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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Atmospheric concentrations and behavior of halocarbons and methane

The atmospheric concentrations of halocarbons and methane in the troposphere and stratosphere were precisely measured by grab-sampling followed by gas-chromatographic analysis in the laboratory. Chlorofluorocarbons such as CCl2F2 and CCl3F have received a great deal of attention due to their probable impact on the stratospheric ozone: the chlorofluorocarbons accumulated in the troposphere are eventually decomposed by photolysis in the stratosphere releasing Cl radicals which in turn participate in the ClO sub x-catalytic chain destroying the ozone, especially in the upper stratosphere. Methane reacts with Cl in the stratosphere reducing the ozone depletion, while its source and future trend of concentration in the troposphere are uncertain. The study of their distribution and behavior in the atmosphere are therefore very important. After the extensive survey of the locations for collection of atmospheriic samples representing the midlatitudes Northern Hemisphere (N.H.) without local contamination, we have measured the concentrations of CCl2F2, CCl3F, CH3CCl3, CC1, CHCl=CCl2 and CCl2=CCl2 with plus or minus 1 pptv precision in samples collected in Hokkaido and west coast Tohoku area (the northern part of Japan, 40 deg to 45 deg N) every summer and winter since 1979. The observed concentrations of CCl2F2 and CCl3F are now above 360 and 200 pptv, respectively, and have been steadily increasing by approx. 15 and approx. 8 pptv/year during the last several years.

Makide, Y.↗
NASA NTRS1986

Optimal design of structures with multiple design variables per group and multiple loading conditions on the personal computer

A finite element based programming system for minimum weight design of a truss-type structure subjected to displacement, stress, and lower and upper bounds on design variables is presented. The programming system consists of a number of independent processors, each performing a specific task. These processors, however, are interfaced through a well-organized data base, thus making the tasks of modifying, updating, or expanding the programming system much easier in a friendly environment provided by many inexpensive personal computers. The proposed software can be viewed as an important step in achieving a 'dummy' finite element for optimization. The programming system has been implemented on both large and small computers (such as VAX, CYBER, IBM-PC, and APPLE) although the focus is on the latter. Examples are presented to demonstrate the capabilities of the code. The present programming system can be used stand-alone or as part of the multilevel decomposition procedure to obtain optimum design for very large scale structural systems. Furthermore, other related research areas such as developing optimization algorithms (or in the larger level: a structural synthesis program) for future trends in using parallel computers may also benefit from this study.

Nguyen, D. T.↗
NASA NTRS1985

Progress and supercomputing in computational fluid dynamics; Proceedings of U.S.-Israel Workshop, Jerusalem, Israel, December 1984

Current developments and future trends in the application of supercomputers to computational fluid dynamics are discussed in reviews and reports. Topics examined include algorithm development for personal-size supercomputers, a multiblock three-dimensional Euler code for out-of-core and multiprocessor calculations, simulation of compressible inviscid and viscous flow, high-resolution solutions of the Euler equations for vortex flows, algorithms for the Navier-Stokes equations, and viscous-flow simulation by FEM and related techniques. Consideration is given to marching iterative methods for the parabolized and thin-layer Navier-Stokes equations, multigrid solutions to quasi-elliptic schemes, secondary instability of free shear flows, simulation of turbulent flow, and problems connected with weather prediction.

Murman, E. M.↗
NASA NTRS1986

Physics through the 1990s: Scientific interfaces and technological applications

The volume examines the scientific interfaces and technological applications of physics. Twelve areas are dealt with: biological physics-biophysics, the brain, and theoretical biology; the physics-chemistry interface-instrumentation, surfaces, neutron and synchrotron radiation, polymers, organic electronic materials; materials science; geophysics-tectonics, the atmosphere and oceans, planets, drilling and seismic exploration, and remote sensing; computational physics-complex systems and applications in basic research; mathematics-field theory and chaos; microelectronics-integrated circuits, miniaturization, future trends; optical information technologies-fiber optics and photonics; instrumentation; physics applications to energy needs and the environment; national security-devices, weapons, and arms control; medical physics-radiology, ultrasonics, MNR, and photonics. An executive summary and many chapters contain recommendations regarding funding, education, industry participation, small-group university research and large facility programs, government agency programs, and computer database needs.

