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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Hydrocarbon concentrations in fire toxicity tests as an indication of flash fire propensity

The concentrations of hydrocarbons in the gases from fire toxicity tests are often determined to obtain an indication of their contribution to toxic effects and of the mechanisms of thermal decomposition. Because the gas compositions produced in the University of San Francisco/NASA toxicity screening test are generated under identical pyrolysis conditions, they offer the potential of comparing the flash-fire propensity of various materials.

Hilado, C. J.↗
NASA NTRS1976

Pyroxene-spinel intergrowths in lunar and terrestrial pyroxenes

The paper describes the oriented intergrowth of spinel and pyroxene in a pigeonite from Luna 20, an augite from Apollo 16 anorthosite 67075, and an orthopyroxene from a spinel lherzolite nodule from the San Quintin volcanic field, Mexico. Using Mo K alpha radiation, photographs were taken of small, hand-picked single-crystals. A mechanism of exsolution is suggested in which the oxygen framework remains intact and spinel nuclei are formed by the migration of cations from interstitial sites and tetrahedral sites in the original non-stoichiometric pyroxene.

Okamura, F. P.↗
NASA NTRS1977

Some possible reference materials for fire toxicity tests

Suitable reference materials need to be selected in order to standardize any test method. The evaluation of cotton, polyethylene, polyether sulfone, polycarbonate, polystyrene, and polyurethane flexible and rigid foams as possible reference materials for the University of San Francisco/NASA toxicity screening test method is discussed.

Hilado, C. J.↗
NASA NTRS1977

Studies with the USF/NASA toxicity screening test method - Exercise wheels and oxygen replenishment

Continuing efforts to improve the University of San Francisco/NASA toxicity screening test method have included the addition of exercise wheels to provide a different measure of incapacitation, and oxygen replenishment to offset any effect of oxygen depletion by the test animals. The addition of exercise wheels limited the number of animals in each test and doubled the required number of tests without any significant improvement in reproducibility. Oxygen replenishment appears to have an effect on survival in the last 5 minutes of the 30-minute test, but the effect is expected to be similar for most materials.

Hilado, C. J.↗
NASA NTRS1977

A global thermospheric model based on mass spectrometer and incoherent scatter data MSIS. I - N2 density and temperature

Measurements of neutral nitrogen density from mass spectrometers on five satellites (AE-B, Ogo 6, San Marco 3, Aeros A, and AE-C) and neutral temperatures inferred from incoherent scatter measurements at four ground stations are combined to produce a model of thermospheric neutral temperatures and nitrogen densities similar to the Ogo 6 empirical model (Hedin et al., 1974). This global model is designated MSIS (mass spectrometer and incoherent scatter). The global average temperature, the annual temperature variation, lower bound density, and lower bound temperature are discussed. The data set covers the time period from the end of 1965 to mid-1975 and also a wide range of solar activities. Diurnal and semidiurnal variations in lower bound density and temperature are considered, as is magnetic activity.

Hedin, A. E.↗
NASA NTRS1977

A global thermospheric model based on mass spectrometer and incoherent scatter data MSIS. II - Composition

Measurements of O, He, and Ar from neutral gas mass spectrometers on four satellites (Ogo 6, San Marco 3, Aeros A, and AEC-C) and inferred oxygen and hydrogen densities from an ion mass spectrometer on AE-C have been combined with a neutral temperature and nitrogen density model to produce a global model of thermospheric composition in terms of inferred variations at 120 km. The data set covers the time period from mid-1969 to mid-1975. The MSIS (mass spectrometer and incoherent scatter data) model is compared with the Ogo 6 model (Hedin et al., 1974). Ar variations at 120 km tend to be in phase with temperature variations and inverse to the He, O, and H variations.

Hedin, A. E.↗
NASA NTRS1977

Active and inactive faults in southern California viewed from Skylab

A number of prominent linears in basement terrane of the Peninsular Ranges appeared on Skylab images. In most cases, they were represented by straight or gently curved valleys; however, detailed field investigations have shown that several of these linears mark previously unmapped faults which form two distinct fault sets; one set trends northeast, the other west-northwest. No indications of recent movement were present on these faults which were truncated by seismically active, northwest trending fault zones such as the Elsinore and San Jacinto. Right-lateral separation is demonstrable on the northeast trending set.

