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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

A Meteorological (humidity, temperature, aerosols)) mobile dial system: Concepts and design

Since 1982 a program was conducted to develop a mobile meteorological (humidity, temperature, aerosols) Differential Absorption Lidar (DIAL) devoted to the studies of the nuclear power plant atmospheric surroundings. The measurement objectives are defined according to the user needs and the lidar feasibility. The concepts and design adopted to meet both the requirement and the measurement objectives are described. Each sub-system is addressed sequentially: transmitting system, receiving system, detection system, and post detection.

Cahen, C.↗
NASA NTRS1986

Statistical relation between monthly mean precipitable water and surface-level humidity over global oceans

Monthly summaries of atmospheric soundings taken over 17 years from 49 midocean stations at small islands and weather ships distributed over major oceans are examined. Over tropical oceans, precipitable water is found to be a better predictor of surface-level humidity than surface-level air temperature. A statistical relation in the form of a polynomial is derived; from this relation, the monthly-mean, surface-level mixing ratio can be computed from monthly-mean precipitable water. The root-mean-square differences between the measured and derived values were found to be less than 8 x 10 to the -4th over most ocean areas. Such a relation is useful in deriving large-scale evaporation and latent heat flux data from the ocean, using spaceborne observations. The temporal and spatial variabilities of data deviations from this relation are examined. This relation is found to be applicable to all major ocean basins and can be used to monitor interannual variability. Boundary-layer thermodynamics of different air masses are suggested as an explanation of some characteristics of this relation.

Liu, W. T.↗
NASA NTRS1988

Temperature, Humidity, And Polymer Aging

Report presents analysis of experimental data on electrical resistivity of polymer (polyvinyl butyral) as function of temperature and relative humidity. Resulting theoretical expression for electrical resistivity resembles generally accepted empirical law for the corrosion rate.

Cuddihy, Edward F.↗
NASA NTRS1987

Development of a regenerable humidity and CO2 control system for an advanced EMU

A 5-h-regenerable nonventing humidity and CO2 control subsystem (HCCS) technology demonstration unit is being developed for potential use in an Advanced Extravehicular Mobility Unit for Space Station application. The HCCS incorporates a weak-base-anion exchange resin packed in a metal-foam-matrix heat exchanger. This system simultaneously removes CO2 and water vapor, with the resulting exothermic heat of reaction rejected to the heat exchanger. The system has no moving parts, resulting in a highly reliable simple configuration. Regeneration may be accomplished via internal heating and vacuum.

Nalette, Timothy A.↗
NASA NTRS1987

Deterioration of ZnO/SiO2 diode packages in high humidity

A case study is reported in which the ZnO/SiO2 glass used to package a power rectifier combined with the design to produce a catastropic corrosion failure of the system. Metallic Zn inclusions, present in the glass, played a critical role in creating a conductive path for corrosion currents. Actual equipment failure was the result of an open circuit trace created by corrosion. It is concluded that the presence of Zn inclusions in the glass of this type of package may result in long-term reliability problems for equipment used in high humidity environments.

Evans, John↗
NASA NTRS1988

Vibrational-vibrational coupling in air at low humidities

Calculations of sound absorption in air are traditionally based on the assumption that molecular relaxations in N2 and O2 are independent. In binary mixtures of these two gases, however, they are not independent; rather, molecular relaxation is known to be controlled by a very strong vibrational-vibrational (V-V) coupling, which influences both the relaxation frequencies and the relaxation strengths. This article shows that small concentrations of the air constituents CO2 and H2O, which themselves possess a strong V-V coupling to N2 and O2, serve to decouple the N2 and O2 relaxations. To characterize the N2-O2 coupling a coupling strength is derived which depends upon the constituent concentrations and the related reaction rate constants. It is found that the molecular relaxations associated with N2 and O2 in air experience a gradual transition from strong to weak coupling as the humidity increases beyond approximately 0.001 mole percent.

Zuckerwar, Allan J.↗
NASA NTRS1988

Development of an advanced solid amine humidity and CO2 control system for potential Space Station Extravehicular Activity application

A system for removing metabolic carbon dioxide and water vapor from breathing air within a space suit during NASA Space Station EVA is discussed. The solid amine compound used is packed within a water-cooled metal foam matrix heat-exchanger to remove the exothermic heat of chemical reaction. Details of the design of a canister for humidity and carbon dioxide control and performance of the system are presented.

