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  • Other Sources  (584)
  • NASA Technical Reports  (584)
  • ENERGY PRODUCTION AND CONVERSION  (385)
  • METALLIC MATERIALS  (191)
  • Man/System Technology and Life Support
  • 2010-2014
  • 1980-1984  (584)
  • 1925-1929
  • 1984  (584)
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  • Other Sources  (584)
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  • NASA Technical Reports  (584)
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  • 2010-2014
  • 1980-1984  (584)
  • 1925-1929
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  • 1
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    Tomato growth as affected by root-zone temperature and the addition of gibberellic acid and kinetin to nutrient solutions (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The effect of root-zone temperature on young tomato plants (Lycopersicon esculentum Mill. cv. Heinz 1350) was evaluated in controlled environments using a recirculating solution culture system. Growth rates were measured at root-zone temperatures of 15 degrees, 20 degrees, 25 degrees, and 30 degrees C in a near optimum foliar environment. Optimum growth occurred at 25 degrees to 30 degrees during the first 4 weeks of growth and 20 degrees to 25 degrees during the 5th and 6th weeks. Growth was severely restricted at 15 degrees. Four concentrations of gibberellic acid (GA3) and kinetin were added to the nutrient solution in a separate trial; root-zone temperature was maintained at 15 degrees and 25 degrees. Addition of 15 micromoles GA3 to solutions increased specific leaf area, total leaf area, and dry weight production of plants in both temperature treatments. GA3-induced growth stimulation was greater at 15 degrees than at 25 degrees. GA3 may promote growth by increasing leaf area, enhancing photosynthesis per unit leaf area, or both. Kinetic was not useful in promoting growth at either temperature.
    Keywords: Man/System Technology and Life Support
    Type: Journal of the American Society for Horticultural Science. American Society for Horticultural Science (ISSN 0003-1062); Volume 109; 1; 121-5
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  • 2
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    Fatigue induced cracking in aluminum LN-2 shroud of 39 foot vacuum chamber (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Fourteen years after completion of Ford's 39-foot space simulation chamber, leaks began to appear in its LN2 shroud. Although the shroud had been tight since its acceptance, cracks appeared in 1983 in some of the field welds of the one inch tubes which interconnect the LN2 panels. The resulting leaks were large enough to prevent pump down to high vacuum and could be heard easily when the chamber was at ambient conditions. New cracks appeared during each thermal cycle making it impossible to utilize the chamber for thermal vacuum testing. The analysis presented here implies that many, if not all, of the aluminum LN2 shrouds now in use may be in various stages of fatigue failure. The probability is high that fatigue cracks are working through the aluminum tubing in heat-affected zones of some field welds. The cracks may not be apparent yet, but after the shroud has experienced a certain number of thermal cycles these cracks will work through the material and become serious leaks. Fortunately, appropriate planning, analysis, and checking can, with a relatively small expenditure of money, help to avoid large and unexpected shroud failures and keep the chamber operational as long as it is needed.
    Keywords: METALLIC MATERIALS
    Type: NASA. Goddard Space Flight Center 13th Space Simulation Conf.; p 77-100
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  • 3
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    High speed, low cost, LEO-thermal-cycling facility (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The design and operations of a low cost, high rate thermal cycling facility designed for LEO conditions is described. Thermal cycling facilities were constructed with various design criteria. Some were designed to duplicate as closely as possible the conditions a cell or module would encounter while in orbit about the Earth. A typical facility to perform this type of cycling was a large vacuum system with liquid nitrogen cooled walls. The cells were heated by an AMO spectrum solar simulator, then a shutter was closed allowing the cells to give up their heat to the cold walls. This system was good at duplicating the orbital conditions but was slow and very costly to operate. Other systems used a gas atmosphere and heated the cells with radiant heat and cooled the cells by moving them into close proximity to a cold plate. The systems greatly increased the cycle times. Other systems moved the heating and cooling atmosphere into and out of the test areas and achieved reasonable cycle rates. All these systems, however, are expensive to operate.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Space Photovoltaic Res. and Technol. 1983; p 223-227
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  • 4
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    Panel fabrication utilizing GaAs solar cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The development of the GaAs solar cells for space applications is described. The activities in the fabrication of GaAs solar panels are outlined. Panels were fabricated while introducing improved quality control, soldering laydown and testing procedures. These panels include LIPS II, San Marco Satellite, and a low concentration panel for Rockwells' evaluation. The panels and their present status are discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 205-209
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  • 5
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    Preflight study of San Marco D/L GaAs solar cell panels (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The solar array for the San Marco D/L spacecraft is described and the performance of 4 GaAs solar cell panels are examined. In comparison to the typical Si solar cell panel for San Marco D/L, it is shown that each GaAs solar cell panel provides at least 23 percent more specific power at maximum output and 28 deg C. Also described here, are several measurements that will be made to evaluate the relative performance of Si and GaAs solar cell panels during the San Marco D/L flight.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 176-181
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  • 6
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    Development of GaAs/Si and GaAs/Si monolithic structures for future space solar cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The results of heteroepitaxial growth of GaAs and GaAlAs directly on Si are presented, and applications to new cell structures are suggested. The novel feature is the elimination of a Ge lattice transition region. This feature not only reduces the cost of substrate preparation, but also makes possible the fabrication of high efficiency monolithic cascade structures. All films to be discussed were grown by organometallic chemical vapor deposition at atmospheric pressure. This process yielded reproducible, large-area films of GaAs, grown directly on Si, that are tightly adherent and smooth, and are characterized by a defect density of 5 x 10(6) power/sq cm. Preliminary studies indicate that GaAlAs can also be grown in this way. A number of promising applications are suggested. Certainly these substrates are ideal for low-weight GaAs space solar ells. For very high efficiency, the absence of Ge makes the technology attractive for GaAlAs/Si monolithic cascades, in which the Si substrates would first be provided with a suitable p/n junction. An evaluation of a three bandgap cascade consisting of appropriately designed GaAlAs/GaAs/Si layers is also presented.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 128-139
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  • 7
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    Defect studies in one MeV electron irradiated GaAs and in Al/sub x Ga/sub l-x As P-N junction solar cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Deep level transient spectroscopy reveals that the main electron traps for one-MeV electron irradiated GaAs cells are E9c)-0.31, E(c)-0.90 eV, and the main hole trap is due to the level. Electron trap density was found to vary from 3/tens-trillion ccm for 2/one quadrillion cm 3/3.7 quadrillion cm for 21 sextillion cm electron fluence for electron fluence; a similar result was also obtained for the hole trap density. As for the grown-in defects in the Al(x)Ga(1-x)As p-n junciton cells, only two electron traps with energies of E(c)-0.20 and E(c)-0.34 eV were observed in samples with x = 0.17, and none was found for x 0.05. Auger analysis on the Al(x)Ga(1-x) As window layer of the GaAs solar cell showed a large amount of oxygen and carbon contaminants near the surface of the AlGaAs epilayer. Thermal annealing experiment performed at 250 C for up to 100 min. showed a reduction in the density of both electron traps.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 91-101
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  • 8
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    Model of solar cell proton damage (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A short circuit current (I sub sc) degradation model for gallium arsenide (GaAs) solar cells irradiated by protons from low energy to 100 MeV was developed. This model was found to be satisfactory in predicting the I sub sc degradation of GaAs cells, but not that of silicon (Si) cells. A modification to the aforementioned model that preserves the optical wavelength dependency in the photogeneration of minority carrier pairs was described herein. Spectral Si and GaAs response and I sub sc for the Si and GaAs solar cells were discussed, and also were presented in graph form. The overall predictability of the modified model was deemed to be satisfactory.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 56-62
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  • 9
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    Process in manufacturing high efficiency AlGaAs/GaAs solar cells by MO-CVD (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Manufacturing technology for mass producing high efficiency GaAs solar cells is discussed. A progress using a high throughput MO-CVD reactor to produce high efficiency GaAs solar cells is discussed. Thickness and doping concentration uniformity of metal oxide chemical vapor deposition (MO-CVD) GaAs and AlGaAs layer growth are discussed. In addition, new tooling designs are given which increase the throughput of solar cell processing. To date, 2cm x 2cm AlGaAs/GaAs solar cells with efficiency up to 16.5% were produced. In order to meet throughput goals for mass producing GaAs solar cells, a large MO-CVD system (Cambridge Instrument Model MR-200) with a susceptor which was initially capable of processing 20 wafers (up to 75 mm diameter) during a single growth run was installed. In the MR-200, the sequencing of the gases and the heating power are controlled by a microprocessor-based programmable control console. Hence, operator errors can be reduced, leading to a more reproducible production sequence.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 18-24
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  • 10
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    Thin metal film and multilayers experiment (A0138-3) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The sources of degradation of in state of the art and newly developed components and testing the usefulness of the concept of storing experiment samples in dry nitrogen under launch and space vacuum conditions during reentry mission phase were investigated. Ultraviolet (UV) and extreme ultraviolet (EUV) experiments suffer degradations during space missions of even 1 month duration. It is suggested that the degradation is due to condensation of outgassing products, followed by solar induced polymerization, however, penetrating charged particles are also known to produce volume effects. Degradation may also start immediately after manufacturing of the component due to oxidation, moisture, or chemical corrosion by atmospheric constituents such as CO2 and SO2. When the filters are used as windows for gas absorption cells or gas filters, or when they define the instrumental bandwidth by themselves. The effects of mechanical degradation by thermal cycling and/or dust may cause a dramatic impact.
