLET; SOURCE CATALOG; QUASARS; ASCA; VARIABILITY; SPECTRUM; EXCESS; CONTINUUM AB We discuss the properties of the Seyfert 1.5 galaxy LB 1727, also known as 1H 0419 - 577, from X-ray observations obtained by ASCA and ROSAT, along with optical observations from earlier epochs, The source flux was F2-10 similar or equal to 10(-11) ergs cm(-2) s(-1) during the ASCA observations that were carried out during 1996 July-August, and we find only modest (less than or similar to 20%) variations in the Bur in this band within or between these observations. In contrast, a daily monitoring campaign over 1996 June-September by the ROSAT HRI instrument reveals the soft X-ray (0.1-2 keV) flux to have increased by a factor of similar or equal to 3. Significant: variations were also observed down to timescales of similar to 40 ks. We find that the 2-10 keV continuum can be parameterized as a power law with a photon index Gamma similar to 1.45-1.68 across similar to 0.7-11 keV in the rest frame. We also report the first detection of iron Ka line emission in this source. Simultaneous ASCA and ROSAT data show the X-ray spectrum to steepen sharply at a rest energy similar to 0.75 keV, so the spectrum below this energy can be parameterized as a power law of slope Gamma similar to 3.6. The X-ray emission appears to be unattenuated, and we find that ionized gas alone cannot produce such a sharp spectral break. Even allowing the presence of such gas, the simultaneous ASCA and HRI data demonstrate that the underlying continuum is required to steepen below similar to 0.75 keV. Thus LB 1727 is one of the Few Seyferts for which we can rule out the possibility that the presence of a warm absorber is solely responsible for the spectral steepening in the soft X-ray regime. Consideration of the overall spectral energy distribution for this source indicates the presence of a pronounced XUV bump visible in optical, ultraviolet, and soft X-ray data. The source appears relatively weak in infrared emission; and so if dust exists in the source, it is not excited by the nuclear radiation. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Washington, DC USA. MPE, D-85748 Garching, Germany. MIT, Cambridge, MA 02139 USA. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. RP Turner, TJ (reprint author), Univ Maryland Baltimore Cty, Dept Phys, Baltimore, MD 21250 USA. NR 49 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP 178 EP 187 DI 10.1086/306573 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NG UT WOS:000079157400016 ER PT J AU Devine, D Bally, J AF Devine, D Bally, J TI H alpha emission 11 kiloparsecs above M82 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : starburst; galaxies : nuclei; galaxies : individual (M82) ID STARBURST GALAXY M82; INFRARED-EMISSION; M-82; DISK; GAS; CONTINUUM; REGIONS; NUCLEAR; HALO; BAR AB We report the discovery of H alpha emission associated with the redshifted lobe of the M82 superwind extending out to a projected distance of 11 kpc from the disk of M82, which is 3 times farther than previously identified emission-line components associated with the nuclear superwind. The H alpha emission can be traced nearly continuously for 10' northwest of M82 out to an emission-line structure (the "cap") that lies at a projected distance of 11-12 kpc from the M82 nucleus. The cap has a shell-like morphology, is blueshifted by 50-200 km s(-1) relative to the M82 nucleus, and is visible in a ROSAT PSPC image of the region. We consider two possible models for the H alpha bright cap: it may be a bow shock formed by the impact of the superwind, either with previously emitted wind material or with ambient intergalactic material and/or tidal debris left over from the interaction between M81 and M82; or it may trace photoionized material illuminated by Lyman continuum photons leaking out of the M82 nuclear region through the hot bipolar cavity produced by the starburst-driven superwind. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. RP Devine, D (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. EM devine@h2.gsfc.nasa.gov; bally@nebula.colorado.edu NR 36 TC 60 Z9 60 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP 197 EP 204 DI 10.1086/306582 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NG UT WOS:000079157400018 ER PT J AU Wannier, P Andersson, BG Penprase, BE Federman, SR AF Wannier, P Andersson, BG Penprase, BE Federman, SR TI The Perseus B5 molecular cloud halo: Measurements of pressure, temperature, and composition SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : individual (B5); ISM : molecules; ultraviolet : ISM ID WARM NEUTRAL HALOS; HIGH-RESOLUTION SPECTROGRAPH; DIFFUSE INTERSTELLAR CLOUDS; CARBON-MONOXIDE; H-I; OSCILLATOR-STRENGTHS; PHYSICAL CONDITIONS; C-I; ZETA-OPHIUCHI; EMISSION AB We present GHRS observations of interstellar C I and CO toward three stars located in the direction of the Perseus region near the B5 molecular cloud and discuss these together with published results from a fourth sight line. The column densities of the three fine-structure levels of C I are used together with ground-based optical data and published ultraviolet data to yield several properties of the gas along the stellar sight lines. The selected stars probe gas located in the neutral envelope surrounding the dense molecular cloud. The gas pressure is tightly constrained by our observations, yielding a value of approximate to 2200 K cm(-3) in the vicinity of B5, somewhat higher than in the surrounding interstellar medium. We also present estimates of the kinetic temperature, based on observations of H-2 and C-2, yielding 20-60 K in the vicinity of B5. Together with the pressure determination, this implies a local gas density of 35-100 cm(-3), very close to that which would be implied by the observed H-2 column density assuming a filling factor of unity. This result provides additional support to the notion that the gas is part of an extensive, uniform gaseous halo surrounding the B5 cloud. The combination of temperature and pressure suggests that the diffuse gas may be part of a general outflow from the dense molecular cloud. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Pomona Coll, Claremont, CA 91711 USA. Univ Toledo, Toledo, OH 43606 USA. RP Wannier, P (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 50 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP 291 EP 304 DI 10.1086/306554 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NG UT WOS:000079157400026 ER PT J AU Kotani, T Dotani, T Nagase, F Greenhill, JG Pravdo, SH Angelini, L AF Kotani, T Dotani, T Nagase, F Greenhill, JG Pravdo, SH Angelini, L TI ASCA and Ginga observations of GX 1+4 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : symbiotic; pulsars : individual (GX 1+4); X-rays : stars ID X-RAY-EMISSION; IMAGING SPECTROMETER; DISK ACCRETION; BINARY GX-1+4; PULSE PROFILE; NEUTRON STARS; MASS-TRANSFER; SPIN-DOWN; IRRADIATION; SATELLITE AB The X-ray binary pulsar GX 1+4 was observed with Ginga every year from 1987 to 1991 and with ASCA in 1994. During the Ginga observations, GX 1+4 was in the steady spin-down phase, although the X-ray flux was not steady. Assuming a distance of 10 kpc, the absorption-corrected X-ray luminosity decreased down to L2-20 keV = 2.7 x 10(36) ergs s(-1) in 1991, after the peak activity of L2-20 keV = 1.2 x 10(37) ergs s(-1) in 1989. On the other hand, the absorption column density showed a drastic increase over the Ginga observation series. It was less than 10(23) cm(-2) at the beginning of the series, and it reached a maximum of (1.4 +/- 0.2) x 10(24) cm(-2) in 1991, indicating a rapid accumulation of matter in the vicinity of the source. The center energy and equivalent width of the iron line were consistent with emission by isotropically distributed cold matter. The ASCA observation was performed on 1994 September 15, a month before the transition into a spin-up phase. The source brightened again to L2-20 keV = 10(37) ergs s(-1). The absorption column density was observed to decrease for the first time to (2.08 +/- 0.02) x 10(23) cm(-2). The ionization degree of iron in the absorbing matter was determined to be Fe I-Fe IV using the ratio of the line-center energy to the absorption-edge energy. The low ionization degree is consistent with an absorbing matter distribution extending similar to 10(12) cm from the source. We compared the results with optical observations and found that the optical data also supports the picture. Based on the geometrical model, possible causes of the bimodal behavior of the source are discussed. C1 RIKEN, Cosm Radiat Lab, Wako, Saitama 3510198, Japan. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. Univ Tasmania, Dept Phys, Hobart, Tas 7001, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, High Energy Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kotani, T (reprint author), RIKEN, Cosm Radiat Lab, Wako, Saitama 3510198, Japan. EM kotani@riken.go.jp; dotani@astro.isas.ac.jp; nagase@astro.isas.ac.jp; John.Greenhill@utas.edu.au; Steven.H.Pravdo@jpl.nasa.gov; angelini@lheavx.gsfc.nasa.gov RI Greenhill, John/C-8367-2013 NR 48 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP 369 EP 378 DI 10.1086/306552 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NG UT WOS:000079157400031 ER PT J AU Sitko, ML Grady, CA Lynch, DK Russell, RW Hanner, MS AF Sitko, ML Grady, CA Lynch, DK Russell, RW Hanner, MS TI Cometary dust in the debris disks of HD 31648 and HD 163296: Two "baby" beta Pictoris stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; circumstellar matter; comets : general; stars : individual (HD 31648, HD 163296); stars : pre-main-sequence ID MAIN-SEQUENCE STARS; HALE-BOPP C/1995-O1; INTERPLANETARY DUST; CIRCUMSTELLAR DISKS; ZODIACAL LIGHT; PARTICLES; SILICATES; SPECTRUM; GRAINS; GAS AB The debris disks surrounding the pre-main-sequence stars HD 31648 and HD 163296 were observed spectroscopically between 3 and 14 mu m. Both stars possess a silicate emission Feature at 10 mu m that resembles that of the star beta Pictoris and those observed in solar system comets. The structure of the band is consistent with a mixture of olivine and pyroxene material, plus an underlying continuum of unspecified origin. The similarity in both size and structure of the silicate band suggests that the material in these systems had a processing history similar to that in our own solar system prior to the time that the grains were incorporated into comets. C1 Univ Cincinnati, Dept Phys, Cincinnati, OH 45221 USA. Eureka Sci, Oakland, CA 94602 USA. Aerosp Corp, Los Angeles, CA 90009 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sitko, ML (reprint author), Univ Cincinnati, Dept Phys, Cincinnati, OH 45221 USA. NR 33 TC 44 Z9 44 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP 408 EP 412 DI 10.1086/306586 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NG UT WOS:000079157400034 ER PT J AU Torsti, J Kocharov, LG Teittinen, M Thompson, BJ AF Torsti, J Kocharov, LG Teittinen, M Thompson, BJ TI Injection of greater than or similar to 10 MeV protons in association with a coronal Moreton wave SO ASTROPHYSICAL JOURNAL LA English DT Article DE interplanetary medium; Sun : corona; Sun : particle emission; waves ID ENERGETIC PARTICLES; INTERPLANETARY SHOCKS; CHARGE-STATE; ACCELERATION; SPECTRA; NUCLEON; IONS AB We report extreme-UV observations of the coranal Moreton wave and concurrent observations of similar to 10-100 MeV protons. Observations are carried out with the Extreme-UV Imaging Telescope and the Energetic and Relativistic Nuclei and Electron instrument on board the SOHO spacecraft. We study the proton events associated with coronal mass ejections (CMEs) centered near the central meridian. Observations reveal the initial injection of greater than or similar to 10 MeV protons during the period when the coronal Moreton wave was traversing the western hemisphere of the Sun, this being an early signature of the CME launch. Acceleration of the CME-associated protons starts during the CME liftoff, while the main proton production occurs several hours later, when the CME expands in the interplanetary medium. Between the first proton production and the maximum intensity time, a spectral softening is observed. We analyze in detail the 1997 September 24 event. Development of the event indicates that the spectral softening may be due to a change in the acceleration regime, so the proton production starts with the less intensive but hard-spectrum injection and then moves to the more intensive but soft-spectrum injection farther from the Sun. C1 Univ Turku, Dept Phys, Lab Space Res, FIN-20014 Turku, Finland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Torsti, J (reprint author), Univ Turku, Dept Phys, Lab Space Res, FIN-20014 Turku, Finland. RI Thompson, Barbara/C-9429-2012 NR 23 TC 45 Z9 45 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP 460 EP 465 DI 10.1086/306581 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NG UT WOS:000079157400038 ER PT J AU Rovira, M Schmieder, B Demoulin, P Simnett, GM Hagyard, MJ Reichmann, E Tandberg-Hanssen, E AF Rovira, M Schmieder, B Demoulin, P Simnett, GM Hagyard, MJ Reichmann, E Tandberg-Hanssen, E TI Bright points and subflares in ultraviolet lines and X-rays SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : flares; Sun : UV radiation; Sun : x-rays, gamma rays ID SOLAR MAXIMUM MISSION; ACTIVE REGIONS; FLARES; DYNAMICS; BURSTS; UV AB We have analyzed an active region which was observed in H alpha (Multichannel Subtractive Double Pass Spectrograph), in UV lines (SMM/UVSP), and in X-rays (SMM/HXIS). In this active region there were only a few subflares and many small bright points visible in UV and in X-rays. Using an extrapolation based on the Fourier transform, we have computed magnetic field lines connecting different photospheric magnetic polarities from ground-based magnetograms. Along the magnetic inversion lines we find two different zones: (1) a high-shear region (> 70 degrees) where subflares occur, and (2) a low-shear region along the magnetic inversion line where UV bright points are observed. In these latter regions the magnetic topology is complex with a mixture of polarities. According to the velocity field observed in the Si IV lambda 1402 line and the extrapolation of the magnetic field, we notice that each UV bright point is consistent with emission from low-rising loops with downflows at both ends. We notice some hard X-ray emissions above the bright-point regions with temperatures up to 8 x 10(6) K, which suggests some induced reconnection due to continuous emergence of new flux. This reconnection is also enhanced by neighboring subflares. C1 Consejo Nacl Invest Cient & Tecn, Inst Astron & Fis Espacio, RA-1428 Buenos Aires, DF, Argentina. Observ Paris, Sect Meudon, DASOP, URA2080, F-92195 Meudon, France. Univ Oslo, Inst Theoret Astrophys, N-0315 Oslo, Norway. Univ Birmingham, Birmingham B15 2TT, W Midlands, England. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Rovira, M (reprint author), Consejo Nacl Invest Cient & Tecn, Inst Astron & Fis Espacio, CC 67,Suc 28, RA-1428 Buenos Aires, DF, Argentina. OI Demoulin, Pascal/0000-0001-8215-6532 NR 27 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP 474 EP 484 DI 10.1086/306566 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NG UT WOS:000079157400040 ER PT J AU Colavita, MM Wallace, JK Hines, BE Gursel, Y Malbet, F Palmer, DL Pan, XP Shao, M Yu, JW Boden, AF Dumont, PJ Gubler, J Koresko, CD Kulkarni, SR Lane, BF Mobley, DW van Belle, GT AF Colavita, MM Wallace, JK Hines, BE Gursel, Y Malbet, F Palmer, DL Pan, XP Shao, M Yu, JW Boden, AF Dumont, PJ Gubler, J Koresko, CD Kulkarni, SR Lane, BF Mobley, DW van Belle, GT TI The Palomar Testbed Interferometer SO ASTROPHYSICAL JOURNAL LA English DT Article DE atmospheric effects; instrumentation : detectors; instrumentation : interferometers; techniques : interferometric ID III STELLAR INTERFEROMETER AB The Palomar Testbed Interferometer (PTI) is a long-baseline infrared interferometer located at Palomar Observatory, California. It was built as a testbed for interferometric techniques applicable to the Keck Interferometer. First fringes were obtained in 1995 July. PTI implements a dual-star architecture, tracking two stars simultaneously for phase referencing and narrow-angle astrometry. The three fixed 40 cm apertures can be combined pairwise to provide baselines to 110 m. The interferometer actively tracks the white-light fringe using an array detector at 2.2 mu m and active delay lines with a range of +/-38 m. Laser metrology of the delay lines allows for servo control, and laser metrology of the complete optical path enables narrow-angle astrometric measurements. The instrument is highly automated, using a multiprocessing computer system for instrument control and sequencing. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif San Diego, San Diego, CA 92103 USA. RP Colavita, MM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 17 TC 222 Z9 223 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP 505 EP 521 DI 10.1086/306579 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NG UT WOS:000079157400043 ER PT J AU Esser, R Fineschi, S Dobrzycka, D Habbal, SR Edgar, RJ Raymond, JC Kohl, JL Guhathakurta, M AF Esser, R Fineschi, S Dobrzycka, D Habbal, SR Edgar, RJ Raymond, JC Kohl, JL Guhathakurta, M TI Plasma properties in coronal holes derived from measurements of minor ion spectral lines and polarized white light intensity SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar wind; Sun : corona; Sun : UV radiation ID SPEED SOLAR-WIND; ALFVEN WAVES; 2-FLUID MODEL; ACCELERATION; TEMPERATURE; REGION AB Recent observations of the Ly alpha lambda 1216, Mg x lambda 625, and O VI lambda 1038 spectral lines carried out with the Ultraviolet Coronagraph Spectrometer (UVCS) on board SOHO at distances in the range 1.35-2.1 R-s in the northern coronal hole are used to place limits on the turbulent wave motions of the background plasma and the thermal motions of the protons and Mg+9 and O+5 ions. Limits on the turbulent wave motion are estimated from the measured line widths and electron densities derived from white light coronagraph observations, assuming WKB approximation at radial distances-covered by the observations. It is shown that the contribution of the turbulent wave motion to the widths of the measured spectral lines is small compared to thermal broadening. The observations show that the proton temperature slowly increases between 1.35 and 2.7 R-s and does not exceed 3 x 10(6) K in that region. The temperature of the minor ions exceeds the proton temperature at all distances, but the temperatures are neither mass proportional nor mass-to -charge proportional. It is shown, for the first time, that collision times between protons and minor ions are small compared to the solar wind expansion times in the inner corona. At 1.35 R-s the expansion time exceeds the proton Mg+9 collision time by more than an order of magnitude. Nevertheless, the temperature of the Mg ions is significantly larger than the proton temperature, which indicates that the heating mechanism has to act on timescales faster than minutes. When the expansion time starts to exceed the collision times a rapid increase of the O+5 ion spectral line width is seen. This indicates that the heavier and hotter ions lose energy to the protons as long as collision frequencies are high, and that the ion spectral line width increases rapidly as soon as this energy loss stops. C1 Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Esser, R (reprint author), Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. NR 28 TC 151 Z9 153 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP L63 EP L67 DI 10.1086/311786 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NH UT WOS:000079157500015 ER PT J AU Woo, R Habbal, SR AF Woo, R Habbal, SR TI Imprint of the Sun on the solar wind SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona ID ELECTRON-DENSITY FLUCTUATIONS; SPACECRAFT; SPECTRUM; STREAMS; CORONA AB Observations of the inner corona in polarized brightness by the Mauna Loa Mk III K-coronameter at 1.15 R. and soft X-rays by Yohkoh at 1.03 R. are combined with 1995 Ulysses radio occultation measurements of the solar wind to demonstrate that the signatures of the coronal hole boundary, active regions, and bright points are present in the heliocentric distance range of 20-30 R.. The existence of these signatures in the brightness of the corona (observed by ranging measurements) and the contrast of the small-scale raylike structures comprising the corona (observed by Doppler scintillation measurements) at such distances can readily be accounted for by open field lines rooted within the complex magnetic structures of the quiet Sun, active regions, and bright points. Hence, with the exception of the small volume of interplanetary space occupied by the heliospheric current sheet that evolves from coronal streamers within a few solar radii of the Sun, small-scale raylike structures carry the imprint of the different density structures of the solar disk approximately radially into the heliosphere. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 30 TC 28 Z9 29 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JAN 1 PY 1999 VL 510 IS 1 BP L69 EP L72 DI 10.1086/311789 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 176NH UT WOS:000079157500016 ER PT J AU Kazanas, D Mastichiadis, A AF Kazanas, D Mastichiadis, A TI The origin of TeV electrons in blazars SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE accretion; black hole physics; radiation mechanisms; Compton and inverse Compton; Active Galaxies; Blazars AB There is increasing observational evidence that relativistic particles of energies similar to 1 TeV provide a significant pressure component of the plasma which powers at least some of the relativistic jets associcated with AGN. Furthermore, observations of flares with duration similar to 15 min at TeV energies indicate that the associated electrons are accelerated to the required energies on these or shorter time scales, which are comparable to the synchrotron loss time for the values of the magnetic fields thought present in these jets. As such, they push the potential acceleration mechanisms to their limits and prompt us to examine the conditions under which it may be possible for hadronic processes to provide the electrons of the requisite energies. Relativistic hadrons could presumably exist within the Row, having been accelerated efficiently near the compact object and then transported along with it, releasing their energy by an instability due to p-gamma reactions once a well defined threshold is reached. C1 NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. Univ Athens, Dept Astron, GR-15784 Athens, Greece. RP Kazanas, D (reprint author), NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 497 EP 500 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200005 ER PT J AU Chapuis, C Corbel, S Durouchoux, P Gautier, TN Mahoney, W AF Chapuis, C Corbel, S Durouchoux, P Gautier, TN Mahoney, W TI Near-infrared photometry of blazars SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE AGN; blazar; near infrared; observations ID RAY-LOUD BLAZARS; GAMMA-RAY; VARIABILITY; RADIATION; 3C-279 AB The rapid variability of blazars in almost all wavelengths is now well established. Two days of observations were conducted at the Palomar Observatory during the nights of 25 and 26February 1997 with the 5-meter Hale telescope, in order to search for rapid variability in the near-infrared (NIR) bands J, H, K-s for a selection of eight blazars. With the possible exception of 1156+295 (4C 29.45), no intraday or day-to-day variability was observed during these two nights. However, for these eight blazars, we have measured the NIR VFnu luminosities and spectral indices. II has recently been reported that the gamma-ray emission is better correlated with the near-infrared luminosity than with the X-ray luminosity (Xie et al. 1997). This correlation is suggested as a general property of blazars because hot dust is the main source of soft photons which are scattered off the relativistic jets of electrons to produce the gamma rays by inverse Compton scattering. We thus used this relationship to estimate the gamma-ray luminosity. C1 CEA Saclay, DAPNIA, Serv Astrophys, F-91191 Gif Sur Yvette, France. Univ Versailles, Dept Phys, F-78035 Versailles 3, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chapuis, C (reprint author), CEA Saclay, DAPNIA, Serv Astrophys, F-91191 Gif Sur Yvette, France. NR 11 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 541 EP 544 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200016 ER PT J AU Kubo, H Takahashi, T Madejski, G Makino, F Tashiro, M AF Kubo, H Takahashi, T Madejski, G Makino, F Tashiro, M TI ASCA observations of blazars and multiband analysis SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE blazars; non-thermal emission; radiation mechanism ID BL-LACERTAE OBJECTS AB We present multiband data for 18 blazars observed with ASCA, half of which were also observed contemporaneously with EGRET as parts of multi-wavelength campaigns. The ASCA X-ray spectra of High-energy peaked BL Lacs (HBLs) are soft, and they form the highest energy tail of the low energy (synchrotron) component. The X-ray spectra of the quasar-hosted blazars (QHBs) are hard and consistent with the lowest energy end of the high energy (HE, Compton) component. For Low-energy peaked BL Lacs (LBLs), the X-ray spectra are intermediate. We find that the radiation process responsible for the HE peak for HBLs can be explained solely by Synchrotron-Self-Compton (SSC) emission. For many QHBs, on the other hand, the gamma-rays cannot be solely due to the SSC mechanism. We consider an alternative scenario for QHBs where the SSC component dominates in the X-ray band, but it is below the observed gamma-ray spectrum. We infer the magnetic field to be 0.1 - 1 Gauss, and Lorentz factors of electrons radiating at the peak of the vF(v) spectrum of 10(3) for QHBs. This is much lower than 10(5) for HBLs. This difference is most likely due to the large photon density expected in QHBs. C1 RIKEN, Wako, Saitama 3510198, Japan. ISAS, Sagamihara, Kanagawa 2298510, Japan. NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. Univ Tokyo, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan. RP Kubo, H (reprint author), RIKEN, 2-1 Hirosawa, Wako, Saitama 3510198, Japan. NR 13 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 549 EP 552 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200018 ER PT J AU Blazejowski, M Sikora, M Madejski, GM Moderski, R AF Blazejowski, M Sikora, M Madejski, GM Moderski, R TI Interpreting the July 1997 observations of BL Lacertae SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE blazars : BL Lacertae; high energy radiation ID MULTIFREQUENCY OBSERVATIONS; GAMMA-RAYS AB We use multiwavelength data collected during the high state of BL Lacertae in July 1997 to study the high energy radiation processes that are likely to be responsible for the radiative output from relativistic jet in this object. We show that the broad-band spectrum measured in July 1997 can be explained in terms of the model where the GeV gamma-rays are produced by Comptonization of broad emission line photons, while X-rays result from Comptonization of synchrotron radiation internal to the jet. The model parameters calculated by us in this scenario are: magnetic field intensity B' similar to 1 Gauss; the bulk Lorentz factor of the jet Gamma(j) similar to 8; and the maximum electron energy gamma'(e,max) similar to 4 X 10(3). For these parameters the spectrum bleak due to synchrotron self-absorption is located at upsilon(a) similar or equal to 4 X 10(11) Hz, which is consistent with observations. C1 Copernicus Astron Ctr, PL-00716 Warsaw, Poland. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Blazejowski, M (reprint author), Copernicus Astron Ctr, Bartycka 18, PL-00716 Warsaw, Poland. NR 16 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 585 EP 588 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200027 ER PT J AU Cline, TL Barthelmy, S Butterworth, P Marshall, F Palmer, D Trombka, J Hurley, K Gold, R Mazets, E Aptekar, R Frederiks, D Golenetskii, S Il'lnskii, V Terekhov, M Kouveliotou, C Fishman, G Meegan, C AF Cline, TL Barthelmy, S Butterworth, P Marshall, F Palmer, D Trombka, J Hurley, K Gold, R Mazets, E Aptekar, R Frederiks, D Golenetskii, S Il'lnskii, V Terekhov, M Kouveliotou, C Fishman, G Meegan, C TI Precise gamma-ray burst (GRB) sources with rapid alerts SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE gamma ray bursts; soft gamma repeaters AB Gamma-ray burst afterglow studies in the optical and radio bands resulting from the source localization capabilities of BeppoSAX have revolutionized the GRB discipline. More source locations, defined to minutes of are and with delays of only hours, are needed for additional follow-on and afterglow measurements. The new, three-cornered, long-baseline interplanetary GRB network (IPN) was created in late August, 1998, with the turn-on of the Near Earth Asteroid Rendezvous (NEAR) gamma ray monitor. The great distances involved in this system will make possible GRB source localizations of adequate precision for immediate small-field astronomical studies. The rate of production should be over 20 per year. Alerts will be delayed by up to 27 hours per event, however, due to the fact of daily transmission from deep space vehicles, but some fraction of the delays will be only a few hours. The IPN now includes Ulysses, at distances of up to 6 AU, the NEAR, now over 1.3 AU away, the GGS-Wind Konus at several tight-seconds distance, and the CGRO BATSE gamma ray and RXTE x-ray experiments. Results will be distributed rapidly and automatically using the well-known GRB coordinates distribution network (GCN), that is currently processing CGRO BATSE and other GRB data to enable rapid wide-angle counterpart searches (see, e.g., S. Barthelmy et al., this Workshop). The spectacular 1979-March-5-like SGR event of 1998 August 27 was the first event found with the renewed IPN (Cline at al., IAUC 7002; Hurley et al., IAUC 7004; Marshall et al., IAUC 7005). This event, with the precisely known source direction of SGR 1900+14, confirmed the system calibration. No classical GRBs were observed in the few weeks between August turn-on and preparation for this Workshop in early September, 1998, however. Details are outlined below. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Cline, TL (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Barthelmy, Scott/D-2943-2012; Frederiks, Dmitry/C-7612-2014; Aptekar, Raphail/B-3456-2015; Golenetskii, Sergey/B-3818-2015 NR 0 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 713 EP + PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200053 ER PT J AU Kippen, RM Hurley, K Pendleton, GN AF Kippen, RM Hurley, K Pendleton, GN TI Probing the small-scale angular distribution of gamma-ray bursts with combined BATSE/Ulysses 4B locations SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE gamma-rays : bursts AB We investigate the angular distribution of gamma-ray bursts using the largest catalog of well-localized events that is currently available-combined BATSE/Ulysses burst locations. We present the preliminary spatial analysis of 415 BATSE/Ulysses bunts included in the BATSE 4B catalog. We find that the locations are consistent with large- and small-scale isotropy, with no significant clustering or repetition. We also search for cross-correlation between the BATSE/Ulysses bursts and known extragalactic objects-such as Abell galaxy clusters, radio-quiet QSO, AGN and supernovae-and place limits on the fraction of bursts that could originate from these objects. C1 Univ Alabama, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Kippen, RM (reprint author), Univ Alabama, Huntsville, AL 35899 USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 729 EP 732 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200057 ER PT J AU Vedrenne, G Schonfelder, V Albernhe, F Borrel, V Bouchet, L Caraveo, P Connell, P Cordier, B Denis, N Coszach, R Diallo, N Diehl, R Durouchoux, PH Georgii, R Jean, P Juchniewicz, J Kandel, B von Kienlin, A Lavigne, JM Leleux, P Lichti, G Lin, R Mandrou, P Matteson, J Naya, J Paul, P Roques, JP Sanchez, F Seifert, H Skinner, G Slassi, S Strong, A Teegarden, B Varendorff, M von Ballmoos, P AF Vedrenne, G Schonfelder, V Albernhe, F Borrel, V Bouchet, L Caraveo, P Connell, P Cordier, B Denis, N Coszach, R Diallo, N Diehl, R Durouchoux, PH Georgii, R Jean, P Juchniewicz, J Kandel, B von Kienlin, A Lavigne, JM Leleux, P Lichti, G Lin, R Mandrou, P Matteson, J Naya, J Paul, P Roques, JP Sanchez, F Seifert, H Skinner, G Slassi, S Strong, A Teegarden, B Varendorff, M von Ballmoos, P TI The INTEGRAL spectrometer SPI SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE instrumentation; high-resolution gamm-ray spectroscopy; INTEGRAL; SPI AB The INTEGRAL spectrometer SPI features a compact array of high purity Germanium detectors cooled by a Stirling cooler system and shielded by a EGO anticoincidence system. A coded mask modulates the astrophysical signal. In the energy range between 20 keV - 8 MeV SPI will perform spectral analysis of high-energy sources such as supernovae remnants, novae, compact Galactic sources, annihilation sites, Active Galactic Nuclei etc. The anticipated performance for narrow line spectroscopy is characterized by an energy resolution in the parts per thousand range, an angular resolution of order 2.5 degrees within a fully coded field of view of 16 degrees, and a sensitivity 3-7 10(-6) ph cm(-2) s(-1) in the energy range relevant for nuclear astrophysics. C1 CESR, Toulouse, France. MPE, Garching, Germany. CNR, IFC, I-20133 Milan, Italy. Univ Birmingham, Birmingham B15 2TT, W Midlands, England. CEA Saclay, Gif Sur Yvette, France. CBK, Warsaw, Poland. Univ Louvain, B-3001 Louvain, Belgium. SSL, Berkeley, CA USA. CASS, La Jolla, CA USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Valencia, E-46003 Valencia, Spain. RP Vedrenne, G (reprint author), CESR, Toulouse, France. RI Sanchez, Filomeno/D-7859-2014 OI Sanchez, Filomeno/0000-0003-0831-4744 NR 2 TC 2 Z9 2 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 793 EP 797 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200071 ER PT J AU Ubertini, P Lebrun, F Di Cocco, G Bazzano, A Bird, AJ Broenstad, K Caroli, E Denis, M Goldwurm, A Labanti, C Laurent, P Mirabel, IF Natalucci, L Quadrini, EM Reglero, V Sabau, L Sacco, B Staubert, R Vigroux, L Weisskopf, MC Zdziarski, A Zehnder, A Bassani, L AF Ubertini, P Lebrun, F Di Cocco, G Bazzano, A Bird, AJ Broenstad, K Caroli, E Denis, M Goldwurm, A Labanti, C Laurent, P Mirabel, IF Natalucci, L Quadrini, EM Reglero, V Sabau, L Sacco, B Staubert, R Vigroux, L Weisskopf, MC Zdziarski, A Zehnder, A Bassani, L TI The gamma-ray imager on board INTEGRAL SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY AB The Imager on-Board INTEGRAL Satellite (IBIS) is the high resolution Gamma-Ray imaging telescope on board INTEGRAL. Its scientific goal is to address, complemented by the high resolution Spectrometer (SPI), astrophysical processes from celestial sources and diffuse regions in the X and Gamma-ray domain. IRIS is an essential element with its powerful diagnostic capabilities of fine imaging source identification and spectral sensitivity to both continuum and broadened lines. It will observe, simultaneously with the other instruments on board INTEGRAL, celestial objects of all classes ranging from the most compact galactic systems to extragalactic objects. The telescope features a coded aperture mask and a novel large area (similar to 3,000 cm(2)) multilayer detector which utilises both Cadmium Telluride (16,384 detectors) and Caesium Iodide elements (4,096 detectors) to provide the fine angular resolution similar to 12 arcmin, wide spectral response (20 keV to 10 MeV), high resolution timing (60 mu s) and spectroscopy (6% at 100 keV) required to satisfy the mission's imaging objectives. C1 CNR, IAS, I-00133 Rome, Italy. CEA Saclay, Serv Astrophys, F-91191 Gif Sur Yvette, France. CNR, Ist Tesre, I-40129 Bologna, Italy. Univ Southampton, Southampton S09 5NH, Hants, England. Univ Bergen, N-5007 Bergen, Norway. Polish Acad Sci, SRC, PL-00716 Warsaw, Poland. CNR, IFCTR, Milan, Italy. Univ Valencia, E-46100 Burjassot, Spain. INTA, LAEF, Villafranca De Castillo 28691, Spain. CNR, IFCAI, I-90146 Palermo, Italy. AIT, D-72076 Tubingen, Germany. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Copernicus Ctr, PL-00716 Warsaw, Poland. Paul Scherrer Inst, CH-5232 Villigen, Switzerland. RP Ubertini, P (reprint author), CNR, IAS, Via Fosso Cavaliere, I-00133 Rome, Italy. RI laurent, philippe/E-6211-2013; Caroli, Ezio/G-1427-2012 OI Caroli, Ezio/0000-0001-8468-7433 NR 1 TC 2 Z9 2 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 799 EP + PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200072 ER PT J AU Winkler, C Gehrels, N Lund, N Schonfelder, V Ubertini, P AF Winkler, C Gehrels, N Lund, N Schonfelder, V Ubertini, P TI The INTEGRAL Core Observing Programme SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE INTEGRAL; nucleosynthesis; compact objects; high energy transients ID COMPTEL OBSERVATIONS; LINE EMISSION AB The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements of the observing programme. C1 ESA, Estec, Noordwijk, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. DSRI, Copenhagen, Denmark. MPE, Garching, Germany. IAS, Rome, Italy. RP Winkler, C (reprint author), ESA, Estec, Noordwijk, Netherlands. RI Gehrels, Neil/D-2971-2012 NR 11 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 829 EP 832 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200076 ER PT J AU Connell, PH Skinner, GK Teegarden, BG Naya, J Sturner, S AF Connell, PH Skinner, GK Teegarden, BG Naya, J Sturner, S TI Imaging and spectral reconstruction for the integral spectrometer (SPI) SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAORMINA, ITALY DE INTEGRAL; SPI; imaging; spectra AB Software has been written to model the SPI spectrometer, to simulate its response to Gamma-ray emission, to reconstruct images and extract spectra of significant sources identified. This software is now being used to investigate the capabilities of the combination of the instrument and the data analysis system to allow the extraction of spectra from multiple sources observed at the same time. Using input count data from Monte Carlo simulations of SPI exposures for fields containing point sources having different spectra we present both the image reconstruction, "raw" spectra extracted for the sources found, and the result of postprocessing and modelling using XSPEC software. C1 Univ Birmingham, Birmingham B15 2TT, W Midlands, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Connell, PH (reprint author), Univ Birmingham, Birmingham B15 2TT, W Midlands, England. NR 2 TC 0 Z9 0 U1 0 U2 1 PU GORDON BREACH PUBLISHING, TAYLOR & FRANCIS GROUP PI PHILADELPHIA PA 325 CHESTNUT ST, 8TH FL, PHILADELPHIA, PA 19106 USA SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 865 EP 868 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200085 ER PT J AU Armstrong, TW Colborn, BL Dietz, KL Ramsey, BD AF Armstrong, TW Colborn, BL Dietz, KL Ramsey, BD TI Monte Carlo simulations of background spectra in integral imager detectors SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE X-ray backgrounds; CdTe; CsI; Monte Carlo simulations AB Results from Monte Carlo simulations of x-ray backgrounds for the CdTe and CsI detectors on INTEGRAL are presented. C1 Sci Applicat Int Corp, Prospect, TN 38477 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Armstrong, TW (reprint author), Sci Applicat Int Corp, Prospect, TN 38477 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 881 EP 884 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200089 ER PT J AU White, NE Tananbaum, H AF White, NE Tananbaum, H TI The Constellation X-ray mission SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE X-rays; spectroscopy; constellation-X; abundances AB Constellation-X is the X-ray equivalent of the Keck Telescope. When observations begin towards the end of the next decade, they will mark the start of anew era with high resolution X-ray spectra obtained for all classes of X-ray sources over a wide range of luminosity and distance. With its increased capabilities, Constellation-X will address many fundamental astrophysics questions such as observing the formation and evolution of clusters of galaxies; constraining the Baryon content of the Universe;determining the spin and mass of super massive black holes in AGN; and probing strong gravity in the vicinity of black holes. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP White, NE (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 933 EP 936 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200103 ER PT J AU Mahoney, WA Varnell, LS AF Mahoney, WA Varnell, LS TI Background in CdZnTe arrays SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE instrumentation; gamma-ray astronomy ID RADIATION-DAMAGE; DETECTORS AB Cadmium Zinc Telluride (CdZnTe) arrays show great promise as the prime sensors for both focusing and non-focusing hard x-ray imaging spectrometers. However, their sensitivity will be determined to a large degree by the intensity of the induced background arising from cosmic rays. In December 1995 we investigated this background by irradiating a 10 x 10 x 3 mm(3) CdZnTe crystal with 199 MeV protons to a fluence of 5 x 10(10) protons cm(-2) at the Indiana University Cyclotron Facility. Beginning less than 3 minutes after the irradiation, and continuing for 15 months, we measured the activity of the CdZnTe with a Ge gamma-ray spectrometer. We have now developed a model to calculate the spallation products and their decay line intensities which can be used to estimate the proton-induced background in CdZnTe arrays in space-based experiments. