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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 451 records · Page 25

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NASA NTRS1987

Earth resources: A continuing bibliography with indexes (issue 54)

This bibliography lists 562 reports, articles, and other documents introduced into the NASA scientific and technical information system between April 1 and June 30, 1987. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

Source record↗

NASA NTRS1987

Earth resources: A continuing bibliography with indexes (issue 55)

This bibliography lists 368 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1 and September 30, 1987. Emphasis is placed on the use of remote sensing and geographical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

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NASA NTRS1987

File Usage Analysis and Resource Usage Prediction: a Measurement-Based Study

A probabilistic scheme was developed to predict process resource usage in UNIX. Given the identity of the program being run, the scheme predicts CPU time, file I/O, and memory requirements of a process at the beginning of its life. The scheme uses a state-transition model of the program's resource usage in its past executions for prediction. The states of the model are the resource regions obtained from an off-line cluster analysis of processes run on the system. The proposed method is shown to work on data collected from a VAX 11/780 running 4.3 BSD UNIX. The results show that the predicted values correlate well with the actual. The coefficient of correlation between the predicted and actual values of CPU time is 0.84. Errors in prediction are mostly small. Some 82% of errors in CPU time prediction are less than 0.5 standard deviations of process CPU time.

Devarakonda, Murthy V.-S.↗

NASA NTRS1987

Predictability of process resource usage: A measurement-based study of UNIX

A probabilistic scheme is developed to predict process resource usage in UNIX. Given the identity of the program being run, the scheme predicts CPU time, file I/O, and memory requirements of a process at the beginning of its life. The scheme uses a state-transition model of the program's resource usage in its past executions for prediction. The states of the model are the resource regions obtained from an off-line cluster analysis of processes run on the system. The proposed method is shown to work on data collected from a VAX 11/780 running 4.3 BSD UNIX. The results show that the predicted values correlate well with the actual. The correlation coefficient between the predicted and actual values of CPU time is 0.84. Errors in prediction are mostly small. Some 82% of errors in CPU time prediction are less than 0.5 standard deviations of process CPU time.

Devarakonda, Murthy V.↗

NASA NTRS1988

Earth resources: A continuing bibliography with indexes (supplement 56)

This bibliography lists 547 reports, articles, and other documents introduced into the NASA scientific and technical information system between October 1 and December 31, 1987. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

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NASA NTRS1988

Earth resources: A continuing bibliography with indexes (issue 57)

This bibliography lists 451 reports, articles and other documents introduced into the NASA scientific and technical information system between January 1 and March 31, 1988. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

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NASA NTRS1988

Optimal use of human and machine resources for Space Station assembly operations

This paper investigates the issues involved in determining the best mix of human and machine resources for assembly of the Space Station. It presents the current Station assembly sequence, along with descriptions of the available assembly resources. A number of methodologies for optimizing the human/machine tradeoff problem have been developed, but the Space Station assembly offers some unique issues that have not yet been addressed. These include a strong constraint on available EVA time for early flights and a phased deployment of assembly resources over time. A methodology for incorporating the previously developed decision methods to the special case of the Space Station is presented. This methodology emphasizes an application of multiple qualitative and quantitative techniques, including simulation and decision analysis, for producing an objective, robust solution to the tradeoff problem.

Parrish, Joseph C.↗

NASA NTRS1987

Deep space network resource scheduling approach and application

Deep Space Network (DSN) resource scheduling is the process of distributing ground-based facilities to track multiple spacecraft. The Jet Propulsion Laboratory has carried out extensive research to find ways of automating this process in an effort to reduce time and manpower costs. This paper presents a resource-scheduling system entitled PLAN-IT with a description of its design philosophy. The PLAN-IT's current on-line usage and limitations in scheduling the resources of the DSN are discussed, along with potential enhancements for DSN application.

Eggemeyer, William C.↗

NASA NTRS1987

Space station Platform Management System (PMS) replanning using resource envelopes

One of the responsibilities of the Space Station Platform Management System (PMS) is to maintain constraint-free, short-term plans for platform and free-flyer activities. Both the replanning function and the associated constraint-checking function are viewed as potentially requiring expert system assistance. The PMS Resource Envelope Scheduling System (PRESS) expert system, which is currently under development, is described. The PRESS capabilities will include the following: plan, replan, and perform constraint checking using resource envelopes resembling those required for telescience; initialize itself using the results fo a previous run; infer the replanning needs associated with a change in resource availability; allow the user to determine the level of interaction (including an advisory capability) with the system during execution; and generate both a graphic timeline and a report as output. The PRESS is being developed on an IBM PC/AT using TeKnowledge, Inc.'s M.1 expert system shell. The PRESS activity definitions and constraints are based on those defined for the Cosmic Background Explorer (COBE) mission scheduled for launch in early 1989.

Bush, Joy Lee↗

NASA NTRS1988

Earth resources: A continuing bibliography with indexes (issue 58)

This bibliography lists 500 reports, articles, and other documents introduced into the NASA scientific and technical information system between April 1 and June 30, 1988. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

Source record↗

NASA NTRS1988

Earth resources: A continuing bibliography with indexes (issue 62)

This bibliography lists 544 reports, articles, and other documents introduced into the NASA scientific and technical information system between April 1 and June 30, 1989. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

Source record↗

NASA NTRS1988

An analysis of possible advanced space strategies featuring the role of space resource utilization

Unresolved issues in space planning in the U.S. are examined, focusing on space resource utilization. The role of the Space Station, determining the most profitable space exploration strategies, and space resource use are discussed. Performance modeling suggests that lunar oxygen is useful on the moon and economical in LEO if lunar hydrogen is available. It is found that the use of volatile materials from Phobos and Deimos might be undertaken if lunar hydrogen is unavailable. It is suggested that resource synergisms between operations in the Mars system and in earth-moon space have important commercial possibilities.

