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  • ENERGY PRODUCTION AND CONVERSION  (634)
  • ASTRONOMY  (384)
  • AERODYNAMICS  (366)
  • Adaptation
  • 1980-1984  (1,391)
  • 1975-1979
  • 1981  (1,391)
Collection
Keywords
Publisher
Years
  • 1980-1984  (1,391)
  • 1975-1979
Year
  • 1
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    Curved-flow, rolling-flow, and oscillatory pure-yawing wind-tunnel test methods for determination of dynamic stability derivatives (1981)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: The test capabilities of the Stability Wind Tunnel of the Virginia Polytechnic Institute and State University are described, and calibrations for curved and rolling flow techniques are given. Oscillatory snaking tests to determine pure yawing derivatives are considered. Representative aerodynamic data obtained for a current fighter configuration using the curved and rolling flow techniques are presented. The application of dynamic derivatives obtained in such tests to the analysis of airplane motions in general, and to high angle of attack flight conditions in particular, is discussed.
    Keywords: AERODYNAMICS
    Type: AGARD Dyn. Stability Parameters; 13 p
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  • 2
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    Spectroscopy in X-ray astronomy (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: Detailed features in cosmic X-ray sources and their associated temporal variation over a wide energy range were studied. Excess emission and absorption at approximately 6 to 7 kiloelectron volts in the spectra of supernova remnants, binary X-ray sources, and clusters of galaxies were observed. A gas scintillation proportional counter (GSPC) will be used as the detector system. In the gas scintillator the principal limitation is due to the statistics of the initial ionization process only.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 3
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    Far ultraviolet astronomy using the FAUST telescope (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The Far Ultraviolet Space Telescope (FAUST) a compact, wide field-of-view, far ultraviolet instrument designed for astronomical observations of extended and point sources is discussed. The design and application of the instrument are described. The prime objective is to observe faint astronomical sources with sensitivities higher than previously available. Scientific programs will include: (1) a search for ultraviolet stars which are predicted to exist at the stage of evolution prior to the final death of a star; (2) observations of galaxies and quasars; and (3) joint programs with other Spacelab 1 experiments. The secondary objective is to verify the suitability of the Spacelab as a platform for far ultraviolet astronomy: data will be provided on the ultraviolet background levels due to astronomical, terrestrial, and spacecraft generated sources; the levels of contaminants which affect ultraviolet instruments; and the capability of the Orbiter for stable pointing at celestial sources for useful periods of time.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 4
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    An analytic solution to the classical two-body problem with drag (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The two body problem was analyzed with a specific drag model. The model treats drag as a force proportional to the vector velocity and inversely proportional to the distance to the center of attraction. The solution is expressed in terms of known functions and is of a simple and compact form. The time of flight is expressed as a quadrature in the true anomaly. The results are: (1) development of a vector differential equation which allows analysis of an infinite number of gravitational and drag models; and (2) obtaining the solution of a linear differential equation using the inverse method of laplace transforms.
    Keywords: AERODYNAMICS
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 22 p
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  • 5
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    Langley high-lift research on a high-aspect-ratio supercritical wing configuration (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: To determine the low speed performance characteristics of a representative high aspect ratio supercritical wing, two low speed jet transport models were fabricated. A 12-ft. span model was used for low Reynolds number tests in the Langley 4- by 7-Meter Tunnel and the second, a 7.5-ft. span model, was used for high Reynolds number tests in the Ames 12-foot Pressure Tunnel. A brief summary of the results of the tests of these two models is presented and comparisons are made between the data obtained on these two models and other similar models. Follow-on two and three dimensional research efforts related to the EET high-lift configurations are also presented and discussed.
    Keywords: AERODYNAMICS
    Type: Advan. Aerodyn.: Selected NASA Res.; p 55-77
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  • 6
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    Measured transonic unsteady pressures on an energy efficient transport wing with oscillating control surfaces (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Highlight results are presented from subsonic and transonic pressure measurement studies conducted in the Langley Transonic Dynamics Tunnel on a supercritical wing model representative of an energy efficient transport design. Steady- and unsteady-pressure data were acquired on the upper and lower wing surface at an off-design Mach number of 0.60 and at the design Mach number of 0.78, for a Reynolds number of 2.2 x 10(6) (based on the wing average chord). The model configuration consisted of a sidewall-Mounted half-body fuselage and a semi-span wing with an aspect ratio of 10.76, a leading-edge sweepback angle of 28.8 degrees, and supercritical airfoil sections. The wing is instrumented with 252 static pressure orifices and 164 dynamic pressure gages. Model test variables included wing angle of attack, control-surface mean deflection angle, control-surface oscillating deflection angle and frequency, and phasing between oscillating leading-edge and trailing-edge controls when used together.
    Keywords: AERODYNAMICS
    Type: Advan. Aerodyn.: Selected NASA Res.; p 21-36
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  • 7
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    Comets (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The nature and origin of comets is discussed. Observations of the principal parts of comets, the dust and plasma tails, the hydrogen cloud, the coma and the cometary nucleus, are presented, and the icy conglomerate model of Whipple as extended by Delsemme accounting for the observed properties and their variation with heliocentric distance is examined. The origin of comets is considered in relation to the orbital statistics of the long-period comets and the existence of the Oort cloud on the edge of the solar system, and possible roles for comets in the solar nebula and the evolution of the solar system are indicated. Particular attention is then given to the discovery and properties of Halley's Comet, which is expected to reach perihelion in 1986, and to possible flyby and rendezvous missions to Halley's Comet and others.
    Keywords: ASTRONOMY
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  • 8
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    Electron densities for 10 planetary nebulae derived from the semiforbidden C III lambda 1907/1909 ratio. II (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Electron densities for IC 351, IC 2165, J900, IC 3568, NGC 6644, NGC 6891, IC 4997, NGC 7009, Hu 1-2, and IC 5217 are derived from high-dispersion semiforbidden C III spectrograms. For seven of these nebulae, the derived electron density is larger than the values derived from either surface brightness measurements or forbidden line ratios. Only one object, Hu 1-2, shows pronounced splitting of the semiforbidden C III emission lines due to a large expansion velocity.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 9
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    Medium energy gamma ray astronomy with transpacific balloon flights (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Transpacific balloon flights with the University of California, Riverside (UCR) double scatter telescope are discussed. With flight durations from 5 days up to perhaps 15 days the long observation times necessary for medium energy (1-30 MeV) gamma ray astronomy can be obtained. These flights would be made under the auspices of the Joint U.S.-Japan Balloon Flight Program at NASA. It is proposed that flights can provide at least 30 hours of observation time per flight for many discrete source candidates and 120 hours for detecting low intensity cosmic gamma ray bursts.
