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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

An evaluation of Ada for Al applications

Expert system technology seems to be the most promising type of Artificial Intelligence (AI) application for Ada. An expert system implemented with an expert system shell provides a highly structured approach that fits well with the structured approach found in Ada systems. The current commercial expert system shells use Lisp. In this highly structured situation a shell could be built that used Ada just as well. On the other hand, if it is necessary to deal with some AI problems that are not suited to expert systems, the use of Ada becomes more problematical. Ada was not designed as an AI development language, and is not suited to that. It is possible that an application developed in say, Common Lisp could be translated to Ada for actual use in a particular application, but this could be difficult. Some standard Ada packages could be developed to make such a translation easier. If the most general AI programs need to be dealt with, a Common Lisp system integrated with the Ada Environment is probably necessary. Aside from problems with language features, Ada, by itself, is not well suited to the prototyping and incremental development that is well supported by Lisp.

Wallace, David R.↗
NASA NTRS1988

Modeling magnetospheric plasma; Proceedings of the First Huntsville Workshop on Magnetosphere/Ionosphere Plasma Models, Guntersville, AL, Oct. 14-16, 1987

The conference presents papers on the global modeling of magnetospheric plasma processes, the modeling of the midlatitude ionosphere and plasmasphere, the modeling of the auroral zone and boundary layer, the modeling of the polar magnetosphere and ionosphere, and the modeling of the plasma sheet and ring current. Particular attention is given to the kinetic approach in magnetospheric plasma transport modeling, self-consistent neutral point current and fields from single particle dynamics, preliminary statistical survey of plasmaspheric ion properties from observations by DE 1/RIMS, and a model of auroral potential structures based on dynamics explorer plasma data. Other topics include internal shear layers in auroral dynamics, quantitative parameterization of energetic ionospheric ion outflow, and open flux merging in an expanding polarcap model.

Moore, T. E.↗
NASA NTRS1989

The common engine concept for ALS application - A cost reduction approach

Future launch systems require the application of propulsion systems which have been designed and developed to meet mission model needs while providing high degrees of reliability and cost effectiveness. Vehicle configurations which utilize different propellant combinations for booster and core stages can benefit from a common engine approach where a single engine design can be configured to operate on either set of propellants and thus serve as either a booster or core engine. Engine design concepts and mission application for a vehicle employing a common engine are discussed. Engine program cost estimates were made and cost savings, over the design and development of two unique engines, estimated.

Bair, E. K.↗
NASA NTRS1989

The photovoltaic properties of an Al In As/InP heterojunctions grown by LPE method

Work is presented on heterojunction solar cells which were studied under the NASA/Arizona State University intern program. The heterojunction solar cells were fabricated by the liquid phase epitaxy method. The basic conversion efficiency was measured at 5 percent. It was determined that a thicker epilayer is needed, and that the density of recombination center should be reduced to give a smaller saturation current and hence a larger open-circuit voltage.

Wang, Edward Y.↗
NASA NTRS1989

Microstructure and tensile properties of Fe-40 at. pct Al alloys with C, Zr, Hf, and B additions

The influence of small additions of C, Zr, and Hf, alone or in combination with B, on the microstructure and tensile behavior of substoichiometric FeAl was investigated. Tensile properties were determined from 300 to 1100 K on powder which was consolidated by hot extrusion. All materials possessed some ductility at room temperature, although ternary additions generally reduced ductility compared to the binary alloy. Adding B to the C- and Zr-containing alloys changed the fracture mode from intergranular to transgranular and restored the ductility to approximately 5 percent elongation. Additions of Zr and Hf increased strength up to about 900 K. Fe6Al6Zr and Fe6Al6Hf precipitates, both with identical body-centered tetragonal structures, were identified as the principal second phase in these alloys. Strength decreased steadily as temperature increased above 700 K, as diffusion-assisted mechanisms became operative. Although all alloys had similar strengths at 1100 K, Hf additions significantly improved high-temperature ductility by suppressing cavitation.

Gaydosh, D. J.↗
NASA NTRS1991

Superplastic forming of Al-Li alloys for lightweight, low-cost structures

Superplastic forming of advanced aluminum alloys is being evaluated as an approach for fabricating low-cost, light-weight, cryogenic propellant tanks. Built-up structure concepts (with inherent reduced scrap rate) are under investigation to offset the additional raw material expenses incurred by using aluminum lithium alloys. This approach to fabrication offers the potential for significant improvements in both structural efficiency and overall manufacturing costs. Superplasticity is the ability of specially processed material to sustain very large forming strains without failure at elevated temperatures under controlled deformation conditions. It was demonstrated that superplastic forming technology can be used to fabricate complex structural components in a single operation and increase structural efficiency by as much as 60 percent compared to conventional configurations in skin-stiffened structures. Details involved in the application of this technology to commercial grade superplastic aluminum lithium material are presented. Included are identification of optimum forming parameters, development of forming procedures, and assessment of final part quality in terms of cavitation volume and thickness variation.

