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At least 1,495 records · Page 83
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

The natural resources inventory system ASVT project

The hardware/software and the associated procedures for a natural resource inventory and information system based on the use of LANDSAT-acquired multispectral scanner digital data is described. The system is designed to derive land cover/vegetation information from LANDSAT data and geographically reference this information for the production of various types of maps and for the compilation of acreage by land cover/vegetation category. The system also provides for data base building so that the LANDSAT-derived information can be related to information digitized from other sources (e.g., soils maps) in a geographic context in order to address specific applications. These applications include agricultural crop production estimation, erosion hazard-reforestation need assessment, whitetail deer habitat assessment, and site selection. The system is tested in demonstration areas located in the state of Mississippi, and the results of these application demonstrations are presented. A cost-efficiency comparison of producing land cover/vegetation maps and statistics with this system versus the use of small-scale aerial photography is made.

Joyce, A. T.↗
NASA NTRS1978

Fluxless Brazing and Heat Treatment of a Plate-Fin Sandwich Actively Cooled Panel

The processes and techniques used to fabricate plate-fin sandwich actively cooled panels are presented. The materials were 6061 aluminum alloy and brazing sheet having clad brazing alloy. The panels consisted of small scale specimens, fatigue specimens, and a large 0.61 m by 1.22 m test panel. All panels were fluxless brazed in retorts in heated platen presses while exerting external pressure to assure intimate contact of details. Distortion and damage normally associated with that heat treatment were minimized by heat treating without fixtures and solution quenching in an organic polymer solution. The test panel is the largest fluxless brazed and heat treated panel of its configuration known to exist.

Beuyukian, C. S.↗
NASA NTRS1979

Numerical simulation of VTPR temperature retrievals in a severe storm environment

Environmental conditions prior to convective development on the Great Plains of the U.S. on one case study day were investigated using the high-resolution infrared radiation sounder (HIRS) on Nimbus 6. A dual-retrieval scheme was developed to retrieve both lower tropospheric moisture and temperature parameters from the HIRS radiances. Total precipitable water, surface dew point temperatures, and stability indices were analyzed at a resolution of up to 30 Km on this day. Correlations with interpolated NES rawinsonde values were high and intrinsic noise levels were low. The true quality of the mesoscale analyses, however, is only seen by examining the small scale features at a scale of approximately 100 Km. Perturbations on the dry line feature for this day were seen in the satellite data, although the dry line position was just as easily picked up by surface observations. Convective development 2 1/2 hours later did seem to correlate well with the local maxima of moisture and instability seen in the satellite analyses.

Vonderhaar, T. H.↗
NASA NTRS1979

Contoured tank outlets for draining of cylindrical tanks in low-gravity environment

An analysis is presented for defining the outlet contour of a hemispherical-bottomed cylindrical tank that will prevent vapor ingestion when the tank is drained. The analysis was used to design two small-scale tanks that were fabricated and then tested in a low gravity environment. The draining performance of the tanks was compared with that for a tank with a conventional outlet having a constant circular cross-sectional area, under identical conditions. Even when drained at off-design conditions, the contoured tank had less liquid residuals at vapor ingestion than the conventional outlet tank. Effects of outflow rate, gravitational environment, and fluid properties on the outlet contour are discussed. Two potential applications of outlet contouring are also presented and discussed.

Symons, E. P.↗
NASA NTRS1977

Mass drivers. 2: Structural dynamics

Various structural and dynamical problems related to both small-scale forces between the drive coils and within the bucket structure as well as the overall combined large-scale dynamical interaction of the bucket stream and MDRE (Mass Drive Reaction Engine) structure are examined. The large-scale dynamics appear weakly stable. Finally, MDRE operation in an inverse-square-law gravitational field is discussed and the required curved shape of the guideway is computed.