Nalette, Timothy A.↗
NASA NTRS1988

On the prediction of the behavior of the velocity, temperature and humidity fields above a thermally stratified air-water interface

A turbulent kinetic energy-dissipation (k-epsilon) model is employed to numerically simulate the behavior of the mean velocity, temperature and humidity fields, along with such second-order statistics as Reynolds stresses, turbulent heat and mass transfer correlation, and bulk transfer coefficients in the boundary layer above wind-generated laboratory waves. The k and epsilon equations have been properly modified to account for thermal stratification, the presence of free surface, and favorable pressure gradient effects. Predictions are compared with available data.

Papadimitrakis, Yiannis A.↗
NASA NTRS1989

Investigation of humidity control via membrane separation for advanced Extravehicular Mobility Unit (EMU) application

This paper describes the development of a membrane-based process for dehumidifying the Extravehicular Mobility Unit (EMU). The membrane process promises to be smaller, lighter, and more energy efficient than the other technologies for dehumidification. The dehydration membranes were tested for 90 days at conditions expected to be present in the EMU. The results of these tests indicate that membrane-based technology can effectively control humidity in the EMU.

Newbold, D. D.↗
NASA NTRS1990

Wave number spectra from temperature-humidity infrared radiometer 6.7-micron water vapor data

Wave number spectra from Nimbus 7 temperature-humidity infrared radiometer 6.7-micron water vapor data are analyzed using series 4800 km long, in regions free of high clouds and frontal zones. In these regions, the brightness temperatures approximate temperatures on a water vapor isosteric (constant density) surface, rather than averages over a broad vertical layer. Power above the noise can be extracted down to wavelengths of about 60 km. Fitting the power spectrum versus horizontal wave number k to a k to the -nth power law for wavelengths from 60 to a few hundred kilometers gives slopes of n = 2.7 to 3.0, depending on the exact wave numbers that are fitted. Thunderstorms and convective cloud systems may constitute an energy source for the reverse energy cascade which produces a -5/3 spectral slope. The results suggest that when these features are not present, the enstrophy-cascading process that gives a -3 slope may govern the motion at scales smaller than it has heretofore been observed.

Manney, Gloria L.↗
NASA NTRS1990

The extent of the unstable Monin-Obukhov layer for temperature and humidity above complex hilly grassland

An analysis is given of radiosonde measurements of the potential temperature, specific humidity, and wind profiles under unstable windy conditions during the First International Satellite Land Surface Climatology Project Field Experiment in Kansas. It is found that about 86 percent of the profiles have a height range over which the Monin-Obukhov (1954) similarity is valid. It is shown that the Businger-Dyer version of the similarity functions (Businger, 1988) is satisfactory for analyzing radiosonde profiles.

Brutsaert, Wilfried↗
NASA NTRS1990

Humidity-induced room-temperature decomposition of Au contacted indium phosphide

It has been found that Au-contacted InP is chemically unstable at room temperature in a humid ambient due to the leaching action of indium nitrate islands that continually remove In from the contact metallization and thus, in effect, from the Inp substrate. While similar appearing islands form on Au-contacted GaAs, that system appears to be stable since leaching of the group III element does not take place.

Fatemi, Navid S.↗
NASA NTRS1989

Seasonal nitrous oxide flux from an intensively managed pasture in a humid subtropical ecosystem

Nitrous oxide (N2O) flux from vented chambers was measured over intensively and minimally managed bermuda grass hay meadows in a humid, subtropical ecosystem for several years during scheduled sampling protocol following harvest, fertilization and rainfall events while measuring diel N2O emissions once during each of 5 seasonal day growth cycles which divided each calendar year. Soil pools of nitrite NO2(-), nitrate NO3(-), and ammonia (NH3) were measured in soil samples taken at 2 and 10 cm depths during each emission collection to determine transformations of the nitrogen pools coupled with N2O emissions. The highest diel N2O emission occur midday in the Spring cycle, measuring 9.0 g N/ha/d only for several weeks, while emissions dropped to less than 1.0 g N/ha/day during hot, dry, and colder months. Intensively managed meadows (4 fertilizations and harvests per year plus pest management) induced higher seasonal N2O emissions than minimal treatment (1 fertilization and harvest) averaging 2.75 and 5.97 g N/ha/day. Nitrous oxide emission data as responses to soil parameters and environmental parameters were also measured where air temperature, soil moisture, and fertilization were the most powerful factors.

Brams, Eugene A.↗
NASA NTRS1991

Thermal and humidity winds in outer planet atmospheres

Among the dynamical consequences of molecular weight variations due to condensation in hydrogen atmospheres is the creation of geostrophic wind variations by horizontal variations in molecular weight. In the present illustrative model, it is shown that such horizontal gradients are generated by methane condensation in the cases of the Uranus and Neptune atmospheres. As a result, the zonal wind shear is different in both magnitude and direction from the value determined while neglecting molecular weight variations. The horizontal molecular weight gradients due to condensation of minor constituents also vertically shear the zonal wind, giving rise to what may be termed the 'humidity wind'.

