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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

The elements of a space operations system

The Space Shuttle has completed its flight test program and is entering operational service with its fifth flight in November 1982. With the completion of Shuttle development, its entry to operational service, and delivery of additional units into field service, it is timely to initiate development of the next elements of the system. The elements of a Space Operations System are the Shuttle, a Station in low earth orbit, and upper stages for low and high energy orbit delivery. To design these elements properly will require a substantial operations analysis effort to characterize the most effective performance tradeoffs among the discrete elements. The Shuttle establishes a new context for the design and execution of operations in space. The components of the Shuttle, Space Station, and upper stages will need to share technology and components to minimize the cost and complexity of the logistics of ownership and operation.

Loftus, J. P., Jr.↗
NASA NTRS1982

The Ruggedized STD Bus Microcomputer - A low cost computer suitable for Space Shuttle experiments

Previous space flight computers have been costly in terms of both hardware and software. The Ruggedized STD Bus Microcomputer is based on the commercial Mostek/Pro-Log STD Bus. Ruggedized PC cards can be based on commercial cards from more than 60 manufacturers, reducing hardware cost and design time. Software costs are minimized by using standard 8-bit microprocessors and by debugging code using commercial versions of the ruggedized flight boards while the flight hardware is being fabricated.

Budney, T. J.↗
NASA NTRS1982

Antenna optimization of single beam microwave systems for the solar power satellite

A generalized antenna design technique is applied to the unique environmental requirements pertaining to solar power satellite (SPS) systems. Optimal illumination tapers and antenna/rectenna sizings are generated which allow increased transmit powers and lower electricity costs while minimizing sidelobe levels to meet a 0.01 mW/sq cm environmental standard. These optimal tapers also provide other advantages over the 10 dB Gaussian reference system.

Kerwin, E. M.↗
NASA NTRS1983

Implementation Strategy

Meeting the identified needs of Earth science requires approaching EOS as an information system and not simply as one or more satellites with instruments. Six elements of strategy are outlined as follows: implementation of the individual discipline missions as currently planned; use of sustained observational capabilities offered by operational satellites without waiting for the launch of new mission; put first priority on the data system; deploy an Advanced Data Collection and Location System; put a substantial new observing capability in a low Earth orbit in such a way as to provide for sustained measurements; and group instruments to exploit their capabilities for synergism; maximize the scientific utility of the mission; and minimize the costs of implementation where possible.

Source record↗
NASA NTRS1985

The application of artificial intelligence techniques to large distributed networks

Data accessibility and transfer of information, including the land resources information system pilot, are structured as large computer information networks. These pilot efforts include the reduction of the difficulty to find and use data, reducing processing costs, and minimize incompatibility between data sources. Artificial Intelligence (AI) techniques were suggested to achieve these goals. The applicability of certain AI techniques are explored in the context of distributed problem solving systems and the pilot land data system (PLDS). The topics discussed include: PLDS and its data processing requirements, expert systems and PLDS, distributed problem solving systems, AI problem solving paradigms, query processing, and distributed data bases.

Dubyah, R.↗
NASA NTRS1984

Optimal inventories for overhaul of repairable redundant systems - A Markov decision model

A Markovian decision model was developed to calculate the optimal inventory of repairable spare parts for an avionics control system for commercial aircraft. Total expected shortage costs, repair costs, and holding costs are minimized for a machine containing a single system of redundant parts. Transition probabilities are calculated for each repair state and repair rate, and optimal spare parts inventory and repair strategies are determined through linear programming. The linear programming solutions are given in a table.

Schaefer, M. K.↗
NASA NTRS1985

Application of modern tools and techniques to maximize engineering productivity in the development of orbital operations plans for the space station progrm

The Space Station Program will incorporate analysis of operations constraints and considerations in the early design phases to avoid the need for later modifications to the Space Station for operations. The application of modern tools and administrative techniques to minimize the cost of performing effective orbital operations planning and design analysis in the preliminary design phase of the Space Station Program is discussed. Tools and techniques discussed include: approach for rigorous analysis of operations functions, use of the resources of a large computer network, and providing for efficient research and access to information.