    Keywords: ASTRONOMY
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  • 10
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    Studies in astronomical time series analysis. I - Modeling random processes in the time domain (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Several random process models in the time domain are defined and discussed. Attention is given to the moving average model, the autoregressive model, and relationships between and combinations of these models. Consideration is then given to methods for investigating pulse structure, procedures of model construction, computational methods, and numerical experiments. A FORTRAN algorithm of time series analysis has been developed which is relatively stable numerically. Results of test cases are given to study the effect of adding noise and of different distributions for the pulse amplitudes. A preliminary analysis of the light curve of the quasar 3C 272 is considered as an example.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series; 45; Jan. 198
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  • 11
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    Three new 'nonterrestrial' molecules (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Eight new interstellar lines have been detected from three molecules not previously observed spectroscopically in space or in the laboratory. One is a linear or nearly linear molecule with microwave constants B0 equals 21,337.15 plus or minus 0.06 MHz, D0 equals 21.4 plus or minus 1.5 kHz. This is the thioformyl ion HCS(plus), first identified because B0 and D0 are close to those calculated, and now confirmed by laboratory detection of one of the present lines (Gudeman et al.). The second molecule, also linear or nearly so, has microwave constants B0 equals 10,691,406 plus or minus 0.043 MHz, D0 equals 1.84 plus or minus 0.91 kHz close to those expected for the isoelectronic systems HOCO(plus) and HOCN; a choice between the two cannot be made on the basis of the available astronomical data. The existence of a third molecule is deduced from an unidentified line at 85,338 MHz that has been found in many sources, is fairly intense in several, and may be self-absorbed in Sgr B2.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 12
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    Discovery of phase-locked variable polarization in an RS Canum Venaticorum-like star, HR 5110 (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Using measurements on 79 nights in 1980 January-August, it is established that the polarization in the ultraviolet (U band) varies synchronously on the known binary period of 2.6132 days, with a peak-to-peak amplitude of 0.03%. The pattern is mainly second harmonic in character, as typical of binary star examples such as Algol and Upsilon Her. Reflection by the cooler star, by a plasma concentration, or both, is suggested. The scale of the polarization seems to be consistent with Rayleigh scattering by neutral hydrogen on the cooler star, and a roughly lambda to the -4th wavelength dependence should be searched for. The QU curve suggests a sizeable inclination for the system, of about 45 deg, but this is preliminary. Separately, a possible weak periodicity might be present on a subsidiary period, conceivably related to a rotating star spot.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 13
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    Vortex-flow aerodynamics - An emerging design capability (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Promising current theoretical and simulational developments in the field of leading edge vortex-generating delta, arrow ogival wings are reported, along with the history of theory and experiment leading to them. The effects of wing slenderness, leading edge nose radius, Mach number and incidence variations, and planform on the onset of vortex generation and redistribution of aerodynamic loads are considered. The range of design possibilities in this field are consequential for the future development of strategic aircraft, supersonic transports and commercial cargo aircraft which will possess low-speed, high-lift capability by virtue of leading edge vortex generation and control without recourse to heavy and expensive leading edge high-lift devices and compound airfoils. Attention is given to interactive graphics simulation devices recently developed.
    Keywords: AERODYNAMICS
    Type: Astronautics and Aeronautics; 19; May 1981
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  • 14
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    The 45 micron H2O ice band in the Kleinmann-Low Nebula (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 245
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  • 15
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    Transport velocity transformation - A convenient method for performance analysis of multilayer solar cell structure (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is noted that in the case of low-level injection, space-charge quasi-neutrality, and spatially constant material parameters (including an electrostatic field), the individual layer can be treated analytically and the basic solar cell performance parameters can be evaluated from three equations. The first equation represents the transformation of the transport velocity across the layer from the other layer boundary. The second establishes the light-generated current output from the layer interface, under the influence of the transport velocities and minority-carrier density at both layer boundaries and of bulk recombination. The third equation describes the flow of these carriers across other layers. The power of the approach is considered to lie in its facility for analysis of the solar cell's performance layer by layer, giving a clear picture of the individual layer's influence on cell efficiency.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Transactions on Electron Devices; ED-28; May 1981
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  • 16
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    Longitudinal grooves for bluff body drag reduction (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Wind tunnel test results are presented for four axisymmetric bluff body configurations in order to determine their effect on form and pressure drag. It was found that drag reductions on the order of 40% are obtainable with an afterbody incorporating four longitudinal 'V' grooves. Although this effect may be due to the functioning of the grooves as longitudinal, continuous vortex generators, it is concluded that further research is needed to elucidate the physical basis of the test results. Optimization of the effect will be useful in base drag reduction for such vehicles as automobiles and cargo aircraft with sharply upswept afterbodies.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Apr. 198
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  • 17
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    Concerning the Wolf-Rayet and other luminous early-type stars (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Effective temperatures, radii, and luminosities were determined from S2/68, ANS, UBV, and uvby photometry for four B0/B1 supergiants, four O4 stars, and four WN7/WN8 stars as well as for four test stars having spectral types between B1.5 V and 09 V and five stars with known angular diameters and effective temperatures. The effective temperatures of B1 Ia+ stars are found to be near 17,000 K, those of O4 stars near 45,000, and those of WN7/WN8 stars near 26,000 K. The question of modeling the atmospheres of hot luminous stars is examined, and it is noted that the photosphere can be modeled adequately using a classical plane-parallel layer model atmosphere. In addition, it is found that the Wolf-Rayet stars of types WN7/WN8 fall in the H-R diagram near the B0 Ia stars, while the others fall near B0.5 III stars. The evolutionary relationship between the Wolf-Rayet and O stars is considered; it is suggested that a Wolf-Rayet spectrum is a short-lived phase in the life of a massive star.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 244
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  • 18
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    Observation of the core of the Perseus cluster with the Einstein solid state spectrometer - Cooling gas and elemental abundances (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Solid State Spectrometer observations of the core of the Perseus cluster have resulted in the detection of X-ray emission lines due to Si, S, and Fe. Analysis of the spectrum indicates that the X-ray emission has at least two characteristic temperatures. This is interpreted in the framework of radiative accretion in the core of the cluster. The derived parameters are a cooling time less than or approximately equal to 2 x 10 to the ninth years for the low-temperature gas, a mass accretion rate of approximately 300 solar masses per year, and a characteristic size of 10-20 kpc for the cool gas. The Fe abundance in the core (approximately 0.4) is similar to the Fe abundance averaged over the whole cluster, indicating that Fe emission is not strongly concentrated about NGC 1275. The Si and S abundances are consistent with solar values.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 244
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  • 19
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    Non-linear stability around the triangular libration points (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The configuration space around the triangular libration points in the Earth-Moon system is partitioned according to the stability of the motion. The regions around L4 and L5 are established where particles placed with zero initial velocity will librate. The complexity of the partitioning is revealed.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 23; Mar. 198
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  • 20
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    High-resolution observations of the QSO 3C 345 at 1.3 centimeters (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High-resolution VLBI observations made at a frequency of 22.235 GHz of the quasar 3C 345 are discussed. Antennas located at the Crimean Astrophysical Observatory, USSR; Onsala, Sweden; Effelsberg, West Germany; and the Haystack Observatory, Massachusetts were employed at 4-min integration times to provide baselines ranging up to 5.5 x 10 to the 8th wavelengths. About 40% of the total flux density of 7.85 Jy, observed in November 1977, and 8.05 Jy, observed in October 1978, is found to originate in an unresolved component of the quasar core in a region less than 0.1 milliarcsec in diameter. The elongated jet-like component of the quasar is observed to contain several peaks of emission extending up to 6 milliarsec from the core which decreased in extent between the two observations.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 243
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  • 21
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    Vectored injection into compressible laminar and turbulent boundary layers (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A fundamental analysis of two-dimensional supersonic boundary layer flow, both laminar and turbulent, is presented for a wide range of normal and nonnormal mass-transfer velocities. The analysis is based on the numerical solution of the Navier-Stokes equations, and results are compared with available theoretical and experimental data. Certain cases of practical importance, for which results are not presently available, are referred to.
    Keywords: AERODYNAMICS
    Type: Computer Methods in Applied Mechanics and Engineering; 25; Jan. 198
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  • 22
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    Report of the panel on theoretical aerodynamics (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Interactions between theoretical aerodynamics and the NTF are discussed. The development and validation of computational fluid dynamics computer codes, the determination of Reynolds number scaling laws, and extension of the data bases of entrainment type turbulence models to include high Reynolds number data are recommended areas of study. The major benefit theoretical aerodynamics could have on the NTF is in the quantitative description of wind tunnel wall interference effects.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 277-286
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  • 23
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    High Reynolds number research requirements for space vehicle design (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Requirements of entry vehicle design requiring high Reynolds number wind tunnel testing are discussed. The space shuttle orbiter, development of future space transportation systems, and planetary entry data analysis are considered.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 265-274
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  • 24
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    Report of the panel on aeroelasticity and unsteady aerodynamics (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The status of recommended areas of study for the NTF are reviewed. Transonic and control surface unsteady aerodynamics, and buffet onset and loads are considered. Testing of dynamically scaled flutter models is discussed.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 237-246
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  • 25
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    Model experience in the Langley 0.3-m transonic cryogenic tunnel (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The model building, development, and testing experience gained during 8 years of operation of the 0.3-m Transonic Cryogenic Tunnel (TCT) is summarized. The summary is divided into four portions: (1) models tested in the 0.3-m TCT's original octagonal test section; (2) models tested in the present two dimensional test section; (3) models tested as a part of tunnel calibration and the development of advanced technology airfoils; and (4) development of a new way to construct two dimensional airfoil models. Design requirements imposed on the models by high Reynolds number testing at cryogenic temperatures are reviewed.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 53-73
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  • 26
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    Radio astronomy (1981)
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    Publication Date: 2011-08-18
    Description: The activities of the Deep Space Network in support of radio astronomy operations during the first quarter of 1981 are reported. Results of the use of a low noise maser are presented, as well as updates in DSN support of experiments sanctioned by the Radio Astronomy Experiment Selection Panel.
