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  • EARTH RESOURCES AND REMOTE SENSING  (643)
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  • 1
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    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 240-241
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  • 2
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 236-237
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  • 3
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 238-239
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  • 4
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 234-235
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  • 5
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 231
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  • 6
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 229-230
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  • 7
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 232-233
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  • 8
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 227-228
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  • 9
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 221-223
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  • 10
    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 148
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  • 11
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    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 130-131
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  • 12
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    Publication Date: 2011-08-19
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 16
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  • 13
    Publication Date: 2011-08-18
    Description: Experiments using ground-based measurements of canopy temperatures have shown that plant temperatures are good indicators of plant water stress, and thus are useful for assessing water requirements and predicting yields. An intensive 23-day airborne- and ground-measurement program was conducted in Phoenix, Arizona in 1977 to compare airborne-acquired wheat canopy temperatures with simultaneous ground measurements. For canopies that covered at least 85 percent of the soil surface, airborne measurements differed from ground measurements of plant temperature by less than 2 C. Regardless of the amount of plant cover, the airborne measurements were virtually identical to ground-nadir measurements, and thus represent a combination of plant temperature and solid background temperature.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Feb. 198
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  • 14
    Publication Date: 2011-08-18
    Description: The chemiluminescent rocket ozonesonde utilizing rhodamine-B as a detector and self-pumping for air sampling has been improved. The instrument employs standard meteorological sounding systems and is the only technique available for routine nighttime ozone measurements above balloon altitudes. The chemiluminescent detector, when properly calibrated, is shown to be specific to ozone, stable, and of sufficient sensitivity for accurate measurements of ozone from about 65-20 km. An error analysis indicates that the measured ozone profiles have an absolute accuracy of about + or - 12% and a precision of about + or - 6%. Approximately 20 flights have been conducted for geophysical investigations, while additional flights were conducted with other rocket and satellite ozone soundings for comparisons. In general, these comparisons showed good agreement.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 51; Oct. 198
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  • 15
    Publication Date: 2011-08-18
    Description: Potential industrial sites were assessed using high and medium altitude aircraft photographs and supporting information on the 4,730 sq. km. (1,825 sq. mile) county. Factors evaluated include land availability, slope, site accessibility, soil drainage, other subsurface characteristics, and the expected physical as well as visual impacts on existing land use. Areas unavailable or unsuitable for development were eliminated first, and the remaining areas evaluated and the best sites identified.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Cornell Univ. Remote Sensing Program; 138 p
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  • 16
    Publication Date: 2011-08-18
    Description: A zoom stereoscope was used to interpret aerial color photographs of the Finger Lakes region near Bath, New York, and areas of conifers were delineated on acetate sheets. Scale was determined for each photograph and units were converted to acres. Photographically enlarged positive transparencies of imagery from LANDSAT bands 5,6, and 7 for the southern portion of the study area were placed in a cold additive viewer and registered with each other to provide a composite image. A green filter was used on band 5, blue on band 6, and red on band 7. Conifers appeared at dark, reddish purple. Average was determined using a grid. Results show that the total confer stands within 50 miles of Bath is approximately 176,000 acres of which 60,000 acres are in Pennsylvania. The study was conducted to determine the feasibility of locating a particleboard manufacturing firm in the Southern Tier.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Cornell Univ. Remote Sensing Program; 3 p
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  • 17
    Publication Date: 2011-08-18
    Description: Manual photointerpretation techniques were used to analyze images acquired by high altitude aircraft, the Skylab multispectral and Earth terrain camera (ETC), the LANDSAT multispectral scanner, and the LANDSAT-3 return beam vidicon camera. A color-additive viewer, and digital image analysis were also used on the LANDSAT MSS imagery. The value of each type of remotely sensed data was judged by the ease and accuracy of clearcut identification, and by the amount of detail discernible, especially regarding revegetation. Results of a site study in the Allegheny National Forest, Pennsylvania indicate that high altitude aerial photography, especially color infrared photography acquired during the growing season, is well suited for identifying clearcuts and assessing revegetation. Although photographs acquired with Skylab's ETC also yielded good results, only incomplete inventories of clearcuts could be made using LANDSAT imagery. Results for the Adirondack region of New York State were similar for the aircraft and satellite photography, but even less satisfactory for the LANDSAT imagery.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Cornell Univ. Remote Sensing Program; 157 p
