FN Thomson Reuters Web of Science™ VR 1.0 PT J AU JOUZEL, J KOSTER, RD SUOZZO, RJ RUSSELL, GL AF JOUZEL, J KOSTER, RD SUOZZO, RJ RUSSELL, GL TI STABLE WATER ISOTOPE BEHAVIOR DURING THE LAST GLACIAL MAXIMUM - A GENERAL-CIRCULATION MODEL ANALYSIS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ICE-CORE RECORD; CLIMATIC RECORD; ANTARCTIC ICE; DEUTERIUM EXCESS; VEIN CALCITE; O-18; PRECIPITATION; CYCLES; GROUNDWATER; SIMULATIONS AB Global water isotope geochemistry during the last glacial maximum (LGM) is simulated with an 8 degrees x 10 degrees atmospheric general circulation model (GCM). The simulation results suggest that the ''spatial'' delta(18)O/temperature relationships observed for the present-day and LGM climates are very similar. Furthermore, the temporal delta(18)O/temperature relationship is similar to the present-day spatial relationship in regions for which the LGM/present-day temperature change is significant. This helps justify the standard practice of applying the latter to the interpretation of paleodata, despite the possible influence of other factors, such as changes in the evaporative sources of precipitation or in the seasonality of precipitation. The model suggests, for example, that temperature shifts inferred from ice core data may differ from the true shifts by only about 30%. C1 CNRS, LAB GLACIOL & GEOPHYS ENVIRONNEMENT, ST MARTIN DHERES, FRANCE. NASA, GODDARD SPACE FLIGHT CTR, HYDROL SCI BRANCH, GREENBELT, MD 20771 USA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. RP JOUZEL, J (reprint author), CENS, CEA,DSM,MODELISAT CLIMATE ENVIRONM LAB, BATIMENT 709, ORNE MERISIERS, F-91191 GIF SUR YVETTE, FRANCE. RI Koster, Randal/F-5881-2012 OI Koster, Randal/0000-0001-6418-6383 NR 54 TC 82 Z9 83 U1 3 U2 27 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD DEC 20 PY 1994 VL 99 IS D12 BP 25791 EP 25801 DI 10.1029/94JD01819 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PY229 UT WOS:A1994PY22900039 ER PT J AU RINSLAND, CP JONES, NB MATTHEWS, WA AF RINSLAND, CP JONES, NB MATTHEWS, WA TI INFRARED SPECTROSCOPIC MEASUREMENTS OF THE TOTAL COLUMN ABUNDANCE OF ETHANE (C2H6) ABOVE LAUDER, NEW-ZEALAND SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Note ID C2-C5 HYDROCARBONS; LOWER STRATOSPHERE; UPPER TROPOSPHERE; LINE PARAMETERS; BANDS; PROPANE; SPECTRA AB Total vertical column abundances of atmospheric ethane (C2H6) have been retrieved from more than 350 high-resolution infrared solar spectra recorded on 129 days between December 1992 and March 1994 at the Network for the Detection of Stratospheric Change (NDSC) station in Lauder, New Zealand (latitude 45.04 degrees S, 169.68 degrees E, 0.37 km altitude). The results are based on nonlinear least squares fits to narrow spectral intervals containing the unresolved C2H6 nu(7) band (P)Q(3) and (R)Q(0) subbranches at 2976.8 and 2986.7 cm-l, respectively. The measured Lauder column abundances show a pronounced seasonal cycle with a maximum value of (8.6 +/- 1.1) x 10(15) molecules cm(-2) in september and a minimum value of (3.8 +/- 0.5) x 10(15) molecules cm(-2) in February. Assuming a realistic vertical distribution for C2H6, these values correspond to surface level volume-mixing ratios of 0.52 and 0.23 ppbv (parts per billion by volume), respectively. The phase and relative amplitude of the Lauder C2H6 seasonal cycle are similar to corresponding values determined from infrared measurements at the Jungfraujoch (46.55 degrees N, 7.98 degrees E, 3.58 km altitude) and Mauna Loa (latitude 19.5 degrees N, longitude 155.6 degrees W, 3.5 km altitude) NDSC stations, but the inferred absolute magnitudes of the Lauder surface level mixing ratios during the same season are significantly lower. The Lauder C2H6 measurements are also compared with published southern hemisphere surface level sampling measurements and two-dimensional model calculations. C1 NATL INST WATER & ATMOSPHER RES CLIMATE, LAUDER 9182, NEW ZEALAND. RP RINSLAND, CP (reprint author), NASA, LANGLEY RES CTR, MAIL STOP 401A, HAMPTON, VA 23665 USA. RI Jones, Nicholas/G-5575-2011 OI Jones, Nicholas/0000-0002-0111-2368 NR 22 TC 8 Z9 8 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD DEC 20 PY 1994 VL 99 IS D12 BP 25941 EP 25945 DI 10.1029/94JD02386 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PY229 UT WOS:A1994PY22900052 ER PT J AU KNOX, L TURNER, MS AF KNOX, L TURNER, MS TI DETECTABILITY OF TENSOR PERTURBATIONS THROUGH ANISOTROPY OF THE COSMIC BACKGROUND-RADIATION SO PHYSICAL REVIEW LETTERS LA English DT Article ID GRAVITATIONAL-WAVES; INFLATIONARY UNIVERSE; GRAND UNIFICATION; COBE SATELLITE; IRAS GALAXIES; MICROWAVE; FLUCTUATIONS; COSMOLOGY; MODELS; SCENARIO C1 UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP KNOX, L (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 38 TC 53 Z9 53 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 DEC 19 PY 1994 VL 73 IS 25 BP 3347 EP 3350 DI 10.1103/PhysRevLett.73.3347 PG 4 WC Physics, Multidisciplinary SC Physics GA PX387 UT WOS:A1994PX38700005 ER PT J AU GOTSIS, PK GUPTILL, JD AF GOTSIS, PK GUPTILL, JD TI FIBER-COMPOSITE THIN SHELLS SUBJECTED TO THERMAL BUCKLING LOADS SO COMPUTERS & STRUCTURES LA English DT Article AB The results of parametric studies to assess the effects of various parameters on the buckling behavior of angle-ply, laminated thin shells in a hot environment are presented in this paper. These results were obtained by using a three-dimensional finite element analysis. An angle-ply, laminated thin shell with fiber orientation of [theta/-theta]2 was subjected to compressive mechanical loads. The laminated thin shell has a cylindrical geometry. The laminate contained T300 graphite fibers embedded in an intermediate-modulus, high-strength (IMHS) matrix. The fiber volume fraction was 55% and the moisture content was 2%. The residual stresses induced into the laminated structure during the curing were taken into account. Parametric studies were performed to examine the effect on the critical buckling load of the following parameters: cylinder length and thickness, internal hydrostatic pressure, different ply thicknesses, different temperature profiles through the thickness of the structure, and different layup configurations and fiber volume fractions. In conjunction with these parameters the ply orientation varied from 0-degree to 90-degrees. Seven ply angles were examined: 0-degree, 15-degrees, 30-degrees, 45-degrees, 60-degrees, 75-degrees, and 90-degrees. The results show that the ply angle theta and the laminate thickness had significant effects on the critical buckling load. The fiber volume fraction and the internal hydrostatic pressure had important effects on the critical buckling load. The cylinder length had a moderate influence on the buckling load. The thin shell with [theta/-theta]2 or [theta/-theta]s angle-ply laminate had better buckling-load performance than the thin shell with [theta]4 off-axis laminate. The temperature profiles through the laminate thickness and various laminates with the same thickness but with the different ply thickness had insignificant effects on the buckling behavior of the thin shells. RP GOTSIS, PK (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 8 TC 6 Z9 6 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD DEC 17 PY 1994 VL 53 IS 6 BP 1263 EP 1274 DI 10.1016/0045-7949(94)90394-8 PG 12 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA PV576 UT WOS:A1994PV57600002 ER PT J AU REDDY, MV GRANDHI, RV HOPKINS, DA AF REDDY, MV GRANDHI, RV HOPKINS, DA TI RELIABILITY-BASED STRUCTURAL OPTIMIZATION - A SIMPLIFIED SAFETY INDEX APPROACH SO COMPUTERS & STRUCTURES LA English DT Article ID DESIGN; PARAMETERS AB A probabilistic optimal design methodology for complex structures modelled with finite element methods is presented. The main emphasis is on developing probabilistic analysis tools suitable for optimization. An advanced second-moment method is employed to evaluate the failure probability of the performance function. The safety indices are interpolated using the information at the mean and most probable failure point. The minimum weight design with an improved safety index limit is achieved by using the extended interior penalty method of optimization. Numerical examples covering beam and plate structures are presented to illustrate the design approach. The results obtained by using the proposed approach are compared with those obtained by using the existing probabilistic optimization techniques. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP REDDY, MV (reprint author), WRIGHT STATE UNIV,DEPT MECH & MAT ENGN,DAYTON,OH 45435, USA. NR 21 TC 37 Z9 39 U1 0 U2 4 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 DEC 17 PY 1994 VL 53 IS 6 BP 1407 EP 1418 DI 10.1016/0045-7949(94)90406-5 PG 12 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA PV576 UT WOS:A1994PV57600014 ER PT J AU ARNOLD, SM SALEEB, AF TAN, HQ ZHANG, Y AF ARNOLD, SM SALEEB, AF TAN, HQ ZHANG, Y TI EXPLICIT ROBUST SCHEMES FOR IMPLEMENTATION OF GENERAL PRINCIPAL VALUE-BASED CONSTRUCTIVE MODELS SO COMPUTERS & STRUCTURES LA English DT Article AB The issue of developing effective and robust schemes to implement general hyperelastic constitutive models is addressed. To this end, special purpose functions for the symbolic derivation, evaluation and automatic FORTRAN code generation of explicit forms for the corresponding stress function and material tangent stiffness tensors are utilized. These explicit forms are valid for the entire deformation range, i.e., with both distinct as well as repeated principal-stretch values. The analytical form of the explicit expressions are given here for the case in which the strain-energy potential, W, is taken as a nonseparable polynomial function of the principal stretches. C1 UNIV AKRON,DEPT CIVIL ENGN,AKRON,OH 44325. UNIV AKRON,DEPT MATH SCI,AKRON,OH 44325. RP ARNOLD, SM (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD DEC 17 PY 1994 VL 53 IS 6 BP 1437 EP 1451 DI 10.1016/0045-7949(94)90409-X PG 15 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA PV576 UT WOS:A1994PV57600017 ER PT J AU NOZETTE, S RUSTAN, P PLEASANCE, LP HORAN, DM REGEON, P SHOEMAKER, EM SPUDIS, PD ACTON, CH BAKER, DN BLAMONT, JE BURATTI, BJ CORSON, MP DAVIES, ME DUXBURY, TC ELIASON, EM JAKOSKY, BM KORDAS, JF LEWIS, IT LICHTENBERG, CL LUCEY, PG MALARET, E MASSIE, MA RESNICK, JH ROLLINS, CJ PARK, HS MCEWEN, AS PRIEST, RE PIETERS, CM REISSE, RA ROBINSON, MS SIMPSON, RA SMITH, DE SORENSON, TC BREUGGE, RWV ZUBER, MT AF NOZETTE, S RUSTAN, P PLEASANCE, LP HORAN, DM REGEON, P SHOEMAKER, EM SPUDIS, PD ACTON, CH BAKER, DN BLAMONT, JE BURATTI, BJ CORSON, MP DAVIES, ME DUXBURY, TC ELIASON, EM JAKOSKY, BM KORDAS, JF LEWIS, IT LICHTENBERG, CL LUCEY, PG MALARET, E MASSIE, MA RESNICK, JH ROLLINS, CJ PARK, HS MCEWEN, AS PRIEST, RE PIETERS, CM REISSE, RA ROBINSON, MS SIMPSON, RA SMITH, DE SORENSON, TC BREUGGE, RWV ZUBER, MT TI THE CLEMENTINE MISSION TO THE MOON - SCIENTIFIC OVERVIEW SO SCIENCE LA English DT Article ID THERMAL EMISSION; COHERENT BACKSCATTER; SURFACE AB In the course of 71 days in lunar orbit, from 19 February to 3 May 1994, the Clementine spacecraft acquired just under two million digital images of the moon at visible and infrared wavelengths. These data are enabling the global mapping of the rock types of the lunar crust and the first detailed investigation of the geology of the lunar polar regions and the lunar far side. In addition, laser-ranging measurements provided the first view of the global topographic figure of the moon. The topography of many ancient impact basins has been measured, and a global map of the thickness of the lunar crust has been derived from the topography and gravity. C1 LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. USN,RES LAB,WASHINGTON,DC 20375. US GEOL SURVEY,FLAGSTAFF,AZ 86001. LUNAR & PLANETARY INST,HOUSTON,TX 77058. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV COLORADO,LASP,BOULDER,CO 80309. CTR NATL ETUD SPATIALES,PARIS,FRANCE. RES SUPPORT INSTRUMENTS,ALEXANDRIA,VA 22314. RAND CORP,SANTA MONICA,CA 90407. UNIV HAWAII MANOA,HONOLULU,HI 96822. APPL COHERENT TECHNOL,HERNDON,VA 22070. PACIFIC ADV TECHNOL,SOLVANG,CA 94550. BROWN UNIV,PROVIDENCE,RI 02912. SCI INQUIRIES,CATONSVILLE,MD 21228. STANFORD UNIV,STANFORD,CA 94305. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. ALLIED SIGNAL AEROSP CO,ALEXANDRIA,VA 22314. SCI APPLICAT INT CORP,WASHINGTON,DC 20024. JOHNS HOPKINS UNIV,BALTIMORE,MD 21218. RP NOZETTE, S (reprint author), BALLIST MISSILE DEF ORG,WASHINGTON,DC, USA. NR 23 TC 253 Z9 263 U1 4 U2 14 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD DEC 16 PY 1994 VL 266 IS 5192 BP 1835 EP 1839 DI 10.1126/science.266.5192.1835 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PX383 UT WOS:A1994PX38300028 PM 17737076 ER PT J AU ZUBER, MT SMITH, DE LEMOINE, FG NEUMANN, GA AF ZUBER, MT SMITH, DE LEMOINE, FG NEUMANN, GA TI THE SHAPE AND INTERNAL STRUCTURE OF THE MOON FROM THE CLEMENTINE MISSION SO SCIENCE LA English DT Article ID TERRESTRIAL PLANETS; HARMONIC-ANALYSIS; GRAVITY MODEL; TECTONICS; BASINS; TOPOGRAPHY; EVOLUTION; VENUS; MARS AB Global topographic and gravitational field models derived from data collected by the Clementine spacecraft reveal a new picture of the shape and internal structure of the moon. The moon exhibits a 16-kilometer range of elevation, with the greatest topographic excursions occurring on the far side. Lunar highlands are in a state of near-isostatic compensation, whereas impact Basins display a wide range of compensation states that do not correlate simply with basin size or age. A global crustal thickness map reveals crustal thinning under all resolvable lunar basins. The results indicate that the structure and thermal history of the moon are more complex than was previously believed. C1 NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. RP ZUBER, MT (reprint author), JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,BALTIMORE,MD 21218, USA. RI Lemoine, Frank/D-1215-2013; Neumann, Gregory/I-5591-2013 OI Neumann, Gregory/0000-0003-0644-9944 NR 38 TC 245 Z9 271 U1 3 U2 15 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD DEC 16 PY 1994 VL 266 IS 5192 BP 1839 EP 1843 DI 10.1126/science.266.5192.1839 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PX383 UT WOS:A1994PX38300029 PM 17737077 ER PT J AU LUCEY, PG SPUDIS, PD ZUBER, M SMITH, D MALARET, E AF LUCEY, PG SPUDIS, PD ZUBER, M SMITH, D MALARET, E TI TOPOGRAPHIC-COMPOSITIONAL UNITS ON THE MOON AND THE EARLY EVOLUTION OF THE LUNAR CRUST SO SCIENCE LA English DT Article AB The distribution of elevations on the moon determined by Clementine deviates strongly from a normal distribution, suggesting that several geologic processes have influenced the topography. The hypsograms for the near side and far side of the moon are distinctly different, and these differences correlate with differences in composition as determined by Apollo orbital geochemistry, Clementine global multispectral imaging, and groundbased spectroscopy. The hypsograms and compositional data indicate the presence of at least five compositional-altimetric units. The lack of fill of the South Pole-Aitken Basin by mare basalts suggests poor production efficiency of mare basalt in the mantle of this area of the moon. C1 LUNAR & PLANETARY INST,HOUSTON,TX 77058. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. APPL COHERENT TECHNOL,HERNDON,VA 22070. RP LUCEY, PG (reprint author), UNIV HAWAII MANOA,HAWAII INST GEOPHYS & PLANETOL,2525 CORREA RD,HONOLULU,HI 96822, USA. NR 21 TC 39 Z9 41 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 DEC 16 PY 1994 VL 266 IS 5192 BP 1855 EP 1858 DI 10.1126/science.266.5192.1855 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PX383 UT WOS:A1994PX38300033 PM 17737081 ER PT J AU MCEWEN, AS ROBINSON, MS ELIASON, EM LUCEY, PG DUXBURY, TC SPUDIS, PD AF MCEWEN, AS ROBINSON, MS ELIASON, EM LUCEY, PG DUXBURY, TC SPUDIS, PD TI CLEMENTINE OBSERVATIONS OF THE ARISTARCHUS REGION OF THE MOON SO SCIENCE LA English DT Article ID LUNAR; SPECTROSCOPY; REFLECTANCE; DEPOSITS AB Multispectral and topographic data acquired by the Clementine spacecraft provide information on the composition and geologic history of the Aristarchus region of the moon. Altimetry profiles show;the Aristarchus plateau dipping about 1 degrees to the north-northwest and rising about 2 kilometers above the surrounding lavas of Oceanus Procellarum to the south. Dark, reddish pyroclastic glass covers the plateau to average depths of 10 to 30 meters, as determined from the estimated excavation depths of 100- to 1000-meter-diameter craters that have exposed materials below the pyroclastics. These craters and the walls of sinuous rilles also show that mare basalts underlie the pyroclastics across much of the plateau. Near-infrared images of Aristarchus crater reveal olivine-rich materials and two kilometer-sized outcrops of anorthosite in the central peaks. The anorthosite could be either a derivative of local magnesium-suite magmatism or a remnant of the ferroan anorthosite crust that formed over the primordial magma ocean. C1 UNIV HAWAII MANOA,DIV PLANETARY GEOSCI,HONOLULU,HI 96822. CALTECH,JET PROP LAB,PASADENA,CA 91109. LUNAR & PLANETARY INST,HOUSTON,TX 77058. RP MCEWEN, AS (reprint author), US GEOL SURVEY,FLAGSTAFF,AZ 86001, USA. NR 33 TC 63 Z9 69 U1 3 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD DEC 16 PY 1994 VL 266 IS 5192 BP 1858 EP 1862 DI 10.1126/science.266.5192.1858 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PX383 UT WOS:A1994PX38300034 PM 17737082 ER PT J AU CARTER, DC CHANG, B HO, JX KEELING, K KRISHNASAMI, Z AF CARTER, DC CHANG, B HO, JX KEELING, K KRISHNASAMI, Z TI PRELIMINARY CRYSTALLOGRAPHIC STUDIES OF 4 CRYSTAL FORMS OF SERUM-ALBUMIN SO EUROPEAN JOURNAL OF BIOCHEMISTRY LA English DT Article AB Several crystal forms of serum albumin suitable for three-dimensional structure determination have been grown. These forms include crystals of recombinant and wild-type human serum albumin, baboon serum albumin, and canine serum albumin. The intrinsic limits of X-ray diffraction for these crystals are in the range 0.28-0.22 nm. Two of the crystal forms produced from human and canine albumin include incorporated long-chain fatty acids. Molecular replacement experiments have been successfully conducted on each crystal form using the previously determined atomic coordinates of human serum albumin illustrating the conserved tertiary structure. RP CARTER, DC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,STRUCT BIOL LAB,BIOPHYS BRANCH,ES76,HUNTSVILLE,AL 35812, USA. NR 20 TC 176 Z9 183 U1 0 U2 16 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0014-2956 J9 EUR J BIOCHEM JI Eur. J. Biochem. PD DEC 15 PY 1994 VL 226 IS 3 BP 1049 EP 1052 DI 10.1111/j.1432-1033.1994.01049.x PG 4 WC Biochemistry & Molecular Biology SC Biochemistry & Molecular Biology GA QH606 UT WOS:A1994QH60600035 PM 7813459 ER PT J AU JORDANOVA, VK KOZYRA, JU KHAZANOV, GV NAGY, AF RASMUSSEN, CE FOK, MC AF JORDANOVA, VK KOZYRA, JU KHAZANOV, GV NAGY, AF RASMUSSEN, CE FOK, MC TI A BOUNCE-AVERAGED KINETIC-MODEL OF THE RING CURRENT ION POPULATION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOSPHERE AB A bounce-averaged ring current kinetic model for arbitrary pitch angle, including losses due to charge exchange and Coulomb collisions along ion drift paths, is developed and solved numerically. Results from simplified model runs, intended to illustrate the effects of adiabatic drifts and collisional losses on the proton population, are presented. The processes of i) particle acceleration under the conditions of time-independent magnetospheric electric fields; ii) a predominant loss of particles with small pitch angles due to charge exchange; and iii) a buildup of a low-energy population caused by the Coulomb drag energy degradation, are discussed. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP JORDANOVA, VK (reprint author), UNIV MICHIGAN,DEPT ATMOSPHER & SPACE SCI,SPACE PHYS RES LAB,2455 HAYWARD ST,ANN ARBOR,MI 48109, USA. RI Fok, Mei-Ching/D-1626-2012; OI Jordanova, Vania/0000-0003-0475-8743 NR 21 TC 56 Z9 57 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 DEC 15 PY 1994 VL 21 IS 25 BP 2785 EP 2788 DI 10.1029/94GL02695 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QA222 UT WOS:A1994QA22200003 ER PT J AU MCGEE, TJ NEWMAN, P GROSS, M SINGH, U GODIN, S LACOSTE, AM MEGIE, G AF MCGEE, TJ NEWMAN, P GROSS, M SINGH, U GODIN, S LACOSTE, AM MEGIE, G TI CORRELATION OF OZONE LOSS WITH THE PRESENCE OF VOLCANIC AEROSOLS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC OZONE; MT PINATUBO; LIDAR AB Statistically significant reductions of ozone compared to a climatological profile have been measured above the Observatoire de Haute Provence (OHP) in Southern France (43.9 degrees N, 5.7 degrees E) during the months of July and August, 1992. Lidar profiles of ozone, temperature and aerosols were recorded on 25 separate nights during that time. The change in the ozone profile is correlated with the presence of volcanic aerosols from the eruption of Mt. Pinatubo. The total ozone loss amounts to approximately a 10% reduction in the total ozone column over OHP. C1 HUGHES STX CORP,LANHAM,MD. CNRS,SERV AERON,PARIS,FRANCE. RP MCGEE, TJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Newman, Paul/D-6208-2012; McGee, Thomas/G-4951-2013 OI Newman, Paul/0000-0003-1139-2508; NR 10 TC 17 Z9 17 U1 1 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 DEC 15 PY 1994 VL 21 IS 25 BP 2801 EP 2804 DI 10.1029/94GL02350 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QA222 UT WOS:A1994QA22200007 ER PT J AU FRANK, LA PATERSON, WR ACKERSON, KL KOKUBUN, S YAMAMOTO, T FAIRFIELD, DH LEPPING, RP AF FRANK, LA PATERSON, WR ACKERSON, KL KOKUBUN, S YAMAMOTO, T FAIRFIELD, DH LEPPING, RP TI OBSERVATIONS OF PLASMAS ASSOCIATED WITH THE MAGNETIC SIGNATURE OF A PLASMOID IN THE DISTANT MAGNETOTAIL SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NEAR-EARTH; FLUX ROPES AB The three-dimensional electron and positive ion velocity distributions were examined for four events for which the magnetic signature of plasmoids occurred at the Geotail spacecraft position in Earth's distant magnetotail. The proton bulk parameters and the electron velocity distributions for one of the events are presented in order to characterize the qualitative character of the set of events. The north-to-south turnings of the magnetic field that were taken for evidence of the passage of a plasmoid were often accompanied by a significant strong core of B-y that was centered on the transition of B-z from north to south. The magnetic signatures thus appeared to be more indicative of flux ropes than of classical plasmoids with weak core fields. The proton and electron bulk velocities in these magnetic structures are not equal, a situation that provides an earthward current. The plasma beta was typically one or greater. Counterstreaming of low-energy electrons was often found on the magnetic field lines around the central magnetic core and suggested the existence of a closed field line topology in these regions. These events appeared to be the tailward flowing debris from acceleration processes occurring in the vicinity of a separator positioned nearer to Earth. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,TOYOKAWA,AICHI 442,JAPAN. INST SPACE & ASTRONAUT SCI,KANAGAWA 229,JAPAN. RP FRANK, LA (reprint author), UNIV IOWA,DEPT PHYS & ASTRON,VAN ALLEN HALL,IOWA CITY,IA 52242, USA. RI Paterson, William/F-5684-2012 NR 13 TC 26 Z9 26 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 DEC 15 PY 1994 VL 21 IS 25 BP 2967 EP 2970 DI 10.1029/94GL01604 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QA222 UT WOS:A1994QA22200051 ER PT J AU WILLIAMS, DJ LUI, ATY MCENTIRE, RW ANGELOPOULOS, V JACQUEY, C CHRISTON, SP FRANK, LA ACKERSON, KL PATERSON, WR KOKUBUN, S YAMAMOTO, T FAIRFIELD, DH AF WILLIAMS, DJ LUI, ATY MCENTIRE, RW ANGELOPOULOS, V JACQUEY, C CHRISTON, SP FRANK, LA ACKERSON, KL PATERSON, WR KOKUBUN, S YAMAMOTO, T FAIRFIELD, DH TI MAGNETOPAUSE ENCOUNTERS IN THE MAGNETOTAIL AT DISTANCES OF SIMILAR-TO-80 R(E) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LATITUDE BOUNDARY-LAYER AB The GEOTAIL satellite experienced several encounters with the magnetopause during the interval 0300 to 0600 hours on 27 October 1992 at a gsm location of (X,Y,Z) similar to(-81,-8,7.5) R(e). Energetic ions of both solar wind and ionospheric origin (H+, He++, and O+) were observed streaming in the anti-solar direction on both the lobe and magnetosheath side of the plasma mantle-magnetosheath boundary, with maximum fluxes occurring at the boundary. Even though the mantle plasma had penetrated well into the lobe through convective drift, the energetic ions were observed only at the magnetopause and provided a clear signature of the boundary region. Using a measured convective drift velocity and observed energetic particle anisotropies, we estimated that the maximum distance from GEOTAIL that the energetic ions could have been accelerated or made contact with the boundary field lines was < 8-39 R(e), implying that both solar wind and ionospheric ions are accelerated and contact the magnetopause many tens of earth radii behind the earth. We further found that the unusual magnetopause positions encountered at this time could be explained in part by solar wind aberration effects. However additional processes (e. g., magnetospheric breathing modes, convoluted tail topologies) are required to fully explain these observations. C1 UNIV MARYLAND,COLLEGE PK,MD 20742. UNIV IOWA,IOWA CITY,IA 52242. NAGAOKA UNIV TECHNOL,STEL,TOYOKAWA 442,JAPAN. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WILLIAMS, DJ (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,JOHNS HOPKINS RD,LAUREL,MD 20723, USA. RI Paterson, William/F-5684-2012 NR 8 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 DEC 15 PY 1994 VL 21 IS 25 BP 3007 EP 3010 DI 10.1029/94GL01298 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QA222 UT WOS:A1994QA22200061 ER PT J AU CHRISTON, SP GLOECKLER, G WILLIAMS, DJ MUKAI, T MCENTIRE, RW JACQUEY, C ANGELOPOULOS, V LUI, ATY KOKUBUN, S FAIRFIELD, DH HIRAHARA, M YAMAMOTO, T AF CHRISTON, SP GLOECKLER, G WILLIAMS, DJ MUKAI, T MCENTIRE, RW JACQUEY, C ANGELOPOULOS, V LUI, ATY KOKUBUN, S FAIRFIELD, DH HIRAHARA, M YAMAMOTO, T TI ENERGETIC ATOMIC AND MOLECULAR-IONS OF IONOSPHERIC ORIGIN OBSERVED IN DISTANT MAGNETOTAIL FLOW-REVERSAL EVENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GEOTAIL; EVOLUTION AB Energetic atomic (O+1 and N+1) and molecular (O-2(+1), NO+1, and N-2(+1)) ions of ionospheric origin were observed in Earth's magnetotail at X similar to -146 R(E) during two plasma sheet sunward/tailward now-reversal events measured by instruments on the GEOTAIL spacecraft. These events were associated with concurrent ground-measured geomagnetic disturbance intensification at auroral- and mid-latitudes (Kp = 7(-)). Energetic ions in the sunward-component and tailward flows were from both the solar wind and ionosphere. Plasma and energetic ions participated in the flows. During tailward flow, ionospheric origin ion abundance ratios at similar to 200-900 km/s in the rest frame were N+1/O+1 = similar to 25-30% and (O-2(+1), NO+1, and N-2(+1))/O+1 = similar to 1-2%. We argue that tailward flow most likely initiated similar to 80-100 R(E) tailward of Earth and molecular ions were in the plasma sheet prior to geomagnetic intensification onset. C1 JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 21042. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,TOKYOKAWA 442,JAPAN. UNIV TOKYO,DEPT EARTH & PLANETARY PHYS,TOKYO 113,JAPAN. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP CHRISTON, SP (reprint author), UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742, USA. NR 13 TC 21 Z9 21 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 DEC 15 PY 1994 VL 21 IS 25 BP 3023 EP 3026 DI 10.1029/94GL02095 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QA222 UT WOS:A1994QA22200065 ER PT J AU HO, CM TSURUTANI, BT SMITH, EJ FELDMAN, WC AF HO, CM TSURUTANI, BT SMITH, EJ FELDMAN, WC TI A DETAILED EXAMINATION OF A X-LINE REGION IN THE DISTANT TAIL - ISEE-3 OBSERVATIONS OF JET FLOW AND B-Z REVERSALS AND A PAIR OF SLOW SHOCKS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GEOMAGNETIC TAIL; MODE SHOCKS; PLASMA; MAGNETOTAIL AB We report an observation of Petschek-type magnetic reconnection at a distant neutral line (X = -230 R(e), July 8, 1983) with a full set of signatures of the magnetic merging process. These features include a reversal of plasma flows from earthward to tailward, a pair of slow shocks and the magnetic field X-type line. These two slow shocks are shown to satisfy the shock criteria used by Feldman et al. [1987]. The spacecraft first crosses a slow shock to enter the earthward flowing plasmasheet with velocity of about 440 km/s. The embedded magnetic field has a positive B-z component. The spacecraft next enters a region of tailward plasma flow with speed similar to 670 km/s and an embedded negative B-z, indicating entry into the plasmasheet tailward of the X-line. These observed velocities are comparable to calculated velocities based on Rankine-Hugoniot conservation relationships. The spacecraft subsequently returns into the south tail lobe by crossing another slow shock. Coplanarity analyses show that the two slow shocks have orientations consistent with that predicted by the Petschek reconnection model. We note that this event occurs during northward interplanetary magnetic fields. Thus, a magnetic stress built-up in the distant tail may be responsible for this reconnection process. C1 LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP HO, CM (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 13 TC 18 Z9 18 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 15 PY 1994 VL 21 IS 25 BP 3031 EP 3034 DI 10.1029/94GL02096 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QA222 UT WOS:A1994QA22200067 ER PT J AU SALAMA, F JOBLIN, C ALLAMANDOLA, LJ AF SALAMA, F JOBLIN, C ALLAMANDOLA, LJ TI ELECTRONIC ABSORPTION-SPECTROSCOPY OF MATRIX-ISOLATED POLYCYCLIC AROMATIC HYDROCARBON CATIONS .2. THE PHENANTHRENE CATION (C14H10+) AND ITS 1-METHYL DERIVATIVE SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID DIFFUSE INTERSTELLAR BANDS; PHOTOELECTRON-SPECTRA; POLYNUCLEAR AROMATICS; CONDENSED AROMATICS; NAPHTHALENE; ULTRAVIOLET; IONIZATION; EXTINCTION; C10H8+; ION RP SALAMA, F (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 44 TC 73 Z9 73 U1 1 U2 7 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 DEC 15 PY 1994 VL 101 IS 12 BP 10252 EP 10262 DI 10.1063/1.467905 PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QJ592 UT WOS:A1994QJ59200006 PM 11539562 ER PT J AU FU, LL CHRISTENSEN, EJ YAMARONE, CA LEFEBVRE, M MENARD, Y DORRER, M ESCUDIER, P AF FU, LL CHRISTENSEN, EJ YAMARONE, CA LEFEBVRE, M MENARD, Y DORRER, M ESCUDIER, P TI TOPEX/POSEIDON MISSION OVERVIEW SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ELECTROMAGNETIC BIAS; GRAVITATIONAL MODEL; RADAR ALTIMETRY; OCEAN TIDES; SATELLITE; CIRCULATION; GEOSAT AB TOPEX/POSEIDON is the first space mission specifically designed and conducted for studying the circulation of the world's oceans. The mission is jointly conducted by the United States and France. A state-of-the-art radar altimetry system is used to measure the precise height of sea level, from which information on the ocean circulation is obtained. The satellite, launched on August 10, 1992, has been making observations of the global oceans with unprecedented accuracy since late September 1999. To meet the stringent measurement accuracy required for ocean circulation studies, a number of innovative improvements have been made to the mission design, including the first dual-frequency space-borne radar altimeter capable of retrieving the ionospheric delay of the radar signal, a three-frequency microwave radiometer for retrieving the signal delay caused by the water vapor in the troposphere, an optimal model of the Earth's gravity field and multiple satellite tracking systems for precision orbit determination. Additionally, the satellite also carries two experimental instruments to demonstrate new technologies: a single-frequency solid-state altimeter for the technology of low-power, low-weight altimeter and a Global Positioning System receiver for continuous, precise satellite tracking. The performance of the mission's measurement system has been tested by numerous verification studies. The results indicate that the root-sum-square accuracy of a single-pass sea level measurement is 4.7 cm for the TOPEX system and 5.1 cm for the POSEIDON system; both are more than a factor of 2 better than the requirement of 13.7 cm. This global data set is being analyzed by an international team of 200 scientists for improved understanding of the global ocean circulation as well as the ocean tides, geodesy, and geodynamics, and ocean wind and waves. The mission is designed to last for at least 3 years with a possible extension to 6 years. The multiyear global data set will go a long way toward understanding the ocean circulation and its variability in relation to climate change. A summary of the mission's systems and their performance as well as the mission's science team is presented in the paper. C1 CTR NATL ETUD SPATIALES,F-31055 TOULOUSE,FRANCE. RP FU, LL (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS-300-323,PASADENA,CA 91109, USA. NR 54 TC 467 Z9 492 U1 4 U2 20 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 DEC 15 PY 1994 VL 99 IS C12 BP 24369 EP 24381 DI 10.1029/94JC01761 PG 13 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300001 ER PT J AU TAPLEY, BD RIES, JC DAVIS, GW EANES, RJ SCHUTZ, BE SHUM, CK WATKINS, MM MARSHALL, JA NEREM, RS PUTNEY, BH KLOSKO, SM LUTHCKE, SB PAVLIS, D WILLIAMSON, RG ZELENSKY, NP AF TAPLEY, BD RIES, JC DAVIS, GW EANES, RJ SCHUTZ, BE SHUM, CK WATKINS, MM MARSHALL, JA NEREM, RS PUTNEY, BH KLOSKO, SM LUTHCKE, SB PAVLIS, D WILLIAMSON, RG ZELENSKY, NP TI PRECISION ORBIT DETERMINATION FOR TOPEX/POSEIDON SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GLOBAL POSITIONING SYSTEM; GRAVITATIONAL MODEL; REFERENCE FRAME; SATELLITE; EARTH; TRACKING; LAGEOS; CIRCULATION; SPOT-2; GEM-T1 AB The TOPEX/POSEIDON mission objective requires that the radial position of the spacecraft be determined with an accuracy better than 13 cm RMS (root mean square). This stringent requirement is an order of magnitude below the accuracy achieved for any altimeter mission prior to the definition of the TOPEX/POSEIDON mission. To satisfy this objective, the TOPEX Precision Orbit Determination (POD) Team was established as a joint effort between the NASA Goddard Space Plight Center and the University of Texas at Austin, with collaboration from the University of Colorado and the Jet Propulsion Laboratory. During the prelaunch development and the postlaunch verification phases, the POD team improved, calibrated, and validated the precision orbit determination computer software systems. The accomplishments include (I) increased accuracy of the gravity and surface force models and (2) improved performance of both the laser ranging and Doppler tracking systems. The result of these efforts led to orbit accuracies for TOPEX/POSEIDON which are significantly better than the original mission requirement. Tests based on data fits, covariance analysis, and orbit comparisons indicate that the radial component of the TOPEX/POSEIDON spacecraft is determined, relative to the Earth's mass center, with an RMS error in the range of 3 to 4 cm RMS. This orbit accuracy, together with the near continuous dual-frequency altimetry from this mission, provides the means to determine the ocean's dynamic topography with an unprecedented accuracy. C1 NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,GREENBELT,MD 20771. HUGHES STX CORP,GREENBELT,MD. RP TAPLEY, BD (reprint author), UNIV TEXAS,CTR SPACE RES C0605,AUSTIN,TX 78712, USA. RI Luthcke, Scott/D-6283-2012 NR 82 TC 168 Z9 177 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24383 EP 24404 DI 10.1029/94JC01645 PG 22 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300002 ER PT J AU NEREM, RS LERCH, FJ MARSHALL, JA PAVLIS, EC PUTNEY, BH TAPLEY, BD EANES, RJ RIES, JC SCHUTZ, BE SHUM, CK WATKINS, MM KLOSKO, SM CHAN, JC LUTHCKE, SB PATEL, GB PAVLIS, NK WALLIAMSON, RG RAPP, RH BIANCALE, R NOUEL, F AF NEREM, RS LERCH, FJ MARSHALL, JA PAVLIS, EC PUTNEY, BH TAPLEY, BD EANES, RJ RIES, JC SCHUTZ, BE SHUM, CK WATKINS, MM KLOSKO, SM CHAN, JC LUTHCKE, SB PATEL, GB PAVLIS, NK WALLIAMSON, RG RAPP, RH BIANCALE, R NOUEL, F TI GRAVITY MODEL DEVELOPMENT FOR TOPEX/POSEIDON - JOINT GRAVITY MODEL-1 AND MODEL-2 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GRAVITATIONAL MODEL; TEMPORAL VARIATIONS; ORBIT DETERMINATION; OCEANLESS EARTH; SATELLITE; LAGEOS; FIELD; CIRCULATION; COEFFICIENT; IMPROVEMENT AB The TOPEX/POSEIDON (TIP) prelaunch Joint Gravity Model-1 (JGM-1) and the postlaunch JGM-2 Earth gravitational models have been developed to support precision orbit determination for T/P. Each of these models is complete to degree 70 in spherical harmonics and was computed from a combination of satellite tracking data, satellite altimetry, and surface gravimetry. While improved orbit determination accuracies for T/P have driven the improvements in the models, the models are general in application and also provide an improved geoid for oceanographic computations. The postlaunch model, JGM-2, which includes T/P satellite laser ranging (SLR) and Doppler orbitography and radiopositioning integrated by satellite (DORIS) tracking data, introduces radial orbit errors for TIP that are only 2 cm RMS with the commission errors of the marine geoid for terms to degree 70 being +/- 25 cm. Errors in modeling the nonconservative forces acting on T/P increase the total radial errors to only 3-4 cm RMS, a result much better than premission goals. While the orbit accuracy goal for T/P has been far surpassed, geoid errors still prevent the absolute determination of the ocean dynamic topography for wavelengths shorter than about 2500 km., Only a dedicated gravitational field satellite mission will likely provide the necessary improvement in the geoid. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. UNIV TEXAS,CTR SPACE RES,AUSTIN,TX 78712. HUGHES STX CORP,LANHAM,MD. OHIO STATE UNIV,DEPT GEODET SCI & SURVEYING,COLUMBUS,OH 43210. CTR NATL ETUD SPATIALES,F-31055 TOULOUSE,FRANCE. RP NEREM, RS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODESY BRANCH,CODE 926,GREENBELT,MD 20771, USA. RI Luthcke, Scott/D-6283-2012 NR 90 TC 114 Z9 114 U1 2 U2 7 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 DEC 15 PY 1994 VL 99 IS C12 BP 24421 EP 24447 DI 10.1029/94JC01376 PG 27 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300004 ER PT J AU BERTIGER, WI BARSEVER, YE CHRISTENSEN, EJ DAVIS, ES GUINN, JR HAINES, BJ IBANEZMEIER, RW JEE, JR LICHTEN, SM MELBOURNE, WG MUELLERSCHOEN, RJ MUNSON, TN VIGUE, Y WU, SC YUNCK, TP SCHUTZ, BE ABUSALI, PAM RIM, HJ WATKINS, MM WILLIS, P AF BERTIGER, WI BARSEVER, YE CHRISTENSEN, EJ DAVIS, ES GUINN, JR HAINES, BJ IBANEZMEIER, RW JEE, JR LICHTEN, SM MELBOURNE, WG MUELLERSCHOEN, RJ MUNSON, TN VIGUE, Y WU, SC YUNCK, TP SCHUTZ, BE ABUSALI, PAM RIM, HJ WATKINS, MM WILLIS, P TI GPS PRECISE TRACKING OF TOPEX/POSEIDON - RESULTS AND IMPLICATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SATELLITE; TIDES AB A reduced dynamic filtering strategy that exploits the unique geometric strength of the Global Positioning System(GPS) to minimize the effects of force model errors has yielded orbit solutions for TOPEX/POSEIDON which appear accurate to better than 3 cm (1 sigma) in the radial component. Reduction of force model error also reduces the geographic correlation of the orbit error. With a traditional dynamic approach, GPS yields radial orbit accuracies of 4-5 cm, comparable to the accuracy delivered by satellite laser ranging and the Doppler orbitography and radio positioning integrated by satellite (DORIS) tracking system. A portion of the dynamic orbit error is in the Joint Gravity Model-2 (JGM-2); GPS data from TOPEX/POSEIDON can readily reveal that error and have been used to improve the gravity model. C1 UNIV TEXAS,CTR SPACE RES,AUSTIN,TX 78712. INST GEOG NATL,F-94160 ST MANDE,FRANCE. RP BERTIGER, WI (reprint author), CALTECH,JET PROP LAB,48000 OAK GROVE DR,PASADENA,CA 91109, USA. RI Willis, Pascal/A-8046-2008 OI Willis, Pascal/0000-0002-3257-0679 NR 44 TC 97 Z9 110 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24449 EP 24464 DI 10.1029/94JC01171 PG 16 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300005 ER PT J AU CHRISTENSEN, EJ HAINES, BJ KEIHM, SJ MORRIS, CS NORMAN, RA PURCELL, GH WILLIAMS, BG WILSON, BD BORN, GH PARKE, ME GILL, SK SHUM, CK TAPLEY, BD KOLENKIEWICZ, R NEREM, RS AF CHRISTENSEN, EJ HAINES, BJ KEIHM, SJ MORRIS, CS NORMAN, RA PURCELL, GH WILLIAMS, BG WILSON, BD BORN, GH PARKE, ME GILL, SK SHUM, CK TAPLEY, BD KOLENKIEWICZ, R NEREM, RS TI CALIBRATION OF TOPEX/POSEIDON AT PLATFORM HARVEST SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID BIAS AB We present estimates for the mean bias of the TOPEX/POSEIDON NASA altimeter (ALT) and the Centre National d'Etudes Spatiales altimeter (SSALT) using in situ data gathered at Platform Harvest during the first 36 cycles of the mission. Data for 21 overflights of the ALT and six overflights of the SSALT have been analyzed. The analysis includes an independent assessment of in situ measurements of sea level, the radial component of the orbit, wet tropospheric path delay, and ionospheric path delay. (The sign convention used in this paper is such that, to correct the geophysical data record values for sea level, add the bias algebraically. Unless otherwise stated, the uncertainty in a given parameter is depicted by +/-sigma(x), where sigma(x) is the sample standard deviation of x about the mean.) Tide gauges at Harvest provide estimates of sea level with an uncertainty of +/-1.5 cm. The uncertainty in the radial component of the orbit is estimated to be +/-1.3 cm. In situ measurements of tropospheric path delay at Harvest compare to within +/-1.3 cm of the TOPEX/POSEIDON microwave radiometer, and in situ measurements of the ionospheric path delay compare to within -0.4 +/- 0.7 cm of the dual-frequency ALT and 1.1 +/- 0.6 cm of Doppler orbitography and radiopositioning integrated by satellite. We obtain mean bias estimates of -14.5 +/- 2.9 cm for the ALT and +0.9 +/- 3.1 cm for the SSALT (where the uncertainties are based on the standard deviation of the estimated mean (sigma(($) over bar x/y)), which is derived from sample statistics and estimates for errors that cannot be observed). These results are consistent with independent estimates for the relative bias between the two altimeters. A linear regression applied to the complete set of data shows that there is a discernable secular trend in the time series for the ALT bias estimates. A preliminary analysis of data obtained through cycle 48 suggests that the apparent secular drift may be the result of a poorly sampled annual, signal. C1 UNIV COLORADO,COLORADO CTR ASTRODYNAM RES,BOULDER,CO 80309. NOAA,NATL OCEAN SERV,ROCKVILLE,MD 20852. NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,GREENBELT,MD 20771. RP CHRISTENSEN, EJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 48 TC 68 Z9 69 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24465 EP 24485 DI 10.1029/94JC01641 PG 21 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300006 ER PT J AU BORN, GH PARKE, ME AXELRAD, P GOLD, KL JOHNSON, J KEY, KW KUBITSCHEK, DG CHRISTENSEN, EJ AF BORN, GH PARKE, ME AXELRAD, P GOLD, KL JOHNSON, J KEY, KW KUBITSCHEK, DG CHRISTENSEN, EJ TI CALIBRATION OF THE TOPEX ALTIMETER USING A GPS BUOY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GLOBAL POSITIONING SYSTEM AB The use of a spar buoy equipped with a Global Positioning System (GPS) antenna to calibrate the height measurement of the TOPEX radar altimeter is described. In order to determine the height of the GPS antenna phase center above the ocean surface, the buoy was also equipped with instrumentation to measure the instantaneous location of the waterline, and tilt of the buoy from vertical. The experiment was conducted off the California coast near the Texaco offshore oil platform, Harvest, during cycle 34 of the TOPEX/POSEIDON observational period. GPS solutions were computed for the buoy position using two different software packages, K&RS and GIPSY-OASIS II. These solutions were combined with estimates of the waterline location on the buoy to yield the height of the ocean surface. The ocean surface height in an absolute coordinate system combined with knowledge of the spacecraft height from tracking data provides a computed altimeter range measurement. By comparing this computed value to the actual altimeter measurement, the altimeter bias can be calibrated. The altimeter height bias obtained with the buoy using K&RS was -14.6+/-4 cm, while with GIPSY-OASIS II it was -13.1+/-4 cm. These are 0.1 cm and 1.6 cm different from the -14.7+/-4 cm result obtained for this overflight with the tide gauge instruments located on Platform Harvest. C1 CALTECH, JET PROP LAB, PASADENA, CA USA. RP UNIV COLORADO, COLORADO CTR ASTRODYNAM RES, CAMPUS BOX 431, BOULDER, CO 80309 USA. NR 15 TC 34 Z9 35 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9275 EI 2169-9291 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24517 EP 24526 DI 10.1029/94JC00920 PG 10 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300009 ER PT J AU MORRIS, CS GILL, SK AF MORRIS, CS GILL, SK TI EVALUATION OF THE TOPEX/POSEIDON ALTIMETER SYSTEM OVER THE GREAT-LAKES SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID TIDES AB The TOPEX/POSEIDON altimeter measurement system is evaluated for the first 46 repeat cycles (September 23, 1992-December 23, 1993) using tracks over the Great Lakes. The temporal variations in lake level are removed from the altimeter measurements using in situ lake level measurements, thus permitting the performance of the altimeter system to be assessed. For the NASA altimeter, the root-mean-square (RMS) scatter of the residuals is 3.95 cm using all the tracks over the lakes. However, some of the scatter in this result is probably due to lake tides or seiche, which can amount to a few centimeters amplitude near the ends of the lakes. When the seven best tracks are used, which cross the center of the lakes where tides/seiche effects are minimal, the RMS error is reduced to either 2.9 or 3.0 cm, depending on whether the Centre National d'Etudes Spatiales (CNES) or NASA orbit is used. This places an upper limit on the error budget of the altimeter system, excluding ocean tides and inverse barometer effect. There are several short-period variations in the residuals. The most pronounced is a 55-day period, with a 1-cm amplitude, which we believe is (at least in part) due to orbit error. When the model-derived wet tropospheric correction is substituted for the TOPEX microwave radiometer correction, the RMS error increases significantly, possibly resulting in an annual cycle of a few centimeters. Evaluation of the ionospheric correction indicates that the dual-frequency correction provides an average improvement of 0.85 cm over the Doppler orbitography and radiopositioning integrated by satellite (DORIS) correction. Although there are insufficient data to directly assess the CNES altimeter, the relative bias between the altimeters is estimated to be either -14.3 or -15.6 cm (NASA altimeter measuring short), depending on whether the DORIS or dual-frequency ionospheric correction is applied to the NASA altimeter. C1 NOAA,NATL OCEAN SERV,SILVER SPRING,MD. RP MORRIS, CS (reprint author), CALTECH,JET PROP LAB,MS 300-319,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 59 Z9 65 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24527 EP 24539 DI 10.1029/94JC01642 PG 13 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300010 ER PT J AU NEREM, RS SCHRAMA, EJ KOBLINSKY, CJ BECKLEY, BD AF NEREM, RS SCHRAMA, EJ KOBLINSKY, CJ BECKLEY, BD TI A PRELIMINARY EVALUATION OF OCEAN TOPOGRAPHY FROM THE TOPEX/POSEIDON MISSION SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEASAT ALTIMETER DATA; SATELLITE ALTIMETRY; GEOSAT ALTIMETRY; PACIFIC-OCEAN; SEASONAL VARIABILITY; GENERAL-CIRCULATION; DYNAMIC TOPOGRAPHY; GRAVITY-FIELD; LEVEL; MODEL AB We have analyzed 50 ten-day cycles of TOPEX/POSEIDON (T/P) altimeter data to evaluate the ocean dynamic topography and its temporal variations. We have employed data from both the U.S. and French altimeters along with the NASA precision orbits in this analysis. Errors in the diurnal and semidiurnal components of the Cartwright-Ray tide model have been sinificantly reduced using a correction developed from T/P altimeter data by Schrama and Ray (this issue). A hybrid geoid model formed from a combination of JGM-2 and OSU91A was employed, as well as a geoid model based solely on OSU91A. The long wavelengths of the mean dynamic topography show considerable improvement over previous missions based on comparisons to historical hydrographic data, although geoid error still corrupts the dynamic topography for wavelengths shorter than 2500 km. The RMS variability is similar to previous results from Geosat, with background ''noise'' approaching 3 cm RMS. The computed annual and semiannual variations are also similar to previous Geosat results, although the hemispheric distribution of the annual heating cycle is much better represented in the T/P results. They also compare reasonably well with the Levitus hydrographic compilation in the northern hemisphere, although the T/P variations generally have larger amplitudes. Ten-day average maps of variations in sea level compare well with simultaneous measurements at ocean tide gauges, with RMS differences of less than 4 cm and correlations greater than 0.6 for most of the island gauges. Time-longitude plots of these sea level variations at different latitudes in the Pacific clearly show the presence of equatorial Kelvin waves and Rossby waves, with the wave speeds agreeing well with theoretical and observed values. Measurement of variations in global sea level over cycles 2-51 have an RMS variability of 6.3 mm and a rate of change of -3.5 +/- 8 mm/yr, the uncertainty primarily due to insufficient averaging of the interannual and periodic sea level variations. With several more years of data and accurate monitoring of the altimeter drift at the calibration sites, TIP has the potential for providing a precise (+/- 1 mm/yr) estimate of the rate of global sea level rise. These results show that the accuracy of the T/P measurements of sea level has dramatically improved over previous missions, with estimated time variable errors of 4 cm or less (1 sigma). Although geographically correlated orbit errors have also been reduced to the few centimeter level, further improvement in determinations of the mean dynamic topography will be difficult to obtain until a more accurate model of the marine geoid is available. C1 NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771. HUGHES STX CORP,GREENBELT,MD. RP NEREM, RS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,CODE 926,GREENBELT,MD 20771, USA. NR 68 TC 69 Z9 70 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24565 EP 24583 DI 10.1029/94JC01431 PG 19 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300013 ER PT J AU FU, LL PIHOS, G AF FU, LL PIHOS, G TI DETERMINING THE RESPONSE OF SEA-LEVEL TO ATMOSPHERIC-PRESSURE FORCING USING TOPEX/POSEIDON DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID BAROMETRIC-PRESSURE; PACIFIC-OCEAN; VARIABILITY; TIDES; MODEL AB The static response of sea level to the forcing of atmospheric pressure, the so-called inverted barometer (IB) effect, is investigated using TOPEX/POSEIDON data. This response, characterized by the rise and fall of sea level to compensate for the change of atmospheric pressure at a rate of -1 cm/mbar, is not associated with any ocean currents and hence is normally treated as an error to be removed from sea level observation. Linear regression and spectral transfer function analyses are applied to sea level and pressure to examine the validity of the IB effect. In regions outside the tropics, the regression coefficient is found to be consistently close to the theoretical value except for the regions of western boundary currents, where the mesoscale variability interferes with the IB effect. The spectral transfer function shows near IB response at periods from 20 to 300 days. The regression coefficient averaged over the regions poleward of 30 degrees is -0.84 +/- 0.29 cm/mbar (1 standard deviation). The deviation from -1 cm/mbar is shown to be caused primarily by the effect of wind forcing on sea level, based on a multivariate linear regression model involving both pressure and wind forcing. The regression coefficient for pressure resulting from the multivariate analysis is -0.96 +/- 0.32 cm/mbar. In the tropics the multivariate analysis fails because sea level in the tropics is primarily responding to remote wind forcing. However, after removing from the data the wind-forced sea level estimated by a dynamic model of the tropical Pacific, the pressure regression coefficient improves from -1.22 +/- 0.69 cm/mbar to -0.99 +/- 0.46 cm/mbar, clearly revealing an IB response. The result of the study suggests that with a proper removal of the effect of wind forcing the IB effect is valid in most of the open ocean at periods longer than 20 days and spatial scales larger than 500 km. RP FU, LL (reprint author), CALTECH,JET PROP LAB,MS 300-323,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 66 Z9 71 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 DEC 15 PY 1994 VL 99 IS C12 BP 24633 EP 24642 DI 10.1029/94JC01647 PG 10 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300017 ER PT J AU TSAOUSSI, LS KOBLINSKY, CJ AF TSAOUSSI, LS KOBLINSKY, CJ TI AN ERROR COVARIANCE MODEL FOR SEA-SURFACE TOPOGRAPHY AND VELOCITY DERIVED FROM TOPEX/POSEIDON ALTIMETRY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GLOBAL OCEAN TIDES; GEOSAT ALTIMETRY AB In order to facilitate the use of satellite altimeter-derived sea surface topography and velocity in oceanographic models, a methodology is presented for deriving the total error covariance and its geographic distribution from TOPEX/POSEIDON measurements. The model is formulated using a parametric model fit to the altimeter range observations. The topography and velocity are modeled with spherical harmonic expansions whose coefficients are found through optimal adjustment to the altimeter range residuals using Bayesian statistics. All other parameters, including the orbit, geoid, surface models, and range corrections are provided as unadjusted parameters. The maximum likelihood estimates and errors are derived from the probability density function of the altimeter range residuals conditioned with a priori information. Estimates of model errors for the unadjusted parameters are obtained from the TOPEX/POSEIDON postlaunch verification results and the error covariances for the orbit and the geoid, except for the ocean tides. The error in the ocean tides is modeled; first, as the difference between two global tide models and, second, as the correction to the present tide model, the correction derived from TOPEX/POSEIDON data. A formal error covariance propagation scheme is used to derive the total error. Our global total error estimate for the TOPEX/POSEIDON topography relative to the geoid for one 10-day period is found to be 11 cm RMS. When the error in the geoid is removed, thereby providing an estimate of the time dependent error, the uncertainty in the topography is 3.5 cm RMS. This level of accuracy is consistent with direct comparisons of TOPEX/POSEIDON altimeter heights with tide gauge measurements at 28 stations. In addition, the error correlation length scales are derived globally in both east-west and north-south directions, which should prove useful for data assimilation. The largest error correlation length scales are found in the tropics. Errors in the velocity field are smallest in midlatitude regions; they are less than 2 cm/s over most of the Southern Ocean. For both variables the largest errors are caused by uncertainty in the geoid. More accurate representations of the geoid await a dedicated geopotential satellite mission. Substantial improvements in the accuracy of ocean tide models are expected in the very near future from research with TOPEX/POSEIDON data. Consequently, estimates of the time dependent sea surface topography from TOPEX/POSEIDON could achieve a total uncertainty of less than 3 cm RMS. This level of accuracy from a spaceborne sensor represents a remarkable engineering achievement and a major contribution to ocean science. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP TSAOUSSI, LS (reprint author), HUGHES STX CORP,7701 GREENBELT RD,SUITE 400,GREENBELT,MD, USA. NR 26 TC 26 Z9 26 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 DEC 15 PY 1994 VL 99 IS C12 BP 24669 EP 24683 DI 10.1029/94JC01639 PG 15 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300020 ER PT J AU BUSALACCHI, AJ MCPHADEN, MJ PICAUT, J AF BUSALACCHI, AJ MCPHADEN, MJ PICAUT, J TI VARIABILITY IN EQUATORIAL PACIFIC SEA-SURFACE TOPOGRAPHY DURING THE VERIFICATION PHASE OF THE TOPEX/POSEIDON MISSION SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GEOSAT ALTIMETER DATA; TROPICAL PACIFIC; ROSSBY WAVES; EL-NINO; OCEAN; OSCILLATIONS; TIDES AB As part of the verification phase of the TOPEX/POSEIDON mission, 10-day gridded fields of altimeter data derived from TOPEX geophysical data records are compared with 10-day gridded fields of dynamic height derived from more than 60 moorings of the Tropical Ocean and Global Atmosphere-Tropical Atmosphere Ocean (TOGA-TAO) array in the equatorial Pacific Ocean. Access to TAO data in real time permits the first 500 days of the TOPEX/POSEIDON mission to be placed in the context of complementary, in situ measurements of surface winds, sea surface temperatures, and upper ocean thermal structure, as well as the time history of these variables prior to launch. Analysis of the space-time structure in the TOPEX and TAO surface topography data indicates sea level variability primarily due to equatorial Kelvin wave activity generated by intense wind bursts west of the date line in association with the 1991-1993 EI Ni ($) over tilde$$ no. Cross correlations between the two data sets are generally >0.7, with RMS differences <4 cm. However, for reasons not fully understood, correlations drop to <0.5 in certain regions off the equator in the eastern Pacific, and RMS differences can be >5 cm north of the equator in the central and eastern Pacific. C1 NOAA,PACIFIC MARINE ENVIRONM LAB,SEATTLE,WA 98115. ORSTOM,SURVEILLANCE TRANSOCEAN PACIFIQUE,NOUMEA,NEW CALEDONIA. RP BUSALACCHI, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,MAIL CODE 970,GREENBELT,MD 20771, USA. RI McPhaden, Michael/D-9799-2016 NR 35 TC 40 Z9 40 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 DEC 15 PY 1994 VL 99 IS C12 BP 24725 EP 24738 DI 10.1029/94JC01638 PG 14 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300024 ER PT J AU MOLINES, JM LEPROVOST, C LYARD, F RAY, RD SHUM, CK EANES, RJ AF MOLINES, JM LEPROVOST, C LYARD, F RAY, RD SHUM, CK EANES, RJ TI TIDAL CORRECTIONS IN THE TOPEX/POSEIDON GEOPHYSICAL-DATA RECORDS SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GLOBAL OCEAN TIDES; GEOSAT ALTIMETRY AB The aim of this paper is to give an assessment to TOPEX/POSEIDON data users of the two available oceanic tidal corrections, which are based on the Schwiderski model (SCH) and the Cartwright and nay model (Cn), respectively. Large instantaneous differences are observed between the two corrections, and use of either model may sometimes lead to inadequate understanding of the remaining oceanic signals. In this paper we give an objective comparison of SCH and Cn models and point out the major features of both models. Our methodology is applicable to the validating and testing of future tide models that will soon be appearing. C1 NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. UNIV TEXAS,CTR SPACE RES,AUSTIN,TX 78712. RP MOLINES, JM (reprint author), INST MECAN GRENOBLE,ECOULEMENTS GEOPHYS & IND LAB,BP 53X,F-38041 GRENOBLE,FRANCE. RI Ray, Richard/D-1034-2012 NR 17 TC 19 Z9 19 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 DEC 15 PY 1994 VL 99 IS C12 BP 24749 EP 24760 DI 10.1029/94JC01959 PG 12 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300026 ER PT J AU SCHRAMA, EJO RAY, RD AF SCHRAMA, EJO RAY, RD TI A PRELIMINARY TIDAL ANALYSIS OF TOPEX/POSEIDON ALTIMETRY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GLOBAL OCEAN TIDES; GEOSAT ALTIMETRY; ORBIT AB Approximately 12 months of data from the TOPEX/POSEIDON satellite altimeter mission are analyzed for the major short-period oceanic tides. A harmonic analysis is performed on data captured within bins defined on a deep-ocean grid, which, owing to tidal aliasing considerations, must have a relatively coarse spatial resolution. Our analysis is in terms of corrections to the Schwiderski and Cartwright-Ray models, and it confirms many of the Schwiderski differences previously reported by Cartwright and Ray. Our differences with respect to the Geosat-based Cartwright and Ray model form a sectorial pattern in Mt with high/low differences separated roughly 180 degrees in longitude. We suggest that these sectorial errors were most likely induced by Geosat's relatively large orbit error. Comparisons to independent data validate the improved TOPEX/POSEIDON solutions; in situ ''ground truth'' shows M(2) RMS differences of 4.10 cm (Schwiderski), 3.86 cm (Cartwright and Ray), 2.63 cm (this paper). Global rates of energy dissipation confirm earlier estimates for M(2), and show improved agreement with satellite tracking studies for K-1 and S-2. These preliminary exercises confirm that TOPEX/POSEIDON should result in a new generation of improved global tidal models. C1 NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. RP SCHRAMA, EJO (reprint author), DELFT UNIV TECHNOL,FAC GEODESY,THIJSSEWEG 11,2629 JA DELFT,NETHERLANDS. RI Ray, Richard/D-1034-2012 NR 32 TC 124 Z9 132 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24799 EP 24808 DI 10.1029/94JC01432 PG 10 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300029 ER PT J AU IMEL, DA AF IMEL, DA TI EVALUATION OF THE TOPEX/POSEIDON DUAL-FREQUENCY IONOSPHERE CORRECTION SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article AB The NASA altimeter on board TOPEX/POSEIDON exploits the difference in the delays of the Ku and C band radar pulses to estimate an ionosphere correction to the range measurement. The dependence of the ionosphere correction on ocean and satellite parameters is less than 1 cm. The standard deviation of the 1-s averaged ionosphere correction depends on the height of the ocean waves and ranges from 5 to 14 mm. The accuracy of the ionosphere correction is better than 1 cm at the 1 sigma confidence level. The ionosphere correction should be averaged over 140 km (20 s) along track in order to minimize its noise without sacrificing its accuracy. Ionosphere models must achieve an independent sample spacing of 900 km or less in order to allow a single-frequency altimeter to have an ionosphere correction comparable in accuracy to that of the NASA dual-frequency altimeter. RP IMEL, DA (reprint author), CALTECH,JET PROP LAB,MS 300-319,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 81 Z9 85 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24895 EP 24906 DI 10.1029/94JC01869 PG 12 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300035 ER PT J AU ZLOTNICKI, V AF ZLOTNICKI, V TI CORRELATED ENVIRONMENTAL CORRECTIONS IN TOPEX/POSEIDON, WITH A NOTE ON IONOSPHERIC ACCURACY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GEOSAT ALTIMETER DATA; SEA-STATE BIAS; LEVEL; TIDES AB Estimates of the effectiveness of an altimetric correction, and interpretation of sea level variability as a response to atmospheric forcing, both depend upon assuming that residual errors in altimetric corrections are uncorrelated among themselves and with residual sea level, or knowing the correlations. Not surprisingly, many corrections are highly correlated since they involve atmospheric properties and the ocean surface's response to them. The full corrections (including their geographically varying time mean values), show correlations between electromagnetic bias (mostly the height of wind waves) and either atmospheric pressure or water vapor of -40%, and between atmospheric pressure and water vapor of 28%. In the more commonly used collinear differences (after removal of the geographically varying time mean), atmospheric pressure and wave height show a -30% correlation, atmospheric pressure and water vapor a -10% correlation, both pressure and water vapor a 7% correlation with residual sea level, and a bit surprisingly, ionospheric electron content and wave height a 15% correlation. Only the ocean tide is totally uncorrelated with other corrections or residual sea level. The effectiveness of three ionospheric corrections (TOPEX dual-frequency, a smoothed version of the TOPEX dual-frequency, and Doppler orbitography and radiopositioning integrated by satellite (DORIS) is also evaluated in terms of their reduction in variance of residual sea level. Smooth (90-200 km along-track) versions of the dual-frequency altimeter ionosphere perform best both globally and within 20 degrees in latitude from the equator. The noise variance in the 1/s TOPEX ionospheric samples is similar to(11 mm)(2), about the same as noise in the DORIS-based correction; however, the latter has its error over scales of order 10(3) km. Within 20 degrees of the equator, the DORIS-based correction adds (14 mm)(2) to the residual sea level variance. RP ZLOTNICKI, V (reprint author), CALTECH,JET PROP LAB,MS 300-323,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 38 TC 23 Z9 24 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24907 EP 24914 DI 10.1029/94JC01646 PG 8 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300036 ER PT J AU RUF, CS KEIHM, SJ SUBRAMANYA, B JANSSEN, MA AF RUF, CS KEIHM, SJ SUBRAMANYA, B JANSSEN, MA TI TOPEX-POSEIDON MICROWAVE RADIOMETER PERFORMANCE AND IN-FLIGHT CALIBRATION SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID WATER; SSM/I AB Results of the in-flight calibration and performance evaluation campaign for the TOPEX/POSEIDON microwave radiometer (TMR) are presented. Intercomparisons are made between TMR and various sources of ground truth, including ground-based microwave water vapor radiometers, radiosondes, global climatological models, special sensor microwave imager data over the Amazon rain forest, and models of clear, calm, subpolar ocean regions. After correcting for preflight errors in the processing of thermal/vacuum data, relative channel offsets in the open ocean TMR brightness temperatures were noted at the approximate to 1 K level for the three TMR frequencies. Larger absolute offsets of 6-9 K over the rain forest indicated a approximate to 5% gain error in the three channel calibrations. This was corrected by adjusting the antenna pattern correction (APC) algorithm. A 10% scale error in the TMR path delay estimates, relative to coincident radiosondes, was corrected in part by the APC adjustment and in part by a 5% modification to the value assumed for the 22.235 GHz water vapor line strength in the path delay retrieval algorithm. After all in-flight corrections to the calibration, TMR global retrieval accuracy for the wet tropospheric range correction is estimated at 1.1 cm RMS with consistent performance under clear, cloudy, and windy conditions. C1 BALL CORP, PASADENA, CA USA. HUGHES STX, LANHAM, MD USA. CALTECH, JET PROP LAB, PASADENA, CA USA. RP PENN STATE UNIV, DEPT ELECT ENGN, UNIVERSITY PK, PA 16802 USA. RI Ruf, Christopher/I-9463-2012 NR 29 TC 55 Z9 55 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9275 EI 2169-9291 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24915 EP 24926 DI 10.1029/94JC00717 PG 12 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300037 ER PT J AU HAYNE, GS HANCOCK, DW PURDY, CL CALLAHAN, PS AF HAYNE, GS HANCOCK, DW PURDY, CL CALLAHAN, PS TI THE CORRECTIONS FOR SIGNIFICANT WAVE HEIGHT AND ATTITUDE EFFECTS IN THE TOPEX RADAR ALTIMETER SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID POSEIDON PROJECT AB The routine ground processing of data from the NASA radar altimeter of TOPEX/POSEIDON includes instrument corrections for the effects of significant wave height and attitude angle changes on the altimeter's estimates of range, backscattered power, and significant wave height. This paper describes how these instrument corrections were generated and how they are applied. Detailed waveform fitting to telemetered waveform samples is used to assess the effectiveness of the corrections. There are several altimeter hardware-caused small waveform departures from the model waveforms and these departures, designated waveform ''features,'' are described in detail. A consequence of the waveform features, and their positioning relationship to range rate, is that range data for ground tracks moving toward the equator may differ systematically by about a centimeter compared to range data for ground tracks moving away from the equator. The results and discussion are limited to side A of the redundant altimeter, as only side A has been operated on orbit. C1 CALTECH,JET PROP LAB,PASADENA,CA. RP HAYNE, GS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337, USA. NR 7 TC 34 Z9 37 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24941 EP 24955 DI 10.1029/94JC01777 PG 15 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300039 ER PT J AU RODRIGUEZ, E MARTIN, JM AF RODRIGUEZ, E MARTIN, JM TI ASSESSMENT OF THE TOPEX ALTIMETER PERFORMANCE USING WAVE-FORM RETRACKING SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GENERATED GRAVITY-WAVES; SURFACE ELEVATION; EQUILIBRIUM RANGE; RADAR ALTIMETER; HEIGHT; SPECTRUM; OCEAN AB To assess the accuracy of the TOPEX altimeter data, we have reprocessed the raw altimeter waveform data using more sophisticated algorithms than those implemented in the altimeter hardware. We discuss systematic contamination of the waveform which we have observed and its effect on very long wavelength errors. We conclude that these systematic errors are responsible for a very long wavelength error whose peak-to-peak magnitude for the Ku band altimeter is of the order of 1 cm. We also examine the ability of retracked data to reduce the repeat pass variance and correct for significant wave height (SWH) and acceleration dependent errors. We find that the ground postprocessing contains SWH dependent biases which depend on the altimeter fine height correction. RP RODRIGUEZ, E (reprint author), CALTECH,JET PROP LAB,MAIL STOP 300-319,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 20 TC 23 Z9 25 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24957 EP 24969 DI 10.1029/94JC02030 PG 13 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300040 ER PT J AU RODRIGUEZ, E MARTIN, JM AF RODRIGUEZ, E MARTIN, JM TI ESTIMATION OF THE ELECTROMAGNETIC BIAS FROM RETRACKED TOPEX DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA-STATE BIAS; SURFACE RANGE MEASUREMENTS; GEOSAT ALTIMETER; RADAR ALTIMETRY; SATELLITE; DEPENDENCE AB We examine the electromagnetic (EM) bias by using retracked TOPEX altimeter data. In contrast to previous studies, we use a parameterization of the EM bias which does not make stringent assumptions about the form of the correction or its global behavior. We fmd that the most effective single parameter correction uses the altimeter-estimated wind speed but that other parameterizations, using a wave age related parameter of significant wave height, may also significantly reduce the repeat pass variance. The different corrections are compared, and their improvement of the TOPEX height variance is quantified. RP RODRIGUEZ, E (reprint author), CALTECH,JET PROP LAB,MAIL STOP 300-319,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 27 TC 13 Z9 14 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 24971 EP 24979 DI 10.1029/94JC02029 PG 9 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300041 ER PT J AU CALLAHAN, PS MORRIS, CS HSIAO, SV AF CALLAHAN, PS MORRIS, CS HSIAO, SV TI COMPARISON OF TOPEX/POSEIDON SIGMA(0) AND SIGNIFICANT WAVE HEIGHT DISTRIBUTIONS TO GEOSAT SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID WIND-SPEED; ALTIMETER; SURFACE; BUOY; SEA AB Monthly Ku band sigma(0) and significant wave height (SWH) histograms from the NASA altimeter on the TOPEX/POSEIDON satellite are presented for January through June 1993 for three latitude bands between +/-60 degrees. The data are compared to distributions from the Geosat mission for the same months in 1987-1989. Generally, the distributions agree quite well, although there are some seasonal/hemispherical differences. The sigma(0) comparison reveals an overall bias between the two altimeters with the TOPEX sigma(0) higher by about 0.7 dB, which is consistent with algorithm improvements for TOPEX. The SWH distributions show strong hemispherical/seasonal changes. The seasonal/hemispherical. differences between TOPEX and Geosat are consistent for SWH and sigma(0). The joint distribution of sigma(0) and SWH is extremely stable from month to month. The typical SWH is independent of sigma(0) for sigma(0) greater than 11.3 dB. The minimum SWH grows exponentially with wind speed. This joint distribution may be useful for understanding electromagnetic bias in altimeter measurements. Finally, altimeter data are compared to buoy values from 21 overflights of the NASA verification site near Pt. Conception, California. Wave heights agree well with an RMS difference of only 0.2 m. Altimeter sigma(0) values are compared to buoy wind speeds. The results are consistent with the -0.7 dB sigma(0) offset from the histogram comparisons. RP CALLAHAN, PS (reprint author), CALTECH,JET PROP LAB,MS 300-319,PASADENA,CA 91109, USA. NR 19 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 25015 EP 25024 DI 10.1029/94JC01759 PG 10 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300045 ER PT J AU DELCROIX, T BOULANGER, JP MASIA, F MENKES, C AF DELCROIX, T BOULANGER, JP MASIA, F MENKES, C TI GEOSAT-DERIVED SEA-LEVEL AND SURFACE CURRENT ANOMALIES IN THE EQUATORIAL PACIFIC DURING THE 1986-1989 EL-NINO AND LA-NINA SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID BAROCLINIC OCEAN MOTIONS; FITTING DYNAMIC-MODELS; TROPICAL PACIFIC; ROSSBY WAVES; ALTIMETER DATA; WIND STRESS; VARIABILITY; KELVIN; TRANSPORTS; EVENT AB Equatorial wave dynamics are essential in most oceanic models for reproducing aspects of the El Nino-Southern Oscillation (ENSO) phenomenon. In this paper, observational evidence of first baroclinic equatorial Kelvin and first symmetric meridional Rossby waves is found in Geosat-derived sea level anomalies (SLA) and surface zonal current anomalies (ZCA) in the equatorial Pacific ocean during the 1986-1987 El Nino and the ensuing 1988-1989 La Nina. This was made possible after extensive quality control and specific processing of the recently improved Geosat geophysical data records pertaining to the 17-day Exact Repeat Mission. In particular, the processing was made so that the Geosat-derived ZCA best fit near-surface zonal currents from three equatorial moorings at 165 degrees E, 140 degrees W, and 110 degrees W. The Geosat-derived SLA and ZCA are decomposed into first baroclinic equatorial Kelvin and gravest Rossby modes. The emphasis is then put on the chronology of the ZCA at the equator where the currents are the most energetic and where Kelvin and first symmetric Rossby waves explain most of the variance in ZCA, in similar proportion. The 1986-1987 El Nino is mostly characterized by a strong downwelling Kelvin wave in December 1986, a series of downwelling Kelvin waves in March-October 1987, and a strong upwelling Rossby wave in March-September 1987. These waves are consistent with wind forcing, and ah give rise to notable eastward ZCA for almost an entire year. During the El Nino-La Nina transition period there is the occurrence of two downwelling Rossby waves originating from the eastern Pacific at times of favorable wind forcing. These Rossby waves switch the basin-wide ZCA from eastward to westward, terminating the warm event. Then, the 1988-1989 La Nina shows the generation of a series of upwelling Kelvin waves which are clearly identified in March/April and September/October 1988. These upwelling Kelvin waves are apparently related to the enhancement of the trade wind in the western half of the basin. These waves maintain the basin-wide westward ZCA for more than a year, although the ZCA is slightly reduced by a front of upwelling Rossby waves in phase with the normal seasonal cycle. The Kelvin wave forcing and sign of Kelvin wave contribution versus Rossby wave contribution to ZCA in the western Pacific are discussed, and we conclude that neither pleads in favor of the delayed action oscillator mechanism. C1 UNIV PARIS 06,ORSTOM,OCEANOG DYNAM & CLIMATOL LAB,PARIS,FRANCE. UNIV SPACE RES ASSOC,GODDARD SPACE FLIGHT CTR,GREENBELT,MD. RP DELCROIX, T (reprint author), ORSTOM,SURVEILLANCE TRANSOCEAN PACIFIQUE GRP,BP A5,NOUMEA,NEW CALEDONIA. RI Delcroix, Thierry/I-6103-2016; menkes, christophe/H-9085-2016 OI Delcroix, Thierry/0000-0002-8850-4865; menkes, christophe/0000-0002-1457-9696 NR 50 TC 72 Z9 72 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 25093 EP 25107 DI 10.1029/94JC02138 PG 15 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300051 ER PT J AU WANG, LP KOBLINSKY, CJ AF WANG, LP KOBLINSKY, CJ TI INFLUENCE OF MIDOCEAN RIDGES ON ROSSBY WAVES SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID NORTH-ATLANTIC; GENERATION; VARIABILITY AB Influence of mid-ocean ridges on Rossby wave activity is discussed in simple models. Ridges can influence Rossby waves in two ways, topographic scattering and mid-ocean local generation. It is found that both processes are rather sensitive to model parameters such as frequency, ridge height, and ridge width in both barotropic and baroclinic models. In the barotropic model, for certain model parameters there is perfect transmission of Rossby waves, while for some other model parameters the transmission is rather weak. In a two-layer model, if the frequency is not low enough, trapping of baroclinic signals around topography will occur. The mid-ocean ridge is generally not as efficient as the eastern boundary in generating barotropic waves except at high frequencies in a barotropic model. It is much more efficient than the eastern boundary in generating baroclinic waves when wind forcing has a very large zonal scale, while less efficient when wind forcing has a short zonal scale. RP WANG, LP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MAIL CODE 971,GREENBELT,MD 20771, USA. NR 15 TC 21 Z9 21 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 25143 EP 25153 DI 10.1029/94JC02374 PG 11 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300054 ER PT J AU HOOKER, SB BROWN, JW AF HOOKER, SB BROWN, JW TI WARM-CORE RING DYNAMICS DERIVED FROM SATELLITE IMAGERY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID VORTICES; MODEL; FLOW; 82B AB A reinterpretation of the life history of warm core ring 82-B is constructed from drifter trajectories, hydrographic profiles, and satellite-derived sea surface temperature fields. An analysis of the observations strongly suggests this ring is fundamentally a dipole structure for much of its existence. The dipole has unequal strength vortices, with the cyclone being the weaker component. Quantification of the dipole indicates the anticyclone is oval shaped and rotates at approximately 7.7 degrees per day, while the cyclone revolves around the anticyclone at about 14.5 degrees per day, yielding an orbit period of approximately 25 days for the cyclone. The elusive part of the dipole explanation is in interpreting its surface signature as a function of time, as the cyclone appears to disappear when in proximity to the steep continental slope. Vortex modeling suggests that when the weaker cyclonic eddy is placed close to a boundary, the cyclone is drawn into a filament as it is advected through the gap between the anticyclone and the boundary. This means the cyclone is either in a filamentation state or undergoing the straining associated with filamentation approximately three fourths of the time, which is in complete agreement with the satellite imagery. In addition, the 82-B dipole configuration is sufficiently robust to survive continuous interaction with the continental slope and the onset of a Gulf Stream interaction. Although only warm core ring 82-B is analyzed in detail (and found to be a vortex pair), dipole configurations are found in the warm core ring 81-F time series as well. C1 UNIV MIAMI,ROSENSTIEL SCH MARINE & ATMOSPHER SCI,MIAMI,FL 33149. RP HOOKER, SB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 971,GREENBELT,MD 20771, USA. RI Hooker, Stanford/E-2162-2012 NR 24 TC 15 Z9 15 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 25181 EP 25194 DI 10.1029/94JC02171 PG 14 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300057 ER PT J AU JIN, ZH STAMNES, K WEEKS, WF TSAY, SC AF JIN, ZH STAMNES, K WEEKS, WF TSAY, SC TI THE EFFECT OF SEA-ICE ON THE SOLAR-ENERGY BUDGET IN THE ATMOSPHERE SEA-ICE OCEAN SYSTEM - A MODEL STUDY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ARCTIC STRATUS CLOUDS; RADIATIVE-TRANSFER; MULTIPLE-SCATTERING; OPTICAL-PROPERTIES; SPECTRAL ALBEDO; LIGHT; TRANSMISSION; ABSORPTION; GROWTH; SNOW AB A coupled one-dimensional multilayer and multistream radiative transfer model has been developed and applied to the study of radiative interactions in the atmosphere, sea ice, and ocean system. The consistent solution of the radiative transfer equation in this coupled system automatically takes into account the refraction and reflection at the air-ice interface and allows flexibility in choice of stream numbers. The solar radiation spectrum (0.25 mu m-4.0 mu m) is divided into 24 spectral bands to account adequately for gaseous absorption in the atmosphere. The effects of ice property changes, including salinity and density variations, as well as of melt ponds and snow cover variations over the ice on the solar energy distribution in the entire system have been studied quantitatively. The results show that for bare ice it is the scattering, determined by air bubbles and brine pockets, in just a few centimeters of the top layer of the ice that plays the most important role in the solar energy absorption and partitioning in the entire system. Ice thickness is important to the energy distribution only when the ice is thin, while the absorption in the atmosphere is not sensitive to ice thickness variations, nor is the total absorption in the entire system once the ice thickness exceeds about 70 cm. The presence of clouds moderates all the sensitivities of the absorptive amounts in each layer to the variations in the ice properties and ice thickness. Comparisons with observational spectral albedo values for two simple ice types are also presented. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP JIN, ZH (reprint author), UNIV ALASKA,INST GEOPHYS,903 KOYUKUK DR,POB 757320,FAIRBANKS,AK 99775, USA. RI Tsay, Si-Chee/J-1147-2014 NR 43 TC 54 Z9 57 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-OCEANS JI J. Geophys. Res.-Oceans PD DEC 15 PY 1994 VL 99 IS C12 BP 25281 EP 25294 DI 10.1029/94JC02426 PG 14 WC Oceanography SC Oceanography GA PX773 UT WOS:A1994PX77300063 ER PT J AU CAHALAN, RF RIDGWAY, W WISCOMBE, WJ GOLLMER, S HARSHVARDHAN AF CAHALAN, RF RIDGWAY, W WISCOMBE, WJ GOLLMER, S HARSHVARDHAN TI INDEPENDENT PIXEL AND MONTE-CARLO ESTIMATES OF STRATOCUMULUS ALBEDO SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID SHAPED OPTICAL MEDIA; RADIATIVE-TRANSFER; CLOUDY ATMOSPHERES; SCATTERING; SPECTRA; NUMBER AB Monte Carlo radiative transfer methods are employed here to estimate the plane-parallel albedo bias for marine stratocumulus clouds. This is the bias in estimates of the mesoscale-average albedo, which arises from the assumption that cloud liquid water is uniformly distributed. The authors compare such estimates with those based on a more realistic distribution generated from a fractal model of marine stratocumulus clouds belonging to the class of ''bounded cascade'' models. In this model the cloud top and base are fixed, so that all variations in cloud shape are ignored. The model generates random variations in liquid water along a single horizontal direction, forming fractal cloud streets while conserving the total liquid water in the cloud field. The model reproduces the mean, variance, and skewness of the vertically integrated cloud liquid water, as well as its observed wavenumber spectrum, which is approximately a power law. The Monte Carlo method keeps track of the three-dimensional paths solar photons take through the cloud field, using a vectorized implementation of a direct technique. The simplifications in the cloud field studied here allow the computations to be accelerated. The Monte Carlo results are compared to those of the independent pixel approximation, which neglects net horizontal photon transport. Differences between the Monte Carlo and independent pixel estimates of the mesoscale-average albedo are on the order of 1% for conservative scattering, while the plane-parallel bias itself is an order of magnitude larger. As cloud absorption increases, the independent pixel approximation agrees even more closely with the Monte Carlo estimates. This result holds for a wide range of sun angles and aspect ratios. Thus, horizontal photon transport can be safely neglected in estimates of the area-average flux for such cloud models. This result relies on the rapid falloff of the wavenumber spectrum of stratocumulus, which ensures that the smaller-scale variability, where the radiative transfer is more three-dimensional, contributes less to the plane-parallel albedo bias than the larger scales, which are more variable. The lack of significant three-dimensional effects also relies on the assumption of a relatively simple geometry. Even with these assumptions, the independent pixel approximation is accurate only for fluxes avenged over large horizontal areas, many photon mean free paths in diameter, and not for local radiance values, which depend strongly on the interaction between neighboring cloud elements. C1 PURDUE UNIV,DEPT EARTH & ATMOSPHER SCI,LAFAYETTE,IN. RP CAHALAN, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. RI Cahalan, Robert/E-3462-2012; Wiscombe, Warren/D-4665-2012 OI Cahalan, Robert/0000-0001-9724-1270; Wiscombe, Warren/0000-0001-6844-9849 NR 37 TC 188 Z9 192 U1 0 U2 8 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD DEC 15 PY 1994 VL 51 IS 24 BP 3776 EP 3790 DI 10.1175/1520-0469(1994)051<3776:IPAMCE>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QA885 UT WOS:A1994QA88500014 ER PT J AU NORTON, AJ CHAKRABARTY, D COE, MJ EVERALL, C FINGER, MH PRINCE, TA ROCHE, P STOLLBERG, MT WILSON, RB AF NORTON, AJ CHAKRABARTY, D COE, MJ EVERALL, C FINGER, MH PRINCE, TA ROCHE, P STOLLBERG, MT WILSON, RB TI MULTIWAVELENGTH OBSERVATIONS OF THE BE STAR X-RAY BINARY EX02030+375 DURING OUTBURST SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE BINARIES, CLOSE; CIRCUMSTELLAR MATTER; STARS, INDIVIDUAL, EXO2030+375 STARS, NEUTRON; INFRARED, STARS; X-RAYS, STARS ID LUMINOSITY DEPENDENCE; PULSAR EXO-2030+375; WAVELENGTH DEPENDENCE; EXTINCTION LAW; POLARIZATION; EMISSION; POLARIMETRY; COUNTERPART AB We present the results from a campaign to monitor the behaviour of the Be star/X-ray binary EXO2030+375 during an X-ray outburst. The BATSE all-sky monitor on board the Compton Gamma-Ray Observatory satellite regularly detects pulsed emission from EXO2030+375 when the neutron star is near periastron. Ground-based optical spectroscopic data plus infrared photometric and polarimetric data were obtained simultaneously with these X-ray data during a typical outburst in 1993 June/July. Despite an increase in the pulsed X-ray flux by an order of magnitude, neither the infrared luminosity nor the equivalent width, strength or profile of the Ha emission line showed any significant, correlated changes. We conclude that (i) reprocessing of the X-ray flux in the Be star circumstellar envelope, (ii) gravitational disruption of that envelope by the neutron star and (iii) enhanced emission from an HII region formed around the neutron star are all minimal effects and below our detection threshold. We have also detected significant linear polarization in the infrared flux from EXO2030+375, and we discuss whether or not some fraction of this is intrinsic to the source. C1 CALTECH,PALOMAR OBSERV,PASADENA,CA 91125. CALTECH,SPACE RADIAT LAB 220-47,PASADENA,CA 91125. UNIV SOUTHAMPTON,DEPT PHYS,ASTRON & SPACE PHYS GRP,SOUTHAMPTON SO9 5NH,HANTS,ENGLAND. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35809. RP NORTON, AJ (reprint author), OPEN UNIV,DEPT PHYS,WALTON HALL,MILTON KEYNES MK7 6AA,BUCKS,ENGLAND. NR 36 TC 18 Z9 19 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 DEC 15 PY 1994 VL 271 IS 4 BP 981 EP 992 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PX622 UT WOS:A1994PX62200019 ER PT J AU HURLEY, K DINGUS, BL MUKHERJEE, R SREEKUMAR, P KOUVELIOTOU, C MEEGAN, C FISHMAN, GJ BAND, D FORD, L BERTSCH, D CLINE, T FICHTEL, C HARTMAN, R HUNTER, S THOMPSON, DJ KANBACH, G MAYERHASSELWANDER, H VONMONTIGNY, C SOMMER, M LIN, Y NOLAN, P MICHELSON, P KNIFFEN, D MATTOX, J SCHNEID, E BOER, M NIEL, M AF HURLEY, K DINGUS, BL MUKHERJEE, R SREEKUMAR, P KOUVELIOTOU, C MEEGAN, C FISHMAN, GJ BAND, D FORD, L BERTSCH, D CLINE, T FICHTEL, C HARTMAN, R HUNTER, S THOMPSON, DJ KANBACH, G MAYERHASSELWANDER, H VONMONTIGNY, C SOMMER, M LIN, Y NOLAN, P MICHELSON, P KNIFFEN, D MATTOX, J SCHNEID, E BOER, M NIEL, M TI DETECTION OF A GAMMA-RAY BURST OF VERY LONG-DURATION AND VERY-HIGH-ENERGY SO NATURE LA English DT Article ID EGRET AB ALTHOUGH gamma-ray bursts (GRBs) have been known for more than 20 years, their origin remains mysterious(1). Suggestions have ranged from nearby colliding comets(2) to merging neutron stars at cosmological distances(3). The lack of any counterpart at wavelengths other than X-rays and gamma-rays has posed a major problem in identifying the source of GRBs(4). Although in principle the distribution of energies among the burst photons, as well as their light curves, may be used to constrain the potential sources, this has proved difficult in practice(5). Here we present the observation of a particularly energetic burst with a duration of 90 minutes, which includes the detection of an 18-GeV photon. For comparison, typical GRBs emit photons in the energy range between a few keV and a few tens of MeV, and last a few tens of seconds(6,7). The extended nature of this burst holds out the hope that there will be opportunities for telescopes operating at other wavelengths to detect a GRB source white it is still active, thus providing further constraints on the source's identity and properties. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,SAN DIEGO,CA 92093. MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. STANFORD UNIV,HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. USRA,COMPTON OBSERV SCI SUPPORT CTR,WASHINGTON,DC. NORTHRUP GRUMMAN CORP,BETHPAGE,NY 11714. CTR ETUD SPATIALE RAYONNEMENTS,F-31029 TOULOUSE,FRANCE. RP HURLEY, K (reprint author), UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720, USA. RI Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; Nolan, Patrick/A-5582-2009 OI Thompson, David/0000-0001-5217-9135; NR 21 TC 476 Z9 487 U1 0 U2 10 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD DEC 15 PY 1994 VL 372 IS 6507 BP 652 EP 654 DI 10.1038/372652a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PX307 UT WOS:A1994PX30700078 ER PT J AU ROMANEK, CS GRADY, MM WRIGHT, IP MITTLEFEHLDT, DW SOCKI, RA PILLINGER, CT GIBSON, EK AF ROMANEK, CS GRADY, MM WRIGHT, IP MITTLEFEHLDT, DW SOCKI, RA PILLINGER, CT GIBSON, EK TI RECORD OF FLUID-ROCK INTERACTIONS ON MARS FROM THE METEORITE ALH84001 SO NATURE LA English DT Article ID ISOTOPE FRACTIONATIONS; STABLE ISOTOPES; SNC METEORITES; CARBON-DIOXIDE; OXYGEN; CALCITE; EVOLUTION AB ALLAN HILLS (ALH) 84001 is the most recently recognized(1) member of a suite of meteorites-the SNCs-that almost certainly originated on Mars(2). Several factors distinguish ALH84001 from the other SNC meteorites. Preliminary studies(3,4) suggest that it may be older than other martian meteorites. Moreover, it contains abundant, zoned domains of calcium-iron-magnesium carbonate that are indigenous to the sample(1) and thus may hold important clues regarding near-surface processes on Mars and the evolution of the martian atmosphere. We report here analyses of the carbon and oxygen stable-isotope Compositions of the carbonates that place constraints on their formation conditions. Our results imply the presence of at least two chemically distinct carbonates-one Ca,Fe-rich, the other Mg-rich-that are enriched in C-13 relative to terrestrial carbonates (delta(13)C approximate to + 41%parts per thousand), consistent with martian atmospheric CO2 as the carbon source. The oxygen isotope compositions of the carbonates indicate that they precipitated from a low-temperature fluid in the martian crust. Combined with textural and bulk geochemical considerations, the isotope data suggest that carbonate deposition took place in an open-system environment in which the ambient temperature fluctuated. C1 BRITISH MUSEUM NAT HIST,DEPT MINERAL,LONDON SW7 5BD,ENGLAND. OPEN UNIV,DEPT EARTH SCI,PLANETARY SCI UNIT,MILTON KEYNES MK7 6AA,BUCKS,ENGLAND. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP ROMANEK, CS (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH SN4,HOUSTON,TX 77058, USA. OI Grady, Monica/0000-0002-4055-533X NR 25 TC 186 Z9 188 U1 1 U2 15 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD DEC 15 PY 1994 VL 372 IS 6507 BP 655 EP 657 DI 10.1038/372655a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PX307 UT WOS:A1994PX30700079 PM 7990956 ER PT J AU ABDELDAYEM, H WITHEROW, WK SHIELDS, A PENN, B FRAZIER, DO MOGHBEL, M VENKATESWARLU, P SEKHAR, PC GEORGE, MC AF ABDELDAYEM, H WITHEROW, WK SHIELDS, A PENN, B FRAZIER, DO MOGHBEL, M VENKATESWARLU, P SEKHAR, PC GEORGE, MC TI CONTINUOUS-WAVE LASER-BEAM FANNING IN ORGANIC SOLUTIONS - A NOVEL PHENOMENON SO OPTICS LETTERS LA English DT Article ID NONLINEARITIES; DIFFRACTION; MEDIA; LIGHT AB If a low-power cw Ar+ laser beam (similar to 50 mW) is sent horizontally and focused on the entrance side of a cuvette containing an absorptive solution, the beam fans into the lower half of the cuvette instead of propagating through and forming self-phase-modulation fringes. We call this phenomenon self-beam fanning, which has been observed in several organic solutions. We present here several experimental results and a descriptive model of the phenomenon. C1 ALABAMA A&M UNIV,DEPT PHYS,NORMAL,AL 35762. UNIV W FLORIDA,DEPT PHYS,PENSACOLA,FL 32514. RP ABDELDAYEM, H (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES76,BLDG 4481,HUNTSVILLE,AL 35812, USA. NR 11 TC 4 Z9 4 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD DEC 15 PY 1994 VL 19 IS 24 BP 2068 EP 2070 DI 10.1364/OL.19.002068 PG 3 WC Optics SC Optics GA QA175 UT WOS:A1994QA17500008 PM 19855742 ER PT J AU NOEVER, D BASKARAN, S SCHUSTER, P AF NOEVER, D BASKARAN, S SCHUSTER, P TI UNDERSTANDING GENETIC ALGORITHM DYNAMICS USING HARVESTING STRATEGIES SO PHYSICA D LA English DT Article AB The genetic algorithm (GA) finds optimal solutions over complex fitness landscapes using a method developed in analogy to genetic laws and natural selection. The method essentially operates by optimizing the tradeoff between exploring new points in the search space and exploiting previous information discovered thus far. In this tradeoff, an understanding of the internal GA dynamics, how exactly the GA arrives at an optimum solution, remains somewhat mysterious. Harvesting strategies are introduced here to parameterize the GA's dynamical behavior of elevating sub-threshold solutions toward optimum. The method of harvesting balances the competing aims of population diversity counterweighted against rapid convergence toward the optimum solution. The work establishes that: (1) an upper bound on the fitness ratio exists, above which harvesting becomes too disruptive to the population diversity; (2) analytical conditions for considering elevation within the genetic algorithm are a specific case of logistic growth; and (3) explicit relations exist for the maximum yield and maximum harvestable fraction for 2-stage, 3-stage and finally n-stage harvesting strategies as a function of fitness ratio. Simple expressions for GA time complexity between harvesting steps are presented. C1 INST MOLEK BIOTECHNOL EV,O-7745 JENA,GERMANY. RP NOEVER, D (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,ES-76,HUNTSVILLE,AL 35812, USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2789 J9 PHYSICA D JI Physica D PD DEC 15 PY 1994 VL 79 IS 2-4 BP 132 EP 145 PG 14 WC Mathematics, Applied; Physics, Multidisciplinary; Physics, Mathematical SC Mathematics; Physics GA PY379 UT WOS:A1994PY37900002 ER PT J AU MAIA, MD SILVA, GS AF MAIA, MD SILVA, GS TI GEOMETRICAL CONSTRAINTS ON THE COSMOLOGICAL CONSTANT SO PHYSICAL REVIEW D LA English DT Article ID PERTURBATIONS C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP MAIA, MD (reprint author), UNIV BRASILIA,DEPT MATEMAT,BR-70910900 BRASILIA,DF,BRAZIL. OI maia, marcos/0000-0003-0094-7686 NR 19 TC 23 Z9 24 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 DEC 15 PY 1994 VL 50 IS 12 BP 7233 EP 7238 DI 10.1103/PhysRevD.50.7233 PG 6 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PY499 UT WOS:A1994PY49900014 ER PT J AU STASIK, MC PETTIT, FS MEIER, GH ASHARY, A SMIALEK, JL AF STASIK, MC PETTIT, FS MEIER, GH ASHARY, A SMIALEK, JL TI EFFECTS OF REACTIVE ELEMENT ADDITIONS AND SULFUR REMOVAL ON THE OXIDATION BEHAVIOR OF FECRAL ALLOYS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID OXIDE SCALE ADHERENCE; CR-AL ALLOYS C1 PRAXAIR,INDIANAPOLIS,IN 46224. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP STASIK, MC (reprint author), UNIV PITTSBURGH,DEPT MAT SCI & ENGN,PITTSBURGH,PA 15261, USA. NR 18 TC 32 Z9 32 U1 1 U2 7 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 DEC 15 PY 1994 VL 31 IS 12 BP 1645 EP 1650 DI 10.1016/0956-716X(94)90457-X PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA PJ362 UT WOS:A1994PJ36200008 ER PT J AU MEARINI, GT KRAINSKY, IL WANG, YX DAYTON, JA RAMESHAM, R ROSE, MF AF MEARINI, GT KRAINSKY, IL WANG, YX DAYTON, JA RAMESHAM, R ROSE, MF TI FABRICATION OF AN ELECTRON MULTIPLIER UTILIZING DIAMOND FILMS SO THIN SOLID FILMS LA English DT Article DE CHEMICAL VAPOR DEPOSITION; DIAMOND; ELECTRONIC DEVICES; SECONDARY ELECTRON EMISSION ID HYDROGEN AB High secondary electron yields (sigma = 14-27) from polycrystalline diamond films on Mo substrates have been reported previously. We observed that continuous exposure to an electron beam degraded the secondary yield in vacuum as a function of fluence owing to a loss of surface hydrogen. However, the hydrogen partial pressure could be adjusted such that the high secondary yield remained stable during beam exposure. We have constructed a prototype electron multiplier using these diamond films for use in ultrahigh vacuum. A gain of 0.9 x 10(5) has been measured in a d.c. mode. Palladium, titanium and aluminum nitride have been studied for possible dynode substrate materials which might eliminate the need for hydrogen during operation. Total secondary yields as high as 50 were measured from diamond on palladium and sigma was stable at 25 during heating at 700 K in vacuum. Raman spectroscopy and scanning electron microscopy showed that variations in sigma from diamond films on Pd were due to differing concentrations of non-diamond carbon. C1 CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. AUBURN UNIV,AUBURN,AL 36849. RP MEARINI, GT (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 8 TC 25 Z9 26 U1 0 U2 3 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 DEC 15 PY 1994 VL 253 IS 1-2 BP 151 EP 156 DI 10.1016/0040-6090(94)90311-5 PG 6 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA PX356 UT WOS:A1994PX35600028 ER PT J AU JAWORSKE, DA AF JAWORSKE, DA TI EMITTANCE CHARACTERIZATION OF THERMAL CONTROL PAINTS, COATINGS AND SURFACES USING A CALORIMETRIC TECHNIQUE SO THIN SOLID FILMS LA English DT Article DE OPTICAL PROPERTIES AB Thermal control surfaces are used in every spacecraft thermal management system to dissipate heat through radiant heat transfer. This paper describes the thermal performance of several thermal control paints, coatings, and surfaces, as characterized by a calorimetric vacuum emissometer. The emissometer is designed to measure the functional emittance of a surface based on heat transfer from an underlying substrate to the surface and from the surface or near surface to a surrounding cold wall. Emittance measurements were made between 200 and 350 K. Perished aluminum, used here as a standard, was found to have a total hemispherical emittance of 0.06, as expected. A velvet black paint, also used here as a standard, was found to have an emittance of 0.94 at room temperature. Other surfaces of interest included a polyurethane-based black paint designated Z-306, a highly polished 316L stainless steel, and an atomic oxygen beam-textured carbon-carbon composite. RP JAWORSKE, DA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 13 TC 4 Z9 4 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 DEC 15 PY 1994 VL 253 IS 1-2 BP 233 EP 237 DI 10.1016/0040-6090(94)90326-3 PG 5 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA PX356 UT WOS:A1994PX35600043 ER PT J AU SMIALEK, JL JAYNE, DT SCHAEFFER, JC MURPHY, WH AF SMIALEK, JL JAYNE, DT SCHAEFFER, JC MURPHY, WH TI EFFECTS OF HYDROGEN ANNEALING, SULFUR SEGREGATION AND DIFFUSION ON THE CYCLIC OXIDATION RESISTANCE OF SUPERALLOYS - A REVIEW SO THIN SOLID FILMS LA English DT Article DE ADHESION; OXIDATION; SULFUR; SURFACE SEGREGATION ID OXIDE SCALE ADHERENCE; NICKEL; ELEMENTS; ADHESION; SURFACE; ALLOYS AB This review is based on the phenomenon of improved oxide scale adhesion for desulfurized superalloys. The proposed adhesion mechanism involves sulfur interfacial segregation and scale-metal bond weakening. Sulfur surface segregation on superalloys is examined as a function of temperature and sulfur content, and is related to the classical behaviour predicted by the McLean isotherm. Effective desulfurization to less than 1 ppmw can be accomplished by hydrogen annealing and is described by sulfur diffusion kinetics in nickel. Hydrogen annealing results in excellent cyclic oxidation resistance for a number of advanced superalloys. The concept of a critical sulfur content is discussed in terms of practical annealing conditions and section thicknesses. C1 CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. GE CO,AIRCRAFT ENGINES,CINCINNATI,OH 45215. RP SMIALEK, JL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 25 TC 115 Z9 120 U1 2 U2 15 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 DEC 15 PY 1994 VL 253 IS 1-2 BP 285 EP 292 DI 10.1016/0040-6090(94)90335-2 PG 8 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA PX356 UT WOS:A1994PX35600052 ER PT J AU SMOOT, GF TENORIO, L BANDAY, AJ KOGUT, A WRIGHT, EL HINSHAW, G BENNETT, CL AF SMOOT, GF TENORIO, L BANDAY, AJ KOGUT, A WRIGHT, EL HINSHAW, G BENNETT, CL TI STATISTICS AND TOPOLOGY OF THE COBE DIFFERENTIAL MICROWAVE RADIOMETER FIRST-YEAR SKY MAPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS; LARGE-SCALE STRUCTURE OF UNIVERSE; METHODS, STATISTICAL ID INFLATIONARY UNIVERSE; COSMIC STRUCTURE; FLUCTUATIONS; PERTURBATIONS; ANISOTROPY; TEXTURE AB We use statistical and topological quantities to test the COBE DMR first-year sky maps against the hypothesis that the observed temperature fluctuations reflect Gaussian initial density perturbations with random phases. Recent papers discuss specific quantities as discriminators between Gaussian and non-Gaussian behavior, but the treatment of instrumental noise on the data is largely ignored. The presence of noise in the data biases many statistical quantities in a manner dependent on both the noise properties and the unknown cosmic microwave background temperature field. Appropriate weighting schemes can minimize this effect, but it cannot be completely eliminated. Analytic expressions are presented for these biases, and Monte Carlo simulations are used to assess the best strategy for determining cosmologically interesting information from noisy data. The genus is a robust discriminator that can be used to estimate the power-law quadrupole-normalized amplitude, Q(rms-PS) independently of the two-point correlation function. The genus of the DMR data is consistent with Gaussian initial fluctuations with Q(rms-PS) = (15.7 +/- 2.2) - (6.6 +/- 0.3)(n - 1) mu K, where n is the power-law index. Fitting the rms temperature variations at various smoothing angles gives Q(rms-PS) = 13.2 +/- 2.5 mu K and n = 1.7(-0.6)(+0.3). While consistent with Gaussian fluctuations, the first year data are only sufficient to rule out strongly non-Gaussian distributions of fluctuations. C1 UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP SMOOT, GF (reprint author), UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,SPACE SCI LAB,BLDG 50-351,BERKELEY,CA 94720, USA. RI Kogut, Alan/D-6293-2012 NR 43 TC 58 Z9 58 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 1994 VL 437 IS 1 BP 1 EP 11 DI 10.1086/174970 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PW003 UT WOS:A1994PW00300001 ER PT J AU BHATTACHARYA, D THE, LS KURFESS, JD CLAYTON, DD GEHRELS, N LEISING, MD GRABELSKY, DA JOHNSON, WN JUNG, GV KINZER, RL PURCELL, WR STRICKMAN, MS ULMER, MP AF BHATTACHARYA, D THE, LS KURFESS, JD CLAYTON, DD GEHRELS, N LEISING, MD GRABELSKY, DA JOHNSON, WN JUNG, GV KINZER, RL PURCELL, WR STRICKMAN, MS ULMER, MP TI GAMMA-RAY OBSERVATIONS OF NGC-253 AND M82 WITH OSSE SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, STARBURST; GALAXIES, INDIVIDUAL (NGC 253, M82); GAMMA RAYS, OBSERVATIONS; RADIATION MECHANISMS, NONTHERMAL ID SCINTILLATION SPECTROMETER EXPERIMENT; STARBURST GALAXY M82; X-RAY; I SUPERNOVAE; LIGHT CURVES; EMISSION; SN-1987A; NGC-253; RADIO; SAMPLE AB Gamma-ray observations of the nearby starburst galaxies NGC 253 and M82 over the energy range (0.05-10) MeV have been obtained with the OSSE spectrometer on the Compton Gamma-Ray Observatory. The priority of these galaxies as OSSE targets had been established on the grounds that the average supernova rate may be high in starbursts as indicated by infrared and radio observations, and at distances of similar to 3 MPc a significant chance of supernova gamma-ray line detection exists. NGC 253 was detected in continuum emission up to 165 keV with a total significance of 4.4 sigma and an estimated luminosity of 3 x 10(40) ergs s(-1). The spectrum is best fit by a power law of photon index similar to 2.5. We consider the possible contribution of different emission mechanisms, including inverse Compton scattering, bremsstralung, discrete sources, and Type Ia/Ib supernova continuum to the measured flux. No significant continuum flux was observed from M82. A search for the gamma-ray line from the decay of the most abundant radioactive element produced in supernovae (Ni-56 --> (CO)-C-56 --> Fe-56) yielded no significant detection: the 3 sigma upper limits to the line fluxes at 0.158, 0.812, 0.847, and 1.238 MeV for both galaxies are obtained. C1 CLEMSON UNIV,DEPT PHYS & ASTRON,CLEMSON,SC 29634. USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NORTHWESTERN UNIV,DEPT PHYS & ASTRON,EVANSTON,IL 60208. UNIV SPACE RES ASSOC,WASHINGTON,DC 20024. RP BHATTACHARYA, D (reprint author), UNIV CALIF RIVERSIDE,INST GEOPHYS & PLANETARY PHYS,RIVERSIDE,CA 92521, USA. RI Gehrels, Neil/D-2971-2012; Johnson, Neil/G-3309-2014 NR 43 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 1994 VL 437 IS 1 BP 173 EP 178 DI 10.1086/174985 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PW003 UT WOS:A1994PW00300016 ER PT J AU SPAANS, M TIELENS, AGGM VANDISHOECK, EF BAKES, ELO AF SPAANS, M TIELENS, AGGM VANDISHOECK, EF BAKES, ELO TI PHOTON-DOMINATED REGIONS AROUND COOL STARS - THE EFFECTS OF THE COLOR TEMPERATURE OF THE RADIATION-FIELD SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; DUST, EXTINCTION; INFRARED, ISM, LINES AND BANDS; MOLECULAR PROCESSES; RADIATION MECHANISMS, THERMAL ID CLUMPY PHOTODISSOCIATION REGIONS; FINE-STRUCTURE TRANSITIONS; INTERSTELLAR GAS; STRUCTURE EXCITATION; MOLECULAR-HYDROGEN; LINE EMISSION; PAH MOLECULES; CLOUDS; COLLISIONS; GRAINS AB We have investigated the influence of the color temperature of the illuminating radiation field on the chemical and thermal structure of photon-dominated regions (PDRs). We present the results of a study of the photoelectric efficiency of heating by large molecules such as polycyclic aromatic hydrocarbons and very small grains for radiation fields characterized by different effective temperatures. We show that the efficiency for cooler (T-eff approximate to 6000-10,000 K) stars is at most an order of magnitude smaller than that for hotter (T-eff approximate to 20,000-30,000 K) stars. While cooler radiation fields result in less ultraviolet photons capable of heating, the efficiency per absorbed photon is higher, because the grains become less positively charged. We also present detailed calculations of the chemistry and thermal balance for generic PDRs (n(0) approximate to 10(3), G(0) approximate to 10(3)). For cooler radiation fields, the H/H-2 and C+/C/CO transition layers shift toward the surface of the PDR, because fewer photons are available to photodissociate H-2 and CO and to ionize C. The dominant cooling lines are the [C II] 158 mu m and the [O I] 63 mu m lines for the hotter radiation fields, but cooling by CO becomes dominant for a color temperature of 6000 K or lower. The [C II]/CO and [O I]/CO ratios are found to be very good diagnostics for the color temperature of the radiation field. C1 NASA,AMES RES CTR,THEORET STUDIES BRANCH MS 2453,MOFFETT FIELD,CA 94035. PRINCETON UNIV OBSERV,PRINCETON,NJ 08544. RP SPAANS, M (reprint author), STERREWACHT LEIDEN,POB 9513,2300 RA LEIDEN,NETHERLANDS. NR 54 TC 64 Z9 65 U1 2 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 1994 VL 437 IS 1 BP 270 EP 280 DI 10.1086/174994 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PW003 UT WOS:A1994PW00300025 ER PT J AU BACHILLER, R TEREBEY, S JARRETT, T MARTINPINTADO, J BEICHMAN, CA VANBUREN, D AF BACHILLER, R TEREBEY, S JARRETT, T MARTINPINTADO, J BEICHMAN, CA VANBUREN, D TI SHOCKED MOLECULAR GAS AROUND THE EXTREMELY YOUNG SOURCE IRAS-03282+3035 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (IRAS 03282 + 3035); ISM, JETS AND OUTFLOWS; ISM, MOLECULES; SHOCK WAVES; STARS, FORMATION; STARS, PRE-MAIN-SEQUENCE ID CARBON-MONOXIDE EMISSION; L1157 DARK CLOUD; SIO EMISSION; INFRARED-EMISSION; BIPOLAR OUTFLOW; EXCITING SOURCE; LINE EMISSION; STELLAR JET; HH 7-11; HYDROGEN AB We present observations of the shock tracers H-2 and SiO around the young stellar object IRAS 03282+/-3035. This unusual low-luminosity (L approximate to 2 L(circle dot) ) source drives a strong highly collimated CO outflow, and it is one of the youngest stellar objects known so far. The near-infrared H-2 emission, tracing 2000 K gas, comes from extremely high velocity CO bullets along the axis of the blueshifted lobe of the outflow. The millimeter SiO emission, tracing roughly 100 K gas, arises from lower velocity material at the end of the outflow lobe. The lack of high-temperature and high-velocity gas at the end of the outflow lobe indicates there is no hot bow shock at the outflow termination. In the context of current jet models this appears to rule out a bow shock driven by a steady state jet. Possible explanations for the structure include a time-dependent jet or a jet dominated by turbulent entrainment. C1 INFRARED PROC & ANAL CTR, JET PROPULS LAB, PASADENA, CA 91125 USA. CALTECH, PASADENA, CA 91125 USA. RP BACHILLER, R (reprint author), CTR ASTRON YEBES, APARTADO 148, E-19080 GUADALAJARA, SPAIN. RI Martin-Pintado, Jesus/H-6107-2015 OI Martin-Pintado, Jesus/0000-0003-4561-3508 NR 58 TC 31 Z9 31 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 DEC 10 PY 1994 VL 437 IS 1 BP 296 EP 304 DI 10.1086/174996 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PW003 UT WOS:A1994PW00300027 ER PT J AU YUAN, C CASSEN, P AF YUAN, C CASSEN, P TI RESONANTLY DRIVEN NONLINEAR DENSITY WAVES IN PROTOSTELLAR DISKS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; BINARIES, CLOSE; STARS, FORMATION ID BINARIES; TAURUS; STARS; MULTIPLICITY; PROTOPLANETS; DYNAMICS AB Recent observations of binary, pre-main-sequence, solar-type stars provide evidence that such systems may coexist with circumstellar disks. The binary disk systems, besides being of general interest for the study of star formation, potentially provide useful tests of companion-disk interaction theories prominent in current hypotheses of planet formation. In this paper, we apply an asymptotic analysis of the nonlinear, resonant interaction of a stellar companion with a disk to understand the dependence of such interactions on the properties of the system: the binary mass ratio, the physical properties of the disk, and the effective dissipation (treated herein as a viscosity). The method is based on a WKBJ approximation and exploits the conditions that the disk is thin and much less massive than the primary, but does not require that the companion-induced disturbance be small. Both isothermal and adiabatic responses are treated. Only circular orbit resonances are considered in this paper. It is demonstrated that the temperature of the disk as well as the relative mass of the companion affects the degree of nonlinearity, and that nonlinearity promotes high wave compression ratios, long wavelengths, and increased propagation distances. Nevertheless, the total torque exerted between the companion and the disk is well represented by linear theory. The amplitudes of density disturbances are reduced by viscosity and nonisothermality. Because resonant interactions are generally strong and capable of driving rapid evolution, one might expect observations of systems undergoing strong, resonant-driven evolution to be rare. In this connection, it is pointed out that the m = 1 resonance is distinguished by being anomalously weaker than the others and is therefore of observational interest. It is speculated that, in conditions of intrinsically small dissipation, the propagation of resonant-driven density waves is limited by the tendency of their wavelength to diminish with distance; and that the propagation distance (and therefore the region of the disk to which angular momentum is redistributed) is set by the distance at which the wavelength becomes comparable to the disk thickness. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94305. RP YUAN, C (reprint author), CUNY CITY COLL,DEPT PHYS,NEW YORK,NY 10031, USA. NR 27 TC 19 Z9 19 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 DEC 10 PY 1994 VL 437 IS 1 BP 338 EP 350 DI 10.1086/175000 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PW003 UT WOS:A1994PW00300031 ER PT J AU FRAIL, DA KULKARNI, SR HURLEY, KC FISHMAN, GJ KOUVELIOTOU, C MEEGAN, CA SOMMER, M BOER, M NIEL, M CLINE, T AF FRAIL, DA KULKARNI, SR HURLEY, KC FISHMAN, GJ KOUVELIOTOU, C MEEGAN, CA SOMMER, M BOER, M NIEL, M CLINE, T TI A SEARCH FOR THE RADIO COUNTERPART TO THE 1994 MARCH 1 GAMMA-RAY BURST SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS; RADIO CONTINUUM, GENERAL ID RELATIVISTIC FIREBALLS AB We report on the results of a search for the radio counterpart to the bright gamma-ray burst of 1994 March 1. Using the Dominion Radio Astrophysical Observatory Synthesis Telescope sensitive, wide-field radio images at 1.4 GHz and 0.4 GHz were made of a region around GRB 940301. A total of 15 separate radio images were obtained at each frequency, sampling a near-continuous range of post-burst timescales between 3 and 15 days, as well as 26, 47, and 99 days. We place an upper limit of 3.5 mJy on a fading/flaring radio counterpart at 1.4 GHz and 55 mJy at 0.4 GHz. Unlike past efforts our counterpart search maintains high sensitivity over two decades of post-burst time durations. Time-variable radio emission after the initial gamma-ray burst is a prediction of all fireball models, currently the most popular model for gamma-ray bursts. Our observations allow us to put significant constraints on the fireball parameters for cosmological models of gamma-ray bursts. C1 CALTECH,PASADENA,CA 91125. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. CTR ETUD SPATIALE RAYONNEMENTS,F-31029 TOULOUSE,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP FRAIL, DA (reprint author), NATL RADIO ASTRON OBSERV,POB 0,SOCORRO,NM 87801, USA. NR 26 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 1994 VL 437 IS 1 BP L43 EP L46 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PW004 UT WOS:A1994PW00400011 ER PT J AU GAZTANAGA, E FRIEMAN, JA AF GAZTANAGA, E FRIEMAN, JA TI BIAS AND HIGH-ORDER GALAXY CORRELATION-FUNCTIONS IN THE APM GALAXY SURVEY SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, CLUSTERING; LARGE-SCALE STRUCTURE OF UNIVERSE ID LARGE-SCALE STRUCTURE; STATISTICS; UNIVERSE; GRAVITY AB On large scales, the higher order moments of the mass distribution, S-J = ($) over bar xi(J)/($) over bar xi(2)(J-1), e.g., the skewness S-3 and kurtosis S-4, can be predicted using nonlinear perturbation theory. Comparison of these predictions with moments of the observed galaxy distribution probes the bias between galaxies and mass. Applying this method to models with initially Gaussian fluctuations and power spectra P(k) similar to that of galaxies in the Automatic Plate Measuring (APM) survey, we find that the predicted higher order moments S-J(R) are in good agreement with those directly inferred from the APM survey in the absence of bias. We use this result to place limits on the linear and nonlinear bias parameters. Models in which the extra power observed on large scales (with respect to the standard cold dark matter [CDM] model) is produced by scale-dependent bias match the APM higher order amplitudes only if nonlinear bias (rather than nonlinear gravity) generates the observed higher order moments. When normalized to COBE DMR, these models are significantly ruled out by the S-3 observations. The cold plus hot dark matter model normalized to COBE can reproduce the APM higher order correlations if one introduces nonlinear bias terms, while the low-density CDM model with a cosmological constant does not require any bias to fit the large-scale amplitudes. C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP GAZTANAGA, E (reprint author), UNIV OXFORD,DEPT PHYS & ASTRON,NUCL & ASTROPHYS LAB,KEBLE RD,OXFORD OX1 3RH,ENGLAND. NR 24 TC 76 Z9 78 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 DEC 10 PY 1994 VL 437 IS 1 BP L13 EP L16 DI 10.1086/187671 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PW004 UT WOS:A1994PW00400004 ER PT J AU DICKEY, JO MARCUS, SL HIDE, R EUBANKS, TM BOGGS, DH AF DICKEY, JO MARCUS, SL HIDE, R EUBANKS, TM BOGGS, DH TI ANGULAR-MOMENTUM EXCHANGE AMONG THE SOLID EARTH, ATMOSPHERE, AND OCEANS - A CASE-STUDY OF THE 1982-1983 EL-NINO EVENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID QUASI-BIENNIAL OSCILLATION; OF-DAY VARIATION; SOUTHERN OSCILLATION; TIME SCALES; ROTATION; LENGTH; FLUCTUATIONS; CIRCULATION; PACIFIC; BALANCE AB The 1982-1983 El Nino/Southern Oscillation (ENSO) event was accompanied by the largest interannual variation in the Earth's rotation rate on record. In this study we demonstrate that atmospheric forcing was the dominant cause for this rotational anomaly, with atmospheric angular momentum (AAM) integrated from 1000 to 1 mbar (troposphere plus stratosphere) accounting for up to 92% of the interannual variance in the length of day (LOD). Winds between 100 and 1 mbar contributed nearly 20% of the variance explained, indicating that the stratosphere can play a significant role in the Earth's angular momentum budget on interannual time scales. Examination of LOD, AAM, and Southern Oscillation Index (SOI) data for a 15-year span surrounding the 1982-1983 event suggests that the strong rotational response resulted from constructive interference between the low-frequency (similar to 4-6 year) and quasi-biennial (similar to 2-3 year) components of the ENSO phenomenon, as well as the stratospheric Quasi-Biennial Oscillation (QBO). Sources of the remaining LOD discrepancy (similar to 55 and 64 mu s rms residual for the European Centre for Medium-Range Forecasting (EC) and U.S. National Meteorological Center (NMC) analyses) are explored; noise and systematic errors in the AAM data are estimated to contribute 18 and 33 mu s, respectively, leaving a residual (rms) of 40 (52) mu s unaccounted for by the EC (NMC) analysis. Oceanic angular momentum contributions (both moment of inertia changes associated with baroclinic waves and motion terms) are shown to be candidates in closing the interannual axial angular momentum budget. C1 USN OBSERV, WASHINGTON, DC 20392 USA. UNIV OXFORD, DEPT PHYS, CLARENDON LAB, OCEANOG GRP, OXFORD OX1 3PU, ENGLAND. RP DICKEY, JO (reprint author), CALTECH, JET PROP LAB, SPACE GEODET SCI & APPLICAT GRP, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 60 TC 24 Z9 28 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD DEC 10 PY 1994 VL 99 IS B12 BP 23921 EP 23937 DI 10.1029/94JB01249 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PX338 UT WOS:A1994PX33800011 ER PT J AU VANDAM, TM BLEWITT, G HEFLIN, MB AF VANDAM, TM BLEWITT, G HEFLIN, MB TI ATMOSPHERIC-PRESSURE LOADING EFFECTS ON GLOBAL POSITIONING SYSTEM COORDINATE DETERMINATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID SURFACE; EARTH; GPS AB Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations, Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is observed at Fairbanks, Alaska (latitude 65 degrees), with a signal RMS of 5 mm. Out of 19 continuously operating GPS sites (with a mean of 281 daily solutions per site), 18 show a positive correlation between the GPS vertical estimates and the modeled loading displacements, Accounting for loading reduces the variance of the vertical station positions on 12 of the 19 sites investigated. Removing the modeled pressure loading from GPS determinations of baseline length for baselines longer than 6000 km reduces the variance on 73 of the 117 baselines investigated. The slight increase in variance for some of the sites and baselines is consistent with expected statistical fluctuations. The results from most stations are consistent with similar to 65% of the modeled pressure load being found in the GPS vertical position measurements. Removing an annual signal from both the measured heights and the modeled load time series leaves this value unchanged. The source of the remaining discrepancy between the modeled and observed loading signal may be the result of (1) anisotropic effects in the Earth's loading response, (2) errors in GPS estimates of tropospheric delay, (3) errors in the surface pressure data, or (4) annual signals in the time series of loading and station heights. In addition, we find that using site dependent coefficients, determined by fitting local pressure to the modeled radial displacements, reduces the variance of the measured station heights as well as of better than using the global convolution sum. C1 UNIV NEWCASTLE UPON TYNE, DEPT SURVEYING, NEWCASTLE UPON TYNE NE1 7RU, TYNE & WEAR, ENGLAND. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP VANDAM, TM (reprint author), NOAA, GEOSCI LAB,NOS,OES 13,SSMV IV, EAST WEST HIGHWAY, SILVER SPRING, MD 20910 USA. NR 19 TC 93 Z9 95 U1 2 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD DEC 10 PY 1994 VL 99 IS B12 BP 23939 EP 23950 DI 10.1029/94JB02122 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PX338 UT WOS:A1994PX33800012 ER PT J AU RICHARDSON, SL FRANCISCO, JS AF RICHARDSON, SL FRANCISCO, JS TI A COMPUTATIONAL STUDY OF THE REACTION OF C-2 WITH CH4 SO MOLECULAR PHYSICS LA English DT Note ID 193 NM AB Ab initio calculations are used to investigate the energetics of the reaction of C-2(X (1) Sigma(g)(+)) with CH4. The heat of reaction is predicted to be exothermic by 5.4 kcal mol(-1) and the barrier height is 0.2 kcal mol(-1) at the QCISD(T)/6-311++G(2df,2p)//UMP2/6-311G(2df,2p) level of theory. The implications of the results are discussed in terms of their importance to the atmospheric evolution of ethane oceans on Titan. C1 HOWARD UNIV,SCH ENGN,DEPT ELECT ENGN,WASHINGTON,DC 20059. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP RICHARDSON, SL (reprint author), HOWARD UNIV,SCH ENGN,CTR STUDY TERR & EXTRATERR ATMOSPHERES,2300 6TH ST NW,WASHINGTON,DC 20059, USA. NR 13 TC 9 Z9 9 U1 0 U2 1 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0026-8976 J9 MOL PHYS JI Mol. Phys. PD DEC 10 PY 1994 VL 83 IS 5 BP 1041 EP 1044 DI 10.1080/00268979400101751 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PY761 UT WOS:A1994PY76100012 ER PT J AU RICCA, A BAUSCHLICHER, CW AF RICCA, A BAUSCHLICHER, CW TI SUCCESSIVE BINDING-ENERGIES OF FE(CO)(5)(+) SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; ELECTRON CORRELATION; WAVE-FUNCTIONS; BOND-ENERGIES; ATOMS; EXCHANGE; FE(CO)5; 1ST-ROW; IONS AB The Fe(CO)(n)(+) geometries are optimized using second-order Moller-Plesset (MP2) perturbation theory, the modified coupled-pair functional (MCPF) approach, and density functional theory (DMT) The Becke-Lee-Yang-Parr (BLYP) functional yields very poor results, while a semiempirical exchange-correlation functional works very well. Fe(CO)(5)(+) has a doubler ground state, while Fe(CO)(n)(+) for n = 1-3 have quartet ground states. For Fe(CO)(4)(+) the doublet and quartet states are too close in energy to definitively determine the ground state. The calculations show that the small third CO binding energy is not due to a change in spin state from a quarter for Fe(CO)(2)(+) to a doublet for Fe(CO)(3)(+), but instead is due to the loss of sdo hybridization when the third CO is added. The theoretical successive CO binding energies agree best with the revised values of Distefano. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 36 TC 221 Z9 221 U1 1 U2 5 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 DEC 8 PY 1994 VL 98 IS 49 BP 12899 EP 12903 DI 10.1021/j100100a015 PG 5 WC Chemistry, Physical SC Chemistry GA PW303 UT WOS:A1994PW30300015 ER PT J AU BECKER, L BADA, JL WINANS, RE BUNCH, TE AF BECKER, L BADA, JL WINANS, RE BUNCH, TE TI FULLERENES IN ALLENDE METEORITE SO NATURE LA English DT Letter ID CHEMISTRY C1 ARGONNE NATL LAB,DIV CHEM,ARGONNE,IL 60439. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP BECKER, L (reprint author), UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,LA JOLLA,CA 92093, USA. NR 10 TC 46 Z9 47 U1 0 U2 3 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD DEC 8 PY 1994 VL 372 IS 6506 BP 507 EP 507 DI 10.1038/372507a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PW082 UT WOS:A1994PW08200033 PM 7990921 ER PT J AU FRANCISCO, JS AF FRANCISCO, JS TI HEAT OF FORMATION DETERMINATION OF THE GROUND AND EXCITED-STATE OF CYANOMETHYLENE (HCCN) RADICAL SO CHEMICAL PHYSICS LETTERS LA English DT Article ID PHOTOCHEMISTRY; MOLECULE; CARBENE; TITAN; BENT AB Ab initio electronic structure theory has been used to characterize the structure of the ground triplet and lowest singlet excited states of cyanomethylene. The geometries, vibrational frequencies, and heats of formation have been determined using second order Moller-Plesset perturbation, single and double excitation configuration interaction, and quadratic configuration interaction theory. The heat of formation is predicted with isodesmic reaction and Gaussian-2 theory (G2) for the ground triplet and first excited singlet states of cyanomethylene. For the ground state Delta H-f,0(0), is 114.8 +/- 2 kcal mol(-1); while for the excited single state it is 126.5 +/- 2 kcal mol(-1). C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 23 TC 13 Z9 13 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD DEC 2 PY 1994 VL 230 IS 4-5 BP 372 EP 376 DI 10.1016/0009-2614(94)01168-0 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PV065 UT WOS:A1994PV06500009 ER PT J AU ACCOLA, A PAULES, G FAULKNER, J GIAMPALMO, G KOZAWA, H AF ACCOLA, A PAULES, G FAULKNER, J GIAMPALMO, G KOZAWA, H TI SPACE STATION FREEDOM GROUND SYSTEMS PROGRAM - A SURVEY SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43rd Astronautical Congress CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC AB The Space Station Freedom will be a permanently manned, low-Earth orbit research facility, elements of which are being provided by the United States, Canada, countries of the European Space Agency and Japan. The facility will be assembled in space and operated well into the twenty-first century. The ground infrastructure must be able to support both assembly and long-term operations. The infrastructure will consist of ground facilities, support systems and the associated planning and management procedures. The key facilities identified to support Space Station Freedom Program (SSFP) integrated operations and their SSFP roles will be described in detail in this paper. Requirements for the integrated ground infrastructure are developed and controlled within the SSFP requirements documentation and baselining processes. A Ground Systems Program directive summarizes key operations functions, roles and responsibilities of the various program participants. During 1992, the SSFP is conducting a major program review of the ground infrastructure including the definition of all facility and support system functional capabilities, interfaces and dataflow requirements. Operations functionality and interface verification tests are being identified and operations readiness dates are being established. RP ACCOLA, A (reprint author), NASA,SPACE STN FREEDOM PROGRAM,CODE MSU-3,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD DEC PY 1994 VL 32 IS 12 BP 797 EP 808 DI 10.1016/0094-5765(94)90086-8 PG 12 WC Engineering, Aerospace SC Engineering GA QE685 UT WOS:A1994QE68500003 ER PT J AU LANDIS, GA AF LANDIS, GA TI MAGNETOBRAKING FOR MARS RETURN VEHICLES SO ACTA ASTRONAUTICA LA English DT Article AB It is proposed that magnetobraking may be used to dissipate hyperbolic excess velocity from a spacecraft returning from Mars to Earth orbit. In magnetobraking, an electrodynamic tether is deployed from the spacecraft. The Earth's magnetic field produces a force on electrical current in the tether, which can be used to either brake or accelerate the spacecraft without expenditure of reaction mass. The peak acceleration on the Mars return is 0.007 m/s(2), and the amount of braking possible is dependent on the density and current-carrying capacity of the tether, but is independent of length. Since energy is produced as the spacecraft velocity decreases, no on-board power source is required. As the spacecraft approaches the Earth, the magnetic field increases and the power produced by the tether increases, reaching a maximum of about 800 W per kg of spacecraft mass at closest approach. RP LANDIS, GA (reprint author), NASA,LEWIS RES CTR 302-1,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD DEC PY 1994 VL 32 IS 12 BP 829 EP 833 DI 10.1016/0094-5765(94)90089-2 PG 5 WC Engineering, Aerospace SC Engineering GA QE685 UT WOS:A1994QE68500006 ER PT J AU SINGH, J JERMAN, J POORMAN, R BHAT, BN AF SINGH, J JERMAN, J POORMAN, R BHAT, BN TI HIGH-ENERGY BEAMS ENHANCE LIFE OF NASA SPACE-SHUTTLE COMBUSTION LINER SO ADVANCED MATERIALS & PROCESSES LA English DT Article C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP SINGH, J (reprint author), PENN STATE UNIV,APPL RES LAB,UNIVERSITY PK,PA 16804, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 0026-0665 J9 ADV MATER PROCESS JI Adv. Mater. Process. PD DEC PY 1994 VL 146 IS 6 BP 60 EP 61 PG 2 WC Materials Science, Multidisciplinary SC Materials Science GA QU066 UT WOS:A1994QU06600010 ER PT J AU SEINER, JM BHAT, TRS PONTON, MK AF SEINER, JM BHAT, TRS PONTON, MK TI MACH WAVE EMISSION FROM A HIGH-TEMPERATURE SUPERSONIC JET SO AIAA JOURNAL LA English DT Article ID HIGH-SPEED JETS; INSTABILITY WAVES AB The paper considers the compressible Rayleigh equation as a model for the Mach wave emission mechanism associated with high-temperature supersonic jets. Solutions to the compressible Rayleigh equation reveal the existence of several families of supersonically convecting instability waves. These waves directly radiate noise to the jet far field. The predicted noise characteristics are compared to previously acquired experimental data for an axisymmetric Mach 2 fully pressure balanced jet (i.e., P(e)/P(a) = 1.0) operating over a range of jet total temperatures from ambient to 1370 K. The results of this comparison show that the first-order supersonic instability wave and the Kelvin-Helmholtz first-, second-, and third-order modes have directional radiation characteristics that are in agreement with observed data. The assumption of equal initial amplitudes for all of the waves leads to the conclusion that the flapping mode of instability dominates the noise radiation process of supersonic jets. At a jet temperature of 1370 K, supersonic instability waves are predicted to dominate the noise radiated at high frequency at narrow angles to the jet axis. C1 OLD DOMINION UNIV,DEPT MECH ENGN,NORFOLK,VA 23529. RP SEINER, JM (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH & ACOUST,HAMPTON,VA 23681, USA. NR 14 TC 16 Z9 16 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 DEC PY 1994 VL 32 IS 12 BP 2345 EP 2350 DI 10.2514/3.12298 PG 6 WC Engineering, Aerospace SC Engineering GA QB301 UT WOS:A1994QB30100002 ER PT J AU SREE, D KJELGARD, SO SELLERS, WL AF SREE, D KJELGARD, SO SELLERS, WL TI EFFECT OF NON-POISSON SAMPLES ON TURBULENCE SPECTRA FROM LASER VELOCIMETRY SO AIAA JOURNAL LA English DT Note C1 NASA,LANGLEY RES CTR,EXPTL METHORDS BRANCH,HAMPTOM,VA 23681. RP SREE, D (reprint author), TUSKEGEE UNIV,DEPT MECH ENGN,TUSKEGEE,AL 36088, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD DEC PY 1994 VL 32 IS 12 BP 2480 EP 2481 DI 10.2514/3.12320 PG 2 WC Engineering, Aerospace SC Engineering GA QB301 UT WOS:A1994QB30100024 ER PT J AU BIKLE, DD HARRIS, J HALLORAN, BP MOREYHOLTON, E AF BIKLE, DD HARRIS, J HALLORAN, BP MOREYHOLTON, E TI ALTERED SKELETAL PATTERN OF GENE-EXPRESSION IN RESPONSE TO SPACEFLIGHT AND HINDLIMB ELEVATION SO AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM LA English DT Article DE BONE; ALKALINE PHOSPHATASE; OSTEOCALCIN; INSULIN-LIKE GROWTH FACTOR; MATURATION ID GROWTH FACTOR-I; SIMULATED WEIGHTLESSNESS; BONE MATURATION; WEIGHT-BEARING; RATS; SUSPENSION; MUSCLE AB Spaceflight leads to osteopenia, in part by inhibiting bone formation. Using an animal model (hindlimb elevation) that simulates the weightlessness of spaceflight, we and others showed a reversible inhibition of bone formation and bone mineralization. In this study, we have measured the mRNA levels of insulin-like growth factor I (IGF-I), IGF-I receptor (IGF-IR), alkaline phosphatase, and osteocalcin in the tibiae of rats flown aboard National Aeronautics and Space Administration Shuttle Flight STS-54 and compared the results with those obtained from their ground-based controls and from the bones of hindlimb-elevated animals. Spaceflight and hindlimb elevation transiently increase the mRNA levels for IGF-I, IGF-IR, and alkaline phosphatase but decrease the mRNA levels for osteocalcin. The changes in osteocalcin and alkaline phosphatase mRNA levels are consistent with a shift toward decreased maturation, whereas the rise in IGF-I and IGF-IR mRNA levels may indicate a compensatory response to the fall in bone formation. mie conclude that skeletal unloading during spaceflight or hindlimb elevation resets the pattern of gene expression in the osteoblast, giving it a less mature profile. C1 UNIV CALIF SAN FRANCISCO, DEPT MED, SAN FRANCISCO, CA 94121 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP BIKLE, DD (reprint author), VET ADM MED CTR, 4150 CLEMENT ST, SAN FRANCISCO, CA 94121 USA. NR 33 TC 67 Z9 70 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0193-1849 J9 AM J PHYSIOL-ENDOC M JI Am. J. Physiol.-Endocrinol. Metab. PD DEC PY 1994 VL 267 IS 6 BP E822 EP E827 PG 6 WC Endocrinology & Metabolism; Physiology SC Endocrinology & Metabolism; Physiology GA PX940 UT WOS:A1994PX94000004 PM 7810622 ER PT J AU FISCHER, U AF FISCHER, U TI LEARNING WORDS FROM CONTEXT AND DICTIONARIES - AN EXPERIMENTAL COMPARISON SO APPLIED PSYCHOLINGUISTICS LA English DT Article ID VOCABULARY INSTRUCTION; COMPREHENSION; ACQUISITION; MEANINGS; MODEL AB This research investigates the independent and interactive effects of contextual and definitional information on vocabulary learning. German students of English received either a text with unfamiliar English words or their monolingual English dictionary entries. A third group of subjects were given both text and dictionary entries. Subjects used each target word in an English sentence and then translated their sentences into German. The translations showed whether students had understood the meaning of a target word and permitted the specification of comprehension strategies. Subjects who had received text and dictionary entries tended to favor the dictionary and thus performed no better than students in the other experimental groups. Subjects learning words from context replaced unfamiliar words with familiar words conforming to contextual constraints. Subjects in the dictionary group commonly substituted a relevant part of the definition for the headword. Lexical errors occurred for different reasons: substitutions in the dictionary condition were unconstrained by context; substitutions in the text condition were not sufficiently constrained by context. The study shows that information about the contexts in which words are used is crucial for acquiring an adequate understanding of word meanings.1 C1 PRINCETON UNIV,PRINCETON,NJ 08544. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 45 TC 16 Z9 16 U1 0 U2 3 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0142-7164 J9 APPL PSYCHOLINGUIST JI Appl. Psycholinguist. PD DEC PY 1994 VL 15 IS 4 BP 551 EP 574 DI 10.1017/S0142716400006901 PG 24 WC Linguistics; Psychology, Experimental SC Linguistics; Psychology GA QB511 UT WOS:A1994QB51100005 ER PT J AU DRAKE, SA LINSKY, JL BOOKBINDER, JA AF DRAKE, SA LINSKY, JL BOOKBINDER, JA TI A SEARCH FOR RADIO-EMISSION FROM THE NONMAGNETIC CHEMICALLY PECULIAR STARS SO ASTRONOMICAL JOURNAL LA English DT Article ID UPPER-MAIN-SEQUENCE; X-RAY-EMISSION; MAGNETIC-FIELDS; AM STARS; AP; BINARIES C1 NATL INST STAND & TECHNOL,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. UNIV COLORADO,BOULDER,CO 80309. SAO,CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP DRAKE, SA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 668,GREENBELT,MD 20771, USA. NR 28 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD DEC PY 1994 VL 108 IS 6 BP 2203 EP 2206 DI 10.1086/117231 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PU983 UT WOS:A1994PU98300021 ER PT J AU WELLS, LA PHILLIPS, MM SUNTZEFF, NB HEATHCOTE, SR HAMUY, M NAVARRETE, M FERNANDEZ, M WELLER, WG SCHOMMER, RA KIRSHNER, RP LEIBUNDGUT, B WILLNER, SP PELETIER, RF SCHLEGEL, EM WHEELER, JC HARKNESS, RP BELL, DJ MATTHEWS, JM FILIPPENKO, AV SHIELDS, JC RICHMOND, MW JEWITT, D LUU, J TRAN, HD APPLETON, PN ROBSON, EI TYSON, JA GUHATHAKURTA, P EDER, JA BOND, HE POTTER, M VEILLEUX, S PORTER, AC HUMPHREYS, RM JANES, KA WILLIAMS, TB COSTA, E RUIZ, MT LEE, JT LUTZ, JH RICH, RM WINKLER, PF TYSON, ND AF WELLS, LA PHILLIPS, MM SUNTZEFF, NB HEATHCOTE, SR HAMUY, M NAVARRETE, M FERNANDEZ, M WELLER, WG SCHOMMER, RA KIRSHNER, RP LEIBUNDGUT, B WILLNER, SP PELETIER, RF SCHLEGEL, EM WHEELER, JC HARKNESS, RP BELL, DJ MATTHEWS, JM FILIPPENKO, AV SHIELDS, JC RICHMOND, MW JEWITT, D LUU, J TRAN, HD APPLETON, PN ROBSON, EI TYSON, JA GUHATHAKURTA, P EDER, JA BOND, HE POTTER, M VEILLEUX, S PORTER, AC HUMPHREYS, RM JANES, KA WILLIAMS, TB COSTA, E RUIZ, MT LEE, JT LUTZ, JH RICH, RM WINKLER, PF TYSON, ND TI THE TYPE-IA SUPERNOVA 1989B IN NGC-3627 (M66) SO ASTRONOMICAL JOURNAL LA English DT Article ID LIGHT CURVES; STANDARD STARS; SPECTROPHOTOMETRIC STANDARDS; CCD PHOTOMETRY; SPECTRA; NGC-3627; NOVAE; SN-1991T C1 HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RGO,E-38700 SANTA CRUZ PALMA,SPAIN. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV ILLINOIS,DEPT ASTRON,URBANA,IL 60801. UNIV BRITISH COLUMBIA,DEPT GEOPHYS & ASTRON,VANCOUVER V6T 1Z4,BC,CANADA. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. STANFORD UNIV,DEPT PHYS,STANFORD,CA 94305. CALTECH,PASADENA,CA 91125. IOWA STATE UNIV SCI & TECHNOL,DEPT PHYS,ASTRON PROGRAM,AMES,IA 50011. LANCASHIRE POLYTECH,SCH PHYS & ASTRON,PRESTON PR1 2TQ,LANCS,ENGLAND. AT&T BELL LABS,MURRAY HILL,NJ 07974. PRINCETON UNIV OBSERV,PRINCETON,NJ 08540. NATL ASTRON & IONOSPHERE CTR,ARECIBO OBSERV,ARECIBO,PR 00613. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. KITT PEAK NATL OBSERV,NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. UNIV MINNESOTA,DEPT ASTRON,MINNEAPOLIS,MN 55455. BOSTON UNIV,DEPT ASTRON,BOSTON,MA 02215. RUTGERS STATE UNIV,DEPT PHYS & ASTRON,SERIN PHYS LAB,PISCATAWAY,NJ 08854. UNIV CHILE,DEPT ASTRON,SANTIAGO,CHILE. YALE UNIV,DEPT ASTRON,NEW HAVEN,CT 06511. WASHINGTON STATE UNIV,ASTRON PROGRAM,PULLMAN,WA 99164. COLUMBIA UNIV,DEPT ASTRON,NEW YORK,NY 10027. MIDDLEBURY COLL,DEPT PHYS,MIDDLEBURY,VT 05753. PRINCETON UNIV,DEPT ASTROPHYS SCI,PRINCETON,NJ 08540. RP WELLS, LA (reprint author), NATL OPT ASTRON OBSERV,CERRO TOLOLO INTER AMER OBSERV,CASILLA 603,LA SERENA,CHILE. RI Peletier, Reynier/B-9633-2012; Costa, Edgardo /I-5274-2016; Ruiz, Maria Teresa/I-5770-2016; Hamuy, Mario/G-7541-2016; OI Costa, Edgardo /0000-0003-4142-1082; Ruiz, Maria Teresa/0000-0002-6799-1537; Appleton, Philip/0000-0002-7607-8766 NR 59 TC 129 Z9 129 U1 0 U2 9 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 DEC PY 1994 VL 108 IS 6 BP 2233 EP 2250 DI 10.1086/117236 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PU983 UT WOS:A1994PU98300026 ER PT J AU CAMPINS, H TELESCO, CM OSIP, DJ RIEKE, GH RIEKE, MJ SCHULZ, B AF CAMPINS, H TELESCO, CM OSIP, DJ RIEKE, GH RIEKE, MJ SCHULZ, B TI THE COLOR TEMPERATURE OF (2060)CHIRON - A WARM AND SMALL NUCLEUS SO ASTRONOMICAL JOURNAL LA English DT Article ID 2060-CHIRON; PHOTOMETRY; 1992-AD; COMETS; COMA; CCD C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. ESA,ESTEC,NOORDWIJK,NETHERLANDS. RP CAMPINS, H (reprint author), UNIV FLORIDA,SSRB 211,GAINESVILLE,FL 32611, USA. NR 37 TC 54 Z9 54 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 DEC PY 1994 VL 108 IS 6 BP 2318 EP 2322 DI 10.1086/117244 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PU983 UT WOS:A1994PU98300034 ER PT J AU NORTH, P BERTHET, S LANZ, T AF NORTH, P BERTHET, S LANZ, T TI THE NATURE OF THE F STR LAMBDA-4077 STARS .3. SPECTROSCOPY OF THE BARIUM DWARFS AND OTHER CP STARS (VOL 281, PG 775, 1994) SO ASTRONOMY & ASTROPHYSICS LA English DT Correction C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP NORTH, P (reprint author), UNIV LAUSANNE, INST ASTRON, CH-1290 CHAVANNES DES BOIS, SWITZERLAND. NR 1 TC 1 Z9 1 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD DEC PY 1994 VL 292 IS 1 BP 350 EP 350 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV400 UT WOS:A1994PV40000038 ER PT J AU PANAGI, PM ODELL, MA COLLIER CAMERON, A ROBINSON, RD AF PANAGI, PM ODELL, MA COLLIER CAMERON, A ROBINSON, RD TI SPECTROSCOPY OF THE YOUNG CLUSTER BLANCO-1 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE GALAXY, OPEN CLUSTERS AND ASSOCIATIONS; INDIVIDUAL, BLANCO 1; STARS, ABUNDANCES; STARS, CHROMOSPHERES; STARS, DISTANCES ID MAIN-SEQUENCE STARS; MODEL CHROMOSPHERES; PROFILES; LITHIUM; ALPHA; LINES; DWARF AB We present spectroscopic observations of some 115 stars of the cluster Blanco 1, extending from the Ca II(H,K) region to the Ca II(I-R) triplet, supporting an age similar to that of the young cluster alpha Persei. The H alpha absorption equivalent width vs (B - V) diagram forms a well-defined locus, with decreasing absorption equivalent width for decreasing effective temperature, akin to solar neighbourhood dwarfs. A large spread in the Ca II surface flux, as a function of (B - V), also indicates the presence of a high degree of surface inhomogeneity, synonymous with high magnetic activity in young stars. A drop-off in the Ca II flux at (B - V) = 1.0 is also similar to the solar neighbourhood stars, and shows that the primary chromospheric cooling changes from the Ca II and Mg II lines to the Balmer lines. The mean chromospheric temperature for stars at 4800 K lies between 8000 K and 10000 K, based on theoretical models, which is somewhat higher than the older solar neighbourhood dwarfs. The high mean Ca II surface flux of the sample is also consistent with that of other young clusters. We were able to measure the equivalent width of the Li(6708) line, whose strength as a function of(B - V) indicates an age similar to the young cluster a Persei. The lithium abundance decreases with decreasing effective temperature, consistent with the premise of lithium depletion in stars with larger convection zones. Using published photometry and a recent ZAMS fitting method, we also re-define the distance to the cluster to be 246 pc. C1 GODDARD SPACE FLIGHT CTR, COMP SCI CORP, ASTRON PROGRAM, GREENBELT, MD 20771 USA. RP PANAGI, PM (reprint author), UNIV SUSSEX, CTR ASTRON, BRIGHTON BN1 9QH, E SUSSEX, ENGLAND. NR 36 TC 9 Z9 9 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 DEC PY 1994 VL 292 IS 2 BP 439 EP 449 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PW489 UT WOS:A1994PW48900013 ER PT J AU BENNETT, CL KOGUT, A HINSHAW, G BANDAY, AJ WRIGHT, EL GORSKI, KM WILKINSON, DT WEISS, R SMOOT, GF MEYER, SS MATHER, JC LUBIN, P LOEWENSTEIN, K LINEWEAVER, C KEEGSTRA, P KAITA, E JACKSON, PD CHENG, ES AF BENNETT, CL KOGUT, A HINSHAW, G BANDAY, AJ WRIGHT, EL GORSKI, KM WILKINSON, DT WEISS, R SMOOT, GF MEYER, SS MATHER, JC LUBIN, P LOEWENSTEIN, K LINEWEAVER, C KEEGSTRA, P KAITA, E JACKSON, PD CHENG, ES TI COSMIC TEMPERATURE-FLUCTUATIONS FROM 2 YEARS OF COBE DIFFERENTIAL MICROWAVE RADIOMETERS OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS; LARGE-SCALE STRUCTURE OF UNIVERSE ID COLD DARK-MATTER; LARGE-SCALE STRUCTURE; ANGULAR-CORRELATION FUNCTION; COSMOLOGICAL SCENARIO; EXTRAGALACTIC OBJECTS; STATISTICAL-ANALYSIS; UNIVERSE; ANISOTROPY; MAPS; HOT AB The first two years of COBE Differential Microwave Radiometers (DMR) observations of the cosmic microwave background (CMB) anisotropy are analyzed and compared with our previously published first year results. The results are consistent, but the addition of the second year of data increases the precision and accuracy of the detected CMB temperature fluctuations. The 2 yr 53 GHz data are characterized by rms temperature fluctuations of (Delta T)(rms)(7 degrees) = 44 +/- 7 mu K and (Delta T)(rms)(10 degrees) = 30.5 +/- 2.7 mu K at 7 degrees and 10 degrees angular resolution, respectively. The 53 x 90 GHz cross-correlation amplitude at zero lag is C(0)(1/2) = 36 +/- 5 mu K (68% CL) for the unsmoothed (7 degrees resolution) DMR data. We perform a likelihood analysis of the cross-correlation function, with Monte Carlo simulations to infer biases of the method, for a power-law model of initial density fluctuations, P(k) proportional to k(n). The Monte Carlo simulations indicate that derived estimates of n are biased by +0.11 +/- 0.0l, while the subset of simulations with a low quadrupole (as observed) indicate a bias of +0.31 +/- 0.04. Derived values for 68% confidence intervals are given corrected (and not corrected) for our estimated biases. Including the quadrupole anisotropy, the most likely quadrupole-normalized amplitude is Q(rms-PS) = 14.3(-3.3)(+5.2) mu K (12.8(-3.3)(+5.2) mu K) with a spectral index n = 1.42(0.55)(+0.49) (n = 1.53(-0.55)(+0.49)). With n fixed to 1.0 the most likely amplitude is 18.2 +/- 1.5 mu K (17.4 +/- 1.5 mu K). The marginal likelihood of n is 1.42 +/- 0.37 (1.53 +/- 0.37). Excluding the quadrupole anisotropy, the most likely quadrupole-normalized amplitude is Q(rms-PS) = 17.4(-5.2)(+7.5) mu K (15.8(-5.2)(+7.5) mu K) with a spectral index n = 1.11(-0.55)(+0.60) (n = 1.22(-0.55)(+0.60)) With n fixed to 1.0 the most likely amplitude is 18.6 +/- 1.6 mu K (18.2 +/- 1.6 mu K). The marginal likelihood of n is 1.11 +/- 0.40 (1.22 +/- 0.40). Our best estimate of the dipole from the 2 yr DMR data is 3.363 +/- 0.024 mK toward Galactic coordinates (l, b) = (264 degrees.4 +/- 0 degrees.2, +48 degrees.1 +/- 0 degrees.4), and our best estimate of the rms quadrupole amplitude in our sky is 6 +/- 3 mu K (68% CL). C1 NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. UNIV CALIF LOS ANGELES, DEPT ASTRON, LOS ANGELES, CA 90024 USA. PRINCETON UNIV, DEPT PHYS, PRINCETON, NJ 08540 USA. MIT, DEPT PHYS, CAMBRIDGE, MA 02139 USA. UNIV CALIF BERKELEY, LAWRENCE BERKELEY LAB, BERKELEY, CA 94720 USA. UNIV CHICAGO, ENRICO FERMI INST, DEPT ASTRON & ASTROPHYS, CHICAGO, IL 60637 USA. UNIV CALIF SANTA BARBARA, DEPT PHYS, SANTA BARBARA, CA 93106 USA. RP BENNETT, CL (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 685, GREENBELT, MD 20771 USA. RI Kogut, Alan/D-6293-2012 NR 77 TC 244 Z9 246 U1 0 U2 7 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 1994 VL 436 IS 2 BP 423 EP 442 DI 10.1086/174918 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV552 UT WOS:A1994PV55200001 ER PT J AU WRIGHT, EL SMOOT, GF BENNETT, CL LUBIN, PM AF WRIGHT, EL SMOOT, GF BENNETT, CL LUBIN, PM TI ANGULAR POWER SPECTRUM OF THE MICROWAVE BACKGROUND ANISOTROPY SEEN BY THE COBE DIFFERENTIAL MICROWAVE RADIOMETER SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS; LARGE-SCALE STRUCTURE OF UNIVERSE ID INFLATIONARY UNIVERSE; EXTRAGALACTIC OBJECTS; STATISTICAL-ANALYSIS; SCALE ANISOTROPY; RADIATION; FLUCTUATIONS; CATALOGS; SEARCH; MAPS AB The angular power spectrum estimator developed by Peebles (1973) and Hauser and Peebles (1973) has been modified and applied to the 2 yr maps produced by the COBE DMR. The power spectrum of the real sky has been compared to the power spectra of a large number of simulated random skies produced with noise equal to the observed noise and primordial density fluctuation power spectra of power-law form, with P(k) proportional to k(n). Within the limited range of spatial scales covered by the COBE DMR, corresponding to spherical harmonic indices 3 less than or equal to l less than or similar to 30, the best-fitting value of the spectral index is n = 1.25(-0.45)(+0.4) with the Harrison-Zel'dovich value n = 1 approximately 0.5 sigma below the best fit. For 3 less than or equal to l less than or similar to 19, the best fit is n = 1.46(-0.44)(+0.39). Comparing the COBE DMR Delta T/T at small l to the Delta T/T at 1 approximate to 50 from degree scale anisotropy experiments gives a smaller range of acceptable spectral indices which includes n = 1. C1 UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF SANTA BARBARA,DEPT PHYS,SANTA BARBARA,CA 93106. RP WRIGHT, EL (reprint author), UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024, USA. NR 44 TC 66 Z9 66 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 DEC 1 PY 1994 VL 436 IS 2 BP 443 EP 451 DI 10.1086/174919 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV552 UT WOS:A1994PV55200002 ER PT J AU LINEWEAVER, CH SMOOT, GF BENNETT, CL WRIGHT, EL TENORIO, L KOGUT, A KEEGSTRA, PB HINSHAW, G BANDAY, AJ AF LINEWEAVER, CH SMOOT, GF BENNETT, CL WRIGHT, EL TENORIO, L KOGUT, A KEEGSTRA, PB HINSHAW, G BANDAY, AJ TI CORRELATED NOISE IN THE COBE DMR SKY MAPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS; METHODS, STATISTICAL ID DIFFERENTIAL MICROWAVE RADIOMETERS AB The COBE DMR sky maps contain low-level correlated noise. We obtain estimates of the amplitude and pattern of the correlated noise from three techniques: angular averages of the covariance matrix, Monte Carlo simulations of two-point correlation functions, and direct analysis of the DMR maps. The results from the three methods are mutually consistent. The noise covariance matrix of a DMR sky map is diagonal to an accuracy of better than 1%. For a given sky pixel, the dominant noise covariance occurs with the ring of pixels at an angular separation of 60 degrees due to the 60 degrees separation of the DMR horns. The mean covariance at 60 degrees is 0.45%(+0.18)(-0.14) of the mean variance. Additionally, the variance in a given pixel is 0.7% greater than would be expected from a single beam experiment with the same noise properties. Autocorrelation functions suffer from a similar to 1.5 sigma positive bias at 60 degrees while cross-correlations have no bias. Published COBE DMR results are not significantly affected by correlated noise. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV CALIF LOS ANGELES, DEPT ASTRON, LOS ANGELES, CA 90024 USA. NASA, GODDARD SPACE FLIGHT CTR, HUGHES STX CORP, GREENBELT, MD 20771 USA. NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. RP LINEWEAVER, CH (reprint author), UNIV CALIF BERKELEY, CTR PARTICLE ASTROPHYS, LAWRENCE BERKELEY LAB, SPACE SCI LAB, BLDG 50-205, BERKELEY, CA 94720 USA. RI Kogut, Alan/D-6293-2012 NR 15 TC 41 Z9 41 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 1994 VL 436 IS 2 BP 452 EP 455 DI 10.1086/174920 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV552 UT WOS:A1994PV55200003 ER PT J AU DWEK, E SLAVIN, J AF DWEK, E SLAVIN, J TI ON THE DETERMINATION OF THE COSMIC INFRARED BACKGROUND-RADIATION FROM THE HIGH-ENERGY SPECTRUM OF EXTRAGALACTIC GAMMA-RAY SOURCES SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL LACERTAE OBJECTS, INDIVIDUAL (MARKARIAN 421); DIFFUSE RADIATION; DUST, EXTINCTION; GALAXY, STRUCTURE; GAMMA RAYS, OBSERVATIONS ID EGRET TELESCOPE; MARKARIAN-421; 3C-279; DUST AB In a recent paper Stecker, De Jager, and Salamon have suggested using the observed similar to MeV to TeV spectra of extragalactic gamma-ray sources as probes of the local density of the cosmic infrared background radiation (CIBR) and have subsequently claimed a first possible measurement of the CIBR from the analysis of the gamma-ray spectrum of Mrk 421 (De Jager, Stecker, and Salamon). The CIBR from normal galaxies consists of two components: a stellar emission component (CIBRs), and a thermal dust emission component (CIBRd). Photons with energies in the similar to 0.1-2 TeV range interact primarily with the CIBRs, whereas interactions with CIBRd dominate the absorption of photons in the similar to 2-100 TeV energy range. SDS92 and DSS94 considered only the interaction of the gamma-rays with the dust emission component of the CIBR. We present here an improved analysis of the absorption of extragalactic TeV gamma rays by the CIBR, taking the dual nature of its origin into account. Applying the analysis to the observed gamma-ray spectrum of Mrk 421, a BL Lac object at z = 0.031, we find in agreement with DSS94 tentative evidence for absorption by the CIBRd. However, we find no evidence for absorption by the CIBRs. Our analysis therefore limits the detection of the CIBR to the similar to 15-40 mu m wavelength regime which, considering the uncertainties in the highest energy (>4 TeV) data and in the possibility of absorption inside the source, many turn out to be an upper limit on its energy density. At shorter wavelengths (lambda approximate to 1-15 mu m), where the gamma-ray interactions are dominated by the CIBRs, our analysis definitely yields only an upper limit on the energy density of the CIBR. In contrast, DSS94 have claimed a possible first measurement of the CIBR over the entire 1-120 mu m wavelength region. The upper limit on the CIBRs and tentative detection of the CIBRd are consistent with normal galaxies contributing most of the energy to the CIBR, and constrain the contribution of some exotic sources. With careful modeling of infrared foreground emissions, these constraints on the CIBR are above the values measurable by the DIRBE experiment on board the COBE satellite. RP DWEK, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. OI Slavin, Jonathan/0000-0002-7597-6935 NR 24 TC 58 Z9 58 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 1994 VL 436 IS 2 BP 696 EP 704 DI 10.1086/174943 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV552 UT WOS:A1994PV55200026 ER PT J AU GOLDEN, RL GRIMANI, C KIMBELL, BL STEPHENS, SA STOCHAJ, SJ WEBBER, WR BASINI, G BONGIORNO, F BRANCACCIO, FM RICCI, M ORMES, JF STREITMATTER, RE PAPINI, P SPILLANTINI, P BRUNETTI, MT CODINO, A MENICHELLI, M SALVATORI, I DEPASCALE, MP MORSELLI, A PICOZZA, P AF GOLDEN, RL GRIMANI, C KIMBELL, BL STEPHENS, SA STOCHAJ, SJ WEBBER, WR BASINI, G BONGIORNO, F BRANCACCIO, FM RICCI, M ORMES, JF STREITMATTER, RE PAPINI, P SPILLANTINI, P BRUNETTI, MT CODINO, A MENICHELLI, M SALVATORI, I DEPASCALE, MP MORSELLI, A PICOZZA, P TI OBSERVATIONS OF COSMIC-RAY ELECTRONS AND POSITRONS USING AN IMAGING CALORIMETER SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS; ELEMENTARY PARTICLES; INSTRUMENTATION, SPECTROGRAPHS AB A balloon-borne magnet spectrometer system was flown for 5.5 hr at an altitude of more than 117,000 feet from Prince Albert, Saskatchewan (Canada), on 1989 September 5, when the Newark neutron monitor rate was 2952. The instrument was a modified version of the one used to observe antiprotons in 1979. The most significant modification was the addition of an imaging calorimeter, 7.33 radiation lengths thick. Inclusion of the calorimeter has significantly improved the ability to distinguish electrons and positrons from the other constituents of the cosmic rays. The absolute electron flux has been determined in the energy interval 1.3-26 GeV. The electron spectrum at the top of the atmosphere was found to be J(e-) = 177E(-(3.15+/-0.13)) electrons/ (m(-2) sr s GeV) in the energy range 4.0-26 GeV. Below 4 GeV, the spectrum showed flattening, which is consistent with the effect of solar modulation. The e(+)/(e(+) + e(-)) ratio was found to be (0.11 +/- 0.03) in the energy range 5.2-13 GeV. C1 IST NAZL FIS NUCL,NAZL FRASCATI LAB,I-00044 FRASCATI,ITALY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV FLORENCE,DIPARTIMENTO FIS,I-50125 FLORENCE,ITALY. IST NAZL FIS NUCL,I-50125 FLORENCE,ITALY. UNIV PERUGIA,DIPARTIMENTO FIS,I-06100 PERUGIA,ITALY. IST NAZL FIS NUCL,I-06100 PERUGIA,ITALY. UNIV ROME,DIPARTIMENTO FIS,I-00133 ROME,ITALY. IST NAZL FIS NUCL,SEZ ROMA,I-00133 ROME,ITALY. TATA INST FUNDAMENTAL RES,BOMBAY,MAHARASHTRA,INDIA. UNIV ROMA LA SAPIENZA,DIPARTIMENTO METODI & MODELLI MATEMAT,ROME,ITALY. RP GOLDEN, RL (reprint author), NEW MEXICO STATE UNIV,BOX 3-PAL,LAS CRUCES,NM 88003, USA. RI Morselli, Aldo/G-6769-2011; OI Morselli, Aldo/0000-0002-7704-9553; Picozza, Piergiorgio/0000-0002-7986-3321; Papini, Paolo/0000-0003-4718-2895 NR 16 TC 110 Z9 111 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 DEC 1 PY 1994 VL 436 IS 2 BP 769 EP 775 DI 10.1086/174951 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV552 UT WOS:A1994PV55200034 ER PT J AU MORIARTYSCHIEVEN, GH WANNIER, PG KEENE, J TAMURA, M AF MORIARTYSCHIEVEN, GH WANNIER, PG KEENE, J TAMURA, M TI CIRCUMPROTOSTELLAR ENVIRONMENTS .2. ENVELOPES, ACTIVITY, AND EVOLUTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; INFRARED, STARS; STARS, FORMATION; STARS, PRE-MAIN-SEQUENCE ID YOUNG STELLAR OBJECTS; CIRCUMSTELLAR DISKS; T-TAURI; MOLECULAR OUTFLOWS; CLOUD; L1551NE; MASSES; GRAINS; CORES; STARS AB We have obtained 800 and 1100 mu m photometric observations of a complete, flux-limited, IRAS-selected sample of cold sources in Taurus, whose infrared and molecular properties indicate them to be low-mass protostars which are younger than T Tauri stars. The goal of this study is to understand the role of the circumstellar envelope and disk during low-mass star formation and to search for signs of evolution. We find a good correlation between the submillimeter flux density (as well as of envelope mass) with both the mechanical luminosity of the molecular outflow and with the far-infrared luminosity, presumably produced by accretion onto the protostar. This suggests that the mass of the disk/envelope may be linked to the rate of accretion onto the protostar and to the generation of outflows. However, in contrast to the results of Cabrit & Andre (1991) we see no evidence for a lower limit to the disk/envelope mass which can produce outflows. We also find a significant difference between the spectral energy distributions at submillimeter wavelengths of embedded protostars compared to optically visible T Tauri stars. The more evolved (T Tauri) objects tend to have shallower spectral indices than embedded sources, suggesting (1) an evolution of dust grains, and/or (2) a more compact envelope and optically thick disk in the older objects. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,CALTECH SUBMILLIMETER OBSERV,DIV PHYS MATH & ASTRON,PASADENA,CA 91125. NATL ASTRON OBSERV,MITAKA,TOKYO 181,JAPAN. RP MORIARTYSCHIEVEN, GH (reprint author), NATL RES COUNCIL CANADA,DOMINION RADIO ASTROPHYS OBSERV,BOX 248,PENTICTON V2A 6K3,BC,CANADA. NR 31 TC 54 Z9 54 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 DEC 1 PY 1994 VL 436 IS 2 BP 800 EP 806 DI 10.1086/174956 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV552 UT WOS:A1994PV55200039 ER PT J AU RAMATY, R SCHWARTZ, RA ENOME, S NAKAJIMA, H AF RAMATY, R SCHWARTZ, RA ENOME, S NAKAJIMA, H TI GAMMA-RAY AND MILLIMETER-WAVE EMISSIONS FROM THE 1991 JUNE X-CLASS SOLAR-FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, FLARES; SUN, RADIO RADIATION; SUN, X-RAYS, GAMMA RAYS ID RELATIVISTIC ELECTRON-TRANSPORT; PARTICLES; LINE; ACCELERATION; RADIATION; NOBEYAMA; 17-GHZ; MODEL AB We have studied the spectacular 1991 June X-class hares using gamma-ray data from the Charged Particle Detectors (CPDs) of the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) and 80 GHz millimeter data from Nobeyama, Japan. The CPDs were the only CGRO instrument that did not saturate during the extremely intense 1991 June 4 flare. We have shown that for this flare the CPDs respond to MeV photons, most of which are due to bremsstrahlung produced by relativistic electrons at the Sun. We have further shown that the gamma-ray and millimeter observations agree numerically if the 80 GHz radiation is gyrosynchrotron radiation produced by trapped electrons and the gamma rays are thick-target bremsstrahlung due to electrons precipitating out of the trap. The requirement that the trapping time obtained from the numerical comparison be consistent with the observed time profiles implies a magnetic field between about 200 and 300 G and an electron spectral index between about 3 to 5. By comparing the CPD observations with both the 80 GHz data and nuclear line data from the Energetic Gamma Ray Experiment Telescope (EGRET) and the Oriented Scintillation Spectroscopy Experiment (OSSE) on CGRO for the hares of June 4, 6, 9, and 11, we found that the ratio of the CPD counts to both the millimeter flux densities and the nuclear line fluences decreases with decreasing flare heliocentric angle. All of these flares were produced in the same active region. We interpreted this result in terms of a loop model in which the gyrosynchrotron emission is produced in the coronal portion of the loop where the electrons are kept isotropic by pitch angle scattering due to plasma turbulence, while the bremsstrahlung is produced by precipitating electrons that interact anisotropically. We found that the trapping time in the coronal portion is time dependent, reaching a minimum of about 10 s at the peak of the CPD count rate. We suggested the damping of the turbulence as a possible reason for the variation of the trapping time. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. NOBEYAMA RADIO OBSERV, MINAMISA KU, NAGANO 38413, JAPAN. RP RAMATY, R (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. NR 41 TC 79 Z9 79 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 1994 VL 436 IS 2 BP 941 EP 949 DI 10.1086/174969 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV552 UT WOS:A1994PV55200052 ER PT J AU BANDAY, AJ GORSKI, KM TENORIO, L WRIGHT, EL SMOOT, GF LINEWEAVER, CH KOGUT, A HINSHAW, G BENNETT, CL AF BANDAY, AJ GORSKI, KM TENORIO, L WRIGHT, EL SMOOT, GF LINEWEAVER, CH KOGUT, A HINSHAW, G BENNETT, CL TI ON THE RMS ANISOTROPY AT 7-DEGREES AND 10-DEGREES OBSERVED IN THE COBE(1)-DMR 2-YEAR SKY MAPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS AB The frequency-independent rms temperature fluctuations determined from the COBE-DMR two-year sky maps are used to infer the parameter Q(rms-PS), which characterizes the normalization of power-law models of primordial cosmological temperature anisotropy, for a forced fit to a scale-invariant Harrison-Zel'dovich (n = 1) spectral model. Using a joint analysis of the 7 degrees and 10 degrees ''cross''-rms derived from both the 53 and 90 GHz sky maps, we find Q(rms-PS) = 17.0-(+2.5)(2.1) mu K when the low quadrupole is included, and Q(rms-PS) = 19.4(+2.1)(+2.3) mu K excluding the quadrupole. These results are consistent with the n = 1 fits from more sensitive methods. The effect of the low quadrupole derived from the COBE-DMR data on the inferred Q(rms-PS) normalization is investigated. A bias to lower Q(rms-PS) is found when the quadrupole is included. The higher normalization for a forced n = 1 fit is then favored by the cross-rms technique. C1 UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,SSL,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CFPA,BERKELEY,CA 94720. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. HUGHES STX CORP,LANHAM,MD 20706. RP BANDAY, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,CODE 6853,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 11 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 1994 VL 436 IS 2 BP L99 EP L102 DI 10.1086/187642 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV554 UT WOS:A1994PV55400001 ER PT J AU SNOWDEN, SL PETRE, R AF SNOWDEN, SL PETRE, R TI AN X-RAY IMAGE OF THE LARGE MAGELLANIC CLOUD SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ISM; MAGELLANIC CLOUDS; TECHNIQUES, IMAGE PROCESSING; X-RAYS, GALAXIES; X-RAYS, ISM ID INTERSTELLAR-MEDIUM; ROSAT PSPC; 30-DORADUS; REMNANTS AB We have used archival ROSAT PSPC pointed observations to construct maps of the Large Magellanic Cloud in four energy bands between 0.5 and 2.0 keV. These represent the most complete, deepest, and most detailed X-ray images of the LMC to date. While confirming the general morphology of the diffuse LMC emission observed by Wang et al. with Einstein IPC data, these images reveal a wealth of detailed structure of high statistical significance on angular scales from a few arcminutes to a few degrees. In addition, at least twice as many discrete sources are detected as were found using the IPC. RP SNOWDEN, SL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,CODE 666,GREENBELT,MD 20771, USA. RI Snowden, Steven/D-5292-2012 NR 20 TC 42 Z9 42 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 DEC 1 PY 1994 VL 436 IS 2 BP L123 EP L126 DI 10.1086/187648 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV554 UT WOS:A1994PV55400007 ER PT J AU ZIURYS, LM APPONI, AJ HOLLIS, JM SNYDER, LE AF ZIURYS, LM APPONI, AJ HOLLIS, JM SNYDER, LE TI DETECTION OF INTERSTELLAR N2O - A NEW MOLECULE CONTAINING AN N-O BOND SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, ABUNDANCES; ISM, GALAXY, CENTER; ISM, MOLECULES; LINE, IDENTIFICATION ID NITRIC-OXIDE; CLOUD AB A new interstellar molecule, N2O, known as nitrous oxide or ''laughing gas,'' has been detected using the NRAO 12 m telescope. The J = 3 --> 2, 4 --> 3, 5 -->, 4, and 6 --> 5 rotational transitions of this species at 75, 100, 125, and 150 GHz, respectively, were observed toward Sgr B2(M). The column density derived for N,O in this source is N-lot similar to 10(15) cm(-2), which corresponds to a fractional abundance of similar to 10(-9), relative to H-2. This value implies abundance ratios of N2O/NO similar to 0.1 and N2O/HNO similar to 3 in the Galactic center. Such ratios are in excellent agreement with predictions of ion-molecule models of interstellar chemistry using early-time calculations and primarily neutral-neutral reactions. N,O is the third interstellar molecule detected thus far containing an N-O bond. Such bonds cannot be so rare as previously thought. C1 NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,GREENBELT,MD 20771. UNIV ILLINOIS,DEPT ASTRON,URBANA,IL 61801. RP ZIURYS, LM (reprint author), ARIZONA STATE UNIV,DEPT CHEM,TEMPE,AZ 85287, USA. NR 17 TC 29 Z9 29 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 DEC 1 PY 1994 VL 436 IS 2 BP L181 EP L184 DI 10.1086/187662 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV554 UT WOS:A1994PV55400021 ER PT J AU GOORVITCH, D AF GOORVITCH, D TI INFRARED CO LINE LIST FOR THE CHI(1)SIGMA(+) STATE SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE MOLECULAR DATA ID PARTITION-FUNCTIONS; OSCILLATOR-STRENGTHS; DUNHAM COEFFICIENTS; DIATOMIC-MOLECULES; GROUND-STATE; TRANSITIONS AB A complete line list with improved accuracy for all the rotation-vibration transitions of the fundamental, first, and second overtone bands up to v = 20 and J = 149 of the ground state X(1) Sigma(+) of the seven CO isotopes-(CO)-C-12-O-16, (CO)-C-13-O-16, (CO)-C-12-O-17, (CO)-C-12-O-18, (CO)-C-13-O-18, (CO)-C-14-O-16, and (CO)-C-13-O-17-is made available to the astronomical community. A line list of the pure rotational transitions up to v = 5 and J = 60 is also made available for these seven isotopes. This line list contains the transition frequency, the lower state energy, the Einstein A-value, the gf-value, the transition strength at 3000 K or 1000 K for the pure rotational transitions, the expectation value of the effective dipole moment operator, and the quantum numbers of each transition. Individual partition functions are reported in the temperature range of 500 to 10,000 K. This line list is available as four text files from the author using an anonymous ftp transfer and in computer-readable form in the AAS CD-ROM Series, Vol. 3. RP GOORVITCH, D (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 18 TC 191 Z9 191 U1 0 U2 9 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD DEC PY 1994 VL 95 IS 2 BP 535 EP 552 DI 10.1086/192110 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV390 UT WOS:A1994PV39000010 ER PT J AU SRIVASTAVA, KM TSURUTANI, BT AF SRIVASTAVA, KM TSURUTANI, BT TI NONLINEAR STABILITY OF HALLEY COMETOSHEATH WITH TRANSVERSE-PLASMA MOTION SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID COMET HALLEY; EQUATIONS AB Weakly nonlinear MHD stability of the Halley cometosheath determined by the balance between the outward ion-neutral drag force and the inward Lorentz force is investigated including the transverse plasma motion as observed in the flanks with the help of the method of multiple scales. The eigenvalues and the eigenfunctions are obtained for the linear problem and the time evolution of the amplitude is obtained using the solvability condition for the solution of the second order problem. The diamagnetic cavity boundary and the adjacent layer of about 100 km thickness is found unstable for the travelling waves of certain wave numbers. Halley ionopause has been observed to have strong ripples with a wavelength of several hundred kilometers. It is found that nonlinear effects have stabilizing effect. C1 UNIV DELHI,DEPT MATH,DELHI 110007,INDIA. CALTECH,JET PROP LAB,PASADENA,CA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD DEC PY 1994 VL 222 IS 1-2 BP 113 EP 125 DI 10.1007/BF00627087 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QD510 UT WOS:A1994QD51000009 ER PT J AU SINGH, HB AF SINGH, HB TI ATMOSPHERIC EFFECTS OF AVIATION - SUBSONIC AIRCRAFT SO ATMOSPHERIC ENVIRONMENT LA English DT Editorial Material RP SINGH, HB (reprint author), NASA,AMES RES CTR,DIV EARTH SYST SCI,MAIL STOP 245-5,MOFFETT FIELD,CA 94035, USA. NR 1 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 1352-2310 J9 ATMOS ENVIRON JI Atmos. Environ. PD DEC PY 1994 VL 28 IS 21 BP 3552 EP 3552 PG 1 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA PZ111 UT WOS:A1994PZ11100011 ER PT J AU CRANDALL, CG ENGELKE, KA PAWELCZYK, JA RAVEN, PB CONVERTINO, VA AF CRANDALL, CG ENGELKE, KA PAWELCZYK, JA RAVEN, PB CONVERTINO, VA TI POWER SPECTRAL AND TIME-BASED ANALYSIS OF HEART-RATE-VARIABILITY FOLLOWING 15 DAYS HEAD-DOWN BED REST SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID CARDIAC VAGAL TONE; RESPONSES; PRESSURE; ATROPINE AB Power spectral and time based analyses were applied to the cardiac inter beat interval (RRI) of 8 healthy men before and after 15 d of bed rest in the 6 degrees head-down tilt position (HPT) to determine changes in indices of cardiac parasympathetic and sympathetic activity after this exposure. At 24 h prior to HDT and on HDT day 15, a minimum of 256 RRI's were obtained from an electrocardiogram (ECG) while the subjects were in the supine position. RRI was subjected to power spectral and two methods of time-based analyses. Power spectral analysis demonstrated that the index of cardiac vagal activity wets reduced (95.2 +/- 28.5 to 48.2 +/- 17.4 ms(2)) without affecting the index of cardiac sympathetic activity (1.18 +/- 0.7 to 0.69 +/- 0.4). The two methods of time-based analyses, time series and standard deviation analyses, further demonstrated a reduction of cardiac vagal activity post-HDT (5.5 +/- 4 to 4.8 +/- 0.6 ms(2); and 42.8 +/- 4.8 to 33.9 +/- 3.3 ms, respectively). These data suggest that exposure to 15 d of HDT reduces cardiac vagal activity, while changes in cardiac sympathetic activity were indistinguishable. C1 TEXAS COLL OSTEOPATH MED,DEPT PHYSIOL,FT WORTH,TX 76107. NASA,KENNEDY SPACE CTR,FL. CLIN SCI DIV,PHYSIOL RES BRANCH,BROOKS AFB,TX. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 34 TC 32 Z9 34 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 DEC PY 1994 VL 65 IS 12 BP 1105 EP 1109 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PV821 UT WOS:A1994PV82100006 PM 7872911 ER PT J AU BERNAUER, EM WALBY, WF ERTL, AC DEMPSTER, PT BOND, M GREENLEAF, JE AF BERNAUER, EM WALBY, WF ERTL, AC DEMPSTER, PT BOND, M GREENLEAF, JE TI KNEE-JOINT PROPRIOCEPTION DURING 30-DAY 6-DEGREES HEAD-DOWN BED REST WITH ISOTONIC AND ISOKINETIC EXERCISE TRAINING SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB To determine if daily isotonic exercise or isokinetic exercise training coupled with daily leg proprioceptive training, would influence leg proprioceptive tracking responses during bed rest (BR), 19 men (36 +/- SD 4 years, 178 +/- 7 cm, 76.8 +/- 7.8 kg) were allocated into a no exercise (NOE) training control group (n = 5), and isotonic exercise (ITE, n = 7) and isokinetic exercise (IKE, n = 7) training groups. Exercise training was conducted during go for two 30-min periods . d(-1), 5 d . week(-1). Only the IKE group performed proprioceptive training using a new isokinetic procedure with each lower extremity for 2.5 min before and after the daily exercise training sessions; proprioceptive testing occurred weekly for all groups. There were no significant differences in proprioceptive tracking scores, expressed as a percentage of the perfect score of 100, in the pre-SR ambulatory control period between the three groups. Knee extension and flexion tracking responses were unchanged with NOE during BR, but were significantly greater (*p < 0.05) at the end of BR in both exercise groups when compared with NOE responses (extension: NOE 80.7 +/- 0.7%, ITE 82.9* +/- 0.6%, IKE 86.5* +/- 0.7%; flexion: NOE 77.6 +/- 1.5%, ITE 80.0 +/- 0.8% (NS), IKE 83.6* +/- 0.8%). Although proprioceptive tracking was unchanged during BR with NOE, both isotonic exercise training (without additional proprioceptive training) and especially isokinetic exercise training when combined with daily proprioceptive training, significantly improved knee proprioceptive tracking responses after 30 d of BR. C1 NASA,AMES RES CTR,DIV LIFE SCI 23911,HUMAN ENVIRONM PHYSIOL LAB,MOFFETT FIELD,CA 94035. UNIV CALIF DAVIS,HUMAN PERFORMANCE LAB,DAVIS,CA 95616. LOREDAN BIOMED,DAVIS,CA. NR 10 TC 17 Z9 20 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 DEC PY 1994 VL 65 IS 12 BP 1110 EP 1115 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PV821 UT WOS:A1994PV82100007 PM 7872912 ER PT J AU ADAMS, GR HATHER, BM DUDLEY, GA AF ADAMS, GR HATHER, BM DUDLEY, GA TI EFFECT OF SHORT-TERM UNWEIGHTING ON HUMAN SKELETAL-MUSCLE STRENGTH AND SIZE SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID LOWER-LIMB SUSPENSION; HUMAN QUADRICEPS; ADAPTATIONS; ACTIVATION; AREA AB This study examined the effect of short-term unweighting on strength and size of lower limb muscle groups to predict probable responses to planned 16-d Shuttle flights. Subjects were 10 healthy males, exposed to 16 d of lower limb suspension (LLS). All ambulatory activity wets performed on crutches while wearing a shoe with a IO-cm thick sole on the right foot. This eliminated ground contact by the left feet, and thereby, body weight bearing by the left lower limb. Biopsies of the left vastus lateralis muscle and T-1 weighted magnetic resonance (MR) images (1.5 Tesla, TR/TE 600/20, 4 nex, 48 cm rectangular FOV, 10 mm transaxial slices at 5-mm intervals) of both thighs were used to examine muscle morphology. The in vivo speed-torque relation for the left and right quadriceps femoris (QF) muscle group wets used to measure strength. Fiber type composition and average cross-sectional area were not altered by LLS. The speed-torque relation for the left QF was down-shifted 12% (p < 0.05) after LLS. There was no effect of speed or type of muscle action (eccentric, isometric, or concentric). The speed-torque relation for the right QF showed no change after LLS. Average cross-sectional area of the left QF in eight MR images of the mid-thigh decreased (p < 0.05) 8% with LLS (70 +/- 3 to 64 +/- 4 cm(2)), while the right QF showed no change (72 +/- 4 to 72 +/- 4 cm(2)). The hamstring muscle group showed no change in average cross-sectional area after LLS. The results suggest that 16 d of unweighting will evoke decreases in strength and ''size'' of lower limb extensor muscle groups in humans of sufficient magnitude to be operationally significant, that Is greater than 10%. Accordingly, it is sug gested that the planned 16-d Shuttle missions will be of sufficient duration to 1) warrant investigation of the effect of microgravity on certain aspects of the human neuromuscular system, and 2) potentially compromise ability of the crew to perform emergency egress. C1 NASA,BIONET CORP,BIOMED & ENVIRONM LABS,KENNEDY SPACE CTR,FL. NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL. NR 31 TC 66 Z9 67 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 DEC PY 1994 VL 65 IS 12 BP 1116 EP 1121 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PV821 UT WOS:A1994PV82100008 PM 7872913 ER PT J AU NICOGOSSIAN, AE AF NICOGOSSIAN, AE TI THE HUMAN SPACE ENTERPRISE IN THE 21ST-CENTURY SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article RP NICOGOSSIAN, AE (reprint author), NASA,OFF LIFE MICROGRAV SCI & APPLICAT,WASHINGTON,DC 20546, USA. NR 0 TC 1 Z9 2 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 DEC PY 1994 VL 65 IS 12 BP 1149 EP 1152 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PV821 UT WOS:A1994PV82100015 PM 7872920 ER PT J AU HERRON, JN TERRY, AH JOHNSTON, S HE, XM GUDDAT, LW VOSS, EW EDMUNDSON, AB AF HERRON, JN TERRY, AH JOHNSTON, S HE, XM GUDDAT, LW VOSS, EW EDMUNDSON, AB TI HIGH-RESOLUTION STRUCTURES OF THE 4-4-20-FAB FLUORESCEIN COMPLEX IN 2-SOLVENT SYSTEMS - EFFECTS OF SOLVENT ON STRUCTURE END ANTIGEN-BINDING AFFINITY SO BIOPHYSICAL JOURNAL LA English DT Article ID INFLUENZA-VIRUS NEURAMINIDASE; PROCESSES INVOLVING PROTEINS; REGION PRIMARY STRUCTURES; MOLAR HEAT-CAPACITY; AMINO-ACID-RESIDUES; 3-DIMENSIONAL STRUCTURE; CRYSTAL-STRUCTURE; CRYSTALLOGRAPHIC ANALYSIS; PEPTIDE ANTIGEN; CYCLOSPORINE-A AB Three-dimensional structures were determined for three crystal forms of the antigen binding fragment (Fab) of anti-fluorescein antibody 4-4-20 in complex with fluorescein. These included 1) a triclinic (P1) form crystallized in 47% (v/v) 2-methyl-2,4-pentanediol (MPD); 2) a triclinic (P1) form crystallized in 16% (v/v) poly(ethylene glycol), molecular weight 3350 (PEG); and 3) a monoclinic (P2(1)) form crystallized in 16% PEG, Solvent molecules were added to the three models and the structures were refined to their diffraction limits (1.75-Angstrom, 1.78-Angstrom, and 2.49-Angstrom resolution for the MPD, triclinic PEG, and monoclinic PEG forms, respectively). Comparisons of these structures were interesting because 4-4-20 exhibited a lower antigen-binding affinity in 47% MPD (K-a = 1.3 x 10(8) M(-1)) than in either 16% PEG (K-a = 2.9 x 10(9) M(-1)) or phosphate-buffered saline (K-a = 1.8 x 10(10) M-l), Even though the solution behavior of the antibody was significantly different in MPD and PEG, the crystal structures were remarkably similar. In all three structures, the fluorescein-combining site was an aromatic slot formed by tyrosines L32, H96, and H97 and tryptophans L96 and H33. in addition, several active site constituents formed an electrostatic network with the ligand. These included a salt link between arginine L34 and one of fluorescein's enolate oxygen atoms, a hydrogen bond between histidine L27d and the second enolic group, a hydrogen bond between tyrosine L32 and the phenylcarboxylate group, and two medium range (similar to 5 Angstrom) electrostatic interactions with lysine L50 and arginine H52. The only major difference between the triclinic MPD and PEG structures was the degree of hydration of the antigen-combining site. Three water molecules participated in the above electrostatic network in the MPD structure, while eight were involved in the PEG structure. Based on this observation, we believe that 4-4-20 exhibits a lower affinity in MPD due to the depletion of the hydration shell of the antigen-combining site. C1 UNIV UTAH, DEPT PHARMACEUT & PHARMACEUT CHEM, SALT LAKE CITY, UT 84112 USA. HARRINGTON CANC CTR, AMARILLO, TX USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. UNIV ILLINOIS, DEPT MICROBIOL, URBANA, IL 61801 USA. OI Guddat, Luke/0000-0002-8204-8408 FU NIAID NIH HHS [AI 22898] NR 70 TC 69 Z9 70 U1 0 U2 0 PU CELL PRESS PI CAMBRIDGE PA 600 TECHNOLOGY SQUARE, 5TH FLOOR, CAMBRIDGE, MA 02139 USA SN 0006-3495 EI 1542-0086 J9 BIOPHYS J JI Biophys. J. PD DEC PY 1994 VL 67 IS 6 BP 2167 EP 2183 PG 17 WC Biophysics SC Biophysics GA PV061 UT WOS:A1994PV06100007 PM 7696460 ER PT J AU VAUGHAN, WW JOHNSON, DL AF VAUGHAN, WW JOHNSON, DL TI METEOROLOGICAL SATELLITES - THE VERY EARLY YEARS, PRIOR TO LAUNCH OF TIROS-1 SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article AB The meteorological satellite program began in the United States as the result of the actions taken by a very small but dedicated group of people from the late 1940s to 1960. This paper provides firsthand accounts by two of these dedicated individuals. Their remarks provide an insight into the trials and tribulations they and the program encountered during these very early years. Those now active in the program, many of whom do not recall this time, might appreciate the effort of these pioneers and the legacy they left for us. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP VAUGHAN, WW (reprint author), UNIV ALABAMA,ATMOSPHER SCI PROGRAMM,HUNTSVILLE,AL 35899, USA. NR 26 TC 4 Z9 4 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD DEC PY 1994 VL 75 IS 12 BP 2295 EP 2302 DI 10.1175/1520-0477(1994)075<2295:MSVEYP>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QB544 UT WOS:A1994QB54400004 ER PT J AU PENNER, JE CHARLSON, RJ HALES, JM LAULAINEN, NS LEIFER, R NOVAKOV, T OGREN, J RADKE, LF SCHWARTZ, SE TRAVIS, L AF PENNER, JE CHARLSON, RJ HALES, JM LAULAINEN, NS LEIFER, R NOVAKOV, T OGREN, J RADKE, LF SCHWARTZ, SE TRAVIS, L TI QUANTIFYING AND MINIMIZING UNCERTAINTY OF CLIMATE FORCING BY ANTHROPOGENIC AEROSOLS - COMMENT - REPLY SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Letter ID NITRATE CONCENTRATIONS; SULFATE C1 UNIV WASHINGTON, SEATTLE, WA 98195 USA. PACIFIC NW LAB, RICHLAND, WA USA. ENVIRONM MEASUREMENTS LAB, NEW YORK, NY USA. UNIV CALIF BERKELEY, LAWRENCE BERKELEY LAB, BERKELEY, CA USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. BROOKHAVEN NATL LAB, UPTON, NY 11973 USA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. ENVAIR, RICHLAND, WA USA. RP PENNER, JE (reprint author), LAWRENCE LIVERMORE NATL LAB, LIVERMORE, CA USA. RI Schwartz, Stephen/C-2729-2008; Penner, Joyce/J-1719-2012 OI Schwartz, Stephen/0000-0001-6288-310X; NR 11 TC 1 Z9 1 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD DEC PY 1994 VL 75 IS 12 BP 2315 EP 2316 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QB544 UT WOS:A1994QB54400007 ER PT J AU PALEY, MS FRAZIER, DO ABDELDAYEM, H MCMANUS, SP AF PALEY, MS FRAZIER, DO ABDELDAYEM, H MCMANUS, SP TI PHOTODEPOSITION OF THIN POLYDIACETYLENE FILMS FROM SOLUTION THAT EXHIBIT LARGE 3RD-ORDER OPTICAL NONLINEARITIES SO CHEMISTRY OF MATERIALS LA English DT Note AB A novel technique has been developed for preparing thin amorphous films of a polydiacetylene derivative of 2-methyl-4-nitroaniline (MNA) using photodeposition from monomer solutions. This heretofore unknown process yields films that possess very high optical quality and exhibit large third-order nonlinear optical susceptibilities (10(-8)-10(-7) esu). Photodeposition can also be carried out using lasers to form thin optical circuits. This could eventually make the application of polydiacetylene thin films for nonlinear optical devices such as waveguides and integrated optics more commercially feasible. C1 UNIV ALABAMA,PROGRAM MAT SCI,HUNTSVILLE,AL 35899. RP PALEY, MS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 7 TC 8 Z9 8 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0897-4756 J9 CHEM MATER JI Chem. Mat. PD DEC PY 1994 VL 6 IS 12 BP 2213 EP 2215 DI 10.1021/cm00048a005 PG 3 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA PY663 UT WOS:A1994PY66300005 ER PT J AU TAI, H AF TAI, H TI GENERALIZED-METHOD FOR SOLVING MULTICENTER MOLECULAR INTEGRALS OF SLATER-TYPE ORBITALS SO CHINESE JOURNAL OF PHYSICS LA English DT Article DE GENERAL MATHEMATICAL AND COMPUTATIONAL DEVELOPMENTS; COMPUTATIONAL TECHNIQUES (FOR DATA HANDLING AND COMPUTATION) AB By introducing irreducible tensorial operators, the recently developed method of solving multi-center molecular integrals by coupling the two-center exchange integrals with a Fourier transform scheme is further generalized to handle any Slater type orbitals of arbitrarily higher angular momentum states. Numerical procedures can be applied to the final expressions to obtain numerical results. RP TAI, H (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 15 TC 3 Z9 3 U1 0 U2 1 PU PHYSICAL SOC REPUBLIC CHINA PI TAIPEI PA CHINESE JOURNAL PHYSICS PO BOX 23-30, TAIPEI 10764, TAIWAN SN 0577-9073 J9 CHINESE J PHYS JI Chin. J. Phys. PD DEC PY 1994 VL 32 IS 6 BP 847 EP 862 PN 1 PG 16 WC Physics, Multidisciplinary SC Physics GA PW108 UT WOS:A1994PW10800005 ER PT J AU HEYLIGER, P RAMIREZ, G SARAVANOS, D AF HEYLIGER, P RAMIREZ, G SARAVANOS, D TI COUPLED DISCRETE-LAYER FINITE-ELEMENTS FOR LAMINATED PIEZOELECTRIC PLATES SO COMMUNICATIONS IN NUMERICAL METHODS IN ENGINEERING LA English DT Article ID SENSORS ACTUATORS; COMPOSITES; DESIGN AB Finite element models based on discrete-layer theories are presented for the coupled-field analysis of laminated plates containing piezoelectric layers. The three displacements and the electrostatic potential are treated as unknowns in this formulation, which allows for piece-wise approximations of the variables through the thickness of each layer. Two specific models are demonstrated in which the transverse displacement is either variable or constant, and the in-plane displacements and potential take piece-wise linear approximations through the thickness. The models are applied to example problems with applied surface tractions and specified surface potentials. Good agreement is found with exact solutions. C1 NASA,LEWIS RES CTR,OHIO RES INST,STRUCH MECH BRANCH,CLEVELAND,OH 44135. RP HEYLIGER, P (reprint author), COLORADO STATE UNIV,DEPT CIVIL ENGN,FT COLLINS,CO 80523, USA. NR 18 TC 80 Z9 80 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 1069-8299 J9 COMMUN NUMER METH EN JI Commun. Numer. Methods Eng. PD DEC PY 1994 VL 10 IS 12 BP 971 EP 981 DI 10.1002/cnm.1640101203 PG 11 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA QF651 UT WOS:A1994QF65100002 ER PT J AU TOOMARIAN, N FIJANY, A BARHEN, J AF TOOMARIAN, N FIJANY, A BARHEN, J TI TIME-PARALLEL SOLUTION OF LINEAR PARTIAL-DIFFERENTIAL EQUATIONS ON THE INTEL TOUCHSTONE DELTA SUPERCOMPUTER SO CONCURRENCY-PRACTICE AND EXPERIENCE LA English DT Article AB The paper presents the implementation of a new class of massively parallel algorithms for solving certain time-dependent partial differential equations (PDEs) on massively parallel supercomputers. Such PDEs are usually solved numerically, by discretization in time and space, and by applying a time-stepping procedure to data and algorithms potentially parallelized in the spatial domain. In a radical departure from such a strictly sequential temporal paradigm, we have developed a concept of time-parallel algorithms, which allows the marching in time to be fully parallelized. This is achieved by using a set of transformations based on eigenvalue-eigenvector decomposition of the matrices involved in the discrete formalism. Our time-parallel algorithms possess a highly decoupled structure, and can therefore be efficiently implemented on emerging, massively parallel, high-performance supercomputers, with a minimum of communication and synchronization overhead. We have successfully carried out a proof-of-concept demonstration of the basic ideas using a two-dimensional heat equation example implemented on the Intel Touchstone Delta supercomputer. Our results indicate that linear, and even superlinear, speed-up can be achieved and maintained for a very large number of processor nodes. C1 JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. NR 19 TC 1 Z9 1 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 1040-3108 J9 CONCURRENCY-PRACT EX JI Concurrency-Pract. Exp. PD DEC PY 1994 VL 6 IS 8 BP 641 EP 652 DI 10.1002/cpe.4330060803 PG 12 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA PT043 UT WOS:A1994PT04300002 ER PT J AU POPE, KO BAINES, KH OCAMPO, AC IVANOV, BA AF POPE, KO BAINES, KH OCAMPO, AC IVANOV, BA TI IMPACT WINTER AND THE CRETACEOUS-TERTIARY EXTINCTIONS - RESULTS OF A CHICXULUB ASTEROID IMPACT MODEL SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Letter ID TERTIARY EXTINCTION; CRATER; BOLIDE; EARTH AB The Chicxulub impact crater in Mexico is the site of the impact purported to have caused mass extinctions at the Cretaceous/Tertiary (K/T) boundary. 2-D hydrocode modeling of the impact, coupled with studies of the impact site geology, indicate that between 0.4 and 7.0 x 10(17) g of sulfur were vaporized by the impact into anhydrite target rocks. A small portion of the sulfur was released as SO3 or SO4, which converted rapidly into H2SO4 aerosol and fell as acid rain. A radiative transfer model, coupled with a model of coagulation indicates that the aerosol prolonged the initial blackout period caused by impact dust only if the aerosol contained impurities. A larger portion of sulfur was released as SO2, which converted to aerosol slowly, due to the rate-limiting oxidation of SO2. Our radiative transfer calculations, combined with rates of acid production, coagulation, and diffusion indicate that solar transmission was reduced to 10-20% of normal for a period of 8-13 yr. This reduction produced a climate forcing (cooling) of -300 Wm(-2) which far exceeded the +8 Wm(-2) greenhouse warming, caused by the CO2 released through the vaporization of carbonates, and therefore produced a decade of freezing and near-freezing temperatures. Several decades of moderate warming followed the decade of severe cooling due to the long residence time of CO2. The prolonged impact winter may have been a major cause of the K/T extinctions. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RUSSIAN ACAD SCI,INST DYNAM GEOSPHERES,MOSCOW,RUSSIA. RP POPE, KO (reprint author), GEO ECO ARC RES,2222 FOOTHILL BLVD,SUITE E-272,LA CANADA FLINTRIDGE,CA 91011, USA. RI Ivanov, Boris/E-1413-2016 OI Ivanov, Boris/0000-0002-9938-9428 NR 37 TC 93 Z9 96 U1 4 U2 24 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD DEC PY 1994 VL 128 IS 3-4 BP 719 EP 725 DI 10.1016/0012-821X(94)90186-4 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QC238 UT WOS:A1994QC23800053 PM 11539442 ER PT J AU RAMACHANDRAN, N HEAMAN, J SMITH, A AF RAMACHANDRAN, N HEAMAN, J SMITH, A TI AN EXPERIMENTAL-STUDY OF THE FLOW EMERGING FROM POROUS WALLS SO EXPERIMENTS IN FLUIDS LA English DT Article AB The fluid mechanics of air flow exiting from porous materials is investigated. Porous walls with filter ratings differing by about three orders of magnitude are studied. The flow behavior is investigated for its spatial and temporal stability. The measurements show that coalescence effects cause jet development which gives rise to a stable, spatial velocity nonuniformity termed pseudo-turbulence. Beyond a critical mean velocity, the pseudo-turbulence shows a leveling trend and the flow exhibits jets whose dimensions are independent of wall porosity and provide a unique length scale for this type of flow field (almost-equal-to 1 mm). A correlation is developed to predict the onset of fully developed jets. The impact of using porous wall materials in cold flow solid rocket motor testing is addressed. RP RAMACHANDRAN, N (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,ED 36,BLDG 4732,HUNTSVILLE,AL 35812, USA. NR 17 TC 1 Z9 1 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD DEC PY 1994 VL 18 IS 1-2 BP 119 EP 128 PG 10 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA PX823 UT WOS:A1994PX82300014 ER PT J AU SHAO, GF SCHALL, P WEISHAMPEL, JF AF SHAO, GF SCHALL, P WEISHAMPEL, JF TI DYNAMIC SIMULATIONS OF MIXED BROADLEAVED PINUS-KORAIENSIS FORESTS IN THE CHANGBAISHAN BIOSPHERE RESERVE OF CHINA SO FOREST ECOLOGY AND MANAGEMENT LA English DT Article DE GAP MODEL; REGENERATION; SUCCESSION; TIMBER HARVEST ID SUCCESSION; CLIMATE; PATTERN; GROWTH; MODEL; SCALE AB The development of mixed broadleaved-Korean pine (Pinus koraiensis Sieb. et Zucc.) forests in the Changbaishan Biosphere Reserve, located on the border with North Korea, was simulated using the gap model KOPIDE. Forest succession was simulated under three initial conditions from: (1) bare ground after clearcutting; (2) secondary forest; (3) old-growth forest. The simulations from the different initial conditions converged and support earlier successional theory that Korean pine is the climax species on the highlands of northeast China even under disturbed conditions. In addition to clear-cutting, the resilience of the forest to different levels of other human impacts, pine seed harvesting and selective cutting, was examined. These results further demonstrate that these forests possess a relatively stable structure characterized by the dominance of Korean pine. However, the model showed successional processes of the forest to be susceptible to high levels of pine seed harvesting. To predict forest dynamics at landscape scales, KOPIDE was linked with a Geographical Information System containing site and stand data sets. Running this model to simulate a forested area initially comprising several successional stages suggests that, in the absence of disturbance, Korean pine is likely to become increasingly dominant on the area over the next century. C1 CHINESE ACAD SCI,INST APPL ECOL,SHENYANG 110015,PEOPLES R CHINA. TECH UNIV MUNICH,LEHRSTUHL LANDSCHAFTSOKOL,W-8050 FREISING 12,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. OI Schall, Peter/0000-0003-4808-818X NR 25 TC 45 Z9 59 U1 3 U2 18 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-1127 J9 FOREST ECOL MANAG JI For. Ecol. Manage. PD DEC PY 1994 VL 70 IS 1-3 BP 169 EP 181 DI 10.1016/0378-1127(94)90084-1 PG 13 WC Forestry SC Forestry GA QC199 UT WOS:A1994QC19900015 ER PT J AU KELLER, LP THOMAS, KL CLAYTON, RN MAYEDA, TK DEHART, JM MCKAY, DS AF KELLER, LP THOMAS, KL CLAYTON, RN MAYEDA, TK DEHART, JM MCKAY, DS TI AQUEOUS ALTERATION OF THE BALI CV3 CHONDRITE - EVIDENCE FROM MINERALOGY, MINERAL CHEMISTRY, AND OXYGEN ISOTOPIC COMPOSITIONS SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID TRANSMISSION ELECTRON-MICROSCOPE; CARBONACEOUS CHONDRITE; ALLENDE METEORITE; OLIVINE; MATRIX; SURFACE; ORIGIN AB A petrographic, geochemical, and oxygen isotopic study of the Ball CV3 carbonaceous chondrite revealed that the meteorite has undergone extensive deformation and aqueous alteration on its parent body. Deformation textures are common and include flattened chondrules, a well-developed foliation, and the presence of distinctive (100) planar defects in olivine. The occurrence of alteration products associated with the planar defects indicates that the deformation features formed prior to the episode of aqueous alteration. The secondary minerals produced during the alteration event include well-crystallized Mg-rich saponite, framboidal magnetite, and Ca-phosphates. The alteration products are not homogeneously distributed throughout the meteorite, but occur in regions adjacent to relatively unaltered material, such as Veins of altered material following the foliation. The alteration assemblage formed under oxidizing conditions at relatively low temperatures (<100 degrees C). Altered regions in Ball have higher Na, Ca, and P contents than unaltered regions which suggests that the fluid phase carried significant dissolved solids. Oxygen isotopic compositions for unaltered regions in Bail fall within the field for other CV3 whole-rocks, however, the oxygen isotopic compositions of the heavily altered material lie in the region for the CM and CR chondrites. The heavy-isotope enrichment of the altered regions in Ball suggest alteration conditions similar to those for the petrographic type-2 carbonaceous chondrites. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. NASA,LYNDON B JOHNSON SPACE CTR,SN,HOUSTON,TX 77058. RP KELLER, LP (reprint author), MVA INC,5500 OAKBROOK PKWY,SUITE 200,NORCROSS,GA 30093, USA. NR 30 TC 67 Z9 67 U1 0 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 DEC PY 1994 VL 58 IS 24 BP 5589 EP 5598 DI 10.1016/0016-7037(94)90252-6 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PY693 UT WOS:A1994PY69300017 PM 11539152 ER PT J AU COHEN, SC AF COHEN, SC TI EVALUATION OF THE IMPORTANCE OF MODEL FEATURES FOR CYCLIC DEFORMATION DUE TO DIP-SLIP FAULTING SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE ASTHENOSPHERE; DEFORMATION; FAULT SLIP; RHEOLOGY; SUBDUCTION ID EARTHQUAKE CYCLE; CRUSTAL DEFORMATION; DISLOCATION MODEL; SUBDUCTION ZONES; CALIFORNIA AB Finite-element techniques are used to investigate models of cyclic deformation on dip-slip faults. The models are based largely on the conceptual formulations of Matsu'ura and Sate (1989), Savage (1983), and Thatcher and Rundle (1984). We investigate the interaction of rheology, fault geometry, mechanical structure, non-tectonic forces, and the earthquake recurrence interval. The interaction of gravity and viscoelastic flow is complex. For example, if the asthenosphere is very weak, then regions that rise rapidly after an earthquake may subsequently subside due to isostatic readjustment. By contrast, if the asthenosphere is more viscous, uplifted regions may continue to grow throughout the earthquake cycle. The magnitude and width of regions of both uplift and subsidence depend on density, viscosity and viscoelastic channel thicknesses. The inclusion of plate bending appears to be important in earthquake modelling at subduction zones. The steady-state convergence of plates may lead to net vertical motion in the subduction zone. RP COHEN, SC (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GEODYNAM BRANCH, GREENBELT, MD 20771 USA. NR 17 TC 22 Z9 22 U1 0 U2 2 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD DEC PY 1994 VL 119 IS 3 BP 831 EP 841 DI 10.1111/j.1365-246X.1994.tb04020.x PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PW398 UT WOS:A1994PW39800013 ER PT J AU COLLINS, ML STANFORD, JL HALPERN, D AF COLLINS, ML STANFORD, JL HALPERN, D TI ONE-MONTH TO 2-MONTH OSCILLATIONS IN SSMI SURFACE WIND-SPEED IN WESTERN TROPICAL PACIFIC-OCEAN SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MICROWAVE AB The 10-m wind speed over the ocean can be estimated from microwave brightness temperature measurements recorded by the Special Sensor Microwave Imager (SSMI) instrument mounted on a polar-orbiting spacecraft. Four-year (1988 - 1991) time series of average daily 1 degrees x 1 degrees SSMI wind speeds were analyzed at selected sites in the western tropical Pacific Ocean. One- to two-month period wind speed oscillations with amplitudes statistically significant at the 95% confidence level were observed near Kanton, Eniwetok, Guam, and Truk. This is the first report of such an oscillation in SSMI wind speeds. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP COLLINS, ML (reprint author), IOWA STATE UNIV SCI & TECHNOL,DEPT PHYS & ASTRON,AMES,IA 50011, USA. NR 11 TC 0 Z9 0 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 DEC 1 PY 1994 VL 21 IS 24 BP 2685 EP 2688 DI 10.1029/94GL02439 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PV803 UT WOS:A1994PV80300019 ER PT J AU DELGENIO, AD KOVARI, W YAO, MS AF DELGENIO, AD KOVARI, W YAO, MS TI CLIMATIC IMPLICATIONS OF THE SEASONAL-VARIATION OF UPPER TROPOSPHERE WATER-VAPOR SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Satellite observations indicate that the humidity of the upper troposphere is higher in summer than in winter. We use general circulation model (GCM) simulations to explore the processes that maintain upper troposphere water vapor and determine its seasonal cycle. In the subtropics, drying by Hadley cell subsidence and stratiform condensation is offset primarily by moistening by eddies, with moist convection playing a minor role. Elsewhere, both mean meridional circulation and eddies moisten the upper troposphere and are balanced primarily by stratiform condensation drying. The effect of the seasonal shift of the Hadley cell is limited to latitudes equatorward of 30 degrees. At higher latitudes where the largest observed summer moistening occurs, eddy moisture fluxes are primarily responsible despite the eddies being weaker in summer than winter. The same mechanism causes upper level humidity to increase in GCM climate warming simulations. The observed seasonal variation may thus be a good proxy for decadal climate change. This suggests that upper troposphere water vapor feedback is positive at all latitudes, consistent with GCM predictions. C1 SCI SYST & APPLICAT INC,INST SPACE STUDIES,NEW YORK,NY 10025. RP DELGENIO, AD (reprint author), NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. RI Del Genio, Anthony/D-4663-2012 OI Del Genio, Anthony/0000-0001-7450-1359 NR 12 TC 37 Z9 37 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 DEC 1 PY 1994 VL 21 IS 24 BP 2701 EP 2704 DI 10.1029/94GL02658 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PV803 UT WOS:A1994PV80300023 ER PT J AU CHATFIELD, RB AF CHATFIELD, RB TI ANOMALOUS HNO3/NOX RATIO OF REMOTE TROPOSPHERIC AIR - CONVERSION OF NITRIC-ACID TO FORMIC-ACID AND NOX SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OBSERVATORY PHOTOCHEMISTRY EXPERIMENT; OZONE; MODEL; SIMULATIONS; CHEMISTRY; AEROSOLS; NITRATE; RATES AB The N oxidation ratio, [HNO3]/[NOx], in the free troposphere is measured at similar to 1 to 9 (averaging similar to 5), consistently lower than the values of 15-100 which known theory suggests to be reached rapidly. This discrepancy casts doubt on current models' abilities to predict effects of NO sources on remote [NO], and so also [O-3] and [OH]. HNO3-to-NOx, recycling processes involving HCHO in solution are appealing explanations for the ratio. Known chemical theory are illustrated using a Lagrangian box model of the mid-troposphere which simulates characteristic episodes from NOx input to HNO3 washout. Ratio and budget constraint equations for NOy can usefully restrict conceivable explanations of missing chemistry of fast nitrogen cycling; most explanations could be called ''fast-cycles'' or ''re-NOx-ification.'' These equations also show how current global models may suggest spuriously good N oxidation ratios and errors in OH. Aerosol or cloud droplets reactions with HCHO may produce (a) formic acid (which needs an appropriate source) and NOx, or alternatively, (b) hydroxymethyl nitrate (or methyl dinitrate), which might supply a large, variable amount of ''missing NOy not currently measurable except by NOy instruments. RP CHATFIELD, RB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 32 TC 96 Z9 96 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 DEC 1 PY 1994 VL 21 IS 24 BP 2705 EP 2708 DI 10.1029/94GL02659 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PV803 UT WOS:A1994PV80300024 ER PT J AU HINES, CO TARASICK, DW AF HINES, CO TARASICK, DW TI AIRGLOW RESPONSE TO VERTICALLY STANDING GRAVITY-WAVES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DRIVEN FLUCTUATIONS; NIGHT AIRGLOW; OH NIGHTGLOW; EMISSION; TEMPERATURES; CHEMISTRIES; ATMOSPHERE; REGION AB There is currently much interest in fluctuations of airglow emissions caused by atmospheric gravity waves. The fluctuations of brightness tend to be found in phase (or occasionally in antiphase) with the fluctuations of measured temperature, whereas current theory tends to anticipate substantial phase differences. We suggest here that the discrepancy results from failure of the common theoretical assumption that the relevant gravity waves are dominated by a single upgoing component: that, instead, there is an accompanying downgoing component of comparable magnitude, produced by reflection. In the case of total reflection, simple, steady state chemistry and vertical viewing, the phase difference is necessarily zero (or 180 degrees). C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. ATMOSPHER ENVIRONM SERV,N YORK M3H 5T4,ON,CANADA. OI Tarasick, David/0000-0001-9869-0692 NR 19 TC 21 Z9 21 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 DEC 1 PY 1994 VL 21 IS 24 BP 2729 EP 2732 DI 10.1029/94GL01137 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PV803 UT WOS:A1994PV80300030 ER PT J AU LOCKWOOD, M ONSAGER, TG DAVIS, CJ SMITH, MF DENIG, WF AF LOCKWOOD, M ONSAGER, TG DAVIS, CJ SMITH, MF DENIG, WF TI THE CHARACTERISTICS OF THE MAGNETOPAUSE RECONNECTION X-LINE DEDUCED FROM LOW-ALTITUDE SATELLITE-OBSERVATIONS OF CUSP IONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOSPHERE; PLASMA; MANTLE AB We present an analysis of a ''quasi-steady'' cusp ion dispersion signature observed at low altitudes. We reconstruct the field-parallel part of the Cowley-D ion distribution function, injected into the open LLBL in the vicinity of the reconnection X-line. From this we find the field-parallel magnetosheath flow at the X-line was only 20 +/- 60 km s(-1), placing the reconnection site close to the flow streamline which is perpendicular to the magnetosheath held. Using interplanetary data and assuming the subsolar magnetopause is in pressure balance, we derive a wealth of information about the X-line, including: the density, how magnetic field and Alfven speed of the magnetosheath; the magnetic shear across the X-line; the de-Hoffman Teller speed with which field lines emerge from the X-line; the magnetospheric field; and the ion transmission factor across the magnetopause. The results indicate that some heating takes place near the X-line as the ions cross the magnetopause, and that sheath densities may be reduced in a plasma depletion layer. We also compute the reconnection rate. Despite its quasi-steady appearance on an ion spectrogram, this cusp is found to reveal a large pulse of enhanced reconnection rate. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV NEW HAMPSHIRE,CTR SPACE SCI,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824. PHILLIPS LAB,GPSG,HANSCOM AFB,BEDFORD,MA 01731. UNIV NEW HAMPSHIRE,DEPT PHYS,DURHAM,NH 03824. RP LOCKWOOD, M (reprint author), RUTHERFORD APPLETON LAB,DIDCOT OX11 0QX,OXON,ENGLAND. RI Lockwood, Mike/G-1030-2011; Scott, Christopher/H-8664-2012 OI Lockwood, Mike/0000-0002-7397-2172; Scott, Christopher/0000-0001-6411-5649 NR 11 TC 25 Z9 25 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 DEC 1 PY 1994 VL 21 IS 24 BP 2757 EP 2760 DI 10.1029/94GL02696 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PV803 UT WOS:A1994PV80300037 ER PT J AU CORONITI, FV GREENSTADT, EW MOSES, SL TSURUTANI, BT SMITH, EJ AF CORONITI, FV GREENSTADT, EW MOSES, SL TSURUTANI, BT SMITH, EJ TI ON THE ABSENCE OF PLASMA-WAVE EMISSIONS AND THE MAGNETIC-FIELD ORIENTATION IN THE DISTANT MAGNETOSHEATH SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EARTHS BOW SHOCK; ISEE AB In early September, 1983 ISEE3 made a long traversal of the distant dawnside magnetosheath starting near x = -150 R(E) downstream. The distant magnetosheath often contains moderately intense plasma wave emissions at frequencies from several hundred Hz to 5 kHz. However, over time scales of many days, a clear correlation exists between the occurrence of the plasma waves and the cone angle (theta(xB)) between the magnetic field and the plasma flow velocity (x-direction). For theta(xB) large (small), the plasma wave amplitudes are near background (high). Sudden(< 1 minute) changes in the local magnetic field orientation produce correspondingly sudden changes in the wave amplitudes. Statistically, the wave amplitudes decrease continuously with increasing theta(xB). C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CORONITI, FV (reprint author), TRW CO INC,SPACE & TECHNOL GRP,1 SPACE PK,REDONDO BEACH,CA 90278, USA. NR 7 TC 4 Z9 4 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 DEC 1 PY 1994 VL 21 IS 24 BP 2761 EP 2764 DI 10.1029/94GL01583 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PV803 UT WOS:A1994PV80300038 ER PT J AU SLAVIN, JA OWEN, CJ HESSE, M AF SLAVIN, JA OWEN, CJ HESSE, M TI EVOLUTION OF THE PLASMOID-LOBE INTERACTION WITH DOWNTAIL DISTANCE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TRAVELING COMPRESSION REGIONS; GEOMAGNETIC TAIL; ISEE-3; MAGNETOTAIL; SHEET AB This study examines the interaction between plasmoids moving anti-sunward at high speeds and the tail lobes which bound them to the north and south. Attention is focused on the influence of changing lobe conditions with downtail distance. It is shown using ISEE 3 measurements that the gradual filling of the lobes with mantle plasma and the decrease in magnetic field intensity reduces the average lobe MHD fast mode speed from 1200 km s(-1) at X = -80 R(E) to 400 km s(-1) at X = -220 R(E). This results in the ratio of the plasmoid speed to the fast mode speed increasing with downtail distance, from 0.3 at X = -80 R(E) to similar to 1 at X = -220 R(E). It is argued that the ''standard'' traveling compression region (TCR) signature observed closer to the Earth will be distorted at large distances, where the fast mode transit time between the plasmoid and magnetopause becomes long compared to the time for the plasmoid to move past a given point in the tail. This change in the nature of the plasmoid-lobe interaction with downtail. distance is offered as an explanation for why the reported rate of TCR occurrence peaks at X = -60 to -130 R(E) and decreases in the more distant tail. RP SLAVIN, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Owen, Christopher/C-2999-2008; Hesse, Michael/D-2031-2012; Slavin, James/H-3170-2012 OI Owen, Christopher/0000-0002-5982-4667; Slavin, James/0000-0002-9206-724X NR 13 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 1994 VL 21 IS 24 BP 2765 EP 2768 DI 10.1029/94GL02442 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PV803 UT WOS:A1994PV80300039 ER PT J AU POORE, RZ CHANDLER, MA AF POORE, RZ CHANDLER, MA TI SIMULATING PAST CLIMATES - THE DATA-MODEL CONNECTION SO GLOBAL AND PLANETARY CHANGE LA English DT Editorial Material ID NORTH-ATLANTIC OCEAN; PLIOCENE C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP POORE, RZ (reprint author), US GEOL SURVEY,NATL CTR,MS 955,RESTON,VA 22092, USA. NR 7 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD DEC PY 1994 VL 9 IS 3-4 BP 165 EP 167 DI 10.1016/0921-8181(94)90014-0 PG 3 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA PZ127 UT WOS:A1994PZ12700001 ER PT J AU CHANDLER, M RIND, D THOMPSON, R AF CHANDLER, M RIND, D THOMPSON, R TI JOINT INVESTIGATIONS OF THE MIDDLE PLIOCENE CLIMATE .2. GISS GCM NORTHERN-HEMISPHERE RESULTS SO GLOBAL AND PLANETARY CHANGE LA English DT Article ID CLOUD OPTICAL-THICKNESS; DOUBLED CO2 CLIMATE; HEAT TRANSPORTS; ATMOSPHERIC MODEL; HIGHER HIMALAYAS; 2-PHASE UPLIFT; ICE-AGE; 17 MA; PALEOCLIMATE; OCEAN AB Marine microfaunal data and terrestrial pollen records indicate that the middle Pliocene (ca. 3 Ma) climate is the most recent period in geologic history with global temperatures nearly as warm as those predicted for the coming century. We used the GISS GCM to examine the Pliocene climate by specifying sea surface temperatures and vegetation distributions derived from U.S.G.S. data sets. The simulation resulted in 1.4 degrees C warming, annually averaged over the Northern Hemisphere. Warming was greatest at high latitudes; consequently, the equator to pole temperature gradient decreased by 11.5 degrees C. Surface air temperature increases were greatest in winter, as decreased snow and sea ice triggered a positive albedo feedback effect. At low latitudes, temperatures were mostly unchanged except for an anomalous 3 degrees C cooling over eastern Africa. This anomaly is supported by palynological data and, in the simulation, was a response to the weakening of the Hadley circulation, which caused subtropical clouds and evapotranspiration rates to increase. Evaporation and precipitation rates decreased over the oceans and the appearance of negative P-E anomalies might have implications for the Pliocene thermohaline circulation. The hydrological cycle intensified over the continents, where annual evaporation, rainfall, and soil moisture all increased. However, simulated summer drought conditions are not corroborated by terrestrial records, pointing to deficiencies in either the model, the boundary conditions, or the terrestrial data interpretations. The Pliocene SST pattern implicates increased ocean heat flux as a component force behind the middle Pliocene warmth, since levels of CO2, large enough to cause the extreme high latitude temperatures, would generate more tropical warming than is indicated by floral and faunal records. Surface energy fluxes, calculated by the GCM, indicate that an increased meridional ocean heat nux of 32% could reproduce the data-derived SST distribution, despite weakened atmospheric transports. The decreased wind stress values suggest that any increase of ocean heat transports would probably have resulted from a strengthening of the thermohaline circulation. C1 US GEOL SURVEY,DENVER,CO 80225. NASA,GODDARD SPACE FLIGHT CTR,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP CHANDLER, M (reprint author), COLUMBIA UNIV,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 49 TC 90 Z9 95 U1 12 U2 40 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD DEC PY 1994 VL 9 IS 3-4 BP 197 EP 219 DI 10.1016/0921-8181(94)90016-7 PG 23 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA PZ127 UT WOS:A1994PZ12700003 ER PT J AU COVEY, C THOMPSON, SL WEISSMAN, PR MACCRACKEN, MC AF COVEY, C THOMPSON, SL WEISSMAN, PR MACCRACKEN, MC TI GLOBAL CLIMATIC EFFECTS OF ATMOSPHERIC DUST FROM AN ASTEROID OR COMET IMPACT ON EARTH SO GLOBAL AND PLANETARY CHANGE LA English DT Article ID CRETACEOUS-TERTIARY BOUNDARY; GENERAL-CIRCULATION MODEL; SMOKE INJECTIONS; NUCLEAR WINTER; SENSITIVITY; EXTINCTIONS; WAR AB Impacts of comets and small (similar to 10 km) asteroids with Earth-frequent events over geologic time-would generate atmospheric dust in amounts orders of magnitude greater than historically large volcanic explosions. Three-dimensional atmospheric model simulations show that climatic effects of such impacts would include drastic cooling of land surfaces due to interception of sunlight by high-altitude dust. Unlike earlier one-dimensional calculations, the three-dimensional results indicate that large areas of the planet would escape freezing. They also suggest catastrophic changes in the hydrological cycle. C1 NATL CTR ATMOSPHER RES,BOULDER,CO 80307. CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91125. RP COVEY, C (reprint author), LAWRENCE LIVERMORE NATL LAB,DIV GLOBAL CLIMATE RES,MAIL CODE L-264,LIVERMORE,CA 94551, USA. NR 35 TC 44 Z9 44 U1 2 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD DEC PY 1994 VL 9 IS 3-4 BP 263 EP 273 DI 10.1016/0921-8181(94)90020-5 PG 11 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA PZ127 UT WOS:A1994PZ12700007 ER PT J AU MATTHEWS, E AF MATTHEWS, E TI NITROGENOUS FERTILIZERS - GLOBAL DISTRIBUTION OF CONSUMPTION AND ASSOCIATED EMISSIONS OF NITROUS-OXIDE AND AMMONIA SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID FIELD-MEASUREMENTS; SOILS; N2O; ATMOSPHERE; FOREST; EUROPE; MODEL; NITRIFICATION; VARIABILITY; GROUNDWATER AB The global distribution of nitrogen input via application of chemical nitrogenous fertilizers to agricultural ecosystems is presented. The suite of 1 degrees (latitude/longitude) resolution data bases includes primary data on fertilizer consumption, as well as supporting data sets defining the distribution and intensity of agriculture associated with fertilizer use. The data were developed from a variety of sources and reflect conditions for the mid-1980s. East Asia, where fertilizer use is increasing at similar to 10%/year, accounted for similar to 37% of the total, while North America and western Europe, where fertilizer use is leveling off, accounted for 17% and 14% of global use, respectively. Former centrally planned economies of Europe consumed one fifth of the 1984 total, but rapid increases in the 1980s are slowing, and consumption trends are variable. The most widely used chemical nitrogenous fertilizer is urea which accounted for 40% of the world's total in the mid-1980s. While almost every country consumes urea, similar to 75% of the large East Asian fertilizer use is supplied by this one fertilizer. Ammonium nitrate, used primarily in the former centrally planned economies of Europe, in West Asia, and in Africa, accounted for about one quarter of global consumption. These data were used to estimate distributions of the annual emission of nitrous oxide (N2O) and of ammonia (NH3) associated with the use of fertilizers. Applying published ranges of emission coefficients for fertilizer types in the data base yields a median emission of 0.1 Tg N2O-N, with lower and upper values of 0.03 and 2.0 Tg N2O-N in 1984. This equals <1% to similar to 3% of the total nitrogen applied via commercial fertilizers and represents <1% to 15% of the annual emission of N2O from terrestrial sources. Assuming that the similar to 4% annual increase in consumption of nitrogenous fertilizers during the 1980s corresponds to a similar to 4% rise in the release of N2O-N, yearly increases in emissions from fertilizer use are <0.01 to 0.08 Tg N2O-N equal to <1% to 3% of the current growth of atmospheric nitrous oxide. However, since no measurements of fertilizer-derived nitrous oxide emissions are available for agricultural environments in the tropics/subtropics, where similar to 40% of fertilizer N is consumed and where consumption is increasing rapidly, relative contributions of climatic regions to current and future emissions remain uncertain. Ammonia emission coefficients for simple groups of fertilizer types were applied to derive the global distribution of ammonia volatilization associated with nitrogenous fertilizer consumption. The 1984 total of similar to 5-7 Tg NH3-N, about 10-15% of the annual ammonia source, is concentrated overwhelmingly in subtropical Asia owing to the dominant use of urea with high rates of volatilization. However, the paucity of measurements in representative ecological and management environments suggests that the magnitude and distribution of current and future ammonia emission from fertilizers is still poorly known. RP MATTHEWS, E (reprint author), HUGHES STX CORP,NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 98 TC 96 Z9 107 U1 4 U2 34 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD DEC PY 1994 VL 8 IS 4 BP 411 EP 439 DI 10.1029/94GB01906 PG 29 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA PU118 UT WOS:A1994PU11800003 ER PT J AU CASNER, SM AF CASNER, SM TI UNDERSTANDING THE DETERMINANTS OF PROBLEM-SOLVING BEHAVIOR IN A COMPLEX ENVIRONMENT SO HUMAN FACTORS LA English DT Article AB It is often argued that problem-solving behavior in a complex environment is determined as much by the features of the environment as by the goals of the problem solver. This article explores a technique to determine the extent to which measured features of a complex environment influence problem-solving behavior observed within that environment. In this study, the technique is used to determine how a complex flight deck and air traffic control environment influences the strategies used by airline pilots when controlling the flight path of a modern jetliner. Data collected aboard 16 commercial flights are used to measure selected features of the task environment. A record of pilots' problem-solving behavior is analyzed to determine to what extent behavior is adapted to the environmental features that were measured. The results suggest that the measured features of the environment account for as much as half of the variability in pilots' problem-solving behavior and provide estimates on the probable effects of each environmental feature. RP CASNER, SM (reprint author), NASA,AMES RES CTR,MAIL STOP 262-4,MOFFETT FIELD,CA 94035, USA. NR 13 TC 12 Z9 12 U1 0 U2 1 PU HUMAN FACTORS SOC PI SANTA MONICA PA BOX 1369, SANTA MONICA, CA 90406 SN 0018-7208 J9 HUM FACTORS JI Hum. Factors PD DEC PY 1994 VL 36 IS 4 BP 580 EP 596 PG 17 WC Behavioral Sciences; Engineering, Industrial; Ergonomics; Psychology, Applied; Psychology SC Behavioral Sciences; Engineering; Psychology GA QG371 UT WOS:A1994QG37100001 ER PT J AU CASSEN, P AF CASSEN, P TI UTILITARIAN MODELS OF THE SOLAR NEBULA SO ICARUS LA English DT Review ID YOUNG STELLAR OBJECTS; ACCRETION DISK MODELS; T-TAURI STARS; ECCENTRIC GRAVITATIONAL INSTABILITIES; FU-ORIONIS OBJECTS; X-RAY SOURCES; PROTOSTELLAR DISKS; REFRACTORY INCLUSIONS; CIRCUMSTELLAR DISKS; INFRARED-SPECTRA AB Models of the primitive solar nebula based on a combination of theory, observations of T Tauri stars, and global conservation laws are presented. The models describe the motions of nebular gas, mixing of interstellar material during the formation of the nebula, and evolution of thermal structure in terms of several characteristic parameters. The parameters describe key aspects of the protosolar cloud (its rotation rate and collapse rate) and the nebula (its mass relative to the Sun, decay time, and density distribution). For most applications, the models are heuristic rather than predictive. Their purpose is to provide a realistic context for the interpretation of solar system data, and to distinguish those nebula characteristics that can be specified with confidence independently of the assumptions of particular models, from those that are poorly constrained. It is demonstrated that nebular gas typically experienced large radial excursions during the evolution of the nebula and that both inward and outward mean radial velocities on the order of meters per second occurred in the terrestrial planet region, with inward velocities predominant for most of the evolution. However, the time history of disk size, surface density, and radial velocities are sensitive to the total angular momentum of the protosolar cloud, which cannot be constrained by purely theoretical considerations. It is shown that a certain amount of ''formational'' mixing of interstellar material was an inevitable consequence of nebular mass and angular momentum transport during protostellar collapse, regardless of the specific transport mechanisms involved. Even if the protosolar cloud was initially homogeneous, this mixing was important because it had the effect of mingling presolar material that had experienced different degrees of thermal processing during collapse and passage through the accretion shock. Nebular thermal structure is less sensitive to poorly constrained parameters than is dynamical history. A simple criterion is derived for the condition that silicate grains are evaporated at midplane, and it is argued that this condition was probably fulfilled early in nebular history. Cooling of a hot nebula due to coagulation of dust and consequent local reduction of optical depth is examined, and it is shown how such a process leads naturally to an enrichment of rock-forming elements in the gas phase. (C) 1994 Academic Press, Inc. RP CASSEN, P (reprint author), NASA,AMES RES CTR,THEORET STUDIES BRANCH,MOFFETT FIELD,CA 94035, USA. NR 101 TC 92 Z9 92 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 1994 VL 112 IS 2 BP 405 EP 429 DI 10.1006/icar.1994.1195 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QF366 UT WOS:A1994QF36600013 ER PT J AU HANNER, MS HACKWELL, JA RUSSELL, RW LYNCH, DK AF HANNER, MS HACKWELL, JA RUSSELL, RW LYNCH, DK TI SILICATE EMISSION FEATURE IN THE SPECTRUM OF COMET MUELLER 1993A SO ICARUS LA English DT Article ID INTERPLANETARY DUST PARTICLES; INTERSTELLAR EXTINCTION; SOLAR NEBULA; OLIVINE; SPECTROPHOTOMETRY; SPECTROSCOPY; PYROXENE; AIRBORNE; MICRONS; GROWTH AB An 8- to 13-mu m spectrum of comet Mueller 1993a, a dynamically new comet, was acquired when the comet was at R = 2 AU. Strong, structured silicate emission is present, closely resembling that seen in Comet P/Halley at smaller R. For the first time in a new comet, the 11.2-mu m peak of crystalline olivine was detected, demonstrating that crystalline olivine particles were widespread in the solar nebula. Crystalline olivine particles could have formed in the inner protosolar nebula at temperatures greater than 1200 K; extensive radial mixing would have been required to transport these grains to the region of comet formation. Either there was more radial mixing in the solar nebula than some current theories predict or the olivine grains have a presolar origin. (C) 1994 Academic Press, Inc. C1 AEROSP CORP,LOS ANGELES,CA 90009. RP HANNER, MS (reprint author), CALTECH,JET PROP LAB,MS 183-601,PASADENA,CA 91109, USA. NR 48 TC 63 Z9 64 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 1994 VL 112 IS 2 BP 490 EP 495 DI 10.1006/icar.1994.1200 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QF366 UT WOS:A1994QF36600018 ER PT J AU ROETTGER, EE BURATTI, BJ AF ROETTGER, EE BURATTI, BJ TI ULTRAVIOLET-SPECTRA AND GEOMETRIC ALBEDOS OF 45 ASTEROIDS SO ICARUS LA English DT Article ID IUE OBSERVATIONS; VESTA; NM AB Spectral reflectances and geometric albedos between 2300 and 3250 Angstrom are determined for 45 asteroids from data acquired by the International Ultraviolet Explorer satellite. The geometric albedos are consistently low, ranging from similar to 0.002 for C-type asteroids to similar to 0.08 for M-type asteroids. An exception is the single E-type asteroid (33 Nysa) with a geometric albedo of 0.3 at 2950 Angstrom. We find that the three major asteroid taxonomic classes persist into the UV. The taxonomic classes are distinguished primarily by their albedos, but S types are generally redder than C or M types. The first ultraviolet phase curves of asteroids are presented. (C) 1994 Academic Press, Inc. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 27 TC 15 Z9 16 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 1994 VL 112 IS 2 BP 496 EP 512 DI 10.1006/icar.1994.1201 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QF366 UT WOS:A1994QF36600019 ER PT J AU TRYKA, KA BROWN, RH CRUIKSHANK, DP OWEN, TC GEBALLE, TR DEBERGH, C AF TRYKA, KA BROWN, RH CRUIKSHANK, DP OWEN, TC GEBALLE, TR DEBERGH, C TI TEMPERATURE OF NITROGEN ICE ON PLUTO AND ITS IMPLICATIONS FOR FLUX MEASUREMENTS SO ICARUS LA English DT Article ID REFLECTANCE SPECTROSCOPY; WAVELENGTH DEPENDENCE; CHARON; SURFACE; TRITON; ATMOSPHERE; SYSTEM; SPECTRA; MODELS AB Previous work by K. A. Tryka et al. (Science 261, 751-754, 1993) has shown that the profile of the 2.148-mu m band of solid nitrogen can be used as a ''thermometer'' and determined the temperature of nitrogen ice on Triton to be 38(-1)(+2) K. Here we reevaluate that data and refine the temperature value to 38 +/- 1 K. Applying the same technique to Pluto we determine that the temperature of the N-2 ice on that body is 40 +/- 2 K. Using this result we have created a nonisothermal flux model of the Pluto-Charon system, The model treats Pluto as a body with symmetric N-2 polar caps and an equatorial region devoid of N-2. Comparison with the infrared and millimeter flux measurements shows that the published fluxes are consistent with models incorporating extensive N-2 polar caps (down to +/-15 degrees or 20 degrees latitude) and an equatorial region with a bolometric albedo less than or equal to 0.2. (C) 1994 Academic Press, Inc. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. JOINT ASTRON CTR,HILO,HI 96720. OBSERV PARIS,F-92195 MEUDON,FRANCE. RP TRYKA, KA (reprint author), CALTECH,DIV GEOL & PLANETARY SCI,MS 170-25,PASADENA,CA 91125, USA. OI Tryka, Kimberly/0000-0002-5399-4235 NR 42 TC 66 Z9 66 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 1994 VL 112 IS 2 BP 513 EP 527 DI 10.1006/icar.1994.1202 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QF366 UT WOS:A1994QF36600020 PM 11538596 ER PT J AU ZENT, AP QUINN, RC JAKOSKY, BM AF ZENT, AP QUINN, RC JAKOSKY, BM TI FRACTIONATION OF NITROGEN ISOTOPES ON MARS - THE ROLE OF THE REGOLITH AS A BUFFER SO ICARUS LA English DT Note ID ATMOSPHERE; CLIMATE; ESCAPE AB We have measured the adsorption of molecular nitrogen (N-2) on palagonite, and molded the adsorbed nitrogen inventory on the martian regolith. We were motivated by the fact that models of isotopic evolution predict stronger N-2 fractionation than reported by Viking. Possible scenarios for reconciling models with the observation include a heavy CO2 atmosphere early in the planet's history, continued outgassing of N-2 throughout the history of Mars, or a substantial adsorbed inventory. In this paper we investigate the plausibility of the last explanation. We find that the regolith reservoir of adsorbed N-2 is inadequate by itself to buffer the atmospheric isotopic composition, but may play a role depending on the total regolith surface area available. (C) 1994 Academic Press, Inc. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. UNIV COLORADO,DEPT GEOL SCI,BOULDER,CO 80309. RP ZENT, AP (reprint author), NASA,AMES RES CTR,SETI INST,MOFFETT FIELD,CA 94035, USA. NR 20 TC 9 Z9 9 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 1994 VL 112 IS 2 BP 537 EP 540 DI 10.1006/icar.1994.1205 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QF366 UT WOS:A1994QF36600023 ER PT J AU HUCKINS, E AHLF, P AF HUCKINS, E AHLF, P TI SPACE STATION POWER REQUIREMENTS AND ISSUES SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB This paper provides an overview of the space station configuration and summarizes the requirements, architecture, and significant challenges associated with the Electrical Power System (EPS). The space station configuration was baselined during the Systems Design Review (SDR) process in March, 1994. The current configuration includes the addition of Russia as an international partner, resulting in major changes to the assembly sequence, pressurized module complement, and overall power architecture. The Russian contributions to the power system architecture, as well as an overview and development status of the US provided elements is presented. Finally, a planned flight demonstration of solar dynamic power system on the Mir as part of the first phase of US/Russian cooperation in human space flight is described. RP HUCKINS, E (reprint author), NASA HEADQUARTERS,OFF SPACE FLIGHT,300 E ST SW,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 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 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD DEC PY 1994 VL 9 IS 12 BP 3 EP 7 DI 10.1109/62.334751 PG 5 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA PV190 UT WOS:A1994PV19000003 ER PT J AU YAO, XS MALEKI, L AF YAO, XS MALEKI, L TI A NOVEL 2-D PROGRAMMABLE PHOTONIC TIME-DELAY DEVICE FOR MILLIMETER-WAVE SIGNAL-PROCESSING APPLICATIONS SO IEEE PHOTONICS TECHNOLOGY LETTERS LA English DT Article ID PHASED-ARRAY ANTENNAS; OPTICAL ARCHITECTURE; LINE AB We describe a novel programmable photonic true time-delay device that has the properties of low loss, inherent two dimensionality with a packing density exceeding 25 lines/cm(2), virtually infinite bandwidth, and is easy to manufacture. The delay resolution of the device is on the order of femtoseconds (microns in space) and the total delay exceeds one nanosecond (30 cm in space), RP YAO, XS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 16 TC 26 Z9 26 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 1041-1135 J9 IEEE PHOTONIC TECH L JI IEEE Photonics Technol. Lett. PD DEC PY 1994 VL 6 IS 12 BP 1463 EP 1465 DI 10.1109/68.392210 PG 3 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA QB709 UT WOS:A1994QB70900023 ER PT J AU WU, TK AF WU, TK TI 4-BAND FREQUENCY-SELECTIVE SURFACE WITH DOUBLE-SQUARE-LOOP PATCH ELEMENTS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note ID EQUIVALENT-CIRCUIT; GRIDS AB Design and experimental verifications are presented for a Sour-band frequency selective surface (FSS) with perfectly conducting double-square-loop (DSL) patch elements. A single screen DSL element FSS is demonstrated for 1) a four-band FSS which reflects the X- and Ka-band signals while passing the S- and Ku-band signals, and 2) a low pass (or Ka-add on) FSS that reflects the Ka-band signal while passing the S-, X-, and Ku-band signals. Cascading the above low-pass FSS with a previously published single screen tri-bsnd FSS, a double screen FSS is also successfully demonstrated for the Cassini four-band application. The good agreement obtained between the measured and the computed results verified both the single and double screen four-frequency FSS approaches for the Cassini Project. RP WU, TK (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 20 TC 76 Z9 79 U1 1 U2 10 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 DEC PY 1994 VL 42 IS 12 BP 1659 EP 1663 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA QD417 UT WOS:A1994QD41700012 ER PT J AU JAIN, RK FLOOD, DJ AF JAIN, RK FLOOD, DJ TI SIMULATION OF HIGH-EFFICIENCY N(+)P INDIUM-PHOSPHIDE SOLAR-CELL RESULTS AND FUTURE IMPROVEMENTS SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Note AB A simulation of the highest efficiency (19.1% AMO) n(+)p indium phosphide (InP) solar cell was made using a computer code PC-1D in order to understand it and suggest future improvements to it. Available cell design and process data aas used in the simulation. Minority carrier diffusion lengths in the emitter and base have been varied to match the experimental cell I-V characteristics with the calculated results. To further understand and improve the InP cell efficiency, simulations were performed using improved values of cell material and process parameters. We show that the efficiency of this cell could be increased to more than 23% AMO by incorporating the suggested cell material, design and process improvements. At these high efficiencies InP cell technology will be very attractive for space use. RP JAIN, RK (reprint author), NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 10 TC 9 Z9 9 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9383 EI 1557-9646 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD DEC PY 1994 VL 41 IS 12 BP 2473 EP 2475 DI 10.1109/16.337476 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA PW501 UT WOS:A1994PW50100036 ER PT J AU CHENG, HJ WHITAKER, JF WELLER, TM KATEHI, LPB AF CHENG, HJ WHITAKER, JF WELLER, TM KATEHI, LPB TI TERAHERTZ-BANDWIDTH CHARACTERISTICS OF COPLANAR TRANSMISSION-LINES ON LOW PERMITTIVITY SUBSTRATES SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article; Proceedings Paper CT 1994 International Microwave Symposium (IMS) and Microwave and Millimeter-Wave Circuits Symposium (MMWMCS) CY MAY 23-27, 1994 CL SAN DIEGO, CA SP IEEE ID OPTOELECTRONICS; DISPERSION AB Coplanar striplines and waveguides capable of supporting ultra-high-frequency pulses over many millimeters of propagation length have been fabricated on low-permittivity substrates, including a durable 1,4-mu m-thick membrane. These transmission lines were characterized using broadband pulses from a novel in situ optoelectronic test-signal generator together. with an electro-optic probe tip and an optically-based sampling technique. Pulse-propagation characteristics for the coplanar lines on the low-permittivity substrates have been compared in both the time and frequency domains with the transmission behavior of lines on GaAs Substrates. A semi-empirical model has also been used to simulate the experimental results with good agreement, helping to indicate the origin of the distortion mechanisms involved. In addition, for the coplanar waveguide structures, waveforms corresponding to the even and odd modes have been individually resolved in the time domain for lines fabricated on the GaAs and membrane substrates. C1 UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109. RP CHENG, HJ (reprint author), UNIV MICHIGAN,CTR ULTRAFAST OPT SCI,ANN ARBOR,MI 48109, USA. NR 22 TC 38 Z9 38 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD DEC PY 1994 VL 42 IS 12 BP 2399 EP 2406 DI 10.1109/22.339773 PN 2 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA QA305 UT WOS:A1994QA30500011 ER PT J AU ZIRATH, HHG CHI, CY RORSMAN, N REBEIZ, GM AF ZIRATH, HHG CHI, CY RORSMAN, N REBEIZ, GM TI A 40-GHZ INTEGRATED QUASI-OPTICAL SLOT HFET MIXER SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article; Proceedings Paper CT 1994 International Microwave Symposium (IMS) and Microwave and Millimeter-Wave Circuits Symposium (MMWMCS) CY MAY 23-27, 1994 CL SAN DIEGO, CA SP IEEE AB We present for the first time a quasi-optical mixer realized as a resistive HFET mixer with an integrated slot antenna. Two different types of HFET's, based on GaAs and InP, are compared for this application. The mixer conversion loss, defined as the measured IF power in the 50 Omega load divided by the RF power available at the slot-antenna terminals, is better than 7 dB at LO powers down to 0 dBm. Subharmonic pumping of the mixer is also investigated. This topology has a potential interest for future low-cost millimeter-wave receivers for automobile radar and speed detector systems. C1 UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109. NATL DEF RES ESTAB,DEPT INFORMAT TECHNOL,UMEA,SWEDEN. RP ZIRATH, HHG (reprint author), CHALMERS UNIV TECHNOL,DEPT MICROWAVE TECHNOL,S-41296 GOTHENBURG,SWEDEN. RI Rorsman, Niklas/C-2655-2009 OI Rorsman, Niklas/0000-0001-9916-7633 NR 9 TC 14 Z9 14 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD DEC PY 1994 VL 42 IS 12 BP 2492 EP 2497 DI 10.1109/22.339787 PN 2 PG 6 WC Engineering, Electrical & Electronic SC Engineering GA QA305 UT WOS:A1994QA30500025 ER PT J AU OLDMAN, TR FLEETWOOD, DM CHEEK, T MASSENGILL, L VANVONNO, N SHANEYFELT, MR EISEN, H BOESCH, HE SCHRIMPF, RD CAMPBELL, A BENDEKOVIC, J EMILY, D GRAWET, S MARSHALL, P BUCHNER, S GASIOT, J COSS, J KRULL, W FARREN, J FREDERICKSON, R LELIS, A AMRAM, A LENAHAN, P AF OLDMAN, TR FLEETWOOD, DM CHEEK, T MASSENGILL, L VANVONNO, N SHANEYFELT, MR EISEN, H BOESCH, HE SCHRIMPF, RD CAMPBELL, A BENDEKOVIC, J EMILY, D GRAWET, S MARSHALL, P BUCHNER, S GASIOT, J COSS, J KRULL, W FARREN, J FREDERICKSON, R LELIS, A AMRAM, A LENAHAN, P TI SUMMARY OF THE 1994 IEEE INTERNATIONAL NUCLEAR AND SPACE RADIATION EFFECTS CONFERENCE SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Editorial Material C1 SANDIA NATL LABS,LIVERMORE,CA 94550. TEXAS INSTRUMENTS INC,DALLAS,TX 75265. VANDERBILT UNIV,NASHVILLE,TN 37240. HARRIS SEMICOND INC,MELBOURNE,FL 32901. UNIV ARIZONA,TUCSON,AZ 85721. USN,RES LAB,WASHINGTON,DC 20375. UNIV MONTPELLIER 2,F-34095 MONTPELLIER,FRANCE. JET PROPULS LAB,PASADENA,CA. IBIS TECHNOL CORP,DANVERS,MA. UKAEA,HARWELL INSTRUMENTS,HARWELL,BERKS,ENGLAND. AEROSP CORP,LOS ANGELES,CA 90009. PENN STATE UNIV,UNIVERSITY PK,PA 16802. RP OLDMAN, TR (reprint author), USA,RES LAB,WASHINGTON,DC, USA. RI Schrimpf, Ronald/L-5549-2013 OI Schrimpf, Ronald/0000-0001-7419-2701 NR 0 TC 0 Z9 0 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 DEC PY 1994 VL 41 IS 6 BP 1804 EP 1807 PN 1 PG 4 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700001 ER PT J AU GUTIERREZ, RC SWIFT, GM DUBOVITSKY, S BARTMAN, RK BARNES, CE DORSKY, L AF GUTIERREZ, RC SWIFT, GM DUBOVITSKY, S BARTMAN, RK BARNES, CE DORSKY, L TI RADIATION EFFECTS ON FUSED BICONICAL TAPER WAVELENGTH-DIVISION MULTIPLEXERS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE ID REFRACTIVE-INDEX; COUPLERS; DEPENDENCE; FIBERS AB The effects of radiation on fused biconical taper wavelength division multiplexers are presented. A theoretical model indicates that index changes in the fiber are primarily responsible for the degradation of these devices. RP GUTIERREZ, RC (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 24 TC 6 Z9 6 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 EI 1558-1578 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 1950 EP 1957 DI 10.1109/23.340529 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700019 ER PT J AU MARSHALL, PW DALE, CJ CARTS, MA LABEL, KA AF MARSHALL, PW DALE, CJ CARTS, MA LABEL, KA TI PARTICLE-INDUCED BIT ERRORS IN HIGH-PERFORMANCE FIBER OPTIC DATA LINKS FOR SATELLITE DATA MANAGEMENT SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE AB Experimental test methods and analysis tools are demonstrated to assess particle-induced bit errors on fiber optic link receivers for satellites. Susceptibility to direct ionization from low LET particles is quantified by analyzing proton and helium ion data as a function of particle LET. Existing single event analysis approaches are shown to apply, with appropriate modifications, to the regime of temporally (rather than spatially) distributed bits, even though the sensitivity to single events exceeds conventional memory technologies by orders of magnitude. The cross-section LET dependence follows a Weibull distribution at data rates from 200 to 1000 Mbps and at various incident optical power levels. The LET threshold for errors is shown, through both experiment and modeling, to be 0 in all cases! The error cross-section exhibits a strong inverse dependence on received optical power in the LET range where most orbital single events would occur, thus indicating that errors can be minimized by operating links with higher incident optical power. Also, an analytic model is described which incorporates the appropriate physical characteristics of the link as well as the optical and receiver electrical characteristics. Results indicate appropriate steps to assure suitable link performance even in severe particle orbits. C1 SFA INC,LANDOVER,MD 20785. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP MARSHALL, PW (reprint author), USN,RES LAB,WASHINGTON,DC 20375, USA. NR 10 TC 71 Z9 76 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 1958 EP 1965 DI 10.1109/23.340530 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700020 ER PT J AU LABEL, KA HAWKINS, DK COOLEY, JA SEIDLECK, CM MARSHALL, P DALE, C GATES, MM KIM, HS STASSINOPOULOS, EG AF LABEL, KA HAWKINS, DK COOLEY, JA SEIDLECK, CM MARSHALL, P DALE, C GATES, MM KIM, HS STASSINOPOULOS, EG TI SINGLE EVENT EFFECT GROUND TEST-RESULTS FOR A FIBER OPTIC DATA INTERCONNECT AND ASSOCIATED ELECTRONICS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE AB As spacecraft unlock the potential of fiber optics for spaceflight applications, system level bit error rates become of concern to the system designer. We present ground test data and analysis on candidate system components. C1 NRL,SFA,WASHINGTON,DC. NASA,GODDARD SPACE FLIGHT CTR,JACKSON & TULL,GREENBELT,MD 20771. RP LABEL, KA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES ST SYST CORP,CODE 7351,GREENBELT,MD 20771, USA. NR 11 TC 7 Z9 7 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 1999 EP 2004 DI 10.1109/23.340535 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700025 ER PT J AU SWIFT, GM PADGETT, DJ JOHNSTON, AH AF SWIFT, GM PADGETT, DJ JOHNSTON, AH TI A NEW CLASS OF SINGLE EVENT HARD ERRORS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE ID HEAVY AB Experimental results reported here indicate that heavy ions can cause hard errors in conventional one-transistor dynamic memory cells in addition to, as previously reported, four-transistor static cells. Analysis of this data reveals that the hard errors fall into two classes, one that is consistent with the expected single-ion dose mechanism and another that is clearly inconsistent. In particular, the new class of hard errors is separable from the dosed cells based on irradiation conditions and the data-loss time scale and direction. Further, this damage is not additive between ion hits, does not follow ''effective'' LET, and is quite resistant to annealing. As a result, these hard errors would accumulate over long missions and, assuming the damaged element is the access transistor, can be expected in other types of storage elements with similar transistors, e.g., static RAMs and microprocessor registers. Additionally, it was found that scaling increases the susceptibility for a given ion and lowers the ion threshold, although lowered bias mitigates the damage. RP SWIFT, GM (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 30 Z9 30 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2043 EP 2048 DI 10.1109/23.340540 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700030 ER PT J AU ROTH, DR MCNULTY, PJ BEAUVAIS, WJ REED, RA STASSINOPOULOS, EG AF ROTH, DR MCNULTY, PJ BEAUVAIS, WJ REED, RA STASSINOPOULOS, EG TI SOLID-STATE MICRODOSIMETER FOR RADIATION MONITORING IN SPACECRAFT AND AVIONICS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE ID DOSIMETERS AB An instrument is described which is designed to characterize the complex radiation, environments inside spacecraft and airplanes in terms of the risk of SEEs in the present and planned microelectronic systems and in terms of the risk to flight crews and passengers. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP ROTH, DR (reprint author), CLEMSON UNIV,DEPT PHYS & ASTRON,CLEMSON,SC 29634, USA. NR 12 TC 16 Z9 16 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2118 EP 2124 DI 10.1109/23.340551 PN 1 PG 7 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700041 ER PT J AU KATZ, R BARTO, R MCKERRACHER, P KOGA, R AF KATZ, R BARTO, R MCKERRACHER, P KOGA, R TI SEU HARDENING OF FIELD-PROGRAMMABLE GATE ARRAYS (FPGAS) FOR SPACE APPLICATIONS AND DEVICE CHARACTERIZATION SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE AB Field Programmable Gate Arrays (FPGAs) are being used in space applications because of attractive attributes: good density, moderate speed, low cost, and quick turn-around time. However, these devices are susceptible to Single Event Upsets (SEUs). An approach using triple modular redundancy (TMR) and feedback was developed for flip-flop hardening in these devices. Test data showed excellent results for this circuit topology. Total dose and Single Event Effect (SEE) testing have been performed on recently released technologies. Failures are analyzed and test methodology is discussed. C1 INTELSAT,PALO ALTO,CA 94303. JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723. AEROSP CORP,EL SEGUNDO,CA 90245. RP KATZ, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 6 TC 20 Z9 21 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2179 EP 2186 DI 10.1109/23.340560 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700050 ER PT J AU CALVEL, P LAMOTHE, P BARILLOT, C ECOFFET, R DUZELLIER, S STASSINOPOULOS, EG AF CALVEL, P LAMOTHE, P BARILLOT, C ECOFFET, R DUZELLIER, S STASSINOPOULOS, EG TI SPACE RADIATION EVALUATION OF 16-MBIT DRAMS FOR MASS MEMORY APPLICATIONS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE AB This paper presents heavy ions, protons and total dose data results for 16 Mbit DRAMs from IBM and TEXAS INSTRUMENTS, including a 'built-in ECC' DRAM. Single Event Phenomena rate are calculated for low earth orbits. C1 CNES,F-31035 TOULOUSE,FRANCE. CERT,DERTS,F-31035 TOULOUSE,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP CALVEL, P (reprint author), ALCATEL ESPACE,26 AV JF CHAMPOLL,BP 1187,F-31037 TOULOUSE,FRANCE. NR 7 TC 24 Z9 24 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2267 EP 2271 DI 10.1109/23.340574 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700063 ER PT J AU VAMPOLA, AL LAURIENTE, M WILKINSON, DC ALLEN, J ALBIN, F AF VAMPOLA, AL LAURIENTE, M WILKINSON, DC ALLEN, J ALBIN, F TI SINGLE EVENT UPSETS CORRELATED WITH ENVIRONMENT SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE AB Single Event Upset rates on satellites in different Earth orbits are correlated with solar protons and geomagnetic activity and also with the NASA AP8 proton model to extract information about satellite anomalies caused by the space environment. An extensive discussion of the SEU data base from the TOMS solid state recorder and an algorithm for correcting spontaneous upsets in it are included as an Appendix, SAMPEX and TOMS, which have the same memory chips, have similar normalized responses in the South Atlantic Anomaly, SEU rates due to solar protons over the polar caps are within expectations. No geomagnetic activity effects can be discerned in the SEU rates. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NATL GEOPHYS DATA CTR,BOULDER,CO 80303. RP VAMPOLA, AL (reprint author), UNIV GREENBELT,RES FDN,6411 IVY LANE,GREENBELT,MD 20770, USA. NR 7 TC 9 Z9 9 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2383 EP 2388 DI 10.1109/23.340591 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700080 ER PT J AU REED, RA MCNULTY, PJ BEAUVAIS, WJ ABDELKADER, WG STASSINOPOULOS, EG BARTH, JCL AF REED, RA MCNULTY, PJ BEAUVAIS, WJ ABDELKADER, WG STASSINOPOULOS, EG BARTH, JCL TI A SIMPLE ALGORITHM FOR PREDICTING PROTON SEU RATES IN-SPACE COMPARED TO THE RATES MEASURED ON THE CRRES SATELLITE SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE AB A new simulation code, the Clemson Onmidirectional Spallation Model for Interaction in Circuits (COSMIC), is described and its predictions agree with SEU data from four devices flown as part of the microelectronics package experiment on the CRRES satellite. The code uses CUPID for determining the energy depositions in the sensitive volumes; it allows proton exposures with arbitrary angles of incidence including random omnidirectional exposure; and the user specifies the thickness of shielding on six sides of the sensitive volume. COSMlC is used as part of an algorithm developed to predict the rate proton induced single event upsets occur in the space radiation environment given by AP-8. In testing the algorithm, the position coordinates are taken from the satellite's ephemeris data, but calculations based on position coordinates from orbital codes were also in agreement with the measured values. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP REED, RA (reprint author), CLEMSON UNIV,DEPT PHYS & ASTRON,CLEMSON,SC 29634, USA. NR 13 TC 34 Z9 35 U1 1 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2389 EP 2395 DI 10.1109/23.340592 PN 1 PG 7 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700081 ER PT J AU BUEHLER, MG SOLI, GA BLAES, BR RATLIFF, JM GARRETT, HB AF BUEHLER, MG SOLI, GA BLAES, BR RATLIFF, JM GARRETT, HB TI CLEMENTINE RRELAX SRAM PARTICLE SPECTROMETER SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE ID SOLAR AB The Clementine RRELAX radiation monitor chip consists of a p-FET total dose monitor and a 4-kbit SRAM particle spectrometer. Eight of these chips were included in the RRELAX and used to detect the passage of the Clementine (S/C) and the innerstage adapter (ISA) through the earth's radiation belts and the 21-Feb 1994 solar flare. This is the first space flight for this 1.2-mu m rad-soft custom CMOS radiation monitor. This paper emphasizes results from the SRAM particle detector which showed that it (a) has a detection range of five orders of magnitude relative to the 21-Feb solar flare; (b) is not affected by electrons, and (c) detected microflares occurring with a 26.5-day period. RP BUEHLER, MG (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 11 TC 2 Z9 3 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2404 EP 2411 DI 10.1109/23.340595 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700084 ER PT J AU JOHNSTON, AH SWIFT, GM RAX, BG AF JOHNSTON, AH SWIFT, GM RAX, BG TI TOTAL-DOSE EFFECTS IN CONVENTIONAL BIPOLAR-TRANSISTORS AND LINEAR INTEGRATED-CIRCUITS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE ID RADIATION; DEVICES AB Total dose damage is investigated for discrete bipolar transistors and linear integrated circuits that are fabricated with older processing technologies, but are frequently used in space applications. The Kirk effect limits the current density of discrete transistors with high collector breakdown voltage, increasing their sensitivity to ionizing radiation because they must operate low injection levels. Bias conditions during irradiation had different effects on discrete and integrated circuit transistors: discrete devices were strongly dependent on bias conditions, whereas damage in the linear ICs was nearly the same with or without bias. There were also large differences in the response of these devices at low dose rates. None of the discrete transistors exhibited enhanced damage at low dose rates, whereas substantially more damage occurred in the linear devices under low dose rate conditions, particularly for parameters that rely directly on pnp transistors. The threshold for dose rate effects in pnp transistors was about 0.01 rad(Si)/s, which is approximately two orders of magnitude lower than the corresponding threshold for npn transistors in integrated circuits. RP JOHNSTON, AH (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA, USA. NR 20 TC 121 Z9 133 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2427 EP 2436 DI 10.1109/23.340598 PN 1 PG 10 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700087 ER PT J AU SHAW, DC SWIFT, GM PADGETT, DJ JOHNSTON, AH AF SHAW, DC SWIFT, GM PADGETT, DJ JOHNSTON, AH TI RADIATION EFFECTS IN 5-VOLT AND ADVANCED LOWER VOLTAGE DRAMS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE ID RANDOM-ACCESS MEMORIES; 16-MB CMOS SRAM; 256-MB DRAM; DEPENDENCE; CIRCUITS; MODEL AB This work examines the effects of ionizing radiation on highly scaled DRAMs. Several 4 Mb and 16 Mb DRAMs with 5.0, 3.6, and 3.3 volt memory arrays are compared. A novel approach using memory cell retention time is introduced and applied that allows insight into the effects of radiation on individual devices within a DRAM array. Data from this new application of retention time exhibits significant changes due to ionizing radiation, even at low levels where other device parameters do not change significantly. The parameter, tau (50%), is introduced that helps classify DRAM radiation response. Data are presented showing that there are two different damage mechanisms that affect DRAM radiation response. Finally, a relationship between threshold voltage and retention time is shown for several DRAMs. RP SHAW, DC (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 7 Z9 7 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2452 EP 2458 DI 10.1109/23.340601 PN 1 PG 7 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700090 ER PT J AU LEE, CI RAX, BG JOHNSTON, AH AF LEE, CI RAX, BG JOHNSTON, AH TI TOTAL IONIZING DOSE EFFECTS ON HIGH-RESOLUTION (12-BIT, 14-BIT) ANALOG-TO-DIGITAL CONVERTERS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1994 IEEE Annual Conference on Nuclear and Space Radiation Effects (NSREC 94) CY JUL 18-22, 1994 CL TUCSON, AZ SP IEEE ID A/D CONVERTERS AB This paper reports total dose radiation test results for high resolution 12-/14-bit A/D converters. Small changes in internal components can cause these devices to fail their specifications at relatively low total dose levels. Degradation of signal-to-noise ratio becomes increasingly important for high-accuracy converters. Rebound effects in the thick-oxide MOS devices cause these responses to be different at low and high dose rates, which is a major concern for space applications. RP LEE, CI (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 TC 6 Z9 12 U1 2 U2 2 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 DEC PY 1994 VL 41 IS 6 BP 2459 EP 2466 DI 10.1109/23.340602 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ157 UT WOS:A1994PZ15700091 ER PT J AU BRUCKER, GJ STASSINOPOULOS, EG STAUFFER, CA AF BRUCKER, GJ STASSINOPOULOS, EG STAUFFER, CA TI CORRECTED MULTIPLE UPSETS AND BIT REVERSALS FOR IMPROVED 1-S RESOLUTION MEASUREMENTS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article AB Previous work has studied the generation of single and multiple errors in control and irradiated static RAM samples (Harris 6504RH) which were exposed to heavy ions for relatively long intervals of time (minute), and read out only after the beam was shut off. The present investigation involved storing 4k X 1 bit maps every second during 1 min ion exposures at low flux rates of 10(3) ions/cm(2)-s in order to reduce the chance of two sequential ions upsetting adjacent bits. The data were analyzed for the presence of adjacent upset bit locations in the physical memory plane, which were previously defined to constitute multiple upsets. Improvement in the time resolution of these measurements has provided more accurate estimates of multiple upsets. The results indicate that the percentage of multiples decreased from a high of 17% in the previous experiment to less than 1% for this new experimental technique. Consecutive double and triple upsets (reversals of bits) were detected. These were caused by sequential ions hitting the same bit, with one or two reversals of state occurring in a 1-min run. In addition to these results, a status review for these same parts covering 3.5 years of imprint damage recovery is also presented. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. SES,GREENBELT,MD. NR 8 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 1994 VL 41 IS 6 BP 2698 EP 2705 DI 10.1109/23.340636 PN 2 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PZ160 UT WOS:A1994PZ16000004 ER PT J AU BHANU, B FAUGERAS, O SRIDHAR, B THORPE, CE AF BHANU, B FAUGERAS, O SRIDHAR, B THORPE, CE TI INTRODUCTION TO THE SPECIAL SECTION ON PERCEPTION-BASED REAL-WORLD NAVIGATION SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Editorial Material ID IMAGE FLOW C1 NATL RES INST COMP SCI & CONTROL THEORY,COMP VIS & ROBOT GRP,VALBONNE,FRANCE. ECOLE POLYTECH,F-75230 PARIS,FRANCE. NASA,AMES RES CTR,AIRCRAFT GUIDANCE & NAVIGAT BRANCH,MOFFETT FIELD,CA 94035. CARNEGIE MELLON UNIV,INST ROBOT,PITTSBURGH,PA 15213. RP BHANU, B (reprint author), UNIV CALIF RIVERSIDE,VISUALIZAT & INTELLIGENT SYST LAB,RIVERSIDE,CA 92521, USA. NR 4 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 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD DEC PY 1994 VL 10 IS 6 BP 725 EP 727 PG 3 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA PY303 UT WOS:A1994PY30300001 ER PT J AU SUORSA, RE SRIDHAR, B AF SUORSA, RE SRIDHAR, B TI A PARALLEL IMPLEMENTATION OF A MULTISENSOR FEATURE-BASED RANGE-ESTIMATION METHOD SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article ID MOTION; IMAGES AB There are many proposed vision based methods to perform obstacle detection and avoidance for autonomous or semi-autonomous vehicles. A system capable of supporting autonomous helicopter navigation will need to extract obstacle information from imagery at rates varying from ten images per second to thirty or more images per second depending on the vehicle speed. This paper describes an efficient and flexible parallel implementation of a multisensor feature based range-estimation algorithm, targeted for automated helicopter flight. The algorithm can track hundreds of features in multiple image sensors using an extended Kalman filter to estimate the feature's location in a master sensor coordinate frame. The feature-tracking algorithm has reached relative maturity in the laboratory and is now being ported to several real-time architectures to support autonomous helicopter navigation research. The focus of this paper is nob the core theory of the vision algorithm itself, but those aspects of it that affect the method of parallelization. The performance of the parallel algorithm is analyzed, with respect to three load balancing schemes, on bath a distributed-memory and shared-memory parallel computer. RP SUORSA, RE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 38 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 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD DEC PY 1994 VL 10 IS 6 BP 755 EP 768 DI 10.1109/70.338530 PG 14 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA PY303 UT WOS:A1994PY30300004 ER PT J AU MATTHIES, L GRANDJEAN, P AF MATTHIES, L GRANDJEAN, P TI STOCHASTIC PERFORMANCE MODELING AND EVALUATION OF OBSTACLE DETECTABILITY WITH IMAGING RANGE SENSORS SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Note ID STEREO AB Statistical modeling and evaluation of the performance of obstacle detection systems for Unmanned Ground Vehicles (UGV's) is essential for the design, evaluation, and comparison of sensor systems. In this report, we address this issue for imaging range sensors by dividing the evaluation problem into two levels: quality of the range data itself and quality of the obstacle detection algorithms applied to the range data. We review existing models of the quality of range data from stereo vision and AM-CW LADAR, then use these to derive a new model for the quality of a simple obstacle detection algorithm. This model predicts the probability of detecting obstacles and the probability of false alarms, as a function of the size and distance of the obstacle, the resolution of the sensor, and the level of noise in the range data. We evaluate these models experimentally using range data from stereo image pairs of a gravel road with known obstacles at several distances. The results show that the approach is a promising toot for predicting and evaluating the performance of obstacle detection with imaging range sensors. C1 CTR NATL ETUD SPATIALES,F-31055 TOULOUSE,FRANCE. RP MATTHIES, L (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 21 Z9 21 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 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD DEC PY 1994 VL 10 IS 6 BP 783 EP 792 DI 10.1109/70.338533 PG 10 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA PY303 UT WOS:A1994PY30300007 ER PT J AU YEE, HC SWEBY, PK AF YEE, HC SWEBY, PK TI GLOBAL ASYMPTOTIC-BEHAVIOR OF ITERATIVE IMPLICIT SCHEMES SO INTERNATIONAL JOURNAL OF BIFURCATION AND CHAOS LA English DT Article ID NUMERICAL-SOLUTIONS AB The global asymptotic nonlinear behavior of some standard iterative procedures in solving nonlinear systems of algebraic equations arising from four implicit linear multistep methods (LMMs) in discretizing three models of 2 x 2 systems of first-order autonomous nonlinear ordinary differential equations (ODEs) is analyzed using the theory of dynamical systems. The iterative procedures include simple iteration and full and modified Newton iterations. The results are compared with standard Runge-Kutta explicit methods, a noniterative implicit procedure, and the Newton method of solving the steady part of the ODEs. Studies showed that aside from exhibiting spurious asymptotes, all of the four implicit LMMs can change the type and stability of the steady states of the differential equations (DEs). They also exhibit a drastic distortion but less shrinkage of the basin of attraction of the true solution than standard nonLMM explicit methods. The simple iteration procedure exhibits behavior which is similar to standard nonLMM explicit methods except that spurious steady-state numerical solutions cannot occur. The numerical basins of attraction of the noniterative implicit procedure mimic more closely the basins of attraction of the DEs and are more efficient than the three iterative implicit procedures for the four implicit LMMs. Contrary to popular belief, the initial data using the Newton method of solving the steady part of the DEs may not have to be close to the exact steady state for convergence. These results can be used as an explanation for possible causes and cures of slow convergence and nonconvergence of steady-state numerical solutions when using an implicit LMM time-dependent approach in computational fluid dynamics. C1 UNIV READING,READING RG6 2AX,BERKS,ENGLAND. RP YEE, HC (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 24 TC 20 Z9 20 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 9128, SINGAPORE SN 0218-1274 J9 INT J BIFURCAT CHAOS JI Int. J. Bifurcation Chaos PD DEC PY 1994 VL 4 IS 6 BP 1579 EP 1611 DI 10.1142/S0218127494001210 PG 33 WC Mathematics, Interdisciplinary Applications; Multidisciplinary Sciences SC Mathematics; Science & Technology - Other Topics GA QM159 UT WOS:A1994QM15900011 ER PT J AU CHOUDHURY, BJ DIGIROLAMO, NE AF CHOUDHURY, BJ DIGIROLAMO, NE TI RELATIONS BETWEEN SMMR 37-GHZ POLARIZATION DIFFERENCE AND RAINFALL, AND ATMOSPHERIC CARBON-DIOXIDE CONCENTRATION SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SAHEL; CO2 AB Rainfall and the atmospheric carbon dioxide (CO2) concentration may be considered as proxy variables for spatial and temporal changes of vegetation. Together with theoretical analysis, correlations between these meteorological data and 37 GHz polarization difference (PD) have been studied to test a hypothesis that PD is an indicator of vegetation characteristics. Previously published relations between PD and rainfall, and atmospheric CO2 concentration are discussed in response to issues raised in Tucker (1992) that: (1) the relation between rainfall and PD was based upon selective information, and (2) winter conditions in the more northern latitudes (e.g. snow, low atmospheric water vapour, etc.) result in the appearance of a relation between PD and CO2 concentration. It is shown that: (1) the previously published relation between PD and rainfall is valid at a high level of statistical significance when rainfall stations are screened objectively, and (2) a relationship between PD and CO2 concentration does exist that is not tied to conditions or relationships existent in the winter at northern latitudes. Highly significant correlations between PD and rainfall, and between PD and CO2 concentration would suggest that the hypothesis being tested is true. C1 SCI SYST & APPLICAT INC,LANHAM,MD 20706. RP CHOUDHURY, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,GREENBELT,MD 20771, USA. NR 22 TC 1 Z9 1 U1 0 U2 1 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD DEC PY 1994 VL 15 IS 18 BP 3643 EP 3661 PG 19 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PZ447 UT WOS:A1994PZ44700002 ER PT J AU PATT, FS GREGG, WW AF PATT, FS GREGG, WW TI EXACT CLOSED-FORM GEOLOCATION ALGORITHM FOR EARTH SURVEY SENSORS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID NAVIGATION; IMAGES AB A closed-form solution for geolocation of satellite-based Earth sensor data has been developed. The algorithms are exact, depending only upon the assumption of an ellipsoidal Earth model, and rely on vector and matrix algebra to improve computational efficiency. The values computed are the geodetic coordinates of observed locations (latitude and longitude) and the sensor and solar angles required by radiative transfer models (sensor and solar zenith and azimuth angles). An improvement in computation speed of a factor of two is achieved over a spherical trigonometry solution, along with a much greater accuracy on an ellipsoidal Earth. As much as a factor of six increase in speed is obtained over the more accurate iterative solution for just geodetic latitude and longitude. C1 NASA,GODDARD SPACE FLIGHT CTR,CTR GLOBAL CHANGE DATA,GREENBELT,MD 20771. RP PATT, FS (reprint author), GEN SCI CORP,LAUREL,MD 20707, USA. NR 15 TC 17 Z9 21 U1 0 U2 2 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD DEC PY 1994 VL 15 IS 18 BP 3719 EP 3734 PG 16 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PZ447 UT WOS:A1994PZ44700007 ER PT J AU JOHNSON, LF AF JOHNSON, LF TI MULTIPLE VIEW ZENITH ANGLE OBSERVATIONS OF REFLECTANCE FROM PONDEROSA PINE STANDS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Note ID FOREST CANOPY; MODEL AB Bi-directional reflectance factors (BRF(lambda)) from dense and sparse ponderosa pine (Pinus ponderosa) stands, derived from radiance data collected in the solar principal plane by the Advanced Solid-State Array Spectroradiometer (ASAS), were examined as a function of view zenith angle (B theta(v)). BRF(lambda) was maximized with theta(v) nearest the solar retrodirection, and minimized near the specular direction throughout the ASAS spectral region. The dense stand had much higher BRF anisotropy (maximum BRF/minimum BRF) in the red region than did the sparse stand (relative differences of 5.3 versus 2.75, respectively), as a function of theta(v), due to the shadow component in the canopy. Anisotropy in the near-infrared (NIR) was more similar between the two stands (2.5 in the dense stand and 2.25 in the sparse stand); the dense stand exhibited a greater hotspot effect than the sparse stand in this spectral region. Two common vegetation transforms, the NIR/red ratio and the normalized difference vegetation index (NDVI), both showed a theta(v) dependence for the dense stand. Minimum values occurred near the retrodirection and maximum values occurred near the specular direction. Greater relative differences were noted for the NIR/red ratio than for the NDVI. The sparse stand showed no obvious dependence on theta(v) for either transform, except for slightly elevated values toward the specular direction. RP JOHNSON, LF (reprint author), NASA,AMES RES CTR,JOHNSON CONTROLS WORLD SERV INC,MS 242-4,MOFFETT FIELD,CA 94035, USA. NR 18 TC 11 Z9 11 U1 0 U2 0 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD DEC PY 1994 VL 15 IS 18 BP 3859 EP 3865 PG 7 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PZ447 UT WOS:A1994PZ44700018 ER PT J AU FINN, TT AF FINN, TT TI COOPERATION IN-SPACE SO ISSUES IN SCIENCE AND TECHNOLOGY LA English DT Letter RP FINN, TT (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 SN 0748-5492 J9 ISSUES SCI TECHNOL JI Issues Sci. Technol. PD WIN PY 1994 VL 10 IS 2 BP 10 EP 10 PG 1 WC Engineering, Multidisciplinary; Engineering, Industrial; Multidisciplinary Sciences; Social Issues SC Engineering; Science & Technology - Other Topics; Social Issues GA MQ255 UT WOS:A1994MQ25500009 ER PT J AU SMIALEK, JL ARCHER, FA GARLICK, RG AF SMIALEK, JL ARCHER, FA GARLICK, RG TI TURBINE AIRFOIL DEGRADATION IN THE PERSIAN-GULF-WAR SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Article ID HOT CORROSION AB Helicopter turbine engines used in the Desert Shield and Desert Storm operations experienced excessive sand ingestion. Fine particles were able to bypass filters and proceed through the combustor or cooling gaspaths. The first-stage turbine vanes were impacted with viscous silicate particles, forming a deposit on the leading-edge root platform and resulting in overheating and oxidation. The chemistry of the raw sand determines that of the ingested powders, the deposits and the material reactions. RP SMIALEK, JL (reprint author), NASA,LEWIS RES CTR,MAIL STOP 106-1,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 14 TC 36 Z9 38 U1 1 U2 5 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 DEC PY 1994 VL 46 IS 12 BP 39 EP 41 PG 3 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA QU356 UT WOS:A1994QU35600011 ER PT J AU KEDEM, B PAVLOPOULOS, H GUAN, XD SHORT, DA AF KEDEM, B PAVLOPOULOS, H GUAN, XD SHORT, DA TI A PROBABILITY-DISTRIBUTION MODEL FOR RAIN RATE SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article; Proceedings Paper CT 4th International Conference on Precipitation - Hydrological and Meteorological Aspects of Rainfall Measurement and Predictability CY APR 26-28, 1993 CL UNIV IOWA, IOWA CITY, IA SP AMER METEOROL SOC, AMER GEOPHYS UNION HO UNIV IOWA ID THRESHOLD METHOD; RADAR AB A systematic approach is suggested for modeling the probability distribution of rain rate. Rain rate, conditional on rain and averaged over a region, is modeled as a temporally homogeneous diffusion process with appropriate boundary conditions. The approach requires a drift coefficient-conditional average instantaneous rate of change of rain intensity-as well as a diffusion coefficient-the conditional average magnitude of the rate of growth and decay of rain rate about its drift. Under certain assumptions on the drift and diffusion coefficients compatible with rain rate, a new parametric family-containing the lognormal distribution-is obtained for the continuous part of the stationary limit probability distribution. The family is fitted to tropical rainfall from Darwin and Florida, and it is found that the lognormal distribution provides adequate fits as compared with other members of the family and also with the gamma distribution. C1 UNIV MARYLAND,DEPT MATH,COLLEGE PK,MD 20742. UNIV MARYLAND,INST SYST RES,COLLEGE PK,MD 20742. UNIV AEGEAN,DEPT MATH,SAMOS,GREECE. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. NR 25 TC 26 Z9 26 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 DEC PY 1994 VL 33 IS 12 BP 1486 EP 1493 DI 10.1175/1520-0450(1994)033<1486:APDMFR>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PW580 UT WOS:A1994PW58000009 ER PT J AU KUMAR, P FOUFOULA-GEORGIOU, E AF KUMAR, P FOUFOULA-GEORGIOU, E TI CHARACTERIZING MULTISCALE VARIABILITY OF ZERO INTERMITTENCY IN SPATIAL RAINFALL SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article AB In this paper the authors study how zero intermittency in spatial rainfall, as described by the fraction of area covered by rainfall, changes with spatial scale of rainfall measurement or representation. A statistical measure of intermittency that describes the size distribution of ''voids'' (nonrainy areas imbedded inside rainy areas) as a function of scale is also introduced. Morphological algorithms are proposed for reconstructing rainfall intermittency at fine scales given the intermittency at coarser scales. These algorithms are envisioned to be useful in hydroclimatological studies where the rainfall spatial variability at the subgrid scale needs to be reconstructed from the results of synoptic- or mesoscale meteorological numerical models. The developed methodologies are demonstrated and tested using data from a severe springtime midlatitude squall line and a mild midlatitude winter storm monitored by a meteorological radar in Norman, Oklahoma. C1 UNIV MINNESOTA, DEPT CIVIL & MINERAL ENGN, ST ANTHONY FALLS HYDRAUL LAB, MINNEAPOLIS, MN 55455 USA. RP KUMAR, P (reprint author), NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, HYDROL SCI BRANCH, CODE 974, GREENBELT, MD 20771 USA. RI Kumar, Praveen/D-2036-2010 OI Kumar, Praveen/0000-0002-4787-0308 NR 5 TC 18 Z9 18 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD DEC PY 1994 VL 33 IS 12 BP 1516 EP 1525 DI 10.1175/1520-0450(1994)033<1516:CMVOZI>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PW580 UT WOS:A1994PW58000012 ER PT J AU RAGHAVAN, R CHANDRASEKAR, V AF RAGHAVAN, R CHANDRASEKAR, V TI MULTIPARAMETER RADAR STUDY OF RAINFALL - POTENTIAL APPLICATION TO AREA-TIME INTEGRAL STUDIES SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article; Proceedings Paper CT 4th International Conference on Precipitation - Hydrological and Meteorological Aspects of Rainfall Measurement and Predictability CY APR 26-28, 1993 CL UNIV IOWA, IOWA CITY, IA SP AMER METEOROL SOC, AMER GEOPHYS UNION HO UNIV IOWA ID THRESHOLD METHOD AB Multiparameter radars measure one or more additional parameters in addition to the conventional reflectivity factor. The combination of radar observations from a multiparameter radar is used to study the time evolution of rainstorms. A technique is presented to self-consistently compare the area-time integral (ATI) and rainfall volume estimates from convective storms, using two different measurements from a multiparameter radar. Rainfall volumes for the lifetime of individual storms are computed using the reflectivity at S band (10-cm wavelength) as well as one-way specific attenuation at X band (3-cm wavelength). Area-time integrals are computed by summing all areas in each radar snapshot having reflectivities (S band) in excess of a preselected threshold. The multiparameter radar data used in this study were acquired by the NCAR CP-2 radar during the Cooperative Huntsville Meteorological Experiment (COHMEX) and the Convection and Precipitation/ Electrification Experiment (CaPE), respectively. ATI studies were accomplished in this work using multiparameter radar data acquired during the lifetime of six convective events that occurred in the COHMEX radar coverage area. A case study from the COHMEX field campaign (20 July 1986) was selected to depict the various stages in the evolution of a storm over which the ATI and rainfall volume computations were performed using multiparameter radar data. Another case study from the CaPE held campaign (12 August 1991) was used to demonstrate the evolution of a convective cell based on differential reflectivity observations. C1 COLORADO STATE UNIV,FT COLLINS,CO 80523. RP RAGHAVAN, R (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,INST GLOBAL CHANGE RES & EDUC,CODE ES42,HUNTSVILLE,AL 35812, USA. NR 30 TC 4 Z9 4 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD DEC PY 1994 VL 33 IS 12 BP 1636 EP 1645 DI 10.1175/1520-0450(1994)033<1636:MRSORP>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PW580 UT WOS:A1994PW58000022 ER PT J AU LAMB, JL NAGENDRA, CL AF LAMB, JL NAGENDRA, CL TI SEMICONDUCTOR-METAL GRADED-INDEX COMPOSITE THIN-FILMS FOR INFRARED APPLICATIONS SO JOURNAL OF APPLIED PHYSICS LA English DT Article RP LAMB, JL (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD DEC 1 PY 1994 VL 76 IS 11 BP 7195 EP 7200 DI 10.1063/1.358000 PG 6 WC Physics, Applied SC Physics GA PU818 UT WOS:A1994PU81800004 ER PT J AU GOLDBERGER, AL MIETUS, JE RIGNEY, DR WOOD, ML FORTNEY, SM AF GOLDBERGER, AL MIETUS, JE RIGNEY, DR WOOD, ML FORTNEY, SM TI EFFECTS OF HEAD-DOWN BED REST ON COMPLEX HEART-RATE-VARIABILITY - RESPONSE TO LBNP TESTING SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE AUTONOMIC FUNCTION; NONLINEAR DYNAMICS; ORTHOSTATIC TOLERANCE; SPACEFLIGHT; LOWER BODY NEGATIVE PRESSURE ID BODY NEGATIVE-PRESSURE; EARLY CARDIOVASCULAR ADAPTATION; RATE SPECTRAL-ANALYSIS; SUDDEN CARDIAC DEATH; ORTHOSTATIC HYPOTENSION; ZERO GRAVITY; DYNAMICS AB Head-down bed rest is used to model physiological changes during spaceflight. We postulated that bed rest would decrease the degree of complex physiological heart rate variability. We analyzed continuous heart rate data from digitized Holter recordings in eight healthy female volunteers (age 28-34 yr) who underwent a 13-day 6 degrees head-down bed rest study with serial lower body negative pressure (LBNP) trials. Heart rate variability was measured on 4-min data sets using conventional time and frequency domain measures as well as with a new measure of signal ''complexity'' (approximate entropy). Data were obtained pre-bed rest (control), during bed rest (day 4 and day 9 or 11), and 2 days post-bed rest (recovery). Tolerance to LBNP was significantly (P < 0.02) reduced on both bed rest days vs. pre-bed rest. Heart rate variability was assessed at peak LBNP. Heart rate approximate entropy was significantly (P < 0.05) decreased at day 4 and day 9 or 11, returning toward normal during recovery. Heart rate standard deviation and the ratio of high- to low-power frequency did not change significantly. We conclude that short-term bed rest is associated with a decrease in the complex variability of heart rate during LBNP testing in healthy young adult women. Measurement of heart rate complexity, using a method derived from nonlinear dynamics (''chaos theory''), may provide a sensitive marker of this loss of physiological variability, complementing conventional time and frequency domain statistical measures. C1 HARVARD UNIV,SCH MED,BOSTON,MA 02215. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP GOLDBERGER, AL (reprint author), BETH ISRAEL HOSP,DIV CARDIOVASC GZ-435,330 BROOKLINE AVE,BOSTON,MA 02215, USA. FU NHLBI NIH HHS [R01-HL-42172] NR 32 TC 36 Z9 37 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD DEC PY 1994 VL 77 IS 6 BP 2863 EP 2869 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA PX993 UT WOS:A1994PX99300053 PM 7896633 ER PT J AU NI, CK FLYNN, GW GREEN, S AF NI, CK FLYNN, GW GREEN, S TI EXPERIMENTAL AND THEORETICAL VELOCITY PROFILES FOR PURE ROTATIONAL SCATTERING - CO HOT HYDROGEN-ATOM COLLISIONS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID DIFFERENTIAL CROSS-SECTIONS; DIODE-LASER SPECTROSCOPY; HD-NE COLLISIONS; ANISOTROPIC INTERACTION; EXCITATION; PHOTODISSOCIATION; HCO; H2S; DISTRIBUTIONS; CONTINUUM C1 COLUMBIA UNIV,COLUMBIA RADIAT LAB,NEW YORK,NY 10027. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP NI, CK (reprint author), COLUMBIA UNIV,DEPT CHEM,NEW YORK,NY 10027, USA. RI Ni, Chi-Kung/F-7920-2012 NR 29 TC 7 Z9 7 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 DEC 1 PY 1994 VL 101 IS 11 BP 9499 EP 9505 DI 10.1063/1.467980 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PV956 UT WOS:A1994PV95600034 ER PT J AU LYNCHSTIEGLITZ, M AF LYNCHSTIEGLITZ, M TI THE DEVELOPMENT AND VALIDATION OF A SIMPLE SNOW MODEL FOR THE GISS GCM SO JOURNAL OF CLIMATE LA English DT Article ID COVER; TEMPERATURE; DROUGHT AB Five years of meteorological and hydrological data from a typical New England watershed where winter snow cover is significant were used to drive and validate two off-line land surface schemes suitable for use in the Goddard Institute for Space Studies GCM: a baseline scheme that does not model the physics of a snowpack and therefore, neglects the insulating properties of snow cover; and a modified scheme in which a three-layer snowpack is modeled. Comparing baseline model results with validation data reveals several model deficiencies. Surface radiation temperatures could not adequately be modeled and the ground froze to unreasonable depths. Furthermore, because of ground cooling resulting from large surface heat fluxes to the atmosphere from the uninsulated surface, deeper model layers did not unfreeze until midsummer. As such, the normal hydrologic processes of runoff, ground water infiltration, and movement, etc., are compromised for a good part of the year. With the inclusion of a simple three-layer snow model into the baseline model, not only are the ground and surface radiation temperatures adequately modeled but all the features of snowpack ripening that characterize pack growth/ablation are simulated. RP LYNCHSTIEGLITZ, M (reprint author), COLUMBIA UNIV,DEPT GEOL SCI,NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 22 TC 122 Z9 128 U1 1 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD DEC PY 1994 VL 7 IS 12 BP 1842 EP 1855 DI 10.1175/1520-0442(1994)007<1842:TDAVOA>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QC226 UT WOS:A1994QC22600003 ER PT J AU CHOU, MD AF CHOU, MD TI RADIATION BUDGETS IN THE WESTERN TROPICAL PACIFIC SO JOURNAL OF CLIMATE LA English DT Article ID LONGWAVE RADIATION; SURFACE RADIATION; SOLAR-RADIATION; TRANSMISSION FUNCTIONS; SATELLITE DATA; SCANNER DATA; WATER-VAPOR; CLIMATE; PARAMETERIZATIONS; CLOUDS AB The usefulness of the radiances measured by operational satellites in deriving radiation budgets is demonstrated by comparing the model calculations with the Earth Radiation Budget Experiment (ERBE) fluxes. The radiation budgets in the atmosphere and at the surface in the western tropical Pacific are computed by coupling radiative transfer models to satellite retrievals of cloud and the earth surface parameters for April 1985 and April 1987. The model-computed fluxes at the top of the atmosphere agree well with the ERBE fluxes in both the solar and IR spectral regions. The difference is <10 W m(-2) in the outgoing longwave flux and <15 W m(-2) in the net downward shortwave flux. The agreement indicates that long-term earth radiation budgets in the tropical Pacific can be computed using the radiances measured by operational satellites. RP CHOU, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 37 TC 9 Z9 9 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD DEC PY 1994 VL 7 IS 12 BP 1958 EP 1971 DI 10.1175/1520-0442(1994)007<1958:RBITWT>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QC226 UT WOS:A1994QC22600011 ER PT J AU HARSHVARDHAN WIELICKI, BA GINGER, KM AF HARSHVARDHAN WIELICKI, BA GINGER, KM TI THE INTERPRETATION OF REMOTELY-SENSED CLOUD PROPERTIES FROM A MODEL PARAMETERIZATION PERSPECTIVE SO JOURNAL OF CLIMATE LA English DT Article ID SHAPED OPTICAL MEDIA; RADIATIVE-TRANSFER; THRESHOLD METHOD; CLIMATE MODELS; COVER; RESOLUTION; VERIFICATION; ATMOSPHERES; CONVECTION; PREDICTION AB A study has been made of the relationship between mean cloud radiative properties and cloud fraction in stratocumulus cloud systems. The analysis is of several Land Resources Satellite System (LANDSAT) images and three hourly International Satellite Cloud Climatology Project (ISCCP) C-l data during daylight hours for two grid boxes covering an area typical of a general circulation model (GCM) grid increment. Cloud properties were inferred from the LANDSAT images using two thresholds and several pixel resolutions ranging from roughly 1/16 km to 8 km. At the finest resolution, the analysis shows that mean cloud optical depth (or liquid water path) increases somewhat with increasing cloud fraction up to 20% cloud coverage. More striking, however, is the lack of correlation between the two quantities for cloud fractions between roughly 0.2 and 0.8. When the scene is essentially overcast, the mean cloud optical depth tends to be higher. Coarse resolution LANDSAT analysis and the ISCCP g-km data show lack of correlation between mean cloud optical depth and cloud fraction for coverage less than about 90%. This study shows that there is perhaps a local mean liquid water path (LWP) associated with partly cloudy areas of stratocumulus clouds. A method has been suggested to use this property to construct the cloud fraction parameterization in a GCM when the model computes a grid-box-mean LWP. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. PURDUE UNIV, DEPT EARTH & ATMOSPHER SCI, W LAFAYETTE, IN 47907 USA. RP HARSHVARDHAN (reprint author), PURDUE UNIV, DEPT EARTH & ATMOSPHER SCI, W LAFAYETTE, IN 47907 USA. NR 41 TC 8 Z9 8 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 EI 1520-0442 J9 J CLIMATE JI J. Clim. PD DEC PY 1994 VL 7 IS 12 BP 1987 EP 1998 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QC226 UT WOS:A1994QC22600013 ER PT J AU DUYAR, A ELDEM, V MERRILL, W GUO, TH AF DUYAR, A ELDEM, V MERRILL, W GUO, TH TI A SIMPLIFIED DYNAMIC-MODEL OF THE SPACE-SHUTTLE MAIN ENGINE SO JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME LA English DT Note AB This paper presents a simplified model of the space shuttle main engine (SSME) dynamics valid within the range of operation of the engine. This model is obtained by linking the linearized point models obtained at 25 different operating points of the SSME. The simplified model was developed for use with a model-based diagnostic scheme for failure detection and diagnostics studies, as well as control design purposes. This simplified model was tested by designing an input signal which covers the whole range of operating points considered and then comparing the responses of linked model and the nonlinear simulation. The comparison indicated good agreement between these responses. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP DUYAR, A (reprint author), FLORIDA ATLANTIC UNIV,DEPT MECH ENGN,BOCA RATON,FL 33431, USA. NR 5 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 DEC PY 1994 VL 116 IS 4 BP 815 EP 819 DI 10.1115/1.2899286 PG 5 WC Automation & Control Systems; Instruments & Instrumentation SC Automation & Control Systems; Instruments & Instrumentation GA QA491 UT WOS:A1994QA49100033 ER PT J AU ZHU, J SHIH, TH AF ZHU, J SHIH, TH TI A NUMERICAL STUDY OF CONFINED TURBULENT JETS SO JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article AB A numerical investigation is reported of turbulent incompressible jets confined in two ducts, one cylindrical and the other conical with a 5 deg divergence. In each case, three Craya-Curtet numbers are considered which correspond, respectively, to flow situations with no, moderate, and strong recirculation. Turbulence closure is achieved by using the K-epsilon model and a recently proposed realizable Reynolds stress algebraic equation model. Calculations are carried out with a finite-volume procedure. Second-order accurate differencing schemes and sufficiently fine grids are used to ensure numerical accuracy. The calculated results are compared with experimental data. It is shown that the numerical methods presented are capable of capturing the essential flow features observed in the experiments and that the realizable Reynolds stress algebraic equation model performs better than the K-epsilon model for this class of flows. RP ZHU, J (reprint author), NASA,LEWIS RES CTR,ICOMP,CTR MODELING TURBULENCE & TRANSIT,CLEVELAND,OH 44135, USA. NR 14 TC 5 Z9 6 U1 1 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0098-2202 J9 J FLUID ENG-T ASME JI J. Fluids Eng.-Trans. ASME PD DEC PY 1994 VL 116 IS 4 BP 702 EP 706 DI 10.1115/1.2911838 PG 5 WC Engineering, Mechanical SC Engineering GA QA169 UT WOS:A1994QA16900005 ER PT J AU GERMANY, GA TORR, DG RICHARDS, PG TORR, MR JOHN, S AF GERMANY, GA TORR, DG RICHARDS, PG TORR, MR JOHN, S TI DETERMINATION OF IONOSPHERIC CONDUCTIVITIES FROM FUV AURORAL EMISSIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CHARACTERISTIC ELECTRON-ENERGY; NEUTRAL ATMOSPHERE; E-REGION; THERMOSPHERIC MODEL; TIME CONDUCTANCES; F-REGION; DEPENDENCE; IMAGES; CONVECTION; IONIZATION AB The purpose of this paper is to examine the viability of using LBH emission ratios to infer amoral conductances and to quantify the strengths and weaknesses of this technique. We show that column-integrated Hall and Pedersen conductances may be determined from a single remote measurement of a pair of amoral LBH emissions, one in the region of strong O-2 absorption (1464 Angstrom) and one lying outside of this region (1838 Angstrom). The dependence of the determined conductivities on incident average energy, total energy flux, and changes in solar and magnetic activity levels is examined. We show that, for energies above 5 keV, amoral conductances may be scaled by the square root of the incident energy flux with errors less than about 20%. For lower energies, however, the scaling may deviate significantly from a power of 0.5. We provide appropriate scaling factors as a function of average energy. We also note that the choice of either a Gaussian or Maxwellian distribution can significantly affect low-energy (<1 keV) conductance calculations. Finally, we quantify the conditions under which the mean energy of a Gaussian energy distribution may differ significantly from the characteristic energy. C1 UNIV ALABAMA,CTR SPACE PLASMA & AERONOM RES,DEPT COMP SCI,OPT AERON LAB,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP GERMANY, GA (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERONOM RES,DEPT PHYS,OPT AERON LAB,HUNTSVILLE,AL 35899, USA. NR 46 TC 33 Z9 35 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 DEC 1 PY 1994 VL 99 IS A12 BP 23297 EP 23305 DI 10.1029/94JA02038 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400007 ER PT J AU MELENDEZALVIRA, DJ BURNSIDE, RG WALKER, JCG AF MELENDEZALVIRA, DJ BURNSIDE, RG WALKER, JCG TI MODELING THE ARECIBO NIGHTTIME F2 LAYER .2. IONOSPHERIC GRADIENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MIDNIGHT TEMPERATURE MAXIMUM; F-REGION; ELECTRIC-FIELDS; NEUTRAL WINDS; OPTICAL OBSERVATIONS; THERMOSPHERE; PROPAGATION; DYNAMICS AB The servo model is extended and used to fit horizontal gradients in the F-2 layer height and density and to estimate the zonal Pedersen current and its zonal and meridional gradient. Horizontal gradients were measured from the Arecibo Observatory during the following five nights: August 16-17 and 17-18, 1982; and October 4-5, 5-6, and 9-10, 1983. The model gradients are driven by nonzero current gradients, which are applied as needed to fit the measured gradients in the F-2 peak. The gradient in the peak height is accurately reproduced; the peak density gradient is calculated self-consistently in the model. The divergence of the Pedersen current can be deduced when the current flows zonally and is found to differ from zero. This is a consequence of zonal divergence of the model zonal current. Expressions are derived for the divergence of the Hall current and for the curl of the current in the presence of ionospheric gradients. The vertical vorticity of the F region current is determined from the radar and optical measurements and the mass spectrometer/incoherent scatter (MSIS) neutral densities. Both neutral and plasma motions generate current vorticity equally as expected from the F region dynamo. The measured velocity gradients produce more current gradients and vorticity than the measured conductance gradients. The measured height gradient in the perpendicular-north plasma drift (partial derivative(z) nu perpendicular to N) is the dominant term in the vorticity and drives the two current shears that cause vorticity. Geometrical factors increase (partial derivative(z) nu perpendicular to N) by about 13% in the zonal gradient of the meridional current over the meridional gradient of the zonal current. This causes anticorrelation between the former current shear and the vorticity. The two measured shears generally follow each other, have opposing vorticities and large uncertainties. The nighttime current may be irrotational or have constant vorticity. Large current gradients occur in conjunction with observed descents of the F-2 peak height. The gradients are interpreted as due to the midnight pressure bulge at low latitudes. Short-period gravity waves of meteorological origin are ruled out as they were not observed and are Limited in their ability to reach ionospheric heights. The harmonic analysis used to obtain horizontal wind gradients is largely unaffected by spatially uniform wind accelerations. Therefore the deduced spatial variations in the measured winds are unlikely to be due to temporal variations. C1 ARECIBO OBSERV,ARECIBO,PR. UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP MELENDEZALVIRA, DJ (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375, USA. NR 49 TC 3 Z9 3 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 DEC 1 PY 1994 VL 99 IS A12 BP 23307 EP 23327 DI 10.1029/94JA01812 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400008 ER PT J AU WINTERHALTER, D NEUGEBAUER, M GOLDSTEIN, BE SMITH, EJ BAME, SJ BALOGH, A AF WINTERHALTER, D NEUGEBAUER, M GOLDSTEIN, BE SMITH, EJ BAME, SJ BALOGH, A TI ULYSSES FIELD AND PLASMA OBSERVATIONS OF MAGNETIC HOLES IN THE SOLAR-WIND AND THEIR RELATION TO MIRROR-MODE STRUCTURES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EARTHS MAGNETOSHEATH; WAVES; INSTABILITY; MAGNETOSPHERE; DEPLETION; SHOCK AB The term ''magnetic hole'' has been used to denote isolated intervals when the magnitude of the interplanetary magnetic field drops to a few tenths, or less, of its ambient value for a time that corresponds to a linear dimension of tens to a few hundreds of proton gyro-radii. Data obtained by the Ulysses magnetometer and solar wind analyzer have been combined to study the properties of such magnetic holes in the solar wind between 1 AU and 5.4 AU and to 23 degrees south latitude. In order to avoid confusion with decreases in field strength at interplanetary discontinuities, the study has focused on linear holes across which the field direction changed by less than 5 degrees. The holes occurred preferentially, but not without exception, in the interaction regions on the leading edges of highspeed solar wind streams. Although the plasma surrounding the holes was generally stable against the mirror instability, there are indications that the holes may have been remnants of mirror-mode structures created upstream of the points of observation. Those indications include the following: (1) For the few holes for which proton or alpha-particle pressure could be measured inside the hole, the ion thermal pressure was always greater than in the plasma adjacent to the holes. (2) The plasma surrounding many of the holes was marginally table for the mirror mode, while the plasma envitonmen?t of all the holes was significantly closer to mirror instability than was the average salar wind. (3) The plasma containing trains of closely spaced holes was closer to mirror instability tl;an was the plasma containing isolated holes. (4) The near-hole plasma had much higher ion beta (ratio of thermal to magnetic pressure) than did the average solar wind. (5) Near the holes, T-perpendicular to/T-II tended tb be either >1 or larger than in the average wind. (6) The proton and alpha-particle distribution function's measured inside the holes occasionally exhibited the flattened phase-space-density contours in nu(perpendicular to)-nu(II) space found in some numerical simulations of the mirror instability. C1 LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. UNIV LONDON IMPERIAL COLL SCI & TECHNOL,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. RP WINTERHALTER, D (reprint author), CALTECH,JET PROP LAB,MS 169-506,4800 OAK GROVE DR,PASADENA,CA, USA. NR 36 TC 131 Z9 133 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD DEC 1 PY 1994 VL 99 IS A12 BP 23371 EP 23381 DI 10.1029/94JA01977 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400014 ER PT J AU YOON, PH WU, CS VINAS, AF REINER, MJ FAINBERG, J STONE, RG AF YOON, PH WU, CS VINAS, AF REINER, MJ FAINBERG, J STONE, RG TI THEORY OF 2-OMEGA(PE) RADIATION-INDUCED BY THE BOW SHOCK SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PERPENDICULAR COLLISIONLESS SHOCKS; PLASMA WAVES UPSTREAM; SOLAR-WIND; ELECTRON ACCELERATION; ISEE OBSERVATIONS; FORESHOCK; EARTH; FREQUENCY; NOISE AB A new radiation emission mechanism is proposed to explain electromagnetic radiation observed at twice the electron plasma frequency, 2w(pe), in the upstream region of the Earth's bow shock. This radiation has its origin at the electron foreshock boundary where energetic electron beams and intense narrow-band Langmuir waves are observed. The proposed emission mechanism results from the interaction of the electron beam-and Langmuir waves that are backscattered off thermal ions. This interaction is described by a nonlinear dispersion equation which incorporates an effect owing to electron trajectory modulation by the backscattered Langmuir waves. Subsequent analysis of the dispersion equation reveals two important consequences. First, a long-wavelength electrostatic quasi-mode with frequency at 2w(pe) is excited, and second, the quasi-mode and the electromagnetic mode are nonlinearly coupled. The implication is that, when the excited 2w(pe) quasi-mode propagates in an inhomogeneous medium with slightly decreasing density, the quasi-mode can be converted directly into an electromagnetic mode. Hence the electromagnetic radiation at twice the plasma frequency is generated. Numerical solutions of the dispersion equation with the choice of parameters that describe physical characteristics of the electron foreshock are presented, which illustrates the viability of the new mechanism. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. HUGHES STX,LANHAM,MD. RP YOON, PH (reprint author), UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20742, USA. RI Yoon, Peter/E-2395-2013 NR 24 TC 27 Z9 27 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 DEC 1 PY 1994 VL 99 IS A12 BP 23481 EP 23488 DI 10.1029/94JA02489 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400024 ER PT J AU KROGULEC, M MUSIELAK, ZE SUESS, ST NERNEY, SF MOORE, RL AF KROGULEC, M MUSIELAK, ZE SUESS, ST NERNEY, SF MOORE, RL TI REFLECTION OF ALFVEN WAVES IN THE SOLAR-WIND SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD; CORONAL HOLES; ATMOSPHERE; ACCELERATION; PROPAGATION AB We have revisited the problem of propagation of toroidal and linear Alfven waves formulated by Heinemann and Olbert (1980) to compare WKB and non-WKB waves and their effects on the solar wind. They considered two solar wind models and showed that reflection is important for Alfven waves with periods of the order of one day and longer and that non-WKB Alfven waves are no more effective in accelerating the solar wind than WKB waves. There are several recently published papers that seem to indicate that Alfven waves with periods of the order of several minutes should be treated as non-WKB waves and that these non-WKB waves exert a stronger acceleration force than WKB waves. The purpose of this paper is to study the origin of these discrepancies by performing parametric studies of the behavior of the waves under a variety of different conditions. In addition, we want to investigate two problems that have not been addressed by Heinemann and Olbert, namely, calculate the efficiency of Alfven wave reflection by using the reflection coefficient and identify the region of strongest wave reflection in different wind models. To achieve these goals, we investigated the influence of temperature, electron density distribution, wind velocity, and magnetic field strength on the waves. The obtained results clearly demonstrate that Alfven wave reflection is strongly model dependent and that the strongest reflection can be expected in models with the base temperatures higher than 10(6) K and with the base densities lower than 7 x 10(7) cm(-3). Ln these models as well as in the models with lower temperatures and higher densities, Alfven waves with periods as short as several minutes have negligible reflection so that they can be treated as WKB waves; however, for Alfven waves with periods of the order of one hour or longer reflection is significant, requiring a non-WKB treatment. We also show that non-WKB, Linear Alfven waves are always less effective in accelerating the plasma than WKB Alfven waves. Finally, it is evident from our results that the region of strongest wave reflection is usually located at the base of the models and hence that interpretation of wave reflection based solely on the reflection coefficient can be misleading. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV GDANSK,INST THEORET PHYS & ASTROPHYS,PL-80952 GDANSK,POLAND. UNIV GDANSK,DEPT AEROSP & MECH ENGN,GDANSK,POLAND. RP KROGULEC, M (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERONOM RES,HUNTSVILLE,AL 35899, USA. NR 34 TC 29 Z9 29 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 DEC 1 PY 1994 VL 99 IS A12 BP 23489 EP 23501 DI 10.1029/94JA02209 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400025 ER PT J AU LIN, NG KELLOGG, PJ THIESSEN, JP LENGYELFREY, D TSURUTANI, BT PHILLIPS, JL AF LIN, NG KELLOGG, PJ THIESSEN, JP LENGYELFREY, D TSURUTANI, BT PHILLIPS, JL TI WHISTLER-MODE WAVES IN THE JOVIAN MAGNETOSHEATH SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EARTHS BOW SHOCK; LION ROARS; ULYSSES OBSERVATIONS; IO TORUS; PLASMA; TURBULENCE; JUPITER AB During the Ulysses flyby of Jupiter in February 1992, the spacecraft traversed the Jovian magnetosheath for a few hours during the inbound pass and for a few days during the outbound pass. Burstlike electromagnetic waves at frequencies of similar to 0.1-0.4 of the local electron cyclotron frequency have been observed by the Unified Radio and Plasma Wave (URAP) experiment. The waves were more often observed in the regions which were probably the outer or middle magnetosheath, especially near the bow shock, and rarely seen in the magnetosphere/magnetosheath boundary layer. The propagation angles of the waves are estimated-by comparing the measurements of the wave electric and magnetic fields in the spacecraft spin plane with the corresponding values calculated using the cold plasma dispersion relation under local field and plasma conditions. It is found that the waves propagate obliquely with wave angles between similar to 30 degrees and 50 degrees. These waves are likely to be the whistler mode waves which are excited by suprathermal electrons with a few hundred eV and a slight anisotropy (T-perpendicular to/T-parallel to similar to 1.1-1.5). They are probably similar in nature to the lion roars observed in the Earth's magnetosheath. Signature of coupling between the mirror mode and the whistler mode have also been observed. The plasma conditions which favor the excitation of the whistler mode instability during the wave events exist as observed by the plasma experiment of Ulysses. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP LIN, NG (reprint author), UNIV MINNESOTA,SCH PHYS & ASTRON,116 CHURCH ST SE,MINNEAPOLIS,MN 55455, USA. NR 33 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD DEC 1 PY 1994 VL 99 IS A12 BP 23527 EP 23539 DI 10.1029/94JA01998 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400030 ER PT J AU SERGEEV, VA PULKKINEN, TI PELLINEN, RJ TSYGANENKO, NA AF SERGEEV, VA PULKKINEN, TI PELLINEN, RJ TSYGANENKO, NA TI HYBRID STATE OF THE TAIL MAGNETIC-CONFIGURATION DURING STEADY CONVECTION EVENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SUBSTORM GROWTH-PHASE; PLASMA SHEET; MAGNETOSPHERIC CONVECTION; EARTHS MAGNETOTAIL; FIELD MODEL; FLUX TUBES; BOUNDARY; AVERAGE; RE AB Previous observations have shown that during periods of steady magnetospheric convection (SMC) a large amount of magnetic flux crosses the plasma sheet (corresponding to similar to 10 degrees wide auroral oval at the nightside) and that the magnetic configuration in the midtail is relaxed (the current sheet is thick and contains enhanced B-Z). These signatures are typical for the substorm recovery phase. Using near-geostationary magnetic field data, magnetic field modeling, and a novel diagnostic technique (isotropic boundary algorithm), we show that in the near-Earth tail the magnetic configuration is very stretched during the SMC events. This stretching is caused by an intense, thin westward current. Because of the strongly depressed B-Z, there is a large radial gradient in the near-tail magnetic field. These signatures have been previously associated only with the substorm growth phase. Our results indicate that during the SMC periods the magnetic configuration is very peculiar, with co-existing thin near-Earth current sheet and thick midtail plasma sheet. The deep local minimum of the equatorial B-Z that develops at R similar to 12 R(E) is consistent with steady, adiabatic, Earthward convection in the midtail. These results impose constraints on the existing substorm theories, and call for an explanation of how such a stressed configuration can persist for such along time without tail current disruptions that occur at the end of a substorm growth phase. C1 FINNISH METEOROL INST, SF-00101 HELSINKI, FINLAND. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RI Tsyganenko, Nikolai/J-7377-2012; Pulkkinen, Tuija/D-8403-2012; Sergeev, Victor/H-1173-2013 OI Tsyganenko, Nikolai/0000-0002-5938-1579; Pulkkinen, Tuija/0000-0002-6317-381X; Sergeev, Victor/0000-0002-4569-9631 NR 24 TC 64 Z9 64 U1 0 U2 3 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 DEC 1 PY 1994 VL 99 IS A12 BP 23571 EP 23582 DI 10.1029/94JA01980 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400034 ER PT J AU NAKAMURA, R BAKER, DN FAIRFIELD, DH MITCHELL, DG MCPHERRON, RL HONES, EW AF NAKAMURA, R BAKER, DN FAIRFIELD, DH MITCHELL, DG MCPHERRON, RL HONES, EW TI PLASMA-FLOW AND MAGNETIC-FIELD CHARACTERISTICS NEAR THE MIDTAIL NEUTRAL SHEET SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EARTHS MAGNETOTAIL; EQUATORIAL MAGNETOTAIL; ION COMPOSITION; SUBSTORM; RECONNECTION; MAGNETOSPHERE; AMPTE/CCE; MODEL; OVAL; RE AB Using IMP 6, 7, and 8 magnetic field and plasma data, we have determined statistical occurrence properties of bulk flow and magnetic field orientation near the midtail. neutral sheet. Characteristics of bulk plasma flow and magnetic field significantly change according to the radial distance down the tail. High-speed flow events (V > 300 km/s) are essentially restricted to the region tailward of X = -25 R(E) and are predominantly sunward or tailward. The low-speed flows were nearly equally likely to be in any direction, with the occurrence rate of duskward and sunward flow being larger than that of tailward and dawnward flow. Duskward now occurrence is highest in the region Earthward of X = -25 R(E), while sunward flow occurrence is highest in the region tailward of X = -25 R(E). The significance of the dawn-to-dusk flow in the near-Earth region obtained in our study supports the idea that there exists a very effective mechanism to accelerate ions in the dawn-to-dusk direction and hence the relief of pressure buildup in the near-Earth region. During high-speed flow events the relationship between B-Z polarity and plasma flow direction is largely consistent with that expected from the magnetic reconnection processes associated with substorms. There are also significant numbers of negative B-Z events that are not associated with tailward flow. Mechanism other than substorm neutral line should therefore also taken into account to explain general B-Z polarity in the midtail region. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. LOS ALAMOS NATL LAB,LOS ALAMOS,NM. RP NAKAMURA, R (reprint author), NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,3-13 HONOHARA,TOYOKAWA,AICHI 442,JAPAN. RI Nakamura, Rumi/I-7712-2013 OI Nakamura, Rumi/0000-0002-2620-9211 NR 40 TC 33 Z9 33 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 DEC 1 PY 1994 VL 99 IS A12 BP 23591 EP 23601 DI 10.1029/94JA02082 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400036 ER PT J AU WEIMER, DR CRAVEN, JD FRANK, LA HANSON, WB MAYNARD, NC HOFFMAN, RA SLAVIN, JA AF WEIMER, DR CRAVEN, JD FRANK, LA HANSON, WB MAYNARD, NC HOFFMAN, RA SLAVIN, JA TI SATELLITE MEASUREMENTS THROUGH THE CENTER OF A SUBSTORM SURGE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IONOSPHERIC ELECTRIC-FIELDS; TWO-DIMENSIONAL OBSERVATIONS; WESTWARD TRAVELING SURGE; ALIGNED CURRENT REGIONS; SUBAURORAL ION DRIFTS; AURORAL-ZONE CURRENTS; CONDUCTANCES; ROCKET; MODEL AB Measurements have been made of electric and magnetic fields, plasma drifts, and electron precipitation within a surge at the westward, leading edge of the auroral ''bulge'' at the peak of the substorm expansion phase. The trajectory of the DE 2 satellite over the auroral emissions is determined from nearly simultaneous observations with the imager on the DE 1 satellite at a higher altitude. The electric field and plasma drift measurements have enabled us to deduce the basic configuration of the ionospheric electric potential, or plasma convection, around the surge. The electric potential shows that the bulge is associated with a protrusion of the dawn convection cell into the dusk cell, poleward of the ''Harang discontinuity.'' This protrusion contains a westward electric field that strongly enhances the westward electrojet current by the creation of a ''Cowling channel.'' This westward electric field, and the associated Cowling current, appear to terminate within the surge, which contains an intense, upward field-aligned current. The magnetic field measurements show that the region containing this field-aligned current is shaped more like a cylinder rather than a long sheet. The total current is found to exceed one-half million amperes. C1 UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. UNIV TEXAS,CTR SPACE SCI,RICHARDSON,TX 75083. MISSION RES CORP,NASHUA,NH. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WEIMER, DR (reprint author), UNIV ALASKA,INST GEOPHYS,BOX 757320,FAIRBANKS,AK 99775, USA. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 34 TC 34 Z9 34 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD DEC 1 PY 1994 VL 99 IS A12 BP 23639 EP 23649 DI 10.1029/94JA01976 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PV624 UT WOS:A1994PV62400040 ER PT J AU WHITTENBERGER, JD AF WHITTENBERGER, JD TI MECHANICAL-PROPERTIES OF HAYNES ALLOY-188 AFTER 22,500 HOURS OF EXPOSURE TO LIF-22CAF(2) AND VACUUM AT 1093 K SO JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE LA English DT Article DE HAYNES ALLOY 188; HEAT TREATMENT; LONG TERM EXPOSURE; MECHANICAL PROPERTIES; SUPERALLOY; THERMAL ENERGY STORAGE ID AIR AB As a continuation of a study of a space-based therm al energy storage system centered on a LiF-CaF2 eutectic salt contained by Haynes alloy 188, this Go-base superalloy was subjected to molten salt, its vapor, and vacuum for 22,500 h at 1093 K. Samples from all three exposure conditions were tensile tested between 77 to 1200 K; in addition, vacuum and molten-salt exposed specimens were vacuum creep rupture tested at 1050 K. Comparison of these mechanical properties with those measured for the as-received alloy reveals no evidence for degradation beyond that ascribed to simple thermal aging of Haynes alloy 188. This behavior is identical to the 10,000 h results (Ref 3); hence, Haynes alloy 188 is a suitable containment material for an eutectic LiF-CaF2 thermal energy storage salt. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 6 TC 7 Z9 8 U1 1 U2 2 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 1059-9495 J9 J MATER ENG PERFORM JI J. Mater. Eng. Perform. PD DEC PY 1994 VL 3 IS 6 BP 754 EP 762 DI 10.1007/BF02818376 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA QK818 UT WOS:A1994QK81800010 ER PT J AU WHITTENBERGER, JD AF WHITTENBERGER, JD TI TENSILE PROPERTIES OF HAYNES ALLOY-230 AND INCONEL-617 AFTER LONG EXPOSURES TO LIF-22CAF(2) AND VACUUM AT 1093 K SO JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE LA English DT Article DE INCONEL 617; HAYNES ALLOY 230; HEAT TREATMENT; LONG TERM EXPOSURE; SUPERALLOY; TENSILE PROPERTIES; THERMAL ENERGY STORAGE ID AIR AB As a part of a study of a space-based thermal energy storage system utilizing the latent heat of fusion of the eutectic salt LiF-20CaF(2) (mole %), the two wrought Ni-base superalloys Haynes alloy 230 and Inconel 617 were subjected to molten salt, its vapor, and vacuum for periods as long as 10,000 h at 1093 K, Following exposure, the microstructures were characterized, and samples from each superalloy were tensile tested between 77 and 1200 K. Neither the structure nor mechanical properties revealed evidence for additional degradation due to exposures to the salt, Although some loss in tensile properties was noted, particularly at 77 K, this reduction could be ascribed to the influence of simple aging at 1093 K. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP WHITTENBERGER, JD (reprint author), MAX PLANCK INST MET RES,STUTTGART,GERMANY. NR 15 TC 5 Z9 5 U1 1 U2 5 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 1059-9495 J9 J MATER ENG PERFORM JI J. Mater. Eng. Perform. PD DEC PY 1994 VL 3 IS 6 BP 763 EP 774 DI 10.1007/BF02818377 PG 12 WC Materials Science, Multidisciplinary SC Materials Science GA QK818 UT WOS:A1994QK81800011 ER PT J AU HOLLAND, FA ZARETSKY, EV AF HOLLAND, FA ZARETSKY, EV TI COMPARISON OF WEIBULL STRENGTH PARAMETERS FROM FLEXURE AND SPIN TESTS OF BRITTLE MATERIALS SO JOURNAL OF MECHANICAL DESIGN LA English DT Article AB Fracture data from five series of four-point bend tests of beams and spin tests of flat annular disks were reanalyzed. Silicon nitride and graphite were the test materials. The experimental fracture strengths of the disks were compared with the predicted strengths based on both volume flaw and surface flaw analyses of four-point bend data. Surface flaw analyses resulted in good correlation with experimental results in those test series where all tested specimens were obtained from the same material batch. The Weibull slopes (moduli) and characteristic gage strengths for the disks and beams were also compared. Differences in the experimental Weibull slopes were not statistically significant. it was shown that results from the beam tests can predict the fracture strength of rotating disks under well controlled conditions. RP HOLLAND, FA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 1050-0472 J9 J MECH DESIGN JI J. Mech. Des. PD DEC PY 1994 VL 116 IS 4 BP 973 EP 979 DI 10.1115/1.2919507 PG 7 WC Engineering, Mechanical SC Engineering GA QA506 UT WOS:A1994QA50600001 ER PT J AU TAHMASEBI, F TSAI, LW AF TAHMASEBI, F TSAI, LW TI CLOSED-FORM DIRECT KINEMATICS SOLUTION OF A NEW PARALLEL MINIMANIPULATOR SO JOURNAL OF MECHANICAL DESIGN LA English DT Article AB Closed-form direct kinematics solution of a new three-limbed six-degree-of-freedom minimanipulator is presented. Five-bar linkages and inextensible limbs are used in synthesis of the minimanipulator to improve its positional resolution and stiffness. AN of the minimanipulator actuators are base-mounted. Kinematic inversion is used to reduce the direct kinematics of the minimanipulator to an eighth-degree polynomial in the square of tangent of half-angle between one of the limbs and the moving platform. Hence, the maximum number of assembly configurations for the minimanipulator is sixteen. Furthermore, if is proved that the sixteen solutions are eight pairs of reflected configurations with respect to the plane passing through the lower ends of the three limbs. A numerical example is also presented and the results are verified by an inverse kinematics analysis. RP TAHMASEBI, F (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ROBOT BRANCH,GREENBELT,MD 20771, USA. NR 0 TC 24 Z9 24 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 1050-0472 J9 J MECH DESIGN JI J. Mech. Des. PD DEC PY 1994 VL 116 IS 4 BP 1141 EP 1147 DI 10.1115/1.2919498 PG 7 WC Engineering, Mechanical SC Engineering GA QA506 UT WOS:A1994QA50600023 ER PT J AU BROWN, LR PETERSON, DB AF BROWN, LR PETERSON, DB TI AN EMPIRICAL EXPRESSION FOR LINEWIDTHS OF AMMONIA FROM FAR-INFRARED MEASUREMENTS SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID LINE WIDTHS; NU(1) BAND; SPECTRUM; HYDROGEN; OZONE; NH3 AB The hydrogen- and self-broadened linewidths of 116 (NH3)-N-14 ground state transitions with J,K = 1,0 to 10,10 have been measured at 0.006-cm(-1) resolution between 40 and 210 cm(-1) using a Bruker spectrometer. These experimental widths have been reproduced to 2.4 and 11%, respectively, using a heuristically derived expression of the form gamma = a(0) + a(1)J'' + a(2)K'' + a(3)J''(2) + a(4)J''K'', where J'' and K'' are the lower state symmetric-top quantum numbers. This function has also been applied to the measured widths of the 58 transitions of nu(1), each broadened by N-2, O-2, Ar, H-2, He [Pine el al., J. Quant. Spectrosc. Radiat. Transfer 50, 337-348 (1993)], and NH3 [Markov el al., J. Quant. Spectrosc Radiat. Transfer 50, 167-178 (1993)]. The rms of the observed minus calculated widths are +/-5% or better for the five foreign broadeners. For the self-broadening case, the expression fails to reproduce the K = 0 data. The values of the fitted constants suggest that for some broadeners the expression might also be written as gamma = a(0) + b(1)J'' - a(2)(J'' - K'') + b(3)J''(J'' - K''). (C) 1994 Academic Press, Inc. RP BROWN, LR (reprint author), CALTECH,JET PROP LAB,MAIL STOP 183-301,PASADENA,CA 91109, USA. NR 18 TC 57 Z9 57 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD DEC PY 1994 VL 168 IS 2 BP 593 EP 606 DI 10.1006/jmsp.1994.1305 PG 14 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA PU608 UT WOS:A1994PU60800035 ER PT J AU KIM, SS WESTMORELAND, DG AF KIM, SS WESTMORELAND, DG TI EMULSION POLYMERIZATION OF BUTYL ACRYLATE - SPIN-TRAPPING AND EPR STUDY SO JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY LA English DT Article DE EMULSION POLYMERIZATION; BUTYL ACRYLATE; POLY(N-BUTYL ACRYLATE); ELECTRON PARAMAGNETIC RESONANCE; SPIN TRAPPING ID FREE-RADICAL CONCENTRATIONS; CONTINUOUS ESR MEASUREMENT; METHYL-METHACRYLATE; VINYL MONOMERS; RESONANCE; 2-METHYL-2-NITROSOPROPANE; PHOTOLYSIS AB The propagating radical in the emulsion polymerization reaction of butyl acrylate was detected by Electron Paramagnetic Resonance (EPR) spectroscopy using two spin-trapping agents, 2-methyl-2-nitrosopropane (MNP) and alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (PyOBN). Through analysis of hyperfine structure of the spectra obtained from the trapped radicals, the propagating radical is inferred to be the well known acrylate radical, -[CH2-CH(COOC4H9)](n)-CH2-CH(COOC4H9)-. (C) 1994 John Wiley and Sons, Inc. C1 ROHM & HAAS CO,RES LABS,SPRING HOUSE,PA 19477. RP KIM, SS (reprint author), CALTECH,SPACE MAT SCI & ENGN SECT,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 31 TC 6 Z9 6 U1 5 U2 5 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-624X J9 J POLYM SCI POL CHEM JI J. Polym. Sci. Pol. Chem. PD DEC PY 1994 VL 32 IS 16 BP 3031 EP 3037 DI 10.1002/pola.1994.080321604 PG 7 WC Polymer Science SC Polymer Science GA PU612 UT WOS:A1994PU61200004 ER PT J AU HERGENROTHER, PM BRYANT, RG JENSEN, BJ HAVENS, SJ AF HERGENROTHER, PM BRYANT, RG JENSEN, BJ HAVENS, SJ TI PHENYLETHYNYL-TERMINATED IMIDE OLIGOMERS AND POLYMERS THEREFROM SO JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY LA English DT Article DE OLIGOMERS; PHENYLETHYNYL TERMINATION; THERMALLY STABLE POLYMERS; POLYIMIDES; HIGH-PERFORMANCE POLYMERS; FILMS AB Two new phenylethynyl endcapping compounds, 3- and 4-amino-4'-phenylethynylbenzophenone, were synthesized and used to terminate imide oligomers from 3,4'-oxydianiline and 4,4'-oxydiphthalic anhydride at a calculated molecular weight of 9000 g/mol and from 3,4'-oxydianiline (0.85 mol), 1,3-bis( 3-aminophenoxy)benzene (0.15 mol), and 3,3',4,4'-biphenyltetracarboxylic dianhydride at a calculated molecular weight of 5000 g/mol. Glass transition temperatures for the cured oligomers were similar to 249 degrees C for the former and similar to 272 degrees C for the latter. Films cured at 350 degrees C for 1 h were tough and flexible and provided high tensile properties. The uncured oligomers were readily compression molded to provide tough, solvent-resistant moldings. (C) 1994 John Wiley and Sons, Inc. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23681. RP HERGENROTHER, PM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 15 TC 62 Z9 65 U1 0 U2 10 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-624X J9 J POLYM SCI POL CHEM JI J. Polym. Sci. Pol. Chem. PD DEC PY 1994 VL 32 IS 16 BP 3061 EP 3067 DI 10.1002/pola.1994.080321607 PG 7 WC Polymer Science SC Polymer Science GA PU612 UT WOS:A1994PU61200007 ER PT J AU VAIDYANATHAN, H RAO, GM AF VAIDYANATHAN, H RAO, GM TI REACTIONS DURING REVERSAL OF AN NI H-2 CELL SO JOURNAL OF POWER SOURCES LA English DT Article DE NICKEL HYDROGEN CELLS; REVERSAL REACTIONS ID OXIDE FILM THICKNESS; ELECTRODES; MECHANISM; BATTERY AB The chemical reactions that occur during reversal of aerospace-design nickel-hydrogen (Ni-H-2) cells are examined by determining voltage changes and heat dissipation. Radiative calorimetry is used to measure the rate of heat dissipation during charge, discharge, and reversal. The heat dissipated during reversal at C/10 rate (8.1 A) for a positive precharge cell is four times greater than that for a hydrogen precharge cell. For a cell design with a positive precharge, the reversal reactions consist of completion of nickel electrode discharge and hydrogen evolution on the nickel (positive) electrode, platinum oxide/hydroxide formation, and subsequent reduction by hydrogen at the hydrogen (negative) electrode. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP VAIDYANATHAN, H (reprint author), COMSAT LABS,CLARKSBURG,MD 20871, USA. NR 11 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD DEC PY 1994 VL 52 IS 2 BP 223 EP 229 DI 10.1016/0378-7753(94)02011-6 PG 7 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA QD431 UT WOS:A1994QD43100010 ER PT J AU HERRING, GC SOUTH, BW AF HERRING, GC SOUTH, BW TI PRESSURE BROADENING OF VIBRATIONAL RAMAN LINES IN N-2 AT TEMPERATURES BELOW 300-K SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID SPECTROSCOPY; SPECTRA; CO AB Using quasi-cw stimulated Raman gain spectroscopy, the pressure broadening coefficients for the N-2 vibrational Q-branch transitions have been measured over the temperature range 113-297 K for the rotational components J = 4, 6, 8, 10, and 12. The experimental results are fit to a simple power law to give an empirical formula for the temperature dependence of the pressure broadening over the 100-300 K range. These results are also compared to previously published scaling laws that are based on collision induced rotational transition rates. RP HERRING, GC (reprint author), NASA,LANGLEY RES CTR,DIV INSTRUMENT RES,HAMPTON,VA 23681, USA. NR 19 TC 15 Z9 15 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 DEC PY 1994 VL 52 IS 6 BP 835 EP 840 DI 10.1016/0022-4073(94)90049-3 PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA QE660 UT WOS:A1994QE66000014 ER PT J AU COLBAUGH, R SERAJI, H GLASS, K AF COLBAUGH, R SERAJI, H GLASS, K TI A NEW CLASS OF ADAPTIVE CONTROLLERS FOR ROBOT TRAJECTORY TRACKING SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article ID REDUNDANT MANIPULATORS; CONFIGURATION CONTROL; CONTROL LAWS; SYSTEMS; ROBUSTNESS AB This article presents a new class of adaptive schemes for the motion control of robot manipulators. The proposed controllers are very general and computationally efficient because they do not require knowledge of either the mathematical model or the parameter values of the manipulator dynamics, and are implemented without calculation of the robot inverse dynamics or inverse kinematic transformations. It is shown that the control strategies are globally uniformly bounded in the presence of bounded disturbances, and that in the absence of disturbances the ultimate bound on the size of the tracking errors can be made arbitrarily small. Computer simulation results are given for a PUMA 560 manipulator, and demonstrate that accurate and robust trajectory tracking can be achieved by using the proposed controllers. (C) 1994 John Wiley & Sons, Inc. C1 NEW MEXICO STATE UNIV, DEPT MECH ENGN, LAS CRUCES, NM 88003 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP GLASS, K (reprint author), NEW MEXICO STATE UNIV, DEPT MECH ENGN, LAS CRUCES, NM 88003 USA. NR 29 TC 9 Z9 9 U1 0 U2 1 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 DEC PY 1994 VL 11 IS 8 BP 761 EP 772 DI 10.1002/rob.4620110808 PG 12 WC Robotics SC Robotics GA QM207 UT WOS:A1994QM20700007 ER PT J AU BARNES, NP MURRAY, KE JANI, MG HARRELL, SR AF BARNES, NP MURRAY, KE JANI, MG HARRELL, SR TI DIODE-PUMPED HO-TM-YLF LASER PUMPING AN AGGASE2 PARAMETRIC OSCILLATOR SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article AB Tuning of both the pump laser, a Ho:Tm:YLF laser operating on the I-5(7)-I-5(8) transition, and an AgGaSe2 parametric oscillator has been demonstrated. Tuning of the Ho:Tm:YLF laser is complicated but not frustrated by the existence of both CO2 and H2O lines in the vicinity of the laser transition. Tuning of the parametric oscillator was achieved by tuning of the pump laser. Injection seeding of the parametric oscillator on the nonresonant signal was also demonstrated. In addition, the measured efficiencies of the parametric oscillator were compared for two different methods, measuring the parametric-oscillator output energy and measuring the energy depleted from the pump. By comparison of these measurements, the intrinsic efficiency of the parametric oscillator can be determined. C1 SCI & TECHNOL CORP,HAMPTON,VA 23666. UNIV S FLORIDA,TAMPA,FL 33620. RP BARNES, NP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 13 TC 12 Z9 12 U1 0 U2 0 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 DEC PY 1994 VL 11 IS 12 BP 2422 EP 2426 DI 10.1364/JOSAB.11.002422 PG 5 WC Optics SC Optics GA PX510 UT WOS:A1994PX51000013 ER PT J AU HARPER, JS MULENBURG, GM EVANS, J NAVIDI, M WOLINSKY, I ARNAUD, SB AF HARPER, JS MULENBURG, GM EVANS, J NAVIDI, M WOLINSKY, I ARNAUD, SB TI METABOLIC CAGES FOR A SPACE-FLIGHT MODEL IN THE RAT SO LABORATORY ANIMAL SCIENCE LA English DT Note ID SIMULATED WEIGHTLESSNESS; CALCIUM BALANCE; HYPOKINESIA; ATROPHY; MUSCLE C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. UNIV HOUSTON,HOUSTON,TX 77204. NR 15 TC 21 Z9 21 U1 0 U2 0 PU AMER ASSOC LABORATORY ANIMAL SCIENCE PI CORDOVA PA 70 TIMBERCREEK DR, SUITE 5, CORDOVA, TN 38018 SN 0023-6764 J9 LAB ANIM SCI JI Lab. Anim. Sci. PD DEC PY 1994 VL 44 IS 6 BP 645 EP 647 PG 3 WC Veterinary Sciences; Zoology SC Veterinary Sciences; Zoology GA QB522 UT WOS:A1994QB52200021 PM 7898043 ER PT J AU STEIMLE, FW ZDANOWICZ, VS CUNNEFF, SL TERRANOVA, R AF STEIMLE, FW ZDANOWICZ, VS CUNNEFF, SL TERRANOVA, R TI TRACE-METAL CONCENTRATIONS IN COMMON BENTHIC MACROFAUNAL PREY FROM THE NEW-YORK BIGHT APEX SO MARINE POLLUTION BULLETIN LA English DT Note ID ACCUMULATION; SEDIMENTS; PHYTOPLANKTON; INVERTEBRATES; ECOSYSTEMS; MERCURY; CADMIUM; FOOD RP US DEPT COMMERCE, NOAA, NATL MARINE FISHERIES SERV, NE FISHERIES SCI CTR, HIGHLANDS, NJ 07732 USA. NR 37 TC 5 Z9 5 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0025-326X EI 1879-3363 J9 MAR POLLUT BULL JI Mar. Pollut. Bull. PD DEC PY 1994 VL 28 IS 12 BP 760 EP 765 DI 10.1016/0025-326X(94)90336-0 PG 6 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA QE610 UT WOS:A1994QE61000009 ER PT J AU FAUR, M FAUR, M FLOOD, DJ GORADIA, M AF FAUR, M FAUR, M FLOOD, DJ GORADIA, M TI ELECTROLYTE FOR ELECTROCHEMICAL C-V PROFILING OF INP-BASED AND GAAS-BASED STRUCTURES SO MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY LA English DT Article; Proceedings Paper CT 2nd International Workshop on Expert Evaluation and Control of Compound Semiconductor Materials and Technologies (EXMATEC 94) CY MAY 18-20, 1994 CL PARMA, ITALY DE SEMICONDUCTOR ELECTROLYTE; ETCHING AB A new electrolyte (UNIEL) based on HF, NH3F2, C9H14CIN, CH3COOH and o-H3PO4 has been developed for accurate EC-V net majority carrier concentration profiling of InP- and GaAs-based III-V semiconductors. The new electrolyte was tested with good results on heterostructures containing p- and n-type InP, GaAs,InGaAs and InGaAsP layers. C1 CLEVELAND STATE UNIV, CLEVELAND, OH 44115 USA. RP FAUR, M (reprint author), NASA, LEWIS RES CTR, MS 302-1, 21000 BROOKPARK RD, CLEVELAND, OH 44135 USA. NR 7 TC 5 Z9 5 U1 1 U2 1 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5107 J9 MAT SCI ENG B-SOLID JI Mater. Sci. Eng. B-Solid State Mater. Adv. Technol. PD DEC PY 1994 VL 28 IS 1-3 BP 361 EP 364 DI 10.1016/0921-5107(94)90083-3 PG 4 WC Materials Science, Multidisciplinary; Physics, Condensed Matter SC Materials Science; Physics GA PZ355 UT WOS:A1994PZ35500081 ER PT J AU HARRIS, BA AF HARRIS, BA TI TELEMEDICINE - A GLANCE INTO THE FUTURE SO MAYO CLINIC PROCEEDINGS LA English DT Editorial Material ID HEALTH-CARE RP HARRIS, BA (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,MAIL CODE CB,2101 NASA RD 1,HOUSTON,TX 77058, USA. NR 15 TC 15 Z9 16 U1 1 U2 1 PU MAYO CLINIC PROCEEDINGS PI ROCHESTER PA 660 SIEBENS BLDG MAYO CLINIC, ROCHESTER, MN 55905 SN 0025-6196 J9 MAYO CLIN PROC JI Mayo Clin. Proc. PD DEC PY 1994 VL 69 IS 12 BP 1212 EP 1214 PG 3 WC Medicine, General & Internal SC General & Internal Medicine GA PV968 UT WOS:A1994PV96800015 PM 7967785 ER PT J AU TENNANT, AF BAILEY, J WICKRAMASINGHE, DT WU, KW FERRARIO, L HOUGH, J AF TENNANT, AF BAILEY, J WICKRAMASINGHE, DT WU, KW FERRARIO, L HOUGH, J TI WW HOROLOGII - X-RAY AND OPTICAL OBSERVATIONS SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE BINARIES, CLOSE; STARS, INDIVIDUAL, WW HOR; STARS, MAGNETIC FIELDS; NOVAE, CATACLYSMIC VARIABLES; X-RAYS, STARS ID AM HERCULIS BINARIES AB The eclipsing AM Herculis binary WW Hor (EXO 023432-5232.3) was observed in the X-ray band with the ROSAT satellite and in the optical band with the 3.9-m telescope of the Anglo-Australian Observatory. A clear eclipse is seen in the X-ray light curve of this system for the first time. The relative location of the X-ray eclipse suggests that the accretion pole on the white dwarf surface has migrated in the last few years, consistent with the optical data. The 0.2-2 keV spectrum is well fitted with an absorbed power-law model. There is no indication of a soft blackbody component, although such a component could be masked by the absorption. The X-ray luminosity of the system in the 0.2-2 keV band is 1.0 x 10(31) erg s(-1). C1 ANGLO AUSTRALIAN OBSERV,EPPING,NSW 2121,AUSTRALIA. AUSTRALIAN NATL UNIV,DEPT MATH,CANBERRA,ACT 0200,AUSTRALIA. UNIV SYDNEY,SCH PHYS,THEORET ASTROPHYS RES CTR,SYDNEY,NSW 2006,AUSTRALIA. HATFIELD POLYTECH,DIV PHYS SCI,HATFIELD AL10 9AB,HERTS,ENGLAND. RP TENNANT, AF (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-65,HUNTSVILLE,AL 35812, USA. NR 20 TC 3 Z9 3 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD DEC 1 PY 1994 VL 271 IS 3 BP 733 EP 736 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PU957 UT WOS:A1994PU95700023 ER PT J AU MCNIDER, RT SONG, AJ CASEY, DM WETZEL, PJ CROSSON, WL RABIN, RM AF MCNIDER, RT SONG, AJ CASEY, DM WETZEL, PJ CROSSON, WL RABIN, RM TI TOWARD A DYNAMIC-THERMODYNAMIC ASSIMILATION OF SATELLITE SURFACE-TEMPERATURE IN NUMERICAL ATMOSPHERIC MODELS SO MONTHLY WEATHER REVIEW LA English DT Article AB An assimilation technique is described in which satellite-observed surface skin temperature tendencies are used in a model surface energy budget so that the predicted rate of temperature change in the model more closely agrees with the satellite observations. Both visible and infrared GOES satellite data are used in the assimilation. The technique is based on analytically recovering surface moisture from similarity expressions derived from an evapotranspiration residual obtained as a difference between the unadjusted model evapotranspiration and the satellite-inferred evapotranspiration. The technique has application in regional-scale models where surface parameters such as root zone moisture, soil moisture, etc., are unknown. It is assumed that the largest error in the surface energy budget is in the evapotranspiration term. Two tests are given for the technique, first, a one-dimensional test against FIFE data and, second, a three-dimensional test over Oklahoma. In these cases the technique appears to correctly adjust the model response to agree better with observations. C1 UNIV ALABAMA,DEPT MATH SCI,HUNTSVILLE,AL 35899. UNIV ALABAMA,ATMOSPHER SCI PROGRAM,HUNTSVILLE,AL 35899. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,INST GLOBAL CHANGE RES & EDUC,HUNTSVILLE,AL 35812. NOAA,ENVIRONM RES LAB,NATL SEVERE STORMS LAB,NORMAN,OK 73069. RP MCNIDER, RT (reprint author), UNIV ALABAMA,EARTH SYST SCI LAB,HUNTSVILLE,AL 35899, USA. NR 8 TC 59 Z9 61 U1 1 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD DEC PY 1994 VL 122 IS 12 BP 2784 EP 2787 DI 10.1175/1520-0493(1994)122<2784:TADTAO>2.0.CO;2 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PW058 UT WOS:A1994PW05800010 ER PT J AU COHN, SE SIVAKUMARAN, NS TODLING, R AF COHN, SE SIVAKUMARAN, NS TODLING, R TI A FIXED-LAG KALMAN SMOOTHER FOR RETROSPECTIVE DATA ASSIMILATION SO MONTHLY WEATHER REVIEW LA English DT Article ID ATMOSPHERIC DATA ASSIMILATION; SATELLITE SOUNDING RADIANCES; NONLINEAR OPTIMAL ESTIMATION; FORECAST ERROR COVARIANCES; GEOSTROPHIC OCEAN MODEL; METEOROLOGICAL OBSERVATIONS; VARIATIONAL ASSIMILATION; FILTER; INVERSION; TOVS AB Data assimilation has traditionally been employed to provide initial conditions for numerical weather prediction (NWP). A multiyear time sequence of objective analyses produced by data assimilation can also be used as an archival record from which to carry out a variety of atmospheric process studies. For this latter purpose, NWP analyses are not as accurate as they could be, for each analysis is based only on current and past observed data, and not on any future data. Analyses incorporating future data, as well as current and past data, are termed retrospective analyses. The problem of retrospective objective analysis has not yet received attention in the meteorological literature. In this paper, the fixed-lag Kalman smoother (FLKS) is proposed as a means of providing retrospective analysis capability in data assimilation. The FLKS is a direct generalization of the Kalman filter. It incorporates all data observed up to and including some fixed amount of time past each analysis time. A computationally efficient form of the FLKS is derived. A simple scalar examination of the FLKS demonstrates that incorporating future data improves analyses the most in the presence of dynamical instabilities, for accurate models and for accurate observations. An implementation of the FLKS for a two-dimensional linear shallow-water model corroborates the scalar analysis. The numerical experiments also demonstrate the ability of the FLKS to propagate information upstream as well as downstream, thus improving analysis quality substantially in data voids. RP COHN, SE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DATA ASSIMILAT OFF,CODE 9103,GREENBELT,MD 20771, USA. RI Cohn, Stephen/K-1954-2012 OI Cohn, Stephen/0000-0001-8506-9354 NR 44 TC 75 Z9 75 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD DEC PY 1994 VL 122 IS 12 BP 2838 EP 2867 DI 10.1175/1520-0493(1994)122<2838:AFLKSF>2.0.CO;2 PG 30 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PW058 UT WOS:A1994PW05800014 ER PT J AU WEISSMAN, P AF WEISSMAN, P TI COMET SHOEMAKER-LEVY-9 - EVENTS AFTER THE EVENTS SO NATURE LA English DT Editorial Material RP WEISSMAN, P (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. NR 4 TC 3 Z9 3 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 DEC 1 PY 1994 VL 372 IS 6505 BP 404 EP 405 DI 10.1038/372404a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PV012 UT WOS:A1994PV01200028 ER PT J AU BEKEY, I AF BEKEY, I TI SSTO ROCKETS - A PRACTICAL POSSIBILITY SO NOUVELLE REVUE AERONAUTIQUE ASTRONAUTIQUE LA French DT Article AB Ever since rocket pioneers made their earliest calculations, they have recognized that the ultimate Earth-to-orbit launch vehicle would consist of only a single stage, one that discards only propellants. Ideally, the vehicle would be all propellant, and its structure, tanks, and subsystems would weigh almost nothing, minimizing its gross weight, size, and cost In a singlestage vehicle each pound of structure trades off for a pound of payload, so minimizing vehicle dry weight is critical. To this day, the classical solution is staging, which reduces the weight and performance required of each element but also introduces undesirable operational complexities and cost Most experts agree that SSTO rockets would become feasible if more advanced technologies were available to reduce the vehicle dry weight, increase propulsion system performance, or both. However, those technologies are usually judged very ambitious and very far off. Even if attained, say critics, the resulting vehicle would probably be extremely sensitive to weight growth, and thus would be impractical. For these reasons all past proposals for single-stage rockets were rejected. A common perception has developed that SSTO may be theoretically possible, but is neither feasible nor practical in the near future. This notion persists despite major advances in technology and vehicle design in the past decade. Because there are widely held misconceptions regarding the impact of these technologies, the present potential for a near-term SSTO rocket is wiewed with a great deal of skepticism. There appear to be four major perceptions about SSTOs: They require a very large mass fraction, which is infeasible or impractical to attain; they have little or no performance margin and can just barely make it into orbit, if at all: they can launch only small payloads that are a minuscule fraction of their weight; and they are extremely sensitive, so that even slight weight growth rapidly eats up all their payload capability. These perceptions can be dispelled for SSTO rockets using advanced technologies that could be matured and demonstrated in the near term, based on design analyses performed in support of NASA's recent ''Access to Space'' study. RP BEKEY, I (reprint author), NASA,OFF SPACE SYST DEV,WASHINGTON,DC 20546, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU DUNOD PI MONTROUGE CEDEX PA 15 RUE GOSSIN, 92543 MONTROUGE CEDEX, FRANCE SN 1247-5793 J9 NOUV REV AERONAUT AS JI Nouv. Rev. Aeronaut. Astronaut. PD DEC PY 1994 IS 4 BP 37 EP 42 PG 6 WC Engineering, Aerospace SC Engineering GA QE386 UT WOS:A1994QE38600005 ER PT J AU STICKLAND, DJ CORCORAN, MF AF STICKLAND, DJ CORCORAN, MF TI SPECTROSCOPIC BINARY ORBITS FROM ULTRAVIOLET RADIAL-VELOCITIES SO OBSERVATORY LA English DT Article ID EM-CARINAE C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP STICKLAND, DJ (reprint author), RUTHERFORD APPLETON LAB,DIDCOT OX11 0QX,OXON,ENGLAND. NR 10 TC 6 Z9 6 U1 0 U2 0 PU OBSERVATORY PI OXFORDSHIRE PA RUTHERFORD APPLETON LAB, CHILTON DIDCOT, OXFORDSHIRE, ENGLAND OX11 OQX SN 0029-7704 J9 OBSERVATORY JI Observatory PD DEC PY 1994 VL 114 IS 1123 BP 284 EP 287 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PY975 UT WOS:A1994PY97500003 ER PT J AU FLOOD, DJ WEINBERG, I AF FLOOD, DJ WEINBERG, I TI ADVANCED SOLAR-CELLS FOR SATELLITE POWER-SYSTEMS SO OPTOELECTRONICS-DEVICES AND TECHNOLOGIES LA English DT Article DE SPACE SOLAR CELLS; GAAS; SI; INP; MULTIPLE BANDGAP CELLS; THIN FILM CELLS; RADIATION DAMAGE ID INP AB The multiple natures of today's space missions with regard to operational lifetime, orbital environment, cost and size of spacecraft, to name just a few, present such a broad range of performance requirements to be met by the solar array that no single design can suffice to meet them all. The result is a demand for development of specialized solar cell types that help to optimize overall satellite performance within a specified cost range for any given space mission. Historically, space solar array performance has been optimized for a given mission by tailoring the features of silicon solar cells to account for the orbital environment and average operating conditions expected during the mission. It has become necessary to turn to entirely new photovoltaic materials and device designs to meet the requirements of future missions, both in the near and far term. This paper will outline some of the mission drivers and resulting performance requirements that must be met by advanced solar cells, and provide an overview of some of the advanced cell technologies under development to meet them. The discussion will include high efficiency, radiation hard single junction cells; monolithic and mechanically stacked multiple bandgap cells; and thin film cells. RP FLOOD, DJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 26 TC 3 Z9 3 U1 0 U2 2 PU MITA PRESS PI TOKYO PA OCHANOMIZU CENTER BLDG 2-12 HONGO-3 BUNKYO-KU, TOKYO 113, JAPAN SN 0912-5434 J9 OPTOELECTRON-DEVICES JI Optoelectron.-Devices Technol. PD DEC PY 1994 VL 9 IS 4 BP 451 EP 458 PG 8 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA QD449 UT WOS:A1994QD44900003 ER PT J AU WALLACE, TA CLARK, RK WIEDEMANN, KE AF WALLACE, TA CLARK, RK WIEDEMANN, KE TI OXIDATION OF TI-14AL-21NB IN AIR AND OXYGEN FROM 700-DEGREES-C TO 1000-DEGREES-C SO OXIDATION OF METALS LA English DT Article DE OXIDATION; TITANIUM ALUMINIDE; AIR; OXYGEN ID TITANIUM AB The oxidation behavior of Ti-14Al-21Nb in air and in oxygen was determined over the temperature range 700 to 1000 degrees C. Weight gains in both atmospheres were measured using thermogravimetric analysis. The resulting oxidation products were identified using X-ray diffraction, and oxide morphology was evaluated using electron microscopy and wavelength-dispersive X-fay analysis. Total weight gains in oxygen were up to four times higher than in air, and a higher percentage of the weight gain in oxygen was due to oxygen dissolution into the metal. Based on metallurgical examination of the oxidized specimens, it was concluded that the lower oxidation weight gains in air are due to the formation of a thin layer of TiN and TiAl at the oxide-metal interface which inhibits the diffusion of oxygen into the metal. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. RP WALLACE, TA (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 188A,HAMPTON,VA 23681, USA. NR 8 TC 18 Z9 19 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0030-770X J9 OXID MET JI Oxid. Met. PD DEC PY 1994 VL 42 IS 5-6 BP 451 EP 464 PG 14 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA PZ236 UT WOS:A1994PZ23600007 ER PT J AU DUBEY, A ZUBAIR, M GROSCH, CE AF DUBEY, A ZUBAIR, M GROSCH, CE TI A GENERAL-PURPOSE SUBROUTINE FOR FAST FOURIER-TRANSFORM ON A DISTRIBUTED-MEMORY PARALLEL MACHINE SO PARALLEL COMPUTING LA English DT Article DE FAST FOURIER TRANSFORM; DISTRIBUTED MEMORY PARALLEL MACHINE; DATA DISTRIBUTION; IMPLEMENTATION FEATURES; PERFORMANCE RESULTS; INTEL IPSC/860 ID FFT; MULTIPROCESSOR; HYPERCUBE AB One issue which is central in developing a general purpose FFT subroutine on a distributed memory parallel machine is the data distribution. It is possible that different users would like to use the FFT routine with different data distributions. Thus there is a need to design FFT schemes on distributed memory parallel machines which can support a variety of data distributions. In this paper we present an FFT implementation on a distributed memory parallel machine which works for a number of data distributions commonly encountered in scientific applications. We have also addressed the problem of rearranging the data after computing the FFT. We have evaluated the performance of our implementation on a distributed memory parallel machine, the Intel iPSC/860. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. RP DUBEY, A (reprint author), OLD DOMINION UNIV,DEPT COMP SCI,NORFOLK,VA 23529, USA. NR 23 TC 5 Z9 5 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-8191 J9 PARALLEL COMPUT JI Parallel Comput. PD DEC PY 1994 VL 20 IS 12 BP 1697 EP 1710 DI 10.1016/0167-8191(94)90126-0 PG 14 WC Computer Science, Theory & Methods SC Computer Science GA QB203 UT WOS:A1994QB20300001 ER PT J AU BHATIA, AK HO, YK AF BHATIA, AK HO, YK TI D-3(0) SHAPE-RESONANT STATE OF H- LYING ABOVE THE HYDROGEN N=3 THRESHOLD SO PHYSICAL REVIEW A LA English DT Article ID DOUBLY EXCITED-STATES; 2-ELECTRON ATOMS; PHOTODETACHMENT; ELECTRON; MATRIX C1 ACAD SINICA,INST ATOM & MOLEC SCI,TAIPEI,TAIWAN. RP BHATIA, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Ho, Yew Kam/F-7912-2012 NR 28 TC 15 Z9 15 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD DEC PY 1994 VL 50 IS 6 BP 4886 EP 4890 DI 10.1103/PhysRevA.50.4886 PN A PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PX179 UT WOS:A1994PX17900051 ER PT J AU MASAD, JA ZURIGAT, YH AF MASAD, JA ZURIGAT, YH TI EFFECT OF PRESSURE-GRADIENT ON FIRST MODE OF INSTABILITY IN COMPRESSIBLE BOUNDARY-LAYERS SO PHYSICS OF FLUIDS LA English DT Article ID STABILITY C1 UNIV JORDAN,DEPT MECH ENGN,AMMAN,JORDAN. NASA,LANGLEY RES CTR,INST COMP APPL SCI & ENGN,HAMPTON,VA 23681. RP MASAD, JA (reprint author), HIGH TECHNOL CORP,HAMPTON,VA 23666, USA. NR 27 TC 0 Z9 0 U1 1 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD DEC PY 1994 VL 6 IS 12 BP 3945 EP 3953 DI 10.1063/1.868384 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PW984 UT WOS:A1994PW98400016 ER PT J AU RAMAN, G RICE, EJ AF RAMAN, G RICE, EJ TI INSTABILITY MODES EXCITED BY NATURAL SCREECH TONES IN A SUPERSONIC RECTANGULAR JET SO PHYSICS OF FLUIDS LA English DT Article ID LARGE-SCALE STRUCTURES; NOISE; FIELD; SOUND; FLOW C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP RAMAN, G (reprint author), NASA,NYMA INC,LEWIS RES CTR GRP,EXPTL FLUID DYNAM SECT,CLEVELAND,OH 44135, USA. NR 34 TC 36 Z9 36 U1 2 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD DEC PY 1994 VL 6 IS 12 BP 3999 EP 4008 DI 10.1063/1.868389 PG 10 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PW984 UT WOS:A1994PW98400021 ER PT J AU PEARLMAN, HG RONNEY, PD AF PEARLMAN, HG RONNEY, PD TI NEAR-LIMIT BEHAVIOR OF HIGH-LEWIS NUMBER PREMIXED FLAMES IN TUBES AT NORMAL AND LOW GRAVITY SO PHYSICS OF FLUIDS LA English DT Article ID PROPAGATION; STABILITY C1 UNIV SO CALIF,DEPT MECH ENGN,LOS ANGELES,CA 90089. RP PEARLMAN, HG (reprint author), NASA,LEWIS RES CTR,MAIL STOP 500-115,CLEVELAND,OH 44135, USA. RI Ronney, Paul/B-4007-2009 OI Ronney, Paul/0000-0002-2779-6438 NR 28 TC 42 Z9 44 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD DEC PY 1994 VL 6 IS 12 BP 4009 EP 4018 DI 10.1063/1.868390 PG 10 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PW984 UT WOS:A1994PW98400022 ER PT J AU GUNAPALA, S SARUSI, G PARK, J LIN, TL LEVINE, B AF GUNAPALA, S SARUSI, G PARK, J LIN, TL LEVINE, B TI INFRARED DETECTORS REACH NEW LENGTHS SO PHYSICS WORLD LA English DT Article RP GUNAPALA, S (reprint author), JET PROP LAB,CTR SPACE MICROELECTR,PASADENA,CA 91109, USA. NR 0 TC 17 Z9 17 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-8585 J9 PHYS WORLD JI Phys. World PD DEC PY 1994 VL 7 IS 12 BP 35 EP 40 PG 6 WC Physics, Multidisciplinary SC Physics GA PY042 UT WOS:A1994PY04200028 ER PT J AU BENZ, W ASPHAUG, E RYAN, EV AF BENZ, W ASPHAUG, E RYAN, EV TI NUMERICAL SIMULATIONS OF CATASTROPHIC DISRUPTION - RECENT RESULTS SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Workshop on Catastrophic Disruption of Small Solar System Bodies CY JUN, 1993 CL GUBBIO, ITALY ID COLLISIONAL DISRUPTION; SCALING LAWS; IMPACT; FRAGMENTATION; ASTEROIDS; METEORITES; VESTA AB Numerical simulations have been used to study high velocity two-body impacts. In this paper a two-dimensional Lagrangian finite difference hydrocode and a three-dimensional smooth particle hydrocode (SPH) are described and initial results reported. The 2D hydrocode has successfully reproduced both the fragment size distribution and the mean fragment velocities from laboratory impact experiments using basalt and cement mortar. Further, the hydrocode calculations have determined that the energy needed to fracture a body has a much stronger dependence on target size than predicted from most scaling theories. In addition, velocity distributions obtained (using homogeneous targets at impact velocities around 2 km s(-1)) indicate that mean ejecta speeds resulting from large-body collisions do not generally exceed escape velocities. The SPH model provides a fully three-dimensional framework for studying impacts, so that phenomena such as oblique collisions or impacts into non-spherical targets may be studied. The gridless code allows for arbitrary levels of distortion, and is hence appropriate for modeling the large-scale deformations which accompany most impact events. Because fragments are modeled explicitly, greater numerical accuracy is achieved in the regions of large fragments than with the purely statistical approach of the 2D model. Of course, this accuracy comes at the expense of significantly greater computational requirements. These codes can be, and have been, used to make specific predictions about particular objects in our solar system. But more significantly, they allow us to explore a broad range of collisional events. Certain parameters (size, time) can be studied only over a very restricted range within the laboratory; other parameters (initial spin, low gravity, exotic structure or composition) are difficult to study at all experimentally. The outcomes of numerical simulations lead to a more general and accurate understanding of impacts in their many forms. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035. INST PLANT SCI,TUCSON,AZ 85705. RP BENZ, W (reprint author), UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721, USA. NR 32 TC 18 Z9 18 U1 0 U2 0 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 DEC PY 1994 VL 42 IS 12 BP 1053 EP 1066 DI 10.1016/0032-0633(94)90006-X PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QT405 UT WOS:A1994QT40500006 ER PT J AU ZEBKER, HA FARR, TG SALAZAR, RP DIXON, TH AF ZEBKER, HA FARR, TG SALAZAR, RP DIXON, TH TI MAPPING THE WORLDS TOPOGRAPHY USING RADAR INTERFEROMETRY - THE TOPSAT MISSION SO PROCEEDINGS OF THE IEEE LA English DT Article ID SYNTHETIC APERTURE RADARS AB Global-scale topographic data are of fundamental importance to many Earth science studies, and obtaining these data is a priority for the Earth science community. Several groups have considered the requirements for such a data set, and a consensus assessment is that many critical studies would be enabled by the availability of a digital global topographic model with accuracies of 2 and 30 m in the vertical and horizontal directions, respectively. Radar interferometer techniques have been used to produce digital elevation models at these accuracies and are technologically feasible as the centerpiece of a spaceborne satellite mission designed to map the world's land masses, which we denote TOPSAT. A radar interferometer is formed by combining the radar echoes received at a pair of antennas displaced across-track, and specialized data processing results in the elevation data. Two alternative implementations, one ruing a 2 cm-lambda radar, and one using a 24 cm-lambda radar, ale technologically feasible. The former requires an interferometer baseline length of about 15 m to achieve the required accuracy, and thus could be built on a single spacecraft with a long extendable boom. The latter necessitates a kilometers-long baseline, and would thus be best implemented using two spacecrafting information. Measurement errors are dominated by phase noise, due largely to signal-to-noise ratio considerations, and attitude errors in determining the baseline orientation. For the 2-m accuracy required by TOPSAT, the orientation must be known to I are-second For the single-spacecraft approach, where attitude would be determined by sta, tracking systems, this performance is just beyond the several are-second range of existing instruments. For the dual-spacecraft systems, though, differential global positioning satellite measurements possess sufficient accuracy. Studies indicate that similar performance can be realized with either system. C1 UNIV MIAMI, ROSENSTIEL SCH MARINE & ATMOSPHER SCI, MIAMI, FL 33149 USA. RP ZEBKER, HA (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. OI Farr, Thomas/0000-0001-5406-2096 NR 24 TC 53 Z9 54 U1 0 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9219 J9 P IEEE JI Proc. IEEE PD DEC PY 1994 VL 82 IS 12 BP 1774 EP 1786 DI 10.1109/5.338070 PG 13 WC Engineering, Electrical & Electronic SC Engineering GA PW156 UT WOS:A1994PW15600002 ER PT J AU LEVINE, DM GRIFFIS, AJ SWIFT, CT JACKSON, TJ AF LEVINE, DM GRIFFIS, AJ SWIFT, CT JACKSON, TJ TI ESTAR - A SYNTHETIC-APERTURE MICROWAVE RADIOMETER FOR REMOTE-SENSING APPLICATIONS SO PROCEEDINGS OF THE IEEE LA English DT Article ID SOIL-MOISTURE; ENVIRONMENT; SALINITY; FIFE AB ESTAR represents a new technology being developed for passive microwave I-emote sensing of the environment from space. The instrument employs an interferometric ic technique called aperture synthesis in which the coherent product from pails of antennas is measured as a function of pair spacing. Substantial reductions in the antenna aperture needed for a given spatial resolution can be achieved with this technique. As a result, aperture synthesis could lead to practical passive microwave remote sensing instruments in space to measure parameters such as soil moisture and ocean salinity which require observations at long wavelengths and, therefore, large antennas. ESTAR is an L-band, aircraft prototype built as part of research to develop this technique. ESTAR is a hybrid real-and-synthetic aperture radiometer which employs stick antennas to achieve resolution along track and uses aperture synthesis to achieve resolution across track. Experiments to validate the instrument's ability to measure soil moisture have recently been conducted at the USDA watersheds at Walnut Gulch in Arizona and the Little Washita River in Oklahoma. The results of both experiments indicate that a valid image reconstruction and calibration have been obtained for this remote sensing technique. C1 UNIV MASSACHUSETTS,AMHERST,MA 01003. USDA ARS,HYDROL LAB,BELTSVILLE,MD 20705. RP LEVINE, DM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MICROWAVE SENSORS BRANCH,GREENBELT,MD 20771, USA. NR 50 TC 119 Z9 123 U1 1 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9219 J9 P IEEE JI Proc. IEEE PD DEC PY 1994 VL 82 IS 12 BP 1787 EP 1801 DI 10.1109/5.338071 PG 15 WC Engineering, Electrical & Electronic SC Engineering GA PW156 UT WOS:A1994PW15600003 ER PT J AU CARSWELL, JR CARSON, SC MCINTOSH, RE LI, FK NEUMANN, G MCLAUGHLIN, DJ WILKERSON, JC BLACK, PG NGHIEM, SV AF CARSWELL, JR CARSON, SC MCINTOSH, RE LI, FK NEUMANN, G MCLAUGHLIN, DJ WILKERSON, JC BLACK, PG NGHIEM, SV TI AIRBORNE SCATTEROMETERS - INVESTIGATING OCEAN BACKSCATTER UNDER LOW-WIND AND HIGH-WIND CONDITIONS SO PROCEEDINGS OF THE IEEE LA English DT Article ID RADAR CROSS-SECTION; X-BAND; ATMOSPHERIC STABILITY; SEA RETURN; SURFACE; DEPENDENCE; MODEL; SPEED; GHZ AB Attempting to understand and predict weather on a local and global basis has challenged both the scientific and engineering communities. One key parameter in understanding the weather is tire ocean surface wind vector because of its role in the energy exchange at the air-sea interface. Scatterometers, radars that measure the reflectivity of a tar-pet, offer a tool with which to remotely monitor these winds from tower-, aircraft-, and satellite-based platforms. This paper introduces three current airborne scatterometer systems, and presents data collected by these instruments under low-, moderate-, and high-wind conditions. Our paper focuses on airborne scatterometers because of their ability to resolve submesoscale variations in wind fields. Discrepancies between existing theory and the observations are noted and concerns in measuring low-wind speeds discussed. Finally, the application of using this technology for estimating the surface-wind vector during a hurricane is demonstrated. C1 ARCO POWER TECHNOL INC,WASHINGTON,DC 20009. NOAA,HURRICANE RES LAB,CORAL GABLES,FL 33145. NORTHEASTERN UNIV,DEPT ELECT & COMP ENGN,BOSTON,MA 02115. CALTECH,JET PROP LAB,SAR,SYST DEV & ENGN GRP,RADAR SCI & ENGN SECT,PASADENA,CA 91109. NOAA,NATL ENVIRONM SATELLITE DATA & INFORMAT SERV,SATELLITE RES LAB,WASHINGTON,DC 20233. RP CARSWELL, JR (reprint author), UNIV MASSACHUSETTS,DEPT ECE,MICROWAVE REMOTE SENSING LAB,AMHERST,MA 01003, USA. NR 59 TC 42 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 0018-9219 J9 P IEEE JI Proc. IEEE PD DEC PY 1994 VL 82 IS 12 BP 1835 EP 1860 DI 10.1109/5.338074 PG 26 WC Engineering, Electrical & Electronic SC Engineering GA PW156 UT WOS:A1994PW15600006 ER PT J AU LIM, K HO, JX KEELING, K GILLILAND, GL JI, XH RUKER, F CARTER, DC AF LIM, K HO, JX KEELING, K GILLILAND, GL JI, XH RUKER, F CARTER, DC TI 3-DIMENSIONAL STRUCTURE OF SCHISTOSOMA-JAPONICUM GLUTATHIONE-S-TRANSFERASE FUSED WITH A 6-AMINO ACID CONSERVED NEUTRALIZING EPITOPE OF GP41 FROM HIV SO PROTEIN SCIENCE LA English DT Article DE FUSION PROTEIN; GLUTATHIONE S-TRANSFERASE; HUMAN IMMUNODEFICIENCY VIRUS TYPE 1; SCHISTOSOMA JAPONICUM; 3-DIMENSIONAL STRUCTURE ID 3-DIMENSIONAL STRUCTURE; ESCHERICHIA-COLI; ACTIVE-SITE; PROTEIN; RESOLUTION; COMPLEX; PURIFICATION; REFINEMENT; ACTIVATION; MECHANISM AB The 3-dimensional crystal structure of glutathione S-transferase (GST) of Schistosoma japonicum (Sj) fused with a conserved neutralizing epitope on gp41 (glycoprotein, 41 kDa) of human immunodeficiency virus type 1 (HIV-1) (Muster T et al., 1993, J Virol 67:6642-6647) was determined at 2.5 Angstrom resolution. The structure of the 3-3 isozyme rat GST of the mu gene class (Ji X, Zhang P, Armstrong RN, Gilliland GL, 1992, Biochemistry 31:10169-10184) was used as a molecular replacement model. The structure consists of a 4-stranded beta-sheet and 3 alpha-helices in domain 1 and 5 alpha-helices in domain 2. The space group of the Sj GST crystal is P4(3)2(1)2, with unit cell dimensions of a = b = 94.7 Angstrom, and c = 58.1 Angstrom. The crystal has 1 GST monomer per asymmetric unit, and 2 monomers that form an active dimer are related by crystallographic 2-fold symmetry. In the binding site, the ordered structure of reduced glutathione is observed. The gp41 peptide (Glu-Leu-Asp-Lys-Trp-Ala) fused to the C-terminus of Sj GST forms a loop stabilized by symmetry-related GSTs. The Sj GST structure is compared with previously determined GST structures of mammalian gene classes mu, alpha, and pi. Conserved amino acid residues among the 4 GSTs that are important for hydrophobic and hydrophilic interactions for dimer association and glutathione binding are discussed. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,STRUCT BIOL LAB,BIOPHYS BRANCH ES76,HUNTSVILLE,AL 35812. UNIV MARYLAND,MARYLAND BIOTECHNOL INST,CTR ADV RES BIOTECHNOL,ROCKVILLE,MD 20850. NIST,ROCKVILLE,MD 20850. AGR UNIV VIENNA,INST ANGEW MIKROBIOL,A-1190 VIENNA,AUSTRIA. RI Ji, Xinhua/C-9664-2012 OI Ji, Xinhua/0000-0001-6942-1514 NR 55 TC 155 Z9 157 U1 2 U2 9 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0961-8368 J9 PROTEIN SCI JI Protein Sci. PD DEC PY 1994 VL 3 IS 12 BP 2233 EP 2244 PG 12 WC Biochemistry & Molecular Biology SC Biochemistry & Molecular Biology GA QF865 UT WOS:A1994QF86500009 PM 7538846 ER PT J AU KATZ, R ZACHARIAH, R CUCINOTTA, FA ZHANG, CX AF KATZ, R ZACHARIAH, R CUCINOTTA, FA ZHANG, CX TI SURVEY OF CELLULAR RADIOSENSITIVITY PARAMETERS SO RADIATION RESEARCH LA English DT Article ID DIFFERENT RADIATION SENSITIVITY; SURVIVAL; QUALITY; STRAINS; INACTIVATION; MUTAGENESIS; PARTICLES; CELLS; IONS AB A model of the formation of particle tracks in emulsion has been extended through the use of biological target theory to formulate a theory of the response of biological cells and molecules of biological importance to irradiation with energetic heavy ions. For this purpose the response to gamma rays is represented by the single-hit, multitarget model with parameters m and D-o, while additional parameters kappa (or a(o)) and sigma(o) are required to represent the size of internal cellular targets and the effective cross-sectional area of the cell nucleus, respectively, for heavy-ion bombardments. For one-or-more-hit detectors, only the first three of these parameters are required and m = 1. For cells m is typically 2 or more. The model is developed from the concept that response to secondary electrons follows the same functional form for gamma rays and for the delta rays surrounding an ion's path. Originally applied to dry enzymes and viruses in 1967, the model of the one-hit detector has been extended to emulsions, to other physical and chemical detectors, to single- and double-strand breaks in DNA in EO buffer and to three E. coli strains. The two-hit response has been observed for ''track core'' effects in radiation chemistry, for supralinearity in thermoluminescent dosimeters and for desensitized nuclear emulsions, where hit numbers up to 6 have been observed. In its extension to biological cells, additional concepts are required relating to the character of the track, namely the grain-count and track-width regimes, and to the ability of multitarget systems to acquire damage from intertrack delta rays (called gamma kill) as well as from intratrack delta rays (called ion kill). The model has been applied to some 40 sets of radiobiological data obtained from gamma, track-segment heavy-ion and neutron irradiations. Here we elaborate on the meaning of these concepts, tabulate the cellular parameters, and display their systematic behavior and the relationships among them. In particular the parameter kappa, which serves to determine the location in Z(*2)/beta(2) Of the maximum value of the RBE, shows little variation among cell types, while D-o, which describes the response to gamma rays and sigma(o), which appears to indicate the target size, varies over many orders of magnitude. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. ZHONGSHAN UNIV, CANTON, PEOPLES R CHINA. RP KATZ, R (reprint author), UNIV NEBRASKA, LINCOLN, NE 68588 USA. NR 37 TC 39 Z9 39 U1 0 U2 4 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD DEC PY 1994 VL 140 IS 3 BP 356 EP 365 DI 10.2307/3579113 PG 10 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA PV082 UT WOS:A1994PV08200008 PM 7972688 ER PT J AU KIMES, DS HARRISON, PA HARRISON, PR AF KIMES, DS HARRISON, PA HARRISON, PR TI EXTENSION OF OFF-NADIR VIEW ANGLES FOR DIRECTIONAL SENSOR SYSTEMS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID REFLECTANCE FACTOR DISTRIBUTIONS; RADIOMETER AB A knowledge-based system called VEG mns expanded to infer nadir or any off-nadir reflectance(s) of a vegetation target given any combination of other directional reflectance(s) of the target. VEG determines the best techniques to use in an array of techniques, applies the techniques to the target data, and provides a rigorous estimate of the accuracy of the inference(s). The knowledge-based system, VEG, facilitates the use of diverse knowledge bases to be incorporated into the inference techniques. In this study, VEG used additional information to make more accurate view-angle extension techniques than the traditional techniques that only use spectral data from the unknown target. VEG used spectral data and a normalized difference technique to infer the percentage of ground cover of the unknown target. This estimate of percentage of ground cover of the unknown target along with information on the sun angle were then used to search a historical data base for targets that match the unknown target in these characteristics. This data captured the general shape of the reflectance distribution of the unknown target. This historical information was used to estimate the coefficients of the techniques for the conditions at hand and to test the accuracy of the techniques. The tests used in this study were difficult ones. For example, techniques were tested that make long angular extensions using one, two, or four input view angles to predict an unknown nadir value. Furthermore, a wide variety of unknown targets were tested. The errors (+/- proportional rms) obtained were on the order of 0.15. In addition techniques were tested that use seven or nine multiple view angles to predict the entire hemispherical reflectance distribution of an unknown target. The accuracy of these tests was relatively good considering the relatively dynamic and noisy nature of directional reflectance distributions. The accuracy of the techniques in this study depends on the smoothness of the historical reflectance distributions and the amount of historical data available that closely matches the unknown target. C1 INTELLICORP,ARLINGTON,VA. USN ACAD,ANNAPOLIS,MD. RP KIMES, DS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,CODE 923,GREENBELT,MD 20771, USA. NR 16 TC 8 Z9 8 U1 0 U2 1 PU ELSEVIER SCIENCE PUBL CO 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 DEC PY 1994 VL 50 IS 3 BP 201 EP 211 DI 10.1016/0034-4257(94)90070-1 PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA QB673 UT WOS:A1994QB67300001 ER PT J AU CARTER, GA MILLER, RL AF CARTER, GA MILLER, RL TI EARLY DETECTION OF PLANT STRESS BY DIGITAL IMAGING WITHIN NARROW STRESS-SENSITIVE WAVEBANDS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RED EDGE; FOREST DECLINE; CHLOROPHYLL FLUORESCENCE; SPECTRAL MEASUREMENTS; NORWAY SPRUCE; SLASH PINE; BLUE-SHIFT; REFLECTANCE; LEAVES; TREES AB Digital images of soybean canopies [Glycine max (L.) Merrill] were obtained within selected narrow wavebands (6-10 nm bandwidths) to determine their capability for early detection of plant stress. Images and physiological measurements of stress were acquired 2 days, 4 days, and 7 days following application of control, drought, and herbicide [(3,4-dichlorophenyl)-1, 1-dimethylurea, or DCMU] treatments. As a result of frequent rainfall, drought stress never occurred. However, exposure to herbicide rapidly induced plant stress. By day 4, the ratio of variable to maximum of leaf fluorescence (F-v/F-m) decreased and leaf water potentials (psi(w)) increased in the herbicide treated soybean, indicating damage to the photosynthetic apparatus and stomatal closure. Also, Munsell leaf color had increased from approximately 5GY 4.6/5.7 to a lighter green-yellow value. Canopy reflectances at 670 nm , 694 nm, and in the 410-740 nm band (R(vis)), as well as reflectance at 694 nm divided by reflectance at 760 nm (R(694)/R(760)), detected stress simultaneously with the physiological measurements and increased consistently with stress through day 7. Reflectances at 420 nm and 600 nm, together with R(600)/R(760) and R(vis)/R(760), did not increase until leaves were yellow or brown and wilted and canopies had begun to collapse on day 7. None of the reflectance or reflectance ratio images detected stress prior to visible color changes. This was attributed primarily to the rapid inducement of chlorosis by the herbicide. Reflectance in narrow wavebands within the 690-700 nm region and its ratio with near-infrared reflectance should provide earlier detection of stress-induced chlorosis compared with broad band systems or narrow bands located at lesser wavelengths. RP CARTER, GA (reprint author), NASA,EARTH OBSERVAT RES OFF,BAY ST LOUIS,MS 39529, USA. NR 34 TC 127 Z9 137 U1 1 U2 22 PU ELSEVIER SCIENCE PUBL CO 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 DEC PY 1994 VL 50 IS 3 BP 295 EP 302 DI 10.1016/0034-4257(94)90079-5 PG 8 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA QB673 UT WOS:A1994QB67300010 ER PT J AU MARTONCHIK, JV AF MARTONCHIK, JV TI RETRIEVAL OF SURFACE DIRECTIONAL REFLECTANCE PROPERTIES USING GROUND-LEVEL MULTIANGLE MEASUREMENTS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID IMAGING SPECTRORADIOMETER; BIDIRECTIONAL REFLECTANCE; FACTOR DISTRIBUTIONS; OPTICAL-PROPERTIES; ALBEDO; SATELLITE; RADIANCE AB Knowledge of the directional reflectance properties of natural surfaces such as soils and vegetation canopies is essential for classification studies and canopy model inversion. Atmospheric correction schemes, using various levels of approximation, are described to retrieve surface bidirectional reflectance factors (BRFs) and directional-hemispherical reflectances (albedos)from multiangle radiance measurements taken at ground level. The retrieval schemes are tested on simulated data incorporating realistic surface BRFs and atmospheric models containing aerosols. Sensitivity of the atmospherically corrected BRFs and associated directional-hemispherical reflectances to various aerosol properties and the sun-view geometry is illustrated. A measurement strategy for obtaining highly accurate surface reflectance properties also is examined in the context of instrument radiometric calibration, knowledge of the atmospheric properties, and sun-view angular coverage. RP MARTONCHIK, JV (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MAIL STOP 169-237,PASADENA,CA 91109, USA. NR 22 TC 34 Z9 34 U1 1 U2 4 PU ELSEVIER SCIENCE PUBL CO 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 DEC PY 1994 VL 50 IS 3 BP 303 EP 316 DI 10.1016/0034-4257(94)90080-9 PG 14 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA QB673 UT WOS:A1994QB67300011 ER PT J AU BROWN, LW WOODGATE, BE ZIEGLER, MM KENNY, PJ OLIVERSEN, RJ AF BROWN, LW WOODGATE, BE ZIEGLER, MM KENNY, PJ OLIVERSEN, RJ TI GODDARD-SPACE-FLIGHT-CENTER ASTRONOMICAL FABRY-PEROT IMAGING CAMERA SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID GALAXY RP BROWN, LW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Woodgate, Bruce/D-2970-2012 NR 19 TC 4 Z9 4 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 DEC PY 1994 VL 65 IS 12 BP 3611 EP 3615 DI 10.1063/1.1145216 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA PX392 UT WOS:A1994PX39200001 ER PT J AU WANG, XL VAUGHAN, DE PELEKHATY, V CRISP, J AF WANG, XL VAUGHAN, DE PELEKHATY, V CRISP, J TI A NOVEL MINIATURE SPECTROMETER USING AN INTEGRATED ACOUSTOOPTIC TUNABLE FILTER SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP WANG, XL (reprint author), BRIMROSE CORP AMER,5020 CAMPBELL BLVD,BALTIMORE,MD 21236, USA. RI Crisp, Joy/H-8287-2016 OI Crisp, Joy/0000-0002-3202-4416 NR 17 TC 10 Z9 10 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 DEC PY 1994 VL 65 IS 12 BP 3653 EP 3656 DI 10.1063/1.1145201 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA PX392 UT WOS:A1994PX39200008 ER PT J AU EVANS, DL STOFAN, ER JONES, TD GODWIN, LM AF EVANS, DL STOFAN, ER JONES, TD GODWIN, LM TI EARTH FROM SKY SO SCIENTIFIC AMERICAN LA English DT Article RP EVANS, DL (reprint author), JET PROPULS LAB,PASADENA,CA, USA. NR 2 TC 6 Z9 6 U1 1 U2 1 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 SN 0036-8733 J9 SCI AM JI Sci.Am. PD DEC PY 1994 VL 271 IS 6 BP 70 EP 75 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PT544 UT WOS:A1994PT54400025 ER PT J AU MECHERIKUNNEL, AT AF MECHERIKUNNEL, AT TI A COMPARISON OF SOLAR TOTAL IRRADIANCE OBSERVATIONS FROM SPACECRAFT - 1985-1992 SO SOLAR PHYSICS LA English DT Article ID LUMINOSITY; VARIABILITY; NIMBUS-7 AB This paper presents a statistical comparison of the solar total irradiance measured from the Nimbus-7, the Solar Maximum Mission (SMM), the Earth Radiation Budget Satellite (ERBS), and the Upper Atmosphere Research Satellite (UARS) spacecraft platforms, for the period 1985 - 1992. The mean irradiance, standard deviation, and the correlation among the daily irradiance remained high during periods of high solar activity. Linear regression models are established to estimate the irradiance measurements from one platform by the others. The results are consistent with the observations. However, the Nimbus-7 ERB responses show a drift during 1989-1992. The absolute irradiance observed by each instrument varies within the uncertainty associated with the corresponding radiometer. RP MECHERIKUNNEL, AT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 20 TC 8 Z9 8 U1 1 U2 2 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 DEC PY 1994 VL 155 IS 2 BP 211 EP 221 DI 10.1007/BF00680591 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG316 UT WOS:A1994QG31600001 ER PT J AU SLENES, K ACKERMAN, WC BROTZMAN, RW STOLTZFUS, J GUNAJI, M AF SLENES, K ACKERMAN, WC BROTZMAN, RW STOLTZFUS, J GUNAJI, M TI CERAMIC COATINGS THAT INCREASE WEAR-RESISTANCE AND SUPPRESS THE IGNITION OF 316-STAINLESS-STEEL IN AN OXYGEN ENVIRONMENT SO SURFACE & COATINGS TECHNOLOGY LA English DT Article; Proceedings Paper CT 21st International Conference on Metallurgical Coatings and Thin Films CY APR 25-29, 1994 CL SAN DIEGO, CA SP Amer Vacuum Soc, Vacuum Met Div, Amer Vacuum Soc, Thin Film Div AB Many materials that are not considered to be flammable in air can ignite and burn in oxygen environments, for example stainless steel (SS) will burn vigorously when ignited in a 1000 psi (6.9 MPa) oxygen environment. Advancing technology is creating a demand for higher oxygen-use temperatures and pressures, e.g. NASA propulsion systems. Fires in oxygen systems are generally catastrophic, causing damage to equipment and a threat to life. Aluminosilicate (47 wt.%) coatings were applied to 316 SS substrates using sol-gel techniques; a proprietary coupling agent effects covalent bonding. Coated coupons were subjected to six 600 degrees C s(-1) thermal quench cycles with no interface failure and the coatings did not crack. The aluminosilicate coating reduced wear rates by 88.2% and 52.9 % For 50 g normal force and 150 g normal force, respectively. There is no decrease in substrate biflexure strength with processing of the aluminosilicate coating. Coated and uncoated specimens were subjected to frictional heating experiments in an oxygen environment at the White Sands Test Facility. Aluminosilicate coatings suppress the ignition of 316 SS; measured pressure-velocity products are independent of coating thickness and appear to be composition dependent. C1 NASA,WHITE SANDS TEST FACIL,LAS CRUCES,NM 88004. RP SLENES, K (reprint author), TPL INC,3768 HAWKINS NE,ALBUQUERQUE,NM 87109, USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0257-8972 J9 SURF COAT TECH JI Surf. Coat. Technol. PD DEC PY 1994 VL 68 BP 51 EP 57 DI 10.1016/0257-8972(94)90137-6 PG 7 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA PW039 UT WOS:A1994PW03900010 ER PT J AU SPALVINS, T SLINEY, HE AF SPALVINS, T SLINEY, HE TI FRICTIONAL BEHAVIOR AND ADHESION OF AG AND AU FILMS APPLIED TO ALUMINUM-OXIDE BY OXYGEN-ION ASSISTED SCREEN CAGE ION PLATING SO SURFACE & COATINGS TECHNOLOGY LA English DT Article; Proceedings Paper CT 21st International Conference on Metallurgical Coatings and Thin Films CY APR 25-29, 1994 CL SAN DIEGO, CA SP Amer Vacuum Soc, Vacuum Met Div, Amer Vacuum Soc, Thin Film Div AB A modified d.c. diode ion plating system, by utilizing a metallic screen cage as a cathode, is introduced for coating non-conductors such as ceramics. Screen cage ion plating (SCIP) is used to apply Ag and Au lubricating films on aluminum oxide surfaces. This process has excellent ability to coat around corners to produce three-dimensional coverage of the substrate. A dramatic increase in adhesion is achieved when plating is performed in a reactive 50% O-2-50% Ar glow discharge compared with the adhesion when plating is performed in 100% Ar. The presence of oxygen ion assistance contributes to the excellent adhesion as measured in a pull-type adhesion tester. The Ag and Au film adhesion is significantly increased (above 70 MPa) and generally exceeds the cohesion of the substrate such that portions of the alumina are pulled out. The deposited Ag and Au lubricating films not only reduce the coefficient of friction during sliding contact but also reduce the surface tensile stresses that contribute to undesirable subsurface cracking and subsequently to severe wear. The strong adhesion of Ag and Au films to alumina imparted by reactive SCIP is of critical importance in achieving low and steady friction coefficients and low wear. RP SPALVINS, T (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 13 TC 13 Z9 13 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0257-8972 J9 SURF COAT TECH JI Surf. Coat. Technol. PD DEC PY 1994 VL 68 BP 482 EP 488 DI 10.1016/0257-8972(94)90205-4 PG 7 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA PW039 UT WOS:A1994PW03900078 ER PT J AU ROZAS, LP REED, DJ AF ROZAS, LP REED, DJ TI COMPARING NEKTON ASSEMBLAGES OF SUBTIDAL HABITATS IN PIPELINE CANALS TRAVERSING BRACKISH AND SALINE MARSHES IN COASTAL LOUISIANA SO WETLANDS LA English DT Article DE PIPELINE CANALS; FISHERY IMPACT; LOUISIANA; SUBTIDAL HABITAT; SUBMERGED AQUATIC VEGETATION; HURRICANE IMPACT; BACKFILLING AB Subtidal habitats of pipeline canals in Louisiana brackish and saline marshes were sampled seasonally (fall, spring, and summer) between October 1991 and March 1993 with a 2-m(2) throw trap to identify dominant natant species and test hypotheses relating habitat selection to water depth. Densities of nekton were compared among canals and between shallow (<1 m) and deep (greater than or equal to Im) areas within canals to test two null hypotheses: H-1: Densities of nekton in pipeline canals are not related to maximum canal depth and H-2: Densities of nekton in shallow and deep subtidal areas of canals are equal. Daggerblade grass shrimp Palaemonetes pugio, bay anchovy Anchoa mitchilli, blue crab Callinectes sapidus, brown shrimp Penaeus aztecus, and gulf menhaden Brevoortia patronus numerically dominated nekton assemblages in both brackish and saline canals. Naked goby Gobiosoma bose, rainwater killifish Lucania parva, and gulf pipefish Syngnathus scovelli were dominant only in brackish canals, whereas white shrimp Penaeus setiferus and Atlantic croaker Micropogonias undulatus were abundant in saline canals only. Although variation in the abundance of most numerically dominant species could not be related to maximum canal depth, the distribution of several species within pipeline canals was influenced by habitat depth and other interrelated factors. The degree of habitat segregation with depth was largely influenced by submerged aquatic vegetation (SAV) and salinity as well as water depth. Habitat segregation with depth was most pronounced in brackish canals during late spring (May) when SAV was present. Naked goby, rainwater killifish, blue crabs, and daggerblade grass shrimp were significantly more abundant in shallow water (<1 m) at this time. In saline canals, most blue crabs and daggerblade grass shrimp occupied shallow habitats in March when small juveniles of these species reached peak abundance. Bay anchovy exhibited a pattern opposite that of other species. In March, bay anchovy abundance was positively related to maximum canal depth in brackish canals, and densities were greater in deep than shallow areas of saline canals in June. Salinity may have affected the distribution of freshwater species (e.g., centrarchids) and limited their occurrence in saline canals. Increasing shallow subtidal habitat by backfilling canals may enhance the nursery habitat for some species, especially in brackish canals where the area of subtidal habitat capable of supporting SAV would be expanded. RP ROZAS, LP (reprint author), NOAA,NATL MARINE FISHERIES SERV,SE FISHERIES SCI CTR,4700 AVE U,GALVESTON,TX 77551, USA. NR 0 TC 15 Z9 15 U1 0 U2 4 PU SOC WETLAND SCIENTISTS PI LAWRENCE PA 810 E TENTH ST, P O BOX 1897, LAWRENCE, KS 66044 SN 0277-5212 J9 WETLANDS JI Wetlands PD DEC PY 1994 VL 14 IS 4 BP 262 EP 275 PG 14 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA PZ385 UT WOS:A1994PZ38500002 ER PT J AU ZHU, J SHIH, TH AF ZHU, J SHIH, TH TI COMPUTATION OF CONFINED COFLOW JETS WITH 3 TURBULENCE MODELS SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE TURBULENCE MODELS; CONFINED JETS; RECIRCULATION ID INCOMPRESSIBLE FLOWS AB A numerical study of confined jets in a cylindrical duct is carried out to examine the performance of two recently proposed turbulence models: an RNG-based K-epsilon model and a realizable Reynolds stress algebraic equation model. The former is of the same form as the standard K-epsilon model but has different model coefficients. The latter uses an explicit quadratic stress-strain relationship to model the turbulent stresses and is capable of ensuring the positivity of each turbulent normal stress. The flow considered involves recirculation with unfixed separation and reatachment points and severe adverse pressure gradients, thereby providing a valuable test of the predictive capability of the models for complex flows. Calculations are performed with a finite volume procedure. Numerical credibility of the solutions is ensured by using second-order-accurate differencing schemes and sufficiently fine grids. Calculations with the standard K-epsilon model are also made for comparison. Detailed comparisons with experiments show that the realizable Reynolds stress algebraic equation model consistently works better than does the standard K-epsilon model in capturing the essential flow features, while the RNG-based K-epsilon model does not seem to give improvements over the standard K-epsilon model under the flow conditions considered. C1 NASA,LEWIS RES CTR,CTR MODELING TURBULENCE & TRANSIT,CLEVELAND,OH 44135. RP ZHU, J (reprint author), NASA,LEWIS RES CTR,INST COMPUTAT MECH PROP,CLEVELAND,OH 44135, USA. NR 25 TC 20 Z9 21 U1 0 U2 3 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 NOV 30 PY 1994 VL 19 IS 10 BP 939 EP 956 DI 10.1002/fld.1650191005 PG 18 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA PU236 UT WOS:A1994PU23600004 ER PT J AU BRAGE, T FISCHER, CF AF BRAGE, T FISCHER, CF TI SPLINE-GALERKIN METHODS FOR RYDBERG SERIES, INCLUDING BREIT-PAULI EFFECTS SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID HARTREE-FOCK CALCULATIONS; B-SPLINES; NONRADIATIVE DECAY; CROSS-SECTIONS; FINITE BASIS; BASIS-SETS; STATES; EQUATION; PHOTOIONIZATION; ATOMS AB We discuss the recently introduced spline-Galerkin method for Rydberg series of atomic systems, and extend it to Breit-Pauli configuration interaction calculations. Special emphasis is put on the efficient evaluation of the different radial integrals appearing in these calculations. An application to the 1De series of beryllium illustrates the potential of the method in the non-relativistic case. A Breit-Pauli calculation for the J = 1 odd Rydberg series above the lowest 4s 2S limit of calcium is reported. The resulting energies agree very well with recent experiments. C1 VANDERBILT UNIV,DEPT COMP SCI,NASHVILLE,TN 37235. RP BRAGE, T (reprint author), GODDARD SPACE FLIGHT CTR,CODE 681,GREENBELT,MD 21042, USA. OI Brage, Tomas/0000-0003-3985-767X NR 54 TC 9 Z9 10 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD NOV 28 PY 1994 VL 27 IS 22 BP 5467 EP 5484 DI 10.1088/0953-4075/27/22/007 PG 18 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PV228 UT WOS:A1994PV22800007 ER PT J AU SHARIFF, K VERZICCO, R ORLANDI, P AF SHARIFF, K VERZICCO, R ORLANDI, P TI A NUMERICAL STUDY OF 3-DIMENSIONAL VORTEX RING INSTABILITIES - VISCOUS CORRECTIONS AND EARLY NONLINEAR STAGE SO JOURNAL OF FLUID MECHANICS LA English DT Article ID 3-DIMENSIONAL INSTABILITY; SHORT WAVES; VORTICES; STABILITY; STRAIN; FLUID; LAYER; FIELD; FLOW AB Finite-difference calculations with random and single-mode perturbations are used to study the three-dimensional instability of vortex rings. The basis of current understanding of the subject consists of a heuristic inviscid model (Widnall, Bliss and Tsai 1974) and a rigorous theory which predicts growth rates for thin-core uniform vorticity rings (Widnall and Tsai 1977). At sufficiently high Reynolds numbers the results correspond qualitatively to those predicted by the heuristic model: multiple bands of wavenumbers are amplified, each band having a distinct radial structure. However, a viscous correction factor to the peak inviscid growth rate is found. It is well described by the first term, 1 - alpha(1)(beta)/Re-s, for a large range of Re-s. Here Re-s is the Reynolds number defined by Saffman (1978), which involves the curvature-induced strain rate. It is found to be the appropriate choice since then alpha(1)(beta) varies weakly with core thickness beta. The three most nonlinearly amplified modes are a mean azimuthal velocity in the form of opposing streams, an n = 1 mode (n is the azimuthal wavenumber) which arises from the interaction of two second-mode bending waves and the harmonic of the primary second mode. When a single wave is excited, higher harmonics begin to grow successively later with nonlinear growth rates proportional to n. The modified mean flow has a doubly peaked azimuthal vorticity. Since the curvature-induced strain is not exactly stagnation-point flow there is a preference for elongation towards the rear of the ring: the outer structure of the instability wave forms a long wake consisting of n hairpin vortices whose waviness is phase shifted pi/n relative to the waviness in the core. Whereas the most amplified linear mode has three radial layers of structure, higher radial mode;s having more layers of radial structure (hairpins piled upon hairpins) are excited when the initial perturbation is large, reminiscent of visualization experiments on the formation of a turbulent ring at the generator. C1 UNIV ROMA LA SAPIENZA, DIPARTIMENTO MECCAN & AERONAUT, I-00184 ROME, ITALY. RP NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. OI Shariff, Karim/0000-0002-7256-2497 NR 34 TC 52 Z9 53 U1 0 U2 5 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 NOV 25 PY 1994 VL 279 BP 351 EP 375 DI 10.1017/S0022112094003939 PG 25 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PW602 UT WOS:A1994PW60200014 ER PT J AU ALLEN, CC MORRIS, RV MCKAY, DS AF ALLEN, CC MORRIS, RV MCKAY, DS TI EXPERIMENTAL REDUCTION OF LUNAR MARE SOIL AND VOLCANIC GLASS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB We have reduced high-titanium lunar mare soil and iron-rich lunar volcanic glass with hydrogen at temperatures of 900-1100 degrees C. Ilmenite is the most reactive phase in the soil, exhibiting rapid and complete reduction at all temperatures. Ferrous iron in the glass is extensively reduced concurrent with partial crystallization. In both samples pyroxene and olivine undergo partial reduction along with chemical and mineralogical modifications. High-temperature reduction provides insight into the optical and chemical effects of lunar soil maturation, and places constraints on models of that process. Mate soil and volcanic glass ate attractive feedstocks for lunar oxygen production, with achievable yields of 2-5 wt%. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP ALLEN, CC (reprint author), LOCKHEED ENGN & SCI CO,MAIL CODE C23,2400 NASA RD 1,HOUSTON,TX 77058, USA. NR 38 TC 19 Z9 19 U1 3 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 NOV 25 PY 1994 VL 99 IS E11 BP 23173 EP 23185 DI 10.1029/94JE02321 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PU306 UT WOS:A1994PU30600003 ER PT J AU ATLAS, D AF ATLAS, D TI ORIGIN OF STORM FOOTPRINTS ON THE SEA SEEN BY SYNTHETIC-APERTURE RADAR SO SCIENCE LA English DT Article ID NUMERICAL SIMULATIONS; ISOLATED MICROBURST; RAIN; SCATTERING; WAVES AB Spaceborne synthetic aperture radar can detect storm footprints on the sea. Coastal weather radar from Cape Hatteras provides evidence that the echo-free hole at the footprint core is the result of wave damping by rain. The increased radar cross section of the sea surrounding the echo-free hole results from the divergence of the precipitation-forced downdraft impacting the sea. The footprint boundary is the gust front; its orientation is aligned with the direction of the winds aloft, which are transported down with the downdraft, and its length implies downdraft impact 1 hour earlier at a quasi-stationary impact spot. The steady, localized nature of the storm remains a mystery. RP ATLAS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 22 TC 27 Z9 27 U1 1 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD NOV 25 PY 1994 VL 266 IS 5189 BP 1364 EP 1366 DI 10.1126/science.266.5189.1364 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PT632 UT WOS:A1994PT63200038 PM 17772844 ER PT J AU BERNSTEIN, MP SANDFORD, SA ALLAMANDOLA, LJ CHANG, S AF BERNSTEIN, MP SANDFORD, SA ALLAMANDOLA, LJ CHANG, S TI INFRARED-SPECTRUM OF MATRIX-ISOLATED HEXAMETHYLENETETRAMINE IN AR AND H2O AT CRYOGENIC TEMPERATURES SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID ABSORPTION FEATURES; ICE ANALOGS; SOLID ARGON; BAND; CO; MOLECULES; ATOMS AB The infrared specta of hexamethylenetetramine (HMT) isolated in an argon matrix at 12 K, frozen in H2O at temperatures from 12 to 200 K, and as a pure solid, are reported. The results of ultraviolet photolysis of matrix-isolated HMT and HMT frozen in H2O ice are also presented, and implications for infrared astronomy and astrochemistry are discussed. Furthermore, a simple technique for incorporating large nonvolatile organic molecules into a matrix is described. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 41 TC 43 Z9 43 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 NOV 24 PY 1994 VL 98 IS 47 BP 12206 EP 12210 DI 10.1021/j100098a014 PG 5 WC Chemistry, Physical SC Chemistry GA PT762 UT WOS:A1994PT76200014 ER PT J AU LIEBERMAN, P PROTOPAPAS, A REED, E YOUNGS, JW KANKI, BG AF LIEBERMAN, P PROTOPAPAS, A REED, E YOUNGS, JW KANKI, BG TI COGNITIVE DEFECTS AT ALTITUDE SO NATURE LA English DT Letter C1 NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035. RP LIEBERMAN, P (reprint author), BROWN UNIV,DEPT COGNIT & LINGUIST SCI,PROVIDENCE,RI 02912, USA. RI Protopapas, Athanassios/A-9571-2009; Protopapas, Athanassios/E-5626-2010 OI Protopapas, Athanassios/0000-0002-7285-8845 NR 6 TC 36 Z9 38 U1 0 U2 6 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD NOV 24 PY 1994 VL 372 IS 6504 BP 325 EP 325 DI 10.1038/372325a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PU287 UT WOS:A1994PU28700036 PM 7969487 ER PT J AU MEARINI, GT KRAINSKY, IL DAYTON, JA WANG, YX ZORMAN, CA ANGUS, JC HOFFMAN, RW AF MEARINI, GT KRAINSKY, IL DAYTON, JA WANG, YX ZORMAN, CA ANGUS, JC HOFFMAN, RW TI STABLE SECONDARY-ELECTRON EMISSION OBSERVATIONS FROM CHEMICAL-VAPOR-DEPOSITED DIAMOND SO APPLIED PHYSICS LETTERS LA English DT Article C1 CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. RP MEARINI, GT (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. OI Zorman, Christian/0000-0001-9773-9351 NR 6 TC 39 Z9 39 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD NOV 21 PY 1994 VL 65 IS 21 BP 2702 EP 2704 DI 10.1063/1.112611 PG 3 WC Physics, Applied SC Physics GA PT872 UT WOS:A1994PT87200026 ER PT J AU HOGE, FE AF HOGE, FE TI ASYMMETRICAL SPECTRAL CURVATURE ALGORITHMS - OCEANIC-CONSTITUENTS SENSITIVITIES SO APPLIED OPTICS LA English DT Article ID CHLOROPHYLL; COLOR; COCCOLITHOPHORE; VARIABILITY AB The asymmetrical spectral curvature algorithm for Morel case 1 waters has been characterized by application of the semianalytical radiance model of ocean color to post-Coastal Zone Color Scanner (CZCS) sensor bands. Results of the study suggest that the [L(490)/L(443)][L(490)/L(555)] asymmetrical spectral curvature algorithm has a higher pigment-retrieval sensitivity than does the [L(490)/L(443)][L(490)/L(510)] curvature algorithm that was initially identified for pigment recovery. When this [L (490)/L(443)][L(490)/L(555)] algorithm was highlighted for study, it was found to (a) exhibit pigment-retrieval sensitivity that is intermediate to the [L(443)/L(555)] and the [L(510)/L(555)] CZCS-type radiance-ratio algorithms, (b) have less sensitivity to nonabsorbing particulate backscatter (NAB) than the [L(443)/L(555)] radiance ratio, (c) display remarkable insensitivity to the absorption of dissolved organic material (DOM), and (d) possess a NAB invariance point at an algorithm value of similar to 1.8 (corresponding to a pigment concentration of similar to 0.35 mg/m(3)). At this invariance point the [L(490)/L(443)][L(490)/L(555)] algorithm is insensitive to a wide concentration range of coccolith-like backscatterers in addition to being insensitive to DOM. The dual DOM and NAB insensitivity of the algorithm at a specific curvature value and chlorophyllous-pigment concentration suggests that such invariance points should be further studied for possible use in (1) the validation of other chlorophyllous-pigment algorithms or model inversions and (2) the computation of other inherent optical properties. RP HOGE, FE (reprint author), GODDARD SPACE FLIGHT CTR, WALLOPPS FLIGHT FACIL, WALLOPS ISL, VA 23337 USA. NR 14 TC 1 Z9 1 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD NOV 20 PY 1994 VL 33 IS 33 BP 7764 EP 7769 PG 6 WC Optics SC Optics GA PW744 UT WOS:A1994PW74400011 PM 20962987 ER PT J AU HUNTER, SD DIGEL, SW DEGEUS, EJ KANBACH, G AF HUNTER, SD DIGEL, SW DEGEUS, EJ KANBACH, G TI GAMMA-RAY OBSERVATIONS OF OPHIUCHUS WITH EGRET - THE DIFFUSE EMISSION AND POINT SOURCES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS; ISM, CLOUDS; ISM, INDIVIDUAL (RHO OPHIUCHUS); GAMMA RAYS, OBSERVATIONS; QUASARS, INDIVIDUAL (PKS 1622-253) ID COSMIC-RAY; MOLECULAR CLOUDS; RADIAL-DISTRIBUTION; CO SURVEY; CARBON-MONOXIDE; STELLAR WINDS; DARK CLOUDS; MILKY-WAY; GALAXY; GAS AB Observations of the Ophiuchus region made with the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory during the first 2 1/2 years of operation show the diffuse emission from the interstellar gas in Ophiuchus as well as variable emission from two point sources. The gamma-ray emission is modeled in terms of cosmic-ray interactions with atomic and molecular hydrogen in Ophiuchus and with low-energy photons along the line of sight. The model also includes the flux from the two point sources and an isotropic diffuse contribution. The cosmic-ray density is assumed to be uniform. The derived ratio of molecular hydrogen column density to integrated CO intensity is (1.1 +/- 0.2) x 10(20) H-mols cm(-2) (K km s(-1))(-1). At the sensitivity and resolution of the gamma-ray data, no variation of this ratio over the modeled region is discernible, nor are any regions of enhanced cosmic-ray density apparent. The model was fitted to seven narrow energy bands to obtain the energy dependence of the gamma-ray production function and the spectra of the point sources. The derived production function is in good agreement with theoretical calculations and the local cosmic-ray electron and proton spectra. The positions of the point sources were determined from maximum likelihood analysis of the gamma-ray emission observed in excess of the diffuse model. We identify one point source with the quasar PKS 1622-253, which has an average flux, E > 100 MeV, of (2.5 +/- 0.5) x 10(-7) photons cm(-2) s(-1) and photon spectral index -1.9 +/- 0.3. The other source, denoted GRO J1631-27, has not yet been identified at other wavelengths. Its average flux, E > 100 MeV, is (1.1 +/- 0.4) x 10(-7) photons cm(-2) s(-1); however, its spectral index is poorly determined. The spectral index and intensity of the isotropic contribution to the model agree well with the extragalactic diffuse emission derived from the SAS 2 data. C1 HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. CALTECH, DEPT ASTRON, PASADENA, CA 91125 USA. MAX PLANCK INST EXTRATERR PHYS, D-85748 GARCHING, GERMANY. RP HUNTER, SD (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 662, GREENBELT, MD 20771 USA. RI Hunter, Stanley/D-2942-2012 NR 65 TC 43 Z9 43 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 NOV 20 PY 1994 VL 436 IS 1 BP 216 EP 228 DI 10.1086/174894 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR932 UT WOS:A1994PR93200021 ER PT J AU THOMPSON, DJ ARZOUMANIAN, Z BERTSCH, DL BRAZIER, KTS CHIANG, J DAMICO, N DINGUS, BL ESPOSITO, JA FIERRO, JM FICHTEL, CE HARTMAN, RC HUNTER, SD JOHNSTON, S KANBACH, G KASPI, VM KNIFFEN, DA LIN, YC LYNE, AG MANCHESTER, RN MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NEL, HI NICE, DJ NOLAN, PL RAMANAMURTHY, PV SHEMAR, SL SCHNEID, EJ SREEKUMAR, P TAYLOR, JH AF THOMPSON, DJ ARZOUMANIAN, Z BERTSCH, DL BRAZIER, KTS CHIANG, J DAMICO, N DINGUS, BL ESPOSITO, JA FIERRO, JM FICHTEL, CE HARTMAN, RC HUNTER, SD JOHNSTON, S KANBACH, G KASPI, VM KNIFFEN, DA LIN, YC LYNE, AG MANCHESTER, RN MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NEL, HI NICE, DJ NOLAN, PL RAMANAMURTHY, PV SHEMAR, SL SCHNEID, EJ SREEKUMAR, P TAYLOR, JH TI EGRET HIGH-ENERGY GAMMA-RAY PULSAR STUDIES .1. YOUNG SPIN-POWERED PULSARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS; PULSARS, GENERAL ID RADIO PULSARS; COS-B; RADIATION; EMISSION; GEMINGA; TELESCOPE; CRAB; ASTRONOMY; SEARCHES; GEOMETRY AB As part of its ongoing survey of the high-energy gamma-ray sky, the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has searched for emission from spin-powered pulsars, five of which have now been detected in the energy range 30 MeV less than or equal to E less than or equal to 20 GeV. A systematic study of the all-sky survey has found no additional pulsed gamma-ray sources. The pulsar detections, coupled with the upper limits on pulsed gamma radiation from other radio pulsars, indicate that the simplest models of gamma-ray pulsars are incomplete. C1 PRINCETON UNIV, DEPT PHYS, PRINCETON, NJ 08544 USA. MAX PLANCK INST EXTRATERR PHYS, D-85748 GARCHING, GERMANY. STANFORD UNIV, WW HANSEN EXPTL PHYS LAB, STANFORD, CA 94305 USA. STANFORD UNIV, DEPT PHYS, STANFORD, CA 94305 USA. UNIV PALERMO, IST FIS, I-40126 PALERMO, ITALY. CNR, IST RADIOASTRON, I-40126 BOLOGNA, ITALY. CSIRO, AUSTRALIA TELESCOPE NATL FACIL, EPPING, NSW 2121, AUSTRALIA. UNIV MANCHESTER, DEPT PHYS, MACCLESFIELD SK11 9DL, CHESHIRE, ENGLAND. POTCHEFSTROOM UNIV CHRISTIAN HIGHER EDUC, DEPT PHYS, POTCHEFSTROOM 2520, SOUTH AFRICA. GRUMMAN AEROSP CORP, BETHPAGE, NY 11714 USA. RP THOMPSON, DJ (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 662, GREENBELT, MD 20771 USA. RI Nolan, Patrick/A-5582-2009; D'Amico, Nichi/A-5715-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; OI Thompson, David/0000-0001-5217-9135; Dingus, Brenda/0000-0001-8451-7450 NR 67 TC 105 Z9 105 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP 229 EP 238 DI 10.1086/174895 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR932 UT WOS:A1994PR93200022 ER PT J AU ANTUNES, A NAGASE, F WHITE, NE AF ANTUNES, A NAGASE, F WHITE, NE TI ASCA OBSERVATIONS OF THE CORONAL X-RAY-EMISSION OF ALGOL SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ABUNDANCES; STARS, CORONAE; STARS, INDIVIDUAL (ALGOL); X-RAYS, STARS ID ABUNDANCES; SOLAR; STARS AB We report a 1.7 day ASCA X-ray observation of the 2.87 day binary Algol (beta Per), centered on the secondary eclipse. Spectra accumulated for different intensity states show a prominent He-like iron K line at 6.7 keV. A two-temperature variable abundance plasma model applied to the spectra yielded temperatures of similar to 8 and similar to 30 MK. The modeled coronal abundances of Fe, O, Mg, Si, S, Ar, and Ca were a factor of 2-3 below the solar photospheric value, and N < 0.1. These model abundance anomalies are similar to those found from the ASCA spectra of other late-type stars and may indicate either true deviations from solar abundances or problems with the assumptions and atomic physics of the plasma models. The X-ray light curve shows a factor of 2 increase in flux over 13 hr beginning in the middle of the secondary eclipse, with a shallow eclipse centered on phase 0.45. The orbital light curve is similar to that observed by ROSAT 1 year earlier. The rise in flux is caused by an increase in the emission measure of the higher temperature component. The intensity variation is not associated with any major change in the abundances or temperature of the two components. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP ANTUNES, A (reprint author), INST SPACE & ASTRONAUT SCI,3-1-1 YOSHINODAI,SAGAMIHARA,KANAGAWA 229,JAPAN. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 19 TC 44 Z9 44 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 NOV 20 PY 1994 VL 436 IS 1 BP L83 EP L86 DI 10.1086/187638 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300020 ER PT J AU ARNAUD, KA MUSHOTZKY, RF EZAWA, H FUKAZAWA, Y OHASHI, T BAUTZ, MW CREWE, GB GENDREAU, KC YAMASHITA, K KAMATA, Y AKIMOTO, F AF ARNAUD, KA MUSHOTZKY, RF EZAWA, H FUKAZAWA, Y OHASHI, T BAUTZ, MW CREWE, GB GENDREAU, KC YAMASHITA, K KAMATA, Y AKIMOTO, F TI TEMPERATURE AND IRON ABUNDANCE VARIATION OF THE GAS IN THE PERSEUS CLUSTER SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, CLUSTERS OF ID X-RAY OBSERVATIONS; DARK MATTER; GALAXIES; EVOLUTION AB We present the first two-dimensional map of the temperature and iron abundance in the Perseus cluster. Analysis of spectra obtained using the Gas Imaging Spectrometer on ASCA shows nonaxisymmetric variations in both the temperature and iron abundance. Traveling west from the cluster center, the temperature increases to 9 keV at 20' and then decreases rapidly to 5 keV at 40'. There is a hot (>10 keV) region to the northwest of the cluster center. The abundance is approximately constant over much of the surveyed region, but there is evidence for an increased abundance in the northwest hot area and a gradual decrease in a westerly direction. C1 UNIV TOKYO,DEPT PHYS,BUNKYO KU,TOKYO 113,JAPAN. TOKYO METROPOLITAN UNIV,DEPT PHYS,HACHIOJI,TOKYO 19203,JAPAN. MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. NAGOYA UNIV,DEPT ASTROPHYS,CHIKUSA KU,NAGOYA,AICHI 46401,JAPAN. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. RP ARNAUD, KA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 24 TC 53 Z9 53 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP L67 EP L70 DI 10.1086/187634 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300016 ER PT J AU CORCORAN, MF WALDRON, WL MACFARLANE, JJ CHEN, W POLLOCK, AMT TORN, K KITAMOTO, S MIURA, N EGOSHI, M OHNO, Y AF CORCORAN, MF WALDRON, WL MACFARLANE, JJ CHEN, W POLLOCK, AMT TORN, K KITAMOTO, S MIURA, N EGOSHI, M OHNO, Y TI ASCA SOLID-STATE IMAGING SPECTROMETER OBSERVATIONS OF O-STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EARLY-TYPE; STARS, INDIVIDUAL (LAMBDA ORIONIS, DELTA ORIONIS); X-RAYS, STARS ID X-RAY-EMISSION; DRIVEN STELLAR WINDS; DELTA-ORIONIS-A; SUPER-GIANTS; ZETA-PUPPIS; HOT STARS; INSTABILITIES; CATALOG; MODEL AB We report ASCA Solid State Imaging Spectrometer (SIS) X-ray observations of the O stars delta Ori and lambda Ori. The energy resolution of the SIS allows us to resolve features in the O star X-ray spectra which are not apparent in spectra obtained by X-ray spectrometers with lower energy resolution. SIS spectra from both stars show evidence of line emission, suggesting the thermal nature of the X-ray source. However, the observed line strengths are different for the two stars. The observed stellar X-ray spectra are not well described by isothermal models although absorbed thermal emission models with two or more temperatures can provide an adequate fit to the data. For both stars we present evidence of absorbing columns significantly larger than the known ISM columns, indicative of absorption by a circumstellar medium, presumably the stellar winds. In addition, the lambda Ori spectrum shows the presence of emission at energies >3 keV which is not seen in the delta Ori spectrum. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. APPL RES CORP,LANDOVER,MD 20785. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV WISCONSIN,INST FUS TECHNOL,MADISON,WI 53706. COMP SCI CO LTD,SHEFFIELD S11 7EY,S YORKSHIRE,ENGLAND. OSAKA UNIV,FAC SCI,DEPT EARTH & SPACE SCI,TOYONAKA,OSAKA 560,JAPAN. RP CORCORAN, MF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 25 TC 38 Z9 38 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP L95 EP L98 DI 10.1086/187641 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300023 ER PT J AU DRAKE, SA SINGH, KP WHITE, NE SIMON, T AF DRAKE, SA SINGH, KP WHITE, NE SIMON, T TI ASCA X-RAY-SPECTRA OF THE ACTIVE SINGLE STARS BETA-CETI AND PI(1)-URSAE-MAJORIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ABUNDANCES; STARS, CORONAE; STARS, INDIVIDUAL (PHI-1 URSAE MAJORIS, BETA CETI); X-RAYS, STARS ID ELEMENTAL ABUNDANCES; SOLAR; EMISSION; OXYGEN; FLARE; NEON AB We present X-ray spectra obtained by ASCA of two single, active stars, the G dwarf pi(1) UMa, and the G9/KO giant beta Cet. The spectra of both stars require the presence of at least two plasma components with different temperatures, 0.3-0.4 keV and similar to 0.7 keV, in order for acceptable fits to be obtained. The spectral resolving power and signal-to-noise ratio of the SIS spectra allow us to formally constrain the coronal abundances of a number of elements. In beta Cet, we find Mg to be overabundant, while other elements such as O, Ne, and N are underabundant, relative to the solar photospheric values. From the lower signal-to-noise ratio SIS spectrum of pi(1) UMa, we find evidence for underabundances of O, Ne, and Fe. These results are discussed in the context of the present understanding of elemental abundances in solar and stellar coronae. C1 NASA,GODDARD SPACE FLIGHT CTR,USRA,GREENBELT,MD 20771. NASA,NRC,WASHINGTON,DC. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP DRAKE, SA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 668,GREENBELT,MD 20771, USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 21 TC 49 Z9 49 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP L87 EP L90 DI 10.1086/187639 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300021 ER PT J AU FABIAN, AC ARNAUD, KA BAUTZ, MW TAWARA, Y AF FABIAN, AC ARNAUD, KA BAUTZ, MW TAWARA, Y TI ASCA OBSERVATIONS OF COOLING FLOWS IN CLUSTERS OF GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COOLING FLOWS; GALAXIES, CLUSTERS OF ID RAY ABSORBING MATTER; STAR FORMATION; EMITTING GAS; ABELL-478 AB ASCA spectra of the central regions of three cooling flows, in the Perseus, Centaurus, and A1795 clusters, together with the spectrum of the center of the Coma Cluster, are studied. Absorbed, cooler and/or cooling components are required for the cooling flow spectra but not for that of the Coma Cluster. Problems have been encountered with the basic plasma emission models in the energy range of the iron L complex, which preclude further detailed analysis at present. Our results show the potential of ASCA data for revealing the structure of cooling flows. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. NAGOYA UNIV,DEPT ASTROPHYS,CHIKUSA KU,NAGOYA,AICHI 46401,JAPAN. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. RP FABIAN, AC (reprint author), UNIV CAMBRIDGE,INST ASTRON,MADINGLEY RD,CAMBRIDGE CB3 0HA,ENGLAND. NR 30 TC 90 Z9 90 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 NOV 20 PY 1994 VL 436 IS 1 BP L63 EP L66 DI 10.1086/187633 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300015 ER PT J AU GEORGE, IM NANDRA, K TURNER, TJ CELOTTI, A AF GEORGE, IM NANDRA, K TURNER, TJ CELOTTI, A TI THE X-RAY-SPECTRUM OF THE HIGHLY POLARIZED QUASAR PKS-1502+106 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; GALAXIES, NUCLEI; QUASARS, INDIVIDUAL (PKS 1502 + 106); RADIATION MECHANISM, NONTHERMAL; X-RAYS, GALAXIES ID EXTRAGALACTIC RADIO-SOURCES; ACTIVE GALACTIC NUCLEI; COMPLETE SAMPLE; RELATIVISTIC JETS; OBJECTS; BLAZARS; CATALOG; BRIGHT; GHZ; RADIATION AB We report the detection and spectrum of the distant (z = 1.839), highly polarized quasar PKS 1502 + 106 in the X-ray band based on data collected over the period 1990-1994 using ROSAT and ASCA. We find the source to exhibit intensity variations of a factor greater than or similar to 2 at 1 keV on timescales of years, small compared to the variability observed historically in the radio, millimeter, and optical bands. The (energy) spectral index is found in the range 0.4 less than or similar to alpha(X) less than or similar to 0.8 (at 90% confidence). Its multiwaveband spectral index is broadly consistent with other highly polarized quasars (HPQs). From the application of an inhomogeneous synchrotron self-Compton (SSC) jet we find that a model similar to that proposed for 3C 279 is consistent with the multiwaveband spectrum. We suggest that a change in the energy injection and/or transport mechanisms within such a jet could easily result in PKS 1502 + 106 being detectable at gamma-ray energies. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. UNIV CAMBRIDGE,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. RP GEORGE, IM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 668,GREENBELT,MD 20771, USA. NR 47 TC 11 Z9 11 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP L59 EP L62 DI 10.1086/187632 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300014 ER PT J AU GOTTHELF, EV JALOTA, L MUKAI, K WHITE, NE AF GOTTHELF, EV JALOTA, L MUKAI, K WHITE, NE TI AN ASCA OBSERVATION OF THE CASTOR SYSTEM SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, ECLIPSING; STARS, ABUNDANCES; STARS, FLARES; STARS, INDIVIDUAL (CASTOR, YY GEMINORUM) ID X-RAY-EMISSION; FLARE STARS; EXOSAT; SOLAR AB We report on a day-long ASCA broadband (1-10 keV) spectre-imaging observation of the X-ray emission from the Castor multibinary system. Significant flares were detected from both the flare star system YY Gem (Castor C) and from Castor AB located 73'' away. Using an optimal viewing geometry and image restoration techniques, we are able to spatially resolve the emission from the two X-ray components. Broadband flare activity from Castor AB is confirmed, and quiescent flux is detected. The quiescent spectrum of YY Gem is a complex blend of emission lines across the ASCA bandpass which requires multitemperature components or two-temperature variable metal-poor abundances (similar to 5-10 below solar) to obtain a satisfactory fit to both the Mewe-Kaastra and Raymond-Smith models. The flare spectrum is consistent with an increase in the emissivity of the hotter component. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 17 TC 17 Z9 17 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP L91 EP L94 DI 10.1086/187640 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300022 ER PT J AU LOEWENSTEIN, M MUSHOTZKY, RF TAMURA, T IKEBE, Y MAKISHIMA, K MATSUSHITA, K AWAKI, H SERLEMITSOS, PJ AF LOEWENSTEIN, M MUSHOTZKY, RF TAMURA, T IKEBE, Y MAKISHIMA, K MATSUSHITA, K AWAKI, H SERLEMITSOS, PJ TI DISCOVERY AND IMPLICATIONS OF VERY-LOW METAL ABUNDANCES IN NGC-1404 AND NGC-4374 SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GALAXIES, ABUNDANCES; GALAXIES, FORMATION; GALAXIES, INDIVIDUAL (NGC 1404, NGC 4374) ID EARLY-TYPE GALAXIES; ELLIPTIC GALAXIES; METALLICITY; GRADIENTS; IRON AB We present our analysis of ASCA PV phase observations of the elliptical galaxies NGC 1404 and NGC 4374 (M84). The average metallicities in the hot gas derived from the SIS spectra are exceptionally low, Z similar to 0.15 solar, while the temperatures are ''typical,'' kT similar to 0.75 keV. We also place upper limits on intrinsic column densities. The low abundances lend support to the theory of Fe enrichment of intracluster media by protogalactic Type II supernova-driven winds and raise the possibility of a fundamental connection between baryon fraction, dissipation, and abundances in elliptical galaxies. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. UNIV TOKYO,DEPT PHYS,TOKYO 113,JAPAN. KYOTO UNIV,DEPT PHYS,SAKYO KU,KYOTO 60601,JAPAN. RP LOEWENSTEIN, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. RI Tamura, Takayuki/K-8236-2012 NR 24 TC 58 Z9 58 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP L75 EP L78 DI 10.1086/187636 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300018 ER PT J AU MATSUSHITA, K MAKISHIMA, K AWAKI, H CANIZARES, CR FABIAN, AC FUKAZAWA, Y LOEWENSTEIN, M MATSUMOTO, H MIHARA, T MUSHOTZKY, RF OHASHI, T RICKER, GR SERLEMITSOS, PJ TSURU, T TSUSAKA, Y YAMAZAKI, T AF MATSUSHITA, K MAKISHIMA, K AWAKI, H CANIZARES, CR FABIAN, AC FUKAZAWA, Y LOEWENSTEIN, M MATSUMOTO, H MIHARA, T MUSHOTZKY, RF OHASHI, T RICKER, GR SERLEMITSOS, PJ TSURU, T TSUSAKA, Y YAMAZAKI, T TI DETECTIONS OF HARD X-RAY EMISSIONS FROM BRIGHT EARLY-TYPE GALAXIES WITH ASCA SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, CLUSTERS OF; GALAXIES, ELLIPTIC AND LENTICULAR, CD; X-RAYS, GALAXIES; X-RAYS, ISM ID VIRGO CLUSTER; SPECTRAL PROPERTIES; NGC-4472; GINGA; GAS AB Five bright elliptical galaxies in the Virgo Cluster, NGC 4365, NGC 4374 (M84), NGC 4406 (M86), NGC 4472 (M49), and NGC 4636, were observed with ASCA. In addition to the extended thermal X-ray emission of temperature kT similar to 1 keV, harder X-rays with color temperature kT greater than or equal to 2 keV were detected from all of them. The 2-10 keV luminosities of this hard component for the five galaxies, integrated within 5', are distributed within a relatively narrow range of (1-4) x 10(40) ergs s(-1). The hard X-ray component is primarily attributed to the integrated emission from discrete X-ray sources. In NGC 4406 and NGC 4374 the data indicate that the hard component is contributed additionally by foreground/background emission from the hot intracluster medium (ICM) of the Virgo Cluster. The hard component of NGC 4472 seems also contributed by the Virgo ICM emission, but in this case there is evidence that the ICM brightness is locally enhanced within similar to 10' of NGC 4472. C1 KYOTO UNIV,DEPT PHYS,SAKYO KU,KYOTO 60601,JAPAN. MIT,CTR SPACE RES,CAMBRIDGE,MA 02193. UNIV CAMBRIDGE,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,GREENBELT,MD 20771. INST PHYS & CHEM RES,COSM RAY LAB,WAKO 35001,SAITAMA,JAPAN. TOKYO METROPOLITAN UNIV,DEPT PHYS,HACHIOJI,TOKYO 19203,JAPAN. NAGOYA UNIV,DEPT PHYS,CHIKUSA KU,NAGOYA,AICHI 46401,JAPAN. RP MATSUSHITA, K (reprint author), UNIV TOKYO,DEPT PHYS,BUNKYO KU,HONGO 7-3-1,TOKYO 113,JAPAN. RI Mihara, Tatehiro/C-5536-2017 OI Mihara, Tatehiro/0000-0002-6337-7943 NR 23 TC 89 Z9 89 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 NOV 20 PY 1994 VL 436 IS 1 BP L41 EP L45 DI 10.1086/187628 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300010 ER PT J AU MUSHOTZKY, RF LOEWENSTEIN, M AWAKI, H MAKISHIMA, K MATSUSHITA, K MATSUMOTO, H AF MUSHOTZKY, RF LOEWENSTEIN, M AWAKI, H MAKISHIMA, K MATSUSHITA, K MATSUMOTO, H TI ASCA OBSERVATION OF NGC-4636 - DARK-MATTER AND METALLICITY GRADIENT SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GALAXIES, ABUNDANCES; GALAXIES, FORMATION; GALAXIES, INDIVIDUAL (NGC 4636) ID EARLY-TYPE GALAXIES; ELLIPTIC GALAXIES; IRON AB We present our analysis of ASCA PV phase observation of the elliptical galaxy NGC 4636. SIS spectra in six concentric annuli centered on NGC 4636 are used to derive temperature, metallicity, and column density profiles for the hot interstellar medium. Outside of the central 3' the temperature is roughly constant at similar to 0.85 keV, while the metallicity decreases from >0.36 solar at the center to <0.12 solar at R similar to 9'. The implications of this gradient for elliptical galaxy formation and the enrichment of intracluster gas are discussed. We derive a detailed mass profile consistent with the stellar velocity dispersion and with ROSAT PSPC and ASCA SIS X-ray temperature profiles. We find that NGC 4636 becomes dark matter dominated at roughly the de Vaucouleurs radius, and, at r similar to 100 kpc, the ratio of dark to luminous matter density is similar to 80 and M./L. approximate to 150. Evidence for the presence of a cooling flow is also discussed. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. KYOTO UNIV,DEPT PHYS,SAKYO KU,KYOTO 60601,JAPAN. UNIV TOKYO,DEPT PHYS,TOKYO 113,JAPAN. RP MUSHOTZKY, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. NR 25 TC 48 Z9 48 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 NOV 20 PY 1994 VL 436 IS 1 BP L79 EP L82 DI 10.1086/187637 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300019 ER PT J AU NOUSEK, JA BALUTA, CJ CORBET, RHD MUKAI, K OSBORNE, JP ISHIDA, M AF NOUSEK, JA BALUTA, CJ CORBET, RHD MUKAI, K OSBORNE, JP ISHIDA, M TI ASCA OBSERVATIONS OF SS CYGNI DURING AN ANOMALOUS OUTBURST SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; NOVAE, CATACLYSMIC VARIABLES; X-RAYS, STARS ID ACCRETION DISK AB SS Cygni was observed by the ASCA satellite on 1993 May 27, the first catalysmic variable studied by ASCA. The observations were conducted while the system was in an outburst of the ''anomalous'' variety. The SIS spectrum cannot be explained by two-temperature Raymond-Smith coronal plasma models as invoked in previous studies with lower spectral resolution. Significantly better agreement is found for models with plasma emission at kT = 0.8, 3.5 keV and thermal bremsstrahlung at kT = 18 keV. The GIS data are consistent with the SIS data, showing evidence for Fe line emission but showing no evidence of pulsation over times ranging from seconds to minutes. These observations seem at variance with standard theory in two regards: we simultaneously see hard X-rays and optically thin soft X-rays while the system is in outburst, and we see a nonsmooth emission measure distribution. We speculate on possible scenarios which might resolve these differences. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV LEICESTER,DEPT PHYS & ASTRON,LEICESTER LE1 7RH,LEICS,ENGLAND. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. RP NOUSEK, JA (reprint author), PENN STATE UNIV,DEPT ASTRON & ASTROPHYS,525 DAVEY LAB,UNIVERSITY PK,PA 16802, USA. NR 14 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP L19 EP L22 DI 10.1086/187623 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300005 ER PT J AU PTAK, A YAQOOB, T SERLEMITSOS, PJ MUSHOTZKY, R OTANI, C AF PTAK, A YAQOOB, T SERLEMITSOS, PJ MUSHOTZKY, R OTANI, C TI RAPID X-RAY SPECTRAL VARIABILITY IN NGC-3227 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC 3227); GALAXIES, SEYFERT; X-RAYS, GALAXIES ID MCG-6-30-15; GALAXIES AB We present preliminary results of an ASCA observation of the Seyfert 1 galaxy, NGC 3227. The source exhibits rapid X-ray amplitude and spectral variability, the flux below 2 keV varying by a factor of similar to 3 in similar to 10,000 s while the flux in the 2-10 keV band varies by a factor of similar to 2 in the same interval. The spectrum below similar to 1 keV shows complex structure compared to a simple power-law model. We argue that the simplest interpretation of the spectrum is in terms of a power-law continuum modified by absorption in a photoionized medium. Simple, static, ionized absorber models yield an ionization parameter of similar to 0.05 and column density similar to 3.6 x 10(21) cm(-2). However, the data strongly indicate that the situation is much more complex than this. If the spectral variability is caused by a changing ionization state of the absorber, then both the ionization state and column density are required to decrease as the intrinsic source luminosity increases. This does not have a simple physical interpretation. On the other hand, the data are also consistent with the spectral variability being due to changes in the intrinsic power-law index with little change in the ionization state of the absorber. This case could correspond to an absorber which is always in some average ionization state and the continuum variability is too fast for the absorber to deviate significantly from that, or the absorber could be in the form of an X-ray-heated wind. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. RI Otani, Chiko/A-6510-2016 NR 14 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 NOV 20 PY 1994 VL 436 IS 1 BP L31 EP L34 DI 10.1086/187626 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300008 ER PT J AU VRTILEK, SD MIHARA, T PRIMINI, FA KAHABKA, P MARSHALL, H AGERER, F CHARLES, PA CHENG, FH DENNERL, K LADOUS, C HU, EM RUTTEN, R SERLEMITSOS, P SOONG, Y STULL, J TRUMPER, J VOGES, W WAGNER, RM WILSON, R AF VRTILEK, SD MIHARA, T PRIMINI, FA KAHABKA, P MARSHALL, H AGERER, F CHARLES, PA CHENG, FH DENNERL, K LADOUS, C HU, EM RUTTEN, R SERLEMITSOS, P SOONG, Y STULL, J TRUMPER, J VOGES, W WAGNER, RM WILSON, R TI MULTIWAVELENGTH OBSERVATIONS OF HERCULES X-1/HZ HERCULIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; PULSARS, INDIVIDUAL (HERCULES X-1) ID X-RAY; LOW STATE; PERIOD AB We present first results from a multiwavelength campaign to observe the binary pulsar system Her X-1/HZ Her. The campaign spanned 4 days during 1993 August: observations were taken with five satellites (IUE, EUVE, ROSAT, ASCA, and CGRO/BATSE) and several ground-based facilities. A substantial, unexpected drop in flux at X-ray energies, with no change in absorbing column density, was observed. The pulse period has increased from the previous measurement, contrary to the usual spin-up, and no pulsed emission is detected above 0.9 keV in the low state. The optical and UV fluxes continued to show 1.7 day modulation attributed to X-ray heating of the companion star. However, the significant reduction in UV flux observed around eclipse implies an absence of the normally observed excess attributed to X-ray heating of the disk. We conclude that we have observed an anomalous low state, seen only once before (Parmar et al. 1985), in which the X-ray flux is not redistributed but obscured. We suggest explanations for the behavior of the flux at different wavelengths. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. INST PHYS & CHEM RES,WAKO,SAITAMA 35101,JAPAN. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. EUREKA SCI INC,OAKLAND,CA 94602. UNIV OXFORD,DEPT PHYS,OXFORD OX1 3RH,ENGLAND. ESA,IUE OBSERV,E-28080 MADRID,SPAIN. INST ASTRON,HONOLULU,HI 96822. ROYAL GREENWICH OBSERV,NFRA,E-38780 LA PALMA,SPAIN. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. ALFRED UNIV,ALFRED,NY 14802. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP VRTILEK, SD (reprint author), CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. RI Mihara, Tatehiro/C-5536-2017; OI Mihara, Tatehiro/0000-0002-6337-7943; Primini, Francis/0000-0002-6077-0643 NR 26 TC 42 Z9 42 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 NOV 20 PY 1994 VL 436 IS 1 BP L9 EP L13 DI 10.1086/187621 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300003 ER PT J AU WEAVER, KA YAQOOB, T HOLT, SS MUSHOTZKY, RF MATSUOKA, M YAMAUCHI, M AF WEAVER, KA YAQOOB, T HOLT, SS MUSHOTZKY, RF MATSUOKA, M YAMAUCHI, M TI NEW X-RAY SPECTRAL OBSERVATIONS OF NGC-4151 WITH ASCA SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL, NGC 4151); GALAXIES, NUCLEI; GALAXIES, SEYFERT ID NGC-4151; ABSORPTION AB We present new X-ray spectral data for the well-studied Seyfert galaxy NGC 4151, which was observed twice for about 20 ks each during the ASCA performance verification phase, once on 1993 May 25 and again on 1993 November 5. The source underwent complex spectral variability, and the observed 2-10 keV flux increased by a factor of 2 while the intrinsic 2-10 keV flux increased by no more than 20%. The data can be modeled with either a dual cold absorber plus a soft X-ray excess consisting of scattered continuum flux and an additional ''ultrasoft'' X-ray excess component, or a warm absorber plus scattered continuum flux. There is evidence for variability at <1 keV energies that is unrelated to the 2-10 keV continuum. For an ionized-absorber description of NGC 4151, changes in the ionization state of the absorber appear to be unrelated to changes in the ionizing continuum. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INST PHYS & CHEM RES,WAKO,SAITAMA 35101,JAPAN. RP WEAVER, KA (reprint author), PENN STATE UNIV,DEPT ASTRON & ASTROPHYS,525 DAVEY LAB,UNIVERSITY PK,PA 16802, USA. NR 17 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 1994 VL 436 IS 1 BP L27 EP L30 DI 10.1086/187625 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300007 ER PT J AU WOO, JW CLARK, GW DAY, CSR NAGASE, F TAKESHIMA, T AF WOO, JW CLARK, GW DAY, CSR NAGASE, F TAKESHIMA, T TI MEASUREMENTS OF THE GRAIN-SCATTERED X-RAY HALOS OF ECLIPSING MASSIVE X-RAY BINARIES - VELA X-1 AND CENTAURUS X-3 SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, ECLIPSING; DUST, EXTINCTION; PULSARS, INDIVIDUAL (VELA X-1, CENTAURUS X-3); X-RAYS, STARS ID INTERSTELLAR GRAINS AB We have measured the decaying dust-scattered X-ray halo of Cen X-3 during its binary eclipse with the ASCA solid-state imaging spectrometer (SIS). The surface brightness profile (SBP) of the image in the low-energy band (0.5-3 keV) lies substantially above the point-spread function (PSF) of the X-ray telescope, while the SBP in the high-energy band (5-10 keV) exhibits no significant deviation. By contrast, the SBPs of Vela X-l during its eclipse are consistent with the PSF in both the low- and high-energy bands-strong evidence that a dust halo is indeed present in Cen X-3. Accordingly, we modeled the SBP of Cen X-3 taken from six consecutive time segments under the principal assumptions that the dust is distributed uniformly along a segment of the line of sight, the grains have a power-law size distribution, and the low-energy source flux was the same function of orbital phase before as during our observation. The best-fit set of parameters included a grain density value of 1.3 g cm(-3), substantially less than the density of ''astronomical silicate.'' This result supports the idea that interstellar grains are ''fluffy'' aggregates of smaller solid particles. We attribute the failure to detect a halo of Vela X-1 during its eclipse phase to extended strong circumsource absorption that probably occurred before the eclipse and allowed the halo to decay away before the observation began. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. INST PHYS & CHEM RES,WAKO,SAITAMA 35101,JAPAN. RP WOO, JW (reprint author), MIT,CTR SPACE RES,CAMBRIDGE,MA 02139, USA. NR 16 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 NOV 20 PY 1994 VL 436 IS 1 BP L5 EP L8 DI 10.1086/187620 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PR933 UT WOS:A1994PR93300002 ER PT J AU JAMES, ME AF JAMES, ME TI THE PATHFINDER AVHRR LAND DATA SET SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Editorial Material RP JAMES, ME (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GLOBAL CHANGE DATA CTR,CODE 902-3,GREENBELT,MD 20771, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 1994 VL 15 IS 17 BP 3315 EP 3316 PG 2 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PX956 UT WOS:A1994PX95600001 ER PT J AU MAIDEN, ME GRECO, S AF MAIDEN, ME GRECO, S TI NASA PATHFINDER DATA SET PROGRAM - LAND-SURFACE PARAMETERS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID MICROWAVE BRIGHTNESS TEMPERATURES AB The Pathfinder data set concept was initiated by the Earth Observing System (EOS) Program Office at the National Aeronautics and Space Administration (NASA) Headquarters to address how existing satellite-derived data sets could be used for global change research prior to the availability of EOS data. They are defined as long time-series satellite data sets capable of stable calibration which can be reprocessed using a community-consensus set of algorithms. In October 1990 NASA and the National Oceanic and Atmospheric Administration (NOAA) initiated a joint Pathfinder program. Data from three NOAA and one Defense Meterological Satellite Program (DMSP) instruments have been designated as Pathfinders under this activity. In addition to this joint effort, NASA has also initiated a Pathfinder development effort for data from both Landsat and the Scanning Multichannel Microwave Radiometer (SMMR) flown on NASA's Nimbus-7 satellite. The AVHRR Pathfinder was the first set of projects to be initiated. Because the data have distinct disciplinary user heritages and expertise associated with the atmosphere, ocean, and land, three separate Science Working Groups were formed to recommend and comment on all stages of data set design and development. One of these groups is the AVHRR Land Pathfinder Science Working Group. Additionally, low resolution land surface parameters will be produced by the SSM/I and SMMR Pathfinder projects. A Global 1 km Data Set Project, in the spirit of Pathfinder and partially funded with NASA Pathfinder funding, was begun in October 1991 and began collecting data continuously on a daily basis on 1 April 1992. One of the goals of Pathfinder data set production, to make available consistent long-time series data sets for global change research, has encouraged substantial interdisciplinary use of the data, and therefore consideration of problems of data fusion or integration. Work in producing the Pathfinder data sets has exposed important technical problems which scientists encounter impeding interuse of data sets. Presently, an experiment involving scientists and systems engineers working with several Pathfinder data sets is exploring possible solutions to some of these technical problems. C1 SM SYST RES CORP,WASHINGTON,DC. RP MAIDEN, ME (reprint author), NASA,HEADQUARTERS,CODE YDD,WASHINGTON,DC 20546, USA. NR 21 TC 16 Z9 16 U1 0 U2 0 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 1994 VL 15 IS 17 BP 3333 EP 3345 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PX956 UT WOS:A1994PX95600004 ER PT J AU JAMES, ME KALLURI, SNV AF JAMES, ME KALLURI, SNV TI THE PATHFINDER AVHRR LAND DATA SET - AN IMPROVED COARSE RESOLUTION DATA SET FOR TERRESTRIAL MONITORING SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID RADIOMETER INFRARED CHANNELS; VEGETATION INDEX; CALIBRATION; DEGRADATION; NOAA-7; CO2 AB A reprocessing of 12 years of global data from the Advanced Very High Resolution Radiometers on board the afternoon-viewing NOAA series satellites (NOAA-7, 9, and 11) is taking place as part of the NASA/NOAA Pathfinder project. A Pathfinder AVHRR land data set is being produced which is composed of global, 8 km NDVI with associated reflectances, brightness temperatures, solar and scan geometry, and cloud estimation. This data set is being processed using the best available methods in order to produce a consistent time series of data of unprecedented quality. Methods used in processing include a cross-satellite calibration, navigation using an orbital model and updated ephemerides, and correction for Rayleigh scattering. The data will be available to the community as both daily and composite data and analysis of this long time series is expected to provide insight into terrestrial processes, seasonal and annual variability, and methods for handling large volume data sets. C1 UNIV MARYLAND,DEPT GEOG,GLOBAL REMOTE SENSING LAB,COLLEGE PK,MD 20742. RP JAMES, ME (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CTR GLOBAL CHANGE DATA,CODE 902-3,GREENBELT,MD 20771, USA. NR 29 TC 355 Z9 394 U1 4 U2 18 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 1994 VL 15 IS 17 BP 3347 EP 3363 PG 17 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PX956 UT WOS:A1994PX95600005 ER PT J AU LOS, SO JUSTICE, CO TUCKER, CJ AF LOS, SO JUSTICE, CO TUCKER, CJ TI A GLOBAL 1-DEGREES-BY-1-DEGREES NDVI DATA SET FOR CLIMATE STUDIES DERIVED FROM THE GIMMS CONTINENTAL NDVI DATA SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID DIFFERENCE VEGETATION INDEX; SIMPLE BIOSPHERE MODEL; GENERAL-CIRCULATION MODELS; HIGH-RESOLUTION RADIOMETER; NOAA-AVHRR DATA; NEAR-IR BANDS; SATELLITE DATA; CANOPY REFLECTANCE; METEOROLOGICAL SATELLITE; RED AB A nine-year (1982-1990) global normalized difference vegetation index (NDVI) data set with a spatial resolution of 1-degrees by 1-degrees and a temporal resolution of one month was compiled for use in climate studies. This data set was derived from higher resolution (5-8 km) monthly continental NDVI data sets that have been processed and archived by the Global Inventory Monitoring and Modelling Studies (GIMMS) group at NASA/Goddard Space Flight Center. The continental GIMMS NDVI data sets were calculated from Global Area Coverage (GAC) data collected at daily intervals by the Advanced Very High Resolution Radiometer (AVHRR) onboard the NOAA-7, -9 and -11 satellites. The global 1-degrees by 1-degrees NDVI data set was produced to calculate land surface parameters for use within general circulation model J of the atmosphere (GCM). In view of this quantitative application, an evaluation is given of the representation by the NDVI data of the spectral properties of vegetation at the landsurface. Errors are defined as deviations from measurements obtained under standard conditions, i.e., conditions at the-top-of-the-atmosphere with no clouds, clear atmosphere, near-nadir viewing angles, overhead Sun, and invariant soil background. The discussion includes an assessment of (1) the data collected and processed onboard the AVHRR; (2) processing of the AVHRR data into the continental GIMMS NDVI data sets; (3) resampling of the continental data sets to a 1-degrees by 1-degrees data set; and (4) propagation of inconsistencies and biases from (1), (2) and (3) into the 1-degrees by 1-degrees global NDVI data. Examples are shown of the temporal and spatial variations in spectral properties of vegetation contained in the 1-degrees by 1-degrees NDVI data, and these are compared with the dynamics of biophysical parameters derived from land cover classes that were used in previous climate studies. C1 UNIV MARYLAND,GLOBAL REMOTE SENSING,COLLEGE PK,MD 20742. RP LOS, SO (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771, USA. RI Los, Sietse/G-8985-2012 NR 79 TC 185 Z9 213 U1 0 U2 10 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 1994 VL 15 IS 17 BP 3493 EP 3518 PG 26 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PX956 UT WOS:A1994PX95600012 ER PT J AU SELLERS, PJ TUCKER, CJ COLLATZ, GJ LOS, SO JUSTICE, CO DAZLICH, DA RANDALL, DA AF SELLERS, PJ TUCKER, CJ COLLATZ, GJ LOS, SO JUSTICE, CO DAZLICH, DA RANDALL, DA TI A GLOBAL 1-DEGREES-BY-1-DEGREES NDVI DATA SET FOR CLIMATE STUDIES .2. THE GENERATION OF GLOBAL FIELDS OF TERRESTRIAL BIOPHYSICAL PARAMETERS FROM THE NDVI SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SIMPLE BIOSPHERE MODEL; VEGETATION INDEXES; CANOPY REFLECTANCE; CIRCULATION MODELS; PHOTOSYNTHESIS; TRANSPIRATION; RADIATION; SATELLITE; LENGTH; AVHRR AB A satellite-based 1-degrees by 1-degrees normalized difference vegetation index (NDVI) data set has been processed to derive land surface parameters for general circulation models of the atmosphere (GCMs). Prior to calculation of the land surface parameters, corrections were applied to the source NDVI data set to account for (i) obvious anomalies in the data time-series, (ii) the effect of variations in solar zenith angle, (iii) data dropouts in cold regions where a temperature threshold procedure designed to screen for clouds also eliminates cold land surface points, and (iv) persistent cloud cover in the tropics. An outline of the procedures for calculating land surface parameters from the corrected NDVI data set is given, and a brief description is provided of source material that was used in addition to the NDVI data. The data sets summarized in this paper should represent improvements over prescriptions currently used in land surface parameterizations in that the spatial and temporal dynamics of key land surface parameters, in particular of those related to vegetation, are obtained from direct measurements rather than indirectly inferred from survey-based land cover classifications. C1 UNIV MARYLAND,GLOBAL REMOTE SENSING LAB,COLLEGE PK,MD 20742. COLORADO STATE UNIV,DEPT ATMOSPHER SCI,FT COLLINS,CO 80523. RP SELLERS, PJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,CODE 923,GREENBELT,MD 20771, USA. RI collatz, george/D-5381-2012; Los, Sietse/G-8985-2012; Randall, David/E-6113-2011 OI Randall, David/0000-0001-6935-4112 NR 39 TC 357 Z9 409 U1 2 U2 33 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 1994 VL 15 IS 17 BP 3519 EP 3545 PG 27 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PX956 UT WOS:A1994PX95600013 ER PT J AU TUCKER, CJ NEWCOMB, WW DREGNE, HE AF TUCKER, CJ NEWCOMB, WW DREGNE, HE TI AVHRR DATA SETS FOR DETERMINATION OF DESERT SPATIAL EXTENT SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID DIFFERENCE VEGETATION INDEX; NOAA-AVHRR; CANOPY REFLECTANCE; AEROSOL LAYER; CALIBRATION; SAHEL; RAINFALL; PHOTOSYNTHESIS; TRANSPIRATION; SOIL AB A programme of global arid and semi-arid land monitoring is currently underway at NASA/Goddard Space Flight Center using meterological satellite data to detect possible climatic change as manifested by changes in arid and semi-arid land extent. This has resulted in the processing and interpretation of a large amount of satellite data from the NOAA-series of polar-orbiting satellites. Techniques are described and preliminary results presented for determination of the boundary between the Sahara Desert and the Sahel Zone of Africa using daily advanced very high resolution radiometer data from 1980-1992. Some of the techniques may be of interest to other researchers who are will be using large multi-year data sets derived from coarse-resolution satellite data to investigate large-scale land surface questions. C1 TEXAS TECH UNIV,LUBBOCK,TX 79409. RP TUCKER, CJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,CODE 923,GREENBELT,MD 20771, USA. NR 54 TC 70 Z9 90 U1 1 U2 12 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 1994 VL 15 IS 17 BP 3547 EP 3565 PG 19 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PX956 UT WOS:A1994PX95600014 ER PT J AU RUNNING, SW JUSTICE, CO SALOMONSON, V HALL, D BARKER, J KAUFMANN, YJ STRAHLER, AH HUETE, AR MULLER, JP VANDERBILT, V WAN, ZM TEILLET, P CARNEGGIE, D AF RUNNING, SW JUSTICE, CO SALOMONSON, V HALL, D BARKER, J KAUFMANN, YJ STRAHLER, AH HUETE, AR MULLER, JP VANDERBILT, V WAN, ZM TEILLET, P CARNEGGIE, D TI TERRESTRIAL REMOTE-SENSING SCIENCE AND ALGORITHMS PLANNED FOR EOS MODIS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID DIFFERENCE VEGETATION INDEX; CONTERMINOUS UNITED-STATES; LAND-COVER CLASSIFICATION; SATELLITE DATA; AVHRR DATA; BIDIRECTIONAL REFLECTANCE; CANOPY REFLECTANCE; GLOBAL VEGETATION; BIOME MODEL; SNOW AB The Moderate Resolution Imaging Spectroradiometer (MODIS) will be the primary daily global monitoring sensor on the NASA Earth Observing System (EOS) satellites, scheduled for launch on the EOS-AM platform in June 1998 and the EOS-PM platform in December 2000. MODIS is a 36 channel radiometer covering 0.415-14.235 mum wavelengths, with spatial resolution from 250 m to 1 km at nadir. MODIS will be the primary EOS sensor for providing data on terrestrial biospheric dynamics and process activity. This paper presents the suite of global land products currently planned for EOSDIS implementation, to be developed by the authors of this paper, the MODIS land team (MODLAND). These include spectral albedo, land cover, spectral vegetation indices, snow and ice cover, surface temperature and fire, and a number of biophysical variables that will allow computation of global carbon cycles, hydrologic balances and biogeochemistry of critical greenhouse gases. Additionally, the regular global coverage of these variables will allow accurate surface change detection, fundamental determinant of global change. C1 UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. BOSTON UNIV,CTR REMOTE SENSING,BOSTON,MA 02215. UNIV ARIZONA,DEPT SOIL & WATER SCI,TUCSON,AZ 85721. UNIV LONDON UNIV COLL,DEPT PHOTOGRAMMETRY & SURVEYING,LONDON WC1E 6BT,ENGLAND. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF SANTA BARBARA,COMP SYST LAB,CRSEO,SANTA BARBARA,CA 93106. CANADA CTR REMOTE SENSING,OTTAWA,ON K1A 0Y7,CANADA. USDI,GEOL SURVEY,EROS DATA CTR,SIOUX FALLS,SD 57198. RP RUNNING, SW (reprint author), UNIV MONTANA,SCH FORESTRY,MISSOULA,MT 59812, USA. RI Hall, Dorothy/D-5562-2012 NR 68 TC 232 Z9 248 U1 2 U2 33 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 1994 VL 15 IS 17 BP 3587 EP 3620 PG 34 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PX956 UT WOS:A1994PX95600016 ER PT J AU KOSHAK, WJ BAILEY, J CHRISTIAN, HJ MACH, DM AF KOSHAK, WJ BAILEY, J CHRISTIAN, HJ MACH, DM TI AIRCRAFT ELECTRIC-FIELD MEASUREMENTS - CALIBRATION AND AMBIENT FIELD RETRIEVAL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID THUNDERSTORMS AB An aircraft locally distorts the ambient thundercloud electric field. In order to determine the field in the absence of the aircraft, an aircraft calibration is required. In this work a matrix inversion method is introduced for calibrating an aircraft equipped with four or more electric field sensors and a high-voltage corona point that is capable of charging the aircraft. An analytic, closed form solution for the estimate of a (3 x 3) aircraft calibration matrix is derived, and an absolute calibration experiment is used to improve the relative magnitudes of the elements of this matrix. To demonstrate the calibration procedure, we analyze actual calibration data derived from a Lear jet 28/29 that was equipped with five shutter-type field mill sensors (each with sensitivities of better than 1 V/m) located on the top, bottom, port, starboard, and aft positions. As a test of the calibration method, we analyze computer-simulated calibration data (derived from known aircraft and ambient fields) and explicitly determine the errors involved in deriving the variety of calibration matrices. We extend our formalism to arrive at an analytic solution for the ambient field, and again carry all errors explicitly. C1 UNIV ALABAMA, JOHNSON RES INST, HUNTSVILLE, AL 35812 USA. RP KOSHAK, WJ (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, DIV EARTH SYST SCI, MAIL STOP ES43, HUNTSVILLE, AL 35812 USA. NR 13 TC 7 Z9 7 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 20 PY 1994 VL 99 IS D11 BP 22781 EP 22792 DI 10.1029/94JD01682 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PT032 UT WOS:A1994PT03200004 ER PT J AU TEGEN, I FUNG, I AF TEGEN, I FUNG, I TI MODELING OF MINERAL DUST IN THE ATMOSPHERE - SOURCES, TRANSPORT, AND OPTICAL-THICKNESS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; SIZE DISTRIBUTIONS; AEROSOL-PARTICLES; WIND EROSION; SAHARAN DUST; DESERT DUST; SOILS; SIMULATIONS; CLIMATE; SCHEME AB A global three-dimensional model of the atmospheric mineral dust cycle is developed for the study of its impact on the radiative balance of the atmosphere. The model includes four size classes of mineral dust, whose source distributions are based on the distributions of vegetation, soil texture and soil moisture. Uplift and deposition are parameterized using analyzed winds and rainfall statistics that resolve high-frequency events. Dust transport in the atmosphere is simulated with the tracer transport model of the Goddard Institute for Space Studies. The simulated seasonal variations of dust concentrations show general reasonable agreement With the observed distributions, as do the size distributions at several observing sites. The discrepancies between the simulated and the observed dust concentrations point to regions of significant land surface modification. Monthly distribution of aerosol optical depths are calculated from the distribution of dust particle sizes. The maximum optical depth due to dust is 0.4-0.5 in the seasonal mean. The main uncertainties, about a factor of 3-5, in calculating optical thicknesses arise from the crude resolution of soil particle sizes, from insufficient constraint by the total dust loading in the atmosphere, and from our ignorance about adhesion, agglomeration, uplift, and size distributions of fine dust particles (< 1 mu m). C1 UNIV VICTORIA, SCH EARTH & OCEAN SCI, VICTORIA V8W 2Y2, BC, CANADA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. RP TEGEN, I (reprint author), COLUMBIA UNIV, DEPT APPL PHYS, NEW YORK, NY 10025 USA. NR 46 TC 462 Z9 500 U1 9 U2 62 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 20 PY 1994 VL 99 IS D11 BP 22897 EP 22914 DI 10.1029/94JD01928 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PT032 UT WOS:A1994PT03200012 ER PT J AU REMSBERG, EE BHATT, PP ECKMAN, RS GORDLEY, LL RUSSELL, JM SISKIND, DE AF REMSBERG, EE BHATT, PP ECKMAN, RS GORDLEY, LL RUSSELL, JM SISKIND, DE TI EFFECT OF THE HITRAN-92 SPECTRAL DATA ON THE RETRIEVAL OF NO2 MIXING RATIOS FROM NIMBUS-7 LIMS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INFRARED MONITOR; NITROGEN-DIOXIDE; STRATOSPHERIC OZONE; ODD NITROGEN; VALIDATION; ATMOSPHERE; HNO3 AB To ensure spectral consistency when comparing Nimbus 7 LIMS NO2 distributions with those from ATMOS and UARS, 1 day (May 5, 1979) of LIMS measurements were reprocessed using the NO2 line list on the HITRAN 92 tape compiled by AFGL. The revised NO2 mixing ratios are smaller by up to 20%. The decrease is not constant with height, latitude, or time of day but depends on the absolute amount of NO2 in the profile, as a result of a change in the degree of saturation for the strong NO2 spectral lines. The revised NO2 agrees better with correlative measurements and with NO2 distributions from the SAGE and HALOE satellite experiments but not with those from ATMOS 85. Profiles of the day/night ratio of revised NO2 are now larger near 5 hPa. There is also some improvement between observed and modeled ozone in the upper stratosphere, when the revised nighttime NO2 profile is used as the estimate of NOy for the model calculations. C1 SCI APPLICAT INT CORP, HAMPTON, VA 23666 USA. USN, RES LAB, WASHINGTON, DC 20375 USA. G & A TECH SOFTWARE INC, HAMPTON, VA 23666 USA. RP REMSBERG, EE (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. NR 38 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 20 PY 1994 VL 99 IS D11 BP 22965 EP 22973 DI 10.1029/94JD02042 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PT032 UT WOS:A1994PT03200018 ER PT J AU REMSBERG, EE BHATT, PP MILES, T AF REMSBERG, EE BHATT, PP MILES, T TI AN ASSESSMENT OF SATELLITE TEMPERATURE DISTRIBUTIONS USED TO DERIVE THE NET DIABATIC TRANSPORT FOR ZONALLY AVERAGED MODELS OF THE MIDDLE ATMOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LIMB INFRARED MONITOR; GENERAL-CIRCULATION STATISTICS; NORTHERN HEMISPHERE; NIMBUS-7 SAMS; METEOROLOGICAL ROCKETSONDE; STRATOSPHERIC TEMPERATURE; SEMIANNUAL OSCILLATION; RADIATIVE BALANCE; COOLING RATES; OZONE DATA AB Determinations of the zonally averaged and diabatically derived residual mean circulation (RMC) are particularly sensitive to the assumed zonal mean temperature distribution used as input. Several different middle atmosphere satellite temperature distributions have been employed in models and are compared here: a 4-year (late 1978 to early 1982) National Meteorological Center (NMC) climatology, the Barnett and Corney (or BC) climatology, and the 7 months of Nimbus 7 limb infrared monitor of the stratosphere (LIMS) temperatures. All three climatologies are generally accurate below the 10 hPa level, but there are systematic differences between them of up to +/-5 K in the upper stratosphere and lower mesosphere. The NMC/LIMS differences are evaluated using time series of rocketsonde and reconstructed satellite temperatures at station locations. Much of those biases can be explained by the differing vertical resolutions for the satellite-derived temperatures; the time series of reconstructed LIMS profiles have higher resolution and are more accurate. Because the LIMS temperatures are limited to just two full seasons, one cannot obtain monthly RMCs from them for an annual model calculation. Two alternate monthly climatologies are examined briefly: the 4-year Nimbus 7 stratospheric and mesospheric sounder (SAMS) temperatures and for the mesosphere the distribution from the Solar Mesosphere Explorer (SME), both of which are limb viewers of medium vertical resolution. There are also differences of the order of +/-5 K for those data sets. It is concluded that a major source of error in the determination of diabatic RMCs is a persistent pattern of temperature bias whose characteristics vary according to the vertical resolution of each individual climatology. C1 HUGHES STX CORP, GREENBELT, MD 20770 USA. SCI APPLICAT INT CORP, HAMPTON, VA 23666 USA. RP REMSBERG, EE (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. NR 83 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 20 PY 1994 VL 99 IS D11 BP 23001 EP 23017 DI 10.1029/94JD01953 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PT032 UT WOS:A1994PT03200021 ER PT J AU FOLKINS, I WEINHEIMER, AJ BRASSEUR, G LEFEVRE, F RIDLEY, BA WALEGA, JG COLLINS, JE PUESCHEL, RF AF FOLKINS, I WEINHEIMER, AJ BRASSEUR, G LEFEVRE, F RIDLEY, BA WALEGA, JG COLLINS, JE PUESCHEL, RF TI 3-DIMENSIONAL MODEL INTERPRETATION OF NOX MEASUREMENTS FROM THE LOWER STRATOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SULFATE AEROSOLS; CHEMISTRY; DIOXIDE; ACID AB A three-dimensional off-line chemistry transport model, driven by European Centre for Medium-Range Weather Forecasts winds and temperatures, is used to interpret measurements of NO and NO2 taken from the DC-8 during the second Airborne Arctic Stratospheric Expedition. The model was run in three configurations: gas phase chemistry alone, inclusion of the N2O5 aerosol reaction, and inclusion of both N2O5 and ClONO2 aerosol reactions. The run including the N2O5 aerosol reaction alone usually agreed best with measured NOx/NOy ratios in midlatitude air masses. The NOx/NOy ratios of the run with both aerosol reactions were always too low, while the gas phase ratios were usually too high, especially during March. All three simulations generated extremely low NO2/NOy ratios in air parcels that had spent several days or more in the polar night. Measured NO2/NOy ratios in these types of air masses were sometimes equally low but could also be considerably higher. Observed NO/NO2 ratios differed strongly from known theory. C1 SCI & TECHNOL CORP, HAMPTON, VA 23666 USA. CTR NATL RECH METEOROL, METEO FRANCE, TOULOUSE, FRANCE. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. NR 22 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 20 PY 1994 VL 99 IS D11 BP 23117 EP 23129 DI 10.1029/94JD01617 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PT032 UT WOS:A1994PT03200030 ER PT J AU GAWRONSKI, W BIENKIEWICZ, B HILL, RE AF GAWRONSKI, W BIENKIEWICZ, B HILL, RE TI WIND-INDUCED DYNAMICS OF A DEEP SPACE NETWORK ANTENNA SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID MODEL-REDUCTION AB Accurate spacecraft tracking by the NASA Deep Space Network (DSN) antennas must be assured during changing weather conditions. Wind disturbances are the main source of antenna vibrations, and consequently tracking errors. A wind force model is developed, and simulation results of wind-induced vibrations and pointing errors of the DSN antennas are presented. The antenna model includes the antenna structure, the elevation and azimuth servos, and the tracking controller. Simulation results show that pointing errors due to wind gusts are of the same order as errors due to wind steady state pressure, and that (similarly to steady state wind pressure) these errors satisfy the velocity quadratic law. The methodology presented is next used for wind disturbance estimation and for design of an antenna controller with wind disturbance rejection properties. C1 COLORADO STATE UNIV,DEPT CIVIL ENGN,FT COLLINS,CO 80523. HILL ENGN SERV,GLENDALE,CA 91214. RP GAWRONSKI, W (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 18 TC 5 Z9 6 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD NOV 17 PY 1994 VL 178 IS 1 BP 67 EP 77 DI 10.1006/jsvi.1994.1468 PG 11 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA PT428 UT WOS:A1994PT42800005 ER PT J AU LU, DQ CHEN, GH PERRY, JW GODDARD, WA AF LU, DQ CHEN, GH PERRY, JW GODDARD, WA TI VALENCE-BOND CHARGE-TRANSFER MODEL FOR NONLINEAR-OPTICAL PROPERTIES OF CHARGE-TRANSFER ORGANIC-MOLECULES SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID DONOR-ACCEPTOR POLYENES; ELECTRONIC HYPERPOLARIZABILITY; LENGTH ALTERNATION AB The nonlinear optical properties of charge-transfer organic materials are discussed in the framework of a simple valence-bond charge-transfer model. This model leads to analytic formulas for the absorption frequency, hyperpolarizabilities, and bond length alternation, all of which are described in terms of three parameters, V, t, and Q related to the band gap, bandwidth, and dipole moment of the charge-transfer state. These parameters are derivable from experiment or from theory. The valence-bond charge-transfer model provides a clear physical picture for the dependence of the hyperpolarizabilities on the structure of charge-transfer molecules and leads to good agreement with the trends predicted by the AM1 calculations. C1 CALTECH,CTR MAT & MOLEC SIMULAT,BECKMAN INST 13974,DIV CHEM & CHEM ENGN CN 8619,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91109. RI Chen, GuanHua/G-6630-2014 NR 22 TC 173 Z9 173 U1 1 U2 8 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD NOV 16 PY 1994 VL 116 IS 23 BP 10679 EP 10685 DI 10.1021/ja00102a037 PG 7 WC Chemistry, Multidisciplinary SC Chemistry GA PT130 UT WOS:A1994PT13000037 ER PT J AU MEYERS, F MARDER, SR PIERCE, BM BREDAS, JL AF MEYERS, F MARDER, SR PIERCE, BM BREDAS, JL TI ELECTRIC-FIELD MODULATED NONLINEAR-OPTICAL PROPERTIES OF DONOR-ACCEPTOR POLYENES - SUM-OVER-STATES INVESTIGATION OF THE RELATIONSHIP BETWEEN MOLECULAR POLARIZABILITIES (ALPHA, BETA, AND GAMMA) AND BOND-LENGTH ALTERNATION SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID CONJUGATED ORGANIC-MOLECULES; COUPLING-CONSTANTS; CHEMICAL-SHIFTS; CYANINE DYES; HYPERPOLARIZABILITIES; SUSCEPTIBILITY; SPECTROSCOPY; MEROCYANINE; DERIVATIVES; EXCITATIONS AB We investigate the influence of an external, static electric field upon the relationship between the structure, spatial distribution of electron density, and linear and nonlinear polarizabilities for a set of pi-electron chromophores. The bond length alternation (BLA) and the pi-electron bond order alternation (BOA) in the molecular structure are calculated as a function of the external electric field strength so that the dependence of the linear polarizability, alpha, second-order polarizability, beta, and third-order polarizability, gamma, can be expressed in terms of the BLA or BOA structural parameters. The calculated effect of the external electric field on the structure and electronic properties of the chromophores is similar to that resulting from donor-acceptor substituents on a segment of the chromophore or from changing the dielectric properties of the environment around the molecule, e.g., increasing the polarity of the solvent. The incorporation of a static electric field into the calculations provides a more realistic treatment of the nonlinear optical properties of the chromophore in the condensed phase and suggests strategies to optimize these properties by adjusting the dielectric properties of the medium around the chromophore. C1 CALTECH,BECKMAN INST,PASADENA,CA 91125. UNIV MONS HAINAUT,CTR RES MOLEC ELECTR & PHOTON,B-7000 MONS,BELGIUM. CALTECH,JET PROP LAB,PASADENA,CA 91109. HUGHES AIRCRAFT CO,RADAR SYST GRP,LOS ANGELES,CA 90009. RI Bredas, Jean-Luc/A-3431-2008 OI Bredas, Jean-Luc/0000-0001-7278-4471 NR 76 TC 606 Z9 614 U1 9 U2 65 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD NOV 16 PY 1994 VL 116 IS 23 BP 10703 EP 10714 DI 10.1021/ja00102a040 PG 12 WC Chemistry, Multidisciplinary SC Chemistry GA PT130 UT WOS:A1994PT13000040 ER PT J AU ALFREY, CP UDDEN, MM DRISCOLL, T HUNTOON, C AF ALFREY, CP UDDEN, MM DRISCOLL, T HUNTOON, C TI ABRUPT CESSATION IN RELEASE OF RED-BLOOD-CELLS INTO BLOOD DURING SPACEFLIGHT SO BLOOD LA English DT Meeting Abstract C1 BAYLOR COLL MED,HOUSTON,TX 77030. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU W B SAUNDERS CO PI PHILADELPHIA PA INDEPENDENCE SQUARE WEST CURTIS CENTER, STE 300, PHILADELPHIA, PA 19106-3399 SN 0006-4971 J9 BLOOD JI Blood PD NOV 15 PY 1994 VL 84 IS 10 SU 1 BP A119 EP A119 PG 1 WC Hematology SC Hematology GA PR754 UT WOS:A1994PR75400461 ER PT J AU HO, CW HORWITZ, JL MOORE, TE AF HO, CW HORWITZ, JL MOORE, TE TI DE1 OBSERVATIONS OF POLAR O+ STREAM BULK PARAMETERS AND COMPARISON WITH A MODEL OF THE CENTRIFUGALLY-ACCELERATED POLAR WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PLASMA; CAP; SIMULATION; OUTFLOW AB A survey of bulk parameters of analyzable O+ outward streams in the midaltitude (3-4.7 R(E) geocentric distance) polar cap magnetosphere is obtained from measurements by the Retarding Ion Mass Spectrometer (RIMS) aboard the Dynamics Explorer 1 (DE1) spacecraft. There is wide scatter in the obtained densities, but they do display discernible trends: the average O+ density in these streams decreases from about 30 ions cm-3 at 3.5 R(E) to about 1 ion cm-3 at 4.6 R(E). The streaming velocities are somewhat more defined, and their average increases from about 8 km s-1 at 3.5 R(E) to about 12 km s-1 at 4.6 R(E). The outward ion flux increases by a factor of 4 with magnetic activity from K(p) = 2 to 5. We have further compared these observational trends with model profiles for the centrifugally-accelerated polar wind as recently described by Horwitz et al. [1994]. The large outflow velocities observed can be understood in part as centrifugally-driven by convection with ionospheric electric field magnitudes of the order 50-70 mV m-1, perhaps including plasma expansion effects. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP HO, CW (reprint author), UNIV ALABAMA,CSPAR,HUNTSVILLE,AL 35899, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 13 TC 8 Z9 8 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 NOV 15 PY 1994 VL 21 IS 23 BP 2459 EP 2462 DI 10.1029/94GL02340 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400003 ER PT J AU LONG, SR HUANG, NE MOLLOCHRISTENSEN, E JACKSON, FC GEERNAERT, GL AF LONG, SR HUANG, NE MOLLOCHRISTENSEN, E JACKSON, FC GEERNAERT, GL TI DIRECTIONAL WIND-WAVE DEVELOPMENT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Using aircraft radar instruments designed for sea surface wave measurements, we have obtained fetch-limited directional wind wave spectra under steady off-shore wind conditions. The results from these observations in different areas at different times show that, up to a fetch of 150 km, the dominant waves propagate at an angle to the wind. The angle is near to that suggested by the Phillips resonance wind wave generation condition, but with one important difference: The waves are not always symmetric to the left and right of the wind. Most of the cases show the eventual dominance of one side lobe. The asymmetry of the wave direction relative to the wind suggests that the surface wind stress vector may not always be parallel to the mean wind direction. C1 NASA, GODDARD SPACE FLIGHT CTR, HYDROSPHER PROC LAB, OCEANS & ICE BRANCH, GREENBELT, MD 20771 USA. UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, LA JOLLA, CA 92093 USA. RP LONG, SR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, WALLOPS FLIGHT FACIL, HYDROSPHER PROC LAB, OBSERVAT SCI BRANCH, WALLOPS ISL, VA 23337 USA. RI Long, Steven/D-7248-2012 NR 19 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 1994 VL 21 IS 23 BP 2503 EP 2506 DI 10.1029/94GL01916 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400014 ER PT J AU COHEN, RC WENNBERG, PO STIMPFLE, RM KOPLOW, J ANDERSON, JG FAHEY, DW WOODBRIDGE, EL KEIM, ER GAO, R PROFFITT, MH LOEWENSTEIN, M CHAN, KR AF COHEN, RC WENNBERG, PO STIMPFLE, RM KOPLOW, J ANDERSON, JG FAHEY, DW WOODBRIDGE, EL KEIM, ER GAO, R PROFFITT, MH LOEWENSTEIN, M CHAN, KR TI ARE MODELS OF CATALYTIC REMOVAL OF O(3) BY HO(X) ACCURATE - CONSTRAINTS FROM IN-SITU MEASUREMENTS OF THE OH TO HO(2) RATIO SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SULFATE AEROSOLS; OZONE; STRATOSPHERE; HO2 AB Measurements of the ratio OH/HO2, NO, O3, ClO, and BrO were obtained at altitudes from 15-20 km and latitudes from 15-60-degrees-N. A method is presented for interpreting these simultaneous in situ observations that constraints the rates of chemical transformations that 1) are responsible for over half the ozone removal rate in the lower stratosphere via reactions of HO2 and 2) control the abundance of HO2 through coupling to nitrogen and halogen radicals. The results show our understanding of the chemical reactions controlling the partitioning of OH and HO2 is complete and accurate and that the potential effects of ''missing chemistry'' are strictly constrained in the region of the atmosphere encompassed by the observations. The analysis demonstrates that the sensitivity of the ratio OH/HO2 to changes in NO is described to within 12% by current models. This reduces by more than a factor of 2 the effect of uncertainty in the coupling of hydrogen and nitrogen radicals on the analysis of the potential effects of perturbations to odd nitrogen in the lower stratosphere. C1 HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. NOAA,AERON LAB,BOULDER,CO 80303. NOAA,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80303. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP COHEN, RC (reprint author), HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138, USA. RI Cohen, Ronald/A-8842-2011; Wennberg, Paul/A-5460-2012; Fahey, David/G-4499-2013 OI Cohen, Ronald/0000-0001-6617-7691; Fahey, David/0000-0003-1720-0634 NR 9 TC 31 Z9 31 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 NOV 15 PY 1994 VL 21 IS 23 BP 2539 EP 2542 DI 10.1029/94GL01713 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400023 ER PT J AU STIMPFLE, RM KOPLOW, JP COHEN, RC KOHN, DW WENNBERG, PO JUDAH, DM TOOHEY, DW AVALLONE, LM ANDERSON, JG SALAWITCH, RJ WOODBRIDGE, EL WEBSTER, CR MAY, RD PROFFITT, MH AIKEN, K MARGITAN, J LOEWENSTEIN, M PODOLSKE, JR PFISTER, L CHAN, KR AF STIMPFLE, RM KOPLOW, JP COHEN, RC KOHN, DW WENNBERG, PO JUDAH, DM TOOHEY, DW AVALLONE, LM ANDERSON, JG SALAWITCH, RJ WOODBRIDGE, EL WEBSTER, CR MAY, RD PROFFITT, MH AIKEN, K MARGITAN, J LOEWENSTEIN, M PODOLSKE, JR PFISTER, L CHAN, KR TI THE RESPONSE OF CLO RADICAL CONCENTRATIONS TO VARIATIONS IN NO2 RADICAL CONCENTRATIONS IN THE LOWER STRATOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INSITU MEASUREMENTS; REACTIVE NITROGEN; ER-2 AIRCRAFT; PINATUBO; LATITUDE; AEROSOLS AB The response of ClO concentrations to changes in NO2 concentrations has been inferred from simultaneous observations of [ClO], [NO], [NO2] and [O3] in the mid-latitude lower stratosphere. This analysis demonstrates that [ClO] is inversely correlated with [NO2], consistent with formation and photolysis of [ClONO2]. A factor of ten range in the concentration of NO2 was sampled (0.1 to 1 x 10(9) mol/cm3), with a comparable range in the ratio of [ClO] to total available inorganic chlorine (1% less-than-or-equal-to [ClO]/[Cl(y)] less-than-or-equal-to 5%.) This analysis leads to an estimate of [ClONO2]/[Cl(y)] = 0.12 (x/divided-by 2), in the mid-latitude, lower-stratospheric air masses sampled. C1 UNIV CALIF IRVINE,IRVINE,CA 92717. HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138. NOAA,AERON LAB,BOULDER,CO 80303. NOAA,COOPERAT INST ENVIRONM RES,BOULDER,CO 80303. JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP STIMPFLE, RM (reprint author), HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138, USA. RI Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Toohey, Darin/A-4267-2008; Wennberg, Paul/A-5460-2012 OI Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; Toohey, Darin/0000-0003-2853-1068; NR 22 TC 34 Z9 34 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 NOV 15 PY 1994 VL 21 IS 23 BP 2543 EP 2546 DI 10.1029/94GL02373 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400024 ER PT J AU SALAWITCH, RJ WOFSY, SC WENNBERG, PO COHEN, RC ANDERSON, JG FAHEY, DW GAO, RS KEIM, ER WOODBRIDGE, EL STIMPFLE, RM KOPLOW, JP KOHN, DW WEBSTER, CR MAY, RD PFISTER, L GOTTLIEB, EW MICHELSEN, HA YUE, GK WILSON, JC BROCK, CA JONSSON, HH DYE, JE BAUMGARDNER, D PROFFITT, MH LOEWENSTEIN, M PODOLSKE, JR ELKINS, JW DUTTON, GS HINTSA, EJ DESSLER, AE WEINSTOCK, EM KELLY, KK BOERING, KA DAUBE, BC CHAN, KR BOWEN, SW AF SALAWITCH, RJ WOFSY, SC WENNBERG, PO COHEN, RC ANDERSON, JG FAHEY, DW GAO, RS KEIM, ER WOODBRIDGE, EL STIMPFLE, RM KOPLOW, JP KOHN, DW WEBSTER, CR MAY, RD PFISTER, L GOTTLIEB, EW MICHELSEN, HA YUE, GK WILSON, JC BROCK, CA JONSSON, HH DYE, JE BAUMGARDNER, D PROFFITT, MH LOEWENSTEIN, M PODOLSKE, JR ELKINS, JW DUTTON, GS HINTSA, EJ DESSLER, AE WEINSTOCK, EM KELLY, KK BOERING, KA DAUBE, BC CHAN, KR BOWEN, SW TI THE DISTRIBUTION OF HYDROGEN, NITROGEN, AND CHLORINE RADICALS IN THE LOWER STRATOSPHERE - IMPLICATIONS FOR CHANGES IN O(3) DUE TO EMISSION OF NO(Y) FROM SUPERSONIC AIRCRAFT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SULFATE AEROSOLS; OZONE; CHEMISTRY AB In situ measurements of hydrogen, nitrogen, and chlorine radicals obtained in the lower stratosphere during SPADE are compared to results from a photochemical model that assimilates measurements of radical precursors and environmental conditions. Models allowing for heterogeneous hydrolysis of N2O5 agree well with measured concentrations of NO and ClO, but concentrations of HO2 and OH are underestimated by 10 to 25%, concentrations of NO2 are overestimated by 10 to 30%, and concentrations of HCl are overestimated by a factor of 2. Discrepancies for [OH] and [HO2] are reduced if we allow for higher yields of O(1D) from O3 photolysis and for heterogeneous production of HNO2. The data suggest more efficient catalytic removal of O3 by hydrogen and halogen radicals relative to nitrogen oxide radicals than predicted by models using recommended rates and cross sections. Increases in [O3] in the lower stratosphere may be larger in response to inputs of NO(y) from supersonic aircraft than estimated by current assessment models. C1 NOAA,AERON LAB,BOULDER,CO 80307. JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. UNIV DENVER,DENVER,CO 80210. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. NOAA,CLIMATE MONITORING & DIAGNOST LAB,ROCKVILLE,MD 20852. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP SALAWITCH, RJ (reprint author), HARVARD UNIV,CAMBRIDGE,MA 02138, USA. RI Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Brock, Charles/G-3406-2011; Wennberg, Paul/A-5460-2012; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013; Dessler, Andrew/G-8852-2012 OI Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; Brock, Charles/0000-0002-4033-4668; Fahey, David/0000-0003-1720-0634; Dessler, Andrew/0000-0003-3939-4820 NR 19 TC 63 Z9 63 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 1994 VL 21 IS 23 BP 2547 EP 2550 DI 10.1029/94GL02781 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400025 ER PT J AU SALAWITCH, RJ WOFSY, SC WENNBERG, PO COHEN, RC ANDERSON, JG FAHEY, DW GAO, RS KEIM, ER WOODBRIDGE, EL STIMPFLE, RM KOPLOW, JP KOHN, DW WEBSTER, CR MAY, RD PFISTER, L GOTTLIEB, EW MICHELSEN, HA YUE, GK PRATHER, MJ WILSON, JC BROCK, CA JONSSON, HH DYE, JE BAUMGARDNER, D PROFFITT, MH LOEWENSTEIN, M PODOLSKE, JR ELKINS, JW DUTTON, GS HINTSA, EJ DESSLER, AE WEINSTOCK, EM KELLY, KK BOERING, KA DAUBE, BC CHAN, KR BOWEN, SW AF SALAWITCH, RJ WOFSY, SC WENNBERG, PO COHEN, RC ANDERSON, JG FAHEY, DW GAO, RS KEIM, ER WOODBRIDGE, EL STIMPFLE, RM KOPLOW, JP KOHN, DW WEBSTER, CR MAY, RD PFISTER, L GOTTLIEB, EW MICHELSEN, HA YUE, GK PRATHER, MJ WILSON, JC BROCK, CA JONSSON, HH DYE, JE BAUMGARDNER, D PROFFITT, MH LOEWENSTEIN, M PODOLSKE, JR ELKINS, JW DUTTON, GS HINTSA, EJ DESSLER, AE WEINSTOCK, EM KELLY, KK BOERING, KA DAUBE, BC CHAN, KR BOWEN, SW TI THE DIURNAL-VARIATION OF HYDROGEN, NITROGEN, AND CHLORINE RADICALS - IMPLICATIONS FOR THE HETEROGENEOUS PRODUCTION OF HNO2 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ENVIRONMENTAL CHAMBERS; PEROXYNITRIC ACID; STRATOSPHERE AB In situ measurements of hydrogen, nitrogen, and chlorine radicals obtained through sunrise and sunset in the lower stratosphere during SPADE are compared to results from a photochemical model constrained by observed concentrations of radical precursors and environmental conditions. Models allowing for heterogeneous hydrolysis of N2O5 on sulfate aerosols agree with measured concentrations of NO, NO2, and ClO throughout the day, but fail to account for high concentrations of OH and HO2 observed near sunrise and sunset. The morning burst of [OH] and [HO2] coincides with the rise of [NO] from photolysis of NO2, suggesting a new source of HOx that photolyzes in the near UV (350 to 400 nm) spectral region. A model that allows for the heterogeneous production of HNO2 results in an excellent simulation of the diurnal variations of [OH] and [HO2]. C1 NOAA,AERON LAB,BOULDER,CO 80307. JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF IRVINE,IRVINE,CA 92717. UNIV DENVER,DENVER,CO 80210. RP SALAWITCH, RJ (reprint author), HARVARD UNIV,CAMBRIDGE,MA 02139, USA. RI Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Brock, Charles/G-3406-2011; Wennberg, Paul/A-5460-2012; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013; Dessler, Andrew/G-8852-2012 OI Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; Brock, Charles/0000-0002-4033-4668; Fahey, David/0000-0003-1720-0634; Dessler, Andrew/0000-0003-3939-4820 NR 13 TC 66 Z9 66 U1 3 U2 5 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 NOV 15 PY 1994 VL 21 IS 23 BP 2551 EP 2554 DI 10.1029/94GL02782 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400026 ER PT J AU JAEGLE, L WEBSTER, CR MAY, RD FAHEY, DW WOODBRIDGE, EL KEIM, ER GAO, RS PROFFITT, MH STIMPFLE, RM SALAWITCH, RJ WOFSY, SC PFISTER, L AF JAEGLE, L WEBSTER, CR MAY, RD FAHEY, DW WOODBRIDGE, EL KEIM, ER GAO, RS PROFFITT, MH STIMPFLE, RM SALAWITCH, RJ WOFSY, SC PFISTER, L TI IN-SITU MEASUREMENTS OF THE NO2/NO RATIO FOR TESTING ATMOSPHERIC PHOTOCHEMICAL MODELS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DIODE-LASER SPECTROMETER; STRATOSPHERIC NO; OZONE; O-3; SPACELAB-3; PROFILES; N2O5 AB Simultaneous in situ measurements of NO2, NO, O3, ClO, pressure and temperature have been made for the first time, presenting a unique opportunity to test our current understanding of the photochemistry of the lower stratosphere. Data were collected from several flights of the ER-2 aircraft at mid-latitudes in May 1993 during NASA's Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE). The daytime ratio of NO2/NO remains fairly constant at 19 km with a typical value of 0.68 and standard deviation of +/- 0.17. The ratio observations are compared with simple steady-state calculations based on laboratory-measured reaction rates and modeled NO2 photolysis rates. At each measurement point the daytime NO2/NO with its measurement uncertainty overlap the results of steady-state calculations and associated uncertainty. However, over all the ER-2 flights examined, the model systematically overestimates the ratio by 40% on average. Possible sources of error are examined in both model and measurements. It is shown that more accurate laboratory determinations of the NO + O3 reaction rate and of the NO2 cross-sections in the 200-220 K temperature range characteristic of the lower stratosphere would allow for a more robust test of our knowledge of NOx photochemistry by reducing significant sources of uncertainties in the interpretation of stratospheric measurements. The present measurements are compared with earlier observations of the ratio at higher altitudes. C1 NOAA,AERON LAB,ROCKVILLE,MD 20852. HARVARD UNIV,CAMBRIDGE,MA 02138. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP JAEGLE, L (reprint author), JET PROP LAB,4800 OAK GROVE DR,183-401,PASADENA,CA 91109, USA. RI Salawitch, Ross/B-4605-2009; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Fahey, David/0000-0003-1720-0634 NR 22 TC 22 Z9 24 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 NOV 15 PY 1994 VL 21 IS 23 BP 2555 EP 2558 DI 10.1029/94GL02717 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400027 ER PT J AU HINTSA, EJ WEINSTOCK, EM DESSLER, AE ANDERSON, JG LOEWENSTEIN, M PODOLSKE, JR AF HINTSA, EJ WEINSTOCK, EM DESSLER, AE ANDERSON, JG LOEWENSTEIN, M PODOLSKE, JR TI SPADE H2O MEASUREMENTS AND THE SEASONAL CYCLE OF STRATOSPHERIC WATER-VAPOR SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB We present measurements of lower stratospheric water vapor obtained during the SPADE mission with a new high precision, fast response, Lyman-alpha hygrometer. The H2O data show a distinct seasonal cycle. For air that recently entered the stratosphere, data collected during the fall show much more water vapor than data from the spring. Fast quasi-horizontal mixing causes compact relationships between water and N2O to be established on relatively short time scales. The measurements are consistent with horizontal mixing times of a few months or less. Vertical mixing appears to cause the seasonal variations in water vapor to propagate up to levels corresponding to air that has been in the stratosphere approximately one year. C1 NASA,MOFFETT FIELD,CA 94035. RP HINTSA, EJ (reprint author), HARVARD UNIV,ATMOSPHER RES PROJECT,12 OXFORD ST,CAMBRIDGE,MA 02138, USA. RI Dessler, Andrew/G-8852-2012 OI Dessler, Andrew/0000-0003-3939-4820 NR 13 TC 42 Z9 42 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 NOV 15 PY 1994 VL 21 IS 23 BP 2559 EP 2562 DI 10.1029/94GL01279 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400028 ER PT J AU DESSLER, AE WEINSTOCK, EM HINTSA, EJ ANDERSON, JG WEBSTER, CR MAY, RD ELKINS, JW DUTTON, GS AF DESSLER, AE WEINSTOCK, EM HINTSA, EJ ANDERSON, JG WEBSTER, CR MAY, RD ELKINS, JW DUTTON, GS TI AN EXAMINATION OF THE TOTAL HYDROGEN BUDGET OF THE LOWER STRATOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WATER-VAPOR; METHANE; CH4; CO AB We analyze the hydrogen budget of the lower stratosphere using simultaneous in situ measurements of northern hemispheric water vapor (H2O) and methane (CH4) obtained during the spring Stratospheric Photochemistry, Aerosols, and Dynamics Expedition (SPADE), as well as previously published in situ H-2 data. Based on this data, we conclude that approximately two H2O molecules are produced for each CH4 molecule destroyed. This implies that H-2 production from CH4 oxidation is balanced by H-2 oxidation. The uncertainty in this analysis is greatly reduced by the use of multiple data sets. Additionally, we infer that, on an annual and global average, H2O enters the stratosphere with a mixing ratio of 4.2+/-0.5 ppmv, and that the quasi-conserved quantity 2x[CH4] + [H2O] has a value of 7.6+/-0.6 ppmv in these northern hemisphere air parcels (where [zeta] denotes the mixing ratio of the constituent zeta). C1 HARVARD UNIV,ATMOSPHER RES PROJECT,CAMBRIDGE,MA 02138. JET PROP LAB,PASADENA,CA 91109. NOAA,CMDL,BOULDER,CO 80303. RI Dessler, Andrew/G-8852-2012 OI Dessler, Andrew/0000-0003-3939-4820 NR 20 TC 60 Z9 60 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 NOV 15 PY 1994 VL 21 IS 23 BP 2563 EP 2566 DI 10.1029/94GL02283 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400029 ER PT J AU BOERING, KA DAUBE, BC WOFSY, SC LOEWENSTEIN, M PODOLSKE, JR KEIM, ER AF BOERING, KA DAUBE, BC WOFSY, SC LOEWENSTEIN, M PODOLSKE, JR KEIM, ER TI TRACER-TRACER RELATIONSHIPS AND LOWER STRATOSPHERIC DYNAMICS - CO2 AND N2O CORRELATIONS DURING SPADE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CARBON-DIOXIDE; ARCTIC VORTEX; OZONE LOSS; CONSTITUENTS; SIMULATIONS; WINTER AB Simultaneous measurements of CO2 and N2O from the NASA ER-2 aircraft during SPADE deployments in November 1992, April/May 1993, and October 1993 provide new information on transport rates in the lower stratosphere. The tropospheric seasonal cycle in CO2, superimposed on the long-term trend, is observed to propagate into the stratosphere. The compact correlations observed between CO2 and N2O indicate that meridional transport is sufficiently rapid to create a uniform set of relationships over the northern hemisphere up to at least 21 km even though CO2 changes significantly on a time scale of 8 to 12 weeks. The observed seasonal dependence of the correlations indicates that vertical transport above 20 km is slower in northern summer than in winter and slow throughout the year between 19 km and the tropopause. The inferred amplitude of the seasonal CO2 oscillation in the stratosphere, viewed relative to N2O, places constraints on the mean latitude for air entering the stratosphere. C1 HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. RP BOERING, KA (reprint author), HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138, USA. NR 21 TC 81 Z9 81 U1 0 U2 5 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 NOV 15 PY 1994 VL 21 IS 23 BP 2567 EP 2570 DI 10.1029/94GL01985 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400030 ER PT J AU WOFSY, SC BOERING, KA DAUBE, BC MCELROY, MB LOEWENSTEIN, M PODOLSKE, JR ELKINS, JW DUTTON, GS FAHEY, DW AF WOFSY, SC BOERING, KA DAUBE, BC MCELROY, MB LOEWENSTEIN, M PODOLSKE, JR ELKINS, JW DUTTON, GS FAHEY, DW TI VERTICAL TRANSPORT RATES IN THE STRATOSPHERE IN 1993 FROM OBSERVATIONS OF CO2, N2O AND CH4 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CONSTITUENTS; SIMULATIONS AB Measurements of CO2, N2O and CH4 are analyzed to define hemispheric average vertical exchange rates in the lower stratosphere from November 1992 to October 1993. Effective vertical diffusion coefficients were small in summer, less-than-or-equal-to 1 m2s-1 at altitudes below 25 km; values were similar near the tropopause in winter, but increased markedly with altitude. The analysis suggests possibly longer residence times for exhaust from stratospheric aircraft, and more efficient transport from 20 km to the middle stratosphere, than predicted by many current models. Seasonally-resolved measurements of stratopheric CO2 and N2O provide significant new constraints on rates for global-scale vertical transport. C1 NOAA,BOULDER,CO 80302. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP WOFSY, SC (reprint author), HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138, USA. RI 欧阳, 冰洁/G-2925-2011; Fahey, David/G-4499-2013 OI Fahey, David/0000-0003-1720-0634 NR 20 TC 14 Z9 14 U1 1 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 NOV 15 PY 1994 VL 21 IS 23 BP 2571 EP 2574 DI 10.1029/94GL02079 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400031 ER PT J AU WEBSTER, CR MAY, RD JAEGLE, L HU, H SANDER, SP GUNSON, MR TOON, GC RUSSELL, JM STIMPFLE, RM KOPLOW, JP SALAWITCH, RJ MICHELSEN, HA AF WEBSTER, CR MAY, RD JAEGLE, L HU, H SANDER, SP GUNSON, MR TOON, GC RUSSELL, JM STIMPFLE, RM KOPLOW, JP SALAWITCH, RJ MICHELSEN, HA TI HYDROCHLORIC-ACID AND THE CHLORINE BUDGET OF THE LOWER STRATOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OZONE DEPLETION; ARCTIC WINTER; LATITUDE; CLO; HCL AB Concentrations of HC1 measured in the lower stratosphere in 1993 by the ALIAS instrument on the ER-2 aircraft reveal that only 40% of inorganic chlorine (Cl(y), inferred from in situ measurements of organic chlorinated source gases) is present as HCl, significantly lower than model predictions. Although the sum of measured HCl, CIO, and CIONO2, the latter inferred from measurements of CIO and NO2, equals Cl(y) to within the uncertainty of measurement, it is systematically less than Cl(y) by 30-50%. This discrepancy suggests that concentrations of CIONO2 may exceed those of HC1 near 20 km altitude, consistent with a slower photolysis rate for CIONO2 than calculated using recommended cross sections. Comparison of profiles of HC1 measured during 1992 and 1993 at mid-latitudes by balloon (BLISS and MARKIV), space shuttle (ATMOS), and satellite (HALOE) instruments with the aircraft data reveal an apparent pressure dependence to the HC1 to Cl(y) ratio, consistent with a factor of 3-10 reduction in the photolysis rate for CIONO2 at ER-2 altitudes. However, the diurnal variation of CIO is well-simulated by models using the recommended photolysis rate, and simultaneous measurements of ClONO2 and HCl at mid-latitudes by ATMOS and MARKIV report HC1/HCl + CIONO2) ratios greater-than-or-equal-to 50%. Preliminary measurements by ALIAS in the southern hemisphere report HCl/Cl(y) values of about 75%. It is unclear to what extent elevated aerosol surface area, uncertainties in the estimation of Cl(y) or in the photolysis rates, or missing reactive pathways contribute to our inability to balance the budget of inorganic chlorine using the aircraft measurements. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. HARVARD UNIV,CAMBRIDGE,MA 02138. RP WEBSTER, CR (reprint author), JET PROP LAB,4800 OAK GROVE DR,183-401,PASADENA,CA 91109, USA. RI Salawitch, Ross/B-4605-2009 OI Salawitch, Ross/0000-0001-8597-5832 NR 20 TC 37 Z9 39 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 NOV 15 PY 1994 VL 21 IS 23 BP 2575 EP 2578 DI 10.1029/94GL02806 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400032 ER PT J AU ZHENG, J WEINHEIMER, AJ RIDLEY, BA LIU, SC SACHSE, GW ANDERSON, BE COLLINS, JE AF ZHENG, J WEINHEIMER, AJ RIDLEY, BA LIU, SC SACHSE, GW ANDERSON, BE COLLINS, JE TI AN ANALYSIS OF AIRCRAFT EXHAUST PLUMES FROM ACCIDENTAL ENCOUNTERS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AASE-II; DC-8 AB An analysis of data obtained during the second Airbone Arctic Stratospheric Expedition (AASE-II) was made with emphasis on aircraft exhaust plumes accidentally encountered during the mission. Twenty spikes were found with peak NO(y) increments greater-than-or-equal-to ppbv. The examination of CO and CO2 indicates that there was only one NO(y) spike having clearly corresponding spikes of both CO and CO2, and another four with unambigous CO2 spikes. No significant increases were found for CH4 and N2O for these 5 spikes. The ratio of the excess CO2 and NO(y) compares well with the ratio of published subsonic aircraft emission indices. The study of the selected spikes from the DC-8 and another two spikes observed during other missions shows that the odd nitrogen other than NO(x) accounts for a very small percentage of the NO(y) increase associated with the observed spikes. C1 NOAA,AERON LAB,BOULDER,CO 80303. UNIV COLORADO,CRIES,BOULDER,CO 80309. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP ZHENG, J (reprint author), NATL CTR ATMOSPHER RES,POB 3000,BOULDER,CO 80307, USA. NR 11 TC 20 Z9 20 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 NOV 15 PY 1994 VL 21 IS 23 BP 2579 EP 2582 DI 10.1029/94GL01694 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400033 ER PT J AU WEINHEIMER, AJ WALEGA, JG RIDLEY, BA GARY, BL BLAKE, DR BLAKE, NJ ROWLAND, FS SACHSE, GW ANDERSON, BE COLLINS, JE AF WEINHEIMER, AJ WALEGA, JG RIDLEY, BA GARY, BL BLAKE, DR BLAKE, NJ ROWLAND, FS SACHSE, GW ANDERSON, BE COLLINS, JE TI MERIDIONAL DISTRIBUTIONS OF NO(X), NO(Y) AND OTHER SPECIES IN THE LOWER STRATOSPHERE AND UPPER TROPOSPHERE DURING AASE-II SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EXPEDITION; NOX AB The meridional distribution of NO(x) in the lower stratosphere and upper troposphere is inferred from 10 flights of the NASA DC-8 in the northern winter of 1992, along with like distributions of NO(y), NO(x)/NO(y), CO, and C2Cl4. In the lowest few km of the stratosphere there is little vertical gradient in NO(x) over the range of latitudes measured (40-degrees-90-degrees-N). There is a substantial latitudinal gradient, with 50 pptv above the pole and 120 pptv near 40-degrees-N. In the uppermost few km of the troposphere, background values range from 30 pptv over the pole to 90 pptv near 40-degrees-N. On two occasions higher values, up to 140 pptv in the mean, were seen 2-3 km below the tropopause in association with frontal systems. The meridional distributions of CO and C2Cl4 show the same feature, suggesting that the source of the elevated NO(x) is near the earth's surface. C1 JET PROP LAB,PASADENA,CA 91109. UNIV CALIF IRVINE,DEPT CHEM,IRVINE,CA 92717. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP WEINHEIMER, AJ (reprint author), NATL CTR ATMOSPHER RES,POB 3000,BOULDER,CO 80307, USA. NR 10 TC 55 Z9 55 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 1994 VL 21 IS 23 BP 2583 EP 2586 DI 10.1029/94GL01897 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400034 ER PT J AU TRAUB, WA JUCKS, KW JOHNSON, DG COFFEY, MT MANKIN, WG TOON, GC AF TRAUB, WA JUCKS, KW JOHNSON, DG COFFEY, MT MANKIN, WG TOON, GC TI COMPARISON OF COLUMN ABUNDANCES FROM 3 INFRARED SPECTROMETERS DURING AASE-II SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC CONSTITUENTS; AIRBORNE MEASUREMENTS; ANTARCTICA; SPECTROSCOPY; SPECTRA; WINTER AB Three Fourier transform infrared (FTIR) spectrometers were on board the NASA DC-8 during the second Airborne Arctic Stratospheric Expedition (AASE II) in 1992. Two FTIRs used solar absorption and one used thermal emission. We compare over 2000 measurements from these 3 FTIRs, on 12 DC-8 flights, for closely coincident air masses and times, both inside and outside the polar vortex. In the majority of cases the offset biases are quite small, in the range 1-4%, and comparable to the absolute precisions expected. In most cases the rms scatter is in the range 4-11%; this scatter is unlikely to be geophysical, but rather is probably instrumental or analytical in origin. C1 NATL CTR ATMOSPHER RES,BOULDER,CO 80307. JET PROP LAB,PASADENA,CA 91109. RP TRAUB, WA (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. RI Johnson, David/F-2376-2015 OI Johnson, David/0000-0003-4399-5653 NR 16 TC 5 Z9 5 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 NOV 15 PY 1994 VL 21 IS 23 BP 2591 EP 2594 DI 10.1029/94GL01173 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400036 ER PT J AU TOON, GC BLAVIER, JF SZETO, JT AF TOON, GC BLAVIER, JF SZETO, JT TI LATITUDE VARIATIONS OF STRATOSPHERIC TRACE GASES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB We present vertical column abundances of H2O, N2O, HNO3, NO2, O3, HF, HCl, and ClNO3 determined from solar absorption spectra measured by the JPL MkIV interferometer from the NASA DC-8 aircraft. These observations, taken in 1987 and 1992, covered latitudes ranging from 85-degrees-S to 85-degrees-N. Although most gases display latitude symmetry, large asymmetries in H2O, HNO3, and O3 are apparent, which can be ascribed to processes enhanced by the colder Antarctic winter temperatures. RP TOON, GC (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 11 Z9 11 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 NOV 15 PY 1994 VL 21 IS 23 BP 2599 EP 2602 DI 10.1029/94GL02078 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400038 ER PT J AU WAUGH, DW PLUMB, RA NEWMAN, PA SCHOEBERL, MR LAIT, LR LOEWENSTEIN, M PODOLSKE, JR ELKINS, JW CHAN, KR AF WAUGH, DW PLUMB, RA NEWMAN, PA SCHOEBERL, MR LAIT, LR LOEWENSTEIN, M PODOLSKE, JR ELKINS, JW CHAN, KR TI FINE-SCALE, POLEWARD TRANSPORT OF TROPICAL AIR DURING AASE-2 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE LATITUDES; AEROSOL; TRACER AB The poleward transport of tropical air in the lower stratosphere during the winter period of the second Airborne Arctic Stratospheric Expedition (December 1991 - March 1992) is examined using contour advection calculations. These calculations show that filaments of tropical air extend into mid-latitudes, and are wrapped around the equatorward edge of the polar jet. Simultaneously filaments are drawn from the polar vortex and are intermingled with the filaments of tropical air. The tropical filaments are consistent with measurements of chemical tracers taken aboard the ER-2 and DC-8 aircraft which show localized regions, in mid-latitudes, of air with the characteristics of tropical air. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. RP WAUGH, DW (reprint author), MIT,CTR METEOROL & PHYS OCEANOG,CAMBRIDGE,MA 02139, USA. RI Newman, Paul/D-6208-2012; Waugh, Darryn/K-3688-2016 OI Newman, Paul/0000-0003-1139-2508; Waugh, Darryn/0000-0001-7692-2798 NR 24 TC 16 Z9 16 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 1994 VL 21 IS 23 BP 2603 EP 2606 DI 10.1029/94GL01082 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400039 ER PT J AU YUE, GK VEIGA, RE POOLE, LR ZAWODNY, JM PROFFITT, MH AF YUE, GK VEIGA, RE POOLE, LR ZAWODNY, JM PROFFITT, MH TI ESTIMATED SAGE-II OZONE MIXING RATIOS IN EARLY 19930 AND COMPARISONS WITH STRATOSPHERIC PHOTOCHEMISTRY, AEROSOLS AND DYNAMICS EXPEDITION MEASUREMENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VALIDATION AB An empirical time-series model for estimating ozone mixing ratios based on Stratospheric Aerosol and Gas Experiment II monthly mean ozone data for the period October 1984 through June 1991 has been developed. The modeling results for ozone mixing ratios in the 10- to 30-km region in early months of 1993 are presented. In situ ozone profiles obtained by a dual-beam UV-absorption ozone photometer during the Stratospheric Photochemistry, Aerosols and Dynamics Expedition campaign, May 1-14, 1993, are compared with the model results. With the exception of two profiles at altitudes below 16 km, ozone mixing ratios derived by the model and measured by the ozone photometer are in relatively good agreement within their individual uncertainties. The identified discrepancies in the two profiles are discussed. C1 SCI APPLICAT INT CORP,HAMPTON,VA 23666. NOAA,ERL,AERON LAB,BOULDER,CO 80303. UNIV COLORADO,CIRES,BOULDER,CO 80303. RP YUE, GK (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. NR 15 TC 2 Z9 2 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 NOV 15 PY 1994 VL 21 IS 23 BP 2607 EP 2610 DI 10.1029/94GL02282 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PT474 UT WOS:A1994PT47400040 ER PT J AU HINNANT, HE AF HINNANT, HE TI A FAST METHOD OF NUMERICAL QUADRATURE FOR P-VERSION FINITE-ELEMENT MATRICES SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article ID COMPLETE POLYNOMIALS; RULES AB A new technique of numerical quadrature especially suited for quadrilateral and hexahedron p-version finite element matrices is presented. This new technique separates the integrand into two parts, and numerically operates on each part separately. The objective of this scheme is to minimize the computational cost of integrating the entire element matrix as opposed to minimizing the cost of integrating a single function, The efficiency of the new technique is compared with Gaussian quadrature and found to take a small fraction of the computational effort. RP HINNANT, HE (reprint author), NASA,LANGLEY RES CTR,USA,VEHICLE STRUCT DIRECTORATE,MS 240,HAMPTON,VA 23681, USA. NR 12 TC 17 Z9 18 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD NOV 15 PY 1994 VL 37 IS 21 BP 3723 EP 3750 DI 10.1002/nme.1620372109 PG 28 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA PQ110 UT WOS:A1994PQ11000008 ER PT J AU SARUSI, G GUNAPALA, SD PARK, JS LEVINE, BF AF SARUSI, G GUNAPALA, SD PARK, JS LEVINE, BF TI DESIGN AND PERFORMANCE OF VERY LONG-WAVELENGTH GAAS ALXGA1-XAS QUANTUM-WELL INFRARED PHOTODETECTORS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID DETECTORS C1 CALTECH,CTR SPACE MICROELECTR TECHNOL,JET PROPULS LAB,PASADENA,CA 91109. RP SARUSI, G (reprint author), AT&T BELL LABS,MURRAY HILL,NJ 07974, USA. NR 13 TC 31 Z9 32 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 NOV 15 PY 1994 VL 76 IS 10 BP 6001 EP 6008 DI 10.1063/1.358351 PN 1 PG 8 WC Physics, Applied SC Physics GA PT846 UT WOS:A1994PT84600060 ER PT J AU ORIENT, OJ CHUTJIAN, A MURAD, E AF ORIENT, OJ CHUTJIAN, A MURAD, E TI OBSERVATION OF CH A-]X, CN B-]X, AND NH A-]X EMISSIONS IN GAS-PHASE COLLISIONS OF FAST O(P-3) ATOMS WITH HYDRAZINES SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID OSCILLATOR-STRENGTHS; SPECTRA; O(3P) C1 PHILLIPS LAB WSCI,BEDFORD,MA 01731. RP ORIENT, OJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 11 Z9 11 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 NOV 15 PY 1994 VL 101 IS 10 BP 8297 EP 8301 DI 10.1063/1.468095 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PR236 UT WOS:A1994PR23600003 ER PT J AU CARSEY, FD MCNUTT, L ROTHROCK, DA AF CARSEY, FD MCNUTT, L ROTHROCK, DA TI THE ALASKA SYNTHETIC-APERTURE-RADAR-FACILITY - INTRODUCTION SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Editorial Material C1 UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK. UNIV WASHINGTON,APPL PHYS LAB,SEATTLE,WA. RP CARSEY, FD (reprint author), CALTECH,JET PROP LAB,PASADENA,CA, USA. NR 4 TC 0 Z9 0 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 NOV 15 PY 1994 VL 99 IS C11 BP 22389 EP 22389 DI 10.1029/94JC02299 PG 1 WC Oceanography SC Oceanography GA PR668 UT WOS:A1994PR66800001 ER PT J AU LIU, AK PENG, CY WEINGARTNER, TJ AF LIU, AK PENG, CY WEINGARTNER, TJ TI OCEAN ICE INTERACTION IN THE MARGINAL ICE-ZONE USING SYNTHETIC-APERTURE RADAR IMAGERY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID EDGE-DETECTION; WAVES AB Ocean-ice interaction processes in the marginal ice zone (MIZ) by wind, waves, and mesoscale features, such as up/downwelling and eddies are studied using ERS 1 synthetic aperture radar (SAR) images and an ocean-ice interaction model. A sequence of seven SAR images of the MIZ in the Chukchi Sea with 3 or 6 days interval are investigated for ice edge advance/retreat. Simultaneous current measurements from the northeast Chukchi Sea, as well as the Barrow wind record, are used to, interpret the MIZ dynamics. SAR spectra of waves in ice and ocean waves in the Bering and Chukchi Sea are compared for the study of Wave propagation and dominant SAR imaging mechanism. By using the SAR-observed ice edge configuration and wind and wave field in the Chukchi Sea as inputs, a numerical simulation has been performed with the ocean-ice interaction model. After 3 days of wind and wave forcing the resulting ice edge configuration, eddy formation, and flow velocity field are shown to be consistent with SAR observations. C1 SCI SYST & APPL INC,LANHAM,MD 20706. UNIV ALASKA,INST MARINE SCI,FAIRBANKS,AK 99775. RP LIU, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,CODE 971,GREENBELT,MD 20771, USA. NR 24 TC 16 Z9 16 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 NOV 15 PY 1994 VL 99 IS C11 BP 22391 EP 22400 DI 10.1029/94JC01390 PG 10 WC Oceanography SC Oceanography GA PR668 UT WOS:A1994PR66800002 ER PT J AU FETTERER, FM GINERIS, D KWOK, R AF FETTERER, FM GINERIS, D KWOK, R TI SEA-ICE TYPE MAPS FROM ALASKA SYNTHETIC-APERTURE RADAR FACILITY IMAGERY - AN ASSESSMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article AB Synthetic aperture radar (SAR) imagery received at the Alaska SAR Facility is routinely and automatically classified on the Geophysical Processor System (GPS) to create ice type maps. We evaluated the wintertime performance of the GPS classification algorithm by comparing ice type percentages from supervised classification with percentages from the algorithm. The RMS difference for multiyear ice is about 6%, while the inconsistency in supervised classification is about 3%. The algorithm separates first-year from multiyear ice well, although it sometimes fails to correctly classify new ice and open water owing to the wide distribution of backscatter for these classes. Our results imply a high degree of accuracy and consistency in the growing archive of multiyear and first-year ice distribution maps. These results have implications for heat and mass balance studies which are furthered by the ability to accurately characterize ice type distributions over a large part of the Arctic. C1 SVERDRUP TECHNOL,BAY ST LOUIS,MS 39529. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP FETTERER, FM (reprint author), USN,RES LAB,REMOTE SENSING APPLICAT BRANCH,BAY ST LOUIS,MS 39529, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 21 TC 29 Z9 29 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-OCEANS JI J. Geophys. Res.-Oceans PD NOV 15 PY 1994 VL 99 IS C11 BP 22443 EP 22458 DI 10.1029/94JC01911 PG 16 WC Oceanography SC Oceanography GA PR668 UT WOS:A1994PR66800006 ER PT J AU HALL, DK FAGRE, DB KLASNER, F LINEBAUGH, G LISTON, GE AF HALL, DK FAGRE, DB KLASNER, F LINEBAUGH, G LISTON, GE TI ANALYSIS OF ERS-1 SYNTHETIC-APERTURE-RADAR DATA OF FROZEN LAKES IN NORTHERN MONTANA AND IMPLICATIONS FOR CLIMATE STUDIES SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ICE; TEMPERATURE AB Lakes that freeze each winter are good indicators of regional climate change if key parameters, such as freeze-up and breakup date and maximum ice thickness, are measured over a decade-scale time frame. Synthetic aperture radar (SAR) satellite data have proven to be especially useful for measurement of climatologically significant parameters characteristic of frozen lakes. In this paper, five lakes in Glacier National Park, Montana, have been studied both in the field and using ERS 1 SAR data during the 1992-1993 winter. The lakes are characterized by clear ice, sometimes with tubular or rounded bubbles, and often with a layer of snow ice on top of the clear ice. They are also often snow covered. Freeze-up is detected quite easily using ERS 1 SAR data as soon as a thin layer of ice forms. The effect of snow ice on the backscatter is thought to be significant but is, as yet, undetermined. On the five lakes studied, relative backscatter was found to increase with ice thickness until a maximum was reached in February. Breakup, an often ill-defined occurrence, is difficult to detect because surface water causes the SAR signal to be absorbed, thus masking the ice below. Comparison of the bubble structure of thaw lakes in northern Alaska with lakes in northern Montana has shown that the ice structure is quite different, and this difference may contribute to differential SAR signature evolution in the lakes of the two areas. C1 NATL BIOL SURVEY,W GLACIER,MT 59936. HUGHES STX CORP,LANHAM,MD 20706. UNIV SPACE RES ASSOC,SEABROOK,MD 20706. RP HALL, DK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 974,GREENBELT,MD 20771, USA. RI Hall, Dorothy/D-5562-2012 NR 27 TC 28 Z9 28 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-OCEANS JI J. Geophys. Res.-Oceans PD NOV 15 PY 1994 VL 99 IS C11 BP 22473 EP 22482 DI 10.1029/94JC01391 PG 10 WC Oceanography SC Oceanography GA PR668 UT WOS:A1994PR66800008 ER PT J AU ZABINSKI, JS DAY, AE DONLEY, MS DELLACORTE, C MCDEVITT, NT AF ZABINSKI, JS DAY, AE DONLEY, MS DELLACORTE, C MCDEVITT, NT TI SYNTHESIS AND CHARACTERIZATION OF A HIGH-TEMPERATURE OXIDE LUBRICANT SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID PULSED-LASER DEPOSITION; MOS2 THIN-FILMS; EVAPORATION AB PbMoO4 is a potential solid lubricant for use at elevated temperatures in oxidizing environments. Pulsed laser deposition (PLD) was utilized to grow thin films of this material because it allows good control over film chemistry and crystallinity. Films were grown at different substrate temperatures in vacuum and in partial pressures of oxygen. The chemistry and crystallinity of the films were evaluated using X-ray photoelectron spectroscopy, Raman spectroscopy, and glancing angle X-ray diffraction. Friction coefficients and wear lives were measured using a ball-on-flat tribometer at room temperature and 700 degrees C. Films deposited in vacuum, at room temperature and at 300 degrees C, were oxygen deficient. To adjust chemistry and crystallinity, films were grown in a partial pressure of oxygen (i.e. 6.7 x 10(-1) Pa). Stoichiometric, crystalline films of PbMoO4 were produced when films were grown at 300 degrees C in this environment. PbMoO4 films were lubricious (mu = 0.35) and long lived at 700 degrees C, but at room temperature had high friction and failed quickly. The properties of the films grown at the different conditions are discussed. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RAMSPEC RES,DAYTON,OH 45431. RP ZABINSKI, JS (reprint author), WRIGHT LAB,MLBT,MAT DIRECTORATE,WRIGHT PATTERSON AFB,OH 45433, USA. NR 16 TC 22 Z9 23 U1 3 U2 13 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD NOV 15 PY 1994 VL 29 IS 22 BP 5875 EP 5879 DI 10.1007/BF00366870 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA PU793 UT WOS:A1994PU79300018 ER PT J AU HIGGINS, RW SCHUBERT, SD AF HIGGINS, RW SCHUBERT, SD TI SIMULATED LIFE-CYCLES OF PERSISTENT ANTICYCLONIC ANOMALIES OVER THE NORTH PACIFIC - ROLE OF SYNOPTIC-SCALE EDDIES SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID HEMISPHERE WINTERTIME CIRCULATION; TRANSIENT EDDIES; BLOCKING EPISODE; EXPLOSIVE CYCLOGENESIS; ATMOSPHERIC BLOCKING; MEAN-FLOW; EDDY; PROPAGATION; INSTABILITY; VORTICITY AB This study examines the role of synoptic-scale eddies during the development of persistent anticyclonic height anomalies over the central North Pacific in a general circulation model under perpetual January conditions. The GCM replicates the basic characteristics of the evolution of the anomaly patterns found in observations. The life cycle is characterized by the rapid establishment of the major anomaly center and considerably longer maintenance and decay phases, which include the development of downstream anomaly centers. The simulation also shows a realistic evolution of synoptic-scale activity beginning with enhanced activity off the east coast of Asia prior to onset, followed by a northward shift of the Pacific storm track, which lasts throughout the-maintenance phase. The initial enhancement of synoptic-scale eddy activity is associated with a large-scale cyclonic anomaly that develops over Siberia several days prior to the onset of the main anticyclonic anomaly over the central North Pacific. The observations, however, show considerable interdecadel variability in the details of the composite onset behavior; it is unclear whether this variability is real or whether it reflects differences in the data assimilation systems. The role of the time mean flow and synoptic-scale eddies in the development of the persistent Pacific anomalies is studied within the context of a kinetic energy budget in which the flow is decomposed into the time mean, low-frequency (timescales longer than 10 days), and synoptic (timescales less than 6 days) components. The budget, which is carried out for the simulation at 500 mb, shows that the initial growth of the persistent anticyclonic anomalies is associated with barotropic conversions of energy, with approximately equal contributions coming from the mean flow and the synoptic-scale eddies. After onset the barotropic conversion from the mean flow dominates, whereas the decay phase is associated with baroclinic processes within the low-frequency flow. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. NR 55 TC 27 Z9 28 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 EI 1520-0469 J9 J ATMOS SCI JI J. Atmos. Sci. PD NOV 15 PY 1994 VL 51 IS 22 BP 3238 EP 3260 DI 10.1175/1520-0469(1994)051<3238:SLCOPA>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PT243 UT WOS:A1994PT24300003 ER PT J AU BAER, DS HANSON, RK NEWFIELD, ME GOPAUL, NKJM AF BAER, DS HANSON, RK NEWFIELD, ME GOPAUL, NKJM TI MULTIPLEXED DIODE-LASER SENSOR SYSTEM FOR SIMULTANEOUS H2O, O-2, AND TEMPERATURE-MEASUREMENTS SO OPTICS LETTERS LA English DT Article ID MODULATION SPECTROSCOPY; FLOWS AB A multiplexed diode-laser sensor system has been developed to monitor multiple species and measure multiple flowfield parameters along a single path with optical fibers and scanned-laser absorption techniques. Two InGaAsP lasers were tuned over H2O transitions near 1347 and 1392 nm, and an AlGaAs laser was tuned over an O-2 transition near 760.65 nm to record fully resolved absorption concurrently at a repetition rate of 2 kHz. The system was applied to measure H2O, O-2, and temperature simultaneously in a heated static cell and in room air. Wavelength modulation with second-harmonic detection, applied simultaneously in the O-2 measurements, yielded a minimum detectable absorbance of 1.6 x 10(-6)/Hz(1/2) and an O-2 detectivity of 6.3 parts in 10(6) in a 1-m path length. C1 NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035. RP BAER, DS (reprint author), STANFORD UNIV,HIGH TEMP GASDYNAM LAB,STANFORD,CA 94305, USA. NR 11 TC 84 Z9 88 U1 0 U2 8 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD NOV 15 PY 1994 VL 19 IS 22 BP 1900 EP 1902 DI 10.1364/OL.19.001900 PG 3 WC Optics SC Optics GA PR094 UT WOS:A1994PR09400034 PM 19855691 ER PT J AU MUTO, T TATSUMI, T IWAMOTO, N AF MUTO, T TATSUMI, T IWAMOTO, N TI AXION EMISSION FROM MESON CONDENSATES SO PHYSICAL REVIEW D LA English DT Article ID DIRECT URCA PROCESS; NEUTRON-STARS; X-RAY; PION-CONDENSATION; KAON CONDENSATION; CHIRAL SYMMETRY; STRANGE GOINGS; BETA-DECAY; MATTER; PULSAR C1 UNIV HEIDELBERG,INST THEORET PHYS,D-69120 HEIDELBERG,GERMANY. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB ES65,HUNTSVILLE,AL 35812. KYOTO UNIV,YUKAWA INST THEORET PHYS,KYOTO 60601,JAPAN. RP MUTO, T (reprint author), KYOTO UNIV,DEPT PHYS,KYOTO 60601,JAPAN. NR 54 TC 3 Z9 3 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 NOV 15 PY 1994 VL 50 IS 10 BP 6089 EP 6099 DI 10.1103/PhysRevD.50.6089 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PU841 UT WOS:A1994PU84100011 ER PT J AU GYUK, G TURNER, MS AF GYUK, G TURNER, MS TI RELAXING THE BIG-BANG BOUND TO THE BARYON DENSITY SO PHYSICAL REVIEW D LA English DT Article ID COLD DARK-MATTER; MINIMAL ISOCURVATURE MODEL; PECULIAR VELOCITY-FIELD; TAU-NEUTRINO MASS; PRIMORDIAL NUCLEOSYNTHESIS; IRAS-GALAXIES; UNIVERSE; COSMOLOGY C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP GYUK, G (reprint author), UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637, USA. NR 37 TC 15 Z9 15 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD NOV 15 PY 1994 VL 50 IS 10 BP 6130 EP 6134 DI 10.1103/PhysRevD.50.6130 PG 5 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PU841 UT WOS:A1994PU84100016 ER PT J AU WANG, Y AF WANG, Y TI POLYNOMIAL HYBRID INFLATION SO PHYSICAL REVIEW D LA English DT Article ID LARGE-SCALE STRUCTURE; HOT DARK-MATTER; PERTURBATIONS; UNIVERSE; COSMOLOGY; SPECTRA RP WANG, Y (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. RI Wang, Yun/B-5724-2011 OI Wang, Yun/0000-0002-4749-2984 NR 21 TC 14 Z9 14 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 NOV 15 PY 1994 VL 50 IS 10 BP 6135 EP 6143 DI 10.1103/PhysRevD.50.6135 PG 9 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PU841 UT WOS:A1994PU84100017 ER PT J AU BAUSCHLICHER, CW AF BAUSCHLICHER, CW TI AN AB-INITIO STUDY OF HCUCO SO CHEMICAL PHYSICS LETTERS LA English DT Article ID COUPLED-CLUSTER THEORY; ELECTRON CORRELATION; BINDING-ENERGIES; BASIS-SETS; ATOMS; CUCO; NICO AB HCuCO is studied using a large Gaussian basis set at the coupled cluster singles and doubles level of theory, including a perturbational estimate of the connected triples (CCSD(T)). In contrast with CuCO, HCuCO is linear. The Cu-CO bond in HCuCO is significantly stronger than in CuCO. These differences between HCuCO and CuCO are discussed in terms of the Cu-H bond polarizing the Cu 4s electron away from the CO. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 21 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD NOV 11 PY 1994 VL 229 IS 6 BP 577 EP 580 DI 10.1016/0009-2614(94)01088-9 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PQ551 UT WOS:A1994PQ55100001 ER PT J AU COLOMBI, S AF COLOMBI, S TI A SKEWED LOGNORMAL APPROXIMATION TO THE PROBABILITY-DISTRIBUTION FUNCTION OF THE LARGE-SCALE DENSITY FIELD SO ASTROPHYSICAL JOURNAL LA English DT Article DE LARGE-SCALE STRUCTURE OF UNIVERSE; GALAXIES, CLUSTERING ID UNIVERSE; GRAVITY; COUNTS; FLUCTUATIONS; CELLS AB I propose a method to fit the probability distribution function (PDF) of the large-scale density field rho, motivated by a Lagrangian version of the continuity equation. It consists in applying the Edgeworth expansion to the quantity Phi = log rho - [log rho]. The method is tested on the matter particle distribution in two cold dark matter N-body simulations of different physical sizes to cover a large dynamic range. It is seen to be very efficient, even in the nonlinear regime, and may thus be used as an analytical tool to study the effect on the PDF of the transition between the weakly nonlinear regime and the highly nonlinear regime. RP COLOMBI, S (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,POB 500,BATAVIA,IL 60510, USA. NR 18 TC 40 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 NOV 10 PY 1994 VL 435 IS 2 BP 536 EP 539 DI 10.1086/174834 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ970 UT WOS:A1994PQ97000003 ER PT J AU NEMIROFF, RJ AF NEMIROFF, RJ TI MAGNIFICATION BIAS IN GALACTIC MICROLENSING SEARCHES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, HALO; GRAVITATIONAL LENSING; STARS, LOW-MASS, BROWN DWARFS ID GRAVITATIONAL LENSING EXPERIMENT; HALO; OBJECTS; BULGE AB It is shown that a significant amount of detectable gravitational microlensing events that could potentially be found by Massively Parallel Photometry (MAPP) projects (such as the MACHO, EROS, and OGLE collaborations) will occur for stars too dim to be easily noticed individually by these projects. This is the result of a large magnification bias effect, a bias of including high-magnification events in any flux-limited sample. The probability of detecting these events may be as high as 2.3 times the lensing probability of stars currently being monitored by MAPP collaborations. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP NEMIROFF, RJ (reprint author), GEORGE MASON UNIV,CSI,CODE 6681,GREENBELT,MD 20771, USA. NR 19 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 1994 VL 435 IS 2 BP 682 EP 684 DI 10.1086/174845 PN 1 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ970 UT WOS:A1994PQ97000014 ER PT J AU DISSLY, RW ALLEN, M ANICICH, VG AF DISSLY, RW ALLEN, M ANICICH, VG TI H-2-RICH INTERSTELLAR GRAIN MANTLES - AN EQUILIBRIUM DESCRIPTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, GRAINS; INTERSTELLAR, MOLECULES; MOLECULAR PROCESSES ID AMORPHOUS ICE; WATER ICE; ADSORPTION; FEATURES; CLOUD; H-2 AB Experiments simulating the codeposition of molecular hydrogen and water ice on interstellar grains demonstrate that amorphous water ice at 12 K can incorporate a substantial amount of H-2, up to a mole ratio of H-2/H2O = 0.53. We find that the physical behavior of similar to 80% of the hydrogen can be explained satisfactorily in terms of an equilibrium population, thermodynamically governed by a wide distribution of binding site energies. Such a description predicts that gas phase accretion could lead to mole fractions of H-2 in interstellar grain mantles of nearly 0.3; for the probable conditions of WL5 in the rho Ophiuchi cloud, an H-2 mole fraction of between 0.05 and 0.3 is predicted, in possible agreement with the observed abundance reported by Sandford, Allamandola, & Geballe. Accretion of gas phase H-2 onto grain mantles, rather than photochemical production of H-2 within the ice, could be a general explanation for frozen H-2 in interstellar ices. We speculate on the implications of such a composition for grain mantle chemistry and physics. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. RP DISSLY, RW (reprint author), CALTECH,DIV GEOL & PLANETARY SCI,MS170-25,PASADENA,CA 91125, USA. NR 26 TC 20 Z9 20 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 NOV 10 PY 1994 VL 435 IS 2 BP 685 EP 692 DI 10.1086/174846 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ970 UT WOS:A1994PQ97000015 ER PT J AU BORKOWSKI, KJ HARRINGTON, JP BLAIR, WP BREGMAN, JD AF BORKOWSKI, KJ HARRINGTON, JP BLAIR, WP BREGMAN, JD TI THE DUST IN THE HYDROGEN-POOR EJECTA OF ABELL-30 SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; ISM, ABUNDANCES; PLANETARY NEBULAE, INDIVIDUAL (ABELL 30); STARS, MASS-LOSS ID POLYCYCLIC AROMATIC-HYDROCARBONS; PLANETARY-NEBULAE; INFRARED-EMISSION; TEMPERATURE-FLUCTUATIONS; INTERSTELLAR GRAINS; AMORPHOUS-CARBON; ACTIVE GALAXIES; IRAS; SPECTRA; MODEL AB We present new optical and near-infrared images of the hydrogen-poor planetary nebula Abell 30 and produce detailed models that account for the major observed morphological and IR properties. By imaging the nebula in the K band, we confirm the presence of hot dust in an expanding equatorial ring of H-poor gas. No emission was detected from the H-poor polar knots, suggesting a dust deficiency there relative to the equatorial ring. The near-IR emission is attributed to small carbonaceous dust grains which are stochastically heated by stellar ultraviolet photons. Using an adaptive version of a matrix method devised by Guhathakurta & Draine (1989) to model stochastic heating, we find that the near-IR spectrum observed by Dinerstein and Lester (1984) requires the presence of dust grains down to similar to 0.0007 mu m in radius. This minimum grain radius is in excellent agreement with our calculations of the grain destruction by energetic stellar UV photons: we find that carbon clusters with less than similar to 140 atoms (0.00072 mu m in radius) are destroyed by stellar UV photons in similar to 1000 yr, the kinematic age of H-poor ejecta. Modeling of the far-IR dust emission implies that the bulk of the dust mass in A30 must reside at distances several times greater than the distance of the equatorial ring from the central star. This spatial dust distribution is attributed to the interaction of the stellar wind with the inhomogeneous H-poor ejecta. Most of the H-poor gas and dust has been apparently carried outward by the stellar wind, leaving behind dense, H-poor knots with prominent wind-blown tails in the equatorial ring and in the polar knots. This picture is supported by the presence of a stellar wind-blown bubble within the H-rich envelope in our optical images. C1 JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BORKOWSKI, KJ (reprint author), UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742, USA. NR 56 TC 35 Z9 35 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 NOV 10 PY 1994 VL 435 IS 2 BP 722 EP 733 DI 10.1086/174849 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ970 UT WOS:A1994PQ97000018 ER PT J AU STEIMANCAMERON, TY YOUNG, K SCARGLE, JD CRUTCHFIELD, JP IMAMURA, JN WOLFF, MT WOOD, KS AF STEIMANCAMERON, TY YOUNG, K SCARGLE, JD CRUTCHFIELD, JP IMAMURA, JN WOLFF, MT WOOD, KS TI DRIPPING HANDRAILS AND THE QUASI-PERIODIC OSCILLATIONS OF THE AM-HERCULIS OBJECTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, CLOSE; HYDRODYNAMICS; NOVAE, CATACLYSMIC VARIABLES; STARS, OSCILLATIONS ID DRIVEN RADIATIVE SHOCKS; NOISE; DWARFS AB AM Her objects exhibit periodic, quasi-periodic, and aperiodic variability on timescales ranging from seconds to years. Here, we investigate a process for the production of aperiodic and quasi-periodic accretion rate fluctuations. We consider the nonlinear dynamical model known as the dripping handrail (DHR). The DHR, basically a model for certain types of spatially extended systems and loosely based on water condensing on and dripping off a handrail, has recently been used as a model for the quasi-periodic oscillations and very low frequency noise of the low-mass X-ray binary Sco X-1. Here, we show that (1) the DHR is a robust QPO generation process in that it leads to QPO production under a wide range of conditions and assumptions; (2) the phenomenology of the DHR is consistent with the observed aperiodic and quasi-periodic variability of the AM Her QPO source VV Pup over timescales ranging from 16 ms to 20 a; and (3) a single DHR model can produce both broadband QPOs and features with quality Q > 20 as observed in several AM Her QPO sources. C1 UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. UNIV OREGON,INST THEORET SCI,EUGENE,OR 97403. UNIV OREGON,DEPT PHYS,EUGENE,OR 97403. USN,RES LAB,WASHINGTON,DC 20375. RP STEIMANCAMERON, TY (reprint author), NASA,AMES RES CTR,CTR THEORET STUDIES,MOFFETT FIELD,CA 94035, USA. NR 14 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 NOV 10 PY 1994 VL 435 IS 2 BP 775 EP 783 DI 10.1086/174855 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ970 UT WOS:A1994PQ97000024 ER PT J AU LIN, DNC HAYASHI, M BELL, KR OHASHI, N AF LIN, DNC HAYASHI, M BELL, KR OHASHI, N TI IS HL TAURI AN FU ORIONIS SYSTEM IN QUIESCENCE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; STARS, INDIVIDUAL (HL TAURI); STARS, FORMATION ID YOUNG STELLAR OBJECTS; ACCRETION DISKS; CIRCUMSTELLAR GAS; PROTOSTELLAR DISKS; MOLECULAR CLOUD; STAR FORMATION; R-MONOCEROTIS; INSTABILITIES; EVOLUTION; COLLAPSE AB A recent Nobeyama map of HL Tau reveals that gas is infalling in a flattened region similar to 1400 AU around the central star. The apparent motion of the gas provides the necessary condition for the formation of a Keplerian disk with a radius comparable to the size of the primordial solar nebula. The inferred mass infall rate onto the disk is similar or equal to 5 x 10(-6) M. yr(-1), which greatly exceeds the maximum estimate of the accretion rate onto the central star (similar to 7 x 10(-7) M. yr(-1)). Consequently, mass must currently be accumulating in the disk. The estimated age and disk mass of HL Tau suggest that the accumulated matter has been flushed repeatedly on a timescale < 10(4) yr. Based on the similarities between their evolution patterns, we propose that HL Tau is an FU Orionis system in quiescence. In addition to HL Tau, 14 out of 86 pre-main-sequence stars in the Taurus-Auriga dark clouds have infrared luminosities much greater than their otherwise normal extinction-corrected stellar luminosities. These sources also tend to have flat spectra which may be due to the reprocessing of radiation by dusty, flattened, collapsing envelopes with infall rates a few 10(-6) M. yr(-1). Such rates are much larger than estimated central object accretion rates for these systems, which suggests that mass must also be accumulating in these disks. If these sources are FU Orionis stars in quiescence, similar to HL Tau, their age and relative abundance imply that the FU Orionis phase occurs over a timescale of similar to 10(5) yr, and the quiescent phase between each outburst lasts similar to 10(3)-10(4) yr. These inferred properties are compatible with the scenario that FU Orionis outbursts are regulated by a thermal instability in the inner region of the disk. C1 UNIV TOKYO,DEPT ASTRON,BUNKYO KU,TOKYO 113,JAPAN. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. NOBEYAMA RADIO OBSERV,MINAMISA KU,NAGANO 38413,JAPAN. RP LIN, DNC (reprint author), UNIV CALIF SANTA CRUZ,LICK OBSERV,BOARD STUDIES ASTRON & ASTROPHYS,SANTA CRUZ,CA 95064, USA. NR 54 TC 34 Z9 34 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 NOV 10 PY 1994 VL 435 IS 2 BP 821 EP 828 DI 10.1086/174861 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ970 UT WOS:A1994PQ97000030 ER PT J AU LOCHNER, JC ROUSSELDUPRE, D AF LOCHNER, JC ROUSSELDUPRE, D TI RECURRENCE TIMES AND PERIODICITIES IN 4U-1608-52 AS OBSERVED BY VELA-5B SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, INDIVIDUAL (4U 1608-52); X-RAYS, BURSTS; X-RAYS, STARS ID X-RAY TRANSIENTS; IRRADIATED ACCRETION DISKS; AQUILA X-1; MODEL; INSTABILITY; SUPERHUMPS; EVOLUTION; PERIOD; BURSTS AB We report on the Vela 5B 10 year history of the soft X-ray transient 4U 1608-52, and on the characteristics of its soft X-ray outbursts. The Vela 5B satellite observed the four known outbursts in 1975, 1977, and 1979, and four new outbursts in 1970 and 1971, altering the recurrence pattern of outbursts from this source. One of the 1970 outbursts is symmetric in its intensity profile, while the two outbursts in 1971 have short exponential profiles separated by 80 days. Despite suggestive recurrence periods of similar to 85 and similar to 150 days evident in the time intervals between the outbursts, there is no single statistically significant recurrence time on which the outbursts recur consistently. In the 1970 symmetric event, there is evidence for a period of either 4.10 or 5.19 days. Drawing upon the analogy with SU Ursa Majoris dwarf novae, we suggest that the short period is orbital and any longer period would be associated with a precession period of the accretion disk. C1 LOS ALAMOS NATL LAB,ASTROPHYS & RADIAT MEASUREMENT GRP,LOS ALAMOS,NM 87545. UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP LOCHNER, JC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 6680,GREENBELT,MD 20771, USA. NR 38 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 1994 VL 435 IS 2 BP 840 EP 847 DI 10.1086/174863 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ970 UT WOS:A1994PQ97000032 ER PT J AU JUSTTANONT, K SKINNER, CJ TIELENS, AGGM AF JUSTTANONT, K SKINNER, CJ TIELENS, AGGM TI MOLECULAR ROTATIONAL LINE-PROFILES FROM OXYGEN-RICH RED GIANT WINDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; LINE, PROFILES; MOLECULAR PROCESSES; STARS, GIANTS; STARS, MASS LOSS ID MASS-LOSS RATES; CIRCUMSTELLAR DUST SHELLS; NEWTON-RAPHSON OPERATOR; OH-IR STARS; COMOVING-FRAME; EVOLVED STARS; CO EMISSION; SOBOLEV APPROXIMATION; INFRARED-EMISSION; CARBON-MONOXIDE AB We have developed a radiative transfer model of the dust and gas envelopes around late-type stars. The gas kinetic temperature for each star is calculated by solving equations of motion and the energy balance simultaneously. The main processes include viscous heating and adiabatic and radiative cooling. Heating is dominated by viscosity as the grains stream outward through the gas, with some contribution in oxygen-rich stars by near-IR pumping of H2O followed by collisional de-excitation in the inner envelope. For O-rich stars, rotational H2O cooling is a dominant mechanism in the middle part of the envelope, with CO cooling being less significant. We have applied our model to three well-studied oxygen-rich red giant stars. The three stars cover a wide range of mass-loss rates, and hence they have different temperature structures. The derived temperature structures are used in calculating CO line profiles for these objects. Comparison of the dust and gas mass-loss rates suggests that mass-loss rates are not constant during the asymptotic giant branch phase. In particular, the results show that the low CO 1-0 antenna temperatures of OH/IR stars reflect an earlier phase of much lower mass-loss rate. C1 UNIV LONDON UNIV COLL,DEPT PHYS & ASTRON,LONDON WC1E 6BT,ENGLAND. INST ASTROPHYS,F-75014 PARIS,FRANCE. LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94581. UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,JODRELL BANK,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. RP JUSTTANONT, K (reprint author), NASA,AMES RES CTR,MS245-3,MOFFETT FIELD,CA 94035, USA. OI /0000-0003-1689-9201 NR 39 TC 56 Z9 56 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 1994 VL 435 IS 2 BP 852 EP 863 DI 10.1086/174865 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ970 UT WOS:A1994PQ97000034 ER PT J AU GIRART, JM RODRIGUEZ, LF ANGLADA, G ESTALELLA, R TORRELLES, JM MARTI, J PENA, M AYALA, S CURIEL, S NORIEGACRESPO, A AF GIRART, JM RODRIGUEZ, LF ANGLADA, G ESTALELLA, R TORRELLES, JM MARTI, J PENA, M AYALA, S CURIEL, S NORIEGACRESPO, A TI AMMONIA DOWNSTREAM FROM HH-80-NORTH SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL, (HH 80 NORTH); ISM, JETS AND OUTFLOWS; ISM, MOLECULES; RADIO CONTINUUM, ISM ID HERBIG-HARO OBJECTS; RADIO-CONTINUUM EMISSION; MOLECULAR OUTFLOWS; PROTOSTELLAR DISK; GGD 27-IRS; REGIONS; SPECTROSCOPY; SYSTEM; DENSE; STAR AB HH 80-81 are two optically visible Herbig-Haro objects located about 5' south of their exciting source IRAS 18162-2048. Displaced symmetrically to the north of this luminous IRAS source, a possible HH counterpart was recently detected as a radio continuum source with the VLA. This radio source, HH 80 North, has been proposed to be a member of the Herbig-Haro class since its centimeter flux density, angular size, spectral index, and morphology are all similar to those of HH 80. However, no object has been detected at optical wavelengths at the position of HH 80 North, possibly because of high extinction, and the confirmation of the radio continuum source as an HH object has not been possible. In the prototypical Herbig-Haro objects HH 1 and 2, ammonia emission has been detected downstream of the how in both objects. This detection has been interpreted as a result of an enhancement in the ammonia emission produced by the radiation held of the shock associated with the HH object. In this Letter we report the detection of the (1, 1) and (2, 2) inversion transitions of ammonia downstream HH 80 North. This detection gives strong support to the interpretation of HH 80 North as a heavily obscured HH object. In addition, we suggest that ammonia emission may be a tracer of embedded Herbig-Haro objects in other regions of star formation. A 60 mu m IRAS source could be associated with HH 80 North and with the ammonia condensation. A tentative explanation for the far-infrared emission as arising in dust heated by the optical and UV radiation of the HH object is presented. C1 UNIV BARCELONA, DEPT ASTRON & METEOROL, BARCELONA, SPAIN. Univ Nacl Autonoma Mexico, INST ASTRON, MEXICO CITY, DF, MEXICO. NATL RADIO ASTRON OBSERV, SOCORRO, NM 87801 USA. IEC, SOC CATALANA FIS, ASTROFIS LAB, MADRID, SPAIN. CSIC, INST ASTROFIS ANDALUCIA, E-18080 GRANADA, SPAIN. CALTECH, JET PROP LAB, CTR INFRARED PROC & ANAL, PASADENA, CA 91125 USA. RP GIRART, JM (reprint author), HARVARD UNIV, SMITHSONIAN CTR ASTROPHYS, 60 GARDEN ST, MS 42, CAMBRIDGE, MA 02138 USA. RI Girart, Josep/O-1638-2014; OI Girart, Josep/0000-0002-3829-5591; Torrelles, Jose Maria/0000-0002-6896-6085 NR 31 TC 36 Z9 36 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 NOV 10 PY 1994 VL 435 IS 2 BP L145 EP L148 DI 10.1086/187615 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ973 UT WOS:A1994PQ97300017 ER PT J AU MARASCHI, L GRANDI, P URRY, CM WEHRLE, AE MADEJSKI, GM FINK, HH GHISELLINI, G HARTMAN, RC KORATKAR, AP VONMONTIGNY, C PIAN, E THOMAS, HC TREVES, A ALLER, MF ALLER, HD BAILYN, CD BALONEK, TJ BOCK, H COLLMAR, W GLASS, IS LITCHFIELD, SJ MCHARDY, IM MENDEZ, R PESCE, J REUTER, HP ROBSON, EI STEPPE, H STEVENS, JA TERASRANTA, H WAGNER, SJ AF MARASCHI, L GRANDI, P URRY, CM WEHRLE, AE MADEJSKI, GM FINK, HH GHISELLINI, G HARTMAN, RC KORATKAR, AP VONMONTIGNY, C PIAN, E THOMAS, HC TREVES, A ALLER, MF ALLER, HD BAILYN, CD BALONEK, TJ BOCK, H COLLMAR, W GLASS, IS LITCHFIELD, SJ MCHARDY, IM MENDEZ, R PESCE, J REUTER, HP ROBSON, EI STEPPE, H STEVENS, JA TERASRANTA, H WAGNER, SJ TI THE 1993 MULTIWAVELENGTH CAMPAIGN ON 3C-279 - THE RADIO TO GAMMA-RAY ENERGY-DISTRIBUTION IN LOW STATE SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES; ACTIVE; GALAXIES; INDIVIDUAL (3C 279); GALAXIES; JETS; GAMMA RAYS; OBSERVATIONS; QUASARS; GENERAL; ULTRAVIOLET; GALAXIES; X-RAYS; GALAXIES ID 3C-279; RADIATION; EMISSION; BLAZARS; QUASARS; MODEL AB Simultaneous observations of 3C 279 at radio, millimeter, near-infrared, optical, ultraviolet (with IUE) and X-ray (with ROSAT) wavelengths were obtained in 1992 December-1993 January, during a three week pointing at the source by the Compton Gamma Ray Observatory. The blazar was in a quiescent or ''low'' state during this period. Comparing the multiwavelenth energy distribution to that from 1991 June, when 3C 279 was in its brightest recorded gamma-ray state, we find the following: 1. 3C 279 faded dramatically at all frequencies above 10(14) Hz, while the flux variations at low frequencies (radio to millimeter wavelengths) were minor. 2. The near-infrared-optical-ultraviolet spectral shape was softer (steeper) in the quiescent state, and the X-ray spectra also appear softer, although the spectral indix measured by ROSAT refer to a lower energy band than that measured earlier with Ginga. 3. The ratio of the gamma-ray luminosity to that across ah other frequencies decreased from a value of similar or equal to 10 in the flaring state to a value similar or equal to 1 in the quiescent state. These findings imply that the production of gamma-rays is closely related to the optical-ultraviolet continuum, in agreement with models where gamma-rays are produced through inverse Compton (IC) scattering by relativistic electrons emitting the synchrotron continuum. The observed nonlinear relation between the synchrotron and IC requires both a change in the electron spectrum and an associated change in the seed photons. C1 UNIV MILAN,DEPT PHYS,I-20133 MILAN,ITALY. SPACE TELESCOPE EUROPEAN COORDINATING FACIL,D-85748 GARCHING,GERMANY. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. CALTECH,PASADENA,CA 91125. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. OSSERV ASTRON TORINO,I-10025 PINO TORINESE,ITALY. SISSA,ISAS,SCH ADV INT STUDIES,I-34014 TRIESTE,ITALY. MAX PLANCK INST ASTROPHYS,D-85740 GARCHING,GERMANY. UNIV MICHIGAN,DEPT PHYS & ASTRON,ANN ARBOR,MI 48109. YALE UNIV,DEPT ASTRON,NEW HAVEN,CT 06511. COLGATE UNIV,DEPT PHYS & ASTRON,HAMILTON,NY 13346. LANDESSTERNWARTE HEIDELBERG KONIGSSTUHL,D-69117 HEIDELBERG,GERMANY. S AFRICAN ASTRON OBSERV,CAPE TOWN 7935,SOUTH AFRICA. UNIV CENT LANCASHIRE,CTR ASTROPHYS,PRESTON PR1 2HE,LANCS,ENGLAND. UNIV SOUTHAMPTON,DEPT PHYS,SOUTHAMPTON SO9 5NH,HANTS,ENGLAND. IRAM,E-18012 GRANADA,SPAIN. METSAHOVI RADIO RES STN,SF-02540 KYLMALA,FINLAND. RP MARASCHI, L (reprint author), UNIV GENOA,DEPT PHYS,VIA DODECANESO 33,GENOA,ITALY. RI Urry, Claudia/G-7381-2011 OI Urry, Claudia/0000-0002-0745-9792 NR 25 TC 108 Z9 109 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 NOV 10 PY 1994 VL 435 IS 2 BP L91 EP L95 DI 10.1086/187602 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ973 UT WOS:A1994PQ97300004 ER PT J AU NEMIROFF, RJ NORRIS, JP BONNELL, JT WICKRAMASINGHE, WADT KOUVELIOTOU, C PACIESAS, WS FISHMAN, GJ MEEGAN, CA AF NEMIROFF, RJ NORRIS, JP BONNELL, JT WICKRAMASINGHE, WADT KOUVELIOTOU, C PACIESAS, WS FISHMAN, GJ MEEGAN, CA TI GROSS SPECTRAL DIFFERENCES BETWEEN BRIGHT AND DIM GAMMA-RAY BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY; THEORY; GAMMA-RAYS; BURSTS ID BATSE AB We find that dim gamma-ray bursts (GRBs) are softer than bright GRBs, as indicated on average by data from the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory. We show that this correlation is statistically significant with respect to variations due to random differences between GRBs. This effect is discernible using a variety of methods and data sets, including public domain data. We analyze several types of systematic errors and selection effects in the BATSE data and conclude that the observed effect is not dominated by any of them. We therefore assert that this dim/soft effect is a real property of GRBs. It is possible that this correlation is a consequence of the time dilation detected by Norris et al. (1994) and that the burst sources are located at cosmological distances. C1 GEORGE MASON UNIV,CSI INST,FAIRFAX,VA. UNIV SPACE RES ASSOC,WASHINGTON,DC. UNIV PENN,DEPT ASTRON,PHILADELPHIA,PA 19104. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,HUNTSVILLE,AL 35899. RP NEMIROFF, RJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. OI Nemiroff, Robert/0000-0002-4505-6599 NR 30 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 NOV 10 PY 1994 VL 435 IS 2 BP L133 EP L136 DI 10.1086/187612 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ973 UT WOS:A1994PQ97300014 ER PT J AU SWARTZ, DA ODELL, SL SULKANEN, ME TENNANT, AF AF SWARTZ, DA ODELL, SL SULKANEN, ME TENNANT, AF TI STATISTICAL UNCERTAINTIES IN TEMPERATURE DIAGNOSTICS FOR HOT CORONAL PLASMA USING THE ASCA SIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, CLUSTERING; METHODS, DATA ANALYSIS; X-RAYS, GENERAL AB Statistical uncertainties in determining the temperatures of hot (0.5-10 keV) coronal plasmas are investigated. The statistical precision of various spectral temperature diagnostics is established by analyzing synthetic ASCA solid-state imaging spectrometer (SIS) CCD spectra. The diagnostics considered are the ratio of hydrogen-like to helium-like line complexes of Z greater than or equal to 14 elements, line-free portions of the continuum, and the entire spectrum. While fits to the entire spectrum yield the highest statistical precision, it is argued that fits to the line-free continuum are less susceptible to atomic data uncertainties but lead to a modest increase in statistical uncertainty over full spectral fits. Temperatures deduced from line ratios can have similar accuracy, but only over a narrow range of temperatures. Convenient estimates of statistical accuracies for the various temperature diagnostics are provided which may be used in planning ASCA SIS observations. RP SWARTZ, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ASTROPHYS BRANCH,ES-84,HUNTSVILLE,AL 35812, USA. OI O'Dell, Stephen/0000-0002-1868-8056 NR 3 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 NOV 10 PY 1994 VL 435 IS 2 BP L149 EP L152 DI 10.1086/187616 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ973 UT WOS:A1994PQ97300018 ER PT J AU BEARD, JS LOFGREN, GE SINHA, AK TOLLO, RP AF BEARD, JS LOFGREN, GE SINHA, AK TOLLO, RP TI PARTIAL MELTING OF APATITE-BEARING CHARNOCKITE, GRANULITE, AND DIORITE - MELT COMPOSITIONS, RESTITE MINERALOGY, AND PETROLOGIC IMPLICATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID CENTRAL VIRGINIA; TRACE-ELEMENTS; BLUE RIDGE; FELDSPAR; MODEL; SR; BEHAVIOR; MAGMAS AB Melting experiments (P = 6.9 kbar, T = 850-950 degrees C, NNO50 for hibonite, LREE/HREE ratios of I in hibonite in some CTA CAI from Leoville and Allende are inconsistent with hibonite equilibrating with the melts that formed these inclusions and the hibonite is relict. Similar applications are possible with our perovskite partitioning data. For example, it is likely that high-REE (500-1000Xchondritic) perovskite with Th/U of 3-4 that are found in the outer region of Type BI CAI have not been in equilibrium with the CAI melt that contains similar to 20Xch REE and a Th/U ratio of 3 and they are probably relies that survived the most recent partial melting event. C1 CALTECH,DIV GEOL & PLANETARY SCI,CHARLES ARMS LAB,LUNAT ASYLUM,PASADENA,CA 91125. NASA,JOHNSON SPACE CTR,HOUSTON,TX 77058. RI WASSERBURG, GERALD /F-6247-2011; Kennedy, Allen/B-2425-2013 OI Kennedy, Allen/0000-0002-2132-7825 NR 33 TC 24 Z9 24 U1 2 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2541 J9 CHEM GEOL JI Chem. Geol. PD NOV 1 PY 1994 VL 117 IS 1-4 BP 379 EP 390 DI 10.1016/0009-2541(94)90139-2 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PW133 UT WOS:A1994PW13300022 ER PT J AU JIANG, BN SONNAD, V AF JIANG, BN SONNAD, V TI LEAST-SQUARES SOLUTION OF INCOMPRESSIBLE NAVIER-STOKES EQUATIONS WITH THE P-VERSION OF FINITE-ELEMENTS SO COMPUTATIONAL MECHANICS LA English DT Article ID FLUID-DYNAMICS; STRATEGY; FORMULATION; FLOW AB A p-version of the least-squares finite element method, based on the velocity-pressure-vorticity formulation, is developed for solving steady-state incompressible viscous flow problems. The resulting system of symmetric and positive definite linear equations can be solved satisfactorily with the conjugate gradient method. In conjunction with the use of rapid operator application which avoids the formation of both element and global matrices, it is possible to achieve a highly compact and efficient solution scheme for the incompressible Navier-Stokes equations. Numerical results are presented for two-dimensional flow over a backward-facing step. The effectiveness of simple outflow boundary conditions is also demonstrated. C1 IBM CORP,AUSTIN,TX 78758. RP JIANG, BN (reprint author), ICOMP,NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 30 TC 12 Z9 12 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0178-7675 J9 COMPUT MECH JI Comput. Mech. PD NOV PY 1994 VL 15 IS 2 BP 129 EP 136 PG 8 WC Mathematics, Interdisciplinary Applications; Mechanics SC Mathematics; Mechanics GA PU861 UT WOS:A1994PU86100003 ER PT J AU CHIEN, YP ECER, A AKAY, HU CARPENTER, F BLECH, RA AF CHIEN, YP ECER, A AKAY, HU CARPENTER, F BLECH, RA TI DYNAMIC LOAD BALANCING ON A NETWORK OF WORKSTATIONS FOR SOLVING COMPUTATIONAL FLUID-DYNAMICS PROBLEMS SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article AB Distributed computing on a network of computer workstations is being considered as a practical tool for parallel CFD applications. Presently, workstations are commonly arranged in the dedicated, single-user mode for executing such computations. Since workstations are generally employed in a multi-user environment, running the workstations in the dedicated mode causes scheduling problems for system administrators and inconvenience to other users. A methodology is presented in this paper for dynamic balancing of the computation load on a network of multi-user computers for parallel computing applications. In order to distribute the computation load in a multi-user environment, it becomes necessary to determine the effective speed of a multi-user workstation to a parallel application. In the present approach, it was assumed that (i) multi-user and multi-tasking networked computers may have different computation speeds, (ii) application data can be divided into many small data blocks with possibly different sizes, (iii) a process is assigned to each block, and (iv) the number of computers is much less than the number of processes. The developed dynamic load balancing procedure uses the greedy method for optimizing computation load distribution. Due to dynamic changes of the computer loads in a multi-user and multi-tasking environment, the loads on computers are periodically examined and parallel application processes may be re-distributed to reduce the computation time. The developed method has been tested on two computer clusters and its applicability has been demonstrated for two case studies. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP CHIEN, YP (reprint author), INDIANA UNIV PURDUE UNIV, SCH ENGN & TECHNOL, 723 W MICHIGAN ST, INDIANAPOLIS, IN 46202 USA. NR 13 TC 13 Z9 14 U1 0 U2 2 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0045-7825 J9 COMPUT METHOD APPL M JI Comput. Meth. Appl. Mech. Eng. PD NOV PY 1994 VL 119 IS 1-2 BP 17 EP 33 DI 10.1016/0045-7825(94)00074-3 PG 17 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA PV586 UT WOS:A1994PV58600003 ER PT J AU BROOKS, VL KEIL, LC AF BROOKS, VL KEIL, LC TI CHANGES IN THE BAROREFLEX DURING PREGNANCY IN CONSCIOUS DOGS - HEART-RATE AND HORMONAL RESPONSES SO ENDOCRINOLOGY LA English DT Article ID ATRIAL-NATRIURETIC-PEPTIDE; RENIN-ANGIOTENSIN SYSTEM; FEMALE RATS; BARORECEPTOR DENERVATION; ARTERIAL BARORECEPTORS; VASOPRESSIN SECRETION; PLASMA VASOPRESSIN; CORTISOL RESPONSES; STEROID-HORMONES; ACTH AB This study was performed to test the hypothesis that reflex increases in heart rate, PRA, and plasma concentrations of vasopressin, angiotensin-II, ACTH, and cortisol are reduced during pregnancy. The hypothesis was tested by measuring, in pregnant and nonpregnant conscious dogs, changes in arterial and atrial pressures, heart rate, and plasma hormone concentrations during 30-min infusions of three doses of nitroprusside (1, 2, and 4 mu g/kg.min). Between-group differences were determined by comparing the relationships between arterial or atrial pressure and plasma hormone concentrations. Hypotension-induced increases in heart rate and plasma levels of vasopressin, ACTH, and cortisol were blunted when the dogs were pregnant. In contrast, reflex increases in PRA and angiotensin-IJ were increased. These results indicate that the activity of the baroreceptor reflex is altered during pregnancy in dogs. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BROOKS, VL (reprint author), OREGON HLTH SCI UNIV,DEPT PHYSIOL,3181 SW JACKSON PK RD,PORTLAND,OR 97201, USA. FU NHLBI NIH HHS [HL-35872, HL-39923] NR 56 TC 25 Z9 25 U1 0 U2 1 PU ENDOCRINE SOC PI BETHESDA PA 4350 EAST WEST HIGHWAY SUITE 500, BETHESDA, MD 20814-4110 SN 0013-7227 J9 ENDOCRINOLOGY JI Endocrinology PD NOV PY 1994 VL 135 IS 5 BP 1894 EP 1901 DI 10.1210/en.135.5.1894 PG 8 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA PR667 UT WOS:A1994PR66700024 PM 7956910 ER PT J AU GREEN, NR FERRANDO, AA AF GREEN, NR FERRANDO, AA TI PLASMA BORON AND THE EFFECTS OF BORON SUPPLEMENTATION IN MALES SO ENVIRONMENTAL HEALTH PERSPECTIVES LA English DT Article; Proceedings Paper CT International Symposium on Health Effects of Boron and Its Compounds CY SEP 16-17, 1992 CL UNIV CALIF IRVINE, IRVINE, CA HO UNIV CALIF IRVINE DE BORON; TESTOSTERONE; BODYBUILDERS; MICROWAVE DIGESTION; BLOOD BORON ID BIOLOGICAL-MATERIALS; STRENGTH; DIGESTION; RESPONSES; HORMONES; LITHIUM; MASS AB Recently, a proliferation of athletic supplements has been marketed touting boron as an ergogenic aid capable of increasing testosterone. The effect of boron supplementation was investigated in male bodybuilders. Ten male bodybuilders (aged 20 to 26) were given a 2.5-mg boron supplement, while nine male bodybuilders (aged 21 to 27) were given a placebo for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on day 1 and day 49 of the study. A microwave digestion procedure followed by inductively coupled argon plasma spectroscopy was used for boron determination. Twelve subjects had boron values at or above the detection limit with median value of 25 ng/ml (16 ng/ml lower quartile and 33 ng/ml upper quartile). Of the ten subjects receiving boron supplements, six had an increase in their plasma boron. Analysis of variance indicated no significant effect of boron supplementation on any of the other dependent variables. Both groups demonstrated significant increases in total testosterone (p<0.01), lean body mass (p<0.01), and one repetition maximum (RM) squat (p<0.001) and one RM bench press (p<0.01). The findings suggest that 7 weeks of bodybuilding can increase total testosterone, lean body mass. and strength in lesser-trained bodybuilders, but boron supplementation affects these variables not at all. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP GREEN, NR (reprint author), AUBURN UNIV,DEPT NUTR & FOOD SCI,328 SPIDLE HALL,AUBURN,AL 36849, USA. NR 17 TC 12 Z9 13 U1 0 U2 0 PU NATL INST ENVIRON HEALTH SCI PI RES TRIANGLE PK PA PO BOX 12233, RES TRIANGLE PK, NC 27709 SN 0091-6765 J9 ENVIRON HEALTH PERSP JI Environ. Health Perspect. PD NOV PY 1994 VL 102 SU 7 BP 73 EP 77 DI 10.2307/3431966 PG 5 WC Environmental Sciences; Public, Environmental & Occupational Health; Toxicology SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health; Toxicology GA PY063 UT WOS:A1994PY06300012 PM 7889885 ER PT J AU PIASCIK, RS WILLARD, SA AF PIASCIK, RS WILLARD, SA TI THE GROWTH OF SMALL CORROSION-FATIGUE CRACKS IN ALLOY-2024 SO FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES LA English DT Article AB The corrosion fatigue crack growth characteristics of small surface and corner cracks in aluminium alloy 2024 is established. The damaging effect of salt water on the early stages of small crack growth is characterized by: (1) crack initiation at constituent particle pits, (2) intergranular microcracking for alpha less than or equal to 100 mu m, and (3) transgranular small crack growth for alpha greater than or equal to 100 mu m. In aqueous 1% NaCl and at a constant anodic potential of -700 mV(SCE), small cracks exhibit a factor of three increase in fatigue crack growth rates compared to laboratory air. Small cracks exhibit accelerated corrosion fatigue crack growth rates at low levels of Delta K (< 1 MPa root m) below the long crack Delta K-th value. When exposed to Paris regime levels of crack tip stress intensity, small corrosion fatigue cracks exhibit growth rates similar to that observed for long cracks. Similar small and long crack growth behavior at various levels of R suggest that crack closure effects influence the corrosion fatigue crack growth rates of small cracks for alpha greater than or equal to 100 mu m. Contrary to the corrosion fatigue characteristics of small cracks in high strength steels, no pronounced chemical crack length effect is observed for alloy 2024 exposed to salt water. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP PIASCIK, RS (reprint author), NASA,LANGLEY RES CTR,MECH MAT BRANCH,HAMPTON,VA 23681, USA. NR 31 TC 38 Z9 40 U1 0 U2 5 PU FATIGUE & FRACTURE ENGINEERINGMATERIALS STRUCTURES LIMITED PI SHEFFIELD PA C/O SIRIUS UNIV OF SHEFFIELD/FAC OF ENG MAPPIN STREET, SHEFFIELD, S YORKSHIRE, ENGLAND S1 3JD SN 8756-758X J9 FATIGUE FRACT ENG M JI Fatigue Fract. Eng. Mater. Struct. PD NOV PY 1994 VL 17 IS 11 BP 1247 EP 1259 PG 13 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA PT679 UT WOS:A1994PT67900001 ER PT J AU SMITH, DE KOLENKIEWICZ, R NEREM, RS DUNN, PJ TORRENCE, MH ROBBINS, JW KLOSKO, SM WILLIAMSON, RG PAVLIS, EC AF SMITH, DE KOLENKIEWICZ, R NEREM, RS DUNN, PJ TORRENCE, MH ROBBINS, JW KLOSKO, SM WILLIAMSON, RG PAVLIS, EC TI CONTEMPORARY GLOBAL HORIZONTAL CRUSTAL MOTION SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE PLATE TECTONICS; SATELLITE LASER RANGING; SPACE GEODESY ID WESTERN UNITED-STATES; PLATE MOTIONS; ACTIVE TECTONICS; DEFORMATION; REGION; LAGEOS; NORTH; SEA AB An analysis of Satellite Laser Ranging (SLR) data to the LAGEOS satellite has yielded improved estimates of the horizontal motion for a subset of 34 tracking sites, within the global tracking network. The analysis, called SL8.3, utilized data acquired between 1980 January and 1993 June by the global network composed of 71 sites. The solution design provides for the simultaneous estimation of site positions and their velocities within a pre-defined kinematic frame. The solution is statistically rigorous and retains the full correlation information content. Least-squares estimates of relative poles of rotation, which are used to model the motion of one plate relative to another, were made based on the SLR estimated velocities for sites known to be well away from deformation zones. The resulting SLR-based relative rotation poles differ slightly from those of NUVEL-1, but in general, indicate that the magnitude of the SLR implied velocities is slower than those implied by NUVEL-1, consistent with the 4-5 per cent slowing in relative spherical rates noted in earlier comparisons. Spherical rates between sites in western North America support models of extension in the Basin and Range Province and the rotation of the Sierra Nevada microplate. An analysis of the spherical rates crossing the North Atlantic shows that SL8.3 estimated extension between North America-Eurasia sites is generally smaller than those implied by NUVEL-1; meanwhile SL8.3 rates between North America-Africa sites are in better agreement with NUVEL-1, although they are not so well determined. The maintenance and ongoing monitoring of global SLR site kinematics provides a well-defined global reference which will aid in combination global kinematic solutions where information from other technologies are merged (e.g. Very Long Baseline Interferometry and Global Positioning System) and in providing the context for densification studies of regional kinematics derived from terrestrial and Global Positioning System observations. C1 HUGHES STX CORP, GREENBELT, MD 20770 USA. NASA, GODDARD SPACE FLIGHT CTR, UNIV MARYLAND, DEPT ASTRON, GREENBELT, MD 20771 USA. RP SMITH, DE (reprint author), NASA, GODDARD SPACE FLIGHT CTR, TERR PHYS LAB, GREENBELT, MD 20771 USA. NR 27 TC 25 Z9 25 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD NOV PY 1994 VL 119 IS 2 BP 511 EP 520 DI 10.1111/j.1365-246X.1994.tb00138.x PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PR074 UT WOS:A1994PR07400011 ER PT J AU TREPTE, CR THOMASON, LW KENT, GS AF TREPTE, CR THOMASON, LW KENT, GS TI BANDED STRUCTURES IN STRATOSPHERIC AEROSOL DISTRIBUTIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID II MEASUREMENTS; SAGE; SATELLITE; MASS AB Zonal bands of stratospheric aerosol optical depth are observed by various sensors under both volcanic and non-volcanic conditions. Maximum optical depths occur within the tropics and at high latitudes, while minima are found between latitudes of approximately 15-degrees and 45-degrees. This structure is shown to result from a reservoir of aerosol over the tropics, poleward transport, and the departure of the tropopause from isentropic surfaces. C1 SCI & TECHNOL CORP,HAMPTON,VA 23666. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP TREPTE, CR (reprint author), SCI APPLICAT INT CORP,HAMPTON,VA 23666, USA. OI Thomason, Larry/0000-0002-1902-0840 NR 16 TC 31 Z9 33 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 NOV 1 PY 1994 VL 21 IS 22 BP 2397 EP 2400 DI 10.1029/94GL01462 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PQ432 UT WOS:A1994PQ43200015 ER PT J AU MANNEY, GL ZUREK, RW GELMAN, ME MILLER, AJ NAGATANI, R AF MANNEY, GL ZUREK, RW GELMAN, ME MILLER, AJ NAGATANI, R TI THE ANOMALOUS ARCTIC LOWER STRATOSPHERIC POLAR VORTEX OF 1992-1993 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OZONE AB Potential vorticity (PV) gradients defining the lower stratospheric vortex during the 1992-1993 winter were anomalously strong and persistent compared to those during the last 16 Arctic winters. For almost-equal-to3 months PV gradients were closer to typical Antarctic values than to most Arctic values. Air motion diagnostics computed for 3-dimensional air parcel trajectories confirm that the 1992-1993 Arctic lower stratospheric vortex was substantially more isolated than is typical. Such isolation will delay and reduce the export of the higher ozone typical of the winter lower stratospheric vortex to mid-latitudes. This may have contributed to the record-low total ozone amounts observed in northern mid-latitudes in 1993. C1 NOAA,NATL WEATHER SERV,NATL METEOROL CTR,WASHINGTON,DC 20233. RP MANNEY, GL (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 13 TC 50 Z9 50 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 1994 VL 21 IS 22 BP 2405 EP 2408 DI 10.1029/94GL02368 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PQ432 UT WOS:A1994PQ43200017 ER PT J AU REDDY, CA HOEGY, WR PESNELL, WD MAYR, HG HINES, CO AF REDDY, CA HOEGY, WR PESNELL, WD MAYR, HG HINES, CO TI ACCURACY OF O+-O COLLISION CROSS-SECTION DEDUCED FROM IONOSPHERE-THERMOSPHERE OBSERVATIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DENSITIES; FREQUENCY AB Aeronomic observations applied to the empirical derivation of the ion-neutral collision cross-section-a basic parameter governing the mutual interactions between the neutral and plasma components in the Earth's upper atmosphere-have given values considerably larger than those derived from theory. The empirical scheme uses the plasma velocities obtained with the Incoherent Scatter Radar and the neutral winds obtained with the Fabry-Perot Interferometer. It is shown here that such an analysis overestimates the collision cross-section due to the effects of errors in the observables. The effect may be sufficiently large to bring about agreement with theory, and calls for a re-analysis of the aeronomic data using methods which minimize the bias caused by measurement errors. RP REDDY, CA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHER BRANCH,CODE 914,GREENBELT,MD 20771, USA. RI Pesnell, William/D-1062-2012 OI Pesnell, William/0000-0002-8306-2500 NR 13 TC 16 Z9 15 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 NOV 1 PY 1994 VL 21 IS 22 BP 2429 EP 2432 DI 10.1029/94GL02494 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PQ432 UT WOS:A1994PQ43200023 ER PT J AU HOGAN, KB HARRISS, RC AF HOGAN, KB HARRISS, RC TI A DRAMATIC DECREASE IN THE GROWTH-RATE OF ATMOSPHERIC METHANE IN THE NORTHERN-HEMISPHERE DURING 1992 - COMMENT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Note C1 NASA,MISSION PLANET EARTH,WASHINGTON,DC 20546. RP HOGAN, KB (reprint author), US EPA,DIV GLOBAL CHANGE 6202J,401 M ST SW,WASHINGTON,DC 20460, USA. NR 14 TC 30 Z9 31 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 NOV 1 PY 1994 VL 21 IS 22 BP 2445 EP 2446 DI 10.1029/94GL02601 PG 2 WC Geosciences, Multidisciplinary SC Geology GA PQ432 UT WOS:A1994PQ43200027 ER PT J AU SMREKAR, SE AF SMREKAR, SE TI EVIDENCE FOR ACTIVE HOTSPOTS ON VENUS FROM ANALYSIS OF MAGELLAN GRAVITY-DATA SO ICARUS LA English DT Article ID BETA-REGIO; ISOSTATIC COMPENSATION; APHRODITE TERRA; HOT-SPOT; THERMAL-GRADIENT; MANTLE PLUMES; EISTLA REGIO; GEOID HEIGHT; ATLA-REGIO; TECTONICS AB The 500-Myr average crater retention age for Venus has raised questions about the present-day level of tectonic activity. In this study we examine the relationship between the gravity and topography of four large volcanic swells, Beta, Atla, Bell, and Western Eistla Regiones, for clues about their stage of evolution. The Magellan line-of-sight gravity data are inverted using a point mass model of the anomalous mass to solve for the local vertical gravity field. Spectral admittance calculated from both the local gravity inversions and a spherical harmonic model is compared to three models of compensation: local compensation, a ''flexural'' model with local and regional compensation of surface and subsurface loads, and a ''hotspot'' model of compensation that includes top loading by volcanoes and subsurface loading due to a deep, low density mass anomaly. The coherence is also calculated in each region, but yields an elastic thickness estimate only at Bell Regio. In all models, the long wavelengths are compensated locally. The long-wavelength estimates of the deep compensation depth for Bell, Atla, Western Eistla, and Beta Regiones are 125, 175, 200, and 225 km, respectively, with an error of approximately +/- 35 km. The flexural model is rejected primarily because it gives values of effective elastic thickness of approximately 100 km, which is at least a factor of two larger than estimates of effective elastic thickness obtained from the coherence spectra at Bell Regio and from other studies that model the topographic expression of flexure at Bell Regio and in other tectonic settings globally. Assuming a crustal thickness of 30 km, the fit to the hotspot model at Atla Regio gives an effective elastic thickness of 30 +/- 5 km. Atla Regio is interpreted as an active hotspot because of the deep compensation depth and a strong subsurface loading signature. At Bell Regio, effective elastic thickness is 30 +/- 5 km at short wavelengths and 50 +/- 5 km at long wavelengths, using a crustal thickness of 10 km. The 30-km value is interpreted as the effective elastic thickness at the time when the volcanoes are emplaced; the 50-km value is believed to reflect the present-day effective elastic thickness. Bell Regio has a relatively shallow compensation depth, 125 km, and a weak bottom-to-top-loading ratio determined from the coherence spectra. These results may indicate a relatively old, possibly inactive plume. The data at Beta and Western Eistla Regiones are of relatively poor quality and do not permit detailed interpretations. These areas are interpreted as active hotspots because of their large compensation depths, greater than typical of the rest of the planet. (C) 1994 Academic Press, Inc. RP SMREKAR, SE (reprint author), CALTECH,JET PROP LAB,MS 183-501,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 90 TC 56 Z9 57 U1 2 U2 4 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1994 VL 112 IS 1 BP 2 EP 26 DI 10.1006/icar.1994.1166 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QC943 UT WOS:A1994QC94300002 ER PT J AU RAPPAPORT, N PLAUT, JJ AF RAPPAPORT, N PLAUT, JJ TI A 360-DEGREE AND 360-ORDER MODEL OF VENUS TOPOGRAPHY SO ICARUS LA English DT Article ID GRAVITY AB This report presents the most recent spherical harmonic topography model of Venus developed at Jet Propulsion Laboratory. It was produced by a spherical harmonic analysis of the most complete set of Magellan altimetry data, augmented by Pioneer Venus and Venera data. The harmonic coefficients of the topography were computed to degree and order 360. Compared to previous topography models, this one has the highest correlation with the gravity field of Venus. (C) 1994 Academic Press, Inc. RP RAPPAPORT, N (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 26 Z9 27 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1994 VL 112 IS 1 BP 27 EP 33 DI 10.1006/icar.1994.1167 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QC943 UT WOS:A1994QC94300003 ER PT J AU KONOPLIV, AS SJOGREN, WL AF KONOPLIV, AS SJOGREN, WL TI VENUS SPHERICAL HARMONIC GRAVITY MODEL TO DEGREE-60 AND ORDER-60 SO ICARUS LA English DT Article ID TOPOGRAPHY AB The Magellan and Pioneer Venus Orbiter radiometric tracking data sets have been combined to produce a 60th degree and order spherical harmonic gravity field. The Magellan data include the high-precision X-band gravity tracking from September 1992 to May 1993 and post-aerobraking data up to January 5, 1994. Gravity models are presented from the application of Kaula's power rule for Venus and an alternative a priori method using surface accelerations. Results are given as vertical gravity acceleration at the reference surface, geoid, vertical Bouguer, and vertical isostatic maps with errors for the vertical gravity and geoid maps included. Correlation of the gravity with topography for the different models is also discussed. (C) 1994 Academic Press, Inc. RP KONOPLIV, AS (reprint author), CALTECH,JET PROP LAB,MAIL STOP 301-125J,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 44 Z9 45 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1994 VL 112 IS 1 BP 42 EP 54 DI 10.1006/icar.1994.1169 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QC943 UT WOS:A1994QC94300005 ER PT J AU BANERDT, WB KONOPLIV, AS RAPPAPORT, NJ SJOGREN, WL GRIMM, RE FORD, PG AF BANERDT, WB KONOPLIV, AS RAPPAPORT, NJ SJOGREN, WL GRIMM, RE FORD, PG TI THE ISOSTATIC STATE OF MEAD CRATER SO ICARUS LA English DT Article ID VISCOUS RELAXATION; HARMONIC-ANALYSIS; IMPACT CRATERS; VENUS GRAVITY; MARS; MODEL; TOPOGRAPHY; CONSTRAINTS; THICKNESS; MAGELLAN AB We have analyzed high-resolution Magellan Doppler tracking data over Mead crater, using both line-of-sight and spherical harmonic methods, and have found a negative gravity anomaly of about 4-5 mgal (at spacecraft altitude, 182 km). This is consistent with no isostatic compensation of the present topography; the uncertainty in the analysis allows perhaps as much as 30% compensation at shallow depths (similar to 25 km). This is similar to observations of large craters on Earth, which are not generally compensated, but contrasts with at least some lunar basins which are inferred to have large Moho uplifts and corresponding positive Bouguer anomalies. An uncompensated load of this size requires a lithosphere with an effective elastic lithosphere thickness greater than 30 km. In order for the crust-mantle boundary not to have participated in the deformation associated with the collapse of the transient cavity during the creation of the crater, the yield strength near the top of the mantle must have been significantly higher on Earth and Venus than on the Moon at the time of basin formation. This might be due to increased strength against frictional sliding at the higher confining pressures within the larger planets. Alternatively, the thinner crusts of Earth and Venus compared to that of the Moon may result in higher creep strength of the upper mantle at shallower depths. (C) 1994 Academic Press,Inc. C1 ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. RP BANERDT, WB (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. OI Grimm, Robert/0000-0002-7588-1194 NR 45 TC 6 Z9 6 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1994 VL 112 IS 1 BP 117 EP 129 DI 10.1006/icar.1994.1173 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QC943 UT WOS:A1994QC94300009 ER PT J AU ARVIDSON, RE BRACKETT, RA SHEPARD, MK IZENBERG, NR FEGLEY, B PLAUT, JJ AF ARVIDSON, RE BRACKETT, RA SHEPARD, MK IZENBERG, NR FEGLEY, B PLAUT, JJ TI MICROWAVE SIGNATURES AND SURFACE-PROPERTIES OF OVDA-REGIO AND SURROUNDINGS, VENUS SO ICARUS LA English DT Article ID MAGELLAN; EMISSION AB Magellan observations of horizontally and vertically polarized emissivity and radar specific cross sections are jointly modeled to separate dielectric constants from textural effects for lobate plains, fractured plains, fracture belts, festoon flows, and tessera in Ovda Regio and surroundings. The model assumes surface emission and scattering dominate and that signatures are controlled by a combination of quasi-specular and diffuse-scale mechanisms. Textural parameters are found to correlate with geology whereas dielectric constants are found to depend on elevation. A gradual increase in dielectric constant from rock-like values (4 to 5) to a value of approximately 50 is evident over the interval from 6054 to 6056 km, where elevations are derived from Magellan altimetry observations. Stereo radargrammetric analyses demonstrate that a return to rock-like values occurs over approximately 0.5 km above the terrain with highest dielectric constants. The abrupt return to rocklike values occurs independently of geology and reinforces the hypothesis of elevation control on dielectric constant values. Variations in dielectric constant with elevation are modeled using an 1000-ppm concentration of a ferroelectric mineral with a Curie temperature of 707 K. The model reproduces the abrupt change at highest elevations, as the Curie temperature is reached, and the gradual change as lower elevations are encountered. To our knowledge no other model explains the trends with such simplicity. (C) 1994 Academic Press, Inc. C1 WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,ST LOUIS,MO 63130. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ARVIDSON, RE (reprint author), WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130, USA. RI Izenberg, Noam/F-3952-2015 OI Izenberg, Noam/0000-0003-1629-6478 NR 39 TC 9 Z9 9 U1 1 U2 4 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1994 VL 112 IS 1 BP 171 EP 186 DI 10.1006/icar.1994.1176 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QC943 UT WOS:A1994QC94300012 ER PT J AU WEITZ, CM PLAUT, JJ GREELEY, R SAUNDERS, RS AF WEITZ, CM PLAUT, JJ GREELEY, R SAUNDERS, RS TI DUNES AND MICRODUNES ON VENUS - WHY WERE SO FEW FOUND IN THE MAGELLAN DATA SO ICARUS LA English DT Article ID IMAGING RADAR OBSERVATIONS; SAND DUNES; SURFACE; MARS; SPACEBORNE; FEATURES; WIND AB A search through cycle 1, 2, and 3 Magellan radar data covering 98% of the surface of Venus revealed very few dunes. Only two possible dune fields and several areas that may contain microdunes smaller than the resolution of the images (75 m) were identified. The Aglaonice dune field was identified in the cycle 1 images by the specular returns characteristic of dune faces oriented perpendicular to the radar illumination. Cycle 1 and 2 data of the Fortuna-Meshkenet dune field indicate that there has been no noticeable movement of the dunes over an 8-month period. The dunes, which are oriented both parallel and perpendicular to the radar illumination, appear to be dark features on a brighter substrate. Bright and dark patches that were visible in either cycle 1 or 2 data, but not both, allowed identification of several regions in the southern part of Venus that may contain microdunes. The microdunes are associated with several parabolic crater deposits in the region and are probably similar to those formed in wind tunnel experiments under Venus-like conditions, Bragg scattering and/or subpixel reflections from the near-normal face on asymmetric microdunes may account for these bright and dark patches. Look-angle effects and the lack of sufficient sand-size particles seem to be the most likely reasons so few dunes were identified in Magellan data. Insufficient wind speeds, thinness of sand cover, and difficulty in identifying isolated dunes may also be contributors to the scarcity of dunes. (C) 1994 Academic Press, Inc. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. RP WEITZ, CM (reprint author), BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912, USA. NR 25 TC 16 Z9 17 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1994 VL 112 IS 1 BP 282 EP 295 DI 10.1006/icar.1994.1181 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QC943 UT WOS:A1994QC94300017 ER PT J AU BRANDHORST, HW AF BRANDHORST, HW TI SPACE POWER - WHATS OLD IS NEW AGAIN SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB The nation is presently seeking smaller and faster space missions that cost less. Furthermore, there is pressure to spin off technologies into the commercial sector as well as spin in technologies to the space program. In this environment, ideas that were dismissed in the past have come to the forefront again. This paper discusses high performance photovoltaic devices, solar dynamic systems, new batteries and power management and distribution schemes. Spin offs of power technologies are impacting aeronautical, terrestrial and naval applications as well. It is believed that interactions with terrestrial commercial industries will lead to deeper understandings of how to reduce space costs as well as increasing quality and reliability. RP BRANDHORST, HW (reprint author), NASA,LEWIS RES CTR,DIV POWER TECHNOL,CLEVELAND,OH 44135, USA. NR 2 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 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD NOV PY 1994 VL 9 IS 11 BP 21 EP 25 DI 10.1109/62.329556 PG 5 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA PR887 UT WOS:A1994PR88700004 ER PT J AU DAVARIAN, F ROBBINS, PE AF DAVARIAN, F ROBBINS, PE TI SPECTRUM ALLOCATIONS FOR MOBILE-SATELLITE SERVICES SO IEEE COMMUNICATIONS MAGAZINE LA English DT Article RP DAVARIAN, F (reprint author), JET PROP LAB,PASADENA,CA 91109, 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 0163-6804 J9 IEEE COMMUN MAG JI IEEE Commun. Mag. PD NOV PY 1994 VL 32 IS 11 BP 19 EP & PG 0 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA PR108 UT WOS:A1994PR10800004 ER PT J AU WU, TK LEE, SW AF WU, TK LEE, SW TI MULTIBAND FREQUENCY-SELECTIVE SURFACE WITH MULTIRING PATCH ELEMENTS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB Theoretical discussions and experimental verifications are presented for a multiband frequency selective surface (FSS) with perfectly conducting multiring patch elements. It is found that the narrow-ring approximation is valid for a ring width less than 0.025 lambda with lambda being the wavelength of the FSS's resonant frequency. A single screen double-ring element FSS is demonstrated for (1) a low-pass FSS that reflects the Ka-band signal while passing the S-,X-, and Ku-band signals, and (2) a tri-band system that reflects the X-band signal while transmitting through the S- and Ku-band signals. In addition, a double screen four-band PSS with non-similar double-ring elements is developed by cascading the above mentioned two single screens. The good agreement obtained between the measured and the computed results verified the computer codes and the approaches of this paper. C1 UNIV ILLINOIS,DEPT ELECT & COMP ENGN,URBANA,IL 61801. RP WU, TK (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 80 Z9 83 U1 1 U2 9 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 NOV PY 1994 VL 42 IS 11 BP 1484 EP 1490 DI 10.1109/8.362790 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA PY614 UT WOS:A1994PY61400004 ER PT J AU PARSONS, CL WALSH, EJ VANDEMARK, DC AF PARSONS, CL WALSH, EJ VANDEMARK, DC TI TOPOGRAPHIC MAPPING USING A MULTIBEAM RADAR ALTIMETER SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB An airborne radar altimeter operating at 36 GHz is uniquely capable of measuring the topography of mater, land, and ice surfaces. The Multimode Airborne Radar Altimeter (MARA) was designed to combine a narrow transmitted pulsewidth, a high transmitted power level, and a narrow antenna beam to produce a high-precision ranging capability at the nadir of the aircraft platform and at four fixed off-nadir angles out to 12 degrees in the multibeam mode described in this paper, or a single beam scanning between +/-22 degrees in the scanning radar altimeter mode. Data collected over mater and land surfaces are presented to demonstrate the potential of MARA for topographic mapping with accuracies and precisions of value in dynamic oceanography, geodesy, geology, hydrology, biogeochemistry, biogeography, and glaciology. C1 MCDONNELL DOUGLAS HELICOPTER CO,MESA,AZ. RP PARSONS, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337, USA. NR 10 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 1994 VL 32 IS 6 BP 1170 EP 1178 DI 10.1109/36.338365 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 PY306 UT WOS:A1994PY30600006 ER PT J AU ZINK, M OTTL, H FREEMAN, A AF ZINK, M OTTL, H FREEMAN, A TI DESIGN OF A MONOPULSE SAR SYSTEM FOR THE DETERMINATION OF ELEVATION ANGLES SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Note DE SYNTHETIC APERTURE RADAR (SAR); RADIOMETRIC CORRECTIONS; MONOPULSE; TOPOGRAPHIC MAPPING ID CALIBRATION AB Terrain height variations in mountainous areas cause problems in the radiometric correction of SAR images. We propose a novel SAR system which exploits the monopulse principle to determine the elevation angle and thus the height at the different parts of the image. From the ratios of images radiometrically modulated by the difference and sum antenna pattern in cross-track direction, we can calculate the appropriate elevation angle at any point in the image. In this paper, we present design considerations for an array antenna for DLR's airborne X-Band SAR system and give estimates of the error due to system noise and azimuth ambiguities as well as the expected performance and precision in topographic mapping. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ZINK, M (reprint author), GERMAN AEROSP RES ESTAB,INST RADIO FREQUENCY TECHNOL,DLR,D-82234 OBERPFAFFENHOFEN,GERMANY. NR 16 TC 1 Z9 1 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 NOV PY 1994 VL 32 IS 6 BP 1198 EP 1201 DI 10.1109/36.338371 PG 4 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA PY306 UT WOS:A1994PY30600011 ER PT J AU KATTI, RR AF KATTI, RR TI SPACE DATA-STORAGE SYSTEMS AND TECHNOLOGIES SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 6th Joint Magnetism and Magnetic Materials-Intermag Conference CY JUN 20-23, 1994 CL ALBUQUERQUE, NM SP AMER INST PHYS, IEEE, MAGNET SOC, MINERALS MET & MAT SOC, AMER SOC TESTING & MAT, USN, OFF NAVAL RES, AMER CERAM SOC ID MEMORY AB The acquisition and transmission from space to Earth of data is the central part of many space missions. A data storage subsystem, based on a data storage technology, is typically used to buffer data from the spacecraft and its instruments before data are returned to Earth. Because of requirements, constraints, and the design of the mission, the selection of the appropriate data storage technology for this function is based on many considerations, such as reliability, readiness, availability, mass, volume, power consumption, capacity, data rate, nonvolatility, environmental stability, radiation insensitivity, vibration insensitivity, data management flexibility, and cost, among other. Here, issues are review for space data storage technologies, including magnetic tape recording and solid-state memories, for past, present, and future missions, such as Voyager, Cassini, and Pluto Flyby. RP KATTI, RR (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 54 TC 1 Z9 1 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 NOV PY 1994 VL 30 IS 6 BP 4194 EP 4199 DI 10.1109/20.334033 PN 1 PG 6 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA PU429 UT WOS:A1994PU42900130 ER PT J AU NATH, S WINCHESKI, B FULTON, JP NAMKUNG, M AF NATH, S WINCHESKI, B FULTON, JP NAMKUNG, M TI STUDS OF THE NEW EDDY-CURRENT NONDESTRUCTIVE TESTING SENSOR ON FERROMAGNETIC MATERIALS SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 6th Joint Magnetism and Magnetic Materials-Intermag Conference CY JUN 20-23, 1994 CL ALBUQUERQUE, NM SP AMER INST PHYS, IEEE, MAGNET SOC, MINERALS MET & MAT SOC, AMER SOC TESTING & MAT, USN, OFF NAVAL RES, AMER CERAM SOC AB A new eddy current non-destructive testing (NDT) sensor developed at NASA Langley Research Center can accurately detect fatigue cracks and measure material and non-conducting coating thicknesses. This paper presents experimental and finite element modeling data on the characteristics of the sensor on ferromagnetic materials Fatigue crack detection and lift-off characteristics in steel and aluminum are compared and discussed. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. RP NATH, S (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. RI Namkung, Min/E-1533-2012 NR 6 TC 4 Z9 4 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD NOV PY 1994 VL 30 IS 6 BP 4644 EP 4646 DI 10.1109/20.334172 PN 1 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA PU429 UT WOS:A1994PU42900274 ER PT J AU SANGER, TD AF SANGER, TD TI OPTIMAL UNSUPERVISED MOTOR LEARNING FOR DIMENSIONALITY REDUCTION OF NONLINEAR CONTROL-SYSTEMS SO IEEE TRANSACTIONS ON NEURAL NETWORKS LA English DT Article ID ARM MOVEMENTS; NEURAL NETWORK; VISUAL TARGETS; DIRECTION; CORTEX; SPACE AB In this paper, optimal unsupervised motor learning is defined to be a technique for finding the coordinate system of minimum dimensionality which can adequately describe a particular motor task. An explicit method is provided for learning a stable controller that translates commands within the new coordinate system into motor variables appropriate for plant control. The method makes use of previously described Neural Network algorithms including the Generalized Hebbian Algorithm [1], Basis-Function Trees [2], and Trajectory Extension Learning [3]. Examples of applications to a real direct-drive two joint planar robot arm and a simulated three joint robot arm with visual sensing are given. RP SANGER, TD (reprint author), CALTECH,JET PROP LAB,NASA,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 35 TC 11 Z9 11 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 1045-9227 J9 IEEE T NEURAL NETWOR JI IEEE Trans. Neural Netw. PD NOV PY 1994 VL 5 IS 6 BP 965 EP 973 DI 10.1109/72.329694 PG 9 WC Computer Science, Artificial Intelligence; Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA PQ763 UT WOS:A1994PQ76300011 PM 18267871 ER PT J AU WOOD, JC BARRY, DT AF WOOD, JC BARRY, DT TI RADON TRANSFORMATION OF TIME-FREQUENCY DISTRIBUTIONS FOR ANALYSIS OF MULTICOMPONENT SIGNALS SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article ID DISCRETE-TIME; WIGNER DISTRIBUTIONS AB The Radon transform of a time-frequency distribution produces local areas of signal concentration that facilitate interpretation of multicomponent signals. The Radon-Wigner transform can be efficiently implemented with dechirping in the time domain, however, only half of the possible projections through the time-frequencpy plane can be realized because of aliasing. We show here that the frequency dual to dechirping exists, so that all of the time-frequency plane projections can be calculated efficiently. Both time and frequency dechirping are shown to warp the time-frequency plane rather rotating it, producing an angle dependent dilation of the Radon-Wigner projection axis. We derive the discrete-time equations for both time and frequency dechirping, and highlight some practical implementation issues. Discrete dechirping is shown to correspond to line integration through the extended-discrete, rather than the discrete, Wigner-Ville distribution. Computationally, dechirping is O(2N log 2N) instead of O(N-3) for direct projection, and the computation is dominated by the fast Fourier transform calculation. The noise and cross-term suppression of the Radon-Wigner transform are demonstrated by several examples using dechirping and using direct Radon-Wigner transformation. C1 UNIV MICHIGAN,DEPT PHYS MED & REHABIL,ANN ARBOR,MI 48109. NASA,LYNDON B JOHNSON SPACE CTR,ASTRONAUT OFF,HOUSTON,TX 77058. UNIV MICHIGAN,BIOENGN PROGRAM,ANN ARBOR,MI 48109. RP WOOD, JC (reprint author), YALE UNIV,NEW HAVEN,CT, USA. NR 19 TC 130 Z9 166 U1 1 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD NOV PY 1994 VL 42 IS 11 BP 3166 EP 3177 DI 10.1109/78.330375 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA PR274 UT WOS:A1994PR27400026 ER PT J AU KWACK, EY LUCHIK, TS BACK, LH AF KWACK, EY LUCHIK, TS BACK, LH TI CRYOGENIC MIXING WITH PHASE-CHANGE IN THE SIMULATION OF LO2/LH2 EXPLOSION HAZARDS - SHALLOW MIXING MODE SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article AB Experiments simulating mixing of liquid oxygen (LO2) and liquid hydrogen (LH2) have been performed to investigate the potential threat to the RTGs (Radioisotope Thermoelectric Generators) from an explosion of these cryogens as a result of a launch vehicle accident. The influence of the bottom wall of a dewar (spilled mode) has been evaluated in this investigation by using a shallow dewar (38.7 cm I.D. and 30.5 cm tall). The jet size was 1.27 cm O.D. and the jet velocity was varied from 3.97 to 8.75 m s-1. The jet dump duration times were 0.45 and 1.15 s. Gas temperatures and the boil-off of the hydrogen were measured using thermocouples and hot films. The general mixing behavior was observed with high speed measured using thermocouples and hot films. The general mixing behavior was observed with high speed video imaging. RP KWACK, EY (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 14 TC 0 Z9 0 U1 2 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 NOV PY 1994 VL 37 IS 16 BP 2535 EP 2546 DI 10.1016/0017-9310(94)90291-7 PG 12 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA PJ359 UT WOS:A1994PJ35900013 ER PT J AU CHU, PP IVANCIC, WD KIM, H AF CHU, PP IVANCIC, WD KIM, H TI ON-BOARD CLOSED-LOOP CONGESTION CONTROL FOR SATELLITE-BASED PACKET-SWITCHING NETWORKS SO INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS LA English DT Article DE PACKET SWITCHING NETWORKS; FAST PACKET SWITCH; PROPAGATION DELAY; CONGESTION CONTROL; REACTIVE CONTROL AB NASA Lewis Research Center is currently investigating a satellite architecture that incorporates an on-board packet-switching capability. Because of the statistical nature of packet switching, arrival traffic may fluctuate, and thus it is necessary to integrate the congestion control mechanism as part of the on-board processing unit. This study focuses on the closed-loop reactive control. We investigate the impact of the long propagation delay on the performance, and propose a scheme to overcome the problem. The scheme uses a global feedback signal to regulate the packet arrival rate of the ground stations. In this scheme, the satellite continuously broadcasts the status of its output buffer and the ground stations respond by selectively discarding packets or by tagging the excessive packets as low-priority. The two methods are evaluated by theoretical queueing analysis and simulation. The former is used to analyse the simplified model and to determine the basic trends and bounds, and the latter is used to assess the performance of a more realistic system and to evaluate the effectiveness of more sophisticated control schemes. The results show that the long propagation delay makes the closed-loop congestion control less responsive. The broadcast information can only be used to extract statistical information. The discarding method needs carefully-chosen status information and a reduction function, and normally requires a significant amount of ground discarding to reduce the on-board packet loss probability. The tagging method is more effective since it tolerates more uncertainties and allows a larger margin of error in status information. It can protect the high-priority packets from excessive loss and fully use the down-link bandwidth at the same time. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHU, PP (reprint author), CLEVELAND STATE UNIV,FENN COLL ENGN,DEPT ELECT ENGN,EUCLID AVE & E 24TH ST,CLEVELAND,OH 44115, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 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 NOV-DEC PY 1994 VL 12 IS 6 BP 555 EP 568 DI 10.1002/sat.4600120605 PG 14 WC Engineering, Aerospace; Telecommunications SC Engineering; Telecommunications GA QF700 UT WOS:A1994QF70000004 ER PT J AU ZAK, M AF ZAK, M TI POSTINSTABILITY MODELS IN DYNAMICS SO INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS LA English DT Article ID DETERMINISTIC REPRESENTATION; CHAOS; TURBULENCE; MECHANICS AB This paper is devoted to the concept of instability in dynamical systems with the main emphasis on orbital, Hadamard, and Reynolds instabilities. It demonstrates that the requirement about differentiability in dynamics in some cases is not consistent with the physical nature of motions, and may lead to unrealistic solutions. Special attention is paid to the fact that instability is not an invariant of motion: it depends upon frames of reference, the metric of configuration space, and classes of functions selected for mathematical models of physical phenomena. This leads to the possibility of elimination of certain types of instabilities (in particular, those which lead to chaos and turbulence) by enlarging the class of functions using the Reynolds-type transformation in combination with the stabilization principle: the additional terms (the so-called Reynolds stresses) are found from the conditions that they suppress the original instability. Based upon these ideas, a new approach to chaos and turbulence as well as a new mathematical formalism for nonlinear dynamics are discussed. RP ZAK, M (reprint author), CALTECH, JET PROP LAB, PASADENA, CA 91105 USA. NR 23 TC 13 Z9 13 U1 0 U2 0 PU SPRINGER/PLENUM PUBLISHERS PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0020-7748 EI 1572-9575 J9 INT J THEOR PHYS JI Int. J. Theor. Phys. PD NOV PY 1994 VL 33 IS 11 BP 2215 EP 2280 DI 10.1007/BF00675803 PG 66 WC Physics, Multidisciplinary SC Physics GA QB869 UT WOS:A1994QB86900008 ER PT J AU ROGERS, SE AF ROGERS, SE TI PROGRESS IN HIGH-LIFT AERODYNAMIC CALCULATIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB The current work presents progress in the effort to numerically simulate the flow over high-lift aerodynamic components, namely multielement airfoils in either a takeoff or landing configuration. The computational approach utilizes an incompressible flow solver and an overlaid chimera grid approach. A detailed grid resolution study is presented for flow over a three-element airfoil. Two turbulence models-a one-equation Baldwin-Barth model and a two-equation k-omega model-are compared. Excellent agreement with experiment is obtained for the lift coefficient at all angles of attack, including the prediction of maximum lift when using the two-equation model. Results for two other flap riggings are shown. RP ROGERS, SE (reprint author), NASA,AMES RES CTR,DIV FLUID DYNAM,COMPUTAT ALGORITHMS & APPLICAT BRANCH,M-S T27B-1,MOFFETT FIELD,CA 94035, USA. NR 0 TC 15 Z9 15 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 NOV-DEC PY 1994 VL 31 IS 6 BP 1244 EP 1251 DI 10.2514/3.46642 PG 8 WC Engineering, Aerospace SC Engineering GA PV812 UT WOS:A1994PV81200003 ER PT J AU LINTON, SW AF LINTON, SW TI COMPUTATION OF THE POSTSTALL BEHAVIOR OF A CIRCULATION CONTROLLED AIRFOIL SO JOURNAL OF AIRCRAFT LA English DT Article AB This article describes the numerical simulation of stalled and unstalled flows over a circulation controlled airfoil (CCA) using a fully implicit Navier-Stokes code, and the comparison with experimental results. Mach numbers of 0.3 and 0.5 and jet total to freestream pressure ratios of 1.4 and 1.8 are investigated. The Baldwin-Lomax and k-epsilon turbulence models are used, each modified to include the effect of strong streamline curvature. The numerical solutions of the poststall CCA shaw a highly regular unsteady periodic flowfield. This is the result of an alternation between adverse pressure gradient and shock-induced separation of the boundary layer on the airfoil trailing edge. RP LINTON, SW (reprint author), NASA,AMES RES CTR,M-S T027B-2,MOFFETT FIELD,CA 94035, USA. NR 0 TC 4 Z9 5 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1994 VL 31 IS 6 BP 1273 EP 1280 DI 10.2514/3.46647 PG 8 WC Engineering, Aerospace SC Engineering GA PV812 UT WOS:A1994PV81200008 ER PT J AU LIN, JC ROBINSON, SK MCGHEE, RJ VALAREZO, WO AF LIN, JC ROBINSON, SK MCGHEE, RJ VALAREZO, WO TI SEPARATION CONTROL ON HIGH-LIFT AIRFOILS VIA MICRO-VORTEX GENERATORS SO JOURNAL OF AIRCRAFT LA English DT Article AB An experimental investigation has been conducted to evaluate boundary-layer separation control on a two-dimensional single-flap, three-clement, high-lift system at near-flight Reynolds numbers with small surface-mounted vortex generators. The wind-tunnel testing was carried out in the NASA Langley Low-Turbulence Pressure Tunnel as part of a cooperative program between McDonnell Douglas Aerospace and NASA Langley Research Center to develop code validation data bases and to improve physical understanding of multielement airfoil flows. This article describes results obtained for small (subboundary-layer) vane-type vortex generators mounted on a multielement airfoil in a landing configuration. Measurements include lift, drag, surface pressure, wake profile, and fluctuating surface heat fluxes. The results reveal that vortex generators as small as 0.18% of reference (slat and flap stowed) wing chord (''micro-vortex generators'') can effectively reduce boundary-layer separation on the flap for landing configurations. Reduction of nap separation can significantly improve performance of the high-lift system by reducing drag and increasing lift for a given approach angle of attack. At their optimum chordwise placement on the flap, the micro-vortex generators are hidden inside the wing when the nap is retracted, thus extracting no cruise drag penalty. RP LIN, JC (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,EXPTL FLOW PHYS BRANCH,HAMPTON,VA 23681, USA. NR 0 TC 29 Z9 30 U1 1 U2 12 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 1994 VL 31 IS 6 BP 1317 EP 1323 DI 10.2514/3.46653 PG 7 WC Engineering, Aerospace SC Engineering GA PV812 UT WOS:A1994PV81200014 ER PT J AU CHADERJIAN, NM AF CHADERJIAN, NM TI NAVIER-STOKES PREDICTION OF LARGE-AMPLITUDE DELTA-WING ROLL OSCILLATIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB Vortical flow about a 65-deg sweep delta wing at Ij-deg angle of attack is numerically simulated for static roll and forced roll oscillations using the time-dependent, three-dimensional, Reynolds-averaged, Navier-Stokes (RANS) equations. This is a first step towards the development of an experimentally validated computational method for simulating wing rock with the RANS equations. Turbulent computations are presented for static roll angles up through 42 deg. The effects of roll angle on the vortex aerodynamics are discussed, and solution accuracy is evaluated by comparison with experimental data. The effects of grid refinement and zonal boundary condition treatment are assessed at zero roll angle. Computational results for a large-amplitude (Phi(max) = 40 deg), high-rate (f = 7 Hz) forced roll motion is also presented. Computed static and dynamic surface-pressure coefficients, rolling-moment coefficients, normal-force coefficients, and streamwise c.p. locations compare very well with experimental data. The static rolling-moment coefficients indicate the wing is statically stable under the present flow conditions. Moreover, the dynamic rolling-moment coefficients indicate that the fluid extracts energy from the wing motion, i.e., the wing is positively damped. The computed and experimental damping energy agree within 3%. RP CHADERJIAN, NM (reprint author), NASA,AMES RES CTR,APPL COMPUTAT FLUIDS BRANCH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 9 Z9 11 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 1994 VL 31 IS 6 BP 1333 EP 1340 DI 10.2514/3.46656 PG 8 WC Engineering, Aerospace SC Engineering GA PV812 UT WOS:A1994PV81200017 ER PT J AU BROOKS, TF BOOTH, ER BOYD, DD NIESL, GH STREBY, O AF BROOKS, TF BOOTH, ER BOYD, DD NIESL, GH STREBY, O TI ANALYSIS OF A HIGHER HARMONIC CONTROL TEST TO REDUCE BLADE-VORTEX INTERACTION NOISE SO JOURNAL OF AIRCRAFT LA English DT Article AB A noise study using an aeroelastically scaled BO-105 rotor was conducted in the German-Dutch Wind Tunnel to examine the use of higher harmonic control (HHC) of blade pitch to reduce impulsive blade-vortex interaction (BVI) noise. The noise directivity was measured over a large plane underneath the rotor using a traversing inflow microphone array. Noise and vibration measurements were made for a range of matched rotor operating conditions where prescribed (or open loop) HHC pitch, at various amplitudes and phases, was superimposed on normal (baseline) collective and cyclic trim pitch. Acoustic data are presented for 3, 4, and 5P HHC applied to a typical landing approach rotor operating condition where BVI noise is normally intense. Noise reductions of up to 6 dB were found for the advancing side BVI noise radiating upstream of the rotor, and also for the retreating side BVI noise radiating below and downstream of the rotor. The relative levels between the sides were modified by HHC control phase. To help give insight to the physics of the HHC/BVI noise problem, high-resolution loading and noise prediction results are presented for comparison to the data. The predictions are based on a new high-resolution version of the CAMRAD rotor performance program under development at Langley, called HIRES. RP BROOKS, TF (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST,HAMPTON,VA 23681, USA. NR 0 TC 15 Z9 15 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1994 VL 31 IS 6 BP 1341 EP 1349 DI 10.2514/3.46657 PG 9 WC Engineering, Aerospace SC Engineering GA PV812 UT WOS:A1994PV81200018 ER PT J AU LANSER, WR MEYN, LA AF LANSER, WR MEYN, LA TI FOREBODY FLOW-CONTROL ON A FULL-SCALE F/A-18 AIRCRAFT SO JOURNAL OF AIRCRAFT LA English DT Article AB A full-scale F/A-18 was tested in the 80- by 120-ft Wind Tunnel at NASA Ames Research Center to measure the effectiveness of pneumatic forebody vortex control devices. By altering the forebody vortex flow, yaw control can be maintained to angles of attack greater than 50 deg. Two forebody vortex control devices were tested: 1) a discrete circular jet and 2) a tangential blowing slot. The tests were conducted for angles of attack between 25-50 deg, and angles of sideslip from -15 to 15 deg. The Reynolds number based on wing mean aerodynamic chord ranged from 4.5 to 12.0 x 10(6). The time-averaged yawing moments, along with both time-averaged and time-dependent pressures on the forebodg of the aircraft, are presented here for various configurations. Of particular interest was the result that the tangentially blowing slot had a greater effect on the yawing moment than the discrete circular jet. Additionally, it was found that blowing very close to the radome apex was not as effective as blowing slightly farther aft on the radome, and that a 16-in.-long slot was more effective than either an 8- or 48-in.