    Keywords: ASTRONOMY
    Type: The Telecommun. and Data Acquisition Rept.; p 1-2
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  • 27
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    Solar cell measurements (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The measurement of the electrical performance characteristics of individual solar cells is discussed. One of the reasons is determination of the output power, measurement of the effect of various degradation mechanisms, and separation of cells by current and voltage for eventual use in series and parallel combinations. Major problem areas in making accurate performance measurements are the determination of the irradiance level during measurement, the measurement and control of cell junction temperature, and the contacting of the separate current and potential leads to the cell under test. Solar cells respond to only part of the solar spectrum, irradiance measurement made with blackbody detectors lead to spectral mismatch errors. The use of reference cells with a spectral response similar to that of the test cell reduces this error. Reference cells are calibrated at standard atmospheric conditions with all cells calibrated at the same conditions.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Midwest Research Inst. Com. Photovoltaics Meas. Workshop Proc.; p 227-233
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  • 28
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    High-resolution IUE observations of the 1981 eclipse of 32 CYG (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: 32 Cyg shows a spectacular pure emission line spectrum during eclipse. Six weeks later, most lines, which were observed in emission during eclipse, are seen as P Cygni type profiles with strong absorption components. The lines are formed through line scattering of B star light in the extended atmosphere (wind) of the K supergiant. During eclipse, the emission parts of the P Cyg lines remain visible since the size of the line scattering sphere around the B star is larger than the red giant. Other emission lines are formed in a shock front near the B star (CIV, SiIV, FeIII) and possibly in an accretion disk. The strong FeII UV Mult. 191 lambda lambda 1785-88 A is shown to be formed through optical pumping via FeII UV Mult. 9 photons. The phase dependence of the P Cyg type profiles is modelled by means of line transfer calculations in nonspherical, 3-dimensional geometry with velocity fields.
    Keywords: ASTRONOMY
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 245-259
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  • 29
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    Optical photometry of SS 433 - 200 nights of data 1979-1980 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Results from over 200 nights of optical photoelectric photometry of SS 433 during the period July 1979-October 1980 are presented. The data, taken in unfiltered light, the V band, an interference filter band centered on stationary H-alpha and a far-red band, provide evidence for an underlying 164-day light variation of peak-to-peak amplitudes 0.50 magnitude in V and 0.7 magnitude at 6567 A, and a binary-like variation with period 13.074 days and peak-to-peak amplitudes 0.50 and 0.60 magnitudes, respectively. The 13-day light curves are found to change slightly as a function of phase in the 164-day cycle, while seemingly erratic light fluctuations of up to 1 magnitude in 1 day and about 2 magnitudes in 3-4 days are imposed on both cyclic variations. It is noted that a conventional close-binary model is incapable of accounting for all the observed features, and alternatives involving some sort of luminous, rapidly changing extended low-mass envelope or screen in the binary system must be sought.
    Keywords: ASTRONOMY
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  • 30
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    Infrared photometry of comets Bowell and P/Stephan-Oterma (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Broadband IR photometry in the 1-20 micron range of the comets P/Stephan-Oterma and Bowell shows JHK colors similar to P/Meier and P/Tuttle, which are compatible with the scattering of sunlight by micron-sized grains. In addition, the P/Stephan-Oterma thermal emission was found to have an effective temperature higher than that expected from a blackbody in equilibrium. It is demonstrated that the thermal emission can be fit by models of the dust coma consisting of micron-sized grains, and that most of the flux at all observed wavelengths comes from the dust grains rather than the nucleus.
    Keywords: ASTRONOMY
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  • 31
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    X-ray and VLBI radio observations of the quasars NRAO 140 and NRAO 530 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Einstein X-ray Observatory has confirmed the HEAO 1 detection of the NRAO 140 and NRAO 530 quasars, and found that the low-energy X-ray flux of NRAO 140 is consistent with the high-energy results from the earlier satellite. It is also determined that the X-ray emission from NRAO 530 has either decreased by an order of magnitude, from 1978.0 to 1979.7, or the HEAO 1 field contained a second bright source. The two sources have been observed at 2.8 cm, using a four-station intercontinental VLB array, to find whether the X-ray emission is caused by Compton scattering within the radio components. Dissection of the NRAO 140 into its separate components shows radio parameters that imply a 'Compton problem', in that X-ray emission three orders of magnitude greater than that observed is predicted in one of the components if the source is static. Because the effect is independent of distance, relativistic motion with a Lorentz factor greater than about 40 is required to bring the predicted X-ray flux down to the observed value.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 249
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  • 32
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    Observations of SMC X-1 with the monitor proportional counter on the Einstein /HEAO 2/ X-ray Observatory - The pulse period and its history (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The results of the sixth determination of the pulse period of the X-ray source SMC X-1 are presented. The observations were made in April 1979. The pulse period at this epoch was found to be (0.713683 + or - 0.000032) s referred to phase zero of the binary motion. This result together with all available historical data is utilized to quantify the observed trend toward spin-up. It is found that simple secular trends are not applicable. This finding is interpreted as evidence for additional variations in the pulse period. The obtained results are discussed in the context of present theoretical models for period variations in the binary pulsating X-ray sources. The apparent absence of spin-down episodes in the period history of SMC X-1 is also considered.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 33
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    Two-component X-ray emission from RS Canum Venaticorum binaries (1981)
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    Publication Date: 2011-08-18
    Description: A summary is presented of results from the Solid State Spectrometer on the Einstein Observatory for seven RS CVn binaries. The spectra of all require two emission components, evidenced by line emission characteristics of plasma at 4-million to 8-million K and bremsstrahlung characteristic of 20-million to 100-million K. The data are interpreted in terms of magnetic coronal loops similar to those seen on the sun, although with different characteristic parameters. The emission regions could be defined by separate magnetic structures. For pressures less than 10 dynes/sq cm the low temperature plasma would be confined within the stellar radii, while the high temperature plasma would, for the synchronous, close binaries, fill the binary orbits. However, for loop pressures exceeding 100 dynes sq cm, the high temperature components would also be confined to within the stellar radii, in loops covering only small fractions of the stellar surfaces. While the radio properties and the occurrence of X-ray flares suggest the larger emission regions, the observations of time variations leave the ambiguity unresolved.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 34
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    Pulsar gamma-rays - Spectra, luminosities, and efficiencies (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The general characteristics of pulsar gamma-ray spectra are presented for a model in which the gamma rays are produced by curvature radiation from energetic particles above the polar cap and attenuated by pair production. It is found that the shape of the spectrum depends on pulsar period, magnetic field strength, and primary particle energy. Comparing numerically calculated spectra with the observed spectra of the Crab and Vela pulsars, it is determined that primary particles must be accelerated to energies of approximately 3 x 10 to the 7th m c-squared. A general formula is determined for pulsar gamma-ray luminosity; it is found to depend on period and field strength.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 245
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  • 35
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    The Uranus occultation of 10 June 1979. I - The rings (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 86; Apr. 198
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  • 36
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    Infrared observations of AE Aquarii (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Broadband infrared observations of the cataclysmic variable AE Aquarii are reported. The observations were obtained in the J, H, K and L filters with the InSb photometer attached to the 1-m telescope of the European Southern Observatory. The infrared energy distribution observed from 0.35 to 3.5 microns for phase 0.5 suggests a spectral type of K5 V for the secondary and a distance to the system of approximately 70 pc if an absolute magnitude of 7.3 is assumed. Monitoring of the flux at 2.2 microns reveals a variability with an amplitude of approximately 0.3 magnitude over one third of the orbital period, the nature of which is under investigation.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 93
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  • 37
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    Effectiveness of leading-edge vortex flaps on 60 and 75 degree delta wings (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A series of wind tunnel tests were run on 60 and 75 deg sweep delta wings to examine the effectiveness of leading-edge vortex flaps. Tests results showed that leading-edge vortex flaps are effective in giving large increases in lift-to-drag ratio and decreases in drag over a wide range of angle of attack. Tests on inverted flaps on the 60 deg delta wing showed substantial increases in lift and drag and may indicate a possibility of using inverted flaps on delta wings in the landing portion of flight. The 60 deg data were compared with that for a 75 deg sweep delta wing confirming that leading-edge vortex flap effectiveness is stronger as sweep is increased. Pitching moment effects due to vortex flaps use were also examined.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 18; Apr. 198
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  • 38
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    An X-ray survey of nine historical novae (1981)
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    Publication Date: 2011-08-18
    Description: The Einstein Observatory Imaging Proportional Counter has been used to search for X-ray emission from nine nearby historical novae. Six of the novae have been detected with estimated X-ray intensities between 0.1 and 4 keV of 10 to the -13th to 10 to the -11th erg/sq cm-sec, comparable to the intensities of previously detected cataclysmic variables. The X-ray intensity of one of the novae, V603 Aql, varies over times of several hundred seconds. The data suggest a correlation between the decay rate of the historical outburst and the current X-ray luminosity. Alternatively, the X-ray luminosity may be related to the inclination of the binary system.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 244
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  • 39
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    Pulsar and diffuse contributions to observed galactic gamma radiation (1981)
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    Publication Date: 2011-08-18
    Description: The first calculation of a gamma-ray production spectrum from pulsars in the Galaxy, along with a statistical analysis of data on 328 known radio pulsars, are presented. The implications of this point source contribution to the general interpretation of the observed galactic gamma-ray spectrum are indicated. The contributions from diffuse interstellar cosmic-ray induced production mechanisms are then re-examined, concluding that pulsars may be contributing significantly to the galactic gamma-ray emission.