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  • 18
    Publication Date: 2011-08-17
    Description: A circular-scan streak tube designed for use in a laser ranging system is described. Electrostatic focusing is used between the photocathode and a microchannel plate, and electrons from the microchannel plate are proximity focused onto an output phosphor screen. Electron beam deflection is achieved by driving two orthogonal sets of deflection plate assemblies in phase quadrature at a frequency of 200 MHz. The light intensity in the output beam trace is measured by using a circular Reticon array of 720 photodiodes, which is fiber-optically coupled to the output phosphor screen of the tube. Sample measurements of frequency-doubled Nd:YAG laser-pulse waveforms are given. Also the output beamwidth has been measured at the 200-MHz deflection frequency. The results suggest a limiting resolution of 33 psec for the circular-scan streak tube used for these tests.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; Oct. 15
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  • 19
    Publication Date: 2011-08-17
    Description: The use of laser-induced water Raman backscatter for remote thin oil film detection and thickness measurement is reported here for the first time. A 337.1-nm nitrogen laser was used to excite the 3400-cm-1 OH stretch band of natural ocean water beneath the oil slick from an altitude of 150 m. The signal strength of the 381-nm water Raman backscatter was always observed to depress when the oil was encountered and then return to its original undepressed value after complete aircraft traversal of the floating slick. After removal of background and oil fluorescence contributions, the ratio of the depressed-to-undepressed airborne water Raman signal intensities, together with laboratory measured oil extinction coefficients, is used to calculate the oil film thickness.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; Oct. 1
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  • 20
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    Publication Date: 2011-08-17
    Description: Research, development, and application of atmospheric laser Doppler velocimetry are overviewed. Consideration is given to operation principles of CO2 heterodyne systems. Global wind, pollution, V/STOL flow, and true airspeed measurements are outlined. Wind energy, dust devils, water spouts, tornadoes, and aircraft wake vortices are covered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 19; July-Aug
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  • 21
    Publication Date: 2011-08-17
    Description: A pulsed infrared lidar system designed for application to the remote sensing of atmospheric trace gases from an airborne platform is described. The system is also capable of measuring the infrared backscatter characteristics of the ocean surface, terrain, cloud, and aerosol targets. The lidar employed is based on dual wavelength pulse energy measurements in the 9-11 micrometer wavelength region.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 19; July-Aug
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  • 22
    Publication Date: 2011-08-17
    Description: A simple device is described that is capable of providing real-time 3-D viewing of extended X-ray and gamma-ray objects. The visible-light images produced by the device are not merely stereoscopic, i.e., one perspective, but possess both horizontal and vertical parallax with a reasonably large field of view.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; Sept. 1
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  • 23
    Publication Date: 2011-08-17
    Description: Infrared grid polarizers consisting of copper lines with a 3.6-micron grid constant on a 4-micron-thick Mylar polyester substrate have been prepared by the techniques of photolithography and sputter-etching. Their polarization properties have been measured and found to be suitable for use at infrared frequencies below 700/cm. The polarizers have been used to extend the useful frequency range of a Martin-Puplett polarizing interferometer designed for Fourier transform spectroscopy. The efficiency of the interferometer has been measured over a frequency range from 50 to 700/cm and compared to that of a conventional Michelson interferometer. The results are shown to be consistent with the measured properties of the polarizers. Methods are suggested for improving the efficiency of a Martin-Puplett interferometer which employs these polarizers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Infrared Physics; 20; July 198
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  • 24
    Publication Date: 2011-08-17
    Description: The various stages in carrying out a monocluster block unsupervised classification using Landsat MSS data are described. Procedures for carrying out these various stages were found to be far from well-established for the type of terrain being investigated, which is rugged and contains many small land cover units. Two particular difficulties were encountered: first, that of precise ground location of pixels; and, secondly, that of objectively evaluating the results. Ways in which these can be surmounted are suggested.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 25
    Publication Date: 2011-08-17
    Description: A tunable diode laser spectrometer with several unique features has been developed for use in the middle IR. The all-reflective optical system has a dual-beam configuration before the dispersive mode selector to eliminate transit-angle errors at the calibration etalon. By maintaining separated beams through the mode selector, beam combiner losses are avoided. Averaging successive sweeps of the current-modulated laser permits stable reproducible spectral integrations, eliminating etalon thermal errors and producing high photometric sensitivity. Line strengths have been measured using this instrument for eleven transitions in nu4 of (C-12)H4. These include R0 and R1 and nine P-branch transitions in the 1202-1263-per cm range. Techniques for measuring strengths with a diode laser are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; Aug. 15
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  • 26
    Publication Date: 2011-08-17
