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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Study of LANDSAT-D thematic mapper performance as applied to hydrocarbon exploration

Improved delineation of known oil and gas fields in southern Ontario and a spectacularly high amount of structural information on the Owl Creek, Wyoming scene were obtained from analysis of TM data. The use of hue, saturation, and value image processing techniques on a Death Valley, California scene permitted direct comparison of TM processed imagery with existing 1:250,000 scale geological maps of the area and revealed small outcrops of Tertiary volcanic material overlying Paleozoic sections. Analysis of TM data over Lawton, Oklahoma suggests that the reducing chemical environment associated with hydrocarbon seepage change ferric iron to soluble ferrous iron, allowing it to be leached. Results of the band selection algorithm show a suprising consistency, with the 1,4,5 combination selected as optimal in most cases.

Everett, J. R.↗
NASA NTRS1984

Global habitability and earth remote sensing

Since 1960, when NASA launched the Tiros satellite to study the atmosphere of the earth, great advances have been made in the study of the earth system by means of remote sensing. It is felt that the time has come for assembling the separate pieces into a coherent whole. Work has, therefore, been conducted to develop a concept called 'global habitability'. The objective of the considered program is to investigate long-term physical, chemical, and biological trends and changes in the earth's environment, including its atmosphere, land masses, and oceans. The program is specifically concerned with a study of the effects of natural and human activities on the earth's environment, and with the future effects on biological productivity and habitability of the earth by man and by other species.

Tilford, S. G.↗
NASA NTRS1985

Nebular volatile fractionations associated with chondrule formation

Chondrules are ubiquitous constituents of primitive solar system matter, indicating that chondrule formation was an important and widespread process in the early history of the solar system. If chondrules formed from fine grained CI like precursors, some volatile fractionation must have accompanied chondrule formation. This is not likely related to a separation of chondrules from gas (and dust, fine enough to be coupled to gas) shortly after formation, a process required by most models of chondrule formation. If chondrules are continuously formed in and removed from a region of the solar nebula, the chemical environment in this region will change. Vaporization of solid increases both oxygen and sulfur in the gas relative to H. Depending on the oxygen/sulfur ratio, which may vary widely as a function of precursor composition and temperature, two cases can be distinguished: (1) sulfur requires reaction with solid to condense, and thus may become much more enriched than 0; (2) if a significant amount of silicate is vaporized together with sulfides and does not recondense, changes in H/O outweigh S enrichment. In combination, these two effects may be able to account for much of the chemical variation among various types of chondrites. Opaque, fine grained matrix in unequilibrated chondrites, which is thought to derive from dust, has indeed been found to have a volatile element abundance complementary to chondrules.

Kracher, A.↗
NASA NTRS1985

Summer Arctic sea ice character from satellite microwave data

It is pointed out that Arctic sea ice and its environment undergo a number of changes during the summer period. Some of these changes affect the ice cover properties and, in turn, their response to thermal and mechanical forcing throughout the year. The main objective of this investigation is related to the development of a method for estimating the areal coverage of exposed ice, melt ponds, and leads, which are the basic surface variables determining the local surface albedo. The study is based on data obtained in a field investigation conducted from Mould Bay (NWT), Nimbus 5 satellite data, and Seasat data. The investigation demonstrates that microwave data from satellites, especially microwave brightness temperature, provide good data for estimating important characteristics of summer sea ice cover.

Carsey, F. D.↗
NASA NTRS1988

Estimating the cost of mental loading in a bimodal divided-attention task: Combining reaction time, heart-rate variability and signal-detection theory

Multiple approaches are necessary for understanding and measuring workload. In particular, physiological systems identifiable by employing cardiac measures are related to cognitive systems. One issue of debate in measuring cardiac output is the grain of analysis used in recording and summarizing data. Various experiments are reviewed, the majority of which were directed at supporting or contradicting Lacey's intake-rejection hypothesis. Two of the experiments observed heart rate in operational environments and found virtually no changes associated with mental load. The major problems facing researchers using heart rate variability, or sinus arrhthmia, as a dependent measure have been associated with valid and sensitive scoring and preventing contamination of observed results by influences unrelated to cognition. Spectral analysis of heart rate variability offers two useful procedures: analysis from the time domain and analysis from the frequency domain. Most recently, data have been collected in a divided attention experiment, the performance measures and cardiac measures of which are detailed.

