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  • AERODYNAMICS  (835)
  • ENERGY PRODUCTION AND CONVERSION  (558)
  • 1990-1994  (434)
  • 1980-1984  (959)
  • 1930-1934
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  • 1
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    Megawatt solar power systems for lunar surface operations (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The work presented here shows that a solar power system can provide power on the order of one megawatt to a lunar base with a fairly high specific power. The main drawback to using solar power is still the high mass, and therefore, cost of supplying energy storage through the solar night. The use of cryogenic reactant storage in a fuel cell system, however, greatly reduces the total system mass over conventional energy storage schemes.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: USRA, Proceedings of the 6th Annual Summer Conference: NASA(USRA University Advanced Design Program; p 229-239
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Applied aspects of laminar-flow technology (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An account is given of the development status and performance levels achieved with natural laminar flow (NLF), extended wing chord laminar flow control (LFC), and hybrid laminar flow control (HLFC) concepts combining NLF and partial-chord LFC in the leading-edge region. Attention is given to NLF wing structure construction methods capable of achieving the requisite surface-irregularity tolerances, LFC through wing surface suction slots or perforated skins, and the deleterious effects of insects, ice crystals, and noise disturbance inputs on the ability of NLF, LFC, and HLFC wings to maintain effective laminar flow operation.
    Keywords: AERODYNAMICS
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Low cost silicon-on-ceramic photovoltaic solar cells (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A technique has been developed for coating low-cost mullite-based refractory substrates with thin layers of solar cell quality silicon. The technique involves first carbonizing one surface of the ceramic and then contacting it with molten silicon. The silicon wets the carbonized surface and, under the proper thermal conditions, solidifies as a large-grained sheet. Solar cells produced from this composite silicon-on-ceramic material have exhibited total area conversion efficiencies of ten percent.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Status of diffused junction p+n InP solar cells for space applications (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Recently, we have succeeded in fabricating diffused junction p(sup +)n(Cd,S) InP solar cells with measured AMO, 25 C open circuit voltage (V(sub OC)) of 887.6 mV, which, to the best of our knowledge, is higher than previously reported V(sub OC) values for any InP homojunction solar cells. The experiment-based projected achievable efficiency of these cells using LEC grown substrates is 21.3 percent. The maximum AMO, 25 C internal losses due to date on bare cells is, however, only 13.2 percent. This is because of large external and internal losses due to non-optimized front grid design, antireflection (AR) coating and emitter thickness. This paper summarizes recent advances in the technology of fabrication of p(sup +)n InP diffused structures and solar cells, resulted from a study undertaken in an effort to increase the cell efficiency. The topics discussed in this paper include advances in: (1) the formation on thin p(sup +) InP:Cd emitter layers, (2) electroplated front contacts, (3) surface passivation and (4) the design of a new native oxide/Al2O3/MgF2 tree layer AR coating using a chemically-grown P-rich passivating oxide as a first layer. Based on the high radiation resistance and the excellent post-irradiation annealing and recovery demonstrated in the early tests done to date, as well as the projected high efficiency and low-cost high-volume fabricability, these cells show a very good potential for space photovoltaic applications.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Proceedings of the 13th Space Photovoltaic Research and Technology Conference (SPRAT 13); p 63-79
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    NASA TECHNICAL REPORTS
  • 5
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    Radiation hardness of Ga0.5In0.5 P/GaAs tandem solar cells (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The radiation hardness of a two-junction monolithic Ga sub 0.5 In sub 0.5 P/GaAs cell with tunnel junction interconnect was investigated. Related single junction cells were also studied to identify the origins of the radiation losses. The optimal design of the cell is discussed. The air mass efficiency of an optimized tandem cell after irradiation with 10(exp 15) cm (-2) 1 MeV electrons is estimated to be 20 percent using currently available technology.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center, Space Photovoltaic Research and Technology Conference; 7 p
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  • 6