    Description: Aerosols containing solid, spherical stearic acid particles with a mean diameter of 0.8 micron and a geometric standard deviation of 1.28 were sampled with small bore front-facing aspirating probes in near-sonic and supersonic unheated free jets. The results are compared to compute the sampling error associated with a high-speed jet sample.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Air Pollution Control Association; vol. 30
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  • 27
    Publication Date: 2011-08-17
    Description: In order to relate the measured fringe shift of an interferometer to the density of a medium, the relation between density and refractive index, which is expressed by the specific refractivity, must be known. In the present paper, the specific refractivities of the wind tunnel test gases CF4 and C2F6 are determined in order to verify estimations based on the atomic refractivities of carbon and fluorine. A Twyman-Green two-beam interferometer with a 633-nm He-Ne laser light source was used to measure the specific refractivity as a function of fringe shift as the density of the gas was changed. Values of 0.122 and 0.131 cu cm/g were obtained for CF4 and C2F6 respectively at a temperature of 300 K, which are within 1% of the values computed from the atomic refractivities.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Chemical Physics; 73; July 15
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  • 28
    Publication Date: 2011-08-17
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Environmental Quality; 9; Jan
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  • 29
    Publication Date: 2011-08-17
    Description: The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; May 15
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  • 30
    Publication Date: 2011-08-17
    Description: This paper describes the overall Large Area Crop Inventory Experiment technical approach utilizing the global weather-reporting network and the Landsat satellite to make a quasi-operational application of existing research results, and the accomplishments of this cooperative experiment in utilizing the weather information. Global weather data were utilized in preparing timely yield estimates for selected areas of the U.S. Great Plains, the U.S.S.R. and Canada. Additionally, wheat yield models were developed and pilot tested for Brazil, Australia, India and Argentina. The results of the work show that heading dates for wheat in North America can be predicted with an average absolute error of about 5 days for winter wheat and 4 days for spring wheat. Independent tests of wheat yield models over a 10-year period for the U.S. Great Plains produced a root-mean-square error of 1.12 quintals per hectare (q/ha) while similar tests in the U.S.S.R. produced an error of 1.31 q/ha. Research designed to improve the initial capability is described as is the rationale for further evolution of a capability to monitor global climate and assess its impact on world food supplies.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Applied Meteorology; 19; Jan. 198
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  • 31
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N80-19588)
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Dec. 198
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  • 32
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N79-33530)
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Nov. 198
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  • 33
    Publication Date: 2011-08-18
    Description: The development of agricultural remote sensing systems requires knowledge of agricultural field size distributions so that the sensors, sampling frames, image interpretation schemes, registration systems, and classification systems can be properly designed. Malila et al. (1976) studied the field size distribution for wheat and all other crops in two Kansas LACIE (Large Area Crop Inventory Experiment) intensive test sites using ground observations of the crops and measurements of their field areas based on current year rectified aerial photomaps. The field area and size distributions reported in the present investigation are derived from a representative subset of a stratified random sample of LACIE sample segments. In contrast to previous work, the obtained results indicate that most field-size distributions are not log-normally distributed. The most common field size observed in this study was 10 acres for most crops studied.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Nov. 198
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  • 34
    Publication Date: 2011-08-18
    Description: Using stepwise discriminant analysis on spectral reflectance and spectral emissivity data collected by a Multispectral Scanner and Data System, mounted in an NC-130B aircraft and flown at an altitude of approximately 3 km, spectral bands were ranked as to their usefulness in separating specific rock types and rock alteration products in seven geologically diverse Utah sites. The optimum band for rock discrimination included the 1.18 to 1.30 micron interval, and the optimum combination of bands comprised the 1.18 to 1.30, 4.50 to 4.75, 0.46 to 0.50, 1.52 to 1.73, and 2.10 to 2.36 micron intervals. It is concluded that the spectral interval combination was more successful in differentiating geologic materials than either simulated Multispectral Scanner bands or simulated Thematic Mapper bands.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Sept
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  • 35
    Publication Date: 2011-08-18
    Description: A scaling correlator optical pattern recognition system is described in which a lensless matched spatial filter (with the second Fourier transform lens and the matched spatial filter recorded on the same plate) is used with a first Fourier transform lens that is also an holographic optical element. The matched spatial filter is recorded at one wavelength and correlation is obtained at a second wavelength. Experimental demonstration and output correlation SNR data are reported, together with a comparison of the system's noise level using conventional optics and holographic elements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Communications; 34; Sept
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  • 36
    Publication Date: 2011-08-17
