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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Long term evaluation of grease type lubricants in selected environments

The operating life of grease-type lubricants in various environments is evaluated. The test equipment and procedures are described. The lubricants were placed in the rolling element bearings of hysteresis synchronous motors and exposed to environments of a vacuum at 60 C, a vacuum at 93.3 C, 10 psia oxygen at 90 percent relative humidity at 60 C, 14.7 psia air at 90 percent relative humidity at 60 C, start-stop operation, and low temperature start capability for one or five years. The weights of the bearings were measured before and after lubrication; the weight data for each environment are analyzed. The data reveal that the high viscosity index perfluoroalkypolyether grease performs the best in a vacuum at moderate and high temperature, in low temperature start capability, and in start-stop steps; however, the grease does not work well in oxidizing and high relative humidity environments.

Dolan, F. J.↗
NASA NTRS1985

Calculation and use of an environment's characteristic software metric set

Since both cost/quality and production environments differ, this study presents an approach for customizing a characteristic set of software metrics to an environment. The approach is applied in the Software Engineering Laboratory (SEL), a NASA Goddard production environment, to 49 candidate process and product metrics of 652 modules from six (51,000 to 112,000 lines) projects. For this particular environment, the method yielded the characteristic metric set (source lines, fault correction effort per executable statement, design effort, code effort, number of I/O parameters, number of versions). The uses examined for a characteristic metric set include forecasting the effort for development, modification, and fault correction of modules based on historical data.

Basili, Victor R.↗
NASA NTRS1987

The PISCES 2 parallel programming environment

PISCES 2 is a programming environment for scientific and engineering computations on MIMD parallel computers. It is currently implemented on a flexible FLEX/32 at NASA Langley, a 20 processor machine with both shared and local memories. The environment provides an extended Fortran for applications programming, a configuration environment for setting up a run on the parallel machine, and a run-time environment for monitoring and controlling program execution. This paper describes the overall design of the system and its implementation on the FLEX/32. Emphasis is placed on several novel aspects of the design: the use of a carefully defined virtual machine, programmer control of the mapping of virtual machine to actual hardware, forces for medium-granularity parallelism, and windows for parallel distribution of data. Some preliminary measurements of storage use are included.

Pratt, Terrence W.↗
NASA NTRS1986

Scientific computing environment for the 1980s

An emerging scientific computing environment in which computers are used not only to solve large-scale models, but are also integrated into the daily activities of scientists and engineers, is discussed. The requirements of the scientific user in this environment are reviewed, and the hardware environment is described, including supercomputers, work stations, mass storage, and communications. Significant increases in memory capacity to keep pace with performance increases, the introduction of powerful graphics displays into the work station, and networking to integrate many computers are stressed. The emerging system software environment is considered, including the operating systems, communications software, and languages. New scientific user tools and utilities that will become available are described.

Bailey, F. R.↗
NASA NTRS1986

Assessment of space environment induced microdamage in toughened composite materials

The effects of simulated space environments on the microdamage in a series of commercially available toughened matrix composite systems was determined. Low-earth orbit (LEO) exposures were simulated by thermal cycling; geosynchronous orbit (GEO) exposures were simulated by electron irradiation plus thermal cycling. Material response was characterized by assessing the induced microcracking and its influence on chemical and mechanical property changes. All materials, including several advanced, tough thermoplastics microcracked when exposed to the simulated LEO environment except a 177 C cured single phase toughened epoxy composite. The GEO simulated environment produced microdamage in all materials. The results suggest that increased matrix toughness may not be the overriding factor leading to improved durability in the space environment.

Sykes, George F.↗
NASA NTRS1988

An intelligent processing environment for real-time simulation

The development of a highly efficient and thus truly intelligent processing environment for real-time general purpose simulation of continuous systems is described. Such an environment can be created by mapping the simulation process directly onto the University of Alamba's OPERA architecture. To facilitate this effort, the field of continuous simulation is explored, highlighting areas in which efficiency can be improved. Areas in which parallel processing can be applied are also identified, and several general OPERA type hardware configurations that support improved simulation are investigated. Three direct execution parallel processing environments are introduced, each of which greatly improves efficiency by exploiting distinct areas of the simulation process. These suggested environments are candidate architectures around which a highly intelligent real-time simulation configuration can be developed.