    Keywords: METALLIC MATERIALS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 159-160
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  • 11
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    Investigation of critical surface degradation effects on coatings and solar cells developed in Germany (S1002) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Various coatings developed in the FRG (i.e., second-surface mirrors with interference filters with and without conductive layers, conductive layers on solar-cell covers, and selective absorber coatings) have been qualified by accelerated tests under simulated space environment conditions. Experiments with coatings and solar cells have shown, however, that the thermo-optical behavior can differ considerably when performed on the ground and in space because of the great difficulty in simulating the space environment realistically. The objective of this experiment is to qualify these coatings under realistic space environment conditions. In addition, the experiment will provide design criteria, techniques, and test methods to insure control of the combined space and spacecraft environment effects, such as contamination, electrical conductance, and optical degradation, on the coatings. Data to be measured include the temperature of the samples, the electrical resistance of the conductive layers of the samples, the short circuit current of the solar-cell modules, and the deposition of contaminants on the samples (using quartz crystal microbalances (QCM's)).
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 91-93
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  • 12
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    Solar-array-materials passive LDEF experiment (A0171) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objective of this experiment is to evaluate the synergistic effects of the space environment on various solar-array materials, including solar cells, cover slips with various antireflectance coatings, adhesive, encapsulants, reflector materials, substrate strength materials, mast and harness materials, structural composites, and thermal control treatments. The experiment is passive and consists of an arrangement of material specimens mounted in a 3-in.-deep peripheral tray. The effects of the space environment on the specimens will be determined by comparison of preflight and postflight measurements of mechanical, electrical, and optical properties.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 86-87
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  • 13
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    A review of our present understanding of macrosegregation in ingots (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: The present understanding of the mechanisms responsible for macrosegregation occurring in ingots produced by electroslag remelting (ESR), vacuum arc remelting (VAR), direct chill (DC), and continuous casting is reviewed. A detailed description is given of laboratory experiments on model Sn-Pb and Al-Cu alloys. The experimental findings are compared with theoretical predictions. Data are also presented on a high-temperature Ni-27 wt % Mo alloy ESR ingot and 2000 series aluminum alloy DC ingots. Comparison is made to theoretical predictions where appropriate.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 169-186
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  • 14
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    Macrosegregation in aluminum alloy ingot cast by the semicontinuous direct chill method (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: A theoretical model of the semicontinuous DC casting method is developed to predict the positive segregation observed at the subsurface and the negative segregation commonly found at the center of large commercial-size aluminum alloy ingot. Qualitative analysis of commercial-size aluminum alloy semicontinuous cast direct chill (DC) ingot is carried out. In the analysis, both positive segregation in the ingot subsurface and negative segregation at the center of the ingot are examined. Ingot subsurface macrosegregation is investigated by considering steady state casting of a circular cross-section binary alloy ingot. Nonequilibrium solidification is assumed with no solid diffusion, constant equilibrium partition ratio, and constant solid density.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 157-168
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  • 15
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    Solidification structures grown under induced flow and continuous casting of steel (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: The use of induced flow as a means to control solidification structures in strand cast steel is investigated. The quality problems in strand cast steel stemming from columnar growth can be partially controlled, by Electro Magnetic Stirring (EMS). Induced flow changes the normal morphology of dendrites. Solids grown under intense stirring conditions show both negative and positive segregation which is considered unacceptable by some steel producers. The inclusion size and population is strongly affected by induced flow (EMS). Laboratory and industrial data show substantial reduction in inclusion size and content, but the overall effect of flow on inclusions is affected by the particular type of flow patterns utilized in each case. Productivity and quality are raised substantially in steel strand casting by utilizing EMS.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 151-156
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  • 16
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    Microsegregation during directional solidification (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: During the directional solidification of alloys, solute inhomogeneities transverse to the growth direction arise due to morphological instabilities (leading to cellular or dendritic growth) and/or due to convection in the melt. In the absence of convection, the conditions for the onset of morphological instability are given by the linear stability analysis of Mullins and Sekerka. For ordinary solidification rates, the predictions of linear stability analysis are similar to the constitutional supercooling criterion. However, at very rapid solidification rates, linear stability analysis predicts a vast increase in stabilization in comparison to constitutional supercooling.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 117-138
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  • 17
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    Characterization of macrosegregation in ESR IN-718 (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: Aspects of macrosegregation theory, such as dendrite arm spacing, pool profile and mushy zone depth are beneficial to developing consumable melting process for Ion Nickel IN-718, Electro-Slag Refining, especially ESR. Aspects of microsegregation theory, such as correlation of dendrite arm spacing with heat transfer mechanisms and local solidification time, are used to minimize remnant dendritism in both ESR and Vacuum Arc Remelting VAR IN-718. Specifically, ESR IN-718 must be optimized by developing practices which maximize ingot cooling rate and minimize the steepness of the solidus and liquidus isotherms. The knowledge concerning macrosegregation in consumable melted IN-718 is in the form of correlations. Since the isotherm steepness is undoubtedly involved, investigations which include a microgravity environment might separate microsegregation effects from macrosegregation effects. Accounting for the effects of gravity and density differences between the metal pool and the interdendritic fluid, in combination with the pool and mushy zone profiles, can lead to improved melting solidification practices for IN-718, and allow prediction of macrosegregation tendency to be incorporated into high temperature alloy design.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 139-150
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  • 18
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    Changes in solidified microstructures (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: The properties and casting behavior of metals are significantly affected by their cast structure. This structure is optimized by producing columnar versus equiaxed grains and coarse versus fine grains by controlling solidification conditions. The transition from columnar to equiaxed grains is favored by: constitutional supercooling with effective nucleation of free dendrites; melting off and transport of dendrite tips and arms; mechanical vibration; falling down of free dendrites from a chilled top surface; and induced flow in the solidifying structure by oscillation of rotation.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 91-104
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  • 19
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    Porosity and environment (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: Significant progress was achieved when it was realized that porosity could be analyzed successfully by considering not only heat flow, but also fluid flow within the solidifying casting. Sound castings may be produced by lowering pressure during melting (to allow dissolved gas to escape the melt) and increasing pressure during solidification (to force liquid metal into the mushy zone to feed shrinkage). Such techniques are especially effective if they are combined with chilling of parts of the casting to produce progressive solidification, which shortens the mushy zone and, hence, the distance that metal must travel to feed porosity.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 71-78
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  • 20
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    The movement of particles in liquid metals under gravity forces and the interaction of particles with advancing solid-liquid interface (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: The problems of shrinkage and gas porosity are discussed. Gravity forces enhance the removal of gas bubbles from a metal melt and contribute to the feeding of shrinkage porosity in castings. Experiments are reviewed which determine how large a density difference is required for metal particles to float or sink in a metal melt and to what extent do factors not considered in Stokes Law influence particle movement in a real system. As to the interaction of particles with an advancing solid-liquid interface, the results indicate that the metal particles are not rejected in a metal melt, and that concentrations of particles in a metal following solidification are due to other factors.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 79-90
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  • 21
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    The potential for bulk undercooling as an industrial process (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: The main focus is on solidification occurring in highly supercooled melts. Solidification rates in such melts are extremely high, an attractive feature from a commercial standpoint. Thus, the reported growth velocities for pure Ni and Co dendrites at a supercooling of 175 K are in excess of 180 km/hr. Rapidly quenched crystalline alloys produced by various atomization processes (e.g., centrifugal atomization or inert gas atomization) or melt spinning are examples of solidification processes, currently being intensively explored commercially, wherein extremely high solidification rates are achieved. Estimated dendrite tip growth rates are about 2 km/hr in a binary Al-4.5 wt % alloy, with a heat transfer coefficient of 6.4x10 sub 5 w/sq cm K or 15 cal/cu cm sK. In the limit, when the solidification rate exceeds a critical value, a glassy microstructure is obtained even in highly alloyed melts, which under normal conditions would solidity to form one or more crystalline phases. Glassy metals, also called metallic glasses, are candidate materials for distribution transformers because of their very low energy losses and are also being used in brazing and soldering applications.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 33-70
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  • 22
