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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Relationships and tectonics of the Jg-7 quadrangle of Ganymede

Craters within the Ganymede Jg-7 quadrangle were divided into seven mappable units. The units represent: (1) irregular or elongate craters, (2) craters with dark ejecta, (3) palimpsests, (4) secondary craters, (5) and craters of young, mature, and old age. Symbols used for crater floors include: (1) flat floors, (2) floors with pits, (3) floora with a central dome or peak, (4) and floors with a central dome and pit. Grooved terrains were divided into five mappable units. Three units of light grooved material represent small, medium, and large grooves, which are arbitrarily divided. The other two units of grooved terrain represent dark grooved materials, and reticulate grooves. Two units of ungrooved dark terrain and two units of ungrooved light terrain were defined. In Galileo Regio, two units were defined repesenting large furrowed grooves, and smaller grooves which are orthogonal to the furrowed grooves.

Glotfelty, M. F.↗
NASA NTRS1984

Modeling glacial climates

Mathematical climate modelling has matured as a discipline to the point that it is useful in paleoclimatology. As an example a new two dimensional energy balance model is described and applied to several problems of current interest. The model includes the seasonal cycle and the detailed land-sea geographical distribution. By examining the changes in the seasonal cycle when external perturbations are forced upon the climate system it is possible to construct hypotheses about the origin of midlatitude ice sheets and polar ice caps. In particular the model predicts a rather sudden potential for glaciation over large areas when the Earth's orbital elements are only slightly altered. Similarly, the drift of continents or the change of atmospheric carbon dioxide over geological time induces radical changes in continental ice cover. With the advance of computer technology and improved understanding of the individual components of the climate system, these ideas will be tested in far more realistic models in the near future.

North, G. R.↗
NASA NTRS1984

Determination of the key parameters affecting historic communications satellite trends

Data representing 13 series of commercial communications satellites procured between 1968 and 1982 were analyzed to determine the factors that have contributed to the general reduction over time of the per circuit cost of communications satellites. The model by which the data were analyzed was derived from a general telecommunications application and modified to be more directly applicable for communications satellites. In this model satellite mass, bandwidth-years, and technological change were the variable parameters. A linear, least squares, multiple regression routine was used to obtain the measure of significance of the model. Correlation was measured by coefficient of determination (R super 2) and t-statistic. The results showed that no correlation could be established with satellite mass. Bandwidth-year however, did show a significant correlation. Technological change in the bandwidth-year case was a significant factor in the model. This analysis and the conclusions derived are based on mature technologies, i.e., satellite designs that are evolutions of earlier designs rather than the first of a new generation. The findings, therefore, are appropriate to future satellites only if they are a continuation of design evolution.

Namkoong, D.↗
NASA NTRS1984

P/M superalloys: A troubled adolescent?

The history of powder metallurgy P/M superalloy technology is reviewed with a comment on the state of the art, and speculates on the technology's future potential growth and maturity.

Dreshfield, R. L.↗
NASA NTRS1984

Scientific and technical training in the Soviet Union

The Soviet Union recognizes that the foundation of their system depends upon complete dedication of the people to the state through thorough psychological training as well as through military training, and through specialized education in the broad fields of engineering, natural sciences, life sciences, social sciences, and education. An outline of the U.S.S.R. educational system indicates the extent of academic training, coupled with on-the-job and military training, that can produce a highly skilled, dedicated, and matured person. Observations on the coupling of political, economic, and psychological training along with the technical training are made, along with some mention of positive and negative aspects of the training.

Spearman, M. L.↗
NASA NTRS1984

NASA space biology accomplishments, 1983-84

Approximately 42 project summaries from NASA's Space Biology Program are presented. Emphasis is placed on gravitational effects on plant and animal life. The identification of gravity perception; the effects of weightlessness on genetic integrity, cellular differentiation, reproduction, development, growth, maturation, and senescence; and how gravity affects and controls physiology, morphology, and behavior of organisms are studied.

Halstead, T. W.↗
NASA NTRS1984

Polycrystalline silicon study: Low-cost silicon refining technology prospects and semiconductor-grade polycrystalline silicon availability through 1988

Photovoltaic arrays that convert solar energy into electrical energy can become a cost effective bulk energy generation alternative, provided that an adequate supply of low cost materials is available. One of the key requirements for economic photovoltaic cells is reasonably priced silicon. At present, the photovoltaic industry is dependent upon polycrystalline silicon refined by the Siemens process primarily for integrated circuits, power devices, and discrete semiconductor devices. This dependency is expected to continue until the DOE sponsored low cost silicon refining technology developments have matured to the point where they are in commercial use. The photovoltaic industry can then develop its own source of supply. Silicon material availability and market pricing projections through 1988 are updated based on data collected early in 1984. The silicon refining industry plans to meet the increasing demands of the semiconductor device and photovoltaic product industries are overviewed. In addition, the DOE sponsored technology research for producing low cost polycrystalline silicon, probabilistic cost analysis for the two most promising production processes for achieving the DOE cost goals, and the impacts of the DOE photovoltaics program silicon refining research upon the commercial polycrystalline silicon refining industry are addressed.