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    Progress toward the development of dual junction GaAs/Ge solar cells (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Large area GaAs/Ge cells offer substantial promise for increasing the power output from existing silicon solar array designs and for providing an enabled technology for missions hitherto impossible using silicon. Single junction GaAs/Ge cells offer substantial advantages in both size, weight, and cost compared to GaAs cells but the efficiency is limited to approximately 19.2 to 20 percent AMO. The thermal absorptance of GaAs/Ge cells is also worse than GaAs/GaAs cells (0.88 vs 0.81 typ.) due to the absorption in the Ge substrate. On the other hand dual junction GaAs/Ge cells offer efficiencies up to ultimately 24 percent AMO in sizes up to 8 x 8 cm but there are still technological issues remaining to achieve current matching in the GaAs and Ge cells. This can be achieved through tuned antireflection (AR) coatings, improved quality of the GaAs growth, improved quality Ge wafers and the use of a Back Surface Field (BSF)/Back Surface Reflector (BSR) in the Ge cell. Although the temperature coefficients of efficiency and voltage are higher for dual junction GaAs/Ge cells, it has been shown elsewhere that for typical 28 C cell efficiencies of 22 percent (dual junction) vs 18.5 percent (single junction) there is a positive power tradeoff up to temperatures as high as 120 C. Due to the potential ease of fabrication of GaAs/Ge dual junction cells there is likely to be only a small cost differential compared to single junction cells.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA, Lewis Research Center, Space Photovoltaic Research and Technology, 1989; p 29-41
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    NASA TECHNICAL REPORTS
  • 7
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    A programmable heater control circuit for spacecraft (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Spacecraft thermal control is accomplished for many components through use of multilayer insulation systems, electrical heaters, and radiator systems. The heaters are commanded to maintain component temperatures within design specifications. The programmable heater control circuit (PHCC) was designed to obtain an effective and efficient means of spacecraft thermal control. The hybrid circuit provides use of control instrumentation as temperature data, available to the spacecraft central data system, reprogramming capability of the local microprocessor during the spacecraft's mission, and the elimination of significant spacecraft wiring. The hybrid integrated circuit has a temperature sensing and conditioning circuit, a microprocessor, and a heater power and control circuit. The device is miniature and housed in a volume which allows physical integration with the component to be controlled. Applications might include alternate battery-powered logic-circuit configurations. A prototype unit with appropriate physical and functional interfaces was procured for testing. The physical functionality and the feasibility of fabrication of the hybrid integrated circuit were successfully verified. The remaining work to develop a flight-qualified device includes fabrication and testing of a Mil-certified part. An option for completing the PHCC flight qualification testing is to enter into a joint venture with industry.
    Keywords: AERODYNAMICS
    Type: NASA-TM-108459 , NAS 1.15:108459
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    NASA TECHNICAL REPORTS
  • 8
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    Advanced technology exhaust nozzle development (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The requirement for greater tactical aircraft operational capabilities has led to increasing research emphasis on the refinement of engine/airframe integration methods and exhaust nozzle flexibility. A major prospective advancement in the development of these capabilities takes the form of multifunctional exhaust nozzle systems with thrust reversal and thrust vectoring features, whose operation will be shared by both airframe and powerplant control systems. Attention is presently given to the two-dimensional convergent-divergent and single expansion ramp nozzle designs, with emphasis on the variable geometry mechanical systems by which they assume cruising flight, vectoring, and thrust reversal operations. The nozzles have been wind tunnel model-tested for the cases of the F-18 fighter and a supersonic cruise configuration concept.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 83-1286
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Analysis of DSN software anomalies (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A categorized data base of software errors which were discovered during the various stages of development and operational use of the Deep Space Network DSN/Mark 3 System was developed. A study team identified several existing error classification schemes (taxonomies), prepared a detailed annotated bibliography of the error taxonomy literature, and produced a new classification scheme which was tuned to the DSN anomaly reporting system and encapsulated the work of others. Based upon the DSN/RCI error taxonomy, error data on approximately 1000 reported DSN/Mark 3 anomalies were analyzed, interpreted and classified. Next, error data are summarized and histograms were produced highlighting key tendencies.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-CR-164369 , JPL-9950-536 , RCI-TR-005 , LO-726925
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    NASA TECHNICAL REPORTS
  • 10
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    Photovoltaic applications - Past and future (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper presents an overview of photovoltaic systems applications since the initiation of the U.S. National Photovoltaic Program in 1975. Experiences with these applications are summarized and some conclusions are drawn. Implications for future research, technology development and application experiments are drawn from the experiences to date.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Photovoltaic Specialists Conference; Jan 07, 1980 - Jan 10, 1980; San Diego, CA
    Format: text
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