    Description: Visible and near-infrared field spectral reflectance measurements of plutonic rocks were acquired in the 0.45- to 2.45-micron region with a portable field reflectance spectrometer. These spectra were used to determine spectral signatures for the various rock types and to evaluate the separability of these rocks based on their spectral characteristics. A total of 135 samples were divided into 11 groups based on their mineralogy. These 11 groups approximately correspond to traditional rock classifications and include five granitic groups, three gabbroic groups, and three ultramafic groups. The positions, intensity, and presence of iron, CO3(-2), and Al-OH and Mg-OH absorption bands varied among the 11 groups. Each rock group also had a range of albedos characteristic of the group. Stepwise linear discriminant analysis was performed on the spectral data to determine the separability of the 11 groups. Classification accuracy for 30 equally spaced wavelength bands between 0.45 and 2.45 microns was 78% with 10% serious misclassifications. The same analysis was repeated, limiting the spectral data to the wavelength regions corresponding to the proposed Landsat D thematic mapper scanner.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Geophysical Research; 85; May 10
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  • 37
    Publication Date: 2011-08-17
    Description: Photographic images enhanced by the method of Thiourea-S35 autoradiography are evaluated in terms of signal-to-noise ratio, detective quantum efficiency (DQE), and Wiener spectrum analysis using digitized images. It is determined that the original signal-to-noise ratio is not degraded by the intensification process which allows an increase in the practical working DQE as a function of density. These results apply at all spatial frequencies that were tested. The advantage given by autoradiography is the ability to produce usable images from emulsions originally exposed to the low densities corresponding to maximum DQE and movement of faint image densities above the level of the threshold for detection.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astronomical Society of the Pacific; vol. 92
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  • 38
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    Publication Date: 2011-08-17
    Description: The quality of image reconstructions from discrete data suffers not only from the blurring of spatial detail caused by limitations in the spatial frequency response of electrooptical systems, but also from the aliasing generated if spatial detail has been undersampled. Previous studies have observed that reasonable spot intensity profiles and photosensor aperture shapes of equivalent size result in about equal blurring but that some profiles and shapes suppress aliasing better than others. This paper presents quantitative results of the magnitude of aliasing and blurring as a function of random radiance fields typical for natural scenes and of spatial responses and sampling intervals typical for TV cameras and optical-mechanical scanners. These results indicate that aliasing may often be a larger source of degradation than either blurring or electronic noise.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; July 1
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  • 39
    Publication Date: 2011-08-17
    Description: Effective radiant temperatures (ERTs) of five wheat canopies in different stages of development were measured during morning and noon periods. The observed variability in nadir sensor response was quantitatively described as a function of canopy structure and the vertical temperature profile of canopy components. In many cases, the nadir sensor ERT was a poor measure of vegetation temperature due to effects of soil emissions. Strong vertical temperature profiles of vegetation components were also observed. The theory and measurements presented document that remote measurements of vegetation canopy temperatures cannot be made indiscriminately over large spatial regions without consideration of the underlying physical principles.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Applied Optics; 19; July 1
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  • 40
    Publication Date: 2011-08-17
    Description: Red and photographic infrared spectral data of alfalfa were collected at the time of the third and fourth cuttings using a hand-held radiometer for the earlier alfalfa cutting. Significant linear and non-linear correlation coefficients were found between the spectral variables and plant height, biomass, forage water content, and estimated canopy cover. For the alfalfa of the later cutting, which had experienced a period of severe drought stress which limited growth, the spectral variables were found to be highly correlated with the estimated drought scores.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing; 1; Jan
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  • 41
    Publication Date: 2011-08-17
    Description: Simultaneous microwave radar and spectral radiometric data were collected over Lake Erie during March 1978. A theoretical development is presented which interprets the data collected at nadir in terms of changes in the ice thickness and the electromagnetic attenuation coefficient. The theory also addresses the failure of the spectral radiometer to determine ice thickness through observations of quarter wavelength excursions in the reflectivity. Radar data collected off-nadir showed a substantially different behavior compared to that collected near nadir. This difference is attributed to a change in propagation characteristics from quasi-specular return from the ice-water interface to scattering from the rough air-ice interface.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Geophysical Research Letters; 7; Apr. 198
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  • 42
    Publication Date: 2011-08-17
    Description: An apparatus is described in which hydrogen atoms were trapped at temperatures down to 1.1 K in the 11 T field of a large volume superconducting magnet. A high sensitivity thermal detector was used to study trapping and recombination of atoms on the detector surface. The apparatus permits the application of extremely high steady state magnetic fields to study the potential effects of electron spin polarization on the stabilization of hydrogen atoms.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 51; May 1980
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  • 43
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    Publication Date: 2011-08-17
