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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 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

The spatial variability of coastal surface water temperature during upwelling

Thermal scanner imagery acquired during a field experiment designed to study an upwelling event in Lake Superior is investigated. Temperature data were measured by the thermal scanner, with a spatial resolution of 7 m. These data were correlated with temperatures measured from boats. One- and two-dimensional Fourier transforms of the data were calculated and temperature variances as a function of wavenumber were plotted. A k-to-the-minus-three dependence of the temperature variance on wavenumber was found in the wavenumber range of 1-25/km. At wavenumbers greater than 25/km, a k-to-the-minus-five-thirds dependence was found.

Scarpace, F. L.↗
NASA NTRS1979

Foil system fatigue load environments for commercial hydrofoil operation

The hydrofoil fatigue loads environment in the open sea is examined. The random nature of wave orbital velocities, periods and heights plus boat heading, speed and control system design are considered in the assessment of structural fatigue requirements. Major nonlinear load events such as hull slamming and foil unwetting are included in the fatigue environment. Full scale rough water load tests, field experience plus analytical loads work on the model 929 Jetfoil commercial hydrofoil are discussed. The problem of developing an overall sea environment for design is defined. State of the art analytical approaches are examined.

Graves, D. L.↗
NASA NTRS1980

Seasonal thermal energy storage in aquifers: Mathematical modeling studies in 1979

A numerical model of water and heat flow in geologic media was developed, verified, and tested. The hydraulic parameters (transmittivity and storativity) and the location of a linear hydrologic barrier were simulated and compared with results from field experiments involving two injection-storage-recovery cycles. For both cycles, the initial simulated and observed temperatures agree (55c).

Tsang, C. F.↗
NASA NTRS1980

The OMNIUM-G HTC-25 tracking concentrator

A point focusing, two axis tracking, high concentration ratio parabolic reflector is described. Field experience coupled with engineering improvements are shown to have manifested a design that is economic in the areas of manufacturing, packaging, delivering, installing, and commissioning the system into operation. The initial problems specifically with the OMNIUM-G model HTC-25 tracking concentrator are addressed.

Zelinger, S.↗
NASA NTRS1980

Joint microwave and infrared studies for soil moisture determination

The feasibility of using a combined microwave-thermal infrared system to determine soil moisture content is addressed. Of particular concern are bare soils. The theoretical basis for microwave emission from soils and the transport of heat and moisture in soils is presented. Also, a description is given of the results of two field experiments held during vernal months in the San Joaquin Valley of California.

Njoku, E. G.↗
NASA NTRS1980

Standing Alfven wave current system at Io: Voyager 1 observations

The enigmatic control of the occurrence frequency of Jupiter's decametric emissions by the satellite Io is explained theoretically on the basis of its strong electrodynamic interaction with the corotating Jovian magnetosphere leading to field aligned currents connecting Io with the Jovian ionosphere. Direct measurements of the perturbation magnetic fields due to this current system were obtained by the magnetic field experiment on Voyager 1 on 5 March 1979 when it passed within 20,500 km south of Io. An interpretation in the framework of Alfven waves radiated by Io leads to current estimates of 2.8 million amps. A mass density of 7400 to 13600 proton mass units per Cu cm is derived which compares very favorably with independent observations of the torus composition characterized by 7-9 proton mass units per electron for a local electron density of 1050 to 1500 per cu cm. The power dissipated in the current system may be important for heating the Io heavy ion torus, inner magnetosphere, Jovian ionosphere, and possibly the ionosphere or even the interior of Io.

Acuna, M. H.↗
NASA NTRS1980

Analysis of the charging of the SCATHA (P78-2) satellite

The charging of a large object in polar Earth orbit was investigated in order to obtain a preliminary indication of the response of the shuttle orbiter to such an environment. Two NASCAP (NASA Charging Analyzer Program) models of SCATHA (Satellite Charging at High Altitudes) were used in simulations of charging events. The properties of the satellite's constituent materials were compiled and representations of the experimentally observed plasma spectra were constructed. Actual charging events, as well as those using test environments, were simulated. Numerical models for the simulation of particle emitters and detectors were used to analyze the operation of these devices onboard SCATHA. The effect of highly charged surface regions on the charging conductivity within a photosheath was used to interpret results from the onboard electric field experiment. Shadowing calculations were carried out for the satellite and a table of effective illuminated areas was compiled.