Source record↗
NASA NTRS1987

Vortical flow aerodynamics - Physical aspects and numerical simulation

Progress in the numerical simulation of vortical flow due to three-dimensional flow separation about flight vehicles at high angles of attack and quasi-steady flight conditions is surveyed. Primary emphasis is placed on Euler and Reynolds-averaged Navier-Stokes methods where the vortices are 'captured' as a solution to the governing equations. A discussion of the relevant flow physics provides a perspective from which to assess numerical solutions. Current numerical prediction capabilities and their evolutionary development are surveyed. Future trends and challenges are identified and discussed.

Newsome, Richard W.↗
NASA NTRS1987

Expert system technology

The expert system is a computer program which attempts to reproduce the problem-solving behavior of an expert, who is able to view problems from a broad perspective and arrive at conclusions rapidly, using intuition, shortcuts, and analogies to previous situations. Expert systems are a departure from the usual artificial intelligence approach to problem solving. Researchers have traditionally tried to develop general modes of human intelligence that could be applied to many different situations. Expert systems, on the other hand, tend to rely on large quantities of domain specific knowledge, much of it heuristic. The reasoning component of the system is relatively simple and straightforward. For this reason, expert systems are often called knowledge based systems. The report expands on the foregoing. Section 1 discusses the architecture of a typical expert system. Section 2 deals with the characteristics that make a problem a suitable candidate for expert system solution. Section 3 surveys current technology, describing some of the software aids available for expert system development. Section 4 discusses the limitations of the latter. The concluding section makes predictions of future trends.

Prince, Mary Ellen↗
NASA NTRS1988

The potential impact of MMICs on future satellite communications

This is the Final Report representing the results of a 17-month study on the future trends and requirements of Monolithic Microwave Integrated Circuits (MMIC) for space communication applications. Specifically this report identifies potential space communication applications of MMICs, assesses the impact of MMIC on the classes of systems that were identified, determines the present status and probable 10-year growth in capability of required MMIC and competing technologies, identifies the applications most likely to benefit from further MMIC development and presents recommendations for NASA development activities to address the needs of these applications.

Dunn, Vernon E.↗
NASA NTRS1988

The potential impact of MMICs on future satellite communications: Executive summary

This Executive Summary presents the results of a 17-month study on the future trends and requirments for Monolithic Microwave Integrated circuits (MMIC) for space communication application. Specifically this report identifies potential space communication applications of MMICs, assesses the impact of MMIC on the classes of systems that were identified, determines the present status and probable 10-year growth in capability of required MMIC and competing technologies, identifies the applications most likely to benefit from further MMIC development, and presents recommendations for NASA development activities to address the needs of these applications.

Dunn, Vernon E.↗
NASA NTRS1989

Discussion of turbulence modelling: Past and future

The full text of a paper presented at the Whither Turbulence Workshop (Cornell University, March 22-24, 1989) on past and future trends in turbulence modeling is provided. It is argued that Reynolds stress models are likely to remain the preferred approach for technological applications for at least the next few decades. In general agreement with the Launder position paper, it is further argued that among the variety of Reynolds stress models in use, second-order closures constitute by far the most promising approach. However, some needed improvements in the specification of the turbulent length scale are emphasized. The central points of the paper are illustrated by examples from homogeneous turbulence.

Speziale, Charles G.↗
NASA NTRS1988

Future directions in technology development - Increased use of space as a facility

As human activities in space continue to grow in size and scope, the role of in-space technology experiments, as a necessary tool for essential technological development, will also grow. NASA has recognized the increasing importance of such experiments, and has instituted programs to plan, organize, and coordinate future in-space technology experiment activities within the overall space community. This paper discusses the history of in-space technology experiments, and expected future trends. It also describes NASA activities in this growing area of experimentation, and provides several examples of such experiments.