    Description: The microwave approaches for remote sensing of soil moisture centent, snowpack properties, surface water area, and the detection of precipitation over land are discussed. Both active (radar) and passive (radiometry) approaches are considered, and the advantages of microwave sensing are pointed out, including all-weather capability, especially at the longer wavelengths, and greater penetration depth with optical or infrared sensors. Results obtained from ground-based, aircraft, and spacecraft platforms show that microwave systems can monitor the moisture content in the surface soil layer (5 cm thick), and that passive microwave systems can discriminate between light and heavy snowcover, detect the presence of liquid water in the snow, and qualitatively estimate snow water equivalent.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Apr. 198
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  • 44
    Publication Date: 2011-08-17
    Description: A coaxial dual-channel laser system has been developed for the measurement of extinction coefficients of highly absorbing liquids. An empty wedge-shaped sample cell is first translated laterally through a He-Ne laser beam to measure the differential thickness using interference fringes in reflection. The wedge cell is carefully filled with the oil sample and translated through the coaxially positioned dye laser beam for the differential attenuation or extinction measurement. Optional use of the instrumentation as a single-channel extinction measurement system and also as a refractometer is detailed. The system and calibration techniques were applied to the measurement of two crude oils whose extinction values were required to complete the analysis of airborne laser data gathered over four controlled spills.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; Apr. 1
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  • 45
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    Publication Date: 2011-08-17
    Description: Estimating the emergence of a given crop, such as wheat or barley, is proposed using an analytic method which relies on the hypothesis that in the region (lambda = 0.70-1.35 microns) a given crop, after emergence, has a unique spectral profile in time. If the crop emerges early or late, relative to a reference standard determined for a given segment, the profile is displaced but has the same shape. Therefore, given the crop specific constants of the reference profile and a sufficient number of Landsat observations of reflectivity at specific times, the emergence date of a field can be determined.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Mar. 198
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  • 46
    Publication Date: 2011-08-17
    Description: The paper covers the studies presented on nuclear science and nuclear power systems symposiums. The studies deal with nuclear radiation detectors, nuclear circuits and systems, space and medical instrumentation, as well as with environmental and reactor instrumentation. Data preprocessing and acquisition are discussed. Emphasis is placed on the engineered safety features of nuclear systems.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 47
    Publication Date: 2011-08-17
    Description: This note describes some details of recent (successful) attempts of wall proximity corrections for hot-wire measurements performed in a three-dimensional incompressible turbulent boundary layer. A simple and quite satisfactory method of estimating wall proximity effects on hot-wire readings is suggested.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: DISA Information; Feb. 198
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  • 48
    Publication Date: 2011-08-18
    Description: As a part of a follow-on study to the moisture stress detection effort conducted in the Large Area Crop Inventory Experiment (LACIE), a technique utilizing transformed Landsat digital data was evaluated for detecting moisture stress in humid growing regions using sample segments from Iowa, Illinois, and Indiana. At known growth stages of corn and soybeans, segments were classified as undergoing moisture stress or not undergoing stress. The remote-sensing-based information was compared to a weekly ground-based index (Crop Moisture Index). This comparison demonstrated that the remote sensing technique could be used to monitor the growing conditions within a region where corn and soybeans are the major crop.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Aug. 198
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  • 49
    Publication Date: 2011-08-18
    Description: It is difficult to interpret multispectral Landsat earth resources data in areas of rugged and mountainous terrain because of the topographic effect on the sensor response. The objectives of this study were to examine and quantify the topographic effect on the sensor response from a uniform sand surface, to assess a simple theoretical incidence model for modeling the radiance from the surface, and to simulate Landsat sensor response due to the topographic effect. A field experiment was designed to collect data from a large range of slope angles and aspects at a range of solar elevations, using a hand-held radiometer. Analysis of these data showed that the magnitude of the topographic effect varied as a function of the solar elevation, the azimuthal orientation of the slope, and the slope inclination. The field measured variations in spectral response were found to have generally strong correlations with the theoretical model, and it was shown that the applicability of the Lambertian assumption varied within and between data sets. It is concluded that if slope angle, aspect, and solar zenith angle and azimuth are known, a technique incorporating a model to reduce the topographic effect prior to multispectral classification may be developed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Sept
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  • 50
    Publication Date: 2011-08-18
    Description: The dielectric properties of polluted waters are measured with a reflection-type resonant cavity at 1.43 GHz. Very small water samples in quartz tubes of known volume are placed in the center of the maximum electric field. Measurement of the resonance-frequency variation and a change of the cavity's quality factor are used to determine the dielectric properties. The microwave emissivity of the polluted water is then calculated via the Fresnel equation and applied to data reductions of microwave radiometer measurements.