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    Bulk undercooling (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: Bulk undercooling methods and procedures will first be reviewed. Measurement of various parameters which are necessary to understand the solidification mechanism during and after recalescence will be discussed. During recalescence of levitated, glass-encased large droplets (5 to 8 mm diam) high speed temperature sensing devices coupled with a rapid response oscilloscope are now being used at MIT to measure local thermal behavior in hypoeutectic and eutectic binary Ni-Sn alloys. Dendrite tip velocities were measured by various investigators using thermal sensors or high speed cinematography. The confirmation of the validity of solidification models of bulk-undercooled melts is made difficult by the fineness of the final microstructure, the ultra-rapid evolution of the solidifying system which makes measurements very awkward, and the continuous modification of the microstructure which formed during recalescence because of precipitation, remelting and rapid coarsening.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 15-32
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  • 23
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    The undercooling of liquids (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: The formation by melt quenching of such metastable structures as glassy or microcrystalline solids and highly supersaturated solutions is made possible by the extreme resistance of most melts to homophase crystal nucleation at deep undercooling. This nucleation resistance contrasts sharply with the very low kinetic resistance to the movement of crystal-melt interfaces, once formed, in metals and other fluid systems at even minute undercooling. The methods of nucleation study which have proven especially effective in bypassing nucleation by heterophase impurities thereby exposing the high resistance of melts to homophase nucleation may be summarized as follows: observation of the crystallization behavior of dispersed small droplets; drop tube experiments in which liquid drops solidify, under containerless conditions, during their fall in the tube; and observation of the crystallization of bulk specimens immersed in fluxes chosen to dissolve or otherwise deactivate (e.g., by wetting) heterophase nucleants. This method has proven to be remarkably effective in deactivating such nucleants in certain pure metals.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 11-14
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  • 24
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    Solidification study of some Ni- and Co-base alloys (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: An ongoing research program aims to characterize the solidification of several Ni- and Co-based commercial wrought type alloys. The techniques used and the data items sought are: (1) thermal analysis, liquidus, nonequilibrium solidus as a function of cooling rate, secondary reactions temperatures, incipient melting, progress of solidification as a function of temperature; (2) optical metallography, characteristic structures and secondary dendrite arm spacing as a function of cooling rate; (3) X-ray diffraction, identification of precipitates; and (4) SEM/EDAX, measure of microsegregation.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 105-116
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  • 25
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    Low concentration ratio solar array structural configuration (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-03
    Description: The design and structural properties of a low concentration ratio solar array are discussed. The assembled module consists of six interconnected containers which are compactly stowed in a volume of 3.24 m(3) for delivery to orbit by the shuttle. The containers deploy in accordian fashion into a rectangular area of 19.4 x 68 meters and can be attached to the user spacecraft along the longitudinal centerline of the end container housing. Five rotary incremental actuators requiring about 8 watts each will execute the 180-degree rotation at each joint. Deployable masts (three per side) are used to extend endcaps from the housing in both directions. Each direction is extended by three masts requiring about 780 watts for about 27 minutes. Concentrator elements are extended by the endcaps and are supported by cable systems that are connected between the housings and endcaps. These power generating elements contain reflector panels which concentrate light onto the solar panels consisting of an aluminum radiator with solar cells positioned within the element base formed by the reflectors. A flat wire harness collects the power output of individual elements for transfer to the module container housing harnesses.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center STEP Expt. Requirements; p 185-198
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  • 26
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    High-efficiency Conventional Cells Workshop (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Participants expressed more interest in GaAs cells than in Si cells. For silicon cells, the beginning of life efficiency is not a major problem but more research is needed in the end of life efficiency. The beginning of life efficiency of GaAs cells must be brought up to 20% at AMO. More proton damage tests must be conducted. Liquid phase epitaxy technology is current but chemical vapor deposition technology is more flexible. There are no obvious problems in limiting process yields. Technology transfer should occur when market demands are generated.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 251-252
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    Transparent arrays: Progress toward higher efficiency (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Principles and design considerations of IR transparent solar arrays are discussed. Optimization of performance of flexible solar arrays was studied. Measured solar absorptance as low as alpha s = 0.59 was achieved which leads to a predicted BOL power density of 182.7 = W/square meters. Advanced array concepts, system level cascaded panels, and transparent rigid panels are proposed and expected benefits discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 210-219
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  • 28
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    Development and support structures for high-power solar arrays (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A number of structurally efficient configurations for wing-type solar arrays are developed by a combination of deepening the planform of the blanket and structure and by partitioning the blanket with battens and frequent attachments to the support structure. This technique reduces the tension required to avoid a low natural frequency for the blanket, and the load reduction results in a lighter structure. The use of three different structures are investigated: the Astromast, the Extendible Support Structure (ESS), and a new beam called the STACBEAM (Stacking Triangular Articulated Compact Beam) and their relative performances are compared. The investigation of the STACBEAM is emphasized because its sequential deployment is more reliable for very long systems, and its linear deployment facilitates local attachments to the blanket and the development of a low mass deployer.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 193-204
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  • 29
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    Preliminary space station solar array structural design study (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Structurally efficient ways to support the large solar arrays (3,716 square meters which are currently considered for space station use) are examined. An erectable truss concept is presented for the on orbit construction of winged solar arrays. The means for future growth, maintenance, and repair are integrally designed into this concept. Results from parametric studies, which highlight the physical and structural differences between various configuration options are presented. Consideration is given to both solar blanket and hard panel arrays.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 182-192
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  • 30
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    Preliminary concept of a 100-kilowatt miniaturized Cassegrainian concentrator solar array (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A miniaturized Cassegrainian concentrator (MCC) solar array system is examined to assess the practicality of assembling the basic MCC element into a total array system capable of producing multi-hundred kilowatts of power for Space Platform/Space Station or other low Earth orbit long lifetime missions. Preliminary mechanical and electrical subsystems are developed in order to determine first order performance characteristics. Results of the study support the feasibility of a 100-kilowatt MCC array system with beginning-of-life (BOL) performance of 160 watts per square meter and 28 W/kg. The performance numbers are based on 20 percent efficient (at operating temperature) solar cells and 0.25-millimeter thick electroformed nickel optics. These performance numbers can be improved upon significantly with the development of higher efficiency solar cells and/or lighter weight optics.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 157-162
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  • 31
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    High-efficiency solar cells fabricated by vacuum MO-CVD (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: High-efficiency, monolithic, two-color, three-terminal solar cells were fabricated by a novel growth technique, vacuum metal-organic chemical vapor deposition. The technique uses the expensive metal alkyls efficiently and toxic gases sparingly. The fact that the outer chamber is constructed of nonbreakable stainless steel is an attractive safety feature associated with this deposition system.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 148-154
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  • 32
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    Optimal design of high-efficiency single-junction and tandem concentrator space cells at 80 deg C and 100 SUNS (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Computer analysis was used to determine the AMO conversion efficiency of single-junction crystalline cells, two-cell and three-cell crystalline tandem structures operating under 100 suns and at 80 C. For optimally designed devices, the calculated efficiencies are 24% for single-junction cells, 33 to 35% for two-cell tandem structures, and 37 to 39% for three-cell tandem structures. Practical efficiencies are expected to be about 15 relative percentage points lower in each case.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 120-127
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  • 33
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    Equivalent electron fluence for solar proton damage in GaAs shallow junction cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The short-circuit current reduction in GaAs shallow junction heteroface solar cells was calculated according to a simplified solar cell damage model in which the nonuniformity of the damage as a function of penetration depth is treated explicitly. Although the equivalent electron fluence was not uniquely defined for low-energy monoenergetic proton exposure, an equivalent electron fluence is found for proton spectra characteristic of the space environment. The equivalent electron fluence ratio was calculated for a typical large solar flare event for which the proton spectrum is PHI(sub p)(E) = A/E(p/sq. cm) where E is in MeV. The equivalent fluence ratio is a function of the cover glass shield thickness or the corresponding cutoff energy E(sub c). In terms of the cutoff energy, the equivalent 1 MeV electron fluence ratio is r(sub p)(E sub c) = 10(9)/E(sub c)(1.8) where E(sub c) is in units of KeV.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 112-117
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  • 34
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    Cell and defect behavior in lithium-counterdoped solar cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Some n(+)/p cells in which lithium is introduced as a counterdopant, by ion-implantation, into the cell's boron-doped p-region were studied. To determine if the cells radiation resistance could be significantly improved by lithium counterdoping. Defect behavior was related to cell performance using deep level transient spectroscopy. Results indicate a significantly increased radiation resistance for the lithium counterdoped cells when compared to the boron doped 1 ohm-cm control cell. The increased radiation resistance of the lithium counterdoped cells is due to the complexing of lithium with divacancies and boron. It is speculated that complexing with oxygen and single vacancies also contributes to the increased radiation resistance. Counterdoping silicon with lithium results in a different set of defects.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Space Photovoltaic Res. and Technol. 1983; p 102-110