    Keywords: ASTRONOMY
    Type: Nature; 290; Mar. 26
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  • 40
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    Variable X-ray spectra of BL Lacertae objects - HEAO 1 observations of PKS 0548 - 322 and 2A 1219 + 305 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 243
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  • 41
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    Phase-correlated P Cygni profile variations of the C III multiplet in UW Canis Majoris (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The interacting close binary system UW CMa has been observed, in the wavelength range from 1161 to 1188 A, continuously during a complete orbital cycle in 1979 with the Copernicus (OAO-3) U2 spectrometer. The C III multiplet at 1175 A, observed as a P Cygni feature, exhbits a clear dependence on the orbital phase of the binary; the radial velocity variation of this feature lags behind that of the O7 primary component by 0.1 orbital phase, which agrees with the anticipations in an earlier study by the same authors. The radiation-driven matter, flowing out of the binary, originates in the primary component.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 94; 2, Fe; Feb. 198
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  • 42
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    Partially confined multiple jet mixing (1981)
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    Publication Date: 2011-08-18
    Description: Results of hot-wire measurements in an incompressible partially confined jet issuing from an array of rectangular nozzles, equally spaced with their small dimensions aligned are presented. The quantities measured include mean velocity and the Reynolds stress in the two central planes of the jet at stations covering up to 115 widths (small dimension of a nozzle) downstream of the nozzle exit. For downstream distances greater than 60 widths, the flowfield is observed to be nearly homogenous and the turbulence appears to be quite similar to that of a grid generated turbulence.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Mar. 198
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  • 43
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    Unsteady Newton-Busemann flow theory. I - Airfoils (1981)
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    Publication Date: 2011-08-18
    Description: Newtonian flow theory for unsteady flow at very high Mach numbers is completed by the addition of a centrifugal force correction to the impact pressures. The correction term is the unsteady counterpart of Busemann's centrifugal force correction to impact pressures in steady flow. For airfoils of arbitary shape, exact formulas for the unsteady pressure and stiffness and damping-in-pitch derivatives are obtained in closed form, which require only numerical quadratures of terms involving the airfoil shape. They are applicable to airfoils of arbitrary thickness having sharp or blunt leading edges. For wedges and thin airfoils these formulas are greatly simplified, and it is proved that the pitching motions of thin airfoils of convex shape and of wedges of arbitrary thickness are always dynamically stable according to Newton-Busemann theory. Leading-edge bluntness is shown to have a favorable effect on the dynamic stability; on the other hand, airfoils of concave shape tend toward dynamic instability over a range of axis positions if the surface curvature exceeds a certain limit. As a byproduct, it is also shown that a pressure formula recently given by Barron and Mandl for unsteady Newtonian flow over a pitching power-law shaped airfoil is erroneous and that their conclusion regarding the effect of pivot position on the dynamic stability is misleading.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Mar. 198
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  • 44
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    Evidence of imbedded vortices in a three-dimensional shear flow (1981)
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    Publication Date: 2011-08-18
    Description: Vortex phenomena encountered in an investigation of the streamwise development of the three-dimensional wake region behind the tip of a three-dimensional wedge model are reported. Pressure profiles were measured by pitot probes downstream of a tip with a nearly constant surface pressure level and a nearly continuous surface curvature in a blowdown air tunnel operating at Mach 6. Rather than the simple three-dimensional quasi-parallel shear flow expected, the measurements indicated the presence of a flow with large deficits in longitudinal pitot pressure, which are usually associated with the core region of quasi-steady longitudinal vortices. Vapor screen flow visualizations also support the presence of longitudinal vortices located primarily in the tip region and evidently forming in the vicinity of the wake neck. An increase in overall wake thickness by 100% is also observed. The origin of the vortices as quasi-steady Taylor-Gortler vortices generated in the concavely curved shear layer near the wake neck is considered. It is pointed out that the existence of longitudinal vortexes suggests that three-dimensional turbulence modeling may be much more difficult than previously supposed.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Mar. 198
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  • 45
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    VRI photometry of selected SAO stars (1981)
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    Publication Date: 2011-08-18
    Description: Johnson V, R, and I photoelectric photometry has been obtained for 199 SAO stars in support of the Near Infrared Photographic Sky Survey. These data are utilized in the calibration of survey photographs and are presented here to assist other programs reliant upon access to photometry in the photographic infrared.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 92
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  • 46
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    Deformation of a line-element in the phase space at the triangular libration point (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The flow in the projection of the phase space into the configuration space is presented in the neighborhood of a neutrally (or critically) stable equilibrium point in the restricted problem of three bodies. The projection is a line-element every point of which has zero initial velocity. After the elapse of various times the mapping (the rotations and elongations) of the line-element is described showing chaotic behavior.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 23; Feb. 198
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  • 47
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    Stability of outer planetary systems (1981)
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    Publication Date: 2011-08-18
    Description: The conditions for stability in the Liapunov-Hill sense of outer planetary systems are given in terms of radii of planetary orbits. The outer planets of the solar system are found stable and the possible existence of other than the presently known planets between Jupiter and Pluto are indicated. The existence of other planetary systems with arbitrary mass ratios of the primaries is suggested, and the stability conditions for such systems are derived.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 23; Jan. 198
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  • 48
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    In quest of telescopes (1981)
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    Publication Date: 2011-08-18
    Description: This article deals with the author's decision to study star formation and reviews the early days of infrared astronomy at O'Brien Observatory. The infrared equipment used to observe the T Tauri variable class is described.