Hales, Stephen J.↗
NASA NTRS1991

Natural aging and reversion behavior of Al-Cu-Li-Ag-Mg alloy Weldalite (tm) 049

This study was initiated to understand the natural aging and reversion behavior of Weldalite (trademark) 049 in tempers without cold work. Of particular interest are: (1) the microstructural basis for the high strength in the T4 condition; (2) an explanation of the reversion phenomenon; and (3) the effect of re-aging at room temperature after a reversion treatment. Mechanical properties were measured and transmission electron microscopy (TEM) analysis performed at various stages of microstructural development during aging, reversion, and subsequent re-aging.

Gayle, Frank W.↗
NASA NTRS1991

Systems integration and demonstration of advanced reusable structure for ALS

The objective was to investigate the potential of advanced material to achieve life cycle cost (LCC) benefits for reusable structure on the advanced launch system. Three structural elements were investigated - all components of an Advanced Launch System reusable propulsion/avionics module. Leading aeroshell configurations included sandwich structure using titanium, graphite/polyimide (Gr/PI), or high-temperature aluminum (HTA) face sheets. Thrust structure truss concepts used titanium, graphite/epoxy, or silicon carbide/aluminum struts. Leading aft bulkhead concepts employed graphite epoxy and aluminum. The technical effort focused on the aeroshell because the greatest benefits were expected there. Thermal analyses show the structural temperature profiles during operation. Finite element analyses show stresses during splash-down. Weight statements and manufacturing cost estimates were prepared for calculation of LCC for each design. The Gr/PI aeroshell showed the lowest potential LCC, but the HTA aeroshell was judged to be lower risk. A technology development plan was prepared to validate the applicable structural technology.

Gibbins, Martin N.↗
NASA NTRS1990

Liquid hydrogen turbopump ALS advanced development program. Volume 1: Hot fire unit

The interface criteria for the Turbopump Test article (TPA) and the Component Test Facility located at NASA, Stennis Space Center is defined by this interface Control Document (ICD). TPA ICD Volume 2 is submitted for the Cold Gas Drive Turbopump Test Article, which is generally similar but incorporates certain changes, particularly in fluid requirements and in instrumentation needs. For the purposes of this ICD, the test article consists of the Hot Fire Drive Turbopump mounted on its test cart, readied for installation in the component test facility. It should be emphasized that the LH2 turbopump program is still in its early concept design phase. Design of the turbopump, test cart, and spools are subject to revisions until successful conclusion of the Detail Design Review (DDR).

Lindley, Bruce↗
NASA NTRS1991

The case for teaming on the ALS-STME program

The analysis concludes that the nation needs to proceed with a new LOX/LH2 rocket engine program now. It is also concluded that open competition now will have deleterious impacts on the competitive viability of the liquid rocket engine industry. Teaming, however, provides a way to solve todays concerns while enhancing the option for open competition in the future.

Morea, S. F.↗
NASA NTRS1991

The effect of TiB2 reinforcement on the mechanical properties of an Al-Cu-Li alloy-based metal-matrix composite

The addition of ceramic particles to aluminum based alloys can substantially improve mechanical properties, especially Young's modulus and room and elevated temperature strengths. However, these improvements typically occur at the expense of tensile ductility. The mechanical properties are evaluated to a metal matrix composite (MMC) consisting of an ultrahigh strength aluminum lithium alloy, Weldalite (tm) 049, reinforced with TiB2 particles produced by an in situ precipitation technique called the XD (tm) process. The results are compared to the behavior of a nonreinforced Weldalite 049 variant. It is shown that both 049 and 049-TiB2 show very attractive warm temperature properties e.g., 625 MPa yield strength at 150 C after 100 h at temperature. Weldalite 049 reinforced with a nominal 4 v pct. TiB2 shows an approx. 8 pct. increase in modulus and a good combination of strength (529 MPa UTS) and ductility (6.5 pct.) in the T3 temper. And the high ductility of Weldalite 049 in the naturally aged and underaged tempers makes the alloy a good, high strength matrix for ceramic reinforcement.

Source record↗
NASA NTRS1989

ALS rocket engine combustion devices design and demonstration

Work performed during Phase one is summarized and the significant technical and programmatic accomplishments occurring during this period are documented. Besides a summary of the results, methodologies, trade studies, design, fabrication, and hardware conditions; the following are included: the evolving Maintainability Plan, Reliability Program Plan, Failure Summary and Analysis Report, and the Failure Mode and Effect Analysis.

Arreguin, Steve↗