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  • ASTROPHYSICS  (30)
  • CYBERNETICS  (5)
  • FLUID MECHANICS AND HEAT TRANSFER  (5)
  • 1990-1994  (40)
  • 1
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    Selection effects and binary galaxy velocity differences (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Measurements of the velocity differences (delta v's) in pairs of galaxies from large statistical samples have often been used to estimate the average masses of binary galaxies. A basic prediction of these models is that the delta v distribution ought to decline monotonically. However, some peculiar aspects of the kinematics have been uncovered, with an anomalous preference for delta v approx. equal to 72 km s(sup-1) appearing to be present in the data. The authors examine a large sample of binary galaxies with accurate redshift measurements and confirm that the distribution of delta v's appears to be non-monotonic with peaks at 0 and approx. 72 km s (exp -1). The authors suggest that the non-zero peak results from the isolation criteria employed in defining samples of binaries and that it indicates there are two populations of binary orbits contributing to the observed delta v distribution.
    Keywords: ASTROPHYSICS
    Type: NASA, Marshall Space Flight Center, Paired and Interacting Galaxies: International Astronomical Union Colloquium No. 124; p 485-490
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  • 2
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    Massive low surface brightness galaxies (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A multi-wavelength study of an extreme type of galaxy which will assist us in our attempts to understand the formation and evolution of galaxies was completed. In particular, a subset of low surface brightness (bar-mu(sub B) is approximately greater than 25 mag arcsec(sup -2)), giant galaxies (LSBG's) which contain large amounts of atomic gas (M(HI) is approximately greater than 10(exp 10) solar mass), have blue optical diameters similar to those of giant spiral galaxies, but which do not seem to have prodigious amounts of ongoing star formation were observed. Our sample was drawn from the first and second Palomar Sky Surveys. This population of galaxies has been largely ignored because of selection effects which make it difficult to detect optically. The question of how these massive systems differ from the higher surface brightness 'normal' spiral galaxies is addressed. Using B and R surface photometry, in conjunction with H-alpha, HI, CO-12, and far-infrared data, an attempt is made to determine if these galaxies had an early epoch of star formation that has since faded, have ongoing star formation with an unusual interplanetary magnetic field (IMF), or are perhaps galaxies which have never efficiently formed stars due to a lack of molecular clouds.
    Keywords: ASTROPHYSICS
    Type: NASA. Ames Research Center, The Evolution of Galaxies and Their Environment; p 84-85
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  • 3
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    Computation of solid/liquid phase change including free convection - Comparison with data (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A computational model is presented for solid/liquid phase-change energy transport including free convection fluid flow in the liquid phase. The computational model considers the velocity components of all nonliquid control volumes to be zero but fully solves the coupled mass-momentum problem within the liquid. The thermal energy model includes the entire domain and employs an enthalpy-like model and a recently developed method for handling the phase-change interface nonlinearity. Convergence studies are performed and comparisons made with experimental data for two different problems. Grid independence is achieved, and the comparison with experimental data indicates excellent quantitative prediction of the melt fraction evolution. Qualitative data are also provided as velocity vector and isotherm plots. The computational costs incurred are quite low by comparison with other models.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Thermophysics and Heat Transfer (ISSN 0887-8722); 4; 366-374
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  • 4
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    Holt film wall shear instrumentation for boundary layer transition research (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Measurements of the performance of hot-film wall-shear sensors were performed to aid development of improved sensors. The effect of film size and substrate properties on the sensor performance was quantified through parametric studies carried out both electronically and in a shock tube. The results show that sensor frequency response increases with decreasing sensor size, while at the same time sensitivity decreases. Substrate effects were also studied, through parametric variation of thermal conductivity and heat capacity. Early studies used complex dual-layer substrates, while later studies were designed for both single-layer and dual-layer substrates. Sensor failures and funding limitations have precluded completion of the substrate thermal-property tests.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-196040 , NAS 1.26:196040
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  • 5
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    An intelligent position-specific training system for mission operations (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Marshall Space Flight Center's (MSFC's) payload ground controller training program provides very good generic training; however, ground controller position-specific training can be improved by including position-specific training systems in the training program. This report explains why MSFC needs to improve payload ground controller position-specific training. The report describes a generic syllabus for position-specific training systems, a range of system designs for position-specific training systems, and a generic development process for developing position-specific training systems. The report also describes a position-specific training system prototype that was developed for the crew interface coordinator payload operations control center ground controller position. The report concludes that MSFC can improve the payload ground controller training program by incorporating position-specific training systems for each ground controller position; however, MSFC should not develop position-specific training systems unless payload ground controller position experts will be available to participate in the development process.