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mahoney, WA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 1 U2 1 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 39 IS 1-6 BP 937 EP 940 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NR UT WOS:000089508200104 ER PT J AU Baring, MG Harding, AK AF Baring, MG Harding, AK TI Highly-magnetized pulsars and integral SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE pulsars : general; stars : neutron; magnetic fields; gamma rays : theory ID X-RAY PULSAR; CASCADES; SPECTRUM; FIELD AB The complete absence of radio pulsars with periods exceeding a few seconds has lead to the popular notion of the existence of a high period death line. We have recently postulated the existence of another radio quiescence boundary at high magnetic fields ( B greater than or similar to 4 x 10(13) G) in the upper portion of the period-period derivative diagram, a domain where no radio pulsars are observed. The origin of this high B boundary is also due to the suppression of magnetic pair creation, gamma --> e(+-), but mainly because of competition with the exotic QED process of magnetic photon splitting, gamma --> gamma gamma, coupled with ground state pair creation. This mechanism could also explain the low spectral cutoff energy of the gamma-ray pulsar PSR1509-58, which lies near the high B death-line. In this paper, we summarize the hypothesis of this new "death line," and discuss some subtleties of pair suppression that relate to photon polarization and positronium formation. We identify several ways in which Integral will serve as a useful tool in probing high field pulsars, given that the radio quiescence boundary is transparent to the high energy bands. C1 NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. RP Baring, MG (reprint author), NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 17 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 9 EP 12 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000004 ER PT J AU Harding, AK Daugherty, JK AF Harding, AK Daugherty, JK TI Pulsar high energy emission from polar cap cascades SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE pulsars; particle acceleration; X-rays; gamma-rays ID GAMMA-RAY PULSARS; OUTER MAGNETOSPHERE; PSR B1951+32; RADIATION AB We present model spectra in the energy range 1 keV to 100 GeV from polar cap pair cascade simulations. A Monte Carlo simulation follows the acceleration of primary electrons above a. pulsar magnetic polar cap, the curvature radiation from these electrons and the production of electron-positron pairs and their synchrotron emission. The model energy spectra of Vela, Geminga and PSR B1951+32 all predict low energy turnovers between 1 and 50 keV at the local cyclotron energy. Measurement of the spectrum of the Vela pulsar with RXTE in the energy range 2 - 30 keV seems to confirm such a spectral turnover in this source. INTEGRAL may be able to detect and study such features in the spectra of other gamma-ray pulsars. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ N Carolina, Asheville, NC 28804 USA. RP Harding, AK (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 12 TC 6 Z9 6 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 25 EP 28 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000008 ER PT J AU Boldt, E AF Boldt, E TI The extreme universe: Some views from here SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAORMINA, ITALY DE cosmic rays; gamma rays; x-rays; black holes ID ENERGY COSMIC-RAYS; BLACK-HOLES; ELECTROMAGNETIC EXTRACTION; COMPTEL OBSERVATIONS; INTERSTELLAR-MEDIUM; EGRET OBSERVATIONS; GALACTIC NUCLEI; EMISSION; AL-26; LUMINOSITY AB Forty years have passed since the first Explorer orbiting observatory - the 1958 mission used to discover the Van Alien radiation belts outside the atmosphere- ushered in the modern age of space science. Even though in situ observations of outer space are still restricted to measurements made within the solar system, we now have access to a wide range of cosmic signals, extending from the well understood microwave photons indicative of the earliest epoch of the universe to those apparently inexplicable ultra-high energy extragalactic cosmic ray particles that are too energetic (up to 50 Joules/each) to have survived passage through a cosmological extent of the pervasive thermal relic radiation field. In this lecture the extremes of cosmic ray physics are discussed within the context of particles having the lowest energy (down to similar to 10(3) eV/nucleon) and highest energy (> 10(20) eV), emphasizing those aspects of astronomy, particularly gamma-ray and x-ray, that appear to be especially revealing for these regimes. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. EM boldt@lheavx.gsfc.nasa.gov NR 79 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH PUBLISHING, TAYLOR & FRANCIS GROUP PI PHILADELPHIA PA 325 CHESTNUT ST, 8TH FL, PHILADELPHIA, PA 19106 USA SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP XXXI EP XLVI PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000002 ER PT J AU Kazanas, D Hua, XM AF Kazanas, D Hua, XM TI Probing the structure of accreting high energy sources SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE accretion; black hole physics; radiation mechanisms : Compton and inverse Compton; stars : neutron; X-rays ID X-RAY VARIABILITY AB We indicate that the Fourier frequency dependent hard X-ray lags, first observed in the analysis of aperiodic variability of the light curves of the black hole candidate Cygnus X-l, are naturally interpreted in terms of a very extended, inhomogeneous, hot electron corona. The dependence of these lags on the Fourier period, P, can be easily accommodated within this model and it is uniquely related to the density profile of the hot electrons, which one can probe through the study of the corresponding lags. We also indicate that the timing properties of black hole candidates suggest that these Fourier period dependent lags are a common property of these sources, suggesting a similarity of their structures. C1 NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. RP Kazanas, D (reprint author), NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 45 EP 48 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000013 ER PT J AU Barret, D Boirin, L Olive, JF Grindlay, JE Bloser, PF Swank, JH Smale, AP AF Barret, D Boirin, L Olive, JF Grindlay, JE Bloser, PF Swank, JH Smale, AP TI Discovery of high frequency quasi-periodic oscillations in 4U1915-05 SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE X-ray binaries; neutron star : individual 4U1915-05 AB The type I X-ray burster and dipper 4U1915-05 (also known as XB1916-053) was monitored by the Rossi X-ray Timing Explorer between February and October, 1996. The source was observed in various spectral states; the highest luminosity state (L-X similar to 1.5 x 10(37) ergs s(-1), 10 kpc, 1-20 keV) is associated with a soft spectrum, whereas for the lower luminosity state (down to similar to 5 x 10(36)ergs s(-1)) the spectrum is significantly harder. Using the high time resolution data provided by the Proportional Counter Array (PCA), we have discovered High-Frequency quasi-Periodic Oscillations (HFQPOs) in the persistent X-ray emission of 4U1915-05 while its luminosity was similar to 8 x 10(36)ergs s(-1). The QPO frequency ranges from 600 Hz up to similar to 1000 nz, with typical Full Width at Half Maximum (FWHM) similar to 50 - 100 Hz and Root Mean Squared (RMS) values similar to 15%. fn addition, by using the "shift and add" technique, we have detected a twin HFQPO (5.5 sigma level) separated from the main peak by similar to 355 Hz. 4U1915-05 is the eighth Atoll source displaying simultaneous twin HFQPOs, Based on current knowledge of HFQPO sources, our observations suggest that 4U1915-05 might contain a 2.8 (or 5.6) millisecond rotating neutron star. C1 UPS, CNRS, Ctr Etud Spatiale Rayonnements, F-31028 Toulouse 04, France. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Barret, D (reprint author), UPS, CNRS, Ctr Etud Spatiale Rayonnements, 9 Ave Colonel Roche, F-31028 Toulouse 04, France. RI Swank, Jean/F-2693-2012 NR 8 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 73 EP 76 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000019 ER PT J AU McCollough, ML Robinson, CR Zhang, SN Harmon, BA Paciesas, WS Dieters, S Phengchamnan, S Hjellming, RM Rupen, M Mioduszewski, AJ Waltman, EB Ghigo, FD Pooley, GG Fender, RP Cui, W Trushkin, S AF McCollough, ML Robinson, CR Zhang, SN Harmon, BA Paciesas, WS Dieters, S Phengchamnan, S Hjellming, RM Rupen, M Mioduszewski, AJ Waltman, EB Ghigo, FD Pooley, GG Fender, RP Cui, W Trushkin, S TI X-ray spectral behavior of the relativistic jet source Cygnus X-3 SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE Cygnus X-3; X-ray binary; radio source; relativistic jets AB Cyg X-3 is an unusual X-ray binary which shows remarkable correlative behavior between the hard X-ray, soft X-ray, and the radio. We present an analysis of these long term light curves in the context of spectral changes of the system. This analysis also incorporates a set of pointed RXTE observations made during a period when Cyg X-3 made a transition from a Baring state (including a major Rare) to a quiescent radio state. C1 Univ Space Res Assoc, Huntsville, AL 35806 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35899 USA. Natl Radio Astron Observ, VLA, JIVE, Socorro, NM 87901 USA. USN, Res Lab, Washington, DC 20375 USA. Natl Radio Astron Observ, GBI, Green Bank, WV 24944 USA. Univ Cambridge, Cavendish Lab, Mullard Radio Astron Observ, Cambridge CB3 0HE, England. Univ Amsterdam, NL-1098 SJ Amsterdam, Netherlands. MIT, Cambridge, MA 02139 USA. Russian Acad Sci, Special Astrophys Observ, Nizhni Arkhyz 357147, Russia. RP McCollough, ML (reprint author), Univ Space Res Assoc, Huntsville, AL 35806 USA. NR 7 TC 2 Z9 2 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 105 EP + PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000027 ER PT J AU Del Sordo, S Frontera, F Pian, E Piraino, S Oosterbroek, T Harmon, BA Palazzi, E Tavani, M Zhang, SN Parmar, A AF Del Sordo, S Frontera, F Pian, E Piraino, S Oosterbroek, T Harmon, BA Palazzi, E Tavani, M Zhang, SN Parmar, A TI BeppoSAX observations of the galactic source GS 1826-238 in a hard X-ray high state SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE x-ray bursts; LMXRB AB The BeppoSAX Narrow Field Instruments observed the galactic source GS 1826-238 in October 1997, following a hard X-ray burst with a peak flux of about 100 mCrab detected by BATSE. Two short X-ray bursts (similar to 150 seconds) were detected up to 60 keV, with larger amplitude and duration at lower energies (up to a factor 20 times the persistent emission). This confirms the proposed identification of the source as a weakly magnetized neutron star in a LMXRB system. For both persistent and bunt states, the spectrum in the 0.4-100 keV energy range Is well fitted by an absorbed black body, plus a flat power-law (Gamma similar to 1.7) with an exponential cutoff at 50 keV. C1 CNR, IFCAI, I-98146 Palermo, Italy. CNR, ITESRE, I-40129 Bologna, Italy. Estec, Div Astrophys, NL-2200 AG Noordwijk, Netherlands. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. CNR, IFCTR, I-20133 Milan, Italy. RP Del Sordo, S (reprint author), CNR, IFCAI, Via Ugo La Malfa, I-98146 Palermo, Italy. RI Palazzi, Eliana/N-4746-2015; Orlandini, Mauro/H-3114-2014 OI Orlandini, Mauro/0000-0003-0946-3151 NR 11 TC 5 Z9 5 U1 0 U2 1 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 125 EP 128 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000032 ER PT J AU Gruber, DE Heindl, WA Rothschild, RE Staubert, R Wilms, J Scott, DM AF Gruber, DE Heindl, WA Rothschild, RE Staubert, R Wilms, J Scott, DM TI Stability of cyclotron line in Her X-1 SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE x-rays; neutron stars; cyclotron lines; magnetic fields ID PULSE-PHASE SPECTROSCOPY; X-RAY-SPECTRUM; HERCULES-X-1 AB Four observations now of Her X-l from RXTE show steadiness of the cyclotron line centroid which limits variability to about one percent, which is well less than the 10 percent variability characteristic of the other spectral parameters. This confines the average height of scattering above the polar cap to within 35 meters, and is consistent with models which put the radiating structure within meters of the surface of the neutron star. But in other pulsars observed line centroid changes have been correlated with luminosity changes, and if interpreted as variability of the height at which scattering takes place, hundreds of meters are required. These RXTE data are not yet in conflict with such an extended radiating structure. C1 UCSD, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Univ Tubingen, Inst Astron & Astrophys, Tubingen, Germany. George C Marshall Space Flight Ctr, Huntsville, AL USA. RP Gruber, DE (reprint author), UCSD, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. RI Wilms, Joern/C-8116-2013 OI Wilms, Joern/0000-0003-2065-5410 NR 7 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 153 EP 156 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000039 ER PT J AU Laurent, P Titarchuk, L AF Laurent, P Titarchuk, L TI Monte-Carlo simulations of comptonization on free-falling electrons SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAORMINA, ITALY DE black hole physics; X-rays : general; radiation mechanism : non thermal ID SPECTRA; MODELS; RAY AB The recent observations of black hole binary systems show more and more clearly that the observed spectra of these systems result from the Comptonization of the high energy electrons close to the black hole on the ambient soft photons. So, in order to model these observed spectra, we have to treat as precisely as possible the Comptonization process, taking into account the real motion of the electrons, which is, in fact, a composition of their free-falling motion onto the black hole and of their brownian motion due to the electron temperature. Whereas the thermal Comptonization has been already explored in details. the effects of the electrons free-falling motion on the resulting Comptonized spectrum is not yet clearly understood. Also, the general relativistic effects close to the black hole were not yet plainly taken into account. We present the study of these effects by using a Monte-Carlo simulation which take into account the exact motion of the Comptonizing electrons, in a fully general relativistic treatment. Some of the results of this study will be presented here, and will give a new insight into the understanding of black hole binary spectral states. C1 CEA Saclay, SAp, DAPNIA, DSM,CEA, F-91191 Gif Sur Yvette, France. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. George Mason Univ, Inst Computat Sci & Informat, Fairfax, VA 22030 USA. RP CEA Saclay, SAp, DAPNIA, DSM,CEA, F-91191 Gif Sur Yvette, France. EM fil@mir.saclay.cea.fr RI laurent, philippe/E-6211-2013 NR 11 TC 0 Z9 0 U1 0 U2 1 PU GORDON BREACH PUBLISHING, TAYLOR & FRANCIS GROUP PI PHILADELPHIA PA 325 CHESTNUT ST, 8TH FL, PHILADELPHIA, PA 19106 USA SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 173 EP 176 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000044 ER PT J AU Zycki, PT Done, C Smith, DA AF Zycki, PT Done, C Smith, DA TI On the geometry of accretion flow in soft X-ray transients SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE accretion; accretion discs; black holes; X-ray : stars ID EVOLUTION; GINGA AB We derive constraints on geometry and physical properties of accretion flow in Soft X-ray Transient sources from detailed modeling of the effects of X-ray reprocessing in their spectra. We then compare our results with predictions of theoretical models proposed to explain the nature of spectral transitions in these sources. C1 Univ Durham, Dept Phys, Durham DH1 3LE, England. Copernicus Astron Ctr, Warsaw, Poland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Zycki, PT (reprint author), Univ Durham, Dept Phys, South Rd, Durham DH1 3LE, England. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 12 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 193 EP 196 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000049 ER PT J AU Harmon, BA AF Harmon, BA TI Galactic superluminal sources SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE superluminal jets; X-ray transients; multiwavelength observations; microquasars; GRS 1915+105; GRO J1655-40 ID SOURCE GRO J1655-40; ACCRETION DISKS; BLACK-HOLES; GRS-1915+105; JETS; OUTBURST; SPECTRA AB A new class of X-ray sources was clearly established with the discovery of highly relativistic radio jets from the galactic sources GRS 1915 + 105 and GRO J1655-40. Both of these objects have given us a broader view of black holes and the formation of jets, yet they also show the complexity of the accretion environment near relativistic objects. The fast apparent motion of the jets, their luminosity and variability, high energy spectrum, and approximate scaling to the behavior of active galactic nuclei, certainly warrant the description "microquasar". I present a review of the observational data on these sources, and discuss where we stand on a physical picture of GRS 1915 + 105 and GRO J1655-40 as taken from multi-wavelength studies. I also point out other galactic sources which share some of the properties of the microquasars, and what to look for as a high energy "signature" in future observations. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Harmon, BA (reprint author), NASA, George C Marshall Space Flight Ctr, ES84, Huntsville, AL 35812 USA. NR 26 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 209 EP 216 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000053 ER PT J AU Kotani, T Ebisawa, K Inoue, H Nagase, N Ueda, Y AF Kotani, T Ebisawa, K Inoue, H Nagase, N Ueda, Y TI Iron absorption lines of transient jets SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAORMINA, ITALY DE jet; X-ray spectroscopy; binary; GRS 1915+105; GRO J155-40 ID SUPERLUMINAL SOURCE; GRO J1655-40 AB K-line absorption features of highly ionized iron were discovered in X-ray spectra of super-luminal transient jets GRS 1915 + 105 (Ebisawa 1997; Kotani et al. 1997) and GRO J1655-40 (Ueda et al. 1998) with ASCA. The absorption features were identified as Fe XXV K alpha, Fe XXVI K alpha, and Ni XXVII K alpha resonance lines with equivalent widths of 20-50 eV. Such absorption lines have never been found in any other X-ray binary, and considered to be a peculiar characteristic of transient jets. They are evidence of highly ionized plasma in anisotropic configuration or in anisotropic illumination in the vicinity of the source. We adopted models of torus and disk-like plasma, and estimated physical parameters such as density, dimension, solid angle from the source, temperature and xi-parameter. The nature of the plasma and its implication is discussed. C1 RIKEN, Cosm Radiat Lab, Wako, Saitama 3510198, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. ISAS, High Energy Astrophys Div, Sagamihara, Kanagawa 2298510, Japan. RP RIKEN, Cosm Radiat Lab, Wako, Saitama 3510198, Japan. EM kotani@riken.go.jp NR 6 TC 1 Z9 1 U1 0 U2 0 PU GORDON BREACH PUBLISHING, TAYLOR & FRANCIS GROUP PI PHILADELPHIA PA 325 CHESTNUT ST, 8TH FL, PHILADELPHIA, PA 19106 USA SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 249 EP 252 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000062 ER PT J AU Sturner, SJ Naya, JE AF Sturner, SJ Naya, JE TI On the nature of the broad Al-26 feature observed by GRIS SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAORMINA, ITALY DE Al-26; diffuse emission; supernova remnants; dust ID SUPERNOVA-REMNANTS; DUST; GRAINS; GAS AB Recent observations of the Galactic Center region by the GRIS balloon-borne germanium spectrometer have determined that the diffuse 1809 keV emission resulting from the decay of Al-26 has an intrinsic width of 5.4 keV FWHM. This line width indicates that the Al-26 is either at a temperature of similar to 4.5 x 10(8) K or it has a nonthermal velocity of similar to 500 km/s. Previous authors have suggested that for the Al-26 to remain at this large a velocity over its 10(6) year lifetime it must be trapped within dust grains in the ISM (see e.g. Naya et al. 1996, Chen et al. 1998). In this poster we discuss the results of our model for the initial acceleration of the 26Al in dust grains as they exit their source, a Type IT supernova, and their subsequent reacceleration in the ISM by ambient supernova remnant (SNR) shocks. Our results show that dust grains can be maintained at a velocity sufficient to explain the GRIS observation for ISM densities of similar to 0.2 cm(-3), dust grain sizes near 10(-5) cm, and distances between SNR shocks in the ISM of 100 - 200 pc. C1 Univ Space Res Assoc, Seabrook, MD USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Univ Space Res Assoc, Seabrook, MD USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU GORDON BREACH PUBLISHING, TAYLOR & FRANCIS GROUP PI PHILADELPHIA PA 325 CHESTNUT ST, 8TH FL, PHILADELPHIA, PA 19106 USA SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 387 EP 390 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000093 ER PT J AU Guessoum, N Kazanas, D Ramaty, R AF Guessoum, N Kazanas, D Ramaty, R TI Production of Li, Be, B in the companions of X-ray novae SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE nuclear gamma-ray lines; X-ray binaries; Li, B, B production ID EMISSION AB We examine the processes which could lead to the observed enhancement of Li and possibly other light elements (Be, B) on the main sequence companions of a number of X-ray novae. We conclude that one of the most promising mechanisms is the spallation of CNO elements on the surface of the companion induced by the neutron flux produced in the hot accretion flow onto the compact object. Direct production of the observed Li and its deposition onto the companion star seems less likely, mainly because of the possibility of its destruction in the production region itself and upon its impact onto the companion star's surface. We also compute the luminosities of the 2.2 MeV neutron capture line and also those of de-exitation of Be-7* (0.429 MeV), Li-7* (0.478 MeV) and Li-6* (3.561 MeV) expected in our model and examine the conditions under which they would result in fluxes observable with current or upcoming missions. C1 NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. RI Guessoum, Nidhal/C-3051-2013 NR 12 TC 1 Z9 1 U1 0 U2 1 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 415 EP 419 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000100 ER PT J AU Milne, PA Dixon, DD Leising, MD Kurfess, JD Leventhal, M Kinzer, RL Matz, SM Purcell, WR Smith, DM Tueller, J AF Milne, PA Dixon, DD Leising, MD Kurfess, JD Leventhal, M Kinzer, RL Matz, SM Purcell, WR Smith, DM Tueller, J TI OSSE observations of diffuse Galactic 511 keV emission SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAROMINA, ITALY DE gamma rays : observations; Galaxy : center; ISIW : general ID ANNIHILATION AB Following up on earlier observations, OSSE scanned the galactic center region during cycle 7. These observations, combined with cycle 6 and 7 observations of the galactic plane, have led to improved the maps of the 511 keV emission. Two fundamentally different mapping techniques show similar features, and further the arguments for both the existence of a positive latitude enhancement and for intense bulge emission. C1 USN, Res Lab, NRC Resident Res Associate, NRL, Washington, DC 20375 USA. Univ Calif Riverside, Inst Geophys & Planetary Phys, Riverside, CA 92521 USA. Clemson Univ, Clemson, SC 29631 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Northwestern Univ, Evanston, IL 60208 USA. Ball Aerosp, Boulder, CO 80306 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Milne, PA (reprint author), USN, Res Lab, NRC Resident Res Associate, NRL, Mail Code 7650, Washington, DC 20375 USA. RI Tueller, Jack/D-5334-2012 NR 3 TC 1 Z9 1 U1 0 U2 0 PU GORDON BREACH SCI PUBL LTD PI READING PA C/O STBS LTD, PO BOX 90, READING RG1 8JL, BERKS, ENGLAND SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 441 EP + PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000106 ER PT J AU Tatischeff, V Ramaty, R AF Tatischeff, V Ramaty, R TI Tracing low energy cosmic rays by nonthermal X-ray emission SO ASTROPHYSICAL LETTERS & COMMUNICATIONS LA English DT Article; Proceedings Paper CT 3rd Integral Workshop on the Extreme Universe CY SEP 14-18, 1998 CL TAORMINA, ITALY DE X-rays : theory; diffuse X-ray background; ROSAT; local hot bubble; gamma-rays : theory; COMPTEL AB We have developed in detail the theory of X-ray line and continuum production due to atomic interactions of accelerated ions. We apply our calculations to the 0.5-1 keV diffuse X-ray background observed with ROSAT. We show that a significant fraction of this background could be due to interactions of fast particles with the boundary shell of the local hot bubble. If the 0.5-1 keV non-thermal X-rays are produced by fast ions with a sufficiently hard energy spectrum, the gamma-ray line emission produced in the boundary shell of the local hot bubble could account for the reported COMPTEL observations of spectral features from a broad region towards the Galactic center. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 10 TC 1 Z9 1 U1 0 U2 0 PU GORDON BREACH PUBLISHING, TAYLOR & FRANCIS GROUP PI PHILADELPHIA PA 325 CHESTNUT ST, 8TH FL, PHILADELPHIA, PA 19106 USA SN 0888-6512 J9 ASTROPHYS LETT COMM JI Astrophys. Lett. Comm. PY 1999 VL 38 IS 1-6 BP 465 EP 468 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357NP UT WOS:000089508000112 ER PT J AU Rocca-Volmerange, B Fioc, M AF Rocca-Volmerange, B Fioc, M TI The star formation history as a function of type: Constraints from galaxy counts SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID HIGH-REDSHIFT GALAXIES; HUBBLE-DEEP-FIELD; LUMINOSITY FUNCTION; FAINT GALAXIES; EVOLUTION; ULTRAVIOLET; PHOTOMETRY; UNIVERSE; COLORS; MODEL AB Deep galaxy counts are among the best constraints on the cosmic star formation history (SFH) of galaxies. Using various tracers, the evolution of the star formation activity may now be followed on a wide range of redshifts (0 less than or equal to z less than or equal to 4) covering most of the history of the Universe. Two incompatible interpretations of the observations are currently competing. After applying star formation rate (SFR) conversion factors to the CFRS, H alpha or ISO samples, many authors conclude to a strong increase (similar or equal to a factor 10) of the SFR from z = 0 to z = 1. They also find some evidence for a peak at z similar or equal to 1 and for a rapid decrease at higher redshifts. On the other side, the Hawaii deep surveys favor only a mild increase between z = 0 and 1 (Cowie et al., 1996, 1999). In this paper, we tackle this problem from the point of view of the modelist of the spectral evolution of galaxies. To understand the reason for these discrepant interpretations, we consider three classes of galaxies: E/S0 ('early-type'); Sa-Sbc ('intermediate-type'); Sc-Sd, irregulars and bursting dwarfs ('late-type'). We use the new version of our evolutionary synthesis code, PEGASE (Fioc and Rocca-Volmerange, 2000, in preparation), which takes into account metallicity and dust effects. The main results are: i) Late-type galaxies contribute significantly to the local SFR, especially bursting dwarfs (Fioc and Rocca-Volmerange, 1999). Because of that, the cosmic SFR can not decrease by a factor 10 from z = 1 to 0. This is in agreement with Cowie et al., 1999's result. ii) The SFR of intermediate-type galaxies has strongly decreased since z = 1. Though the decrease is less than what find Lilly et al., 1996, this suggests that the CFRS and H alpha surveys are dominated by such bright early spirals. The limits in surface brightness and magnitudes of the observed samples may be the main reason for this selection. iii) The contribution of early-type galaxies increases rapidly from z =1 to their redshift of formation (greater than or equal to 2-3 for cosmological reasons). Their intense star formation rates at high-z give strong constraints on early ionization phases, primeval populations or metal enrichments. C1 Inst Astrophys, F-75014 Paris, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Rocca-Volmerange, B (reprint author), Inst Astrophys, 98bis Bd Arago, F-75014 Paris, France. NR 31 TC 3 Z9 3 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. PY 1999 VL 269 BP 233 EP 239 DI 10.1023/A:1017047604755 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 323VG UT WOS:000087585200018 ER PT J AU Kaiser, ME Bradley, LD Hutchings, JB Crenshaw, DM Kraemer, SB Ruiz, J Gull, TR Nelson, CH Weistrop, D AF Kaiser, ME Bradley, LD Hutchings, JB Crenshaw, DM Kraemer, SB Ruiz, J Gull, TR Nelson, CH Weistrop, D TI Kinematics and morphology of the resolved narrow line region in NGC 4151 SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID EMISSION; NGC-4151; NUCLEUS; RADIO AB A complement of HST narrow band images, STIS slitless and long-slit spectra have been employed to probe the morphology, kinematics, dynamics, and ionization structure of the near-nuclear region in NGC 4151. The images illustrate the inner biconical cloud distribution which exhibits recessional velocities relative to the nucleus to the NE and approaching velocities to the SW of the nucleus. The STIS spectra of the NLR map the velocity field from 1.2 kpc to within 13 pc (H-o = 75 km s(-1) Mpc(-1)) of the nucleus. We find evidence for at least two kinematic cloud populations. One is characterized by Low Velocities and Low Velocity Dispersions (LVLVD clouds: \ v \ < 400 km s(-1), and Delta v < 130 km s(-1)). These clouds extend through the NLR and may be gravitationally associated with the host galaxy. Another component is characterized by High Velocities and High Velocity Dispersions (HVHVD clouds: 400 < \ v \ less than or similar to 1700 km s(-1), Delta v greater than or equal to 130 km s(-1)). This set of clouds is located within 1.1 " (similar to 70 pc) of the nucleus and has radial velocities which are too high to be gravitational in origin, show no strong correlation with the knots in the radio jet, but are consistent with wind driven outflow. C1 Johns Hopkins Univ, Baltimore, MD 21218 USA. Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA. RP Kaiser, ME (reprint author), Johns Hopkins Univ, Baltimore, MD 21218 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 9 TC 1 Z9 1 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. PY 1999 VL 269 BP 431 EP 434 DI 10.1023/A:1017029921110 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 323VG UT WOS:000087585200036 ER PT J AU Fazio, GG Eisenhardt, P Huang, JS AF Fazio, GG Eisenhardt, P Huang, JS TI The Space Infrared Facility (SIRTF): A new probe for study of the birth and evolution of galaxies in the early Universe SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article AB The Space Infrared Telescope Facility (SIRTF) is the fourth and final element in NASA's family of orbiting "Great Observatories. SIRTF will offer order-of-magnitude improvements in capability over existing programs in the wavelength region between 3 and 180 microns. The combination of large-format detector arrays, with the intrinsic sensitivity of a cryogenic telescope, and the high sky visibility of a solar orbit, makes SIRTF an ideal instrument to carry out a number of very significant surveys to study the birth and evolution of galaxies in the early Universe. More than 75% of SIRTF's observing time will be available to the worldwide scientific community, with the first call for proposals in July, 2000. SIRTF will be launched in December 2001, with an anticipated lifetime of 5 years. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Fazio, GG (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. NR 3 TC 3 Z9 3 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. PY 1999 VL 269 BP 541 EP 548 DI 10.1023/A:1017035500154 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 323VG UT WOS:000087585200047 ER PT J AU Gurvits, LI Preston, RA Hirabayashi, H AF Gurvits, LI Preston, RA Hirabayashi, H TI Space VLBI as a tool for studying the Early Universe: First results and prospects SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article AB The technique of Very Long Baseline Interferometry (VLBI) occupies a special place among the tools of observing astronomy due to its unrivaled angular resolution. VLBI routinely allows for milliarcsecond-scale imaging at centimeter wavelengths with global arrays of radio telescopes. The ultimate development of the VLBI technique is Space VLBI, whereby one or more orbiting radio telescopes enable the baseline length limit imposed by the Earth diameter to be exceeded, and even higher angular resolution to be attained. The first dedicated Space VLBI mission, VSOP (VLBI Space Observatory Programme) began its scientific operation in 1997. We present VSOP results of the study of Active Galactic Nuclei (AGN) with milli- and sub-milliarcsecond angular resolution at observational wavelengths of 18 and 6 cm. These results, combined with the vast observational data base from various spectral domains, provide important clues about the nature of the most central regions of galaxies. We emphasize the early results of VSOP surveys which allow us to address the problem of the radio morphology and evolution of compact radio sources in AGN in the range of redshift from 4.5 to 0. We briefly discuss the prospect of space VLBI for the next century and its role in addressing the nature of the Early Universe. C1 VLBI Europe, Joint Inst, Dwingeloo, Netherlands. PN Lebedev Phys Inst, Ctr Astro Space, Moscow 117924, Russia. CALTECH, Jet Prop Lab, Pasadena, CA USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. RP Gurvits, LI (reprint author), VLBI Europe, Joint Inst, Dwingeloo, Netherlands. NR 8 TC 1 Z9 2 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. PY 1999 VL 269 BP 557 EP 562 DI 10.1023/A:1017039601062 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 323VG UT WOS:000087585200049 ER PT J AU Leisawitz, D Mather, JC Moseley, SH Zhang, XL AF Leisawitz, D Mather, JC Moseley, SH Zhang, XL TI The submillimeter probe of the evolution of cosmic structure (SPECS) SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID BACKGROUND EXPERIMENT SEARCH; FIRAS AB Following Mather et al. (1999) we describe a concept for a future space mission called SPECS, a spatial and spectral Michelson interferometer with Hubble Telescope-class angular resolution and sensitivity that operates in the far infrared and submillimeter spectral range. SPECS enables detailed studies of the physical conditions in high-redshift galaxies and has the potential to revolutionize our understanding of galaxy formation and evolution. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Leisawitz, D (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 10 TC 11 Z9 11 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. PY 1999 VL 269 BP 563 EP 567 DI 10.1023/A:1017091617901 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 323VG UT WOS:000087585200050 ER PT J AU Danks, AC AF Danks, AC TI The origin of QSO MgII lambda 2796 lines SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID INTERSTELLAR AB We have started a systematic spectroscopic survey of stars in the eta Carina nebula using the echelle mode of the Space Telescope Imaging Spectrograph (STIS). The Mg II lambda 2796/lambda 2803 lines seen in our R similar to 100000, spectra of the star CPD-59 degrees 2603 show a remarkable similarity with the intervening Mg II system seen in QSO absorption spectra. Such a comparison can shed light on the nature and origin of lines seen in QSO's. C1 Raytheon ITSS, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Danks, AC (reprint author), Raytheon ITSS, Code 683-0, Greenbelt, MD 20771 USA. EM danks@ambrose.gsfc.nasa.gov NR 7 TC 1 Z9 1 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PY 1999 VL 269 BP 639 EP 640 DI 10.1023/A:1017053431530 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 323VG UT WOS:000087585200066 ER PT J AU Hoover, RB Hoyle, F Wickramasinghe, NC Hoover, MJ Al-Mufti, S AF Hoover, RB Hoyle, F Wickramasinghe, NC Hoover, MJ Al-Mufti, S TI Diatoms on Earth, comets, Europa and in interstellar space SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID ORIGIN AB There exists a close correspondence between the measured infrared properties of diatoms and the infrared spectrum of interstellar dust as observed in the Trapezium nebula and toward the galactic center source GC-IRS 7. Diatoms and bacteria also exhibit an absorbance peak near 2200 Angstrom, which is found to agree with the observed ultraviolet absorbance properties of interstellar grains. We review the observational data and consider the known properties of diatoms and bacteria. It is suggested that these characteristics are consistent with the concept of a cosmic microbiological system in which these or similar microorganisms might exist on comets, Europa and in interstellar space. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Univ Coll, Dept Appl Math & Astron, Cardiff, S Glam, Wales. RP Hoover, RB (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. NR 65 TC 2 Z9 2 U1 0 U2 1 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. PY 1999 VL 268 IS 1-3 BP 197 EP 224 DI 10.1023/A:1002454431909 PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320UZ UT WOS:000087419900024 ER PT J AU Roman, NG AF Roman, NG TI The discovery of the chemical composition - Kinematics connection in the 1950's SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article AB This paper reviews the recognition that kinematic characteristics of stars are related to their spectroscopic appearance on low and intermediate dispersion spectra. These differences result from the differences in the abundances of metals as determined from high dispersion spectra. Presumably, these abundance differences reflect differences in age. The high-velocity carbon stars share the molecular peculiarities of the high-velocity oxygen giants but, because of the greater strength of the bands of carbon-containing molecules, exhibit them to a greater degree. C1 Hughes STX, NASA, Astron Data Ctr, Greenbelt, MD USA. RP Roman, NG (reprint author), Hughes STX, NASA, Astron Data Ctr, Greenbelt, MD USA. NR 28 TC 0 Z9 0 U1 1 U2 1 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. PY 1999 VL 267 IS 1-4 BP 37 EP 44 DI 10.1023/A:1002715507043 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 320UY UT WOS:000087419800006 ER PT J AU Davidson, JA AF Davidson, JA TI Stratospheric Observatory For Infrared Astronomy (SOFIA) SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Workshop on Ulraluminous Galaxies - Monsters of Babies CY SEP 20-26, 1998 CL BAVARIA, GERMANY SP Max Planck Inst Extraterestr Physik C1 NASA, Univ Space Res Assoc, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Davidson, JA (reprint author), NASA, Univ Space Res Assoc, Ames Res Ctr, MS T3B, Moffett Field, CA 94035 USA. NR 6 TC 1 Z9 1 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. PY 1999 VL 266 IS 1-2 BP 35 EP 40 DI 10.1023/A:1002672909029 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 312MM UT WOS:000086947100006 ER PT J AU Fischer, J Luhman, ML Satyapal, S Greenhouse, MA Stacey, GJ Bradford, CM Lord, SD Brauher, JR Unger, SJ Clegg, PE Smith, HA Melnick, G Colbert, JW Malkan, MA Spinoglio, L Cox, P Harvey, V Suter, JP Strelnitski, V AF Fischer, J Luhman, ML Satyapal, S Greenhouse, MA Stacey, GJ Bradford, CM Lord, SD Brauher, JR Unger, SJ Clegg, PE Smith, HA Melnick, G Colbert, JW Malkan, MA Spinoglio, L Cox, P Harvey, V Suter, JP Strelnitski, V TI ISO FAR-IR spectroscopy of IR-bright galaxies and ULIRGs SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Workshop on Ulraluminous Galaxies - Monsters of Babies CY SEP 20-26, 1998 CL BAVARIA, GERMANY SP Max Planck Inst Extraterestr Physik DE infrared-bright galaxies; ultraluminous galaxies; far-infrared spectra; starbursts; interstellar medium ID LONG-WAVELENGTH SPECTROMETER; NGC-1068 AB Based on far-infrared spectroscopy of a small sample of nearby infrared-bright and ultraluminous infrared galaxies (ULIRGs) with the ISO Long Wavelength Spectrometer(1) we find a dramatic progression in ionic/atomic fine-structure emission line and molecular/atomic absorption line characteristics in these galaxies extending from strong [O III]52,88 mu m and [N III]57 mu m line emission to detection of only faint [C II]158 mu m line emission from gas in photodissociation regions in the ULIRGs. The molecular absorption spectra show varying excitation as well, extending from galaxies in which the molecular population mainly occupies the ground state to galaxies in which there is significant population in higher levels. In the case of the prototypical ULIRG, the merger galaxy Arp 220, the spectrum is dominated by absorption lines of OH, H2O, CH, and [O I]. Low [O III]88 mu m line flux relative to the integrated far-infrared flux correlates with low excitation and does not appear to be due to far-infrared extinction or to density effects. A progression toward soft radiation fields or very dusty H II regions may explain these effects. C1 USN, Res Lab, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. CALTECH, IPAC, Pasadena, CA 91125 USA. Univ London Queen Mary & Westfield Coll, London E1 4NS, England. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90024 USA. CNR, Ist Fis Spazio Interplanetario, Rome, Italy. Inst Astron Spatiale, Orsay, France. Maria Mitchell Observ, Nantucket, MA USA. RP Fischer, J (reprint author), USN, Res Lab, Washington, DC 20375 USA. OI Spinoglio, Luigi/0000-0001-8840-1551 NR 21 TC 41 Z9 41 U1 0 U2 1 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. PY 1999 VL 266 IS 1-2 BP 91 EP 98 DI 10.1023/A:1002641429502 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 312MM UT WOS:000086947100015 ER PT J AU Egami, E Soifer, BT Neugebauer, G Matthews, K Becklin, EE Weinberger, AJ Ressler, M Werner, MW AF Egami, E Soifer, BT Neugebauer, G Matthews, K Becklin, EE Weinberger, AJ Ressler, M Werner, MW TI Keck mid-IR high-resolution imaging of ARP 220 SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Workshop on Ulraluminous Galaxies - Monsters of Babies CY SEP 20-26, 1998 CL BAVARIA, GERMANY SP Max Planck Inst Extraterestr Physik C1 CALTECH, Downs Lab Phys 320 47, Pasadena, CA 91106 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Egami, E (reprint author), CALTECH, Downs Lab Phys 320 47, Pasadena, CA 91106 USA. NR 5 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. PY 1999 VL 266 IS 1-2 BP 109 EP 111 DI 10.1023/A:1002697514481 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 312MM UT WOS:000086947100018 ER PT J AU Borne, KD Bushouse, H Colina, L Lucas, RA Baker, A Clements, D Lawrence, A Oliver, S Rowan-Robinson, M AF Borne, KD Bushouse, H Colina, L Lucas, RA Baker, A Clements, D Lawrence, A Oliver, S Rowan-Robinson, M TI A morphological classification scheme for ULIRGs - Evidencde for multiple mergers SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Workshop on Ultraluminous Galaxies - Monsters of Babies CY SEP 20-26, 1998 CL BAVARIA, GERMANY SP Max Planck Inst Extraterr Phys ID ULTRALUMINOUS INFRARED GALAXIES; ORIGIN C1 NASA, Raytheon Informat Technol & Sci Serv, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. STScI, Baltimore, MD USA. Cardiff Univ, Cardiff, S Glam, Wales. Univ Edinburgh, Inst Astron, Edinburgh EH8 9YL, Midlothian, Scotland. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London, England. RP Borne, KD (reprint author), NASA, Raytheon Informat Technol & Sci Serv, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 10 TC 28 Z9 28 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PY 1999 VL 266 IS 1-2 BP 137 EP 142 DI 10.1023/A:1002657900368 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 312MM UT WOS:000086947100023 ER PT J AU Arribas, S Colina, L Borne, K AF Arribas, S Colina, L Borne, K TI Two-dimensional optical spectroscopy of ULIRG's: Comparison with HST imaging SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Workshop on Ulraluminous Galaxies - Monsters of Babies CY SEP 20-26, 1998 CL BAVARIA, GERMANY SP Max Planck Inst Extraterestr Physik AB We present preliminary results of our programme aimed at the study of a sample of ULIRGs on the basis of two-dimensional (integral field) optical spectroscopy and multi-frequency high spatial resolution HST imaging. In particular, we show here results on Mrk 273 and IRAS 12112+0305 recently obtained with the INTEGRAL system at the 4.2 m WHT. A brief comparison with the HST images is also made. C1 Inst Astrofis Canarias, Tenerife 38200, Spain. Space Telescope Sci Inst, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Arribas, S (reprint author), Inst Astrofis Canarias, Tenerife 38200, Spain. RI Arribas, Santiago/F-9277-2015 OI Arribas, Santiago/0000-0001-7997-1640 NR 3 TC 2 Z9 2 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. PY 1999 VL 266 IS 1-2 BP 143 EP 148 DI 10.1023/A:1002610017207 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 312MM UT WOS:000086947100024 ER PT J AU Sonneborn, G Jenkins, EB Tripp, T Wozniak, P Vidal-Madjar, A Ferlet, R Sofia, UJ AF Sonneborn, G Jenkins, EB Tripp, T Wozniak, P Vidal-Madjar, A Ferlet, R Sofia, UJ TI New observations of galactic deuterium SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Colloquium on Galaxy Evolution - Connecting the Distant Universe with the Local Fossil Record CY SEP 21-25, 1998 CL OBSERVATOIRR PARIR-MEUDON, PARIS, FRANCE SP Minist Educ Natl Rech, Minist Affaires Etrangeres, Canada France HI Telescope Corp, CNRS SDU, GdR Galacies Structure Interne, Dept Phys Etoiles Galaxies DASGAL, Inst Astrophys Paris, Bureau Longitudes HO OBSERVATOIRR PARIR-MEUDON ID INTERSTELLAR-MEDIUM C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Inst Astrophys, F-75014 Paris, France. Whitman Coll, Dept Astron, Walla Walla, WA 99362 USA. RP Sonneborn, G (reprint author), NASA, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. RI Sonneborn, George/D-5255-2012; Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 4 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. PY 1999 VL 265 IS 1-4 BP 55 EP 56 DI 10.1023/A:1002108723340 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 308NG UT WOS:000086718900010 ER PT J AU Ramaty, R Lingenfelter, RE AF Ramaty, R Lingenfelter, RE TI LiBeB energetics and cosmic ray origin SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Colloquium on Galaxy Evolution - Connecting the Distant Universe with the Local Fossil Record CY SEP 21-25, 1998 CL OBSERVATOIRR PARIR-MEUDON, PARIS, FRANCE SP Minist Educ Natl Rech, Minist Affaires Etrangeres, Canada France HI Telescope Corp, CNRS SDU, GdR Galacies Structure Interne, Dept Phys Etoiles Galaxies DASGAL, Inst Astrophys Paris, Bureau Longitudes HO OBSERVATOIRR PARIR-MEUDON ID LIGHT-ELEMENTS; SUPERNOVA-REMNANTS; EARLY GALAXY; ACCELERATION; LINES; NUCLEOSYNTHESIS; EVOLUTION; STARS; GAS AB Three different models have been proposed for LiBeB production by cosmic rays: the CRI model in which the cosmic rays are accelerated out of an ISM of solar composition scaled with metallicity; the CRS model in which cosmic rays with composition similar to that of the current epoch cosmic rays are accelerated out of fresh supernova ejecta; and the LECR model in which a distinct low energy component coexists with the postulated cosmic rays of the CRI model. These models are usually distinguished by their predictions concerning the evolution of the Be and B abundances. Here we emphasize the energetics which favor the CRS model. This model is also favored by observations showing that the bulk (80 to 90%) of all supernovae occur in hot, low density superbubbles, where supernova shocks can accelerate the cosmic rays from supernova ejecta enriched matter. C1 NASA, GSFC, Greenbelt, MD 20771 USA. Univ Calif San Diego, La Jolla, CA 92093 USA. RP Ramaty, R (reprint author), NASA, GSFC, Greenbelt, MD 20771 USA. NR 24 TC 1 Z9 1 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. PY 1999 VL 265 IS 1-4 BP 71 EP 76 DI 10.1023/A:1002185328791 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 308NG UT WOS:000086718900013 ER PT J AU Cavallo, RM AF Cavallo, RM TI Aluminum abundances on the red giant branch: Testing helium mixing as a second parameter SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Colloquium on Galaxy Evolution - Connecting the Distant Universe with the Local Fossil Record CY SEP 21-25, 1998 CL OBSERVATOIRR PARIR-MEUDON, PARIS, FRANCE SP Minist Educ Natl Rech, Minist Affaires Etrangeres, Canada France HI Telescope Corp, CNRS SDU, GdR Galacies Structure Interne, Dept Phys Etoiles Galaxies DASGAL, Inst Astrophys Paris, Bureau Longitudes HO OBSERVATOIRR PARIR-MEUDON ID OXYGEN ABUNDANCES; HALO GIANTS; M13 C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Cavallo, RM (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 10 TC 0 Z9 0 U1 0 U2 1 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. PY 1999 VL 265 IS 1-4 BP 191 EP 192 DI 10.1023/A:1002155409652 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 308NG UT WOS:000086718900036 ER PT J AU Rocca-Volmerange, B Fioc, M AF Rocca-Volmerange, B Fioc, M TI Star formation histories from faint galaxy counts SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Colloquium on Galaxy Evolution - Connecting the Distant Universe with the Local Fossil Record CY SEP 21-25, 1998 CL OBSERVATOIRR PARIR-MEUDON, PARIS, FRANCE SP Minist Educ Natl Rech, Minist Affaires Etrangeres, Canada France HI Telescope Corp, CNRS SDU, GdR Galacies Structure Interne, Dept Phys Etoiles Galaxies DASGAL, Inst Astrophys Paris, Bureau Longitudes HO OBSERVATOIRR PARIR-MEUDON ID HUBBLE-DEEP-FIELD; HIGH-REDSHIFT GALAXIES; LUMINOSITY FUNCTION; SPECTRAL EVOLUTION; MODEL AB Multispectral Faint galaxy counts, including the deepest Hubble Deep Field, are interpreted with the help of our evolution model PEGASE (Fioc and Rocca-Volmerange, 1997). The best fits correspond to galaxy formations at high redshifts, a pure luminosity evolution and classical luminosity functions. The adopted cosmology is a flat universe with the matter density parameter Omega(M) = 0.3 and a cosmological constant Omega(Lambda) = 0.7. A solution with Omega(M) = 0.01 (open universe) is also acceptable. But a flat universe with Omega(M) = 1 is clearly excluded. The star formation histories for galaxy types are derived from scenarios of evolution. The comparison with results already published in the litterature, arises puzzling problems needing a further analysis of star formation tracers, specifically for bright galaxies. C1 Inst Astrophys, F-75014 Paris, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Rocca-Volmerange, B (reprint author), Inst Astrophys, 98bis Bd Arago, F-75014 Paris, France. NR 17 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. PY 1999 VL 265 IS 1-4 BP 507 EP 511 DI 10.1023/A:1002143623649 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 308NG UT WOS:000086718900109 ER PT J AU Heap, S Brown, T Lanz, T Yi, S AF Heap, S Brown, T Lanz, T Yi, S TI Uv spectroscopic dating of stars and galaxies SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Colloquium on Galaxy Evolution - Connecting the Distant Universe with the Local Fossil Record CY SEP 21-25, 1998 CL OBSERVATOIRR PARIR-MEUDON, PARIS, FRANCE SP Minist Educ Natl Rech, Minist Affaires Etrangeres, Canada France HI Telescope Corp, CNRS SDU, GdR Galacies Structure Interne, Dept Phys Etoiles Galaxies DASGAL, Inst Astrophys Paris, Bureau Longitudes HO OBSERVATOIRR PARIR-MEUDON C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, Pasadena, CA 91125 USA. RP Heap, S (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI heap, sara/E-2237-2012; OI Brown, Thomas/0000-0002-1793-9968 NR 9 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. PY 1999 VL 265 IS 1-4 BP 531 EP 532 DI 10.1023/A:1002199725466 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 308NG UT WOS:000086718900112 ER PT B AU Teplitz, HI Gardner, JP Malumuth, EM Heap, SR AF Teplitz, HI Gardner, JP Malumuth, EM Heap, SR BE Bicay, M Beichman, CA Cutri, RM Madore, BF TI A parallel mode survey with NICMOS SO ASTROPHYSICS WITH INFRARED SURVEYS: A PRELUDE TO SIRTF SE Astronomical Society of the Pacific Conference Series LA English DT Proceedings Paper CT Conference on Astrophysics with Infrared Surveys - A Prelude to SIRTF CY JUN 22-24, 1998 CL CALIFORNIA INST TECHNOL, PASADENA, CA SP NASA Off Space Sci, SIRTR Sci Ctr, Infrared Processing & Anal Ctr, Caltech Off Public Events, SIRTF Project Off JPL, Lockheed Martin Missiles & Space, Ball Aerosp Technol Corp HO CALIFORNIA INST TECHNOL ID GALAXIES AB We present the initial results of our analysis of the NICMOS Parallel Survey. We have classified galaxies in the Camera 2 sample by morphological type to H1.6 < 23 We find relatively fewer irregular galaxies compared to an I-band sample from the Hubble Deep Field, which we attribute to their blue color, rather than to morphological K-corrections. We conclude that the irregulars are intrinsically faint blue galaxies at z<1. We also present typical examples of emission-line galaxies detected in the NICMOS Parallel Grism Survey with G141. We infer that these object are at z > 1, and are star-forming galaxies with star formation rates similar to 40 M./year. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. RI heap, sara/E-2237-2012 NR 11 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-001-3 J9 ASTR SOC P PY 1999 VL 177 BP 64 EP 67 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN89F UT WOS:000083362400008 ER PT B AU Xu, C Hacking, PB Fang, F Shupe, DL Lonsdale, CJ Lu, NYY Helou, G Stacey, GJ Ashby, MLN AF Xu, C Hacking, PB Fang, F Shupe, DL Lonsdale, CJ Lu, NYY Helou, G Stacey, GJ Ashby, MLN BE Bicay, M Beichman, CA Cutri, RM Madore, BF TI Source counts and redshift distributions of deep MIR surveys SO ASTROPHYSICS WITH INFRARED SURVEYS: A PRELUDE TO SIRTF SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Astrophysics with Infrared Surveys - A Prelude to SIRTF CY JUN 22-24, 1998 CL CALIFORNIA INST TECHNOL, PASADENA, CA SP NASA Off Space Sci, SIRTR Sci Ctr, Infrared Processing & Anal Ctr, Caltech Off Public Events, SIRTF Project Off JPL, Lockheed Martin Missiles & Space, Ball Aerosp Technol Corp HO CALIFORNIA INST TECHNOL AB A new IR SED model incorporating the newest ISO results on the mid-infrared spectral-energy-distributions of galaxies is developed. Applying the SED model to a large sample of MIR selected galaxies (Shupe ef al. 1998), K-corrections for deep surveys at various MIR wavelengths are calculated. Significant dips and bumps, due primarily to the prominent MIR emission features, are predicted on the number counts and redshift distributions based on the new results on K-corrections. In particular, the bump at z similar to 2 an the redshift distribution of the WIRE 25 mu m survey suggests that deep surveys at similar to 25 mu m will detect many galaxies with high redshifts (z greater than or similar to 2). C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. RP Xu, C (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, 100-22, Pasadena, CA 91125 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-001-3 J9 ASTR SOC P PY 1999 VL 177 BP 104 EP 107 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN89F UT WOS:000083362400015 ER PT B AU Satyapal, S Luhman, ML Fischer, J Colbert, J Malkan, MA Greenhouse, MA Lord, SD Smith, HA Stacey, GJ Unger, SJ AF Satyapal, S Luhman, ML Fischer, J Colbert, J Malkan, MA Greenhouse, MA Lord, SD Smith, HA Stacey, GJ Unger, SJ BE Bicay, M Beichman, CA Cutri, RM Madore, BF TI A multi-wavelength infrared study of IR bright galaxies: The impact on SIRTF SO ASTROPHYSICS WITH INFRARED SURVEYS: A PRELUDE TO SIRTF SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Astrophysics with Infrared Surveys - A Prelude to SIRTF CY JUN 22-24, 1998 CL CALIFORNIA INST TECHNOL, PASADENA, CA SP NASA Off Space Sci, SIRTR Sci Ctr, Infrared Processing & Anal Ctr, Caltech Off Public Events, SIRTF Project Off JPL, Lockheed Martin Missiles & Space, Ball Aerosp Technol Corp HO CALIFORNIA INST TECHNOL AB As examples of colliding galaxies, nearby luminous and ultraluminous infrared galaxies (LIGs and ULIGs, respectively) likely rep resent local analogs of high redshift protogalaxies. Therefore, recent ISO mid- and far-infrared spectra of LIGs and ULIGs may provide important clues regarding the spectral appearance of protogalaxies over the wavelength range of peak flux density. In this study, we compare our ISO Long Wavelength Spectrometer spectra of a number of LIGs and ULIGs with complementary ground-bas ed and ISO data in the near- and midinfrared. In each source, we address the self-consistent behavior of all infrared lines. Based on this comparison, we discuss which spectroscopic features provide the most useful diagnostics of protogalaxies, and, in particular, those that fall within the SIRTF wavelength range. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Satyapal, S (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-001-3 J9 ASTR SOC P PY 1999 VL 177 BP 161 EP 166 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN89F UT WOS:000083362400024 ER PT B AU Borne, KD Bushouse, H Colina, L Lucas, RA Baker, A Clements, D Lawrence, A Oliver, S Rowan-Robinson, M AF Borne, KD Bushouse, H Colina, L Lucas, RA Baker, A Clements, D Lawrence, A Oliver, S Rowan-Robinson, M BE Bicay, M Beichman, CA Cutri, RM Madore, BF TI NICMOS and WFPC2 imaging of ultraluminous galaxies SO ASTROPHYSICS WITH INFRARED SURVEYS: A PRELUDE TO SIRTF SE Astronomical Society of the Pacific Conference Series LA English DT Proceedings Paper CT Conference on Astrophysics with Infrared Surveys - A Prelude to SIRTF CY JUN 22-24, 1998 CL CALIFORNIA INST TECHNOL, PASADENA, CA SP NASA Off Space Sci, SIRTR Sci Ctr, Infrared Processing & Anal Ctr, Caltech Off Public Events, SIRTF Project Off JPL, Lockheed Martin Missiles & Space, Ball Aerosp Technol Corp HO CALIFORNIA INST TECHNOL ID INFRARED GALAXIES; IRAS GALAXIES AB HST is used to study the power sources and the interaction-induced tidal disturbances within the most luminous galaxies in the local universe - the Ultra-Luminous IR Galaxies (ULIRGs) - through the use of I-band images with WFPC2 and H-band images with NICMOS. C1 NASA, Goddard Space Flight Ctr, Raytheon STX Corp, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, Raytheon STX Corp, Greenbelt, MD 20771 USA. NR 13 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-001-3 J9 ASTR SOC P PY 1999 VL 177 BP 167 EP 170 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN89F UT WOS:000083362400025 ER PT B AU Chan, KW Roellig, TL Onaka, T Yamamura, I Tanabe, T AF Chan, KW Roellig, TL Onaka, T Yamamura, I Tanabe, T BE Bicay, M Beichman, CA Cutri, RM Madore, BF TI The nature of the mid-infrared background radiation in the Galactic Center and bulge regions from the IRTS observations SO ASTROPHYSICS WITH INFRARED SURVEYS: A PRELUDE TO SIRTF SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Astrophysics with Infrared Surveys - A Prelude to SIRTF CY JUN 22-24, 1998 CL CALIFORNIA INST TECHNOL, PASADENA, CA SP NASA Off Space Sci, SIRTR Sci Ctr, Infrared Processing & Anal Ctr, Caltech Off Public Events, SIRTF Project Off JPL, Lockheed Martin Missiles & Space, Ball Aerosp Technol Corp HO CALIFORNIA INST TECHNOL ID AGB STARS; EMISSION; DUST AB Using the Mid-Infrared Spectrometer (MIRS) on board the Infrared Telescope in Space we obtained the 4.5-11.7 Cam spectra of the stellar populations and diffuse interstellar medium in the Galactic center and bulge regions. At all the positions we selected in the Galactic center region, the MIRS detected the unidentified infrared features at 6.2, 7.7, 8.6, and 11.3 mu m. On average, the integrated NIRS in-band (7.1-11.7 mu m) flux contributes similar to 75% Of the integrated IRAS 12 mu m in-band flux at the selected positions. On the other hand, the MIRS spectra in the high latitudes of the Galactic bulge are similar to the spectra of those oxygen-rich evolved stars with high mass-loss rates detected by IRAS. One likely interpretation is that this background emission arises predominantly from those stars with very low luminosities that have not been detected by IRAS. The age for such low-luminosity evolved stars could be 15 Gyr, and these faint AGE stars could be the dominant source of the interstellar medium in the central region of the Galaxy. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Chan, KW (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. NR 23 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-001-3 J9 ASTR SOC P PY 1999 VL 177 BP 326 EP 331 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN89F UT WOS:000083362400049 ER PT B AU Hacking, P Lonsdale, C Gautier, T Herter, T Shupe, D Stacey, G Fang, F Xu, C Graf, P Werner, M Soifer, B Moseley, H Houck, J AF Hacking, P Lonsdale, C Gautier, T Herter, T Shupe, D Stacey, G Fang, F Xu, C Graf, P Werner, M Soifer, B Moseley, H Houck, J BE Bicay, M Beichman, CA Cutri, RM Madore, BF TI The Wide-Field Infrared Explorer (WIRE) mission SO ASTROPHYSICS WITH INFRARED SURVEYS: A PRELUDE TO SIRTF SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Astrophysics with Infrared Surveys - A Prelude to SIRTF CY JUN 22-24, 1998 CL CALIFORNIA INST TECHNOL, PASADENA, CA SP NASA Off Space Sci, SIRTR Sci Ctr, Infrared Processing & Anal Ctr, Caltech Off Public Events, SIRTF Project Off JPL, Lockheed Martin Missiles & Space, Ball Aerosp Technol Corp HO CALIFORNIA INST TECHNOL ID LUMINOSITY FUNCTION AB The Wide-Field Infrared Explorer (WIRE) was selected in 1994 as NASA's 5th Small Explorer mission. WIRE's primary science objective is to conduct a deep infrared survey to investigate the evolution of starburst galaxies and search for protogalaxies at high redshifts. WIRE will survey similar to 1000 square degrees at 12 and 25 mu at 200-2000 times fainter flux levels than the IRAS Faint Source Catalog (0.1-1.0 mJy depending upon wavelength and depth of coverage). We anticipate that WIRE will detect about 100,000 starburst galaxies, at typical redshifts of 0.5, and potentially hundreds of protogalaxies at much higher redshifts. The WIRE instrument consists of a 30-cm telescope in a dual-stage, solid-hydrogen cryostat, and utilizes two 128x128 format Si:As BIB detectors. Science investigations along the Galactic and ecliptic planes will be conducted through NASA's Associate Investigator Program. C1 Vanguard Res Inc, JPL, Pasadena, CA USA. RP Hacking, P (reprint author), Vanguard Res Inc, JPL, Pasadena, CA USA. RI Moseley, Harvey/D-5069-2012 NR 21 TC 12 Z9 12 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-001-3 J9 ASTR SOC P PY 1999 VL 177 BP 409 EP 420 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN89F UT WOS:000083362400064 ER PT B AU Werner, M AF Werner, M BE Bicay, M Beichman, CA Cutri, RM Madore, BF TI Scientific opportunities with SIRTF SO ASTROPHYSICS WITH INFRARED SURVEYS: A PRELUDE TO SIRTF SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Astrophysics with Infrared Surveys - A Prelude to SIRTF CY JUN 22-24, 1998 CL CALIFORNIA INST TECHNOL, PASADENA, CA SP NASA Off Space Sci, SIRTR Sci Ctr, Infrared Processing & Anal Ctr, Caltech Off Public Events, SIRTF Project Off JPL, Lockheed Martin Missiles & Space, Ball Aerosp Technol Corp HO CALIFORNIA INST TECHNOL ID TELESCOPE-FACILITY SIRTF; SPACE; GALAXIES AB This paper summarizes the scientific opportunities made available by SIRTF - the Space Infrared Telescope Facility. SIRTF will be a cryogenically-cooled space telescope instrumented with large-format, state of the art monolithic infrared detector arrays. SIRTF will complete NASA's family of Great Observatories and also serve as the first major scientific and technical step in the Origins program. It will be launched in 2001, carrying a complement of imaging and spectroscopic instrumentation. More than 75% of the observing time on SIRTF will be available to the general scientific community. In the context of this meeting on astrophysics with infrared surveys, SIRTF provides both an opportunity to follow up on phenomena identified in earlier surveys and the capability to extend these surveys to greater depth. SIRTF's scientific strategy accommodates the implementation of surveys early in the mission through a community-based Legacy Science program. The first opportunity for the general community to propose for observing time on SIRTF will come with the first call for Legacy Science proposals, to be released in July, 2000. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Werner, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 21 TC 1 Z9 1 U1 1 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-001-3 J9 ASTR SOC P PY 1999 VL 177 BP 451 EP 461 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN89F UT WOS:000083362400070 ER PT J AU Bhatia, AK Doschek, GA AF Bhatia, AK Doschek, GA TI Atomic data and spectral line intensities for Ni XVI SO ATOMIC DATA AND NUCLEAR DATA TABLES LA English DT Article ID HIGHLY IONIZED NICKEL; AL-LIKE IONS; BEAM-FOIL; CROSS-SECTIONS; FE; TRANSITIONS; EXCITATION; VII; IX AB Electron impact collision strengths and spontaneous radiative decay rates are calculated for Ni XVI. The data pertain to the 40 levels of the configurations 3s(2)3p, 3s3p(2), 3s(2)3d, 3p(3), and 3s3p3d. Collision strengths are calculated at five incident electron energies: 10.0, 20.0, 30.0, 30.0, and 50.0 Ry. Relative spectral line intensities are calculated for all astrophysically important transitions. These are obtained by computing the excitation rate coefficients (cm(3) s(-1)), that is, the collision strengths integrated over a Maxwellian electron distribution, and then solving the equations of detailed balance for the populations of the 40 energy levels, assuming a collisional excitation model and an electron temperature of 2.51 x 10(6) K. This temperature is typical for Ni XVI when formed in equilibrium by collisional ionization and recombination. With the excitation rate coefficients and the radiative decay rates, level populations are computed for several electron densities and are given in this paper. We also investigate the effects of proton excitation and solar radiative excitation on the level populations and line intensities. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RP Bhatia, AK (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. NR 33 TC 12 Z9 12 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0092-640X J9 ATOM DATA NUCL DATA JI Atom. Data Nucl. Data Tables PD JAN PY 1999 VL 71 IS 1 BP 69 EP 102 DI 10.1006/adnd.1998.0800 PG 34 WC Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Physics GA 182PL UT WOS:000079507300003 ER PT B AU Comstock, JR Derks, PL AF Comstock, JR Derks, PL BE Scerbo, MW Mouloua, M TI Performance effects of display incongruity in a digital and analog clock reading task SO AUTOMATION TECHNOLOGY AND HUMAN PERFORMANCE: CURRENT RESEARCH AND TRENDS LA English DT Proceedings Paper CT 3rd Conference on Automation Technology and Human Performance CY MAR 25-28, 1998 CL NORFOLK, VA SP Dept Psychol, Old Dominion Univ, Coll Sci, Old Dominion Univ, NASA Langley Res Ctr, Off Naval Res, Human Factors & Ergonom Soc, Tidewater Chapter C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Comstock, JR (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LAWRENCE ERLBAUM ASSOC PUBL PI MAHWAH PA 10 INDUSTRIAL AVE, MAHWAH, NJ 07430 USA BN 0-8058-3135-5 PY 1999 BP 231 EP 234 PG 4 WC Computer Science, Cybernetics; Engineering, Industrial; Ergonomics; Psychology SC Computer Science; Engineering; Psychology GA BL92Z UT WOS:000077172900041 ER PT B AU Schutte, PC Trujillo, AC AF Schutte, PC Trujillo, AC BE Scerbo, MW Mouloua, M TI Pilot fault management performance: An evaluation of assistance SO AUTOMATION TECHNOLOGY AND HUMAN PERFORMANCE: CURRENT RESEARCH AND TRENDS LA English DT Proceedings Paper CT 3rd Conference on Automation Technology and Human Performance CY MAR 25-28, 1998 CL NORFOLK, VA SP Dept Psychol, Old Dominion Univ, Coll Sci, Old Dominion Univ, NASA Langley Res Ctr, Off Naval Res, Human Factors & Ergonom Soc, Tidewater Chapter C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Schutte, PC (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU LAWRENCE ERLBAUM ASSOC PUBL PI MAHWAH PA 10 INDUSTRIAL AVE, MAHWAH, NJ 07430 USA BN 0-8058-3135-5 PY 1999 BP 240 EP 245 PG 6 WC Computer Science, Cybernetics; Engineering, Industrial; Ergonomics; Psychology SC Computer Science; Engineering; Psychology GA BL92Z UT WOS:000077172900043 ER PT B AU Gifford, RB AF Gifford, RB BE Scerbo, MW Mouloua, M TI The necessity of the pilot SO AUTOMATION TECHNOLOGY AND HUMAN PERFORMANCE: CURRENT RESEARCH AND TRENDS LA English DT Meeting Abstract CT 3rd Conference on Automation Technology and Human Performance CY MAR 25-28, 1998 CL NORFOLK, VA SP Dept Psychol, Old Dominion Univ, Coll Sci, Old Dominion Univ, NASA Langley Res Ctr, Off Naval Res, Human Factors & Ergonom Soc, Tidewater Chapter C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LAWRENCE ERLBAUM ASSOC PUBL PI MAHWAH PA 10 INDUSTRIAL AVE, MAHWAH, NJ 07430 USA BN 0-8058-3135-5 PY 1999 BP 318 EP 318 PG 1 WC Computer Science, Cybernetics; Engineering, Industrial; Ergonomics; Psychology SC Computer Science; Engineering; Psychology GA BL92Z UT WOS:000077172900062 ER PT B AU Schutte, PC AF Schutte, PC BE Scerbo, MW Mouloua, M TI Why humans are necessary on the flight deck: Supporting the requisite role of the pilot SO AUTOMATION TECHNOLOGY AND HUMAN PERFORMANCE: CURRENT RESEARCH AND TRENDS LA English DT Meeting Abstract CT 3rd Conference on Automation Technology and Human Performance CY MAR 25-28, 1998 CL NORFOLK, VA SP Dept Psychol, Old Dominion Univ, Coll Sci, Old Dominion Univ, NASA Langley Res Ctr, Off Naval Res, Human Factors & Ergonom Soc, Tidewater Chapter C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LAWRENCE ERLBAUM ASSOC PUBL PI MAHWAH PA 10 INDUSTRIAL AVE, MAHWAH, NJ 07430 USA BN 0-8058-3135-5 PY 1999 BP 318 EP 318 PG 1 WC Computer Science, Cybernetics; Engineering, Industrial; Ergonomics; Psychology SC Computer Science; Engineering; Psychology GA BL92Z UT WOS:000077172900061 ER PT J AU Dearborn, AS Ertl, AC Jackson, CGR Barnes, PR Breckler, JL Greenleaf, JE AF Dearborn, AS Ertl, AC Jackson, CGR Barnes, PR Breckler, JL Greenleaf, JE TI Effect of glucose-water ingestion on exercise thermoregulation in men dehydrated after water immersion SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE hyperglycemia; temperature regulation; dehydration ID TEMPERATURE REGULATION; PROLONGED EXERCISE; PHYSICAL EXERCISE; PLASMA-VOLUME; BLOOD-VOLUME; DOGS; HYPOHYDRATION; OSMOLALITY; HUMANS; STRESS AB Background: The influence of non-ionic osmols on thermoregulation is unclear. Hypothesis: Hyperglycemia will attenuate the rise in exercise core temperature. Methods: Dehydrated by 4-h of water immersion (34.5 degrees C) to the neck, 6 men, (35 +/- SD 7 yr) participated in each of three trials where 2.0 g.kg(-1) body wt of oral glucose (33.8% weight per volume) was consumed followed by 80 min supine rest (Glu/Rest), or 70 min supine cycle exercise at 62.8% +/- SE 0.5% (1.97 +/- 0.02 L.min(-1)) peak O-2 uptake, followed by 10 min supine recovery with prior (Glu/Ex) or without glucose (No Glu/Ex) ingestion. Blood samples were taken periodically for measurement of Hb, Hct, Na+, K+, Osm, and glucose; mean skin ((T) over bar sk) and rectal (Tre) temperatures, and sweating rate (resistance hygrometry) and skin blood velocity (laser Doppler) were measured intermittently. Results: Mean percent changes in plasma volume (p < 0.05) for the exercise trials were not different: -12.3 +/- 2.2% (No Glu/Ex) and -12.1 +/- 2.1%(Glu/Ex). Mean (+/-SE) pre-exercise plasma [glucose] for Glu/Ex was higher than that of No Glu/Ex (108.4 +/- 3.9 vs. 85.6 +/- 1.6 mg.dL(-1), respectively, p < 0.05). Glu/Ex vs. No Glu/Ex data, respectively, at the end of exercise indicated that: Tre wa lower by 0.4 degrees C (38.2 +/- 0.2 vs. 38.6 +/- 0.1 degrees C, p < 0.05), (T) over bar sk was lower (32.0 +/- 0.3 vs. 32.4 +/- 0.2 degrees C, p < 0.05), forearm sweating rate was lower (0.94 +/- 0.09 vs. 1.05 +/- 0.07 mg.cm(-2).min(-1), p < 0.05); and head (temporal) skin blood velocity was not different (1.67 +/- 0.21 vs. 1.51 +/- 0.24 Hz.10(3), NS). Conclusions: Elevation of plasma [glucose] prior to supine submaximal exercise in dehydrated men attenuates the increase of Tre without alteration of heat production, total body sweating, serum electrolytes and osmolality, or exercise-induced hypoglycemia: the mechanism may be enhanced peripheral blood flow that could enhance body heat loss. C1 NASA, Ames Res Ctr, Gravitat Res Branch 239 11, Lab Human Environm Physiol, Moffett Field, CA 94035 USA. San Francisco State Univ, Dept Sci Biol, San Francisco, CA 94132 USA. RP Greenleaf, JE (reprint author), NASA, Ames Res Ctr, Gravitat Res Branch 239 11, Lab Human Environm Physiol, Moffett Field, CA 94035 USA. NR 30 TC 2 Z9 2 U1 0 U2 1 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD JAN PY 1999 VL 70 IS 1 BP 35 EP 41 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 151EB UT WOS:000077706800007 PM 9895019 ER PT B AU Bellan, J Lathouwers, D AF Bellan, J Lathouwers, D BE Overend, RP Chornet, E TI TAR production from biomass pyrolysis in a fluidized bed reactor: A novel turbulent multiphase flow formulation SO BIOMASS: A GROWTH OPPORTUNITY IN GREEN ENERGY AND VALUE-ADDED PRODUCTS, VOLS 1 AND 2 LA English DT Proceedings Paper CT 4th Biomass Conference of the Americas on Growth Opportunity in Green Energy and Value-Added Products CY AUG 29-SEP 02, 1999 CL OAKLAND, CA SP US DOE, Nat Resource Canada, CA Energy Comm ID PNEUMATIC TRANSPORT; KINETIC-THEORY; 2-PHASE FLOWS; SMOOTH; DENSE; PARTICLES; SPHERES AB A novel multiphase flow model is presented for describing the pyrolysis of biomass in a 'bubbling' fluidized bed reactor. The mixture of biomass and sand in a gaseous flow is conceptualized as a particulate phase composed of two classes interacting with the carrier gaseous flow. The solid biomass is composed of three initial species: cellulose, hemicellulose and lignin. From each of these initial species, two nem solid species originate during pyrolysis: an 'active' species and a char, thus totaling seven solid-biomass species. The gas phase is composed of the original carrier gas (steam), tar and gas: the last two species originate from the volumetric pyrolysis reaction. The conservation equations are derived from the Boltzmann equations through ensemble averaging. Stresses in the gaseous phase are the sum of the Newtonian and Reynolds (turbulent) contributions. The particulate phase stresses are the sum of collisional and Reynolds contributions. Heat transfer between phases, and heat transfer between classes in the particulate phase is modeled, the last resulting from collisions between sand and biomass. Closure of the equations must be performed by modeling the Reynolds stresses for both phases. The results of a simplified version (first step) of the model are presented. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bellan, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 125-109, Pasadena, CA 91109 USA. NR 23 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI KIDLINGTON PA THE BOULEVARD, LANGFORD LANE,, KIDLINGTON OX5 1GB, OXFORD, ENGLAND BN 0-08-043019-8 PY 1999 BP 1145 EP 1151 PG 7 WC Energy & Fuels SC Energy & Fuels GA BP17M UT WOS:000084312500172 ER PT B AU Hartman, RC AF Hartman, RC BE Takalo, LO Sillanpaa, A TI CGRO observations of BL Lac objects and other blazars SO BL LAC PHENOMENON SE Astronomical Society of the Pacific Conference Series LA English DT Proceedings Paper CT Meeting on BL Lac Phenomenon CY JUN 22-26, 1998 CL TURKU, FINLAND ID GAMMA-RAY EMISSION; 3C-279; LACERTAE; FLARE AB Among the 68 blazars detected by EGRET with high confidence, roughly 25-30% are classified as BL Lac objects. Although most are of the LBL (RBL) subspecies, 4 HBLs (XBLs) have now been detected convincingly. In general, the BL Lacs appear to have slightly harder spectra than the other blazars, and to be somewhat less variable. On average, the LBLs are substantially less luminous in gamma rays than are the EGRET-detected quasars, and the gamma luminosity of the EGRET-detected HBLs is lower than that of the quasars by a factor of at least 10(2) - 10(4). One BL Lac object, BL Lacertae itself, received exceptionally good optical coverage during an EGRET target-of-opportunity hare observation in 1997 July. During a I-day miniflare in the middle of the EGRET observation, the optical and gamma-ray fluxes appeared to peak very close in time. For the only other blazar flare with comparable optical coverage, that of 3C 279 in 1996 Feb, there is little evidence for 1-day-scale gamma/optical correlation, although it was bright in both of those bands. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20904 USA. RP Hartman, RC (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20904 USA. EM rch@puccini.gsfc.nasa.gov NR 14 TC 2 Z9 2 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-79-1 J9 ASTR SOC P PY 1999 VL 159 BP 199 EP 208 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BM90V UT WOS:000080089400052 ER PT B AU Connaughton, V Robinson, CR McCollough, ML Laurent-Muehleisen, S AF Connaughton, V Robinson, CR McCollough, ML Laurent-Muehleisen, S BE Takalo, LO Sillanpaa, A TI BATSE observations of BL Lac objects. SO BL LAC PHENOMENON SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Meeting on BL Lac Phenomenon CY JUN 22-26, 1998 CL TURKU, FINLAND AB The Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory has been shown to be sensitive to non-transient hard X-ray sources in our galaxy, down to flux levels of 100 mCrab for daily measurements, 3 mCrab for integrations over several years. We use the continuous BATSE database and the Earth Occultation technique to extract average flux values between 20 and 200 keV from complete radio- and X-ray- selected BL Lac samples over a 2 year period. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Connaughton, V (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 8 TC 3 Z9 3 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-886733-79-1 J9 ASTR SOC P PY 1999 VL 159 BP 209 EP 212 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BM90V UT WOS:000080089400053 ER PT J AU Trejo, LJ Shensa, MJ AF Trejo, LJ Shensa, MJ TI Feature extraction of event-related potentials using wavelets: An application to human performance monitoring SO BRAIN AND LANGUAGE LA English DT Article DE wavelet; event-related potential; ERP; principal components; feature extraction; linear regression; neural networks; human performance monitoring; signal detection; vision AB This report describes the development and evaluation of mathematical models for predicting human performance from discrete wavelet transforms (DWT) of event-related potentials (ERP) elicited by task-relevant stimuli. The DWT was compared to principal components analysis (PCA) for representation of ERPs in linear regression and neural network models developed to predict a composite measure of human signal detection performance. Linear regression models based on coefficients of the decimated DWT predicted signal detection performance with half as many free parameters as comparable models based on PCA scores. In addition, the DWT-based models were more resistant to model degradation due to over-fitting than PCA-based models. Feed-forward neural networks were trained using the backpropagation algorithm to predict signal detection performance based on raw ERPs, PCA scores, or high-power coefficients of the DWT, Neural networks based on high-power DWT coefficients trained with fewer iterations, generalized to new data better, and were more resistant to overfitting than networks based on raw ERPs. Networks based on PCA scores did not generalize to new data as well as either the DWT network or the raw ERP network. The results show that wavelet expansions represent the ERP efficiently and extract behaviorally important features for use in linear regression or neural network models of human performance. The efficiency of the DWT is discussed in terms of its decorrelation and energy compaction properties. In addition, the DWT models provided evidence that a pattern of low-frequency activity (1 to 3.5 Hz) occurring at specific times and scalp locations is a reliable correlate of human signal detection performance. (C) 1999 Academic Press. C1 NASA, Ames Res Ctr, Human Factors Div, Human Informat Proc Res Branch, Stanford, CA 94305 USA. USN, Command Control & Ocean Surveillance Ctr, RDT&E Div, Washington, DC USA. RP Trejo, LJ (reprint author), NASA, Ames Res Ctr, Human Factors Div, Human Informat Proc Res Branch, Stanford, CA 94305 USA. NR 19 TC 33 Z9 33 U1 0 U2 4 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0093-934X J9 BRAIN LANG JI Brain Lang. PD JAN PY 1999 VL 66 IS 1 BP 89 EP 107 DI 10.1006/brln.1998.2026 PG 19 WC Audiology & Speech-Language Pathology; Linguistics; Neurosciences; Psychology, Experimental SC Audiology & Speech-Language Pathology; Linguistics; Neurosciences & Neurology; Psychology GA 180FP UT WOS:000079375700004 PM 10080866 ER PT J AU Petersen, WA Cifelli, RC Rutledge, SA Ferrier, BS Smull, BF AF Petersen, WA Cifelli, RC Rutledge, SA Ferrier, BS Smull, BF TI Shipborne dual-Doppler operations during TOGA COARE: Integrated observations of storm kinematics and electrification SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID RADAR OBSERVATIONS; CONVECTIVE CELLS; FLORIDA THUNDERSTORM; TROPICAL CONVECTION; MESOSCALE SYSTEMS; VERTICAL PROFILE; SQUALL LINE; PRECIPITATION; GATE; EVOLUTION AB Shipborne Doppler radar operations were conducted over the western Pacific warm pool during TOGA COARE using the Massachusetts Institute of Technology and NOAA TOGA C-band Doppler radars. Occasionally the ships carrying these radars were brought to within 50 km of each other to conduct coordinated dual-Doppler scanning. The dual-Doppler operations were considered a test of the logistical and engineering constraints associated with establishing a seagoing dual-Doppler configuration. A very successful dual-Doppler data collection period took place on 9 February 1993 when an oceanic squall line developed, intensified and propagated through the shipborne dual-Doppler lobes. Later on the same day, NOAA P-3 aircraft sampled a more intense squall line located approximately 400 km to the southeast of the shipborne operations. This study provides an overview of the shipborne dual-Doppler operations, followed by a comparison of the kinematic and precipitation structures of the convective systems sampled by the ships and aircraft. Special emphasis is placed on interpretation of the results relative to the electrical characteristics of each system. Soundings taken in the vicinity of the ship and aircraft cases exhibited similar thermodynamic instability and sheer. Yet Doppler radar analyses suggest that the aircraft case exhibited a larger degree of low-level forcing, stronger updrafts, more precipitation mass in the mixed-phase region of the clouds, and a relatively higher degree of electrification as evidenced by lightning observations. Conversely, convection in the ship case, while producing maximum cloud-top heights of 16 km, was associated with relatively weaker low-level forcing, weaker vertical development above the -5 degrees C level, moderate electric fields at the surface, and Little detectable lightning. Differences in the kinematic and precipitation structures were further manifested in composite vertical profiles of mean convective precipitation and vertical motion. When considered relative to the electrical properties of the two systems, the results provide further circumstantial evidence to support previously hypothesized vertical velocity and radar reflectivity thresholds that must be exceeded in the 0 degrees to -20 degrees C regions of tropical cumulonimbi prior to the occurrence of lightning. C1 Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Mesoscale Atmospher Proc Branch, Greenbelt, MD 20771 USA. Univ Washington, Joint Inst Study Atmosphere & Oceans, NOAA, Natl Severe Storms Lab, Seattle, WA 98195 USA. RP Petersen, WA (reprint author), Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. NR 64 TC 45 Z9 45 U1 1 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD JAN PY 1999 VL 80 IS 1 BP 81 EP 97 DI 10.1175/1520-0477(1999)080<0081:SDDODT>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160KR UT WOS:000078230100006 ER PT J AU Hasler, AF Palaniappan, K Kambhammetu, C Black, P Uhlhorn, E Chesters, D AF Hasler, AF Palaniappan, K Kambhammetu, C Black, P Uhlhorn, E Chesters, D TI High-resolution wind fields within the inner core and eye of a mature tropical cyclone from GOES 1-min images (vol 79, pg 2483, 1998) SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Correction C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Missouri, Dept Comp Sci & Comp Engn, Columbia, MO 65211 USA. Univ Delaware, Dept Comp & Informat Sci, Newark, DE 19716 USA. NOAA, Atlantic Oceanog & Meteorol Lab, Hurricane Res Div, Miami, FL 33149 USA. RP Hasler, AF (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Palaniappan, Kannappan/A-3231-2008; Uhlhorn, Eric/B-1336-2014 OI Uhlhorn, Eric/0000-0002-4759-5342 NR 1 TC 0 Z9 0 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD JAN PY 1999 VL 80 IS 1 BP 97 EP 97 PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 160KR UT WOS:000078230100007 ER PT S AU Yamaguchi, Y Fujisada, H Kudoh, M Kawakami, T Tsu, H Kahle, AB Pniel, M AF Yamaguchi, Y Fujisada, H Kudoh, M Kawakami, T Tsu, H Kahle, AB Pniel, M BE Tsuchiya, K TI ASTER instrument characterization and operation scenario SO CALIBRATION AND CHARACTERIZATION OF SATELLITE SENSORS SE ADVANCES IN SPACE RESEARCH LA English DT Article; Proceedings Paper CT A0 2 Symposium of COSPAR Scientific Commission A on Calibration and Characterization of Satellite Sensors, at the 32nd COSPAR Scientific Assembly CY JUL 12-19, 1998 CL NAGOYA, JAPAN SP Comm Space Res, Sci Commiss A, NASA, NOAA, Canadian Space Agcy, Ctr Natl Etudes Spatiales, European Space Agcy, Comm Space Res AB The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution multi-spectral imaging radiometer, and spectrally covers the visible and near-infrared, short-wave-infrared, and thermal infrared regions with 14 spectral bands, 15 to 90 m spatial resolution, and 60 km imaging swath. ASTER has the along-track stereoscopic viewing capability with B/H of 0.6 and cross-track pointing function for global coverage. Several new technologies such as long-life active cryocoolers are adopted to realize high observation performances. The radiometric, geometric, and spectral performances of the ASTER instrument were confirmed in the Proto Flight Model (PFM) tests. Since operation of the ASTER will be limited by various constraints such as duty cycle and pointing change controls, it is necessary to optimize the operation scenario for efficient data acquisition. Prioritization of data acquisition requests will be based on factors such as data category, user category, and science discipline. (C) 1999 COSPAR. Published by Elsevier Science Ltd. C1 Nagoya Univ, Chikusa Ku, Nagoya, Aichi 4648602, Japan. Sci Univ Tokyo, Noda, Chiba 2780022, Japan. Japan Resources Observ Syst Org, Chuo Ku, Tokyo 1040032, Japan. Earth Remote Sensing Data Anal Ctr, Chuo Ku, Tokyo 1040054, Japan. Geol Survey Japan, Tsukuba, Ibaraki 3058567, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yamaguchi, Y (reprint author), Nagoya Univ, Chikusa Ku, Furo Cho, Nagoya, Aichi 4648602, Japan. NR 6 TC 25 Z9 29 U1 1 U2 4 PU PERGAMON PRESS LTD PI OXFORD PA THE BOULEVARD LANGFORD LANE KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0273-1177 J9 ADV SPACE RES PY 1999 VL 23 IS 8 BP 1415 EP 1424 DI 10.1016/S0273-1177(99)00293-8 PG 10 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Remote Sensing SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences; Remote Sensing GA BN57L UT WOS:000082288400012 ER PT J AU Pollard, W Omelon, C Andersen, D McKay, C AF Pollard, W Omelon, C Andersen, D McKay, C TI Perennial spring occurrence in the Expedition Fiord area of western Axel Heiberg Island, Canadian High Arctic SO CANADIAN JOURNAL OF EARTH SCIENCES LA English DT Article ID CLIMATE AB This paper documents perennial spring activity at Expedition Fiord on western Axel Heiberg Island in the Canadian High Arctic. Two groups of mineralized springs occur. near the McGill University Axel Heiberg Research Station located at 79 degrees 26'N, 90 degrees 46'W. The first is at Gypsum Hill, 3 km from the terminus of the White and Thompson glaciers, and the second site is at Colour Peak, approximately 10 km downvalley near the head of Expedition Fiord. Each spring group consists of 20-40 vents spread over several hundred square metres. The highly mineralized nature of the discharge causes a freezing-point depression of 7-10 degrees C and produces a range of precipitates and travertine deposits. Year-round water temperature and discharge rate measurements have been obtained, demonstrating perennial activity at these sites. Results indicate that temperatures range from -4.0 to 6.6 degrees C among the individual sources; however, water temperatures at the various outlets remain constant throughout the year despite a mean annual air temperature of -15 degrees C. Although discharge from any one outlet is low (<0.5 to 2.0 L/s), the total discharge is substantial, each year producing several seasonal frost mounds and an icing 180000 - 300000 m(2) at the Gypsum Hill site. C1 McGill Univ, Dept Geog, Montreal, PQ H3A 2K6, Canada. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Pollard, W (reprint author), McGill Univ, Dept Geog, 805 Sherbrooke St W, Montreal, PQ H3A 2K6, Canada. RI Omelon, Christopher/B-8520-2011 OI Omelon, Christopher/0000-0003-4563-3189 NR 28 TC 43 Z9 43 U1 0 U2 1 PU CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS PI OTTAWA PA 1200 MONTREAL ROAD, BUILDING M-55, OTTAWA, ON K1A 0R6, CANADA SN 0008-4077 EI 1480-3313 J9 CAN J EARTH SCI JI Can. J. Earth Sci. PD JAN PY 1999 VL 36 IS 1 BP 105 EP 120 DI 10.1139/e98-097 PG 16 WC Geosciences, Multidisciplinary SC Geology GA 213XC UT WOS:000081297700009 ER PT J AU Vander Wal, RL Choi, MY AF Vander Wal, RL Choi, MY TI Pulsed laser heating of soot: morphological changes SO CARBON LA English DT Article DE soot; carbonization; combustion; graphitization; heat treatment; transmission electron microscopy ID CARBON; CRYSTALLINITY; EVOLUTION; GROWTH AB Pulsed laser heating of carbon soot is used here to achieve heating in excess of 10(11) K s(-1), cooling rates on the order of 10(9) s(-1) and total integrated times at elevated temperature of ca 1 milliseconds. To resolve detailed morphological changes induced in the soot by pulsed high intensity laser light, high resolution transmission electron microscopy and selected area electron diffraction are used to examine the laser-heated soot. Partial graphitization, formation of hollow particles and the average number of graphitic planes formed within soot primary particles upon high intensity pulsed laser heating are explained via a thermal annealing mechanism. This mechanism is discussed in the context of the initial physical structure of the soot. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 NASA, Lewis Res Ctr, NCMR, Cleveland, OH 44135 USA. Univ Illinois, Dept Mech Engn, Chicago, IL 60607 USA. RP Vander Wal, RL (reprint author), NASA, Lewis Res Ctr, NCMR, MS 110 3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 33 TC 50 Z9 52 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0008-6223 J9 CARBON JI Carbon PY 1999 VL 37 IS 2 BP 231 EP 239 DI 10.1016/S0008-6223(98)00169-9 PG 9 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 169EG UT WOS:000078734100008 ER PT J AU Jacobson, NS Leonhardt, TA Curry, DM Rapp, RA AF Jacobson, NS Leonhardt, TA Curry, DM Rapp, RA TI Oxidative attack of carbon/carbon substrates through coating pinholes SO CARBON LA English DT Article DE carbon/carbon composites; oxidation; surface treatment ID 1D-SIC/C/SIC COMPOSITE-MATERIALS; GASEOUS-DIFFUSION MODEL; HAFNIUM CARBIDE; KINETICS; MECHANISMS AB A critical issue with oxidation protected carbon/carbon composites used for spacecraft thermal protection is the formation of coating pinholes. In laboratory experiments, artificial pinholes were drilled through SiC-coatings on a carbon/carbon material and the material was oxidized at 600, 1000, and 1400 degrees C at reduced pressures ol air. The attack of the carbon/carbon was quantified by both weight loss and a novel cross-sectioning technique, A two-zone diffusion control model was adapted to analyze this problem. Agreement of the model with experiment was reasonable at 1000 and 1400 degrees C; however results at lower temperatures show clear deviations from the theory suggesting that surface reaction control plays a role. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NASA, Lewis Res Ctr Grp, NYMA Inc, Cleveland, OH USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Ohio State Univ, Dept Mat Sci & Engn, Columbus, OH 43210 USA. RP Jacobson, NS (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RI Jacobson, Nathan/A-9411-2009 NR 16 TC 26 Z9 27 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0008-6223 J9 CARBON JI Carbon PY 1999 VL 37 IS 3 BP 411 EP 419 DI 10.1016/S0008-6223(98)00206-1 PG 9 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 180TF UT WOS:000079400700004 ER PT J AU Hung, CC Corbin, J AF Hung, CC Corbin, J TI Synthesis and thermal stability of graphite-oxide-like materials SO CARBON LA English DT Letter DE graphite oxide; thermal stability C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Cleveland State Univ, Dept Chem, Cleveland, OH 44115 USA. RP Hung, CC (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 5 TC 7 Z9 7 U1 0 U2 8 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0008-6223 J9 CARBON JI Carbon PY 1999 VL 37 IS 4 BP 701 EP 705 PG 5 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 194VQ UT WOS:000080215300022 ER PT J AU Randolph, J Ayon, J Dirling, R Imbriale, W Miyake, R Le Queau, D Olalde, G Pierson, E Rawal, S Rivoire, B Robert, JF Royere, C Taylor, R Valentine, P Vaughn, W AF Randolph, J Ayon, J Dirling, R Imbriale, W Miyake, R Le Queau, D Olalde, G Pierson, E Rawal, S Rivoire, B Robert, JF Royere, C Taylor, R Valentine, P Vaughn, W TI The solar probe shield/antenna materials characterization SO CARBON LA English DT Article DE carbon/carbon composites; electrical properties; mechanical properties; optical properties AB This paper describes the development process used to select the shield/antenna material satisfying the design requirements of the Solar Probe mission that will encounter a flux at perihelion equivalent to an intensity of 3000 times greater than that at the Earth. A joint U.S.-French testing program was devised that would screen samples of carbon-carbon to determine the fabrication process that would produce the best thermal-optical and thermal-mechanical properties, lowest mass loss, and acceptable RF properties for temperatures up to 2400 K during shield operation. The thermal optical properties are emphasized since these determine the operating temperature and mass loss of the shield and are the most uncertain. The U.S. optical testing program relied on two facilities. The first facility used a high intensity halogen lamp to heat the sample. The temperature data were used in a heat balance equation to determine the solar absorptance/infrared emittance (alpha/epsilon) ratio given the known heat flux input. The emittance of the samples was determined, independently, by another specially calibrated facility that used Joule heating of the samples and measured the temperature by remote pyrometry that had been precisely calibrated. The French testing utilized a precisely designed chamber facility at the CNRS 1000 kW Solar Furnace at Odeillo Font Romeu and the data collected there are sufficient to identify the thermal-optical properties of the materials, as well as their mass loss characteristics at high temperatures including the principal carbon vapor species evolved. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Sci Applicat Int Corp, Fountain Valley, CA 92708 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. CNRS, IMP, Inst Sci & Genie Mat & Prod, Odeillo, Font Romeu, France. Gen Atom Co, San Diego, CA 92186 USA. Ctr Etud Spatiale Rayonnements, Toulouse, France. RP Randolph, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 14 TC 12 Z9 13 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0008-6223 J9 CARBON JI Carbon PY 1999 VL 37 IS 11 BP 1731 EP 1739 DI 10.1016/S0008-6223(99)00051-2 PG 9 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 248DC UT WOS:000083259200007 ER PT J AU Schatten, H Chakrabarti, A Taylor, M Sommer, L Levine, H Anderson, K Runco, M Kemp, R AF Schatten, H Chakrabarti, A Taylor, M Sommer, L Levine, H Anderson, K Runco, M Kemp, R TI Effects of spaceflight conditions on fertilization and embryogenesis in the sea urchin Lytechinus pictus SO CELL BIOLOGY INTERNATIONAL LA English DT Article DE microgravity; spaceflight; sea urchins; microfilaments; microtubules; cortical granules; secretion; membranes ID EGGS; CENTROSOMES; MICROTUBULES; LYMPHOCYTES; DIVISION; CYCLE; CELLS AB Calcium loss and muscle atrophy are two of the main metabolic changes experienced by astronauts and crew members during exposure to microgravity in space. Calcium and cytoskeletal events were investigated within sea urchin embryos which were cultured in space under both microgravity and Ig conditions. Embryos were fixed at time-points ranging from 3 h to 8 days after fertilization. Investigative emphasis was placed upon: (1) sperm-induced calcium-dependent exocytosis and cortical granule secretion, (2) membrane fusion of cortical granule and plasma membranes; (3) microfilament polymerization and microvilli elongation; and (5) embryonic development into morula, blastula, gastrula, and pluteus stages. For embryos cultured under microgravity conditions, the processes of cortical granule discharge, fusion of cortical granule membranes with the plasma membrane, elongation of microvilli and elevation of the fertilization coat were reduced in comparison with embryos cultured at 1 g in space and under normal conditions on Earth. Also, 4% of all cells undergoing division in microgravity showed abnormalities in the centrosome-centriole complex. These abnormalities were not observed within the Ig flight and ground control specimens, indicating that significant alterations in sea urchin development processes occur under microgravity conditions. (C) 1999 Academic Press. C1 Univ Missouri, Dept Vet Pathobiol, Columbia, MO 65211 USA. Dynamac Corp, Gravitat Biol Lab, Kennedy Space Ctr, FL 32899 USA. Bionet Corp, Flight Dev Grp, Kennedy Space Ctr, FL 32899 USA. NASA, Lyndon B Johnson Space Ctr, Astronaut Off, Houston, TX 77058 USA. RP Schatten, H (reprint author), Univ Missouri, Dept Vet Pathobiol, 1600 E Rollins St, Columbia, MO 65211 USA. NR 44 TC 10 Z9 11 U1 0 U2 4 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 1065-6995 J9 CELL BIOL INT JI Cell Biol. Int. PY 1999 VL 23 IS 6 BP 407 EP 415 DI 10.1006/cbir.1999.0371 PG 9 WC Cell Biology SC Cell Biology GA 274BB UT WOS:000084742900003 PM 10623420 ER PT B AU Gezari, D AF Gezari, D BE Falcke, H Cotera, A Duschl, WJ Melia, F Rieke, MJ TI Sgr A* in the mid-infrared reference frame: The relationship between the radio and infrared sources in the central parsec SO CENTRAL PARSECS OF THE GALAXY SE Astronomical Society of the Pacific Conference Series LA English DT Proceedings Paper CT Galactic Center Workshop on the Central Parsecs of the Galaxy CY SEP 07-11, 1998 CL TUCSON, AZ SP Univ Heidelberg, Univ Arizona, Phys Dept, NICMOS, Steward Observ, Max Planck Inst Radioastronomie, Bonn, Inst Theoret Astrophys, Heidelberg ID SAGITTARIUS-A; GALACTIC-CENTER AB Comparison of the ionized gas and warm dust in the Sgr A West complex shows shifts in the peak positions between the infrared and radio data, as well as shifts in the positions of the IRS source peaks within the infrared image data, which could reveal the influence of the luminous sources which heat the dust and ionize the gas. No clear trend can be found in the comparison of radio/infrared or near-infrared/mid-infrared source positions which can be attributed to the effects of an exceptional source at any specific location (such as near Sgr A*), or to the results of any global process (such as ionization by a central radiation field). Thus the observations suggest that the observed position shifts are due to local effects and conditions at the individual sources in each case, and lend no additional weight to the argument that a dominant luminous or massive object is present near the position of Sgr A*. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gezari, D (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 20 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-012-9 J9 ASTR SOC P PY 1999 VL 186 BP 234 EP 239 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BP16P UT WOS:000084260600025 ER PT J AU Brown, GE Henrich, VE Casey, WH Clark, DL Eggleston, C Felmy, A Goodman, DW Gratzel, M Maciel, G McCarthy, MI Nealson, KH Sverjensky, DA Toney, MF Zachara, JM AF Brown, GE Henrich, VE Casey, WH Clark, DL Eggleston, C Felmy, A Goodman, DW Gratzel, M Maciel, G McCarthy, MI Nealson, KH Sverjensky, DA Toney, MF Zachara, JM TI Metal oxide surfaces and their interactions with aqueous solutions and microbial organisms SO CHEMICAL REVIEWS LA English DT Review ID X-RAY-ABSORPTION; SCANNING-TUNNELING-MICROSCOPY; NUCLEAR-MAGNETIC-RESONANCE; ATOMIC-FORCE MICROSCOPE; SOLID-STATE NMR; SHEWANELLA-PUTREFACIENS MR-1; LIGAND-PROMOTED DISSOLUTION; LASER-INDUCED FLUORESCENCE; DENSITY-FUNCTIONAL-THEORY; MINERAL-WATER INTERFACE C1 Stanford Univ, Dept Geol & Environm Sci, Surface & Aqueous Geochem Grp, Stanford, CA 94305 USA. Yale Univ, Dept Appl Phys, Surface Sci Lab, New Haven, CT 06520 USA. Univ Calif Davis, Dept Land Air & Water Resources, Davis, CA 95616 USA. Los Alamos Natl Lab, Div Nucl Mat Technol, GT Seaborg Inst Transactinium Sci, Los Alamos, NM 87545 USA. Univ Wyoming, Dept Geol & Geophys, Laramie, WY 82071 USA. Pacific NW Natl Lab, Environm Mol Sci Lab, Richland, WA 99352 USA. Texas A&M Univ, Dept Chem, College Stn, TX 77843 USA. Ecole Polytech Fed Lausanne, Inst Chim Phys, CH-1015 Lausanne, Switzerland. Colorado State Univ, Dept Chem, Ft Collins, CO 80523 USA. Pacific NW Natl Lab, Environm Mol Sci Lab, Theory Modeling & Simulat Grp, Richland, WA 99352 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA. IBM Corp, Almaden Res Ctr, San Jose, CA 95120 USA. RP Stanford Univ, Dept Geol & Environm Sci, Surface & Aqueous Geochem Grp, Stanford, CA 94305 USA. RI Graetzel, Michael/G-4870-2011; Sverjensky, Dimitri/A-4612-2017; Clark, David/A-9729-2011 NR 820 TC 634 Z9 640 U1 23 U2 256 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0009-2665 EI 1520-6890 J9 CHEM REV JI Chem. Rev. PD JAN PY 1999 VL 99 IS 1 BP 77 EP 174 DI 10.1021/cr980011z PG 98 WC Chemistry, Multidisciplinary SC Chemistry GA 173MN UT WOS:000078984500003 ER PT B AU Valinia, A White, N Tananbaum, H AF Valinia, A White, N Tananbaum, H CA Constellation-X Team BE Mazure, A LeFevre, O LeBrun, V TI The high redshift universe as observed with the constellation-X observatory SO CLUSTERING AT HIGH REDSHIFT SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Meeting on Clustering at High Redshift CY JUN 29-JUL 02, 1999 CL MARSEILLE, FRANCE AB Constellation-X is a high throughput X-ray facility emphasizing observations at high spectral resolution (E/Delta E similar to 300 - 3000), providing a factor of 100 increase in sensitivity over current high resolution X-ray spectroscopy missions while covering a broad bandpass (0.25-60 keV). When observations commence toward the end of next decade, Constellation-X will address many fundamental questions related to the formation and evolution of structure in the Universe. Constellation-X will determine the properties of galaxies and clusters of galaxies and their interaction over a broad range of redshift allowing comparison of observations with current models of structure formation. Constellation-X will determine the history of star formation in the Universe via observations of the cluster abundances to redshifts beyond 2. Finally, many of the baryons predicted by Big Bang nucleosynthesis and subsequent stellar processing seem to be "missing". Constellation-X has the capability to detect them in a hot, metal enriched Intergalactic Medium (IGM). C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Valinia, A (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 1 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-027-7 J9 ASTR SOC P PY 1999 VL 200 BP 458 EP 459 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BQ39K UT WOS:000088232100097 ER PT J AU Vander Wal, RL Ticich, TM Stephens, AB AF Vander Wal, RL Ticich, TM Stephens, AB TI Can soot primary particle size be determined using laser-induced incandescence? SO COMBUSTION AND FLAME LA English DT Article ID JET DIFFUSION FLAMES; VOLUME FRACTION; GROWTH; AIR AB Temporally resolved laser-induced incandescence (LII) signals are obtained from different size primary particles produced by the diffusion flames of methane, ethane, ethylene, and acetylene. These results represent the first direct comparison between primary particle sizes based on optical measurements and those directly measured through transmission electron microscopy (TEM). Analysis of the data at different detected wavelengths as suggested by theory reveals a nonmonotonic relation with primary particle size as measured by TEM. Two alternative measures of the temporal decay of the signal at a single detected wavelength reveal a correlation with primary particle size within soot aggregates produced by the different flames. Comparison between predicted primary particle size based on the calibrations using the temporal analysis of the LII signal and TEM measurements reveals agreement within the growth region (low axial heights) and very late in the oxidation region (high axial heights) within an ethylene gas-jet diffusion flame. Significant differences exist at intermediate positions. These differences are interpreted as representing the effects of cluster-cluster aggregation within the oxidation region. (C) 1998 by The Combustion Institute C1 NASA, Lewis Res Ctr, NCMR, Cleveland, OH 44135 USA. Centenary Coll Louisiana, Dept Chem, Shreveport, LA 71134 USA. RP Vander Wal, RL (reprint author), NASA, Lewis Res Ctr, NCMR, MS 110-3,21000 Brookpark Rd, Cleveland, OH 44135 USA. NR 20 TC 78 Z9 78 U1 0 U2 9 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD JAN PY 1999 VL 116 IS 1-2 BP 291 EP 296 DI 10.1016/S0010-2180(98)00040-6 PG 6 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 116GZ UT WOS:000075717300021 ER PT J AU Thomas, RE Harris, PM Rice, SD AF Thomas, RE Harris, PM Rice, SD TI Survival in air of Mytilus trossulus following long-term exposure to spilled Exxon Valdez crude oil in Prince William sound SO COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-PHARMACOLOGY TOXICOLOGY & ENDOCRINOLOGY LA English DT Article DE aerial exposure; Exxon Valdez; Mytilus trossulus; polynuclear aromatic hydrocarbons; stress on stress; survival in air ID STRESS-RESPONSE; BLUE MUSSEL; EDULIS-L; SEDIMENTS; SALINITY; GROWTH AB Mussels, Mytilus trossulus, were sampled in 1996 from beaches in Prince William Sound (PWS) which contained residual oil resulting from the Exxon Valdez oil spill of March 1989, and from one beach which had been lightly oiled in 1989, but contained no residual oil in 1996. The latter mussels served as un-oiled references. Mussels were also collected from Tee Harbor, Southeast Alaska, to be used as an additional reference group. Where the size of the individuals in the resident population would permit, two size groups were sampled, 32-35 and 18-20 mm in length. Polynuclear aromatic hydrocarbon (PAH) concentrations in mussel tissue, and air survival time were determined for each group of mussels. Total PAH concentrations were significantly greater in tissue of mussels from oiled beds (0.6-2.0 mu g g(-1)) than from references (0.01-0.12 mu g g(-1)) (P < 0.01). Oil-exposed mussels had significantly lower LT50 values (P < 0.05) for air survival than reference groups. Tolerance of small mussels to air exposure was significantly greater (P < 0.01) than large mussels in both the unoiled reference and oil exposed groups. (C) 1999 Elsevier Science Inc. All rights reserved. C1 Calif State Univ Los Angeles, Dept Biol Sci, Chico, CA 95929 USA. Natl Marine Fisheries Serv, Auke Bay Lab, Juneau, AK 99801 USA. RP Thomas, RE (reprint author), Calif State Univ Los Angeles, Dept Biol Sci, Chico, CA 95929 USA. EM bthomas@csuchico.edu NR 35 TC 30 Z9 30 U1 1 U2 11 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0742-8413 J9 COMP BIOCHEM PHYS C JI Comp. Biochem. Physiol. C-Pharmacol. Toxicol. Endocrinol. PD JAN PY 1999 VL 122 IS 1 BP 147 EP 152 DI 10.1016/S0742-8413(98)10098-1 PG 6 WC Biochemistry & Molecular Biology; Endocrinology & Metabolism; Toxicology; Zoology SC Biochemistry & Molecular Biology; Endocrinology & Metabolism; Toxicology; Zoology GA 160UY UT WOS:000078250700017 PM 10190039 ER PT J AU Thomas, RE Brodersen, C Carls, MG Babcock, M Rice, SD AF Thomas, RE Brodersen, C Carls, MG Babcock, M Rice, SD TI Lack of physiological responses to hydrocarbon accumulation by Mytilus trossulus after 3-4 years chronic exposure to spilled Exxon Valdez crude oil in Prince William Sound SO COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-PHARMACOLOGY TOXICOLOGY & ENDOCRINOLOGY LA English DT Article DE byssal thread; clearance rate; condition index; glycogen; exxon valdez; Mytilus trossulus; polynuclear aromatic hydrocarbon ID MUSSELS; EDULIS; SEDIMENTS; GROWTH AB Mussels, Mytilus trossulus, were sampled in 1992 and 1993 from beaches in Prince William Sound that had been oiled by the Exxon Valdez spill of March, 1989. At some of the oiled beaches, mussels were collected from beds overlying oiled sediments, and from bedrock adjacent to these beds. Mussels were also collected from beaches within the Sound that had not been impacted by the spill. Polynuclear aromatic hydrocarbon (PAH) concentrations in mussel tissue, physiological responses (byssal thread production, condition index, clearance rate, and glycogen content), were determined for each group of mussels. Total PAH concentrations in mussel tissue ranged from 0 to 6 mu g g(-1), and were significantly greater in mussels from oiled beds than those from reference beds. No significant differences were noted in byssal thread production, condition index, clearance rate, or glycogen content between oiled sample sites and reference sites. The lack of physiological response was surprising because mussels in this study were chronically exposed to PAH for 3-4 years, and none of the physiological responses measured appeared to be affected by that exposure. The lack of a physiological response suggests that chronically exposed mussels may develop a physiological tolerance to PAH, but we recognize that these measures may not have been sensitive enough to discriminate response from background noise. (C) 1999 Elsevier Science Inc. All rights reserved. C1 Calif State Univ Los Angeles, Dept Biol Sci, Chico, CA 95929 USA. Natl Ocean & Atmospher Adm, Natl Marine Fisheries Serv, Auke Bay Lab, Juneau, AK 99801 USA. RP Thomas, RE (reprint author), Calif State Univ Los Angeles, Dept Biol Sci, Chico, CA 95929 USA. EM bthomas@csuchico.edu NR 37 TC 25 Z9 25 U1 1 U2 12 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0742-8413 J9 COMP BIOCHEM PHYS C JI Comp. Biochem. Physiol. C-Pharmacol. Toxicol. Endocrinol. PD JAN PY 1999 VL 122 IS 1 BP 153 EP 163 DI 10.1016/S0742-8413(98)10099-3 PG 11 WC Biochemistry & Molecular Biology; Endocrinology & Metabolism; Toxicology; Zoology SC Biochemistry & Molecular Biology; Endocrinology & Metabolism; Toxicology; Zoology GA 160UY UT WOS:000078250700018 PM 10190040 ER PT J AU Schulz, MJ Pai, PF Inman, DJ AF Schulz, MJ Pai, PF Inman, DJ TI Health monitoring and active control of composite structures using piezoceramic patches SO COMPOSITES PART B-ENGINEERING LA English DT Article DE piezoceramics; vibration AB This paper presents new techniques under development for monitoring the health and suppressing the vibration of flexible composite structures. The techniques use piezoceramic patches bonded to the structure for actuation and sensing. Simulations and experiments are presented to demonstrate the utility of the methods for beam and panel structures. Limitations of piezoceramic materials are discussed, and suggestions are given for improving the techniques and for developing new uses of piezoceramic materials and smart structures. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 N Carolina Agr & Technol State Univ, NASA, Ctr Aerosp Res, Greensboro, NC 27411 USA. N Carolina Agr & Technol State Univ, NSF, Ctr Adv Mat & Smart Struct, Dept Engn Mech, Greensboro, NC 27411 USA. Univ Missouri, Dept Mech & Aerosp Engn, Struct Mech & Control Lab, Columbia, MO 65211 USA. Virginia Polytech Inst & State Univ, Ctr Intelligent Mat & Struct, Blacksburg, VA 24061 USA. RP Schulz, MJ (reprint author), N Carolina Agr & Technol State Univ, NASA, Ctr Aerosp Res, Greensboro, NC 27411 USA. NR 48 TC 53 Z9 59 U1 0 U2 2 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 1359-8368 J9 COMPOS PART B-ENG JI Compos. Pt. B-Eng. PY 1999 VL 30 IS 7 BP 713 EP 725 DI 10.1016/S1359-8368(99)00034-7 PG 13 WC Engineering, Multidisciplinary; Materials Science, Composites SC Engineering; Materials Science GA 265ZR UT WOS:000084276600011 ER PT J AU Aboudi, J Pindera, MJ Arnold, SM AF Aboudi, J Pindera, MJ Arnold, SM TI Higher-order theory for functionally graded materials SO COMPOSITES PART B-ENGINEERING LA English DT Article DE higher-order theory; functionally graded materials; microstructural tailoring/optimization ID METAL-MATRIX COMPOSITES; THERMAL RESIDUAL-STRESSES; FINITE-ELEMENT ANALYSIS; MICROMECHANICAL ANALYSIS; THERMOPLASTIC RESPONSE; BARRIER COATINGS; FIBER; MODEL; OPTIMIZATION; INTERFACES AB This paper presents the full generalization of the Cartesian coordinate-based higher-order theory for functionally graded materials developed by the authors during the past several years. This theory circumvents the problematic use of the standard micromechanical approach, based on the concept of a representative volume element, commonly employed in the analysis of functionally graded composites by explicitly coupling the local (microstructural) and global (macrostructural) responses. The theoretical framework is based on volumetric averaging of the various field quantities, together with imposition of boundary and interfacial conditions in an average sense between the subvolumes used to characterize the composite's functionally graded microstructure. The generalization outlined herein involves extension of the theoretical framework to enable the analysis of materials characterized by spatially variable microstructures in three directions. Specialization of the generalized theoretical framework to previously published versions of the higher-order theory for materials functionally graded in one and two directions is demonstrated. In the applications part of the paper we summarize the major findings obtained with the one-directional and two-directional versions of the higher-order theory. The results illustrate both the fundamental issues related to the influence of microstructure on microscopic and macroscopic quantities governing the response of composites and the technologically important applications. A major issue addressed herein is the applicability of the classical homogenization schemes in the analysis of functionally graded materials. The technologically important applications illustrate the utility of functionally graded microstructures in tailoring the response of structural components in a variety of applications involving uniform and gradient thermomechanical loading. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 Univ Virginia, Charlottesville, VA 22903 USA. Tel Aviv Univ, IL-69978 Ramat Aviv, Israel. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Pindera, MJ (reprint author), Univ Virginia, Charlottesville, VA 22903 USA. EM mp3g@virginia.edu NR 59 TC 190 Z9 193 U1 1 U2 27 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 1359-8368 J9 COMPOS PART B-ENG JI Compos. Pt. B-Eng. PY 1999 VL 30 IS 8 BP 777 EP 832 DI 10.1016/S1359-8368(99)00053-0 PG 56 WC Engineering, Multidisciplinary; Materials Science, Composites SC Engineering; Materials Science GA 271CF UT WOS:000084575900001 ER PT J AU Morscher, GN AF Morscher, GN TI Modal acoustic emission of damage accumulation in a woven SiC/SiC composite SO COMPOSITES SCIENCE AND TECHNOLOGY LA English DT Article ID CRACKING; FAILURE AB An approach to analyzing the tensile behavior and damage accumulation of ceramic composites is described and applied to a SiC-fiber-reinforced SiC-matrix composite. Monotonic tensile tests and load/unload/reload tensile tests were performed. Modal acoustic emission (AE) was used to monitor the extent of damage over the entire stress/strain curve. Microscopy of polished sections was performed to determine the extent of damage and related to the AE data. Damage accumulation in the matrix reduced the speed of sound through the matrix for acoustic events and was related to a reduction in elastic modulus. The location of events in the gage section was determined and related to the strain at which they occurred. The amplitude and frequency content of the event waveforms were used to correlate the acoustic events with the stress/strain curve and physical sources. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 Case Western Reserve Univ, NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Morscher, GN (reprint author), Case Western Reserve Univ, NASA, Lewis Res Ctr, MS-106-5, Cleveland, OH 44135 USA. NR 19 TC 77 Z9 88 U1 4 U2 19 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0266-3538 J9 COMPOS SCI TECHNOL JI Compos. Sci. Technol. PY 1999 VL 59 IS 5 BP 687 EP 697 DI 10.1016/S0266-3538(98)00121-3 PG 11 WC Materials Science, Composites SC Materials Science GA 191KZ UT WOS:000080022800007 ER PT B AU Sayir, A AF Sayir, A BE Pechenik, A Kalia, RK Vashishta, P TI Directional solidification of eutectic ceramics SO COMPUTER-AIDED DESIGN OF HIGH-TEMPERATURE MATERIALS SE TOPICS IN PHYSICAL CHEMISTRY: A SERIES OF ADVANCED TEXTBOOKS AND MONOGRAPHS LA English DT Proceedings Paper CT International Conference on Computer Aided Design of High Temperature Materials CY JUL 30-AUG 02, 1997 CL SANTA FE, NM ID MULLITE C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Sayir, A (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 34 TC 14 Z9 14 U1 0 U2 3 PU OXFORD UNIV PRESS PI NEW YORK PA 198 MADISON AVENUE, NEW YORK, NY 10016 USA BN 0-19-512050-7 J9 T PHYS CHEM SER PY 1999 BP 197 EP 211 PG 15 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA BP18E UT WOS:000084339600016 ER PT S AU Finckenor, J Spurrier, M AF Finckenor, J Spurrier, M BE Hernandez, S Kassab, AJ Brebbia, CA TI Design optimization and analysis of a composite honeycomb intertank SO COMPUTER AIDED OPTIMUM DESIGN OF STRUCTURES VI SE STRUCTURES AND MATERIALS LA English DT Proceedings Paper CT 6th International Conference on Computer Aided Optimum Design of Structures (OPTI 99) CY MAR 16-18, 1999 CL ORLANDO, FL SP Univ Coruna Spain, Univ Cent Florida, Wessex Inst Technol AB Intertanks, the structure between tanks of launch vehicles, are prime candidates for weight reduction of rockets. This paper discusses the optimization and detailed analysis of a 96 " (2.44 m) diameter, 77 " (1.85 m) tall intertank. The structure has composite face sheets and an aluminum honeycomb core. The ends taper to a thick built-up laminate for a double lap bolted shear joint. It comprises 8 full length panels joined with bonded double lap joints. The nominal line load is 4000 lb/in (7*10(5) N/m). Optimization is by Genetic Algorithm and minimizes weight by varying core thickness, number and orientation of acreage and build-up plies, and the size, number and spacing of bolts. A variety of cases were run with populations up to 2000 and chromosomes as long as 150 bits. Constraints were buckling, face stresses (normal, shear, wrinkling and dimpling), bolt stress, and bolt hole stresses (bearing, net tension, wedge splitting, shear out and tension/shear out). Analysis is by a combination of theoretical solutions and empirical data. After optimization, a series of coupon tests were performed in conjunction with a rigorous analysis involving a variety of finite element models. The analysis and test resulted in several small changes to the optimized design. The intertank has undergone a 265,000 lb (1.2*10(6) N) limit load test and been mated with a composite liquid hydrogen tank. The tank/intertank unit is being installed in a test stand where it will see 200 thermal/load cycles. Afterwards the intertank will be demated and loaded in compression to failure. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Finckenor, J (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 6 TC 0 Z9 0 U1 0 U2 1 PU COMPUTATIONAL MECHANICS PUBLICATIONS LTD PI SOUTHAMPTON PA ASHURST LODGE, SOUTHAMPTON S04 2AA, HANTS, ENGLAND SN 1462-6055 BN 1-85312-681-0 J9 STRUCT MAT PY 1999 VL 5 BP 257 EP 266 PG 10 WC Engineering, Aerospace; Computer Science, Interdisciplinary Applications; Engineering, Manufacturing; Engineering, Civil; Engineering, Mechanical SC Engineering; Computer Science GA BN10Z UT WOS:000080737200024 ER PT J AU Abdel-Tawab, K Noor, AK AF Abdel-Tawab, K Noor, AK TI A fuzzy-set analysis for a dynamic thermo-elastoviscoplastic damage response SO COMPUTERS & STRUCTURES LA English DT Article DE dynamic response; viscoplasticity; damage; sensitivity; fuzzy-set; Ti-6Al-4V ID GROWTH; DEFORMATION; TI-6AL-4V; SOLIDS; LOCALIZATION; NUCLEATION; FRACTURE; STRAIN AB A computational fuzzy-set based approach is used to study variability (uncertainty) in the mechanical response of dynamically-loaded simple structural components. The mechanical response is described by a thermo-elastoviscoplastic material model that accounts for damage. The uncertainty in the response is associated with pre-selected variations in material parameters. Sensitivity studies are performed to identify the material parameters which have the most significant effect on the response. Those parameters are then assumed to be fuzzy, and time histories of the possibility distributions of the response quantities are constructed. Numerical results are presented for a titanium alloy Ti-6Al-4V. Published by Elsevier Science Ltd. C1 Univ Virginia, Ctr Adv Computat Technol, NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Noor, AK (reprint author), Univ Virginia, Ctr Adv Computat Technol, NASA, Langley Res Ctr, Hampton, VA 23681 USA. EM a.k.noor@larc.nasa.gov NR 24 TC 13 Z9 13 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7949 EI 1879-2243 J9 COMPUT STRUCT JI Comput. Struct. PD JAN PY 1999 VL 70 IS 1 BP 91 EP 107 DI 10.1016/S0045-7949(98)00162-X PG 17 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA 166DX UT WOS:000078561900008 ER PT S AU Desharnais, J Gupta, V Jagadeesan, R Panangaden, P AF Desharnais, J Gupta, V Jagadeesan, R Panangaden, P BE Baeten, JCM Mauw, S TI Metrics for labeled Markov systems SO CONCUR '99: CONCURRENCY THEORY SE Lecture Notes in Computer Science LA English DT Article; Proceedings Paper CT 10th International Conference on Concurrency Theory (CONCUR 99) CY AUG 24-27, 1999 CL EINDHOVEN, NETHERLANDS SP Inst Programming Res & Algorithm, Philips Res Eindhoven, Eindhoven Embedded Syst Inst ID PROBABILISTIC PROCESSES; MODEL CHECKING; AUTOMATA AB Partial Labeled Markov Chains (p1Mc) generalize process algebra and traditional Markov chains. They provide a foundation for interacting discrete probabilistic systems. Existing notions of process equivalence are too sensitive to the exact probabilities of transitions in p1Mcs. This paper studies more robust notions of "approximate" equivalence between p1Mcs. C1 McGill Univ, Sch Comp Sci, Montreal, PQ, Canada. NASA, Ames Res Ctr, Auton & Robot Area, Moffett Field, CA 94035 USA. Loyola Univ, Dept Math & Comp Sci, Chicago, IL 60626 USA. RP McGill Univ, Sch Comp Sci, Montreal, PQ, Canada. NR 35 TC 49 Z9 49 U1 0 U2 4 PU SPRINGER-VERLAG BERLIN PI BERLIN PA HEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANY SN 0302-9743 BN 3-540-66425-4 J9 LECT NOTES COMPUT SC PY 1999 VL 1664 BP 258 EP 273 PG 16 WC Computer Science, Theory & Methods SC Computer Science GA BQ22X UT WOS:000087625300019 ER PT S AU Luttgen, G von der Beeck, M Cleaveland, R AF Luttgen, G von der Beeck, M Cleaveland, R BE Baeten, JCM Mauw, S TI Statecharts via process algebra SO CONCUR '99: CONCURRENCY THEORY SE Lecture Notes in Computer Science LA English DT Article; Proceedings Paper CT 10th International Conference on Concurrency Theory (CONCUR 99) CY AUG 24-27, 1999 CL EINDHOVEN, NETHERLANDS SP Inst Programming Res & Algorithm, Philips Res Eindhoven, Eindhoven Embedded Syst Inst ID COMPOSITIONAL SEMANTICS; SYSTEMS; LANGUAGE AB Statecharts is a visual language for specifying the behavior of reactive systems. The language extends finite-state machines with concepts of hierarchy, concurrency, and priority. Despite its popularity as a design notation for embedded systems, precisely defining its semantics has proved extremely challenging. In this paper, we present a simple process algebra, called Statecharts Process Language (SPL), which is expressive enough for encoding Statecharts in a structure-preserving and semantics-preserving manner. We also establish that the behavioral equivalence bisimulation, when applied to SPL, preserves Statecharts semantics. C1 NASA, Langley Res Ctr, Inst Comp Appl Sci & Engn, Hampton, VA 23681 USA. Tech Univ Munich, Dept Comp Sci, D-80290 Munich, Germany. SUNY Stony Brook, Dept Comp Sci, Stony Brook, NY 11794 USA. RP NASA, Langley Res Ctr, Inst Comp Appl Sci & Engn, Hampton, VA 23681 USA. EM luettgen@icase.edu; beeck@in.tum.de; rance@cs.sunysb.edu NR 28 TC 11 Z9 11 U1 0 U2 0 PU SPRINGER-VERLAG BERLIN PI BERLIN PA HEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANY SN 0302-9743 BN 3-540-66425-4 J9 LECT NOTES COMPUT SC PY 1999 VL 1664 BP 399 EP 414 PG 16 WC Computer Science, Theory & Methods SC Computer Science GA BQ22X UT WOS:000087625300028 ER PT S AU Truszkowski, W Hallock, H Kurien, J AF Truszkowski, W Hallock, H Kurien, J BE Klusch, M Shehory, OM Weiss, G TI Agent technology from a NASA perspective SO COOPERATIVE INFORMATION AGENTS III, PROCEEDINGS SE LECTURE NOTES IN ARTIFICIAL INTELLIGENCE LA English DT Article; Proceedings Paper CT 3rd International Workshop on Cooperative Information Agents CY JUL 31-AUG 02, 1999 CL UPPSALA, SWEDEN SP Deutsch Telekom AG, Berkom GmbH, Berlin, George Mason Univ, Fairfax, Daimler Chrysler AG, Res & Technol, Berlin, Active Online Syst Ltd, London, AgentLink ESPRIT Network Excellence Agent Based Comp, German Comp Soc, Uppsala Univ, Comp Sci Dept AB NASA's drive toward realizing higher levels of autonomy, in both its ground and space systems, is supporting an active and growing interest in agent technology. This paper will address the expanding research in this exciting technology area. As examples of current work, the Lights-Out Ground Operations System (LOGOS), under prototyping at the Goddard Space Flight Center (GSFC), and the spacecraft-oriented Remote Agent project under development at the Ames Research Center (ARC) and the Jet Propulsion Laboratory (JPL) will be presented. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Truszkowski, W (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 13 TC 1 Z9 1 U1 0 U2 1 PU SPRINGER-VERLAG BERLIN PI BERLIN PA HEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANY SN 0302-9743 BN 3-540-66325-8 J9 LECT NOTES ARTIF INT PY 1999 VL 1652 BP 1 EP 33 PG 33 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems SC Computer Science GA BQ61U UT WOS:000088970300001 ER PT S AU Kolb, EW AF Kolb, EW BE Caldwell, DO TI A view of the early universe SO COSMO-98: SECOND INTERNATIONAL WORKSHOP ON PARTICLE PHYSICS AND THE EARLY UNIVERSE SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 2nd International Workshop on Particle Physics and the Early Universe CY NOV 15-20, 1998 CL ASILOMAR, CA ID COSMIC STRUCTURE FORMATION; DARK-MATTER; INFLATION; PARTICLES; MODELS AB During this conference we have heard a great deal about recent progress in understanding the development of cosmic structures from small initial seed perturbations. In these concluding remarks, I would like to comment on the tno parts of the picture involving elementary-particle physics: 1) the generation of the seed perturbations in the early universe during inflation, and 2) the nature of the dark matter. C1 NASA, Fermilab Theoret Astrophys Grp, Fermi Natl Accelerator Lab, Washington, DC 20546 USA. RP Kolb, EW (reprint author), NASA, Fermilab Theoret Astrophys Grp, Fermi Natl Accelerator Lab, Washington, DC 20546 USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 1-56396-853-3 J9 AIP CONF PROC PY 1999 VL 478 BP 3 EP 9 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA BN58D UT WOS:000082305100001 ER PT B AU Marmaro, GM AF Marmaro, GM BE Hylko, JM Salyer, RL TI Launch site radiological emergency response for the Cassini Mission SO CREATION AND FUTURE LEGACY OF STOCKPILE STEWARDSHIP: ISOTOPE PRODUCTION, APPLICATIONS, AND CONSUMPTION LA English DT Proceedings Paper CT 32nd Annual Midyear Topical Meeting of the Health-Physics-Society CY JAN 24-27, 1999 CL ALBUQUERQUE, NM SP Hlth Phys Soc Rio Grande Chapter AB Radiological emergency response planning and support for the 15 October 1997 Cassini Launch from the Eastern Launch Site (Kennedy Space Center/Cape Canaveral Air Station) is reviewed. Space nuclear launches are multiagency efforts and include support and participation from the National Aeronautics and Space Administration, the U.S. Department of Energy, the United States Air Force, the U.S. Environmental Protection Agency, the Federal Emergency Management Agency, and the State and surrounding counties of Florida. Supporting systems and elements, including mobile field radiological monitoring teams, computerized dispersion modeling, airborne monitoring, automated data management, and both active and passive sampling techniques, are described. Communication, command and control, and interagency interfaces are also covered. C1 NASA, Biomed Off, Kennedy Space Ctr, FL 32899 USA. RP Marmaro, GM (reprint author), NASA, Biomed Off, Kennedy Space Ctr, FL 32899 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MEDICAL PHYSICS PUBLISHING PI MADISON PA 4513 VERNON BLVD, MADISON, WI 53705 USA BN 0-944838-88-X PY 1999 BP 145 EP 149 PG 5 WC Nuclear Science & Technology; Physics, Applied; Radiology, Nuclear Medicine & Medical Imaging SC Nuclear Science & Technology; Physics; Radiology, Nuclear Medicine & Medical Imaging GA BM63F UT WOS:000079308800023 ER PT B AU Raj, SV Locci, IE Whittenberger, JD AF Raj, SV Locci, IE Whittenberger, JD BE Mishra, RS Mukherjee, AK Murty, KL TI Development of directionally solidified NiAl alloys for aircraft engine applications SO CREEP BEHAVIOR OF ADVANCED MATERIALS FOR THE 21ST CENTURY LA English DT Proceedings Paper CT Symposium on Creep Behavior of Advanced Materials for the 21st-Century, at the 1999 TMS Annual Meeting CY FEB 28-MAR 04, 1999 CL SAN DIEGO, CA SP Minerals Met & Mat Soc, MPMD Div, Minerals Met & Mat Soc, SMD Div ID ROD-PLATE TRANSITION; MECHANICAL-BEHAVIOR; COMPOSITE; CR AB Binary NiAl has attractive thermophysical properties and excellent oxidation resistance which make it a potential candidate for use as turbine blades and vanes in aircraft gas turbine engines. However, it possesses poor high temperature creep and low temperature fracture resistance properties which have limited its use in these applications. One method for potentially improving these properties is through the use of directional solidification technology. This paper reviews current efforts underway to improve the elevated temperature creep properties of NiAl eutectic alloys. C1 NASA, Lewis Res Ctr, Div Mat, Cleveland, OH 44135 USA. RP Raj, SV (reprint author), NASA, Lewis Res Ctr, Div Mat, MS 24-1,21000 Brookpark Rd, Cleveland, OH 44135 USA. NR 28 TC 8 Z9 8 U1 0 U2 1 PU MINERALS, METALS & MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086-7514 USA BN 0-87339-420-8 PY 1999 BP 295 EP 310 PG 16 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Materials Science, Composites SC Materials Science; Metallurgy & Metallurgical Engineering GA BM94E UT WOS:000080197700026 ER PT B AU Johnson, DL AF Johnson, DL BE Ross, RG TI Thermal performance of the Texas Instruments 1-W linear drive cryocooler SO CRYOCOOLERS 10 LA English DT Proceedings Paper CT 10th International Cryocooler Conference CY MAY 26-28, 1998 CL LOCKHEED MARTIN ADV TECHNOL CTR, MONTEREY, CA HO LOCKHEED MARTIN ADV TECHNOL CTR AB The thermal performance of the Texas Instruments (TI) 1-watt linear drive cryocooler was measured for coldtip temperatures varying from 23 Ii to 130 K over a range of heat reject temperatures (+500C to -54 degreesC), input voltage levels (7 Vrms to 10 Vrms), and operating frequencies (50 Hz to 65 Hz). The cooler was driven with a linear amplifier during performance testing to remove the effects of the cooler drive electronics to better understand cooler operation and thermal performance for a variety of environmental conditions that may be encompassed by different users. The wide heat sink temperature span provided a large variation in the refrigeration capacity of the cooler in terms of both the lowest attainable coldtip temperature and the refrigeration capacity at a given coldtip temperature. Over this large span of heat sink temperatures, the lowest achievable coldtip temperature varied from 45 K to 23 K, while the refrigeration capacity at a given temperature changed by as much as 650 mW. As one example, the refrigeration capacity at 77 K varied from 0.82 watts at +50 degreesC to 1.45 watts at -54 degreesC, with corresponding cooler input power levels of 31 watts and 27 watts, respectively. Additional cooler tests were performed using the TI voltage-mode cooler drive electronics and DC-DC voltage converters to measure the electronics efficiencies in a simulated spacecraft operating mode. The cooler drive electronics was observed to operate with a nominal 70% efficiency, while this particular set of voltage converters operated with an nominal 83% efficiency. The efficiency of the electronics plays a large part in determining the overall spacecraft power requirements to operate the cooler as well as determining the thermal dissipation characteristics of the various electrical components. The results of all the performance measurements are presented in this paper. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnson, DL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA BN 0-306-46120-X PY 1999 BP 95 EP 104 PG 10 WC Thermodynamics SC Thermodynamics GA BR59Y UT WOS:000166912300010 ER PT B AU Ross, RG Johnson, DL Collins, SA Green, K Wickman, H AF Ross, RG Johnson, DL Collins, SA Green, K Wickman, H BE Ross, RG TI AIRS PFM pulse tube cooler system-level performance SO CRYOCOOLERS 10 LA English DT Proceedings Paper CT 10th International Cryocooler Conference CY MAY 26-28, 1998 CL LOCKHEED MARTIN ADV TECHNOL CTR, MONTEREY, CA HO LOCKHEED MARTIN ADV TECHNOL CTR AB JPL's Atmospheric Infrared Sounder (AIRS) instrument is being built to make precision measurements of air temperature over the surface of the Earth as a function of elevation; the flight instrument is in the final stages of assembly and checkout at this time, and uses a pair of TRW pulse tube cryocoolers operating at 55 Ii to cool its sensitive LR focal plane. The cryocooler development activity is a highly collaborative effort involving cooler design and fabrication at TRW, cooler characterization and qualification testing at TRW and JPL, and system-level performance characterization and instrument integration at LMIRIS. During the past few months the Engineering Model AIRS cooler has been integrated with the instrument focal plane assembly and measurements have been made on the overall thermal and operational performance of the cryosystem including vibration compatibility, DeltaT from cooler to focal plane, and temperature control stability. At the same time the AIRS flight (PFM) coolers have undergone qualification and characterization testing at JPL prior to shipment to LMIRIS in January 1998, where they are now undergoing integration and system-level testing with the AIRS flight instrument. This paper presents the measured system-level performance of the AIRS flight coolers including detailed thermal, vibration, and temperature control performance with the EM and flight instrument boundary conditions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ross, RG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 1 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA BN 0-306-46120-X PY 1999 BP 119 EP 128 PG 10 WC Thermodynamics SC Thermodynamics GA BR59Y UT WOS:000166912300013 ER PT B AU Ravikumar, KV Matsubara, Y AF Ravikumar, KV Matsubara, Y BE Ross, RG TI Experimental results of pulse tube cooler with inertance tube as phase shifter SO CRYOCOOLERS 10 LA English DT Proceedings Paper CT 10th International Cryocooler Conference CY MAY 26-28, 1998 CL LOCKHEED MARTIN ADV TECHNOL CTR, MONTEREY, CA HO LOCKHEED MARTIN ADV TECHNOL CTR AB Interest in miniaturization of pulse tube coolers necessitated its operation at higher frequencies where fluid inertia effects start to show significant influence on the performance of the cooler. Commonly used means to achieve optimum performance of the cooler are orifice or capillary tube and double inlet. Fluid inertia at higher frequencies provide another means to achieve optimum performance. This type of phase shifter is referred in literature as "neck-tube" or "inertance tube". Ravikumar and Matsubara [Adv. Cryogenic Eng., Vol. 43] presented experimental results of the cooler using fluid inertia as phase shifter. Their results showed that as frequency increased the "inertance tube" phase shifter enhanced the cooler performance in a region where orifice or double-inlet deteriorated the performance. For similar operating conditions inertance tube phase shifter resulted in higher pressure ratios inside the pulse tube. The fluid inertia is a strong function of inertance tube cross sectional area and length. Further experimental results exploring the dependence of no-load refrigeration temperature and refrigeration load vs refrigeration temperature on frequency of operation, inertance tube diameter and length are presented here. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ravikumar, KV (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA BN 0-306-46120-X PY 1999 BP 291 EP 298 PG 8 WC Thermodynamics SC Thermodynamics GA BR59Y UT WOS:000166912300034 ER PT B AU Hall, JL Ross, RG AF Hall, JL Ross, RG BE Ross, RG TI Gas contamination effects on pulse tube performance SO CRYOCOOLERS 10 LA English DT Proceedings Paper CT 10th International Cryocooler Conference CY MAY 26-28, 1998 CL LOCKHEED MARTIN ADV TECHNOL CTR, MONTEREY, CA HO LOCKHEED MARTIN ADV TECHNOL CTR AB Experiments were performed to quantify the effect of contamination in the helium working gas of a typical pulse tube cryocooler operating at 60 K with 1 W of applied heating load. A quadrupole mass spectrometer with a closed ion source was used to measure the gas compositions both before and after pulse tube operation. Five tests were performed with different combinations of water, carbon dioxide, nitrogen and argon gas contaminating the helium across a range of 20 to 420 parts per million (ppm). Except for hydrogen, no other contaminants were detected in any experiment either before or after running the pulse tube. A decrease in pulse tube refrigeration performance was observed in all five tests, with asymptotic steady-state temperatures reached on a time scale of 7 to 10 days. Under a 1 W applied load condition with a constant piston stroke, the cold head temperature rise ranged from 0.6 to 2.8 K depending on contamination level. Comparisons between cryopumped and non-cryopumped vacuum chambers appeared to rule out the possibility that the contamination was external to the pulse tube. Water and carbon dioxide were the most important contaminants at the nominal operating temperature of 60 K, although there was evidence for nitrogen condensation under some conditions. Warming up of the pulse tube to room temperature tended to restore the original performance, although this improvement degraded more rapidly the second time around to the asymptotic steady-state temperature. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hall, JL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 1 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA BN 0-306-46120-X PY 1999 BP 343 EP 350 PG 8 WC Thermodynamics SC Thermodynamics GA BR59Y UT WOS:000166912300041 ER PT B AU Lee, JM Kittel, P Timmerhaus, KD Radebaugh, R AF Lee, JM Kittel, P Timmerhaus, KD Radebaugh, R BE Ross, RG TI Simple two-dimensional corrections for one-dimensional pulse tube models SO CRYOCOOLERS 10 LA English DT Proceedings Paper CT 10th International Cryocooler Conference CY MAY 26-28, 1998 CL LOCKHEED MARTIN ADV TECHNOL CTR, MONTEREY, CA HO LOCKHEED MARTIN ADV TECHNOL CTR AB One-dimensional oscillating flow models are very useful for designing pulse tubes. They are simple to use, not computationally intensive, and the physical relationship between temperature, pressure and mass flow are easy to understand when described with phasor diagrams. They do not possess, however, the ability to directly calculate thermal and momentum diffusion in the direction transverse to the oscillating flow. To account for transverse diffusion effects, either parameter corrections must be obtained through experimentation, or solutions to the two-dimensional differential fluid equations must be found. A linearized two-dimensional solution to the fluid equations has been obtained. The solution provides lumped parameter corrections for one-dimensional models. The model accounts for heat transfer and shear flow between the gas and the tube wall. The complex Nusselt number and complex shear wall are useful in describing these corrections, with phase relations and amplitudes scaled with the Prandtl and Valensi numbers. The calculated enthalpy flow ratio, a, between a two-dimensional solution of the oscillating temperature and velocity and a one-dimensional solution for the same shows a scales linearly with Va for Va < 30. In this region < 0.5, that is, the enthalpy flow calculated with a two-dimensional model is 50% of a calculation using a one-dimensional model. For Va > 250, alpha = 0.8, showing that diffusion is still important even when it is confined to near the tube wall. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lee, JM (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 4 TC 0 Z9 0 U1 2 U2 2 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA BN 0-306-46120-X PY 1999 BP 351 EP 358 PG 8 WC Thermodynamics SC Thermodynamics GA BR59Y UT WOS:000166912300042 ER PT B AU Roach, PR Helvensteijn, BPM AF Roach, PR Helvensteijn, BPM BE Ross, RG TI Development of a dilution refrigerator for low-temperature microgravity experiments SO CRYOCOOLERS 10 LA English DT Proceedings Paper CT 10th International Cryocooler Conference CY MAY 26-28, 1998 CL LOCKHEED MARTIN ADV TECHNOL CTR, MONTEREY, CA HO LOCKHEED MARTIN ADV TECHNOL CTR AB A dilution refrigerator (DR) is the most common precooling stage for sub-millikelvin demagnetization experiments. The usefulness of the DR comes from its ability to provide cooling at 0.02-0.04 K for long periods of time while the heat of magnetization is being rejected by the demagnetization stage. In order to make these advantages of the DR available to researchers who need the microgravity of space for their experiments, we are developing a continuously-operating DR that will function in microgravity. We have previously demonstrated that the liquid helium of the DR can be controlled by the use of capillary forces in sintered metal sponges. We have found, however, that the small pores needed to control large heights of liquid on the ground are too small to allow sufficient liquid flow for effective cooling. We have built a shallow single-cycle version of the refrigerator that does not require large heights of liquid to be supported by capillary forces. The liquid chambers are next to each other and are filled with sinter with relatively open pores; these pores will allow much freer flow of the helium. The gravity independence of this design will be tested by tilting the system so that one chamber is slightly above or below the other and by inverting both chambers. The operation of the refrigerator should be unaffected by tilts of 5-10 degrees or by the inversion of the chambers. A design for a continuously-operating dilution refrigerator is presented. It includes all the advantages of the single-cycle refrigerator while adding the large advantage of continuous cooling for long periods of time. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Roach, PR (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA BN 0-306-46120-X PY 1999 BP 647 EP 653 PG 7 WC Thermodynamics SC Thermodynamics GA BR59Y UT WOS:000166912300077 ER PT B AU Johnson, DL Collins, SA Ross, RG AF Johnson, DL Collins, SA Ross, RG BE Ross, RG TI EMI performance of the AIRS cooler and electronics SO CRYOCOOLERS 10 LA English DT Proceedings Paper CT 10th International Cryocooler Conference CY MAY 26-28, 1998 CL LOCKHEED MARTIN ADV TECHNOL CTR, MONTEREY, CA HO LOCKHEED MARTIN ADV TECHNOL CTR AB The TRW pulse tube cryocooler for JPL's Atmospheric Infrared Sounder (AIRS) instrument is required to meet stringent requirements for radiated electric and magnetic fields, conducted emissions on the input power bus, and electromagnetic susceptibility. To meet the radiated magnetic field requirements, special mu-metal shields were designed, fabricated, and fitted to the cooler following an extensive period of magnetic testing with mock-up cooler hardware. Excessive magnetic fields is a generic issue with linear-motor cryocoolers, as is excessive levels of input ripple current. Solving the ripple current issue required the addition of a dedicated ripple filter as part of the spacecraft power system. As one of the first cryocoolers with flight electronics available for testing, the AIRS cooler offered an important opportunity to measure and understand these important issues. This paper describes the development of the magnetic shields to bring the AC magnetic fields of the AIRS cooler within the requirements of Mn-STD-461C, includes before and after data on the achieved field levels, and presents extensive data on the suite of EMI characteristics of the AIRS cooler with its flight electronics. Because of its importance, levels of input ripple current are presented as a function of compressor input power to allow future applications to judge the ripple-current compatibility with specific power system capabilities and to serve as data for scoping the design of ripple suppression hardware. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnson, DL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 0 Z9 0 U1 0 U2 1 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA BN 0-306-46120-X PY 1999 BP 771 EP 780 PG 10 WC Thermodynamics SC Thermodynamics GA BR59Y UT WOS:000166912300090 ER PT B AU Kittel, P Salerno, LJ Plachta, DW AF Kittel, P Salerno, LJ Plachta, DW BE Ross, RG TI Cryocoolers for human and robotic missions to Mars SO CRYOCOOLERS 10 LA English DT Proceedings Paper CT 10th International Cryocooler Conference CY MAY 26-28, 1998 CL LOCKHEED MARTIN ADV TECHNOL CTR, MONTEREY, CA HO LOCKHEED MARTIN ADV TECHNOL CTR AB Future missions to Mars will make use of a number of different cryocoolers. These cryocoolers will be used to liquefy and preserve propellants and for transporting liquid hydrogen feed stock. The earliest mission requiring a cryocooler is the 2003 robotic mission, which will demonstrate technology for In-Situ-Consumable-Production (ISCP) as part of the long-term goal of developing In-Situ-Resource-Utilization (ISRU). Later missions may require cryocoolers to preserve propellants on Trans-Mars Injection stages, Martian landers, and Mars return vehicles. In addition, ISCP may require liquid hydrogen feed stock as part of the chemical process to produce propellants from the Martian atmosphere. Cryocoolers will be required to minimize or eliminate the boiloff of this hydrogen in transit to Mars. Propellants produced on Mars will need liquefiers and cryocoolers for storage on the Martian surface until the propellants are used in the ascent vehicle. This paper will present a description of the planned missions with an emphasis on the various cryogenic options being considered and on current estimates of cooling requirements. These estimates are continuing to evolve. They are based on ongoing design and trade-off studies. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kittel, P (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA BN 0-306-46120-X PY 1999 BP 815 EP 821 PG 7 WC Thermodynamics SC Thermodynamics GA BR59Y UT WOS:000166912300096 ER PT J AU Benford, DJ Powers, TJ Moseley, SH AF Benford, DJ Powers, TJ Moseley, SH TI Thermal conductivity of Kapton tape SO CRYOGENICS LA English DT Article DE thermal conductivity; Kapton; polyimide film ID FILM AB Measurements of the thermal conductivity of Kapton tape at temperatures between 5 and 300 K are reported in this technical note. This material is useful for making low-conductance cryogenic ribbon cables. The thermal conductivity along the length of Kapton tape was found to be 5.24 x 10(-3)T(1.02) W m(-1) K-1. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Benford, DJ (reprint author), CALTECH, MC 320-47, Pasadena, CA 91125 USA. RI Benford, Dominic/D-4760-2012; Moseley, Harvey/D-5069-2012 OI Benford, Dominic/0000-0002-9884-4206; NR 5 TC 15 Z9 16 U1 5 U2 13 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD JAN PY 1999 VL 39 IS 1 BP 93 EP 95 DI 10.1016/S0011-2275(98)00125-8 PG 3 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 183FL UT WOS:000079543500012 ER PT J AU Grasza, K Palosz, W AF Grasza, K Palosz, W TI Some aspects of PVT low-supersaturation nucleation and contactless crystal growth SO CRYSTAL RESEARCH AND TECHNOLOGY LA English DT Article; Proceedings Paper CT 5th Polish Conference on Crystal Growth (PCCG-V) CY MAY 10-13, 1998 CL NALECZOW, POLAND SP Polish Minist Higher Educ, State Comm Scientif Res DE theory and modeling of crystal growth; growth from the vapor; computational modeling; cadmium telluride ID VAPOR AB The basic principles of the contactless growth of crystals from the vapor in combination with the process of low-supersaturation nucleation are discussed. The mathematical formulation of the morphological stability criterion in vapor growth systems is given and its implications for contactless growth technique are analysed. A diagram for selection of proper temperature conditions for growth of CdTe crystals is presented. C1 Polish Acad Sci, Inst Phys, PL-02668 Warsaw, Poland. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. RP Grasza, K (reprint author), Polish Acad Sci, Inst Phys, Al Lotnikow 32-46, PL-02668 Warsaw, Poland. NR 5 TC 7 Z9 7 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 0232-1300 J9 CRYST RES TECHNOL JI Cryst. Res. Technol. PY 1999 VL 34 IS 5-6 BP 565 EP 571 DI 10.1002/(SICI)1521-4079(199906)34:5/6<565::AID-CRAT565>3.0.CO;2-X PG 7 WC Crystallography SC Crystallography GA 212BG UT WOS:000081196000004 ER PT S AU Waluschka, E AF Waluschka, E BE Fischer, RE Smith, WJ TI LISA far field phase patterns SO CURRENT DEVELOPMENTS IN OPTICAL DESIGN AND OPTICAL ENGINEERING VIII SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 8th Conference on Current Developments in Optical Design and Optical Engineering CY JUL 19-21, 1999 CL DENVER, CO SP SPIE DE Gravitational Waves; interferometry; space; optics; Zernike AB The Laser Interferometry Space Antenna (LISA) for the detection of Gravitational Waves is a very long baseline interferometer that will measure the changes in the distance of a five million kilometer arm to pico meter accuracies. Knowledge of the phase deviations from a spherical wave and what causes these deviations are needed considerations in las a minimum) the design of the telescope and in determining pointing requirements. Here we present the far field phase deviations from a spherical wave for given Zernike aberrations and obscurations of the exit pupil. C1 NASA, Goddard Space Flight Ctr 5510, Greenbelt, MD 20771 USA. RP Waluschka, E (reprint author), NASA, Goddard Space Flight Ctr 5510, Greenbelt, MD 20771 USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3265-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3779 BP 31 EP 39 DI 10.1117/12.368217 PG 9 WC Engineering, Multidisciplinary; Optics SC Engineering; Optics GA BN97X UT WOS:000083738800004 ER PT S AU Alexander, CD Swift, W Ghosh, K Ramsey, B AF Alexander, CD Swift, W Ghosh, K Ramsey, B BE Fischer, RE Smith, WJ TI Design of a day/night star camera system SO CURRENT DEVELOPMENTS IN OPTICAL DESIGN AND OPTICAL ENGINEERING VIII SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 8th Conference on Current Developments in Optical Design and Optical Engineering CY JUL 19-21, 1999 CL DENVER, CO SP SPIE DE star camera; aspect system; stratospheric balloon flights; daytime star camera; R band AB This paper describes the design of a camera system capable of acquiring stars during both the day and night cycles of a high altitude balloon flight (35-42 km). The camera system will be filtered to operate in the R and I bands (similar to 600-1000nm), and simulations have been run using MODTRAN atmospheric code to determine the worse case sky brightness at 35km. With a worse case daytime sky brightness of 2x10(-5) W/cm(2)/sr/mu m at 600nm, the sensitivity of the camera system will allow acquisition of at least 1-2 stars/degrees(2) at star magnitude limits of 7.8-8.1. The system will have an F2.8, 64.3mm diameter lens and a 1340 x 1037 CCD digitized to 12 bits. The CCD is comprised of 6.8 mu m x 6.8 mu m pixels with a well depth of 45,000 electrons and quantum efficiency of 0.54 at 700nm. The camera's field-of-view will be 6.33 degrees(2) and provide attitude knowledge to 8 arcsec or better. A test flight of the system is scheduled for fall 1999. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. RP Alexander, CD (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. NR 4 TC 4 Z9 4 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3265-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3779 BP 47 EP 54 DI 10.1117/12.368236 PG 8 WC Engineering, Multidisciplinary; Optics SC Engineering; Optics GA BN97X UT WOS:000083738800006 ER PT S AU Smialek, JL Nesbitt, JA Barrett, CA Lowell, CE AF Smialek, JL Nesbitt, JA Barrett, CA Lowell, CE BE Schutze, M Quadakkers, WJ TI Cyclic oxidation testing and modelling: a NASA Lewis perspective SO CYCLIC OXIDATION OF HIGH TEMPERATURE MATERIALS: MECHANISMS, TESTING METHODS, CHARACTERISATION AND LIFE TIME ESTIMATION SE EUROPEAN FEDERATION OF CORROSION PUBLICATIONS LA English DT Proceedings Paper CT European-Federation-of-Corrosion Workshop on Cyclic Oxidation Testing as a Tool for High Temperature Materials Characterisation CY FEB 25-26, 1999 CL DECHEMA EV, KARL WINNACKER INST, FRANKFURT, GERMANY SP European Federat Corros HO DECHEMA EV, KARL WINNACKER INST ID CR; ALLOYS; AL; SUPERALLOYS; RESISTANCE; BEHAVIOR AB The Materials Division of the NASA Lewis Research Center has been heavily involved in the cyclic oxidation of high temperature materials for 30 years. Cyclic furnace and burner rig apparatuses have been developed, refined, and replicated to provide a large scale facility capable of evaluating many materials by a standard technique. Material behaviour is characterised by mass change data obtained throughout the test, which has been modelled in a step-wise process of scale growth and spallation. This model and a coupled diffusion model have successfully described cyclic behaviour for a number of systems and have provided insights regarding Life prediction and variations in the spalling process. Performance ranking and mechanistic studies are discussed primarily for superalloys and coating alloys. Similar cyclic oxidation studies have been performed on steels, intermetallic compounds, thermal barrier coatings, ceramics, and ceramic composites. The most common oxidation test was performed in air at temperatures ranging from 800 degrees to 1600 degreesC, for times up to 10 000 h, and for cycle durations of 0.1 to 1000 h. Less controlled, but important, test parameters are the cooling temperature and humidity level. Heating and tooling rates are not likely to affect scale spallation. Broad experience has usually allowed for considerable focus and simplification of these test parameters, while still revealing the principal aspects of material behavior and performance. Extensive testing has been performed to model statistically the compositional effects of experimental alloys and to construct a comprehensive database of complex commercial alloys. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Smialek, JL (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 32 TC 13 Z9 13 U1 0 U2 0 PU IOM COMMUNICATIONS LTD PI LONDON PA 1 CARLTON HOUSE TERRACE, LONDON SW1Y 5DB, ENGLAND SN 1354-5116 BN 1-86125-100-9 J9 EUR FED CORR PUBL PY 1999 IS 27 BP 148 EP 168 PG 21 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA BR73C UT WOS:000167358300009 ER PT S AU Sirkis, J Childers, B Melvin, L Peng, T Tang, Y Moore, J Enright, E Bovier, C AF Sirkis, J Childers, B Melvin, L Peng, T Tang, Y Moore, J Enright, E Bovier, C BE Gilchrist, MD DulieuBarton, JM Worden, K TI Integrated vehicle health management (IVHM) on space vehicles: A space shuttle flight experiment SO DAMAS 99: DAMAGE ASSESSMENT OF STRUCTURES SE KEY ENGINEERING MATERIALS LA English DT Article; Proceedings Paper CT 3rd International Conference on Damage Assessment of Structures (DAMAS 99) CY JUN 28-30, 1999 CL DUBLIN, IRELAND DE launch vehicles; integrated vehicle health management; fiber optic sensors; distributed strain sensors; distributed temperature sensors; distributed hydrogen sensors; NASA space shuttle; X-33; Bragg grating sensors; Raman sensors ID OPTICAL-FIBER; DISTRIBUTED MEASUREMENT; BRAGG GRATINGS; STRAIN; SYSTEM AB This paper describes ongoing programs to develop fiber optic-based integrated vehicle health management (IVHM) systems for the NASA Space Shuttle and the Lockheed Martin X-33 reusable launch vehicle demonstrator, System requirements for IVHM systems are covered, followed by a descriptions of the strain, temperature and hydrogen sensors systems making up the IVHM system, and finally test and verification data is described. Data from the launch of the NASA Space Shuttle will be presented at the conference. C1 Univ Maryland, Smart Mat & Struct Res Ctr, College Pk, MD 20742 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Michoud Space Syst, New Orleans, LA USA. RP Sirkis, J (reprint author), Univ Maryland, Smart Mat & Struct Res Ctr, College Pk, MD 20742 USA. NR 14 TC 0 Z9 0 U1 1 U2 1 PU TRANSTEC PUBLICATIONS LTD PI ZURICH-UETIKON PA BRANDRAIN 6, CH-8707 ZURICH-UETIKON, SWITZERLAND SN 1013-9826 BN 0-87849-839-7 J9 KEY ENG MAT PY 1999 VL 167-1 BP 273 EP 280 PG 8 WC Materials Science, Ceramics; Materials Science, Composites; Physics, Atomic, Molecular & Chemical SC Materials Science; Physics GA BN65P UT WOS:000082483600027 ER PT J AU Gomez, F Segami, C Delaune, C AF Gomez, F Segami, C Delaune, C TI A system for the semiautomatic generation of E-R models from natural language specifications SO DATA & KNOWLEDGE ENGINEERING LA English DT Article DE automated logical database design; natural language; rule-based system AB Techniques that allow a program to generate E-R models for small application domains are described. The inputs to the program are natural language specifications. The program consists of two major components: a natural language understander and an E-R generator. The paper describes briefly the knowledge representation structures constructed by the natural language understander, and, then, explains the E-R generator in detail. The E-R generator consists of two kinds of rules: specific rules linked to the semantics of some words in the sentences, and generic rules that identify ER-entities and ER-relationships on the basis of the logical form of the sentence and on the basis of the ER-entities and ER-relationships under construction. The program has been tested on a set of database problems. (C) 1999 Elsevier Science B.V. All rights reserved. C1 Univ Cent Florida, Sch Comp Sci, Orlando, FL 32816 USA. Barry Univ, Dept Math & Comp Sci, Miami, FL 33161 USA. NASA, Kennedy Space Ctr, FL 32899 USA. RP Gomez, F (reprint author), Univ Cent Florida, Sch Comp Sci, Orlando, FL 32816 USA. NR 28 TC 13 Z9 14 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-023X J9 DATA KNOWL ENG JI Data Knowl. Eng. PD JAN PY 1999 VL 29 IS 1 BP 57 EP 81 DI 10.1016/S0169-023X(98)00032-9 PG 25 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems SC Computer Science GA 156KZ UT WOS:000078001400004 ER PT S AU Burl, MC Fowlkes, C Roden, J Stechert, A Mukhtar, S AF Burl, MC Fowlkes, C Roden, J Stechert, A Mukhtar, S BE Dasarathy, BV TI Diamond eye: A distributed architecture for image data mining SO DATA MINING AND KNOWLEDGE DISCOVERY: THEORY, TOOLS, AND TECHNOLOGY SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Data Mining and Knowledge Discovery - Theory, Tools, and Technology CY APR 05-06, 1999 CL ORLANDO, FL SP SPIE - Int Soc Opt Engn DE image collections; mining; distributed systems; software; infrastructure; architecture; search; client-server; Java; database exploration AB Diamond Eye is a distributed software architecture that enables users (scientists) to analyze large image collections by interacting with one or more custom data mining servers via a Java applet interface. Each server is coupled with an object-oriented database and a computational engine such as a network of high-performance workstations. The database provides persistent storage and supports querying of the "mined" information. The computational engine provides parallel execution of expensive image processing, object recognition,and query-by-content operations. Key benefits of the Diamond Eye architecture are: (1) the design promotes trial evaluation of advanced data mining and machine learning techniques by potential new users (all that is required is to point a web browser to the appropriate URL), (2) software infrastructure that is common across a range of science mining applications is factored out and reused, and (3) the system facilitates closer collaborations between algorithm developers and domain experts. C1 Jet Propuls Lab, Pasadena, CA 91109 USA. RP Burl, MC (reprint author), Jet Propuls Lab, 4800 Oak Grove Dr,MS 126-347, Pasadena, CA 91109 USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3169-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3695 BP 197 EP 206 DI 10.1117/12.339982 PG 4 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems; Computer Science, Interdisciplinary Applications; Optics SC Computer Science; Optics GA BM94P UT WOS:000080212300021 ER PT J AU Toudal, L Hansen, KQ Valeur, H Wadhams, P Aldworth, E Comiso, JC AF Toudal, L Hansen, KQ Valeur, H Wadhams, P Aldworth, E Comiso, JC TI Mapping of ice in the Odden by satellite and airborne remote sensing SO DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY LA English DT Article ID SEA ICE; MICROWAVE AB A detailed analysis of the ice conditions in the Odden area of the Greenland Sea was carried out using data from active and passive microwave sensors, supplemented by airborne data. The study focuses on the 1992-1993 winter season, the only winter during the period 1993-1995 in which an Odden feature formed. The analysis is structured as a hierarchy of spatial resolutions where the overview is obtained by the DMSP SSM/I microwave radiometers having spatial resolutions in the 15-50 km range. Further details in cloud-free situations are obtained by data from the NOAA advanced very high resolution radiometer, which is a scanner in the visible, near-infrared and thermal infrared range with a resolution of 1.1 km. The finest resolution of 25 m per pixel is obtained from the synthetic aperture radar on the ERS-1 satellite. (C) 1999 Elsevier Science Ltd. All rights reserved. C1 Tech Univ Denmark, Danish Ctr Remote Sensing, DK-2800 Lyngby, Denmark. Danish Meteorol Inst, DK-210 Copenhagen, Denmark. Univ Cambridge, Scott Polar Res Inst, Cambridge CB2 1ER, England. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Toudal, L (reprint author), Tech Univ Denmark, Danish Ctr Remote Sensing, Bldg 348, DK-2800 Lyngby, Denmark. NR 21 TC 5 Z9 6 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0967-0645 J9 DEEP-SEA RES PT II JI Deep-Sea Res. Part II-Top. Stud. Oceanogr. PY 1999 VL 46 IS 6-7 BP 1255 EP 1274 DI 10.1016/S0967-0645(99)00022-3 PG 20 WC Oceanography SC Oceanography GA 210TZ UT WOS:000081121900009 ER PT S AU Hartley, FT Malek, CK AF Hartley, FT Malek, CK BE Courtois, B Demidenko, S TI Nanometer X-ray lithography SO DESIGN, CHARACTERIZATION, AND PACKAGING FOR MEMS AND MICROELECTRONICS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Design, Characterization, and Packaging for MEMS and Microelectronics CY OCT 27-29, 1999 CL QUEENSLAND, AUSTRALIA SP SPIE, IREE Soc, Queensland Govt State Dev, Griffith Univ Microelectr Engn Soc, Australia, IEEE, Electron Devices Soc, Electrochem Soc DE X-rays; lithography on non-planar surfaces; conformal coating; large depth-of-field; nanolithography ID PHOTORESIST AB New developments for X-ray nanomachining include pattern transfer onto non-planar surfaces coated with electrodeposited resists using synchrotron radiation X-rays through extremely high-resolution masks made by chemically assisted focused ion beam lithography. Standard Ultraviolet (UV) photolithographic processes cannot maintain sub-micron definitions over large variation in feature topography. The ability of X-ray printing to pattern thin or thick layers of photoresist with high resolution on non-planar surfaces of large and complex topographies with limited diffraction and scattering effects and no substrate reflection is known and can be exploited for patterning microsystems with non-planar 3-D geometries as well as multisided and multilayered substrates. Thin conformal coatings of electro-deposited positive and negative tone photoresists have been shown to be X-ray sensitive and accommodate sub-micron pattern transfer over surfaces of extreme topographical variations (over 100 microns). Chemically assisted focused ion beam selective anisotropic erosion was used to fabricate Xray masks directly. Masks with feature sizes less than 20 nm through 7 microns of gold (aspect ratio similar to 350) were made on bulk silicon substrates and X-ray mask membranes. The technique is also applicable to other high density materials. Such masks enable the primary and secondary patterning and/or 3D machining of Nano-Electro-Mechanical Systems (NEMS)s over large depths or complex relief and the patterning of large surface areas with sub-optically dimensioned features. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hartley, FT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 24 TC 1 Z9 1 U1 1 U2 2 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3494-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3893 BP 48 EP 58 DI 10.1117/12.368464 PG 11 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Materials Science, Characterization & Testing; Optics SC Engineering; Materials Science; Optics GA BP26M UT WOS:000084509900006 ER PT S AU Miller, LM AF Miller, LM BE Courtois, B Crary, SB Ehrfeld, W Fujita, H Karam, JM Markus, K TI MEMS for space applications SO DESIGN, TEST, AND MICROFABRICATION OF MEMS AND MOEMS, PTS 1 AND 2 SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Design, Test, and Microfabrication of MEMS and MOEMS CY MAR 30-APR 01, 1999 CL PARIS, FRANCE SP SPIE, CNRS, INPG, UIF, France, IEEE Comp Soc Test Technol Tech Comm DE MEMS; Space Applications; Review; Mars Microprobe; microgyroscope; system-on-a-chip AB Phenomenal advances in MicroElectroMechanical Systems (MEMS) performance has made this technology attractive for the development of micro- and nano-spacecraft. However, much work remains to be done. The space environment is harsh: extreme heat and cold, thermal cycling, radiation effects, and corrosive environments put conventional device designs at risk. Reliability, packaging and flight qualification methodologies need to be developed for MEMS to produce robust devices for a successful future in space micromissions. These issues are discussed in this paper, along with examples of micromissions, MEMS devices in development for space applications, and the ultimate in device integration: a System-On-A-Chip (SOAC). C1 CALTECH, Jet Prop Lab, MicroDevices Lab, Pasadena, CA 91109 USA. RP Miller, LM (reprint author), CALTECH, Jet Prop Lab, MicroDevices Lab, 4800 Oak Grove Dr,MS 302-306, Pasadena, CA 91109 USA. NR 23 TC 2 Z9 2 U1 2 U2 3 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3154-0 J9 P SOC PHOTO-OPT INS PY 1999 VL 3680 BP 2 EP 11 DI 10.1117/12.341193 PN 1&2 PG 10 WC Engineering, Manufacturing; Engineering, Electrical & Electronic; Engineering, Mechanical; Optics SC Engineering; Optics GA BN52D UT WOS:000082111700001 ER PT S AU Fijany, A Collier, JB Citak, A AF Fijany, A Collier, JB Citak, A BE Dubey, AC Harvey, JF Broach, JT Dugan, RE TI Advanced algorithms and high performance testbed for large scale site characterization and subsurface target detection using airborne ground penetrating SAR SO DETECTION AND REMEDIATION TECHNOLOGIES FOR MINES AND MINELIKE TARGETS IV, PTS 1 AND 2 SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Detection and Remediation Technologies for Mines and Minelike Targets IV Conference CY APR 05-09, 1999 CL ORLANDO, FL SP SPIE DE ground penetrating radar; unexploded ordnance; SAR; UXO detection AB A team of US Army Corps of Engineers, Omaha District and Engineering and Support Center, Huntsville, Jet Propulsion Laboratory (JPL), Stanford Research Institute (SRI), and Montgomery Watson is currently in the process of planning and conducting the largest ever survey at the Former Buckley Field (60,000 acres), in Colorado, by using SRI airborne, ground penetrating, Synthetic Aperture Radar (SAR). The purpose of this survey is the detection of surface and subsurface Unexploded Ordnance (UXO) and in a broader sense the site characterization for identification of contaminated as well as clear areas. In preparation for such a large-scale survey, JPL has been developing advanced algorithms and a high-performance testbed for processing of massive amount of expected SAR data from this sire. Two key requirements of this project are the accuracy tin terms of UXO detection) and speed of SAR data processing. The first key feature of this testbed is a large degree of automation and a minimum degree of the need for human perception in the processing to achieve an acceptable processing rate of several hundred acres per day. For accurate UXO detection, novel algorithms have been developed and implemented, These algorithms analyze dual polarized (HH and VV) SAR data. They are based on the correlation of HH and VV SAR data and involve a rather large set of parameters for accurate detection of UXO. For each specific site, this set of parameters can be optimized by using ground truth data (i.e., known surface and subsurface UXOs). In this paper, we discuss these algorithms and their successful application for detection of surface and subsurface anti-tank mines by using a data set from Yuma proving Ground, AZ, acquired by SRI SAR. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fijany, A (reprint author), CALTECH, Jet Prop Lab, MS 126-347,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 1 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3184-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3710 BP 1106 EP 1117 DI 10.1117/12.356991 PN 1&2 PG 12 WC Engineering, Electrical & Electronic; Instruments & Instrumentation; Optics SC Engineering; Instruments & Instrumentation; Optics GA BN59G UT WOS:000082322300109 ER PT S AU Hartley, FT Malek, CK AF Hartley, FT Malek, CK BE Chau, K Dimitrijev, S TI Nanometer X-ray lithography SO DEVICE AND PROCESS TECHNOLOGIES FOR MEMS AND MICROELECTRONICS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Device and Process Technologies for MEMS and Microelectronics CY OCT 27-29, 1999 CL QUEENSLAND, AUSTRALIA SP SPIE, IREE Soc, Queensland Govt State Dev, Griffith Univ Microelectr Engn Soc, Australia, IEEE, Electron Devices Soc, Electrochem Soc DE X-rays; lithography on non-planar surfaces; conformal coating; large depth-of-field; nanolithography ID PHOTORESIST AB New developments for X-ray nanomachining include pattern transfer onto non-planar surfaces coated with electrodeposited resists using synchrotron radiation X-rays through extremely high-resolution masks made by chemically assisted focused ion beam lithography. Standard Ultraviolet (UV) photolithographic processes cannot maintain sub-micron definitions over large variation in feature topography. The ability of X-ray printing to pattern thin or thick layers of photoresist with high resolution on non-planar surfaces of large and complex topographies with limited diffraction and scattering effects and no substrate reflection is known and can be exploited for patterning microsystems with non-planar 3-D geometries as well as multisided and multilayered substrates. Thin conformal coatings of electro-deposited positive and negative tone photoresists have been shown to be X-ray sensitive and accommodate sub-micron pattern transfer over surfaces of extreme topographical variations lover 100 microns). Chemically assisted focused ion beam selective anisotropic erosion was used to fabricate Xray masks directly. Masks with feature sizes less than 20 nm through 7 microns of gold (aspect ratio similar to 350) were made on bulk silicon substrates and X-ray mask membranes. The technique is also applicable to other high density materials. Such masks enable the primary and secondary patterning and/or 3D machining of Nano-Electro-Mechanical Systems (NEMS)s over large depths or complex relief and the patterning of large surface areas with sub-optically dimensioned features. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hartley, FT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 24 TC 4 Z9 4 U1 0 U2 2 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3493-0 J9 P SOC PHOTO-OPT INS PY 1999 VL 3892 BP 69 EP 79 PG 11 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Optics SC Engineering; Materials Science; Optics GA BP26L UT WOS:000084509800008 ER PT J AU Prentice, AJR AF Prentice, AJR TI Origin, bulk chemical composition and physical structure of the Galilean satellites of Jupiter: A post-Galileo analysis SO EARTH MOON AND PLANETS LA English DT Review ID DIFFERENTIATED INTERNAL STRUCTURE; ICY SATELLITES; MAGNETIC-FIELD; SOLAR-SYSTEM; SILICATE FRACTIONATION; GRAVITY-FIELD; GANYMEDE; CALLISTO; IO; EVOLUTION AB The origin of Jupiter and the Galilean satellite system is examined in the light of the new data that has been obtained by the NASA Galileo Project. In particular, special attention is given to a theory of satellite origin which was put forward at the start of the Galileo Mission and on the basis of which several predictions have now been proven successful (Prentice, 1996a-c). These predictions concern the chemical composition of Jupiter's atmosphere and the physical structure of the satellites. According to the proposed theory of satellite origin, each of the Galilean satellites formed by chemical condensation and gravitational accumulation of solid grains within a concentric family of orbiting gas rings. These rings were cast off equatorially by the rotating proto-Jovian cloud (PJC) which contracted gravitationally to form Jupiter some 4 1/2 billion years ago. The PJC formed from the gas and grains left over from the gas ring that had been shed at Jupiter's orbit by the contracting proto-solar cloud (PSC). Supersonic turbulent convection provides the means for shedding discrete gas rings. The temperatures T-n of the system of gas rings shed by the PSC and PJC vary with their respective mean orbital radii R-n (n = 0, 1, 2, ... ) according as T-n proportional to R-n(-0.9). If the planet Mercury condenses at 1640 K, so accounting for the high density of that planet via a process of chemical fractionation between iron and silicates, then T-n at Jupiter's orbit is 158 K. Only 35% of the water vapour condenses out. Thus fractionation between rock and ice, together with an enhancement in the abundance of solids relative to gas which takes place through gravitational sedimentation of solids onto the mean orbit of the gas ring, ensures nearly equal proportions of rock and ice in each of Ganymede and Callisto. Io and Europa condense above the H2O ice point and consist solely of hydrated rock (h-rock). The Ganymedan condensate consists of h-rock and H2O ice. For Callisto, NH3 ice makes up approximate to5% of the condensate mass next to h-rock (approximate to 50%) and H2O ice (similar to 45%). Detailed thermal and structural models for each of Europa, Ganymede and Callisto are constructed on the basis of the above initial bulk chemical compositions. For Europa (E), a predicted 2-zone model consisting of a dehydrated rock core of mass 0.912M(E) and a 150 km thick frozen mantle of salty H2O yields a moment-of-inertia coefficient which matches the Galileo Orbiter gravity measurement. For Ganymede (G), a 3-zone model possessing an inner core of solid FeS and mass similar to0.116M(G), and an outer H2O ice mantle of mass similar to0.502M(G) is needed to explain the gravity data. Ganymede's native magnetic field was formed by thermoremanent magnetization of Fe3O4. A new Callisto (C) model is proposed consisting of a core of mass 0.826M(C) containing a uniform mixture of h-rock (60% by mass) and H2O and NH3 ices, and capped by a mantle of pure ice. This model may have the capacity to yield a thin layer of liquid NH3. 2H(2)O at the core boundary, in line with Galileo's discovery of an induced magnetic field C1 Monash Univ, Dept Math & Stat, Clayton, Vic 3800, Australia. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Prentice, AJR (reprint author), Monash Univ, Dept Math & Stat, Clayton, Vic 3800, Australia. NR 109 TC 1 Z9 1 U1 1 U2 4 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PY 1999 VL 87 IS 1 BP 11 EP 55 DI 10.1023/A:1010692812892 PG 45 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 460AT UT WOS:000170284200002 ER PT J AU Sekanina, Z AF Sekanina, Z TI A determination of the nuclear size of comet Hale-Bopp (C/1995 O1) SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT 1st International Conference on Comet Hale-Bopp CY FEB 02-05, 1998 CL TENERIFE, SPAIN DE comet Hale-Bopp; deconvolution technique; nuclear magnitude; nuclear size AB The signal of the nucleus was digitally extracted from six images of the innermost coma of this comet, obtained with the Hubble Space Telescope's Wide-Field Planetary Camera 2 in the planetary mode between October 23, 1995 and October 17, 1996. Two different anisotropic, power-type laws were used to filter out the contribution from the dust coma: one peaking at the center of the elliptical surface brightness distribution (law A), the other peaking at its focus (law B). The nuclear R magnitudes in the Cousins system, reduced to a zero phase angle and to 1 AU from Earth and the Sun with a phase coefficient of 0.035 mag/deg and an inverse square distance power law, are found to average 9.46 +/- 0.07 and 9.48 +/- 0.18 when law A and law B are applied, respectively. These results become 9.49 +/- 0.07 and 9.51 +/- 0.17, when the nucleus signal on the October 1995 image is assumed to consist of a sum of the contributions from two unresolved nuclear components. In either scenario, no systematic variations are apparent in the nuclear brightness with time, which suggests the absence of any significant contamination of the extracted nuclear signal by the coma. Assuming a geometric albedo of 4 percent, the corresponding effective nuclear diameter amounts to 71 +/- 4 km (formal error). This result substantially exceeds the size estimates published by Weaver et al., which are based only on the October 1995 observation and which were obtained with the help of a different reduction method. Runs in which a power-type law fitting the contribution from the coma was assumed to hold all the way to a small fraction of a pixel from the nucleus led to distinctly inferior solutions and yielded spurious values much less than 70 km for the nuclear diameter. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Sekanina, Z (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 3 TC 14 Z9 14 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PY 1999 VL 77 IS 3 BP 147 EP 153 DI 10.1023/A:1006270428595 PG 7 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 249RQ UT WOS:000083346400003 ER PT J AU Sekanina, Z AF Sekanina, Z TI Detection of a satellite orbiting the nucleus of comet Hale-Bopp (C/1995 O1) SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT 1st International Conference on Comet Hale-Bopp CY FEB 02-05, 1998 CL TENERIFE, SPAIN DE comet Hale-Bopp; orbiting satellite; nuclear size; sphere of action AB This paper reports on the detection of a satellite around the principal nucleus of comet Hale-Bopp. As shown elsewhere, a successful morphological model for the comet's dust coma necessitates the postulation of overlapping jet activity from a comet pair. The satellite has been detected digitally on images taken with the Hubble Space Telescope's Wide Field Planetary Camera 2 in the planetary mode on five days in May-October 1996. An average satellite-to-primary signal ratio is 0.21 +/- 0.03, which implies that the satellite is similar to 30 km in diameter, assuming the main nucleus is similar to 70 km across. To avoid collision, the separation distance must exceed 50-60 km at all times. The satellite's projected distances on the images vary from 160 to 210 km, or 0.06 to 0.10 arcsec. The satellite was not detected in October 1995, presumably because of its subpixel separation from the primary. The radius of the gravitational sphere of action of the principal nucleus 70 km in diameter is 370-540 km at perihelion, increasing linearly with the Sun's distance: the satellite appears to be in a fairly stable orbit. Its orbital period at similar to 180 km is expected to be similar to 2-3 days, much shorter than the intervals between the HST observations. If the main nucleus should be no more than 42 km across, Weaver et al.'s upper limit, the satellite's orbit could become unstable, with the object drifting away from the main nucleus after perihelion. Potentially relevant ground-based detections of close companions are reported. Efforts to determine the satellite's orbit and the total mass of the system will get under way in the near future. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Sekanina, Z (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PY 1999 VL 77 IS 3 BP 155 EP 163 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 249RQ UT WOS:000083346400004 ER PT J AU Lisse, CM Dennerl, K Englhauser, J Trumper, J Marshall, FE Petre, R Valinia, A Kellett, BJ Bingham, R AF Lisse, CM Dennerl, K Englhauser, J Trumper, J Marshall, FE Petre, R Valinia, A Kellett, BJ Bingham, R TI X-ray emission from comet Hale-Bopp SO EARTH MOON AND PLANETS LA English DT Article; Proceedings Paper CT 1st International Conference on Comet Hale-Bopp CY FEB 02-05, 1998 CL TENERIFE, SPAIN DE comets : individual; X-rays : solar system AB The discovery of X-ray emission from comets has created a number of questions about the physical mechanism producing the radiation. There are now a variety of explanations for the emission, from thermal bremsstrahlung of electrons off neutrals or dust, to charge exchange induced emission from solar wind ions, to scattering of solar X-rays from attogram dust, to reconnection of solar magnetic field lines. In an effort to understand this new phenomenon, we observed but failed to detect in the X-ray the very dusty and active comet C/Hale-Bopp 1995 O1 over a two year period, September 1996 to December 1997, using the ROSAT HRI imaging photometer at 0.1-2.0 keV and the ASCA SIS imaging spectrometer at 0.5-10.0 keV. The results of our Hale-Bopp non-detections, when combined with spectroscopic imaging 0.08-1.0 keV observations of the comet by EUVE and BeppoSAX, show that the emission has the same spectral shape and strong variability seen in other comets. Comparison of the ROSAT photometry of the comet to our ROSAT database of 8 comets strongly suggests that the overall X-ray faintness of the comet was due to an emission mechanism coupled to gas, and not dust, in the comet's coma. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Rutherford Appleton Lab, Dept Space Sci, Didcot OX11 0QX, Oxon, England. RP Lisse, CM (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RI Lisse, Carey/B-7772-2016 OI Lisse, Carey/0000-0002-9548-1526 NR 20 TC 32 Z9 32 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PY 1999 VL 77 IS 3 BP 283 EP 291 DI 10.1023/A:1006274812124 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA 249RQ UT WOS:000083346400023 ER PT S AU Hinkal, S Jenstrom, D Florez, J Bremer, JC Hersh, M Neuberger, D Kindsfather, R AF Hinkal, S Jenstrom, D Florez, J Bremer, JC Hersh, M Neuberger, D Kindsfather, R BE Barnes, WL TI Advanced Geosynchronous Studies Imager: Instrument system design SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc DE geosynchronous; GOES; imager AB The Advanced Geosynchronous Studies Imager (AGSI) system design combines the latest available technologies into an instrument design concept which could deliver the improved performance sought by the National Weather Service at NOAA and meet NASA earth system science goals in a joint program. The instrument could cover the Earth disk every 15 minutes with subsatellite point resolution from 1/2 kilometer in the visible to 2 kilometers in the long wave infrared. Simultaneously, it could provide coverage of a 3000 x 5000 kilometer region in 5 minute intervals and 30 second updates of a 1000 kilometer square region containing a weather system of interest. We found that performance margins could be improved even as we drove the design iterations with emphasis on reducing the mass. Scan speed was chosen by maximizing performance while trading off the acceptable impact on the total system. The resulting 18-channel design could deliver vastly improved performance over the present GOES without great increases in mass or volume, while still paying close attention to control of development costs and impact on the host spacecraft. The design could be adapted to changed requirements or descoped to have lower data rates and fewer channels. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hinkal, S (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 3 TC 2 Z9 2 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 2 EP 10 DI 10.1117/12.363510 PG 9 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700001 ER PT S AU Le Moigne, J Carr, J Chu, D Esper, J AF Le Moigne, J Carr, J Chu, D Esper, J BE Barnes, WL TI Advanced Geosynchronous Studies Imager (AGSI): Image Navigation and Registration (INR) system SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc DE AGSI; INR system; navigation; automatic image registration; error budget; image processing AB Accurate and automatic Image Navigation and Registration (INR) of remotely sensed data will be an essential element of future NASA satellite observation systems. INR describes the process by which geographic locations of the image pixels are computed and successive images from the same sensor are aligned to each other over time. For sensors such as the Advanced Geosynchronous Studies Imager (AGSI), a number of distortions prevent successive images from being perfectly registered to each other or to a fixed coordinate system. Most distortions in such images are the combined effects of sensor operation, satellite orbit and attitude, and atmospheric and terrain effects. These distortions are usually corrected by two methods; systematic correction, which relies on image acquisition models taking into account satellite orbit and attitude, sensor characteristics, platform/sensor relationship, and terrain models, and precision correction, which is feature-based, starting from the results of the systematic correction (usually accurate within a few pixels), and refining the geolocation or relative registration to subpixel precision (precision correction). This paper describes the AGSI INR requirements and concepts, the image navigation model, a description of some potential precision correction methods utilizing edge and wavelet features, and a study of all the different error sources. The issues of swath-to-swath correlation and channel-to-channel coregistration are also described. C1 NASA, Goddard Space Flight Ctr, Appl Informat Sci Branch, Greenbelt, MD 20771 USA. RP Le Moigne, J (reprint author), NASA, Goddard Space Flight Ctr, Appl Informat Sci Branch, Greenbelt, MD 20771 USA. NR 19 TC 0 Z9 0 U1 1 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 23 EP 34 DI 10.1117/12.363533 PG 12 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700003 ER PT S AU Myers, J AF Myers, J BE Barnes, WL TI The MODIS and ASTER airborne simulators SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc DE Earth Observing System; MODIS; ASTER; airborne sensors AB The NASA has built two airborne sensors to simulate space-borne instruments to be flown on the EOS (Earth Observing System) AM-I Term satellite, scheduled for launch in 1999. The intent of these airborne systems is to provide initial, or "precursor" data sets to EOS investigators for algorithm development, as well as to conduct calibration and validation under-flights after the AM-1 platform has been launched. The MODIS Airborne Simulator (MAS,) and the MODIS/ASTER Simulator (MASTER,) were designed to support investigations by the Moderate Resolution Imaging Spectro-radiometer, and the Advanced Spaceborne Thermal Emission and Reflection Radiometer science teams, respectively. C1 NASA, Ames Res Ctr, SAIC, Moffett Field, CA 94035 USA. RP Myers, J (reprint author), NASA, Ames Res Ctr, SAIC, Moffett Field, CA 94035 USA. NR 1 TC 0 Z9 0 U1 0 U2 2 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 269 EP 273 DI 10.1117/12.363521 PG 5 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700028 ER PT S AU van den Bosch, JM Myers, JS Fitzgerald, MT AF van den Bosch, JM Myers, JS Fitzgerald, MT BE Barnes, WL TI Accuracy assessment of MODIS Airborne Simulator (MAS) 1996-1998 SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc DE MODIS Airborne Simulator; absolute radiometric calibration; accuracy assessment AB In an effort to provide accuracy assessment of the visible and shortwave infrared (SWIR) channels of MODIS Airborne Sensor (MAS), the results of three inflight calibration/validation experiments from 1996-1998 are presented. Both MAS and Airborne Visible InfraRed Imaging Spectrometer (AVIRIS) were flown together on NASA's ER-2 over two bright targets (San Diego 1996 and Lunar Lake 1997). Additionally MAS acquired another bright target, Ivanpah Playa, in 1998. AVIRIS data were spectrally and spatially convolved to MAS specifications for cross comparisons. Predicted at sensor radiances using MODTRAN 3.5 constrained with irt situ data are then compared to MAS and convolved AVIRIS radiances for absolute radiometric calibration. C1 NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. RP van den Bosch, JM (reprint author), NASA, Dryden Flight Res Ctr, MS D1623G,POB 273, Edwards, CA 93523 USA. NR 2 TC 0 Z9 0 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 274 EP 283 DI 10.1117/12.363556 PG 10 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700029 ER PT S AU Pedelty, JA Markham, BL Barker, JL Seiferth, JC AF Pedelty, JA Markham, BL Barker, JL Seiferth, JC BE Barnes, WL TI Pre-launch noise characterization of the Landsat-7 Enhanced Thematic Mapper Plus (ETM Plus) SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc DE Landsat-7; ETM; noise; radiometry AB A noise characterization of the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) instrument was performed as part of a near-real time performance assessment and health monitoring program. Performance data for the integrated Landsat-7 spacecraft and ETM+ were collected before, during, and after the spacecraft thermal vacuum testing program at the Lockheed Martin Missiles and Space (LMMS) facilities in Valley Forge, PA. The Landsat-7 spacecraft and ETM+ instrument were successfully launched on April 15, 1999. The spacecraft and ETM+ are now nearing the end of the on orbit engineering checkout phase, and Landsat-7 is expected to be declared operational on or about July 15, 1999. A preliminary post-launch noise characterization was performed and compared with the pre-launch characterization. In general the overall noise levels in the ETM+ are at or below the specification levels. Coherent noise is seen in most bands, but is only operationally significant when imaging in the panchromatic band (band 8). This coherent noise has an amplitude as high as similar to 3 DN (peak-to-peak, high gain) at the Nyquist rate of 104 kHz, and causes the noise levels in panchromatic band images at times to exceed the total noise specification by up to similar to 10%. However, this 104 kHz noise is now much weaker than it was prior to the successful repair of the ETM+ power supplies that was completed in May 1998. Weak and stable coherent noise at similar to 5 kHz is seen in all bands in the prime focal plane (bands 1-4 and 8) with the prime (side A) electronics. Very strong coherent noise at similar to 20 kHz is seen in a few detectors of bands 1 and 8, but this noise is almost entirely in the turn-around region between scans when the ETM+ is not imaging the Earth. Strong coherent noise was seen in 2 detectors of band 5 during some of the pre-launch testing; however, this noise seems to be temperature dependent, and has not been seen in the current on orbit environment. Strong 91 kHz coherent noise was observed in the redundant (side B) panchromatic band data after the completion of spacecraft thermal vacuum testing. The cause of this coherent noise was identified as a failed capacitor that was replaced prior to launch, and this noise was not seen in the final pre-launch test. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Pedelty, JA (reprint author), NASA, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. RI Markham, Brian/M-4842-2013 OI Markham, Brian/0000-0002-9612-8169 NR 4 TC 2 Z9 2 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 376 EP 387 DI 10.1117/12.363534 PG 12 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700040 ER PT S AU Montgomery, H Che, NZ Bowser, J AF Montgomery, H Che, NZ Bowser, J BE Barnes, WL TI SRCA radiometric calibration tracking from pre-launch to on-orbit SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc DE remote sensing; radiometric calibration AB The launch-related spectral band radiance change of the Spectro-Radiometric Calibration Assembly (SRCA) of MODurate Resolution Imaging Spectrometer (MODIS) is mainly attributable to its lamp temperature variations. Comparison of the spectral profiles, measured by the SRCA at different times, provides a way of tracking change in the band radiance while the integrated SRCA radiance remains constant. Prelaunch the SRCA was calibrated against a ground Spherical Integration Source(SIS(100). Meanwhile, the SRCA calibrations were run in spectral and radiometric modes. Comparison of the on-orbit data from the SRCA spectral and radiometric modes to prelaunch data will transfer SIS(100) ground calibration to orbit. For validation, data from TV at nominal temperature plateau will define the radiometric transfer; this transfer will be applied to SRCA data measured at other temperature plateaus and compared with the measured SIS(100) radiance values. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Montgomery, H (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 3 TC 2 Z9 2 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 388 EP 394 DI 10.1117/12.363535 PG 7 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700041 ER PT S AU Dabney, PW Kovalick, WM Bur, MJC Russell, CA Tierney, MR Irons, JR AF Dabney, PW Kovalick, WM Bur, MJC Russell, CA Tierney, MR Irons, JR BE Barnes, WL TI Inter-comparison of sensor calibration techniques for the advanced solid-state array spectroradiometer (ASAS) as a performance validation tool SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc DE radiometer; imaging; hyperspectral; airborne; calibration AB The Advanced Solid-state Array Spectroradiometer (ASAS), an airborne hyperspectral off-nadir pointable pushbroom imager, has participated in a variety of remote sensing field campaigns and has historically been calibrated using a radiative transfer technique. Recent campaigns have provided several candidate calibration target image sites that can and have been used to validate instrument radiometric performance. Limitations in the sensor's CCD sensitivity and integrating sphere source exitance provide a less than satisfactory calibration in the blue (less than 500nm) and near-IR (above 900nm) wavelength bands and a vicarious calibration of these bands is under consideration. This paper will compare "at sensor radiance" retrieved from a target of known spectral radiance using detector gains derived from laboratory calibration to radiances retrieved using detector gains derived from a well characterized ground calibration site. Physical reasons for the discrepancies and problems will be offered and discussed along with arguments for a combined vicarious and laboratory radiative transfer calibration. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Dabney, PW (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Irons, James/D-8535-2012; Dabney, Philip/C-9976-2013 NR 7 TC 0 Z9 0 U1 0 U2 3 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 442 EP 452 DI 10.1117/12.363540 PG 11 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700046 ER PT S AU Lee, RB Thomas, S Priestley, KJ Barkstrom, BR Paden, J Pandey, DK Smith, GL Al-hajjah, A Wilson, RS AF Lee, RB Thomas, S Priestley, KJ Barkstrom, BR Paden, J Pandey, DK Smith, GL Al-hajjah, A Wilson, RS BE Barnes, WL TI Analyses of on-orbit determinations of the Clouds and the Earth's Radiant Energy System (CERES) thermistor bolometer sensor zero-radiance offsets SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc DE calibrations; radiometry; climate; CERES; EOS; TRMM; ESE; Terra; radiance; bolometer ID RADIATION BUDGET EXPERIMENT; CALIBRATIONS; INSTRUMENT; FLIGHT; SCIENCE; TRMM AB The Clouds and Earth's Radiant Energy System (CERES) missions were designed to measure broadband earth-reflected shortwave solar (0.3 mu m to <5.0 mu m) and earth-emitted longwave (5.0 mu m to >100 mu m) radiances as well as earth-emitted narrow-band radiances in the water vapor window region between 8 mu m and 12 mu m. However, the CERES scanning thermistor bolometer sensor zero-radiance offsets were found to vary as much as 1.0 Wm(-2)sr(-1) with the scan angle measurement geometry due to gravitational forces and systematic electronic noise. To minimize the gravitational effects, the Tropical Rainfall Measuring Mission (TRMM) Spacecraft CERES sensors' offsets were derived on-orbit as functions of scan elevation and azimuth angles from the January 7-8, 1998 radiometric observations of deep cold space, representative of a 3 K blackbody. In this paper, the TRMM/CERES six orbit data base of on-orbit derived offsets is presented and analyzed to define the sampling requirements for the CERES sensors located on the Earth Science Enterprise (ESE) Terra Spacecraft and on the Earth Observing System (EOS) Afternoon (PM-I) Spacecraft, scheduled for launches in 1999 and 2000, respectively. Analyses of the TRMM/CERES shortwave sensor earth radiance measurements indicate that offsets can be determined on-orbit at the +/- 0.02 Wm(-2)sr(-1) precision level. Offset measuring techniques and sampling requirements are discussed for the TRMM and ESE missions. Ground, pre-launch Terra CERES cross-track scan offsets are presented and described which were measured as a function of scan angle. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Lee, RB (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. NR 19 TC 11 Z9 11 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 482 EP 493 PG 12 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700050 ER PT S AU Chapman, JJ Grant, MS Bockman, J Clark, VM Hess, PC AF Chapman, JJ Grant, MS Bockman, J Clark, VM Hess, PC BE Barnes, WL TI Assessment of selected CERES electronic component survivability under simulated overvoltage conditions SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc C1 NASA, LaRC, Hampton, VA 23665 USA. RP Chapman, JJ (reprint author), NASA, LaRC, Hampton, VA 23665 USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 494 EP 502 DI 10.1117/12.363546 PG 9 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700051 ER PT S AU Hollenhorst, R Chesters, D AF Hollenhorst, R Chesters, D BE Barnes, WL TI Advanced geosynchronous studies imager: Ground system architecture SO EARTH OBSERVING SYSTEMS IV SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Earth Observing Systems IV CY JUL 18-20, 1999 CL DENVER, CO SP SPIE, Remote Sensing Soc AB During 1997-98, the NASA-NOAA Advanced Geosynchronous Studies (AGS) program sponsored work to explore the possibility of designing a high-quality imaging radiometer for the future GOES platforms. The AGS Imager (AGSI) design calls for the acquisition of 12-bit digital images every few minutes in 18 spectral bands with horizontal resolutions ranging from 0.3 to 1.5 km on a full-earth disk (diameter 12,000 km). The resulting raw sensor data stream is approximately 300 Mbits/sec, uncompressed. The AGSI ground system must convert the sensor data into calibrated, earth-located "Level 1b" images and deliver them to NOAA and to the science community within minutes of reception. To accomplish this high-speed digital-image delivery, the AGSI downlink design calls for lossless compression to 150 Mbits/sec, packetized using CCSDS standards with error-correction, and broadcast in Ka-band to a low-precipitation site like White Sands, NM. There, the AGSI ground system performs the following sequence of operations: Analyze calibrations Perform ground-based attitude determination using Kalman filter and ground track image correlations Interpolate attitude to detector sample times Apply calibrations to each detector element sample Project detector element samples to fixed coordinate system Fit detector element samples to produce ground-based pixels Store ground-based pixel files Produce end-item products Deliver products to users Stage the data to near-on-line media Buffer an entire Earth scan swath Maintain history of images for limited period of time The presentation will describe a cost-effective, parallelized computer system to accomplish these tasks in real time. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hollenhorst, R (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3236-9 J9 P SOC PHOTO-OPT INS PY 1999 VL 3750 BP 526 EP 535 DI 10.1117/12.363549 PG 10 WC Engineering, Aerospace; Remote Sensing; Optics SC Engineering; Remote Sensing; Optics GA BN92F UT WOS:000083487700054 ER PT J AU Yano, H AF Yano, H TI Japanese contribution to in-situ meteoroid and debris measurement in the near Earth space SO EARTH PLANETS AND SPACE LA English DT Article ID COSMIC DUST AB This paper reviews major results of present studies and recent developments for future missions in the Japanese space program regarding in-situ measurement and collection of micrometeoroids and orbital debris in the near Earth space. Japan's contribution in this area began with the post flight impact analysis of the Space Flyer Unit (SFU) satellite which was returned to Earth in 1996 after 10-month exposure in space. Despite a decade later than similar efforts first conducted in the USA and Europe, it resulted in a record of over 700 hypervelocity impact signatures, which now forms the nation's first database of real space impacts being open to public in the Internet. Together with laboratory impact tests, both morphological and elemental analyses of the impact craters yielded new insights of the meteoroid to debris ratio as well as flux variation compared with the previous spacecraft. The next step was a passive aerogel exposure in the STS-85 shuttle mission in 1997. No hypervelocity impact was found there but its experience has been incorporated for designing a microparticle collector to be on-board the Japan Experiment Module-Exposed Facility of the International Space Station. All of such "passive" collection of micro-impact features, however, still leave the significant uncertainty in the quest of their origins. Therefore an aerogel-based "hybrid" dust collector and detector (HD-CAD) is currently under the development. It measures time of impact and deduces impactors' orbital and physical parameters by detecting impact flash while still capturing them intact. The system is suitable for both (1) sample return missions in LEO as well as to parent bodies of meteoroids, i.e., comets and asteroids, and (2) one-way mission to where the thermal and plasma environment is such that impact induced plasma detectors may suffer from significant noise, e.g., a Mercury orbiter and a solar probe. Together with unambiguous dust samples from a comet by STARDUST and an asteroid by MUSES-C as references, the HD-CAD in the LEO will be able to deduce the accretion rates of the cometary and asteroidal dust grains on the Earth. C1 NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. RP Yano, H (reprint author), Inst Space & Astronaut Sci, Planetary Sci Div, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2298510, Japan. NR 46 TC 3 Z9 3 U1 0 U2 2 PU TERRA SCIENTIFIC PUBL CO PI TOKYO PA 2003 SANSEI JIYUGAOKA HAIMU, 5-27-19 OKUSAWA, SETAGAYA-KU, TOKYO, 158, JAPAN SN 1343-8832 J9 EARTH PLANETS SPACE JI Earth Planets Space PY 1999 VL 51 IS 11 BP 1233 EP 1246 PG 14 WC Geosciences, Multidisciplinary SC Geology GA 272CH UT WOS:000084632600009 ER PT B AU Polovina, JJ Haight, WR AF Polovina, JJ Haight, WR GP UNIV. OF ALASKA SEA GRANT COLLEGE PROGRAM UNIV. OF ALASKA SEA GRANT COLLEGE PROGRAM UNIV. OF ALASKA SEA GRANT COLLEGE PROGRAM TI Climate variation, ecosystem dynamics, and fisheries management in the Northwestern Hawaiian Islands SO ECOSYSTEM APPROACHES FOR FISHERIES MANAGEMENT SE LOWELL WAKEFIELD FISHERIES SYMPOSIA SERIES LA English DT Proceedings Paper CT Symposium on Ecosystem Considerations in Fisheries Management CY SEP 30-OCT 03, 1998 CL ANCHORAGE, AK SP Alaska Sea Grant Coll Program, Alaska Dept Fish & Game Commercial Fisheries Div, Alaska Dept Fish & Game, Div Sport Fish, N Pacific Fishery Management Council, US Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Amer Fisheries Soc, Alaska Chapter, Amer Fisheries Soc, Colorado Wyoming Chapter, Amer Fisheries Soc, N Pacific Int Chapter, Amer Fisheries Soc, Western Div AB A dramatic ecosystem shift from high to low carrying capacity occurred in the late 1980s in the northern portion of the Hawaiian Archipelago. This shift was observed for a range of trophic levels and species including seabirds, monk seals, spiny lobsters, and reef fishes. Concurrent with the ecosystem shift were physical changes associated with weakening of the Aleutian Low Pressure System and the Subtropical Counter Current. A trap fishery operating at Maro Reef rapidly depleted the spiny lobster population after the ecosystem shift. At an adjacent bank, Laysan Island, closed to commercial lobster fishing, the spiny lobster population declined much more gradually but ultimately was depleted as well. Harvest from the lobster fishery during much of the 1990s averaged about 25% of the harvest in the 1980s. Fishermen adjusted to the reduced harvest by moving into the pelagic longline fishery which was apparently not impacted by the ecosystem shift. C1 Natl Marine Fisheries Serv, SW Fisheries Ctr, Honolulu Lab, Honolulu, HI 96822 USA. RP Polovina, JJ (reprint author), Natl Marine Fisheries Serv, SW Fisheries Ctr, Honolulu Lab, 2570 Dole St, Honolulu, HI 96822 USA. NR 10 TC 5 Z9 5 U1 0 U2 2 PU UNIV ALASKA SEA GRANT PI FAIRBANKS PA POB 755040, 205 ONEILL BLDG, FAIRBANKS, AK 99775 USA BN 1-56612-061-6 J9 LOW WAKE FI PY 1999 VL 16 BP 23 EP 32 PG 10 WC Fisheries SC Fisheries GA BP34Q UT WOS:000084758600002 ER PT B AU Pennoyer, S Rue, F Williams, D AF Pennoyer, S Rue, F Williams, D GP UNIV. OF ALASKA SEA GRANT COLLEGE PROGRAM UNIV. OF ALASKA SEA GRANT COLLEGE PROGRAM UNIV. OF ALASKA SEA GRANT COLLEGE PROGRAM TI Bering Sea ecosystem - A call to action: An interagency collaborative white paper SO ECOSYSTEM APPROACHES FOR FISHERIES MANAGEMENT SE LOWELL WAKEFIELD FISHERIES SYMPOSIA SERIES LA English DT Proceedings Paper CT Symposium on Ecosystem Considerations in Fisheries Management CY SEP 30-OCT 03, 1998 CL ANCHORAGE, AK SP Alaska Sea Grant Coll Program, Alaska Dept Fish & Game Commercial Fisheries Div, Alaska Dept Fish & Game, Div Sport Fish, N Pacific Fishery Management Council, US Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Amer Fisheries Soc, Alaska Chapter, Amer Fisheries Soc, Colorado Wyoming Chapter, Amer Fisheries Soc, N Pacific Int Chapter, Amer Fisheries Soc, Western Div AB The Bering Sea is one of the most productive large marine ecosystems in the world, This vast area, almost 2.6 million square kilometers, is located prominently between Alaska and Russia and supports more than 450 species of fish, crustaceans, and mollusks; 50 species of seabirds; and 25 species of marine mammals. The breeding seabird population of 25 million represents 43% of breeding seabirds in the United States. It provides a world class fishery; the pristine waters contribute 56% of the U.S. fishery production. The total landed value of the catch was one billion dollars in 1997. In recent years the Bering Sea ecosystem has been showing signs of stress. Both marine mammals and seabirds are experiencing population declines. Scientists' knowledge of the various relationships in the ecosystem is limited. Managers need vital and complex information to properly carry out their responsibilities in future years. The ecosystem demands a long-term commitment to assure its protection. It is an extremely valuable treasure of the United States. A showcase ecosystem of the United States and the world, its long-term protection will require comprehensive and coordinated research. C1 Natl Marine Fisheries Serv, Juneau, AK 99801 USA. RP Pennoyer, S (reprint author), Natl Marine Fisheries Serv, Juneau, AK 99801 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV ALASKA SEA GRANT PI FAIRBANKS PA POB 755040, 205 ONEILL BLDG, FAIRBANKS, AK 99775 USA BN 1-56612-061-6 J9 LOW WAKE FI PY 1999 VL 16 BP 705 EP 715 PG 11 WC Fisheries SC Fisheries GA BP34Q UT WOS:000084758600049 ER PT J AU Potter, CS Klooster, S Brooks, V AF Potter, CS Klooster, S Brooks, V TI Interannual variability in terrestrial net primary production: Exploration of trends and controls on regional to global scales SO ECOSYSTEMS LA English DT Article DE net primary production; remote sensing; Normalized Difference Vegetation Index (NDVI); interannual variation ID NDVI DATA SET; CLIMATE VARIABILITY; CARBON-DIOXIDE; BOREAL FOREST; MODEL; ECOSYSTEMS; SATELLITE; EXCHANGE; DYNAMICS; TUNDRA AB Climate and biophysical regulation of terrestrial plant production and interannual responses to anomalous events were investigated using the NASA Ames model version of CASA (Carnegie-Ames-Stanford Approach) in a transient simulation mode. This ecosystem model has been calibrated for simulations driven by satellite vegetation index data from the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) over the mid-1980s. Relatively large net source fluxes of carbon were estimated from terrestrial vegetation about 6 months to 1 year following El Nino events of 1983 and 1987, whereas the years 1984 and 1988 showed a drop in net primary production (NPP) of 1-2 Pg (10(15) g) C from their respective previous years. Zonal discrimination of model results implies that the northern hemisphere low latitudes could account for almost the entire 2 Pg C decrease in global terrestrial NPP predicted from 1983 to 1984. Model estimates further suggest that from 1985 to 1988, the northern middle-latitude zone (between 30 degrees and 60 degrees N) was the principal region driving progressive increases in NPP, mainly by an expanded growing season moving toward the zonal latitude extremes. Comparative regional analysis of model controls on NPP reveals that although Normalized Difference Vegetation Index "greenness" can alone account for 30%-90% of the variation in NPP interannual anomalies, temperature or radiation loading can have a fairly significant I-year lag effect on annual NPP at middle- to high-latitude zones, whereas rainfall amount and temperature drying effects may carry over with at least a 2-year lag time to influence NPP in semiarid tropical zones. C1 NASA, Ecosyst Sci Branch, Ames Res Ctr, Moffett Field, CA 94035 USA. Calif State Univ Monterey Bay, Seaside, CA 93955 USA. NASA, Johnson Controls World Serv, Ames Operat, Moffett Field, CA 94035 USA. RP Potter, CS (reprint author), NASA, Ecosyst Sci Branch, Ames Res Ctr, Mail Stop 242-3, Moffett Field, CA 94035 USA. NR 38 TC 110 Z9 114 U1 3 U2 41 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1432-9840 J9 ECOSYSTEMS JI Ecosystems PD JAN-FEB PY 1999 VL 2 IS 1 BP 36 EP 48 DI 10.1007/s100219900056 PG 13 WC Ecology SC Environmental Sciences & Ecology GA 171HT UT WOS:000078858100004 ER PT S AU Hartley, FT Malek, CK AF Hartley, FT Malek, CK BE Payne, F Parameswaran, AM TI Nanometer X-ray lithography SO EDUCATION IN MICROELECTRONICS AND MEMS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Education in Microelectronics and MEMS CY OCT 28-29, 1999 CL QUEENSLAND, AUSTRALIA SP SPIE, IREE Soc, Queensland Govt State Dev, Griffith Univ Microelectr Engn Soc, Australia, IEEE, Electron Devices Soc, Electrochem Soc DE X-rays; lithography on non-planar surfaces; conformal coating; large depth-of-field; nanolithography ID PHOTORESIST AB New developments for X-ray nanomachining include pattern transfer onto non-planar surfaces coated with electrodeposited resists using synchrotron radiation X-rays through extremely high-resolution masks made by chemically assisted focused ion beam lithography. Standard Ultraviolet (UV) photolithographic processes cannot maintain sub-micron definitions over large variation in feature topography. The ability of X-ray printing to pattern thin or thick layers of photoresist with high resolution on non-planar surfaces of large and complex topographies with limited diffraction and scattering effects and no substrate reflection is known and can be exploited for patterning microsystems with non-planar 3-D geometries as well as multisided and multilayered substrates. Thin conformal coatings of electro-deposited positive and negative tone photoresists have been shown to be X-ray sensitive and accommodate sub-micron pattern transfer over surfaces of extreme topographical variations (over 100 microns). Chemically assisted focused ion beam selective anisotropic erosion was used to fabricate X-ray masks directly. Masks with feature sizes less than 20 nm through 7 microns of gold (aspect ratio similar to 350) were made on bulk silicon substrates and X-ray mask membranes. The technique is also applicable to other high density materials. Such masks enable the primary and secondary patterning and/or 3D machining of Nano-Electro-Mechanical Systems (NEMS)s over large depths or complex relief and the patterning of large surface areas with sub-optically dimensioned features. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hartley, FT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 24 TC 2 Z9 2 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3495-7 J9 P SOC PHOTO-OPT INS PY 1999 VL 3894 BP 44 EP 54 PG 3 WC Education, Scientific Disciplines; Optics SC Education & Educational Research; Optics GA BP26N UT WOS:000084510000005 ER PT J AU McGregor, JW Baroth, EC AF McGregor, JW Baroth, EC TI Ethernet data acquisition - An independent evaluation SO EE-EVALUATION ENGINEERING LA English DT Article C1 Software Res, Lancaster, CA 93535 USA. RP McGregor, JW (reprint author), CALTECH, Jet Prop Lab, Measurement Technol Ctr, Measurement Syst Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU NELSON PUBLISHING PI NOKOMIS PA 2504 NORTH TAMIAMI TRAIL, NOKOMIS, FL 34275-3482 USA SN 0149-0370 J9 EE-EVAL ENG JI EE-Eval. Eng. PD JAN PY 1999 VL 38 IS 1 BP 22 EP + PG 5 WC Engineering, Electrical & Electronic SC Engineering GA 160DL UT WOS:000078215100003 ER PT B AU Gompf, R Holdstock, P Chubb, J AF Gompf, R Holdstock, P Chubb, J GP ESD ESD TI Electrostatic test methods compared SO ELECTRICAL OVERSTRESS/ELECTROSTATIC DISCHARGE SYMPOSIUM PROCEEDINGS, 1999 LA English DT Proceedings Paper CT 1999 EOS/ESD Symposium CY SEP 28-30, 1999 CL ORLANDO, FL SP ESD Assoc, IEEE, Electron Devices Soc AB The purpose of this paper is to demonstrate that electrostatic materials can be evaluated and ranked from highest to lowest in triboelectric generating capacity, that the ranking is a function of the material, and this ranking is not a function of the rubbing material. Three researches participated in this study and all were chosen by Paul Holdstock who first suggested this study be undertaken. Each researcher used the method he was most familiar with. The test methods used were: (1) The NASA Triboelectric tester, (2) The modified Shirley Method 18 Test and, (3) The JCI ad-hoc tribocharging test In addition to the three tribocharging tests, corona charging tests were also done. Triboelectric testing has been a scientific challenge dating back to 1600 when the "amber effect" was recorded by William Gilbert in a treatise entitled "De Magnete." Volumes have been written on this subject since that time. Nearly every one of the 20 volumes of the EOS/ESD Proceedings has had at least one research paper on this type of testing. In the 1984 EOS/ESD Symposium Proceedings (Gompf, p58) and 1986 EOS/ESD Symposium Proceedings (Gompf, p151) this author discussed two triboelectric devices used at the Kennedy Space Center for the testing of materials. Triboelectric articles continue to be of importance to the scientific community and appear regularly at the annual EOS/ESD Symposium. In the 1998 Proceedings, Boone said, "Triboelectric test results were weighted more heavily than any of the others, since it was felt that this was the most important performance characteristic of the fabric tested" (Boone, p16). At this time this author knows of no other way to measure both the generating and dissipating capacity of a material except by triboelectric testing (Gompf, MTB 402-85, p4). However, there are questions concerning this technique that need good scientific answers. This paper addresses one of the more important questions. In evaluation of the generating potential of a material, does the second rubbing material have an influence in the "ranking" of generating potential? While it is true that the selected rubbing material does influence the amount of charge generated, this paper suggests that it does not alter the relative position of generating capacity. C1 NASA, Mat Sci Lab, Kennedy Space Ctr, FL 32899 USA. RP Gompf, R (reprint author), NASA, Mat Sci Lab, Kennedy Space Ctr, FL 32899 USA. NR 10 TC 2 Z9 2 U1 0 U2 0 PU ESD ASSOCIATION PI ROME PA 7900 TURIN RD, BLDG 3, SUITE 2, ROME, NY 13440-2069 USA BN 1-58537-007-X PY 1999 BP 49 EP 53 DI 10.1109/EOSESD.1999.818989 PG 5 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BP21E UT WOS:000084417700007 ER PT S AU Hartley, FT Malek, CK AF Hartley, FT Malek, CK BE Bergmann, NW Reinhold, O Tien, NC TI Nanometer X-ray lithography SO ELECTRONICS AND STRUCTURES FOR MEMS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT SPIE Conference on Electronics and Structures for MEMS CY OCT 27-29, 1999 CL QUEENSLAND, AUSTRALIA SP SPIE, IREE Soc, Queensland Govt State Dev, IEEE, Electron Devices Soc, Electrochem Soc, Griffith Univ Microelectr Engn Soc, Australia DE X-rays; lithography on non-planar surfaces; conformal coating; large depth-of-field; nanolithography ID PHOTORESIST AB New developments for X-ray nanomachining include pattern transfer onto non-planar surfaces coated with electrodeposited resists using synchrotron radiation X-rays through extremely high-resolution masks made by chemically assisted focused ion beam lithography. Standard Ultraviolet (UV) photolithographic processes cannot maintain sub-micron definitions over large variation in feature topography. The ability of X-ray printing to pattern thin or thick layers of photoresist with high resolution on non-planar surfaces of large and complex topographies with limited diffraction and scattering effects and no substrate reflection is known and can be exploited for patterning microsystems with non-planar 3-D geometries as well as multisided and multilayered substrates. Thin conformal coatings of electro-deposited positive and negative tone photoresists have been shown to be X-ray sensitive and accommodate sub-micron pattern transfer over surfaces of extreme topographical variations (over 100 microns). Chemically assisted focused ion beam selective anisotropic erosion was used to fabricate Xray masks directly. Masks with feature sizes less than 20 nm through 7 microns of gold (aspect ratio similar to 350) were made on bulk silicon substrates and X-ray mask membranes. The technique is also applicable to other high density materials. Such masks enable the primary and secondary patterning and/or 3D machining of Nano-Electro -Mechanical Systems (NEMS)s over large depths or complex relief and the patterning of large surface areas with sub-optically dimensioned features. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hartley, FT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 24 TC 3 Z9 3 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3492-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3891 BP 69 EP 79 PG 11 WC Engineering, Electrical & Electronic; Engineering, Mechanical; Optics SC Engineering; Optics GA BP26K UT WOS:000084509700008 ER PT S AU Hartley, FT AF Hartley, FT BE Bergmann, NW Reinhold, O Tien, NC TI Micropump technology and applications SO ELECTRONICS AND STRUCTURES FOR MEMS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT SPIE Conference on Electronics and Structures for MEMS CY OCT 27-29, 1999 CL QUEENSLAND, AUSTRALIA SP SPIE, IREE Soc, Queensland Govt State Dev, IEEE, Electron Devices Soc, Electrochem Soc, Griffith Univ Microelectr Engn Soc, Australia DE peristaltics; micropump; valves; flow metering; eutectic bonding; thrusters; fluidic reaction wheel; heat exchanger; Joule-Thompson cooler; spectrometer AB This paper describes reversed engineered biological peristaltics through the insightful evolution of MEMS technology. While the emphasis on pump applications is in the miniaturization of spacecraft bus and payload, terrestrial applications are evident. For spacecraft propulsion, the use of the peristaltic pump as a low leakage valve, a pressure regulator and a flow meter are discussed. Spacecraft stabilization is addressed through a fluidic reaction wheel while thermal management of spacecraft, flight instruments and lander is addressed through heat pumps and Joule-Thompson compressors. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hartley, FT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 2 Z9 2 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3492-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3891 BP 403 EP 409 DI 10.1117/12.364470 PG 7 WC Engineering, Electrical & Electronic; Engineering, Mechanical; Optics SC Engineering; Optics GA BP26K UT WOS:000084509700045 ER PT S AU Hartley, FT AF Hartley, FT BE Bergmann, NW Reinhold, O Tien, NC TI Development and terrestrial applications of a nano-g accelerometer SO ELECTRONICS AND STRUCTURES FOR MEMS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT SPIE Conference on Electronics and Structures for MEMS CY OCT 27-29, 1999 CL QUEENSLAND, AUSTRALIA SP SPIE, IREE Soc, Queensland Govt State Dev, IEEE, Electron Devices Soc, Electrochem Soc, Griffith Univ Microelectr Engn Soc, Australia DE nano-gravity accelerometer; seismometers; gradiometers; anemometers; spectrometers; bulk micromachining; eutectic bonding; electrostatic caging; hermetic seal AB The ultra-sensitive accelerometer, developed for NASA to monitor the microgravity environments of Space Shuttle, free orbiters and Space Station, needed to measure accelerations up to 10 mg with an absolute accuracy of 10 nano-g(10(-8)g) for at least two orbits (10(4) seconds) to resolve accelerations associated with orbital drag. Also, the accelerometers needed to have less than 10(-9) F.S. off-axis sensitivity; to be thermally and magnetically inert; to be immune to quiescent shock, and to have an in-situ calibration capability. The utilization of these accelerometers in multi-axis compact seismometers designs that have twelve decades of dynamic range, density profilometers, precision gradiometers, gyros and vibration isolation designs and applications will be discussed. Finally, examples of the versatility of the proof mass suspension system will be demonstrated through the transformation of the basic accelerometer into sensitive anemometers and imaging spectrometers. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hartley, FT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 1 Z9 1 U1 1 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3492-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3891 BP 410 EP 415 DI 10.1117/12.364471 PG 6 WC Engineering, Electrical & Electronic; Engineering, Mechanical; Optics SC Engineering; Optics GA BP26K UT WOS:000084509700046 ER PT S AU Buehler, M Cheng, LJ Orient, O Thelen, M Gompf, R Bayliss, J Rauwerdink, J AF Buehler, M Cheng, LJ Orient, O Thelen, M Gompf, R Bayliss, J Rauwerdink, J BE Taylor, DM TI MECA electrometer: Initial calibration experiments SO ELECTROSTATICS 1999 SE INSTITUTE OF PHYSICS CONFERENCE SERIES LA English DT Article; Proceedings Paper CT 10th Internatioal Conference on Electrostatics CY MAR 28-31, 1999 CL CAMBRIDGE, ENGLAND AB The Mars '01 lander contains an electrometer designed to evaluate the electrostatic nature of the Martian regolith (soil) and atmosphere. In this paper the initial calibration and response of the triboelectric sensors were measured between -60 degrees C and room temperature. The sensor has an electric field sensitivity of 35 kV/cm.V and room temperature drift of similar to 3 mu V/sec. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NASA, Kennedy Space Flight Ctr, Washington, DC 20546 USA. RP Buehler, M (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NR 2 TC 7 Z9 7 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0951-3248 BN 0-7503-0638-6 J9 INST PHYS CONF SER PY 1999 VL 163 BP 189 EP 196 PG 8 WC Engineering, Electrical & Electronic; Instruments & Instrumentation; Physics, Applied; Physics, Multidisciplinary SC Engineering; Instruments & Instrumentation; Physics GA BP11S UT WOS:000084179300036 ER PT B AU Nesbitt, JA Lei, JF AF Nesbitt, JA Lei, JF BE Hampikian, JM Dahotre, NB TI Diffusion barriers to increase the oxidative life of overlay coatings SO ELEVATED TEMPERATURE COATINGS: SCIENCE AND TECHNOLOGY III LA English DT Proceedings Paper CT Symposium on Elevated Temperature Coatings - Science and Technology III, at the 1999 TMS Annual Meeting CY FEB 28-MAR 04, 1999 CL SAN DIEGO, CA SP Minerals Met & Mat Soc, Mat Proc & Mfg Div, Surf Modificat & Coatings Technol Comm, Joint TMS/ASM, Struct Mat Div, Corros & Environm Effects Comm ID CYCLIC OXIDATION; ALLOYS; INTERDIFFUSION AB Currently, most blades and vanes in the hottest section of aero gas turbine engines require some type of coating for oxidation protection. Newly developed single crystal superalloys have the mechanical potential to operate at increasingly higher component temperatures. However, at these elevated temperatures, coating/substrate interdiffusion can shorten the protective life of the coating. Diffusion barriers between overlay coatings and substrates are being examined to extend the protective life of the coating. A previously-developed finite-difference diffusion model has been modified to predict the oxidative life enhancement due to use of a diffusion barrier. The original diffusion model, designated COSIM, simulates Al diffusion in the coating to the growing oxide scale as well as Al diffusion into the substrate. The COSIM model incorporates an oxide growth and spalling model to provide the rate of Al consumption during cyclic oxidation. Coating failure is predicted when the Al concentration at the coating surface drops to a defined critical level. The modified COSIM model predicts the oxidative life of an overlay coating when a diffusion barrier is present eliminating diffusion of Al from the coating into the substrate. Both the original and the modified diffusion models have been used to predict the effectiveness of a diffusion barrier in extending the protective life of a NiCrAl overlay coating undergoing cyclic oxidation at 1100 degrees C. Experimentally, thin alumina films were deposited by evaporation and by RF magnetron sputtering on a Ni-base superalloy substrate. The effectiveness of the films in limiting interdiffusion was evaluated by forming diffusion couples with Ni by hot pressing and annealing at 1200 degrees C for 100 hrs. The evaporated alumina films have been shown to be an excellent diffusion barrier at this elevated temperature. However, it was found that the presence of the sputtered films decreased interdiffusion but allowed limited transport of Al and Cr across the film. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Nesbitt, JA (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 19 TC 1 Z9 1 U1 0 U2 3 PU MINERALS, METALS & MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086-7514 USA BN 0-87339-421-6 PY 1999 BP 131 EP 142 PG 12 WC Metallurgy & Metallurgical Engineering; Materials Science, Coatings & Films SC Metallurgy & Metallurgical Engineering; Materials Science GA BM93K UT WOS:000080184400012 ER PT B AU Newman, JC AF Newman, JC BE Beynon, JH Brown, MW Smith, RA Lindley, TC Tomkins, B TI Prediction of crack growth under variable-amplitude loading in thin-sheet 2024-T3 aluminum alloys SO ENGINEERING AGAINST FATIGUE LA English DT Proceedings Paper CT International Conference on the Importance of Understanding the Fundamentals of the Fatigue Process in Counteracting Its Effects in Engineering Components and Structures CY MAR 17-21, 1997 CL SHEFFIELD, ENGLAND ID CLOSURE-MODEL AB The present paper is concerned with the application of a 'plasticity-induced' crack closure model to study fatigue crack growth under various load histories. The model was based on the Dugdale model but modified to leave plastically deformed material in the wake of the advancing crack. The model was used to correlate crack growth rates under constant-amplitude loading and then to predict crack growth under variable-amplitude and spectrum loading on thin-sheet 2024-T3 aluminum alloys. Predicted crack-opening stresses agreed well with test data from the literature. The crack-growth lives agreed within a factor of two for single and repeated spike overloads/underloads and within 20% for spectrum loading. Differences were attributed to fretting-product-debris-induced closure and three-dimensional affects not included in the model. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Newman, JC (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 21 TC 6 Z9 6 U1 0 U2 0 PU A A BALKEMA PUBLISHERS PI LEIDEN PA SCHIPHOLWEG 107C, PO BOX 447, 2316 XC LEIDEN, NETHERLANDS BN 90-5410-969-6 PY 1999 BP 261 EP 268 PG 8 WC Engineering, Mechanical; Materials Science, Multidisciplinary; Mechanics SC Engineering; Materials Science; Mechanics GA BM94J UT WOS:000080198400027 ER PT S AU Freed, MA Shafto, MG Remington, RW AF Freed, MA Shafto, MG Remington, RW BE Chatty, S Dewan, P TI Employing simulation to evaluate designs: The APEX approach SO ENGINEERING FOR HUMAN-COMPUTER INTERACTION SE INTERNATIONAL FEDERATION FOR INFORMATION PROCESSING LA English DT Proceedings Paper CT 7th Working Conference on Engineering for Human-Computer Interaction CY SEP 14-18, 1998 CL IRAKLION, GREECE SP Int Federat Informat Processing, TC2, TC13 WG2 7, WG13 4 DE human performance modeling; human error; simulation; usability; design ID SOFTWARE; FIELD AB Computer simulation could be used to reduce the cost of designing human-machine systems, just as it is currently used in the design process for inanimate systems such as electronic circuits. However, past efforts have met with limited success due to difficulties modeling the human components of these systems. We have constructed a software framework and methodology for modeling human performance, APEX, that addresses several of these difficulties. This paper describes a methodology for using APEX to evaluate designs in complex, dynamic task environments; we then illustrate this process using an example from the domain of air traffic control. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Freed, MA (reprint author), NASA, Ames Res Ctr, Mail Stop 262-4, Moffett Field, CA 94035 USA. NR 23 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBLISHERS PI NORWELL PA 101 PHILIP DRIVE, ASSINIPPI PARK, NORWELL, MA 02061 USA SN 1571-5736 BN 0-412-83520-7 J9 INT FED INFO PROC PY 1999 VL 22 BP 207 EP 223 PG 17 WC Computer Science, Cybernetics; Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA BP38J UT WOS:000084929300012 ER PT S AU Delgado, F Abernathy, M White, J Lowrey, B AF Delgado, F Abernathy, M White, J Lowrey, B BE Verly, JG TI Real-time 3-D flight guidance with terrain for the X-38 SO ENHANCED AND SYNTHETIC VISION 1999 SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Enhanced and Synthetic Vision 1999 CY APR 05-06, 1999 CL ORLANDO, FL SP SPIE DE synthetic vision; simulation; flight visualization; flight guidance; human factors AB The NASA Johnson Space Center is developing a series of prototype flight test vehicles leading to a functional Crew Return Vehicle (CRV). The development of these prototype vehicles, designated as the X-38 program, will demonstrate which technologies are needed to build an inexpensive, safe, and reliable spacecraft that can rapidly return astronauts from onboard the International Space Station (ISS) to earth. These vehicles are being built using an incremental approach acid where appropriate, are taking advantage of advanced technologies that may help improve safety, decrease development costs, reduce development time, as well as outperform traditional technologies. This paper discusses the creation of real-time 3-D displays for flight guidance and situation awareness for the X-38 program. These displays feature the incorporation of real-time GPS position data, three-dimensional terrain models, heads-up display (HUD), and landing zone designations. The X-38 crew return vehicle is unique in several ways including that it does not afford the pilot a forward view through a wind screen, and utilizes a parafoil in the final flight phase. As a result, on-board displays to enhance situation awareness face challenges. While real-time flight visualization systems limited to running on high-end workstations have been created, only flight-rated Windows are available as platforms for the X-38 3-D displays. The system has been developed to meet this constraint, as well as those of cost, ease-of-use, reliability and extensibility. Because the X-38 is unpowered, and might be required to enter its landing phase from anywhere on orbit, the display must show, in real-time, acid in 3 dimensions, the terrain, ideal and actual glide path, recommended landing areas, as well as typical heads-up information. Maps, such as aeronautical charts, and satellite imagery are optionally overlaid on the 3-D terrain model to provide additional situation awareness. We will present a component-based toolkit for building these displays for use with the Windows operating systems. C1 NASA, Intelligent Syst Branch, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Delgado, F (reprint author), NASA, Intelligent Syst Branch, Lyndon B Johnson Space Ctr, ER2, Houston, TX 77058 USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3165-6 J9 P SOC PHOTO-OPT INS PY 1999 VL 3691 BP 149 EP 156 DI 10.1117/12.354416 PG 8 WC Automation & Control Systems; Engineering, Aerospace; Engineering, Civil SC Automation & Control Systems; Engineering GA BN68R UT WOS:000082586300015 ER PT J AU Short, JW Kvenvolden, KA Carlson, PR Hostettler, FD Rosenbauer, RJ Wright, BA AF Short, JW Kvenvolden, KA Carlson, PR Hostettler, FD Rosenbauer, RJ Wright, BA TI Natural hydrocarbon background in benthic sediments of Prince William Sound, Alaska: Oil vs coal SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID EXXON-VALDEZ-OIL; SUBTIDAL SEDIMENTS; SPILL; RESIDUES; TISSUES AB The source of the background hydrocarbons in benthic sediments of Prince William Sound (PWS), AK, where the 1989 Exxon Valdez oil spill (EVOS) occurred, has been ascribed to oil seeps in coastal areas of the Gulf of Alaska (GOA). We present evidence that coal is a more plausible source, including (i) high concentrations of total PAH (TPAH), between 1670 and 3070 ng/g, in continental shelf sediments adjacent to the coastal region containing extensive coal deposits; (ii) PAH composition patterns of sediments along with predictive models that are consistent with coal but not oil; (iii) low ratios (<0.2) of triaromatic steranes to methylchrysenes found in sediments and coals, contrasting with the high ratios (11 and 13) found in seep oil; and (iv) bioaccumulation of PAH in salmon collected within 100 m of the Katalla oil seeps but not in filter-feeding mussels collected near oilfield drainages 9 km from the seeps, indicating negligible transport of bioavailable PAH from Katalla seeps to the GOA. In contrast with oil, PAH in coal are not bioavailable, so the presence of coal in these benthic sediments confers no adaptive benefit to biota of the marine ecosystem with respect to PAH insults from anthropogenic sources. C1 Natl Marine Fisheries Serv, Auke Bay Lab, Alaska Fisheries Sci Ctr, NOAA, Juneau, AK 99801 USA. US Geol Survey, Menlo Park, CA 94025 USA. RP Short, JW (reprint author), Natl Marine Fisheries Serv, Auke Bay Lab, Alaska Fisheries Sci Ctr, NOAA, 11305 Glacier Highway, Juneau, AK 99801 USA. EM Jeff.Short@noaa.gov NR 28 TC 64 Z9 64 U1 1 U2 9 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD JAN 1 PY 1999 VL 33 IS 1 BP 34 EP 42 DI 10.1021/es980130w PG 9 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA 155NW UT WOS:000077954100024 ER PT S AU Wellman, J George, T Leon, R Fafard, S Zou, J Cockayne, DJH AF Wellman, J George, T Leon, R Fafard, S Zou, J Cockayne, DJH BE Barabasi, AL Krishnamurthy, M Liu, F Pearsall, T TI Transmission electron microscopy study of InGaAs/GaAs structural evolution near the Stranski-Krastanow transformation SO EPITAXIAL GROWTH-PRINCIPLES AND APPLICATIONS SE MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS LA English DT Proceedings Paper CT Symposium on Epitaxial Growth-Principles and Applications CY APR 05-08, 1999 CL SAN FRANCISCO, CA SP Mat Res Soc ID QUANTUM DOTS; INXGA1-XAS/GAAS AB An experimental study of the microstructure during formation and evolution of MOCVD-grown In0.6Ga0.4As/GaAs quantum dots (QDs) was undertaken to provide a more thorough understanding of the underlying growth principles. Transmission Electron Microscopy (TEM) was used to examine the evolution of the In0.6Ga0.4As/GaAs system in order to correlate photoluminescence (PL) spectra with structural data. In particular, we have examined the QD size evolution, capped and uncapped, and its possible contribution to the slight QD PL blueshift observed before QD saturation. TEM studies in the QD coalescence regime clarify the microstructural origins of the sharp decrease in QD PL due to large, incoherent islands observed in AFM and TEM images. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wellman, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Zou, Jin/B-3183-2009 OI Zou, Jin/0000-0001-9435-8043 NR 6 TC 0 Z9 0 U1 0 U2 0 PU MATERIALS RESEARCH SOCIETY PI WARRENDALE PA 506 KEYSTONE DRIVE, WARRENDALE, PA 15088-7563 USA SN 0272-9172 BN 1-55899-477-7 J9 MATER RES SOC SYMP P PY 1999 VL 570 BP 175 EP 180 PG 6 WC Materials Science, Multidisciplinary; Physics, Condensed Matter SC Materials Science; Physics GA BN69F UT WOS:000082591100024 ER PT B AU Corcoran, MF Swank, JH Petre, R Ishibashi, K Davidson, K Damineli, A Viotti, R Schmitt, JHMM AF Corcoran, MF Swank, JH Petre, R Ishibashi, K Davidson, K Damineli, A Viotti, R Schmitt, JHMM BE Morse, JA Humphreys, RM Damineli, A TI Resolving X-ray spectral variations in eta Carinae SO ETA CARINAE AT THE MILLENNIUM SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on ETA Carinae at the Millennium CY JUL 19-23, 1998 CL GALLATIN GATEWAY, MT ID SOURCE CATALOG; EMISSION; NEBULA AB We discuss the characteristics of the spatially-resolved X-ray spectrum of eta Carinae using data from EINSTEIN, ROSAT, and ASCA, paying particular attention to spatial and temporal variations. We review the temporal variability of the hard central source discovered by ROSAT (Corcoran et al. 1995) and, using newer data from ASCA show that the subsequent variation in the X-ray spectrum is either confined to a change in the emission measure of the source, or represents a surprising variation in the temperature distribution of the hot gas. We compare our results to expectations based on simple colliding wind binary models and show that while the observed spectral variations are consistent with the binary model, the variation in the intrinsic X-ray luminosity requires a substantial change in the temperature distribution of the hot plasma if the colliding wind model is correct. C1 NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. RP Corcoran, MF (reprint author), NASA, Goddard Space Flight Ctr, USRA, Code 662, Greenbelt, MD 20771 USA. RI Damineli, Augusto/D-8210-2012 OI Damineli, Augusto/0000-0002-7978-2994 NR 27 TC 2 Z9 2 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-003-X J9 ASTR SOC P PY 1999 VL 179 BP 46 EP 53 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN97L UT WOS:000083707900007 ER PT B AU Gull, TR Ishibashi, K Davidson, K AF Gull, TR Ishibashi, K Davidson, K CA Cycle 7 STIS GO Team BE Morse, JA Humphreys, RM Damineli, A TI First observations of eta Carinae with the Space Telescope Imaging Spectrograph SO ETA CARINAE AT THE MILLENNIUM SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on ETA Carinae at the Millennium CY JUL 19-23, 1998 CL GALLATIN GATEWAY, MT ID SPECTROSCOPY; SPECTRUM; CORE AB First observations of eta Carinae with the Space Telescope Imaging Spectrograph (STIS) aboard HST have been accomplished using a 52 " x 0." 1 aperture with a resolving power of 3,800 to 8,200 from 1640 Angstrom to 10400 Angstrom. At the angular resolution of 0." 1 (FWHM) for the two-pixel STIS CCD limit, the spatially-resolved spectra indicate that Component A is a well-defined point source down to 4000 Angstrom. Scattered light is detectable as far as the outer bounds of the Homunculus at longer wavelengths in the brighter stellar emission lines and continuum. Shortward of 4000 Angstrom, various line absorptions (mostly due to Fe II) inceasingly obscure direct view of Component A, but the highly modified stellar spectrum is easily detected by scattered light in the immediate vicinity. Faint point source emission resumes below 2100 Angstrom, but with very noticable scattered light close to Component A. Several nebular features are observed: H alpha and [N II] external to the Homunculus; the reflected spectrum of eta Carinae, especially in the P-Cygni-shaped Balmer lines; nebular Balmer-line absorption; scattered starlight very close to the star; a bright, ionized region within tao-arcsec rad;us of eta Carinae; and a very small, but bright, emission nebula within 0." 4 of Component A. Follow-up observations are scheduled with STIS GTO Cycle 8 time and are proposed for the Cycle 8 Guest Observer program for repeating these observations as eta Carinae changes in excitation. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Gull, TR (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. RI Gull, Theodore/D-2753-2012; Damineli, Augusto/D-8210-2012 OI Gull, Theodore/0000-0002-6851-5380; Damineli, Augusto/0000-0002-7978-2994 NR 16 TC 26 Z9 26 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-003-X J9 ASTR SOC P PY 1999 VL 179 BP 144 EP 154 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BN97L UT WOS:000083707900019 ER PT S AU Nicollier, C AF Nicollier, C GP EUROPEAN SPACE AGCY EUROPEAN SPACE AGCY TI Living and working in space SO EURO-ASIAN SPACE WEEK - CO-OPERATION IN SPACE: WHERE EAST & WEST FINALLY MEET SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT Euro-Asian Space Week on Cooperation in Space - Where East and West Finally Meet CY NOV 23-27, 1998 CL SINGAPORE, SINGAPORE SP European Space Agcy, Ctr Remote Imaging Sensing & Proc, Natl Univ Singapore, Reg Inst Environm Technol, CNES, Arianespace, ESCAP, SpotImage Spot Asia C1 NASA, Lyndon B Johnson Space Ctr, ESA, Houston, TX 77058 USA. RP Nicollier, C (reprint author), NASA, Lyndon B Johnson Space Ctr, ESA, Off Code CB, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-720-8 J9 ESA SP PUBL PY 1999 VL 430 BP 671 EP 676 PG 6 WC Engineering, Aerospace; Environmental Sciences; Remote Sensing; Telecommunications SC Engineering; Environmental Sciences & Ecology; Remote Sensing; Telecommunications GA BM89X UT WOS:000080057900088 ER PT S AU Laure, E Haines, M Mehrotra, P Zima, H AF Laure, E Haines, M Mehrotra, P Zima, H BE Amestoy, P Berger, P Dayde, M Duff, I Fraysse, V Giraud, L Ruiz, D TI Compiling data parallel tasks for coordinated execution SO EURO-PAR'99: PARALLEL PROCESSING SE Lecture Notes in Computer Science LA English DT Article; Proceedings Paper CT 5th International Euro-Par Conference CY AUG 31-SEP 03, 1999 CL TOULOUSE, FRANCE SP Ctr Europeen Rech & Format Avancee Calcul Sci, Ecole Natl Super Electr Electrotech Informat & Hydraul Toulouse, Inst Rech Inform AB Many advanced scientific applications are heterogeneous and multidisciplinary in nature, consisting of multiple, independent modules. Such applications require efficient means of coordination for their program units. The programming language Opus was designed recently to assist in coordinating the execution of multiple, independent program modules. In this paper we address the problem of how to compile an Opus program such that it can be efficiently executed on a broad class of machines. C1 Univ Vienna, Inst Software Technol & Parallel Syst, Vienna, Austria. Univ Wyoming, Dept Comp Sci, Laramie, WY 82071 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23665 USA. RP Univ Vienna, Inst Software Technol & Parallel Syst, Waehringer Guertel 18, Vienna, Austria. EM erwin@par.univie.ac.at; haines@uwyo.edu; pm@icase.edu; zima@par.univie.ac.at NR 7 TC 0 Z9 0 U1 0 U2 0 PU SPRINGER-VERLAG BERLIN PI BERLIN PA HEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANY SN 0302-9743 BN 3-540-66443-2 J9 LECT NOTES COMPUT SC PY 1999 VL 1685 BP 413 EP 417 PG 5 WC Computer Science, Theory & Methods SC Computer Science GA BQ96Y UT WOS:000165172300050 ER PT S AU Sawyer, W Takacs, L Molod, A Lucchesi, R AF Sawyer, W Takacs, L Molod, A Lucchesi, R BE Amestoy, P Berger, P Dayde, M Duff, I Fraysse, V Giraud, L Ruiz, D TI Modular Fortran 90 implementation of a parallel atmospheric general circulation model SO EURO-PAR'99: PARALLEL PROCESSING SE LECTURE NOTES IN COMPUTER SCIENCE LA English DT Article; Proceedings Paper CT 5th International Euro-Par Conference CY AUG 31-SEP 03, 1999 CL TOULOUSE, FRANCE SP Ctr Europeen Rech & Format Avancee Calcul Sci, Ecole Natl Super Electr Electrotech Informat & Hydraul Toulouse, Inst Rech Inform AB In this paper we present software engineering aspects of a parallel atmospheric General Circulation Model (GCM) currently nearing completion at the NASA Data Assimilation Office. The code is scientifically closely related to the current Goddard Earth Observing System (GEOS 2.x) GCM. The new software design, however, is a radical departure from the previous Fortran 77 code, using Fortran 90 derived data types and modules to compartmentalize the implementation. In order to reduce turnaround time needed to facilitate scientific development, the GEOS 3.x implementation uses a message-passing paradigm. This allows the performance to scale consistently to a large number of processors on both an Origin 2000 and a Gray T3E. The Message-Passing Interface (MPI) is used for portability. The modularity and performance of the parallel GEOS 3.x code allow faster development of scientific improvements such as variable resolution grids and a new land surface model which are key to keeping the GCM competitive with other leading models. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. RP Sawyer, W (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910 3, Greenbelt, MD 20771 USA. NR 17 TC 0 Z9 0 U1 0 U2 0 PU SPRINGER-VERLAG BERLIN PI BERLIN PA HEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANY SN 0302-9743 BN 3-540-66443-2 J9 LECT NOTES COMPUT SC PY 1999 VL 1685 BP 1403 EP 1410 PG 8 WC Computer Science, Theory & Methods SC Computer Science GA BQ96Y UT WOS:000165172300179 ER PT S AU Scharton, TD AF Scharton, TD GP EUROPEAN SPACE AGCY EUROPEAN SPACE AGCY TI In-flight measurements of dynamic force and comparison with methods used to derive force limits for ground vibration tests SO EUROPEAN CONFERENCE ON SPACECRAFT STRUCTURES, MATERIALS AND MECHANICAL TESTING, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT European Conference on Spacecraft Structures, Materials and Mechanical Testing CY NOV 04-06, 1998 CL BRAUNSCHWEIG, GERMANY SP European Space Agcy, CNES, DLR, DGLR AB In-flight measurements of the dynamic forces acting between an aerospace component and it's supporting structure have recently been obtained on the Advanced Composition Explorer (ACE) spacecraft. An improved vibration testing technique, in which the force applied to the test item by the shaker is limited to the interface force predicted in flight, has been developed and used in many NASA space programs [1-4]. Until recently there were no in-flight measurements of dynamic force to evaluate the methods of predicting the force limits being used in these tests. Comparison of the in-flight data and ground test data in this paper provides a validation of the methods currently being used for predicting the force limits. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Scharton, TD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 157-410, Pasadena, CA 91109 USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-712-7 J9 ESA SP PUBL PY 1999 VL 428 BP 583 EP 588 PG 6 WC Engineering, Aerospace; Engineering, Mechanical; Materials Science, Multidisciplinary; Materials Science, Characterization & Testing SC Engineering; Materials Science GA BM85X UT WOS:000079946900084 ER PT S AU Levine, MB Umland, JW Bruno, R Gutierrez, H AF Levine, MB Umland, JW Bruno, R Gutierrez, H GP EUROPEAN SPACE AGCY EUROPEAN SPACE AGCY TI Interferometry program flight experiment #1: Objectives and results. SO EUROPEAN CONFERENCE ON SPACECRAFT STRUCTURES, MATERIALS AND MECHANICAL TESTING, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT European Conference on Spacecraft Structures, Materials and Mechanical Testing CY NOV 04-06, 1998 CL BRAUNSCHWEIG, GERMANY SP European Space Agcy, CNES, DLR, DGLR AB The Interferometry Program EXperiments (IPEX) I and I! are a series of night experiments designed to characterize microdynamics of structures in space. These technology demonstration night experiments are precursors to the Space Interferometry Mission (SIM) which is schedule for a 2005 launch. Of particular concern is potential thermal snapping when space structures undergo rapid thermal variations such as a sun-to-shade transition. This information is needed to characterize uncontrolled high frequency disturbances in future space interferometry missions. Both experiments are performed on the German DARA/DASA free-flying platform Astro-Spas, which is sorties from the for a nominal 10-day mission. IPEX-I, performed during the STS-80 mission in December 1996, was a suite of 12 micro-g accelerometers which monitored the on-board dynamics of the Astro-Spas during normal operations and quiescent periods. The paper will report the results of the IPEX-I flight experiment. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Levine, MB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Dr,MS 157-316, Pasadena, CA 91109 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-712-7 J9 ESA SP PUBL PY 1999 VL 428 BP 589 EP 595 PG 7 WC Engineering, Aerospace; Engineering, Mechanical; Materials Science, Multidisciplinary; Materials Science, Characterization & Testing SC Engineering; Materials Science GA BM85X UT WOS:000079946900085 ER PT S AU Levine, MB AF Levine, MB GP EUROPEAN SPACE AGCY EUROPEAN SPACE AGCY TI On-orbit microdynamic boom characterization for space interferometry: IPEX II SO EUROPEAN CONFERENCE ON SPACECRAFT STRUCTURES, MATERIALS AND MECHANICAL TESTING, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT European Conference on Spacecraft Structures, Materials and Mechanical Testing CY NOV 04-06, 1998 CL BRAUNSCHWEIG, GERMANY SP European Space Agcy, CNES, DLR, DGLR AB The Interferometry Program EXperiments (IPEX) I and II are the first free-flying space experiments specifically designed to characterize the sub-micron microdynamic behavior of large flexible optical structures subjected to on-orbit themral-mechanical disturbances. These technology demonstration flight experiments are precursors to the IO-meter baseline Space Interferometry Mission (SIM) scheduled to launch in 2005, and will address the mission's nanometer-level structural stability requirements. Of particular interest is the existence of dynamic instability mechanisms within joints and materials due to sudden thermal variations (a.k.a. thermal snap), or other internal strain energy redistribution events. This information is needed to characterize potentially uncontrollable vibrational disturbances, and to validate structural designs and modeling approaches for joint-dominated extruding structures The data obtained from IPEX-II, performed aboard the,ASTRO-SPAS during the Space Shuttle STS-85 mission in August 1997, will be used to assess the characteristics of these dynamic instabilities on a real flight structure. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Levine, MB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 157-316, Pasadena, CA 91109 USA. NR 6 TC 0 Z9 0 U1 0 U2 1 PU EUROPEAN SPACE AGENCY PI PARIS PA 8-10 RUE MARIO NIKIS, 75738 PARIS, FRANCE SN 0379-6566 BN 92-9092-712-7 J9 ESA SP PUBL PY 1999 VL 428 BP 597 EP 602 PG 6 WC Engineering, Aerospace; Engineering, Mechanical; Materials Science, Multidisciplinary; Materials Science, Characterization & Testing SC Engineering; Materials Science GA BM85X UT WOS:000079946900086 ER PT J AU Rietmeijer, FJM Karner, JM Nuth, JA Wasilewski, PJ AF Rietmeijer, FJM Karner, JM Nuth, JA Wasilewski, PJ TI Nanoscale phase equilibrium in a triggered lightning-strike experiment SO EUROPEAN JOURNAL OF MINERALOGY LA English DT Article DE pyrometamorphism; fulgurites; triggered lightning experiment; experimental petrology; metastable equilibrium; mineralogy; analytical electron microscopy ID PYROMETAMORPHISM; ASSEMBLAGE; PYROXENE; ROCKS AB We describe the nanometer-sized phases in millimeter-sized spheres produced in a triggered lightning-strike experiment characterized by ultra-high heating of similar to 10(8) degrees s(-1) followed by similarly rapid quenching. The compositions of the aluminosilica glass spheres define a metastable Al2O3-SiO2 eutectic at similar to 40 wt. % Al2O3 The other phases are defined by the liquidus in the SiO2-Al2O3-Fe3O4 (wt %) phase diagram whereby hercynite formed at similar to 1750 degrees C and domains of Fe3+-rich cordierite glass that represent a ternary minimum melt at similar to 1400 degrees C with cotectic glasses linking this glass and spinel. Metastable eutectics are potentially important to understand the phase relationships due to flash heating events. C1 Univ New Mexico, Inst Meteorit, Albuquerque, NM 87131 USA. Univ New Mexico, Dept Earth & Planetary Sci, Albuquerque, NM 87131 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Rietmeijer, FJM (reprint author), Univ New Mexico, Inst Meteorit, Albuquerque, NM 87131 USA. RI Nuth, Joseph/E-7085-2012 NR 23 TC 9 Z9 9 U1 1 U2 2 PU E SCHWEIZERBARTSCHE VERLAGS PI STUTTGART PA NAEGELE U OBERMILLER JOHANNESSTRASSE 3A, D 70176 STUTTGART, GERMANY SN 0935-1221 J9 EUR J MINERAL JI Eur. J. Mineral. PD JAN-FEB PY 1999 VL 11 IS 1 BP 181 EP 186 PG 6 WC Mineralogy SC Mineralogy GA 166UY UT WOS:000078597000015 ER PT S AU O'Dell, SL Jones, WD Russell, JK Ramsey, BD Engelhaupt, D Cohen, LM Van Speybroeck, LP AF O'Dell, SL Jones, WD Russell, JK Ramsey, BD Engelhaupt, D Cohen, LM Van Speybroeck, LP BE Siegmund, OH Flanagan, KA TI Constellation-X Spectroscopy X-ray Telescope requirements and development program: MSFC research program SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE grazing-incidence optics; replicated optics; space missions; electroforming ID ASTROPHYSICS FACILITY AXAF AB The Constellation-X Spectroscopy X-ray Telescope (SXT) will provide high-throughput, high-resolution spectroscopy of cosmic sources, from 0.25 keV to 10 keV. Key to this capability is the development of large (1.6m diameter), lightweight optics for the SXT mirror assembly. Teams led by NASA's Marshall Space Flight Center (MSFC), by NASA's Goddard Space Flight Center (GSFC), and by Italy's Osservatorio Astronomico di Brera (OAB) are currently developing competing mirror technologies for this planned mission. Each team is making significant research progress in developing mirror technologies which satisfy the SXT requirements for lightweight optics, consistent with a system-level optical performance of better than 15 arcsec half-power diameter. The NASA Marshall Space Flight Center (MSFC), in collaboration with the Smithsonian Astrophysical Observatory (SAO), has focussed its efforts on full-shell replicated optics, of electroformed nickel alloys. Recent progress in identifying a surface treatment to effect low, controlled adhesion and, more significantly, in developing new high-strength nickel alloys make this a viable, low-cost approach to satisfying the SXT requirements. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP O'Dell, SL (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. OI O'Dell, Stephen/0000-0002-1868-8056 NR 14 TC 9 Z9 9 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 73 EP 81 DI 10.1117/12.366565 PG 9 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500008 ER PT S AU Stahle, CK Bandler, SR Barbee, T Beeman, J Brekosky, RP Cabrera, B Cunningham, M Deiker, S Figueroa-Feliciano, E Finkbeiner, FM Frank, M Gendreau, KC Haller, E Hilton, GC Irwin, KD Kelley, RL Labov, SE Li, MJ Madden, N Martinis, JM McCammon, D Nam, S Porter, FS Schnopper, H Silver, EH Szymkowiak, AE Tucker, GS Walker, A Wollman, DA AF Stahle, CK Bandler, SR Barbee, T Beeman, J Brekosky, RP Cabrera, B Cunningham, M Deiker, S Figueroa-Feliciano, E Finkbeiner, FM Frank, M Gendreau, KC Haller, E Hilton, GC Irwin, KD Kelley, RL Labov, SE Li, MJ Madden, N Martinis, JM McCammon, D Nam, S Porter, FS Schnopper, H Silver, EH Szymkowiak, AE Tucker, GS Walker, A Wollman, DA BE Siegmund, OH Flanagan, KA TI Toward a 2-eV microcalorimeter x-ray spectrometer for Constellation-X SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE Constellation-X; low temperature detector; microcalorimeter; spectroscopy; x-ray ID SUPERCONDUCTING TUNNEL-JUNCTIONS; HIGH-RESOLUTION; ELECTROTHERMAL FEEDBACK; PARTICLE DETECTORS AB Constellation-X is a cluster of identical observatories that together constitute a promising concept for a next-generation, high-throughput, high-resolution, astrophysical x-ray spectroscopy mission. The heart of the Constellation-X mission concept is a high-quantum-efficiency imaging spectrometer with 2 eV resolution at 6 keV. Collectively across the cluster, this imaging spectrometer will have twenty times the collecting efficiency of XRS on Astro-E and better than 0.25 are minute imaging resolution. The spectrometer on each satellite will be able to handle count rates of up to 1000 counts per second per imaging pixel for a point source and 30 counts per second per pixel for an extended source filling the array. Focal plane coverage of at least 2.5 are minutes x 2.5 are minutes, comparable to XRS but with a factor of thirty more pixels, is required. This paper will present the technologies that have the potential to meet all these requirements. It will identify the ones chosen for development for Constellation-X and explain why those were considered closer to realization, and it will summarize the results, of the development work thus far. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Stahle, CK (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Bandler, Simon/A-6258-2010; Porter, Frederick/D-3501-2012; Kelley, Richard/K-4474-2012; Frank, Matthias/O-9055-2014 OI Bandler, Simon/0000-0002-5112-8106; Porter, Frederick/0000-0002-6374-1119; NR 38 TC 21 Z9 21 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 82 EP 93 DI 10.1117/12.366490 PG 12 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500009 ER PT S AU Kelley, RL Audley, MD Boyce, KR Breon, SR Fujimoto, R Gendreau, KC Holt, SS Ishisaki, Y McCammon, D Mihara, T Mitsuda, K Moseley, SH Mott, DB Porter, FS Stahle, CK Szymkowiak, AE AF Kelley, RL Audley, MD Boyce, KR Breon, SR Fujimoto, R Gendreau, KC Holt, SS Ishisaki, Y McCammon, D Mihara, T Mitsuda, K Moseley, SH Mott, DB Porter, FS Stahle, CK Szymkowiak, AE BE Siegmund, OH Flanagan, KA TI The Astro-E High Resolution X-ray Spectrometer SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE detectors; calorimeters; bolometers; x-ray; spectrometer; instruments; missions AB The Astro-E High Resolution X-ray Spectrometer (XRS) was developed jointly by the NASA/Goddard Space Flight Center and the Institute of Space and Astronautical Science in Japan. The instrument is based on a new approach to spectroscopy, the X-ray microcalorimeter. This device senses the energies of individual X-ray photons as heat with extreme precision. A 32 channel array of microcalorimeters is being employed, each with an energy resolution of about 12 eV at 6 keV (the Fe-K region). This will provide spectral resolving power 10 times higher than any other non;dispersive X-ray spectrometer. The instrument incorporates a three stage cooling system capable of operating the array at 60 mK for about two years in orbit. The array sits at the focus of a grazing incidence conical mirror. The quantum efficiency of the microcalorimeters and the reflectivity of the X-ray mirror system combine to give high throughput over the 0.3-12 keV energy band. This new capability will enable the study of a wide range of high-energy astrophysical sources with unprecedented spectral sensitivity. This paper presents the basic design requirements and implementation of the XRS, and also describes the instrument parameters and performance. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kelley, RL (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Porter, Frederick/D-3501-2012; Kelley, Richard/K-4474-2012 OI Porter, Frederick/0000-0002-6374-1119; NR 21 TC 43 Z9 43 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 114 EP 127 DI 10.1117/12.366493 PG 14 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500012 ER PT S AU Stahle, CK Audley, MD Boyce, KR Brekosky, RP Fujimoto, R Gendreau, KC Gygax, JD Ishisaki, Y Kelley, RL Clanahan, RA Mihara, T Mitsuda, K Moseley, SH Mott, DB Porter, FS Stahle, CM Szymkowiak, AE AF Stahle, CK Audley, MD Boyce, KR Brekosky, RP Fujimoto, R Gendreau, KC Gygax, JD Ishisaki, Y Kelley, RL Clanahan, RA Mihara, T Mitsuda, K Moseley, SH Mott, DB Porter, FS Stahle, CM Szymkowiak, AE BE Siegmund, OH Flanagan, KA TI Design and performance of the Astro-E/XRS microcalorimeter array and anti-coincidence detector SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE XRS; Astro-E; microcalorimeter; spectroscopy; x-ray ID HOPPING CONDUCTION; DOPED SILICON; RAY; THERMALIZATION AB The XRS instrument has an array of 32 micro-calorimeters at the focal plane. These calorimeters consist of ion-implanted silicon thermistors and HgTe thermalizing x-ray absorbers. These devices have demonstrated a resolution of 9 eV at 3 keV and II eV at 6 keV. We will discuss the basic physical parameters of this array, including the array layout, thermal conductance of the link to the heat sink, operating temperature, thermistor size, absorber choice, and means of attaching the absorber to the thermistor bearing element. We will present representative performance data, though a more detailed presentation of the results of the instrument calibration is presented elsewhere in these proceedings. A silicon ionization detector is located behind the calorimeter array and serves to reject events due to cosmic rays. We will briefly describe this anti-coincidence detector and its performance in conjunction with the array. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Stahle, CK (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Porter, Frederick/D-3501-2012; Kelley, Richard/K-4474-2012 OI Porter, Frederick/0000-0002-6374-1119; NR 15 TC 13 Z9 13 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 128 EP 136 DI 10.1117/12.366494 PG 9 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500013 ER PT S AU Auchere, F Hassler, DM Slater, D Woods, TN AF Auchere, F Hassler, DM Slater, D Woods, TN BE Siegmund, OH Flanagan, KA TI SwRI/LASP sounding rocket inter-calibration with the EIT instrument on board SoHO SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE EUV instruments; CCD aging; instrumental response ID MISSION AB Two successful sounding rocket flights were launched on May 15, 1997 and November 2, 1998 with an objective of providing inter-calibration with several of the instruments on board SoHO and TRACE. We will discuss here the results of the inter-calibration between the SwRI/LASP rocket imaging instruments and the Extreme-ultraviolet Imaging Telescope (EIT) on SoHO. The Multiple XUV Imager (MXUVI) sounding rocket instrument is a multi-layer mirror telescope equiped with a special internal occulter and light trap to provide full disk images of Fe IX/X 17.1 nm and off-limb observations of He II 30.4 nm. The SoHO/EIT instrument is also a full disk multi-layer imager with four channels, Fe IX/X 17.1 nm, Fe XII 19.5 nm, Fe XV 28.4 nm and He II 30.4 nm. By comparison with the EIT observations taken at the same time we can quantify the sensitivity degradation of the EIT detector, as well as measure the off-limb stray-light characteristics of the two instruments. C1 NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. RP Auchere, F (reprint author), NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 351 EP 359 DI 10.1117/12.366516 PG 9 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500034 ER PT S AU Austin, RA Ramsey, BD Tse, CL Zirnstein, CG AF Austin, RA Ramsey, BD Tse, CL Zirnstein, CG BE Siegmund, OH Flanagan, KA TI A high-pressure gas-scintillation-proportional counter for the focus of a hard-x-ray telescope SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE X-ray; astronomy; GSPC; proportional counter; imaging; telescope AB We are developing a high-pressure Gas Scintillation Proportional Counter (GSPC) for the focus of a balloon-borne hard-xray telescope. The device has a total active diameter of 50 mm, of which the central 20 mm only is used, and is filled with xenon + 4% helium at a total pressure of 10(6) Pa giving a quantum efficiency of greater than 85% up to 60 keV. The detector entrance is sealed with a beryllium window, 3-mm thick, which provides useful transmission down to 6 keV, well below the atmospheric cut-off at balloon float altitudes. Scintillation: light exits the detector via a UV transmitting window in its base and is registered by a Hamamatsu position-sensitive crossed-grid-readout photomultiplier tube. Initial testing is underway and preliminary measurements of light yield, energy resolution and spatial resolution will be reported. Simulations show that a spatial resolution of 0.5 mm FWHM or better should be achievable up to 60 keV, and this is well matched to the angular resolution and plate scale of the mirror system. The energy resolution has been measured to be around 5% at 22 keV. Full details of the instrument design and its performance will be presented. A first flight is scheduled for the Fall of 99, on a stratospheric balloon to be launched from Fort Sumner, New Mexico. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Austin, RA (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. NR 2 TC 5 Z9 5 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 714 EP 720 DI 10.1117/12.366553 PG 7 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500070 ER PT S AU Porter, FS Audley, MD Brekosky, RP Derro, RJ Dipirro, MJ Gendreau, KC Gygax, JD Kelley, RL McCammon, D Morell, A Murphy, SD Paulos, RJ Pham, T Stahle, CK Szymkowiak, AE Tuttle, JG AF Porter, FS Audley, MD Brekosky, RP Derro, RJ Dipirro, MJ Gendreau, KC Gygax, JD Kelley, RL McCammon, D Morell, A Murphy, SD Paulos, RJ Pham, T Stahle, CK Szymkowiak, AE Tuttle, JG BE Siegmund, OH Flanagan, KA TI The detector assembly and the ultra low temperature refrigerator for XRS SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE X-ray; calorimeter; ADR; XRS; ASTRO-E; low temperature AB The X-ray spectrometer (XRS) on the Japanese Astro-E observatory is the first ultra low temperature space borne instrument. The system utilizes a 900g ferric ammonium alum (FAA) adiabatic demagnetization refrigerator (ADR) with He-3 gas gap heat switch to cool the detector assembly to 0.060 K. The system operates in a "single shot" configuration allowing the system to remain at its operating temperature for about 40 hours in the lab before executing a recharge cycle. The on-orbit performance is expected to be about 36 hours with a 97% duty cycle. The detector assembly for XRS consists of a 32 channel microcalorimeter array, bias electronics, thermometry, and an anti-coincidence detector that are attached to the cold stage of the ADR. To thermally isolate the detector system from the superfluid helium reservoir, the detector system is suspended by Kevlar(1) cords and electrical connection is made by 130, 20 micron diameter, tensioned NbTi leads. The detectors are read out in a source-follower arrangement using FET amplifiers operating at 130 K mounted in nested, thermally-isolated assemblies that also use Kevlar suspension and stainless steel wiring. The design and thermal performance of this system will be discussed. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Porter, FS (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Porter, Frederick/D-3501-2012; Kelley, Richard/K-4474-2012 OI Porter, Frederick/0000-0002-6374-1119; NR 9 TC 20 Z9 20 U1 1 U2 2 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 729 EP 740 DI 10.1117/12.366556 PG 12 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500072 ER PT S AU Boyce, KR Audley, MD Baker, RG Dumonthier, JJ Fujimoto, R Gendreau, KC Ishisaki, Y Kelley, RL Stahle, CK Szymkowiak, AE Winkert, GE AF Boyce, KR Audley, MD Baker, RG Dumonthier, JJ Fujimoto, R Gendreau, KC Ishisaki, Y Kelley, RL Stahle, CK Szymkowiak, AE Winkert, GE BE Siegmund, OH Flanagan, KA TI Design and performance of the Astro-E/XRS signal processing system SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE X-ray astronomy; pulse detection; digital signal processing; XRS; ASTRO-E AB We describe the signal processing system of the Astro-E XRS instrument.(1) The Calorimeter Analog Processor (CAP) provides bias and power for the detectors and amplifies the detector signals by a factor of 20,000. The Calorimeter Digital Processor (CDP) performs the digital processing of the calorimeter signals, detecting X-ray pulses and analyzing them by optimal filtering. We describe the operation of pulse detection, pulse height analysis, and risetime determination. We also discuss performance, including the three event grades (hi-res, mid-res, and low-res), anticoincidence detection, counting rate dependence, and noise rejection. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Boyce, KR (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Kelley, Richard/K-4474-2012 NR 4 TC 34 Z9 34 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 741 EP 750 DI 10.1117/12.366557 PG 10 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500073 ER PT S AU Ramsey, BD Engelhaupt, D Speegle, CO O'Dell, SL Austin, RA Kolodziejczak, JJ Weisskopf, MC AF Ramsey, BD Engelhaupt, D Speegle, CO O'Dell, SL Austin, RA Kolodziejczak, JJ Weisskopf, MC BE Siegmund, OH Flanagan, KA TI The HERO Program, high-energy replicated optics for a hard-x-ray balloon payload SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE x ray; telescope; optics; replicated; balloon AB We are developing high-energy replicated optics for a balloon-bome hard-x-ray telescope. When completed, the telescope will have around 130 cm(2) of effective collecting area at 60 keV, and an angular resolution of less than or equal to 30 are seconds, half power diameter. With an array of gas scintillation proportional counters in the focal plane the payload will provide unprecedented sensitivity for pointed observations in the hard-x-ray band. We present an overview of the HERO program, together with test data from the first mirror shell. The overall sensitivity of the full payload is given for planned long- and ultra-long-duration balloon flights. C1 NASA, MSFC, Dept Space Sci, Huntsville, AL 35812 USA. RP Ramsey, BD (reprint author), NASA, MSFC, Dept Space Sci, Huntsville, AL 35812 USA. NR 6 TC 7 Z9 7 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 816 EP 821 DI 10.1117/12.366569 PG 6 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500081 ER PT S AU Sharma, DP Ramsey, BD Meisner, J Austin, RA Sipila, H Gostilo, V Ivanov, V Loupilov, A Sokolov, A AF Sharma, DP Ramsey, BD Meisner, J Austin, RA Sipila, H Gostilo, V Ivanov, V Loupilov, A Sokolov, A BE Siegmund, OH Flanagan, KA TI Preliminary results from small-pixel CdZnTe arrays SO EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X CY JUL 21-23, 1999 CL DENVER, CO SP SPIE DE cadmium-zinc-telluride; pixellated detectors AB We have evaluated 2 small-pixel (0,65 mm) Cadmium-Zinc-Telluride arrays with thickness of 1 and 2 mm that were fabricated for MSFC by Metorex and Baltic Science Institute (Riga, Latvia). Each array was optimised for temperature and collection bias and was then exposed to Cadmium(109), Am-241 and Fe-55 laboratory isotopes to measure the energy resolution for each pixel. The arrays were then scanned with a finely-collimated X-ray beam, of width 100 micron, to examine pixel to pixel. and inter-pixel charge collection efficiency. Preliminary results from the array tests are presented. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. RP Sharma, DP (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. NR 0 TC 4 Z9 4 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3251-2 J9 P SOC PHOTO-OPT INS PY 1999 VL 3765 BP 822 EP 832 DI 10.1117/12.366570 PG 11 WC Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BP12E UT WOS:000084180500082 ER PT J AU Bely, P Petro, L Burg, R Wade, L Beichman, C Gay, J Baudoz, P Rabbia, Y Perrin, JM AF Bely, P Petro, L Burg, R Wade, L Beichman, C Gay, J Baudoz, P Rabbia, Y Perrin, JM TI The exo-zodiacal disk mapper: A space interferometer to detect and map zodiacal dust disks around nearby stars SO EXPERIMENTAL ASTRONOMY LA English DT Article DE circumstellar disks; coronagraph; space telescopes; zodiacal dust disks ID ROTATION SHEARING INTERFEROMETER; INTERPLANETARY DUST; LIGHT; PIONEER-10; NGST AB We present a concept for a space mission designed to make a mid-IR survey of potential zodiacal dust disks around nearby stars. We show that a two-aperture (0.6 m diameter), 10-m baseline, nulling interferometer located in a 1 x 4 AU, 4-yr solar orbit would allow for the survey of 400 stars in the solar neighborhood and permit a first-order determination of the disk inclination and radial dependences of density and temperature. The high dynamic range of the instrument may also be used to study additional astrophysical phenomena. Beyond its own scientific merit, such a mission would serve as a technological precursor to a larger interferometer of the type being considered for the detection of earth-like planets. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Baltimore, MD 21218 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Observ Cote Azur, Caussols, France. Observ Haute Provence, F-04870 St Michel, France. RP Bely, P (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. NR 30 TC 2 Z9 2 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0922-6435 J9 EXP ASTRON JI Exp. Astron. PY 1999 VL 9 IS 4 BP 189 EP 204 DI 10.1023/A:1008040902533 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 267HX UT WOS:000084353500001 ER PT S AU Bussoletti, E Colangeli, L Moreno, JJL Epifani, E Mennella, V Palomba, E Palumbo, P Rotundi, A Vergara, S Girela, F Herranz, M Jeronimo, JM Lopez-Jimenez, AC Molina, A Moreno, F Olivares, I Rodrigo, R Rodriguez-Gomez, JF Sanchez, J Mc Donnell, JAM Leese, M Lamy, P Perruchot, S Crifo, JF Fulle, M Perrin, JM Angrilli, F Benini, E Casini, L Cherubini, G Coradini, A Giovane, F Grun, E Gustafson, B Maag, C Weissmann, PR AF Bussoletti, E Colangeli, L Moreno, JJL Epifani, E Mennella, V Palomba, E Palumbo, P Rotundi, A Vergara, S Girela, F Herranz, M Jeronimo, JM Lopez-Jimenez, AC Molina, A Moreno, F Olivares, I Rodrigo, R Rodriguez-Gomez, JF Sanchez, J Mc Donnell, JAM Leese, M Lamy, P Perruchot, S Crifo, JF Fulle, M Perrin, JM Angrilli, F Benini, E Casini, L Cherubini, G Coradini, A Giovane, F Grun, E Gustafson, B Maag, C Weissmann, PR BE Lamy, P Thomas, N TI The GIADA experiment for ROSETTA mission to comet 46P/Wirtanen: Design and performances SO EXPLORATION OF SMALL BODIES IN THE SOLAR SYSTEM: I. INITIAL RESULTS AND FUTURE PROSPECTS SE ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article; Proceedings Paper CT B1 1 Symposium of COSPAR Scientific Commission B Held at the 32nd COSPAR Scientific Assembly CY JUL 12-19, 1998 CL NAGOYA, JAPAN SP Comm Space Res, Int Astron Union, European Space Agcy, NASA ID DUST FLUX; SIMULATION AB Rosetta is one of the most ambitious missions planned by ESA for the beginning of the next millennium. It will explore from very close a comet nucleus along its trajectory up to perihelion. In the instrument complex forming the scientific payload, the GIADA (Grain Impact Analyser and Dust Accumulator) experiment is devoted to study the cometary dust flux evolution and grain dynamic properties. To achieve the required performances and the expected scientific return, GIADA has been designed as a multi-sensor instrument. It is able to detect grain passage by laser light scattering measurement, particle momentum through piezoelectric transducers and mass flux by means of quartz crystal microbalances. In this paper we describe the technical solutions and performances which have been reached on the development models of GIADA. (C) 1999 COSPAR. Published by Elsevier Science Ltd. C1 Univ Navale, Ist Fis Sperimentale, I-80133 Naples, Italy. Osserv Astron Capodimonte, I-80131 Naples, Italy. CSIC, Inst Astrofis Andalucia, Granada 18080, Spain. Univ Naples Federico 2, Dipartimento Ingn Aerospaziale, I-80100 Naples, Italy. Univ Granada, Granada 18080, Spain. Univ Kent, Unit Space Sci, Canterbury CT2 7NR, Kent, England. Astron Spatiale Lab, F-13376 Marseille, France. CNRS, Serv Aeron, F-91371 Verrieres Le Buisson, France. Osserv Astron Trieste, I-34131 Trieste, Italy. Observ Haute Provence, F-04870 St Michel, France. CISAS, Dipartimento Ingn Meccan, I-35131 Padua, Italy. Officine Galileo, I-50013 Florence, Italy. CNR, Reparto Planetol, IAs, I-00198 Rome, Italy. NASA HQ, Code SZ, Washington, DC USA. Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. T&M Engn, Cape Canaveral, FL 32920 USA. Jet Propuls Lab, Pasadena, CA 91109 USA. RP Bussoletti, E (reprint author), Univ Navale, Ist Fis Sperimentale, Via A Gasperi 5, I-80133 Naples, Italy. RI Gustafson, Bo/B-9526-2011; Benini, Ernesto/A-6834-2012; Lopez Jimenez, Antonio C./L-4738-2014; Herranz De La Revilla, Miguel Luis/L-5991-2014; OI fulle, marco/0000-0001-8435-5287; Palomba, Ernesto/0000-0002-9101-6774; Moreno, Fernando/0000-0003-0670-356X; Benini, Ernesto/0000-0002-5061-4284; Lopez Jimenez, Antonio C./0000-0002-6297-0681; Herranz De La Revilla, Miguel Luis/0000-0003-4343-6632; Rodriguez-Gomez, Julio F./0000-0002-6757-5912; Lopez-Moreno, Jose Juan/0000-0002-7946-2624; Rotundi, Alessandra/0000-0001-5467-157X NR 11 TC 9 Z9 9 U1 2 U2 2 PU PERGAMON PRESS LTD PI OXFORD PA THE BOULEVARD LANGFORD LANE KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0273-1177 J9 ADV SPACE RES-SERIES PY 1999 VL 24 IS 9 BP 1139 EP 1148 DI 10.1016/S0273-1177(99)80207-5 PG 10 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BP29D UT WOS:000084578600007 ER PT S AU Starr, R Clark, PE Evans, LG Floyd, SR McClanahan, TP Trombka, JI Boynton, WV Bailey, S Bruckner, J Squyres, SW Goldsten, JO McNutt, RL AF Starr, R Clark, PE Evans, LG Floyd, SR McClanahan, TP Trombka, JI Boynton, WV Bailey, S Bruckner, J Squyres, SW Goldsten, JO McNutt, RL BE Lamy, P Thomas, N TI Cruise measurements taken with the near XGRS SO EXPLORATION OF SMALL BODIES IN THE SOLAR SYSTEM: I. INITIAL RESULTS AND FUTURE PROSPECTS SE ADVANCES IN SPACE RESEARCH LA English DT Article; Proceedings Paper CT B1 1 Symposium of COSPAR Scientific Commission B Held at the 32nd COSPAR Scientific Assembly CY JUL 12-19, 1998 CL NAGOYA, JAPAN SP Comm Space Res, Int Astron Union, European Space Agcy, NASA ID RAY SPECTROMETER AB The X-ray/Gamma-ray Spectrometer on the Near Earth Asteroid Rendezvous spacecraft will remotely detect characteristic x-ray and gamma-ray emissions from the surface of 433 Eros to develop global maps of the elemental composition of the asteroid surface. Solar excited x-ray fluorescence in the 1 to 10 keV range will be used to measure the surface abundances of Mg, Al, Si, Ca, Ti, and Fe with spatial resolutions down to 2 km. Gamma-ray emissions in the 0.1 to 10 MeV range will be used to measure cosmic-ray excited emissions from such elements as O, Si, Fe,and H as well as naturally radioactive elements K, Th, and U to surface depths on the order of 10 cm. In-flight calibrations are essential to the understanding and analysis of data collected at Eros. (C) 1999 COSPAR. Published by Elsevier Science Ltd. C1 Catholic Univ Amer, Washington, DC 20064 USA. Comp Sci Corp, Laurel, MD 20707 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Arizona, Tucson, AZ 85721 USA. Max Planck Inst Chem, Mainz, Germany. Cornell Univ, Ithaca, NY 14853 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RP Starr, R (reprint author), Catholic Univ Amer, Washington, DC 20064 USA. RI McNutt, Ralph/E-8006-2010 OI McNutt, Ralph/0000-0002-4722-9166 NR 5 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON PRESS LTD PI OXFORD PA THE BOULEVARD LANGFORD LANE KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0273-1177 J9 ADV SPACE RES PY 1999 VL 24 IS 9 BP 1159 EP 1162 DI 10.1016/S0273-1177(99)80209-9 PG 4 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BP29D UT WOS:000084578600009 ER PT S AU Huebner, WF Benkhoff, J Capria, MT Coradini, A De Sanctis, MC Enzian, A Orosei, R Prialnik, D AF Huebner, WF Benkhoff, J Capria, MT Coradini, A De Sanctis, MC Enzian, A Orosei, R Prialnik, D BE LevasseurRegourd, AC Worms, JC Mohlmann, D Klinger, J TI Results from the comet nucleus model team at the International Space Science Institute, Bern, Switzerland SO EXPLORATION OF SMALL BODIES IN THE SOLAR SYSTEM: RELATED LABORATORY AND MODELLING STUDIES SE ADVANCES IN SPACE RESEARCH LA English DT Article; Proceedings Paper CT B1 2 and B1 3 Symposia of COSPAR Scientific Commission B on Exploration of Small Bodies in the Solar System, at the 32nd COSPAR Scientific Assembly CY JUL 12-19, 1998 CL NAGOYA, JAPAN SP Comm Space Res, Int Astron Union, European Space Agcy, NASA, Natl Space Dev Agcy Japan, Agenzia Spaziale Italiana AB Five one-dimensional algorithms for heat and gas transport in porous icy bodies have been applied, each to four simplified compositions of comet nucleus models: (1) pure H2O ice, (2) a mixture of H2O and CO ices, (3) a mixture of H2O ice and dust, and (4) a mixture of H2O and CO ices and dust. Ln addition, two different pore radii were assumed in models 3 and 4, The algorithms were chosen on the basis of recent applications and independent code development and evolution. A sixth algorithm was used only in a few models. Results for a spinning comet nucleus in the orbit of Comet 46P/Wirtanen were compared to establish credibility for the five algorithms. Discrepancies in results were discussed and isolated for possible causes. The algorithms were then investigated and modified by the presenting team members. After resolution of major differences from the simple models, each team member will be able to address more complex models of their own choosing with greater confidence. These models will include investigations of the effects of amorphous versus crystalline water ice, trapped gases versus frozen gases, multi-dimensional calculations, and dust mantle development and removal. Results and progress on the algorithms, and plans for further development are discussed. (C) 1999 COSPAR. Published by Elsevier Science Ltd. C1 SW Res Inst, San Antonio, TX 78228 USA. DLR, Inst Planetenerkundung, D-12489 Berlin, Germany. CNR, Ist Astrofis Spaziale, I-00133 Rome, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Tel Aviv Univ, Dept Geophys & Planetary Sci, IL-69978 Ramat Aviv, Israel. RP Huebner, WF (reprint author), SW Res Inst, PO Drawer 28510, San Antonio, TX 78228 USA. RI De Sanctis, Maria Cristina/G-5232-2013; OI De Sanctis, Maria Cristina/0000-0002-3463-4437; capria, maria teresa/0000-0002-9814-9588 NR 8 TC 14 Z9 14 U1 1 U2 1 PU PERGAMON PRESS LTD PI OXFORD PA THE BOULEVARD LANGFORD LANE KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0273-1177 J9 ADV SPACE RES PY 1999 VL 23 IS 7 BP 1283 EP 1298 DI 10.1016/S0273-1177(99)00040-X PG 16 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BN23W UT WOS:000081222500017 ER PT J AU Alexander, M McKendrick Nesbitt Casavecchia Kawasaki Cartechini Aoiz de Miranda Ashfold Schatz Vasyutinskii Auerbach Progrebnya Simons Connor Whiteley Leone Gordon Stolte Clary Smith Levine Zare Torres Baugh Miller AF Alexander, M McKendrick Nesbitt Casavecchia Kawasaki Cartechini Aoiz de Miranda Ashfold Schatz Vasyutinskii Auerbach Progrebnya Simons Connor Whiteley Leone Gordon Stolte Clary Smith Levine Zare Torres Baugh Miller TI General discussion SO FARADAY DISCUSSIONS LA English DT Editorial Material ID POTENTIAL-ENERGY SURFACES; CONTROLLING BIMOLECULAR REACTIONS; DIFFERENTIAL CROSS-SECTIONS; MOLECULAR-BEAM EXPERIMENTS; BOND SELECTED REACTION; GAS-PHASE REACTIONS; OPEN-SHELL SYSTEMS; F+H-2->HF+H REACTION; 4-ATOM REACTIONS; O(P-3(J))+HYDROCARBON REACTIONS C1 Univ Perugia, I-06100 Perugia, Italy. Univ Complutense Madrid, E-28040 Madrid, Spain. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Minnesota, Minneapolis, MN USA. Univ Bordeaux, Bordeaux, France. UCL, London WC1E 6BT, England. Vrije Univ Amsterdam, Amsterdam, Netherlands. FOM Inst Amsterdam, Amsterdam, Netherlands. IBM Corp, Res Ctr, San Jose, CA USA. Leiden Univ, NL-2300 RA Leiden, Netherlands. NR 103 TC 5 Z9 5 U1 0 U2 3 PU ROYAL SOC CHEMISTRY PI CAMBRIDGE PA THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND SN 1364-5498 J9 FARADAY DISCUSS JI Faraday Discuss. PY 1999 VL 113 BP 201 EP 239 PG 39 WC Chemistry, Physical SC Chemistry GA 249LH UT WOS:000083334200013 ER PT B AU Newman, JC Harris, CE Piascik, RS Dawicke, DS AF Newman, JC Harris, CE Piascik, RS Dawicke, DS BE Wu, XR Wang, ZG TI Methodology for predicting the onset of widespread fatigue damage in Lap-splice joints and structure SO FATIGUE '99: PROCEEDINGS OF THE SEVENTH INTERNATIONAL FATIGUE CONGRESS, VOLS 1-4 LA English DT Proceedings Paper CT 7th International Fatigue Congress (Fatigue '99) CY JUN 08-12, 1999 CL Beijing, PEOPLES R CHINA SP Beijing Inst Aeronaut Mat, Inst Met Res, Fatigue Soc, C-MRS, Int Fatigue Congress, Nat Sci Fdn China, C-MRS, MTS Syst Corp, INSTRON Int Ltd, AFOSR AOARD, USARO-FE, Roell Amsler, NCode Int Ltd, United Technol Corp, European Commiss, European Union-Delegat AB NASA has conducted an Airframe Structural Integrity Program to develop the methodology to predict the onset of widespread fatigue damage in lap-splice joints of fuselage structures. Several stress analysis codes have been developed or enhanced to analyze the lap-splice-joint configuration. Fatigue lives in lap-splice-joint specimens and fatigue-crack growth in a structural fatigue test article agreed well with calculations from small-crack theory and fatigue-crack-growth analyses with the FASTRAN code. Residual-strength analyses of laboratory specimens and wide stiffened panels were predicted quite well from the critical crack-tip-opening angle (CTOA) fracture criterion and elastic-plastic finite-element analyses (two- or three-dimensional codes and the STAGS shell code). C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Newman, JC (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 21 TC 0 Z9 0 U1 1 U2 1 PU CHINA HIGHER EDUCATION PRESS BEIJING PI BEIJING PA 55 SHATAN HOUJIE, BEIJING, PEOPLES R CHINA BN 7-04-007582-2 PY 1999 BP 81 EP 92 PG 12 WC Engineering, Mechanical SC Engineering GA BR59R UT WOS:000166896200006 ER PT B AU Piascik, RS AF Piascik, RS BE Wu, XR Wang, ZG TI The growth of small corrosion fatigue cracks in alloy 7050 SO FATIGUE '99: PROCEEDINGS OF THE SEVENTH INTERNATIONAL FATIGUE CONGRESS, VOLS 1-4 LA English DT Proceedings Paper CT 7th International Fatigue Congress (Fatigue '99) CY JUN 08-12, 1999 CL Beijing, PEOPLES R CHINA SP Beijing Inst Aeronaut Mat, Inst Met Res, Fatigue Soc, C-MRS, Int Fatigue Congress, Nat Sci Fdn China, C-MRS, MTS Syst Corp, INSTRON Int Ltd, AFOSR AOARD, USARO-FE, Roell Amsler, NCode Int Ltd, United Technol Corp, European Commiss, European Union-Delegat AB The corrosion fatigue crack growth characteristics of small (>35 mum) surface and corner cracks in aluminum alloy 7075 is established. The early stage of crack growth is studied by performing in situ long focal length microscope (500X) crack length measurements in laboratory air and 1% NaCl environments. To quantify the "small crack effect" in the corrosive environment, the corrosion fatigue crack propagation behavior of small cracks is compared to long through-the-thickness cracks grown under identical experimental conditions. In salt water, long crack constant K-max growth rates are similar to small crack da/dN. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Piascik, RS (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 6 TC 0 Z9 0 U1 0 U2 2 PU CHINA HIGHER EDUCATION PRESS BEIJING PI BEIJING PA 55 SHATAN HOUJIE, BEIJING, PEOPLES R CHINA BN 7-04-007582-2 PY 1999 BP 2237 EP 2242 PG 6 WC Engineering, Mechanical SC Engineering GA BR59R UT WOS:000166896200337 ER PT S AU Seshadri, BR Newman, JC AF Seshadri, BR Newman, JC BE Panontin, TL Sheppard, SD TI Analyses of buckling and stable tearing in thin-sheet materials SO FATIGUE AND FRACTURE MECHANICS: TWENTY-NINTH VOLUME SE AMERICAN SOCIETY FOR TESTING AND MATERIALS SPECIAL TECHNICAL PUBLICATION LA English DT Proceedings Paper CT 29th National Symposium on Fatigue and Fracture Mechanics CY JUN 24-26, 1997 CL STANFORD, CA SP ASTM Comm E8 Fatigue & Fracture DE cracks; crack growth; crack-tip-opening angle (CTOA); buckling; multiple-site damage cracking; STAGS shell code AB The purpose of this paper was to verify the capability of the STAGS (general shell, geometric and material nonlinear) code and the critical crack-tip-opening angle (CTOA) fracture criterion to predict stable tearing in cracked panels that fail with severe out-of-plane buckling. Materials considered in the analyses ranged from brittle to ductile behavior. Experimental test data used in this study are reported elsewhere. The STAGS code was used to model stable tearing using a critical CTOA value that was determined from a cracked panel that was "restrained" from buckling. The STAGS code and the critical CTOA were then used to predict the influence of buckling on stable tearing and failure loads. Parameters like crack-length-to-specimen-width ratio, crack configuration, thickness, and material tensile properties had a significant influence on the buckling behavior of cracked thin-sheet materials. Experimental and predicted results showed a varied buckling response for different crack-length-to-sheet-thickness ratios because different buckling modes were activated. The effects of material tensile properties and fracture toughness on buckling response were presented and discussed. The STAGS code and the CTOA fracture criterion were able to predict the influence of buckling on stable tearing behavior and failure loads on a variety of materials and crack configurations. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Seshadri, BR (reprint author), NASA, Langley Res Ctr, MS 188E, Hampton, VA 23681 USA. NR 16 TC 3 Z9 3 U1 0 U2 0 PU AMERICAN SOCIETY TESTING AND MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DRIVE, W CONSHOHOCKEN, PA 19428-2959 USA SN 1040-1695 BN 0-8031-2486-4 J9 AM SOC TEST MATER PY 1999 VL 1332 BP 114 EP 134 DI 10.1520/STP14946S PG 21 WC Engineering, Mechanical; Mechanics; Metallurgy & Metallurgical Engineering SC Engineering; Mechanics; Metallurgy & Metallurgical Engineering GA BM73J UT WOS:000079623500007 ER EF