Ambrus, Judith H.↗
NASA NTRS1988

Spacecraft electronics design for radiation tolerance

Current design practices are described and future trends in spacecraft electronics which are likely to alter traditional approaches are discussed. A summary of radiation effects and radiation tolerance requirements typically levied on spacecraft designs is provided. Methods of dealing with radiation and testability issues are considered.

Rasmussen, Robert D.↗
NASA NTRS1988

Human workload in aviation

The application of human-factors analysis techniques to the evaluation of aircraft-crew workloads is discussed in an introductory overview. Consideration is given to the importance of workload for safety, crew size, automation, and certification; the definition and measurement of workload, physical vs mental workloads, subjective ratings, secondary tasks, biocybernetic measures, and attention and workload. Recent studies of pilot and ATC workloads are reviewed, and typical data are presented in graphs. Future trends are discussed, and it is predicted that increased cockpit automation will eventually require new methods to maintain operator attention rather than reduce workload.

Kantowitz, Barry H.↗
NASA NTRS1990

Legal ramifications of intellectual property

Recent government policy changes that have resulted in encouraging or requiring increased intellectual property rights of Federally funded research and development activities are examined. The reasons for these changes are discussed, including considerations related to technology transfer, patent rights, copyrights, trade secrets, and computer software issues. The effect of these changes on traditional approaches to the dissemination of Federally funded scientific and technical information is considered and predictions concerning future trends in intellectual property rights are given.

Kempf, Robert F.↗
NASA NTRS1990

Legal ramifications of intellectual property

Recent government policy changes that have resulted in encouraging or requiring increased intellectual property rights of federally funded research and development activities are examined. The reasons for these changes are discussed, including considerations related to technology transfer, patent rights, copyrights, trade secrets, and computer software issues. The effect of these changes on traditional approaches to the dissemination of federally funded scientific and technical information is considered and predictions concerning future trends in intellectual property rights are given.

Kempf, Robert F.↗
NASA NTRS1990

Computation of instability and transition

The state of transition calculations in 1989 and desirable future trends are analyzed within the framework of aeronautical applications with emphasis on wall-bounded flows. A shift to studies of the early stages of transition, particularly to receptivity, from studies of the late stages in excessively confined periodic domains is proposed. It is pointed out that early-stage studies require a larger computational domain and more difficult boundary conditions but not a very fine grid. Intermediate strategies, more involved than the classical Orr-Sommerfeld equation but much more economical than full Navier-Stokes equations, are emphasized, along with the need for compressible calculations.

Spalart, P. R.↗
NASA NTRS1992

On computational methods for crashworthiness

The evolution of computational methods for crashworthiness and related fields is described and linked with the decreasing cost of computational resources and with improvements in computation methodologies. The latter includes more effective time integration procedures and more efficient elements. Some recent developments in methodologies and future trends are also summarized. These include multi-time step integration (or subcycling), further improvements in elements, adaptive meshes, and the exploitation of parallel computers.

Belytschko, T.↗
NASA NTRS1992

Space commerce in a global economy - Comparison of international approaches to commercial space

A historical perspective, current status, and comparison of national government/commercial space industry relationships in the United States and Europe are presented. It is noted that space technology has been developed and used primarily to meet the needs of civil and military government initiatives. Two future trends of space technology development include new space enterprises, and the national drive to achieve a more competitive global economic position.

Stone, Barbara A.↗
NASA NTRS1992

The future of management: The NASA paradigm

Prototypes of 21st century management, especially for large scale enterprises, may well be found within the aerospace industry. The space era inaugurated a number of projects of such scope and magnitude that another type of management had to be created to ensure successful achievement. The challenges will be not just in terms of technology and its management, but also human and cultural in dimension. Futurists, students of management, and those concerned with technological administration would do well to review the literature of emerging space management for its wider implications. NASA offers a paradigm, or demonstrated model, of future trends in the field of management at large. More research is needed on issues of leadership for Earth based project in space and space based programs with managers there. It is needed to realize that large scale technical enterprises, such as are undertaken in space, require a new form of management. NASA and other responsible agencies are urged to study excellence in space macromanagement, including the necessary multidisciplinary skills. Two recommended targets are the application of general living systems theory and macromanagement concepts for space stations in the 1990s.

Harris, Philip R.↗