Merifield, P. M.↗
NASA NTRS1978

A proposed test area for the spaceborne geodynamic ranging system

Precise geodetic measurements are proposed in which an orbiting laser obtains intersite distance between retroreflectors 25 to 100 km apart on the ground. The recommended area is a rectangle 200 by 400 km in southern California and adjacent Nevada, trending northeast. It includes the entire width of the San Andreas fault zone, the Garlock fault, the thrust faults of the Transverse Ranges, and the active strike-slip faults of the Mojave Desert.

Lowman, P. D., Jr.↗
NASA NTRS1978

Executive summary: Benefit-cost evaluation of an intra-regional air service in the Bay Area and a technology assessment of transportation system investments

The benefits and costs that would result from an intra-regional air service operation in the San Francisco Bay area were determined by utilizing an iterative statistical decision model to evaluate combinations of commuter airport sites and surface transportation facilities in conjunction with service by a given commuter aircraft type in light of area regional growth alternatives and peak and off-peak regional travel patterns. The model evaluates such transportation option with respect to criteria of airline profitability, public acceptance, and public and private non-user costs. In so doing, it incorporates information on modal split, peak and off-peak use of the air commuter fleet, terminal and airport costs, development costs and uses of land in proximity to the airport sites, regional population shifts, and induced zonal shifts in travel demand. The model is multimodal in its analytic capability, and performs exhaustive sensitivity analysis.

Haefner, L. E.↗
NASA NTRS1978

Requirements for regional short-haul air service and the definition of a flight program to determine neighborhood reactions to small transport aircraft

An evaluation of the current status and future requirements of an intraregional short haul air service is given. A brief definition of the different types of short haul air service is given. This is followed by a historical review of previous attempts to develop short haul air service in high density urban areas and an assessment of the current status. The requirements for intraregional air service, the need for economic and environmental viability and the need for a flight research program are defined. A detailed outline of a research program that would determine urban community reaction to frequent operations of small transport aircraft is also given. Both the operation of such an experiment in a specific region (San Francisco Bay area) and the necessary design modifications of an existing fixed wing aircraft which could be used in the experiment are established. An estimate is made of overall program costs.

Feher, K.↗
NASA NTRS1978

Reproducibility of toxicity test data as a function of mouse strain, animal lot, and operator

The toxicity screening test method developed at the University of San Francisco was evaluated for reproducibility. The variables addressed were strain of mouse, lot of animals, and operator. There was a significant difference in response between Swiss Webster mice and ICR mice, with the latter exhibiting greater resistance. These two strains of mice are not interchangeable in this procedure. Variation between individual animals was significant and unavoidable. In view of this variation, between-lot and between-operator variations appear to have no practical significance. The significant variation between individual animals stresses the need for average values based on at least four animals, and preferably values based on at least two experiments and eight animals. Efforts to compare materials should be based on the evaluation of relatively simple responses using substantial numbers of animals, rather than on elaborate evaluation of single animals

Hilado, C. J.↗
NASA NTRS1978

Low-energy plasma observations at synchronous orbit

The University of California at San Diego Auroral Particles Experiment on the ATS 6 satellite in synchronous orbit has detected a low-energy plasma population which is separate and distinct from both the ring current and the plasma sheet populations. The density and temperature of this low-energy population are highly variable, with temperatures in the range kT = 1-30 eV and densities ranging from less than 1 per cu cm to more than 10 per cu cm. The occurrence of a dense low-energy plasma is most likely in the afternoon and dusk local time sectors, whereas n greater than 1 per cu cm is seen in the local night sector only during magnetically quiet periods. These observations suggest that this plasma is the outer zone of the plasmasphere. During magnetically active periods this low-energy plasma is often observed flowing sunward. In the dusk sector, strong sunward plasma flow is often observed for 1-2 hours prior to the onset of a substorm-associated particle injection.