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  • 35
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    On-orbit performance of LIPS gallium arsenide solar cell experiment (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Telemetry from the Living Plume Shield's gallium arsenide solar panel experiment was evaluated to determine degradation. The data were culled to preclude spurious results from possible shadowing or inaccurate measurements on a cold array. Two independent methods were then used to obtain the maximum power points and the various characteristics of the solar array. Fill factor, open circuit voltage, short circuit current, and series and shunt resistances were examined. The data analysis concluded that, to date, nearly all of the solar array degradation is due to the reduction in the short circuit current.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 81-89
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  • 36
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    Radiation tolerance of low resistivity, high voltage silicon solar cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The radiation tolerance of the following three low resistivity, high voltage silicon solar cells was investigated: (1) the COMSAT MSD (multi-step diffused) cell, (2) the MinMIS cell, and (3) the MIND cell. A description of these solar cells is given along with drawings of their configurations. The diffusion length damage coefficients for the cells were calculated and presented. Solar cell spectral response was also discussed. Cells of the MinMIS type were judged to be unsuitable for use in the space radiation environment.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Space Photovoltaic Res. and Technol. 1983; p 74-80
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  • 37
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    Piecewise simulaton proton test of gallium arsenide and thin silicon solar cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Gallium Arsenide (GaAs) solar cells are viewed as a potential primary power source on certain future Earth orbiting satellites. However, the relative merits of gallium arsenide over silicon in a space radiation environment are largely unknown because a general degradation model for gallium arsenide does not exist. The results of a test simulating the proton radiation environment existing in a polar orbit and the concomitant effects on GaAs and thin silicon (Si) solar cells are presented. The objectives and methodology of the simulation test were discussed. The electrical characteristics of GaAs and Si solar cells are given in graph form. It was concluded that GaAs cells are viable for use on satellites in low Earth orbit.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 63-73
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  • 38
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    Solar cell degradation in proton radiation orbits (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Significant discrepancies have been observed between predicted and actual in-orbit silicon solar array degradation in orbits other than LEO (low Earth orbits) and GEO (geosynchronous orbit). These discrepancies have been diagnosed to arise probably from a combination of a lack of appropriate solar cell test data and from inadequacies in the models that relate the unidirectional and mono-energetic proton test data to the omnidirectional flux-energy spectra actually found in orbit. Relative damage coefficients and solar cell power outputs were discussed, and also were presented in graph form. Silicon and gallium arsenide solar cells were considered.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 49-55
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  • 39
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    Radiation testing of GaAs on CRRES and LIPS experiment (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The radiation damage of solar cells has become a prime concern to the U.S. Air Force due to longer satellite lifetime requirements. Flight experiments were undertaken on the Navy Living Plume Shield (LPS) satellite and the NASA/Air Force Combined Release and Radiation Effects Satellite (CRRES) to complement existing radiation testing. Each experiment, the rationale behind it, and its approach and status are presented. The effect of space radiation on gallium arsenide (GaAs) solar cells was the central parameter investigated. Specifications of the GaAs solar cells are given.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 41-48
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  • 40
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    Two-dimensional computer simulation of EMVJ and grating solar cells under AMO illumination (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A computer program, SCAP2D (Solar Cell Analysis Program in 2-Dimensions), is used to evaluate the Etched Multiple Vertical Junction (EMVJ) and grating solar cells. The aim is to demonstrate how SCAP2D can be used to evaluate cell designs. The cell designs studied are by no means optimal designs. The SCAP2D program solves the three coupled, nonlinear partial differential equations, Poisson's Equation and the hole and electron continuity equations, simultaneously in two-dimensions using finite differences to discretize the equations and Newton's Method to linearize them. The variables solved for are the electrostatic potential and the hole and electron concentrations. Each linear system of equations is solved directly by Gaussian Elimination. Convergence of the Newton Iteration is assumed when the largest correction to the electrostatic potential or hole or electron quasi-potential is less than some predetermined error. A typical problem involves 2000 nodes with a Jacobi matrix of order 6000 and a bandwidth of 243.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 34-40
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  • 41
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    Recent advances in LPE GaAs-based solar cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Several modifications were made to an infinite solution liquid phase epitaxy system that help fabricate both GaAs-based cells and thin cells that effectively reduce power-to-weight ratio for space applications. The most important development is the multiwell crucible for multilayer growth. Using a split crucible in one system, as many as five layers were grown in succession with varying Al levels and dopants. The structures grown were used to produce thin GaAs cells only 10 to 20 microns thick and also to grow cascade cell components. Results of these studies are presented and their applications to the future development of GaAs-based cells are discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 12-17
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  • 42
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    Structurally stable, thin silicon solar cells (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A fabrication process for structurally stable thin solar cell wafers that produce good power output after irradiation is described. The fabrication process is as follows. A 6 mil, circular wafer is oxidized on both sides. One side is then patterned with a rectangular array of holes in the oxide that are nominally 75 mils square and separated by 2 mil spacings. Wells are then etched into the silicon with KOH to a depth of 4 mils, leaving a 2 mil, unetched thickness. Two areas on the surface are left unetched to provide pads for bonding or testing. All oxide is then removed and the rest of the processing is normal; the unetched face is used as the illuminated face. When all other processing is complete, a 2 X 2 cm cell is sawed from the starting wafer leaving a border that is approximately 10 mils wide. The effective thickness, determined by weighing an unmetallized sample, of such a cell is about 2.4 mil.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 8-11
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  • 43
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    Advanced photovoltaic experiment (S0014) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The advanced photovoltaics-related experiments for investigating a portion of the solar spectrum and the effect of the space environment on photovoltaics. The information will be used to provide correlation between space and ground testing and also to provide for more accurate performance measurement in the laboratory. Specific objectives of these experiments are to provide information on the performance and endurance of advanced and conventional solar cells, to improve reference standards for photovoltaic measurements, and to measure the energy distribution in the extraterrestrial solar spectrum. Data to be obtained will include temperatures and short-circuit current of the samples. Six-point current-voltage (I-V) characteristics will be obtained for selected samples. These data will be recorded once a day during the flight. Orbit data will be correlated with preflight and postflight measurement of the samples.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 88-90
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  • 44
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    Microwelding of various metallic materials under ultravacuum (A0138-10) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: In the space vacuum environment, the spacecraft mechanisms are liable to sustain damaging effects from microwelds due to molecular diffusion of the spacecraft constituent metals. Such microwelds result in a continuing increase in the friction factors and are even liable to jam the mechanisms altogether. The object of this experiment is to check the metal surfaces representative of the mechanism constituent metals (treated or untreated, lubricated or unlubricated) for microwelds afater an extended stay in the space environment. The experimental approach is to passively expose inert metal specimens to the space vacuum and to conduct end-of-mission verification of the significance of microwelds between various pairs of metal washers. The experiment will be located in one of the FRECOPA boxes in a 12-in. -deep peripheral tray that contains nine other experiments from France.
    Keywords: METALLIC MATERIALS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 35-37
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  • 45
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    Report of the Panel on Human Factors (1984)
    In:  CASI
    Details
    Publication Date: 2005-06-30
    Description: Human error in the operation of complex systems is the largest single cause of incidents, accidents, and the loss of lives and dollars. Therefore, it is understandable that the focus of human factors research and engineering is on increasing our understanding of the basic mechanisms of human error and on developing techniques for reducing or eliminating the various causes of human error.
    Keywords: Man/System Technology and Life Support
    Type: Aeronautics Technology Possibilities for 2000: Report of a Workshop; 177-194; NASA-CR-205283
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  • 46
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    Power Sources Symposium, 31st, Atlantic City, NJ, June 11-14, 1984, Proceedings (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The present conference on electrochemical power sources encompasses systems of such types as the thermoelectric, advanced rechargeable, lithium reserve, rechargeable, and nonrechargeable, nickel-cadmium and nickel-hydrogen rechargeable, lead-acid, nickel-zinc and nickel-iron rechargeable, nickel-cadmium and nickel-hydrogen rechargeable, and fuel cells. Attention is given to Si-Ge alloy multicouple technology, sodium-sulfur battery development status, the safety aspects of a rechargeable lithium C cell, fiber-structure electrodes for nickel-cadmium batteries, energy density improvements in Li/carbon monofluoride cells, zinc-air button cell technology, catalyzed cathodes for Li/SOCl2 cells, the effect of polymer structure on the rate capability of the lithium-iodine cell, and a methanol fuel cell powerplant.