    Keywords: ASTRONOMY
    Type: Sky and Telescope; 61; Feb. 198
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  • 49
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    Proposed aeroelastic and flutter tests for the National Transonic Facility (1981)
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    Publication Date: 2011-08-18
    Description: Tests that can exploit the capability of the NTF and the transonic cryogenic tunnel, or lead to improvements that could enhance testing in the NTF are discussed. Shock induced oscillation, supersonic single degree control surface flutter, and transonic flutter speed as a function of the Reynolds number are considered. Honeycombs versus screens to smooth the tunnel flow and a rapid tunnel dynamic pressure reducer are recommended to improve tunnel performance.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center High Reynolds Number Res. - 1980; p 153-161
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  • 50
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    Report of the wind tunnel/flight correlation panel (1981)
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    Publication Date: 2011-08-18
    Description: Basic calibration of the tunnel prior to conducting any tests, the areas requiring wind tunnel/flight test correlation for validating the NTF, and recommendations for achieving validation of the NTF are discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center High Reynolds Number Res. - 1980; p 249-262
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  • 51
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    High lift technology (1981)
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    Publication Date: 2011-08-18
    Description: The NASA Langley high lift technology program is reviewed and elements of the program which are considered Reynolds number sensitive are discussed. The Energy Efficient Transport (EET) and Supersonic Cruise Research (SCR) models proposed for high lift studies in the National Transonic Facility (NTF) are described. Recommendations regarding the NTF facility and test techniques are presented.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 197-213
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  • 52
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    Wall interference effects: Status review (1981)
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    Publication Date: 2011-08-18
    Description: The interference technology incorporated into the NTF design (hardware) and the emerging transonic wall interference assessment correction procedures (software) to be employed when the NTF becomes operational was reviewed. It is anticipated that the early experiments will provide data relevant to wall interference effects.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 123-241
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  • 53
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    Configuration aerodynamics (1981)
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    Publication Date: 2011-08-18
    Description: Static aerodynamic research related to aircraft configurations in their cruise or combat modes is discussed. Subsonic transport aircraft, transonic tactical aircraft, and slender wing aircraft are considered. The status and plans of Langley's NTF configuration research program are reviewed. Recommendations for near term configuration research are made.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 217-234
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  • 54
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    Comments on Reynolds number effects and the role of NTF in the development of air vehicles (1981)
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    Publication Date: 2011-08-18
    Description: The National Transonic Facility (NTF) capability to match the full scale Reynolds numbers of all but the largest airplanes is discussed. Conversion factors to enable calculation of Sl-unit equivalents for all U.S. units are listed. Using data from several facilities, analytic methods, and flight test data, a competetive aircraft in the relatively low Reynolds number was developed. The NTF offers the capability to obtain data at full scale Reynolds numbers in the cruise condition for most of the products, and will be much closer than previous tunnels to full scale Reynolds number for the operating envelopes. It is primarily on the operating envelope that Reynolds number effects are most important and least predictable.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center High Reynolds Number Res. - 1980; p 143-148
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  • 55
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    Radio astronomy (1981)
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    Publication Date: 2011-08-18
    Description: The activities of the Deep Space Network in support of Radio Astronomy Operations during April and May 1981 are reported. Work in progres in support of an experiment selected for use of the DSN by the Radio Astronomy Experiment Selection Panel, Twin Quasi-Stellar Object VLBI, is reported.
    Keywords: ASTRONOMY
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 1-9
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  • 56
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    Planetary radar (1981)
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    Publication Date: 2011-08-18
    Description: The radar astronomy activities supported by the Deep Space Network during the first quarter of 1981 are reported. The bodies observed include the asteroids Apollo and Toro, comet Bradfield, and the rings of Saturn.
    Keywords: ASTRONOMY
    Type: The Telecommun. and Data Acquisition Rept.; p 226
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  • 57
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    Radio Astronomy (1981)
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    Publication Date: 2011-08-18
    Description: The activities of the DSN in support of Radio and Radar Astronomy Operations during September through December 1980 are described. Emphasis is on a report of an experiment selected for use of the DSN by the radio Astronomy Experiment Selection Panel: that of VLBI observations of the energetic galactic object SS-433.
    Keywords: ASTRONOMY
    Type: Telecommun. and Data Acquisition; p 1-2
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  • 58
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    Photovoltaics (1981)
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    Publication Date: 2011-08-18
    Description: The federal government has sponsored a program of research and development on terrestrial photovoltaic systems that is designed to reduce the costs of such systems through technological advances. There are many potential paths to lower system costs, and successful developments have led to increased private investment in photovoltaics. The prices for photovoltaic collectors and systems that appear to be achievable within this decade offer hope that the systems will soon be attractive in utility applications within the United States. Most of the advances achieved will also be directly applicable to the remote markets in which photovoltaic systems are now commercially successful
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Science; 212; June 26
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  • 59
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    Spectroscopy of the B-gamma line in the Galactic center (1981)
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    Publication Date: 2011-08-18
    Description: Spectra of the B-gamma recombination line of hydrogen in the Galactic center show that the line has central velocities and shapes similar to those reported previously for the Ne II line. Observations are made at 10 positions within the infrared cluster of the Galactic center with a circular diaphragm of diameter 5 arcsec and with a spectral resolution of approximately 85 km/sec. The spectra confirm that the ionized gas in the Galactic center is distributed in discrete clouds.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 86; Apr. 198
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  • 60
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    The 1980 June X-ray high state of Cygnus X-1 - Optical changes (1981)
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    Publication Date: 2011-08-18
    Description: UBV photometry of Cygnus X-1 is reported from before, during, and after the 1980 June X-ray high state discovered by the Hakucho satellite. A darkening was recorded around orbital phase 0.25, also near phase 0.0, which persisted for over a month after the X-ray episode. The brightness around phase 0.75 remained normal. Light curves from preceding years are compared. Preliminary mention is also made of polarization changes during the high state.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 244
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  • 61
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    The NASA/Marshall Space Flight Center program in gamma-ray burst astronomy (1981)
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    Publication Date: 2011-08-18
    Description: The research program in gamma-ray burst astronomy at the NASA/Marshall Space Flight Center is described. Large-area scintillation detector arrays have been flown on high-altitude balloons, and an array is being developed for the Gamma-Ray Observatory. The design of these detectors is described along with results obtained from previous balloon flights.
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  • 62
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    The Goddard program of gamma-ray transient astronomy (1981)
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    Publication Date: 2011-08-18
    Description: The Goddard program of gamma-ray burst studies is briefly reviewed. The past results, present status and future expectations are outlined regarding our endeavors using experiments on balloons. IMP-6 and IMP-7, OGO-3, ISEE-1 and ISEE-3, Helios-2, Solar Maximum Mission, the Einstein Observatory, Solar Polar and the Gamma Ray Observatory, and with the interplanetary gamma-ray burst networks, to which some of these spacecraft sensors contribute. Additional emphasis is given to the recent discovery of a new type of gamma-ray transient, detected on 5 March, 1979.
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  • 63
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    Solution of the transonic full potential equation in conservative form using an implicit algorithm (1981)
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    Publication Date: 2011-08-18
    Description: The paper presents numerical solutions of the full potential equation in conservative form. The iteration scheme used is a fully implicit approximate factorization technique and provides a significant improvement in convergence speed relative to standard successive line overrelaxation algorithms. The spatial differencing algorithm is centrally differenced in both subsonic and supersonic regions to maintain stability. This effectively approximates rotated differencing, thereby greatly improving the reliability of the algorithm.