Manford, J. S.↗
NASA NTRS1986

Integration of an expert system into a user interface language demonstration

The need for a User Interface Language (UIL) has been recognized by the Space Station Program Office as a necessary tool to aid in minimizing the cost of software generation by multiple users. Previous history in the Space Shuttle Program has shown that many different areas of software generation, such as operations, integration, testing, etc., have each used a different user command language although the types of operations being performed were similar in many respects. Since the Space Station represents a much more complex software task, a common user command language--a user interface language--is required to support the large spectrum of space station software developers and users. To assist in the selection of an appropriate set of definitions for a UIL, a series of demonstration programs was generated with which to test UIL concepts against specific Space Station scenarios using operators for the astronaut and scientific community. Because of the importance of expert system in the space station, it was decided that an expert system should be embedded in the UIL. This would not only provide insight into the UIL components required but would indicate the effectiveness with which an expert system could function in such an environment.

Stclair, D. C.↗
NASA NTRS1986

Electrical power system for the U.S. space station

The Space Station Electrical Power System presents many interesting challenges. It will be much larger than previous space power systems, and it must be designed for on-orbit maintenance and replacement, along with having a growth capability. The power generation, energy storage, and power management and distribution (PMAD) subsystems comprise the primary elements of the overall system. Each was analyzed by NASA Lewis Research Center and its two contractors -- Rocketdyne and TRW -- in the definition studies of the program to determine the optimum approach to minimize initial costs and life cycle costs. For the PMAD subsystem, a ring bus architecture operating at 440 V, 20 kHz, single phase, was selected. Photovoltaic and solar dynamic power generation subsystems were both studied. Major tradeoffs were made for each subsystem and for the overall system, and a hybrid system (both photovoltaic and solar dynamic) was selected.

Nored, D. L.↗
NASA NTRS1986

Electrical power system for the U.S. Space Station

The Space Station Electrical Power System presents many interesting challenges. It will be much larger than previous space power systems, and it must be designed for on-orbit maintenance and replacement, along with having a growth capability. The power generation, energy storage, and power management and distribution (PMAD) subsystems comprise the primary elements of the overall system. Each was analyzed by NASA Lewis Research Center and its two contractors Rocketdyne and TRW - in the definition studies of the program to determine the optimum approach to minimize initial costs and life cycle costs. For the PMAD subsystem, a ring bus architecture operating at 440 V, 20 kHz, single phase, was selected. Photovoltaic and solar dynamic power generation subsystems were both studied. Major tradeoffs were made for each subsystem and for the overall system, and a hybrid system (both photovoltaic and solar dynamic) was selected.

Nored, D. L.↗
NASA NTRS1986

Affordable solar system exploration

The design features of the Comet Rendezvous Asteroid Flyby (CRAF) version of the Mariner Mark II spacecraft are described, together with the instruments to be carried aboard and the goals of the mission. To minimize the cost, computer-aided design, engineering, and manufacturing will be used, and, where possible, established technologies and off-the- shelf products will be incorporated. Planned for a launch in 1992, the CRAF will rendezvous with the Tempel 2 comet in 1996 and will stick with it through 1999, making studies of plasma in the comet's coma and the comet's dust, gas, and nucleus by means of its penetrator rocket which will pierce the nucleus.

Draper, Ronald F.↗
NASA NTRS1987

Real-time operational planning for the U.S. air traffic system

This paper describes an integrated planning model for the U.S. air traffic system. The approach incorporates the dual objectives of monitoring collision risk while minimizing transportation costs. Specialized solution algorithms exploit the underlying structure of the model - especially for large-scale examples. The proposed formulation is tested with real-world data for the Indianapolis control sector. Additional experiments with a CRAY X-MP/24 supercomputer show that a full-scale model can be solved under real time conditions. Despite these advances, additional work is required in developing a practical system. Suggestions are made for combining advances in computer graphics and mathematical modeling.

