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  • Other Sources  (9)
  • 1980-1984  (9)
  • 1
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    Thermal elastohydrodynamic lubrication of spur gears (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analysis and computer program called TELSGE were developed to predict the variations of dynamic load, surface temperature, and lubricant film thickness along the contacting path during the engagement of a pair of involute spur gears. The analysis of dynamic load includes the effect of gear inertia, the effect of load sharing of adjacent teeth, and the effect of variable tooth stiffness which are obtained by a finite-element method. Results obtained from TELSGE for the dynamic load distributions along the contacting path for various speeds of a pair of test gears show patterns similar to that observed experimentally. Effects of damping ratio, contact ratio, tip relief, and tooth error on the dynamic load were examined. In addition, two dimensionless charts are included for predicting the maximum equilibrium surface temperature, which can be used to estimate directly the lubricant film thickness based on well established EHD analysis.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-3241
    Format: application/pdf
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  • 2
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    A computer code for performance of spur gears (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In spur gears both performance and failure predictions are known to be strongly dependent on the variation of load, lubricant film thickness, and total flash or contact temperature of the contacting point as it moves along the contact path. The need of an accurate tool for predicting these variables has prompted the development of a computer code based on recent findings in EHL and on finite element methods. The analyses and some typical results which to illustrate effects of gear geometry, velocity, load, lubricant viscosity, and surface convective heat transfer coefficient on the performance of spur gears are analyzed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Research Center Advanced Power Transmission Technol.; p 503-518
    Format: application/pdf
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  • 3
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    Thermal Elastohydrodynamic Lubrication of Spur Gears (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Analysis and computer program (TELSGE) predict variations of dynamic load and surface temperature and lubricant film thickness along contacting path of pair of involute spur gears. Analysis of dynamic load includes effect of gear inertia, effect of load sharing of adjacent teeth, and effect of variable tooth stiffness obtained by element method. TELSGE written in FORTRAN IV.
    Keywords: MACHINERY
    Type: LEW-13528 , NASA Tech Briefs (ISSN 0145-319X); 7; 4; P. 454
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    High efficiency epitaxial GaAs/GaAs and GaAs/Ge solar cell technology using OM/CVD (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A technology for fabricating high efficiency, thin film GaAs solar cells on substrates appropriate for space and/or terrestrial applications was developed. The approach adopted utilizes organometallic chemical vapor deposition (OM-CVD) to form a GaAs layer epitaxially on a suitably prepared Ge epi-interlayer deposited on a substrate, especially a light weight silicon substrate which can lead to a 300 watt per kilogram array technology for space. The proposed cell structure is described. The GaAs epilayer growth on single crystal GaAs and Ge wafer substrates were investigated.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Resarch Center Space Photovoltaic Res. and Technol.; p 81-85
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  • 5
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    Ultra-Thin-Film GaAs Solar Cells (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Process based on organo-metallic chemical vapor deposition (OM/CVD) of trimethyl gallium with arsine forms economical ultrathin GaAs epitaxial films. Process has higher potential for low manufacturing cost and large-scale production compared with more-conventional halide CVD and liquid-phase epitaxy processes. By reducing thickness of GaAs and substituting low-cost substrate for single-crystal GaAs wafer, process would make GaAs solar cells commercially more attractive.
    Keywords: FABRICATION TECHNOLOGY
    Type: NPO-14930 , NASA Tech Briefs (ISSN 0145-319X); 6; 1; P. 108
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  • 6
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    Epitaxial thin film GaAs solar cells using OM-CVD techniques (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A new approach has been initiated at JPL to fabricate thin-film, high efficiency GaAs solar cells on low-cost, single-crystal Si substrates having a thin CVD interlayer of Ge to minimize the lattice and thermal expansion mismatch. For initial experiments, n(+)/p GaAs cells were grown by OM-CVD on single-crystal GaAs and Ge wafers. Details of the growths and performance results will be presented. Subsequently, a combined epitaxial structure of OM-CVD GaAs on a strongly adherent Ge interlayer on (100) Si was grown. This is the first report of the successful growth of this composite structure. Low module costs projected by JPL SAMICS methodology calculations and the potential for 400-600W/kg space solar arrays will be discussed.
    Keywords: SOLID-STATE PHYSICS
    Type: Photovoltaic Specialists Conference; May 12, 1981 - May 15, 1981; Kissimmee, FL
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  • 7
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    High efficiency thin-film GaAs solar cells (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper demonstrates the feasibility of producing high-efficiency GaAs solar cells with high power-to-weight ratios by organic metallic chemical vapor deposition (OM-CVD) growth of thin epi-layers on suitable substrates. An AM1 conversion efficiency of 18% (14% AM0), or 17% (13% AM0) with a 5% grid coverage is achieved for a single-crystal GaAs n(+)/p cell grown by OM-CVD on a Ge wafer. Thin GaAs epi-layers OM-CVD grown can be fabricated with good crystallographic quality using a Si-substrate on which a thin Ge epi-interlayer is first deposited by CVD from GeH4 and processed for improved surface morphology
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: In: Intersociety Energy Conversion Engineering Conference; Aug 09, 1981 - Aug 14, 1981; Atlanta, GA
    Format: text
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  • 8
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    Progress toward thin-film GaAs solar cells using a single-crystal Si substrate with a Ge interlayer (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Development of a technology for fabricating light-weight, high-efficiency, radiation-resistant solar cells for space applications is reported. The approaches currently adopted are to fabricate shallow homojunction n(+)/p as well as p/n AlGaAs-heteroface GaAs solar cells by organometallic chemical vapor deposition (OM-CVD) on single-crystal Si substrates using in each case, a thin Ge epi-interlayer first grown by CVD. This approach maintains the advantages of the low specific gravity of Si as well as the high efficiency and radiation-resistant properties of the GaAs solar cell which can lead to greatly improved specific power for a solar array. The growth of single-crystal GaAs epilayers on Ge epi-interlayers on Si substrates is investigated. Related solar cell fabrication is reviewed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1982: High Efficiency, Radiation Damage, and Blanket Technol.; p 99-104
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  • 9
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    Epitaxial and polycrystalline GaAs solar cells using OM-CVD techniques (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: GaAs epitaxial films were grown by chemical vapor deposition using organo-metallic sources (OM-CVD) on single crystal and polycrystalline bulk GaAs, as well as on bulk polycrystalline and recrystallized thin-film Ge substrates. Details of Antireflecting Metal-Oxide-Semiconductor (AMOS) solar cells fabricated on GaAs films grown on bulk polycrystalline Ge and recrystallized Ge thin-film substrates will be discussed, as well as preliminary photovoltaic results obtained for n(+)/p homojunction structures.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Photovoltaic Specialists Conference; Jan 07, 1980 - Jan 10, 1980; San Diego, CA
    Format: text
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