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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Sweating responses during heat acclimation and moderate conditioning

Experiments were conducted on ten young male subjects to determine sweating onset, distribution, and patterns as well as the relationships of these responses to body temperature during heat acclimation and moderate conditioning performed in temperate (24 C) conditions. The subjects are randomly assigned to two groups of five subjects each. The experimental period consisted of eight successive days of either graded exercise to exhaustion on a bicycle ergometer in heat (acclimation group) or in a temperate environment (control group). Major conclusions are that (1) acclimation and conditioning result in relatively more sweat rate on the limbs than on the torso, but that these changes are less related to body temperature than torso sweat rate; and (2) sweating sensitivity increases during acclimation and conditioning, but its contribution to heat acclimation is minor.

Shvartz, E.↗
NASA NTRS1982

Surface-Contamination Inspection Tool for Field Use

Inspection tool detects surface contamination by measuring photoelectron emission. No vacuum chamber or controlled environment is used. Photoemission is measured under ordinary atmospheric conditions, so surfaces may easily be inspected in factories or in the field.

Smith, T.↗
NASA NTRS1981

Toward a theory of distributed word expert natural language parsing

An approach to natural language meaning-based parsing in which the unit of linguistic knowledge is the word rather than the rewrite rule is described. In the word expert parser, knowledge about language is distributed across a population of procedural experts, each representing a word of the language, and each an expert at diagnosing that word's intended usage in context. The parser is structured around a coroutine control environment in which the generator-like word experts ask questions and exchange information in coming to collective agreement on sentence meaning. The word expert theory is advanced as a better cognitive model of human language expertise than the traditional rule-based approach. The technical discussion is organized around examples taken from the prototype LISP system which implements parts of the theory.

Rieger, C.↗
NASA NTRS1981

A study of the effects of long-term exposure to fuels and fluids on the behavior of advanced composite materials

The periodic testing and evaluation of graphite/epoxy and Kevlar/epoxy material systems after subjecting test specimens to prolonged exposure to several laboratory-controlled environments deemed typical of normal aircraft operations is discussed. It is noted that specimen immersion in water or water-based fluids resulted in the greatest effect on the mechanical properties tested. Also, the environmental fluids showed a tendency to affect Kevlar/epoxy systems at an earlier exposure period than the graphite/epoxy systems. Results also indicate mechanical property strength retention generally being lower for the Kevlar/epoxy systems when compared to the corresponding graphite/epoxy systems in similar environments, after prolonged exposure.

Tanimoto, E. Y.↗
NASA NTRS1982

Field operations with cesium clocks in HF navigation systems

Networks of HF phase comparison marine navigation stations employing cesium clocks are discussed. The largest permanent network is in the Gulf of Mexico where some fourteen base stations are continuously active and others are activated as needed. These HF phase comparison systems, which operate on a single transmission path, require a clock on the mobile unit as well. Inventory consists of upwards of 70 clocks from two different manufacturers. The maintenance of this network as an operating system requires a coordinated effort involving clock preparation, clock environment control, station performance monitoring and field service.

Christy, E. H.↗
NASA NTRS1981

Meteorological lidar developments

A research program on remote optical measurements of humidity and temperature is summarized, and new results are given of such measurements as well as new data on the near IR absorption spectrum of H2O. The basic atmospheric technique is differential absorption lidar (DIAL) using narrow band, tunable dye lasers. Approximate wavelengths are 720, 820, 940 nm (H2O) and 690, 760 nm (O2; temperature). The requisite absorption line strengths and widths are measured in a controlled environment by means of grating spectroscopy and tunable lasers. Prospects for routine lidar meteorology, even from airplane and satellite platforms, appear excellent in several important applications; the conditions and the optical properties of the atmosphere can be obtained remotely by these means.

Wilkerson, T. D.↗
NASA NTRS1984

Electronically-Scanned Pressure Sensors

Sensors not pneumatically switched. Electronic pressure-transducer scanning system constructed in modular form. Pressure transducer modules and analog to digital converter module small enough to fit within cavities of average-sized wind-tunnel models. All switching done electronically. Temperature controlled environment maintained within sensor modules so accuracy maintained while ambient temperature varies.

Coe, C. F.↗
NASA NTRS1984

Flame-Test Chamber

Experimental chamber provides controlled environment for observation and measurement of flames propagating in expanding plume of flammable air/fuel mixture under atmospheric conditions. Designed to evaluate quenching capability of screen-type flame arresters in atmospheric vents of fuel cargo tanks aboard marine cargo vessels.