Stannard, P. R.↗
NASA NTRS1981

Teaching/learning principles

The potential remote sensing user community is enormous, and the teaching and training tasks are even larger; however, some underlying principles may be synthesized and applied at all levels from elementary school children to sophisticated and knowledgeable adults. The basic rules applying to each of the six major elements of any training course and the underlying principle involved in each rule are summarized. The six identified major elements are: (1) field sites for problems and practice; (2) lectures and inside study; (3) learning materials and resources (the kit); (4) the field experience; (5) laboratory sessions; and (6) testing and evaluation.

Hankins, D. B.↗
NASA NTRS1981

NASA participation in the 1980 Persistent Elevated Pollution Episode/Northeast Regional Oxidant Study (PEPE/NROS) Project: Operational aspects

A field experiment designed to further understand the formation and transport of visibility reducing aerosols and to characterize regional scale air masses and urban plumes is described. Measurements were made primarily in the Ohio River Valley region. The NASA participation included obtaining measurements for the determination of mixing layer height and ozone profiles by using airborne remote sensor systems such as the ultraviolet differential absorption lidar, the high spectral resolution lidar, and the laser absorption spectrometer. Other NASA systems included the microwave atmospheric remote sensor, tethered balloons, an in situ measurements aircraft, and several photometer/transmissiometer systems.

Maddrea, G. L., Jr.↗
NASA NTRS1980

Precision of NO2 photolysis rate measurements

Gas-phase kinetic calculations indicate that actinometric measurements of the rate of solar photolysis of NO2 in nitrogen can be in error by +5 to -15% or more, unless odd oxygen N2O5 chemistry, and trace oxygen content are considered. A field experiment confirms that the effect of the quartz tube on the measured photolysis rate is less than 1.7%.

Dickerson, R. R.↗
NASA NTRS1981

Absolute tracer dye concentration using airborne laser-induced water Raman backscatter

The use of simultaneous airborne-laser-induced dye fluorescence and water Raman backscatter to measure the absolute concentration of an ocean-dispersed tracer dye is discussed. Theoretical considerations of the calculation of dye concentration by the numerical comparison of airborne laser-induced fluorescence spectra with laboratory spectra for known dye concentrations using the 3400/cm OH-stretch water Raman scatter as a calibration signal are presented which show that minimum errors are obtained and no data concerning water mass transmission properties are required when the laser wavelength is chosen to yield a Raman signal near the dye emission band. Results of field experiments conducted with an airborne conical scan lidar over a site in New York Bight into which rhodamine dye had been injected in a study of oil spill dispersion are then indicated which resulted in a contour map of dye concentrations, with a minimum detectable dye concentration of approximately 2 ppb by weight.

Hoge, F. E.↗
NASA NTRS1981

Long wavelength carbonyl sulfide photodissociation

The aeronomic implications of a preliminary observation of weak OCS photoabsorption above 270 nm are investigated. It is argued that the measured cross section is consistent with a forbidden transition in this wavelength region. Model calculations are made for the OCS photodissociation rates in daylight, the OCS and SO2 distributions in the upper atmosphere, and the budgets of sulfur in the stratosphere and OCS in the troposphere, assuming various extrapolations of the measured OCS absorption cross sections and quantum yields to longer wavelengths. It is shown that weak OCS absorption above 300 nm can have important consequences for all of these quantities. Laboratory and field experiments are identified which might lead to a better understanding of the atmospheric OCS cycle.

Turco, R. P.↗
NASA NTRS1981

Airborne simultaneous spectroscopic detection of laser-induced water Raman backscatter and fluorescence from chlorophyll a and other naturally occurring pigments

The airborne laser-induced spectral emission bands obtained simultaneously from water Raman backscatter and the fluorescence of chlorophyll and other naturally occurring waterborne pigments are reported here for the first time. The importance of this type data lies not only in its single-shot multispectral character but also in the application of the Raman line for correction or calibration of the spatial variation of the laser penetration depth without the need for in situ water attenuation measurements. The entire laser-induced fluorescence and Raman scatter emissions resulting from each separate 532-nm 10-nsec laser pulse are collected and spectrally dispersed in a diffraction grating spectrometer having forty photomultiplier tube detectors. Results from field experiments conducted in the North Sea and the Chesapeake Bay/Potomac River are presented. Difficulties involving the multispectral resolution of the induced emissions are addressed, and feasible solutions are suggested together with new instrument configurations and future research directions.