Costogue, E. N.↗
NASA NTRS1984

The application of satellite data to study the effects of latent heat release on cyclones

Generalized energetics were studied for nonlinear inviscid symmetric instability (SI). It was found that the linear theory fails to predict the stability in certain cases where the basic state is transitional between stability and instability. The initial growth of the SI perturbations can be fairly well approximated by linear theory, but the long time nonlinear evaluations will be bonded energetically if the SI region is finite. However, a further extension of the energetics to conditional symmetric instability (CSI) shows that the nonlinear evolution of circulation will energetically depend much more on the precipitation in a complicated way. By treating the latent heat as a source which is implicitly related to the motion field, the existence, uniqueness and stability of steady viscous (CSI) circulations are studied. Viscous CSI circulations are proved to be unique and asymptotically stable when the heat sources are weak and less sensitive to the motion perturbations. By considering the fact that moist updrafts are narrow and using eddy viscosity of 0(1,000 m squared/s) the stability criterion suggests that some frontal rainbands were probably dominated by the CSI mechanism even in their mature quasi-steady stage.

Clark, J. H. E.↗
NASA NTRS1984

Utilization of satellite cloud information to diagnose the energy state and transformations in extratropical cyclones

A study of the contribution of latent heat release to the synoptic scale vertical motions in the Jan. 9-11, 1975 extratropical cyclone case study was completed. Results indicate that early cyclone development was dominated by dry dynamical forcing. However, as the cyclone matured, the influence of latent heating became more significant. This influence appeared to be of two types, (1) the direct impact of heating causing a lowering of surface pressures, and (2) an indirect role in which the heating altered thermal and vorticity gradients and lead to subsequent increases in dry dynamical forcing. The kinetic energy budget was completed and extended to include an available potential energy budget. Focusing on the eddy component of the budgets, results indicate that kinetic energy increased throughout the cyclone's development, with the increase being most pronounced after the onset of significant latent heat release. Latent heating played a strong role not only in generating available potential energy, but also in forcing baroclinic release of potential energy.

Smith, P. J.↗
NASA NTRS1984

Severe storm initiation and development from satellite infrared imagery and Rawinsonde data

The geographical distribution of potential temperatures, mixing ratio, and streamlines of flow patterns at 850, 700, and 500 mb heights are used to understand the prestorm convection and the horizontal convergence of moisture. From the analysis of 21 tornadoes the following conclusions are reached: (1) Strong horizontal convergence of moisture appeared at the 850, 700, and 500 mb levels in the area 12 hours before the storm formation; (2) An abundantly moist atmosphere below 3 km (700 mb) becomes convectively unstable during the time period between 12 and 24 hours before the initiation of the severe storms; (3) Strong winds veering with height with direction parallel to the movement of a dryline, surface fronts, etc; (4) During a 36-hour period, a tropopause height in the areas of interest is lowest at the time of tornadic cloud formation; (5) A train of gravity waves is detected before and during the cloud formation period. Rapid-scan infrared imagery provides near real-time information on the life cycle of the storm which can be summarized as follows: (1) Enhanced convection produced an overshooting cloud top penetrating above the tropopause, making the mass density of the overshooting cloud much greater than the mass density of the surrounding air; (2) The overshooting cloud top collapsed at the end of the mature stage of the cloud development; (3) The tornado touchdown followed the collapse of the overshooting cloud top.

Hung, R. J.↗
NASA NTRS1983

Structure of transient oxides formed on NiCrAl alloys

It is one of the three objectives of the present study to document the fine internal structure of the transient scales in order to clarify the development of the stable alpha-Al2O3 from a structural point of view. Another objective is concerned with the origin of features found in the mature alpha-Al2O3 scales, such as voids, taking into account an examination in the early stages of oxidation. The third objective is to relate any difference in scale structure caused by oxide adherence additives (Y or Zr) to the current oxide adherence theories. The primary effect of short-time oxidation on the NiCrAl substrate structure is found to be production of dislocations and aluminum-depleted phases. The random alpha-Al2O3 scale is the primary oxide phase observed in contact with the metal.

Smialek, J. L.↗
NASA NTRS1984

Elements of computational engine-airframe integration

Computerized flow simulation methods are being developed to refine the traditional engine-airframe integration process. These analyses reduce design risk, minimize wind tunnel and flight test requirements, and provide detailed design information not available by any other means. This paper describes computational tools which have matured sufficiently to permit project applications. Several applications are combined with research studies to illustrate the prediction of high-speed nonlinear phenomena associated with engine inlet flow rate, nacelle shape and position, afterbody shape and integration, propeller slipstream interactions, airframe-induced inlet flow, and pylon integration. Both fighter and transport configurations are used to highlight current capabilities and future requirements.