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  • 51
    Publication Date: 2011-08-17
    Description: Limits to low noise equivalent power (NEP) operation of a lithium niobate upconverter are investigated. Upconversion is achieved inside the optical cavity of an Ar-ion laser. Limits to NEP are imposed by limits to conversion efficiency and by noise present in the upconversion process. Conversion efficiency is limited by thermal effects in the lithium niobate. Thermally induced wedging, focusing, and aberrations are caused by the lithium niobate absorption at the 514.5-nm argon pump wavelength. The primary component of noise in the upconverter is due to upconversion of thermal radiation from the lithium niobate crystal. The lowest NEP, at a wavelength of 3.4 microns, achieved in this study was 8.9 x 10 to the -14th W/(Hz to the 1/2 power).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 52
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    Publication Date: 2011-08-17
    Description: The needs for and remote sensing means of global crop forecasting are discussed, and key results of the Large Area Crop Inventory Experiment (LACIE) are presented. Current crop production estimates provided by foreign countries are shown often to be inadequate, and the basic elements of crop production forecasts are reviewed. The LACIE project is introduced as a proof-of-concept experiment designed to assimilate remote sensing technology, monitor global wheat production, evaluate key technical problems, modify the technique accordingly and demonstrate the feasibility of a global agricultural monitoring system. The global meteorological data, sampling and aggregation techniques, Landsat data analysis procedures and yield forecast procedures used in the experiment are outlined. Accuracy assessment procedures employed to evaluate LACIE technology performance are presented, and improvements in system efficiency and capacity during the three years of operation are pointed out. Results of LACIE estimates of Soviet, U.S. and Canadian wheat production are presented which demonstrate the feasibility and accuracy of the remote-sensing approach for global food and fiber monitoring.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Science; 208; May 16
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  • 53
    Publication Date: 2011-08-17
    Description: The interference that the atmosphere poses to analyzing the imagery taken by satellite-borne instruments is discussed, assuming a cloud-free, planar, and horizontally uniform atmosphere. An approximate explicit formula is derived for the earth-atmosphere system nadir-beam reflectivity in terms of the atmospheric parameters, object pixel reflectivity and surrounding area reflectivity, for the limiting case of an optically thin atmosphere. The concepts of the forward-scattering and the backward-scattering optical thickness are introduced, and it is shown that the atmospheric effects in a spectral band depend in a specific fashion on these atmospheric parameters and on the surface spectral reflectivity. In addition, contrast transmittance through the atmosphere, which affects the possibilities of photointerpretation, is discussed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 9; Mar. 198
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  • 54
    Publication Date: 2011-08-17
    Description: A laboratory radiometric method for the rapid determination of green and brown vegetation percentages in clipped grass samples has been developed and tested. The method uses red and photographic infrared radiance or reflectance differences between green and brown vegetation. Mixtures of green and brown material were found to have radiances or reflectances proportional to the percentage of green material present. This method may permit the use of rapid green/brown radiometric determinations to replace the tedious hand sorting now generally used. It may also have application in remote sensing of vegetation ground-truth work where the determination of dry green biomass in clipped samples is necessary.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 9; Mar. 198
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  • 55
    Publication Date: 2011-08-18
    Description: Areas of the Canadian high plains, the Montana and North Dakota high plains, and the steppes of central Russia have been studied in an effort to determine the utility of spaceborne microwave radiometers for monitoring snow depths in different geographic areas. Significant regression relationships between snow depth and microwave brightness temperatures were developed for each of these homogeneous areas. In each of the study areas investigated in this paper, Nimbus-6 (0.81 cm) ESMR data produced higher correlations than Nimbus-5 (1.55 cm) ESMR data in relating microwave brightness temperature to snow depth. It is difficult to extrapolate relationships between microwave brightness temperature and snow depth from one area to another because different geographic areas are likely to have different snowpack conditions.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Dec. 198
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  • 56
    Publication Date: 2011-08-18
    Description: The thermal infrared sensor response from a wheat canopy was extremely non-Lambertian because of spatial variations in energy flow processes; the effective radiant temperature of the sensor varied as much as 13 C with changing view angle. This variation of sensor response was accurately quantified (root-mean-square of deviations between theoretical and measured responses reduced to 1.1 C) as a function of vegetation canopy geometry, vertical temperature distribution of canopy components, and sensor view angle. The results have important implications for optimizing sensor view angles for remote sensing missions.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Dec. 198
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  • 57
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N79-30611)
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Nov. 198
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  • 58
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N80-20768)
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Aug. 198
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  • 59
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    Publication Date: 2011-08-18
    Description: A simulation model has been developed of Galveston Bay, Texas ecosystem. Secondary productivity measured by harvestable species (such as shrimp and fish) is evaluated in terms of man-related and controllable factors, such as quantity and quality of inlet fresh-water and pollutants. This simulation model used information from an existing physical parameters model as well as pertinent biological measurements obtained by conventional sampling techniques. Predicted results from the model compared favorably with those from comparable investigations. In addition, this paper will discuss remotely sensed and conventional measurements in the framework of prospective models that may be used to study estuarine processes and ecosystem productivity.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 60
    Publication Date: 2011-08-17
    Description: Four types of sensors were used to make both dynamic and time-averaged flow measurements in a cold turbine rig to determine the magnitude of errors in time-averaged total-pressure measurement at a station 5 1/2 blade cords downstream from the rotor. The errors turned out to be negligible. The sensors and their intended use are discussed.
