FN Thomson Reuters Web of Science™ VR 1.0 PT J AU KLEB, WL WEILMUENSTER, KJ AF KLEB, WL WEILMUENSTER, KJ TI HIGH ANGLE-OF-ATTACK INVISCID SHUTTLE ORBITER COMPUTATION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note RP KLEB, WL (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 7 TC 0 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1992 VL 29 IS 5 BP 746 EP 748 DI 10.2514/3.11520 PG 3 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700021 ER PT J AU KALU, EE WHITE, RE DARCY, EC AF KALU, EE WHITE, RE DARCY, EC TI MEASUREMENTS OF THE FUNDAMENTAL THERMODYNAMIC PARAMETERS OF LI/BCX AND LI/SOCL2 CELLS SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article AB The thermodynamic data needed to estimate the heat generation characteristics of Li/BCX and Li/SOCl2 cells were determined using two experimental techniques, equilibrium or reversible cell discharge and measurement of open circuit potential as a function of temperature. The results obtained showed that the reversible cell potential (E(r)), the temperature dependence of the reversible cell potential (dE(r)/dT) and thermoneutral potential (E(h)) of the BCX cell were respectively, E(r,25oc) = 3.74 V, dE(r)/dT = -0.857 +/- 0.198 mV/K and E(h) = 3.994 +/- 0.0603 V. The respective values obtained for the Li/SOCl2 cell were E(r,25oc) = 3.67 V, dE(r)/dT = -0.776 +/- 0.255 mV/K and E(h) = 3.893 +/- 0.0776 V. The difference between thermoneutral potential of Li/BCX and Li/SOCl2 cells is attributable to the difference in their electroactive components. C1 TEXAS A&M UNIV SYST,CTR ELECTROCHEM ENGN,DEPT CHEM ENGN,COLL STN,TX 77843. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RI Kalu, Egwu/C-6085-2013 NR 8 TC 3 Z9 4 U1 0 U2 3 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 10 SOUTH MAIN STREET, PENNINGTON, NJ 08534 SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD SEP PY 1992 VL 139 IS 9 BP 2378 EP 2381 DI 10.1149/1.2221234 PG 4 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA JL825 UT WOS:A1992JL82500011 ER PT J AU BUCHER, UJ MAST, F BISCHOF, N AF BUCHER, UJ MAST, F BISCHOF, N TI AN ANALYSIS OF OCULAR COUNTERROLLING IN RESPONSE TO BODY POSITIONS IN 3-DIMENSIONAL SPACE SO JOURNAL OF VESTIBULAR RESEARCH-EQUILIBRIUM & ORIENTATION LA English DT Article DE OCULAR COUNTERROLLING; 3D SPACE; PITCH; ROLL; TILT ID OTOLITH AB Four normal subjects underwent ocular counterrolling testing in a tiltable chair. Measurements were taken in 62 different body positions in steps of 30-degrees varied rolls and pitches. In each body position the eyes were recorded on video and their roll angle was determined automatically by computer analysis. The ocular counterrolling profile showed a periodic characteristic with maximal amplitude at roll tilts of 60-degrees. In this study we can clearly show that the eyes' rolling response is not systematically affected when lateral body tilts are combined with any tilts in the pitch direction. This undoubtedly implies that the ocular counterrolling was mainly stimulated by the subject's roll angle. As an empirical contribution, this study provides new data specially to be used in modelling and simulating the function of otolith organs. C1 NASA,AMES RES CTR,DIV HUMAN FACTORS RES,MOFFETT FIELD,CA 94035. UNIV ZURICH,DEPT PSYCHOL,BIOMATH SECT,CH-8006 ZURICH,SWITZERLAND. NR 31 TC 26 Z9 26 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0957-4271 J9 J VESTIBUL RES-EQUIL JI J. Vestib. Res.-Equilib. Orientat. PD FAL PY 1992 VL 2 IS 3 BP 213 EP 220 PG 8 WC Neurosciences; Otorhinolaryngology SC Neurosciences & Neurology; Otorhinolaryngology GA KF197 UT WOS:A1992KF19700003 PM 1342396 ER PT J AU SIRCAR, S CHATTOPADHYAY, K MAZUMDER, J AF SIRCAR, S CHATTOPADHYAY, K MAZUMDER, J TI NONEQUILIBRIUM SYNTHESIS OF NBAL3 AND NB-AL-V ALLOYS BY LASER CLADDING .1. MICROSTRUCTURE EVOLUTION SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article; Proceedings Paper CT SYMP ON REACTIONS SYNTHESIS OF MATERIALS, AT THE 1991 ANNUAL MEETING OF THE MINERALS, METALS AND MATERIALS SOC CY FEB 17-21, 1991 CL NEW ORLEANS, LA SP MINERALS MET & MAT SOC ID EXTENDED SOLID-SOLUTION; NI70AL20CR7HF3 ALLOYS; ELECTRON-DIFFRACTION; PLASTIC-DEFORMATION; HF AB NbAl3, like many ordered intermetallic compounds, appears to have great potential for application as high-temperature structural material because of the high melting point and stability in high-temperature oxidizing environments. However, the D0(22) (tI8) lattice structure shows limited ductility at room temperature. Addition of group IVB, VB, and VIB elements to Al3X (D0(22) type of compounds) as partial replacement of X is a method being applied by various researchers to promote ductility in these materials by activation of numerous dislocations and ordered twinning. In this study, V was added in different amounts to improve the ductility of NbAl3. However, this has an adverse effect on the oxidation response of the system, as is explained in Part II of this article. This article deals with the microstructure evolution, phase identification, and characterization of laser-clad (rapidly solidified) nominal NbAl3 and also studies the effect of V additions on the final microstructure in this system. Laser cladding of nominal NbAl3 produces two metastable unreported phases [body-centered tetragonal (bct) and base-centered orthorhombic phases]. Addition of V suppresses the primary phase (NbAl3) in the Nb-Al-V system. C1 UNIV ILLINOIS,DEPT MECH & IND ENGN,LASER AIDED MAT PROC LAB,URBANA,IL 61801. INDIAN INST SCI,DEPT MET,BANGALORE 560012,KARNATAKA,INDIA. RP SIRCAR, S (reprint author), NASA,WHITE SANDS TEST FACIL,LOCKHEED ENGN & SCI CO,JOHNSON SPACE CTR,LAS CRUCES,NM 88004, USA. NR 31 TC 12 Z9 13 U1 1 U2 5 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD SEP PY 1992 VL 23 IS 9 BP 2419 EP 2429 DI 10.1007/BF02658045 PG 11 WC Materials Science, Multidisciplinary SC Materials Science GA JM389 UT WOS:A1992JM38900012 ER PT J AU BRINDLEY, PK DRAPER, SL ELDRIDGE, JI NATHAL, MV ARNOLD, SM AF BRINDLEY, PK DRAPER, SL ELDRIDGE, JI NATHAL, MV ARNOLD, SM TI THE EFFECT OF TEMPERATURE ON THE DEFORMATION AND FRACTURE OF SIC/TI-24AL-11NB SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article; Proceedings Paper CT SYMP ON REACTIONS SYNTHESIS OF MATERIALS, AT THE 1991 ANNUAL MEETING OF THE MINERALS, METALS AND MATERIALS SOC CY FEB 17-21, 1991 CL NEW ORLEANS, LA SP MINERALS MET & MAT SOC ID TI-24AL-11NB; CREEP; ALLOY AB The tensile stress-strain behavior and failure mechanisms of Ti-24Al-11Nb and a SiC/Ti-24Al-11Nb composite with continuous SCS-6 fibers oriented parallel to the loading direction have been examined over a range of temperatures from 23-degrees-C to 815-degrees-C in air. Failure in Ti-24Al-11Nb occurred at strains of approximately 4 pct soon after crack initiation at low temperatures. Ductility increased with temperature up to a maximum of 20 pct elongation at 600-degrees-C, as surface-initiated cracks did not propagate readily at intermediate temperatures. At higher temperatures, the onset of grain boundary and interfacial void nucleation limited ductility. Composite failure appeared to be controlled by fiber fracture at all temperatures; for practical engineering purposes, composite failure occurred at 0.8 pct strain at all temperatures. At temperatures of 425-degrees-C and less, fiber fractures occurred at intervals along the lengths of the fibers and appeared to be cumulative, while at temperatures of 650-degrees-C and greater, fiber fractures were only observed locally to the fracture surfaces. The decreased radial residual stresses, interfacial strengths, and matrix properties at 650-degrees-C and 815-degrees-C allowed the composite to unload at 0.8 pct strain, due to fiber fractures, followed by a reloading in which fibers pulled out and the matrix failed, resulting in composite failure. The decreasing residual stresses with increasing temperature determined from an elastic-plastic concentric cylinder model were shown to affect the stress-strain response of the composite and were consistent with the measured decreasing interfacial shear stresses, the increased fiber pullout with temperature, and the circumferential debonding observed around the fibers at higher temperatures. RP BRINDLEY, PK (reprint author), NASA,LEWIS RES CTR,INTERMET BRANCH,CLEVELAND,OH 44135, USA. NR 35 TC 52 Z9 54 U1 0 U2 3 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD SEP PY 1992 VL 23 IS 9 BP 2527 EP 2540 DI 10.1007/BF02658056 PG 14 WC Materials Science, Multidisciplinary SC Materials Science GA JM389 UT WOS:A1992JM38900023 ER PT J AU DRAPER, SL BRINDLEY, PK NATHAL, MV AF DRAPER, SL BRINDLEY, PK NATHAL, MV TI EFFECT OF FIBER STRENGTH ON THE ROOM-TEMPERATURE TENSILE PROPERTIES OF SIC/TI-24AL-11NB SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article; Proceedings Paper CT SYMP ON REACTIONS SYNTHESIS OF MATERIALS, AT THE 1991 ANNUAL MEETING OF THE MINERALS, METALS AND MATERIALS SOC CY FEB 17-21, 1991 CL NEW ORLEANS, LA SP MINERALS MET & MAT SOC ID INTERFACIAL SHEAR-STRENGTH; METAL MATRIX COMPOSITES; CVD FILAMENTS; BORON AB To increase understanding of what controls SCS-6 SiC/Ti-24Al-11Nb (at. pct) composite strength, fibers of known strength were incorporated into composites and the effect of fiber strength variability on room temperature composite strength was investigated. Fiber was also etched out of a composite fabricated by the powder cloth technique, and the effect of the fabrication process on fiber strength was assessed. The strength of the composite was directly correlated with the strength of the as-received fiber. Fabrication by the powder cloth technique resulted in only a slight degradation of fiber strength. Examination of failed tensile specimens revealed periodic fiber cracks, and the failure mode was concluded to be cumulative. RP DRAPER, SL (reprint author), NASA,LEWIS RES CTR,INTERMET BRANCH,CLEVELAND,OH 44135, USA. NR 24 TC 49 Z9 49 U1 0 U2 1 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD SEP PY 1992 VL 23 IS 9 BP 2541 EP 2548 DI 10.1007/BF02658057 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA JM389 UT WOS:A1992JM38900024 ER PT J AU HAASCH, RT TEWARI, SK SIRCAR, S LOXTON, CM MAZUMDER, J AF HAASCH, RT TEWARI, SK SIRCAR, S LOXTON, CM MAZUMDER, J TI NONEQUILIBRIUM SYNTHESIS OF NBAL3 AND NB-AL-V ALLOYS BY LASER CLADDING .3. OXIDATION BEHAVIOR SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article; Proceedings Paper CT SYMP ON REACTIONS SYNTHESIS OF MATERIALS, AT THE 1991 ANNUAL MEETING OF THE MINERALS, METALS AND MATERIALS SOC CY FEB 17-21, 1991 CL NEW ORLEANS, LA SP MINERALS MET & MAT SOC AB In this study, the isothermal oxidation behavior of laser-clad NbAl3 has been investigated in the temperature range between 800-degrees-C and 1400-degrees-C in air. The effect on oxidation of vanadium microalloying, used to increase the ductility of the otherwise brittle NbAl3 and discussed in Part I,[1] has also been considered. Bulk and surface oxide chemistry has been investigated using X-ray diffraction and X-ray photoelectron spectroscopy (XPS), respectively. Oxidation kinetics have been determined from weight gain data. The XPS and X-ray diffraction data show that NbAl3 does not exclusively form a protective Al2O3 layer when oxidized in air. The oxidation products at 800-degrees-C are a mixture of Nb2O5 and Al2O3, while at 1200-degrees-C, a mixture of NbAlO4, Nb2O5, and Al2O3 is formed. At 1400-degrees-C, a mixture of NbAlO4, Al2O3, NbO2, NbO2.432, and Nb2O5 forms. Upon addition of vanadium, the oxidation rate is found to dramatically increase and may be related to the formation of (Nb, V)2O5 and VO2, which grows in favor of protective Al2O3. Consequently, although vanadium may be a good additive in terms of its potential for improving ductility in NbAl3, it is not in terms of its deleterious effects on oxidation. C1 NASA,WHITE SANDS TEST FACIL,LOCKHEED ENGN & SCI CO,JOHNSON SPACE CTR,LAS CRUCES,NM 88004. UNIV ILLINOIS,DEPT MECH & IND ENGN,URBANA,IL 61801. RP HAASCH, RT (reprint author), UNIV ILLINOIS,MAT RES LAB,SURFACE ANAL FACIL,URBANA,IL 61801, USA. NR 12 TC 7 Z9 9 U1 2 U2 2 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD SEP PY 1992 VL 23 IS 9 BP 2631 EP 2639 DI 10.1007/BF02658067 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA JM389 UT WOS:A1992JM38900034 ER PT J AU MITTLEFEHLDT, DW SEE, TH HORZ, F AF MITTLEFEHLDT, DW SEE, TH HORZ, F TI DISSEMINATION AND FRACTIONATION OF PROJECTILE MATERIALS IN THE IMPACT MELTS FROM WABAR CRATER, SAUDI-ARABIA SO METEORITICS LA English DT Article ID IRON-METEORITES; ELEMENT AB We have analyzed small, ballistically dispersed melt samples in the form of aerodynamically shaped spheres, dumbbells, teardrops, etc., from Wabar Crater, Saudi Arabia, and have compared these to our previous study of the more massive, black and white melt specimens. The smaller melt samples differ from the more massive melts in that they are petrographically and chemically more homogeneous, possess fewer, more diffuse schlieren and contain much less clastic detritus. These observations suggest higher peak temperatures for the smaller melt samples than for the massive black and white melts which represent Wabar's major melt-zone. Analyses of the Wabar and Nejed (paired with Wabar) meteorites permit detailed comparison of the unaltered projectile with impactor residues in the melts. Siderophile element concentrations indicate that the small glass beads commonly contain > 10% meteoritic component, compared to < 5% for the massive black and white melts. One glass bead was found to contain approximately 17% meteoritic component. Based on models for melt production during cratering, we deduce that more meteoritic material was mixed with the upper stratigraphic horizons of Wabar's melt zone than with the lower parts. Siderophile elements in all Wabar melt specimens are fractionated relative to the Wabar-Nejed meteorite and have Fe/Ni ratios up to approximately 1.8 times that of Wabar-Nejed for the most siderophile element-rich glasses. The abundance sequence of siderophiles in the melts relative to the projectile is Fe almost-equal-to Co > Ni almost-equal-to Ir almost-equal-to As much greater than Au. Although this sequence seems incompatible with simple vapor fractionation of either elements or oxides, we believe that a complex vapor fractionation process most likely produced the observed siderophile element abundances. Our sample suite should be representative of all materials found in and around the Wabar structure, and we conclude that substantial quantities of the projectile were lost to the atmosphere, most likely as vapor. No fractionation of lithophile elements is observed in the glasses relative to the target rocks. Although fractionation of the impactor must have occurred prior to intimate mixing of projectile and target, details of the actual fractionation mechanism(s) remain poorly understood. The results of this study indicate that caution is necessary when attempting to define impactor types and masses from compositional data for impact melts from other craters. C1 NASA,LYNDON B JOHNSON SPACE CTR,DIV SOLAR SYST EXPLORAT,HOUSTON,TX 77058. RP MITTLEFEHLDT, DW (reprint author), LOCKHEED ESC,C23,2400 NASA RD 1,HOUSTON,TX 77058, USA. NR 33 TC 54 Z9 54 U1 2 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1992 VL 27 IS 4 BP 361 EP 370 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU056 UT WOS:A1992JU05600006 ER PT J AU GARRISON, DH BOGARD, DD ALBRECHT, AA VOGT, S HERZOG, GF KLEIN, J FINK, D DEZFOULYARJOMANDY, B MIDDLETON, R AF GARRISON, DH BOGARD, DD ALBRECHT, AA VOGT, S HERZOG, GF KLEIN, J FINK, D DEZFOULYARJOMANDY, B MIDDLETON, R TI COSMOGENIC NUCLIDES IN CORE SAMPLES OF THE CHICO L6-CHONDRITE - EVIDENCE FOR IRRADIATION UNDER HIGH SHIELDING SO METEORITICS LA English DT Article ID RAY EXPOSURE AGES; CHONDRITES; METEORITE; COMPILATION; NE-21 AB Core samples were obtained from various locations of the approximately 105-kg Chico, NM, L6 chondrite in order to study the effects of large shielding on the production rates of cosmic-ray-produced nuclides. Relations between measured abundances of cosmogenic nuclides (Be-10, Al-26, and stable isotopes of He, Ne, and Ar) and the cosmogenic Ne-22/Ne-21 ratio were determined and compared with recent model predictions of production rates. The measured Ne-22/Ne-21 ratios (1.06-1.08) and significant variations observed in concentrations of cosmogenic Ne-21 and He-3 suggest an approximately 40-cm shielding gradient across Chico and irradiation within a large object (> 100-cm radius). Noble gas data indicate that Chico experienced greater shielding than chondrites Knyahinya or Keyes and similar to Jilin. Values of Be-10 (average = 20.7 dpm/kg) and Al-26 (average = 71.1 dpm/kg) are nearly constant, however, and show no correlation with either Ne-22/Ne-21 or Ne-21. Activities of Be-10 and Al-26 suggest irradiation in a smaller object (approximately 40-80 cm radius). The Al-26 activity and the Al-26/Be-10 ratio (average value = 3.42) are both significantly larger than values for most other chondrites. These results could indicate a two-stage irradiation with t1 approximately 104 Ma and t2 approximately 4 Ma and a second-stage body the size of Knyahinya. The single stage, Be-10/Ne-21 exposure age for Chico is 65 Ma. The Ne-22/Ne-21 ratio apparently becomes insensitive to shielding for objects the size of Chico. No substantial evidence exists for chondrites with Ne-22/Ne-21 ratios significantly less than approximately 1.055. C1 RUTGERS STATE UNIV,DEPT CHEM,NEW BRUNSWICK,NJ 08903. UNIV PENN,DEPT PHYS,PHILADELPHIA,PA 19104. RP GARRISON, DH (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,LESC,HOUSTON,TX 77058, USA. RI fink, David/A-9518-2012 NR 36 TC 23 Z9 23 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1992 VL 27 IS 4 BP 371 EP 381 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU056 UT WOS:A1992JU05600007 ER PT J AU CINTALA, MJ HORZ, F AF CINTALA, MJ HORZ, F TI AN EXPERIMENTAL EVALUATION OF MINERAL-SPECIFIC COMMINUTION SO METEORITICS LA English DT Article ID GRAIN-SIZE FRACTIONS; LUNAR REGOLITH; GEOCHEMISTRY; PETROLOGY; STRATIGRAPHY; EVOLUTION; CHEMISTRY; SOIL AB Early "regolith-evolution" experiments using fragmental, polycrystalline gabbro targets displayed mineral-specific comminution trends, with feldspar being significantly fractionated into the finest grain sizes. Since planetary regoliths are similar mixtures of lithic and monomineralic detritus, the comminution of monomineralic grains is important in understanding the evolution of such regoliths. Particulate targets of monomineralic feldspar, olivine, pyroxene, and quartz therefore were subjected to at least 25 impacts each to complement the previous gabbro-based investigations. Stainless-steel projectiles 3.18 mm in diameter were launched at the targets at nominal velocities of 1.4 km s-1, depositing an average of about 2.6 x 10(6) ergs per g of target per impact. The quartz and feldspar comminuted most readily, while olivine and pyroxene were the most resistant. In addition, the feldspar and quartz were virtually indistinguishable in terms of any measure of comminution used here. The behavior of the olivine differed somewhat from that of the pyroxene, but the variation between these two minerals was much less than the difference between them and the tectosilicates. The apparent energy required to create new surfaces through comminution was about a factor of two higher for the mafic minerals. Densities of pre-existing cracks and other crystal defects depend on sample preparation techniques, among other things, and appear to play a notable role in the early evolution of these "regoliths." It is probable that the history of a particular regolith's parent rocks will exert a comparable influence on the early stages of evolution of a planetary regolith. The trends for the individual targets in these monomineralic series duplicated those exhibited by the gabbro charges, leading to the general conclusion that mineral-specific comminution will occur during repetitive impact of planetary surfaces, whether they comprise freshly excavated, large blocks, or highly comminuted, clastic fines containing substantial fractions of monomineralic debris. This mineral-specific behavior will cause small grain sizes in planetary regoliths to be substantially fractionated relative to coarse regolith components, and especially relative to their source rocks. RP CINTALA, MJ (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV SOLAR SYST EXPLORAT,CODE SN4,HOUSTON,TX 77058, USA. NR 28 TC 20 Z9 20 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1992 VL 27 IS 4 BP 395 EP 403 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU056 UT WOS:A1992JU05600010 ER PT J AU ZOLENSKY, ME RENDELL, HM WILSON, I WELLS, GL AF ZOLENSKY, ME RENDELL, HM WILSON, I WELLS, GL TI THE AGE OF THE METEORITE RECOVERY SURFACES OF ROOSEVELT COUNTY, NEW-MEXICO, USA SO METEORITICS LA English DT Note ID EARTHS SURFACE; FALLS AB We have obtained minimum age estimates for the sand units underlying the two largest meteorite deflation surfaces in Roosevelt County, New Mexico, USA, using thermoluminescence dating techniques. The dates obtained ranged from 53.5 (+/-5.4) to 95.2 (+/-9.5) ka, and must be considered lower limits for the terrestrial ages of the meteorites found within these specific deflation surfaces. These ages greatly exceed previous measurements from adjacent meteorite-producing deflation basins. We find that Roosevelt County meteorites are probably terrestrial contemporaries of the meteorites found at most accumulation zones in Antarctica. The apparent high meteorite accumulation rate reported for Roosevelt County by Zolensky et al. (1990) is incorrect, as it used an age of 16 ka for all Roosevelt County recovery surfaces. We conclude that the extreme variability of terrestrial ages of the Roosevelt County deflation surfaces effectively precludes their use for calculations of the meteorite accumulation rate at the Earth's surface. C1 UNIV SUSSEX,GEOG LAB,BRIGHTON BN1 9QN,ENGLAND. RP ZOLENSKY, ME (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH,HOUSTON,TX 77058, USA. NR 11 TC 13 Z9 13 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1992 VL 27 IS 4 BP 460 EP 462 PG 3 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU056 UT WOS:A1992JU05600017 ER PT J AU GOODWIN, TJ PELLIS, NR RISIN, D SPAULDING, GF AF GOODWIN, TJ PELLIS, NR RISIN, D SPAULDING, GF TI INHIBITION OF NORMAL HUMAN PERIPHERAL-BLOOD LYMPHOCYTE LOCOMOTION THROUGH COLLAGEN MATRIX IN SIMULATED MICROGRAVITY SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 KRUG LIFE SCI,HOUSTON,TX 77058. UNIV TEXAS,MD ANDERSON CANC CTR,HOUSTON,TX 77030. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA PUBL OFFICE, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD SEP PY 1992 VL 3 SU S BP A361 EP A361 PG 1 WC Cell Biology SC Cell Biology GA JR255 UT WOS:A1992JR25502100 ER PT J AU JESSUP, JM BROWN, K ISHII, S FORD, R GOODWIN, TJ SPAULDING, G AF JESSUP, JM BROWN, K ISHII, S FORD, R GOODWIN, TJ SPAULDING, G TI SIMULATED MICROGRAVITY DOES NOT ALTER EPITHELIAL-CELL ADHESION TO MATRIX AND OTHER MOLECULES SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 NEW ENGLAND DEACONESS HOSP,BOSTON,MA 02215. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA PUBL OFFICE, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD SEP PY 1992 VL 3 SU S BP A71 EP A71 PG 1 WC Cell Biology SC Cell Biology GA JR255 UT WOS:A1992JR25500413 ER PT J AU PREWETT, TL GOODWIN, TJ SPAULDING, GF BECKER, JL AF PREWETT, TL GOODWIN, TJ SPAULDING, GF BECKER, JL TI MORPHOLOGICAL AND IMMUNOHISTOCHEMICAL ANALYSIS OF LN1 OVARIAN TUMOR-CELL LINE GROWN IN ROTATING-WALL VESSELS SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 KRUG LIFE SCI,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV S FLORIDA,TAMPA,FL 33606. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA PUBL OFFICE, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD SEP PY 1992 VL 3 SU S BP A23 EP A23 PG 1 WC Cell Biology SC Cell Biology GA JR255 UT WOS:A1992JR25500130 ER PT J AU MANOBIANCO, J UCCELINI, LW BRILL, KF KUO, YH AF MANOBIANCO, J UCCELINI, LW BRILL, KF KUO, YH TI THE IMPACT OF DYNAMIC DATA ASSIMILATION ON THE NUMERICAL SIMULATIONS OF THE QE-II CYCLONE AND AN ANALYSIS OF THE JET STREAK INFLUENCING THE PRECYCLOGENETIC ENVIRONMENT SO MONTHLY WEATHER REVIEW LA English DT Article ID 4-DIMENSIONAL DATA ASSIMILATION; CUMULUS CONVECTION; STORM; CYCLOGENESIS; INTENSIFICATION; INITIALIZATION; EVOLUTION; MODELS; IOP-1 AB The rapid intensification of a surface cyclone that battered the Queen Elizabeth II (QE II) ocean liner in the western Atlantic Ocean during September 1978 has been the focus of several observational and model-based case studies. The storm is considered a classic example of a cyclone that undergoes explosive deepening, marked by a 60-hPa decrease of the central mean sea level pressure (MSLP) in 24 h. The present study uses a regional-scale numerical model in conjunction with dynamic data assimilation via Newtonian relaxation (or "nudging") to provide initial conditions for subsequent simulations of the QE II cyclone. The objectives of this paper are 1 ) to show that the simulations initialized from the results of 12-h precyclogenetic data-assimilation cycles (with and without bogus data) are superior to those initialized statically from the same data and 2) to resolve the evolution of the upper-level trough-jet system in the 24-h period from 0000 UTC 9 September-0000 UTC 10 September using the dynamically consistent four-dimensional (4D) datasets generated by the model. The 4D model-generated datasets provide the spatial and temporal data resolution not afforded in the observational studies to document the structure and evolution of the dynamical forcing associated with the QE H cyclone. However, the temporal continuity of the cyclone's development, especially the evolution of the upper-level trough-jet system and the associated indirect circulations in the exit region of the upper-tropospheric jet streak, is interrupted at the end of the nudging cycle. This problem poses a limitation for using the 4D datasets for diagnostic studies of the QE II cyclone in the precyclogenetic period during the data-assimilation cycle. Dynamic data assimilation and the inclusion of supplementary data both have a large positive impact on the simulated position and intensity of the QE II cyclone from 1200 UTC 9 September to 0000 UTC 10 September during the initial phase of rapid cyclone development. These runs capture the developing cyclone and associated rate of MSLP falls at 1200 UTC 9 September, whereas the runs based on static initialization delay the deepening six to nine hours into the model simulation. The diagnostic analyses based on these simulations show that the initial development of the QE II storm between 0000 UTC 9 September and 0000 UTC 10 September was embedded within an indirect circulation of an intense 300-hPa jet streak, was related to baroclinic processes that extended throughout a deep portion of the troposphere and was associated with a classic two-layer mass-divergence profile expected for an extratropical cyclone. The runs initialized from data-assimilation cycles, including the bogus data, still underestimate the MSLP of the QE II cyclone by 30% at 24 h into the simulations (1200 UTC 10 September). These results provide further supporting evidence that increasing the horizontal model resolution and improving the subgrid-scale physical parameterizations (especially the precipitation schemes) may be required to simulate the most rapid development phase of the QE II cyclone. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. NOAA,NATL WEATHER SERV,NATL METEROL CTR,CAMP SPRINGS,MD. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. RP MANOBIANCO, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,RES & DATA SYST,CODE 912,GREENBELT,MD 20771, USA. NR 24 TC 3 Z9 3 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD SEP PY 1992 VL 120 IS 9 BP 1973 EP 1996 DI 10.1175/1520-0493(1992)120<1973:TIODDA>2.0.CO;2 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL580 UT WOS:A1992JL58000010 ER PT J AU ATLAS, D BELL, TL AF ATLAS, D BELL, TL TI THE RELATION OF RADAR TO CLOUD AREA - TIME INTEGRALS AND IMPLICATIONS FOR RAIN MEASUREMENTS FROM SPACE SO MONTHLY WEATHER REVIEW LA English DT Article ID CONVECTIVE RAINFALL; TROPICAL RAINFALL; SATELLITE; GATE; IMAGERY AB In this work we determine the relationships between satellite-based and radar-measured area-time integrals (ATI) for convective storms and show how both depend upon the climatological conditional mean rain rate R(c) and the ratio of the measured cloud (or radar echo) area to the actual rain area of the storms. Arkin's GOES precipitation index (GPI) = GF(c)T (mm) where F(c) is the fraction of a 2.5-degrees box in GATE [GARP (Global Atmospheric Research Program) Atlantic Tropical Experiment] having clouds with infrared (IR) brightness temperatures less than 235 K, G = 3 mm h -1, and T is cloud duration. However, we show that G is the ratio of R(c) to [A(c)]/[A(r)] where A(c) and A(r) denote cloud and rain area, respectively. We have demonstrated that Arkin's GPI reaches a stable asymptotic value for boxes of 2.5-degrees in size because they include a sufficient number of storm cells to ensure that 1 ) the sample R(c), and thus the probability density function (PDF) of R, are representative of those in the climatological population; and 2) the ratio of the averages [A(c)]/A(r)] is similarly representative of the typical storm structure for the climatic regime. As the space-time sampling domain decreases, the correlation of GPI with cloud fraction decreases because these conditions are not met. Also, as the spatial sampling domain decreases, G decreases and the ratio [A(c)]/[A(r)] increases because the smaller areas tend to have a larger fraction of rain-free cloud. Since [A(c)]/[A(r)] must vary with storm type and climatic regime, the asymptotic (large area) GPI developed for GATE is unlikely to be valid for other regions. Smith et al. have also found a satellite cloud ATI for individual convective storms in North Dakota using a threshold IR brightness temperature of 250 K. In this case, we find that the ratio of the cloud to radar ATIs increases with the total volumetric rainfall, presumably because the more intense storms are associated with stronger updrafts and upper-level divergence, thus causing the cloud areas to exceed the rain areas by progressively larger amounts. Nevertheless, if the relationship between cloud and radar ATI is a stable one for a sufficient sample domain in each climatic regime, as is to be expected, then the cloud ATI becomes as powerful an estimator of convective rain as is the radar ATI (Rosenfeld et al. and others). One of its most valuable applications would be in conjunction with a satellite radar and/or radiometer as proposed for the Tropical Rainfall Measuring Mission (TRMM). TRMM could then serve as a global calibrating device to eliminate systematic biases. The increased sampling rate with the geosynchronous ATI would greatly improve the accuracy of the rainfall estimates, resulting in rms errors of 15%-20% of the mean in 2.5-degrees boxes and 12 h, as compared with the 10% error for monthly averages over 5-degrees boxes anticipated for TRMM. Such estimates would be useful for regional- and global-scale monitoring and forecasting. RP ATLAS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. RI Bell, Thomas/G-5425-2012 NR 35 TC 23 Z9 23 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD SEP PY 1992 VL 120 IS 9 BP 1997 EP 2008 DI 10.1175/1520-0493(1992)120<1997:TRORTC>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL580 UT WOS:A1992JL58000011 ER PT J AU LANDIS, GA AF LANDIS, GA TI NEW APPROACHES FOR A SOLAR-PUMPED GAAS-LASER SO OPTICS COMMUNICATIONS LA English DT Article AB Approaches are discussed for a direct solar-pumped semiconductor laser. Efficiencies of 35% should be achievable. The intensity threshold can be decreased by using a wider bandgap material for the absorber material than for the lasing material and by the use of light-trapping structures. The calculated minimum threshold is about 50 times the solar concentration (without light-trapping) or about one solar concentration (with light-trapping). RP LANDIS, GA (reprint author), NASA,LEWIS RES CTR 302-1,SVERDRUG TECHNOL,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 8 TC 6 Z9 6 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0030-4018 J9 OPT COMMUN JI Opt. Commun. PD SEP 1 PY 1992 VL 92 IS 4-6 BP 261 EP 265 DI 10.1016/0030-4018(92)90633-3 PG 5 WC Optics SC Optics GA JK610 UT WOS:A1992JK61000019 ER PT J AU SPIRKOVSKA, L REID, MB AF SPIRKOVSKA, L REID, MB TI ROBUST POSITION, SCALE, AND ROTATION INVARIANT OBJECT RECOGNITION USING HIGHER-ORDER NEURAL NETWORKS SO PATTERN RECOGNITION LA English DT Article DE NEURAL NETWORKS; HIGHER-ORDER; WHITE NOISE; GAUSSIAN NOISE; OCCLUSION; OBJECT RECOGNITION; INVARIANT CLASSIFICATION; COARSE-CODING AB For object recognition invariant to changes in the object's position, size, and in-plane rotation, higher-order neural networks (HONNs) have numerous advantages over other neural network approaches. Because distortion invariance can be built into the architecture of the network, HONNs need to be trained on just one view of each object, not numerous distorted views, reducing the training time significantly. Further, 100% accuracy can be guaranteed for noise-free test images characterized by the built-in distortions. Specifically, a third-order neural network trained on just one view of an SR-71 aircraft and a U-2 aircraft in a 127 x 127 pixel input field successfully recognized all views of both aircraft larger than 70% of the original size, regardless of orientation or position of the test image. Training required just six passes. In contrast, other neural network approaches require thousands of passes through a training set consisting of a much larger number of training images and typically achieve only 80-90% accuracy on novel views of the objects. The above results assume a noise-free environment. The performance of HONNs is explored with non-ideal test images characterized by white Gaussian noise or partial occlusion. With white noise added to images with an ideal separation of background vs. foreground gray levels, it is shown that HONNs achieve 100% recognition accuracy for the test set for a standard deviation up to approximately 10% of the maximum gray value and continue to show good performance (defined as better than 75% accuracy) up to a standard deviation of approximately 14%. HONNs are also robust with respect to partial occlusion. For the test set of training images with very similar profiles, HONNs achieve 100% recognition accuracy for one occlusion of approximately 13% of the input field size and four occlusions of approximately 70% of the input field size. They show good performance for one occlusion of approximately 23% of the input field size or four occlusions of approximately 15% of the input field size each. For training images with very different profiles, HONNs achieve 100% recognition accuracy for the test set for up to four occlusions of approximately 2% of the input field size and continue to show good performance for up to four occlusions of approximately 23% of the input field size each. RP SPIRKOVSKA, L (reprint author), NASA,AMES RES CTR,M-S 269-3,MOFFETT FIELD,CA 94035, USA. NR 10 TC 30 Z9 31 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0031-3203 J9 PATTERN RECOGN JI Pattern Recognit. PD SEP PY 1992 VL 25 IS 9 BP 975 EP 985 DI 10.1016/0031-3203(92)90062-N PG 11 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA JW175 UT WOS:A1992JW17500008 ER PT J AU SCHMID, PJ HENNINGSON, DS AF SCHMID, PJ HENNINGSON, DS TI A NEW MECHANISM FOR RAPID TRANSITION INVOLVING A PAIR OF OBLIQUE WAVES SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article AB A pair of small but finite-amplitude oblique waves were used as initial condition in numerical simulations of transition to turbulent flow. A rapid energy growth to a transition peak occurred. Although this transition scenario is triggered by a nonlinear interaction, the dominant mechanism yielding substantial disturbance amplitudes was found to be linear. A number of simulations were made that showed that the overall features of this transition scenario remains the same for a range of parameter values. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP SCHMID, PJ (reprint author), MIT,DEPT MATH,CAMBRIDGE,MA 02139, USA. NR 11 TC 64 Z9 64 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD SEP PY 1992 VL 4 IS 9 BP 1986 EP 1989 DI 10.1063/1.858367 PG 4 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JL123 UT WOS:A1992JL12300011 ER PT J AU POWERS, JM GONTHIER, KA AF POWERS, JM GONTHIER, KA TI REACTION ZONE STRUCTURE FOR STRONG, WEAK OVERDRIVEN, AND WEAK UNDERDRIVEN OBLIQUE DETONATIONS SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID VORTICITY; WAVES AB A simple dynamic systems analysis is used to give examples of strong, weak overdriven, and weak underdriven oblique detonations. Steady oblique detonations consisting of a straight lead shock attached to a solid wedge followed by a resolved reaction zone structure are admitted as solutions to the reactive Euler equations. This is demonstrated for a fluid that is taken to be an inviscid, calorically perfect ideal gas that undergoes a two-step irreversible reaction with the first step exothermic and the second step endothermic. This model admits solutions for a continuum of shock wave angles for two classes of solutions identified by a Rankine-Hugoniot analysis: strong and weak overdriven waves. The other class, weak underdriven, is admitted for eigenvalue shock-wave angles. Chapman-Jouguet waves, however, are not admitted. These results contrast those for a corresponding one-step model that, for detonations with a straight lead shock, only admits strong, weak overdriven, and Chapman-Jouguet solutions. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP POWERS, JM (reprint author), UNIV NOTRE DAME,DEPT AEROSP & MECH ENGN,NOTRE DAME,IN 46556, USA. RI Powers, Joseph/A-7086-2013 OI Powers, Joseph/0000-0001-8694-8369 NR 14 TC 11 Z9 11 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD SEP PY 1992 VL 4 IS 9 BP 2082 EP 2089 DI 10.1063/1.858378 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JL123 UT WOS:A1992JL12300022 ER PT J AU LANDIS, GA AF LANDIS, GA TI ELF-FIELD HEALTH-EFFECTS - BIOLOGICAL, OR ILLOGICAL SO PHYSICS TODAY LA English DT Letter RP LANDIS, GA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD SEP PY 1992 VL 45 IS 9 BP 13 EP 13 PG 1 WC Physics, Multidisciplinary SC Physics GA JM395 UT WOS:A1992JM39500003 ER PT J AU SMITH, MF LOCKWOOD, M COWLEY, SWH AF SMITH, MF LOCKWOOD, M COWLEY, SWH TI THE STATISTICAL CUSP - A FLUX-TRANSFER EVENT MODEL SO PLANETARY AND SPACE SCIENCE LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; DAYSIDE AURORAL ACTIVITY; BOUNDARY-LAYER; SOLAR-WIND; PLASMA CONVECTION; MAGNETOPAUSE; RECONNECTION; ION; MAGNETOSHEATH; IONOSPHERE AB Traditionally, the cusp has been described in terms of a time-stationary feature of the magnetosphere which allows access of magnetosheath-like plasma to low altitudes. Statistical surveys of data from low-altitude spacecraft have shown the average characteristics and position of the cusp. Recently, however, it has been suggested that the ionospheric footprint of flux transfer events (FTEs) may be identified as variations of the "cusp" on timescales of a few minutes. In this model, the cusp can vary in form between a steady-state feature in one limit and a series of discrete ionospheric FTE signatures in the other limit. If this time-dependent cusp scenario is correct, then the signatures of the transient reconnection events must be able, on average, to reproduce the statistical cusp occurrence previously determined from the satellite observations. In this paper, we predict the precipitation signatures which are associated with transient magnetopause reconnection, following recent observations of the dependence of dayside ionospheric convection on the orientation of the IMF. We then employ a simple model of the longitudinal motion of FTE signatures to show how such events can easily reproduce the local time distribution of cusp occurrence probabilities, as observed by low-altitude satellites. This is true even in the limit where the cusp is a series of discrete events. Furthermore, we investigate the existence of double cusp patches predicted by the simple model and show how these events may be identified in the data. C1 RUTHERFORD APPLETON LAB,DIDCOT OX11 0QX,OXON,ENGLAND. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. RP SMITH, MF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Lockwood, Mike/G-1030-2011 OI Lockwood, Mike/0000-0002-7397-2172 NR 63 TC 43 Z9 43 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD SEP PY 1992 VL 40 IS 9 BP 1251 EP 1268 DI 10.1016/0032-0633(92)90082-Y PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR072 UT WOS:A1992JR07200009 ER PT J AU CHENG, SZD WU, XX ZHANG, AQ MEADOR, MA AF CHENG, SZD WU, XX ZHANG, AQ MEADOR, MA TI THERMAL-PROPERTIES, PHASE-TRANSITIONS, AND MORPHOLOGY OF A CONJUGATED POLYMER SO POLYMER ENGINEERING AND SCIENCE LA English DT Article ID PARA-AROMATIC POLYMERS; RIGID-ROD POLYMERS; MAIN CHAIN; CRYSTALLIZATION; UNITS AB A highly conjugated polymer was synthesized from alpha,alpha'-dibromo-p-xylene, 1,4-bis(2-hydroxy-benzoyl)benzene, and benzyl bromide via a modified Williamson ether synthesis under phase transfer conditions. Based on thermal analysis, polarized light microscopy, electron diffraction, and wide angle X-ray diffraction experiments, the heat capacities in the solid and liquid states have been determined. The glass transition temperature is at 358 K with a heat capacity increase of 164 J/(K mol). Two different ordered crystal forms with different crystal unit cells were observed. The more ordered crystal shows a low transition temperature and the less ordered one a high transition temperature. This is mainly due to the effect of entropy change. These crystals exhibit various crystal morphologies with different birefringences. Transition kinetics are expressed by an Avrami equation. Two crystals show different Avrami exponents with crystallization temperature, which correspond to the morphological change. Competition between crystal growths is also discussed. C1 NASA,LEWIS RES CTR,DIV MAT,POLYMERS BRANCH,CLEVELAND,OH 44135. RP CHENG, SZD (reprint author), UNIV AKRON,COLL POLYMER SCI & POLYMER ENGN,INST & DEPT POLYMER SCI,AKRON,OH 44325, USA. NR 21 TC 0 Z9 0 U1 0 U2 1 PU SOC PLASTICS ENG INC PI BROOKFIELD CENTER PA 14 FAIRFIELD DR, BROOKFIELD CENTER, CT 06804-0403 SN 0032-3888 J9 POLYM ENG SCI JI Polym. Eng. Sci. PD SEP PY 1992 VL 32 IS 17 BP 1325 EP 1332 DI 10.1002/pen.760321721 PG 8 WC Engineering, Chemical; Polymer Science SC Engineering; Polymer Science GA JN205 UT WOS:A1992JN20500020 ER PT J AU NGHIEM, SV YUEH, SH KWOK, R LI, FK AF NGHIEM, SV YUEH, SH KWOK, R LI, FK TI SYMMETRY PROPERTIES IN POLARIMETRIC REMOTE-SENSING SO RADIO SCIENCE LA English DT Article ID RADAR IMAGES; CALIBRATION AB This paper presents the relations among polarimetric backscattering coefficients from the viewpoint of symmetry groups. Symmetry of geophysical media encountered in remote sensing due to reflection, rotation, azimuthal, and centrical symmetry groups is considered for both reciprocal and nonreciprocal cases. On the basis of the invariance under symmetry transformations in the linear polarization basis, the scattering coefficients are related by a set of equations which restrict the number of independent parameters in the polarimetric covariance matrix. The properties derived under these transformations are general and apply to all scattering mechanisms in a given symmetrical configuration. The scattering coefficients calculated from theoretical models for layer random media and rough surfaces are shown to obey the derived symmetry relations. Use of symmetry properties in remote sensing of structural and environmental responses of scattering media is discussed. As a practical application, the results from this paper provide new methods for the external calibration of polarimetric radars without the deployment of man-made calibration targets. RP NGHIEM, SV (reprint author), JET PROP LAB,MAIL STOP 300-235,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 15 TC 137 Z9 140 U1 0 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD SEP-OCT PY 1992 VL 27 IS 5 BP 693 EP 711 DI 10.1029/92RS01230 PG 19 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA JR536 UT WOS:A1992JR53600013 ER PT J AU YOST, WT CANTRELL, JH AF YOST, WT CANTRELL, JH TI ABSOLUTE ULTRASONIC DISPLACEMENT AMPLITUDE MEASUREMENTS WITH A SUBMERSIBLE ELECTROSTATIC ACOUSTIC TRANSDUCER SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB An experimental technique for absolute measurement of ultrasonic wave particle displacement amplitudes in liquids is reported. The technique is capable of measurements over a frequency range of two decades with a sensitivity less than one angstrom. The technique utilizes a previously reported submersible electrostatic acoustic transducer (ESAT) [Rev. Sci. Instrum. 50, 31 (1979)] featuring a conductive membrane stretched over a recessed electrode. An uncertainty analysis shows that the displacement amplitude of an ultrasonic plane wave incident on the ESAT can be experimentally determined to better than 2.3%-4%, depending on frequency, in the frequency range of 0.5-15 MHz. Membranes with lower and more uniform areal densities can improve the accuracy and extend the operation to higher frequencies. RP YOST, WT (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 231,HAMPTON,VA 23665, USA. NR 5 TC 19 Z9 19 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD SEP PY 1992 VL 63 IS 9 BP 4182 EP 4188 DI 10.1063/1.1143231 PG 7 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JL575 UT WOS:A1992JL57500025 ER PT J AU GILBERT, JR SCHREIBER, R AF GILBERT, JR SCHREIBER, R TI HIGHLY PARALLEL SPARSE CHOLESKY FACTORIZATION SO SIAM JOURNAL ON SCIENTIFIC AND STATISTICAL COMPUTING LA English DT Article DE SPARSE MATRIX ALGORITHMS; CHOLESKY FACTORIZATION; SUPERNODAL FACTORIZATION; MULTIFRONTAL FACTORIZATION; SYSTEMS OF LINEAR EQUATIONS; PARALLEL COMPUTING; DATA PARALLEL ALGORITHMS; CHORDAL GRAPHS; CLIQUE TREES; CONNECTION MACHINE; PERFORMANCE ANALYSIS ID ELIMINATION; SYSTEMS; TREES AB This paper develops and compares several fine-grained parallel algorithms to compute the Cholesky factorization of a sparse matrix. The experimental implementations are on the Connection Machine, a distributed-memory SIMD machine whose programming model conceptually supplies one processor per data element. In contrast to special-purpose algorithms in which the matrix structure conforms to the connection structure of the machine, this paper focuses on matrices with arbitrary sparsity structure. The most promising alternative is a supernodal, multifrontal algorithm whose inner loop performs several dense factorizations simultaneously on a two-dimensional grid of processors. The key subroutine is a fine-grained parallel, dense-factorization algorithm. The sparse code attains execution rates comparable to those of the dense subroutine. Although at present architectural limitations prevent the dense factorization from realizing its potential efficiency, it is concluded that a regular data parallel architecture can be used efficiently to solve arbitrarily structured sparse problems. A performance model is also presented and used to analyze these algorithms. Asymptotic analysis combined with experimental measurement of parameters is accurate enough to be useful in choosing among alternative algorithms for a complicated problem. C1 NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035. RP GILBERT, JR (reprint author), XEROX CORP,PALO ALTO RES CTR,333 COYOTE HILL RD,PALO ALTO,CA 94304, USA. NR 35 TC 21 Z9 21 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 0196-5204 J9 SIAM J SCI STAT COMP PD SEP PY 1992 VL 13 IS 5 BP 1151 EP 1172 DI 10.1137/0913067 PG 22 WC Mathematics, Applied SC Mathematics GA JK049 UT WOS:A1992JK04900007 ER PT J AU CHACKERIAN, C VAIDA, V AF CHACKERIAN, C VAIDA, V TI ATMOSPHERIC AND PLANETARY SPECTROSCOPY - PREFACE SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Editorial Material C1 UNIV COLORADO,DEPT CHEM,BOULDER,CO 80309. RP CHACKERIAN, C (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Vaida, Veronica/N-6069-2014 OI Vaida, Veronica/0000-0001-5863-8056 NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0584-8539 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD SEP PY 1992 VL 48 IS 9 BP 1201 EP 1202 DI 10.1016/0584-8539(92)80256-V PG 2 WC Spectroscopy SC Spectroscopy GA JP756 UT WOS:A1992JP75600001 ER PT J AU WEBER, M BLASS, WE HALSEY, GW HILLMAN, JJ MAGUIRE, WC AF WEBER, M BLASS, WE HALSEY, GW HILLMAN, JJ MAGUIRE, WC TI L-RESONANCE EFFECTS IN THE NU(5),2-NU(5)[-NU(5), AND NU(4)+NU(5)[-NU(4) BANDS OF C2H2 AND (CCH2)-C-13-C-12 NEAR 13.7-MU-M SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article ID MOLECULAR-CONSTANTS; LINEAR-MOLECULES; ACETYLENE; SPECTRA; REGION; ETHANE; IDENTIFICATION; ATMOSPHERE; NEPTUNE; SYSTEM AB An extension to the previous LSCD (lower state combination difference) determination of molecular parameters involving acetylene's nu5 fundamental and the strongest one quantum hotbands, 2nu5 <-- nu5 and nu4 + nu5 <-- nu4 [J. Molec. Spectrosc. 146, 389 (1991)] has been made. A novel iterative numerical diagonalization procedure was employed to fit the vibrational states involved in the seven one quantum hotbands. This method utilizes the Hellmann-Feynman theorem to calculate first derivatives and singular value decomposition (SVD) in its least-square procedure and permits the simultaneous evaluation of the effective dipole moment responsibie for the l-type resonance effect upon IR intensities. A set of molecular parameters describing the rotation-vibration levels of the ground state, nu5, nu4, 2nu5 and nu4 + nu5 for the major isotope and for (CCH2)-C-13-C-12 are reported based upon FT-spectrometric data taken at the McMath Solar Telescope Observatory. The improved spectroscopic parameters retrieved from this investigation will serve as a database for modelling abundances of acetylene in various astrophysical sources. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP WEBER, M (reprint author), UNIV TENNESSEE,DEPT PHYS,KNOXVILLE,TN 37996, USA. RI Blass, William/A-2792-2008; Weber, Mark/F-1409-2011 OI Weber, Mark/0000-0001-8217-5450 NR 41 TC 10 Z9 10 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0584-8539 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD SEP PY 1992 VL 48 IS 9 BP 1203 EP 1226 DI 10.1016/0584-8539(92)80257-W PG 24 WC Spectroscopy SC Spectroscopy GA JP756 UT WOS:A1992JP75600002 ER PT J AU LOEWENSTEIN, M WILSON, HW AF LOEWENSTEIN, M WILSON, HW TI LINEWIDTH TEMPERATURE-DEPENDENCE OF SELECTED R-BRANCH TRANSITIONS IN THE NU(3) FUNDAMENTAL OF (N2O)-N-4-O-16 BETWEEN 135-K AND 295-K SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article ID LASER ABSORPTION SPECTROMETER; ANTARCTIC OZONE EXPERIMENT; NITROUS-OXIDE; DIODE; BAND; N2O; (N2O)-N-14-O-16; STRATOSPHERE; (CH4)-C-12; O-3 AB The temperature dependence of N2 foreign gas broadening coefficients for eight R-branch transitions in the nu3 fundamental of (N2O)-N-14-O-16 have been measured at 135, 176, 210 and 295 K by tunable diode laser spectroscopy. In approximate agreement with the theoretical value of 0.75 for n in the relation gamma(L)0(T)/gamma(L)0(T0) = (T0/T)n for quadrupole-quadrupole collisional interactions, n ranged from 0.66 to 0.71. We observed a distinct dependence between J and the exponent n in the range between R(15) and R(43). C1 WESTERN WASHINGTON STATE UNIV,DEPT CHEM,BELLINGHAM,WA 98225. RP LOEWENSTEIN, M (reprint author), NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035, USA. NR 26 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0584-8539 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD SEP PY 1992 VL 48 IS 9 BP 1243 EP 1248 DI 10.1016/0584-8539(92)80261-T PG 6 WC Spectroscopy SC Spectroscopy GA JP756 UT WOS:A1992JP75600006 ER PT J AU HILLMAN, JJ REUTER, DC JENNINGS, DE BJORAKER, GL BLASS, WE AF HILLMAN, JJ REUTER, DC JENNINGS, DE BJORAKER, GL BLASS, WE TI EXTRATERRESTRIAL SPECTROSCOPY - FOREIGN-GAS BROADENING OF PROPANE AS IT APPLIES TO THE ATMOSPHERE OF TITAN SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article ID VOYAGER INFRARED OBSERVATIONS; PARAMETERS; ABUNDANCE; REGION; CM-1 AB Propane spectra in the upsilon21 band near 748 cm-1 were observed with an instrumental resolution of 0.0025 cm-1. These data were obtained at the National Optical Astronomy Observatory, Tucson, AZ using the FTS spectrometer at the National Solar Observatory McMath telescope facility. The spectra included foreign-gas broadening due to He, H-2 and N2. All of these measurements were carried out at a temperature of 175 K. The following broadening coefficients (in cm-1 atm-1) are obtained at 175 K:0.128(19) for C3H8-He, 0.146(15) for C3H8-N2, and 0.241(19) for C3Hg-H2. These results are consistent with previous room-temperature measurements when a T-1/2 scaling law is invoked. C1 UNIV TENNESSEE,DEPT PHYS & ASTRON,KNOXVILLE,TN 37996. RP HILLMAN, JJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,MAIL CODE 690,GREENBELT,MD 20771, USA. RI Blass, William/A-2792-2008; Jennings, Donald/D-7978-2012 NR 33 TC 5 Z9 5 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0584-8539 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD SEP PY 1992 VL 48 IS 9 BP 1249 EP 1255 DI 10.1016/0584-8539(92)80262-U PG 7 WC Spectroscopy SC Spectroscopy GA JP756 UT WOS:A1992JP75600007 ER PT J AU SMITH, MAH RINSLAND, CP DEVI, VM BENNER, DC AF SMITH, MAH RINSLAND, CP DEVI, VM BENNER, DC TI TEMPERATURE-DEPENDENCE OF BROADENING AND SHIFTS OF METHANE LINES IN THE NU(4) BAND SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article ID 720-NM WAVELENGTH REGION; TUNABLE DIODE-LASER; INFRARED LINES; WATER-VAPOR; NITROGEN; (CH4)-C-12; LINEWIDTHS; STRENGTHS; WIDTHS; NU-4 AB We have recorded high-resolution absorption spectra of methane broadened by dry air and by N2 at temperatures from -63 to 41-degrees-C using a Fourier transform spectrometer. These spectra have been analyzed to determine pressure broadening and line-shift coefficients, along with their temperature dependences, for 148 lines in the V4 fundamental band of (CH4)-C-12. The experimental uncertainties for lines with J" less-than-or-equal-to 10 are generally <2% for the broadening coefficient b(L)0, 6-12% for its temperature dependence exponent n, 6-20% for the line-shift coefficient delta0, and 20-40% for its temperature dependence coefficient delta'; for J" > 10 the experimental uncertainties are somewhat larger. These results, especially for N2-broadening, are in excellent agreement with other recent measurements. Since the present results cover a wide range of rotational quantum numbers (J" up to 14), the variation of the temperature dependence of the half-widths and shifts from line to line within the nu4 band is also examined. C1 COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23187. RP SMITH, MAH (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 401A,HAMPTON,VA 23665, USA. NR 19 TC 57 Z9 58 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0584-8539 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD SEP PY 1992 VL 48 IS 9 BP 1257 EP 1272 DI 10.1016/0584-8539(92)80263-V PG 16 WC Spectroscopy SC Spectroscopy GA JP756 UT WOS:A1992JP75600008 ER PT J AU SPENCER, MN CHACKERIAN, C FLANNERY, C STEINFELD, JI AF SPENCER, MN CHACKERIAN, C FLANNERY, C STEINFELD, JI TI TEMPERATURE-DEPENDENCE OF NITROGEN BROADENING OF OZONE NU(3) ROVIBRATIONAL TRANSITIONS SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article ID MU-M; AIR; LINES; COEFFICIENTS; HALFWIDTHS; REGION; PARAMETERS; LINEWIDTHS; WIDTHS; SHIFTS AB We report N2-broadening coefficients for rovibrational transitions of the nu3 band of ozone in the temperature range 180-296 K. We assume a power law dependence of the temperature for these coefficients, with a temperature exponent n. For the 21 transitions we measured, the average value of n is 0.74 and is well within experimental error of the theoretically predicted value of 0.77. The significance of this parameter in modeling atmospheric IR absorbance due to ozone is discussed. C1 MIT,DEPT CHEM,CAMBRIDGE,MA 02139. RP SPENCER, MN (reprint author), NASA,AMES RES CTR,ATMOSPHER PHYS RES BRANCH,MOFFETT FIELD,CA 94035, USA. NR 26 TC 14 Z9 14 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0584-8539 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD SEP PY 1992 VL 48 IS 9 BP 1273 EP 1281 DI 10.1016/0584-8539(92)80264-W PG 9 WC Spectroscopy SC Spectroscopy GA JP756 UT WOS:A1992JP75600009 ER PT J AU MCLAUGHLIN, WI MILLER, SL AF MCLAUGHLIN, WI MILLER, SL TI AN EPISTEMOLOGICAL USE OF NONSTANDARD ANALYSIS TO ANSWER ZENO OBJECTIONS AGAINST MOTION SO SYNTHESE LA English DT Article AB Three of Zeno's objections to motion are answered by utilizing a version of nonstandard analysis, internal set theory, interpreted within an empirical context. Two of the objections are without force because they rely upon infinite sets, which always contain nonstandard real numbers. These numbers are devoid of 'numerical meaning', and thus one cannot render the judgment that an object is, in fact, located at a point in spacetime for which they would serve as coordinates. The third objection, 'an arrow never appears to be moving', is answered by showing that it only applies to a finite number of instants of time. A theory of motion is also advanced; it consists of a finite series of contiguous infinitesimal steps. The theory is immune to Zeno's first two objections because the number of steps is finite and each lies outside the domain of observation. 'Present motion' is hypothesized to be an unobservable process taking place within each step. The fact of motion is apparent through a summing (Riemann integration) of the steps. RP MCLAUGHLIN, WI (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 12 Z9 12 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0039-7857 J9 SYNTHESE JI Synthese PD SEP PY 1992 VL 92 IS 3 BP 371 EP 384 DI 10.1007/BF00414288 PG 14 WC History & Philosophy Of Science; Philosophy SC History & Philosophy of Science; Philosophy GA JP135 UT WOS:A1992JP13500003 ER PT J AU ROZAS, LP AF ROZAS, LP TI COMPARISON OF NEKTON HABITATS ASSOCIATED WITH PIPELINE CANALS AND NATURAL CHANNELS IN LOUISIANA SALT MARSHES SO WETLANDS LA English DT Article DE PIPELINE CANALS; FISHERIES IMPACT; MARSH SURFACE; LOUISIANA AB Nekton of Louisiana coastal marshes was sampled approximately twice monthly between June 1990 and May 1991 (1) on marshes adjacent to canals and on natural marshes with flumes and (2) within canals and natural channels using a small trawl. Canals constructed using two different methods (flotation and push) were studied. Dagger-blade grass shrimp Palaemonetes pugio, blue crabs Callinectes sapidus, Gulf killifish Fundulus grandis, diamond killifish Adinia xenica, brown shrimp Penaeus aztecus, and sheepshead minnows Cyprinodon variegatus dominated catches in terms of numbers and biomass on marshes as well as in canals and natural channels. Although densities of some species differed among the various sites that were sampled (e.g., dominant cyprinodonts were most abundant in creek tributaries), densities in canal and natural channel habitats were not significantly different. Predator encounter rates in canals and natural channels were similar, suggesting that the value of habitat in canals may increase over time as slumping decreases depth and steepness of bottom profiles and creates shallow subtidal refugia along the canal-marsh interface. The nursery function of canals open to tidal flushing is probably enhanced by the presence of fringing marshes, which provide habitat for nekton at high tide. RP ROZAS, LP (reprint author), NATL MARINE FISHERIES SERV,4700 AVE U,GALVESTON,TX 77551, USA. NR 0 TC 20 Z9 22 U1 0 U2 5 PU SOC WETLAND SCIENTISTS PI LAWRENCE PA 810 E TENTH ST, P O BOX 1897, LAWRENCE, KS 66044 SN 0277-5212 J9 WETLANDS JI Wetlands PD SEP PY 1992 VL 12 IS 2 BP 136 EP 146 PG 11 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA JN108 UT WOS:A1992JN10800008 ER PT J AU IGA, I RAO, MVVS SRIVASTAVA, SK NOGUEIRA, JC AF IGA, I RAO, MVVS SRIVASTAVA, SK NOGUEIRA, JC TI FORMATION OF NEGATIVE-IONS BY ELECTRON-IMPACT ON SIF4 AND CF4 SO ZEITSCHRIFT FUR PHYSIK D-ATOMS MOLECULES AND CLUSTERS LA English DT Article AB First measurements of cross sections for the formation of negative ions by electron attachment to SiF4 and CF4 are reported for an electron impact energy range of 0 to 50 eV. The energies at which the various ions appear and the positions at which the ionization efficiency curves peak have been obtained and compared with previous measurements. Thermochemical data have been used to predict and identify the various channels of dissociation. Cross sections for the production of ion pairs through the process of polar dissociation have also been measured. C1 UNIV FED SAO CARLOS,DEPT QUIM,BR-13560 SAO CARLOS,SP,BRAZIL. RP IGA, I (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Iga, Ione/C-1273-2015 NR 11 TC 34 Z9 34 U1 0 U2 3 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0178-7683 J9 Z PHYS D ATOM MOL CL JI Z. Phys. D-Atoms Mol. Clusters PD SEP PY 1992 VL 24 IS 2 BP 111 EP 115 PG 5 WC Physics, Atomic, Molecular & Chemical SC Physics GA JQ040 UT WOS:A1992JQ04000004 ER PT J AU HOENK, ME GRUNTHANER, PJ GRUNTHANER, FJ TERHUNE, RW FATTAHI, M TSENG, HF AF HOENK, ME GRUNTHANER, PJ GRUNTHANER, FJ TERHUNE, RW FATTAHI, M TSENG, HF TI GROWTH OF A DELTA-DOPED SILICON LAYER BY MOLECULAR-BEAM EPITAXY ON A CHARGE-COUPLED DEVICE FOR REFLECTION-LIMITED ULTRAVIOLET QUANTUM EFFICIENCY SO APPLIED PHYSICS LETTERS LA English DT Article ID SURFACE AB We have used low-temperature silicon molecular beam epitaxy to grow a delta-doped silicon layer on a fully processed charge-coupled device (CCD). The measured quantum efficiency of the delta-doped backside-thinned EG&G Reticon CCD is in agreement with the reflection limit for light incident on the back surface in the spectral range of 260-600 nm. The 2.5 nm silicon layer, grown at 450-degrees-C, contained a boron delta-layer with surface density approximately 2 X 10(14) cm-2. Passivation of the surface was done by steam oxidation of a nominally undoped 1.5 nm Si cap layer. The UV quantum efficiency was found to be uniform and stable with respect to thermal cycling and illumination conditions. C1 EG&G RETICON,SUNNYVALE,CA 94086. RP HOENK, ME (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 18 TC 48 Z9 48 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD AUG 31 PY 1992 VL 61 IS 9 BP 1084 EP 1086 DI 10.1063/1.107675 PG 3 WC Physics, Applied SC Physics GA JK802 UT WOS:A1992JK80200025 ER PT J AU GLEISER, M KOLB, EW AF GLEISER, M KOLB, EW TI FLUCTUATION-DRIVEN ELECTROWEAK PHASE-TRANSITION SO PHYSICAL REVIEW LETTERS LA English DT Article ID BARYON-NUMBER VIOLATION; EARLY UNIVERSE; SYMMETRY BEHAVIOR; HIGH-TEMPERATURE; BARYOGENESIS; ASYMMETRY; MODEL; GAUGE AB We examine the dynamics of the electroweak phase transition in the early Universe. For Higgs boson masses in the range 57 less-than-or-equal-to m(H) less-than-or-equal-to 150 GeV and top quark masses less than 200 GeV, regions of symmetric and asymmetric vacuum coexist to below the critical temperature, due to efficient thermal nucleation of subcritical fluctuations of the asymmetric phase within the symmetric phase. We propose that the transition to the asymmetric vacuum is completed by percolation of these fluctuations. Our results are relevant to scenarios of baryogenesis that invoke a weakly first-order electroweak transition. C1 FERMI NATL ACCELERATOR LAB,NASA,CTR ASTROPHYS,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP GLEISER, M (reprint author), DARTMOUTH COLL,DEPT PHYS & ASTRON,HANOVER,NH 03755, USA. NR 28 TC 55 Z9 55 U1 0 U2 2 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD AUG 31 PY 1992 VL 69 IS 9 BP 1304 EP 1307 DI 10.1103/PhysRevLett.69.1304 PG 4 WC Physics, Multidisciplinary SC Physics GA JK864 UT WOS:A1992JK86400004 ER PT J AU NOEVER, DA AF NOEVER, DA TI SCALING LAWS FOR BUCKLING INSTABILITY IN MONOLAYER NETWORKS SO PHYSICAL REVIEW LETTERS LA English DT Article RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,ES76,HUNTSVILLE,AL 35812, USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD AUG 31 PY 1992 VL 69 IS 9 BP 1473 EP 1473 DI 10.1103/PhysRevLett.69.1473 PG 1 WC Physics, Multidisciplinary SC Physics GA JK864 UT WOS:A1992JK86400048 ER PT J AU HASSAN, AA TUNG, C SANKAR, LN AF HASSAN, AA TUNG, C SANKAR, LN TI EULER SOLUTIONS FOR SELF-GENERATED ROTOR BLADE-VORTEX INTERACTIONS SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE AERODYNAMICS; ROTOR; BLADE-VORTEX; INTERACTIONS AB A finite-difference procedure has been developed for the prediction of three-dimensional rotor blade-vortex interactions. The interaction velocity field was obtained through a non-linear superposition of the rotor flow field, computed using the unsteady three-dimensional Euler equations, and the embedded vortex wake flow field, computed using the law of Biot-Savart. In the Euler model, near wake rotational effects were simulated using the surface velocity 'transpiration' approach. As a result, a modified surface boundary condition was prescribed and enforced at each time step of the computations to satisfy the tangency boundary condition. For supercritical interactions using an upstream-generated vortex, accuracy of the numerical results were found to rely on the user-specified vortex core radius and vortex strength. For the more general self-generated subcritical interactions, vortex wake trajectories were computed using the lifting-line helicopter/rotor trim code CAMRAD. For these interactions, accuracy of the results were found to rely heavily on the CAMRAD-predicted vortex strength, vortex orientation with respect to the blade, and to a large extent on the user-specified vortex core radius. Results for the one-seventh scale model OLS rotor and for a non-lifting rectangular blade having a NACA0012 section are presented. Comparisons with the experimental wind-tunnel data are also made. C1 GEORGIA INST TECHNOL,SCH AEROSP ENGN,ATLANTA,GA 30332. NASA,AMES RES CTR,AVSCOM,AEROFLIGHTDYNAM DIRECTORATE,MOFFETT FIELD,CA 94035. RP HASSAN, AA (reprint author), MCDONNELL DOUGLAS HELICOPTER CO,AERODYNAM ACOUST,5000 E MCDOWELL RD,MESA,AZ 85205, USA. NR 42 TC 4 Z9 4 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD AUG 30 PY 1992 VL 15 IS 4 BP 427 EP 451 DI 10.1002/fld.1650150405 PG 25 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA JG785 UT WOS:A1992JG78500004 ER PT J AU JONES, JH CAPOBIANCO, CJ DRAKE, MJ AF JONES, JH CAPOBIANCO, CJ DRAKE, MJ TI SIDEROPHILE ELEMENTS AND THE EARTHS FORMATION SO SCIENCE LA English DT Article ID METAL C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP JONES, JH (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. OI O'Neill, Hugh/0000-0001-7018-9783 NR 7 TC 24 Z9 24 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 28 PY 1992 VL 257 IS 5074 BP 1281 EP 1282 DI 10.1126/science.257.5074.1281 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JL050 UT WOS:A1992JL05000035 PM 17742758 ER PT J AU PAL, SK WANG, L AF PAL, SK WANG, L TI FUZZY MEDIAL AXIS TRANSFORMATION (FMAT) - PRACTICAL FEASIBILITY SO FUZZY SETS AND SYSTEMS LA English DT Article DE FUZZY MEDIAL AXIS TRANSFORMATION (FMAT); FUZZY DISK; FUZZY GEOMETRY; IMAGE PROCESSING REPRESENTATION ID IMAGE; SKELETON AB The Fuzzy Medial Axis Transformation (FMAT) of a fuzzy set f is a set of fuzzy disks whose sup is f. Unfortunately, specifying the FMAT sometimes requires more storage space than specifying f itself. The present paper describes some techniques to improve the compact representation of FMAT; thereby making it practically feasible and useful. The algorithms involve reduction of redundancy in FMAT, its approximation, and reduction of the searching spaces for its computation. The computational aspects for the convenience of writing an efficient program have also been described. A concept of 'sponsoring capability' of a pixel is described in order to view the principle of removing redundancy in FMAT and to generate its approximation. Two kinds of approximations are made, namely, distributed approximation and optimum fuzzy compactness. The aforesaid features have been demonstrated on a gray image. RP PAL, SK (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SOFTWARE TECHNOL BRANCH PT4,HOUSTON,TX 77058, USA. NR 13 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0165-0114 J9 FUZZY SET SYST JI Fuzzy Sets Syst. PD AUG 25 PY 1992 VL 50 IS 1 BP 15 EP 34 DI 10.1016/0165-0114(92)90200-N PG 20 WC Computer Science, Theory & Methods; Mathematics, Applied; Statistics & Probability SC Computer Science; Mathematics GA JP074 UT WOS:A1992JP07400002 ER PT J AU SAUNDERS, RS SPEAR, AJ ALLIN, PC AUSTIN, RS BERMAN, AL CHANDLEE, RC CLARK, J DECHARON, AV DEJONG, EM GRIFFITH, DG GUNN, JM HENSLEY, S JOHNSON, WTK KIRBY, CE LEUNG, KS LYONS, DT MICHAELS, GA MILLER, J MORRIS, RB MORRISON, AD PIERESON, RG SCOTT, JF SHAFFER, SJ SLONSKI, JP STOFAN, ER THOMPSON, TW WALL, SD AF SAUNDERS, RS SPEAR, AJ ALLIN, PC AUSTIN, RS BERMAN, AL CHANDLEE, RC CLARK, J DECHARON, AV DEJONG, EM GRIFFITH, DG GUNN, JM HENSLEY, S JOHNSON, WTK KIRBY, CE LEUNG, KS LYONS, DT MICHAELS, GA MILLER, J MORRIS, RB MORRISON, AD PIERESON, RG SCOTT, JF SHAFFER, SJ SLONSKI, JP STOFAN, ER THOMPSON, TW WALL, SD TI MAGELLAN MISSION SUMMARY SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB Magellan started mapping the planet Venus on September 15, 1990, and after one cycle (one Venus day or 243 Earth days) had mapped 84% of the planet's surface. This returned an image data volume greater than all past planetary missions combined. Spacecraft problems were experienced in flight. Changes in operational procedures and reprogramming of onboard computers minimized the amount of mapping data lost. Magellan data processing is the largest planetary image-processing challenge to date. Compilation of global maps of tectonic and volcanic features, as well as impact craters and related phenomena and surface processes related to wind, weathering, and mass wasting, has begun. The Magellan project is now in an extended mission phase, with plans for additional cycles out to 1995. The Magellan project will fill in mapping gaps, obtain a global gravity data set between mid-September 1992 and May 1993, acquire images at different view angles, and look for changes on the surface from one cycle to another caused by surface activity such as volcanism, faulting, or wind activity. RP SAUNDERS, RS (reprint author), JET PROP LAB,MAIL STOP 91-69,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 38 TC 109 Z9 112 U1 4 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13067 EP 13090 PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100001 ER PT J AU DAVIES, ME COLVIN, TR ROGERS, PG CHODAS, PW SJOGREN, WL AKIM, EL STEPANYANTZ, VA VLASOVA, ZP ZAKHAROV, AI AF DAVIES, ME COLVIN, TR ROGERS, PG CHODAS, PW SJOGREN, WL AKIM, EL STEPANYANTZ, VA VLASOVA, ZP ZAKHAROV, AI TI THE ROTATION PERIOD, DIRECTION OF THE NORTH-POLE, AND GEODETIC CONTROL NETWORK OF VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID WORKING-GROUP; SPIN VECTOR; SATELLITES; ELEMENTS; PLANETS AB Before the Magellan mission, the best estimates of the rotation rate and pole direction of venus were derived from Earth-based radar measurements. A new determination of these rotational parameters has now been made from an analysis of Magellan radar images. Control points were selected from the north polar region and measured on full-resolution radar strips. the measurements were entered into a least squares adjustment to solve for the pole direction and rotation rate of Venus, as well as the coordinates of the control points themselves. The current data set contains 3893 measurements of 571 points on 560 radar strips. Spacecraft ephemeris errors dominate the measurement errors. One technique used to remove ephemeris errors is to adjust the averaged orbital inclination and argument of periapsis for each orbit. In a more precise technique used for selected blocks of orbits, an improved spacecraft ephemeris is computed by optimally fitting measurements of additional points at all latitudes of the radar strips together with Earth-based spacecraft radiometric tracking measurements. In a separate experiment, measurements were made of a few points common to both Venera 15/16 and Magellan images. The long time baseline between the images should have led to an accurate determination of the rotation period and pole direction of Venus. However, the measurement residuals were unexpectedly large, and these solutions are not currently considered reliable. A rotation period estimate of 243.0185 +/- 0.0001 days was determined via the ephemeris improvement technique applied simultaneously to two overlapping orbit blocks with many common points and separated by two full Venus rotations. Using this period value, the control network computations estimated the north pole directions as right ascenson = 272.76-degrees +/- 0.02-degrees and declination = 67.16-degrees +/- 0.01-degrees in the J2000 frame. C1 KELDYSH INST APPL MATH,MOSCOW,USSR. JET PROP LAB,PASADENA,CA 91109. MOSCOW RADIOENGN & ELECTR INST,MOSCOW,USSR. RP DAVIES, ME (reprint author), RAND CORP,1700 MAIN ST,POB 2138,SANTA MONICA,CA 90407, USA. NR 21 TC 18 Z9 18 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13141 EP 13151 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100005 ER PT J AU HEAD, JW CRUMPLER, LS AUBELE, JC GUEST, JE SAUNDERS, RS AF HEAD, JW CRUMPLER, LS AUBELE, JC GUEST, JE SAUNDERS, RS TI VENUS VOLCANISM - CLASSIFICATION OF VOLCANIC FEATURES AND STRUCTURES, ASSOCIATIONS, AND GLOBAL DISTRIBUTION FROM MAGELLAN DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID INITIAL ANALYSIS; IMPACT CRATERS; BETA-REGIO; EVOLUTION; ORIGIN; REFLECTIVITY; CONVECTION; MORPHOLOGY; VENERA-15; ROUGHNESS AB A preliminary analysis of a global survey of Magellan data covering over 90% of the surface and designed to document the characteristics, location, and dimensions of all major volcanic features on Venus has revealed over 1660 landforms and deposits. These include over 550 shield fields (concentrations of small volcanoes <20 km in diameter), 274 intermediate volcanoes between 20 and 100 km diameter with a variety of morphologies, 156 large volcanoes in excess of 100 km diameter, 86 calderalike structures independent of those associated with shield volcanoes and typically 60-80 km in diameter, 175 coronae (annulus of concentric ridges or fractures), 259 archnoids (inner concentric and outer radial network pattern of fractures and ridges), 50 novae (focused raidal fractures forming stellae patterns), and 53 lava flood-type flow fields and 50 sinuous lava channels (all of which are in excess of 10(2)-10(3) km in length). The vast majority of landorms are consistent with basaltic compositions; possible exceptions include steep-sided domes and festoons, which may represent more evolved compositions, and sinuous rilles, which may represent more fluid, possibly ultramafic magma. The range of morphologies indicates that a spectrum of intrusive and extrusive processes have operated on Venus. Little evidence was found for extensive pyroclastic deposits or landforms, consist with the inhibition of volatile exsolution and consequent disruption by the high surface atmospheic pressure. The large size of many volcanic features is evidence for the presence of very large magma reservoirs. The scale of resurfacing implied by individual features and deposits is typically much less than 125,000 km2. The areal distribution, abundance, and size distribution relationships of shield fields, arachnoids, novae, large volcanoes, and coronae strongly suggest that they are the surface manufestation of mantly plumes or hot spots and that the different morphologies represent variations in plume size and stage and thermal structure of the lithosphere. Maps of the global distribution of volcanic features show that they are broadly distributed globally, in contrast to the plate boundary concentrations typical of Earth. However, they are not randomly distributed on the surface of Venus. An observed deificiency of many volcanic features in several lowland areas of Venus may be due to an altitude-dependent influence of atmospheric pressure on volatile exsolution and the production of neutral buoyancy zones sufficient to form magma reservoirs; this would favor laval flood and sinuous channels at low elevations and edifices and reservoir-related features at higher elevations. A major concentration of volcanic features is observed in the Beta/Atla/Themis region, an area covering about 20% of the planet and centered on the equator. This region is unique in that it is the site of local concentrations of volcanic features with concentrations 2-4 times the global average, an interlocking network of rift and deformation zones, several broad rises several thousand kilometers in diameter with associated positive gravity anomalies and tectonic junctions, and evidence for volcanically embayed impact craters. Although the region as a whole does not appear to be anomalously older or younger than the rest of Venus, there is evidence that the most ercent volcanic acitivity on the planet occurs here, and the presence of this series of concentrations suggests that themantle in this region is anomalous. Analysis of the impact crater population shows that it cannot be distinguished from a completely spatially random population (Philips et al., this issue), and several end-member models for this distribution are possible: (1) single production age or "soamoddic or catastrophic volcanism" model: craters have accumulated subsequent to a global volcanic resurfacing event about one-half billion years ago (Schaber et al., this issue); (2) vertical equilibrium or "leaky planet" model: craters are removed by slow accumulation of lava over the whole planet leading to a range of volcanic degradation states for craters; (3) regional resurfacing or "collage" or "cookie-cutter" model: craters are removed largely instantaneously by superposition of features and deposits; the horizontal scale of resurfacing does not exceed the horizontal scale of randomness of the crater population. Our data on the scale and location of resurfacing are consistent with the regional resurfacing model and with the catastrophic resurfacing model. The nature and abundance of impact craters definitely degraded by volcanism also favor these two models, although uncertainty exists as to whether all such craters have veen detected. Although a process toward the regional resurfacing end-member model presently seems most plausible, distinction between the three models requires an understanding of the mode and timing of emplacement of the volcanic plains that make up the majority of the surface and which are not clearly related to the edifices and features mapped in this study. In addition, the resurfacing mechanisms involved in the catastrophic resurfacing models are not yet explicitly enough formulated to test with the existing data. An equilibrium resurfacing model implies a volcanic flux of 0.5 km3/yr, a value similar to the present rate of intraplate volcanism on Earth (0.3-0.5 km3/yr). This value is broadly comparable to that implied by the edifices and deposits on Venus mapped in this study. Geologically recent volcanism on Venus is dominated by features interpreted to be related to mantle plumes. C1 UCL, UNIV LONDON OBSERV, LONDON NW7 2QS, ENGLAND. JET PROP LAB, PASADENA, CA 91109 USA. RP HEAD, JW (reprint author), BROWN UNIV, DEPT GEOL SCI, PROVIDENCE, RI 02912 USA. NR 101 TC 258 Z9 262 U1 2 U2 32 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 AUG 25 PY 1992 VL 97 IS E8 BP 13153 EP 13197 PG 45 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100006 ER PT J AU SOLOMON, SC SMREKAR, SE BINDSCHADLER, DL GRIMM, RE KAULA, WM MCGILL, GE PHILLIPS, RJ SAUNDERS, RS SCHUBERT, G SQUYRES, SW STOFAN, ER AF SOLOMON, SC SMREKAR, SE BINDSCHADLER, DL GRIMM, RE KAULA, WM MCGILL, GE PHILLIPS, RJ SAUNDERS, RS SCHUBERT, G SQUYRES, SW STOFAN, ER TI VENUS TECTONICS - AN OVERVIEW OF MAGELLAN OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID MANTLE FLOW TECTONICS; ISHTAR-TERRA; INITIAL ANALYSIS; BETA-REGIO; LITHOSPHERIC FLEXURE; GRAVITY-ANOMALIES; THERMAL-GRADIENT; APHRODITE TERRA; BANDED TERRAIN; LAKSHMI-PLANUM AB The nearly global radar imaging and altimetry measurements of the surface of Venus obtained by the Magellan spacecraft have revealed that deformational features of a wide variety of styles and spatial scales are nearly ubiquitous on the planet. Many areas of Venus record a superposition of different episodes of deformation and volcanism. This deformation is manifested both in areally distributed strain of modest magnitude, such as families of graben and wrinkle ridges at a few to a few tens of kilometers spacing in many plains regions, as well as in zones of concentrated lithospheric extension and shortening. The common coherence of strain patterns over hundreds of kilometers implies that even many local features reflect a crustal response to mantle dynamic processes. Ridge belts and mountain belts, which have characteristic widths and spacings of hundreds of kilometers, represent successive degrees of lithospheric shortening and crustal thickening. The mountain belts of Venus, as on Earth, show widespread evidence for lateral extension both during and following active crustal compression. Venus displays two principal geometrical variations on lithospheric extension: the quasi-circular coronae (75-2600 km diameter) and broad rises with linear rift zones having dimensions of hundreds to thousands of kilometers. Both are sites of significant volcanic flux, but horizontal displacements may be limited to only a few tens of kilometers. Few large-offset strike slip faults have been observed, but limited local horizontal shear is accommodated across many zones of crustal stretching or shortening. Several large-scale tectonic features have extremely steep topographic slopes (in excess of 20-degrees-30-degrees) over a 10-km horizontal scale; because of the tendency for such slopes to relax by ductile flow in the middle to lower crust, such regions are likely to be tectonically active. In general, the preserved record of global tectonics of Venus does riot resemble oceanic plate tectonics on Earth, wherrin large, rigid plates are separated by narrow zones of deformation along plate boundaries. Rather tectonic strain on Venus typically involves deformation distributed across broad zones tens to a few hundred kilometers wide separated by comparatively undeformed blocks having dimensions of hundreds of kilometers. These characteristics are, shared with actively deforming continental regions on Earth. The styles and scales of tectonic deformation on Venus may be consequences of three differences from the Earth: (1) The absence of a hydrological cycle and significant erosion dictates that multiple episodes of deformation are typically well-preserved. (2) A high surface temperature and thus a significantly shallower onset of ductile behavior in the middle to lower crust gives rise to a rich spectrum of smaller-scale deformational features. (3) A strong coupling of mantle convection to the upper mantle portion of the lithosphere, probably because Venus lacks a mantle low-viscosity zone, leads to crustal stress fields that are coherent over large distances. The lack of a global system of tectonic plates on Venus is likely a combined consequence of a generally lesser strength and more limited horizontal mobility of the lithosphere than C1 UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. UNIV MASSACHUSETTS,DEPT GEOL & GEOG,AMHERST,MA 01003. WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130. JET PROP LAB,PASADENA,CA 91109. CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853. RP SOLOMON, SC (reprint author), MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,BLDG 54-520,CAMBRIDGE,MA 02139, USA. NR 96 TC 208 Z9 210 U1 8 U2 36 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13199 EP 13255 PG 57 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100007 ER PT J AU SCHABER, GG STROM, RG MOORE, HJ SODERBLOM, LA KIRK, RL CHADWICK, DJ DAWSON, DD GADDIS, LR BOYCE, JM RUSSELL, J AF SCHABER, GG STROM, RG MOORE, HJ SODERBLOM, LA KIRK, RL CHADWICK, DJ DAWSON, DD GADDIS, LR BOYCE, JM RUSSELL, J TI GEOLOGY AND DISTRIBUTION OF IMPACT CRATERS ON VENUS - WHAT ARE THEY TELLING US SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID INITIAL ANALYSIS; SCHEMATIC MODEL; BASIN FORMATION; MAGELLAN; MARS; GRAVITY; MOON; MORPHOLOGY; MERCURY; ORIGIN AB Magellan has revealed an ensemble of impact craters on Venus that is unique in many important ways. We have complied a data base describing the 842 craters on 89% of Venus' surface mapped through orbit 2578. (The craters range in diameter from 1.5 to 280 km.) We have studied the distribution, size-density, morphology, geology, and associated surface properties of these craters both in the aggregate and, for some craters, in greater detail. We find that (1) the spatial distribution of craters is highly uniform; (2) the size-density distribution of large craters (diameters greater-than-or-equal-to 35 km) is similar to the young crater populations on other terrestrial planets but at a much lower density that indicates an average age of only about 0.5 Ga (based on the estimated population of Venus-crossing asteroids); (3) unlike the case on other planets, the density of small craters (diameters less-than-or-equal-to 35 km) declines rapidly with decreasing diameters because of atmospheric filtering; (4) the spectrum of crater modification differs greatly from that on other planets: 62 % of all craters are pristine, only 4 % are embayed by lavas, and the remainder are affected by tectonism, but none are severely and progressively depleted (as extrapolated from the size-density distribution of larger craters); (5) large craters have a progression of morphologies generally similar to those on other planets, but small craters are typically irregular or multiple rather than bowl shaped; (6) diffuse radar-bright or -dark features surround some craters, and 367 similar diffuse 'splotches' with no central crater are observed; and (7) other crater features unique to Venus include radar-bright or -dark parabolic arcs opening westward and extensive outflows originating in crater ejecta. The first three of these observations are entirely unexpected. We interpret them as indicating that the planet's cratering record was erased by a global resurfacing event or events, the latest ending about 0.5 Ga, after which volcanic activity declined (but did not cease entirely). Since the last resurfacing event, a maximum of 10 % of the planet has been resurfaced and only about 4 % of the craters have been obliterated. Convective thermal evolution models support this interpretation (Arkani-Hamed and Toksoz, 1984). Observations 3-7 confirm quantitatively the expectation that the dense atmosphere of Venus has strongly affected the production of craters. Large impactors have been relatively unaffected, intermediate-sized ones have been fragmented and have produced overlapping or multiple craters, a narrow size range has produced shock-induced 'splotches' but no craters, and the smallest bodies have had no observable effect on the surface. The number of craters eliminated by the 'atmospheric filter" is enormous, about 98 % of the craters between 2 and 35 km in diameter that Magellan might have observed on a hypothetical airless Venus. Unique crater-related features such as parabolas and outflow deposits demonstrate the roles of Venus' high atmospheric density and temperature in modifying the craw formation process. Finally, heavily fractured craters and lava-embayed craters are found to have higher than average densities along the major fracture belts and rifted uplands connecting Aphrodite Terra and Ada, Beta, Themis, and Phoebe regiones. These craters thus provide physical evidence for recent volcanic and tectonic activity at a low level. C1 NASA,WASHINGTON,DC 20546. UNIV ARIZONA,DEPT PLANETARY SCI,TUCSON,AZ 85721. US GEOL SURVEY,MENLO PK,CA 90425. RP SCHABER, GG (reprint author), US GEOL SURVEY,2255 N GEMINI DR,FLAGSTAFF,AZ 86001, USA. NR 124 TC 245 Z9 248 U1 6 U2 24 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13257 EP 13301 PG 45 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100008 ER PT J AU ARVIDSON, RE GREELEY, R MALIN, MC SAUNDERS, RS IZENBERG, N PLAUT, JJ STOFAN, ER SHEPARD, MK AF ARVIDSON, RE GREELEY, R MALIN, MC SAUNDERS, RS IZENBERG, N PLAUT, JJ STOFAN, ER SHEPARD, MK TI SURFACE MODIFICATION OF VENUS AS INFERRED FROM MAGELLAN OBSERVATIONS OF PLAINS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CIMA VOLCANIC FIELD; INITIAL ANALYSIS; CALIFORNIA AB In Sedna Planitia, clear stratigraphic relations can be discerned among volcanic flow units Young flows exhibit SAR specific cross section values similar to fresh terrestrial basalt flows, whereas older flows exhibit backscatter signatures similar to degraded terrestrial basalt flows. Total degradation of approximately 1 m depth over approximately 0.6 b.y. is inferred for the Sedna area from radar signatures, impact crater abundances, and ejecta superposition relations with respect to volcanic flow units. Analyses of parabolic ejecta deposits associated with the crater Stuart imply that the material is typically centimeters in thickness. A relatively small fraction (approximately 10%) of Venusian impact craters exhibit prominent parabolic ejecta deposits. These craters are interpreted to be relatively young and parabolic deposits are interpreted to be dispersed by aeolian activity over at least tens of millions of years. The inferred dispersal rate (<10(-3)mu-m/yr) is too low to produce the degradation of flows at Sedna Planitia, and it is concluded that the dominant flow modification process is in situ weathering. In addition, elevation dependent weathering is inferred in western Ovda Regio, where plains above 6054 km radius have enhanced reflection coefficients as compared to adjacent plains at lower elevations. The inferred rate of generation of high reflection coefficient materials is no more than approximately 10(-2)mu-m/yr, based on the inability of aeolian activity to cover high-reflectivity surfaces with normal reflection coefficient materials and the ubiquitous nature of high-reflectivity surfaces at high elevations. Surface modification rates on Venus are orders of magnitude lower than on Earth. Venusian rates are also much lower than the inferred rate of aeolian dispersal of friable materials on Mars but are comparable to the estimated mte of weathering and erosion of Martian bedrock. Low surface modification rates imply that it will be possible to determine regional-scale age variations on Venus based on the degree of preservation of volcanic landforms and microwave signatures. C1 ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. ARIZONA STATE UNIV,CTR METEORITE STUDIES,TEMPE,AZ 85287. MALIN SPACE SCI SYST,SAN DIEGO,CA 92121. JET PROP LAB,PASADENA,CA 91109. RP ARVIDSON, RE (reprint author), WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130, USA. RI Izenberg, Noam/F-3952-2015 OI Izenberg, Noam/0000-0003-1629-6478 NR 30 TC 76 Z9 77 U1 2 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13303 EP 13317 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100009 ER PT J AU GREELEY, R ARVIDSON, RE ELACHI, C GERINGER, MA PLAUT, JJ SAUNDERS, RS SCHUBERT, G STOFAN, ER THOUVENOT, EJP WALL, SD WEITZ, CM AF GREELEY, R ARVIDSON, RE ELACHI, C GERINGER, MA PLAUT, JJ SAUNDERS, RS SCHUBERT, G STOFAN, ER THOUVENOT, EJP WALL, SD WEITZ, CM TI AEOLIAN FEATURES ON VENUS - PRELIMINARY MAGELLAN RESULTS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID VARIABLE FEATURES; WIND STREAKS; SEDIMENT TRANSPORT; INITIAL ANALYSIS; RADAR IMAGES; SAND DUNES; MARS; ATMOSPHERE; SURFACE; SPACEBORNE AB Magellan synthetic aperture radar data reveal numerous surface features that are attributed to aeolian, or wind processes. Wind streaks are the most common aeolian feature. They consist of radar backscatter patterns that are high, low, or mixed in relation to the surface on which they occur. A data base of more than 3400 wind streaks shows that low backscatter linear forms (long, narrow streaks) are the most common and that most streaks occur between 17-degrees-S to 30-degrees-S and 5-degrees-N to 53-degrees-N on smooth plains. Moreover, most streaks are associated with deposits from certain impact craters and some tectonically deformed terrains. We infer that both of these geological settings provide fine particulate material that can be entrained by the low-velocity winds on Venus. Turbulence and wind patterns generated by the topographic features with which many streaks are associated can account for differences in particle distributions and in the patterns of the wind streaks. Thus, some high backscatter streaks arc considered to be zones that are swept free of sedimentary particles to expose rough bedrock; other high backscatter streaks may be lag deposits of dense materials from which low-density grains have been removed (dense materials such as ilmenite or pyrite have dielectric properties that would produce high backscatter patterns). Wind streaks generally occur on slopes < 2-degrees and tend to be oriented toward the equator, consistent with the Hadley model of atmospheric circulation. In addition to wind streaks, other aeolian features on Venus include yardangs(?) and dune fields. The Aglaonice dune field, centered at 25-degrees-S, 340-degrees-E, covers approximately 1290 km2 and is located in an ejecta flow channel from the Aglaonice impact crater. The Meshkenet dune field, located at 67-degrees-N, 90-degrees-E, covers approximately 17,120 km2 in a valley between Ishtar Terra and Meshkenet Tessera. Wind streaks associated with both dune fields suggest that the dunes are of transverse forms in which the dune crests are perpendicular to the prevailing winds. Dunes on Venus signal the presence of sand-size (approximately 60 to 2,000-mu-m) grains. The possible yardangs are found at 9-degrees-N, 60.5-degrees-E, about 300 km southeast of the crater Mead. Although most aeolian features are concentrated in smooth plains near the equator, the occurrence of wind streaks is widespread, and some have been found at all latitudes and elevations. They demonstrate that aeolian processes operate widely on Venus. The intensity of wind erosion and deposits, however, varies with locality and is dependent on the wind regime and supply of particles. C1 WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130. JET PROP LAB,PASADENA,CA 91109. UNIV CALIF LOS ANGELES,IGPP,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. RP GREELEY, R (reprint author), ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287, USA. NR 66 TC 54 Z9 57 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13319 EP 13345 PG 27 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100010 ER PT J AU STOFAN, ER SHARPTON, VL SCHUBERT, G BAER, G BINDSCHADLER, DL JANES, DM SQUYRES, SW AF STOFAN, ER SHARPTON, VL SCHUBERT, G BAER, G BINDSCHADLER, DL JANES, DM SQUYRES, SW TI GLOBAL DISTRIBUTION AND CHARACTERISTICS OF CORONAE AND RELATED FEATURES ON VENUS - IMPLICATIONS FOR ORIGIN AND RELATION TO MANTLE PROCESSES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INITIAL ANALYSIS; BETA-REGIO; MAGELLAN; LITHOSPHERE; CONVECTION; MORPHOLOGY; TECTONICS; VOLCANISM; HOTSPOTS; DYNAMICS AB Coronae on Venus range from 60 to over 2000 km across and are characterized by a complex range of morphologies. The annuli around coronae range from about 10 to 150 km across and have tectonic features ranging from extensional to compressional to a combination of both. Topographically, coronae arc domes, plateaus, plateaus with interior lows, and rimmed depressions. A subset of features classified here as coronae corresponds to depressions and is interpreted to consist of large-scale calderas. A number of features have been identified with many of the basic characteristics of coronae (similar interior deformation, associations with volcanism, high topography) but lacking a distinct tectonic annulus. These features tend to be somewhat smaller than coronae and may represent "failed" coronae or coronae in an early stage of evolution. The size distribution of coronae and coronalike features with maximum widths greater than about 250 km is well represented by a power law of the form N(D) = kD(-alpha), where N is the number of coronae with maximum widths greater than D (km) and alpha = 3.05. The spatial distribution of coronae is not random; the features are concentrated in a few groups and along several chains. Coronae are similar in many morphologic characteristics to major volcanic shield structures and volcanic rises such as Western Eistla Regio. The largest corona, Artemis, is actually larger than several volcanic rises on Venus. Coronae and volcanic rises appear to be surface manifestations of mantle plumes. There is no evidence of any systematic variation in age along chains of coronae as occurs in hotspot chains on Earth. Instead, a number of multiple and overlapping coronae may indicate limited movement of the surface above a hotspot or mantle plume. The morphology and size distribution of coronae, highlands, and major shields suggest that mantle upwelling on Venus operates either on several spatial scales, with coronae representing smaller-scale upflows and major volcanic rises representing larger convective upwellings, or on several temporal scales, with coronae representing shorter duration upflows and major volcanic rises representing long-term upwellings. C1 UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853. LUNAR & PLANETARY INST,HOUSTON,TX 77058. RP STOFAN, ER (reprint author), JET PROP LAB,MAIL STOP 230-225,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 51 TC 174 Z9 176 U1 3 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13347 EP 13378 PG 32 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100011 ER PT J AU SENSKE, DA SCHABER, GG STOFAN, ER AF SENSKE, DA SCHABER, GG STOFAN, ER TI REGIONAL TOPOGRAPHIC RISES ON VENUS - GEOLOGY OF WESTERN EISTLA REGIO AND COMPARISON TO BETA-REGIO AND ATLA-REGIO SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INITIAL ANALYSIS; APHRODITE TERRA; VOLCANISM; TECTONICS; MAGELLAN; EVOLUTION AB Regional topographic rises in the equatorial region of Venus (Western Eistla Regio, Beta Regio, and Atla Regio) form a unique class of structures which on the basis of geologic mapping and geophysical data are interpreted to be sites of mantle upwelling or plumes. The geologically least complex of these regions is Western Eistla Regio, an elongated domical rise that contains the volcanoes Sif and Gula montes. Sif Mons is a large volcano (diameter > 100 km) whose local stratigraphy indicates that it has undergone a history marked by initial radial fracturing, widespread outpouring of lava, additional fracturing along its northern flank, and extrusion of lava that is either extremely fluid or was erupted at a high rate of effusion. Sif contains a 40-km-diameter summit caldera Within which are nested smaller calderas and pit structures. Theoretical considerations suggest multiple levels of magma emplacement within the volcano, with the primary reservoir residing in the crust below the