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  • AERODYNAMICS  (69)
  • EARTH RESOURCES AND REMOTE SENSING  (43)
  • INSTRUMENTATION AND PHOTOGRAPHY  (40)
  • ENERGY PRODUCTION AND CONVERSION
  • 1985-1989  (166)
  • 1980-1984
  • 1975-1979
  • 1970-1974
  • 1987  (166)
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  • 1985-1989  (166)
  • 1980-1984
  • 1975-1979
  • 1970-1974
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  • 1
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    Characterizing forest stands with multi-incidence angle and multi-polarized SAR data (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The potential for using HH-polarized L-band SAR data obtained at different incidence angles from satellite altitudes to identify and map different forest cover types and stand density classes is studied. Reasonably accurate results are obtained if the speckle characteristics of the data are suppressed by low-pass spatial filters and a contextual classification algorithm. Multipolarized L-band SAR data obtained from aircraft altitudes over the same test site are also analyzed to assess the relationships between polarization and forest stand characteristics. It is found that incidence angle controls, to a very large extent, the characteristics of the data and the type of information that can be obtained from L-band, HH-polarized satellite SAR data. Cross-polarization of L-band SAR data enhances and differentiates various forest stand characteristics which cannot be defined using only the like-polarized data, and vice-versa.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Advances in Space Research (ISSN 0273-1177); 7; 11 1
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  • 2
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    Estimation of X-band scattering properties of tree components (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An X-band FM-CW very fine range resolution scatterometer was used to acquire backscattering data for a number of tree species. Using a model to describe the scattering source function and an experimental procedure for selected removal of plant parts allows the estimation of the volume backscatter coefficient and the volume extinction coefficient. It is found that: (1) leaves are strong attenuators as well as scatterers; (2) the albedo at a given angle of incidence is nearly independent of the tree type; (3) the tree limbs are good attenuators but rather poor scatterers; and (4) the albedo changes as a function of the angle of incidence and for deciduous trees is also a function of the season.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 3
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    Extraction of spectral hemispherical reflectance (albedo) of surfaces from nadir and directional reflectance data (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A radiative transfer model is used to investigate how the error of spectral hemispherical reflectance data obtained from nadir reflectance values varies with wavelength, solar zenith angle, leaf area index, and leaf orientation distribution. Several techniques employing multiple off-nadir view angles taken in azimuth planes are found to accurately infer spectral hemispherical reflectances, and to be well suited to sensor systems that scan in a known azimuth plane or view fore and aft in a known azimuth plane. The effects of errors in hemispherical reflectance on terrestrial energy budget and productivity calculations is also considered.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 8; 1727-174
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  • 4
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    A simple device for the preparation of embedded materials science specimens for ultramicrotomy (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A simple hand-held grinding fixture is discussed which can produce microtome mounts of hard materials, oriented interfaces, and powders embedded in a 5/16-in plastic rod. The device has been used for the ultramicrotomy of meteorite samples, 10-50 micron interplanetary dust particles, and thin films on plastic. Results are presented for a layer lattice silicate from the Murchison carbonaceous chondrite, illustrating the resolution and structural detail that can be obtained with the method.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Electron Microscopy Technique (ISSN 0741-0581); 6; 305
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  • 5
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    Perovskite oxides: Oxygen electrocatalysis and bulk structure (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-Lewis Research Center, Space Electrochemical Research and Technology (SERT); p 221-23
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  • 6
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    Simultaneous temperature and concentration measurement in front of solidifying monotectic systems using the two wavelength holographic technique (1987)
    In:  Other Sources
    Details
    Publication Date: 2013-08-29
    Description: A holographic technique for the simultaneous measurement of temperature and concentration in solidifying transparent model alloy systems was developed. Its application to the study of the interactions between the temperature, concentration, and fluid flow fields in such systems at 1 g and micro-g conditions is discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: ESA, Proceedings of the Sixth European Symposium on Material Sciences under Microgravity Conditions; p 309-311
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  • 7
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    Radiation damage of gallium arsenide production cells (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: High efficiency liquid phase epitaxy (LPE) gallium arsenide cells were irradiated with 1 Mev electrons up to fluences of 1 times 10 to the 16th power cm-2. Measurements of spectral response and dark and illuminated I-V data were made at each fluence and then, using computer codes, the experimental data was fitted to gallium arsenide cell models. In this way it was possible to determine the extent of the damage, and hence damage coefficients in both the emitter and base of the cell.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center, Space Photovoltaic Research and Technology 1986. High Efficiency, Space Environment and Array Technology; p 213-222
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  • 8
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    New dimension analyses with error analysis for quaking aspen and black spruce (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Dimension analysis for black spruce in wetland stands and trembling aspen are reported, including new approaches in error analysis. Biomass estimates for sacrificed trees have standard errors of 1 to 3%; standard errors for leaf areas are 10 to 20%. Bole biomass estimation accounts for most of the error for biomass, while estimation of branch characteristics and area/weight ratios accounts for the leaf area error. Error analysis provides insight for cost effective design of future analyses. Predictive equations for biomass and leaf area, with empirically derived estimators of prediction error, are given. Systematic prediction errors for small aspen trees and for leaf area of spruce from different site-types suggest a need for different predictive models within species. Predictive equations are compared with published equations; significant differences may be due to species responses to regional or site differences. Proportional contributions of component biomass in aspen change in ways related to tree size and stand development. Spruce maintains comparatively constant proportions with size, but shows changes corresponding to site. This suggests greater morphological plasticity of aspen and significance for spruce of nutrient conditions.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA-TM-89219 , NAS 1.15:89219
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  • 9
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    Noncontact temperature pattern measuring device (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This invention relates to a noncontact imagine pyrometer system for obtaining the true temperature image of a given substance in a contactless fashion without making assumptions about localized emissivity of the substance or the uniformity of the temperature distribution. Such a contactless temperature imaging system has particular application in the study and production of many materials where the physical contact required to make a conventional temperature measurement drastically effects or contaminates the physical process being observed. Two examples where accurate temperature profiles are of critical interest are: (1) the solid-liquid phase change interface in the production of electronic materials and (2) metastable materials in the undercooling region. The apparent novelty resides in the recognition that an active pyrometer system may be advantageously adapted to perform contactless temperature imaging so that an accurate temperature profile can be obtained.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NAS 1.71:NPO-17024-1-CU
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  • 10
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    Three-dimensional unsteady Euler solutions for propfans and counter-rotating propfans in transonic flow (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An Euler code designed for computing the unsteady, three-dimensional, transonic flow about single-rotating and counter-rotating propfans using dynamic blocked-grids is presented. The algorithm is a finite volume, flux-split, upwind, implicit scheme and solves the equations which have been written in a time-dependent curvilinear coordinate system. Relative motion of the blades for counter-rotating configurations is handled by requiring that grid lines be aligned after each discrete rotation of fore and aft rotor grid blocks. The method by which information is passed across block interfaces, as well as how downstream characteristic outflow boundary conditions which enforce simple radial equilibrium are implemented, is discussed. Comparisons of computed flow-field parameters and propfan performance with experimental data indicate good overall agreement between predictions and measurements.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 87-1197
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