Cordell, Bruce↗

NASA NTRS1990

Resource allocation using constraint propagation

The concept of constraint propagation was discussed. Performance increases are possible with careful application of these constraint mechanisms. The degree of performance increase is related to the interdependence of the different activities resource usage. Although this method of applying constraints to activities and resources is often beneficial, it is obvious that this is no panacea cure for the computational woes that are experienced by dynamic resource allocation and scheduling problems. A combined effort for execution optimization in all areas of the system during development and the selection of the appropriate development environment is still the best method of producing an efficient system.

Rogers, John S.↗

NASA NTRS1989

A system management methodology for building successful resource management systems

This paper presents a system management methodology for building successful resource management systems that possess lifecycle effectiveness. This methodology is based on an analysis of the traditional practice of Systems Engineering Management as it applies to the development of resource management systems. The analysis produced fifteen significant findings presented as recommended adaptations to the traditional practice of Systems Engineering Management to accommodate system development when the requirements are incomplete, unquantifiable, ambiguous and dynamic. Ten recommended adaptations to achieve operational effectiveness when requirements are incomplete, unquantifiable or ambiguous are presented and discussed. Five recommended adaptations to achieve system extensibility when requirements are dynamic are also presented and discussed. The authors conclude that the recommended adaptations to the traditional practice of Systems Engineering Management should be implemented for future resource management systems and that the technology exists to build these systems extensibly.

Hornstein, Rhoda Shaller↗

NASA NTRS1989

A 'figure-of-merit' approach to extraterrestrial resource utilization

An approach for interrelated optimizations in space missions that utilize extraterrestrial resources is developed, consisting in the concept of an overall mission 'figure-of-merit' leading to more realistic designs than through individual performance maximizations. After a brief discussion of this concept, the synthesis of four major components of any future space mission is considered. The four major components are: orbital mechanics of the transportation; performance of the rocket motors; support systems including power, thermal and process controls, and instruments; and in situ resource utilization plant equipment. The Mars Sample Return mission is the basis of an illustration of the proposed concept. A popular spreadsheet is used to quantitatively demonstrate the interdependent nature of the mission optimization. Future prospects are outlined, that promise great economy through extraterrestrial resource utilization and a quick evaluation technique.

Ramohalli, Kumar↗

NASA NTRS1989

Predictability of process resource usage - A measurement-based study on UNIX

A probabilistic scheme is developed to predict process resource usage in UNIX. Given the identity of the program being run, the scheme predicts CPU time, file I/O, and memory requirements of a process at the beginning of its life. The scheme uses a state-transition model of the program's resource usage in its past executions for prediction. The states of the model are the resource regions obtained from an off-line cluster analysis of processes run on the system. The proposed method is shown to work on data collected from a VAX 11/780 running 4.3 BSD UNIX. The results show that the predicted values correlate well with the actual. The correlation coefficient betweeen the predicted and actual values of CPU time is 0.84. Errors in prediction are mostly small. Some 82 percent of errors in CPU time prediction are less than 0.5 standard deviations of process CPU time.

Devarakonda, Murthy V.↗

NASA NTRS1990

A figure-of-merit approach to extraterrestrial resource utilization

A concept is developed for interrelated optimizations in space missions that utilize extraterrestrial resources. It is shown that isolated (component) optimizations may not result in the best mission. It is shown that substantial benefits can be had through less than the best propellants, propellant combinations, propulsion hardware, and actually, some waste in the traditional sense. One ready example is the possibility of discarding hydrogen produced extraterrestrially by water splitting and using only the oxygen to burn storable fuels. The gains in refrigeration and leak-proof equipment mass (elimination) outweigh the loss in specific impulse. After a brief discussion of this concept, the synthesis of the four major components of any future space mission is developed. The four components are: orbital mechanics of the transportation; performance of the rocket motor; support systems that include power; thermal and process controls, and instruments; and in situ resource utilization plant equipment. This paper's main aim is to develop the concept of a figure-of-merit for the mission. The Mars Sample Return Mission is used to illustrate the new concept. At this time, a popular spreadsheet is used to quantitatively indicate the interdependent nature of the mission optimization. Future prospects are outlined that promise great economy through extraterrestrial resource utilization and a technique for quickly evaluating the same.

Ramohalli, K.↗

NASA NTRS1991

Refractory materials from lunar resources

Refractories - materials which are able to withstand extremely high temperatures - are sure to be an important part of any processing facility or human outpost which is built on Mars. Containers for processing lunar oxygen will need high temperature components. Fabrication of structural material from lunar resources need both containment vessels to hold high temperature melts and molds in which to form the final shapes. Certainly, it would be desirable to fabricate such vessels and molds on the Moon, rather than carrying them up from the Earth. At first glance, this might appear to be a trivial task, since the Moon's surface consists of a variety of refractory compositions. To turn the regolith into a useful fire brick or mold, however, will require water or other binders and additives which are likely to be in extremely short supply on the Moon. The steps needed to make fire bricks and molds for lunar-derived structural materials are examined, pointing out the critical steps and resources which will be needed. While these processes and applications may seem somewhat mundane, it is emphasized that it is precisely these rudimentary processes which must be mastered before discussing making aerobrakes, and other fancier refractories from lunar resources.

Fabes, B. D.↗