    Keywords: ENERGY PRODUCTION AND CONVERSION
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  • 47
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    Hydrogen from renewable energy - Photovoltaic/water electrolysis as an exemplary approach (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A feasibility study has been conducted for a NASA Kennedy Space Center liquid hydrogen/liquid oxygen production facility using solar cell arrays as the power source for electrolysis. The 100 MW output of the facility would be split into 67.6 and 32 MW portions for electrolysis and liquefaction, respectively. The solar cell array would cover 1.65 sq miles, and would be made up of 249 modular 400-kW arrays. Hydrogen and oxygen are generated at either dispersed or centralized water electrolyzers. The yearly hydrogen output is projected to be 5.76 million lbs, with 8 times that much oxygen; these fuel volumes can support approximately 18 Space Shuttle launches/year.
    Keywords: ENERGY PRODUCTION AND CONVERSION
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  • 48
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    Reflectance of metallic indium for solar energy applications (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An investigation has been conducted in order to compile quantitative data on the reflective properties of metallic indium. The fabricated samples were of sufficiently high quality that differences from similar second-surface silvered mirrors were not apparent to the human eye. Three second-surface mirror samples were prepared by means of vacuum deposition techniques, yielding indium thicknesses of approximately 1000 A. Both hemispherical and specular measurements were made. It is concluded that metallic indium possesses a sufficiently high specular reflectance to be potentially useful in many solar energy applications.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Energy (ISSN 0038-092X); 32; 2, 19; 311
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  • 49
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    Increased radiation resistance in lithium-counterdoped silicon solar cells (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Lithium-counterdoped n(+)p silicon solar cells are found to exhibit significantly increased radiation resistance to 1-MeV electron irradiation when compared to boron-doped n(+)p silicon solar cells. In addition to improved radiation resistance, considerable damage recovery by annealing is observed in the counterdoped cells at T less than or equal to 100 C. Deep level transient spectroscopy measurements are used to identify the defect whose removal results in the low-temperature aneal. It is suggested that the increased radiation resistance of the counterdoped cells is primarily due to interaction of the lithium with interstitial oxygen.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Applied Physics Letters (ISSN 0003-6951); 44; 1071-107
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  • 50
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    Nature of gamma-prime precipitates in rheocast IN-100 alloy (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The microstructures of commercial VIM-cast and rheocast (Apelian and Cheng, 1983) IN-100 superalloy are investigated optically and by two-stage replica TEM, with an emphasis on the nature of the gamma-prime (GP) precipitates. Photomicrographs at magnifications of 39, 390, 2145, and 6630 are presented and discussed. VIM-cast IN-100 has dendritic structure, 10-20-micron primary GP particles, and uniformly distributed cuboid GP precipitates of a uniform size (about 0.5 micron). Rheocast IN-100 (stirred 20 min at 350 rpm, 1291 C, and 0.0006 torr) has a nondendritic structure, 20-100-micron primary GP particles, and a smaller volume fraction of cuboid GP precipitates with a bimodal (either 1-1.5 microns or less than 0.5 micron) size distribution. Such distribution should increase fatigue-crack-nucleation resistance.
    Keywords: METALLIC MATERIALS
    Type: Journal of Materials Science Letters (ISSN 0261-8028); 3; 71-73
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  • 51
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    Glossary of terms used in solar energy (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Energy (ISSN 0038-092X); 33; 1, 19
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  • 52
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    Friction and wear of some ferrous-base metallic glasses (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminium oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.
    Keywords: METALLIC MATERIALS
    Type: ASLE Transactions; 27; 295-303;
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    Fracture mechanics and surface chemistry investigations of environment-assisted crack growth (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is pointed out that environment-assisted subcritical crack growth in high-strength steels and other high-strength alloys (particularly in hydrogen and in hydrogenous environments) is an important technological problem of long standing. This problem is directly related to issues of structural integrity, durability, and reliability. The terms 'hydrogen embrittlement' and 'stress corrosion cracking' have been employed to describe the considered phenomenon. This paper provides a summary of contributions made during the past ten years toward the understanding of environmentally assisted crack growth. The processes involved in crack growth are examined, and details regarding crack growth and chemical reactions are discussed, taking into account crack growth in steels exposed to water/water vapor, the effect of hydrogen, reactions involving hydrogen sulfide, and aspects of fracture surface morphology and composition. Attention is also given to the modeling of crack growth response, crack growth in gas mixtures, and the interaction of solute atoms with the crack-tip stress field.
    Keywords: METALLIC MATERIALS
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  • 54
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    Effect of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effects of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate at frequencies of 1 Hz and 10 Hz were investigated. Twenty-five mm thick compact specimens were subjected to constant amplitude fatigue testing at a load ratio of 0.2. Fatigue crack growth rates were calculated from effective crack lengths determined using a compliance method. Tests were conducted in hard vacuum and at water vapor partial pressures ranging from 94 Pa to 3.8 kPa. Fatigue crack growth rates were frequency insensitive under all environment conditions tested. For constant stress intensity factor ranges crack growth rate transitions occurred at low and high water vapor pressures. Crack growth rates at intermediate pressures were relatively constant and showed reasonable agreement with published data for two Al-Cu-Mg alloys. The existence of two crack growth rate transitions suggests either a change in rate controlling kinetics or a change in corrosion fatigue mechanism as a function of water vapor pressure. Reduced residual deformation and transverse cracking specimens tested in water vapor versus vacuum may be evidence of embrittlement within the plastic zone due to environmental interaction.
    Keywords: METALLIC MATERIALS
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    Influence of precracked specimen configuration and starting stress intensity on the stress corrosion cracking of 4340 steel (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Since the pioneer work of Brown (1966), precracked specimens and related fracture mechanics analyses have been extensively used to study stress corrosion cracking. Certain questions arose in connection with initial attempts to prepare standardized recommended practices by ASTM Committee G-1 on Corrosion of Metals. These questions were related to adequacy of test control as it pertains to acceptable limits of variability, and to validity of expressions for stress intensity and crack-surface displacements for both specimen configurations. An interlaboratory test program, was, therefore, planned with the objective to examine the validity of KIscc testing for selected specimen configurations, materials,and environmental systems. The results reported in the present paper include details of a single laboratory test program. The program was conducted to determine if the threshold value of stress intensity for onset and arrest of stress corrosion cracking was independent for the two specimen configurations examined.
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    Chemical reactions involved in the initiation of hot corrosion of IN-738 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Sodium-sulfate-induced hot corrosion of preoxidized IN-738 was studied at 975 C with special emphasis placed on the processes occurring during the long induction period. Thermogravimetric tests were run for predetermined periods of time, and then one set of specimens was washed with water. Chemical analysis of the wash solutions yielded information about water soluble metal salts and residual sulfate. A second set of samples was cross sectioned dry and polished in a nonaqueous medium. Element distributions within the oxide scale were obtained from electron microprobe X-ray micrographs. Evolution of SO was monitored throughout the thermogravimetric tests. Kinetic rate studies were performed for several pertinent processes; appropriate rate constants were obtained from the following chemical reactions; Cr203 + 2 Na2S04(1) + 3/2 02 yields 2 Na2Cr04(1) + 2 S03(g)n TiO2 + Na2S04(1) yields Na20(T102)n + 503(g)n T102 + Na2Cro4(1) yields Na2(T102)n + Cr03(g).