Casper, Patricia A.↗
NASA NTRS1988

Contingency rescheduling of spacecraft operations

Spacecraft activity scheduling was a focus of attention in artificial intelligence recently. Several scheduling systems were devised which more-or-less successfully address various aspects of the activity scheduling problem, though most of these are not yet mature, with the notable expection of NASA's ESP. Few current scheduling systems, however, make any attempt to deal fully with the problem of modifying a schedule in near-real-time in the event of contingencies which may arise during schedule execution. These contingencies can include resources becoming unavailable unpredictably, a change in spacecraft conditions or environment, or the need to perform an activity not scheduled. In these cases it becomes necessary to repair an existing schedule, disrupting ongoing operations as little as possible. Normal scheduling is just a part of that which must be accomplished during contingency rescheduling. A prototype system named MAESTRO was developed for spacecraft activity scheduling. MAESTRO is briefly described with a focus on recent work in the area of real-time contingency handling. Included is a discussion of some of the complexities of the scheduling problem and how they affect contingency rescheduling, such as temporal constraints between activities, activities which may be interrupted and continued in any of several ways, and different ways to choose a resource complement which will allow continuation of an activity. Various heuristics used in MAESTRO for contingency rescheduling is discussed, as are operational concerns such as interaction of the scheduler with spacecraft subsystems controllers.

Britt, Daniel L.↗
NASA NTRS1987

Debarment and suspension

The changing Government attitude toward contractor debarment and suspension is examined, with emphasis on the fact that the Government is more alert to fraud, waste, and abuse. Consideration is given to causes of debarment or suspension, procedures and due process hearings, settlement agreements, compliance programs, and recent related legislation. It is concluded that the change in the Government contracting environment in recent years should be sufficient incentive for contractors to monitor their operations more closely.

Whelan, Thomas J.↗
NASA NTRS1988

The sun and the sun-earth connection

A discussion is presented of the elements comprising the field of solar-system space physics: the sun; the interplanetary medium; and the magnetosphere, ionosphere, and upper atmosphere of the earth and, to a leser extent, the planets. The principal entities in the interaction chain beginning at the center of the sun and extending through the interplanetary medium to earth's magnetosphere, ionosphere, and upper atmosphere are described with particular emphasis on solar variability and its manifestation in dynamical changes of the earth's environment. Solar variations range in time scales from less than 1 sec to over a century and can affect specific regions at earth within 8 min (solar X-ray bursts) and up to several decades (climatic variations).

Krimigis, S. M.↗
NASA NTRS1989

Ultraviolet radiation effects

Solar ultraviolet testing was not developed which will provide highly accelerated (20 to 50X) exposures that correlate to flight test data. Additional studies are required to develop an exposure methodology which will assure that accelerated testing can be used for qualification of materials and coatings for long duration space flight. Some conclusions are listed: Solar UV radiation is present in all orbital environments; Solar UV does not change in flux with orbital altitude; UV radiation can degrade most coatings and polymeric films; Laboratory UV simulation methodology is needed for accelerated testing to 20 UV solar constants; Simulation of extreme UV (below 200 nm) is needed to evaluate requirements for EUV in solar simulation.

Slemp, Wayne S.↗
NASA NTRS1991

Volumetric measurement of tank volume

A method is disclosed for determining the volume of compressible gas in a system including incompressible substances in a zero-gravity environment consisting of measuring the change in pressure (delta P) for a known volume change rate (delta V/delta t) in the polytrophic region between isothermal and adiabatic conditions. The measurements are utilized in an idealized formula for determining the change in isothermal pressure (delta P sub iso) for the gas. From the isothermal pressure change (delta iso) the gas volume is obtained. The method is also applicable to determination of gas volume by utilizing work (W) in the compression process. In a passive system, the relationship of specific densities can be obtained.

Walter, Richard T.↗
NASA NTRS1991

SHARP: Spacecraft Health Automated Reasoning Prototype

The planetary spacecraft mission OPS as applied to SHARP is studied. Knowledge systems involved in this study are detailed. SHARP development task and Voyager telecom link analysis were examined. It was concluded that artificial intelligence has a proven capability to deliver useful functions in a real time space flight operations environment. SHARP has precipitated major change in acceptance of automation at JPL. The potential payoff from automation using AI is substantial. SHARP, and other AI technology is being transferred into systems in development including mission operations automation, science data systems, and infrastructure applications.