Boppe, C. W.↗
NASA NTRS1983

A long-lived mesoscale convective complex. I - The mountain-generated component

The South Park Area Cumulus Experiment (SPACE) was conducted during the summer of 1977, and takes into account meteorological developments in a broad, elevated basin called South Park, which is located northeast of Colorado Springs, Colorado. The experiment was designed to investigate the organization of the mesoscale and storm-scale systems in detail over South Park. Many of the convective storms which were observed in the developing stages over South Park participated in the genesis of mesoscale convective complexes (MCCs) on the meso-alpha-scale. The present investigation is concerned with the evolution of the second MCC of this episode, which matured on the evening of August 4, 1977. Attention is given to the events from the preconvective stage early on August 4 to the incipient MCC stage in the early evening.

Cotton, W. R.↗
NASA NTRS1983

Neutral and ion chemistry and solar fluxes

Advances that have been made in neutral and ion chemistry in the thermosphere and in solar flux measurements since the 1979 meeting of the IAGA are surveyed. Attention is given to the issues that have arisen in areas previously considered resolved. It is believed that the field has reached a state of maturity in which many of the remaining issues are subtle and present fairly complex problems. Of considerable importance at the present time is the need for good measurements of the O(+) (2D) species, owing to its pivotal role in the overall thermospheric chemistry. Also required are careful and comprehensive studies of the vibrationally excited species. An important concern in the field is the absence of an orbiting extreme and far-ultraviolet solar flux monitor. It is pointed out that measurements in the foreseeable future will be restricted to short duration observations by a variety of instruments.

Torr, M. R.↗
NASA NTRS1983

Environmental Control and Life Support for an evolutionary Space Station

The requirements for the Space Station are being defined. The Environmental Control/Life Support System (ECLSS) is one of its 13 systems. The ECLSS is further divided into five functional categories. Major ones are the Air Revitalization and Water Reclamation Systems. The paper presents ECLSS performance requirements, average design loads and fluids interfaces. The major cost savings of regenerable ECLSS techniques versus the open loop approach are quantified. Issues impacting ECLSS design are cited. Priority regenerable ECLSS developments are reviewed including the Electrochemical CO2 Concentrator, Static Feed Electrolyzer and Automated Control/Monitor Instrumentation. Baseline and alternative approaches are cited. The ECLSS planning issues are reviewed including functional boundaries, planning schedule, technology maturity definition and technology gaps. The paper concludes with a review of water electrolysis as a Space Station utility impacting ECLSS design.

Quattrone, P. D.↗
NASA NTRS1983

Silicon material technology status

Silicon has been the basic element for the electronic and photovoltaic industries. The use of silicon as the primary element for terrestrial photovoltaic solar arrays is projected to continue. The reasons for this projection are related to the maturity of silicon technology, the ready availability of extremely pure silicon, the performance of silicon solar cells, and the considerable present investment in technology and manufacturing facilities. The technologies for producing semiconductor grade silicon and, to a lesser extent, refined metallurgical grade silicon are considered. It is pointed out that nearly all of the semiconductor grade silicon is produced by processes based on the Siemens deposition reactor, a technology developed 26 years ago. The state-of-the-art for producing silicon by this process is discussed. It is expected that efforts to reduce polysilicon process costs will continue.

Lutwack, R.↗
NASA NTRS1984

Operational awareness in future space transportation system concepts and technology selections

An analysis of operations for a two-stage, fully reusable future space transportation system has been performed, and the results are discussed. The value of conducting an analysis of operations in the conceptual design phase to produce a highly productive system was demonstrated by obtaining estimated reductions in resources and ground turnaround time and comparing them with estimated mature Shuttle program requirements. Cooperative efforts by users, future vehicle designers, and operations analysts during the conceptual design phase are shown to produce an efficient vehicle design with broad market potential. The synergistic effects of vehicle design configuration, subsystems, and procedures can enhance productivity of the transportation system as measured by flexibility, availability, and viability. Advanced technologies and subsystems beneficial to such a system are identified.

Eide, D. G.↗
NASA NTRS1983

Packet telemetry and packet telecommand - The new generation of spacecraft data handling techniques

Because of rising costs and reduced reliability of spacecraft and ground network hardware and software customization, standardization Packet Telemetry and Packet Telecommand concepts are emerging as viable alternatives. Autonomous packets of data, within each concept, which are created within ground and space application processes through the use of formatting techniques, are switched end-to-end through the space data network to their destination application processes through the use of standard transfer protocols. This process may result in facilitating a high degree of automation and interoperability because of completely mission-independent-designed intermediate data networks. The adoption of an international guideline for future space telemetry formatting of the Packet Telemetry concept, and the advancement of the NASA-ESA Working Group's Packet Telecommand concept to a level of maturity parallel to the of Packet Telemetry are the goals of the Consultative Committee for Space Data Systems. Both the Packet Telemetry and Packet Telecommand concepts are reviewed.

Hooke, A. J.↗