William H. Arnold↗
NASA NTRS1978

The blue-to-green reflectance ratio and lake water quality

Correlations between the relative values of the blue and green reflectances of a lake and water quality indices, such as depth of photic zone, Secchi disk transparency, attenuation coefficient, and chlorophyll concentration, have been observed during an intensive satellite, aircraft, and surface vessel study of Lake Ontario and Conesus Lake. Determinations of blue and green reflectances from Skylab S190A color imagery are in excellent agreement with values obtained from small-scale color imagery from aircraft. Further, the accuracy of the satellite data appears within that required for extrapolation to the water quality indices. The study has also determined that changes in chlorophyll, lignin, and humic acid concentration can be discriminated by the behavior of the blue-to-green reflectance ratio and the reflectances of the green and red bands.

Piech, K. R.↗
NASA NTRS1978

Eddy diffusivities within Jupiter

The Flasar and Gierasch (1977) model for small-scale thermally driven turbulent convection in rapidly rotating systems is used to estimate eddy diffusivities within Jupiter's atmosphere and interior. It is assumed that heat transport is governed by a mixing-length law, that Jupiter's interior heat flow derives from thermal cooling, and that the entropy loss per nucleon is uniform throughout. A characteristic scalar diffusivity is obtained as a function of pressure level and latitude. The results show that the latitude variation in the diffusivity might be as large as a factor of 100 at 4600 bars. The consequences of such variations are considered.

Flasar, F. M.↗
NASA NTRS1978

The relationship between solar activity and coronal hole evolution

The relationship between coronal hole evolution and solar active regions during the Skylab period is examined. A tendency is found for holes to grow or remain stable when the activity nearby, seen as calcium plages and bright regions in X-rays, is predominantly large, long-lived regions. It is also found that there is a significantly higher number of small, short-lived active regions, as indicated by X-ray bright points, in the vicinity of decaying holes than there is near other holes. This is interpreted to mean that holes disappear at least in part because they become filled with many small scale, magnetically closed, X-ray emitting features. This interpretation, together with the observation that the number of X-ray bright points was much larger near solar minimum than it was during the Skylab period, provides a possible explanation for the disappearance of the large, near-equatorial coronal holes at the time of solar minimum.

Nolte, J. T.↗
NASA NTRS1979

Separation of core noise and jet noise

A method of identification and measurement of core noise and jet noise separately has been developed based on cross-correlation of signals from microphones located at widely separated angles in the far field of a jet. The different coherent properties of core noise and jet noise are used in this method to achieve this separation. Experimental data obtained in a small scale facility is analyzed to demonstrate that this method can be used successfully to separate the mean square pressures of core noise and jet noise.

Parthasarathy, S. P.↗
NASA NTRS1978

Mare Crisium area topography - A comparison of earth-based radar and Apollo mapping camera results

An earth-based radar topography (ERT) map has been constructed of the Mare Crisium area. Systematic and random sources of error are discussed. A comparison between the ERT map and Lunar Topographic Orthophotomaps shows a random mean discrepancy of less than 100 m between the two maps, except for small-scale (20 km or less in diameter) features, where systematic smoothing reduces the ERT elevation contrast

Zisk, S.↗
NASA NTRS1979

A review of earth-based radar mapping of the moon

Lunar radar mappings carried out in the late 1960s and 1970s have provided several valuable insights into lunar surface processes. These radar mappings used the delay-Doppler technique and needed the narrow antenna beams now available with large radio telescopes. Two-element radar interferometers have provided resolution of the delay-Doppler ambiguity at meter wavelengths and provided topographic information at centimeter wavelengths. These techniques have provided high resolution lunar radar maps at 3.8-cm, 70-cm, and 7.5-m wavelengths, a set of wavelengths which span the window available for earth-based radar mapping of the moon. These radar maps have been used along with other earth-based and Apollo orbital measurements to define surface units. The radar maps and these other data can describe physical properties such as small-scale blockiness and surface chemistry.

Thompson, T. W.↗
NASA NTRS1979

Evaluation of turbo-propulsion simulators as a testing technique for fighter aircraft

Ames Research Center has under way a program to develop the technology for using turbine-powered jet engine simulators as a test technique for simulating installed jet engine characteristics in small-scale wind-tunnel models of complete VSTOL fighter configurations. The program consists of three key elements: (1) static testing SN003 prototype turbine engine simulator (MAPS), (2) the development of the Propulsion Simulator Calibration Laboratory at Ames, and (3) the design, fabrication, and testing of a twin-engine 'closely coupled' V/STOL fighter wind-tunnel model. The model will use the Compact Multi-mission Propulsion Simulator (CMAPS) and will also be tested in flow-through and jet-effects modes to assess the effect of simultaneous inlet and nozzle flow simulation. This paper includes a description of the planned effort and anticipated future tasks.