    Keywords: AERODYNAMICS
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  • 64
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    Production of hydrogen by electron transfer catalysis using conventional and photochemical means (1981)
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    Publication Date: 2011-08-18
    Description: Alternate methods of generating hydrogen from the sulfuric acid thermal or electrochemical cycles are presented. A number of processes requiring chemical, electrochemical or photochemical methods are also presented. These include the design of potential photoelectrodes and photocatalytic membranes using Ru impregnated nafion tubing, and the design of experiments to study the catalyzed electrolytic formation of hydrogen and sulfuric acid from sulfur dioxide and water using quinones as catalysts. Experiments are carried out to determine the value of these approaches to energy conversion.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Courtesy Associates, Inc. Proc. of the DOE Thermal and Chem. Storage Ann. Contractor's Rev. Meeting; p 233-236
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  • 65
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    Overview of the Chemical/Hydrogen Energy Systems (C/HES) program (1981)
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    Publication Date: 2011-08-18
    Description: The production, storage and transmission, and utilization of hydrogen are included. Management structure and the programmatic emphasis are summarized.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Courtesy Associates, Inc. Proc. of the DOE Thermal and Chem. Storage Ann. Contractor's Rev. Meeting; p 141-144
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    Chemical/Hydrogen Energy Storage Systems (1981)
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    Publication Date: 2011-08-18
    Description: Electrochemical and thermochemical systems are reviewed. Chemical heat pumps, end-use applications and systems studies, and storage systems and materials are also discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Courtesy Associates, Inc. Proc. of the DOE Thermal and Chem. Storage Ann. Contractor's Rev. Meeting; p 145-149
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  • 67
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    An experimental study of SO3 dissociation as a mechanism for converting and transporting solar energy (1981)
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    Publication Date: 2011-08-18
    Description: The high temperature catalytic dissocation of SO3 is an important chemical process being considered in the development and application of solar-thermal energy conversion, transport, and storage systems. A facility for evaluating chemical converter-heat exchangers at temperatures to 1000 C with high flow rates of gaseous SO3 feedstock has been assembled and operated on the NMSU campus. Several quartz and metal reactors containing different catalyst configurations have been tested. Descriptions of the test facility and of the reactors are given along with a presentation and discussion of experimental results.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Energy; 27; 5, 19; 1981
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  • 68
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    Computation of airfoil buffet boundaries (1981)
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    Publication Date: 2011-08-18
    Description: The ILLIAC IV computer has been programmed with an implicit, finite-difference code for solving the thin layer compressible Navier-Stokes equation. Results presented for the case of the buffet boundaries of a conventional and a supercritical airfoil section at high Reynolds numbers are found to be in agreement with experimentally determined buffet boundaries, especially at the higher freestream Mach numbers and lower lift coefficients where the onset of unsteady flows is associated with shock wave-induced boundary layer separation.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Nov. 198
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  • 69
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    An investigation of the neutral and ionized gas in M16 (1981)
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    Publication Date: 2011-08-18
    Description: An attempt is made to understand the physical and kinematic conditions in the M16 active star formation site, by means of mapping observations of neutral and ionized hydrogen and observations of (C-12)O from selected positions within the H II regions. The 21-cm maps suggest that at least two neutral clouds are present in the M16 complex, one of which is likely to be the remains of the cloud in which star formation initially occurred, and the other is probably the cold gas remaining from a disrupted cloud edge where the ionization front has crossed the cloud-intercloud boundary. Multislit echelle spectra of the H-alpha line are obtained to determine the physical conditions within the ionized gas, and H-alpha maps show that the ionized gas is systematically blueshifted in the east and splits into two streams in the southwest.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 248
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  • 70
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    Production cost comparisons of hydrogen from fossil and nuclear fuel and water decomposition (1981)
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    Publication Date: 2011-08-18
    Description: The comparative costs entailed in producing hydrogen by major technologies that rely on petroleum, natural gas, coal, thermochemical cycles, and electrolysis are examined. Techniques were developed for comparing these processes by formulating the process data and economic assessments on a uniform and consistent basis. These data were normalized to permit a meaningful comparative analysis of product costs of these processes.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Courtesy Associates, Inc. Proc. of the DOE Thermal and Chem. Storage Ann. Contractor's Rev. Meeting; p 227-231
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  • 71
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    Orbiter fuel cell improvement assessment (1981)
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    Publication Date: 2011-08-18
    Description: The history of fuel cells and the theory of fuel cells is given. Expressions for thermodynamic and electrical efficiencies are developed. The voltage losses due to electrode activation, ohmic resistance and ionic diffusion are discussed. Present limitations of the Orbiter Fuel Cell, as well as proposed enhancements, are given. These enhancements are then evaluated and recommendations are given for fuel cell enhancement both for short-range as well as long-range performance improvement. Estimates of reliability and cost savings are given for enhancements where possible.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. fellowship Program, Vol. 1; 27 p
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  • 72
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    Contact resistivities of sputtered TiN and Ti-TiN metallizations on solar-cell-type-silicon (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The resistivities of TiN and Ti-TiN contacts on a shallow junction solar-cell-type silicon substrate have been determined by the method of the transmission line model. The contacts investigated are shown to be suitable for standard solar cells from an electrical point of view. Contact resistivity values of the order of 0.0001 ohm/sq cm as obtained for the n(+)Si-TiSi2-TiN contact system may be acceptable for concentrations up to 100 times, but lower values are necessary beyond this point.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Energy; 27; 4, 19; 1981
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  • 73
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    The Sixth Catalogue of galactic Wolf-Rayet stars, their past and present (1981)
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    Publication Date: 2011-08-18
    Description: This paper presents the Sixth Catalogue of galactic Wolf-Rayet stars (Pop. I), a short history on the five earlier WR catalogues, improved spectral classification, finding charts, a discussion on related objects, and a review of the current status of Wolf-Rayet star research. The appendix presents a bibliography on most of the Wolf-Rayet literature published since 1867.
    Keywords: ASTRONOMY
    Type: Space Science Reviews; 28; 3, 19; 1981
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  • 74
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    Observations of faint Haro galaxies (1981)
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    Publication Date: 2011-08-18
    Description: Spectroscopic and photometric data for 23 faint-compact UV-excess galaxy candidates, found by Haro's three-color technique (1956), are presented. Eighteen were found to be emission-line galaxies (magnitudes between 14.4 and 17.9) with redshifts in the range of 1670 to 39,450 km/s; the remaining five appear to be stars. The apparent compactness of the galaxy images is a result of the finite resolution of the Survey plates. Faint Haro galaxies are not distinguishable from the original Haro galaxies in surface brightness or in their range of color and absolute magnitude. The Haro galaxies correspond to roughly two-thirds of Huchra's non-Seyfert Markarian galaxies (1977 a) which have the most negative (U-B) index; the new Haro galaxies have the same V magnitude growth with aperture, the same (B-V) aperture relation, and the same mean surface brightness as the Markarian galaxies.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 93
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  • 75
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    A solar extreme ultraviolet telescope and spectrograph for Shuttle/Spacelab (1981)
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    Publication Date: 2011-08-18
    Description: An instrument for advanced studies of the solar corona is described. Its optical system provides nearly stigmatic imaging of selected portions of the sun over the spectral range from 22.5 to 44.0 nm. Both spectroheliograms and emission line profiles of coronal features will be obtained over a wide range of coronal temperatures.
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  • 76
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    The Solar Optical Telescope /SOT/ (1981)
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    Publication Date: 2011-08-18
    Description: The Solar Optical Telescope (SOT) is a 1-m class, high resolution solar telescope which NASA plans to operate on the Shuttle Spacelab during the mid and late 1980's. SOT will provide resolution down to 0.1 arcsec, and can therefore be used to solve many problems of solar atmosphere structure and dynamics. In particular, SOT should provide definite data on (1) the source of the sun's magnetic field, (2) the amount of power in waves generated in the photosphere, (3) the heating of the chromosphere, and (4) the local and global mass and energy balance in the solar transition region. The SOT Scientific Working Group will help plan, develop, and update the overall scientific plan for the SOT, as well as make recommendations with regard to the SOT project, instrumentation optimization, and scientific data management.
    Keywords: ASTRONOMY
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  • 77
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    Status of the microwave power transmission components for the solar power satellite (1981)
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    Publication Date: 2011-08-18
    Description: During the 1970-1980 time period a substantial advance has been made in developing all portions of a microwave power transmission system for the solar power satellite (SPS). The most recent advances pertain to the transmitting portion of the system in the satellite and are based upon experimental observations of the use of the magnetron combined with a passive directional device to convert it into a highly efficient directional amplifier with excellent low-noise properties and potentially very long life. The ability of its microwave output to track a phase reference makes it possible to combine it with many other radiating units to provide a highly coherent microwave beam. The ability of its output to track an amplitude reference while operating from a dc power source with varying voltage makes it possible to eliminate most of the power conditioning equipment that would otherwise be necessary.
    Keywords: ENERGY PRODUCTION AND CONVERSION
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  • 78
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    The planetary nebula NGC 6826 (1981)
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    Publication Date: 2011-08-18
    Description: Monochromatic photographs have established the NGC 6826 nebula as the third member of a group of very rare triple-shell planetaries (Feibelman, 1971, 1974). Kaler (1974) also characterized NGC 6826 as a giant halo planetary. Numerous errors and confusing statements regarding its size, structure and stratification are discussed, and the correct dimensions of the nebula are reported: the inner ring is 12.7 arcsec x 8.7 arcsec (Feibelman, 1971); the outer ring is 27 arcsec x 24 arcsec according to Curtis (1918), 25.7 arcsec x 24.4 arcsec according to Feibelman (1971), and 36 arcsec x 36 arcsec according to Coleman et al. (1975). The halo measurements range in diameter from 110 arcsec (Duncan, 1937) to 130 arcsec (Kaler, 1974) to 142 arcsec (Millikan, 1974). Values for the distance of NGC 6826 range from 0.75-1.16 kpc (Cahn and Kaler, 1971) to 2.265 kpc (Cudworth, 1974).