Sun, Zi-Ping↗
NASA NTRS1991

Simulations of the effect of a warmer climate on atmospheric humidity

Increases in the concentration of water vapor constitute the single largest positive feedback in models of global climate warming caused by greenhouse gases. It has been suggested that sinking air in the regions surrounding deep cumulus clouds will dry the upper troposphere and eliminate or reverse the direction of water vapor feedback. This hypothesis has been tested by performing an idealized simulation of climate change with two different versions of a climate model which both incorporate drying due to subsidence of clear air but differ in their parameterization of moist convection and stratiform clouds. Despite increased drying of the upper troposphere by cumulus clouds, upper-level humidity increases in the warmer climate because of enhanced upward moisture transport by the general circulation and increased accumulation of water vapor and ice at cumulus cloud tops.

Del Genio, Anthony D.↗
NASA NTRS1992

Precipitable water and surface humidity over global oceans from special sensor microwave imager and European Center for Medium Range Weather Forecasts

Global fields of precipitable water W from the special sensor microwave imager were compared with those from the European Center for Medium Range Weather Forecasts (ECMWF) model. They agree over most ocean areas; both data sets capture the two annual cycles examined and the interannual anomalies during an ENSO episode. They show significant differences in the dry air masses over the eastern tropical-subtropical oceans, particularly in the Southern Hemisphere. In these regions, comparisons with radiosonde data indicate that overestimation by the ECMWF model accounts for a large part of the differences. As a check on the W differences, surface-level specific humidity Q derived from W, using a statistical relation, was compared with Q from the ECMWF model. The differences in Q were found to be consistent with the differences in W, indirectly validating the Q-W relation. In both W and Q, SSMI was able to discern clearly the equatorial extension of the tongues of dry air in the eastern tropical ocean, while both ECMWF and climatological fields have reduced spatial gradients and weaker intensity.

Liu, W. T.↗
NASA NTRS1993

Microwave soil moisture estimation in humid and semiarid watersheds

Land surface hydrologic-atmospheric interactions in humid and semi-arid watersheds were investigated. Active and passive microwave sensors were used to estimate the spatial and temporal distribution of soil moisture at the catchment scale in four areas. Results are presented and discussed. The eventual use of this information in the analysis and prediction of associated hydrologic processes is examined.

O'Neill, P. E.↗
NASA NTRS1994

Surface temperatures in the polar regions from Nimbus 7 temperature humidity infrared radiometer

Monthly surface temperatures in the Arctic and Antarctic regions have been derived from the 11.5 micrometer thermal infrared channel of the Nimbus 7 temperature humidity infrared radiometer (THIR) for a whole year in 1979 and for a winter and a summer month from 1980 through 1985. The data set shows interannual variability and provides spatial details that allow identification of temperature patterns over sea ice and ice sheet surfaces. For example, the coldest spot in the southern hemisphere is observed to be consistently in the Antarctic plateau in the southern hemisphere, while that in the northern hemisphere is usually located in Greenland, or one of three other general areas: Siberia, the central Arctic, or the Canadian Archipelago. Also, in the southern hemisphere, the amplitude of the seasonal fluctuation of ice sheet temperatures is about 3 times that of sea ice, while in the northern hemisphere, the corresponding fluctuations for the two surfaces are about the same. The main sources of error in the retrieval are cloud and other atmospheric effects. These were minimized by first choosing the highest radiance value from the set of measurements during the day taken within a 30 km by 30 km grid of each daily map. Then the difference of daily maps was taken and where the difference is greater than a certain threshold (which in this case is 12 C), the data element is deleted. Overall, the monthly maps derived from the resulting daily maps are spatially and temporally consistent, are coherent with the topograph y of the Antarctic continent and the location of the sea ice edge, and are in qualitative agreement with climatological data. Quantitatively, THIR data are in good agreement with Antarctic ice sheet surface air temperature station data with a correlation coefficient of 0.997 and a standard deviation of 2.0 C. The absolute values are not as good over the sea ice edges, but a comparison with Russian 2-m drift station temperatures shows very high correlation (with correlation coefficient at 0.998) and a standard deviation of 1.1 C. Overall, the rms error is estimated to be from 1 to 2 C, depending on the surface, while the average bias when compared with in situ data is less than 2 C.

Comiso, Josefino C.↗