FN Thomson Reuters Web of Science™ VR 1.0 PT J AU LEATHERWOOD, JD CLEVENSON, SA POWELL, CA DANIELS, EF AF LEATHERWOOD, JD CLEVENSON, SA POWELL, CA DANIELS, EF TI ACOUSTIC TESTING OF HIGH-TEMPERATURE PANELS SO JOURNAL OF AIRCRAFT LA English DT Article AB This paper summarizes recent thermoacoustic test activities at NASA Langley Research Center. The Langley Thermal Acoustic Fatigue Apparatus facility is described and results of two experiments to measure dynamic strain response of advanced structural panels at ambient and elevated temperatures are presented. The first study investigated techniques for measuring the dynamic strain of superalloy honeycomb thermal protection system panels subjected to combined thermal and acoustic loads. Results illustrating the linear response of these panels as a function of sound pressure level and temperature are presented. The second study was a joint NASA/General Dynamics test of two flat and two blade-stiffened carbon-carbon panels. These panels were tested to failure at an acoustic excitation level of 160 dB. Failure times ranged from several minutes to about 3 h. The flat panels failed due to development of edge-cracks, and the blade-stiffened panels due to delamination. Results showed that the carbon-carbon panels tested at elevated temperatures had significantly longer fatigue life. Strain data from both types of panels were obtained, although difficulties were encountered in returning reliable strain measurements on the carbon-carbon panels. RP LEATHERWOOD, JD (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST,STRUCT ACOUST BRANCH,HAMPTON,VA 23665, USA. NR 0 TC 3 Z9 4 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 NOV-DEC PY 1992 VL 29 IS 6 BP 1130 EP 1136 DI 10.2514/3.46295 PG 7 WC Engineering, Aerospace SC Engineering GA KB465 UT WOS:A1992KB46500024 ER PT J AU LEBLANC, AD SCHNEIDER, VS EVANS, HJ PIENTOK, C ROWE, R SPECTOR, E AF LEBLANC, AD SCHNEIDER, VS EVANS, HJ PIENTOK, C ROWE, R SPECTOR, E TI REGIONAL CHANGES IN MUSCLE MASS FOLLOWING 17 WEEKS OF BED REST SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE MUSCLE ATROPHY; MAGNETIC RESONANCE IMAGING; DUAL-PHOTON ABSORPTIOMETRY; NITROGEN BALANCE ID DUAL-PHOTON ABSORPTIOMETRY; SOFT-TISSUE; TOTAL-BODY; PROTEIN BREAKDOWN; 3-METHYLHISTIDINE; PRECISION AB This work reports on the muscle loss and recovery after 17 wk of continuous bed rest and 8 wk of reambulation in eight normal male volunteers. Muscle changes were assessed by urinary levels of 3-methylhistidine (3-MeH), nitrogen balance, dual-photon absorptiometry (DPA), magnetic resonance imaging (MRI), and isokinetic muscle performance. The total body lean tissue loss during bed rest calculated from nitrogen balance was 3.9 +/- 2.1 (SD) kg (P < 0.05). Although the total loss is minimal, DPA scans showed that nearly all of the lean tissue loss occurred in the lower limbs. Similarly, MRI muscle volume measurements showed greater percent loss in the limbs relative to the back muscles. MRI, DPA, and nitrogen balance suggest that muscle atrophy continued throughout bed rest with rapid recovery after reambulation. Isokinetic muscle strength decreased significantly (P < 0.05) in the thigh and calf with no loss in the arms and with rapid recovery during reambulation. We conclude that there is great variability in the degree and location of muscle loss in bed rest and that the lower limb muscles are primarily affected. C1 NASA,LYNDON B JOHNSON SPACE CTR,NATL AERONAUT & SPACE ADM,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX 77058. BAYLOR COLL MED,DEPT MED,HOUSTON,TX 77030. FU NCRR NIH HHS [RR-02558, RR-00350] NR 18 TC 208 Z9 211 U1 1 U2 9 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 NOV PY 1992 VL 73 IS 5 BP 2172 EP 2178 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JZ596 UT WOS:A1992JZ59600067 PM 1474100 ER PT J AU BACK, LH CRAWFORD, DW AF BACK, LH CRAWFORD, DW TI WALL SHEAR-STRESS ESTIMATES IN CORONARY-ARTERY CONSTRICTIONS SO JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID FLOW CHARACTERISTICS; BLOOD-FLOW; STENOSES; MODELS AB Wall shear stress estimates from laminar boundary layer theory were found to agree fairly well with the magnitude of shear stress levels along coronary artery constrictions obtained from solutions of the Navier Stokes equations for both steady and pulsatile flow. The relatively simple method can be used for in vivo estimates of wall shear stress in constrictions by using a vessel shape function determined from a coronary angiogram, along with a knowledge of the flow rate. C1 UNIV SO CALIF,DEPT MED,DIV CARDIOL,LOS ANGELES,CA 90089. RP BACK, LH (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 24 TC 21 Z9 21 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0148-0731 J9 J BIOMECH ENG-T ASME JI J. Biomech. Eng.-Trans. ASME PD NOV PY 1992 VL 114 IS 4 BP 515 EP 520 DI 10.1115/1.2894104 PG 6 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA KB055 UT WOS:A1992KB05500014 PM 1487905 ER PT J AU SNOWHARTER, C WHALEN, R MYBURGH, K ARNAUD, S MARCUS, R AF SNOWHARTER, C WHALEN, R MYBURGH, K ARNAUD, S MARCUS, R TI BONE-MINERAL DENSITY, MUSCLE STRENGTH, AND RECREATIONAL EXERCISE IN MEN SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Article ID BODY-COMPOSITION; WEIGHT; WOMEN; SPINE; MASS AB Muscle strength has been shown to predict bone mineral density (BMD) in women. We examined this relationship in 50 healthy men who ranged in age from 28 to 51 years (average 38.3 years). BMD of the lumbar spine, proximal femur, whole body, and tibia were measured by dual-energy x-ray absorptiometry (Hologic QDR 1000W). Dynamic strength using one repetition maximum was assessed for the biceps, quadriceps, and back extensors and for the hip abductors, adductors, and flexors. Isometric grip strength was measured by dynamometry. Daily walking mileage was assessed by 9 week stepmeter records and kinematic analysis of video filming. Subjects were designated as exercisers and nonexercisers. Exercisers participated in recreational exercise at least two times each week. The results demonstrated that BMD at all sites correlated with back and biceps strength (p < 0.01 to p = 0.0001). Body weight correlated with tibia and whole-body BMD (p < 0.001); age negatively correlated with Ward's triangle BMD (p < 0.01). In stepwise multiple regressions, back strength was the only independent predictor of spine and femoral neck density (R2 = 0.27). Further, back strength was the most robust predictor of BMD at the trochanter, Ward's triangle, whole body, and tibia, although biceps strength, age, body weight, and leg strength contributed significantly to BMD at these skeletal sites, accounting for 35-52% of the variance in BMD. Exercisers and nonexercisers were similar for walking (3.97 versus 3.94 miles/day), age (37.8 versus 38.5 years), and weight (80.0 versus 77.7 kg). However, BMD and muscle strength were significantly greater in exercisers than in nonexercisers. In conclusion, in young to middle-aged men, (1) muscle strength makes important contributions to bone mineral density; (2) strength of back extensors more powerfully predicts BMD than age, body weight, or strength of other muscle groups; and (3) recreational exercise is a better predictor of BMD than habitual daily walking. C1 VET ADM MED CTR,CTR GERIATR RES EDUC & CLIN AGING STUDY UNIT,PALO ALTO,CA 94304. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. STANFORD UNIV,DEPT MED,PALO ALTO,CA 94304. OI Myburgh, Kathryn/0000-0003-4501-2120 NR 18 TC 82 Z9 82 U1 0 U2 2 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 NOV PY 1992 VL 7 IS 11 BP 1291 EP 1296 PG 6 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA JY182 UT WOS:A1992JY18200007 PM 1466254 ER PT J AU MYBURGH, KH ZHOU, LJ STEELE, CR ARNAUD, S MARCUS, R AF MYBURGH, KH ZHOU, LJ STEELE, CR ARNAUD, S MARCUS, R TI INVIVO ASSESSMENT OF FOREARM BONE MASS AND ULNAR BENDING STIFFNESS IN HEALTHY-MEN SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Article ID POSTMENOPAUSAL WOMEN; AGE; FRACTURES; IDENTIFICATION; STRENGTH; RADIUS AB The cross-sectional bending stiffness El of the ulna was measured in vivo by mechanical resistance tissue analysis (MRTA) in 90 men aged 19-89 years. MRTA measures the impedance response of low-frequency vibrations to determine EI, which is a reflection of elastic modulus E and moment of inertia I for the whole ulna. EI was compared to conventional estimates of bone mineral content (BMC), bone width (BW), and BMC/BW, which were all measured by single-photon absorptiometry. Results obtained from the nondominant ulna indicate that BW increases (r = 0.27, p = 0.01) and ulnar BMC/BW decreases (r = -0.31, p less-than-or-equal-to 0.005) with age. Neither BMC nor EI declined with age. The single best predictor of EI was BW (r2 = 0.47, p = 0.0001), and further small but significant contributions were made by BMC (r2 = 0.53, p = 0.0001) and grip strength (r2 = 0.55, p = 0.0001). These results suggest that the resistance of older men to forearm fracture is related to age-associated changes in the moment of inertia achieved by redistributing bone mineral farther from the bending axis. We conclude that the in vivo assessment of bone geometry offers important insights to the comprehensive evaluation of bone strength. C1 VET ADM MED CTR,CTR GERIATR RES EDUC & CLIN,MUSCULOSKELETAL RES LAB,PALO ALTO,CA 94304. STANFORD UNIV,DEPT MED,STANFORD,CA 94305. STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. OI Myburgh, Kathryn/0000-0003-4501-2120 NR 26 TC 26 Z9 27 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 NOV PY 1992 VL 7 IS 11 BP 1345 EP 1350 PG 6 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA JY182 UT WOS:A1992JY18200014 PM 1466258 ER PT J AU MARTIN, JML LEE, TJ SCUSERIA, GE TAYLOR, PR AF MARTIN, JML LEE, TJ SCUSERIA, GE TAYLOR, PR TI ABINITIO MULTIREFERENCE STUDY OF THE BN MOLECULE SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID QUADRATIC CONFIGURATION-INTERACTION; GAUSSIAN BASIS FUNCTIONS; COUPLED-CLUSTER METHOD; ATOMIC BASIS SETS; FULL CCSDT MODEL; FIRST-ROW ATOMS; MRD-CI METHOD; ELECTRONIC-STRUCTURE; TRIPLE EXCITATIONS; ENERGY EXTRAPOLATION AB The lowest 1SIGMA+ and 3PI states of the BN molecule have been studied using multireference configuration interaction (MRCI) and averaged coupled-pair functional (ACPF) methods and large atomic natural orbital (ANO) basis sets, as well as several coupled cluster methods. Our best calculations strongly support a 3PI ground state, but the a 1SIGMA+ state lies only 381 +/- 100 cm-1 higher. The a 1SIGMA+ state wave function exhibits strong multireference character and, consequently, the predictions of the perturbationally-based single-reference CCSD(T) coupled cluster method are not as reliable in this case as the multireference results. The best theoretical predictions for the spectroscopic constants of BN are in good agreement with experiment for the X3PI state, but strongly suggest a misassignment of the fundamental vibrational frequency for the a 1SIGMA+ state. C1 RICE UNIV, DEPT CHEM, HOUSTON, TX 77251 USA. RICE UNIV, RICE QUANTUM INST, HOUSTON, TX 77251 USA. ELORET INST, PALO ALTO, CA 94303 USA. LIMBURGS UNIV CENTRUM, DEPT SBG, B-3590 DIEPENBEEK, BELGIUM. UNIV INSTELLING ANTWERP, DEPT CHEM, INST MAT SCI, B-2610 WILRIJK, BELGIUM. RP MARTIN, JML (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Scuseria, Gustavo/F-6508-2011; Lee, Timothy/K-2838-2012; Martin, Jan/A-7457-2008 OI Martin, Jan/0000-0002-0005-5074 NR 56 TC 72 Z9 73 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD NOV 1 PY 1992 VL 97 IS 9 BP 6549 EP 6556 DI 10.1063/1.463684 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JX295 UT WOS:A1992JX29500061 ER PT J AU LEE, TJ ROHLFING, CM RICE, JE AF LEE, TJ ROHLFING, CM RICE, JE TI AN EXTENSIVE ABINITIO STUDY OF THE STRUCTURES, VIBRATIONAL-SPECTRA, QUADRATIC FORCE-FIELDS, AND RELATIVE ENERGETICS OF 3 ISOMERS OF CL2O2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID GAUSSIAN-BASIS SETS; CHLORINE OXIDE DIMER; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; HYDROGEN-PEROXIDE; INFRARED-SPECTRUM; OZONE DEPLETION; TRIPLE EXCITATIONS; TRANSITION-STATE AB The three lowest-lying isomers Of Cl2O2 have been investigated using state-of-the-art ab initio quantum-mechanical methods. Electron correlation methods that have been used include second-order Moller-Plesset perturbation theory, singles and doubles coupled-cluster (CCSD) theory, and the CCSD(T) method, which incorporates a perturbational estimate of the effects of connected triple excitations. Accurate relative energies have been obtained using the CCSD(T) method in conjunction with large atomic natural orbital basis sets that include up to g-type functions. Our best estimate is that the ClClO2 and ClOClO isomers lie 0.9 +/- 2.0 and 10.1 +/- 4.0 kcal/mol higher in energy (0 K), respectively, than the more stable ClOOCl peroxide form. In order to obtain accurate equilibrium geometries it is necessary to include f-type functions in the one-particle basis set. The vibrational spectra (including IR intensities) of all three isomers are computed and compared with experimental data for ClOOCl and ClClO2. The theoretical and experimental vibrational frequencies agree very well except for the symmetric combination of Cl-0 stretches in ClOOCl, where it is concluded that the experimental band is most likely due to the antisymmetric Cl-0 stretch. The heat of formation of ClOOCl is computed using an isodesmic reaction involving Cl2O, H2O, and HOOH, and determined to be 34.2 kcal/mol (0 K). The largest uncertainty in this value is due to potential errors in the experimental heat of formation Of Cl2O. Using the experimental heat of formation of CIO, the dissociation energy of ClOOCl relative to 2 CIO is computed to be 14.9 kcal/mol at 298 K. The equilibrium structures and vibrational spectra Of Cl2O, H2O, and HOOH from our highest-level calculations are found to be in excellent agreement with the available experimental data. C1 SANDIA NATL LABS, DIV THEORET, LIVERMORE, CA 94551 USA. IBM CORP, ALMADEN RES CTR, RES DIV, SAN JOSE, CA 95120 USA. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Rice, Julia/K-4928-2012; Lee, Timothy/K-2838-2012 OI Rice, Julia/0000-0001-5059-5127; NR 66 TC 97 Z9 97 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD NOV 1 PY 1992 VL 97 IS 9 BP 6593 EP 6605 DI 10.1063/1.463663 PG 13 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JX295 UT WOS:A1992JX29500066 ER PT J AU LELE, SK AF LELE, SK TI COMPACT FINITE-DIFFERENCE SCHEMES WITH SPECTRAL-LIKE RESOLUTION SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID NUMERICAL-SIMULATION; BOUNDARY-CONDITIONS; ELEMENT METHOD; CHANNEL FLOW; TURBULENCE; LAYER C1 NASA,AMES RES CTR,CTR TURBULENCE RES,MOFFETT FIELD,CA 94035. STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. NR 51 TC 2514 Z9 2670 U1 12 U2 98 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 NOV PY 1992 VL 103 IS 1 BP 16 EP 42 DI 10.1016/0021-9991(92)90324-R PG 27 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JV669 UT WOS:A1992JV66900002 ER PT J AU TSAI, CT YAO, MW CHAIT, A AF TSAI, CT YAO, MW CHAIT, A TI PREDICTION OF DISLOCATION GENERATION DURING BRIDGMAN GROWTH OF GAAS CRYSTALS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID PLASTIC-DEFORMATION; SINGLE-CRYSTALS; CZOCHRALSKI GROWTH; SILICON-CRYSTALS; PULLED GAAS; DYNAMICS; BEHAVIOR; MODEL; VELOCITIES; RIBBON AB Dislocation densities are generated in GaAs single crystals due to the excessive thermal stresses induced by temperature variations during growth. A viscoplastic material model for GaAs, which takes into account the movement and multiplication of dislocations in the plastic deformation, is developed according to Haasen's theory. The dislocation density is expressed as an internal state variable in this dynamic viscoplastic model. The deformation process is a nonlinear function of stress, strain rate, dislocation density and temperature. The dislocation density in the GaAs crystal during vertical Bridgman growth is calculated using a nonlinear finite element model. The dislocation multiplication in GaAs crystals for several temperature fields obtained from thermal modeling of both the GTE GaAs experimental data and artificially designed data are investigated. C1 OHIO AEROSP INST,BROOK PK,OH 44142. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP TSAI, CT (reprint author), FLORIDA ATLANTIC UNIV,DEPT MECH ENGN,BOCA RATON,FL 33431, USA. RI Tsai, C.T./A-4605-2008 NR 31 TC 38 Z9 41 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 NOV PY 1992 VL 125 IS 1-2 BP 69 EP 80 DI 10.1016/0022-0248(92)90322-A PG 12 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA KA518 UT WOS:A1992KA51800010 ER PT J AU MCCANN, RS FOLK, CL JOHNSTON, JC AF MCCANN, RS FOLK, CL JOHNSTON, JC TI THE ROLE OF SPATIAL ATTENTION IN VISUAL WORD-PROCESSING SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article ID UNATTENDED PRINTED WORDS; SELECTIVE-ATTENTION; LEXICAL ACCESS; LETTER STRINGS; ILLUSORY CONJUNCTIONS; REPETITION BLINDNESS; AUTOMATIC PROCESSES; VERIFICATION MODEL; DIVIDED ATTENTION; LETTER PERCEPTION AB Subjects made lexical decisions on a target letter string presented above or below fixation. In Experiments 1 and 2, target location was cued 100 ms in advance of target onset. ResPonses were faster on validly than on invalidly cued trials. In Experiment 3, the target was sometimes accompanied by irrelevant stimuli on the other side of fixation; in such cases, responses were slowed (a spatial filtering effect). Both cuing and filtering effects on response time were additive with effects of word frequency and lexical status (words vs. nonwords). These findings are difficult to reconcile with claims that spatial attention is less involved in processing familiar words than in unfamiliar words and nonwords. The results can be reconciled with a late-selection locus of spatial attention only with difficulty, but are easily explained by early-selection models. C1 STERLING SOFTWARE,PALO ALTO,CA. VILLANOVA UNIV,VILLANOVA,PA 19085. RP MCCANN, RS (reprint author), NASA,AMES RES CTR,MAIL STOP 262-3,MOFFETT FIELD,CA 94035, USA. NR 111 TC 77 Z9 79 U1 6 U2 10 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD NOV PY 1992 VL 18 IS 4 BP 1015 EP 1029 DI 10.1037/0096-1523.18.4.1015 PG 15 WC Psychology; Psychology, Experimental SC Psychology GA JU804 UT WOS:A1992JU80400009 PM 1431741 ER PT J AU FOLK, CL REMINGTON, RW JOHNSTON, JC AF FOLK, CL REMINGTON, RW JOHNSTON, JC TI INVOLUNTARY COVERT ORIENTING IS CONTINGENT ON ATTENTIONAL CONTROL SETTINGS SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article ID ABRUPT VISUAL ONSETS; SELECTIVE ATTENTION; SEARCH; MODEL; DISCRIMINATION; SIMILARITY; VOLUNTARY; PARALLEL; FEATURES; MOVEMENT AB Four experiments tested a new hypothesis that involuntary attention shifts are contingent on the relationship between the properties of the eliciting event and the properties required for task performance. In a variant of the spatial cuing paradigm, the relation between cue property and the property useful in locating the target was systematically manipulated. In Experiment 1, invalid abrupt-onset precues produced costs for targets characterized by an abrupt onset but not for targets characterized by a discontinuity in color. In Experiment 2, invalid color precues produced greater costs for color targets than for abrupt-onset targets. Experiment 3 provided converging evidence for this pattern. Experiment 4 investigated the boundary conditions and time course for attention shifts elicited by color discontinuities. The results of these experiments suggest that attention capture is contingent on attentional control settings induced by task demands. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP FOLK, CL (reprint author), VILLANOVA UNIV,DEPT PSYCHOL,VILLANOVA,PA 19085, USA. FU NIMH NIH HHS [1 RO3 MH 45008] NR 47 TC 1361 Z9 1384 U1 12 U2 110 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD NOV PY 1992 VL 18 IS 4 BP 1030 EP 1044 DI 10.1037//0096-1523.18.4.1030 PG 15 WC Psychology; Psychology, Experimental SC Psychology GA JU804 UT WOS:A1992JU80400010 PM 1431742 ER PT J AU FOSTER, MR JACQMIN, D AF FOSTER, MR JACQMIN, D TI NONPARALLEL EFFECTS IN THE INSTABILITY OF LONG VORTEX SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TRAILING LINE VORTEX; INVISCID STABILITY; NEUTRAL POINTS; DISTURBANCES; WAVENUMBER; MODES; FLOW AB As shown in Foster & Smith (1989), at large flow force M, Long's self-similar vortex is in the form of a swirling ring-jet, whose axial velocity profile is of sech2 form. At azimuthal wavenumber n of comparable order to the axial wavenumber, linear helical modes of instability are essentially those of the Bickley jet varicose and sinuous modes. However, at small axial wavenumbers, the three-dimensionality of the vortex is important, and the instabilities depend heavily on the effects of the swirl. We explore here the effects of finite Reynolds number Re on these long-wave inertial modes. It is shown that, because the radial velocity scales with Re-1 M, the non-parallelism of the flow is more important than the viscous terms in determining the finite-Re behaviour. The three-layer structure of the parallel-flow instability modes remains, but with a critical layer considerably modified by radial velocity. In investigating the critical range Re = O(M3), we find the following: for n > 1, the non-parallelism stabilizes the unstable inertial modes, leading to determination of neutral curves; for n < - 1, the non-parallel effects always destabilize the vortex to these helical modes. Determination of the unstable modes and neutral curves for the n > 1 case requires a computational scheme that accounts for the presence of viscosity. It turns out that the n > 1 (n < - 1) modes are prograde (retrograde) with respect to the rotation of the main vortex. C1 OHIO STATE UNIV,DEPT AERONAUT & ASTRONAUT ENGN,COLUMBUS,OH 43210. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 19 TC 14 Z9 14 U1 1 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 NOV PY 1992 VL 244 BP 289 EP 306 DI 10.1017/S0022112092003070 PG 18 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JZ760 UT WOS:A1992JZ76000014 ER PT J AU COLEMAN, GN FERZIGER, JH SPALART, PR AF COLEMAN, GN FERZIGER, JH SPALART, PR TI DIRECT SIMULATION OF THE STABLY STRATIFIED TURBULENT EKMAN LAYER SO JOURNAL OF FLUID MECHANICS LA English DT Article ID ATMOSPHERIC BOUNDARY-LAYER; FLUIDS; MODEL; FLOWS; FLUX AB The three-dimensional time-dependent turbulent flow in the stably stratified Ekman layer over a smooth surface is computed numerically by directly solving the Navier-Stokes equations, using the Boussinesq approximation to account for buoyancy effects. All relevant scales of motion are included in the simulation so that no turbulence model is needed. The Ekman layer is an idealization of the Earth's boundary layer and provides information concerning atmospheric turbulence models. We find that, when non-dimensionalized according to Nieuwstadt's local scaling scheme, some of the simulation data agree very well with atmospheric measurements. The results also suggest that Brost & Wyngaard's 'constant Froude number' and Hunt's 'shearing length' stable layer models for the dissipation rate of turbulent kinetic energy are both valid, when Reynolds number effects are accounted for. Simple gradient closures for the temperature variance and heat flux demonstrate the same variation with Richardson number as in Mason & Derbyshire's large-eddy simulation (LES) study, implying both that the models are relatively insensitive to Reynolds number and that local scaling should work well when applied to the stable atmospheric layer. In general we find good agreement between the direct numerical simulation (DNS) results reported here and Mason & Derbyshire's LES results. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. RP COLEMAN, GN (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 57 TC 55 Z9 55 U1 0 U2 4 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 NOV PY 1992 VL 244 BP 677 EP 712 DI 10.1017/S0022112092003264 PG 36 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JZ760 UT WOS:A1992JZ76000033 ER PT J AU DELCOURT, DC MOORE, TE SAUVAUD, JA CHAPPELL, CR AF DELCOURT, DC MOORE, TE SAUVAUD, JA CHAPPELL, CR TI NONADIABATIC TRANSPORT FEATURES IN THE OUTER CUSP REGION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CHARGED-PARTICLE MOTION; MAGNETIC-FIELD; BOUNDARY-LAYER; PLASMA SHEET; POLAR CUSP; MAGNETOSPHERE; MAGNETOPAUSE; MODEL; RECONNECTION; DIFFUSION AB The dayside to nightside circulation of plasma along the magnetopause inside the magnetosphere is examined by means of three-dimensional single-particle codes. It is demonstrated that particles incident upon the outer cusp region experience transient non-adiabatic motions, owing to a localized minimum in the field magnitude. Hem, possibly large magnetic moment changes yield injection into the loss cone of fractions of the incoming population or, alternatively, enhanced bouncing motions at high altitudes. It is shown that particles gaining access to the magnetotail over the polar cap are progressively extracted from the weak field region by the large-scale convection electric field. In this latter case, the trajectory simulations suggest an implicit "entry boundary" into the nightside magnetosphere, which corresponds to the sunward edge of field lines featuring monotonic decrease of the field magnitude along their length. C1 UNIV TOULOUSE 3,CTR ETUD SPATIALE RAYONNEMENTS,F-31062 TOULOUSE,FRANCE. CTR RECH PHYS ENVIRONN,F-94107 ST MAUR FOSSES,FRANCE. RP DELCOURT, DC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,CODE ES53,HUNTSVILLE,AL 35812, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 31 TC 23 Z9 23 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 NOV 1 PY 1992 VL 97 IS A11 BP 16833 EP 16842 DI 10.1029/92JA00834 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX753 UT WOS:A1992JX75300008 ER PT J AU LU, G REIFF, PH MOORE, TE HEELIS, RA AF LU, G REIFF, PH MOORE, TE HEELIS, RA TI UPFLOWING IONOSPHERIC IONS IN THE AURORAL REGION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SUPRATHERMAL O+ IONS; LATITUDE F-REGION; HIGH-ALTITUDE; POLAR-CAP; TRANSVERSE ACCELERATION; DISTRIBUTIONS; TEMPERATURES; MECHANISM; PARALLEL; ORIGIN AB Observations of upflowing ionospheric ions are obtained nearly simultaneously by DE 1 and DE 2 over the nightside auroral regions. At low altitudes, the mean value of the net upward ion number flux is of the order of 10(9) CM-2 s-1. The ionosphere is predominantly O+, and the flux of ions with energy greater than 5 eV is a very small fraction (less than 1%) of the total ion flux. At high altitudes, the upflowing ions are accelerated by a parallel electric field and heated (with characteristic energies of hundreds of electron volts). Comparing upflowing fluxes at high and low altitudes yields an estimated height of the bottom of the auroral acceleration region of 1400-1700 km for the region of peak potential drop. This low-altitude acceleration could either be from a parallel electric field or from perpendicular acceleration. The fluxes at the edges of the arc are mostly H+ thus implying a higher-altitude base of the acceleration region at the edges where the potential drop is lower. C1 UNIV TEXAS,CTR SPACE PHYS,RICHARDSON,TX 75083. RICE UNIV,DEPT SPACE PHYS & ASTRON,HOUSTON,TX 77251. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE PHYS LAB,HUNTSVILLE,AL 35812. RP LU, G (reprint author), NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,POB 3000,BOULDER,CO 80307, USA. RI Lu, Gang/A-6669-2011; Moore, Thomas/D-4675-2012; Reiff, Patricia/D-2564-2014 OI Moore, Thomas/0000-0002-3150-1137; Reiff, Patricia/0000-0002-8043-5682 NR 42 TC 35 Z9 35 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1992 VL 97 IS A11 BP 16855 EP 16863 DI 10.1029/92JA01435 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX753 UT WOS:A1992JX75300010 ER PT J AU VAGO, JL KINTNER, PM CHESNEY, SW ARNOLDY, RL LYNCH, KA MOORE, TE POLLOCK, CJ AF VAGO, JL KINTNER, PM CHESNEY, SW ARNOLDY, RL LYNCH, KA MOORE, TE POLLOCK, CJ TI TRANSVERSE ION-ACCELERATION BY LOCALIZED LOWER HYBRID WAVES IN THE TOPSIDE AURORAL IONOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PHASE-VELOCITY MEASUREMENTS; PLASMA-WAVES; ELECTROSTATIC NOISE; SUPRAURORAL REGION; SOLITARY WAVES; DOUBLE-LAYERS; VLF HISS; BEAM; ENERGIZATION; GENERATION AB Up to now, observations had been unable to show conclusively a one-to-one correspondence between perpendicular ion acceleration and a particular type of plasma wave within the O+ source region below 2000 km. In this paper we demonstrate that intense (100-300 mV/m) lower hybrid waves are responsible for transversely accelerating H+ and O+ ions to characteristic energies of up to 6 eV. This wave-particle interaction takes place in thin filamentary density cavities oriented along geomagnetic field lines. The measurements we discuss were conducted in the nightside auroral zone at altitudes between 500 km and 1100 km. Our results are consistent with theories of lower hybrid wave condensation and collapse. C1 CORNELL UNIV,SCH ELECT ENGN,ITHACA,NY 14853. UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 53 TC 129 Z9 129 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 NOV 1 PY 1992 VL 97 IS A11 BP 16935 EP 16957 DI 10.1029/92JA01526 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX753 UT WOS:A1992JX75300017 ER PT J AU TORR, MR TORR, DG RICHARDS, PG AF TORR, MR TORR, DG RICHARDS, PG TI THE N-2+ 1ST NEGATIVE SYSTEM IN THE DAYGLOW FROM SPACELAB-1 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID N2; MODEL; PHOTOCHEMISTRY; THERMOSPHERE; MIDLATITUDE; IONOSPHERE; CHEMISTRY; AFTERGLOW; IONS; O2 AB During the Spacelab 1 shuttle mission, the first spectral images of the N2+ first negative system in the dayglow were made with the Imaging Spectrometric Observatory, an array of imaging spectrometers that covered a wavelength range extending from the extreme ultraviolet to the near infrared. These data have been the subject of a comprehensive study involving additional ground-based observations, modeling of the causative mechanisms, and assessments of the predicted N2+ first negative system airglow on a semiglobal basis. Two surprising findings from these spectral images are that the bands of the N2+ first negative system exhibit very unusual vibrational distributions and that the intensities are significantly higher than anticipated. The spectra show unexpected populations up to v" = 4, a result that was not anticipated on the basis of prior theories. It is found that an apparent rotational temperature of approximately 3000 K is needed to explain the data, while the closest apparent vibrational temperature is approximately 6000 to 8000 K. Conventional thermospheric theory is not able to account for these vibrational distributions which appear to be present throughout the 10-day shuttle mission and in quite different vehicle orientations. In this paper we show examples of these spectra and then concentrate on comparing the measured absolute intensities of the 0-0 band at 3914 angstrom with the results from our inter-hemispheric thermospheric airglow model. After appropriate corrections are included for radiation backscattered from the atmosphere and the ground, the intensities are found to be larger than current theory predicts for midday conditions by factors greater than 3. At large solar zenith angles, these intensity data am consistent with the Atmosphere Explorer results. The question arises as Lo whether the enhanced midday intensities are due to unexplained processes in the natural dayglow or whether sources of N2+ exist in the shuttle environment which can lead to large intensity and vibrational population enhancements. Like the enhanced vibrational populations, the enhanced intensities are present over the course of the 10-day mission and do not appear to be associated with any particular vehicle attitude or viewing geometry. The intensity variation with solar zenith angle and viewing elevation appears to support the existence of a significant induced N2+ component near the shuttle, which fluoresces when the shuttle is sunlit. C1 UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899. RP TORR, MR (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 44 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1992 VL 97 IS A11 BP 17075 EP 17095 DI 10.1029/92JA00986 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX753 UT WOS:A1992JX75300027 ER PT J AU ROBERTS, DA GOLDSTEIN, ML MATTHAEUS, WH GHOSH, S AF ROBERTS, DA GOLDSTEIN, ML MATTHAEUS, WH GHOSH, S TI VELOCITY SHEAR GENERATION OF SOLAR-WIND TURBULENCE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID KELVIN-HELMHOLTZ INSTABILITY; INTERPLANETARY ALFVENIC FLUCTUATIONS; INHOMOGENEOUS MHD TURBULENCE; INTER-PLANETARY SPACE; MAGNETOHYDRODYNAMIC TURBULENCE; MAGNETIC-FIELD; INCOMPRESSIBLE MAGNETOHYDRODYNAMICS; RADIAL EVOLUTION; STREAM STRUCTURE; SPECTRA AB We use a two-dimensional, incompressible MHD spectral code to establish that shear-driven turbulence is a possible means for producing many observed properties of the evolution of the magnetic and velocity fluctuations in the solar wind and, in particular, the evolution of the cross helicity ("Alfvenicity") at small scales. We find that large-scale shear can nonlinearly produce a cascade to smaller scale fluctuations even when the linear Kelvin-Helmholtz mode is stable and that a roughly power law inertial range is established by this process. While the fluctuations thus produced are not Alfvenic, they are nearly equipartitioned between magnetic and kinetic energy. We report simulations with Alfvenic fluctuations at high wave numbers, both with and without shear layers and find that it is the low cross helicity at low wave numbers that is critical to the cross helicity evolution, rather than the geometry of the flow or the dominance of kinetic energy at large scales. The fluctuations, produced by shear effects are shown to evolve similarly but more slowly in the presence of a larger mean field and to be anisotropic with a preferred direction of spectral transfer perpendicular to the mean field. The evolution found is similar to that seen in some other simulations of MHD turbulence, and thus seems in many respects to be a instance of a more generic turbulent evolution rather than due to specific conditions in the solar wind. C1 UNIV DELAWARE, BARTOL RES INST, NEWARK, DE 19716 USA. RP ROBERTS, DA (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ORIENTAL & AFRICAN STUDIES LAB, GREENBELT, MD 20771 USA. RI Roberts, Dana/D-4625-2012; Goldstein, Melvyn/B-1724-2008 NR 75 TC 133 Z9 133 U1 1 U2 2 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 NOV 1 PY 1992 VL 97 IS A11 BP 17115 EP 17130 DI 10.1029/92JA01144 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX753 UT WOS:A1992JX75300029 ER PT J AU SAKURAI, T SPANGLER, SR ARMSTRONG, JW AF SAKURAI, T SPANGLER, SR ARMSTRONG, JW TI VERY LONG BASE-LINE INTERFEROMETER MEASUREMENTS OF PLASMA TURBULENCE IN THE SOLAR-WIND SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY SCINTILLATION; SPECTRUM; SUN; MICROTURBULENCE; PROPAGATION; EVOLUTION; STREAMS AB Turbulence in the solar wind plasma was studied using angular broadening measurements of 10 extragalactic compact radio sources (quasars) with a very long baseline interferometer (VLBI) at 4.99 GHz. Unlike other angular broadening studies, the measured broadening size was corrected for intrinsic source structures which were obtained from a separate VLBI observation. The solar elongations of the sources ranged from 18 R(S) to 243 R(S), and five sources with elongations less-than-or-equal-to 61 R(S) showed varying degrees of broadening. The measured angular sizes are considerably less than predicted by the well-known empirical relationship of Erickson [1964], as well as two other models for strength of scattering as a function of solar elongation. However, the data are in good agreement with a model for the spatial power spectrum of the turbulence proposed by Coles and Harmon [1989]. This model consists of a Kolmogorov spectrum at large scales, but with an enhancement of power near the wavenumber corresponding to the ion inertial length. Two of our sources, 1148-001 and 1253-053 (3C279), show substantial differences in the amount of scattering, even though they are at similar solar elongations (29 versus 35 R(S)). Data to which we have access indicate that the state of the corona along the lines of sight to these sources may have been quite different. Angular broadening measurements with VLBI interferometers currently under development (primarily the very long baseline array) will allow a global view of plasma turbulence out of the ecliptic plane and thus be complementary to the point in situ measurements with Ulysses. C1 JET PROP LAB,PASADENA,CA 91109. RP SAKURAI, T (reprint author), UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242, USA. NR 37 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1992 VL 97 IS A11 BP 17141 EP 17151 DI 10.1029/92JA01551 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX753 UT WOS:A1992JX75300031 ER PT J AU KAWANO, H YAMAMOTO, T KOKUBUN, S LEPPING, RP AF KAWANO, H YAMAMOTO, T KOKUBUN, S LEPPING, RP TI ROTATIONAL POLARITIES OF SUDDEN IMPULSES IN THE MAGNETOTAIL LOBE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Note AB A sudden impulse (SI) is a sudden change in the magnetic field strength which is caused by a change in the solar wind pressure and is observed throughout the magnetosphere. In this report we have examined the rotations of the magnetic field vectors at times of SIs in the magnetotail lobe, by using IMP 6, 7, and 8 magnetometer data. The following properties have been found: (1) At the time of SI the arrowhead of the magnetic vector tends to rotate in one plane. (2) The plane of rotation tends to include the unperturbed magnetic field vector. (3) The plane of rotation tends to be aligned with the radial direction from the magnetotail axis. (4) The magnetic vectors have a particular rotational polarity: when the plane of rotation is viewed so that the Sun is to the right of the viewed plane and the magnetotail axis is to the bottom, the arrowhead of the vector tends to rotate counterclockwise in this plane. These magnetic vector properties are consistent with those expected when part of an increase in solar wind lateral pressure squeezes the magnetotail axisymmetrically while moving tailward. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20723. RP KAWANO, H (reprint author), UNIV TOKYO,DEPT EARTH & PLANETARY PHYS,BUNKYO KU,TOKYO 113,JAPAN. NR 12 TC 20 Z9 22 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 NOV 1 PY 1992 VL 97 IS A11 BP 17177 EP 17182 DI 10.1029/92JA01250 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX753 UT WOS:A1992JX75300036 ER PT J AU DUNN, HJ AF DUNN, HJ TI EXPERIMENTAL RESULTS OF ACTIVE CONTROL ON A LARGE STRUCTURE TO SUPPRESS VIBRATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB The need to suppress vibration in large space structures is a continuing problem during design. Active control of structural vibration is one method that can be used to achieve lightweight structures with desirable damping characteristics. In this paper three design methods, linear quadratic Gaussian with loop transfer recovery, H(infinity), and mu synthesis, are used to obtain compensators for suppressing the vibrations of a 10-bay vertical truss structure, a component typical of what may be used to build a large space structure. For the design process the plant dynamic characteristics of the structure were determined experimentally using an identification method. The resulting compensators were implemented on a digital computer and tested for their ability to suppress the first bending mode response of the 10-bay vertical truss. For these experiments, the first bending mode is excited and the control system is used to damp the vibration. Time histories of the measured motion are presented, and modal damping obtained during the experiments is compared with analytical predictions. The advantages and disadvantages of using the various design methods are discussed. RP DUNN, HJ (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,AEROSERVOELASTIE BRANCH,HAMPTON,VA 23681, USA. NR 10 TC 3 Z9 3 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1992 VL 15 IS 6 BP 1334 EP 1341 DI 10.2514/3.11394 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JX062 UT WOS:A1992JX06200004 ER PT J AU KUMAR, RR COOPER, PA LIM, TW AF KUMAR, RR COOPER, PA LIM, TW TI SENSITIVITY OF SPACE STATION ALPHA-JOINT ROBUST CONTROLLER TO STRUCTURAL MODAL PARAMETER VARIATIONS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper describes the photovoltaic array sun tracking control system of Space Station Freedom. A synthesis procedure for determining optimized values of the design variables of the control system is developed by use of a constrained optimization technique. The synthesis is performed to provide a given level of stability margin, achieve the most responsive tracking performance, and meet other design requirements. Performance of the baseline design, which is synthesized using predicted structural characteristics, is discussed, and the sensitivity of the stability margin is examined for variations of the frequencies, mode shapes, and damping ratios of dominant structural modes. The design provides enough robustness to tolerate a sizeable error in the predicted modal parameters. The paper concludes with an investigation on the sensitivity of performance indicators as the modal parameters of the dominant modes vary, which would be useful in improving the control system performance if accurate modal data are provided through an on-orbit modal identification experiment. C1 NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP KUMAR, RR (reprint author), ANALYT MECH ASSOCIATES INC,HAMPTON,VA 23666, USA. NR 7 TC 2 Z9 2 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 NOV-DEC PY 1992 VL 15 IS 6 BP 1427 EP 1433 DI 10.2514/3.11406 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JX062 UT WOS:A1992JX06200016 ER PT J AU JAIN, A RODRIGUEZ, G AF JAIN, A RODRIGUEZ, G TI RECURSIVE FLEXIBLE MULTIBODY SYSTEM DYNAMICS USING SPATIAL OPERATORS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID FORMULATION AB This paper uses spatial operators to develop new spatially recursive dynamics algorithms for flexible multibody systems. The operator description of the dynamics is identical to that for rigid multibody systems. Assumed-mode models are used for the deformation of each individual body. The algorithms are based on two spatial operator factorizations of the system mass matrix. The first (Newton-Euler) factorization of the mass matrix leads to recursive algorithms for the inverse dynamics, mass matrix evaluation, and composite-body forward dynamics for the system. The second (innovations) factorization of the mass matrix, leads to an operator expression for the mass matrix inverse and to a recursive articulated-body forward dynamics algorithm. The primary focus is on serial chains, but extensions to general topologies are also described. A comparison of computational costs shows that the articulated-body, forward dynamics algorithm is much more efficient than the composite-body algorithm for most flexible multibody systems. RP JAIN, A (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 17 TC 42 Z9 53 U1 0 U2 8 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 NOV-DEC PY 1992 VL 15 IS 6 BP 1453 EP 1466 DI 10.2514/3.11409 PG 14 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JX062 UT WOS:A1992JX06200019 ER PT J AU BOLTZ, FW AF BOLTZ, FW TI ORBITAL MOTION UNDER CONTINUOUS TANGENTIAL THRUST SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note RP BOLTZ, FW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 6 TC 22 Z9 24 U1 0 U2 4 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 NOV-DEC PY 1992 VL 15 IS 6 BP 1503 EP 1507 DI 10.2514/3.56583 PG 5 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JX062 UT WOS:A1992JX06200026 ER PT J AU KWACK, EY SHAKKOTTAI, P LUCHIK, TS AARON, KM FABRIS, G BACK, LH AF KWACK, EY SHAKKOTTAI, P LUCHIK, TS AARON, KM FABRIS, G BACK, LH TI HOT-WIRE FILM BEHAVIOR IN LOW-TEMPERATURE GASES SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Article DE CRYOGENICS; FORCED CONVECTION; INSTRUMENTATION AB Commercially available hot wires/films were used to measure the velocities of evaporated hydrogen or helium gas during cryogenic mixing experiments. Hot wires were found to be too delicate to use in this harsh environment. Hot films were rugged enough to use at cryogenic temperatures even though they failed after a number of thermal cycles. Since the hot films have small aspect ratios, 13.4 and 20, they are quite sensitive to the thermal loading, T(w)/T(g), even with a correction for the conduction end loss. In general, although the increase of the Nusselt number with Reynolds number at low temperatures was similar to that at room temperature, there was also a pronounced variation with T(w)/T(g) over the large range of 1.2 to 12 investigated. RP KWACK, EY (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 17 TC 3 Z9 3 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-1481 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD NOV PY 1992 VL 114 IS 4 BP 859 EP 865 DI 10.1115/1.2911893 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA KA761 UT WOS:A1992KA76100009 ER PT J AU GOKOGLU, SA KUCZMARSKI, M VEITCH, LC AF GOKOGLU, SA KUCZMARSKI, M VEITCH, LC TI PREDICTION OF CHEMICAL VAPOR-DEPOSITION RATES ON MONOFILAMENTS AND ITS IMPLICATIONS FOR FIBER PROPERTIES SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID SILICON; KINETICS; REACTOR; SILANE; MODEL; CVD AB Deposition rates are predicted in a cylindrical upflow reactor designed for chemical vapor deposition (CVD) on monofilaments. Deposition of silicon from silane in a hydrogen carrier gas is chosen as a relevant example. The effects of gas and surface chemistry are studied in a two-dimensional axisymmetric flow field for this chemically well-studied system. Model predictions are compared to experimental CVD rate measurements. The differences in some physical and chemical phenomena between such small diameter (approximately 150 mum) fiber substrates and other typical CVD substrates are highlighted. The influence of the Soret mass transport mechanism is determined to be extraordinarily significant. The difficulties associated with the accurate measurement and control of the fiber temperature are discussed. Model prediction sensitivities are investigated with respect to fiber temperatures, fiber radii, Soret transport, and chemical kinetic parameters. The implications of the predicted instantaneous rates are discussed relative to the desired fiber properties for both batch and continuous processes. RP GOKOGLU, SA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 19 TC 0 Z9 0 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 NOV PY 1992 VL 7 IS 11 BP 3023 EP 3031 DI 10.1557/JMR.1992.3023 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA JX922 UT WOS:A1992JX92200016 ER PT J AU CHOI, SR SALEM, JA AF CHOI, SR SALEM, JA TI INDENTATION FLAW FORMATION AND STRENGTH RESPONSE OF SILICON-NITRIDE CERAMICS AT LOW INDENTATION LOADS SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article ID FIBERS; GLASS C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. RP CHOI, SR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 11 TC 3 Z9 3 U1 0 U2 0 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0261-8028 J9 J MATER SCI LETT JI J. Mater. Sci. Lett. PD NOV 1 PY 1992 VL 11 IS 21 BP 1398 EP 1400 DI 10.1007/BF00729639 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA JW120 UT WOS:A1992JW12000002 ER PT J AU HEYART, M PERRIN, A FLAUD, JM CAMYPEYRET, C RINSLAND, CP SMITH, MAH DEVI, VM AF HEYART, M PERRIN, A FLAUD, JM CAMYPEYRET, C RINSLAND, CP SMITH, MAH DEVI, VM TI THE NU-1 AND NU-3 BANDS OF O-16O-17O-16 LINE POSITIONS AND INTENSITIES SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID O-16O-18O-16; O-16O-16O-18 C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. UNIV PARIS 06,CNRS,F-75252 PARIS 05,FRANCE. RP HEYART, M (reprint author), UNIV PARIS 06,PHYS MOLEC & APPLICAT,TOUR 13,BTE 76,4 PL JUSSIEU,F-75252 PARIS 05,FRANCE. NR 10 TC 19 Z9 20 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD NOV PY 1992 VL 156 IS 1 BP 210 EP 216 DI 10.1016/0022-2852(92)90104-V PG 7 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA JU536 UT WOS:A1992JU53600018 ER PT J AU FUKUNAGA, T ROY, RR SHELLOCK, FG HODGSON, JA DAY, MK LEE, PL KWONGFU, H EDGERTON, VR AF FUKUNAGA, T ROY, RR SHELLOCK, FG HODGSON, JA DAY, MK LEE, PL KWONGFU, H EDGERTON, VR TI PHYSIOLOGICAL CROSS-SECTIONAL AREA OF HUMAN LEG MUSCLES BASED ON MAGNETIC-RESONANCE-IMAGING SO JOURNAL OF ORTHOPAEDIC RESEARCH LA English DT Article DE MAGNETIC RESONANCE IMAGING; MUSCLE VOLUME; MUSCLE ARCHITECTURE; PHYSIOLOGICAL CROSS-SECTIONAL AREA; HUMAN ID HUMAN LOWER-LIMB; SKELETAL-MUSCLE; CAT SOLEUS; ARCHITECTURE; STRENGTH; GASTROCNEMIUS; HINDLIMB AB Magnetic resonance imaging techniques were used to determine the physiological cross-sectional areas (PCSAs) of the major muscles or muscle groups of the lower leg. For 12 healthy subjects, the boundaries of each muscle or muscle group were digitized from images taken at 1-cm intervals along the length of the leg. Muscle volumes were calculated from the summation of each anatomical CSA (ACSA) and the distance between each section. Muscle length was determined as the distance between the most proximal and distal images in which the muscle was visible. The PCSA of each muscle was calculated as muscle volume times the cosine of the angle of fiber pinnation divided by fiber length, where published fiber length:muscle length ratios were used to estimate fiber lengths. The mean volumes of the major plantarflexors were 489, 245, and 140 cm3 for the soleus and medial (MG) and lateral (LG) heads of the gastrocnemius. The mean PCSA of the soleus was 230 cm2 , about three and eight times larger than the MG (68 cm2) and LG (28 cm2), respectively. These PCSA values were eight (soleus), four (MG), and three (LG) times larger than their respective maximum ACSA. The major dorsiflexor, the tibialis anterior (TA), had a muscle volume of 143 cm2, a PCSA of 19 cm2, and an ACSA of 9 cm2. With the exception of the soleus, the mean fiber length of all subjects was closely related to muscle volume across muscles. The soleus fibers were unusually short relative to the muscle volume, thus potentiating its force potential. Using the relationship between PCSA and fiber length to represent the maximum force-velocity potential of a muscle and assuming a similar moment arm, the soleus, MG, and LG would be expected to produce approximately 71, 22, and 7% of the force and 54, 30, and 16% of the power of the major plantarflexors. These data illustrate some of the major limitations in the use of ACSA measurements to predict the functional properties of a muscle. C1 UNIV CALIF LOS ANGELES,SCH MED,CTR HLTH SCI,BRAIN RES INST,10833 LE CONTE AVE,LOS ANGELES,CA 90024. UNIV CALIF LOS ANGELES,DEPT PHYSIOL SCI,LOS ANGELES,CA 90024. JET PROP LAB,PASADENA,CA 91109. UNIV CALIF LOS ANGELES,DEPT RADIOL SCI,LOS ANGELES,CA 90024. UNIV TOKYO,DEPT SPORTS SCI,TOKYO 113,JAPAN. CEDARS SINAI MED CTR,CTR TOWER MUSCULOSKELETAL IMAGING,MAGNET RESONANCE IMAGING SECT,LOS ANGELES,CA 90048. RI fukunaga, tetsuo/C-6635-2009 NR 37 TC 123 Z9 124 U1 2 U2 18 PU JOURNAL BONE JOINT SURGERY INC PI NEEDHAM PA 20 PICKERING ST, NEEDHAM, MA 02192 SN 0736-0266 J9 J ORTHOPAED RES JI J. Orthop. Res. PD NOV PY 1992 VL 10 IS 6 BP 926 EP 934 DI 10.1002/jor.1100100623 PG 9 WC Orthopedics SC Orthopedics GA JW456 UT WOS:A1992JW45600022 ER PT J AU PALASZEWSKI, B AF PALASZEWSKI, B TI METALLIZED PROPELLANTS FOR THE HUMAN EXPLORATION OF MARS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Advanced chemical propulsion using metallized propellants can enable significant launch mass reductions for piloted Mars missions. Metallized propellants allow the density and/or the specific impulse (I(sp)) of the propulsion system to increase. These density and I(sp) increases can reduce the propellant mass and the propulsion system dry mass. Both of these effects are discussed and analyzed in the paper. Detailed mass scaling equations and estimates of the I(sp) for the metallized propellant combinations are presented. The most significant savings with metallized propellants are derived from increasing the payload delivered to Mars. For the same mass in low Earth orbit (LEO), a metallized Mars vehicle can deliver 20-22% additional payload to the surface. Using metallized propulsion can accelerate the delivery and construction of a Mars base or outpost. This 20% payload increase reduces the total number of Mars flights and, therefore, significantly reduces the number of space transportation system-cargo (STS-C) launches for the entire Mars architecture. Using metallized propellants to reduce the mass in LEO per flight is not as effective as increasing the payload delivery capacity. While over 20% more payload can be delivered to Mars per mission, the mass savings per flight (while delivering the same payload with a higher I(sp) system) is much smaller. Using metallized propellants in all of the Mars propulsion systems, a modest 3.3% LEO mass savings is possible. This translates into a savings of 38,000 kg over that required with O2/H2 propulsion. The Mars excursion vehicle (MEV) using Earth- or space-storable propellants for the ascent can be an alternative to storing cryogenic H-2 on Mars. There will be a mass penally for using these alternatives because of the lower I(sp) of these systems. A space-storable system using oxygen/monomethyl hydrazine/aluminum (O2/MMH/Al) delivered the lowest mass penalty over O2/H2. For the expedition case missions, the LEO mass penalty for using metallized O2/MMH/Al is only 3-5%. RP PALASZEWSKI, B (reprint author), NASA,LEWIS RES CTR,DIV SPACE PROPULS TECHNOL,METALLIZED PROPELLANT PROGRAM,CLEVELAND,OH 44135, USA. NR 22 TC 13 Z9 14 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 NOV-DEC PY 1992 VL 8 IS 6 BP 1192 EP 1199 DI 10.2514/3.11461 PG 8 WC Engineering, Aerospace SC Engineering GA JY976 UT WOS:A1992JY97600010 ER PT J AU ANDERSON, BH HUANG, PS PASCHAL, WA CAVATORTA, E AF ANDERSON, BH HUANG, PS PASCHAL, WA CAVATORTA, E TI STUDY ON VORTEX FLOW-CONTROL OF INLET DISTORTION SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The present study demonstrates that the reduced Navier-Stokes code (RNS3D) can be used very effectively to develop a vortex generator installation for the purpose of minimizing the engine-face circumferential distortion by controlling the development of secondary flow. The computing times required are small enough that studies such as this are feasible within a design environment with all its constraints of time and costs. A series of design observations were made concerning the importance of various vortex generator design parameters in minimizing engine-face circumferential distortion. The study showed that vortex strength, generator scale, and secondary flowfield structure have a complicated and interrelated influence on the engine-face distortion, over and above the initial geometry and arrangement of the generators. Overall, the installed vortex generator performance was found to be a function of three categories of variables: 1) the inflow conditions, i.e., throat Mach number (inlet mass flow), Reynolds number, etc.; 2) the aerodynamic characteristics associated with the inlet duct; and 3) the design parameters related to the geometry, arrangement, and placement of the vortex generators within the inlet duct itself. C1 DEE HOWARD CO,SAN ANTONIO,TX 78217. RP ANDERSON, BH (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 10 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1992 VL 8 IS 6 BP 1266 EP 1272 DI 10.2514/3.11472 PG 7 WC Engineering, Aerospace SC Engineering GA JY976 UT WOS:A1992JY97600021 ER PT J AU SAVAGE, M MACKULIN, BJ COE, HH COY, JJ AF SAVAGE, M MACKULIN, BJ COE, HH COY, JJ TI MAXIMUM LIFE SPUR GEAR DESIGN SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Optimization procedures allow one to design a spur gear reduction for maximum life and other end-use criteria. A modified feasible directions search algorithm permits a wide variety of inequality constraints and exact design requirements to be met with low sensitivity to initial guess values. The optimization algorithm is described and the models for gear life and performance are presented. The algorithm is compact and has been programmed for execution on a desktop computer. In the program, the designer is given the opportunity to change the mathematical optimum to a more practical design for comparative evaluation. Two examples are presented to illustrate the method and its application. C1 NASA,LEWIS RES CTR,MECH SYST TECHNOL BRANCH,CLEVELAND,OH 44135. RP SAVAGE, M (reprint author), UNIV AKRON,DEPT MECH ENGN,AKRON,OH 44325, USA. NR 14 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1992 VL 8 IS 6 BP 1273 EP 1281 DI 10.2514/3.11473 PG 9 WC Engineering, Aerospace SC Engineering GA JY976 UT WOS:A1992JY97600022 ER PT J AU LEIFER, SD RAPP, D SAUNDERS, WA AF LEIFER, SD RAPP, D SAUNDERS, WA TI ELECTROSTATIC PROPULSION USING C60 MOLECULES SO JOURNAL OF PROPULSION AND POWER LA English DT Note ID CARBON; BUCKMINSTERFULLERENE; C-60; PHOTOPHYSICS; IONS; C70 C1 CALTECH,PASADENA,CA 91125. RP LEIFER, SD (reprint author), JET PROP LAB,MS 125-224,4800 OAK GROVE RD,PASADENA,CA 91109, USA. NR 30 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 NOV-DEC PY 1992 VL 8 IS 6 BP 1297 EP 1300 DI 10.2514/3.11476 PG 4 WC Engineering, Aerospace SC Engineering GA JY976 UT WOS:A1992JY97600025 ER PT J AU ROTHMAN, LS GAMACHE, RR TIPPING, RH RINSLAND, CP SMITH, MAH BENNER, DC DEVI, VM FLAUD, JM CAMYPEYRET, C PERRIN, A GOLDMAN, A MASSIE, ST BROWN, LR TOTH, RA AF ROTHMAN, LS GAMACHE, RR TIPPING, RH RINSLAND, CP SMITH, MAH BENNER, DC DEVI, VM FLAUD, JM CAMYPEYRET, C PERRIN, A GOLDMAN, A MASSIE, ST BROWN, LR TOTH, RA TI THE HITRAN MOLECULAR DATABASE - EDITIONS OF 1991 AND 1992 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID FAR-INFRARED-SPECTRUM; INTERACTING VIBRATIONAL-STATES; SPECTROSCOPIC LINE PARAMETERS; AIR-BROADENING COEFFICIENTS; ABSORPTION CROSS-SECTIONS; 720-NM WAVELENGTH REGION; HIGH-RESOLUTION SPECTRUM; DIODE-LASER MEASUREMENTS; WATER-VAPOR; TEMPERATURE-DEPENDENCE AB We describe in this paper the modifications, improvements, and enhancements to the HITRAN molecular absorption database that have occurred in the two editions of 1991 and 1992. The current database includes line parameters for 31 species and their isotopomers that are significant for terrestrial atmospheric studies. This line-by-line portion of HITRAN presently contains about 709,000 transitions between 0 and 23,000 cm-1 and contains three molecules not present in earlier versions: COF2, SF6, and H2S. The HITRAN compilation has substantially more information on chlorofluorocarbons and other molecular species that exhibit dense spectra which are not amenable to line-by-line representation. The user access of the database has been advanced, and new media forms are now available for use on personal computers. C1 UNIV MASSACHUSETTS,CTR ATMOSPHER RES,LOWELL,MA 01854. UNIV ALABAMA,DEPT PHYS & ASTRON,TUSCALOOSA,AL 35487. NASA,LANGLEY RES CTR,CHEM & DYNAM BRANCH,HAMPTON,VA 23681. COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23187. UNIV PARIS 06,PHYS MOLEC & APPLICAT LAB,CNRS,F-75252 PARIS,FRANCE. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. JET PROP LAB,PASADENA,CA 91109. RP ROTHMAN, LS (reprint author), PHILLIPS LAB,GEOPHYS DIRECTORATE,BEDFORD,MA 01731, USA. OI Rothman, Laurence/0000-0002-3837-4847 NR 149 TC 1375 Z9 1381 U1 4 U2 50 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 469 EP 507 DI 10.1016/0022-4073(92)90115-K PG 39 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200002 ER PT J AU DEVI, VM BENNER, DC RINSLAND, CP SMITH, MAH AF DEVI, VM BENNER, DC RINSLAND, CP SMITH, MAH TI MEASUREMENTS OF PRESSURE BROADENING AND PRESSURE SHIFTING BY NITROGEN IN THE 4.3-MU-M BAND OF (CO2)-C-12-O-16 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID DIODE-LASER MEASUREMENTS; CO2 IR LINES; CARBON-DIOXIDE; HALF-WIDTHS; MU-M; ABSORPTION; SPECTROSCOPY; SELF; INTENSITIES; TEMPERATURE AB Lorentz broadening and pressure-induced line-shift coefficients of 34 individual lines of the nu3 band of (CO2)-C-12-O-16 have been determined using nitrogen as the buffer gas. The parameters were derived from 0.01 cm-1 resolution infrared absorption spectra recorded at room temperature using the McMath Fourier transform spectrometer and a nonlinear, least-squares fitting algorithm. The results obtained are compared with available values reported in the literature. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. RP DEVI, VM (reprint author), COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23187, USA. NR 39 TC 29 Z9 30 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 581 EP 589 DI 10.1016/0022-4073(92)90122-K PG 9 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200009 ER PT J AU FLAUD, JM CAMYPEYRET, C PERRIN, A RINSLAND, CP AF FLAUD, JM CAMYPEYRET, C PERRIN, A RINSLAND, CP TI IMPROVED SPECTROSCOPIC LINE PARAMETERS FOR THE OZONE MOLECULE SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article AB We present a summary of the O3 line parameters. The present status is first described, covering line positions, line intensities and linewidths, both for the main isotopic species O-16(3) and the isotopic variants O-16O-18O-16 and O-16O-16O-18. The second part of the paper deals with needed future studies. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. RP FLAUD, JM (reprint author), UNIV PARIS 06,PHYS MOLEC & APPLICAT LAB,CNRS,BTE 76,4 PL JUSSIEU,F-75252 PARIS 05,FRANCE. NR 6 TC 13 Z9 13 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 611 EP 615 DI 10.1016/0022-4073(92)90125-N PG 5 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200012 ER PT J AU BROWN, LR MARGOLIS, JS CHAMPION, JP HILICO, JC JOUVARD, JM LOETE, M CHACKERIAN, C TARRAGO, G BENNER, DC AF BROWN, LR MARGOLIS, JS CHAMPION, JP HILICO, JC JOUVARD, JM LOETE, M CHACKERIAN, C TARRAGO, G BENNER, DC TI METHANE AND ITS ISOTOPES - CURRENT STATUS AND PROSPECTS FOR IMPROVEMENT SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID BROADENED LORENTZ HALFWIDTHS; INDUCED LINE SHIFTS; 6-10 MU-M; TEMPERATURE-DEPENDENCE; HALF-WIDTHS; NU-3 BAND; INTENSITIES; (CH4)-C-13; (CH3D)-C-12; PARAMETERS AB The compilations of molecular line parameters of methane are continually being updated and improved. In the present article, numerous changes made for the 1991 and 1992 versions of the HITRAN database in the 0-6185 cm-1 region are described. An assessment of the deficiencies in the parameters is also given. C1 UNIV BOURGOGNE,SPECTRONOMIE MOLEC & INSTRUMENTAT LASER LAB,F-21000 DIJON,FRANCE. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV PARIS 11,PHYS MOLES & APPLICAT LAB,CNRS,F-91405 ORSAY,FRANCE. COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23187. RP BROWN, LR (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. RI Champion, Jean-Paul/C-3963-2009 NR 49 TC 45 Z9 45 U1 2 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 617 EP 628 DI 10.1016/0022-4073(92)90126-O PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200013 ER PT J AU GOLDMAN, A RINSLAND, CP AF GOLDMAN, A RINSLAND, CP TI HNO3 LINE PARAMETERS - NEW RESULTS AND COMPARISONS OF SIMULATIONS WITH HIGH-RESOLUTION LABORATORY AND ATMOSPHERIC SPECTRA SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID INFRARED-SPECTRUM; BAND; INTENSITIES; MILLIMETER; POSITIONS AB Updated line parameters for the HNO3 nu9, nu6, nu7, nu8, nu8 + nu9, nu2, nu3/nu4, and vs/2nu9 bands are reviewed. Simulations generated with the new line parameters are presented and compared with high-resolution atmospheric and laboratory spectra. Discussion of ongoing studies and needs for further improvements are included. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. RP GOLDMAN, A (reprint author), UNIV DENVER,DEPT PHYS,DENVER,CO 80208, USA. NR 14 TC 19 Z9 19 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 653 EP 666 DI 10.1016/0022-4073(92)90129-R PG 14 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200016 ER PT J AU CHACKERIAN, C GOORVITCH, D BENIDAR, A FARRENQ, R GUELACHVILI, G MARTIN, PM ABRAMS, MC DAVIS, SP AF CHACKERIAN, C GOORVITCH, D BENIDAR, A FARRENQ, R GUELACHVILI, G MARTIN, PM ABRAMS, MC DAVIS, SP TI ROVIBRATIONAL INTENSITIES AND ELECTRIC-DIPOLE MOMENT FUNCTION OF THE X(2)PI HYDROXYL RADICAL SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID TRANSITION-PROBABILITIES; OH; EMISSION AB We review the recent progress which has been made in determining absolute rovibrational intensities for the ground electronic state of the hydroxyl radical. We also discuss our own progress towards verifying the previous theoretical and experimental work. To this latter end, we will utilize two new sets of Fourier transform emission spectra of OH. One set of these spectra was recorded at the University of Paris at Orsay and the other at the National Solar Observatory, Kitt Peak, AZ. C1 UNIV PARIS 11,PHYS MOLEC & APPLICAT LAB,CNRS,F-91405 ORSAY,FRANCE. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. RP CHACKERIAN, C (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI benidar, abdessamad/O-1624-2014 NR 30 TC 8 Z9 8 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 667 EP 673 DI 10.1016/0022-4073(92)90130-V PG 7 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200017 ER PT J AU RINSLAND, CP GOLDMAN, A AF RINSLAND, CP GOLDMAN, A TI SEARCH FOR INFRARED-ABSORPTION LINES OF ATMOSPHERIC CHLORINE MONOXIDE (CLO) SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID INSITU OBSERVATIONS; OZONE-LAYER; STRATOSPHERE; INTENSITIES; POSITIONS; LATITUDE; BANDS; OH AB A search for features of the ClO (1-0) vibration-rotation band has been conducted based on a 5000 signal-to-r.m.s. noise ratio infrared (i.r.) spectrum derived by coadding 39 high-quality 0.0053-cm-1 resolution solar spectra recorded with the McMath Fourier transform spectrometer on Kitt Peak. Evidence for absorption has been found at the locations of several of the stronger ClO P-branch lines with minimal interference. Detailed results are presented for the P(8.5) and P(7.5) 2PI3/2-2PI3/2 lines of (CIO)-C-35 at 833.2974 and 834.6249 CM-1, respectively. If ClO is present in the stratosphere at the concentrations indicated by other methods, our analysis indicates that modest improvements in signal-to-noise ratio and spectral resolution would permit a definitive detection of ClO in i.r. ground-based spectra. C1 UNIV DENVER,DEPT PHYS,DENVER,CO 80208. RP RINSLAND, CP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. NR 34 TC 13 Z9 13 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 685 EP 692 DI 10.1016/0022-4073(92)90132-N PG 8 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200019 ER PT J AU RINSLAND, CP GOLDMAN, A FLAUD, JM AF RINSLAND, CP GOLDMAN, A FLAUD, JM TI INFRARED SPECTROSCOPIC PARAMETERS OF COF2, SF6, CLO, N2, AND O2 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID CARBONYL FLUORIDE; CHLORINE MONOXIDE; SULFUR-HEXAFLUORIDE; LOWER STRATOSPHERE; BAND; SPECTRA AB The spectroscopy of the infrared bands of COF2, SF6, ClO, N2, and O2 Is reviewed. Based on recent work, several improved sets of spectroscopic parameters have been generated and are included in the 1991 and 1992 versions of the HITRAN database. Anticipated future improvements and areas in need of further work are discussed. C1 UNIV DENVER,DEPT PHYS,DENVER,CO 80208. UNIV PARIS 06,PHYS MOLEC & APPLICAT LAB,CNRS,PARIS,FRANCE. RP RINSLAND, CP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. NR 33 TC 13 Z9 13 U1 1 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 693 EP 699 DI 10.1016/0022-4073(92)90133-O PG 7 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200020 ER PT J AU MAY, RD AF MAY, RD TI LINE-INTENSITIES AND COLLISIONAL-BROADENING PARAMETERS FOR THE NU-4 AND NU-6 BANDS OF CARBONYL FLUORIDE SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID DIODE-LASER SPECTROMETER; SOLAR OCCULTATION SPECTRA; LOWER STRATOSPHERE; COEFFICIENTS; POSITIONS AB Line intensities, air- and self-broadening parameters have been measured for selected lines in the nu4 (1243 cm-1) and nu6 (774 cm-1) bands of carbonyl fluoride at 2% and 215 K using a tunable diode-laser spectrometer. Measured line intensities are in good agreement (+/- 6%) with recently reported values derived from rotational analyses of the nu4 and nu6 bands. The measured average air-broadening coefficient at 296 K also agrees well (+/- 5%) with N2-broadening coefficients determined from microwave studies, while the average self-broadening coefficient reported here is smaller than a previously reported value by 45%. RP MAY, RD (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 9 Z9 9 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV-DEC PY 1992 VL 48 IS 5-6 BP 701 EP 712 DI 10.1016/0022-4073(92)90134-P PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KB742 UT WOS:A1992KB74200021 ER PT J AU MINNETYAN, L CHAMIS, CC MURTHY, PLN AF MINNETYAN, L CHAMIS, CC MURTHY, PLN TI STRUCTURAL DURABILITY OF A COMPOSITE PRESSURE-VESSEL SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article ID FRACTURE AB The effect of local ply fiber fracture on the load carrying capability and structural behavior of a composite cylindrical shell under internal pressure is investigated. An integrated computer code is utilized for the simulation of composite structural degradation under loading. Damage initiation, growth, accumulation, and propagation to structural fracture are included in the simulation. Results demonstrate the significance of local defects on the structural durability of pressurized composite cylindrical shells. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP MINNETYAN, L (reprint author), CLARKSON UNIV,POTSDAM,NY 13699, USA. NR 8 TC 11 Z9 11 U1 0 U2 1 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 NOV PY 1992 VL 11 IS 11 BP 1251 EP 1269 DI 10.1177/073168449201101103 PG 19 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA JY426 UT WOS:A1992JY42600003 ER PT J AU RUFFIN, SM VENKATAPATHY, E KEENER, ER SPAID, FW AF RUFFIN, SM VENKATAPATHY, E KEENER, ER SPAID, FW TI HYPERSONIC SINGLE EXPANSION RAMP NOZZLE SIMULATIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The single-expansion ramp-nozzle experiment underway al NASA Ames Research Center simulates the National Aerospace Plane propulsive jet-plume now. Recently, limited experimental data have become available from an experiment with a generic nozzle/afterbody model in a hypersonic wind tunnel. The present paper presents full three-dimensional solutions obtained with the implicit Navier-Stokes solver, FL3D, for the baseline model and a version of the model with side extensions. Analysis of the computed flow clearly shows the complex three-dimensional nature of the flow, critical flow features, and the effect of side extensions on the plume now development. Schematics of the flowfield appropriate for the conditions tested are presented for the baseline model and the model with side extensions. The computed results show excellent agreement with experimental shadowgraph and with surface pressure measurements. The computed and experimental surface oil flows show the same features but may be improved by appropriate turbulence modeling. C1 ELORET INST,PALO ALTO,CA 94303. MCDONNELL DOUGLAS CORP,SERV,ST LOUIS,MO 63166. RP RUFFIN, SM (reprint author), NASA,AMES RES CTR,DIV THERMOSCI,AEROTHERMODYNAM,MOFFETT FIELD,CA 94035, USA. NR 10 TC 3 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 NOV-DEC PY 1992 VL 29 IS 6 BP 749 EP 755 DI 10.2514/3.25527 PG 7 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400001 ER PT J AU STRAWA, AW PARK, C DAVY, WC BABIKIAN, DS PRABHU, DK AF STRAWA, AW PARK, C DAVY, WC BABIKIAN, DS PRABHU, DK TI PROPOSED RADIOMETRIC MEASUREMENT OF THE WAKE OF A BLUNT AEROBRAKE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This paper describes the aerothermal environment in the afterbody region of a blunt entry body. Recent ground-based experiments and computational predictions of the afterbody flow structure and radiation are presented. The similarity between the flowfield structures observed in the ground-based experiments and that obtained by calculation is encouraging. Approximate calculations of the radiative heating rate to the base are presented. Many of the phenomena associated with the expanding flow at the corner and the formation of the wake neck, however, are not well understood and require further study. A flight experiment is described that would use spectral and total measurements of the wake radiation as a nonintrusive diagnostic method to provide insight into the thermodynamic state of the wake gas. C1 ELORET INST,PALO ALTO,CA 94303. RP STRAWA, AW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 31 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1992 VL 29 IS 6 BP 765 EP 772 DI 10.2514/3.25529 PG 8 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400003 ER PT J AU CARLSON, AB WILMOTH, RG AF CARLSON, AB WILMOTH, RG TI SHOCK INTERFERENCE PREDICTION USING DIRECT SIMULATION MONTE-CARLO SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The direct simulation Monte Carlo (DSMC) method is used to model the flowfield produced when an incident shock impinges on an inlet cowl lip of 0.1-in. radius for flight conditions of approximately Mach 15 and 35-km altitude. The shock interaction results in a supersonic jet which can impinge on the cowl lip surface and cause extremes in surface heat transfer and pressure. Although this is a nonstandard application, DSMC offers two major advantages to the computational modeling of this problem over other schemes. The basic flow physics is simulated without the imposition of the continuum assumption, and the modeling of finite-rate chemistry is straightforward with a relatively small computational time penalty. The details of the simulation are presented with preliminary results for surface properties. RP CARLSON, AB (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,MS 366,HAMPTON,VA 23665, USA. NR 8 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 NOV-DEC PY 1992 VL 29 IS 6 BP 780 EP 785 DI 10.2514/3.25531 PG 6 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400005 ER PT J AU WILMOTH, RG DOGRA, VK MOSS, JN AF WILMOTH, RG DOGRA, VK MOSS, JN TI ENERGETICS OF GAS-SURFACE INTERACTIONS IN TRANSITIONAL FLOWS AT ENTRY VELOCITIES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The direct simulation Monte Carlo (DSMC) method has been used to calculate the molecular speed and energy distributions of molecules striking a surface after traversing a shock layer in hypersonic transitional flow. The calculations were performed for a 1.6-m-diam sphere at a nominal velocity for re-entry of 7.5 km/s over an altitude range of 130-90 km. Real gas effects and chemical reactions were included in the DSMC simulations. Results are presented for these conditions and the need for gas-surface interaction experiments is discussed. C1 VIGYAN RES ASSOCIATES INC,HAMPTON,VA 23666. RP WILMOTH, RG (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 13 TC 2 Z9 2 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 NOV-DEC PY 1992 VL 29 IS 6 BP 786 EP 793 DI 10.2514/3.25532 PG 8 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400006 ER PT J AU STRIEPE, SA NEALY, JE SIMONSEN, LC AF STRIEPE, SA NEALY, JE SIMONSEN, LC TI RADIATION EXPOSURE PREDICTIONS FOR SHORT-DURATION STAY MARS MISSIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The human radiation environment for several short-duration stay manned Mars missions is predicted using the Mission Radiation Calculation (MIRACAL) program. which was developed at NASA Langley Research Center. This program provides dose estimates for galactic cosmic rays (GCR) and large and ordinary solar proton flare events for various amounts of effective spacecraft shielding (both operational and storm shelter thicknesses) and a given time history of the spacecraft's heliocentric position. The results of this study show that most of the missions can survive the most recent large flares (if they were to occur at the missions perihelion) if a 25 g/cm2 storm shelter is assumed. The dose predictions show that missions during solar minima (when solar flare activity is the lowest) are not necessarily the minimum dose cases, due to increased GCR contribution during this time period. The direct transfer mission studied has slightly lower doses than the outbound Venus swingby mission [on the order of 10-20 centi-Sieverts (cSv) lower], with the greatest dose differences for the assumed worst case scenario (when the large nares occur at perihelion). The GCR dose for a mission can be reduced by having the crew spend some fraction of its day nominally in the storm shelter (other than during flare events). RP STRIEPE, SA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 21 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 NOV-DEC PY 1992 VL 29 IS 6 BP 801 EP 807 DI 10.2514/3.25534 PG 7 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400008 PM 11538210 ER PT J AU LYNE, JE TAUBER, ME BRAUN, RD AF LYNE, JE TAUBER, ME BRAUN, RD TI PARAMETRIC STUDY OF MANNED AEROCAPTURE .1. EARTH RETURN FROM MARS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A parametric study of the Earth return aerocapture for a manned Mars mission is described. The variation of entry corridor width and stagnation-point heating with vehicle arrival velocity, lift-to-drag ratio (L/D), and ballistic coefficient (m/C(D)A) are examined. To maximize corridor widths, the aerocapture maneuvers employ variable bank-angle trajectories. Vehicles with an LID of 0.5 or more are found to provide a corridor width of at least 0.7 deg while keeping the peak deceleration load below 5 g for approach velocities up to 14.5 km/s. Vehicle convective heating calculations are performed assuming a fully catalytic ''cold'' wall; radiative heating is computed assuming that the shock layer is in thermochemical equilibrium. As expected, heating rates are great enough to require ablative thermal protection systems in ali cases. Stagnation-point peak heating rates and integrated heat load are shown to depend critically on both entry velocity and ballistic coefficient. For the most severe cases considered, peak heating and integrated heat load are several times greater than those encountered by Apollo but within the range of experience for unmanned vehicles. C1 NASA,AMES RES CTR,DIV THERMOSCI,MOFFETT FIELD,CA 94035. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP LYNE, JE (reprint author), ELORET INST,DIV THERMOSCI,PALO ALTO,CA 94303, USA. RI Lyne, James/E-6363-2011 NR 23 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1992 VL 29 IS 6 BP 808 EP 813 DI 10.2514/3.25535 PG 6 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400009 ER PT J AU LYNE, JE ANAGNOST, A TAUBER, ME AF LYNE, JE ANAGNOST, A TAUBER, ME TI PARAMETRIC STUDY OF MANNED AEROCAPTURE .2. MARS ENTRY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A parametric study of aerocapture for manned Mars missions has been conducted. The variation of entry corridor width and stagnation-point heating with vehicle entry velocity, ballistic coefficient, and lift-to-drag ratio were examined. To maximize corridor widths, the aerocapture maneuvers employed variable bank-angle trajectories. Vehicles with an LID of 0.4-0.5 were found to provide an entry corridor width of at least 1 deg for approach velocities up to 10 km/s. Vehicle convective heating calculations were performed assuming a fully catalytic ''cold'' wall; radiative heating was computed assuming that the shock layer was in thermochemical equilibrium. It was found that for entry velocities below approximately 7 km/s, radiative cooling may be possible for the thermal protection system. At higher entry speeds, ablative heat shields must be used. Maximum integrated stagnation-point heat loads were found to be equivalent to or less than those experienced by the Space Shuttle on a typical re-entry. C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. NASA,AMES RES CTR,DIV THERMOSCI,MOFFETT FIELD,CA 94035. RP LYNE, JE (reprint author), ELORET INST,DIV THERMOSCI,PALO ALTO,CA 94303, USA. RI Lyne, James/E-6363-2011 NR 15 TC 4 Z9 4 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 NOV-DEC PY 1992 VL 29 IS 6 BP 814 EP 819 DI 10.2514/3.25536 PG 6 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400010 ER PT J AU BRODY, AR JACOBY, R ELLIS, SR AF BRODY, AR JACOBY, R ELLIS, SR TI EXTRAVEHICULAR ACTIVITY SELF-RESCUE USING A HAND-HELD THRUSTER SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID TRAJECTORY PLANNING TOOL; ARTIFICIAL WORLD; LOOKING-GLASS; INTERFACES; COMPUTER; EIVAN AB A study was performed in the virtual interactive environment workstation. Simulations were conducted to assess the feasibility and quantify the fuel and time requirements for a stranded crewperson to return to a space station after an accidental separation. A hand-held thruster, similar to the hand-held maneuvering unit from the Gemini program, was used for propulsion. Thirty different separation scenarios were composed of three separation rates, five initial spin rates, and an opportunity to use an attitude hold device in a repeated measures design. Statistically significant results were produced by separation velocity. Fuel, time maximum range, time to maximum range, maximum axial range, and final axial velocity increased with separation rate. A hand-held thruster is a viable alternative for accomplishing a self-rescue. Although one cannot prove a null effect, the fact that an attitude hold capability did not decrease solution time or fuel consumption is important for system designers. This fact, coupled with the success of a hand-held thruster in simulations, suggests that the added expense of more sophisticated solutions requiring a multitude of thrusters-and higher computation and power capabilities-may be unwarranted. C1 STERLING SOFTWARE,PALO ALTO,CA 94303. RP BRODY, AR (reprint author), NASA,AMES RES CTR,NASA AMES DIV,MS 262-2,MOFFETT FIELD,CA 94035, USA. NR 35 TC 3 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 NOV-DEC PY 1992 VL 29 IS 6 BP 842 EP 848 DI 10.2514/3.25540 PG 7 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400014 ER PT J AU KORTE, JJ AF KORTE, JJ TI AERODYNAMIC DESIGN OF AXISYMMETRICAL HYPERSONIC WIND-TUNNEL NOZZLES USING A LEAST-SQUARES PARABOLIZED NAVIER-STOKES PROCEDURE (J SPACECRAFT, VOL 29, PG 685, 1992) SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Correction, Addition RP KORTE, JJ (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 1 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 NOV-DEC PY 1992 VL 29 IS 6 BP 870 EP 871 DI 10.2514/3.55647 PG 2 WC Engineering, Aerospace SC Engineering GA KE254 UT WOS:A1992KE25400017 ER PT J AU OGBUJI, LUJT AF OGBUJI, LUJT TI ROLE OF SI2N2O IN THE PASSIVE OXIDATION OF CHEMICALLY-VAPOR-DEPOSITED SI3N4 SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID SILICON-NITRIDE; SI; CERAMICS; CARBIDE AB The results of two-step oxidation experiments on chemically-vapor-deposited Si3N4 and SiC at 1350-degrees-C show that a correlation exists between the presence of a Si2N2O interphase and the strong oxidation resistance of Si3N4. During normal oxidation, k(p) for SiC was 15 times higher than that for Si3N4, and the oxide scale on Si3N4 was found by SEM and TEM to contain a prominent Si2N2O inner layer. However, when oxidized samples are annealed in Ar for 1.5 h at 1500-degrees-C and reoxidized at 1350-degrees-C as before, three things happen: the oxidation k(p) increases over 55-fold for Si3N4, and 3.5-fold for SiC; the Si3N4 and SiC oxidize with nearly equal k(p)'s; and, most significant, the oxide scale on Si3N4 is found to be lacking an inner Si2N2O layer. The implications of this correlation for the competing models of Si3N4 oxidation are discussed. RP OGBUJI, LUJT (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 27 TC 43 Z9 45 U1 0 U2 5 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD NOV PY 1992 VL 75 IS 11 BP 2995 EP 3000 DI 10.1111/j.1151-2916.1992.tb04377.x PG 6 WC Materials Science, Ceramics SC Materials Science GA JX136 UT WOS:A1992JX13600014 ER PT J AU BEGAULT, DR AF BEGAULT, DR TI PERCEPTUAL EFFECTS OF SYNTHETIC REVERBERATION ON 3-DIMENSIONAL AUDIO SYSTEMS SO JOURNAL OF THE AUDIO ENGINEERING SOCIETY LA English DT Article ID HEADPHONE SIMULATION; HEAD RECORDINGS; SPECTRAL CUES; LOCALIZATION; SOUND; PLANE AB A psychoacoustic investigation was conducted in which five subjects gave localization judgments for headphone-delivered speech stimuli processed by nonindividualized head-related transfer functions, with and without synthetic "spatial" reverberation added to the stimuli. Spatial reverberation minimized intracranially heard stimuli, but increased the magnitude of azimuth and elevation localization errors. The results are applicable to three-dimensional sound systems and spatial sound field processors designed to increase the sensation of auditory "spaciousness". RP BEGAULT, DR (reprint author), NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035, USA. NR 37 TC 30 Z9 31 U1 0 U2 1 PU AUDIO ENGINEERING SOC PI NEW YORK PA 60 E 42ND ST, NEW YORK, NY 10165-2520 SN 0004-7554 J9 J AUDIO ENG SOC JI J. Audio Eng. Soc. PD NOV PY 1992 VL 40 IS 11 BP 895 EP 904 PG 10 WC Acoustics; Engineering, Multidisciplinary SC Acoustics; Engineering GA KA265 UT WOS:A1992KA26500003 ER PT J AU NAGASUBRAMANIAN, G ATTIA, AI HALPERT, G AF NAGASUBRAMANIAN, G ATTIA, AI HALPERT, G TI EFFECTS OF 12-CROWN-4 ETHER ON THE ELECTROCHEMICAL PERFORMANCE OF COO2 AND TIS2 CATHODES IN LI POLYMER ELECTROLYTE CELLS SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID TEMPERATURE AB Polyethylene oxide (PEO) electrolytes appear stable in the potential range of 2.2 to 5.5 V vs. Li and the addition of 12-Crown-4 Ether (12Cr4) to enhance their conductivity does not seem to alter the electrochemical potential window. The dc cyclic voltammogram of cells of the type Li/PEO electrolyte(a)/LixCoO2 b at low scan rate (1 mV/s) exhibits well-defined cathodic and anodic peaks in the potential range from 2.2 to 5.5 V. The additive 12Cr4 improves the electrochemical performance of the cells as evidenced by lower peak splitting, higher current, and higher reversibility over many voltage scans. The open-circuit voltage (OCV) of a freshly assembled cell in the discharged state is in the range from 3.5 to 3.7 V. Upon charging at the C/180 rate, which mimics a titration experiment (OCV vs. cathode composition), the OCV rises sharply to 4.1 V at Li0.93CoO2 then gradually increases to 4.4 V at Li0.3CoO2. The titration curves are similar for cells with and without 12Cr4 in the electrolyte. The long term ac behavior of the cells (three-electrode configuration with 0.7 cm2 Li counter; 0.06 cm2 LixCoO2 b working; and Li reference) shows that the addition of 12Cr4 reduces the bulk and interfacial charge-transfer resistances but does not prolong the active life of the cells. While the cells with CoO2 as the cathode fail after a couple of galvanostatic charge/discharge (c/d) cycles similar cells with TiS2 did not fail even after 12 c/d cycles. As in the case of cells containing CoO2 as cathode, 12Cr4 in the electrolyte improves the electrochemical performance of cells with TiS2 as cathodes. The probable cause of failure in the case of CoO2 is ascribed to the instability of the CoO2 cathode. RP NAGASUBRAMANIAN, G (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 10 TC 20 Z9 20 U1 1 U2 7 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 NOV PY 1992 VL 139 IS 11 BP 3043 EP 3046 DI 10.1149/1.2069030 PG 4 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA JX172 UT WOS:A1992JX17200011 ER PT J AU JUNG, KH SHIH, S KWONG, DL GEORGE, T LIN, TL LIU, HY ZAVADA, J AF JUNG, KH SHIH, S KWONG, DL GEORGE, T LIN, TL LIU, HY ZAVADA, J TI PHOTOLUMINESCENCE, STRUCTURE, AND COMPOSITION OF LATERALLY ANODIZED POROUS SI SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID INTENSE PHOTOLUMINESCENCE; SILICON; ELECTROLUMINESCENCE; FILMS AB We have studied the photoluminescence (PL), structure, and composition of laterally anodized porous Si. Broad PL peaks were observed centered between approximately 620-720 nm with strong intensities measured from 500 to 860 nm. Macroscopic variations in PL intensities and peak positions are explained in terms of the structure and anodization process. Structural studies suggest that the PL appears to originate from a multilayered porous Si structure in which the top two layers are amorphous. X-ray diffraction spectra also suggest the presence of a significant amorphous phase. In addition to high concentrations of B and N, we have measured extremely high concentrations (>> 10(20) cm-3) of H, C, O, and F. Our results indicate that laterally anodized porous Si does not fit the crystalline Si quantum wire model prevalent in the literature, suggesting that some other structure is responsible for the observed luminescence. C1 JET PROP LAB,CTR SPACE MICROELECTR,PASADENA,CA 91109. TEXAS INSTRUMENTS INC,DALLAS,TX 75265. USA,RES OFF,RES TRIANGLE PK,NC 27709. RP JUNG, KH (reprint author), UNIV TEXAS,DEPT ELECT & COMP ENGN,MICROELECTR RES CTR,AUSTIN,TX 78712, USA. NR 49 TC 25 Z9 25 U1 0 U2 0 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 NOV PY 1992 VL 139 IS 11 BP 3363 EP 3372 DI 10.1149/1.2069079 PG 10 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA JX172 UT WOS:A1992JX17200060 ER PT J AU THRALL, KD BULL, RJ SAUER, RL AF THRALL, KD BULL, RJ SAUER, RL TI DISTRIBUTION OF IODINE INTO BLOOD COMPONENTS OF THE SPRAGUE-DAWLEY RAT DIFFERS WITH THE CHEMICAL FORM ADMINISTERED SO JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH LA English DT Article AB It has been reported previously that radioactivity derived from iodine distributes differently in the Sprague-Dawley rat depending on the chemical form administered (Thrall and Bull, 1990). In the present communication we report the differential distribution of radioactivity derived from iodine (I2) and iodide (I-) into blood components. Twice as much radioiodine is in the form of I- in the plasma of animals treated with I-125- compared to I-125(2)-treated rats. No I2 could be detected in the plasma. With an increase in dose, increasing amounts of radioactivity derived from I-125(2)-treated animals distribute to whole blood compared to equivalent doses of I-125-, reaching a maxima at a dose of 15.8 mumol l/kg body weight. Most of the radioactivity derived from 12 associates with serum proteins and lipids, in particular with albumin and cholesteryl iodide. These data indicate a differential distribution of radioactivity depending on whether it is administered as iodide or iodine. This is inconsistent with the commonly held view that iodine (I2) is reduced to iodide (I-) before it is absorbed systemically from the gastrointestinal tract. C1 WASHINGTON STATE UNIV,COLL PHARM,PHARMACOL TOXICOL GRAD PROGRAM,PULLMAN,WA 99164. NASA,LYNDON B JOHNSON SPACE CTR,DIV SPACE & LIFE SCI,HOUSTON,TX 77058. NR 12 TC 12 Z9 12 U1 0 U2 0 PU TAYLOR & FRANCIS PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 0098-4108 J9 J TOXICOL ENV HEALTH JI J. Toxicol. Environ. Health PD NOV PY 1992 VL 37 IS 3 BP 443 EP 449 PG 7 WC Environmental Sciences; Public, Environmental & Occupational Health; Toxicology SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health; Toxicology GA JY411 UT WOS:A1992JY41100007 PM 1433379 ER PT J AU MAKER, PD MULLER, RE AF MAKER, PD MULLER, RE TI PHASE HOLOGRAMS IN POLYMETHYL METHACRYLATE SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article; Proceedings Paper CT 36TH ANNUAL INTERNATIONAL SYMP ON ELECTRON, ION, AND PHOTON BEAMS CY MAY 26-29, 1992 CL ORLANDO, FL SP AMER VACCUM SOC, IEEE, ELECTRON DEVICE SOC, OPT SOC AMER, HUGHES RES LABS ID ELECTRON-BEAM LITHOGRAPHY AB Complex computer generated phase holograms (CGPHs) have been fabricated in polymethyl methacrylate (PMMA) by partial exposure and subsequent partial development. The CGPH was encoded as a sequence of phase delay pixels and written by e-beam (JEOL JBX-5DII), a different dose being assigned to each value of phase delay. Following carefully controlled, partial development, the pattern appears, rendered in relief, in the PMMA which then acts as the phase-delay medium. The exposure dose was in the range 20-200 muC/cm2, and very aggressive development in pure acetone led to low contrast. This enabled etch depth control to better than +/-20 nm corresponding to an optical phase shift in transmission, relative to air, of +/-lambda(vis)/60. That result was obtained by exposing isolated 50 mum square patches and measuring resist removal over the central area where the proximity effect dose was uniform and related only to the local exposure. For complex CGPHs with pixel size of the order of the proximity radius, the patterns must be corrected for proximity effects. In addition, the isotropic nature of the development process will produce sidewall etching effects. The devices fabricated were designed with 16 equal phase steps per retardation cycle, were up to 3 mm square, and consisted of up to 10 million 0.3-2.0 mum square pixels. Data files were up to 60 Mb long and exposure times ranged to several hours. No sidewall etch corrections were applied to the pattern and proximity effects were only treated approximately. A Fresnel phase lens was fabricated that had diffraction limited optical performance with 83% efficiency. RP MAKER, PD (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 4 TC 29 Z9 29 U1 1 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 NOV-DEC PY 1992 VL 10 IS 6 BP 2516 EP 2519 DI 10.1116/1.586049 PG 4 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA KM500 UT WOS:A1992KM50000030 ER PT J AU MAEKAWA, H MANSOUR, NN AF MAEKAWA, H MANSOUR, NN TI DIRECT NUMERICAL SIMULATIONS OF A SPATIALLY DEVELOPING PLANE WAKE SO JSME INTERNATIONAL JOURNAL SERIES II-FLUIDS ENGINEERING HEAT TRANSFER POWER COMBUSTION THERMOPHYSICAL PROPERTIES LA English DT Article DE COMPUTATIONAL FLUID DYNAMICS; WAKE; TRANSITION; FINITE DIFFERENCE METHOD; TURBULENCE CONTROL; PSEUDOSPECTRAL FOURIER METHOD ID MIXING LAYERS; CHANNEL FLOW; NUMBER AB in the present paper, direct numerical methods by which to simulate the spatially developing free shear flows in the transitional region are described and the numerical results of a spatially developing plane wake are presented. The incompressible time-dependent Navier-Stokes equations were solved using Pade finite difference approximations in the streamwise direction, a mapped pseudospectral Fourier method in the cross-stream direction, and a third-order compact Runge-Kutta scheme for time advancement. The unstable modes of the Orr-Sommerfeld equations were used to perturb the inlet of the wake. Statistical analyses were performed and some numerical results were compared with experimental measurements. When only the fundamental mode is forced, the energy spectra show amplification of the fundamental and its higher harmonics. In this case, unperturbed alternate vortices develop in the saturation region of the wake. The phase jitter around the fundamental frequency plays a critical role in generating vortices of random shape and spacing. Large- and small-scale distortions of the fundamental structure are observed. Pairing of vortices of the same sign is observed, as well as vortex coupling of vortices of the opposite sign. C1 NASA,AMES RES CTR,CFD BRANCH,MOFFETT FIELD,CA 94035. RP MAEKAWA, H (reprint author), UNIV ELECTROCOMMUN,DEPT MECH & CONTROL ENGN,CHOFU,TOKYO 182,JAPAN. NR 18 TC 2 Z9 2 U1 0 U2 0 PU JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG PI TOKYO PA 4-9 YOYOGI 2-CHOME SHIBUYA-KU, TOKYO 151, JAPAN SN 0914-8817 J9 JSME INT J II-FLUID PD NOV PY 1992 VL 35 IS 4 BP 543 EP 548 PG 6 WC Engineering, Mechanical SC Engineering GA KD917 UT WOS:A1992KD91700009 ER PT J AU BOGDANSKI, MS SLINEY, HE DELLACORTE, C AF BOGDANSKI, MS SLINEY, HE DELLACORTE, C TI TRIBOLOGICAL AND MICROSTRUCTURAL COMPARISON OF HIPPED PM212 AND PM212/AU SELF-LUBRICATING COMPOSITES SO LUBRICATION ENGINEERING LA English DT Article ID COATINGS AB The feasibility of replacing the silver with the volumetric equivalent of gold in the chromium carbide-based, self-lubricating composite PM212 (70 wt% NiCo-Cr3C2, 15% Ag, 15% BaF2/CaF2 eutectic) was studied. The new composite, PM212/Au has the following composition: 62 wt% NiCo-Cr3C2, 25% Au, 13% BaF2/CaF2 eutectic. The silver was replaced with gold to minimize the potential reactivity of the composite with possible environmental contaminants, such as sulfur. The composites were fabricated by hop isostatic pressing (HIPping) and machined into pin specimens. The pins were slid against nickel-based superalloy disks. Sliding velocities ranged from 0.27 to 10.0 m/sec and temperatures from 25 to 900-degrees-C. Friction coefficients ranged from 0.25 to 0.40 and wear factors for the pin and disk were typically low 10(-5)mm3/N-m. HIPped PM212 measured fully dense, whereas PM212/Au had 15 percent residual porosity. Examination of the microstructures with optical and scanning electron microscopy revealed the presence of pores in PM212/Au that were not present in PM212. Though the exact reason for the residual porosity in PM212/Au was not determined, it may be due to particle morphology differences between the gold and silver and their effect on powder metallurgy processing. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOGDANSKI, MS (reprint author), CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106, USA. NR 11 TC 0 Z9 0 U1 0 U2 1 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD NOV PY 1992 VL 48 IS 11 BP 849 EP 856 PG 8 WC Engineering, Mechanical SC Engineering GA JW589 UT WOS:A1992JW58900003 ER PT J AU DELLACORTE, C SLINEY, HE BOGDANSKI, MS AF DELLACORTE, C SLINEY, HE BOGDANSKI, MS TI TRIBOLOGICAL AND MECHANICAL COMPARISON OF SINTERED AND HIPPED PM212 - HIGH-TEMPERATURE SELF-LUBRICATING COMPOSITES SO LUBRICATION ENGINEERING LA English DT Article DE SOLID LUBRICATION; COMPOSITES; HIGH TEMPERATURE; FRICTION; WEAR ID COMPOSITION OPTIMIZATION; COATINGS AB Selected tribological, mechanical and thermophysical properties of two versions of PM212, sintered and hot isostatically pressed, HIPped, are compared. PM212, a high temperature self-lubricating composite, contains 70 wt % metal bonded chromium carbide, 15 wt % CaF2/BaF2 eutetic and 15 wt % silver. In the sintered form, PM212 is about 80 percent dense and has previously been shown to have good tribological properties from room temperature to 850-degrees-C. This paper reports the tribological results of a fully densified, HIPped version of PM212 and compares them to sintered PM212. In addition, selected mechanical and thermophysical properties of both types of PM212 are discussed and related to the tribological similarities and differences between the two PM212 composites. In general, both composites display similar friction and wear properties. However, the fully dense PM212 HIPped composite exhibits slightly lower friction and wear sintered PM212. This may be attributed to its generally higher strength properties. The sintered version displays stable wear properties over a wide load range, indicating its promise for use in a variety of applications. Based upon their properties, both the sintered and the HIPped PM212 have potential as bearing and seal materials for advanced high-temperature applications. RP DELLACORTE, C (reprint author), NASA,LEWIS RES CTR,TRIBOL GRP,CLEVELAND,OH 44135, USA. NR 12 TC 16 Z9 19 U1 0 U2 2 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD NOV PY 1992 VL 48 IS 11 BP 877 EP 885 PG 9 WC Engineering, Mechanical SC Engineering GA JW589 UT WOS:A1992JW58900006 ER PT J AU CHANG, SW STEIMLE, FW REID, RN FROMM, SA ZDANOWICZ, VS PIKANOWSKI, RA AF CHANG, SW STEIMLE, FW REID, RN FROMM, SA ZDANOWICZ, VS PIKANOWSKI, RA TI ASSOCIATION OF BENTHIC MACROFAUNA WITH HABITAT TYPES AND QUALITY IN THE NEW-YORK BIGHT SO MARINE ECOLOGY PROGRESS SERIES LA English DT Article AB Previous qualitative and limited quantitative analyses of benthic data from the New York Bight, USA, have suggested associations among macrofauna and sediment characteristics, including levels of chemical contamination. Benthic data from 3 summers (1980 to 1982) of sampling were used to examine more thoroughly these relationships. Factor and canonical analyses confirmed that a limited group of macrofaunal taxa (Ceriantheopsis american us, Nephtys incisa, Capitella spp., Nucula proxima and Ampelisca agassizi), historically considered indicators of habitat quality, were indeed valid indicators. Ordination analyses provided greater detail about the association of, and between, sediment variables and the 80 most frequently occurring species. The results allowed a characterization of the New York Bight benthic habitat, encompassing the range from an undisturbed habitat to the lowest quality habitat. One species group was consistently associated with minimally contaminated sediments and appears to represent a basic natural benthic macrofaunal assemblage for the Bight. This group included taxa such as the sand dollar Echinarachnius parma and several species of amphipods (e.g. Byblis serrata, Corophium crassicorne and Ampelisca agassizi) as well as some polychaetes (e.g. Goniadella gracilis and Exogone hebes). Species that were the most common in the contaminated areas of the Bight were mainly polychaetes (e.g. Tharyx acutus, Nephtys incisa, Pherusa affinis and Capitella spp.) as well as the Nemertinea (Cerebratulus lacteus), an anemone (Ceriantheopsis americanus), a phoronid (Phoronis architecta) and the nut clam Nucula proxima. RP CHANG, SW (reprint author), US DEPT COMMERCE, NOAA, NATL MARINE FISHERIES SERV, NE FISHERIES CTR, SANDY HOOK LAB, HIGHLANDS, NJ 07732 USA. NR 33 TC 26 Z9 27 U1 0 U2 4 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0171-8630 J9 MAR ECOL PROG SER JI Mar. Ecol.