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 93
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  • 79
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    On the definition of albedo and application to irregular particles (1981)
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    Publication Date: 2011-08-18
    Description: The various definitions of albedo used in planetary astronomy are reviewed. In particular, the Bond albedo, which refers only to the reflected and refracted components, is not applicable to small particles or highly irregular particles, where diffraction is not restricted to a well-defined lobe at small scattering angles. Measured scattering functions for irregular particles are presented in a normalized form and are applied to the case of zodiacal light.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 104; 1, De; Dec. 198
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  • 80
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    Rapid X-ray variability in the Seyfert galaxy NGC 6814 (1981)
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    Publication Date: 2011-08-18
    Description: In contrast with the Tennant et al (1981) sample of over 30 active galactic nuclei, HEAO 1 A-2 high time resolution X-ray observations of the X-ray emitting Seyfert 1 galaxy NGC 6814 show strong X-ray variability on time scales of less than 3 hr. On a time scale of 90 min, the mean flux varied by a factor of about 2.5, and a characteristic time for variability of 100 + 60 or - 25 sec is obtained by autocorrelation analysis. There is no indication of spectral variability with an upper limit on a change in the power law spectral index of less than about 0.37, for a factor 2 change in intensity. The constraints of such rapid variability on a range of X-ray source mechanisms is discussed.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 251
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  • 81
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    The X-ray structure of Centaurus A (1981)
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    Publication Date: 2011-08-18
    Description: The Einstein X-ray observatory imaging detectors have found X-ray emission associated with several components of the nearby radio galaxy Cen A = NGC 5128: (1) the compact nucleus; (2) an X-ray jet pointed toward the NE radio lobes; (3) the middle NE radio lobe; (4) the disk or dust lane; and (5) diffuse emission extending several arcmin around the nucleus. The intensity of the nucleus changed by a factor of seven over six months. The X-ray jet is considered in terms of thermal, inverse Compton, and synchrotron models. The emission of the NE radio lobe is greater than that expected from inverse Compton or synchrotron processes. Two ridges of emission are found along each edge of the dust lane, within several arcmin of the nucleus. The diffuse X-ray component has a luminosity which is too high to be due to bulge population X-ray sources, but which may be produced by main sequence stars under appropriate circumstances.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 251
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  • 82
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    Spatial observations of the Orion Nebula in the unidentified 3.28 micron feature (1981)
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    Publication Date: 2011-08-18
    Description: The unidentified infrared emission at a wavelength of 3.28 microns has been mapped in a 5 x 5 arcmin region of the Orion Nebula at a resolution of 30 arcsec along with continuum thermal emission at 3.5 microns in order to gain information on the probable source of the unidentified feature. The 3.28-micron emission is found to be extended over much of the nebula with a distribution very different from that of the 3.5-micron continuum. The ratio of 3.28-micron to 3.5-micron flux density is observed to range from a value of 7 in the Orion ionization ridge to less than 0.15 towards the Becklin-Neugebauer object, and to generally be larger toward the edges of the emitting region than toward the Trapezium. From the observations, it is concluded that the 3.28-micron emission originates in the ionization front between the foreground ionized gas and background molecular cloud, and may be due to thermal emission from complex, less volatile organic substances in grain mantles.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 245
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  • 83
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    Future prospects for gamma-ray astronomy (1981)
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    Publication Date: 2011-08-18
    Description: As gamma-ray astronomy moves from the discovery to the exploratory phase, the promise of gamma-ray astrophysics noted by theorists in the late 1940s and 1950s is beginning to be realized. In the future, satellites should carry instruments that will have over an order of magnitude greater sensitivity than those flown thus far, and, for at least some portions of the gamma-ray energy range, these detectors will also have substantially improved energy and angular resolution. The information to be obtained from these experiments should greatly enhance our knowledge of several astrophysical phenomena including the very energetic and nuclear processes associated with compact objects, astrophysical nucleosynthesis, solar particle acceleration, the chemical composition of the planets and other bodies of the solar system, the structure of our galaxy, the origin and dynamic pressure effects of the cosmic rays, high energy particles and energetic processes in other galaxies especially active ones, and the degree of matter-antimatter symmetry of the universe. The gamma-ray results of the forthcoming programs such as Gamma-I, the Gamma Ray Observatory, the gamma-ray burst network, Solar Polar, and very high energy gamma-ray telescopes on the ground will almost certainly provide justification for more sophisticated telescopes. These advanced instruments might be placed on the Space Platform currently under study by N.A.S.A.
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  • 84
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    The properties of close multiple stars (1981)
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    Publication Date: 2011-08-18
    Description: A reexamination of the properties of close multiple systems is conducted, taking into account recent numerical, analytical, and observational results. The orbital elements of 43 spectroscopic multiple systems are presented in a table. Tables with photometry data of the systems and data describing their properties are also provided. Attention is given to period ratios, mass ratios, orbital coplanarity, stability, lithium abundances and age estimates, and prospects of future observations. Numerical studies indicate that fragmentation produces binary components with mass ratios usually close to 1.0, while fission usually produces mass ratios in the range 0.1-0.5. Using analytical stability criteria, all 27 close multiple systems considered are stable if they are corotating. If they are counter-rotating, four systems are possibly unstable. However, other factors suggest that even these four are probably stable. The solar-type close multiple systems ranged in age from 100 million years to 2,000 million years.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 85
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    Dispersed solar thermal generation employing parabolic dish-electric transport with field modulated generator systems (1981)
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    Publication Date: 2011-08-18
    Description: This paper discusses the application of field modulated generator systems (FMGS) to dispersed solar-thermal-electric generation from a parabolic dish field with electric transport. Each solar generation unit is rated at 15 kWe and the power generated by an array of such units is electrically collected for insertion into an existing utility grid. Such an approach appears to be most suitable when the heat engine rotational speeds are high (greater than 6000 r/min) and, in particular, if they are operated in the variable speed mode and if utility-grade a.c. is required for direct insertion into the grid without an intermediate electric energy storage and reconversion system. Predictions of overall efficiencies based on conservative efficiency figures for the FMGS are in the range of 25 per cent and should be encouraging to those involved in the development of cost-effective dispersed solar thermal power systems.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Energy; 27; 1, 19; 1981
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  • 86
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    HD 202908 - A young, solar-type triple system (1981)
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    Publication Date: 2011-08-18
    Description: HD 202908 is a solar-type, spectroscopic-visual triple system. High-dispersion spectroscopic observations show that the primary visual component is a double-lined spectroscopic binary with a period of 3.966 days and a mass ratio of 1.0. Velocity changes due to motion in the long-period, 76-year orbit are now perceptible. Over the next 5 years, these changes may amount to 30 km/s for the single star. Continued spectroscopic and visual observations through nodal and periastron passage of the highly eccentric visual orbit, which will occur nearly simultaneously about 1985.5, will permit the accurate determination of the masses and luminosities of the three components. Contrary to expectation, the short-period and long-period orbits are not coplanar. The large lithium abundances, strength of the Ca II emission lines, and rotational velocities all suggest that this multiple system has an age similar to that of the Hyades cluster.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 248
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  • 87
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    Infrared charge-injection-device array performance at low background (1981)
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    Publication Date: 2011-08-18
    Description: Low-background tests of a 1 x 32 Si:Bi charge-injection-device (CID) IR detector are carried out to evaluate its feasibility for space-based astronomical observations. Optimum performance is obtained at a temperature of 11 K. The sensitivity is found to compare well with that of discrete extrinsic silicon photoconductors. The measured sensitivity and the apparent absence of anomalous effects make extrinsic silicon CID arrays very promising for astronomical applications.