Lennartsson, W.↗
NASA NTRS1978

Air terminals and liquid hydrogen commercial air transports

An initial appraisal is made of results of two studies of the ground requirements of liquid hydrogen (LH2) air transports. Each hypothesized the use of a 400-passenger 5500 nautical mile range subsonic commercial LH2 transport. Two of the world's busiest commercial airports, Chicago O'Hare International and San Francisco International, were selected for study. The current and predicted wide-body traffic at these airports was assumed to simulate the LH2 transport traffic at these airports in the 1990-1995 time period. Both studies produced conceptual designs for facilities to generate the required quantities of fuel from pipeline gaseous hydrogen and to deliver liquid hydrogen to the airplanes. Although the LH2 and jet fuel facilities were kept apart, both study teams found it practical to converge the fuel supply lines so that with proper safety and operational procedures and specialized LH2 equipment both LH2 and jet fuel transports can use common ramp and gate facilities.

Korycinski, P. F.↗
NASA NTRS1978

Toxicity of pyrolysis gases from some cellular polymers

Various samples of cellular polymers were evaluated for toxicity of pyrolysis gases, using the screening test method developed at the University of San Francisco. The cellular polymer samples included polyimide, polymethacrylimide, polybismaleimide, polyurethane, polyisocyanurate, polyethylene, polychloroprene, polyvinyl chloride, polystyrene, polysiloxane, and polyphosphazene. The cellular polymers exhibited varying levels of toxicity under these test conditions. Among the rigid cellular polymers, times to death were shortest with the imide type foams and longest with polyvinyl chloride and polystyrene. Among the flexible cellular polymers, times to death were shortest with polyimide and polyester, and longest with polychloroprene and polysiloxane. Increased char yield was not necessarily associated with reduced toxicity.

Hilado, C. J.↗
NASA NTRS1978

Concentration-response data on toxicity of pyrolysis gases from some natural and synthetic polymers

Concentration-response data are presented on the toxic effects of the pyrolysis gases from some natural and synthetic polymers, using the toxicity screening test method developed at the University of San Francisco. The pyrolysis gases from wool, red oak, Douglas fir, polycaprolactam, polyether sulfone, polyaryl sulfone, and polyphenylene sulfide appeared to exhibit the concentration-response relationships commonly encountered in toxicology. Carbon monoxide seemed to be an important toxicant in the pyrolysis gases from red oak, Douglas fir, and polycaprolactam, but did not appear to have been the principal toxicant in the pyrolysis gases from polyether sulfone and polyphenylene sulfide.

Hilado, C. J.↗
NASA NTRS1978

A high speed pointing system

A laser ranging system for use with the Space Shuttle, and applied to a precise determination of the distance between points arrayed on different tectonic plates, i.e., along the San Andreas fault, spaced at distances of 25, 50, and 100 km, is discussed with attention to the orbiting pointing system. The mount carrying the system contains a single elliptical mirror which directs ten laser firings per second (15-18 firings to each target), and receives the light reflected from the target. The mirror and all moving structural parts are constructed of Be. The axes are equipped with 19-bit shaft angle encoders and brushless torque motors. Care is taken to avoid structural resonances, and to ensure a minimum of servo settling time. A Kalman filter is used with the microprocessor system to interpolate low data rate commands to the higher data rates required by the pointing system.

Winston, G. C.↗
NASA NTRS1978

Detection of crustal motion using spaceborne laser ranging systems

Laser ranging systems operated from space are capable of detecting motions on earth in the 2-5 cm range. Attention is given to the detection of crustal motion, specifically along the San Andreas fault, and a mathematical model is presented for a geometric mode system consisting of at least five grid and three distant (fundamental) stations to be operated with airborne and spaceborne lasers. The ground stations are designed to operate unattended, and to work in conjunction with Shuttle-based hardware to become operational in 1982. The Shuttle laser ranging system is expected to provide survey data within a period from one to two weeks, with a resurvey capability to be used as required.

Kumar, M.↗
NASA NTRS1978

Ignitability of some insulation and building materials

A variety of insulation and building materials were evaluated for ignitability, using a screening test method developed at the University of San Francisco. Ignitability tended to be greater with the more efficient insulation materials because the insulating qualities resulted in a more rapid rise in temperature at the exposed surface. The use of a noncombustible facing material is recommended to provide protection from surface ignition.

Hilado, C. J.↗