-Prog. Ser. PD NOV PY 1992 VL 89 IS 2-3 BP 237 EP 251 DI 10.3354/meps089237 PG 15 WC Ecology; Marine & Freshwater Biology; Oceanography SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Oceanography GA KH346 UT WOS:A1992KH34600013 ER PT J AU HARDY, JT HOGE, FE YUNGEL, JK DODGE, RE AF HARDY, JT HOGE, FE YUNGEL, JK DODGE, RE TI REMOTE DETECTION OF CORAL BLEACHING USING PULSED-LASER FLUORESCENCE SPECTROSCOPY SO MARINE ECOLOGY PROGRESS SERIES LA English DT Article ID MONTASTREA-ANNULARIS; REEF CORALS; STYLOPHORA-PISTILLATA; TEMPERATURE; ZOOXANTHELLAE; CHLOROPHYLL; STRESS; PLANTS; CARBON; LIGHT AB Despite their biological and economic importance coral reefs are increasingly threatened by human activities. Recently, 'bleaching' of reefs, i.e. loss of photosynthetic pigmentation, has occurred at numerous globally-distributed sites. A number of environmental stressors, including increased water temperature, can induce bleaching. Several investigators have suggested that the widespread occurrence of coral bleaching represents an early warning signal of global greenhouse warming. Regardless of the cause, the extent of coral bleaching, both regionally and globally, needs to be documented and monitored. We conducted laboratory studies to evaluate the potential of using remotely-sensed laser-induced fluorescence to monitor coral pigmentation. Five species of Caribbean corals were collected, transported to the laboratory, and maintained in aquaria. Coral samples were irradiated at either 532 nm or 337 nm with pulsed-laser light and spectral scans of fluorescence were collected at 1 nm intervals. Distinct chlorophyll fluorescence peaks at 685 and 740 nm were observed in all species examined. In corals exposed to temperature-induced stress, incipient changes in the fluorescence spectra could be detected prior to visible bleaching and coral death. Remotely measured (aircraft or ship) laser-induced fluorescence provides a potentially useful tool for monitoring the pigmentation status of coral reefs. Field validation will be necessary, but our results suggest that it may be possible to distinguish bleaching, or even partial bleaching, over large geographical areas with sensitivity and rapidity. C1 NASA, GODDARD SPACE FLIGHT CTR, WALLOPS FLIGHT FACIL, WALLOPS ISL, VA 23337 USA. NOVA UNIV, CTR OCEANOG, DANIA, FL 33004 USA. EG&G INC, WASHINGTON ANALYT SERV, WALLOPS ISL, VA 23337 USA. RP HARDY, JT (reprint author), WESTERN WASHINGTON STATE UNIV, REG & GLOBAL STUDIES PROGRAM, MS9079, BELLINGHAM, WA 98225 USA. NR 39 TC 34 Z9 34 U1 0 U2 5 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0171-8630 J9 MAR ECOL PROG SER JI Mar. Ecol.-Prog. Ser. PD NOV PY 1992 VL 88 IS 2-3 BP 247 EP 255 DI 10.3354/meps088247 PG 9 WC Ecology; Marine & Freshwater Biology; Oceanography SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Oceanography GA KE423 UT WOS:A1992KE42300013 ER PT J AU BRAY, GH REYNOLDS, AP STARKE, EA AF BRAY, GH REYNOLDS, AP STARKE, EA TI MECHANISMS OF FATIGUE CRACK RETARDATION FOLLOWING SINGLE TENSILE OVERLOADS IN POWDER-METALLURGY ALUMINUM-ALLOYS SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID CLOSURE; GROWTH; BEHAVIOR AB In ingot metallurgy (IM) alloys, the number of delay cycles following a single tensile overload typically increases from a minimum at an intermediate baseline stress intensity range, DELTAK(B), with decreasing DELTAK(B) approaching threshold and increasing DELTAK(B) approaching unstable fracture to produce a characteristic "U"-shaped curve. Two models have been proposed to explain this behavior. One model is based on the interaction between roughness and plasticity-induced closure, while the other model only utilizes plasticity-induced closure. This article examines these models using experimental results from constant amplitude and single overload fatigue tests performed on two powder metallurgy (PM) aluminum alloys, AL-905XL and AA 8009. The results indicate that the "U"-shaped curve is primarily due to plasticity-induced closure, and that the plasticity-induced retardation effect is through-thickness in nature, occurring in both the surface and interior regions. However, the retardation effect is greater at the surface, because the increase in plastic strain at the crack tip and overload plastic zone size are larger in the plane-stress surface regions than in the plane-strain interior regions. These results are not entirely consistent with either of the proposed models. C1 NASA,LANGLEY RES CTR,ANALYT SERV & MAT INC,HAMPTON,VA 23665. RP BRAY, GH (reprint author), UNIV VIRGINIA,SCH ENGN & APPL SCI,CHARLOTTESVILLE,VA 22903, USA. RI Reynolds, Anthony/F-2585-2010 NR 24 TC 17 Z9 17 U1 1 U2 2 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD NOV PY 1992 VL 23 IS 11 BP 3055 EP 3066 DI 10.1007/BF02646123 PG 12 WC Materials Science, Multidisciplinary SC Materials Science GA JW151 UT WOS:A1992JW15100011 ER PT J AU YUN, HM TITRAN, RH AF YUN, HM TITRAN, RH TI TENSILE STRAIN-RATE SENSITIVITY OF TUNGSTEN NIOBIUM COMPOSITES AT 1300 TO 1600-K SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article AB The tensile strain-rate sensitivity of continuous-tungsten-fiber reinforced niobium composites (W/Nb), fabricated by an arc-spray process, was studied in the 1300 to 1600 K temperature range. The tensile properties of the fiber and matrix components, as well as of the composites, were measured and compared to rule of mixtures (ROM) predictions. The deviation from the ROM was found to depend upon the chemistry of the tungsten alloy fibers, with positive deviations for thoria-dispersed W wire (ST300) reinforced Nb composite (i.e., stronger composite strength than the ROM) and negative or zero deviations for lamp-grade W wire (218) reinforced Nb composite. In addition, it was found that the composites tested at higher crosshead speeds exhibited a strain-rate sensitivity greater than that of the free fibers tested at the same crosshead speeds, even though the composite tensile strength is determined mainly by the fiber component. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP YUN, HM (reprint author), CLEVELAND STATE UNIV,CLEVELAND,OH 44115, USA. NR 16 TC 1 Z9 2 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD NOV PY 1992 VL 23 IS 11 BP 3121 EP 3133 DI 10.1007/BF02646131 PG 13 WC Materials Science, Multidisciplinary SC Materials Science GA JW151 UT WOS:A1992JW15100019 ER PT J AU GOODMAN, RM HIGGINS, CM MILLER, JW SMYTH, P AF GOODMAN, RM HIGGINS, CM MILLER, JW SMYTH, P TI RULE-BASED NEURAL NETWORKS FOR CLASSIFICATION AND PROBABILITY ESTIMATION SO NEURAL COMPUTATION LA English DT Article AB In this paper we propose a network architecture that combines a rule-based approach with that of the neural network paradigm. Our primary motivation for this is to ensure that the knowledge embodied in the network is explicitly encoded in the form of understandable rules. This enables the network's decision to be understood, and provides an audit trail of how that decision was arrived at. We utilize an information theoretic approach to learning a model of the domain knowledge from examples. This model takes the form of a set of probabilistic conjunctive rules between discrete input evidence variables and output class variables. These rules are then mapped onto the weights and nodes of a feedforward neural network resulting in a directly specified architecture. The network acts as parallel Bayesian classifier, but more importantly, can also output posterior probability estimates of the class variables. Empirical tests on a number of data sets show that the rule-based classifier performs comparably with standard neural network classifiers, while possessing unique advantages in terms of knowledge representation and probability estimation. C1 JET PROP LAB,PASADENA,CA 91109. RP GOODMAN, RM (reprint author), CALTECH,DEPT ELECT ENGN,PASADENA,CA 91125, USA. NR 35 TC 38 Z9 38 U1 0 U2 0 PU MIT PRESS PI CAMBRIDGE PA 55 HAYWARD ST JOURNALS DEPT, CAMBRIDGE, MA 02142 SN 0899-7667 J9 NEURAL COMPUT JI Neural Comput. PD NOV PY 1992 VL 4 IS 6 BP 781 EP 804 DI 10.1162/neco.1992.4.6.781 PG 24 WC Computer Science, Artificial Intelligence; Neurosciences SC Computer Science; Neurosciences & Neurology GA JW950 UT WOS:A1992JW95000001 ER PT J AU FUJII, MD PATTEN, BM AF FUJII, MD PATTEN, BM TI NEUROLOGY OF MICROGRAVITY AND SPACE TRAVEL SO NEUROLOGIC CLINICS LA English DT Article ID CANADIAN VESTIBULAR EXPERIMENTS; SKELETAL-MUSCLE; PROLONGED WEIGHTLESSNESS; MOTION SICKNESS; EARTHS GRAVITY; FLIGHT; READAPTATION; SPACEFLIGHT; MISSION; FIBERS C1 BAYLOR COLL MED,DEPT NEUROL,HOUSTON,TX 77030. METHODIST HOSP,HOUSTON,TX 77030. RP FUJII, MD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,WRIGHT STATE UNIV,SD 5,HOUSTON,TX 77058, USA. NR 79 TC 9 Z9 13 U1 1 U2 4 PU W B SAUNDERS CO PI PHILADELPHIA PA INDEPENDENCE SQUARE WEST CURTIS CENTER, STE 300, PHILADELPHIA, PA 19106-3399 SN 0733-8619 J9 NEUROL CLIN JI Neurol. Clin. PD NOV PY 1992 VL 10 IS 4 BP 999 EP 1013 PG 15 WC Clinical Neurology; Neurosciences SC Neurosciences & Neurology GA JW158 UT WOS:A1992JW15800012 PM 1435667 ER PT J AU MEINEL, AB MEINEL, MP AF MEINEL, AB MEINEL, MP TI 2-STAGE OPTICS - HIGH-ACUITY PERFORMANCE FROM LOW-ACUITY OPTICAL-SYSTEMS SO OPTICAL ENGINEERING LA English DT Article DE WAVE-FRONT CORRECTION; ADAPTIVE OPTICS; LARGE TELESCOPES AB We developed the concept of two-stage optics in 1984 under the Jet Propulsion Laboratory's 20-m Large Deployable Telescope (LDR) program to enhance the performance, lower the cost, and increase the reliability of LDR. It permitted the large primary mirror to remain as deployed or as space-assembled, with phasing and subsequent control of the system done by a small, fully assembled optical active element placed at an exit pupil. The performance and tolerances of such a system were explored. A two-stage optics testbed was constructed that successfully demonstrated the concept. Extension of the concept for upgrading the performance of other large, low-cost, wide-field, space optical systems was explored. An opportunity to utilize this concept arose when the problems with the Hubble Space Telescope (HST) were discovered. Its advantages for use in future very large space telescopes are addressed. RP MEINEL, AB (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 10 Z9 10 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 NOV PY 1992 VL 31 IS 11 BP 2271 EP 2281 DI 10.1117/12.59946 PG 11 WC Optics SC Optics GA JY024 UT WOS:A1992JY02400001 ER PT J AU DHAWAN, AP DISIMILE, PJ PECK, C AF DHAWAN, AP DISIMILE, PJ PECK, C TI 3-DIMENSIONAL TEMPORAL RECONSTRUCTION AND ANALYSIS OF PLUME IMAGES SO OPTICAL ENGINEERING LA English DT Article DE FLOW VISUALIZATION; TEMPORAL RECONSTRUCTION; TWIN-JETS IN CROSS-FLOW; PLUME IMAGE ANALYSIS AB There have been a number of methods investigated and under current investigation for monitoring the health of the Space Shuttle Main Engine (SSME). Plume emission analysis has recently emerged as a potential technique for correlating the emission characteristics with the health of an engine. To correlate the visual and spectral signatures of the plume emission with the characteristic health monitoring features of the engine, one has to acquire, store, and analyze the plume emission data in a manner similar to flame emission spectroscopy. The characteristic visual and spectral signatures of the elements vaporized in exhaust plume along with the features related to their temperature, pressure, and velocity can be analyzed once the images of plume emission are effectively acquired, digitized, and stored on a computer. Since the emission image varies with respect to location (the distance from the nozzle) and also with respect to time at a specified planar location, four-dimensional visual and spectral analysis needs to be performed on the plume emission data. To achieve this objective, we conducted feasibility research to digitize, store, analyze, and visualize the images of a subsonic jet in a cross flow. The jet structure was made visible using a direct injection flow visualization technique. The results of temporal (time-history-based) three-dimensional reconstruction of the cross-sectional images corresponding to a specific planar location of the jet structure are presented and the experimental setup to acquire such data is described. 3-D displays of temporal reconstructions of the jet structure are discussed. C1 UNIV CINCINNATI,NASA,CTR SPACE ENGN,DEPT AEROSP ENGN,CINCINNATI,OH 45221. RP DHAWAN, AP (reprint author), UNIV CINCINNATI,NASA,CTR SPACE ENGN,DEPT ELECT & COMP ENGN,CINCINNATI,OH 45221, USA. NR 11 TC 0 Z9 0 U1 1 U2 2 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 NOV PY 1992 VL 31 IS 11 BP 2366 EP 2373 DI 10.1117/12.59893 PG 8 WC Optics SC Optics GA JY024 UT WOS:A1992JY02400012 ER PT J AU Asrar, G Tilford, SG Butler, DM AF Asrar, Ghassem Tilford, Shelby G. Butler, Dixon M. TI Mission to planet Earth: Earth observing system SO PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY LA English DT Article AB Earth Observing System (EOS) is one of the components of the Mission to Planet Earth (MTPE) concept for an international Earth science program to provide the observations, understanding and modeling capabilities needed to assess the impact of natural events and human induced activities on the Earth's environment. MTPE is envisioned to have both the space-based and ground-based observational capabilities, along with the necessary data and information system(s) to accommodate the acquisition, archive and distribution of the data and information acquired about the Earth system. The knowledge gained through this multidisciplinary and international scientific partnership will help increase our understanding of the functioning of the Earth as a coupled system, a prerequisite to informed management of the planet's resources and to the preservation of the global environment. C1 NASA, Off Space Sci & Applicat, Earth Sci & Appl Div, Washington, DC 20546 USA. RP Asrar, G (reprint author), NASA, Off Space Sci & Applicat, Earth Sci & Appl Div, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0031-0182 J9 PALAEOGEOGR PALAEOCL JI Paleogeogr. Paleoclimatol. Paleoecol. PD NOV PY 1992 VL 98 IS 1 BP 3 EP 8 DI 10.1016/0031-0182(92)90251-Y PG 6 WC Geography, Physical; Geosciences, Multidisciplinary; Paleontology SC Physical Geography; Geology; Paleontology GA V43VX UT WOS:000202963700002 ER PT J AU Schoeberl, M Pfaendtner, J Rood, R Thompson, A Wielicki, B AF Schoeberl, Mark Pfaendtner, James Rood, Richard Thompson, Anne Wielicki, Bruce TI Atmospheres Panel report to the payload Panel SO PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY LA English DT Article C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Langley Res Ctr, Hampton, VA USA. RP Schoeberl, M (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 0 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0031-0182 J9 PALAEOGEOGR PALAEOCL JI Paleogeogr. Paleoclimatol. Paleoecol. PD NOV PY 1992 VL 98 IS 1 BP 9 EP 23 DI 10.1016/0031-0182(92)90252-Z PG 15 WC Geography, Physical; Geosciences, Multidisciplinary; Paleontology SC Physical Geography; Geology; Paleontology GA V43VX UT WOS:000202963700003 ER PT J AU HIROI, T TAKEDA, H AF HIROI, T TAKEDA, H TI CRYSTAL-FIELD THEORY CALCULATIONS FOR FE2+ IONS IN BRONZITE, AUGITE, AND OLIVINE SO PHYSICS AND CHEMISTRY OF MINERALS LA English DT Article ID POLARIZED SPECTRA; IRON; SILICATES; ORTHOPYROXENE AB Crystal-field theory was applied to Fe2+ ions in three types of silicates in an attempt to assign all the major absorption bands with only one parameter to adjust. Coulomb potential energy field were calculated by Fourier method based on all the actual atomic coordinates refined by X-ray diffraction studies. Perturbed d-electron splitting energies of the central Fe2+ ion were calculated by introducing Configuration Interaction (CI) method for the lowest energy spectral states. All the major absorption bands observed in powdered bronzite, augite, and olivine, were assigned to the transitions between those calculated energy levels by optimizing only one parameter that expresses expansion or contraction of d-electron cloud. The result of the calculations gives almost the same assignments as the other previous works for bronzites, different assignments for augites, and a possibility of the existence of the fourth band hidden in the composite 1-mum band of olivines. C1 UNIV TOKYO,FAC SCI,INST MINERAL,BUNKYO KU,TOKYO 113,JAPAN. RP HIROI, T (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN3,HOUSTON,TX 77058, USA. NR 24 TC 5 Z9 5 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0342-1791 J9 PHYS CHEM MINER JI Phys. Chem. Miner. PD NOV PY 1992 VL 19 IS 4 BP 229 EP 235 PG 7 WC Materials Science, Multidisciplinary; Mineralogy SC Materials Science; Mineralogy GA JW516 UT WOS:A1992JW51600004 ER PT J AU CHOUDHARI, M STREETT, CL AF CHOUDHARI, M STREETT, CL TI A FINITE REYNOLDS-NUMBER APPROACH FOR THE PREDICTION OF BOUNDARY-LAYER RECEPTIVITY IN LOCALIZED REGIONS SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID TOLLMIEN-SCHLICHTING WAVES; FREE-STREAM DISTURBANCES; SURFACE GEOMETRY; STABILITY; GENERATION AB Earlier theoretical work on the boundary-layer receptivity problem utilized the triple-deck framework, and typically produced only the leading-order asymptotic result. The applicability of these predictions was limited to the generation of Tollmien-Schlichting-type (viscosity-conditioned) instabilities and rather high values of an appropriate Reynolds number. Generalizing the concepts behind the asymptotic theory of Goldstein and Ruban, the classical Orr-Sommerfeld theory is utilized to predict the receptivity due to small-amplitude surface nonuniformities. This approach accounts for the finite Reynolds-number effects, and can also be extended easily to problems involving other types of instabilities. It is illustrated here for the case of the Tollmien-Schlichting wave generation in a Blasius boundary layer, due to the interaction of a free-stream acoustic wave with a region of short-scale variation in one of the surface boundary conditions. The type of surface disturbances examined include regions of short-scale variations in wall suction, wall admittance, and wall geometry (roughness). Results from the finite Reynolds-number approach are compared in detail with previous asymptotic predictions, as well as the available experimental data. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP CHOUDHARI, M (reprint author), HIGH TECHNOL CORP,HAMPTON,VA 23666, USA. RI Choudhari, Meelan/F-6080-2017 OI Choudhari, Meelan/0000-0001-9120-7362 NR 46 TC 41 Z9 41 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 NOV PY 1992 VL 4 IS 11 BP 2495 EP 2514 DI 10.1063/1.858437 PG 20 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JV124 UT WOS:A1992JV12400018 ER PT J AU LUNDGREN, PR GIARDINI, D AF LUNDGREN, PR GIARDINI, D TI SEISMICITY, SHEAR FAILURE AND MODES OF DEFORMATION IN DEEP SUBDUCTION ZONES SO PHYSICS OF THE EARTH AND PLANETARY INTERIORS LA English DT Article; Proceedings Paper CT SYMP OF THE INTERNATIONAL ASSOC OF SEISMOLOGY AND PHYSICS OF THE EARTHS INTERIOR - PHYSICAL PROPERTIES OF THE EARTHS INTERIOR : MANTLE TO CORE CY AUG 20-21, 1991 CL VIENNA, AUSTRIA SP INT ASSOC SEISMOL & PHYS EARTHS INTERIOR ID MOMENT TENSOR SOLUTIONS; WAVE TRAVEL TIME; FOCUS EARTHQUAKES; NORTHWEST PACIFIC; GLOBAL SEISMICITY; SLAB PENETRATION; LOWER MANTLE; JULY-SEPTEMBER; ISLAND ARCS; LATERAL STRUCTURE AB Planes of sheaf failure in deep seismic zones are identified as being parallel to focal mechanism nodal planes of deep focus earthquakes. We relocate deep seismicity reported in the International Seismological Centre (ISC) catalogue for earthquakes deeper than 400 km in the Honshu, Bonin, Marianas, Java, Banda, and South America subduction zones using the joint hypocentral determination method. Recent events with Harvard centroid-moment tensor (CMT) solutions and nearby seismicity are viewed from the direction of the CMT null axis, comparing the two orthogonal nodal planes with the seismicity pattern. Planar features of seismicity parallel to CMT nodal planes are found in each deep seismic zone. and are identified as planes of shear failure. The sense of displacement on these planes is one of resistance to deeper penetration. Honshu and Bonin show imbrication and horizontal displacement of the deepest part of the seismogenic slab, while Marianas and Brazil show conjugate shear failure. Banda and Argentina show patterns of vertical and horizontal shear planes. For the Western Pacific slabs we find significant lateral displacements towards the south of the deepest part of the subduction flow. Tonga has been analyzed previously, showing the same pattern as identified here. In all Benioff zones, planes of shear failure are observed which act to shorten the slabs and displace matter horizontally, normal to the slab; moreover, differential faulting acts to rotate the slab of subducted lithosphere to a more horizontal posture, indicating that slabs experience resistance to penetration of the 670 km discontinuity. C1 IST NAZL GEOFIS,I-00161 ROME,ITALY. RP LUNDGREN, PR (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Giardini, Domenico/F-5406-2011 NR 65 TC 34 Z9 34 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0031-9201 J9 PHYS EARTH PLANET IN JI Phys. Earth Planet. Inter. PD NOV PY 1992 VL 74 IS 1-2 BP 63 EP 74 DI 10.1016/0031-9201(92)90068-7 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KA569 UT WOS:A1992KA56900006 ER PT J AU BAKER, DN CHIN, G PFAFF, RF AF BAKER, DN CHIN, G PFAFF, RF TI WHAT ACCELERATES AURORAL PARTICLES - REPLY SO PHYSICS TODAY LA English DT Letter RP BAKER, DN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Chin, Gordon/E-1520-2012 NR 3 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 0031-9228 J9 PHYS TODAY JI Phys. Today PD NOV PY 1992 VL 45 IS 11 BP 118 EP 119 PG 2 WC Physics, Multidisciplinary SC Physics GA JZ321 UT WOS:A1992JZ32100021 ER PT J AU ULABY, FT AF ULABY, FT TI TERAHERTZ TECHNOLOGY SO PROCEEDINGS OF THE IEEE LA English DT Editorial Material RP ULABY, FT (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9219 J9 P IEEE JI Proc. IEEE PD NOV PY 1992 VL 80 IS 11 BP 1661 EP 1661 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA KC434 UT WOS:A1992KC43400001 ER PT J AU WATERS, JW AF WATERS, JW TI SUBMILLIMETER-WAVELENGTH HETERODYNE SPECTROSCOPY AND REMOTE-SENSING OF THE UPPER-ATMOSPHERE SO PROCEEDINGS OF THE IEEE LA English DT Article ID STRATOSPHERIC MEASUREMENTS; OZONE; CHLORINE; DESTRUCTION; MILLIMETER; CHEMISTRY; SINK; CLO AB Submillimeter wavelengths are rich in spectral lines of atmospheric molecules. Remote sensing using heterodyne spectroscopy at these wavelengths can provide measurements for monitoring changes and studying processes in the earth's upper atmosphere. An experiment for this purpose performing measurements in spectral bands near 63, 183, and 205 GHz is now operational on the NASA Upper Atmosphere Research Satellite (UARS). An experiment which includes measurements in spectral bands up to 2.5 THz is currently being studied for future earth observation systems. RP WATERS, JW (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 49 TC 44 Z9 44 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 0018-9219 J9 P IEEE JI Proc. IEEE PD NOV PY 1992 VL 80 IS 11 BP 1679 EP 1701 DI 10.1109/5.175249 PG 23 WC Engineering, Electrical & Electronic SC Engineering GA KC434 UT WOS:A1992KC43400003 ER PT J AU REBEIZ, GM AF REBEIZ, GM TI MILLIMETER-WAVE AND TERAHERTZ INTEGRATED-CIRCUIT ANTENNAS SO PROCEEDINGS OF THE IEEE LA English DT Review ID TAPERED SLOT ANTENNA; CORNER-CUBE ANTENNAS; HORN ANTENNAS; SUBMILLIMETER WAVELENGTH; PLANAR ANTENNAS; FRONT END; MIXER; RECEIVER; ARRAYS; EFFICIENCY AB This paper presents a comprehensive review of integrated circuit antennas suitable for millimeter and terahertz applications. A great deal of research was done on integrated circuit antennas in the last decade and many of the problems associated with electrically thick dielectric substrates, such as substrate modes and poor radiation patterns, have been understood and solved Several new antennas, such as the integrated horn antenna, the dielectric-filled parabola the Fresnel plate antenna, the dual-slot antenna, and the log-periodic and spiral antennas on extended hemispherical lenses, have resulted in excellent performance at millimeter-wave frequencies, and are covered in detail in this paper. Also, a review of the efficiency definitions used with planar antennas is given in detail in the appendix. RP REBEIZ, GM (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 144 TC 184 Z9 185 U1 4 U2 53 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9219 J9 P IEEE JI Proc. IEEE PD NOV PY 1992 VL 80 IS 11 BP 1748 EP 1770 DI 10.1109/5.175253 PG 23 WC Engineering, Electrical & Electronic SC Engineering GA KC434 UT WOS:A1992KC43400007 ER PT J AU CHIN, G AF CHIN, G TI OPTICALLY PUMPED SUBMILLIMETER LASER HETERODYNE RECEIVERS - ASTROPHYSICAL OBSERVATIONS AND RECENT TECHNICAL DEVELOPMENTS SO PROCEEDINGS OF THE IEEE LA English DT Article ID NEUTRAL ATOMIC CARBON; FAR-INFRARED WAVELENGTHS; MOLECULAR CLOUDS; CO LINE; 1ST DETECTION; GAS; EMISSION; ORION; SPECTROSCOPY; REGIONS AB NASA is planning a series of submillimeter space missions beginning with the Small Explorer Submillimeter Wave Astronomy Satellite, due to be launched in 1995, followed by the Submillimeter Intermediate Mission, and eventually culminating in the observatory-class Large Deployable Reflector. During the 1990's, submillimeter observations at both high mountain sites and on the Kuiper Airborne Observatory and its planned replacement, the Stratospheric Observatory for Infrared Astronomy, will play important active roles in submillimeter observations. The technical challenges faced by experimenters in extending terahertz receiver technology for space operations are daunting. A recent NASA study, the Astrotech 21 Workshop, has pointed out the pressing need for suitable local oscillator (LO) sources for future submillimeter space missions. Optically pumped submillimeter lasers currently provide the only proven LO source for heterodyne receivers in the 600-3000 GHz range. Laser heterodyne receiver systems have been productively used for many years for ground-based and airborne observations. The submillimeter laser, the heart of the system, represents the heaviest and largest component of a heterodyne receiver system. These lasers can now be reduced by a factor of 3-5 in size and weight using new technologies such as RF-excited waveguide CO2 laser pumps and novel submillimeter cavity designs. This paper will review both ground-based and airborne astrophysical applications of laser heterodyne receivers and will present recent technical developments which may allow such systems to be utilized for future space missions. RP CHIN, G (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Chin, Gordon/E-1520-2012 NR 68 TC 7 Z9 7 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 0018-9219 J9 P IEEE JI Proc. IEEE PD NOV PY 1992 VL 80 IS 11 BP 1788 EP 1799 DI 10.1109/5.175255 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA KC434 UT WOS:A1992KC43400009 ER PT J AU RAISANEN, AV AF RAISANEN, AV TI FREQUENCY-MULTIPLIERS FOR MILLIMETER AND SUBMILLIMETER WAVELENGTHS SO PROCEEDINGS OF THE IEEE LA English DT Article ID BARRIER MIXER DIODES; WAVE MULTIPLIERS; SCHOTTKY-DIODES; TRIPLER; THZ; MULTIPLICATION; OUTPUT; RANGE; NOISE; GHZ AB All-solid-state local oscillators in the terahertz frequency range are especially needed for space-borne radio astronomy and remote sensing of the atmosphere. Because solid-state oscillators cannot yet produce the necessary local oscillator power at submillimeter wavelengths, frequency multipliers are needed. So far, submillimeter-wave frequency multipliers are mainly based on a whisker-contacted Schottky diode as the nonlinear element. This paper discusses the multiplier theory and tools for analysis and design of millimeter- and submillimeter-wave multipliers. Experimental work is reviewed The Schottky diode model at submillimeter frequencies, use of Schottky multiplier chains versus direct higher-order multipliers, and the effect of cooling on Schottky diode multipliers are discussed. Alternative diodes such as the high electron mobility varactor (HEMV), the barrier-intrinsic-n+ diode (BIN), the barrier-n-n+ diode (BNN), the quantum well diode (QWD), and the single barrier varactor (SBV) are discussed, with attention also given to their potential as submillimeter frequency multipliers. RP RAISANEN, AV (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. RI Raisanen, Antti/G-2405-2013 NR 71 TC 69 Z9 69 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 0018-9219 J9 P IEEE JI Proc. IEEE PD NOV PY 1992 VL 80 IS 11 BP 1842 EP 1852 DI 10.1109/5.175259 PG 11 WC Engineering, Electrical & Electronic SC Engineering GA KC434 UT WOS:A1992KC43400013 ER PT J AU FRERKING, MA EAST, JR AF FRERKING, MA EAST, JR TI NOVEL HETEROJUNCTION VARACTORS SO PROCEEDINGS OF THE IEEE LA English DT Article ID MULTIPLIERS; MILLIMETER AB Varactor multipliers are a critical component of most millimeter- and submillimeter-wave receiver systems. Schottky barrier diodes are typically used but several new structures based on heterostructure layers have been proposed recently. This paper briefly describes several of these newer structures and discusses their potential performance. C1 UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109. RP FRERKING, MA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 14 TC 15 Z9 15 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 0018-9219 J9 P IEEE JI Proc. IEEE PD NOV PY 1992 VL 80 IS 11 BP 1853 EP 1862 DI 10.1109/5.175260 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA KC434 UT WOS:A1992KC43400014 ER PT J AU MCBEATH, MK MORIKAWA, K KAISER, MK AF MCBEATH, MK MORIKAWA, K KAISER, MK TI PERCEPTUAL BIAS FOR FORWARD-FACING MOTION SO PSYCHOLOGICAL SCIENCE LA English DT Article ID APPARENT MOTION; REPRESENTATION; ORIENTATION; MOVEMENT AB When an occluded horizontal row of shapes is shifted laterally, apparent motion can be experienced in either the leftward or the rightward direction. Four experiments provide evidence for a motion bias in the direction that shapes appear to face. The bias tended to be largest when directionality was specified geometrically (e.g., triangles), next largest when it was specified biologically (e.g., mice), and absent when it was specified calligraphically (e.g., letter R). The bias increased parametrically as a function of triangle pointedness and was consistent with the directional interpretation of an ambiguous duck-rabbit. The results support the existence of a cognitively specified forward-facing attribute that can influence experienced direction of motion. C1 STANFORD UNIV,STANFORD,CA 94305. RP MCBEATH, MK (reprint author), NASA,AMES RES CTR,MAIL STOP 262-3,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035, USA. NR 30 TC 42 Z9 43 U1 0 U2 3 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0956-7976 J9 PSYCHOL SCI JI Psychol. Sci. PD NOV PY 1992 VL 3 IS 6 BP 362 EP 367 DI 10.1111/j.1467-9280.1992.tb00048.x PG 6 WC Psychology, Multidisciplinary SC Psychology GA JW801 UT WOS:A1992JW80100010 ER PT J AU HONEYCUTT, RK TURNER, GW VESPER, DN SCHLEGEL, EM AF HONEYCUTT, RK TURNER, GW VESPER, DN SCHLEGEL, EM TI MR-PERSEI - A NEW ROTATING, SPOTTED FLARE STAR SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID NORTHERN DWARF NOVAE; LOW-MASS STARS; TIME-SERIES; VELOCITIES; PLEIADES; CLUSTER AB Spectroscopy and photometry are used to show that MR Persei, an object originally classified as a dwarf nova, is in fact a flare star. The automated CCD photometry consists of sequences of exposures within a single night as well as long-term photometry over a 5-month interval. One sequence shows a 30-min flare, accompanied by post-flare "dips." A 0.2 mag variation with a period of about one-half day is also seen in this sequence. The long-term photometry is used to refine the period to 0.45483 d, which we attribute to the rotation of a spotted star. Evidence for membership of MR Per in the young alpha Per cluster is considered, and found to be inconclusive. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP HONEYCUTT, RK (reprint author), INDIANA UNIV,DEPT ASTRON,BLOOMINGTON,IN 47405, USA. NR 43 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD NOV PY 1992 VL 104 IS 681 BP 1039 EP 1044 DI 10.1086/133087 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JY713 UT WOS:A1992JY71300003 ER PT J AU TRALLI, DM LICHTEN, SM HERRING, TA AF TRALLI, DM LICHTEN, SM HERRING, TA TI COMPARISON OF KALMAN FILTER ESTIMATES OF ZENITH ATMOSPHERIC PATH DELAYS USING THE GLOBAL POSITIONING SYSTEM AND VERY LONG BASE-LINE INTERFEROMETRY SO RADIO SCIENCE LA English DT Article ID PHASE AMBIGUITY RESOLUTION; RADIO INTERFEROMETRY; LINE INTERFEROMETRY; WATER-VAPOR; GEODETIC BASELINES; MODELING ERRORS; GPS ORBIT; CALIFORNIA; MOTIONS; GULF AB Kalman filter estimates of zenith nondispersive atmospheric path delays at Westford, Massachusetts, Fort Davis, Texas, and Mojave, California, were obtained from independent analyses of data collected during January and February 1988 using the Global Positioning System (GPS) and very long baseline interferometry (VLBI). The apparent accuracy of the path delays is inferred by examining the estimates and covariances from both sets of data. The ability of the geodetic data to resolve zenith path delay fluctuations is determined by comparing further the GPS Kalman filter estimates with corresponding wet path delays derived froin water vapor radiometric (WVR) data available at Mojave over two 8-hour data spans within the comparison period. GPS and VLBI zenith path delay estimates agree well within one standard deviation formal uncertainties (from 10-20 mm for GPS and 3-15 mm for VLBI) in four out of the five possible comparisons, with maximum differences of 5 and 21 mm over 8- to 12-hour data spans. For one comparison, the maximum difference between GPS and VLBI is 50 +/- 20 mm and clearly shows an unexplained systematic difference which is probably related to poor elevation angle coverage in the VLBI data at the time, GPS fiducial network sensitivity, and poor azimuthal coverage. The root-mean-square differences between GPS estimates of the total path delays and WVR measurements added to the hydrostatic delay component determined from surface barometric pressure data are between 9 and 15 mm, however, with biases of 10-15 mm. C1 MIT,DEPT EARTH ATMOSPHERIC & PLANETARY SCI,CAMBRIDGE,MA 02139. RP TRALLI, DM (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 37 TC 14 Z9 14 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD NOV-DEC PY 1992 VL 27 IS 6 BP 999 EP 1007 DI 10.1029/92RS01779 PG 9 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA KB002 UT WOS:A1992KB00200022 ER PT J AU KAHLE, AB ALLEY, RE AF KAHLE, AB ALLEY, RE TI SEPARATION OF TEMPERATURE AND EMITTANCE IN REMOTELY SENSED RADIANCE MEASUREMENTS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article AB The remote determination Of surface temperature and surface spectral emittance by use of airborne or satellite-borne thermal infrared instruments is not straightforward. The radiance measured is a function Of surface temperature, the unknown surface spectral emittance, and absorption and emission in the intervening atmosphere. With a single measurement, the solution for temperature and spectral emittance is underdetermined. This article reviews two of the early approximate methods which have been fairly widely used to approach this problem. RP KAHLE, AB (reprint author), JET PROP LAB,MS 183-501,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 TC 54 Z9 57 U1 1 U2 3 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 NOV PY 1992 VL 42 IS 2 BP 107 EP 111 DI 10.1016/0034-4257(92)90093-Y PG 5 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA JU973 UT WOS:A1992JU97300003 ER PT J AU HOOK, SJ GABELL, AR GREEN, AA KEALY, PS AF HOOK, SJ GABELL, AR GREEN, AA KEALY, PS TI A COMPARISON OF TECHNIQUES FOR EXTRACTING EMISSIVITY INFORMATION FROM THERMAL INFRARED DATA FOR GEOLOGIC STUDIES SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID IMAGES; SCANNER AB This article evaluates three techniques developed to extract emissivity information from multispectral thermal infrared data. The techniques are the assumed Channel 6 emittance model, thermal log residuals, and alpha residuals. These techniques were applied to calibrated, atmospherically corrected thermal infrared multispectral scanner (TIMS) data acquired over Cuprite, Nevada in September 1990. Results indicate that the two new techniques (thermal log residuals and alpha residuals) provide two distinct advantages over the assumed Channel 6 emittance model. First, they permit emissivity information to be derived from all six TIMS channels. The assumed Channel 6 emittance model only permits emissivity values to be derived from five of the six TIMS channels. Second, both techniques are less susceptible to noise than the assumed Channel 6 emittance model. The disadvantage of both techniques is that laboratory data must be converted to thermal log residuals or alpha residuals to facilitate comparison with similarly processed image data. An additional advantage of the alpha residual technique is that the processed data are scene-independent unlike those obtained with the other techniques. C1 CSIRO,DIV EXPLORAT GEOSCI,PERTH,WA,AUSTRALIA. CSIRO,DIV EXPLORAT GEOSCI,SYDNEY,NSW,AUSTRALIA. UNIV READING,DEPT METEOROL,READING RG6 2AH,BERKS,ENGLAND. RP HOOK, SJ (reprint author), JET PROP LAB,183-501,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 141 Z9 154 U1 6 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 NOV PY 1992 VL 42 IS 2 BP 123 EP 135 DI 10.1016/0034-4257(92)90096-3 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA JU973 UT WOS:A1992JU97300006 ER PT J AU THOMAS, ASW AF THOMAS, ASW TI CORRECTION-FREE RADIOMETRY ON SPECULAR SPHERES FOR CONTAINERLESS PROCESSING IN MICROGRAVITY SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB An analysis is presented that establishes how correction-free radiance measurements or pyrometry can be performed on targets in furnaces where there may be significant additional radiance from heated furnace walls or from reflecting surfaces close to the target. These configurations are common in microgravity and containerless processing applications where a specular target is radiantly heated in a hot-wall furnace, or inductively heated from the fields arising from nearby closely spaced electromagnetic coils. Proper design requires that the pyrometer does not view any images of the background features in the specular target so that stray radiation will not be reflected into the viewing optics of the pyrometer. To analyze the problem, conventional paraxial optics analysis is shown to be significantly in error. Instead a method of nonparaxial ray tracing, based on the derivatives of the ray paths, shows how the images must be located. This leads to analytical results that can be used to design such systems. The findings are applied to the furnace geometries that are presently being considered for flight in low-earth orbit. However, the same results may be used in other applications where any radiance measurement is being made on a specular target, as is the case for any molten material in a furnace. C1 JET PROP LAB,PASADENA,CA 91109. NR 9 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 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD NOV PY 1992 VL 63 IS 11 BP 5394 EP 5402 DI 10.1063/1.1143408 PG 9 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JW822 UT WOS:A1992JW82200029 ER PT J AU AGGARWAL, MD WANG, WS SHIELDS, AW PENN, BG FRAZIER, DO AF AGGARWAL, MD WANG, WS SHIELDS, AW PENN, BG FRAZIER, DO TI A VERSATILE LOW-COST CZOCHRALSKI CRYSTAL-GROWTH SYSTEM FOR NONLINEAR OPTICAL ORGANIC MATERIALS SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Note AB A versatile low-cost Czochralski system for pulling crystals from melt has been described. It is designed for low melting, transparent, and nonlinear optical materials. One of the most important novel feature of this crystal growth system is that the entire growth process including the solid-liquid interface can be viewed from any direction. Another is the use of an after-heater to reduce excess heat loss from the surface of the melt. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP AGGARWAL, MD (reprint author), ALABAMA A&M UNIV,DEPT PHYS,NORMAL,AL 35762, USA. NR 9 TC 3 Z9 3 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD NOV PY 1992 VL 63 IS 11 BP 5481 EP 5482 DI 10.1063/1.1143373 PG 2 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JW822 UT WOS:A1992JW82200046 ER PT J AU NOEBE, RD LERCH, BA AF NOEBE, RD LERCH, BA TI ROOM-TEMPERATURE CYCLIC DEFORMATION-BEHAVIOR OF CAST AND EXTRUDED NIAL SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID DUCTILITY RP NOEBE, RD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 19 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 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD NOV 1 PY 1992 VL 27 IS 9 BP 1161 EP 1166 DI 10.1016/0956-716X(92)90592-3 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA JT625 UT WOS:A1992JT62500011 ER PT J AU WOLFF, CL AF WOLFF, CL TI INTERMITTENT SOLAR PERIODICITIES SO SOLAR PHYSICS LA English DT Article ID R-MODES; DIAMETER MEASUREMENTS; FLARES; SUN; OSCILLATIONS; EVOLUTION AB The signal from a stable periodicity can seem to be intermittent when it is partially masked by an unmodelled window function or when the data set is too short to resolve closely spaced periodicities. By taking this into account, short-lived periodicities in solar data can be reinterpreted as evidence for continuously periodic behavior. The periodic sources are located in the solar interior and caused by global oscillation modes. The convective envelope acts as the window for these sources. Recent reports of seven periodicities from 100 to 1000 days are compared with this model. Precise long-term values for the periodicities are predicted and they agree closely with observations. Some elements are suggested that might explain the well-documented 155-day periodicity. Conventional filtering methods to suppress effects of the 11-year cycle are criticized as inadequate. RP WOLFF, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 35 TC 35 Z9 40 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD NOV PY 1992 VL 142 IS 1 BP 187 EP 195 DI 10.1007/BF00156641 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX667 UT WOS:A1992JX66700013 ER PT J AU EILER, JH NELSON, BD BRADSHAW, RF AF EILER, JH NELSON, BD BRADSHAW, RF TI RIVERINE SPAWNING BY SOCKEYE-SALMON IN THE TAKU RIVER, ALASKA AND BRITISH-COLUMBIA SO TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY LA English DT Article ID ONCORHYNCHUS-NERKA; EMERGENCE; HABITAT; SIZE AB Radio telemetry was used to determine the distribution of sockeye salmon Oncorhynchus nerka returning to spawn in the glacial Taku River in 1984 and 1986, and to locate and characterize spawning areas used by this species. During the study, 253 sockeye salmon were tracked as they moved upriver; 204 of these were followed to spawning areas. Only 37% of the 204 fish traveled to areas associated with lakes, the remaining 63% returned to ''riverine'' areas-river areas without lakes (42% to the Taku River main stem, 17% to the Nakina River, and 4% to other rivers). Sockeye salmon spawning in riverine areas used a variety of habitat types, including main-river channels, side channels, tributary streams, and upland sloughs. Most (55%) of the radio-tagged fish that returned to the Taku River main stem were tracked to side-channel spawning areas. Half of the 471 adult sockeye salmon sampled in main-stem spawning areas had migrated to sea as juveniles before their first winter. This study showed that many sockeye salmon returning to the Taku River do not depend on lakes, and that riverine sockeye salmon make up a major portion of the run in some river systems. RP EILER, JH (reprint author), NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,AUKE BAY LAB,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 31 TC 30 Z9 30 U1 0 U2 3 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 SN 0002-8487 J9 T AM FISH SOC JI Trans. Am. Fish. Soc. PD NOV PY 1992 VL 121 IS 6 BP 701 EP 708 DI 10.1577/1548-8659(1992)121<0701:RSBSSI>2.3.CO;2 PG 8 WC Fisheries SC Fisheries GA KR622 UT WOS:A1992KR62200001 ER PT J AU PHELAN, BA AF PHELAN, BA TI WINTER FLOUNDER MOVEMENTS IN THE INNER NEW-YORK BIGHT SO TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY LA English DT Article ID PSEUDOPLEURONECTES-AMERICANUS AB Winter flounder Pleuronectes americanus collected in the inner New York Bight were tagged and released to determine generalized movement patterns. Between July 1986 and August 1989, there were 7,346 winter flounder (greater-than-or-equal-to 18 cm) tagged at 14 inshore stations in Sandy Hook, Raritan, and Lower bays and the Shrewsbury River and at 22 offshore stations associated with a sewage sludge dumpsite 22 km off the New Jersey coast. Results from 206 tag returns indicated that the Navesink-Shrewsbury river system, part of the Sandy Hook-Raritan estuary, supports a population of winter flounder that returns yearly during the spawning season. Winter flounder exhibited limited seasonal migration and intermixed with other winter flounder from the inner New York Bight, indicating the existence of a dynamic assemblage. RP PHELAN, BA (reprint author), NATL MARINE FISHERIES SERV,NE FISHERIES CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 22 TC 34 Z9 35 U1 0 U2 2 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 SN 0002-8487 J9 T AM FISH SOC JI Trans. Am. Fish. Soc. PD NOV PY 1992 VL 121 IS 6 BP 777 EP 784 DI 10.1577/1548-8659(1992)121<0777:WFMITI>2.3.CO;2 PG 8 WC Fisheries SC Fisheries GA KR622 UT WOS:A1992KR62200009 ER PT J AU WING, BL GUTHRIE, CM GHARRETT, AJ AF WING, BL GUTHRIE, CM GHARRETT, AJ TI ATLANTIC SALMON IN MARINE WATERS OF SOUTHEASTERN ALASKA SO TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY LA English DT Note ID GYRODACTYLUS-SALARIS; NORWEGIAN RIVERS; POPULATIONS; HYBRIDS; GROWTH AB An immature female Atlantic salmon Salmo salar, caught by a commercial salmon troller off southeastern Alaska on 20 July 1990, is the first documented representative of this species in the marine waters of Alaska. Identification was based on morphology, meristic characters, and protein electrophoresis. Scale growth patterns, an eroded or clipped dorsal fin, and a high proportion of regenerated scales indicate that the fish escaped from an aquaculture pen during spring 1990. Five additional Atlantic salmon were subsequently caught by commercial fishermen in southeastern Alaska during August 1991; identification was based on morphology and color patterns. Escaped Atlantic salmon are unlikely to have a genetic impact on native Pacific salmonids, but the possibility exists that they will disseminate non-endemic pathogens or parasites. C1 UNIV ALASKA FAIRBANKS, SCH FISHERIES & OCEAN SCI, JUNEAU CTR FISHERIES & OCEAN SCI, JUNEAU, AK 99801 USA. RP WING, BL (reprint author), NATL MARINE FISHERIES SERV, ALASKA FISHERIES SCI CTR, AUKE BAY LAB, 11305 GLACIER HIGHWAY, JUNEAU, AK 99801 USA. NR 29 TC 10 Z9 10 U1 0 U2 4 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 530 WALNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA SN 0002-8487 EI 1548-8659 J9 T AM FISH SOC JI Trans. Am. Fish. Soc. PD NOV PY 1992 VL 121 IS 6 BP 814 EP 818 DI 10.1577/1548-8659(1992)121<0814:ASIMWO>2.3.CO;2 PG 5 WC Fisheries SC Fisheries GA KR622 UT WOS:A1992KR62200015 ER PT J AU HEEGER, DJ AF HEEGER, DJ TI HALF-SQUARING IN RESPONSES OF CAT STRIATE CELLS SO VISUAL NEUROSCIENCE LA English DT Review DE STRIATE (PRIMARY VISUAL) CORTEX; SIMPLE CELLS; COMPLEX CELLS; SPATIOTEMPORAL LINEAR OPERATORS; ENERGY MECHANISMS; SQUARING; DIRECTION SELECTIVITY ID SIMPLE RECEPTIVE-FIELDS; LATERAL GENICULATE-NUCLEUS; TEMPORAL-FREQUENCY-SELECTIVITY; VISUAL CORTICAL-NEURONS; ADJACENT SIMPLE CELLS; WHITE-NOISE-ANALYSIS; SPATIAL-FREQUENCY; COMPLEX CELLS; DIRECTIONAL SELECTIVITY; CONTRAST SENSITIVITY AB Simple cells in striate cortex have been depicted as rectified linear operators, and complex cells have been depicted as energy mechanisms (constructed from the squared sums of linear operator outputs). This paper discusses two essential hypotheses of the linear/energy model: (1) that a cell's selectivity is due to an underlying (spatiotemporal and binocular) linear stage; and (2) that a cell's firing rate depends on the squared output of the underlying linear stage. This paper reviews physiological measurements of cat striate cell responses, and concludes that both of these hypotheses are supported by the data. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HEEGER, DJ (reprint author), STANFORD UNIV,DEPT PSYCHOL,STANFORD,CA 94305, USA. NR 105 TC 181 Z9 181 U1 1 U2 4 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 NOV PY 1992 VL 9 IS 5 BP 427 EP 443 PG 17 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA JU214 UT WOS:A1992JU21400001 PM 1450099 ER PT J AU YANG, SL CHEN, R CLINE, MC NGUYEN, HL MICKLOW, GJ AF YANG, SL CHEN, R CLINE, MC NGUYEN, HL MICKLOW, GJ TI NUMERICAL-SIMULATION OF A LOW-EMISSION GAS-TURBINE COMBUSTOR USING KIVA-II SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE GAS TURBINE COMBUSTORS; CFD; EMISSIONS; AIRBLAST ATOMIZERS; DILUTION JET MIXING ID SPEEDS AB A numerical study was performed to investigate chemically reactive flows with sprays inside a staged turbine combustor (STC) using a modified version of the KIVA-II code. This STC consists of a fuel nozzle (FN), a rich-burn (RB) zone, a converging connecting pipe, a quick-quench (QQ) zone, a diverging connecting pipe and a lean-combustion (LC) zone. From the computational viewpoint, it is more efficient to split the STC into two subsystems, called FN/RB zone and QQ/LC zones, and the numerical solutions were obtained separately for each subsystem. This paper addresses the numerical results of the STC which is equipped with an advanced airblast fuel nozzle. The airblast nozzle has two fuel injection passages and four air flow passages. The input conditions used in this study were chosen similar to those encountered in advanced combustion systems. Preliminary results generated illustrate some of the major features of the flow and temperature fields inside the STC. Velocity, temperature and some critical species information inside the FN/RB zone are given. Formation of the co- and counter-rotating bulk flow and the sandwiched-ring-shaped temperature field, typical of the confined inclined jet-in-cross-flow, can be seen clearly in the QQ/LC zones. The calculations of the mass-weighted standard deviation and the pattern factor of temperature revealed that the mixing performance of the STC is very promising. The temperature of the fluid leaving the LC zone is very uniform. Prediction of the NOx emission shows that there is no excessive thermal NOx produced in the QQ/LC zones for the case studied. From the results obtained so far, it appears that the modified KIVA-II code can be used to guide the low-emission combustion experiments. C1 LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87544. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. UNIV FLORIDA,GAINESVILLE,FL 32611. RP YANG, SL (reprint author), MICHIGAN TECHNOL UNIV,ME-EM DEPT,1400 TOWNSEND DR,HOUGHTON,MI 49931, USA. NR 19 TC 5 Z9 5 U1 1 U2 4 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 OCT 30 PY 1992 VL 15 IS 8 BP 865 EP 881 DI 10.1002/fld.1650150803 PG 17 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA JU725 UT WOS:A1992JU72500002 ER PT J AU HARRISS, RC WOFSY, SC BARTLETT, DS SHIPHAM, MC JACOB, DJ HOELL, JM BENDURA, RJ DREWRY, JW MCNEAL, RJ NAVARRO, RL GIDGE, RN RABINE, VE AF HARRISS, RC WOFSY, SC BARTLETT, DS SHIPHAM, MC JACOB, DJ HOELL, JM BENDURA, RJ DREWRY, JW MCNEAL, RJ NAVARRO, RL GIDGE, RN RABINE, VE TI THE ARCTIC BOUNDARY-LAYER EXPEDITION (ABLE-3A) - JULY AUGUST 1988 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC METHANE; AIR CHEMISTRY; ICE-CORE; TROPOSPHERE; TUNDRA; STRATOSPHERE; POLLUTION; AEROSOLS; CLIMATE; ALASKA AB The Arctic Boundary Layer Expedition (ABLE 3A) used measurements from ground, aircraft, and satellite platforms to characterize the chemistry and dynamics of the lower atmosphere over Arctic and sub-Arctic regions of North America during July and August 1988. The primary objectives of ABLE 3A were to investigate the magnitude and variability of methane emissions from the tundra ecosystem, and to elucidate factors controlling ozone production and destruction in the Arctic atmosphere. This paper reports the experimental design for ABLE 3A and a summary of results. Methane emissions from the tundra landscape varied widely from -2.1 to 426 mg CH4 m-2 d-1. Soil moisture and temperature were positively correlated with methane emission rates, indicating quantitative linkages between seasonal climate variability and soil metabolism, Enclosure flux measurement techniques, tower-based eddy correlation, and airborne eddy correlation flux measurements all proved robust for application to methane studies in the tundra ecosystem. Measurements and photochemical modeling of factors involved in ozone production and destruction validated the hypothesized importance of low NO(x) concentrations as a dominant factor in maintaining the pristine Arctic troposphere as an ozone sink. Stratospheric intrusions, long-range transport of mid-latitude pollution, forest fires, lightning, and aircraft are all potential sources of NO(x) and NO(y) to Arctic and sub-Arctic regions. ABLE 3A results indicate that human activities may have already enhanced NO(y) inputs to the region to the extent that the lifetime of O3 against photochemical loss may have already doubled. A doubling of NO(x) concentration from present levels would lead to net photochemical production of O3 during summer months in the Arctic (Jacob et al., this issue (a)). The ABLE 3A results indicate that atmospheric chemical changes in the northern high latitudes may serve as unique early warning indicators of the rates and magnitude of global environmental change. C1 NASA,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA. HARVARD UNIV,CAMBRIDGE,MA 02138. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. NASA,DIV EARTH SCI & APPLICAT,WASHINGTON,DC 20546. RP HARRISS, RC (reprint author), UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824, USA. NR 52 TC 59 Z9 59 U1 1 U2 11 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 OCT 30 PY 1992 VL 97 IS D15 BP 16383 EP 16394 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000001 ER PT J AU SHIPHAM, MC BACHMEIER, AS CAHOON, DR BROWELL, EV AF SHIPHAM, MC BACHMEIER, AS CAHOON, DR BROWELL, EV TI METEOROLOGICAL OVERVIEW OF THE ARCTIC BOUNDARY-LAYER EXPEDITION (ABLE-3A) FLIGHT SERIES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SAMPLING PROGRAM AGASP; ATMOSPHERIC TRANSPORT; AEROSOL; TRAJECTORIES; CLIMATOLOGY; HAZE; GAS AB A meteorological overview of the Arctic Boundary Layer Expedition (ABLE 3A) flight series is presented. Synoptic analyses of mid-tropospheric circulation patterns are combined with isentropic back trajectory calculations to describe the long-range (400-3000 km) atmospheric transport mechanisms and pathways of air masses to the Arctic and sub-Arctic regions of North America during July and August 1988. Siberia and the northern Pacific Ocean were found to be the two most likely source areas for 3-day transport to the study areas in Alaska. Transport to the Barrow region was frequently influenced by polar vortices and associated short-wave troughs over the Arctic Ocean, while the Bethel area was most often affected by lows migrating across the Bering Sea and the Gulf of Alaska, as well as ridges of high pressure which built into interior Alaska. July 1988 was warmer and dryer than normal over much of Alaska. As a result, the 1988 Alaska fire season was one of the most active of the past decade. Airborne lidar measurements verified the presence of biomass burning plumes on many flights, often trapped in thin subsidence layer temperature inversions. Several cases of stratosphere/troposphere exchange were noted, based upon potential vorticity analyses and aircraft lidar data, especially in the Barrow region and during transit flights to and from Alaska. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA. RP SHIPHAM, MC (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 26 TC 30 Z9 30 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-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 30 PY 1992 VL 97 IS D15 BP 16395 EP 16419 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000002 ER PT J AU JACOB, DJ WOFSY, SC BAKWIN, PS FAN, SM HARRISS, RC TALBOT, RW BRADSHAW, JD SANDHOLM, ST SINGH, HB BROWELL, EV GREGORY, GL SACHSE, GW SHIPHAM, MC BLAKE, DR FITZJARRALD, DR AF JACOB, DJ WOFSY, SC BAKWIN, PS FAN, SM HARRISS, RC TALBOT, RW BRADSHAW, JD SANDHOLM, ST SINGH, HB BROWELL, EV GREGORY, GL SACHSE, GW SHIPHAM, MC BLAKE, DR FITZJARRALD, DR TI SUMMERTIME PHOTOCHEMISTRY OF THE TROPOSPHERE AT HIGH NORTHERN LATITUDES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PEROXYACETYL NITRATE; OZONE DISTRIBUTIONS; ABSORPTION-SPECTRUM; BOREAL FOREST; ACETIC-ACIDS; EMISSIONS; STRATOSPHERE; AMAZONIA; NITROGEN; KINETICS AB The budgets of O3, NO(x) (NO+NO2), reactive nitrogen (NO(y)), and acetic acid in the 0-6 km column over western Alaska in summer are examined by photochemical modeling of aircraft and ground-based measurements from the Arctic Boundary Layer Expedition (ABLE 3A). It is found that concentrations of O3 in the region are regulated mainly by input from the stratosphere, and losses of comparable magnitude from photochemistry and deposition. The concentrations of NO(x) (10-50 ppt) are sufficiently high to slow down O3 photochemical loss appreciably relative to a NO(x)-free atmosphere; if no NO(x) were present, the lifetime of O3 in the 0-6 km column would decrease from 46 to 26 days because of faster photochemical loss. The small amounts of NO(x) present in the Arctic troposphere have thus a major impact on the regional O3 budget. Decomposition of peroxyacetyl nitrate (PAN) can account for most of the NO(x) below 4-km altitude, but for only 20% at 6-km altitude. Decomposition of other organic nitrates might supply the missing source of NO(x). The lifetime of NO(y) in the ABLE 3A flight region is estimated at 29 days, implying that organic nitrate precursors of NO(x) could be supplied from distant sources including fossil fuel combustion at northern mid-latitudes. Biomass fire plumes sampled during ABLE 3A were only marginally enriched in O3; this observation is attributed in part to low NO(x) emissions in the fires, and in part to rapid conversion of NO(x) to PAN promoted by low atmospheric temperatures. It appears that fires make little contribution to the regional O3 budget. Only 30% of the acetic acid concentrations measured during ABLE 3A can be accounted for by reactions of CH3CO3 with HO2 and CH3O2. There remains a major unidentified source of acetic acid in the atmosphere. C1 UNIV CALIF IRVINE,IRVINE,CA 92717. ATMOSPHER SCI RES CTR,ALBANY,NY. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. UNIV NEW HAMPSHIRE,DURHAM,NH 03824. GEORGIA INST TECHNOL,ATLANTA,GA 30332. RP JACOB, DJ (reprint author), HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138, USA. NR 48 TC 106 Z9 107 U1 1 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 OCT 30 PY 1992 VL 97 IS D15 BP 16421 EP 16431 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000003 ER PT J AU BROWELL, EV BUTLER, CF KOOI, SA FENN, MA HARRISS, RC GREGORY, GL AF BROWELL, EV BUTLER, CF KOOI, SA FENN, MA HARRISS, RC GREGORY, GL TI LARGE-SCALE VARIABILITY OF OZONE AND AEROSOLS IN THE SUMMERTIME ARCTIC AND SUB-ARCTIC TROPOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC OZONE; TROPOPAUSE FOLD; INSITU MEASUREMENTS; AMAZON BASIN; LAYER OZONE; MARCH 1983; AIR; DISTRIBUTIONS; INTRUSIONS; CHEMISTRY AB Measurements of ozone (O3) and aerosol distributions were made with an airborne lidar system in the Arctic and sub-Arctic during July-August 1988 as part of the NASA Global Tropospheric Experiment/Arctic Boundary Layer Expedition (ABLE 3A). Aerosol and O3 profiles were measured simultaneously above and below the Electra aircraft from near the surface to above the tropopause. In situ measurements of O3 mixing ratios and aerosol size distributions and number densities were also made on the aircraft. Many different atmospheric conditions were investigated on long-range survey flights in the Arctic and on intensive flights over the tundra, ice, and marine regions near Barrow and Bethel, Alaska. The tropospheric composition at high latitudes was found to be strongly influenced by stratospheric intrusions. Regions of low-aerosol scattering and enhanced O3 mixing ratios were correlated with descending air from the lower stratosphere. Over 37% of the troposphere along our flight track at latitudes >57-degrees-N had significantly enhanced O3 levels due to stratospheric intrusions, and in the 4- to 6-km altitude range the tropospheric extent of the enhanced O3 exceeded 56%. Ozone mixing ratios of 80 ppbv at 6 km were common, with vertical O3 gradients of over 11 ppbv km-1 observed across the base of strong intrusions. In the mixed layer over the tundra, O3 was in the 25-35 ppbv range with a gradient of 5.5 ppbv km-1, while in continental polar air masses, the average gradient in the lower troposphere was 7.4 ppbv km 1, indicating more downward transport of O3 at higher latitudes. Due to the many forest fires that year, plumes from biomass burning sources were observed on several flights over Alaska. Plumes influenced about 10% of the air below 4 km, and in some photochemically active plumes, O3 was enhanced by 10-20 ppbv over ambient levels. Pollution plumes from industrial sources were infrequently observed; however, a few large plumes were found over the North Pacific with greatly enhanced aerosol scattering and with O3 levels exceeding 75 ppbv. C1 S T SYST CORP,HAMPTON,VA. UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824. RP BROWELL, EV (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 55 TC 46 Z9 46 U1 0 U2 8 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 OCT 30 PY 1992 VL 97 IS D15 BP 16433 EP 16450 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000004 ER PT J AU GREGORY, GL ANDERSON, BE WARREN, LS BROWELL, EV BAGWELL, DR HUDGINS, CH AF GREGORY, GL ANDERSON, BE WARREN, LS BROWELL, EV BAGWELL, DR HUDGINS, CH TI TROPOSPHERIC OZONE AND AEROSOL OBSERVATIONS - THE ALASKAN ARCTIC SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RESPONSE CHARACTERISTICS; TROPOPAUSE FOLDS; STRATOSPHERE; TRANSPORT; COUNTERS; SYSTEMS; ORIGIN; AIR AB NASA's Arctic Boundary Layer Expedition (ABLE 3A) conducted during the summer of 1988 focused on the distribution of trace species in the Alaskan Arctic troposphere (altitudes <7 km) and the relative importance of surface sources/sinks, local emissions, distant transport, and tropospheric/stratospheric exchange. In situ ozone and aerosol number density and size data obtained during aircraft flights from Point Barrow and Bethel, Alaska, are discussed. Data are also presented for the ferry flights between Wallops Island, Virginia, and Point Barrow, Alaska, via Thule, Greenland. The major source of summer ozone for the troposphere is the intrusion of stratospheric air and subsequent transport to the lower altitudes. Photochemistry of mixed layer emissions and ozone transported from high northern latitude urban/industrialized areas do not appear to play major roles as sources of ozone for the Alaska region. Ozone gradients reflect the loss at the surface and supply from the stratosphere. Free-tropospheric ozone (3- to 7-km altitude) averaged 74 ppbv compared to 32 ppbv for the mixed layer. All four mixed layers studied (water, wet tundra, dry tundra, and boreal forest) are net ozone sinks. Ozone loss mechanisms are a combination of the destruction via photochemistry, chemical reactions with surface emissions, and direct loss through deposition to the surface. The boreal forest is the most efficient of the ozone sinks. Aerosol data showed that, of the mixed layers studied, the boreal forest has the largest increase in aerosol number density relative to the free troposphere. With the exception of the boreal forest, a significant portion of mixed layer aerosols are from the free troposphere. Results also show that while, in theory, free-tropospheric air can be classified as originating from continental or maritime regions (Siberia, Canada, Pacific Ocean, Gulf of Alaska), little difference was found in the ozone and fine aerosol number density composition of the air. This is attributed, in part, to modification of the air during transport from its source region. C1 NASA,LANGLEY RES CTR,DIV OPERAT SUPPORT,HAMPTON,VA 23665. RP GREGORY, GL (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 37 TC 38 Z9 39 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-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 30 PY 1992 VL 97 IS D15 BP 16451 EP 16471 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000005 ER PT J AU JACOB, DJ FAN, SM WOFSY, SC SPIRO, PA BAKWIN, PS RITTER, JA BROWELL, EV GREGORY, GL FITZJARRALD, DR MOORE, KE AF JACOB, DJ FAN, SM WOFSY, SC SPIRO, PA BAKWIN, PS RITTER, JA BROWELL, EV GREGORY, GL FITZJARRALD, DR MOORE, KE TI DEPOSITION OF OZONE TO TUNDRA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DRY DEPOSITION; BOUNDARY-LAYER; VEGETATION; CLIMATE; TERRAIN; MODELS AB Vertical turbulent fluxes of O3 were measured by eddy correlation from a 12-m high tower erected over mixed tundra terrain (dry upland tundra, wet meadow tundra, and small lakes) in western Alaska during the Arctic Boundary Layer Expedition (ABLE 3A). The measurements were made continuously for 30 days in July-August 1988. The mean O3 deposition flux was 1.3 x 10(11) molecules cm-2 s-1. The mean O3 deposition velocity was 0.24 cm s-1 in the daytime and 0.12 cm s-1 at night. The day-to-night difference in deposition velocity was driven by both atmospheric stability and surface reactivity. The mean surface resistance to O3 deposition was 2.6 s cm-1 in the daytime and 3.4 s cm-1 at night. The relatively low surface resistance at night is attributed to light-insensitive uptake of O3 at dry upland tundra surfaces (mosses, lichens). The small day-to-night difference in surface resistance is attributed to additional stomatal uptake by wet meadow tundra plants in the daytime. Flux measurement from the ABLE 3A aircraft flying over the tower are in agreement with the tower data. The mean O3 deposition flux to the world north of 60-degrees-N in July-August is estimated at 8.2 x 10(10) molecules cm-2 s-1, comparable in magnitude to the O3 photochemical loss rate in the region derived from the ABLE 3A aircraft data. Suppression of photochemical loss by small anthropogenic inputs of nitrogen oxides could have a major effect on O3 concentrations in the summertime Arctic troposphere. C1 HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. SUNY ALBANY,ATMOSPHER SCI RES CTR,ALBANY,NY 12222. RP JACOB, DJ (reprint author), HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138, USA. NR 34 TC 39 Z9 39 U1 1 U2 12 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 OCT 30 PY 1992 VL 97 IS D15 BP 16473 EP 16479 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000006 ER PT J AU SANDHOLM, ST BRADSHAW, JD CHEN, G SINGH, HB TALBOT, RW GREGORY, GL BLAKE, DR SACHSE, GW BROWELL, EV BARRICK, JDW SHIPHAM, MA BACHMEIER, AS OWEN, D AF SANDHOLM, ST BRADSHAW, JD CHEN, G SINGH, HB TALBOT, RW GREGORY, GL BLAKE, DR SACHSE, GW BROWELL, EV BARRICK, JDW SHIPHAM, MA BACHMEIER, AS OWEN, D TI SUMMERTIME TROPOSPHERIC OBSERVATIONS RELATED TO NXOY DISTRIBUTIONS AND PARTITIONING OVER ALASKA - ARCTIC BOUNDARY-LAYER EXPEDITION 3A SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NITRIC-OXIDE MEASUREMENTS; ODD-NITROGEN; OZONE PRODUCTION; UNITED-STATES; PEROXYACETYL NITRATE; REACTIVE NITROGEN; CARBON-MONOXIDE; EASTERN PACIFIC; TROPOPAUSE FOLD; STRATOSPHERE AB Measurements of the reactive odd nitrogen compounds NO. NO2, peroxyacetyl nitrate (PAN), and NO(y) are presented for the summertime middle/lower troposphere (6.1-0.15 km) over northern high latitudes. In addition, the chemical signatures revealed from concurrent measurements of O3, CO, C2H2, C2H6, C3H8, C2Cl4, and H2O are used to further characterize factors affecting the budget and distribution of N(x)O(y) in the Arctic and sub-Arctic tropospheric air masses sampled over Alaska during the NASA Arctic Boundary Layer Expedition (ABLE 3A) field campaign. Many of the compounds listed above exhibited a general trend of median mixing ratios increasing in proportion with altitude within the lower 6-km column. However, median mixing ratios of NO and NO(x) (NO + NO2) were nearly independent of altitude, having values of about 8.5 and 25 pptv, respectively. Median mixing ratios of NO(y) varied from about 350 pptv within the lowest altitudes to about 600 pptv within the highest altitudes sampled. PAN constituted the largest fraction of NO(y) (approximately 50%) at the highest altitudes. In addition, PAN mixing ratios accounted for all of the approximate 60 pptv/km altitudinal dependency in NO(y). The analyses presented implicate biomass burning in Siberia as the probable source of about one-third of the NO(y) abundance within the middle/lower troposphere over Alaska. These analyses also implicate the downward transport of air from attitudes in the vicinity of the tropopause as a major contributor to the abundance of NO(y) (approximately 30-50%) within the lower 6-km column over Alaska. However, the exact origin of this high-altitude NO(y) remains uncertain. The impact of lower latitude industrial/urban pollution also remains largely uncertain, although various chemical signatures imply inputs from these regions would have been relatively well aged (15-30 days). C1 PLANNING RES CORP,HAMPTON,VA. S T SYST CORP,HAMPTON,VA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. UNIV CALIF IRVINE,DEPT CHEM,IRVINE,CA 92717. RP SANDHOLM, ST (reprint author), GEORGIA INST TECHNOL,SCH EARTH & ATMOSPHER SCI,ATLANTA,GA 30332, USA. NR 77 TC 68 Z9 68 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-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 30 PY 1992 VL 97 IS D15 BP 16481 EP 16509 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000007 ER PT J AU SINGH, HB OHARA, D HERLTH, D BRADSHAW, JD SANDHOLM, ST GREGORY, GL SACHSE, GW BLAKE, DR CRUTZEN, PJ KANAKIDOU, MA AF SINGH, HB OHARA, D HERLTH, D BRADSHAW, JD SANDHOLM, ST GREGORY, GL SACHSE, GW BLAKE, DR CRUTZEN, PJ KANAKIDOU, MA TI ATMOSPHERIC MEASUREMENTS OF PEROXYACETYL NITRATE AND OTHER ORGANIC NITRATES AT HIGH-LATITUDES - POSSIBLE SOURCES AND SINKS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID REACTIVE NITROGEN; TROPOSPHERIC CHEMISTRY; UNPOLLUTED ATMOSPHERE; ARCTIC STRATOSPHERE; GAS; PAN; HYDROCARBONS; OXIDATION; AEROSOL; OXIDES AB Aircraft measurements of peroxyacetyl nitrate (PAN) and other important reactive nitrogen species (NO, NO2, HNO3, peroxypropionyl nitrate (PPN), CH3ONO2, NO(y)) were performed at high latitudes over North America and Greenland during July-August 1988, at all altitudes between 0 and 6 km as part of an Arctic Boundary Layer Expedition (ABLE 3A). Complementing these were measurements of C1 to C5 hydrocarbons, O3, chemical tracers (C2Cl4, CO), and important meteorological parameters. PAN was found to be an important reactive nitrogen species in the free troposphere, with 95% of the mixing ratios falling in the range of 5 to 450 ppt. PAN increased systematically with height with mixing ratios of 100-700 ppt at 6 km and 0-50 ppt in the boundary layer. The free tropospheric PAN reservoir was present over the entire high-latitude region sampled (50-degrees to 82-degrees-N latitude and 60-degrees to 160-degrees-W longitude). In the boundary layer, PAN mixing ratios were higher over land than over the North Pacific Ocean. Significant levels of PAN were measured within stratospheric intrusions, forest fire plumes, and episodes of remote pollution. Other organic nitrates such as PPN and CH3ONO2 were found to be a small fraction of PAN (0-10%). PAN and O3 were strongly correlated both in their fine and gross structures, and the latitudinal distribution of PAN in the free troposphere followed that of O3. A two dimensional global photochemical model is used to compare measurements and model results. Model simulations, correlations between reactive nitrogen species (e.g. PAN and NO(y)) and anthropogenic tracers (C2H2, CO, C2Cl4 and the composition of NO(y) itself support the view that the reactive nitrogen measured during ABLE 3A is predominantly of anthropogenic origin with a minor stratospheric component. Transported industrial pollution, biomass burning, and the unique seasonal dynamics of the Arctic/sub-Arctic region play a dominant role in defining this reactive nitrogen abundance. This PAN (and NO(y)) reservoir may contribute to the summertime maximum in deposited nitrate observed over Greenland. C1 SAN JOSE STATE UNIV FDN,MOFFETT FIELD,CA. UNIV CALIF IRVINE,IRVINE,CA 92717. GEORGIA INST TECHNOL,ATLANTA,GA 30332. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. MAX PLANCK INST CHEM,W-6500 MAINZ,GERMANY. RP SINGH, HB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Kanakidou, Maria/D-7882-2012; Crutzen, Paul/F-6044-2012 OI Kanakidou, Maria/0000-0002-1724-9692; NR 45 TC 78 Z9 79 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 30 PY 1992 VL 97 IS D15 BP 16511 EP 16522 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000008 ER PT J AU SINGH, HB HERLTH, D OHARA, D ZAHNLE, K BRADSHAW, JD SANDHOLM, ST TALBOT, R CRUTZEN, PJ KANAKIDOU, M AF SINGH, HB HERLTH, D OHARA, D ZAHNLE, K BRADSHAW, JD SANDHOLM, ST TALBOT, R CRUTZEN, PJ KANAKIDOU, M TI RELATIONSHIP OF PEROXYACETYL NITRATE TO ACTIVE AND TOTAL ODD NITROGEN AT NORTHERN HIGH-LATITUDES - INFLUENCE OF RESERVOIR SPECIES ON NOX AND O3 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID REACTIVE NITROGEN; ORGANIC NITRATES; TROPOSPHERE; STRATOSPHERE; CHEMISTRY; OXIDES; PAN; AEROSOL; OZONE; O-3 AB Measurements of peroxyacetyl nitrate (PAN), NO, NO2, HNO3, NO(y) (total odd nitrogen), and O3 were made in the high-latitude troposphere over North America and Greenland (35-degrees to 82-degrees-N) during the Arctic Boundary Layer Expedition (ABLE 3A) (July-August 1988) throughout 0-to 6-km altitudes. These data are analyzed to quantitatively describe the relationships between various odd nitrogen species and assess their significance to global tropospheric chemistry. In the free troposphere, PAN was as much as 25 times more abundant than NO(x). PAN to NO(x) ratio increased with increasing altitude and latitude. PAN was found to be the single most abundant reactive nitrogen species in the free troposphere and constituted a major fraction of Noy, PAN to NO(y), ratios were about 0.1 in the boundary layer and increased to 0.4 in the free troposphere. A 2-D global photochemical model with C1 -C3 hydrocarbon chemistry is used to compare model predictions with measured results. A sizable portion (approximately 50%) of the gaseous reactive nitrogen budget is unaccounted for, and unknown organic nitrates and pernitrates are expected to be present. Model calculations (August 1, 70-degrees-N) show that a major fraction of the observed NO(x) (50 to 70% of median) may find its source in the available PAN reservoir. PAN and the unknown reservoir species may have the potential to control virtually the entire NO(x) availability of the high latitude troposphere. It is predicted that the summer NO(x) and O3 mixing ratios in the Arctic/sub-Arctic troposphere would be considerably lower in the absence of the ubiquitous PAN reservoir. Conversely, this PAN reservoir may be responsible for the observed temporal increase in tropospheric O3 at high latitudes. C1 SAN JOSE STATE FDN,MOFFETT FIELD,CA. UNIV NEW HAMPSHIRE,DURHAM,NH 03824. GEORGIA INST TECHNOL,ATLANTA,GA 30332. MAX PLANCK INST CHEM,W-6500 MAINZ,GERMANY. RP SINGH, HB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Kanakidou, Maria/D-7882-2012; Crutzen, Paul/F-6044-2012 OI Kanakidou, Maria/0000-0002-1724-9692; NR 32 TC 49 Z9 52 U1 1 U2 7 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 OCT 30 PY 1992 VL 97 IS D15 BP 16523 EP 16530 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000009 PM 11538395 ER PT J AU HARRISS, RC SACHSE, GW HILL, GF WADE, L BARTLETT, KB COLLINS, JE STEELE, LP NOVELLI, PC AF HARRISS, RC SACHSE, GW HILL, GF WADE, L BARTLETT, KB COLLINS, JE STEELE, LP NOVELLI, PC TI CARBON-MONOXIDE AND METHANE IN THE NORTH-AMERICAN ARCTIC AND SUB-ARCTIC TROPOSPHERE - JULY AUGUST 1988 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TRACE GASES; HAZE; DISTRIBUTIONS; DIOXIDE AB Measurements of carbon monoxide (CO) and methane (CH4) were made in the North American Arctic during July-August 1988. The distribution of CH4 was variable in the atmospheric mixed layer (0-2 km), with concentrations determined primarily by interactions of biogenic emissions from wet tundra and turbulent mixing processes. Carbon monoxide exhibited little variation in unpolluted mixed layer environments indicating a minor role for biogenic sources and/or sinks in determining its distribution. In the free troposphere (2-6 km) both CO and CH4 were variable. Concentration gradients were most frequently associated with intrusions of upper tropospheric or stratospheric air into the midtroposphere, emissions from forest and tundra fires, and long-range transport of enhanced concentrations of these gases from unidentified sources. Summertime haze layers exhibited midtropospheric enhancements of CH4 similar to those measured in winter Arctic haze events. However, these summer pollution episodes did not exhibit positive correlations with particulate sulfate. The summer Arctic and subarctic haze events observed during the Arctic Boundary Layer Expedition (ABLE 3) were primarily a result of forest and tundra fires of natural origin. The tendency for relatively high variability of CO and CH4 at altitudes of 3-6 km indicates that ground-based monitoring will not provide an adequate assessment of the chemical composition of the Arctic troposphere to support future global change studies. C1 LOCKHEED ENGN & SCI,HAMPTON,VA. SCI & TECHNOL CORP,HAMPTON,VA. UNIV COLORADO,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HARRISS, RC (reprint author), UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824, USA. RI Steele, Paul/B-3185-2009 OI Steele, Paul/0000-0002-8234-3730 NR 33 TC 35 Z9 36 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 30 PY 1992 VL 97 IS D15 BP 16589 EP 16599 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000013 ER PT J AU RITTER, JA BARRICK, JDW SACHSE, GW GREGORY, GL WOERNER, MA WATSON, CE HILL, GF COLLINS, JE AF RITTER, JA BARRICK, JDW SACHSE, GW GREGORY, GL WOERNER, MA WATSON, CE HILL, GF COLLINS, JE TI AIRBORNE FLUX MEASUREMENTS OF TRACE SPECIES IN AN ARCTIC BOUNDARY-LAYER SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CARBON-MONOXIDE; ATMOSPHERIC METHANE; OZONE; CHEMISTRY; TRANSPORT; INCREASE; DYNAMICS; CLIMATE; FOREST; BUDGET AB In situ airborne measurements of the turbulent flux and mean values for O3, CO, and CH4 were obtained in the boundary layer over selected wetland systems in Alaska. These measurements were obtained in July-August 1988 as part of the NASA Global Tropospheric Experiment Program's Arctic Boundary Layer Expedition (ABLE 3A). The flux measurements obtained from this study provide information on the source/sink distribution of O3 and CH4 over the Yukon-Kuskokwim Delta (YKD) and Alaskan North Slope (ANS) regions of Alaska. The source/sink distribution over the YKD is qualitatively correlated with surface vegetation type, identified from multispectral scanner imagery. Direct measurements of the spatial variation in the CH4 source strength were obtained over the YKD. The CH4 source strength over the YKD ranged from 25 to 85 mg m-2 d-1 during a flux survey flight which spanned a considerable portion of the YKD. A spatially averaged, seasonally adjusted source strength of 51 mg m-2 d-1 was established for the YKD. Indirect CH4 flux estimates obtained over the ANS indicate a much lower (approximately 10 mg m-2 d-1) source strength. The global CH4 emissions from tundra were estimated to be 44 Tg/a based on (1) the spatially averaged source strength obtained over the YKD, (2) current estimates of the global coverage of tundra, and (3) assuming a similarity between other tundra areas and that of the YKD. This estimate is taken to be an upper limit due to possible sampling inadequacies and because the spatial distribution of the CH4 source function over the YKD may not extend to all other northern wetland regions. This estimate is. however, in reasonable agreement with previous estimates. Airborne CO flux measurements over the YKD indicated low negative flux values over the coastal areas, while some positive fluxes were observed in the inland, sparsely forested regions. An inspection of the cospectrum of CO with vertical velocity for sample runs in coastal areas indicated a minimum at wavelengths which were noticeably shorter (70-400 m) than where any prominent feature could be found for similar cospectrums of heat, moisture, O3, or CH4 with vertical velocity. Similar analyses for transects over inland areas indicated occasional peaks in this same, short wavelength band. These features indicate the possibility of in situ photochemical destruction/production of CO, although the identification of a possible chemical mechanism was not attempted at this time. Tundra surfaces are estimated to be responsible for approximately 32% of the total deposition loss of O3 poleward of 60-degrees-N. Data from the airborne O3 flux measurements made during this study indicate similar values of R(c) for the ANS and YKD regions. C1 NASA,LANGLEY RES CTR,DIV FLIGHT ELECTR,HAMPTON,VA 23665. SCI & TECHNOL CORP,HAMPTON,VA. RP RITTER, JA (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 64 TC 36 Z9 36 U1 1 U2 10 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 OCT 30 PY 1992 VL 97 IS D15 BP 16601 EP 16625 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000014 ER PT J AU MORRISSEY, LA LIVINGSTON, GP AF MORRISSEY, LA LIVINGSTON, GP TI METHANE EMISSIONS FROM ALASKA ARCTIC TUNDRA - AN ASSESSMENT OF LOCAL SPATIAL VARIABILITY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC METHANE; RICE PADDIES; GLOBAL DISTRIBUTION; SEASONAL CYCLES; TEMPERATURE; WETLANDS; INCREASE; CH4 AB Methane flux was measured in situ in the Alaska Arctic tundra to assess the magnitude and controls on spatial variability of emissions. A total of 122 measurements were made at 57 spatially independent sites across the Alaska North Slope during the summer of 1987. Variability in rates of emissions was similar in magnitude on local and regional scales, ranging from 0 to 286.5 mg CH4 m-2 d-1 overall and often varying across two orders of magnitude within 0.5-m distances. Primary control on rates of emissions was determined by the substrate and the position of the water table relative to the surface. Secondary controls were defined by the substrate temperature and the type and quantity of vegetation participating in the plant-mediated release of CH4 to the atmosphere. Emission rates in the Arctic Foothills ranged from 0.2 mg CH4 m-2 d-1 for tussock tundra to 55.3 mg CH4 m-2 d-1 over wet meadows. Within the Arctic Coastal Plain, rates of emissions were highest on inundated terrestrial sites (72.2 mg CH4 m-2 d-1), decreasing nearly 12 fold on comparable sites where the water table was 5 cm or more below the surface (6.1 mg CH4 m-2 d-1). Emission rates increased linearly with substrate temperatures at 10-cm depth, increasing nearly ninefold over the 6-degrees-C temperature range observed. Plant mediated release of CH4 to the atmosphere was directly proportional to green leaf area and represented 92-98% of the total emission rates over vegetated sites. Comparisons between boreal studies reflect similarities in environmental controls on emissions at local-to-regional scales and demonstrate the sensitivity of regional to global estimates to sampling bias. These results suggest that current published emissions rates may have overestimated the contribution of boreal ecosystems to the global CH4 budget by several fold. RP MORRISSEY, LA (reprint author), NASA,AMES RES CTR,DIV EARTH SYST SCI,TGS TECHNOL INC,MOFFETT FIELD,CA 94035, USA. NR 46 TC 126 Z9 144 U1 2 U2 21 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 OCT 30 PY 1992 VL 97 IS D15 BP 16661 EP 16670 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000017 ER PT J AU WHITING, GJ BARTLETT, DS FAN, SM BAKWIN, PS WOFSY, SC AF WHITING, GJ BARTLETT, DS FAN, SM BAKWIN, PS WOFSY, SC TI BIOSPHERE ATMOSPHERE CO2 EXCHANGE IN TUNDRA ECOSYSTEMS - COMMUNITY CHARACTERISTICS AND RELATIONSHIPS WITH MULTISPECTRAL SURFACE REFLECTANCE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CANOPY REFLECTANCE; VEGETATION INDEX; PHOTOSYNTHESIS; TRANSPIRATION; ALASKA AB The spatial and temporal patterns of many of the factors controlling CO2 exchange are related to characteristics of the vegetated surface which can potentially be monitored using multispectral remote sensors. Realization of this potential depends, in part, on an improved understanding of ecosystem processes and their relationship to variables which are accessible to remote sensing techniques. We examined these relationships using portable, climate-controlled, instrumented enclosures to measure CO2 exchange rates in selected tundra sites near Bethel, Alaska. Rates were related to vegetation community type and climatic variables. Exchange rates in enclosures were compared to exchange measurements obtained by eddy correlation on a 12-m micrometeorological tower. For an average light input of 37 einsteins/day during 20 midsummer days, the empirically modeled exchange rate for a representative area of vegetated tundra was 1.2 +/- 1.1 (95% confidence interval) g CO2 m-2 d-1. This was comparable to a tower measured exchange over the same time period of 1.1 +/- 1.1 (95% confidence interval) g CO2 m-2 d-1. Net exchange in response to varying light levels was compared for two major community types, wet meadow and dry upland tundra, and to the net exchange measured by the micrometeorological tower technique. Portable radiometers were used to measure the multispectral reflectance properties of the sites. These properties were then related to exchange rates with the goal of providing a quantitative foundation for the use of satellite remote sensing to monitor biosphere/atmosphere CO2 exchange in the tundra biome. The Normalized Difference Vegetation Index (NDVI) and the near-infrared/red reflectance ratio (SR) computed from surface reflectance were strongly correlated with net CO2 exchange for both upland and wet meadow vegetation. However, the form of the relationship was distinct from measured correlations in other ecosystems, suggesting that global surveys may require adjustment for geographical differences in exchange processes. C1 UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824. HARVARD UNIV,CTR EARTH & PLANETARY PHYS,CAMBRIDGE,MA 02138. RP WHITING, GJ (reprint author), NASA,LANGLEY RES CTR,HUGHES STX CORP,HAMPTON,VA 23665, USA. NR 28 TC 64 Z9 65 U1 0 U2 8 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 OCT 30 PY 1992 VL 97 IS D15 BP 16671 EP 16680 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000018 ER PT J AU DIBB, JE TALBOT, RW GREGORY, GL AF DIBB, JE TALBOT, RW GREGORY, GL TI BERYLLIUM-7 AND PB-210 IN THE WESTERN-HEMISPHERE ARCTIC ATMOSPHERE - OBSERVATIONS FROM 3 RECENT AIRCRAFT-BASED SAMPLING PROGRAMS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC OZONE; AIR-POLLUTION; ICE-CORE; AEROSOL; TROPOSPHERE; SULFATE; TRANSPORT; ORIGIN; RADON; AGASP AB Concentrations of the natural radionuclides Be-7 and Pb-210 were determined in aerosol samples collected in the western hemisphere Arctic during the recent NOAA Arctic Gas and Aerosol Sampling Program (AGASP 3) and NASA Global Tropospheric Experiment/Arctic Boundary Layer Expeditions (GTE/ABLE 3A and ABLE 3B) missions. Beryllium 7 showed a free tropospheric concentration maximum between 4 and 5 km in the summer of 1990. Previous Be-7 data obtained in the late 1950s and early 1960s also indicated a similar vertical distribution of Be-7 near 70-degrees-N. Injection of stratospheric air through tropopause folds associated with the Arctic jet near 70-degrees-N appears to explain the presence of a layer of air near 4-5 km in the high Arctic free troposphere with elevated Be-7 concentrations. The vertical distribution of Pb-210 showed a distinct difference between the high-Arctic and sub-Arctic in the summer of 1988. At latitudes greater than 65-degrees-N Pb-210 concentrations at 3-6 km were elevated compared to those below 1 km. The reverse of this trend was observed near 60-degrees-N. These same vertical distributions were also apparent in aerosol SO42-, determined in separate aerosol samples collected on the same flights (Talbot et al., this issue). The results for Pb-210 suggest that some of the difference between the summer troposphere in the high- and sub-Arctic is also due to enhanced stratosphere-troposphere exchange in the vicinity of the Arctic jet. These observations, and other findings from ABLE 3A presented in this issue, suggest that for some species the stratosphere may be a principal source influencing their distribution in the Arctic summer troposphere. For example, intrusions of stratospheric air constitute the dominant source term for tropospheric budgets of Be-7 and ozone, and may be important in the Pb-210, SO42-, and NO(y) budgets. Further investigation, including determination of detailed Be-7 and Pb-210 distributions, is needed to quantify the stratospheric impact on the chemistry of the Arctic troposphere during the summer. C1 UNIV NEW HAMPSHIRE, INST STUDY EARTH OCEANS & SPACE, GLOBAL ATMOSPHER CHEM GRP, DURHAM, NH 03824 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. RP DIBB, JE (reprint author), UNIV NEW HAMPSHIRE, INST STUDY EARTH OCEANS & SPACE, GLACIER RES GRP, DURHAM, NH 03824 USA. NR 48 TC 36 Z9 38 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 30 PY 1992 VL 97 IS D15 BP 16709 EP 16715 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000022 ER PT J AU WOFSY, SC SACHSE, GW GREGORY, GL BLAKE, DR BRADSHAW, JD SANDHOLM, ST SINGH, HB BARRICK, JA HARRISS, RC TALBOT, RW SHIPHAM, MA BROWELL, EV JACOB, DJ LOGAN, JA AF WOFSY, SC SACHSE, GW GREGORY, GL BLAKE, DR BRADSHAW, JD SANDHOLM, ST SINGH, HB BARRICK, JA HARRISS, RC TALBOT, RW SHIPHAM, MA BROWELL, EV JACOB, DJ LOGAN, JA TI ATMOSPHERIC CHEMISTRY IN THE ARCTIC AND SUB-ARCTIC - INFLUENCE OF NATURAL FIRES, INDUSTRIAL EMISSIONS, AND STRATOSPHERIC INPUTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID REACTIVE ODD NITROGEN; TRACE GAS EMISSIONS; CARBON-MONOXIDE; GTE CITE-1; PHOTOCHEMICAL PRODUCTION; TROPOSPHERIC OZONE; VERTICAL PROFILES; NORTH PACIFIC; BOREAL FOREST; EASTERN AB Haze layers with perturbed concentrations of trace gases, believed to originate from tundra and forest wild fires, were observed over extensive areas of Alaska and Canada in 1988. Enhancements of CH4, C2H2, C2H6, C3H8, and C4H10 were linearly correlated with CO in haze layers, with mean ratios (mole hydrocarbon/mole CO) of 0.18 (+/- 0.04 (1 sigma)), 0.0019 (+/- 0.0001), 0.0055 (+/- 0.0002), 0.0008 (+/- 0.0001), and 1.2 x10(-4) (+/-0.2x10(-4)), respectively. Enhancements of NO(y) were variable, averaging 0.0056 (+/- 0.0030) mole NO(y)/mole CO, while perturbations of NO(x) were very small, usually undetectable. At least 1/3 of the NO(y) in the haze layers had been converted to peroxyacetyl nitrate (PAN), representing a potential source of NO(x) to the global atmosphere; much of the balance was oxidized to nitrate (HNO3 and particulate). The composition of sub-Arctic haze layers was consistent with aged emissions from smoldering combustion, except for CH4, which appears to be partly biogenic. Inputs from the stratosphere and from biomass fires contributed major fractions of the NO(y) in the remote sub-Arctic troposphere. Analysis of aircraft and ground data indicates relatively little influence from mid-latitude industrial NO(y) in this region during summer, possibly excepting transport of PAN. Production of O3 was inefficient in sub-Arctic haze layers, less than 0.1 O3 molecules per molecule of CO, reflecting the low NO(x)/CO emission ratios from smoldering combustion. Mid-latitude pollution produced much more O3, 0.3-0.5 O3 molecules per molecule of CO, a consequence of higher NO(x)/CO emission ratios. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. GEORGIA INST TECHNOL,SCH EARTH & ATMOSPHER SCI,ATLANTA,GA 30332. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. UNIV CALIF IRVINE,DEPT CHEM,IRVINE,CA 92717. RP WOFSY, SC (reprint author), HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138, USA. NR 48 TC 87 Z9 88 U1 0 U2 16 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 OCT 30 PY 1992 VL 97 IS D15 BP 16731 EP 16746 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JW720 UT WOS:A1992JW72000024 ER PT J AU CHEN, JS KOLAWA, E GARLAND, CM NICOLET, MA RUIZ, RP AF CHEN, JS KOLAWA, E GARLAND, CM NICOLET, MA RUIZ, RP TI MICROSTRUCTURE OF POLYCRYSTALLINE CUINSE2/CD(ZN)S HETEROJUNCTION SOLAR-CELLS SO THIN SOLID FILMS LA English DT Article ID THIN-FILMS; CUINSE2; PERFORMANCE; DEPOSITION; CULNSE2 AB Polycrystalline CuInSe2/Cd(Zn)S heterojunction solar cells deposited on Coming 7059 or soda-lime glass are characterized structurally and chemically by scanning electron microscopy and transmission electron microscopy in conjunction with energy-dispersive analysis of X-rays. Scanning electron micrographs reveal rough and uneven surfaces and cross-sectional morphologies of the Cd(Zn)S and CuInSe2 layers. The crystallography and defect structure of the individual Cd(Zn)S, CuInSe2 and molybdenum layers are examined by conventional and high resolution transmission electron microscopy. The crystal structures for Cd(Zn)S, CuInSe2 and molybdenum are wurtzite, chalcopyrite and b.c.c. respectively. The Cd(Zn)S layer exhibits stacking faults on hexagonal basal planes. Planar defects such as twins and stacking faults on {112}chalcopyrite planes are identified in the CuInSe2 layer. The most significant features obtained from these cross-sections are (i) the lateral non-uniformity of the Cd(Zn)S and CuInSe2 layers, (ii) the intimate bonding between these two layers, and an epitaxial relationship between grains of Cd(Zn)S and CuInSe2 at the interface ({0001}Cd(Zn)S\\{112}CuInSe2), and (iii) the presence of voids and fractures in the CuInSe2 layer. A correlation between the formation of fractures and voids and the defect structure in CuInSe2 layer, and the mechanical stresses induced by differential thermal contraction of the substrate/film assembly is discussed. C1 JET PROP LAB,PASADENA,CA 91109. RP CHEN, JS (reprint author), CALTECH,PASADENA,CA 91125, USA. RI Chen, Jen-Sue/A-3298-2015 NR 28 TC 21 Z9 22 U1 0 U2 6 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0040-6090 J9 THIN SOLID FILMS JI Thin Solid Films PD OCT 30 PY 1992 VL 219 IS 1-2 BP 183 EP 192 DI 10.1016/0040-6090(92)90741-S PG 10 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA JZ124 UT WOS:A1992JZ12400027 ER PT J AU PARTRIDGE, H BAUSCHLICHER, CW AF PARTRIDGE, H BAUSCHLICHER, CW TI CALCULATION OF MG+-LIGAND RELATIVE BINDING-ENERGIES SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; GAS-PHASE; ROW ATOMS; CONTRACTION; IONS AB The calculated relative binding energies of 16 organic molecules to Mg+ are compared with experimental results where available. The geometries of the ligands and the Mg+-ligand complexes are optimized at the self-consistent field (SCF) level using a 6-31G* basis set. The Mg+ binding energies are evaluated using second-order perturbation theory and basis sets of triple-zeta quality augmented with two sets of polarization functions. This level of theory is calibrated against higher levels of theory for selected systems. The computed binding energies are accurate to about 2 kcal/mol. RP PARTRIDGE, H (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 13 TC 19 Z9 19 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD OCT 29 PY 1992 VL 96 IS 22 BP 8827 EP 8832 DI 10.1021/j100201a027 PG 6 WC Chemistry, Physical SC Chemistry GA JW464 UT WOS:A1992JW46400027 ER PT J AU CAHOON, DR STOCKS, BJ LEVINE, JS COFER, WR ONEILL, KP AF CAHOON, DR STOCKS, BJ LEVINE, JS COFER, WR ONEILL, KP TI SEASONAL DISTRIBUTION OF AFRICAN SAVANNA FIRES SO NATURE LA English DT Article AB SAVANNAS consist of a continuous layer of grass interspersed with scattered trees or shrubs, and cover approximately 10 million square kilometres of tropical Africa1,2. African savanna fires, almost all resulting from human activities, may produce as much as a third of the total global emissions from biomass burning3. Little is known, however, about the frequency and location of these fires, and the area burned each year4. Emissions from African savanna burning are known to be transported over the mid-Atlantic, south Pacific and Indian oceans5,6; but to study fully the transport of savanna fire emissions, the spatial and temporal variations in regional savanna burning and the seasonality of the atmospheric circulation must be considered simultaneously. Here we describe the temporal and spatial distribution of savanna fires over the entire African continent, as determined from night-time satellite imagery. We find that, contrary to expectations, most fires are left to burn uncontrolled, so that there is no strong diurnal cycle in the fire frequency. The knowledge gained from this study regarding the distribution and variability of fires will aid monitoring of the climatically important trace gases emitted from burning biomass. C1 FORESTRY CANADA,GREAT LAKES FORESTRY CTR,SAULT ST MARIE P6A 5M7,ONTARIO,CANADA. COLL WILLIAM & MARY,DEPT GEOL,WILLIAMSBURG,VA 23186. RP CAHOON, DR (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 14 TC 178 Z9 181 U1 0 U2 14 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 29 PY 1992 VL 359 IS 6398 BP 812 EP 815 DI 10.1038/359812a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JV777 UT WOS:A1992JV77700058 ER PT J AU PARMAR, DS SINGH, JJ AF PARMAR, DS SINGH, JJ TI PARTIALLY EXPOSED POLYMER DISPERSED LIQUID-CRYSTALS FOR BOUNDARY-LAYER INVESTIGATIONS SO APPLIED PHYSICS LETTERS LA English DT Article AB A new configuration termed partially exposed polymer dispersed liquid crystal in which the liquid crystal microdroplets dispersed in a rigid polymer matrix are partially entrapped on the free surface of the thin film deposited on a glass substrate is reported. Optical transmission characteristics of the partially exposed polymer dispersed liquid crystal thin film in response to an air flow induced shear stress field reveal its potential as a sensor for gas flow and boundary layer investigations. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 18 TC 9 Z9 9 U1 0 U2 3 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 OCT 26 PY 1992 VL 61 IS 17 BP 2039 EP 2041 DI 10.1063/1.108352 PG 3 WC Physics, Applied SC Physics GA JV041 UT WOS:A1992JV04100014 ER PT J AU HORNE, WC SMITH, CA KARAMCHETI, K AF HORNE, WC SMITH, CA KARAMCHETI, K TI DIRECT OBSERVATION OF THE INTERMITTENCY OF INTENSE VORTICITY FILAMENTS IN TURBULENCE - COMMENT SO PHYSICAL REVIEW LETTERS LA English DT Editorial Material C1 FLORIDA STATE UNIV,FLORIDA AGR & MECH UNIV,COLL ENGN,TALLAHASSEE,FL 32316. RP HORNE, WC (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 7 TC 1 Z9 1 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD OCT 26 PY 1992 VL 69 IS 17 BP 2602 EP 2602 DI 10.1103/PhysRevLett.69.2602 PG 1 WC Physics, Multidisciplinary SC Physics GA JV013 UT WOS:A1992JV01300038 ER PT J AU GUEST, JE BULMER, MH AUBELE, J BERATAN, K GREELEY, R HEAD, JW MICHAELS, G WEITZ, C WILES, C AF GUEST, JE BULMER, MH AUBELE, J BERATAN, K GREELEY, R HEAD, JW MICHAELS, G WEITZ, C WILES, C TI SMALL VOLCANIC EDIFICES AND VOLCANISM IN THE PLAINS OF VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MAGELLAN AB The most widespread terrain type on Venus consists of volcanic lowland plains. Several styles of volcanism are represented in the plains. The most extensive volcanic units consist of flood lavas, The largest of which have volumes of the order of thousands of cubic kilometers. As with terrestrial flood lavas, they are inferred to have erupted at high effusion rates. They show a range of radar backscatter characteristics indicating different surface textures and ages. Small edifices on the plains occur mainly in clusters associated with fracture belts. The majority are shield volcanoes that may be up to a few tens of kilometers across but are generally 10 km or less in diameter. Volcanic cones have the same size range. Volcanic domes have diameters up to several tens of kilometers and volumes of the order of 100 km3. These are interpreted as being constructed of lava erupted with a relatively high effective viscosity and thus possibly composed of more silicic lava. For many domes, the flanks were unstable during and afte eruption and suffered gravity sliding that produced steep, scalloped outer margins. Because of the high atmospheric pressures on Venus, explosive activity is less likely to occur than on Earth. However, n a few plains areas there is evidence of pyroclastic deposits surrounding craters, indicating that volatile contents i some of the magmas may be high in comparison to Earth. The clusters of small volcanic edifices are considered to be analogous to plains volcanism, similar to that of the Snake River Plain of Idaho. There may also be analogues with terrestrial volcanic clusters associated with mid-oceanic ridges. C1 BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. JET PROP LAB,PASADENA,CA 91109. ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. RP GUEST, JE (reprint author), UNIV LONDON OBSERV,COLL LONDON,MILL HILL PK,LONDON NW7 2QS,ENGLAND. NR 34 TC 66 Z9 68 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1992 VL 97 IS E10 BP 15949 EP 15966 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JV615 UT WOS:A1992JV61500002 ER PT J AU MCKENZIE, D MCKENZIE, JM SAUNDERS, RS AF MCKENZIE, D MCKENZIE, JM SAUNDERS, RS TI DIKE EMPLACEMENT ON VENUS AND ON EARTH SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID HAWAIIAN VOLCANIC RIFTS; GRAVITATIONAL STRESSES; REGIONAL STRUCTURE; ORIENTATION; FRACTURE; SURFACE; GROWTH AB Many long linear troughs are visible in synthetic aperture radar images of the surface of Venus. Their geometry closely resembles that of dike swarms on Earth. Such troughs will be formed if dikes fail to reach the surface, or if the magma in them is partially drained. Dikes that form closed ellipses in plan view can be produced by intrusions near a depression, and intersecting dikes can result if the stress field changes with time. Because of the absence of erosion and sedimentation, all these effects are better displayed on Venus than they are on Earth. The magnitude of the regional stress on Venus can be estimated from the dike patterns to be about 3 MPa, or similar to that of Earth. Dikes consisting of en echelon segments whose total length is 1500 km or more occur on both Earth and Venus. On Earth their widths are generally greater than 30 m and are sometimes as great as 250 m, and they are likely to be similar on Venus. The melt velocity during their emplacement is predicted to be a few meters per second, and the calculated rate of heat loss is sufficiently slow that they can remain molten as they propagate for distances of more than 1000 km. The same calculations apply to sills, though less is known about their geometry. The results therefore suggest that magma intrusion in thin sheets extending over 1000 km or more could produce regional crustal thickening and uplift on both Earth and Venus. C1 JET PROP LAB,PASADENA,CA 91109. INST THEORET GEOPHYS,DEPT EARTH SCI,CAMBRIDGE,ENGLAND. NR 24 TC 64 Z9 64 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 OCT 25 PY 1992 VL 97 IS E10 BP 15977 EP 15990 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JV615 UT WOS:A1992JV61500004 ER PT J AU JANES, DM SQUYRES, SW BINDSCHADLER, DL BAER, G SCHUBERT, G SHARPTON, VL STOFAN, ER AF JANES, DM SQUYRES, SW BINDSCHADLER, DL BAER, G SCHUBERT, G SHARPTON, VL STOFAN, ER TI GEOPHYSICAL MODELS FOR THE FORMATION AND EVOLUTION OF CORONAE ON VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID TECTONICS; MORPHOLOGY; ORIGIN AB Coronae are large circular features on Venus characterized by an annulus of concentric tectonic features, interior fracturing, volcanism, and generally upraised topography. They are suggested to form over sites of mantle upwelling and modified by subsequent gravitational relaxation. We examine this proposition using two geophysical models to determine whether and under what conditions these mechanisms can produce the topography and tectonics exhibited by coronae in the Magellan altimetry data and radar images. Our results show that mantle diapirism can produce the domical topography of novae, which may be coronae in the earliest stage of formation. The model stresses induced at the surface by a mantle diapir imply the formation of radially oriented extensional fracturing as observed in novae. The dimensions of novae indicate that the diapirs responsible for them are smaller than about 100 km in radius and that the elastic lithosphere is less than 32 km thick. Diapirs that have reached the top of the mantle are expected to spread and flatten, producing plateaulike rather than domical topography. We model a flattened diapir at the top of the mantle and show that it will result in plateaulike uplift. The volume of the flattened model diapir is similar to that of the spherical diapirs derived for novae. We model gravitational relaxation of isostatically uncompensated plateaus and show that they relax to the topographic forms associated with coronae and that the model stresses are consistent with the development of the annulus of tectonic features around coronae. 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 JANES, DM (reprint author), CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853, USA. NR 22 TC 95 Z9 96 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 OCT 25 PY 1992 VL 97 IS E10 BP 16055 EP 16067 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JV615 UT WOS:A1992JV61500008 ER PT J AU BANERDT, WB SAMMIS, CG AF BANERDT, WB SAMMIS, CG TI SMALL-SCALE FRACTURE PATTERNS ON THE VOLCANIC PLAINS OF VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INITIAL ANALYSIS; MAGELLAN; TECTONICS; MODELS; GROWTH; ORIGIN; CRACK AB Some of the most striking features of the Magellan radar images of Venus are the intricate and varied deformation patterns on the volcanic plains. Particularly puzzling are remarkably linear features with a regular spacing of about 1 km first observed in the gridded plains of Guinevere Planitia. The very close spacing of these features requires an unreasonably thin lithospheric layer in conventional geophysical models for regular spacing. We have found many sets of parallel, regularly spaced lineations similar to the closely spaced features of the gridded plains. They are composed of parallel, thin, straight lineations whose microwave reflectivity does not appear to depend on radar illumination direction. These sets of parallel lineations, which we interpret to be fractures, typically cover areas with dimensions of hundreds of kilometers. Several examples of these regular lineations are characterized in terms of their average fracture spacing, which is between 1 and 2.5 km; the scatter in individual spacings is about +/-1/3 the average. Based on observations, we hypothesize that these features are extension fractures in the brittle upper layers of the volcanic plains material, which formed well after emplacement and solidification of the flows. For parallel extension cracks, models based on the stress distribution around a crack and observations of regular jointing in sedimentary layers predict that the spacing of fractures should be roughly equal to the depth of fracturing, or to the thickness of the jointed layer. However, we observe that fracture sets in diverse locations all have nearly the same spacing, implying either that the fractures always form with a depth extent of about 1 km or that the spacing is independent of the thickness of the layer containing the fractures. We propose a model based on a shear lag mechanism used by materials scientists to explain morphologically similar patterns of regularly spaced tensile cracks on the brittle surfaces of layered composites. In this model, lithospheric extension causes a fracture to form in a surface layer of basalt several hundred meters to a kilometer thick. A horizontal detachment, corresponding to an older plains surface below the fractured layer, allows frictionally resisted lateral displacement of the surface layer in the region near the extension fracture. The model gives a spacing that is independent of layer thickness and is able to reproduce the observed fracture spacing using reasonable values of material constants. It provides a framework for using these sets of lineations to help determine mechanical properties of the volcanic plains and to place constraints on the sequence of their tectonic evolution. Another unresolved problem of the gridded plains has been the presence of an orthogonal set of brighter structures with a markedly different appearance and a somewhat larger scale of spacing. We utilize the observed morphology and self-similarity of feature lengths to determine the reasons for their contrasting morphology. It is concluded that they are primarily extensional structures which penetrate the entire 2-4 km thick brittle crustal layer and which are likely to have accommodated some shear deformation. C1 UNIV SO CALIF,DEPT GEOL SCI,LOS ANGELES,CA 90089. RP BANERDT, WB (reprint author), JET PROP LAB,MS 183-501,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 40 TC 18 Z9 18 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 OCT 25 PY 1992 VL 97 IS E10 BP 16149 EP 16166 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JV615 UT WOS:A1992JV61500012 ER PT J AU PLAUT, JJ ARVIDSON, RE AF PLAUT, JJ ARVIDSON, RE TI COMPARISON OF GOLDSTONE AND MAGELLAN RADAR DATA IN THE EQUATORIAL PLAINS OF VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SURFACE AB Goldstone radar observations of the equatorial plains of Venus provide complementary information to that obtained by Magellan. Different radar scattering mechanisms dominate each system, leading to a sampling of different surface properties. Comparison of image data and derived parameters indicate that (1) relatively high dielectric constants on impact-related parabolic features are detected in Goldstone backscatter, Magellan reflectivity, and Magellan emissivity data; the dielectric effects are overwhelmed by roughness-related signatures in Magellan synthetic aperature radar (SAR) data, (2) lava flows in Navka Planitia show dielectric variations both among and with flows; higher dielectric constants on the perimeter of some flows may be due to a decrease in vesicularity, (3) some volcanic domes are relatively smooth at the wavelength scale and probably consist of low-density deposits, (4) comparisons of Magellan SAR data with rough surface scattering models and SAR data of terrestrial surfaces indicate that the roughness characteristics of the equatorial plains surfaces are comparable to modified terrestrial lava flows, and (5) scattering properties of an equatorial "ridge belt" structure suggest highly weathered or soil-dominated surfaces. C1 WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130. RP PLAUT, JJ (reprint author), JET PROP LAB,MS 230-225,4800 OAK GROVE,PASADENA,CA 91109, USA. NR 20 TC 8 Z9 8 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 OCT 25 PY 1992 VL 97 IS E10 BP 16279 EP 16291 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JV615 UT WOS:A1992JV61500016 ER PT J AU BASILEVSKY, AT NIKOLAEVA, OV WEITZ, CM AF BASILEVSKY, AT NIKOLAEVA, OV WEITZ, CM TI GEOLOGY OF THE VENERA-8 LANDING SITE REGION FROM MAGELLAN DATA - MORPHOLOGICAL AND GEOCHEMICAL CONSIDERATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ALKALINE VOLCANIC-ROCKS; MAGMA GENESIS; CALC-ALKALINE; NEW-MEXICO; VENUS; SURFACE; MANTLE; EVOLUTION; ORIGIN; LAMPROPHYRES AB A photogeologic analysis of high-resolution Magellan radar images covering the Venera 8 landing site area has shown that: (1) the majority of the region is characterized by mottle plain; (2) a younger plains complex exists in the western half of the landing circle; and (3) there are steep-sided domes and a possible collapsed caldera inside the landing circle. A preliminary photogeological analysis of all the geochemically studied Venera/Vega sites has shown that for the Venera 8 and 13 sites, where nontholeiitic compositions were measured for the surface material, steep-sided domes were found. Meanwhile, for the five sites where geochemical signatures of tholeiitic basalts were identified (Venera 9, 10, and 14 and Vega 1 and 2), steep-sided domes were not found. Emissivity, reflectivity, altimetry, and rms slope values inside the landing circle are typical for the Venusian plains. A continuation of searching through the literature for terrestrial igneous rocks with similar K2O, U, and Th contents as the Venera 8 material resulted in the finding of another group of rocks which are K2O-U-Th analogs of the material (in addition to a previously identified group of evolved intermediate subalkaline rocks). These potential analogs are dike rocks (lamprophyres) with mostly mafic silica contents. Among these analogs is a sample having the same K2O and Th content as the Venera 8 material (no uranium content was measured) and a primitive bulk chemistry close to the Venera 13 material. Both evolved and mafic terrestrial igneous rocks identified as analogs or as potential analogs to the Venera 8 material showed a distinct enrichment of their magma and/or magma source in incompatible elements. This indicates the involvement of continental crust material in the terrestrial analogs, and it suggests that crustal material enriched in incompatible elements may also be present on Venus. C1 JET PROP LAB,PASADENA,CA 91109. RP BASILEVSKY, AT (reprint author), VI VERNADSKY GEOCHEM & ANALYT CHEM INST,MOSCOW 117975,USSR. NR 70 TC 28 Z9 28 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-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1992 VL 97 IS E10 BP 16315 EP 16335 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JV615 UT WOS:A1992JV61500018 ER PT J AU BENTLEY, JA BOWMAN, JM GAZDY, B LEE, TJ DATEO, CE AF BENTLEY, JA BOWMAN, JM GAZDY, B LEE, TJ DATEO, CE TI A GLOBAL ABINITIO POTENTIAL FOR HCN/HNC, EXACT VIBRATIONAL ENERGIES, AND COMPARISON TO EXPERIMENT SO CHEMICAL PHYSICS LETTERS LA English DT Article ID FLOPPY TRIATOMIC-MOLECULES; HNC REVERSIBLE HCN; OVERTONE TRANSITIONS; CLASSICAL DYNAMICS; HYDROGEN-CYANIDE; -> HCN; STATES; ISOMERIZATION; SPECTRA; SURFACE AB An ab initio, i.e. from first principles, calculation of vibrational energies of HCN and HNC is reported. The vibrational calculations were done with a new potential derived from a fit to 1124 ab initio electronic energies. which were calculated using the highly accurate CCSD(T) coupled-cluster method in conjunction with a large atomic natural orbital basis set. The properties of this potential are presented, and the vibrational calculations are compared to experiment for 54 vibrational transitions. 39 of which are for zero total angular momentum, J=0, and 15 of which are for J=1. The level of agreement with experiment is unprecedented fora triatomic with two non-hydrogen atoms, and demonstrates the capability of the latest computational methods to give reliable predictions on a strongly bound triatomic molecule at very high levels of vibrational excitation. C1 EMORY UNIV,DEPT CHEM,ATLANTA,GA 30322. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. ELORET INST,PALO ALTO,CA 94303. RI Lee, Timothy/K-2838-2012 NR 59 TC 61 Z9 63 U1 0 U2 9 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 OCT 23 PY 1992 VL 198 IS 6 BP 563 EP 569 DI 10.1016/0009-2614(92)85031-5 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JU851 UT WOS:A1992JU85100005 ER PT J AU RAMPINO, MR CALDEIRA, K AF RAMPINO, MR CALDEIRA, K TI ANTIPODAL HOTSPOT PAIRS ON THE EARTH SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CRETACEOUS TERTIARY BOUNDARY; FLOOD-BASALT VOLCANISM; HOT SPOTS; PLATE; MANTLE; PLUMES AB The results of statistical analyses performed on three published hotspot distributions suggest that significantly more hotspots occur as nearly antipodal pairs than is anticipated from a random distribution, or from their association with geoid highs and divergent plate margins. The observed number of antipodal hotspot pairs depends on the maximum allowable deviation from exact antipodality. At a maximum deviation of less-than-or-equal-to 700 km, 26% to 37% of hotspots form antipodal pairs in the published lists examined here, significantly more than would be expected from the general hotspot distribution. Two possible mechanisms that might create such a distribution include: (1) symmetry in the generation of mantle plumes, and (2) melting related to antipodal focusing of seismic energy from large-body impacts. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. PENN STATE UNIV,CTR EARTH SYST SCI,UNIV PK,PA 16802. PENN STATE UNIV,DEPT GEOSCI,UNIV PK,PA 16802. RP RAMPINO, MR (reprint author), NYU,DEPT APPL SCI,EARTH SYST GRP,NEW YORK,NY 10003, USA. RI Caldeira, Ken/E-7914-2011 NR 35 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 OCT 23 PY 1992 VL 19 IS 20 BP 2011 EP 2014 DI 10.1029/92GL01984 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JW001 UT WOS:A1992JW00100005 ER PT J AU SLADE, MA BUTLER, BJ MUHLEMAN, DO AF SLADE, MA BUTLER, BJ MUHLEMAN, DO TI MERCURY RADAR IMAGING - EVIDENCE FOR POLAR ICE SO SCIENCE LA English DT Article ID COHERENT BACKSCATTER; DETECTING POTASSIUM; ATMOSPHERE; SODIUM; REFLECTIVITY; SATELLITES; ALTIMETRY; MARS AB The first unambiguous full-disk radar mapping of Mercury at 3.5-centimeter wavelength, with the Goldstone 70-meter antenna transmitting and 26 antennas of the Very Large Array receiving, has provided evidence for the presence of polar ice. The radar experiments, conducted on 8 and 23 August 1991, were designed to image the half of Mercury not photographed by Mariner 10. The orbital geometry allowed viewing beyond the north pole of Mercury; a highly reflective region was clearly visible on the north pole during both experiments. This polar region has areas in which the circular polarization ratio (mu(c)) was 1.0 to 1.4; values < approximately 0.1 are typical for terrestrial planets. Such high values of mu(c) have hitherto been observed in radar observations only from icy regions of Mars and icy outer planet satellites. C1 CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP SLADE, MA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 45 TC 158 Z9 159 U1 1 U2 7 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 23 PY 1992 VL 258 IS 5082 BP 635 EP 640 DI 10.1126/science.258.5082.635 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JU745 UT WOS:A1992JU74500053 PM 17748898 ER PT J AU HARMON, JK SLADE, MA AF HARMON, JK SLADE, MA TI RADAR MAPPING OF MERCURY - FULL-DISK IMAGES AND POLAR ANOMALIES SO SCIENCE LA English DT Article AB A random-code technique has been used at Arecibo to obtain delay-Doppler radar images of the full disk of Mercury. Anomalously bright features were found at the north and south poles. The north polar feature is oblong (4-degrees by 8-degrees) and offset from the pole. The smaller south polar feature is mostly confined to the floor of the crater Chao Meng-Fu. The polar locations and radar properties of these features indicate that they may be produced by volume scattering in ice. The images also reveal a variety of more subdued reflectivity features ranging in size from hundreds to thousands of kilometers; some of these appear to have an impact origin. C1 JET PROP LAB,PASADENA,CA 91109. RP HARMON, JK (reprint author), NATL ASTRON & IONOSPHERE CTR,ARECIBO,PR 00613, USA. NR 17 TC 113 Z9 113 U1 0 U2 7 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 23 PY 1992 VL 258 IS 5082 BP 640 EP 643 DI 10.1126/science.258.5082.640 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JU745 UT WOS:A1992JU74500054 PM 17748899 ER PT J AU SHIRINZADEH, B HILLARD, ME BALLA, RJ WAITZ, IA ANDERS, JB EXTON, RJ AF SHIRINZADEH, B HILLARD, ME BALLA, RJ WAITZ, IA ANDERS, JB EXTON, RJ TI PLANAR RAYLEIGH-SCATTERING RESULTS IN HELIUM AIR MIXING EXPERIMENTS IN A MACH-6 WIND-TUNNEL SO APPLIED OPTICS LA English DT Article ID FLUORESCENCE; ABSORPTION AB Planar Rayleigh scattering measurements with an argon-fluoride excimer laser are performed to investigate helium mixing into air at supersonic speeds. The capability of the Rayleigh scattering technique for flow visualization of a turbulent environment is demonstrated in a large-scale, Mach-6 facility. The detection limit obtained with the present setup indicates that planar, quantitative measurements of density can be made over a large cross-sectional area (5 cm x 10 cm) of the flow field in the absence of clusters. C1 CALTECH,PASADENA,CA 91125. RP SHIRINZADEH, B (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 14 TC 11 Z9 11 U1 1 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 OCT 20 PY 1992 VL 31 IS 30 BP 6529 EP 6534 PG 6 WC Optics SC Optics GA JR914 UT WOS:A1992JR91400022 PM 20733871 ER PT J AU GRADWOHL, BA FRIEMAN, JA AF GRADWOHL, BA FRIEMAN, JA TI DARK MATTER, LONG-RANGE FORCES, AND LARGE-SCALE STRUCTURE SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; COSMOLOGY, THEORY; EARLY UNIVERSE; ELEMENTARY PARTICLES; LARGE-SCALE STRUCTURE OF UNIVERSE ID REDSHIFT-DISTANCE SAMPLES; MICROWAVE BACKGROUND ANISOTROPIES; DENSITY FIELDS; EQUIVALENCE PRINCIPLE; ELLIPTICAL GALAXIES; STREAMING MOTIONS; GOLDSTONE BOSONS; GALACTIC HALOS; MISSING MASS; COMA CLUSTER AB If the dark matter in galaxies and clusters is nonbaryonic, it can interact with additional long-range fields that are invisible to experimental tests of the equivalence principle. We discuss the astrophysical and cosmological implications of a long-range force coupled only to the dark matter and find rather tight constraints on its strength. If the force is repulsive (attractive), the masses of galaxy groups and clusters (and the mean density of the universe inferred from them) have been systematically underestimated (overestimated). Such an interaction also has unusual implications for the growth of large-scale structure: a repulsive (attractive) force relatively enhances (suppresses) the growth of density perturbations on large scales and automatically generates a bias (antibias) between baryonic and nonbaryonic matter. We explore the consequent effects on the two-point correlation function, large-scale velocity flows, and microwave background anisotropies, for models with initial scale-invariant adiabatic perturbations and cold dark matter. C1 NASA,FERMI NATL ACCELERATOR LAB,FERMILAB ASTRPHYS CTR,BATAVIA,IL 60510. NR 83 TC 66 Z9 66 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 OCT 20 PY 1992 VL 398 IS 2 BP 407 EP 424 DI 10.1086/171865 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR890 UT WOS:A1992JR89000001 ER PT J AU RABIN, D DOWDY, JF AF RABIN, D DOWDY, JF TI PERVASIVE VARIABILITY IN THE QUIET SOLAR TRANSITION REGION SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, ACTIVITY; SUN, TRANSITION REGION; ULTRAVIOLET, SOLAR SYSTEM ID CORONAL BRIGHT POINTS; SUN; MICROFLARES; EMISSION; NETWORK; LINES AB We study the temporal variability of the quiet solar transition region on scales of 5" and 5.5 minutes using a 44 minute time series of extreme ultraviolet spectroheliograms from the Harvard experiment on Skylab. Six observed spectral lines cover the full temperature range of the transition plasma (10(4) less than or similar T less than or similar 10(6) K). Because visual examination of the time series emphasizes unusually bright events, we perform a statistical analysis to answer the more general question: "What fraction of spatial elements shows intensity variations significantly above noise?" By comparing the temporal intensity fluctuations at each spatial location with an independent estimate of instrumental noise, we find that the data are consistent with the following hypothesis: the EUV intensity in every spatial resolution element varies on a time scale of minutes by 10%-30%. For the spectral line with the highest mean signal (C III lambda977), 93% of the spatial elements are variable at a high level of significance (0.05). For all lines, the fractional amplitude of the temporal variations is nearly independent of mean intensity. The amplitude of the fractional variability is highest (approximately 32%) for O IV (T almost-equal-to 1.5 X 10(5) K). Intensity fluctuations at a given location are significantly correlated between spectral lines. The bulk of the fluctuating power arises from locations with a mean intensity within 1 sigma of the average, not from rare bright points. The pervasiveness and spatial uniformity of temporal variability in the transition region suggest that it is produced and modulated by small-scale magnetic activity. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SOLAR SCI BRANCH ES52,HUNTSVILLE,AL 35812. RP RABIN, D (reprint author), NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,POB 26732,TUCSON,AZ 85726, USA. NR 35 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 OCT 20 PY 1992 VL 398 IS 2 BP 665 EP 681 DI 10.1086/171891 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR890 UT WOS:A1992JR89000027 ER PT J AU KASTNER, SO BHATIA, AK AF KASTNER, SO BHATIA, AK TI ON THE CALCULATION OF ATOMIC TERM POPULATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC DATA; ATOMIC PROCESSES ID IONS; SEQUENCE AB The usefulness of calculations on model atomic term systems which can give spectral multiplet intensities is emphasized, in contrast to more detailed level calculations which are not always feasible because of lack of appropriate atomic data. A more general expression for the multiplet radiative transition rate is proposed to facilitate term representations. The differences between term and level representations are discussed quantitatively with respect to a model three-level atom and real examples of the C III and Ne IV ions. It is shown that term representations fail at lower densities when level inverse lifetimes within terms differ by only a few orders of magnitude. In such cases one must resort to other methods; a hybrid calculation is therefore proposed to fill this need and is carried out for the C III ion to demonstrate its feasibility and validity. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP KASTNER, SO (reprint author), MATH SCI CONSULTANTS INC,I-A RIDGE RD,GREENBELT,MD 20770, USA. NR 12 TC 7 Z9 7 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 OCT 20 PY 1992 VL 398 IS 2 BP 698 EP 705 DI 10.1086/171894 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR890 UT WOS:A1992JR89000030 ER PT J AU WAINSCOAT, RJ COHEN, M VOLK, K WALKER, HJ SCHWARTZ, DE AF WAINSCOAT, RJ COHEN, M VOLK, K WALKER, HJ SCHWARTZ, DE TI A MODEL OF THE 8-25 MICRON POINT-SOURCE INFRARED SKY SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 NASA,SETI INST,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF BERKELEY,RADIOASTRON LAB,BERKELEY,CA 94720. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1992 VL 398 IS 2 BP 711 EP 711 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR890 UT WOS:A1992JR89000035 ER PT J AU MALONEY, P AF MALONEY, P TI LOW-REDSHIFT LYMAN-ALPHA ABSORPTION-LINES AND THE DARK MATTER HALOS OF DISK GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY, OBSERVATIONS; DARK MATTER; GALAXIES, INTERSTELLAR MATTER; QUASARS, ABSORPTION LINES ID H-I; CLOUDS; EVOLUTION; FIELD; QSOS AB Ultraviolet observations of the low-redshift quasar 3C 273 using the Hubble Space Telescope have revealed many more Lyman-alpha absorption lines than would be expected from extrapolation of the absorption systems seen toward QSOs at z approximately 2. Here I show that these absorption lines can plausibly be produced by gas at large radii in the disks of spiral and irregular galaxies; the gas is confined by the dark matter halos and ionized and heated by the extragalactic radiation field. This scenario does not require the extragalactic ionizing radiation field to decline as rapidly with decreasing z as the QSO emissivity. Observations of Lyalpha absorption through the halos of known galaxies at low redshift will constrain both the extragalactic background and the properties of galactic halos. RP MALONEY, P (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 31 TC 36 Z9 36 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 OCT 20 PY 1992 VL 398 IS 2 BP L89 EP L93 DI 10.1086/186584 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR892 UT WOS:A1992JR89200004 ER PT J AU SCHMELZ, JT SABA, JLR STRONG, KT AF SCHMELZ, JT SABA, JLR STRONG, KT TI RESONANCE SCATTERING OF FE-XVII - A DENSITY DIAGNOSTIC SO ASTROPHYSICAL JOURNAL LA English DT Article DE LINE, FORMATION; SUN, CORONA; SUN, X-RAYS, GAMMA-RAYS ID ACTIVE REGIONS; LINE RATIOS; SOLAR AB Resonance scattering of the 15.01 angstrom Fe XVII line, found to be important by Rugge & McKenzie, provides a new density diagnostic for solar active regions that is not subject to the lower density limit of the competing diagnostic. For a "typical" active region, over 50% of the photons for this resonance line could be scattered out of the line of sight. The effect is much stronger for this line than for any other line in the soft X-ray part of the spectrum used routinely to determine active region electron temperatures, emission measures, or densities. Once understood and accounted for in the analysis, the resonance scattering of the 15.01 angstrom Fe XVII line leads to a direct measurement of the density of the active region plasma. In the four active regions studied here, the derived densities range is 1-4 x 10(9) cm-3. C1 LOCKHEED PALO ALTO RES LABS,SOLAR & ASTROPHYS GRP,PALO ALTO,CA 94304. RP SCHMELZ, JT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,LOCKHEED SOLAR & ASTROPHYS GRP,CODE 682,GREENBELT,MD 20771, USA. NR 27 TC 27 Z9 28 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 OCT 20 PY 1992 VL 398 IS 2 BP L115 EP L118 DI 10.1086/186590 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR892 UT WOS:A1992JR89200010 ER PT J AU DARNELL, WL STAYLOR, WF GUPTA, SK RITCHEY, NA WILBER, AC AF DARNELL, WL STAYLOR, WF GUPTA, SK RITCHEY, NA WILBER, AC TI SEASONAL-VARIATION OF SURFACE RADIATION BUDGET DERIVED FROM INTERNATIONAL SATELLITE CLOUD CLIMATOLOGY PROJECT C1 DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LONGWAVE IRRADIANCE; OCEAN SURFACE; METHODOLOGY; VALIDATION; MODELS AB Surface radiation budget data are presented for the midseasonal months of July and October of 1983 and January and April of 1984. These data allow examination for the first time of geographical and seasonal variations of the entire surface radiation budget from pole to pole. The latest flux estimation techniques have been used along with data from the International Satellite Cloud Climatology Project (ISCCP) and the Earth Radiation Budget Experiment (ERBE). Regional, zonal, and hemispheric distributions of the downward and net components of both shortwave and longwave fluxes and of the net total surface fluxes are determined. Seasonal flux variation per region, expressed as flux range, is illustrated for these components also. The estimated fluxes appear to be accurate to about 16 W m-2 on a global average, based on sensitivity analyses and comparisons with ground data. An analysis of flux errors showed that most of the error was attributable to errors in input data. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP DARNELL, WL (reprint author), NASA,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. RI wilber, anne/F-6270-2011 NR 22 TC 148 Z9 154 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-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1992 VL 97 IS D14 BP 15741 EP 15760 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JU835 UT WOS:A1992JU83500004 ER PT J AU PARRISH, DD HAHN, CJ WILLIAMS, EJ NORTON, RB FEHSENFELD, FC SINGH, HB SHETTER, JD GANDRUD, BW RIDLEY, BA AF PARRISH, DD HAHN, CJ WILLIAMS, EJ NORTON, RB FEHSENFELD, FC SINGH, HB SHETTER, JD GANDRUD, BW RIDLEY, BA TI INDICATIONS OF PHOTOCHEMICAL HISTORIES OF PACIFIC AIR MASSES FROM MEASUREMENTS OF ATMOSPHERIC TRACE SPECIES AT POINT ARENA, CALIFORNIA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PEROXYACETYL NITRATE PAN; NON-METHANE HYDROCARBONS; MARINE BOUNDARY-LAYER; ODD-NITROGEN NOY; NIWOT-RIDGE; ORGANIC NITRATES; VERTICAL-DISTRIBUTION; RURAL TROPOSPHERE; UNITED-STATES; NITRIC-OXIDE AB Measurements of light hydrocarbons, ozone, peroxyacetyl nitrate (PAN), HNO3, NO3-, NO(x), NO(y), and meteorological parameters were made during a 10-day period in April and May 1985 at Point Arena, a coastal inflow site on the Pacific Ocean in northern California. The meteorological measurements indicate that during this study the sampled air was usually from the marine boundary layer with little land influence on the meteorological parameters. In this marine air the mixing ratios of the alkanes, ozone, PAN, and HNO3 showed strong correlations coincident with variations in the origins of calculated air parcel trajectories and with variations in the ratios of the light alkanes. This variation in the ratios is attributed to different degrees of photochemical aging of the alkanes that are generally consistent with the calculated trajectories. This behavior indicates that the alkane levels are determined by transport to the marine area from continental sources, most likely Asian, followed by photochemical removal over the Pacific Ocean. Since the concentrations of PAN and ozone correlate well with the alkane ratios, it is concluded that the observed PAN and ozone were dominated by continental sources and removal processes in the marine areas. This and other marine studies have observed a strong correlation of PAN and ozone, and it is suggested that production over the continents, transport to the marine areas, and parallel removal processes account for much of the observed correlation. From the correlation of these two species with the measured alkane ratios, approximate net lifetimes of PAN and ozone in the marine troposphere of less-than-or-equal-to 2.5 and greater-than-or-equal-to 19 days, respectively, are derived. The primary conclusion is that the alkanes, ozone, and PAN in these air parcels from the Pacific marine troposphere are dominated by transport from continental sources and removal by photochemical processes. Direct emissions of the alkanes and in situ photochemical production of PAN and ozone from precursors emitted into the marine region from the surface or the stratosphere must play less important roles. Similar indications of continental influence in marine areas have been seen in other studies of ozone, the sulfur cycle, oxidized nitrogen, and hydrocarbons. It is suggested that the ratios of the light alkanes provide photochemical "clocks" that are useful for gauging the importance of continental influence in a particular marine measurement. C1 UNIV COLORADO,NOAA,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. RP PARRISH, DD (reprint author), NOAA,AERON LAB,325 BROADWAY,BOULDER,CO 80303, USA. RI Williams, Eric/F-1184-2010; Parrish, David/E-8957-2010; Fehsenfeld, Frederick/I-4876-2013 OI Parrish, David/0000-0001-6312-2724; NR 62 TC 168 Z9 166 U1 3 U2 27 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 OCT 20 PY 1992 VL 97 IS D14 BP 15883 EP 15901 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JU835 UT WOS:A1992JU83500014 ER PT J AU TONG, WM SNYDER, EJ WILLIAMS, RS YANASE, A SEGAWA, Y ANDERSON, MS AF TONG, WM SNYDER, EJ WILLIAMS, RS YANASE, A SEGAWA, Y ANDERSON, MS TI ATOMIC FORCE MICROSCOPE STUDIES OF CUCL ISLAND FORMATION ON CAF2(111) SUBSTRATES SO SURFACE SCIENCE LA English DT Letter ID GROWTH; LUMINESCENCE; FILMS AB We have grown by molecular beam epitaxy (MBE) CuCl thin films at various thicknesses and substrate temperatures on CaF2(111) substrates. Atomic force microscope (AFM) topographs reveal that islanding is the dominant growth mechanism. Quantitative analysis of the AFM data enabled us to determine the amount of the substrate remaining exposed after the deposition as well as the total amount of CuCl deposited. We calculated the reciprocal-space height correlation function, [\h(q, t)\2], for each of our films and compared them to the predictions of the shadowing growth theory, which enabled us to extract the important kinetic parameter of surface diffusion length for the growth condition of each of the four films. C1 RIKEN,INST PHYS & CHEM RES,FRONTIER RES PROGRAM,PHOTODYNAM RES CTR,AOBA KU,SENDAI 98932,JAPAN. JET PROP LAB,SPACE MAT SCI & TECHNOL SECT,PASADENA,CA 91109. RP TONG, WM (reprint author), UNIV CALIF LOS ANGELES,DEPT CHEM & BIOCHEM,CTR SOLID STATE SCI,LOS ANGELES,CA 90024, USA. RI Tong, William/D-2564-2010; Williams, R. Stanley/A-8281-2009 OI Williams, R. Stanley/0000-0003-0213-4259 NR 12 TC 16 Z9 16 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD OCT 20 PY 1992 VL 277 IS 3 BP L63 EP L69 PG 7 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA JU938 UT WOS:A1992JU93800001 ER PT J AU PATNAIK, SN HOPKINS, DA AIELLO, RA BERKE, L AF PATNAIK, SN HOPKINS, DA AIELLO, RA BERKE, L TI IMPROVED ACCURACY FOR FINITE-ELEMENT STRUCTURAL-ANALYSIS VIA AN INTEGRATED FORCE METHOD SO COMPUTERS & STRUCTURES LA English DT Article ID COMPATIBILITY CONDITIONS; CONSTRAINTS; BEHAVIOR AB Finite element structural analysis based on the original displacement (stiffness) method has been researched and developed for over three decades. Although today it dominates the scene in terms of routine engineering use, the stiffness method does suffer from certain deficiencies. Various alternate analysis methods, commonly referred to as the mixed and hybrid methods, have been promoted in an attempt to compensate for some of these limitations. In recent years two methods for finite element analyses of structures, within the framework of the original force method concept, have been introduced. These are termed the 'integrated force method' and the 'dual integrated force method'. A comparative study was carried out to determine the accuracy of finite element analyses based on the stiffness method, a mixed method, and the new integrated force and dual integrated force methods. The numerical results were obtained with the following software: MSC/NASTRAN and ASKA for the stiffness method; an MHOST implementation for a mixed method; a GIFT for the integrated force methods. For the cases considered, the results indicate that, on an overall basis, the stiffness and mixed methods present some limitations. The stiffness method typically requires a large number of elements in the model to achieve acceptable accuracy. The MHOST mixed method tends to achieve a higher level of accuracy for coarse models than does the stiffness method as implemented by MSC/NASTRAN and ASKA. The two integrated force methods, which bestow simultaneous emphasis on stress equilibrium and strain compatibility, yield accurate solutions with fewer elements in a model. The full potential of these new integrated force methods remains largely unexploited, and they hold the promise of spawning new finite element structural analysis tools. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP PATNAIK, SN (reprint author), OHIO AEROSP INST,BROOK PK,OH 44142, USA. NR 43 TC 8 Z9 8 U1 0 U2 0 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 OCT 17 PY 1992 VL 45 IS 3 BP 521 EP 542 DI 10.1016/0045-7949(92)90437-5 PG 22 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA JZ845 UT WOS:A1992JZ84500011 ER PT J AU HYDE, TM WU, LC KRASNOV, IB SIGWORTH, SK DAUNTON, NG DAMELIO, F AF HYDE, TM WU, LC KRASNOV, IB SIGWORTH, SK DAUNTON, NG DAMELIO, F TI QUANTITATIVE AUTORADIOGRAPHIC ANALYSIS OF MUSCARINIC CHOLINERGIC AND GABA(A) (BENZODIAZEPINE) RECEPTORS IN THE FOREBRAIN OF RATS FLOWN ON THE SOVIET BIOSATELLITE COSMOS 2044 SO BRAIN RESEARCH LA English DT Note DE AUTORADIOGRAPHY; GAMMA-AMINOBUTYRIC ACID; RECEPTOR; CHOLINERGIC; FOREBRAIN ID DIFFERENTIAL RESPONSE; STRIATAL DOPAMINE; BASAL GANGLIA; 6-HYDROXYDOPAMINE; LOCALIZATION; BRAIN; ORGANIZATION; SUBTYPES AB The quantitative autoradiographic analysis of muscarinic cholinergic and GABA(A) (benzodiazepine) receptors was performed on selected regions of the cerebral cortex and striatum of rats flown in the Soviet Biosatellite COSMOS 2044. An age- and strain-matched synchronous ground-based control group was employed for comparison. Muscarinic cholinergic receptor density was found to be significantly lower in the striatum of the flight animals as compared with that in the synchronous control group. No significant differences between flight and synchronous control groups were found in the other regions examined. GABA(A) (benzodiazepine) receptors showed no significant differences between the flight and control groups in any of the regions sampled. Although additional studies are needed to reach definitive conclusions, the decrease in muscarinic cholinergic receptors observed in the striatum suggests spaceflight-related alterations in motor activity. C1 NASA,AMES RES CTR,MAIL STOP 261-3,MOFFETT FIELD,CA 94035. NIMH,CTR NEUROSCI,INTRAMURAL RES PROGRAM,CLIN BRAIN DISORDERS BRANCH,WASHINGTON,DC 20032. SAN JOSE STATE UNIV FDN,SAN JOSE,CA 95192. MOSCOW BIOMED PROBLEMS INST,MOSCOW,USSR. NR 18 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0006-8993 J9 BRAIN RES JI Brain Res. PD OCT 16 PY 1992 VL 593 IS 2 BP 291 EP 294 DI 10.1016/0006-8993(92)91321-5 PG 4 WC Neurosciences SC Neurosciences & Neurology GA JV507 UT WOS:A1992JV50700019 PM 1333347 ER PT J AU BURROWS, A FRYXELL, BA AF BURROWS, A FRYXELL, BA TI AN INSTABILITY IN NEUTRON-STARS AT BIRTH SO SCIENCE LA English DT Article ID SUPERNOVA EXPLOSIONS; II SUPERNOVAE; COLLAPSE; CONVECTION; MECHANISM AB Calculations with a two-dimensional hydrodynamic simulation show that a generic Raleigh-Taylor-like instability occurs in the mantles of nascent neutron stars, that it is possibly violent, and that the standard spherically symmetric models of neutron star birth and supernova explosion may be inadequate. Whether this "convective" instability is pivotal to the supernova mechanism, pulsar magnetic fields, or a host of other important issues that attend stellar collapse remains to be seen, but its existence promises to modify all questions concerning this most energetic of astronomical phenomena. C1 UNIV ARIZONA,DEPT ASTRON,TUCSON,AZ 85721. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BURROWS, A (reprint author), UNIV ARIZONA,DEPT PHYS,TUCSON,AZ 85721, USA. NR 29 TC 97 Z9 97 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 OCT 16 PY 1992 VL 258 IS 5081 BP 430 EP 434 DI 10.1126/science.258.5081.430 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JT775 UT WOS:A1992JT77500026 PM 17833138 ER PT J AU STALLCOP, JR BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR LEVIN, E AF STALLCOP, JR BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR LEVIN, E TI THEORETICAL-STUDY OF HYDROGEN AND NITROGEN INTERACTIONS - N-H TRANSPORT CROSS-SECTIONS AND COLLISION INTEGRALS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID LONG-RANGE INTERACTION; DISPERSION COEFFICIENTS; COMBINING RULE; SYSTEMS; ATOMS; X3-SIGMA; MODEL; STATE AB Potential energy curves have been calculated for the X3SIGMA- and 5SIGMA- states of NH using a complete-active-space self-consistent-field/multireference configuration-interaction procedure and extensive Gaussian basis sets. An accurate dipole moment function is computed for the X3SIGMA- state. Transport cross sections have been calculated for the collisions of hydrogen and nitrogen atoms in their ground states. The mean transport cross sections are tabulated for collision energies in the range 0.0001-1 E(h); the mean collision integrals are listed for temperatures between 100 and 100 000 K. The ab initio energies for the 5SIGMA- state of NH are found to be consistent with the results of correlation studies and agree well with the prediction from combining relations using the energies of the highest spin states of H-2 and N2. C1 NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035. RP STALLCOP, JR (reprint author), NASA,AMES RES CTR,DIV THERMOSCI,COMPUTAT CHEM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 39 TC 29 Z9 29 U1 0 U2 4 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 OCT 15 PY 1992 VL 97 IS 8 BP 5578 EP 5585 DI 10.1063/1.463765 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JU516 UT WOS:A1992JU51600031 ER PT J AU MASSOM, RA AF MASSOM, RA TI OBSERVING THE ADVECTION OF SEA ICE IN THE WEDDELL SEA USING BUOY AND SATELLITE PASSIVE MICROWAVE DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SOUTHERN-OCEAN; PACK ICE; CIRCULATION; DRIFT AB This study examines the progress and behavior of an area of sea ice as it drifts from the south-western Weddell Sea by using data from four buoys tracked by Nimbus 6 and concurrent ice concentrations retrieved from Nimbus 7 scanning multichannel microwave radiometer data. It covers the entire growth season of 1980. The overall drift characteristics, and their relationship to ice edge displacement, are examined within the framework of four zones. Three phases are identified in the large-scale behavior of the Weddell sea ice cover, namely, a rapid equatorward and eastward advance, a quasi-equilibrium phase, and a period of rapid recession. A broad division is made between the sectors to the east and west of 35-40-degrees-W in terms of the nature of ice edge advance. Transient departures from the mean northward advection are linked to the passage of cyclones; certain such events may be significant in terms of the formation and maintenance of the region of highly consolidated perennial ice observed in the western Weddell Sea. Mean daily drift rates (up to 0.9 m s-1) from within the central-western Weddell pack are high in 1980, particularly early in the growth season and when compared with rates to the west of 50-degrees-W. Outbreaks of cold continental air alternate with incursions of relatively warm air from the north; warm conditions are recorded as far as 1200 km in from the ice edge in winter. Closed loops in the buoy trajectories, which are clockwise to the south of 63-degrees-S, reverse to become anticlockwise to the north. Mid-ocean islands impede the eastward progress of the ice. A coherence is noted in the response of the buoys to the passage of storms, even though the buoys separated by a distance of over 100 km. RP MASSOM, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NRC,OCEANS & ICE BRANCH,CODE 971,GREENBELT,MD 20771, USA. NR 52 TC 30 Z9 31 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD OCT 15 PY 1992 VL 97 IS C10 BP 15559 EP 15572 DI 10.1029/92JC01198 PG 14 WC Oceanography SC Oceanography GA JT996 UT WOS:A1992JT99600008 ER PT J AU GHISELLINI, G CELOTTI, A GEORGE, IM FABIAN, AC AF GHISELLINI, G CELOTTI, A GEORGE, IM FABIAN, AC TI THE ROLE OF ELECTRON POSITRON PAIRS IN PARSEC-SCALE RADIO JETS SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE PLASMAS; RADIATION MECHANISMS, MISCELLANEOUS; GALAXIES, JETS; RADIO CONTINUUM, GALAXIES ID COMPACT NONTHERMAL SOURCES; VLBI OBSERVATIONS; SPECTRAL PROPERTIES; COMPLETE SAMPLE; BLAZARS; DISTRIBUTIONS; ABSORPTION; OBJECTS; QUASARS; PHYSICS AB We investigate the hypodiesis that the parsec-scale jets observed in extragalactic objects consist of an electron-positron (e+/-) pair plasma outflowing from the compact, X-ray emitting region of the source. Due to annihilation in the innermost regions, there is an upper limit on the number of e+/- pairs that can reach the parsec-scale jet. On the other hand, there is a lower limit on the density of particles in the jet: their density must be at least equal to that needed to emit the synchrotron radiation we observe. We derive the latter limit by assuming a power-law electron distribution, with a low-energy cut-off. By comparing these two limits, we find that the constituents of parsec-scale jets may be e+/- pairs produced in the innermost regions only if their minimum energy is greater than approximately 50 MeV. Remarkably, the same limit on the minimum particle energy is found in the case of jets consisting of electrons and protons in order that Faraday depolarization is avoided. C1 UNIV CAMBRIDGE, INST ASTRON, CAMBRIDGE CB3 0HA, ENGLAND. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. SCUOLA INT SUPER STUDI AVANZATI, TRIESTE, ITALY. RP GHISELLINI, G (reprint author), OSSERV ASTRON TORINO, PINO TORINESE, TURIN, ITALY. NR 49 TC 37 Z9 37 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 15 PY 1992 VL 258 IS 4 BP 776 EP 786 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JT716 UT WOS:A1992JT71600012 ER PT J AU MARAIS, DJD STRAUSS, H SUMMONS, RE HAYES, JM AF MARAIS, DJD STRAUSS, H SUMMONS, RE HAYES, JM TI CARBON ISOTOPE EVIDENCE FOR THE STEPWISE OXIDATION OF THE PROTEROZOIC ENVIRONMENT SO NATURE LA English DT Article ID CENTRAL AUSTRALIA; AMADEUS BASIN; RECORD; OCEANS; EVAPORITE; PALEOSOL; DEPOSITS; DIOXIDE; SULFATE; OXYGEN AB The oxidation of the Earth's crust and the increase in atmospheric oxygen early in Earth history have been linked to the accumulation of reduced carbon in sedimentary rocks. Trends in the carbon isotope composition of sedimentary organic carbon and carbonate show that during the Proterozoic aeon (2.5-0.54 Gyr ago) the organic carbon reservoir grew in size, relative to the carbonate reservoir. This increase, and the concomitant release of oxidizing power in the environment, occurred mostly during episodes of global rifting and orogeny. C1 RUHR UNIV BOCHUM, INST GEOL, W-4630 BOCHUM 1, GERMANY. BUR MINERAL RESOURCES, CANBERRA, ACT 2605, AUSTRALIA. INDIANA UNIV, DEPT GEOL SCI, BIOGEOCHEM LABS, BLOOMINGTON, IN 47405 USA. INDIANA UNIV, DEPT CHEM, BLOOMINGTON, IN 47405 USA. RP MARAIS, DJD (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 59 TC 252 Z9 257 U1 7 U2 22 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD OCT 15 PY 1992 VL 359 IS 6396 BP 605 EP 609 DI 10.1038/359605a0 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JT824 UT WOS:A1992JT82400046 PM 11536507 ER PT J AU THOMPSON, DJ ARZOUMANIAN, Z BERTSCH, DL BRAZIER, KTS DAMICO, N FICHTEL, CE FIERRO, JM HARTMAN, RC HUNTER, SD JOHNSTON, S KANBACH, G KASPI, VM KNIFFEN, DA LIN, YC LYNE, AG MANCHESTER, RN MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NEL, HI NICE, D NOLAN, PL PINKAU, K ROTHERMEL, H SCHNEID, EJ SOMMER, M SREEKUMAR, P TAYLOR, JH AF THOMPSON, DJ ARZOUMANIAN, Z BERTSCH, DL BRAZIER, KTS DAMICO, N FICHTEL, CE FIERRO, JM HARTMAN, RC HUNTER, SD JOHNSTON, S KANBACH, G KASPI, VM KNIFFEN, DA LIN, YC LYNE, AG MANCHESTER, RN MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NEL, HI NICE, D NOLAN, PL PINKAU, K ROTHERMEL, H SCHNEID, EJ SOMMER, M SREEKUMAR, P TAYLOR, JH TI PULSED HIGH-ENERGY GAMMA-RAYS FROM THE RADIO PULSAR PSR1706-44 SO NATURE LA English DT Article ID COS-B; EMISSION; RADIATION; TELESCOPE; CRAB; VELA AB OF the more than 500 known radio pulsars, only three have been detected as gamma-ray sources. Using the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory satellite, we have detected pulsed gamma-radiation, above 100 MeV in energy, from a fourth radio pulsar, PSR1706-44. Within the pulse period of 102 ms, the gamma-emission forms a single broad peak, in contrast to the two narrow peaks seen in the other high-energy gamma-ray pulsars. The emission mechanism in all cases is probably the same, the differences arising from the geometry of the magnetic and rotation axes and the line of sight. In these pulsars, gamma-ray emission accounts for as much as 1% of the total neutron star spin-down energy, much more than emerges at optical or radio frequencies, so study of this emission is important in understanding pulsar emission and evolution. C1 PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. MAX PLANCK INST EXTRATERRESTR PHYS,W-8046 GARCHING,GERMANY. UNIV PALERMO,IST AGRON,I-90134 PALERMO,ITALY. CNR,IST RADIOASTRON,I-40126 BOLOGNA,ITALY. STANFORD UNIV,DEPT PHYS,STANFORD,CA 94305. STANFORD UNIV,WW HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. HAMPDEN SYDNEY COLL,DEPT PHYS,HAMPDEN SYDNEY,VA 23943. UNIV MANCHESTER,DEPT PHYS,MACCLESFIELD SK11 9DL,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOCIATES,GREENBELT,MD 20771. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP THOMPSON, DJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,COMPTON OBSERV SCI SUPPORT CTR,GREENBELT,MD 20771, USA. RI D'Amico, Nichi/A-5715-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; Nolan, Patrick/A-5582-2009 OI Thompson, David/0000-0001-5217-9135; NR 22 TC 111 Z9 112 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 OCT 15 PY 1992 VL 359 IS 6396 BP 615 EP 616 DI 10.1038/359615a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JT824 UT WOS:A1992JT82400048 ER PT J AU DODELSON, S TURNER, MS AF DODELSON, S TURNER, MS TI NONEQUILIBRIUM NEUTRINO STATISTICAL-MECHANICS IN THE EXPANDING UNIVERSE SO PHYSICAL REVIEW D LA English DT Article ID NUCLEOSYNTHESIS; RATES; WEAK AB We study neutrino decoupling in the early Universe (t approximately sec, T approximately MeV) by integrating the Boltzmann equations that govern the neutrino phase-space distribution functions. In particular, we compute the distortions in the nu(e) and nu(mu)/nu(tau) phase-space distributions that arise in the standard cosmology due to e+/- annihilations. These distortions are nonthermal, with the effective neutrino temperature increasing with neutrino momentum, approaching a 0.7% increase for electron neutrinos and a 0.3% increase for mu and tau neutrinos at the highest neutrino momenta, and correspond to an increase in the energy density of nu(e)'s of about 1.2% and in the energy density of nu(mu)/nu(tau)'s of about 0.5% (roughly one additional relic neutrino per cm-3 per species). The distortion for electron neutrinos is larger than that for mu and tau neutrinos because electron neutrinos couple to e+/-'s through both charged- and neutral-current interactions. Our results graphically illustrate that neutrino decoupling is a continuous process which is momentum dependent. Because of subtle cancellations, these distortions lead to only a tiny change in the predicted primordial He-4 abundance, DELTAY congruent-to 1-2 X 10(-4). C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS & ASTRON,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTROPHYS,CHICAGO,IL 60637. RP DODELSON, S (reprint author), FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 18 TC 77 Z9 77 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 1992 VL 46 IS 8 BP 3372 EP 3387 DI 10.1103/PhysRevD.46.3372 PG 16 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA JV113 UT WOS:A1992JV11300021 ER PT J AU GARY, CK AF GARY, CK TI MATRIX-VECTOR MULTIPLICATION USING DIGITAL PARTITIONING FOR MORE ACCURATE OPTICAL COMPUTING SO APPLIED OPTICS LA English DT Article ID LINEAR ALGEBRA PROCESSORS; COMPUTATION; NOISE AB Digital partitioning offers a flexible means of increasing the accuracy of an optical matrix-vector processor. This algorithm can be implemented with the same architecture required for a purely analog processor, which gives optical matrix-vector processors the ability to perform high-accuracy calculations at speeds comparable with or greater than electronic computers as well as the ability to perform analog operations at a much greater speed. Digital partitioning is compared with digital multiplication by analog convolution, residue number systems, and redundant number representation in terms of the size and the speed required for an equivalent throughput as well as in terms of the hardware requirements. Digital partitioning and digital multiplication by analog convolution are found to be the most efficient algorithms if coding time and hardware are considered, and the architecture for digital partitioning permits the use of analog computations to provide the greatest throughput for a single processor. To our knowledge this is the first study to propose the use of digital partitioning for optical matrix processing. RP GARY, CK (reprint author), NASA,AMES RES CTR,MAIL STOP 244-4,MOFFETT FIELD,CA 94035, USA. NR 13 TC 22 Z9 26 U1 1 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD OCT 10 PY 1992 VL 31 IS 29 BP 6205 EP 6211 PG 7 WC Optics SC Optics GA JQ534 UT WOS:A1992JQ53400009 PM 20733832 ER PT J AU UNWIN, SC WEHRLE, AE AF UNWIN, SC WEHRLE, AE TI KINEMATICS OF THE PARSEC-SCALE RELATIVISTIC JET IN 3C-345 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, JETS; GALAXIES, KINEMATICS AND DYNAMICS; QUASARS, INDIVIDUAL (3C-345); RADIO CONTINUUM, GALAXIES; TECHNIQUES, INTERFEROMETRIC ID COMPACT RADIO-SOURCE; M87 JET; MOTION; MAPS; GHZ; RESOLUTION; NUCLEI; 3C273 AB We have made two VLBI images of the nucleus of the quasar 3C 345 from observations in 1989 and 1990 with 1 mas (4 pc) resolution. These 5 GHz images have a dynamic range greater than 1000:1 and show the well-known compact core and superluminal jet, whose subcomponents move away from the core at almost-equal-to 0.3 mas yr-1. Within 5 mas of the nucleus the jet expands with an apparent opening angle of almost-equal-to 25-degrees; between 5 and 11 mas the boundary is approximately cylindrical. In this latter region, the jet appears to be edge-brightened and is suggestive of tangled or perhaps helically wound filaments, consistent with models in which the emission is confined to a boundary layer between the jet and the confining medium. A prominent gap in the jet is found between approximately 11 and 15 mas radius from the nucleus, perhaps resulting from a change in the angle theta which the jet axis makes with the line of sight, but more likely from a sudden reduction in emissivity. Jet emission resumes abruptly at a radius of 15 mas, where an extended component "C1" is found with a surprising morphology, namely a sharp "edge" (representing a flat surface edge-on) facing the core. The apparent opening angle of the jet flares at this point, enlarging to almost-equal-to 35-degrees, perhaps the result of a shock. We show that this component is also superluminal, at a deprojected distance of more than 600 pc from the nucleus. This jet morphology has many similarities with the shock (knot "A") seen in the jet of the radio galaxy M87. Relativistic aberration affects the appearance of the jet: photons received at Earth from the " edge " of C1 were emitted (in the component's rest frame) almost perpendicular to the jet direction. A standard relativistic twin-jet model is consistent with our observations and with imaging at other frequencies at many epochs. Using this model and some simplifying assumptions, we derive jet fluid Lorentz factor gamma and orientation theta from four measured quantities: (a) superluminal motion; (b) a lower limit to the Doppler factor from measured inverse-Compton X-ray emission; (c) limits to the jet to counterjet ratio-no counter-jet detection has been made on parsec scales; (d) the effect of relativistic aberration on jet viewing angle. The derived values (gamma = 7.2 +/- 1.1; theta = 6.8-degrees +/- 1.5-degrees) are the most tightly constrained of any known relativistic jet in an extragalactic object. C1 JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91109. RP UNWIN, SC (reprint author), CALTECH,OWENS VALLEY RADIO OBSERV,105-24,PASADENA,CA 91125, USA. NR 46 TC 36 Z9 36 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 OCT 10 PY 1992 VL 398 IS 1 BP 74 EP 86 DI 10.1086/171837 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ397 UT WOS:A1992JQ39700008 ER PT J AU KORYCANSKY, DG AF KORYCANSKY, DG TI AN OFF-CENTER POINT EXPLOSION IN A RADIALLY STRATIFIED MEDIUM - KOMPANEETS APPROXIMATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDRODYNAMICS; ISM, BUBBLES; SHOCK WAVES AB The Kompaneets approximation describes the evolution of a blast wave in a medium of variable density. The case studied here is an off-center explosion in a medium that is radially stratified according to a power law: rho(r) = rho0(r/a)-omega. Analytic solutions can be found by means of a coordinate transformation in which the shock takes the form of a circle, centered on the initial blast location. The paths followed by points on the shock can also be found analytically. For omega > 2, the asymptotic shape of the shock (at large times, and far from the explosion point) is that of a pair of lines whose opening angle depends on omega. For omega > 5, the shock "blows out" to infinity in a finite time. If it is assumed that the mass behind the shock is swept up into a thin shell that follows the same streamlines as points on the shock front, it is found that most of the mass is deposited quite close to the location of the blast. In general, a vanishingly small amount of mass will be driven to infinity. The effect on a solid core at the origin is briefly considered. The angular extent of the core's surface covered by the shock is found. For 4/3 < omega < 8/3, the entire core may be enveloped in the shock, if the explosion takes place on the surface of the core. The motivation for this work is to assess aspects of earlier work by Korycansky et al. on the possibility that the planet Uranus suffered a large impact early in its history, accounting for its obliquity. They attempted to place constraints on the timing of such an impact relative to the formation of the planet. The results presented here suggest that their conclusions are invalid, as they largely depended on the assumption that the blast could be described by a one-dimensional treatment. RP KORYCANSKY, DG (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 12 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1992 VL 398 IS 1 BP 184 EP 189 DI 10.1086/171847 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ397 UT WOS:A1992JQ39700018 ER PT J AU RETTIG, TW TEGLER, SC PASTO, DJ MUMMA, MJ AF RETTIG, TW TEGLER, SC PASTO, DJ MUMMA, MJ TI COMET OUTBURSTS AND POLYMERS OF HCN SO ASTROPHYSICAL JOURNAL LA English DT Article DE COMETS, GENERAL; MOLECULAR PROCESSES ID HALLEY; P/HALLEY; CHEMISTRY; EMISSION; GRAINS; DUST; HYDROGEN; METHANOL; RADICALS; ENERGIES AB Dramatic cometary outbursts have been noted by observers for many years. These outbursts can sometimes increase the apparent brightness of a comet up to 9 mag and release energy on the order of 10(19) ergs. A number of mechanisms have been suggested for outburst activity; however, none has been generally accepted, HCN is a known constituent of both interstellar icy grain mantles and cometary nuclei, and HCN polymers have been postulated to exist on the dark surface of comets such as P/Halley. Since polymerization is a strongly exothermic process, we investigate the possibility that HCN polymerization can provide the energy needed for outbursts. Polymerization may be continuing in the inhomogeneous interior of comets. In addition, the reactive CN groups in these oligomers can be hydrolyzed and may contribute to CO2 and CO pressure buildup in the interior of comets. C1 UNIV NOTRE DAME,DEPT CHEM & BIOCHEM,NOTRE DAME,IN 46556. NASA,GODDARD SPACE FLIGHT CTR,DIV PLANETARY SYST,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP RETTIG, TW (reprint author), UNIV NOTRE DAME,DEPT PHYS & ASTRON,NOTRE DAME,IN 46556, USA. RI mumma, michael/I-2764-2013 NR 64 TC 58 Z9 58 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 OCT 10 PY 1992 VL 398 IS 1 BP 293 EP 298 DI 10.1086/171857 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ397 UT WOS:A1992JQ39700028 ER PT J AU SCUDDER, JD AF SCUDDER, JD TI ON THE CAUSES OF TEMPERATURE-CHANGE IN INHOMOGENEOUS LOW-DENSITY ASTROPHYSICAL PLASMAS SO ASTROPHYSICAL JOURNAL LA English DT Article DE PLASMAS ID PERPENDICULAR SHOCK-WAVE; SOLAR-WIND ELECTRONS; RESOLVED LAYER; POLAR RAIN; HIGH-BETA; GLOBAL PROCESSES; COLLISIONLESS; ION; ELECTRODYNAMICS; MAGNETOSPHERE AB A kinetic discussion is presented of the temperature changes possible in inhomogeneous, low-density plasmas for a variety of boundary distribution functions that occur in astrophysics. Emphasis is placed on the spatial changes in temperature and their correlations with those of the density caused by time-independent, but spatially varying, conservative potentials; examples from in situ space plasma measurements where these effects have been documented are organized by this approach. Where equivalent polytropes are determined, they are shown to have exponents gamma greater than, equal to, and less than unity. A graphical proof is provided that decelerating forces produce equilibrium temperatures that are anticorrelated with densities provided that the boundary condition is non-Maxwellian. This proof is extended analytically for a generalized Lorentzian distribution to show that they obey a polytrope relation with 0 < gamma < 1. Five factors influence the interactions of a gas with these potentials: (1) the boundary Mach number of the flow, (2) the proximity of the initial velocity distribution to a convected Maxwellian, (3) the relative size of the convection energy and the energy change associated with the potential, (4) the repulsive or attractive nature of the potential, and (5) the collisionality and degree of ionization of the medium. In the presence of spatial variations of the potential energy, general rules for the accompanying temperature profiles are developed. This temperature, the root mean square of the distribution of particle speeds, has a spatial variation for all circumstances except decelerating forces acting on Maxwellian distribution at rest. These changes are observed in numerous in situ contexts of space plasmas as well as in laboratory apparatus with charged particle beams. Considering the generality of the argument and the ubiquity of nonthermal phase-space distributions wherever in situ space plasma measurements are made, and the inability of residual Coulomb scattering in a fully ionized, inhomogeneous plasma to suppress these effects, these considerations raise new possibilities for the interpretation of remote astrophysical observations with conclusions potentially different from those permitted by classical thermodynamical arguments. These new possibilities occur when the traditional plasma fluid closure/truncation schemes are relaxed to address the consequences of nonnegligible suprathermal populations that are routinely sampled by spacecraft. RP SCUDDER, JD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,MAIL CODE 692,GREENBELT,MD 20771, USA. RI Scudder, Jack/D-8417-2013 OI Scudder, Jack/0000-0001-7975-5630 NR 60 TC 184 Z9 184 U1 1 U2 6 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1992 VL 398 IS 1 BP 299 EP & DI 10.1086/171858 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ397 UT WOS:A1992JQ39700029 ER PT J AU SCUDDER, JD AF SCUDDER, JD TI WHY ALL STARS SHOULD POSSESS CIRCUMSTELLAR TEMPERATURE INVERSIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SOLAR WIND; STARS, ATMOSPHERES; STARS, CORONAE; STARS, MASS LOSS ID VELOCITY DISTRIBUTION-FUNCTIONS; SOLAR TRANSITION REGION; MAGNETIC NEUTRAL SHEETS; CORONAL LOOPS; POLAR RAIN; GLOBAL PROCESSES; EVOLVING FIELDS; WIND ELECTRONS; ACTIVE REGION; ENERGY-FLOW AB The consequences are presented of a postulated nonthermal distribution at the point in a stellar atmosphere where the plasma is nearly fully ionized and optically thin. The most immediate consequences are (1) that the temperature and quasi-neutral plasma density become anticorrelated with increasing radius in a thin transition region, leaving the temperature profile inverted in excess of 10(6) K up into a corona without depositing wave or magnetic field energy into the gas above the base of the transition region as suggested to be possible in the previous paper (Scudder 1992a, hereafter Paper I); (2) that the temperature inversion process is essentially independent of magnetic topology working only slightly more efficiently on "closed" than on "open" flux tubes; (3) that the inversion temperature scale height can be extremely short for stars on the main sequence; (4) that there is an alternative suprathermal interpretation for the excess or "turbulent" Doppler widths by generalizing the Voigt-Hjerting line profile; (5) that the observed temperature dependence of the excess UV Doppler widths can be derived; (6) that a determination of a measure, kappa+(-1), of the ion nonthermal tail strength in the solar transition region of kappa+ = 2.2 +/- 0.8 implies a transition region temperature scale height of congruent-to 400 km, consistent with observations (for reference kappa = infinity is a Gaussian); (7) that a transition region/low coronal temperature profile from the inferred value of kappa simply produces solar coronal temperatures as a direct generalization of the exponential atmosphere; (8) that there is more than enough energy flux to sustain the solar corona against its known losses for 2.49 < kappa < 6.25; (9) that various correlations of heating with magnetic orientation and altitude in loops and sunspots follow as ready corollaries of this postulate; (10) that inversion temperatures in excess of 10(6) K for representative ZAMS stars are obtained, suggesting that they are capable of thermal X-ray emission as observed; (I 1) that the Parker critical point location in stellar radii is proportional to kappa and always above the stellar surface; (12) that the asymptotic wind speeds scale as U(infinity) congruent-to O(1)V(esc)/kappa1/2; (13) that U(infinity)(1 AU) at Earth is estimated to be between 300 and 600 km s-1, consistent with kappa-values in the range 2.4-7.1; (14) that values of kappa determined for different groups of stars based on the scaling of item (12) determine credible maximum inversion temperatures for these groups, including an explanation of why some classes of stars usually are not X-ray emitters; and (15) that a mechanism exists for "heating" solar wind minor ions proportionally to their mass. RP NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, MAIL CODE 692, GREENBELT, MD 20771 USA. RI Scudder, Jack/D-8417-2013 OI Scudder, Jack/0000-0001-7975-5630 NR 96 TC 139 Z9 139 U1 1 U2 6 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 OCT 10 PY 1992 VL 398 IS 1 BP 319 EP 349 DI 10.1086/171859 PN 1 PG 31 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ397 UT WOS:A1992JQ39700030 ER PT J AU COPPI, PS ZDZIARSKI, AA AF COPPI, PS ZDZIARSKI, AA TI NONTHERMAL ELECTRON-POSITRON PAIRS AND THE BREAK IN THE HARD X-RAY-SPECTRUM OF NGC-4151 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-4151); RADIATION MECHANISMS, COMPTON AND INVERSE COMPTON; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; COMPTON REFLECTION; COLD MATTER; VARIABILITY AB The recent observation by the detectors on board GRANAT of a spectral steepening above approximately 50 keV imposes a constraint on possible emission models for NGC 4151. This steepening, for example, is not well fitted by an exponential rollover characteristic of a purely thermal model, or by a Compton-downscattered power law. We find that this spectral behavior is consistent with that produced by a photon-starved nonthermal pair plasma with high compactness. This is the first quantitative test of the nonthermal pair plasma model against broad-band X-ray/gamma-ray observations. Above 200 keV or so, the nonthermal pair plasma model predicts an upturn in the spectrum, and a thermal annihilation feature around 511 keV. Such spectral behavior should be looked for with GRO. C1 JOHNS HOPKINS UNIV,BALTIMORE,MD 21218. NICHOLAS COPERNICUS ASTRON CTR,PL-00716 WARSAW,POLAND. MIT,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP COPPI, PS (reprint author), UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,5640 S ELLIS AVE,CHICAGO,IL 60637, USA. NR 31 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1992 VL 398 IS 1 BP L37 EP L40 DI 10.1086/186571 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ396 UT WOS:A1992JQ39600010 ER PT J AU GORSKI, KM AF GORSKI, KM TI DELTA-T/T LIMITS FROM THE UCSB SOUTH-POLE DEGREE-SCALE EXPERIMENT AND CONSTRAINTS ON THE LARGE-SCALE DEVIATIONS FROM THE HUBBLE FLOW SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY, COSMIC MICROWAVE BACKGROUND ID BACKGROUND FLUCTUATIONS; STREAMING MOTIONS; DARK MATTER; ANISOTROPIES; VELOCITY; UNIVERSE AB The limits to the cosmic microwave background radiation (CBR) temperature anisotropy derived from the results of the University of Califronia at Santa Barbara South Pole degree-scale experiment are translated into upper bounds on large-scale deviations from the Hubble flow. Calculations involve the Einstein-de Sitter, dark matter-dominated cosmology with standard thermal history (no early reheating) and gravitationally formed large-scale structure, seeded by random, Gaussian-distributed, adiabatic inhomogeneities. The results are independent of the Hubble constant, the composition of dark matter, and the power spectrum of primordial perturbations. The lack of measurable CBR anisotropy in this experiment implies very low upper bounds upon the rms amplitude V(R) of the streaming motion within a Gaussian window of radius R: V(max)(R > 4000 km s-1) < 200 km s-1, and V(max)(R > 7500 km s-1) < 100 km s-1. Thus, the smoothness of the CBR at theta approximately 1-degrees-2-degrees and the apparent large-amplitude (approximately 500 km s-1) deviations from pure Hubble flow at R greater than or similar to 4000 km s-1 cannot be simultaneously explained in the framework of usual large-scale structure formation models based on the assumptions involved in this calculation. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. CNRS,INST ASTROPHYS,F-75014 PARIS,FRANCE. RP GORSKI, KM (reprint author), UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,5640 S ELLIS AVE,CHICAGO,IL 60637, USA. NR 21 TC 18 Z9 18 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 OCT 10 PY 1992 VL 398 IS 1 BP L5 EP L8 DI 10.1086/186563 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ396 UT WOS:A1992JQ39600002 ER PT J AU FARR, TG AF FARR, TG TI MICROTOPOGRAPHIC EVOLUTION OF LAVA FLOWS AT CIMA VOLCANIC FIELD, MOJAVE DESERT, CALIFORNIA SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID SURFACE-ROUGHNESS; LANDSCAPE EVOLUTION; TOPOGRAPHY; IMAGES; TIME AB Microtopographic profiles were measured and power spectra calculated for dated lava flow surfaces at Cima volcanic field in the eastern Mojave Desert of California in order to quantify changes in centimeter- to meter-scale roughness as a function of age. For lava flows younger than about 0.8 m.y., roughness over all spatial scales decreases with age, with meter-scale roughness decreasing slightly more than centimeter scales. Flows older than about 0.8 m.y. show a reversal of this trend, becoming as rough as young flows at these scales. Modeling indicates that eolian deposition can explain most of the change observed in the offset, or roughness amplitude, of power spectra of flow surface profiles up to 0.8 m.y. Other processes, such as rubbling and stone pavement development, appear to have a minor effect in this age range. Changes in power spectra of surfaces older than about 0.8 m.y. are consistent with roughening . due to fluvial dissection. These results agree qualitatively with a process-response model that attributes systematic changes in flow surface morphology to cyclic changes in the rates of eolian, soil formation, and fluvial processes. Identification of active surficial processes and estimation of the extent of their effects, or stage of surficial evolution, through measurement of surface roughness will help put the correlation of surficial units on a quantitative basis. This may form the basis for the use of radar remote sensing data to help in regional correlations of surficial units. RP FARR, TG (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 47 TC 30 Z9 32 U1 2 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD OCT 10 PY 1992 VL 97 IS B11 BP 15171 EP 15179 DI 10.1029/92JB01592 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JR875 UT WOS:A1992JR87500007 ER PT J AU COHEN, SC AF COHEN, SC TI POSTSEISMIC DEFORMATION AND STRESS DIFFUSION DUE TO VISCOELASTICITY AND COMMENTS ON THE MODIFIED ELSASSER MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID EARTHQUAKE CYCLE; ASTHENOSPHERIC VISCOSITY; CRUSTAL DEFORMATION; DISLOCATION MODEL; SLIP EARTHQUAKES; JAPAN; RELAXATION AB Finite element techniques have been used to investigate the far-field deformation and stress changes due to asthenospheric viscoelastic relaxation following a dip-slip earthquake. The diffusion of extensional stress toward the subduction zone following a thrust earthquake on land is qualitatively consistent with the modified Elsasser model as proposed by Rydelek and Sacks (1988, 1990) to explain the coupled occurrence of land and sea earthquakes near Japan. However, the magnitude of the diffusing tensional signal is significantly smaller. The nominal model consists of a partially faulted elastic lithosphere overlying a viscoelastic substrate. Other models consider thin channel flow, rupturing of the entire elastic lithosphere, and changes in the depth of faulting. While some of these changes have significant impact on the magnitude and spatial features of the stress and deformation field, the far-field stress remains small. Numerical experiments demonstrate that the assumptions of the modified Elsasser model accentuate uniaxial deformation. When these assumptions are replicated in the finite element calculations, reasonable agreement between the models is achieved. RP COHEN, SC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. NR 20 TC 8 Z9 8 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-SOL EA JI J. Geophys. Res.-Solid Earth PD OCT 10 PY 1992 VL 97 IS B11 BP 15395 EP 15403 DI 10.1029/92JB01078 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JR875 UT WOS:A1992JR87500026 ER PT J AU MILLARD, RW LILLYWHITE, HB HARGENS, AR AF MILLARD, RW LILLYWHITE, HB HARGENS, AR TI CARDIOVASCULAR-SYSTEM DESIGN AND BAROSAURUS SO LANCET LA English DT Letter ID GIRAFFE C1 UNIV FLORIDA,DEPT ZOOL,GAINESVILLE,FL 32611. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. RP MILLARD, RW (reprint author), UNIV CINCINNATI,COLL MED,DEPT PHARMACOL & CELL BIOPHYS,CINCINNATI,OH 45267, USA. NR 9 TC 6 Z9 6 U1 0 U2 1 PU LANCET LTD PI LONDON PA 42 BEDFORD SQUARE, LONDON, ENGLAND WC1B 3SL SN 0140-6736 J9 LANCET JI Lancet PD OCT 10 PY 1992 VL 340 IS 8824 BP 914 EP 914 DI 10.1016/0140-6736(92)93326-I PG 1 WC Medicine, General & Internal SC General & Internal Medicine GA JT327 UT WOS:A1992JT32700038 PM 1357323 ER PT J AU FOOTE, MC JONES, BB HUNT, BD BARNER, JB VASQUEZ, RP BAJUK, LJ AF FOOTE, MC JONES, BB HUNT, BD BARNER, JB VASQUEZ, RP BAJUK, LJ TI COMPOSITION VARIATIONS IN PULSED-LASER-DEPOSITED Y-BA-CU-O THIN-FILMS AS A FUNCTION OF DEPOSITION PARAMETERS SO PHYSICA C LA English DT Article ID EVAPORATION TECHNIQUE; THEORETICAL-MODEL; YBA2CU3O7-X; ABLATION; GROWTH AB The composition of pulsed-ultraviolet-laser-deposited Y-Ba-Cu-O films was examined as a function of position across the substrate, laser fluence, laser spot size, substrate temperature, target conditioning, oxygen pressure and target-substrate distance. Laser fluence, laser spot size, and substrate temperature were found to have little effect on composition within the range investigated. Ablation from a fresh target surface results in films enriched in copper and barium, both of which decrease in concentration until a steady state condition is achieved. Oxygen pressure and target-substrate distance have a significant effect on film composition. In vacuum, copper and barium are slightly concentrated at the center of deposition. With the introduction of an oxygen background pressure, scattering results in copper and barium depletion in the deposition center, an effect which increases with increasing target-substrate distance. A balancing of these two effects results in stoichiometric deposition. RP FOOTE, MC (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 18 TC 51 Z9 51 U1 2 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4534 J9 PHYSICA C JI Physica C PD OCT 10 PY 1992 VL 201 IS 1-2 BP 176 EP 182 DI 10.1016/0921-4534(92)90121-R PG 7 WC Physics, Applied SC Physics GA JT407 UT WOS:A1992JT40700026 ER PT J AU PHILLIPS, RW AF PHILLIPS, RW TI SPACE STATION FREEDOM SO SCIENCE LA English DT Letter RP PHILLIPS, RW (reprint author), NASA,OFF SPACE SYST DEV,SPACE STN FREEDOM,WASHINGTON,DC 20546, USA. 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 OCT 9 PY 1992 VL 258 IS 5080 BP 204 EP 205 DI 10.1126/science.258.5080.204 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JR860 UT WOS:A1992JR86000004 PM 17835113 ER PT J AU ALLEN, D CRISP, D MEADOWS, V AF ALLEN, D CRISP, D MEADOWS, V TI VARIABLE OXYGEN AIRGLOW ON VENUS AS A PROBE OF ATMOSPHERIC DYNAMICS SO NATURE LA English DT Article ID NIGHT AIRGLOW; GENERAL-CIRCULATION; MESOSPHERE; THERMOSPHERE; EMISSION AB THE venusian atmosphere exhibits two global-scale circulation patterns: an east-west super-rotation at altitudes above 100 km and below 70 km, and a solar-locked circulation between these heights, in which material rises on the dayside of the planet, flows around to the nightside and descends near the antisolar point (local midnight). The region at which these two flows interact (approximately 95 km) is difficult to study, and existing data1 are either in conflict or indicate long-term dynamical changes. Here we present high-resolution images of an oxygen airglow that arises during down-welling at approximately 95 km altitude on the nightside of Venus. Oxygen atoms are formed by photolysis of CO2 on the sunlit hemisphere, and are then transported to the nightside, where they recombine during descent. The newly formed molecular oxygen emits radiation to produce the airglow. We observe localized, short-lived regions of emission and neighbouring dark areas, demonstrating the potential of such observations to constrain atmospheric dynamics at this little-studied and important altitude in the venusian mesosphere. C1 JET PROP LAB,PASADENA,CA 91109. UNIV SYDNEY,DEPT ASTROPHYS,SYDNEY,NSW 2006,AUSTRALIA. RP ALLEN, D (reprint author), ANGLO AUSTRALIAN OBSERV,POB 296,EPPING,NSW 2121,AUSTRALIA. NR 18 TC 31 Z9 31 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 OCT 8 PY 1992 VL 359 IS 6395 BP 516 EP 519 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JR859 UT WOS:A1992JR85900053 ER PT J AU LEE, TJ RICE, JE AF LEE, TJ RICE, JE TI PROTON AFFINITY OF METHYL NITRATE - LESS THAN PROTON AFFINITY OF NITRIC-ACID SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; GAS-PHASE; MOLECULAR CALCULATIONS; RELATIVE STABILITY; DIPOLE-MOMENT; 2 ISOMERS; ENERGIES; CONTRACTION AB The equilibrium structures, dipole moments, harmonic vibrational frequencies, and infrared intensities of methyl nitrate, methanol, and ten structures of protonated methyl nitrate have been investigated using state-of-the-art ab initio quantum mechanical methods. The ab initio methods include self-consistent field (SCF), second-order Moller-Plesset (MP2) perturbation theory, single- and double-excitation coupled-cluster (CCSD) theory, and the CCSD(T) method, which incorporates a perturbational estimate of the effects of connected triple excitations. The MP2 equilibrium geometry and vibrational frequencies of methyl nitrate and methanol are in good agreement with experiment. The lowest energy gas-phase form of protonated methyl nitrate is a complex between methanol and NO2+, although the next lowest isomer is only 4.9 kcal/mol higher in energy. The CH3OH...NO2+ complex is bound by 19.6 +/- 2 kcal/mol. The ab initio proton affinity (PA) of methyl nitrate is 176.9 +/- 5 kcal/mol, in very good agreement with the experimental value of 176 kcal/mol. The results of this study are contrasted with an earlier study on protonated nitric acid, and it is shown that methyl nitrate possesses a smaller PA than nitric acid. An explanation for this phenomenon is presented. C1 IBM CORP, ALMADEN RES CTR, DIV RES, SAN JOSE, CA 95120 USA. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Rice, Julia/K-4928-2012; Lee, Timothy/K-2838-2012 OI Rice, Julia/0000-0001-5059-5127; NR 47 TC 45 Z9 45 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD OCT 7 PY 1992 VL 114 IS 21 BP 8247 EP 8256 DI 10.1021/ja00047a040 PG 10 WC Chemistry, Multidisciplinary SC Chemistry GA JR863 UT WOS:A1992JR86300040 ER PT J AU KOSOWSKY, A TURNER, MS WATKINS, R AF KOSOWSKY, A TURNER, MS WATKINS, R TI GRAVITATIONAL-WAVES FROM 1ST-ORDER COSMOLOGICAL PHASE-TRANSITIONS SO PHYSICAL REVIEW LETTERS LA English DT Article ID FALSE VACUUM; RADIATION; FATE AB A first-order cosmological phase transition that proceeds through the nucleation and collision of true-vacuum bubbles is a potent source of gravitational radiation. Possibilities for such include first-order inflation, grand-unified-theory-symmetry breaking, and electroweak-symmetry breaking. We have calculated gravity-wave production from the collision of two scalar-field vacuum bubbles, and, using an approximation based upon these results, from the collision of 20 to 30 vacuum bubbles. We present estimates of the relic background of gravitational waves produced by a first-order phase transition; in general, OMEGA(GW) is similar to 10(-9) and f is similar to (10(-6) Hz)(T/1 GeV). C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP KOSOWSKY, A (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510, USA. NR 18 TC 107 Z9 107 U1 2 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 OCT 5 PY 1992 VL 69 IS 14 BP 2026 EP 2029 DI 10.1103/PhysRevLett.69.2026 PG 4 WC Physics, Multidisciplinary SC Physics GA JQ622 UT WOS:A1992JQ62200002 ER PT J AU LAU, YT AF LAU, YT TI LARGE-PERIOD TURBULENT SOLUTIONS OF THE KURAMOTO-SIVASHINSKY EQUATION SO PHYSICS LETTERS A LA English DT Article ID TRAVELING-WAVE SOLUTIONS; LIQUID-FILM SURFACES; NON-LINEAR ANALYSIS; TRAPPED-ION MODE; HYDRODYNAMIC INSTABILITY; NONLINEAR SATURATION; INERTIAL MANIFOLDS; LAMINAR FLAMES; FLUID; PROPAGATION AB We solve numerically the Kuramoto-Sivashinsky equation for large period l. In the limit l --> infinity, we show that the solution is associated with a three-dimensional dynamical system, whose control parameter E takes a unique value E*. We give evidence that E* lies in a stationary point within a structurally stable window of the parameter space of the associated dynamical system. Furthermore, we introduce the flux exponent gamma, which characterizes the global stretching property of a dynamical system. We compute gamma for the associated dynamical system with different values of E. Our numerical results and heuristic arguments suggest that, in the limit of large l, the most probable state of the Kuramoto-Sivashinsky equation occurs at the point of maximal gamma, which corresponds to the value E* of the associated dynamical system. This conjecture links the Kuramoto-Sivashinsky equation, which is equivalent to an infinite-dimensional dynamical system, to a three-dimensional dynamical system. RP LAU, YT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NATL RES COUNCIL,MAIL CODE 9301,GREENBELT,MD 20771, USA. NR 42 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0375-9601 J9 PHYS LETT A JI Phys. Lett. A PD OCT 5 PY 1992 VL 169 IS 5 BP 329 EP 334 DI 10.1016/0375-9601(92)90236-F PG 6 WC Physics, Multidisciplinary SC Physics GA JR700 UT WOS:A1992JR70000003 ER PT J AU MURTHY, DV JANETZKE, DC AF MURTHY, DV JANETZKE, DC TI CONCURRENT PROCESSING ADAPTATION OF AEROELASTIC ANALYSIS OF PROPFANS SO COMPUTERS & STRUCTURES LA English DT Article AB This paper reports on a study involving the adaptation of an advanced aeroelastic analysis program to run concurrently on a shared memory multiple processor computer. The program uses a three-dimensional compressible unsteady aerodynamic model and blade normal modes to calculate aeroelastic stability and response of propfan blades. The identification of the computational parallelism within the sequential code and the scheduling of the concurrent subtasks to minimize processor idle time are discussed. Processor idle time in the calculation of the unsteady aerodynamic coefficients was reduced by the simple strategy of appropriately ordering the computations. Speedup and efficiency results are presented for the calculation of the matched flutter point of an experimental propfan model. The results show that efficiencies above 70% can be obtained using the present implementation with seven procesors The parallel computational strategy described here is also applicable to other aeroelastic analysis procedures based on panel methods. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 9 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD OCT 3 PY 1992 VL 45 IS 2 BP 397 EP 404 DI 10.1016/0045-7949(92)90423-W PG 8 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA JV637 UT WOS:A1992JV63700019 ER PT J AU SIBECK, DG SMITH, MF AF SIBECK, DG SMITH, MF TI MAGNETOSPHERIC PLASMA FLOWS ASSOCIATED WITH BOUNDARY WAVES AND FLUX-TRANSFER EVENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DAYSIDE MAGNETOPAUSE AB We describe plasma flow perturbations in the outer magnetosphere during the passage of magnetopause boundary waves and cylindrically shaped flux transfer events (FTEs). Spacecraft which remain within the magnetosphere observe bipolar flows normal to the nominal magnetopause accompanied by flows nearly opposite to the direction of boundary wave and/or FTE motion. Flows are generally discontinuous across FTE and magnetopause boundaries, with reversals in the component of flow tangential to the nominal magnetopause expected during all magnetopause crossings and some entries into FTEs. No bipolar flows normal to the nominal magnetopause occur within FTEs unless they rotate and none occur in the magnetosheath unless the boundary waves propagate relative to the magnetosheath flow. IRM satellite observations on October 28, 1984 may be interpreted either in terms of FTEs or boundary waves. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP SIBECK, DG (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20707, USA. RI Sibeck, David/D-4424-2012 NR 14 TC 32 Z9 32 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 OCT 2 PY 1992 VL 19 IS 19 BP 1903 EP 1906 DI 10.1029/92GL01614 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JR219 UT WOS:A1992JR21900002 ER PT J AU SMITH, MF OWEN, CJ AF SMITH, MF OWEN, CJ TI TEMPERATURE ANISOTROPIES IN A MAGNETOSPHERIC FTE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FLUX-TRANSFER EVENTS; PLASMA DEPLETION LAYER; DAYSIDE MAGNETOPAUSE; EARTHS MAGNETOPAUSE; ION; MAGNETOSHEATH; MAGNETOMETER; DISTRIBUTIONS; RECONNECTION; BOUNDARY AB We present AMPTE UKS data from a well-studied magnetospheric flux transfer event, showing detailed ion phase-space distributions for each region of this layered event. We show that the perpendicular temperature anisotropy maximizes at the center of the event. This is inconsistent with recent suggestions that FTE signatures may result from the spacecraft moving into and then out of the magnetosheath via the plasma depletion layer. We present an explanation for the temperature anisotropy structure in terms of a reconnection model. RP SMITH, MF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. RI Owen, Christopher/C-2999-2008 OI Owen, Christopher/0000-0002-5982-4667 NR 23 TC 27 Z9 27 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 OCT 2 PY 1992 VL 19 IS 19 BP 1907 EP 1910 DI 10.1029/92GL01618 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JR219 UT WOS:A1992JR21900003 ER PT J AU KINNE, S TOON, OB PRATHER, MJ AF KINNE, S TOON, OB PRATHER, MJ TI BUFFERING OF STRATOSPHERIC CIRCULATION BY CHANGING AMOUNTS OF TROPICAL OZONE - A PINATUBO CASE-STUDY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EL-CHICHON; MASS AB Stratospheric aerosol from Mount Pinatubo heated the tropical lower stratosphere by about 0.3 K/day mainly due to absorption of terrestrial infrared radiation. This heating was dissipated by (1) an observed increase in stratospheric temperatures, which enhanced the radiative cooling, (2) additional mean upward motion, observed for the aerosol cloud, which led to adiabatic cooling and (3) reductions in ozone concentrations resulting from enhanced upward motions. Each of these processes operated on a different time scale: maximum temperatures were observed after about 90 days; maximum ozone losses of about -1.5 ppm occurred after 140 days when the enhanced vertical velocities effectively lifted the ozone profile by about 2 km. We believe this shows that ozone plays an important role in buffering vertical motion in the tropical lower stratosphere, and hence the residual Brewer Dobson circulation of the whole stratosphere. C1 UNIV CALIF IRVINE,DEPT GEOSCI,IRVINE,CA 92717. RP KINNE, S (reprint author), NASA,AMES RES CTR,MS 245-4,MOFFETT FIELD,CA 94035, USA. NR 12 TC 100 Z9 100 U1 0 U2 4 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 OCT 2 PY 1992 VL 19 IS 19 BP 1927 EP 1930 DI 10.1029/92GL01937 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JR219 UT WOS:A1992JR21900008 ER PT J AU STACHNIK, RA HARDY, JC TARSALA, JA WATERS, JW ERICKSON, NR AF STACHNIK, RA HARDY, JC TARSALA, JA WATERS, JW ERICKSON, NR TI SUBMILLIMETER WAVE HETERODYNE MEASUREMENTS OF STRATOSPHERIC CLO, HCL, O3, AND HO2 - 1ST RESULTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INSITU MEASUREMENTS; CONCENTRATION PROFILES; OH AB The vertical profiles of ClO, HCl, HO2 and O3 were determined from thermal emission measurements by a balloon-borne spectrometer operating near 640 GHz. Results are in broad agreement with previous measurements and models, but differ significantly with model photochemistry for the ratio of ClO to HCl. C1 MILLITECH CORP,S DEERFIELD,MA 01373. RP STACHNIK, RA (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 75 Z9 75 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 OCT 2 PY 1992 VL 19 IS 19 BP 1931 EP 1934 DI 10.1029/92GL01884 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JR219 UT WOS:A1992JR21900009 ER PT J AU TSURUTANI, BT GONZALEZ, WD TANG, F LEE, YT OKADA, M PARK, D AF TSURUTANI, BT GONZALEZ, WD TANG, F LEE, YT OKADA, M PARK, D TI SOLAR-WIND RAM PRESSURE CORRECTIONS AND AN ESTIMATION OF THE EFFICIENCY OF VISCOUS INTERACTION - REPLY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Note ID MAGNETIC STORMS C1 INST NACL PESQUISAS ESPACIAIS,SAO JOSE CAMPOS,SP,BRAZIL. CALTECH,PASADENA,CA 91125. KYOTO UNIV,UJI,KYOTO 611,JAPAN. LOCKHEED AIRCRAFT SERV CO,ONTARIO,CA 91761. UNIV CALIF IRVINE,IRVINE,CA 92717. RP TSURUTANI, BT (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 12 TC 32 Z9 32 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 OCT 2 PY 1992 VL 19 IS 19 BP 1993 EP 1994 DI 10.1029/92GL02239 PG 2 WC Geosciences, Multidisciplinary SC Geology GA JR219 UT WOS:A1992JR21900025 ER PT J AU BEARD, JS LOFGREN, GE AF BEARD, JS LOFGREN, GE TI AN EXPERIMENT-BASED MODEL FOR THE PETROGENESIS OF HIGH-ALUMINA BASALTS SO SCIENCE LA English DT Article ID PHASE-RELATIONS; ISLAND-ARC; ORIGIN; VOLCANO AB To understand magmatism at convergent margins, one must know the origin of their characteristic, plagioclase-rich, high-alumina basalts (HABs). Wet melting experiments on basalts at 3 kilobars yielded high-alumina liquids and a coexisting mineral assemblage with little or no plagioclase. An isothermal pressure drop to 1 kilobar caused 20 to 30 percent plagioclase crystallization in these melts, while mafic minerals underwent limited crystallization or even resorption. These results suggest that hydrous (greater-than-or-equal-to 4 percent H2O) HAB liquids, presumably formed by fractionation of a hydrous basalt at depth, will precipitate voluminous plagioclase as pressure drops during ascent and eruption. Plagioclase accumulation is not necessarily required to explain the petrogenesis of plagioclase-rich HAB. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP BEARD, JS (reprint author), VIRGINIA MUSEUM NAT HIST,MARTINSVILLE,VA 24112, USA. NR 26 TC 9 Z9 9 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 2 PY 1992 VL 258 IS 5079 BP 112 EP 115 DI 10.1126/science.258.5079.112 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JQ619 UT WOS:A1992JQ61900029 PM 17835894 ER PT J AU BUSHNELL, DM AF BUSHNELL, DM TI THE 32ND LANCHESTER LECTURE - LONGITUDINAL VORTEX CONTROL - TECHNIQUES AND APPLICATIONS SO AERONAUTICAL JOURNAL LA English DT Article AB Longitudinal vortices have tremendous practical utility for flow control (control by vortices) and in some cases have exhibited tremendous potential for causing harm if uncontrolled (i.e. control of vortices is required). Vortex control has thus far been carried out via multitudinous approaches in an empirical fashion, aided by the essentially inviscid nature of much of longitudinal vortex behaviour. Further refinement and several applications of vortex flow control require knowledge regarding the detailed flow physics of longitudinal vortices such as transition. transitional flow regimes, turbulence structure and modelling, and interaction with shock waves, other vortices and surfaces. This paper summarises vortex control applications and extant techniques for the control of longitudinal vortices produced by bodies, leading edges. tips, and intersections. RP BUSHNELL, DM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 9 Z9 9 U1 0 U2 1 PU ROYAL AERONAUTICAL SOC PI LONDON PA 4 HAMILTON PL, LONDON, ENGLAND W1V OBQ SN 0001-9240 J9 AERONAUT J JI Aeronaut. J. PD OCT PY 1992 VL 96 IS 958 BP 293 EP 312 PG 20 WC Engineering, Aerospace SC Engineering GA KA212 UT WOS:A1992KA21200001 ER PT J AU VIEGAS, JR RUBESIN, MW AF VIEGAS, JR RUBESIN, MW TI ASSESSMENT OF COMPRESSIBILITY CORRECTIONS TO THE K-EPSILON MODEL IN HIGH-SPEED SHEAR LAYERS SO AIAA JOURNAL LA English DT Article ID MIXING LAYERS AB TWO compressibility corrections to the standard k-epsilon turbulence model are used with the Navier-Stokes equations to compute the mixing region between two streams of the same gas flowing under a variety of low- and high-speed freestream conditions. The model corrections are assessed by comparing 1) computed spread rates for a series of unconfined flows with data for a range of convective Mach numbers, and 2) velocity profiles for a confined flow. RP VIEGAS, JR (reprint author), NASA,MOFFETT FIELD,CA 94035, USA. NR 12 TC 8 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1992 VL 30 IS 10 BP 2369 EP 2370 DI 10.2514/3.11235 PG 2 WC Engineering, Aerospace SC Engineering GA JR887 UT WOS:A1992JR88700001 ER PT J AU SRINIVASAN, GR BAEDER, JD OBAYASHI, S MCCROSKEY, WJ AF SRINIVASAN, GR BAEDER, JD OBAYASHI, S MCCROSKEY, WJ TI FLOWFIELD OF A LIFTING ROTOR IN HOVER - A NAVIER-STOKES SIMULATION SO AIAA JOURNAL LA English DT Article ID EULER EQUATIONS; FINITE-DIFFERENCE; HELICOPTER ROTOR; FLOW; SCHEMES AB The viscous, three-dimensional flowfield of a helicopter rotor in hover is calculated by using an implicit, upwind, finite difference numerical method for the solution of thin-layer Navier-Stokes equations. The induced effects of the wake, including the interaction of tip vortices with successive blades, are calculated as a part of the overall flowfield solution without specifying any wake models. Comparison of the numerical results at subsonic and transonic flow conditions show good agreement with the experimental data for the surface pressures and the nearfield vortex trajectory. However, the captured vortex structure is diffused due to the coarse grids, but this appears to have minimal influence on the prediction of surface pressures. The paper also presents limited comparisons of the Navier-Stokes results with Euler results along with some discussion on grid refinement studies. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 36 TC 74 Z9 82 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 OCT PY 1992 VL 30 IS 10 BP 2371 EP 2378 DI 10.2514/3.11236 PG 8 WC Engineering, Aerospace SC Engineering GA JR887 UT WOS:A1992JR88700002 ER PT J AU YUNGSTER, S AF YUNGSTER, S TI NUMERICAL STUDY OF SHOCK-WAVE BOUNDARY-LAYER INTERACTIONS IN PREMIXED COMBUSTIBLE GASES SO AIAA JOURNAL LA English DT Article ID NAVIER-STOKES EQUATIONS; RAM ACCELERATOR; PROJECTILES; SCHEMES AB A computational study of shock-wave/boundary-layer interactions involving premixed combustible gases is presented. The analysis is carried out using a new fully implicit, total variation diminishing code that solves the fully coupled Reynolds-averaged Navier-Stokes equations and species continuity equations in an efficient manner. To accelerate the convergence of the basic iterative procedure, the code is combined with vector extrapolation methods. The chemical nonequilibrium processes are simulated by means of a finite-rate chemistry model for hydrogen-air combustion. The investigation is conducted on a ramjet-in-tube projectile accelerator concept known as the "ram accelerator." Results indicate a combustion mechanism in which a shock wave induces combustion in the boundary layer, which then couples with the reflected shock, forming a shock-deflagration wave. At higher Mach numbers, spontaneous combustion in part of the boundary layer is observed, which eventually extends along the entire boundary layer at still higher values of the Mach number. RP YUNGSTER, S (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 29 TC 25 Z9 25 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 OCT PY 1992 VL 30 IS 10 BP 2379 EP 2387 DI 10.2514/3.11237 PG 9 WC Engineering, Aerospace SC Engineering GA JR887 UT WOS:A1992JR88700003 ER PT J AU WILMOTH, RG AF WILMOTH, RG TI APPLICATION OF A PARALLEL DIRECT SIMULATION MONTE-CARLO METHOD TO HYPERSONIC RAREFIED FLOWS SO AIAA JOURNAL LA English DT Article AB Application of a method for performing direct simulation Monte Carlo calculations using parallel processing to several hypersonic, rarefied flow problems is presented. The performance and efficiency of the parallel method are discussed in terms of some simple benchmark problems. The applications described are the now in a channel and the flow about a flat plate at incidence. The benchmark results show significant advantages of parallel processing over conventional scalar processing and demonstrate the scalability of the method to large problems. The applications to hypersonic rarefied flows demonstrate the capabilities of the method, and the results demonstrate the need to adapt the parallel decomposition to the flowfield in order to achieve good load balancing. RP WILMOTH, RG (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 11 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 OCT PY 1992 VL 30 IS 10 BP 2447 EP 2452 DI 10.2514/3.11246 PG 6 WC Engineering, Aerospace SC Engineering GA JR887 UT WOS:A1992JR88700012 ER PT J AU BOYD, ID PENKO, PF MEISSNER, DL DEWITT, KJ AF BOYD, ID PENKO, PF MEISSNER, DL DEWITT, KJ TI EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF LOW-DENSITY NOZZLE AND PLUME FLOWS OF NITROGEN SO AIAA JOURNAL LA English DT Article ID NONEQUILIBRIUM AB Experimental and numerical investigations are performed and compared for the now of nitrogen in a small nozzle and in the near field of the plume resulting from expansion into near-vacuum conditions. The experimental data obtained were in the form of pressure measurements using a pitot tube, in the nozzle-exit plane and near field of the plume. Since the flow regimes vary from continuum, at the nozzle throat, to rarefied, in the plume, two different numerical studies are undertaken: the first employs a continuum approach in solving the Navier-Stokes equations, and the second employs a stochastic particle approach through the use of the direct simulation Monte Carlo (DSMC) method. Comparison of the experimental data and the numerical results at the nozzle exit reveals that the DSMC technique provides the more accurate description of the expanding flow. It is discovered that the DSMC solutions are quite sensitive to the model employed to simulate the interaction between the gas and the nozzle-wall surface. It is concluded that the simple fully diffuse model is quite satisfactory for the present application. The study provides the strongest evidence to date that the DSMC technique predicts accurately the now characteristics of low-density expanding flows. C1 ELORET INST,PALO ALTO,CA 94303. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. UNIV TOLEDO,TOLEDO,OH 43606. NR 22 TC 51 Z9 66 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 OCT PY 1992 VL 30 IS 10 BP 2453 EP 2461 DI 10.2514/3.11247 PG 9 WC Engineering, Aerospace SC Engineering GA JR887 UT WOS:A1992JR88700013 ER PT J AU PIERRE, C MURTHY, DV AF PIERRE, C MURTHY, DV TI AEROELASTIC MODAL CHARACTERISTICS OF MISTUNED BLADE ASSEMBLIES - MODE LOCALIZATION AND LOSS OF EIGENSTRUCTURE SO AIAA JOURNAL LA English DT Article ID FLUTTER; CASCADE; ROTORS AB An investigation of the effects of small mistuning on the aeroelastic modes of bladed-disk assemblies with aerodynamic coupling between blades is presented. The cornerstone of the approach is the use and development of perturbation methods that exhibit the crucial role of the interblade coupling and yield general findings regarding mistuning effects. It is shown that blade assemblies with weak aerodynamic interblade coupling are highly sensitive to small blade mistuning and that their dynamics are qualitatively altered in the following ways: the regular pattern that characterizes the root locus of the tuned aeroelastic eigenvalues in the complex plane is totally lost; the aeroelastic mode shapes become severely localized to only a few blades of the assembly and lose their constant interblade phase angle feature; curve veering phenomena take place when the eigenvalues are plotted vs a mistuning parameter. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP PIERRE, C (reprint author), UNIV MICHIGAN,ANN ARBOR,MI 48109, USA. NR 17 TC 32 Z9 36 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 OCT PY 1992 VL 30 IS 10 BP 2483 EP 2496 DI 10.2514/3.11251 PG 14 WC Engineering, Aerospace SC Engineering GA JR887 UT WOS:A1992JR88700017 ER PT J AU GURUSWAMY, GP AF GURUSWAMY, GP TI VORTICAL FLOW COMPUTATIONS ON A FLEXIBLE BLENDED WING-BODY CONFIGURATION SO AIAA JOURNAL LA English DT Article ID ALGORITHM; FORM AB Flows over blended wing-body configurations are often dominated by vortices. The unsteady aerodynamic forces due to such flows can couple with the elastic forces of the wing and lead to aeroelastic oscillations. Such aeroelastic oscillations can impair the performance of an aircraft. To study this phenomenon, it is necessary to account for structural properties of the configuration, and solve the aerodynamic and aeroelastic equations of motion simultaneously. In this work, the flow is modeled using the Navier-Stokes equations coupled with the aeroelastic equations of motion. Computations are made for a blended wing-body configuration at now conditions dominated by vortices and separation. The computed results are validated with the available experimental data. Almost sustained aeroelastic oscillations observed in the wind tunnel are successfully simulated for M(infinity) = 0.975, alpha almost-equal-to 8.0 deg, and a frequency of about 2 Hz. RP GURUSWAMY, GP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 15 TC 9 Z9 9 U1 1 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 OCT PY 1992 VL 30 IS 10 BP 2497 EP 2503 DI 10.2514/3.11252 PG 7 WC Engineering, Aerospace SC Engineering GA JR887 UT WOS:A1992JR88700018 ER PT J AU JACOBS, PA AF JACOBS, PA TI APPROXIMATE RIEMANN SOLVER FOR HYPERVELOCITY FLOWS SO AIAA JOURNAL LA English DT Note ID DIFFERENCE-SCHEMES RP JACOBS, PA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 13 TC 8 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1992 VL 30 IS 10 BP 2558 EP 2561 DI 10.2514/3.11264 PG 4 WC Engineering, Aerospace SC Engineering GA JR887 UT WOS:A1992JR88700030 ER PT J AU HUNLEY, JD AF HUNLEY, JD TI THE BOURGEOIS EPOCH - MARX AND ENGELS ON BRITAIN, FRANCE, AND GERMANY - HAMILTON,RF SO AMERICAN HISTORICAL REVIEW LA English DT Book Review RP HUNLEY, JD (reprint author), NASA,DIV HIST,WASHINGTON,DC 20546, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER HISTORICAL REVIEW PI WASHINGTON PA 400 A ST SE, WASHINGTON, DC 20003 SN 0002-8762 J9 AM HIST REV JI Am. Hist. Rev. PD OCT PY 1992 VL 97 IS 4 BP 1206 EP 1207 DI 10.2307/2165557 PG 2 WC History SC History GA JV069 UT WOS:A1992JV06900053 ER PT J AU BROOKS, VL KEIL, LC AF BROOKS, VL KEIL, LC TI VASOPRESSIN AND ANGIOTENSIN-II IN REFLEX REGULATION OF ACTH, GLUCOCORTICOIDS, AND RENIN - EFFECT OF WATER-DEPRIVATION SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE V-1-VASOPRESSIN ANTAGONIST; V-1/V-2-VASOPRESSIN ANTAGONIST; SARALASIN; RENIN-ANGIOTENSIN SYSTEM; BLOOD PRESSURE; NITROPRUSSIDE; BARORECEPTOR REFLEX; CONSCIOUS DOGS; ADRENOCORTICOTROPIC HORMONE ID NEUROHYPOPHYSECTOMIZED CONSCIOUS DOGS; RAT ADRENAL-GLAND; ADRENOCORTICOTROPIN SECRETION; ANTIDIURETIC ACTIVITY; BLOCKADE; SYSTEM; VASOCONSTRICTOR; OXYTOCIN; RELEASE; STRESS AB Angiotensin II (ANG II) and vasopressin participate in baroreflex regulation of adrenocorticotropic hormone (ACTH), glucocorticoid, and renin secretion. The purpose of this study was to determine whether this participation is enhanced in water-deprived dogs, with chronically elevated plasma ANG II and vasopressin levels, compared with water-replete dogs. The baroreflex was assessed by infusing increasing doses of nitroprusside (0.3, 0.6, 1.5, and 3.0 mug.kg-1.min-1) in both groups of animals. To quantitate the participation of ANG II and vasopressin, the dogs were untreated or pretreated with the competitive ANG II antagonist saralasin, a V1-vasopressin antagonist, or combined V1/V2-vasopressin antagonist, either alone or in combination. The findings were as follows. 1) Larger reflex increases in ANG II, vasopressin, and glucocorticoids, but not ACTH, were produced in water-deprived dogs compared with water-replete dogs. 2) ANG II blockade blunted the glucocorticoid and ACTH responses to hypotension in water-deprived dogs, but not water-replete dogs. In contrast, vasopressin blockade reduced the ACTH response only in water-replete dogs. 3) Vasopressin or combined vasopressin and ANG II blockade reduced the plasma level of glucocorticoids related either to the fall in arterial pressure or to the increase in plasma ACTH concentration in water-replete dogs, and this effect was enhanced in water-deprived dogs. 4) In both water-deprived and water-replete animals, saralasin and/or a V1-antagonist increased the renin response to hypotension, but a combined V1/V2-antagonist did not. These results reemphasize the importance of endogenous ANG II and vasopressin in the regulation of ACTH, glucocorticoid, and renin secretion. Moreover, although the results do not support an enhanced role of vasopressin in the regulation of ACTH secretion during water deprivation, the participation of ANG II or vasopressin in the regulation of glucocorticoid production may increase. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BROOKS, VL (reprint author), OREGON HLTH SCI UNIV,DEPT PHYSIOL,L-334,3181 SW SAM JACKSON PK RD,PORTLAND,OR 97201, USA. FU NHLBI NIH HHS [HL-35872, HL-39923] NR 31 TC 11 Z9 11 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 OCT PY 1992 VL 263 IS 4 BP R762 EP R769 PN 2 PG 8 WC Physiology SC Physiology GA JU806 UT WOS:A1992JU80600050 PM 1329565 ER PT J AU CHAN, WM STEGER, JL AF CHAN, WM STEGER, JL TI ENHANCEMENTS OF A 3-DIMENSIONAL HYPERBOLIC GRID GENERATION SCHEME SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article AB A hyperbolic grid generation scheme formulated from grid orthogonality and cell volume specification has been significantly enhanced so that high quality three-dimensional grids can be obtained for a wide variety of geometries. While the speed of the scheme remains one to two orders of magnitude faster than typical elliptic grid generation methods, the robustness of the scheme has been greatly improved over previous applications of the three-dimensional hyperbolic grid generation procedure. Enhancements included the use of spatially-variable smoothing coefficient, metric correction procedures, local treatment of severe convex comers, and new extrapolation treatments of floating and axis boundaries. The versatility of the new hyperbolic grid generation scheme is demonstrated by three-dimensional grids generated for external components of the integrated Space Shuttle vehicle and the SOFIA telescope. C1 UNIV CALIF DAVIS,DEPT MECH AERONAUT & MAT ENGN,DAVIS,CA 95616. RP CHAN, WM (reprint author), NASA,AMES RES CTR,MCAT INST,MAIL STOP T045-2,MOFFETT FIELD,CA 94035, USA. NR 16 TC 34 Z9 36 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD OCT PY 1992 VL 51 IS 2-3 BP 181 EP 205 DI 10.1016/0096-3003(92)90073-A PG 25 WC Mathematics, Applied SC Mathematics GA JP405 UT WOS:A1992JP40500008 ER PT J AU ODEA, CP BAUM, SA STANGHELLINI, C DEY, A VANBREUGEL, W DEUSTUA, S SMITH, EP AF ODEA, CP BAUM, SA STANGHELLINI, C DEY, A VANBREUGEL, W DEUSTUA, S SMITH, EP TI RADIO AND OPTICAL OBSERVATIONS OF 0218+357 - THE SMALLEST EINSTEIN RING SO ASTRONOMICAL JOURNAL LA English DT Article ID GALACTIC MAGNETIC-FIELD; SMALL-SCALE VARIATIONS; SURFACE PHOTOMETRY; ROTATION MEASURES; VLA OBSERVATIONS; FARADAY-ROTATION; COMPLETE SAMPLE; STAR FORMATION; GALAXIES; IMAGE AB We present VLA3 radio observations and optical imaging and spectroscopy of 0218 + 357, which has been suggested to be the smallest known Einstein radio ring by Patnaik et al. (1991), preprint. The optical spectrum is rather red (F(nu) is-proportional-to nu(alpha), alpha approximately - 3.5) and shows no strong features. We have a tentative detection of the 4000 angstrom break and the G band which give a redshift of z congruent-to 0.68. The identification is a m(r) congruent-to 20 resolved galaxy, with an absolute magnitude of M(R) approximately - 23.8 or M(B) approximately - 22.0 which is consistent with the radio galaxy host being a brightest cluster member. The ring is detected for the first time at 22.4 GHz, and has basically similar structure at 5, 15, and 22.4 GHz. The ring is highly polarized at 8.4 GHz. Component B has varied in the radio and was approximately 15% brighter in our data than in Patnaik et al.'s. There is very powerful (P1.4 approximately 10(26) W Hz-1) amorphous radio structure extending out to approximately 11" (approximately 70 kpc) from the core. By analogy with previous analyses of Einstein radio rings we suggest that the observed double core and ring structure may be produced by a combination of an off-center radio core with extended radio structure (a jet?) which crosses behind the center of the lensing galaxy. Based on the small angular size of the ring, we estimate a small value for the central radial velocity dispersion of the lens sigma approximately 110 km s-1 which leads to a rather faint absolute magnitude (MB(T)0 approximately - 17.4 for an elliptical via the Faber-Jackson relationship or MB(T)0 approximately - 19.1 for a spiral via the Tully-Fisher relationship). The high value of the observed RM and the difference in RM between A and B may require unusual parameters for the interstellar medium (ISM) of the lens. This is one of the remaining puzzles in the object. In summary, the radio source shares some of the optical and radio properties of BL Lac objects and compact double radio sources and we cannot currently rule out the possibility that the source is not lensed. However, based on the core and ring properties we suggest that the object may well be lensed. In this case, the lensed object is most likely a powerful radio source (a BL Lac object or a Fanaroff-Riley Class I edge-darkened radio galaxy) at a redshift of 0.68, and the lens is a faint, low mass object at an intervening redshift. The small angular scale of the lensed image implies that very small scale structure in the radio source is being lensed. Proper motions in the radio "jet" may be magnified and may be visible as changes in the structure of the Einstein ring. C1 UNIV BOLOGNA,DIPARTIMENTO ASTRON,I-40100 BOLOGNA,ITALY. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94550. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. CNR,IST RADIOASTRON,I-40126 BOLOGNA,ITALY. RP ODEA, CP (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. OI Stanghellini, Carlo/0000-0002-6415-854X NR 76 TC 66 Z9 66 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 OCT PY 1992 VL 104 IS 4 BP 1320 EP 1330 DI 10.1086/116321 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JP900 UT WOS:A1992JP90000005 ER PT J AU STEIMANCAMERON, TY KORMENDY, J DURISEN, RH AF STEIMANCAMERON, TY KORMENDY, J DURISEN, RH TI THE REMARKABLE TWISTED DISK OF NGC 4753 AND THE SHAPES OF GALACTIC HALOS SO ASTRONOMICAL JOURNAL LA English DT Article ID PREFERRED ORBIT PLANES; TRIAXIAL GALAXIES; GAS DISKS; POLAR RINGS; S0 GALAXIES; EVOLUTION; PROLATE; MODELS; WARPS AB The complex dust lanes in the SO galaxy NGC 4753 are shown to be consistent with a disk that is strongly twisted by differential precession. Yet another peculiar SO can therefore be explained as the result of an accretion event. An evolving disk model is fitted to the observed dust distribution. This disk is inclined by 15-degrees relative to the galaxy's equatorial plane and twisted such that its line of nodes changes smoothly by 3.8pi over a factor of seven in radius. The model shows excellent agreement between increased line-of-sight path lengths through the disk and the observed dust lanes. A nodal precession rate proportional to r-1 matches the observations with considerable accuracy. The model indicates that most of the galaxy's mass is unseen, is nearly spherically distributed, and has a nearly scale-free spatial distribution. The ellipticity of the total galactic mass distribution must be constant to within 20% over the radial extent of the twisted disk-a conclusion which may significantly constrain galaxy formation mechanisms. If the disk and the main body of NGC 4753 rotate in the same direction, then the sense of the twist implies an oblate galactic mass distribution. The flattening of the halo and the age of the accretion event cannot be determined independently, but physical arguments imply that the shape of the total mass distribution is between approximately E0.1 and E1.6. C1 UNIV CALIF SANTA CRUZ, LICK OBSERV, SANTA CRUZ, CA 95064 USA. UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. INDIANA UNIV, DEPT ASTRON, BLOOMINGTON, IN 47405 USA. MAX PLANCK INST EXTRATERRESTR PHYS, GARCHING, GERMANY. RP NASA, AMES RES CTR, THEORET STUDIES BRANCH, MS 245-3, MOFFETT FIELD, CA 94035 USA. NR 40 TC 53 Z9 53 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 OCT PY 1992 VL 104 IS 4 BP 1339 EP 1348 DI 10.1086/116323 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JP900 UT WOS:A1992JP90000007 ER PT J AU TOKUNAGA, AT HANNER, MS GOLISCH, WF GRIEP, DM KAMINSKI, CD CHEN, H AF TOKUNAGA, AT HANNER, MS GOLISCH, WF GRIEP, DM KAMINSKI, CD CHEN, H TI INFRARED MONITORING OF COMET P/TEMPEL 2 SO ASTRONOMICAL JOURNAL LA English DT Article ID P/AREND-RIGAUX; P TEMPEL-2; NUCLEUS; DUST; PHOTOMETRY; HALLEY; ROTATION; PROGRAM; IMAGES; MODEL AB Observations of P/Tempel 2 at 1.25-20.0 mum during its 1983 and 1988 apparitions are presented. The thermal emission from the nucleus was monitored, and the dust production rate during the 1988 apparition is estimated. We find that the nucleus can contribute up to 40% of the total 10 mum flux even near perihelion and that P/Tempel 2 has a dust production rate that is typical of short-period comets. The J - H color of the nucleus, 0.65 +/- 0.05, is the reddest of any observed so far. The geometric albedo of the nucleus at 1.25-2.20 mum was found to be 0.04-0.07. C1 JET PROP LAB,PASADENA,CA 91109. NASA,INFRARED TELESCOPE FACIL,HILO,HI 96720. RP TOKUNAGA, AT (reprint author), UNIV HAWAII,INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. NR 35 TC 5 Z9 5 U1 1 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 OCT PY 1992 VL 104 IS 4 BP 1611 EP 1617 DI 10.1086/116344 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JP900 UT WOS:A1992JP90000028 ER PT J AU BURATTI, BJ GIBSON, J MOSHER, JA AF BURATTI, BJ GIBSON, J MOSHER, JA TI CCD PHOTOMETRY OF THE URANIAN SATELLITES SO ASTRONOMICAL JOURNAL LA English DT Article ID VOYAGER; OBERON AB Broadband V and R CCD observations of the Uranian satellite system have been obtained over the full range of solar phase angles observable from Earth. These first visual observations of the phase curves of Miranda, A-riel, and Umbriel show that Ariel and Miranda exhibit the large opposition surges previously seen on the two outer Uranian satellites. Umbriel, however, lacks an appreciable opposition surge; its surface is either extremely compact or consists of small particles which lack a backscattered component. The tenuous structure of the other satellites is most likely due to the effects of eons of meteoritic gardening. C1 CALTECH,PALOMAR OBSERV,PASADENA,CA 91109. RP BURATTI, BJ (reprint author), JET PROP LAB,4800 OAK GROVE DR 183-501,PASADENA,CA 91109, USA. NR 29 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 OCT PY 1992 VL 104 IS 4 BP 1618 EP 1622 DI 10.1086/116345 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JP900 UT WOS:A1992JP90000029 ER PT J AU MASSA, D SHORE, SN WYNNE, D AF MASSA, D SHORE, SN WYNNE, D TI PHOTOSPHERIC VELOCITY-GRADIENTS IN B1 SUPERGIANTS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, EARLY-TYPE; SUPERGIANTS; ATMOSPHERES OF; MASS LOSS ID MODEL ATMOSPHERES; MASS-LOSS; STARS AB We present IUE spectra for a set of B1 supergiants. These data clearly demonstrate that the Si III lambda1300 multiplet (lower level 6.6 ev above ground) becomes progressively more asymmetric with increasing luminosity or, equivalently, mass loss. In the most luminous supergiants, the cores of the lambda1300 multiplets become displaced by up to -150 km s-1 relative to nearby, weaker lines. In addition, systematic velocity shifts and asymmetries are also present in the strong Si III singlets lambda1312 and lambda1417 in the more luminous stars. The obvious implication of these observations is that the outer photospheres of B supergiants are affected by radial expansion, and this may account for why even non-LTE line analyses of these stars require large micro-turbulent velocity fields, and why line blanketed LTE models underestimate their overall UV line blanketing. C1 NASA, GODDARD SPACE FLIGHT CTR, COMP SCI CORP, CODE 681, GREENBELT, MD 20771 USA. RP MASSA, D (reprint author), APPL RES CORP, 8201 CORP DR, LANDOVER, MD 20785 USA. NR 19 TC 11 Z9 11 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 OCT PY 1992 VL 264 IS 1 BP 169 EP 172 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR588 UT WOS:A1992JR58800025 ER PT J AU BOGGESS, NW MATHER, JC WEISS, R BENNETT, CL CHENG, ES DWEK, E GULKIS, S HAUSER, MG JANSSEN, MA KELSALL, T MEYER, SS MOSELEY, SH MURDOCK, TL SHAFER, RA SILVERBERG, RF SMOOT, GF WILKINSON, DT WRIGHT, EL AF BOGGESS, NW MATHER, JC WEISS, R BENNETT, CL CHENG, ES DWEK, E GULKIS, S HAUSER, MG JANSSEN, MA KELSALL, T MEYER, SS MOSELEY, SH MURDOCK, TL SHAFER, RA SILVERBERG, RF SMOOT, GF WILKINSON, DT WRIGHT, EL TI THE COBE MISSION - ITS DESIGN AND PERFORMANCE 2 YEARS AFTER LAUNCH SO ASTROPHYSICAL JOURNAL LA English DT Article DE ARTIFICIAL SATELLITES, SPACE PROBES; COSMIC MICROWAVE BACKGROUND ID COSMIC-BACKGROUND-EXPLORER; DIFFERENTIAL MICROWAVE RADIOMETERS; SATELLITE; SPECTRUM AB COBE, NASA's first space mission devoted primarily to cosmology, carries three scientific instruments to make precise measurements of the spectrum and anisotropy of the cosmic microwave background radiation on angular scales greater than 7-degrees and to conduct a search for a diffuse cosmic infrared background radiation with 0.7-degrees angular resolution. The mission goal is to make these measurements to the limit imposed by the local astrophysical foregrounds. The COBE instruments cover the wavelength range from 1.2 mum to 1 cm. The instruments are calibrated periodically in orbit using internal calibrators and celestial standards. The observing strategy is designed to minimize and allow determination of systematic errors that could result from spacecraft operations, the local environment of the spacecraft, and emission from foreground astrophysical sources such as the Galaxy and the solar system. The mission orbit and the scanning techniques provide full sky coverage, while simultaneously minimizing solar and terrestrial radiation on the instruments and reducing thermal and radiative perturbations of the measurements. The three instruments are complementary in that combined data from all are needed to discriminate cosmological emissions from other astrophysical sources. Operational experience after launch shows that flight performance generally meets or exceeds the design goals. COBE has now completed 2 years of flight operations, and a third year has been initiated. Initial COBE data products are planned for release in 1993 June. C1 MIT,DEPT PHYS,ROOM 20F-001,CAMBRIDGE,MA 01923. JET PROP LAB,PASADENA,CA 91109. GEN RES CORP,DANVERS,MA 01923. LAWRENCE BERKELEY LAB,SSL,BERKELEY,CA 94720. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP BOGGESS, NW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012 NR 42 TC 200 Z9 201 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1992 VL 397 IS 2 BP 420 EP 429 DI 10.1086/171797 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ075 UT WOS:A1992JQ07500006 ER PT J AU WILKING, BA GREENE, TP LADA, CJ MEYER, MR YOUNG, ET AF WILKING, BA GREENE, TP LADA, CJ MEYER, MR YOUNG, ET TI IRAS OBSERVATIONS OF YOUNG STELLAR OBJECTS IN THE CORONA AUSTRALIS DARK CLOUD SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, STARS; ISM, CLOUDS; ISM, INDIVIDUAL (CORONA AUSTRALIS CLOUD); STARS, PRE-MAIN-SEQUENCE ID FAR-INFRARED OBSERVATIONS; T-TAURI STARS; RHO-OPHIUCHI; MOLECULAR CLOUD; CLUSTER; ASSOCIATION; EVOLUTION; COMPLEXES; VICINITY; AUSTRINA AB We present an analysis of IRAS data for a 57 pc2 area of the nearby Corona Australis dark cloud complex. A total of 79 far-infrared sources are detected at 12 mum or in at least three IRAS bands. Combining these data with both newly obtained and previously published optical/infrared data, a total of 16 IRAS sources are identified with young stellar objects which are in close proximity to the R Coronae Australis cloud or Rossano Cloud B. Among these objects is a cold, heavily obscured young stellar object, IRAS 32, which radiates only in the 25-100 mum bands and is found to be associated with an extended near-infrared nebula. The majority of the remaining 63 IRAS sources in our sample appear to be related to field stars. A total of 24 young stellar objects are now known to be associated with the Cr A cloud and we investigate their collective properties through analysis of their spectral energy distributions. As observed for embedded populations in other dark clouds, the shapes of the spectral energy distributions constitute a nearly continuous sequence from cold, heavily obscured objects (extreme Class I) to T Tauri stars (Class II), with about equal numbers of Class I and Class II sources. There is a hint of a segregation of the shapes of the spectral energy distributions with source luminosity: eight of nine sources with L > 1.8 L. display Class I or flat energy distributions. We conclude that star formation in the Cr A cloud has proceeded in a manner similar to that in the rho Ophiuchi cloud in terms of duration and efficiency. We attribute the relatively low number of young stellar objects in Cr A to its lower mass of both low-density and high-density molecular gas. The luminosity function of the Cr A sources is unique only by the presence of six intermediate-luminosity (approximately 100 L.) objects. Either the cloud has formed intermediate-mass stars more efficiently than lower mass objects relative to other dark clouds or several of these objects are interlopers. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. RP WILKING, BA (reprint author), UNIV MISSOURI,DEPT PHYS & ASTRON,8001 NAT BRIDGE RD,ST LOUIS,MO 63121, USA. NR 44 TC 60 Z9 60 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 OCT 1 PY 1992 VL 397 IS 2 BP 520 EP 533 DI 10.1086/171808 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ075 UT WOS:A1992JQ07500017 ER PT J AU CHENG, FH HORNE, K PANAGIA, N SHRADER, CR GILMOZZI, R PARESCE, F LUND, N AF CHENG, FH HORNE, K PANAGIA, N SHRADER, CR GILMOZZI, R PARESCE, F LUND, N TI THE HUBBLE SPACE TELESCOPE OBSERVATIONS OF X-RAY NOVA MUSCAE 1991 AND ITS SPECTRAL EVOLUTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE NOVAE, CATACLYSMIC VARIABLES; STARS, INDIVIDUAL (NOVA MUSCAE 1991); ULTRAVIOLET STARS ID HOLE BINARY A0620-00; ACCRETION DISKS; BLACK-HOLE; EXTINCTION; MODEL AB We report HST/Faint Object Spectrograph (FOS) and Faint Object Camera (FOC) observations of X-ray Nova Muscae 1991 obtained on 1991 May 14-15. The FOS spectrum covering 1581-4807 angstrom shows a clear 2200 angstrom absorption feature. With a fit to the continuum considering the interstellar extinction and a power-law spectrum (f(nu) is-proportional-to nu(alpha)), we determine a color excess E(B - V) approximately 0.29 and a power-law slope of alpha approximately 0.30, which approximates a canonical accretion disk spectrum. By fitting a simple model of a steady state blackbody accretion disk around a black hole to the FOS spectrum and multiepoch data in the optical, UV, and X-ray bands, we estimate the lower limit mass of the central compact object M(min), the radius of the accretion disk R(out), the maximum orbital period P(max), and the upper limit mass transfer rate M(max) during the decline for several assumed values of the disk inclination angle i and distance D to the source. We find that M decays exponentially with a characteristic time of approximately 43 days. The cooling front predicted by the disk instability models to occur in the outer disk when T < 10(4) K should have been observable, but was not seen. C1 UNIV SCI & TECHNOL CHINA,CTR ASTROPHYS,HEFEI,ANHUI 230026,PEOPLES R CHINA. NASA,GODDARD SPACE FLIGHT CTR,COMPTON OBSERV,CTR SCI SUPPORT,CODE 6681,GREENBELT,MD 20771. DANISH SPACE RES INST,DK-2800 LYNGBY,DENMARK. RP CHENG, FH (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. NR 35 TC 39 Z9 40 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 OCT 1 PY 1992 VL 397 IS 2 BP 664 EP 673 DI 10.1086/171822 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ075 UT WOS:A1992JQ07500031 ER PT J AU WOODGATE, BE ROBINSON, RD CARPENTER, KG MARAN, SP SHORE, SN AF WOODGATE, BE ROBINSON, RD CARPENTER, KG MARAN, SP SHORE, SN TI DETECTION OF A PROTON-BEAM DURING THE IMPULSIVE PHASE OF A STELLAR FLARE SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ACTIVITY; STARS, FLARE; ULTRAVIOLET, STARS ID SOLAR-FLARES; X-RAY; ROTATIONAL MODULATION; ALPHA EMISSION; DRA SYSTEMS; RS CVN; DRACONIS; SPECTRUM; STARS; SUN AB A transient event consistent with the predicted temporal and spectral signatures of an energetic proton beam was detected in the impulsive phase of a small flare on the red dwarf star AU Microscopii. The 3 s long event was recorded with the Goddard High Resolution Spectrograph on the Hubble Space Telescope at 04:56:10 UT on 1991 September 3. It consisted of a prominent increase in the flux in the red wing of Lyman-alpha near 1223 angstrom, simultaneously with the peak of a flare observed in the 1206 angstrom transition region line of Si III. As anticipated, there was no corresponding increase in the blue wing of Lyman-alpha. Both Lyman-alpha wings were free of interfering emission from the geocorona. No other statistically significant intensity increase of either this magnitude or duration occurred during the four 30 minute time sequences taken on this date. The probability that the red wing event was a chance fluctuation is one chance in 2.5 x 10(4). This observation represents a confirmation of the prediction by Orrall & Zirker (1976) in which downstreaming protons accelerated during the impulsive phase of a flare charge exchange with ambient neutral hydrogen and emit Lyman-alpha radiation from 1 to 15 angstrom redward of line center. Further observations are needed to determine whether this phenomenon is a common characteristic of stellar flares. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAMS,CODE 681,GREENBELT,MD 20771. RP WOODGATE, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. RI Woodgate, Bruce/D-2970-2012; Carpenter, Kenneth/D-4740-2012 NR 22 TC 31 Z9 31 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 OCT 1 PY 1992 VL 397 IS 2 BP L95 EP L98 DI 10.1086/186553 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ077 UT WOS:A1992JQ07700007 ER PT J AU NUTH, JA ALLEN, JE AF NUTH, JA ALLEN, JE TI SUPERNOVAE AS SOURCES OF INTERSTELLAR DIAMONDS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID INFRARED-EMISSION; METEORITES; SURFACE; GRAINS; DUST; GRAPHITE; ORIGIN; 1987A AB Small hydrocarbon grains in the vicinity of a supernova could be annealed by the absorption of several far-ultraviolet photons to produce the tiny diamonds found in meteorites. These freshly-synthesized diamond grains would be bombarded by the heavy ions and neutrals in the supernovae outflow and would thereby acquire the distinctive noble-gas isotopic signature by which they were first isolated. Only diamonds formed relatively close to supernovae would acquire such a signature, since grains formed farther out would be subjected to a much diluted and less energetic plasma environment. RP NUTH, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTROCHEM BRANCH,GREENBELT,MD 20771, USA. RI Nuth, Joseph/E-7085-2012 NR 27 TC 39 Z9 39 U1 1 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD OCT PY 1992 VL 196 IS 1 BP 117 EP 123 DI 10.1007/BF00645245 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JX276 UT WOS:A1992JX27600009 ER PT J AU THOMPSON, AM HOGAN, KB HOFFMAN, JS AF THOMPSON, AM HOGAN, KB HOFFMAN, JS TI METHANE REDUCTIONS - IMPLICATIONS FOR GLOBAL WARMING AND ATMOSPHERIC CHEMICAL-CHANGE SO ATMOSPHERIC ENVIRONMENT PART A-GENERAL TOPICS LA English DT Note DE METHANE; GLOBAL WARMING; TROPOSPHERIC OZONE ID TROPOSPHERE; INCREASE; TRENDS; OZONE; CH4 AB Atmospheric methane (CH4) concentrations have more than doubled over the last two centuries. These increases may contribute to global warming, enhance formation of tropospheric ozone, suppress OH and affect stratospheric ozone. Calculations show that stabilization of CH4 could reduce projected temperature increases and possibly mitigate background tropospheric O3 increases due to increasing levels of CH4. C1 US EPA,OFF AIR & RADIAT,WASHINGTON,DC 20460. RP THOMPSON, AM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 26 TC 27 Z9 34 U1 2 U2 11 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0004-6981 J9 ATMOS ENVIRON A-GEN PD OCT PY 1992 VL 26 IS 14 BP 2665 EP 2668 DI 10.1016/0960-1686(92)90118-5 PG 4 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA JN299 UT WOS:A1992JN29900019 ER PT J AU KUMAR, KV WALIGORA, JM GILBERT, JH AF KUMAR, KV WALIGORA, JM GILBERT, JH TI THE INFLUENCE OF PRIOR EXERCISE AT ANAEROBIC THRESHOLD ON DECOMPRESSION-SICKNESS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB This study was conducted to examine the effects of exercise prior to decompression on the incidence of altitude decompression sickness (DCS). In a balanced, two-period, crossover trial, 39 healthy individuals (29 males, 10 females) of mean (S.D.) age 32.5 (7.7) years and body mass index 23.7 (3.4) were each exposed twice, without denitrogenation, to an altitude of 6,400 m (21,000 ft) in a hypobaric chamber. Under the experimental condition, subjects exercised at their predetermined anaerobic threshold levels for 30 min each day for 3 d prior to altitude exposure; the other condition was a non-exercise control. Under both conditions subjects performed exercise simulating space extravehicular activities at altitude for a period of 3 h, while breathing 100% oxygen. There were nine preferences (untied responses) for DCS, four under control and five under experimental conditions; all were Type 1, pain-only bends. No carryover effect between exposures was detected, and the test for treatment differences showed p = 0.56 (95% confidence interval = 0.34-0.58) for symptoms. No significant difference in DCS preferences was found after subjects exercised up to their anaerobic threshold levels during the days prior to decompression. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP KUMAR, KV (reprint author), KRUG LIFE SCI,ENVIRONM PHYSIOL LAB,1290 HERCULES DR,STE 120,HOUSTON,TX 77058, USA. NR 26 TC 2 Z9 3 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 OCT PY 1992 VL 63 IS 10 BP 899 EP 904 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JQ395 UT WOS:A1992JQ39500008 PM 1417653 ER PT J AU OTTERMAN, J BRAKKE, TW SUSSKIND, J AF OTTERMAN, J BRAKKE, TW SUSSKIND, J TI A MODEL FOR INFERRING CANOPY AND UNDERLYING SOIL TEMPERATURES FROM MULTIDIRECTIONAL MEASUREMENTS SO BOUNDARY-LAYER METEOROLOGY LA English DT Article AB Thermal emission is modeled from a canopy/soil surface, where the soil and the leaves are at different temperatures, T(g) and T(c) respectively. The temperature T(m) corresponding to a radiometer reading is given by B(lambda)(T(m)) = (chi)B(lambda)(T(g)) + (1 - chi) B(lambda)(T(c)) where B(lambda) denotes the Planck blackbody function at wavelength lambda, chi specifies the fraction of the field of view occupied by the soil at a given view direction, and an emissivity of 1.0 is assumed for the plants and the soil. The dependence of the soil-fraction chi on the view direction and the structure is expressed by the viewing-geometry parameter, which allows for concise and simple formulation. We observe from our model that at large view zenith angles, only the plants are effectively seen (that is, chi tends to zero), and therefore T(c) can be determined from observations at large zenith angles, to the extent that such observations are practical. Viewing from the zenith, chi = exp (- L(hc)), where L(hc) is the projection of the canopy leaf-area (per unit surface area) on a horizontal plane. For off-zenith observations, the soil-fraction chi depends on the distribution in the azimuth of the projected areas of various leaf categories, in addition to the dependence on the sum total of these projections, L(hc). L(hc), rather than the leaf-area index, emerges as the parameter characterizing the optical thickness of the canopy. Inferring both T(c) and T(g) from observations from the zenith and from large zenith angles is possible if L(hc) is known from other measurements. Drooping of leaves under water-stress conditions affects the observed temperature T(m) in a complicated way because a leaf-inclination change produces a change in L(hc) (for the same leaf area) and also a change in the dependence of chi on the view direction. Water stress can produce an increase of the soil-fraction chi and thus tends to produce an exaggerated increase in the observed temperature compared to the actual increase in canopy temperature. These effects are analyzed for a simulated soybean canopy. C1 TEL AVIV UNIV,IL-69978 TEL AVIV,ISRAEL. RP OTTERMAN, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 24 TC 18 Z9 23 U1 0 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0006-8314 J9 BOUND-LAY METEOROL JI Bound.-Layer Meteor. PD OCT PY 1992 VL 61 IS 1-2 BP 81 EP 97 DI 10.1007/BF02033996 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JQ051 UT WOS:A1992JQ05100005 ER PT J AU PORTER, T PRETLOW, R DSA, A NIXON, JV AF PORTER, T PRETLOW, R DSA, A NIXON, JV TI DERIVATION OF VOLUME-INDEPENDENT PARAMETERS OF THE TIME-RADIOFREQUENCY AMPLITUDE CURVE USING SONICATED ALBUMIN SO CIRCULATION LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. VIRGINIA COMMONWEALTH UNIV,MED COLL VIRGINIA,MCGUIRE VET ADM MED CTR,RICHMOND,VA 23298. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER HEART ASSOC PI DALLAS PA 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596 SN 0009-7322 J9 CIRCULATION JI Circulation PD OCT PY 1992 VL 86 IS 4 SU S BP 575 EP 575 PG 1 WC Cardiac & Cardiovascular Systems; Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA JT660 UT WOS:A1992JT66002307 ER PT J AU GOLDBERGER, AL BUNGO, MW BAEVSKY, RM BENNETT, BS RIGNEY, DR MIETUS, J NIKULINA, GA CHARLES, JB AF GOLDBERGER, AL BUNGO, MW BAEVSKY, RM BENNETT, BS RIGNEY, DR MIETUS, J NIKULINA, GA CHARLES, JB TI HEART-RATE DYNAMICS DURING LONG-TERM SPACE-FLIGHT - REPORT ON MIR COSMONAUTS SO CIRCULATION LA English DT Meeting Abstract C1 BETH ISRAEL HOSP,HARVARD THORNDIKE LAB,BOSTON,MA 02215. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX. MOSCOW BIOMED PROBLEMS INST,MOSCOW,USSR. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER HEART ASSOC PI DALLAS PA 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596 SN 0009-7322 J9 CIRCULATION JI Circulation PD OCT PY 1992 VL 86 IS 4 SU S BP 658 EP 658 PG 1 WC Cardiac & Cardiovascular Systems; Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA JT660 UT WOS:A1992JT66002636 ER PT J AU MINTZ, Y SERAFINI, YV AF MINTZ, Y SERAFINI, YV TI A GLOBAL MONTHLY CLIMATOLOGY OF SOIL-MOISTURE AND WATER-BALANCE SO CLIMATE DYNAMICS LA English DT Article ID PLANETARY BOUNDARY-LAYER; MODEL; PARAMETERIZATION; PRECIPITATION; EVAPORATION AB Global monthly climatology of available soil moisture content is derived on a 4-degrees by 5-degrees grid from observed precipitation and air surface temperature by use of a simple water budget model. The governing equations and methods of calculation for deriving these fields, which follow the formulation of Thornthwaite, are first described and the importance of the various assumptions and simplifications of this approach are discussed. The derived global fields are then presented. A comparison of some of the derived fields with other calculations is also made in order to permit an evaluation of the results: For example, our indirect estimate of the river run-off is generally in good agreement with more direct estimates, except for high latitude regions where the freezing of the soil may play an important role. C1 ECOLE NORM SUPER,METEOROL DYNAM LAB,CNRS,F-75231 PARIS 05,FRANCE. UNIV MARYLAND,DEPT METEOROL,COLL PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GODDARD LAB ATMOSPHERES,GREENBELT,MD 20771. NR 61 TC 94 Z9 100 U1 0 U2 5 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0930-7575 J9 CLIM DYNAM JI Clim. Dyn. PD OCT PY 1992 VL 8 IS 1 BP 13 EP 27 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JU111 UT WOS:A1992JU11100002 ER PT J AU WARREN, GP AF WARREN, GP TI APPLICATION OF MULTIGRID AND ADAPTIVE GRID EMBEDDING TO THE 2-DIMENSIONAL FLUX-SPLIT EULER EQUATIONS SO COMMUNICATIONS IN APPLIED NUMERICAL METHODS LA English DT Article; Proceedings Paper CT 5TH COPPER MOUNTAIN CONF ON MULTIGRID METHODS CY MAR 31-APR 05, 1991 CL COPPER MOUNTAIN, CO AB A numerical algorithm is presented for solving the two-dimensional flux-split Euler equations using a multigrid method with adaptive grid embedding. The method uses an unstructured data set along with a system of pointers for communication on the irregularly shaped grid topologies. An explicit two-stage time-advancement scheme is implemented. A multigrid algorithm is used to provide grid level communication and to accelerate the convergence of the solution to steady state. Results are presented for a NACA 0012 aerofoil in a free stream with a Mach number of 0.85 and an angle of attack of 1.0 degree. Excellent resolution of the shock structures is obtained with the adaptive grid embedding method with significantly fewer grid points than the comparable structured grid. RP WARREN, GP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0748-8025 J9 COMMUN APPL NUMER M PD OCT PY 1992 VL 8 IS 10 BP 771 EP 784 PG 14 WC Engineering, Multidisciplinary; Mathematics, Applied SC Engineering; Mathematics GA JU199 UT WOS:A1992JU19900007 ER PT J AU MATSON, P BERRYMAN, A AF MATSON, P BERRYMAN, A TI RATIO-DEPENDENT PREDATOR-PREY THEORY SO ECOLOGY LA English DT Editorial Material DE FUNCTIONAL RESPONSE; LOGISTIC EQUATION; METABOLIC POOL MODEL; PREDATOR PREY INTERACTIONS; PREY DEPENDENCE; RATIO DEPENDENCE; TROPHIC CASCADES; TROPHIC INTERACTIONS C1 WASHINGTON STATE UNIV,DEPT ENTOMOL,PULLMAN,WA 99164. WASHINGTON STATE UNIV,DEPT NAT RESOURCE SCI,PULLMAN,WA 99164. RP MATSON, P (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 2 Z9 2 U1 2 U2 7 PU ECOLOGICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE, NW, STE 400, WASHINGTON, DC 20036 SN 0012-9658 J9 ECOLOGY JI Ecology PD OCT PY 1992 VL 73 IS 5 BP 1528 EP 1528 PG 1 WC Ecology SC Environmental Sciences & Ecology GA JP740 UT WOS:A1992JP74000001 ER PT J AU HOCHSTEIN, LI AF HOCHSTEIN, LI TI ATP SYNTHESIS IN HALOBACTERIUM-SACCHAROVORUM - EVIDENCE THAT SYNTHESIS MAY BE CATALYZED BY AN F0F1-ATP SYNTHASE SO FEMS MICROBIOLOGY LETTERS LA English DT Article DE HALOBACTERIAL ATPASE; ARCHAEAL ATPASES; ATP SYNTHESIS; HALOBACTERIUM-SACCHAROVORUM ID CHEMIOSMOTIC ENERGY-CONVERSION; MEMBRANE-BOUND ATPASE; SULFOLOBUS-ACIDOCALDARIUS; ARCHAEBACTERIUM; PURIFICATION; HALOBIUM; SUBUNIT; COMPLEX; SYSTEM AB Halobacterium saccharovorum synthesized ATP in response to a pH shift from 8 to 6.2. Synthesis was inhibited by carbonyl cyanide m-chloro-phenylhydrazone, dicyclohexylcarbodiimide, and azide. Nitrate, an inhibitor of the membrane-bound ATPase previously isolated from this organism, did not inhibit ATP synthesis. N-Ethylmaleimide, which also inhibited this ATPase, stimulated the production of ATP. These observations suggested that H. saccharovorum synthesized and hydrolysed ATP using different enzymes and that the vacuolar-like ATPase activity previously described in H. saccharovorum was an ATPase whose function is yet to be identified. RP HOCHSTEIN, LI (reprint author), NASA,AMES RES CTR,PLANETARY BIOL BRANCH,M-S 239-4,MOFFETT FIELD,CA 94035, USA. NR 22 TC 10 Z9 11 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-1097 J9 FEMS MICROBIOL LETT JI FEMS Microbiol. Lett. PD OCT 1 PY 1992 VL 97 IS 1-2 BP 155 EP 159 PG 5 WC Microbiology SC Microbiology GA JP959 UT WOS:A1992JP95900026 ER PT J AU BOGGS, CH AF BOGGS, CH TI DEPTH, CAPTURE TIME, AND HOOKED LONGEVITY OF LONGLINE-CAUGHT PELAGIC FISH - TIMING BITES OF FISH WITH CHIPS SO FISHERY BULLETIN LA English DT Article ID YELLOWFIN AB To resolve the uncertainty in estimating capture depths of fish on pelagic longline gear, electronic microchip hook timers were attached to branch lines to record when bites occurred, and time-depth recorders (TDRs) were attached to longline gear, off Hawaii in January 1989 and January-February 1990. Hook timers indicated that 32% of the striped marlin Tetrapturus audax, 21% of the spearfish T. angustirostris, and 12% of the bigeye tuna Thunnus obesus were caught on sinking or rising hooks, demonstrating that capture time data are needed to correctly estimate capture depth. Recorded and predicted longline depths differed greatly, indicating that TDRs are essential for describing depth distributions of fish from longline catches. Most (> 60%) of the spearfish and striped marlin were caught on settled hooks (not sinking or rising) at depths of < 120 m, whereas most bigeye tuna were caught at depths of > 200 m. This suggests that eliminating shallow hooks could substantially reduce the bycatch of spearfish, striped marlin, and other recreationally important billfish without reducing fishing efficiency for bigeye tuna. Bigeye tuna and striped marlin survived up to 6-9 hours after capture, and over 50% of 12 frequently-caught taxa were alive when retrieved, suggesting that the release of live fish can be an effective management option. RP BOGGS, CH (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 28 TC 103 Z9 120 U1 1 U2 6 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 OCT PY 1992 VL 90 IS 4 BP 642 EP 658 PG 17 WC Fisheries SC Fisheries GA KQ944 UT WOS:A1992KQ94400002 ER PT J AU PARRISH, FA KAZAMA, TK AF PARRISH, FA KAZAMA, TK TI EVALUATION OF GHOST FISHING IN THE HAWAIIAN LOBSTER FISHERY SO FISHERY BULLETIN LA English DT Article AB Mortality due to retention of lobsters in derelict traps was evaluated over a 2-year period using two approaches. First, a string of eight empty, single-chamber, plastic traps was deployed at 40 m depth off Oahu, Hawaii, and monitored periodically by scuba during a 6-month period in 1990. The traps were stable and remained intact despite adverse oceanic conditions. Numerous entries and exits of lobsters were recorded. For the second test, the ability of lobsters to exit traps was tested in a series of field and laboratory trials of trap strings stocked with Hawaiian spiny lobster Panulirus marginatus and slipper lobster Scyllarides squammosus. The number of lobsters that died in stocked traps was less than 4% of the test population and differed significantly from zero only in the laboratory evaluation (chi2 5.42, P 0.02). The two species exited similarly; however, the pattern of exits in laboratory and field tests differed significantly (chi2 23.889, P 0.03). All lobsters exited within 56 days in a pattern generally approximating an exponential decline. Our evidence suggests that little direct mortality of lobsters is due to the inability to exit traps, and consequently ghost fishing by these traps is not considered a problem for spiny and slipper lobsters. RP PARRISH, FA (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 19 TC 11 Z9 11 U1 1 U2 5 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD OCT PY 1992 VL 90 IS 4 BP 720 EP 725 PG 6 WC Fisheries SC Fisheries GA KQ944 UT WOS:A1992KQ94400009 ER PT J AU SOMERTON, DA KIKKAWA, BS AF SOMERTON, DA KIKKAWA, BS TI POPULATION-DYNAMICS OF PELAGIC ARMORHEAD PSEUDOPENTACEROS-WHEELERI ON SOUTHEAST HANCOCK SEAMOUNT SO FISHERY BULLETIN LA English DT Article ID NORTH PACIFIC-OCEAN AB Pelagic armorhead Pseudopentaceros wheeleri are the target of a directed trawl fishery on many of the southern Emperor-northern Hawaiian Ridge seamounts. The population dynamics of armorhead for the period 1970-90 were reconstructed for Southeast Hancock seamount, the southernmost of the seamounts commercially fished, by using commercial catch-and-effort statistics, various biological measurements, and research stock-survey data. The population declined almost continuously from a 1972 high of 5500 metric tons (t) to a 1989 low of 25 t. In addition to the intense fishery, this decline was due partly to the sporadic pattern of armorhead recruitment. Natural mortality rate was estimated as 0.54/year; however, females had a higher mortality rate than males. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. NR 24 TC 13 Z9 13 U1 0 U2 2 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 OCT PY 1992 VL 90 IS 4 BP 756 EP 769 PG 14 WC Fisheries SC Fisheries GA KQ944 UT WOS:A1992KQ94400013 ER PT J AU SKILLMAN, RA BALAZS, GH AF SKILLMAN, RA BALAZS, GH TI LEATHERBACK TURTLE CAPTURED BY INGESTION OF SQUID BAIT ON SWORDFISH LONGLINE SO FISHERY BULLETIN LA English DT Note ID DERMOCHELYS-CORIACEA; SEA TURTLES RP SKILLMAN, RA (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 20 TC 1 Z9 1 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 OCT PY 1992 VL 90 IS 4 BP 807 EP 808 PG 2 WC Fisheries SC Fisheries GA KQ944 UT WOS:A1992KQ94400019 ER PT J AU DEHART, JM LOFGREN, GE JIE, L BENOIT, PH SEARS, DWG AF DEHART, JM LOFGREN, GE JIE, L BENOIT, PH SEARS, DWG TI CHEMICAL AND PHYSICAL STUDIES OF CHONDRITES .10. CATHODOLUMINESCENCE AND PHASE-COMPOSITION STUDIES OF METAMORPHISM AND NEBULAR PROCESSES IN CHONDRULES OF TYPE-3 ORDINARY CHONDRITES SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID UNEQUILIBRATED ORDINARY CHONDRITES; SYSTEM FRACTIONAL CRYSTALLIZATION; FEO-RICH CHONDRULES; INTERCHONDRULE MATRICES; CARBONACEOUS CHONDRITES; THERMO-LUMINESCENCE; AQUEOUS ALTERATION; SEMARKONA LL3.0; ORIGIN; OLIVINE AB The cathodoluminescence (CL) properties of eight type 3 ordinary chondrites and one L5 chondrite have been determined, and phenocryst and mesostasis compositions have been analyzed in the chondrules of four of them (Semarkona, type 3.0; Krymka, 3. 1; Allan Hills A77214, 3.5; and Dhajala, 3.8) in order to investigate their origins and metamorphic history. Two major classes of chondrule with eight subdivisions have been identified mainly on the basis of CL properties, and >95% of the chondrules can be assigned to these groups on the basis of phenocryst and mesostasis composition. Class A chondrules, consisting of those with plagioclase-normative mesostasis with bright CL, are subdivided into groups A1, A2, A3, A4, and A5. Class B chondrules, with little or no CL and having quartz-normative mesostases in the least metamorphosed chondrites which becomes feldspathic with metamorphism, are subdivided into groups B1, B2, and B3. Relationships between the eight chondrule groups can be deduced from their relative abundance in each of the nine chondrites. Groups A1, A2, B1, and A5 are present in Semarkona (15, 20, 60, 5% by number, respectively), group A5 chondrules in Semarkona being more heterogeneous than A5 chondrules in chondrites of higher petrologic type. Chondrule group Al evolves into A3 then A4 and then A5 during metamorphism while A2 evolves into A4 and then A5. Chondrule group B1 evolves into B2, B3, and then A5 but higher levels of metamorphism are required to complete the series than for the A1-5 series. Conversion of a group to an adjacent group can be observed in Allan Hills A77214 (3.5), where several chondrules are group B3 in their central regions and group A5 in their outer regions. The present chondrule groups are essentially independent of texture. Since group A and group B chondrules differ in bulk composition, redox state, and possibly oxygen isotope systematics, their relative abundance might be a factor in the creation of the nine chondrite classes. C1 UNIV ARKANSAS,DEPT CHEM & BIOCHEM,COSMOCHEM GRP,FAYETTEVILLE,AR 72701. RP DEHART, JM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 79 TC 33 Z9 33 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD OCT PY 1992 VL 56 IS 10 BP 3791 EP 3807 DI 10.1016/0016-7037(92)90171-E PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU619 UT WOS:A1992JU61900015 ER PT J AU KAISER, MK PROFFITT, DR AF KAISER, MK PROFFITT, DR TI USING THE STEREOKINETIC EFFECT TO CONVEY DEPTH - COMPUTATIONALLY EFFICIENT DEPTH-FROM-MOTION DISPLAYS SO HUMAN FACTORS LA English DT Article AB Recent developments in microelectronics have encouraged the use of 3D data bases to create compelling volumetric renderings of graphical objects. However, even with the computational capabilities of current-generation graphical systems, real-time displays of such objects are difficult, particularly when dynamic spatial transformations are involved. In this paper we discuss a type of visual stimulus (the stereokinetic effect display) that is computationally far less complex than a true three-dimensional transformation but yields an equally compelling depth impression, often perceptually indiscriminable from the true spatial transformation. Several possible applications for this technique are discussed (e.g., animating contour maps and air traffic control displays so as to evoke accurate depth percepts). C1 UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. RP KAISER, MK (reprint author), NASA,AMES RES CTR,MAIL STOP 262-3,MOFFETT FIELD,CA 94035, USA. NR 10 TC 4 Z9 4 U1 0 U2 0 PU HUMAN FACTORS SOC PI SANTA MONICA PA BOX 1369, SANTA MONICA, CA 90406 SN 0018-7208 J9 HUM FACTORS JI Hum. Factors PD OCT PY 1992 VL 34 IS 5 BP 571 EP 581 PG 11 WC Behavioral Sciences; Engineering, Industrial; Ergonomics; Psychology, Applied; Psychology SC Behavioral Sciences; Engineering; Psychology GA KA545 UT WOS:A1992KA54500005 PM 1459567 ER PT J AU SPENCER, JR MOORE, JM AF SPENCER, JR MOORE, JM TI THE INFLUENCE OF THERMAL INERTIA ON TEMPERATURES AND FROST STABILITY ON TRITON SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID ATMOSPHERE; PLUTO; NEPTUNE C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP SPENCER, JR (reprint author), LOWELL OBSERV,1400 W MARS HILL RD,FLAGSTAFF,AZ 86001, USA. NR 32 TC 49 Z9 49 U1 1 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 OCT PY 1992 VL 99 IS 2 BP 261 EP 272 DI 10.1016/0019-1035(92)90145-W PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100003 ER PT J AU HANSEN, CJ PAIGE, DA AF HANSEN, CJ PAIGE, DA TI A THERMAL-MODEL FOR THE SEASONAL NITROGEN-CYCLE ON TRITON SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID NEPTUNE; SURFACE; ATMOSPHERE C1 UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. RP HANSEN, CJ (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 38 TC 39 Z9 39 U1 1 U2 2 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 OCT PY 1992 VL 99 IS 2 BP 273 EP 288 DI 10.1016/0019-1035(92)90146-X PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100004 ER PT J AU RAGES, K POLLACK, JB AF RAGES, K POLLACK, JB TI VOYAGER IMAGING OF TRITONS CLOUDS AND HAZES SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID GEYSER-LIKE PLUMES; ATMOSPHERE; NEPTUNE; DYNAMICS; SURFACE; DUST C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP RAGES, K (reprint author), SPACE PHYS RES INST,SUNNYVALE,CA 94087, USA. NR 26 TC 12 Z9 12 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 OCT PY 1992 VL 99 IS 2 BP 289 EP 301 DI 10.1016/0019-1035(92)90147-Y PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100005 ER PT J AU PRYOR, WR WEST, RA SIMMONS, KE DELITSKY, M AF PRYOR, WR WEST, RA SIMMONS, KE DELITSKY, M TI HIGH-PHASE-ANGLE OBSERVATIONS OF NEPTUNE AT 2650-ANGSTROM AND 7500-ANGSTROM - HAZE STRUCTURE AND PARTICLE PROPERTIES SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID URANUS; PHOTOMETRY; VOYAGER-2; BALANCE; ALBEDOS; JUPITER C1 JET PROP LAB,PASADENA,CA 91109. RP PRYOR, WR (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,1234 INNOVAT DR,BOULDER,CO 80303, USA. NR 24 TC 22 Z9 22 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 OCT PY 1992 VL 99 IS 2 BP 302 EP 317 DI 10.1016/0019-1035(92)90148-Z PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100006 ER PT J AU MOSES, JI ALLEN, M YUNG, YL AF MOSES, JI ALLEN, M YUNG, YL TI HYDROCARBON NUCLEATION AND AEROSOL FORMATION IN NEPTUNE ATMOSPHERE SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID ION-INDUCED NUCLEATION; COSMIC-RAY GRADIENTS; SOLAR-CYCLE; PHOTOCHEMISTRY; URANUS; STRATOSPHERE; MESOSPHERE; VOYAGER-2; HAZE; CONDENSATION C1 CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. RI Moses, Julianne/I-2151-2013 OI Moses, Julianne/0000-0002-8837-0035 NR 94 TC 58 Z9 58 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1992 VL 99 IS 2 BP 318 EP 346 DI 10.1016/0019-1035(92)90149-2 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100007 PM 11538166 ER PT J AU HAMMEL, HB YOUNG, LA HACKWELL, J LYNCH, DK RUSSELL, R ORTON, GS AF HAMMEL, HB YOUNG, LA HACKWELL, J LYNCH, DK RUSSELL, R ORTON, GS TI VARIABILITY OF NEPTUNE 12.2-MU-M ETHANE EMISSION FEATURE SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID URANUS; STRATOSPHERE; METHANE; 10-MU-M; SPECTRA C1 MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. AEROSP CORP,SPACE SCI LAB,LOS ANGELES,CA 90009. JET PROP LAB,PASADENA,CA 91109. NR 15 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 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1992 VL 99 IS 2 BP 347 EP 352 DI 10.1016/0019-1035(92)90150-6 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100008 ER PT J AU KOSTIUK, T ROMANI, P ESPENAK, F BEZARD, B AF KOSTIUK, T ROMANI, P ESPENAK, F BEZARD, B TI STRATOSPHERIC ETHANE ON NEPTUNE - COMPARISON OF GROUNDBASED AND VOYAGER IRIS RETRIEVALS SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID INFRARED OBSERVATIONS; OCCULTATION; URANUS; TEMPERATURE; ATMOSPHERE; OBLATENESS; METHANE; SPECTRA; SYSTEM C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. OBSERV PARIS,F-92190 MEUDON,FRANCE. RI Romani, Paul/D-2729-2012; Kostiuk, Theodor/A-3077-2014 NR 22 TC 18 Z9 18 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 OCT PY 1992 VL 99 IS 2 BP 353 EP 362 DI 10.1016/0019-1035(92)90151-V PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100009 ER PT J AU MOSES, JI AF MOSES, JI TI METEOROID ABLATION IN NEPTUNE ATMOSPHERE SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID PLANETARY; VOYAGER-2; ORIGIN; DUST; STRATOSPHERE; PARTICLES; JUPITER; SULFUR; RINGS; LIGHT RP MOSES, JI (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,NATL RES COUNCIL,245-3,MOFFETT FIELD,CA 94035, USA. RI Moses, Julianne/I-2151-2013 OI Moses, Julianne/0000-0002-8837-0035 NR 46 TC 42 Z9 42 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 OCT PY 1992 VL 99 IS 2 BP 368 EP 383 DI 10.1016/0019-1035(92)90153-X PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100011 ER PT J AU BORUCKI, WJ PHAM, PC AF BORUCKI, WJ PHAM, PC TI OPTICAL-SEARCH FOR LIGHTNING ON NEPTUNE SO ICARUS LA English DT Article; Proceedings Paper CT NEPTUNE / TRITON CONF CY JAN 06-10, 1992 CL TUCSON, AZ ID ELECTROSTATIC DISCHARGES; JUPITER; VOYAGER-1; WHISTLERS; ATMOSPHERES; PLANETS; SYSTEM; CLOUD; VENUS C1 SETI INST,MT VIEW,CA 94043. RP BORUCKI, WJ (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 32 TC 4 Z9 4 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 OCT PY 1992 VL 99 IS 2 BP 384 EP 389 DI 10.1016/0019-1035(92)90154-Y PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JW591 UT WOS:A1992JW59100012 ER PT J AU BARNIV, Y AF BARNIV, Y TI APPLICATION OF VELOCITY FILTERING TO OPTICAL-FLOW PASSIVE RANGING SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article AB The sequence of images obtained from a passive forward-looking forward-traveling sensor provides the optical now on which passive ranging is based. Passive ranging is of interest in the context of nap-of-the-Earth helicopter obstacle avoidance. Ranging can be performed for some chosen features or, in principle, for all points in the field-of-view (field based) of the sensor. Velocity filtering is a track-before-detect algorithm that can be utilized to perform field-based passive ranging. We expand on the theoretical understanding and the performance analysis of the velocity filtering algorithm as applied to optical-flow-based ranging. RP BARNIV, Y (reprint author), NASA, AMES RES CTR, MS 210-9, MOFFETT FIELD, CA 94035 USA. NR 12 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD OCT PY 1992 VL 28 IS 4 BP 957 EP 969 DI 10.1109/7.165359 PG 13 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JV954 UT WOS:A1992JV95400004 ER PT J AU BARNIV, Y AF BARNIV, Y TI ERROR ANALYSIS OF COMBINED OPTICAL-FLOW AND STEREO PASSIVE RANGING SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID LOCATION AB The motion of an imaging sensor causes each imaged point of the scene to describe a time trajectory on the image plane. The trajectories of all imaged points are reminiscent of a flow (e.g., of liquid) which is the source of the term "optical flow". Optical-flow ranging is a method by which the stream of two-dimensional images obtained from a forward-looking forward-moving passive sensor is used to compute range to points in the field of view. Another well-known ranging method consists or triangulation based on stereo images obtained from at least two stationary sensors. In this paper we analyze the potential accuracies of a combined optical flow and stereo passive-ranging system in the context of helicopter nap-of-the-earth obstacle avoidance. The Cramer-Rao lower bound (CRLB) is developed for the combined system under the assumption of a random angular misalignment common to both cameras of a stereo pair. It is shown that the range accuracy degradations caused by misalignment is negligible for a combined optical-flow and stereo system as compared with a monocular optical-flow system. RP BARNIV, Y (reprint author), NASA,AMES RES CTR,MS 210-9,MOFFETT FIELD,CA 94035, USA. NR 13 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD OCT PY 1992 VL 28 IS 4 BP 978 EP 989 DI 10.1109/7.165361 PG 12 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JV954 UT WOS:A1992JV95400006 ER PT J AU OTOSHI, TY FRANCO, MM AF OTOSHI, TY FRANCO, MM TI DUAL PASSBAND DICHROIC PLATE FOR X-BAND SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note AB A need arose in the NASA Deep Space Network, a worldwide tracking system, for a dichroic plate that would be transparent at two desired frequency bands in the X-band region and be totally reflective at S-band. The dual-passband dichroic plate that was developed to meet the technical requirements is a thick metallic plate having an array of periodic round holes filled with Teflon plugs. Test results on an experimental prototype plate indicate that it is technically possible to design a dielectrically filled dichroic plate that meets all of these technical requirements. RP OTOSHI, TY (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 15 TC 4 Z9 4 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 OCT PY 1992 VL 40 IS 10 BP 1238 EP 1245 DI 10.1109/8.182457 PG 8 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA KJ455 UT WOS:A1992KJ45500015 ER PT J AU ZIMMERMAN, ML LEE, SW FUJIKAWA, G AF ZIMMERMAN, ML LEE, SW FUJIKAWA, G TI ANALYSIS OF REFLECTOR ANTENNA SYSTEM INCLUDING FREQUENCY SELECTIVE SURFACES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note AB Frequency selective surfaces (FSS's) are often used in spaceborne applications of reflector antennas due to their ability to allow multiple feeds to utilize the same reflector dish. The problems inherent in evaluating the FSS separately from the reflector system are discussed. A method of integrating the FSS effects into the reflector system analysis is presented. An example is given for the proposed Advanced Tracking and Delay Relay Satellite System (ATDRSS) single-access triband reflector antenna. C1 UNIV ILLINOIS,DEPT ELECT ENGN,URBANA,IL 61801. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP ZIMMERMAN, ML (reprint author), ANALEX CORP,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 3 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD OCT PY 1992 VL 40 IS 10 BP 1264 EP 1266 DI 10.1109/8.182463 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA KJ455 UT WOS:A1992KJ45500021 ER PT J AU SONG, YD MIDDLETON, RH AF SONG, YD MIDDLETON, RH TI DEALING WITH THE TIME-VARYING PARAMETER PROBLEM OF ROBOT MANIPULATORS PERFORMING PATH TRACKING TASKS SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note AB Many robotic applications involve time-varying payloads during the operation of the robot. It is therefore of interest to consider control schemes that deal with time-varying parameters. Using the properties of the element by element (or Hadarmad) product of matrices, we obtain the robot dynamics in parameter-isolated form, from which a new control scheme is developed. The controller proposed yields zero asymptotic tracking errors when applied to robotic systems with time-varying parameters by using a switching type control law. The results obtained are global in the initial state of the robot, and can be applied to rapidly varying systems. C1 UNIV NEWCASTLE,DEPT ELECT ENGN & COMP SCI,NEWCASTLE,NSW 2308,AUSTRALIA. RP SONG, YD (reprint author), N CAROLINA AGR & TECHNOL STATE UNIV,NASA,CTR RES EXCELLENCE,CONTROLS & GUIDANCE GRP,GREENSBORO,NC 27411, USA. RI Middleton, Richard/A-2950-2013; Song, Yong-Duan/A-2730-2015 OI Middleton, Richard/0000-0001-9885-8803; NR 18 TC 11 Z9 11 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD OCT PY 1992 VL 37 IS 10 BP 1597 EP 1601 DI 10.1109/9.256391 PG 5 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA JW239 UT WOS:A1992JW23900028 ER PT J AU WHITAKER, SR MAKI, GK AF WHITAKER, SR MAKI, GK TI SELF SYNCHRONIZED ASYNCHRONOUS SEQUENTIAL PASS TRANSISTOR-CIRCUITS SO IEEE TRANSACTIONS ON COMPUTERS LA English DT Note DE ASYNCHRONOUS SEQUENTIAL CIRCUITS; ASYNCHRONOUS STATE MACHINES; PASS TRANSISTORS; SINGLE TRANSITION TIME (STT) STATE ASSIGNMENTS; STATE ASSIGNMENTS; VERY LARGE SCALE INTEGRATED (VLSI) CIRCUITS AB A new class of CMOS VLSI asynchronous sequential circuits utilizing pass transistors is introduced. This class of self synchronizing circuits eliminates the need for critical race free state assignments. These circuits synchronize the transition path action by forcing the circuit to sequence through proper unstable states. RP WHITAKER, SR (reprint author), UNIV IDAHO,DEPT ELECT ENGN,NASA,SPACE ENGN RES CTR VLSI SYST DESIGN,MOSCOW,ID 83843, USA. NR 9 TC 2 Z9 2 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 0018-9340 J9 IEEE T COMPUT JI IEEE Trans. Comput. PD OCT PY 1992 VL 41 IS 10 BP 1344 EP 1348 DI 10.1109/12.166614 PG 5 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA JX253 UT WOS:A1992JX25300016 ER PT J AU ROBINSON, PA COAKLEY, P AF ROBINSON, PA COAKLEY, P TI SPACECRAFT CHARGING - PROGRESS IN THE STUDY OF DIELECTRICS AND PLASMAS SO IEEE TRANSACTIONS ON ELECTRICAL INSULATION LA English DT Review ID ELECTRON-BEAM EXPERIMENTS; HIGH-ALTITUDES; DUSTY PLASMAS; EMISSION; ENVIRONMENT; POTENTIALS; PARTICLES; VEHICLE; SATURN; RINGS AB An object, whether conducting or not, takes on a charge in a plasma. If the object is a spacecraft, and the plasma is provided by a planetary magnetosphere, the act of charging can produce a variety of unwanted effects. During the last twenty years, spacecraft have been flown specifically to measure charging and discharging effects; ground experiments, performed to measure the fundamental properties of materials used in spacecraft, have provided charging parameters and testing procedures and guidelines for entire spacecraft design. This review summarizes the progress. C1 JAYCOR,SAN DIEGO,CA. RP ROBINSON, PA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 111 TC 32 Z9 35 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 0018-9367 J9 IEEE T ELECTR INSUL PD OCT PY 1992 VL 27 IS 5 BP 944 EP 960 DI 10.1109/14.256471 PG 17 WC Engineering, Electrical & Electronic SC Engineering GA JR809 UT WOS:A1992JR80900003 ER PT J AU LAI, R BHATTACHARYA, PK YANG, D BROCK, TL ALTEROVITZ, SA DOWNEY, AN AF LAI, R BHATTACHARYA, PK YANG, D BROCK, TL ALTEROVITZ, SA DOWNEY, AN TI CHARACTERISTICS OF 0.8-MU-M AND 0.2-MU-M GATE LENGTH INXGA1-XAS IN0.52AL0.48AS INP (0.53-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.70) MODULATION-DOPED FIELD-EFFECT TRANSISTORS AT CRYOGENIC TEMPERATURES SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article ID TRANSPORT AB We have investigated analytically and experiment tally the performance characteristics of InP-based InxGa1-xAs/In0.52Al0.48As (0.53 less-than-or-equal-to x less-than-or-equal-to 0.70) pseudomorphic modulation-doped field-effect transistors (MODFET's) as a function of strain in the channel, gate, length, and temperature. The strain in the channel was varied by varying the In composition x. The temperature was varied in the range of 40-300 K and the devices have gate lengths L(g) of 0.8 and 0.2-mu-m. Analysis of the device was done using a one-dimensional self-consistent solution of the Poisson and Schrodinger equations in the channel, a two-dimensional Poisson solver to obtain the channel electric field, and a Monte Carlo simulation to estimate the carrier transit times in the channel. An increase in the value of the cutoff frequency is predicted for an increase in In composition, a decrease in temperature, and a decrease in gate length. The improvements seen with decreasing temperature, decreasing gate length, and increased In composition were smaller than those predicted by analysis. The experimental results on pseudomorphic InGaAs/InAlAs MODFET's have shown that there is a 15-30% improvement in cutoff frequency in both the 0.8- and 0.2-mu-m gate length devices when the temperature is lowered from 300 to 40 K. C1 UNIV MICHIGAN,SOLID STATE ELECTR LAB,ANN ARBOR,MI 48109. NASA,LEWIS RES CTR,DIV SPACE ELECTR,CLEVELAND,OH 44135. RP LAI, R (reprint author), UNIV MICHIGAN,CTR HIGH FREQUENCY MICROELECTR,ANN ARBOR,MI 48109, USA. NR 13 TC 17 Z9 17 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 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD OCT PY 1992 VL 39 IS 10 BP 2206 EP 2213 DI 10.1109/16.158789 PG 8 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA JP308 UT WOS:A1992JP30800003 ER PT J AU OTOSHI, TY FRANCO, MM AF OTOSHI, TY FRANCO, MM TI MEASUREMENTS OF A DEEP SPACE STATION FRACTIONAL FREQUENCY STABILITY TO THE 10(-15) LEVEL SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article AB This article presents techniques for measuring the frequency stability of a deep space station that was configured with a new X-band transmitter subsystem to enable high-quality radio science data to be obtained for a Gravity Wave Experiment. The instrument and test procedures for performing frequency stability measurements in the field are described. Test results from measurements made on various transmit and receive subsystems, as well as the overall transmit-receive end-to-end systems below the antenna feed horn are presented. The subsystem test data proved to be useful for assessing the frequency stabilities of various subsystems. This assessment led to design improvements needed to meet stringent frequency stability requirements for forthcoming gravity wave experiments. RP OTOSHI, TY (reprint author), JET PROP LAB,COMMUN ELEMENTS RES SECT,PASADENA,CA 91109, 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 0018-9456 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD OCT PY 1992 VL 41 IS 5 BP 577 EP 587 DI 10.1109/19.177326 PG 11 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JZ107 UT WOS:A1992JZ10700001 ER PT J AU SARMA, GR BARRANGER, JP AF SARMA, GR BARRANGER, JP TI CAPACITANCE-TYPE BLADE-TIP CLEARANCE MEASUREMENT SYSTEM USING A DUAL AMPLIFIER WITH RAMP DC INPUTS AND INTEGRATION SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article ID OPERATIONAL-AMPLIFIER AB The analysis and prototype results of a dual-amplifier circuit for measuring blade-tip clearance in turbine engines are presented. The capacitance between the blade tip and mounted capacitance electrode within a guard ring of a probe forms one of the feedback elements of an operational amplifier (op amp). The differential equation governing the circuit taking into consideration the nonideal features of the op amp was formulated and solved for two types of inputs (ramp and DC) that are of interest for the application. Under certain time-dependent constraints, it is shown that (1) with a ramp input the circuit has an output voltage proportional to the static tip clearance capacitance, and (2) with a DC input, the output is proportional to the derivative of the clearance capacitance, and subsequent integration recovers the dynamic capacitance. The technique accommodates long cable lengths and environmentally induced changes in cable and probe parameters. System implementation for both static and dynamic measurements having the same high sensitivity is also presented. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 10 TC 6 Z9 8 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 OCT PY 1992 VL 41 IS 5 BP 674 EP 678 DI 10.1109/19.177341 PG 5 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JZ107 UT WOS:A1992JZ10700016 ER PT J AU BETHEA, MD ROSENTHAL, BN AF BETHEA, MD ROSENTHAL, BN TI AN AUTOMATED THERMOCOUPLE CALIBRATION SYSTEM SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Note AB An Automated Thermocouple Calibration System (ATCS) was developed for the unattended calibration of type K thermocouples. This system operates from room temperature to 650-degrees-C and has been used for calibration of thermocouples in an eight-zone furnace system which may employ as many as 60 thermocouples simultaneously. It is highly efficient, allowing for the calibration of large numbers of thermocouples in significantly less time than required for manual calibrations. The system consists of a personal computer, a data acquisition/control unit, and a laboratory calibration furnace. The calibration furnace is a microprocessor-controlled multipurpose temperature calibrator with an accuracy of +/-.7-degrees-C. The accuracy of the calibration furnace is traceable to the National Institute of Standards and Technology (NIST). The computer software is menu-based to give the user flexibility and ease of use. The user needs no programming experience to operate the systems. This system was specifically developed for use in the Microgravity Materials-Science Laboratory (MMSL) at the NASA LeRC. RP BETHEA, MD (reprint author), NASA,LEWIS RES CTR,MICROGRAV MAT SCI LAB,PROC SCI & TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 8 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 OCT PY 1992 VL 41 IS 5 BP 702 EP 706 DI 10.1109/19.177346 PG 5 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JZ107 UT WOS:A1992JZ10700021 ER PT J AU SOLI, GA BLAES, BR BUEHLER, MG AF SOLI, GA BLAES, BR BUEHLER, MG TI PROTON-SENSITIVE CUSTOM SRAM DETECTOR SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1991 NUCLEAR SCIENCE SYMP AND MEDICAL IMAGING CONF ( NSS / MIUC ) CY NOV 02-09, 1991 CL SANTA FE, NM SP IEEE, NUCL & PLASMA SCI SOC AB Because of the recently discovered importance of protons to the upset of spaceborne electronics, a custom 4k-bit SRAM chip was tested with protons. The SRAM was developed to determine the Single Event Upset hardness of CMOS latches using alpha particle measurements, by adjusting an offset voltage that reduces the charge required to upset a cell. The proton experiments were designed to observe both proton and silicon recoil produced ionization. The silicon recoils were generated by protons undergoing nuclear coulomb scattering. It was discovered that silicon recoil produced charge can be collected from very deep in the silicon substrate. This paper describes a calibration procedure for the SRAM detector. Source spectra were acquired with this chip by measuring the number of upset cells versus offset voltage. RP SOLI, GA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 5 TC 3 Z9 3 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD OCT PY 1992 VL 39 IS 5 BP 1374 EP 1378 DI 10.1109/23.173209 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA JZ684 UT WOS:A1992JZ68400034 ER PT J AU HADDAD, ZS PARKINS, BE AF HADDAD, ZS PARKINS, BE TI DESIGNING DOPPLER SIGNALS TO OVERCOME TRANSMISSION NONLINEARITIES SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article AB Doppler processing requires a radiating signal with low spectral sidelobes over the range of frequencies at which Doppler shifts are expected. This is conventionally achieved by "windowing" the driving sine wave. The effectiveness of windowing depends upon the transmitter amplitude response and therefore is affected by nonlinearity. When significant, this problem can be overcome by the proposed design. It entails gating the sine wave with a series of nonuniformly spaced pulses of constant duration and amplitude. The pulse start times then control the shape and level of the radiated spectrum; the most closely controlled sidelobes are those near the transmitted frequency. The resulting spectrum is not affected by nonzero threshold or limited linear range (typical sources of nonlinearity). Furthermore, amplitude shading (within the linear range) and pulse-duration variation can be introduced to control sidelobe levels at higher Doppler frequencies. Perhaps more interesting, pulse-to-pulse phase shifts allow one to design a signal whose central spectral peak is shifted from the perceived transmitted frequency. C1 AT&T BELL LABS,WHIPPANY,NJ 07981. RP HADDAD, ZS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 8 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 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD OCT PY 1992 VL 40 IS 10 BP 2459 EP 2463 DI 10.1109/78.157289 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA JQ504 UT WOS:A1992JQ50400007 ER PT J AU PAL, SK AF PAL, SK TI FUZZY SET THEORETIC MEASURES FOR AUTOMATIC FEATURE EVALUATION .2. SO INFORMATION SCIENCES LA English DT Article AB The present paper is a continuation of our previous work [1] in which we developed an algorithm for automatic ranking of the individual feature importance for pattern recognition problems. Here we have extended the work by (i) evaluating the importance of any subset of features collectively (ii) providing an average feature evaluation index considering all the classes and (iii) comparing the results with those of statistical measures considering their variation with interest distance. Effectiveness of the algorithm is demonstrated on six-class, three-feature vowel data; four-class, five-feature consonant data; and three-class fifteen-feature mango leaf data. C1 NASA,LYNDON B JOHNSON SPACE CTR,DIV INFORMAT TECHNOL,SOFTWARE TECHNOL BRANCH PT4,HOUSTON,TX 77058. RP PAL, SK (reprint author), INDIAN STAT INST,ELECTR & COMMUNICAT SCI UNIT,CALCUTTA 700035,W BENGAL,INDIA. NR 11 TC 27 Z9 28 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0020-0255 J9 INFORM SCIENCES JI Inf. Sci. PD OCT 1 PY 1992 VL 64 IS 1-2 BP 165 EP 179 DI 10.1016/0020-0255(92)90118-R PG 15 WC Computer Science, Information Systems SC Computer Science GA HY345 UT WOS:A1992HY34500013 ER PT J AU PINELLI, TE BISHOP, AP BARCLAY, RO KENNEDY, JM AF PINELLI, TE BISHOP, AP BARCLAY, RO KENNEDY, JM TI THE ELECTRONIC TRANSFER OF INFORMATION AND AEROSPACE KNOWLEDGE DIFFUSION SO INTERNATIONAL FORUM ON INFORMATION AND DOCUMENTATION LA English DT Article AB Increasing reliance on and investment in information technology and electronic networking systems presupposes that computing and information technology will play a major role in the diffusion of aerospace knowledge. Little is known, however, about actual information technology needs, uses, and problems within the aerospace knowledge diffusion process. The authors state that the potential contributions of information technology to increased productivity and competitiveness will be diminished unless empirically derived knowledge regarding the information-seeking behavior of the members of the social system-those who are producing, transferring, and using scientific and technical information-is incorporated into a new technology policy framework. Research into the use of information technology and electronic networks by U. S. aerospace engineers and scientists, collected as part of a research project designed to study aerospace knowledge diffusion, is presented in support of this assertion. C1 UNIV ILLINOIS,GRAD SCH LIB & INFORMAT SCI,URBANA,IL 61801. RENSSELAER POLYTECH INST,DEPT LANGUAGE LITERATURE & COMMUNICAT,TROY,NY 12180. INDIANA UNIV,CTR SURVEY RES,BLOOMINGTON,IN 47405. RP PINELLI, TE (reprint author), NASA,LANGLEY RES CTR,DIV RES INFORMAT & APPLICAT,HAMPTON,VA 23681, USA. NR 38 TC 0 Z9 0 U1 1 U2 1 PU INT FEDERAT INFORMATION & DOCUMENTATION PI THE HAGUE PA PO BOX 90402, 2509 LK THE HAGUE, NETHERLANDS SN 0304-9701 J9 INT FORUM INFORM DOC JI Int. Forum Inf. Doc. PD OCT PY 1992 VL 17 IS 4 BP 8 EP 16 PG 9 WC Information Science & Library Science SC Information Science & Library Science GA LY015 UT WOS:A1992LY01500003 ER PT J AU SPEZIALE, CG THANGAM, S AF SPEZIALE, CG THANGAM, S TI ANALYSIS OF AN RNG BASED TURBULENCE MODEL FOR SEPARATED FLOWS SO INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE LA English DT Article ID NEAR-WALL; REYNOLDS AB A two-equation turbulence model of die K - epsilon-type was recently derived by Yakhot and Orszag based on Renormalization Group (RNG) methods. It was later reported that this RNG based model yields substantially better predictions than the standard K - epsilon-model for turbulent flow over a backward facing step-a standard test case used to benchmark the performance of turbulence models in separated flows. The apparent improvements obtained from the RNG K - epsilon-model were attributed to the better treatment of near wall turbulence effects. In contrast to these earlier claims, it is shown in this paper that the original version of the RNG K - epsilon-model substantially underpredicts the reattachment point in the backstep problem-a deficiency that is traced to the modeling of the production of dissipation term. However, with the most recent improvements in the RNG K - epsilon-model proposed by Yakhot and co-workers, excellent results for the backstep problem are now obtained. Interestingly enough, these results are not that sensitive to the details of the near wall treatment. C1 STEVENS INST TECHNOL, DEPT MECH ENGN, HOBOKEN, NJ 07030 USA. RP NASA, LANGLEY RES CTR, INST COMP APPLICAT SCI & ENGN, HAMPTON, VA 23665 USA. NR 23 TC 75 Z9 114 U1 1 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7225 EI 1879-2197 J9 INT J ENG SCI JI Int. J. Eng. Sci. PD OCT PY 1992 VL 30 IS 10 BP 1379 EP 1388 DI 10.1016/0020-7225(92)90148-A PG 10 WC Engineering, Multidisciplinary SC Engineering GA JK832 UT WOS:A1992JK83200013 ER PT J AU SPEZIALE, CG AF SPEZIALE, CG TI THE ERINGEN ANNIVERSARY ISSUE - A COLLECTION OF ARTICLES ON ENGINEERING SCIENCE DEDICATED TO ERINGEN,A.C. BY HIS FORMER STUDENTS, COLLEAGUES AND FRIENDS ON THE OCCASION OF HIS 70TH BIRTHDAY - DEDICATION SO INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE LA English DT Item About an Individual RP SPEZIALE, CG (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665, USA. NR 1 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 0020-7225 J9 INT J ENG SCI JI Int. J. Eng. Sci. PD OCT PY 1992 VL 30 IS 10 BP R11 EP R23 DI 10.1016/0020-7225(92)90136-5 PG 13 WC Engineering, Multidisciplinary SC Engineering GA JK832 UT WOS:A1992JK83200002 ER PT J AU SPEZIALE, CG AF SPEZIALE, CG TI THE ERINGEN ANNIVERSARY ISSUE - A COLLECTION OF ARTICLES ON ENGINEERING SCIENCE DEDICATED TO ERINGEN,A.C. BY HIS FORMER STUDENTS, COLLEAGUES AND FRIENDS ON THE OCCASION OF HIS 70TH BIRTHDAY - PREFACE SO INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE LA English DT Editorial Material RP SPEZIALE, CG (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665, 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 0020-7225 J9 INT J ENG SCI JI Int. J. Eng. Sci. PD OCT PY 1992 VL 30 IS 10 BP R9 EP & DI 10.1016/0020-7225(92)90135-4 PG 0 WC Engineering, Multidisciplinary SC Engineering GA JK832 UT WOS:A1992JK83200001 ER PT J AU KIM, SW BENSON, TJ AF KIM, SW BENSON, TJ TI CALCULATION OF A CIRCULAR JET IN CROSS-FLOW WITH A MULTIPLE-TIME-SCALE TURBULENCE MODEL SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article ID FLOWS; CHANNEL AB Calculation of a three-dimensional turbulent flow of a jet in a crossflow using a multiple-time-scale turbulence model is presented. The turbulence in the forward region of the jet is in a stronger non-equilibrium state than that in the wake region of the jet, while the turbulence level in the wake region is higher than that in the front region. The calculated flow and the concentration fields are in very good agreement with the measured data, and it indicates that the turbulent transport of mass, concentration and momentum is strongly governed by the non-equilibrium turbulence. The capability of the multiple-time-scale turbulence model to resolve the non-equilibrium turbulence field is also discussed. RP KIM, SW (reprint author), NASA,LEWIS RES CTR,MS 5-11,CLEVELAND,OH 44135, USA. NR 17 TC 31 Z9 32 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0017-9310 J9 INT J HEAT MASS TRAN JI Int. J. Heat Mass Transf. PD OCT PY 1992 VL 35 IS 10 BP 2357 EP 2365 DI 10.1016/0017-9310(92)90078-7 PG 9 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA JV957 UT WOS:A1992JV95700004 ER PT J AU SIEGEL, R MOLLS, FB AF SIEGEL, R MOLLS, FB TI FINITE-DIFFERENCE SOLUTION FOR TRANSIENT RADIATIVE COOLING OF A CONDUCTING SEMITRANSPARENT SQUARE REGION SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article ID DIMENSIONAL RECTANGULAR ENCLOSURE; GRAY PARTICIPATING MEDIA; HEAT-TRANSFER; BOUNDARY-CONDITIONS; TRANSPORT-EQUATION; TEMPERATURE; EQUILIBRIUM AB Transient solutions were obtained for a square region of heat conducting semitransparent material cooling by thermal radiation. The region is in a vacuum environment, so energy is dissipated only by radiation from within the medium leaving through its boundaries. The effect of heat conduction during the transient is to partially equalize the internal temperature distribution. As the optical thickness of the region is increased, the temperature gradients increase near the boundaries and corners, unless heat conduction is large. The solution procedure must provide accurate temperature distributions in these regions to prevent error in the calculated radiation losses. Two-dimensional numerical Gaussian integration is used to obtain the local radiative source term. A finite difference procedure with variable space and time increments is used to solve the transient energy equation. Variable spacing was used to concentrate grid points in regions with large temperature gradients. RP SIEGEL, R (reprint author), NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 27 TC 8 Z9 8 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0017-9310 EI 1879-2189 J9 INT J HEAT MASS TRAN JI Int. J. Heat Mass Transf. PD OCT PY 1992 VL 35 IS 10 BP 2579 EP 2592 DI 10.1016/0017-9310(92)90100-7 PG 14 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA JV957 UT WOS:A1992JV95700026 ER PT J AU DIB, NI HAROKOPUS, WP PONCHAK, GE KATEHI, LPB AF DIB, NI HAROKOPUS, WP PONCHAK, GE KATEHI, LPB TI A COMPARATIVE-STUDY BETWEEN SHIELDED AND OPEN COPLANAR WAVE-GUIDE DISCONTINUITIES SO INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE COMPUTER-AIDED ENGINEERING LA English DT Article ID WAVE-GUIDE AB A comparative study between open and shielded coplanar waveguide (CPW) discontinuities is presented. In this study, the space domain integral equation method is used to characterize several discontinuities such as the open-end CPW and CPW series stubs. Two different geometries of CPW series stubs (straight and bent stubs) are compared with respect to resonant frequency and radiation loss. In addition, the encountered radiation loss due to different CPW shunt stubs is evaluated experimentally. The notion of forced radiation simulation is presented, and the results of such a simulation are compared to the actual radiation loss obtained rigorously. It is shown that such a simulation cannot give reliable results concerning radiation loss from printed circuits. C1 TEXAS INSTRUMENTS INC,DALLAS,TX 75070. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP DIB, NI (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, USA. RI Dib, Nihad/M-4918-2015; OI Dib, Nihad/0000-0002-2263-5512 NR 38 TC 13 Z9 13 U1 0 U2 1 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 1050-1827 J9 INT J MICROWAVE MILL JI Int. J. Microw. Millimeter-Wave Comput.-Aided Eng. PD OCT PY 1992 VL 2 IS 4 BP 331 EP 341 DI 10.1002/mmce.4570020413 PG 11 WC Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA JL929 UT WOS:A1992JL92900012 ER PT J AU WOOD, BL BECK, LR WASHINO, RK HIBBARD, KA SALUTE, JS AF WOOD, BL BECK, LR WASHINO, RK HIBBARD, KA SALUTE, JS TI ESTIMATING HIGH MOSQUITO-PRODUCING RICE FIELDS USING SPECTRAL AND SPATIAL DATA SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID CLASSIFICATION AB The cultivation of irrigated rice provides ideal larval habitat for a number of anopheline vectors of malaria throughout the world. Anopheles freeborni, a potential vector of human malaria, is associated with the nearly 240000 hectares of irrigated rice grown annually in Northern and Central California; therefore, this species can serve as a model for the study of rice field anopheline population dynamics. Analysis of field data revealed that rice fields with early season canopy development, that are located near bloodmeal sources (i.e., pastures with livestock) were more likely to produce anopheline larvae than fields with less developed canopies located further from pastures. Remote sensing reflectance measurements of early-season canopy development and geographic information system (GIS) measurements of distances between rice fields and pastures with livestock were combined to distinguish between high and low mosquito-producing rice fields. Using spectral and distance measures in either a discriminant or Bayesian analysis, the identification of high mosquito-producing fields was made with 85 per cent accuracy nearly two months before anopheline larval populations peaked. Since omission errors were also minimized by these approaches, they could provide a new basis for directing abatement techniques for the control of malaria vectors. C1 UNIV CALIF DAVIS,DEPT ENTOMOL,DAVIS,CA 95616. RP WOOD, BL (reprint author), NASA,AMES RES CTR,TGS TECHNOL INC,MS 242-4,MOFFETT FIELD,CA 94035, USA. NR 23 TC 44 Z9 48 U1 3 U2 11 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 OCT PY 1992 VL 13 IS 15 BP 2813 EP 2826 PG 14 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA JT898 UT WOS:A1992JT89800006 ER PT J AU KREUTZDELGADO, K LONG, M SERAJI, H AF KREUTZDELGADO, K LONG, M SERAJI, H TI KINEMATIC ANALYSIS OF 7-DOF MANIPULATORS SO INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH LA English DT Article ID REDUNDANT MANIPULATORS; CONFIGURATION CONTROL AB This article presents a kinematic analysis of seven-degree-of-freedom serial link spatial manipulators with revolute joints. To uniquely determine the joint angles for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable that defines the angle between the arm plane and a reference plane. The forward kinematic mappings from joint space to end-effector coordinates and arm angle and the augmented Jacobian matrix that gives end-effector and arm angle rates as functions of joint rates are presented. Conditions under which the augmented Jacobian becomes singular are also given and are shown to correspond to the arm being either at a kinematically singular configuration or at a nonsingular configuration for which the arm angle ceases to parameterize the redundancy. C1 JET PROP LAB,PASADENA,CA 91109. RP KREUTZDELGADO, K (reprint author), UNIV CALIF SAN DIEGO,DEPT ECE,LA JOLLA,CA 92093, USA. NR 24 TC 60 Z9 63 U1 0 U2 8 PU MIT PRESS PI CAMBRIDGE PA 55 HAYWARD ST JOURNALS DEPT, CAMBRIDGE, MA 02142 SN 0278-3649 J9 INT J ROBOT RES JI Int. J. Robot. Res. PD OCT PY 1992 VL 11 IS 5 BP 469 EP 481 DI 10.1177/027836499201100504 PG 13 WC Robotics SC Robotics GA JR220 UT WOS:A1992JR22000004 ER PT J AU HWANG, IH MEADOR, WE AF HWANG, IH MEADOR, WE TI AN ANALYTICAL MODEL FOR LONGITUDINALLY PUMPED CONTINUOUS-WAVE LASER SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SOLID-STATE LASERS; ND-YAG LASER; DIODE; EFFICIENT; OPERATION AB An analytical model for a longitudinally end-pumped laser is developed using the circulating photon flux approach, and the threshold pump intensity and slope efficiency are expressed with the laser parameters. The thermal population in the lower laser level is included in the model. The threshold pump intensity decreases as the absorption cross section increases. The model shows that the threshold pump intensity increases as the length of the laser rod increases over the optimum value. The slope efficiency of the system depends on the laser rod length, the absorption cross section, and the reflectance of the output mirror. When the model is applied to a GaAlAs diode laser pumped Nd:YAG laser, the achievable slope efficiency reaches up to 76%, which is the ultimate quantum efficiency, at the output mirror reflectance lower than 50% with a laser crystal of loss coefficient 0.1%/cm. The experimental results of 946 nm Nd:YAG laser by Fan and Byer, Opt. Lett. 12, 809 (1987) are compared with the present model, and shows a good agreement with calculations. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HWANG, IH (reprint author), HAMPTON UNIV,DEPT PHYS,HAMPTON,VA 23668, USA. NR 11 TC 4 Z9 7 U1 1 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD OCT 1 PY 1992 VL 72 IS 7 BP 2556 EP 2561 DI 10.1063/1.351554 PG 6 WC Physics, Applied SC Physics GA JT007 UT WOS:A1992JT00700003 ER PT J AU HAKIMZADEH, R MOLLER, HJ BAILEY, SG AF HAKIMZADEH, R MOLLER, HJ BAILEY, SG TI EVALUATION OF THE MINORITY-CARRIER DIFFUSION LENGTH AND EDGE SURFACE-RECOMBINATION VELOCITY IN GAAS P/N SOLAR-CELLS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SCAN; SEM AB The hole minority carrier diffusion length (L(p)) and the edge surface-recombination velocity (V(s)) were measured as a function of distance (x) from the p-n junction in GaAs p/n concentrator solar cells. The measured V(s) values were used in a theoretical expression for the normalized electron beam-induced current. A fit of the experimental data was used to determine L(p). L(p) measured in irradiated cells showed a marked reduction as compared to the unirradiated cells. Our results were compared to results obtained in previous studies that did not account for V(s). C1 CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP HAKIMZADEH, R (reprint author), SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,2001 AEROSP PKWY,BROOK PK,OH 44142, USA. NR 13 TC 11 Z9 11 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD OCT 1 PY 1992 VL 72 IS 7 BP 2919 EP 2922 DI 10.1063/1.351494 PG 4 WC Physics, Applied SC Physics GA JT007 UT WOS:A1992JT00700052 ER PT J AU WATENPAUGH, DE YANCY, CW BUCKEY, JC LANE, LD HARGENS, AR BLOMQVIST, CG AF WATENPAUGH, DE YANCY, CW BUCKEY, JC LANE, LD HARGENS, AR BLOMQVIST, CG TI ROLE OF ATRIAL-NATRIURETIC-PEPTIDE IN SYSTEMIC RESPONSES TO ACUTE ISOTONIC VOLUME EXPANSION SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE ISOTONIC SALINE; HEMODYNAMICS; STARLING PRESSURES; BAROREFLEXES; TRANSCAPILLARY FLUID TRANSPORT; VASODILATION; DIURESIS ID VENOUS OCCLUSION METHOD; CAPILLARY-PRESSURE; DIETARY-SODIUM; HUMANS; SECRETION; INFUSION; HORMONE; POSTURE AB Atrial natriuretic peptide (ANP) may activate multiple mechanisms that protect against circulatory volume overload. We hypothesized that a temporal relationship exists between increases in cardiac filling pressure and plasma ANP concentration and also between ANP elevation and vasodilation, fluid movement from plasma to interstitium, and increased urine volume (UV). We infused 30 ml/kg isotonic saline at 100 ml/min in seven supine male subjects and monitored responses for 3 h postinfusion. Right atrial pressure (RAP) was measured via a central catheter. ANP (pmol/l) was measured by radioimmunoassay. Transcapillary fluid transport (TFT) equaled infused volume minus UV, insensible fluid loss, and change in plasma volume (PV, measured with Evan's blue). Systemic vascular resistance (SVR) was calculated as (mean arterial pressure - RAP)/cardiac output (determined by acetylene rebreathing). Plasma oncotic pressure (OP) was measured directly. During infusion, mean TFT (+/- SE) increased from net reabsorption during control of 111 +/- 27 ml/h to net filtration of 1,219 +/- 143 ml/h (P < 0.01). At end infusion, mean RAP, heart rate, and PV exhibited peak increases of 146, 23, and 27%, respectively. Concurrently, SVR and OP achieved nadirs 29 and 31% below control, respectively. Mean plasma ANP and UV peaked (45 and 390%, respectively) at 30 min postinfusion. Systemic vasodilation and capillary filtration resulted from and compensated for infusion-induced circulatory pressure increases and hemodilution. By 1 h postinfusion, most cardiovascular variables had returned toward control levels, and net reabsorption of extravascular fluid ensued. Because ANP was not significantly increased until 30 min postinfusion, it appears that factors other than ANP, such as increased vascular pressures, baroreceptor-mediated vasodilation, and hemodilution of plasma proteins, initiate responses to intravascular fluid loading. ANP may, in part, mediate the renal response to saline infusion. C1 UNIV TEXAS,SW MED CTR,DEPT INTERNAL MED,DALLAS,TX 75235. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. RP WATENPAUGH, DE (reprint author), UNIV TEXAS,SW MED CTR,DEPT PHYSIOL,DALLAS,TX 75235, USA. NR 36 TC 23 Z9 23 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 OCT PY 1992 VL 73 IS 4 BP 1218 EP 1226 PG 9 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA JV467 UT WOS:A1992JV46700002 PM 1447062 ER PT J AU MARTIN, JML AF MARTIN, JML TI ON THE PERFORMANCE OF LARGE GAUSSIAN-BASIS SETS FOR THE COMPUTATION OF TOTAL ATOMIZATION ENERGIES SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID POLARIZATION BASIS-SETS; ANHARMONIC-FORCE FIELD; COUPLED-CLUSTER METHOD; ACCURATE DETERMINATION; DISSOCIATION-ENERGIES; SUPERPOSITION ERROR; MOLECULAR-ENERGIES; TRIPLE EXCITATIONS; EQUILIBRIUM STRUCTURE; QUANTUM-CHEMISTRY AB The total atomization energies of a number of molecules have been computed using an augmented coupled-cluster method and [5s4p3d2 f1g] and [4s3p2d1f] atomic natural orbital (ANO) basis sets, as well as the correlation consistent valence triple zeta plus polarization (cc-pVTZ) and correlation consistent valence quadrupole zeta plus polarization (cc-pVQZ) basis sets. The performance of ANO and correlation consistent basis sets is comparable throughout, although the latter can result in significant CPU time savings. Whereas the inclusion of g functions has significant effects on the computed SIGMAD(e) values, chemical accuracy is still not reached for molecules involving multiple bonds. A Gaussian-1 (G1) type correction lowers the error, but not much beyond the accuracy of the G1 model itself. Using separate corrections for sigma bonds, pi bonds, and valence pairs brings down the mean absolute error to less than 1 kcal/mol for the spdf basis sets, and about 0.5 kcal/mol for the spdfg basis sets. Some conclusions on the success of the Gaussian-1 and Gaussian-2 models are drawn. C1 LIMBURGS UNIV CENTRUM, DEPT SBG, B-3590 DIEPENBEEK, BELGIUM. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV INSTELLING ANTWERP, INST MAT SCI, DEPT CHEM, B-2610 WILRIJK, BELGIUM. RI Martin, Jan/A-7457-2008 OI Martin, Jan/0000-0002-0005-5074 NR 49 TC 92 Z9 92 U1 1 U2 2 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 OCT 1 PY 1992 VL 97 IS 7 BP 5012 EP 5018 DI 10.1063/1.463855 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JR338 UT WOS:A1992JR33800045 ER PT J AU ARDANUY, PE KYLE, HL HOYT, D AF ARDANUY, PE KYLE, HL HOYT, D TI GLOBAL RELATIONSHIPS AMONG THE EARTHS RADIATION BUDGET, CLOUDINESS, VOLCANIC AEROSOLS, AND SURFACE-TEMPERATURE SO JOURNAL OF CLIMATE LA English DT Article ID OUTGOING LONGWAVE RADIATION; TERM CLIMATE VARIABILITY; SOLAR-CYCLE; ATMOSPHERIC TELECONNECTIONS; AIR-TEMPERATURE; ERB EXPERIMENT; NIMBUS-7 ERB; WIDE-FIELD; OSCILLATION; TRENDS AB The analyses of Cess are extended to consider global relationships among the earth's radiation budget (including solar insolation and changes in optically active gases), cloudiness, solar constant, volcanic aerosols, and surface temperature. Interannual variability and correlations between Nimbus-7 THIR/TOMS cloud amount, ERB WFOV longwave, shortwave, and net radiation, and SAM II aerosol optical depths, along with Hansen and Lebedeff's surface temperature analyses, are assessed. Solar luminosity is apparently related to the global surface temperature in the 1979-1990 time period based on the Nimbus-7 observations and an extended Hansen and Lebedeff temperature dataset. The 0.40-degrees-C range in observed global temperatures may be partitioned into a 0.15-degrees-C component due to a 2 W m-2 change in the solar constant and a 0.22-degrees-C component due to the increasing concentration of CO2 and other greenhouse gases. A relatively large component of the variance in the global temperature, cloudiness, and radiation budget signals is due to interannual earth system variability over time periods much shorter than a solar cycle (e.g., 2-4 years), for which the solar luminosity experiences no comparable fluctuation. The Nimbus-7 observations indicate that the global, annual cloud amount varies by +0.3% to -0.5% with a pronounced quasi-biennial periodicity and is inversely proportional to the outgoing longwave flux and surface temperature. The time dependence of aerosols injected into the stratosphere by the explosive 1982 eruption of El Chichon is found to be important, along with the global cloud amount, in describing the time dependence of the earth's albedo during the period. The sign of the relationship between the earth's surface temperature and the net radiation is of fundamental importance. The Nimbus-7 ERB net radiation observations compared to surface temperature analyses imply a stable climate (at least about some set point that is dictated by other conditions, such as the concentration of CO2 and other greenhouse gases, that do not apply over the relatively short time interval considered here). When considering future missions, we conclude that reliable and well-characterized satellite datasets with lengths of ideally one to two decades or more are required to perform quantitative analyses of the relationships among different elements of the earth's climate system. To accomplish this, the instruments' calibration should be maintained and valid to a stability that permits the analysis of interannual global fluctuations at the 0.2% level. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP ARDANUY, PE (reprint author), RES & DATA SYST CORP,SUITE 460,7855 WALKER DR,GREENBELT,MD 20770, USA. NR 41 TC 24 Z9 24 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD OCT PY 1992 VL 5 IS 10 BP 1120 EP 1139 DI 10.1175/1520-0442(1992)005<1120:GRATER>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KF433 UT WOS:A1992KF43300006 ER PT J AU MITCHELL, TP WALLACE, JM AF MITCHELL, TP WALLACE, JM TI THE ANNUAL CYCLE IN EQUATORIAL CONVECTION AND SEA-SURFACE TEMPERATURE SO JOURNAL OF CLIMATE LA English DT Article ID BAROCLINIC OCEAN MOTIONS; SEASONAL VARIABILITY; TROPICAL PACIFIC; NORTHEAST BRAZIL; ATLANTIC; MODEL; CIRCULATION; CLIMATE; DYNAMICS AB The coupled atmosphere-ocean system in the equatorial eastern Pacific and Atlantic exhibits a distinct annual cycle that is reflected in contrasting conditions at the times of the two equinoxes. The contrasts are so strong that they dominate the annual march of zonally averaged outgoing longwave radiation for the equatorial belt. The March equinox corresponds to the warm season when the equatorial cold tongues in the eastern Pacific and Atlantic are absent. With the onset of summer monsoon convection over Colombia, Central America, and West Africa in May-June, northward surface winds strengthen over the eastern Pacific and Atlantic, the equatorial cold tongues reappear, and the marine convection shifts from the equatorial belt to the intertropical convergence zones (ITCZs) along 8-degrees-N. As the northern summer progresses, the ITCZs remain strong and shift northward to near 10-degrees-N, while sea surface temperature (SST) continues to drop over the cold tongues and the southern tropics, perhaps in response to the expanding stratocumulus cloud decks in the latter region. The cold tongue-ITCZ complex persists through the September equinox, which is characterized by suppressed convection, not only over the cold tongues, but also over much of equatorial South America. On the basis of observational evidence concerning the timing and year-to-year regularity of the surface wind changes during the development of the cold tongues, it is argued that 1) the increase in the northward surface winds in response to the onset of the northern summer monsoon may be instrumental in reestablishing the cold tongues, and 2) positive feedbacks involving both the zonal and meridional wind components contribute to the remarkable robustness of the cold tongue-ITCZ complexes in both oceans. C1 UNIV WASHINGTON,DEPT ATMOSPHER SCI,SEATTLE,WA 98195. RP MITCHELL, TP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 37 TC 318 Z9 320 U1 0 U2 30 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD OCT PY 1992 VL 5 IS 10 BP 1140 EP 1156 DI 10.1175/1520-0442(1992)005<1140:TACIEC>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KF433 UT WOS:A1992KF43300007 ER PT J AU INGRALDI, AM KARIYA, TT RE, RJ PENDERGRAFT, OC AF INGRALDI, AM KARIYA, TT RE, RJ PENDERGRAFT, OC TI INTERFERENCE EFFECTS OF VERY HIGH BYPASS RATIO NACELLE INSTALLATIONS ON A LOW-WING TRANSPORT SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article AB A twin-engine, low-wing transport model, with a supercritical wing designed for a cruise Mach number of 0. 77 and a lift coefficient of 0.55, was tested in the 16-Foot Transonic Tunnel at NASA Langley Research Center. The purpose of this test was to compare the wing/nacelle interference effects of superfans (very high bypass ratio turbofans, BPR almost-equal-to 18) with the interference effects of advanced turbofans (BPR almost-equal-to 6). Flow-through nacelles were used in this study. Forces and moments on the complete model were measured using a strain gage balance and extensive surface static pressure measuements (383 orifice locations) were made on the model's wing, nacelles, and pylons. Data were taken at Mach numbers from 0.50 to 0. 