Carroll, Chester C.↗
NASA NTRS1988

Process migration in UNIX environments

To support process migration in UNIX environments, the main problem is how to encapsulate the location dependent features of the system in such a way that a host independent virtual environment is maintained by the migration handlers on the behalf of each migrated process. An object-oriented approach is used to describe the interaction between a process and its environment. More specifically, environmental objects were introduced in UNIX systems to carry out the user-environment interaction. The implementation of the migration handlers is based on both the state consistency criterion and the property consistency criterion.

Lu, Chin↗
NASA NTRS1988

The concurrent common Lisp development environment

A discussion of the Concurrent Common Lisp Development Environment on the iNTEL Personal Super Computer (iPSC) is presented. The advent of AI based engineering design tools has lead to a need for increased performance of computational facilities which support those tools. Gold Hill has approached this problem by directing its efforts to the creation of a concurrent, distributed AI development environment. This discussion focuses on the development tools aspect of the CCLISP environment. The future direction of Gold Hill in the area of distributed AI support environments is also presented.

Source record↗
NASA NTRS1988

Performance of multimirror quartzline lamps in a high-pressure, underwater environment

Multimirror Quartzline Lamps are extremely versatile and effective for nonconventional imaging requirements such as high-speed photo and video instrumentation and high-magnification imaging. The lamps' versatility though, is not limited to conventional environments. Many research experiments and projects require a high pressure environment. Continuous photographic data acquisition in a high-pressure vessel requires wall penetrations and creates design problems as well as potential failure sites. Underwater photography adds the extra consideration of a liquid. This report expands upon the basic research presented in, Performance of Multimirror Quartzline Lamps in High-Pressure Environments, (NASA-TM-83793, Ernie Walker and Howard Slater, 1984). The report provides information to professional industrial, scientific, and technical photographers as well as research personnel on the survivability of lighting a multimirror quartzline lamp in a nonconventional high-pressure underwater environment. Test results of lighted ELH 300 W multimirror quartzline lamps under high-pressure conditions are documented and general information on the lamps' intensity (footcandle output), cone of light coverage, approximate color temperature is provided. Continuous lighting considerations in liquids are also discussed.

Slater, Howard A.↗
NASA NTRS1989

Surface phenomena in plasma environments

Plasma interactions and their effects on materials depend on a number of factors, including the pre-existing environment, the properties of surface materials and the characteristics of the system. An additional dimension is the question of mission: some payloads may be much more sensitive to plasma interactions than others. As an example, a payload whose objective is to measure the ambient environment will be more sensitive to any effects than will a power system. Material specific effects include charging and its associated effects, which can result in short- and long-term damage. Selection of materials for a particular application requires consideration of all factors and assessment of effects due to all causes. Proper selection and suitability determination requires analysis to identify the actual environment combined with testing under exposure to single and combined environment factors.

Purvis, C. K.↗
NASA NTRS1988

Industrial applications of the microgravity environment

Opportunities for commercialization of the microgravity environment will depend upon the success of basic research projects performed in space. Significant demands for manufacturing opportunities are unlikely in the near term. The microgravity environment is to be considered primarily as a tool for research and secondarily as a manufacturing site. This research tool is unique, valuable, and presently available to U.S. investigators only through resources provided by NASA. The United States has an obligation to facilitate corporate research, maintain a flexible international policy, foster use of and assure access to a wide variety of facilities, and develop a posture of national and international leadership in and stewardship of research and materials processing in the microgravity environment. The National Research Council's Committee on Industrial Applications of the Microgravity Environment recommends six actions that strengthen this posture, including the formation of an authoritative organization to oversee the implementation of a program of microgravity research and its industrial applications.

Source record↗
NASA NTRS1988

The induced environment around Space Station

The potential impact of the International Space Station on its immediate environment is discussed, summarizing the results of recent investigations by NASA working groups. Consideration is given to the neutral-gas environment, induced photon emission, particulate contamination, the ionized environment, the Induced-environment Monitoring Package proposed for inclusion in the Space Station equipment, and recommendations for further research. Diagrams, drawings, graphs, and tables of numerical data are provided.

Torr, Marsha R.↗
NASA NTRS1988

An innovative approach to supplying an environment for the integration and test of the Space Station distributed avionics systems

This paper describes an innovative approach to supplying an environment for the integration and testing of the Space Station distributed avionics systems. The environment's relationship to the process flow of the Space Station verification from systems development to on-orbit verification is presented. This paper also describes the uses of the environment's hardware implementation called Data Management System (DMS) kits. The way in which this environment allows system developers to independently verify their system's performance, fault detection, and recovery capability is explained.