    Keywords: METALLIC MATERIALS
    Type: Electrochemical Society, Journal (ISSN 0013-4651); 131; 2985-299
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  • 57
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    High-temperature thermoelectric energy converstion. I - Theory (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The high-temperature thermoelectric energy-conversion theory is examined. It is shown that semiconductors are the logical choices for high-figure of merit-value materials, but the requirements for optimization differ depending on whether the material is classed as a broad-band or narrow-band semiconductor. Optimization is discussed as a function of temperature. Phonon scattering mechanisms are considered; and for the reduction of thermal conductivity, basic material guidelines are given. Although experimental results indicate that ZT (where Z is the figure of merit and T is the temperature) of about 1 represents an upper limit, there is in fact, no theoretical limitation. It is unlikely that the Z values will be significantly reduced by radiation transfer at temperatures lower than 2000 K. The current status of materials research is also considered. The rare-earth chalcogenides which behave as n-type semi-conductors and the boron-rich borides which exhibit hopping p-type conductivity behavior are the materials that show promise for high-temperature Z values. The reasons for low thermal conductivities in these materials is discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Energy Conversion and Management (ISSN 0196-8904); 24; 4, 19; 317-329
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  • 58
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    Influence of precracked specimen configuration and starting stress intensity on the stress corrosion cracking of 4340 steel (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Experimental results are presented from a study of the effects of precracked specimen configuration and initial starting stress intensity on crack growth rate and threshold stress intensity, for both onset of cracking and crack arrest. Attention is given to AISI 4340 steel in a 3.5-percent NaCl solution, for configurations of a single edge-cracked specimen tested in cantilever bending under constant load, and a modified compact specimen bolt loaded to a constant deflection. The threshold stress intensity value determined was independent of specimen configuration, if the stress intensity value associated with the compact specimen is taken where the discontinuous break occurs in the velocity-stress intensity curve.
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  • 59
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    Solar tests of aperture plate materials for solar thermal dish collectors (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: If a malfunction occurs in a solar thermal point-focus distributed receiver power plant while a concentrator is pointed at the sun, motion of the concentrator may stop. As the sun moves relative to the earth, the spot of concentrated sunlight then slowly walks off the receiver aperture, across the receiver face plate, and perhaps across adjacent portions of the concentrator. Intense local heating by the concentrated sunlight may damage or destroy these parts. The behavior of various materials under conditions simulating walk-off of a parabolic dish solar collector were evaluated. Each test consisted of exposure to concentrated sunlight at a peak flux density of about 7000 kW/square meter for 15 minutes. Types of materials tested included graphite, silicon carbide, silica, various silicates, alumina, zirconia, aluminum, copper, steel, and polytetrafluoroethylene. The only material that neither cracked nor melted was grade G-90 graphite. Grade CS graphite, a lower cost commercial grade, cracked half-way across, but did not fall apart. Both of these grades are medium-grain extruded graphites. A graphite cloth (graphitized polyacrylonitrile) showed fair performance when tested as a single thin ply; it might be useful as a multi-ply assembly. High purity slipcast silica showed some promise also.
    Keywords: ENERGY PRODUCTION AND CONVERSION
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  • 60
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    Mechanical-contact-induced transformation from the amorphous to the partially crystalline state in metallic glass (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Friction and wear tests were conducted with 3.2- and 6.4-millimeter-diameter aluminum oxide spheres sliding, in reciprocating motion, on a Fe67Co18B14Si1 metallic foil. Crystallites with a size range of 10 to 150 nanometers were produced on the wear surface of the amorphous alloy. A strong interaction between transition metals and metalloids such as silicon and boron results in strong segregation during repeated sliding, provides preferential transition metal-metalloid clustering in the amorphous alloy, and subsequently produces the diffused honeycomb structure formed by dark grey bands and primary crystals, that is, alpha-Fe in the matrix. Large plastic flow occurs on an amorphous alloy surface with sliding and the flow film of the alloy transfers to the aluminum oxide pin surface. Multiple slip bands due to shear deformation are observed on the side of the wear track. Two distinct types of wear debris were observed as a result of sliding: an alloy wear debris, and/or powdery-whiskery oxide debris.
    Keywords: METALLIC MATERIALS
    Type: Thin Solid Films (ISSN 0040-6090); 118; 363-373
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  • 61
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    Near-optimum design of GaAs-based concentrator space solar cells for 80 C operation (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Using a detailed computer simulation model and reasonable values of optical, geometrical and material parameters from current published literature, parameter optimization studies were performed on two cell geometries, namely, the circular geometry for a Cassegrainian concentrator with 100 AM0, 80 C operation and the rectangular geometry for a venetian blind concentrator with 20 AM0, 80 C operation. For each cell geometry, three cell configurations were considered: p/n AlGaAs/GaAs; n/p AlGaAs/GaAs; and, n/p GaAs shallow homojunction. The studies show the possibility of designing GaAs-based space solar cells with beginning-of-life efficiencies exceeding 22 percent at 20 to 100 AM0, 80 C and probable efficiency degradation of less than 15 percent after a 70 percent reduction in diffusion length in each cell region.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Applied Physics Communications (ISSN 0277-9374); 4; 2-3,; 97-119
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  • 62
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    Solar tests of aperture plate materials for solar thermal dish collectors (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: If a malfunction occurs in a solar thermal point-focus distributed receiver power plant while a concentrator is pointed at the sun, motion of the concentrator may stop. As the sun moves relative to the earth, the spot of concentrated sunlight then slowly walks off the receiver aperture, across the receiver face plate, and perhaps across adjacent portions of the concentrator. Intense local heating by the concentrated sunlight may damage or destroy these parts. The behavior of various materials under conditions simulating walk-off of a parabolic dish solar collector were evaluated. Each test consisted of exposure to concentrated sunlight at a peak flux density of about 7000 kW/square meter for 15 minutes. Types of materials tested included graphite, silicon carbide, silica, various silicates, alumina, zirconia, aluminum, copper, steel, and polytetrafluroethylene. The only material that neither cracked nor melted was grade G-90 graphite. Grade CS graphite, a lower cost commercial grade, cracked half-way across, but did not fail apart. Both of these grades are medium-grain extruded graphites. A graphite cloth (graphitized polyacrylonitrile) showed fair performance when tested as a single thin ply; it might be useful as a multi-ply assembly. High purity slipcast silica showed some promise also.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: ASME, Transactions, Journal of Solar Energy Engineering (ISSN 0199-6231); 106; 408-415
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  • 63
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    Solar-cell interconnect design for terrestrial photovoltaic modules (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Useful solar cell interconnect reliability design and life prediction algorithms are presented, together with experimental data indicating that the classical strain cycle (fatigue) curve for the interconnect material does not account for the statistical scatter that is required in reliability predictions. This shortcoming is presently addressed by fitting a functional form to experimental cumulative interconnect failure rate data, which thereby yields statistical fatigue curves enabling not only the prediction of cumulative interconnect failures during the design life of an array field, but also the quantitative interpretation of data from accelerated thermal cycling tests. Optimal interconnect cost reliability design algorithms are also derived which may allow the minimization of energy cost over the design life of the array field.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: ASME, Transactions, Journal of Solar Energy Engineering (ISSN 0199-6231); 106; 379-386
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  • 64
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    Deformation and fracture behavior of Ni-Mo-Al(gamma/gamma prime-alpha) in situ composite (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Tensile properties of a directionally solidified (DS) eutectic alloy of the nominal composition Ni-33 Mo-5.7 Al (weight percent) have been investigated both at room temperature and elevated temperatures. The microstructure-mechanical property relationship has been studied for the alloy both in the as-DS and heat-treated conditions. Changes in the yield strength, the work hardening behavior, and the fracture morphology have been explained in terms of the microstructural changes due to the heat treatment. The yield drops observed have been attributed to the microdebonding due to the possible segregation of impurities at the fiber-matrix interface, and partly to the strain aging. The deformation mechanism has been identified to be the cutting of gamma prime particles.
    Keywords: METALLIC MATERIALS
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science (ISSN 0360-2133); 15A; 1905-191
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  • 65
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    Deformation and erosion of f.c.c. metals and alloys under cavitation attack (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Experimental investigations have been conducted to determine the early stages of cavitation attack on 6061-T6 aluminum alloy, electrolytic tough pitch copper, brass, and bronze, all having polycrystalline fcc matrices. The surface profiles and scanning electron micrographs show that the pits are initially formed at the grain boundaries, while the grain surfaces are progressively roughened by multiple slip and twinning. The initial erosion is noted to have occurred from the material in the grain boundaries, as well as by fragmentation of part of the grains. Further erosion occurred by shearing and necking of the surface undulations caused by plastic deformation. The mean penetration depth, computed on the basis of mass loss, was lowest on the bronze and greatest on the copper. Attention is given to the relation of cavitation attack to grain size, glide stress and stacking fault energy.
    Keywords: METALLIC MATERIALS
    Type: Materials Science and Engineering (ISSN 0025-5416); 67; 55-67
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  • 66
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    Elevated temperature compressive steady state deformation and failure in the oxide dispersion strengthened alloy MA 6000E (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The compressive flow strength-strain rate behavior of the oxide-dispersion-strengthened alloy MA 6000E has been studied in the temperature range 1144-1366 K, with strain rates ranging from 2.1 x 10 to the -5th to 2.1 x 10 to the -7th per s. It is found that the inherent strength of the alloy is essentially the same in all test directions and that the low strength observed in tensile tests results from the inability of grain boundaries to support high tensile stresses. The failure of MA 6000E under high-temperature, slow plastic flow conditions is shown to be the result of concentrated slip. Slow plastic deformation in MA 6000E can be described by a threshold stress model of creep where threshold stresses are calculated from relatively fast testing procedures and the effective stress exponent for creep is assumed to be 3.5.