    Keywords: CYBERNETICS
    Type: NASA-TM-108381 , NAS 1.15:108381
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  • 6
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    Design of a cavity heat pipe receiver experiment (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A cavity heat pipe experiment has been designed to test the critical issues involved with incorporating thermal energy storage canisters into a heat pipe. The experiment is a replication of the operation of a heat receiver for a Brayton solar dynamic power cycle. The heat receiver is composed of a cylindrical receptor surface and an annular heat pipe with thermal energy storage canisters and gaseous working fluid heat exchanger tubes surrounding it. Hardware for the cavity heat pipe experiment will consist of a sector of the heat pipe, complete with gas tube and thermal energy storage canisters. Thermal cycling tests will be performed on the heat pipe sector to simulate the normal energy charge/discharge cycle of the receiver in a spacecraft application.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: In: IECEC '92; Proceedings of the 27th Intersociety Energy Conversion Engineering Conference, San Diego, CA, Aug. 3-7, 1992. Vol. 2 (A93-25851 09-44); p. 2.369-2.375.
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  • 7
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    Luminosity function of quasars at large redshifts from grism surveys (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: We have carried out a systematic search for emission-line objects through photometrically calibrated CCD grism surveys with the Palomar 200-inch telescope in transit mode, covering 62 square degrees. These surveys have yielded 141 quasars detected by their C IV or Ly-alpha emission in the redshift range 2.0 - 4.7. We use this sample and the known flux limits to derive the slope of the luminosity function and the space density above a given line luminosity, as a function of redshift. While space densities are approximately constant at redshifts 2.0 - 3.0, they are declining steeply for redshifts larger than 3.
    Keywords: ASTROPHYSICS
    Type: In: The space distribution of quasars; Proceedings of the Workshop, Victoria, Canada, June 3-5, 1991 (A93-28776 10-90); p. 109-114; Discussi
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  • 8
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    ControlShell: A real-time software framework (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The ControlShell system is a programming environment that enables the development and implementation of complex real-time software. It includes many building tools for complex systems, such as a graphical finite state machine (FSM) tool to provide strategic control. ControlShell has a component-based design, providing interface definitions and mechanisms for building real-time code modules along with providing basic data management. Some of the system-building tools incorporated in ControlShell are a graphical data flow editor, a component data requirement editor, and a state-machine editor. It also includes a distributed data flow package, an execution configuration manager, a matrix package, and an object database and dynamic binding facility. This paper presents an overview of ControlShell's architecture and examines the functions of several of its tools.
    Keywords: CYBERNETICS
    Type: AIAA PAPER 94-0890-CP , NASA. Johnson Space Center, Conference on Intelligent Robotics in Field, Factory, Service and Space (CIRFFSS 1994), Volume 2; p 870-877
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  • 9
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    The network data delivery service: A real-time data connectivity system (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A network data-sharing system, the Network Data Delivery Service (NDDS), is discussed. The NDDS system relies on a bipartite model consisting of the following: information producers (sources) and information consumers (sinks). The example provided by a dual-arm robotic system is examined.
    Keywords: CYBERNETICS
    Type: AIAA PAPER 94-0889-CP , NASA. Johnson Space Center, Conference on Intelligent Robotics in Field, Factory, Service and Space (CIRFFSS 1994), Volume 2; p 591-598
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  • 10
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    The HST Quasar Absorption-Line Key Project. 8: CCD imaging of Hubble Space Telescope quasar fields (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We present an analysis of CCD images of more than 100 quasars; many of the objects have been or will be observed in the Hubble Space Telescope (HST) Key Project Quasar Absorption-Line Survey. The data set consists of B, g, and i photometry of 117 quasars and deeper g (limiting magnitude of approximately equal 22) images of 101 quasar fields. Positions accurate to approximately equal 1 sec, measured with the Space Telescope Science Institute's Astrometric Support Program, are listed for all of the quasars in this study. Positions, magnitudes, and classifications of stars and galaxies located within approximately equal 100 sec of the quasars are given for all of the deep g data. The positions of the stars and galaxies relative to the quasar are accurate to approximately equal 0.5 sec. The results presented here can be used to prepare spectroscopic programs designed to obtain redshifts of galaxies in the fields of these quasars.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 106; 700; p. 646-669
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