    Keywords: ASTRONOMY
    Type: Applied Optics; 20; Sept. 15
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  • 88
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    Application of unsteady airfoil theory to rotary wings (1981)
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    Publication Date: 2011-08-18
    Description: A clarification is presented on recent work concerning the application of unsteady airfoil theory to rotary wings. The application of this theory may be seen as consisting of four steps: (1) the selection of an appropriate unsteady airfoil theory; (2) the resolution of that velocity which is the resultant of aerodynamic and dynamic velocities at a point on the elastic axis into radial, tangential and perpendicular components, and the angular velocity of a blade section about the deformed axis; (3) the expression of lift and pitching moments in terms of the three components; and (4) the derivation of explicit expressions for the components in terms of flight velocity, induced flow, rotor rotational speed, blade motion variables, etc.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 18; July 198
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  • 89
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    Optical monitoring of 15 quasars (1981)
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    Publication Date: 2011-08-18
    Description: The data of fifteen quasars are analyzed to determine how well a short-term program of observation can characterize the general optical behavior as compared to a long-term program. Three major research objectives were pursued, namely, to measure archival brightness of the quasars, to compare the brightness observed (mid-1970) to that of the Harvard historical plate collection 1900-1950, and to compare the general behavior during a short-time (two years) to that found over 50 years. Results show that in eight of the 15 quasars the mean magnitude derived from the present short-epoch program differed by 0.11 mag or less from the mean determined in the long-epoch program. The mean difference for all 15 quasars was 0.20 mag. However, in two cases, the short program failed by 0.83 and 0.66 mag, respectively, in predicting the mean brightness. The largest rate of increase in brightness observed was 0.9 mag/day (3C263) and of decrease was 0.44 (3C345), and it is concluded that the rates of decrease and increase in brightness are essentially the same.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 86; May 1981
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  • 90
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    Determination of the potential in a synodic system (1981)
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    Publication Date: 2011-08-18
    Description: Determination of the potential field in a fixed (inertial) system may be accomplished by the solution of a homogeneous linear partial differential equation when a family of orbits of a body moving in the field is given. This partial differential equation was presented and thoroughly analyzed earlier. The present paper discusses the same problem in a rotating system where the centrifugal and Coriolis effects render the pertinent partial differential equation in general non-homogeneous and non-linear. A linear, though non-homogeneous, partial differential equation for the determination of the synodic potential is obtained only in the special case of iso-energetic families of orbits.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 24; May 1981
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  • 91
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    Measurements of forbidden line radiation of Ar II /6.99 microns/ in W3 IRS 1 (1981)
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    Publication Date: 2011-08-18
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 244
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  • 92
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    Morphological study of the time histories of gamma-ray bursts (1981)
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    Publication Date: 2011-08-18
    Description: Time histories of gamma-ray bursts have revealed a great diversity, both in total duration and in the details of fine time structure. Results of the gamma-ray experiment on the Helios-2 spacecraft have suggested some similarities in time profiles of events. The possibility of some characteristic 'separation times' in events may also be indicated.
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  • 93
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    The coupling between flow instabilities and incident disturbances at a leading edge (1981)
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    Publication Date: 2011-08-18
    Description: It is now generally agreed that an external disturbance field, such as an incident acoustic wave, can effectively couple to instabilities of a flow past a trailing edge. One purpose of the present paper is to show that there are situations where a similar coupling can occur at a leading edge. The process is analyzed and the effects of experimentally controllable parameters are assessed. It is important to account for such phenomena when evaluating the effect of external disturbances on transition.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 104; Mar. 198
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  • 94
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    A discrete vortex method for the non-steady separated flow over an airfoil (1981)
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    Publication Date: 2011-08-18
    Description: A discrete vortex method was used to analyze the separated non-steady flow about a cambered airfoil. The foil flow modelling is based on the thin lifting-surface approach, where the chordwise location of the separation point is assumed to be known from experiments or flow-visualization data. Calculated results provided good agreement when compared with the post-stall aerodynamic data of two airfoils. Those airfoil sections differed in the extent of travel of the separation point with increasing angle of attack. Furthermore, the periodic wake shedding was analyzed and its time-dependent influence on the airfoil was investigated.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 102; Jan. 198
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  • 95
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    High-speed photometry of the 11 December 1979 Juno occultation (1981)
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    Publication Date: 2011-08-18
    Description: The occultation of SAO 115946 by Juno on 11 December 1979 was observed from two sites in southern California with portable two-color, high-speed photometers. A composite light curve was constructed from the data by suitable scaling of individual observations, using an astrometric solution for the location of the contact points on Juno's limb. The preliminary astrometric solution used here has a semiminor axis of 118 km and a semimajor axis of 145 km at position angle 75.5 deg. The composite light curve is compatible with a stellar radius of (1.6 + or - 0.8) x 10 to the -4th arcsec, consistent with the radius estimated from the color and visual magnitude. There is no evidence for any companions to SAO 115946 or Juno. The prospects for use of asteroid occultations to determine stellar radii and asteroid surface slopes are discussed as compared with the lunar occultation technique.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 86; Jan. 198
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  • 96
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    The properties of polycrystalline silicon solar cells with controlled titanium additions (1981)
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    Publication Date: 2011-08-18
    Description: By coupling the results of electrical measurements, such as spectral response, lighted and dark I-V determinations, and deep-level-transient spectroscopy with optical and laser scan photomicroscopy, the effects of grain boundaries and impurities on silicon solar cells were evaluated. Titanium, which produces two deep levels in silicon, degrades cell performance by reducing bulk lifetime and thus cell short-circuit current. Electrically active grain boundaries induce carrier recombination in the bulk and depletion regions of the solar cell. Experimental data imply a small but measurable segregation of titanium into some grain boundaries of the polycrystalline silicon containing high Ti concentration. However, for the titanium-contaminated polycrystalline material used in this study, solar cell performance is dominated by the electrically active titanium concentration in the grains. Microstructural impacts on the devices are of secondary importance
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Transactions on Electron Devices; ED-28; Jan. 198
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  • 97
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    Pathfinder model program for the National Transonic Facility (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An overview of the Pathfinder Models Program is presented. The Pathfinder program is a major research and development activity in support of the National Transonic Facility Activation Plan. The program scope, models design approach, and Pathfinder model configurations are presented along with a discussion of major supportive program activities. The anticipated design criteria for NTF models are presented.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 37-52
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  • 98
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    Assessment of solar-assisted gas-fired heat pump systems (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: As a possible application for the Goldstone Energy Project, the performance of a 10 ton heat pump unit using a hybrid solar gas energy source was evaluated in an effort to optimize the solar collector size. The heat pump system is designed to provide all the cooling and/or heating requirements of a selected office building. The system performance is to be augmented in the heating mode by utilizing the waste heat from the power cycle. A simplified system analysis is described to assess and compute interrrelationships of the engine, heat pump, and solar and building performance parameters, and to optimize the solar concentrator/building area ratio for a minimum total system cost. In addition, four alternative heating cooling systems, commonly used for building comfort, are described; their costs are compared, and are found to be less competitive with the gas solar heat pump system at the projected solar equipment costs.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: The Telecommun. and Data Acquisition Rept.; p 154-190
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  • 99
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    Computer simulated building energy consumption for verification of energy conservation measures in network facilities (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A computer program called ECPVER (Energy Consumption Program - Verification) was developed to simulate all energy loads for any number of buildings. The program computes simulated daily, monthly, and yearly energy consumption which can be compared with actual meter readings for the same time period. Such comparison can lead to validation of the model under a variety of conditions, which allows it to be used to predict future energy saving due to energy conservation measures. Predicted energy saving can then be compared with actual saving to verify the effectiveness of those energy conservation changes. This verification procedure is planned to be an important advancement in the Deep Space Network Energy Project, which seeks to reduce energy cost and consumption at all DSN Deep Space Stations.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Telecommun. and Data Acquisition; p 142-146
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  • 100
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    Fuel cells feasibility (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The technical and economic status of fuel cells is assessed with emphasis on their potential benefits to the Deep Space Network. The fuel cell, what it is, how it operates, and what its outputs are, is reviewed. Major technical problems of the fuel cell and its components are highlighted. Due to these problems and economic considerations it is concluded that fuel cells will not become commercially viable until the early 1990s.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: The Telecommun. and Data Acquisition; p 154-168
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