    Keywords: METALLIC MATERIALS
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science (ISSN 0360-2133); 15A; 1753-176
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  • 67
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    Oxidation behavior of a thermal barrier coating (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Thermal barrier coatings, consisting of a plasma sprayed calcium silicate ceramic layer and a CoCrAlY or NiCrAlY bond coat, were applied on B-1900 coupons and cycled hourly in air in a rapid-response furnace to maximum temperatures of 1030, 1100, or 1160 C. Eight specimens were tested for each of the six conditions of bond-coat composition and temperature. Specimens were removed from test at the onset of failure, which was taken to be the formation of a fine surface crack visible at 10X magnification. Specimens were weighed periodically, and plots of weight gain vs time indicate that weight is gained at a parabolic rate after an initial period where weight was gained at a much greater rate. The high initial oxidation rate is thought to arise from the initially high surface area in the porous bond coat. Specimen life (time to first crack) was found to be a strong function of temperature. However, while test lives varied greatly with time, the weight gain at the time of specimen failure was quite insensitive to temperature. This indicates that there is a critical weight gain at which the coating fails when subjected to this test.
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  • 68
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    A study of the effect of solid particle impact and particle shape on the erosion morphology of ductile metals (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Impulsive versus steady jet impingement of spherical glass bead particles on metal surfaces was studied using a gas gun facility and a commercial sand blasting apparatus. Crushed glass particles were also used in the sand blasting apparatus as well as glass beads. Comparisons of the different types of erosion patterns were made. Scanning electron microscopy, surface profilometry and energy dispersive X-ray spectroscopy analysis were used to characterize erosion patterns. The nature of the wear can be divided into cutting and deformation, each with its own characteristic features. Surface chemistry analysis indicates the possiblity of complex chemical and/or mechanical interactions between erodants and target materials.
    Keywords: METALLIC MATERIALS
    Type: Journal of Microscopy (ISSN 0022-2720); 135; 49-59
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  • 69
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    The degradation mechanism of Ti-Pd-Ag solar cell contacts by an accelerated electrochemical testing technique (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Cells (ISSN 0379-6787); 11; 189-193
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  • 70
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    Improved Nominal Operating Cell Temperature (NOCT) test procedure (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A procedure is developed to improve testing of Nominal Operating Cell Temperature (NOCT) as it applies to solar energy conversion modules. NOCT is a direct reflection of module thermal design and is closely related to the representative ambient temperature. It is also a key to array energy production and estimates of module lifetimes. Present NOCT test and evaluation procedures are inconsistent, producing significant scatter. Test refinements would specify a clear sky, the addition of 10% to the insolation level for ground reflection, the addition of a ground emission factor of 0.8 (at 30C ground temperature), an effective wind direction of 135 degrees from the North, and a module tilt of 30 degrees from the horizon.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Proc. of the 24th Project Integration Meeting; p 639-642
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  • 71
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    Module Hipot and ground continuity test results (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Hipot (high voltage potential) and module frame continuity tests of solar energy conversion modules intended for deployment into large arrays are discussed. The purpose of the tests is to reveal potentially hazardous voltage conditions in installed modules, and leakage currents that may result in loss of power or cause ground fault system problems, i.e., current leakage potential and leakage voltage distribution. The tests show a combined failure rate of 36% (69% when environmental testing is included). These failure rates are believed easily corrected by greater care in fabrication.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Proc. of the 24th Project Integration Meeting; p 619-631
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  • 72
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    Advanced module development overview (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Crystalline silicon solar power modules are examined for reliability and cost effectiveness. A goal of 12% solar energy conversion efficiency is considered feasible at a cost of 12/kWh, and a decision is made to limit consideration to float zone silicon wafer and dendritic web silicone modules. A preliminary module packaging configuration of glass/ethylene vinyl acetate/plastic film is selected. Anticipated module efficiency levels are 12.6% at 25 C and 11.5% at NOCT (Nominal Operating Cell Temperature).
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 609-611
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  • 73
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    Failure analysis of thin-film amorphous-silicon solar-cell modules (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A failure analysis of thin film amorphous silicon solar cell modules was conducted. The purpose of this analysis is to provide information and data for appropriate corrective action that could result in improvements in product quality and reliability. Existing techniques were expanded in order to evaluate and characterize degradational performance of a-Si solar cells. Microscopic and macroscopic defects and flaws that significantly contribute to performance degradation were investigated.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 657-662
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  • 74
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    Status of high-efficiency module design and fabrication (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The fabrication of high efficiency solar energy conversion modules (13% efficiency at NOCT - Nominal Operating Cell Temperature) is discussed, with emphasis placed on reducing NOCT, since reduced operating temperature improves both efficiency and module lifetime.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 613-618
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  • 75
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    Edge-defined film-fed growth of thin silicon sheets (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Finite element analysis was used on two length scales to understand crystal growth of thin silicon sheets. Thermal-capillary models of entire ribbon growth systems were developed. Microscopic modeling of morphological structure of melt/solid interfaces beyond the point of linear instability was carried out. The application to silicon system is discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 575-586
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  • 76
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    Silicon sheet surface studies (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Several activities were performed in the area of silicon sheet surface studies. An interferometry technique was developed for measuring residual stresses in short, thin silicon sheets. Simulation of abrasion of silicon by diamond and by scrating and indentation tests was carried out. The wear rate in silicon was correlated with a wear model.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 561-570
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  • 77
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    Silicon ribbon stress-strain activities (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The finite element method is used to investigate stress/strain in silicon ribbon. Failure considerations such as residual stress, buckling material non-linearity and creep are discussed. Temperature profiles are presented.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Proc. of the 24th Project Integration Meeting; p 491-515
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  • 78
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    Encapsulation Processing and Manufacturing Yield Analysis (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The development of encapsulation processing and a manufacturing productivity analysis for photovoltaic cells are discussed. The goals were: (1) to understand the relationships between both formulation variables and process variables; (2) to define conditions required for optimum performance; (3) to predict manufacturing yield; and (4) to provide documentation to industry.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 461-469
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  • 79
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    A non-noble front metallization process (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The optimization, evaluation, and demonstration of a solar cell metallization system is discussed. Screen printing, air firing, reducted atmospheres, and conductive air coating were studied.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 421-431
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  • 80
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    Simultaneous junction formation (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: High-risk, high-payoff improvements to a baseline process sequence of simultaneous junction formation of silicon solar cells are discussed. The feasibility of simultaneously forming front and back junctions of solar cells using liquid dopants on dendritic web silicon was studied. Simultaneous diffusion was compared to sequential diffusion. A belt furnace for the diffusion process was tested.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 369-377
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  • 81
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    Georgetown University Photovoltaic Higher Education National Exemplar Facility (PHENEF) (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Several photographs of this facility using photovoltaic (PV) cells are shown. An outline is given of the systems requirements, system design and wiring topology, a simplified block design, module electrical characteristics, PV module and PV module matching.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 87-98
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  • 82
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    High-efficiency crystalline silicon technology development (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The rationale for pursuing high efficiency crystalline silicon technology research is discussed. Photovoltaic energy systems are reviewed as to their cost effectiveness and their competitiveness with other energy systems. The parameters of energy system life are listed and briefly reviewed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 49-56
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  • 83
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    High-efficiency silicon solar cell research (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Progress reports on research in high-efficiency silicon solar cells were presented by eight contractors and JPL. The presentations covered the issues of Bulk and Surface Loss, Modeling, Measurements, and Proof of Concept.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Proc. of the 24th Project Integration Meeting; p 281-282
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  • 84
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    Encapsulation materials research (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Encapsulation materials for solar cells were investigated. The different phases consisted of: (1) identification and development of low cost module encapsulation materials; (2) materials reliability examination; and (3) process sensitivity and process development. It is found that outdoor photothermal aging devices (OPT) are the best accelerated aging methods, simulate worst case field conditions, evaluate formulation and module performance and have a possibility for life assessment. Outdoor metallic copper exposure should be avoided, self priming formulations have good storage stability, stabilizers enhance performance, and soil resistance treatment is still effective.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 145-164
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  • 85
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    Predicting photothermal field performance (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Photothermal field performance in flat plate solar collectors was predicted. An analytical model which incorporates the measured dependency between transmittance loss and UV and temperature exposure levels was developed. The model uses SOLMET weather data extrapolated to 30 years for various sites and module mounting configurations. It is concluded that the temperature is the key to photothermally induced transmittance loss. The sensitivity of transmittance loss to UV level is nonlinear with minimum in curve near one sun. The ethylene vinyl acetate (EVA) results are consistent with 30 year life allocation.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Proc. of the 24th Project Integration Meeting; p 121-128