Hoge, F. E.↗
NASA NTRS1982

Measurement of losses of mesh membrane material for reflector applications with an S-band radiometer

The spatial resolution, the frequency of revisits, and the accuracy requirements for the detection of Earth surface parameters from space force the satellite designers to consider large space structures for microwaves. Some Earth surface parameters are only detectable with radiometers. Because the large reflectors should be much lighter than solid and deployable reflectors, mesh membrane material is considered to be used as the reflector. It is essential to determine the emissivity of the reflecting material even when close to zero to estimate the accuracy of the radiometer measurement. An existing S-band radiometer was used to determine the loss of a 1 sq m pretensioned mesh first in a field experiment and later in a well shielded laboratory set-up. The models for retrieving the emissivity of the mesh are described in detail and the equivalent losses for different mesh positions were calculated.

Blume, H. J. C.↗
NASA NTRS1982

Experimental evaluation of the Battelle accelerated test design for the solar array at Mead, Nebraska

A previously developed test design for accelerated aging of photovoltaic modules was experimentally evaluated. The studies included a review of relevant field experience, environmental chamber cycling of full size modules, and electrical and physical evaluation of the effects of accelerated aging during and after the tests. The test results indicated that thermally induced fatigue of the interconnects was the primary mode of module failure as measured by normalized power output. No chemical change in the silicone encapsulant was detectable after 360 test cycles.

Frickland, P. O.↗
NASA NTRS1981

Analysis of JP-4 fire test data and development of a simple fire model

A series of field experiments involving JP-4 fires of 7.6m dia and 15.2m dia was conducted under the sponsorship of NASA. The temperature inside the fire, the specie composition and vertical axial velocity were measured at several height locations and radial positions. The peak temperature recorded is 1400-1500 K; the velocities at 6m height are 11-12 m/s. The oxygen-to-nitrogen mass ratio along the vertical axis was found to be nearly a constant at 0.05. Significant necking of the fire was observed. A simple theoretical model was developed that predicts the experimental data on the velocity and vertical temperature distribution well. The model is based on the partial combustion of entrained air and assumed top-hat distributions for various property and flow parameters inside the fire. Quantitative agreement is obtained by using a value of 0.15 for the entrainment coefficient and 0.45 for the mixing efficiency factor. The model also predicts the fire necking.

Raj, P. K.↗
NASA NTRS1981

Standing Alfven wave current system at Io - Voyager 1 observations

The enigmatic control of the occurrence frequency of Jupiter's decametric emissions by the satellite Io has been explained theoretically on the basis of its strong electrodynamic interaction with the corotating Jovian magnetosphere leading to field-aligned currents connecting Io with the Jovian ionosphere. Direct measurements of the perturbation magnetic fields due to this current system were obtained by the Goddard Space Flight Center magnetic field experiment on Voyager 1 on March 5, 1979, when it passed within 20,500 km south of Io. An interpretation in the framework of Alfven waves radiated by Io leads to current estimates of 2.8 x 10 to the 6th A. A mass density of 7400-13,600 proton mass units/cu cm is derived, which compares very favorably with independent observations of the torus composition characterized by 7-9 proton mass units per electron for a local electron density of 1050-1500/cu cm. The power dissipated in the current system may be important for heating the Io heavy ion torus, inner magnetosphere, Jovian ionosphere, and possibly the ionosphere or even the interior of Io.

Acuna, M. H.↗
NASA NTRS1982

Ground-based lidar measurements of ozone, water vapor and aerosols in the lower stratosphere and troposphere

Lidar measurements of ozone and water vapor concentrations were performed during several field experiments in 1980-1981 by means of the differential absorption laser technique. Profiles up to 26 km for ozone and up to 9 km for water vapor are presented. Also, a lidar survey of aerosol layers ranging from 12 to 23 km were performed following the Mt. St. Helens major eruption (May 1980). Experiments were conducted at the CNRS lidar facility of the Haute Provence Observatory which is located in southern France (44 deg N, 5 deg E). For ozone a vertical profile is recorded in three sequences, each requiring 15 min of acquisition time. The relative accuracy is better than 5 percent at the lower altitude and falls to 20 percent at 25 km. For water vapor the time sequences are 4 min or 8 min long and the accuracy is better than 10 percent in the lower troposphere.

Flamant, P. H.↗