Atkinson, David J.↗
NASA NTRS1991

Mission to Planet Earth

The NASA program described is an international study to predict changes in the earth's environment by means of multidisciplinary remote sensing from satellites. An international consortium dedicates satellites with advanced sensors to data collection, and a data processing system is described to collect and analyze a large amount of terrestrial data. The program requires international multidisciplinary involvement to collect and interpret the data and thereby manage and preserve the global environment.

Tilford, Shelby G.↗
NASA NTRS1992

Mission to Planet Earth

Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the earth and how it works as a system. Increased understanding of the earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

Wilson, Gregory S.↗
NASA NTRS1992

Shuttle Imaging Radar-C mission operations - Technology test bed for Earth Observing System synthetic aperture radar

The mission operations for the Space Radar Lab (SRL), particularly in the areas of real-time replanning and science activity coordination, are presented. The two main components of SRL are the Shuttle Imaging Radar-C and the X-Band Synthetic Aperture Radar. The Earth Observing System SAR will be a multispectral, multipolarization radar satellite that will provide information over an entire decade, permitting scientists to monitor large-scale changes in the earth's environment over a long period of time.

Trimble, J. P.↗
NASA NTRS1992

Heat pipe fatigue test specimen: Metallurgical evaluation

An innovative creep/fatigue test was run to simulate the temperature, mechanical load, and sodium corrosion conditions expected in a heat pipe designed to supply thermal energy to a Stirling cycle power converter. A sodium-charged Inconel 718 heat pipe with a Nickel 200 screen wick was operated for 1090 hr at temperatures between 950 K (1250 F) and 1050 K (1430 F) while being subjected to creep and fatigue loads in a servo-hydraulic testing machine. After testing, the heat pipe was sectioned and examined using optical microscopy, scanning electron microscopy, and electron microprobe analysis with wavelength dispersive x-ray spectroscopy. The analysis concentrated on evaluating topographic, microstructural, and chemical changes in the sodium exposed surfaces of the heat pipe wall and wick. Surface changes in the evaporator, condenser, and adiabatic sections of the heat pipe were examined in an effort to correlate the changes with the expected sodium environment in the heat pipe. This report describes the setup, operating conditions, and analytical results of the sodium heat pipe fatigue test.

Walak, Steven E.↗
NASA NTRS1992

Mission to Planet Earth

Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment. An overview of the MTPE, flight programs, data and information systems, interdisciplinary research efforts, and international coordination, is presented.

Wilson, Gregory S.↗
NASA NTRS1994

Advanced teleoperation: Technology innovations and applications

The capability to remotely, robotically perform space assembly, inspection, servicing, and science functions would rapidly expand our presence in space, and the cost efficiency of being there. There is considerable interest in developing 'telerobotic' technologies, which also have comparably important terrestrial applications to health care, underwater salvage, nuclear waste remediation and other. Such tasks, both space and terrestrial, require both a robot and operator interface that is highly flexible and adaptive, i.e., capable of efficiently working in changing and often casually structured environments. One systems approach to this requirement is to augment traditional teleoperation with computer assists -- advanced teleoperation. We have spent a number of years pursuing this approach, and highlight some key technology developments and their potential commercial impact. This paper is an illustrative summary rather than self-contained presentation; for completeness, we include representative technical references to our work which will allow the reader to follow up items of particular interest.

Schenker, Paul S.↗
NASA NTRS1994

From neural-based object recognition toward microelectronic eyes

Engineering neural network systems are best known for their abilities to adapt to the changing characteristics of the surrounding environment by adjusting system parameter values during the learning process. Rapid advances in analog current-mode design techniques have made possible the implementation of major neural network functions in custom VLSI chips. An electrically programmable analog synapse cell with large dynamic range can be realized in a compact silicon area. New designs of the synapse cells, neurons, and analog processor are presented. A synapse cell based on Gilbert multiplier structure can perform the linear multiplication for back-propagation networks. A double differential-pair synapse cell can perform the Gaussian function for radial-basis network. The synapse cells can be biased in the strong inversion region for high-speed operation or biased in the subthreshold region for low-power operation. The voltage gain of the sigmoid-function neurons is externally adjustable which greatly facilitates the search of optimal solutions in certain networks. Various building blocks can be intelligently connected to form useful industrial applications. Efficient data communication is a key system-level design issue for large-scale networks. We also present analog neural processors based on perceptron architecture and Hopfield network for communication applications. Biologically inspired neural networks have played an important role towards the creation of powerful intelligent machines. Accuracy, limitations, and prospects of analog current-mode design of the biologically inspired vision processing chips and cellular neural network chips are key design issues.

Sheu, Bing J.↗