Bailey, R. O.↗
NASA NTRS1978

Turbulent convection within rapidly rotating superadiabatic fluids with horizontal temperature gradients

A model is developed for small scale thermally driven turbulent convection in rapidly rotating systems. The Boussinesq equations of adiabatic and inviscid flow are perturbed about a basic state which is superadiabatic and which contains a horizontal temperature gradient balanced by a geostrophic wind. The growth rates and length scales of the most unstable modes are determined. It is found that these modes are either zonally or latitudinally symmetric, depending on the latitude and the horizontal temperature gradient. The transports of heat and momentum by the modes are computed. The linear amplitudes are assumed to be limited by shear instability. The model predicts a latitude dependent eddy diffusivity. The applicability of the model to astrophysical and planetary bodies is briefly discussed.

Flasar, F. M.↗
NASA NTRS1979

Jovian cloud structure and velocity fields

A global view of Jovian small-scale morphologies and zonal velocity profiles has been discussed previously. In the present paper, a regional comparison is made of the structures and velocity fields (meridional and zonal velocities) in the Jovian atmosphere as observed by Voyager I imaging system. The cloud structures discussed are fairly independent of the visual wavelength. The analysis shows that although both Jovian hemispheres exhibit similar patterns of diminishing and alternating eastward and westward jets as one progresses polewards, there is a pronounced asymmetry in the structural appearance of the two hemispheres.

Mitchell, J. L.↗
NASA NTRS1980

Low-cost LANDSAT processing system

LANDSAT analysis system is assembled from commercially available components at relatively low cost. Small-scale system is put together for price affordable for state agencies and universities. It processes LANDSAT data for subscene areas on repetitive basis. Amount of time required for processing decreases linearly with number of classifications desired. Computer programs written in FORTRAN IV are available for analyzing data.

Faust, N. L.↗
NASA NTRS1979

Low-altitude signatures of the boundary layers

Low altitude measurements reveal two distinct types of dayside boundary-layer plasmas. The first type is characterized by a proton distribution whose average energy decreases with increasing latitude and generally shows cool, unaccelerated electron fluxes. This type is observed only near noon and is correlated with southward interplanetary magnetic field (IMF). The second type is characterized by a 'V' signature in which the proton average energy first decreases then briefly increases as a function of latitude. The electron distribution in the latter case is hotter and often shows evidence of small scale acceleration regions. This type can be seen at all local times in the dayside and at noon is correlated with a northward IMF. It is suggested that the type 1 plasma is the low altitude signature of the plasma mantle and the type 2 plasma is the low altitude signature of the low latitude boundary layer.

Reiff, P. H.↗
NASA NTRS1979

Regenerative CO2 removal for PLSS application

Various concepts for the design of the nonelectrochemical absorber were defined and evaluated. A preliminary design based on the use of hollow fiber membranes was developed. Small scale bench testing demonstrated the carbon dioxide removal capability and provided design data for scale-up to the one person level. A full scale conceptual design of the absorbent regeneration hardware using six electrochemical cells was also completed. The design was supported by single cell testing and showed that a full scale regeneration system, operating continuously over 24 hours, can regenerate the absorbent from one extravehicular activity mission. The single cell regeneration hardware was operated for over 800 hours.

Heppner, D. B.↗
NASA NTRS1980

Surface measuring technique

Measurement of the surface contour of a large electrostatically formed concave reflector using a modified Foucault or knife edge test is described. The curve of the actual electrostatically formed reflector surface is compared to a curve representing a reference sphere. Measurements of surface slope and deviation are calculated every 15 cm along the reflector's horizontal and vertical diameters. Characterization of surface roughness on a small scale compared to the laser spot size at the reflector are obtained from the increased laser spot size at a distant projection screen.

Spiers, R. B., Jr.↗