80 and model angle-of-attack was varied from -4 to +8 deg. Results of the investigation indicate that superfan nacelles can be installed with approximately the same drag penalty as conventional turbofan nacelles. C1 VIGYAN RES ASSOCIATES INC,HAMPTON,VA 23666. RP INGRALDI, AM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD OCT PY 1992 VL 114 IS 4 BP 809 EP 815 DI 10.1115/1.2906661 PG 7 WC Engineering, Mechanical SC Engineering GA JV890 UT WOS:A1992JV89000029 ER PT J AU SEINER, JM MANNING, JC CAPONE, FJ PENDERGRAFT, OC AF SEINER, JM MANNING, JC CAPONE, FJ PENDERGRAFT, OC TI STUDY OF EXTERNAL DYNAMIC FLAP LOADS ON A 6-PERCENT B-1B MODEL SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article AB The origin of dynamic pressure loads on external divergent engine nozzle flaps of the B-1B aircraft was investigated in the NASA/LaRC 16-ft transonic tunnel using a 6 percent full-span model with powered engine nacelles. External flap dynamic loads and afterbody drag associated with flap removal were measured using this model. Both dry and maximum A/B power nozzles were evaluated in this study. As a result of this study, the principle mechanisms responsible for high dynamic external flap loads were determined along with performance penalty associated with flap removal. RP SEINER, JM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 10 TC 2 Z9 2 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD OCT PY 1992 VL 114 IS 4 BP 816 EP 828 DI 10.1115/1.2906662 PG 13 WC Engineering, Mechanical SC Engineering GA JV890 UT WOS:A1992JV89000030 ER PT J AU ROGERS, MM MOSER, RD AF ROGERS, MM MOSER, RD TI THE 3-DIMENSIONAL EVOLUTION OF A PLANE MIXING LAYER - THE KELVIN-HELMHOLTZ ROLLUP SO JOURNAL OF FLUID MECHANICS LA English DT Article ID STRAIGHT VORTEX FILAMENT; FREE SHEAR LAYERS; DETERMINISTIC MODELS; STREAMWISE VORTICES; TURBULENT-FLOW; SECONDARY INSTABILITY; SPANWISE STRUCTURE; STRAINED VORTICES; DYNAMICS; SCALES AB The Kelvin-Helmholtz rollup of three-dimensional temporally evolving plane mixing layers with an initial Reynolds number of 500 based on vorticity thickness and half the velocity difference have been simulated numerically. All simulations were begun from a few low-wavenumber disturbances, usually derived from linear stability theory, in addition to the mean velocity profile. A standard set of 'clean' structures develops in the majority of the simulations. The spanwise vorticity rolls up into a corrugated spanwise roller with vortex stretching creating strong spanwise vorticity in a cup-shaped region at the bends of the roller. Predominantly streamwise rib vortices develop in the braid region between the rollers. For sufficiently strong initial three-dimensional disturbances these ribs 'collapse' into compact axisymmetric vortices. The rib vortex lines connect to neighbouring ribs and are kinked in the direction opposite to that of the roller vortex lines. Because of this, these two sets of vortex lines remain distinct. For certain initial conditions, persistent ribs do not develop. In such cases, the development of significant three-dimensionality is delayed. In addition, simulations of infinitesimal three-dimensional disturbances evolving in a two-dimensional mixing layer were performed. Many features of the fully nonlinear flows are remarkably well predicted by the linear computations. Such computations can thus be used to predict the degree of three-dimensionality in the mixing layer even after the onset of nonlinearity. Several nonlinear effects can also be identified by comparing linear and nonlinear computations. These include the collapse of rib vortices, the formation of cups of spanwise vorticity. and the appearance of spanwise vorticity with sign opposite that of the mean vorticity. These nonlinear effects have been identified as precursors of the transition to turbulence (Moser & Rogers 1991). RP ROGERS, MM (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 69 TC 186 Z9 190 U1 1 U2 14 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 OCT PY 1992 VL 243 BP 183 EP 226 DI 10.1017/S0022112092002696 PG 44 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JV770 UT WOS:A1992JV77000010 ER PT J AU KAO, HC AF KAO, HC TI SOME ASPECTS OF BIFURCATION STRUCTURE OF LAMINAR-FLOW IN CURVED DUCTS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID DUAL SOLUTIONS; CROSS-SECTION; TUBE AB A bifurcation study is made of laminar flow in curved ducts. The problem is formulated in a curvilinear coordinate system, and the governing equations, after orthogonal mapping is applied, are solved numerically by an iterative finite-difference method. Many computer runs were made with various duct cross-sections ranging from a circle to a square, to learn the transition of bifurcation structure with this change in cross-section and to reconcile the differences between them. In addition, a simpler technique is proposed to generate symmetric four-cell solutions in a circular pipe and a means is put forward to stabilize four-vortex structures in a complete cross-section. RP KAO, HC (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 23 TC 16 Z9 16 U1 0 U2 2 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 OCT PY 1992 VL 243 BP 519 EP 539 DI 10.1017/S0022112092002805 PG 21 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JV770 UT WOS:A1992JV77000021 ER PT J AU GLAZMAN, RE AF GLAZMAN, RE TI MULTIWAVE INTERACTION THEORY FOR WIND-GENERATED SURFACE GRAVITY-WAVES SO JOURNAL OF FLUID MECHANICS LA English DT Article ID EQUILIBRIUM RANGE; DEVELOPED SEA; GEOMETRY; SLOPE; FIELD AB Consistently employing the assumption of localness of wave-wave interactions in the wavenumber space, the Kolmogorov treatment of the energy cascade is applied to the case of wind-generated surface gravity waves. The effective number nu of resonantly interacting wave harmonics is not limited to four but is found as a solution of a coupled system of equations expressing: (i) the dependence of the spectrum shape on the degree of the wave nonlinearity, and (ii) the continuity of the wave action flux through the spectrum given a continuous positive input from wind. The latter is specified in a Miles-type fashion, and a simple scaling relationship based on the concept of the turnover time is derived in place of the kinetic equation. The mathematical problem is reduced to an ordinary differential equation of first order. The exponent in the 'power law' for the spectral density of the wave potential energy and the effective number of resonantly interacting wave harmonics are found as functions of the wave frequency and of external factors of wind-wave interaction. The solution is close to the Zakharov-Filonenko spectrum at low frequencies and low wind input while approaching the Phillips spectrum at high frequencies and sufficiently high wind. RP GLAZMAN, RE (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 27 TC 4 Z9 4 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 OCT PY 1992 VL 243 BP 623 EP 635 DI 10.1017/S0022112092002854 PG 13 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JV770 UT WOS:A1992JV77000026 ER PT J AU LOCKWOOD, M SMITH, MF AF LOCKWOOD, M SMITH, MF TI THE VARIATION OF RECONNECTION RATE AT THE DAYSIDE MAGNETOPAUSE AND CUSP ION PRECIPITATION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FLUX-TRANSFER EVENTS; LOW-ALTITUDE SIGNATURES; INTERPLANETARY MAGNETIC-FIELD; PLASMA INJECTION; BOUNDARY-LAYER; MAGNETOSPHERE; CONVECTION; MAGNETOMETER; IONOSPHERE; REGION AB A method is presented which allows estimation of the variation of the rate of magnetic reconnection at the dayside magnetopause. This is achieved using observations of the cusp particle precipitation made by low-altitude polar-orbiting spacecraft. In this paper we apply the technique to a previously published example of a cusp intersection by the DMSP F7 satellite. It is shown that the cusp signature in this case was produced by three separate bursts of reconnection which were of the order of 10 min apart, each lasting roughly 1 min. This is similar to the variation of reconnection rate which is required to explain typical flux transfer event signatures at the magnetopause. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,LONDON SW7 2AZ,ENGLAND. RP LOCKWOOD, M (reprint author), RUTHERFORD APPLETON LAB,DEPT SPACE SCI,R25,ROOM 1-04,DIDCOT OX11 0QX,OXON,ENGLAND. RI Lockwood, Mike/G-1030-2011 OI Lockwood, Mike/0000-0002-7397-2172 NR 42 TC 156 Z9 156 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1992 VL 97 IS A10 BP 14841 EP 14847 DI 10.1029/92JA01261 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR009 UT WOS:A1992JR00900005 ER PT J AU LIN, N ENGEBRETSON, MJ REINLEITNER, LA OLSON, JV GALLAGHER, DL CAHILL, LJ SLAVIN, JA PERSOON, AM AF LIN, N ENGEBRETSON, MJ REINLEITNER, LA OLSON, JV GALLAGHER, DL CAHILL, LJ SLAVIN, JA PERSOON, AM TI FIELD AND THERMAL PLASMA OBSERVATIONS OF ULF PULSATIONS DURING A MAGNETICALLY DISTURBED INTERVAL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID KELVIN-HELMHOLTZ INSTABILITY; COMPRESSIONAL PC-5 WAVE; GEOMAGNETIC-FIELD; SOLAR-WIND; LINE RESONANCES; DAYSIDE MAGNETOSPHERE; STANDING WAVES; OSCILLATIONS; MAGNETOPAUSE; MAGNETOSHEATH AB ULF pulsations were observed by DE 1 between 1600 and 1830 UT, October 31, 1982, during a magnetically disturbed interval. Ground observations suggested that the pulsations were excited by a sudden increase in the solar wind velocity and pressure. During the pulsation interval DE 1 traveled near apogee from -55 to -20-degrees geomagnetic latitude and from L approximately 13 to L approximately 4 at about 0900 LT. The waves observed were azimuthal oscillations preceded by gradually decaying long period compressional waves which lasted for more than 1 hour. Phase relations between magnetic and electric field oscillations and calculated Poynting flux indicate that in the outer magnetosphere (L > 8) DE 1 observed propagating waves which contained strong poloidal components, while the quasi-sinusoidal toroidal waves seen later for L < 10.3 were standing along field lines. The toroidal waves appeared as four wave packets, each of which corresponded to a region with a distinct plasma distribution. The observed wave periods decreased with L over an extended magnetospheric region. The seemingly weak interaction between magnetic shells suggests that the source was a broadband one. Magnetometer data from several high latitude observatories located near the footpoints of the magnetic shells crossed by DE 1 were also examined. The magnetic pulsations on the ground contained many frequency components, and the waves seen most strongly in space were often not the strongest signals seen on the ground near the same field lines. The broadband nature of the ground pulsations indicates that the stations also detected oscillations of the adjacent field lines. The major frequencies seen at ground stations seemed to be roughly constant for about 2 hours but L dependent. This suggests that the changing periods seen in space by DE 1 were clearly L related and not temporally varying. C1 AUGSBURG COLL,DEPT PHYS,MINNEAPOLIS,MN. NW RES ASSOCIATES INC,BELLEVUE,WA 98009. UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99701. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 42 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1992 VL 97 IS A10 BP 14859 EP 14875 DI 10.1029/92JA00315 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR009 UT WOS:A1992JR00900007 ER PT J AU BOARDSEN, SA GALLAGHER, DL GURNETT, DA PETERSON, WK GREEN, JL AF BOARDSEN, SA GALLAGHER, DL GURNETT, DA PETERSON, WK GREEN, JL TI FUNNEL-SHAPED, LOW-FREQUENCY EQUATORIAL WAVES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DISTRIBUTIONS; PLASMA AB Funnel-shaped, low-frequency radiation, as observed in frequency time spectrograms, are frequently found at the Earth's magnetic equator. At the equator the radiation often extends from the proton cyclotron frequency up to the lower hybrid frequency. Ray-tracing calculations can qualitatively reproduce the observed frequency-time characteristics of these emissions if the waves am propagating in the fast magnetosonic mode starting with wave normal angles of approximately 88-degrees at the magnetic equator. The funnel-shaped emissions are consistent with generation by protons with a ring-type velocity space distribution. A ring-shaped region of positive slope in the velocity space density distribution of protons is observed near the Alfven velocity, indicating that the ring protons strongly interact with the waves. Ray-tracing calculations show that for similar equatorial wave normal angles lower-frequency fast magnetosonic waves are more closely confined to the magnetic equator than higher-frequency fast magnetosonic waves. For waves refracted back toward the equator at similar magnetic latitudes, the lower-frequency waves experience stronger damping in the vicinity of the equator than higher-frequency waves. Also, wave growth is restricted to higher frequencies at larger magnetic latitudes. Wave damping at the equator and wave growth off the equator favors equatorial wave normal angle distributions which lead to the funnel-shaped frequency time characteristic. C1 UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LOCKHEED MISSILES & SPACE CO INC,SPACE SCI LAB,PALO ALTO,CA 94204. RP BOARDSEN, SA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. RI Peterson, WK/A-8706-2009 OI Peterson, WK/0000-0002-1513-6096 NR 17 TC 63 Z9 63 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 OCT 1 PY 1992 VL 97 IS A10 BP 14967 EP 14976 DI 10.1029/92JA00827 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR009 UT WOS:A1992JR00900017 ER PT J AU WHITTENBERGER, JD LUTON, MJ AF WHITTENBERGER, JD LUTON, MJ TI ELEVATED-TEMPERATURE COMPRESSIVE PROPERTIES OF REACTION MILLED NIAL-ALN AND ZR-DOPED NIAL-ALN COMPOSITES SO JOURNAL OF MATERIALS RESEARCH LA English DT Article AB Previous studies of a single lot of NiAl powder which had been ground under high intensity conditions in liquid nitrogen (cryomilling) indicated that this processing leads to a high strength, elevated temperature NiAl-AlN composite. Because this was the first known example of the use of the reaction milling process to produce a high temperature composite, the reproducibility of this technique was unknown. Two additional lots of NiAl powder and a lot of a Zr-doped NiAl powder have been cryomilled, and analyses indicate that AlN was formed within a NiAl matrix in all three cases. Compression testing between 1200 K and 1400 K has shown that the deformation resistance of these heats is similar to that of the first lot of NiAl-AlN; thus cryomilling can improve the creep resistance of NiAl by a factor of six. Based on this work, it is concluded that cryomilling of NiAl powder to form high temperature, high strength NiAl-AlN composites is a reproducible process. C1 EXXON RES & ENGN CO,ANNANDALE,NJ 08801. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 9 TC 11 Z9 12 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 OCT PY 1992 VL 7 IS 10 BP 2724 EP 2732 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA JR170 UT WOS:A1992JR17000011 ER PT J AU BAYARD, DS AF BAYARD, DS TI REDUCED COMPLEXITY DYNAMIC-PROGRAMMING BASED ON POLICY ITERATION SO JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS LA English DT Article ID SYSTEMS; DESIGN RP BAYARD, DS (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 28 TC 14 Z9 17 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 0022-247X EI 1096-0813 J9 J MATH ANAL APPL JI J. Math. Anal. Appl. PD OCT PY 1992 VL 170 IS 1 BP 75 EP 103 DI 10.1016/0022-247X(92)90007-Z PG 29 WC Mathematics, Applied; Mathematics SC Mathematics GA JU669 UT WOS:A1992JU66900006 ER PT J AU DEVI, VM BENNER, DC SMITH, MAH RINSLAND, CP AF DEVI, VM BENNER, DC SMITH, MAH RINSLAND, CP TI MEASUREMENTS OF PRESSURE BROADENING AND PRESSURE SHIFTING BY NITROGEN IN THE NU-1 AND NU-3 BANDS OF H-2 O-16 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID N-2-BROADENED HALFWIDTHS; WATER-VAPOR; AIR; H2O; COEFFICIENTS; LINES; INTENSITIES; ABSORPTION; ROTATION; SPECTRA C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP DEVI, VM (reprint author), COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23187, USA. NR 21 TC 14 Z9 14 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD OCT PY 1992 VL 155 IS 2 BP 333 EP 342 PG 10 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA JP527 UT WOS:A1992JP52700009 ER PT J AU TOLMAN, HL AF TOLMAN, HL TI EFFECTS OF NUMERICS ON THE PHYSICS IN A 3RD-GENERATION WIND-WAVE MODEL SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID FLUX-CORRECTED TRANSPORT; GRAVITY-WAVES; ALGORITHMS; SPECTRUM AB Numerical errors in third-generation ocean wave models can result in a misinterpretation of the physics in the model. Using idealized situations, it is shown that numerical errors significantly influence the initial growth, the response of wave fields to turning winds, the scaling behavior of model results with wind speed, and the propagation of swell. Furthermore. the numerics may influence the dynamic interaction between wind sea and swell. Surprisingly, fetch-limited model behavior is hardly influenced by numerical errors in wave propagation. Simple modifications of the numerics are presented to reduce or eliminate such errors. The impact of numerical improvements for realistic conditions is illustrated by performing hindcasts for the Atlantic basin and for a smaller region off the east coast of the United States. RP NASA, GODDARD SPACE FLIGHT CTR, OCEANS LAB, CODE 9104, GREENBELT, MD 20771 USA. NR 27 TC 83 Z9 87 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-3670 EI 1520-0485 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD OCT PY 1992 VL 22 IS 10 BP 1095 EP 1111 DI 10.1175/1520-0485(1992)022<1095:EONOTP>2.0.CO;2 PG 17 WC Oceanography SC Oceanography GA JU785 UT WOS:A1992JU78500002 ER PT J AU YIN, FL FUNG, IY CHU, CK AF YIN, FL FUNG, IY CHU, CK TI EQUILIBRIUM RESPONSE OF OCEAN DEEP-WATER CIRCULATION TO VARIATIONS IN EKMAN PUMPING AND DEEP-WATER SOURCES SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID WORLD OCEAN; VENTILATED THERMOCLINE; MODEL; DRIVEN; THERMOHALINE; RADIOCARBON; SENSITIVITY; INTERIOR; SEA AB A multilayer ocean model that is physically simple and computationally efficient is developed for studies of competition and interaction among deep-water sources in determining ocean circulation. The model is essentially geostrophic and hydrostatic in the ocean interior with Rayleigh friction added in boundary-layer and equatorial regions. A stably stratified density structure is specified at static equilibrium, and cross-isopycnal mixing is parameterized as a diffusive flux. The model is forced by latitudinally varying Ekman pumping velocities at the base of the ocean surface Ekman layer and localized deep-water sources. A four-layer version of the model has been run in a rectangular basin with 5000-m depth, extending from 65-degrees-S to 65-degrees-N latitude and covering 70 degrees of longitude. The four layers mimic the major water masses observed in the Atlantic Ocean: thermocline water. intermediate water, North Atlantic Deep Water (NADW), and Antarctic Bottom Water (AABW). For forcing corresponding to the current climate, warm water and cold water circulation routes produced in the model agree with those inferred from observations, for example, southward-flowing NADW overriding northward-flowing AABW in the western boundary. The model shows that subtropical gyres intensify, and thermocline depths become shallow, when deep-water formation rates increase, or when vertical diffusivity k(upsilon) decreases, or when more NADW is formed from the thermocline layer than that from the intermediate layer. Consistent with the advective thermocline depth scaling, distributions of the Ekman pumping contribute little to deep-water circulations. The interaction between NADW and AABW sources is demonstrated. Changes in the formation rate of a deep-water source alter cross-isopycnal flows, especially along the related circulation route, thus altering the extent that the other sources can travel before they detrain significantly. These changes feed back onto the thermocline circulation and cross-equatorial transports. The model suggests that reduction in deep-water formation rate may increase the transient response time of the atmosphere to perturbations, because the thermocline depth becomes deeper. Also, poleward heat transport may decrease, thus acting to self-regulate the temperatures in polar regions C1 COLUMBIA UNIV,DEPT APPL PHYS,NEW YORK,NY 10027. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,GREENBELT,MD 20771. NR 41 TC 3 Z9 3 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD OCT PY 1992 VL 22 IS 10 BP 1129 EP 1157 DI 10.1175/1520-0485(1992)022<1129:EROODW>2.0.CO;2 PG 29 WC Oceanography SC Oceanography GA JU785 UT WOS:A1992JU78500004 ER PT J AU KUMAR, N SRIVASTAVA, KM KUMAR, V AF KUMAR, N SRIVASTAVA, KM KUMAR, V TI EFFECT OF LARGE LARMOR RADIUS ON THE STABILITY OF AN INFINITELY CONDUCTING INHOMOGENEOUS-PLASMA SO JOURNAL OF PLASMA PHYSICS LA English DT Article ID MAGNETICALLY STRUCTURED ATMOSPHERE; ALFVEN-WAVE; SURFACE-WAVES; RESONANT ABSORPTION; BENDING WAVES; PROPAGATION; SHEET; SLAB AB The effect of a large Larmor radius on the stability of an infinitely conducting infinitely extended inhomogeneous plasma with two-dimensional magnetic field has been studied. A dispersion relation is obtained for the homogeneous system, and it is found that it is stable and MHD waves propagate. For an inhomogeneous plasma, a dispersion relation is also obtained and discussed for disturbances propagating transverse to inhomogeneity in (a) a cold plasma and (b) an incompressible plasma. It is found that the inhomogeneous system is unstable in both the cases, in agreement with the results of Lee and Roberts. The values of omega(r) and omega(i) are computed numerically, and the variations of omega(i) > 0 and the corresponding omega(r) with the large-Larmor-radius parameter are shown graphically. C1 JET PROP LAB,PASADENA,CA 91109. RP KUMAR, N (reprint author), UNIV ROORKEE,DEPT MATH,ROORKEE 247667,UTTAR PRADESH,INDIA. NR 28 TC 0 Z9 0 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-3778 J9 J PLASMA PHYS JI J. Plasma Phys. PD OCT PY 1992 VL 48 BP 245 EP 260 PN 2 PG 16 WC Physics, Fluids & Plasmas SC Physics GA KD940 UT WOS:A1992KD94000006 ER PT J AU HINKLEY, JA EFTEKHARI, A CROOK, RA JENSEN, BJ SINGH, JJ AF HINKLEY, JA EFTEKHARI, A CROOK, RA JENSEN, BJ SINGH, JJ TI FREE-VOLUME IN GLASSY POLY(ARYLENE ETHER KETONE)S SO JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS LA English DT Article DE FREE VOLUME IN GLASSY POLY(ARYLENE ETHER KETONES)S; GLASSY POLYMERS, FREE VOLUME IN; POLY(ARYLENE ETHER KETONE)S, FREE VOLUME IN ID RELAXATION; POLYMERS; LIFETIME AB Amorphous polyarylene ether ketones were examined in the glassy state by positron annihilation lifetime spectroscopy (PALS) and in the melt by standard rheological techniques. Specimens were well-characterized fractions of two isomeric structures. PALS clearly shows that the polymer with meta linkages in its backbone contains larger voids (> 0.25 nm radius). Thus despite their similar bulk densities, the two materials must pack very differently on a local scale. On the other hand, the free volumes inferred from the WLF treatment of melt viscosity data are practically identical in both materials ca. 4% at T(g). The comparison between techniques sheds some light on the distribution of free volume. C1 HAMPTON UNIV,HAMPTON,VA 23666. TEXAS A&M UNIV SYST,COLL STN,TX 77843. RP HINKLEY, JA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 16 TC 13 Z9 14 U1 0 U2 4 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-6266 J9 J POLYM SCI POL PHYS JI J. Polym. Sci. Pt. B-Polym. Phys. PD OCT PY 1992 VL 30 IS 11 BP 1195 EP 1198 DI 10.1002/polb.1992.090301103 PG 4 WC Polymer Science SC Polymer Science GA JL869 UT WOS:A1992JL86900003 ER PT J AU OH, JJ COHEN, EA AF OH, JJ COHEN, EA TI PRESSURE BROADENING OF OZONE LINES NEAR 184 AND 206 GHZ BY NITROGEN AND OXYGEN SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID TEMPERATURE-DEPENDENCE; HALFWIDTHS; LINEWIDTHS; SHIFTS AB The N2 and O2 pressure broadenings of the two O3 transitions, which are used for satellite monitoring of upper atmospheric O3, have been measured between 200 and 300 K. The derived air-broadening coefficients are accurate within 3% over the entire temperature range. C1 JET PROP LAB,PASADENA,CA 91109. NR 14 TC 20 Z9 20 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD OCT PY 1992 VL 48 IS 4 BP 405 EP 408 DI 10.1016/0022-4073(92)90059-D PG 4 WC Optics; Spectroscopy SC Optics; Spectroscopy GA JQ799 UT WOS:A1992JQ79900005 ER PT J AU GOORVITCH, D GALANT, DC AF GOORVITCH, D GALANT, DC TI SOLUTION OF THE SCHRODINGER-EQUATION FOR A DOUBLE MINIMUM POTENTIAL SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Note ID EIGENVALUE AB We apply Richardson's extrapolation to zero mesh size to calculate the dissociation energies and wavefunctions of a double minimum potential curve for the E,F1SIGMA(g)+ state of H-2. We demonstrate that a double minimum potential presents no difficulties and that this extrapolation method is to be preferred over a quadratic extrapolation or the use of a basis expansion. C1 NASA,AMES RES CTR,DIV INFORMAT SYST,MOFFETT FIELD,CA 94035. RP GOORVITCH, D (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 7 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 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD OCT PY 1992 VL 48 IS 4 BP 467 EP 468 DI 10.1016/0022-4073(92)90064-B PG 2 WC Optics; Spectroscopy SC Optics; Spectroscopy GA JQ799 UT WOS:A1992JQ79900010 ER PT J AU SRINIVASAN, K JACKSON, WC SMITH, BT HINKLEY, JA AF SRINIVASAN, K JACKSON, WC SMITH, BT HINKLEY, JA TI CHARACTERIZATION OF DAMAGE MODES IN IMPACTED THERMOSET AND THERMOPLASTIC COMPOSITES SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article AB Composite materials remain extremely vulnerable to out-of-plane impact loads, which may lead to severe losses in strength and stiffness. Impact induced damage is often a complex mixture of transverse cracks, delaminations and fiber failures. An experimental investigation was undertaken to quantify damage tolerance and resistance in composite materials impacted using the drop-weight method. Tests were conducted on laminates of several different carbon-fiber composite systems such as epoxies, modified epoxies, and amorphous and semicrystalline thermoplastics. In this paper, impacted composite specimens have been examined using destructive and nondestructive techniques to establish the characteristic damage states. Specifically, optical microscopy, ultrasonic and scanning electron microscopy techniques have been used to identify impact induced damage mechanisms. Damage propagation during post impact compression was also studied. C1 NASA,LANGLEY RES CTR,USA AEROSTRUCT DIRECTORATE,HAMPTON,VA 23665. COLL WILLIAM & MARY,WILLIAMSBURG,VA 23185. NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23665. RP SRINIVASAN, K (reprint author), OLD DOMINION UNIV,DEPT MECH ENGN & MECH,NORFOLK,VA 23529, USA. NR 6 TC 24 Z9 25 U1 0 U2 4 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 OCT PY 1992 VL 11 IS 10 BP 1111 EP 1126 DI 10.1177/073168449201101004 PG 16 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA JQ964 UT WOS:A1992JQ96400004 ER PT J AU TAUSWORTHE, RC AF TAUSWORTHE, RC TI INFORMATION MODELS OF SOFTWARE PRODUCTIVITY - LIMITS ON PRODUCTIVITY GROWTH SO JOURNAL OF SYSTEMS AND SOFTWARE LA English DT Article ID SCIENCE AB This article reports research into generalized information-metric models of software process productivity to establish quantifiable behavior and theoretical bounds. The models establish a fundamental mathematical relationship between software productivity and the human capacity for information traffic, the software product yield (system size), information efficiency, and tool and process efficiencies. The article then derives an upper bound that quantifies average software productivity and the maximum rate at which it may grow. This bound reveals that, ultimately, when tools, methodologies, and automated assistants have reached their maximum effective state, further improvement in productivity can only be achieved through increasing software reuse. The reuse advantage is shown not to increase faster than logarithmically in the number of reusable features available. The reuse bound is further shown to be somewhat dependent on the reuse policy: a general "reuse everything" policy can lead to a somewhat slower productivity growth than a specialized reuse policy. C1 JET PROP LAB,DIV INFORMAT SYST,PASADENA,CA 91109. NR 27 TC 1 Z9 1 U1 1 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0164-1212 J9 J SYST SOFTWARE JI J. Syst. Softw. PD OCT PY 1992 VL 19 IS 2 BP 185 EP 201 DI 10.1016/0164-1212(92)90070-Z PG 17 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA JN793 UT WOS:A1992JN79300010 ER PT J AU WIEDLOCHER, DE TUCKER, DS NICHOLS, R KINSER, DL AF WIEDLOCHER, DE TUCKER, DS NICHOLS, R KINSER, DL TI LOW-EARTH-ORBIT EFFECTS ON STRENGTH OF GLASSES SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Note ID RADIATION AB The effects of a 5.8-y exposure to low-earth-orbit environment upon the mechanical properties of five commercial glasses and a low-expansion-coefficient glass-ceramic have been examined. The radiation components of the earth-orbit environment did not degrade the mechanical strength of the samples examined within the limits of experimental error. Statistical problems arising from the low frequency of micrometeorite or space debris impacts upon the samples precluded statistically valid measurement of impacted sample strengths. Upper bounds for the magnitude of the impact event damage upon the strengths for impacted samples have been determined. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP WIEDLOCHER, DE (reprint author), VANDERBILT UNIV,DEPT MAT SCI & ENGN,NASHVILLE,TN 37235, USA. NR 9 TC 3 Z9 3 U1 0 U2 1 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD OCT PY 1992 VL 75 IS 10 BP 2893 EP 2895 DI 10.1111/j.1151-2916.1992.tb05527.x PG 3 WC Materials Science, Ceramics SC Materials Science GA JT351 UT WOS:A1992JT35100047 ER PT J AU SMITH, PN AF SMITH, PN TI FLIGHT DATA ACQUISITION FOR VALIDATION OF PASSIVE RANGING ALGORITHMS FOR OBSTACLE AVOIDANCE SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB The automation of low-altitude rotorcraft flight depends on the ability to detect, locate, and navigate around obstacles lying in the rotorcraft's intended flightpath. Computer vision techniques provide a passive method of obstacle detection and range estimation, for obstacle avoidance. Several algorithms based on computer vision methods have been developed for this purpose using laboratory data; however, further development and validation of candidate algorithms require data collected from rotorcraft flight. A data base containing low-altitude imagery augmented with the rotorcraft and sensor parameters required for passive range estimation is not readily available. This paper focuses on the methodology used to develop such a data base from flight-test data consisting of imagery, rotorcraft and sensor parameters, and ground-truth range measurements. As part of the data preparation, a technique for obtaining the sensor calibration parameters is described. The data base will enable the further development of algorithms for computer vision-based obstacle detection and passive range estimation, as well as provide a benchmark for verification of range estimates against ground-truth measurements. RP SMITH, PN (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1992 VL 37 IS 4 BP 32 EP 37 PG 6 WC Engineering, Aerospace SC Engineering GA JU678 UT WOS:A1992JU67800005 ER PT J AU FELKER, FF AF FELKER, FF TI WING DOWNLOAD RESULTS FROM A TEST OF A 0.658-SCALE V-22 ROTOR AND WING SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB A test of a 0.658-scale V-22 rotor and wing was conducted in the 40 x 80 Foot Wind Tunnel at Ames Research Center. One of the principal objectives of the test was to measure the wing download in hover for a variety of test configurations. The wing download and surface pressures were measured for a wide range of thrust coefficients, with five different flap angles, two nacelle angles, and both directions of rotor rotation. This paper presents these results, and describes a new method for interpreting wing surface pressure data in hover. This method shows that the wing nap can produce substantial lift loads in hover. RP FELKER, FF (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 12 TC 8 Z9 8 U1 0 U2 1 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1992 VL 37 IS 4 BP 58 EP 63 PG 6 WC Engineering, Aerospace SC Engineering GA JU678 UT WOS:A1992JU67800008 ER PT J AU MULLINS, LD AF MULLINS, LD TI INITIAL-VALUE AND 2 POINT BOUNDARY-VALUE SOLUTIONS TO THE CLOHESSY-WILTSHIRE EQUATIONS SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB The nonhomogeneous Clohessy-Wiltshire (C-W) equations are formulated and solved as an initial value problem in the formal structure of linear systems theory. The nonhomogeneous C-W equations could have many conceivable forcing functions but one useful in many satellite studies, that of constant differential drag (or of constant low level thrusting) along or opposite the velocity vector, is assumed in this paper. The state transition matrix (STM) (obtained from the solution of the homogeneous C-W equations) and its inverse (required to solve the general nonhomogeneous set of equations in this theory) are obtained explicitly in both Newtonian and Hamiltonian form. In general, the analytic inverse of a 6 X 6 matrix is not easily constructed unless that matrix possesses some special symmetry property such as being orthogonal or symplectic. It is shown that the STM for the C-W equations does possess a special property making its inverse easily obtainable. To construct an effective mission design tool for orbit transfers, the C-W solutions also need to be available in the form of a two-point boundary value problem; therefore, the initial value solutions, obtained via the STM and its inverse, are recast with relative ease as closed-form solutions to a Lambert problem. The initial value solutions are free of singularities but the Lambert solutions possess isolated singularities which are identified. RP MULLINS, LD (reprint author), MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 8 TC 12 Z9 13 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1992 VL 40 IS 4 BP 487 EP 501 PG 15 WC Engineering, Aerospace SC Engineering GA KK273 UT WOS:A1992KK27300004 ER PT J AU WU, JT WU, SC AF WU, JT WU, SC TI INCORPORATION OF A PRIORI GRAVITY-FIELD INFORMATION IN SATELLITE ORBIT DETERMINATION USING BIN PARAMETERS SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article ID PRECISE AB A method to determine satellite orbits using tracking data and a priori gravitational field is described. The a priori constraint on the orbit dynamics is determined by the covariance matrix of the spherical harmonic coefficients for the gravity model, so that the optimal combination of the measurements and gravitational field is achieved. A set of bin parameters is introduced to represent the perturbation of the gravitational field on the position of the satellite orbit. The covariance matrix of a conventional gravity model is transformed into that for the bin parameters by the variational partial derivatives. The covariance matrices of the bin parameters and the epoch state are combined to form the covariance matrix of the satellite positions at the measurement times. The combined matrix is used as the a priori information to estimate the satellite positions with measurements. RP WU, JT (reprint author), JET PROP LAB,TRACKING SYST & APPLICAT SECT,PASADENA,CA 91109, USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1992 VL 40 IS 4 BP 547 EP 555 PG 9 WC Engineering, Aerospace SC Engineering GA KK273 UT WOS:A1992KK27300007 ER PT J AU LUCKE, RL SIRLIN, SW SANMARTIN, AM AF LUCKE, RL SIRLIN, SW SANMARTIN, AM TI NEW DEFINITIONS OF POINTING STABILITY - AC AND DC EFFECTS SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB For most imaging sensors, a constant (DC) pointing error is unimportant (unless large!), but time-dependent (AC) errors degrade performance by either distorting or smearing the image. When properly quantified, the separation of the root-mean-square effects of random line-of-sight motions into DC and AC components can be used to obtain the minimum necessary line-of-sight stability specifications. The relation between stability requirements and sensor resolution is discussed, with a view to improving communication between the data analyst and the control systems engineer. C1 JET PROP LAB,PASADENA,CA 91109. RP LUCKE, RL (reprint author), USN,RES LAB,CODE 7604,WASHINGTON,DC 20375, USA. NR 18 TC 11 Z9 12 U1 2 U2 6 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 OCT-DEC PY 1992 VL 40 IS 4 BP 557 EP 576 PG 20 WC Engineering, Aerospace SC Engineering GA KK273 UT WOS:A1992KK27300008 ER PT J AU PLUMB, RA HOU, AY AF PLUMB, RA HOU, AY TI THE RESPONSE OF A ZONALLY SYMMETRICAL ATMOSPHERE TO SUBTROPICAL THERMAL FORCING - THRESHOLD BEHAVIOR SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID STEADY-STATE MODELS; BASIC STATE; INSTABILITY; CIRCULATIONS; CLIMATE AB We consider the response of a zonally symmetric atmosphere to a thermal forcing that is localized in the subtropics. Specifically, the equilibrium temperature distribution has a local subtropical peak and is flat elsewhere, including at the equator. On the basis of inviscid steady-state theory, it is argued that the response to such forcing is one of two distinct types. Below a threshold forcing the atmosphere adopts a steady state of thermal equilibrium with no meridional flow. With supercritical forcing, this state breaks down and a strong meridional circulation is predicted. The threshold forcing value is that at which the absolute vorticity of the zonal flow (in gradient balance with the equilibrium temperatures) vanishes at the upper boundary. These inviscid predictions are tested in a zonally symmetric numerical model; while the model viscosity shifts the threshold and otherwise modifies the response, the threshold is clearly evident in the model behavior. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP PLUMB, RA (reprint author), MIT,CTR METEOROL & PHYS OCEANOG,ROOM 54-1726,CAMBRIDGE,MA 02139, USA. RI Hou, Arthur/D-8578-2012 NR 10 TC 93 Z9 98 U1 1 U2 5 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 OCT 1 PY 1992 VL 49 IS 19 BP 1790 EP 1799 DI 10.1175/1520-0469(1992)049<1790:TROAZS>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JR568 UT WOS:A1992JR56800002 ER PT J AU KALU, EE WHITE, RE DARCY, EC AF KALU, EE WHITE, RE DARCY, EC TI CALORIMETRIC DETERMINATION OF THE THERMONEUTRAL POTENTIAL OF LI/BCX AND LI/SOCL2 CELLS SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article AB Through a continuous recording of the cell voltage, heat flow, and current, the effective thermoneutral potential, E(etp) of Li/BCX and Li/SOCl2 cells were determined in the temperature range, 0-60-degrees-C. The depth of discharge (DOD), temperature (T), and cell type (cell chemistry) affect the effective thermoneutral potential. The effective thermoneutral potential, E(etp) differs from the classical thermoneutral potential of a cell because it takes into account the heat flow due to non-faradaic processes. The average effective thermoneutral potential at 25-degrees-C (determined by selecting the most constant region of E(etp) vs. time of discharge) was 4.0 and 3.84 V for BCX and Li/SOCl2 cells, respectively. Based on the classical approach, the reversible cell potential, E(r) and temperature dependence of reversible cell potential, dE(r)/dT for BCX cell were 3.74 V and -0.852 mV/K, respectively, and for Li/SOCl2, E(r) = 3.67 V and dE(r)/dT = -0.567 mV/K. The thermal polarization (E(etp) - E(l)), where E(l) is the load voltage, for both cells, showed that they are most thermally efficient near 40-degrees-C. A measure of the heat flow for both cells at 50% DOD supports this observation. An overall reaction proposed for the BCX chemistry is supported by the calculated thermodynamic parameters. C1 TEXAS A&M UNIV SYST,DEPT CHEM ENGN,CTR ELECTROCHEM ENGN,COLL STN,TX 77843. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 13 TC 2 Z9 2 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 OCT PY 1992 VL 139 IS 10 BP 2755 EP 2759 DI 10.1149/1.2068975 PG 5 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA JR764 UT WOS:A1992JR76400013 ER PT J AU BARNES, NP PETWAY, LB AF BARNES, NP PETWAY, LB TI VARIATION OF THE VERDET CONSTANT WITH TEMPERATURE OF TERBIUM GALLIUM GARNET SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article AB A measurement of the variation of the Verdet constant of terbium gallium garnet as a function of temperature was made for visible and near-infrared wavelengths. By combining results of the angle of rotation presented here with previously published absolute measurements, we determined the Verdet constant as a function of wavelength for wavelengths extending from about 0.5 to 1.1 mum. Data correlated well with paramagnetic models. Such information is necessary to determine the angle of rotation as well as the variation of the extinction ratio of a Faraday isolator with temperature. C1 HAMPTON UNIV,HAMPTON,VA 23668. RP BARNES, NP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 3 TC 42 Z9 43 U1 0 U2 16 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3224 J9 J OPT SOC AM B JI J. Opt. Soc. Am. B-Opt. Phys. PD OCT PY 1992 VL 9 IS 10 BP 1912 EP 1915 DI 10.1364/JOSAB.9.001912 PG 4 WC Optics SC Optics GA JR872 UT WOS:A1992JR87200020 ER PT J AU SPUCKLER, CM SIEGEL, R AF SPUCKLER, CM SIEGEL, R TI REFRACTIVE-INDEX EFFECTS ON RADIATIVE BEHAVIOR OF A HEATED ABSORBING-EMITTING LAYER SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Temperature distributions and other heat transfer characteristics are analyzed for a heated plane layer of Semitransparent material with refractive index greater-than-or-equal-to 1. The analysis includes heat conduction, emission, and absorption within the layer. The layer has diffuse interfaces; examples are a frosted quartz window used to diffuse incident radiation in high temperature surroundings, or a ceramic layer with small scattering used in high-temperature applications. Each side of the layer is heated by radiation and convection, and interface reflections are included. When the index of refraction is larger than unity, there are total internal reflections of some of the energy within the layer. This has a substantial effect on distributing energy across the layer, and considerably alters the temperature distribution from when the refractive index is unity. Results are given for a gray layer and for a two-band spectral variation of the absorption coefficient. Radiant energy leaving the surface was examined to determine when it could be used to measure surface temperature accurately. C1 NASA, LEWIS RES CTR, HEAT TRANSFER BRANCH, CLEVELAND, OH 44135 USA. NR 14 TC 33 Z9 33 U1 1 U2 4 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 EI 1533-6808 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1992 VL 6 IS 4 BP 596 EP 604 DI 10.2514/3.11539 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JW316 UT WOS:A1992JW31600003 ER PT J AU CORNELISON, CJ HOWE, JT AF CORNELISON, CJ HOWE, JT TI ANALYTIC SOLUTION OF THE TRANSIENT-BEHAVIOR OF RADIATION-BACKSCATTERING HEAT SHIELDS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB An analytic solution of the material response to combined radiative and convective heating is presented. The solution includes the equations of radiative transfer (within the material), coupled to a transient energy equation that contains both radiative and convective terms. The analysis allows for unlimited spectral detail, but assumes that within the range of applicability, the various material properties do not vary significantly with temperature. To facilitate development of the analytic solution, it is also assumed that scattering within the material dominates absorption, and that the exposed surface of the material does not ablate. The exposed surface boundary condition includes convective heating and spectral radiation, some of which is absorbed by the surface and some of which penetrates the surface. C1 NASA, AMES RES CTR, DIV THERMOSCI, MOFFETT FIELD, CA 94035 USA. NR 14 TC 7 Z9 7 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1992 VL 6 IS 4 BP 612 EP 617 DI 10.2514/3.11541 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JW316 UT WOS:A1992JW31600005 ER PT J AU HARTUNG, LC AF HARTUNG, LC TI DEVELOPMENT OF A NONEQUILIBRIUM RADIATIVE HEATING PREDICTION METHOD FOR COUPLED FLOWFIELD SOLUTIONS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A method for predicting radiative heating and coupling effects in nonequilibrium flowfields has been developed. The method resolves atomic lines with a minimum number of spectral points and treats molecular radiation using the smeared band approximation. To further minimize computational time, the calculation is performed on an optimized spectrum that is computed for each flow condition to enhance spectral resolution. Additional time savings are obtained by performing the radiation calculation on a subgrid optimally selected for accuracy. Representative results from the new method are compared to previous work to demonstrate that speedup does not cause a loss of accuracy and is sufficient to make coupled solutions practical. The method is found to be a useful tool for studies of nonequilibrium flows. C1 NASA, LANGLEY RES CTR, DIV SPACE SYST, AGROTHERMODYNAM BRANCH, HAMPTON, VA 23665 USA. NR 17 TC 20 Z9 21 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 OCT-DEC PY 1992 VL 6 IS 4 BP 618 EP 625 DI 10.2514/3.11542 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JW316 UT WOS:A1992JW31600006 ER PT J AU OLYNICK, DP HASSAN, HA AF OLYNICK, DP HASSAN, HA TI MONTE-CARLO SIMULATION OF NONEQUILIBRIUM SHOCK FRONTS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A direct simulation of a shock tube experiment carried out by AVCO, (pressure of 1 Torr and velocity of 6.4 km/s) repeated by Sharma and Gillespie, and used by Park to develop his two-temperature model, is presented. Results show that the electronic ground state of N2 is not in rotational or vibrational equilibrium with that of N2+. Moreover, a two-temperature model is inadequate to describe nonequilibrium flows behind shocks. The role of impurities is examined. It is shown that the effects of a small fraction of H2O are insignificant. Good agreement with the measurements of Sharma and Gillespie is indicated. C1 N CAROLINA STATE UNIV, RALEIGH, NC 27695 USA. NASA, LANGLEY RES CTR, DIV SPACE SYST, AEROTHERMODYNAM BRANCH, HAMPTON, VA 23665 USA. NR 15 TC 2 Z9 2 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 OCT-DEC PY 1992 VL 6 IS 4 BP 626 EP 630 DI 10.2514/3.11543 PG 5 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JW316 UT WOS:A1992JW31600007 ER PT J AU CARLSON, AB HASSAN, HA AF CARLSON, AB HASSAN, HA TI RADIATION MODELING WITH DIRECT SIMULATION MONTE-CARLO SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Improvements in the modeling of radiation in low-density shock waves with direct simulation Monte Carlo (DSMC) are the subject of this study. A new scheme to determine the relaxation collision numbers for excitation of electronic states is proposed. This scheme attempts to move the DSMC programs toward a more detailed modeling of the physics and more reliance on available rate data. The new method is compared with the current modeling technique, and both techniques are compared with available experimental data. The differences in the results are evaluated. The test case is based on experimental measurements from the AVCO-Everett research laboratory electric arc-driven shock tube, of a normal shock wave in air, at 10 km/s and 0.1 Torr. The new method agrees with the available data as well as with the results from the earlier scheme, and is more easily extrapolated to different flow conditions. C1 NASA, LANGLEY RES CTR, DIV SPACE SYST, AEROTHERMODYNAM BRANCH, HAMPTON, VA 23665 USA. N CAROLINA STATE UNIV, DEPT MECH & AEROSP ENGN, RALEIGH, NC 27695 USA. NR 12 TC 13 Z9 13 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1992 VL 6 IS 4 BP 631 EP 636 DI 10.2514/3.11544 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JW316 UT WOS:A1992JW31600008 ER PT J AU DAGUM, L AF DAGUM, L TI 3-DIMENSIONAL DIRECT PARTICLE SIMULATION ON THE CONNECTION MACHINE SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB This paper presents the algorithms necessary for an efficient data parallel implementation of a three-dimensional particle simulation. A general master/slave algorithm and a fast sorting algorithm are described, and the use of these algorithms in a particle simulation is outlined. A particle simulation using these algorithms has been implemented on a 32768 processor connection machine that is capable of simulating over 30 million particles at an average rate of 2.4 mus/particle/step. Results are presented from the simulation of flow over an aeroassisted flight experiment (AFE) geometry at 100 km alt. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 17 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 OCT-DEC PY 1992 VL 6 IS 4 BP 637 EP 642 DI 10.2514/3.11545 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JW316 UT WOS:A1992JW31600009 ER PT J AU KAMOTANI, Y PLATT, J AF KAMOTANI, Y PLATT, J TI EFFECT OF FREE-SURFACE SHAPE ON COMBINED THERMOCAPILLARY AND NATURAL-CONVECTION SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID FLOW; BUOYANT; CAVITY AB Combined thermocapillary and natural convection in an open square cavity with differentially-heated side walls is studied numerically as well as experimentally. The test fluid is silicone oil with Prandtl number of 105. The shape of fluid-free surface is made either flat or curved to study its effect on the flow. A finite difference scheme to deal with a curved free surface is developed. The experimental results shown agree with the numerical results. With the curved-free surface, the flow and local heat transfer rate are reduced in the corner regions, and a sharp peak in heat transfer rate at the top edge of the cold wall disappears. C1 CASE WESTERN RESERVE UNIV, DEPT MECH & AEROSP ENGN, CLEVELAND, OH 44106 USA. NASA, LEWIS RES CTR, DIV SPACE EXPT, MICROGRAV FLUID BRANCH, CLEVELAND, OH 44135 USA. NR 16 TC 17 Z9 17 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 OCT-DEC PY 1992 VL 6 IS 4 BP 721 EP 726 DI 10.2514/3.11557 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA JW316 UT WOS:A1992JW31600021 ER PT J AU RAO, DK BROWN, GV LEWIS, P HURLEY, J AF RAO, DK BROWN, GV LEWIS, P HURLEY, J TI STIFFNESS OF MAGNETIC BEARINGS SUBJECTED TO COMBINED STATIC AND DYNAMIC LOADS SO JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT TRIBOLOGY CONF CY OCT 13-16, 1991 CL ST LOUIS, MO SP AMER SOC MECH ENGINEERS, SOC TRIBOLOGISTS & LUBRICAT ENGINEERS AB This paper investigates the stiffness of a magnetic bearing that is subjected to the combined action of static and dynamic loads. Since their sum cannot exceed the saturation load, a large static load will imply that the bearing can carry only a small dynamic load. This smaller dynamic load together with the practical vibration amplitude define a practical upper bound to the dynamic stiffness. This paper also presents approximate design formulas and curves for this stiffness capacity as a function of the ratio of dynamic and static loads. In addition, it indicates that vibrations larger than a certain gap fraction can destabilize the magnetic bearing. This gap fraction, called the critical gap fraction, depends on the dynamic and static load ratio. For example, if the dynamic load is half of the static load, the use of more than 25 percent of gap can destabilize the bearing. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP RAO, DK (reprint author), MECH TECHNOL INC,LATHAM,NY 12110, USA. NR 19 TC 4 Z9 6 U1 1 U2 2 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 OCT PY 1992 VL 114 IS 4 BP 785 EP 789 DI 10.1115/1.2920949 PG 5 WC Engineering, Mechanical SC Engineering GA JV888 UT WOS:A1992JV88800020 ER PT J AU CAMCI, C KIM, K HIPPENSTEELE, SA AF CAMCI, C KIM, K HIPPENSTEELE, SA TI A NEW HUE CAPTURING TECHNIQUE FOR THE QUANTITATIVE INTERPRETATION OF LIQUID-CRYSTAL IMAGES USED IN CONVECTIVE HEAT-TRANSFER STUDIES SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 03-06, 1991 CL ORLANDO, FL AB This study focuses on a new image processing based color capturing technique for the quantitative interpretation of liquid crystal images used in convective heat transfer studies. The present method is highly applicable to the surfaces exposed to convective heating in gas turbine engines. The study shows that, in single-crystal mode, many of the colors appearing on the heat transfer surface correlate strongly with the local temperature. A very accurate quantitative approach using an experimentally determined linear hue versus temperature relation is possible. The new hue-capturing process is discussed in detail, in terms of the strength of the light source illuminating the heat transfer surface, effect of the orientation of the illuminating source with respect to the surface, crystal layer uniformity, and the repeatability of the process. The method uses a 24-bit color image processing system operating in hue-saturation-intensity domain, which is an alternative to conventional systems using red-green-blue color definition. The present method is more advantageous than the multiple filter method because of its ability to generate many isotherms simultaneously from a single-crystal image at a high resolution, in a very time-efficient manner. The current approach is valuable in terms of its direct application to both steady-state and transient heat transfer techniques currently used for the hot section heat transfer research in air-breathing propulsion systems. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. RP CAMCI, C (reprint author), PENN STATE UNIV,DEPT AEROSP ENGN,UNIV PK,PA 16802, USA. NR 25 TC 100 Z9 101 U1 1 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 OCT PY 1992 VL 114 IS 4 BP 765 EP 775 DI 10.1115/1.2928030 PG 11 WC Engineering, Mechanical SC Engineering GA JV656 UT WOS:A1992JV65600010 ER PT J AU WAGNER, JH JOHNSON, BV GRAZIANI, RA YEH, FC AF WAGNER, JH JOHNSON, BV GRAZIANI, RA YEH, FC TI HEAT-TRANSFER IN ROTATING SERPENTINE PASSAGES WITH TRIPS NORMAL TO THE FLOW SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 03-06, 1991 CL ORLANDO, FL ID CHANNEL FLOW AB Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large-scale, multipass, heat transfer model with both radially inward and outward flow. Trip strips on the leading and trailing surfaces of the radial coolant passages were used to produce the rough walls. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature ratio, Rossby number, Reynolds number, and radius-to-passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges that are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from stationary and rotating similar models with trip strips. The heat transfer coefficients on surfaces, where the heat transfer increased with rotation and buoyancy, varied by as much as a factor of four. Maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels obtained with the smooth wall model. The heat transfer coefficients on surfaces where the heat transfer decreased with rotation, varied by as much as a factor of three due to rotation and buoyancy. It was concluded that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips and that the effects of rotation were markedly different depending upon the flow direction. C1 PRATT & WHITNEY AIRCRAFT,E HARTFORD,CT 06108. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP WAGNER, JH (reprint author), UNITED TECHNOL RES CTR,E HARTFORD,CT 06108, USA. NR 25 TC 74 Z9 75 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 OCT PY 1992 VL 114 IS 4 BP 847 EP 857 DI 10.1115/1.2928038 PG 11 WC Engineering, Mechanical SC Engineering GA JV656 UT WOS:A1992JV65600018 ER PT J AU RIZZI, SA DOYLE, JF AF RIZZI, SA DOYLE, JF TI A SPECTRAL ELEMENT APPROACH TO WAVE MOTION IN LAYERED SOLIDS SO JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME LA English DT Article AB A matrix methodology similar to that of the finite element method is developed for the analysis of stress waves in layered solids. Because the mass distribution is modeled exactly, the approach gives the exact frequency response of each layer. The fast Fourier transform and Fourier series are used for inversion to the time/space domain. The impact of a structured medium with multiple layers is used to demonstrate the method. Comparison with existing propagator and direct global matrix methods show the present approach to be computationally more efficient. RP RIZZI, SA (reprint author), NASA,LANGLEY RES CTR,STRUCT ACOUST BRANCH,HAMPTON,VA 23665, USA. NR 0 TC 62 Z9 66 U1 0 U2 6 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 1048-9002 J9 J VIB ACOUST JI J. Vib. Acoust.-Trans. ASME PD OCT PY 1992 VL 114 IS 4 BP 569 EP 577 DI 10.1115/1.2930300 PG 9 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA JV889 UT WOS:A1992JV88900020 ER PT J AU LEE, RU AF LEE, RU TI STATISTICAL-ANALYSIS OF CORROSION FAILURES OF LEAD-SHEATHED CABLES SO MATERIALS PERFORMANCE LA English DT Article AB Lead-sheathed cables serve as the primary carriers of communication signals at the Kennedy Space Center. Although the cable sheaths are connected to distributed rectifiers for cathodic protection, corrosion failures continue to occur. Recently, the effectiveness of the cathodic protection system was debated. The Type III extreme value distribution, or Weibull distribution, was used to analyze the corrosion failure data. Results of that analysis are discussed. RP LEE, RU (reprint author), NASA,MAT SCI LAB,DM-MSL-22,KENNEDY SPACE CTR,FL 32899, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU NATL ASSN CORROSION ENG PI HOUSTON PA 1440 SOUTH CREEK DRIVE, HOUSTON, TX 77084-4906 SN 0094-1492 J9 MATER PERFORMANCE JI Mater. Perform. PD OCT PY 1992 VL 31 IS 10 BP 20 EP 23 PG 4 WC Materials Science, Characterization & Testing SC Materials Science GA JV828 UT WOS:A1992JV82800002 ER PT J AU MOORE, TJ TELESMAN, J MOORE, AS JOHNSON, DF KUIVIEN, DE AF MOORE, TJ TELESMAN, J MOORE, AS JOHNSON, DF KUIVIEN, DE TI CRACKING OF 4-FT DIAMETER TYPE-316 AIR VALVE SO MATERIALS PERFORMANCE LA English DT Editorial Material RP MOORE, TJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU NATL ASSN CORROSION ENG PI HOUSTON PA 1440 SOUTH CREEK DRIVE, HOUSTON, TX 77084-4906 SN 0094-1492 J9 MATER PERFORMANCE JI Mater. Perform. PD OCT PY 1992 VL 31 IS 10 BP 63 EP 64 PG 2 WC Materials Science, Characterization & Testing SC Materials Science GA JV828 UT WOS:A1992JV82800012 ER PT J AU GALANT, D AF GALANT, D TI ALGEBRAIC METHODS FOR MODIFIED ORTHOGONAL POLYNOMIALS SO MATHEMATICS OF COMPUTATION LA English DT Article AB Some algebraic methods are given to implement Uvarov's extended Christoffel theorem. The stability of the algorithms is discussed. RP GALANT, D (reprint author), NASA,AMES RES CTR,INTELLIGENT SYST TECHNOL BRANCH,MOFFETT FIELD,CA 94035, USA. NR 8 TC 12 Z9 12 U1 0 U2 0 PU AMER MATHEMATICAL SOC PI PROVIDENCE PA 201 CHARLES ST, PROVIDENCE, RI 02940-2213 SN 0025-5718 J9 MATH COMPUT JI Math. Comput. PD OCT PY 1992 VL 59 IS 200 BP 541 EP 546 DI 10.2307/2153072 PG 6 WC Mathematics, Applied SC Mathematics GA JV301 UT WOS:A1992JV30100014 ER PT J AU KLEINBERG, LL AF KLEINBERG, LL TI OPAMP CIRCUITS VOID INDUCTORS IN RF FILTERS SO MICROWAVES & RF LA English DT Article RP KLEINBERG, LL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PENTON PUBL INC PI CLEVELAND PA 1100 SUPERIOR AVE, CLEVELAND, OH 44114 SN 0745-2993 J9 MICROWAVES RF JI Microw. RF PD OCT PY 1992 VL 31 IS 10 BP 96 EP & PG 0 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JV483 UT WOS:A1992JV48300012 ER PT J AU NAYLOR, T CHARLES, PA MUKAI, K EVANS, A AF NAYLOR, T CHARLES, PA MUKAI, K EVANS, A TI AN OBSERVATIONAL CASE AGAINST NOVA HIBERNATION SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE STARS INDIVIDUAL CK VUL; STARS INDIVIDUAL SS CYG; STARS INDIVIDUAL WY SGE; NOVAE CATACLYSMIC VARIABLES ID CATACLYSMIC BINARIES; CLASSICAL NOVAE; SPACE DENSITY; EVOLUTION; OLDEST; DWARF AB We use WHT spectroscopy and imaging to show that nova Vul 1670 (= CK Vul) has been incorrectly identified, and thus its luminosity cannot be used as evidence that novae fade into a 'hibernation' phase within 300 yr of their outbursts. INT spectroscopy is used to correct the magnitude of nova Sge 1783 (= WY Sge) for inclination, this result also implying that novae do not fade significantly. We therefore suggest that, whilst novae decline in the first 60 yr after outburst, thereafter their luminosity remains constant, and they never undergo a 'hibernation' phase. We show that this idea is consistent with the space density of novae and nova-like variables, the outburst interval of SS Cyg and the current luminosities of old novae. C1 NASA,GODDARD SPACE FLIGHT CTR,OFF GUEST INVEST PROGRAMS,GREENBELT,MD 20771. DEPT ASTROPHYS,OXFORD OX1 3RH,ENGLAND. RP NAYLOR, T (reprint author), UNIV KEELE,DEPT PHYS,KEELE ST5 5BG,STAFFS,ENGLAND. RI Naylor, Tim /A-9465-2015 NR 31 TC 29 Z9 29 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 OCT 1 PY 1992 VL 258 IS 3 BP 449 EP 456 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JR038 UT WOS:A1992JR03800001 ER PT J AU CHAHINE, MT AF CHAHINE, MT TI THE HYDROLOGICAL CYCLE AND ITS INFLUENCE ON CLIMATE SO NATURE LA English DT Review ID AMAZON DEFORESTATION; SURFACE-TEMPERATURE; NORTH-ATLANTIC; GLOBAL-MODELS; FEEDBACK; PRECIPITATION; PARAMETERS; CO2 AB The uncertainties in assessing the effects of global-scale perturbations to the climate system are due primarily to an inadequate understanding of the hydrological cycle-the cycling of water in the oceans, atmosphere and biosphere. Overcoming this problem necessitates new ways of regarding a field traditionally divided amongst several disciplines, as well as new instrumentation and methods of data collection. RP CHAHINE, MT (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 62 TC 255 Z9 290 U1 10 U2 57 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 1 PY 1992 VL 359 IS 6394 BP 373 EP 380 DI 10.1038/359373a0 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JQ624 UT WOS:A1992JQ62400044 ER PT J AU HANDSCHUH, RF KEITH, TG AF HANDSCHUH, RF KEITH, TG TI APPLICATIONS OF AN EXPONENTIAL FINITE-DIFFERENCE TECHNIQUE SO NUMERICAL HEAT TRANSFER PART A-APPLICATIONS LA English DT Article ID HEAT-CONDUCTION; EQUATION AB In this paper an expontial finite-difference scheme, first presented by Bhattacharya for one-dimensional, unsteady heat conduction problems in a plane wall, is used to solve various partial differential equations. Solutions of the unsteady diffusion equation in three dimensions and of the viscous form of Burgers' equation are used to illustrate the method. Predicted results are compared with exact solutions or with results obtained by other numerical methods. C1 UNIV TOLEDO,DEPT MECH ENGN,TOLEDO,OH 43606. RP HANDSCHUH, RF (reprint author), USA,AVIAT RES & TECHNOL ACT,AVSCOM,LEWIS RES CTR,PROPULS DIRECTORATE,CLEVELAND,OH 44135, USA. NR 8 TC 7 Z9 7 U1 0 U2 0 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 1040-7782 J9 NUMER HEAT TR A-APPL JI Numer. Heat Tranf. A-Appl. PD OCT-NOV PY 1992 VL 22 IS 3 BP 363 EP 378 DI 10.1080/10407789208944773 PG 16 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA JU962 UT WOS:A1992JU96200006 ER PT J AU EGALON, CO ROGOWSKI, RS AF EGALON, CO ROGOWSKI, RS TI SOURCE POLARIZATION EFFECTS IN AN OPTICAL FIBER FLUOROSENSOR SO OPTICAL ENGINEERING LA English DT Article DE CIRCULAR OPTICAL FIBERS; OPTICAL FLUOROSENSORS; ELECTROMAGNETIC THEORY; ACTIVE CLADDING OPTICAL FIBERS; OPTICAL FIBER SENSORS; STEP-INDEX PROFILE FIBERS; POLARIZED SOURCES ID FLUORESCENCE AB The exact field solution of a step-index profile fiber was used to determine the injection efficiency of a thin-film distribution of polarized sources located in the cladding of an optical fiber. Previous results for random source orientation were confirmed. The behavior of the power efficiency, P(eff), of a polarized distribution of sources was found to be similar to the behavior of a fiber with sources with random orientation. However, for sources polarized in either the x or y direction, P(eff) was found to be more efficient. RP EGALON, CO (reprint author), NASA,LANGLEY RES CTR,NONDESTRUCT EVALUAT SCI BRANCH,MAIL STOP 231,HAMPTON,VA 23665, USA. NR 12 TC 2 Z9 2 U1 0 U2 1 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 OCT PY 1992 VL 31 IS 10 BP 2213 EP 2217 DI 10.1117/12.59979 PG 5 WC Optics SC Optics GA JR990 UT WOS:A1992JR99000022 ER PT J AU CHENG, TD ANGELICI, GL SLYE, RE MA, M AF CHENG, TD ANGELICI, GL SLYE, RE MA, M TI INTERACTIVE BOUNDARY DELINEATION OF AGRICULTURAL LANDS USING GRAPHICS WORKSTATIONS SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article AB The National Agricultural Statistics Service of the United States Department of Agriculture presently uses labor-intensive aerial photographic interpretation to divide large geographical areas into manageable-sized units for estimating domestic crop and livestock production. Prototype software to automate the boundary delineation procedure, called the Computer-Assisted Stratification and Sampling (CASS) procedure, was developed by the National Aeronautics and Space Administration. The procedure uses image processing software on a Hewlett-Packard graphics workstation for the development of the operational approach. Over a background display of a Landsat Thematic Mapper image and United States Geological Survey Digital Line Graph data, the operator uses a cursor to delineate agricultural areas, called sampling units, which are assigned to strata of land-use and land-cover types. The sampling units are used for subsequent sampling procedures. Three counties in Missouri were chosen for evaluation of the CASS procedures. Analysis indicates that CASS is up to six times faster than the manual techniques in creating sampling units. C1 NASA,AMES RES CTR,STERLING SOFTWARE INC,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,ECOSYST SCI & TECHNOL BRANCH,MOFFETT FIELD,CA 94035. RP CHENG, TD (reprint author), NASA,AMES RES CTR,TGS TECHNOL INC,MS 242-4,MOFFETT FIELD,CA 94035, USA. NR 4 TC 3 Z9 4 U1 0 U2 2 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 OCT PY 1992 VL 58 IS 10 BP 1439 EP 1443 PG 5 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA JR083 UT WOS:A1992JR08300004 ER PT J AU BOZZOLO, G FERRANTE, J AF BOZZOLO, G FERRANTE, J TI DETERMINATION OF PARAMETERS OF A METHOD FOR PREDICTING ALLOY PROPERTIES SO PHYSICAL REVIEW B LA English DT Note ID EQUIVALENT-CRYSTAL THEORY; ELECTRONIC THEORY; PHASE-STABILITY; METAL; AG; AU AB Recently, a semiempirical method for alloys based on equivalent-crystal theory was introduced [Phys. Rev. B 45, 943 (1992)]. The method successfully predicts the concentration dependence of the heat of formation and lattice parameter of binary alloys. In this report, a study of the parameters of the method is presented, along with new results for gamma-Fe-Pd and gamma-Fe-Ni alloys. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOZZOLO, G (reprint author), ANALEX CORP,3001 AEROSP PKWY,BROOK PK,OH 44142, USA. NR 15 TC 15 Z9 16 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD OCT 1 PY 1992 VL 46 IS 13 BP 8600 EP 8602 DI 10.1103/PhysRevB.46.8600 PG 3 WC Physics, Condensed Matter SC Physics GA JT040 UT WOS:A1992JT04000080 ER PT J AU CUCINOTTA, FA TOWNSEND, LW WILSON, JW AF CUCINOTTA, FA TOWNSEND, LW WILSON, JW TI MULTIPLE-SCATTERING EFFECTS IN QUASI-ELASTIC ALPHA-HE-4 SCATTERING SO PHYSICAL REVIEW C LA English DT Article ID INELASTIC-SCATTERING; PARTICLES; ENERGIES; NUCLEI; PHASE AB A multiple-scattering series for describing the quasielastic peak in nucleus-nucleus collisions is derived using the high-energy optical model. The effects of multiple knockout of target nucleons and internal excitation of the projectile are studied and found to be important for large energy loss and momentum transfers in inclusive alpha-He-4 scattering at 7 GeV/c. An approximate evaluation of higher-order inelastic collision terms is considered for forward-peaked wave functions and is demonstrated to be accurate. RP CUCINOTTA, FA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 19 TC 10 Z9 10 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD OCT PY 1992 VL 46 IS 4 BP 1451 EP 1456 DI 10.1103/PhysRevC.46.1451 PG 6 WC Physics, Nuclear SC Physics GA JU931 UT WOS:A1992JU93100033 PM 9968254 ER PT J AU NARDI, E ROULET, E TOMMASINI, D AF NARDI, E ROULET, E TOMMASINI, D TI SIMULTANEOUS ANALYSIS OF Z' AND NEW FERMION EFFECTS - GLOBAL CONSTRAINTS IN E6 AND SO(10) MODELS SO PHYSICAL REVIEW D LA English DT Article ID PRECISION ELECTROWEAK EXPERIMENTS; QED RADIATIVE-CORRECTIONS; HEAVY FLAVOR PRODUCTION; PARITY NON-CONSERVATION; NEUTRAL GAUGE BOSONS; STANDARD MODEL; BACKWARD ASYMMETRY; E+E ANNIHILATION; Z-DECAYS; TAU->PI(K)NU DECAYS AB In grand unified theories based on extended (rank >4) gauge groups, the new gauge interactions require new fermions to ensure anomaly cancellation. We analyze the two kinds of new physics effects that are naturally present in these models: (i) the effects of the new neutral gauge bosons; (ii) the effects of a mixing of the known fermions with the new ones. Concentrating in particular on E6 and SO(10) models, we perform a global analysis of the electroweak data to constrain simultaneously these two new physics effects, and we pay particular attention to their reciprocal interplay. Our set of experimental results includes the data at the CERN e+e- collider LEP on the Z decay widths and fermion asymmetries, low-energy neutral-current experiments (atomic parity violation, nu scattering), the W-boson mass M(W), as well as charged-current measurements such as the various tests of the universality of the W-lepton couplings and the constraints on unitarity of the Cabibbo-Kobayashi-Maskawa matrix. We derive stringent bounds on the Z0-Z1 mixing (Absolute value of phi less than or similar to 0.02), on the fermion mixing parameters (sin2xi(i) less than or similar to 0.01 in most cases), and on the mass of the new gauge boson (M(Z') > 170-350 GeV, depending on the model). In many observables the different sources of new physics induce comparable effects that can compensate each other. We confront the results derived by considering only one effect at a time with the results of a joint analysis, and we point out which of the existing bounds are relaxed and which ones remain unaffected. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV VALENCIA,INST FIS CORPUSCULAR,E-46100 BURJASSOT,SPAIN. RP NARDI, E (reprint author), UNIV MICHIGAN,RANDALL LAB PHYS,ANN ARBOR,MI 48109, USA. RI Tommasini, Daniele/L-4718-2014; OI Tommasini, Daniele/0000-0002-7997-3088; Nardi, Enrico/0000-0001-7165-3808 NR 109 TC 50 Z9 50 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 1 PY 1992 VL 46 IS 7 BP 3040 EP 3061 DI 10.1103/PhysRevD.46.3040 PG 22 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA JQ377 UT WOS:A1992JQ37700034 ER PT J AU BAER, E HILTNER, A MORGAN, RJ AF BAER, E HILTNER, A MORGAN, RJ TI BIOLOGICAL AND SYNTHETIC HIERARCHICAL COMPOSITES SO PHYSICS TODAY LA English DT Article ID BIOMINERALIZATION C1 NASA,CTR COMMERCIAL DEV SPACE MAT SPACE STRUCT,WASHINGTON,DC 20546. MICHIGAN MACROMOLEC INST,COMPOSITES PROGRAM,MIDLAND,MI 48640. RP BAER, E (reprint author), CASE WESTERN RESERVE UNIV,CTR APPL POLYMER RES,CLEVELAND,OH 44106, USA. NR 23 TC 35 Z9 35 U1 1 U2 9 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 OCT PY 1992 VL 45 IS 10 BP 60 EP 67 DI 10.1063/1.881344 PG 8 WC Physics, Multidisciplinary SC Physics GA JU119 UT WOS:A1992JU11900010 ER PT J AU HAMILL, P TOON, OB AF HAMILL, P TOON, OB TI CAN BAND-AIDS CLOSE THE OZONE HOLE - REPLY SO PHYSICS TODAY LA English DT Letter C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HAMILL, P (reprint author), SAN JOSE STATE UNIV,SAN JOSE,CA 95192, USA. NR 1 TC 0 Z9 0 U1 0 U2 1 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 OCT PY 1992 VL 45 IS 10 BP 141 EP 141 PG 1 WC Physics, Multidisciplinary SC Physics GA JU119 UT WOS:A1992JU11900026 ER PT J AU VILLANTE, U LEPIDI, S VELLANTE, M LAZARUS, AJ LEPPING, RP AF VILLANTE, U LEPIDI, S VELLANTE, M LAZARUS, AJ LEPPING, RP TI PC3 ACTIVITY AT LOW GEOMAGNETIC LATITUDES - A COMPARISON WITH SOLAR-WIND OBSERVATIONS SO PLANETARY AND SPACE SCIENCE LA English DT Article ID HYDROMAGNETIC ENERGY-SPECTRA; MAGNETIC-FIELD DIRECTION; PULSATIONS; MAGNETOSPHERE; WAVES; DEPENDENCE; VELOCITY; ORIENTATION; STATIONS; SIGNALS AB On an hourly time-scale the different roles of the solar wind and interplanetary magnetic field (IMF) parameters on ground micropulsation activity can be better investigated than at longer time-scales. A long-term comparison between ground measurements made at L'Aquila (L is-approximately-equal-to 1.6) and IMP 8 observations confirms the solar wind speed as the key parameter for the onset of pulsations even at low latitudes, although additional control of the energy transfer from the interplanetary medium to the Earth's magnetosphere is clearly exerted by the cone angle. Above is-approximately-equal-to 20 mHz the frequency of pulsations is confirmed to be closely related to the IMF magnitude while, in agreement with model predictions, the IMF magnitude is related to the amplitude of the local fundamental resonant mode. We provide an interesting example in which high resolution measurements simultaneously obtained in the foreshock region and on the ground show that external transversal fluctuations do not penetrate deep into the low latitude magnetosphere. C1 MIT,DEPT PHYS,CAMBRIDGE,MA 02139. MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP VILLANTE, U (reprint author), UNIV LAQUILA,DIPARTIMENTO FIS,I-67100 LAQUILA,ITALY. OI Villante, Umberto/0000-0002-3630-7958 NR 30 TC 6 Z9 6 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD OCT PY 1992 VL 40 IS 10 BP 1399 EP 1408 DI 10.1016/0032-0633(92)90095-6 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JY619 UT WOS:A1992JY61900009 ER PT J AU TAKEDA, H SAITO, J HIROI, T AF TAKEDA, H SAITO, J HIROI, T TI A NEW TYPE OF ANTARCTIC ACHONDRITES AND THEIR RELATIONSHIP TO S-ASTEROIDS AND CHONDRITES SO PROCEEDINGS OF THE JAPAN ACADEMY SERIES B-PHYSICAL AND BIOLOGICAL SCIENCES LA English DT Article DE PRIMITIVE ACHONDRITE; S-ASTEROID; PYROXENE MINERALOGY; CHONDRITE ID UREILITES AB Five meteorites recovered from Antarctica are unique achondrites with coarse-grained orthopyroxene and olivine crystals and variable amounts of Ni-Fe metal and FeS with additional augite or plagioclase. These mineral species can be found in chondrites, which are the most common types among the observed falls. Both Y74357 and MAC88177 contain considerable augite, but Y74357 is richer in olivine. Y791491 contains minor plagioclase. Discovery of such meteorites with coarse-grained texture and similar major mineral chemistry with extensively modified chondritic bulk chemistries suggest that they are related meteorites with variable amounts of augite and plagioclase and variable degree of reduction. The variability of mineral abundance can be explained by different degree of removal or segregation of partial melts, by a radiogenic internal heating and collisional one. Reflectance spectra of some members of this group combined with those of iron meteorites resemble those of S asteroids common in the main belt. The trend of their variation in mineral assemblage is in line with those of the S asteroids. This model also explains the absence of chondritic asteroids in the main belt, because S asteroids may be modified products of larger chondritic bodies. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP TAKEDA, H (reprint author), UNIV TOKYO,FAC SCI,INST MINERAL,TOKYO 113,JAPAN. NR 19 TC 4 Z9 4 U1 0 U2 0 PU JAPAN ACAD PI TOKYO PA UENO PARK, TOKYO 110, JAPAN SN 0386-2208 J9 P JPN ACAD B-PHYS JI Proc. Jpn. Acad. Ser. B-Phys. Biol. Sci. PD OCT PY 1992 VL 68 IS 8 BP 115 EP 120 DI 10.2183/pjab.68.115 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JY725 UT WOS:A1992JY72500001 ER PT J AU HORCH, E MORGAN, JS GIARETTA, G KASLE, DB AF HORCH, E MORGAN, JS GIARETTA, G KASLE, DB TI A NEW-SPECKLE INTERFEROMETRY SYSTEM FOR THE MAMA DETECTOR SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID STARS AB We have developed a new system for making speckle observations with the multianode microchannel array (MAMA) detector. This system is a true photon-counting imaging device which records the arrival time of every detected photon and allows for reconstruction of image features near the diffraction limit of the telescope. We present a description of the system and summary of observational results obtained at the Lick Observatory 1-m reflector in 1991 September. The diffraction limit of the 1-m telescope at 5029 angstrom is about 0.125 arcsec and we have successfully resolved the catalogued interferometric binary HD 202582 with a separation of 0. 157 +/- 0.031 arcsec. A pair of stars in the open cluster chi Persei separated by 2.65 +/- 0.22 arcsec with approximate V magnitudes 8.6 and 11.5 has also been successfully analyzed with the speckle technique. C1 UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98125. STANFORD UNIV,DEPT ELECT ENGN,STANFORD,CA 94305. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. STANFORD UNIV,ERL,CSSA,DEPT ELECT ENGN,STANFORD,CA 94305. RP HORCH, E (reprint author), STANFORD UNIV,DEPT APPL PHYS,STANFORD,CA 94305, USA. NR 14 TC 8 Z9 8 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD OCT PY 1992 VL 104 IS 680 BP 939 EP 948 DI 10.1086/133078 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JV534 UT WOS:A1992JV53400009 ER PT J AU WOOD, KS FELDMAN, U BECKER, PA NEMIROFF, RJ KANIA, DR AF WOOD, KS FELDMAN, U BECKER, PA NEMIROFF, RJ KANIA, DR TI A FOURIER-TRANSFORM MICROSCOPE FOR X-RAY-IMAGING SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article; Proceedings Paper CT 9TH TOPICAL CONF ON HIGH TEMPERATURE PLASMA DIAGNOSTICS CY MAR 15-19, 1992 CL SANTA FE, NM SP AMER PHYS SOC, US DOE, OFF INERTIAL CONFINEMENT FUS, US DOE, OFF FUS ENERGY, DIV APPL PLASMA PHYS, SANDIA NATL LABS, INERTIAL CONFINEMENT FUS PROGRAM AB This is a progress report on development of a new x-ray imaging system, called a Fourier transform microscope, intended for use with x-ray emitting targets in laser fusion experiments. It is being built by Naval Research Laboratory and Lawrence Livermore National Laboratory. The system works at energies from 3 to 7 keV. We describe the development of the design, which utilizes fine etched grids to extract Fourier amplitudes for the source brightness distribution at selected spatial frequencies. The finest grids in the prototype system will have rib dimensions of 2 mum. The prototype system is expected to achieve position resolution of 4 mum in 3-7 keV. Simulations of the expected imaging performance are presented. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. RP WOOD, KS (reprint author), USN,RES LAB,WASHINGTON,DC 20375, USA. NR 8 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 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 1992 VL 63 IS 10 BP 5089 EP 5093 DI 10.1063/1.1143501 PN 2 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JV133 UT WOS:A1992JV13300164 ER PT J AU KENNEDY, JM BARNETT, TR FARLEY, GL AF KENNEDY, JM BARNETT, TR FARLEY, GL TI EXPERIMENTAL AND ANALYTICAL EVALUATION OF A BIAXIAL TEST FOR DETERMINING INPLANE SHEAR PROPERTIES OF COMPOSITES SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article AB The results of an experimental and analytical investigation of a biaxial tension-compression test for determining shear properties of composite materials are presented. A fixture was designed to introduce an equal and opposite pair of forces into a cruciform like specimen. The cruciform specimen was designed using finite element analysis. Carbon-epoxy composite ([90/0]2S and [+/- 45]2S) and aluminum specimens were tested in the fixture. The finite element analysis and strains measured during the tests showed that the stress state in the center of a cruciform specimen with large corner radii was pure shear. Stress gradients near the boundary of the test section were small, and the optimal specimen geometry was independent of laminate orientation. Shear strength was less than anticipated because failure initiated due to instability or due to a complex inplane and interlaminar stress state at the specimen boundaries. The shear stress-strain results from the cruciform test were compared with results from the Iosipescu test and the +/- 45-degrees tensile test. The shear moduli determined with the cruciform specimen compared favorably with the moduli obtained using the other two methods. The lamina shear strength measured using the cruciform specimen was higher than the strength measured using the other methods. The strength of a [+/- 45]2S laminate as determined using the cruciform specimen was lower due to instability related failure than that determined by the Iosipescu shear test. C1 SO RES CORP,BIRMINGHAM,AL. USA,AEROSTRUCT DIRECTORATE,NASA,LANGLEY RES CTR,HAMPTON,VA. RP KENNEDY, JM (reprint author), CLEMSON UNIV,DEPT MECH ENGN,CLEMSON,SC 29631, USA. NR 16 TC 6 Z9 6 U1 1 U2 1 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0036-0821 J9 SAMPE QUART PD OCT PY 1992 VL 24 IS 1 BP 28 EP 37 PG 10 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA JT050 UT WOS:A1992JT05000004 ER PT J AU BURKS, HD STCLAIR, TL AF BURKS, HD STCLAIR, TL TI MELT FLOW PROPERTIES OF LARC(TM)-TPI 1500 SERIES MIXTURES SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article AB This study examines the melt-flow properties of 50150 mixtures of high flow grade/medium flow grade LARC(TM)-TPI 1500 series pellets and a new form, (9416), of medium flow grade material which contains 6 percent of a low molecular weight imide additive. The flow properties are compared with previously reported flow properties of mixtures of earlier batches of high and medium flow grade TPI 1500 materials. Unlike the earlier batches of materials, the later materials were synthesized and mixed at Mitsui Toatsu Chemicals, Inc.,* Japan, and made into pellets before NASA received them for characterization. They exhibited a lower melt viscosity as well as improved melt stability. RP BURKS, HD (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 11 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 OCT PY 1992 VL 24 IS 1 BP 50 EP 53 PG 4 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA JT050 UT WOS:A1992JT05000007 ER PT J AU GRIFFITHS, DF STUART, AM YEE, HC AF GRIFFITHS, DF STUART, AM YEE, HC TI NUMERICAL WAVE-PROPAGATION IN AN ADVECTION EQUATION WITH A NONLINEAR SOURCE TERM SO SIAM JOURNAL ON NUMERICAL ANALYSIS LA English DT Article DE NUMERICAL WAVE PROPAGATION; HETEROCLINIC ORBITS AB The Cauchy and initial boundary value problems are studied for a linear advection equation with a nonlinear source term. The source term is chosen to have two equilibrium states, one unstable and the other stable as solutions of the underlying characteristic equation. The true solutions exhibit travelling waves which propagate from one equilibrium to another. The speed of propagation is dependent on the rate of decay of the initial data at infinity. A class of monotone explicit finite-difference schemes are proposed and analysed; the schemes are upwind in space for the advection term with some freedom of choice for the evaluation of the nonlinear source term. Convergence of the schemes is demonstrated and the existence of numerical waves, mimicking the travelling waves in the underlying equation, is proved. The convergence of the numerical wave-speeds to the true wave-speeds is also established. The behaviour of the scheme is studied when the monotonicity criteria are violated due to stiff source terms, and oscillations and divergence are shown to occur. The behaviour is contrasted with a split-step scheme where the solution remains monotone and bounded but where incorrect speeds of propagation are observed as the stiffness of the problem increases. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV BATH,SCH MATH SCI,BATH BA2 7AY,AVON,ENGLAND. RP GRIFFITHS, DF (reprint author), UNIV DUNDEE,DEPT MATH & COMP SCI,DUNDEE DD1 4HN,SCOTLAND. NR 8 TC 41 Z9 41 U1 0 U2 1 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 OCT PY 1992 VL 29 IS 5 BP 1244 EP 1260 DI 10.1137/0729074 PG 17 WC Mathematics, Applied SC Mathematics GA JQ327 UT WOS:A1992JQ32700002 ER PT J AU JAFFE, LD LEBRETON, JP AF JAFFE, LD LEBRETON, JP TI THE CRAF CASSINI SCIENCE INSTRUMENTS, SPACECRAFT, AND MISSIONS SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article; Proceedings Paper CT 41ST CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 06-12, 1990 CL DRESDEN, GERMANY SP INT ASTRONAUT FEDERAT AB CRAF and Cassini are the first two missions planned for Mariner Mark II spacecraft. The CRAF (Comet Rendezvous Asteroid Flyby) mission includes flyby of a main-belt asteroid, rendezvous with a short-period comet near aphelion, orbit about the nucleus until after perihelion, and placement of an instrumented penetrator/lander on the nucleus. Cassini includes flyby of a main-belt asteroid; placing the spacecraft into orbit about Saturn; observing Saturn and its satellites for about 59 orbits; and deploying a probe, called Huygens, into the atmosphere of Titan. Thirty-five of these orbits will include a flyby of Titan; close flybys of Iapetus, Enceladus, and Dione are also planned. Mission durations will be 8 10 years for CRAF and Cassini, respectively. Mariner Mark II spacecraft are intended for multiple missions in the outer solar system. Total spacecraft mass will be about 5400 kg; dry mas is about 1650 kg for CRAF and 1950 kg for Cassini (which includes probe mass of 220 kg). About 3700 kg of nitrogen tetroxide and monomethyl hydrazine will be the main propellants. Each spacecraft has a high-precision scan platform (HPSP) with 2 degrees of freedom, plus additional platforms and/or turntables for mounting of science instruments. The spacecraft will be 3-axis stabilized by hydrazine thrusters plus reaction wheels. Attitude control will be referenced to optical gyros, a sun sensor, and a target-and-star sensor that utilizes a charge-coupled device (CCD); the gyros and target sensor are mounted on the HPSP. Radioisotope thermoelectric generators (RTGs) and NiCd batteries will provide power. Communication will be at X-band through a fixed 3.7 m antenna. The command and data subsystem will incorporate digital tape recorders and solid-state buffer memory, and will use packet telemetry to communicate with other subsystems via standardized interfaces. The Huygens Titan probe is conceived as a spin-stabilized, blunt-nosed 220-kg descent module with a jettisonable decelerator. Li/SO2 batteries will provide electrical energy. Communication after probe-orbiter separation will be limited to S-band telemetry from probe to orbiter. Thirteen scientific instruments have been selected as the tentative science payload for CRAF. Remote-sensing instruments will be CCD cameras, a mapping spectrometer, and a thermal infrared radiometer. Dust and gas instruments include spectrometers to analyze mass, energy, and direction of incident dust, ice, gas, ions, and electrons; a gas chromatograph; X-ray fluorescence spectrometers; and a scanning electron microscope for observations of individual dust particles. Two instruments will measure magnetic fields and plasma processes. The nucleus penetrator/lander will contain a gamma-ray spectrometer, a differential scanning calorimeter, evolved gas analyzer, thermal probes, and impact accelerometers. A radio science experiment also will be supported. For the Cassini orbiter, imaging and mapping spectrometer instruments, a Titan radar mapper, and some radio science hardware tentatively will be provided. The radar mapper utilizes the orbiter's high gain antenna, with Ku- and S-band feeds, and will have five operating modes: synthetic aperture radar, multibeam imager, altimeter, sounder, and scatterometer. The orbiter radio science experiment will utilize the X-band communications link. Other orbiter and all probe instruments will be selected competitively and provided by separate investigator teams. A model orbiter payload includes spectrometers operating at wavelengths from ultraviolet to microwave; a high-speed photometer; a variety of instruments for analysis of gas, ions, dust, plasma, and electromagnetic fields; and a microwave thermal mapper. The Huygens probe S-band relay link could be used for Doppler measurements of Titan winds. A model Huygens payload would provide measurements of Titan atmospheric structure, winds, and composition (including aerosol), and surface state and composition as well as cloud and surface images, surface and subsurface radar characteristics, and measurements of Titan lightning. RP JAFFE, LD (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 2 Z9 2 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD OCT PY 1992 VL 12 IS 4 BP 369 EP 392 PG 24 WC Engineering, Aerospace SC Engineering GA JR110 UT WOS:A1992JR11000005 ER PT J AU SOBIESZCZANSKISOBIESKI, J AF SOBIESZCZANSKISOBIESKI, J TI A TECHNIQUE FOR LOCATING FUNCTION ROOTS AND FOR SATISFYING EQUALITY CONSTRAINTS IN OPTIMIZATION SO STRUCTURAL OPTIMIZATION LA English DT Note AB A new technique for locating simultaneous roots of a set of functions is described. The technique is based on the property of the Kreisselmeier-Steinhauser function which descends to a minimum at each root location. It is shown that the ensuing algorithm may be merged into any nonlinear programming method for solving optimization problems with equality constraints. RP SOBIESZCZANSKISOBIESKI, J (reprint author), NASA,LANGLEY RES CTR,INTERDISCIPLINARY RES OFF,MS246,HAMPTON,VA 23665, USA. NR 0 TC 7 Z9 10 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0934-4373 J9 STRUCT OPTIMIZATION JI Struct. Optim. PD OCT PY 1992 VL 4 IS 3-4 BP 241 EP 243 DI 10.1007/BF01742751 PG 3 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary; Mechanics SC Computer Science; Engineering; Mechanics GA KC455 UT WOS:A1992KC45500016 ER PT J AU TOFT, PB TAYLOR, PT ARKANIHAMED, J HAGGERTY, SE AF TOFT, PB TAYLOR, PT ARKANIHAMED, J HAGGERTY, SE TI INTERPRETATION OF SATELLITE MAGNETIC-ANOMALIES OVER THE WEST AFRICAN CRATON SO TECTONOPHYSICS LA English DT Article ID MAGSAT DATA; SUSCEPTIBILITY; MODEL; MAP; LITHOSPHERE; PERSPECTIVE; TECTONICS; EVOLUTION; FEATURES; REGION AB Satellite magnetic anomaly maps of west Africa display persistent anomalies that are spatially related to the geological structure of the West African Craton. The Reguibat and Man shields to the north and south of the Taoudeni Basin have positive magnetization contrasts whereas the basin, which was disrupted by rifting and volcanism in the Late Proterozoic and Mesozoic, has a negative magnetization contrast. A forward model of the craton is developed, based on the surface geology and including aspects of the evolution of deep-seated thermal, petrological, and magnetization contrasts. Anomalies calculated from the model correspond fairly weil to the most reliable observed anomalies. The anomaly associated with the basin is due partly to the anomalies arising from the shields and partly to intra-basin deep-seated demagnetization resulting from Mesozoic thermal and metasomatic demagnetization. Another similar demagnetized zone probably contributes to the Reguibat Shield anomaly. The Man Shield anomaly results primarily from the Archean segment of this shield. The largest magnetization contrast required, for a 70-km-thick shield slab, is +0.3 A m-1. C1 NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. UNIV MASSACHUSETTS,DEPT GEOL,AMHERST,MA 01003. RP TOFT, PB (reprint author), MCGILL UNIV,DEPT GEOL SCI,MONTREAL H3A 2A7,QUEBEC,CANADA. RI Taylor, Patrick/D-4707-2012 OI Taylor, Patrick/0000-0002-1212-9384 NR 74 TC 8 Z9 8 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD OCT 1 PY 1992 VL 212 IS 1-2 BP 21 EP 32 DI 10.1016/0040-1951(92)90137-U PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU482 UT WOS:A1992JU48200003 ER PT J AU GIRDLER, RW TAYLOR, PT FRAWLEY, JJ AF GIRDLER, RW TAYLOR, PT FRAWLEY, JJ TI A POSSIBLE IMPACT ORIGIN FOR THE BANGUI MAGNETIC ANOMALY (CENTRAL AFRICA) SO TECTONOPHYSICS LA English DT Article ID SHOCK REMANENT MAGNETIZATION; VREDEFORT STRUCTURE; ROCKS; DEMAGNETIZATION; FEATURES AB Bangui is one of the most impressive magnetic anomalies on Earth and by far the largest over Africa. At Magsat altitudes, it has an amplitude of 28 nT and covers an area of 700,000 km2. Evidence presented suggests that the anomaly might be related to a large impact structure early in the history of the Earth: north-south, west-east, and vertical derivatives of the 5-min topographic data base all reveal a double ring structure with outer ring diameter approximately 810 km and inner ring diameter approximately 490 km. The Precambrian geology shows several small ancient basins within a large basin with a basement high in the middle such as found in large impact structures. The basement complex is early Precambrian and hence the impact must be of this age. The magnetic anomaly is interpreted as being due to strong remanent magnetism in the ancient crater floor and surrounds. The anomaly can be satisfactorily modelled by a 4.5-km-thick disc, 800 km in diameter beneath the ancient basins. To model the amplitude and shape of the anomaly requires an intensity of 10 A m-1 with direction D = N 18-degrees-W, I = + 25-degrees, i.e., significantly different from the present dipole field. The magnetisation is likely to include strong shock remanence (SRM) acquired at the time of impact, thermal remanence (TRM), partial thermal remanence (PTRM), thermochemical remanence (TCRM) and chemical remanence (CRM) acquired soon after the impact. All depend on the size of the impact and all contribute to the high intensity required to explain the anomaly. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. HERRING BAY GEOPHYS,DUNKIRK,MD 20754. RP GIRDLER, RW (reprint author), UNIV NEWCASTLE UPON TYNE,DEPT PHYS,NEWCASTLE TYNE NE1 7RU,TYNE & WEAR,ENGLAND. RI Taylor, Patrick/D-4707-2012 OI Taylor, Patrick/0000-0002-1212-9384 NR 43 TC 24 Z9 24 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD OCT 1 PY 1992 VL 212 IS 1-2 BP 45 EP 58 DI 10.1016/0040-1951(92)90139-W PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU482 UT WOS:A1992JU48200005 ER PT J AU RAJARAM, M LANGEL, RA AF RAJARAM, M LANGEL, RA TI MAGNETIC ANOMALY MODELING AT THE INDO EURASIAN COLLISION ZONE SO TECTONOPHYSICS LA English DT Article ID MAGSAT DATA; TIBETAN PLATEAU; SOUTHERN TIBET; CRUST; EVOLUTION; FIELD; INVERSION; TECTONICS; BENEATH AB One of the consistent features of satellite crustal magnetic anomaly maps is the large negative anomaly in the Indo Eurasian collision zone. This region is modeled by the introduction of magnetic blocks representing the Tibetan, Asian and Himalayan mountain regions. The crustal thickness of these blocks is based on the principle of isostasy. It has been shown that the removal of the core field from the Magsat data removes most of the long-wavelength anomalies associated with the ocean-continent susceptibility contrast, and that some of the observed anomalies, after processing of the satellite data, are a manifestation of this contrast. To account for this, the final model is a superposition of the above block model on a global model of typical continent and ocean susceptibility, called a Standard Earth Magnetization Model (SEMM). A combination of the three blocks superposed on the SEMM reproduces the major features of the observed Magsat anomalies. Block model susceptibilities of the Asian and Himalayan regions are the same as for the continental portion of the SEMM, albeit with a greater crustal thickness. Thus, the crust in these regions is typical. By contrast, the satellite magnetic data require an integrated susceptibility in the Tibetan region which is considerably lower than typical. Two possible explanations are suggested. One, that the origin and tectonic history of the Tibetan region differs from the neighboring regions in such a way as to result in lower susceptibility. This is consistent with current thinking that the Tibetan plateau is made up of several fragments or micro-continents which were attached to Asia prior to the collision of India with Asia. The other possible explanation is that the Curie isotherm in the Tibetan region is elevated compared to the Asian and Himalayan regions. C1 NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. NR 47 TC 7 Z9 8 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD OCT 1 PY 1992 VL 212 IS 1-2 BP 117 EP 127 DI 10.1016/0040-1951(92)90144-U PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU482 UT WOS:A1992JU48200010 ER PT J AU VONFRESE, RRB TAYLOR, PT AF VONFRESE, RRB TAYLOR, PT TI LITHOSPHERIC ANALYSIS OF MAGNETIC AND RELATED GEOPHYSICAL ANOMALIES - PREFACE SO TECTONOPHYSICS LA English DT Editorial Material C1 OHIO STATE UNIV,DEPT GEOL SCI,COLUMBUS,OH 43210. NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. RP VONFRESE, RRB (reprint author), OHIO STATE UNIV,BYRD POLAR RES CTR,COLUMBUS,OH 43210, USA. RI Taylor, Patrick/D-4707-2012 OI Taylor, Patrick/0000-0002-1212-9384 NR 0 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD OCT 1 PY 1992 VL 212 IS 1-2 BP R7 EP R8 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JU482 UT WOS:A1992JU48200001 ER PT J AU MADSEN, BC KHEOH, T HINKLE, CR DRESCHEL, T AF MADSEN, BC KHEOH, T HINKLE, CR DRESCHEL, T TI PRECIPITATION CHEMISTRY IN EAST CENTRAL FLORIDA FROM 1978 TO 1987 SO WATER AIR AND SOIL POLLUTION LA English DT Article ID RAIN-WATER; NETWORK; NITRATE; PH AB Rainfall was collected on the University of Central Florida campus and at the Kennedy Space Center over a 10 yr period between 1978 and 1987. The chemical composition has been determined and summarized by month, annual periods and for the entire ten year record at both locations. The weighted average pH at each site was 4.58; however, annual weighted average pH was above the 10 yr average during 4 of the last 5 years. Annual nitrate concentrations increased slightly during the latter half of the record while the annual excess sulfate concentrations remained below the 10 yr weighted average during 4 of the last 5 years. Stepwise regression suggests that sulfate, nitrate, ammonium ion and Ca played major roles in the description of rainwater acidity. Annual acid deposition and annual rainfall have varied from 20 to 50 meq H+ m-2 yr-1 and 100 to 180 cm yr-1, respectively. Sea salt comprises at least 25% of the total ionic composition. Trends in acidity, excess sulfate concentration and nitrate deposition have been observed in monthly data obtained at UCF. C1 UNIV CENT FLORIDA,DEPT STAT,ORLANDO,FL 32816. BIONET CORP,NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. RP MADSEN, BC (reprint author), UNIV CENT FLORIDA,DEPT CHEM,ORLANDO,FL 32816, USA. OI Dreschel, Thomas/0000-0003-2211-5733 NR 13 TC 6 Z9 6 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0049-6979 J9 WATER AIR SOIL POLL JI Water Air Soil Pollut. PD OCT PY 1992 VL 65 IS 1-2 BP 7 EP 21 DI 10.1007/BF00482746 PG 15 WC Environmental Sciences; Meteorology & Atmospheric Sciences; Water Resources SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences; Water Resources GA JY237 UT WOS:A1992JY23700002 ER PT J AU AMINPOUR, MA AF AMINPOUR, MA TI DIRECT FORMULATION OF A HYBRID 4-NODE SHELL ELEMENT WITH DRILLING DEGREES OF FREEDOM SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article ID FINITE-ELEMENTS AB A simple 4-node assumed-stress hybrid quadrilateral shell element with rotational or 'drilling' degrees of freedom is formulated. The element formulation is based directly on a 4-node element. This direct formulation requires fewer computations than a similar element that is derived from an 'internal' 8-node isoparametric element in which the midside degrees of freedom are eliminated by expressing them in terms of displacements and rotations at corner nodes. The formulation is based on the principle of minimum complementary energy. The membrane part of the element has 12 degrees of freedom, including the drilling degrees of freedom. The bending part of the element also has 12 degrees of freedom. The bending part of the element uses the Reissner Mindlin plate theory which takes into account the transverse shear effects. Quadratic variations for both in-plane and out-of-plane displacement fields and linear variations for both in-plane and out-of-plane rotation fields are assumed along the edges of the element. The element Cartesian-co-ordinate system is selected such as to make the stress field invariant with respect to node numbering. The membrane part of the stress field is based on a 9-parameter equilibrating stress field, while the bending part is based on a 13-parameter equilibrating stress field. The element passes the patch test, is nearly insensitive to mesh distortion, alleviates the 'locking' phenomenon, is invariant with respect to node numbering, has no hidden spurious modes, and produces accurate and reliable results. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. RP ANALYT SERV & MAT INC, 107 RES DR, HAMPTON, VA 23666 USA. NR 34 TC 21 Z9 21 U1 0 U2 1 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0029-5981 EI 1097-0207 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD SEP 30 PY 1992 VL 35 IS 5 BP 997 EP 1013 DI 10.1002/nme.1620350504 PG 17 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA JM513 UT WOS:A1992JM51300003 ER PT J AU VITTA, S STAN, MA WARNER, JD ALTEROVITZ, SA AF VITTA, S STAN, MA WARNER, JD ALTEROVITZ, SA TI MAGNETIC-FLUX RELAXATION IN YBA2CU3O7-X THIN-FILM - THERMAL OR ATHERMAL SO THIN SOLID FILMS LA English DT Article ID HIGH-TEMPERATURE SUPERCONDUCTORS; CREEP; DEPENDENCE; MOTION; FIELD AB The magnetic flux relaxation behavior of YBa2Cu3O7-x thin film on LaAlO3 for H parallel-to c was studied in the range 4.2-40 K and 0.2-1.0 T. Both the normalized flux relaxation rate S and the flux pinning energy U0 exhibit a weak field dependence at low temperatures (T less-than-or-equal-to 20 K). Within this regime S and U0 are observed to increase continuously from 1.0 x 10(-2) to 2.0 x to 10(-2) and 45 to 130 meV respectively, as the temperature T increases from 4.2 to 20 K. While S is observed to decrease in proportion to k T for T less-than-or-equal-to 20 K, it does not extrapolate to zero at T = 0, which is in contradiction to the thermally activated flux creep and vortex glass models. This behavior is discussed in terms of the athermal quantum tunneling of flux lines. The magnetic field dependence of U0, however, is not completely understood. C1 NASA,LEWIS RES CTR,MAIL STOP 54-5,CLEVELAND,OH 44135. RI Vitta, Satish/K-7336-2015 OI Vitta, Satish/0000-0003-4138-0022 NR 19 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0040-6090 J9 THIN SOLID FILMS JI Thin Solid Films PD SEP 30 PY 1992 VL 217 IS 1-2 BP 156 EP 160 DI 10.1016/0040-6090(92)90623-J PG 5 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA JR301 UT WOS:A1992JR30100026 ER PT J AU VITTA, S ALTEROVITZ, SA STAN, MA AF VITTA, S ALTEROVITZ, SA STAN, MA TI THE EFFECT OF FLUCTUATIONS ON THE ELECTRICAL TRANSPORT BEHAVIOR IN YBA2CU3O7-X SO JOURNAL OF PHYSICS-CONDENSED MATTER LA English DT Article ID HIGH-TC SUPERCONDUCTORS; SINGLE-CRYSTALS; THERMODYNAMIC FLUCTUATIONS; ANISOTROPIC RESISTIVITY; PHASE-TRANSITIONS; THIN-FILMS; PARACONDUCTIVITY; CONDUCTIVITY; CROSSOVER; FIELD AB The excess conductivity behaviour of highly oriented YBa2Cu3O7-x thin films prepared by both coevaporation and laser ablation has been studied in detail in the reduced-temperature range 9 x 10(-4) < t < 1. The excess conductivity in all the films studied was found to diverge sharply near T(c), in agreement with the conventional mean-field theory. However, the detailed temperature dependence could not be fitted to either the power-law or the logarithmic functional forms as predicted by the theory. The excess conductivity of all the films was found to be exponentially dependent on the temperature over nearly three decades for 9 x 10(-4) < t < 10(-1), in contradiction to the mean-field theory. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RI Vitta, Satish/K-7336-2015 OI Vitta, Satish/0000-0003-4138-0022 NR 27 TC 0 Z9 0 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-8984 J9 J PHYS-CONDENS MAT JI J. Phys.-Condes. Matter PD SEP 28 PY 1992 VL 4 IS 39 BP 7891 EP 7898 DI 10.1088/0953-8984/4/39/004 PG 8 WC Physics, Condensed Matter SC Physics GA JQ881 UT WOS:A1992JQ88100004 ER PT J AU DAVIS, RL HODGES, HM SMOOT, GF STEINHARDT, PJ TURNER, MS AF DAVIS, RL HODGES, HM SMOOT, GF STEINHARDT, PJ TURNER, MS TI COSMIC MICROWAVE BACKGROUND PROBES MODELS OF INFLATION SO PHYSICAL REVIEW LETTERS LA English DT Article ID EXTENDED INFLATION; UNIVERSE SCENARIO; PERTURBATIONS; RADIATION; FLUCTUATIONS; ANISOTROPY; PRESCRIPTION; CONSTRAINTS; COSMOLOGIES AB Inflation creates both scalar (density) and tensor (gravity wave) metric perturbations. We find that the tensor-mode contribution to the cosmic microwave background anisotropy on large-angular scales can only exceed that of the scalar mode in models where the spectrum of perturbations deviates significantly from scale invariance (e.g., extended and power-law inflation models and extreme versions of chaotic inflation). If the tensor mode dominates at large-angular scales, then the value of DELTAT/T predicted on 1-degrees is less than if the scalar mode dominates, and, for cold-dark-matter models, bias factors b > 1 can be made consistent with Cosmic Background Explorer (COBE) DMR results. C1 LAWRENCE BERKELEY LAB,SPACE SCI LAB,BERKELEY,CA 94720. LAWRENCE BERKELEY LAB,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637. FERMI NATL ACCELERATOR LAB,FERMILAB ASTROPHYS CTR,NASA,BATAVIA,IL 60510. RP DAVIS, RL (reprint author), UNIV PENN,DEPT PHYS,PHILADELPHIA,PA 19104, USA. NR 24 TC 184 Z9 184 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 SEP 28 PY 1992 VL 69 IS 13 BP 1856 EP 1859 DI 10.1103/PhysRevLett.69.1856 PG 4 WC Physics, Multidisciplinary SC Physics GA JP859 UT WOS:A1992JP85900007 ER PT J AU GELB, JM KWONG, W ROSEN, SP AF GELB, JM KWONG, W ROSEN, SP TI IMPLICATIONS OF NEW GALLEX RESULTS FOR THE MIKHEYEV-SMIRNOV-WOLFENSTEIN SOLUTION OF THE SOLAR NEUTRINO PROBLEM SO PHYSICAL REVIEW LETTERS LA English DT Article ID POSSIBLE EXPLANATION; REAL-TIME; OSCILLATIONS; MATTER; EARTH; REGENERATION; PUZZLE AB We compare the implications for Be-7 and pp neutrinos of the two Mikheyev-Smirnov-Wolfenstein fits to the new GALLEX solar neutrino measurements. Small-mixing-angle solutions tend to suppress the former as electron neutrinos, but not the latter, and large-angle solutions tend to reduce both by about a factor of 2. The consequences for BOREXINO and similar solar neutrino-electron scattering experiments are discussed. C1 UNIV TEXAS,DEPT PHYS,ARLINGTON,TX 76019. RP GELB, JM (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510, USA. NR 35 TC 17 Z9 17 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 SEP 28 PY 1992 VL 69 IS 13 BP 1864 EP 1866 DI 10.1103/PhysRevLett.69.1864 PG 3 WC Physics, Multidisciplinary SC Physics GA JP859 UT WOS:A1992JP85900009 ER PT J AU CRISP, J BARTHOLOMEW, MJ AF CRISP, J BARTHOLOMEW, MJ TI MIDINFRARED SPECTROSCOPY OF PAHALA ASH PALAGONITE AND IMPLICATIONS FOR REMOTE-SENSING STUDIES OF MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SPECTRAL REFLECTANCE; OPTICAL-CONSTANTS; SOIL AB Remote sensing of Mars at mid-infrared wavelengths could be used to identify different silicate rocks and minerals. Current knowledge suggests that the primary components of the surface of Mars are basaltlike rocks and a palagonitelike dust. To study the mid-infrared (7-20 mum) spectroscopy of this combination of materials, we examined the influence of Pahala ash palagonite on the biconical reflectance of quartzite and basalt. The reflectance of the palagonite is flat and low (1-2%), unlike the reflectance of quartzite and basalt. The reflectance of quartzite or basalt is significantly reduced by the addition of small amounts of the palagonite dust. A dusting of 1-20 mum palagonite particles and 20-250 Am particle clumps, covering 50% of the quartzite host, reduces the quartzite mid-infrared reflectance by 50%, as expected for an essentially black coating. Similar data were obtained for basalt. Even for extremely small amounts of palagonite (2-100 mum thickness, averaging 5 mum), the reflectance of the underlying rock is linearly related to exposed surface area. To confirm the opaque behavior of the Pahala ash palagonite coatings, we estimated the imaginary part (k) of the refractive index from transmission measurements. The strong absorption and low reflectance (high emissivity) of the palagonite at 8-11 mum and 17-25 mum explain its opaque behavior. Estimates of the extinction coefficient indicate that even a 5-mum thickness of Pahala ash palagonite is optically thick in these wavelength ranges where silicate rock identification is critical. Thus mid-infrared remote sensing of rocks on Mars will be practical only for dust-free areas. C1 JET PROP LAB,PASADENA,CA 91109. RI Crisp, Joy/H-8287-2016 OI Crisp, Joy/0000-0002-3202-4416 NR 42 TC 25 Z9 25 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1992 VL 97 IS E9 BP 14691 EP 14699 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KG491 UT WOS:A1992KG49100002 ER PT J AU BURDIK, C CUMMINS, CJ GASKELL, RW SHARP, RT AF BURDIK, C CUMMINS, CJ GASKELL, RW SHARP, RT TI COMPLETE BRANCHING-RULES GENERATING FUNCTION FOR SO(7) SUPERSET-OF SU(2)3 AND POLYNOMIAL BASIS STATES SO JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL LA English DT Article ID CHARACTER GENERATORS; LIE-GROUPS; REPRESENTATIONS AB A branching rules generating function is given for SO(7) superset-of SU(2)3, along with its interpretation in terms of basis states, and instructions for calculating generator matrix elements. The generator matrix elements for the degenerate (0, 0, c) representations are calculated as an example of this procedure. C1 CONCORDIA UNIV, DEPT MATH & STAT, MONTREAL H3G 1M8, QUEBEC, CANADA. JET PROP LAB, PASADENA, CA 91109 USA. MCGILL UNIV, DEPT PHYS, MONTREAL H3A 2T8, QUEBEC, CANADA. RP BURDIK, C (reprint author), CHARLES UNIV, FAC MATH & PHYS, CTR NUCL, V HOLESOVICKACH 2, CS-18000 PRAGUE 8, CZECHOSLOVAKIA. NR 15 TC 2 Z9 2 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0305-4470 J9 J PHYS A-MATH GEN JI J. Phys. A-Math. Gen. PD SEP 21 PY 1992 VL 25 IS 18 BP 4835 EP 4846 DI 10.1088/0305-4470/25/18/017 PG 12 WC Physics, Multidisciplinary; Physics, Mathematical SC Physics GA JQ526 UT WOS:A1992JQ52600017 ER PT J AU ROMANS, LJ AF ROMANS, LJ TI SUPERSYMMETRIC, COLD AND LUKEWARM BLACK-HOLES IN COSMOLOGICAL EINSTEIN-MAXWELL THEORY SO NUCLEAR PHYSICS B LA English DT Article ID GAUGED EXTENDED SUPERGRAVITY; DE-SITTER SPACE; QUANTUM WORMHOLES; PARTICLE CREATION; POSITIVE ENERGY; STRING THEORY; STABILITY; THERMODYNAMICS; BACKGROUNDS; GRAVITY AB In asymptotically flat (AF) space, the extreme Reissner-Nordstrom (RN) black hole is distinguished by its coldness (vanishing Hawking temperature) and its supersymmetry. We examine RN solutions to Einstein-Maxwell theory with a cosmological constant LAMBDA, classifying the cold black holes and, for positive LAMBDA, the "lukewarm" black holes at the same temperature as the de Sitter thermal background. For negative LAMBDA, we classify the supersymmetric solutions within the context of N = 2 gauged supergravity. One finds supersymmetric analogues of AF-space extreme RN black holes, which for nonzero LAMBDA differ from the cold black holes. In addition, these is an exotic class of supersymmetric solutions which cannot be continued to asymptotically flat space. since the magnetic charge becomes infinite in that limit. RP ROMANS, LJ (reprint author), JET PROP LAB,301-150,PASADENA,CA 91109, USA. NR 42 TC 196 Z9 196 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0550-3213 J9 NUCL PHYS B JI Nucl. Phys. B PD SEP 21 PY 1992 VL 383 IS 1-2 BP 395 EP 415 DI 10.1016/0550-3213(92)90684-4 PG 21 WC Physics, Particles & Fields SC Physics GA JT151 UT WOS:A1992JT15100017 ER PT J AU SKIBO, JG RAMATY, R LEVENTHAL, M AF SKIBO, JG RAMATY, R LEVENTHAL, M TI DIFFUSE 0.511 MEV LINE EMISSION AND THE DISTRIBUTION OF POSITRON-ANNIHILATION IN THE GALAXY SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, GENERAL; GAMMA-RAYS, THEORY; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES ID GALACTIC-CENTER DIRECTION; GAMMA-RAY LINE; RADIAL-DISTRIBUTION; CENTER REGION; INTERSTELLAR-MEDIUM; MOLECULAR CLOUDS; MILKY-WAY; IRON LINE; CO SURVEY; 1E1740.7-2942 AB We model the distribution in the Galaxy of 0.511 MeV line emission and the implied positron annihilation using plausible distributions based on observations at other photon energies. We use 0.511 MeV line observations from the Galactic center and from directions away from the Galactic center to normalize the two-dimensionaal 0.511 MeV sky maps. We find that in order to understand all of the available data it is necessary to invoke the presence of a time-variable component of 0.511 MeV line emission in addition to an underlying diffuse component. The large 0.511 MeV fluxes observed with broad field of view detectors, such as the SMM gamma-ray spectrometer, can be reconciled with the small fluxes seen with narrow field-of-view instruments (GRIS and OSSE) from directions away from the Galactic center if the diffuse emission follows the distribution of Galactic novae for which the recently detected 0.511 MeV line emission from the Galactic center with OSSE is predominantly of diffuse origin. For future GRIS and HEXAGONE observations from the direction of the Galactic center we predict a minimum 0.511 MeV line flux of (6.0 +/- 0.9) x 10(-4) photons cm-2 s-1. C1 NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY PHYS LAB, GREENBELT, MD 20771 USA. NR 61 TC 18 Z9 18 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1992 VL 397 IS 1 BP 135 EP 147 DI 10.1086/171772 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM989 UT WOS:A1992JM98900015 ER PT J AU WU, KW CHANMUGAM, G SHAVIV, G AF WU, KW CHANMUGAM, G SHAVIV, G TI PROPERTIES OF QUASI-PERIODIC OSCILLATIONS IN ACCRETING MAGNETIC WHITE-DWARFS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; HYDRODYNAMICS; STARS, MAGNETIC FIELDS; STARS, OSCILLATIONS; WHITE DWARFS ID TIME-DEPENDENT ACCRETION; RADIATIVE SHOCK-WAVES; STABILITY PROPERTIES; X-RAY; EMISSION; INSTABILITY; VARIABILITY; E1405-451; STARS AB Previous studies of time-dependent accretion onto magnetic white dwarfs, in which the cooling was assumed to be due to bremsstrahlung emission, have shown that the accretion shock undergoes oscillations. However, when cyclotron cooling is also included, the oscillations are damped for sufficiently strong magnetic fields. Here we demonstrate that the oscillations can be sustained by accretion-fluctuation-induced excitations. The frequency of the QPOs are shown to increase quadratically with the magnetic field strength. We interpret the oscillations as a two-phase process in which bremsstrahlung cooling dominates in one half-cycle and cyclotron cooling in the other. Such a process may have very different consequences compared to a single-phase process where the functional form of the cooling is essentially the same throughout the cycle. If in the two-phase process damping occurs mainly in the cyclotron cooling half-cycle, there will be a universal effective damping factor which tends to suppress all oscillation modes indiscriminately. The oscillations of the accretion shock also could be a limit cycle process in which the system vacillates between two branches. C1 LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803. TECHNION ISRAEL INST TECHNOL,ASHER SPACE RES INST,IL-32000 HAIFA,ISRAEL. TECHNION ISRAEL INST TECHNOL,DEPT PHYS,IL-32000 HAIFA,ISRAEL. RP WU, KW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-65,HUNTSVILLE,AL 35812, USA. NR 35 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1992 VL 397 IS 1 BP 232 EP 241 DI 10.1086/171782 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM989 UT WOS:A1992JM98900025 ER PT J AU ROBERT, C MOFFAT, AFJ DRISSEN, L LAMONTAGNE, R SEGGEWISS, W NIEMELA, VS CERRUTI, MA BARRETT, P BAILEY, J GARCIA, J TAPIA, S AF ROBERT, C MOFFAT, AFJ DRISSEN, L LAMONTAGNE, R SEGGEWISS, W NIEMELA, VS CERRUTI, MA BARRETT, P BAILEY, J GARCIA, J TAPIA, S TI PHOTOMETRY, POLARIMETRY, SPECTROSCOPY, AND SPECTROPOLARIMETRY OF THE ENIGMATIC WOLF-RAYET STAR EZ CANIS MAJORIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, SPECTROSCOPIC; POLARIZATION; STARS, INDIVIDUAL (EZ CANIS MAJORIS); STARS, WOLF-RAYET ID VELOCITY INTERSTELLAR GAS; LINEAR-POLARIZATION; SPECTRAL-ANALYSIS; STELLAR WINDS; BINARY NATURE; LIGHT CURVES; HD-50896; EMISSION; MASS; DISK AB We present new multimode data collected since 1987 for the peculiar Wolf-Rayet star EZ CMa. The continuum photometry and polarimetry show periodic variations consistent with the previously known 3.766 day period. As before, the shapes of the light and polarization curves change from one epoch to another. A periodicity search was carried out on the amplitude of the light curves in an attempt to understand the epoch-to-epoch changes. The result was inconclusive. Linear polarization data were well fitted with an eccentric binary model where an additional free parameter was included to allow for epoch-dependent changes of the geometrical electron distribution in the W-R envelope. This yielded a set of basic parameters including the eccentricity, e = 0.39 +/- 0.02, and the orbital inclination, i = 114-degrees +/- 3-degrees, which appear to remain constant within their errors for most data sets. The spectroscopic data show global profile variations for all three observed strong emission lines He II lambda-5412, C IV lambda-5807, and He I lambda-5876. Periodicity of these variations was not obvious. Radial velocities of the lines vary with the 3.766 day period. Nevertheless, it is not clear whether these are strictly due to systematic line motion as expected in a binary system. Radially expanding inhomogeneities are also seen superposed on the line profiles. Variable polarization in the lines is also observed. We searched for a correlation in the variability seen in different modes of observation; the situation is confused by a lack of sufficient simultaneity. Finally, we discuss all the results from two points of view: a W-R + c binary system and a rotating single star. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. OBSERV ASTRON MT MEGANTIC,MONTREAL H3C 3J7,QUEBEC,CANADA. UNIV MONTREAL,DEPT PHYS,MONTREAL H3C 3J7,QUEBEC,CANADA. UNIV STERNWARTE BONN,OBSERVATORIUM HOHER LIST,W-5568 DAUN,GERMANY. INST ASTRON & FIS ESPACIO,RA-1428 BUENOS AIRES,ARGENTINA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNITED KINGDOM INFRARED TELESCOPE,HILO,HI 96720. UNIV TORONTO,SO OBSERV,LAS CAMPANAS,CHILE. MIT,LINCOLN LAB,LEXINGTON,MA 02173. NR 79 TC 50 Z9 50 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 SEP 20 PY 1992 VL 397 IS 1 BP 277 EP 303 DI 10.1086/171786 PN 1 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM989 UT WOS:A1992JM98900029 ER PT J AU JEFFERY, DJ LEIBUNDGUT, B KIRSHNER, RP BENETTI, S BRANCH, D SONNEBORN, G AF JEFFERY, DJ LEIBUNDGUT, B KIRSHNER, RP BENETTI, S BRANCH, D SONNEBORN, G TI ANALYSIS OF THE PHOTOSPHERIC EPOCH SPECTRA OF TYPE-IA SUPERNOVAE SN-1990N AND SN-1991T SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ABUNDANCES; SUPERNOVAE, INDIVIDUAL (SN-1990N, SN-1991T); TECHNIQUES, SPECTROSCOPIC ID WHITE-DWARF MODELS; SOBOLEV-P METHOD; ABSOLUTE-MAGNITUDE; EXPANDING ATMOSPHERES; LINE-PROFILES; SN-1987A; DEFLAGRATION; POLARIZATION; NOVAE; LIGHT AB An analysis of the photospheric epoch optical and UV spectra (obtained with the IUE satellite) of Type Ia supernovae SN 1990N and SN 1991T is presented. To perform the analysis, synthetic spectra calculated using an LTE radiative transfer procedure and white dwarf explosion models of Type la supernovae were fitted to the observations. For both supernovae, the observed spectra are consistent with a white dwarf explosion model that possesses a core of newly synthesized iron peak elements, a core boundary moving at approximately 9000 km s-1, and an envelope with a composition of intermediate-mass elements. In the well known white dwarf explosion model W7, the inner envelope (i.e., matter with velocities in the range approximately 9000-15,000 km s-1) consists of newly synthesized elements produced as the burning front of the explosion died out. For SN 1990N the observed spectra are consistent with a composition of the inner envelope that is like that of model W7. For SN 1991T the observed spectra suggest that the inner envelope of this supernova has silicon underabundant by a factor of order 3 and calcium underabundant by a factor of order 10 relative to model W7. The near-UV spectra (2500-3500 angstrom) for both supernovae are best fitted by assuming that there are iron peak elements in the ejecta moving at velocities greater than 15,000 km s-1 (i.e., in the outer envelope) and that these iron peak elements are dominated by newly synthesized Ni-Co. This result is inconsistent with the model W7 prediction of an outer envelope consisting of unburned matter dominated by carbon and oxygen. The absolute abundance of intermediate-mass elements in the outer ejecta is quite uncertain for both supernovae, but spectrum fitting shows that abundances higher than solar are probable and suggests that silicon, sulfur, and calcium are underabundant in SN 1991T relative to SN 1990N by factors of order 3, 3, and 10, respectively. In the case of SN 1990N, there are ejecta moving at a velocity of approximately 40,000 km s-1 and newly synthesized material moving perhaps as fast as 25,000 km s-1. SN 1991T has matter moving at least as fast as approximately 20,000 km s-1. Model W7 has no ejecta moving faster than 22,027 km s-1. Some variation on model W7 or the delayed/late detonation models for Type Ia supernovae may be able to explain the high velocities required for SN 1990N and the newly synthesized elements that are probably present in the outer ejecta of both supernovae. The synthetic spectra calculated for the analysis and the expanding photosphere method are used for absolute B maximum and distance determinations for SN 1990N and SN 1991T. C1 UNIV OKLAHOMA, DEPT PHYS & ASTRON, NORMAN, OK 73019 USA. NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP JEFFERY, DJ (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS, MS-19, 60 GARDEN ST, CAMBRIDGE, MA 02138 USA. OI Benetti, Stefano/0000-0002-3256-0016 NR 111 TC 111 Z9 111 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1992 VL 397 IS 1 BP 304 EP 328 DI 10.1086/171787 PN 1 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM989 UT WOS:A1992JM98900030 ER PT J AU MOORE, RL HAMMER, R MUSIELAK, ZE SUESS, ST AN, CH AF MOORE, RL HAMMER, R MUSIELAK, ZE SUESS, ST AN, CH TI A NEW WAY TO CONVERT ALFVEN WAVES INTO HEAT IN SOLAR CORONAL HOLES - INTERMITTENT MAGNETIC-LEVITATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SOLAR WIND; SUN, CORONA AB In our recent analysis of Alfven wave reflection in solar coronal holes, we found evidence that coronal holes are heated by reflected Alfven waves. This result suggests that the reflection is inherent to the process that dissipates these Alfven waves into heat. We propose a novel dissipation process ("intermittent magnetic levitation") that is driven by the reflection, and that plausibly dominates the heating in coronal holes. C1 KIEPENHEUER INST SONNENPHYS,W-7800 FREIBURG,GERMANY. UNIV ALABAMA,HUNTSVILLE,AL 35899. APPL RES INC,HUNTSVILLE,AL 35805. RP MOORE, RL (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 6 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1992 VL 397 IS 1 BP L55 EP L58 DI 10.1086/186543 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM990 UT WOS:A1992JM99000014 ER PT J AU COFER, WR STEVENS, RK WINSTEAD, EL PINTO, JP SEBACHER, DI ABDULRAHEEM, MY ALSAHAFI, M MAZUREK, MA RASMUSSEN, RA CAHOON, DR LEVINE, JS AF COFER, WR STEVENS, RK WINSTEAD, EL PINTO, JP SEBACHER, DI ABDULRAHEEM, MY ALSAHAFI, M MAZUREK, MA RASMUSSEN, RA CAHOON, DR LEVINE, JS TI KUWAITI OIL FIRES - COMPOSITIONS OF SOURCE SMOKE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID BOREAL FOREST FIRES; EMISSIONS AB While the Kuwaiti oil-fire smoke plumes manifested a pronounced impact on solar radiation in the Gulf region (visibility, surface temperatures, etc.), smoke plume concentrations of combustion-generated pollutants suggest that the overall chemical impact on the atmosphere of the smoke from these fires was probably much less than anticipated. Combustion in the Kuwaiti oil fires was surprisingly efficient, releasing on average more than 93% of the combusted hydrocarbon fuels as carbon dioxide (CO2). Correspondingly, combustion-produced quantities of carbon monoxide (CO) and carbonaceous particles were low, each approximately 2% by weight. The fraction of methane (CH4) produced by the fires was also relatively low (approximately 0.2%), but source emissions of nonmethane hydrocarbons were high (approximately 2%). Processes other than combustion (e.g., volatilization) probably contributed significantly to the measured in-plume hydrocarbon concentrations. Substantially different elemental to organic carbon ratios were obtained for aerosol particles from several different types of fires/smokes. Sulfur emissions (particulate and gaseous) measured at the source fires were lower (approximately 0.5%) than predicted based on average sulfur contents in the crude. Sulfur dioxide measurements (SO2) reported herein, however, were both limited in actual number and in the number of well fires sampled. Nitrous oxide (N2O) emissions from the Kuwaiti oil fires were very low and often could not be distinguished from background concentrations. About 25-30% of the fires produced white smoke plumes that were found to be highly enriched in sodium and calcium chlorides. C1 US EPA,ATMOSPHER RES & EXPOSURE ASSESSMENT LAB,RES TRIANGLE PK,NC 27711. HUGHES STX CORP,HAMPTON,VA. KUWAIT ENVIRONM PROTECT DEPT,KUWAIT,KUWAIT. OREGON GRAD INST SCI & TECHNOL,GLOBAL CHANGE RES CTR,BEAVERTON,OR. BROOKHAVEN NATL LAB,DEPT APPL SCI,UPTON,NY 11973. RP COFER, WR (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 18 TC 16 Z9 16 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-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1992 VL 97 IS D13 BP 14521 EP 14525 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JP896 UT WOS:A1992JP89600007 ER PT J AU PILEWSKIE, P VALERO, FPJ AF PILEWSKIE, P VALERO, FPJ TI RADIATIVE EFFECTS OF THE SMOKE CLOUDS FROM THE KUWAIT OIL FIRES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ARCTIC HAZE; CLIMATE; WELLS AB The radiative effects of the smoke from the Kuwait oil fires were assessed by measuring downwelling and upwelling solar flux, as well as spectral solar extinction beneath, above, and within the smoke plume. Radiative flux divergence measurements were made to determine smoke-induced heating and cooling rates. Seven radiation flight missions were undertaken between May 16 and June 2, 1991, to characterize the plume between the source region in Kuwait and approximately 200 km south, near Manama, Bahrain. We present results from one flight representative of conditions of the composite plume. On May 18, 1991, in a homogeneous, well-mixed region of smoke approximately 100 km downstream of the fires, visible optical depths as high as 2 were measured, at which time transmission to the surface was 8%, while 78% of the solar radiation was absorbed by the smoke. The calculated instantaneous heating Tate inside the plume reached 24 K/d. While these effects are probably typical of those regions in the Persian Gulf area directly covered by the smoke, there is no evidence to suggest significant climatic effects in other regions. RP PILEWSKIE, P (reprint author), NASA,AMES RES CTR,ATMOSPHER PHYS RES BRANCH,DIV EARTH SYST SCI,MS 245-4,MOFFETT FIELD,CA 94035, USA. NR 13 TC 15 Z9 15 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 SEP 20 PY 1992 VL 97 IS D13 BP 14541 EP 14544 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JP896 UT WOS:A1992JP89600011 ER PT J AU KING, MD AF KING, MD TI DIRECTIONAL AND SPECTRAL REFLECTANCE OF THE KUWAIT OIL-FIRE SMOKE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SCATTERING; WELLS AB The angular reflectance pattern of the Kuwait oil-fire smoke was measured from an aircraft at 13 discrete wavelengths between 0.5 and 2.3 mum. Measurements at 0.75 and 1.64 mum showed that the reflectance of the smoke layer was about 12% in the nadir direction with considerable limb brightening toward the horizon. Furthermore, these observations revealed a backscattering maximum in the antisolar direction and an enhanced scattering near the rainbow direction. These characteristics suggest that the smoke layer 90 km downwind of the Kuwait oil fires was composed of a significant number of oil drizzle droplets that scatter solar radiation as a layer composed of spherical particles. RP KING, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. RI King, Michael/C-7153-2011 OI King, Michael/0000-0003-2645-7298 NR 20 TC 12 Z9 12 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-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1992 VL 97 IS D13 BP 14545 EP 14549 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JP896 UT WOS:A1992JP89600012 ER PT J AU CAHALAN, RF AF CAHALAN, RF TI THE KUWAIT OIL FIRES AS SEEN BY LANDSAT SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB A mosaic of two Landsat thematic mapper images acquired May 30, 1991, reveals a dark smoke plume 30-60 km wide extending hundreds of kilometers south of Kuwait City along the Persian Gulf. Smoke coming from the Raudhatain and Sabriyah oil fields blew across the Gulf of Kuwait and over Kuwait City, joined with smoke from the Greater Burgan and Minagish fields, and continued southward over smaller villages and regions of desert agriculture consisting of hundreds of axially irrigated fields in both Kuwait and Saudi Arabia. One agricultural region in Kuwait was completely obscured by the smoke. The light colored limestone gravel and sand surface was darkened by oil lakes near the wells, and by oil drizzling out of the plume downwind of the wells. Most fires produced either a light or dark plume, and the separate plumes mixed to form a combined plume much darker than the land surface, but slightly more reflective than the Gulf waters. A few of the hottest fires had no visible plume, and are presumably associated with methane combustion. The last of the Kuwait fires was reportedly extinguished in November of 1991. Continued monitoring is needed to assess the impact of emissions from both burning and nonburning oil wells on the region's climate, as well as on the agriculture, fishing, and other activities essential to life in the region. RP CAHALAN, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 10 TC 8 Z9 9 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 SEP 20 PY 1992 VL 97 IS D13 BP 14565 EP 14571 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JP896 UT WOS:A1992JP89600014 ER PT J AU KAUFMAN, YJ SETZER, A WARD, D TANRE, D HOLBEN, BN MENZEL, P PEREIRA, MC RASMUSSEN, R AF KAUFMAN, YJ SETZER, A WARD, D TANRE, D HOLBEN, BN MENZEL, P PEREIRA, MC RASMUSSEN, R TI BIOMASS BURNING AIRBORNE AND SPACEBORNE EXPERIMENT IN THE AMAZONAS (BASE-A) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SCALE AIR-POLLUTION; TROPOSPHERIC OZONE; SATELLITE MEASUREMENTS; EMISSIONS; AEROSOLS; TROPICS; BRAZIL; ATMOSPHERE; CLIMATE; CARBON AB In the Biomass Burning Airborne and Spaceborne Experiment in the Amazonas (BASE-A). conducted in September 1989, trace gas and particulate matter emissions were measured from biomass burning due to deforestation and grassland fires in South America. This information is required for a better understanding of the environmental impacts of biomass burning in the tropics and to improve algorithms for remote sensing of biomass burning from satellite platforms. The field experiment utilized the twin-engine Embraer Bandeirante EMB-101 instrumented aircraft of the Brazilian Institute for Space Research (INPE). Concentrations of ozone, CO2, CO, CH4, and particulate matter were measured from the aircraft. Fires were observed from satellite imagery, and the smoke optical thickness, particle size, and profiles of the extinction coefficient were measured using sunphotometers in the aircraft and from the ground. Four smoke plumes were sampled, three vertical profiles were measured, and extensive ground measurements were conducted of smoke optical characteristics for different smoke types. The collected data were analyzed for determining the emission ratios and combustion efficiency (the efficiency of a fire to convert the total burned carbon to carbon dioxide) and were compared with the results from fires in North America. Combustion efficiency was found to be higher in the tropics (97% for the cerrado and 90% for the deforestation fires) with emission factors similar to those of North American fires, for a given combustion efficiency. A strong relation was found between the spatial distribution of fires (up to 9000 per day in one state) and ozone concentration (up to 80 ppbv) and between biomass burning and concentrations of trace gases, particulate matter, and ozone. These relations strongly suggest a correlation between biomass burning in the tropics and ozone formation. An optical model of the smoke aerosol was derived and applied to radiance measurements. The smoke single scattering albedo was computed from the graphitic carbon concentration (assuming external mode mixture) as 0.90 +/- 0.01. The particles effective radii were 0.1 to 0.2 mum except for 1-day aged smoke with values up to 0.4 mum. Radiance measurements indicate that the width of the particle size distribution may be smaller in the tropics than for North American fires. The measured optical properties of smoke and the high correlation between emitted trace gases and particles form a basis for remote sensing of radiatively important trace gases and particulate matter from biomass burning using AVHRR imagery. C1 INST PESQUISAS ESPACIAIS,SAO JOSE CAMPOS,SP,BRAZIL. NOAA,NATL ENVIRONM SATELLITE DATA & INFORMAT SERV,SATELLITE APPL LAB,MADISON,WI. US FOREST SERV,FIRE CHEM,MISSOULA,MT. OREGON GRAD INST SCI & TECHNOL,BEAVERTON,OR. RP KAUFMAN, YJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MAIL CODE 923,GREENBELT,MD 20771, USA. RI Menzel, W. Paul/B-8306-2011 OI Menzel, W. Paul/0000-0001-5690-1201 NR 79 TC 147 Z9 152 U1 1 U2 19 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 SEP 20 PY 1992 VL 97 IS D13 BP 14581 EP 14599 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JP896 UT WOS:A1992JP89600016 ER PT J AU WARD, DE SUSOTT, RA KAUFFMAN, JB BABBITT, RE CUMMINGS, DL DIAS, B HOLBEN, BN KAUFMAN, YJ RASMUSSEN, RA SETZER, AW AF WARD, DE SUSOTT, RA KAUFFMAN, JB BABBITT, RE CUMMINGS, DL DIAS, B HOLBEN, BN KAUFMAN, YJ RASMUSSEN, RA SETZER, AW TI SMOKE AND FIRE CHARACTERISTICS FOR CERRADO AND DEFORESTATION BURNS IN BRAZIL - BASE-B EXPERIMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID BIOMASS; EMISSIONS; HYDROCARBON; CHEMISTRY; AMAZONIA; TROPICS; CLIMATE; IMPACT; CYCLES; TRENDS AB Fires of the tropical forests and savannas are a major source of particulate matter and trace gases affecting the atmosphere globally. A paucity of quantitative information exists for these ecosystems with respect to fuel biomass, smoke emissions, and fire behavior conditions affecting the release of emissions. Five test fires were performed during August and September 1990 in the cerrado (savannalike region) in central Brazil (three fires) and tropical moist forest (two fires) in the eastern Amazon. This paper details the gases released, the ratios of the gases to each other and to particulate matter, fuel loads and the fraction consumed (combustion factors), and the fire behavior associated with biomass consumption. Models are presented for evaluating emission factors for CH4, CO2, CO, H-2, and particles less than 2.5 mum diameter (PM2.5) as a function of combustion efficiency. The ratio of carbon released as CO2 (combustion efficiency) for the cerrado fires averaged 0.94 and for the deforestation fires it decreased from 0.88 for the flaming phase to <0.80 during the smoldering phase of combustion. For tropical ecosystems, emissions of most products of incomplete combustion are projected to be lower than previous estimates for savanna ecosystems and somewhat higher for fires used for deforestation purposes. C1 INST NACL PESQUISAS ESPACIAIS,SAO JOSE CAMPOS,SP,BRAZIL. OREGON GRAD INST SCI & TECHNOL,BEAVTON,OR. OREGON STATE UNIV,DEPT RANGELAND RESOURCES,CORVALLIS,OR 97330. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INST BRASILEIRO GEORG & ESTATIST,RESERVA ECOL,BRASILIA,DF,BRAZIL. RP WARD, DE (reprint author), US FOREST SERV,INTERMT RES STN,POB 8089,MISSOULA,MT 59807, USA. NR 59 TC 191 Z9 195 U1 2 U2 33 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 SEP 20 PY 1992 VL 97 IS D13 BP 14601 EP 14619 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JP896 UT WOS:A1992JP89600017 ER PT J AU BELTON, MJS VEVERKA, J THOMAS, P HELFENSTEIN, P SIMONELLI, D CHAPMAN, C DAVIES, ME GREELEY, R GREENBERG, R HEAD, J MURCHIE, S KLAASEN, K JOHNSON, TV MCEWEN, A MORRISON, D NEUKUM, G FANALE, F ANGER, C CARR, M PILCHER, C AF BELTON, MJS VEVERKA, J THOMAS, P HELFENSTEIN, P SIMONELLI, D CHAPMAN, C DAVIES, ME GREELEY, R GREENBERG, R HEAD, J MURCHIE, S KLAASEN, K JOHNSON, TV MCEWEN, A MORRISON, D NEUKUM, G FANALE, F ANGER, C CARR, M PILCHER, C TI GALILEO ENCOUNTER WITH 951 GASPRA - 1ST PICTURES OF AN ASTEROID SO SCIENCE LA English DT Article ID SURFACE; PHOBOS; FEATURES; DEIMOS AB Galileo images of Gaspra reveal it to be an irregularly shaped object (19 by 12 by 11 kilometers) that appears to have been created by a catastrophic collisional disruption of a precursor parent body. The cratering age of the surface is about 200 million years. Subtle albedo and color variations appear to correlate with morphological features: Brighter materials are associated with craters especially along the crests of ridges, have a stronger 1-micrometer absorption, and may represent freshly excavated mafic materials; darker materials exhibiting a significantly weaker 1-micrometer absorption appear concentrated in interridge areas. One explanation of these patterns is that Gaspra is covered with a thin regolith and that some of this material has migrated downslope in some areas. C1 CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853. NATL OPT ASTRON OBSERV,TUCSON,AZ 85719. PLANETARY SCI INST,TUCSON,AZ 85719. RAND CORP,SANTA MONICA,CA 90406. ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. BROWN UNIV,DEPT GEOL,PROVIDENCE,RI 02912. JET PROP LAB,PASADENA,CA 91109. US GEOL SURVEY,FLAGSTAFF,AZ 86001. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA HEADQUARTERS,WASHINGTON,DC 20546. DFVLR,W-8031 OBERPFAFFENHOFEN,GERMANY. UNIV HAWAII,INST GEOPHYS,HONOLULU,HI 96822. INST SPACE & TERR SCI,CONCORD L4K 3C8,ONTARIO,CANADA. US GEOL SURVEY,MENLO PK,CA 94025. RI Murchie, Scott/E-8030-2015 OI Murchie, Scott/0000-0002-1616-8751 NR 55 TC 151 Z9 151 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 18 PY 1992 VL 257 IS 5077 BP 1647 EP 1652 DI 10.1126/science.257.5077.1647 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JN501 UT WOS:A1992JN50100021 PM 17841160 ER PT J AU BOSELA, PA FERTIS, DG SHAKER, FJ AF BOSELA, PA FERTIS, DG SHAKER, FJ TI GROUNDING OF SPACE STRUCTURES SO COMPUTERS & STRUCTURES LA English DT Article AB Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the 'blanket' of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as 'grounding', or false stiffening, of the stiffness matrix occurs during rigid body rotation. This paper examines the grounding phenomenon in detail. Numerous stiffness matrices developed by others are examined for rigid body rotation capability, and found lacking. A force imbalance inherent in the formulations examined is the likely cause of the grounding problem, suggesting the need for a directed force formulation. C1 NASA,LEWIS RES CTR,DYNAM BRANCH,DIV STRUCT SYST,ENGN DIRECTORATE,CLEVELAND,OH 44135. UNIV AKRON,DEPT CIVIL ENGN,AKRON,OH 44325. RP BOSELA, PA (reprint author), CLEVELAND STATE UNIV,DEPT ENGN TECHNOL,CLEVELAND,OH 44115, USA. NR 16 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 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD SEP 17 PY 1992 VL 45 IS 1 BP 143 EP 153 DI 10.1016/0045-7949(92)90351-Y PG 11 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA JV635 UT WOS:A1992JV63500013 ER PT J AU BOSELA, PA FERTIS, DG SHAKER, FJ AF BOSELA, PA FERTIS, DG SHAKER, FJ TI A NEW PRELOADED BEAM GEOMETRIC STIFFNESS MATRIX WITH FULL RIGID BODY CAPABILITIES SO COMPUTERS & STRUCTURES LA English DT Article AB Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the 'blanket' of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as 'grounding, or false stiffening, of the stiffness matrix occurs during rigid body rotation. The authors have previously shown that the grounding phenomenon is caused by a lack of rigid body rotational capability, and is typical in beam geometric stiffness matrices formulated by others, including those which contain higher order effects. The cause of the problem was identified as the force imbalance inherent in the formulations. In this paper, the authors develop a beam geometric stiffness matrix for a directed force problem, and show that the resultant global stiffness matrix contains complete rigid body mode capabilities, and performs very well in the diagonalization methodology customarily used in dynamic analysis. C1 NASA,LEWIS RES CTR,DYNAM BRANCH,DIV STRUCT SYST,ENGN DIRECTORATE,CLEVELAND,OH 44135. UNIV AKRON,DEPT CIVIL ENGN,AKRON,OH 44325. RP BOSELA, PA (reprint author), CLEVELAND STATE UNIV,DEPT ENGN TECHNOL,CLEVELAND,OH 44115, USA. NR 6 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD SEP 17 PY 1992 VL 45 IS 1 BP 155 EP 163 DI 10.1016/0045-7949(92)90352-Z PG 9 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA JV635 UT WOS:A1992JV63500014 ER PT J AU FRIEDL, RR SANDER, SP YUNG, YL AF FRIEDL, RR SANDER, SP YUNG, YL TI CHLORYL NITRATE - A NOVEL PRODUCT OF THE OCLO+NO3+M RECOMBINATION SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Letter ID TRANSFORM INFRARED-SPECTROSCOPY; CLO; NO3; STRATOSPHERE; LATITUDE; CL2O2 AB The products of the reaction of OClO with NO3 were investigated between 220 and 298 K using a flow reactor and infrared, visible, and ultraviolet analysis. At temperatures below 250 K new infrared and ultraviolet absorption features were observed and assigned to the novel compound chloryl nitrate (O2ClONO2). Additionally, ClO and NO2 were observed as reaction products, indicating the existence of a second reaction channel. O2ClONO2 formation predominates at temperatures below 230 K. The reaction rate constant at 220 K is estimated to be on the order of 10(-14) cm3 molecule-1 s-1 in 1-5 Torr of helium. These observations suggest that O2ClONO2 may exist in the terrestrial stratosphere. C1 CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP FRIEDL, RR (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 22 TC 14 Z9 14 U1 1 U2 8 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 SEP 17 PY 1992 VL 96 IS 19 BP 7490 EP 7493 DI 10.1021/j100198a002 PG 4 WC Chemistry, Physical SC Chemistry GA JN952 UT WOS:A1992JN95200002 PM 11538060 ER PT J AU BHAT, PN FISHMAN, GJ MEEGAN, CA WILSON, RB BROCK, MN PACIESAS, WS AF BHAT, PN FISHMAN, GJ MEEGAN, CA WILSON, RB BROCK, MN PACIESAS, WS TI EVIDENCE FOR SUBMILLISECOND STRUCTURE IN A GAMMA-RAY BURST SO NATURE LA English DT Article AB GAMMA-RAY bursts (GRBs) vary in duration from hundreds of seconds down to several milliseconds. Early studies1 suggested that bursts with durations of < 100 ms form a distinct class, accounting for a few per cent of the total number of detected bursts, and there is some evidence2 for a break in the distribution of GRB durations at approximately 600 ms, perhaps implying separate physical mechanisms for long and short bursts. Recently the estimated number of short GRBs has risen substantially. The shortest burst recorded so far is GRB820405, with duration approximately 12 ms (ref. 3), and the shortest spike within a burst, an unresolved feature with width <5 ms, was in GRB841215 (refs 4-7). GRB790305 had the shortest rise-time, 0.2 ms. We report here that GRB910711, with apparently the shortest duration (approximately 8 ms) yet seen by the Burst and Transient Source Experiment (BATSE), has a time profile that shows significant submillisecond structure. The responses to this burst in the different BATSE detectors, from both direct and Earth-scattered gamma-rays, show that the burst is both narrower and of higher energy than is indicated by a light-curve summed over all detectors. We detected a narrow spike of duration 200-mu-s in the light curve; variations on this timescale have not previously been observed in GRBs, and their explanation should be a stringent test of any GRB theory. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. RP BHAT, PN (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-62,HUNTSVILLE,AL 35812, USA. NR 11 TC 91 Z9 95 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 SEP 17 PY 1992 VL 359 IS 6392 BP 217 EP 218 DI 10.1038/359217a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JN944 UT WOS:A1992JN94400053 ER PT J AU BOUMSELLEK, S CHUTJIAN, A AF BOUMSELLEK, S CHUTJIAN, A TI INCREASED RESPONSE OF THE REVERSAL ELECTRON-ATTACHMENT DETECTOR AND MODELING OF ION SPACE-CHARGE EFFECTS SO ANALYTICAL CHEMISTRY LA English DT Article ID SQUARE-WAVE GENERATOR; HIGH-VOLTAGE; CFCL3; CCL4 AB Design and sensitivity tests of a modified version of the so-called reversal electron attachment detector (READ) are presented. The new version uses a spherical cathode capable of emitting higher electron currents. As in the original READ (which used a planar emitter) electrons are focused into an electrostatic mirror which reverses their trajectories. In the reversal region electrons have essentially zero energy and attach to target molecules to form negative ions. The electron gun lens system has been modified using a field and trajectory code with space charge included. Electron trajectories have been calculated for 1-mA current focused into a reversal region of 3.5-mm diameter. The detection limit of the apparatus is approximately 25 times lower than for the original READ. Non-linearity in the measured signal vs electron current is described by a model in which a spherical ball of ions expands outward with velocity determined by the space-charge force and the initial velocity of ion formation. C1 JET PROP LAB,PASADENA,CA 91109. NR 14 TC 14 Z9 14 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0003-2700 J9 ANAL CHEM JI Anal. Chem. PD SEP 15 PY 1992 VL 64 IS 18 BP 2096 EP 2100 DI 10.1021/ac00042a013 PG 5 WC Chemistry, Analytical SC Chemistry GA JN432 UT WOS:A1992JN43200013 ER PT J AU SHIVAKUMAR, KN NEWMAN, JC AF SHIVAKUMAR, KN NEWMAN, JC TI MIXED-MODE STRESS INTENSITY-FACTORS IN TRANSVERSELY LOADED PLATES SO INTERNATIONAL JOURNAL OF FRACTURE LA English DT Note C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP SHIVAKUMAR, KN (reprint author), N CAROLINA AGR & TECHNOL STATE UNIV,DEPT MECH ENGN,GREENSBORO,NC 27411, USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0376-9429 J9 INT J FRACTURE JI Int. J. Fract. PD SEP 15 PY 1992 VL 57 IS 2 BP R19 EP R25 DI 10.1007/BF00035721 PG 7 WC Materials Science, Multidisciplinary; Mechanics SC Materials Science; Mechanics GA JT117 UT WOS:A1992JT11700007 ER PT J AU SUBRAMANYAM, G KAPOOR, VJ CHOREY, CM BHASIN, KB AF SUBRAMANYAM, G KAPOOR, VJ CHOREY, CM BHASIN, KB TI ELECTRICAL-TRANSPORT PROPERTIES AND MICROWAVE DEVICE PERFORMANCE OF SPUTTERED TLCABACUO SUPERCONDUCTING THIN-FILMS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID CU-O SYSTEM; BULK SUPERCONDUCTIVITY; RESISTANCE; RESONATORS; 120-K AB Tl-Ca-Ba-Cu-O high-temperature superconducting thin films were deposited on lanthanum aluminate substrates, by rf magnetron sputtering and postannealing methods. A reproducible fabrication process with low-resistance metal contacts has been established for high-T(c) and high-J(c) TlCaBaCuO thin films after patterning using standard microelectronic photolithography and wet chemical etching techniques. Low-resistance gold contacts on TlCaBaCuO thin films were obtained by annealing in an oxygen flow of 11/min followed by a slow furnace cooling. Specific contact resistivity was approximately 10(-10) OMEGA-cm2 below 77 K. High transition temperatures as high as 100 K, and current density at zero magnetic field greater than 10(5) A/cm2 are routinely obtained in 0.3-0.5-mu-m TlCaBaCuO thin films. The morphology studies of the films using scanning electron microscopy show the correlation between J(c) and the microstructure of the films. Films with featureless morphology have larger zero-field transport currents. The microwave properties of TlCaBaCuO thin films were investigated by designing, fabricating, and characterizing microstrip ring resonators with a fundamental resonance frequency of 12 GHz on 10-mil-thick lanthanum aluminate (LaAlO3) substrates. Ring resonators with a superconducting ground plane of 0.3-mu-m thickness and a gold ground plane of 1-mu-m thickness were fabricated and characterized in the temperature range of 60-95 K. Typical unloaded quality factors Q for the ring resonators at 12 GHz were above 1500 at 65 K, compared to an unloaded Q of 370 for a gold ring resonator. A surface resistance as low as 1.5 m-OMEGA at 12 GHz and 77 K was obtained in 0.3-mu-m TlCaBaCuO thin films using the ring resonator Q measurements. Typical values of penetration depth at 0 K in the TlCaBaCuO thin films were determined to be between 7000 and 8000 angstrom using the temperature variation of resonance frequency measurements. C1 NASA,LEWIS GRP,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SUBRAMANYAM, G (reprint author), UNIV CINCINNATI,DEPT ELECT & COMP ENGN,MICROWAVE ELECTR LAB,CINCINNATI,OH 45221, USA. NR 23 TC 3 Z9 3 U1 1 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 15 PY 1992 VL 72 IS 6 BP 2396 EP 2403 DI 10.1063/1.351583 PG 8 WC Physics, Applied SC Physics GA JN512 UT WOS:A1992JN51200044 ER PT J AU BOSTON, HG STCLAIR, AK PRATT, JR AF BOSTON, HG STCLAIR, AK PRATT, JR TI POLYIMIDES DERIVED FROM A METHYLENE-BRIDGED DIANHYDRIDE SO JOURNAL OF APPLIED POLYMER SCIENCE LA English DT Article AB A series of linear aromatic polyimide films that are based on a novel methylene-bridged dianhydride, 3,3'-bis(3,4-dicarboxyphenoxy)diphenylmethane dianhydride, have been synthesized and characterized. High molecular weight polyamic acids were prepared by combining this dianhydride with numerous aromatic diamines. The effects of thermal and chemical imidization of the polyamic acids are discussed as they relate to the dielectric constant, optical transparency, and solubility of the resulting polyimide films. The objective of this work was to obtain low dielectric, optically transparent, and soluble polyimides that can be easily processed as coatings or composite matrices for advanced aerospace and electronics applications. C1 NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23665. NR 12 TC 6 Z9 6 U1 0 U2 1 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0021-8995 J9 J APPL POLYM SCI JI J. Appl. Polym. Sci. PD SEP 15 PY 1992 VL 46 IS 2 BP 243 EP 253 DI 10.1002/app.1992.070460205 PG 11 WC Polymer Science SC Polymer Science GA JJ641 UT WOS:A1992JJ64100005 ER PT J AU OCONNOR, DB SCOTT, GW TRAN, K COULTER, DR MISKOWSKI, VM STIEGMAN, AE WNEK, GE AF OCONNOR, DB SCOTT, GW TRAN, K COULTER, DR MISKOWSKI, VM STIEGMAN, AE WNEK, GE TI THE LOW-ENERGY, CHARGE-TRANSFER EXCITED-STATES OF 4-AMINO-4'-NITRODIPHENYL SULFIDE SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID OPTICAL NONLINEARITIES; QUANTUM YIELDS; HYPERPOLARIZABILITIES; FLUORESCENCE; MOLECULES; KINETICS; EMISSION; DYES AB Absorption and emission spectra of 4-amino-4'-nitrodiphenyl sulfide in polar and nonpolar solvents were used to characterize and assign the low-energy excited states of the molecule. Fluorescence-excitation anisotropy spectra, fluorescence and phosphorescence lifetimes, and fluorescence quantum yields were also used to characterize the photophysics of these states. The lowest-energy, fluorescent singlet state was determined to be an intramolecular charge transfer (ICT) state involving transfer of a full electron charge from the amino to the nitro group yielding a dipole moment of approximately 50 D. A low-energy, intense absorption band is assigned as a transition to a different ICT state involving a partial electron charge transfer from sulfur to the nitro group. C1 JET PROP LAB, SPACE MAT SCI & TECHNOL SECT, PASADENA, CA 91109 USA. RENSSELAER POLYTECH INST, DEPT CHEM, TROY, NY 12180 USA. RP OCONNOR, DB (reprint author), UNIV CALIF RIVERSIDE, DEPT CHEM, RIVERSIDE, CA 92521 USA. NR 34 TC 5 Z9 5 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-9606 EI 1089-7690 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 15 PY 1992 VL 97 IS 6 BP 4018 EP 4028 DI 10.1063/1.462941 PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JN146 UT WOS:A1992JN14600016 ER PT J AU ORIENT, OJ MARTUS, KE CHUTJIAN, A MURAD, E AF ORIENT, OJ MARTUS, KE CHUTJIAN, A MURAD, E TI OPTICAL-EMISSION GENERATED BY COLLISIONS OF 5 EV O(P-3) ATOMS WITH SURFACE-ADSORBED HYDRAZINE SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID O(3P) ATOMS; GLOW AB Optical emission has been observed corresponding to vibrational bands in the NH (A 3-PI --> X 3-SIGMA-) electronic transition during collisions of 5 eV, ground-state oxygen O(3P) atoms with MgF2 and Ni surfaces continuously exposed to a beam of hydrazine (N2H4). The NH emission intensity is observed to be about five times greater for MgF2 than for Ni. No dependence on temperature was observed for either surface in the range 240-340 K, implying that the NH-producing intermediate species is tightly bound. The half-lifetime for desorption of hydrazine from each surface was measured. This was found to be 120 min for the MgF2 surface at 240 K, and < 20 min for Ni. After exposure the surface composition was measured using x-ray photoelectron spectroscopy (XPS) on the exposed and unexposed areas of both targets. C1 SPACECRAFT INTERACT BRANCH,PHILLIPS LAB,BEDFORD,MA 01731. RP ORIENT, OJ (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 24 TC 6 Z9 6 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 SEP 15 PY 1992 VL 97 IS 6 BP 4111 EP 4114 DI 10.1063/1.463953 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JN146 UT WOS:A1992JN14600025 ER PT J AU LEE, TJ RICE, JE AF LEE, TJ RICE, JE TI FONO - A DIFFICULT CASE FOR THEORY AND EXPERIMENT SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; NITROSYL HYPOFLUORITE; VIBRATIONAL FREQUENCIES; TRIPLE EXCITATIONS; CONTRACTION; ENERGIES; FOOF AB The equilibrium structures, vibrational spectra, and relative energetics of the FNO2, cis-FONO, and trans-FONO isomers have been investigated using high-levels of ab initio theory. These methods include second-order Moller-Plesset perturbation theory (MP2), singles and doubles coupled-cluster (CCSD) theory, and the CCSD(T) method, which incorporates a perturbational estimate of the effects of connected triple excitations. FNO2 is determined to be 36.9+/-2.5 kcal/mol (0 K) more stable than cis-FONO, which is more stable than trans-FONO by 2.5+/-1.0 kcal/mol (0 K). The molecular structure of cis-FONO is shown to have typical F-O and central O-N single bond distances, indicating that cis-FONO has a structure analogous to HONO. The computed vibrational spectrum of cis-FONO is shown to be consistent with infrared matrix isolation experiments, including isotopic shifts. The experimentally deduced structure of FONO (based on a normal coordinate analysis), however, is shown to be incorrect because one of the vibrational bands included in the normal coordinate analysis is either a combination band or an overtone. C1 IBM CORP, DIV RES, ALMADEN RES CTR, SAN JOSE, CA 95120 USA. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Rice, Julia/K-4928-2012; Lee, Timothy/K-2838-2012 OI Rice, Julia/0000-0001-5059-5127; NR 46 TC 39 Z9 39 U1 1 U2 5 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 15 PY 1992 VL 97 IS 6 BP 4223 EP 4232 DI 10.1063/1.463925 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JN146 UT WOS:A1992JN14600036 ER PT J AU PARKINSON, CL AF PARKINSON, CL TI SPATIAL PATTERNS OF INCREASES AND DECREASES IN THE LENGTH OF THE SEA ICE SEASON IN THE NORTH POLAR-REGION, 1979-1986 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID MULTICHANNEL MICROWAVE RADIOMETER; INTERANNUAL VARIABILITY AB Recently it was reported that sea ice extents in the northern hemisphere showed a very slight but statistically significant decrease over the 8.8-year period of the Nimbus 7 scanning multichannel microwave radiometer (SMMR) data set. In this paper the same SMMR data are used to reveal spatial patterns in increasing and decreasing sea ice coverage. Specifically, the length of the ice season is mapped for each full year of the SMMR data set (1979-1986), and the trends over the 8 years in these ice season lengths are also mapped. These trends show considerable spatial coherence, with a shortening in the sea ice season apparent in much of the eastern hemisphere of the north polar ice cover, particularly in the Sea of Okhotsk, the Barents Sea, and the Kara Sea, and a lengthening of the sea ice season apparent in much of the western hemisphere of the north polar ice cover, particularly in Davis Strait, the Labrador Sea, and the Beaufort Sea. RP PARKINSON, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,CODE 971,GREENBELT,MD 20771, USA. RI Parkinson, Claire/E-1747-2012 OI Parkinson, Claire/0000-0001-6730-4197 NR 20 TC 48 Z9 48 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-OCEANS JI J. Geophys. Res.-Oceans PD SEP 15 PY 1992 VL 97 IS C9 BP 14377 EP 14388 DI 10.1029/92JC01367 PG 12 WC Oceanography SC Oceanography GA JP205 UT WOS:A1992JP20500009 ER PT J AU TURNER, MS WEINBERG, EJ WIDROW, LM AF TURNER, MS WEINBERG, EJ WIDROW, LM TI BUBBLE NUCLEATION IN 1ST-ORDER INFLATION AND OTHER COSMOLOGICAL PHASE-TRANSITIONS SO PHYSICAL REVIEW D LA English DT Article ID EXTENDED INFLATION; FALSE VACUUM; EARLY UNIVERSE; DARK MATTER; PERTURBATIONS; SPECTRUM; FLUCTUATIONS; HORIZON; ORIGIN; DECAY AB We address in some detail the kinematics of bubble nucleation and percolation in first-order cosmological phase transitions, with the primary focus on first-order inflation. We study how a first-order phase transition completes, describe measures of its progress, and compute the distribution of bubble sizes. For example, we find that the typical bubble size in a successful transition is of order 1% to 100% of the Hubble radius, and depends very weakly on the energy scale of the transition. We derive very general conditions that must be satisfied by GAMMA/H-4 to complete the phase transition (GAMMA=bubble nucleation rate per unit volume; H= expansion rate; physically, GAMMA/H-4 corresponds to the volume fraction of space occupied by bubbles nucleated over a Hubble time). In particular, GAMMA/H-4 must exceed 9/4-pi to successfully end inflation. To avoid the deleterious effects of bubbles nucleated early during inflation on primordial nucleosynthesis and on the isotropy and spectrum of the cosmic microwave background radiation, during most of inflation GAMMA/H-4 must be less than order 10(-4)-10(-3). Our constraints imply that in a successful model of first-order inflation the phase transition must complete over a period of at most a few Hubble times and all but preclude individual bubbles from providing an interesting source of density perturbation. We note, though, that it is just possible for Poisson fluctuations in the number of moderately large-size bubbles to lead to interesting isocurvature perturbations, whose spectrum is not scale invariant. Finally, we analyze in detail several recently proposed models of first-order inflation. C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS & ASTRON,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTROPHYS,CHICAGO,IL 60637. FERMI NATL ACCELERATOR LAB,THEORY GRP,BATAVIA,IL 60510. COLUMBIA UNIV,DEPT PHYS,NEW YORK,NY 10027. INST ADV STUDY,SCH OPTOMETRY,PRINCETON,NJ 08540. UNIV TORONTO,CANADIAN INST THEORET ASTROPHYS,TORONTO M5S 1A1,ONTARIO,CANADA. RP TURNER, MS (reprint author), FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 61 TC 81 Z9 81 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1992 VL 46 IS 6 BP 2384 EP 2403 DI 10.1103/PhysRevD.46.2384 PG 20 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA JN598 UT WOS:A1992JN59800016 ER PT J AU BAUSCHLICHER, CW SODUPE, M PARTRIDGE, H LANGHOFF, SR AF BAUSCHLICHER, CW SODUPE, M PARTRIDGE, H LANGHOFF, SR TI THEORETICAL-STUDY OF THE (2)A(2)-(2)B(2) SEPARATION OF THE ALKALI SUPEROXIDES SO CHEMICAL PHYSICS LETTERS LA English DT Article ID POTENTIAL-ENERGY SURFACES; OXYGEN MOLECULES; MATRIX REACTIONS; SPECTRA; ATOMS; ESR AB The computed 2A2-2B2 separations of the alkali superoxides are in good agreement with those deduced from electron-spin resonance spectra. The calculations definitively show that the ground state of CsO2 is 2A2. The larger than expected separation for CsO2, based on the trend from LiO2 to RbO2, is attributed primarily to the differential effects of core relaxation. The CsO2 dissociation energy is computed to be 42.7 kcal/mol, with an uncertainty conservatively estimated as +/- kcal/mol. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 21 TC 8 Z9 8 U1 1 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 SEP 11 PY 1992 VL 197 IS 3 BP 213 EP 216 DI 10.1016/0009-2614(92)85757-2 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JM404 UT WOS:A1992JM40400001 ER PT J AU SMITH, EJ WENZEL, KP PAGE, DE AF SMITH, EJ WENZEL, KP PAGE, DE TI ULYSSES AT JUPITER - AN OVERVIEW OF THE ENCOUNTER SO SCIENCE LA English DT Article ID PLASMA MEASUREMENTS; TORUS AB In February 1992, the Ulysses spacecraft flew through the giant magnetosphere of Jupiter. The primary objective of the encounter was to use the gravity field of Jupiter to redirect the spacecraft to the sun's polar regions, which will now be traversed in 1994 and 1995. However, the Ulysses scientific investigations were well suited to observations of the Jovian magnetosphere, and the encounter has resulted in a major contribution to our understanding of this complex and dynamic plasma environment. Among the more exciting results are (i) possible entry into the polar cap, (ii) the identification of magnetospheric ions originating from Jupiter's ionosphere, lo, and the solar wind, (iii) observation of longitudinal asymmetries in density and discrete wave-emitting regions of the lo plasma torus, (iv) the presence of counter-streaming ions and electrons, field-aligned currents, and energetic electron and radio bursts in the dusk sector on high-latitude magnetic field lines, and (v) the identification of the direction of the magnetic field in the dusk sector, which is indicative of tailward convection. This overview serves as an introduction to the accompanying reports that present the preliminary scientific findings. Aspects of the encounter that are common to all of the investigations, such as spacecraft capabilities, the flight path past Jupiter, and unique aspects of the encounter, are presented herein. C1 EUROPEAN SPACE TECHNOL CTR,POB 299,2200 AG NOORDWIJK,NETHERLANDS. RP SMITH, EJ (reprint author), JET PROP LAB,ESA PROJECT OFF,PASADENA,CA 91109, USA. NR 10 TC 41 Z9 42 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 SEP 11 PY 1992 VL 257 IS 5076 BP 1503 EP 1507 DI 10.1126/science.257.5076.1503 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM570 UT WOS:A1992JM57000022 PM 17776156 ER PT J AU BALOGH, A DOUGHERTY, MK FORSYTH, RJ SOUTHWOOD, DJ SMITH, EJ TSURUTANI, BT MURPHY, N BURTON, ME AF BALOGH, A DOUGHERTY, MK FORSYTH, RJ SOUTHWOOD, DJ SMITH, EJ TSURUTANI, BT MURPHY, N BURTON, ME TI MAGNETIC-FIELD OBSERVATIONS DURING THE ULYSSES FLYBY OF JUPITER SO SCIENCE LA English DT Article ID JOVIAN CURRENT SHEET; MAGNETOSPHERE; MODEL AB The Jovian flyby of the Ulysses spacecraft presented the opportunity to confirm and complement the findings of the four previous missions that investigated the structure and dynamics of the Jovian magnetosphere and magnetic field, as well as to explore for the first time the high-latitude dusk side of the magnetosphere and its boundary regions. In addition to confirming the general structure of the dayside magnetosphere, the Ulysses magnetic field measurements also showed that the importance of the current sheet dynamics extends well into the middle and outer magnetosphere. On the dusk side, the magnetic field is swept back significantly toward the magnetotail. The importance of current systems, both azimuthal and field-aligned, in determining the configuration of the field has been strongly highlighted by the Ulysses data. No significant changes have been found in the internal planetary field; however, the need to modify the external current densities with respect to previous observations on the inbound pass shows that Jovian magnetic and magnetospheric models are highly sensitive to both the intensity and the structure assumed for the current sheet and to any time dependence that may be assigned to these. The observations show that all boundaries and boundary layers in the magnetosphere have a very complex microstructure. Waves and wave-like structures were observed throughout the magnetosphere; these included the longest lasting mirror-mode wave trains observed in space. C1 JET PROP LAB,PASADENA,CA 91109. RP BALOGH, A (reprint author), UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. NR 20 TC 115 Z9 115 U1 0 U2 3 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 11 PY 1992 VL 257 IS 5076 BP 1515 EP 1518 DI 10.1126/science.257.5076.1515 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM570 UT WOS:A1992JM57000026 PM 17776160 ER PT J AU STONE, RG PEDERSEN, BM HARVEY, CC CANU, P CORNILLEAUWEHRLIN, N DESCH, MD DEVILLEDARY, C FAINBERG, J FARRELL, WM GOETZ, K HESS, RA HOANG, S KAISER, ML KELLOGG, PJ LECACHEUX, A LIN, N MACDOWALL, RJ MANNING, R MEETRE, CA MEYERVERNET, N MONCUQUET, M OSHEROVICH, V REINER, MJ TEKLE, A THIESSEN, J ZARKA, P AF STONE, RG PEDERSEN, BM HARVEY, CC CANU, P CORNILLEAUWEHRLIN, N DESCH, MD DEVILLEDARY, C FAINBERG, J FARRELL, WM GOETZ, K HESS, RA HOANG, S KAISER, ML KELLOGG, PJ LECACHEUX, A LIN, N MACDOWALL, RJ MANNING, R MEETRE, CA MEYERVERNET, N MONCUQUET, M OSHEROVICH, V REINER, MJ TEKLE, A THIESSEN, J ZARKA, P TI ULYSSES RADIO AND PLASMA-WAVE OBSERVATIONS IN THE JUPITER ENVIRONMENT SO SCIENCE LA English DT Article ID JOVIAN KILOMETRIC RADIATION; HECTOMETRIC RADIATION; POLARIZATION; FREQUENCY; MAGNETOSPHERE; NOISE; EMISSIONS; TORUS AB The Unified Radio and Plasma Wave (URAP) experiment has produced new observations of the Jupiter environment, owing to the unique capabilities of the instrument and the traversal of high Jovian latitudes. Broad-band continuum radio emission from Jupiter and in situ plasma waves have proved valuable in delineating the magnetospheric boundaries. Simultaneous measurements of electric and magnetic wave fields have yielded new evidence of whistler-mode radiation within the magnetosphere. Observations of auroral-like hiss provided evidence of a Jovian cusp. The source direction and polarization capabilities of URAP have demonstrated that the outer region of the lo plasma torus supported at least five separate radio sources that reoccurred during successive rotations with a measurable corotation lag. Thermal noise measurements of the lo torus densities yielded values in the densest portion that are similar to models suggested on the basis of Voyager observations of 13 years ago. The URAP measurements also suggest complex beaming and polarization characteristics of Jovian radio components. In addition, a new class of kilometer-wavelength striated Jovian bursts has been observed. C1 OBSERV PARIS,F-92195 MEUDON,FRANCE. CTR NATL ETUD TELECOMMUN,CNRS,CTR RECH PHYS ENVIRONNEMENT TERR & PLANETAIRE,F-92131 ISSY MOULINEAUX,FRANCE. UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455. HUGHES STX,LANHAM,MD 20706. RP STONE, RG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI MacDowall, Robert/D-2773-2012; Farrell, William/I-4865-2013 NR 34 TC 89 Z9 89 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 11 PY 1992 VL 257 IS 5076 BP 1524 EP 1530 DI 10.1126/science.257.5076.1524 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM570 UT WOS:A1992JM57000028 PM 17776162 ER PT J AU BIRD, MK ASMAR, SW BRENKLE, JP EDENHOFER, P FUNKE, O PATZOLD, M VOLLAND, H AF BIRD, MK ASMAR, SW BRENKLE, JP EDENHOFER, P FUNKE, O PATZOLD, M VOLLAND, H TI ULYSSES RADIO OCCULTATION OBSERVATIONS OF THE LO PLASMA TORUS DURING THE JUPITER ENCOUNTER SO SCIENCE LA English DT Article ID IO TORUS; VOYAGER; MAGNETOSPHERE; SCIENCE; SYSTEM AB Radio signals from Ulysses were used to probe the lo plasma torus (IPT) shortly after the spacecraft's closest approach to Jupiter. The frequencies of the two downlinks at S-band (2.3 gigahertz) and X-band (8.4 gigahertz) were recorded, differenced, and integrated in order to derive the columnar electron density of the IPT. The measurements agree qualitatively with contemporary models of the IPT based on Voyager data, but significant differences are apparent as well. The overall level of the IPT electron density is approximately the same as the prediction, implying that the amount of gas (or plasma) injected from lo is similar to that observed during the Voyager era. On the other hand, the IPT seems to be less extended out of the centrifugal equator, implying a smaller plasma temperature than predicted. C1 JET PROP LAB,PASADENA,CA 91109. RUHR UNIV BOCHUM,INST HOCHFREQUENZTECH,W-4630 BOCHUM,GERMANY. DFVLR,W-8031 OBERPFAFFENHOFEN,GERMANY. RP BIRD, MK (reprint author), UNIV BONN,INST RADIOASTRON,W-5300 BONN 1,GERMANY. NR 26 TC 25 Z9 25 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 SEP 11 PY 1992 VL 257 IS 5076 BP 1531 EP 1535 DI 10.1126/science.257.5076.1531 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM570 UT WOS:A1992JM57000029 PM 17776163 ER PT J AU GEISS, J GLOECKLER, G BALSIGER, H FISK, LA GALVIN, AB GLIEM, F HAMILTON, DC IPAVICH, FM LIVI, S MALL, U OGILVIE, KW VONSTEIGER, R WILKEN, B AF GEISS, J GLOECKLER, G BALSIGER, H FISK, LA GALVIN, AB GLIEM, F HAMILTON, DC IPAVICH, FM LIVI, S MALL, U OGILVIE, KW VONSTEIGER, R WILKEN, B TI PLASMA COMPOSITION IN JUPITER MAGNETOSPHERE - INITIAL RESULTS FROM THE SOLAR-WIND ION COMPOSITION SPECTROMETER SO SCIENCE LA English DT Article ID SATURN AB The ion composition in the Jovian environment was investigated with the Solar Wind Ion Composition Spectrometer on board Ulysses. A hot tenuous plasma was observed throughout the outer and middle magnetosphere. In some regions two thermally different components were identified. Oxygen and sulfur ions with several different charge states, from the volcanic satellite lo, make the largest contribution to the mass density of the hot plasma, even at high latitude. Solar wind particles were observed in all regions investigated. Ions from Jupiter's ionosphere were abundant in the middle magnetosphere, particularly in the high-latitude region on the dusk side, which was traversed for the first time. C1 UNIV MARYLAND,DEPT PHYS,COLL PK,MD 20742. NASA,OFF SPACE SCI & APPLICAT,WASHINGTON,DC 20546. TECH UNIV BRAUNSCHWEIG,INST DATENVERARBEITENDE ANLAGEN,W-3300 BRAUNSCHWEIG,GERMANY. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP GEISS, J (reprint author), UNIV BERN,INST PHYS,CH-3012 BERN,SWITZERLAND. RI Von Steiger, Rudolf/F-6822-2011; Galvin, Antoinette/A-6114-2013; OI Von Steiger, Rudolf/0000-0002-3350-0023; Hamilton, Douglas/0000-0001-6103-8019 NR 22 TC 46 Z9 46 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 11 PY 1992 VL 257 IS 5076 BP 1535 EP 1539 DI 10.1126/science.257.5076.1535 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM570 UT WOS:A1992JM57000030 PM 17776164 ER PT J AU BAME, SJ BARRACLOUGH, BL FELDMAN, WC GISLER, GR GOSLING, JT MCCOMAS, DJ PHILLIPS, JL THOMSEN, MF GOLDSTEIN, BE NEUGEBAUER, M AF BAME, SJ BARRACLOUGH, BL FELDMAN, WC GISLER, GR GOSLING, JT MCCOMAS, DJ PHILLIPS, JL THOMSEN, MF GOLDSTEIN, BE NEUGEBAUER, M TI JUPITER MAGNETOSPHERE - PLASMA DESCRIPTION FROM THE ULYSSES FLYBY SO SCIENCE LA English DT Article ID EARTHS BOW SHOCK AB Plasma observations at Jupiter show that the outer regions of the Jovian magnetosphere are remarkably similar to those of Earth. Bow-shock precursor electrons and ions were detected in the upstream solar wind, as at Earth. Plasma changes across the bow shock and properties of the magnetosheath electrons were much like those at Earth, indicating that similar processes are operating. A boundary layer populated by a varying mixture of solar wind and magnetospheric plasmas was found inside the magnetopause, again as at Earth. In the middle magnetosphere, large electron density excursions were detected with a 10-hour periodicity as planetary rotation carried the tilted plasma sheet past Ulysses. Deep in the magnetosphere, Ulysses crossed a region, tentatively described as magnetically connected to the Jovian polar cap on one end and to the interplanetary magnetic field on the other. In the inner magnetosphere and lo torus, where corotation plays a dominant role, measurements could not be made because of extreme background rates from penetrating radiation belt particles. C1 JET PROP LAB,PASADENA,CA 91109. RP BAME, SJ (reprint author), LOS ALAMOS NATL LAB,SPACE PLASMA PHYS GRP,MS D438,LOS ALAMOS,NM 87545, USA. NR 12 TC 71 Z9 71 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 11 PY 1992 VL 257 IS 5076 BP 1539 EP 1543 DI 10.1126/science.257.5076.1539 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM570 UT WOS:A1992JM57000031 PM 17776165 ER PT J AU SIMPSON, JA ANGLIN, JD BALOGH, A BURROWS, JR COWLEY, SWH FERRANDO, P HEBER, B HYNDS, RJ KUNOW, H MARSDEN, RG MCKIBBEN, RB MULLERMELLIN, R PAGE, DE RAVIART, A SANDERSON, TR STAINES, K WENZEL, KP WILSON, MD ZHANG, M AF SIMPSON, JA ANGLIN, JD BALOGH, A BURROWS, JR COWLEY, SWH FERRANDO, P HEBER, B HYNDS, RJ KUNOW, H MARSDEN, RG MCKIBBEN, RB MULLERMELLIN, R PAGE, DE RAVIART, A SANDERSON, TR STAINES, K WENZEL, KP WILSON, MD ZHANG, M TI ENERGETIC CHARGED-PARTICLE PHENOMENA IN THE JOVIAN MAGNETOSPHERE - 1ST RESULTS FROM THE ULYSSES COSPIN COLLABORATION SO SCIENCE LA English DT Article ID RADIATION AB The Ulysses spacecraft made the first exploration of the region of Jupiter's magnetosphere at high Jovigraphic latitudes (approximately 37-degrees-south) on the dusk side and reached higher magnetic latitudes (approximately 49-degrees-north) on the day side than any previous mission to Jupiter. The cosmic and solar particle investigations (COSPIN) instrumentation achieved a remarkably well integrated set of observations of energetic charged particles in the energy ranges of approximately 1 to 170 megaelectron volts for electrons and 0.3 to 20 megaelectron volts for protons and heavier nuclei. The new findings include (i) an apparent polar cap region in the northern hemisphere in which energetic charged particles following Jovian magnetic field lines may have direct access to the interplanetary medium, (ii) high-energy electron bursts (rise times less-than-or-equal-to 1 minute and energies extending to > approximately 17 megaelectron volts) on the dusk side that are apparently associated with field-aligned currents and radio burst emissions, (iii) persistence of the global 10-hour relativistic electron "clock" phenomenon throughout Jupiter's magnetosphere, (iv) on the basis of charged-particle measurements, apparent dragging of magnetic field lines at large radii in the dusk sector toward the tail, and (v) consistent outflow of megaelectron volt electrons and large-scale departures from corotation for nucleons. C1 NATL RES COUNCIL CANADA,HERZBERG INST ASTROPHYS,OTTAWA K1A 0R6,ONTARIO,CANADA. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. CENS,SERV ASTROPHYS,F-91191 GIF SUR YVETTE,FRANCE. UNIV KIEL,INST REINE & ANGEW KERNPHYS,W-2300 KIEL 1,GERMANY. EUROPEAN SPACE AGCY,EUROPEAN SPACE RES & TECHNOL CTR,DEPT SPACE SCI,2200 AG NOORDWIJK,NETHERLANDS. JET PROP LAB,EUROPEAN SPACE AGCY,PASADENA,CA 91109. RP SIMPSON, JA (reprint author), UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637, USA. NR 30 TC 65 Z9 65 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 11 PY 1992 VL 257 IS 5076 BP 1543 EP 1550 DI 10.1126/science.257.5076.1543 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM570 UT WOS:A1992JM57000032 PM 17776166 ER PT J AU GRUN, E ZOOK, HA BAGUHL, M FECHTIG, H HANNER, MS KISSEL, J LINDBLAD, BA LINKERT, D LINKERT, G MANN, IB MCDONNELL, JAM MORFILL, GE POLANSKEY, C RIEMANN, R SCHWEHM, G SIDDIQUE, N AF GRUN, E ZOOK, HA BAGUHL, M FECHTIG, H HANNER, MS KISSEL, J LINDBLAD, BA LINKERT, D LINKERT, G MANN, IB MCDONNELL, JAM MORFILL, GE POLANSKEY, C RIEMANN, R SCHWEHM, G SIDDIQUE, N TI ULYSSES DUST MEASUREMENTS NEAR JUPITER SO SCIENCE LA English DT Article ID GOSSAMER RING AB Submicrometer- to micrometer-sized particles were recorded by the Ulysses dust detector within 40 days of the Jupiter flyby. Nine impacts were recorded within 50 Jupiter radii with most of them recorded after closest approach. Three of these impacts are consistent with particles on prograde orbits around Jupiter and the rest are believed to have resulted from gravitationally focused interplanetary dust. From the ratio of the impact rate before the Jupiter flyby to the impact rate after the Jupiter flyby it is concluded that interplanetary dust particles at the distance of Jupiter move on mostly retrograde orbits. On 10 March 1992, Ulysses passed through an intense dust stream. The dust detector recorded 126 impacts within 26 hours. The stream particles were moving on highly inclined and apparently hyperbolic orbits with perihelion distances of >5 astronomical units. Interplanetary dust is lost rather quickly from the solar system through collisions and other mechanisms and must be almost continuously replenished to maintain observed abundances. Dust flux measurements, therefore, give evidence of the recent rates of production from sources such as comets, asteroids, and moons, as well as the possible presence of interstellar grains. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. JET PROP LAB,PASADENA,CA 91109. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. UNIV KENT,CANTERBURY CT2 7NR,ENGLAND. MAX PLANCK INST EXTRATERRESTR PHYS,W-8046 GARCHING,GERMANY. EUROPEAN SPACE AGCY,EUROPEAN SPACE TECHNOL CTR,2200 AG NOORDWIJK,NETHERLANDS. RP GRUN, E (reprint author), MAX PLANCK INST NUCL PHYS,W-6900 HEIDELBERG 1,GERMANY. NR 17 TC 38 Z9 38 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 11 PY 1992 VL 257 IS 5076 BP 1550 EP 1552 DI 10.1126/science.11538054 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM570 UT WOS:A1992JM57000033 PM 11538054 ER PT J AU LIU, DTH CHENG, LJ AF LIU, DTH CHENG, LJ TI REAL-TIME VANDERLUGT OPTICAL CORRELATOR THAT USES PHOTOREFRACTIVE GAAS SO APPLIED OPTICS LA English DT Article ID BI12SIO20 CRYSTALS AB A real-time GaAs and liquid-crystal television- (LCTV-) based optical correlator is demonstrated. The speed of this correlator (video rate) is limited by the LCTV's; with faster spatial light modulators, the potential speed of a GaAs-based correlator may be 1000 frames/s or higher. Comparisons are made between VanderLugt and joint transform configurations and between degenerate and nondegenerate four-wave mixings. The edge-enhancement effect and the Bragg diffraction effect are also discussed. RP LIU, DTH (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 14 TC 14 Z9 14 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 SEP 10 PY 1992 VL 31 IS 26 BP 5675 EP 5680 PG 6 WC Optics SC Optics GA JN544 UT WOS:A1992JN54400028 PM 20733752 ER PT J AU JUNG, YD AF JUNG, YD TI A SIMPLE CORRECTION FOR THE BORN APPROXIMATION FOR ELECTRON-IMPACT EXCITATION OF HYDROGENIC IONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES AB We develop an analytic procedure for obtaining the electron impact excitation cross sections for hydrogenic ions. A simple modification of the Born approximation, in order to include Coulomb focusing of the continuum wave functions, produces the correct energy dependence of the cross section near excitation threshold. We use this procedure to compute the 1 s --> 2s and 1 s --> 2p excitation cross sections for hydrogenic ions (Z --> infinity), and compare these modified-Born cross sections with numerical Colomb-Born calculations. The modified-Born cross sections agree well with the Coulomb-Born cross sections and thus provide a reliable generalized analytic expression for electron impact excitation of hydrogenic ions. By treating effective charges, the results in this work can be extended to nonhydrogenic target systems. RP JUNG, YD (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-65,HUNTSVILLE,AL 35812, USA. NR 13 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1992 VL 396 IS 2 BP 725 EP 729 DI 10.1086/171755 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JL152 UT WOS:A1992JL15200030 ER PT J AU CHENG, KP BRUHWEILER, FC KONDO, Y GRADY, CA AF CHENG, KP BRUHWEILER, FC KONDO, Y GRADY, CA TI NEWLY IDENTIFIED MAIN-SEQUENCE A STARS WITH CIRCUMSTELLAR DUST SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; INFRARED, STARS; STARS, EARLY-TYPE ID PROTO-PLANETARY SYSTEM; BETA-PICTORIS; MATTER; DISK AB We have searched for stars with circumstellar (CS) dust using data from the Infrared Astronomical Satellite (IRAS) in two stellar samples: (I) all of the 62 A stars in Woolley's Catalogue of Stars within 25 Parsecs of the Sun (1970) and (II) 100 A stars in the Bright Star Catalogue with 4 less-than-or-equal-to m(V) less-than-or-equal-to 5 and nu sin i greater-than-or-equal-to 100 km s-1. Our sample I represents an almost volume-limited sample, of which 29 stars have detections in three (12, 25, and 60-mu-m) or more IRAS bandpasses using the Faint Source Survey (FSS) data base and the new ADDSCAN/SCANPI software. We find 11 nearby A stars having [12] - [25] and [25] - [60] colors consistent with circumstellar dust. If this sample is representative of the Galaxy as a whole, more than 18% (11/62) of all A stars would have circumstellar dust. Among these 11 proto-planetary system candidates, five, namely, HD 29573 (A2 IV), HD 78045 (A2-A3 IV), HD 84121 (A3 IV), HD 159492 (A5 IV-V), and HD 193571 (A0 V) are reported for the first time. The analysis of sample 11 demonstrates that the use of the FSS data base indeed increases the likelihood of identifying A stars with CS dust fainter than m(V) = 4. As a result, we find three more new dusty systems, HD 110411 (A0 V), HD 143894 (A0 IV), and HD 125473 (A3 V) in this sample. All eight of our newly identified dusty systems from both samples have Vega-like colors, which suggests that the IR emission of these systems is from warm dust similar to that seen for Vega (A0 V). So far, beta-Pictoris (A5 IV-V) is the only star within 25 pc of the Sun that displays IR colors indicative of both warm and cool dust. One interpretation is that the absence of cool dust in the vast majority of the systems implies that the dust disks of these stars are much less extended than that seen around beta-Pictoris. This is also consistent with the present negative results from attempts to image dust disks around other nearby stars directly. C1 CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064. RP CHENG, KP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 21 TC 47 Z9 47 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 SEP 10 PY 1992 VL 396 IS 2 BP L83 EP L86 DI 10.1086/186522 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JL153 UT WOS:A1992JL15300007 ER PT J AU MANDZHAVIDZE, N RAMATY, R AF MANDZHAVIDZE, N RAMATY, R TI GAMMA-RAYS FROM PION DECAY - EVIDENCE FOR LONG-TERM TRAPPING OF PARTICLES IN SOLAR-FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAY, OBSERVATIONS; SUN, FLARES; SUN, PARTICLE EMISSION AB We analyze the energy spectrum and time dependence of the 50 MeV to 2 GeV gamma rays observe from the 1991 June 11 solar flare. We show that the emission detected at the late phase of this flare with EGRET on the Compton Gamma-Ray Observatory can be explained by a model in which the bulk of the particles were accelerated during the impulsive phase and subsequently trapped in coronal magnetic loops. We fit the observed spectrum with a combination of pion decay radiation and primary electron bremsstrahlung. We compare the 1991 June 11 data with data for the 1982 June 3 and 1991 June 15 flares from which pion decay emission was also observed. The fact that the fluxes from these three flares are ordered in time in accordance with the predicted time dependence of emission produced by trapped particles provides support for the model. C1 UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS,GREENBELT,MD 20771. NR 18 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 SEP 10 PY 1992 VL 396 IS 2 BP L111 EP L114 DI 10.1086/186529 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JL153 UT WOS:A1992JL15300014 ER PT J AU HOLMAN, R HSU, SDH KOLB, EW WATKINS, R WIDROW, LM AF HOLMAN, R HSU, SDH KOLB, EW WATKINS, R WIDROW, LM TI COSMOLOGICAL TEXTURE IS SENSITIVE TO PLANCK-SCALE PHYSICS SO PHYSICAL REVIEW LETTERS LA English DT Article ID GLOBAL TEXTURE; CONSTANT; ORIGIN AB Nambu-Goldstone modes are sensitive to the effects of physics at energies comparable to the scale of spontaneous symmetry breaking. We show that as a consequence of this the global texture proposal for structure formation requires rather severe assumptions about the nature of physics at the Planck scale. C1 CARNEGIE MELLON UNIV,DEPT PHYS,PITTSBURGH,PA 15213. HARVARD UNIV,LYMAN LAB PHYS,CAMBRIDGE,MA 02138. NASA,FERMILAB ASTROPHYS,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV TORONTO,CANADIAN INST THEORET ASTROPHYS,TORONTO M5S 1A1,ONTARIO,CANADA. RP HOLMAN, R (reprint author), UNIV CALIF SANTA BARBARA,INST THEORET PHYS,SANTA BARBARA,CA 93106, USA. NR 26 TC 33 Z9 33 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD SEP 7 PY 1992 VL 69 IS 10 BP 1489 EP 1492 DI 10.1103/PhysRevLett.69.1489 PG 4 WC Physics, Multidisciplinary SC Physics GA JL610 UT WOS:A1992JL61000004 ER PT J AU ESCOUBET, CP SMITH, MF FUNG, SF ANDERSON, PC HOFFMAN, RA BASINSKA, EM BOSQUED, JM AF ESCOUBET, CP SMITH, MF FUNG, SF ANDERSON, PC HOFFMAN, RA BASINSKA, EM BOSQUED, JM TI STAIRCASE ION SIGNATURE IN THE POLAR CUSP - A CASE-STUDY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FLUX-TRANSFER EVENTS; PLASMA AB On 15 October 1981 Dynamics Explorer 2 crossed the polar cusp at 1015 MLT and observed three distinct ion populations as it was moving poleward. These three populations had peak-flux energy around 2.7 keV, 850 eV and 360 eV. At the time of observation, the IMF was southward. The first step coincided with a rotation of the flow from westward to poleward and then eastward. The second and third steps showed a flow directed principally poleward. Furthermore, the magnetic and electric perturbations in the first step are well fitted by an elongated flux tube footprint model. These results suggest that three consecutive Flux Transfer Events (FTEs) have injected solar wind plasma into the ionosphere forming the polar cusp. The individual FTE signatures can only be identified by the jumps in the precipitation pattern. The newest reconnected FTE footprint was crossed near the edge of the event while the two oldest ones were crossed around the event center. The small latitudinal size of these FTE footprints (approximately 40 km) and their short recurrence rate (3, 6 min) is consistent with an intermittent reconnection taking place at the subsolar point on a short time scale. C1 CNRS,CTR ETUD SPATIALE RAYONNEMENTS,F-31029 TOULOUSE,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. BOSTON UNIV,CTR SPACE PHYS,BOSTON,MA 02215. RI Fung, Shing/F-5647-2012 NR 17 TC 71 Z9 71 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 SEP 4 PY 1992 VL 19 IS 17 BP 1735 EP 1738 DI 10.1029/92GL01806 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JP126 UT WOS:A1992JP12600004 ER PT J AU JENSEN, EJ TOON, OB AF JENSEN, EJ TOON, OB TI THE POTENTIAL EFFECTS OF VOLCANIC AEROSOLS ON CIRRUS CLOUD MICROPHYSICS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EL-CHICHON; LIDAR AB The potential impact of volcanic aerosols on nucleation of ice crystals in upper tropospheric cirrus clouds is examined from a microphysical perspective. The sulfuric acid aerosols which form in the stratosphere are presumably transported into the troposphere by sedimentation and tropopause folding. The tropospheric volcanic aerosol size distribution is estimated from 10-mu-m lidar backscatter measurements [Post, 1986] and in situ measurements [Pueschel et al., 1992b]. Microphysical simulations suggest that at temperatures below about -50-degrees-C the concentration of ice crystals which nucleate may be as much as a factor of 5 larger when volcanic aerosols are present. Our simulations suggest that the presence of volcanic aerosols may increases the net radiative forcing (surface warming) of certain types of cirrus near the tropopause by as much as 8 W/m2. Further observations are required to determine whether these effects actually occur, and their global impact. RP JENSEN, EJ (reprint author), NASA,AMES RES CTR,MAIL STOP 245-4,MOFFETT FIELD,CA 94035, USA. NR 21 TC 53 Z9 53 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 SEP 4 PY 1992 VL 19 IS 17 BP 1759 EP 1762 DI 10.1029/92GL01936 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JP126 UT WOS:A1992JP12600010 ER PT J AU MOHLER, O ARNOLD, F AF MOHLER, O ARNOLD, F TI GASEOUS SULFURIC-ACID AND SULFUR-DIOXIDE MEASUREMENTS IN THE ARCTIC TROPOSPHERE AND LOWER STRATOSPHERE - IMPLICATIONS FOR HYDROXYL RADICAL ABUNDANCES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID IONIZATION MASS-SPECTROMETRY; AEROSOL FORMATION; BALLOON; IONS AB Measurements of gaseous sulfuric acid and sulfur dioxide were made in the winter arctic troposphere and lower stratosphere, using aircraft-borne mass spectrometers. The measurements, covering altitudes between 3.5 and 11.4 km, took place on 14 and 18 February, 1987 in Northern Scandinavia. The abundance of H2SO4 Wu around 0.01 to 0.06 pptv (parts per trillion by volume) and the measured SO2 volume mixing ratios are around 50 to 400 pptv in the troposphere and decrease steeply above the tropopause to about 10 pptv. This decrease above the tropopause is in contrast to previous measurements showing constant or even increasing SO2 mixing ratios. The combined H2SO4 and SO2 Measurements offer an interesting opportunity to infer hydroxyl radical concentrations. Inferred OH concentrations are around 0.1-1.0 x 10(5) cm-3 being roughly consistent with model predictions for winter time high latitudes. RP MOHLER, O (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Mohler, Ottmar/J-9426-2012 NR 23 TC 52 Z9 52 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 4 PY 1992 VL 19 IS 17 BP 1763 EP 1766 DI 10.1029/92GL01807 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JP126 UT WOS:A1992JP12600011 ER PT J AU RAMPINO, MR SELF, S AF RAMPINO, MR SELF, S TI VOLCANIC WINTER AND ACCELERATED GLACIATION FOLLOWING THE TOBA SUPER-ERUPTION SO NATURE LA English DT Article ID VOSTOK ICE-CORE; NORTHERN HEMISPHERE GLACIATION; GENERAL-CIRCULATION MODEL; SHEET GROWTH; CLIMATE; RECORD; RECONSTRUCTION; TEMPERATURE; DYNAMICS; AEROSOLS AB THE eruption of Toba in Sumatra 73,500 years ago was the largest known explosive volcanic event in the late Quaternary1. It could have lofted about 10(15) g each of fine ash and sulphur gases to heights of 27-37 km, creating dense stratospheric dust and aerosol clouds. Here we present model calculations that investigate the possible climatic effects of the volcanic cloud. The increase in atmospheric opacity might have produced a 'volcanic winter'2-a brief, pronounced regional and perhaps hemispheric cooling caused by the volcanic dust-followed by a few years with maximum estimated annual hemispheric surface-temperature decreases of 3-5-degrees-C. The eruption occurred during the stage 5a-4 transition of the oxygen isotope record, a time of rapid ice growth and falling sea level3. We suggest that the Toba eruption may have greatly accelerated the shift to glacial conditions that was already underway, by inducing perennial snow cover and increased sea-ice extent at sensitive northern latitudes. As the onset of climate change may have helped to trigger the eruption itself4, we propose that the Toba event may exemplify a more general climate-volcano feedback mechanism. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. UNIV HAWAII MANOA,SCH OCEAN & EARTH SCI & TECHNOL,DEPT GEOL & GEOPHYS,HONOLULU,HI 96822. RP RAMPINO, MR (reprint author), NYU,DEPT APPL SCI,EARTH SYST GRP,NEW YORK,NY 10003, USA. NR 48 TC 219 Z9 229 U1 39 U2 126 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD SEP 3 PY 1992 VL 359 IS 6390 BP 50 EP 52 DI 10.1038/359050a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JL662 UT WOS:A1992JL66200049 ER PT J AU DOODY, D AF DOODY, D TI MAPPING MAGELLAN PROSPECTS SO AEROSPACE AMERICA LA English DT Article RP DOODY, D (reprint author), JET PROP LAB,PASADENA,CA 91109, 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 SEP PY 1992 VL 30 IS 9 BP 12 EP 14 PG 3 WC Engineering, Aerospace SC Engineering GA JL645 UT WOS:A1992JL64500004 ER PT J AU KEHOE, MW RICKETTS, RH AF KEHOE, MW RICKETTS, RH TI GETTING UP TO SPEED IN HYPERSONIC STRUCTURES SO AEROSPACE AMERICA LA English DT Article RP KEHOE, MW (reprint author), NASA,AMES RES CTR,STRUCT DYNAM SECT,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD SEP PY 1992 VL 30 IS 9 BP 18 EP & PG 0 WC Engineering, Aerospace SC Engineering GA JL645 UT WOS:A1992JL64500006 ER PT J AU KVATERNIK, RG AF KVATERNIK, RG TI DAMVIBS LOOKS AT ROTORCRAFT VIBRATION SO AEROSPACE AMERICA LA English DT Article RP KVATERNIK, RG (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 SEP PY 1992 VL 30 IS 9 BP 22 EP 24 PG 3 WC Engineering, Aerospace SC Engineering GA JL645 UT WOS:A1992JL64500007 ER PT J AU NEWSOM, JR SLIMAK, LK AF NEWSOM, JR SLIMAK, LK TI INTERACTING FOR BETTER PERFORMANCE SO AEROSPACE AMERICA LA English DT Article RP NEWSOM, JR (reprint author), NASA,LANGLEY RES CTR,CONTROLS STRUCT INTERACT OFF,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 SEP PY 1992 VL 30 IS 9 BP 30 EP 32 PG 3 WC Engineering, Aerospace SC Engineering GA JL645 UT WOS:A1992JL64500009 ER PT J AU WADA, BK TRACY, J AF WADA, BK TRACY, J TI STRUCTURES THAT ADAPT TO SPACE SO AEROSPACE AMERICA LA English DT Article RP WADA, BK (reprint author), JET PROP LAB,PASADENA,CA 91109, 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 SEP PY 1992 VL 30 IS 9 BP 38 EP 41 PG 4 WC Engineering, Aerospace SC Engineering GA JL645 UT WOS:A1992JL64500011 ER PT J AU GOLDIN, DS AF GOLDIN, DS TI ACCOUNTABILITY AND QUALITY IN NASA PROCUREMENT SO AEROSPACE AMERICA LA English DT Editorial Material RP GOLDIN, DS (reprint author), NASA,WASHINGTON,DC 20546, 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 SEP PY 1992 VL 30 IS 9 BP B7 EP & PG 0 WC Engineering, Aerospace SC Engineering GA JL645 UT WOS:A1992JL64500017 ER PT J AU DRUMMOND, M AF DRUMMOND, M TI PRACTICAL APPROACHES TO SCHEDULING AND PLANNING SO AI MAGAZINE LA English DT Article RP DRUMMOND, M (reprint author), NASA,AMES RES CTR,STERLING SOFTWARE,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 SN 0738-4602 J9 AI MAG JI AI Mag. PD FAL PY 1992 VL 13 IS 3 BP 26 EP 26 PG 1 WC Computer Science, Artificial Intelligence SC Computer Science GA JP640 UT WOS:A1992JP64000008 ER PT J AU LOWRY, MR AF LOWRY, MR TI SOFTWARE ENGINEERING IN THE 21ST-CENTURY SO AI MAGAZINE LA English DT Article ID EXPLANATION; SYSTEMS; DESIGN AB There is substantial evidence that Al technology can meet the requirements of the large potential market that will exist for knowledge-based software engineering at the turn of the century. In this article, which forms the conclusion to the AAAI Press book Automating Software Design, edited by Michael Lowry and Robert McCartney, Michael Lowry discusses the future of software engineering, and how knowledge-based software engineering (KBSE) progress will lead to system development environments. Specifically, Lowry examines how KBSE techniques promote additive programming methods and how they can be developed and introduced in an evolutionary way. RP LOWRY, MR (reprint author), NASA,AMES RES CTR,ARTIFICIAL INTELLIGENCE RES BRANCH,MOFFETT FIELD,CA 94035, USA. NR 40 TC 5 Z9 5 U1 0 U2 1 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 SN 0738-4602 J9 AI MAG JI AI Mag. PD FAL PY 1992 VL 13 IS 3 BP 71 EP 87 PG 17 WC Computer Science, Artificial Intelligence SC Computer Science GA JP640 UT WOS:A1992JP64000016 ER PT J AU AGARWAL, NK MADDALON, DV MANGALAM, SM COLLIER, FS AF AGARWAL, NK MADDALON, DV MANGALAM, SM COLLIER, FS TI CROSS-FLOW VORTEX AND TRANSITION MEASUREMENTS BY USE OF MULTIELEMENT HOT FILMS SO AIAA JOURNAL LA English DT Article AB An experiment on a 45-deg swept wing was conducted to study three-dimensional boundary-layer characteristics using surface-mounted, microthin, multielement hot-film sensors. A large hot-film gauge was fabricated that combined three arrays of 64 crossflow sensors each and a single array of 32 transition sensors. Two such gauges were mounted along the model chord. Crossflow vortex structure and boundary-layer transition were measured from the simultaneously acquired signals of the hot films. Stationary and nonstationary crossflow disturbances were measured from hot-film sensor arrays. Spanwise variation of the root-mean-square hot-film signal show a local minima and maxims. The distance between two minima corresponds to the stationary crossflow vortex wavelength and agrees with naphthalene flow-visualization results. The chordwise and span-wise variation of amplified traveling (nonstationary) crossflow disturbance characteristics were measured as Reynolds number was varied. The frequency of the most amplified crossflow disturbances agrees with linear stability theory. C1 NASA,LANGLEY RES CTR,LAMINAR FLOW CONTROL PROJECT OFF,HAMPTON,VA 23665. RP AGARWAL, NK (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 27 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 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1992 VL 30 IS 9 BP 2212 EP 2218 DI 10.2514/3.11207 PG 7 WC Engineering, Aerospace SC Engineering GA JM022 UT WOS:A1992JM02200007 ER PT J AU DEGANI, D LEVY, Y AF DEGANI, D LEVY, Y TI ASYMMETRIC TURBULENT VORTICAL FLOWS OVER SLENDER BODIES SO AIAA JOURNAL LA English DT Article ID NUMERICAL-SIMULATION; VORTEX ASYMMETRY; OGIVE-CYLINDER; SEPARATION AB Time-accurate numerical solutions have been obtained for equations modeling turbulent subsonic flows over a slender ogive-cylinder body of revolution in the high-angle-of-attack regime where a large asymmetry in the mean flow has been observed experimentally. A modified algebraic eddy-viscosity turbulence model was utilized to correctly compute the effects of the asymmetric vortices on the underlying viscous layers. To reproduce any one of the experimentally observed asymmetric flowfields, it was found necessary to add a small geometrical disturbance near the body apex. By determining an appropriate size of the disturbance, it was possible to obtain excellent agreement between numerical results and experimental data for angles of attack of 30 and 40 deg, Reynolds numbers of Re(D) = 3.0 x 10(6) and Re(D) = 4.0 x 10(6), and several roll angles. When the disturbance was removed, the calculated flowfield returned to its original symmetric shape. These results are similar in behavior to solutions obtained previously for laminar flows. As in the laminar case, results suggest that the origin of the asymmetry is a convective-type instability of an originally symmetric flow. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP DEGANI, D (reprint author), TECHNION ISRAEL INST TECHNOL,FAC MECH ENGN,IL-32000 HAIFA,ISRAEL. NR 26 TC 23 Z9 24 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 SEP PY 1992 VL 30 IS 9 BP 2267 EP 2273 DI 10.2514/3.11214 PG 7 WC Engineering, Aerospace SC Engineering GA JM022 UT WOS:A1992JM02200014 ER PT J AU NOOR, AK BURTON, S AF NOOR, AK BURTON, S TI ACCURACY OF CRITICAL-TEMPERATURE SENSITIVITY COEFFICIENTS PREDICTED BY MULTILAYERED COMPOSITE PLATE THEORIES SO AIAA JOURNAL LA English DT Article ID FREE-VIBRATION ANALYSES; CORRECTOR PROCEDURES; TRANSVERSE-SHEAR; STRESS AB An assessment is made of the accuracy of the critical-temperature sensitivity coefficients of multilayered plates predicted by different modeling approaches, based on two-dimensional shear-deformation theories. The sensitivity coefficients considered measure the sensitivity of the critical temperatures to variations in different lamination and material parameters of the plate. The standard of comparison is taken to be the sensitivity coefficients obtained by the three-dimensional theory of thermoelasticity. Numerical studies are presented showing the effects of variation in the geometric and lamination parameters of the plate on the accuracy of both the sensitivity coefficients and the critical temperatures predicted by the different modeling approaches. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NR 19 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0001-1452 EI 1533-385X J9 AIAA J JI AIAA J. PD SEP PY 1992 VL 30 IS 9 BP 2283 EP 2290 DI 10.2514/3.11216 PG 8 WC Engineering, Aerospace SC Engineering GA JM022 UT WOS:A1992JM02200016 ER PT J AU HOU, GJW KENNY, SP AF HOU, GJW KENNY, SP TI EIGENVALUE AND EIGENVECTOR APPROXIMATE ANALYSIS FOR REPEATED EIGENVALUE PROBLEMS SO AIAA JOURNAL LA English DT Article ID DERIVATIVES AB Repeated eigenvalue problems occur in engineering design and analysis practices. The discontinuous nature of these problems has recently attracted significant interest in sensitivity analysis. The objectives of this paper are to present a method for eigenvalue and eigenvector approximate analysis in the presence of repeated eigenvalues and to present an alternate method for the eigenvector sensitivity equations. The method developed for approximate analysis involves a reparamaterization of the multivariable structural eigenvalue problems in terms of a single positive-valued parameter. The resulting equations yield first-order approximations of changes in both the eigenvalues and eigenvectors associated with the repeated eigenvalue problem. Examples are given to demonstrate the application of such equations for sensitivity and approximate analysis. C1 NASA,LANGLEY RES CTR,SPACECRAFT CONTROLS BRANCH,HAMPTON,VA 23665. RP HOU, GJW (reprint author), OLD DOMINION UNIV,DEPT MECH ENGN & MECH,NORFOLK,VA 23508, USA. NR 8 TC 10 Z9 12 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 SEP PY 1992 VL 30 IS 9 BP 2317 EP 2324 DI 10.2514/3.11220 PG 8 WC Engineering, Aerospace SC Engineering GA JM022 UT WOS:A1992JM02200020 ER PT J AU FARASSAT, F DUNN, MH SPENCE, PL AF FARASSAT, F DUNN, MH SPENCE, PL TI ADVANCED PROPELLER NOISE PREDICTION IN THE TIME DOMAIN SO AIAA JOURNAL LA English DT Note ID FREQUENCY C1 LOCKHEED ENGN & SCI CO,DEPT ACOUST & DYNAM,HAMPTON,VA 23666. RP FARASSAT, F (reprint author), NASA,LANGLEY RES CTR,APPL ACOUST BRANCH,HAMPTON,VA 23665, USA. NR 13 TC 8 Z9 10 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 SEP PY 1992 VL 30 IS 9 BP 2337 EP 2340 DI 10.2514/3.11224 PG 4 WC Engineering, Aerospace SC Engineering GA JM022 UT WOS:A1992JM02200024 ER PT J AU CASNER, SM AF CASNER, SM TI HUMAN ERROR - REASON,J SO APPLIED COGNITIVE PSYCHOLOGY LA English DT Book Review RP CASNER, SM (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0888-4080 J9 APPL COGNITIVE PSYCH JI Appl. Cogn. Psychol. PD SEP-OCT PY 1992 VL 6 IS 5 BP 456 EP 457 DI 10.1002/acp.2350060510 PG 2 WC Psychology, Experimental SC Psychology GA JT681 UT WOS:A1992JT68100009 ER PT J AU HERRERO, FA AF HERRERO, FA TI LIGHT-TRAP DESIGN USING MULTIPLE REFLECTIONS AND SOLID-ANGLE ATTENUATION - APPLICATION TO A SPACEBORNE ELECTRON SPECTROMETER SO APPLIED OPTICS LA English DT Article AB The design and performance of a new light trap for a spaceborne electron spectrometer are described. The light trap has a measured photon-rejection ratio of 2 X 10(-11), allowing only one in 5 X 10(10) incident photons to reach the sensitive area of the instrument. This rejection is more than sufficient because the ambient ultraviolet in Earth orbit requires a rejection no better than 10(-8) to maintain the photon interference to less than 10 count/s. The light trap uses triple reflections to keep most of the light passing through the entrance slit away from the sensitive area of the spectrometer. However, because of electron-optic requirements, the edge of one of the metallic electrodes falls within the field of view of the sensitive area, allowing double-reflection photon paths to reach the sensitive area. Assuming diffuse reflectance r, the author shows that the photon rejection can be written as epsilon = G2r2 + G3r3 with G3 approximately 10 times larger than G2. Both coefficients depend only on the internal surface geometry; G2 represents the electrode edge reflections (second-order) and G3 represents the triple-reflection (third-order) paths. As shown by the analysis and measurements taken at two different values of r, the rejection is controlled by triple reflections if r > 0.08. It is shown that the average reflectance of all the internal surfaces must be less than 0.006, which is consistent with the data on the black coating applied to all surfaces. The analysis makes it possible to compare the photon contributions of each of the internal reflecting areas and to estimate the effective scattering width of the metallic electrode edge. RP HERRERO, FA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 14 TC 8 Z9 8 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 SEP 1 PY 1992 VL 31 IS 25 BP 5331 EP 5340 PG 10 WC Optics SC Optics GA JL270 UT WOS:A1992JL27000032 PM 20733715 ER PT J AU SINGH, JJ SHEN, CP SPRINKLE, DR AF SINGH, JJ SHEN, CP SPRINKLE, DR TI GAMMA-RAY SLUSH HYDROGEN MONITOR SO APPLIED RADIATION AND ISOTOPES LA English DT Article AB Mass attenuation coefficients for Cd-109 radiation have been measured in single phases and mixtures of phases of five chemical compounds. As expected, the mass attenuation coefficients are independent of the phases of the test chemicals. As a result of this study, it is recommended that a slush hydrogen monitoring system based on low energy gamma ray attenuation be developed for use on board the National Aerospace Plane. C1 OLD DOMINION UNIV,RES FDN,NORFOLK,VA 23508. RP SINGH, JJ (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 4 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 0969-8043 J9 APPL RADIAT ISOTOPES JI Appl. Radiat. Isot. PD SEP PY 1992 VL 43 IS 9 BP 1143 EP 1146 PG 4 WC Chemistry, Inorganic & Nuclear; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Chemistry; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA JH863 UT WOS:A1992JH86300014 ER PT J AU MEEHAN, R SMITH, M REED, R SAMS, C AF MEEHAN, R SMITH, M REED, R SAMS, C TI POTENTIAL NEUROENDOCRINE MECHANISMS OF T-CELL DYSFUNCTION IN SLE PATIENTS SO ARTHRITIS AND RHEUMATISM LA English DT Meeting Abstract C1 UNIV COLORADO,HLTH SCI CTR,DENVER,CO 80262. USAF ACAD,COLORADO SPRINGS,CO 80840. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0004-3591 J9 ARTHRITIS RHEUM JI Arthritis Rheum. PD SEP PY 1992 VL 35 IS 9 SU S BP S288 EP S288 PG 1 WC Rheumatology SC Rheumatology GA JR158 UT WOS:A1992JR15801274 ER PT J AU ASHBY, M HOUCK, JR HACKING, PB AF ASHBY, M HOUCK, JR HACKING, PB TI DEEP INFRARED GALAXIES SO ASTRONOMICAL JOURNAL LA English DT Article ID CLASSIFICATION; SAMPLE AB We present high signal-to-noise ratio optical spectra of 17 infrared-bright emission-line galaxies near the north ecliptic pole. Reddening-corrected line ratios [O III] lambda-5007/H-beta, [N II] lambda-6583/H-alpha, [S II] (lambda-6716 + lambda-6731)/H-alpha, and [O I] lambda-6300/H-alpha are used to discriminate between candidate energy generation mechanisms in each galaxy. These criteria have frequently been applied to optically selected samples of galaxies in the past, but this is the first time they have been applied to a set of faint flux-limited infrared-selected objects. The analysis indicates the sample contains seven starburst galaxies and three active galactic nuclei (AGNs). However, seven galaxies in our sample elude the classification scheme based on these line ratios. We conclude that a two-component (starburst plus AGN) model for energy generation in galaxies is inadequate for infrared galaxies. C1 JET PROP LAB,PASADENA,CA 91109. RP ASHBY, M (reprint author), CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853, USA. NR 21 TC 17 Z9 17 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 SEP PY 1992 VL 104 IS 3 BP 980 EP 989 DI 10.1086/116291 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JL466 UT WOS:A1992JL46600006 ER PT J AU BABEL, J LANZ, T AF BABEL, J LANZ, T TI STRATIFICATION OF CHEMICAL-ELEMENTS IN THE ATMOSPHERE OF THE AP STAR 53-CAMELOPARDALIS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STELLAR ATMOSPHERES; PECULIAR A-STARS; DIFFUSION PROCESSES; ABUNDANCES; MAGNETIC FIELD; MASS LOSS ID MODEL ATMOSPHERES; DIFFUSION; ABUNDANCE; PECULIAR AB One of the most direct test of element separation in the atmosphere of Ap stars is the detection of the stratification of chemical elements. This test, although fundamental, is difficult and several previous investigations failed to reach any firm conclusion. The cool Ap star 53 Cam has been extensively studied both observationally and theoretically. A model with diffusion and mass loss was recently proposed for 53 Cam to explain the surface abundance maps of several species. This model predicts steep abundance gradients of several chemical elements. 53 Cam is therefore best suited for a new investigation of the stratification of photospheric abundances. We present in this paper a spectrum synthesis analysis of several IUE high-resolution spectra of 53 Cam. Abundances derived from the ultraviolet spectra are compared to values from a previous analysis of the visible spectrum. Emergent spectra were calculated with homogeneous and stratified abundance distributions. We found that UV lines give significantly lower abundances for chromium and iron. The spectra calculated with the stratified abundance distribution predicted by the diffusion-mass loss model fit especially well IUE data for chromium lines, explaining the apparent discrepancy between the abundances from the UV and visible spectrum. Calcium, titanium and manganese were also investigated, but no definite conclusion could be drawn with the present data. The variations of UV Ti II, Cr II and Fe II lines confirm the maps derived from the visible spectrum. In particular, the titanium surface distribution is highly contrasted between the two magnetic poles. On the other hand, the variations of Ca II lines might be much weaker in UV. Our UV analysis supports the diffusion model with mass loss of 53 Cam, and gives the first evidences of the stratification of chemical elements in the photosphere of this star. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP BABEL, J (reprint author), UNIV LAUSANNE, INST ASTRON, CH-1290 CHAVANNES DES BOIS, SWITZERLAND. NR 23 TC 27 Z9 27 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 SEP PY 1992 VL 263 IS 1-2 BP 232 EP 240 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ255 UT WOS:A1992JQ25500028 ER PT J AU BERNARD, JP BOULANGER, F DESERT, FX PUGET, JL AF BERNARD, JP BOULANGER, F DESERT, FX PUGET, JL TI MODELING OF IR EMISSION OF INTERSTELLAR CLOUDS .1. EMISSION OF ISOLATED CLOUDS AND DUST ABUNDANCE VARIATIONS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE MOLECULAR CLOUDS; RADIATIVE TRANSFER; DUST; INFRARED RADIATION ID INFRARED-EMISSION; MOLECULAR CLOUDS; GRAINS; BARNARD-5; RADIATION AB We have developed a general radiative transfer code for the continuum radiation to compute the incident radiation field inside a non-homogeneous, spherically symmetric cloud. We have included a dust emission model which takes into account IR emission by transiently heated small dust particles. The model has been applied to compute the emission at IR-submm wavelengths for a set of clouds of various extinction and density distributions, containing a dust composition similar to that of the diffuse interstellar medium. Although the model is not restricted to the hypothesis adopted in this paper, we assumed that the clouds are heated only by the diffuse interstellar radiation field. We give, for a wide range of density distributions and total mass, the global emission of the cloud from IR to Submm wavelengths. We also present and discuss the spatial and spectral distribution of this emission and the characteristics of the radiation field through the cloud. At IRAS wavelengths, we find that the Limb Brightening (LB) is expected to appear in all the IRAS bands if the total extinctions toward the cloud center exceeds 4-10 mag. IRAS color as 12/100 or 25/100 are predicted to decrease continuously from the edge to the center of the cloud for constant dust composition into the cloud. Comparison of these results with the IRAS data suggest that the actual color variations can only be explained by variations of dust abundance rather than by radiative transfer effects. This implies that halos with an increased abundance of small dust particles must be present around clouds showing limb brightening at short IRAS wavelengths. Possible influences of halos on the equilibrium temperature of small and bigger dust grains in dense clouds and on the associated FIR-Submm cloud emission is also investigated. The 100 mum surface brightness is predicted to be proportional to the total column density only in the outer regions of the clouds but it can be used to estimate column densities up to extinctions of 5 - 10 mag if the inhomogeneities in the cloud envelope emitting most of the 100 mum radiation are small enough. For higher extinctions (A(V) > 10 mag), the model predicts a significant LB at 100 mum which we attribute to the decrease of the temperature and emission of the bigger grains inside the cloud. As a consequence, the 100 mum surface brightness is limited to congruent-to 20 MJy/sr for any model, independent of column density. In the FIR-Submm, the LB effect progressively disappear and the global emission of the cloud becomes progressively proportional to its mass. C1 OBSERV MEUDON, DEMIRM, F-92195 MEUDON, FRANCE. CALTECH, JET PROP LAB, PASADENA, CA 91125 USA. CALTECH, IPAC, PASADENA, CA 91125 USA. RP BERNARD, JP (reprint author), IAS, BAT 120, CAMPUS ORSAY, F-91405 ORSAY, FRANCE. NR 25 TC 45 Z9 45 U1 0 U2 2 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 SEP PY 1992 VL 263 IS 1-2 BP 258 EP 274 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ255 UT WOS:A1992JQ25500031 ER PT J AU SEKANINA, Z LARSON, SM HAINAUT, O SMETTE, A WEST, RM AF SEKANINA, Z LARSON, SM HAINAUT, O SMETTE, A WEST, RM TI MAJOR OUTBURST OF PERIODIC COMET HALLEY AT A HELIOCENTRIC DISTANCE OF 14 AU SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COMETS; P/HALLEY; COMA; OUTBURST; DUST ID AMORPHOUS WATER ICE; INFRARED SPECTRAL PROPERTIES; DUST-EMISSION; P/HALLEY; GAS; NUCLEUS; TEMPERATURE; MORPHOLOGY; EVOLUTION; ABUNDANCE AB Using a collection of deep CCD high-resolution images obtained in February-March 1991 at the European Southern Observatory, we investigate the properties and evolution of the major outburst experienced by Halley's comet at 14 AU from the Sun, some 5. years after perihelion. It is found that the ob-served crescent-shaped halo represents a segment of a conical surface populated by particulate ejecta that had been released from a suddenly activated source on the sunlit hemisphere of the comet's rotating nucleus. It is shown that the ejecta's total mass was at least approximately 10(12) g and that carbon monoxide was the most likely prime driver, accelerating the smallest grains (approximately 1 mum across) to a terminal velocity of approximately 45 m/s. The mass loading of the gas flow by the particulate matter (which includes water ice) is found to be enormous, its mass production rate exceeding the expected production rate of carbon monoxide by a factor of several tens. The derived particle size distribution function of the ejecta, g(a)da, appears to be relatively flat, is-proportional-to a-3.7 da for larger grains and is-proportional-to a-2.3 da for smaller grains, the dividing radius of approximately 14 mum in one particular scenario corresponding to particles populating the area of the secondary peak seen about midway from the nucleus to the halo's boundary. For the adopted rotation model, the production rate of the solids peaks shortly before the source's local noon, but the integrated contribution from the afternoon ejecta slightly exceeds that from the morning ejecta. The problem of this event's triggering mechanism is also addressed. C1 EUROPEAN SO OBSERV, W-8046 GARCHING, GERMANY. EUROPEAN SO OBSERV, SANTIAGO, CHILE. UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. RP SEKANINA, Z (reprint author), JET PROP LAB, MS 169-237, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 74 TC 34 Z9 34 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 1992 VL 263 IS 1-2 BP 367 EP 386 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JQ255 UT WOS:A1992JQ25500042 ER PT J AU HUBENY, I LANZ, T AF HUBENY, I LANZ, T TI ACCELERATED COMPLETE-LINEARIZATION METHOD FOR CALCULATING NLTE MODEL STELLAR ATMOSPHERES SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE RADIATIVE TRANSFER; STARS, ATMOSPHERES; STARS, EARLY-TYPE ID APPROXIMATE LAMBDA OPERATORS AB Two approaches to accelerating the method of complete linearization for calculating NLTE model stellar atmospheres are suggested. The first one, the so-called Kantorovich variant of the Newton-Raphson method, consists of keeping the Jacobi matrix of the system fixed, which allows us to calculate the costly matrix inversions only a few times and then keep them fixed during the subsequent computations. The second method is an application of the Ng acceleration. Both methods are extremely easy to implement with any model atmosphere code based on complete linearization. It is demonstrated that both methods, and especially their combination, yield a rapidly and globally convergent algorithm, which takes 2 to 5 times less computer time, depending on the model at hand and the required accuracy, than the ordinary complete linearization. Generally, the time gain is more significant for more complicated models. The methods were tested for a broad range of atmospheric parameters (T(eff) = 10 000, 25 000 and 50 000 K), and in all cases they exhibited similar behavior. Ng acceleration applied on the Kantorovich variant thus offers a significant improvement of the standard complete-linearization method, and may now be used for calculating relatively involved NLTE model stellar atmospheres. RP HUBENY, I (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 681, GREENBELT, MD 20771 USA. NR 32 TC 131 Z9 133 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 SEP PY 1992 VL 262 IS 2 BP 501 EP 514 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM038 UT WOS:A1992JM03800020 ER PT J AU LEVIN, S BENSADOUN, M BERSANELLI, M DEAMICI, G KOGUT, A LIMON, M SMOOT, G AF LEVIN, S BENSADOUN, M BERSANELLI, M DEAMICI, G KOGUT, A LIMON, M SMOOT, G TI A MEASUREMENT OF THE COSMIC MICROWAVE BACKGROUND TEMPERATURE AT 7.5 GHZ SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND ID RADIATION; SPECTRUM; WAVELENGTH AB We have measured the temperature of the cosmic microwave background (CMB) radiation at a frequency of 7.5 GHz (4 cm wavelength), obtaining a brightness temperature of T(CMB) = 2.70 +/- 0.08 K (68% confidence level). The measurement was made from a site near the geographical South Pole during the austral spring of 1989 and was part of an international collaboration to measure the CMB spectrum at low frequencies with a variety of radiometers from several different sites. This recent result is in agreement with our 1988 measurement at the same frequency, which was made from a different site with significantly different systematic errors. The combined result of the 1988 and 1989 measurements is 2.64 +/- 0.06 K. C1 LAWRENCE BERKELEY LAB, SPACE SCI LAB, BERKELEY, CA 94720 USA. LAWRENCE BERKELEY LAB, BERKELEY, CA 94720 USA. NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. CNR, IFC, I-20133 MILAN, ITALY. RI Kogut, Alan/D-6293-2012 NR 11 TC 20 Z9 20 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 SEP 1 PY 1992 VL 396 IS 1 BP 3 EP 9 DI 10.1086/171692 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ358 UT WOS:A1992JJ35800002 ER PT J AU FREEDMAN, WL MADORE, BF HAWLEY, SL HOROWITZ, IK MOULD, J NAVARRETE, M SALLMEN, S AF FREEDMAN, WL MADORE, BF HAWLEY, SL HOROWITZ, IK MOULD, J NAVARRETE, M SALLMEN, S TI NEW CEPHEID DISTANCES TO NEARBY GALAXIES BASED ON BVRI CCD PHOTOMETRY .3. NGC-300 SO ASTROPHYSICAL JOURNAL LA English DT Article DE CEPHEIDS; GALAXIES, DISTANCES AND REDSHIFTS; GALAXIES, INDIVIDUAL (NGC-300); LOCAL GROUP; TECHNIQUES, PHOTOMETRIC ID SCULPTOR GROUP GALAXIES; LOCAL VELOCITY-FIELD; HUBBLE CONSTANT; STARS; REGULARITY; IC-1613; STEPS AB A true distance modulus of (m - M)0 = 26.66 +/- 0.10 mag (corresponding to 2.1 +/- 0.1 Mpc) has been determined for the Sculptor Group spiral galaxy NGC 300. New CCD data have been obtained for a sample of known Cepheids in this galaxy from which apparent distance moduli at B, V, R, and I wavelengths are determined. Combining the data available at different wavelengths, and assuming a true distance modulus to the LMC of 18.5 mag, a true distance modulus is obtained for NGC 300, corrected for the effects of interstellar reddening. The availability of a new distance to NGC 300 brings to five the total number of galaxies with new CCD photometry of Cepheids, useful for calibration of the Hubble constant. C1 CALTECH,JET PROPULS LAB 100-22,CTR INFRARED PROC & ANAL,NASA,IPAC,PASADENA,CA 91125. LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94550. CALTECH,DIV PHYS MATH & ASTRON,PASADENA,CA 91125. NATL OPT ASTRON OBSERV,CERRO TOLOLO INTER AMER OBSERV,LA SERENA 1353,CHILE. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. RP FREEDMAN, WL (reprint author), CARNEGIE INST WASHINGTON,THE OBSERV,813 SANTA BARBARA ST,BALTIMORE,MD 21210, USA. NR 25 TC 81 Z9 81 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1992 VL 396 IS 1 BP 80 EP & DI 10.1086/171698 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ358 UT WOS:A1992JJ35800008 ER PT J AU BREGMAN, JD BOOTH, J GILMORE, DK KAY, L RANK, D AF BREGMAN, JD BOOTH, J GILMORE, DK KAY, L RANK, D TI EXTENDED INFRARED-EMISSION AROUND IRAS 21282+5050 SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, GENERAL; ISM, MOLECULES; PLANETARY NEBULAE, INDIVIDUAL (IRAS 21282+5050) ID BANDS; FEATURES; DUST AB Multi-aperture 3-4-mu-m spectra along with K- and L-band images of the compact planetary nebula IRAS 21282 + 5050 show a 5"-20' diameter nebula with structure similar to many other planetary nebulae. The spectral observations and the L-band image show evidence for extended PAH emission out to a radius of 20", while the K-band image shows a 5" diameter nebula. An observed linear increase of integrated brightness with aperture size at L band implies a 1/r2 volume emissivity for a spherically symmetric model. The spectral similarity of the emission in the small and large apertures suggests fluorescent emission by the PAHs. If the observed emission is from PAHs which formed during the planetary nebulae stage of IRAS 21282 + 5050, then PAHs have been forming for greater-than-or-equal-to 3000 yr. If the PAH emission is from material produced during the earlier red giant phase, then the formation time frame was much longer. The morphological and spectral similarity of IRAS 21282 + 5050 to many other planetary nebulae suggests that this phenomenon may be widespread, and that planetary nebulae may be a significant source of interstellar PAHs. C1 COLUMBIA UNIV BARNARD COLL,NEW YORK,NY 10027. UNIV CALIF SANTA CRUZ,UCO,SANTA CRUZ,CA 95064. UNIV CALIF SANTA CRUZ,LICK OBSERV,SANTA CRUZ,CA 95064. RP BREGMAN, JD (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,M5245-6,MOFFETT FIELD,CA 94035, USA. NR 14 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 SEP 1 PY 1992 VL 396 IS 1 BP 120 EP 123 DI 10.1086/171702 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ358 UT WOS:A1992JJ35800012 ER PT J AU DEJAGER, OC HARDING, AK AF DEJAGER, OC HARDING, AK TI THE EXPECTED HIGH-ENERGY TO ULTRA HIGH-ENERGY GAMMA-RAY SPECTRUM OF THE CRAB-NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, THEORY; ISM, INDIVIDUAL (CRAB NEBULA); PULSARS, INDIVIDUAL (CRAB NEBULA); RADIATION MECHANISMS, SYNCHROTRON AND INVERSE COMPTON ID PULSAR WINDS; ACCELERATION; SHOCK AB In this paper we reexamine the inverse Compton scattering model for the unpulsed TeV emission from the Crab Nebula, using the magnetic field distribution derived from MHD flow models of the nebula. We show that the observed flux can be explained if the average nebular field is indeed almost-equal-to 3 x 10(-4) G as is predicted by the spectral break between radio and optical. The calculated spectral index at TeV energies also agrees with the observed value. The only free parameter in the TeV gamma-ray flux estimate is sigma, i.e., the ratio between the electromagnetic and particle pressures at the pulsar wind shock. From the TeV data we find sigma less-than-or-equal-to 0.003, which is also consistent with previous estimates from MHD flow models which suggested that sigma almost-equal-to 0.001-0.003. The brightness distribution of the TeV gamma-ray signal is expected to extend out to almost-equal-to 1'5 from the pulsar which may be resolved with the next generation of imaging air Cherenkov telescopes. The flux of unpulsed high-energy gamma-rays seen by COS B is too high to be explained by this inverse Compton component but could be explained by synchrotron radiation requiring electrons with energies up to at least 10(16) eV, possibly accelerated at the shock in the pulsar wind. Our estimates also predict a steady flux of unpulsed ultra-high-energy gamma-rays due to the inverse Compton scattering of soft photons by such shock-accelerated electrons and/or positrons in the vicinity of the shock which should be detectable with sensitive extensive air shower detectors if sigma < 0.003. The observable gamma-ray spectrum between a few hundred MeV and almost-equal-to 1 PeV can provide us with a good estimate of the magnetic field distribution and the maximum acceleration energy in the nebula. RP DEJAGER, OC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,CODE 665,GREENBELT,MD 20771, USA. RI Harding, Alice/D-3160-2012 NR 43 TC 180 Z9 180 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 SEP 1 PY 1992 VL 396 IS 1 BP 161 EP 172 DI 10.1086/171706 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ358 UT WOS:A1992JJ35800016 ER PT J AU HERTZ, P VAUGHAN, B WOOD, KS NORRIS, JP MITSUDA, K MICHELSON, PF DOTANI, T AF HERTZ, P VAUGHAN, B WOOD, KS NORRIS, JP MITSUDA, K MICHELSON, PF DOTANI, T TI X-RAY VARIABILITY OF SCORPIUS X-1 DURING A MULTIWAVELENGTH CAMPAIGN SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, CLOSE; STARS, INDIVIDUAL (SCORPIUS X-1); STARS, VARIABLES, OTHER; X-RAYS, STARS ID QUASI-PERIODIC OSCILLATIONS; CYGNUS X-2; SPECTRAL BEHAVIOR; BINARIES; RADIO; ULTRAVIOLET; SEARCHES; GINGA; IUE AB Scorpius X-1 was observed with the Japanese X-ray satellite Ginga on 1989 March 9-11 as part of a multiwavelength campaign. The source was observed to be on the flaring branch for the first 31 hr, on the lower normal branch for the next 7 hr, and on the flaring branch during a brief observation 17 hr after the final normal branch observation. We constructed a standard color-color, or Z-, diagram for Sco X-1. We then parameterized the state of Sco X-1 by determining s(Z), the distance along the Z-diagram from the flaring branch-normal branch vertex, as a function of time. Sco X-1 moved smoothly and continuously through the Z-diagram and was never observed to jump from one branch to another. All observed spectral characteristics (intensity, X-ray hardness ratios) are well correlated with s(Z), indicating that the source changes its physical state smoothly as it moves along the Z-diagram. The tight correlation of observables with s(Z) is consistent with variation of a single physical parameter being responsible for the changes in state. There is no correlation between s(Z), the rate of change of s(Z), and observed spectral characteristics indicating that there is little, if any, hysteresis or memory in the spectral state of Sco X-1 and that motion in the Z-diagram is essentially stochastic. The range of observed values of s(Z) depends on s(Z):s(Z) always changes slowly along the flaring branch when it is near the flaring branch-normal branch vertex, but can change rapidly during the excursions up and down the flaring branch which correspond to large flares. A self-similarity is observed in the temporal profile of flares which is independent of flare amplitude. The temporal characteristics observed-including quasi-periodic oscillations, high-frequency noise, and very low frequency noise-are consistent with previous observations of Sco X-1. Quasi-periodic oscillations are observed on both the normal branch (6.3 Hz mean frequency) and the lower flaring branch (14.4 Hz mean frequency), but not on the upper flaring branch. Limits are placed on the fractional rms variation of quasi-periodic oscillations on the upper flaring branch of less than or similar 2% of the total intensity. The characteristics of the observed red noise components are found to vary along the flaring branch. The fractional rms variation of very low frequency noise increases from less than or similar 2% to greater than or similar to 6% as Sco X-1 moves from the flaring branch-normal branch vertex to the upper end of the flaring branch; the power-law index for very low frequency noise, alpha, remains constant along the flaring branch (alpha = 1.72 +/- 0.01). Both the rms fractional variation and the width of the high-frequency noise component vary as Sco X-1 moves out the flaring branch, with the rms fractional variation decreasing from approximately 3% to less than or similar 1% and the Gaussian rms width decreasing from approximately 15 Hz to approximately 5 Hz. No dependence on s(Z) is observed for any of the temporal characteristics. A search for coherent pulsations was made in both high time resolution optical and X-ray data. Limits on the 95% confidence limit pulsed amplitude are set at 0.10% (optical) and 0.19% (X-ray) for nu < 50 Hz and 0.26% (X-ray) for nu < 400 Hz. A search was made for optical quasi-periodic oscillations in data obtained while normal branch oscillations were observed in the Ginga data; none were seen with an upper limit to the fractional rms variation of 0.23% of the total intensity. C1 INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. STANFORD UNIV,DEPT PHYS,STANFORD,CA 94305. UNIV AMSTERDAM,ASTRON INST ANTON PANNEKOEK,1018 WB AMSTERDAM,NETHERLANDS. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP HERTZ, P (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,EO HULBURT C SPACE RES,CODE 4121,WASHINGTON,DC 20375, USA. RI Mitsuda, Kazuhisa/C-2649-2008 NR 51 TC 39 Z9 39 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 SEP 1 PY 1992 VL 396 IS 1 BP 201 EP 218 DI 10.1086/171710 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ358 UT WOS:A1992JJ35800020 ER PT J AU BENNETT, CL SMOOT, GF HINSHAW, G WRIGHT, EL KOGUT, A DEAMICI, G MEYER, SS WEISS, R WILKINSON, DT GULKIS, S JANSSEN, M BOGGESS, NW CHENG, ES HAUSER, MG KELSALL, T MATHER, JC MOSELEY, SH MURDOCK, TL SILVERBERG, RF AF BENNETT, CL SMOOT, GF HINSHAW, G WRIGHT, EL KOGUT, A DEAMICI, G MEYER, SS WEISS, R WILKINSON, DT GULKIS, S JANSSEN, M BOGGESS, NW CHENG, ES HAUSER, MG KELSALL, T MATHER, JC MOSELEY, SH MURDOCK, TL SILVERBERG, RF TI PRELIMINARY SEPARATION OF GALACTIC AND COSMIC MICROWAVE EMISSION FOR THE COBE DIFFERENTIAL MICROWAVE RADIOMETER SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS; GALAXY, GENERAL ID BACKGROUND-RADIATION; CONTINUUM EMISSION; RAY ELECTRONS; 408 MHZ; FLUCTUATIONS; ANISOTROPY; REGION; GALAXY; DUST; SKY AB The COBE Differential Microwave Radiometer (DMR) anisotropy experiment is sufficiently sensitive and free from systematic errors that our knowledge of Galactic emission is a limiting factor in interpreting the measurements of the 1 yr DMR maps. In this paper we construct preliminary models of microwave emiSSion from our Galaxy based on COBE and other data for the purpose of distinguishing cosmic and Galactic signals. DMR maps, with the modeled Galactic emission removed, are fitted for a quadrupole distribution. Our best estimate of the cosmic quadrupole is found to be Q(rms) = 13 +/- 4-mu-K, (DELTA-T/T)Q = (4.8 +/- 1.5) x 10(-6). Autocorrelation functions for individual Galactic components are presented. When Galactic emission is removed from the DMR data, the residual fluctuations are virtually unaffected, and therefore they are not dominated by any known Galactic emission component. C1 LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. MIT,DEPT PHYS,CAMBRIDGE,MA 02139. JET PROP LAB,PASADENA,CA 91109. GEN RES CORP,DANVERS,MA 01923. RP BENNETT, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 685,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Kogut, Alan/D-6293-2012 NR 42 TC 202 Z9 202 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 SEP 1 PY 1992 VL 396 IS 1 BP L7 EP & DI 10.1086/186505 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ359 UT WOS:A1992JJ35900002 ER PT J AU GEZARI, DY AF GEZARI, DY TI MIDINFRARED IMAGING OF ORION BN/KL - ASTROMETRY OF IRC2 AND THE SIO MASER SO ASTROPHYSICAL JOURNAL LA English DT Article DE ASTROMETRY; INFRARED, GENERAL; ISM, INDIVIDUAL, ORION IRC2; MASERS ID MOLECULAR CLOUD; NEBULA; POSITIONS; SCALE; KL AB Array images of Orion BN/KL at nine mid-infrared (5-20-mu-m) wavelengths have revealed a subarcsecond structure near IRc2 which provides new constraints on the relationship between IRc2 and the Orion SiO maser. The infrared source positions have been improved, and IRc2 is found to be displaced 0."8 +/- 0."2 (at least 400 AU) from the SiO maser, an order of magnitude greater than the seperation assumed in the current maser model. The SiO maser and the IRc2 mid-infrared source may be physically independent objects. There are indications that IRc2 is eroded on the south side adjacent to the SiO/H2O maser cluster, suggesting that another luminous object near IRc2, most likely a stellar object associated with radio continuum point source "I", is the host for the Orion SiO maser. RP GEZARI, DY (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INFRARED ASTROPHYS BRANCH,CODE 685,GREENBELT,MD 20771, USA. NR 36 TC 27 Z9 27 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 SEP 1 PY 1992 VL 396 IS 1 BP L43 EP L47 DI 10.1086/186513 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ359 UT WOS:A1992JJ35900010 ER PT J AU SMOOT, GF BENNETT, CL KOGUT, A WRIGHT, EL AYMON, J BOGGESS, NW CHENG, ES DEAMICI, G GULKIS, S HAUSER, MG HINSHAW, G JACKSON, PD JANSSEN, M KAITA, E KELSALL, T KEEGSTRA, P LINEWEAVER, C LOEWENSTEIN, K LUBIN, P MATHER, J MEYER, SS MOSELEY, SH MURDOCK, T ROKKE, L SILVERBERG, RF TENORIO, L WEISS, R WILKINSON, DT AF SMOOT, GF BENNETT, CL KOGUT, A WRIGHT, EL AYMON, J BOGGESS, NW CHENG, ES DEAMICI, G GULKIS, S HAUSER, MG HINSHAW, G JACKSON, PD JANSSEN, M KAITA, E KELSALL, T KEEGSTRA, P LINEWEAVER, C LOEWENSTEIN, K LUBIN, P MATHER, J MEYER, SS MOSELEY, SH MURDOCK, T ROKKE, L SILVERBERG, RF TENORIO, L WEISS, R WILKINSON, DT TI STRUCTURE IN THE COBE DIFFERENTIAL MICROWAVE RADIOMETER 1ST-YEAR MAPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS ID COSMIC BACKGROUND-RADIATION; INFLATIONARY UNIVERSE; ANISOTROPIES; PERTURBATIONS AB The first year of data from the Differential Microwave Radiometers (DMR) on the Cosmic Backgoround Explorer (COBE) show statistically significant (> 7-sigma) structure that is well described as scale-invariant fluctuations with a Gaussian distribution. The major portion of the observed structure cannot be attributed to known systematic errors in the instrument, artifacts generated in the data processing, or known Galactic emission. The structure is consistent with a thermal spectrum at 31, 53, and 90 GHz as expected for cosmic microwave background anisotropy. The rms sky variation, smoothed to a total 10-degrees FWHM Gaussian, is 30 +/- 5-mu-K (DELTA-T/T = 11 x 10(-6)) for Galactic latitude \b\ > 20-degrees data with the dipole anisotropy removed. The rms cosmic quadrupole amplitude is 13 +/- 4-mu-K (DELTA-T/T almost-equal-to 5 x 10(-6)). The angular autocorrelation of the signal in each radiometer channel and cross-correlation between channels are consistent and give a primordial fluctuation power-law spectrum with index n = 1.1 +/- 0.5, and an rms-quadrupole-normalized amplitude of 16 +/- 4-mu-K (DELTA-T/T almost-equal-to 6 x 10(-6)) . These features are in accord with the Harrison-Zel'dovich (scale-invariant, n = 1) spectrum predicted by models of inflationary cosmology. The low overall fluctuation amplitude is consistent with theoretical predictions of the minimal level gravitational potential variations that would give rise to the observed present day structure. C1 LAWRENCE BERKELEY LAB,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. JET PROP LAB,PASADENA,CA 91109. HUGHES STX CORP,LANHAM,MD 20706. UNIV CALIF SANTA BARBARA,DEPT PHYS,SANTA BARBARA,CA 93106. MIT,DEPT PHYS,CAMBRIDGE,MA 02139. GEN RES CORP,DANVERS,MA 01923. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. RP SMOOT, GF (reprint author), LAWRENCE BERKELEY LAB,SPACE SCI LAB,BLDG 50-351,BERKELEY,CA 94720, USA. RI Moseley, Harvey/D-5069-2012; Kogut, Alan/D-6293-2012; Rokke, Laurie/I-5642-2015 OI Rokke, Laurie/0000-0002-5696-7240 NR 29 TC 1823 Z9 1829 U1 6 U2 79 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1992 VL 396 IS 1 BP L1 EP & DI 10.1086/186504 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ359 UT WOS:A1992JJ35900001 ER PT J AU WEISTROP, D HINTZEN, P KENNICUT, RC LIU, C LOWENTHAL, J CHENG, KP OLIVERSEN, R WOODGATE, B AF WEISTROP, D HINTZEN, P KENNICUT, RC LIU, C LOWENTHAL, J CHENG, KP OLIVERSEN, R WOODGATE, B TI AN INTERACTING GALAXY PAIR IN THE BOOTES VOID SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INTERACTIONS; GALAXIES, SEYFERT; GALAXIES, STARBURST ID EMISSION-LINE GALAXIES; STAR-FORMATION; SPIRAL GALAXIES; IRAS GALAXIES; SKY SURVEY; SPECTRA; CLASSIFICATION; DIRECTION; REGION AB We report the first identified pair of interacting galaxies in the Bootes void. The galaxies, CG 692 (IRAS 1519 + 5050) and CG 693, have redshifts 0.0572 and 0.0575, respectively, and a mutual separation of approximately 34 kpc. CG 692 is experiencing widespread star formation, at a rate estimated to be 18.4 M. yr-1. CG 693 is a Seyfert 1, the third AGN found in the Bootes void, with a small amount of extranuclear star formation. The pair is another example of interacting galaxies displaying starburst and Seyfert activity apparently triggered by the interaction. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. RP WEISTROP, D (reprint author), UNIV NEVADA,DEPT PHYS,LAS VEGAS,NV 89154, USA. NR 22 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 SEP 1 PY 1992 VL 396 IS 1 BP L23 EP L26 DI 10.1086/186508 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ359 UT WOS:A1992JJ35900005 ER PT J AU WRIGHT, EL MEYER, SS BENNETT, CL BOGGESS, NW CHENG, ES HAUSER, MG KOGUT, A LINEWEAVER, C MATHER, JC SMOOT, GF WEISS, R GULKIS, S HINSHAW, G JANSSEN, M KELSALL, T LUBIN, PM MOSELEY, SH MURDOCK, TL SHAFER, RA SILVERBERG, RF WILKINSON, DT AF WRIGHT, EL MEYER, SS BENNETT, CL BOGGESS, NW CHENG, ES HAUSER, MG KOGUT, A LINEWEAVER, C MATHER, JC SMOOT, GF WEISS, R GULKIS, S HINSHAW, G JANSSEN, M KELSALL, T LUBIN, PM MOSELEY, SH MURDOCK, TL SHAFER, RA SILVERBERG, RF WILKINSON, DT TI INTERPRETATION OF THE COSMIC MICROWAVE BACKGROUND-RADIATION ANISOTROPY DETECTED BY THE COBE DIFFERENTIAL MICROWAVE RADIOMETER SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS; COSMOLOGY, THEORY; GALAXIES, CLUSTERING ID COLD DARK MATTER; LARGE-SCALE ANISOTROPY; DENSITY-FLUCTUATIONS; UNIVERSE; NUCLEOSYNTHESIS; PERTURBATIONS; MILLIMETERS; VELOCITY AB We compare the large-scale cosmic background anisotropy detected by the COBE Differential Microwave Radiometer (DMR) instrument to the sensitive previous measurements on various angular scales, and to the predictions of a wide variety of models of structure formation driven by gravitational instability. The observed anisotropy is consistent with all previously measured upper limits and with a number of dynamical models of structure formation. For example, the data agree with an unbiased cold dark matter (CDM) model with H-0 = 50 km s-1 Mpc-1 and DELTA-M/M = 1 in a 16 Mpc radius sphere. Other models, such as CDM plus massive neutrinos [hot dark matter (HDM)], or CDM with a nonzero cosmological constant are also consistent with the COBE detection and can provide the extra power seen on 5-10,000 km s-1 scales. C1 MIT,DEPT PHYS,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. JET PROP LAB,PASADENA,CA 91109. UNIV CALIF SANTA BARBARA,DEPT PHYS,SANTA BARBARA,CA 93106. GEN RES CORP,DANVERS,MA 01923. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. RP WRIGHT, EL (reprint author), UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024, USA. RI Moseley, Harvey/D-5069-2012; Kogut, Alan/D-6293-2012 NR 39 TC 388 Z9 388 U1 0 U2 6 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1992 VL 396 IS 1 BP L13 EP L18 DI 10.1086/186506 PN 2 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JJ359 UT WOS:A1992JJ35900003 ER PT J AU DRAKE, SA SIMON, T LINSKY, JL AF DRAKE, SA SIMON, T LINSKY, JL TI RADIO-CONTINUUM AND X-RAY-PROPERTIES OF THE CORONAE OF RS CANUM-VENATICORUM AND RELATED ACTIVE BINARY-SYSTEMS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE BINARIES, CLOSE; RADIO CONTINUUM, STARS; STARS, CORONAE; STARS, INDIVIDUAL (RS CANUM-VENATICORUM); X-RAYS, STARS ID SOLAR-FLARES; ASTRONOMICAL DATA; CVN BINARIES; STARS; EMISSION; POLARIZATION; CATALOG; REGION; SUN AB We present some new radio continuum and X-ray data on the coronae of RS CVn and related active binary systems which complement those included in the previous Drake, Simon, and Linsky study of the radio emission properties of these stars. The bulk of these new radio data consists of 6 cm circular polarization measurements of 28 binaries for which we can set significant constraints (less than or similar 25%) on this quantity. Seven sources showed definite circular polarization at levels from 2% to 13%, and two others showed possible circular polarization. We also present 2 cm flux density and circular polarization measurements for 29 Dra, lambda-And, and sigma-Gem on dates for which we also have 6 cm observations. The 2 to 6 cm spectral indices for these sources range from +0.62 (lambda-And during a radio flare) to -0.5 (sigma-Gem at a low flux density level). We present new optical positions of 1" accuracy from the Hubble Space Telescope Guide Star Catalog for 8 RS CVn systems which previously had very inaccurate positional information. Comparison of these optical positions with our previously reported radio observations of these stars confirms the claimed detections of UX Com, VV Mon, and UZ Lib, disproves the possible detection of SS Boo, and transforms the nondetections of WY Cnc and PW Her into definite detections of 0.46 +/- 0.05 and 0.78 +/- 0.05 mJy, respectively. The X-ray data presented here are based on a search of the Einstein IPC Slew Catalog at the positions of 190 RS CVn and related active binary systems. We have found 49 X-ray sources at the 190 positions examined (a 26% success rate) in the IPC Slew Catalog, of which 12 appear to be new IPC sources. We have used these new X-ray data, together with those previously reported in Drake, Simon, and Linsky, to reexamine the correlations between X-ray emission and radio emission, and between X-ray emission and other stellar parameters, and find no major changes in those earlier results. Finally, in the light of the radio and X-ray emission properties of RS CVn binaries described herein, we reexamine the various proposed theoretical explanations for the emission mechanisms in these two wavelength regions. C1 UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. UNIV COLORADO, NATL INST STAND & TECHNOL, JOINT INST LAB ASTROPHYS, BOULDER, CO 80302 USA. NATL INST STAND & TECHNOL, DIV QUANTUM PHYS, GAITHERSBURG, MD USA. RP NASA, GODDARD SPACE FLIGHT CTR, ARCHIVE RES CTR, CODE 668, GREENBELT, MD 20771 USA. NR 42 TC 57 Z9 57 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 EI 1538-4365 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD SEP PY 1992 VL 82 IS 1 BP 311 EP 321 DI 10.1086/191717 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JK809 UT WOS:A1992JK80900009 ER PT J AU BHATIA, AK DOSCHEK, GA AF BHATIA, AK DOSCHEK, GA TI ATOMIC DATA AND SPECTRAL-LINE INTENSITIES FOR NE-LIKE FE-XVII SO ATOMIC DATA AND NUCLEAR DATA TABLES LA English DT Article ID COLLISION CROSS-SECTIONS; IONS; EXCITATION; STRENGTHS C1 USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375. RP BHATIA, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 17 TC 73 Z9 73 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 0092-640X J9 ATOM DATA NUCL DATA JI Atom. Data Nucl. Data Tables PD SEP PY 1992 VL 52 IS 1 BP 1 EP 23 DI 10.1016/0092-640X(92)90007-5 PG 23 WC Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Physics GA JP535 UT WOS:A1992JP53500001 ER PT J AU SPANOS, JT MILMAN, MH MINGORI, DL AF SPANOS, JT MILMAN, MH MINGORI, DL TI A NEW ALGORITHM FOR L2 OPTIMAL-MODEL REDUCTION SO AUTOMATICA LA English DT Article DE MODEL REDUCTION; OPTIMIZATION; LEAST-SQUARES APPROXIMATIONS ID LINEAR-SYSTEMS AB In this paper the quadratically optimal model reduction problem for single-input, single-output systems is considered. The reduced order model is determined by minimizing the integral of the magnitude-squared of the transfer function error. It is shown that the numerator coefficients of the optimal approximant satisfy a weighted least squares problem and, on this basis, a two-step iterative algorithm is developed combining a least squares solver with a gradient minimizer. Convergence of the proposed algorithm to stationary values of the quadratic cost function is proved. The formulation is extended to handle the frequency-weighted optimal model reduction problem. Three examples demonstrate the optimization algorithm. C1 UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024. RP SPANOS, JT (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 27 TC 71 Z9 72 U1 1 U2 1 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 SEP PY 1992 VL 28 IS 5 BP 897 EP 909 DI 10.1016/0005-1098(92)90143-4 PG 13 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA JN102 UT WOS:A1992JN10200005 ER PT J AU CLEMENT, G RESCHKE, MF VERRETT, CM WOOD, SJ AF CLEMENT, G RESCHKE, MF VERRETT, CM WOOD, SJ TI EFFECTS OF GRAVITOINERTIAL FORCE VARIATIONS ON OPTOKINETIC NYSTAGMUS AND ON PERCEPTION OF VISUAL STIMULUS ORIENTATION SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID PERIPHERAL VISION; MOTION PERCEPTION AB Recordings of horizontal and vertical eye movement were obtained with subjects exposed to vertical, horizontal, and oblique optokinetic stimulation during parabolic flight. When the optokinetic stimulation vas vertical, the upward slow phase eye velocity increased during transition from high force level to free-fall, and decreased during transition from free-fall to high force level. During optokinetic stimulation in the horizontal and oblique plane, the gravitoinertial forces of parabolic flight induced changes in the velocity of the vertical component of the eye movements, and, therefore, changes in the plane of the eye movements. Some subjects also perceived modifications in the apparent orientation of the visual motion. These findings are in agreement with previous observations on the presence of a vertical nystagmus induced by changes in plane vertical acceleration. They also suggest a close interaction of reflexive eye movements induced by graviceptor inputs and visual inputs for visual stabilization during variations of gravitoinertial force level. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,SD5,HOUSTON,TX 77058. CNRS,PHYSIOL NEUROSENSORIELLE LAB,F-75005 PARIS,FRANCE. NR 21 TC 8 Z9 9 U1 0 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1992 VL 63 IS 9 BP 771 EP 777 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JK728 UT WOS:A1992JK72800002 PM 1524532 ER PT J AU CLEMENT, G WOOD, SJ RESCHKE, MF AF CLEMENT, G WOOD, SJ RESCHKE, MF TI EFFECTS OF MICROGRAVITY ON THE INTERACTION OF VESTIBULAR AND OPTOKINETIC NYSTAGMUS IN THE VERTICAL PLANE SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID SPACELAB-1 MISSION; OCULAR REFLEX; NUCLEI; VISION AB The extent to which the slow phase velocity (SPV) of nystagmus elicited by a vertical optokinetic stimulation with constant velocity could be modulated by sinusoidal angular motion in the vertical plane was investigated under normal gravity condition and during the microgravity period of parabolic flight. In normal gravity, when the angular head motion and the optokinetic stimulation were in the same direction, the peak SPV was slower than the velocity of the optokinetic display. When the head motion and the optokinetic stimulation were in opposite directions, the peak SPV was equal to the velocity of the optokinetic display. In microgravity, the peak SPV was approximately equal to the velocity of the optokinetic display when head rotation and optokinetic stimulation were in the same direction, and was faster than the velocity of the optokinetic display when head rotation and optokinetic stimulation were in opposite directions. In addition, the interaction of vestibular and optokinetic nystagmus was found to be non-linear in microgravity, especially when the optokinetic stimulation was directed downward. These results suggest an interaction between the vestibular and the optokinetic systems modulated as a function of the gravitational state, and support the observation that visual input is more effective in reducing sensory conflict experienced in microgravity. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,SD5,HOUSTON,TX 77058. CNRS,PHYSIOL NEUROSENSORIELLE LAB,F-75005 PARIS,FRANCE. NR 26 TC 6 Z9 6 U1 0 U2 1 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 SEP PY 1992 VL 63 IS 9 BP 778 EP 784 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JK728 UT WOS:A1992JK72800003 PM 1524533 ER PT J AU CONVERTINO, VA FRITSCH, JM AF CONVERTINO, VA FRITSCH, JM TI ATTENUATION OF HUMAN CAROTID-CARDIAC VAGAL BAROREFLEX RESPONSES AFTER PHYSICAL DETRAINING SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID BLOOD-PRESSURE; EXERCISE; REFLEX AB Astronauts who are occupied with prelaunch schedules may have to limit their regular physical exercise routines. To assess a potential effect on blood pressure control, carotid baroreceptor-cardiac reflex responses of 16 men (30-45 years of age) were evaluated before and after 2 weeks of exercise detraining that followed 10 weeks of regular scheduled exercise (30 min/d, 4 d/week at 75% Vo2max). At mid-expiration, the subjects held their breath and 40 mm Hg of pressure was applied to a neck chamber for four heart beats, followed by 15-mm Hg, R-wave triggered decrements to -65 mm Hg. Changes of R-R intervals were plotted against carotid distending pressure (systolic-neck chamber pressure). After detraining, the baroreflex stimulus-response relationship had a reduced slope [4.0 +/- 0.5 vs. 2.8 +/- 0.4 msec/mmHg (p = 0.0008)] and range of response [191 +/- 19 vs. 145 +/- 17 ms (p = 0.002)]. In addition, there was a resetting of the relationship on the R-R interval axis. Both the minimum and maximum R-R interval responses to the stimulus were significantly reduced after detraining [953 +/- 32 vs. 909 +/- 36 ms (p = 0.035) and 1145 +/- 36 vs. 1054 +/- 39 (p = 0.002)]. Baseline systolic pressure did not change with detraining (1 16 +/- 2 vs. 114 +/- 2 mm Hg) and the carotid baroreceptor-cardiac response relationship did not shift on the pressure axis. These results suggest that detraining from regular exercise can compromise vagally-mediated mechanisms of blood pressure regulation. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. RP CONVERTINO, VA (reprint author), NASA,KENNEDY SPACE CTR,BIOMED OPERAT & RES OFF,MAIL CODE MD-P,HOUSTON,TX 77058, USA. NR 25 TC 11 Z9 11 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 SEP PY 1992 VL 63 IS 9 BP 785 EP 788 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JK728 UT WOS:A1992JK72800004 PM 1524534 ER PT J AU THORNTON, WE HEDGE, V COLEMAN, E URI, JJ MOORE, TP AF THORNTON, WE HEDGE, V COLEMAN, E URI, JJ MOORE, TP TI CHANGES IN LEG VOLUME DURING MICROGRAVITY SIMULATION SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID EARLY CARDIOVASCULAR ADAPTATION; ZERO GRAVITY; WEIGHTLESSNESS; HEAD AB Little published information exists regarding the magnitude and time course of cephalad fluid shift resulting from microgravity simulations. Six subjects were exposed to 150 min each at horizontal bed rest, 6-degrees head-down tilt, and horizontal water immersion. Fluid shift was estimated by calculating leg volumes from eight serial girth measurements from groin to ankle before, during, and after exposure. Results were compared with data from the first 3 h of spaceflight. By the end of exposure, total leg volume for the six subjects decreased by 2.6 +/- 0.8%, 1.7 +/- 1.2%, and 4.0 +/- 1.6% for horizontal, head-down, and immersion, respectively. Changes had plateaued for horizontal and head-down and had slowed for immersion. Relatively more fluid was lost from the lower leg than the thigh for all three conditions, particularly head-down. During the first 3 h of spaceflight, total leg volume decreased by 8.6%, and relatively more fluid was lost from the thigh than the lower leg. The difference in volume changes in microgravity and simulated microgravity may be caused by the small transverse pressures still present in ground-based simulations and the extremely nonlinear compliance of tissue. C1 UNIV HOUSTON CLEAR LAKE, HOUSTON, TX 77058 USA. GE GOVT SERV, MISS SCI OFF, HOUSTON, TX USA. RP THORNTON, WE (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, ASTRON OFF, CODE CB, HOUSTON, TX 77058 USA. NR 23 TC 28 Z9 32 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1992 VL 63 IS 9 BP 789 EP 794 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JK728 UT WOS:A1992JK72800005 PM 1524535 ER PT J AU BAGIAN, JP AF BAGIAN, JP TI COMPARISON OF PARACHUTE LANDING INJURY INCIDENCE BETWEEN STANDARD AND LOW POROSITY PARACHUTES SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB Deployment of personnel by parachute is a common practice in many types of operations, both in and out of the military. Such operations are not without hazard and are associated with injuries which commonly occur during the landing phase of deployment. Environmental factors (i.e., wind and terrain) together with parachute sink rate are thought to influence the incidence of landing injuries. This study compared the incidence of overall landing injury and landing injury by parachute type in 8,706 lumps over 3 years between 1988 and 1990 between a standard porosity round canopy and a lower sink rate low porosity round canopy. In all cases the low porosity parachute group experienced significantly (p = 0.007) fewer overall injuries and fewer injuries of every type (reductions of 77% in 1988, 81% in 1989, and 94% in 1990). Reduction of sink rate by even small amounts correlates with significant (p < 0.001) injury incidence reductions on the basis of reduced kinetic energy dissipation. Low porosity parachutes should be adopted where appropriate to reduce sink rate and hence landing injuries. Flight surgeons associated with airborne operations and who are familiar with these data can play a significant role in reducing parachute landing injuries. C1 AIR RESCUE WING 939TH,PORTLAND,OR. RP BAGIAN, JP (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,ASTRON OFF,MAIL CODE CB,HOUSTON,TX 77058, USA. NR 5 TC 6 Z9 7 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 SEP PY 1992 VL 63 IS 9 BP 802 EP 804 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JK728 UT WOS:A1992JK72800007 PM 1524537 ER PT J AU CONKIN, J BEDAHL, SR VANLIEW, HD AF CONKIN, J BEDAHL, SR VANLIEW, HD TI A COMPUTERIZED DATA-BANK OF DECOMPRESSION-SICKNESS INCIDENCE IN ALTITUDE CHAMBERS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Note AB This report describes a hypobaric decompression sickness databank (HDSD) for use with personal computers. The databank consolidates some of the decompression sickness (DCS) information that has accumulated from altitude chamber tests from 1942 to the present. The information was transcribed to a data collection form, screened for accuracy and duplication, and then added to the databank through a computer keyboard. The databank consists of two files; 63 fields contain details of the test conditions in the altitude chamber, the outcome of the test in terms of DCS and venous gas emboli, the physical characteristics af the group of subjects who underwent the test, and the denitrogenation procedures prior to decompression. The HDSD currently contains 378 records that represent 130,012 altitude exposures from 80 sources: scientific Journal articles, government and contractor reports, and chapters from books. C1 NASA,LYNDON B JOHNSON SPACE CTR,KELSEY SEYBOLD,HOUSTON,TX 77058. RP CONKIN, J (reprint author), SUNY BUFFALO,DEPT PHYSIOL,124 SHERMAN HALL,BUFFALO,NY 14214, USA. NR 12 TC 17 Z9 17 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 SEP PY 1992 VL 63 IS 9 BP 819 EP 824 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA JK728 UT WOS:A1992JK72800010 PM 1524540 ER PT J AU REMINGTON, RW SHAFTO, MG SEIFERT, CM AF REMINGTON, RW SHAFTO, MG SEIFERT, CM TI COMMENTS ON SOAR AS A THEORY OF HUMAN COGNITION SO BEHAVIORAL AND BRAIN SCIENCES LA English DT Article C1 UNIV MICHIGAN,DEPT PSYCHOL,ANN ARBOR,MI 48109. RP REMINGTON, RW (reprint author), NASA,AMES RES CTR,MAIL STOP 262-1,MOFFETT FIELD,CA 94035, USA. NR 10 TC 1 Z9 1 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0140-525X J9 BEHAV BRAIN SCI JI Behav. Brain Sci. PD SEP PY 1992 VL 15 IS 3 BP 455 EP 455 PG 1 WC Psychology, Biological; Behavioral Sciences; Neurosciences SC Psychology; Behavioral Sciences; Neurosciences & Neurology GA JN070 UT WOS:A1992JN07000018 PM 24924018 ER PT J AU SWANSON, RC TURKEL, E WHITE, JA AF SWANSON, RC TURKEL, E WHITE, JA TI AN EFFECTIVE MULTIGRID METHOD FOR HIGH-SPEED FLOWS SO COMMUNICATIONS IN APPLIED NUMERICAL METHODS LA English DT Article AB We consider the use of a multigrid method with central differencing to solve the Navier Stokes equations for high-speed flows. The time-dependent form of the equations is integrated with a Runge-Kutta scheme accelerated by local time-stepping and variable-coefficient implicit residual smoothing. Of particular importance are the details of the numerical dissipation formulation, especially the switch between the second and fourth difference terms. Solutions are given for two-dimensional laminar flow over a circular cylinder and a 15-degree compression ramp. C1 TEL AVIV UNIV,IL-69978 TEL AVIV,ISRAEL. INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. ANALYT SERV & MAT INC,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 13 TC 5 Z9 5 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0748-8025 J9 COMMUN APPL NUMER M PD SEP PY 1992 VL 8 IS 9 BP 671 EP 681 DI 10.1002/cnm.1630080913 PG 11 WC Engineering, Multidisciplinary; Mathematics, Applied SC Engineering; Mathematics GA JP255 UT WOS:A1992JP25500011 ER PT J AU THOMAS, JL AF THOMAS, JL TI AN IMPLICIT MULTIGRID SCHEME FOR HYPERSONIC STRONG-INTERACTION FLOWFIELDS SO COMMUNICATIONS IN APPLIED NUMERICAL METHODS LA English DT Article ID STOKES AB An implicit multigrid method for the compressible Navier-Stokes equations is applied to a series of two-dimensional, steady, laminar hypersonic flows over a compression ramp, including both attached and separated flow conditions. The algorithm uses upwind-biased differencing for the convective and pressure terms and central differencing for the shear-stress and heat-transfer terms. An implicit spatially factored scheme is used to advance the solution in time on a given mesh, and a V-cycle multigrid strategy is used to accelerate convergence. The multigrid algorithm provided an order of magnitude decrease in the computational time required to obtain a converged position of the separation location and enabled a substantially grid-independent result to be obtained for each of the flows considered. RP THOMAS, JL (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 8 TC 2 Z9 3 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0748-8025 J9 COMMUN APPL NUMER M PD SEP PY 1992 VL 8 IS 9 BP 683 EP 693 DI 10.1002/cnm.1630080914 PG 11 WC Engineering, Multidisciplinary; Mathematics, Applied SC Engineering; Mathematics GA JP255 UT WOS:A1992JP25500012 ER PT J AU PABONORTIZ, CU ARTONI, M AF PABONORTIZ, CU ARTONI, M TI LAGUERRE-POLYNOMIALS - NOVEL PROPERTIES AND NUMERICAL GENERATION SCHEME FOR ANALYSIS OF A DISCRETE PROBABILITY-DISTRIBUTION SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article ID PHOTON DISTRIBUTION; SQUEEZED STATES; PHASE-SPACE; OSCILLATIONS; INTERFERENCE AB We compute a quantum mechanical probability distribution expressed as a series of generalized Laguerre polynomials. A method for the numerical generation of the polynomials of any integer order is given. Two new properties of these polynomials are derived to reduce the distribution to a closed form expression involving only a single polynomial and to devise a criterion for studying the accuracy of the generation procedure. C1 NASA,GODDARD SPACE FLIGHT CTR,CODE 726,GREENBELT,MD 20771. CUNY CITY COLL,DEPT PHYS,NEW YORK,NY 10031. NR 18 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD SEP PY 1992 VL 71 IS 3 BP 215 EP 221 DI 10.1016/0010-4655(92)90010-V PG 7 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JR790 UT WOS:A1992JR79000002 ER PT J AU SULLIVAN, EC TEMKIN, A AF SULLIVAN, EC TEMKIN, A TI FURTHER DEVELOPMENTS IN THE NONITERATIVE METHOD OF SOLVING PDES IN ELECTRON-SCATTERING SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article DE ATOMIC; MOLECULAR; ELECTRON SCATTERING; ELECTRON MOLECULE SCATTERING; 3-DIMENSIONAL ELLIPTIC PARTIAL DIFFERENTIAL EQUATIONS; NONITERATIVE SOLUTION; LARGE BANDED LINEAR SYSTEMS; RECTANGULAR BOUNDARY CONDITIONS AB Our previous program to solve noniteratively two-dimensional (2D) partial differential equations (PDE's) using a 3-point second-order difference formula is generalized to apply to higher-dimensional PDE's using higher-order difference formulae. This has the effect of generalizing the basic matrix from block tridiagonal to a banded matrix whose width depends on the dimensionality and the difference order desired. The banded matrix is converted to a lower times an upper triangular matrix by a generalization of the original block tridiagonal technique. Thereafter the same methodology applies. The method is tested on an analytically solvable 3D model simulating electron diatomic molecular scattering including the vibrational degree of freedom. RP SULLIVAN, EC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 5 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD SEP PY 1992 VL 71 IS 3 BP 319 EP 342 DI 10.1016/0010-4655(92)90017-S PG 24 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JR790 UT WOS:A1992JR79000009 ER PT J AU EDWARDS, TA AF EDWARDS, TA TI FLUID CHEMISTRY MODELING FOR HYPERSONIC FLIGHT ANALYSIS SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article AB Design studies are underway for a variety of hypersonic flight vehicles. The National Aero-Space Plane will provide a reusable, single-stage-to-orbit capability for routine access to low earth orbit. Flight-capable satellites will dip into the atmosphere to maneuver to new orbits, while planetary probes will decelerate at their destination by atmospheric aerobraking. To supplement limited experimental capabilities in the hypersonic regime, computational fluid dynamics is being used to analyze the flow about these configurations. The governing equations include fluid dynamic as well as chemical species equations, which are being solved with new, robust numerical algorithms. Examples of CFD applications to hypersonic vehicles suggest an important role this technology will play in the development of future aerospace systems. The computational resources needed to obtain solutions are large, but solution-adaptive grids, convergence acceleration, and parallel processing may make run times manageable. RP EDWARDS, TA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 14 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0898-1221 J9 COMPUT MATH APPL JI Comput. Math. Appl. PD SEP PY 1992 VL 24 IS 5-6 BP 25 EP 36 DI 10.1016/0898-1221(92)90038-J PG 12 WC Mathematics, Applied SC Mathematics GA JF269 UT WOS:A1992JF26900003 ER PT J AU SAMAREHABOLHASSANI, J SMITH, RE AF SAMAREHABOLHASSANI, J SMITH, RE TI A PRACTICAL APPROACH TO ALGEBRAIC GRID ADAPTION SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article AB Algebraic grid-adaption is discussed and a method with the capability to simultaneously adapt to several variables is described. This method makes it possible to resolve several gradients in a flow-field such as gradients in velocity, pressure, and Mach number. The method is incorporated into an algorithm and applied to hypersonic flow computations about two blunt bodies. The algorithm is called PRACTICAL because it allows a user to specify the resolution of several variables in a solution in an interactive manner. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP SAMAREHABOLHASSANI, J (reprint author), COMP SCI CORP,HAMPTON,VA 23666, USA. NR 10 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 0898-1221 J9 COMPUT MATH APPL JI Comput. Math. Appl. PD SEP PY 1992 VL 24 IS 5-6 BP 69 EP 81 DI 10.1016/0898-1221(92)90042-G PG 13 WC Computer Science, Interdisciplinary Applications; Mathematics, Applied SC Computer Science; Mathematics GA JF269 UT WOS:A1992JF26900007 ER PT J AU DOLINAR, S KO, TM MCELIECE, R AF DOLINAR, S KO, TM MCELIECE, R TI SOME VLSI DECOMPOSITIONS OF THE DEBRUIJN GRAPH SO DISCRETE MATHEMATICS LA English DT Article AB We define a VLSI decomposition of a directed graph G to be a collection of isomorphic vertex-disjoint subgraphs of G which together contain all of G's vertices. We call the isomorphic subgraphs comprising the decomposition building blocks for the graph G, and we refer to the edges contained in the collection of subgraphs as internal edges. The efficiency of a VLSI decomposition of G is the fraction of the total number of edges in G which are internal edges. In this paper we will present a general construction for efficient VLSI decompositions for the family of de Bruijn graphs. Using the methods to be explained in this paper, we have found a 64-chip VLSI decomposition of the de Bruijn graph B-13 with efficiency 0.754, which is being used by JPL design engineers to build a single-board Viterbi decoder for the K = 15, rate 1/4 convolutional code which will be used on NASA's Galileo mission. C1 CALTECH,DEPT ELECT ENGN,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. NR 5 TC 6 Z9 6 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-365X J9 DISCRETE MATH JI Discret. Math. PD SEP 1 PY 1992 VL 106 BP 189 EP 198 DI 10.1016/0012-365X(92)90546-R PG 10 WC Mathematics SC Mathematics GA JM738 UT WOS:A1992JM73800024 ER PT J AU SHIVAKUMAR, KN NEWMAN, JC AF SHIVAKUMAR, KN NEWMAN, JC TI VERIFICATION OF EFFECTIVE THICKNESSES FOR SIDE-GROOVED COMPACT SPECIMENS SO ENGINEERING FRACTURE MECHANICS LA English DT Article ID CRACK AB Three-dimensional elastic-plastic finite element analyses of smooth and 25% side-grooved compact specimens were conducted to verify the effective thicknesses used in the ASTM E-813 J-R curve testing procedure. The analysis showed that the current effective thickness definitions used in E-813 for calculating the elastic stress intensity factor, B(e) = square-root (BB(N)), and the plastic component of the J-integral, B(e) = B(N), are accurate, where B and B(N), are the nominal specimen thickness and thickness at the crack plane, respectively. The effective thickness, B(e) = B{1-(1-B(N)/B)2}, used in E-813 overestimates the compliance by about 7%. This error could be reduced to less than 1% if the effective thickness is taken as equal to the specimen total thickness, B(e) = B. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 13 TC 8 Z9 8 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0013-7944 J9 ENG FRACT MECH JI Eng. Fract. Mech. PD SEP PY 1992 VL 43 IS 2 BP 269 EP 275 DI 10.1016/0013-7944(92)90125-X PG 7 WC Mechanics SC Mechanics GA JP748 UT WOS:A1992JP74800009 ER PT J AU LONGWELL, AC CHANG, S HEBERT, A HUGHES, JB PERRY, D AF LONGWELL, AC CHANG, S HEBERT, A HUGHES, JB PERRY, D TI POLLUTION AND DEVELOPMENTAL ABNORMALITIES OF ATLANTIC FISHES SO ENVIRONMENTAL BIOLOGY OF FISHES LA English DT Article DE ICHTHYOPLANKTON; REPRODUCTION; CYTOLOGY; CYTOGENETICS; EMBRYOS; EGGS; LARVAE ID FLOUNDER PLATICHTHYS-STELLATUS; PERIPHERAL-BLOOD ERYTHROCYTES; SAN-FRANCISCO BAY; PSEUDOPLEURONECTES-AMERICANUS; ETHYL METHANESULFONATE; ORGANIC CONTAMINANTS; EASTERN MUDMINNOW; WINTER FLOUNDER; UMBRA-PYGMAEA; GERM-CELLS AB Planktonic 'eggs' of Atlantic mackerel, Scomber scombrus, provide evidence that pollution is associated with mortality, malformation, and abnormal chromosome division of fish embryos developing about the surface of the U.S. Atlantic coast. Embryo data are substantiated by the finding that adults of mackerel, window-pane flounder, Scophthalmus acquosus, and winter flounder, Pseudopleuronectes americanus, from more polluted coastal areas also have higher frequencies of mitotic abnormality than those from less polluted regions of the Mid- and North Atlantic. No ontogenetic interval escapes contamination. All are likely to be adversely influenced, resulting in considerable direct and indirect cumulative effect on total early-life survival. Development of genetic and epigenetic resistance to reproductively harmful influences of contaminants may interfere with other modifications in structure and function necessitated by natural environmental fluctuations, changes in climate, and by fishing itself. C1 NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732. RP LONGWELL, AC (reprint author), NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES CTR,MILFORD LAB,MILFORD,CT 06460, USA. NR 86 TC 40 Z9 43 U1 2 U2 11 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 SEP PY 1992 VL 35 IS 1 BP 1 EP 21 DI 10.1007/BF00001152 PG 21 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA JJ275 UT WOS:A1992JJ27500001 ER PT J AU OLLA, BL DAVIS, MW AF OLLA, BL DAVIS, MW TI PHOTOTACTIC RESPONSES OF UNFED WALLEYE POLLOCK, THERAGRA-CHALCOGRAMMA LARVAE - COMPARISONS WITH OTHER MEASURES OF CONDITION SO ENVIRONMENTAL BIOLOGY OF FISHES LA English DT Note DE BEHAVIOR; BIOASSAY; LIGHT; STARVATION; SWIMMING; SURVIVAL ID MARINE FISH LARVAE; JACK MACKEREL; STARVATION; MORTALITY; BEHAVIOR; GROWTH AB The capability of unfed walleye pollock, Theragra chalcogramma, larvae to swim horizontally towards light was used as a sensitive, sublethal measure of larval condition. At 9-degrees-C, positive phototaxis and swimming ability of larvae was fully developed by 4-6 d after hatching, then decreased steadily until death by 12 d after hatching. This measure of larval condition corresponded closely with previously established benchmarks of larval condition, including first feeding, yolksac absorption, point of no return and death by starvation. The presence and timing of behavioral deficits associated with starvation, such as decreased ability to swim, feed and avoid predators, may have significant effects on the ability of larvae to vertically migrate, avoid predators and find and capture food. RP OLLA, BL (reprint author), ALASKA FISHERIES SCI CTR,HATFIELD MARINE SCI CTR,NATL MARINE FISHERIES SERV,NEWPORT,OR 97365, USA. NR 15 TC 15 Z9 15 U1 1 U2 5 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 SEP PY 1992 VL 35 IS 1 BP 105 EP 108 DI 10.1007/BF00001164 PG 4 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA JJ275 UT WOS:A1992JJ27500013 ER PT J AU KING, RA AF KING, RA TI 3-DIMENSIONAL BOUNDARY-LAYER-TRANSITION ON A CONE AT MACH-3.5 SO EXPERIMENTS IN FLUIDS LA English DT Article AB A boundary-layer transition study on a sharp, 5-degrees half-angle cone at various angles of attack was conducted at Mach 3.5. Transition data were obtained with and without significantly reduced freestream acoustic disturbance levels. A progressive downstream and upstream motion of the transition front on the windward and leeward rays, respectively, of the cone with angle of attack was observed for the high noise level data in agreement with data trends obtained in conventional ("noisy") wind tunnels. However, the downstream movement was not observed to the same degree for the low noise level data in the present study. Transition believed to be crossflow dominated was found to be less receptive to freestream acoustic disturbances than first-mode (Tollmien-Schlichting) dominated transition. The previously-developed crossflow transition Reynolds number criterion, chi(tr,max) almost-equal-to 200, was found to be inadequate for the current case. An improved criterion is offered, which includes compressibility and flow-geometry effects. RP KING, RA (reprint author), NASA,LANGLEY RES CTR,EXPTL FLOW PHYS BRANCH,HAMPTON,VA 23665, USA. NR 28 TC 21 Z9 24 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD SEP PY 1992 VL 13 IS 5 BP 305 EP 314 PG 10 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA JP558 UT WOS:A1992JP55800003 ER PT J AU GOODING, JL AF GOODING, JL TI SOIL MINERALOGY AND CHEMISTRY ON MARS - POSSIBLE CLUES FROM SALTS AND CLAYS IN SNC METEORITES SO ICARUS LA English DT Article ID VIKING BIOLOGY EXPERIMENTS; WEATHERING PRODUCTS; THIOBACILLUS-FERROOXIDANS; SHERGOTTITE METEORITES; MARTIAN REGOLITH; NAKHLA METEORITE; OXIDIZED SULFUR; ORIGIN; EETA-79001; REFLECTANCE RP GOODING, JL (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,OFF CURATOR,SN2,HOUSTON,TX 77058, USA. NR 83 TC 144 Z9 148 U1 0 U2 13 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 SEP PY 1992 VL 99 IS 1 BP 28 EP 41 DI 10.1016/0019-1035(92)90168-7 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JU782 UT WOS:A1992JU78200003 ER PT J AU ROUSH, TL ROUSH, EA SINGER, RB LUCEY, PG AF ROUSH, TL ROUSH, EA SINGER, RB LUCEY, PG TI ESTIMATES OF ABSOLUTE FLUX AND RADIANCE FACTOR OF LOCALIZED REGIONS ON MARS IN THE 2-4 MU-M WAVELENGTH REGION SO ICARUS LA English DT Article ID REFLECTANCE SPECTROSCOPY; SURFACE REGIONS; SPECTRA; ATMOSPHERE; CALIBRATION; CARBONATES; PHOTOMETRY; MICRONS C1 KENNEDY JENKS CONSULTANTS,SAN FRANCISCO,CA 94107. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. UNIV HAWAII,DIV PLANETARY GEOSCI,HONOLULU,HI 96822. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP ROUSH, TL (reprint author), SAN FRANCISCO STATE UNIV,DEPT GEOSCI,1600 HOLLOWAY AVE,SAN FRANCISCO,CA 94132, USA. NR 39 TC 23 Z9 23 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 SEP PY 1992 VL 99 IS 1 BP 42 EP 50 DI 10.1016/0019-1035(92)90169-8 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JU782 UT WOS:A1992JU78200004 ER PT J AU SCATTERGOOD, TW LAU, EY STONE, BM AF SCATTERGOOD, TW LAU, EY STONE, BM TI TITANS AEROSOLS .1. LABORATORY INVESTIGATIONS OF SHAPES, SIZE DISTRIBUTIONS, AND AGGREGATION OF PARTICLES PRODUCED BY UV PHOTOLYSIS OF MODEL TITAN ATMOSPHERES SO ICARUS LA English DT Article C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SAN JOSE STATE UNIV,DEPT CHEM,SAN JOSE,CA 95192. RP SCATTERGOOD, TW (reprint author), SUNY STONY BROOK,DEPT EARTH & SPACE SCI,STONY BROOK,NY 11794, USA. NR 17 TC 43 Z9 43 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 SEP PY 1992 VL 99 IS 1 BP 98 EP 105 DI 10.1016/0019-1035(92)90174-6 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JU782 UT WOS:A1992JU78200009 ER PT J AU BARRIOT, JP BALMINO, G AF BARRIOT, JP BALMINO, G TI ESTIMATION OF LOCAL PLANETARY GRAVITY FIELDS USING LINE OF SIGHT GRAVITY-DATA AND AN INTEGRAL OPERATOR SO ICARUS LA English DT Article ID ILL-POSED PROBLEMS; VENUS GRAVITY; ANOMALIES; INVERSION C1 CTR NATL ETUD SPATIALES,DEPT GEODESIE TERR & PLANETAIRE,F-31055 TOULOUSE,FRANCE. RP BARRIOT, JP (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 57 TC 14 Z9 15 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 SEP PY 1992 VL 99 IS 1 BP 202 EP 224 DI 10.1016/0019-1035(92)90183-8 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JU782 UT WOS:A1992JU78200018 ER PT J AU CHA, AG IMBRIALE, WA AF CHA, AG IMBRIALE, WA TI A NEW ANALYSIS OF BEAM WAVE-GUIDE ANTENNAS CONSIDERING THE PRESENCE OF THE METAL ENCLOSURE SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB Large beam waveguide (BWG) type ground station antennas are generally designed using analysis which ignores the presence of the metallic tube enclosing the beam waveguide mirrors. The common analysis approaches are physical optics and Gaussian mode analyses. The weakness of these analyses is that they do not shed any light with regards to the effect of the metal tube. In this paper, the first known BWG analysis which considers the presence of the metal tube is presented. Numerical results of a two-mirror system using the new analysis are compared with experiments which have verified the new analysis. RP CHA, AG (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 6 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 SEP PY 1992 VL 40 IS 9 BP 1041 EP 1046 DI 10.1109/8.166529 PG 6 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JX026 UT WOS:A1992JX02600006 ER PT J AU Buttgenbach, TH LeDuc, HG Maker, PD Phillips, TG AF Buettgenbach, Thomas H. LeDuc, Henry G. Maker, Paul D. Phillips, T. G. TI Fixed Tuned Broadband Matching Structure for Submillimeter SIS Receivers SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article AB We have designed, fabricated, and tested a quasi-optical submillimeter wave receiver with an Nb / AIO(x) / Nb tunnel junction. This design incorporates a hybrid antenna fed by a planar logarithmic spiral structure in order to couple to the radiation field from the telescope. An important aspect is a novel matching circuit which requires several layers of photolithographic processing on top of the actual tunneling device, only possible with a refractory superconductor like Nb. Computer modeling of the device correctly predicted the measured bandwidth and the characteristic frequencies to within 8% as measured by SIS direct detection using a Fourier Transform Spectrometer. We have obtained a good match from 200 to 475 GHz between the antenna and a relatively large area ( 1 mu m(2)) tunnel junction with omega RnC approximate to 2-4. This compares to a matching circuit consisting of a simple open-ended inductive stub that attains only a few percent of total bandwidth in the submillimeter band or inductively tuned SIS arrays where the upper limit of operation is currently below the submillimeter band. Noise measurements were made at 318 GHz, 395 GHz, 426 GHz, and 492 GHz, yielding uncorrected double sideband receiver noise temperatures of 200 K, 230 K, 220 K, and 500 K, respectively. Using the same optics, coupling efficiencies between the receiver and the Caltech Submillimeter Telescope were found to have values approaching those achieved by the best waveguide horn based receiver systems. C1 [Buettgenbach, Thomas H.; Phillips, T. G.] CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. [LeDuc, Henry G.; Maker, Paul D.] CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Buttgenbach, TH (reprint author), CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. FU Code R contract; [NSF AST 90-15755]; [NASA NAGW-107] FX This work was supported by Grants NSF AST 90-15755, NASA NAGW-107, and by a Code R contract to JPL. NR 32 TC 26 Z9 26 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8223 EI 1558-2515 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD SEP PY 1992 VL 2 IS 3 BP 165 EP 175 DI 10.1109/77.160156 PG 11 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA V30OB UT WOS:000208824200008 ER PT J AU HINEDI, S SHAH, B AF HINEDI, S SHAH, B TI ACQUISITION PERFORMANCE OF VARIOUS QPSK CARRIER TRACKING LOOPS SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Letter AB This paper describes the frequency and phase acquisition performance of three QPSK carrier tracking loops: the MAP estimation loop, the Costas crossover loop, and the generalized Costas loop. Acquisition time and probability of acquisition as a function of both loop signal-to-noise ratio and frequency offset to loop bandwidth ratio are obtained via computer simulations for type II and III loops. It is shown that the MAP loop, which results in the smallest squaring loss for all signal-to-noise ratios, is sometimes outperformed by the other two loops in terms of acquisition time and acquisition probability. RP HINEDI, S (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 6 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD SEP PY 1992 VL 40 IS 9 BP 1426 EP 1429 DI 10.1109/26.163563 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JU037 UT WOS:A1992JU03700004 ER PT J AU KAUFMAN, YJ GAO, BC AF KAUFMAN, YJ GAO, BC TI REMOTE-SENSING OF WATER-VAPOR IN THE NEAR IR FROM EOS/MODIS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID VAS SPLIT WINDOW; PRECIPITABLE WATER; RETRIEVALS; ABSORPTION; ALGORITHM; SYSTEM; SCALE AB Remote sensing of the total column water vapor (in cloud free conditions) from the proposed MODIS instrument on the NASA's Earth Observing System requires special "water vapor" channels in the near infrared (IR). By using 2 near-IR "water vapor" channels (0.905 mum and 0.940 mum) in addition to existing "window" channels (0.865 mum and 1.24 mum), it will be possible to derive the total column water vapor amount from MODIS data. A ratio of the measured radiance in an absorbing channel at 0.940+/-0.025 mum or 0.905+/-0.015 mum to that in a nonabsorbing channel at 0.865+/-0.020 mum is proposed to retrieve the column water vapor over land. LOWTRAN-7 code was used to simulate remote sensing of water vapor over 20 different surface covers. The simulation was used to optimize the water vapor channel selection and to test the accuracy of the remote sensing method. The channel selection minimizes the uncertainty in the derived water vapor due to variations in the spectral dependence of the surface reflectance. The selection also minimizes the sensitivity of the selected channels to possible drift in the channel position. In a sensitivity analysis it is shown that the error in the directly derived water vapor amount is +/-13%. The use of additional MODIS channels reduces the errors due to the effect of haze, subpixel clouds and uncertainties in the temperature profile to +/-7%. Remote sensing of the variation of water vapor from day to day will be more accurate, because the surface reflectances vary slowly with time. The method was applied to Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data acquired from the NASA-ER2 aircraft and compared with other measurements. C1 UNIV COLORADO,CIRES,CTR STUDY EARTH SPACE,BOULDER,CO 80309. RP KAUFMAN, YJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 35 TC 174 Z9 239 U1 4 U2 26 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 SEP PY 1992 VL 30 IS 5 BP 871 EP 884 DI 10.1109/36.175321 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JZ984 UT WOS:A1992JZ98400004 ER PT J AU RANSON, KJ SAATCHI, SS AF RANSON, KJ SAATCHI, SS TI C-BAND MICROWAVE-SCATTERING FROM SMALL BALSAM FIR SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE BACKSCATTER CROSS-SECTION; CONIFER; MODELING ID BACKSCATTERING; RADAR; FOREST AB An understanding of the interactions of C-band microwave energy and vegetation canopies is important in order to effectively use air- and space-borne radar sensors for monitoring ecosystems. An experiment to examine the C-band backscattering characteristics of conifer trees was conducted using a truck-mounted scatterometer. Small (1 m tall) balsam fir (Abies balsamea) were arranged at various equidistant spacings on a platform to present canopies of varying density to the radar. C-band backscattering measurements of a range of canopy densities were acquired under different polarizations and incidence angles. In addition, physical measurements of the trees were made including leaf area index, biomass, leaf and branch angle distributions, and dielectric constant. The measured backscattering coefficient from the tree canopies increased with increasing biomass, but approached a maximum at a LAI of 2.5 and fresh biomass of 3.3 kg/m2. A backscatter model was implemented using measured canopy attributes and showed close agreement with scatterometer measurements over the range of canopy densities. Model results indicated that branches were the prime scatterers of the radar while needles were found to only slightly attenuate the radar signal. C1 CALTECH,NASA,JET PROP LAB,PASADENA,CA 91125. RP RANSON, KJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771, USA. RI Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 24 TC 11 Z9 11 U1 1 U2 4 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 SEP PY 1992 VL 30 IS 5 BP 924 EP 932 DI 10.1109/36.175327 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 JZ984 UT WOS:A1992JZ98400010 ER PT J AU ZEBKER, HA MADSEN, SN MARTIN, J WHEELER, KB MILLER, T LOU, YL ALBERTI, G VETRELLA, S CUCCI, A AF ZEBKER, HA MADSEN, SN MARTIN, J WHEELER, KB MILLER, T LOU, YL ALBERTI, G VETRELLA, S CUCCI, A TI THE TOPSAR INTERFEROMETRIC RADAR TOPOGRAPHIC MAPPING INSTRUMENT SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB We have augmented the NASA DC-8 AIRSAR instrument with a pair of C-band antennas displaced across track to form an interferometer sensitive to topographic variations of the Earth's surface. The antennas were developed by the Italian consortium Co.Ri.S.T.A., under contract to the Italian Space Agency (ASI), while the AIRSAR instrument and modifications to it supporting TOPSAR were sponsored by NASA. A new data processor was developed at JPL for producing the topographic maps, and a second processor was developed at Co.Ri.S.T.A. All the results presented below were processed at JPL. During the 1991 DC-8 flight campaign, data were acquired over several sites in the U.S. and Europe, and topographic maps were produced from several of these flight lines. Analysis of the results indicate that statistical errors are in the 2-4 m range, while systematic effects due to aircraft motion are in the 10-20 m range. Our initial results from development of a second generation processor at JPL show that aircraft motion compensation algorithms reduce the systematic variations to 2 m, while the statistical errors are reduced to 2-3 m. C1 CORISTA,NAPLES,ITALY. ALENIA SPA,ROME,ITALY. RP ZEBKER, HA (reprint author), CALTECH,NASA,JET PROP LAB,RADAR SCI & SYST STUDIES GRP,PASADENA,CA 91125, USA. RI Namikawa, Laercio/C-5559-2013 OI Namikawa, Laercio/0000-0001-7847-1804 NR 13 TC 124 Z9 129 U1 2 U2 15 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 SEP PY 1992 VL 30 IS 5 BP 933 EP 940 DI 10.1109/36.175328 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 JZ984 UT WOS:A1992JZ98400011 ER PT J AU CHANG, CY CURLANDER, JC AF CHANG, CY CURLANDER, JC TI APPLICATION OF THE MULTIPLE PRF TECHNIQUE TO RESOLVE DOPPLER CENTROID ESTIMATION AMBIGUITY FOR SPACEBORNE SAR SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SYNTHETIC-APERTURE RADARS; INSTRUMENT AB Estimation of the Doppler centroid ambiguity is a necessary element of the signal processing for synthetic aperture radar (SAR) systems with large antenna pointing errors. Without proper resolution of the Doppler centroid estimation (DCE) ambiguity, the image quality will be degraded in the system impulse response function and the geometric fidelity. Two techniques for resolution of DCE ambiguity for the spaceborne SAR are presented in this paper. They include a brief review of the range cross-correlation technique and presentation of a new technique using multiple pulse repetition frequencies (PRF's). We formulate an algorithm employing simple integer arithmetic for radar systems, such as moving target indicator radar (MTIR) systems, where the PRF's contain a large common divisor. For SAR systems, where other performance factors control selection of the PRF's, an algorithm is devised to resolve the ambiguity that uses PRF's of arbitrary numerical values. The performance of this multiple PRF technique is analyzed based on a statistical error model. An example is presented that demonstrates for the Shuttle Imaging Radar-C (SIR-C) C-band SAR, the probability of correct ambiguity resolution is higher than 95% for antenna attitude errors as large as 3-degrees. RP CHANG, CY (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 26 TC 40 Z9 43 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1992 VL 30 IS 5 BP 941 EP 949 DI 10.1109/36.175329 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 JZ984 UT WOS:A1992JZ98400012 ER PT J AU ZEBKER, HA VILLASENOR, J AF ZEBKER, HA VILLASENOR, J TI DECORRELATION IN INTERFEROMETRIC RADAR ECHOES SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID AREAS AB A radar interferometric technique for topographic mapping of surfaces promises a high resolution, globally consistent approach to generation of digital elevation models. One implementation approach, that of utilizing a single synthetic aperture radar (SAR) system in a nearly repeating orbit, is attractive not only for cost and complexity reasons but also in that it permits inference of changes in the surface over the orbit repeat cycle from the correlation properties of the radar echoes. Here we characterize the various sources contributing to the echo correlation statistics, and isolate the term which most closely describes surficial change. We then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time. We find that there is decorrelation increasing with time but that digital terrain model generation remains feasible. We present such a map of a forested area in Oregon which also includes some nearly unvegetated lava flows, and find that temporal decorrelation contributions to the height errors may be limited to 1.5 and 2.6 m for the forested and lava areas, respectively, if suitable attention is given to experiment design. Such a technique could provide a global digital terrain map. RP ZEBKER, HA (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 914 Z9 1016 U1 6 U2 37 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 SEP PY 1992 VL 30 IS 5 BP 950 EP 959 DI 10.1109/36.175330 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JZ984 UT WOS:A1992JZ98400013 ER PT J AU TSANG, L CHEN, ZX OH, S MARKS, RJ CHANG, ATC AF TSANG, L CHEN, ZX OH, S MARKS, RJ CHANG, ATC TI INVERSION OF SNOW PARAMETERS FROM PASSIVE MICROWAVE REMOTE-SENSING MEASUREMENTS BY A NEURAL NETWORK TRAINED WITH A MULTIPLE-SCATTERING MODEL SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID DENSE AB The inversion of snow parameters from passive microwave remote sensing measurements is performed with a neural network trained with a dense media multiple scattering model. The basic idea is to use the input-output pairs generated by the scattering model to train the neural network. Once the neural network is trained, it can invert snow parameters speedily from the measurements. In this paper, we have performed simultaneous inversion of three parameters: mean-grain size of ice particles in snow, snow density, and snow temperature from five brightness temperatures. The five brightness temperatures are that of 19 GHz vertical polarization, 19 GHz horizontal polarization, 22 GHz vertical polarization, 37 GHz vertical polarization, and 37 GHz horizontal polarization. It is shown that the neural network gives good results for the inversion of parameters from the simulated data computed from the dense media radiative transfer equation which includes the effects of multiple scattering. For the simulated testing data, the absolute percentage errors for mean-grain size of ice particles and snow density are less than 10%, and the absolute error for snow temperature less than is 3-degrees-K. We also use the neural network with the trained weighting coefficients of the three-parameter model to invert the SSMI data over the Antarctica region. The algorithm inverts 30 000 sets of 5-channel brightness temperatures of Antarctica in only 10 cpu min on a VAX 3500 workstation. Validity of the inversion results is discussed in view of the limited number of parameters that we used and the much more complicated real-life situation in the Antarctica. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP TSANG, L (reprint author), UNIV WASHINGTON,DEPT ELECT ENGN,SEATTLE,WA 98195, USA. NR 28 TC 59 Z9 64 U1 0 U2 6 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 SEP PY 1992 VL 30 IS 5 BP 1015 EP 1024 DI 10.1109/36.175336 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JZ984 UT WOS:A1992JZ98400019 ER PT J AU LEVINE, DM LANG, RH LIN, YQ AF LEVINE, DM LANG, RH LIN, YQ TI TRANSIENT-RESPONSE OF A LAYER OF DISCRETE RANDOM-MEDIA OVER A DIELECTRIC HALF-SPACE SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID ELECTROMAGNETIC BACKSCATTERING; MICROWAVE SCATTEROMETER; RADAR SCATTEROMETER; FOREST CANOPIES; VEGETATION AB A solution is presented in the time domain for the scattering of a short pulse incident on a layer of discrete random media. The layer consists of identical, but randomly oriented particles situated above a homogeneous (i.e., deterministic) half-space. A solution is found for the backscattered pulse when the incident pulse is obliquely incident on the layer. The solution is obtained in the case of low particle density using the distorted Born approximation. The short pulse solution is an approximation to the impulse response (Green's function) for the layer and as such can be used to compute the response to pulses of arbitrary shape. C1 GEORGE WASHINGTON UNIV,DEPT ELECT ENGN & COMP SCI,WASHINGTON,DC 20052. RP LEVINE, DM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MICROWAVE SENSORS BRANCH,GREENBELT,MD 20771, USA. NR 20 TC 5 Z9 5 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 SEP PY 1992 VL 30 IS 5 BP 1034 EP 1045 DI 10.1109/36.175338 PG 12 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JZ984 UT WOS:A1992JZ98400021 ER PT J AU TOWNSHEND, JRG JUSTICE, CO GURNEY, C MCMANUS, J AF TOWNSHEND, JRG JUSTICE, CO GURNEY, C MCMANUS, J TI THE IMPACT OF MISREGISTRATION ON CHANGE DETECTION SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SPATIAL-RESOLUTION; THEMATIC MAPPER; MODIS; LANDSAT-4; ACCURACY; SCIENCE; IMAGERY; SYSTEM AB The impact of misregistration of images on the detection of changes in land cover has been evaluated using spatially degraded Landsat MSS images. Attention is focused on simulated images of the normalized difference vegetation index (NDVI) at two of the spatial resolutions of the planned Moderate Resolution Imaging Spectrometer (MODIS), namely 250 and 500 m. In the first of two sets of experiments single-date images from seven diverse areas were first misregistered against themselves and the statistical properties of the differences were analyzed using semivariograms. In general, we would expect that the finer the spatial frequencies present within an image the greater the consequences of misregistration. The results indicate that in the absence of any actual changes to the land surface, the consequences of misregistration were very marked even for subpixel misregistrations. Pairs of images from different time periods were then misregistered. The results showed, that for four of the seven areas, an error equivalent to greater than 50% of the actual differences in the NDVI as measured by the semivariance, was induced hy a misregistration of only one pixel. To achieve an error of only 10%, registration accuracies of 0.2 pixels or less are required. All these four areas were densely covered by vegetation, whereas for the other three more sparsely vegetated areas with semiarid climates, a registration accuracy of between 0.5 and 1.0 pixel were sufficient to achieve an error of 10% or less. These results indicate that high levels of registration must be achieved by operational monitoring systems if there is to be reliable monitoring of global change. RP TOWNSHEND, JRG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771, USA. NR 29 TC 315 Z9 326 U1 2 U2 24 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 SEP PY 1992 VL 30 IS 5 BP 1054 EP 1060 DI 10.1109/36.175340 PG 7 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JZ984 UT WOS:A1992JZ98400023 ER PT J AU WU, JC KATTI, RR STADLER, HL AF WU, JC KATTI, RR STADLER, HL TI PARTIAL GROOVING IN VERTICAL BLOCH LINE MEMORY SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1992 INTERNATIONAL MAGNETICS CONF ( INTERMAG 92 ) - MAGNETIC RECORDING HEADS : INDUCTIVE THIN FILM AND LAMINATED CY APR 13-16, 1992 CL ST LOUIS, MO SP ALLEGHENY LUDLUM, ALLIED SIGNAL, APPL MAGNET, BASF MAGNET, BOHLMAN TACHNET, CRUCIBLE MAGNET, EASTMAN KODAK, F G JONES ASSOC, FUJITSU, GEC AB Partially grooved regions in magnetic garnets, used to stabilize minor-loop stripe domains in Vertical Bloch Line memories, have been investigated using arrays of grooves, in garnets with a zero-field stripe-width of 2.36-mu-m and thickness of 2.26-mu-m. Rectangular grooved regions were used to confine the minor loop stripes, using a groove depth of 10%, and groove widths of 1.5-mu-m and 2.0-mu-m. Major line regions were defined by two successive 10% grooving steps. Bias field margins were measured experimentally; and computed using a two-dimensional, magnetic-domain computer simulation. The computed margins were shown to be in quantitative agreement with experimentally measured bias field margins. Interpretation of the simulations and the experimental data in these samples assert that magnetostatic effects dominate magnetostrictive effects in defining bias field stability. RP WU, JC (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD SEP PY 1992 VL 28 IS 5 BP 2338 EP 2340 DI 10.1109/20.179484 PN 2 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA JN877 UT WOS:A1992JN87700078 ER PT J AU KATTI, RR RICE, P WU, JC STADLER, HL AF KATTI, RR RICE, P WU, JC STADLER, HL TI DOMAIN IMAGING IN MAGNETIC GARNETS USING TUNNELING-STABILIZED MAGNETIC FORCE MICROSCOPY SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1992 INTERNATIONAL MAGNETICS CONF ( INTERMAG 92 ) - MAGNETIC RECORDING HEADS : INDUCTIVE THIN FILM AND LAMINATED CY APR 13-16, 1992 CL ST LOUIS, MO SP ALLEGHENY LUDLUM, ALLIED SIGNAL, APPL MAGNET, BASF MAGNET, BOHLMAN TACHNET, CRUCIBLE MAGNET, EASTMAN KODAK, F G JONES ASSOC, FUJITSU, GEC AB Magnetic domains in low-coercivity magnetic garnets have been imaged using tunneling-stabilized magnetic force microscopy (TSMFM). In TSMFM, a triangular, Au-coated, thin-film, Ni-spring tunneling tip flexes in response to the sample's fringing magnetic field as the tip is scanned across the Au-coated garnet sample. The magnetic garnet is an epitaxial YGdTmGa/YSmTmGa film, grown on a nonmagnetic Gd3Ga5O12 (GGG) substrate, with a zero-field stripe width of 2.2-mu-m. The Ni tip does not appear to disturb the garnet's domain structure despite the garnet's low coercivity, nor does the magnetization from the garnet appear to disturb the Ni tip. The shape and period of the contrast observed with TSMFM is consistent with magnetic domain patterns measured using ferrofluid decoration and magneto-optic Faraday effect imaging. C1 NATL INST STAND & TECHNOL,BOULDER,CO 80303. RP KATTI, RR (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 7 TC 5 Z9 5 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD SEP PY 1992 VL 28 IS 5 BP 2913 EP 2915 DI 10.1109/20.179670 PN 2 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA JN877 UT WOS:A1992JN87700262 ER PT J AU ZMUIDZINAS, J LEDUC, HG AF ZMUIDZINAS, J LEDUC, HG TI QUASI-OPTICAL SLOT ANTENNA SIS MIXERS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID QUASIPARTICLE MIXERS; RADIO ASTRONOMY; JUNCTIONS; RECEIVER; NOISE; WAVELENGTHS; MILLIMETER; STRIPLINES AB We describe a new quasi-optical SIS mixer designed for efficient radiation coupling. The mixer uses a twin-slot antenna which has the advantages of a good beam pattern and a low impedance. The radiation and impedance characteristics of the antenna were obtained from a moment-method calculation. Tapered superconducting microstrip transmission lines are used to carry the radiation from the slot antennas to the tunnel junction. The effective impedance seen by the tunnel junction is quite low, about 4-OMEGA, which allows micron-size junctions to be used at 500 GHz. The mixers have been fabricated using Nb/Al-oxide/Nb tunnel junctions and a receiver noise temperature of 420 K (DSB) was measured at 490 GHz, which is the best yet obtained for a quasi-optical mixer at this frequency. The comparatively large junction area increases the mixer saturation power and allows strong suppression of noise from the Josephson effect by the application of a magnetic field of modest strength. C1 JET PROP LAB,PASADENA,CA 91109. RP ZMUIDZINAS, J (reprint author), CALTECH,GEORGE W DOWNS LAB PHYS,320-47,PASADENA,CA 91125, USA. NR 33 TC 107 Z9 108 U1 2 U2 12 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD SEP PY 1992 VL 40 IS 9 BP 1797 EP 1804 DI 10.1109/22.156607 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA JN525 UT WOS:A1992JN52500008 ER PT J AU DUGAN, JB BAVUSO, SJ BOYD, MA AF DUGAN, JB BAVUSO, SJ BOYD, MA TI DYNAMIC FAULT-TREE MODELS FOR FAULT-TOLERANT COMPUTER-SYSTEMS SO IEEE TRANSACTIONS ON RELIABILITY LA English DT Article DE FAULT TREE; SPARE; DYNAMIC REDUNDANCY; FAULT TOLERANT COMPUTER SYSTEM; HARP ID COVERAGE AB Reliability analysis of fault-tolerant computer systems for critical applications is complicated by several factors. Systems designed to achieve high levels of reliability frequently employ high levels of redundancy, dynamic redundancy management, and complex fault & error recovery techniques. This paper describes dynamic fault-tree modeling techniques for handling these difficulties. Three advanced fault-tolerant computer systems are described, viz, a fault-tolerant parallel processor, a mission a system, and a fault-tolerant hypercube. Fault-tree models for their analysis are presented. HARP (Hybrid Automated Reliability Predictor) is a software package developed at Duke University and NASA Langley Research Center that can solve those fault-tree models. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP DUGAN, JB (reprint author), DUKE UNIV,DEPT COMP SCI,DURHAM,NC 27706, USA. NR 19 TC 242 Z9 274 U1 3 U2 23 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9529 J9 IEEE T RELIAB JI IEEE Trans. Reliab. PD SEP PY 1992 VL 41 IS 3 BP 363 EP 377 DI 10.1109/24.159800 PG 15 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA JP587 UT WOS:A1992JP58700011 ER PT J AU KERCZEWSKI, RJ YU, J WALTON, JC PERL, TD ANDRO, M ALEXOVICH, RE AF KERCZEWSKI, RJ YU, J WALTON, JC PERL, TD ANDRO, M ALEXOVICH, RE TI MULTIPLE-ACCESS PHASED-ARRAY ANTENNA SIMULATOR FOR A DIGITAL BEAM-FORMING SYSTEM INVESTIGATION SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article; Proceedings Paper CT 9TH INTERNATIONAL CONF ON DIGITAL SATELLITE COMMUNICATIONS ( ICDSC-9 ) CY APR, 1992 CL COPENHAGEN, DENMARK SP INTELSAT AB Future versions of data relay satellite systems are currently being planned by NASA. Being given consideration for implementation are on-board digital beam-forming techniques which will allow multiple users to simultaneously access a single S-band phased array antenna system. To investigate the potential performance of such a system, a laboratory simulator has been developed at NASA's Lewis Research Center. This paper describes the system simulator, and in particular, the requirements, design and performance of a key subsystem, the phased array antenna simulator, which provides realistic inputs to the digital processor including multiple signals, noise and non-linearities. RP KERCZEWSKI, RJ (reprint author), NASA,LEWIS RES CTR,21000 BROOKPARK RD,MS 54-2,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0737-2884 J9 INT J SATELL COMMUN JI Int. J. Satell. Commun. PD SEP-OCT PY 1992 VL 10 IS 5 BP 293 EP 297 DI 10.1002/sat.4600100514 PG 5 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA KF947 UT WOS:A1992KF94700013 ER PT J AU SINGH, J AF SINGH, J TI THE CONSTITUTION AND MICROSTRUCTURE OF LASER SURFACE-MODIFIED METALS SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Article ID CR-AL-HF; ALLOYS; PHASE; FILMS RP SINGH, J (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 33 TC 8 Z9 8 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1047-4838 J9 JOM-J MIN MET MAT S JI JOM-J. Miner. Met. Mater. Soc. PD SEP PY 1992 VL 44 IS 9 BP 8 EP 14 PG 7 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA JM874 UT WOS:A1992JM87400002 ER PT J AU BOBBITT, RB HOWARD, RM AF BOBBITT, RB HOWARD, RM TI ESCAPE STRATEGIES FOR TURBOPROP AIRCRAFT IN MICROBURST WINDSHEAR SO JOURNAL OF AIRCRAFT LA English DT Article AB A simulation was carried out on the performance of turboprop aircraft within a microburst windshear with the intent of providing specific flight procedures for optimal navigation through the disturbance. The windshear model used was a double-vortex-ring and point-source model duplicating the severe winds of the microburst encountered by Delta Airlines Flight 191 during an approach to landing at Dallas/Ft. Worth Airport on August 2, 1985. A parameter-estimation technique was used to vary the source strength and the vortices' strengths, sizes, and locations to best match the model-generated winds with those of the recorded low-level microburst windshear. Various escape strategies were tested using the flight performance characteristics of the U.S. Navy P-3 Orion and T-44 Pegasus turboprop aircraft during the flight phases of approach to landing, takeoff, and the low-altitude anti-submarine warfare mission. The results support a constant-pitch-angle escape procedure for all configurations and situations tested. The effects of changes in weight, wing loading, thrust-to-weight ratio, and takeoff rotation speed were treated, and stick control forces required to maintain pitch attitude with an immediate loss of airspeed were measured using the P-3 flight simulator. RP BOBBITT, RB (reprint author), NASA,PATROL SQUADRON 47,MOFFETT FIELD,CA 94035, USA. NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1992 VL 29 IS 5 BP 745 EP 752 DI 10.2514/3.46241 PG 8 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300001 ER PT J AU MOSHER, M AF MOSHER, M TI EVALUATION OF DISCRETE FREQUENCY SOUND IN CLOSED-TEST-SECTION WIND TUNNELS SO JOURNAL OF AIRCRAFT LA English DT Article AB The principle objective of this study is to assess the adequacy of linear acoustic theory with an impedance wall boundary condition for modeling the detailed sound field of an acoustic source in a duct. This study compares measurements and calculations of a simple acoustic source in a rectangular concrete duct lined with foam on the walls and anechoic end terminations. Measuring acoustic pressure for 12 wave numbers provides variation in frequency and absorption characteristics of the duct walls. The study concentrates on low frequencies and low wall absorptions that correspond to measurements of low-frequency helicopter noise in a lined wind tunnel. This regime is particularly difficult to measure in wind tunnels due to high levels of the reverberant field close to the source. The standard mathematical model predicted the acoustic field poorly in the duct for the lowest frequencies, well in the near field of the higher frequencies, and inconsistently in the far field of the higher frequencies. RP MOSHER, M (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1992 VL 29 IS 5 BP 753 EP 759 DI 10.2514/3.46242 PG 7 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300002 ER PT J AU COLE, SR AF COLE, SR TI AEROELASTIC EFFECTS OF SPOILER SURFACES ON A LOW-ASPECT-RATIO RECTANGULAR WING SO JOURNAL OF AIRCRAFT LA English DT Article AB An experimental research study to determine the effectiveness of spoiler surfaces in suppressing flutter onset for a low-aspect-ratio, rectangular wing has been conducted in the Langley Transonic Dynamics Tunnel (TDT). The wing model used in this flutter test consisted of a rigid wing mounted to the wind-tunnel wall by a flexible, rectangular beam. The flexible beam was connected to the wing root and cantilever mounted to the wind-tunnel wall. The wing had a 1.5 aspect ratio based on wing semispan and a NACA 64A010 airfoil shape. The spoiler surfaces consisted of thin, rectangular aluminum plates that were vertically mounted to the wing surface. The spoiler surface geometry and location on the wing surface were varied to determine the effects of these parameters on the classical flutter of the wing model. Subsonically, the experiment showed that spoiler surfaces increased the flutter dynamic pressure with each successive increase in spoiler height or width. This subsonic increase in flutter dynamic pressure was approximately 15% for the maximum height spoiler configuration and for the maximum width spoiler configuration. At transonic Mach numbers, the flutter dynamic pressure conditions were increased even more substantially than at subsonic Mach numbers for some of the smaller spoiler surfaces. But for larger spoiler sizes (in terms of either height or width) the spoilers forced a torsional instability in the transonic regime that was highly Mach number dependent. This detrimental torsional instability was found at dynamic pressures well below the expected flutter conditions. Variations in the spanwise location of the spoiler surfaces on the wing showed little effect on flutter. Flutter analysis was conducted for the basic configuration (clean wing with all spoiler surface mass properties included). The analysis correlated well with the clean wing experimental flutter results. RP COLE, SR (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,CONFIGURAT AEROELAST BRANCH,HAMPTON,VA 23665, 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 SEP-OCT PY 1992 VL 29 IS 5 BP 768 EP 773 DI 10.2514/3.46244 PG 6 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300004 ER PT J AU YIP, LP ROSS, HM ROBELEN, DB AF YIP, LP ROSS, HM ROBELEN, DB TI MODEL FLIGHT TESTS OF A SPIN-RESISTANT TRAINER CONFIGURATION SO JOURNAL OF AIRCRAFT LA English DT Article AB Powered, radio-controlled flight tests were conducted on a 1/4-scale model of a spin-resistant trainer configuration to determine the stall departure and spin resistance characteristics provided by an outboard wing leading-edge droop modification. The model was instrumented to provide quantitative as well as qualitative information on flight characteristics. Flight test results indicated that the unmodified configuration (wing leading-edge droop off) exhibited an abrupt, uncontrollable roll departure at the stall. With the outboard wing leading-edge droop installed, the modified configuration exhibited flight characteristics that were resistant to stall departure and spin entry. The stall departure and spin resistance characteristics of the modified configuration were demonstrated in flight maneuvers that included idle-power stalls, full-power stalls, sideslip stalls, and accelerated stalls. In addition, limited quantitative flight data were obtained at various center-of-gravity locations and power settings with the model trimmed for level flight conditions in order to assess some basic aerodynamic and stability and control characteristics. The model flight results were generally in good agreement with previously obtained wind-tunnel data. RP YIP, LP (reprint author), NASA,LANGLEY RES CTR,FLIGHT RES BRANCH,DIV FLIGHT APPLICAT,MAIL STOP 247,HAMPTON,VA 23665, USA. NR 0 TC 2 Z9 2 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 SEP-OCT PY 1992 VL 29 IS 5 BP 799 EP 805 DI 10.2514/3.46248 PG 7 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300008 ER PT J AU TU, EL AF TU, EL TI NAVIER-STOKES SIMULATION OF A CLOSE-COUPLED CANARD-WING-BODY CONFIGURATION SO JOURNAL OF AIRCRAFT LA English DT Article AB The thin-layer Navier-Stokes equations are solved for the flow about a coplanar close-coupled canard-wing-body configuration at a transonic Mach number of 0.90 and at angles of attack ranging from 0 to 12 deg. The influence of the canard on the wind flowfield, including canard-wing vortex interaction and wing vortex breakdown, is investigated. A study of canard downwash and canard leading-edge vortex effects, which are the primary mechanisms of the canard-wing interaction, is emphasized. Comparisons between the computations and experimental measurements of surface pressure coefficients, lift, drag, and pitching moment data are favorable. A grid refinement study for configurations with and without canard shows that accurate results are obtained using a refined grid for angles of attack where vortex burst is present. At an angle of attack of approximately 12 deg, favorable canard-wing interaction which delays wing vortex breakdown is indicated by the computations and is in good agreement with experimental findings. RP TU, EL (reprint author), NASA,AMES RES CTR,APPL COMPUTAT FLUIDS BRANCH,MS 258-1,MOFFETT FIELD,CA 94035, USA. NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1992 VL 29 IS 5 BP 830 EP 838 DI 10.2514/3.46253 PG 9 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300013 ER PT J AU GOODSELL, AM AF GOODSELL, AM TI EULER EXPERIMENT CORRELATION OF A GENERIC FIGHTER SO JOURNAL OF AIRCRAFT LA English DT Article AB Flowfields about a generic righter model have been computed using FLO57, a three-dimensional, finite-volume Euler code. Computed pressure coefficients, forces, and moments at three Mach numbers-0.8, 1.2, and 1.6-are compared with wind-tunnel data over a wide range of angles of attack in order to determine the applicability of the code for the analysis of fighter configurations. Two configurations were studied, a wing/body and a wing/body/chine. FLO57 predicted pressure distributions, forces, and moments well at low angles of attack, at which the flow was fully attached. The FLO57 predictions were also accurate for some test conditions once the leading-edge vortex became well established. At the transonic speed, FLO57 appeared to predict vortex breakdown earlier than that seen in the experimental results. Placing the chine on the forebody delayed the onset of bursting and improved the correlation between numerical and experimental data at the subsonic conditions. RP GOODSELL, AM (reprint author), NASA,AMES RES CTR,DIV AERODYNAM,ADV AERODYNAM CONCEPTS BRANCH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1992 VL 29 IS 5 BP 839 EP 846 DI 10.2514/3.46254 PG 8 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300014 ER PT J AU ROSSOW, VJ AF ROSSOW, VJ TI 2-FENCE CONCEPT FOR EFFICIENT TRAPPING OF VORTICES ON AIRFOILS SO JOURNAL OF AIRCRAFT LA English DT Article AB Previous work on the use of a vortex trapped above a wing in order to produce high lift at low angles of attack is extended here. It is first postulated that the optimum way to trap a vortex is to design the airfoil section and wing so that the flow along the vortex core is minimized. It is then shown that a vertical fence both in front of and behind the separation bubble generated by the trapped vortex is an effective way to reduce the mass flow removal and its associated drag to a negligible amount. In order to show that vertical surfaces upstream and downstream of the vortex separation bubble have an opposite effect on the source requirements for vortex trapping, conformal mapping methods are used to obtain the solutions for a variety of simple two-dimensional, inviscid, incompressible flow configurations. Trapped-vortex flowfield solutions for the flow over flat plate and Clark-Y airfoils are then used to demonstrate that the heights of the fences can be tailored to make the required mass withdrawal (and therefore, the drag due to trapping) to be vanishingly small. RP ROSSOW, VJ (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 11 Z9 11 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1992 VL 29 IS 5 BP 847 EP 855 DI 10.2514/3.46255 PG 9 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300015 ER PT J AU WHITMORE, SA MOES, TR LARSON, TJ AF WHITMORE, SA MOES, TR LARSON, TJ TI HIGH ANGLE-OF-ATTACK FLUSH AIRDATA SENSING SYSTEM SO JOURNAL OF AIRCRAFT LA English DT Article AB A nonintrusive high angle-of-attack flush airdata sensing system (HI-FADS) was installed and flight tested on the F-18 high alpha research flight vehicle (HARV). This system measures airdata using a matrix of 25 flush-pressure orifices on the vehicle nose. Satisfactory results were obtained using all 25 ports and a symmetric subset of just 9 ports. The overall HI-FADS system design and development including hardware, air-data algorithm, and system calibration is presented. Flight test validation results are presented. Under moderate maneuvering conditions the system is shown to give excellent results. RP WHITMORE, SA (reprint author), NASA,AMES RES CTR,FLUID & FLIGHT MECH BRANCH,DRYDEN FLIGHT RES FACIL,POB 273,EDWARDS,CA 93523, USA. NR 0 TC 5 Z9 9 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1992 VL 29 IS 5 BP 915 EP 919 DI 10.2514/3.46262 PG 5 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300022 ER PT J AU CHEUNG, SH EDWARDS, TA LAWRENCE, SL AF CHEUNG, SH EDWARDS, TA LAWRENCE, SL TI APPLICATION OF COMPUTATIONAL FLUID-DYNAMICS TO SONIC-BOOM NEAR-FIELD AND MID-FIELD PREDICTION SO JOURNAL OF AIRCRAFT LA English DT Article AB A technique combining a quasilinear extrapolation theory and a three-dimensional parabolized Navier-Stokes (PNS) code has been used to calculate the supersonic overpressure from three different geometries at near- and mid-fields. Wind-tunnel data is used for code validation. Comparison of the computed results with different grid refinements, and different extrapolation distances, are shown in this article. It is observed that a large number of grid points is needed to resolve the tail shock/expansion fan interaction. Therefore, an adaptive grid approach is employed to calculate the flowfield. The effects of a thin, attached boundary layer and the sting of the wind-tunnel model to the sonic boom have also been studied in this article. The agreement between the results and the wind-tunnel data confirms that this technique can be applied to the problem of sonic-boom prediction. RP CHEUNG, SH (reprint author), NASA,AMES RES CTR,MARITIME CENT ANAL TEAM INST,MOFFETT FIELD,CA 94035, USA. NR 0 TC 8 Z9 8 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1992 VL 29 IS 5 BP 920 EP 926 DI 10.2514/3.46263 PG 7 WC Engineering, Aerospace SC Engineering GA JQ533 UT WOS:A1992JQ53300023 ER PT J AU CHOU, MD JI, GL LIOU, KN OU, SCS AF CHOU, MD JI, GL LIOU, KN OU, SCS TI CALCULATIONS OF SURFACE RADIATION IN ARID REGIONS - A CASE-STUDY SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SOLAR-RADIATION; PARAMETERIZATIONS; ABSORPTION; INSOLATION; CLIMATE; CLOUDS AB The difficulties encountered in the derivation of surface radiation budget in arid regions are studied using the surface and satellite data measured during the preliminary field experiment for the Land-Atmosphere Interactions Experiment conducted at the Heihe River basin in western China. The surface radiation is derived by coupling theoretical radiative transfer calculations with satellite cloud retrievals. Comparisons with the surface measurements of solar and thermal IR fluxes show that a large error in the computed surface fluxes occurs in some cases. The error is attributable to the lack of aerosol data, the uncertainty in cloud retrievals, and the time difference between the surface and satellite measurements. For cloud-free cases, the modeled downward solar fluxes are systematically larger than the measured fluxes. The major cause of the error appears to be the failure to include aerosols in the calculations. The error is particularly large in the afternoon hours when the ground temperature is very high (> 50-degrees-C) and the atmosphere dust content is large due to an unstable boundary layer. We find that the error can be reduced and that a good agreement between the computed and measured surface solar fluxes can be obtained by using an aerosol single-scattering albedo of 0.5 and an optical thickness of almost-equal-to 0.2 in the afternoon hours. Nevertheless, the reason for the strong absorption of solar radiation in the atmosphere remains unclear. For all the cases studied when both surface and satellite data are available, the mean errors are 4.3 and -4.7 W M-2 for the net downward surface solar flux and the downward surface IR flux, respectively. The rms errors are 17.4 and 22.1 W m-2 for the respective surface fluxes. The relatively large errors found in the cases with small cloud amounts can be explained by the fact that aerosols are often misinterpreted as clouds in the cloud retrievals. Results of this study reemphasize the importance of aerosols in surface radiation calculations. Because the diurnal variation of ground temperature is very large in the arid regions, reliable calculations of surface IR radiation require high temporal resolution for temperature measurements. Aerosol and ground-temperature retrievals from satellite data should be the highest priority in the computations of surface radiation budget over arid regions. C1 CHINESE ACAD SCI,INST PLATEAU ATMOSPHER PHYS,LANZHOU,PEOPLES R CHINA. UNIV UTAH,DEPT METEOROL,CTR ATMOSPHER & REMOTE SOUNDING STUDIES,SALT LAKE CITY,UT 84112. RP CHOU, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 22 TC 6 Z9 6 U1 0 U2 1 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 SEP PY 1992 VL 31 IS 9 BP 1084 EP 1095 DI 10.1175/1520-0450(1992)031<1084:COSRIA>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JK333 UT WOS:A1992JK33300006 ER PT J AU FATHAUER, RW GEORGE, T PIKE, WT AF FATHAUER, RW GEORGE, T PIKE, WT TI CO DIFFUSION AND GROWTH OF BURIED SINGLE-CRYSTAL COSI2 IN SI(111) BY ENDOTAXY SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID MOLECULAR-BEAM EPITAXY; SI; LAYERS AB At a growth temperature of 800-degrees-C, Co deposited on a Si capping layer exhibits oriented growth on buried CoSi2 grains on Si (111), a process referred to as endotaxy. This occurs preferentially to surface nucleation of CoSi2, provided the thickness of the Si cap is less than a critical value of almost-equal-to 100 nm for deposition rates of 0.003-0.01 nm/s. The steady-state process is modeled using known values of the Co diffusion coefficient and solid solubility in Si, allowing some conclusions to be drawn regarding parameters relevant to CoSi2 epitaxy. Using this technique, single-crystal continuous layers of CoSi2 can be formed under a high-quality Si capping layer. RP FATHAUER, RW (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 11 TC 6 Z9 6 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 1 PY 1992 VL 72 IS 5 BP 1874 EP 1878 DI 10.1063/1.351660 PG 5 WC Physics, Applied SC Physics GA JK804 UT WOS:A1992JK80400028 ER PT J AU STALLCOP, JR PARTRIDGE, H WALCH, SP LEVIN, E AF STALLCOP, JR PARTRIDGE, H WALCH, SP LEVIN, E TI H-N2 INTERACTION ENERGIES, TRANSPORT CROSS-SECTIONS, AND COLLISION INTEGRALS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID HYDROGEN-ATOMS; THEORETICAL CHARACTERIZATION; DISPERSION COEFFICIENTS; COMBINING RULE; N-2; SYSTEMS; MOLECULES; SURFACE; DIMERS; MODEL AB The energies for the interaction of a hydrogen atom with a nitrogen molecule have been calculated for large separation distances using a complete-active-space self-consistent-field/externally contracted configuration interaction method. H-N2 transport cross sections and collision integrals have been calculated using sudden approximations and a semiclassical description of the scattering. The values of these quantities are found to be close to the corresponding values determined from the average (isotropic) potential energy. The collision integrals are applied to determine diffusion and viscosity coefficients; the theoretical diffusion agrees well with the measured data available from experiments at low temperatures. C1 ELORET INST,SUNNYVALE,CA 94087. NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035. RP STALLCOP, JR (reprint author), NASA,AMES RES CTR,DIV THERMOSCI,COMP CHEM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 37 TC 37 Z9 37 U1 1 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 1 PY 1992 VL 97 IS 5 BP 3431 EP 3436 DI 10.1063/1.463956 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JL372 UT WOS:A1992JL37200063 ER PT J AU BREIDUNG, J SCHNEIDER, W THIEL, W LEE, TJ AF BREIDUNG, J SCHNEIDER, W THIEL, W LEE, TJ TI THE VIBRATIONAL FREQUENCIES OF DIFLUOROETHYNE SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID ELECTRON CORRELATION; TRIPLE EXCITATIONS; MOLECULES; SPECTRUM; FC=CF AB Ab initio coupled-cluster calculations with single and double excitations (CCSD) and with a perturbational treatment of connected triple excitations [CCSD(T)] are reported for difluoroethyne using large basis sets. The results for the trans-bending mode upsilon-4 are extremely sensitive to electron correlation and basis set effects. The best theoretical and experimental estimates for the fundamental vibrational frequencies are in excellent agreement. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP BREIDUNG, J (reprint author), UNIV GESAMTHSCH WUPPERTAL, FACHBEREICH CHEM, W-5600 WUPPERTAL 1, GERMANY. RI Lee, Timothy/K-2838-2012; Thiel, Walter/A-5677-2016 OI Thiel, Walter/0000-0001-6780-0350 NR 19 TC 13 Z9 13 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 1 PY 1992 VL 97 IS 5 BP 3498 EP 3499 DI 10.1063/1.462984 PG 2 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JL372 UT WOS:A1992JL37200069 ER PT J AU SINGH, NB GOTTLIEB, M HENNINGSEN, T HOPKINS, RH MAZELSKY, R GLICKSMAN, ME CORIELL, SR SANTORO, GJ DUVAL, WMB AF SINGH, NB GOTTLIEB, M HENNINGSEN, T HOPKINS, RH MAZELSKY, R GLICKSMAN, ME CORIELL, SR SANTORO, GJ DUVAL, WMB TI GROWTH AND CHARACTERIZATION OF LEAD BROMIDE CRYSTALS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID ELECTRO-OPTIC MATERIALS AB Lead(II) bromide was purified by a combination of directional freezing and zone-refining methods. Differential thermal analysis of the lead bromide showed that a destructive phase transformation occurs below the melting temperature. This transformation causes extensive cracking, making it very difficult to grow a large single crystal. Energy of phase transformation for pure lead bromide was determined to be 24.67 cal/g. To circumvent this limitation, crystals were doped by silver bromide which decreased the energy of phase transformation. The addition of silver helped in achieving the size, but enhanced the inhomogeneity in the crystal. The acoustic attenuation constant was almost identical for the pure and doped (below 3000 ppm) crystals. C1 RENSSELAER POLYTECH INST,DEPT MAT SCI & ENGN,TROY,NY 12180. NATL INST STAND & TECHNOL,DIV MET,GAITHERSBURG,MD 20899. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SINGH, NB (reprint author), WESTINGHOUSE ELECT CORP,CTR SCI & TECHNOL,PITTSBURGH,PA 15235, USA. OI Glicksman, Martin/0000-0002-2675-2759 NR 6 TC 18 Z9 18 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 SEP PY 1992 VL 123 IS 1-2 BP 221 EP 226 DI 10.1016/0022-0248(92)90027-G PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA JP483 UT WOS:A1992JP48300024 ER PT J AU SINGH, NB GOTTLIEB, M HENNINGSEN, T HOPKINS, RH MAZELSKY, R GLICKSMAN, ME CORIELL, SR DUVAL, WMB SANTORO, GJ AF SINGH, NB GOTTLIEB, M HENNINGSEN, T HOPKINS, RH MAZELSKY, R GLICKSMAN, ME CORIELL, SR DUVAL, WMB SANTORO, GJ TI EFFECT OF GROWTH-CONDITIONS ON THE QUALITY OF LEAD BROMIDE CRYSTALS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID ELECTRO-OPTIC MATERIALS; DIRECTIONAL SOLIDIFICATION; CONVECTION AB Single crystals of pure and doped lead bromide were grown by the Bridgman method in different convective conditions. The convection level was varied by changing the thermal and solutal Rayleigh number. The homogeneity in refractive index, and hence the optical quality, was estimated by examining the optical distortion, birefringence interferograms, and laser scattering through the crystal. The optical quality of the crystal varied significantly with the variation of convection level during the crystal growth. The critical concentration of the solute was estimated for several values of growth velocity by numerical analysis at the thermal gradient of 20 K/cm. C1 RENSSELAER POLYTECH INST,DEPT MAT SCI & ENGN,TROY,NY 12180. NATL INST STAND & TECHNOL,DIV MAT,GAITHERSBURG,MD 20899. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SINGH, NB (reprint author), WESTINGHOUSE ELECT CORP,CTR SCI & TECHNOL,PITTSBURGH,PA 15235, USA. OI Glicksman, Martin/0000-0002-2675-2759 NR 9 TC 9 Z9 9 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 SEP PY 1992 VL 123 IS 1-2 BP 227 EP 235 DI 10.1016/0022-0248(92)90028-H PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA JP483 UT WOS:A1992JP48300025 ER PT J AU LEE, AY AF LEE, AY TI A PREVIEW STEERING AUTOPILOT CONTROL ALGORITHM FOR 4-WHEEL-STEERING PASSENGER VEHICLES SO JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME LA English DT Article AB This paper addresses the control law design of a preview steering autopilot for a four-wheel-steering vehicle to perform automatic lane tracking. In the concept, an On-board computer vision system is used in lieu of the driver's vision to track the roadway. The steering autopilot design is formulated as an optimal, discrete-time preview path tracking problem under the "perfect measurement" assumption. Simulation results indicate that the tracking performance of the steering autopilot was improved by preview relative to that calculated for an autopilot without preview. These results also indicate the existence of an effective preview time with which almost all the benefits of previewing future information can be obtained. This effective preview time is about three times the reciprocal of the autopilot's bandwidth. Our study also indicates that preview steering autopilots can tolerate the use of actuators with a lower bandwidth than those designed without preview information. RP LEE, AY (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 14 TC 21 Z9 22 U1 3 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-0434 J9 J DYN SYST-T ASME JI J. Dyn. Syst. Meas. Control-Trans. ASME PD SEP PY 1992 VL 114 IS 3 BP 401 EP 408 DI 10.1115/1.2897361 PG 8 WC Automation & Control Systems; Instruments & Instrumentation SC Automation & Control Systems; Instruments & Instrumentation GA JQ649 UT WOS:A1992JQ64900010 ER PT J AU POLITES, ME AF POLITES, ME TI RECONSTRUCTING TETHERED SATELLITE SKIPROPE MOTION BY BANDPASS FILTERING MAGNETOMETER MEASUREMENTS SO JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME LA English DT Article ID DEPLOYMENT DYNAMICS AB This paper presents a unique scheme for reconstructing tethered satellite skiprope motion by ground processing satellite magnetometer measurements. The measurements are modified based on ground knowledge of the Earth's magnetic field and passed through bandpass filters tuned to the skiprope frequency. Skiprope motion is then deduced from the steady-state outputs of the filters. Simulation results are presented which verify the scheme and show it to be robust. The concept is not just limited to tethered satellites. Indeed, it can be applied whenever there is a need to reconstruct the coning motion of a body about a known axis, given measurements of a known vector in body-fixed axes. RP POLITES, ME (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,STRUCT & DYNAM LAB,DIV CONTROL SYST,HUNTSVILLE,AL 35812, USA. NR 13 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 0022-0434 J9 J DYN SYST-T ASME JI J. Dyn. Syst. Meas. Control-Trans. ASME PD SEP PY 1992 VL 114 IS 3 BP 481 EP 485 DI 10.1115/1.2897372 PG 5 WC Automation & Control Systems; Instruments & Instrumentation SC Automation & Control Systems; Instruments & Instrumentation GA JQ649 UT WOS:A1992JQ64900021 ER PT J AU KEEFE, L MOIN, P KIM, J AF KEEFE, L MOIN, P KIM, J TI THE DIMENSION OF ATTRACTORS UNDERLYING PERIODIC TURBULENT POISEUILLE FLOW SO JOURNAL OF FLUID MECHANICS LA English DT Article ID GINZBURG-LANDAU EQUATION; FULLY-DEVELOPED TURBULENCE; NAVIER-STOKES EQUATIONS; STRANGE ATTRACTORS; LYAPUNOV EXPONENTS; CHANNEL FLOW; COHERENT STRUCTURES; CHAOTIC ATTRACTORS; BENARD CONVECTION; DYNAMICAL-SYSTEMS AB Using a coarse grained (16 x 33 x 8) numerical stimulation, a lower bound on the Lyapunov dimension, D(lambda), of the attractor underlying turbulent, periodic Poiseuille flow at a pressure-gradient Reynolds number of 3200 has been calculated to be approximately 352. These results were obtained on a spatial domain with streamwise and spanwise periods of 1.6pi, and correspond to a wall-unit Reynolds number of 80. Comparison of Lyapunov exponent spectra from this and a higher-resolution (16 x 33 x 16) simulation on the same domain shows these spectra to have a universal shape when properly scaled. Using these scaling properties, and a partial exponent spectrum from a still higher-resolution (32 x 33 x 32) simulation, we argue that the actual dimension of the attractor underlying motion on the given computational domain is approximately 780. The medium resolution calculation establishes this dimension as a strong lower bound on this computational domain, while the partial exponent spectrum calculated at highest resolution provides some evidence that the attractor dimension in fully resolved turbulence is unlikely to be substantially larger. These calculations suggest that this periodic turbulent shear flow is deterministic chaos, and that a strange attractor does underly solutions to the Navier-Stokes equations in such flows. However, the magnitude of the dimension measured invalidates any notion that the global dynamics of such turbulence can be attributed to the interaction of a few degrees of freedom. Dynamical systems theory has provided the first measurement of the complexity of fully developed turbulence; the answer has been found to be dauntingly high. C1 NASA,AMES RES CTR,CTR TURBULENCE RES,MS 202A-1,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. STANFORD UNIV,STANFORD,CA 94305. OI Kim, John/0000-0002-6369-9264 NR 56 TC 54 Z9 54 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 SEP PY 1992 VL 242 BP 1 EP 29 DI 10.1017/S0022112092002258 PG 29 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JR632 UT WOS:A1992JR63200001 ER PT J AU BALACHANDAR, S STREETT, CL MALIK, MR AF BALACHANDAR, S STREETT, CL MALIK, MR TI SECONDARY INSTABILITY IN ROTATING-DISK FLOW SO JOURNAL OF FLUID MECHANICS LA English DT Article ID BOUNDARY-LAYER-TRANSITION; DISTURBANCES AB Primary instability of the three-dimensional boundary layer on a rotating disk introduces periodic modulation of the mean flow in the form of stationary crossflow vortices. Here we study the stability of this modulated mean flow with respect to secondary disturbances. These secondary disturbances are found to have quite large growth rates compared to primary disturbances. Both fundamental and subharmonic resonance cases are considered and their corresponding results indicate that the growth rate and the frequency of the secondary instability are insensitive to the exact nature of the resonance condition. The threshold primary stationary crossflow vortex amplitude for secondary instability found in this three-dimensional incompressible boundary layer is significantly larger than that for a two-dimensional boundary layer which is subjected to Tollmien-Schlichting instability. The secondary instability results in a pair of travelling counter-rotating vortices, tilted up and oriented at an angle to the primary stationary crossflow vortices. The computed velocity signals and flow visualization, evaluated based on this secondary disturbance structure, are compared with experimental results. C1 HIGH TECHNOL CORP,HAMPTON,VA 23666. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RI Balachandar, Sivaramakrishnan/E-7358-2011 NR 29 TC 30 Z9 30 U1 0 U2 2 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD SEP PY 1992 VL 242 BP 323 EP 347 DI 10.1017/S0022112092002398 PG 25 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JR632 UT WOS:A1992JR63200015 ER PT J AU BERTOLOTTI, FP HERBERT, T SPALART, PR AF BERTOLOTTI, FP HERBERT, T SPALART, PR TI LINEAR AND NONLINEAR STABILITY OF THE BLASIUS BOUNDARY-LAYER SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TOLLMIEN-SCHLICHTING WAVES; PARALLEL FLOWS AB Two new techniques for the study of the linear and nonlinear instability in growing boundary layers are presented. The first technique employs partial differential equations of parabolic type exploiting the slow change of the mean flow, disturbance velocity profiles, wavelengths, and growth rates in the streamwise direction. The second technique solves the Navier-Stokes equation for spatially evolving disturbances using buffer zones adjacent to the inflow and outflow boundaries. Results of both techniques are in excellent agreement. The linear and nonlinear development of Tollmien-Schlichting (TS) waves in the Blasius boundary layer is investigated with both techniques and with a local procedure based on a system of ordinary differential equations. The results are compared with previous work and the effects of non-parallelism and nonlinearly are clarified. The effect of nonparallelism is confirmed to be weak and, consequently, not responsible for the discrepancies between measurements and theoretical results for parallel flow. Experimental uncertainties, the adopted definition of the growth rate, and the transient initial evolution of the TS wave in vibrating-ribbon experiments probably cause the discrepancies. The effect of nonlinearity is consistent with previous weakly nonlinear theories. While nonlinear effects are small near branch I of the neutral curve, they are significant near branch II and delay or event prevent the decay of the wave. C1 OHIO STATE UNIV,DEPT MECH ENGN,COLUMBUS,OH 43210. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BERTOLOTTI, FP (reprint author), NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665, USA. NR 51 TC 246 Z9 262 U1 2 U2 23 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD SEP PY 1992 VL 242 BP 441 EP 474 DI 10.1017/S0022112092002453 PG 34 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JR632 UT WOS:A1992JR63200021 ER PT J AU TADJFAR, M BODONYI, RJ AF TADJFAR, M BODONYI, RJ TI RECEPTIVITY OF A LAMINAR BOUNDARY-LAYER TO THE INTERACTION OF A 3-DIMENSIONAL ROUGHNESS ELEMENT WITH TIME-HARMONIC FREE-STREAM DISTURBANCES SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TOLLMIEN-SCHLICHTING WAVES; SURFACE GEOMETRY; FLAT PLATE; FLOW; STABILITY; PACKET; EDGE AB Receptivity of a laminar boundary layer to the interaction of time-harmonic free-stream disturbances with a three-dimensional roughness element is studied. The three-dimensional nonlinear triple-deck equations are solved numerically to provide the basic steady-state motion. At high Reynolds numbers, the governing equations for the unsteady motion are the unsteady linearized three-dimensional triple-deck equations. These equations can only be solved numerically. In the absence of any roughness element, the free-stream disturbances, to the first order, produce the classical Stokes flow, in the thin Stokes layer near the wall (on the order of our lower deck). However, with the introduction of a small three-dimensional roughness element, the interaction between the hump and the Stokes flow introduces a spectrum of all spatial disturbances inside the boundary layer. For supercritical values of the scaled Strouhal number, S0 > 2, these Tollmien-Schlichting waves are amplified in a wedge-shaped region, 15-degrees to 18-degrees to the basic-flow direction, extending downstream of the hump. The amplification rate approaches a value slightly higher than that of two-dimensional Tollmien-Schlichting waves, as calculated by the linearized analysis, far downstream of the roughness element. C1 OHIO STATE UNIV,DEPT AERONAUT & ASTRONAUT ENGN,COLUMBUS,OH 43210. RP TADJFAR, M (reprint author), NASA,AMES RES CTR,FLUID MECH LAB,MCAT INST,MAIL STOP 260-1,MOFFETT FIELD,CA 94035, USA. NR 31 TC 12 Z9 13 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD SEP PY 1992 VL 242 BP 701 EP 720 DI 10.1017/S0022112092002544 PG 20 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JR632 UT WOS:A1992JR63200030 ER PT J AU KELLEHER, SD SILVA, LA HULTIN, HO WILHELM, KA AF KELLEHER, SD SILVA, LA HULTIN, HO WILHELM, KA TI INHIBITION OF LIPID OXIDATION DURING PROCESSING OF WASHED, MINCED ATLANTIC MACKEREL SO JOURNAL OF FOOD SCIENCE LA English DT Article DE MACKEREL; FISH; LIPID OXIDATION; MINCED MACKEREL; ANTIOXIDANTS; OXIDATION ID PEROXIDATION; MUSCLE AB An antioxidative system that was designed to maintain heme iron reduced, nonheme iron as an inactive chelate, and provide free radical scavenging in the aqueous and lipid phases, was most effective when added early in the processing of washed, minced mackerel muscle. Mince prepared from mackerel dark muscle showed greater propensity to oxidize than did the mince from light muscle. Washed mince from light muscle in the presence of the antioxidative system showed no loss of odor quality during 24 wk at -20-degrees-C. Postmortem age of the mackerel muscle had little effect on initial odor quality of the washed mince. C1 NOAA,NATL MARINE FISHERIES SERV,NATL STAND & SPECIFICAT BRANCH,GLOUCESTER,MA 01930. NOAA,NATL MARINE FISHERIES SERV,NE CTR LAB,GLOUCESTER,MA 01930. RP KELLEHER, SD (reprint author), UNIV MASSACHUSETTS AMHERST,DEPT FOOD SCI,MASSACHUSETTS AGR EXPT STN,MARINE FOODS LAB,MARINE STN,GLOUCESTER,MA 01930, USA. NR 21 TC 42 Z9 43 U1 0 U2 1 PU INST FOOD TECHNOLOGISTS PI CHICAGO PA SUITE 300 221 N LASALLE ST, CHICAGO, IL 60601-1291 SN 0022-1147 J9 J FOOD SCI JI J. Food Sci. PD SEP-OCT PY 1992 VL 57 IS 5 BP 1103 EP & DI 10.1111/j.1365-2621.1992.tb11273.x PG 0 WC Food Science & Technology SC Food Science & Technology GA JR781 UT WOS:A1992JR78100023 ER PT J AU ISHII, M SUGIURA, M IYEMORI, T SLAVIN, JA AF ISHII, M SUGIURA, M IYEMORI, T SLAVIN, JA TI CORRELATION BETWEEN MAGNETIC AND ELECTRIC-FIELD PERTURBATIONS IN THE FIELD-ALIGNED CURRENT REGIONS DEDUCED FROM DE 2 OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CURRENT-VOLTAGE RELATIONSHIP; BIRKELAND CURRENTS; EVENING SECTOR; EISCAT DATA; IONOSPHERE; CONDUCTIVITY; SOLAR; DE-2; SATELLITE; MODEL AB Satellite observations have shown high correlation between magnetic and electric field perturbations in the high-latitude field-aligned current regions. The high correlation has been interpreted by two models. In the first, the Static model, the observed perturbations are regarded as being static spatial variations, and the ratio of the orthogonal magnetic and electric field components DELTA-B(z)/E(x) represents the height-integrated ionospheric Pedersen conductivity SIGMA(P). In the second, Alfven wave model, the observed perturbations are interpreted as being Doppler-shifted Alfven waves, and the inverse of the ratio gives the Alfven wave velocity V(A). In this paper we investigate changes of this ratio with spatial scale length, using the DE 2 observations. The ratio DELTA-B(z)/E(x) is found to change little with scale length for variations of scale lengths longer than 64 km, or 8.0 s in time. While for variations of smaller scale lengths, which are obtained using numerical filters with cutoff periods shorter than 4.0 s, the same ratio shows a significant dependence on scale length. The calculated ratios are nearly equal to SIGMA(P) based on an ionospheric model for long-wavelength structures and to 1/V(A) for short-wavelength variations. The transition from the former to the latter usually begins around 4.0-8.0 s on the time scale. On the dayside the correlation between DELTA-B(z) and E(x) is generally high, and the transition is clearly seen. Thus the static model is applicable to variations of scale lengths greater than 8.0 s (or 64 km); while the Alfven wave effect becomes increasingly dominant for scale lengths less than 4.0 s (or 32 km). For scale lengths below about 5 km (approximately 0.6 s) the short-circuiting effect at ionospheric altitudes higher than the altitudes at which the horizontal Pedersen closure current usually flows becomes appreciable. However, this effect alone cannot explain the observed decrease in the ratio DELTA-B(z)/mu-0E(x). The relation between the ratio DELTA-AB(z)/mu-0E(x) and the solar zenith angle is consistent with the relationship between the Pedersen conductivity and the solar zenith angle in the published conductivity models. C1 KYOTO UNIV,FAC SCI,DATA ANAL CTR GEOMAGNETISM & SPACE MAGNETISM,KYOTO 606,JAPAN. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. TOKAI UNIV,INST RES & DEV,TOKYO 151,JAPAN. RP ISHII, M (reprint author), KYOTO UNIV,FAC SCI,DEPT GEOPHYS,KYOTO 606,JAPAN. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 30 TC 52 Z9 52 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1992 VL 97 IS A9 BP 13877 EP 13887 DI 10.1029/92JA00110 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM026 UT WOS:A1992JM02600017 ER PT J AU KAR, J MAHAJAN, KK GHOSH, S BRACE, LH AF KAR, J MAHAJAN, KK GHOSH, S BRACE, LH TI A RECONSIDERATION OF THE EFFECTS OF TERMINATOR IONOPAUSE HEIGHT ON THE NIGHTWARD ION-TRANSPORT AT VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID NIGHTSIDE IONOSPHERE; SOLAR-CYCLE; MAGNETIC-FIELDS; MAINTENANCE; DYNAMICS; MARS AB The ionopause altitude near the terminator is a crucial parameter for studies dealing with the maintenance of the nightside ionosphere of Venus. It is generally thought that during high solar wind dynamic pressures (P(SW)) or during solar minimum conditions the ionopause comes down to very low altitudes so that the dayside ionosphere is not able to supply sufficient plasma to maintain the observed nightside densities. However, there are a number of workable definitions of the ionopause. Near the terminator, the altitude of the ionopause differs considerably depending upon the definition. The ionopause deduced from the radio occultation experiment (used to study the nightward transport for solar minimum conditions) as well as the pressure ionopause can be significantly lower than the density ionopause deduced from the Langmuir probe at these locations. The latter refers to the altitude where the electron density falls to 100 cm-3. Using in situ data from the Pioneer Venus Orbiter, it is shown that the density ionopause remains fairly high even for high P(SW) conditions. Simple quantitative estimates indicate that significant flow of plasma is still possible under these conditions. Thus nightward transport of plasma during high P(SW) conditions may be more efficient than has been assumed so far. Since such conditions are more prevalent during solar cycle minimum, it is argued that transport may be relevant in the maintenance of nightside ionosphere at that time also. C1 NATL PHYS LAB,NEW DELHI 110012,INDIA. UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. RP KAR, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES BRANCH,CODE 914,GREENBELT,MD 20771, USA. NR 28 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1992 VL 97 IS A9 BP 13899 EP 13902 DI 10.1029/92JA00994 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM026 UT WOS:A1992JM02600019 ER PT J AU HEELIS, RA COLEY, WR LORANC, M HAIRSTON, MR AF HEELIS, RA COLEY, WR LORANC, M HAIRSTON, MR TI 3-DIMENSIONAL IONOSPHERIC PLASMA CIRCULATION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; CONVECTION; OUTFLOW; MODEL; FLOWS; IONS AB Examination of the ion drift velocity vector measured on the DE 2 spacecraft reveals the significance of ionospheric flows both perpendicular and parallel to the magnetic field at high latitudes. During periods of southward directed interplanetary magnetic field the familiar two-cell convection pattern perpendicular to the magnetic field is associated with field-aligned motion predominantly upward in the dayside auroral zone and cusp, and predominantly downwards in the polar cap. Friction heating by convection through the neutral gas and heating by energetic particle precipitation are believed to be responsible for the bulk of the upward flow with downward flows resulting from subsequent cooling of the plasma. Some of the upward flowing plasma is apparently given escape energy at altitudes above about 800 km. The average flow of ions across the entire high-latitude region at 400 km is outward and comparable to the energetic ion outflow observed at much higher altitudes by DE 1. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP HEELIS, RA (reprint author), UNIV TEXAS,CTR SPACE SCI,PHYS PROGRAM,MAIL STOP FO22,BOX 830688,RICHARDSON,TX 75083, USA. NR 18 TC 19 Z9 19 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1992 VL 97 IS A9 BP 13903 EP 13910 DI 10.1029/92JA00872 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JM026 UT WOS:A1992JM02600020 ER PT J AU CHIANG, RY SAFONOV, MG AF CHIANG, RY SAFONOV, MG TI H-INFINITY SYNTHESIS USING A BILINEAR POLE SHIFTING TRANSFORM SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB An H(infinity) control law design is presented for a benchmark problem consisting of an undamped pair of spring-coupled masses with a sensor and actuator that are not collocated. This simple mechanical system captures many of the salient features of more complex aircraft and space structure vibration control problems. The H(infinity) problem formulation enables the issue of stability robustness in the face of large mass and spring constant variation to be directly addressed. Constraints on closed-loop dominant pole locations and settling time are accommodated via a simple s-plane bilinear transform. The transform parameter can give direct control of closed-loop disturbance settling time and controller open-loop pole-zero locations. A four-state H(infinity) minimum phase controller was found to meet the given specifications of each design. Detailed analysis on the tradeoffs of sensor noise vs control energy are also presented. C1 UNIV SO CALIF,DEPT ELECT ENGN,LOS ANGELES,CA 90089. RP CHIANG, RY (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 15 TC 15 Z9 18 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1111 EP 1117 DI 10.2514/3.20957 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500010 ER PT J AU WANG, YJ SHIEH, LS SUNKEL, JW AF WANG, YJ SHIEH, LS SUNKEL, JW TI OBSERVER-BASED ROBUST-H-INFINITY CONTROL LAWS FOR UNCERTAIN LINEAR-SYSTEMS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID RICCATI EQUATION APPROACH; STABILIZING CONTROLLERS; STATE-FEEDBACK; DESIGN AB Based on the algebraic Riccati equation approach, this paper presents a simple, flexible method for designing full-order observer-based robust-H(infinity) control laws for linear systems with structured parameter uncertainty. The observer-based robust-H(infinity) output-feedback control law, obtained by solving three augmented algebraic Riccati equations, provides both robust stability and disturbance attenuation with H(infinity)-norm bound for the closed-loop uncertain linear system. Several tuning parameters are embedded into the augmented algebraic Riccati equations so that flexibility in finding the symmetric positive-definite solutions (and hence the robust-H(infinity) control laws) is significantly increased. A benchmark problem associated with a mass-spring system, which approximates the dynamics of a flexible structure, is used to illustrate the design methodologies, and simulation results are presented. C1 NASA,LYNDON B JOHNSON SPACE CTR,DIV NAVIGAT CONTROL & AERONAUT,HOUSTON,TX 77058. RP WANG, YJ (reprint author), UNIV HOUSTON,DEPT ELECT ENGN,HOUSTON,TX 77204, USA. NR 20 TC 9 Z9 10 U1 1 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1125 EP 1133 DI 10.2514/3.20959 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500012 ER PT J AU MUSGRAVE, JL AF MUSGRAVE, JL TI LINEAR QUADRATIC SERVO CONTROL OF A REUSABLE ROCKET ENGINE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID GENERAL SERVOMECHANISM PROBLEM; ROBUST CONTROL; DESIGN AB This work develops a new design method for the servo compensator in the frequency domain using singular value inequalities and applies the method to a reusable rocket engine. The servo compensator allows command following with set point control that is necessary for engine throttling during downthrust maneuvers. A Kalman filter reconstructs the engine state vector and loop transfer recovery recovers the required degree of robustness while maintaining satisfactory rejection of sensor noise from the command error. The approach is applied to the design of a linear controller for a reusable rocket engine satisfying performance constraints in the frequency domain. Simulation results demonstrate the performance of the linear control design on a nonlinear rocket engine model over power levels typical of mainstage operation. RP MUSGRAVE, JL (reprint author), NASA,LEWIS RES CTR,ADV CONTROL TECHNOL BRANCH,MS 77-1,CLEVELAND,OH 44135, USA. NR 11 TC 1 Z9 1 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1149 EP 1154 DI 10.2514/3.20962 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500015 ER PT J AU CHEN, GS LURIE, BJ AF CHEN, GS LURIE, BJ TI ACTIVE MEMBER BRIDGE FEEDBACK-CONTROL FOR DAMPING AUGMENTATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB An active damping augmentation approach using active members in a structural system is described. The problem of maximizing the vibration damping in a lightly damped structural system is considered using the analogy of impedance matching between the load and source impedances in an electrical network. The proposed active damping augmentation approach therefore consists of finding the desired active member impedances that maximize the vibration damping, and designing a feedback control in order to achieve desired active member impedances. This study uses a bridge feedback concept that feeds back a combination of signals from sensors of the axial force and relative velocity across the active member to realize the desired active member impedance. The proposed active damping augmentation approach and bridge feedback concept were demonstrated on a three-longeron softly suspended truss structure. RP CHEN, GS (reprint author), JET PROP LAB,APPL MECH TECHNOL SECT,MAIL STOP 157-316,PASADENA,CA 91109, USA. NR 15 TC 4 Z9 4 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1155 EP 1160 DI 10.2514/3.20963 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500016 ER PT J AU JUANG, JN PHAN, M AF JUANG, JN PHAN, M TI ROBUST CONTROLLER DESIGNS FOR 2ND-ORDER DYNAMIC-SYSTEMS - A VIRTUAL PASSIVE APPROACH SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper presents a robust controller design for second-order dynamic systems. The controller is model independent and is a virtual second-order dynamic system. The conditions for actuator and sensor placements are identified for controller designs that guarantee overall closed-loop stability. The dynamic controller can be viewed as a virtual passive damping system that serves to stabilize the actual dynamic system. The control gains are interpreted as virtual mass, spring, and dashpot elements that play the same roles as actual physical elements in stability analysis. Position, velocity, and acceleration feedback are considered. Simple examples are provided to illustrate the controller design. From this illustration the physical meaning of the controller design is apparent. RP JUANG, JN (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 3 TC 53 Z9 53 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1192 EP 1198 DI 10.2514/3.20968 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500021 ER PT J AU BRUNER, AM BELVIN, WK HORTA, LG JUANG, JN AF BRUNER, AM BELVIN, WK HORTA, LG JUANG, JN TI ACTIVE VIBRATION ABSORBER FOR THE CSI EVOLUTIONARY MODEL - DESIGN AND EXPERIMENTAL RESULTS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB The development of control technology for large flexible structures must include practical demonstrations to aid in the understanding of controlled structures in space. To support this effort, a testbed facility has been developed to study practical implementation of new control technologies. The paper discusses the design of a second-order acceleration feedback controller that acts as an active vibration absorber. This controller provides guaranteed stability margins for collocated accelerometer/actuator pairs in the absence of accelerometer/actuator dynamics and computational time delay. Experimental results in the presence of these factors are presented and discussed. The primary performance objective considered is damping augmentation of the first nine structural modes. Comparison of experimental and predicted closed-loop damping is presented, including test and simulated-time histories for open- and closed-loop cases. Although the simulation and test results are not in full agreement, robustness of this design under model uncertainly is demonstrated. The basic advantage of this second-order controller design is that the stability of the controller is model-independent for collocated accelerometers and actuators. C1 NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665. RP BRUNER, AM (reprint author), LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666, USA. NR 7 TC 23 Z9 23 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1253 EP 1257 DI 10.2514/3.20976 PG 5 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500029 ER PT J AU SKELTON, RE HANKS, BR SMITH, M AF SKELTON, RE HANKS, BR SMITH, M TI STRUCTURE REDESIGN FOR IMPROVED DYNAMIC-RESPONSE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID CONTROLLERS; SYSTEMS AB The concepts of multivariable control design are used to redesign structures represented by lumped parameter models. When the moss is held constant, the changing of passive structural members is mathematically equivalent to an output feedback decentralized control problem. When the mass is also allowed to change, a generalization of the output feedback formulation is required. The design objective is to minimize the changes in the structure required to simultaneously satisfy inequality constraints on both the root-mean-square and absolute value of the dynamic response of each output. An alternative objective treated is to minimize the root-mean-square of the dynamic response subject to inequality constraints on the changes allowed in each structural member. Examples illustrate both procedures. C1 NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665. RP SKELTON, RE (reprint author), PURDUE UNIV,SCH AERONAUT & ASTRONAUT,W LAFAYETTE,IN 47907, USA. NR 19 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1272 EP 1278 DI 10.2514/3.20979 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500032 ER PT J AU GAWRONSKI, W MELLSTROM, JA AF GAWRONSKI, W MELLSTROM, JA TI MODEL-REDUCTION FOR SYSTEMS WITH INTEGRATORS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note RP GAWRONSKI, W (reprint author), JET PROP LAB,GROUND ANTENNAS SECT,PASADENA,CA 91109, USA. NR 2 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1304 EP 1306 DI 10.2514/3.20990 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500043 ER PT J AU WU, SC BERTIGER, WI WU, JT AF WU, SC BERTIGER, WI WU, JT TI MINIMIZING SELECTIVE AVAILABILITY ERROR ON SATELLITE AND GROUND GLOBAL POSITIONING SYSTEM MEASUREMENTS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note RP WU, SC (reprint author), JET PROP LAB,TRACKING SYST & APPLICAT SECT,PASADENA,CA 91109, USA. NR 5 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1306 EP 1309 DI 10.2514/3.20991 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500044 ER PT J AU PAIELLI, RA AF PAIELLI, RA TI GLOBAL TRANSFORMATION OF ROTATION MATRICES TO EULER PARAMETERS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note RP PAIELLI, RA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 6 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1992 VL 15 IS 5 BP 1309 EP 1311 DI 10.2514/3.20992 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA JM285 UT WOS:A1992JM28500045 ER PT J AU BECK, LR AF BECK, LR TI SPECIAL SECTION - EARTH SYSTEM SCIENCE RESEARCH, NASA AMES RESEARCH-CENTER CONTRIBUTIONS SO JOURNAL OF IMAGING SCIENCE AND TECHNOLOGY LA English DT Editorial Material RP BECK, LR (reprint author), NASA,AMES RES CTR,TGS TECHNOL INC,MOFFETT FIELD,CA 94035, USA. RI Wright, Dawn/A-4518-2011 OI Wright, Dawn/0000-0002-2997-7611 NR 2 TC 1 Z9 1 U1 0 U2 0 PU I S & T - SOC IMAGING SCIENCE TECHNOLOGY PI SPRINGFIELD PA 7003 KILWORTH LANE, SPRINGFIELD, VA 22151 SN 8750-9237 J9 J IMAGING SCI TECHN JI J. Imaging Sci. Technol. PD SEP-OCT PY 1992 VL 36 IS 5 BP 416 EP 416 PG 1 WC Imaging Science & Photographic Technology SC Imaging Science & Photographic Technology GA JR474 UT WOS:A1992JR47400002 ER PT J AU HAMMER, PD VALERO, FPJ PETERSON, DL SMITH, WH AF HAMMER, PD VALERO, FPJ PETERSON, DL SMITH, WH TI REMOTE-SENSING OF EARTHS ATMOSPHERE AND SURFACE USING A DIGITAL ARRAY SCANNED INTERFEROMETER - A NEW TYPE OF IMAGING SPECTROMETER SO JOURNAL OF IMAGING SCIENCE AND TECHNOLOGY LA English DT Article ID FOURIER-TRANSFORM SPECTROMETER; SPECTROSCOPY; FIRE; AIRCRAFT AB The remote sensing of Earth's radiative fields at visible and infrared wavelengths by imaging spectrometers is an important means of probing the structure and constituents of the atmosphere and surface In this study we discuss the potentials of the digital array scanned interferometer (DASI). DASIs have many of the positive characteristics associated with Fourier transform spectrometers and also the capability of spatial mapping/imaging. Thus a DASI has the potential of achieving higher spectral and spatial resolution at a specified signal-to-noise level than do equivalent aperture grating-based instruments. One of the most notable features of DASIs is their ability to acquire an entire interferogram simultaneously without any moving optical elements. The simplicity of design and operation of DASIs makes them particularly suitable candidates for both ground- and airborne platform-based remote sensing instruments. C1 WASHINGTON UNIV,ST LOUIS,MO 63130. RP HAMMER, PD (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 26 TC 5 Z9 5 U1 1 U2 2 PU I S & T - SOC IMAGING SCIENCE TECHNOLOGY PI SPRINGFIELD PA 7003 KILWORTH LANE, SPRINGFIELD, VA 22151 SN 8750-9237 J9 J IMAGING SCI TECHN JI J. Imaging Sci. Technol. PD SEP-OCT PY 1992 VL 36 IS 5 BP 417 EP 422 PG 6 WC Imaging Science & Photographic Technology SC Imaging Science & Photographic Technology GA JR474 UT WOS:A1992JR47400003 ER PT J AU WRIGLEY, RC SLYE, RE KLOOSTER, SA FREEDMAN, RS CARLE, M MCGREGOR, LF AF WRIGLEY, RC SLYE, RE KLOOSTER, SA FREEDMAN, RS CARLE, M MCGREGOR, LF TI THE AIRBORNE OCEAN COLOR IMAGER - SYSTEM DESCRIPTION AND IMAGE-PROCESSING SO JOURNAL OF IMAGING SCIENCE AND TECHNOLOGY LA English DT Article ID SCANNER; SEA AB The Airborne Ocean Color Imager was developed as an aircraft instrument to simulate the spectral and radiometric characteristics of the next generation of satellite ocean color instrumentation. Data processing programs have been developed as extensions of the Coastal Zone Color Scanner algorithms for atmospheric correction and bio-optical output products. The latter include several bio-optical algorithms for estimating phytoplankton pigment concentration, as well as one for the diffuse attenuation coefficient of the water. Additional programs have been developed to geolocate these products and remap them into a georeferenced data base, using data from the aircraft's inertial navigation system. Examples illustrate the sequential data products generated by the processing system, using data from flightlines near the mouth of the Mississippi River: from raw data to atmospherically corrected data, to bio-optical data, to geolocated data, and, finally, to georeferenced data. C1 NASA,AMES RES CTR,STERLING FED SYST,MOFFETT FIELD,CA 94035. SPECTRO SCAN INC,CORAL GABLES,FL 33146. LOCKHEED ENGN & SCI CO,BAY ST LOUIS,MS 39529. RP WRIGLEY, RC (reprint author), NASA,AMES RES CTR,TGS TECHNOL INC,MOFFETT FIELD,CA 94035, USA. NR 13 TC 3 Z9 3 U1 0 U2 0 PU I S & T - SOC IMAGING SCIENCE TECHNOLOGY PI SPRINGFIELD PA 7003 KILWORTH LANE, SPRINGFIELD, VA 22151 SN 8750-9237 J9 J IMAGING SCI TECHN JI J. Imaging Sci. Technol. PD SEP-OCT PY 1992 VL 36 IS 5 BP 423 EP 430 PG 8 WC Imaging Science & Photographic Technology SC Imaging Science & Photographic Technology GA JR474 UT WOS:A1992JR47400004 ER PT J AU WOOD, BL BECK, LR LAWLESS, JG VESECKY, JF AF WOOD, BL BECK, LR LAWLESS, JG VESECKY, JF TI PRELIMINARY CONSIDERATIONS FOR A SMALL SATELLITE TO MONITOR ENVIRONMENTAL-CHANGE ASSOCIATED WITH VECTOR-BORNE DISEASE SO JOURNAL OF IMAGING SCIENCE AND TECHNOLOGY LA English DT Article ID POPULATION; HABITATS; MODEL AB During the International Space Year in 1992, scientists, teachers, and students will exploit the global perspective provided by Earth-observing satellites to understand better global environmental change and how it will affect humanity's future. One of the most dramatic expressions of environmental change can be seen in the patterns of human health and disease. To monitor and predict the human health consequences of environmental change, a growing segment of the public health community is advocating the use of satellite imagery to monitor environmental parameters that influence the spatial and temporal patterns of vector-borne diseases. It is anticipated that a dedicated remote sensing surveillance capability will lead to the development of a "disease early warning system" for identifying areas of high disease transmission risk and directing control measures. For malaria, an example relevant to many other vector-borne diseases, key environmental parameters include the spatial and temporal patterns of vegetation type and condition, land use, standing water, and human settlements. Analysis of data from existing satellite systems [e.g., Landsat and France's Systeme Pour l'Observation de la Terre (SPOT)], suggests both potential opportunities and shortcomings in the ability to monitor these parameters in malarial areas by using remote sensing data. The shortcomings of current operational systems, including timeliness, lack of rapid accessibility to data, and spatial and temporal resolution, have stimulated interest in developing a satellite system designed to focus exclusively on the public health needs associated with surveillance of vector-borne diseases. A preliminary set of design requirements for a remote sensing satellite dedicated to monitoring environmental parameters that influence the patterns of vector-borne diseases is presented in this study. Also, a preliminary student engineering design for a satellite platform is presented and reviewed. The goal of this remote sensing system would be to provide near-real-time data acquisition and processing to public health users at a number of sites where malaria or other vector-borne diseases are significant human health problems. The International Space Year provides an excellent forum in which to pursue discussions among public health investigators, remote sensing scientists, and aerospace engineers toward defining the technical design requirements for a system, including satellite platform, sensor characteristics, communications, and ground infrastructure. C1 UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. RP WOOD, BL (reprint author), NASA,AMES RES CTR,TGS TECHNOL INC,MOFFETT FIELD,CA 94035, USA. NR 35 TC 5 Z9 5 U1 0 U2 0 PU I S & T - SOC IMAGING SCIENCE TECHNOLOGY PI SPRINGFIELD PA 7003 KILWORTH LANE, SPRINGFIELD, VA 22151 SN 8750-9237 J9 J IMAGING SCI TECHN JI J. Imaging Sci. Technol. PD SEP-OCT PY 1992 VL 36 IS 5 BP 431 EP 439 PG 9 WC Imaging Science & Photographic Technology SC Imaging Science & Photographic Technology GA JR474 UT WOS:A1992JR47400005 ER PT J AU HLAVKA, CA STRONG, LL AF HLAVKA, CA STRONG, LL TI ASSESSING DEFORESTATION AND HABITAT FRAGMENTATION IN UGANDA USING SATELLITE-OBSERVATIONS AND FRACTAL ANALYSIS SO JOURNAL OF IMAGING SCIENCE AND TECHNOLOGY LA English DT Article AB Landsat Multispectral Scanner, Systeme Pour l'Observation de la Te-e (SPOT) multispectral mode, and Advanced Very High Resolution Radiometer (AVHRR) Local Area Coverage imagery of Ugandan forests were analyzed for assessment of the information content related to deforestation and tropical habitat fragmentation. Landsat multispectral scanner imagery of the Kibale and Mabira Forests in Uganda was processed to produce digital land cover maps for 1973 and 1988. Measurements on the digital maps produced estimates of forest clearing and regrowth, edge-to-area ratios, and disturbance in the study area for the 15-year period. Analysis of actual and simulated AVHRR imagery indicated that it might be possible to monitor major changes in forest extent with the relatively coarse spatial resolution of AVHRR imagery (approximately 1 km), if ancillary data, such as high-resolution imagery over sample areas, were available. The fractal dimension (D) of the forest edges, measured with the Landsat and SPOT imagery, was consistently approximately 1.7 or 1.8. This high fractal dimension, much higher than D = 1.0 for straight lines, was caused by the complex pattern of clearings, remnant forest stands, and jagged forest edges made by repeated human encroachment over centuries. A fractal dimension greater than 1.0 implies that edge-to-area ratios are a function of the scale used for measurement. When D is known, it can be used to adjust measures involving edge length to a selected scale (e.g., to enable comparisons among data from various sources or to adjust measurements made at a coarse scale, such as that of AVHRR) to finer scales that are of interest to ecologists and biologists. RP HLAVKA, CA (reprint author), NASA,AMES RES CTR,TGS TECHNOL INC,MAIL STOP 242-4,MOFFETT FIELD,CA 94035, USA. NR 29 TC 1 Z9 1 U1 0 U2 1 PU I S & T - SOC IMAGING SCIENCE TECHNOLOGY PI SPRINGFIELD PA 7003 KILWORTH LANE, SPRINGFIELD, VA 22151 SN 8750-9237 J9 J IMAGING SCI TECHN JI J. Imaging Sci. Technol. PD SEP-OCT PY 1992 VL 36 IS 5 BP 440 EP 445 PG 6 WC Imaging Science & Photographic Technology SC Imaging Science & Photographic Technology GA JR474 UT WOS:A1992JR47400006 ER PT J AU PETERSON, DL HUBBARD, GS AF PETERSON, DL HUBBARD, GS TI SCIENTIFIC ISSUES AND POTENTIAL REMOTE-SENSING REQUIREMENTS FOR PLANT BIOCHEMICAL CONTENT SO JOURNAL OF IMAGING SCIENCE AND TECHNOLOGY LA English DT Article ID INFRARED REFLECTANCE SPECTROSCOPY; CANOPY CHEMISTRY; LEAF CHEMISTRY; FOREST CANOPY; NITROGEN; NOISE; LIGHT AB Application of developments in imaging spectrometry to the study of terrestrial ecosystems, which began in 1983, demonstrate the potential to estimate lignin and nitrogen concentrations of plant canopies by remote-sensing techniques. These two key biochemical components are among chemical composition properties of leaves and canopies useful to remote-sensing studies of biogeochemical cycling in terrestrial ecosystems. Estimation of these parameters from the first principles of radiative transfer and the interactions of light with plant materials is not presently possible, principally because of lack of knowledge about internal leaf scattering and specific absorption involving biochemical compounds. Although a statistical foundation relating biochemical concentration to plant reflectance is growing, a firm base for developing a theoretical understanding is not yet available. From the perspective of remote-sensing instrumentation, sensors are needed to support derivative imaging spectroscopy. Biochemical absorption features tend to occur in functional groupings throughout the 1100- to 2500-nm region. Derivative spectroscopy improves the information associated with the weaker, narrower absorption features of biochemical absorption that are superimposed on the strong absolute variations due to foliar biomass, pigments, and leaf water content of plant canopies. Preliminary sensor specifications call for 8-nm band-widths at 2-nm centers in four spectral regions (about 400 bands total) and a signal-to-noise performance of at least 1000:1 for 20% albedo targets in the 2000-nm region. RP PETERSON, DL (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 47 TC 36 Z9 39 U1 0 U2 10 PU I S & T - SOC IMAGING SCIENCE TECHNOLOGY PI SPRINGFIELD PA 7003 KILWORTH LANE, SPRINGFIELD, VA 22151 SN 8750-9237 J9 J IMAGING SCI TECHN JI J. Imaging Sci. Technol. PD SEP-OCT PY 1992 VL 36 IS 5 BP 446 EP 456 PG 11 WC Imaging Science & Photographic Technology SC Imaging Science & Photographic Technology GA JR474 UT WOS:A1992JR47400007 ER PT J AU MARDER, SR PERRY, JW SCHAEFER, WP AF MARDER, SR PERRY, JW SCHAEFER, WP TI 4-N-METHYLSTILBAZOLIUM TOLUENE-PARA-SULFONATE SALTS WITH LARGE 2ND-ORDER OPTICAL NONLINEARITIES SO JOURNAL OF MATERIALS CHEMISTRY LA English DT Note DE 2ND-HARMONIC GENERATION; ORGANIC CRYSTALS; NONLINEAR OPTICAL MATERIAL; STILBAZOLIUM SALT ID CRYSTAL-STRUCTURE; NONLINEARITIES AB Donor-substituted 4-N-methylstilbazolium toluene-p-sulfonate salts and related salts containing cations with extended conjugation exhibit an unusually high propensity to crystallize in non-centrosymmetric space groups. The new compound 3',4'-dihydroxy-4-N-methylstilbazolium toluene-p-sulfonate crystallizes in the space group P1 and exhibits a powder second-harmonic generation efficiency 106 times that of urea measured at 1.907-mu-m. C1 CALTECH,BECKMAN INST,PASADENA,CA 91125. RP MARDER, SR (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 19 TC 35 Z9 35 U1 0 U2 3 PU ROYAL SOC CHEMISTRY PI CAMBRIDGE PA THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON ROAD, CAMBRIDGE, CAMBS, ENGLAND CB4 4WF SN 0959-9428 J9 J MATER CHEM JI J. Mater. Chem. PD SEP PY 1992 VL 2 IS 9 BP 985 EP 986 DI 10.1039/jm9920200985 PG 2 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA JN406 UT WOS:A1992JN40600016 ER PT J AU SINHA, MP GUTNIKOV, G AF SINHA, MP GUTNIKOV, G TI ROLE OF A MICROBORE CAPILLARY COLUMN IN THE DEVELOPMENT OF A PORTABLE GAS-CHROMATOGRAPHY MASS-SPECTROMETER SO JOURNAL OF MICROCOLUMN SEPARATIONS LA English DT Article; Proceedings Paper CT 14TH INTERNATIONAL SYMP ON CAPILLARY CHROMATOGRAPHY CY MAY, 1992 CL BALTIMORE, MD DE MICROBORE CAPILLARY COLUMN; PORTABLE MASS SPECTROGRAPH; ARRAY DETECTOR; TIME-RESOLVED MEASUREMENTS; GAS-CHROMATOGRAPHY MASS-SPECTROMETRY ID INCREASED SPEED; ARRAY DETECTOR; SYSTEMS AB For the development of a portable gas chromatograph-mass spectrometer (GC-MS) system, drastic reduction in the carrier gas load is necessary in order to minimize the pumping requirements of the mass spectrometer. Two approaches were investigated for achieving this. The first involved the use of a palladium-hydrogen interface and was found not to be viable due to its chemical reactivity. The second utilized a short microbore capillary column (3-m x 50-mum i.d.). The small cross-sectional area of the column reduced the gas load into the MS and yielded sharp chromatographic peaks possessing full-widths at half-height in the range of 200-600 ms from a mixture of priority pollutants. Good column efficiency ( > 2.3 x 10(4) theoretical plates/meter for k of 10) and resolution were observed, and analyses were completed within a few minutes. Mass spectral measurements were performed with a miniaturized focal plane mass spectrograph having an integrating array detector. Because this system detects (integrates) ions of all masses simultaneously and continuously, short data acquisition times can be used to measure several spectra per gas chromatographic peak without loss in sensitivity. Such time-resolved mass spectral measurements were applied to the separation and identification of benzene and carbon tetrachloride which coeluted from the column. Our results show that a short microbore capillary column in conjunction with a miniaturized mass spectrograph and an array detector is eminently suited for the development of a field portable GC-MS system of high performance. C1 CALIF STATE POLYTECH UNIV POMONA,DEPT CHEM,POMONA,CA 91768. RP SINHA, MP (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 22 TC 7 Z9 7 U1 1 U2 2 PU MICROSEPARATIONS INC PI PROVO PA DEPT CHEM BRIGHAM YOUNG UNIV, PROVO, UT 84602-1022 SN 1040-7685 J9 J MICROCOLUMN SEP JI J. Microcolumn Sep. PD SEP-OCT PY 1992 VL 4 IS 5 BP 405 EP 410 DI 10.1002/mcs.1220040507 PG 6 WC Chemistry, Analytical SC Chemistry GA JX484 UT WOS:A1992JX48400005 ER PT J AU SEASHOLTZ, RG ZUPANC, FJ SCHNEIDER, SJ AF SEASHOLTZ, RG ZUPANC, FJ SCHNEIDER, SJ TI SPECTRALLY RESOLVED RAYLEIGH-SCATTERING DIAGNOSTIC FOR HYDROGEN OXYGEN ROCKET PLUME STUDIES SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT 29TH MEETING ON AEROSPACE SCIENCES CY JAN 07-10, 1991 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT ID TEMPERATURE; DENSITY AB A Rayleigh scattering diagnostic has been developed to measure gas density, temperature, and velocity in the exhaust plume of 100 N thrust class hydrogen-Oxygen rockets. The spectrum of argon-ion laser light scattered by the gas molecules in the plume (predominantly water vapor) is measured with a scanning Fabry-Perot interferometer. The gas density is determined from the total scattered power, the gas temperature from the spectral width, and the velocity from the shift in the peak of the spectrum from the frequency of the incident laser light. The diagnostic has been demonstrated in a rocket test cell and a discussion of results is given. C1 NASA,LEWIS RES CTR,LOW THRUST PROPULS BRANCH,CLEVELAND,OH 44135. RP SEASHOLTZ, RG (reprint author), NASA,LEWIS RES CTR,OPT MEASUREMENT SYST BRANCH,CLEVELAND,OH 44135, USA. NR 17 TC 16 Z9 17 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 SEP-OCT PY 1992 VL 8 IS 5 BP 935 EP 942 DI 10.2514/3.23575 PG 8 WC Engineering, Aerospace SC Engineering GA JM028 UT WOS:A1992JM02800003 ER PT J AU VALENTI, EL AF VALENTI, EL TI ELECTRIC-FIELD AND RADIO-FREQUENCY MEASUREMENTS FOR ROCKET ENGINE HEALTH MONITORING APPLICATIONS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Widespread efforts are being conducted toward development of real-time health-monitoring systems for the Space Shuttle main engine (SSME). Electric field (EF) and radio frequency (RF) emissions generated in the exhaust plumes of the diagnostic testbed facility thruster (DTFT) and the SSME on the A-1 test stand at the John C. Stennis Space Center have been examined briefly for potential applications to plume diagnostics and engine health monitoring. The exhaust plume of the SSME (and DTFT) is a high-velocity, cool plasma with ions accelerating at various rates. The exhaust produces electromagnetic radiation, whose temporal and spatial characteristics vary with engine operating parameters. Hypothetically, anomalous engine conditions could produce measurable changes in any characteristic EF and RF spectral signatures identifiable with a "healthy" plume. Tests to determine the presence of EF and RF emissions in the DTFT and SSME exhaust plumes were conducted. EF and RF emissions were detected using state-of-the-art sensors. Analysis of limited data sets show some apparent consistencies in spectral signatures. Significant emissions increases were detected during controlled tests using dopants injected into the DTFT. The small data sets obtained were qualitative but not conclusive. Further data collection is required to establish repeatability and to identify emission sources accurately. RP VALENTI, EL (reprint author), SVERDRUP TECHNOL INC,STENNIS SPACE CTR,DEPT ENGN & SCI,TECHNOL DEV SECT,MISSISSIPI,MS 39529, USA. NR 2 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1992 VL 8 IS 5 BP 943 EP 947 DI 10.2514/3.23576 PG 5 WC Engineering, Aerospace SC Engineering GA JM028 UT WOS:A1992JM02800004 ER PT J AU KORTE, JJ KUMAR, A SINGH, DJ GROSSMAN, B AF KORTE, JJ KUMAR, A SINGH, DJ GROSSMAN, B TI LEAST-SQUARES PARABOLIZED NAVIER-STOKES PROCEDURE FOR OPTIMIZING HYPERSONIC WIND-TUNNEL NOZZLES SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A new procedure is demonstrated for optimizing hypersonic wind-tunnel nozzle contours. The procedure couples a computational fluid dynamics (CFD) computer code to an optimization algorithm, and is applied to both conical and contoured hypersonic nozzles for the purpose of determining an optimal set of parameters to describe the surface geometry. A design objective function is specified based on the deviation from the desired test section flowfield conditions. The objective function is minimized by optimizing the parameters used to describe the nozzle contour based on the solution to a nonlinear least-squares problem. The effect of the changes in the nozzle wall parameters are evaluated by computing the nozzle flow using the parabolized Navier-Stokes equations. The advantage of the new procedure is that it directly takes into account the displacement effect of the boundary layer on the wall contour. The new procedure provides a method for optimizing hypersonic nozzles of high Mach numbers that have been designed by classical procedurs, but are shown to produce poor flow quality due to the large boundary layers present in the test section. The procedure is demonstrated by finding the optimum design parameters for a Mach 10 conical nozzle and a Mach 6 and Mach 15 contoured nozzle. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. VIRGINIA POLYTECH INST & STATE UNIV,DEPT AEROSP & OCEAN ENGN,BLACKSBURG,VA 24061. RP KORTE, JJ (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665, USA. NR 10 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1992 VL 8 IS 5 BP 1057 EP 1063 DI 10.2514/3.23592 PG 7 WC Engineering, Aerospace SC Engineering GA JM028 UT WOS:A1992JM02800020 ER PT J AU RANGWALLA, AA MADAVAN, NK JOHNSON, PD AF RANGWALLA, AA MADAVAN, NK JOHNSON, PD TI APPLICATION OF AN UNSTEADY NAVIER-STOKES SOLVER TO TRANSONIC TURBINE DESIGN SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID ROTOR-STATOR INTERACTION; SIMULATIONS; FLOW; TURBOMACHINERY; EQUATIONS AB This study presents a numerical evaluation of the performance of the first stage of a new-generation turbine design. The numerical method solves the two-dimensional, thin-layer, Navier-Stokes equations using a system of patched grids. Three-dimensional effects of stream-tube contraction are also modeled. The study focuses on the effects of axial gap variation on the unsteady rotor-stator interactions and on stage performance. Results are presented for three different axial gaps. The results indicate that the unsteady interactions can be very large in this design. These interactions affect not only the stage efficiency but also substantially alter the time-averaged features of the flow. In particular, for the case of the smallest axial gap, it was found that there was an unsteady shock on the stator suction surface which spanned the gap region and impinged upon the moving rotor airfoils. An increase in the axial gap resulted in a shock-free flow and a performance level that was close to that expected by the designer. C1 PRATT & WHITNEY AIRCRAFT,TURBINE AERODYNAM,W PALM BEACH,FL 33410. RP RANGWALLA, AA (reprint author), NASA,STERLING FED SYST,MOFFETT FIELD,CA 94035, USA. NR 13 TC 9 Z9 10 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 SEP-OCT PY 1992 VL 8 IS 5 BP 1079 EP 1086 DI 10.2514/3.23595 PG 8 WC Engineering, Aerospace SC Engineering GA JM028 UT WOS:A1992JM02800023 ER PT J AU COLVIN, J SCHALLHORN, P RAMOHALLI, K AF COLVIN, J SCHALLHORN, P RAMOHALLI, K TI FULL SYSTEM ENGINEERING DESIGN AND OPERATION OF AN OXYGEN PLANT SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB This paper describes one area of a project whose general aim is to produce oxygen from the indigenous resources on Mars. After discussing briefly the project's background and the experimental system design, specific experimental results of the electrolytic cell are presented. At the heart of the oxygen production system is a tubular solid zirconia electrolyte cell that will electrochemically separate oxygen from a high-temperature stream of Coleman grade carbon dioxide. Experimental results are discussed and certain system efficiencies are defined. The parameters varied include 1) the cell operating temperature; 2) the carbon dioxide flow rate; and 3) the voltage applied across the cell. The results confirm our theoretical expectations. RP COLVIN, J (reprint author), UNIV ARIZONA,NASA,SPACE ENGN RES CTR,TUCSON,AZ 85712, USA. NR 10 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1992 VL 8 IS 5 BP 1103 EP 1108 DI 10.2514/3.23598 PG 6 WC Engineering, Aerospace SC Engineering GA JM028 UT WOS:A1992JM02800026 ER PT J AU KRATZ, DP VARANASI, P AF KRATZ, DP VARANASI, P TI A REEXAMINATION OF THE GREENHOUSE-EFFECT DUE TO CFC-11 AND CFC-12 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID TRACE GASES; CONTINUUM ABSORPTION; GLOBAL CLIMATE; WATER-VAPOR; CHLOROFLUOROCARBONS; STRATOSPHERE; INTENSITIES; CF2CL2; MODEL; CFCL3 AB Employing the most recent laboratory absorption-coefficient data1 on the thermal infrared (i.r.) bands of CFC-11 (CFCl3) and CFC-12 (CF2Cl2), which were measured at several temperatures relevant to the troposphere and the stratosphere, the greenhouse effect produced by these two CFCs has been reexamined. The effect upon the atmospheric radiative fluxes due to the temperature dependence of the absorption coefficient, especially in the many hot bands present in this spectral region, has been studied. The validity of the often used optically-thin approximation has been scrutinized in view of the observed enhancement in the absorption by the CFCs at low temperatures. The influence of absorption by water vapor on the radiative transfer through columns of CFC-11 and CFC-12 has also been considered. It has been shown that, even though each of these individual refinements may modify the previously estimated effect due to the CFCs by a small amount only, the collective effect may be a non-negligible 35% change in the surface-troposphere heating for every ppbv of CFC-11 and CFC-12 each introduced into a model atmosphere. C1 SUNY STONY BROOK,INST TERR & PLANETARY ATMOSPHER,STONY BROOK,NY 11794. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHER LAB,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. NR 42 TC 14 Z9 14 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD SEP PY 1992 VL 48 IS 3 BP 245 EP 254 DI 10.1016/0022-4073(92)90014-U PG 10 WC Optics; Spectroscopy SC Optics; Spectroscopy GA JK562 UT WOS:A1992JK56200002 ER PT J AU GANAPOL, BD MYNENI, RB AF GANAPOL, BD MYNENI, RB TI THE APPLICATION OF THE PRINCIPLES OF INVARIANCE TO THE RADIATIVE-TRANSFER EQUATION IN PLANT CANOPIES SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article AB Solutions of the radiative transfer equation describing photon interactions with vegetation canopies are important in remote sensing since they provide the canopy reflectance distribution required in the interpretation of satellite acquired information. The general one-dimensional two-angle transport problem for a finite copy of arbitrary leaf angle distribution is considered. Analytical solutions are obtained in terms of generalized Chandrasekhar's X- and Y-functions by invoking the principles of invariance. A critical step in the formulation involves the decomposition of the integral of the scattering phase function into a product of known functions of the incident and scattered photon directions. Several simplified cases previously considered in the literature are derived from the generalized solution. Various symmetries obeyed by the scattering operator and reciprocity relations are formally proved. C1 UNIV ARIZONA,DEPT NUCL & ENERGY ENGN,TUCSON,AZ 85721. RP GANAPOL, BD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,MAIL CODE 974,GREENBELT,MD 20771, USA. RI Myneni, Ranga/F-5129-2012 NR 10 TC 9 Z9 9 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD SEP PY 1992 VL 48 IS 3 BP 321 EP 339 DI 10.1016/0022-4073(92)90022-V PG 19 WC Optics; Spectroscopy SC Optics; Spectroscopy GA JK562 UT WOS:A1992JK56200010 ER PT J AU ATKINSON, S GILMARTIN, WG AF ATKINSON, S GILMARTIN, WG TI SEASONAL TESTOSTERONE PATTERN IN HAWAIIAN MONK SEALS (MONACHUS-SCHAUINSLANDI) SO JOURNAL OF REPRODUCTION AND FERTILITY LA English DT Article DE HAWAIIAN MONK SEAL; TESTOSTERONE; SEASONAL BREEDING ID EVOLUTION AB Blood samples from four captive male Hawaiian monk seals were collected at intervals of one month for one year for testosterone assay. Plasma testosterone concentrations, measured by radioimmunoassay, revealed a clear seasonal pattern. The lowest mean testosterone concentration (0.09 +/- 0.04 ng ml-1) occurred in January, and the highest (1.78 +/- 0.40 ng ml-1) in June. The seasonal occurrence of births and of injuries related to mating in wild populations of Hawaiian monk seals showed a distinct association with the period of high testosterone. This study supports other data that indicate that the Hawaiian monk seal is a seasonal breeder and is reproductively active for longer than monachine seals that live in higher latitudes. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. RP ATKINSON, S (reprint author), UNIV HAWAII,HAWAII INST MARINE BIOL,1000 POPE RD,MARINE SCI BLDG 212,HONOLULU,HI 96822, USA. NR 16 TC 25 Z9 25 U1 0 U2 3 PU J REPROD FERTIL INC PI CAMBRIDGE PA 22 NEWMARKET RD, CAMBRIDGE, ENGLAND CB5 8DT SN 0022-4251 J9 J REPROD FERTIL JI J. Reprod. Fertil. PD SEP PY 1992 VL 96 IS 1 BP 35 EP 39 PG 5 WC Reproductive Biology SC Reproductive Biology GA JT472 UT WOS:A1992JT47200004 PM 1432968 ER PT J AU QUINN, GD SALEM, J BARON, I CHO, K FOLEY, M FANG, H AF QUINN, GD SALEM, J BARON, I CHO, K FOLEY, M FANG, H TI FRACTURE-TOUGHNESS OF ADVANCED CERAMICS AT ROOM-TEMPERATURE SO JOURNAL OF RESEARCH OF THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY LA English DT Article DE ADVANCED CERAMIC; ALUMINA; FRACTURE; FRACTURE TOUGHNESS; INDENTATION; ROUND-ROBIN; SILICON NITRIDE; ZIRCONIA ID CRACK-GROWTH; TOUGHENED ALUMINA; SURFACE CRACK; Y-TZP; INDENTATION; STRENGTH; BEHAVIOR; DAMAGE; BEAMS AB This report presents the results obtained by the five U.S. participating laboratories in the Versailles Advanced Materials and Standards (VAMAS) round-robin for fracture toughness of advanced ceramics. Three test methods were used- indentation fracture, indentation strength, and single-edge pre-cracked beam, Two materials were tested: a gas-pressure sintered silicon nitride and a zirconia toughness alumina. Consistent results were obtained with the latter two test methods. Interpretation of fracture toughness in the zirconia alumina composite was complicated by R-curve and environmentally-assisted crack growth phenomena. C1 NASA, LEWIS RES CTR, STRUCT INTEGR BRANCH, CLEVELAND, OH 44135 USA. WORCESTER POLYTECH INST, DEPT MECH ENGN, WORCESTER, MA 01609 USA. NORTON IND CERAM CORP, MECH PROPERTIES TESTING LAB ST GOBAIN, NORTHBOROUGH, MA 01532 USA. ALLIED SIGNAL CO, GARRETT AUXILIARY POWER DIV, PHOENIX, AZ 85010 USA. RP QUINN, GD (reprint author), NATL INST STAND & TECHNOL, DIV CERAM, GAITHERSBURG, MD 20899 USA. NR 47 TC 54 Z9 54 U1 1 U2 6 PU US GOVERNMENT PRINTING OFFICE PI WASHINGTON PA SUPERINTENDENT DOCUMENTS,, WASHINGTON, DC 20402-9325 USA SN 1044-677X J9 J RES NATL INST STAN JI J. Res. Natl. Inst. Stand. Technol. PD SEP-OCT PY 1992 VL 97 IS 5 BP 579 EP 607 DI 10.6028/jres.097.026 PG 29 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA KD645 UT WOS:A1992KD64500004 PM 28053447 ER PT J AU BHANU, B SRIDHAR, B AF BHANU, B SRIDHAR, B TI PASSIVE RANGING FOR ROBOTIC SYSTEMS SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Editorial Material C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BHANU, B (reprint author), UNIV CALIF RIVERSIDE,COLL ENGN,VISUALIZAT & INTELLIGENT SYST LAB,RIVERSIDE,CA 92521, 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 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD SEP PY 1992 VL 9 IS 6 BP 705 EP 708 DI 10.1002/rob.4620090602 PG 4 WC Robotics SC Robotics GA JJ583 UT WOS:A1992JJ58300001 ER PT J AU SRIDHAR, B SUORSA, R SMITH, P HUSSIEN, B AF SRIDHAR, B SUORSA, R SMITH, P HUSSIEN, B TI VISION-BASED OBSTACLE DETECTION FOR ROTORCRAFT FLIGHT SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article AB The ability of rotorcraft to fly at low altitude is hindered by the high pilot workload required to avoid obstacles. The development of automation tools that can detect obstacles in the rotorcraft flight path, warn the crew, and interact with the guidance system to avoid detected obstacles would significantly reduce pilot workload and increase safety. This article describes an obstacle detection approach based on feature tracking and recursive range estimation that takes into account the characteristics of rotorcraft flight. The merits and weaknesses of the approach are discussed using image sequences from the laboratory and from flight. RP SRIDHAR, B (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 23 TC 5 Z9 5 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD SEP PY 1992 VL 9 IS 6 BP 709 EP 727 DI 10.1002/rob.4620090603 PG 19 WC Robotics SC Robotics GA JJ583 UT WOS:A1992JJ58300002 ER PT J AU MATTHIES, L AF MATTHIES, L TI PASSIVE STEREO RANGE IMAGING FOR SEMIAUTONOMOUS LAND NAVIGATION SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article ID COMPUTATIONAL VISION; REGULARIZATION; SCALE AB Many navigation tasks, such as the use of unmanned vehicles for planetary exploration or defense reconnaissance, require onboard range sensors to automatically detect obstacles in the path of a vehicle. Passive ranging via stereo triangulation, or stereo vision, is a very attractive approach to obstacle detection because it is nonemissive, nonmechanical, nonscanning, and compatible with stereographic viewing by human operators. However, several problems have restricted the practicality of stereo ranging in the past, including limitations on the speed, reliability, and generality of existing stereo matching algorithms. This situated has changed, because the Jet Propulsion Laboratory (JPL) recently demonstrated the first semi-autonomous, robotic traverses of natural terrain to use stereo vision for obstacle detection, with all computing onboard the vehicle. This article reviews the main algorithmic paradigms for stereo vision, describes a near real-time stereo vision system developed at JPL, and presents experimental results that demonstrate the emerging practically of stereo vision for obstacle detection in semi-autonomous land navigation. RP JET PROP LAB, PASADENA, CA 91109 USA. NR 55 TC 6 Z9 6 U1 0 U2 0 PU JOHN WILEY & SONS INC PI HOBOKEN PA 111 RIVER ST, HOBOKEN, NJ 07030 USA SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD SEP PY 1992 VL 9 IS 6 BP 787 EP 816 DI 10.1002/rob.4620090607 PG 30 WC Robotics SC Robotics GA JJ583 UT WOS:A1992JJ58300006 ER PT J AU GREENDYKE, RB GNOFFO, PA LAWRENCE, RW AF GREENDYKE, RB GNOFFO, PA LAWRENCE, RW TI CALCULATED ELECTRON NUMBER DENSITY PROFILES FOR THE AEROASSIST FLIGHT EXPERIMENT SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SCHEMES AB Basic features of a Microwave Reflectometer Ionization Sensor (MRIS) as designed for use on the Aeroassist Flight Experiment are described. The MRIS is designed to measure the distances into the shock layer of four critical electron number densities corresponding to four frequencies (20, 44, 95, and 140 GHz). A parametric study of the effects of trajectory and several thermochemical nonequilibrium models for reaction rates, translational and vibrational-electronic energy exchange rates, the average electronic excitation level of atoms, and axisymmetric vs three-dimensional effects is conducted for evaluating MRIS contributions to the code validation process. The parametric study, implemented with the Langley Aerothermodynamic Upwind Relaxation Algorithm program, reveals a particular sensitivity of the onset and severity of an electron avalanche phenomena associated with changes in these physical models that lead to strong electron-impact ionization. Predicted electron number density profiles are sensitive to reasonable variations in certain kinetic models; consequently, MRIS measurements could assist the code validation process. C1 NASA,LANGLEY RES CTR,ANTENNA & MICROWAVE RES BRANCH,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665. RP GREENDYKE, RB (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. NR 16 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1992 VL 29 IS 5 BP 621 EP 626 PG 6 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700001 ER PT J AU GREENE, FA GUPTA, RN AF GREENE, FA GUPTA, RN TI VISCOUS EQUILIBRIUM COMPUTATIONS USING PROGRAM LAURA SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID REAL GASES; ALGORITHMS AB Modifications have been made to the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) that enable it to compute viscous airflows under the assumption of thermal and chemical equilibrium. Equilibrium thermodynamic and transport property information are input to the code via curve fits. The periodic updating of this information enables the equilibrium algorithm to perform at a computational rate that is only a small percentage larger than the rate associated with the perfect-gas algorithm. Presented in this article are the results of the initial validation of the modified code. Solutions for surface pressure and heating are presented for the now over slender and blunt cones at realistic re-entry conditions. LAURA solutions are compared with those produced by a viscous shock-layer method, and, for one case considered, with heat transfer data from a flight experiment. For both pressure and heating, the agreement is good. In general, differences in pressures of a few percent were noted, while differences in heating rates were in the 5-10% range. RP GREENE, FA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1992 VL 29 IS 5 BP 627 EP 632 DI 10.2514/3.11502 PG 6 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700002 ER PT J AU GUPTA, RN LEE, KP MOSS, JN SUTTON, K AF GUPTA, RN LEE, KP MOSS, JN SUTTON, K TI VISCOUS SHOCK LAYER ANALYSIS OF THE MARTIAN AEROTHERMAL ENVIRONMENT SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Detailed surface heating and flowfield results have been obtained for the stagnation region of a planetary exploration vehicle entering the Martian atmosphere. A viscous shock layer analysis (which includes an absorbing boundary layer) is used to obtain solutions with and without coupled ablation injection. Recently developed curve fits for the transport and thermodynamic properties of Martian atmospheric and ablation species as well as for the absorption coefficient for CO(4+) are employed. Extensive results are provided at altitudes of 30, 36, and 50 km for bodies with nose radii of 1, 2.3, and 23 m at freestream velocities of 6, 8, 10, and 12 km/s. Sublimation temperature is employed with coupled ablation injection cases, whereas radiative equilibrium wall temperature is used without injection. Only for bodies with large nose radii (23 m or larger) and for velocities of approximately 6 km/s can a reusable heat shield (with the currently available materials) be used. For higher velocities or vehicles with smaller nose radii, an ablative thermal protection system will be required. A comparison with thermochemical nonequilibrium calculations suggests that much of the flow in the shock layer is in thermochemical equilibrium for the cases analyzed. This is one of the first studies for the Martian entry conditions of large size bodies with coupled radiation and ablation injection. C1 VIGYAN INC,HAMPTON,VA 23666. RP GUPTA, RN (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 27 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1992 VL 29 IS 5 BP 633 EP 640 DI 10.2514/3.11503 PG 8 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700003 ER PT J AU LEWIS, MJ MCRONALD, AD AF LEWIS, MJ MCRONALD, AD TI DESIGN OF HYPERSONIC WAVE-RIDERS FOR AEROASSISTED INTERPLANETARY TRAJECTORIES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The aerodynamic performance of a vehicle designed to execute an aerogravity-assisted maneuver, which combines a gravitational turn with a low-drag atmosphere pass, is examined. The advantage of the aerogravity-assisted maneuver, as opposed to a more traditional gravity-assist trajectory, is that, through the use of a controlled atmospheric flight, nearly any deflection angle around a gravitating body can be realized. This holds the promise of providing extremely large values of DELTAV. The success of such a maneuver depends on being able to design a vehicle which can execute sustained atmospheric lifting night at Mach numbers in the range of 50-100 with minimal drag losses, thereby implying the use of hypersonic waveriders designed for high L/D. Some simple modeling is used to demonstrate design rules for the design of such vehicles and to estimate the deterioration of their performance during the night. Two sample aerogravity-assisted maneuvers are detailed, including a close solar approach requiring modest DELTAV and a sprint mission to Pluto. C1 JET PROP LAB,TECH STAFF,PASADENA,CA 91109. RP LEWIS, MJ (reprint author), UNIV MARYLAND,DEPT AEROSP ENGN,COLL PK,MD 20742, USA. NR 15 TC 21 Z9 22 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1992 VL 29 IS 5 BP 653 EP 660 DI 10.2514/3.11506 PG 8 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700006 ER PT J AU BROWN, KG MELFI, LT UPCHURCH, BT WOOD, GM AF BROWN, KG MELFI, LT UPCHURCH, BT WOOD, GM TI DOWNWARD-DEPLOYED TETHERED SATELLITE SYSTEMS, MEASUREMENT TECHNIQUES, AND INSTRUMENTATION - A REVIEW SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID MASS-SPECTROMETER; LOWER THERMOSPHERE; ION COMPOSITION; IONOSPHERE; PLASMA; DENSITY; FIELD; MESOSPHERE; REGIONS; OXYGEN AB Data describing spacecraft atmospheric interactions in the lower terrestrial thermosphere (altitude range between 90 and 200 km) are extremely limited due to the relative inaccessibility of this region to research vehicles. Atmospheric measurements in the lower thermosphere are sparse when compared with measurements on satellites at higher altitudes. Downward-deployed tethered satellites are being developed to allow access in a global sense to this important region of the atmosphere. This paper reviews a number of tethered satellite systems, emphasizing downward-deployed systems to measure properties in the lower thermosphere; the physics and chemistry of the lower thermosphere; the interactions of the lower thermosphere with high-velocity tethered satellites; and the performance capabilities of existing and new instrumentation to measure atmospheric, aerodynamic, and aerothermodynamic properties that include radiative emission (glow), magnetism, and the distribution of the neutral gas, excited species, ions, and electrons. It is concluded that these tethered satellite systems, when implemented, offer a unique opportunity to investigate regions of the atmosphere previously inaccessible to conventional satellites. C1 NASA,LANGLEY RES CTR,DIV INSTRUMENT RES,HAMPTON,VA 23665. RP BROWN, KG (reprint author), OLD DOMINION UNIV,DEPT CHEM & BIOCHEM,NORFOLK,VA 23529, USA. NR 66 TC 3 Z9 3 U1 1 U2 3 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 671 EP 677 DI 10.2514/3.11509 PG 7 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700009 ER PT J AU KANDULA, M MARTIN, FW AF KANDULA, M MARTIN, FW TI NUMERICAL DISSIPATION IN F3D THIN-LAYER NAVIER-STOKES SOLUTION FOR FLOWS WITH WALL TRANSPIRATION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID EQUATIONS; SCHEMES AB Numerical boundary conditions for mass injection/suction at the wall are incorporated in the thin-layer Navier-Stokes code, F3D. The accuracy of the boundary conditions and the code is assessed by a detailed comparison of the predictions of velocity distributions and skin-friction coefficients with exact similarity solutions for laminar flow over a flat plate with variable blowing/suction, and measurements for turbulent flow past a flat plate with uniform blowing. In laminar flow, F3D predictions for friction coefficient compare well with exact similarity solution with and without suction, but the code produces large errors at moderate-to-large values of blowing. These errors are attributed to the numerical dissipation due to Steger-Warming flux-vector splitting in the upwinding (streamwise) direction. This numerical dissipation is shown to yield a slight Mach number dependence of skin-friction coefficient due to blowing in turbulent flow. Predicted surface pressures for turbulent now past an airfoil with mass injection are in qualitative agreement with measurements for a flat plate. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP KANDULA, M (reprint author), LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058, USA. NR 20 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1992 VL 29 IS 5 BP 678 EP 684 DI 10.2514/3.11510 PG 7 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700010 ER PT J AU KORTE, JJ AF KORTE, JJ TI AERODYNAMIC DESIGN OF AXISYMMETRICAL HYPERSONIC WIND-TUNNEL NOZZLES USING A LEAST-SQUARES PARABOLIZED NAVIER-STOKES PROCEDURE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A new procedure, which unifies the best of current classical design practices, computational fluid dynamics (CFD), and optimization procedures, is demonstrated for designing the aerodynamic lines of hypersonic wind-tunnel nozzles. The new procedure can be used to design wind-tunnel nozzles with thick boundary layers where the classical design procedure has been shown to break down. An efficient CFD code, which solves the parabolized Navier-Stokes (PNS) equations, is coupled to a least-squares (LS) optimization procedure. An LS problem is formulated to minimize the difference between the computed flowfield and the objective function, consisting of the centerline Mach number distribution and the exit Mach number and flow angle profiles. The aerodynamic lines of the nozzle are defined using a cubic spline, the slopes of which are optimized with the design procedure. The advantages of the new procedure are that it allows full use of CFD codes in the design process, it can be used to design new nozzles or improve sections of existing nozzles, and it automatically compensates the nozzle contour for viscous effects. The computed flowfield for a Mach 15 helium LS/PNS designed nozzle is compared with the classically designed nozzle and demonstrates a significant improvement in the flow expansion process and uniform core region. RP KORTE, JJ (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665, USA. NR 22 TC 9 Z9 9 U1 0 U2 3 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 685 EP 691 DI 10.2514/3.11511 PG 7 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700011 ER PT J AU CHIARAMONTE, FP FOERSTER, G GOTTI, DJ NEUMANN, ES JOHNSTON, JC DEWITT, KJ AF CHIARAMONTE, FP FOERSTER, G GOTTI, DJ NEUMANN, ES JOHNSTON, JC DEWITT, KJ TI INITIAL STUDY OF VOID FORMATION DURING ALUMINUM SOLIDIFICATION IN REDUCED GRAVITY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID GROWTH AB Void formation due to volumetric shrinkage during aluminum solidification was observed in real time using a radiographic viewing system in normal and reduced gravity. An end-chill directional solidification furnace with water quench was developed to solidify aluminum samples during the approximately 16 s of reduced gravity (+/-0.02g) achieved by flying an aircraft through a parabolic trajectory. The aluminum was contained in a vacuum sealed, rectangular, pyrolytic boron nitride crucible. An ullage space was present during each test. Void formation was recorded for two cases: 1) a nonwetting system, and 2) a wetting system where wetting occurs between the aluminum and the crucible lid. The void formation in the nonwetting case is similar in normal and reduced gravity, with a single vapor cavity forming at the top of the crucible. In the wetting case in reduced gravity, surface tension causes two voids to form in the top corners of the crucible, but in normal gravity only one large void forms across the top. C1 UNIV TOLEDO,TOLEDO,OH 43606. RP CHIARAMONTE, FP (reprint author), NASA,LEWIS RES CTR,DEPT CHEM ENGN,CLEVELAND,OH 44135, USA. NR 15 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 SEP-OCT PY 1992 VL 29 IS 5 BP 704 EP 708 DI 10.2514/3.11513 PG 5 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700014 ER PT J AU CLAYTON, JP TINKER, ML AF CLAYTON, JP TINKER, ML TI CHARACTERIZATION OF ADVANCED FLEXIBLE THERMAL PROTECTION MATERIAL FOR SPACE APPLICATIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This paper describes experimental and analytical characterization of a new flexible thermal protection material known as Tailorable Advanced Blanket Insulation (TABI). This material utilizes a three-dimensional ceramic fabric core structure and an insulation filler. TABI is the leading candidate for use in deployable aeroassisted vehicle designs. Such designs require extensive structural modeling, and the most significant in-plane material properties necessary for model development are measured and analytically verified in this study. First, nonlinear modulus curves are presented for the directions parallel and normal to the fill direction. Trends observed in the modulus profiles are explained in terms of filament behavior. Next, the dominant damping type and approximate magnitudes are determined using log decrement and hysteresis methods. Because of the clothlike nature of the material, unusual test methods are used for damping measurements. Mathematical models are developed for verification of the experimental modulus and damping data, and finally, transverse properties are described in terms of the in-plane properties through use of a finite difference model of a simple TABI configuration. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SYST RES BRANCH,HUNTSVILLE,AL 35812. RP CLAYTON, JP (reprint author), REMTECH INC,HUNTSVILLE,AL 35805, USA. NR 18 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1992 VL 29 IS 5 BP 718 EP 726 DI 10.2514/3.11516 PG 9 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700017 ER PT J AU STANLEY, DO WILHITE, AW ENGLUND, WC LAUBE, JR AF STANLEY, DO WILHITE, AW ENGLUND, WC LAUBE, JR TI COMPARISON OF SINGLE-STAGE AND 2-STAGE AIR-BREATHING LAUNCH VEHICLES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB In this paper a predominantly airbreathing SSTO vehicle is compared with three different TSTO configurations that stage at Mach numbers of 10, 12, and 14. The first stage of the TSTO vehicle uses the same propulsion system type and airframe shape as the SSTO vehicle except for modifications required to integrate the orbiter on top of the first stage. The TSTO configuration incorporates the same technologies, mission, and design methodology as the SSTO vehicle to allow a consistent comparison. The technologies employed on each of the vehicles are consistent with a successful NASP technology development program in the areas of structures, subsystems, and propulsion systems. In an attempt to examine whether or not a more ideally integrated TSTO configuration could be competitive with an SSTO vehicle, the TSTO configurations were each redesigned with several hypothetical assumptions and compared to the reference SSTO vehicle. To determine the effect of structural and subsystem technologies on the relative weights of the SSTO and TSTO configurations, weight sensitivity trades are also presented. A comparison of the results to SSTO and TSTO rocket-powered configurations using the same technologies, mission, and design methodology is also presented. C1 MCDONNELL DOUGLAS SPACE SYST CO,HUNTINGTON BEACH,CA 92647. RP STANLEY, DO (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE ANAL BRANCH,MAIL STOP 365,HAMPTON,VA 23665, USA. NR 10 TC 4 Z9 4 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1992 VL 29 IS 5 BP 735 EP 740 DI 10.2514/3.11518 PG 6 WC Engineering, Aerospace SC Engineering GA JR777 UT WOS:A1992JR77700019 ER EF