-long slot. RP LANSER, WR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, 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 NOV-DEC PY 1994 VL 31 IS 6 BP 1365 EP 1371 DI 10.2514/3.46660 PG 7 WC Engineering, Aerospace SC Engineering GA PV812 UT WOS:A1994PV81200021 ER PT J AU HUEBNER, LD AF HUEBNER, LD TI COMPUTATIONAL STUDY OF PLUME-INDUCED SEPARATION ON A HYPERSONIC POWERED MODEL SO JOURNAL OF AIRCRAFT LA English DT Note RP HUEBNER, LD (reprint author), NASA,LANGLEY RES CTR,DIV GAS DYNAM,HYPERSON AIRBREATHING PROPULS BRANCH,M-S 413,HAMPTON,VA 23681, USA. NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1994 VL 31 IS 6 BP 1429 EP 1431 DI 10.2514/3.46673 PG 3 WC Engineering, Aerospace SC Engineering GA PV812 UT WOS:A1994PV81200034 ER PT J AU CRANDALL, CG ENGELKE, KA CONVERTINO, VA RAVEN, PB AF CRANDALL, CG ENGELKE, KA CONVERTINO, VA RAVEN, PB TI AORTIC BAROREFLEX CONTROL OF HEART-RATE AFTER 15 DAYS OF SIMULATED MICROGRAVITY EXPOSURE SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE AORTIC BARORECEPTORS; BED REST; HEAD-DOWN TILT; SPACEFLIGHT; WEIGHTLESSNESS ID CENTRAL VENOUS-PRESSURE; CARDIAC REFLEX; BED REST; RESPONSES; HYPOTENSION; REDUCTIONS; VOLUME; MEN AB To determine the effects of simulated microgravity on aortic baroreflex control of heart rate, we exposed seven male subjects (mean age 38 +/- 3 yr) to 15 days of bed rest in the 6 degrees head-down position. The sensitivity of the aortic-cardiac baroreflex was determined during a steady-state phenylephrine-induced increase in mean arterial pressure combined with lower body negative pressure to counteract central venous pressure increases and neck pressure to offset the increased carotid sinus transmural pressure. The aortic-cardiac baroreflex gain was assessed by determining the ratio of the change in heart rate to the change in mean arterial pressure between baseline conditions and aortic baroreceptor-isolated conditions (i.e., phenylephrine + lower body negative pressure + neck pressure stage). Fifteen days of head-down tilt increased the gain of the aortic-cardiac baroreflex (from 0.45 +/- 0.07 to 0.84 +/- 0.18 beats.min(-1).mmHg(-1); P = 0.03). Reductions in blood volume and/or maximal aerobic capacity may represent the underlying mechanism(s) responsible for increased aortic baroreflex responsiveness after exposure to a ground-based analogue of microgravity. C1 UNIV N TEXAS,TEXAS COLL OSTEOPATH MED,HLTH SCI CTR,DEPT PHYSIOL,FT WORTH,TX 76107. CLIN SCI DIV,PHYSIOL RES BRANCH,BROOKS AFB,TX 78235. NASA,KENNEDY SPACE CTR,FL 32899. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 35 TC 43 Z9 44 U1 0 U2 2 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 1994 VL 77 IS 5 BP 2134 EP 2139 PG 6 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA PQ375 UT WOS:A1994PQ37500012 PM 7868425 ER PT J AU BIKLE, DD MOREYHOLTON, ER DOTY, SB CURRIER, PA TANNER, SJ HALLORAN, BP AF BIKLE, DD MOREYHOLTON, ER DOTY, SB CURRIER, PA TANNER, SJ HALLORAN, BP TI ALENDRONATE INCREASES SKELETAL MASS OF GROWING RATS DURING UNLOADING BY INHIBITING RESORPTION OF CALCIFIED CARTILAGE SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Article ID BONE LOSS; BED-REST; DICHLOROMETHYLENE DIPHOSPHONATE; SIMULATED WEIGHTLESSNESS; OSTEOCLAST NUMBER; IMMOBILIZATION; BISPHOSPHONATE; SPACEFLIGHT; HISTOMORPHOMETRY; METAPHYSIS AB Loss of bone mass during periods of skeletal unloading remains an important clinical problem. To determine the extent to which resorption contributes to the relative loss of bone during skeletal unloading of the growing rat and to explore potential means of preventing such bone loss, 0.1 mg P/kg alendronate was administered to rats before unloading of the hindquarters. Skeletal unloading markedly reduced the normal increase in tibial mass and calcium content during the 9 day period of observation, primarily by decreasing bone formation, although bone resorption was also modestly stimulated. Alendronate not only prevented the relative loss of skeletal mass during unloading but led to a dramatic increase in calcified tissue in the proximal tibia compared with the vehicle-treated unloaded or normally loaded controls. Bone formation, however, assessed both by tetracycline labeling and by [H-3]proline and Ca-45 incorporation, was suppressed by alendronate treatment and further decreased by skeletal unloading. Total osteoclast number increased in alendronate-treated animals, but values were similar to those in controls when corrected for the increased bone area. However, the osteoclasts had poorly developed brush borders and appeared not to engage the bone surface when examined at the ultrastructural level. We conclude that alendronate prevents the relative loss of mineralized tissue in growing rats subjected to skeletal unloading, but it does so primarily by inhibiting the resorption of the primary and secondary spongiosa, leading to altered bone modeling in the metaphysis. C1 UNIV CALIF SAN FRANCISCO,DEPT MED,SAN FRANCISCO,CA. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. HOSP SPECIAL SURG,ELECTRON MICROSCOPE LAB,NEW YORK,NY 10021. RP BIKLE, DD (reprint author), VET ADM MED CTR,ENDOCRINE UNIT,SAN FRANCISCO,CA 94121, USA. NR 41 TC 49 Z9 49 U1 0 U2 1 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD NOV PY 1994 VL 9 IS 11 BP 1777 EP 1787 PG 11 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA PN662 UT WOS:A1994PN66200014 PM 7863829 ER PT J AU BIKLE, DD HARRIS, J HALLORAN, BP MOREYHOLTON, ER AF BIKLE, DD HARRIS, J HALLORAN, BP MOREYHOLTON, ER TI SKELETAL UNLOADING INDUCES RESISTANCE TO INSULIN-LIKE GROWTH-FACTOR-I SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Article ID FACTOR BINDING-PROTEINS; FETAL-RAT CALVARIAE; BONE-FORMATION; SIMULATED WEIGHTLESSNESS; RECEPTOR CONCENTRATION; PARATHYROID-HORMONE; COLLAGEN-SYNTHESIS; WEIGHT-BEARING; ORGAN-CULTURE; FACTOR IGF AB In previous studies with a hindlimb elevation model, we demonstrated that skeletal unloading transiently inhibits bone formation. This effect is limited to the unloaded bones (the normally loaded humerus does not cease growing), suggesting that local factors are of prime importance. IGF-I is one such factor; it is produced in bone and stimulates bone formation. To determine the impact of skeletal unloading on IGF-I production and function, we assessed the mRNA levels of IGF-I and its receptor (IGF-IR) in the proximal tibia and distal femur of growing rats during 2 weeks of hindlimb elevation. The mRNA levels for IGF-I and IGF-IR rose during hindlimb elevation, returning toward control values during recovery. This was accompanied by a 77 % increase in IGF-I levels in the bone, peaking at day 10 of unloading, Changes in IGF binding protein levels were not observed. Infusion of IGF-I (200 mu g/day) during 1 week of hindlimb elevation doubled the increase in bone mass of the control animals but failed to reverse the cessation of bone growth in the hindlimb-elevated animals. We conclude that skeletal unloading induces resistance to IGF-I, which may result secondarily in increased local production of IGF-I. C1 UNIV CALIF SAN FRANCISCO,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BIKLE, DD (reprint author), VET ADM MED CTR,ENDOCRINE RES UNIT,4150 CLEMENT ST,SAN FRANCISCO,CA 94121, USA. NR 51 TC 57 Z9 58 U1 0 U2 1 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD NOV PY 1994 VL 9 IS 11 BP 1789 EP 1796 PG 8 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA PN662 UT WOS:A1994PN66200015 PM 7532347 ER PT J AU CHOU, MD AF CHOU, MD TI COOLNESS IN THE TROPICAL PACIFIC DURING AN EL-NINO EPISODE SO JOURNAL OF CLIMATE LA English DT Article ID OUTGOING LONGWAVE RADIATION; BUDGET EXPERIMENT; CIRRUS CLOUDS; CLIMATE; IMPACT; MODEL AB The response of radiation budgets to changes in water vapor and clouds in an El Nino episode is investigated using the analyzed sea surface temperature and satellite-derived clouds and the earth radiation budgets for the tropical Pacific (30 degrees N-30 degrees S, 100 degrees E-100 degrees W). Analyses are performed for April 1985 and April 1987. The former is a non-El Nino year and the latter is an El Nino year. Compared to April 1985, when the SST over the central and eastern equatorial Pacific is approximately 2 degrees C lower, the high-level cloudiness in April 1987 increases in the central and eastern equatorial Pacific. Corresponding to the increase in cloudiness, the outgoing longwave radiation and the net downward solar radiation at the top of the atmosphere decrease. The patterns of these changes are reversed in the western tropical Pacific and the Northern Hemispheric (NH) subsidence region centered at approximately 20 degrees N, indicating an eastward shift of the convection center from the maritime continents to the central equatorial Pacific and a strengthened NH Hadley circulation. The earth-atmosphere system in the region receives less radiative energy by 4 W m(-2) in the warmer month of April 1987 than in the month of April 1985, which is primarily caused by a reduced atmospheric clear sky greenhouse effect in the NH tropical Pacific in April 1987. Clouds have strong effects on both the IR and solar radiation, but the net effect on the radiation budget at the top of the atmosphere changes only slightly between April 1985 and April 1987. The results are consistent with Lindzen's hypothesis that reduced upper-tropospheric water vapor in the vicinity of the enhanced convection region produces cooling that counteracts warming in the Tropics. RP CHOU, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 25 TC 39 Z9 39 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD NOV PY 1994 VL 7 IS 11 BP 1684 EP 1692 DI 10.1175/1520-0442(1994)007<1684:CITTPD>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PR942 UT WOS:A1994PR94200004 ER PT J AU SOHN, BJ AF SOHN, BJ TI TEMPERATURE-MOISTURE BIASES IN ECMWF ANALYSES BASED ON CLEAR-SKY LONGWAVE SIMULATIONS CONSTRAINED BY SSMI AND MSU MEASUREMENTS AND COMPARISONS TO ERBE ESTIMATES SO JOURNAL OF CLIMATE LA English DT Article ID GENERAL-CIRCULATION MODEL; SENSOR MICROWAVE IMAGER; RANGE-WEATHER-FORECASTS; RADIATION BUDGET; PRECIPITABLE WATER; GLOBAL OCEANS; DATA SETS; SATELLITE; ALGORITHMS; CLIMATE AB Clear sky longwave radiation fluxes for the summer of 1988 and winter of 1989 have been simulated with a radiative transfer model that includes derailed treatment of atmospheric gas absorption. The input data to the model are humidity and temperature profiles from ECMWF analyses and surface temperature measurements from the International Satellite Cloud Climatology Project, To reduce the inherent uncertainties in humidity profiles, the ECMWF moisture fields have been adjusted, based on the climatological relationship between the moisture profile and total precipitable water (PW), so that the ECMWF PW is equal to that derived from Special Sensor Microwave Imager (SSMI) data. SSMI and ECMWF PW patterns are generally similar, but significant differences in magnitude are found in the low latitudes, particularly over the subtropical oceans in the Southern Hemisphere, At the same time the tropospheric brightness temperature (T-B) at 53.74 GHz has been computed using a microwave transfer model with ECMWF temperature and humidity fields as inputs. The comparison of computed T-B With the Microwave Sounding Unit (MSU) channel 2 T-B revealed differences larger than 1.5 K over most of the oceans, suggesting that the ECMWF model atmosphere has a cold bias. Maximum biases greater than 3 K are found in low latitudes. After removing the bias from the ECMWF temperature field, a new set of temperature profiles yielding brightness temperature equal to MSU channel 2 T-B has been obtained. Simulation results clearly demonstrate that inclusion of satellite estimates of PW and T-B enhances the accuracy of the clear sky LW flux simulation, substantially reducing the differences from Earth Radiation Budget Experiment (ERBE) estimates. Global averages indicate that the model-derived top-of-atmosphere (TOA) clear sky fluxes from the adjusted moisture and temperature profiles are in very good agreement with satellite-measured ERBE values, differing by only 1.4 W m(-2). By contrast, the calculation using only ECMWF analyses without any adjustments gives a significant underestimation of TOA clear sky fluxes up to 10.7 W m(-2) compared to the satellite measurements, suggesting that the constraint method can significantly improve the accuracy in the radiation budget simulation. The results also indicate that the ECMWF-based simulation errors are, at least for the two seasons studied, mainly attributed to the error in the temperature field rather than to errors in the moisture field. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,INST GLOBAL CHANGE RES & EDUC,HUNTSVILLE,AL. NR 39 TC 6 Z9 6 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD NOV PY 1994 VL 7 IS 11 BP 1707 EP 1718 DI 10.1175/1520-0442(1994)007<1707:TBIEAB>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PR942 UT WOS:A1994PR94200006 ER PT J AU POVINELLI, ML KORPELA, SA CHAIT, A AF POVINELLI, ML KORPELA, SA CHAIT, A TI SOLUTE BOUNDARY-LAYER ON A ROTATING CRYSTAL SO JOURNAL OF CRYSTAL GROWTH LA English DT Article AB A perturbation analysis has been carried out for the solutal boundary layer next to a rotating crystal. Our aim is to extend the classical results of Burton, Prim and Slichter [1] in order to obtain higher order terms in asymptotic expansions for the concentration field and boundary-layer thickness. Expressions for the effective segregation coefficient are directly obtained from the concentration solution in the two limits that correspond to weak and strong rotation. C1 MAGNIFICAT HIGH SCH,ROCKY RIVER,OH 44116. OHIO STATE UNIV,DEPT MECH ENGN,COLUMBUS,OH 43210. NASA,LEWIS RES CTR,COMPUTAT MAT LAB,CLEVELAND,OH 44135. RI Povinelli, Michelle/A-5663-2015 NR 4 TC 1 Z9 1 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 NOV PY 1994 VL 144 IS 1-2 BP 103 EP 106 DI 10.1016/0022-0248(94)90017-5 PG 4 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA PT832 UT WOS:A1994PT83200016 ER PT J AU HOFFMAN, RA FUJII, R SUGIURA, M AF HOFFMAN, RA FUJII, R SUGIURA, M TI CHARACTERISTICS OF THE FIELD-ALIGNED CURRENT SYSTEM IN THE NIGHTTIME SECTOR DURING AURORAL SUBSTORMS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID TWO-DIMENSIONAL OBSERVATIONS; 3-DIMENSIONAL CURRENT FLOW; WESTWARD TRAVELING SURGE; ELECTRIC-FIELDS; ZONE CURRENTS; MIDNIGHT SECTOR; MORNING SECTOR; MAGNETOMETER; TRIAD AB Fujii et al. (1994) obtained characteristics of the electrodynamic parameters, that is, field-aligned currents, electric fields, and electron precipitation, which are associated with amoral substorm event in the nighttime sector, through a unique-analysis that places the ionospheric measurements of these parameters into the context of a generic substorm determined from global auroral images. In this paper we investigate in considerably more detail the characteristics of the field-aligned currents using data from the same set of passes as the previous study. We show for the first time that the net upward field-aligned currents throughout the surge and surge horn are sufficient to account for most if not all of the converging currents df the amoral electrojets. Current densities are largest in the surge and surge horn. Current region continuity does not appear to exist across the substorm bulge region. Much of the amoral substorm field-aligned current is composed of filamentary currents and finite current segments at large angles to each other. The westward electrojet may contain large gradients in intensity both in local time and latitude due to sets of localized field-aligned currents. The net downward current for several hours to the west of the surge is insufficient to account for the eastward electrojet, consistent with the concept that this electrojet originates primarily on the dayside. Our pattern of field-aligned currents associated with the surge has common features and also differs significantly from the patterns previously derived from data from radars and ground-based magnetometer arrays. Our pattern is considerably more complex, probably due to the much higher resolution in latitude of the satellite data. It is also larger in area, since our average substorm is much larger than those pertaining to the previous patterns, giving a substorm wedge considerably wider than that obtained from the radar and array data. C1 NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,NAGOYA,AICHI 46401,JAPAN. TOKAI UNIV,INST RES & DEV,TOKYO 151,JAPAN. RP HOFFMAN, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. NR 42 TC 43 Z9 44 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1994 VL 99 IS A11 BP 21303 EP 21325 DI 10.1029/94JA01659 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP433 UT WOS:A1994PP43300010 ER PT J AU PESNELL, WD OMIDVAR, K HOEGY, WR WHARTON, LE AF PESNELL, WD OMIDVAR, K HOEGY, WR WHARTON, LE TI O+-O COLLISION FREQUENCY IN HIGH-SPEED FLOWS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; ATOMIC OXYGEN; LATITUDE AB Throughout much of the terrestrial thermosphere and ionosphere, the motions of the neutral and ionized constituents are closely coupled and relative velocities are small, of the order of 100 m s(-1) or less. This is particularly true at midlatitudes to low latitudes where typical velocities in the neutral gas due to tidal forcing are only 20-50 m s(-1). However, the solar wind-magnetosphere interaction drives a large-scale convection pattern in the polar ionosphere. When the rapid adjustment of the plasma to changes in the solar wind is combined with the slower response of the more massive neutral gas, large relative velocities on the order of 1 km s(-1) can exist for substantial lengths of time. This will be more common during periods of high geomagnetic activity, as a result of the greater number of magnetic substorms and other particle precipitation events. When a significant relative velocity is present, the calculation of interaction parameters of the two gases passing through each other, such as collision frequency, must include that velocity. These effects are usually neglected when interpreting wind and ion drift observations. We show how the collision frequency is affected by a directed relative velocity between any two gases interacting with a power law or exponential potential energy curves. The directed velocity increases the collision frequency at all temperatures for most ion-neutral interactions. For certain power law potentials, such as the charge quadrupole, the collision frequency is decreased. We present an analytic solution for the high-speed collision integral using the resonance charge exchange cross section. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP PESNELL, WD (reprint author), APPL RES CORP,SUITE 1120,8201 CORP DR,LANDOVER,MD 20785, USA. RI Pesnell, William/D-1062-2012 OI Pesnell, William/0000-0002-8306-2500 NR 27 TC 2 Z9 2 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1994 VL 99 IS A11 BP 21375 EP 21382 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP433 UT WOS:A1994PP43300015 ER PT J AU TORR, DG CHANG, T RICHARDS, P GERMANY, G AF TORR, DG CHANG, T RICHARDS, P GERMANY, G TI N-2 LYMAN-BIRGE-HOPFIELD DAYGLOW FROM ATLAS-1 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CROSS-SECTIONS; ULTRAVIOLET DAYGLOW; TEMPERATURE-DEPENDENCE; SOLAR MAXIMUM; EMISSIONS; RESOLUTION; PHOTOABSORPTION; SPECTROSCOPY; MOLECULES; NITROGEN AB Spectral measurements of the far ultraviolet dayglow were made from the ATLAS 1 shuttle mission using an intensified-CCD imaging spectrometer array. The instrument imaged relatively large (177 Angstrom) segments of the spectrum simultaneously and had the capability to image altitude in the second dimension of the two-dimensional focal plane detector when the entrance slit of the instrument was oriented perpendicular to the limb of the Earth. The FUV channel of the instrument used a CsTe photocathode rather than the more conventionally used and more solar blind CsI photocathode material. As a result, the spectra were also measured with good sensitivity at FUV wavelengths longer than 1500 Angstrom. In this paper, data are selected of specific interest to a study of the N-2 Lyman-Birge-Hopfield system using two shuttle attitudes: In the first the field of view was held at a fixed tangent ray height of similar to 140 km while scanning in wavelength, providing repeated FUV spectra over a range of latitudes and allowing comparison with our thermospheric airglow model. In the second observing sequence the line of sight of the instrument was scanned down through the atmosphere but covered about 75% of the full wavelength range. This sequence allows comparison of height dependence, including O-2 absorption effects, with the thermospheric model. In all cases, relatively good agreement is obtained with the model (run strictly in a predictive mode) in comparisons in which the line of sight must be integrated along a path that spans a considerable range of conditions (height, local time, latitude, solar zenith angle). In the case of the data sets examined in this study the vibrational population distributions show mixed results. In one case the distribution agrees well with a theoretical model based on direct electron impact excitation without a significant cascade contribution. A second case indicates a lower population in v' = 3 and a higher population in v' = 6 than would be expected from direct impact excitation alone. This supports previous indications that conditions resulting in the cascade mechanism may not always be operative. C1 UNIV ALABAMA,OPT AERON LAB,HUNTSVILLE,AL 35899. RP TORR, DG (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,PAYLOAD PROJECTS OFF,HUNTSVILLE,AL 35812, USA. NR 30 TC 10 Z9 10 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1994 VL 99 IS A11 BP 21397 EP 21407 DI 10.1029/94JA01844 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP433 UT WOS:A1994PP43300017 ER PT J AU CANE, HV RICHARDSON, IG VONROSENVINGE, TT WIBBERENZ, G AF CANE, HV RICHARDSON, IG VONROSENVINGE, TT WIBBERENZ, G TI COSMIC-RAY DECREASES AND SHOCK STRUCTURE - A MULTISPACECRAFT STUDY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; FORBUSH DECREASES; MAGNETIC CLOUDS; DISTURBANCES; DEPENDENCE; HELIOS AB We examine >60-MeV/amu ion data from three spacecraft (IMP 8 and Hellos 1 and 2) at the time of a number of shortterm (<20-day duration) cosmic ray 1 decreases (>1 GeV) detected by ground-based neutron monitors in the years 1976 to 1979. The multispacecraft data allow us to investigate the structure of the modulation region and in particular the relative importance, as a function of location, of the shock and shock driver (ejecta) in causing the reduction in particle densities. Although the shocks contributing to cosmic ray decreases often have particle enhancements associated with them in the >60-MeV/amu data, this is not the case for three of the events discussed in this paper where a shock-associated decrease is also evident. Whereas the shock can cause an increase or decrease at low (i.e., less than neutron monitor) energies, the reduction of particle densities in the driver, if it is intercepted, is usually evident at all energies. Thus the overall shape of a decrease at >60 MeV/amu depends primarily on whether the ejecta is intercepted. We find that the particle density inside ejecta increases with increasing radial distance from the Sun. In many of the events in this study, entry and exit of ejecta are accompanied by abrupt changes in the decrease and recovery rates which indicate that the effect of the ejecta is local. In contrast, the effect of the shock lasts many days after the shock has passed by and is evident at large angular distances from the longitude of the solar source, i.e., the effect of the shock is nonlocal. Within 1 AU there seems to be no radial dependence of the shock effect. One cosmic ray decrease seen at Earth, which had an unusual profile, can be understood if the median plane of the ejecta was inclined to the ecliptic. C1 CHRISTIAN ALBRECHTS UNIV KIEL,INST REINE & ANGEW KERNPHYS,W-2300 KIEL,GERMANY. UNIV TASMANIA,DEPT PHYS,HOBART,TAS 7001,AUSTRALIA. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. RP CANE, HV (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 29 TC 59 Z9 60 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1994 VL 99 IS A11 BP 21429 EP 21441 DI 10.1029/94JA01529 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP433 UT WOS:A1994PP43300023 ER PT J AU WHANG, YC BURLAGA, LF AF WHANG, YC BURLAGA, LF TI INTERACTION OF GLOBAL MERGED INTERACTION REGION SHOCK WITH THE HELIOPAUSE AND ITS RELATION TO THE 2-KHZ AND 3-KHZ RADIO EMISSIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND INTERACTION; TERMINATION SHOCK; OUTER HELIOSPHERE; INTERSTELLAR-MEDIUM; COSMIC-RAYS; MODEL; HYDROGEN; GAS; CONSTRAINTS; EVOLUTION AB We use Voyager 2 plasma and magnetic field data together with a one-fluid magneto-hyhrodynamics model to study the interactions of the 1991 global merged interaction region (GMIR) shock with the termination shock and the heliopause. The 1991 GMIR is an extraordinarily large global solar wind structure in radial, longitudinal, and latitudinal extents. It has a strong shock at the leading edge. After its penetration through the termination shock, the GMIR shock first propagates through the subsonic solar wind, then interacts with the heliopause. The interaction produces a transmitted shock propagating outward in the interstellar medium, and a reflected shock propagating backward in the subsonic solar wind. We identify the reflected shock and the transmitted shock as the possible source of the radio noise detected at Voyagers (Gurnett, et al., 1993). The plasma frequency behind the reflected and the transmitted shock can be responsible for the 2- and 3-kHz radio emissions, respectively. The two bands of radio noise are emitted from sources on both sides of the heliopause starting at about the same time. If the emissions picked up by Voyager are due to f(p) radiation, then the heliopause is located at R similar to 130 AU. If the emissions sue due to 2f(p) radiation, then R similar to 150 AU. Because the relative speed of the interstellar plasma with respect td the sun appears to be sub-Alfvenic, it is very unlikely there is a fast-mode bow shock of the heliosphere. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP WHANG, YC (reprint author), CATHOLIC UNIV AMER,DEPT MECH ENGN,WASHINGTON,DC 20064, USA. NR 42 TC 25 Z9 25 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 1994 VL 99 IS A11 BP 21457 EP 21465 DI 10.1029/94JA02000 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP433 UT WOS:A1994PP43300025 ER PT J AU BURLAGA, LF NESS, NF BELCHER, JW SZABO, A ISENBERG, PA LEE, MA AF BURLAGA, LF NESS, NF BELCHER, JW SZABO, A ISENBERG, PA LEE, MA TI PICKUP PROTONS AND PRESSURE-BALANCED STRUCTURES - VOYAGER-2 OBSERVATIONS IN MERGED INTERACTION REGIONS NEAR 35-AU SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERSTELLAR NEUTRAL HYDROGEN; SOLAR-WIND; SHOCK; IONS; ELECTRONS; FLUXES AB Five pressure-balanced structures, each with a scale of the order of a few hundredths of an astronomical unit (AU), were identified in two merged interaction regions (MIRs) near 35 AU in the Voyager 2 plasma and magnetic field data. They include a tangential discontinuity, simple and complex magnetic holes, slow correlated variations among the plasma and magnetic field parameters, and complex uncorrelated variations among the parameters. The changes in the magnetic pressure in these events are balanced by changes in the pressure of interstellar pickup protons. Thus the pickup protons probably play a major role in the dynamics of the MIRs. The solar wind proton and electron pressures are relatively unimportant in the MIRs at 35 AU and beyond. The region near 35 AU is a transition region: the Sun is the source of the magnetic field, but the interstellar medium is the source of pickup protons. Relative to the solar wind proton gyroradius, the thicknesses of the discontinuities and simple magnetic holes observed near 35 AU are at least an order of magnitude greater than those observed at 1 AU. However, the thicknesses of the tangential discontinuity and simple magnetic holes observed near 35 AU (in units of the pickup proton Larmor radius) are comparable to those observed at 1 AU (in units of the solar wind proton gyroradius). Thus the gyroradius of interstellar pickup protons controls the thickness of current sheets near 35 AU. We determine the interstellar pickup proton pressure in the PBSs. Using a model for the pickup proton temperature, we estimate that the average interstellar pickup proton pressure, temperature and density in the MIRs at 35 AU are (0.53 +/- 0.14) x 10(-12) erg/cm(3), (5.8 +/- 0.4) x 10(6) degrees K and (7 +/- 2) x 10(-4) cm(-3), respectively. C1 MIT, DEPT PHYS, CAMBRIDGE, MA 02139 USA. MIT, CTR SPACE RES, CAMBRIDGE, MA 02139 USA. UNIV DELAWARE, BARTOL RES INST, NEWARK, DE 19716 USA. UNIV NEW HAMPSHIRE, CTR SPACE SCI, DURHAM, NH 03824 USA. RP BURLAGA, LF (reprint author), NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. NR 45 TC 74 Z9 74 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1994 VL 99 IS A11 BP 21511 EP 21524 DI 10.1029/94JA01999 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP433 UT WOS:A1994PP43300028 ER PT J AU KARIMABADI, H KRAUSSVARBAN, D OMIDI, N FUSELIER, SA NEUGEBAUER, M AF KARIMABADI, H KRAUSSVARBAN, D OMIDI, N FUSELIER, SA NEUGEBAUER, M TI LOW-FREQUENCY INSTABILITIES AND THE RESULTING VELOCITY DISTRIBUTIONS OF PICKUP IONS AT COMET HALLEY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID WATER GROUP IONS; ELECTROMAGNETIC PLASMA-WAVES; P GRIGG-SKJELLERUP; SOLAR-WIND; COMPUTER-SIMULATIONS; GIACOBINI-ZINNER; WHISTLER WAVES; NEWBORN IONS; BOW SHOCK; GENERATION AB The interaction between the solar wind and newborn cometary ions is studied using a new analytical theory as well as one- and two-dimensional hybrid simulations. Using the observed parameters upstream of the comet Halley, a det ailed study of wave excitation and the resulting particle distributions is presented. Linear theory as well as simulations show that a variety of modes such as the fast magnetosonic mode, high frequency whistlers and obliquely propagating Alfven ion cyclotron waves can be excited. However, parallel propagating waves are found to be dominant in the wave spectrum and to control the scattering of the pickup ions. Several features of the observed distributions of pickup protons are explained. In particular, it is shown that the observed asymmetric pitch angle distribution for the pickup protons is due to the small saturation amplitude of the waves for the given parameters. Water group associated waves can lead to energy diffusion and further pitch angle scattering of protons. This effect is most likely to be important in the vicinity of the bow shock of comet Halley where the density of water group ions becomes comparable to that of protons. It is shown that the observed increase in the radius of the proton velocity shell just outside the bow shock can be due to water group waves. The nearly isotropic proton pitch angle distribution observed by Neugebauer et al. [1989] just outside the bow shock may, however, be related to the presence of a rotational discontinuity which has been identified in the magnetic field data. Just outside the bow shock, simulations show that parallel propagating water group waves can steepen with attached whistler wave packets. The steepening process at parallel propagation is a transient effect, in an important contrast to the case of steepening at oblique angles. The smaller beam densities at comet Halley appears to be the main reason not only why waves at comet Halley have smaller amplitudes but also why oblique, steepening magnetosonic waves have not been detected at comet Halley, whereas they have been seen at comet Giacobini-Zinner. C1 LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP KARIMABADI, H (reprint author), UNIV CALIF SAN DIEGO,DEPT ELECT & COMP ENGN,LA JOLLA,CA 92093, USA. NR 35 TC 11 Z9 11 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1994 VL 99 IS A11 BP 21541 EP 21556 DI 10.1029/94JA01768 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP433 UT WOS:A1994PP43300030 ER PT J AU GAWRONSKI, W MELLSTROM, JA AF GAWRONSKI, W MELLSTROM, JA TI ANTENNA SERVO DESIGN FOR TRACKING LOW-EARTH-ORBITING SATELLITES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB The upcoming NASA missions will require tracking of low-orbit satellites. As a consequence, NASA antennas will be required to track satellites at higher rates than for the current deep-space missions. This paper investigates servo design issues for the 34-m beam-waveguide antennas that track low-orbit satellites. This includes upgrading the servo with a feedforward loop, monopulse controller design, and tracking error reduction either through proper choice of elevation pinion location or through application of a notch filter or adjustment of the elevation drive amplifier gain, Finally, improvement of the signal-to-noise ratio through averaging of the oversampled monopulse signal is described. RP GAWRONSKI, W (reprint author), CALTECH,JET PROP LAB,GROUND ANTENNAS & FACILITIES ENGN SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 0 Z9 1 U1 1 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 1994 VL 17 IS 6 BP 1179 EP 1184 DI 10.2514/3.21330 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300005 ER PT J AU LEW, JS KEEL, LH JUANG, JN AF LEW, JS KEEL, LH JUANG, JN TI QUANTIFICATION OF PARAMETRIC UNCERTAINTY VIA AN INTERVAL MODEL SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID IDENTIFICATION AB The quantification of model uncertainty becomes increasingly important as robust control is an important tool for control system design and analysis. This paper presents an algorithm to characterize the model uncertainty in terms of parametric and nonparametric uncertainties directly from input/output data, We focus on the quantification of parametric uncertainty, which is represented as an interval system of the transfer function, Using this family of transfer functions (interval system), we give complete analysis of the system, A numerical example is used to demonstrate and verify the developed algorithm. The example illustrates the application of recently developed interval system techniques to the identified interval models. C1 NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23681. RP LEW, JS (reprint author), TENNESSEE STATE UNIV,CTR EXCELLENCE INFORMAT SYST,NASHVILLE,TN 37203, USA. NR 17 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1994 VL 17 IS 6 BP 1212 EP 1218 DI 10.2514/3.21335 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300010 ER PT J AU TAKAHASHI, MD AF TAKAHASHI, MD TI H-INFINITY HELICOPTER FLIGHT CONTROL LAW DESIGN WITH AND WITHOUT ROTOR STATE-FEEDBACK SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID EIGENSTRUCTURE ASSIGNMENT; H-2 AB An H-infinity formulation to design pitch-roll flight control laws for hovering helicopters is presented. Adjustment of the weight functions in the formulation is relatively straightforward. The feedback performance is set by the crossover frequency, which can be directly adjusted through the sensitivity (1 + KG)(-1) weight function. The closed-loop stability is controlled by the complementary sensitivity KG(1 + KG)(-1) weight function. The relative size of the dynamic gains is adjusted through the control (1 + KG)K--1 weight function. A framework to use the H-infinity compensation is also presented that allows systematic compliance to the quantitative low-speed requirements of a modern combat rotorcraft handling qualities specification (ADS-33C). Using this H-infinity formulation, control law designs were developed to investigate the effect of using rotor state feedback. Two laws were developed for an articulated rotor helicopter math model in low-speed flight: a compensator using rigid-body measurements and one using body plus rotor state measurements. Both laws were designed with similar crossover frequencies, stability margins, and response types. The design without rotor state feedback has the potential to pass approximately twice as much noise to the actuators near the 1/rev frequency as the design with rotor state feedback. Furthermore, the response of the controller without rotor state feedback was more sensitive to gain variations. Because of this sensitivity, the design without rotor state feedback, configured as a high-bandwidth rate response type, showed more high-frequency oscillation in roll. RP TAKAHASHI, MD (reprint author), NASA,AMES RES CTR,AEROFLIGHTDYNAM DIRECTORATE,USA AVIAT & TROOP COMMAND,MOFFETT FIELD,CA 94035, USA. NR 19 TC 15 Z9 15 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 1994 VL 17 IS 6 BP 1245 EP 1251 DI 10.2514/3.21340 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300015 ER PT J AU CHENG, VHL LAM, T AF CHENG, VHL LAM, T TI AUTOMATIC GUIDANCE AND CONTROL FOR HELICOPTER OBSTACLE AVOIDANCE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ROTORCRAFT AB The helicopter nap-of-the-earth flight problem has previously been discussed in various papers. The concept of automatic guidance involving obstacle avoidance requires a sophisticated obstacle detection system to provide three-dimensional obstacle and terrain data in flight in a hostile and unknown environment, Passive imaging sensors, augmented by selective use of low-detectability active sensors, will likely be needed to maximize covertness and safety, thus necessitating data fusion, The sensor data, limited by intervisibility constraints of the environment, suggest the use of heuristic arguments in night-path planning over conventional analytic techniques. In addition, explicit consideration of vehicle capability is essential in the autopilot design to assure safe flight in such close proximity to the ground, This paper describes the automatic obstacle avoidance guidance and control functions and the implementation of these functions and a mock obstacle detection system in a graphical simulation for evaluation. C1 STERLING SOFTWARE,PALO ALTO,CA 94303. RP CHENG, VHL (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 17 TC 4 Z9 5 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 1994 VL 17 IS 6 BP 1252 EP 1259 DI 10.2514/3.21341 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300016 ER PT J AU UDOMKESMALEE, S ALEXANDER, JW TOLIVAR, AF AF UDOMKESMALEE, S ALEXANDER, JW TOLIVAR, AF TI STOCHASTIC STAR IDENTIFICATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ATTITUDE AB An approach to star identification based on comparing observed pattern statistics with the precomputed star cataloged statistics is suggested. The identification criterion is based on evaluating a posteriori probabilities of designated star sequences obtained from observing different star fields. Numerical results based on a specific algorithm are presented. A number of references for other approaches are cited. RP UDOMKESMALEE, S (reprint author), CALTECH,JET PROP LAB,GUIDANCE & CONTROL SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 24 TC 23 Z9 28 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 1994 VL 17 IS 6 BP 1283 EP 1286 DI 10.2514/3.21345 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300020 ER PT J AU WON, CC SULLA, JL SPARKS, DW BELVIN, WK AF WON, CC SULLA, JL SPARKS, DW BELVIN, WK TI APPLICATION OF PIEZOELECTRIC DEVICES TO VIBRATION SUPPRESSION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Embedded piezoelectric devices may be ideally suited for vibration control of space structures, which lark an inertial ground. When subjected to an input voltage, an embedded piezoelectric actuator changes its dimensions, which in turn generates a pair of forces exerted on adjacent structural members. From the direct piezoelectric effect, an embedded piezoelectric transducer generates an electric charge proportional to the structural dynamic response. In this paper, the implementation, testing, and modeling of an active truss structure with piezoelectric sensors and actuators are described. Linear quadratic Gaussian, second-order, and direct-rate feedback control schemes are designed to suppress the vibrations of the active structure. Simulation and test results are presented. It is shown that special model reduction considerations are required to achieve good correlation between test and analysis. C1 NASA,LANGLEY RES CTR,GCD DIV,HAMPTON,VA 23681. NASA,LANGLEY RES CTR,SDYD DIV,HAMPTON,VA 23681. RP WON, CC (reprint author), LOCKHEED ENGN & SCI CO INC,HAMPTON,VA 23666, USA. NR 18 TC 34 Z9 39 U1 0 U2 5 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 1994 VL 17 IS 6 BP 1333 EP 1338 DI 10.2514/3.21352 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300027 ER PT J AU JACKSON, EB RIVERS, RA CHOWDHRY, RS RAGSDALE, WA GEYER, DW AF JACKSON, EB RIVERS, RA CHOWDHRY, RS RAGSDALE, WA GEYER, DW TI LAUNCH PAD ABORT OF THE HL-20 LIFTING BODY SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID PERSONNEL AB The capability of the HL-20 lifting-body spacecraft to perform an abort maneuver from the launch pad to a horizontal landing was studied. This study involved both piloted and batch simulation models of the vehicle. A point-mass model of the vehicle was used for trajectory optimization studies. The piloted simulation was performed in a fixed-base simulator. A candidate maneuver was developed and refined for the worst-case launch-pad-to-landing-site geometry using an iterative procedure of off-line maneuver analysis followed by piloted evaluations and heuristic improvements to the candidate maneuver. The resulting maneuver demonstrates the launch site abort capability of the HL-20 and dictates requirements for nominal abort motor performance. The sensitivity of the maneuver to variations in several design parameters was documented. C1 NASA,LANGLEY RES CTR,AIRCRAFT OPERAT BRANCH,HAMPTON,VA 23681. LOCKHEED ENGN & SCI CO INC,LANGLEY PROGRAM OFF,HAMPTON,VA 23666. UNISYS CORP,HAMPTON,VA 23666. RP JACKSON, EB (reprint author), NASA,LANGLEY RES CTR,AIRCRAFT GUIDANCE & CONTROLS BRANCH,HAMPTON,VA 23681, USA. NR 9 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1994 VL 17 IS 6 BP 1345 EP 1349 DI 10.2514/3.21354 PG 5 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300029 ER PT J AU GUPTA, S AF GUPTA, S TI POLYNOMIAL INTERPOLATION BETWEEN INPUT SAMPLES FOR CONTINUOUS-TIME SIMULATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note ID MATRIX C1 NASA,LANGLEY RES CTR,DIV GUIDANCE & CONTROL,SPACECRAFT CONTROLS BRANCH,HAMPTON,VA 23681. RP GUPTA, S (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. NR 7 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1994 VL 17 IS 6 BP 1369 EP 1371 DI 10.2514/3.21359 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300034 ER PT J AU MARKLEY, FL KENNEDY, KR NELSON, JD MOY, EW AF MARKLEY, FL KENNEDY, KR NELSON, JD MOY, EW TI AUTONOMOUS SPACECRAFT GYRO FAILURE-DETECTION BASED ON CONSERVATION OF ANGULAR-MOMENTUM SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note C1 LOCKHEED MISSILES & SPACE CO INC,SUNNYVALE,CA 94088. LOCKHEED TECH OPERAT CO,GREENBELT,MD 20770. RP MARKLEY, FL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GUIDANCE & CONTROL BRANCH,CODE 712,GREENBELT,MD 20771, 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 NOV-DEC PY 1994 VL 17 IS 6 BP 1385 EP 1387 DI 10.2514/3.21366 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QE663 UT WOS:A1994QE66300041 ER PT J AU FOX, DS AF FOX, DS TI OXIDATION PROTECTION OF POROUS REACTION-BONDED SILICON-NITRIDE SO JOURNAL OF MATERIALS SCIENCE LA English DT Article AB Oxidation kinetics of both as-fabricated and coated reaction-bonded silicon nitride (RBSN) were studied at 900 and 1000 degrees C with thermogravimetry. Uncoated RBSN exhibited internal oxidation and parabolic kinetics. An amorphous Si-C-O coating provided the greatest degree of protection to oxygen, with a small linear weight loss observed. Linear weight gains were measured on samples with an amorphous Si-N-C coating. Chemically vapour deposited (CVD) Si3N4 coated RBSN exhibited parabolic kinetics, and the coating cracked severely. A continuous-SiC-fibre-reinforced RBSN composite was also coated with the Si-C-O material, but no substantial oxidation protection was observed. RP FOX, DS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 13 TC 1 Z9 1 U1 0 U2 3 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD NOV 1 PY 1994 VL 29 IS 21 BP 5693 EP 5698 DI 10.1007/BF00349966 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA PR249 UT WOS:A1994PR24900026 ER PT J AU JENKINS, MG LARACURZIO, E FERBER, MK SALEM, JA AF JENKINS, MG LARACURZIO, E FERBER, MK SALEM, JA TI OBSERVATIONS OF INELASTIC DEFORMATION DURING HIGH-TEMPERATURE FATIGUE AND FAILURE OF A POLYCRYSTALLINE SILICON-NITRIDE SO JOURNAL OF NON-CRYSTALLINE SOLIDS LA English DT Article; Proceedings Paper CT 1st PAC RIM Meeting on Glass and Optical Materials/1st International Conference on Processing Materials for Properties (PMP 93) CY NOV 07-10, 1993 CL HONOLULU, HI SP AMER CERAM SOC, MINERALS MET & MAT SOC, MIN & MAT PROC INST JAPAN ID STRENGTH; BEHAVIOR AB The effects of rate-dependent inelastic deformation were observed during tensile static, dynamic, and cyclic fatigue testing of a hot-isotatically pressed, monolithic, polycrystalline silicon nitride in ambient air at temperatures of 1150, 1260 and 1370 degrees C. Constant stresses in static fatigue ranged from 50 to 300 MPa. Stress rates in dynamic fatigue ranged from 10(-4) to 101 MPa/s. Waveforms in cyclic fatigue included trapezoid, triangle and sine at a stress ratio, R, of 0.1, frequencies of 0.1 and 10 Hz, and maximum stresses ranging from 75 to 325 MPa. At 1150 degrees C, all fatigue results showed a similar slow Crack growth failure mechanism with no separate cyclic fatigue mechanism. However, at 1260 and 1370 degrees C the failure mechanism was multi-faceted. For both temperatures, the failure in static fatigue was dominated by the accumulation of diffusion-controlled creep cavities. In dynamic fatigue, the inelastic deformation exhibited by non-linear stress-strain curves supported the conclusion of failure by slow crack growth alone at high stress rates and by a mixture of slow crack growth and creep damage at low stress rates. Under cyclic loading,'enhanced' times to failure, attributed to viscous rate effects, occurred regardless of waveform or frequency. The stress rate was related to the stress at the onset to non-linearity, sigma(0), indicating a quasi-endurance limit below which cyclic fatigue had little 'enhancing' effect. Creep compliance relations indicated non-linear viscoelastic (or viscoplastic) behavior, leading to speculation on the role of this behavior in producing the 'enhanced' cyclic fatigue resistance. C1 OAK RIDGE NATL LAB, OAK RIDGE, TN 37831 USA. NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP JENKINS, MG (reprint author), UNIV WASHINGTON, DEPT MECH ENGN, SEATTLE, WA 98195 USA. NR 26 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-3093 J9 J NON-CRYST SOLIDS JI J. Non-Cryst. Solids PD NOV PY 1994 VL 177 BP 54 EP 66 DI 10.1016/0022-3093(94)90514-2 PG 13 WC Materials Science, Ceramics; Materials Science, Multidisciplinary SC Materials Science GA PV775 UT WOS:A1994PV77500007 ER PT J AU RYAN, MA WILLIAMS, RM ALLEVATO, CE VINING, CB LOWEMA, CK ROBIE, SB AF RYAN, MA WILLIAMS, RM ALLEVATO, CE VINING, CB LOWEMA, CK ROBIE, SB TI THERMOPHYSICAL PROPERTIES OF SODIUM BETA''-ALUMINA POLYCRYSTALLINE CERAMIC SO JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS LA English DT Article DE CERAMICS; X-RAY DIFFRACTION; THERMAL CONDUCTIVITY; THERMAL EXPANSION ID DIFFUSIVITY; HEAT AB The thermal diffusivity, heat capacity and thermal conductivity of solid samples of new, Li-stabilized, sodium beta''-alumina polycrystalline ceramic have been determined in the temperature range 500-1200 K. Unit cell parameters and the coefficient of thermal expansion have been determined using X-ray diffraction in the range 300-1273 K for similar solid ceramic samples which had been exposed to liquid sodium at high temperature as well as for new samples. Some differences in unit cell parameters were found between sodium exposed and unexposed samples. C1 SCINTAG INC,SUNNYVALE,CA 94086. USN,CTR AIR WARFARE,DIV WEAP,RES DEPT,CHINA LAKE,CA 93555. RP RYAN, MA (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 12 Z9 12 U1 2 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-3697 J9 J PHYS CHEM SOLIDS JI J. Phys. Chem. Solids PD NOV PY 1994 VL 55 IS 11 BP 1255 EP 1260 DI 10.1016/0022-3697(94)90207-0 PG 6 WC Chemistry, Multidisciplinary; Physics, Condensed Matter SC Chemistry; Physics GA QB349 UT WOS:A1994QB34900012 ER PT J AU CUCINOTTA, FA AF CUCINOTTA, FA TI FORWARD PRODUCTION OF PROTONS IN RELATIVISTIC C-12-NUCLEUS COLLISIONS SO JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS LA English DT Article ID HEAVY-ION COLLISIONS; HIGH-ENERGY; PARTICLE-PRODUCTION; NUCLEAR-EQUATION; SCATTERING; STATE; MODEL AB The production of protons in heavy ion collisions through the knockout mechanism (abrasion) is described using the Glauber model. The multiple knockouts from the projectile, including the inelastic collision series with the target, are considered using a closure approximation in treating energy conservation. Calculations for reactions of C-12 projectiles with several targets at energies of 1 and 2A GeV are compared to experiments. For large secondary proton momentum a strong dependence on the target mass is found and attributed to multiple scattering of the projectile knockouts. RP CUCINOTTA, FA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 26 TC 5 Z9 5 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0954-3899 J9 J PHYS G NUCL PARTIC JI J. Phys. G-Nucl. Part. Phys. PD NOV PY 1994 VL 20 IS 11 BP 1803 EP 1815 DI 10.1088/0954-3899/20/11/009 PG 13 WC Physics, Nuclear; Physics, Particles & Fields SC Physics GA PT061 UT WOS:A1994PT06100009 PM 11542262 ER PT J AU PALASZEWSKI, B POWELL, R AF PALASZEWSKI, B POWELL, R TI LAUNCH VEHICLE PERFORMANCE USING METALLIZED PROPELLANTS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Gelled metallized propellants provide options for increasing the performance of future launch vehicle chemical propulsion systems by increasing fuel density or specific impulse I-sp, or both. These increases in density and I-sp can significantly increase the payload, reduce the propulsion system liftoff weight, and allow a liquid rocket booster (LRB) to fit into the same volume as a solid rocket booster. As design examples, metallized propellant propulsion systems are considered as replacements for the solid rocket boosters and liquid sustainer stages on the current launch vehicles: both the Space Transportation System (STS) and the Titan IV. These vehicles are considered as examples to understand the real-world integration issues with future vehicles. Propulsion system mass-scaling equations and rocket engine performance predictions are used to estimate the size reductions of the high-density metallized boosters and some of the issues that must be considered before applying these fuels to future boosters are reviewed. A payload increase of 14-35% was enabled for the STS example using O-2/RP-l/Al and NTO/MMH/Al, respectively, while keeping an LRB within the dimensions of the SRB. No tank volume reduction or payload benefit was enabled with O-2/H-2/Al for the Space Shuttle Main Engine. A 11.2-11.6% payload increase for a Titan IV example was possible with NTO/MMH/Al propellants. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP PALASZEWSKI, B (reprint author), NASA,LEWIS RES CTR,DIV SPACE PROPULS TECHNOL,LAUNCH VEHICLE PROPULS BRANCH,METALLIZED PROPELLA,CLEVELAND,OH 44135, USA. NR 35 TC 20 Z9 23 U1 1 U2 3 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 1994 VL 10 IS 6 BP 828 EP 833 DI 10.2514/3.23821 PG 6 WC Engineering, Aerospace SC Engineering GA PQ872 UT WOS:A1994PQ87200009 ER PT J AU HEPP, AF LINNE, DL LANDIS, GA WADEL, MF COLVIN, JE AF HEPP, AF LINNE, DL LANDIS, GA WADEL, MF COLVIN, JE TI PRODUCTION AND USE OF METALS AND OXYGEN FOR LUNAR PROPULSION SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID POWER AB This article discusses production, power, and propulsion technologies for using oxygen and metals derived from lunar resources. The production process is described, and several of the more developed processes are discussed. Power requirements for chemical, thermal, and electrical production methods are compared. The discussion includes potential impact of ongoing pow er technology programs on lunar production requirements. This study also compares the performance potential of several possible metal fuels including aluminum, silicon, iron, and titanium. Space propulsion technology in the area of metal/oxygen rocket engines is discussed. C1 NASA,LEWIS RES CTR,DIV SPACE PROPULS TECHNOL,CLEVELAND,OH 44135. UNIV ARIZONA,TUCSON,AZ 85721. RP HEPP, AF (reprint author), NASA,LEWIS RES CTR,DIV POWER TECHNOL,MS 302-1,CLEVELAND,OH 44135, USA. NR 44 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1994 VL 10 IS 6 BP 834 EP 840 DI 10.2514/3.51397 PG 7 WC Engineering, Aerospace SC Engineering GA PQ872 UT WOS:A1994PQ87200010 ER PT J AU KORTE, JJ SINGH, DJ KUMAR, A AUSLENDER, AH AF KORTE, JJ SINGH, DJ KUMAR, A AUSLENDER, AH TI NUMERICAL STUDY OF THE PERFORMANCE OF SWEPT, CURVED COMPRESSION SURFACE SCRAMJET INLETS SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ AB A computational performance enhancement study was performed employing systematic modifications to a planar-sidewall compression scramjet inlet operating at an entrance Math number of 4 and at a dynamic pressure of 2040 psf. The variations included modifying the planar-sidewall compression angle as a function of height, utilizing sidewall curvature, and employing, simultaneously, both forward-swept and reverse-swept compression surfaces. Turbulent flowfield solutions were generated by solving the Reynolds-averaged Navier-Stokes equations to obtain inlet performance parameters such as total-pressure recovery, mass capture, and flowfield pressure distortion (the ratio of maximum static pressure to minimum static pressure generated at the inlet exit plane). Additionally, an inviscid parametric study was performed by employing solutions to the Euler equations to optimize a cubic polynomial that defined the longitudinal sidewall geometry. A final viscous flowfield solution of the optimized inviscid inlet geometry yielded inlet performance improvements; however, inlet top-wall surface boundary-layer shock wave separation interactions persisted. Hence, this numerical study demonstrated that enhanced performance is obtainable via curved-wall geometric modifications to the standard planar-sidewall inlet design, although future work should employ constraints to mitigate detrimental flow separation effects. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. LOCKHEED ENGN & SCI CO INC,HAMPTON,VA 23666. RP KORTE, JJ (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23681, USA. NR 11 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1994 VL 10 IS 6 BP 841 EP 847 DI 10.2514/3.23822 PG 7 WC Engineering, Aerospace SC Engineering GA PQ872 UT WOS:A1994PQ87200011 ER PT J AU YEH, FC HIPPENSTEELE, SA VANFOSSEN, GJ POINSATTE, PE AMERI, A AF YEH, FC HIPPENSTEELE, SA VANFOSSEN, GJ POINSATTE, PE AMERI, A TI HIGH REYNOLDS-NUMBER AND TURBULENCE EFFECTS ON TURBINE HEAT-TRANSFER SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ AB Experimental data on pressure distribution and heat transfer on a turbine airfoil were obtained over a range of Reynolds numbers from 0.75 to 7.0 x 10(6) and a range of turbulence intensities from 1.8 to about 15%. The purpose of this study was to obtain fundamental heat transfer and pressure distribution data over a wide range of high Reynolds numbers and to extend the heat transfer data base to include the range of Reynolds numbers encountered in the Space Shuttle main engine turbopump turbines. The results of this study indicated that Reynolds number and turbulence intensity have a large effect on both the transition from laminar to turbulent flow and the resulting heat transfer. For a given turbulence intensity, heat transfer for all Reynolds numbers at the leading edge can generally be correlated with the Frossling number developed for lower Reynolds numbers. For a given turbulence intensity, heat transfer for the airfoil surfaces downstream of the leading edge can be approximately correlated with a dimensionless parameter. Comparisons of the experimental results were also made with a numerical solution from a two-dimensional Navier-Stokes code. C1 UNIV KANSAS,LAWRENCE,KS 66044. RP YEH, FC (reprint author), NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,HEAT TRANSFER BRANCH,CLEVELAND,OH 44135, USA. NR 16 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1994 VL 10 IS 6 BP 868 EP 875 DI 10.2514/3.23825 PG 8 WC Engineering, Aerospace SC Engineering GA PQ872 UT WOS:A1994PQ87200015 ER PT J AU CAI, Z MUTHARASAN, R KO, FK STEINETZ, BM AF CAI, Z MUTHARASAN, R KO, FK STEINETZ, BM TI DEVELOPMENT OF HYPERSONIC ENGINE SEALS - FLOW EFFECTS OF PRELOAD AND ENGINE PRESSURES SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ AB A new type of engine seal is being developed to meet the needs of advanced hypersonic engines. A seal made of emerging high-temperature ceramic fibers braided in a sheath-core construction is selected for study based on its low leakage rates. Flexible, low-leakage, high-temperature seals are required to seal the movable engine panels of advanced ramjet-scramjet engines. To predict the leakage through these flexible, porous seal structures as a function of preload and engine pressures, new analytical flow models are required. An empirical leakage resistance/preload model is proposed to characterize the observed decrease in leakage with increasing preload. Empirically determined compression modulus and preload factor are used to correlate experimental leakage data for a wide range of seal architectures. Good agreement is observed between measured and predicted values over a range of engine pressures and seal preload. C1 NASA,LEWIS RES CTR,STRUCT DYNAM BRANCH,CLEVELAND,OH 44135. RP CAI, Z (reprint author), DREXEL UNIV,DEPT MAT ENGN,PHILADELPHIA,PA 19104, USA. RI Mutharasan, Raj/H-2676-2013 OI Mutharasan, Raj/0000-0002-3734-5438 NR 5 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1994 VL 10 IS 6 BP 884 EP 889 DI 10.2514/3.23827 PG 6 WC Engineering, Aerospace SC Engineering GA PQ872 UT WOS:A1994PQ87200017 ER PT J AU ESPANA, MD AF ESPANA, MD TI SIMPLE ESTIMATION ALGORITHM FOR PERFORMANCE-SEEKING CONTROLLERS SO JOURNAL OF PROPULSION AND POWER LA English DT Note RP ESPANA, MD (reprint author), NASA,NATL RES COUNCIL,DRYDEN FLIGHT RES CTR,PROPULS BRANCH,POB 273,MS 4840A,EDWARDS AFB,CA 93523, USA. NR 9 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 1994 VL 10 IS 6 BP 914 EP 916 DI 10.2514/3.23834 PG 3 WC Engineering, Aerospace SC Engineering GA PQ872 UT WOS:A1994PQ87200024 ER PT J AU TSAO, YMD BOYD, E WOLF, DA SPAULDING, G AF TSAO, YMD BOYD, E WOLF, DA SPAULDING, G TI FLUID-DYNAMICS WITHIN A ROTATING BIOREACTOR IN-SPACE AND EARTH ENVIRONMENTS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID CELLS; CULTURES AB We recently developed a mathematical model to characterize cell-medium interactions within a Couette-now bioreactor (concentric independent rotating vessel). Such models will be used to refine the conditions in bioreactors to achieve optimal cell growth. Numerical simulations and space-flight experiments have been conducted to test the model. Anchorage-dependent mammalian cell aggregates on the microcarrier beads in dynamic now environments were simulated by the trajectories of particles in the flowfield. The flowfield for the circulation of the culturing medium was modeled by the Navier-Stokes equations. The forces on a particle were assumed to be drag from fluid circulation, buoyancy from gravitational fields, and centrifugal forces from the rotation of the vessel. We first solved the momentum equations for the steady-state fluid now and then the equations for the motion of a particle. Results obtained from this study indicated that in unit gravity the bioreactor would simulate primary microgravity trajectories of particles and migration times. However, rotating the bioreactor under the influence of gravity produces a significant component of particle motion and associated shear stress not found in a microgravity environment. Moreover, the total force per unit of cross-sectional area on a particle in microgravity was significantly smaller than the calculated value in unit gravity. Experimental results from space flight support the numerical simulations. C1 MANKATO STATE UNIV,DEPT MATH,MANKATO,MN 56001. NASA,LYNDON B JOHNSON SPACE CTR,DIV MED SCI,HOUSTON,TX 77058. RP TSAO, YMD (reprint author), KRUG LIFE SCI,BIOTECHNOL FACIL,1290 HERCULES DR,SUITE 120,HOUSTON,TX 77058, USA. NR 16 TC 30 Z9 32 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1994 VL 31 IS 6 BP 937 EP 943 DI 10.2514/3.26541 PG 7 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800002 ER PT J AU RAULT, DFG AF RAULT, DFG TI AERODYNAMICS OF THE SHUTTLE ORBITER AT HIGH-ALTITUDES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The high-altitude, high-Knudsen-number aerodynamics of the Shuttle Orbiter are computed from low Earth orbit down to 100 km using three-dimensional direct simulation Monte Carlo and free-molecule codes. Results are compared with the latest Shuttle aerodynamic model, which is based on in-flight accelerometer measurements, and bridging-formula models. Good comparison is observed, except for the normal-force and pitching-moment coefficients. The present results were obtained for a generic Shuttle geometry configuration corresponding to a zero deflection for all control surfaces. RP RAULT, DFG (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 21 TC 17 Z9 21 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1994 VL 31 IS 6 BP 944 EP 952 DI 10.2514/3.26542 PG 9 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800003 ER PT J AU DOGRA, VK MOSS, JN PRICE, JM AF DOGRA, VK MOSS, JN PRICE, JM TI NEAR-WAKE STRUCTURE FOR A GENERIC CONFIGURATION OF AEROASSISTED SPACE TRANSFER VEHICLES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Results of a numerical study are presented for hypersonic low-density nitrogen gas flow about a 70-deg blunt cone using the direct simulation Monte Carlo method. The flow conditions simulated are attainable in existing low-density hypersonic wind tunnels; encompassing freestream Knudsen numbers of 0.03 to 0.001. Particular emphasis is given to the near-wake dow and its sensitivity to rarefaction and other parametric variations. A stable vortex forms in the near wake at and below a freestream Knudsen number of 0.01, and the size of the vortex increases with decreasing freestream Knudsen number. The base region of the now remains in thermal nonequilibrium for all cases. There is no formation of a lip separation shock or a distinct wake shock at these rarefied conditions. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP DOGRA, VK (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. NR 17 TC 7 Z9 7 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1994 VL 31 IS 6 BP 953 EP 959 DI 10.2514/3.26543 PG 7 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800004 ER PT J AU DAGUM, L ZHU, SK AF DAGUM, L ZHU, SK TI DIRECT SIMULATION MONTE-CARLO SIMULATION OF THE INTERACTION BETWEEN RAREFIED FREE JETS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This paper presents a direct simulation Monte Carlo (DSMC) calculation of two interacting free jets exhausting into vacuum. The computed flow field is compared against available experimental data and shows excellent agreement everywhere except in the very near field (less than one orifice diameter downstream of the jet exhaust plane). The lack of agreement in this region is attributed to having assumed an inviscid boundary condition for the orifice lip. The results serve both to validate the DSMC code for a very complex, three-dimensional, nonequilibrium flowfield, and to provide some insight into the complicated nature of this flow. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. ROCKWELL INT CORP,ROCKETDYNE DIV,CANOGA PK,CA 91303. NR 15 TC 4 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 NOV-DEC PY 1994 VL 31 IS 6 BP 960 EP 964 DI 10.2514/3.26544 PG 5 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800005 ER PT J AU WILMOTH, RG MITCHELTREE, RA MOSS, JN DOGRA, VK AF WILMOTH, RG MITCHELTREE, RA MOSS, JN DOGRA, VK TI ZONALLY DECOUPLED DIRECT SIMULATION MONTE-CARLO SOLUTIONS OF HYPERSONIC BLUNT-BODY WAKE FLOWS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Direct simulation Monte Carlo (DSMC) solutions are presented for the hypersonic now behind a blunt body in which the wake region is solved in a zonally decoupled manner. The forebody now is solved separately using either a DSMC or a Navier-Stokes method, and the forebody exit-plane solution is specified as the inflow condition to the decoupled DSMC solution of the wake region. Results are presented for a 70-deg, blunted cone at now conditions that can be accommodated in existing low-density wind tunnels with the Knudsen number (based on the base diameter) ranging from 0.03 to 0.001. The zonally decoupled solutions show good agreement with fully coupled DSMC solutions of the wake flow densities and velocities. The wake closure predicted by the zonally decoupled solutions is in better agreement with fully coupled results than that predicted by a fully coupled Navier-Stokes method, indicating the need to account for rarefaction in the wake for the cases considered. The combined use of Navier-Stokes for the forebody with a decoupled DSMC solution for the wake provides an efficient method for solving transitional blunt-body flows where the forebody now is continuum and the wake is rarefied. C1 VIGYAN INC,HAMPTON,VA 23666. RP WILMOTH, RG (reprint author), NASA,LANGLEY RES CTR,DIV GAS DYNAM,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 11 TC 9 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1994 VL 31 IS 6 BP 971 EP 979 DI 10.2514/3.26546 PG 9 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800007 ER PT J AU HAAS, BL SCHMITT, DA AF HAAS, BL SCHMITT, DA TI SIMULATED RAREFIED AERODYNAMICS OF THE MAGELLAN SPACECRAFT DURING AEROBRAKING SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID COLLISION AB Aerodynamic loads upon the Magellan spacecraft during aerobraking through the atmosphere of Venus are computed at off-design attitudes with a direct simulation Monte Carlo (DSMC) particle method. This method is not restricted to the assumption of collisionless flow normally employed to assess spacecraft aerodynamics. Simulated rarefied flows at nominal altitudes near 140 km and an entry speed of 8.6 km/s were compared with simulated and analytic free-molecular results. Aerodynamic moments, forces, and heating for rarefied entry at all attitudes were 7-10% below free-molecular results. All moments acted to restore the vehicle to its nominal zero-pitch, zero-yaw attitude. Suggested canting of the solar panels is an innovative configuration to assess gas-surface interaction during aerobraking. The resulting roll torques about the central body axis, as predicted in rarefied-now simulations, were nearly twice that predicted For free-molecular flow, although differences became less distinct for thermal accommodation coefficients well below unity. In general, roll torques increased dramatically with reduced accommodation coefficients employed in the simulation. In the DSMC code, periodic free-molecule boundary conditions and a coarse computational grid and body resolution served to minimize the simulation size and cost while retaining solution validity. C1 MARTIN MARIETTA ASTRONAUT CO,DENVER,CO 80233. RP HAAS, BL (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 230-2,MOFFETT FIELD,CA 94035, USA. NR 16 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 1994 VL 31 IS 6 BP 980 EP 985 DI 10.2514/3.26547 PG 6 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800008 ER PT J AU GREENDYKE, RB HARTUNG, LC AF GREENDYKE, RB HARTUNG, LC TI CONVECTIVE AND RADIATIVE HEAT-TRANSFER ANALYSIS FOR THE FIRE-II FOREBODY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SCHEMES AB A Navier-Stokes flowfield solution method using finite-rate chemistry and two-temperature thermal nonequilibrium was used in combination with two nonequilibrium radiative heat transfer codes to calculate heating for the FIRE II vehicle. An axisymmetric model of the actual body shape was used. One radiative heating code was used in uncoupled fashion with the flowfield solver's energy equations, while the other code was used in both coupled and uncoupled variations. Several trajectory points ranging from highly nonequilibrium now to near-equilibrium now were used for a study of both convective and radiative heating over the vehicle. Considerable variation in radiative heating was seen at the extremes, while agreement was good in the intermediate trajectory points. Total heat transfer calculations gave good comparison until the peak heating trajectory points were encountered and returned to good agreement for the last two equilibrium points. C1 NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681. RP GREENDYKE, RB (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. NR 25 TC 11 Z9 11 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 1994 VL 31 IS 6 BP 986 EP 992 DI 10.2514/3.26548 PG 7 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800009 ER PT J AU TRAN, HK RASKY, DJ ESFAHANI, L AF TRAN, HK RASKY, DJ ESFAHANI, L TI THERMAL RESPONSE AND ABLATION CHARACTERISTICS OF LIGHTWEIGHT CERAMIC ABLATORS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This paper presents the thermal performance and ablation characteristics of the newly developed lightweight ceramic ablators (LCAs) in a supersonic, high-enthalpy convective environment. Lightweight ceramic ablators were recently conceived and developed at NASA Ames using low-density ceramic or carbon fibrous matrices as substrates for main structural support and organic resins as fillers. These LCAs were successfully produced with densities ranging from approximate to 0.224 to 1.282 g/cm(3). Several infiltrants with different char yields were used to study the effect on surface recession. Tests were conducted in the NASA Ames arc-jet facilities. Material thermal performance tvas evaluated at cold-wall heat fluxes from 113.5 to 1634 W/cm(2), and stagnation pressures of 0.018 to 0.331 atm. Conventional ablators such as SLA-561, Avcoat 5026-39HC, MA-25S, and balsa wood were tested at the same heat fluxes for direct comparison. Surface temperature was measured using optical pyrometers, and the recession rates mere obtained from the high-speed films. In-depth temperature data were obtained to determine the thermal penetration depths and conductivity. Preliminary results indicated that most LCAs performed comparably to or better than conventional ablators. At low flux levels (<454 W/cm(2)), the addition of silicon carbide and polymethyl methacrylate significantly improved the ablation performance of silica substrates. The carbon-based LCAs were the most mass-efficient at high flux levels (>454 W/cm(2)). C1 SAN JOSE STATE UNIV,SAN JOSE,CA 95129. RP TRAN, HK (reprint author), NASA,AMES RES CTR,THERMAL PROTECT MAT BRANCH,MOFFETT FIELD,CA 94035, USA. NR 16 TC 15 Z9 17 U1 3 U2 18 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 1994 VL 31 IS 6 BP 993 EP 998 DI 10.2514/3.26549 PG 6 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800010 ER PT J AU RYAN, RS TOWNSEND, JS AF RYAN, RS TOWNSEND, JS TI APPLICATION OF PROBABILISTIC ANALYSIS AND DESIGN METHODS IN-SPACE PROGRAMS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The use of probabilistic analysis and design methods in space programs is steadily gaining acceptance within the aerospace community. To further enhance the development and application of probabilistic methods, four actions are recommended: 1) the development of theories, codes, and tools to match the task areas; 2) an understanding of prior applications/uses of probability and statistics, and databases; 3) the development of databases, in particular structural failures; and 4) education of engineers and managers on the merits and basics of probability/reliability methods. The approaches, the status, and the needs for these actions are examined in terms of the current limitations of probabilistic engineering methods, a basic approach for its application, a discussion of some specific uses, and recommendations of critical development areas. RP RYAN, RS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,STRUCT & DYNAM LAB,HUNTSVILLE,AL 35812, USA. NR 38 TC 2 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 1994 VL 31 IS 6 BP 1038 EP 1043 DI 10.2514/3.26555 PG 6 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800016 ER PT J AU VERDERAIME, V AF VERDERAIME, V TI FIRST-ORDER RELIABILITY APPLICATION AND VERIFICATION METHODS FOR SEMISTATIC STRUCTURES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Escalating risks of aerostructures stimulated by increasing size, complexity, and cost should no longer be ignored in conventional deterministic safety design methods. The deterministic pass-fail concept is incompatible with probability and risk assessments; stress audits are shown to be arbitrary and incomplete, and the concept compromises the performance of high-strength materials. A reliability method is proposed that combines first-order reliability principles with deterministic design variables and conventional test techniques to surmount current deterministic stress design and audit deficiencies. Accumulative and propagation design uncertainty errors are defined and appropriately implemented into the classical safety-index expression. The application is reduced to solving for a design factor that satisfies the specified reliability and compensates for uncertainty errors, and then using this design factor as, and instead of, the conventional safety factor in stress analyses. The resulting method is consistent with current analytical skills and verification practices, the culture of most designers, and the development of semistatic structural designs. RP VERDERAIME, V (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 6 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 NOV-DEC PY 1994 VL 31 IS 6 BP 1050 EP 1053 DI 10.2514/3.26557 PG 4 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800018 ER PT J AU LIN, EI AF LIN, EI TI TOPEX MICROWAVE RADIOMETER THERMAL CONTROL - POST-SYSTEM TEST MODIFICATIONS AND ON-ORBIT PERFORMANCE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The TOPEX spacecraft thermal vacuum test revealed that its Microwave Radiometer instrument thermal design neglected a shading condition, causing the model prediction of a key electronics temperature to be 7.5 degrees C higher than the test result. The thermal model and hardware were modified right before launch to correct for the design inadequacy. This paper reports on how the initially obscure problem was discovered, and how the thermal models were revised, validated, and utilized to investigate the solution options and guide the hardware modification decisions. Details related to test data interpretation, analytical uncertainties, and model-prediction vs. test-data correlation are documented. Instrument/spacecraft interface issues, where the problem originated and where in general pitfalls abound, are dealt with specifically. Finally, on-orbit thermal performance data are presented, which exhibit good agreement with flight predictions, and which indicate comfortable temperature margins. Namely, the key electronics temperature is 10 degrees C below the maximum flight allowable during the hot operating mode, and 5 degrees C above the minimum flight allowable during the cold operating mode. Lessons learned on the way to attaining this excellent thermal performance are discussed. RP LIN, EI (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1994 VL 31 IS 6 BP 1061 EP 1066 DI 10.2514/3.26559 PG 6 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800020 ER PT J AU KATZ, I BARFIELD, JN BURCH, JL MARSHALL, JA GIBSON, WC NEUBERT, T ROBERTS, WT TAYLOR, WWL BEATTIE, JR AF KATZ, I BARFIELD, JN BURCH, JL MARSHALL, JA GIBSON, WC NEUBERT, T ROBERTS, WT TAYLOR, WWL BEATTIE, JR TI INTERACTIONS BETWEEN THE SPACE EXPERIMENTS WITH PARTICLE ACCELERATORS PLASMA CONTACTOR AND THE IONOSPHERE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Space experiments with particle accelerators (SEPAC) on Atlas-1 space transportation system (STS-45) included a plasma contactor to neutralize charge buildup on the orbiter due to electron accelerator operations. The SEPAC plasma contactor operated the same as it had during testing in the laboratory. During SEPAC electron accelerator operations, the contactor emitted currents that helped balance the electron beam current. The Langmuir probe measured the charge exchange ions and the thermal electrons emitted by the contactor. The electric field wave data showed an order of magnitude increase in the 4-8 MHz band. There were no reports of contactor operations interfering with either orbiter systems or other Atlas-1 experiments. C1 SW RES INST,DEPT SPACE SYST,DIV INSTRUMENTAT & SPACE RES,SAN ANTONIO,TX 78284. UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,PAYLOAD & ORBITAL SYST OFF,HUNTSVILLE,AL 35812. NICHOLS RES CORP,NASA PROGRAMS,SPACE SCI,ARLINGTON,VA 22209. HUGHES RES LABS,DEPT PLASMA SOURCES,MALIBU,CA 90265. RP KATZ, I (reprint author), MAXWELL LABS INC,DIV S CUBED,SPACE SYST SECTOR,3398 CARMEL MT RD,SAN DIEGO,CA 92121, USA. NR 26 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 1994 VL 31 IS 6 BP 1079 EP 1084 DI 10.2514/3.26562 PG 6 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800023 ER PT J AU LUZ, PL AF LUZ, PL TI STRUCTURAL DESIGN AND MITIGATION OF MIRROR DEFORMATIONS IN LUNAR-BASED TELESCOPES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Structural design and analysis of the optical systems for lunar-based telescopes is a challenging task. A driving concern of the Lunar Ultraviolet Telescope Experiment (LUTE) preliminary design study was the degradation of the LUTE optical figure due to thermal deformations, during a temperature cycle of 65 to 265 K at the reference 40 deg latitude, 0 deg longitude landing site. In addressing this task, temperature effects mere characterized, and primary-mirror thermal deformations calculated for use in the optical analyses. Trade studies evaluated the qualitative performance of various design schemes. Results indicated that statically determinate mirror supports with bottom-mounted flexures created less optical disturbance under thermal loading than mirror supports at the inner or outer periphery. Another trade indicated that a telescope's baseplate must be athermalized with respect to the mirrors by matching thermal distortion coefficients. A comparison of three materials for the primary mirror predicted that silicon carbide would be the best material for resisting thermally induced figure deformations on the moon. RP LUZ, PL (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 14 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1994 VL 31 IS 6 BP 1092 EP 1098 DI 10.2514/3.26564 PG 7 WC Engineering, Aerospace SC Engineering GA QD728 UT WOS:A1994QD72800025 ER PT J AU FRICK, J NIELSEN, SS MITCHELL, CA AF FRICK, J NIELSEN, SS MITCHELL, CA TI YIELD AND SEED OIL CONTENT RESPONSE OF DWARF, RAPID-CYCLING BRASSICA TO NITROGEN TREATMENTS, PLANTING DENSITY, AND CARBON-DIOXIDE ENRICHMENT SO JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE LA English DT Article DE BRASSICA NAPUS; BIOREGENERATIVE LIFE SUPPORT; CELSS; CONTROLLED-ENVIRONMENT AGRICULTURE; HYDROPONICS; NASA ID OILSEED RAPE; NAPUS; GROWTH; AUTUMN; SIZE AB Effects of N level (15 to 30 mM), time of N increase (14 to 28 days after planting), and planting density (1163 to 2093 plants/m(2)) were determined for crop yield responses of dwarf, rapid-cycling brassica (Brassica napus L., CrGC 5-2, Genome: ACaacc). Crops were grown in solid-matrix hydroponic systems and under controlled-environment conditions, including nonsupplemented (ambient) or elevated CO2 concentrations (998 +/- 12 mumol mol(-1)). The highest seed yield rate obtained (4.4 g.m(-2).day(-1)) occurred with the lowest N level (15 mM) applied at the latest treatment time (day 28). In all trials, CO2 enrichment reduced seed yield rate and harvest index by delaying the onset of flowering and senescence and stimulating vegetative shoot growth. The highest shoot biomass accumulation rate (55.5 g.m-2.day(-1)) occurred with the highest N level (30 mM) applied at the earliest time (day 14). Seed oil content was not significantly affected by CO2 enrichment. Maximum seed oil content (30% to 34%, dry weight basis) was obtained using the lowest N level (15 mM) initiated at the latest treatment time (day 28). In general, an increase in seed oil content was accompanied by a decrease in seed protein. Seed carbohydrate, moisture, and ash contents did not vary significantly in response to experimental treatments. Effects of N level and time of N increase were consistently significant for most crop responses. Planting density was significant only under elevated CO2 conditions. C1 PURDUE UNIV,NASA,SPECIALIZED CTR RES & TRAINING BIOREGENERAT LIFE,DEPT HORT,W LAFAYETTE,IN 47907. PURDUE UNIV,NASA,SPECIALIZED CTR RES & TRAINING BIOREGENERAT LIFE,DEPT FOOD SCI,W LAFAYETTE,IN 47907. NR 29 TC 24 Z9 26 U1 0 U2 6 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 701 NORTH SAINT ASAPH STREET, ALEXANDRIA, VA 22314-1998 SN 0003-1062 J9 J AM SOC HORTIC SCI JI J. Am. Soc. Hortic. Sci. PD NOV PY 1994 VL 119 IS 6 BP 1137 EP 1143 PG 7 WC Horticulture SC Agriculture GA PQ015 UT WOS:A1994PQ01500005 PM 11540952 ER PT J AU DEMEO, RC WANG, TK CHOW, TP BROWN, DM MATUS, LG AF DEMEO, RC WANG, TK CHOW, TP BROWN, DM MATUS, LG TI THERMAL-OXIDATION OF SIC IN N2O SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Letter ID SILICON-CARBIDE; SIO2-FILMS AB Thermal oxidation kinetics of 3C and 6H-SiC in N2O at 1050 to 1150-degrees-C have been studied. The oxidation rate follows an unusual parabolic-linear relationship that has also been found for oxidation of silicon in N2O. The activation energy of the parabolic rate constant (B) is 3.1 +/- 0.22 eV/molecule for 3C-SiC, and 4.80 +/- 1.02 eV/molecule for 6H-SiC. The limiting mechanism for oxidation is attributed to the diffusion of CO through the oxynitride layer. 3C-SiC metal oxide semiconductor capacitors fabricated in N2O exhibit fixed oxide charge densities on the order of 10(12) cm-2 and are slightly lower than those oxidized in steam. C1 GE CO,RES & DEV,SCHENECTADY,NY 12301. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP DEMEO, RC (reprint author), RENSSELAER POLYTECH INST,CTR INTEGRATED ELECTR,TROY,NY 12180, USA. NR 13 TC 7 Z9 7 U1 0 U2 2 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 1994 VL 141 IS 11 BP L150 EP L152 DI 10.1149/1.2059325 PG 3 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA PQ524 UT WOS:A1994PQ52400004 ER PT J AU MULLER, RE MARTIN, SC SMITH, RP ALLEN, SA REDDY, M BHATTACHARYA, U RODWELL, MJW AF MULLER, RE MARTIN, SC SMITH, RP ALLEN, SA REDDY, M BHATTACHARYA, U RODWELL, MJW TI ELECTRON-BEAM LITHOGRAPHY FOR THE FABRICATION OF AIR-BRIDGED, SUBMICRON SCHOTTKY COLLECTORS SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article; Proceedings Paper CT 38th International Symposium on Electron, Ion and Photon Beams CY MAY 31-JUN 03, 1994 CL NEW ORLEANS, LA SP AMER VACUUM SOC, IEEE, ELECTRON DEVICE SOC, OPT SOC AMER ID RESONANT-TUNNELING DIODES; OSCILLATIONS; GHZ C1 UNIV CALIF SANTA BARBARA,DEPT ELECT & COMP ENGN,SANTA BARBARA,CA 93106. RP MULLER, RE (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 11 TC 7 Z9 7 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-211X J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD NOV-DEC PY 1994 VL 12 IS 6 BP 3668 EP 3672 DI 10.1116/1.587636 PG 5 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA PY133 UT WOS:A1994PY13300114 ER PT J AU TIBERIO, RC CHAPMAN, PF MARTIN, RD FOROUHAR, S LANG, RJ AF TIBERIO, RC CHAPMAN, PF MARTIN, RD FOROUHAR, S LANG, RJ TI LATERALLY COUPLED DISTRIBUTED-FEEDBACK LASER FABRICATED WITH ELECTRON-BEAM LITHOGRAPHY AND CHEMICALLY ASSISTED ION-BEAM ETCHING SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article; Proceedings Paper CT 38th International Symposium on Electron, Ion and Photon Beams CY MAY 31-JUN 03, 1994 CL NEW ORLEANS, LA SP AMER VACUUM SOC, IEEE, ELECTRON DEVICE SOC, OPT SOC AMER C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP TIBERIO, RC (reprint author), CORNELL UNIV,NATL NANOFABRICAT FACIL,ITHACA,NY 14853, USA. NR 12 TC 10 Z9 10 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-211X J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD NOV-DEC PY 1994 VL 12 IS 6 BP 3746 EP 3749 DI 10.1116/1.587435 PG 4 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA PY133 UT WOS:A1994PY13300131 ER PT J AU MALEK, CK JACKSON, K BRENNEN, RA HECHT, MH BONIVERT, WD HRUBY, J AF MALEK, CK JACKSON, K BRENNEN, RA HECHT, MH BONIVERT, WD HRUBY, J TI DEEP-ETCH X-RAY-LITHOGRAPHY AT THE ADVANCED LIGHT-SOURCE - FIRST RESULTS SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article; Proceedings Paper CT 38th International Symposium on Electron, Ion and Photon Beams CY MAY 31-JUN 03, 1994 CL NEW ORLEANS, LA SP AMER VACUUM SOC, IEEE, ELECTRON DEVICE SOC, OPT SOC AMER C1 CALTECH,JET PROP LAB,CTR SPACE MICROELECTR,PASADENA,CA 91109. SANDIA NATL LABS,DEPT MAT SYNTH,LIVERMORE,CA 94551. RP MALEK, CK (reprint author), UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,CTR XRAY OPT,BERKELEY,CA 94720, USA. NR 8 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 0734-211X J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD NOV-DEC PY 1994 VL 12 IS 6 BP 4009 EP 4012 DI 10.1116/1.587420 PG 4 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA PY133 UT WOS:A1994PY13300179 ER PT J AU ABRAMS, MJ SIEBE, C AF ABRAMS, MJ SIEBE, C TI CERRO-XALAPAXCO - AN UNUSUAL TUFF CONE WITH MULTIPLE EXPLOSION CRATERS, IN CENTRAL MEXICO (PUEBLA) SO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH LA English DT Article ID DEPOSITS; VOLCANOES; BASIN; MAARS AB The Xalapaxco tuff cone is located on the northeast flank of La Malinche stratovolcano in central Mexico. An unusually large number (10) of explosion craters, concentrated on the central and on the uphill side of the cone, expose alternating beds of stratified surge deposits and massive fall deposits. The morphology of the cone and the characteristics of its deposits point to the involvement of significant quantities of groundwater during its eruption. The phreatomagmatic eruptions which led to the cone's formation pierced an alluvial fan, whose source is a glacially carved canyon near the summit of La Malinche volcano. The large canyon was cut during repeated glacial episodes, the last of which ended ca. 8500 years ago. The present alluvial fan mostly consists of reworked glacio-fluviatile andesite/dacite material from La Malinche. Rising magma encountered substantial amounts of groundwater within the limestone basement and in overlying intercalated pyroclastic and glacio-fluviatile deposits of the alluvial fan. Short-lived phreatomagmatic eruptions produced surge and airfall deposits. Xenoliths found in the cone beds are composed of dacite and andesite clasts, limestone, chert, and rare ignimbrite fragments. No juvenile material could be unequivocally identified, but is represented most probably by porphyritic dacite similar in texture and composition to La Malinche lavas. The multiple craters were formed as a response to changes in water and magma supply during the short-lived eruption. Hence, the locations where ideal magma/water ratios existed to fuel phreatomagmatic explosions shifted in time and space. Analysis of diameter/depth ratios of the craters indicates that the activity shifted from the center of the cone to its periphery in the west. Due to the configuration of the hydrographic environment, more groundwater flowing from La Malinche was available from the fan on the uphill side than below the cone at later stages of the eruption. The apparently anomalous position of the tuff cone on the slopes of a stratovolcano in a presently dry environment can be explained by more humid climatic conditions prevailing at the time of eruption. C1 NATL AUTONOMOUS UNIV MEXICO,INST GEOFIS,MEXICO CITY 04510,DF,MEXICO. RP ABRAMS, MJ (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. OI Siebe, Claus/0000-0002-3959-9028 NR 36 TC 19 Z9 19 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0273 J9 J VOLCANOL GEOTH RES JI J. Volcanol. Geotherm. Res. PD NOV PY 1994 VL 63 IS 3-4 BP 183 EP 199 DI 10.1016/0377-0273(94)90073-6 PG 17 WC Geosciences, Multidisciplinary SC Geology GA PY144 UT WOS:A1994PY14400005 ER PT J AU BLUTH, GJS CASADEVALL, TJ SCHNETZLER, CC DOIRON, SD WALTER, LS KRUEGER, AJ BADRUDDIN, M AF BLUTH, GJS CASADEVALL, TJ SCHNETZLER, CC DOIRON, SD WALTER, LS KRUEGER, AJ BADRUDDIN, M TI EVALUATION OF SULFUR-DIOXIDE EMISSIONS FROM EXPLOSIVE VOLCANISM - THE 1982-1983 ERUPTIONS OF GALUNGGUNG, JAVA, INDONESIA SO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH LA English DT Article ID MOUNT-PINATUBO; CLOUDS; JUNE AB Galunggung volcano, Java, awoke from a 63-year quiescence in April 1982, and erupted sporadically through January 1983. During its most violent period from April to October, the Cikasasah Volcano Observatory reported 32 large and 56 moderate to small eruptions. From April 5 through September 19 the Total Ozone Mapping Spectrometer (TOMS), carried on NASA's Nimbus-7 satellite, detected and measured 24 different sulfur dioxide clouds; an estimated 1730 kilotons (kt) of SO2 were outgassed by these explosive eruptions. The trajectories, and rapid dispersion rates, of the SO2 clouds were consistent with injection altitudes below the tropopause. An additional 300 kt of SO2 were estimated to have come from 64 smaller explosive eruptions, based on the detection limit of the TOMS instrument. For the first time, an extended period of volcanic activity was monitored by remote sensing techniques which enabled observations of both the entire SO2 clouds produced by large explosive eruptions (using TOMS), and the relatively lower levels of SO2 emissions during non-explosive outgassing (using the Correlation Spectrometer, or COSPEC). Based on COSPEC measurements from August 1982 to January 1983, and on the relationship between explosive and non-explosive degassing, approximately 400 kt of SO2 were emitted during non-explosive activity. The total sulfur dioxide outgassed from Galunggung volcano from April 1982 to January 1983 is calculated to be 2500 kt (+/- 30%) from both explosive and non-explosive activity. While Galunggung added large quantities of sulfur dioxide to the atmosphere, its sporadic emissions occurred in relatively small events distributed over several months, and reached relatively low altitudes, and are unlikely to have significantly affected aerosol loading of the stratosphere in 1982 by volcanic activity. C1 UNIV MARYLAND,DEPT GEOL,COLLEGE PK,MD 20742. US GEOL SURVEY,DENVER,CO 80225. UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD 20742. HUGHES STX CORP,LANHAM,MD. NASA,GODDARD SPACE FLIGHT CTR,EARTH SCI DIRECTORATE,GREENBELT,MD 20771. DIREKTORAT VULKANOLOGI,DEPT PERTAMBANGAN DAN ENERGI,BANDUNG,INDONESIA. NR 21 TC 33 Z9 33 U1 0 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0273 J9 J VOLCANOL GEOTH RES JI J. Volcanol. Geotherm. Res. PD NOV PY 1994 VL 63 IS 3-4 BP 243 EP 256 DI 10.1016/0377-0273(94)90077-9 PG 14 WC Geosciences, Multidisciplinary SC Geology GA PY144 UT WOS:A1994PY14400009 ER PT J AU MAEKAWA, H MANSOUR, NN AF MAEKAWA, H MANSOUR, NN TI CONTROL OF STRUCTURES AND TIME-AVERAGED FLOW PROPERTIES OF A PLANE WAKE BY SUBHARMONIC INSTABILITY MODES SO JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING LA English DT Article DE COMPUTATIONAL FLUID DYNAMICS; WAKE; TRANSITION; SPECTRAL METHOD TURBULENCE CONTROL; INSTABILITY MODE; SUBHARMONICS ID 2-DIMENSIONAL WAKE; MIXING LAYERS; STABILITY AB In the present work, structures and time-averaged flow properties in the transition region of a plane wake perturbed by the unstable subharmonic modes were studied by means of direct numerical simulations. The incompressible time-dependent 2-D 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 (fundamental mode and its subharmonics) of the Orr-Sommerfeld equations were used to perturb a Gaussian wake of the inlet plane. The statistics of the wake forced by the unstable modes and the corresponding numerical structures of the vortices are presented. When the wake is forced by the fundamental mode and its two subharmonics with large amplitudes, the dominant evolution of the fundamental mode is responsible for the clear alternating sign Vortices and the downstream statistics. After the fundamental mode saturates, the subharmonic components grow downstream. Further downstream, the influence of the first subharmonics on the Vortex street and the turbulent statistics are observed. The downstream evolutions of Reynolds stresses are governed by the growth of the subharmonics. The cross-stream profiles of the Reynolds stresses are asymmetric because of the spatial evolution of the first subharmonics. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP MAEKAWA, H (reprint author), UNIV ELECTROCOMMUN,DEPT MECH & CONTROL ENGN,CHOFU,TOKYO 182,JAPAN. NR 14 TC 1 Z9 1 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 B-FLUID T JI JSME Int. J. Ser. B-Fluids Therm. Eng. PD NOV PY 1994 VL 37 IS 4 BP 806 EP 814 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PZ519 UT WOS:A1994PZ51900022 ER PT J AU MASUKO, M JONES, WR JANSEN, R EBIHARA, B PEPPER, SV HELMICK, LS AF MASUKO, M JONES, WR JANSEN, R EBIHARA, B PEPPER, SV HELMICK, LS TI A VACUUM 4-BALL TRIBOMETER TO EVALUATE LIQUID LUBRICANTS FOR SPACE APPLICATIONS SO LUBRICATION ENGINEERING LA English DT Article DE AEROSPACE; LIQUID LUBRICANTS; VACUUM ID STEEL AB The design and operation of a vacuum tribometer, based on a four-ball configuration, is described. This tribometer evaluates the tribological characteristics of liquid lubricants for space applications. Operating conditions were room temperature, loads to 1000N, speeds to 500 rpm, and pressures of 10(-6) Pa. Tests could also be run at atmospheric pressure with air or nitrogen. Some typical test results are included. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. CEDARVILLE COLL,CEDARVILLE,OH. RP MASUKO, M (reprint author), TOKYO INST TECHNOL,TOKYO 152,JAPAN. NR 13 TC 7 Z9 7 U1 0 U2 0 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 1994 VL 50 IS 11 BP 871 EP 875 PG 5 WC Engineering, Mechanical SC Engineering GA PQ518 UT WOS:A1994PQ51800006 ER PT J AU ARRIGO, KR AF ARRIGO, KR TI IMPACT OF OZONE DEPLETION ON PHYTOPLANKTON GROWTH IN THE SOUTHERN-OCEAN - LARGE-SCALE SPATIAL AND TEMPORAL VARIABILITY SO MARINE ECOLOGY PROGRESS SERIES LA English DT Article DE ANTARCTICA; PRIMARY PRODUCTION; OZONE; UV INHIBITION ID ULTRAVIOLET-RADIATION; SEA ICE; PHOTOSYNTHESIS; IRRADIANCE; INHIBITION; ANTARCTICA; ABSORPTION; WATERS; MODEL AB A numerical model has been used to assess the impact of decreased O-3 concentrations over the Southern Ocean on phytoplankton production. The model includes components describing (1) atmospheric spectral radiation (280 to 700 nm) as a function of time and latitude, (2) in-water biooptics, and (3) primary production, as determined by the depth-dependent spectral distribution of ambient irradiance and the action spectrum for photosynthesis. Model results show that in early spring, a 50% reduction in stratospheric O-3 enhanced the integrated production within the euphotic zone by similar to 9% at 75 degrees S and by 0.5% at 50 degrees S, due to the increased transmission of photosynthetically usable radiation, PUR (400 to 700 nm). Later, as solar zenith angles decreased, UV inhibition overcame PUR-induced enhancement, and integrated phytoplankton production was inhibited, but by less than 1.0%. A similar pattern resulted when observed O-3 concentrations were used as model input, although the PWR-induced enhancement effect was substantially reduced. UV inhibition at normal O-3 concentrations was most severe at the sea surface and dominated by UVA, reducing production by a maximum oi 54%. Simulating a 50% decrease in O-3 concentration reduced production at the sea surface by at most an additional 13%. However, integrating the effect throughout the Light cycle and down to the base of the euphotic zone reduced the computed deleterious effect of added UVB to < 1.0%. Because sea ice extent is greatest when and where O-3 is at its minimum, and major phytoplankton blooms generally occur well after ozone concentrations have rebounded to normal levels, the potential impact of increased UVB transmission in the Southern Ocean is further reduced. It is concluded that increased transmission of UVB beneath the ozone hole would result in only a slight incremental increase in UV inhibition oi depth-integrated phytoplankton production over that which occurs naturally. RP ARRIGO, KR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, OCEANS & ICE BRANCH, CODE 971, GREENBELT, MD 20771 USA. NR 35 TC 62 Z9 63 U1 0 U2 10 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 1994 VL 114 IS 1-2 BP 1 EP 12 DI 10.3354/meps114001 PG 12 WC Ecology; Marine & Freshwater Biology; Oceanography SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Oceanography GA PU498 UT WOS:A1994PU49800001 ER PT J AU ZHOU, W DUDLEY, M WU, J SU, CH VOLZ, MP GILLIES, DC SZOFRAN, FR LEHOCZKY, SL AF ZHOU, W DUDLEY, M WU, J SU, CH VOLZ, MP GILLIES, DC SZOFRAN, FR LEHOCZKY, SL TI SYNCHROTRON TOPOGRAPHY CHARACTERIZATION OF ZNTE SINGLE-CRYSTALS SO MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY LA English DT Article DE SYNCHROTRON TOPOGRAPHY; GROWTH DEFECT; SINGLE CRYSTAL; TWINS ID TRAVELING HEATER METHOD; GROWTH AB (111) Wafers sliced from a single-crystal boule of ZnTe grown by horizontal physical vapor transport have been characterized using synchrotron white-beam X-ray topography. The presence of dislocation slip bands, subgrain structures, and long, thin 180 degrees rotational twin lamellae was revealed. Distorted regions exhibiting radial lattice rotation were also observed near the crystal edges. One of these regions is clearly the source for the generation of some of the slip bands observed in the crystals. The slip bands were observed to break up the ordered dislocation cell structures comprising the subgrain boundaries, indicating that the dislocation cell structure appears earlier during the growth process, and that the slop dislocations appear later, perhaps during the postgrowth cooling process. This may also be an indication that modification of the cooling rate could have a significant effect on the final defect microstructure, with for example more rapid cooling giving rise to more slip which could obscure the true growth-defect microstructure. The initiation of slip at regions of stress concentration, such as the lateral twin boundaries, and at the junctions of subgrain boundaries and twin boundaries, was also revealed. The asymmetric distribution of slip bands either side of the twinned region of crystal suggests that twin boundaries can act as barriers for slip. Several types of detailed twin boundary configuration were determined form the topographs. Using a combination of white-beam X-ray topography and Nomarski interference microscopy, the three-dimensional shapes of the twin boundaries were determined. Approximate atomic structures at these boundaries are presented. Possible mechanisms for the production of a long thin twin lamella, oriented at a small angle to the growth axis, are discussed. C1 SUNY STONY BROOK,DEPT MAT SCI & ENGN,STONY BROOK,NY 11794. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NR 20 TC 5 Z9 5 U1 0 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0921-5107 J9 MAT SCI ENG B-SOLID JI Mater. Sci. Eng. B-Solid State Mater. Adv. Technol. PD NOV PY 1994 VL 27 IS 2-3 BP 143 EP 153 DI 10.1016/0921-5107(94)90135-X PG 11 WC Materials Science, Multidisciplinary; Physics, Condensed Matter SC Materials Science; Physics GA PT359 UT WOS:A1994PT35900012 ER PT J AU AHMED, S MCKANNAN, EC AF AHMED, S MCKANNAN, EC TI CONTROL OF GAMMA' MORPHOLOGY IN NICKEL-BASE SUPERALLOYS THROUGH ALLOY DESIGN AND DENSIFICATION PROCESSING UNDER ELECTRIC-FIELD SO MATERIALS SCIENCE AND TECHNOLOGY LA English DT Article AB The design and development of the future generation of nickel base superalloys for the demanding environments of rocket engines should be based on the metallurgical and structural characteristics of the gamma' phase. The distinctive features of this phase (e.g. strength, stability, size, shape, amount, distribution, uniformity, and order) can be controlled when a superalloy is appropriately designed and subsequently processed by an innovative solidification processing method. This concept has been successfully applied in the design and development of a superalloy. The resulting microstructure is almost perfect requiring no further treatment or processing. C1 YOUNGSTOWN STATE UNIV,DIV MAT ENGN,YOUNGSTOWN,OH 44555. RP AHMED, S (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,MAT & PROC LAB,HUNTSVILLE,AL 35812, USA. NR 14 TC 18 Z9 25 U1 0 U2 0 PU INST MATERIALS PI LONDON PA 1 CARLTON HOUSE TERRACE, LONDON, ENGLAND SW1Y 5DB SN 0267-0836 J9 MATER SCI TECH SER JI Mater. Sci. Technol. PD NOV PY 1994 VL 10 IS 11 BP 941 EP 946 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA QN415 UT WOS:A1994QN41500003 ER PT J AU LIN, HH OSWALD, FB TOWNSEND, DP AF LIN, HH OSWALD, FB TOWNSEND, DP TI DYNAMIC LOADING OF SPUR GEARS WITH LINEAR OR PARABOLIC TOOTH PROFILE MODIFICATIONS SO MECHANISM AND MACHINE THEORY LA English DT Article AB A computer simulation was conducted to investigate the effects of both linear and parabolic tooth profile modification on the dynamic response of low-contact-ratio spur gears. The effect of the total amount of modification and the length of the modification zone were studied at various loads and speeds to find the optimal profile modification for minimal dynamic loading. Design charts consisting of normalized maximum dynamic load curves were generated for gear systems operated at various loads and with different tooth profile modification. An optimum profile modification can be determined from these design charts to minimize the dynamic loads of spur gear systems. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP LIN, HH (reprint author), MEMPHIS STATE UNIV, DEPT MECH ENGN, MEMPHIS, TN 38152 USA. NR 16 TC 42 Z9 59 U1 2 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-114X J9 MECH MACH THEORY JI Mech. Mach. Theory PD NOV PY 1994 VL 29 IS 8 BP 1115 EP 1129 PG 15 WC Engineering, Mechanical SC Engineering GA PJ582 UT WOS:A1994PJ58200003 ER PT J AU DEGROH, HC AF DEGROH, HC TI UNDERCOOLING-INDUCED MACROSEGREGATION IN DIRECTIONAL SOLIDIFICATION SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID NH4CL-H2O ANALOG CASTINGS; HETEROGENEOUS NUCLEATION; MODEL ASPECTS; SN; TRANSITION; PRESSURE; DENDRITE; SYSTEMS; ALLOYS AB The accepted primary mechanism for. causing macrosegregation in directional solidification (DS) is thermal and solutal convection in the liquid. This article demonstrates the effects of undercooling and nucleation on macrosegregation and shows that undercooling, in some cases,can be the cause of end-to-end macrosegregation. Alloy ingots of Pb-Sn were directionally solidified upward and downward, with and without undercooling. A thermal gradient of about 5.1 K/cm and a cooling rate of 7.7 K/h were used. Crucibles of borosilicate glass, stainless steel with Cu bottoms, and fused silica were used. High undercoolings were achieved in the glass crucibles, and very,low undercoolings were achieved in the steel/Cu crucible. During undercooling, large, coarse Pb dendrites were found to be present. Large amounts of macrosegregation developed in the undercooled eutectic and hypoeutectic alloys. This segregation was found to be due to the nucleation and growth of primary Pb-rich dendrites, continued coarsening of Pb dendrites during undercooling of the interdendritic liquid, Sn enrichment of the liquid, and dendritic fragmentation and settling during and after recalescence. Eutectic ingots that solidified with no undercooling had no macrosegregation, because both Pb and Sn phases were effectively nucleated at the start of solidification, thus initiating the growth of solid of eutectic composition. It is thus shown that undercooling and single-phase nucleation can cause significant macrosegregation by increasing the amount of solute rejected into the liquid and by the movement of unattached dendrites and dendrite fragments, and that macrosegregation in excess of what would be expected due to diffusion transport is not necessarily caused by: convection in the liquid. RP DEGROH, HC (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 49 TC 4 Z9 4 U1 0 U2 3 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD NOV PY 1994 VL 25 IS 11 BP 2507 EP 2516 PG 10 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA PN132 UT WOS:A1994PN13200019 ER PT J AU TREIMAN, AH BERKLEY, JL AF TREIMAN, AH BERKLEY, JL TI IGNEOUS PETROLOGY OF THE NEW UREILITES NOVA-001 AND NULLARBOR-010 SO METEORITICS LA English DT Article ID ORIGIN; METEORITES; MINERALOGY; EVOLUTION; VOLCANISM AB The Nova 001 [= Nuevo Mercurio (b)] and Nullarbor 010 meteorites are ureilites, both of which contain euhedral graphite crystals. The bulk of the meteorites are olivine (Fo(79)) and pyroxenes (Wo(9)En(73)Fs(18), Wo(3)En(77)Fs(20)), with a few percent graphite and minor amounts of troilite, Ni-Fe metal, and possibly diamond. The rims of olivine grains are reduced (to Fo(91)) and contain abundant blebs of Fe metal. Silicate mineral grains are equant, anhedral, up to 2 mm across, and lack obvious preferred orientations. Euhedral graphite crystals (to 1 mm x 0.3 mm) are present at silicate grain boundaries, along boundaries and protruding into the silicates, and entirely within silicate mineral grains. Graphite euhedra are also present as radiating clusters and groups of parallel plates grains embedded in olivine; no other ureilite has comparable graphite textures. Minute lumps within graphite grains are possibly diamond, inferred to be a result of shock. Other shock effects are limited to undulatory extinction and fracturing. Both ureilites have been weathered significantly. Considering their similar mineralogies, identical mineral compositions, and identical unusual textures, Nova 001 and Nullarbor 010 are probably paired. Based on olivine compositions, Nova 001 and Nullarbor 010 are in Group 1 (FeO-rich) of Berkley et al. (1980). Silicate mineral compositions are consistent with those of other known ureilites. The presence of euhedral graphite crystals within the silicate minerals is consisted with an igneous origin, and suggests that large proportions of silicate magma were present locally and crystallized in situ. C1 NASA,LYNDON B JOHNSON SPACE CTR,NATL RES COUNCIL ASSOCIATE,SN-2,HOUSTON,TX 77058. SUNY COLL FREDONIA,DEPT GEOSCI,FREDONIA,NY 14063. NR 30 TC 23 Z9 24 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1994 VL 29 IS 6 BP 843 EP 848 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PR846 UT WOS:A1994PR84600009 ER PT J AU MIYAMOTO, M ZOLENSKY, ME AF MIYAMOTO, M ZOLENSKY, ME TI INFRARED DIFFUSE-REFLECTANCE SPECTRA OF CARBONACEOUS CHONDRITES - AMOUNT OF HYDROUS MINERALS SO METEORITICS LA English DT Article ID AQUEOUS ALTERATION; MATRIX MINERALOGY; PARENT BODIES; METEORITES; CARBONATES AB Infrared diffuse reflectance spectra (2.53-25 mu m) of some carbonaceous (C) chondrites were measured. The integrated intensity of the absorption bands near 3 pm caused by hydrous minerals were compared with the modal content of hydrous minerals for the meteorites. The CM and CI chondrites show larger values of the integrated intensity than those of the unique C chondrites Y82162, Y86720 and B7904, suggesting that the amount of hydrous minerals in the CM and CI chondrites is larger, which supports the contention that hydrous minerals were dehydrated by thermal metamorphism in the unique chondrites. Orgueil (CI) has the largest Value of the integrated intensity among the C chondrites we measured and shows a sharp absorption band at 3685 cm(-1) (2.71 mu m) that is not seen in the spectra of the CM chondrites. There is an excellent correlation between the observed hydrogen content in C chondrites and the integrated intensity. The CM chondrites show a wide variation in the strength of absorption bands at 1470 cm(-1) (6.8 mu m), despite the similarity in absorption features near 3 mu m for all CM chondrites. The 1470 cm(-1) band could be due to the presence of some hydrocarbons but may also be a result of terrestrial alteration processes. C1 NASA,LYNDON B JOHNSON SPACE CTR,PLANT SCI BRANCH,HOUSTON,TX 77058. RP MIYAMOTO, M (reprint author), UNIV TOKYO,GRAD SCH SCI,INST MINERAL,BUNKYO KU,TOKYO 113,JAPAN. NR 36 TC 28 Z9 28 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1994 VL 29 IS 6 BP 849 EP 853 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PR846 UT WOS:A1994PR84600010 ER PT J AU WENTWORTH, SJ GOODING, JL AF WENTWORTH, SJ GOODING, JL TI CARBONATES AND SULFATES IN THE CHASSIGNY METEORITE - FURTHER EVIDENCE FOR AQUEOUS CHEMISTRY ON THE SNC PARENT PLANET SO METEORITICS LA English DT Article ID COMPONENTS AB Scanning electron microscopy and energy-dispersive X-ray spectrometry of untreated interior chips from three different specimens of the Chassigny meteorite confirm the presence of discrete grains of Ca-carbonate, Mg-carbonate, and Ca-sulfate. Morphologies of these salt grains suggest that the Ca-carbonate is calcite (CaCO3) and that the Ca-sulfate is gypsum (CaSO4.2H(2)O) or bassanite (CaSO4.1/2H(2)O). The morphologic identification of the Mg-carbonate is equivocal, but rhombohedral and acicular crystal habits suggest magnesite and hydromagnesite, respectively. The salts in Chassigny occur as discontinuous veins in primary igneous minerals and are similar to those previously documented in the nakhlites, Nakhla and Lafayette, and in shergottite EETA79001. Unlike those in nakhlites, however, the Chassigny salts occur alone, without associated ferric oxides or aluminosilicate clays. Traces of Cl and P in Chassigny salts are consistent with precipitation of the salts from short-lived, saline, aqueous solutions that postdated igneous crystallization. In contrast with the clear case for nakhlites, stratigraphic evidence for a preterrestrial origin of the salts in Chassigny is ambiguous; however, a preterrestrial origin of the Chassigny salts best explains all available evidence. The water-precipitated salts provide clear physical evidence for the hypothesis, proposed by other workers, that the igneous amphiboles in Chassigny might have experienced isotope-exchange reactions with near-surface water, thereby compromising the original stable-isotope signature of any magmatic water in melt inclusions. C1 NASA,LYNDON B JOHNSON SPACE CTR,SN2,HOUSTON,TX 77058. LOCKHEED ENGN & SCI CO,C23,HOUSTON,TX 77058. NR 16 TC 43 Z9 43 U1 0 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1994 VL 29 IS 6 BP 860 EP 863 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PR846 UT WOS:A1994PR84600012 ER PT J AU YAU, K WEISSMAN, P YEOMANS, D AF YAU, K WEISSMAN, P YEOMANS, D TI METEORITE FALLS IN CHINA AND SOME RELATED HUMAN CASUALTY EVENTS SO METEORITICS LA English DT Article ID EARTH AB Statistics of witnessed and recovered meteorite falls found in Chinese historical texts for the period from 700 B.C. to AD, 1920 are presented. Several notable features can be seen in the binned distribution as a function of time. An apparent decrease in the number of meteorite reports in the 18th century is observed. An excess of observed meteorite falls in the period from 1840 to 1880 seems to correspond to a similar excess in European data. A chi(2) probability test suggests that the association between the two data sets are real. Records of human casualties and structural damage resulting from meteorite falls are also given. A calculation based on the number of casualty events in the Chinese meteorite records suggests that the probability of a meteorite striking a human is far greater than previous estimates. However, it is difficult to verify the accuracy of the reported casualty events. RP YAU, K (reprint author), CALTECH,JET PROP LAB,MS 169-237,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 47 TC 5 Z9 5 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1994 VL 29 IS 6 BP 864 EP 871 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PR846 UT WOS:A1994PR84600013 ER PT J AU NYQUIST, LE BANSAL, B WIESMANN, H SHIH, CY AF NYQUIST, LE BANSAL, B WIESMANN, H SHIH, CY TI NEODYMIUM, STRONTIUM AND CHROMIUM ISOTOPIC STUDIES OF THE LEW86010 AND ANGRA-DOS-REIS METEORITES AND THE CHRONOLOGY OF THE ANGRITE PARENT BODY SO METEORITICS LA English DT Article ID EARLY SOLAR-SYSTEM; CARBONACEOUS CHONDRITES; ANTARCTIC METEORITES; WEATHERING PRODUCTS; ALLENDE INCLUSIONS; RB-87-SR-87 METHOD; RB-SR; EVOLUTION; SM; TIME AB Neodymium, strontium, and chromium isotopic studies of the LEW86010 angrite established its absolute age and the formation interval between its crystallization and condensation of Allende CAIs from the solar nebula. Pyroxene and phosphate were found to contain similar to 98% of its Sm and Nd inventory. A conventional Sm-147-Nd-143 isochron yielded an age of 4.53 +/- 0.04 Ga (2 sigma) and epsilon(Nd)(143) = 0.45 +/- 1.1. An Sm-146-Nd-142 isochron gives initial Sm-146/Sm-144 = 0.0076 +/- 0.0009 and epsilon(Nd)(142) = -2.5 +/- 0.4. The Rb-Sr analyses give initial Sr-87/Sr-86 (I-Sr(87)) = 0.698972 +/- 8 and 0.698970 +/- 18 for LEW and ADOR, respectively, relative to Sr-87/Sr-86 = 0.71025 for NBS987. The difference, Delta I-Sr(87), between I-Sr(87) for the angrites and literature values for Allende CAIs, corresponds to similar to 9 Ma of growth in a solar nebula with a CI chondrite value of Rb-87/S-86 = 0.91, or similar to 5 Ma in a nebula with solar photospheric Rb-87/Sr-86 = 1.51. Excess Cr-53 from extinct Mn-53 (t(1/2) = 3.7 Ma) in LEW86010 corresponds to initial Mn-53/Mn-55 = 1.44 +/- 0.07 x 10(-6) and closure to Cr isotopic homogenization 18.2 +/- 1.7 Ma after formation of Allende inclusions, assuming initial Mn-53/Mn-55 = 4.4 +/- 1.0 x 10(-5) for the inclusions as previously reported by the Paris group (Birck and Allegre, 1988). The Sm-146/Sm-144 value found for LEW86010 corresponds to solar system initial (Sm-146/Sm-144)(0) = 0.0080 +/- 0.0009 for crystallization 8 Ma after Allende, the difference between Pb-Pb ages of angrites and Allende, or 0.0086 +/- 0.0009 for crystallization 18 Ma after Allende, using the Mn-Cr formation interval. The isotopic data are discussed in the context of a model in which an undifferentiated ''chondritic'' parent body formed from the solar nebula similar to 2 Ma after Allende CAIs and subsequently underwent differentiation accompanied by loss of volatiles. Parent bodies with Rb/Sr similar to that of CI, CM, or CO chondrites could satisfy the Cr and Sr isotopic systematics. If the angrite parent body had Rb/Sr similar to that of CV meteorites, it would have to form slightly later, similar to 2.6 Ma after the CAIs, to satisfy the Sr and Cr isotopic systematics. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77258. RP NYQUIST, LE (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN4,HOUSTON,TX 77058, USA. NR 73 TC 93 Z9 95 U1 0 U2 11 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1994 VL 29 IS 6 BP 872 EP 885 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PR846 UT WOS:A1994PR84600014 ER PT J AU KORANYI, DM GREEN, DA WARNER, PJ WALDRAM, EM PALMER, DM AF KORANYI, DM GREEN, DA WARNER, PJ WALDRAM, EM PALMER, DM TI SEARCH FOR A RADIO COUNTERPART TO THE GAMMA-RAY BURST GRB-920711 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE RADIATION MECHANISMS NONTHERMAL; GAMMA-RAYS BURSTS; RADIO CONTINUUM GENERAL ID 6C SURVEY; 7C SURVEY; 151 MHZ; VARIABILITY AB Observations have been made of the field of the gamma-ray burst of 1992 July 11 (GRB 920711) at 151 MHz using the CLFST, at several days and at about one year after the event. This field was also observed for the 6C survey in 1975. GRB 920711 was a particularly bright and well-localized gamma-ray burst, ideally suited to follow-up observations at othe wavelengths. No evidence for variability with respect to the 6C survey has been found within the noise limits of about 100 mJy at 4-arcmin resolution and 40 mJy at 1-arcmin resolution. An observing programme is in progress to search for radio variability in other GRB fields on time-scales of days and weeks, as well as to search for coincident radio bursts. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP KORANYI, DM (reprint author), MULLARD RADIO ASTRON OBSERV,CAVENDISH LAB,MADINGLEY RD,CAMBRIDGE CB3 0HE,ENGLAND. RI Green, David/E-9609-2010 OI Green, David/0000-0003-3189-9998 NR 24 TC 14 Z9 14 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 NOV 1 PY 1994 VL 271 IS 1 BP 51 EP 56 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP784 UT WOS:A1994PP78400011 ER PT J AU CHEN, C ROTTMAN, JW KOCH, SE AF CHEN, C ROTTMAN, JW KOCH, SE TI NUMERICAL SIMULATIONS OF UPSTREAM BLOCKING, COLUMNAR DISTURBANCES, AND BORES IN STABLY STRATIFIED SHEAR FLOWS OVER AN OBSTACLE SO MONTHLY WEATHER REVIEW LA English DT Article ID COORDINATE TRANSFORMATION; MODEL; MOUNTAINS; TOPOGRAPHY; DEPTH; FLUID; WAVES AB A two-dimensional, nonhydrostatic, elastic numerical model has been used to study the generation of gravity waves for a stably stratified shear flow over an obstacle. When a low-level wind shear is included in the simulation, we find that the predictions for noticeable upstream effects based on Froude number for a uniform flow are no longer accurate. Upstream effects are encountered in the form of upstream propagating columnar disturbances and internal bores away from the obstacle. The limited parameter space studies conducted in this study suggest that the ratio of the shear depth to the obstacle height (d/H), the obstacle aspect ratio (H/L), and the Froude number (U/NH) are instrumental in determining the strength and the existence of these upstream disturbances. Thus, the present theoretical and empirical understanding of the importance of the Froude number for determining the nature of upstream effects should be modified substantially to include additional nondimensional parameters when shear is present. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. NR 29 TC 5 Z9 5 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD NOV PY 1994 VL 122 IS 11 BP 2506 EP 2529 DI 10.1175/1520-0493(1994)122<2506:NSOUBC>2.0.CO;2 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PM969 UT WOS:A1994PM96900007 ER PT J AU TODLING, R COHN, SE AF TODLING, R COHN, SE TI SUBOPTIMAL SCHEMES FOR ATMOSPHERIC DATA ASSIMILATION BASED ON THE KALMAN FILTER SO MONTHLY WEATHER REVIEW LA English DT Article ID 4-DIMENSIONAL VARIATIONAL ASSIMILATION; METEOROLOGICAL DATA ASSIMILATION; NUMERICAL WEATHER PREDICTION; NORMAL MODE INITIALIZATION; OBJECTIVE ANALYSIS SCHEME; PRIMITIVE-EQUATION MODEL; RANGE FORECAST ERRORS; STATISTICAL STRUCTURE; OCEAN CIRCULATION; RADIOSONDE DATA AB This work is directed toward approximating the evolution of forecast error covariances for data assimilation. The performance of different algorithms based on simplification of the standard Kalman filter (KF) is studied. These are suboptimal schemes (SOSs) when compared to the KF, which is optimal for linear problems with known statistics. The SOSs considered here are several versions of optimal interpolation (OI), a scheme for height error variance advection, and a simplified KF in which the full height error covariance is advected. To employ a methodology for exact comparison among these schemes, a linear environment is maintained, in which a beta-plane shallow-water model linearized about a constant zonal flow is chosen for the test-bed dynamics. The results show that constructing dynamically balanced forecast error covariances rather than using conventional geostrophically balanced ones is essential for successful performance of any SOS. A posteriori initialization of SOSs to compensate for model-data imbalance sometimes results in poor performance. Instead, properly constructed dynamically balanced forecast error covariances eliminate the need for initialization. When the SOSs studied here make use of dynamically balanced forecast error covariances, the difference among their performances progresses naturally from conventional OI to the KF. In fact, the results suggest that even modest enhancements of OI, such as including an approximate dynamical equation for height error variances while leaving height error correlation structure homogenous, go a long way toward achieving the performance of the KF, provided that dynamically balanced cross-covariances are constructed and that model errors are accounted for properly. The results indicate that such enhancements are necessary if unconventional data are to have a positive impact. RP TODLING, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DATA ASSIMILAT OFF,CODE 9103,GREENBELT,MD 20771, USA. RI Cohn, Stephen/K-1954-2012 OI Cohn, Stephen/0000-0001-8506-9354 NR 74 TC 78 Z9 80 U1 2 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD NOV PY 1994 VL 122 IS 11 BP 2530 EP 2557 DI 10.1175/1520-0493(1994)122<2530:SSFADA>2.0.CO;2 PG 28 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PM969 UT WOS:A1994PM96900008 ER PT J AU HEYMSFIELD, GM FULTON, R AF HEYMSFIELD, GM FULTON, R TI PASSIVE MICROWAVE STRUCTURE OF SEVERE TORNADIC STORMS ON 16 NOVEMBER 1987 SO MONTHLY WEATHER REVIEW LA English DT Note ID UPPER-LEVEL STRUCTURE; RADIATIVE-TRANSFER; 183 GHZ; SATELLITE-OBSERVATIONS; PRECIPITATING CLOUD; CONVECTIVE SYSTEMS; DEEP CONVECTION; MODEL; RAINFALL; SIMULATIONS AB Passive microwave observations using the Special Sensor Microwave/Imager are presented for severe tornadic storms in the lower midwestern United States on 16 November 1987. These measurements are compared with Geostationary Operational Environmental Satellite infrared (IR) measurements for the same case. The IR observations had a classic ''V'' cold feature commonly associated with severe Midwest thunderstorms. The minimum microwave brightness temperatures at 86 GHz, which primarily respond to ice scattering by larger ice particles, were located in the convective region and the warm interior region of the anvil top, between the arms of the IR V feature. The interior warm region was the only portion of the entire anvil region that had high 86-GHz polarization difference temperatures. Microphysical implications of these multispectral observations are discussed. The observations suggests that there are large variations of ice microphysical characteristics spatially and vertically in the anvil region. These observations are discussed in the context of previous dynamical and microphysical hypotheses on the IR V feature. C1 SCI SYST & APPLICAT INC,LANHAM,MD. RP HEYMSFIELD, GM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MESOSCALE DYNAM & PRECIPITAT BRANCH,CODE 912,GREENBELT,MD 20771, USA. NR 32 TC 4 Z9 4 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD NOV PY 1994 VL 122 IS 11 BP 2587 EP 2595 DI 10.1175/1520-0493(1994)122<2587:PMSOST>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PM969 UT WOS:A1994PM96900011 ER PT J AU GORNITZ, V AF GORNITZ, V TI SCIENCE, ECONOMICS AND NORTH-SOUTH POLITICS IN THE CLIMATE-CHANGE CONVENTION - HAYES,P, SMITH,K SO NATURAL RESOURCES FORUM LA English DT Book Review C1 COLUMBIA UNIV,NEW YORK,NY 10027. RP GORNITZ, V (reprint author), GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA LINACRE HOUSE JORDAN HILL, OXFORD, OXON, ENGLAND OX2 8DP SN 0165-0203 J9 NAT RESOUR FORUM PD NOV PY 1994 VL 18 IS 4 BP 305 EP 306 PG 2 WC Environmental Sciences; Environmental Studies SC Environmental Sciences & Ecology GA QB144 UT WOS:A1994QB14400009 ER PT J AU JOHNSON, SW THEDINGA, JF FELDHAUSEN, AS AF JOHNSON, SW THEDINGA, JF FELDHAUSEN, AS TI JUVENILE SALMONID DENSITIES AND HABITAT USE IN THE MAIN-STEM SITUK RIVER, ALASKA, AND POTENTIAL EFFECTS OF GLACIAL FLOODING SO NORTHWEST SCIENCE LA English DT Article AB Densities and habitat use of juvenile coho salmon (Oncorhynchus kisutch), sockeye salmon (O. nerka), steelhead (O. mykiss), and Dolly Varden (Salvelinus malma) were determined in the main-stem Situk River, Alaska. Three habitat types (channel edges, willow edges, and debris pools) were sampled at two downstream sites (lower river) and at two upstream sites (upper river) biweekly from May to September and once in November 1989. For most species, fry (age 0) most often used channel edges with little cover, whereas parr (age greater-than-or-equal-to 1) almost exclusively occupied willow edges and debris pools. Within the same habitat types, densities were significantly greater for most species and life-history stages in the upper than in the lower river; steelhead parr, with densities similar in like habitats in the upper and lower river, were a notable exception. Peak fry densities (fish/100 m2) were 2,331 coho, 155 steelhead, and 14 sockeye, whereas peak parr densities were 281 coho, 82 steelhead, and 44 Dolly Varden. Mean length of fry and parr of all species was greater in the lower river than in the upper river. With baseline information from this study, fisheries managers can identify strategies to restore fish and habitat that could be impacted by flooding in the Situk River. Hubbard Glacier is expected to advance and dam Russell Fiord by the year 2000, and overflow from the fiord will flood the Situk River, drastically altering fish rearing habitat. RP JOHNSON, SW (reprint author), NOAA,NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,AUKE BAY LAB,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 0 TC 1 Z9 1 U1 1 U2 5 PU WASHINGTON STATE UNIV PRESS PI PULLMAN PA COOPER PUBLICATIONS BLDG, PULLMAN, WA 99164-5910 SN 0029-344X J9 NORTHWEST SCI JI Northwest Sci. PD NOV PY 1994 VL 68 IS 4 BP 284 EP 293 PG 10 WC Ecology SC Environmental Sciences & Ecology GA QD110 UT WOS:A1994QD11000008 ER PT J AU EVRENSELAMET, E ARPACI, VS CHAI, AT AF EVRENSELAMET, E ARPACI, VS CHAI, AT TI THERMOCAPILLARY-DRIVEN FLOW PAST THE MARANGONI INSTABILITY SO NUMERICAL HEAT TRANSFER PART A-APPLICATIONS LA English DT Article ID COMBINED BUOYANCY-DRIVEN; SURFACE-TENSION-DRIVEN; RECTANGULAR CAVITY; NUMERICAL-SIMULATION; COUPLED BUOYANCY; LIQUID LAYER; CONVECTION; STABILITY; CONTAMINATION; CONTAINER AB A top free liquid layer is heated from the bottom in a two-dimensional rectangular container with insulated side walls. The resulting thermocapillary motion is predicted by the projection method involving a Godunov-type discretization for convective terms. The velocity and temperature fields beyond those predictable via infinitesimal theories are discussed in terms of the Marangoni number, Prandtl number, Biot number, and aspect ratio. C1 UNIV MICHIGAN,DEPT MECH ENGN & APPL MECH,2250 GG BROWN,ANN ARBOR,MI 48109. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 33 TC 6 Z9 6 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 NOV PY 1994 VL 26 IS 5 BP 521 EP 535 DI 10.1080/10407789408956007 PG 15 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA PT615 UT WOS:A1994PT61500002 ER PT J AU HILSENRATH, E HERZIG, H WILLIAMS, DE BRUEGGE, CJ STIEGMAN, AE AF HILSENRATH, E HERZIG, H WILLIAMS, DE BRUEGGE, CJ STIEGMAN, AE TI EFFECTS OF SPACE-SHUTTLE FLIGHT ON THE REFLECTANCE CHARACTERISTICS OF DIFFUSERS IN THE NEAR-INFRARED, VISIBLE, AND ULTRAVIOLET REGIONS SO OPTICAL ENGINEERING LA English DT Article DE SPACE CONTAMINATION; OPTICS; DIFFUSERS; REFLECTANCE ID SPECTRALON AB Many remote sensing instruments employ diffuse targets for calibration. These targets usually consist of diffusers with high Lambertian characteristics illuminated by a calibrated irradiance source. There is increasing interest in conducting in-orbit radiance calibration checks of remote sensing instruments using sunlight reflected off a diffuser. We report on the effects of space flight on the reflectance properties of polytetrafluoroethylene (PTFE) and aluminum diffuser samples flown on three Space Shuttle flights. These experiments showed good stability of both diffuser types in the visible and near infrared but experienced measurable degradation in the ultraviolet. Degradation varied from flight to flight and seemed to be related to different levels of contamination experienced on the three flights. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP HILSENRATH, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. NR 15 TC 4 Z9 4 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 NOV PY 1994 VL 33 IS 11 BP 3675 EP 3682 DI 10.1117/12.181932 PG 8 WC Optics SC Optics GA PQ831 UT WOS:A1994PQ83100024 ER PT J AU CLARKE, KC BRASS, JA RIGGAN, PJ AF CLARKE, KC BRASS, JA RIGGAN, PJ TI A CELLULAR-AUTOMATON MODEL OF WILDFIRE PROPAGATION AND EXTINCTION SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID PRESCRIBED CHAPARRAL FIRE; EMISSIONS AB We propose a new model to predict the spatial and temporal behavior of wildfires. Fire spread and intensity were simulated using a cellular automaton model. Monte Carlo techniques were used to provide fire risk probabilities for areas where fuel loadings and topography are known. The model assumes predetermined or measurable environmental variables such as wind direction and magnitude, relative humidity, fuel moisture content, and air temperature. Implementation of the model allows the linking of fire monitoring using remotely sensed data, potentially in real time, to rapid simulations of predicted fire behavior. Calibration of the model is based on thermal infrared remotely sensed imagery of a test burn during 1986 in the San Dimas experimental forest. The model and its various implementations show distinct promise for real-time fire management and fire risk planning. C1 CUNY GRAD SCH & UNIV CTR,NEW YORK,NY 10036. NASA,AMES RES CTR,ECOSYST SCI & TECHNOL BRANCH,MOFFETT FIELD,CA 94035. US FOREST SERV,FOREST FIRE LAB,PACIFIC SW RES STN,RIVERSIDE,CA 92507. RP CLARKE, KC (reprint author), CUNY HUNTER COLL,DEPT GEOL & GEOG,695 PK AVE,NEW YORK,NY 10021, USA. RI Clarke, Keith/E-1863-2011 OI Clarke, Keith/0000-0001-5805-6056 NR 25 TC 90 Z9 98 U1 1 U2 14 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 NOV PY 1994 VL 60 IS 11 BP 1355 EP 1367 PG 13 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA PR263 UT WOS:A1994PR26300007 ER PT J AU CUCINOTTA, FA WILSON, JW AF CUCINOTTA, FA WILSON, JW TI AN INITIATION-PROMOTION MODEL OF TUMOR PREVALENCE FROM HIGH-CHARGE AND ENERGY RADIATIONS SO PHYSICS IN MEDICINE AND BIOLOGY LA English DT Article ID FISSION-SPECTRUM NEUTRONS; ACCELERATED HEAVY-IONS; MUTATION-INDUCTION; CARCINOGENESIS; CELLS; CANCER; INACTIVATION; MOUSE; MICE AB A repair/misrepair kinetic model for multiple radiation-induced lesions (mutation inactivation) is coupled to a two-mutation model of initiation-promotion in tissue to provide a parametric description of tumour prevalence in the mouse Harderian gland from high-energy and charge radiations. Track-structure effects are considered using an action-cross section model. Dose-response curves are described for gamma rays and relativistic ions, and good agreement with experiment is found. The effects of nuclear fragmentation are also considered for high-energy proton and alpha-particle exposures. The model described provides a parametric description of age-dependent cancer induction for a wide range of radiation fields. Radiosensitivity parameters found in the model for an initiation mutation (sigma(0) = 7.6 x 10(-10) cm(2) and D-0 = 148.0 Gy) are somewhat different than previously observed for neoplastic transformation of C3H10TI/2 cell cultures (sigma(0) = 0.7 x 10(-10) cm(2) and D-0 = 117.0 Gy). We consider the two hypotheses that radiation acts solely as an initiator or as both initiator and promoter and make model calculations for fractionation exposures from gamma rays and relativistic Fe ions. For fractionated Fe exposures, an inverse-dose-rate effect is provided by a promotion hypothesis with an increase of 30% or more, dependent on the dose level and fractionation schedule, using a mutation rate for promotion similar to that of single-gene mutations. RP CUCINOTTA, FA (reprint author), NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NR 43 TC 12 Z9 12 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0031-9155 J9 PHYS MED BIOL JI Phys. Med. Biol. PD NOV PY 1994 VL 39 IS 11 BP 1811 EP 1831 DI 10.1088/0031-9155/39/11/003 PG 21 WC Engineering, Biomedical; Radiology, Nuclear Medicine & Medical Imaging SC Engineering; Radiology, Nuclear Medicine & Medical Imaging GA PR186 UT WOS:A1994PR18600003 PM 11541517 ER PT J AU TRINH, EH ROBEY, JL AF TRINH, EH ROBEY, JL TI EXPERIMENTAL-STUDY OF STREAMING FLOWS ASSOCIATED WITH ULTRASONIC LEVITATORS SO PHYSICS OF FLUIDS LA English DT Article ID SPHERE; DROPS AB Steady-state acoustic streaming flow patterns have been observed during the operation of a variety of resonant single-axis ultrasonic levitators in a gaseous environment and in-the 20-37 kHz frequency range. Light sheet illumination and scattering from smoke particles have revealed primary streaming flows which display different characteristics at low and high sound pressure levels. Secondary macroscopic streaming cells around levitated samples are superimposed on the primary streaming flow pattern generated by the standing wave. These recorded flows are quite reproducible, and are qualitatively the same for a variety of levitator physical geometries. An onset of flow instability can also be recorded in nonisothermal systems, such as levitated spot-heated samples when the resonance conditions are not exactly Satisfied. A preliminary qualitative interpretation of these experimental results-is presented in terms of the superposition of three discrete sets of circulation cells operating an different spatial scales. These relevant length scales are the acoustic wavelength, the levitated sample size, and finally the acoustic boundary layer thickness. This approach fails, however, to explain the streaming flow-field morphology around liquid drops levitated on Earth. Observation of the interaction between the flows cells and the levitated samples also suggests the existence of a steady-state torque induced by the streaming flows. RP TRINH, EH (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 33 TC 66 Z9 66 U1 0 U2 14 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD NOV PY 1994 VL 6 IS 11 BP 3567 EP 3579 DI 10.1063/1.868415 PG 13 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PP475 UT WOS:A1994PP47500009 ER PT J AU KAMOTANI, Y OSTRACH, S PLINE, A AF KAMOTANI, Y OSTRACH, S PLINE, A TI ANALYSIS OF VELOCITY DATA TAKEN IN SURFACE-TENSION DRIVEN CONVECTION EXPERIMENT IN MICROGRAVITY SO PHYSICS OF FLUIDS LA English DT Article ID OSCILLATORY THERMOCAPILLARY CONVECTION; MARANGONI NUMBER CONVECTION; SQUARE CAVITY; FLOWS AB Some velocity field results from the Surface Tension Driven Convection Experiment (STDCE) that was conducted aboard the USML-1 Spacelab in 1992 are reported. 10 cSt silicone oil Was placed in an open circular container (10 cm widex5 cm deep) and heated either by a cylindrical heater (1.11 cm diam) placed along the centerline or by a CO2 laser to induce thermocapillary flow; Tests were conducted under varieties of powers, laser beam diameters, and free-surface shapes. The flow field was studied by flow visualization and the data were analyzed by a PTV technique. The results from the velocity measurement are presented and the effects of heating mode and free-surface shape on the flow are discussed. The results are also compared with a numerical analysis conducted in conjunction with the experiment. Good agreement is shown. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44106. RP KAMOTANI, Y (reprint author), CASE WESTERN RESERVE UNIV,DEPT MECH & AEROSP ENGN,CLEVELAND,OH 44106, USA. NR 14 TC 35 Z9 36 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD NOV PY 1994 VL 6 IS 11 BP 3601 EP 3609 DI 10.1063/1.868432 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PP475 UT WOS:A1994PP47500012 ER PT J AU SINGER, BA JOSLIN, RD AF SINGER, BA JOSLIN, RD TI METAMORPHOSIS OF A HAIRPIN VORTEX INTO A YOUNG TURBULENT SPOT SO PHYSICS OF FLUIDS LA English DT Article ID BOUNDARY-LAYER SEPARATION; PRESSURE-GRADIENT; PLANE POISEUILLE; FLOW; TRANSITION; VORTICES AB Direct numerical simulation was used to study the formation and growth of a hairpin vortex in a flat-plate boundary layer and its later development into a young turbulent spot. Fluid injection through a slit in the wall triggered the initial vortex. The legs of the vortex were stretched into a hairpin shape as it traveled downstream. Multiple hairpin vortex heads developed between the stretched legs. New vortices formed beneath the streamwise-elongated vortex legs. The continued development of additional vortices resulted in the formation of a traveling region of highly disturbed flow with an arrowhead shape similar to that of a turbulent spot. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. RP SINGER, BA (reprint author), NASA, HIGH TECHNOL CORP, LANGLEY RES CTR, MAIL STOP 156, HAMPTON, VA 23681 USA. NR 39 TC 57 Z9 58 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD NOV PY 1994 VL 6 IS 11 BP 3724 EP 3736 DI 10.1063/1.868363 PG 13 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PP475 UT WOS:A1994PP47500024 ER PT J AU MATHIOWETZ, AM JAIN, A KARASAWA, N GODDARD, WA AF MATHIOWETZ, AM JAIN, A KARASAWA, N GODDARD, WA TI PROTEIN SIMULATIONS USING TECHNIQUES SUITABLE FOR VERY LARGE SYSTEMS - THE CELL MULTIPOLE METHOD FOR NONBOND INTERACTIONS AND THE NEWTON-EULER INVERSE MASS OPERATOR METHOD FOR INTERNAL COORDINATE DYNAMICS SO PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS LA English DT Article DE CELL MULTIPOLE METHOD; NEWTON-EULER INVERSE MASS OPERATOR ID REFINED CRYSTAL-STRUCTURE; MOLECULAR-DYNAMICS; RESOLUTION; CONSTRAINTS; EQUATIONS; ALGORITHM; COULOMB; MOTION AB Two new methods developed for molecular dynamics simulations of very large proteins are applied to a series of proteins ranging up to the protein capsid of tomato bushy stunt virus (TBSV). For molecular dynamics of very large proteins and polymers, it is useful to carry out the dynamics using internal coordinates (say, torsions only) rather than Cartesian coordinates. This allows larger time steps, eliminates problems with the classical description of high energy modes, and focuses on the important degrees of freedom. The resulting equation of motion has the form M(theta)theta + L(theta,theta) = T(theta) where for T is the vector of generalized forces, M(theta) is the moments of inertia tenser, theta is the vector of torsions, and L is a vector containing Coriolis forces and nonbond forces. The problem is that to calculate the acceleration vector theta from M, L, and T requires inverting M(theta), an order N-3 calculation. Since the number of degrees of freedom might be 300,000 for a million atom system, solving these equations every time step is impractical, restricting internal coordinate methods to small systems. The new method, Newton-Euler Inverse Mass Operator (NEIMO) dynamics, constructs the torsional accelerations vector theta = M(-1)(T - L) directly by an order N process, allowing internal-coordinate dynamics to be solved for super larger (million atom) systems. The first use of the NEIMO method for molecular dynamics of proteins is presented here. A second serious difficulty for large proteins is calculation of the nonbond forces. We report here the first application to proteins of the new Cell Multipole Method (CMM) to evaluate the Coulomb and van der Waals interactions. The cost of CMM scales linearly with the number of particles while retaining an accuracy significantly better than standard nonbond methods (involving cutoffs). Results for NEIMO and CMM are given for simulations of a wide range of peptide and protein systems, including the protein capsid of TBSV with 488,000 atoms. The computational times for NEIMO and CMM are demonstrated to scale linearly with size. With NEIMO the dynamics time steps can be as large as 20 fs (for small peptides), much larger than possible with standard Cartesian coordinate dynamics. For TBSV we considered both the normal form and the high pH form, in which the Ca2+ ions are removed. These calculations lead to a contraction of the protein for both forms (probably because of ignoring the RNA core not observed in the X-ray). (C) 1994 Wiley-Liss, Inc. C1 CALTECH, BECKMAN INST 13974, CTR MAT & MOLEC SIMULAT, DIV CHEM & CHEM ENGN CN 8921, PASADENA, CA 91125 USA. CALTECH, JET PROP LAB, PASADENA, CA 91125 USA. NR 35 TC 73 Z9 74 U1 0 U2 2 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0887-3585 EI 1097-0134 J9 PROTEINS JI Proteins PD NOV PY 1994 VL 20 IS 3 BP 227 EP 247 DI 10.1002/prot.340200304 PG 21 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA QH319 UT WOS:A1994QH31900003 PM 7892172 ER PT J AU GREASON, MR OFFENBERG, JD CORNETT, RH HILL, RS STECHER, TP AF GREASON, MR OFFENBERG, JD CORNETT, RH HILL, RS STECHER, TP TI CORRECTING THE DISTORTION OF IMAGES TAKEN WITH THE ULTRAVIOLET IMAGING TELESCOPE SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article AB The Ultraviolet Imaging Telescope cameras include two-stage magnetically focused image intensifiers that introduce small but significant geometrical distortions into the data. These distortions, which create positional offsets as large as 25 arcsec at the field edges, are corrected by the procedure described here to 2-3 arcsec, approximately the resolution of the images. The distortion is measured by comparing and correcting UIT images to digitized Guidestar survey plates of the same fields. Two-dimensional third-order polynomials are used to model the distortion. The models assume that the distortion is an instrumental effect, independent of mission elapsed time and target, and that the effect of distortion in the center of each field is minimal. The models are used to improve computed astrometric plate solutions and to remove the geometric distortion while transforming the image to a standard north-up, east-left orientation. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NR 4 TC 11 Z9 11 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 1994 VL 106 IS 705 BP 1151 EP 1156 DI 10.1086/133492 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PT669 UT WOS:A1994PT66900006 ER PT J AU WILSON, JW SHAVERS, MR BADAVI, FF MILLER, J SHINN, JL COSTEN, RC AF WILSON, JW SHAVERS, MR BADAVI, FF MILLER, J SHINN, JL COSTEN, RC TI NONPERTURBATIVE METHODS IN HZE PROPAGATION SO RADIATION RESEARCH LA English DT Article ID 670A MEV NE-20; TRANSPORT-THEORY; FRAGMENTATION; DEPTH; WATER AB An analytical solution to the perturbative multiple collision series of a fragmenting HZE ion beam has limited usefulness since the first collision term has several hundred contributions, the second collision term has tens of thousands of contributions, and each successive collision term progresses to unwieldy computational proportions. Our previous work has revealed the multiple collision terms in the straight-ahead approximation to be simple products of a spatially dependent factor times a linear energy-dependent factor of limited domain and unit normalization. The properties of these forms allow the development of the nonperturbative summation of the series to all orders assuming energy-independent nuclear cross sections as matrix products of a scaled Green's function described herein. This nonperturbative Green's function with multiple scattering correction factors compares well with experiments using 670 MeV/u neon-20 ion beams in thick water targets. C1 UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. CHRISTOPHER NEWPORT UNIV,NEWPORT NEWS,VA 23601. RP WILSON, JW (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 20 TC 13 Z9 13 U1 0 U2 1 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD NOV PY 1994 VL 140 IS 2 BP 241 EP 248 DI 10.2307/3578908 PG 8 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA PN944 UT WOS:A1994PN94400012 PM 7938473 ER PT J AU YUEH, SH KWOK, R NGHIEM, SV AF YUEH, SH KWOK, R NGHIEM, SV TI POLARIMETRIC SCATTERING AND EMISSION PROPERTIES OF TARGETS WITH REFLECTION SYMMETRY SO RADIO SCIENCE LA English DT Article ID MODEL AB This paper investigates the symmetry of polarimetric scattering and emission coefficients of media with reflection symmetry. A reflection operator is defined and is used to create the images of electromagnetic fields and sources. The image fields satisfy Maxwell's equations, meaning that Maxwell's equations are invariant under the described reflection operations. By applying the reflection operations to media with reflection symmetry, the symmetry properties of the Stokes parameters, characterizing the polarization state of thermal emissions, are shown to agree with existing experimental data. The first two Stokes parameters are symmetric with respect to the reflection plane, while the third and fourth Stokes parameters have odd symmetry. In active remote sensing, the symmetry properties of the polarimetric scattering matrix elements of deterministic targets and the polarimetric covariance matrix elements of random media or distributed targets are examined. For deterministic targets, the cross-polarized responses are odd functions with respect to the symmetry direction, whereas the copolarized responses are even functions. For distributed targets or random media, it is found that the correlations of copolarized and cross-polarized responses are antisymmetric with respect to the reflection plane, while the other covariance matrix elements are symmetric. Consequently, in the cases of backscatter, the copolarized and cross-polarized components are completely uncorrelated when the incidence direction is on the symmetry plane. The derived symmetry properties of polarimetric backscattering coefficients agree with the predictions of a two-scale surface scattering model and existing sea surface HH and VV backscatter data. Finally, the conditions for a general type of media, i.e., bianisotropic media, to be reflection symmetric are examined. RP YUEH, SH (reprint author), CALTECH,JET PROP LAB,MAIL STOP 300-235,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 21 TC 51 Z9 54 U1 0 U2 4 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 1994 VL 29 IS 6 BP 1409 EP 1420 DI 10.1029/94RS02228 PG 12 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA PT165 UT WOS:A1994PT16500005 ER PT J AU WHITLOCK, CH LECROY, SR WHEELER, RJ AF WHITLOCK, CH LECROY, SR WHEELER, RJ TI NARROW-BAND ANGULAR REFLECTANCE PROPERTIES OF THE ALKALI FLATS AT WHITE-SANDS, NEW-MEXICO SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SURFACE REFLECTANCE; CALIBRATION; CHANNELS; RADIANCE; NOAA-7 AB Results from helicopter measurements of the angular properties of surface reflectance for the alkali flats regions of the White Sands Missile Range are presented for the wavelength interval of 0.4 to 0.85 mu m. This work was performed to allow accurate radiative transfer calculations over the region. Detailed tables and interpolation equations are given that permit other investigators to perform satellite calibrations over the alkali flats site. The effects of wavelength and soil moisture on narrowband angular reflectance are also investigated. Although there is a spectral variation in surface albedo, there is little spectral effect in Anisotropic Factor except in the forward-scattering peak at solar zenith angles greater than 60 degrees. The magnitude of the forward-scattering peak is also sensitive to soil moisture, with wet conditions causing a larger peak. The significance of this result is that angular reflectance properties at the center of the alkali flats usually will be different than those at the flats edge because moisture differences typically exist. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP WHITLOCK, CH (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MS 420,HAMPTON,VA 23665, USA. NR 25 TC 3 Z9 3 U1 1 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD NOV PY 1994 VL 50 IS 2 BP 171 EP 181 DI 10.1016/0034-4257(94)90043-4 PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA PW065 UT WOS:A1994PW06500009 ER PT J AU BACKES, PG BEAHAN, J LONG, MK STEELE, RD BON, B ZIMMERMAN, W AF BACKES, PG BEAHAN, J LONG, MK STEELE, RD BON, B ZIMMERMAN, W TI A PROTOTYPE GROUND-REMOTE TELEROBOT CONTROL-SYSTEM SO ROBOTICA LA English DT Article; Proceedings Paper CT 4th International Symposium on Robotics and Manufacturing (ISRAM) CY NOV, 1992 CL SANTA FE, NM DE TELEROBOT CONTROL; MOTES; COMMAND PARAMETERIZATION; SPACE STATION AB A local-remote telerobot control system is described which is being developed for time-delayed ground-remote control of space telerobotic systems. The system includes a local site operator interface for interactive command building and sequencing for supervised autonomy and a remote site: the Modular Telerobot Task Execution System (MOTES), to provide the remote site task execution capability. The local site system also provides stereo graphics overlay on video with interactive update of the remote environmental model. The operator selects objects in the environment to interact with and skill types to specify the tasks to be performed, such as grasping a module or opening a door. The information needed by a skill to operate on a specific object is stored in a knowledge base or input by the operator. The remote site system supports supervised autonomy, shared control, and teleoperation for a redundant manipulator. The system is capable of nominal task execution as well as monitoring and reflex motion. A command interpreter similar to one used on robotic spacecraft is used to interpret commands received from the local site. Execution utilizes multiple control modules which execute based upon command parameterization. RP BACKES, PG (reprint author), JET PROP LAB,MAIL STOP 198-219,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0263-5747 J9 ROBOTICA JI Robotica PD NOV-DEC PY 1994 VL 12 BP 481 EP 490 PN 6 PG 10 WC Robotics SC Robotics GA PT555 UT WOS:A1994PT55500002 ER PT J AU JOHNSON, AR QUIGLEY, CJ MEAD, JL AF JOHNSON, AR QUIGLEY, CJ MEAD, JL TI LARGE-STRAIN VISCOELASTIC CONSTITUTIVE MODELS FOR RUBBER .1. FORMULATIONS SO RUBBER CHEMISTRY AND TECHNOLOGY LA English DT Article ID ELASTICITY AB Constitutive models for large strain isothermal viscoelastic deformations of rubber are reviewed. The models discussed are for materials which have separable long and short term stresses, and for which the short term stresses have separable time and strain effects. They include the history integral model, an internal stress variable model, an internal stretch variable model, and an internal solid model. The internal stretch variable model and the internal solid model were motivated by molecular descriptions of rubber viscoelasticity. The material tests required to determine the constants for these large strain models are discussed. The classical problem of determining a rubber energy density function, used to describe both the long term and short term energy in these models, is reviewed. A method to assure Drucker stability, a commonly overlooked issue, is presented for experimentally determined Rivlin energy density function expansions. Also, an improved method for determining the coefficients of a Prony series, which defines a material's relaxation time spectrum, from experimental relaxation data is presented. C1 USA,RES LAB,MAT DIRECTORATE,AMSRL,MA,PC,WATERTOWN,MA 02172. RP JOHNSON, AR (reprint author), NASA,LANGLEY RES CTR,VEHICLE STRUCT DIRECTORATE,USA,RES LAB,HAMPTON,VA 23681, USA. NR 30 TC 35 Z9 35 U1 0 U2 5 PU AMER CHEMICAL SOC INC PI AKRON PA RUBBER DIV UNIV AKRON PO BOX 499, AKRON, OH 44309-0499 SN 0035-9475 J9 RUBBER CHEM TECHNOL JI Rubber Chem. Technol. PD NOV-DEC PY 1994 VL 67 IS 5 BP 904 EP 917 DI 10.5254/1.3538721 PG 14 WC Polymer Science SC Polymer Science GA QE808 UT WOS:A1994QE80800015 ER PT J AU MCLAUGHLIN, WI AF MCLAUGHLIN, WI TI RESOLVING ZENO PARADOXES SO SCIENTIFIC AMERICAN LA English DT Article ID NONSTANDARD ANALYSIS RP MCLAUGHLIN, WI (reprint author), JET PROPULS LAB,PASADENA,CA, USA. NR 5 TC 4 Z9 4 U1 0 U2 2 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 SN 0036-8733 J9 SCI AM JI Sci.Am. PD NOV PY 1994 VL 271 IS 5 BP 84 EP 89 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PM589 UT WOS:A1994PM58900023 ER PT J AU BATCHELOR, D AF BATCHELOR, D TI QUASI-STEREOSCOPIC IMAGING OF THE SOLAR-X-RAY CORONA SO SOLAR PHYSICS LA English DT Article AB The first published three-dimensional images of the solar X-ray corona, obtained by means of solar rotational parallax, are presented in stereographic form. Image pairs approximately 12 hours apart during times of stable coronal conditions were selected from the digitized images obtained with the Skylab X-ray Spectrographic Telescope, The image resolution limit is approximately 10 are sec. Many coronal structures not visible in the separate images are clearly observed when the image pairs are viewed stereoscopically. This method gives a preview of the potential resources for solar research and forecasting of solar-geomagnetic interactions that could be provided by stereoscopic observations of the Sun using a small group of spacecraft. The method is also applicable to other X-ray, ultraviolet, or other wavebands in which the corona has extended, transparent structure. RP BATCHELOR, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SPACE PHYS DATA FACIL,GREENBELT,MD 20771, USA. NR 7 TC 15 Z9 15 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 1994 VL 155 IS 1 BP 57 EP 61 DI 10.1007/BF00670730 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QF698 UT WOS:A1994QF69800004 ER PT J AU SNODDY, WC NEIN, ME HILCHEY, JD AF SNODDY, WC NEIN, ME HILCHEY, JD TI DESIGN CONSIDERATIONS AND STRATEGIES FOR LUNAR-BASED OBSERVATIONS SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article AB This paper addresses the design considerations and strategies for astrophysical observations as key elements of an international solar system exploration program. Emphasis is placed on the technical and programmatic challenges and opportunities associated with an evolving program of lunar-based astronomy. Both robotic and human tended facilities are discussed ranging from relatively small meter-class transit telescopes to large interferometer and filled-aperture systems. RP SNODDY, WC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,PROGRAM DEV DIRECTORATE,HUNTSVILLE,AL 35812, USA. NR 0 TC 0 Z9 0 U1 0 U2 2 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 NOV PY 1994 VL 14 IS 6 BP 355 EP 365 PG 11 WC Engineering, Aerospace SC Engineering GA RD938 UT WOS:A1994RD93800002 ER PT J AU CEREMUGA, J BARTON, M MIRANDA, F AF CEREMUGA, J BARTON, M MIRANDA, F TI ANALYSIS OF INFLUENCE OF BUFFER LAYERS ON MICROWAVE PROPAGATION THROUGH HIGH-TEMPERATURE SUPERCONDUCTING THIN-FILMS SO SUPERCONDUCTOR SCIENCE & TECHNOLOGY LA English DT Article ID SILICON-ON-SAPPHIRE; YBA2CU3O7-X; TRANSMISSION AB Methods of analysis of microwave propagation through superconducting thin films with buffer layers on dielectric substrates have been discussed. Expressions describing the transmission coefficient S-21 through the structure and the complex conductivity sigma of a superconductor in an analytical form have been derived. The derived equations are valid for microwave propagation in waveguides as well as in free space with relevant definition of impedances. Using the obtained solutions, the influences of buffer layers' parameters (thickness, relative permittivity and loss tangent) on the transmission coefficient has been investigated using MATLAB. Simulations have been performed for 10 GHz transmission through YBa2Cu3O7 films on sapphire with SrTiO3 and CeO2 buffer layers and on silicon with CaF2 and YSZ buffer layers. To illustrate the simulations, measurements of the transmission through YBCO film on sapphire with SrTiO3 buffer layer have been performed. It has been shown that even lossy buffer layers have very little impact (smaller than 1% in magnitude and 0.3% in phase) on the transmission coefficient through superconducting thin films, providing their thickness is below 10 mu m. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP JAMES COOK UNIV N QUEENSLAND, DEPT ELECT & COMP ENGN, TOWNSVILLE, QLD 4811, AUSTRALIA. NR 20 TC 8 Z9 8 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0953-2048 EI 1361-6668 J9 SUPERCOND SCI TECH JI Supercond. Sci. Technol. PD NOV PY 1994 VL 7 IS 11 BP 855 EP 867 DI 10.1088/0953-2048/7/11/014 PG 13 WC Physics, Applied; Physics, Condensed Matter SC Physics GA PT064 UT WOS:A1994PT06400014 ER PT J AU MYERS, DD AF MYERS, DD TI OUR FUTURE IN-SPACE SO TECHNOLOGY REVIEW LA English DT Letter RP MYERS, DD (reprint author), NASA,LEUCADIA,CA, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU MASS INST TECHNOL PI CAMBRIDGE PA CAMBRIDGE, MA 02139 SN 0040-1692 J9 TECHNOL REV JI Technol. Rev. PD NOV-DEC PY 1994 VL 97 IS 8 BP 7 EP 7 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PP073 UT WOS:A1994PP07300005 ER PT J AU PERRONE, JA STONE, LS AF PERRONE, JA STONE, LS TI A MODEL OF SELF-MOTION ESTIMATION WITHIN PRIMATE EXTRASTRIATE VISUAL-CORTEX SO VISION RESEARCH LA English DT Review DE OPTIC FLOW; HEADING PERCEPTION; DEPTH PERCEPTION; STABILITY OF GAZE; MT; MST; VESTIBULAR-OCULAR REFLEX ID PURSUIT EYE-MOVEMENTS; CORTICAL AREAS MT; OCULAR-FOLLOWING RESPONSES; SUPERIOR TEMPORAL SULCUS; MONKEY STRIATE CORTEX; OPTIC FLOW STIMULI; LINEAR HEAD MOTION; MACAQUE MONKEY; FUNCTIONAL-PROPERTIES; VIEWING DISTANCE AB Perrone [(1992) Journal of the Optical Society of America A, 9, 177-194] recently proposed a template-based model of self-motion estimation which uses direction- and speed-tuned input sensors similar to neurons in area MT of primate visual cortex. Such an approach would generally require an unrealistically large number of templates (five continuous dimensions). However, because primates, including humans, have a number of oculomotor mechanisms which stabilize gaze during locomotion, we can greatly reduce the number of templates required (two continuous dimensions and one compressed and bounded dimension). We therefore refined the model to deal with the gaze-stabilization case and extended it to extract heading and relative depth simultaneously. The new model is consistent with previous human psychophysics and has the emergent property that its output detectors have similar response properties to neurons in area MST. C1 STANFORD UNIV,DEPT PSYCHOL,STANFORD,CA 94305. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 141 TC 164 Z9 166 U1 2 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0042-6989 J9 VISION RES JI Vision Res. PD NOV PY 1994 VL 34 IS 21 BP 2917 EP 2938 DI 10.1016/0042-6989(94)90060-4 PG 22 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA PJ389 UT WOS:A1994PJ38900013 PM 7975326 ER PT J AU FREEDMAN, WL MADORE, BF MOULD, JR HILL, R FERRARESE, L KENNICUTT, RC SAHA, A STETSON, PB GRAHAM, JA FORD, H HOESSEL, JG HUCHRA, J HUGHES, SM ILLINGWORTH, GD AF FREEDMAN, WL MADORE, BF MOULD, JR HILL, R FERRARESE, L KENNICUTT, RC SAHA, A STETSON, PB GRAHAM, JA FORD, H HOESSEL, JG HUCHRA, J HUGHES, SM ILLINGWORTH, GD TI DISTANCE TO THE VIRGO CLUSTER GALAXY M100 FROM HUBBLE-SPACE-TELESCOPE OBSERVATIONS OF CEPHEIDS SO NATURE LA English DT Article ID MEASURING EXTRAGALACTIC DISTANCES; RR LYRAE STARS; ABSOLUTE MAGNITUDES; STANDARD CANDLES; IA SUPERNOVAE; SCALE; CONSTANT; MOTION; VELOCITY; SUPERCLUSTER AB Accurate distances to galaxies are critical for determining the present expansion rate of the Universe or Hubble constant (H-o). An important step in resolving the current uncertainty in H-o is the measurement of the distance to the Virgo cluster of galaxies. New observations using the Hubble Space Telescope yield a distance of 17.1 +/- 1.8 Mpc to the Virgo cluster galaxy M100. This distance leads to a value of H-o = 80 +/- 17 km s(-1) Mpc(-1). A comparable value of H-o is also derived from the Coma cluster using independent estimates of its distance ratio relative to the Virgo cluster. C1 CALTECH, JET PROP LAB, CTR INFRARED PROC & ANAL, NASA IPAC EXTRAGALACT DATABASE, PASADENA, CA 91125 USA. AUSTRALIAN NATL UNIV, MT STROMLO & SIDING SPRING OBSERV, WESTON, ACT 2611, AUSTRALIA. JOHNS HOPKINS UNIV, DEPT PHYS & ASTRON, BALTIMORE, MD 21218 USA. UNIV ARIZONA, STEWARD OBSERV, TUCSON, AZ 85721 USA. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. DOMINION ASTROPHYS OBSERV, VICTORIA V8X 4M6, BC, CANADA. CARNEGIE INST WASHINGTON, DEPT TERR MAGNETISM, WASHINGTON, DC 20015 USA. UNIV WISCONSIN, DEPT ASTRON, MADISON, WI 53706 USA. HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. ROYAL GREENWICH OBSERV, CAMBRIDGE CB3 0HA, ENGLAND. UNIV CALIF SANTA CRUZ, LICK OBSERV, SANTA CRUZ, CA 95064 USA. RP FREEDMAN, WL (reprint author), CARNEGIE INST WASHINGTON OBSERV, 813 SANTA BARBARA ST, PASADENA, CA 91101 USA. NR 51 TC 389 Z9 390 U1 1 U2 7 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 27 PY 1994 VL 371 IS 6500 BP 757 EP 762 DI 10.1038/371757a0 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PP018 UT WOS:A1994PP01800048 ER PT J AU CAMPBELL, BA AF CAMPBELL, BA TI BELL REGIO, VENUS - INTEGRATION OF REMOTE-SENSING DATA AND TERRESTRIAL ANALOGS FOR GEOLOGIC ANALYSIS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MAGELLAN OBSERVATIONS; RADAR DATA; SURFACE; FEATURES; TOPOGRAPHY AB The geology and surface morphology of Bell Regio (18-42-degrees-N, 32-58-degrees-E) are investigated using a combination of Magellan, Venera, and analogous terrestrial data. The properties of surface units are compared to either direct terrestrial analog measurements or to the behaviors predicted by theoretical models. Five major volcanic sources are identified from geologic mapping (Tepev Mons, Nefertiti corona, a large shield volcano east of Tepev, and two small edifices southest of Tepev). The volcano Api Mons lies northeast of the main Bell uplift. The oldest volcanic units are associated with an extensive low shield volcano east of Tepev Mons and a small edifice southeast of Tepev. The annular flow apron of Tepev Mons formed next, with volcanism at a second small edifice on the southeast flank of Tepev Mons producing the youngest flow units. Comparisons between Magellan data, terrestrial radar images, and field topography profiles suggest that only three units resemble terrestrial a'a flows; the remainder are consistent with smoother pahoehoe-type surfaces. This suggests that most of the flow units were erupted at relatively low volume effusion rates (<100 m3/s) over long periods of time or had very low viscosities. One flow unit has a knobby texture which resembles large tumuli or ridge structures. Much of the tectonic deformation in the area is in the form of fractures circumferential to the edifices and isolated blocks of tessera terrain; there are no rift zones such as those which occur at Beta Regio, Atla Regio, or Western Eistla Regio. Tepev Mons is characterized by very steep slopes (up to 40-degrees along the east flank), a relatively flat summit, and two large (11 and 31 km) calderas. Though covered in places by high-dielectric material, the Tepev Mons summit area is relatively smooth with the exception of annular rough deposits which ring the two calderas. These calderas are quite shallow (on the order of a few hundred meters at most), with no discernible difference in radius between individual altimeter footprints inside and outside the larger eastern feature. Magellan and Venera data suggest that the eastern caldera is covered by a layer of unconsolidated material. Ejecta from Miriam crater has produced a halo with a dielectric constant of 6-7 surrounding Nefertiti corona, and Potanina crater ejecta is the likely source material for radar-dark wind streaks south of Tepev Mons. A low-dielectric (epsilon=2-3) triangular region on the south flank of Tepev Mons may be a pyroclastic or crater ejecta deposit which has been spread westward by the wind. This region has undergone a wide variety of volcanic processes, with a major shift in eruptive style from the older low-relief eastern volcanic center to the steep slopes and large summit calderas characteristic of Tepev Mons and the two smaller edifices. C1 NASA,DIV SOLAR SYST EXPLORAT,WASHINGTON,DC 20546. RP CAMPBELL, BA (reprint author), NATL AIR & SPACE MUSEUM,CTR EARTH & PLANETARY STUDIES,WASHINGTON,DC 20560, USA. NR 30 TC 26 Z9 26 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 1994 VL 99 IS E10 BP 21153 EP 21171 DI 10.1029/94JE01862 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PN669 UT WOS:A1994PN66900004 ER PT J AU KIM, YJ BUSCH, R JOHNSON, WL RULISON, AJ RHIM, WK AF KIM, YJ BUSCH, R JOHNSON, WL RULISON, AJ RHIM, WK TI METALLIC-GLASS FORMATION IN HIGHLY UNDERCOOLED ZR41.2TI13.8CU12.5NI10.0BE22.5 DURING CONTAINERLESS ELECTROSTATIC LEVITATION PROCESSING SO APPLIED PHYSICS LETTERS LA English DT Article AB Various sample sizes of Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 with masses up to 80 mg were undercooled below T-g (the glass transition temperature) while electrostatically levitated. The final solidification product of the sample was determined by x-ray diffraction to have an amorphous phase. Differential scanning calorimetry was used to confirm the absence of crystallinity in the processes sample. The amorphous phase could be formed only after heating the samples above the melting temperature for extended periods of time in order to break down and dissolve oxides or other contaminants which would otherwise initiate heterogeneous nucleation of crystals. Noncontact pyrometry was used to monitor the sample temperature throughout processing. The critical cooling rate required to avoid crystallization during solidification of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy fell between 0.9 and 1.2 K/s. (C) 1994 American Institute of Physics. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP KIM, YJ (reprint author), CALTECH,WM KECK LAB ENGN MAT 138-78,PASADENA,CA 91125, USA. NR 12 TC 147 Z9 150 U1 0 U2 18 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 24 PY 1994 VL 65 IS 17 BP 2136 EP 2138 DI 10.1063/1.112768 PG 3 WC Physics, Applied SC Physics GA PN176 UT WOS:A1994PN17600006 ER PT J AU JONES, L AKI, K BOORE, D CELEBI, M DONNELLAN, A HALL, J HARRIS, R HAUKSSON, E HEATON, T HOUGH, S HUDNUT, K HUTTON, K JOHNSTON, M JOYNER, W KANAMORI, H MARSHALL, G MICHAEL, A MORI, J MURRAY, M PONTI, D REASENBERG, P SCHWARTZ, D SEEBER, L SHAKAL, A SIMPSON, R THIO, H TINSLEY, J TODOROVSKA, M TRIFUNAC, M WALD, D ZOBACK, ML AF JONES, L AKI, K BOORE, D CELEBI, M DONNELLAN, A HALL, J HARRIS, R HAUKSSON, E HEATON, T HOUGH, S HUDNUT, K HUTTON, K JOHNSTON, M JOYNER, W KANAMORI, H MARSHALL, G MICHAEL, A MORI, J MURRAY, M PONTI, D REASENBERG, P SCHWARTZ, D SEEBER, L SHAKAL, A SIMPSON, R THIO, H TINSLEY, J TODOROVSKA, M TRIFUNAC, M WALD, D ZOBACK, ML TI THE MAGNITUDE-6.7 NORTHRIDGE, CALIFORNIA, EARTHQUAKE OF 17-JANUARY-1994 SO SCIENCE LA English DT Article ID STRONG GROUND MOTION; 1971 SAN-FERNANDO; WHITTIER-NARROWS EARTHQUAKE; BOORE ATTENUATION DATA; SOUTHERN-CALIFORNIA; VENTURA BASIN; ANDREAS FAULT; LOS-ANGELES; SEISMICITY; VALLEY AB The most costly American earthquake since 1906 struck Los Angeles on 17 January 1994. The magnitude 6.7 Northridge earthquake resulted from more than 3 meters of reverse slip on a 15-kilometer-long south-dipping thrust fault that raised the Santa Susana mountains by as much as 70 centimeters. The fault appears to be truncated by the fault that broke in the 1971 San Fernando earthquake at a depth of 8 kilometers. Of these two events, the Northridge earthquake caused many times more damage, primarily because its causative fault is directly under the city. Many types of structures were damaged, but the fracture of welds in steel-frame buildings was the greatest surprise. The Northridge earthquake emphasizes the hazard posed to Los Angeles by concealed thrust faults and the potential for strong ground shaking in moderate earthquakes. C1 UNIV SO CALIF, DEPT GEOL, LOS ANGELES, CA 90089 USA. CALTECH, JET PROP LAB, PASADENA, CA 91125 USA. UNIV CALIF SAN DIEGO, SAN DIEGO, CA 92103 USA. CALIF DIV MINES & GEOL, PLEASANT HILL, CA USA. COLUMBIA UNIV, NEW YORK, NY 10027 USA. RP US GEOL SURVEY, 525 S WILSON AVE, PASADENA, CA 91106 USA. RI Hudnut, Kenneth/B-1945-2009; Hudnut, Kenneth/G-5713-2010; Michael, Andrew/A-5059-2010; Harris, Ruth/C-4184-2013; OI Hudnut, Kenneth/0000-0002-3168-4797; Michael, Andrew/0000-0002-2403-5019; Harris, Ruth/0000-0002-9247-0768; Hauksson, Egill/0000-0002-6834-5051; Wald, David/0000-0002-1454-4514 NR 54 TC 81 Z9 82 U1 2 U2 11 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 EI 1095-9203 J9 SCIENCE JI Science PD OCT 21 PY 1994 VL 266 IS 5184 BP 389 EP 397 PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PN272 UT WOS:A1994PN27200023 ER PT J AU WENNBERG, PO COHEN, RC STIMPFLE, RM KOPLOW, JP ANDERSON, JG SALAWITCH, RJ FAHEY, DW WOODBRIDGE, EL KEIM, ER GAO, RS WEBSTER, CR MAY, RD TOOHEY, DW AVALLONE, LM PROFFITT, MH LOEWENSTEIN, M PODOLSKE, JR CHAN, KR WOFSY, SC AF WENNBERG, PO COHEN, RC STIMPFLE, RM KOPLOW, JP ANDERSON, JG SALAWITCH, RJ FAHEY, DW WOODBRIDGE, EL KEIM, ER GAO, RS WEBSTER, CR MAY, RD TOOHEY, DW AVALLONE, LM PROFFITT, MH LOEWENSTEIN, M PODOLSKE, JR CHAN, KR WOFSY, SC TI REMOVAL OF STRATOSPHERIC O-3 BY RADICALS - IN-SITU MEASUREMENTS OF OH, HO2, NO, NO2, CLO, AND BRO SO SCIENCE LA English DT Article ID INSITU MEASUREMENTS; OZONE DEPLETION; PHOTOLYSIS; CHEMISTRY; NITROGEN AB Simultaneous in situ measurements of the concentrations of OH, HO2, ClO, BrO, NO, and NO2 demonstrate the predominance of odd-hydrogen and halogen free-radical catalysis in determining the rate of removal of ozone in the lower stratosphere during May 1993. A single catalytic cycle, in which the rate-limiting step is the reaction of HO2 with ozone, accounted for nearly one-half of the total O-3 removal in this region of the atmosphere. Halogen-radical chemistry was responsible for approximately one-third of the photochemical removal of O-3; reactions involving BrO account for one-half of this loss. Catalytic destruction by NO2, which for two decades was considered to be the predominant loss process, accounted for less than 20 percent of the 0(3) removal. The measurements demonstrate quantitatively the coupling that exists between the radical families. The concentrations of HO2 and ClO are inversely correlated with those of NO and NO2. The direct determination of the relative importance of the catalytic loss processes, combined with a demonstration of the reactions linking the hydrogen, halogen, and nitrogen radical concentrations, shows that in the air sampled the rate of O-3 removal was inversely correlated with total NOx loading. C1 HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. NOAA,AERON LAB,BOULDER,CO 80303. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV CALIF IRVINE,IRVINE,CA 92717. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP WENNBERG, PO (reprint author), HARVARD UNIV,DEPT CHEM,12 OXFORD ST,CAMBRIDGE,MA 02138, USA. RI Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013; Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Toohey, Darin/A-4267-2008; Wennberg, Paul/A-5460-2012 OI Fahey, David/0000-0003-1720-0634; Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; Toohey, Darin/0000-0003-2853-1068; NR 31 TC 291 Z9 292 U1 3 U2 42 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 21 PY 1994 VL 266 IS 5184 BP 398 EP 404 DI 10.1126/science.266.5184.398 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PN272 UT WOS:A1994PN27200024 PM 17816682 ER PT J AU SMITH, GL AF SMITH, GL TI EFFECTS OF TIME RESPONSE ON THE POINT-SPREAD FUNCTION OF A SCANNING RADIOMETER SO APPLIED OPTICS LA English DT Article AB Scanning radiometers on satellites have a finite response time, because of the detector and the associated electronics. The radiometer measurement as it scans over a point source of radiation of unit strength is the point spread function (PSF). The time response causes a widening and skewing of the PSF. The PSF of a scanning radiometer that has well-focused optics together with time responses for the detector and electronic filter is treated in the time domain. The PSF can be expressed in terms of the system time response to a step input. For a first-order system time response, the displacement of the centroid is the product of the system time constant and the scan rate of the radiometer. The electronic filter further displaces the centroid of the PSF by the product of the scan rate and the filter time constant. Also, the width of the PSF in the scan direction will be increased because of the system time response. The minimum resolvable feature is of the order of the width of the PSF, thus the system time response limits the resolution in the scan direction that can be obtained. The analysis is illustrated by applying it to the Clouds and Earth Radiant Energy System experiment scanning radiometer. RP SMITH, GL (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MS-420, HAMPTON, VA 23665 USA. NR 11 TC 45 Z9 45 U1 1 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD OCT 20 PY 1994 VL 33 IS 30 BP 7031 EP 7037 PG 7 WC Optics SC Optics GA PN179 UT WOS:A1994PN17900019 PM 20941254 ER PT J AU MIISHCHENKO, MI TRAVIS, LD AF MIISHCHENKO, MI TRAVIS, LD TI LIGHT-SCATTERING BY POLYDISPERSIONS OF RANDOMLY ORIENTED SPHEROIDS WITH SIZES COMPARABLE TO WAVELENGTHS OF OBSERVATION SO APPLIED OPTICS LA English DT Article DE LIGHT SCATTERING; NONSPHERICAL PARTICLES; AEROSOLS; REMOTE SENSING ID NONSPHERICAL TSCHEBYSCHEFF PARTICLES; AXIALLY-SYMMETRICAL PARTICLES; ELECTROMAGNETIC SCATTERING; TROPOSPHERIC AEROSOLS; POLARIZED-LIGHT; PLANETARY-ATMOSPHERES; SHAPE DISTRIBUTIONS; SINGLE-SCATTERING; MATRIX; DEPOLARIZATION AB We report the results of an extensive study of the scattering of light by size and size-shape distributions of randomly oriented prolate and oblate spheroids with the index of refraction 1.5 + 0.02i typical of some mineral terrestrial aerosols. The scattering calculations have been carried out with Waterman's T-matrix approach, as developed recently by Mishchenko [J. Opt. Soc. Am. A 8, 871 (1991); Appl. Opt. 32, 4562 (1993)]. Our main interest is in light scattering by polydisperse models of nonspherical particles because averaging over sizes provides more realistic modeling of natural ensembles of scattering particles and washes out the interference structure and ripple typical of monodisperse scattering patterns, thus enabling us to derive meaningful conclusions about the effects of particle nonsphericity on light scattering. Following Hansen and Travis [Space Sci. Rev. 16, 527 (1974)], we show that scattering properties of most physically plausible size distributions of randomly oriented nonspherical particles depend primarily on the effective equivalent-sphere radius and effective variance of the distribution, the actual shape of the distribution having a minor influence. To minimize the computational burden, we have adopted a computationally convenient power law distribution of particle equivalent-sphere radii n(r) is-proportional-to r-3, r1 less-than-or-equal-to r less-than-or-equal-to r2. The effective variance of the size distribution is fixed at 0.1, and the effective size parameter continuously varies from 0 to 15. We present results of computer calculations for 24 prolate and oblate spheroidal shapes with aspect ratios from 1.1 to 2.2. The elements of the scattering matrix for the whole range of size parameters and scattering angles are displayed in the form of contour plots. Computational results are compared with analogous calculations for surface-equivalent spheres, and the effects of particle shape on light scattering are discussed in detail. RP MIISHCHENKO, MI (reprint author), HUGHES STX CORP, NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Mishchenko, Michael/D-4426-2012 NR 65 TC 145 Z9 146 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD OCT 20 PY 1994 VL 33 IS 30 BP 7206 EP 7225 PG 20 WC Optics SC Optics GA PN179 UT WOS:A1994PN17900041 PM 20941276 ER PT J AU MIYAJI, T LAHAV, O JAHODA, K BOLDT, E AF MIYAJI, T LAHAV, O JAHODA, K BOLDT, E TI THE COSMIC X-RAY-BACKGROUND - IRAS GALAXY CORRELATION AND THE LOCAL X-RAY VOLUME EMISSIVITY SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY, THEORY; INFRARED, GALAXIES; RADIO CONTINUUM, GALAXIES; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; N-LOG S; REDSHIFT SURVEY; ANGULAR-CORRELATIONS; LUMINOSITY FUNCTIONS; NEARBY GALAXIES; SAMPLE; DENSITY; GRAVITY; ORIGIN AB We have cross-correlated the galaxies from the IRAS 2 Jy redshift survey sample and the 0.7 Jy projected sample with the all-sky cosmic X-ray background (CXB) map obtained from the HEAO 1 A-2 experiment. We have detected a significant correlation signal between surface density of IRAS galaxies and the X-ray background intensity, with W(xg) = {deltaIdeltaN}/{I}{N} of several times 10(-3). While this correlation signal has a significant implication for the contribution of the local universe to the hard (E > 2 keV) X-ray background, its interpretation is model-dependent. We have developed a formulation to model the cross-correlation between CXB surface brightness and galaxy counts. This includes the effects of source clustering and the X-ray-far-infrared luminosity correlation. Using an X-ray flux-limited sample of AGNs, which has IRAS 60 mum measurements, we have estimated the contribution of the AGN component to the observed CXB-IRAS galaxy count correlations in order to see whether there is an excess component, i.e., contribution from low X-ray luminosity sources. We have applied both the analytical approach and Monte Carlo simulations for the estimations. Our estimate of the local X-ray volume emissivity in the 2-10 keV band is rho(x) almost-equal-to (4.3 +/- 1.2) x 10(38) h50 ergs s-1 Mpc-3, consistent with the value expected from the luminosity function of AGNs alone. This sets a limit to the local volume emissivity from lower luminosity sources (e.g., star-forming galaxies, LINERs) to rho(x) less-than-or-similar-to 2 X 10(38) h50 ergs s-1 Mpc-3. C1 INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. RP MIYAJI, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,CODE 666,GREENBELT,MD 20771, USA. RI Jahoda, Keith/D-5616-2012 NR 44 TC 38 Z9 37 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 1994 VL 434 IS 2 BP 424 EP 434 DI 10.1086/174744 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700004 ER PT J AU SCHLEGEL, EM AF SCHLEGEL, EM TI A ROSAT OBSERVATION OF THE NEARBY SPIRAL GALAXY NGC-6946 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC 6946); GALAXIES, NUCLEI; GALAXIES, SPIRAL; X-RAY, GALAXIES ID X-RAY OBSERVATIONS; HOT INTERSTELLAR-MEDIUM; LARGE MAGELLANIC CLOUD; RADIO-CONTINUUM; NGC 6946; MAGNETIC-FIELDS; STAR FORMATION; IONIZED-GAS; EMISSION; IC-342 AB I present the ROSAT Position-Sensitive Proportional Counter image of the nearby, nearly face-on, spiral galaxy NGC 6946. The galaxy was observed with Einstein in 1980, uncovering a nuclear source, a source on or near the northern spiral arm, SN 1980K, and evidence for non-point-source (i.e., diffuse) emission. The ROSAT image resolves the nuclear region into approximately three sources, yields an accurate position for the north arm source, and reveals diffuse extended emission across the galaxy face, tracing at least the bright northern spiral arm of the galaxy. The diffuse emission is almost certainly the very hot component of the galaxy's interstellar medium and is probably similar to that found in the Milky Way and the Large Magellanic Cloud. RP SCHLEGEL, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 668,GREENBELT,MD 20771, USA. NR 47 TC 33 Z9 33 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 1994 VL 434 IS 2 BP 523 EP 535 DI 10.1086/174754 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700014 ER PT J AU FICHTEL, CE BERTSCH, DL DINGUS, BL ESPOSITO, JA HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MCDONALD, L MICHELSON, PF VONMONTIGNY, C NOLAN, PL SCHNEID, EJ SREEKUMAR, P THOMPSON, DJ AF FICHTEL, CE BERTSCH, DL DINGUS, BL ESPOSITO, JA HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MCDONALD, L MICHELSON, PF VONMONTIGNY, C NOLAN, PL SCHNEID, EJ SREEKUMAR, P THOMPSON, DJ TI SEARCH OF THE ENERGETIC GAMMA-RAY EXPERIMENT TELESCOPE (EGRET) DATA FOR HIGH-ENERGY GAMMA-RAY MICROSECOND BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE BLACK HOLE PHYSICS; GAMMA RAYS, BURSTS ID PRIMORDIAL BLACK-HOLES; OBJECTS; MASS AB Hawking (1974) and Page & Hawking (1976) investigated theoretically the possibility of detecting high-energy gamma rays produced by the quantum-mechanical decay of a small black hole created in the early universe. They concluded that, at the very end of the life of the small black hole, it would radiate a burst of gamma rays peaked near 250 MeV with a total energy of about 10(34) ergs in the order of a microsecond or less. The characteristics of a black hole are determined by laws of physics beyond the range of current particle accelerators; hence, the search for these short bursts of high-energy gamma rays provides at least the possibility of being the first test of this region of physics. The Compton Observatory EGRET has the capability of detecting directly the gamma rays from such bursts at a much fainter level than SAS 2, and a search of the EGRET data has led to an upper limit of 5 x 10(-2) black hole decays per pc3 yr-1, placing constraints on this and other theories predicting microsecond high-energy gamma-ray bursts. C1 NASA,GODDARD SPACE FLIGHT CTR,GFSC,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. STANFORD UNIV,WW HANSE EXPTL PHYS LAB,STANFORD,CA 94305. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,CTR COMPTON OBSERV SCI SUPPORT,GREENBELT,MD 20771. RP FICHTEL, CE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; OI Thompson, David/0000-0001-5217-9135; Dingus, Brenda/0000-0001-8451-7450 NR 15 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 1994 VL 434 IS 2 BP 557 EP 559 DI 10.1086/174758 PN 1 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700018 ER PT J AU BAND, DL FORD, LA MATTESON, JL BRIGGS, M PACIESAS, W PENDLETON, G PREECE, R PALMER, D TEEGARDEN, B SCHAEFER, B AF BAND, DL FORD, LA MATTESON, JL BRIGGS, M PACIESAS, W PENDLETON, G PREECE, R PALMER, D TEEGARDEN, B SCHAEFER, B TI BATSE GAMMA-RAY BURST LINE SEARCH .2. BAYESIAN CONSISTENCY METHODOLOGY SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS; METHODS, STATISTICAL ID CYCLOTRON; SPECTRA AB We describe a Bayesian methodology to evaluate the consistency between the reported Ginga and BATSE detections of absorption features in gamma-ray burst spectra. Currently no features have been detected by BATSE, but this methodology will still be applicable if and when such features are discovered. The Bayesian methodology permits the comparison of hypotheses regarding the two detectors' observations and makes explicit the subjective aspects of our analysis (e.g., the quantification of our confidence in detector performance). We also present non-Bayesian consistency statistics. Based on preliminary calculations of line detectability, we find that both the Bayesian and non-Bayesian techniques show that the BATSE and Ginga observations are consistent given our understanding of these detectors. C1 NASA,GSFC,GREENBELT,MD 20770. UNIV ALABAMA,HUNTSVILLE,AL 35899. RP BAND, DL (reprint author), UNIV CALIF SAN DIEGO,CASS,LA JOLLA,CA 92093, USA. OI Preece, Robert/0000-0003-1626-7335 NR 19 TC 15 Z9 17 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 20 PY 1994 VL 434 IS 2 BP 560 EP 569 DI 10.1086/174759 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700019 ER PT J AU TITARCHUK, L AF TITARCHUK, L TI GENERALIZED COMPTONIZATION MODELS AND APPLICATION TO THE RECENT HIGH-ENERGY OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, THEORY; PLASMAS; RADIATION MECHANISMS, NONTHERMAL; X-RAYS, STARS ID X-RAY-EMISSION; ACCRETION DISKS; CYGNUS X-1; SPECTRUM; RADIATION AB The theory of spectral formation in thermal X-ray sources, where the effects of Comptonization and Klein-Nishina corrections are important, is presented. Analytical expressions are obtained for the produced spectrum as a function of such input parameters as the plasma temperature, the optical depth of the plasma cloud and the injected soft photon spectrum. The analytical theory developed here takes into account the dependence of the scattering opacity on the photon energy. It is shown that the plasma temperature as well as the asymptotic rate of photon escape from the plasma cloud determine the shape of the upscattered hard tail in the emergent spectra, even in the case of very small optical depths. The escape distributions of photons are given for any optical depth of the plasma cloud and their asymptotic dependence for very small and large optical depths are examined. It is shown that this new generalized approach can fit spectra for a large variety of hard X-ray sources and determine the plasma temperature in the region of main energy release in Cyg X-1 and the Seyfert galaxy NGC 4151. RP TITARCHUK, L (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,GREENBELT,MD 20771, USA. NR 40 TC 543 Z9 544 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 20 PY 1994 VL 434 IS 2 BP 570 EP 586 DI 10.1086/174760 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700020 ER PT J AU BENNETT, CL FIXSEN, DJ HINSHAW, G MATHER, JC MOSELEY, SH WRIGHT, EL EPLEE, RE GALES, J HEWAGAMA, T ISAACMAN, RB SHAFER, RA TURPIE, K AF BENNETT, CL FIXSEN, DJ HINSHAW, G MATHER, JC MOSELEY, SH WRIGHT, EL EPLEE, RE GALES, J HEWAGAMA, T ISAACMAN, RB SHAFER, RA TURPIE, K TI MORPHOLOGY OF THE INTERSTELLAR COOLING LINES DETECTED BY COBE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, ATOMS; ISM, BUBBLES; ISM, GENERAL; ISM, MOLECULES; LINE, IDENTIFICATION; GALAXY, GENERAL ID BACKGROUND-EXPLORER COBE; CENTER MOLECULAR CLOUDS; GALACTIC-CENTER REGION; FINE-STRUCTURE LINES; 158 MICRON EMISSION; PHOTODISSOCIATION REGIONS; H-I; STAR FORMATION; GALAXY; TEMPERATURE AB The Far-Infrared Absolute Spectrophotometer (FIRAS) on the COBE satellite has conducted an unbiased survey of the far-infrared emission from our Galaxy. The first results of this survey were reported by Wright et al. (1991). We report the results of new analyses of this spectral survey, which includes emission lines from 158 mum C+, 122 and 205 mum N+, 370 and 609 mum C0, and CO J = 2-1 through J = 5-4. We report the morphological distribution along the Galactic plane (b = 0-degree) of the spectral line emission, and the high Galactic latitude intensities of the C+ and 205 mum N+ emission. In the Galactic plane the 205 mum line of N+ generally follows the 158 mum C+ line distribution, but the intensities scale as I(N+ 205 mum) infinity I(C+ 158 mum)1.5 toward the inner Galaxy. The high Galactic latitude intensity of the 158 mum fine-structure transition from C+ is I(C+ 158 mum) = (1.43 +/- 0.12) x 10(-6) csc \b\ ergs cm-2 s-1 sr-1 for \b\ > 15-degrees, and it decreases more rapidly than the far-infrared intensity with increasing Galactic latitude. C+ and neutral atomic hydrogen emission are closely correlated with a C+ cooling rate of (2.65 +/- 0.15) x 10(-26) ergs s-1 (H atom)-1. We conclude that this emission arises almost entirely from the cold neutral medium. The high Galactic latitude intensity of the 205 mum fine-structure transition from N+ is I(N+ 205 mum) = (4 +/- 1) x 10(-8) csc \b\ ergs cm-2 s-1 sr-1 arising entirely from the warm ionized medium. We estimate the total ionizing photon rate in the Galaxy to be phi = 3.5 x 10(53) ionizing photons per second, based on the 205 mum N+ transition. C1 NASA,GODDARD SPACE FLIGHT CTR,GEN SCI CORP,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,APPL RES CORP,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP BENNETT, CL (reprint author), GODDARD SPACE FLIGHT CTR,INFRARED ASTROPHYS BRANCH,CODE 685,GREENBELT,MD 20771, USA. RI Hewagama, T/C-8488-2012; Moseley, Harvey/D-5069-2012 NR 83 TC 155 Z9 155 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 1994 VL 434 IS 2 BP 587 EP 598 DI 10.1086/174761 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700021 ER PT J AU SHRADER, CR WAGNER, RM HJELLMING, RM HAN, XH STARRFIELD, SG AF SHRADER, CR WAGNER, RM HJELLMING, RM HAN, XH STARRFIELD, SG TI THE EARLY ULTRAVIOLET, OPTICAL, AND RADIO EVOLUTION OF THE SOFT-X-RAY TRANSIENT GRO J0422+32 SO ASTROPHYSICAL JOURNAL LA English DT Article DE NOVAE, CATACLYSMIC VARIABLES; RADIO CONTINUUM, STARS; ULTRAVIOLET, STARS; X-RAY BURSTS; X-RAYS, STARS ID NOVA-MUSCAE 1991; BLACK-HOLE; A0620-00 AB We have monitored the evolution of the transient X-ray source GRO J0422 + 32 from approximately 2 weeks postdiscovery into its early decline phase at ultraviolet, optical, and radio wavelengths. Optical and ultraviolet spectra exhibit numerous, but relatively weak, high-excitation emission lines such as those arising from He II, N III, N V, and C IV superposed on an intrinsically blue continuum. High-resolution optical spectroscopy reveals line profiles which are double peaked, and in the case of the higher order Balmer lines, superposed on a broad absorption profile. The early outburst optical-ultraviolet continuum energy distribution is well represented by a two power-law fit with a break at congruent-to 4000 angstrom. Radio observations with the VLA reveal a flat-spectrum source, slowly increasing in intensity at the earliest epochs observed, followed by an approximate power-law decay light curve with an index of - 1. Light curves for each wavelength domain are presented and discussed. Notable are the multiple secondary outbursts seen in the optical more than 1 year postdiscovery, and spectral changes associated with secondary rises seen in the radio and UV. We find that the ultraviolet and optical characteristics of GRO J0422 + 32 as well as its radio evolution, are similar to other recent well-observed soft X-ray transients (also called X-ray novae) such as Cen X-4, A0620-00 (V616 Mon), and Nova Muscae 1991 (GS 1124-683), suggesting that GRO J0422 + 32 is also a member of that subclass of low-mass X-ray binaries. We present definitive astrometric determination of the source position, and place an upper limit of R congruent-to 20 from our analysis of the POSS. Additionally, we derive distinct values for color excess from analysis of the optical [E(B - V) = 0.23] and ultraviolet [E(B - V) = 0.4] data, suggesting an intrinsic magnitude of 19-19.5 for the progenitor if it is mid-K dwarf. This leads to a likely range of 2.4-3.0 kpc for the source distance, which is consistent with our separate estimate of 2.4 +/- 0.4 kpc based on measurement of the NaD interstellar line profile. Adopting 2.4 kpc and E(B - V ) = 0.23, the outburst absolute magnitude was M congruent-to 0.0, which is a typical value for this class of objects. C1 OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. COMP SCI CORP,SCI PROGRAM,SEABROOK,MD 20706. LOWELL OBSERV,FLAGSTAFF,AZ 86001. RP SHRADER, CR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,CODE 6681,GREENBELT,MD 20771, USA. NR 41 TC 58 Z9 59 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 1994 VL 434 IS 2 BP 698 EP 706 DI 10.1086/174771 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700031 ER PT J AU LINNELL, AP HUBENY, I AF LINNELL, AP HUBENY, I TI A SPECTRUM SYNTHESIS PROGRAM FOR BINARY STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, ECLIPSING; METHODS, NUMERICAL; STARS, INDIVIDUAL (SX AURIGAE, EE PEGASI); TECHNIQUES, SPECTROSCOPIC ID ROTATING STARS; O-STAR; MASSES; LINES; ATMOSPHERES; ABUNDANCES AB A new program produces synthetic spectra of binary stars at arbitrary values of orbital longitude, including longitudes of partial or complete eclipse. The stellar components may be distorted, either tidally or rotationally, or both. Either or both components may be rotating nonsynchronously. We illustrate the program performance with two cases: EE Peg, an eclipsing binary with small distortion, and SX Aur, an eclipsing binary that is close to contact. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP LINNELL, AP (reprint author), MICHIGAN STATE UNIV,DEPT PHYS & ASTRON,E LANSING,MI 48824, USA. NR 39 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1994 VL 434 IS 2 BP 738 EP 746 DI 10.1086/174776 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700036 ER PT J AU SCHMELZ, JT HOLMAN, GD BROSIUS, JW WILLSON, RF AF SCHMELZ, JT HOLMAN, GD BROSIUS, JW WILLSON, RF TI CORONAL MAGNETIC-STRUCTURES OBSERVING CAMPAIGN .3. CORONAL PLASMA AND MAGNETIC-FIELD DIAGNOSTICS DERIVED FROM MULTIWAVEBAND ACTIVE-REGION OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE POLARIZATION; SUN, CORONA; SUN, MAGNETIC FIELDS; SUN, RADIO RADIATION ID FE-XVII; SOLAR; RATIOS; PLAGE AB Simultaneous soft X-ray, microwave, and photospheric magnetic field observations were taken during the Coronal Magnetic Structures Observing Campaign (CoMStOC '87). The plasma electron temperature and emission measures determined from the X-ray data are used to predict the free-free emission expected at 20 and 6 cm. Comparing these predictions with the microwave observations, it is found that the predicted 20 cm brightness temperatures are higher than the observed, requiring cool absorbing material between the hot X-ray plasma and the observer. The model that is most consistent with all the observations and minimizes the required coronal fields indicates that this 20 cm emission is either free-free or a combination of free-free and fourth harmonic cyclotron emanating from the X-ray plasma with an electron temperature of approximately 3.1 x 10(6) K and an emission measure of approximately 1.3 x 10(29) cm-5. The observed 20 cm polarization requires a field strength of greater-than-or-equal-to 150 G. In addition, the 6 cm emission is free-free, emanating from cooler plasma with an electron temperature of approximately 1.5 x 10(6) K and an emission measure of approximately 3-6 x 10(29) cm-5. This model is consistent with the rather unusual combination of high 20 cm and low 6 cm polarization as well as the low extrapolated coronal fields. C1 HUGHES STX,LANHAM,MD 20706. TUFTS UNIV,DEPT PHYS & ASTRON,MEDFORD,MA 02155. NASA,GODDARD SPACE FLIGHT CTR,LASP,GREENBELT,MD 20771. RP SCHMELZ, JT (reprint author), RHODES COLL,DEPT PHYS,2000 N PKWY,MEMPHIS,TN 38112, USA. RI Holman, Gordon/C-9548-2012 NR 27 TC 34 Z9 34 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 1994 VL 434 IS 2 BP 786 EP 794 DI 10.1086/174781 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700041 ER PT J AU JEFFERIES, SM OSAKI, Y SHIBAHASHI, H DUVALL, TL HARVEY, JW POMERANTZ, MA AF JEFFERIES, SM OSAKI, Y SHIBAHASHI, H DUVALL, TL HARVEY, JW POMERANTZ, MA TI USE OF ACOUSTIC-WAVE TRAVEL-TIME MEASUREMENTS TO PROBE THE NEAR-SURFACE LAYERS OF THE SUN SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, INTERIOR; SUN, OSCILLATIONS; WAVES ID HIGH-FREQUENCY; SOLAR OSCILLATIONS; MODES AB The variation of solar p-mode travel times with cyclic frequency v is shown to provide information on both the radial variation of the acoustic potential and the depth of the effective source of the oscillations. Observed travel-time data for waves with frequency lower than the acoustic cutoff frequency for the solar atmosphere (almost-equal-to 5.5 mHz) are inverted to yield the local acoustic cutoff frequency v(c) as a function of depth in the outer convection zone and lower atmosphere of the Sun. The data for waves with v > 5.5 mHz are used to show that the source of the p-mode oscillations lies approximately 100 km beneath the base of the photosphere. This depth is deeper than that determined using a standard mixing-length calculation. C1 NATL SOLAR OBSERV,NOAO,TUCSON,AZ 85719. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV TOKYO,SCH SCI,DEPT ASTRON,BUNKYO KU,TOKYO 113,JAPAN. RP JEFFERIES, SM (reprint author), UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716, USA. RI Duvall, Thomas/C-9998-2012 NR 25 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 1994 VL 434 IS 2 BP 795 EP 800 DI 10.1086/174782 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700042 ER PT J AU KEENAN, FP CONLON, ES RUBIN, RH AF KEENAN, FP CONLON, ES RUBIN, RH TI RELATIVE EMISSION-LINE STRENGTHS FOR THE 146 AND 63 MICRON TRANSITIONS IN O-I AND A COMPARISON WITH FAR-INFRARED OBSERVATIONS OF PHOTODISSOCIATION REGIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; H-II REGIONS; INFRARED, ISM, LINES AND BANDS ID FINE-STRUCTURE EXCITATION; ATOMIC OXYGEN; GAS; SPECTROMETER; ABUNDANCE; NEBULAE; STATES; RATIOS; IMPACT; SUN AB Theoretical O I density-sensitive emission-line ratios R = I(2s(2)2p4(3)P0-2s(2)2p4(3)P1)/I(2s(2)2p4(3)P1-2s(2)2p4(3)P2) = I(146 mum)/I(63 mum) are presented for a range of temperatures (T = 100-10,000 K), neutral hydrogen densities (N(H) = 10(-2) to 10(7) cm-3) and radiation fields (G0 = 1-10(6)) applicable to both photo-dissociation regions (PDRs) and H II regions and the diffuse ionized medium (DIM). The observed values of R for several PDRs, measured from far-infrared spectra obtained with the Kuiper Airborne Observatory, imply hydrogen densities which are in good agreement with those determined using other methods. This provides observational support for the validity of the theoretical O I line ratios, and hence the atomic data used in their derivation. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP KEENAN, FP (reprint author), QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. NR 28 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 OCT 20 PY 1994 VL 434 IS 2 BP 811 EP 815 DI 10.1086/174785 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PL837 UT WOS:A1994PL83700045 ER EF