Mulvey, John M.↗
NASA NTRS1987

Fault protection design for unmanned interplanetary spacecraft

The difficulties encountered in designing a redundancy management system are discussed and strategies for minimizing the cost and schedule impacts associated with fault protection are provided. Specific examples from the Magellan project are used with emphasis placed on control system fault protection. The major problem areas are the following: (1) the interaction between two semiindependent fault protection systems, (2) the response to faults which are detected by monitoring variables with long time constants, and (3) the design of the 'action scheduler'.

Johnson, Stephen B.↗
NASA NTRS1988

Accurate modeling of parallel scientific computations

Scientific codes are usually parallelized by partitioning a grid among processors. To achieve top performance it is necessary to partition the grid so as to balance workload and minimize communication/synchronization costs. This problem is particularly acute when the grid is irregular, changes over the course of the computation, and is not known until load time. Critical mapping and remapping decisions rest on the ability to accurately predict performance, given a description of a grid and its partition. This paper discusses one approach to this problem, and illustrates its use on a one-dimensional fluids code. The models constructed are shown to be accurate, and are used to find optimal remapping schedules.

Nicol, David M.↗
NASA NTRS1987

SAR image data compression for an on-line archive system

This paper summarizes the investigation of SAR image data compression for an on-line archive data distribution system. This system is planned for the ground processing system of Alaska SAR Facility (ASF) and Shuttle Imaging Radar (SIR-C). The objective of the SAR image data compression is to enable the data archive system to provide the remote users a large data base with good image quality, short response time, low transfer cost, and minimal decoding complexity. The requirements and limitations of the on-line archive data distribution system are presented. The effects of SAR image data characteristics on data compression are addressed. The users' survey results suggest that compression ratios between 10:1 and 20:1 appear suitable. Based on the algorithm evaluation results, the two-level tree-searched vector quantization technique has been recommended as the SAR image data compression algorithm for the on-line archive data distribution system.

Chang, C. Y.↗
NASA NTRS1988

A Saturn atmospheric probe - A proposed augmentation to the Cassini mission

The Saturn probe augmentation of the Cassini mission is studied with particular attention given to the scientific rationale for such an augmentation and any associated issues of technical feasibility, system requirements, performance penalties, and costs. A minimal science complement probe, which concentrates only on atmospheric composition and structure with a total mass requirement of slightly less than 200 kg, is described as well as a full science complement probe with a total mass requirement of about 240 kg. It is noted that either of these Saturn probe configurations can be added to the currently planned mission within the launch performance limitations of the Titan 34D7/Centaur G(prime) launch vehicle.

Swenson, Byron L.↗
NASA NTRS1988

Computing motion using resistive networks

Recent developments in the theory of early vision are described which lead from the formulation of the motion problem as an ill-posed one to its solution by minimizing certain 'cost' functions. These cost or energy functions can be mapped onto simple analog and digital resistive networks. It is shown how the optical flow can be computed by injecting currents into resistive networks and recording the resulting stationary voltage distribution at each node. These networks can be implemented in cMOS VLSI circuits and represent plausible candidates for biological vision systems.

Koch, Christof↗
NASA NTRS1989

A variable-gain output feedback control design approach

A multi-model design technique to find a variable-gain control law defined over the whole operating range is proposed. The design is formulated as an optimal control problem which minimizes a cost function weighing the performance at many operating points. The solution is obtained by embedding into the Multi-Configuration Control (MCC) problem, a multi-model robust control design technique. In contrast to conventional gain scheduling which uses a curve fit of single model designs, the optimal variable-gain control law stabilizes the plant at every operating point included in the design. An iterative algorithm to compute the optimal control gains is presented. The methodology has been successfully applied to reconfigurable aircraft flight control and to nonlinear flight control systems.

Haylo, Nesim↗