edifice. Gula Mons is made up of multiple volcanic source regions and is associated with Guor Linea, a zone of lithospheric stretching, faulting, and rifting. The geologically complex highland of Beta Regio is a tectonic junction with three arms of Devana Chasma intersecting at Theia Mons. Magellan data reveal (1) the details of rifting and volcanism concentrated at Theia Mons, (2) that Rhea Mons is highly deformed and possesses characteristics of tesserae and whose origin as a volcano is placed in question, (3) that tesserae are a major unit, arrayed in a pattern around Theia from east to west starting on the eastern flank of Beta and continuing westward to the northern pan of Asteria Regio, (4) that the northern periphery of the highland contains coronae connected by fractures forming chains, and (.5) the presence of a deformed crater within Devana Chasma, split and extended in an east-west direction, indicating that pan of the rift has undergone as much as 20-30% extension. Like Beta, Atla Regio is a complex area of converging rifts (five separate arms) that are centered on the volcano Ozza Mons. The Magellan images show that volcanism and rifting have occurred contemporaneously at Ozza, with lava flows both covering and being crosscut by faults. A second volcano, Maat Mons, contributes to the infilling of the rift Dali Chasma and does not appear to be deformed by faulting. Two of the rifts at Atla contain chains of coronae, suggesting that upwelling along linear zones of extension has occurred. Beta, Atla, and Western Eistla am similar in that they are broad regional rises, are associated with major rift zones, have large apparent depths of isostatic compensation, and contain large volcanoes. Their associations with features mapped as coronae and tesserae are quite variable, suggesting that the detailed characteristics of the individual highlands are most likely linked to each areas local geologic environment. C1 US GEOL SURVEY,FLAGSTAFF,AZ 86001. JET PROP LAB,PASADENA,CA 91109. RP SENSKE, DA (reprint author), BROWN UNIV,DEPT GEOL SCI,BOX 1846,PROVIDENCE,RI 02912, USA. NR 34 TC 96 Z9 96 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13395 EP 13420 PG 26 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100013 ER PT J AU BAKER, VR KOMATSU, G PARKER, TJ GULICK, VC KARGEL, JS LEWIS, JS AF BAKER, VR KOMATSU, G PARKER, TJ GULICK, VC KARGEL, JS LEWIS, JS TI CHANNELS AND VALLEYS ON VENUS - PRELIMINARY-ANALYSIS OF MAGELLAN DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INITIAL ANALYSIS; CARBONATITE; SULFUR; CALCITE AB A preliminary survey of Magellan imagery reveals more than 200 newly discovered relic channel and valley landform complexes. For purposes of discussion the channels can be classed as simple, complex, and compound. Integrated valleys also occur. Simple channels include (1) sinuous rilles that closely resemble their lunar counterparts and (2) a newly recognized long sinuous form of high width-to-depth ratio and remarkably constant width. Herein designated canali, the most spectacular of these channels is 6800 km long. One of the compound channels, an outflow complex in Lada Terra, extends over 1200 km and is up to 30 km wide. Streamlined hills and spill relationships at a cross-axial ridge are similar to features in flood channels. Venusian channels have a global distribution with most of the large canali-type channels developed on volcanic plains. Alternative hypotheses for the channel-forming processes include genesis by the following erosive fluids: ultramafic silicate melts, sulfur, and carbonate lavas. Each of these causative agents has profound implications for Venusian planetology. The remote possibility of an aqueous origin. indicated by apparent regime behavior of the active channeling process, cannot be excluded with absolute certainty. C1 JET PROP LAB,PASADENA,CA 91109. RP BAKER, VR (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB,GOULD SIMPSON BLDG,TUCSON,AZ 85721, USA. RI Komatsu, Goro/I-7822-2012 OI Komatsu, Goro/0000-0003-4155-108X NR 43 TC 103 Z9 103 U1 2 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13421 EP 13444 PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100014 ER PT J AU MOORE, HJ PLAUT, JJ SCHENK, PM HEAD, JW AF MOORE, HJ PLAUT, JJ SCHENK, PM HEAD, JW TI AN UNUSUAL VOLCANO ON VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MOUNT ST-HELENS; LAVA FLOWS; EFFUSION RATES; DOME; VISCOSITY; SURFACE; GROWTH; DYNAMICS; RHEOLOGY; MAGELLAN AB Materials that issued from an unusual Venusian volcano produced (1) a complex domical structure about 100 km across with thick, broad flow lobes up to 41 km wide, (2) an extensive sheet of thick flows, and (3) radar-bright surfaces that extend to 360400 km from the volcano. Altimetry indicates that the relief of the domical structure is about 0.5-1.1 km. The lobes and flows have prominent regularly spaced ridges approximately 686-820 m apart. Thick flows with large ridge separations and broad lobes are rare on Venus. We suggest that the viscosities these flows were larger than those of most lava flows on Venus. Comparisons of the dimensions of the volcano's lobes with lava flows on Earth suggest that the Venusian lavas may have large silica contents. Radar-bright surfaces around the volcano may represent the result of an explosive eruption or very thin deposits of low-viscosity lavas. Thus we suggest that the radar-bright surfaces and lavas of the volcano were derived from a magma that differentiated within the crust or mantle of Venus. The differentiation produced (1) a gas-rich low-viscosity phase, (2) high-viscosity lavas, and (3) a residual primary magma. C1 BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. JET PROP LAB,PASADENA,CA 91109. LUNAR & PLANETARY INST,HOUSTON,TX 77058. RP MOORE, HJ (reprint author), US GEOL SURVEY,MS 975,345 MIDDLEFIELD RD,MENLO PK,CA 94025, USA. NR 73 TC 28 Z9 28 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13479 EP 13493 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100016 ER PT J AU MCKENZIE, D FORD, PG JOHNSON, C PARSONS, B SANDWELL, D SAUNDERS, S SOLOMON, SC AF MCKENZIE, D FORD, PG JOHNSON, C PARSONS, B SANDWELL, D SAUNDERS, S SOLOMON, SC TI FEATURES ON VENUS GENERATED BY PLATE BOUNDARY PROCESSES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID TRANSFORM-FAULT ZONE; INITIAL ANALYSIS; APHRODITE TERRA; FRACTURE-ZONES; MAGELLAN; RIDGE; DEFORMATION; LITHOSPHERE; VOLCANISM; TECTONICS AB Various observations suggest that there are processes on Venus that produce features similar to those associated with plate boundaries on Earth. Synthetic aperture radar images of Venus, taken with a radar whose wavelength is 12.6 cm, are compared with GLORIA images of active plate boundaries, obtained with a sound source whose wavelength is 23 cm. Features similar to transform faults and to abyssal hills on slow and fast spreading ridges can be recognized within the Artemis region of Venus but are not clearly visible elsewhere. The composition of the basalts measured by the Venera 13 and 14 and the Vega 2 spacecraft corresponds to that expected from adiabatic decompression, like that which occurs beneath spreading ridges on Earth. Structures that resemble trenches are widespread on Venus and show the same curvature and asymmetry as they do on Earth. These observations suggest that the same simple geophysical models that have been so successfully used to understand the tectonics of Earth can also be applied to Venus. C1 UNIV OXFORD,DEPT EARTH SCI,OXFORD OX1 3PR,ENGLAND. JET PROP LAB,PASADENA,CA 91109. MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. INST THEORET GEOPHYS,DEPT EARTH SCI,CAMBRIDGE,ENGLAND. RI Parsons, Barry/K-4716-2012 NR 34 TC 52 Z9 52 U1 1 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13533 EP 13544 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100018 ER PT J AU BINDSCHADLER, DL DECHARON, A BERATAN, KK SMREKAR, SE HEAD, JW AF BINDSCHADLER, DL DECHARON, A BERATAN, KK SMREKAR, SE HEAD, JW TI MAGELLAN OBSERVATIONS OF ALPHA-REGIO - IMPLICATIONS FOR FORMATION OF COMPLEX RIDGED TERRAINS ON VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MANTLE FLOW TECTONICS; ISHTAR TERRA; RADAR; ORIGIN; REFLECTIVITY; PREDICTION; SURFACE; CRUST AB Magellan images of Alpha Regio reveal previously undetected structures and details of the morphology of this region of complex ridged terrain. We examine the complex ridged terrain of Alpha Regio, using morphology and crosscutting relationships between structures to derive a sequence of tectonic events. Structures include broad (approximately 10-20 km wide) linear and arcuate ridges, fine-scale (<3 km wide) ridges, linear disruption zones (LDZs) up to several kilometers wide, and numerous grabens (approximately 5 km wide) and associated scarps and troughs. Based on their morphology, we interpret the broad and fine-scale ridges as compressional structures, possibly folds. LDZs appear to be due to small amounts of lateral shear which most commonly disrupts the older ridge fabric. Graben and associated structures are interpreted as extensional features. They crosscut ridges and LDZs and thus appear to be the youngest structures in Alpha Regio. This sequence of events and information on the orientation of these various structures are compared to the predictions of two models for the formation of complex ridged terrain (and highlands on Venus in general): a hotspot model and a coldspot model. The presence of compressional features along and parallel to the margins of Alpha Regio and the lack of any high-elevation ring of extensional features are more consistent with a coldspot or roughly axisymmetric mantle downwelling. Mantle downwelling appears to be the most likely mode of formation of the upland of Alpha Regio and is likely to be important in other highland regions, such as Ovda and Thetis regiones, which are also dominated by complex ridged terrain. C1 JET PROP LAB,PASADENA,CA 91109. BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. RP BINDSCHADLER, DL (reprint author), UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,595 CIRCLE DR E,LOS ANGELES,CA 90024, USA. NR 36 TC 50 Z9 50 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13563 EP 13577 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100020 ER PT J AU SQUYRES, SW JANES, DM BAER, G BINDSCHADLER, DL SCHUBERT, G SHARPTON, VL STOFAN, ER AF SQUYRES, SW JANES, DM BAER, G BINDSCHADLER, DL SCHUBERT, G SHARPTON, VL STOFAN, ER TI THE MORPHOLOGY AND EVOLUTION OF CORONAE ON VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MAGELLAN AB Coronae on Venus are large, circular to ovoidal surface features that have distinctive tectonic, volcanic, and topographic expressions. They range in diameter from less than 200 km to at least 1000 km. New data from the Magellan spacecraft have shown coronae to be among the dominant tectonic forms on the planet and have revealed their morphology in unprecedented detail. Typical coronae are dominated by concentric tectonic features and have a raised rim, a central region higher than the surounding plains but in many instances lower than the rim, and, commonly, a peripheral depression or "moat". Some coronae also show significant amounts of radial tectonic structure, and in most cases this predates the concentric features. In addition, there are other features on Venus, recognized for the first time in Magellan data, that consist of domical rises with intense radial tectonic patterns and little or no concentric structure. All of these features commonly are associated with moderate to large quantities of volcanism. In fact, some radially fractured domes have undergone so much volcanism that volcanic construction appears to have played a significant role in establishing their topography. We explore a model of corona formation that links these forms into a genetic sequence. The model begins with the ascent of a mantle diapir. Upward mantle flow driven by its ascent forces the lithosphere above the diapir upward, producing a gentle dome with a radiating pattern of extensional fractures. As the diapir impinges on the underside of the lithsphere it flattens and spreads, transforming the uplift to a more flat-topped shape. In this flattened, near-surface configuration the diapir can cool rapidly. With the resultant loss of buoyancy the raised plateau can relax to form a central sag, a raised rim, and a depressed moat. Concentric tectonic features develop primarily during the latter stages of corona formation and hence are best preserved on mature coronae. Volcanism takes place during all phases of the uplift and may diminish as the relaxation occurs. Our analyses to date suggest that this scenario is broadly consistent with many of the coronae on Venus. However, there is enormous diversity in corona morphology, and features are present that require substantial deviations from this simple model. In particular, some circular depressions appear corona like in synthetic aperature radar images but may in fact be large calderas. Some of the variations observed in corona morphology may ultimately be interpretable in terms of variations in the behavior of individual diapirs and in the local properties of the Venusian lithosphere. C1 UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. LUNAR & PLANETARY INST,HOUSTON,TX 77058. JET PROP LAB,PASADENA,CA 91109. RP SQUYRES, SW (reprint author), CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853, USA. NR 21 TC 112 Z9 112 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13611 EP 13634 PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100023 ER PT J AU LEBERL, FW MAURICE, KE THOMAS, JK LEFF, CE WALL, SD AF LEBERL, FW MAURICE, KE THOMAS, JK LEFF, CE WALL, SD TI IMAGES AND TOPOGRAPHIC RELIEF AT THE NORTH-POLE OF VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MAGELLAN AB We report on the analysis of unique coverage of the north pole of Venus using a subset of 13 images from a total of about 775 synthetic aperture radar orbits during cycle 1 of the Magellan mission. We present images at 13 distinctly different azimuths that range over 360-degrees in longitude and that show the topographic relief at vastly different imaging geometries at intervals of about 20-degrees. A pair of intersecting or crossing orbits is used to assess the topographic relief with stereo radargrammetric techniques, and to refine this assessment using a multi-image clinometric approach. We show that the pole is located in accentuated topography with elevation differences in the range of no more than 1 km. We conclude that pinpointing the location of the pole from the overlapping images and standard mission data is accurate to within about 100 pixels or 8 km (RMS). C1 JET PROP LAB,PASADENA,CA 91109. RP LEBERL, FW (reprint author), VEXCEL CORP,2477 55TH ST,BOULDER,CO 80301, USA. NR 12 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1992 VL 97 IS E8 BP 13667 EP 13674 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JP211 UT WOS:A1992JP21100026 ER PT J AU WATSON, RT AF WATSON, RT TI THE BASICS OF THE GREENHOUSE-EFFECT SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,WASHINGTON,DC 20546. NR 0 TC 0 Z9 0 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 2 EP FUEL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ312 UT WOS:A1992JJ31201470 ER PT J AU BRYANT, RG AF BRYANT, RG TI POLYAZOMETHINES CONTAINING PENDENT TRIFLUOROMETHYL GROUPS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 47 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ313 UT WOS:A1992JJ31301259 ER PT J AU SMITH, JG CONNELL, JW HERGENROTHER, PM AF SMITH, JG CONNELL, JW HERGENROTHER, PM TI SYNTHESIS AND PROPERTIES OF POLY(ARYLENE ETHER)S CONTAINING PHENYL PHOSPHINE OXIDE SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 77 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ313 UT WOS:A1992JJ31301289 ER PT J AU HERGENROTHER, PM AF HERGENROTHER, PM TI HIGH-PERFORMANCE POLYMERS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 80 EP IEC PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ312 UT WOS:A1992JJ31201806 ER PT J AU MARDER, SR AF MARDER, SR TI MATERIALS CHEMISTRY ISSUES PERTAINING TO NONLINEAR OPTICS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 83 EP IEC PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ312 UT WOS:A1992JJ31201809 ER PT J AU MINTON, TK NELSON, CM MOORE, TA OKUMURA, M AF MINTON, TK NELSON, CM MOORE, TA OKUMURA, M TI A MOLECULAR-BEAM STUDY OF CHLORINE NITRATE PHOTOLYSIS AND ITS IMPLICATIONS FOR POLAR OZONE DEPLETION SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,DEPT CHEM,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. RI Okumura, Mitchio/I-3326-2013 OI Okumura, Mitchio/0000-0001-6874-1137 NR 0 TC 0 Z9 0 U1 1 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 93 EP PETR PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ313 UT WOS:A1992JJ31300658 ER PT J AU CHU, DA RUSSELL, JM CONNOR, BJ SCHEUER, C AF CHU, DA RUSSELL, JM CONNOR, BJ SCHEUER, C TI VALIDATION AND VARIABILITY OF ISAMS NO AND NO2 MEASUREMENTS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 GATS INC,HAMPTON,VA 23666. NASA,LANGLEY RES CTR,HAMPTON,VA 23666. SCI & TECHNOL CORP,HAMPTON,VA 23666. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 102 EP PETR PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ313 UT WOS:A1992JJ31300667 ER PT J AU NELSON, CM MOORE, TA MINTON, TK OKUMURA, M AF NELSON, CM MOORE, TA MINTON, TK OKUMURA, M TI PHOTODISSOCIATION DYNAMICS OF CL2O SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,DEPT CHEM & CHEM ENGN,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 139 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ313 UT WOS:A1992JJ31300808 ER PT J AU POWER, MB MACINNES, AN ZILLER, JW JENKINS, P HEPP, AF BARRON, AR AF POWER, MB MACINNES, AN ZILLER, JW JENKINS, P HEPP, AF BARRON, AR TI GALLIUM SULFIDO CLUSTERS - THEIR TOPOLOGICAL REORGANIZATION AND RELATIONSHIP TO NEW SOLID-STATE MATERIALS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. UNIV CALIF IRVINE,DEPT CHEM,IRVINE,CA 92717. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 153 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ312 UT WOS:A1992JJ31202004 ER PT J AU BEYENE, KW BU, X MASNOVI, J ANDRIST, AH HURWITZ, FI AF BEYENE, KW BU, X MASNOVI, J ANDRIST, AH HURWITZ, FI TI COLLISIONAL ACTIVATED DISSOCIATION SPECTRA OF ORGANOSILANES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 242 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ312 UT WOS:A1992JJ31202093 ER PT J AU JAFFE, RL SMITH, GD YOON, DY MCLEAN, AD AF JAFFE, RL SMITH, GD YOON, DY MCLEAN, AD TI QUANTUM-CHEMISTRY BASED POTENTIAL-ENERGY FUNCTIONS FOR SIMULATIONS OF POLYMER BLENDS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. ELORET INST,SUNNYVALE,CA 94087. IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 23 PY 1992 VL 204 BP 311 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA JJ313 UT WOS:A1992JJ31301507 ER PT J AU TINKER, ML CUTCHINS, MA AF TINKER, ML CUTCHINS, MA TI DAMPING PHENOMENA IN A WIRE ROPE VIBRATION ISOLATION SYSTEM SO JOURNAL OF SOUND AND VIBRATION LA English DT Article C1 AUBURN UNIV,DEPT AEROSP ENGN,AUBURN,AL 36849. RP TINKER, ML (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 21 TC 40 Z9 52 U1 1 U2 8 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD AUG 22 PY 1992 VL 157 IS 1 BP 7 EP 18 DI 10.1016/0022-460X(92)90564-E PG 12 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA JL391 UT WOS:A1992JL39100002 ER PT J AU SCHMIDLIN, FJ AF SCHMIDLIN, FJ TI 1ST OBSERVATION OF MESOPAUSE TEMPERATURES LOWER THAN 100-DEGREES-K SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Falling sphere measurements were part of a study to investigate the relationship between Noctilucent Clouds and Polar Mesospheric Summer Echoes within the context of interactions between the ionized and the neutral atmosphere. During this investigation there was one measurement of a very low mesopause temperature. This temperature is believed to be the lowest value ever observed in the terrestrial environment. The reasons why this cold mesopause measurement is considered to be valid are presented. RP SCHMIDLIN, FJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC,OBSERVAT SCI BRANCH,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337, USA. NR 8 TC 29 Z9 31 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 21 PY 1992 VL 19 IS 16 BP 1643 EP 1646 DI 10.1029/92GL01506 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JL393 UT WOS:A1992JL39300005 ER PT J AU THOMASON, LW OSBORN, MT AF THOMASON, LW OSBORN, MT TI LIDAR CONVERSION PARAMETERS DERIVED FROM SAGE-II EXTINCTION MEASUREMENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC AEROSOL; SIZE DISTRIBUTION; SATELLITE AB SAGE II multiwavelength aerosol extinction measurements are used to estimate mass- and extinction-to-backscatter conversion parameters. The basis of the analysis is the principal component analysis of the SAGE II extinction kernels to estimate both total aerosol mass and aerosol backscatter at a variety of wavelengths. Comparisons of coincident SAGE II extinction profiles with 0.694-mu-m aerosol backscatter profiles demonstrate the validity of the method. C1 SCI APPLICAT INT CORP,HAMPTON,VA 23666. RP THOMASON, LW (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 475,HAMPTON,VA 23665, USA. OI Thomason, Larry/0000-0002-1902-0840 NR 13 TC 40 Z9 41 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 21 PY 1992 VL 19 IS 16 BP 1655 EP 1658 DI 10.1029/92GL01619 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JL393 UT WOS:A1992JL39300008 ER PT J AU PUSECHEL, RF BLAKE, DF SNETSINGER, KG HANSEN, ADA VERMA, S KATO, K AF PUSECHEL, RF BLAKE, DF SNETSINGER, KG HANSEN, ADA VERMA, S KATO, K TI BLACK CARBON (SOOT) AEROSOL IN THE LOWER STRATOSPHERE AND UPPER TROPOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LIGHT-ABSORPTION; ARCTIC HAZE; EL-CHICHON; COMPONENT AB As determined by impactor samplers flown on ER-2 and DC-8 aircraft, black carbon aerosol (BCA) mass loadings in the stratosphere average 0.6 nanograms per standard cubic meter, or 0.01% of the total aerosol. Upper tropospheric BCA increases to 0.3%. Low stratospheric concentration is commensurate with present commercial air traffic fuel consumption, given the following assumptions: the BCA emissions are 0.1 grams per kilogram of fuel consumed, 10% of route mileage is above the tropopause, and average BCA stratospheric residence time is about one year. Taking BCA into account, the stratospheric single scatter albedo is almost-equal-to 0.99. Using parameters for planned supersonic commercial aircraft, whose emissions will be predominantly in the stratosphere, we show that such traffic will double stratospheric BCA concentration. This would reduce the aerosol single scattering albedo by one percent, and double the BCA surface area that is available for heterogeneous chemistry. C1 LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. SETI INST,MT VIEW,CA 94043. TMA NORCAL,RICHMOND,CA 94804. RP PUSECHEL, RF (reprint author), NASA,AMES RES CTR,MS 239-4,MOFFETT FIELD,CA 94035, USA. NR 26 TC 11 Z9 11 U1 2 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 21 PY 1992 VL 19 IS 16 BP 1659 EP 1662 DI 10.1029/92GL01801 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JL393 UT WOS:A1992JL39300009 ER PT J AU BURSIK, MI CAREY, SN SPARKS, RSJ AF BURSIK, MI CAREY, SN SPARKS, RSJ TI A GRAVITY CURRENT MODEL FOR THE MAY 18, 1980 MOUNT-ST-HELENS PLUME SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ERUPTION AB Observations of the stratospheric plume from the May 18, 1980, Mount St. Helens eruption suggest that it spread in the crosswind direction as an intrusive gravity current, as it was transported downwind. Grain size analyses of the plinian tephra are consistent with this model, suggesting that to distances of many hundreds of kilometers, turbulent atmospheric diffusion played a secondary role in plume spreading and tephra dispersal. C1 UNIV BRISTOL,DEPT GEOL,BRISTOL BS8 1RJ,ENGLAND. UNIV RHODE ISL,GRAD SCH OCEANOG,KINGSTON,RI 02881. JET PROP LAB,PASADENA,CA 91109. NR 21 TC 45 Z9 45 U1 0 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 21 PY 1992 VL 19 IS 16 BP 1663 EP 1666 DI 10.1029/92GL01639 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JL393 UT WOS:A1992JL39300010 ER PT J AU ALSOP, DC CHENG, ES CLAPP, AC COTTINGHAM, DA FISCHER, ML GUNDERSEN, JO KREYSA, E LANGE, AE LUBIN, PM MEINHOLD, PR RICHARDS, PL SMOOT, GF AF ALSOP, DC CHENG, ES CLAPP, AC COTTINGHAM, DA FISCHER, ML GUNDERSEN, JO KREYSA, E LANGE, AE LUBIN, PM MEINHOLD, PR RICHARDS, PL SMOOT, GF TI A SEARCH FOR ANISOTROPY IN THE COSMIC MICROWAVE BACKGROUND ON INTERMEDIATE ANGULAR SCALES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND ID RADIATION; FLUCTUATIONS AB The results of a search for anisotropy in the cosmic microwave background on angular scales near 1-degrees are presented. Observations were simultaneously performed in bands centered at frequencies of 6, 9, and 12 cm-1 with a multifrequency bolometric receiver mounted on a balloon-borne telescope. The statistical sensitivity of the data is the highest reported to date at this angular scale, which is of critical importance for understanding the formation of structure in the universe. Signals in excess of random were observed in the data. The experiment, data analysis, and interpretation are described. C1 UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF SANTA BARBARA,DEPT PHYS,SANTA BARBARA,CA 93106. MAX PLANCK INST RADIOASTRON,W-5300 BONN 1,GERMANY. LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. RI Alsop, David/J-5764-2013 OI Alsop, David/0000-0002-8206-1995 NR 17 TC 37 Z9 37 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1992 VL 395 IS 2 BP 317 EP 325 DI 10.1086/171654 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH628 UT WOS:A1992JH62800001 ER PT J AU TELESCO, CM GEZARI, DY AF TELESCO, CM GEZARI, DY TI HIGH-RESOLUTION 12.4 MICRON IMAGES OF THE STARBURST REGION IN M82 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (M82); GALAXIES, STARBURST; INFRARED, GALAXIES ID FAR-INFRARED SPECTROSCOPY; STAR-FORMATION; SUPERNOVA-REMNANTS; MOLECULAR CLOUDS; RADIO-SOURCES; SMALL GRAINS; GALAXY M82; EMISSION; NUCLEUS; DISCOVERY AB We present 12.4-mu-m images, made with 1" resolution, of the intense star-forming region in the galaxy M82. Considerable small-scale structure is evident, including several bright clumps less than approximately 20 pc in size which may be embedded with giant star clusters more massive than 3 x 10(5) M.. No correlation is seen between the infrared emission and the bright radio/X-ray point sources which are thought to be very young supernova remnants. We propose that high values of the ratio of nonthermal and infrared emission near the nucleus, and of the ratio L(IR)/L(CO) at one of the starburst lobes, can be attributed to disruption of the central region by supernova activity. However, we argue that the mid-infrared-emitting dust is heated by young stars and not, as recently proposed, by supernova shocks. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP TELESCO, CM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES63,HUNTSVILLE,AL 35812, USA. NR 40 TC 38 Z9 38 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1992 VL 395 IS 2 BP 461 EP & DI 10.1086/171665 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH628 UT WOS:A1992JH62800012 ER PT J AU GREENE, TP YOUNG, ET AF GREENE, TP YOUNG, ET TI NEAR-INFRARED OBSERVATIONS OF YOUNG STELLAR OBJECTS IN THE RHO-OPHIUCHI DARK CLOUD SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, INTERSTELLAR, CONTINUUM; ISM, INDIVIDUAL (RHO-OPHIUCHI); OPEN CLUSTERS AND ASSOCIATIONS, INDIVIDUAL (RHO-OPIUCHI); STARS, PRE-MAIN-SEQUENCE ID INITIAL MASS FUNCTION; IRAS OBSERVATIONS; SOLAR NEIGHBORHOOD; CLUSTER; EVOLUTION; COMPLEX; LUMINOSITY; DISCOVERY; DWARFS; BROWN AB We have conducted an imaging survey of 1.4 pc2 (650 arcmin2) of the rho-Ophiuchi dark cloud in the J, H, and K near-infrared photometric bands. Approximately 337 of our 481 detected sources are associated with the cloud, and we estimate that 48% of these have near-infrared excesses, indicative of disks or circumstellar material surrounding these young stellar objects (YSOs). The K-band luminosity function is significantly different in different regions of our survey area, suggesting that YSOs in these regions have different ages or mass functions. We estimate that the entire survey area has a high star-formation efficiency, SFE almost-equal-to 23%. Finally, our many newly detected sources provide a relatively large, uniformly sensitive sample of objects for study at longer wavelengths to better determine true source luminosities and evolutionary lifetimes. C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85724. RP GREENE, TP (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 35 TC 130 Z9 130 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1992 VL 395 IS 2 BP 516 EP 528 DI 10.1086/171672 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH628 UT WOS:A1992JH62800019 ER PT J AU SMALE, AP LOCHNER, JC AF SMALE, AP LOCHNER, JC TI LONG-TERM VARIABILITY IN LOW-MASS X-RAY BINARIES - A STUDY USING DATA FROM VELA-5B SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, CLOSE; STARS, VARIABLES, OTHER; X-RAYS, STARS ID TIME-SERIES ANALYSIS; UNEVENLY SPACED DATA; ORBITAL PERIOD; OPTICAL COUNTERPART; TRANSIENT V0332+53; CYGNUS X-2; 4U 1820-30; DISCOVERY; MODULATION; MODEL AB We have examined a complete sample of 1 s resolution Vela 5B data for all low-mass X-ray binaries for which they can be extracted without source confusion, and searched for periodicities of more than 1 day using Fourier analysis and period folding techniques. We confirm the existence of a 174.6 day period in X1820 - 303 with extremely high confidence, derive an accurate ephemeris for the modulation, and model the form of the folded light curve. We have searched the data from X1916 - 053 for the published 199 day period; no significant periodicities are detected in the raw data, although the candidate period appears in power spectra constructed from a filtered data set. We conclude that this period detection is not firm, with a false alarm probability (FAP) in the range 10% - 20%. For Cygnus X-2 we find a significant periodicity of 77.34 days with a false alarm probability of less than 10(-5); this may be associated with an accretion disk precession time scale. We detect the 4.8 hr orbital period of Cygnus X-3, and show in addition that the power spectrum shows variability on time scales up to 200 days. No periodicities greater than 1 day with a significance greater than 2-sigma were found in the following sources: NGC 1851, X0614 + 091, X0918 - 549, X0921 - 630, X1254 - 690, X1627 - 673, X1636 - 536, X1735 - 444, X1822 - 371, X1822 - 000, Serpens X-1, X1957 + 115, and M15. For these sources we have placed upper limits on the existence of periods of order hundreds of days, and also upon the detection of some periods in the literature of approximately a fev; days. Our analysis suggests that while long-term cyclic variability is common among high-mass binaries, it is a rare occurrence in the low-mass systems. C1 LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP SMALE, AP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. NR 53 TC 47 Z9 46 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1992 VL 395 IS 2 BP 582 EP 591 DI 10.1086/171678 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH628 UT WOS:A1992JH62800025 ER PT J AU HANNER, MS TOKUNAGA, AT GEBALLE, TR AF HANNER, MS TOKUNAGA, AT GEBALLE, TR TI THE 8-13 MICRON SPECTRUM OF THE YOUNG STELLAR OBJECT WL-16 SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; INFRARED, INTERSTELLAR, LINES; INFRARED, STARS; STARS, INDIVIDUAL (WL 16); STARS, PRE-MAIN-SEQUENCE ID POLYCYCLIC AROMATIC-HYDROCARBONS; OPHIUCHI DARK CLOUD; EMISSION FEATURES; IRAS OBSERVATIONS; CLUSTER; REGION; CORE AB Spectroscopy of WL 16 in the 8-13-mu-m region reveals a spectrum dominated by the hydrocarbon emission features at 7.7, 8.6, 11.25, and 12.7-mu-m. The emission plateau between the latter two features is detected, the first such detection in a young stellar object. The expected silicate feature is badly masked by the strong emission bands. Combining our spectra with the infrared spectral energy distribution indicates that silicate absorption is probably present. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. JOINT ASTRON CTR,HILO,HI 96720. RP HANNER, MS (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 25 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1992 VL 395 IS 2 BP L111 EP L113 DI 10.1086/186500 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH629 UT WOS:A1992JH62900014 ER PT J AU VEERARAGHAVAN, S STEBBINS, A AF VEERARAGHAVAN, S STEBBINS, A TI LARGE-SCALE MICROWAVE ANISOTROPY FROM GRAVITATING SEEDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY; COSMIC MICROWAVE BACKGROUND ID COSMIC STRINGS; GLOBAL TEXTURE; DOMAIN-WALLS AB Topological defects could have seeded primordial inhomogeneities in cosmological matter. We examine the horizon-scale matter and geometry perturbations generated by such seeds in an expanding homogeneous and isotropic universe. Evolving particle horizons generally lead to perturbations around motionless seeds, even when there are compensating initial underdensities in the matter. We describe the pattern of the resulting large angular scale microwave anisotropy. C1 NASA,CTR FERMILAB ASTROPHYS,FERMILAB,BATAVIA,IL 60510. RP VEERARAGHAVAN, S (reprint author), UNIV MASSACHUSETTS,DEPT PHYS & ASTRON,AMHERST,MA 01003, USA. NR 17 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1992 VL 395 IS 2 BP L55 EP L58 DI 10.1086/186487 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH629 UT WOS:A1992JH62900001 ER PT J AU WIELICKI, BA PARKER, L AF WIELICKI, BA PARKER, L TI ON THE DETERMINATION OF CLOUD COVER FROM SATELLITE SENSORS - THE EFFECT OF SENSOR SPATIAL-RESOLUTION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RADIATION BUDGET EXPERIMENT; THRESHOLD METHOD; FIELDS; EARTH; PARAMETERS; CLIMATE; IMAGERY; RAIN AB Landsat thematic mapper (TM) data are used to provide a very high spatial resolution source of cloud "truth." TM atmospheric window channels at wavelengths of 0.83 and 11.5-mu-m are used to simulate the visible and infrared channels on meteorological satellites. The TM data are spatially averaged to provide spatial resolutions (that is, pixel sizes) ranging from the full resolution 28.5-m data to the 1-, 4-, and 8-km resolutions typical of AVHRR and GOES data. These data are then used to examine the sensitivity of satellite-derived estimates of cloud fractional coverage to changing sensor spatial resolution. Seven different cloud retrieval algorithms are examined, including the International Satellite Cloud Climatology Project (ISCCP), new cloud for Earth (NCLE) radiation budget, hybrid bispectral threshold method (HBTM), spatial coherence, box counting based on fractal theory, reflectance threshold, and temperature threshold methods. The analysis is carried out for 24 cloud fields of varying cloud type: cumulus, stratocumulus, altocumulus, cirrus, and multilayered cloud. Results indicate that estimates of cloud fraction vary greatly as a function of sensor spatial resolution and cloud algorithm assumptions. Even for 28.5-m spatial resolution data, current cloud algorithms give cloud fractions that vary by as much as 0.25. In general, cloud algorithms are sensitive to either sensor resolution (threshold methods such as ISCCP or HBTM) or to assumptions about cloud optical depth (NCLE, spatial coherence). When present, the effect of sensor resolution is small for satellite pixel sizes less than 0.25 km. The effects are large for pixel sizes of 1 km or larger. Results are shown to be a strong function of cloud type. The effect of sensor resolution is strongest for boundary layer clouds and is very weak for cirrus clouds. At the 4- to 8-km spatial resolutions typical of meteorological satellite data, the ISCCP algorithm overestimates cloud fraction for boundary layer cloud by about 0.05 but underestimates thin cirrus by 0.05. The NCLE algorithm underestimates all cloud types by an average of 0.32, and spatial coherence underestimates boundary layer cloud fraction an average of 0. 18. For boundary layer clouds the errors are traced to the assumption of cloud-filled pixels for ISCCP, the assumption of optically thick clouds for spatial coherence, and the assumption of a typical cloud albedo for the NCLE method. Using 8-km data, the HBTM and ISCCP methods provide the most accurate cloud fraction, although the HBTM method underestimates thin cirrus by 0.20 and ISCCP overestimates all cloud types but cirrus by about 0.05. The 24 cloud fields examined were chosen to explore some of the more difficult cloud retrieval cases, so the results should not be extrapolated to global average conditions. Nevertheless, the results suggest a critical need for a clearer understanding of the performance of satellite-derived cloud properties. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP WIELICKI, BA (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 40 TC 134 Z9 135 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1992 VL 97 IS D12 BP 12799 EP 12823 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL282 UT WOS:A1992JL28200003 ER PT J AU BESS, TD SMITH, GL CHARLOCK, TP ROSE, FG AF BESS, TD SMITH, GL CHARLOCK, TP ROSE, FG TI ANNUAL AND INTERANNUAL VARIATIONS OF EARTH-EMITTED RADIATION BASED ON A 10-YEAR DATA SET SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OUTGOING LONGWAVE RADIATION; SOUTHERN-HEMISPHERE; ANNUAL CYCLE; TROPICAL PACIFIC; BUDGET; OSCILLATION; HISTORY; OCEAN AB Earth-emitted radiation varies in space and time due to variations of atmospheric and surface temperature, clouds, and water vapor. The method of empirical orthogonal functions (EOFs) has been applied to a 10-year data set of outgoing longwave radiation to study this variability. Spherical harmonic functions are used as a basis set for producing equal area map results. The following findings are noted. The first EOF accounts for 66% of the variance. After that, each EOF accounts for only a small variance, forming a slowly converging series. The first two EOFs describe mainly the annual cycle. The third EOF is primarily the semiannual cycle, although many other EOFs also contain significant semiannual parts. These results reaffirm earlier studies based on a shorter data set. In addition, a much stronger spring/fall mode was found in the central equatorial Pacific Ocean for the second EOF than had been found earlier. This difference is attributed to the use of broadband radiometer data which were available for the present study. The earlier study used data from a window-channel instrument which is not as sensitive to water vapor variations. The fourth EOF describes much of the 1976-1977 and 1982-1983 ENSO phenomena. There is typically a gap in the spectrum between a semiannual peak and the annual cycle for all but the first EOF. A semiannual dipole straddles the Asian-Australian monsoon track. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP BESS, TD (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 31 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1992 VL 97 IS D12 BP 12825 EP 12835 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL282 UT WOS:A1992JL28200004 ER PT J AU CROS, B NGANGA, D MINGA, A FISHMAN, J BRACKETT, V AF CROS, B NGANGA, D MINGA, A FISHMAN, J BRACKETT, V TI DISTRIBUTION OF TROPOSPHERIC OZONE AT BRAZZAVILLE, CONGO, DETERMINED FROM OZONESONDE MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CARBON-MONOXIDE; BRAZIL; POLLUTION; SEASON AB An analysis of 33 ozonesonde launches in Brazzaville, Congo (4-degrees-S, 15-degrees-E), between June 1990 and May 1991 is presented. The data indicate highest tropospheric amounts between June and early October, coincident with the dry season and with the presence of enhanced widespread biomass burning. The seasonal cycle of ozone derived from the ozonesonde measurements is in good agreement with the climatological seasonal cycle inferred from the use of satellite data and both seasonal cycles peak in September. Averaged throughout the year, the integrated amount of ozone derived from the ozonesondes is 44 Dobson units (DU) and is 39 DU using the satellite data. Within the troposphere the highest partial pressures are generally found at pressure levels near 700 mbar (approximately 3 km). Using simultaneous ozonesonde data from Ascension Island (8-degrees-S, 15-degrees-W), examples are presented illustrating that differences in the troposphere are primarily responsible for the observed spatial gradients of total ozone observed by TOMS. Calculation of correlation coefficients suggests that total ozone measurements may be a better indicator of the amount of ozone in the troposphere than are surface measurements. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. RP CROS, B (reprint author), UNIV MAIEN NGOUABI, FAC SCI, DEPT PHYS, PHYS ATMOSPHERE LAB, BRAZZAVILLE, CONGO PEOPL REP. NR 21 TC 44 Z9 44 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 AUG 20 PY 1992 VL 97 IS D12 BP 12869 EP 12875 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL282 UT WOS:A1992JL28200008 ER PT J AU BLAKESLEE, RJ KRIDER, EP AF BLAKESLEE, RJ KRIDER, EP TI GROUND-LEVEL MEASUREMENTS OF AIR CONDUCTIVITIES UNDER FLORIDA THUNDERSTORMS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID THUNDERCLOUDS; CURRENTS; CORONAE AB Values of the positive and negative polar conductivities under summer thunderstorms in Florida are highly variable and exhibit a significant electrode effect, but the total conductivity usually remains close to values found in fair weather, 0.4 to 1.8x10(-14) S/m. With these values a method proposed by Krider and Musser in 1982 for estimating the total conductivity from changes in the slope of the electric field recovery following a lightning discharge will be extremely sensitive to small time variations in the local Maxwell current density and must be modified to include these effects. C1 UNIV ARIZONA, INST ATMOSPHER PHYS, TUCSON, AZ 85721 USA. RP BLAKESLEE, RJ (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. NR 20 TC 6 Z9 6 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1992 VL 97 IS D12 BP 12947 EP 12951 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL282 UT WOS:A1992JL28200015 ER PT J AU POLLOCK, WH HEIDT, LE LUEB, RA VEDDER, JF MILLS, MJ SOLOMON, S AF POLLOCK, WH HEIDT, LE LUEB, RA VEDDER, JF MILLS, MJ SOLOMON, S TI ON THE AGE OF STRATOSPHERIC AIR AND OZONE DEPLETION POTENTIALS IN POLAR-REGIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID 72-DEGREES-S LATITUDE; INSITU OBSERVATIONS; ARCTIC VORTEX; 54-DEGREES-S; ATMOSPHERE; ANTARCTICA; WINTER; BRO AB Observations of the nearly inert, man-made chlorofluorocarbon CFC-1 15 obtained during January 1989 are used to infer the age of air in the lower stratosphere. These observations together with estimated release rates suggest an average age of high-latitude air at pressure altitudes near 17-21 km of about 3 to 5 years. This information is used together with direct measurements of HCFC-22, HCFC-142b, CH3Br, H-1301, H-1211, and H-2402 to examine the fractional dissociation of these species within the Arctic polar lower stratosphere compared to that of CFC-11 and hence to estimate their local ozone depletion potentials in this region. It is shown that these HCFCs are much less efficiently dissociated within the stratosphere than CFC-11, lowering their ozone depletion potentials to only about 30-40% of their chlorine loading potentials. In contrast, the observations of CH3Br and the Halons considered here confirm that they are rapidly dissociated within the stratosphere, with important implications for their ozone depletion potentials. C1 UNIV COLORADO, NOAA, COOPERAT INST RES ENVIRONM SCI, BOULDER, CO 80309 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP POLLOCK, WH (reprint author), NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. RI Mills, Michael/B-5068-2010 OI Mills, Michael/0000-0002-8054-1346 NR 20 TC 41 Z9 41 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 AUG 20 PY 1992 VL 97 IS D12 BP 12993 EP 12999 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL282 UT WOS:A1992JL28200018 ER PT J AU REMSBERG, EE BHATT, PP MILES, T AF REMSBERG, EE BHATT, PP MILES, T TI A COMPARISON OF NIMBUS-7 LIMB INFRARED MONITOR OF THE STRATOSPHERE AND RADIOSONDE TEMPERATURES IN THE LOWER STRATOSPHERE POLEWARD OF 60N SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID VALIDATION; RETRIEVALS; ACCURACY; OZONE AB Discrepancies have been noted in the literature between distributions of HNO3 and NO2 from Nimbus 7 limb infrared monitor of the stratosphere (LIMS) and from gas-phase model calculations, particularly in polar winter. The inclusion of heterogeneous chemistry processes into models gives improved agreement for HNO3 but not for NO2. For this reason we considered whether there were temperature bias errors for LIMS that would have an impact on its species retrievals in polar regions. The 7 months of Nimbus 7 LIMS mapped temperatures are compared with daily, lower stratospheric radiosonde (RAOB) observations at 1200 UTC from a set of 22 stations poleward of 60N. The 7-month average LIMS minus RAOB differences for the set are within +/- 0.3 K at 30, 50, and 70 hPa; LIMS minus RAOB equals -1.2 K +/- 2.2 K at 100 hPa. Springtime comparisons at 30 hPa were improved after recommended solar corrections were applied to the subset of daylight RAOB temperatures. Time series comparisons were conducted at 10 hPa for four stations in the Aleutian sector. After a correction for radiative cooling was applied to the RAOB data, the LIMS minus RAOB differences at 10 hPa were within +/- 2 K, except in winter when LIMS was still significantly warmer by several degrees. Much of that bias is attributed to spatial temperature variations for LIMS/RAOB comparisons in regions of temperature extremes and to the finite vertical resolution of LIMS. All of this means that there is almost no significant error in the LIMS temperatures that could impact the accuracy of LIMS constituent retrievals throughout much of the polar lower stratosphere. The LIMS cold bias at 100 hPa is most pronounced for the 22 station set in November and December (about -1.9 K) and is statistically significant for many of the stations. LIMS tends to smooth through the vertical structure associated with elevated warm layers near 100 hPa. This negative temperature bias leads to retrieved overestimates of LIMS species concentrations below about the 70-hPa level. C1 HUGHES STX CORP, HAMPTON, VA 23666 USA. HUGHES STX, LANHAM, MD 20706 USA. RP REMSBERG, EE (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NR 37 TC 8 Z9 8 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 AUG 20 PY 1992 VL 97 IS D12 BP 13001 EP 13014 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL282 UT WOS:A1992JL28200019 ER PT J AU TORRES, O AHMAD, Z HERMAN, JR AF TORRES, O AHMAD, Z HERMAN, JR TI OPTICAL EFFECTS OF POLAR STRATOSPHERIC CLOUDS ON THE RETRIEVAL OF TOMS TOTAL OZONE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ARCTIC STRATOSPHERE; LIDAR OBSERVATIONS; SEPTEMBER 1987; SAM-II; HOLE; ULTRAVIOLET; ANTARCTICA; ATMOSPHERE; AEROSOL; VORTEX AB Small areas of sharply reduced ozone density appear frequently in the maps produced from polar region total ozone mapping spectrometer (TOMS) data. These mini-holes are of the order of 1000 km in extent with a lifetime of a few days. On the basis of measurements from ground-based instruments, balloon-borne ozonesondes, and simultaneous measurements of aerosol and ozone concentrations during aircraft flights in the Arctic and Antarctic regions, the appearance of polar stratospheric clouds (PSCs) are frequently associated with false reductions in ozone derived from the TOMS albedo data. By combining radiative transfer calculations with the observed PSC and ozone data, it is shown that PSCs located near or above the ozone density maximum (with optical thickness greater than 0. 1) can explain most of the differences between TOMS ozone data and ground or in situ ozone measurements. Several examples of real and false TOMS mini-hole phenomenon are investigated using data from the 1989 Airborne Arctic Stratospheric Expedition (AASE) and from balloon flights over Norway and Sweden. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP TORRES, O (reprint author), HUGHES STX CORP, LANHAM, MD 20706 USA. RI Torres, Omar/G-4929-2013 NR 34 TC 10 Z9 10 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1992 VL 97 IS D12 BP 13015 EP 13024 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL282 UT WOS:A1992JL28200020 ER PT J AU KONDO, Y AIMEDIEU, P KOIKE, M IWASAKA, Y NEWMAN, PA SCHMIDT, U MATTHEWS, WA HAYASHI, M SHELDON, WR AF KONDO, Y AIMEDIEU, P KOIKE, M IWASAKA, Y NEWMAN, PA SCHMIDT, U MATTHEWS, WA HAYASHI, M SHELDON, WR TI REACTIVE NITROGEN, OZONE, AND NITRATE AEROSOLS OBSERVED IN THE ARCTIC STRATOSPHERE IN JANUARY 1990 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NITRIC-ACID; ANTARCTIC STRATOSPHERE; BALLOON OBSERVATIONS; POLAR STRATOSPHERE; HETEROGENEOUS REACTIONS; HYDROGEN-CHLORIDE; AIRBORNE LIDAR; ODD-NITROGEN; WATER-VAPOR; PARTICLES AB Total reactive nitrogen (NOy), nitrate aerosols, and ozone were measured between 12 and 30 km on board balloons launched from Esrange, near Kiruna, Sweden (68-degrees-N, 20-degrees-E), on January 18 and 31, 1990. A series of ozone measurements were performed using small balloons in addition to the measurements made simultaneously with NOy on the large gondola. On January 18, Kiruna was located inside the polar vortex, while it was outside the vortex on January 31. The NOy mixing ratio inside the vortex was 5 +/- 1 parts per billion by volume (ppbv) at the altitudes between 20 and 22 km. This value is considerably smaller than the value of about 13 ppbv that is expected from gas phase chemistry, indicating that a degree of denitrification had occurred by mid-January in 1990. On the other hand, the NOy mixing ratio outside the vortex in the same altitude region ranged between 6 and 13 ppbv, suggesting less denitrification outside the vortex. The cause of the denitrification is interpreted in terms of the very cold stratospheric temperature that prevailed from December 1989 to January 1990. The mixing ratios of nitric acid in gas phase (Schlager et al., 1990) and particulate phase (Hofmann et al., 1990) were measured on January 31, but not on the same gondola. The HNO3/NOy ratio was close to unity in a polar stratospheric cloud but decreased to 0.75 +/- 0.05 outside the cloud. Assuming this ratio, HNO3 has been found to be highly supersaturated over nitric acid trihydrate particles. C1 CNRS, F-91371 VERRIERES LE BUISSON, FRANCE. DSIR, CENTRAL OTAGO 9182, NEW ZEALAND. FORSCHUNGSZENTRUM JULICH, INST CHEM & DYNAM GEOSPHERE, W-5170 JULICH, GERMANY. UNIV HOUSTON, DEPT PHYS, HOUSTON, TX 77204 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP KONDO, Y (reprint author), NAGOYA UNIV, SOLAR TERR ENVIRONM LAB, TOYOKAWA, AICHI 442, JAPAN. RI Koike, Makoto/F-4366-2011; Kondo, Yutaka/D-1459-2012; Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 47 TC 18 Z9 18 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 AUG 20 PY 1992 VL 97 IS D12 BP 13025 EP 13038 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JL282 UT WOS:A1992JL28200021 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H SHEEHY, JA LANGHOFF, SR ROSI, M AF BAUSCHLICHER, CW PARTRIDGE, H SHEEHY, JA LANGHOFF, SR ROSI, M TI THEORETICAL-STUDY OF THE BONDING OF THE 1ST-ROW AND 2ND-ROW TRANSITION-METAL POSITIVE-IONS TO METHYLENE SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN-BASIS SETS; GAS-PHASE PHOTODISSOCIATION; MOLECULAR CALCULATIONS; DISSOCIATION-ENERGIES; GEOMETRIC STRUCTURES; ELECTRON CORRELATION; PERIODIC TRENDS; STATES; ATOMS; CH2 AB The geometries of the molecules formed by the interaction of the first- and second-row transition-metal cations with methylene are optimized at the modified coupled-pair functional (MCPF) level of theory using large Gaussian basis sets, and their dissociation energies are computed employing both the MCPF and internally contracted averaged coupled-pair functional (ICACPF) methods. The computed binding energies are generally in good agreement with the available experimental results, although the calculations indicate that the experimental values for ScCH2+, TiCH2+, and NbCH2+ are probably too large. The nature of the bonding in each case and trends in the bonding patterns across the transition-metal rows are discussed. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Rosi, Marzio/L-5748-2015 OI Rosi, Marzio/0000-0002-1264-3877 NR 37 TC 95 Z9 95 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD AUG 20 PY 1992 VL 96 IS 17 BP 6969 EP 6973 DI 10.1021/j100196a022 PG 5 WC Chemistry, Physical SC Chemistry GA JK807 UT WOS:A1992JK80700022 ER PT J AU FAHAY, MP AF FAHAY, MP TI DEVELOPMENT AND DISTRIBUTION OF CUSK EEL EGGS AND LARVAE IN THE MIDDLE ATLANTIC BIGHT WITH A DESCRIPTION OF OPHIDION-ROBINSI N-SP (TELEOSTEI, OPHIDIIDAE) SO COPEIA LA English DT Article ID FISHES AB The Ophidiidae was the seventh most abundant family represented in ichthyo-plankton collections in the Middle Atlantic Bight from 1977 through 1987. Seven distinct larvae occurred: most abundant were Lepophidium profundorum, Ophidion marginatum and Ophidion robinsi n. sp., but O. selenops, O. holbrooki, O. welshi and Otophidium omostigmum were also collected. Examination of ontogenetic development of the three most abundant species and congeners in the Gulf of Mexico revealed differences between Lepophidium and Ophidion. In Lepophidium, vertebrae ossify from anterior to posterior, pectoral-fin rays form early, and cartilaginous epurals appear in larvae. In Ophidion, vertebrae form from both ends toward the middle, pectoral-fin rays form late, and there are no epurals. In both genera, the extreme anterior position of the pelvic-fin rays, and swim-bladder structures associated with sound production develop in stages older than pelagic larvae. Lepophidium profundorum larvae were primarily distributed over the outer half of the continental shelf, as far north as the southern flank of Georges Bank during summer. In the laboratory, O. marginatum spawned nightly for 2 mo, each female releasing a single mucilaginous sac containing a small batch of eggs. Larvae were distributed nearshore from Block Island Sound to Cape Hatteras during the summer. Larvae of O. robinsi, recognized by low numbers of meristic characters and distinct pigment and body proportions, occurred during spring and summer, and were common over midshelf depths between Cape Hatteras and the New York Bight. Meristic characters separate O. robinsi n. sp. from two other prominently spotted ophidiines, O. grayi and Otophidium omostigmum. RP FAHAY, MP (reprint author), NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 25 TC 14 Z9 15 U1 0 U2 2 PU AMER SOC ICHTHYOLOGISTS HERPETOLOGISTS BUSINESS OFFICE PI CARBONDALE PA SOUTHERN ILLINOIS UNIV, DEPT ZOOLOGY, CARBONDALE, IL 62901-6501 SN 0045-8511 J9 COPEIA JI Copeia PD AUG 18 PY 1992 IS 3 BP 799 EP 819 DI 10.2307/1446157 PG 21 WC Zoology SC Zoology GA JK201 UT WOS:A1992JK20100020 ER PT J AU BOSELA, PA SHAKER, FJ FERTIS, DG AF BOSELA, PA SHAKER, FJ FERTIS, DG TI DYNAMIC ANALYSIS OF SPACE-RELATED LINEAR AND NONLINEAR STRUCTURES SO COMPUTERS & STRUCTURES LA English DT Note AB In order to be cost-effective, space structures must be extremely light-weight, and subsequently, very flexible structures, The power system for Space Station 'Freedom' is such a structure. Each array consists of a deployable truss mast and a split 'blanket' of photo-voltaic solar collectors. The solar arrays are deployed in orbit, and the blanket is stretched into position as the mast is extended. Geometric stiffness due to the preload make this an interesting non-linear problem. The space station will be subjected to various dynamic loads, during shuttle docking, solar tracking, attitude adjustment, etc. Accurate prediction of the natural frequencies and mode shapes of the space station components, including the solar arrays, is critical for determining the structural adequacy of the components, and for designing a dynamic controls system. This paper chronicles the process used in developing and verifying the finite element dynamic model of the photo-voltaic arrays. Various problems were identified in the investigation, such as grounding effects due to geometric stiffness, large displacement effects, and pseudo-stiffness (grounding) due to lack of required rigid body modes. Various analysis techniques, such as development of rigorous solutions using continuum mechanics, finite element solution sequence altering, equivalent systems using a curvature basis, Craig-Bampton superelement approach, and modal ordering schemes were utilized. This paper emphasizes the grounding problems associated with the geometric stiffness. C1 UNIV AKRON,DEPT CIVIL ENGN,AKRON,OH 44325. NASA,LEWIS RES CTR,STRUCT SYST DYNAM BRANCH,CLEVELAND,OH 44135. RP BOSELA, PA (reprint author), CLEVELAND STATE UNIV,DEPT ENGN TECHNOL,CLEVELAND,OH 44115, USA. NR 11 TC 2 Z9 2 U1 2 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD AUG 17 PY 1992 VL 44 IS 5 BP 1145 EP 1148 DI 10.1016/0045-7949(92)90335-W PG 4 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA JM702 UT WOS:A1992JM70200018 ER PT J AU STEINTHORSSON, E SHIH, TIP ROELKE, RJ AF STEINTHORSSON, E SHIH, TIP ROELKE, RJ TI ENHANCING CONTROL OF GRID DISTRIBUTION IN ALGEBRAIC GRID GENERATION SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE GRID GENERATION; TRANSFINITE INTERPOLATION; STRETCHING FUNCTIONS; BLENDING FUNCTIONS AB Three techniques are presented to enhance the control of grid-point distribution for a class of algebraic grid generation methods known as the two-, four- and six-boundary methods. First, multidimensional stretching functions are presented, and a technique is devised to construct them based on the desired distribution of grid points along certain boundaries. Second, a normalization procedure is proposed which allows more effective control over orthogonality of grid lines at boundaries and curvature of grid lines near boundaries. And third, interpolating functions based on tension splines are introduced to control curvature of grid lines in the interior of the spatial domain. In addition to these three techniques, consistency conditions are derived which must be satisfied by all user-specified data employed in the grid generation process to control grid-point distribution. The usefulness of the techniques developed in this study was demonstrated by using them in conjunction with the two- and four-boundary methods to generate several grid systems, including a three-dimensional grid system in the coolant passage of a radial turbine blade with serpentine channels and pin fins. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP STEINTHORSSON, E (reprint author), CARNEGIE MELLON UNIV,DEPT MECH ENGN,PITTSBURGH,PA 15213, USA. NR 4 TC 6 Z9 6 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD AUG 15 PY 1992 VL 15 IS 3 BP 297 EP 311 DI 10.1002/fld.1650150304 PG 15 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA JG305 UT WOS:A1992JG30500003 ER PT J AU SALEM, JA CHOI, SR FREEDMAN, MR JENKINS, MG AF SALEM, JA CHOI, SR FREEDMAN, MR JENKINS, MG TI MECHANICAL-BEHAVIOR AND FAILURE PHENOMENON OF AN INSITU TOUGHENED SILICON-NITRIDE SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID FRACTURE-TOUGHNESS; STRENGTH AB The Weibull modulus, fracture toughness and crack-growth resistance of an in situ toughened, silicon nitride material used to manufacture a turbine combustor were determined from room temperature to 1371-degrees-C. The material exhibited an elongated grain structure that resulted in improved fracture toughness, non-linear crack-growth resistance, and good elevated-temperature strength. However, low-temperature strength was limited by grains of excessive length (30-100-mu-m), These excessively long grains were surrounded by regions rich in sintering additives. C1 OAK RIDGE NATL LAB,OAK RIDGE,TN. RP SALEM, JA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 18 TC 16 Z9 16 U1 1 U2 5 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD AUG 15 PY 1992 VL 27 IS 16 BP 4421 EP 4428 DI 10.1007/BF00541575 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA JJ210 UT WOS:A1992JJ21000024 ER PT J AU TAKANO, Y LIOU, KN MINNIS, P AF TAKANO, Y LIOU, KN MINNIS, P TI THE EFFECTS OF SMALL ICE CRYSTALS ON CIRRUS INFRARED RADIATIVE PROPERTIES SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CLOUDS; SCATTERING; PARTICLES AB Using a model that combines single-scattering properties for spheroidal and hexagonal ice crystals. the thermal infrared radiative properties of cirrus clouds have been investigated. Infrared scattering and absorption properties for randomly oriented spheroids and hexagons are parameterized based on the anomalous diffraction theory and a geometric rav-tracing method, respectively. Using observed ice crystal size distributions, upwelling radiances at the top of cirrus cloudy atmospheres have been computed. Results show that the presence of small ice crystals can produce significant brightness temperature differences between two infrared wavelengths in the 10-mu-m window. Theoretical results have been compared with observed brightness temperature differences between 8.35 and 11.16-mu-m and between 11.16 and 12-mu-m. The observed values were obtained from the High-Spectral Resolution Interferometer Sounder. It is shown that the use of the present nonspherical model for ice crystals in radiative transfer calculations leads to a significantly better interpretation of the observed data than does the use of the spherical model. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP TAKANO, Y (reprint author), UNIV UTAH,CARSS,DEPT METEOROL,809 WM C BROWNING BLDG,SALT LAKE CITY,UT 84112, USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 12 TC 73 Z9 74 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 1992 VL 49 IS 16 BP 1487 EP 1493 DI 10.1175/1520-0469(1992)049<1487:TEOSIC>2.0.CO;2 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JG889 UT WOS:A1992JG88900007 ER PT J AU SUAREZ, MJ DUFFY, DG AF SUAREZ, MJ DUFFY, DG TI TERRESTRIAL SUPERROTATION - A BIFURCATION OF THE GENERAL-CIRCULATION SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID SHALLOW-WATER EQUATIONS AB When sufficiently large zonally asymmetric tropical heating is introduced in a two-level model of global atmospheric flow, its general circulation becomes strongly superrotating. The nature of the superrotating solutions is studied by examining momentum and heat budgets for a range of values of thermal forcing. Changes in the transport of zonal momentum by transient eddies appear to play the kev role in the transition to superrotation. The dramatic bifurcation of the solutions of this model may help explain the maintenance and variability of the zonal mean flow in the tropics. RP SUAREZ, MJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 14 TC 49 Z9 49 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 1992 VL 49 IS 16 BP 1541 EP 1554 DI 10.1175/1520-0469(1992)049<1541:TSABOT>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JG889 UT WOS:A1992JG88900011 ER PT J AU HARLAFTIS, ET HASSALL, BJM NAYLOR, T CHARLES, PA SONNEBORN, G AF HARLAFTIS, ET HASSALL, BJM NAYLOR, T CHARLES, PA SONNEBORN, G TI UV SPECTROSCOPY OF Z CHAMAELEONTIS .1. TIME-DEPENDENT DIPS IN SUPEROUTBURST SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE BINARIES, CLOSE; STARS, INDIVIDUAL, Z-CHA; NOVAE, CATACLYSMIC VARIABLES; ULTRAVIOLET, STARS ID NOVA OY CARINAE; X-RAY-EMISSION; Z-CHA; ACCRETION DISKS; DWARF NOVAE; IUE ARCHIVE; VW HYDRI; OUTBURST; PHOTOMETRY; CALIBRATION AB We present extensive IUE observations of the dwarf nova Z Cha during the 1987 April superoutburst, and IUE-EXOSAT observations during the 1985 July superoutburst. The UV light curve shows two dips when folded on the orbital period. One dip, at orbital phase 0.8, becomes shallower as the superoutburst progresses and can be associated with decreasing mass transfer rate from the secondary star. The other dip, at orbital phase 0.15, appears after the development of the superhump and some days after the occurrence of the largest dip at phase 0.8. The continuum flux distribution during superoutbursts is fainter and redder than in low-inclination dwarf novae during superoutbursts. We interpret this in terms of an extended vertical disc structure which occults the hot inner parts of the disc with the development of a 'cool' bulge on the edge of the disc at orbital phase 0.75. Details of the behaviour of the UV emission lines during eclipse and away from eclipse are discussed. In contrast to OY Car, we derive only an upper limit to the soft X-ray flux of Z Cha which could be caused by an interstellar column N(H) in the range 2 x 10(18)-9 X 10(20) cm-2. C1 ROYAL GREENWICH OBSERV,CAMBRIDGE CB3 0EZ,ENGLAND. ROYAL GREENWICH OBSERV,E-38780 ST CRUZ LA PALMA,SPAIN. UNIV CAMBRIDGE,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HARLAFTIS, ET (reprint author), NUCL PHYS LAB,DEPT ASTROPHYS,KEBLE RD,OXFORD OX1 3RH,ENGLAND. RI Sonneborn, George/D-5255-2012; Naylor, Tim /A-9465-2015 NR 50 TC 19 Z9 20 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 15 PY 1992 VL 257 IS 4 BP 607 EP 619 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH512 UT WOS:A1992JH51200006 ER PT J AU DOWKER, HF HALLIWELL, JJ AF DOWKER, HF HALLIWELL, JJ TI QUANTUM-MECHANICS OF HISTORY - THE DECOHERENCE FUNCTIONAL IN QUANTUM-MECHANICS SO PHYSICAL REVIEW D LA English DT Article ID WIGNER FUNCTION; CONSISTENT HISTORIES; BROWNIAN-MOTION; WAVE PACKET; COSMOLOGY; SPACETIME; ENVIRONMENT; PRINCIPLE; UNIVERSE; MODEL AB We study a formulation of quantum mechanics in which the central notion is that of a quantum-mechanical history-a sequence of events at a succession of times. The primary aim is to identify sets of "decoherent" (or "consistent") histories for the system. These are quantum-mechanical histories suffering negligible interference with each other, and, therefore, to which probabilities may be assigned. These histories may be found for a given system using the so-called decoherence functional. When the decoherence functional is exactly diagonal, probabilities may be assigned to the histories, and all probability sum rules are satisfied exactly. We propose a condition for approximate decoherence, and argue that it implies that most probability sum rules will be satisfied to approximately the same degree. We also derive an inequality bounding the size of the off-diagonal terms of the decoherence functional. We calculate the decoherence functional for some simple one-dimensional systems, with a variety of initial states. For these systems, we explore the extent to which decoherence is produced using two different types of coarse graining. The first type of coarse graining involves imprecise specification of the particle's. position. The second involves coupling the particle to a thermal bath of harmonic oscillators and ignoring the details of the bath (the Caldeira-Leggett model). We argue that both types of coarse graining are necessary in general. We explicitly exhibit the degree of decoherence as a function of the temperature of the bath, and of the width to within which the particle's position is specified. We study the diagonal elements of the decoherence functional, representing the probabilities for the possible histories of the system. To the extent that the histories decohere, we show that the probability distributions are peaked about the classical histories of the system, with the distribution of their initial positions and momenta given by a smeared version of the Wigner function. We discuss this result in connection with earlier uses of the Wigner function in this context. We find that there is a certain amount of tension between the demands of decoherence and peaking about classical paths. C1 MIT, CTR THEORET PHYS, NUCL SCI LAB, CAMBRIDGE, MA 02139 USA. RP NASA, CTR FERMILAB ASTROPHYS, FERMI NATL ACCELERATOR LAB, POB 500, BATAVIA, IL 60510 USA. NR 50 TC 129 Z9 129 U1 1 U2 7 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD AUG 15 PY 1992 VL 46 IS 4 BP 1580 EP 1609 DI 10.1103/PhysRevD.46.1580 PG 30 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA JH749 UT WOS:A1992JH74900032 ER PT J AU FAN, Y FINN, JE MONSON, PA AF FAN, Y FINN, JE MONSON, PA TI MONTE-CARLO SIMULATIONS OF ADSORPTION EQUILIBRIA AT STATES NEAR BULK FLUID PHASE BOUNDARIES SO FLUID PHASE EQUILIBRIA LA English DT Article DE ADSORPTION; WETTING; MONTE-CARLO SIMULATION; INTERFACES; DENSITY FUNCTIONAL THEORY; PREWETTING ID DENSITY-FUNCTIONAL-THEORY; WETTING TRANSITIONS; COMPUTER-SIMULATION; WALL INTERFACE; MULTILAYER ADSORPTION; DRYING TRANSITIONS; CONTACT-ANGLE; SUM-RULES; ENSEMBLE; WATER AB We discuss the use of Monte Carlo simulations to study adsorption on solid surfaces from fluids and fluid mixtures at states near to coexistence boundaries of the bulk fluid. The work is focused primarily upon the relationship between the adsorption isotherms and the nature of the contact between the coexisting fluid phases and the solid surface, and the behavior associated with the occurrence of wetting transitions in the system. Previously we have used Monte Carlo simulations in an ensemble with constant normal pressure to study prewetting transitions in adsorption from a single component undersaturated vapor in the approach to saturation: In this paper we present comparisons of our simulations results with predictions from density functional theory. We also discuss the use of simulations to determine more precisely the conditions for phase equilibrium at the prewetting transition through determination of the surface tension at the fluid-solid interface. We present results which extend these studies to the case of adsorption from a liquid mixture with a miscibility gap. In this work we have considered a symmetric Lennard-Jones mixture (sigma-11 = sigma-22 = sigma-12; epsilon-11 = epsilon-22 = epsilon, epsilon-12 = 0.75-epsilon). We describe Monte Carlo simulations of this mixture in contact with a wall which preferentially adsorbs one of the components. At several temperatures below the consolute temperature we studied adsorption at the solid surface for various compositions in the approach to coexistence from the phase rich in the weakly adsorbed component. Within the limited precision of the results obtained thus far, the system shows behavior suggesting complete wetting at higher temperatures and partial wetting at lower temperatures. Density functional theory predicts a first order wetting transition with a prewetting line for this system. C1 UNIV MASSACHUSETTS,DEPT CHEM ENGN,AMHERST,MA 01003. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 34 TC 3 Z9 3 U1 4 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-3812 J9 FLUID PHASE EQUILIBR JI Fluid Phase Equilib. PD AUG 14 PY 1992 VL 75 BP 163 EP 183 DI 10.1016/0378-3812(92)87015-F PG 21 WC Thermodynamics; Chemistry, Physical; Engineering, Chemical SC Thermodynamics; Chemistry; Engineering GA JL556 UT WOS:A1992JL55600015 ER PT J AU KEPPENNE, CL GHIL, M AF KEPPENNE, CL GHIL, M TI EXTREME WEATHER EVENTS SO NATURE LA English DT Letter C1 JET PROP LAB,PASADENA,CA 91109. RP KEPPENNE, CL (reprint author), UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024, USA. NR 8 TC 12 Z9 12 U1 1 U2 6 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD AUG 13 PY 1992 VL 358 IS 6387 BP 547 EP 547 DI 10.1038/358547a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JH829 UT WOS:A1992JH82900040 ER PT J AU LIU, HK BARHEN, J FARHAT, NH AF LIU, HK BARHEN, J FARHAT, NH TI OPTICAL IMPLEMENTATION OF TERMINAL-ATTRACTOR-BASED ASSOCIATIVE MEMORY SO APPLIED OPTICS LA English DT Article DE TERMINAL ATTRACTOR; ASSOCIATIVE MEMORY; HOPFIELD MODEL; INNER-PRODUCT ARCHITECTURE; LIQUID-CRYSTAL SPATIAL LIGHT MODULATORS ID NEURAL NETWORKS; MODEL AB For the purpose of reducing the spurious states in a Hopfield neural net for associative memory, we invoke terminal attractors. In achieving the optical implementation of the terminal-attractor-based associative memory (TABAM) as described in this paper, we first prove the existence of the terminal-attractor model with binary neuron representation. We then present several one- and two-dimensional optical architectures for the TABAM. Finally, as an example, we experimentally demonstrate an inner-product optical neural model using liquid-crystal spatial light modulators with engineering approximations and discuss how to apply the inner-product model to build a two-dimensional parallel processing TABAM. C1 UNIV PENN,MOORE SCH ELECT ENGN,PHILADELPHIA,PA 19104. RP LIU, HK (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 14 TC 5 Z9 5 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 10 PY 1992 VL 31 IS 23 BP 4631 EP 4644 PG 14 WC Optics SC Optics GA JH623 UT WOS:A1992JH62300007 PM 20725473 ER PT J AU DONE, C MULCHAEY, JS MUSHOTZKY, RF ARNAUD, KA AF DONE, C MULCHAEY, JS MUSHOTZKY, RF ARNAUD, KA TI AN IONIZED ACCRETION DISK IN CYGNUS X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; RADIATION MECHANISMS, COMPTON AND INVERSE COMPTON; STARS, INDIVIDUAL (CYGNUS X-1); X-RAYS, STARS ID X-RAY-SPECTRUM; ACTIVE GALACTIC NUCLEI; COLD MATTER; SEYFERT-1 GALAXIES; LINE EMISSION; IRON FEATURES; BLACK-HOLES; MASS-LOSS; VARIABILITY; BINARIES AB We have analyzed archival EXOSAT and HEAO 1-A2 observations of Cyg X-1. We find, in agreement with Ebisawa, that the X-ray spectrum of Cyg X-1 exhibits a "high-energy excess" above 8 keV, similar to that seen in Ginga spectra of active galactic nuclei. We show for the first time, using a likelihood ratio test, that the data are significantly better fit by a Compton reflection model than by a partial covering model. Even with the energy resolution of the EXOSAT GSPC we find that the derived iron line energy and shape are very dependent on the continuum model used. Using the best-fit Compton reflection model we find that the Fe line is not required to be either redshifted or broadened, although the data cannot distinguish between the skewed line profile expected from an illuminated accretion disk and a Gaussian line shape. The extended, 2-60 keV, energy response of the HEAO 1-A2 data can constrain the intrinsic continuum form. We find that the best-fit temperature for a Sunyaev-Titarchuk Comptonization model is significantly larger than that found in previous analysis based primarily on data in the 30-150 keV band. This suggests that the 5-50 keV continuum is not well fit by the same spectral form applicable at high energies and that a multiple temperature thermal Compton model is necessary to fit the broad-band data. The relative intensity of the Compton reflection component, combined with the known parameters of the Cyg X-1 system, is consistent with several models of the system, namely: 1. A point source origin of the X-ray emission situated above a flat disk with twice cosmic abundances, or 2. A spherical, optically thick source at the center of flat disk in which only Fe is over abundant, or 3. A optically thick source at the center of a flared disk with twice solar abundance. The measured Fe edge in the reflection spectrum is predominantly due to iron more ionized that Fe xv, inconsistent with that expected from a Shakura-Sunyaev disk. However the relatively low equivalent width of the Fe line, 44+/-28 eV is considerably smaller than that expected from a disk also responsible for the high-energy continuum. Only the line predicted from (3) gives a line within approximately 3-sigma of that observed, but a similar effect seen in other X-ray binary systems suggests that the lack of direct connection between the line intensity and reflection spectrum normalization may be a more widespread problem in models of X-ray illuminated accretion disks. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 67 TC 234 Z9 234 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP 275 EP 288 DI 10.1086/171649 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF699 UT WOS:A1992JF69900024 ER PT J AU GUTIERREZMORENO, A MORENO, H FEIBELMAN, WA AF GUTIERREZMORENO, A MORENO, H FEIBELMAN, WA TI ULTRAVIOLET OBSERVATIONS OF THE SYMBIOTIC STAR AS-296 SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, SYMBIOTIC; STARS, INDIVIDUAL (AS-296); ULTRAVIOLET, STARS ID SPECTRAL TYPES; WHITE-DWARFS; PHOTOMETRY; OUTBURST; MODEL AB AS 296 is a well-known S-type symbiotic star which underwent an optical outburst during 1988. In this paper, UV data based on IUE observations obtained both during the quiescent and outburst stages are presented and discussed, correlating them to observations made in the optical region. It is concluded that the object is a symbiotic nova, in which the outburst is due to a thermonuclear runaway produced in the hydrogen-burning shell of a white dwarf with M almost-equal-to 0.5 M., accreting from the late-type giant at a rate M(acc) almost-equal-to 9.7 x 10(9) M. yr-1. It is not possible to determine from the observations if the hydrogen flash is degenerate or nondegenerate. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP GUTIERREZMORENO, A (reprint author), UNIV CHILE,DEPT ASTRON,CASILLA 36-D,SANTIAGO,CHILE. NR 28 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP 295 EP 300 DI 10.1086/171651 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF699 UT WOS:A1992JF69900026 ER PT J AU SALAMA, F ALLAMANDOLA, LJ AF SALAMA, F ALLAMANDOLA, LJ TI THE ULTRAVIOLET AND VISIBLE SPECTRUM OF THE POLYCYCLIC AROMATIC HYDROCARBON C10H8+ - POSSIBLE CONTRIBUTIONS TO THE DIFFUSE INTERSTELLAR BANDS AND TO THE ULTRAVIOLET VISIBLE EXTINCTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, MOLECULES; LINE, IDENTIFICATION; MOLECULAR DATA ID ABSORPTION-SPECTRA; INFRARED-SPECTRUM; EMISSION BANDS; IR EMISSION; NAPHTHALENE; FEATURES; CATIONS; DUST; SPECTROSCOPY; IONIZATION AB This report describe the properties of the cation of the PAH naphthalene (C10H8+) isolated in inert gas matrices under conditions relevant to astrophysical environments. As with other PAH cations, C10H8+ absorbs in the visible. C10H8+ discrete absorption bands fall at 6741, 6520, 6376, 6314, 6151, 5965, 5848, 5784, 5658, 5503, 5341, 5114, and 4560 angstrom. The band at 6741 angstrom is the strongest and falls close to the weak 6742 angstrom DIB. Five other weaker bands (6376, 6314, 5848, 5784, and 5503) also fall remarkably close to the positions of known diffuse interstellar bands (DIBs). The possibility that C10H8+ is responsible for some of the diffuse interstellar bands can be tested by searching for new DIBS at 6520, 6151 and 5965 angstrom, other strong naphthalene cation band positions. If C10H8+ is indeed responsible for the 6742 angstrom feature, it accounts for 0.3% of the cosmic carbon. We also report a remarkably intense, but puzzling, very broad continuum extending from the UV to the visible (2000-3800 angstrom, with a weak tail extending to almost-equal-to 5100 angstrom) which seems to be associated with the ion. The molar absorption coefficient (epsilon) at the peak of the continuum is 2.0 x 10(6) dm3 mol-1 cm-1 (sigma(e) = 7.6 x 10(-15) cm2 molecule-1). If a continuum is a general property of PAH cations, this characteristic will have a strong impact on our understanding of how PAHs convert interstellar UV and visible radiation into IR radiation. We also note that neutral naphthalene may contribute to the 2200 angstrom bump. To produce a detectable feature at 2116 angstrom however, requires a high abundance. RP SALAMA, F (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-6,MOFFETT FIELD,CA 94035, USA. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 32 TC 91 Z9 92 U1 2 U2 8 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP 301 EP 306 DI 10.1086/171652 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF699 UT WOS:A1992JF69900027 ER PT J AU CHEN, PC CORNETT, RH ROBERTS, MS BOHLIN, RC NEFF, SG OCONNELL, RW PARISE, RA SMITH, AM STECHER, TP AF CHEN, PC CORNETT, RH ROBERTS, MS BOHLIN, RC NEFF, SG OCONNELL, RW PARISE, RA SMITH, AM STECHER, TP TI ULTRAVIOLET IMAGING TELESCOPE OBSERVATIONS OF THE SCI GALAXY NGC-628 (M74) SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-628); GALAXIES, SPIRAL; H-II REGIONS; ULTRAVIOLET, GALAXIES ID SPIRAL GALAXIES AB Ultraviolet images of NGC 628 at 1520 and 2490 angstrom show that the nucleus has an oblong appearance and that the arms and disk exhibit features not seen in blue or H-alpha images. Aperture photometry of the nucleus gives results that are compatible with observations in other bandpasses and with models. The spiral arms appear more symmetrical in the UV than in other colors; in particular, two gaps are seen on either side of the nucleus. Combined UV and radio data appear to support a large-scale collective phenomenon, perhaps a quasi-static spiral structure mechanism, as being the dominant mode of spiral formation in this galaxy. We report the detection of a low surface brightness object at a distance of 7'.6 southwest of the nucleus. C1 NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. RP CHEN, PC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,CODE 684,GREENBELT,MD 20771, USA. NR 20 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L41 EP L43 DI 10.1086/186484 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000011 ER PT J AU CHENG, KP MICHALITSIANOS, AG HINTZEN, P BOHLIN, RC OCONNELL, RW CORNETT, RH ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP AF CHENG, KP MICHALITSIANOS, AG HINTZEN, P BOHLIN, RC OCONNELL, RW CORNETT, RH ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP TI ASTRO-1 ULTRAVIOLET IMAGING OF THE 30 DORADUS AND SN-1987A FIELDS WITH THE ULTRAVIOLET IMAGING TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; H-II REGIONS; ISM, BUBBLES; MAGELLANIC CLOUDS; STARS, FUNDAMENTAL PARAMETERS; SUPERNOVA REMNANTS; ULTRAVIOLET, GENERAL ID NEBULA; STARS AB During the Astro-1 mission, near- and far-UV images of selected fields in the Magellanic Clouds were obtained using the Ultraviolet Imaging Telescope (UIT). These ultraviolet images, centered on SN 1987A, 30 Doradus, supernova remnants N49A+B, and SMC-A, provide the first wide-field (40' in diameter), high spatial resolution (2"-3") UV images of these regions. The 30 Doradus data reveal a rich field of luminous. UV-bright stars, clusters, and associations: within the 3' diameter central cluster, there are 181 stars brighter than m2558 = 16.5, and 197 stars brighter than M1615 = 16.4. We have derived UV fluxes from the 30 Doradus central cluster and from its UV-bright core, R136. A region within 5" of R136 produces approximately 14% of the far-UV flux (lambda = 1892 angstrom) and approximately 16% of the near-UV flux (lambda = 2558 angstrom) emitted from the 3' diameter central cluster. The derived UV luminosity of R136 at 1892 angstrom is only 7.8 times that of the nearby O6-O7 Iaf star, R139, and the m1892 - m(v) colors of R136 are similar to other O or Wolf-Rayet stars in the same region. The UIT data, combined with published observations at longer wavelengths, indicate that there is no observational evidence for a supermassive star in R136. In the UIT images, we also detect an extensive dust feature, which extends throughout the 30 Doradus and SN 1987A fields. Diffuse UV emission at low flux levels runs from northeast to southwest at the northern boundary of N157A, N157B, and N157C, corresponding closely to the extended infrared emission seen in the IRAS 60-mu-m high-resolution (HiRes) image. The observed correlation between the UV and the IR emission suggests that the dust scatters a substantial fraction of the incident UV photons, while absorbing some of the remainder and reemitting this energy in the IR. We have compared the UIT images with the Einstein X-ray images, IRAS HiRes images, and ground-based CCD fields in [O III] lambda-5007, H-alpha, B, R, U, and Stromgren u. This comparison is extremely useful in identifying and studying large H II regions, stellar windblown cavities, and extended large-scale filaments which are delineated largely by the expansion of supernova shells. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV NEVADA,DEPT PHYS & ASTRON,LAS VEGAS,NV 89154. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NATL RADIOL ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. HUGHES STX CORP,LANHAM,MD 20706. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NR 18 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L29 EP & DI 10.1086/186481 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000008 ER PT J AU CORNETT, RH JENKINS, EB BOHLIN, RC CHENG, KP GULL, TR OCONNELL, RW PARKER, RAR ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP AF CORNETT, RH JENKINS, EB BOHLIN, RC CHENG, KP GULL, TR OCONNELL, RW PARKER, RAR ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP TI ULTRAVIOLET IMAGING TELESCOPE OBSERVATIONS OF THE CYGNUS LOOP SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUPERNOVA REMNANTS; ULTRAVIOLET,GENERAL ID SUPERNOVA-REMNANTS; SHOCK-WAVE; X-RAY; EMISSION; MODELS AB Ultraviolet images of a 40' field in the northeast part of the Cygnus Loop were made by the Ultraviolet Imaging Telescope (UIT) during the Astro-1 mission in 1990 December. This Letter compares the longest far-UV (B5) exposure with ground-based and X-ray observations and with models. At bright knots observed by IU E, the B5 bandpass includes flux from several lines. However, supernova remnant (SNR) shock models imply that C IV lambda-1550 dominates for more typical conditions in SNRs, and IU E spectra demonstrate a strong correlation between C IV lambda-1550 flux and UIT B5 flux. The B5 image resembles images in [O III] lambda-5007, but to the east of the edge of thc [O III] filaments there is a faint C IV emission, consistent with nonradiative shocked material behind the SNR blast wave. Conditions in shocked gases that lead to C IV emission are similar to those that produce [O III]. Hence the ratio of the B5 and [O III] intensities can be used to map the optical depths of the sheetlike regions that emit the C IV resonance line. A feature in the B5 emission closely follows a "bow shock" shape in Einstein HRI imagery; its morphology is consistent with an encounter of the SNR shock with a cloud outlined by a column density enhancement found in H I maps. C1 PRINCETON UNIV OBSERV,PRINCETON,NJ 08544. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NASA HEADQUARTERS,WASHINGTON,DC 20546. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP CORNETT, RH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,CODE 681,GREENBELT,MD 20771, USA. RI Gull, Theodore/D-2753-2012; Jenkins, Edward/P-5684-2014 OI Gull, Theodore/0000-0002-6851-5380; Jenkins, Edward/0000-0003-1892-4423 NR 20 TC 22 Z9 22 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L9 EP & DI 10.1086/186476 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000003 ER PT J AU CROTTS, APS LANDSMAN, WB BOHLIN, RC OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP AF CROTTS, APS LANDSMAN, WB BOHLIN, RC OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP TI OBSERVATIONS OF THE LIGHT ECHOES FROM SN-1987A USING THE ASTRO-1 ULTRAVIOLET IMAGING TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; SUPERNOVAE, INDIVIDUAL (SN-1987A); ULTRAVIOLET, STARS ID LARGE MAGELLANIC CLOUD; SN1987A AB We present the results from images taken of the region of the light echoes around SN 1987A, as acquired on the first flight of the Astro-1 Ultraviolet Imaging Telescope (UIT). They indicate a weighted-average ultraviolet echo surface brightness of almost-equal-to 3 x 10-(18) ergs s-1 cm-2 angstrom-1 arcsec-2. This is consistent with earlier results obtained by the International Ultraviolet Explorer, when scaled by the optical surface brightnesses of the two different echoes observed. These results indicate that the ultraviolet flux emitted by the shock from core collapse penetrating the stellar surface cannot be as strong as that predicted by a large class of theoretical models (cited herein), or that previous results on the optical scattering of echoing dust do not apply to these clouds. Prospects for a more accurate measurement, once the echoes have propagated to other regions and a background measurement can be obtained with UIT, are discussed. They indicate that a more accurate determination of the above results is probable with another epoch of UIT observations. C1 COLUMBIA UNIV,DEPT ASTRON,NEW YORK,NY 10027. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP CROTTS, APS (reprint author), ASSOC UNIV RES ASTRON INC,NATL OPT ASTRON OBSERV,CERRO TOLOLO INTERAMER OBSERV,TUCSON,AZ 85726, USA. NR 19 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L25 EP L27 DI 10.1086/186480 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000007 ER PT J AU HENNESSY, GS OCONNELL, RW CHENG, KP BOHLIN, RC COLLINS, NR GULL, TR HINTZEN, P ISENSEE, JE LANDSMAN, WB ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP AF HENNESSY, GS OCONNELL, RW CHENG, KP BOHLIN, RC COLLINS, NR GULL, TR HINTZEN, P ISENSEE, JE LANDSMAN, WB ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP TI ULTRAVIOLET IMAGING TELESCOPE OBSERVATIONS OF THE CRAB-NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUPERNOVA REMNANTS; ISM,INDIVIDUAL OBJECTS (CRAB NEBULA) ID INTER-STELLAR EXTINCTION; DUST AB We obtained ultraviolet images of the Crab Nebula with the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Space Shuttle mission in 1990 December. The UV continuum morphology of the Crab is generally similar to that in the optical region, but the wispy structures are less conspicuous in the UV and X-ray. UV line emission from the thermal filaments is not strong. UV spectral index maps with a resolution of 10" show a significant gradient across the nebula, with the outer parts being redder, as expected from synchrotron losses. The location of the bluest synchrotron continuum does not coincide with the pulsar. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. UNIV NEVADA,DEPT PHYS,LAS VEGAS,NV 89154. RP HENNESSY, GS (reprint author), UNIV VIRGINIA,DEPT ASTRON,POB 3818,CHARLOTTESVILLE,VA 22903, USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 27 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L13 EP & DI 10.1086/186477 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000004 ER PT J AU HILL, JK BOHLIN, RC CHENG, KP HINTZEN, PMN LANDSMAN, WB NEFF, SG OCONNELL, RW ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP AF HILL, JK BOHLIN, RC CHENG, KP HINTZEN, PMN LANDSMAN, WB NEFF, SG OCONNELL, RW ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP TI ULTRAVIOLET IMAGING TELESCOPE ULTRAVIOLET IMAGES - LARGE-SCALE STRUCTURE, H-II REGIONS, AND EXTINCTION IN M81 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ULTRAVIOLET, GALAXIES; GALAXIES, INDIVIDUAL, M81; ISM, H-II REGIONS ID ROCKET ULTRAVIOLET; SPIRAL GALAXY-M81; GALAXIES; LUMINOSITY; DYNAMICS; MODELS; STAR AB Ultraviolet images of M81 obtained by the Ultraviolet Imaging Telescope during the 1990 December Astro-1 spacelab mission allow determination of 2490 and 1520 angstrom fluxes for 46 H II regions and global surface brightness profiles. Comparison photometry in the V band is obtained from a ground-based CCD image. Ultraviolet radial profiles show bulge and exponential disk components, with a local decrease in disk surface brightness inside the inner Lindblad Resonance approximately 4' from the nucleus. The V profile shows typical bulge plus exponential disk structure, with no local maximum in the disk. There is little change of UV color across the disk, although there is a strong gradient in the bulge. The ratio of the near-UV surface brightness to the V band surface brightness in the disk is a factor approximately 4 lower for M81 than for M51. Total near-UV and far-UV UIT fluxes for M81 are consistent with previous measurements by O AO 2. The flux from the bulge is estimated to be 53% of the total in the V band, 31% in the near-UV, and 5% in the far-UV. Observed M152 - V colors of the H II regions are consistent with model spectra for young clusters, after dereddening using A(v) determined from m249 - V and the Galactic extinction curve. The value of A(v), so determined, is 0.4 mag greater on the average than A(v) derived from radio continuum and H-alpha fluxes. This difference is within the error estimates of the ground-based extinction determinations. The observed colors are unlikely to be caused by larger ages than the 3 Myr assumed by the model, since the Lyman continuum flux of a cluster is a strongly decreasing function of age. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. UNIV NEVADA,DEPT PHYS & ASTRON,LAS VEGAS,NV 89154. UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. RP HILL, JK (reprint author), HUGHES STX CORP,4400 FORBES BLVD,LANTHAM,MD 20706, USA. NR 19 TC 32 Z9 32 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L37 EP L40 DI 10.1086/186483 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000010 ER PT J AU HILL, JK PFARR, BB BOHLIN, RC ISENSEE, JE OCONNELL, RW NEFF, SG ROBERTS, MS SMITH, AM STECHER, TP AF HILL, JK PFARR, BB BOHLIN, RC ISENSEE, JE OCONNELL, RW NEFF, SG ROBERTS, MS SMITH, AM STECHER, TP TI ULTRAVIOLET IMAGING TELESCOPE PHOTOMETRY OF MASSIVE STARS - THE OB ASSOCIATION NGC-206 IN M31 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL, M31; ULTRAVIOLET, GENERAL ID STELLAR AB The Ultraviolet Imaging Telescope (UIT) obtained UV images of the giant M31 OB association NGC 206. Magnitudes in bands at 1520 and 2490 angstrom were obtained for 30 massive stars, which demonstrate the effectiveness of UIT for photometry of moderately crowded hot stars to V approximately 21. The UV colors and magnitudes observed for stars in NGC 206 place them in the region of the color-magnitude diagram occupied by evolutionary models for 30-60 M. stars, after correcting for extinction. The brighter stars are systematically redder than the fainter stars, indicating that they are supergiants of age approximately 4 Myr, while the fainter, bluer stars are nearer age zero. The relative numbers of probable supergiants measured by us and the number of probable main-sequence O stars measured from optical images are in agreement with the relative lifetimes. Calculated UIT colors are presented for a library of standard star spectra constructed from IUE and ground-based observations. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,DIV MISSION OPERAT,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HILL, JK (reprint author), HUGHES STX CORP,4400 FORBES BLVD,LANHAM,MD 20706, USA. RI Pfarr, Barbara/C-6785-2015 NR 11 TC 11 Z9 11 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L33 EP L35 DI 10.1086/186482 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000009 ER PT J AU HILL, RS HILL, JK LANDSMAN, WB BOHLIN, RC CHENG, KP HINTZEN, PMN OCONNELL, RW ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP AF HILL, RS HILL, JK LANDSMAN, WB BOHLIN, RC CHENG, KP HINTZEN, PMN OCONNELL, RW ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP TI AN ULTRAVIOLET IMAGING TELESCOPE STUDY OF THE GLOBULAR-CLUSTER M79 (NGC-1904) SO ASTROPHYSICAL JOURNAL LA English DT Article DE GLOBULAR CLUSTERS, INDIVIDUAL, NGC-1904; STARS, HORIZONTAL-BRANCH; STARS, POSTASYMPTOTIC GIANT BRANCH; ULTRAVIOLET, STARS ID HORIZONTAL-BRANCH STARS; PHOTOMETRY; EVOLUTION AB The Ultraviolet Imaging Telescope (UIT) detects approximately 100 blue and extremely blue horizontal-branch (HB) stars in M79. Comparison of the ultraviolet color-magnitude diagram of M79 with stellar interior models shows that the distribution of total masses of the detected stars along with the zero-age HB includes the range of 0.495-0.62 M., corresponding to envelope masses 0.01-0.13 M.. The total number of HB stars in M79 is estimated at 220 +/- 10. Also detected are two hot stars brighter than the horizontal branch by at least 1.5 mag at 1520 angstrom. One of these stars (UIT 1) appears to be descending in luminosity along a pre-white dwarf track. The other (UIT 2) is most likely a post-HB star evolving toward the asymptotic giant branch. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV NEVADA,DEPT PHYS & ASTRON,LAS VEGAS,NV 89154. UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. RP HILL, RS (reprint author), HUGHES STX CORP,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 26 TC 17 Z9 17 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L17 EP & DI 10.1086/186478 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000005 ER PT J AU LANDSMAN, WB OCONNELL, RW WHITNEY, JH BOHLIN, RC HILL, RS MARAN, SP PARISE, RA ROBERTS, MS SMITH, AM STECHER, TP AF LANDSMAN, WB OCONNELL, RW WHITNEY, JH BOHLIN, RC HILL, RS MARAN, SP PARISE, RA ROBERTS, MS SMITH, AM STECHER, TP TI THE ULTRAVIOLET-BRIGHT STARS OF OMEGA CENTAURI, M3, AND M13 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GLOBULAR CLUSTERS,INDIVIDUAL M3, M13, OMEGA CENTAURI); STARS,POST ASYMPTOTIC GIANT BRANCH; ULTRAVIOLET,STARS ID GLOBULAR-CLUSTERS; ELLIPTIC GALAXIES; IUE OBSERVATIONS; BRANCH STARS; MASS-LOSS; X-RAY; EVOLUTION; TELESCOPE AB Far-ultraviolet (1620 angstrom) images were obtained of the globular clusters omega-Cen, M3, and M13 with the Ultraviolet Imaging Telescope (UIT) on the Astro-1 mission. The large field of view and solar-blind response of UIT allow complete identification of all UV-bright objects in these clusters. Two new UV-bright stars are detected within 2' of the center of omega-Cen and have been spectroscopically investigated with the short-wavelength spectrograph on the International Ultraviolet Explorer (IU E). The known UV-bright stars ROA 5701 (in omega-Cen), vZ 1128 (M3) and Barnard 29 (in M13) are also conspicuous on the UIT images. The IU E spectra of the UV-bright stars UIT-1 and UIT-2 in the core of omega-Cen superficially resemble those of Population I mid-B stars. However, the absorption lines of the core UV-bright stars are significantly weaker than in Populations I stars, consistent with their membership in the cluster. Synthetic spectra calculated from low-metallicity Kurucz model stellar atmospheres are compared with the spectra. The best fits are obtained for effective temperature T(eff) = 18,000, and luminosity log L/L. = 3.0 for UIT-1, and T(eff) = 19,000, log L/L. = 2.6 for UIT-2. These objects are insufficiently luminous to be classical hydrogen-burning post-AGB stars. They may be evolved hot horizontal branch stars which have brightened by more than 3 mag since leaving the zero-age horizontal branch. Another possibility is that they are post early-AGB stars which leave the AGB before the onset of thermal pulsations. The spectra and luminosity of the core UV-bright stars suggest that similar objects could provide the source of the ultraviolet light in elliptical galaxies. C1 NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. RP LANDSMAN, WB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,CODE 681,GREENBELT,MD 20771, USA. NR 38 TC 21 Z9 21 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L21 EP & DI 10.1086/186479 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000006 ER PT J AU OCONNELL, RW BOHLIN, RC COLLINS, NR CORNETT, RH HILL, JK HILL, RS LANDSMAN, WB ROBERTS, MS SMITH, AM STECHER, TP AF OCONNELL, RW BOHLIN, RC COLLINS, NR CORNETT, RH HILL, JK HILL, RS LANDSMAN, WB ROBERTS, MS SMITH, AM STECHER, TP TI ULTRAVIOLET IMAGING OF OLD POPULATIONS IN NEARBY GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (M31, M32, M81, NGC-1339); GALAXIES, PHOTOMETRY; GALAXIES, STELLAR CONTENT; ULTRAVIOLET, GENERAL ID CCD SURFACE PHOTOMETRY; ELLIPTIC GALAXIES; IUE OBSERVATIONS; CENTRAL BULGE; M31; STARS; FLUX; M81 AB We analyze UV imagery of two Sb bulges and two E galaxies obtained with the Ultraviolet Imaging Telescope during the Astro-1 mission. The UV brightness of these systems is not produced by recent massive star formation. Instead, it must originate in relatively low-luminosity objects, probably low-mass, post-giant-branch stars. We find extended, large-amplitude UV color gradients, which are probably related to abundance gradients within the galaxies. M32 has a color gradient opposite to the other three objects, possibly because of an intermediate-age population. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. RP OCONNELL, RW (reprint author), UNIV VIRGINIA,DEPT ASTRON,POB 3818,CHARLOTTESVILLE,VA 22903, USA. NR 33 TC 55 Z9 55 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L45 EP L48 DI 10.1086/186485 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000012 ER PT J AU SMITH, EP OCONNELL, RW BOHLIN, RC CHENG, KP CORNETT, RH HILL, JK HILL, RS HINTZEN, P LANDSMAN, WB NEFF, SG ROBERTS, MS SMITH, AM STECHER, TP AF SMITH, EP OCONNELL, RW BOHLIN, RC CHENG, KP CORNETT, RH HILL, JK HILL, RS HINTZEN, P LANDSMAN, WB NEFF, SG ROBERTS, MS SMITH, AM STECHER, TP TI IMPLICATIONS OF ULTRAVIOLET IMAGING TELESCOPE OBSERVATIONS FOR STAR FORMATION HISTORIES IN NGC-1275 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; GALAXIES, INDIVIDUAL (NGC-1275); STARS, FORMATION ID COOLING FLOWS; DOMINANT GALAXIES; PERSEUS CLUSTER; EMISSION; GAS; FILAMENTS; EVOLUTION; NUCLEUS; TABLES; MODELS AB We discuss UV imagery of NGC 1275 obtained using the Goddard Ultraviolet Imaging Telescope (UIT). We are able to study the UV morphology down to mu-249 approximately 25 mag arcsec-2. There are significant non-axisymmetric structures in the UV continuum associated with the low-velocity filament system. Continuum from the high-velocity system may also be present. The large-aperture UV colors indicate that although the mass function extends to approximately 5 M., more massive objects are not present. This implies either a cessation of star formation during the last approximately 50-100 Myr or a truncated initial mass function. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. UNIV NEVADA,DEPT PHYS,LAS VEGAS,NV 89154. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NR 50 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L49 EP L54 DI 10.1086/186486 PN 2 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000013 ER PT J AU STECHER, TP BAKER, GR BARTOE, DD BAUER, FH BLUM, A BOHLIN, RC BUTCHER, HR CHEN, PC COLLINS, NR CORNETT, RH DEILY, JJ GREASON, MR HENNESSY, GS HILL, JK HILL, RS HINTZEN, PM ISENSEE, JE KENNY, PJ LANDSMAN, WB LINARD, DL MARAN, SP NEFF, SG NICHOLS, GR NOVELLO, J OCONNELL, RW OFFENBERG, JD PARISE, RA PFARR, BB PLUMMER, TB RICHARDSON, FF ROBERTS, MS SITKO, SD SMITH, AM STOBER, AK STOLARIK, JD TEBAY, JC AF STECHER, TP BAKER, GR BARTOE, DD BAUER, FH BLUM, A BOHLIN, RC BUTCHER, HR CHEN, PC COLLINS, NR CORNETT, RH DEILY, JJ GREASON, MR HENNESSY, GS HILL, JK HILL, RS HINTZEN, PM ISENSEE, JE KENNY, PJ LANDSMAN, WB LINARD, DL MARAN, SP NEFF, SG NICHOLS, GR NOVELLO, J OCONNELL, RW OFFENBERG, JD PARISE, RA PFARR, BB PLUMMER, TB RICHARDSON, FF ROBERTS, MS SITKO, SD SMITH, AM STOBER, AK STOLARIK, JD TEBAY, JC TI THE ULTRAVIOLET IMAGING TELESCOPE - DESIGN AND PERFORMANCE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ARTIFICIAL SATELLITES, SPACE PROBES; TELESCOPES AB The Ultraviolet Imaging Telescope (UIT) was flown as part of the. Astro-1 Spacelab mission on the Space Shuttle Columbia in 1990 December. The ultraviolet images of a wide variety of astronomical objects were recorded with a 40' diameter field of view. Images of targets as faint as magnitude 21 (ultraviolet) were secured with a resolution of about 3". This Letter describes the design, flight operations, data reduction, and overall technical performance of the UIT. C1 NASA HEADQUARTERS,WASHINGTON,DC 20546. NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE TECHNOL,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. KAPTEYN OBSERV,9301 KA RODEN,NETHERLANDS. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. KENNEDY SPACE CTR,KENNEDY SPACE CTR,FL 32899. UNIV NEVADA,DEPT PHYS & ASTRON,LAS VEGAS,NV 89154. RP STECHER, TP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 680,GREENBELT,MD 20771, USA. RI Pfarr, Barbara/C-6785-2015 NR 1 TC 55 Z9 55 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L1 EP & DI 10.1086/186474 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000001 ER PT J AU WITT, AN PETERSOHN, JK BOHLIN, RC OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP AF WITT, AN PETERSOHN, JK BOHLIN, RC OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP TI ULTRAVIOLET IMAGING TELESCOPE IMAGES OF THE REFLECTION NEBULA NGC-7023 - DERIVATION OF ULTRAVIOLET SCATTERING PROPERTIES OF DUST GRAINS SO ASTROPHYSICAL JOURNAL LA English DT Article ID DIFFUSE GALACTIC LIGHT; VACUUM ULTRAVIOLET; FLUORESCENCE; HD-200775; REGION AB The Ultraviolet Imaging Telescope, as part of the Astro-1 mission, was used to obtain high-resolution surface brightness distribution data in six ultraviolet wavelength bands for the bright reflection nebula NGC 7023. From the quantitative comparison of the measured surface brightness gradients, ratios of nebular to stellar flux, and detailed radial surface brightness profiles with corresponding data from the visible, two major conclusions result: (1) the scattering in the near- and far-ultraviolet in this nebula is more strongly forward-directed than in the visible; (2) the dust albedo in the ultraviolet for lambda greater-than-or-equal-to 140 nm is identical to that in the visible, with the exception of the 220 nm bump in the extinction curve. In the wavelength region of the bump, the albedo is reduced by 25% to 30% in comparison with wavelength regions both shorter and longer. This lower albedo is expected, if the bump is a pure absorption feature. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WITT, AN (reprint author), UNIV TOLEDO,RITTER ASTROPHYS RES CTR,TOLEDO,OH 43606, USA. OI Witt, Adolf/0000-0003-0760-4483 NR 11 TC 58 Z9 58 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1992 VL 395 IS 1 BP L5 EP & DI 10.1086/186475 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF700 UT WOS:A1992JF70000002 ER PT J AU SHIMADA, S BOCK, Y AF SHIMADA, S BOCK, Y TI CRUSTAL DEFORMATION MEASUREMENTS IN CENTRAL JAPAN DETERMINED BY A GLOBAL POSITIONING SYSTEM FIXED-POINT NETWORK SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID PHILIPPINE SEA PLATE; PHASE AMBIGUITY RESOLUTION; BASE-LINE INTERFEROMETRY; RADIO INTERFEROMETRY; ORBIT DETERMINATION; GEODETIC BASELINES; IZU PENINSULA; CALIFORNIA; MOTION; EARTHQUAKE AB A Global Positioning System (GPS) fixed-point network has been operating in the Kanto and Tokai districts of central Japan since April 1988 to detect crustal deformation associated with the convergence of the Eurasian, Pacific, North American, and Philippine Sea plates and to monitor the deformation cycles of frequent large interplate and intraplate earthquakes. This 10-station network established by the National Research Institute for Earth Science and Disaster Prevention (NIED) is the first continuously monitoring network of its kind. We determine deformation within the network using two consecutive days of data every 2 weeks for the first 17 months of operations. We use a station and orbit relaxation method which relies exclusively on data collected within the NIED network, except for 1 week of global GPS tracking data which is used to determine initial station positions with respect to the global reference frame. We detect, relative to a station on the Eurasian plate in central Japan, significant westward motion of 28 mm/yr of the northern tip of the Philippine Sea plate, which is subducting beneath the Eurasian plate at the Suruga trough. Our results support finite element models of collision of the Izu Block with the Eurasian plate based on earthquake focal mechanisms and plate block motions of the Japanese archipelago determined from conventional geodetic measurements over the last century. We detect southwestward motion of 18 mm/yr of the southeastern tip of the Eurasian plate, confirming expected surface extension of the subducted plate parallel to the Suruga trough axis. Significant vertical uplift with a velocity of 20 mm/yr is suggested at a site inland of the Tokai district located in the Akaishi uplift zone and at a site on Hatsushima Island in Sagami Bay. The general tendency of vertical movements of the other sites agrees with vertical velocities obtained from 70 years of geodetic leveling and with Quaternary vertical displacements determined from geomorphological and other geological evidence. We detect no significant crustal motion across the Fossa Magna tectonic zone in central Japan (often considered a plate boundary), across the Tokyo metropolitan area, nor across the Sagami trough associated with the subduction of the Philippine Sea plate beneath northeast Japan. Our results demonstrate the power of regionally based, continuously monitoring GPS networks for obtaining temporally dense measurements of small horizontal and vertical crustal movements across plate boundary zones. C1 UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,INST GEOPHYS & PLANETARY PHYS,LA JOLLA,CA 92093. JET PROP LAB,PASADENA,CA 91109. RP SHIMADA, S (reprint author), NATL RES INST EARTH SCI & DISASTER PREVENT,TSUKUBA,IBARAKI 305,JAPAN. NR 90 TC 21 Z9 22 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD AUG 10 PY 1992 VL 97 IS B9 BP 12437 EP 12455 DI 10.1029/92JB00809 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JH992 UT WOS:A1992JH99200011 ER PT J AU KRAUSS, LM ROMANELLI, P SCHRAMM, D LEHRER, R AF KRAUSS, LM ROMANELLI, P SCHRAMM, D LEHRER, R TI THE SIGNAL FROM A GALACTIC SUPERNOVA - MEASURING THE TAU-NEUTRINO MASS SO NUCLEAR PHYSICS B LA English DT Article ID ANTINEUTRINO; BURST; 1987A AB We have developed a comprehensive Monte Carlo analysis in order to simulate the neutrino signal from a galactic supernova in a large water Cerenkov detector. This allows us to demonstrate that, by exploiting the various features of the signal in a way which is largely independent of the supernova model, assuming only that the late-time behaviour of the signal is flavor independent, a sensitivity to a tau-neutrino mass down to the cosmologically interesting range of almost-equal-to 25 eV for a medium luminosity burst is possible. This is the case even though the tau signal involves almost-equal-to 50 out of almost-equal-to 10000 total events in a detector of the size of that proposed for "Super Kamiokande". In addition, our results allow us to elucidate several aspects of a supernova neutrino signal in water detectors which had not been previously explored, including new results on the observability of the neutronization burst. C1 YALE UNIV, SLOANE LAB, DEPT ASTRON, NEW HAVEN, CT 06511 USA. BANKERS TRUST CO, NEW YORK, NY 10006 USA. UNIV CHICAGO, CHICAGO, IL 60637 USA. YALE UNIV, YALE COLL, NEW HAVEN, CT 06517 USA. NASA, FERMILAB ASTROPHYS CTR, BATAVIA, IL 60510 USA. RP KRAUSS, LM (reprint author), YALE UNIV, SLOANE LAB, CTR THEORET PHYS, NEW HAVEN, CT 06511 USA. NR 23 TC 16 Z9 16 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0550-3213 EI 1873-1562 J9 NUCL PHYS B JI Nucl. Phys. B PD AUG 10 PY 1992 VL 380 IS 3 BP 507 EP 542 DI 10.1016/0550-3213(92)90256-B PG 36 WC Physics, Particles & Fields SC Physics GA JH123 UT WOS:A1992JH12300009 ER PT J AU STOLARSKI, R AF STOLARSKI, R TI STRATOSPHERIC OZONE TRENDS - RESPONSE SO SCIENCE LA English DT Letter RP STOLARSKI, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Stolarski, Richard/B-8499-2013 OI Stolarski, Richard/0000-0001-8722-4012 NR 2 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 7 PY 1992 VL 257 IS 5071 BP 727 EP 728 DI 10.1126/science.257.5071.727-a PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JG851 UT WOS:A1992JG85100003 PM 17736447 ER PT J AU WEISSMAN, PR AF WEISSMAN, PR TI COMETARY JOKE SO NATURE LA English DT Letter ID OORT CLOUD; DUST RP WEISSMAN, PR (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD AUG 6 PY 1992 VL 358 IS 6386 BP 460 EP 460 DI 10.1038/358460a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JG739 UT WOS:A1992JG73900033 ER PT J AU SCHACHAM, SE HAUGLAND, EJ ALTEROVITZ, SA AF SCHACHAM, SE HAUGLAND, EJ ALTEROVITZ, SA TI ENHANCEMENT OF SHUBNIKOV-DEHAAS OSCILLATIONS BY CARRIER MODULATION SO APPLIED PHYSICS LETTERS LA English DT Article ID INTERSUBBAND SCATTERING; ELECTRON-GAS; HETEROJUNCTIONS; HETEROSTRUCTURES AB A drastic enhancement of the Shubnikov-de Haas (SdH) pattern is obtained by recording the changes in the quantum oscillations of magnetoresistance due to modulation of the carrier concentration. The technique enables measurement of the SdH waveform at relatively high temperatures and in samples with moderate mobilities. The modulated waveform shows selective enhancement of the low-frequency SdH oscillations associated with the upper subband. Thus, we were able to record very clear oscillations generated by a carrier concentration well below 5 X 10(10) cm-2. The theory for this selective enhancement is provided. RP SCHACHAM, SE (reprint author), NASA,LEWIS RES CTR,M-S 54-5,CLEVELAND,OH 44135, USA. NR 9 TC 12 Z9 12 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD AUG 3 PY 1992 VL 61 IS 5 BP 551 EP 553 DI 10.1063/1.107859 PG 3 WC Physics, Applied SC Physics GA JG157 UT WOS:A1992JG15700018 ER PT J AU RAY, TW FARR, TG VANZYL, JJ AF RAY, TW FARR, TG VANZYL, JJ TI DETECTION OF LAND DEGRADATION WITH POLARIMETRIC SAR SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Land degradation is a crucial problem facing the human race. With an ever-increasing population placing increasing stress on agricultural lands, land impoverishment has the potential for adversely impacting the food supply in many regions of the world. The Manix Basin Area of the Mojave desert has been cropped using center pivot irrigation, but since 1973 many fields have been abandoned for economic reasons. Data were collected using the JPL Airborne Synthetic Aperture Radar (AIRSAR), a multispectral radar polarimeter. Analysis of these data revealed unusual polarization responses which we attribute to the formation of wind ripples on the surfaces of fields which had. been abandoned for more than 5 years. This conjecture was confirmed through field observations, and the observed polarization responses were effectively modelled using a second-order small perturbation model. These results demonstrate the usefulness of remote sensing techniques supported by limited field work for study of land degradation at synoptic scales. C1 JET PROP LAB,PASADENA,CA 91109. RP RAY, TW (reprint author), CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125, USA. OI Farr, Thomas/0000-0001-5406-2096 NR 8 TC 0 Z9 0 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 3 PY 1992 VL 19 IS 15 BP 1587 EP 1590 DI 10.1029/92GL01580 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JH144 UT WOS:A1992JH14400015 ER PT J AU FERRARE, RA MELFI, SH WHITEMAN, DN EVANS, KD AF FERRARE, RA MELFI, SH WHITEMAN, DN EVANS, KD TI RAMAN LIDAR MEASUREMENTS OF PINATUBO AEROSOLS OVER SOUTHEASTERN KANSAS DURING NOVEMBER DECEMBER 1991 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Raman lidar measurements over southeastern Kansas of stratospheric aerosols produced by the June 1991 eruptions of Mt. Pinatubo were made on 10 nights during November and December 1991. Both aerosol backscattering and extinction profiles were derived simultaneously from the lidar data since this system detects Raman scattering from nitrogen and oxygen as well as the backscattered light from aerosols and molecules. Aerosol scattering ratios greater than 3 (at 351 nm) were measured on several nights. Peak aerosol concentrations were located between 19-22 km and varied significantly from night to night. Aerosol extinction/backscatter ratios computed from the lidar data and averaged over the altitude region of enhanced aerosol scattering between 15-25 km varied between 18-28 sr. Mie computations show these values to be consistent with scattering by aerosol particles with mode radii between 0.3 to 0.5-mu-m and that the ratios would increase to 40-65 sr at 694 nm. Aerosol optical thicknesses derived from the lidar extinction measurements at 351 nm varied between 0.04 and 0.06. C1 UNIV SPACE RES ASSOC,GREENBELT,MD. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. NR 14 TC 50 Z9 50 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 3 PY 1992 VL 19 IS 15 BP 1599 EP 1602 DI 10.1029/92GL01473 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JH144 UT WOS:A1992JH14400018 ER PT J AU LACIS, A HANSEN, J SATO, M AF LACIS, A HANSEN, J SATO, M TI CLIMATE FORCING BY STRATOSPHERIC AEROSOLS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EL-CHICHON; RADIATIVE PROPERTIES; SULFURIC-ACID; ATMOSPHERES; SCATTERING; ABSORPTION; ERUPTION; MODEL AB We illustrate how climate forcing by stratospheric aerosols depends on aerosol properties. The climate forcing is a function of aerosol size distribution, but the size dependence can be described well by a single parameter: the area-weighted mean radius, r(eff). If r(eff) is greater than about 2-mu-m, the global average greenhouse effect of the aerosols exceeds the albedo effect, causing a surface heating. The aerosol climate forcing is less sensitive to other characteristics of the size distribution, the aerosol composition, and the altitude of the aerosols. Thus stratospheric aerosol forcing can be defined accurately from measurements of aerosol extinction over a broad wavelength range. RP LACIS, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GODDARD INST SPACE STUDIES,2880 BROADWAY,GREENBELT,MD 20771, USA. RI Lacis, Andrew/D-4658-2012 NR 21 TC 166 Z9 173 U1 2 U2 14 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 3 PY 1992 VL 19 IS 15 BP 1607 EP 1610 DI 10.1029/92GL01620 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JH144 UT WOS:A1992JH14400020 ER PT J AU SHI, X SCHRAMM, DN BAHCALL, JN AF SHI, X SCHRAMM, DN BAHCALL, JN TI MONTE-CARLO EXPLORATION OF MIKHEYEV-SMIRNOV-WOLFENSTEIN SOLUTIONS TO THE SOLAR NEUTRINO PROBLEM SO PHYSICAL REVIEW LETTERS LA English DT Article ID OSCILLATIONS; MATTER; MASS; SUN AB We explore the impact of astrophysical uncertainties on the Mikheyev-Smirnov-Wolfenstein (MSW) solution by calculating the allowed MSW solutions for 1000 different solar models with a Monte Carlo selection of solar model input parameters, assuming a full three-family MSW mixing. Applications are made to the chlorine, gallium, Kamiokande, and Borexino experiments. The initial GALLEX result limits the mixing parameters to the upper diagonal and the vertical regions of the MSW triangle. We also calculate the expected event rates in the Borexino experiment assuming the MSW solutions implied by GALLEX. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. INST ADV STUDY,PRINCETON,NJ 08540. RP SHI, X (reprint author), UNIV CHICAGO,CHICAGO,IL 60637, USA. NR 23 TC 63 Z9 64 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD AUG 3 PY 1992 VL 69 IS 5 BP 717 EP 720 DI 10.1103/PhysRevLett.69.717 PG 4 WC Physics, Multidisciplinary SC Physics GA JG115 UT WOS:A1992JG11500007 ER PT J AU DUKE, MB AF DUKE, MB TI HUMAN EXPLORATION AND SETTLEMENT OF MARS - THE ROLES OF HUMANS AND ROBOTS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB The Space Exploration Initiative (SEI) will require both robots and humans to achieve its objectives. A strategy is suggested for the development of an automation and robotics clement of the SEI which would facilitate the evolution of systems from robotic to telerobotic to human-supervised robotic capabilities, as the focus of the SEI evolves from science and exploration to human presence emphases. RP DUKE, MB (reprint author), NASA,HOUSTON,TX 77058, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 5 EP 13 DI 10.1016/0094-5765(92)90004-3 PG 9 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300003 ER PT J AU LUM, H LAU, S AF LUM, H LAU, S TI OPEN ARCHITECTURE SYNTHESIS FOR INTELLIGENT SYSTEMS (OASIS) SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB The implementation of expert systems technologies in aerospace and commercial applications has increased significantly over the last three to five years with cost-effective returns on the original investment. Development efforts are now underway to increase the robustness of expert systems by extending their capabilities through direct interaction with other expert systems, an interactive process described in this paper as cooperating, intelligent systems. Development and implementation of cooperating intelligent systems necessitate a long-term evolutionary approach with critical emphasis placed on the associated hardware and software computational infrastructure. More attention is being paid to the development of standards and interfaces which support an open computational environment, i.e., an environment that is vendor-independent in both hardware and software. This paper discusses the concepts and preliminary results for the Open Architecture Synthesis for Intelligent Systems (OASIS) Testbed which will allow an evolutionary growth with minimum impact to the existing hardware and software environment. Space Station Freedom's Data Management System (DMS) was used as the application focus for the evaluation of the OASIS concepts. RP LUM, H (reprint author), NASA,AMES RES CTR,DIV INFORMAT SCI,MOFFETT FIELD,CA 94035, USA. NR 0 TC 1 Z9 1 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 23 EP 29 PG 7 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300005 ER PT J AU GABRIS, EA AF GABRIS, EA TI UNITED-STATES COMMITMENT TO HEAVY LIFT LAUNCH VEHICLES SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB Observers of the United States' space program will note Progress toward the development of a new launch system capable of supporting the nation's future space missions. The process of defining mission requirements, developing technically and politically acceptable solutions, making policy decisions, and developing budget support in a democratic society is protracted, but eventually yields decisions that represent the public interest. The consensus developing within the United States on a new launch capability including heavy-lift is embodied in the Joint NASA/DoD National Launch System. This launch vehicle concept has emerged after more than five years of studies by NASA, the DoD and every major industrial aerospace contractor in the U.S. In July 1991, Vice President Quayle, in his capacity as Chairman of the National Space Council stated the Nation's commitment to support of the NLS. This paper reviews progress to date, and the involvement of the four major constituencies; the Executive Branch operating through the National Space Council, the Legislative Branch, the various elements of the DoD, and NASA. The evolution of launch system "requirements", along with the form, content and rationale for the various decisions that have been made will be described and discussed. RP GABRIS, EA (reprint author), NASA,HEAVY LIFT LAUNCH VEHICLE PROGRAM,CODE MD,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 91 EP 98 DI 10.1016/0094-5765(92)90013-9 PG 8 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300012 ER PT J AU SCHNEIDER, SJ AF SCHNEIDER, SJ TI HIGH-TEMPERATURE THRUSTER TECHNOLOGY FOR SPACECRAFT PROPULSION SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB A technology program has been underway since 1985 to develop high temperature oxidation-resistant thrusters for spacecraft applications. The successful development of this technology will provide the basis for the design of higher performance satellite engines with reduced plume contamination. Alternatively, this technology program will provide a material with high thermal margin to operate at conventional temperatures and provide increased life for refuelable or reusable spacecraft. The new chamber material consists of a rhenium substrate coated with iridium for oxidation protection. This material increases the operating temperature of thrusters to 2200-degrees-C, a significant increase over the 1400-degrees-C of the silicide-coated niobium chambers currently used. Stationkeeping class 22 N engines fabricated from iridium-coated rhenium have demonstrated steady state specific impulses 20 to 25 seconds higher than niobium chambers. Ir-Re apogee class 440 N engines are expected to deliver an additional 10 to 15 seconds. These improved performances are obtained by reducing or eliminating the fuel film cooling requirements in the combustion chamber while operating at the same overall mixture ratio as conventional engines. The program is attempting to envelope flight qualification requirements to reduce the potential risks and costs of flight qualification programs. RP SCHNEIDER, SJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 5 Z9 6 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 115 EP 125 DI 10.1016/0094-5765(92)90016-C PG 11 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300015 ER PT J AU NICHOLS, DA CURLANDER, JC AF NICHOLS, DA CURLANDER, JC TI EARTH OBSERVING SAR DATA-PROCESSING SYSTEMS AT THE JET PROPULSION LABORATORY - SEASAT TO EOS SAR SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB This paper traces the evolution of SAR digital data processing and management systems developed at JPL for earth science missions. The Interim Digital Processor (IDP) was developed for SEASAT SAR, utilizing a general-purpose mini-computer and commercial array processors. The IDP established the fundamental algorithms for SAR data correlation but performance was inadequate for an extended mission. To increase performance, JPL undertook a research program to develop the Advanced Digital SAR Processor (ADSP) which implemented a frequency-domain correlation algorithm in custom hardware and was capable of processing 50 megabits per second. The ADSP design was subsequently used in a lower-throughput system recently installed at the University of Alaska, Fairbanks. The SIR-C and RADARSAT missions, however, will employ SAR processors based, to the maximum extent possible, on general-purpose, commercially-available computing components. Beginning with the European Earth Resources Satellite (ERS-1), routine geophysical products will be made from SAR data. A prototype system was installed at the Alaska SAR Facility which will routinely generate ice motion and ice type maps. The SIR-C ground processing system and the Alaska SAR Facility are important precursors for EOS SAR, which will have an order of magnitude greater processing requirements. RP NICHOLS, DA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 147 EP 157 DI 10.1016/0094-5765(92)90020-J PG 11 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300019 ER PT J AU SRINIVAS, R LEE, KN SCHAEFER, DA AF SRINIVAS, R LEE, KN SCHAEFER, DA TI CRYSTAL-GROWTH FURNACE - AN OVERVIEW OF THE SYSTEM CONFIGURATION AND PLANNED EXPERIMENTS ON THE 1ST UNITED-STATES MICROGRAVITY LABORATORY MISSION SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB The Crystal Growth Furnace (CGF), currently in the Level IV integration cycle at Kennedy Space Center (KSC) in preparation for its maiden flight on the First United States Microgravity Laboratory (USML-1) mission to be launched in May 1992, has been developed for the National Aeronautics and Space Administration (NASA) under the Microgravity Science and Application Division (MSAD) programs at NASA Headquarters. The project is being managed by the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, under contract NAS8-36637. This paper presents an overview of CGF system description and the system configuration for the USML-1 mission and also briefly describes the planned on-orbit experiments. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP SRINIVAS, R (reprint author), TELEDYNE BROWN ENGN INC,,HUNTSVILLE,AL 35807, USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 227 EP 238 DI 10.1016/0094-5765(92)90026-F PG 12 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300025 ER PT J AU GERSHMAN, R RAYMAN, MD SHAO, M AF GERSHMAN, R RAYMAN, MD SHAO, M TI A MODERATE SPACE MISSION FOR OPTICAL INTERFEROMETRY SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB The Orbiting Stellar Interferometer (OSI) is a proposed space-based observatory which will open exciting new vistas in astronomy and address fundamental scientific questions by making extremely accurate (3 - 30 microarcsecond) astrometric measurements of the positions of-stars, quasars, and other astronomical objects as faint as magnitude 20. In addition, it will be able to image objects with a resolution of 5 milliarcseconds. As the first optical interferometer in space, OSI will provide major advances in astrophysics while demonstrating a powerful concept applicable to major space-based observatories of the future. The Jet Propulsion Laboratory has developed a preliminary design of OSI to establish its feasibility and to estimate performance that can be achieved in a mission of moderate scale. In this first publication of the results of the first year of study, the science objectives are presented, and the design of the mission, instrument, and spacecraft are discussed. RP GERSHMAN, R (reprint author), NASA,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 239 EP 247 DI 10.1016/0094-5765(92)90027-G PG 9 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300026 ER PT J AU CUNNINGHAM, GE ALBEE, AL THORPE, TE AF CUNNINGHAM, GE ALBEE, AL THORPE, TE TI MARS OBSERVER AS A PRECURSOR TO INTENSIVE EXPLORATION OF MARS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB The Mars Observer Mission, to be launched by the United States in September 1992, is designed to perform an extended orbital study of the martian surface, atmosphere, climate, and gravitational and magnetic fields, using a spacecraft in Mars orbit for one martian year. This information will add to the global data base that is necessary for increasing scientific understanding of Mars, as well as for planning the next stages of intensive exploration of the planet. Future missions will progress from more specific robotic exploration to eventual human exploration, and will require progressively more detailed engineering information. Mars observer will provide key basic data -- planet shape, gravity field, geodetic framework, topography, characteristics of the surface, atmospheric profiles, dust content of the atmosphere, wind fields, etc. Special data products for engineering purposes could be obtained from the currently planned data return. Additional engineering data could be returned by augmentation to the basic Mars observer's operation, either in the prime mission or during an extended mission. In particular, the high resolution (1.4 meter/pixel) image coverage could be greatly increased and targeted to specific subjects of interest. Mars Observer will provide a significant contribution to the initiation of intensive mars exploration. RP CUNNINGHAM, GE (reprint author), JET PROP LAB,MARS OBSERV PROJECT,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 259 EP 275 DI 10.1016/0094-5765(92)90029-I PG 17 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300028 ER PT J AU NEWTON, GP AF NEWTON, GP TI LESSONS LEARNED FROM AND THE FUTURE FOR NASA SMALL EXPLORER PROGRAM SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB NASA started the Small Explorer (SMEX) Program to provide space scientists with an opportunity to conduct space science research in the Explorer Program using scientific payloads launched on small-class expendable launch vehicles. A series of small payload, scientific missions was envisioned that could be launched at the rate of one to two missions per year. The missions were to have development periods of approximately three years and cost, on average, less than $30M in Fiscal Year 1988 dollars. Through an Announcement of Opportunity (A.O.) three missions were selected in April 1989: Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX), Fast Auroral Snapshot Explorer (FAST), and Sub-millimeter Wave Astronomy (SWAS). These missions are planned for launch in June 1992, September 1994 and June 1995 respectively. At a program level, this paper presents the history, objectives, status, and lessons learned which may be applicable to similar programs, and discusses future program plans. RP NEWTON, GP (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 307 EP 318 DI 10.1016/0094-5765(92)90034-G PG 12 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300033 ER PT J AU CLINE, LFH ROSENDHAL, JD AF CLINE, LFH ROSENDHAL, JD TI AN ASSESSMENT OF PROSPECTS FOR INTERNATIONAL-COOPERATION ON THE SPACE EXPLORATION INITIATIVE SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND INTERNATIONAL ASTRONAUTICAL FEDERATION CONGRESS ON THE NEXT CENTURY : PROSPECTS FOR SPACE CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB This paper discusses: the unique characteristics of the Space Exploration Initiative (SEI) which will have to be taken into account if the Initiative is to become an international one; the technical capabilities offered by prospective international partners; the political and economic prospects for proceeding with the Initiative both in the United States and elsewhere; the advantages and disadvantages of various possible approaches to international cooperation on SEI; and some of the key issues which will have to be resolved if SEI is to become an international activity. International participation in SEI appears to be a very natural extension of prior space cooperation. There are common interests with a number of potential partners, and a substantial technical capability available outside the United States. However, world-wide political and economic prospects for actually proceeding with the Initiative in the near-term are uncertain. Consequently, SEI preparatory activities are likely to extend over a several-year period. Such an extended preparatory period should provide the time needed for coordinating studies, for identifying interests and potential contributions, and for resolving the numerous planning, budgeting, organizational and political issues which will have to be dealt with if such a complex undertaking is to be successfully internationalized. RP CLINE, LFH (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG PY 1992 VL 28 BP 391 EP 399 DI 10.1016/0094-5765(92)90043-I PG 9 WC Engineering, Aerospace SC Engineering GA JJ103 UT WOS:A1992JJ10300042 ER PT J AU NARAYANSWAMI, N KNIGHT, D BOGDONOFF, SM HORSTMAN, CC AF NARAYANSWAMI, N KNIGHT, D BOGDONOFF, SM HORSTMAN, CC TI INTERACTION BETWEEN CROSSING OBLIQUE SHOCKS AND A TURBULENT BOUNDARY-LAYER SO AIAA JOURNAL LA English DT Article ID SHARP FIN; EQUATIONS; FLOW AB A numerical study of the three-dimensional interaction between crossing shocks generated by symmetric sharp fins and a flat-plate turbulent boundary layer is presented. The full mean compressible Navier-Stokes equations, incorporating a turbulent eddy-viscosity model, are solved. Computed results for the flow past (11 deg, 11 deg) symmetric fins at a freestream Mach number M(infinity) = 2.95 and Reynolds number Re(delta-infinity) = 2.5 x 10(5) (based on the undisturbed boundary-layer thickness delta-infinity) show general agreement with experimental measurements for flat-plate surface pressure and surface flow visualization. Analysis of the computed flowfield reveals a complex interaction involving the "collision" of two slowly counter-rotating vortical structures generated by the initial shock/boundary-layer interaction due to each fin. Associated with the streamline structure of the interaction is the formation and growth of a region of low energy near the centerline, downstream of the crossed shocks. A "first look" at the shock structure of the interaction is provided. C1 PRINCETON UNIV,DEPT MECH & AEROSP ENGN,PRINCETON,NJ 08544. NASA,AMES RES CTR,DEPT MECH & AEROSP ENGN,MOFFETT FIELD,CA 94035. RP NARAYANSWAMI, N (reprint author), RUTGERS STATE UNIV,DEPT MECH & AEROSP ENGN,PISCATAWAY,NJ 08855, USA. NR 23 TC 14 Z9 15 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1992 VL 30 IS 8 BP 1945 EP 1952 DI 10.2514/3.11164 PG 8 WC Engineering, Aerospace SC Engineering GA JG675 UT WOS:A1992JG67500001 ER PT J AU KLEB, WL BATINA, JT WILLIAMS, MH AF KLEB, WL BATINA, JT WILLIAMS, MH TI TEMPORAL ADAPTIVE EULER NAVIER-STOKES ALGORITHM INVOLVING UNSTRUCTURED DYNAMIC MESHES SO AIAA JOURNAL LA English DT Article AB A temporal adaptive algorithm for the time integration of the two-dimensional Euler or Navier-Stokes equations is presented. The flow solver involves an upwind flux-split spatial discretization for the convective terms and central differencing for the shear-stress and heat flux terms on an unstructured mesh of triangles. The temporal-adaptive algorithm is a time-accurate integration procedure that allows flows with high spatial and temporal gradients to be computed efficiently by advancing each grid cell near its maximum allowable time step. Results indicate that an appreciable computational savings can be achieved for both inviscid and viscous unsteady airfoil problems using unstructured meshes without degrading spatial or temporal accuracy. C1 NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,UNSTEADY AERODYNAM BRANCH,HAMPTON,VA 23665. PURDUE UNIV,SCH AERONAUT & ASTRONAUT,W LAFAYETTE,IN 47907. RP KLEB, WL (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 15 TC 18 Z9 21 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1992 VL 30 IS 8 BP 1980 EP 1985 DI 10.2514/3.11169 PG 6 WC Engineering, Aerospace SC Engineering GA JG675 UT WOS:A1992JG67500006 ER PT J AU CELENLIGI, MC MOSS, JN AF CELENLIGI, MC MOSS, JN TI HYPERSONIC RAREFIELD FLOW ABOUT A DELTA WING - DIRECT SIMULATION AND COMPARISON WITH EXPERIMENT SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT 22ND CONF ON FLUID DYNAMICS, PLASMAS DYNAMICS, AND LASERS CY JUN 24-26, 1991 CL HONOLULU, HI SP AMER INST AERONAUT & ASTRONAUT AB Three-dimensional simulations of hypersonic rarefied flow about a delta wing are performed using the direct simulation Monte Carlo method of Bird, and the results of the computations are compared with recent experimental data obtained in a vacuum wind tunnel at the DLR in Gottingen, Germany. The present study considers Mach 8.89 nitrogen now for a range of conditions that include Knudsen numbers of 0.016-3.505 for an incidence angle of 30 deg, and angles of incidence of 15-60 deg for a constant Knudsen number of 0.389. The calculations provide details concerning the flowfield structure and surface quantities. Comparisons between the calculations and the available experimental measurements are made for aerodynamic and overall heat transfer coefficients and recovery temperature. The agreement between the measured and calculated data are very good, well within the estimated measurement uncertainty. Comparisons are also made with modified Newtonian and free-molecule theories. C1 VIGYAN RES ASSOCIATES INC,HAMPTON,VA 23666. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 15 TC 5 Z9 5 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1992 VL 30 IS 8 BP 2017 EP 2023 DI 10.2514/3.11174 PG 7 WC Engineering, Aerospace SC Engineering GA JG675 UT WOS:A1992JG67500011 ER PT J AU WIETING, AR AF WIETING, AR TI MULTIPLE SHOCK-SHOCK INTERFERENCE ON A CYLINDRICAL LEADING-EDGE SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT 22ND CONF ON FLUID DYNAMICS, PLASMAS DYNAMICS, AND LASERS CY JUN 24-26, 1991 CL HONOLULU, HI SP AMER INST AERONAUT & ASTRONAUT AB This Mach 8 study provides the first detailed pressure and heat transfer rate distributions from a two-dimensional shock wave interference pattern created by two incident oblique shock waves intersecting the bow shock wave of a cylinder. The cylinder is representative of the cowl leading edge of a rectangular hypersonic engine inlet. The peak heat transfer rate was 38 times the undisturbed-flow stagnation-point level and occurred when the two oblique shock waves coalesced before intersecting the cylinder bow shock wave. A new shock-shock interference pattern consisting of concomitant supersonic jets separated from each other by a shear layer and submerged in the subsonic region between the bow shock wave and body has been identified. RP WIETING, AR (reprint author), NASA,AMES RES CTR,AEROTHERMAL LOADS BRANCH,MAIL STOP 395,MOFFETT FIELD,CA 94035, USA. NR 15 TC 8 Z9 10 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1992 VL 30 IS 8 BP 2073 EP 2079 DI 10.2514/3.11181 PG 7 WC Engineering, Aerospace SC Engineering GA JG675 UT WOS:A1992JG67500018 ER PT J AU CHEN, FJ MALIK, MR BECKWITH, IE AF CHEN, FJ MALIK, MR BECKWITH, IE TI GORTLER INSTABILITY AND SUPERSONIC QUIET NOZZLE DESIGN SO AIAA JOURNAL LA English DT Article AB To advance boundary-layer stability and transition research and to ultimately provide reliable predictions of transition for supersonic flight vehicles, a wind tunnel is required with very low stream disturbance levels comparable to free-flight conditions. Previous investigations indicated that the freestream noise in pilot quiet nozzles is primarily caused by transition in the nozzle wall boundary layers that are subjected to Gortler instability. A new concept for nozzle design was developed that provides a large increase in the length of the quiet test core by postponing the initiation and decreasing the growth rate of Gortler vortices and thus delays transition on the nozzle walls. A new advanced Mach 3.5 axisymmetric quiet nozzle was fabricated and tested to prove the new design concept. The Reynolds numbers based on the measured length of the quiet test core for this new nozzle are in excellent agreement with the theoretical predictions. C1 HIGH TECHNOL CORP,HAMPTON,VA 23666. GEORGE WASHINGTON UNIV,HAMPTON,VA 23665. RP CHEN, FJ (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 6 TC 7 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1992 VL 30 IS 8 BP 2093 EP 2094 DI 10.2514/3.11184 PG 2 WC Engineering, Aerospace SC Engineering GA JG675 UT WOS:A1992JG67500021 ER PT J AU JACKSON, KE AF JACKSON, KE TI SCALING EFFECTS IN THE FLEXURAL RESPONSE AND FAILURE OF COMPOSITE BEAMS SO AIAA JOURNAL LA English DT Article AB An experimental program was conducted in which scale model graphite-epoxy composite beams were loaded in bending until failure to investigate the effects of specimen size on flexural response and strength. Tests were performed on unidirectional, angle-ply, cross-ply, and quasi-isotropic beams of eight different scaled sizes ranging from 1/6 scale to full scale. The beams were subjected to an eccentric axial compressive load designed to promote large bending deformations and rotations. Results indicated that, although normalized flexural response was independent of specimen size, a significant scale effect in strength was observed for all laminate types. Typically, failure stresses and strains decreased as the size of the beam specimen increased from subscale to the full-scale prototype. Standard failure criteria for composite materials, such as the maximum stress, maximum strain, and tensor polynomial criteria, cannot predict the strength degradation with increasing specimen size. Consequently, a Weibull statistical model and a fracture mechanics model were used to analyze the strength scale effect. RP JACKSON, KE (reprint author), NASA,LANGLEY RES CTR,USA,AEROSTRUCT DIRECTORATE,MAIL STOP 495,HAMPTON,VA 23665, USA. NR 20 TC 16 Z9 16 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1992 VL 30 IS 8 BP 2099 EP 2105 DI 10.2514/3.11186 PG 7 WC Engineering, Aerospace SC Engineering GA JG675 UT WOS:A1992JG67500023 ER PT J AU MCCUAIG, K LLOYD, CW GOSBEE, J SNYDER, WW AF MCCUAIG, K LLOYD, CW GOSBEE, J SNYDER, WW TI SIMULATION OF BLOOD-FLOW IN MICROGRAVITY SO AMERICAN JOURNAL OF SURGERY LA English DT Article ID ERYTHROCYTES AB Knowledge of venous, capillary, and arterial blood flow in microgravity is required to modify hemostatic techniques for control of bleeding in traumatic injuries or surgical procedures in space. To simulate human arterial, venous, and capillary bleeding, fresh whole bovine blood was injected by two operators at calculated flow rates (3.5, 7, and 14 mL for venous and 14 and 28 mL for arterial) in 10 seconds with empirical controls in a lucent glove box during zero gravity parabolic flight on NASA's KC-135 aircraft. A pig's foot was used to mimic capillary bleeding. Hemostasis with sponges and laerdal suction was evaluated by video and still photography. Evaluations of the arterial and venous bleeding were conducted at 3 rates X 3 parabolas, and capillary bleeding was evaluated with 5 parabolas X 2 methods (pig's foot and sponge). Influenced by surface tension, the slow venous bleeding coated syringe surfaces and formed a dome over the skin laceration bleeding site. Arterial and venous bleeders broke into uniform spheres with low-velocity spheres bouncing off an absorbent pad and suction tip. Conventional dabbing with gauze fragmented blood into small spheres. Capillary oozing was better controlled by "wicking" up blood with gauze. Repeated arterial bleeding opacified the glove box wall. This simulation demonstrated unique characteristics of extracorporeal blood flow and inadequacies of common methods of hemostasis in microgravity. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP MCCUAIG, K (reprint author), UNIV ALBERTA,FAC MED,DEPT SURG,DIV GEN SURG,2D WALTER MACKENZIE CTR,8440 112 ST,EDMONTON T6H 2B7,ALBERTA,CANADA. NR 14 TC 12 Z9 12 U1 0 U2 1 PU CAHNERS PUBL CO PI NEW YORK PA 249 WEST 17 STREET, NEW YORK, NY 10011 SN 0002-9610 J9 AM J SURG JI Am. J. Surg. PD AUG PY 1992 VL 164 IS 2 BP 119 EP 123 DI 10.1016/S0002-9610(05)80368-X PG 5 WC Surgery SC Surgery GA JG680 UT WOS:A1992JG68000008 PM 1636890 ER PT J AU DECKER, AJ AF DECKER, AJ TI SELF-ALIGNING OPTICAL MEASUREMENT SYSTEMS SO APPLIED OPTICS LA English DT Note DE ALIGNMENT; METROLOGY; NEURAL NETWORKS; ADAPTIVE OPTICS AB A paradigm is presented for automating the alignment of the components of optical measurement systems and is tested on a spatial filter. RP DECKER, AJ (reprint author), NASA,LEWIS RES CTR,OPT MEASUREMENT SYST BRANCH 771,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 5 TC 2 Z9 2 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 1 PY 1992 VL 31 IS 22 BP 4339 EP 4340 PG 2 WC Optics SC Optics GA JF914 UT WOS:A1992JF91400005 PM 20725422 ER PT J AU MALUMUTH, EM KRISS, GA DIXON, WV FERGUSON, HC RITCHIE, C AF MALUMUTH, EM KRISS, GA DIXON, WV FERGUSON, HC RITCHIE, C TI DYNAMICS OF CLUSTERS OF GALAXIES WITH CENTRAL DOMINANT GALAXIES .1. GALAXY REDSHIFTS SO ASTRONOMICAL JOURNAL LA English DT Article ID X-RAY-CLUSTERS; RICH CLUSTERS; VELOCITY DISPERSIONS; MORPHOLOGICAL TYPES; MULTIPLE-NUCLEI; POOR CLUSTERS; COMA CLUSTER; SUBSTRUCTURE; ANISOTROPY; MASSES AB As part of a study of the dynamical properties of rich clusters with central, dominant D or cD galaxies, we present optical redshifts for a sample of 638 galaxies in the fields of the clusters Abell 85, DC 0107-46, Abell 496, Abell 2052, and DC 1842 - 63. The velocity histograms and wedge diagrams show evidence for a foreground sheet of galaxies in Abell 85 and background sheets of galaxies in DC 0107-46 and Abell 2052. We have used both the Dressler and Shectman and West and Bothun statistical tests for substructure. We confirm the foreground group projected against the center of Abell 85 found by Beers et al. (199 1). We also find significant evidence for substructure in DC 0107-46. We find no evidence of substructure in Abell 496, Abell 2052, and DC 1842 - 63. The clusters have global velocity dispersions ranging from 551 km s-1 for DC 1842-63 to 714 km s-1 for A496, and flat dispersion profiles. Mass estimates using the virial theorem and the projected mass method range from 2.3 X 10(14) M. for DC 0107-46 to 1.1 X 10(15) M. for A85. The velocity of the cD galaxy in each of these clusters with respect to the cluster's velocity ranges from 69 km s-1 for A496 to 390 km s-1 for A85. When combined with an additional 17 clusters from the literature, cD galaxy peculiar velocities show a positive correlation with Abell richness and with cluster velocity dispersion. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAMS,GHRS SCI TEAM,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,HENRY A ROWLAND DEPT PHYS & ASTRON,CTR ASTROPHYS SCI,BALTIMORE,MD 21218. UNIV CAMBRIDGE,INST ASTRON,THE OBSERV,CAMBRIDGE CB3 0HA,ENGLAND. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NR 48 TC 84 Z9 85 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1992 VL 104 IS 2 BP 495 EP 530 DI 10.1086/116250 PG 36 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF142 UT WOS:A1992JF14200001 ER PT J AU FESEN, RA KWITTER, KB DOWNES, RA AF FESEN, RA KWITTER, KB DOWNES, RA TI H-ALPHA IMAGES OF THE CYGNUS LOOP - A NEW LOOK AT SHOCK-WAVE DYNAMICS IN AN OLD SUPERNOVA REMNANT SO ASTRONOMICAL JOURNAL LA English DT Article ID EINSTEIN OBSERVATIONS; OPTICAL-EMISSION; INTERSTELLAR-MEDIUM; HIGH-VELOCITY; CLOUDS; SPECTRUM; VIEW; NOVA; GAS AB Deep Ha images of portions of the east, west, and southwest limbs of the Cygnus Loop are presented which illustrate several aspects of shock dynamics in a multiphase interstellar medium. An Ha image of an isolated eastern shocked cloud reveals cloud deformation and gas stripping along the cloud's edges, shock front diffraction and reflection around the rear of the cloud, and interior remnant emission due to upstream shock reflection. A faint Balmer-dominated filament is identified 30' further west of the remnant's bright line of western radiative filaments (NGC 6960). This detection indicates a far more westerly intercloud shock front position than previously realized, and resolves the nature of the weak x-ray, optical, and nonthermal radio emission observed west of NGC 6960. Strongly caved Balmer-dominated filaments along the remnant's west and southwestern edge may indicate shock diffraction caused by shock wave passage in between clouds. C1 WILLIAMS COLL,THOMSON PHYS & ASTRON LAB,DEPT ASTRON,WILLIAMSTOWN,MA 01267. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP FESEN, RA (reprint author), DARTMOUTH COLL,DEPT PHYS & ASTRON,6127 WILDER LAB,HANOVER,NH 03755, USA. NR 38 TC 31 Z9 31 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1992 VL 104 IS 2 BP 719 EP & DI 10.1086/116267 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF142 UT WOS:A1992JF14200018 ER PT J AU LINFIELD, RP AF LINFIELD, RP TI OCCULATION OF A COMPACT RADIO-SOURCE BY VENUS SO ASTRONOMICAL JOURNAL LA English DT Article ID NIGHTSIDE IONOSPHERE; INTERFEROMETRY; POSITIONS AB An occultation of the compact radio source P0507 + 17 by Venus on 1988 July 19 was observed in Tidbinbilla, Australia at a frequency of 2.3 GHz. The purpose of this observation was to measure the position of Venus in the radio reference frame. When data from both ingress (Venus day side) and egress (Venus night side) were used to solve for the position of Venus in ecliptic longitude and latitude, the results were consistent with zero offsets from the nominal values, with an uncertainty of approximately 0.2" in both coordinates. By using the night-side data alone, a value of -0.026" +/- 0.04" was obtained for the linear combination DELTA-lambda + 0.51-DELTA-beta, where DELTA-lambda and DELTA-beta were the offsets of the ecliptic longitude and latitude of Venus from their nominal values. Distortion of a vacuum Fresnel fringe pattern by the Venus troposphere and especially by the Venus ionosphere was observed. The day-side ionosphere of Venus caused very large distortions; the amplitude of the first Fresnel fringe in the ingress data was 8 times larger than expected for an airless planet. The observed fringe patterns were modeled using plausible ionospheres (i.e., consistent with spacecraft measurements of the Venus ionosphere and with solar extreme ultraviolet flux and solar wind pressure measurements at the occultation epoch). However, the range of Venus ionospheric profiles (electron density as a function of altitude) allowed by a priori constraints and by the occultation data was large (e.g., the ionopause height on the day side was uncertain by a factor of 2). This ionospheric uncertainty (particularly on the day side) translated into a large position uncertainty (0.2" for the day side and 0.04" for the night side). If it had been possible to calibrate the Venus ionosphere by some external means, the accuracy in DELTA-lambda and DELTA-beta would have been 0.01" or better. RP LINFIELD, RP (reprint author), JET PROP LAB,238-700,PASADENA,CA 91109, USA. NR 31 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1992 VL 104 IS 2 BP 880 EP 890 DI 10.1086/116282 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF142 UT WOS:A1992JF14200033 ER PT J AU FEY, AL RUSSELL, JL MA, C JOHNSTON, KJ ARCHINAL, BA CARTER, MS HOLDENRIED, ER YAO, Z DEVEGT, C ZACHARIAS, N AF FEY, AL RUSSELL, JL MA, C JOHNSTON, KJ ARCHINAL, BA CARTER, MS HOLDENRIED, ER YAO, Z DEVEGT, C ZACHARIAS, N TI A RADIO OPTICAL REFERENCE FRAME .4. ADDITIONAL RADIO-SOURCE POSITIONS IN THE NORTHERN-HEMISPHERE SO ASTRONOMICAL JOURNAL LA English DT Article ID VLBI; INTERFEROMETRY; CATALOG AB Seventy-seven extragalactic radio sources north of -2-degrees declination have been observed using Mark III Very-Long Baseline Interferometry during 13 experiments from 1988 October to 1989 November. Radio positions derived from these observations supplement an ongoing project to define and maintain an all-sky radio/optical reference frame of 400 or more extragalactic sources with milliarcsecond (mas) accurate radio and optical positions. Positions for 11 new sources are presented along with improved positions for 54 sources already in the reference-frame catalog. An additional five sources have been determined to be unsuitable reference-frame objects. Observations of seven calibration sources tie the new positions to the existing catalog. The radio positions of the new sources have for-mal mean errors of approximately 0.7 mas in each coordinate. Sources for which we report improved positions now have formal errors less-than-or-equal-to 1 mas, an improvement in some cases by as much as 85%. The complementary optical program is addressed briefly. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. APPL RES CORP,LANDOVER,MD 20785. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. USN OBSERV,WASHINGTON,DC 20390. UNIV HAMBURG,HAMBURGER STERNWARTE,W-2000 HAMBURG 13,GERMANY. RP FEY, AL (reprint author), USN,RES LAB,CODE 4210,WASHINGTON,DC 20375, USA. RI Ma, Chopo/D-4751-2012 NR 10 TC 16 Z9 16 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1992 VL 104 IS 2 BP 891 EP 896 DI 10.1086/116283 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF142 UT WOS:A1992JF14200034 ER PT J AU WILSON, TL MAUERSBERGER, R LANGER, WD GLASSGOLD, AE WILSON, RW AF WILSON, TL MAUERSBERGER, R LANGER, WD GLASSGOLD, AE WILSON, RW TI THE ((CO)-C-12/(CO)-C-13) RATIO TOWARD ZETA OPHIUCHI SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ABUNDANCES IN THE INTERSTELLAR MEDIUM; INTERSTELLAR MOLECULES; ZETA OPH CLOUD ID INTERSTELLAR CLOUDS; ISOTOPE FRACTIONATION; CARBON-MONOXIDE; CO AB A tentative detection of the J=1-0 emission line of (CO)-C-13 has been obtained with SEST from a 24.4 hour integration. The velocity resolution used was 0.23 km s-1 and the FWHP beamwidth was 45". If the (CO)-C-13 line data are conservatively interpreted as an upper limit, the (CO)-C-12/(CO)-C-13 ratio is greater-than-or-equal-to 60. Our result supports the previous determination of a large value of the isotope ratio in this cloud, made using radio emission lines with a 1.6' beam, and extends the ratio based on emission lines to a smaller region. When interpreted as a lower limit, our data is consistent with the ratio obtained from UV absorption line data for (CO)-C-12 and (CO)-C-13. C1 IRAM, E-18012 GRANADA, SPAIN. JET PROP LAB, PASADENA, CA 91109 USA. UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. NYU, DEPT PHYS, NEW YORK, NY 10003 USA. AT&T BELL LABS, HOLMDEL, NJ 07733 USA. RP WILSON, TL (reprint author), MAX PLANCK INST RADIOASTRON, AUF DEM HUGEL 69, W-5300 BONN 1, GERMANY. NR 24 TC 13 Z9 13 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG PY 1992 VL 262 IS 1 BP 248 EP 250 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JK482 UT WOS:A1992JK48200029 ER PT J AU SHAO, M COLAVITA, MM AF SHAO, M COLAVITA, MM TI POTENTIAL OF LONG-BASE-LINE INFRARED INTERFEROMETRY FOR NARROW-ANGLE ASTROMETRY SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ASTROMETRY; TECHNIQUES; INTERFEROMETRIC; ATMOSPHERIC EFFECTS ID III STELLAR INTERFEROMETER; ATMOSPHERIC LIMITATIONS; TURBULENCE AB Narrow-angle astrometry has many astrophysical applications, from the measurement of parallaxes to the search for planets around nearby stars. Ground-based long-focus telescopes with photoelectric detectors have achieved accuracies of approximately 2-3 milliarcsec in 1 h. This accuracy is limited primarily by the atmosphere, and is consistent with models of atmospheric turbulence. However, applying these turbulence models to observations with long-baseline interferometers yields astrometric errors that are far smaller than can be achieved with long-focus telescopes. The predictions for the ultimate accuracy of ground-based narrow-angle astrometry using long-baseline infrared (2.2-mu-m) stellar interferometers are very promising. With the excellent seeing at a high altitude site like Mauna Kea, the atmospheric limit for a 1 h astrometric measurement is expected to be of the order of 10 microarcsec for 1 h of integration. This two-order-of-magnitude improvement over conventional measurements is due to two effects. One is that a long-baseline infrared interferometer can find useful reference stars very near an arbitrary target star, so that the atmospherically-induced motions of both stars are highly correlated. The second is that the baseline length can be much larger than the separation of the stellar beams in the turbulent atmosphere, resulting in a reduction in astrometric error with increasing baseline length. RP SHAO, M (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 26 TC 132 Z9 133 U1 1 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 AUG PY 1992 VL 262 IS 1 BP 353 EP 358 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JK482 UT WOS:A1992JK48200044 ER PT J AU SMITH, BA FOUNTAIN, JW TERRILE, RJ AF SMITH, BA FOUNTAIN, JW TERRILE, RJ TI AN OPTICAL-SEARCH FOR BETA-PICTORIS-LIKE DISKS AROUND NEARBY STARS SO ASTRONOMY & ASTROPHYSICS LA English DT Note DE STARS; CIRCUMSTELLAR MATTER AB A coronagraphic survey of more than one hundred stars has been carried out in a search at optical wavelengths for circumstellar material similar to that found in the beta-Pictoris disk. The survey stars were primarily dwarfs in the spectral range A to K and most were closer than 100 pc. No evidence of circumstellar material was found around any of the stars, suggesting that beta-Pictoris is an abnormal object, surrounded by an unusually large amount of optically scattering material. C1 UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. JET PROP LAB, PASADENA, CA 91101 USA. RP SMITH, BA (reprint author), UNIV HAWAII, INST ASTRON, 2680 WOODLAWN DR, HONOLULU, HI 96822 USA. NR 14 TC 29 Z9 29 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG PY 1992 VL 261 IS 2 BP 499 EP 502 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH740 UT WOS:A1992JH74000020 ER PT J AU VANBUREN, D MACLOW, MM AF VANBUREN, D MACLOW, MM TI BOW SHOCK-MODELS FOR THE VELOCITY STRUCTURE OF ULTRACOMPACT-H-II REGIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE H-II REGIONS; HYDRODYNAMICS; ISM, INDIVIDUAL (G29.9-0.02); ISM, KINEMATICS AND DYNAMICS; SHOCK WAVES AB We model the velocity structure of ultracompact H II regions assuming that 0 stars moving supersonically through molecular clouds sweep up bow shocks to produce the observed objects. We calculate the expected radio recombination line emission for the case of an optically thin continuum and show the strong effect of changing the viewing angle. The kinematic information removes the degeneracy with ram pressure of our previous model, allowing measurement of stellar velocity vectors and cloud densities. A detailed model for G29.96 - 0.02 shows good agreement with observations by Wood and Churchwell, supporting the bow shock hypothesis. We find that the exciting star of G29 is moving at 20 km s-1 relative to the gas, suggesting that O stars acquire a large velocity dispersion early in their lives. C1 JET PROP LAB,PASADENA,CA 91109. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR STAR FORMAT,BERKELEY,CA 94720. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP VANBUREN, D (reprint author), CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125, USA. OI Mac Low, Mordecai-Mark/0000-0003-0064-4060 NR 10 TC 58 Z9 58 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1992 VL 394 IS 2 BP 534 EP 538 DI 10.1086/171604 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JE712 UT WOS:A1992JE71200015 ER PT J AU BIGGS, JD AF BIGGS, JD TI AN ANALYSIS OF RADIO PULSAR NULLING STATISTICS SO ASTROPHYSICAL JOURNAL LA English DT Article DE PULSARS, GENERAL ID POLARIZATION CHARACTERISTICS; SOUTHERN PULSARS; EMPIRICAL-THEORY; EMISSION; DRIFT AB We have sought correlations between the fraction of null pulses and' other pulsar characteristics for an ensemble of 72 radio pulsars using survival analysis methods. The strongest correlation was found between the null fraction and pulse period. This suggests that nulling is a manifestation of a faltering emission mechanism since many parameters of importance to polar cap models of pulsar emission have an inverse dependence on pulse period. Correlations were also found between the fraction of null pulses and other parameters that have a strong dependence on pulse period. In particular, a correlation (of marginal significance) was found between pulsar characteristic age and null fraction consistent with the earlier work of Ritchings, but we suggest that this is the result of the strong period dependence in the pulsar characteristic age. Further, a significant anti-correlation was found between the angle subtended by the magnetic and rotation axes, and null fraction. This suggests that nulling may also have a geometric origin. Radio luminosity was also found to be anticorrelated with the null fraction. Many of the pulsars studied here were found to null and there is considerable variation in the fraction of null pulses within each of the pulse profile classes devised by Rankin, but generally class S, pulsars null the least. Furthermore, we found differences between the mean ages of the pulsar classes. This implies that nulling is influenced by pulsar class, but our results suggest that the significance of this effect is lower than that found by Rankin. Of special note is the fact that two pulsars PSR 0833-45 and PSR 1556-44 do not apparently null. The upper limit for PSR 0833-45 is rather low, no nulls being detected in observations of over 120,000 pulses. The similarity of the nulling parameters of pulsars observed at two frequencies (near 400 and 843 MHz) suggests that the pulsar emission mechanism is broad-band over this frequency range. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP BIGGS, JD (reprint author), UNIV SYDNEY,SCH PHYS,SYDNEY,NSW 2006,AUSTRALIA. NR 23 TC 39 Z9 39 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1992 VL 394 IS 2 BP 574 EP 580 DI 10.1086/171608 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JE712 UT WOS:A1992JE71200019 ER PT J AU KLOPMAN, Z EVIATAR, A GOLDSTEIN, R AF KLOPMAN, Z EVIATAR, A GOLDSTEIN, R TI THE FORMATION OF MAGNETIC CAVITIES IN COMETS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COMETS, GENERAL; MHD ID CONTACT SURFACE; INNER COMA; HALLEY; MODEL; P/HALLEY; GAS AB In this paper a unidimensional model for the formation of magnetic cavities in comets is presented. This model includes ion-neutral friction, dissociative recombination, photoionization, and thermal and energetic ion pressure coupled with a nonconstant velocity profile which was chosen to simulate the flow pattern. The model explains the thermal ion population profile. Conditions under which a cavity may not form are discussed. In the paper the roles of the various processes are studied, and it is shown that focusing on ion-neutral friction as the major process in the creation of the cavity is not in general correct. In the last part of the paper, the limitations of the model are delineated. C1 JET PROP LAB,PASADENA,CA 91109. RP KLOPMAN, Z (reprint author), TEL AVIV UNIV,RAYMOND & BEVERLY SACKLER FAC EXACT SCI,IL-69978 TEL AVIV,ISRAEL. NR 23 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1992 VL 394 IS 2 BP 652 EP 661 DI 10.1086/171619 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JE712 UT WOS:A1992JE71200030 ER PT J AU BRAINERD, JJ AF BRAINERD, JJ TI SYNCHROTRON EMISSION FROM A COSMOLOGICAL JET AS A MODEL OF GAMMA-RAY BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS; BURSTS ID ABSORPTION; FEATURES AB The non-thermal, rapidly varying spectra of gamma-ray bursts require relativistic beaming if the source is at a cosmological distance. Limits on the Lorentz factors and magnetic fields of extragalactic jet models of gamma-ray bursts are derived from the synchrotron source function, the position of the fundamental cyclotron resonance, the Thomson optical depth of radiating electrons, and the Thomson optical depth of electron-positron pairs created in photon-photon collisions of Compton upscattered radiation. The last of these constraints is the strongest, and it is satisfied by the observations if the jet's Lorentz factor is greater than 100. The limit from the position of the cyclotron fundamental requires a magnetic field strength below almost-equal-to 10(10) G. Jet models producing observable cyclotron lines are allowed. The acceleration region in the burst must be separate from the emission region. The similarity of gamma-ray burst jet models to models of quasars and BL Lac objects suggest that if gamma-ray bursts are cosmological sources, they are a type of active galaxy. RP BRAINERD, JJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-65,HUNTSVILLE,AL 35812, USA. NR 14 TC 17 Z9 17 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1992 VL 394 IS 2 BP L33 EP L36 DI 10.1086/186466 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JE714 UT WOS:A1992JE71400001 ER PT J AU DUDLEY, GA DUVOISIN, MR ADAMS, GR MEYER, RA BELEW, AH BUCHANAN, P AF DUDLEY, GA DUVOISIN, MR ADAMS, GR MEYER, RA BELEW, AH BUCHANAN, P TI ADAPTATIONS TO UNILATERAL LOWER-LIMB SUSPENSION IN HUMANS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID RAT SKELETAL-MUSCLE; HUMAN MOTOR UNITS; BED REST; IMMOBILIZATION; STRENGTH; ATROPHY; TORQUE; VOLUNTARY; VELOCITY; FATIGUE AB This study examined the effect of unilateral lower limb suspension (ULLS) on neuromuscular function in humans. Eight subjects (31 +/- 4 years old) performed all ambulatory activity on crutches for 6 weeks while wearing a shoe with o 10-cm sole on the right foot to unweight the left lower limb. Knee extensor (KE) torque during eccentric, concentric, and isometric actions, and electromyography (EMG) of m. vastus lateralis (m. VL), m. gastrocnemius medialis (m. GM) and m. soleus (m. SL) during isometric actions were assessed pre-ULLS, post-ULLS, and after 4 d of recovery. Average muscle cross-sectional area (CSA) of the KE was measured pre- and post-ULLS and that of the ankle extensors (AE) post-ULLS using magnetic resonance imaging. Strength of the KE of the suspended left limb was reduced (p < 0.05) 21 and 15%, respectively, after ULLS and 4 d later. Average muscle CSA of the left KE decreased (p < 0.05) 16%. The KE of the non-suspended right limb showed no changes in muscLe CSA. Thus, Average muscle CSA of the KE of the suspended limb was 17% less (p < 0.05) than that of the non-suspended limb. Average muscle CSA of the AE, likewise, was smalLer (18%, p < 0.05) in the left than right leg after ULLS. Maximal integrated EMG of VL and overalL mean power frequency of GM and SL for submaximaL isometric actions were both decreased (p < 0.05) post-ULLS. Taken together, the results indicate that 6 weeks of ULLS induces adaptations in the neuromuscular system of humans which are comparable to those induced by bed rest and spaceflight. C1 BIONET CORP,BIOMED & ENVIRONM LABS,KENNEDY SPACE CTR,FL. HOLMES REG MED CTR,MAGNET RESONANCE IMAGING,MELBOURNE,FL. MICHIGAN STATE UNIV,DEPT PHYSIOL,E LANSING,MI 48824. MICHIGAN STATE UNIV,DEPT RADIOL,E LANSING,MI 48824. RP DUDLEY, GA (reprint author), NASA,BIOMED OPERAT & RES OFF,MAIL CODE MD-M,KENNEDY SPACE CTR,FL 32899, USA. NR 27 TC 79 Z9 79 U1 0 U2 5 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD AUG PY 1992 VL 63 IS 8 BP 678 EP 683 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JH361 UT WOS:A1992JH36100004 PM 1510640 ER PT J AU NAZAR, K GREENLEAF, JE POHOSKA, E TURLEJSKA, E KACIUBAUSCILKO, H KOZLOWSKI, S AF NAZAR, K GREENLEAF, JE POHOSKA, E TURLEJSKA, E KACIUBAUSCILKO, H KOZLOWSKI, S TI EXERCISE PERFORMANCE, CORE TEMPERATURE, AND METABOLISM AFTER PROLONGED RESTRICTED ACTIVITY AND RETRAINING IN DOGS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID BED REST; GLUCOSE; LIPOLYSIS; INSULIN AB To study physiological effects of restricted activity (RA) and subsequent retraining, 10 male mongrel dogs (1-5 years) performed a submaximal exercise endurance test on a treadmill (12-degrees slope, 1.6 m . s-1) during kennel control, after 8 weeks of cage (40 cm-w x 80 cm-h x 110 cm-l) confinement, and after 8 weeks of retraining using the same treadmill protocol 1 h/d for 6 d/week. Compared with control endurance (172 +/- 19 min), endurance decreased to 102 +/- 15 min (DELTA=-41%, p < 0.05) after RA and increased to 223 +/- 24 min (DELTA=+30%, p < 0.05) after training: the respective final levels and changes in rectal temperature were 41.25 and +2.15-degrees-C, 41.60 and +2.70-degrees-C (NS), and 41.35 and +2.40-degrees-C (NS), respectively. Resting and post-exercise blood glucose and lactate concentrations were unchanged in the three experiments. After RA, resting muscle glycogen was reduced from a control level of 49.9 +/- 4.3 to 34.1 +/- 4.5 mmol . kg-1 (DELTA=32%, p < 0.05) which returned to the control level of 58.4 +/- 3.5 mmol . kg-1 after retraining. Resting plasma FFA levels were unchanged, but the RA post-exercise change was decreased from a control level of +0.400 +/- 0.099 to +0.226 +/- 0.039 mmol . L-1 (p < 0.05). Neither restricted activity nor training affected glucose tolerance significantly. The results indicated that RA reduces exercise endurance, the effectiveness of exercise thermoregulation, muscle glycogen stores, and the lipolytic response to exercise and to noradrenaline stimulation. All these changes were reversed following 8 weeks of retraining. C1 NASA,AMES RES CTR,DIV LIFE SCI 23911,HUMAN GRAVITAT PHYSIOL LAB,MOFFETT FIELD,CA 94035. POLISH ACAD SCI,MED RES CTR,DEPT APPL PHYSIOL,WARSAW 42,POLAND. NR 22 TC 7 Z9 7 U1 0 U2 5 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD AUG PY 1992 VL 63 IS 8 BP 684 EP 688 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JH361 UT WOS:A1992JH36100005 PM 1510641 ER PT J AU ACKMAN, RG TAKEUCHI, T BALAZS, GH AF ACKMAN, RG TAKEUCHI, T BALAZS, GH TI FATTY-ACIDS IN DEPOT FATS OF GREEN TURTLES CHELONIA-MYDAS FROM THE HAWAIIAN-ISLANDS AND JOHNSTON ATOLL SO COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY LA English DT Article ID DERMOCHELYS-CORIACEA; CARETTA-CARETTA; ALLIGATOR-MISSISSIPPIENSIS; SEAGRASS COMMUNITIES; AMERICAN ALLIGATOR; LIPID-COMPOSITION; FOOD-CHAINS; FISH OILS; LOGGERHEAD; NUTRITION AB 1. Depot fat samples from thirteen individual mid-Pacific turtles Chelonia mydas were examined for overall fatty acid composition. 2. It can be concluded from analysis of fatty acids that the mid-Pacific green turtles generally synthesize their triglyceride depot fats with at least one, but not more than two, positions occupied by 12:0 and 14:0, possibly with 16:0 and 16:1 as well. 3. These two fatty acids are probably utilized as temporary energy storage and are synthesized from acetate originating in the gut from dietary carbohydrates. 4. The most probable source of dietary carbohydrate is benthic algae. These, their epiphytes, and gut bacteria also contribute numerous minor and trace unsaturated fatty acids. 5. A select group of four oils of high iodine value (> 100) are shown to have a higher than common concentration of 22:6n-3-22:5n-3. This suggests a particular dietary source of fatty acids different from the other samples, possibly including jellyfish or other animal matter. C1 NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU,HI 96822. TOKYO UNIV FISHERIES,FISH NUTR LAB,MINATO KU,TOKYO 108,JAPAN. RP ACKMAN, RG (reprint author), TECH UNIV NOVA SCOTIA,CANADIAN INST FISHERIES TECHNOL,BOX 1000,HALIFAX B3J 2X4,NS,CANADA. NR 50 TC 2 Z9 2 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0305-0491 J9 COMP BIOCHEM PHYS B JI Comp. Biochem. Physiol. B-Biochem. Mol. Biol. PD AUG PY 1992 VL 102 IS 4 BP 813 EP 819 DI 10.1016/0305-0491(92)90085-6 PG 7 WC Biochemistry & Molecular Biology; Zoology SC Biochemistry & Molecular Biology; Zoology GA JH263 UT WOS:A1992JH26300025 ER PT J AU ALKALAJ, L LANG, T ERCEGOVAC, MD AF ALKALAJ, L LANG, T ERCEGOVAC, MD TI ARCHITECTURAL SUPPORT FOR GOAL MANAGEMENT IN FLAT CONCURRENT PROLOG SO COMPUTER LA English DT Article C1 UNIV POLITECN CATALUNA,DEPT COMP ARCHITECTURE,CATALUNYA,SPAIN. UNIV CALIF LOS ANGELES,SCH ENGN & APPL SCI,DEPT COMP SCI,LOS ANGELES,CA 90024. RP ALKALAJ, L (reprint author), JET PROP LAB,ROBOT SYST & ADV COMP TECHNOL SECT,ADV FLIGHT COMP GRP,MS 198-219,PASADENA,CA 91109, USA. NR 12 TC 0 Z9 0 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0018-9162 J9 COMPUTER JI Computer PD AUG PY 1992 VL 25 IS 8 BP 34 EP 47 DI 10.1109/2.153282 PG 14 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA JH015 UT WOS:A1992JH01500004 ER PT J AU STOTHERS, RB AF STOTHERS, RB TI IMPACTS AND TECTONISM IN EARTH AND MOON HISTORY OF THE PAST 3800 MILLION YEARS SO EARTH MOON AND PLANETS LA English DT Article ID CONTINENTAL CRUST; FLOOD BASALTS; CRATERS; GROWTH; AGES AB The Moon's surface, unlike the Earth's, displays a comparatively clear record of its past bombardment history for the last 3800 Myr, the time since active lunar tectonism under the massive pre-mare bombardment ended. From Baldwin's tabulation of estimated ages for a representative sample of large lunar craters younger than 3800 Ma, six major cratering episodes can be discerned. These six bombardment episodes, which must have affected the Earth too, appear to match in time the six major episodes of orogenic tectonism on Earth, despite typical resolution errors of +/-100 Myr and the great uncertainties of the two chronologies. Since more highly resolved events during the Cenozoic and Mesozoic Eras suggest the same correlation, it is possible that large impacts have influenced plate tectonics and other aspects of geologic history, perhaps by triggering flood basalt eruptions. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 29 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 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD AUG PY 1992 VL 58 IS 2 BP 145 EP 152 DI 10.1007/BF00054651 PG 8 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA JV986 UT WOS:A1992JV98600004 ER PT J AU PENG, CY IWAN, WD AF PENG, CY IWAN, WD TI AN IDENTIFICATION METHODOLOGY FOR A CLASS OF HYSTERETIC STRUCTURES SO EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS LA English DT Article AB This paper presents a method of identification for determining non-linear dynamic models for certain hysteretic structures. Particular attention is given to modelling and identifying the hysteretic behaviour of structures from strong-motion earthquake data. In this method, the response is separated into mode-like components which are analogous to those of a linear system. Based on modelling of the generalized restoring force of each mode-like component, both non-hysteretic and hysteretic non-linear models are incorporated into the general methodology. A non-hysteretic model provides an initial estimate for a final hysteretic model. The approach is applicable even when data are. available from only a small number of locations in the structure. The structural model identified from this method provides a means to predict the response to future events and, ultimately, to examine the damage to a structure as a result of an earthquake. C1 CALTECH,PASADENA,CA 91125. RP PENG, CY (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 22 TC 27 Z9 27 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0098-8847 J9 EARTHQUAKE ENG STRUC JI Earthq. Eng. Struct. Dyn. PD AUG PY 1992 VL 21 IS 8 BP 695 EP 712 DI 10.1002/eqe.4290210804 PG 18 WC Engineering, Civil; Engineering, Geological SC Engineering GA JH033 UT WOS:A1992JH03300004 ER PT J AU DAVIS, MW OLLA, BL AF DAVIS, MW OLLA, BL TI THE ROLE OF VISUAL CUES IN THE FACILITATION OF GROWTH IN A SCHOOLING FISH SO ENVIRONMENTAL BIOLOGY OF FISHES LA English DT Article DE BEHAVIOR; CHUM SALMON; GROWTH VARIATION; ONCORHYNCHUS-KETA; SENSORY INPUT; VISUAL CONTACT ID SALVELINUS-ALPINUS L; SOCIAL CONSTRAINTS; ARCTIC CHARR; PISCES; BEHAVIOR AB This study tested the hypothesis that visual contact between fish may result in enhanced rates of growth in a schooling fish. Juvenile chum salmon, Oncorhynchus keta, were held singly and reared in isolation or in visual contact with conspecifics. Fish were fed at either a low (6% body weight d-1) or high (20% body weight d-1) ration for 42 d. Specific rates of weight gain were 18% greater at low ration and 38% greater at high ration for fish in visual contact with conspecifics than for those held in isolation. The results demonstrate a selective advantage of visual cues associated with schooling behavior and suggest that the efficacy of growth models for schooling fishes may be enhanced by the consideration of social interactions which may facilitate growth. RP DAVIS, MW (reprint author), HATFIELD MARINE SCI CTR,NATL MARINE FISHERIES SERV,NW & ALASKA FISHERIES CTR,NEWPORT,OR 97365, USA. NR 20 TC 12 Z9 12 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0378-1909 J9 ENVIRON BIOL FISH JI Environ. Biol. Fishes PD AUG PY 1992 VL 34 IS 4 BP 421 EP 424 DI 10.1007/BF00004746 PG 4 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA JE172 UT WOS:A1992JE17200008 ER PT J AU CRENSHAW, AG STYF, JR HARGENS, AR AF CRENSHAW, AG STYF, JR HARGENS, AR TI INTRAMUSCULAR PRESSURES DURING EXERCISE - AN EVALUATION OF A FIBER OPTIC TRANSDUCER-TIPPED CATHETER SYSTEM SO EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY LA English DT Article DE CONCENTRIC EXERCISE; ISOMETRIC EXERCISE; MUSCLE CONTRACTION PRESSURE; MUSCLE RELAXATION PRESSURE; HUMAN TIBIALIS ANTERIOR MUSCLE ID ANTERIOR COMPARTMENT SYNDROME; SKELETAL-MUSCLE; LOWER LEG; CONTRACTION; DIAGNOSIS; BLOOD AB The efficacy of a modified fibre optic transducer-tipped catheter system for measuring intramuscular pressures during exercise was determined. A microcapillary infusion technique using a catheter was employed as the standard of comparison due to its established dynamic properties. Pressures were measured in the tibialis anterior muscle of six healthy adults at rest before exercise, during isometric and concentric exercise, and at rest after exercise. The fibre optic system measured contraction pressures equal to the microcapillary infusion technique during all phases of the exercise protocols but recorded a lower relaxation pressure during isometric exercise and a lower rest pressure following 20 min of concentric exercise. Negative relaxation pressures were recorded by the fibre optic system for two subjects during continuous concentric exercise. It is hypothesized that a piston effect, due to the sliding of muscle fibres at the catheter tip following a contraction, rendered falsely low pressures during relaxation and that this artefact was reflected in the subsequent rest pressure following exercise. The larger volume (157 mm3) and area (3.49 mm2) of the fibre optic catheter in the muscle made it more prone to this effect than the conventional catheter (39 mm3 and 0.87 mm2, respectively). The fibre optic system may be preferred when recording the muscle contraction pressures during complex limb movements but should not be used when assessing the relaxation pressures or the pressure at rest following exercise. C1 GOTHENBURG UNIV,EAST HOSP,DEPT ORTHOPAED,S-41685 GOTHENBURG,SWEDEN. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. RP CRENSHAW, AG (reprint author), UMEA UNIV,DEPT ANAT,S-90187 UMEA,SWEDEN. NR 22 TC 15 Z9 15 U1 0 U2 2 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0301-5548 J9 EUR J APPL PHYSIOL O JI Eur. J. Appl. Physiol. Occup. Physiol. PD AUG PY 1992 VL 65 IS 2 BP 178 EP 182 DI 10.1007/BF00705077 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JH302 UT WOS:A1992JH30200014 PM 1396642 ER PT J AU BOWEN, BW MEYLAN, AB ROSS, JP LIMPUS, CJ BALAZS, GH AVISE, JC AF BOWEN, BW MEYLAN, AB ROSS, JP LIMPUS, CJ BALAZS, GH AVISE, JC TI GLOBAL POPULATION-STRUCTURE AND NATURAL-HISTORY OF THE GREEN TURTLE (CHELONIA-MYDAS) IN TERMS OF MATRIARCHAL PHYLOGENY SO EVOLUTION LA English DT Article ID GENE FLOW; MITOCHONDRIAL-DNA; SEA-TURTLE; RESTRICTION ENDONUCLEASES; ALLELES; CONSERVATION; REPRODUCTION; ATLANTIC; ODYSSEY; GROWTH AB To address aspects of the evolution and natural history of green turtles, we assayed mitochondrial (mt) DNA genotypes from 226 specimens representing 15 major rookeries around the world. Phylogenetic analyses of these data revealed (1) a comparatively low level of mtDNA variability and a slow mtDNA evolutionary rate (relative to estimates for many other vertebrates); (2) a fundamental phylogenetic split distinguishing all green turtles in the Atlantic-Mediterranean from those in the Indian-Pacific Oceans; (3) no evidence for matrilineal distinctiveness of a commonly recognized taxonomic form in the East Pacific (the black turtle C. m. agassizi or C. agassizi); (4) in opposition to published hypotheses, a recent origin for the Ascension Island rookery, and its close genetic relationship to a geographically proximate rookery in Brazil; and (5) a geographic population substructure within each ocean basin (typically involving fixed or nearly fixed genotypic differences between nesting populations) that suggests a strong propensity for natal homing by females. Overall, the global matriarchal phylogeny of Chelonia mydas appears to have been shaped by both geography (ocean basin separations) and behavior (natal homing on regional or rookery-specific scales). The shallow evolutionary population structure within ocean basins likely results from demographic turnover (extinction and colonization) of rookeries over time frames that are short by evolutionary standards but long by ecological standards. C1 UNIV GEORGIA,DEPT GENET,ATHENS,GA 30602. NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. FLORIDA MARINE RES INST,DEPT NAT RESOURCES,ST PETERSBURG,FL 33701. FLORIDA MUSEUM NAT HIST,DEPT NAT SCI,GAINESVILLE,FL 32611. QUEENSLAND NATL PK & WILDLIFE SERV,N QUAY,QLD 4002,AUSTRALIA. NR 96 TC 222 Z9 242 U1 6 U2 78 PU SOC STUDY EVOLUTION PI LAWRENCE PA 810 E 10TH STREET, LAWRENCE, KS 66044 SN 0014-3820 J9 EVOLUTION JI Evolution PD AUG PY 1992 VL 46 IS 4 BP 865 EP 881 DI 10.2307/2409742 PG 17 WC Ecology; Evolutionary Biology; Genetics & Heredity SC Environmental Sciences & Ecology; Evolutionary Biology; Genetics & Heredity GA JK169 UT WOS:A1992JK16900001 ER PT J AU NUTH, JA MOORE, MH TANABE, T KRAUS, G AF NUTH, JA MOORE, MH TANABE, T KRAUS, G TI THE -SIH VIBRATIONAL STRETCH AS AN INDICATOR OF THE OXIDATION-STATE OF SILICON IN A COMETARY OR ASTEROIDAL REGOLITH SO ICARUS LA English DT Article ID INFRARED-ABSORPTION; P/HALLEY; HYDROGEN; SPECTRA; GRAINS C1 CHARLES CTY COMMUNITY COLL,DEPT PHYS SCI,LA PLATA,MD. RP NUTH, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,ASTROCHEM BRANCH,GREENBELT,MD 20771, USA. RI Nuth, Joseph/E-7085-2012 NR 17 TC 9 Z9 9 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1992 VL 98 IS 2 BP 207 EP 210 DI 10.1016/0019-1035(92)90090-T PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JK598 UT WOS:A1992JK59800005 ER PT J AU HARMON, JK SLADE, MA HUDSON, RS AF HARMON, JK SLADE, MA HUDSON, RS TI MARS RADAR SCATTERING - ARECIBO GOLDSTONE RESULTS AT 12.6-CM AND 3.5-CM WAVELENGTHS SO ICARUS LA English DT Article ID SURFACE PROPERTIES; MARTIAN SURFACE; ROCKS C1 JET PROP LAB,PASADENA,CA 91109. WASHINGTON STATE UNIV,PULLMAN,WA 99164. RP HARMON, JK (reprint author), NATL ASTRON & IONOSPHERE CTR,ARECIBO,PR 00613, USA. NR 27 TC 20 Z9 21 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1992 VL 98 IS 2 BP 240 EP 253 DI 10.1016/0019-1035(92)90093-M PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JK598 UT WOS:A1992JK59800008 ER PT J AU LELLOUCH, E BELTON, M DEPATER, I PAUBERT, G GULKIS, S ENCRENAZ, T AF LELLOUCH, E BELTON, M DEPATER, I PAUBERT, G GULKIS, S ENCRENAZ, T TI THE STRUCTURE, STABILITY, AND GLOBAL DISTRIBUTION OF IOS ATMOSPHERE SO ICARUS LA English DT Article ID SO2 ATMOSPHERE; SURFACE; ABUNDANCE; SPECTRUM; METEOROLOGY; IONOSPHERE; VOYAGER-1; PRESSURE; JUPITER; BODIES C1 NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. UNIV CALIF BERKELEY,BERKELEY,CA 94720. INST RADIO ASTRON MILLIMETR,GRANADA,SPAIN. JET PROP LAB,PASADENA,CA 91109. RP LELLOUCH, E (reprint author), OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. NR 69 TC 88 Z9 88 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1992 VL 98 IS 2 BP 271 EP 295 DI 10.1016/0019-1035(92)90095-O PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JK598 UT WOS:A1992JK59800010 ER PT J AU MURTHY, KMS NUSPL, PP RAFFERTY, W KATO, S AF MURTHY, KMS NUSPL, PP RAFFERTY, W KATO, S TI ADVANCES IN SATELLITE-COMMUNICATIONS NETWORKING AND APPLICATIONS .2. SO IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS LA English DT Editorial Material C1 INTELSAT, WASHINGTON, DC 20008 USA. JET PROP LAB, ADV SYST PROGRAM, PASADENA, CA 91109 USA. NIPPON TELEGRAPH & TEL PUBL CORP, YOKOSUKA ELECT COMMUN LABS, RADIO COMMUN SYST LABS, YOKOSUKA, KANAGAWA 23803, JAPAN. UNIV OTTAWA, ELECT ENGN, OTTAWA K1N 6N5, ONTARIO, CANADA. RP MURTHY, KMS (reprint author), TELESAT CANADA, APPLICAT RES & DEV SECT, 1601 TELESAT COURT, GLOUCESTER K1B 5P4, ONTARIO, CANADA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0733-8716 EI 1558-0008 J9 IEEE J SEL AREA COMM JI IEEE J. Sel. Areas Commun. PD AUG PY 1992 VL 10 IS 6 BP 977 EP 978 PG 2 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JC780 UT WOS:A1992JC78000001 ER PT J AU LAY, N DESSOUKY, K AF LAY, N DESSOUKY, K TI A COMMUNICATION PROTOCOL FOR MOBILE SATELLITE SYSTEMS AFFECTED BY RAIN ATTENUATION SO IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS LA English DT Article AB One of the principal challenges to the realization of mobile and personal satellite systems at higher frequencies, such as at K/Ka-band, is the rain attenuation experienced at those frequencies. This paper presents a communication protocol that has been developed as part of a proof of concept K/Ka-band mobile satellite system to be demonstrated with NASA's Advanced Communications Technologies Satellite (ACTS) in 1993. The protocol's objectives are to provide the means for enhancing link availability and continuity by supporting real-time data rate selection and changes during rain events. The protocol is developed with emphasis on being efficient yet robust to the primary channel impairment in such mobile satellite systems, viz., shadowing outages. The system architecture is first briefly presented and the analytical framework from which the protocol originates is pointed out. Link, connection, and packet types are then introduced and the protocol procedures and design rationales discussed. The detailed presentation focuses on link setup with the appropriate data rate(s) and the real-time switching of data rates during a voice conversation to either preserve the link or enhance its quality during rain attenuation events. RP LAY, N (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 16 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0733-8716 J9 IEEE J SEL AREA COMM JI IEEE J. Sel. Areas Commun. PD AUG PY 1992 VL 10 IS 6 BP 1037 EP 1047 DI 10.1109/49.144890 PG 11 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JC780 UT WOS:A1992JC78000008 ER PT J AU BONDYOPADHYAY, PK AF BONDYOPADHYAY, PK TI ANALYSIS OF ROTATIONALLY SYMMETRICAL ARRAYS OF APERTURES ON CONDUCTING SPHERICAL SURFACES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB Rotationally symmetric arrays of circular waveguide fed apertures on conducting spherical surfaces have been analyzed. Representation of the outside electromagnetic fields in terms of spherical transmission line modes permit the array analysis to be viewed as a spherical waveguide junction discontinuity problem. The apertures, in general, carry dual polarized circular waveguide TE11 modes. Two independent formulations-the unit cell method and the eigenexcitation method that take rotational symmetry into account-are developed and are checked against each other numerically for computational accuracy. These two formulations are analytically linked as discrete Fourier series pairs. It is seen that mutual coupling along the array decays more rapidly when the polarization of excitation is perpendicular to the array plane than when it is parallel to it. This analysis has been applied in the performance analysis of the Dome Lens phased array radar antenna. RP BONDYOPADHYAY, PK (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,ELECTROMAGNET SYST BRANCH,MAIL CODE EE-3,HOUSTON,TX 77058, USA. NR 13 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD AUG PY 1992 VL 40 IS 8 BP 857 EP 866 DI 10.1109/8.163423 PG 10 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JT921 UT WOS:A1992JT92100001 ER PT J AU LEE, TH CLARK, TL BURNSIDE, WD GUPTA, IJ AF LEE, TH CLARK, TL BURNSIDE, WD GUPTA, IJ TI CRITICAL RANGE EVALUATION USING A DIAGONAL FLAT-PLATE SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID REFLECTORS AB A novel technique is presented to image stray signals in RCS measurement ranges. In this technique, the scattered fields of a flat plate in the diagonal plane are measured in a range for various frequencies and look angles. The scattered field data is then processed to generate an inverse synthetic aperture radar (ISAR) image of the diagonal flat plate. It is shown that scattering mechanisms associated with various stray signals can be identified by using the ISAR image. This leads to better understanding of the range and possible chamber improvements. Scattering mechanisms as small as 90 dB below the plate broadside scattered field level have been observed in the image domain due to the high directivity and low sidelobe characteristics associated with the diagonal flat plate backscattered fields. The results obtained from evaluating the two compact range facilities at The Ohio State University ElectroScience Laboratory are presented to illustrate the virtues of this new range evaluation technique. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP LEE, TH (reprint author), OHIO STATE UNIV,DEPT ELECT ENGN,ELECTROSCI LAB,COLUMBUS,OH 43212, USA. NR 10 TC 1 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD AUG PY 1992 VL 40 IS 8 BP 966 EP 974 DI 10.1109/8.163435 PG 9 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JT921 UT WOS:A1992JT92100013 ER PT J AU LING, CC REBEIZ, GM AF LING, CC REBEIZ, GM TI 94 GHZ INTEGRATED HORN MONOPULSE ANTENNAS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note AB A monolithic azimuthal monopulse antenna for 94 GHz applications has been developed. The structure consists of a single dipole suspended in one plane of an integrated horn cavity to obtain the sum pattern, and an antiparallel pair of dipoles suspended in a different plane of the same horn cavity to achieve the difference pattern. Pattern measurements of microwave models and on the millimeter-wave antennas show good agreement with theory and exhibit symmetry with a sharp -30 dB null at broadside for the difference antenna. Microwave model measurements show input impedances close to 50 OMEGA, with greater than -25 dB isolation between sum and difference antennas across a 10% bandwidth. C1 UNIV MICHIGAN,DEPT COMP SCI,ANN ARBOR,MI 48109. RP LING, CC (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN,NASA,CTR SPACE TETRAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 12 TC 15 Z9 15 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD AUG PY 1992 VL 40 IS 8 BP 981 EP 984 DI 10.1109/8.163437 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JT921 UT WOS:A1992JT92100015 ER PT J AU GAIER, JR AF GAIER, JR TI INTERCALATED GRAPHITE FIBER COMPOSITES AS EMI SHIELDS IN AEROSPACE STRUCTURES SO IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY LA English DT Note ID EPOXY COMPOSITES; RESISTIVITY; STABILITY; CHLORIDE; PRISTINE; BROMINE; CARBON AB The requirements for electromagnetic interference (EMI) shielding in aerospace structures are more complicated than those for ground structures because of their weight limitations. As a result, the best EMI shielding materials must combine low density, high strength, and high elastic modulus with high shielding ability. EMI shielding characteristics were calculated for shields formed from pristine and intercalated graphite fiber/epoxy composites and compare to preliminary experimental results for these materials and to the characteristics of shields made from aluminum. Calculations indicate that effective EMI shields could be fabricated from intercalated graphite composites which would have less than 12 percent of the mass of conventional aluminum shields, based on mechanical properties and shielding characteristics alone. RP GAIER, JR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 9 TC 10 Z9 10 U1 1 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9375 J9 IEEE T ELECTROMAGN C JI IEEE Trans. Electromagn. Compat. PD AUG PY 1992 VL 34 IS 3 BP 351 EP 356 DI 10.1109/15.155854 PN 2 PG 6 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA KX605 UT WOS:A1992KX60500013 ER PT J AU AUDOIN, C DIENER, WA AF AUDOIN, C DIENER, WA TI FREQUENCY, PHASE, AND AMPLITUDE CHANGES OF THE HYDROGEN MASER OSCILLATION SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article AB The frequency, the phase, and the amplitude changes of the hydrogen maser oscillation, which are induced by the modulation of the cavity resonant frequency, are considered. The results obtained apply specifically to one of the H-maser cavity autotuning methods which is actually implemented, namely the cavity frequency-switching method. The frequency, the phase, and the amplitude changes are analyzed theoretically. The phase and the amplitude variations are measured experimentally. It is shown, in particular, that the phase of oscillation is subjected to abrupt jumps at the times of the cavity frequency switching, whose magnitude is specified. The results given can be used for the design of a phase-locked loop aimed at minimizing the transfer of the phase modulation to the slaved VCXO. C1 JET PROP LAB,PASADENA,CA 91109. RP AUDOIN, C (reprint author), UNIV PARIS 11,HORL ATOM LAB,CNRS,UNITE PROPRE RECH,F-91405 ORSAY,FRANCE. NR 6 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 SN 0018-9456 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD AUG PY 1992 VL 41 IS 4 BP 461 EP 466 DI 10.1109/19.155908 PG 6 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JK594 UT WOS:A1992JK59400001 ER PT J AU WINKERT, G AF WINKERT, G TI 2 CMOS GATE ARRAYS FOR THE EPACT EXPERIMENT SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1991 NUCLEAR SCIENCE SYMP AND MEDICAL IMAGING CONF CY OCT 02-09, 1991 CL SANTA FE, NM SP IEEE AB Two semicustom CMOS digital gate arrays are described which have been developed for the Energetic Particles: Acceleration, Composition, and Transport (EPACT) experiment. The first device, the "Event Counters: 16x24-bit" (EC1624), implements sixteen 24-bit ripple counters and has flexible counting and readout options. The second device, die "Serial Transmitter/Receiver" (SXR), is a multi-personality chip that can be used at either end of a serial, synchronous communications data link. It can be configured as a master in a central control unit, or as one of many slaves within remote assemblies. Together, a network of SXRs allows for commanding and verification of distributed control signals. Both gate arrays are radiation hardened and qualified for space flight use. The architecture of each chip is presented and the benefits to the experiment summarized. RP WINKERT, G (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 6631,GREENBELT,MD 20771, USA. NR 6 TC 1 Z9 1 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 1992 VL 39 IS 4 BP 789 EP 794 DI 10.1109/23.159708 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA JR353 UT WOS:A1992JR35300056 ER PT J AU HUBBARD, GS MCMURRAY, RE KELLER, RG WERCINSKI, PF WALTON, JT VIERINEN, K AF HUBBARD, GS MCMURRAY, RE KELLER, RG WERCINSKI, PF WALTON, JT VIERINEN, K TI RESULTS FROM A SI(LI) GAMMA-RAY DETECTOR STACK FOR FUTURE MARS MISSIONS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1991 NUCLEAR SCIENCE SYMP AND MEDICAL IMAGING CONF CY OCT 02-09, 1991 CL SANTA FE, NM SP IEEE AB We present Monte Carlo analysis and experimental data from a novel lithium-drifted silicon detector stack for gamma ray spectroscopy instrumentation in future Mars surface landers and other planetary missions. The Monte Carlo analysis shows full energy photopeaks even in the range of approximately 100 keV to 2 MeV where, in Si, Compton scattering dominates the absorption processes. Laboratory data is shown for an experimental detector stack of 4 planar Si(Li) devices, each 5 mm thick with an active area 2 cm in diameter. All the experimental data were collected with maximum temperature of the stack at 175 K. Background reduction is achieved by using the detector of the stack closest to the source in anticoincidence. We present a comparison of experimental data from the stack with the Monte Carlo model for CS-137 (662 keV). Agreement is shown to be good, with a full energy photopeak clearly seen (FWHM approximately 10 keV). Experimental stack data is also shown for multiple peaks at 511 keV (Na-22) and 662 keV (CS-137). The peaks are Clearly resolved (FWHM approximately 10 keV), and are compared with the results obtained using a 8% resolution, 3 in. x 3 in. NaI(TI) device (FWHM approximately 50 keV). C1 LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. UNIV HELSINKI,SF-00170 HELSINKI 17,FINLAND. RP HUBBARD, GS (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 15 TC 3 Z9 3 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 1992 VL 39 IS 4 BP 981 EP 986 DI 10.1109/23.159745 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA JR353 UT WOS:A1992JR35300093 ER PT J AU NOLAN, PL BERTSCH, DL FICHTEL, CE HARTMAN, RC HOFSTADTER, R HUGHES, EB HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C PINKAU, K ROTHERMEL, H SCHNEID, E SOMMER, M SREEKUMAR, P THOMPSON, DJ AF NOLAN, PL BERTSCH, DL FICHTEL, CE HARTMAN, RC HOFSTADTER, R HUGHES, EB HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C PINKAU, K ROTHERMEL, H SCHNEID, E SOMMER, M SREEKUMAR, P THOMPSON, DJ TI PERFORMANCE OF THE EGRET ASTRONOMICAL GAMMA-RAY TELESCOPE SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1991 NUCLEAR SCIENCE SYMP AND MEDICAL IMAGING CONF CY OCT 02-09, 1991 CL SANTA FE, NM SP IEEE ID CALIBRATION AB On April 5, 1991, the Space Shuttle Atlantis carried the Compton Gamma Ray Observatory (CGRO) into orbit, deploying the satellite on April 7. The EGRET instrument was activated on April 15, and the first month of operations was devoted to verification of the instrument performance. Measurements made during that month and in the subsequent sky survey phase have verified that the instrument time resolution, angular resolution, and gamma ray detection efficiency are all within nominal limits. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERRESTR PHYS,GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP NOLAN, PL (reprint author), STANFORD UNIV,STANFORD,CA 94305, USA. RI Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; Nolan, Patrick/A-5582-2009 OI Thompson, David/0000-0001-5217-9135; NR 6 TC 34 Z9 34 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 1992 VL 39 IS 4 BP 993 EP 996 DI 10.1109/23.159747 PG 4 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA JR353 UT WOS:A1992JR35300095 ER PT J AU LUTZ, RR WONG, JSK AF LUTZ, RR WONG, JSK TI DETECTING UNSAFE ERROR RECOVERY SCHEDULES SO IEEE TRANSACTIONS ON SOFTWARE ENGINEERING LA English DT Article DE ASYNCHRONOUS SYSTEMS; CONSISTENCY CONSTRAINTS; ERROR RECOVERY; FAULT TOLERANCE; HARD-REAL-TIME SYSTEMS; MODELING; PRECEDENCE; SAFETY; SCHEDULING; TIMING CONSTRAINTS ID REAL-TIME SYSTEMS; SAFETY ANALYSIS; TEMPORAL LOGIC AB This paper presents a mechanism for modeling timing, precedence, and data-consistency constraints on concurrently executing processes. The model allows durations and intervals between events to be specified. An algorithm is provided to detect schedules which may be unsafe with respect to the constraints. This work, motivated by the design and validation of autonomous error-recovery strategies on the Galileo spacecraft, appears to be applicable to a variety of asynchronous real-time systems. C1 JET PROP LAB,PASADENA,CA 91109. RP LUTZ, RR (reprint author), IOWA STATE UNIV SCI & TECHNOL,DEPT COMP SCI,AMES,IA 50011, USA. NR 41 TC 4 Z9 4 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0098-5589 J9 IEEE T SOFTWARE ENG JI IEEE Trans. Softw. Eng. PD AUG PY 1992 VL 18 IS 8 BP 749 EP 760 DI 10.1109/32.153384 PG 12 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA JJ867 UT WOS:A1992JJ86700007 ER PT J AU KIM, HH AF KIM, HH TI URBAN HEAT-ISLAND SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SEMI-ARID REGIONS; THERMAL IR DATA; SURFACE-TEMPERATURE; ENERGY-BALANCE; EVAPOTRANSPIRATION; MOISTURE; RADIATION; DROUGHT; CLIMATE; ALBEDOS AB The phenomenon of an urban heat island was investigated by the use of Landsat/Thematic Mapper data sets collected over the metropolitan area of Washington, DC. By combining the derived spectral albedos and temperatures, surface energy composites of five surface categories were analysed. The results indicate that urban heating is attributable to a large excess in heat from the rapidly heating urban surfaces consisting of buildings, asphalt, bare-soil and short grasses. In summer, the symptoms of diurnal heating begin to appear by mid-morning and can be about 10-degrees-C warmer than nearby woodlands. RP KIM, HH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 34 TC 90 Z9 99 U1 5 U2 42 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD AUG PY 1992 VL 13 IS 12 BP 2319 EP 2336 PG 18 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA JM441 UT WOS:A1992JM44100012 ER PT J AU KREUTZDELGADO, K JAIN, A RODRIGUEZ, G AF KREUTZDELGADO, K JAIN, A RODRIGUEZ, G TI RECURSIVE FORMULATION OF OPERATIONAL SPACE CONTROL SO INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH LA English DT Article ID MANIPULATORS AB A recently developed spatial operator algebra approach to modeling and analysis of multibody robotic systems is used to develop O(n) recursive algorithms that compute the operational space mass matrix and the operational space coriolis/centrifugal and gravity terms of an n-link serial manipulator These algorithms enable an O(n) recursive implementation of operational space control. C1 JET PROP LAB,PASADENA,CA 91109. RP KREUTZDELGADO, K (reprint author), UNIV CALIF SAN DIEGO,DEPT ELECT & COMP ENGN,LA JOLLA,CA 92093, USA. NR 18 TC 20 Z9 20 U1 0 U2 1 PU MIT PRESS PI CAMBRIDGE PA 55 HAYWARD ST JOURNALS DEPT, CAMBRIDGE, MA 02142 SN 0278-3649 J9 INT J ROBOT RES JI Int. J. Robot. Res. PD AUG PY 1992 VL 11 IS 4 BP 320 EP 328 DI 10.1177/027836499201100405 PG 9 WC Robotics SC Robotics GA JH935 UT WOS:A1992JH93500005 ER PT J AU FRITSCH, JM CHARLES, JB BENNETT, BS JONES, MM ECKBERG, DL AF FRITSCH, JM CHARLES, JB BENNETT, BS JONES, MM ECKBERG, DL TI SHORT-DURATION SPACEFLIGHT IMPAIRS HUMAN CAROTID BARORECEPTOR-CARDIAC REFLEX RESPONSES SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE MICROGRAVITY; ORTHOSTATIC; VAGAL ID ORTHOSTATIC HYPOTENSION; BAROREFLEX RESPONSES; PRESSURE; WEIGHTLESSNESS; HYPERTENSION; FITNESS; SYSTEM AB Orthostatic intolerance is a predictable but poorly understood consequence of space travel. Because arterial baroreceptors modulate abrupt pressure transients, we tested the hypothesis that spaceflight impairs baroreflex mechanisms. We studied vagally mediated carotid baroreceptor-cardiac reflex responses (provoked by neck pressure changes) in the supine position and heart rate and blood pressure in the supine and standing positions in 16 astronauts before and after 4- to 5-day Space Shuttle missions. On landing day, resting R-R intervals and standard deviations, and the slope, range, and position of operational points on the carotid transmural pressure-sinus node response relation were all reduced relative to preflight. Stand tests on landing day revealed two separate groups (one maintained standing arterial pressure better) that were separated by preflight slopes, operational points, and supine and standing R-R intervals and by preflight-to-postflight changes in standing pressures, body weights, and operational points. Our results suggest that short-duration spaceflight leads to significant reductions in vagal control of the sinus node that may contribute to, but do not account completely for, orthostatic intolerance. C1 VET AFFAIRS MED CTR,HUNTER HOLMES MCGUIRE DEPT,DEPT MED,RICHMOND,VA 23249. VET AFFAIRS MED CTR,HUNTER HOLMES MCGUIRE DEPT,DEPT PHYSIOL,RICHMOND,VA 23249. KRUG LIFE SCI,HOUSTON,TX 77058. RP FRITSCH, JM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,CODE SD5,HOUSTON,TX 77058, USA. NR 40 TC 160 Z9 173 U1 0 U2 3 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 BP 664 EP 671 PG 8 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JK675 UT WOS:A1992JK67500043 PM 1399995 ER PT J AU ARNAUD, SB FUNG, P POPOVA, IA MOREYHOLTON, ER GRINDELAND, RE AF ARNAUD, SB FUNG, P POPOVA, IA MOREYHOLTON, ER GRINDELAND, RE TI CIRCULATING PARATHYROID-HORMONE AND CALCITONIN IN RATS AFTER SPACEFLIGHT SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE CALCIUM-REGULATING HORMONES; MICROGRAVITY; TAIL SUSPENSION ID CALCIUM; HYPERPARATHYROIDISM; RESTRICTION; MODULATION; AGE AB Parathyroid hormone and calcitonin, two major calcium-regulating hormones, were measured in the plasma of five experimental groups of rats to evaluate postflight calcium homeostasis after the 14-day COSMOS 2044 flight. Parathyroid hormone values were slightly higher in the flight animals (F) than in the appropriate cage and diet controls (S) (44 +/- 21 vs. 21 +/- 4 pg/ml, P < 0.05), but they were the same as in the vivarium controls (V), which had different housing and feeding schedules. Neither V nor S showed the increase in plasma creatinine phosphorus and magnesium found in F, features of early renal insufficiency. F showed the lowest mean plasma calcitonin that was statistically different from V only. This difference in F and V (22 +/- 11 vs. 49 +/- 16 pg/ml, P < 0.05) was most likely due to failure of circulating calcitonin in F to show the normal age-dependent increase we demonstrated in age-matched controls in a separate experiment. Basal values for parathyroid hormone and calcitonin were unchanged after 2 wk of hindlimb suspension, a flight simulation model, in age-matched and younger rats. From a time course experiment serum calcium was higher and parathyroid hormone lower after 4 wk than in ambulatory controls. Postflight circulating levels of parathyroid hormone appear to reflect disturbances in calcium homeostasis from impaired renal function of undetermined cause, whereas levels of calcitonin reflect depression of a normal growth process. C1 MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. RP ARNAUD, SB (reprint author), NASA,AMES RES CTR,DIV LIFE SCI SL-239-11,MOFFETT FIELD,CA 94035, USA. NR 24 TC 10 Z9 10 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S169 EP S173 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400027 PM 1526947 ER PT J AU DOTY, SB MOREYHOLTON, ER DURNOVA, GN KAPLANSKY, AS AF DOTY, SB MOREYHOLTON, ER DURNOVA, GN KAPLANSKY, AS TI MORPHOLOGICAL-STUDIES OF BONE AND TENDON SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE BONE FORMATION; SPACEFLIGHT; ELECTRON MICROSCOPY; HISTOCHEMISTRY; BONE VASCULATURE; COLLAGEN ORGANIZATION; TENDON ID TRABECULAR BONE; SPACEFLIGHT; COLLAGEN; RATS AB The Soviet biosatellite COSMOS 2044 carried adult rats on a space-flight that lasted 13.8 days and was intended to repeat animal studies carried out on COSMOS 1887. Skeletal tissue and tendon from animals flown on COSMOS 2044 were studied by light and electron microscopy, histochemistry, and morphometric techniques. Studies were confined to the bone cells and vasculature from the weight-bearing tibias. Results indicated that vascular changes at the periosteal and subperiosteal region of the tibia were not apparent by light microscopy or histochemistry. However, electron microscopy indicated that vascular inclusions were present in bone samples from the flight animals. A unique combination of microscopy and histochemical techniques indicated that the endosteal osteoblasts from this same middiaphyseal region demonstrated a slight (but not statistically significant) reduction in bone cell activity. Electron-microscopic studies of the tendons from metatarsal bones showed a collagen fibril disorganization as a result of spaceflight. Thus changes described for COSMOS 1887 were present in COSMOS 2044, but the changes ascribed to spaceflight were not as evident. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. RP DOTY, SB (reprint author), HOSP SPECIAL SURG,ELECTRON MICROSCOPY LAB,RM 424,RES BLDG,535 E 70TH ST,NEW YORK,NY 10021, USA. NR 14 TC 18 Z9 19 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S10 EP S13 PG 4 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400003 PM 1526935 ER PT J AU GARETTO, LP MOREY, ER DURNOVA, GN KAPLANSKY, AS ROBERTS, WE AF GARETTO, LP MOREY, ER DURNOVA, GN KAPLANSKY, AS ROBERTS, WE TI PREOSTEOBLAST PRODUCTION IN COSMOS 2044 RATS - SHORT-TERM RECOVERY OF OSTEOGENIC POTENTIAL SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE BONE; OSTEOGENESIS; CELL DIFFERENTIATION; SPACEFLIGHT; RECOVERY; MICROGRAVITY ID PERIODONTAL-LIGAMENT; OSTEOBLAST HISTOGENESIS; TRABECULAR BONE; SPACEFLIGHT; DIFFERENTIATION; WEIGHTLESSNESS; PROLIFERATION; METABOLISM; SKELETON; BEARING AB The influence of a 13.8-day spaceflight and approximately 8.5-11 h of recovery at 1 g on fibroblast-like osteoblast precursor cells was assessed in the periodontal ligament of rat maxillary first molars. Preosteoblasts (C + D cells), less differentiated progenitor cells (A + A' cells), and nonosteogenic fibroblast-like cells (B cells) were identified by nuclear volume analysis (i.e., A + A' = 40-79-mu-m3; B = 80-119-mu-m3; C + D greater-than-or-equal-to 120-mu-m3). No differences were observed among flight (F), synchronous (SC), vivarium, and basal control groups in the A + A' (F: 28.0 +/- 3.7 vs. SC: 27.4 +/- 2.2), B (F: 33.1 +/- 1.4 vs. SC: 32.4 +/- 2.4), or C + D (F: 38.4 +/- 4.5 vs. SC: 39.2 +/- 1.6) cell compartments (means +/- SE, n = 5). Compared with previous spaceflight experiments, the present data are consistent with a postflight response to replenish preosteoblasts and restore periodontal ligament osteogenic potential. These data emphasize the need to 1) unequivocally determine the flight effect by killing the animals in-flight and 2) further assess the postflight recovery phenomenon. C1 INDIANA UNIV,SCH MED,DEPT PHYSIOL BIOPHYS,INDIANAPOLIS,IN 46202. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. RP GARETTO, LP (reprint author), INDIANA UNIV,SCH DENT,DEPT ORTHODONT,BONE RES LAB,1121 W MICHIGAN ST,INDIANAPOLIS,IN 46202, USA. FU NIDCR NIH HHS [DE 09237-01] NR 24 TC 6 Z9 8 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S14 EP S18 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400004 PM 1526941 ER PT J AU GRINDELAND, RE BALLARD, RW CONNOLLY, JP VASQUES, MF AF GRINDELAND, RE BALLARD, RW CONNOLLY, JP VASQUES, MF TI OVERVIEW SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article ID SPACE RP GRINDELAND, RE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 12 TC 38 Z9 40 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S1 EP S3 PG 3 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400001 PM 1526934 ER PT J AU HYMER, WC GRINDELAND, R KRASNOV, I VICTOROV, I MOTTER, K MUKHERJEE, P SHELLENBERGER, K VASQUES, M AF HYMER, WC GRINDELAND, R KRASNOV, I VICTOROV, I MOTTER, K MUKHERJEE, P SHELLENBERGER, K VASQUES, M TI EFFECTS OF SPACEFLIGHT ON RAT PITUITARY CELL-FUNCTION SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE GROWTH HORMONE; PROLACTIN; MICROGRAVITY ID GROWTH-HORMONE; ANTERIOR-PITUITARY; STRESS PROTEINS; PROLACTIN; INVITRO; SERUM AB The secretory capacity of growth hormone (GH) and prolactin (PRL) cells prepared from rats flown in space on the 12.5-day mission of COSMOS 1887 and the 14-day mission of COSMOS 2044 was evaluated in several postflight tests on Earth. The results showed statistically significant and repeatable decrements in hormone release, especially when biologic (rather than immunologic) assays were used in the tests. Significant and repeatable intracellular changes in GH cells from the flight animals were also found; most important were increases in the GH-specific cytoplasmic staining intensities and cytoplasmic areas occupied by hormone. Tail suspension of rats for 14 days, an established model for mimicking musculoskeletal changes in rats flown in space, resulted in some changes in GH and PRL cell function that were similar to those from animals flown in space. Our results add to a growing body of data that describe deconditioning of physiological systems in spaceflight and provide insights into the time frame that might be required for readaptation of the GH/PRL cell system on return to Earth. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MINIST PUBL HLTH USSR,BRAIN RES INST,MOSCOW,USSR. MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. RP HYMER, WC (reprint author), PENN STATE UNIV,DEPT MOLEC & CELL BIOL,6 ALTHOUSE LAB,UNIV PK,PA 16802, USA. RI Victorov, Ilya/C-4680-2012 NR 28 TC 32 Z9 32 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S151 EP S157 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400024 PM 1526944 ER PT J AU KEIL, L EVANS, J GRINDELAND, R KRASNOV, I AF KEIL, L EVANS, J GRINDELAND, R KRASNOV, I TI PITUITARY OXYTOCIN AND VASOPRESSIN CONTENT OF RATS FLOWN ON COSMOS 2044 SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE SPACEFLIGHT; NEUROHYPOPHYSIS; STRESS; NEUROSECRETION; MICROGRAVITY ID PLASMA VASOPRESSIN; SECRETION; STRESS; CHOLECYSTOKININ AB Preliminary studies in rats (COSMOS 1887) suggested that levels of posterior pituitary hormones were reduced by exposure to spaceflight. To confirm these preliminary findings, we obtained pituitary tissue from rats flown for 14 days on COSMOS 2044. Posterior pituitary content of oxytocin (OT) and vasopressin (VP) were measured in these tissues as well as those from ground-based controls. The synchronous control group had feeding and lighting schedules synchronized to those in the spacecraft and were maintained in flight-type cages. Another group was housed in vivarium cages; a third group was tail suspended (T), a method used to simulate microgravity. Flight rats showed an average reduction of 27% (P < 0.05) in pituitary OT and VP compared with the three control groups. When hormone content was expressed in terms of pituitary protein (mu-g hormone/mg protein), the average decrease in OT and VP for the flight animals ranged from 20 to 33% (P < 0.05) compared with the various control groups. Reduced levels of pituitary OT and VP were similar to preliminary measurements from the COSMOS 1887 mission and appear to result from exposure to spaceflight. These data suggest that changes in the rate of hormone secretion or synthesis may have occurred during exposure to microgravity. C1 MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. RP KEIL, L (reprint author), NASA,AMES RES CTR,MAIL STOP 239-11,MOFFETT FIELD,CA 94035, USA. NR 15 TC 8 Z9 8 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S166 EP S168 PG 3 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400026 PM 1526946 ER PT J AU MEDNIEKS, MI POPOVA, I GRINDELAND, RE AF MEDNIEKS, MI POPOVA, I GRINDELAND, RE TI PHOTOAFFINITY-LABELING OF REGULATORY SUBUNITS OF PROTEIN KINASE-A IN CARDIAC CELL-FRACTIONS OF RATS SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE ADENOSINE 3',5'-CYCLIC MONOPHOSPHATE ID CYCLIC-AMP; MECHANISMS; MUSCLE; DESENSITIZATION; ULTRASTRUCTURE; MYOCARDIUM; RECEPTORS; HORMONES; GRAVITY AB The regulatory (R) subunits of adenosine 3',5',-cyclic monophosphate-dependent protein kinase were measured by photoaffinity labeling in heart tissue of rats flown on COSMOS 2044. Densitometric analyses showed a significant decrease of RII subunits in the particulate cell fraction extract (S2; P < 0.05 in all cases) when extracts of tissue samples from vivarium controls were compared with those from flight animals. Photoaffinity labeling of the soluble fraction (S1) was unaffected by spaceflight or any of the simulation conditions. This was previously observed in heart muscle of rats flown on Spacelab 3 and COSMOS 1887 missions. A change in either the number or reactivity of the R subunits apparently results from some aspect of spaceflight. Proteins of the S2 fraction constitute a minor (<10%) component of the total, whereas the S1 fraction contained most of the cell proteins. No changes were seen when total incorporation of photoaffinity label was calculated on the basis of adrenal gland weights. A negative correlation resulted on comparison of controls with flight, synchronous control, and a tail-suspended simulation group of animals when incorporation of total counts due to azido labeling was based on body weights. Environmental factors that influence organismic responses may alter individual hormonal responses and may be reflected on the molecular level of organization. Conversely, changes in a relatively minor aspect of adenosine 3',5'-cyclic monophosphate-mediated reactions may be representative of a metabolic effect on an organismic level. C1 MINIST PUBL HLTH USSR, INST BIOMED PROBLEMS, MOSCOW, USSR. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP UNIV ILLINOIS, COLL DENT, DEPT PEDIAT, PEDIAT ENDOCRINOL SECT, 801 S PAULINA AVE, CHICAGO, IL 60612 USA. NR 32 TC 1 Z9 1 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 EI 1522-1601 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S101 EP S106 PG 6 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400016 PM 1526936 ER PT J AU MERRILL, AH WANG, E MULLINS, RE GRINDELAND, RE POPOVA, IA AF MERRILL, AH WANG, E MULLINS, RE GRINDELAND, RE POPOVA, IA TI ANALYSES OF PLASMA FOR METABOLIC AND HORMONAL CHANGES IN RATS FLOWN ABOARD COSMOS-2044 SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE SPACEFLIGHT; MICROGRAVITY; PLASMA ENZYMES; ELECTROLYTES; HORMONES ID COSMOS-1887; SPACEFLIGHT AB Plasma samples from rats flown aboard COSMOS 2044 were analyzed for the levels of key metabolites, electrolytes, enzymes, and hormones. The major differences between the flight group and the synchronous control were elevations in glucose, cholesterol, phosphate, creatinine, blood urea nitrogen, lactate dehydrogenase, and aspartate aminotransferase and decreased levels of thyroxine. Most of these differences were not mimicked by tail suspension of ground-based rats; however, both flight and suspended rats exhibited inhibited testosterone secretion. Corticosterone, immunoreactive growth hormone, and prolactin showed inconsistent differences from the various control groups, suggesting that the levels of these hormones were not due to actual or simulated microgravity. C1 EMORY UNIV,SCH MED,DEPT PATHOL,ATLANTA,GA 30322. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. RP MERRILL, AH (reprint author), EMORY UNIV,SCH MED,ROLLINS RES CTR,DEPT BIOCHEM,ATLANTA,GA 30322, USA. NR 22 TC 28 Z9 28 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S132 EP S135 PG 4 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400020 PM 1526939 ER PT J AU RYKOVA, MP SONNENFELD, G LESNYAK, AT TAYLOR, GR MESHKOV, DO MANDEL, AD MEDVEDEV, AE BERRY, WD FUCHS, BB KONSTANTINOVA, IV AF RYKOVA, MP SONNENFELD, G LESNYAK, AT TAYLOR, GR MESHKOV, DO MANDEL, AD MEDVEDEV, AE BERRY, WD FUCHS, BB KONSTANTINOVA, IV TI EFFECT OF SPACEFLIGHT ON NATURAL-KILLER-CELL ACTIVITY SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE MICROGRAVITY ID EXPERIMENT PROGRAM INTERFERON; SPACE-FLIGHT; SHUTTLE; MOUSE; RATS AB The effects of spaceflight on immune cell function were determined in rats flown on COSMOS 2044. Control groups included vivarium, synchronous, and antiortho-statically statically suspended rats. The ability of natural killer cells to lyse two different target cell lines was determined. Spleen and bone marrow cells obtained from flight rats showed significantly inhibited cytotoxicity for YAC-1 target cells compared with cells from synchronous control rats. This could have been due to exposure of the rats to microgravity. Antiorthostatic suspension did not affect the level of cytotoxicity from spleen cells of suspended rats for YAC-1 cells. On the other hand, cells from rats flown in space showed no significant differences from vivarium and synchronous control rats in cytotoxicity for K-562 target cells. Binding of natural killer cells to K-562 target cells was unaffected by spaceflight. Antiorthostatic suspension resulted in higher levels of cytotoxicity from spleen cells for Cr-51-labeled K-562 cells. The results indicate differential effects of spaceflight on function of natural killer cells. This shows that spaceflight has selective effects on the immune response. C1 UNIV LOUISVILLE,SCH MED,DEPT MICROBIOL & IMMUNOL,LOUISVILLE,KY 40292. ACAD MED SCI,INST BIOMED PROBLEMS,MOSCOW 123007,USSR. ACAD MED SCI,INST HUMAN MORPHOL,MOSCOW 117418,USSR. UNIV LOUISVILLE,SCH DENT,DEPT ORAL HLTH,LOUISVILLE,KY 40292. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 23 TC 24 Z9 25 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S196 EP S200 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400031 PM 1526952 ER PT J AU SAWCHENKO, PE ARIAS, C KRASNOV, I GRINDELAND, RE VALE, W AF SAWCHENKO, PE ARIAS, C KRASNOV, I GRINDELAND, RE VALE, W TI EFFECTS OF SPACEFLIGHT ON HYPOTHALAMIC PEPTIDE SYSTEMS CONTROLLING PITUITARY GROWTH-HORMONE DYNAMICS SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE ARCUATE NUCLEUS; GROWTH HORMONE-RELEASING FACTOR; HYPOTHALAMUS; NEUROSECRETORY NEURONS; SOMATOSTATIN; WEIGHTLESSNESS ID CORTICOTROPIN-RELEASING FACTOR; CENTRAL NERVOUS-SYSTEM; MEDIAN-EMINENCE; INSITU HYBRIDIZATION; MESSENGER-RNA; RAT-BRAIN; SOMATOSTATIN; NEURONS; IMMUNOREACTIVITY; PROSOMATOSTATIN AB Immunohistochemical and in situ hybridization localization of peptides derived from, and mRNAs encoding, prepro-somatostatin (ppSS) and prepro-growth hormone-releasing factor (ppGRF) was carried out on hypothalami from rats flown on biosatellites COSMOS 1887 and 2044 to investigate possible effects of reduced gravity on central hypophysiotropic systems controlling growth hormone (GH) secretion. Results from the COSMOS 1887 mission indicated that both SS and GRF immunostaining in the median eminence were diminished in flight animals relative to controls; no differences between groups in staining for other peptidergic neurosecretory systems were apparent. Animals flown on COSMOS 2044 displayed a more pronounced depletion of GRF than SS immunoreactivity from neurosecretory terminals in the median eminence. In addition, flight animals displayed significant 46-50% reductions in the number and signal intensity of presumed hypophysiotropic cells in the arcuate nucleus expressing ppGRF mRNA; positively hybridized cells in the region surrounding the ventromedial nucleus were less markedly affected. Both indexes of ppSS mRNA levels in the anterior periventricular nucleus were similar in flight and control rats. An additional group of animals that experienced hindlimb suspension, a manipulation that mimics the effects of weightlessness on several parameters, did not differ from controls in any of the above measures. These data suggest that exposure to microgravity results in a preferential reduction in GRF peptide and mRNA levels in hypophysiotropic neurons, which may contribute to impaired GH secretion described previously in animals subjected to spaceflight. Effects of weightlessness are not mimicked by hindlimb suspension in this system. C1 CLAYTON FDN RES,CALIF DIV,LA JOLLA,CA 92037. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. RP SAWCHENKO, PE (reprint author), SALK INST,POB 85800,SAN DIEGO,CA 92186, USA. FU NIDDK NIH HHS [DK-26741] NR 31 TC 14 Z9 16 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S158 EP S165 PG 8 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400025 PM 1526945 ER PT J AU SONNENFELD, G MANDEL, AD KONSTANTINOVA, IV BERRY, WD TAYLOR, GR LESNYAK, AT FUCHS, BB RAKHMILEVICH, AL AF SONNENFELD, G MANDEL, AD KONSTANTINOVA, IV BERRY, WD TAYLOR, GR LESNYAK, AT FUCHS, BB RAKHMILEVICH, AL TI SPACEFLIGHT ALTERS IMMUNE CELL-FUNCTION AND DISTRIBUTION SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE MICROGRAVITY; GRANULOCYTE MONOCYTE COLONY-STIMULATING FACTOR; LEUKOCYTE PHENOTYPES ID EXPERIMENT PROGRAM INTERFERON; SPACE-FLIGHT; SHUTTLE; RATS AB Experiments were carried out aboard COSMOS 2044 to determine the effects of spaceflight on immunologically important cell function and distribution. Control groups included vivarium, synchronous, and antiorthostatically suspended rats. In one experiment, rat bone marrow cells were examined in Moscow, for their response to recombinant murine granulocyte/monocyte colony-stimulating factor (GM-CSF). In another experiment, rat spleen and bone marrow cells were stained in Moscow with a variety of antibodies directed against cell surface antigenic markers. These cells were preserved and shipped to the United States for analysis on a flow cytometer. Bone marrow cells from flown and suspended rats showed a decreased response to granulocyte/monocyte colony-stimulating factor compared with bone marrow cells from control rats. Of the spleen cell subpopulations examined from flown rats, only those cells expressing markers for suppressor-cytotoxic T- and helper T-cells showed an increased percentage of stained cells. Bone marrow cells showed an increase in the percentage of cells expressing markers for helper T-cells in the myelogenous population and increased percentages of anti-asialo granulocyte/monocyte-1-bearing interleukin-2 receptor-bearing pan T- and helper T-cells in the lymphocytic population. Cell populations from rats suspended antiorthostatically did not follow the same pattern of distribution of leukocytes as cell populations for flown rats. The results from COSMOS 2044 are similar, but not identical, to earlier results from COSMOS 1887 and confirm that spaceflight can have profound effects on immune system components and activities. C1 UNIV LOUISVILLE,SCH DENT,DEPT ORAL HLTH,LOUISVILLE,KY 40292. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. ACAD MED SCI,INST BIOMED PROBLEMS,MOSCOW 123007,USSR. ACAD MED SCI,INST HUMAN MORPHOL,MOSCOW 117418,USSR. RP SONNENFELD, G (reprint author), UNIV LOUISVILLE,SCH MED,DEPT MICROBIOL,LOUISVILLE,KY 40292, USA. NR 22 TC 46 Z9 48 U1 2 U2 4 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S191 EP S195 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400030 PM 1526951 ER PT J AU VAILAS, AC VANDERBY, R MARTINEZ, DA ASHMAN, RB ULM, MJ GRINDELAND, RE DURNOVA, GN KAPLANSKY, A AF VAILAS, AC VANDERBY, R MARTINEZ, DA ASHMAN, RB ULM, MJ GRINDELAND, RE DURNOVA, GN KAPLANSKY, A TI ADAPTATIONS OF YOUNG-ADULT RAT CORTICAL BONE TO 14 DAYS OF SPACEFLIGHT SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE MATURATION; COLLAGEN; CROSS-LINKS; MINERAL ID PERFORMANCE LIQUID-CHROMATOGRAPHY; ELASTIC PROPERTIES; SPACELAB-3; MATURATION; COLLAGEN; MISSION; MATRIX; GROWTH AB To determine whether mature humeral cortical bone would be modified significantly by an acute exposure to weightlessness, adult rats (110 days old) were subjected to 14 days of microgravity on the COSMOS 2044 biosatellite. There were no significant changes in peak force, stiffness, energy to failure, and displacement at failure in the flight rats compared with ground-based controls. Concentrations and contents of hydroxyproline, calcium, and mature stable hydroxylysylpyridinoline and lysylpyridinoline collagen cross-links remained unchanged after spaceflight. Bone lengths, cortical and endosteal areas, and regional thicknesses showed no significant differences between flight animals and ground controls. Our findings suggest that responsiveness of cortical bone to microgravity is less pronounced in adult rats than in previous spaceflight experiments in which young growing animals were used. We hypothesize that 14 days of spaceflight may not be sufficient to impact the biochemical and biomechanical properties of cortical bone in the mature rat skeleton. C1 UNIV WISCONSIN,DIV ORTHOPED,MADISON,WI 53792. NASA,AMES RES CTR,SPACE PHYSIOL BRANCH,MOFFETT FIELD,CA 94035. TEXAS SCOTTISH RITE HOSP CRIPPLED CHILDREN,DEPT BIOENGN,DALLAS,TX 75219. MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. RP VAILAS, AC (reprint author), UNIV WISCONSIN,BIODYNAM LAB,2000 OBSERV DR GYM UNIT 11,MADISON,WI 53792, USA. RI Martinez, Daniel/A-5825-2008 NR 27 TC 35 Z9 36 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD AUG PY 1992 VL 73 IS 2 SU S BP S4 EP S9 PG 6 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JL194 UT WOS:A1992JL19400002 PM 1526954 ER PT J AU MENEGHINI, R KOZU, T KUMAGAI, H BONCYK, WC AF MENEGHINI, R KOZU, T KUMAGAI, H BONCYK, WC TI A STUDY OF RAIN ESTIMATION METHODS FROM SPACE USING DUAL-WAVELENGTH RADAR MEASUREMENTS AT NEAR-NADIR INCIDENCE OVER OCEAN SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB A question arising from the recent interest in spaceborne weather radar is what methods can be used to estimate precipitation parameters from space. In this paper, dual-wavelength airborne radar data obtained from flights conducted during 1988 and 1989 are used to compare rain rates derived from backscattering and attenuation methods. We begin with a survey of path-averaged rain rates estimated from six methods over four flights. The fairly large number of high rain-rate cases encountered during these experiments allows for the first tests of the surface-reference method applied to the tow-frequency ( 10-GHz) data. To help interpret the results the surface reference methods are studied by means of scatterplots of the surface cross sections at the two frequencies under rain and no-rain conditions. Approximate criteria are given on combining attenuation and backscattering methods to increase the effective dynamic range of the radar. The dual-wavelength capability of the radar is also used to examine the vertical structure of the precipitation: critical to the success of most methods is the ability to distinguish rain from mixed-phase precipitation. Another factor affecting the accuracy of the methods is the drop-size distribution. In the final section of the paper a procedure to estimate the profiled drop-size distribution is applied to the measured radar data. RP MENEGHINI, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 975,GREENBELT,MD 20771, USA. NR 0 TC 66 Z9 67 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD AUG PY 1992 VL 9 IS 4 BP 364 EP 382 DI 10.1175/1520-0426(1992)009<0364:ASOREM>2.0.CO;2 PG 19 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA KE849 UT WOS:A1992KE84900003 ER PT J AU ZANDER, R GUNSON, MR FARMER, CB RINSLAND, CP IRION, FW MAHIEU, E AF ZANDER, R GUNSON, MR FARMER, CB RINSLAND, CP IRION, FW MAHIEU, E TI THE 1985 CHLORINE AND FLUORINE INVENTORIES IN THE STRATOSPHERE BASED ON ATMOS OBSERVATIONS AT 30-DEGREES NORTH LATITUDE SO JOURNAL OF ATMOSPHERIC CHEMISTRY LA English DT Article DE SPECTROSCOPIC OBSERVATIONS; BUDGETS OF CHLORINE AND FLUORINE; HALOGENATED GASES ID MOLECULE SPECTROSCOPY EXPERIMENT; TRACE GASES; CONCENTRATION PROFILES; VERTICAL-DISTRIBUTION; HYDROGEN-FLUORIDE; UPPER TROPOSPHERE; CARBON-DIOXIDE; OZONE; SPACELAB-3; CHLOROFLUOROMETHANES AB The set of high-resolution infrared solar observations made with the Atmospheric Trace Molecule Spectroscopy (ATMOS) - Fourier transform spectrometer from onboard Spacelab 3 (30 April-1 May 1985) has been used to evaluate the total budgets of the odd chlorine and fluorine chemical families in the stratosphere. These budgets are based on volume mixing ratio profiles measured for HCl, HF, CH3Cl, ClONO2, CCl4, CCl2F2, CCl3F, CHClF2, CF4, COF2, and SF6, near 30-degrees north latitude. When including realistic concentrations for species not measured by ATMOS, i.e., the source gases CH3CCl3, and C2F3Cl3 below 25 km, and the reservoirs ClO, HOCl and COFCl between 15 and 40 km (five gases actually measured by other techniques), the 30-degrees-N zonal 1985 mean total mixing ratio of chlorine, Cl, was found to be equal to (2.58 +/- 0.10) ppbv (parts per billion by volume) throughout the stratosphere, with no significant decrease near the stratopause. The results for total fluorine indicate a slight, but steady, decrease of its volume mixing ratio with increasing altitude, around a mean stratospheric value of (1.15 +/- 0.12) ppbv. Both uncertainties correspond to one standard deviation. These mean springtime 1985 stratospheric budgets are commensurate with values reported for the tropospheric Cl and F concentrations in the early 1980s, when allowance is made for the growth rates of their source gases at the ground and the time required for tropospheric air to be transported into the stratosphere. The results are discussed with emphasis on conservation of fluorine and chlorine and the partitioning among source, sink, and reservoir gases throughout the stratosphere. C1 JET PROP LAB, PASADENA, CA 91109 USA. CALTECH, DEPT CHEM ENGN, PASADENA, CA 91125 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. RP STATE UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. NR 53 TC 73 Z9 73 U1 1 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0167-7764 EI 1573-0662 J9 J ATMOS CHEM JI J. Atmos. Chem. PD AUG PY 1992 VL 15 IS 2 BP 171 EP 186 DI 10.1007/BF00053758 PG 16 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA JH309 UT WOS:A1992JH30900006 ER PT J AU ARNAUD, SB NAVIDI, M FUNG, P WOLINSKY, I AF ARNAUD, SB NAVIDI, M FUNG, P WOLINSKY, I TI BONE-MINERAL IN RATS FED HIGH SALT DIETS IN A SPACE-FLIGHT MODEL SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV HOUSTON,HOUSTON,TX 77204. NR 1 TC 2 Z9 2 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1992 VL 7 SU 1 BP S276 EP S276 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA JL595 UT WOS:A1992JL59500731 ER PT J AU LEBLANC, A SCHNEIDER, V SPECTOR, E EVANS, H ROWE, R AF LEBLANC, A SCHNEIDER, V SPECTOR, E EVANS, H ROWE, R TI CALCIUM-ABSORPTION AND ENDOGENOUS SECRETION DURING BED REST SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 BAYLOR COLL MED,HOUSTON,TX 77030. NASA,JOHNSON SPACE CTR,HOUSTON,TX 77030. NR 0 TC 2 Z9 2 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1992 VL 7 SU 1 BP S194 EP S194 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA JL595 UT WOS:A1992JL59500406 ER PT J AU MOREYHOLTON, ER CONE, CM MARTIN, RB AF MOREYHOLTON, ER CONE, CM MARTIN, RB TI CHANGES IN BONE METABOLISM AND BIOMECHANICS AFTER 1, 2, 3, OR 4 WEEKS OF SKELETAL UNLOADING SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF DAVIS,DAVIS,CA 95616. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1992 VL 7 SU 1 BP S324 EP S324 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA JL595 UT WOS:A1992JL59500923 ER PT J AU SCHNEIDER, V OGANOV, V LEBLANC, A RAKHMANOV, A BAKULIN, A GRIGORIEV, A VARONIN, L AF SCHNEIDER, V OGANOV, V LEBLANC, A RAKHMANOV, A BAKULIN, A GRIGORIEV, A VARONIN, L TI SPACE-FLIGHT BONE LOSS AND CHANGE IN FAT AND LEAN BODY-MASS SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. BAYLOR COLL MED,HOUSTON,TX 77030. MOSCOW BIOMED PROBLEMS INST,MOSCOW,USSR. GAGARIN SPACE CTR,MOSCOW,USSR. NR 1 TC 20 Z9 20 U1 0 U2 1 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1992 VL 7 SU 1 BP S122 EP S122 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA JL595 UT WOS:A1992JL59500117 ER PT J AU WHALEN, RT TAMANAHA, T ARNAUD, SB AF WHALEN, RT TAMANAHA, T ARNAUD, SB TI LOADING-DEPENDENT VARIATIONS IN REGIONAL BONE-DENSITY AND LEAN BODY-MASS SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1992 VL 7 SU 1 BP S189 EP S189 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA JL595 UT WOS:A1992JL59500385 ER PT J AU SPENCER, RW CHRISTY, JR AF SPENCER, RW CHRISTY, JR TI PRECISION AND RADIOSONDE VALIDATION OF SATELLITE GRIDPOINT TEMPERATURE ANOMALIES .1. MSU CHANNEL-2 SO JOURNAL OF CLIMATE LA English DT Article AB In Part I of this study, monthly 2.5-degrees gridpoint anomalies in the TIROS-N satellite series Microwave Sounding Unit (MSU) channel 2 brightness temperatures during 1979-88 are evaluated with multiple satellites and radiosonde data for their climate temperature monitoring capability. The MSU anomalies are computed about a 10-year mean annual cycle at each grid point, with the MSUs intercalibrated to a common arbitrary level. The intercalibrations remove relative biases between instruments of up to several tenths of a degree celsius. The monthly gridpoint anomaly agreement between concurrently operating satellites reveals single-satellite precision generally better than 0.07-degrees-C in the tropics and better than 0. 15-degrees-C at higher latitudes. Monthly anomalies in radiosonde channel 2 brightness temperatures computed with the radiative transfer equation compare very closely to the MSU measured anomalies in all climate zones, with correlations generally from 0,94 to 0.98 and standard errors of 0. 15-degrees-C in the tropics to 0.30-degrees-C at high latitudes. Simplification of these radiative transfer calculations to a static weighting profile applied to the radiosonde temperature profile leads to an average degradation of only 0.02-degrees in the monthly skill. In terms of a more traditionally measured quantity, the MSU channel 2 anomalies match best with either the radiosonde 100-20-kPa or 100-15-kPa layer anomalies. No significant spurious trends were found in the 10-yr satellite dataset compared to the radiosondes that would indicate a calibration drift in either system. Thus, sequentially launched, overlapping passive microwave radiometers provide a useful system for monitoring intraseasonal to interannual climate anomalies and offer hope for monitoring of interdecadal trends from space. The Appendix includes previously unpublished details of the MSU gridpoint anomaly dataset construction. Part II of this study addresses the removal from channel 2 of the temperature influence above the 30-kPa level, providing a sharper and thus potentially more useful weighting function for monitoring lower tropospheric temperatures. C1 UNIV ALABAMA,ATMOSPHER SCI PROGRAM,HUNTSVILLE,AL 35899. RP SPENCER, RW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,DIV EARTH SCI & APPLICAT E543,HUNTSVILLE,AL 35812, USA. NR 5 TC 115 Z9 116 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD AUG PY 1992 VL 5 IS 8 BP 847 EP 857 DI 10.1175/1520-0442(1992)005<0847:PARVOS>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KF231 UT WOS:A1992KF23100006 ER PT J AU SPENCER, RW CHRISTY, JR AF SPENCER, RW CHRISTY, JR TI PRECISION AND RADIOSONDE VALIDATION OF SATELLITE GRIDPOINT TEMPERATURE ANOMALIES .2. A TROPOSPHERIC RETRIEVAL AND TRENDS DURING 1979-90 SO JOURNAL OF CLIMATE LA English DT Article AB TIROS-N satellite Microwave Sounding Unit (MSU) channel 2 data from different view angles across the MSU scan swath are combined to remove the influence of the lower stratosphere and much of the upper troposphere on the measured brightness temperatures. The retrieval provides a sharper averaging kernel than the raw channel 2 weighting function. with a peak lowered from 50 kPa to 70 kPa and with only slightly more surface influence than raw channel 2. Monthly 2.5-degrees gridpoint anomalies of this tropospheric retrieval compared between simultaneously operating satellites indicate close agreement, 0.15-degrees-C in the tropics to around 0.30-degrees-C over much of the higher latitudes. The agreement is not as close as with raw channel 2 anomalies because synoptic-scale temperature gradient information across the 2000-km swath of the MSU is lost in the retrieval procedure and because the retrieval involves the magnification of a small difference between two large numbers. Single gridpoint monthly anomaly correlations between the satellite measurements and the radiosonde calculations range from around 0.95 at high latitudes to below 0. 8 i n the tropical west Pacific, with standard errors of estimate of 0.16-degrees-C at Guam to around 0.50-degrees-C at high-latitude continental stations. Calculation of radiosonde temperatures with a static weighting function instead of the radiative transfer equation degrades the standard errors by an average of less than 0.04-degrees-C. Of various standard tropospheric layers, the channel 2 retrieval anomalies correlate best with radiosonde 100-50- or 100-40-kPa-thickness anomalies. A comparison between global and hemispheric anomalies computed for raw channel 2 data versus the, tropospheric retrieval show a correction in the 1979-90 time series for the volcano-induced stratospheric warming of 1982-83, which was independently observed by MSU channel 4. This correction leads to a slightly greater tropospheric warming trend in the 12-year time series (1979-90) for the tropospheric retrieval [0.039-degrees-C (+/-0.03-degrees-C) per decade] than for channel 2 alone [0.022-degrees-C (+/-0.02-degrees-C) per decade]. C1 UNIV ALABAMA,ATMOSPHER SCI PROGRAM,HUNTSVILLE,AL 35899. RP SPENCER, RW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,DIV EARTH SCI & APPLICAT E543,HUNTSVILLE,AL 35812, USA. NR 4 TC 131 Z9 133 U1 1 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD AUG PY 1992 VL 5 IS 8 BP 858 EP 866 DI 10.1175/1520-0442(1992)005<0858:PARVOS>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KF231 UT WOS:A1992KF23100007 ER PT J AU NOEVER, DA AF NOEVER, DA TI STATISTICAL CRYSTALLOGRAPHIC INVESTIGATION OF STABILITY IN MEMBRANE NETWORKS SO JOURNAL OF COLLOID AND INTERFACE SCIENCE LA English DT Article ID FORCES; ARRANGEMENT; EVOLUTION; VESICLES; BILAYERS; CELLS RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-76,HUNTSVILLE,AL 35812, USA. NR 29 TC 0 Z9 0 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9797 J9 J COLLOID INTERF SCI JI J. Colloid Interface Sci. PD AUG PY 1992 VL 152 IS 1 BP 22 EP 32 DI 10.1016/0021-9797(92)90004-6 PG 11 WC Chemistry, Physical SC Chemistry GA JE827 UT WOS:A1992JE82700003 ER PT J AU MILLER, TL LU, HI BUTLER, KA AF MILLER, TL LU, HI BUTLER, KA TI A FULLY NONLINEAR, MIXED SPECTRAL AND FINITE-DIFFERENCE MODEL FOR THERMALLY DRIVEN, ROTATING-FLOWS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID BAROCLINIC ANNULUS WAVES; NUMERICAL SIMULATIONS; TRANSITION C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, HUNTSVILLE, AL 35812 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, NEW TECHNOL INC, HUNTSVILLE, AL 35812 USA. RP NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, DIV EARTH SCI & APPLICAT, HUNTSVILLE, AL 35812 USA. NR 22 TC 5 Z9 5 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 EI 1090-2716 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1992 VL 101 IS 2 BP 265 EP 275 DI 10.1016/0021-9991(92)90004-I PG 11 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JH155 UT WOS:A1992JH15500004 ER PT J AU YU, ST TSAI, YLP SHUEN, JS AF YU, ST TSAI, YLP SHUEN, JS TI 3-DIMENSIONAL CALCULATIONS OF SUPERSONIC REACTING FLOWS USING AN LU-SCHEME SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID IMPLICIT RP YU, ST (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 14 TC 7 Z9 7 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1992 VL 101 IS 2 BP 276 EP 286 DI 10.1016/0021-9991(92)90005-J PG 11 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JH155 UT WOS:A1992JH15500005 ER PT J AU SWANSON, RC TURKEL, E AF SWANSON, RC TURKEL, E TI ON CENTRAL-DIFFERENCE AND UPWIND SCHEMES SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID HYPERBOLIC CONSERVATION-LAWS; HIGH-RESOLUTION SCHEMES; EULER EQUATIONS C1 TEL AVIV UNIV,IL-69978 TEL AVIV,ISRAEL. INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP SWANSON, RC (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. RI Turkel, Eli/F-6297-2011 OI Turkel, Eli/0000-0003-4273-0303 NR 27 TC 192 Z9 202 U1 0 U2 6 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1992 VL 101 IS 2 BP 292 EP 306 DI 10.1016/0021-9991(92)90007-L PG 15 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JH155 UT WOS:A1992JH15500007 ER PT J AU HARIHARAN, SI YU, P SCOTT, JR AF HARIHARAN, SI YU, P SCOTT, JR TI TIME DOMAIN NUMERICAL-CALCULATIONS OF UNSTEADY VORTICAL FLOWS ABOUT A FLAT-PLATE AIRFOIL SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP HARIHARAN, SI (reprint author), UNIV AKRON,DEPT MATH SCI,AKRON,OH 44325, USA. NR 25 TC 8 Z9 8 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1992 VL 101 IS 2 BP 419 EP 430 DI 10.1016/0021-9991(92)90017-S PG 12 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JH155 UT WOS:A1992JH15500017 ER PT J AU PUSEY, ML AF PUSEY, ML TI CONTINUING ADVENTURES IN LYSOZYME CRYSTAL-GROWTH SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 4TH INTERNATIONAL SYMP ON CRYSTAL GROWTH OF BIOLOGICAL MACROMOLECULES - A FEBS ADVANCED LECTURE COURSE 1991 CY AUG 18-24, 1991 CL FRIEBURG, GERMANY ID PROTEIN SOLUBILITIES; KINETICS AB Tetragonal lysozyme solubility decreases with increasing salt concentrations and decreasing temperatures. The interaction of lysozyme with Cl- appears to be more complex than previously thought. An excess of Cl- over the available basic residues was found associated well before the protein saturation concentration was reached. Aggregation was found to involve the replacing of the protein-Cl- with protein-protein interactions. The aggregation process itself has been found to be kinetically, not collisionally controlled. Aggregation occurs at the expense of monomer concentrations. By approximately 3 x supersaturation, monomer concentrations are essentially level, rising only slightly through the concentrations typically used for lysozyme crystal growth. Lysozyme (110) face growth rates were found to be highly dependent upon both the precipitant concentration and temperature. Conditions which lead to lower solubilities in the phase diagram resulted in a shift of the growth rate versus supersaturation ratio curve to the right; i.e., higher supersaturation ratios were required for equivalent (110) face growth rates when either the temperature was decreased or the NaCl concentration increased. Finally, the (110) face growth rate of tetragonal lysozyme was progressively inhibited by continued exposure to solution flow. The rate at which the growth rate was inhibited increased with the solution velocity. RP PUSEY, ML (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,ES76,HUNTSVILLE,AL 35812, USA. NR 42 TC 29 Z9 29 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD AUG PY 1992 VL 122 IS 1-4 BP 1 EP 7 DI 10.1016/0022-0248(92)90219-9 PG 7 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA JP481 UT WOS:A1992JP48100002 ER PT J AU WILSON, LJ PUSEY, ML AF WILSON, LJ PUSEY, ML TI DETERMINATION OF MONOMER CONCENTRATIONS IN CRYSTALLIZING LYSOZYME SOLUTIONS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 4TH INTERNATIONAL SYMP ON CRYSTAL GROWTH OF BIOLOGICAL MACROMOLECULES - A FEBS ADVANCED LECTURE COURSE 1991 CY AUG 18-24, 1991 CL FRIEBURG, GERMANY ID DYNAMIC LIGHT-SCATTERING; PRECRYSTALLIZATION; PROTEINS; GROWTH AB The first step in the crystallization of a protein is aggregation of the individual protein molecules. The detection and characterization of these aggregates is of great interest since the mechanism of nucleation and growth has not been defined. We have developed a non-optical technique for the study of aggregation in lysozyme and other protein solutions. By monitoring the rate at which lysozyme traverses a semipermeable membrane it was possible to quantitate the degree of aggregation in supersaturated solutions. Using this technique, we have measured the concentration of monomers and larger aggregates in under-and oversaturated lysozyme solutions, and in the presence of crystals, at pH 4.0 and 3% NaCl (0.1M NaAc). Comparison of these concentration profiles with (110) face growth rate data supports the theory that tetragonal lysozyme crystals grow by addition of preformed aggregates and not by monomer addition. The data suggest that a considerable population of aggregates larger than dimers are present at lysozyme concentrations above 22 mg/mL. Determination of dimer concentrations, and equilibrium constants for subsequent aggregation levels, are currently underway. RP WILSON, LJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,HUNTSVILLE,AL 35812, USA. NR 22 TC 31 Z9 31 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD AUG PY 1992 VL 122 IS 1-4 BP 8 EP 13 DI 10.1016/0022-0248(92)90220-D PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA JP481 UT WOS:A1992JP48100003 ER PT J AU NOEVER, DA AF NOEVER, DA TI SIZE EFFECTS IN MODELS FOR MECHANICALLY-STRESSED PROTEIN CRYSTALS AND AGGREGATES SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 4TH INTERNATIONAL SYMP ON CRYSTAL GROWTH OF BIOLOGICAL MACROMOLECULES - A FEBS ADVANCED LECTURE COURSE 1991 CY AUG 18-24, 1991 CL FRIEBURG, GERMANY ID GROWTH; MICROGRAVITY AB As protein aggregates increase in size. they become easier to disrupt mechanically. Using the scaling properties of models proposed to govern protein aggregation, the effect of thermal vibrations and gravity are investigated as deforming forces. For typical protein assemblies made of 30 A proteins, the assembled diameter must remain less than 10(2)-10(4) times the molecular radius to survive in finite thermal and gravity fields. The analysis predicts the following experimental outcomes: (1) reductions in gravitational strain should favor larger protein aggregates; (2) in comparing the aggregate stability of different proteins, the addition of peptide chains should stabilize against thermal strain, but should not affect gravitational strain; (3) critical aggregate sizes should show significant (exponential) sensitivity to cluster geometry, solution preparation and growth conditions. The analysis is extended to consider qualitative size effects in crystal damage during X-ray exposure. RP NOEVER, DA (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, ES-76, HUNTSVILLE, AL 35812 USA. NR 22 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD AUG PY 1992 VL 122 IS 1-4 BP 120 EP 135 DI 10.1016/0022-0248(92)90235-B PG 16 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA JP481 UT WOS:A1992JP48100018 ER PT J AU CACIOPPO, E PUSEY, ML AF CACIOPPO, E PUSEY, ML TI THE EFFECTS OF ACID TREATMENT AND CALCIUM-IONS ON THE SOLUBILITY OF CONCANAVALIN-A SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 4TH INTERNATIONAL SYMP ON CRYSTAL GROWTH OF BIOLOGICAL MACROMOLECULES - A FEBS ADVANCED LECTURE COURSE 1991 CY AUG 18-24, 1991 CL FRIEBURG, GERMANY ID EGG-WHITE LYSOZYME; PROTEIN SOLUBILITIES; PH AB The solubilities for concanavalin A from jack bean meal were determined by the sitting drop and micro-column techniques. Solubilities varied with both the measurement technique and protein preparation procedures. Freshly purified and crystallized concanavalin A showed a normal solubility behavior, except for a slight retrograde region at lower temperatures (less-than-or-equal-to 20-degrees-C) and ammonium sulfate concentrations. A salting in effect was also observed at the lower ammonium sulfate concentrations. Treatment with 1.0M acetic acid followed by recalcification lowered the solubility compared to the freshly purified protein as measured with the micro-column technique. Overall, solubilities determined by the sitting drop technique were much higher than those measured with the micro-column method, even for the same protein material and conditions. Further, the results show that protein solubilities must be determined with regard to both the bound and free concentrations of all cofactors. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,ES76,HUNTSVILLE,AL 35812. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35812. NR 19 TC 11 Z9 11 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD AUG PY 1992 VL 122 IS 1-4 BP 208 EP 212 DI 10.1016/0022-0248(92)90247-G PG 5 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA JP481 UT WOS:A1992JP48100030 ER PT J AU MILLER, TY HE, XM CARTER, DC AF MILLER, TY HE, XM CARTER, DC TI A COMPARISON BETWEEN PROTEIN CRYSTALS GROWN WITH VAPOR DIFFUSION METHODS IN MICROGRAVITY AND PROTEIN CRYSTALS USING A GEL LIQUID LIQUID DIFFUSION GROUND-BASED METHOD SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 4TH INTERNATIONAL SYMP ON CRYSTAL GROWTH OF BIOLOGICAL MACROMOLECULES - A FEBS ADVANCED LECTURE COURSE 1991 CY AUG 18-24, 1991 CL FRIEBURG, GERMANY AB Crystals of human serum albumin have been successfully grown in a variety of gels using crystallization conditions otherwise equivalent to those utilized in the popular hanging-drop vapor-equilibration method. Preliminary comparisons of gel grown crystals with crystals grown by the vapor diffusion method via both ground-based and microgravity methods indicate that crystals superior in size and quality may be grown by limiting solutal convection. Preliminary X-ray diffraction statistics are presented. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,DIV MICROGRAV SCI & APPLICAT,SPACE SCI LAB,HUNTSVILLE,AL 35812. NR 14 TC 31 Z9 32 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD AUG PY 1992 VL 122 IS 1-4 BP 306 EP 309 DI 10.1016/0022-0248(92)90261-G PG 4 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA JP481 UT WOS:A1992JP48100044 ER PT J AU NAUMANN, RJ BAUGHER, C AF NAUMANN, RJ BAUGHER, C TI ANALYTICAL ESTIMATES OF RADIAL SEGREGATION IN BRIDGMAN GROWTH FROM LOW-LEVEL STEADY AND PERIODIC ACCELERATIONS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID CRYSTAL-GROWTH; CONVECTION; MELT AB Estimates of the convective flows driven by horizontal temperature gradients in the vertical Bridgman configuration are made for dilute systems subject to the low level accelerations typical of the residual accelerations experienced by a spacecraft in low Earth orbit. The estimates are made by solving the Navier-Stokes momentum equation in one dimension. The mass transport equation is then solved in two dimensions using a first-order perturbation method. This approach is valid provided the convective velocities are small compared to the growth velocity which generally requires a reduced gravity environment. If this condition is satisfied, there will be no circulating cells, and hence no convective transport along the vertical axis. However, the variations in the vertical velocity with radius will give rise to radial segregation. The approximate analytical model developed here can predict the degree of radial segregation for a variety of material and processing parameters to an accuracy well within a factor of two as compared against numerical computations of the full set of Navier-Stokes equations for steady accelerations. It has the advantage of providing more insight into the complex interplay of the processing parameters and how they affect the solute distribution in the grown crystal. This could be extremely valuable in the design of low-gravity experiments in which the intent is to control radial segregation. Also, the analysis can be extended to consider transient and periodic accelerations, which is difficult and costly to do numerically. Surprisingly, it was found that the relative radial segregation falls as the inverse cube of the frequency for periodic accelerations whose periods are short compared with the characteristic diffusion time. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP NAUMANN, RJ (reprint author), UNIV ALABAMA,RES INST,HUNTSVILLE,AL 35899, USA. NR 13 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD AUG PY 1992 VL 121 IS 4 BP 751 EP 768 DI 10.1016/0022-0248(92)90583-5 PG 18 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA JK560 UT WOS:A1992JK56000023 ER PT J AU NOOR, AK TENEK, LH AF NOOR, AK TENEK, LH TI STEADY-STATE NONLINEAR HEAT-TRANSFER IN MULTILAYERED COMPOSITE PANELS SO JOURNAL OF ENGINEERING MECHANICS-ASCE LA English DT Article ID SHELL ELEMENTS; CONDUCTION; APPROXIMATION AB A two-dimensional computational model is developed for nonlinear heat transfer in multilayered composite panels. The model is based on a first-order thermal lamination theory with a linear through-the-thickness variation of temperature. Both convection and nonlinear conduction modes of heat transfer are considered. A three-field mixed finite element model is used for the spatial discretization, with the fundamental unknowns consisting of temperature parameters, flux resultants, and generalized temperature gradients. The flux resultants and generalized temperature gradients are eliminated on the element level. A computational procedure is presented for generating the thermal response and the sensitivity derivatives with respect to material and lamination parameters. The effectiveness of the foregoing two-dimensional computational model is demonstrated by means of two numerical examples in which the solutions obtained by the model are compared with three-dimensional finite element solutions. RP NOOR, AK (reprint author), TECH UNIV VIRGINIA,NASA LANGLEY RES CTR,CTR COMPUTAT STRUCT,HAMPTON,VA 23665, USA. NR 27 TC 9 Z9 9 U1 1 U2 1 PU ASCE-AMER SOC CIVIL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0733-9399 J9 J ENG MECH-ASCE JI J. Eng. Mech.-ASCE PD AUG PY 1992 VL 118 IS 8 BP 1661 EP 1678 DI 10.1061/(ASCE)0733-9399(1992)118:8(1661) PG 18 WC Engineering, Mechanical SC Engineering GA JE361 UT WOS:A1992JE36100010 ER PT J AU SPEZIALE, CG BERNARD, PS AF SPEZIALE, CG BERNARD, PS TI THE ENERGY DECAY IN SELF-PRESERVING ISOTROPIC TURBULENCE REVISITED SO JOURNAL OF FLUID MECHANICS LA English DT Article ID GRID-GENERATED TURBULENCE AB The assumption of self-preservation permits an analytical determination of the energy decay in isotropic turbulence. Batchelor (1948), who was the first to carry out a detailed study of this problem, based his analysis on the assumption that the Loitsianskii integral is a dynamic invariant - a widely accepted hypothesis that was later discovered to be invalid. Nonetheless, it appears that the self-preserving isotropic decay problem has never been reinvestigated in depth subsequent to this earlier work, In the present paper such as analysis is carried out, yielding a much more complete picture of self-preserving isotropic turbulence. It is proven rigorously that complete self-preserving isotropic turbulence admits two general types of asymptotic solutions: one where the turbulent kinetic energy K approximately t-1 and one where K approximately t(-alpha) with an exponent alpha > 1 that is determined explicitly by the initial conditions. By a fixed-point analysis and numerical integration of the exact one-point equations, it is demonstrated that the K approximately t-1 power law decay is the asymptotically consistent high-Reynolds-number solution; the K approximately t(-alpha) decay law is only achieved in the limit as t --> infinity and the turbulence Reynolds number R(t) vanishes. Arguments are provided which indicate that a t-1 power law decay is the asymptotic state toward which a complete self-preserving isotropic turbulence is driven at high Reynolds numbers in order to resolve an O(R(t)1/2) imbalance between vortex stretching and viscous diffusion. Unlike in previous studies, the asymptotic approach to a complete self-preserving state is investigated which uncovers some surprising results. C1 UNIV MARYLAND, DEPT MECH ENGN, COLL PK, MD 20742 USA. RP NASA, LANGLEY RES CTR, INST COMP APPL SCI & ENGN, HAMPTON, VA 23665 USA. NR 38 TC 82 Z9 84 U1 0 U2 4 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 EI 1469-7645 J9 J FLUID MECH JI J. Fluid Mech. PD AUG PY 1992 VL 241 BP 645 EP 667 DI 10.1017/S0022112092002180 PG 23 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JK831 UT WOS:A1992JK83100027 ER PT J AU JAHNKE, LL STANLOTTER, H KATO, K HOCHSTEIN, LI AF JAHNKE, LL STANLOTTER, H KATO, K HOCHSTEIN, LI TI PRESENCE OF METHYL STEROL AND BACTERIOHOPANEPOLYOL IN AN OUTER-MEMBRANE PREPARATION FROM METHYLOCOCCUS-CAPSULATUS (BATH) SO JOURNAL OF GENERAL MICROBIOLOGY LA English DT Article ID METHANE-UTILIZING BACTERIA; GRAM-NEGATIVE BACTERIA; FATTY-ACID; SALMONELLA-TYPHIMURIUM; ESCHERICHIA-COLI; FINE-STRUCTURE; CELL-ENVELOPE; LIPOPOLYSACCHARIDE; HOPANOIDS; DEHYDROGENASE AB Cytoplasmic/intracytoplasmic and outer membrane preparations of Methylococcus capsulatus (Bath) were isolated by sucrose density gradient centrifugation of a total membrane fraction prepared by disruption using a French pressure cell. The cytoplasmic and/or intracytoplasmic membrane fraction consisted of two distinct bands, Ia and Ib (buoyant densities 1.16 and 1.18 g ml-1, respectively) that together contained 57% of the protein, 68% of the phospholipid, 73% of the ubiquinone and 89% of the CN-sensitive NADH oxidase activity. The only apparent difference between these two cytoplasmic bands was a much higher phospholipid content for Ia. The outer membrane fraction (buoyant density 1.23-1.24 g ml-1) contained 60% of the lipopolysaccharide-associated, beta-hydroxypalmitic acid, 74% of the methylsterol, and 66% of the bacteriohopanepolyol (BHP); phospholipid to methyl sterol or BHP ratios were 6: 1. Methanol dehydrogenase activity and a c-type cytochrome were also present in this outer membrane fraction. Phospholipase A activity was present in both the cytoplasmic membrane and outer membrane fractions. The unique distribution of cyclic triterpenes may reflect a specific role in conferring outer membrane stability in this methanotrophic bacterium. C1 UNIV VIENNA,INST MICROBIOL & GENET,A-1010 VIENNA,AUSTRIA. RP JAHNKE, LL (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 53 TC 33 Z9 33 U1 0 U2 7 PU SOC GENERAL MICROBIOLOGY PI READING PA HARVEST HOUSE 62 LONDON ROAD, READING, BERKS, ENGLAND RG1 5AS SN 0022-1287 J9 J GEN MICROBIOL JI J. Gen. Microbiol. PD AUG PY 1992 VL 138 BP 1759 EP 1766 PN 8 PG 8 WC Microbiology SC Microbiology GA JJ072 UT WOS:A1992JJ07200026 PM 11538386 ER PT J AU MITCHELL, HG GANGULI, SB PALMADESSO, PJ AF MITCHELL, HG GANGULI, SB PALMADESSO, PJ TI DIODE-LIKE RESPONSE OF HIGH-LATITUDE PLASMA IN MAGNETOSPHERE-IONOSPHERE COUPLING IN THE PRESENCE OF FIELD-ALIGNED CURRENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID POLAR WIND; LINE PLASMA; PARALLEL; DISTRIBUTIONS; MODEL AB The dynamic processes in the plasma along high-latitude field lines plays an important role in ionosphere-magnetosphere coupling process. We have created a time-dependent, large-scale simulation of these dynamics parallel to the geomagnetic field lines from the ionosphere well into the magnetosphere. The plasma consists of hot e- and H+ of magnetospheric origin and low-energy e-, H+, and O+ of ionospheric origin. Including multiple electron species, a major improvement to the model, has allowed us for the first time to simulate the upward current region properly and to dynamically simulate the diodelike response of the field-line plasma to the parallel currents coupling the ionosphere and magnetosphere. It is shown that return currents flow with small resistance, while upward currents produce kilovolt-sized potential drops along the field, as concluded from satellite observations. The kilovolt potential drops are due to the effect of the converging magnetic field on the high-energy magnetospheric electrons. C1 SCI APPLICAT INT CORP,DIV PLASMA PHYS,MCLEAN,VA 22102. USN,RES LAB,DIV PLASMA PHYS,WASHINGTON,DC 20375. RP MITCHELL, HG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,GREENBELT,MD 20771, USA. NR 16 TC 17 Z9 17 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1992 VL 97 IS A8 BP 12045 EP 12056 DI 10.1029/92JA00796 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH648 UT WOS:A1992JH64800003 ER PT J AU BARNES, A AF BARNES, A TI THEORY OF MAGNETOHYDRODYNAMIC WAVES - THE WKB APPROXIMATION REVISITED SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; TRANSPORT AB Past treatments of the eikonal or WKB theory of the propagation of magnetohydrodynamic waves have assumed a strictly isentropic background. If in fact there is a gradient in the background entropy, then in second order in the WKB ordering, adiabatic fluctuations (in the Lagrangian sense) are not strictly isentropic in the Eulerian sense. This means that in the second order of the WKB expansion, which determines the variation of wave amplitude along rays, the violation of isentropy must be accounted for. The present paper revisits the derivation of the WKB approximation for small-amplitude magnetohydrodynamic waves, allowing for possible spatial variation of the background entropy. The equation of variation of wave amplitude is rederived; it is a bilinear equation which, it turns out, can be recast in the action conservation form. It is shown that this action conservation equation is in fact equivalent to the action conservation law obtained from Lagrangian treatments (Dewar, 1970; Jacques. 1977a, b). RP BARNES, A (reprint author), NASA, THEORET STUDIES BRANCH, SST 245-3, MOFFETT FIELD, CA 94035 USA. NR 18 TC 29 Z9 29 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1992 VL 97 IS A8 BP 12105 EP 12112 DI 10.1029/92JA00996 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH648 UT WOS:A1992JH64800007 ER PT J AU KLIMAS, AJ BAKER, DN ROBERTS, DA FAIRFIELD, DH BUCHNER, J AF KLIMAS, AJ BAKER, DN ROBERTS, DA FAIRFIELD, DH BUCHNER, J TI A NONLINEAR DYNAMIC ANALOG MODEL OF GEOMAGNETIC-ACTIVITY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND CONTROL; AL TIME-SERIES; PLASMA SHEET; COLLISIONLESS CONDUCTIVITY; MAGNETOSPHERIC SUBSTORMS; EARTHS MAGNETOTAIL; STRANGE ATTRACTORS; BOUNDARY-LAYER; TAIL; AE AB The solar wind-magnetosphere interaction is discussed within the framework of deterministic nonlinear dynamics. Linear prediction filter studies have shown that the magnetospheric response to energy transfer from the solar wind contains both directly driven and unloading components. These studies have also shown that the response is significantly nonlinear and. thus, the filter technique and other correlative techniques cannot give a complete description of that response. Phase space reconstruction studies have shown that the evolution of the nonlinear solar wind-magnetosphere system is dominated by only a few degrees of freedom; the system approaches a low-dimensional attractor on which its behavior can be described using a relatively simple nonlinear dynamical model. An earlier dripping faucet analogue model of the low-dimensional solar wind-magnetosphere system is briefly reviewed, and then a plasma physical counterpart to that model is constructed. A Faraday loop in the magnetotail is considered, and the relationship of electric potentials on the loop to changes in the magnetic flux threading the loop is developed. This approach leads to a model of geomagnetic activity which is similar to the earlier mechanical model but described in terms of the geometry and plasma contents of the magnetotail. The model is best characterized as an elementary time-dependent global convection model. The convection evolves within a magnetotail shape that varies in a prescribed manner in response to the dynamical evolution of the convection. The result is a nonlinear model capable of exhibiting a transition from regular to chaotic loading and unloading. The behavior of the model under steady loading and also some elementary forms of time-dependent loading is discussed. The model appears to properly account for all macrophysical aspects of magnetotail geomagnetic activity, it incorporates both the directly driven and the unloading components of geomagnetic activity, and it includes, in a fundamental way, the inherent nonlinearity of the solar wind-magnetosphere interaction. C1 MAX PLANCK INST EXTRATERRESTR PHYS,BERLIN,GERMANY. RP KLIMAS, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Buechner, Joerg/B-1213-2009; Roberts, Dana/D-4625-2012 NR 58 TC 120 Z9 120 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1992 VL 97 IS A8 BP 12253 EP 12266 DI 10.1029/92JA00794 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH648 UT WOS:A1992JH64800019 ER PT J AU BURTON, ME SISCOE, GL SMITH, EJ AF BURTON, ME SISCOE, GL SMITH, EJ TI SHAPES OF STRONG SHOCK FRONTS PROPAGATING THROUGH THE CORONAL STREAMER BELT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Note ID SOLAR-WIND AB A strong shock that would propagate spherically from the Sun were the solar wind homogeneous instead warps as it refracts and shears through inhomogeneities in solar wind density and velocity. The inhomogeneities can be disordered or ordered by quasi-permanent coronal structures such as coronal holes and the coronal streamer belt. Distortions caused by interacting solar wind streams from coronal holes have been studied. Where colliding streams build density ridges, the shock slows, producing marked localized dimples (concave outward) in the shock front. Here we note that a similar dimple results from the high-density, low-velocity inhomogeneity that distinguishes the coronal streamer belt. That is, a concave outward dimple characterizes the part of the shock that crosses the belt. First, to illustrate this effect, we apply the linearized hydrodynamic model that reveals shock dimples at density ridges of colliding streams. Then, to test the effect, we present normals of the eight shocks we could independently assess to be within the expected range of influence of the belt. Six of the eight shocks showed the predicted distortion. The null hypothesis would give the same result in 1 out of 14 tries. Finally, we note that the dimple shape induces a postshock confluence in the center of the belt of material pushed centerward from the top and bottom of the belt. We suggest this confluence of material might drive field line reconnection at the heliospheric current sheet in the center of the belt, as MHD simulations have observed. C1 UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. RP BURTON, ME (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 15 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1992 VL 97 IS A8 BP 12283 EP 12286 DI 10.1029/92JA00837 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JH648 UT WOS:A1992JH64800024 ER PT J AU SIEGEL, R SPUCKLER, CM AF SIEGEL, R SPUCKLER, CM TI EFFECT OF INDEX OF REFRACTION ON RADIATION CHARACTERISTICS IN A HEATED ABSORBING, EMITTING, AND SCATTERING LAYER SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Note DE RADIATION C1 NASA, LEWIS RES CTR, HEAT TRANSFER BRANCH, CLEVELAND, OH 44135 USA. RP SIEGEL, R (reprint author), NASA, LEWIS RES CTR, LEWIS RES ACAD, CLEVELAND, OH 44135 USA. NR 13 TC 16 Z9 16 U1 0 U2 2 PU ASME PI NEW YORK PA TWO PARK AVE, NEW YORK, NY 10016-5990 USA SN 0022-1481 EI 1528-8943 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD AUG PY 1992 VL 114 IS 3 BP 781 EP 784 DI 10.1115/1.2911352 PG 4 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JL491 UT WOS:A1992JL49100037 ER PT J AU WHITTENBERGER, JD AF WHITTENBERGER, JD TI MECHANICAL-PROPERTIES OF HAYNES (R) ALLOY-188 AFTER EXPOSURE TO LIF-22CAF2, AIR, AND VACUUM AT 1093-K FOR PERIODS UP TO 10,000 HOURS SO JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE LA English DT Article AB As part of a program to provide reassurance that the cobalt-base superalloy Haynes(R) Alloy 188 can adequately contain a LiF-CaF2 eutectic thermal energy storage salt, 4900- and 10,000-hr exposures of Haynes(R) Alloy 188 to LiF-22CaF2, its vapor, vacuum, and air at 1093 K have been undertaken. Following such exposures, the microstructure has been characterized and the 77 to 1200 K tensile properties measured. In addition, 1050 K vacuum creep-rupture testing of as-received and molten salt- and vacuum-exposed samples has been undertaken. Although slight degradation of the mechanical properties of Haynes(R) Alloy 188 due to prior exposure was observed, basically none of the losses could be ascribed to a particular environment. Hence, observed decreases in properties are due to thermal aging effects, not corrosive attack. In view of these findings, Haynes(R) Alloy 188 is still deemed to be suitable for containment of the eutectic LiF-CaF2 thermal energy storage media. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 8 TC 11 Z9 11 U1 2 U2 5 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 1059-9495 J9 J MATER ENG PERFORM JI J. Mater. Eng. Perform. PD AUG PY 1992 VL 1 IS 4 BP 469 EP 482 DI 10.1007/BF02682684 PG 14 WC Materials Science, Multidisciplinary SC Materials Science GA JV732 UT WOS:A1992JV73200002 ER PT J AU PATTERSON, JD GOBBA, WA LEHOCZKY, SL AF PATTERSON, JD GOBBA, WA LEHOCZKY, SL TI ELECTRON-MOBILITY IN N-TYPE HG1-XCDXTE AND HG1-XZNXTE ALLOYS SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID DISORDER SCATTERING; CARRIER CONCENTRATION; MIXED-CRYSTALS; TRANSPORT; HGZNTE; SEMICONDUCTORS; APPROXIMATION; IMPURITY; HGCDTE; STATES AB We have calculated the mobility of electrons in n-type Mercury Cadmium Telluride (MCT) and compared it to a calculation of the mobility of electrons in n-type Mercury Zinc Telluride (MZT) with nearly the same energy gap and with the same number of donors and acceptors. We also compared the results of the MZT calculation with experiment. We found for equivalent energy gaps that the mobilities in the two compounds (MCT, MZT) were nearly the same. The calculations for both MCT and MZT were based on the best set of material parameters that we could compile from the literature. Using these parameters, the comparison with experiment for MZT yielded good results. Since MZT is harder and structurally more stable with respect to Hg retention than MCT, the possibility of equivalent mobility for MCT and MZT is significant. This calculation is one of the first extensive calculations of the mobility of MZT, and we compared it with another which appeared to be less extensive. Our calculation involves scattering of the electrons by longitudinal optic phonons, acoustic phonons, ionized impurities, holes, and compositional disorder. Since not all of these interactions can be approximated by elastic scattering, the corresponding Boltzmann equation was solved by a variational principle. We also discuss directions for future work. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP PATTERSON, JD (reprint author), FLORIDA INST TECHNOL,DEPT PHYS & SPACE SCI,MELBOURNE,FL 32901, USA. NR 49 TC 7 Z9 7 U1 0 U2 0 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD AUG PY 1992 VL 7 IS 8 BP 2211 EP 2218 DI 10.1557/JMR.1992.2211 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA JH823 UT WOS:A1992JH82300033 ER PT J AU HAMPTON, RW NELSON, DV AF HAMPTON, RW NELSON, DV TI ON THE USE OF THE HOLE-DRILLING TECHNIQUE FOR RESIDUAL-STRESS MEASUREMENTS IN THIN PLATES SO JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB The strain gage blind hole-drilling technique may be used to determine residual stresses at and below the surface of components. In this paper, the hole-drilling analysis methodology for thick plates is reviewed, and experimental data are used to evaluate the methodology and to assess its applicability to thin plates. Data on the effects of gage pattern, surface preparation, hole spacing, hole eccentricity, and stress level are also presented. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. RP HAMPTON, RW (reprint author), NASA,AMES RES CTR,TEST ENGN & ANAL BRANCH,MOFFETT FIELD,CA 94035, USA. NR 22 TC 7 Z9 7 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-9930 J9 J PRESS VESS-T ASME JI J. Press. Vessel Technol.-Trans. ASME PD AUG PY 1992 VL 114 IS 3 BP 292 EP 299 DI 10.1115/1.2929043 PG 8 WC Engineering, Mechanical SC Engineering GA JK889 UT WOS:A1992JK88900005 ER PT J AU RYAN, RS AF RYAN, RS TI PRACTICES IN ADEQUATE STRUCTURAL DESIGN SO JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article RP RYAN, RS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-9930 J9 J PRESS VESS-T ASME JI J. Press. Vessel Technol.-Trans. ASME PD AUG PY 1992 VL 114 IS 3 BP 300 EP 307 DI 10.1115/1.2929044 PG 8 WC Engineering, Mechanical SC Engineering GA JK889 UT WOS:A1992JK88900006 ER PT J AU RHATIGAN, JL CHRISTIANSEN, EL FLEMING, ML AF RHATIGAN, JL CHRISTIANSEN, EL FLEMING, ML TI ON PROTECTION OF FREEDOMS SOLAR DYNAMIC RADIATOR FROM THE ORBITAL DEBRIS ENVIRONMENT .1. PRELIMINARY-ANALYSIS AND TESTING SO JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article AB A great deal of experimentation and analysis has been performed to quantify penetration thresholds of components which will experience orbital debris impacts. Penetration has been found to depend upon mission-specific parameters such as orbital altitude, inclination, and orientation of the component; and upon component specific parameters such as material, density, and the geometry particular to its shielding. Experimental results are highly dependent upon shield configuration and cannot be extrapolated with confidence to alternate shield configurations. Also, current experimental capabilities are limited to velocities which only approach the lower limit of predicted orbital debris velocities. Therefore, prediction of the penetrating particle size for a particular component having a complex geometry remains highly uncertain. This paper describes the approach developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeroid and space debris impacts. Preliminary analyses are presented to quantify the solar dynamic radiator survivability, and include the type of particle and particle population expected to defeat the radiator bumpering (i.e., penetrate a fluid flow tube). Results of preliminary hypervelocity impact testing performed on radiator panel samples (in the 6 to 7 km/sec velocity range) are also presented. Plans for further analyses and testing are discussed. These efforts are expected to lead to a radiator design which will perform to Space Station Freedom requirements o ver the expected lifetime. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LTV MISSILES & ELECTR,DALLAS,TX 75265. RP RHATIGAN, JL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 15 TC 0 Z9 0 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0199-6231 J9 J SOL ENERG-T ASME JI J. Sol. Energy Eng. Trans.-ASME PD AUG PY 1992 VL 114 IS 3 BP 135 EP 141 DI 10.1115/1.2929996 PG 7 WC Energy & Fuels; Engineering, Mechanical SC Energy & Fuels; Engineering GA JJ891 UT WOS:A1992JJ89100001 ER PT J AU RHATIGAN, JL CHRISTIANSEN, EL FLEMING, ML AF RHATIGAN, JL CHRISTIANSEN, EL FLEMING, ML TI ON PROTECTION OF FREEDOMS SOLAR DYNAMIC RADIATOR FROM THE ORBITAL DEBRIS ENVIRONMENT .2. FURTHER TESTING AND ANALYSIS SO JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article AB Recent progress to better understand the environmental threat of micrometeoroid and space debris to the solar dynamic radiator for the Space Station Freedom power system is reported. The objective was to define a design which would perform to survivability requirements over the expected lifetime of the radiator. A previous paper described the approach developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeoroid and space debris impacts. Preliminary analyses were presented to quantify the solar dynamic radiator survivability. These included the type of particle and particle population expected to defeat the radiator bumpering. Results of preliminary hypervelocity impact (HVI) testing performed on radiator panel samples were also presented. This paper presents results of a more extensive test program undertaken to further define the response of the solar dynamic radiator to HVI. Tests were conducted on representative radiator panels (under ambient, nonoperating conditions) over a range of particle size, particle density, impact angle, and impact velocity. Target parameters were also varied. Data indicate that analytical penetration predictions are conservative (i.e., pessimistic) for the specific configuration of the solar dynamic radiator. Test results are used to define more rigorously the solar dynamic radiator reliability with respect to HVI. Test data, analyses, and survivability results are presented. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LTV MISSILES & ELECTR CORP,DALLAS,TX 75265. RP RHATIGAN, JL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 TC 0 Z9 0 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0199-6231 J9 J SOL ENERG-T ASME JI J. Sol. Energy Eng. Trans.-ASME PD AUG PY 1992 VL 114 IS 3 BP 142 EP 149 DI 10.1115/1.2929997 PG 8 WC Energy & Fuels; Engineering, Mechanical SC Energy & Fuels; Engineering GA JJ891 UT WOS:A1992JJ89100002 ER PT J AU POWELL, CA AF POWELL, CA TI 2ND INTERNATIONAL-CONGRESS ON RECENT DEVELOPMENTS IN AIR-BORNE AND STRUCTURE-BORNE SOUND VIBRATION SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Editorial Material RP POWELL, CA (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 463,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD AUG PY 1992 VL 92 IS 2 BP 1188 EP 1189 DI 10.1121/1.404004 PN 1 PG 2 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA JG992 UT WOS:A1992JG99200063 ER PT J AU HENKEL, DP WOOD, JD AF HENKEL, DP WOOD, JD TI ACOUSTIC-EMISSION FROM A SOLIDIFYING ALUMINUM-LITHIUM ALLOY SO MATERIALS EVALUATION LA English DT Article DE ACOUSTIC EMISSION; AEROSPACE; ALUMINUM ALLOY; CASTING; DEFECT CHARACTERIZATION; MICROSTRUCTURE; NONDESTRUCTIVE EVALUATION; POROSITY; SOLIDIFICATION; WAVE-FORM PROCESSING AB Physical phenomena associated with the solidification of an AA2090 aluminum-lithium (Al-Li) alloy have been characterized by acoustic emission (AE) techniques. Repeatable patterns of AE activity as a function of solidification time have been recorded and explained for ultrahigh-purity (UHP) aluminum and an Al-4.7 wt % Cu binary alloy, in addition to the AA2090 Al-Li alloy, by the complementary use of thermal, AE, and metallographic techniques. Results show the following. (1) The solidification of UHP aluminum produces one discrete period of high AE activity as the last 10 percent of solid forms. A model is presented that attributes this to the release of strain energy imposed by internal stresses developed during grain-boundary formation. (2) The Al-Li alloy and the Al-Cu alloy each generate two discrete periods of AE activity as they solidify. One period occurs as the last 10 percent of solid forms, similar to the case of UHP aluminum; the other period occurs as the first 20 percent of solid forms, which does not occur with the UHP aluminum. The activity at the beginning of solidification is attributed to interdendritic porosity and solidification cracking and the activity at the end to grain-boundary formation. (3) AE alone was ineffective in identifying source mechanisms during solidification. AE signal characteristics from porosity and grain-boundary formation were indistinguishable using conventional AE and waveform analysis. It was only through the complementary use of AE, cooling curves; and microstructural analysis that the sources were determined. C1 LEHIGH UNIV,DEPT MAT SCI & ENGN,BETHLEHEM,PA 18015. ANALYT SERV & MAT INC,HAMPTON,VA. LEHIGH UNIV,ADV TECHNOL CTR LARGE STRUCT SYST,BETHLEHEM,PA 18015. COLL WILLIAM & MARY,APPL SCI PROGRAM,WILLIAMSBURG,VA 23185. RP HENKEL, DP (reprint author), NASA,LANGLEY RES CTR,NDE LAB,MAIL STOP 231,HAMPTON,VA 23665, USA. NR 13 TC 0 Z9 0 U1 1 U2 1 PU AMER SOC NON-DESTRUCTIVE TEST PI COLUMBUS PA 1711 ARLINGATE LANE PO BOX 28518, COLUMBUS, OH 43228-0518 SN 0025-5327 J9 MATER EVAL JI Mater. Eval. PD AUG PY 1992 VL 50 IS 8 BP 972 EP 977 PG 6 WC Materials Science, Characterization & Testing SC Materials Science GA JJ799 UT WOS:A1992JJ79900013 ER PT J AU GOLDEN, CL DUDLEY, GA AF GOLDEN, CL DUDLEY, GA TI STRENGTH AFTER BOUTS OF ECCENTRIC OR CONCENTRIC ACTIONS SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Article DE LENGTHENING AND SHORTENING ACTIONS; DELAYED ONSET MUSCLE DAMAGE ID SKELETAL-MUSCLE FIBERS; LENGTHENING CONTRACTIONS; REFLEX INHIBITION; EXERCISE; INJURY; VOLUNTARY; DAMAGE; PAIN; ADAPTATION; SARCOMERE AB This study examined the influence of an initial bout of eccentric or concentric actions and a subsequent bout of eccentric actions on muscular strength. Twenty-four healthy males, 24-45 yr old, were placed in three groups that performed eccentric actions in bouts 1 and 2 (ECC/ECC, N = 8), concentric actions in bout 1, and eccentric actions in bout 2 (CON/ECC, N = 8) or served as controls (N = 8). Bouts involved unilateral actions with the left and right quadriceps femoris. Ten sets of 10 repetitions with an initial resistance equal to 85% of the eccentric or concentric one repetition maximum (1 RM) were performed for each bout. Three minutes of rest were given between sets and 3 wk between bouts. Two weeks before bout 1 and 1, 4, 7, and 10 d after bouts 1 and 2, eccentric and concentric 1 RM were measured for the fight quadriceps femoris and a speed-torque relation established for the left quadriceps femoris. Eccentric and concentric 1 RM decreased (P < 0.05) 32% 1 d after bout 1 for group ECC/ECC. The speed-torque relation was down-shifted (P < 0.05) 38%. Eccentric 1 RM and eccentric and isometric torque returned to normal 6 d later. Concentric 1 RM and torque at 3.14 rad.s-1 had not recovered on day 10 (-7 % for both, P < 0.05). Decreases in strength after bout 2 for group ECC/ECC only occurred on day 1 (-9% for concentric 1 RM and 16% downshift of the speed-torque relation). Group CON/ECC showed the opposite responses; marked decreases in strength after bout 2 but not bout 1. The results indicate that the initial decrease in strength after performance of a novel bout of eccentric exercise is comparable for eccentric, concentric, and isometric muscle actions. Recovery of strength, however, appears to occur more rapidly for eccentric and isometric actions. They suggest that performance of a prior bout of eccentric but not concentric actions, as done in this study, can essentially eradicate decreases in strength after a subsequent bout of eccentric exercise. It is suggested that neural factors are, in part, responsible for adaptations to eccentric exercise. C1 NASA,BIOMED OPERAT & RES OFF,MAIL CODE MD-M,KENNEDY SPACE CTR,FL 32899. UNIV FLORIDA,DEPT EXERCISE & SPORTS SCI,GAINESVILLE,FL 32611. NR 29 TC 74 Z9 74 U1 0 U2 4 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD AUG PY 1992 VL 24 IS 8 BP 926 EP 933 PG 8 WC Sport Sciences SC Sport Sciences GA JH702 UT WOS:A1992JH70200015 PM 1406179 ER PT J AU ZAKHEM, R WEIDMAN, PD DEGROH, HC AF ZAKHEM, R WEIDMAN, PD DEGROH, HC TI ON THE DRAG OF MODEL DENDRITE FRAGMENTS AT LOW REYNOLDS-NUMBER SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID GRAVITY AB An experimental study of low Reynolds number drag on laboratory models of dendrite fragments has been conducted. The terminal velocities of the dendrites undergoing free fall along their axis of symmetry were measured in a large Stokes flow facility. Corrections for wall interference give nearly linear drag vs Reynolds number curves. Corrections for both wall interference and inertia effects show that the dendrite Stokes settling velocities are always less than that of a sphere of equal mass and volume. In the Stokes limit, the settling speed ratio is found to correlate well with the primary dendrite arm aspect ratio and a second dimensionless shape parameter which serves as a measure of the fractal-like nature of the dendrite models. These results can be used to estimate equiaxed grain velocities and distance of travel in metal castings. The drag measurements may be used in numerical codes to calculate the movement of grains in a convecting melt in an effort to determine macrosegregation patterns caused by the sink/float mechanism. C1 NASA,LEWIS RES CTR,DEPT PROC SCI & TECHNOL,DIV MAT,CLEVELAND,OH 44135. RP ZAKHEM, R (reprint author), UNIV COLORADO,DEPT MECH ENGN,BOULDER,CO 80309, USA. NR 27 TC 16 Z9 16 U1 0 U2 4 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD AUG PY 1992 VL 23 IS 8 BP 2169 EP 2181 DI 10.1007/BF02646010 PG 13 WC Materials Science, Multidisciplinary SC Materials Science GA JG400 UT WOS:A1992JG40000010 ER PT J AU SIMONS, RN PERL, TD LEE, RQ AF SIMONS, RN PERL, TD LEE, RQ TI NEW COPLANAR WAVE-GUIDE FEED NETWORK FOR 2X2 LINEARLY TAPERED SLOT ANTENNA SUBARRAY SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE COPLANAR WAVE-GUIDE; LINEARLY TAPERED SLOT ANTENNA; SLOT LINE; ARRAY ANTENNA AB A new technique for exciting 2 x 2 subarray of linearly tapered slot antennas (LTSAs) with coplanar waveguide (CPW) is presented. rf power is coupled to each element through a CPW-to-slotline transition by a coax-to-CPW in-phase four-way radial power divider. The transition and the power divider are coupled by a novel nonplanar CPW right-angle bend. Measured results at 18 GHz show excellent radiation patterns and return-loss characteristics. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD AUG PY 1992 VL 5 IS 9 BP 420 EP 423 DI 10.1002/mop.4650050907 PG 4 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA JA600 UT WOS:A1992JA60000006 ER PT J AU DAY, CSR FABIAN, AC ROSS, RR AF DAY, CSR FABIAN, AC ROSS, RR TI A SEARCH FOR THE IRON-ABSORPTION EDGE IN THE TAIL OF AN X-RAY BURST FROM X1636-53 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE LINE, FORMATION; STARS, ABUNDANCES; STARS, ATMOSPHERES; STARS, INDIVIDUAL, X1636-53; STARS, NEUTRON; X-RAYS, STARS ID NEUTRON-STARS; MODEL ATMOSPHERES; SPECTRA; EMISSION; LINES AB Model atmosphere calculations of the spectrum of a neutron star cooling after an X-ray burst show that the photoelectric edge of iron should be prominent. We find no clear evidence for such a redshifted feature in the spectrum of a burst from X1636-53 and conclude that the iron abundance there must be less than 0.3 solar. Unless the iron abundance of the surface matter on the neutron star is highly time-dependent, our result argues against the 4.1-keV absorption line seen in some bursts from X1636-53 by Waki et al. being due to iron. We note that the iron edge will be a powerful diagnostic of the surface redshift of the neutron star in burst sources where the iron abundance is more nearly solar. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. UNIV CAMBRIDGE,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. COLL HOLY CROSS,DEPT PHYS,WORCESTER,MA 01610. RP DAY, CSR (reprint author), INST SPACE & ASTRONAUT SCI,3-1-1 YOSHINODAI,SAGAMIHARA,KANAGAWA 229,JAPAN. NR 22 TC 8 Z9 8 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 1 PY 1992 VL 257 IS 3 BP 471 EP 475 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF819 UT WOS:A1992JF81900014 ER PT J AU CHAO, WC CHANG, LP AF CHAO, WC CHANG, LP TI DEVELOPMENT OF A 4-DIMENSIONAL VARIATIONAL ANALYSIS SYSTEM USING THE ADJOINT METHOD AT GLA .1. DYNAMICS SO MONTHLY WEATHER REVIEW LA English DT Article ID CONJUGATE-GRADIENT METHODS; LARGE-SCALE MINIMIZATION; METEOROLOGICAL OBSERVATIONS; OBJECTIVE ANALYSIS; VORTICITY EQUATION; ASSIMILATION; CONSTRAINTS; ALGORITHMS; STORAGE AB Recent developments in the field of data assimilation have pointed to variational analysis (essentially least-squares fitting of a model solution to observed data) using the adjoint method as a new direction that holds the potential of major improvements over the current optimal interpolation (OI) method. The shortcomings of the existing OI analysis method, such as the questionable basic assumptions underlying some of the statistical formulations and the linearity between the analysis and the observation, do not exist in variational analysis. Moreover, variational analysis, by fitting a model solution to data, has the potential of avoiding the long-standing spinup problem in numerical weather prediction. Finally, when the resulting analysis is used as the initial condition for forecasting, since initialization will be performed internally to the analysis procedure, no separate initialization procedure is required before forecast starts. This paper describes the initial effort in the development of a four-dimensional variational analysis system. Although the development is based on the Goddard Laboratory for Atmospheres General Circulation Model (GLA GCM), the methods and procedures described in this paper can be applied to any model. The adjoint code that computes the gradients needed in the analysis can be written directly from the GCM code. An easy error-detection technique was devised in the construction of the adjoint model. Also, a method of determining the weights and the preconditioning scales for the cases where model-generated data, which are error free, are used as observation is proposed. Two test experiments show that the dynamics part of the system has been successfully completed. A limited comparison of two minimization codes was conducted. The procedures presented in this work are general and can be applied to various variational and sensitivity studies. C1 GEN SCI CORP,LAUREL,MD. RP CHAO, WC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GODDARD LAB ATMOSPHERES,CODE 913,GREENBELT,MD 20771, USA. NR 33 TC 43 Z9 53 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD AUG PY 1992 VL 120 IS 8 BP 1661 EP 1673 DI 10.1175/1520-0493(1992)120<1661:DOAFDV>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JF238 UT WOS:A1992JF23800012 ER PT J AU NAMIOKA, T KOIKE, M AF NAMIOKA, T KOIKE, M TI ANALYTICAL REPRESENTATION OF SPOT DIAGRAMS AND ITS APPLICATION TO THE DESIGN OF MONOCHROMATORS SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 7TH NATIONAL CONF ON SYNCHROTRON RADIATION INSTRUMENTATION CY OCT 28-31, 1991 CL LOUISIANA STATE UNIV, BATON ROUGE, LA SP MAXWELL LABS, BROBECK DIV HO LOUISIANA STATE UNIV ID GRATINGS AB A new method has been developed for the design of a highly sophisticated Monochromator equipped with a holographic or a ruled grating with variable spacing and curved grooves. The method utilizes analytical expression of the spot diagrams, as well as a merit function which closely represents the rms spread of the spots formed when an infinite number of rays are traced. Unlike other design methods based on the light path function, the present method takes into account all the possible aberrations (up to third order) in spectral images, the ruled area, and the slit height. Also given are design examples of a high-resolution VUV monochromator. C1 LAWRENCE BERKELEY LAB,CTR X RAY OPT,BERKELEY,CA 94720. RP NAMIOKA, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,MC 7171,GREENBELT,MD 20771, USA. NR 12 TC 17 Z9 18 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD AUG 1 PY 1992 VL 319 IS 1-3 BP 219 EP 227 DI 10.1016/0168-9002(92)90557-K PG 9 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA JF674 UT WOS:A1992JF67400036 ER PT J AU STAHLE, CK OSHEROFF, D KELLEY, RL MOSELEY, SH SZYMKOWIAK, AE AF STAHLE, CK OSHEROFF, D KELLEY, RL MOSELEY, SH SZYMKOWIAK, AE TI ADAPTING CALORIMETRIC X-RAY-DETECTORS FOR COMPTON-SCATTERING EXPERIMENTS PERFORMED AT HIGH-ENERGIES SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 7TH NATIONAL CONF ON SYNCHROTRON RADIATION INSTRUMENTATION CY OCT 28-31, 1991 CL LOUISIANA STATE UNIV, BATON ROUGE, LA SP MAXWELL LABS, BROBECK DIV HO LOUISIANA STATE UNIV ID HIGH-RESOLUTION SPECTROSCOPY; THERMAL DETECTORS; SUPERCONDUCTORS; SPECTROMETERS; QUASIPARTICLE AB Motivated by the need for improved resolution in Compton scattering experiments performed with high energy X-rays, we have developed a high resolution spectrometer. We have adapted calorimetric X-ray detectors, produced at Goddard Space Flight Center for X-rays around 6 keV, to Compton scattering research using synchrotron radiation near 40 keV. Such a detector is operated below 0.1 K and determines X-ray energies by measuring the temperature increase which results from the absorption of a single X-ray photon. We have investigated a number of materials as candidates for the overlayer which is affixed to a device in order to absorb the X-rays and transfer their energy to phonons. Using Sn absorbers, we have achieved a resolution of 90 eV at 32 keV. The apparatus was brought to a wiggler beam line at the Stanford Synchrotron Radiation Laboratory, where we were able to measure Compton profiles of Si for the (100) and (111) directions. The difference reproduced the previously measured anisotropy, but the measurement was limited by the low number of total counts and by a degradation in resolution experienced during operation at the synchrotron. This experiment illustrates the feasibility of using such a system for Compton scattering research. We expect that future improvements to the detectors and to the supporting apparatus will make higher resolution measurements possible. C1 STANFORD SYNCHROTRON RADIAT LAB,STANFORD,CA 94309. STANFORD UNIV,DEPT PHYS,STANFORD,CA 94305. RP STAHLE, CK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 666,GREENBELT,MD 20771, USA. RI Kelley, Richard/K-4474-2012 NR 13 TC 6 Z9 6 U1 2 U2 5 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 AUG 1 PY 1992 VL 319 IS 1-3 BP 393 EP 399 DI 10.1016/0168-9002(92)90584-Q PG 7 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA JF674 UT WOS:A1992JF67400063 ER PT J AU BIANCO, R RAPP, RA JACOBSON, NS AF BIANCO, R RAPP, RA JACOBSON, NS TI VOLATILE SPECIES IN HALIDE-ACTIVATED DIFFUSION COATING PACKS SO OXIDATION OF METALS LA English DT Article DE PACK CEMENTATION; ALUMINIDE DIFFUSION COATINGS; METAL HALIDE VAPORS ID IRON; ALUMINIZATION; KINETICS; AL AB An atmospheric pressure sampling mass spectrometer was used to identify the vapor species generated in a halide-activated, cementation pack. Pack powder mixtures containing a Cr-Al binary masteralloy powder, an NH4Cl activator salt, and either ZrO2 or Y2O3 (or neither) were analyzed at 1000-degrees-C. Both equilibrium calculations for the pack and mass spectrometer results indicated that volatile AlClx and CrCly species were generated by the pack powder mixture; in packs containing the reactive element oxide, volatile ZrClz and YClw species were formed by the conversion of their oxide sources. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BIANCO, R (reprint author), OHIO STATE UNIV,DEPT MAT SCI & ENGN,COLUMBUS,OH 43210, USA. RI Jacobson, Nathan/A-9411-2009 NR 33 TC 25 Z9 25 U1 0 U2 4 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0030-770X J9 OXID MET JI Oxid. Met. PD AUG PY 1992 VL 38 IS 1-2 BP 33 EP 43 DI 10.1007/BF00665043 PG 11 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA JN325 UT WOS:A1992JN32500002 ER PT J AU DOYCHAK, J NESBITT, JA NOEBE, RD BOWMAN, RR AF DOYCHAK, J NESBITT, JA NOEBE, RD BOWMAN, RR TI OXIDATION OF AL2O3 CONTINUOUS FIBER-REINFORCED NIAL COMPOSITES SO OXIDATION OF METALS LA English DT Article DE INTERMETALLIC-MATRIX COMPOSITES; OXIDATION; NIAL; FIBER/MATRIX INTERFACES AB The 1200-degrees-C and 1300-degrees-C isothermal and cyclic oxidation behavior of Al2O3 continuous fiber (Saphikon(TM))-reinforced/NiAl composites were studied Oxidation resulted in formation of Al2O3 external scales in a similar manner as scales formed on monolithic NiAl. The isothermal oxidation of an Al2O3/NiAl composite resulted in oxidation of the matrix along the fiber/matrix interface near the fiber ends. This oxide acted as a wedge between the fiber and matrix, and, under cyclic oxidation conditions, led to further oxidation along the fiber lengths and eventual cracking of the composite. The oxidation behavior or composites in which the Al2O3 fibers were sputter coated with nickel prior to processing was much more severe. This was attributed to open channels around the fibers which formed during processing most likely as a result of the diffusion of the nickel coating into the matrix. RP DOYCHAK, J (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 16 TC 15 Z9 15 U1 1 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0030-770X J9 OXID MET JI Oxid. Met. PD AUG PY 1992 VL 38 IS 1-2 BP 45 EP 72 DI 10.1007/BF00665044 PG 28 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA JN325 UT WOS:A1992JN32500003 ER PT J AU WILSON, GS BACKLUND, PW AF WILSON, GS BACKLUND, PW TI MISSION TO PLANET EARTH SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article AB Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment. RP WILSON, GS (reprint author), NASA,DIV EARTH SCI & APPLICAT,WASHINGTON,DC 20546, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD AUG PY 1992 VL 58 IS 8 BP 1133 EP 1135 PG 3 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA JF232 UT WOS:A1992JF23200027 ER PT J AU NELLIS, MD LULLA, K AF NELLIS, MD LULLA, K TI REMOTE-SENSING AND THE ASSOCIATION OF AMERICAN GEOGRAPHERS SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article AB The Remote Sensing Specialty Group (RSSG) of the Association of American Geographers has played an important role in fostering understanding of remote sensing science. Through special awards, liaison with other professional organizations, fund raising, development of special meeting programs and workshops, as well as special publications, the RSSG contributes in many ways towards the advancement of remote sensing research. Special publications by RSSG members have served to articulate the important role geographers have played and will continue to play in refining the science of remote sensing. C1 NASA,LYNDON B JOHNSON SPACE CTR,FLIGHT SCI SUPPORT OFF,HOUSTON,TX 77058. RP NELLIS, MD (reprint author), KANSAS STATE UNIV AGR & APPL SCI,DEPT GEOG,MANHATTAN,KS 66506, USA. NR 26 TC 0 Z9 0 U1 0 U2 1 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD AUG PY 1992 VL 58 IS 8 BP 1147 EP 1148 PG 2 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA JF232 UT WOS:A1992JF23200031 ER PT J AU SHORT, NM AF SHORT, NM TI SPACE-90 SATELLITE LAUNCH HISTORY SOFTWARE SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Software Review RP SHORT, NM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CTR NATL SPACE SCI DATA,CODE 934,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD AUG PY 1992 VL 58 IS 8 BP 1207 EP 1208 PG 2 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA JF232 UT WOS:A1992JF23200050 ER PT J AU RUBINSTEIN, R BARTON, JM AF RUBINSTEIN, R BARTON, JM TI RENORMALIZATION-GROUP ANALYSIS OF THE REYNOLDS STRESS TRANSPORT-EQUATION SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID TURBULENT SHEAR FLOWS; REPRESENTATION; DIFFUSION; CLOSURE; MODELS AB The pressure-gradient-velocity correlation and return to isotropy term in the Reynolds stress transport equation are analyzed using the Yakhot-Orszag renormalization group. The perturbation series for the relevant correlations, evaluated to lowest order in the epsilon-expansion of the Yakhot-Orszag theory, are infinite series in tensor product powers of the mean velocity gradient and its transpose. Formal lowest-order Pade approximations to the sums of these series produce a rapid pressure strain model of the form proposed by Launder et al. [J. Fluid Mech. 68, 537 (1975)], and a return to isotropy model of the form proposed by Rotta [Z. Phys. 129, 547 (1951)]. In both cases, the model constants are computed theoretically. The predicted Reynolds stress ratios in simple shear flows are evaluated and compared with experimental data. The possibility is discussed of deriving higher-order nonlinear models by approximating the sums more accurately. C1 NASA,LEWIS RES CTR,CTR MODELING TURBULENCE & TRANSIT,CLEVELAND,OH 44135. RP RUBINSTEIN, R (reprint author), SVERDRUP TECHNOL INC,DEPT AEROMECH,CLEVELAND,OH 44135, USA. NR 31 TC 8 Z9 12 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD AUG PY 1992 VL 4 IS 8 BP 1759 EP 1766 DI 10.1063/1.858396 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JE923 UT WOS:A1992JE92300019 ER PT J AU MORRISON, D AF MORRISON, D TI BRILLIANT EYES NOT PART OF NASA ASTEROID WORK SO PHYSICS TODAY LA English DT Letter RP MORRISON, D (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD AUG PY 1992 VL 45 IS 8 BP 11 EP 11 DI 10.1063/1.2809762 PN 1 PG 1 WC Physics, Multidisciplinary SC Physics GA JH095 UT WOS:A1992JH09500004 ER PT J AU AMOEDO, J LEE, D AF AMOEDO, J LEE, D TI MODELING THE UNIAXIAL RATE AND TEMPERATURE-DEPENDENT BEHAVIOR OF AMORPHOUS AND SEMICRYSTALLINE POLYMERS SO POLYMER ENGINEERING AND SCIENCE LA English DT Article ID NECK PROPAGATION; STRAIN-RATE; CONSTITUTIVE EQUATION; PLASTIC-DEFORMATION; TENSILE DEFORMATION; GLASSY POLYMERS; YIELD BEHAVIOR; POLYCARBONATE; POLYPROPYLENE; POLYETHYLENE AB Strain rate and temperature dependent constitutive equations are proposed for polymer materials based on existing isotropic formulations of viscoplasticity. The proposed formulations are capable of simulating some of the important features of deformation behavior of amorphous and semicrystalline polymers. The material model is based on the assumption that the evolution of flow stress is dependent on the rate of deformation, temperature, and an appropriate set of internal variables. The proposed theory is capable of modeling yielding, strain softening, and the orientation hardening exhibited by amorphous polymers. It is also possible to model the initial viscoplastic and subsequent nonlinear hardening behavior shown by semicrystalline polymers at large strains. Uniaxial tensile tests with uniform and hourglass specimens are made at temperatures ranging from 23 to 100-degrees-C and under various crosshead speeds. Both amorphous polycarbonate and semicrystalline polypropylene sheet materials are tested to characterize the stress and strain behavior of these materials and to determine their appropriate material constants. Load relaxation experiments are also conducted to obtain the necessary material constants describing the rate and temperature dependent flow stress behavior of polypropylene. Simulation results compare favorably against experimental data for these polymer materials. C1 RENSSELAER POLYTECH INST,DEPT MECH ENGN AERONAUT ENGN & MECH,TROY,NY 12181. RP AMOEDO, J (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 73 TC 16 Z9 16 U1 0 U2 3 PU SOC PLASTICS ENG INC PI BROOKFIELD CENTER PA 14 FAIRFIELD DR, BROOKFIELD CENTER, CT 06804-0403 SN 0032-3888 J9 POLYM ENG SCI JI Polym. Eng. Sci. PD AUG PY 1992 VL 32 IS 16 BP 1055 EP 1065 DI 10.1002/pen.760321603 PG 11 WC Engineering, Chemical; Polymer Science SC Engineering; Polymer Science GA JL843 UT WOS:A1992JL84300002 ER PT J AU HE, XM RUKER, F CASALE, E CARTER, DC AF HE, XM RUKER, F CASALE, E CARTER, DC TI STRUCTURE OF A HUMAN MONOCLONAL-ANTIBODY FAB FRAGMENT AGAINST GP41 OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article DE ANTIBODY STRUCTURE; AIDS ID 3-DIMENSIONAL STRUCTURE; ESCHERICHIA-COLI; HYPERVARIABLE REGIONS; ANTIGEN COMPLEX; X-RAY; REFINEMENT; PROTEIN; CRYSTALLIZATION; NEURAMINIDASE; RESOLUTION AB The three-dimensional structure of a human monoclonal antibody (Fab), which binds specifically to a major epitope of the transmembrane protein gp41 of the human immunodeficiency virus type 1, has been determined by crystallographic methods to a resolution of 2.7 angstrom. It has been previously determined that this antibody recognizes the epitope SGKLICTTAVPWNAS, belongs to the subclass IgG1 (kappa), and exhibits antibody-dependent cellular cytotoxicity. The quaternary structure of the Fab is in an extended conformation with an elbow bend angle between the constant and variable domains of 175-degrees. Structurally, four of the hypervariable loops can be classified according to previously recognized canonical structures. The third hypervariable loops of the heavy (H3) and light chain (L3) are structurally distinct. Hypervariable loop H3, residues 102H-109H, is unusually extended from the surface. The complementarity-determining region forms a hydrophobic binding pocket that is created primarily from hypervariable loops L3, H3, and H2. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, DIV MICROGRAV SCI & APPLICAT,SPACE SCI LAB, E576 BIOPHYS, HUNTSVILLE, AL 35812 USA. UNIV AGR & FORESTRY, INST APPL MICROBIOL, A-1190 VIENNA, AUSTRIA. NR 39 TC 62 Z9 62 U1 0 U2 2 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD AUG 1 PY 1992 VL 89 IS 15 BP 7154 EP 7158 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JF856 UT WOS:A1992JF85600102 PM 1496010 ER PT J AU ASRAR, G MYNENI, RB CHOUDHURY, BJ AF ASRAR, G MYNENI, RB CHOUDHURY, BJ TI SPATIAL HETEROGENEITY IN VEGETATION CANOPIES AND REMOTE-SENSING OF ABSORBED PHOTOSYNTHETICALLY ACTIVE RADIATION - A MODELING STUDY SO REMOTE SENSING OF ENVIRONMENT LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL COLLOQUIUM ON PHYSICAL MEASUREMENTS AND SIGNATURES IN REMOTE SENSING CY JAN 14-18, 1991 CL COURCHEVEL, FRANCE SP INT SOC PHOTOGRAMMETRY & REMOTE SENSING, CTR NATL ETUDES SPATIALES, EUROPEAN SPACE AGCY, CNRS, INRA, INST FRANCAIS RECH EXPLOITAT MER ID BIDIRECTIONAL SCATTERING; SPECTRAL REFLECTANCE; SOLAR-RADIATION; CORN CANOPIES; LEAVES; LIGHT; CROP AB A large number of previous studies have investigated the possibility of estimating absorbed photosynthetically active radiation (PAR) from spectral reflectance of plant canopies. An important factor not considered in these studies is the case of horizontally heterogeneous plant stands where the ground cover is usually less than 100%. We investigated the relationship between spectral indices and fraction of absorbed PAR in horizontally heterogeneous vegetation canopies with the aid of a three-dimensional radiative transfer model. Canopy reflection at optical wavelengths and PAR absorption was simulated using this model. The errors incurred in using a ID model for calculating the radiation regime of spatially heterogeneous canopies are shown to be significant. Our analysis indicates that the leaf area index of a canopy is less of an instructive parameter than ground cover and clump leaf area index for these canopies. The relationship between normalized difference vegetation index and fraction of absorbed PAR is found to be almost linear and independent of spatial heterogeneity. However, this relationship is sensitive to the reflectance of the soil or background. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,GREENBELT,MD 20771. RP ASRAR, G (reprint author), NASA,MAIL CODE SE,WASHINGTON,DC 20546, USA. RI Myneni, Ranga/F-5129-2012 NR 37 TC 147 Z9 152 U1 1 U2 19 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG-SEP PY 1992 VL 41 IS 2-3 BP 85 EP 103 DI 10.1016/0034-4257(92)90070-Z PG 19 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA JF181 UT WOS:A1992JF18100002 ER PT J AU MYNENI, RB ASRAR, G HALL, FG AF MYNENI, RB ASRAR, G HALL, FG TI A 3-DIMENSIONAL RADIATIVE-TRANSFER METHOD FOR OPTICAL REMOTE-SENSING OF VEGETATED LAND SURFACES SO REMOTE SENSING OF ENVIRONMENT LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL COLLOQUIUM ON PHYSICAL MEASUREMENTS AND SIGNATURES IN REMOTE SENSING CY JAN 14-18, 1991 CL COURCHEVEL, FRANCE SP INT SOC PHOTOGRAMMETRY & REMOTE SENSING, CTR NATL ETUDES SPATIALES, EUROPEAN SPACE AGCY, CNRS, INRA, INST FRANCAIS RECH EXPLOITAT MER ID BIDIRECTIONAL REFLECTANCE; FOREST CANOPY; SCATTERING; MODEL; TRANSPORT; PHOTOSYNTHESIS; DISTRIBUTIONS; EQUATION; LEAVES; LIGHT AB In the application of remote sensing at optical wavelengths to vegetated land surfaces from satellite-borne high-resolution instruments, such as those scheduled for the Earth Observing System, an understanding of the various physical mechanisms that contribute to the measured signal is important. In this context, numerical radiative transfer in three-dimensional coupled medium of atmosphere and vegetation has several applications, as in the development of correction routines for atmospheric perturbations, target information retrieval techniques, study of terrain elevation and adjacency effects, etc. A numerical method for solving the radiative transfer equation in three spatial dimensions was recently developed and analyzed for its numerical behavior. In this article, continued development of the method is reported, including an efficient acceleration algorithm. The reliability of coding and accuracy of the algorithm are evaluated by benchmarking. Parameterization of the method and results of a simulation are presented to document the utility of the code for applications in optical remote sensing studies of vegetated land surfaces. A simple model of the hot spot effect and sample calculations are presented. Finally, the radiative transfer method is tested with experimental data of vegetation canopy reflectance factors at two wavelengths. C1 NASA,WASHINGTON,DC 20546. NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. RP MYNENI, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,MAIL CODE 974,GREENBELT,MD 20771, USA. RI Myneni, Ranga/F-5129-2012 NR 42 TC 63 Z9 65 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG-SEP PY 1992 VL 41 IS 2-3 BP 105 EP 121 DI 10.1016/0034-4257(92)90071-Q PG 17 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA JF181 UT WOS:A1992JF18100003 ER PT J AU LOWMAN, PD AF LOWMAN, PD TI THE SUDBURY STRUCTURE AS A TERRESTRIAL MARE BASIN SO REVIEWS OF GEOPHYSICS LA English DT Review ID COMPLEX; IMPACT; ORIGIN; ONTARIO; CANADA AB This paper reviews the origin, development, and Present status Of the hypothesis that the Sudbury Structure of Ontario, Canada, is a deformed Precambrian impact crater analogous to the circular lunar maria. The petrologic similarity of the maria and terrestrial lopoliths, such as the Bush-veld, Duluth, and Sudbury igneous complexes, was suggested in 1961, assuming these to be extrusive features roofed by their own silicic differentiates. This led to the proposal by R. S. Dietz in 1962 that the Sudbury Structure was a tectonically deformed impact basin, occupied by an extrusive lopolith, and analogous to the small lunar maria. He then searched for and found shatter cones at Sudbury. Discovery of shock metamorphic features in the Onaping Formation by B. M. French in 1967 showed that this formation was a fallback breccia. Detailed studies since the 1970s have further strengthened the impact theory. Isotopic and impact modeling investigations have shown that the Sudbury Igneous Complex may be largely impact melt rather than internally generated magma. The shape and size of the original impact crater are not well known. The absence of compressional deformation of the North Range supports an originally elliptical shape, which has been shown to be similar to those of impact craters on the Moon and Mars. However, field mapping and reflection profiling suggest that much of the present ellipticity may have been produced by northwest directed ductile thrusting concentrated on the South Range and interior of the complex. The size of the original structure is also uncertain. Recent investigations indicate that the present igneous complex is only the central part of a much larger and perhaps multiring structure. The analogy between the Sudbury Structure and lunar maria, though petrologically wrong, is valid to the extent that both classes of structure were initially formed by impact. However, the size and shape of the original crater and the degree to which the Sudbury Intrusive Complex and its ore deposits are impact-generated are still open to debate. RP LOWMAN, PD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,CODE 921,GREENBELT,MD 20771, USA. NR 99 TC 13 Z9 13 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 8755-1209 J9 REV GEOPHYS JI Rev. Geophys. PD AUG PY 1992 VL 30 IS 3 BP 227 EP 243 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JN089 UT WOS:A1992JN08900003 ER PT J AU CAI, W GOTTLIEB, D SHU, CW AF CAI, W GOTTLIEB, D SHU, CW TI ON ONE-SIDED FILTERS FOR SPECTRAL FOURIER APPROXIMATIONS OF DISCONTINUOUS FUNCTIONS SO SIAM JOURNAL ON NUMERICAL ANALYSIS LA English DT Article DE ONE-SIDED FILTER; SPECTRAL METHOD; DISCONTINUOUS FUNCTION AB In this paper the existence of one-sided filters is proved for spectral Fourier approximations of discontinuous functions, which can recover spectral accuracy up to the discontinuity from one side. A least square procedure is used to construct such a filter and is tested on several discontinuous functions numerically C1 BROWN UNIV,DEPT APPL MATH,PROVIDENCE,RI 02912. NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665. RP CAI, W (reprint author), UNIV N CAROLINA,DEPT MATH,CHARLOTTE,NC 28223, USA. RI Shu, Chi-Wang/A-3216-2013 OI Shu, Chi-Wang/0000-0001-7720-9564 NR 13 TC 18 Z9 19 U1 0 U2 2 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 0036-1429 J9 SIAM J NUMER ANAL JI SIAM J. Numer. Anal. PD AUG PY 1992 VL 29 IS 4 BP 905 EP 916 DI 10.1137/0729055 PG 12 WC Mathematics, Applied SC Mathematics GA JG238 UT WOS:A1992JG23800001 ER PT J AU LANARI, L WEN, JT AF LANARI, L WEN, JT TI ASYMPTOTICALLY STABLE SET POINT CONTROL LAWS FOR FLEXIBLE ROBOTS SO SYSTEMS & CONTROL LETTERS LA English DT Article DE PASSIVITY; FLEXIBLE MANIPULATOR; FLEXIBLE BEAM; FLEXIBLE JOINT; LYAPUNOV ANALYSIS ID JOINT ROBOTS AB A general family of asymptotically stabilizing control laws is introduced for a class of nonlinear Hamiltonian systems. The inherent passivity property of this class of systems and the Passivity Theorem are used to show the closed loop input/output stability which is then related to the internal state space stability through an observability condition. Applications of these results include fully actuated robots, flexible-joint robots, and robots with link flexibility. C1 UNIV ROME LA SAPIENZA,DIPARTIMENTO INFORMAT & SISTEMIST,I-00185 ROME,ITALY. RENSSELAER POLYTECH INST,NASA,CTR INTELLIGENT ROBOT SYST SPACE EXPLORAT,TROY,NY 12181. RI Wen, John/B-4474-2008; OI Wen, John/0000-0002-5123-5411; Lanari, Leonardo/0000-0002-8546-1783 NR 22 TC 24 Z9 24 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-6911 J9 SYST CONTROL LETT JI Syst. Control Lett. PD AUG PY 1992 VL 19 IS 2 BP 119 EP 129 DI 10.1016/0167-6911(92)90095-A PG 11 WC Automation & Control Systems; Operations Research & Management Science SC Automation & Control Systems; Operations Research & Management Science GA JH973 UT WOS:A1992JH97300004 ER PT J AU PARTRIDGE, H BAUSCHLICHER, CW AF PARTRIDGE, H BAUSCHLICHER, CW TI THE IMPORTANCE OF VALENCE P-FUNCTIONS IN THE BONDING OF NA2, K2, AND CU2 AND THEIR POSITIVE AND NEGATIVE-IONS SO THEORETICA CHIMICA ACTA LA English DT Article DE VALENCE P-FUNCTIONS; NA2; K2; CU2; BONDING ID CORE POLARIZATION POTENTIALS; GAUSSIAN-BASIS SETS; PHOTOELECTRON-SPECTRA; ABINITIO CALCULATIONS; ELECTRON-AFFINITIES; ALKALI DIMERS; ROW ATOMS AB The relative importance of the valence p functions for describing the bonding in the valence isoelectronic Na2, K2, and Cu2 molecules and their positive and negative ions is investigated. In absolute magnitude the contribution of the p functions to the dissociation energy follows the trend Cu > Na > K while by percentage of the dissociation energy the importance of the p functions follows the polarizabilities, i.e. K > Na > Cu. The bonding in K2, K2+, and K2-is analyzed to explain the observed trends. RP PARTRIDGE, H (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 19 TC 8 Z9 8 U1 1 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0040-5744 J9 THEOR CHIM ACTA JI Theor. Chim. Acta PD AUG PY 1992 VL 83 IS 3-4 BP 201 EP 208 DI 10.1007/BF01132829 PG 8 WC Chemistry, Physical SC Chemistry GA JH657 UT WOS:A1992JH65700004 ER PT J AU STONE, LS THOMPSON, P AF STONE, LS THOMPSON, P TI HUMAN SPEED PERCEPTION IS CONTRAST DEPENDENT SO VISION RESEARCH LA English DT Article DE MOTION PERCEPTION; SPEED DISCRIMINATION; DIRECTION DISCRIMINATION; CONTRAST; MOTION ENERGY; GRATINGS; PLAIDS ID MACAQUE STRIATE CORTEX; SPATIAL-FREQUENCY; PERCEIVED DIRECTION; ORIENTATION COLUMNS; TEMPORAL FREQUENCY; FUNCTIONAL-ANATOMY; OCULAR-DOMINANCE; HUMAN-VISION; VISUAL AREA; MOTION AB When two parallel gratings moving at the same speed are presented simultaneously, the lower-contrast grating appears slower. This misperception is evident across a wide range of contrasts (2.5-50%) and does not appear to saturate (e.g. a 50% contrast grating appears slower than a 70% contrast grating moving at the same speed). On average, a 70% contrast grating must be slowed by 35% to match a 10% contrast grating moving at 2-degrees/sec (N = 6). Furthermore, the effect is largely independent of the absolute contrast level and is a quasilinear function of log contrast ratio. A preliminary parametric study shows that, although spatial frequency has little effect, relative orientation is important. Finally, the misperception of relative speed appears lessened when the stimuli to be matched are presented sequentially. C1 NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035. UNIV YORK,DEPT PSYCHOL,YORK YO1 5DD,N YORKSHIRE,ENGLAND. RP STONE, LS (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035, USA. NR 62 TC 185 Z9 186 U1 2 U2 13 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0042-6989 J9 VISION RES JI Vision Res. PD AUG PY 1992 VL 32 IS 8 BP 1535 EP 1549 DI 10.1016/0042-6989(92)90209-2 PG 15 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA JD025 UT WOS:A1992JD02500016 PM 1455726 ER PT J AU HEEGER, DJ AF HEEGER, DJ TI NORMALIZATION OF CELL RESPONSES IN CAT STRIATE CORTEX SO VISUAL NEUROSCIENCE LA English DT Review DE STRIATE (PRIMARY VISUAL) CORTEX; SIMPLE CELLS; COMPLEX CELLS; LINEAR OPERATORS; ENERGY MECHANISMS; NORMALIZATION; DIVISIVE SUPPRESSION; GAIN CONTROL; RESPONSE SATURATION; ADAPTATION; NONSPECIFIC SUPPRESSION ID RECEPTIVE-FIELD PROPERTIES; VISUAL CORTICAL-NEURONS; CONTRAST GAIN-CONTROL; MOVING TEXTURED BACKGROUNDS; LATERAL GENICULATE-NUCLEUS; COMPLEX CELLS; ORIENTATION SELECTIVITY; SINGLE UNITS; DIRECTIONAL SELECTIVITY; TEMPORAL SUMMATION AB Simple cells in the striate cortex have been depicted as half-wave-rectified linear operators. Complex cells have been depicted as energy mechanisms, constructed from the squared sum of the outputs of quadrature pairs of linear operators. However, the linear/energy model falls short of a complete explanation of striate cell responses. In this paper, a modified version of the linear/energy model is presented in which striate cells mutually inhibit one another, effectively normalizing their responses with respect to stimulus contrast. This paper reviews experimental measurements of striate cell responses, and shows that the new model explains a significantly larger body of physiological data. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HEEGER, DJ (reprint author), STANFORD UNIV,DEPT PSYCHOL,BLDG 420,STANFORD,CA 94305, USA. NR 111 TC 1063 Z9 1068 U1 3 U2 31 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0952-5238 J9 VISUAL NEUROSCI JI Visual Neurosci. PD AUG PY 1992 VL 9 IS 2 BP 181 EP 197 PG 17 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA JD053 UT WOS:A1992JD05300008 PM 1504027 ER PT J AU SODUPE, M BAUSCHLICHER, CW AF SODUPE, M BAUSCHLICHER, CW TI A THEORETICAL-STUDY OF THE SPECTROSCOPY OF MGH2O+ AND MGCH3OH+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID LIGAND BINDING-ENERGIES; MOLECULAR CALCULATIONS; BASIS SETS; ROW ATOMS; SPECTRA AB The structures, binding energies, and vibrational frequencies have been determined for the ground and excited states of MgCH3OH+. The vibrational frequencies are also reported for the four lowest electronic states of MgH2O+ to supplement our previous vertical excitation energies. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 13 TC 58 Z9 59 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 JUL 31 PY 1992 VL 195 IS 5-6 BP 494 EP 499 DI 10.1016/0009-2614(92)85550-T PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JG998 UT WOS:A1992JG99800006 ER PT J AU SATORIUS, EH MULLIGAN, JJ AF SATORIUS, EH MULLIGAN, JJ TI MINIMUM ENTROPY DECONVOLUTION AND BLIND EQUALIZATION SO ELECTRONICS LETTERS LA English DT Article DE DIGITAL COMMUNICATIONS; EQUALIZATION; CONVOLUTION ID SYSTEMS AB Relationships between minimum entropy deconvolution, developed primarily for geophysics applications, and blind equalisation are pointed out. It is seen that a large class of existing blind equalisation algorithms are directly related to the scale-invariant cost functions used in minimum entropy deconvolution. Thus the extensive analyses of these cost functions can be directly applied to blind equalisation, including the important asymptotic results of Donoho. C1 USA,CECOM SIGNALS WARFARE DIRECTORATE,AMSEL RD SW TRS,VINT HILL FARMS STN,WARRENTON,VA 22186. RP SATORIUS, EH (reprint author), JET PROP LAB,MS 238-420,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 9 Z9 9 U1 0 U2 1 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD JUL 30 PY 1992 VL 28 IS 16 BP 1534 EP 1535 DI 10.1049/el:19920974 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA JJ037 UT WOS:A1992JJ03700037 ER PT J AU SURESH, A LIOU, MS AF SURESH, A LIOU, MS TI THE OSHER SCHEME FOR NONEQUILIBRIUM REACTING FLOWS SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE REACTING FLOW; OSHER SCHEME; RIEMANN SOLVER; ZND DETONATION ID HYPERBOLIC CONSERVATION-LAWS; REAL GASES; DIFFERENCE-SCHEMES; SHOCK-WAVES; FLUX; EQUATIONS AB An extension of the Osher upwind scheme to non-equilibrium reacting flows is presented, Owing to the presence of source terms, the Riemann problem is no longer self-similar and therefore its approximate solution becomes tedious. With simplicity in mind, a linearized approach which avoids an iterative solution is used to define the intermediate states and sonic points. The source terms are treated explicitly. Numerical computations are presented to demonstrate the feasibility, efficiency and accuracy of the proposed method. The test problems include a ZND (Zeldovich-Neumann-Doring) detonation problem for which spurious numerical solutions which propagate at mesh speed have been observed on coarse grids. With the present method, a change of limiter causes the solution to change from the physically correct CJ detonation solution to the spurious weak detonation solution. RP SURESH, A (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 19 TC 5 Z9 5 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD JUL 30 PY 1992 VL 15 IS 2 BP 219 EP 232 DI 10.1002/fld.1650150206 PG 14 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA JD880 UT WOS:A1992JD88000005 ER PT J AU FU, R DELGENIO, AD ROSSOW, WB LIU, WT AF FU, R DELGENIO, AD ROSSOW, WB LIU, WT TI CIRRUS-CLOUD THERMOSTAT FOR TROPICAL SEA-SURFACE TEMPERATURES TESTED USING SATELLITE DATA SO NATURE LA English DT Article ID VARIABILITY; PACIFIC AB RAMANATHAN and Collins1 have suggested cirrus clouds associated with tropical convection might act as a 'thermostat' to limit tropical sea surface temperatures (SSTs) to less than 305 K by shielding the ocean from sunlight. Here we use satellite radiance data to test this hypothesis. We find that changes in the properties of cirrus clouds do not seem to be related to changes in SSTs. During the 1987 El Nino event, large-scale perturbations to the radiative effects of cirrus clouds were controlled by changes in large-scale atmospheric circulation rather than directly by SSTs. If they are averaged over the entire tropical Pacific, increases in surface evaporative cooling are stronger than decreases in solar heating owing to cirrus cloud variations. Thus we conclude that there is no 'cirrus cloud thermostat' to tropical SSTs. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. NASA,JET PROPULS LAB,PASADENA,CA 91109. RP FU, R (reprint author), UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024, USA. RI Del Genio, Anthony/D-4663-2012; Fu, Rong/B-4922-2011; Rossow, William/F-3138-2015 OI Del Genio, Anthony/0000-0001-7450-1359; NR 8 TC 95 Z9 97 U1 0 U2 3 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 30 PY 1992 VL 358 IS 6385 BP 394 EP 397 DI 10.1038/358394a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JF853 UT WOS:A1992JF85300048 ER PT J AU LIU, HS AF LIU, HS TI FREQUENCY VARIATIONS OF THE EARTHS OBLIQUITY AND THE 100-KYR ICE-AGE CYCLES SO NATURE LA English DT Article ID ASTRONOMICAL THEORY; CLIMATIC RESPONSE; SHEET MODEL; CALIBRATION; HISTORY; MARS AB VARIATIONS in the Earth's orbital parameters modulate the seasonal distribution of solar radiation and thereby induce changes in the Earth's climate1. Periodicities in the geological climate record with cycles of 100, 41 and 23 kyr have been linked with changes in eccentricity, obliquity and precession of the equinoxes, respectively2,3. But although the eccentricity does vary with a 100-kyr period, the effect on the incoming solar radiation is rather weak relative to the signals from obliquity and precession variations. The 100-kyr signal in the climate record should therefore be of negligible intensity, yet it is observed instead to dominate the record. Internal, nonlinear processes within the climate system have been proposed to account for this fact4-14. In contrast, I show here that variations in the frequency of the obliquity cycle can give rise to strong 100-kyr forcing of climate. RP LIU, HS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. NR 25 TC 32 Z9 34 U1 0 U2 4 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 30 PY 1992 VL 358 IS 6385 BP 397 EP 399 DI 10.1038/358397a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JF853 UT WOS:A1992JF85300049 ER PT J AU HOLLAND, KN BRILL, RW CHANG, RKC SIBERT, JR FOURNIER, DA AF HOLLAND, KN BRILL, RW CHANG, RKC SIBERT, JR FOURNIER, DA TI PHYSIOLOGICAL AND BEHAVIORAL THERMOREGULATION IN BIGEYE TUNA (THUNNUS-OBESUS) SO NATURE LA English DT Article ID FISH; MOVEMENTS AB TUNA are unique among teleost fishes in being thermoconserving. Vascular counter-current heat exchangers maintain body temperatures above ambient water temperature, thereby improving locomotor muscle efficiency, especially at burst speeds and when pursuing prey below the thermocline1-6. Because tuna also occasionally swim rapidly in warm surface waters, it has been hypothesized that tuna thermoregulate to accommodate changing activity levels or ambient temperatures7. But previous field experiments have been unable to demonstrate definitively short-latency, mammalian-type physiological thermoregulation8,9. Here we show using telemetered data that free-ranging bigeye tuna (Thunnus obesus) can rapidly alter whole-body thermal conductivity by two orders of magnitude. The heat exchangers are disengaged to allow rapid warming as the tuna ascend from cold water into warmer surface waters, and are reactivated to conserve heat when they return into the depths. Combining physiological and behavioural thermoregulation expands the foraging space of bigeye tuna into otherwise prohibitively cold, deep water. C1 NATL MARINE FISHERIES SERV,HONOLULU LAB,HONOLULU,HI 96822. OTTER RES LTD,NANAIMO,BC,CANADA. RP HOLLAND, KN (reprint author), HAWAII INST MARINE BIOL,POB 1346,COCONUT ISL,KANEOHE,HI 96744, USA. NR 21 TC 137 Z9 146 U1 3 U2 34 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 30 PY 1992 VL 358 IS 6385 BP 410 EP 412 DI 10.1038/358410a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JF853 UT WOS:A1992JF85300054 PM 1641023 ER PT J AU ZETNER, PW LI, Y TRAJMAR, S AF ZETNER, PW LI, Y TRAJMAR, S TI A MEASUREMENT OF ELECTRON-IMPACT COHERENCE PARAMETERS BY SUPERELASTIC SCATTERING FROM LASER-EXCITED BA-138(...6S6P1P1) SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID PHOTON COINCIDENCE EXPERIMENTS; EXCITATION; SODIUM; ORIENTATION; ANGLES; ATOMS AB Superelastic scattering of electrons from laser-excited Ba-138(... 6s6p P-1(1)) is used to measure the electron impact coherence parameters for excitation of this state. In particular, the variation with scattering angle of the charge cloud asymmetry parameter, P1+, and the alignment angle parameter, gamma, have been determined at two incident electron energies. Comparison with recent theoretical results based on the unitarized distorted wave approximation has been made taking into account any possible distortion in the measurements due to the influence of a finite interaction volume. This comparison reveals good quantitative agreement for the gamma-parameter over the range of scattering angles studied. Differences between the observed and predicted P1+ parameters are small for near-forward scattering but become significant at the larger scattering angles studied. C1 JET PROP LAB,PASADENA,CA 91109. RP ZETNER, PW (reprint author), UNIV MANITOBA,DEPT PHYS,WINNIPEG R3T 2N2,MANITOBA,CANADA. NR 25 TC 25 Z9 25 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD JUL 28 PY 1992 VL 25 IS 14 BP 3187 EP 3199 DI 10.1088/0953-4075/25/14/013 PG 13 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA JG798 UT WOS:A1992JG79800013 ER PT J AU BISHOP, J ATREYA, SK ROMANI, PN SANDEL, BR HERBERT, F AF BISHOP, J ATREYA, SK ROMANI, PN SANDEL, BR HERBERT, F TI VOYAGER-2 ULTRAVIOLET SPECTROMETER SOLAR OCCULTATIONS AT NEPTUNE - CONSTRAINTS ON THE ABUNDANCE OF METHANE IN THE STRATOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INFRARED OBSERVATIONS; MOIST CONVECTION; THERMAL STRUCTURE; URANUS; ATMOSPHERE; PHOTOCHEMISTRY; TRITON; OBLATENESS; ENCOUNTER; DYNAMICS AB Voyager 2 ultraviolet spectrometer (UVS) solar occultation lightcurves at wavelengths 125-138 ran acquired during the Neptune encounter are compared with one-dimensional methane photochemical-transport models. Photoabsorption by methane (the photochemical parent) is expected to be the major source of opacity at these wavelengths, in which case the UVS lightcurves can be used to infer the strength of eddy mixing at altitudes above the methane photolysis peak and compatible CH4 mixing ratios in the lower stratosphere. For the p-T models adopted in this study, acceptable fits to the UVS lightcurves are obtained with eddy mixing coefficient values (K1/2) near the half-light altitudes (placed 550-600 km above the respective 1 bar levels) of 2-15 x 10(6) cm2 s-1 (ingress) and 4-35 X 10(6) cm2 s-1 (egress) and lower stratospheric (p > 1.0 mbar) methane mixing ratio values (f(T)(CH4)) of 5-100 x 10(-5) (ingress and egress). The ranges in f(T)(CH4) and K1/2 reflect uncertainties in the background. p-T structure and the application of different criteria for deciding what constitutes a ''good fit.'' For the nominal p-T models and a criterion based on replicating the spacing in altitude of the 125-138 nm UVS lightcurves, K1/2 values (near 0.2 mubar) of 10(7) cm2 s-1 (ingress) and 1-2 x 10(7) cm2 s-1 (egress) and f(T)(CH4) values of approximately 1 x 10(-4) (ingress and egress) are indicated, with the egress results being more uncertain. These results are insensitive to photochemical details of the models. C1 UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RI Romani, Paul/D-2729-2012 NR 37 TC 23 Z9 23 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUL 25 PY 1992 VL 97 IS E7 BP 11681 EP 11694 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU051 UT WOS:A1992KU05100004 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR AF BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR TI COMPARATIVE-STUDY OF THE DISSOCIATION-ENERGIES OF NI2 AND NI2+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID TRANSITION-METAL ATOMS; GAUSSIAN-BASIS SETS; ORBITALS; EXPANSIONS; CLUSTERS; 1ST-ROW; CI(SD) AB Computations at the internally contracted averaged coupled-pair-functional level of theory yield a dissociation energy (D0) for Ni2+ that is 0.17 eV larger than that of Ni2. This finding is consistent with the collision-induced dissociation experiments of Lian, Su, and Armentrout, but rules out the results from the resonant two-photon dissociation experiments of Lessen and Brucat, which predict that the D0 value of Ni2+ is about 1 eV larger than that of Ni2. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 26 TC 23 Z9 23 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUL 24 PY 1992 VL 195 IS 4 BP 360 EP 364 DI 10.1016/0009-2614(92)85617-J PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JH380 UT WOS:A1992JH38000014 ER PT J AU SIREGAR, E ROBERTS, DA GOLDSTEIN, ML AF SIREGAR, E ROBERTS, DA GOLDSTEIN, ML TI AN EVOLVING MHD VORTEX STREET MODEL FOR QUASI-PERIODIC SOLAR-WIND FLUCTUATIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OUTER HELIOSPHERE; PLASMA-FLOW AB We use magnetohydrodynamic (MHD) simulation to provide a dynamical basis for the "vortex street" model of the quasi-periodic meridional flow observed by Voyager 2 in the outer heliosphere. Various observations suggest that near the current sheet at solar minimum one can expect to find a vorticity distribution of two opposite shear layers with an antisymmetric staggered vorticity pattern due to structured high-speed wind surrounding low-speed equatorial flow. We show that this flow pattern leads to the formation of a highly stable vortex street through the nonlinear interaction of the two shear layers. Spatial profiles of various simulated parameters (velocity, density, meridional flow angle and the location of magnetic sector boundaries) and their relative locations in the quasi-steady vortex street are generally in good agreement with the observations. A strong, flow-aligned magnetic field, such as would occur in the inner heliosphere, inhibits the development of the street which would then be masked by the background interplanetary turbulence. The flow produced by the street induces a (relatively small) transport of plasma and magnetic flux as a result of the meridional flow away from the ecliptic region. RP SIREGAR, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012; Goldstein, Melvyn/B-1724-2008 NR 9 TC 14 Z9 14 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 24 PY 1992 VL 19 IS 14 BP 1427 EP 1430 DI 10.1029/92GL01616 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JG914 UT WOS:A1992JG91400003 ER PT J AU OWEN, CJ SLAVIN, JA AF OWEN, CJ SLAVIN, JA TI VISCOUSLY DRIVEN PLASMA FLOWS IN THE DEEP GEOMAGNETIC TAIL SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LATITUDE BOUNDARY-LAYER; DISTANT MAGNETOTAIL; MAGNETOSPHERE; ISEE-3; SHEET AB We present an analysis, based on the principles of stress balance in a 1-dimensional current sheet, which considers the problem of closed magnetic flux transport into the deep tail by a "viscous"-like interaction between the solar wind and the magnetosphere. We illustrate our analysis with an example of ISEE-3 data showing strong tailward plasma sheet flows on apparently closed field lines in the deep tail. Apart from narrow regions adjacent to the magnetopause, these flows are not driven by the scattering of magnetosheath plasma into the magnetosphere. We estimate the fraction of the magnetosheath momentum flux needed to be anomalously transferred into the plasma sheet to drive the flows. In our example this is approximately 6%. No previously suggested mechanism (eg., the Kelvin-Helmholtz Instability) has been shown capable of providing anomalous momentum transport of this magnitude. Our current understanding of the "viscous" interaction between the solar wind and magnetosphere is thus insufficient to explain these observations. RP OWEN, CJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. RI Owen, Christopher/C-2999-2008; Slavin, James/H-3170-2012 OI Owen, Christopher/0000-0002-5982-4667; Slavin, James/0000-0002-9206-724X NR 16 TC 16 Z9 16 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 24 PY 1992 VL 19 IS 14 BP 1443 EP 1446 DI 10.1029/92GL01280 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JG914 UT WOS:A1992JG91400007 ER PT J AU LEHMANN, P KAROLY, DJ NEWMAN, PA CLARKSON, TS MATTHEWS, WA AF LEHMANN, P KAROLY, DJ NEWMAN, PA CLARKSON, TS MATTHEWS, WA TI LONG-TERM WINTER TOTAL OZONE CHANGES AT MACQUARIE-ISLAND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HEMISPHERE AB Measurements of total ozone at Macquarie Island (55-degrees-S, 159-degrees-E) reveal statistically significant reductions of approximately twelve percent during July to September when comparing the mean levels for 1987-90 with those in the seventies. A back-correction of 1963-79 Macquarie Island monthly mean ozone data is described which enabled this comparison. C1 NATL INST WATER & ATMOSPHER RES LTD,WELLINGTON,NEW ZEALAND. MONASH UNIV,CTR DYNAM METEOROL,CLAYTON,VIC 3168,AUSTRALIA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP LEHMANN, P (reprint author), BUR METEOROL,GPO BOX 1289K,MELBOURNE 3001,AUSTRALIA. RI Karoly, David/C-8262-2011; Newman, Paul/D-6208-2012 OI Karoly, David/0000-0002-8671-2994; Newman, Paul/0000-0003-1139-2508 NR 9 TC 11 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 24 PY 1992 VL 19 IS 14 BP 1459 EP 1462 DI 10.1029/92GL01444 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JG914 UT WOS:A1992JG91400011 ER PT J AU LEHMANN, P KAROLY, DJ NEWMAN, PA CLARKSON, TS MATTHEWS, WA AF LEHMANN, P KAROLY, DJ NEWMAN, PA CLARKSON, TS MATTHEWS, WA TI AN INVESTIGATION INTO THE CAUSES OF STRATOSPHERIC OZONE LOSS IN THE SOUTHERN AUSTRALASIAN REGION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TRENDS; HEMISPHERES; CYCLE AB Measurements of total ozone at Macquarie Island (55-degrees-S, 159-degrees-E) reveal statistically significant reductions of approximately twelve percent during July to September when comparing the mean levels for 1987-90 with those in the seventies. In order to investigate the possibility that these ozone changes may not be a result of dynamic variability of the stratosphere, a simple linear model of ozone was created from statistical analysis of tropopause height and isentropic transient eddy heat flux, which were assumed representative of the dominant dynamic influences. Comparison of measured ana modelled ozone indicates that the recent downward trend in ozone at Macquarie Island is not related to stratospheric dynamic variability and therefore suggests another mechanism, possibly changes in photochemical destruction of ozone. C1 NATL INST WATER & ATMOSPHER RES LTD,WELLINGTON,NEW ZEALAND. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MONASH UNIV,CTR DYNAM METEOROL,CLAYTON,VIC 3168,AUSTRALIA. RP LEHMANN, P (reprint author), BUR METEOROL,GPO BOX 1289K,MELBOURNE 3001,AUSTRALIA. RI Karoly, David/C-8262-2011; Newman, Paul/D-6208-2012 OI Karoly, David/0000-0002-8671-2994; Newman, Paul/0000-0003-1139-2508 NR 18 TC 10 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 24 PY 1992 VL 19 IS 14 BP 1463 EP 1466 DI 10.1029/92GL01443 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JG914 UT WOS:A1992JG91400012 ER PT J AU VIGUE, Y LICHTEN, SM BLEWITT, G HEFLIN, MB MALLA, RP AF VIGUE, Y LICHTEN, SM BLEWITT, G HEFLIN, MB MALLA, RP TI PRECISE DETERMINATION OF EARTHS CENTER OF MASS USING MEASUREMENTS FROM THE GLOBAL POSITIONING SYSTEM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GPS ORBIT AB Global Positioning System (GPS) data from a worldwide geodetic experiment were collected during a 3 week period early in 1991. We estimated geocentric station coordinates using the GPS data, thus defining a dynamically determined reference frame origin which should coincide with the Earth center of mass, or geocenter. The 3-week GPS average geocenter estimates agree to 7-13 cm with geocenter estimates determined from satellite laser ranging, a well-established technique. The RMS of daily GPS geocenter estimates were 4 cm for x and y, and 30 cm for z. RP VIGUE, Y (reprint author), JET PROP LAB,MAIL STOP 238-600,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 18 Z9 18 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 24 PY 1992 VL 19 IS 14 BP 1487 EP 1490 DI 10.1029/92GL01575 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JG914 UT WOS:A1992JG91400018 ER PT J AU LARSON, KM WEBB, FH AF LARSON, KM WEBB, FH TI DEFORMATION IN THE SANTA-BARBARA CHANNEL FROM GPS MEASUREMENTS 1987-1991 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GLOBAL POSITIONING SYSTEM; WESTERN TRANSVERSE RANGES; CRUSTAL DEFORMATION; CALIFORNIA; FAULT AB Geodesy is one of the few techniques that can be used to estimate strain rates across the submerged structures in the Santa Barbara Channel. By resolving relative surface velocities, the Global Positioning System (GPS) can be used to infer crustal deformation rates independent of geologic models. GPS measurements from the period 1987-1991 have been used to derive velocities for a 8 station network bounding the channel. These estimates are based on 10 GPS experiments each of several days in length over this 4.5 year period. Precision of individual determinations of intersite vectors range from 3 to 7 mm for the horizontal components and average 20 mm in the vertical. The GPS data indicate high rates of shortening in the eastern channel (6+/-1 mm/yr at N16+/-3E) and low rates of deformation in the western channel. Comparisons with previous geodetic studies suggest that deformation in the region has not been uniform over the last 100 years. C1 JET PROP LAB,PASADENA,CA 91109. RP LARSON, KM (reprint author), UNIV COLORADO,CAMPUS BOX 429,BOULDER,CO 80309, USA. NR 19 TC 16 Z9 16 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 24 PY 1992 VL 19 IS 14 BP 1491 EP 1494 DI 10.1029/92GL01485 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JG914 UT WOS:A1992JG91400019 ER PT J AU HUDSON, RL MOORE, MH AF HUDSON, RL MOORE, MH TI A FAR-IR STUDY OF IRRADIATED AMORPHOUS ICE - AN UNREPORTED OSCILLATION BETWEEN AMORPHOUS AND CRYSTALLINE PHASES SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID DIFFRACTION PATTERN; RADIATION-CHEMISTRY; SOLID WATER AB Far-IR spectra have been recorded for amorphous H2O ice irradiated at 13-125 K with 0.7-MeV protons. Little or no changes were seen in the spectra of ices irradiated above approximately 27 K. However, at lower temperatures, most prominently at 13 K, IR spectra showed that ice samples oscillated between a highly amorphous and a highly crystalline form with increasing radiation dose. A mechanism for the oscillation is proposed involving free radical storage. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTROCHEM BRANCH,GREENBELT,MD 20771. RP HUDSON, RL (reprint author), ECKERD COLL,DEPT CHEM,ST PETERSBURG,FL 33733, USA. RI Hudson, Reggie/E-2335-2012 NR 55 TC 25 Z9 25 U1 1 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUL 23 PY 1992 VL 96 IS 15 BP 6500 EP 6504 DI 10.1021/j100194a072 PG 5 WC Chemistry, Physical SC Chemistry GA JF326 UT WOS:A1992JF32600072 ER PT J AU LINDSEY, C JEFFERIES, JT CLARK, TA HARRISON, RA CARTER, MK WATT, G BECKLIN, EE ROELLIG, TL BRAUN, DC NAYLOR, DA TOMPKINS, GJ AF LINDSEY, C JEFFERIES, JT CLARK, TA HARRISON, RA CARTER, MK WATT, G BECKLIN, EE ROELLIG, TL BRAUN, DC NAYLOR, DA TOMPKINS, GJ TI EXTREME-INFRARED BRIGHTNESS PROFILE OF THE SOLAR CHROMOSPHERE OBTAINED DURING THE TOTAL ECLIPSE OF 1991 SO NATURE LA English DT Article ID LIMB AB THE solar chromosphere is a thin layer of gas that is several thousand degrees hotter than the underlying photosphere, and responsible for most of the Sun's ultraviolet emission. The mechanism by which it is heated to temperatures exceeding 10,000 K is not understood. Millimetre and submillimetre radiometry can be used to obtain the chromospheric temperature profile, but the diffraction-limited resolution for the largest telescopes is at best 17 arcsec, or approximately 12,500 km at the Sun's distance. This is greater than the thickness of the quiet chromosphere itself. The total eclipse of July 1991, which passed over the Mauna Kea Observatory in Hawaii, provided a rare opportunity to make limb occultation observations with a large submillimetre-wavelength telescope, the 15-m James Clerk Maxwell Telescope, and in this way we obtained a temperature profile in 1.3-mm radiation with approximately 300 km resolution at the Sun. Our observations indicate that spicules (magnetically entrained funnels of gas) reach a temperature of 8,000 K at 3,000-4,000 km above the photosphere, a temperature lower than those of many spicule models. C1 NATL SOLAR OBSERV,NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. UNIV CALGARY,DEPT PHYS & ASTRON,CALGARY T2N 1N4,ALBERTA,CANADA. RUTHERFORD APPLETON LAB,DIV ASTROPHYS,DIDCOT OX11 0QX,OXON,ENGLAND. JOINT ASTRON CTR,JAMES CLERK MAXWELL TELESCOPE,HILO,HI 96720. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. NASA,AMES RES CTR,ASTROPHYS BRANCH,MOFFETT FIELD,CA 94035. UNIV LETHBRIDGE,DEPT PHYS,LETHBRIDGE T1K 3M4,ALBERTA,CANADA. RP LINDSEY, C (reprint author), UNIV HAWAII,INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. OI Watt, Graeme/0000-0001-7640-2741 NR 9 TC 9 Z9 9 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 23 PY 1992 VL 358 IS 6384 BP 308 EP 310 DI 10.1038/358308a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JE684 UT WOS:A1992JE68400056 ER PT J AU KORB, CL GENTRY, BM WENG, CY AF KORB, CL GENTRY, BM WENG, CY TI EDGE TECHNIQUE - THEORY AND APPLICATION TO THE LIDAR MEASUREMENT OF ATMOSPHERIC WIND SO APPLIED OPTICS LA English DT Article ID DOPPLER LIDAR; AIRBORNE; LASERS AB The edge technique is a new and powerful method for measuring small frequency shifts. With the edge technique a laser is located on the steep slope of a high-resolution spectral filter, which produces large changes in transmission for small frequency shifts. A differential technique renders the frequency shift measurement insensitive to both laser and filter frequency jitter and drift. The measurement is shown to be insensitive to the laser width and shape for widths that are less than the half-width of the edge filter. The theory of the measurement is given with application to the lidar measurement of wind. The edge technique can be used to measure wind with a lidar by using either the aerosol or molecular backscattered signal. Examples of both measurements are presented. Simulations for a ground-based lidar at 1.06-mu-m using reasonable instrumental parameters are used to show an accuracy for the vector components of the wind that is better than 0.5 m/s from the ground to an altitude of 20 km for a 100-m vertical resolution and a 100-shot average. For a 20-m vertical resolution and a 10-shot average, simulations show an accuracy of better than 0.2 m/s in the first 2 km and better than 0.5 m/s to 5 km. C1 SCI SYST & APPLICAT INC,SEABROOK,MD 20706. RP KORB, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 917,GREENBELT,MD 20771, USA. NR 33 TC 103 Z9 141 U1 3 U2 17 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1992 VL 31 IS 21 BP 4202 EP 4213 PG 12 WC Optics SC Optics GA JE407 UT WOS:A1992JE40700020 PM 20725404 ER PT J AU TRATT, DM AF TRATT, DM TI OPTIMIZING COHERENT LIDAR PERFORMANCE WITH GRADED-REFLECTANCE LASER RESONATOR OPTICS SO APPLIED OPTICS LA English DT Article DE LIDAR; GRADED OPTICS ID GAUSSIAN REFLECTIVITY MIRRORS; UNSTABLE RESONATORS; COATINGS; MODE AB We demonstrate how the design of graded-reflectance output coupler unstable laser cavities may be tailored to significantly enhance the overall power transmission efficiency of a given laser system relative to that of a conventional diffractively coupled unstable resonator. The importance of these findings in coherent lidar applications is explained with particular emphasis on projected space-based systems. RP TRATT, DM (reprint author), JET PROP LAB,MAIL STOP 169-214,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Tratt, David/A-7884-2009 OI Tratt, David/0000-0002-3942-6848 NR 19 TC 6 Z9 6 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1992 VL 31 IS 21 BP 4233 EP 4239 PG 7 WC Optics SC Optics GA JE407 UT WOS:A1992JE40700023 PM 20725407 ER PT J AU LUO, XC SCHRAMM, DN AF LUO, XC SCHRAMM, DN TI THICK STRINGS, THE LIQUID-CRYSTAL BLUE PHASE, AND COSMOLOGICAL LARGE-SCALE STRUCTURE SO ASTROPHYSICAL JOURNAL LA English DT Article DE HEADINGS, COSMOLOGY, THEORY; GALAXIES, CLUSTERING ID UNIVERSE; EVOLUTION; GALAXIES AB A phenomenological model based on the liquid crystal blue phase is proposed as a model for a late-time cosmological phase transition. Topological defects, in particular thick strings and/or domain walls, are presented as seeds for structure formation. It is shown that the observed large-scale structure, including quasiperiodic wall structure, can be well fitted in the model without violating the microwave background isotropy bound or the limits from induced gravitational waves and the millisecond pulsar timing. Furthermore, such late-time transitions can produce objects such as quasars at high redshifts (z greater than or similar to 5). The model appears to work with either cold or hot dark matter. C1 NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP LUO, XC (reprint author), UNIV CHICAGO,5640 S ELLIS AVE,CHICAGO,IL 60637, USA. NR 32 TC 2 Z9 2 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1992 VL 394 IS 1 BP 12 EP 18 DI 10.1086/171554 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD343 UT WOS:A1992JD34300003 ER PT J AU ELITZUR, M HOLLENBACH, DJ MCKEE, CF AF ELITZUR, M HOLLENBACH, DJ MCKEE, CF TI PLANAR H2O MASERS IN STAR-FORMING REGIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MASERS; STARS, FORMATION ID SUBMILLIMETER WATER MASER; ASTROPHYSICAL MASERS; ASTRONOMICAL MASERS; RADIATIVE-TRANSFER AB The planar geometry of shocked material is the key property in enabling the high brightness temperatures of H2O masers in star-forming regions. We solve for the brightness temperature, the beaming angle, and the maser spot size for thin, saturated planar masers under the assumption that the velocity change across the maser due to ordered motions is small compared with the thermal or microturbulent line width. For a given set of physical parameters, the brightness temperature is essentially fully determined by the length of the velocity-coherent region in the shocked plane along the line of sight. The geometry in the transverse direction in the plane is largely irrelevant; a saturated planar maser can generally be modeled as a disk, and a disk maser observed in the plane appears as bright as an equivalent filamentary maser whose length equals the disk diameter. Of the two independent dimensions perpendicular to the filament axis, one is equal to the disk thickness and the other is somewhat smaller than the size of the disk's unsaturated core. In astrophysical shocks, we show that the last two dimensions are approximately equal, so that the equivalent filament is roughly cylindrical. The ratio of the equivalent filament length to its width, or the effective aspect ratio, is determined by the disk diameter ard the pumping scheme. We find effective aspect ratios (approximately 5-50) that are in agreement with values previously inferred from observed brightness temperatures. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV CALIF BERKELEY, DEPT PHYS, BERKELEY, CA 94720 USA. UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. RP UNIV KENTUCKY, DEPT PHYS & ASTRON, LEXINGTON, KY 40506 USA. NR 25 TC 55 Z9 55 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 JUL 20 PY 1992 VL 394 IS 1 BP 221 EP 227 DI 10.1086/171574 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD343 UT WOS:A1992JD34300023 ER PT J AU SAHAI, R WANNIER, PG AF SAHAI, R WANNIER, PG TI SO AND SO2 IN MASS-LOSS ENVELOPES OF RED GIANTS - PROBES OF NONEQUILIBRIUM CIRCUMSTELLAR CHEMISTRY AND MASS-LOSS RATES SO ASTROPHYSICAL JOURNAL LA English DT Article DE MOLECULAR PROCESSES; RADIO LINES, MOLECULAR, CIRCUMSTELLAR; STARS, ABUNDANCES; STARS, GIANT; STARS, MASS LOSS ID IRC + 10216; COOL CARBON STARS; MOLECULAR ABUNDANCES; EVOLVED STARS; BEARING MOLECULES; OH/IR STARS; EMISSION; OXYGEN; IRAS; OH AB We have made a search for SO in the mass-loss envelopes of 24 mostly oxygen-rich red giants, using the 8(8)-7(7)(344.3 GHz), 6(5)-5(4) (219.9 GHz), 4(3)-3(2) (138.2 GHz), and 3(2)-2(1) (99.3 GHz) transitions. One or more of these transitions were detected toward 14 envelopes, including those of the supergiants VY CMa and IRC + 10420. The SO envelope of IK Tau was measurably extended, and that of IRC + 10420 marginally so, allowing us to determine the envelope sizes directly. The SiO (v = 0) J = 8-7, J = 5-4, and J = 3-2 lines at 347.3, 217.1, and 130.3 GHz were detected simultaneously with the 344.3, 219.9, and 138.2 GHz SO lines, respectively. From our SO data, as well as from SO2 data published elsewhere (for a few sources), we derive the circumstellar SO and SO2 abundances and compare them with theoretical predictions. We find that the photospheric abundances of SO and SO2 are insignificant, and that SO and SO2 must be produced in the circumstellar envelopes. However, the (average) SO abundances are larger than even the peak values predicted by nonequilibrium circumstellar chemistry models. The large SO abundances imply that S is not heavily depleted into grains in these envelopes, and further suggest that (i) the stellar mass-loss rates in these objects are substantially larger than accepted values, (ii) the circumstellar H/H-2 abundance ratio is quite small, and (iii) the reaction of O and SH dominates over the reaction of S and OH in the production of SO. In the peculiar bipolar nebula OH 231.8 + 4.2, the combined SO and SO2 abundance exceeds the cosmic S abundance, if the mass-loss rate in this object is smaller than or equal to 10(-4) M . yr-1. In IK Tau the data can only be fitted with models in which the SO is distributed in a hollow shell, as predicted by the nonequilibrium chemistry models. In another three, which have no measurable OH, the discovery of SO is difficult to explain by such models. C1 CHALMERS UNIV TECHNOL,S-41296 GOTHENBURG,SWEDEN. JET PROP LAB,PASADENA,CA 91109. RP SAHAI, R (reprint author), UNIV GOTHENBURG,DEPT ASTRON & ASTROPHYS,S-41296 GOTHENBURG,SWEDEN. NR 57 TC 26 Z9 26 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1992 VL 394 IS 1 BP 320 EP 339 DI 10.1086/171585 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD343 UT WOS:A1992JD34300034 PM 11540051 ER PT J AU REINER, MJ STONE, RG FAINBERG, J AF REINER, MJ STONE, RG FAINBERG, J TI DETECTION OF FUNDAMENTAL AND HARMONIC TYPE-III RADIO-EMISSION AND THE ASSOCIATED LANGMUIR-WAVES AT THE SOURCE REGION SO ASTROPHYSICAL JOURNAL LA English DT Article DE ARTIFICIAL SATELLITES, SPACE PROBES; INTERPLANETARY MEDIUM; RADIO CONTINUUM, SOLAR SYSTEM ID INTERPLANETARY SPACE; PLASMA FREQUENCY; BURSTS; ELECTRONS; PROPAGATION AB Type III radio emission generated in the vicinity of the Ulysses spacecraft has been detected at both the fundamental and harmonic of the local plasma frequency. These observations represent the first clear evidence of locally generated type III radio emission. This local emission shows no evidence of frequency drift, exhibits a relatively short rise time, is less intense than the observed remotely generated radio emission, and is temporally correlated with observed in situ Langmuir waves. The observations were made with the unified radio astronomy and plasma wave (URAP) experiment on the Ulysses spacecraft between 1990 November 4 and 1991 April 30, as it traveled from 1 to 3 AU from the Sun. During this time period many thousands of bursts were observed. However, only three examples of local emission and associated Langmuir waves were identified. This supports previous suggestions that type III radio emission is generated in localized regions of the interplanetary medium, rather than uniformly along the extent of the electron exciter beam. C1 HUGHES STX,LANHAM,MD. RP REINER, MJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 690-2,GREENBELT,MD 20771, USA. NR 36 TC 54 Z9 54 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1992 VL 394 IS 1 BP 340 EP 350 DI 10.1086/171586 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD343 UT WOS:A1992JD34300035 ER PT J AU PRYOR, WR AJELLO, JM BARTH, CA HORD, CW STEWART, AIF SIMMONS, KE MCCLINTOCK, WE SANDEL, BR SHEMANSKY, DE AF PRYOR, WR AJELLO, JM BARTH, CA HORD, CW STEWART, AIF SIMMONS, KE MCCLINTOCK, WE SANDEL, BR SHEMANSKY, DE TI THE GALILEO AND PIONEER-VENUS ULTRAVIOLET SPECTROMETER EXPERIMENTS - SOLAR LYMAN-ALPHA LATITUDE VARIATION AT SOLAR MAXIMUM FROM INTERPLANETARY LYMAN-ALPHA OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, ACTIVITY; SUN, UV RADIATION ID WIND; FLUX; MARINER-10; VARIABILITY; MINIMUM AB The Galileo ultraviolet spectrometer and Pioneer Venus Orbiter ultraviolet spectrometer (PVOUVS) experiments performed nearly simultaneous observations of the interplanetary Lyman-alpha-emissions (IP Lyman-alpha) at solar maximum in 1990. The Galileo ultraviolet spectrometer experiment consists of an ultraviolet spectrometer (UVS) and an extreme-ultraviolet spectrometer (EUVS) both of which began acquiring IP Lyman-alpha data late in 1989. The PVOUVS has been in operation since 1978. A comparison is made of the latitude variation of the IP Lyman-alpha signal in 1986 at solar minimum from Pioneer Venus (PV) and in 1990 at solar maximum from Galileo. The Galileo EUVS shows a large enhancement of the IP Lyman-alpha emission has occurred over the intervening 4 years near the solar equator. An IP Lyman-alpha model has been developed which considers the latitude variation of the solar Lyman-alpha flux. The model is based upon the fraction of the solar disk occupied by plage regions. Low-latitude plage regions are the source of the enhanced Lyman-alpha flux near the solar equator. The model fit to the data shows a 25% decrease of the full disk solar Lyman-alpha flux from solar equator to solar pole in 1990. At the extremes of the solar cycle the dominant causes of IP Lyman-alpha asymmetries have now been determined from UVS observations spanning the region ecliptic pole to equator. The latitudinal variations in the solar Lyman-alpha radiation field are the explanation at solar maximum and the solar wind field is the basis at solar minimum. A detailed study of the Galileo IP Lyman-alpha observations on day-of-year (DOY) 190, 193, 197, and 200 in 1990 reveals large daily-variations occur in response to the 27 day solar variation. Analysis of these data shows a maximum variation of 20% can be expected in the IP Lyman-alpha upwind intensity over this 27 day period. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. JET PROP LAB,PASADENA,CA 91109. UNIV SO CALIF,DEPT AEROSP ENGN,LOS ANGELES,CA 90089. RP PRYOR, WR (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309, USA. NR 23 TC 55 Z9 55 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1992 VL 394 IS 1 BP 363 EP 377 DI 10.1086/171589 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD343 UT WOS:A1992JD34300038 ER PT J AU CARLSON, BE MA, QC LACIS, AA AF CARLSON, BE MA, QC LACIS, AA TI ON THE INCLUSION OF THE HYDROGEN DIMER IN THE ANALYSIS OF VOYAGER IRIS SPECTRA SO ASTROPHYSICAL JOURNAL LA English DT Article DE PLANETS AND SATELLITES, INDIVIDUAL, JUPITER ID FAR-INFRARED SPECTRA; ABSORPTION-SPECTRA; JUPITER; ATMOSPHERES; PLANETS; SATURN; PAIRS AB Empirical formulas are fitted to existing theoretical absorption spectra of H-2-H-2 pairs in the far-infrared allowing-us to include dimer absorption, parameterized with the height dependence of the para-hydrogen profile, in our calculations. Comparison between synthetic and Voyager IRIS spectra shows that once the dimer absorption is included it is now possible to reproduce the hydrogen portion of the IRIS spectrum to within the precision of the measurements. C1 COLUMBIA UNIV,CTR STUDY GLOBAL HABITABIL,NEW YORK,NY 10025. RP CARLSON, BE (reprint author), GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Lacis, Andrew/D-4658-2012; Carlson, Barbara/D-8319-2012 NR 13 TC 0 Z9 0 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1992 VL 394 IS 1 BP L29 EP L32 DI 10.1086/186465 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD346 UT WOS:A1992JD34600008 ER PT J AU DRISCOLL, KT BLAKESLEE, RJ BAGINSKI, ME AF DRISCOLL, KT BLAKESLEE, RJ BAGINSKI, ME TI A MODELING STUDY OF THE TIME-AVERAGED ELECTRIC CURRENTS IN THE VICINITY OF ISOLATED THUNDERSTORMS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID FIELDS AB A thorough examination of the results of a time-dependent computer model of a dipole thunderstorm revealed that there are numerous similarities between the time-averaged electrical properties and the steady state properties of an active thunderstorm. Thus, the electrical behavior of the atmosphere in the vicinity of a thunderstorm be can be determined with a formulation similar to what was first described by Holzer and Saxon in 1952. From the Maxwell continuity equation of electric current, a simple analytical equation was derived that expresses a thunderstorm's average current contribution to the global electric circuit in terms of the generator current within the thundercloud, the intracloud lightning current, the cloud-to-ground lightning current, the altitudes of the charge centers, and the conductivity profile of the atmosphere. This equation was found to be nearly as accurate as the more computationally expensive numerical model, even when it is applied to a thunderstorm with a reduced conductivity thundercloud, a time-varying generator current, a varying flash rate, and a changing lightning mix. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. RP DRISCOLL, KT (reprint author), AUBURN UNIV, DEPT ELECT ENGN, AUBURN, AL 36849 USA. NR 25 TC 33 Z9 33 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 JUL 20 PY 1992 VL 97 IS D11 BP 11535 EP 11551 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JG656 UT WOS:A1992JG65600005 ER PT J AU WILLIAMS, EJ SANDHOLM, ST BRADSHAW, JD SCHENDEL, JS LANGFORD, AO QUINN, PK LEBEL, PJ VAY, SA ROBERTS, PD NORTON, RB WATKINS, BA BUHR, MP PARRISH, DD CALVERT, JG FEHSENFELD, FC AF WILLIAMS, EJ SANDHOLM, ST BRADSHAW, JD SCHENDEL, JS LANGFORD, AO QUINN, PK LEBEL, PJ VAY, SA ROBERTS, PD NORTON, RB WATKINS, BA BUHR, MP PARRISH, DD CALVERT, JG FEHSENFELD, FC TI AN INTERCOMPARISON OF 5 AMMONIA MEASUREMENT TECHNIQUES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC AMMONIA; NITRIC-ACID; UNITED-STATES; AMBIENT AIR; SYSTEM AB An intercomparison has been conducted among five instruments which measure gas phase ammonia at low concentration in the atmosphere: (1) a photofragmentation/laser-induced fluorescence (PF/LIF) instrument; (2) a molybdenum oxide annular denuder sampling/chemiluminescence detection (MOADS) technique; (3) a tungsten oxide denuder sampling/chemiluminescence detection (DARE) system; (4) a citric acid coated denuder sampling/ion chromatographic analysis (CAD/IC) method; and (5) an oxalic acid coated filter pack sampling/colorimetric analysis (FP/COL) method. Mixtures of ammonia in air at flow rates of 1800 (STP) L/min and concentrations from 0.1 to 14 parts per billion by volume (ppbv) with the addition of possible interferants (CH3NH2, CH3CN, NO, NO2, O3, and H2O) were provided for simultaneous tests. In addition, the five instruments made simultaneous ambient air measurements both from a common manifold and from their separate inlets located at a common height above the ground. Several conclusions were reached: (1) No artifacts or interferences were conclusively established for any of the techniques, although CH3NH2 may interfere in the MOADS system. (2) Measurements from the PF/LIF and the CAD/IC methods agreed well with the prepared mixtures over the full range of ammonia. concentrations. The high specificity and time resolution (1 min) of the PF/LIF results allowed data from this technique to be used as a basis set for comparisons. (-3) For fog-free conditions, ambient measurements from all of the instruments generally agreed to within a factor of 2 for ammonia levels above 0.5 ppbv. The CAD/IC and PF/LIF instruments agreed to within 15% on average for all ambient data. (4) The slope from linear regression analysis of separate inlet ambient air measurements indicated that the DARE data agreed with those from the PF/LIF system to within 7%. The linear regression line intercept was 216 parts per trillion by volume (pptv), which may indicate a positive interference in the DARE data, but the DARE data were closer to the PF/LIF data (50 - 100 pptv higher) at the lowest ambient ammonia levels. (5) The FP/COL method measured about 66% of the ammonia as determined by the PF/LIF technique and measured even lower fractional levels in the prepared samples. These low values indicate a loss of ammonia, possibly on the Teflon prefilter, under the conditions of this study (cold temperatures and generally low relative humidity). (6)The MOADS ambient air data were about 64% of the ammonia that was observed by the PF/LIF method for levels greater than about 1 ppbv, and below this level it overestimated ammonia. Problems with the MOADS calibrations and inlets may have been responsible. (7) Ambient air data from the one period of fog formation indicated that ambient ammonia was primarily partitioned into the condensed phase, leaving the interstitial air greatly depleted. Volatilization of absorbed ammonia from water droplets entrained in the sampled air appeared to influence the MOADS system. This did not appear to affect the FP/COL, CAD/IC, or PF/LIF results as a result of fast sample flows and/or operation at ambient temperatures. C1 UNIV COLORADO, NOAA, COOPERAT INST RES ENVIRONM SCI, BOULDER, CO 80309 USA. GEORGIA INST TECHNOL, SCH EARTH & ATMOSPHER SCI, ATLANTA, GA 30332 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. HAMPTON UNIV, HAMPTON, VA USA. RP WILLIAMS, EJ (reprint author), NOAA, AERON LAB, 325 BROADWAY, BOULDER, CO 80303 USA. RI Langford, Andrew/D-2323-2009; Williams, Eric/F-1184-2010; Parrish, David/E-8957-2010; Fehsenfeld, Frederick/I-4876-2013; Quinn, Patricia/R-1493-2016 OI Langford, Andrew/0000-0002-2932-7061; Parrish, David/0000-0001-6312-2724; Quinn, Patricia/0000-0003-0337-4895 NR 29 TC 42 Z9 42 U1 4 U2 18 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 JUL 20 PY 1992 VL 97 IS D11 BP 11591 EP 11611 DI 10.1029/92JD00721 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JG656 UT WOS:A1992JG65600010 ER PT J AU WATERS, JF SUKENIK, CN KENNEDY, VO LIVNEH, M YOUNGS, WJ SUTTER, JK MEADOR, MAB BURKE, LA AHN, MK AF WATERS, JF SUKENIK, CN KENNEDY, VO LIVNEH, M YOUNGS, WJ SUTTER, JK MEADOR, MAB BURKE, LA AHN, MK TI LOWER TEMPERATURE CURING THERMOSET POLYIMIDES UTILIZING A SUBSTITUTED NORBORNENE ENDCAP SO MACROMOLECULES LA English DT Article AB Methoxycarbonyl bridgehead substituted nadic diacid monomethyl eater, when used as an endcapping monomer, lowered the cure temperature of thermoset PMR polyimides without seriously affecting other desirable properties, such as glass transition temperature and thermal oxidative stability. The C-13 CP/MAS NMR of model compounds was used to follow the cure of resin systems using both the unmodified nadic endcap and the methoxycarbonyl-substituted endcap. Rheological analysis and differential scanning calorimetry (DSC) also provided evidence for the lower curing nature of the substituted endcap. Two regioisomers of the bridgehead-substituted endcap were isolated, and their chemical structures were elucidated by X-ray crystallography. The model compound and molecular modeling studies conducted ruled out the possibility of regioisomeric imide formation in the substituted endcaps. C1 NASA,LEWIS RES CTR,POLYMER SCI BRANCH,CLEVELAND,OH 44135. CASE WESTERN RESERVE UNIV,DEPT CHEM,CLEVELAND,OH 44106. RUTGERS STATE UNIV,DEPT CHEM,CAMDEN,NJ 08102. INDIANA STATE UNIV,DEPT CHEM,TERRE HAUTE,IN 47809. OI Meador, Mary Ann/0000-0003-2513-7372 NR 10 TC 7 Z9 8 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD JUL 20 PY 1992 VL 25 IS 15 BP 3868 EP 3873 DI 10.1021/ma00041a007 PG 6 WC Polymer Science SC Polymer Science GA JE746 UT WOS:A1992JE74600007 ER PT J AU IYONO, A TAKAHASHI, Y GREGORY, JC HAYASHI, T SHIINA, T CHRISTL, MJ DERRICKSON, JH FOUNTAIN, WF PARNELL, TA RUBIN, B WATTS, JW NAGAMIYA, S TOMINAGA, T DAKE, S FUKI, M OGATA, T MIYAMURA, O YOKOMI, H AF IYONO, A TAKAHASHI, Y GREGORY, JC HAYASHI, T SHIINA, T CHRISTL, MJ DERRICKSON, JH FOUNTAIN, WF PARNELL, TA RUBIN, B WATTS, JW NAGAMIYA, S TOMINAGA, T DAKE, S FUKI, M OGATA, T MIYAMURA, O YOKOMI, H TI RAPIDITY AND TRANSVERSE-MOMENTUM DISTRIBUTIONS IN 6.4-TEV S+PB INTERACTIONS FROM CERN EMU05 EXPERIMENTS SO NUCLEAR PHYSICS A LA English DT Article; Proceedings Paper CT 9TH INTERNATIONAL CONF ON ULTRA-RELATIVISTIC NUCLEUS-NUCLEUS COLLISIONS, QUARK MATTER 91 CY NOV 11-15, 1991 CL GATLINBURG, TN SP US DOE, NATL SCI FDN, UNIV TENNESSEE, DEPT PHYS, UNIV TENNESSEE, SCI ALLIANCE PROGRAM, BICRON, DIGITAL EQUIPMENT, HAMAMATSU, LECROY ID COLLISIONS AB Mixed transverse(PT) momentum and rapidity distributions of charged particles produced in 200 GeV/AMU heavy ion collisions are obtained with Magnetic-Interferometric-Emulsion-Chamber (MAGIC) by CERN-EMU05 experiments. The P(T) spectra at different rapidity regions showed no anomalous enhancement of low P(T) components over a conventional, single exponential function with slope values ranging from 160 to 200 MeV/C. C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. COLUMBIA UNIV,DEPT PHYS,NEW YORK,NY 10027. LOUISIANA STATE UNIV,BATON ROUGE,LA 70803. KOBE UNIV,DEPT PHYS,KOBE 657,JAPAN. KOCHI UNIV,KOCHI 780,JAPAN. UNIV TOKYO,INST COSM RAY RES,TANASHI,TOKYO 188,JAPAN. TEZUKAYAMA GAKUIN UNIV,NARA 631,JAPAN. HIROSHIMA UNIV,DEPT PHYS,HIROSHIMA 730,JAPAN. RP IYONO, A (reprint author), OKAYAMA UNIV SCI,OKAYAMA 700,JAPAN. NR 11 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0375-9474 J9 NUCL PHYS A JI Nucl. Phys. A PD JUL 20 PY 1992 VL 544 IS 1-2 BP C455 EP C458 PG 4 WC Physics, Nuclear SC Physics GA JJ974 UT WOS:A1992JJ97400037 ER PT J AU KEOGH, WJ BOOTHROYD, AI MARTIN, PG MIELKE, SL TRUHLAR, DG SCHWENKE, DW AF KEOGH, WJ BOOTHROYD, AI MARTIN, PG MIELKE, SL TRUHLAR, DG SCHWENKE, DW TI TRAJECTORY CALCULATIONS AND CONVERGED QUANTUM CROSS-SECTIONS FOR D+H2(UPSILON = 1, J = 1, E(REL) = 1.02 EV)-]HD(UPSILON' = 1, J')+H ON A NEW POTENTIAL-ENERGY SURFACE SO CHEMICAL PHYSICS LETTERS LA English DT Article ID STATE REACTION DYNAMICS; REACTION D+H2->HD+H; VARIATIONAL PRINCIPLE; CHEMICAL-REACTIONS; ANGULAR-MOMENTUM; H+H-2 REACTION; RATE CONSTANTS; + H; COLLISIONS; SCATTERING AB The state-to-state cross sections and partial cross sections for D + H-2(upsilon = j = 1, E(rel) = 1.02 eV) --> HD(upsilon' = 1) + H have been calculated by both converged quantum dynamics and quasiclassical trajectories for a new (BKMP), very accurate potential energy surface. Additional new trajectory calculations are also reported for two other potential energy surfaces and a lower collision energy. The results for the BKMP surface are very similar to those obtained earlier for the DMBE surface. In particular the calculated value of the average j' in the HD upsilon' = 1 product level is 8.2-8.4, as compared to an experimental value of 6.9. The calculated ratio of cross sections for producing j' = 7 and 10 is a factor of 3-4 lower than the experimental ratio. C1 UNIV MINNESOTA,DEPT CHEM,MINNEAPOLIS,MN 55455. UNIV TORONTO,DEPT CHEM,TORONTO M5S 1A1,ONTARIO,CANADA. UNIV TORONTO,CANADIAN INST,THEORET ASTROPHYS,TORONTO M5S 1A1,ONTARIO,CANADA. UNIV MINNESOTA,CHEM PHYS PROGRAM,MINNEAPOLIS,MN 55455. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 55 TC 28 Z9 28 U1 0 U2 3 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 JUL 17 PY 1992 VL 195 IS 2-3 BP 144 EP 152 DI 10.1016/0009-2614(92)86126-3 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JE926 UT WOS:A1992JE92600006 ER PT J AU PARTRIDGE, H BAUSCHLICHER, CW SODUPE, M LANGHOFF, SR AF PARTRIDGE, H BAUSCHLICHER, CW SODUPE, M LANGHOFF, SR TI THEORETICAL DETERMINATION OF THE ALKALI-METAL SUPEROXIDE BOND-ENERGIES SO CHEMICAL PHYSICS LETTERS LA English DT Article ID RESONANCE-ABSORPTION SPECTROSCOPY; GTO BASIS-SETS; OXYGEN MOLECULES; DISSOCIATION-ENERGIES; VAPORIZATION BEHAVIOR; MATRIX REACTIONS; 2ND-ROW ATOMS; RATE-CONSTANT; SODIUM; LITHIUM AB The bond dissociation energies for the alkali-metal superoxides have been computed using extensive Gaussian basis sets and treating electron correlation at the modified coupled-pair functional level. Our computed D0 values are 61.4, 37.2, 40.6, and 38.4 kcal/mol for LiO2, NaO2, KO2, and RbO2, respectively. These values, which are expected to be lower bounds and accurate to 2 kcal/mol, agree well with some of the older flame data, but rule out several recent experimental measurements. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 44 TC 43 Z9 43 U1 1 U2 7 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 JUL 17 PY 1992 VL 195 IS 2-3 BP 200 EP 206 DI 10.1016/0009-2614(92)86136-6 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JE926 UT WOS:A1992JE92600016 ER PT J AU NOOR, AK AF NOOR, AK TI MECHANICS OF ANISOTROPIC PLATES AND SHELLS - A NEW LOOK AT AN OLD SUBJECT SO COMPUTERS & STRUCTURES LA English DT Review ID MULTILAYERED COMPOSITE PLATES; PREDICTOR-CORRECTOR PROCEDURES; FREE-VIBRATION ANALYSES; STATE HEAT-CONDUCTION; MODEL-SIZE REDUCTION; EXPLOITING SYMMETRIES; RECTANGULAR-PLATES; REVOLUTION; STRESS; PANELS AB A number of aspects of the mechanics of anisotropic plates and shells are discussed. The topics covered include computational models of anisotropic plates and shells, consequences of anisotropy on deformation couplings, symmetry types, stress concentrations and edge effects, and importance of transverse shear deformation; recent applications and recent advances in the modeling and analysis of anisotropic plates and shells; and new research directions. RP UNIV VIRGINIA, NASA, LANGLEY RES CTR, CTR COMPUTAT STRUCT TECHNOL, HAMPTON, VA 23665 USA. NR 155 TC 18 Z9 18 U1 0 U2 3 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 JUL 17 PY 1992 VL 44 IS 3 BP 499 EP 514 DI 10.1016/0045-7949(92)90383-B PG 16 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA JK012 UT WOS:A1992JK01200001 ER PT J AU FOROUHAR, S KSENDZOV, A LARSSON, A TEMKIN, H AF FOROUHAR, S KSENDZOV, A LARSSON, A TEMKIN, H TI INGAAS/INGAASP/INP STRAINED-LAYER QUANTUM-WELL LASERS AT SIMILAR-TO-2-MU-M SO ELECTRONICS LETTERS LA English DT Article DE SEMICONDUCTOR LASERS; LASERS ID MICRO-M AB The first successful operation of InGaAs strained layer quantum well (SL-QW) injection lasers at approximately 2-mu-m is reported. The threshold current density and the external differential quantum efficiency of 5-mu-m wide and 800-mu-m long ridge waveguide lasers were 2.5 kA/cm2 and 6%, respectively. The devices had a reverse leakage current of less than 20-mu-A at -1 V indicating epitaxial layers with low defect density. C1 AT&T BELL LABS,MURRAY HILL,NJ 07974. RP FOROUHAR, S (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 10 TC 67 Z9 68 U1 1 U2 3 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD JUL 16 PY 1992 VL 28 IS 15 BP 1431 EP 1432 DI 10.1049/el:19920910 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA JF061 UT WOS:A1992JF06100038 ER PT J AU HE, XM CARTER, DC AF HE, XM CARTER, DC TI ATOMIC-STRUCTURE AND CHEMISTRY OF HUMAN SERUM-ALBUMIN SO NATURE LA English DT Article ID AMINO-ACID SEQUENCE; DRUG-BINDING-SITES; ALPHA-FETOPROTEIN; MACROMOLECULAR CRYSTALLOGRAPHY; NUCLEOTIDE-SEQUENCE; MESSENGER-RNA; VARIANTS; GENE; POPULATIONS; EXPRESSION AB The three-dimensional structure of human serum albumin has been determined crystallographically to a resolution of 2.8 angstrom. It comprises three homologous domains that assemble to form a heart-shaped molecule. Each domain is a product of two subdomains that possess common structural motifs. The principal regions of ligand binding to human serum albumin are located in hydrophobic cavities in subdomains IIA and IIIA, which exhibit similar chemistry. The structure explains numerous physical phenomena and should provide insight into future pharmacokinetic and genetically engineered therapeutic applications of serum albumin. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES76 BIOPHYS,HUNTSVILLE,AL 35812. NR 48 TC 2398 Z9 2460 U1 33 U2 238 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 16 PY 1992 VL 358 IS 6383 BP 209 EP 215 DI 10.1038/358209a0 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JD587 UT WOS:A1992JD58700045 PM 1630489 ER PT J AU CAMPBELL, L AF CAMPBELL, L TI DENSE GROUP NETWORKS SO DISCRETE APPLIED MATHEMATICS LA English DT Article DE CAYLEY GRAPH; GROUP; PARALLEL PROCESSING; INTERCONNECTION NETWORK AB Significant improvements have recently been made to many of the lower bounds for the largest graphs of given degree and diameter. A number of these improvements have been made by the author and others using Cayley graph constructions. This paper outlines these results and gives the generator sets for 17 new record constructions. RP CAMPBELL, L (reprint author), UNIV IDAHO,NASA,ENGN RES CTR,MOSCOW,ID 83843, USA. NR 8 TC 8 Z9 8 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0166-218X J9 DISCRETE APPL MATH JI Discret Appl. Math. PD JUL 15 PY 1992 VL 37-8 BP 65 EP 71 DI 10.1016/0166-218X(92)90125-T PG 7 WC Mathematics, Applied SC Mathematics GA JH950 UT WOS:A1992JH95000007 ER PT J AU MA, Q TIPPING, RH AF MA, Q TIPPING, RH TI A FAR WING LINE-SHAPE THEORY AND ITS APPLICATION TO THE FOREIGN-BROADENED WATER CONTINUUM ABSORPTION .3. SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID STATISTICAL-THEORY; ROTATIONAL BANDS; REGION; VAPOR AB The far wing line shape theory developed previously and applied to the calculation of the continuum absorption of pure water vapor is extended to foreign-broadened continua. Explicit results are given for H2O-N2 and H2O-CO2 in the frequency range from 0 to 10 000 cm-1. The theory is based on the quasistatic and binary collision approximations and assumes for the interaction potential an isotropic Lennard-Jones part and the leading anisotropic multipolar (dipole-quadrupole) term. For H2O-N2, the positive and negative resonant frequency average line shape functions and absorption coefficients are calculated for a number of temperatures between 296 and 430 K for comparison with existing laboratory data. In general, the agreement is very good, especially at the higher temperatures for which the experimental absorption is larger and the corresponding error limits are smaller. For H2O-CO2 for which no experimental data exists, the calculations are made only at 296 K. Because of the significantly different line shapes for self vs foreign broadening, the ratio of the corresponding continuum absorption coefficients varies widely as a function of the frequency. The implications of this for absorption in the Earth's atmosphere are discussed briefly. C1 UNIV ALABAMA,DEPT PHYS & ASTRON,TUSCALOOSA,AL 35487. GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. HARVARD SMITHSONIAN CTR ASTROPHYS,INST THEORET ATOM & MOLEC PHYS,CAMBRIDGE,MA 02138. RP MA, Q (reprint author), COLUMBIA UNIV,CTR STUDY GLOBAL HABITABIL,NEW YORK,NY 10025, USA. NR 16 TC 44 Z9 46 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUL 15 PY 1992 VL 97 IS 2 BP 818 EP 828 DI 10.1063/1.463184 PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JM253 UT WOS:A1992JM25300008 ER PT J AU GREEN, S MANNUCCI, AJ AF GREEN, S MANNUCCI, AJ TI HETERODYNE SPECTROSCOPY OF CARBON-MONOXIDE LINES PERTURBED BY HYDROGEN AND HELIUM - COMMENT SO JOURNAL OF CHEMICAL PHYSICS LA English DT Letter ID CO-HE; PRESSURE; PARAMETERS; BAND C1 JET PROP LAB,PASADENA,CA 91109. RP GREEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. RI Mannucci, Anthony/A-1349-2007 OI Mannucci, Anthony/0000-0003-2391-8490 NR 11 TC 8 Z9 8 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUL 15 PY 1992 VL 97 IS 2 BP 1610 EP 1611 DI 10.1063/1.463239 PG 2 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JM253 UT WOS:A1992JM25300094 ER PT J AU JACKSON, FC WALTON, WT HINES, DE WALTER, BA PENG, CY AF JACKSON, FC WALTON, WT HINES, DE WALTER, BA PENG, CY TI SEA-SURFACE MEAN-SQUARE SLOPE FROM K(U)-BAND BACKSCATTER DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GENERATED GRAVITY-WAVES; RADAR CROSS-SECTION; EQUILIBRIUM RANGE; ROUGH-SURFACE; WIND STRESS; SPECTRA; OCEAN; SCATTERING; DEPENDENCE; AIRCRAFT AB Near-nadir, quasi-specular backscatter data obtained with a 14-GHz airborne radar altimeter are analyzed in terms of the surface mean square slope (mss) parameter. The raw mss data, derived from a least squares fitting of a ray optical scattering model to the return waveform, show an approximately linear wind speed dependence over the wind speed range of 7-15 m s-1, with a slope of about one half that of the optically determined mss. Further analysis based on a simple two-scale scattering model indicates that, at the higher wind speeds, approximately 20% of this apparent slope signal can be attributed to diffraction from waves shorter than the estimated diffraction limit of approximately 0.10 m. The present slope data, as well as slope and other data from a variety of sources, are used to draw inferences on the structure of the high wavenumber portion of the wave spectrum. The data support a directionally integrated model height spectrum consisting of wind speed dependent k-5/2 and classical Phillips' k-3 power law subranges in the range of gravity waves, with a transition between the two subranges occurring around 10 times the peak wavenumber, and a Durden and Vesecky wind speed dependent spectrum in the gravity-capillary wave range. With a nominal value of the spectral constant A(u) = 0.002 in the first k-5/2 subrange, this equilibrium spectrum model predicts a mss wind speed dependence that accords with much of the available data at both microwave and optical frequencies. C1 NOAA,PACIFIC MARINE ENVIRONM LAB,SEATTLE,WA 98115. SCI SYST & APPLICAT INC,LANHAM,MD 20706. RP JACKSON, FC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS LAB,CODE 971,GREENBELT,MD 20771, USA. NR 75 TC 88 Z9 90 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 1992 VL 97 IS C7 BP 11411 EP 11427 DI 10.1029/92JC00766 PG 17 WC Oceanography SC Oceanography GA JE564 UT WOS:A1992JE56400018 ER PT J AU HOU, AY LINDZEN, RS AF HOU, AY LINDZEN, RS TI THE INFLUENCE OF CONCENTRATED HEATING ON THE HADLEY CIRCULATION SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article AB This study extends the earlier work on Hadley circulations forced by broad, global heating distributions to situations where heating is latitudinally concentrated. In the case of heating symmetrically centered on the equator, concentration unambiguously increases the intensity of the Hadley circulation-by up to a factor of 5. For heating centered off the equator, its effect depends on whether the concentration is drawn symmetrically from both sides of the heating maximum or whether the heat is preferentially drawn from the winter side. In the latter case, concentration again leads to pronounced intensification of the Hadley circulation. Indeed, agreement between the calculated and observed Hadley intensity is achieved with mild concentration, consistent with the observed zonally averaged precipitation, rather than the narrower rainfall association with the ITCZ. This suggests that a weakening of those processes that broaden the zonally averaged rainfall (i.e., the easterly waves and regional land processes) would result in a much stronger Hadley circulation. The implication of this work is that a small change in the tropical heating distribution can profoundly alter the intensity of the Hadley circulation and the baroclinicity in the extratropics. This can, in tum, modulate wave transport in the middle and high latitudes, resulting in significant changes in the global climate. C1 MIT,CTR METEOROL & PHYS OCEANOG,CAMBRIDGE,MA 02139. RP HOU, AY (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 9103,GREENBELT,MD 20771, USA. RI Hou, Arthur/D-8578-2012 NR 8 TC 68 Z9 70 U1 1 U2 8 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JUL 15 PY 1992 VL 49 IS 14 BP 1233 EP 1241 DI 10.1175/1520-0469(1992)049<1233:TIOCHO>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JD724 UT WOS:A1992JD72400005 ER PT J AU BRAND, HR DEISSLER, RJ AF BRAND, HR DEISSLER, RJ TI PROPAGATING CONFINED STATES IN PHASE DYNAMICS SO PHYSICAL REVIEW A LA English DT Article ID RAYLEIGH-BENARD CONVECTION; CIRCULAR COUETTE SYSTEM; TAYLOR INSTABILITY; FLOW; INTERMITTENCY; WAVES; NOISE AB We show that the nonlinear phase equation that applies to propagating patterns allows for a large range of parameter values for propagating confined states for which a spatially localized region with wavelengths different from that of the background travels on this background. This phenomenon is the generalization of the stationary confined states predicted a few years ago by the authors, which have since been seen experimentally in various systems. We suggest that the propagating confined states found here could arise in spirals in Taylor vortex flow or in convective systems showing traveling waves far above onset. We find that the propagating confined states can be replaced by a pattern that is irregular in space and time as the control parameter in the nonlinear phase equation is varied. C1 UNIV ESSEN GESAMTHSCH, DEPT PHYS, W-4300 ESSEN 1, GERMANY. NASA, LEWIS RES CTR, ICOMP, CLEVELAND, OH 44135 USA. RP BRAND, HR (reprint author), LOS ALAMOS NATL LAB, CTR NONLINEAR STUDIES, MAIL STOP B 258, LOS ALAMOS, NM 87545 USA. NR 31 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 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD JUL 15 PY 1992 VL 46 IS 2 BP 888 EP 892 DI 10.1103/PhysRevA.46.888 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA JF183 UT WOS:A1992JF18300027 ER PT J AU ZHOU, Y VAHALA, G AF ZHOU, Y VAHALA, G TI LOCAL INTERACTIONS IN RENORMALIZATION METHODS FOR NAVIER-STOKES TURBULENCE SO PHYSICAL REVIEW A LA English DT Note ID EDDY VISCOSITY; ISOTROPIC TURBULENCE; FLUID AB Two distinct renormalization-group (RNG) approaches have been applied to Navier-Stokes turbulence: epsilon-RNG and recursive RNG. Epsilon-RNG takes into account only nonlocal interactions and utilizes an infinitesimal subgrid (unresolvable scale) shell limit. Recursive RNG takes into account both nonlocal and local interactions and does not require an infinitesimal subgrid shell limit to be taken. The role of local interactions and the introduction of RNG-induced nonlinearities are discussed and clarified. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. RP ZHOU, Y (reprint author), STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305, USA. NR 17 TC 9 Z9 10 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD JUL 15 PY 1992 VL 46 IS 2 BP 1136 EP 1139 DI 10.1103/PhysRevA.46.1136 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA JF183 UT WOS:A1992JF18300059 ER PT J AU FREED, AD RAJ, SV WALKER, KP AF FREED, AD RAJ, SV WALKER, KP TI 3-DIMENSIONAL DEFORMATION ANALYSIS OF 2-PHASE DISLOCATION SUBSTRUCTURES SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 ENGN SCI SOFTWARE INC,SMITHFIELD,RI 02917. RP FREED, AD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. OI Freed, Alan/0000-0002-3492-0628 NR 22 TC 5 Z9 5 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD JUL 15 PY 1992 VL 27 IS 2 BP 233 EP 238 DI 10.1016/0956-716X(92)90119-Y PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA HZ526 UT WOS:A1992HZ52600020 ER PT J AU RICH, DH RAJKUMAR, KC CHEN, L MADHUKAR, A GRUNTHANER, FJ AF RICH, DH RAJKUMAR, KC CHEN, L MADHUKAR, A GRUNTHANER, FJ TI NEAR-INFRARED CATHODOLUMINESCENCE IMAGING OF DEFECT DISTRIBUTIONS IN IN0.2GA0.8AS/GAAS MULTIPLE QUANTUM-WELLS GROWN ON PREPATTERNED GAAS SO APPLIED PHYSICS LETTERS LA English DT Article ID REDUCTION AB The defect distribution in a highly strained In0.2Gao.8As/GaAs multiple-quantum-well (MQW) structure grown on a patterned GaAs substrate is examined with cathodoluminescence imaging and spectroscopy in the near infrared. By spatially correlating the luminescence arising from the MQW exciton recombination (lambda almost-equal-to 950 nm) with the longer wavelength (1000 less-than-or-similar lambda less-than-or-similar 1200 nm) luminescence arising from the defect-induced recombination, we demonstrate that it is possible to determine the regions of highest film quality in both the mesa and valley regions. The present approach enables a judicious determination of the optimal regions to be used for active pixels in InGaAs/GaAs spatial light modulators. C1 UNIV SO CALIF,DEPT PHYS,LOS ANGELES,CA 90089. CALTECH,CTR SPACE MICROELECTR TECHNOL,JET PROPULS LAB,PASADENA,CA 91109. RP RICH, DH (reprint author), UNIV SO CALIF,DEPT MAT SCI & ENGN,PHOTON MAT & DEVICES LAB,LOS ANGELES,CA 90089, USA. NR 11 TC 13 Z9 13 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 13 PY 1992 VL 61 IS 2 BP 222 EP 224 DI 10.1063/1.108225 PG 3 WC Physics, Applied SC Physics GA JD352 UT WOS:A1992JD35200035 ER PT J AU MILLER, RH SMITH, BF AF MILLER, RH SMITH, BF TI OFF-CENTER NUCLEI IN GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, KINEMATICS AND DYNAMICS; GALAXIES, NUCLEI; METHODS, NUMERICAL; VIDEOTAPES ID DYNAMICAL FRICTION; SINKING SATELLITES; M31; SIMULATIONS; KINEMATICS; ORBITS; DECAY; GAS AB The nucleus of a galaxy orbits around the mass centroid. Orbital motions appear overstable in numerical experiments started with a galaxy's nucleus at rest atop its mass centroid. The amplitude doubles in 6-10 orbital periods. Orbits precess, nutate, and change their amplitudes, but they keep fairly constant periods. Orbital periods are in resonance with local particle motions, and amplitudes reach a core radius. This resonance suggests that center motions are a local, rather than a global, phenomenon. The overstability implies that a galaxy cannot be formed in nature with its nucleus at rest atop its mass centroid, and that nuclei orbit the mass centroid in real galaxies. These center motions should show up observationally as a shift of the nucleus away from the center defined by nearby isophotes. Off-center nuclei have been reported in many galaxies (e.g., M33, M101, NGC 3379, NGC 3384 ...). Other kinds of observations confirmed the picture of nonsteady galactic centers as well. Gas trapped in moving nuclear regions of a galaxy should show strange flow patterns with possible shocks. The nuclear regions of galaxies including our own and of globular clusters are not likely to be in a static steady state. C1 NASA,AMES RES CTR,THEORET STUDIES BRANCH,MOFFETT FIELD,CA 94035. RP MILLER, RH (reprint author), UNIV CHICAGO,CTR ASTRON,DEPT ASTRON & ASTROPHYS,5640 ELLIS AVE,CHICAGO,IL 60637, USA. NR 41 TC 56 Z9 56 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1992 VL 393 IS 2 BP 508 EP 515 DI 10.1086/171523 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA516 UT WOS:A1992JA51600009 ER PT J AU STEINACKER, J MILLER, JA AF STEINACKER, J MILLER, JA TI STOCHASTIC GYRORESONANT ELECTRON ACCELERATION IN A LOW-BETA PLASMA .1. INTERACTION WITH PARALLEL TRANSVERSE COLD-PLASMA WAVES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; MHD; PLASMAS; SUN, FLARES; SUN, PARTICLE EMISSION ID AMPLITUDE ALFVEN WAVES; IMPULSIVE SOLAR-FLARES; PARTICLE-ACCELERATION; COSMIC-RAYS; MAGNETIC RECONNECTION; INTERPLANETARY MEDIUM; KINETIC-EQUATION; WIND; TURBULENCE; SCATTERING AB We consider the gyroresonance of electrons with parallel transverse cold plasma waves and derive the Fokker-Planck equation describing the evolution of the electron distribution function in the presence of a spectrum of turbulence. We take into account all such modes, which include nondispersive Alfven as well as dispersive whistler and cyclotron waves, and also employ the full gyroresonance condition. We have identified a new resonance which produces a divergence in the Fokker-Planck coefficients; it results when the electron is in gyroresonance with a wave that has a group velocity equal to the velocity of the electron along the magnetic field. Assuming a power-law spectral density, we numerically calculate the Fokker-Planck coefficients and discuss their complicated momentum and pitch-angle dependence, as well as the influence of various approximations to the dispersion relation, gyroresonance condition, and spectral density. We find that there is no resonance gap at any pitch angle as long as the full gyroresonance condition is used and waves propagating in both directions are present. In solar flares, waves near the electron cyclotron frequency, whistlers, and Alfven waves are the most important resonant waves for the energization of nonrelativistic, relativistic, and ultrarelativistic electrons, respectively. The time scale for acceleration to highly relativistic energies is approximately 1 s for reasonable flare conditions. The precise threshold energy, however, depends upon thermal modifications to the cold plasma dispersion relation around the electron cyclotron frequency, but should lie in the tail of the Maxwellian. In this nonrelativistic region, the pitch-angle scattering and momentum diffusion time scales are comparable, producing a breakdown in the commonly used momentum diffusion equation. RP STEINACKER, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 665,GREENBELT,MD 20771, USA. NR 109 TC 84 Z9 84 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1992 VL 393 IS 2 BP 764 EP 781 DI 10.1086/171544 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA516 UT WOS:A1992JA51600030 ER PT J AU DESAI, KM GWINN, CR REYNOLDS, J KING, EA JAUNCEY, D FLANAGAN, C NICOLSON, G PRESTON, RA JONES, DL AF DESAI, KM GWINN, CR REYNOLDS, J KING, EA JAUNCEY, D FLANAGAN, C NICOLSON, G PRESTON, RA JONES, DL TI A SPECKLE HOLOGRAM OF THE INTERSTELLAR PLASMA SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; TECHNIQUES, INTERFEROMETRIC; PULSARS, INDIVIDUAL, VELA PULSAR; SUPERNOVA REMNANTS ID SCINTILLATION; ACCELERATION; SCATTERING; PULSAR AB Observations of a speckle hologram of scattering material along the line of sight to the Vela pulsar indicate that this material is concentrated in the Vela supernova remnant, deep within the Gum Nebula. The speckle hologram is observed through the amplitude and phase variations of the interferometric cross-power spectrum with time and frequency. These variations describe the density fluctuations of the interstellar plasma, in a holographic fashion. The decorrelation due to the phase variations of the speckles yields the angular size of the scattering disk; comparison with the bandwidth of their amplitude variations yields a characteristic distance from Earth to the scattering material of 0.81 +/- 0.03 of the distance from Earth to the pulsar. Our result is consistent with theories of irregularities associated with particle acceleration in shocks in supernova remnants. C1 CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. UNIV TASMANIA,DEPT PHYS,HOBART,TAS 7001,AUSTRALIA. HARTEBEESTHOEK RADIO ASTRON OBSERV,KRUGERSDORP 1740,SOUTH AFRICA. JET PROP LAB,PASADENA,CA 91109. RP DESAI, KM (reprint author), UNIV CALIF SANTA BARBARA,DEPT PHYS,SANTA BARBARA,CA 93106, USA. RI King, Edward/A-1473-2012 OI King, Edward/0000-0002-6898-2130 NR 24 TC 26 Z9 26 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1992 VL 393 IS 2 BP L75 EP & DI 10.1086/186455 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA517 UT WOS:A1992JA51700009 ER PT J AU SCHAEFER, BE TEEGARDEN, BJ CLINE, TL FISHMAN, GJ MEEGAN, CA WILSON, RB PACIESAS, WS PENDLETON, GN MATTESON, JL BAND, DL LESTRADE, JP AF SCHAEFER, BE TEEGARDEN, BJ CLINE, TL FISHMAN, GJ MEEGAN, CA WILSON, RB PACIESAS, WS PENDLETON, GN MATTESON, JL BAND, DL LESTRADE, JP TI HIGH-ENERGY SPECTRAL BREAKS IN GAMMA-RAY BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, BURSTS ID PHOTON AB We present model fits for 18 gamma-ray burst spectra from 100 keV to 27 MeV made with the BATSE spectroscopy detectors on the Compton Gamma Ray Observatory. Most of the bursts are well fitted as power laws with spectral indices between -1.36 and -2.29; however, five bursts show definite departures from a simple power-law fit at high energies. Three of these bursts are well fitted with broken power-law spectra and break energies of from 400 to 690 keV, such as might arise from photon-photon interactions. If so, then the source compactness and hence distance will be sharply constrained. Two of the bursts have spectra with sharply confined slope changes and are well fitted with broken power-law spectra with break energies of 1.2 and 1.6 MeV at peak, such as might arise from photon-magnetic field interactions. If so, then these spectral breaks provide strong evidence for the existence of high magnetic fields in the burst emission region. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV CALIF SAN DIEGO,LA JOLLA,CA 92093. MISSISSIPPI STATE UNIV,MISSISSIPPI STATE,MS 39762. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 13 TC 56 Z9 56 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1992 VL 393 IS 2 BP L51 EP L54 DI 10.1086/186449 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA517 UT WOS:A1992JA51700003 ER PT J AU CIBULA, WG ZETKA, EF RICKMAN, DL AF CIBULA, WG ZETKA, EF RICKMAN, DL TI RESPONSE OF THEMATIC MAPPER BANDS TO PLANT WATER-STRESS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID LEAVES AB Changes in leaf reflectance as water content decreases have been hypothesized to occur in the 1.55-1.75 and 2.08-2.35-mu-m wavelength regions. To evaluate this hypothesis, studies were conducted on ryegrass (Lolium multiflorum Lam.) and oats (Avena sativa L.), which were grown in a controlled, outdoor situation. Both fully-watered control beds and water-stressed beds were periodically examined with a spectroradiometer calibrated against a reflectance reference of polytetrafluoroethylene. The observed changes correspond to those predicted by stochastic leaf models employed by other investigators (leaf reflection increases in the 1.55-1.75-mu-m region as leaf water content decreases). Although the percentage changes in TM bands 1-3 are nearly as great as those found in TM bands 5 and 7, the absolute values of reflectance change are much lower. We believe that these patterns are probably characteristic of a broad range of vegetation types. In terms of phenomena detection, these patterns should be considered in any practical remote sensing sensor scenario. RP CIBULA, WG (reprint author), NASA,SCI & TECHNOL LAB,BAY ST LOUIS,MS 39529, USA. OI Rickman, Doug/0000-0003-3409-2882 NR 32 TC 39 Z9 43 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 10 PY 1992 VL 13 IS 10 BP 1869 EP 1880 PG 12 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA JC998 UT WOS:A1992JC99800006 ER PT J AU RIND, D ROSENZWEIG, C GOLDBERG, R AF RIND, D ROSENZWEIG, C GOLDBERG, R TI MODELING THE HYDROLOGICAL CYCLE IN ASSESSMENTS OF CLIMATE CHANGE SO NATURE LA English DT Review AB Climate change caused by increasing atmospheric concentrations of greenhouse gases may have important effects on water circulation and availability and thus on agriculture, forestry and river flow, with significant economic consequences. A variety of models are being used to evaluate hydrological effects, but their hydrological responses to global warming are often inconsistent. Improved understanding of basic hydrological processes is needed if we are to assess the impact of future climate change. C1 COLUMBIA UNIV,CTR GLOBAL HABITABIL,NEW YORK,NY 10027. RP RIND, D (reprint author), NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 28 TC 47 Z9 50 U1 7 U2 15 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 9 PY 1992 VL 358 IS 6382 BP 119 EP 122 DI 10.1038/358119a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JC583 UT WOS:A1992JC58300041 ER PT J AU HILSENRATH, E CEBULA, RP JACKMAN, CH AF HILSENRATH, E CEBULA, RP JACKMAN, CH TI OZONE DEPLETION IN THE UPPER-STRATOSPHERE ESTIMATED FROM SATELLITE AND SPACE-SHUTTLE DATA SO NATURE LA English DT Article ID MODEL AB WHEN the possibility of anthropogenic ozone depletion was first identified, it was thought that it would occur primarily in the upper stratosphere, at altitudes near 42 km. It is now recognized that ozone losses due to heterogeneous reactions involving chlorine and bromine 1 are greatest in the lower stratosphere, near 20 km (ref. 2), and this is the main cause of ozone depletion over polar latitudes 3. Despite satellite observation of the upper stratosphere for nearly a decade 4, the question of possible ozone depletion in this region has remained unresolved because of instrument degradation and incomplete monitoring 5. Recent observations of ozone concentrations in the upper stratosphere have been made with the Shuttle Solar Backscatter Ultraviolet (SSBUV) spectrometer carried by the Space Shuttle. Here we combine the SSBUV data for October 1989 with measurements made in October 1980 by the similar SBUV instrument on NASA's Nimbus-7 satellite, to show that the ozone concentration near 45 km has decreased during this period by about 7 +/- 2%. The trend is consistent with the predictions of a two-dimensional photochemical model. Although this contribution to total column ozone depletion is small, the changes may have implications for the radiative properties of the upper atmosphere. C1 HUGHES STX CORP,LANHAM,MD 20706. RP HILSENRATH, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Jackman, Charles/D-4699-2012 NR 16 TC 15 Z9 15 U1 0 U2 3 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 9 PY 1992 VL 358 IS 6382 BP 131 EP 133 DI 10.1038/358131a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JC583 UT WOS:A1992JC58300044 ER PT J AU DEMORE, WB AF DEMORE, WB TI RELATIVE RATE CONSTANTS FOR THE REACTIONS OF OH WITH METHANE AND METHYL CHLOROFORM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Atmospheric lifetimes of methane and methyl chloroform are largely determined by the rates of their reactions with hydroxyl radical. The relative lifetimes for this loss path are inversely proportional to the ratio of the corresponding rate coefficients. In this work the relative rate constants were measured in a slow-flow, temperature controlled photochemical reactor, and were based on rates of disappearance of the parent compounds as measured by FTIR spectroscopy. The temperature range was 277-356 K. Hydroxyl radicals were generated by 254 nm photolysis of O3 in the presence of water vapor. The preferred Arrhenius expression for the results is k(CH3CCl3)/k(CH4) = 0.62exp(291/T), corresponding to a value of 1.65 at 298 K and 1.77 at 277 K. The respective uncertainties are 5% and 7%. RP DEMORE, WB (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 11 TC 23 Z9 24 U1 4 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 6 PY 1992 VL 19 IS 13 BP 1367 EP 1370 DI 10.1029/92GL01278 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JC596 UT WOS:A1992JC59600012 ER PT J AU YOUNG, PG MENA, RA ALTEROVITZ, SA SCHACHAM, SE HAUGLAND, EJ AF YOUNG, PG MENA, RA ALTEROVITZ, SA SCHACHAM, SE HAUGLAND, EJ TI TEMPERATURE INDEPENDENT QUANTUM-WELL FET WITH DELTA CHANNEL DOPING SO ELECTRONICS LETTERS LA English DT Article DE FIELD-EFFECT TRANSISTORS; TRANSISTORS; SEMICONDUCTOR DEVICES AND MATERIALS AB A temperature independent device is presented which uses a quantum well structure and delta doping within the channel. The device requires a high delta doping concentration within the channel to achieve a constant Hall mobility and carrier concentration across the temperature range 300-1-4 K. Transistors were RF tested using on-wafer probing and a constant G(max) and F(max) were measured over the temperature range 300-70 K. C1 UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606. TECHNION ISRAEL INST TECHNOL,DEPT ELECT ENGN,IL-32000 HAIFA,ISRAEL. RP YOUNG, PG (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 5 TC 5 Z9 5 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD JUL 2 PY 1992 VL 28 IS 14 BP 1352 EP 1354 DI 10.1049/el:19920858 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA JD103 UT WOS:A1992JD10300042 ER PT J AU TSURUTANI, BT GONZALEZ, WD AF TSURUTANI, BT GONZALEZ, WD TI TWEAKING THE MAGNETOSPHERE SO NATURE LA English DT Letter ID MAGNETIC STORMS; INTERPLANETARY; DST C1 INST NATL PESQUISAS ESPACIAIS,SAO JOSE CAMPOS,SP,BRAZIL. RP TSURUTANI, BT (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 9 TC 1 Z9 1 U1 0 U2 1 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 2 PY 1992 VL 358 IS 6381 BP 26 EP 26 DI 10.1038/358026a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JB341 UT WOS:A1992JB34100037 ER PT J AU SALAMA, F ALLAMANDOLA, LJ AF SALAMA, F ALLAMANDOLA, LJ TI IS A PYRENE-LIKE MOLECULAR ION THE CAUSE OF THE 4,430-ANGSTROM DIFFUSE INTERSTELLAR ABSORPTION-BAND SO NATURE LA English DT Article ID POLYCYCLIC AROMATIC-HYDROCARBONS; EMISSION; SPECTRA; NAPHTHALENE; FEATURES; RADICALS AB THE diffuse interstellar bands (DIBs), ubiquitous absorption features in astronomical spectra, have been known since early this century 1 and now number more than a hundred. Ranging from 4,400 angstrom to the near infrared 2, they differ markedly in depth, width and shape, making the concept of a single carrier unlikely. Whether they are due to gas or grains is not settled, but recent results 3 suggest that the DIB carriers are quite separate from the grains that cause visual extinction. Among molecular candidates the polycyclic aromatic hydrocarbons (PAHs) have been proposed as the possible carriers of some of the DIBs 4-7, and we present here laboratory measurements of the optical spectrum of the pyrene cation C16H10+ in neon and argon. matrices. The strongest absorption feature falls at 4,435 +/- 5 angstrom in the argon matrix and 4,395 +/- 5 angstrom in the neon matrix, both close to the strong 4,430-angstrom DIB. If this or a related pyrene-like species is responsible for this particular band, it must account for 0.2% of all cosmic carbon. The ion also shows an intense but puzzling broad continuum, extending from the ultraviolet to the visible, similar to what is seen in the naphthalene cation 8 and perhaps therefore a common feature of all PAH cations. This may provide an explanation of how PAHs convert a large fraction of interstellar radiation from ultraviolet and visible wavelengths down to the infrared. RP SALAMA, F (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-6,MOFFETT FIELD,CA 94035, USA. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 24 TC 86 Z9 86 U1 1 U2 8 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 2 PY 1992 VL 358 IS 6381 BP 42 EP 43 DI 10.1038/358042a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JB341 UT WOS:A1992JB34100045 PM 11536498 ER PT J AU LEBLANC, A SCHNEIDER, V AF LEBLANC, A SCHNEIDER, V TI COUNTERMEASURES AGAINST SPACE-FLIGHT RELATED BONE LOSS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 9TH INTERNATIONAL SYMP ON MAN IN SPACE CY JUN 17-21, 1991 CL COLOGNE, GERMANY SP INT ACAD ASTRONAUT, INT ASTRONAUT FEDERAT, GERMAN SPACE AGCY, GERMAN AEROSP RES ESTAB, GERMAN SOC AERONAUT & ASTRONAUT, CTR NATL ETUDES SPATIALES, EUROPEAN SPACE AGCY, NASA AB This paper reviews human data concerning bone loss and attempted countermeasures during spaceflight and bed rest, a commonly employed technique to simulate the effects of weightlessness on the musculoskeletal system. RP LEBLANC, A (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 14 Z9 14 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1992 VL 27 BP 89 EP 92 DI 10.1016/0094-5765(92)90182-I PG 4 WC Engineering, Aerospace SC Engineering GA JF554 UT WOS:A1992JF55400017 PM 11537604 ER PT J AU BOY, GA AF BOY, GA TI INTEGRATED HUMAN-MACHINE INTELLIGENCE IN SPACE SYSTEMS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 9TH INTERNATIONAL SYMP ON MAN IN SPACE CY JUN 17-21, 1991 CL COLOGNE, GERMANY SP INT ACAD ASTRONAUT, INT ASTRONAUT FEDERAT, GERMAN SPACE AGCY, GERMAN AEROSP RES ESTAB, GERMAN SOC AERONAUT & ASTRONAUT, CTR NATL ETUDES SPATIALES, EUROPEAN SPACE AGCY, NASA AB This paper presents an artificial intelligence approach to integrated human-machine intelligence in space systems. It discusses the motivations for Intelligent Assistant Systems in both nominal and abnormal situations, The problem of constructing procedures is shown to be a very critical issue. in particular, keeping procedural experience in both design and operation is critical. We suggest what artificial intelligence can offer in this direction. Some crucial problems induced by this approach are discussed in detail. Finally, we analyze the various roles that would be shared by both astronauts, ground operators, and the intelligent assistant system. RP BOY, GA (reprint author), NASA,AMES RES CTR,ARTIFICIAL INTELLIGENCE RES BRANCH,STERLING FED SYST,MAIL STOP 244-17,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1992 VL 27 BP 175 EP 183 DI 10.1016/0094-5765(92)90195-O PG 9 WC Engineering, Aerospace SC Engineering GA JF554 UT WOS:A1992JF55400030 PM 11537584 ER PT J AU LOFTUS, JP KESSLER, DJ ANZMEADOR, PD AF LOFTUS, JP KESSLER, DJ ANZMEADOR, PD TI MANAGEMENT OF THE ORBITAL ENVIRONMENT SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 05-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB Man's activity in space has generated significant amounts of debris that remain in orbit for periods of sufficient duration to become a hazard to future space activities. In the past, the debris has been generated by inadvertent explosions of upper stages and spacecraft, by intentional explosions for military reasons, and possibly by a few breakups resulting from collisions. In the future, debris can be generated by collisions among spacecraft as the number of orbital objects continues to grow at rates greater than natural forces remove them from orbit. There are design and operations practices that can minimize the inadvertent generation of debris. There are other design and operations options for removing objects from space at the end of their useful service so they are not available as a source for the generation of future debris. Those studies are the primary concern of this paper. The issues are different in the low Earth orbits and in the geosynchronous orbits. In low Earth orbit, the hazards generated by potential collisions among spacecraft are severe because the events would take place at such high velocities. In geosynchronous orbit, the collision consequence is not so severe, because the relative velocities are low- < 1 km/s. But, because of the value of the limited arc and the extremely long lifetime of the satellites, it is necessary to remove any debris generated in the orbit to a different orbit at the end of life if it is to be no hazard to future operational spacecraft. The issue at present seems to be how high the reboost maneuver must be and what the maneuver strategy should be to ensure its effectiveness. The most economic removal of objects is achieved when those objects have the capability to execute the necessary maneuvers with their own systems and resources. The most costly option is to have some other system remove the spacecraft after it has become a derelict. Numerous options are being studied to develop systems and techniques that can remove spacecraft from useful orbits at the end of their useful life and do so for the least mass penalty and economic cost. RP LOFTUS, JP (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1992 VL 26 IS 7 BP 477 EP 486 DI 10.1016/0094-5765(92)90118-3 PG 10 WC Engineering, Aerospace SC Engineering GA JJ944 UT WOS:A1992JJ94400003 ER PT J AU BENSON, J STONE, E AF BENSON, J STONE, E TI FACE TO FACE - WITH STONE,EDWARD SO AEROSPACE AMERICA LA English DT Editorial Material C1 JET PROP LAB,PASADENA,CA 91109. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1992 VL 30 IS 7 BP 6 EP & PG 0 WC Engineering, Aerospace SC Engineering GA JD130 UT WOS:A1992JD13000002 ER PT J AU SMELSER, JW CONSTANTINE, MT AF SMELSER, JW CONSTANTINE, MT TI STME - STREAMLINING THE ENGINE OF CHANGE SO AEROSPACE AMERICA LA English DT Article RP SMELSER, JW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HEAVY LIFT LAUNCH VEHICLE OFF,STME SYST,HUNTSVILLE,AL 35812, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1992 VL 30 IS 7 BP 22 EP 25 PG 4 WC Engineering, Aerospace SC Engineering GA JD130 UT WOS:A1992JD13000006 ER PT J AU MITCHELL, R THOMAS, J LEVINSKY, C AF MITCHELL, R THOMAS, J LEVINSKY, C TI ASRM - TURNING IN A SOLID PERFORMANCE SO AEROSPACE AMERICA LA English DT Article RP MITCHELL, R (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ASRM PROJECT,HUNTSVILLE,AL 35812, USA. NR 0 TC 20 Z9 20 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1992 VL 30 IS 7 BP 26 EP & PG 0 WC Engineering, Aerospace SC Engineering GA JD130 UT WOS:A1992JD13000007 ER PT J AU COOK, JR GOLDBERG, BE ESTEY, PN WILEY, DR AF COOK, JR GOLDBERG, BE ESTEY, PN WILEY, DR TI HYBRID ROCKETS - COMBINING THE BEST OF LIQUIDS AND SOLIDS SO AEROSPACE AMERICA LA English DT Article RP COOK, JR (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SOLID PROPULS BRANCH,HUNTSVILLE,AL 35812, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1992 VL 30 IS 7 BP 30 EP & PG 0 WC Engineering, Aerospace SC Engineering GA JD130 UT WOS:A1992JD13000008 ER PT J AU BOROWSKI, SK CLARK, JS MCILWAIN, MC PELACCIO, DG AF BOROWSKI, SK CLARK, JS MCILWAIN, MC PELACCIO, DG TI NUCLEAR THERMAL ROCKETS - KEY TO MOON-MARS EXPLORATION SO AEROSPACE AMERICA LA English DT Article RP BOROWSKI, SK (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 1 Z9 1 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1992 VL 30 IS 7 BP 34 EP & PG 0 WC Engineering, Aerospace SC Engineering GA JD130 UT WOS:A1992JD13000009 ER PT J AU HOLLOWAY, PF AF HOLLOWAY, PF TI THE NATION NEEDS A RENEWED COMMITMENT TO AEROSPACE SO AEROSPACE AMERICA LA English DT Article RP HOLLOWAY, PF (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1992 VL 30 IS 7 BP B32 EP B32 PG 1 WC Engineering, Aerospace SC Engineering GA JD130 UT WOS:A1992JD13000016 ER PT J AU ECK, TF DEERING, DW AF ECK, TF DEERING, DW TI CANOPY ALBEDO AND TRANSMITTANCE IN A SPRUCE-HEMLOCK FOREST IN MID-SEPTEMBER SO AGRICULTURAL AND FOREST METEOROLOGY LA English DT Article ID RADIATION AB The short-wave radiation balance of a forest stand of predominantly spruce and hemlock in central Maine during 2 days in mid-September was investigated. Pyranometer measurements of insolation, reflected solar radiation from the top of the canopy, radiation incident on the forest floor, and radiation reflected from the forest floor were taken under both cloudless sky conditions and overcast cloud conditions. Measurements were made on two consecutive days to insure minimal change in forest canopy characteristics. The canopy albedo computed from half-day radiation totals, and thus representative of a daily value, was 10.8% on the clear day and 9.8% on the overcast day. The instantaneous albedo on the clear day ranged from 8.7% at 43-degrees solar zenith angle (solar noon) to 20.1% at 78-degrees solar zenith angle, and on the overcast day the albedo was relatively constant as a result of the diffuse irradiance condition. Canopy transmittance for the daily period was 2.9% on the clear day and 4.2% on the overcast day. The canopy transmittance was nearly constant throughout the day on the overcast day at about 4.2%, whereas sunfleck penetration on the clear day resulted in a higher transmittance of 4.5% from 43 to 47-degrees solar zenith angles, which dropped to 1.8% at 68-72-degrees solar zenith angles. Thus over the entire day, for the range of solar zenith angles measured, diffuse radiation on the overcast day penetrated further down into the forest canopy than the predominantly direct radiation on the clear day. It should be noted, however, that during the summer, when the solar zenith angle is lower at solar noon, the reverse may be true as a result of direct solar radiation penetration into thc canopy gaps. The forest floor albedo was similar on both days at about 19%, resulting in about 2.4% of the total insolation being absorbed by the ground below the forest canopy on the clear day, and 3.4% on the overcast day. C1 NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. RP ECK, TF (reprint author), HUGHES STX CORP,4400 FORBES BLVD,LANHAM,MD 20706, USA. RI ECK, THOMAS/D-7407-2012 NR 10 TC 15 Z9 16 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1923 J9 AGR FOREST METEOROL JI Agric. For. Meteorol. PD JUL PY 1992 VL 59 IS 3-4 BP 237 EP 248 DI 10.1016/0168-1923(92)90095-L PG 12 WC Agronomy; Forestry; Meteorology & Atmospheric Sciences SC Agriculture; Forestry; Meteorology & Atmospheric Sciences GA JJ982 UT WOS:A1992JJ98200007 ER PT J AU DUNN, MH FARASSAT, F AF DUNN, MH FARASSAT, F TI HIGH-SPEED PROPELLER NOISE PREDICTION - A MULTIDISCIPLINARY APPROACH SO AIAA JOURNAL LA English DT Article AB The prediction of noise produced by advanced propellers is a multidisciplinary subject which involves the aeroelasticity, aerodynamics, and aeroacoustics of rotating blades. As part of the PTA (Propfan Test Assessment) noise-prediction project of NASA Langley, state-of-the-art computational methods in these disciplines were combined to form a comprehensive propeller noise-prediction package. The primary function of the project was to assess current noise-prediction capability. This was accomplished by comparing predictions with the extensive noise data provided by the PTA flight tests of NASA Lewis. The emphasis of this paper is on free-field predictions, which correspond to boom microphone measurements, and conditions for which the inflow is approximately axial. Predictions made on the fuselage of the PTA aircraft and predictions corresponding to nonaxial inflow conditions form the subject matter of companion papers by the authors and co-workers. Excellent agreement in trends and generally good agreement in acoustic levels between free-field measured and predicted data were observed. A secondary goal of a the project was to study systematically the effect of blade deformation on propeller aerodynamics and acoustics. The twist and camber distributions of advanced propellers are altered by centrifugal and aerodynamic forces. Consequently, blade surface pressure, power, and thrust are influenced by blade deformation. It was demonstrated that the impact of blade deformation on propeller noise can be significant and should be included. C1 NASA,LANGLEY RES CTR,APPL ACOUST BRANCH,HAMPTON,VA 23665. RP DUNN, MH (reprint author), LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666, USA. NR 20 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1716 EP 1723 DI 10.2514/3.11128 PG 8 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600006 ER PT J AU WATSON, WR MYERS, MK AF WATSON, WR MYERS, MK TI 2-STEP METHOD FOR EVOLVING NONLINEAR ACOUSTIC SYSTEMS TO A STEADY-STATE SO AIAA JOURNAL LA English DT Article AB A two-step method for evolving two-dimensional nonlinear acoustic systems with flow to a periodic steady state is presented. In the first step of the method, the full nonlinear system governing acoustic disturbances is integrated numerically starting with arbitrary initial conditions using the explicit predictor-corrector method developed by MacCormack. In the second step, the Fourier Time Transform of the computed field is calculated to determine its frequency components. The transient wave field is then filtered from the spectrum and the inverse transform taken to provide an approximation to the steady-state wave field. This approximate field provides a new initial condition for subsequent iterations on the method. The method is tested on a benchmark acoustic problem for which exact steady-state solutions are known and on a nonlinear problem for which a steady-state solution has not been given before. Excellent agreement with the benchmark acoustic solution was obtained within four iterations for planar and nonplanar sources. Convergence to a steady state for the nonlinear problem occurred in six iterations. The two-step method eliminates the need to develop nonreflecting boundary conditions in order to obtain periodic steady-state solutions of two-dimensional acoustic problems and is easily extended to any number of spatial dimensions and to other hyperbolic systems. The procedure is shown to be numerically stable and may provide the only alternative for obtaining steady-state solutions to problems for which nonreflecting boundary conditions are not known or are physically incorrect. C1 GEORGE WASHINGTON UNIV,WASHINGTON,DC 20052. RP WATSON, WR (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST,APPL ACOUST BRANCH,MAIL STOP 460,HAMPTON,VA 23665, USA. NR 14 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1724 EP 1730 DI 10.2514/3.11129 PG 7 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600007 ER PT J AU TAM, CKW CHEN, P SEINER, JM AF TAM, CKW CHEN, P SEINER, JM TI RELATIONSHIP BETWEEN INSTABILITY WAVES AND NOISE OF HIGH-SPEED JETS SO AIAA JOURNAL LA English DT Article ID SUPERSONIC FLOWS AB The relationship between the instability waves and noise of hot jets at moderate supersonic Mach number is examined. For very-high-speed jets the instability waves propagate downstream with supersonic velocity relative to ambient sound speed. These fast moving instability waves generate intense Mach wave radiation (analogous to the case of supersonic flow past a wavy wall). Under this circumstance the radiated noise characteristics must strongly correlate with those of the instability waves. It is found that the highest sound-pressure level of the far-field noise occurs at a direction and frequency that closely match the Mach wave radiation direction and frequency of the most amplified instability wave of the jet. When the jet speed exceeds the sum of the sound speed inside and outside the jet, the jet flow supports not only the familiar Kelvin-Helmholtz instability waves but also a family of supersonic instability waves. Present calculations show that for jet Mach number up to 2.0 and jet total temperature to ambient temperature ratio up to 2.5, the Kelvin-Helmholtz instability waves always grow to a higher amplitude than the supersonic instability waves. Numerical results indicate that for hot jets the. most amplified wave invariably belongs to the helical mode Kelvin-Helmholtz instability wave. For lower speed hot jets with jet static temperature higher than or equal to the ambient temperature there is also a fair correlation between the Strouhal number at the peak sound-pressure level of the far-field noise and that of the most amplified instability wave. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP TAM, CKW (reprint author), FLORIDA STATE UNIV,DEPT MATH,TALLAHASSEE,FL 32306, USA. NR 10 TC 27 Z9 28 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1747 EP 1752 DI 10.2514/3.11132 PG 6 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600010 ER PT J AU MAVRIPLIS, DJ AF MAVRIPLIS, DJ TI 3-DIMENSIONAL UNSTRUCTURED MULTIGRID FOR THE EULER EQUATIONS SO AIAA JOURNAL LA English DT Article AB The three-dimensional Euler equations are solved on unstructured tetrahedral meshes using a multigrid strategy. The driving algorithm consists of an explicit vertex-based finite element scheme, which employs an edge-based data structure to assemble the residuals. The multigrid approach employs a sequence of independently generated coarse and fine meshes to accelerate the convergence to steady state of the fine grid solution. Variables, residuals, and corrections are passed back and forth between the various grids of the sequence using linear interpolation. The addresses and weights for interpolation are determined in a preprocessing stage using an efficient graph traversal algorithm. The preprocessing operation is shown to require a negligible fraction of the CPU time required by the overall solution procedure, whereas gains in overall solution efficiencies greater than an order of magnitude are demonstrated on meshes containing up to 350,000 vertices. Solutions using globally regenerated fine meshes as well as adaptively refined meshes are given. RP MAVRIPLIS, DJ (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,MS 132C,HAMPTON,VA 23665, USA. NR 20 TC 42 Z9 46 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1753 EP 1761 DI 10.2514/3.11133 PG 9 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600011 ER PT J AU DOGRA, VK WILMOTH, RG MOSS, JN AF DOGRA, VK WILMOTH, RG MOSS, JN TI AEROTHERMODYNAMICS OF A 1.6-METER-DIAMETER SPHERE IN HYPERSONIC RAREFIED FLOW SO AIAA JOURNAL LA English DT Article AB Results of a numerical study using the direct simulation Monte Carlo method are presented for hypersonic rarefied flow about a 1.6-m-diam sphere. The flow conditions considered are those experienced by a typical satellite in orbit or by a space vehicle during entry. The altitude range considered is that from 90 to 200 km, which encompasses the near continuum, transitional, and free-molecular flow regimes. A freestream velocity of 7.5 km/s is assumed in the simulations. The results show that transitional effects are significant at all altitudes below 200 km, but at 200 km the flow about the sphere attains the free-molecular limit. Very little chemical activity is present above 120 km. Both the stagnation point heat transfer and the sphere drag approach their respective free molecule values at 200 km. Results highlight the thermal and chemical nonequilibrium nature of the flowfield. Nonequilibrium effects on the surface heating and body drag are also investigated. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP DOGRA, VK (reprint author), VIGYAN RES ASSOCIATES INC,HAMPTON,VA 23666, USA. NR 13 TC 12 Z9 12 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1789 EP 1794 DI 10.2514/3.11137 PG 6 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600015 ER PT J AU CHEN, CL HUNG, CM AF CHEN, CL HUNG, CM TI NUMERICAL STUDY OF JUNCTURE FLOWS SO AIAA JOURNAL LA English DT Article ID HORSESHOE VORTEX AB A computational study of laminar/turbulent and subsonic/supersonic horseshoe vortex systems generated by a cylindrical protuberance mounted on a flat plate is presented. Various vortex structures have been predicted and are discussed. For a low subsonic laminar flow, the number of computed vortex arrays increases with Reynolds number (with fixed incoming boundary-layer thickness), in agreement with experimental and previous numerical observations. The relationships among pressure extrema, vorticity, and the singular points in the flow structure on the plane of symmetry over the flat plate are studied. Mach number effects have also been investigated for laminar flow at one Reynolds number. The outermost singular point moves upstream when freestream Mach number increases. The size of the whole vortex structure increases dramatically due to shock-wave/boundary-layer interaction. The computed laminar horseshoe vortex systems start from a saddle point of attachment. In the case of a supersonic turbulent flow at a high Reynolds number, the computed results predict the same features as those indicated by the experimental results, such as the upstream shock-wave/boundary-layer interaction and the classical horseshoe vortex system starting from a saddle point of separation. The calculations provide details of the downstream wake/shock-wave interaction and the near wake tornadolike vortex structure. The overall flow topology is discussed. C1 NASA,AMES RES CTR,COMPUTAT FLUID DYNAM,MOFFETT FIELD,CA 94035. RP CHEN, CL (reprint author), ROCKWELL INT CORP,CTR SCI,DEPT COMPUTAT FLUID DYNAM,THOUSAND OAKS,CA 91360, USA. NR 21 TC 13 Z9 15 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1800 EP 1807 DI 10.2514/3.11139 PG 8 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600017 ER PT J AU KASSEMI, SA OSTRACH, S AF KASSEMI, SA OSTRACH, S TI NATURE OF BUOYANCY-DRIVEN FLOWS IN A REDUCED-GRAVITY ENVIRONMENT SO AIAA JOURNAL LA English DT Article ID CONVECTION; SEGREGATION AB The role of buoyancy-driven convection in reduced-gravity environments has been emphasized. It is shown that for some materials-processing experiments the values of the fundamental dimensionless parameters such as Gr or Ra are shifted from the very large (ground-based values) to moderately large (space-based values). As a consequence, in cases where approximate analytical solutions are desired, the accuracy of the usual asymptotic (boundary-layer) analysis in which infinitely large parametric ranges are assumed is reduced. Approximate analytical techniques for refinement of the asymptotic solutions are identified that will extend the accuracy to the moderately large parametric ranges associated with space-based processing. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. CASE WESTERN RESERVE UNIV,DEPT MECH & AERONAUT ENGN,CLEVELAND,OH 44106. NR 18 TC 7 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1815 EP 1818 DI 10.2514/3.11141 PG 4 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600019 ER PT J AU NOOR, AK PETERS, JM AF NOOR, AK PETERS, JM TI REDUCED BASIS TECHNIQUE FOR CALCULATING SENSITIVITY COEFFICIENTS OF NONLINEAR STRUCTURAL RESPONSE SO AIAA JOURNAL LA English DT Article ID REDUCTION METHODS; DESIGN; SYSTEMS; PLATES AB An efficient reduced basis technique is presented for calculating the sensitivity of nonlinear structural response to variations in the design variables. The structure is discretized by using two-field mixed finite element models. The vector of structural response and its sensitivity coefficients (derivatives with respect to design variables) are each expressed as a linear combination of a small number of basis (or global approximation) vectors. The Bubnov-Galerkin technique is then used to approximate each of the finite element equations governing the response and the sensitivity coefficients by a small number of algebraic equations in the amplitudes of these vectors. The path derivatives (derivatives of the response vector with respect to path parameters; e.g., load parameters) are used as basis vectors for approximating the response. A combination of the path derivatives and their derivatives with respect to the design variables is used for approximating the sensitivity coefficients. The potential of the proposed technique is discussed and its effectiveness is demonstrated by means of numerical examples of laminated composite plates subjected to mechanical and thermal loads. C1 UNIV VIRGINIA,CTR COMPUTAT STRUCT TECHNOL,CHARLOTTESVILLE,VA 22903. RP NOOR, AK (reprint author), NASA,LANGLEY RES CTR,AEROSP STRUCT & APPL MECH,HAMPTON,VA 23665, USA. NR 21 TC 13 Z9 13 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1840 EP 1847 DI 10.2514/3.11145 PG 8 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600023 ER PT J AU BANDYOPADHYAY, PR AF BANDYOPADHYAY, PR TI REYNOLDS-NUMBER DEPENDENCE OF THE FREESTREAM TURBULENCE EFFECTS ON TURBULENT BOUNDARY-LAYERS SO AIAA JOURNAL LA English DT Note ID FREE-STREAM TURBULENCE C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 18 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1992 VL 30 IS 7 BP 1910 EP 1912 DI 10.2514/3.11154 PG 3 WC Engineering, Aerospace SC Engineering GA JC206 UT WOS:A1992JC20600032 ER PT J AU ECKBERG, DL CONVERTINO, VA FRITSCH, JM DOERR, DF AF ECKBERG, DL CONVERTINO, VA FRITSCH, JM DOERR, DF TI REPRODUCIBILITY OF HUMAN VAGAL CAROTID BARORECEPTOR-CARDIAC REFLEX RESPONSES SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Note DE BAROREFLEX; NECK CHAMBER ID HEART-RATE-VARIABILITY; HUMAN SINUS NODE; BLOOD-PRESSURE; BAROREFLEX SENSITIVITY; STIMULATION; MODULATION; MECHANISMS; REST AB Published information on the reproducibility of human baroreflex responses in the absence of interventions is limited. Therefore, we analyzed retrospectively vagally mediated carotid baroreceptor-cardiac reflex responses of 34 healthy young adult volunteers whom we studied twice, 7-10 days apart (all 34 subjects) or 10 wk apart (8 subjects). We delivered a sequence of neck pressure changes during held expiration: A computer-driven bellows initially raised pressure to approximately 40 mmHg for five heart beats, and then reduced pressure in a stepwise series of R-wave-triggered 15-mmHg decrements to about -65 mmHg. R-R interval changes were plotted as functions of the carotid distending (systolic less neck) pressure occurring within each interval. Each experimental session yielded one stimulus-response relation, which comprised the average of seven separate trials. Six measures were derived from these relations: minimum, maximum, and range of R-R intervals; maximum slope; and operational point [(R-R interval shortening/R-R interval range) x 100%]. Linear regression correlation coefficients for measurements made on two occasions were all highly significant (range: 0.64-0.99). Our results indicate that human vagally mediated carotid baroreceptor-cardiac reflex responses, studied serially under exacting experimental conditions, are highly reproducible. C1 HUNTER HOLMES MCGUIRE VET ADM MED CTR,DEPT PHYSIOL,RICHMOND,VA 23249. NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. RP ECKBERG, DL (reprint author), HUNTER HOLMES MCGUIRE VET ADM MED CTR,DEPT MED,1201 BROAD ROCK RD,RICHMOND,VA 23249, USA. FU NHLBI NIH HHS [HL-22296] NR 33 TC 42 Z9 42 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD JUL PY 1992 VL 263 IS 1 BP R215 EP R220 PN 2 PG 6 WC Physiology SC Physiology GA JF321 UT WOS:A1992JF32100073 PM 1636791 ER PT J AU RYER, CH OLLA, BL AF RYER, CH OLLA, BL TI SOCIAL MECHANISMS FACILITATING EXPLOITATION OF SPATIALLY-VARIABLE EPHEMERAL FOOD PATCHES IN A PELAGIC MARINE FISH SO ANIMAL BEHAVIOUR LA English DT Article ID JUVENILE WALLEYE POLLOCK; THERAGRA-CHALCOGRAMMA; INFORMATION-TRANSFER; BLUNTNOSE MINNOWS; PREDATOR PRESENCE; SHOAL SIZE; ALASKA RP RYER, CH (reprint author), NOAA,NATL MARINE FISHERIES SERV,HATFIELD MARINE SCI CTR,NW & ALASKA FISHERIES CTR,NEWPORT,OR 97365, USA. NR 20 TC 61 Z9 61 U1 0 U2 5 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0003-3472 J9 ANIM BEHAV JI Anim. Behav. PD JUL PY 1992 VL 44 IS 1 BP 69 EP 74 DI 10.1016/S0003-3472(05)80756-0 PG 6 WC Behavioral Sciences; Zoology SC Behavioral Sciences; Zoology GA JF046 UT WOS:A1992JF04600009 ER PT J AU SULZNER, M STANLOTTER, H HOCHSTEIN, LI AF SULZNER, M STANLOTTER, H HOCHSTEIN, LI TI NUCLEOTIDE-PROTECTABLE LABELING OF SULFHYDRYL-GROUPS IN SUBUNIT-I OF THE ATPASE FROM HALOBACTERIUM-SACCHAROVORUM SO ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS LA English DT Note ID ARCHAEBACTERIUM SULFOLOBUS-ACIDOCALDARIUS; MEMBRANE-ASSOCIATED ATPASE; ESCHERICHIA-COLI; ALPHA-SUBUNIT; THIOL MODIFICATION; H+-ATPASE; F1 ATPASE; ZEA-MAYS; VACUOLAR; PHOSPHORYLATION C1 UNIV VIENNA,INST MIKROBIOL & GENET,ALTHANSTR 14,A-1090 VIENNA,AUSTRIA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 29 TC 3 Z9 3 U1 2 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0003-9861 J9 ARCH BIOCHEM BIOPHYS JI Arch. Biochem. Biophys. PD JUL PY 1992 VL 296 IS 1 BP 347 EP 349 DI 10.1016/0003-9861(92)90582-H PG 3 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA HY138 UT WOS:A1992HY13800045 PM 1534982 ER PT J AU ARCENEAUX, TW AF ARCENEAUX, TW TI RETROFITTING THE HEATING-SYSTEM FOR NASA SPACE-SHUTTLE ENGINE TEST FACILITY SO ASHRAE JOURNAL-AMERICAN SOCIETY OF HEATING REFRIGERATING AND AIR-CONDITIONING ENGINEERS LA English DT Article RP ARCENEAUX, TW (reprint author), NASA,JOHN C STENNIS SPACE CTR,DIV FACILITIES ENGN,BAY ST LOUIS,MI, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC HEAT REFRIG AIR- CONDITIONING ENG INC PI ATLANTA PA 1791 TULLIE CIRCLE NE, ATLANTA, GA 30329 SN 0001-2491 J9 ASHRAE J JI ASHRAE J.-Am. Soc. Heat Refrig. Air-Cond. Eng. PD JUL PY 1992 VL 34 IS 7 BP 24 EP 27 PG 4 WC Thermodynamics; Construction & Building Technology; Engineering, Mechanical SC Thermodynamics; Construction & Building Technology; Engineering GA JC661 UT WOS:A1992JC66100012 ER PT J AU HUTCHINGS, JB NEFF, SG AF HUTCHINGS, JB NEFF, SG TI OPTICAL IMAGING OF QSOS WITH 0.5 ARCSEC RESOLUTION SO ASTRONOMICAL JOURNAL LA English DT Article ID NUCLEAR SPECTROSCOPY; UNDERLYING GALAXIES; HOST GALAXIES; RADIO-LOUD; QUASARS; MORPHOLOGY; EMISSION AB We present optical imaging data on 28 low redshift QSOs with 0.5 arcsec resolution. The group includes a range of radio and IR luminosities. The high-resolution data reveal significant new morphological information on 16 objects, and yield good luminosity profiles on all of them. Most objects appear to have R1/4 law or peculiar luminosity profiles. The QSOs are almost all found to be in merging or interacting galaxies, most of them with a smaller companion. The observed structural details appear to be similar to lower luminosity AGN at low redshift. There are a few unexplained features such as "jets" near the nucleus. Detailed descriptions are given of all objects. We also describe new high-resolution radio observations of a few of the QSOs. C1 NATL RES COUNCIL CANADA,DOMINION ASTROPHYS OBSERV,VICTORIA V8X 4M6,BC,CANADA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 31 TC 124 Z9 124 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1992 VL 104 IS 1 BP 1 EP 14 DI 10.1086/116216 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA232 UT WOS:A1992JA23200001 ER PT J AU CARINI, MT MILLER, HR NOBLE, JC GOODRICH, BD AF CARINI, MT MILLER, HR NOBLE, JC GOODRICH, BD TI THE TIMESCALES OF THE OPTICAL VARIABILITY OF BLAZARS .3. OJ 287 AND BL LACERTAE SO ASTRONOMICAL JOURNAL LA English DT Article ID SPACED DATA AB The BL Lacertae objects OJ 287 and BL Lac have been photometrically monitored in an effort to study the nature of optical variations which may occur on timescales ranging from years to less than a day. The results of ten years of photometric monitoring of these two objects show variations which are consistent with those reported by other authors. No strong dependence of color with source brightness was detected, although both sources exhibited a weak tendency to be bluer when brighter. Microvariability was observed for both objects; variations as large as 0.1 mag/hr were observed for BL Lac and changes as large as 0.08 mag/hr were observed for OJ 287. No evidence for a periodicity was found in the observed variations of either object. C1 NASA,GODDARD SPACE FLIGHT CTR,IUE OBSERV,SCI PROGR COMP SCI CORP,GREENBELT,MD 20771. GEORGIA STATE UNIV,DEPT PHYS & ASTRON,ATLANTA,GA 30303. NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. NR 51 TC 103 Z9 104 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1992 VL 104 IS 1 BP 15 EP 27 DI 10.1086/116217 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA232 UT WOS:A1992JA23200002 ER PT J AU WALLER, WH GURWELL, M TAMURA, M AF WALLER, WH GURWELL, M TAMURA, M TI CIRCUMNUCLEAR PILEUPS OF DUST AND GAS IN M82 SO ASTRONOMICAL JOURNAL LA English DT Article ID H-II REGIONS; FAR-INFRARED SPECTROSCOPY; STAR FORMATION; MOLECULAR CLOUDS; STANDARD STARS; EMISSION-LINE; GALAXY M82; NUCLEUS; EXTINCTION; STARBURST AB Red Ha and R-band CCD images of the starburst galaxy M82 are compared with corresponding near-infrared [S III] and I-band images and with a smaller Br-gamma infrared-array image of the central 500 pc. Enhancements in the continuum-subtracted [S III]/H-alpha-flux ratio are evident along a approximately kpc-long arc that includes the nuclear "dust lanes" visible at Ha as well as two especially enhanced regions on opposite sides of the bursting nucleus. If interpreted as the consequences of reddening by dust, the [S III]/H-alpha-flux enhancements indicate the presence of obscured ionized gas, much of which is distributed immediately beyond the nuclear 1 kpc. Further support for the reddening interpretation is found in the distributions of (R - I) colors in the disk and Br-gamma/H-alpha-flux ratios near the nucleus. The arc-like morphology of the obscuration as well as the strong peripheral extinction can be explained by invoking a kpc-size circumnuclear annulus of gas and entrained dust that is highly inclined to the line of sight. Comparisons with other tracers of interstellar matter are made in an effort to test the proposed scenario. Although some of the comparisons are ambiguous, most of them reinforce the picture of a circumnuclear pileup-probably toroidal in form-which is dynamically linked to the central (bilobal) starburst and which is now collimating the subsequent eruptions and emergent radiation. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. NR 91 TC 26 Z9 26 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1992 VL 104 IS 1 BP 63 EP & DI 10.1086/116221 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA232 UT WOS:A1992JA23200006 ER PT J AU ARMSTRONG, JT MOZURKEWICH, D VIVEKANAND, M SIMON, RS DENISON, CS JOHNSTON, KJ PAN, XP SHAO, M COLAVITA, MM AF ARMSTRONG, JT MOZURKEWICH, D VIVEKANAND, M SIMON, RS DENISON, CS JOHNSTON, KJ PAN, XP SHAO, M COLAVITA, MM TI THE ORBIT OF ALPHA EQUULEI MEASURED WITH LONG-BASE-LINE OPTICAL INTERFEROMETRY - COMPONENT MASSES, SPECTRAL TYPES, AND EVOLUTIONARY STATE SO ASTRONOMICAL JOURNAL LA English DT Article ID UBVRI PHOTOMETRY; STARS AB We present the orbit of the double-lined spectroscopic binary alpha-Equulei, and masses and absolute magnitudes for its components, from observations with the Mark III Optical Interferometer. Our orbit with the spectroscopic results of Rosvick & Scarfe [MNRAS, 252, 68 (1991)] imply masses and 1-sigma or uncertainties of 2.13 +/- 0.29 M. for the G primary and 1.86 +/- 0.21 M. for the A secondary. The magnitude differences that we measure at the four observed wavelengths are consistent with a G5 III primary and an A5 V secondary, with an uncertainty of about 1.5 subtypes. We compare the masses, magnitude differences, and absolute magnitudes determined here with the evolutionary models of VandenBerg [ApJS, 58, 711 (1985)] and infer that the metallicity Z=Z.. The masses of the G and A components from the orbital fit agree with the evolutionary masses (2.36-2.75 M. and 2.01-2.14 M., respectively) that fit their derived colors and absolute magnitudes. The best-fit age from the evolutionary model is 0.5-0.65 Gyr. The parallax of the system obtained from combining the spectroscopic and interferometric data, for which the term "orbital parallax" has been suggested, is given by pi(orb)=0".01808+/-0".00076. C1 USN OBSERV, OPT INTERFEROMETER PROJECT, NRL, WASHINGTON, DC 20390 USA. CALTECH, DEPT ASTRON, PASADENA, CA 91125 USA. JET PROP LAB, PASADENA, CA 91109 USA. NR 33 TC 41 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 JUL PY 1992 VL 104 IS 1 BP 241 EP 252 DI 10.1086/116236 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA232 UT WOS:A1992JA23200021 ER PT J AU HANNER, MS VEEDER, GJ TOKUNAGA, AT AF HANNER, MS VEEDER, GJ TOKUNAGA, AT TI THE DUST COMA OF COMET P-GIACOBINI-ZINNER IN THE INFRARED SO ASTRONOMICAL JOURNAL LA English DT Article ID P/GIACOBINI-ZINNER; SPECTROPHOTOMETRY; HALLEY; MODEL; PHOTOMETRY; P/HALLEY; EMISSION; NUCLEUS; GAS AB We present 1-20-mu-m photometry of P/Giacobini-Zinner obtained at the NASA Infrared Telescope Facility, during 1985 June-September (r= 1.57-1.03 AU). A broad, weak 10-mu-m silicate emission feature was detected on August 26.6; a similar weak emission feature could have been hidden in the broadband photometry on other dates. The total scattering and emitting cross section of dust in the inner coma was similar to that in other short-period comets, but a factor of 10 (r=1.56 AU) to 100 (r=1.03 AU) lower than the amount of dust in Comet Halley. The thermal emission continuum can be fit with models weighted toward either small or large absorbing grains. The dust production rate near perihelion was approximately 10(5) g/s (small-grain model) to approximately 10(6) g/s (large-grain model). The corresponding dust/gas mass ratio on August 26 was approximately 0.1-1. A silicate-rich heterogeneous grain model with an excess of large particles is compatible with the observed spectrum of Giacobini-Zinner on August 26. Thus, weak or absent silicate emission does not necessarily imply an absence of silicates in the dust, although the abundance of silicate particles less-than-or-equal-to 1-mu-m radius must have been lower than in Comet Halley. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP HANNER, MS (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 47 TC 23 Z9 23 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1992 VL 104 IS 1 BP 386 EP 393 DI 10.1086/116245 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JA232 UT WOS:A1992JA23200030 PM 11537742 ER PT J AU ANDERSSON, BG ROGER, RS WANNIER, PG AF ANDERSSON, BG ROGER, RS WANNIER, PG TI WARM NEUTRAL HALOS AROUND MOLECULAR CLOUDS .4. H-I AND CONTINUUM - APERTURE SYNTHESIS OBSERVATIONS TOWARDS THE MOLECULAR CLOUD B5 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE INTERSTELLAR MEDIUM, CLOUDS, B5; INTERSTELLAR MEDIUM, KINEMATICS AND DYNAMICS OF; RADIO LINES, 21-CM; RADIO CONTINUUM ID GALACTIC-PLANE SURVEY; PHYSICAL CONDITIONS; DARK CLOUDS; BARNARD-5; MODELS; FIELD AB We present aperture synthesis observations of H I (21 cm) line radiation and continuum emission at 408 and 1420 MHz towards a field centered on the molecular cloud B5. The H I emission shows an extended atomic halo around the molecular cloud. The opacity of the halo is derived using H I absorption toward several background sources and a simple source model is presented. The model indicates that the halo is not gravitationally bound to the molecular cloud and that it is in fact expanding away from it. Approximately 350 M. is contained in the H I halo. Flux densities and spectral indices for the sources detected in both of the continuum bands are given. C1 GOTHENBURG UNIV, S-41124 GOTHENBURG, SWEDEN. DOMINION RADIO ASTROPHYS OBSERV, PENTICTON V2A 6K3, BC, CANADA. RP ANDERSSON, BG (reprint author), JET PROP LAB, MAIL STOP 169-506, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 37 TC 21 Z9 21 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 1992 VL 260 IS 1-2 BP 355 EP 369 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JE834 UT WOS:A1992JE83400043 ER PT J AU CHIU, HY PATERNO, L AF CHIU, HY PATERNO, L TI THE MAINTENANCE OF THE SUNS DIFFERENTIAL ROTATION AND ITS TEMPORAL VARIATIONS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE SUN; ROTATION ID MOTIONS AB We use the horizontal momentum balance equation to infer the strength of the meridional circulation (MC) and Reynolds stresses (RS) at the Sun's surface from the observed properties of the differential rotation (DR). Both MC and RS are important for maintaining the equatorial acceleration. The results indicate that the average value of MC is about 1.1 m s-1, with circulation directed towards the poles in both the hemispheres, and the average value of RS is 3.6 10(7) cm2 s-2, with transport of angular momentum directed towards the equator in both hemispheres, this latter in good agreement with observations. With the above values of MC and RS, we integrate the momentum equation in time, starting from a state of rigid rotation, to investigate the competitive role of MC and RS in producing the presently observed average DR. Our results show that DR is consistent with observations only if both MC and RS have opposite effects, with the strengths given above, in order to balance the viscous torque. Assuming that RS and MC are periodic functions of time, which is observed in the RS case, we also obtained the observed yearly variations of the equatorial angular velocity omega(0). The results show that the simulated time behaviour of omega(0) is compatible with observations. C1 UNIV CATANIA, IST ASTRON, CITTA UNIV, VIALE A DORIA 6, I-95125 CATANIA, ITALY. UDR CATANIA, OSSERV ASTROFIS CATANIA, CNR, GRP NAZL ASTRON, I-95125 CATANIA, ITALY. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 1992 VL 260 IS 1-2 BP 441 EP 446 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JE834 UT WOS:A1992JE83400052 ER PT J AU HOUGH, DH READHEAD, ACS WOOD, DA FELDMEIER, JJ AF HOUGH, DH READHEAD, ACS WOOD, DA FELDMEIER, JJ TI 3-EPOCH VLBI OBSERVATIONS OF THE NUCLEUS IN THE LOBE-DOMINATED QUASAR-3C-334 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, JETS; QUASARS, INDIVIDUAL (3C-334); TECHNIQUES, INTERFEROMETRIC ID RADIO-SOURCES; SUPERLUMINAL MOTION; COMPLETE SAMPLE; QUASAR; STATISTICS; GALAXIES; 3C-245; JETS AB We have observed the nucleus of the lobe-dominated quasar 3C 334 with VLBI at three epochs spanning 7 yr. We report possible superluminal motion with apparent transverse velocity approximately 1.6h-1c (H0 = 100h km s-1 Mpc-1, q0 = 0.5), with an upper limit of approximately 3h-1c. This is the third lobe-dominated quasar confirmed or suspected to be superluminal in our complete flux density-limited sample of these objects, and the sixth including other surveys. This result continues the trend for lobe-dominated quasars to have lower superluminal speeds than core-dominated quasars. We discuss these results within the framework of relativistic beaming models and unification hypotheses. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. RP HOUGH, DH (reprint author), TRINITY UNIV,DEPT PHYS,SAN ANTONIO,TX 78212, USA. NR 39 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1992 VL 393 IS 1 BP 81 EP 86 DI 10.1086/171486 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ510 UT WOS:A1992HZ51000006 ER PT J AU CLAVEL, J NANDRA, K MAKINO, F POUNDS, KA REICHERT, GA URRY, CM WAMSTEKER, W PERACAULABOSCH, M STEWART, GC OTANI, C AF CLAVEL, J NANDRA, K MAKINO, F POUNDS, KA REICHERT, GA URRY, CM WAMSTEKER, W PERACAULABOSCH, M STEWART, GC OTANI, C TI CORRELATED HARD X-RAY AND ULTRAVIOLET VARIABILITY IN NGC-5548 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-5548); GALAXIES, SEYFERT; ULTRAVIOLET, GALAXIES; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; EMISSION-LINE REGION; THIN ACCRETION DISKS; CONTINUUM EMISSION; OUTER REGIONS; QUASARS; IUE; NGC-4151; GALAXIES; GINGA AB We present the result of a series of contemporaneous (within one day) hard X-ray (Ginga) and ultraviolet (IUE) observations of the Seyfert I galaxy NGC 5548. Nine of these observations were carried out over a period of 51 days in 1990 May-July, and two in 1989. An additional simultaneous IUE-EXOSAT observation obtained on 1984 May 21 is also analyzed. In 1989-1990, the 1350 angstrom continuum and 2-10 keV flux both varied by a factor 2.6 in a highly correlated (at better than the 99% confidence level) fashion. Adding the single 1984 data point significantly weakens the correlation, since the UV flux was 3.5 times larger then than its average 1990 value, while the X-ray flux was only 70% higher. In 1990 the UV and X-ray flux variations appear to be simultaneous to within a few (less-than-or-equal-to 6) days. These results, together with the simultaneity of the variations at 5000 and 1350 angstrom, are incompatible with the standard geometrically thin accretion disk model. To salvage the disk model, one must postulate the existence of at least two continuum emission components in the UV-optical regime. The first one arises from thermal reprocessing of the X-ray impinging on and absorbed by the disk, while the other represents the thermal emission generated by viscous processes inside the disk itself. In this scheme, the reprocessed component varies in phase with the hard X-rays and accounts for the bulk of the UV emission when NGC 5548 is in a low to intermediate state of brightness, while larger amplitude variations are driven by a change in the amount of gravitational energy released locally inside the disk. The thermal reprocessing region extends to at least 200 Schwarzschild radii, much further out than the UV-emitting region in a standard disk without reprocessing. Since the relationship between the UV and the X-ray source in NGC 5548 is phenomenologically identical to that in NGC 4151, this scheme may be applicable to Seyfert galaxies as a class. C1 ISAS,SAGAMIHARA,KANAGAWA 229,JAPAN. ESCOLA TECN SUPER ENGN,DEPT MATEMAT,E-08028 BARCELONA,SPAIN. UNIV LEICESTER,DEPT PHYS & ASTRON,LEICESTER LE1 7RH,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. EUROPEAN SPACE AGCY,IUE OBSERV,E-28080 MADRID,SPAIN. RP CLAVEL, J (reprint author), EUROPEAN SPACE TECHNOL CTR,ISO OBSERV,CODE SAI,POSTBUS 299,2200 AG NOORDWIJK,NETHERLANDS. RI Peracaula, Marta/L-9390-2013; Urry, Claudia/G-7381-2011; Otani, Chiko/A-6510-2016; OI Urry, Claudia/0000-0002-0745-9792; Peracaula, Marta/0000-0003-0871-6583 NR 54 TC 127 Z9 127 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1992 VL 393 IS 1 BP 113 EP 125 DI 10.1086/171490 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ510 UT WOS:A1992HZ51000010 ER PT J AU HOLLIS, JM OLIVERSEN, RJ WAGNER, RM FEIBELMAN, WA AF HOLLIS, JM OLIVERSEN, RJ WAGNER, RM FEIBELMAN, WA TI THE 0623+71 BOW SHOCK NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE H-II REGIONS; ISM, INDIVIDUAL (0623 + 71); NOVAE, CATACLYSMIC VARIABLES; SHOCK WAVES ID PLANETARY-NEBULAE; WAVE THEORY; EMISSION; EVOLUTION; BINARIES; BUBBLES AB We present deep radio continuum and deep narrow-band optical emission-line images showing the cataclysmic variable 0623 + 71 engulfed in a bow shock morphology nebula. The limb-brightened H-alpha lambda-6563, [N II] lambda-6584, and 6 cm radio continuum emission regions define the global nebular morphology, extending to much greater spatial distances than the apex-confined [O III] lambda-5007; these morphologies are consistent with shock excitation. We also present complementary spectroscopy (3400-7400 angstrom) for the apex and east and west limbs of the bow shock, yielding diagnostic emission-line parameters which also indicate shock excitation. Moreover, archival IUE spectra (1200-2000 angstrom) suggest the cataclysmic variable 0623 + 71 may be in a standstill phase. We derive a mass-loss rate of approximately 1.4 x 10(-11) M. yr-1 and a total nebular mass of approximately 2.4 x 10(-3) M.. We discuss the data presented here in the context of a binary system with a stellar wind moving supersonically with respect to the interstellar medium to give rise to the bow shock morphology. C1 OHIO STATE UNIV,LOWELL OBSERV,DEPT ASTRON,FLAGSTAFF,AZ 86001. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HOLLIS, JM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,CODE 930,GREENBELT,MD 20771, USA. NR 33 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1992 VL 393 IS 1 BP 217 EP & DI 10.1086/171499 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ510 UT WOS:A1992HZ51000019 ER PT J AU LINSKY, JL DRAKE, SA BASTIAN, TS AF LINSKY, JL DRAKE, SA BASTIAN, TS TI RADIO-EMISSION FROM CHEMICALLY PECULIAR STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE RADIO CONTINUUM, STARS; STARS, CHEMICALLY PECULIAR ID CONTROLLED CIRCUMSTELLAR MATTER; HELIUM-STRONG STARS; AP-STARS; MAGNETIC-FIELDS; MERIDIONAL CIRCULATION; EFFECTIVE TEMPERATURES; ROTATING STARS; STELLAR WINDS; WEAK STARS; RADIATION AB We have extended the initial survey of radio emission from magnetic Bp-Ap stars by Drake et al. in five subsequent VLA2 observing runs. A total of 16 sources have been detected at 6 cm out of 61 observed, giving a detection rate of 26%. Of these stars, three are also detected at 2 cm, four at 3.6 cm, and five at 20 cm. In addition to the three He-strong and two He-weak/Si-strong stars previously reported as radio sources, we have detected 11 new stars as radio sources with spectral types B5-A0 that are He-weak and Si-strong. We have not yet detected any of the classical (SrCrEu-type) Ap stars despite many attempts. We find a wide range of high 6 cm radio luminosities for the detected stars, with log L6 = 14.7-17.9. The early-B He-strong stars are on average 20 times more radio luminous than the late-B He-weak stars and 1000 times more luminous than theta-Aurigae, the star with both the lowest radio luminosity and the lowest effective temperature. Multifrequency observations indicate flat spectra in all cases. Four stars have a detectable degree of circular polarization at one or more frequencies. We believe that the radio-emitting CP (chemically peculiar) stars form a distinct class of radio stars that differs from both the hot star wind sources and the active late-type stars. For the detected CP stars we find that L6 is-proportional-to M0.5 B(rms), where M is the mass-loss rate and B(rms) is the rms value of the observed longitudinal field strength. We show that all of the observed properties of radio emission from these stars may be understood in terms of optically thick gyrosynchrotron emission from a nonthermal distribution of electrons. We propose a model in which the electrons are produced in current sheets forming 10-20 radii from the star. In this model the electrons travel along magnetic fields to smaller radii and higher magnetic latitudes where they mirror and radiate microwave radiation. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS SCI ARCHIVE RES CTR,GREENBELT,MD 20771. UNIV COLORADO,BOULDER,CO 80309. NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. RP LINSKY, JL (reprint author), NATL INST STAND & TECHNOL,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309, USA. NR 60 TC 58 Z9 58 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1992 VL 393 IS 1 BP 341 EP 356 DI 10.1086/171509 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ510 UT WOS:A1992HZ51000029 ER PT J AU CARLSON, BE LACIS, AA ROSSOW, WB AF CARLSON, BE LACIS, AA ROSSOW, WB TI ORTHO-PARA-HYDROGEN EQUILIBRATION ON JUPITER SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; PLANETS AND SATELLITES, INDIVIDUAL (JUPITER) ID INFRARED OBSERVATIONS; JOVIAN PLANETS; ATMOSPHERE; VOYAGER; ABSORPTION; ABUNDANCE; SYSTEM; H-2; NH3 AB Voyager IRIS observations have revealed that the Jovian para-hydrogen fraction is not in thermodynamic equilibrium near the NH3 cloud top. This implies that a vertical gradient exists between the high-temperature equilibrium value of 0.25 at depth and the cloud top values measured by Voyager. We use an anisotropic multiple-scattering radiative transfer model to retrieve the height-dependent para-hydrogen profile. While the centers of the S(0) and S(1) hydrogen lines originate near the tropopause (i.e., above the NH3 cloud top), emission in the wing of the S(0) line originates within the NH3 cloud layer. The inclusion of spectrally dependent multiple-scattering calculations allows us to use the variation in gaseous absorption strength from the line center to the wing to retrieve the height-dependent para-fraction profile. We find that a vertical correlation exists between the location of the para-hydrogen gradient and the NH3 cloud, strongly suggesting that paramagnetic conversion on NH3 cloud particle surfaces is the dominant equilibration mechanism. Below the NH3 cloud layer, the para fraction is constant with depth and equal to the high-temperature equilibrium value of 0.25. The degree of cloud-top equilibration appears to depend on the optical depth of the NH3 cloud layer. Belt-zone differences exist in the degree of equilibration. Larger, more nearly equilibrated para-fraction values are found in zones. Belt-zone differences in the strength of the para-hydrogen gradient also exist. In belts, the gradient is clearly associated with the location of the NH3 cloud, and equilibration begins at cloud base, almost-equal-to 0.5-0.55 bar. In zones, "equilibration" does not begin until 0.4 bar, roughly 0.1 bar above the NH3 cloud base. This difference is most likely a consequence of the advection of low para-fraction values from depth. RP CARLSON, BE (reprint author), GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Lacis, Andrew/D-4658-2012; Carlson, Barbara/D-8319-2012; Rossow, William/F-3138-2015 NR 31 TC 17 Z9 17 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1992 VL 393 IS 1 BP 357 EP 372 DI 10.1086/171510 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ510 UT WOS:A1992HZ51000030 ER PT J AU MACLOW, MM ELITZUR, M AF MACLOW, MM ELITZUR, M TI WATER MASERS IN W49N - THE YOUNGEST STELLAR JET SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; MASERS; STARS, FORMATION ID INTERSTELLAR BUBBLES; H2O SOURCES; OUTFLOWS; CLOUDS; STARS AB Observations by Gwinn, Moran, and Reid of the proper motions of water masers in W49N show that they have an elongated distribution expanding from a common center. Features with high space velocity only occur far from the center, while low-velocity features occur at all distances. We propose that water masers in star-forming regions occur in expanding shells swept up by high-velocity winds from young, massive stars during the early phases of the expansion. In W49N, confinement of the bubble by a density distribution with an axial cavity can explain both the velocity field and the shape of the maser distribution. We present a fully dynamical calculation of the expanding bubble which provides a satisfactory fit for the observations and suggests that this system is only approximately 250 yr old. Thus these observations may show the very first stages of the formation of a jet from a young stellar object. C1 UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. UNIV KENTUCKY, DEPT PHYS & ASTRON, LEXINGTON, KY 40506 USA. RP MACLOW, MM (reprint author), NASA, AMES RES CTR, DIV SPACE SCI, MS 245-3, MOFFETT FIELD, CA 94035 USA. OI Mac Low, Mordecai-Mark/0000-0003-0064-4060 NR 22 TC 13 Z9 13 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1992 VL 393 IS 1 BP L33 EP L36 DI 10.1086/186444 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ513 UT WOS:A1992HZ51300009 ER PT J AU SILK, J SCHRAMM, DN AF SILK, J SCHRAMM, DN TI THE DIFFUSE GAMMA-RAY BACKGROUND, LIGHT-ELEMENT ABUNDANCES, AND SIGNATURES OF EARLY MASSIVE STAR FORMATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS; DIFFUSE RADIATION; EARLY UNIVERSE; GALAXY, ABUNDANCES; GAMMA RAYS, THEORY; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES ID GALACTIC COSMIC-RAYS; LI; RADIATION; NUCLEI; GALAXY AB Spallation synthesis of the observed Population Il beryllium and boron requires a cosmic-ray flux in the early Galaxy that, in an almost model-independent way, implies a potentially observable signature of redshifted pi-0-decay photons in the extragalactic diffuse gamma-ray background. C1 UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,CHICAGO,IL 60637. RP SILK, J (reprint author), UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720, USA. NR 22 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1992 VL 393 IS 1 BP L9 EP L11 DI 10.1086/186438 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ513 UT WOS:A1992HZ51300003 ER PT J AU SAHADE, J BARBA, R KONDO, Y AF SAHADE, J BARBA, R KONDO, Y TI THE ORBITAL PARAMETERS AND THE IUE SPECTRUM OF THE SINGLE-LINED SPECTROSCOPIC BINARY HD-698 SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE BINARIES, SPECTROSCOPIC; CIRCUMSTELLAR MATTER; STARS, INDIVIDUAL (HD-698); ULTRAVIOLET, STARS AB IUE observations of the spectroscopic binary HD 698 show that its continuous spectrum corresponds to that of a B5 III-II object and that, even in the ultraviolet, the object is single-lined. The spectrum displays several sets of lines, all in absorption, where we distinguish features that partake of the orbital motion of the B5 component, lines that suggest the existence of nonthermal sources of energy, and lines that form at the boundary of the circumstellar envelope, part of them being of purely interstellar origin. The circumbinary envelope appears to expand and then starts decelerating before we reach the layer where the resonance doublet of Si IV originates. The "discrete absorptions" that are characteristics of the spectra of early-type stars are present in the spectrum. New values of the orbital period and of the rest of the orbital parameters are determined on the basis of all the available ground-based data. C1 INST ARGENTINO RADIOASTRON,RA-1894 VILLA ELISA,ARGENTINA. NATL UNIV LA PLATA,FAC CIENCIAS ASTRON & GEOFIS,RA-1900 LA PLATA,ARGENTINA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP SAHADE, J (reprint author), OBSERV ASTRON,CC 677,RA-1900 LA PLATA,ARGENTINA. RI Barba, Rodolfo/P-4649-2014 OI Barba, Rodolfo/0000-0003-1086-1579 NR 18 TC 2 Z9 2 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 1992 VL 81 IS 1 BP 303 EP 319 DI 10.1086/191694 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ731 UT WOS:A1992HZ73100012 ER PT J AU SCHAEFER, BE LANDOLT, AU VOGT, N BUCKLEY, D WARNER, B WALKER, AR BOND, HE AF SCHAEFER, BE LANDOLT, AU VOGT, N BUCKLEY, D WARNER, B WALKER, AR BOND, HE TI THE PHOTOMETRIC PERIOD OF THE RECURRENT NOVA T-PYXIDIS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE NOVAE, CATACLYSMIC VARIABLES; STARS, INDIVIDUAL (T-PYXIDIS) ID ORBITAL PERIODS; STARS AB T Pyx is one of four known recurrent novae suspected to be powered by thermonuclear runaways. If the orbital period can be measured with high accuracy before the next eruption, then it may be possible to detect its period change caused by the eruption, which can then be directly related to the mass ejected from the system. This dynamical measurement of an important model parameter is independent of the various uncertainties that plague spectroscopic determinations of the mass loss. This paper presents 1713 photometric measurements from 1966 until 1990. The light curve of T Pyx shows roughly sinusoidal variations with a typical amplitude of 0.09 mag and time scale of 2 hr. Discrete Fourier transforms of data from individual nights and runs reveal a highly significant periodic modulation. We prove this modulation to be coherent only on time scales shorter than from 6 days to under 1 day. The variable period of T Pyx is disappointing since the modulation cannot be accurately tied to the orbital period, so that no pre-eruption orbital period will be available. We measure the modulation period with sufficient accuracy that the daily alias problem is probably solved. Our period for the modulations is 0.07616+/-0.00017 days. We note that other stars have variable photometric periods (possibly related to the superhump phenomenon) which are slightly different from the orbital period. so that we suggest an orbital period of near 0.073 days for T Pyx. C1 LOUISIANA STATE UNIV,BATON ROUGE,LA 70803. CATHOLIC UNIV CHILE,SANTIAGO,CHILE. UNIV CAPE TOWN,CAPE TOWN,SOUTH AFRICA. CERRO TOLOLO INTERAMER OBSERV,LA SERENA,CHILE. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 25 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 1992 VL 81 IS 1 BP 321 EP 333 DI 10.1086/191695 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HZ731 UT WOS:A1992HZ73100013 ER PT J AU HAUSER, J SASTRY, S MEYER, G AF HAUSER, J SASTRY, S MEYER, G TI NONLINEAR CONTROL DESIGN FOR SLIGHTLY NONMINIMUM PHASE SYSTEMS - APPLICATION TO V/STOL AIRCRAFT SO AUTOMATICA LA English DT Article DE AEROSPACE CONTROL; NONLINEAR CONTROL SYSTEMS; LINEARIZATION TECHNIQUES; NONLINEAR NONMINIMUM PHASE SYSTEMS ID FEEDBACK AB There has been a great deal of excitement recently over the development of a theory for explicitly linearizing the input-output response of a nonlinear system using state feedback. One shortcoming of this theory is the inability to deal with non-minimum phase nonlinear systems. Highly maneuverable jet aircraft, such as the V/STOL Harrier, belong to an important class of a slightly non-minimum phase nonlinear systems. The non-minimum phase character of aircraft is a result of the small body forces that are produced in the process of generating body moments. In this paper, we show that, while straightforward application of the linearization theory to a non-minimum phase system results in a system with a linear input-output response but unstable internal dynamics, designing a feedback control based on a minimum phase approximation to the true system results in a system with desirable properties such as bounded tracking and asymptotic stability. C1 UNIV CALIF BERKELEY,BERKELEY,CA 94720. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HAUSER, J (reprint author), UNIV SO CALIF,DEPT EE SYST,LOS ANGELES,CA 90089, USA. NR 18 TC 315 Z9 327 U1 1 U2 14 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0005-1098 J9 AUTOMATICA JI Automatica PD JUL PY 1992 VL 28 IS 4 BP 665 EP 679 DI 10.1016/0005-1098(92)90029-F PG 15 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA JC890 UT WOS:A1992JC89000001 ER PT J AU BAGIAN, JP SCHAFER, LE AF BAGIAN, JP SCHAFER, LE TI COMPARISON OF CURRENT SHUTTLE AND PRE-CHALLENGER FLIGHT SUIT REACH CAPABILITY DURING LAUNCH ACCELERATIONS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Note AB The Challenger accident prompted the creation of a crew escape system which replaced the former Launch Entry Helmet (LEH) ensemble with the current Launch Entry Suit (LES). However, questions were raised regarding the impact of this change on crew reach capability. Our study addressed the question of reach capability and its effect on realistic ground-based training for Space Shuttle missions. Eleven subjects performed reach sweeps in both the LEH and LES suits during 1 and 3 Gx acceleration trials in the Brooks AFB, TX, centrifuge. These reach sweeps were recorded on videotape and subsequently analyzed using a three-dimensional motion analysis system. The ANOVA procedure of the Statistical Analysis System (SAS) program was used to evaluate differences in forward and overhead reach. The results showed that the LES provided less reach capability than its predecessor, the LEH. This study also demonstrated that, since there was no substantial difference between 1 and 3 Gx reach sweeps in the LES, realistic Shuttle launch training may be accomplished in ground-based simulators. C1 NASA,LYNDON B JOHNSON SPACE CTR,ANTHROPOMETRY & BIOMECH LAB,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,ASTRONAUT OFF,HOUSTON,TX 77058. NR 2 TC 1 Z9 1 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD JUL PY 1992 VL 63 IS 7 BP 624 EP 628 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JA489 UT WOS:A1992JA48900013 PM 1616441 ER PT J AU COREY, KA WHEELER, RM AF COREY, KA WHEELER, RM TI GAS-EXCHANGE IN NASA BIOMASS PRODUCTION CHAMBER SO BIOSCIENCE LA English DT Article ID PHOTOSYNTHESIS; WHEAT; CO2; ENVIRONMENTS C1 NASA,BIOL RES & LIFE SUPPORT OFF,KENNEDY SPACE CTR,FL 32899. RP COREY, KA (reprint author), UNIV MASSACHUSETTS,DEPT PLANT & SOIL SCI,AMHERST,MA 01003, USA. NR 35 TC 22 Z9 22 U1 2 U2 2 PU AMER INST BIOLOGICAL SCI PI WASHINGTON PA 1444 EYE ST, NW, STE 200, WASHINGTON, DC 20005 SN 0006-3568 J9 BIOSCIENCE JI Bioscience PD JUL-AUG PY 1992 VL 42 IS 7 BP 503 EP 509 DI 10.2307/1311880 PG 7 WC Biology SC Life Sciences & Biomedicine - Other Topics GA HZ938 UT WOS:A1992HZ93800006 PM 11537404 ER PT J AU KIM, SW BENSON, TJ AF KIM, SW BENSON, TJ TI COMPARISON OF THE SMAC, PISO AND ITERATIVE TIME-ADVANCING SCHEMES FOR UNSTEADY FLOWS SO COMPUTERS & FLUIDS LA English DT Article ID CIRCULAR-CYLINDER; PRESSURE; GRIDS AB Calculations of unsteady flows using a simplified marker-and-cell (SMAC), a pressure-implicit splitting of operators (PISO) and an iterative time-advancing (ITA) scheme are presented. A partial differential equation for incremental pressure is used in each time-advancing scheme. Example flows considered are a polar cavity flow starting from rest and self-sustained oscillatory flows over a circular and a square cylinder. For a large time-step size, the SMAC and ITA schemes are more strongly convergent and yield more accurate results than the PISO sheme. The SMAC scheme is the most efficient computationally. For a small time-step size, the three time-advancing schemes yield equally accurate Strouhal numbers. The capability of each time-advancing scheme to accurately resolve unsteady flows is attributed to the use of a new pressure correction algorithm that can strongly enforce the conservation of mass. The numerical results show that the low frequency of the vortex shedding is caused by the growth time of each vortex shed into the wake region. RP KIM, SW (reprint author), NASA,LEWIS RES CTR,MS 5-11,21000 BROOKPARK ROAD,CLEVELAND,OH 44135, USA. NR 15 TC 44 Z9 44 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD JUL PY 1992 VL 21 IS 3 BP 435 EP 454 DI 10.1016/0045-7930(92)90048-Z PG 20 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA JB257 UT WOS:A1992JB25700009 ER PT J AU LOFGREN, GE LANIER, AB AF LOFGREN, GE LANIER, AB TI DYNAMIC CRYSTALLIZATION EXPERIMENTS ON THE ANGRA-DOS-REIS ACHONDRITIC METEORITE SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article ID OLIVINE AB With the recent discovery of angrite meteorites in the Antarctic collection which clearly have a melt origin the hypothesis that Angra dos Reis (ADOR) itself is a cumulate is being reconsidered. A recent model suggests that ADOR is a porphyry, not a cumulate. Dynamic crystallization experiments have been conducted to determine whether a melt of ADOR composition can crystallize with porphyritic textures at reasonable cooling rates under appropriate heterogeneous nucleation conditions. The nucleation conditions were varied by melting the starting material at different degrees of superheat. Porphyritic textures were produced if nuclei are absent from the melt and embryos are few in number. If some degree of supercooling is developed while the embryos are growing to critical size, the phenocrysts grow with skeletal shapes. Fassaitic pyroxene grows over a large temperature interval before the appearance of kirschsteinite, spinel, and a pyroxferroite-like phase. Alternatively, if the nucleation density is high and irregularity distributed at the beginning of cooling, a granular texture very similar to ADOR is produced. In this case the large fassaites would grow later and poikilitic enclose the early formed granular fassaite. The phases present and their composition depend on the oxygen fugacity, and a complex redox history for ADOR can be inferred. Olivine is not present in quantities compatible with ADOR and kirschsteinite appears to have been stabilized kinetically in the experiments. While a volcanic or hypabyssal history for ADOR is possible based on the experiments, the presence of olivine, particularly as a phenocryst, remains unexplained. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP LOFGREN, GE (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,CODE SN-4,HOUSTON,TX 77058, USA. NR 17 TC 6 Z9 6 U1 1 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD JUL PY 1992 VL 111 IS 2-4 BP 455 EP 466 DI 10.1016/0012-821X(92)90196-3 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JH922 UT WOS:A1992JH92200017 ER PT J AU CWIK, T AF CWIK, T TI PARALLEL DECOMPOSITION METHODS FOR THE SOLUTION OF ELECTROMAGNETIC SCATTERING PROBLEMS SO ELECTROMAGNETICS LA English DT Article AB This paper contains a overview of the methods used in decomposing solutions to scattering problems onto coarse-grained parallel processors. Initially, a short summary of relevant computer architecture is presented as background to the subsequent discussion. After the introduction of a programming model for problem decomposition, specific decompositions of finite difference time domain, finite clement, and integral equation solutions to Maxwell's equations are presented. The paper concludes with an outline of possible software-assisted decomposition methods and a summary. RP CWIK, T (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 6 Z9 6 U1 1 U2 1 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 0272-6343 J9 ELECTROMAGNETICS JI Electromagnetics PD JUL-DEC PY 1992 VL 12 IS 3-4 BP 343 EP 357 DI 10.1080/02726349208908319 PG 15 WC Engineering, Electrical & Electronic SC Engineering GA JQ125 UT WOS:A1992JQ12500007 ER PT J AU BEJDA, AJ PHELAN, BA STUDHOLME, AL AF BEJDA, AJ PHELAN, BA STUDHOLME, AL TI THE EFFECT OF DISSOLVED-OXYGEN ON THE GROWTH OF YOUNG-OF-THE-YEAR WINTER FLOUNDER, PSEUDOPLEURONECTES-AMERICANUS SO ENVIRONMENTAL BIOLOGY OF FISHES LA English DT Note DE HYPOXIA; CHRONIC; CONSTANT; DIURNALLY FLUCTUATING; MORTALITY ID ONCORHYNCHUS-NERKA; REQUIREMENTS; SALMON AB The effects of constant and diurnally fluctuating levels of dissolved oxygen on the growth of young-of-the-year winter flounder, Pseudopleuronectes americanus, were examined under controlled laboratory conditions. Fish were exposed for either 10 or 11 weeks to constant levels of 6.7 (high) and 2.2 (low) mg l-1, and a diurnal fluctuation, ranging from 2.5 to 6.4 mg O2 l-1. Growth rates, calculated for both standard length and weight, for fish exposed to low and diurnally fluctuating levels were significantly reduced (p < 0.001) as compared to those for fish exposed to the high level. Growth rates of fish exposed to the high level were over twice those of fish held under low oxygen conditions. Under fluctuating conditions, fish grew at intermediate rates. Following these exposures, all fish were subsequently held at 7.2 mg O2 l-1 for five weeks. Growth rates increased over two and a half times for fish previously exposed to the low oxygen level and were significantly (p < 0.001) higher than for the other two groups. RP BEJDA, AJ (reprint author), NATL MARINE FISHERIES SERV,NE FISHERIES CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 29 TC 72 Z9 75 U1 3 U2 9 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0378-1909 J9 ENVIRON BIOL FISH JI Environ. Biol. Fishes PD JUL PY 1992 VL 34 IS 3 BP 321 EP 327 DI 10.1007/BF00004780 PG 7 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA JE176 UT WOS:A1992JE17600013 ER PT J AU CHEUNG, BSK MONEY, K HOWARD, I KIRIENKO, N JOHNSON, W LACKNER, J DIZIO, P EVANOFF, J AF CHEUNG, BSK MONEY, K HOWARD, I KIRIENKO, N JOHNSON, W LACKNER, J DIZIO, P EVANOFF, J TI HUMAN OCULAR TORSION DURING PARABOLIC FLIGHTS - AN ANALYSIS WITH SCLERAL SEARCH COIL SO EXPERIMENTAL BRAIN RESEARCH LA English DT Article DE OCULAR TORSION; PARABOLIC FLIGHTS; EYE MOVEMENTS; HUMAN ID OTOLITH FUNCTION; MOTION SICKNESS; EYE-MOVEMENTS; SUSCEPTIBILITY AB Rotation of the eyes about the visual axis is known as ocular torsion. A lateral inclination (a "roll") of the head induces ocular torsion in the opposite direction, a response known as ocular counterrolling. For six subjects, we recorded the static (head still) and dynamic (head in oscillatory roll motion) ocular torsion in normal 1 g condition and also during the microgravity and hypergravity periods of parabolic flight, using the electromagnetic scleral search coil technique. With the head still, the direction and magnitude of torsion that occured in response to microgravity and hypergravity differed substantially from one individual to another, but there was a significant difference in torsional magnitude between the microgravity and hypergravity periods, for all static head positions including the upright position. Under normal 1 g conditions, counterrolling compensated for about 16% of (voluntary) static head roll, while dynamic counterroll was much larger, up to 36% of head roll at 0.55 Hz. With increasing frequency of head oscillation between 0.33 Hz and 0.55 Hz, the gain of counterrolling increased and there was no change in the phase relationship. The gain of dynamic counterroll (in response to voluntary head rolling) was not significantly less in hypogravity, suggesting that on the ground at these frequencies the contribution of gravity and gravity receptors to this reflex is redundant: this reflex is probably driven by the semicircular canals. In some subjects, the torsional displacement in microgravity is accompanied by micro-torsional oscillatory motion. C1 YORK UNIV, INST SPACE & TERR SCI, HUMAN PERFORMANCE SPACE LAB, N YORK M3J 1P3, ONTARIO, CANADA. CANADIAN SPACE AGCY, OTTAWA K1A 0R6, ONTARIO, CANADA. ST MICHAELS HOSP, TORONTO M5B 1W8, ONTARIO, CANADA. BRANDEIS UNIV, ASHTON GRAYBIEL SPATIAL ORIENTATION LAB, WALTHAM, MA 02254 USA. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP CHEUNG, BSK (reprint author), DEF & CIVIL INST ENVIRONM MED, POB 2000, N YORK M3M 3B9, ONTARIO, CANADA. NR 23 TC 13 Z9 13 U1 0 U2 0 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0014-4819 EI 1432-1106 J9 EXP BRAIN RES JI Exp. Brain Res. PD JUL PY 1992 VL 90 IS 1 BP 180 EP 188 PG 9 WC Neurosciences SC Neurosciences & Neurology GA JG262 UT WOS:A1992JG26200021 PM 1521606 ER PT J AU MOFFITT, RB PARRISH, FA AF MOFFITT, RB PARRISH, FA TI AN ASSESSMENT OF THE EXPLOITABLE BIOMASS OF HETEROCARPUS-LAEVIGATUS IN THE MAIN HAWAIIAN-ISLANDS .2. OBSERVATIONS FROM A SUBMERSIBLE SO FISHERY BULLETIN LA English DT Article ID DEEP-WATER SHRIMP; MARIANA ARCHIPELAGO; FISH POPULATIONS; CARIDEAN SHRIMPS; RESOURCE; ENSIFER; LOBSTER AB Five submersible dives were conducted to evaluate the behavior of deepwater shrimp and the relationship of their density to bottom type and trap yield. Differences in behavior of two species of Heterocarpus were observed: H. ensifer tended to group around large anemones and other benthic relief over otherwise flat, sandy bottom and were very active in the presence of a baited container; whereas H. laevigatus were solitary and showed little activity around a baited container. Greater densities of H. laevigatus were observed on volcanic than on coralline substrate, indicating a possible association with this bottom type. Trap catches were regressed against observed H. laevigatus densities yielding an estimate of the catchability coefficient. This coefficient differed from that obtained from a previously conducted Leslie model depletion study. Factors contributing to this difference may include comparing estimates of catchability based on data from different areas, bias in the estimate of catchability based on observed density, and bias in the estimate of catchability from the depletion study. A combined fishing and visual census study is suggested as the best assessment technique. RP MOFFITT, RB (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 28 TC 10 Z9 12 U1 0 U2 1 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1992 VL 90 IS 3 BP 476 EP 482 PG 7 WC Fisheries SC Fisheries GA KB688 UT WOS:A1992KB68800008 ER PT J AU POLOVINA, JJ MITCHUM, GT AF POLOVINA, JJ MITCHUM, GT TI VARIABILITY IN SPINY LOBSTER PANULIRUS-MARGINATUS RECRUITMENT AND SEA-LEVEL IN THE NORTHWESTERN HAWAIIAN-ISLANDS SO FISHERY BULLETIN LA English DT Article ID LARVAL RECRUITMENT; ROCK LOBSTER; FISHERY AB Research and commercial trapping data show variation in recruitment to the fishery for spiny lobster Panulirus marginatus at Maro Reef, relative to Necker Island which is 670 km to the southeast. Recruitment to the fishery at Maro Reef is shown to be highly correlated with the difference in sea level 4 years earlier between French Frigate Shoals and Midway Islands. Geosat altimeter data indicate that the relative sea level between French Frigate Shoals and Midway is an indicator of the strength of the Subtropical Counter Current. Mechanisms linking the Subtropical Counter Current with larval advection and survival are discussed. The sea level index provides a forecast of recruitment 4 years later to the fishery at Maro Reef. C1 UNIV HAWAII,JOINT INST MARINE & ATMOSPHER RES,HONOLULU,HI 96822. UNIV HAWAII,SCH OCEAN & EARTH SCI & TECHNOL,DEPT OCEANOG,HONOLULU,HI 96822. RP POLOVINA, JJ (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 20 TC 26 Z9 26 U1 0 U2 0 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1992 VL 90 IS 3 BP 483 EP 493 PG 11 WC Fisheries SC Fisheries GA KB688 UT WOS:A1992KB68800009 ER PT J AU RALSTON, S TAGAMI, DT AF RALSTON, S TAGAMI, DT TI AN ASSESSMENT OF THE EXPLOITABLE BIOMASS OF HETEROCARPUS-LAEVIGATUS IN THE MAIN HAWAIIAN-ISLANDS .1. TRAPPING SURVEYS, DEPLETION EXPERIMENT, AND LENGTH STRUCTURE SO FISHERY BULLETIN LA English DT Article ID DEEP-WATER SHRIMP; CARIDEAN SHRIMPS; DECAPODA; ENSIFER AB A deepwater trapping survey for Heterocarpus laevigatus was conducted around the main islands of the Hawaiian ArchiPelago to estimate exploitable biomass and potential yield. Stratified sampling by depth zone and island was conducted over a 3-year period to evaluate shrimp catch rates. Catchability of the traps was estimated from a 12-day intensive fishing experiment performed at a small, isolated site in the Kaulakahi Channel; habitat areas were determined by digitizing nautical charts. Results from a Leslie analysis of the depletion experiment showed that H. laevigatus is very susceptible to capture by traps (i.e., catchability q = 9.48 ha/trap-night). There was no evidence of a change in size structure through the course of the experiment. Shrimp catch rates varied greatly by island and depth of capture. Exploitable biomass was greatest in the 460-640 m depth range; negligible amounts of shrimp occurred shallower than 350 m and deeper than 830 m. Catch rates were highest at Niihau and lowest at Oahu. The total exploitable biomass of shrimp in the main Hawaiian Is. was estimated to be 271 MT, a figure substantially less than previously believed. Analysis of multiple size-frequency distributions for each sex showed no evidence of modal size progression. Assuming equilibrium conditions, application of the Wetherall et al. (1987) method to these data resulted in estimates of M/K = 1.01 for female shrimp and 0.74 for males. From these results and estimates of L infinity we calculate that F0.1/M = 0.75 for females and 0.86 for males. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. RP RALSTON, S (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,TIBURON LAB,3150 PARADISE DR,TIBURON,CA 94920, USA. NR 35 TC 8 Z9 8 U1 0 U2 0 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1992 VL 90 IS 3 BP 494 EP 504 PG 11 WC Fisheries SC Fisheries GA KB688 UT WOS:A1992KB68800010 ER PT J AU SOGARD, SM ABLE, KW FAHAY, MP AF SOGARD, SM ABLE, KW FAHAY, MP TI EARLY LIFE-HISTORY OF THE TAUTOG TAUTOGA-ONITIS IN THE MID-ATLANTIC BIGHT SO FISHERY BULLETIN LA English DT Article ID CLUPEA-HARENGUS; SPECIES COMPOSITION; RING DEPOSITION; GROWTH; FISHES; OTOLITHS; EELGRASS; SEASONALITY; INCREMENTS; VALIDATION AB Spawning patterns, larval distribution, and juvenile growth characteristics were examined for tautog Tautoga onitis in New Jersey and the Mid-Atlantic Bight. We analyzed data from plankton surveys (1972-1990) over the continental shelf and in the Great Bay-Mullica River estuarine system. Data on size and abundance of juveniles were derived from throw trap and trawl collections in New Jersey estuaries (1988-89). In addition, we validated the daily deposition of otolith increments and used increment counts to estimate juvenile age and growth patterns. Extensive egg and larval collections indicated that spawning occurs from April through September, with a peak in June and July. Spawning over the continental shelf is concentrated off Long Island and Rhode Island. Based on validated daily increments in sagittal otoliths and the formation of a well-defined settlement mark, tautog larvae spend about 3 weeks in the plankton. Both spawning and settlement occur over a prolonged period, based on otolith back-calculations. Three methods of estimating young-of-the-year growth rates, including length-frequency progressions, otolith age/fish-size comparisons, and direct measurement of growth in caging experiments, indicated an average growth rate of about 0.5 mm/day during the peak midsummer growing season. Length-frequency distributions suggested tautog reach a modal size of about 75 mm SL after their first summer, and 155 mm by the end of their second summer. C1 RUTGERS STATE UNIV,INST MARINE & COASTAL SCI,MARINE FIELD STN,TUCKERTON,NJ 08087. NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES SCI CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732. NR 38 TC 26 Z9 29 U1 1 U2 4 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1992 VL 90 IS 3 BP 529 EP 539 PG 11 WC Fisheries SC Fisheries GA KB688 UT WOS:A1992KB68800013 ER PT J AU LANGEL, RA AF LANGEL, RA TI INTERNATIONAL GEOMAGNETIC REFERENCE FIELD, 1991 REVISION - INTERNATIONAL ASSOCIATION OF GEOMAGNETISM AND AERONOMY (IAGA) DIVISION-V, WORKING GROUP-8 - ANALYSIS OF THE MAIN FIELD AND SECULAR VARIATION SO GEOPHYSICS LA English DT Article ID GENERATION RP LANGEL, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 921,GREENBELT,MD 20771, USA. NR 11 TC 12 Z9 12 U1 0 U2 0 PU SOC EXPLORATION GEOPHYSICISTS PI TULSA PA 8801 S YALE ST, TULSA, OK 74137 SN 0016-8033 J9 GEOPHYSICS JI Geophysics PD JUL PY 1992 VL 57 IS 7 BP 956 EP 959 DI 10.1190/1.1443310 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JD415 UT WOS:A1992JD41500011 ER PT J AU WHEELER, RM AF WHEELER, RM TI GAS-EXCHANGE MEASUREMENTS USING A LARGE, CLOSED PLANT-GROWTH CHAMBER SO HORTSCIENCE LA English DT Article ID ENVIRONMENT; CROP; PHOTOSYNTHESIS; ETHYLENE; AIR RP WHEELER, RM (reprint author), NASA, BIOL OPERAT & LIFE SUPPORT, MAIL CODE MD RES, KENNEDY SPACE CTR, FL 32899 USA. NR 35 TC 37 Z9 39 U1 1 U2 4 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 113 S WEST ST, STE 200, ALEXANDRIA, VA 22314-2851 USA SN 0018-5345 J9 HORTSCIENCE JI Hortscience PD JUL PY 1992 VL 27 IS 7 BP 777 EP 780 PG 4 WC Horticulture SC Agriculture GA JG600 UT WOS:A1992JG60000016 PM 11537623 ER PT J AU BARNET, CD BEEBE, RF CONRATH, BJ AF BARNET, CD BEEBE, RF CONRATH, BJ TI A SEASONAL RADIATIVE DYNAMIC-MODEL OF SATURNS TROPOSPHERE SO ICARUS LA English DT Article ID VOYAGER INFRARED MEASUREMENTS; OUTER PLANETS; PARA-HYDROGEN; ATMOSPHERE; STRATOSPHERE; ABSORPTION; CLIMATE; IMAGES C1 NEW MEXICO STATE UNIV,DEPT ASTRON,LAS CRUCES,NM 88003. RP BARNET, CD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 693 2,GREENBELT,MD 20771, USA. RI Barnet, Christopher/F-5573-2010 NR 34 TC 29 Z9 29 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1992 VL 98 IS 1 BP 94 EP 107 DI 10.1016/0019-1035(92)90210-X PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JF951 UT WOS:A1992JF95100010 ER PT J AU BRYSON, S LEVIT, C AF BRYSON, S LEVIT, C TI THE VIRTUAL WIND-TUNNEL SO IEEE COMPUTER GRAPHICS AND APPLICATIONS LA English DT Article RP BRYSON, S (reprint author), NASA,AMES RES CTR,DIV NUMER AERODYNAM SIMULAT,MS T045-1,MOFFETT FIELD,CA 94035, USA. NR 12 TC 45 Z9 46 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0272-1716 J9 IEEE COMPUT GRAPH JI IEEE Comput. Graph. Appl. PD JUL PY 1992 VL 12 IS 4 BP 25 EP 34 DI 10.1109/38.144824 PG 10 WC Computer Science, Software Engineering SC Computer Science GA JD228 UT WOS:A1992JD22800011 ER PT J AU SHELDON, FT KAVI, KM TAUSWORTHE, RC YU, JT BRETTSCHNEIDER, R EVERETT, WW AF SHELDON, FT KAVI, KM TAUSWORTHE, RC YU, JT BRETTSCHNEIDER, R EVERETT, WW TI RELIABILITY MEASUREMENT - FROM THEORY TO PRACTICE SO IEEE SOFTWARE LA English DT Article C1 UNIV TEXAS,COMP SCI ENGN,ARLINGTON,TX 76019. JET PROP LAB,DIV INFORMAT SYST,PASADENA,CA 91109. AT&T BELL LABS,CTR PROC QUAL,MURRAY HILL,NJ 07974. MOTOROLA INC,MICROPROCESSOR & MEMORY TECHNOL GRP,SCHAUMBURG,IL 60196. RP SHELDON, FT (reprint author), GEN DYNAM CORP,FT WORTH DIV,POB 748,MAIL ZONE 2291,FT WORTH,TX 76101, USA. OI Sheldon, Frederick/0000-0003-1241-2750 NR 9 TC 6 Z9 7 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0740-7459 J9 IEEE SOFTWARE JI IEEE Softw. PD JUL PY 1992 VL 9 IS 4 BP 13 EP 20 DI 10.1109/52.143095 PG 8 WC Computer Science, Software Engineering SC Computer Science GA JA916 UT WOS:A1992JA91600003 ER PT J AU LYU, MR NIKORA, A AF LYU, MR NIKORA, A TI APPLYING RELIABILITY MODELS MORE EFFECTIVELY SO IEEE SOFTWARE LA English DT Article C1 JET PROP LAB,PASADENA,CA 91109. RP LYU, MR (reprint author), UNIV IOWA,DEPT ELECT & COMP ENGN,IOWA CITY,IA 52242, USA. NR 7 TC 31 Z9 33 U1 1 U2 2 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0740-7459 J9 IEEE SOFTWARE JI IEEE Softw. PD JUL PY 1992 VL 9 IS 4 BP 43 EP 52 DI 10.1109/52.143104 PG 10 WC Computer Science, Software Engineering SC Computer Science GA JA916 UT WOS:A1992JA91600007 ER PT J AU JOSHI, SM MAGHAMI, PG AF JOSHI, SM MAGHAMI, PG TI ROBUST DISSIPATIVE COMPENSATORS FOR FLEXIBLE SPACECRAFT CONTROL SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article AB The problem of controller design for flexible spacecraft is addressed. Model-based compensators, which rely on the knowledge of the system parameters to "tune" the state estimator, are first considered, and are shown to have high sensitivity to parameter uncertainties. Three types of dissipative controllers, which use collocated actuators and sensors, are next considered. These controllers guarantee stability in the presence of unmodeled elastic modes and parameter uncertainties. A procedure is given for designing an optimal dissipative dynamic compensator, which can provide better performance while still retaining robust stability. RP JOSHI, SM (reprint author), NASA, LANGLEY RES CTR, MS230, HAMPTON, VA 23665 USA. NR 12 TC 11 Z9 11 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD JUL PY 1992 VL 28 IS 3 BP 768 EP 774 DI 10.1109/7.256297 PG 7 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JM710 UT WOS:A1992JM71000014 ER PT J AU VORPERIAN, V AF VORPERIAN, V TI MODELING THE SWITCH OF PWM CONVERTERS - REPLY SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Letter ID CONDUCTION MODE AB The questions raised by Professor Ben-Yaakov in his correspondence are understandable, and they probably have occurred to other readers who have intuitive conflicts with the average switch model. Such conflicts can easily arise if the expressions and derivations are examined outside the context and approximations of average modeling. The following is an explanation of the points raised by Professor Ben-Yaakov. RP VORPERIAN, V (reprint author), JET PROP LAB,MS 303-300,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 5 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 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD JUL PY 1992 VL 28 IS 3 BP 923 EP 925 PG 3 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JM710 UT WOS:A1992JM71000037 ER PT J AU BAYARD, DS YAM, Y METTLER, E AF BAYARD, DS YAM, Y METTLER, E TI A CRITERION FOR JOINT OPTIMIZATION OF IDENTIFICATION AND ROBUST-CONTROL SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note ID SYSTEMS AB A criterion for system identification is developed which is consistent with the intended use of the fitted model for modern robust control synthesis. Specifically, a joint optimization problem is posed which simultaneously determines the plant model estimate and control design, so as to optimize robust performance over the set of plants consistent with a specified experimental data set. RP BAYARD, DS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 20 TC 39 Z9 39 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD JUL PY 1992 VL 37 IS 7 BP 986 EP 991 DI 10.1109/9.148354 PG 6 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA JE076 UT WOS:A1992JE07600011 ER PT J AU RIGNOT, E CHELLAPPA, R DUBOIS, P AF RIGNOT, E CHELLAPPA, R DUBOIS, P TI UNSUPERVISED SEGMENTATION OF POLARIMETRIC SAR DATA USING THE COVARIANCE-MATRIX SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID FUZZY C-MEANS; RADAR POLARIMETRY; CLASSIFICATION; IMAGES AB This paper presents a method for unsupervised segmentation of polarimetric synthetic aperture radar (SAR) data into classes of homogeneous microwave polarimetric backscatter characteristics. Classes of polarimetric backscatter are selected based on a multidimensional fuzzy clustering of the logarithm of the parameters composing the polarimetric covariance matrix. The clustering procedure uses both polarimetric amplitude and phase information, is adapted to the presence of image speckle, and does not require an arbitrary weighing of the different polarimetric channels; it also provides a partitioning of each data sample used for clustering into multiple clusters. Given the classes of polarimetric backscatter, the entire image is classified using a Maximum A Posteriori polarimetric classifier. Four-look polarimetric SAR complex data of lava flows and of sea ice acquired by the NASA/JPL airborne polarimetric radar (AIRSAR) are segmented using this technique. The results are discussed and compared with those obtained using supervised techniques. C1 UNIV MARYLAND,DEPT ELECT ENGN,COLL PK,MD 20742. UNIV MARYLAND,DEPT COMP SCI,CTR AUTOMAT RES,COLL PK,MD 20742. UNIV MARYLAND,INST ADV COMP STUDIES,COLL PK,MD 20742. RP RIGNOT, E (reprint author), JET PROP LAB,RADAR SCI & ENGN SECT,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 22 TC 60 Z9 62 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1992 VL 30 IS 4 BP 697 EP 705 DI 10.1109/36.158863 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA KW360 UT WOS:A1992KW36000007 ER PT J AU KARAM, MA FUNG, AK LANG, RH CHAUHAN, NS AF KARAM, MA FUNG, AK LANG, RH CHAUHAN, NS TI A MICROWAVE-SCATTERING MODEL FOR LAYERED VEGETATION SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID ELECTROMAGNETIC SCATTERING; FINITE LENGTH; DIELECTRIC CYLINDER; FOREST CANOPIES; WALNUT ORCHARD; BACKSCATTER; SCATTEROMETER; BAND; PROPAGATION; DISKS AB A microwave scattering model has been developed for layered vegetation based on an iterative solution of the radiative transfer equation up to the second order to account for multiple scattering within the canopy and between the ground and the canopy. The model is designed to operate over a wide frequency range for both deciduous and coniferous forest and to account for the branch size distribution, leaf orientation distribution, and branch orientation distribution for each size. The canopy is modeled as a two-layered medium above a rough interface. The upper layer is the crown containing leaves, stems, and branches. The lower layer is the trunk region modeled as randomly positioned cylinders with a preferred orientation distribution above an irregular soil surface. Comparisons of this model with measurements from deciduous and coniferous forests show good agreements at several frequencies for both like and cross polarizations. Major,features of the model needed to realize the agreement include allowance for (1) branch size distribution, (2) second-order effects, and (3) tree component models valid over a wide range of frequencies. C1 GEORGE WASHINGTON UNIV,DEPT ELECT ENGN & COMP SCI,WASHINGTON,DC 20052. NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,GREENBELT,MD 20771. RP KARAM, MA (reprint author), UNIV TEXAS,DEPT ELECT ENGN,WAVE SCATTERING RES CTR,ARLINGTON,TX 76019, USA. NR 36 TC 162 Z9 176 U1 3 U2 19 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1992 VL 30 IS 4 BP 767 EP 784 DI 10.1109/36.158872 PG 18 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA KW360 UT WOS:A1992KW36000016 ER PT J AU WANG, JR CHANG, ATC SHARMA, AK AF WANG, JR CHANG, ATC SHARMA, AK TI ON THE ESTIMATION OF SNOW DEPTH FROM MICROWAVE RADIOMETRIC MEASUREMENTS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID WATER EQUIVALENT; RETRIEVAL AB The multiple-channel microwave radiometric measurements made over Alaska at aircraft (near 90 and 183 GHZ) and satellite (at 37 and 85 GHz) altitudes are used to study the effect of atmospheric absorption on the estimation of snow depth. The estimation is based on the radiative transfer calculations using an early theoretical model of Mie scattering of single size particles [1], [2]. It is shown that the radiometric correction for the effect of atmospheric absorption is important even at 37 GHz for a reliable estimation of snow depth. Under a dry atmosphere of total precipitable water in the range of 0.2-0.4 g/cm2 and based on single-frequency radiometric measurements, the underestimation of snow depth could amount to 50% at 85 GHz and 20-30% at 37 GHz if the effect of atmospheric absorption is not taken into account. The snow depths estimated from the aircraft 90 GHz and 85 GHz satellite measurements are found to be in a reasonable agreement. However, there is a discrepancy in the snow depths estimated from the satellite 37 GHz (at both vertical and horizontal polarizations) and 85 GHz measurements. A more sophisticated model [3] is perhaps needed in the radiative transfer to resolve this discrepancy. In addition, the effects of surface slope and roughness and vegetation cover may also have to be considered to reach a better agreement in the estimation. C1 ST SYST CORP,LANHAM,MD 20706. RP WANG, JR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 18 TC 11 Z9 13 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1992 VL 30 IS 4 BP 785 EP 792 DI 10.1109/36.158873 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA KW360 UT WOS:A1992KW36000017 ER PT J AU FOSTER, JL WINCHESTER, JW DUTTON, EG AF FOSTER, JL WINCHESTER, JW DUTTON, EG TI THE DATE OF SNOW DISAPPEARANCE ON THE ARCTIC TUNDRA AS DETERMINED FROM SATELLITE, METEOROLOGICAL STATION AND RADIOMETRIC INSITU OBSERVATIONS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID NORTHERN-HEMISPHERE; POLLUTION; CLIMATE; ALASKA; HAZE; SOOT AB In this study satellite-derived snow cover maps for sites in Alaska, Canada, Scandinavia, and Siberia were employed to assess the date when snow disappeared on the Arctic tundra and to determine ir the snow has been melting earlier in the spring in more recent years. Results show that for three of the four sites there has been a tendency toward earlier snowmelt during the 1980's. In Alaska, the satellite-derived date of snowmelt was compared to the date of snowmelt as observed at the Barrow meteorological station and a site near Barrow where radiometric in situ measurements were made for the last 5 years. The three data sources complement each other even though the satellite site is located 150 km from Barrow. One mechanism which could cause a trend toward earlier snowmelt in Alaska is the deposition of soot and particulates on the snow surface as a result of Arctic haze. C1 NOAA,ENVIRONM RES LABS,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. FLORIDA STATE UNIV,DEPT OCEANOG,TALLAHASSEE,FL 32306. RP FOSTER, JL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 30 TC 19 Z9 19 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1992 VL 30 IS 4 BP 793 EP 798 DI 10.1109/36.158874 PG 6 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA KW360 UT WOS:A1992KW36000018 ER PT J AU Rignot, E Chellappa, R AF Rignot, Eric Chellappa, Rama TI Segmentation of polarimetric synthetic aperture radar data SO IEEE TRANSACTIONS ON IMAGE PROCESSING LA English DT Article AB A statistical image model is proposed for segmenting polarimetric synthetic aperture radar (SAR) data into regions of homogeneous and similar polarimetric backscatter characteristics. A model for the conditional distribution of the polarimetric complex data is combined with a Markov random field representation for the distribution of the region labels to obtain the posterior distribution. Optimal region labeling of the data is then defined as maximizing the posterior distribution of the region labels given the polarimetric SAR complex data (maximum a posteriori (MAP) estimate). An implementation of the MAP technique on a parallel optimization network is presented. A fast alternative solution is also considered. Two procedures for selecting the characteristics of the regions are then discussed: one is supervised and requires training areas, the other is unsupervised and is based on the multidimensional clustering of the logarithm of the parameters composing the polarimetric covariance matrix of the data. Results using real multilook polarimetric SAR complex data are given to illustrate the potential of the two selection procedures and evaluate the performance of the MAP segmentation technique. The impact of reducing the dimension of the polarimetric measurements on segmentation accuracy is also investigated. The results indicate that dual polarization SAR data may yield almost similar segmentation results as the fully polarimetric SAR data. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Maryland, Dept Elect Engn, Ctr Automat Res, College Pk, MD 20742 USA. Univ Maryland, Inst Adv Comp Studies, College Pk, MD 20742 USA. RP Rignot, E (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 31 TC 75 Z9 82 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855 USA SN 1057-7149 J9 IEEE T IMAGE PROCESS JI IEEE Trans. Image Process. PD JUL PY 1992 VL 1 IS 3 BP 281 EP 300 DI 10.1109/83.148603 PG 20 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA V43US UT WOS:000202960600002 PM 18296163 ER PT J AU GRIFFITHS, DF SWEBY, PK YEE, HC AF GRIFFITHS, DF SWEBY, PK YEE, HC TI ON SPURIOUS ASYMPTOTIC NUMERICAL-SOLUTIONS OF EXPLICIT RUNGE-KUTTA METHODS SO IMA JOURNAL OF NUMERICAL ANALYSIS LA English DT Article ID DIFFERENCE-EQUATIONS; DYNAMICS AB The bifurcation diagram associated with the logistic equation v(n+1) = av(n)(1 - v(n)) is by now well known, as is its equivalence to solving the ordinary differential equation (ODE) u' = alpha-u(1 - u) by the explicit Euler difference scheme. It has also been noted by Iserles that other popular difference schemes may not only exhibit period doubling and chaotic phenomena but also possess spurious fixed points. We investigate, both analytically and computationally, Runge-Kutta schemes applied to the equation u' = f(u), for f(u) = alpha-u(1 - u) and f(u) = alpha-u(1 - u)(b - u), contrasting their behaviour with the explicit Euler scheme. We determine and provide a local analysis of bifurcations to spur-ious fixed points and periodic orbits. In particular we show that these may appear below the linearised stability limit of the scheme, and may consequently lead to erroneous computational results. C1 UNIV READING,DEPT MATH,READING RG6 2AH,BERKS,ENGLAND. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP GRIFFITHS, DF (reprint author), UNIV DUNDEE,DEPT MATH,DUNDEE DD1 4HN,SCOTLAND. NR 19 TC 44 Z9 44 U1 1 U2 1 PU OXFORD UNIV PRESS UNITED KINGDOM PI OXFORD PA WALTON ST JOURNALS DEPT, OXFORD, ENGLAND OX2 6DP SN 0272-4979 J9 IMA J NUMER ANAL JI IMA J. Numer. Anal. PD JUL PY 1992 VL 12 IS 3 BP 319 EP 338 DI 10.1093/imanum/12.3.319 PG 20 WC Mathematics, Applied SC Mathematics GA JJ044 UT WOS:A1992JJ04400001 ER PT J AU MEEHAN, RT NEALE, LS KRAUS, ET STUART, CA SMITH, ML CINTRON, NM SAMS, CF AF MEEHAN, RT NEALE, LS KRAUS, ET STUART, CA SMITH, ML CINTRON, NM SAMS, CF TI ALTERATION IN HUMAN MONONUCLEAR LEUKOCYTES FOLLOWING SPACE-FLIGHT SO IMMUNOLOGY LA English DT Article ID FLOW-CYTOMETRY; IMMUNE-SYSTEM; RECEPTORS; SPACEFLIGHT; ANTIBODIES; INSULIN; STRESS; PLASMA; CELLS AB Reduced in vitro mitogen-stimulated proliferative responses have routinely been observed from astronauts' mononuclear leucocytes following space flight. This study investigated the effect of space flight on subpopulations of peripheral blood mononuclear cells from 30 shuttle astronauts prior to launch, upon landing and 3 days after flight. The total number of peripheral blood leucocytes, granulocytes and monocytes were increased after space flight (5.7 +/- 0.2 versus 7.0 +/- 0.2; 3.1 +/- 0.1 versus 5.0 +/- 0.1; and 0.16 +/- 0.02 versus 0.25 +/- 0.28 x 10(3) cells/mm3, respectively) whereas lymphocytes were decreased (2.2+/-0.1 versus 1.7+/-0.1 x 10(3) cells/mm3). Flow cytometry analysis on Ficoll-Hypaque isolated mononuclear cells upon landing revealed significant decreases in T-inducer (CD4+, Leu-8+; 32 +/- 2 versus 23+/-2%) and T-cytotoxic lymphocytes (CD8+, CD11b-; 17 +/-1 versus 12 +/- 1%),and increases in monocytes (CD14+; 13 +/- 1 versus 21 +/- 1%) compared to pre-flight and post-flight samples whereas B cells (CD19+), T-helper (CD4+, Leu-8-) and T-suppressor (CD8+, CD11b+) populations did not change. Additional phenotypic analysis of these mononuclear leucocytes from 10 crew members upon landing revealed a reduction in natural killer (NK) cells (CD16+ or CD56+; 9 +/- 1 versus 3 +/- 1%) and an increase in monocytes that were negative for insulin and insulin-like growth factor-1 (IGF-1) receptor expression. Flow cytometric analysis indicated these hormone receptor negative monocytes were smaller and less granular than receptor positive monocytes. Therefore, a novel population of monocytes may be released into the peripheral blood during the stress of space flight or upon landing. These findings may explain some of the diverse in vitro immunological and endocrine changes observed in crew members following space flight. C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,HOUSTON,TX 77058. UNIV TEXAS,MED BRANCH,DEPT MED,GALVESTON,TX 77550. RP MEEHAN, RT (reprint author), UNIV COLORADO,HLTH SCI CTR,DEPT MED,BOX B115,4200 E 9TH AVE,DENVER,CO 80262, USA. NR 22 TC 63 Z9 68 U1 0 U2 4 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0019-2805 J9 IMMUNOLOGY JI Immunology PD JUL PY 1992 VL 76 IS 3 BP 491 EP 497 PG 7 WC Immunology SC Immunology GA JD876 UT WOS:A1992JD87600024 PM 1326479 ER PT J AU DRUYAN, LM HASTENRATH, S AF DRUYAN, LM HASTENRATH, S TI GCM SIMULATION OF THE SAHEL 1984 DROUGHT WITH ALTERNATIVE SPECIFICATIONS OF OBSERVED SST SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Note DE SAHEL DROUGHT 1984; GCM; SST ID RAINFALL AB Two climate simulations using the NASA/Goddard Institute for Space Studies coarse-resolution GCM are compared in order to investigate the sensitivity of modelled summer precipitation over West Africa to the specification of observed sea-surface temperatures (SST). Both experiments used analyses of observed SST for the boreal spring and summer of 1984, but one was derived from NOAA publications while the second came from COADS archives. Values of the NOAA SST for the tropical Atlantic were somewhat higher during June-August, leading to larger modelled evaporation rates and a model hindcast of heavy precipitation over West Africa in August, contrary to observational evidence. By comparison, dry conditions were simulated using COADS SST. The results highlight the importance of quality observations of SST and they demonstrate how sensitive the GCM is to these data. C1 COLUMBIA UNIV,NEW YORK,NY 10025. UNIV WISCONSIN,DEPT METEOROL,MADISON,WI 53706. RP DRUYAN, LM (reprint author), NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 9 TC 7 Z9 7 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD JUL-AUG PY 1992 VL 12 IS 5 BP 521 EP 526 DI 10.1002/joc.3370120508 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JG783 UT WOS:A1992JG78300007 ER PT J AU MATTHIES, L AF MATTHIES, L TI STEREO VISION FOR PLANETARY ROVERS - STOCHASTIC MODELING TO NEAR REAL-TIME IMPLEMENTATION SO INTERNATIONAL JOURNAL OF COMPUTER VISION LA English DT Article ID COMPUTATION; NAVIGATION; SCALE AB NASA scenarios for lunar and planetary missions include robotic vehicles that function in both teleoperated and semi-autonomous modes. Under teleoperation, on-board stereo cameras may provide 3-D scene information to human operators via stereographic displays; likewise, under semi-autonomy, machine stereo vision may provide 3-D information for obstacle avoidance. In the past, the slow speed of machine stereo vision systems has posed a hurdle to the semi-autonomous scenario; however, recent work at JPL and other laboratories has produced stereo systems with high reliability and near real-time performance for low-resolution image pairs. In particular, JPL has taken a significant step by achieving the first autonomous, cross-country robotic traverses (of up to 100 meters) to use stereo vision, with all computing on-board the vehicle. Here, we describe the stereo vision system, including the underlying statistical model and the details of the implementation. The statistical and algorithmic aspects employ random field models of the disparity map, Bayesian formulations of single-scale matching, and area-based image comparisons. The implementation builds bandpass image pyramids and produces disparity maps from the 60 x 64 level of the pyramids at rates of up to two seconds per image pair. All vision processing is done in one 68020 augmented with Datacube image processing boards. We argue that the overall approach provides a unifying paradigm for practical, domain-independent stereo ranging. We close with a discussion of practical and theoretical issues involved in evaluating and extending the performance of the stereo system. RP MATTHIES, L (reprint author), JET PROP LAB,ROBOT SYST & ADV COMP TECHNOL SECT,PASADENA,CA 91109, USA. NR 54 TC 100 Z9 103 U1 0 U2 8 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0920-5691 J9 INT J COMPUT VISION JI Int. J. Comput. Vis. PD JUL PY 1992 VL 8 IS 1 BP 71 EP 91 DI 10.1007/BF00126401 PG 21 WC Computer Science, Artificial Intelligence SC Computer Science GA JF613 UT WOS:A1992JF61300004 ER PT J AU SULLIVAN, RM SALAMON, NJ AF SULLIVAN, RM SALAMON, NJ TI A FINITE-ELEMENT METHOD FOR THE THERMOCHEMICAL DECOMPOSITION OF POLYMERIC MATERIALS .2. CARBON PHENOLIC COMPOSITES SO INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE LA English DT Article ID MATHEMATICAL-MODEL; WOOD PYROLYSIS AB A previously developed formulation for modeling the thermomechanical behavior of chemically decomposing, polymeric materials is verified by simulating the response of carbon phenolic specimens during two high temperature tests: restrained thermal growth and free thermal expansion. Plane strain and plane stress models are used to simulate the specimen response, respectively. In addition, the influence of the poroelasticity constants upon the specimen response is examined through a series of parametric studies. C1 PENN STATE UNIV,DEPT ENGN SCI & MECH,UNIV PK,PA 16802. RP SULLIVAN, RM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ED24,HUNTSVILLE,AL 35812, USA. NR 10 TC 26 Z9 28 U1 2 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0020-7225 J9 INT J ENG SCI JI Int. J. Eng. Sci. PD JUL PY 1992 VL 30 IS 7 BP 939 EP 951 DI 10.1016/0020-7225(92)90021-8 PG 13 WC Engineering, Multidisciplinary SC Engineering GA HU434 UT WOS:A1992HU43400010 ER PT J AU GURUSWAMY, GP AF GURUSWAMY, GP TI NAVIER-STOKES COMPUTATIONS ON SWEPT-TAPERED WINGS, INCLUDING FLEXIBILITY SO JOURNAL OF AIRCRAFT LA English DT Article AB A procedure to couple the Navier-Stokes solutions with modal structural equations of motion is presented for computing aeroelastic responses of flexible fighter wings. The Navier-Stokes flow equations are solved by a finite difference scheme with dynamic grids. The coupled aeroelastic equations of motion are solved using the linear-acceleration method. The configuration-adaptive dynamic grids are time-accurately generated using the aeroelastically deformed shape of the wing. The coupled calculations are compared with experiments when available. Effects of flexibility and pitch rate are demonstrated for flows with vortices. RP GURUSWAMY, GP (reprint author), NASA,AMES RES CTR,APPL COMPUTAT FLUIDS BRANCH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 5 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1992 VL 29 IS 4 BP 588 EP 597 DI 10.2514/3.46206 PG 10 WC Engineering, Aerospace SC Engineering GA JG857 UT WOS:A1992JG85700011 ER PT J AU HAERING, EA AF HAERING, EA TI AIRDATA CALIBRATION TECHNIQUES FOR MEASURING ATMOSPHERIC WIND PROFILES SO JOURNAL OF AIRCRAFT LA English DT Article AB The research airdata system of an instrumented F-104 aircraft has been calibrated to measure winds aloft in support of the space shuttle wind measurement investigation at the National Aeronautics and Space Administration Dryden Flight Research Facility. For this investigation, wind measurement accuracies comparable to those obtained from Jimsphere balloons were desired. This required an airdata calibration more accurate than needed for most aircraft research programs. The F-104 aircraft was equipped with a research pitot-static noseboom with integral angle-of-attack and flank angle-of-attack vanes and a ring-laser-gyro inertial reference unit. Tower fly-bys and radar acceleration-decelerations were used to calibrate Mach number and total temperature. Angle of attack and angle of sideslip were calibrated with a trajectory a multiple-state linear Kalman filter. The F-104 aircraft and instrumentation configuration, flight test data corrections, calibration techniques, and resulting calibrations and data repeatability are presented. Recommendations for future airdata systems on aircraft used to measure winds aloft are also given. RP HAERING, EA (reprint author), NASA,DRYDEN FLIGHT RES FACIL,AERODYNAM BRANCH,EDWARDS,CA 93523, USA. NR 0 TC 3 Z9 3 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1992 VL 29 IS 4 BP 632 EP 639 DI 10.2514/3.46212 PG 8 WC Engineering, Aerospace SC Engineering GA JG857 UT WOS:A1992JG85700017 ER PT J AU WOODWARD, RP AF WOODWARD, RP TI NOISE OF 2 HIGH-SPEED MODEL COUNTER-ROTATION PROPELLERS AT TAKEOFF APPROACH CONDITIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB Modern high-performance turboprop aircraft offer the promise of considerable fuel savings while still allowing for a cruise speed similar to that of current turbofan aircraft. However, there is considerable concern about the potential noise generated by such aircraft, which includes both in-flight cabin noise and community noise during takeoff and landing. This paper presents acoustic results for two model counter-rotation propellers which were tested in the NASA Lewis 9- x 15-ft Anechoic Wind Tunnel. The propellers had a common forward rotor, but the diameter of the aft rotor of the second propeller was reduced in an effort to reduce its interaction with the forward rotor tip vortex. The propellers were tested at Mach 0.20, which is representative of takeoff/approach operation. Acoustic results are presented for these propellers which show the effect of rotor spacing, reduced aft rotor diameter, operation at angle-of-attack, blade loading, and blade number. Limited aerodynamic results are also presented to establish the propeller operating conditions. RP WOODWARD, RP (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1992 VL 29 IS 4 BP 679 EP 685 DI 10.2514/3.46219 PG 7 WC Engineering, Aerospace SC Engineering GA JG857 UT WOS:A1992JG85700024 ER PT J AU LEVIN, D KATZ, J AF LEVIN, D KATZ, J TI SELF-INDUCED ROLL OSCILLATIONS OF LOW-ASPECT-RATIO RECTANGULAR WINGS SO JOURNAL OF AIRCRAFT LA English DT Article AB Experimental investigation of small-aspect-ratio rectangular wings mounted on a free-to-roll sting balance indicated that self-induced roll oscillations are possible when the aspect ratio of such wings is less than 0.5. The oscillations are probably driven by the periodic changes in the location and strength of the side-edge votices, as it has been shown for the "wing rock" of delta wings, where similar changes in the leading-edge vortex strength and position cause the roll oscillations. During the roll-oscillation cycle, the roll angle, normal force, and the side force were recorded and presented for three wings with aspect ratios of 0.25, 0.35, and 0.47. These data indicate that the lift loss during roll oscillations of rectangular wings is less than what was measured for similar delta wings. Also, the flowfield of such slender rectangular wings at high angles of attack is more complicated than the flowfield over slender delta wings, due to the additional leading-edge vortex. RP LEVIN, D (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 9 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1992 VL 29 IS 4 BP 698 EP 702 DI 10.2514/3.46222 PG 5 WC Engineering, Aerospace SC Engineering GA JG857 UT WOS:A1992JG85700027 ER PT J AU PERRY, B POTOTZKY, AS WOODSVEDELER, JA AF PERRY, B POTOTZKY, AS WOODSVEDELER, JA TI NASA INVESTIGATION OF A CLAIMED OVERLAP BETWEEN 2 GUST RESPONSE ANALYSIS-METHODS - REPLY SO JOURNAL OF AIRCRAFT LA English DT Note RP PERRY, B (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1992 VL 29 IS 4 BP 743 EP 744 DI 10.2514/3.56860 PG 2 WC Engineering, Aerospace SC Engineering GA JG857 UT WOS:A1992JG85700045 ER PT J AU STOUT, J RODGERS, EB AF STOUT, J RODGERS, EB TI NIMBUS-7 TOTAL OZONE OBSERVATIONS OF WESTERN NORTH PACIFIC TROPICAL CYCLONES SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SEASON TYPHOON DEVELOPMENT; UPPER TROPOSPHERIC TROUGH; ANGULAR-MOMENTUM; OUTFLOW LAYER; INTENSITY; FLUXES AB The Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) was used to map the distribution of total ozone around western North Pacific tropical cyclones from 1979 to 1982. The strong correlation between total ozone distribution and tropopause height found in the subtropical and midlatitudes made it possible for TOMS to monitor the propagation of upper-tropospheric waves and the mutual adjustment between these waves and tropical cyclones during their interaction. Changes in these total ozone patterns reflect the three-dimensional upper-tropospheric transport processes that are involved in tropical cyclone intensity and intensity and motion changes. The total ozone distributions indicate that 1) the mean upper-tropospheric circulations associated with western North Pacific and Atlantic tropical cyclones are similar; 2) more intense tropical cyclones have higher tropopauses around their centers; 3) more intense tropical cyclones have higher tropopauses on the anticyclonic-shear side of their outflow jets, which indicate that the more intense tropical cyclones have stronger outflow channels than less intense systems; 4) tropical cyclones that intensify (do not intensify) are within 10-degrees (15-degrees) latitude of weak (strong) upper-tropospheric troughs that are moderately rich (very rich) in total ozone; and 5) tropical cyclones turn to the left (right) when they move within approximately 15-degrees latitude downstream of an ozone-poor (ozone-rich) upper-tropospheric ridge (trough). C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 912,GREENBELT,MD 20771. GEN SCI CORP,LAUREL,MD. NR 42 TC 17 Z9 19 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD JUL PY 1992 VL 31 IS 7 BP 758 EP 783 DI 10.1175/1520-0450(1992)031<0758:TOOOWN>2.0.CO;2 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JB334 UT WOS:A1992JB33400011 ER PT J AU SUTTLES, JT WIELICKI, BA VEMURY, S AF SUTTLES, JT WIELICKI, BA VEMURY, S TI TOP-OF-ATMOSPHERE RADIATIVE FLUXES - VALIDATION OF ERBE SCANNER INVERSION ALGORITHM USING NIMBUS-7 ERB DATA SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID BUDGET; EARTH AB To derive top-of-atmosphere radiative fluxes from measurements of the Earth Radiation Budget Experiment (ERBE) scanning radiometers, it is necessary to convert radiance observations to fluxes. Two key steps of the ERBE radiance-to-flux conversion are the identification of the scene being viewed and the application of an angular model for the particular scene. In this study, the ERBE algorithm is applied to the Nimbus-7 earth radiation budget (ERB) scanner data for June 1979 to analyze the performance of this inversion method in deriving top-of-atmosphere albedos and longwave radiative fluxes. The performance is assessed by comparing ERBE algorithm results with appropriate results derived using the sorting-by-angular-bins (SAB) method, the ERB MATRIX algorithm, and the "new-cloud ERB" (NCLE) algorithm. Comparisons are made for top-of-atmosphere albedos, longwave fluxes, viewing zenith-angle dependence of derived albedos and longwave fluxes, and cloud fractional coverage. Using the SAB method as a reference, the rms accuracy of monthly average ERBE-derived results are estimated to be 0.0165 (5.6 W m-2) for albedos (shortwave fluxes) and 3.0 W m-2 for longwave fluxes. The ERBE-derived results were found to depend systematically on the viewing zenith angle, varying from near nadir to near the limb by about 10% for albedos and by 6%-7% for longwave fluxes. Analyses indicated that the ERBE angular models are the most likely source of the systematic angular dependences. Comparison of the ERBE-derived cloud fractions. based on a maximum-likelihood estimation method, with results from the NCLE showed agreement within about 10%. Little correlation was found between regional albedo and longwave-nux differences and corresponding cloud-fraction differences. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. SCI MANAGEMENT & APPL RES TECHNOL INC,SILVER SPRING,MD. NR 14 TC 47 Z9 47 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD JUL PY 1992 VL 31 IS 7 BP 784 EP 796 DI 10.1175/1520-0450(1992)031<0784:TOARFV>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JB334 UT WOS:A1992JB33400012 ER PT J AU WU, RLC RAI, AK GARSCADDEN, A KEE, P DESAI, HD MIYOSHI, K AF WU, RLC RAI, AK GARSCADDEN, A KEE, P DESAI, HD MIYOSHI, K TI SYNTHESIS AND CHARACTERIZATION OF FINE-GRAIN DIAMOND FILMS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID CHEMICAL-VAPOR-DEPOSITION; GROWTH AB A fine grain diamond film has been developed by microwave plasma assisted chemical vapor deposition. Various analytical techniques, including Rutherford backscattering, proton recoil analysis, Raman spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. The grain size of the film was determined from bright and dark field electron micrographs, and found to be 200-1000 angstrom. The films exhibited good optical transmission between 2.5 and 10-mu-m, with a calculated absorption coefficient of 490 cm-1. The friction coefficients of this film were found to be 0.035 and 0.030 at dry nitrogen and humid air environments, respectively, and the films had low wear rates. C1 WRIGHT LAB, WRIGHT PATTERSON AFB, OH 45433 USA. CVD INC, WOBURN, MA 01801 USA. NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP WU, RLC (reprint author), UES INC, 4401 DAYTON XENIA RD, DAYTON, OH 45432 USA. NR 16 TC 42 Z9 43 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 1 PY 1992 VL 72 IS 1 BP 110 EP 116 DI 10.1063/1.352167 PG 7 WC Physics, Applied SC Physics GA JB347 UT WOS:A1992JB34700019 ER PT J AU WATHEN, AJ AF WATHEN, AJ TI OPTIMAL MOVING GRIDS FOR TIME-DEPENDENT PARTIAL-DIFFERENTIAL EQUATIONS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID FINITE-ELEMENTS; ERROR C1 UNIV BRISTOL,SCH MATH,BRISTOL BS8 1TW,AVON,ENGLAND. RP WATHEN, AJ (reprint author), NASA,AMES RES CTR,RIACS,MOFFETT FIELD,CA 94035, USA. NR 18 TC 5 Z9 5 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUL PY 1992 VL 101 IS 1 BP 51 EP 54 DI 10.1016/0021-9991(92)90041-V PG 4 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JF127 UT WOS:A1992JF12700004 ER PT J AU POINSOT, TJ LELE, SK AF POINSOT, TJ LELE, SK TI BOUNDARY-CONDITIONS FOR DIRECT SIMULATIONS OF COMPRESSIBLE VISCOUS FLOWS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID NAVIER-STOKES CALCULATIONS; LINEAR HYPERBOLIC SYSTEMS; NUMERICAL-SIMULATION; FLUID-DYNAMICS; EQUATIONS; WAVES C1 STANFORD UNIV,CTR TB RES,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 43 TC 1383 Z9 1424 U1 14 U2 93 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUL PY 1992 VL 101 IS 1 BP 104 EP 129 DI 10.1016/0021-9991(92)90046-2 PG 26 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JF127 UT WOS:A1992JF12700009 ER PT J AU YANG, KS SPALART, PR FERZIGER, JH AF YANG, KS SPALART, PR FERZIGER, JH TI NUMERICAL-STUDIES OF NATURAL TRANSITION IN A DECELERATING BOUNDARY-LAYER SO JOURNAL OF FLUID MECHANICS LA English DT Article ID NAVIER-STOKES EQUATIONS; SECONDARY INSTABILITY; SHEAR FLOWS; STABILITY AB Laminar-turbulent transition in the decelerating boundary layer of Gad-el-Hak et al. (1984) is studied by solving the incompressible, time-dependent, three-dimensional Navier-Stokes equations numerically. The temporal and spatial evolution of the experimental flow structures is approximated with spatial periodicity and temporal evolution while maintaining mean-velocity profiles appropriate to the spatially-developing flow. Other than the mean flow, the initial flow fields include only small-amplitude white random noise. This and the large streamwise and spanwise dimensions of the numerical domain allow unstable waves to be selected by the dynamics, instead of being imposed arbitrarily as in previous numerical studies. In that sense, the transition is natural. In the early stages of transition. two-dimensional and slightly oblique waves grow rapidly owing to inflexional instability. Their subsequent nonlinear interactions trigger the breakdown and create a pattern of LAMBDA-vortices. The patterns of LAMBDA-vortices are more irregular than those found in ribbon-induced transition. The tips of the LAMBDA-vortices are rarely aligned with the flow direction, and they appear in local patches. consistent with the experimental visualizations of Gad-el-Hak et al. A simple model based on the interference of multiple modes of instability accounts for these features, but the specific pattern of LAMBDA-vortices depends on the random content of the initial flow field. A simulation of the later stages of transition is performed with higher numerical resolution. showing that the 'naturally-born' LAMBDA-vortices undergo breakdown processes similar to those of their ribbon-induced counterparts. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP YANG, KS (reprint author), STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305, USA. NR 41 TC 7 Z9 7 U1 0 U2 3 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUL PY 1992 VL 240 BP 433 EP 468 DI 10.1017/S0022112092000156 PG 36 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JH345 UT WOS:A1992JH34500015 ER PT J AU SINGER, BA ZANG, TA AF SINGER, BA ZANG, TA TI TOLLMIEN-SCHLICHTING WAVE DEAN VORTEX INTERACTIONS IN CURVED CHANNEL FLOW SO JOURNAL OF FLUID MECHANICS LA English DT Article ID NON-LINEAR STABILITY; NONLINEAR-INTERACTION; GORTLER VORTICES AB Evidence from direct numerical simulations and from a recent weakly nonlinear theory is presented which shows that the weakly nonlinear results of Daudpota, Hall & Zang (1988) make incorrect predictions for the influence of the Tollmien-Schlichting wave on the Dean vortex. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP SINGER, BA (reprint author), HIGH TECHNOL CORP,HAMPTON,VA 23666, USA. NR 10 TC 1 Z9 1 U1 0 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUL PY 1992 VL 240 BP 681 EP 684 DI 10.1017/S0022112092000260 PG 4 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JH345 UT WOS:A1992JH34500026 ER PT J AU HUNG, RJ LEE, CC LESLIE, FW AF HUNG, RJ LEE, CC LESLIE, FW TI SIMILARITY RULES IN GRAVITY JITTER-RELATED SPACECRAFT LIQUID PROPELLANT SLOSH WAVES EXCITATION SO JOURNAL OF FLUIDS AND STRUCTURES LA English DT Article ID ROTATING HELIUM DEWAR; BUBBLE; ENVIRONMENT; STABILITY C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP HUNG, RJ (reprint author), UNIV ALABAMA,HUNTSVILLE,AL 35899, USA. NR 47 TC 30 Z9 30 U1 1 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0889-9746 J9 J FLUID STRUCT JI J. Fluids Struct. PD JUL PY 1992 VL 6 IS 4 BP 493 EP 522 DI 10.1016/0889-9746(92)90028-2 PG 30 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA JE263 UT WOS:A1992JE26300006 ER PT J AU AJELLO, JM JAMES, GK KANIK, I FRANKLIN, BO AF AJELLO, JM JAMES, GK KANIK, I FRANKLIN, BO TI THE COMPLETE UV SPECTRUM OF SO2 BY ELECTRON-IMPACT .1. THE VACUUM ULTRAVIOLET-SPECTRUM SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EXTREME ULTRAVIOLET; CROSS-SECTIONS; PLASMA TORUS; IO; JUPITER; SULFUR; EXCITATION; ENCOUNTER; EMISSION; OXYGEN AB We have measured the vacuum ultraviolet (VUV) emission cross sections of SO2 from 40 to 200 nm in the laboratory in a crossed beam experiment. The wavelength range comprised the extreme ultraviolet (EUV) spectrum, from 40 to 120 nm, and the far ultraviolet (FUV) spectrum, from 120 to 200 nm. The EUV and FUV emission spectra induced by electron impact consist of atomic multiplets of S I, II, and III and O I, II, and III. The studies included the measurement of excitation functions of the strongest multiplets from 0 to 1 keV impact energy and the identification of dissociation processes from the analysis of the threshold excitation function. The O I (98.9 nm) resonance multiplet (g3P-3D) is the strongest EUV feature from electron impact induced fluorescence of SO2 with a peak cross section of 7.82 +/- 1.59 x 10(-19) cm2 at 125 eV electron impact energy. The O I (130.4 nm) multiplet (g3P-3S) resonance transition is the strongest feature in the FUV, with a peak cross section of 1.98 +/- 0.44 x 10(-18) cm2 at 90 eV. The strongest feature of S I in the VUV is the S I (147.9 nm) multiplet (g3P-3D) resonance transition, with a peak cross section of 1.52 +/- 0.33 x 10(-18) cm2 at 90 eV. Dissociation-excitation cross sections of SO2 are important contributors to the total inelastic cross section of SO2 gas interacting with electrons. These cross sections are used in neutral cloud theory models of the Io atmosphere. The laboratory spectrum at low energy (approximately 22 eV) matches a recently obtained IUE FUV spectrum of Io. The comparison represents evidence of a thin or intermediate atmosphere of SO2 that is directly impacted by the plasma torus. The existence of an atmosphere on Io embedded in the corotating torus plasma is an important remote sensing target for the Hubble Space Telescope, Goddard High Resolution Spectrograph and Faint Object Spectrograph, and Galileo EUV and FUV spectrometers, among other present and planned VUV studies of the Jovian system. RP AJELLO, JM (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 40 TC 30 Z9 30 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1992 VL 97 IS A7 BP 10473 EP 10500 DI 10.1029/92JA00296 PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JC484 UT WOS:A1992JC48400001 ER PT J AU AJELLO, JM JAMES, GK KANIK, I AF AJELLO, JM JAMES, GK KANIK, I TI THE COMPLETE UV SPECTRUM OF SO2 BY ELECTRON-IMPACT .2. THE MIDDLE ULTRAVIOLET-SPECTRUM SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ROTATIONAL STRUCTURE; CROSS-SECTIONS; SULFUR-DIOXIDE; ABSORPTION; ORBITER; VENUS; IO AB We have measured the middle ultraviolet (MUV) electron impact induced fluorescence spectrum of SO2 from 200 to 430 nm in a crossed beam experiment. The spectrum is dominated by two features at the experimental resolution of 0.5 nm. These two features are referred to as MUV1 and MUV2. MUV1 is the SO(A3-PI --> X3-SIGMA-) band system extending from 240 to 265 nm produced by dissociative excitation. MUV2 is a blend of the SO2 (A approximately(1A2), B approximately(1B1) --> X approximately(1A1)) and SO2+(C approximately(2B2) --> X approximately(2A1)) molecular band systems in the range 264-430 nm. In addition, the excitation function measurements of MUV2 indicate that low-energy electrons effectively prepare SO2 in one or more electronically excited triplet states that involve the SO2 (a approximately(3B1)) state by direct excitation and/or cascading. A candidate triplet band system for this emission process is the E approximately-a approximately electronic transition. This emission process is the largest contributor to the MUV2 emission cross section at low electron impact energy. The peak cross section for MUV1 occurs at 20 eV with a value of 25.0 +/- 5.5 x 10(-19) cm2. The peak cross section for MUV2 arises at 9 eV with a value of 368 +/- 81 x 10(-19) cm2. The laboratory measurements of the excitation functions of both MUV features were made from 0 to 1 keV. The emission cross sections are an important part of the total inelastic cross section of SO2 needed in modeling the Io atmosphere. The laboratory results give a plausible explanation of the Io auroral hot spots observed by Voyager 2. RP AJELLO, JM (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 27 TC 32 Z9 32 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1992 VL 97 IS A7 BP 10501 EP 10512 DI 10.1029/92JA00295 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JC484 UT WOS:A1992JC48400002 ER PT J AU HOEGY, WR MAHAJAN, KK AF HOEGY, WR MAHAJAN, KK TI SOLAR EUV INDEX FOR AERONOMICAL STUDIES AT EARTH FROM LANGMUIR PROBE PHOTOELECTRON MEASUREMENTS ON THE PIONEER VENUS ORBITER SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IONIZATION FREQUENCIES; FLUX; MODEL; IRRADIANCE; CYCLE-21 AB We present a solar EUV index for aeronomical studies at Earth, obtained from the Langmuir probe measurement of photoelectron current on the Pioneer Venus orbiter (PVO). When the probe is in the solar wind and is negatively biased, the current, I(pe), is mainly due to the impact of solar EUV photons with energies above the work function of the probe. I(pe) thus measures the total EUV flux over the wavelength interval from about 30 nm to Lyman alpha; on Venus this solar flux, V(EUV), was defined by Brace et al. (1988). When translated to the solar longitude of Earth, for Earth use, it is called E(EUV). To examine the potential of E(EUV) as a solar EUV flux index, we study the behavior of ionospheric parameters f(o)E,f(o)F1, and f(o)F2 at mid-latitude stations and compare their relationship with E(EUV) and with the 10.7-cm solar radio flux. We find f(o)F1 and f(o)F2 to be better correlated with E(EUV) than with the 10.7-cm flux. However, f(o)E is better correlated with the 10.7-cm flux, because the 10.7-cm flux is also a proxy for soft X rays, which are an important ionizing source in the E region. We also provide a table of the EUV index, E(EUV), for the period February 12, 1979, through most of 1991 which extends in time the table (of Venus values) published earlier by Brace et al. (1988). The EUV index will continue to grow until the end of the PVO mission in late 1992. C1 NATL PHYS LAB, NEW DELHI 110012, INDIA. RP HOEGY, WR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. NR 17 TC 10 Z9 10 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-SPACE JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1992 VL 97 IS A7 BP 10525 EP 10537 DI 10.1029/92JA00384 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JC484 UT WOS:A1992JC48400004 ER PT J AU EASTES, RW KILLEEN, TL WU, Q WINNINGHAM, JD HOEGY, WR WHARTON, LE CARIGNAN, GR AF EASTES, RW KILLEEN, TL WU, Q WINNINGHAM, JD HOEGY, WR WHARTON, LE CARIGNAN, GR TI AN EXPERIMENTAL INVESTIGATION OF THERMOSPHERIC STRUCTURE NEAR AN AURORAL ARC SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GENERAL-CIRCULATION MODEL; HIGH-LATITUDE THERMOSPHERE; NESTED-GRID MODEL; NEUTRAL CIRCULATION; DYNAMICS EXPLORER; ELECTRIC-FIELDS; POLAR THERMOSPHERE; HIGH-RESOLUTION; VERTICAL WINDS; GRAVITY-WAVES AB Observations of thermospheric parameters, made from the Dynamics Explorer 2 (DE 2) spacecraft during three successive orbital crossings of quiescent dusk sector auroral arc, have been compared with the predictions of three fine-grid auroral arc models. DE 2 measured the ion and neutral winds, electron and neutral temperatures, neutral composition, and energetic auroral electron spectra (5 eV to 32 keV) at approximately 320 km altitude. These observations were at high spatial and temporal resolution, suitable for comparisons with the models. The observed zonal and meridional neutral winds near the arc were greater than the model predictions, probably because of the presence of stronger electric fields and higher ion and neutral densities during the observations than were used in the models. The measured vertical winds were also larger than the corresponding model values. The DE 2 composition measurements showed a local increase of the N2/O ratio in the arc, which is interpreted to be a result of the upward motion of N2-rich air. A reduction in the measured neutral temperature of approximately 100 K in the arc, relative to temperatures on either side, was found for all three arc crossings. Of the three theoretical models examined, only one shows any tendency for the neutral thermospheric temperature to drop in the auroral arc, and the decrease calculated is significantly less than the observed temperature change. A simple calculation of the adiabatic cooling effect of the observed upward motion yields a temperature drop of approximately 160 K, comparable with the observed temperature reduction (approximately 100 K). C1 UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. SW RES INST,SAN ANTONIO,TX 78228. RP EASTES, RW (reprint author), PHILLIPS LAB GPIM,BEDFORD,MA 01730, USA. NR 56 TC 14 Z9 14 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1992 VL 97 IS A7 BP 10539 EP 10549 DI 10.1029/92JA00168 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JC484 UT WOS:A1992JC48400005 ER PT J AU SAKA, O IIJIMA, T YAMAGISHI, H SATO, N BAKER, DN AF SAKA, O IIJIMA, T YAMAGISHI, H SATO, N BAKER, DN TI EXCITATION OF PC-5 PULSATIONS IN THE MORNING SECTOR BY A LOCAL INJECTION OF PARTICLES IN THE MAGNETOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SCALE BIRKELAND CURRENTS; LATITUDE BOUNDARY-LAYER; FIELD-ALIGNED CURRENTS; MAGNETIC PULSATIONS; GEOMAGNETIC-FIELD; LINE RESONANCES; MICROPULSATIONS AB We have determined a characteristic of Pc 5 pulsation in the morning sector by use of ground magnetometer and riometer (cosmic noise absorption) data, in conjunction with data acquired with satellites which include the magnetic fields above the ionosphere and electron fluxes at geosynchronous orbit. We have found that the onset of a flux increase in energetic electrons of 30 keV to 200 keV at geosynchronous orbit almost coincides with the onset of Pc 5 pulsation activity and riometer absorption on the ground. We have ascertained that when the Pc 5 pulsation occurs on the ground, the large-scale Birkeland current system observed at ionospheric altitude splits into a number of small-scale Birkeland current pairs. We could infer that the electron flux enhancement, presumably supplied from the tail plasma sheet associated with the substorm onset, provides stress to cause the background large-scale plasma vortex to split into the small-scale vortices. We suggest that the field-aligned currents in the small-scale vortices propagate along the field lines and sustain the standing Alfvenic oscillations at several different, but neighboring shells of the field lines. C1 UNIV TOKYO,GEOPHYS RES LAB,TOKYO 113,JAPAN. NATL INST POLAR RES,TOKYO 173,JAPAN. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP SAKA, O (reprint author), KYUSHU UNIV 33,DEPT PHYS,FUKUOKA 812,JAPAN. NR 31 TC 16 Z9 16 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1992 VL 97 IS A7 BP 10693 EP 10701 DI 10.1029/92JA00441 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JC484 UT WOS:A1992JC48400015 ER PT J AU GREENSTADT, EW CORONITI, FV MOSES, SL SMITH, EJ AF GREENSTADT, EW CORONITI, FV MOSES, SL SMITH, EJ TI PLASMA-WAVE PROFILES OF EARTHS BOW SHOCK AT LOW MACH NUMBERS - ISEE-3 OBSERVATIONS ON THE FAR FLANK SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; UPSTREAM; PROTONS AB The Earth's bow shock is weak along its distant flanks where the projected component of solar wind velocity normal to the hyperboloidal surface is only a fraction of the total free stream velocity, severely reducing the local Mach number. We present a survey of selected crossings far downstream from the subsolar shock, delineating the overall plasma wave (pw) behavior of a selected set of nearly perpendicular crossings and another set of limited Mach number but broad geometry; we include their immediate upstream regions. The result is a generalizable pw signature, or signatures, of low Mach number shocks and some likely implications of those signatures for the weak shock's plasma physical processes on the flank. We find the data consistent with the presence of ion beam interactions producing noise ahead of the shock in the ion acoustic frequency range. One subcritical case was found whose pw noise was presumably related to a reflected ion population just as in stronger events. The presence or absence, and the amplitudes, of pw activity are explainable by the presence or absence of a population of upstream ions controlled by the component of interplanetary magnetic field normal to the solar wind flow. C1 JET PROP LAB,PASADENA,CA 91109. RP GREENSTADT, EW (reprint author), TRW CO INC,DEPT ELECTROMAGNET TECHNOL,RI-2020,1 SPACE PK,REDONDO BEACH,CA 90278, USA. NR 17 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1992 VL 97 IS A7 BP 10841 EP 10848 DI 10.1029/91JA03049 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JC484 UT WOS:A1992JC48400026 ER PT J AU FAIRFIELD, DH AF FAIRFIELD, DH TI ADVANCES IN MAGNETOSPHERIC STORM AND SUBSTORM RESEARCH - 1989-1991 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Review ID NEAR-EARTH MAGNETOTAIL; TRAVELING COMPRESSION REGIONS; PLASMA SHEET; GROWTH-PHASE; PARTICLE-ACCELERATION; GEOMAGNETIC-ACTIVITY; GEOSTATIONARY ORBIT; IMP-8 OBSERVATIONS; BOUNDARY-LAYER; NEUTRAL SHEET AB Geomagnetic storms represent the magnetospheric response to fast solar wind and unusually large southward interplanetary magnetic fields that are caused by solar processes and resulting dynamics in the interplanetary medium. The solar wind/magnetosphere interaction is, however, more commonly studied via smaller, more common, magnetospheric substorms. Accumulating evidence suggests that two separate magnetospheric current systems are important during magnetospheric substorms. Currents directly driven by the solar wind/magnetosphere interaction produce magnetic field variations that make important contributions to the AE index but have little relation to the many effects traditionally associated with sudden substorm onsets. Currents driven by energy unloaded from the magnetotail form the nightside current wedge and are associated with onset effects such as auroral breakup, field dipolarization, and particle acceleration. Observations are gradually leading to a coherent picture of the interrelations among these various onset phenomena, but their cause remains a controversial question. The abrupt nature of substorm onsets suggests a magnetospheric instability, but doubt remains as to its nature and place of origin. Measurements increasingly suggest the region of 7-10 R(E) near midnight as the likely point of origin, but it is not clear that the long-popular tearing mode can go unstable this close to the Earth, where it may be stabilized by a small northward field component. Also the tailward flows that would be expected tailward of a near-Earth neutral line are seldom seen inside of 19 R(E). The changing magnetic field configuration during substorms means that existing static models cannot be used to map phenomena between the magnetosphere and the ground at these interesting times. Although first steps are being made toward creating time dependent models, the lack of such models remains an important limitation to further progress. RP FAIRFIELD, DH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 70 TC 49 Z9 49 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1992 VL 97 IS A7 BP 10865 EP 10874 DI 10.1029/92JA00326 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JC484 UT WOS:A1992JC48400029 ER PT J AU DUNLOP, MW FREEMAN, MP FARRUGIA, CJ AF DUNLOP, MW FREEMAN, MP FARRUGIA, CJ TI SOLAR-WIND CONTROL OF THE MAGNETOPAUSE SHAPE, LOCATION, AND MOTION - COMMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Editorial Material C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. BRITISH ANTARTIC SURVEY,CAMBRIDGE CB3 DET,ENGLAND. RP DUNLOP, MW (reprint author), UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,PRINCE CONSORT RD,LONDON SW7 2BZ,ENGLAND. RI dunlop, malcolm/F-1347-2010 NR 3 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1992 VL 97 IS A7 BP 10875 EP 10877 DI 10.1029/92JA00140 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JC484 UT WOS:A1992JC48400030 ER PT J AU SPARKS, DW JUANG, JN AF SPARKS, DW JUANG, JN TI SURVEY OF EXPERIMENTS AND EXPERIMENTAL FACILITIES FOR CONTROL OF FLEXIBLE STRUCTURES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper presents a survey of ground experiments primarily conducted in the United States and U.S. facilities dedicated to the study of active control of flexible structures. The facilities are briefly described in terms of capability, configuration, size, and instruments. Topics on the experiments include vibration suppression, slewing control, and system identification. The experiments are listed in tables containing the experiment's name, the responsible organization, a brief description of the test article configuration, and the actuator/sensor devices used in the experiment. Selected experiments will be further discussed to help illustrate the control problems. Some of the test facilities dedicated to ground testing of large space structures are discussed in more detail, to give the reader a better appreciation of ground-testing work. Several research issues are mentioned, including real-time computer systems, test article suspension, and new actuator/sensor technology development. RP SPARKS, DW (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 48 TC 22 Z9 24 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1992 VL 15 IS 4 BP 801 EP 816 DI 10.2514/3.20912 PG 16 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JE878 UT WOS:A1992JE87800001 ER PT J AU HUNG, RJ LEE, CC LESLIE, FW AF HUNG, RJ LEE, CC LESLIE, FW TI SPACECRAFT DYNAMIC DISTRIBUTION OF FLUID STRESSES ACTIVATED BY GRAVITY-JITTER-INDUCED SLOSH WAVES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID MICROGRAVITY ENVIRONMENT; FILLED CYLINDER; SPIN-UP; REORIENTATION; BUBBLE; SYSTEM AB The dynamical behavior of fluids, in particular the effect of surface tension on partially filled rotating fluids (cryogenic liquid helium and helium vapor) in a full-scale Gravity Probe-B Spacecraft propellant Dewar tank imposed by various frequencies of gravity jitters, has been investigated. Fluid stress distribution, caused by the excitation of slosh waves and their associated large-amplitude disturbances on the liquid-vapor interface, exerted on the outer and inner walls of a rotating Dewar container also has been investigated. Results show that fluid stress distributions near the outer and inner walls of the rotating Dewar are closely related to the characteristics of slosh waves excited on the liquid-vapor interface in the rotating Dewar tank. This can provide a useful tool for managing spacecraft dynamic control leading toward the control of spacecraft imbalance caused by the uneven fluid stress distribution due to slosh wave excitations at the interface between liquid and vapor propellants. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,FLUID DYNAM BRANCH,HUNTSVILLE,AL 35812. RP HUNG, RJ (reprint author), UNIV ALABAMA,MECH ENGN,HUNTSVILLE,AL 35899, USA. NR 32 TC 29 Z9 29 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1992 VL 15 IS 4 BP 817 EP 824 DI 10.2514/3.20913 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JE878 UT WOS:A1992JE87800002 ER PT J AU PAPPA, RS SCHENK, A NIEDBAL, N KLUSOWSKI, E AF PAPPA, RS SCHENK, A NIEDBAL, N KLUSOWSKI, E TI COMPARISON OF 2 DISSIMILAR MODAL IDENTIFICATION TECHNIQUES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID EIGENSYSTEM REALIZATION-ALGORITHM AB Recent laboratory results using a refined phase resonance method and the eigensystem realization algorithm on the same test structure are reported. These methods are dissimilar modal identification techniques suitable for future large spacecraft. The theory, application approach, and results obtained for each technique are summarized and compared. Although both methods worked well in this investigation, significant differences occurred in some identified mode shapes. Comparison of independently derived modal parameters provides the means for disclosing such discrepancies in flight projects. C1 GERMAN AEROSP RES ESTAB,INST AEROELASTICITY,W-3400 GOTTINGEN,GERMANY. RP PAPPA, RS (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,MAIL STOP 230,HAMPTON,VA 23665, USA. NR 19 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1992 VL 15 IS 4 BP 840 EP 846 DI 10.2514/3.20915 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JE878 UT WOS:A1992JE87800005 ER PT J AU WU, SC CHANG, CW HOUSNER, JM AF WU, SC CHANG, CW HOUSNER, JM TI FINITE-ELEMENT APPROACH FOR TRANSIENT ANALYSIS OF MULTIBODY SYSTEMS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ARTICULATED STRUCTURES; DYNAMICS AB A three-dimensional, finite element based formulation for the transient dynamics of constrained multibody systems with trusslike configurations is presented. A convected coordinate system is used to define the rigid-body motion of individual elements in the system. Deformation of each element is defined relative to its convected coordinate system. The formulation is oriented toward joint-dominated structures. Through a series of sequential transformations, the joint degree of freedom is built into the equations of motion of the element to reduce geometric constraints. Based on the derivation, a general-purpose code has been developed. Two examples are presented to illustrate the application of the code. C1 COMTEK,GRAFTON,VA 23692. NASA,LANGLEY RES CTR,COMP MECH BRANCH,HAMPTON,VA 23665. RP WU, SC (reprint author), LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666, USA. NR 10 TC 4 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1992 VL 15 IS 4 BP 847 EP 854 DI 10.2514/3.20916 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JE878 UT WOS:A1992JE87800006 ER PT J AU POTOTZKY, AS WIESEMAN, C HOADLEY, ST MUKHOPADHYAY, V AF POTOTZKY, AS WIESEMAN, C HOADLEY, ST MUKHOPADHYAY, V TI ONLINE PERFORMANCE EVALUATION OF MULTILOOP DIGITAL-CONTROL SYSTEMS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A real-time controller, developed to implement flutter suppression and rolling maneuver load alleviation control laws digitally, was tested on an aeroelastic wind-tunnel model. A controller-performance-evaluation (CPE) methodology to evaluate various multi-input/multi-output digital control systems on line using sampled digital data was also developed and tested. Modern signal processing methods were used to generate appropriate transfer matrices of the control system from the sampled time-domain data of the whole system (controller and plant). Matrix procedures were used to calculate singular values of return-difference matrices at the plant input and output points to evaluate the performance of the control system. The CPE procedures confirmed satisfactory performance of stabilizing control laws and effectively identified potentially destabilizing ones. C1 NASA,LANGLEY RES CTR,AEROSERVOELASTIC BRANCH,MS 243,HAMPTON,VA 23665. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23665. NR 18 TC 9 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1992 VL 15 IS 4 BP 878 EP 889 DI 10.2514/3.20920 PG 12 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JE878 UT WOS:A1992JE87800010 ER PT J AU JUANG, JN MAGHAMI, PG AF JUANG, JN MAGHAMI, PG TI ROBUST EIGENSYSTEM ASSIGNMENT FOR STATE ESTIMATORS USING 2ND-ORDER MODELS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID OPTIMAL PROJECTION EQUATIONS AB A novel design of a state estimator is presented using second-order dynamic equations of mechanical systems. The eigenvalues and eigenvectors of the state estimator are assigned by solving the second-order eigenvalue problem of the structural system. Three design methods for the state estimator are given in this paper. The first design method uses collocated sensors to measure the desired signals and their derivatives. The second design method uses prefilters to shift signal phases to obtain estimates of the signal derivatives. These two methods are used to build a second-order state estimator model. The third design method is the conventional one that converts a typical second-order dynamic model to a first-order model and then builds a state estimator based on the first-order model. It is shown that all three design methods for state estimation are similar. A numerical example representing a large space structure is given for illustration of the design methods presented in this paper. RP JUANG, JN (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 14 TC 28 Z9 32 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1992 VL 15 IS 4 BP 920 EP 927 DI 10.2514/3.20925 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JE878 UT WOS:A1992JE87800015 ER PT J AU PARLOS, AG SUNKEL, JW AF PARLOS, AG SUNKEL, JW TI ADAPTIVE ATTITUDE-CONTROL AND MOMENTUM MANAGEMENT FOR LARGE-ANGLE SPACECRAFT MANEUVERS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID STATION AB The fully coupled equations of motion are systematically linearized around an equilibrium point of a gravity gradient stabilized spacecraft, controlled by momentum exchange devices. These equations are then used for attitude control system design of an early Space Station Freedom flight configuration, demonstrating the errors caused by the improper approximation of the spacecraft dynamics. A full state feedback controller, incorporating gain-scheduled adaptation of the attitude gains, is developed for use during spacecraft on-orbit assembly or operations characterized by significant mass properties variations. The feasibility of the gain adaptation is demonstrated via a Space Station Freedom assembly sequence case study. The attitude controller stability robustness and transient performance during gain adaptation appear satisfactory. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE STN CONTROL SYST DEV & INTEGRAT,HOUSTON,TX 77058. RP PARLOS, AG (reprint author), TEXAS A&M UNIV SYST,DEPT NUCL ENGN,COLLEGE STN,TX 77843, USA. NR 21 TC 11 Z9 15 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1992 VL 15 IS 4 BP 1018 EP 1028 DI 10.2514/3.20937 PG 11 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JE878 UT WOS:A1992JE87800027 ER PT J AU CHAPES, SK MORRISON, DR GUIKEMA, JA LEWIS, ML SPOONER, BS AF CHAPES, SK MORRISON, DR GUIKEMA, JA LEWIS, ML SPOONER, BS TI CYTOKINE SECRETION BY IMMUNE CELLS IN SPACE SO JOURNAL OF LEUKOCYTE BIOLOGY LA English DT Article DE SPACE IMMUNOLOGY; CYTOKINES ID ACTIVATION; INTERFERON; MICROGRAVITY; MICROTUBULES; PROTEINS; MOUSE AB Cultured, bone marrow-derived macrophages, murine spleen and lymph node cells, and human lymphocytes were tested for their ability to secrete cytokines in space. Lipopolysaccharide-activated bone marrow macrophages were found to secrete significantly more interleukin-I and tumor necrosis factor when stimulated in space than when stimulated on earth. Murine spleen cells stimulated with poly I:C in space released significantly more interferon-alpha at 1 and 14 hours after stimulation than cells stimulated on earth. Similarly, murine lymph node T cells and human peripheral blood lymphocytes, stimulated with concanavalin A in space, secreted significantly more interferon-gamma than ground controls. These data suggest that space flight has a significant enhancing effect on immune cell release of cytokines in vitro. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV ALABAMA,DEPT BIOL SCI,HUNTSVILLE,AL 35899. RP CHAPES, SK (reprint author), KANSAS STATE UNIV AGR & APPL SCI,DIV BIOL,ACKERT HALL,MANHATTAN,KS 66506, USA. NR 28 TC 65 Z9 68 U1 1 U2 3 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0741-5400 J9 J LEUKOCYTE BIOL JI J. Leukoc. Biol. PD JUL PY 1992 VL 52 IS 1 BP 104 EP 110 PG 7 WC Cell Biology; Hematology; Immunology SC Cell Biology; Hematology; Immunology GA JQ368 UT WOS:A1992JQ36800015 PM 1640164 ER PT J AU HEBSUR, MG LOCCI, IE RAJ, SV NATHAL, MV AF HEBSUR, MG LOCCI, IE RAJ, SV NATHAL, MV TI INFLUENCE OF PROCESSING ON THE MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF A NBAL3-BASE ALLOY SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID SOLID-SOLUTION ALLOYS; BEHAVIOR; CREEP AB A multiphase oxidation resistant composition (Nb-67Al-7Cr-0.5Y-0.25W) based on NbAl3 was prepared by both induction melting and rapid solidification processing (RSP), followed by grinding to 75-mu-m powder and consolidating by powder metallurgy techniques (hot pressing, hot isostatic pressing, and Ceracon pressing). Constant strain rate compression tests conducted on consolidated materials in the temperature range 300-1300 K indicated that the RSP material exhibited significantly higher strength and ductility than the induction melted alloy up to 1200 K. Bend strengths measured on induction melted material were significantly lower than the corresponding compressive strengths, suggesting the brittle, flaw-sensitive nature of this alloy. The NbAlCrYW alloy exhibits a brittle-to-ductile transition around 1000 K. The constant load creep tests conducted on the induction melted alloy in the 1200-1300 K temperature range indicated that this alloy shows a power law creep dependency with a stress exponent, n, of 3.2. It was found that the specific strength of this alloy is competitive with other aluminide intermetallics. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP HEBSUR, MG (reprint author), SVERDRUP TECHNOL INC,LERC GRP,BROOK PK,OH 44142, USA. NR 30 TC 10 Z9 10 U1 1 U2 1 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD JUL PY 1992 VL 7 IS 7 BP 1696 EP 1706 DI 10.1557/JMR.1992.1696 PG 11 WC Materials Science, Multidisciplinary SC Materials Science GA JD171 UT WOS:A1992JD17100017 ER PT J AU DAMELIO, F DAUNTON, NG AF DAMELIO, F DAUNTON, NG TI EFFECTS OF SPACEFLIGHT IN THE ADDUCTOR LONGUS MUSCLE OF RATS FLOWN IN THE SOVIET BIOSATELLITE COSMOS-2044 - A STUDY EMPLOYING NEURAL CELL-ADHESION MOLECULE (N-CAM) IMMUNOCYTOCHEMISTRY AND CONVENTIONAL MORPHOLOGICAL TECHNIQUES (LIGHT AND ELECTRON-MICROSCOPY) SO JOURNAL OF NEUROPATHOLOGY AND EXPERIMENTAL NEUROLOGY LA English DT Article DE ELECTRON MICROSCOPY; IMMUNOCYTOCHEMISTRY; NEURAL CELL ADHESION MOLECULE; NEUROMUSCULAR JUNCTION; REGENERATION; SKELETAL MUSCLE ID ORIGINAL SYNAPTIC SITES; BASEMENT-MEMBRANE ZONE; ADULT SKELETAL-MUSCLE; NEUROMUSCULAR-JUNCTION; BASAL LAMINA; ACETYLCHOLINE-RECEPTORS; REGENERATING MUSCLE; NERVE; SOLEUS; FIBER AB The effects of spaceflight upon the "slow" muscle adductor longus were examined in rats flown in the Soviet Biosatellite COSMOS 2044. The techniques employed included standard methods for light microscopy, neural cell adhesion molecule (N-CAM) immunocytochemistry and electron microscopy. Light microscopic observations revealed myofiber atrophy and segmental necrosis accompanied by cellular infiltrates composed of macrophages, leukocytes and mononuclear cells. Neural cell adhesion molecule immunoreactivity (N-CAM-IR) was seen on the myofiber surface and in regenerating myofibers. Ultrastructural alterations included Z band streaming, disorganization of myofibrillar architecture, sarcoplasmic degradation, extensive segmental necrosis with apparent preservation of the basement membrane, degenerative phenomena of the capillary endothelium and cellular invasion of necrotic areas. Regenerating myofibers were identified by the presence of increased amounts of ribosomal aggregates and chains of polyribosomes associated with myofilaments. The principal electron microscopic changes of the neuromuscular junctions showed axon terminals with a decrease or absence of synaptic vesicles replaced by microtubules and neurofilaments, degeneration of axon terminals, vacant axonal spaces and changes suggestive of axonal sprouting. The present observations suggest that alterations such as myofibrillar disruption and necrosis, muscle regeneration and denervation and synaptic remodeling at the level of the neuromuscular junction may take place during spaceflight. C1 SAN JOSE STATE UNIV FDN,SAN JOSE,CA. RP DAMELIO, F (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,MAIL STOP 261-3,MOFFETT FIELD,CA 94035, USA. NR 64 TC 23 Z9 23 U1 0 U2 0 PU AMER ASSN NEUROPATHOLOGISTS INC PI LAWRENCE PA 1041 NEW HAMPSHIRE ST, LAWRENCE, KS 66044 SN 0022-3069 J9 J NEUROPATH EXP NEUR JI J. Neuropathol. Exp. Neurol. PD JUL PY 1992 VL 51 IS 4 BP 415 EP 431 PG 17 WC Clinical Neurology; Neurosciences; Pathology SC Neurosciences & Neurology; Pathology GA JC177 UT WOS:A1992JC17700004 PM 1619441 ER PT J AU IRVIN, JA NEEF, CJ KANE, KM CASSIDY, PE TULLOS, G STCLAIR, AK AF IRVIN, JA NEEF, CJ KANE, KM CASSIDY, PE TULLOS, G STCLAIR, AK TI POLYETHERS DERIVED FROM BISPHENOLS AND HIGHLY FLUORINATED AROMATICS SO JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY LA English DT Article DE FLUOROPOLYMERS; LOW DIELECTRIC CONSTANT; THERMALLY STABLE; AROMATIC POLYETHERS ID SUBSTITUTION AB A series of fluorinated aromatic polyethers was synthesized via aromatic nucleophilic substitution of highly fluorinated aromatics (1,2,4,5-tetrafluorobenzene, hexafluorobenzene, and decafluorobiphenyl) with bisphenol AF or bisphenol A. Polymerization with 1,2,4,5-tetrafluorobenzene was not observed, and polymerization of hexafluorobenzene with bisphenol proceeded only if the potassium carbonate-bisphenol ratio was carefully controlled. The polymer condensed from decafluorobiphenyl and bisphenol AF was prepared in 77% yield with an inherent viscosity of 1.01 dL/g. The polymer prepared from the condensation of decafluorobiphenyl with bisphenol A was obtained in 48% yield with an inherent viscosity of 0.28 dL/g. These polymers were very soluble in common organic solvents, formed clear, colorless films, and were thermally stable (> 450-degrees-C by TGA). The fully fluorinated polymer exhibited low water uptake (0.3%) and dielectric constant (2.17). C1 SW TEXAS STATE UNIV,DEPT CHEM,SAN MARCOS,TX 78666. DOW CHEM CO USA,FREEPORT,TX 77541. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RI Irvin, Jennifer/C-7968-2013 OI Irvin, Jennifer/0000-0003-3500-8419 NR 10 TC 40 Z9 41 U1 0 U2 8 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-624X J9 J POLYM SCI POL CHEM JI J. Polym. Sci. Pol. Chem. PD JUL PY 1992 VL 30 IS 8 BP 1675 EP 1679 DI 10.1002/pola.1992.080300820 PG 5 WC Polymer Science SC Polymer Science GA HY833 UT WOS:A1992HY83300020 ER PT J AU KALU, EE WHITE, RE DARCY, EC AF KALU, EE WHITE, RE DARCY, EC TI BULK THERMAL CAPACITY DETERMINATION FOR LI/BCX AND LI/SOCL2 CELLS SO JOURNAL OF POWER SOURCES LA English DT Article AB The bulk heat capacities of Li/BCX and Li/SOCl2 cells were determined at 0 and 100% depth-of-discharge for 2.0 V cut-off voltage, in the temperature range 0 to 60-degrees-C by a method that did not involve the destruction of the cell nor the contact of cell with a liquid. The heat capacity of Li/BCX cell is an important parameter for the design of a thermal control system for Li/BCX batteries. The heat capacities are found to be dependent on state-of-charge - increasing with depth-of-discharge. The Li/BCX DD-cell has a lower heat capacity (0.154 to 0.201 cal/(g K)) than a high rate Li/SOCl2 D-cell (0.191 to 0.221 cal/(g K)). The results obtained by this method compare favorably well with results reported in the literature through other methods. The bulk heat capacities of the cells did not change significantly in the temperature range 0 to 60-degrees-C. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP KALU, EE (reprint author), TEXAS A&M UNIV SYST,DEPT CHEM ENGN,COLL STN,TX 77843, USA. RI Kalu, Egwu/C-6085-2013 NR 6 TC 2 Z9 2 U1 0 U2 4 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD JUL PY 1992 VL 39 IS 2 BP 193 EP 201 DI 10.1016/0378-7753(92)80138-2 PG 9 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA JJ298 UT WOS:A1992JJ29800007 ER PT J AU HOCHSTEIN, JI PATAG, AE KORAKIANITIS, TP CHATO, DJ AF HOCHSTEIN, JI PATAG, AE KORAKIANITIS, TP CHATO, DJ TI PULSED THRUST PROPELLANT REORIENTATION - CONCEPT AND MODELING SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The use of pulsed thrust to optimize the propellant reorientation process is proposed. The ECLIPSE code is used to study the performance of pulsed reorientation in small-scale and full-scale propellant tanks. A dimensional analysis of the process is performed and the resulting dimensionless groups are used to present and correlate the computational predictions of reorientation performance. Based on the results obtained from this study, it is concluded that pulsed thrust reorientation seems to be a feasible technique for optimizing the propellant reorientation process across a wide range of spacecraft, for a variety of missions, for the entire duration of a mission, and with a minimum of hardware design and qualification. C1 WASHINGTON UNIV,MECH ENGN,ST LOUIS,MO 63130. NASA,LEWIS RES CTR,CRYOGEN FLUID MANAGEMENT OFF,CLEVELAND,OH 44135. RP HOCHSTEIN, JI (reprint author), MEMPHIS STATE UNIV,MECH ENGN,MEMPHIS,TN 38152, USA. RI Chato, David/B-2698-2013 OI Chato, David/0000-0003-2990-0646 NR 15 TC 7 Z9 7 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1992 VL 8 IS 4 BP 770 EP 777 DI 10.2514/3.23548 PG 8 WC Engineering, Aerospace SC Engineering GA JC896 UT WOS:A1992JC89600007 ER PT J AU KAZAROFF, JM PAVLI, AJ AF KAZAROFF, JM PAVLI, AJ TI ADVANCED TUBE-BUNDLE ROCKET THRUST CHAMBERS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB An advanced rocket thrust chamber for future space applications is described along with an improved method of fabrication. Included are fabrication demonstrator and test chambers produced by this method. This concept offers the promise of improved cyclic life, reusability, reliability, and performance. The performance is improved because of the enhanced enthalpy extraction. The life, reusability, and reliability is improved because of the enhanced structural compliance inherent in the construction. The method of construction involves the forming of the combustion chamber by a tube-bundle of high-conductivity copper or copper alloy tubes, and the bonding of these tubes by a unique electroforming operation. Further, the method of fabrication reduces chamber complexity by incorporating manifolds, jackets, and structural stiffeners while having the potential for thrust chamber cost and weight reduction. C1 SVERDRUP TECHNOL INC,BROOK PK,OH 44142. RP KAZAROFF, JM (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1992 VL 8 IS 4 BP 786 EP 791 DI 10.2514/3.23550 PG 6 WC Engineering, Aerospace SC Engineering GA JC896 UT WOS:A1992JC89600009 ER PT J AU HUFF, DL AF HUFF, DL TI NUMERICAL-ANALYSIS OF FLOW THROUGH OSCILLATING CASCADE SECTIONS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Analysis techniques are needed for modeling transonic flows in oscillating cascades with real blade geometries. In the present work, a time-marching, finite difference code has been developed for modeling inviscid flow through oscillating cascades by solving the compressible, unsteady Euler equations. The code uses a deforming grid to capture the motion of the airfoils. Results are presented for both flat plates and mildly loaded biconvex airfoils. Comparisons with small-perturbation theory and experimental data are shown. The flat plate comparisons show good qualitative agreement with the theory. Quantitative agreement seems to be at least partially dependent on resolving the leading-edge singularities. Predictions are presented for cases with biconvex airfoils in both subsonic and transonic flows. For certain cases, the results show better agreement with the experimental data than results from the flat plate small-perturbation theory. This suggests that including the effects of loading can be important for the successful prediction of the unsteady flowfield. However, the quantitative agreement is not always as good and is a function of the interblade phase angle and inflow Mach number. Therefore, predictions from the Euler code should be treated with caution and further research is needed to model the unsteady flow for general cases, particularly for super-resonant flows. RP HUFF, DL (reprint author), NASA,LEWIS RES CTR,PROPELLER & ACOUST TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 10 TC 9 Z9 9 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1992 VL 8 IS 4 BP 815 EP 822 DI 10.2514/3.23554 PG 8 WC Engineering, Aerospace SC Engineering GA JC896 UT WOS:A1992JC89600013 ER PT J AU CHYU, WJ HOWE, GW SHIH, TIP AF CHYU, WJ HOWE, GW SHIH, TIP TI BLEED BOUNDARY-CONDITIONS FOR NUMERICALLY SIMULATED MIXED-COMPRESSION SUPERSONIC INLET FLOW SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A numerical study was performed to investigate boundary conditions for bleed openings that are needed in the numerical simulation of critical now through turbojet inlets with bleed. Nine different boundary conditions (BCs) were devised and examined. Of the BCs examined, three were able to stabilize the terminal shock near the inlet's throat. This numerical study was based on the ensemble-averaged, unsteady, three-dimensional, compressible Navier-Stokes equations closed by the Baldwin-Lomax algebraic turbulence model. Solutions to the Navier-Stokes equations were obtained by using a hybrid implicit-explicit method (Beam and Warming/MacCormack). The multiblock grid system used in the solution procedure was generated by solving a set of elliptic partial differential equations. Solutions obtained were compared with available experimental data. C1 CARNEGIE MELLON UNIV,DEPT MECH ENGN,PITTSBURGH,PA 15213. RP CHYU, WJ (reprint author), NASA,AMES RES CTR,FAC SUMMER,APPL AERODYNAM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 19 TC 10 Z9 10 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1992 VL 8 IS 4 BP 862 EP 868 DI 10.2514/3.23561 PG 7 WC Engineering, Aerospace SC Engineering GA JC896 UT WOS:A1992JC89600020 ER PT J AU UNDERWOOD, ML OCONNOR, D WILLIAMS, RM JEFFRIESNAKAMURA, B RYAN, MA BANKSTON, CP AF UNDERWOOD, ML OCONNOR, D WILLIAMS, RM JEFFRIESNAKAMURA, B RYAN, MA BANKSTON, CP TI ELECTRODE PERFORMANCE PARAMETERS FOR A RADIOISOTOPE-POWERED AMTEC FOR SPACE POWER APPLICATIONS SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID METAL THERMOELECTRIC CONVERTER; INTERFACIAL IMPEDANCE; TRANSPORT; KINETICS; ALUMINA AB The alkali metal thermoelectric converter (AMTEC) is a device for the direct conversion of heat to electricity. Recently a design of an AMTEC using a radioisotope heat source was described, but the optimum condenser temperature was hotter than the temperatures used in the laboratory to develop the electrode performance model. Now laboratory experiments have confirmed the dependence of two model parameters over a broader range of condenser and electrode temperatures for two candidate electrode compositions. One parameter, the electrochemical exchange current density at the reaction interface, is independent of the condenser temperature, and depends only upon the collision rate of sodium at the reaction zone. The second parameter, a morphological parameter, which measures the mass transport resistance through the electrode, is independent of condenser and electrode temperatures for molybdenum electrodes. For rhodium-tungsten electrodes, however, this parameter increases for decreasing electrode temperature, indicating an activated mass transport mechanism such as surface diffusion. RP UNDERWOOD, ML (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 21 TC 2 Z9 2 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1992 VL 8 IS 4 BP 878 EP 882 DI 10.2514/3.23564 PG 5 WC Engineering, Aerospace SC Engineering GA JC896 UT WOS:A1992JC89600023 ER PT J AU JACOBS, PA ROGERS, RC WEIDNER, EH BITTNER, RD AF JACOBS, PA ROGERS, RC WEIDNER, EH BITTNER, RD TI FLOW ESTABLISHMENT IN A GENERIC SCRAMJET COMBUSTOR SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The establishment of a quasisteady flow in a generic scramjet combustor is studied for the case of a time varying inflow to the combustor. Such transient flow is characteristic of the reflected-shock tunnel and expansion-tube test facilities. Several numerical simulations of hypervelocity flow through a straight-duct combustor with either a side-wall-step fuel injector or a centrally-located strut injector are presented. Comparisons are made between impulsively started but otherwise constant flow conditions (typical of the expansion-tube or tailored operation of the reflected-shock tunnel) and the relaxing flow produced by the undertailored operation of the reflected-shock tunnel. Generally the inviscid flow features, such as the shock pattern and pressure distribution, were unaffected by the time varying inlet conditions and approached steady state in approximately the times indicated by experimental correlations. However, viscous features, such as heat transfer and skin friction, were altered by the relaxing inlet flow conditions. C1 NASA,LANGLEY RES CTR,HUPERSON PROPULS BRANCH,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,HYPERSON TECHNOL OFF,ANALYT SERV & MAT INC,HAMPTON,VA 23665. RP JACOBS, PA (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,MAIL STOP 132C,HAMPTON,VA 23665, USA. NR 23 TC 9 Z9 9 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1992 VL 8 IS 4 BP 890 EP 899 DI 10.2514/3.23566 PG 10 WC Engineering, Aerospace SC Engineering GA JC896 UT WOS:A1992JC89600025 ER PT J AU BOWLES, JV TAUBER, ME ANAGNOST, AJ WHITTAKER, T AF BOWLES, JV TAUBER, ME ANAGNOST, AJ WHITTAKER, T TI PROPELLANT PRODUCTION FROM THE MARTIAN ATMOSPHERE SO JOURNAL OF PROPULSION AND POWER LA English DT Note ID MISSIONS; MARS C1 STANFORD UNIV,STANFORD,CA 94305. STERLING SOFTWARE,PALO ALTO,CA 94303. RP BOWLES, JV (reprint author), NASA,AMES RES CTR,DEPT AERONAUT & ASTRONAUT,MOFFETT FIELD,CA 94035, USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1992 VL 8 IS 4 BP 907 EP 911 DI 10.2514/3.23568 PG 5 WC Engineering, Aerospace SC Engineering GA JC896 UT WOS:A1992JC89600027 ER PT J AU FARLEY, GL SMITH, BT MAIDEN, J AF FARLEY, GL SMITH, BT MAIDEN, J TI COMPRESSION RESPONSE OF THICK LAYER COMPOSITE LAMINATES WITH THROUGH-THE-THICKNESS REINFORCEMENT SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article AB Compression and compression-after-impact (CAI) tests were conducted on seven different AS4-3501-6 [0/90] 0.64-cm thick composite laminates. Four of the seven laminates had through-the-thickness (TTT) reinforcement fibers. Two TTT reinforcement methods, stitching and integral weaving, and two reinforcement fibers, Kevlar and carbon, were used. The remaining three laminates were made without TTT reinforcements and were tested to establish a baseline for comparison with the laminates having TTT reinforcement. Six of the seven laminates consisted of nine thick layers whereas the seventh material was composed of 46 thin plies. The use of thick-layer material has the potential for reducing structural part cost because of the reduced part count (layers of material). The compression strengths of the TTT reinforced laminates were approximately one half those of the materials without TTT reinforcements. However, the CAI strengths of the TTT reinforced materials were approximately twice those of materials without TTT reinforcements. The improvement in CAI strength is due to an increase in interlaminar strength produced by the TTT reinforcement. Stitched laminates had slightly higher compression and CAI strengths than the integrally woven laminates. C1 COLL WILLIAM & MARY,WILLIAMSBURG,VA 23185. TEXT TECHNOL INC,HATBORO,PA 19040. RP FARLEY, GL (reprint author), NASA,LANGLEY RES CTR,USA,AEROSTRUCT DIRECTORATE,AVSCOM,HAMPTON,VA 23665, USA. NR 35 TC 44 Z9 46 U1 1 U2 2 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 0731-6844 J9 J REINF PLAST COMP JI J. Reinf. Plast. Compos. PD JUL PY 1992 VL 11 IS 7 BP 787 EP 810 DI 10.1177/073168449201100705 PG 24 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA JC378 UT WOS:A1992JC37800005 ER PT J AU WATSON, JJ BUSH, HG HEARD, WL LAKE, MS JENSEN, JK WALLSOM, RE PHELPS, JE AF WATSON, JJ BUSH, HG HEARD, WL LAKE, MS JENSEN, JK WALLSOM, RE PHELPS, JE TI MOBILE TRANSPORTER CONCEPT FOR EXTRAVEHICULAR ACTIVITY ASSEMBLY OF FUTURE SPACECRAFT SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This paper details the ground test program for the NASA Langley Research Center mobile transporter concept. The mobile transporter would assist extravehicular activity astronauts in the assembly of the Space Station Freedom. One-g and simulated 0-g (neutral buoyancy) tests were conducted to evaluate the use of the mobile transporter. A three-bay (44 struts) orthogonal tetrahedral truss configuration with a 15-ft square cross section was repeatedly assembled by a single pair of pressure suited test subjects working from the mobile transporter astronaut positioning devices. The average unit assembly time was 28 s/strut. The results of these tests indicate that the use of a mobile transporter for extravehicular activity assembly of a space station size structure is viable and practical. Additionally, the mobile transporter could be used to construct other spacecraft such as the submillimeter astronomical laboratory, space crane, and interplanetary (i.e., Mars and lunar) spacecraft. C1 LOCKHEED ENGN & SCI CO,DEPT STRUCT & MAT,HAMPTON,VA 23666. RP WATSON, JJ (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT STRUCT BRANCH,MAIL STOP 119,HAMPTON,VA 23665, USA. NR 18 TC 3 Z9 3 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1992 VL 29 IS 4 BP 437 EP 443 DI 10.2514/3.25483 PG 7 WC Engineering, Aerospace SC Engineering GA JK341 UT WOS:A1992JK34100003 ER PT J AU CURRAN, FM HAAG, TW AF CURRAN, FM HAAG, TW TI EXTENDED LIFE AND PERFORMANCE-TEST OF A LOW-POWER ARCJET SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB An automated, cyclic life test was performed to demonstrate the reliability and endurance of a low-power dc arcjet thruster. Over 1000 h and 500 on-off cycles were accumulated, which would represent the requirements for about 15 years of on-orbit lifetime. A hydrogen/nitrogen propellant mixture was used to simulate decomposed hydrazine propellant, and the power level was nominally 1.2 kW after the burn-in period. The arcjet operated in a very repeatable fashion from cycle to cycle. The steady-state voltage increased by approximately 6 V over the first 300 h, and then by only 3 V through the remainder of the test. Thrust measurements taken before, during, and after the test verified that the thruster performed in a consistent fashion throughout the test at a specific impulse of 450-460 s. Post-test component evaluation revealed limited erosion on both the anode and cathode. Other thruster components, including graphite seals, appeared undamaged. RP CURRAN, FM (reprint author), NASA,LEWIS RES CTR,DIV SPACE PROPULS TECHNOL,MAIL STOP SPTO-1,CLEVELAND,OH 44135, USA. NR 31 TC 17 Z9 19 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1992 VL 29 IS 4 BP 444 EP 452 DI 10.2514/3.25484 PG 9 WC Engineering, Aerospace SC Engineering GA JK341 UT WOS:A1992JK34100004 ER PT J AU STANLEY, DO UNAL, R JOYNER, CR AF STANLEY, DO UNAL, R JOYNER, CR TI APPLICATION OF TAGUCHI METHODS TO PROPULSION SYSTEM OPTIMIZATION FOR SSTO VEHICLES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The application of advanced technologies to future launch vehicle designs would allow the introduction of a rocket-powered, single-stage-to-orbit (SSTO) launch system early in the next century. For a selected SSTO concept, a dual mixture ratios, staged combustion cycle engine was selected as the baseline propulsion system. A series of parametric trade studies are presented to optimize both a dual mixture ratio engine and a single mixture ratio engine of similar design and technology level. The effect of varying lift-off thrust-to-weight ratio, engine mode transition Mach number, mixture ratios, ares ratios, and chamber pressure values on overall vehicle weight is examined. The sensitivity of the advanced SSTO vehicle to variations in each of these parameters is presented, taking into account the interaction of each of the parameters with each other. This parametric optimization and sensitivity study employs a Taguchi design method. The Taguchi method is an efficient approach for determining near optimum design parameters using orthogonal matrices from design of experiments (DOE) theory. Using orthogonal matrices significantly reduces the number of experimental configurations to be studied. The effectiveness and limitations of the Taguchi method are also discussed. C1 OLD DOMINION UNIV,HAMPTON,VA 23665. PRATT & WHITNEY AIRCRAFT,W PALM BEACH,FL 33410. RP STANLEY, DO (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,MAIL STOP 365,HAMPTON,VA 23665, USA. NR 11 TC 6 Z9 6 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1992 VL 29 IS 4 BP 453 EP 459 DI 10.2514/3.25485 PG 7 WC Engineering, Aerospace SC Engineering GA JK341 UT WOS:A1992JK34100005 ER PT J AU THANAWALA, AA KWATRA, SC JAMALI, MM BUDINGER, J AF THANAWALA, AA KWATRA, SC JAMALI, MM BUDINGER, J TI EFFICIENT DEMULTIPLEXING ALGORITHM FOR NONCONTIGUOUS CARRIERS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A channel separation algorithm for the frequency division multiple access/time division multiplexing (FDMA/TDM) scheme is presented. It is shown that implementation using this algorithm can be wore effective than the fast Fourier transform (FFT) algorithm when only a small number of carriers need to be selected from many, such as satellite Earth terminals. The algorithm is based on polyphase filtering followed by application of a generalized Walsh-Hadamard transform (GWHT). Comparison of the transform technique used in this algorithm with discrete Fourier transform (DFT) and FFT is given. Estimates of the computational rates and power requirements to implement this system are also given. C1 NASA,LEWIS RES CTR,DIV SPACE ELECTR,DIGITAL SYST TECHNOL BRANCH,CLEVELAND,OH 44135. RP THANAWALA, AA (reprint author), UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606, USA. NR 11 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1992 VL 29 IS 4 BP 498 EP 501 DI 10.2514/3.25491 PG 4 WC Engineering, Aerospace SC Engineering GA JK341 UT WOS:A1992JK34100012 ER PT J AU PENZO, PA JOHNSTON, MD AF PENZO, PA JOHNSTON, MD TI MISSION DESIGN FOR AN ORBITING VOLCANO OBSERVATORY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Mission to Planet Earth initiative will require global observation of land, sea, and atmosphere and all associated phenomena over the coming years, perhaps for decades. A major phenomenon playing a major part in Earth's environment is volcanic activity. Orbital observations, including IR, uv, and visible imaging, may be made to monitor many active sites, and eventually increase our understanding of volcanoes and lead to the predictability of eruptions. This paper presents the orbital design and maneuvering capability of a low cost, volcano-observing satellite, flying in low Earth orbit. Major scientific requirements include observing as many as 10-20 active sites, either daily or every 2 or 3 days. Given specific geographic locations of these sites, it is necessary to search the trajectory space for those orbits that maximize overflight opportunities. Also, once the satellite is in orbit, it may be desirable to alter the orbit to fly over other targets of opportunity. These are active areas that are not being monitored, but which give indications of eruption, or have in fact erupted. Multiple impulse orbital maneuvering methods have been developed to minimize propellant usage for these orbital changes. Mission lifetime is assumed to be 2-3 years. RP PENZO, PA (reprint author), JET PROP LAB,DIV SYST,MISSION DESIGN SECT,TECH STAFF,PASADENA,CA 91109, USA. NR 5 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1992 VL 29 IS 4 BP 502 EP 507 DI 10.2514/3.25492 PG 6 WC Engineering, Aerospace SC Engineering GA JK341 UT WOS:A1992JK34100013 ER PT J AU RAMACHANDRAN, N WINTER, CA AF RAMACHANDRAN, N WINTER, CA TI EFFECTS OF G-JITTER AND MARANGONI CONVECTION ON FLOAT ZONES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID LIQUID AB The effects of g-jitter on three liquid zone experiments are numerically investigated. The g-level used in the study is composed of a steady component, characterizing the residual acceleration environment, and a time-varying component, characterizing the g-jitter environment. The time-varying component is comprised of either a sinusoidal or impulse disturbance. The response of both unencapsulated and encapsulated zone configurations are "examined. The results indicate that complex now patterns can arise that significantly modify the heat transfer characteristics of the system. The effects are more pronounced at the lowest frequency investigated (10(-3) HZ), and impulsive accelerations imparted to fluids with large Prandtl numbers were found to have long decay times. Detailed velocity, temperature, average Nusselt number, and temperature sensitivity information are presented for many of the cases investigated. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP RAMACHANDRAN, N (reprint author), UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35812, USA. NR 18 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1992 VL 29 IS 4 BP 514 EP 522 DI 10.2514/3.25494 PG 9 WC Engineering, Aerospace SC Engineering GA JK341 UT WOS:A1992JK34100015 ER PT J AU STANLEY, DO TALAY, TA LEPSCH, RA MORRIS, WD WURSTER, KE AF STANLEY, DO TALAY, TA LEPSCH, RA MORRIS, WD WURSTER, KE TI CONCEPTUAL DESIGN OF A FULLY REUSABLE MANNED LAUNCH SYSTEM SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID VEHICLES AB The conceptual design of a rocket-powered, two-stage fully reusable launch vehicle has been performed as a part of the advanced manned launch system (AMLS) study by NASA. The main goals of the AMLS study are to provide routine, low-cost manned access to space. Technologies and system approaches have been studied that would contribute to significant reductions in operating time and manpower relative to current systems. System and operational characteristics of the two-stage fully reusable vehicle are presented, and the various tools and methods used in the design process are summarized. The results of a series of trade studies performed to examine the effect of varying major vehicle parameters on the reference two-stage fully reusable vehicle are also summarized. RP STANLEY, DO (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE ANAL BRANCH,MAIL STOP 365,HAMPTON,VA 23665, USA. NR 16 TC 4 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1992 VL 29 IS 4 BP 529 EP 537 DI 10.2514/3.25496 PG 9 WC Engineering, Aerospace SC Engineering GA JK341 UT WOS:A1992JK34100017 ER PT J AU REASONER, DL AF REASONER, DL TI CHEMICAL-RELEASE MISSION OF CRRES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The CRRES satellite was a dual-mission spacecraft to perform active experiments in the Earth's magnetosphere and ionosphere and to study the natural space environment and its effects on spacecraft electronics. Here the NASA chemical-release mission is described. The experiments were motivated by the need to address scientific questions in the areas of coupling between the ionosphere and magnetosphere, response of the magnetosphere system to injections of artificial ion clouds, and instabilities and structuring of the ionosphere in response to perturbations. The basic physics and chemistry of chemical-injection experiments are described, and the individual CRRES experiments are detailed. The initial science results from the chemical-release experiments performed to date are 1) demonstration of critical velocity ionization over a narrow range of parameter space; 2) production of diamagnetic cavities by barium and lithium releases over a wide range of parameters; 3) demonstration of the chemical-release technique to study magnetosphere-ionosphere coupling; 4) modification of energetic electron distribution functions with barium injections; 5) stimulation of magnetospheric waves with barium injections; and 6) possible inducement of enhanced auroral activity. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NR 12 TC 15 Z9 15 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1992 VL 29 IS 4 BP 580 EP 584 DI 10.2514/3.25502 PG 5 WC Engineering, Aerospace SC Engineering GA JK341 UT WOS:A1992JK34100025 ER PT J AU GYEKENYESI, JZ BARTOLOTTA, PA AF GYEKENYESI, JZ BARTOLOTTA, PA TI AN EVALUATION OF STRAIN MEASURING DEVICES FOR CERAMIC COMPOSITES SO JOURNAL OF TESTING AND EVALUATION LA English DT Article DE CERAMIC MATRIX COMPOSITES; TENSILE TESTING; HIGH TEMPERATURE; STRAIN MEASUREMENT; SILICON CARBIDE FIBERS; SILICON NITRIDE MATRIX AB A series of tensile tests were conducted on SiC/RBSN composites using different methods of strain measurement. The tests were used to find the optimum strain sensing device for use with continuous fiber reinforced ceramic matrix composites in ambient and high temperature environments. Bonded resistance strain gages were found to offer excellent performance for room temperature tests. The clip-on gage offers the same performance but significantly less time is required for mounting it to the specimen. Low contact force extensometers track the Strain with acceptable results at high specimen temperatures. Silicon carbide rods with knife edges are preferred. The edges must be kept sharp. The strain measuring devices should be mounted on the flat side of the specimen. This is in contrast to mounting on the rough thickness side. C1 CLEVELAND STATE UNIV,NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 12 TC 4 Z9 4 U1 0 U2 1 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0090-3973 J9 J TEST EVAL JI J. Test. Eval. PD JUL PY 1992 VL 20 IS 4 BP 285 EP 295 PG 11 WC Materials Science, Characterization & Testing SC Materials Science GA JY513 UT WOS:A1992JY51300006 ER PT J AU TISCHLER, MB CAUFFMAN, MG AF TISCHLER, MB CAUFFMAN, MG TI FREQUENCY-RESPONSE METHOD FOR ROTORCRAFT SYSTEM-IDENTIFICATION - FLIGHT APPLICATIONS TO BO-105 COUPLED ROTOR FUSELAGE DYNAMICS SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB A comprehensive frequency-response method for rotorcraft system identification is presented. The overall concept is to 1) extract a complete set of non-parametric input-to-output frequency responses that fully characterizes the coupled helicopter dynamics, and 2) conduct a nonlinear search for a state-space model that matches the frequency-response data set. Each major element of the procedure is reviewed. A new method for combining the results of multi-input frequency-response analyses obtained from a range of spectral windows into a single optimized response is presented. This method eliminates the need for manual optimization of windows and significantly improves the dynamic range and accuracy of the identified frequency-responses relative to single window methods. An integrated user-oriented software package for the frequency-response method is described: Comprehensive Identification from FrEquency Responses (CIFER). CIFER is used to identify a 9-DOF hybrid model of the DLR BO 105 dynamics from flight test data at 80 knots. The identified model includes coupled body/rotor-flapping and lead-lag dynamics, and is accurate to 30 rad/sec. The 9-DOF results are compared with 6-DOF (quasi-steady) identification results. An application of the model to flight control design shows that the maximum roll rate gain is limited by the destabilization of the lead-lag dynamics. C1 STERLING SOFTWARE,PALO ALTO,CA. RP TISCHLER, MB (reprint author), USA,AVIAT RES & TECHNOL ACT,AMES RES CTR,AEROFLIGHTDYNAM DIRECTORATE,MOFFETT FIELD,CA 94035, USA. NR 27 TC 61 Z9 67 U1 0 U2 3 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1992 VL 37 IS 3 BP 3 EP 17 PG 15 WC Engineering, Aerospace SC Engineering GA JH133 UT WOS:A1992JH13300001 ER PT J AU FARLEY, GL WOLTERMAN, RL KENNEDY, JM AF FARLEY, GL WOLTERMAN, RL KENNEDY, JM TI THE EFFECTS OF CRUSHING SURFACE-ROUGHNESS ON THE CRUSHING CHARACTERISTICS OF COMPOSITE TUBES SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB The effects of crushing surface roughness on the energy-absorption capability of graphite and glass-epoxy composite tubes were investigated. Fifty different combinations of fiber, matrix, and specimen ply orientation were evaluated. Two different crushing surface roughnesses were used in this investigation. Crushing surface significantly influences the energy-absorption capability only of tubes that crush in the lamina bending crushing mode; tubes that crush in other modes are not influenced because their lamina bundles do not slide against the crushing surface. Those tubes that crush in the lamina bending mode can achieve higher, lower, or no change in energy-absorption capability as crushing surface roughness increases. If the fiber failure strain of tubes that crush in the lamina bending crushing mode exceeds the matrix failure strain then the energy-absorption capability increases as crushing surface roughness increases. However, if the matrix failure strain exceeds the fiber failure strain then the energy-absorption capability increases as crushing surface roughness decreases. Energy-absorption capability is uninfluenced by crushing surface roughness for tubes that have equal fiber and matrix failure strains. C1 CLEMSON UNIV,DEPT MECH ENGN,CLEMSON,SC 29631. RP FARLEY, GL (reprint author), NASA,LANGLEY RES CTR,AEROSTRUCT DIRECTORATE,HAMPTON,VA 23665, USA. NR 31 TC 6 Z9 6 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1992 VL 37 IS 3 BP 53 EP 60 PG 8 WC Engineering, Aerospace SC Engineering GA JH133 UT WOS:A1992JH13300005 ER PT J AU DESAI, PN BUGLIA, JJ AF DESAI, PN BUGLIA, JJ TI DETERMINING MARS PARKING ORBITS WHICH ENSURE INPLANE ARRIVAL AND DEPARTURE BURNS SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB For a Mars mission, the selection of the Mars parking orbit can greatly influence the overall initial mass of an interplanetary vehicle in low-Earth orbit. If chosen arbitrarily, the selection of the parking orbit can produce a misleading estimate of the mass of the interplanetary vehicle. As a result, serious consideration must be given to the proper selection of the parking orbit. The objective of this study is to develop a numerical method to find suitable Mars parking orbits. In this method, the planes associated with the arrival and departure hyperbolic asymptotes and the parking orbit are considered, along with the precession effects caused by the oblateness of Mars, in the determination of appropriate parking orbits. Hence, actual approach and departure geometries of the parking orbit are analyzed in obtaining the arrival orbital plane. This orbital plane, which contains the arrival asymptote, precesses through the stay time to the plane which also contains the departure asymptote. Thus, the parking orbit is coplanar with the respective asymptote at both arrival and departure. As a result, only in-plane burns are required at both Mars arrival and departure. Therefore, the need for a plane change at Mars departure to achieve the proper velocity vector for Earth return is eliminated. The present method requires very little computation time in determining the set of all the possible inclinations and right ascensions of the ascending nodes for the orbital planes at Mars arrival. The solutions obtained from this method can then be used as a very good first estimate for numerically integrating the entire Mars mission to produce a more accurate simulation and determination of the initial LEO mass of an interplanetary vehicle. C1 FLIGHT MECH & CONTROL INC,HAMPTON,VA. RP DESAI, PN (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 7 TC 3 Z9 3 U1 0 U2 1 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD JUL-SEP PY 1992 VL 40 IS 3 BP 335 EP 349 PG 15 WC Engineering, Aerospace SC Engineering GA JW859 UT WOS:A1992JW85900003 ER PT J AU LEWIS, GD TAYLOR, AH JACOBSON, RA ROTH, DC REIDEL, JE SYNNOTT, SP RYNE, MS AF LEWIS, GD TAYLOR, AH JACOBSON, RA ROTH, DC REIDEL, JE SYNNOTT, SP RYNE, MS TI VOYAGER 2 ORBIT DETERMINATION AT NEPTUNE SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB In August 1989 the Voyager 2 spacecraft encountered the planet Neptune and its major satellite Triton. Numerous science observations were performed by the spacecraft during the encounter. Precise knowledge of the trajectory of the spacecraft relative to the Neptunian system was essential to ensure successful observation of the planet, satellites, and associated phenomena by the spacecraft during the flyby, and to perform trajectory control necessary to achieve mission objectives. Determination of the orbit of Voyager 2 with respect to the Neptunian system was accomplished by the use of radiometric Doppler, range and VLBI observations of the spacecraft in combination with spacecraft-based optical observations of Neptune, Triton, Nereid and the Voyager-discovered satellite 1989N1. These data types were used in a new version of the JPL Orbit Determination Program to determine the orbit of the spacecraft as well as Neptunian system ephemerides and dynamical parameters, resulting in accurate delivery of the spacecraft to targeted conditions at Neptune and Triton. This paper presents a review of orbit determination goals, procedures and results obtained during the Voyager 2 encounter with Neptune. Also presented is a summary of some salient results obtained in the second of two reconstructions of the encounter trajectory. RP LEWIS, GD (reprint author), JET PROP LAB,NAVIGAT SYST SECT,PASADENA,CA 91109, USA. NR 20 TC 1 Z9 1 U1 0 U2 1 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD JUL-SEP PY 1992 VL 40 IS 3 BP 369 EP 406 PG 38 WC Engineering, Aerospace SC Engineering GA JW859 UT WOS:A1992JW85900005 ER PT J AU GELLER, MA NASH, ER WU, MF ROSENFIELD, JE AF GELLER, MA NASH, ER WU, MF ROSENFIELD, JE TI RESIDUAL CIRCULATIONS CALCULATED FROM SATELLITE DATA - THEIR RELATIONS TO OBSERVED TEMPERATURE AND OZONE DISTRIBUTIONS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID DIABATIC CIRCULATION; PLANETARY-WAVES; MIDDLE ATMOSPHERE; MODEL; PERTURBATIONS; SENSITIVITY; COMPUTATION; TRANSPORT; NORTHERN; RATES AB Monthly mean residual circulations were calculated from eight years of satellite data. The diabatic circulation is usually found to give a good approximation to the residual circulation, but this is not always the case. In particular, an example is shown at 60-degrees-S and 30 mb where the diabatic and residual circulations show very different annual variations. Correlations between the vertical component of the residual circulation and temperature and ozone were computed. They indicate that yearly variations of temperatures in the tropics are under dynamical control while at higher latitudes they are under radiative control, except during stratospheric warmings. Interannual variations in seasonal mean temperatures are shown to be under dynamical control everywhere. Correlations between the interannual variations in the seasonal means of the vertical component of the residual circulation and ozone mixing ratios are consistent with what would be expected from the ozone variations being due to differences in the ozone transport, although transport effects cannot easily be distinguished from photochemical effects above the altitude of the ozone mixing ratio peak. Finally, variations in total ozone are examined in comparison with residual circulations variations. A one to two month phase lag is seen in the annual variation in the total ozone at 60-degrees-N with respect to the maximum downward residual motions. This phase lag is greater at 60-degrees-N than at 60-degrees-S. There is evidence at 60-degrees-S of a greater downward trend in the mean zonal ozone maxima than there is in the minima. A decreasing trend in the maximum descending motion is seen to accompany the ozone trend at 60-degrees-S. C1 APPL RES CORP,LANDOVER,MD. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP GELLER, MA (reprint author), SUNY STONY BROOK,INST TERR & PLANETARY ATMOSPHERES,STONY BROOK,NY 11794, USA. NR 20 TC 9 Z9 10 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JUL 1 PY 1992 VL 49 IS 13 BP 1127 EP 1137 DI 10.1175/1520-0469(1992)049<1127:RCCFSD>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JC634 UT WOS:A1992JC63400006 ER PT J AU ABRAMS, EM AF ABRAMS, EM TI IMPLEMENTATION OF THE TOMS CONTAMINATION CONTROL REQUIREMENTS IN THE FORMER USSR SO JOURNAL OF THE IES LA English DT Article DE CONTAMINATION; CLEANROOM; AEROSPACE; SPACE; SPACECRAFT; COMMONWEALTH OF INDEPENDENT STATES; RUSSIA; SOVIET UNION; OZONE; TOMS; METEOR-3 AB The American Total Ozone Mapping Spectrometer (TOMS) was integrated with the Russian Meteor-3 spacecraft and launched on August 15, 1991. Although the TOMS instrument was sensitive to both particulate and molecular contamination, the program for Meteor-3 had not formerly addressed contamination control in ground operations. In order to accommodate the TOMS cleanliness requirements, a contamination control program was successfully established from inception at both the Meteor-3 spacecraft plant near Moscow and at the launch site in Plesetsk. RP ABRAMS, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU INST ENVIRONMENTAL SCI PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 SN 1052-2883 J9 J IES JI J. IES PD JUL-AUG PY 1992 VL 35 IS 4 BP 19 EP 29 PG 11 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA JK445 UT WOS:A1992JK44500004 ER PT J AU CARLSON, AB HASSAN, HA AF CARLSON, AB HASSAN, HA TI DIRECT SIMULATION OF REENTRY FLOWS WITH IONIZATION SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID ELECTRON-IMPACT; EXCITATION AB The Direct Simulation Monte Carlo (DSMC) method is applied in this paper to the study of rarefied, hypersonic, re-entry flows. The assumptions and simplifications involved with the treatment of ionization, free electrons, and the electric field are investigated. A new method is presented for the calculation of the electric field and handling of charged particles with DSMC. In addition, a two-step model for electron impact ionization is implemented. The flowfield representing a 10-km/s shock at an altitude of 65 km is calculated. The effects of the new modeling techniques on the calculation results are presented and discussed. C1 NASA, LANGLEY RES CTR, DIV SPACE SYST, AEROTHERMODYNAM BRANCH, HAMPTON, VA 23665 USA. N CAROLINA STATE UNIV, DEPT MECH & AEROSP SCI, RALEIGH, NC 27695 USA. NR 14 TC 12 Z9 12 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1992 VL 6 IS 3 BP 400 EP 404 DI 10.2514/3.374 PG 5 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JQ546 UT WOS:A1992JQ54600003 ER PT J AU PALMER, G AF PALMER, G TI THERMOCHEMICAL NONEQUILIBRIUM-FLOW COMPUTATIONS OF FLOW AROUND THE AEROASSIST FLIGHT EXPERIMENT SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A three-dimensional explicit, finite rate, shock-capturing, numerical algorithm is used to calculate thermochemical nonequilibrium flowfields about the Aeroassist Flight Experiment (AFE) vehicle at one or its flight trajectory points. The governing equations are expressed in cylindrical coordinates to alleviate perturbations in solution along the three-dimensional grid singular fine. The full Navier-Stokes equations and an 11-species chemical model with the latest reaction rates are incorporated into the code. Pressure, heat transfer, and temperature data are presented. C1 NASA, AMES RES CTR, AEROTHERMODYNAM BRANCH, MOFFETT FIELD, CA 94035 USA. NR 14 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1992 VL 6 IS 3 BP 405 EP 411 DI 10.2514/3.375 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JQ546 UT WOS:A1992JQ54600004 ER PT J AU HARTUNG, LC MITCHELTREE, RA GNOFFO, PA AF HARTUNG, LC MITCHELTREE, RA GNOFFO, PA TI STAGNATION POINT NONEQUILIBRIUM RADIATIVE HEATING AND THE INFLUENCE OF ENERGY EXCHANGE MODELS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A nonequilibrium radiative heating prediction method has been used to evaluate several energy exchange models used in nonequilibrium computational fluid dynamics methods. The radiative heating measurements from the FIRE II flight experiment supply an experimental benchmark against which different formulations for these exchange models can be judged. The models that predict the lowest radiative heating are found to give the best agreement with the flight data. Examination of the spectral distribution of radiation indicates that despite close agreement of the total radiation, many of the models examined predict excessive molecular radiation. It is suggested that a study of the nonequilibrium chemical kinetics may lead to a correction for this problem. C1 NASA, LANGLEY RES CTR, AEROTHERMODYNAM BRANCH, HAMPTON, VA 23665 USA. NR 15 TC 6 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1992 VL 6 IS 3 BP 412 EP 418 DI 10.2514/3.376 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JQ546 UT WOS:A1992JQ54600005 ER PT J AU LUMPKIN, FE CHAPMAN, DR AF LUMPKIN, FE CHAPMAN, DR TI ACCURACY OF THE BURNETT EQUATIONS FOR HYPERSONIC REAL-GAS FLOWS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB The Burnett equations have long been proposed as an alternative to the Navier-Stokes equations for flows exhibiting translational nonequilibrium. However, Burnett solutions for hypersonic flows have until recently been unattainable. Burnett solutions of normal shock-wave structure are presented for four gases: two purely theoretical gases, Maxwellian and hard-sphere, and two real gases, argon and nitrogen. For the theoretical gases, solutions are obtained for Mach numbers from 1.1 to 50, and, for the real gases, solutions range from Mach 1.1 to Mach 11. These Burnett solutions are compared with Direct Simulation Monte Carlo (DSMC) solutions, with Navier-Stokes solutions, and, for the real gases, with experimental data. Experimental data and DSMC solutions represent the assumed correct solution, while Burnett and Navier-Stokes solutions represent continuum approximations. For the three monatomic gases, Burnett solutions are significantly more accurate than Navier-Stokes solutions. For nitrogen, fundamentally different solutions are obtained since rotational nonequilibrium must be included. For this diatomic case, the Burnett solutions also are more accurate than the Navier-Stokes solutions, however, best agreement between DSMC, experiment, and Burnett require different values of rotational collision number in the DSMC and Burnett simulations. The Burnett equations thus represent a significant improvement over Navier-Stokes equations for flows exhibiting translational nonequilibrium. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. STANFORD UNIV, DEPT AERONAUT & ASTRONAUT, STANFORD, CA 94305 USA. NR 29 TC 25 Z9 27 U1 1 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1992 VL 6 IS 3 BP 419 EP 425 DI 10.2514/3.377 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JQ546 UT WOS:A1992JQ54600006 ER PT J AU SIEGEL, R AF SIEGEL, R TI BOUNDARY HEAT FLUXES FOR SPECTRAL RADIATION FROM A UNIFORM TEMPERATURE RECTANGULAR MEDIUM SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Note C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 4 TC 5 Z9 5 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1992 VL 6 IS 3 BP 543 EP 545 DI 10.2514/3.56268 PG 3 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JQ546 UT WOS:A1992JQ54600024 ER PT J AU KASSEMI, M CHUNG, BTF AF KASSEMI, M CHUNG, BTF TI COMBINED CONJUGATED HEAT-TRANSFER FROM A SCATTERING MEDIUM SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Note C1 NASA, LEWIS RES CTR, PROC SCI & TECHNOL BRANCH, CLEVELAND, OH 44135 USA. UNIV AKRON, DEPT MECH ENGN, AKRON, OH 44325 USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1992 VL 6 IS 3 BP 548 EP 551 DI 10.2514/3.397 PG 4 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JQ546 UT WOS:A1992JQ54600026 ER PT J AU MILOS, FS AF MILOS, FS TI FLOWFIELD ANALYSIS FOR HIGH-ENTHALPY ARC HEATERS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Note C1 NASA, AMES RES CTR, THERMAL PROTECT MAT BRANCH, MOFFETT FIELD, CA 94035 USA. NASA, AMES RES CTR, ARC JET RES OFF, MOFFETT FIELD, CA 94035 USA. NR 12 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1992 VL 6 IS 3 BP 565 EP 568 DI 10.2514/3.404 PG 4 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JQ546 UT WOS:A1992JQ54600033 ER PT J AU SUN, DC BREWE, DE AF SUN, DC BREWE, DE TI 2 REFERENCE TIME SCALES FOR STUDYING THE DYNAMIC CAVITATION OF LIQUID-FILMS SO JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB Two formulas, one for the characteristic time of filling a void with the vapor of the surrounding liquid, and one of filling the void by diffusion of the dissolved gas in the liquid, are derived. By comparing these time scales with that of the dynamic operation of oil film bearings, it is concluded that the evaporation process is usually fast enough to fill the cavitation bubble with oil vapor, whereas the diffusion process is much too slow for the dissolved air to liberate itself and enter the cavitation bubble. These results imply that the formation of a two phase fluid in dynamically loaded bearings, as often reported in the literature, is caused by air entrainment. They further indicate a way to simplify the treatment of the dynamic problem of bubble evolution. C1 USA AVIAT RES & TECHNOL ACT,AVSCOM,LEWIS RES CTR,PROPULS DIRECTORATE,CLEVELAND,OH 44135. RP SUN, DC (reprint author), SUNY BINGHAMTON,THOMAS J WATSON SCH ENGN & APPL SCI,DEPT MECH & IND ENGN,BINGHAMTON,NY 13902, USA. NR 13 TC 15 Z9 18 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4787 J9 J TRIBOL-T ASME JI J. Tribol.-Trans. ASME PD JUL PY 1992 VL 114 IS 3 BP 612 EP 615 DI 10.1115/1.2920925 PG 4 WC Engineering, Mechanical SC Engineering GA JF353 UT WOS:A1992JF35300041 ER PT J AU MULAC, RA ADAMCZYK, JJ AF MULAC, RA ADAMCZYK, JJ TI THE NUMERICAL-SIMULATION OF A HIGH-SPEED AXIAL-FLOW COMPRESSOR SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL CONGRESS AND EXPOSITION ON GAS TURBINE AND AEROENGINE CY JUN 03-06, 1991 CL ORLANDO, FL AB The advancement of high-speed axial flow multistage compressors is impeded by a lack of detailed flow field information. Recent developments in compressor flow modeling and numerical simulation have the potential to provide needed information in a timely manner. This paper, which consists of two parts, will explore this topic. The first part will address the development of a computer program to solve the viscous form of the average-passage equation system for multistage turbomachinery. Programming issues such as in-core versus out-of-core data storage and CPU utilization (parallelization, vectorization, and chaining) will be addressed. Code performance will be evaluated through the simulation of the first four stages of a five-stage, high-speed, axial flow compressor on a CRAY Y-MP8/8128 computer. The second part will address the flow physics, which can be obtained from the numerical simulation. In particular, an examination of the end-wall flow structure will be made, and its impact on blockage distribution assessed. RP MULAC, RA (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 13 TC 9 Z9 9 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD JUL PY 1992 VL 114 IS 3 BP 517 EP 527 DI 10.1115/1.2929175 PG 11 WC Engineering, Mechanical SC Engineering GA JG057 UT WOS:A1992JG05700006 ER PT J AU HAH, C REID, L AF HAH, C REID, L TI A VISCOUS-FLOW STUDY OF SHOCK-BOUNDARY LAYER INTERACTION, RADIAL TRANSPORT, AND WAKE DEVELOPMENT IN A TRANSONIC COMPRESSOR SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL CONGRESS AND EXPOSITION ON GAS TURBINE AND AEROENGINE CY JUN 03-06, 1991 CL ORLANDO, FL AB A numerical study based on the three-dimensional Reynolds-averaged Navier-Stokes equation has been conducted to investigate the detailed flow physics inside a transonic compressor. Three-dimensional shock structure, shock-boundary layer interaction, flow separation, radial mixing, and wake development are all investigated at design and off-design conditions. Experimental data based on laser anemometer measurements are used to assess the overall quality of the numerical solution. An additional experimental study to investigate end-wall flow with a hot film was conducted, and these results are compared with the numerical results. Detailed comparison with experimental data indicates that the overall features of the three-dimensional shock structure, the shock-boundary layer interaction, and the wake development are all calculated very well in the numerical solution. The numerical results are further analyzed to examine the radial mixing phenomena in the transonic compressor. A thin sheet of particles is injected in the numerical solution upstream of the compressor. The movement of particles is traced with a three-dimensional plotting package. This numerical survey of tracer concentration reveals the fundamental mechanisms of radial transport in this transonic compressor. Strong radially outward flow is observed inside a separated flow region and this outward flow accounts for about 80 percent of the total radial transport. The radially inward flow is mainly due to the traditional secondary flow. RP HAH, C (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 16 TC 10 Z9 10 U1 2 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD JUL PY 1992 VL 114 IS 3 BP 538 EP 547 DI 10.1115/1.2929177 PG 10 WC Engineering, Mechanical SC Engineering GA JG057 UT WOS:A1992JG05700008 ER PT J AU SNYDER, PG XIONG, YM WOOLLAM, JA ALJUMAILY, GA GAGLIARDI, FJ AF SNYDER, PG XIONG, YM WOOLLAM, JA ALJUMAILY, GA GAGLIARDI, FJ TI GRADED REFRACTIVE-INDEX SILICON OXYNITRIDE THIN-FILM CHARACTERIZED BY SPECTROSCOPIC ELLIPSOMETRY SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID ION ASSISTED DEPOSITION; COATINGS AB A graded refractive index silicon oxynitride (SiOxNy) thin film was prepared on a silicon substrate by ion assisted deposition. Spectroscopic ellipsometry (SE) was used to optically analyze the film. The measured SE spectra (2500-8200 angstrom) were analyzed with several fitting models, whose construction was based on an Auger depth profile of the film. In each model, the optical response of SiOxNy was described using the Bruggeman effective medium approximation, by modeling it as a physical mixture of two distinct phases: silicon dioxide and silicon nitride. Grading was modeled by varying the silicon nitride volume fraction with depth below the surface, according to an assumed profile. Fitting results were very sensitive to the profile chosen, which was different for each model. Experimentation with the profile led to a model which produced a remarkably good fit, over the entire spectral range. As a result, the film thickness and its refractive index profile were determined. The index profile determined by SE analysis was found to be consistent with the Auger profile. C1 JET PROP LAB,PASADENA,CA 91109. BARR ASSOCIATES INC,WESTFORD,MA 01886. RP SNYDER, PG (reprint author), UNIV NEBRASKA,CTR MICROELECT & OPT MAT RES,DEPT ELECT ENGN,LINCOLN,NE 68588, USA. NR 16 TC 44 Z9 45 U1 0 U2 6 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 1462 EP 1466 DI 10.1116/1.578266 PN 2 PG 5 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE682 UT WOS:A1992JE68200011 ER PT J AU OUTLAW, RA WU, D DAVIDSON, MR HOFLUND, GB AF OUTLAW, RA WU, D DAVIDSON, MR HOFLUND, GB TI STUDY OF THE OXYGEN-TRANSPORT THROUGH AG(110), AG(POLY), AND AG 2.0 ZR SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID SINGLE-CRYSTAL SURFACES; ADSORPTION; SILVER; CO2 AB The transport of oxygen through high-purity membranes of Ag (110), Ag (poly), Ag (nano), and Ag 2.0 Zr has been studied by an ultrahigh vacuum permeation method over the temperature range of 400-800-degrees-C. The data show that there are substantial deviations from ordinary diffusion-controlled transport. A surface limitation has been confirmed by glow-discharge studies where the upstream O2 supply has been partially converted to atoms, which, for the same temperature and pressure, gave rise to over an order of magnitude increase in transport flux. Further, the addition of 2.0 wt % Zr to the Ag has provided increased dissociative adsorption rates, which, in tum, increased the transport flux by a factor of 2. It was also observed that below a temperature of 630-degrees-C, the diffusivity exhibits an increase in activation energy of over 4 kcal/mol, which has been attributed to trapping of the atomic oxygen and/or kinetic barriers at the surface and subsurface of the vacuum interface. Above 630-degrees-C, the activation barrier decreases to the accepted value of approximately 11 kcal/mol for Ag (poly), consistent with zero concentration at the vacuum interface. C1 OLD DOMINION UNIV,NORFOLK,VA 23508. UNIV FLORIDA,GAINESVILLE,FL 32611. RP OUTLAW, RA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. RI Davidson, Mark/C-1135-2009 NR 18 TC 20 Z9 23 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 1497 EP 1502 DI 10.1116/1.578273 PN 2 PG 6 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE682 UT WOS:A1992JE68200018 ER PT J AU VASQUEZ, RP HUNT, BD FOOTE, MC BAJUK, LJ AF VASQUEZ, RP HUNT, BD FOOTE, MC BAJUK, LJ TI X-RAY PHOTOELECTRON-SPECTROSCOPY CHARACTERIZATION OF A NONSUPERCONDUCTING Y-BA-CU-O SUPERCONDUCTOR NORMAL-METAL SUPERCONDUCTOR BARRIER MATERIAL SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID SINGLE-CRYSTALS; YBA2CU3O7-X; SURFACES; OXYGEN; PHASE AB X-ray photoelectron spectroscopy (XPS) is used to characterize a new nonsuperconducting Y-Ba-Cu-O barrier material which has successfully been used in superconductor-normal-metal-superconductor (SNS) device structures, grown under conditions similar to those reported to yield a cubic phase (c-YBCO). Comparison of the XPS spectra to those obtained from the orthorhombic (o-YBCO) and tetragonal (t-YBCO) phases shows that the barrier material is distinct from either of the previously known phases. The O 1s spectrum from o-YBCO shows a main peak at 528.0 eV associated with Cu-O planes, a clearly defined shoulder at 527.1 eV associated with Cu-O chains, and a peak at 528.7 eV which variable angle measurements show is a surface peak, tentatively assigned to reconstruction of the surface-terminated Cu-O planes. The O 1s spectra from t-YBCO and the YBCO barrier material exhibit single peaks at 528.8 and 528.1 eV, respectively. The valence band of the barrier material is similar to that of o-YBCO, but narrower on the low binding energy side where the Cu 3d-O 2p pi-bonding states from Cu-O chains occur. The lack of features corresponding to Cu-O chains or surface reconstructed Cu-O planes in the data from the YBCO barrier material is consistent with expectations from a previously proposed simple perovskite crystal structure for c-YBCO. RP VASQUEZ, RP (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 17 TC 0 Z9 0 U1 1 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 1511 EP 1513 DI 10.1116/1.578035 PN 2 PG 3 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE682 UT WOS:A1992JE68200021 ER PT J AU ALTEROVITZ, SA SPEIER, HJ SIEG, RM DROTOS, MN DUNNING, JE AF ALTEROVITZ, SA SPEIER, HJ SIEG, RM DROTOS, MN DUNNING, JE TI NEW TECHNIQUE FOR OIL BACKSTREAMING CONTAMINATION MEASUREMENTS SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID SPECTROSCOPIC ELLIPSOMETRY AB Due to the large size and the number of diffusion pumps, space simulation chambers cannot be easily calibrated by the usual test dome method for measuring backstreaming from oil diffusion pumps. In addition, location dependent contamination may be an important parameter of the test. We have measured the backstreaming contamination in the Space Power Facility (SPF) near Sandusky, Ohio, the largest space simulation vacuum test chamber in the U.S.A. We used small size clean silicon wafers as contamination sensors placed at all desired measurement sites. The facility used diffusion pumps with DC 705 oil. The thickness of the contamination oil film was measured using ellipsometry. Since the oil did not wet uniformly the silicon substrate, two analysis models were developed to measure the oil film: (1) continuous, homogeneous film and (2) islands of oil with the islands varying in coverage fraction and height. In both cases, the contamination film refractive index was assumed to be that of DC 705. The second model improved the ellipsometric analysis quality parameter by up to two orders of magnitude, especially for the low coverage cases. Comparison of the two models for our case shows that the continuous film model overestimates the oil volume by < 50%. Absolute numbers for backstreaming are in good agreement with published results for diffusion pumps. Good agreement was also found between the ellipsometric results and measurements done by x-ray photoelectron spectroscopy (XPS) and by scanning electron microscopy (SEM) on samples exposed to the same vacuum runs. C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. MICHIGAN STATE UNIV,E LANSING,MI 48824. RP ALTEROVITZ, SA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 2099 EP 2104 DI 10.1116/1.577989 PN 2 PG 6 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE682 UT WOS:A1992JE68200118 ER PT J AU KENNY, TW KAISER, WJ REYNOLDS, JK PODOSEK, JA ROCKSTAD, HK VOTE, EC WALTMAN, SB AF KENNY, TW KAISER, WJ REYNOLDS, JK PODOSEK, JA ROCKSTAD, HK VOTE, EC WALTMAN, SB TI ELECTRON TUNNEL SENSORS SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID CAPACITIVE PRESSURE SENSOR; SILICON; ACCELEROMETER; MICROSCOPY; NOISE; TRANSDUCER; DETECTOR AB We have used the extreme sensitivity of electron tunneling to variations in electrode separation to construct a novel, compact displacement transducer. Electrostatic forces are used to control the separation between the tunneling electrodes, thereby eliminating the need for piezoelectric actuators. The entire structure is composed of micromachined silicon single crystals. Applications of the tunneling displacement transducer to the measurement of acceleration and infrared signals are discussed. Measurements of acceleration and infrared sensitivity are reported. RP KENNY, TW (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 28 TC 8 Z9 9 U1 2 U2 6 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 2114 EP 2118 DI 10.1116/1.577991 PN 2 PG 5 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE682 UT WOS:A1992JE68200120 ER PT J AU FATHAUER, RW GEORGE, T AF FATHAUER, RW GEORGE, T TI GROWTH-PARAMETERS AFFECTING THE FORMATION OF BURIED COSI2 BY ENDOTAXY OF CO ON SI(111) SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID MOLECULAR-BEAM EPITAXY; SI; LAYERS AB At growth temperatures of almost-equal-to 800-degrees-C, Co deposited on Si (111) diffuses through a Si capping layer and exhibits oriented growth on buried CoSi2 Seeds, a process referred to as endotaxy. This occurs preferentially to surface nucleation of CoSi2 under certain growth conditions. High-quality continuous single-crystal buried silicide layers have been obtained by endotaxy. This requires very low densities of attractive nucleation sites other than the buried seeds. For this reason, use of a silicon buffer layer and a low base pressure in the molecular-beam epitaxy system are found to be essential. Growth conditions required for high-quality layers and problems which result from growth outside these limits are discussed. RP FATHAUER, RW (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 11 TC 2 Z9 2 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 2404 EP 2406 DI 10.1116/1.577974 PN 3 PG 3 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE683 UT WOS:A1992JE68300046 ER PT J AU HERRERAFIERRO, P PEPPER, SV JONES, WR AF HERRERAFIERRO, P PEPPER, SV JONES, WR TI X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF THE STABILITY OF FOMBLIN-Z25 ON THE NATIVE OXIDE OF ALUMINUM SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID PERFLUOROPOLYALKYLETHER OIL; ULTRAHIGH-VACUUM; SURFACES; DEGRADATION; TEMPERATURE; STEEL; FEF3 AB Thin films of Fomblin Z25, a perfluoropolyalkylether lubricant, were vapor deposited onto clean, oxidized aluminum, and sapphire surfaces, and their behavior at different temperatures was studied using x-ray photoelectron spectroscopy and temperature desorption spectroscopy (TDS). It was found that the interfacial fluid molecules decompose on the native oxide at room temperature, and continue to decompose at elevated temperatures, as previous studies had shown to occur on the clean metal. TDS indicated that different degradation mechanisms were operative for clean and oxidized aluminum. On sapphire substrates, no reaction was observed at room temperature. Our conclusion is that the native oxide of aluminum is neither passive nor protective towards Fomblin Z25. At higher temperatures (150-degrees-C) degradation of the polymer on sapphire produced a debris layer at the interface with a chemical composition similar to the one formed on aluminum oxide. Rubbing a Fomblin film on a single crystal sapphire also induced the decomposition of the lubricant in contact with the interface and the formation of a debris layer. RP HERRERAFIERRO, P (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 19 TC 10 Z9 10 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 2746 EP 2751 DI 10.1116/1.577904 PN 3 PG 6 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE683 UT WOS:A1992JE68300106 ER PT J AU JAYNE, DT FATEMI, NS WEIZER, VG AF JAYNE, DT FATEMI, NS WEIZER, VG TI CORE LEVEL X-RAY PHOTOELECTRON-SPECTROSCOPY OF AUXGAY ALLOYS SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID SPECTROMETER TRANSMISSION FUNCTION; AU-GE FILMS; N-TYPE GAAS; XPS AB Five Au-Ga alloys have been studied using x-ray photoelectron spectroscopy as part of the program to determine alloy effects on core level binding energies and identify thin film and bulk compositions of unknown AuxGay alloys. The binding energies and peak intensities of the Au 4f, Ga 2p3/2, Ga 3p3/2, and Ga LMM core levels were determined for pure Au and Ga along with bulk alloy compositions of alpha-Au0.88Ga0.12, beta-Au0.78Ga0.22, gamma-Au9Ga4, AuGa, and AuGa2. These values were determined for surfaces scraped in situ to expose the bulk composition. The Au 4f7/2 binding energies were 83.95 eV for pure Au and 84.4, 84.6, 84.9, 85.2, and 85.5 eV for each of the respective alloys, while the Ga core levels and Auger energy shifted less than 0.3 eV over the range of alloy compositions. These results exhibit the same trend as the previously studied Au-In system and furnish calibration values that allow determination of the composition of unknown alloys. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 16 TC 7 Z9 7 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 2802 EP 2805 DI 10.1116/1.577913 PN 3 PG 4 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE683 UT WOS:A1992JE68300115 ER PT J AU DALINS, I KARIMI, M AF DALINS, I KARIMI, M TI ANGULARLY RESOLVED X-RAY PHOTOELECTRON-SPECTROSCOPY INVESTIGATION OF PTFE AFTER PROLONGED SPACE EXPOSURE SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 38TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY NOV 11-15, 1991 CL SEATTLE, WA SP AMER VACUUM SOC ID XPS; INTERFACES; TOOL AB Monochromatized angularly resolved x-ray photoelectron spectroscopy (ARXPS) was used to study PTFE (Teflon) that had been exposed to an Earth orbital environment for approximately six years. The primary interest of the research is on a very reactive component of this environment (atomic oxygen) which, because of the typical orbital velocities of a spacecraft, impinge on exposed surfaces with 5 eV energy. Generation of such particles in a laboratory is not practical, thus, the atomic oxygen aspect must eventually be resolved in a space flight environment. This presentation deals with the method of analysis, the findings as they pertain to a rather complex carbon, oxygen, and fluorine XPS peak analysis, and the character of the valence bands. An improved bias referencing method, based on ARXPS, will also be demonstrated for evaluating specimen charging effects. It was found that the polymer molecule tends to resist the atomic oxygen attack by reorienting itself, so that the most electronegative CF3 groups are facing the incoming hyperthermal oxygen atoms. The implications of these findings to ground-based laboratory studies will also be discussed. C1 ALABAMA A&M UNIV,NORMAL,AL 35762. RP DALINS, I (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 24 TC 1 Z9 1 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD JUL-AUG PY 1992 VL 10 IS 4 BP 2921 EP 2925 DI 10.1116/1.577730 PN 3 PG 5 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA JE683 UT WOS:A1992JE68300136 ER PT J AU FAUR, M FAUR, M HONECY, F GORADIA, C GORADIA, M JAYNE, D CLARK, R AF FAUR, M FAUR, M HONECY, F GORADIA, C GORADIA, M JAYNE, D CLARK, R TI CLOSED-AMPOULE DIFFUSION OF SULFUR INTO CD-DOPED INP SUBSTRATES - DEPENDENCE OF S PROFILES ON DIFFUSION TEMPERATURE AND TIME SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID P-TYPE INP; OXIDES; XPS AB In order to optimize the fabrication of n+-p InP solar cells made by closed-ampoule diffusion of sulfur into p-InP:Cd substrates, we have investigated the influence of diffusion conditions on sulfur diffusion profiles. We show that S diffusion in InP is dominated by the P vacancy mechanism and is not characterized by a complementary error function as expected for an infinite source diffusion. The S diffusion mechanism in p-InP is qualitatively explained by examining the depth profiles of S, P, and In in the emitter layer and by taking into account the presence and composition of different compounds found to form in the In-P-S-O-Cd system as a result of diffusion. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. CASE WESTERN RESERVE UNIV, CLEVELAND, OH 44105 USA. RP FAUR, M (reprint author), CLEVELAND STATE UNIV, DEPT ELECT ENGN, SPACE PHOTOVOLTA RES CTR, CLEVELAND, OH 44115 USA. NR 25 TC 0 Z9 0 U1 2 U2 2 PU A V S AMER INST PHYSICS PI MELVILLE PA STE 1 NO 1, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747-4502 USA SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD JUL-AUG PY 1992 VL 10 IS 4 BP 1277 EP 1284 DI 10.1116/1.585900 PG 8 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA JJ600 UT WOS:A1992JJ60000004 ER PT J AU KUO, TC WANG, KL ARGHAVANI, R GEORGE, T LIN, TL AF KUO, TC WANG, KL ARGHAVANI, R GEORGE, T LIN, TL TI INTERFACE STOICHIOMETRY DEPENDENCE OF THE SCHOTTKY-BARRIER HEIGHT OF COGA AND GAAS SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID MOLECULAR-BEAM EPITAXY; METAL LAYER; CONTACTS; DIODES; STATES AB The Schottky barrier formation of CoGa on (100)n-GaAs is investigated. CoGa is grown by molecular-beam epitaxy, and the epitaxial orientation is controlled by the initial growth conditions of the GaAs substrate. Schottky diodes with three different phases of CoGa: (100)CoGa, (110)CoGa and mix of (100) and (110)CoGa, are fabricated and Schottky barrier heights are measured by I-V, C-V, and internal photoemission. All these three types of diodes have different values of barrier height, indicating that the mechanisms of the barrier formation for these three phases are different. The plausible mechanisms for the change of the Fermi level pinning position of these phases are discussed. Finally, the temperature dependence of the Schottky barrier height is also examined and the barrier height is found to be constant from 150 to 300 K for all of the phases. C1 JET PROP LAB,PASADENA,CA 91109. RP KUO, TC (reprint author), UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,DEVICE RES LAB,LOS ANGELES,CA 90024, USA. RI Schaff, William/B-5839-2009 NR 23 TC 7 Z9 7 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD JUL-AUG PY 1992 VL 10 IS 4 BP 1923 EP 1927 DI 10.1116/1.586159 PG 5 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA JJ600 UT WOS:A1992JJ60000113 ER PT J AU RICH, DH RAJKUMAR, KC CHEN, L MADHUKAR, A GEORGE, T MASERJIAN, J GRUNTHANER, FJ LARSSON, A AF RICH, DH RAJKUMAR, KC CHEN, L MADHUKAR, A GEORGE, T MASERJIAN, J GRUNTHANER, FJ LARSSON, A TI DEFECTS IN STRAINED IN0.2GA0.8AS/GAAS MULTIPLE QUANTUM-WELLS ON PATTERNED AND UNPATTERNED SUBSTRATES - A NEAR-INFRARED CATHODOLUMINESCENCE STUDY SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID MISFIT DISLOCATIONS; GROWTH; GAAS; PHOTOLUMINESCENCE; SPECTROSCOPY; INXGA1-XAS; REDUCTION; STRIPES; AREA AB The spatial distribution of the long-wavelength luminescence in thick In0.2Ga0.8As/GaAs multiple quantum wells (MQWs) grown on patterned and unpatterned substrates has been investigated using cathodoluminescence (CL) imaging and spectroscopy. By spatially correlating the luminescence arising from the MQW exciton recombination (lambda almost-equal-to 950 nm) with the longer wavelength (1000 less than or similar lambda less than or similar 1200 nm) luminescence arising from the defect-induced recombination, we demonstrate that it is possible to determine the regions of highest film quality in both the mesa and valley regions for growth on patterned GaAs substrates. The present approach enables a judicious determination of the optimal regions to be used for active pixels in InGaAs/GaAs devices. For growth on unpatterned substrates, the CL spectra show defect-induced broad bands between 1000 less than or similar lambda less than or similar 1600 nm. These bands exhibit spatial variations which correlate with the dark line defects (DLDs) observed in the lambda = 950 nm exciton luminescence imaging. Transmission electron microscopy showed that [110]-oriented misfit dislocations occur primarily at the substrate-to-MQW interface. The large spatial variation of the luminescence intensities indicates that the DLDs observed in CL images are caused by the presence of nonradiative recombination centers occurring in the MQW region located above the interface dislocations. This study provides new information describing the origin and nature of DLDs and differs from previous models, which have regarded the electronic nature of dislocation cores as the primary mechanism for inducing DLD radiative contrast in luminescence imaging of strained InGaAs/GaAs. C1 JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. CHALMERS UNIV TECHNOL,DEPT OPTOELECTR & ELECT MEASUREMENTS,S-41296 GOTHENBURG,SWEDEN. RP RICH, DH (reprint author), UNIV SO CALIF,DEPT MAT SCI & ENGN,PHOTON MAT & DEVICES LAB,LOS ANGELES,CA 90089, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 21 TC 4 Z9 4 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD JUL-AUG PY 1992 VL 10 IS 4 BP 1965 EP 1970 DI 10.1116/1.586167 PG 6 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA JJ600 UT WOS:A1992JJ60000121 ER PT J AU PIKE, WT FATHAUER, RW ANDERSON, MS AF PIKE, WT FATHAUER, RW ANDERSON, MS TI SURFACE-MORPHOLOGY OF MOLECULAR-BEAM EPITAXIALLY GROWN SI1-XGEX LAYERS ON (100) AND (110) SI SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID GEXSI1-X AB The surface morphology and dislocation structure of Si1-xGex layers grown on (100) and (110) Si substrates have been investigated using atomic force microscopy, and scanning and transmission electron microscopy. The layers, which have up to a 1.2% lattice mismatch with the substrates, were grown by molecular-beam epitaxy at 550-degrees-C at thicknesses above those required for the introduction of dislocations. Si1-xGex, layers grown on (100) show a crosshatch morphology which is correlated to the underlying misfit dislocation network. Annealing greatly enhances the surface roughness producing a partial islanding growing on the pre-existing crosshatch morphology. On the (110) substrates no annealing is necessary to produce a roughened surface. The roughened surface morphology is analyzed as a strain-reducing growth mode which enables partial relaxation of the near-surface atomic planes. RP PIKE, WT (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 10 TC 10 Z9 10 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD JUL-AUG PY 1992 VL 10 IS 4 BP 1990 EP 1993 DI 10.1116/1.586172 PG 4 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA JJ600 UT WOS:A1992JJ60000126 ER PT J AU BANISH, LD GILMARTIN, WG AF BANISH, LD GILMARTIN, WG TI PATHOLOGICAL FINDINGS IN THE HAWAIIAN MONK SEAL SO JOURNAL OF WILDLIFE DISEASES LA English DT Article DE MONACHUS-SCHAUINSLANDI; MONK SEAL; PATHOLOGY; EMACIATION; PARASITES; TRAUMA; SURVEY AB Postmortem examinations were performed on 45 Hawaiian monk seals (Monachus schauinslandi) collected during field research on the beaches of the Northwestern Hawaiian Islands (USA) from 1981 to 1985. Both males and females of all age groups, perinatal through adult, were examined. Frequent findings included parasites, trauma, cardiovascular disease (congenital and acquired), and respiratory infections. Emaciation was a common condition. All animals except neonates were infected with parasites; infection was severe in several cases. Splenic hematopoiesis was a universal histopathologic finding. Some cases exhibited lesions consistent with renal, gastrointestinal, and toxic disorders; ectopic tissue calcification; gallstones; and ophthalmologic and dental problems. C1 UNIV CALIF DAVIS,VET MED TEACHING HOSP,DEPT MED,DAVIS,CA 95616. RP BANISH, LD (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822, USA. NR 23 TC 17 Z9 19 U1 1 U2 9 PU WILDLIFE DISEASE ASSN, INC PI LAWRENCE PA 810 EAST 10TH ST, LAWRENCE, KS 66044-8897 SN 0090-3558 J9 J WILDLIFE DIS JI J. Wildl. Dis. PD JUL PY 1992 VL 28 IS 3 BP 428 EP 434 PG 7 WC Veterinary Sciences SC Veterinary Sciences GA JF485 UT WOS:A1992JF48500013 PM 1512875 ER PT J AU WHARTON, WW SONDEEN, JL MCBILES, M GRADWOHL, SE WADE, CE CICERI, DP LEHMANN, HG STOTLER, RE HENDERSON, TR WHITAKER, WR LINDBERG, JS AF WHARTON, WW SONDEEN, JL MCBILES, M GRADWOHL, SE WADE, CE CICERI, DP LEHMANN, HG STOTLER, RE HENDERSON, TR WHITAKER, WR LINDBERG, JS TI MEASUREMENT OF GLOMERULAR-FILTRATION RATE IN ICU PATIENTS USING TC-99M-DTPA AND INULIN SO KIDNEY INTERNATIONAL LA English DT Article ID RENAL-DISEASE; CREATININE; INSUFFICIENCY; CLEARANCE; DTPA AB Improved and reliable methods for assessing glomerular filtration rate (GFR) in intensive care patients are needed in light of known deficiencies using creatinine clearance. We compared simultaneous two-hour clearances of inulin (C(In)), creatinine (C(Cr)), and Tc-99m-diethylenetriaminepentaacetic acid (C(DTPA)) in 18 medical or surgical intensive care patients (range, 49 to 92 years old) with blood urea nitrogen (BUN) levels >17.9 mmol/liter (0.5 mg/ml), serum creatinine levels >150-mu-mol/liter (0.02 mg/ml). or estimated Cockcroft clearance <60 ml/min. Patients had severe renal dysfunction with average GFR of 35 ml/min (range. 2 to 69 ml/min). C(DTPA) and C(Cr) correlated significantly with C(In), although C(DTPA) tended to provide a closer approximation. Cockcroft clearance (32 +/- 4 ml/min) was grossly similar to C(DTPA) and C(In) and correlated significantly. especially when weight was calculated using actual as opposed to ideal body weight. In a subset of 13 patients with C(In) <30 ml/min. only C(DTPA) was significantly correlated with C(In). In patients in the intensive care unit, C(DTPA) provides a rapid. accurate. and inexpensive clinical assessment of GFR, even at very low GFRs. C1 ALTON OCHSNER MED FDN & OCHSNER CLIN,DEPT INTERNAL MED,NEPHROL SECT,NEW ORLEANS,LA 70121. LETTERMAN ARMY MED CTR,DEPT MED,NUCL MED SERV,SAN FRANCISCO,CA 94129. LETTERMAN ARMY MED CTR,DEPT RADIOL,SAN FRANCISCO,CA 94129. LETTERMAN ARMY MED CTR,PHARMACOL SERV,SAN FRANCISCO,CA 94129. LETTERMAN ARMY INST RES,DIV MIL TRAUMA RES,SAN FRANCISCO,CA 94129. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 16 TC 17 Z9 17 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 SN 0085-2538 J9 KIDNEY INT JI Kidney Int. PD JUL PY 1992 VL 42 IS 1 BP 174 EP 178 DI 10.1038/ki.1992.275 PG 5 WC Urology & Nephrology SC Urology & Nephrology GA HY762 UT WOS:A1992HY76200023 PM 1635347 ER PT J AU VITALIANO, JJ ZDANOWICZ, VS AF VITALIANO, JJ ZDANOWICZ, VS TI TRACE-METALS IN EGGS OF WINTER FLOUNDER FROM BOSTON HARBOR, A CONTAMINATED NORTH-AMERICAN ESTUARY SO MARINE POLLUTION BULLETIN LA English DT Note AB In 1987, the effects of contaminant levels in Boston Harbor, Massachusetts on the reproductive success of winter flounder were studied. As part of the study, the concentrations of 15 trace metals in laboratory-spawned eggs from adult winter flounder, taken from two stations in Boston Harbor, were measured using atomic absorption spectrophotometry. Trace metal concentrations in the eggs were low. There were no statistically significant differences between the two stations in the concentrations of any trace metal in the eggs. However, two fish captured from the Deer Island station had concentrations of cadmium in their eggs that were the highest reported for a flounder species to date. The concentrations of trace metals in eggs of winter flounder from Boston Harbor were similar to eggs of flounder species from other estuaries that exhibited different levels of habitat contamination. This suggests that differences in habitat contamination are not necessarily reflected in metal concentrations in laboratory spawned eggs. RP NOAA, NATL MARINE FISHERIES SERV, SANDY HOOK LAB, HIGHLANDS, NJ 07732 USA. NR 9 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 0025-326X EI 1879-3363 J9 MAR POLLUT BULL JI Mar. Pollut. Bull. PD JUL PY 1992 VL 24 IS 7 BP 364 EP 367 DI 10.1016/0025-326X(92)90374-F PG 4 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA JH502 UT WOS:A1992JH50200009 ER PT J AU REVIERE, RD NOEBE, RD OLIVER, BF AF REVIERE, RD NOEBE, RD OLIVER, BF TI PROCESSING, MICROSTRUCTURE AND LOW-TEMPERATURE PROPERTIES OF DIRECTIONALLY SOLIDIFIED NIAL NIALNB ALLOYS SO MATERIALS LETTERS LA English DT Article AB A containerless levitation zone processing technique was used to directionally solidify two Ni-Al-Nb alloys in an attempt to improve the fracture strength and ductility of creep resistant, NiAl-based intermetallics through microstructural control. Directional-solidification processing was successful in producing aligned in-situ composite microstructures, while eliminating grain boundaries. One alloy consisted of an aligned eutectic microstructure composed of the intermetallic phases NiAl and NiAlNb while the other alloy consisted of globular NiAl dendrites surrounded by aligned eutectic regions. However, both alloys were brittle at room temperature and exhibited relatively low fracture strengths. The lack of ductility in these alloys was attributed to the high hardness and low toughness of both the NiAl and NiAlNb constituent phases. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP REVIERE, RD (reprint author), UNIV TENNESSEE,DEPT MAT SCI,KNOXVILLE,TN 37996, USA. NR 19 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-577X J9 MATER LETT JI Mater. Lett. PD JUL PY 1992 VL 14 IS 2-3 BP 149 EP 155 DI 10.1016/0167-577X(92)90194-O PG 7 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA JE954 UT WOS:A1992JE95400016 ER PT J AU TATRO, DL DUDLEY, GA CONVERTINO, VA AF TATRO, DL DUDLEY, GA CONVERTINO, VA TI CAROTID-CARDIAC BAROREFLEX RESPONSE AND LBNP TOLERANCE FOLLOWING RESISTANCE TRAINING SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Article DE BLOOD PRESSURE; LOWER BODY NEGATIVE PRESSURE; ORTHOSTATISM; NECK CHAMBER; LIMB COMPLIANCE; HEART RATE VARIABILITY ID BODY NEGATIVE-PRESSURE; HEART-RATE; SINUS ARRHYTHMIA; REFLEX; STRENGTH; MEN; ENDURANCE; SIZE AB The purpose of this study was to examine the effect of lower body resistance training on cardiovascular control mechanisms and blood pressure maintenance during an orthostatic challenge. Lower body negative pressure (LBNP) tolerance, carotid-cardiac baroreflex function (using neck chamber pressure), and calf compliance were measured in eight healthy males before and after 19 wk of knee extension and leg press training. Resistance training sessions consisted of four or five sets of 6-12 repetitions of each exercise, performed two times per week. Training increased strength 25 +/- 3 (SE)% (P = 0.0003) and 31 +/- 6% (P = 0.0004), respectively, for the leg press and knee extension exercises. Average fiber size in biopsy samples of m. vastus lateralis increased 21 +/- 5% (P = 0.0014). Resistance training had no significant effect on LBNP tolerance. However, calf compliance decreased in five of the seven subjects measured, with the group average changing from 4.4 +/- 0.6 ml.mm Hg-1 to 3.9 +/- 0.3 ml.mm Hg-1 (P = 0.3826). The stimulus-response relationship of the carotid-cardiac baroreflex response shifted to the left on the carotid pressure axis as indicated by a reduction of 6 mm Hg in baseline systolic blood pressure (P = 0.0471). In addition. maximum slope increased from 5.4 +/- 1.3 ms.mm Hg-1 before training to 6.6 +/- 1.6 ms.mm Hg-1 after training (P = 0.0141). Our results suggest the possibility that high resistance, lower extremity exercise training can cause a chronic increase in sensitivity and resetting of the carotid-cardiac baroreflex. However, change in carotid-cardiac baroreflex function did not prove advantageous during a hypotensive challenge induced by LBNP. These findings may reflect the failure of the specific resistance training stimulus employed in our study to induce changes in other mechanisms important to blood pressure regulation. C1 NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. BIONET CORP,KENNEDY SPACE CTR,FL 32899. NR 33 TC 27 Z9 27 U1 1 U2 1 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD JUL PY 1992 VL 24 IS 7 BP 789 EP 796 PG 8 WC Sport Sciences SC Sport Sciences GA JC413 UT WOS:A1992JC41300009 PM 1501564 ER PT J AU BORG, J BIBRING, JP BUNCH, TE DIBROZOLO, FR VASSENT, B AF BORG, J BIBRING, JP BUNCH, TE DIBROZOLO, FR VASSENT, B TI FURTHER ANALYSIS OF MICROMETEOROID REMNANTS SO METEORITICS LA English DT Meeting Abstract C1 INST ADV STUDIES,F-91405 ORSAY,FRANCE. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. CHARLES EVANS & ASSOCIATES,REDWOOD CITY,CA 94063. CTR SPECTROMETRIE NUCL & SPECTROMETRIE MASSE,F-91405 ORSAY,FRANCE. NR 3 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 205 EP 206 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900020 ER PT J AU BROADHURST, CL MUMMA, MJ AF BROADHURST, CL MUMMA, MJ TI EXPERIMENTAL INVESTIGATION OF NUCLEAR-SPIN CONVERSION IN INTERSTELLAR PRECOMETARY ICES SO METEORITICS LA English DT Meeting Abstract ID COMET C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RI mumma, michael/I-2764-2013 NR 4 TC 1 Z9 1 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 207 EP 208 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900024 ER PT J AU FLYNN, GJ SUTTON, SR KELLER, LP THOMAS, KL BAJT, S AF FLYNN, GJ SUTTON, SR KELLER, LP THOMAS, KL BAJT, S TI TRACE-ELEMENTS IN CHONDRITIC SPHERES FROM THE STRATOSPHERE - IMPLICATIONS FOR THE NI-DEPLETIONS IN POLAR MICROMETEORITES SO METEORITICS LA English DT Meeting Abstract ID DUST C1 SUNY COLL PLATTSBURGH,DEPT PHYS,PLATTSBURGH,NY 12901. UNIV CHICAGO,DEPT GEOPHYS SCI,CHICAGO,IL 60637. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NASA,HOUSTON,TX 77058. RI Bajt, Sasa/G-2228-2010 NR 8 TC 1 Z9 1 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 221 EP 221 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900052 ER PT J AU HARPER, CL WEISMANN, H NYQUIST, LE AF HARPER, CL WEISMANN, H NYQUIST, LE TI THE SEARCH FOR CS-135 IN THE EARLY SOLAR-SYSTEM - VERY HIGH-PRECISION MEASUREMENTS OF BARIUM ISOTOPES IN BULK ALLENDE AND REFRACTORY INCLUSIONS SO METEORITICS LA English DT Meeting Abstract C1 HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 5 TC 17 Z9 18 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 230 EP 231 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900072 ER PT J AU JONES, JH HART, SR BENJAMIN, TM AF JONES, JH HART, SR BENJAMIN, TM TI EXPERIMENTAL PARTITIONING OF ELEMENTS RELATED TO IRON METEORITE CHRONOLOGIES - AG, AU, MO, NI, PB, PD, AND TL SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. WOODS HOLE OCEANOG INST,WOODS HOLE,MA 02543. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. NR 6 TC 0 Z9 0 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 239 EP 240 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900090 ER PT J AU JONES, JH JUREWICZ, AJG MITTLEFEHLDT, DW AF JONES, JH JUREWICZ, AJG MITTLEFEHLDT, DW TI FURTHER EXPERIMENTAL CONSTRAINTS ON THE ORIGIN OF EUCRITES SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LOCKHEED ESC,HOUSTON,TX 77258. NR 5 TC 0 Z9 0 U1 1 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 240 EP 240 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900091 ER PT J AU KEITH, JE HEYDEGGER, HR AF KEITH, JE HEYDEGGER, HR TI THE PREDICTION OF THE SATURATED ACTIVITY OF AL-26 IN NON-ANTARCTIC STONY METEORITES FROM THEIR CHEMICAL-COMPOSITIONS SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. PURDUE UNIV CALUMET,HAMMOND,IN 46323. NR 4 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 241 EP 242 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900094 ER PT J AU KELLER, LP TREIMAN, AH WENTWORTH, SJ AF KELLER, LP TREIMAN, AH WENTWORTH, SJ TI SHOCK EFFECTS IN THE SHERGOTTITE LEW88516 - OPTICAL AND ELECTRON-MICROSCOPE OBSERVATIONS SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LOCKHEED,HOUSTON,TX 77058. NR 4 TC 5 Z9 5 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 242 EP 242 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900095 ER PT J AU LINDSTROM, DJ KLOCK, W AF LINDSTROM, DJ KLOCK, W TI ANALYSES OF 24 UNMELTED ANTARCTIC MICROMETEORITES BY INSTRUMENTAL NEUTRON-ACTIVATION ANALYSIS SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV MUNSTER,INST PLANETOL,W-4400 MUNSTER,GERMANY. NR 8 TC 4 Z9 4 U1 1 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 250 EP 250 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900113 ER PT J AU LINDSTROM, MM MITTLEFEHLDT, DW AF LINDSTROM, MM MITTLEFEHLDT, DW TI A GEOCHEMICAL STUDY OF RUSSIAN EUCRITES AND HOWARDITES SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,CURATORS OFF,HOUSTON,TX 77058. LOCKHEED ESC,HOUSTON,TX 77058. NR 0 TC 4 Z9 4 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 250 EP 250 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900114 ER PT J AU MARTINEZ, R ZOLENSKY, M RIOS, EMD AF MARTINEZ, R ZOLENSKY, M RIOS, EMD TI NEW L-CHONDRITES FROM ANTOFAGASTA, CHILE SO METEORITICS LA English DT Meeting Abstract C1 LOCKHEED ESC,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 2 TC 1 Z9 1 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 254 EP 255 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900124 ER PT J AU SOCKI, RA ROMANEK, CS GIBSON, EK ALLTON, JH AF SOCKI, RA ROMANEK, CS GIBSON, EK ALLTON, JH TI HYDROGEN AND OXYGEN ISOTOPE EXCHANGE IN HYDRATED CARBONATES FROM AN H-5 CHONDRITE - CLUES TO THE FORMATION OF WEATHERING PRODUCTS ON LEW85320 SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,LESC,HOUSTON,TX 77058. NR 7 TC 1 Z9 1 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 290 EP 290 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900203 ER PT J AU THOMAS, KL KELLER, LP BLANFORD, GE MCKAY, DS AF THOMAS, KL KELLER, LP BLANFORD, GE MCKAY, DS TI HIGH-CARBON ABUNDANCES IN IDPS - HYDRATED PARTICLES FROM COMETARY SOURCES SO METEORITICS LA English DT Meeting Abstract C1 LOCKHEED, HOUSTON, TX 77058 USA. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. UNIV HOUSTON CLEAR LAKE, HOUSTON, TX 77058 USA. NR 6 TC 8 Z9 8 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 296 EP 297 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900216 ER PT J AU TREIMAN, AH AF TREIMAN, AH TI FOUNDATION OF FORENSIC METEORITICS SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 2 TC 3 Z9 3 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 298 EP 299 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900221 ER PT J AU TREIMAN, AH DEHART, JM AF TREIMAN, AH DEHART, JM TI A NEW CV3 CHONDRITE FIND SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 5 TC 3 Z9 3 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 299 EP 299 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900222 ER PT J AU ZOLENSKY, M BARRETT, R AF ZOLENSKY, M BARRETT, R TI COMPOSITIONAL VARIATIONS OF OLIVINES AND PYROXENES IN CHONDRITIC INTERPLANETARY DUST PARTICLES SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LOCKHEED ESCO,HOUSTON,TX. NR 6 TC 2 Z9 2 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1992 VL 27 IS 3 BP 312 EP 313 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JE029 UT WOS:A1992JE02900248 ER PT J AU TONCICH, SS BHASIN, KB CHEN, TK CLASPY, PC AF TONCICH, SS BHASIN, KB CHEN, TK CLASPY, PC TI PERFORMANCE OF A WIDE-BAND GAAS LOW-NOISE AMPLIFIER AT CRYOGENIC TEMPERATURES SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE GAAS LOW-NOISE AMPLIFIER; CRYOGENIC TEMPERATURES; MICROWAVE MEASUREMENTS AB The gain, noise figure, and 1-dB compression point of a commercially available GaAs amplifier were measured at cryogenic temperatures. The gain and noise figure characteristics were improved by decreasing temperature, while the 1-dB compression point remained unchanged. Repeated temperature cycling had no adverse effect on amplifier performance. RP TONCICH, SS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD JUL PY 1992 VL 5 IS 8 BP 372 EP 374 DI 10.1002/mop.4650050809 PG 3 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA HU352 UT WOS:A1992HU35200008 ER PT J AU SHEN, MZ SCHAEFER, HF PARTRIDGE, H AF SHEN, MZ SCHAEFER, HF PARTRIDGE, H TI THE REMARKABLE ENNEAHYDRIDORHENATE DIANION - REH92- SO MOLECULAR PHYSICS LA English DT Article ID ABINITIO CALCULATIONS; ELECTRONIC-STRUCTURE AB All-electron, non-relativistic ab initio self-consistent field (SCF) quantum mechanical methods were applied to the unique enneahydridorhenate dianion (ReH92-, D3h). Three basis sets were constructed and used for rhenium: the (20s14p11d7f/17s11p8d2f) basis is loosely designated DZ; the (23s17p14d9f/18s14p10d3f) is similarly designated TZ; and TZ plus polarization plus diffuse is designated TZP+. The largest basis set, TZP+, has 24s20p15d10f primitive Gaussian functions contracted to 19s17p11d4f. Four basis sets were used for H: the (5s/3s) is designated TZ; (5s2p/3s2p) is designated TZ2P; (6s2p/4s2p) is designated QZ2P; and QZ2P plus one diffuse s function is designated QZ2P +. The well-known experimental D3h structure was investigated, with the three independent internal coordinates optimized using analytic gradient techniques. The larger basis sets were handled using the direct SCF approach. The largest basis set for which the geometry was optimized was TZP + for Re and QZ2P + for H (with 252 basis functions, where pure 5d and 7f sets of functions were used), and should approach closely the non-relativistic Hartree-Fock limit. Harmonic vibrational frequencies were obtained for two basis sets, the larger of which is TZ for Re and QZ2P for H (for a total of 221 basis functions). The molecular geometry seems to have approached the Hartree-Fock limit, and the six symmetry-equivalent prism Re-H bonds are predicted to be longer than the three cap Re-H bonds by 0.06 angstrom. The predicted equilibrium geometry and harmonic vibrational frequencies generally agree with available experimental data. The reason for the apparent agreement may be the accidental cancellation of relativistic effects and electron correlation effects. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SHEN, MZ (reprint author), UNIV GEORGIA,CTR COMPUTAT QUANTUM CHEM,ATHENS,GA 30602, USA. NR 32 TC 6 Z9 6 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0026-8976 J9 MOL PHYS JI Mol. Phys. PD JUL PY 1992 VL 76 IS 4 BP 995 EP 1007 DI 10.1080/00268979200101801 PG 13 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JF811 UT WOS:A1992JF81100015 ER PT J AU VAUGHAN, OH BLAKESLEE, R BOECK, WL VONNEGUT, B BROOK, M MCKUNE, J AF VAUGHAN, OH BLAKESLEE, R BOECK, WL VONNEGUT, B BROOK, M MCKUNE, J TI A CLOUD-TO-SPACE LIGHTNING AS RECORDED BY THE SPACE-SHUTTLE PAYLOAD-BAY TV CAMERAS SO MONTHLY WEATHER REVIEW LA English DT Article C1 NIAGARA UNIV,NEW YORK,NY. SUNY ALBANY,DEPT ATMOSPHER SCI,ALBANY,NY 12222. NEW MEXICO INST MIN & TECHNOL,DEPT PHYS,SOCORRO,NM 87801. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP VAUGHAN, OH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES43,HUNTSVILLE,AL 35812, USA. NR 3 TC 57 Z9 57 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUL PY 1992 VL 120 IS 7 BP 1459 EP 1461 DI 10.1175/1520-0493(1992)120<1459:ACTSLA>2.0.CO;2 PG 3 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JE026 UT WOS:A1992JE02600020 ER PT J AU BROWN, MR BELLAN, PM AF BROWN, MR BELLAN, PM TI EFFICIENCY AND SCALING OF CURRENT DRIVE AND REFUELING BY SPHEROMAK INJECTION INTO A TOKAMAK SO NUCLEAR FUSION LA English DT Article ID MAGNETIC HELICITY; MAGNETOHYDRODYNAMIC TURBULENCE; CYLINDRICAL GEOMETRY; TILTING INSTABILITY; COMPACT TOROIDS; PLASMA-GUN; SUSTAINMENT; RELAXATION AB The first measurements of current drive (refluxing) and refuelling by spheromak injection into a tokamak are discussed in detail. The current drive mechanism is attributed to the process of helicity injection, and refuelling is attributed to the rapid incorporation of the dense spheromak plasma into the tokamak. After an abrupt increase (up to 80%), the tokamak current decays by a factor of three because of plasma cooling caused by the merging of the relatively cold spheromak with thc tokamak. The tokamak density profile peaks sharply because of the injected spheromak plasma (n(e) increases by a factor of six) and then becomes hollow, suggestive of an interchange instability. Also discussed is the energy efficiency of spheromak injection current drive and the scaling of this process to larger machines. Refuelling by spheromak injection appears to be a viable scheme for larger machines. However, refluxing by spheromak injection is limited by geometrical and electrical efficiencies (both about 10%) as well as a high repetition rate requirement. RP BROWN, MR (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 31 TC 35 Z9 35 U1 1 U2 2 PU INT ATOMIC ENERGY AGENCY PI VIENNA PA WAGRAMERSTRASSE 5, PO BOX 100, A-1400 VIENNA, AUSTRIA SN 0029-5515 J9 NUCL FUSION JI Nucl. Fusion PD JUL PY 1992 VL 32 IS 7 BP 1125 EP 1137 DI 10.1088/0029-5515/32/7/I04 PG 13 WC Physics, Fluids & Plasmas SC Physics GA JF540 UT WOS:A1992JF54000004 ER PT J AU SCHIMMERLING, W AF SCHIMMERLING, W TI GALACTIC COSMIC-RADIATION - CONSTRAINTS ON SPACE EXPLORATION - EDITORIAL SO NUCLEAR TRACKS AND RADIATION MEASUREMENTS LA English DT Editorial Material RP SCHIMMERLING, W (reprint author), NASA,SPACE RADIAT HLTH PROGRAM,CODE SBM,NASA HEADQUARTERS,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0735-245X J9 NUCL TRACKS RAD MEAS PD JUL PY 1992 VL 20 IS 3 BP 395 EP 396 PG 2 WC Nuclear Science & Technology SC Nuclear Science & Technology GA JH942 UT WOS:A1992JH94200002 ER PT J AU BADHWAR, GD ONEILL, PM AF BADHWAR, GD ONEILL, PM TI AN IMPROVED MODEL OF GALACTIC COSMIC-RADIATION FOR SPACE EXPLORATION MISSIONS SO NUCLEAR TRACKS AND RADIATION MEASUREMENTS LA English DT Article ID MODULATION; SPECTRA; GRADIENTS; ELEMENTS; CHARGE; HELIUM; RAYS AB The need for an accurate model that describes the galactic cosmic radiation, GCR, environment is becoming increasingly important in light of planned space exploration missions. There is concern about the effets of heavy ions on crew health and electronic components. Recent studies have indicated that H, He, C, O, Ne, Mg, Si and Fe nuclei contribute about 80% of the radiation dose-equivalent under realistic shielding conditions. Small uncertainties in the absolute differential flux of these particles lead to large uncertainties in the amount of shielding mass needed for crew radiation protection. The absolute flux and the associated errors have received less attention than charge composition measurements. The Naval Research Laboratory (Adams, 1986) developed a comprehensive model, called the CREME model, that summarized the then-existing GCR data in terms of empirical fits. This model has been used for GCR intensities for shielding and single event upset studies. The main weakness of this model lies in its simple treatment of the solar modulation. In this paper we describe the results of a systematic study of existing data from 1965 to 1990 to derive a more accurate GCR environment model. We have fitted the hydrogen, helium, and iron spectra from 1965 to 1990, and have shown that a consistent set of local interstellar spectra and solar modulation parameters can be developed that applies to all species. A thorough analysis of uncertainties shows that the model spectra can be defined to an absolute accuracy of +/- 10%. A reference spectrum at solar minimum, which will be the limiting GCR spectrum for exploratory class missions, has been defined. RP BADHWAR, GD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 38 TC 67 Z9 69 U1 2 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0735-245X J9 NUCL TRACKS RAD MEAS PD JUL PY 1992 VL 20 IS 3 BP 403 EP 410 PG 8 WC Nuclear Science & Technology SC Nuclear Science & Technology GA JH942 UT WOS:A1992JH94200004 ER PT J AU BLAKE, JB BAKER, DN AF BLAKE, JB BAKER, DN TI LONG-TERM MEASUREMENTS OF THE INTEGRAL GALACTIC COSMIC-RAY FLUXES IN GEOSTATIONARY ORBIT SO NUCLEAR TRACKS AND RADIATION MEASUREMENTS LA English DT Article AB Measurements have been made serendipitously of the integral fluxes of galactic cosmic rays in geostationary orbit for over a decade. The GCR appear as background counts in an instrument designed to measure the fluxes and energy spectra of relativistic magnetospheric electrons. This database is described in this brief report. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BLAKE, JB (reprint author), AEROSPACE CORP,POB 92957,LOS ANGELES,CA 90009, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0735-245X J9 NUCL TRACKS RAD MEAS PD JUL PY 1992 VL 20 IS 3 BP 411 EP 413 PG 3 WC Nuclear Science & Technology SC Nuclear Science & Technology GA JH942 UT WOS:A1992JH94200005 ER PT J AU DERRICKSON, JH PARNELL, TA AUSTIN, RW SELIG, WJ GREGORY, JC AF DERRICKSON, JH PARNELL, TA AUSTIN, RW SELIG, WJ GREGORY, JC TI A MEASUREMENT OF THE ABSOLUTE ENERGY-SPECTRA OF GALACTIC COSMIC-RAYS DURING THE 1976-77 SOLAR MINIMUM SO NUCLEAR TRACKS AND RADIATION MEASUREMENTS LA English DT Article AB An instrument designed to measure elemental cosmic ray abundances from boron to nickel in the energy region 0.5-2.0 GeV nucl-1 was flown on a high altitude balloon from Sioux Falls, South Dakota, on 30 September through 1 October 1976 at an average atmospheric depth of approximately 5 g cm-2. Differential energy spectra of B, C, N, O, Ne, Mg, Si and Fe, extrapolated to the top of the atmosphere, were measured. The float altitude exposure of 17 h ended near Alpena, Michigan. The flight trajectory maintained a north easterly heading out of Sioux Falls traversing the upper mid-west region between 84-degrees and 97-degrees west longitude while remaining between 43.5-degrees and 45-degrees north latitude. The maximum vertical cut-off for this flight path was 1.77 GV or 0.35 GeV nucl-1 (Shea and Smart (1975), Report No. AFCRL-TR-75-0185, Air Force Cambridge Research Laboratories). C1 UNIV ALABAMA,DEPT CHEM,HUNTSVILLE,AL 35899. RP DERRICKSON, JH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 22 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0735-245X J9 NUCL TRACKS RAD MEAS PD JUL PY 1992 VL 20 IS 3 BP 415 EP 421 PG 7 WC Nuclear Science & Technology SC Nuclear Science & Technology GA JH942 UT WOS:A1992JH94200006 ER PT J AU SEO, ES ORMES, JF STREITMATTER, RE STOCHAJ, SJ JONES, WV STEPHENS, SA BOWEN, T AF SEO, ES ORMES, JF STREITMATTER, RE STOCHAJ, SJ JONES, WV STEPHENS, SA BOWEN, T TI MEASUREMENT OF THE COSMIC-RAY PROTON AND HELIUM FLUXES FROM 200 MEV NUCL-1 TO 100 GEV NUCL-1 DURING THE 1987 SOLAR MINIMUM SO NUCLEAR TRACKS AND RADIATION MEASUREMENTS LA English DT Article ID SPECTRA; ENERGY; SPECTROMETER; HELIOSPHERE; PERFORMANCE; MODULATION AB The galactic cosmic ray proton and helium spectra have been measured with a balloon-borne superconducting magnetic spectrometer over the energy range from 200 MeV nucl-1 to 100 GeV nucl-1 during the 1987 solar minimum between the 21st and 22nd solar cycle. The absolute fluxes were approximately equal to the highest fluxes observed at the previous solar minimum in 1977. Above 10 GV the observed spectra are represented by a power law in rigidity with spectral indices of 2.74 +/- 0.02 for protons and 2.68 +/- 0.03 for helium. The data are consistent with rigidity power law interstellar spectra modulated with the solar modulation parameter-phi = 500 MV. C1 NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771. LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803. UNIV ARIZONA,DEPT PHYS,TUCSON,AZ 85721. NEW MEXICO STATE UNIV,PARTICLE ASTROPHYS LAB,LAS CRUCES,NM 88003. OI Seo, Eun-Suk/0000-0001-8682-805X NR 30 TC 7 Z9 7 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0735-245X J9 NUCL TRACKS RAD MEAS PD JUL PY 1992 VL 20 IS 3 BP 431 EP 444 PG 14 WC Nuclear Science & Technology SC Nuclear Science & Technology GA JH942 UT WOS:A1992JH94200009 ER PT J AU BADHWAR, GD BRABY, LA CUCINOTTA, FA ATWELL, W AF BADHWAR, GD BRABY, LA CUCINOTTA, FA ATWELL, W TI DOSE-RATE, DOSE-EQUIVALENT RATE, AND QUALITY FACTOR IN SLS-1 SO NUCLEAR TRACKS AND RADIATION MEASUREMENTS LA English DT Article AB A tissue-equivalent proportional counter (TEPC) sensitive to the lineal energy range of 0.26-300 keV-mu-m-1 was flown on STS-40 (39-degrees x 278 km x 296 km) inside the Spacelab. This instrument was previously flown on STS-31 but was modified to provide a finer resolution at lower lineal energies to better map the South Atlantic Anomaly (SAA) protons. The instrument was turned on 6 June 1991, and operated for 7470 min (124.5 h). The flight duration was characterized by a very large number of X-ray solar flares and enhanced magnetic field fluctuations; however, no significant dose from the solar particles was measured at the location of this instrument. The flight data can be separated into trapped and galactic cosmic radiation parts. The dose rate, dose-equivalent rate and quality factor for trapped radiation were 4.21 +/- 0.03 mrad day-1, 7.72 +/- 0.05 mrem day-1, and 1.83 +/- 0.1, respectively. The dose rate, dose-equivalent rate, and quality factor for galactic cosmic radiation were 5.34 +/- 0.03 mrad day-1, 14.63 +/- 0.06 mrem day-1, and 2.74 +/- 0.1, respectively. The overall quality factor for the flight was 2.38. The dose from the GCR is higher than from SAA protons because of the high inclination and low altitude of this flight. The AP8MAX model of the trapped radiation gives a dose rate of 2.43 mrad day-1 and a quality factor of 1.77. The CREME solar maximum model of galactic cosmic radiation gives a dose mte of 2.54 mrad day-1 and a quality factor of 2.91. Thus the AP8MAX model underestimates the dose by a factor of 1.8 whereas the CREME model leads to an underestimation of the dose by a factor of 2. A comparison of the LET spectra using the AP8MAX model and galactic cosmic radiation transport codes shows only a qualitative agreement. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. ROCKWELL INT INC, HOUSTON, TX 77058 USA. PACIFIC NW LAB, RICHLAND, WA 99352 USA. RP BADHWAR, GD (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. NR 7 TC 6 Z9 6 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0735-245X J9 NUCL TRACKS RAD MEAS PD JUL PY 1992 VL 20 IS 3 BP 447 EP 451 PG 5 WC Nuclear Science & Technology SC Nuclear Science & Technology GA JH942 UT WOS:A1992JH94200010 ER PT J AU LARSSON, AG MASERJIAN, J AF LARSSON, AG MASERJIAN, J TI MOLECULAR-BEAM EPITAXY ENGINEERED III-V SEMICONDUCTOR STRUCTURES FOR LOW-POWER OPTICALLY ADDRESSED SPATIAL LIGHT MODULATORS SO OPTICAL ENGINEERING LA English DT Article DE OPTICAL INFORMATION PROCESSING; OPTICAL MODULATION; SPATIAL LIGHT MODULATORS; QUANTUM WELLS STRUCTURES; DELTA-DOPING; INTERFEROMETRIC STRUCTURES ID I-P-I; PEROT REFLECTION MODULATORS; QUANTUM-WELL STRUCTURES; DOPING SUPERLATTICES; MQW STRUCTURES; ABSORPTION; DESIGN AB Device approaches are investigated for optically addressed SLMs based on molecular beam epitaxy (MBE) engineered III-V materials and structures. Strong photo-optic effects can be achieved in periodically delta-doped multiple quantum well structures, but are still insufficient for high-contrast modulation with only single- or double-pass absorption through active layers of practical thickness. We use the asymmetric Fabry-Perot cavity approach that permits extinction of light due to interference of light reflected from the front and back surfaces of the cavity. Optically controlled modulation of the absorption in the active cavity layers unbalances the cavity and "turns on" the reflected output signal, thereby allowing large contrast ratios. This approach is realized with an all-MBE-grown structure consisting of GaAs/AlAs quarter-wave stack reflector grown over the GaAs substrate as the high reflectance mirror (almost-equal-to 0.98) and the GaAs surface as the low reflectance mirror (almost-equal-to 0.3). We use for our active cavity InGaAs/GaAs multiple quantum wells separated by periodically delta-doped GaAs barriers to achieve a sensitive photo-optic effect due to exciton quenching. High-contrast modulation (> 60:1) is achieved using a low-power (< 100 mW/cm2) InGaAs/GaAs quantum well laser for the control signal. RP LARSSON, AG (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 23 TC 17 Z9 17 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD JUL PY 1992 VL 31 IS 7 BP 1576 EP 1582 DI 10.1117/12.57683 PG 7 WC Optics SC Optics GA JD558 UT WOS:A1992JD55800029 ER PT J AU REGAN, JD CARRIER, WL GUCINSKI, H OLLA, BL YOSHIDA, H FUJIMURA, RK WICKLUND, RI AF REGAN, JD CARRIER, WL GUCINSKI, H OLLA, BL YOSHIDA, H FUJIMURA, RK WICKLUND, RI TI DNA AS A SOLAR DOSIMETER IN THE OCEAN SO PHOTOCHEMISTRY AND PHOTOBIOLOGY LA English DT Article ID ULTRAVIOLET-RADIATION; NATURAL-WATERS AB Stratospheric ozone depletion may result in increased solar UV-B radiation to the ocean's upper layers and may cause deleterious effects on marine organisms. The primary UV-B damage induced in biological systems is to DNA. While physical measurements of solar UV-B penetration into the sea have been made, the effective depth and magnitude of actual DNA damage have not been determined. In the experiments reported here, UV-B-induced photoproducts (cyclobutane pyrimidine dimers) have been quantified in DNA molecules exposed to solar UV at the surface and at various depths in clear, tropical marine waters off Lee Stocking Island (23-degrees 45-degrees N, 76-degrees 0.7' W), Exuma Cays, Bahamas. [C-14]thymidine-labeled DNA or unlabeled bacteriophage phi-X174 DNA was placed in specially designed quartz tubes at various depths for up to five days. Following exposure, DNA samples were removed to the laboratory where UV-B-induced pyrimidine dimers were quantified using a radiochromatographic assay, and bacteriophage DNA inactivation by solar UV-B was assayed by plaque formation in spheroplasts of Escherichia coli. Pyrimidine dimer induction was linear with time but the accumulation of dimers in DNA with time varied greatly with depth. Attenuation of dimer formation with depth of water was exponential. DNA at 3 m depth had only 17% of the pyrimidine dimers found at the surface. Bacteriophage phi-X174 DNA, while reduced 96% in plaque-forming ability by a one day exposure to solar UV at the surface of the water, showed no effect on plaque formation after a similar exposure at 3 m. The data collected at the water's surface showed a "surface-enhanced dose" in that DNA damages at the real surface were greater than at the imaginary surface, which was obtained by extrapolating the data at depth to the surface. These results show the sensitivity of both the biochemical (dimers) and biological (phage plaques) DNA dosimeters. DNA dosimeters offer a sensitive, convenient and relatively inexpensive monitoring system, having both biochemical and biological endpoints for monitoring the biologically effective UV-B flux in the marine environment. Unlike physical dosimeters. DNA dosimeters do not have to be adjusted for biological effectiveness since they are sensitive only to DNA-mediated biologically effective UV-B radiation. Results of pyrimidine dimer induction in DNA by solar UV accurately predicted UV doses to the phage DNA. C1 US EPA,MANTECH ENVIRONM TECHNOL INC,ENVIRONM RES LAB,CORVALLIS,OR 97333. ALASKA FISHERIES CTR,NATL MARINE FISHERIES SERV,HATFIELD MARINE SCI CTR,NEWPORT,OR 97365. CARIBBEAN MARINE RES CTR,EXUMA CAYS,BAHAMAS. OAK RIDGE NATL LAB,DIV BIOL,OAK RIDGE,TN 37831. OAK RIDGE NATL LAB,DIV HLTH & SAFETY RES,OAK RIDGE,TN 37831. RP REGAN, JD (reprint author), FLORIDA INST TECHNOL,DEPT BIOL SCI,MELBOURNE,FL 32901, USA. NR 28 TC 80 Z9 82 U1 0 U2 0 PU AMER SOC PHOTOBIOLOGY PI AUGUSTA PA BIOTECH PARK, 1021 15TH ST, SUITE 9, AUGUSTA, GA 30901-3158 SN 0031-8655 J9 PHOTOCHEM PHOTOBIOL JI Photochem. Photobiol. PD JUL PY 1992 VL 56 IS 1 BP 35 EP 42 DI 10.1111/j.1751-1097.1992.tb09599.x PG 8 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA JF185 UT WOS:A1992JF18500006 PM 1387234 ER PT J AU VOLZ, MP SU, CH LEHOCZKY, SL SZOFRAN, FR AF VOLZ, MP SU, CH LEHOCZKY, SL SZOFRAN, FR TI VIBRONIC SPECTRA OF CU2+ IN ZNTE SO PHYSICAL REVIEW B LA English DT Article ID II-VI-COMPOUNDS; INFRARED-ABSORPTION; TRANSITION-METALS; ZNS; CDTE AB Infrared-absorption spectra of substitutional Cu2+ ions in ZnTe have been measured at 4.6 K. Several distinct absorption peaks are observed between 800 and 2000 cm-1. Absorption peaks at 1002 and 1069 cm-1 are identified as zero-phonon lines arising from 2T2-->2E transitions. Between 1069 and 2000 cm-1 several sets of sharp absorption lines are seen to recur regularly at an interval of 2 10 cm-1, corresponding to the LO phonon energy. Within each set distinct vibronic sidebands that cannot be identified with critical-point energies of TA, LA, TO, or LO phonon modes are observed. A dynamic Jahn-Teller effect, involving coupling between a single-phonon mode and the electronic states of the 2E level, is proposed to account for the observed spectra. The spectra are adequately described by a Jahn-Teller interaction in the linear-coupling approximation and by including only coupling to epsilon-cluster modes. The observed first-order spin-orbit splitting in the 2T2 state is much reduced from crystal-field-theory predictions and a dynamic Jahn-Teller interaction in the ground 2T2 state is shown to account for this effect. RP NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, HUNTSVILLE, AL 35812 USA. NR 22 TC 5 Z9 5 U1 1 U2 1 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9950 EI 2469-9969 J9 PHYS REV B JI Phys. Rev. B PD JUL 1 PY 1992 VL 46 IS 1 BP 76 EP 82 DI 10.1103/PhysRevB.46.76 PG 7 WC Physics, Condensed Matter SC Physics GA JC556 UT WOS:A1992JC55600008 ER PT J AU YAKHOT, V ORSZAG, SA THANGAM, S GATSKI, TB SPEZIALE, CG AF YAKHOT, V ORSZAG, SA THANGAM, S GATSKI, TB SPEZIALE, CG TI DEVELOPMENT OF TURBULENCE MODELS FOR SHEAR FLOWS BY A DOUBLE EXPANSION TECHNIQUE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID RENORMALIZATION-GROUP; REYNOLDS AB Turbulence models are developed by supplementing the renormalization group (RNG) approach of Yakhot and Orszag [J. Sci. Comput. 1, 3 (1986)] with scale expansions for the Reynolds stress and production of dissipation terms. The additional expansion parameter (eta = SKBAR/epsilon(BAR)) is the ratio of the turbulent to mean strain time scale. While low-order expansions appear to provide an adequate description for the Reynolds stress, no finite truncation of the expansion for the production of dissipation term in powers of eta suffices-terms of all orders must be retained. Based on these ideas, a new two-equation model and Reynolds stress transport model are developed for turbulent shear flows. The models are tested for homogeneous shear flow and flow over a backward facing step. Comparisons between the model predictions and experimental data are excellent. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. STEVENS INST TECHNOL LIB,HOBOKEN,NJ 07030. RP YAKHOT, V (reprint author), PRINCETON UNIV,PRINCETON,NJ 08544, USA. NR 34 TC 808 Z9 904 U1 9 U2 43 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD JUL PY 1992 VL 4 IS 7 BP 1510 EP 1520 DI 10.1063/1.858424 PG 11 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA HZ842 UT WOS:A1992HZ84200017 ER PT J AU LANDIS, GA AF LANDIS, GA TI ADAPTIVE OPTICS - ADDITIONAL ADVANCES AND APPLICATIONS SO PHYSICS TODAY LA English DT Letter RP LANDIS, GA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD JUL PY 1992 VL 45 IS 7 BP 13 EP 13 PG 1 WC Physics, Multidisciplinary SC Physics GA JB862 UT WOS:A1992JB86200003 ER PT J AU KUMAR, D CLAIR, TLS AF KUMAR, D CLAIR, TLS TI NOVEL AMINO-ARYLOXYCYCLOTRIPHOSPHAZENE POLYMER PRECURSORS AND INTERMEDIATES - SOLVENT DEPENDENT SYNTHESIS AND CHARACTERIZATION SO POLYHEDRON LA English DT Article ID FIRE-RESISTANT; RESINS AB An efficient synthesis of tris(4-nitrophenoxy)tris(phenoxy)cyclotriphosphazene starting from hexachlorocyclotriphosphazene is described for varied reaction conditions. Two stereoisomers of tris(4-nitrophenoxy)tris(phenoxy)cyclotriphosphazenes (III and III*) have shown melting points of 111-112-degrees-C and 133-135-degrees-C, respectively. A process has been given to separate III and III* by chemical crystallization from a reaction product. The low-pressure hydrogenation of III and III* in solution in the presence of the catalyst platinum oxide has resulted in the reduction of nitro groups to the corresponding stereoisomers tris(4-aminophenoxy)tris(phenoxy)cyclotriphosphazenes IV and IV*, melting at 161-162-degrees-C and 107-108-degrees-C, respectively. All the products have been characterized by P-31 NMR, FT-IR, H-1 NMR, mass spectrometry and elemental analysis. Differential scanning calorimetry has been used to determine their melting behaviour. C1 NASA,LANGLEY RES CTR,POLYMER MAT BRANCH,HAMPTON,VA 23665. NR 18 TC 5 Z9 6 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0277-5387 J9 POLYHEDRON JI Polyhedron PD JUL PY 1992 VL 11 IS 13 BP 1671 EP 1678 DI 10.1016/S0277-5387(00)83723-7 PG 8 WC Chemistry, Inorganic & Nuclear; Crystallography SC Chemistry; Crystallography GA JF279 UT WOS:A1992JF27900017 ER PT J AU FAWCETT, SC DOW, TA AF FAWCETT, SC DOW, TA TI INFLUENCE OF WHEEL SPEED ON SURFACE FINISH AND CHIP GEOMETRY IN PRECISION CONTOUR GRINDING SO PRECISION ENGINEERING-JOURNAL OF THE AMERICAN SOCIETY FOR PRECISION ENGINEERING LA English DT Article DE GRINDING; DUCTILE REGIME GRINDING; OPTICS; SURFACE FINISH; CHIP GEOMETRY; SPEED EFFECT AB A geometric computer model of a precision grinding operation was developed to calculate the surface features generated during contour grinding with a radiused wheel. This simulation includes the influence of the wheel (rotational speed, diameter, and nose radius), the workpiece (radius at cutting point, rotational speed), and the feedrate of the grinding wheel over the part. The model indicates that small changes in the wheel speed relative to the workpiece can have a dramatic effect on the surface finish over a specific area. Analysis of ground surfaces reveals uniform surface profiles and easily distinguished features that could only be produced by a constant wheel speed. This occurs for an air-bearing, air-turbine grinding spindle that has limited torque and is driven under open-loop control. The effects of the relative speeds are analyzed and an energy-based "phase locking" mechanism is proposed that can provide feedback to the grinding spindle from the material removal operation. By monitoring the spindle speeds during the grinding process and evaluating the resulting surface features, the phase effect has been experimentally verified. RP FAWCETT, SC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,OPT SYST BRANCH,HUNTSVILLE,AL 35812, USA. NR 0 TC 4 Z9 4 U1 0 U2 3 PU BUTTERWORTH-HEINEMANN PI WOBURN PA 225 WILDWOOD AVE #UNITB PO BOX 4500, WOBURN, MA 01801-2084 SN 0141-6359 J9 PRECIS ENG JI Precis. Eng.-J. Am. Soc. Precis. Eng. PD JUL PY 1992 VL 14 IS 3 BP 160 EP 167 DI 10.1016/0141-6359(92)90005-H PG 8 WC Engineering, Multidisciplinary; Engineering, Manufacturing; Nanoscience & Nanotechnology; Instruments & Instrumentation SC Engineering; Science & Technology - Other Topics; Instruments & Instrumentation GA JF418 UT WOS:A1992JF41800004 ER PT J AU SCHIMMERLING, W AF SCHIMMERLING, W TI RADIOBIOLOGICAL PROBLEMS IN SPACE - AN OVERVIEW SO RADIATION AND ENVIRONMENTAL BIOPHYSICS LA English DT Article; Proceedings Paper CT 4TH WORKSHOP ON HEAVY CHARGED PARTICLES IN BIOLOGY AND MEDICINE CY SEP 23-25, 1991 CL DARMSTADT, GERMANY SP GESELL SCHWERIONENFORSCH ID COLLISIONS; NUCLEI AB An overview is presented on radiation problems in space, with emphasis on aspects of major interest for manned space exploration. A classification of the radiation hazards is presented and strategies for their evaluation are discussed. Space radiation problems are compared with characteristic aspects of radiation research in other disciplines, in order to provide further insight into those aspects that are unique to space. C1 JET PROP LAB,PASADENA,CA 91109. NR 26 TC 27 Z9 28 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0301-634X J9 RADIAT ENVIRON BIOPH JI Radiat. Environ. Biophys. PD JUL PY 1992 VL 31 IS 3 BP 197 EP 203 DI 10.1007/BF01214827 PG 7 WC Biology; Biophysics; Environmental Sciences; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Environmental Sciences & Ecology; Radiology, Nuclear Medicine & Medical Imaging GA JB070 UT WOS:A1992JB07000003 PM 1502328 ER PT J AU RODRIGUEZ, E KIM, YJ DURDEN, SL AF RODRIGUEZ, E KIM, YJ DURDEN, SL TI A NUMERICAL ASSESSMENT OF ROUGH-SURFACE SCATTERING THEORIES - HORIZONTAL POLARIZATION SO RADIO SCIENCE LA English DT Article ID PHASE-PERTURBATION TECHNIQUE; COMPOSITE RANDOM SURFACES; KIRCHHOFF APPROXIMATION; ELECTROMAGNETIC SCATTERING; ACOUSTIC SCATTERING; VALIDITY; SPECTRUM; WAVES AB We present a numerical evaluation of the regime of validity for various rough surface scattering theories against numerical results obtained by using the method of moments. The theories are the small perturbation method, the Kirchhoff approximation, the momentum transfer expansion, the two-scale expansion, and a new theory, which we call the unified perturbation method. Both the field and phase perturbation expansions for these theories are examined. It is outlined how all these theories can be derived in a unified manner starting with the extinction theorem. We consider the contribution of each theory up to second order in the perturbation expansion for the surface current. The rough surfaces considered are oceanlike surfaces, which exhibit height power law spectra. RP RODRIGUEZ, E (reprint author), JET PROP LAB,4800 OAK GROVE DR,MS 300-235,PASADENA,CA 91109, USA. NR 32 TC 21 Z9 22 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD JUL-AUG PY 1992 VL 27 IS 4 BP 497 EP 513 DI 10.1029/92RS00502 PG 17 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA JH054 UT WOS:A1992JH05400006 ER PT J AU KIM, YJ RODRIGUEZ, E DURDEN, SL AF KIM, YJ RODRIGUEZ, E DURDEN, SL TI A NUMERICAL ASSESSMENT OF ROUGH-SURFACE SCATTERING THEORIES - VERTICAL POLARIZATION SO RADIO SCIENCE LA English DT Article ID PHASE-PERTURBATION TECHNIQUE; ELECTROMAGNETIC SCATTERING; KIRCHHOFF APPROXIMATION; VALIDITY; WAVES; SPECTRUM AB In a previous paper, we presented a numerical evaluation of the regime of validity for various rough surface scattering theories. The evaluation was done for horizontal polarization by comparing these theories against numerical results obtained by the method of moments. In this paper we address the same issues for vertical polarization. The theories considered here are the small perturbation method, the Kirchhoff approximation, the momentum transfer expansion, the two-scale expansion, and the unified perturbation method (UPM). All these theories can be derived in a unified manner starting with the extinction theorem. The rough surfaces of interest are oceanlike surfaces. which exhibit height power law spectra. Considering both horizontal and vertical polarizations, the UPM provides best results among all theories considered. RP KIM, YJ (reprint author), JET PROP LAB,300-319,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 28 TC 14 Z9 14 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD JUL-AUG PY 1992 VL 27 IS 4 BP 515 EP 527 DI 10.1029/91RS02637 PG 13 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA JH054 UT WOS:A1992JH05400007 ER PT J AU CHEUNG, E LUMELSKY, V AF CHEUNG, E LUMELSKY, V TI REAL-TIME PATH PLANNING PROCEDURE FOR A WHOLE-SENSITIVE ROBOT ARM MANIPULATOR SO ROBOTICA LA English DT Article DE PATH-PLANNING; SENSITIVE ARM; REAL-TIME PLANNING; ROBOT ARM AB We consider the problem of sensor-based motion planning for a three-dimensional robot arm manipulator operating among unknown obstacles. When every point of the robot body is subject to potential collision. The corresponding planning system must include these four basic components: sensor hardware; real-time signal/sensory data processing hardware/software; a local step planning subsystem that works at the basic sample rate of the arm; and finally, a subsystem for global planning. The arm sensor system developed at Yale University presents a proximity sensitive skin that covers the whole body of the arm and consists of an array of discrete active infrared sensors that detect obstacles by processing reflected light. The sensor data then undergoes low level processing via a step planning procedure, which converts sensor information into local normals at the contact points in the configuration space of the robot. This paper presents preliminary results on the fourth component, a real-time algorithm that realizes the upper, global level of planning. Based on the current collection of local normals, the algorithm generates preferable directions of motion around obstacles, so as to guarantee reaching the target position if it is reachable. Experimental results from testing the developed system are also discussed. RP CHEUNG, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,JACKSON & TULL,CODE 714-1,BLDG T-11-B,GREENBELT,MD 20771, USA. NR 0 TC 5 Z9 5 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0263-5747 J9 ROBOTICA JI Robotica PD JUL-AUG PY 1992 VL 10 BP 339 EP 349 PN 4 PG 11 WC Robotics SC Robotics GA JA885 UT WOS:A1992JA88500006 ER PT J AU MALARIK, DC VANNUCCI, RD AF MALARIK, DC VANNUCCI, RD TI HIGH-MOLECULAR-WEIGHT 1ST GENERATION PMR POLYIMIDES FOR 343-DEGREES-C APPLICATIONS SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article AB The effect of molecular weight on 343-degrees-C thermo-oxidative stability (TOS), mechanical properties, and processability, of the first generation PMR polyimides was investigated. Graphite fiber reinforced PMR-15, PMR-30, PMR-50, and PMR-75 composites (corresponding to formulated molecular weights of 1500, and 7500, respectively) were fabricated utilizing a simulated autoclave process. The data reveals that, while alternate autoclave cures schedules are required for the high molecular weight resins, low void laminates can be fabricated which have significantly improved TOS over PMR-15, with only a small sacrifice in mechanical properties. RP MALARIK, DC (reprint author), NASA,LEWIS RES CTR,DIV MAT,POLYMERS BRANCH,CLEVELAND,OH 44135, USA. NR 5 TC 2 Z9 3 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0036-0821 J9 SAMPE QUART PD JUL PY 1992 VL 23 IS 4 BP 3 EP 8 PG 6 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA JE350 UT WOS:A1992JE35000002 ER PT J AU STOAKLEY, DM STCLAIR, AK AF STOAKLEY, DM STCLAIR, AK TI LOW COEFFICIENT OF THERMAL-EXPANSION POLYIMIDES CONTAINING METAL-ION ADDITIVES SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article AB Polyimides have become widely used as high performance polymers as a result of their excellent thermal stability and toughness. However, lowering their coefficient of thermal expansion (CTE) would increase their usefulness for aerospace and electronic applications where dimensional stability is a requirement. The CTE's of conventional polyimides range from 30 to 60 ppm/degrees-C. Approaches that have been reported to lower their CTE's include linearizing the polymer molecular structure and orienting the polyimide film. This current study involves the incorporation of metal ion-containing additives into polyimides and has resulted in significantly lowered CTE's. Various metal ion additives have been added to both polyamic acid resins and soluble polyimide solutions in the concentration range of 4-23 weight percent. The incorporation of these metal ions has resulted in reductions in the CTE's of the control polyimides of 12% to over 100% depending on the choice of additive and its concentration. RP STOAKLEY, DM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 13 TC 4 Z9 4 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0036-0821 J9 SAMPE QUART PD JUL PY 1992 VL 23 IS 4 BP 9 EP 13 PG 5 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA JE350 UT WOS:A1992JE35000003 ER PT J AU GERBER, MK PATER, RH AF GERBER, MK PATER, RH TI FILM PROPERTIES OF HIGH-PERFORMANCE SEMIINTERPENETRATING POLYIMIDE NETWORKS SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article AB Phase separation and phase instability remain major obstacles preventing widespread acceptance of the semi-interpenetrating polyimide network (semi-IPN) as a tough composite matrix for aerospace structural applications. One approach to overcoming this problem is to provide a semi-IPN in which the constituent materials have the same cheMical structure and polymer chain length. This concept was tested in this investigation. A nadic endcapped LARC-TPI polyamic acid having a formulated molecular weight of 20,000 was prepared and then combined with commercial LARC-TPI polyamic acid. Three semi-IPN films were prepared and tested along with the pure comPonents. The physical and mechanical properties of the polyimide films were determined. All films exhibited one-phase morphology and had essentially identical chemical structure and physical properties. RP GERBER, MK (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0036-0821 J9 SAMPE QUART PD JUL PY 1992 VL 23 IS 4 BP 53 EP 57 PG 5 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA JE350 UT WOS:A1992JE35000009 ER PT J AU BRYAN, K VOGELIUS, M AF BRYAN, K VOGELIUS, M TI A UNIQUENESS RESULT CONCERNING THE IDENTIFICATION OF A COLLECTION OF CRACKS FROM FINITELY MANY ELECTROSTATIC BOUNDARY MEASUREMENTS SO SIAM JOURNAL ON MATHEMATICAL ANALYSIS LA English DT Article DE CRACKS; NONDESTRUCTIVE TESTING; ELECTRICAL IMPEDANCE IMAGING AB The problem of identification of a collection of finitely many cracks inside a planar domain is considered. The data used for the identification consist of measurements of the electrostatic boundary potentials induced by prescribed current fluxes. It is shown that a collection of n or fewer cracks is uniquely identified by boundary measurements corresponding to n + 1 specific current fluxes, consisting entirely of electrode pairs. C1 RUTGERS STATE UNIV,DEPT MATH,NEW BRUNSWICK,NJ 08903. RP BRYAN, K (reprint author), NASA,ICASE,HAMPTON,VA 23665, USA. NR 2 TC 38 Z9 38 U1 1 U2 4 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 0036-1410 J9 SIAM J MATH ANAL JI SIAM J. Math. Anal. PD JUL PY 1992 VL 23 IS 4 BP 950 EP 958 DI 10.1137/0523051 PG 9 WC Mathematics, Applied SC Mathematics GA HZ286 UT WOS:A1992HZ28600009 ER PT J AU NACHTIGAL, NM REDDY, SC TREFETHEN, LN AF NACHTIGAL, NM REDDY, SC TREFETHEN, LN TI HOW FAST ARE NONSYMMETRIC MATRIX ITERATIONS SO SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS LA English DT Article DE ITERATIVE METHOD; CONJUGATE GRADIENT ITERATION; NORMAL EQUATIONS; KRYLOV SPACE; PSEUDOSPECTRUM; CGN; GMRES; BCG; CGS ID LINEAR-EQUATIONS; SYSTEMS; ALGORITHM AB Three leading iterative methods for the solution of nonsymmetric systems of linear equations are CGN (the conjugate gradient iteration applied to the normal equations), GMRES (residual minimization in a Krylov space), and CGS (a biorthogonalization algorithm adapted from the biconjugate gradient iteration). Do these methods differ fundamentally in capabilities? If so, which is best under which circumstances? The existing literature, in relying mainly on empirical studies, has failed to confront these questions systematically. In this paper it is shown that the convergence of CGN is governed by singular values and that of GMRES and CGS by eigenvalues or pseudo-eigenvalues. The three methods are found to be fundamentally different, and to substantiate this conclusion, examples of matrices are presented for which each iteration outperforms the others by a factor of size O(square-root N) or O(N) where N is the matrix dimension. Finally, it is shown that the performance of iterative methods for a particular matrix cannot be predicted from the properties of its symmetric part. C1 NYU,COURANT INST MATH SCI,NEW YORK,NY 10012. CORNELL UNIV,DEPT COMP SCI,ITHACA,NY 14853. RP NACHTIGAL, NM (reprint author), NASA,AMES RES CTR,ADV COMP SCI RES INST,MAIL STOP T041-5,MOFFETT FIELD,CA 94035, USA. NR 31 TC 183 Z9 187 U1 0 U2 7 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 0895-4798 J9 SIAM J MATRIX ANAL A JI SIAM J. Matrix Anal. Appl. PD JUL PY 1992 VL 13 IS 3 BP 778 EP 795 DI 10.1137/0613049 PG 18 WC Mathematics, Applied SC Mathematics GA HZ289 UT WOS:A1992HZ28900008 ER EF