Bjorklund, R. A.↗
NASA NTRS1982

Current Concepts of the CELSS Program

The intent of the National Aeronautics and Space Administration in supporting the Controlled Environment Life Support System (CELSS) program is to establish the technological basis for the development of life support systems that are relatively independent of resupply. Such systems, it is anticipated, will be needed in the future to support manned space flight involving long duration missions and large numbers of people. The establishment of a resupply-independent life support system requires that all or most of the material in such a system be retained and recycled. In fact, leakage of gases into space, or into atmospheres of significantly lower pressure than that found inside of the system, is inevitable. Technical advances in sealing capabilities may reduce losses in the future, but no seals will ever be perfectly impervious to common atmospheric gases. Thus, a CELSS is envisioned to be a recycling system that will need to be resupplied with gases from time to time.

Macelroy, R. D.↗
NASA NTRS1982

Spacelab ground processing

During the Kennedy Space Center ground processing of Spacelab systems, emphasis is placed on verification of physical and functional interfaces aboard the spacecraft. Experiment-related operations consist of the integration of various experiment elements into the flight module. After Spacelab-Space Shuttle interfaces have been verified, the Spacelab cargo is transferred to the Orbiter Processing Facility in a controlled environment. Attention is given to the integrity of all payload-to-Space Shuttle interfaces during final closeout operations. Payload-related activities are minimal at the launch pad stage, since only limited access to the payload module is available through the Space lab Transfer Tunnel.

Scully, E. J.↗
NASA NTRS1983

Flight management systems - What are they and why are they being developed?

This paper presents the motivation for developing and using flight management systems. The architecture and theoretical basis of these systems is presented and their typical operation during a flight is described. Two computer programs developed to support flight management research are used to obtain numerical results which illustrate significant potential reductions in fuel used and/or airline operating costs which can be achieved through use of flight management systems. The specific levels of savings depend on the nature of the air traffic control system in which the aircraft operates. Accordingly, results are presented both for operations in the existing air traffic control system and in an air traffic control environment with reduced restrictions on airplane operations. The capability of airplanes equipped with suitable flight management systems to operate in a time-based (4-D) environment is also discussed. Programs of the Federal Aviation Administration which may influence the operation of flight management system equipped aircraft in the evolving National Airspace System are also briefly reviewed.

Creedon, J. F.↗
NASA NTRS1983

Polymers in solar energy utilization

A laser photoacoustic technique (LPAT) has been verified for performing accelerated life testing of outdoor photooxidation of polymeric materials used in solar energy applications. Samples of the material under test are placed in a chamber with a sensitive microphone, then exposed to chopped laser radiation. The sample absorbs the light and converts it to heat by a nonradiative deexcitation process, thereby reducing pressure fluctuations within the cell. The acoustic signal detected by the microphone is directly proportional to the amount of light absorbed by the specimen. Tests were performed with samples of ethylene/methylacrylate copolymer (EMA) reprecipitated from hot cyclohexane, compressed, and molded into thin (25-50 microns) films. The films were exposed outdoors and sampled by LPAT weekly. The linearity of the light absorbed with respect to the acoustic signal was verified.Correlations were established between the photoacoustic behavior of the materials aged outdoors and the same kinds of samples cooled and heated in a controlled environment reactor. The reactor tests were validated for predicting outdoor exosures up to 55 days.

Liang, R. H.↗
NASA NTRS1984

JT15D simulated flight data evaluation

The noise characteristics of the JT15D turbofan engine was analyzed with the objectives of: (1) assessing the state-of-art ability to simulate flight acoustic data using test results acquired in wind tunnel and outdoor (turbulence controlled) environments; and (2) predicting the farfield noise directivity of the blade passage frequency (BPF) tonal components using results from rotor blade mounted dynamic pressure instrumentation. Engine rotor tip speeds at subsonic, transonic, and supersonic conditions were evaluated. The ability to simulate flight results was generally within 2-3 dB for both outdoor and wind tunnel acoustic results. Some differences did occur in the broadband noise level and in the multiple-pure-tone harmonics at supersonic tip speeds. The prediction of blade passage frequency tone directivity from dynamic pressure measurements was accomplished for the three tip speed conditions. Predictions were made of the random and periodic components of the tone directivity. The technique for estimating the random tone component used hot wire data to establish a correlation between dynamic pressure and turbulence intensity. This prediction overestimated the tone level by typically 10 dB with the greatest overestimates occurring at supersonic conditions.

Holm, R. G.↗
NASA NTRS1982

Human factors dimensions in the evolution of increasingly automated control rooms for near-earth satellites

The NASA-Goddard Space Flight Center is responsible for the control and ground support for all of NASA's unmanned near-earth satellites. Traditionally, each satellite had its own dedicated mission operations room. In the mid-seventies, an integration of some of these dedicated facilities was begun with the primary objective to reduce costs. In this connection, the Multi-Satellite Operations Control Center (MSOCC) was designed. MSOCC represents currently a labor intensive operation. Recently, Goddard has become increasingly aware of human factors and human-machine interface issues. A summary is provided of some of the attempts to apply human factors considerations in the design of command and control environments. Current and future activities with respect to human factors and systems design are discussed, giving attention to the allocation of tasks between human and computer, and the interface for the human-computer dialogue.