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  • 61
    Publication Date: 2011-08-17
    Description: New techniques in nonlinear optical processing are explored, based on the operation of intensity level selection as performed by a Fabry-Perot interferometer containing a phase object. The image being processed is recorded on a medium between the mirrors as a spatially varying phase shift less than pi. The interferometer only transmits light through those portions of the object that corresponds to a single value of the phase and hence to a single intensity level in the input. More complicated operations such as thresholding and analog-to-digital conversion are performed by modulating the light source as the different levels are selected. Photoresist and lithium niobate have been used as phase objects, and experimental data for both are presented. Three kinds of Fabry-Perot interferometers have been used to demonstrate nonlinear processing using coherent and incoherent light. Color images have been produced with black and white inputs and white light illumination.
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  • 62
    Publication Date: 2011-08-17
    Description: The digital recording acquisition subsystem (DRAS) is a wideband digital recording system that can accommodate data sample rates from 0.125 to 8 MHz in binary increments. The implementation of the DRAS for radio interferometry applications in support of the Crustal Dynamics Project is described. The functional and performance characteristics of the equipment and the key aspects of the implementation plan are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 9-14
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  • 63
    Publication Date: 2011-08-18
    Description: A laser beam manifold and particle photography system has been developed for use in fluid velocity measurements. The laser manifold is a device which transforms a single laser beam into several uniform parallel beams. By orienting two manifolds mutually perpendicular, an optical grid can be formed which acts as a reference for fluid velocity measurements. This optical grid is for all practical purposes totally nonperturbing to the flow. Tracer particles moving in the plane of the grid are then photographed to yield fluid velocities that can be measured relative to the optical grid. System construction and theory are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 51; Nov. 198
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  • 64
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    Publication Date: 2011-08-18
    Description: This paper examines the Magsat precision vector magnetometer which is designed to measure projections of the ambient field in three orthogonal directions. The system contains a highly stable and linear triaxial fluxgate magnetometer with a dynamic range of + or - 2000 nT (1 nT = 10 to the -9 weber per sq m). The magnetometer electronics, analog-to-digital converter, and digitally controlled current sources are implemented with redundant designs to avoid a loss of data in case of failures. Measurements are carried out with an accuracy of + or - 1 part in 64,000 in magnitude and 5 arcsec in orientation (1 arcsec = 0.00028 deg).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Johns Hopkins APL Technical Digest; 1; July-Sep
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  • 65
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    Publication Date: 2011-08-18
    Description: The Magsat scalar magnetometer is derived from optical pumping magnetometers flown on the orbiting geophysical observatories. The basic sensor, a cross-coupled arrangement of absorption cells, photodiodes, and amplifiers, oscillates at the Larmor frequency of atomic moments precessing about the ambient field direction. The Larmor frequency output is accumulated digitally and stored for transfer to the spacecraft telemetry stream. In orbit the instrument has met its principal objective of calibrating the vector magnetometer and providing scalar field data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Johns Hopkins APL Technical Digest; 1; July-Sep
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  • 66
    Publication Date: 2011-08-18
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Dec. 198
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  • 67
    Publication Date: 2011-08-18
    Description: A simple and direct method is obtained for assessing the distortion of a Doppler line by a Gaussian instrument function. It is suggested that a close approximation to the width of a Gaussian instrument function, or an almost Gaussian function, may be obtained by measuring a line with a Doppler absorption coefficient. The method is applicable to diode laser measurements, and may be used whenever a Gaussian instrument function is a reasonable approximation to real conditions
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Molecular Spectroscopy; 81; 1980
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  • 68
    Publication Date: 2011-08-18
    Description: The number of radiometric quantizing levels required for satellite monitoring of vegetation resources was evaluated by using in situ collected spectral reflectance data, an atmospheric radiative transfer simulation model, and a satellite sensor simulation model. Reflectance data were converted to radiance data, passed through a model atmosphere to an altitude of 706 km, and subsequently quantized at 16, 32, 64, 128, 256 and 512 digital count levels for Thematic Mapper bands TM3 (0.63-0.69 microns) and TM4 (0.76-0.90 microns). The simulated digital count data were regressed against in situ biological data to quantify the relationship between quantizing levels. Results of the analysis demonstrated that solar zenith angle has an effect on the quantization equivalent change in reflectance, that 256 quantizing levels gave a 1-3% improvement per channel over 64 quantizing levels, and that 256 quantizing levels gave a 1% improvement per channel over 128 quantizing levels. No improvements were found for 256 versus 512 quantizing levels.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing; 1; July-Sep