Barry, Thomas↗
NASA NTRS1988

The space radiation environment for electronics

The earth's space radiation environment is described in terms of charged particles as relevant to effects on spacecraft electronics. The nature and magnitude of the trapped and transiting environments are described in terms of spatial distribution and temporal variation. The internal radiation environment of the spacecraft is described in terms of shielding the high-energy particles of the free-field environment. Exposure levels are presented in terms of ionizing radiation dose and particle fluence for comparison to electronic component susceptibility.

Stassinopoulos, E. G.↗
NASA NTRS1988

Virtual interface environment workstations

A head-mounted, wide-angle, stereoscopic display system controlled by operator position, voice and gesture has been developed at NASA's Ames Research Center for use as a multipurpose interface environment. This Virtual Interface Environment Workstation (VIEW) system provides a multisensory, interactive display environment in which a user can virtually explore a 360-degree synthesized or remotely sensed environment and can viscerally interact with its components. Primary applications of the system are in telerobotics, management of large-scale integrated information systems, and human factors research. System configuration, research scenarios, and research directions are described.

Fisher, S. S.↗
NASA NTRS1989

Early Martian environments - The antarctic and other terrestrial analogs

The comparability of the early environments of Mars and earth, and the biological evolution which occurred on early earth, motivates serious consideration of the possibility of an early Martian biota. Environments which could have contained this early Martian life and which may presently contain evidence of this former life include aquatic, ice, soil, and rock habitats. Several analogs of these potential early Martian environments, which can provide useful information in searching for extinct life on Mars, are currently available for study on earth. These terrestrial analogs include the perennially ice-covered lakes and sandstone rocks in the polar deserts of Antarctica, surface of snowfields and glaciers, desert soils, geothermal springs, and deep subsurface environments.

Wharton, R. A., Jr.↗
NASA NTRS1989

SRB thermal environments

The objective was to utilize and expand the Solid Rocket Booster (SRB) orbital flight test data base for better predictions of future flight environments. There were five tasks associated with this effort: analyze the internal aft skirt wind tunnel data and incorporate it into a data base for generating design and preflight reeentry thermal environments; generate reentry design thermal environments for the SRB steel case with the nozzle extension off; generate reentry design thermal environments for the SRB Filament Wound Case with the nozzle extension off; develop an engineering tool to analyze the 3-D flowfield around the SRB aft skirt during reentry for the purpose of obtaining the frequency and severity of the belching gas intrusion internal to the aft skirt; and perform SRM transient joint flow analysis for subscale and full scale motor firing as well as determine the effects of debonds of the insulation on the fill time and heating within the field joint insulation. In addition, this work was extended to provide support for the 51L Shuttle SRB failure analysis.

Crain, W. K.↗
NASA NTRS1989

Real-time closed-loop simulation and upset evaluation of control systems in harsh electromagnetic environments

Digital control systems for applications such as aircraft avionics and multibody systems must maintain adequate control integrity in adverse as well as nominal operating conditions. For example, control systems for advanced aircraft, and especially those with relaxed static stability, will be critical to flight and will, therefore, have very high reliability specifications which must be met regardless of operating conditions. In addition, multibody systems such as robotic manipulators performing critical functions must have control systems capable of robust performance in any operating environment in order to complete the assigned task reliably. Severe operating conditions for electronic control systems can result from electromagnetic disturbances caused by lightning, high energy radio frequency (HERF) transmitters, and nuclear electromagnetic pulses (NEMP). For this reason, techniques must be developed to evaluate the integrity of the control system in adverse operating environments. The most difficult and illusive perturbations to computer-based control systems that can be caused by an electromagnetic environment (EME) are functional error modes that involve no component damage. These error modes are collectively known as upset, can occur simultaneously in all of the channels of a redundant control system, and are software dependent. Upset studies performed to date have not addressed the assessment of fault tolerant systems and do not involve the evaluation of a control system operating in a closed-loop with the plant. A methodology for performing a real-time simulation of the closed-loop dynamics of a fault tolerant control system with a simulated plant operating in an electromagnetically harsh environment is presented. In particular, considerations for performing upset tests on the controller are discussed. Some of these considerations are the generation and coupling of analog signals representative of electromagnetic disturbances to a control system under test, analog data acquisition, and digital data acquisition from fault tolerant systems. In addition, a case study of an upset test methodology for a fault tolerant electromagnetic aircraft engine control system is presented.

Belcastro, Celeste M.↗