Mitchell, C. M.↗
NASA NTRS1983

The development of a Space Shuttle General Purpose Work Station (GPWS)

The GPWS being developed for the Life Sciences Laboratory to be flown on the fourth Spacelab mission in late 1985 is characterized, and results from Phase I and Phase II tests are reported. The GPWS is designed to provide biological protection for both experiment and operator, a clean-room environment, control of liquids at zero gravity, protection against Spacelab-cabin contamination by chemical vapors, and work space with lights and other accommodations for one or two users in the zero-gravity neutral-body position. The flight hardware subsystems are examined and illustrated; the approach taken to evaluate human factors, performance, contaminant control, and user accommodation is explained; the design-verification unit for ground testing is described; and the improvements introduced in constructing the flight version are indicated.

Wagner, P. A.↗
NASA NTRS1984

A comparison of lightning and nuclear electromagnetic pulse response of tactical shelters

The internal response (electromagnetic fields and cable responses) of tactical shelters is addressed. Tactical shelters are usually well-shielded systems. Apart from penetrations by signal and power lines, the main leakage paths to the interior are via seams and the environment control unit (ECU) honeycomb filter. The time domain in three-dimensional finite-difference technique is employed to determine the external and internal coupling to a shelter excited by nuclear electromagnetic pulses (NEMP) and attached lightning. The responses of interest are the internal electromagnetic fields and the voltage, current, power, and energy coupled to internal cables. Leakage through the seams and ECU filter is accomplished by their transfer impedances which relate internal electric fields to external current densities. Transfer impedances which were experimentally measured are used in the analysis. The internal numerical results are favorably compared to actual shelter test data under simulated NEMP illumination.

Perala, R. A.↗
NASA NTRS1985

Mechanical Stress Regulation of Plant Growth and Development

Growth dynamics analysis was used to determine to what extent the seismic stress induced reduction in photosynthetic productivity in shaken soybeans was due to less photosynthetic surface, and to what extent to lower efficiency of assimulation. Seismic stress reduces shoot transpiration rate 17% and 15% during the first and second 45 minute periods following a given treatment. Shaken plants also had a 36% greater leaf water potential 30 minutes after treatment. Continuous measurement of whole plant photosynthetic rate shows that a decline in CO2 fixation began within seconds after the onset of shaking treatment and continued to decline to 16% less than that of controls 20 minutes after shaking, after which gradual recovery of photosynthesis begins. Photosynthetic assimilation recovered completely before the next treatment 5 hours later. The transitory decrease in photosynthetic rate was due entirely to a two fold increase in stomatal resistance to CO2 by the abaxial leaf surface. Mesophyll resistance was not significantly affected by periodic seismic treatment. Temporary stomatal aperture reduction and decreased CO2 fixation are responsible for the lower dry weight of seismic stressed plants growing in a controlled environment.

Mitchell, C. A.↗
NASA NTRS1985

CU in space: The University of Colorado get away special payload G-285

The University of Colorado's first Get Away Special was conceived by a dozen science and engineering students in the spring of 1984. Since that time, the project has grown to include over 100 undergraduate and graduate students who have 'provided the experimental objectives, design, construction, integration, testing and management of the payload. Faculty and staff of the university and its affiliated laboratories as well as engineers from local industries have provided many useful suggestions at all stages of development. The principal motivation for developing this payload is to provide university students with the opportunity to participate in space science and engineering beginning at the ground level. At the same time, they are contributing their results from new science and technological discoveries to several disciplines. There are four separate experiments integrated into the /'single payload of G-285 which are supported by internal payload !power, thermal environment control, command land data handling [ facilities and structural subsystems. The four experiments contained in this payload are: a single spectrometer performing i two experiments- one to study night time shuttle glow phenomena in the ultraviolet and the other to observe NO2 concentrations over / equatorial latitudes in the day; a fluids management experiment ' using centrifugation for particle/liquid/vapor separation; and an experiment using Phycomyces fungi to study the gravireceptor mechanism theory. The experiments are supported by a microprocessor, data storage devices, power and thermal control subsystems. All these are located within a sealed aluminum container. The container, a refitted sounding rocket casing, has a top and bottom which bolt to the main body of the rocket section. The top section holds a five inch diameter quartz window through which light enters the spectrometer. A rotating mirror assembly and one of two battery boxes are mounted on the outside of the top section below the interface plane of the MDA. A second battery box is attached to the bottom section of the sealed container. All payload items except the battery boxes and mirror assembly are located inside the sealed rocket section to insure containment and to prevent outgassing of materials. The container will be sealed prior to launch and purged with one atmosphere of argon.

Kent Tobiska↗