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  • 86
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    The future of crystalline silicon technology in the US Department of Energy program (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two basic findings were presented in the outlined report. The first is that silicon has a very high potential efficiency, demonstrated improvement in reliability and a significant potential for cost reductions. The second is that the photovoltaic technology development process is highly uncertain, but crystalline silicon technology has a substantial knowledge base to draw from, improving its chances of success. Several issues to be addressed are outlined.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 83-86
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  • 87
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    Summary of the high-efficiency crystalline solar cell research forum (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An outline is given listing the speeches given in each session and the pertinent points is some speeches. There were six session, besides the overview session they were: (1) high efficiency concepts; (2) surface/interface effects; (3) bulk effects; (4) modeling; and (5) high efficiency device processing. Besides the emphasis placed on increasing efficiency of energy conversion, a great amount of discussion was spent on ways to reduce recombination and reducing surface defects.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: JPL Proc. of the 24th Project Integration Meeting; p 57-74
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  • 88
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    Torque command steering law for double-gimbaled control moment gyros applied to rotor energy storage (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A steering law is presented which has all the features required for space applications, assuming the CMG outer gimbal freedom is unlimited. The reason is the idea of mounting all the outer gimbal axes of the CMGs parallel to each other. This allows the decomposition of the steering law problem into a linear one for the inner gimbal angle rates and a planar one for the outer gimbal angle rates. The inner gimbal angle rates are calculated first, since they are not affected by the outer gimbal angle rates. For the calculation of the outer rates, the inner rates are then known quantities. An outer gimbal angle distribution function (to avoid singularities internal to the total angular momentum envelope) generates distribution rates next, and finally the pseudoinverse method is used to insure that the desired total torque is delivered.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 407-422
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  • 89
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    High-efficiency power conversion options for flywheel energy storage systems (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The impact of efficiency on the power system and how efficiency is affected by component types is discussed. Some ac and dc bus configurations are described along with prototype systems.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 349-367
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  • 90
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    Advanced high-power transfer through rotary interfaces (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A roll-ring design that is uniquely suited for rotary signal/power transfer in space applications is described. Two high-power configurations of the roll ring were developed. Present lab-proven hardware is available with power transfer capability of 2 kW at 200 amps and higher power units with 100-kW capability are in the design stage. Theoretical analysis indicated that power levels of kW are possible.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 341-348
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  • 91
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    Reaction wheels for kinetic energy storage (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: In contrast to all existing reaction wheel implementations, an order of magnitude increase in speed can be obtained efficiently if power to the actuators can be recovered. This allows a combined attitude control-energy storage system to be developed with structure mounted reaction wheels. The feasibility of combining reaction wheels with energy storage wwheels is demonstrated. The power required for control torques is a function of wheel speed but this energy is not dissipated; it is stored in the wheel. The I(2)R loss resulting from a given torque is shown to be constant, independent of the design speed of the motor. What remains, in order to efficiently use high speed wheels (essential for energy storage) for control purposes, is to reduce rotational losses to acceptable levels. Progress was made in permanent magnet motor design for high speed operation. Variable field motors offer more control flexibility and efficiency over a broader speed range.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 329-340
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  • 92
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    The multipurpose composite flywheel (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The twin disk composite flywheel shows that the techniques that were developed at Rocketdyne to successfully design, fabricate, and test high-speed rotating machinery (turbopumps) for rocket engines could be used to develop advanced flywheels. This flywheel not only demonstrates that successful mating of metal flywheel characteristics (high torque and ruggedness) and composite flywheel characteristics (lightweight and high energy density) can be achieved, but the unique design lends itself to easy adaptation to other configurations.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 233-242
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  • 93
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    Magnetically suspended reaction wheel assembly (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The magnetically suspended reaction wheel assembly (MSRWA) is the product of a development effort funded by the Air Force Materials Laboratory (AFML) at Wright Patterson AFB. The specific objective of the project was to establish the manufacturing processes for samarium cobalt magnets and demonstrate their use in a space application. The development was successful on both counts. The application portion of the program, which involves the magnetically suspended reaction wheel assembly, is emphasized. The requirements for the reaction wheel were based on the bias wheel requirements of the DSP satellite. The tasks included the design, fabrication, and test of the unit to the DSP program qualification requirements.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 265-279
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  • 94
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    Summary results of the DOE flywheel development effort (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The technology and applications evaluation task focuses on defining performance and cost requirements for flywheels in the various areas of application. To date the DOE program has focused on automotive applications. The composite materials effort entails the testing of new commercial composites to determine their engineering properties. The rotor and containment development work uses data from these program elements to design and fabricate flywheels. The flywheels are then tested at the Oak Ridge Flywheel Evaluation Laboratory and their performance is evaluated to indicate possible areas for improvement. Once a rotor has been fully developed it is transferred to the private sector.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 181-191
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  • 95
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    Westinghouse programs in pulsed homopolar power supplies (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: This document details Westinghouse's ongoing study of homopolar machines since 1929 with the major effort occurring in the early 1970's to the present. The effort has enabled Westinghouse to develop expertise in the technology required for the design, fabrication and testing of such machines. This includes electrical design, electromagnetic analysis, current collection, mechanical design, advanced cooling, stress analysis, transient rotor performance, bearing analysis and seal technology. Westinghouse is using this capability to explore the use of homopolar machines as pulsed power supplies for future systems in both military and commercial applications.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 141-156
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  • 96
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    Comparative energy storage assessment item (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: This analysis, a Space Station application study, rediscovered Integrated Power and Attitude Control (IPAC) and found the approach to have lower initial and resupply weight and lower initial and resupply cost than either battery/CMG or regenerative fuel cell/CMG systems. Preliminary trade studies were performed comparing (IPAC) with equivalent independent electrochemical power and control moment gyro (CMG) control approaches. Technologies considered to have adequate status for an initial Space Station were: (1) nickel cadmium batteries (NiCd batteries), (2) regenerative fuel cells (RFC), (3) Skylab class CMG's, and (4) state of the art IPAC using metal wheels and ball bearing suspension (SOA-IPAC). An advanced IPAC (ADV-IPAC) employing composite rotor material and magnetic suspension was included in the comparisons to illustrate a possible range of performance and cost of inertial systems. The candidates were compared on the basis of initial weight and cost and on the basis of resupply weight and cost for a 15 year mission. Thus, SOA-IPAC would appear to be an attractive approach for the initial Space Station and possible technology improvements would further the appeal for the initial and/or growth Space Station.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 91-99
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  • 97
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    European development experience on energy storage wheels for space (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: High speed fiber composite rotors suspended by contactless magnetic bearings were produced. European industry has acquired expertise in the study and fabrication of energy storage wheels and magnetic suspension systems for space. Sufficient energy density performance for space viability is being achieved on fully representative hardware. Stress cycle testing to demonstrate life capability and the development of burst containment structures remains to be done and is the next logical step.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 65-73
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  • 98
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    Dynamics and controls working group summary (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The technology status of the dynamics and controls discipline as it applies to energy storage wheel systems was evaluated. No problems were identified for which an adequate solution could not be proposed. Design issues that influence control were addressed. The dynamics and control aspects associated with the energy storage system concept and its various constituent parts, and the control tasks attendant to large, manned spacecraft are discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 39-48
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  • 99
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    A summary of the 1983 Integrated Flywheel Technology Workshop (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The use of flywheels to perform the functions of attitude control and/or energy storage on a variety of space missions was studied. Integrated Flywheel Technology was discussed. The four primary objectives are: (1) determine the potential of flywheels for energy storage system applications and for combined energy storage and attitude control concepts; (2) assess the state of the art (SOA) in integrated flywheel technology through a review of government sponsored programs; (3) identify those technology areas which are in critical need of development to meet projected space mission requirements; (4) scope a program for the coordinated development of the required technology.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: An Assessment of Integrated Flywheel System Technol.; p 49-64
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  • 100
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    Electrical/electronics working group summary (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The electrical/electronics, technology area was considered. It was found that there are no foreseeable circuit or component problems to hinder the implementation of the flywheel energy storage concept. The definition of the major component or technology developments required to permit a technology ready date of 1987 was addressed. Recommendations: motor/generators, suspension electronics, power transfer, power conditioning and distribution, and modeling. An introduction to the area of system engineering is also included.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Langley Research Center An Assessment of Integrated Flywheel System Technol.; p 29-38
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