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  • 69
    Publication Date: 2011-08-18
    Description: Digitally processed Seasat synthetic aperture radar (SAR) imagery of the Denver, Colorado area was examined to assess its potential for mapping urban land cover and the compatibility of SAR derived classes with those described in the U.S. Geological Survey classification system. The entire scene was interpreted to generate a small-scale land cover map. In addition, six subscene enlargements representative of urban land cover categories extant in the area were used as test sites for detailed analysis of land cover types. Two distinct approaches were employed and compared in examining the imagery - a visual interpretation of black-and-white positive transparencies and an automated-machine/visual interpretation. The latter used the Image 100 interactive image analysis system to generate land cover classes by density level slicing of the image frequency histogram.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing; 1; July-Sep
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  • 70
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    Publication Date: 2011-08-18
    Description: The intensity brightness temperature, T(B), of the microwave emission from the soil is determined primarily by its dielectric properties. The large difference between the dielectric constant of water and that of dry soil produces a strong dependence of the soil's dielectric constant on its moisture content. This dependence is effected by the texture of the soil because the water molecules close to the particle surface are tightly bound and do not contribute significantly to the dielectric properties. Since this surface area is a function of the particle size distribution (soil texture), being larger for clay soils with small particles, and smaller for sandy soils with larger particles, the dielectric properties will depend on soil texture. This dependence has been demonstrated by laboratory measurements of the dielectric constant for soils which are briefly summarized. The dependence of the microwave emission on texture is demonstrated by measurements of T(B) from an aircraft platform for a wide range of soil textures. It is concluded that the effect of soil texture differences on the observed T(B) values can be normalized by expressing the soil moisture values as a percentage of field capacity for the soil.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing; GE-18; Oct. 198
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  • 71
    Publication Date: 2011-08-18
    Description: The tilled row structure in agricultural fields is one of the important factors affecting observations of microwave emission from such fields. Measurements of this effect were performed with L-band and X-band radiometers mounted on a mobile truck on a bare 40 m x 45 m row tilled field; the soil moisture content during measurements ranged from 10 to 30% by dry weight. Results showed that the variations of the antenna temperatures with incident angle changed with the azimuth angle measured from the row direction. It is found that the observed difference between horizontally and vertically polarized antenna temperatures is due to the change in the local angle of field emission within the antenna field of view caused by the large-scale row structure.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing; GE-18; Oct. 198
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  • 72
    Publication Date: 2011-08-18
    Description: Recent measurements on the dielectric properties of soils have shown that the variation of dielectric constant with moisture content depends on soil types. The observed dielectric constant increases only slowly with moisture content up to a transition point. Beyond the transition it increases rapidly with moisture content. The moisture value at transition region was found to be higher for high clay content soils than for sandy soils. Many mixing formulas reported in the literature were compared with, and were found incompatible with, the measured dielectric variations of soil-water mixtures. A simple empirical model was proposed to describe the dielectric behavior of the soil-water mixtures. This model employs the mixing of either the dielectric constants or the refraction indices of ice, water, rock, and air, and treats the transition moisture value as an adjustable parameter. The calculated mixture dielectric constants from the model were found to be in reasonable agreement with the measured results over the entire moisture range of 0-0.5 cu cm/cu cm. The transition moistures derived from the model range from 0.16 to 0.33 and are strongly correlated with the wilting points of the soils estimated from their textures. This relationship between transition moisture and wilting point provides a means of estimating soil dielectric properties on the basis of texture information.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing; GE-18; Oct. 198
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  • 73
    Publication Date: 2011-08-18
    Description: Remote measurements of soil moisture contents over bare fields and fields covered with orchard grass, corn, and soybean were made during October 1979 with 1.4 GHz and 5 GHz microwave radiometers mounted on a truck. Ground truth of soil moisture content, ambient air, and soil temperatures was acquired concurrently with the radiometric measurements. The biomass of the vegetation was sampled about once a week. The measured brightness temperatures over bare fields were compared with those of radiative transfer model calculations using as inputs the acquired soil moisture and temperature data with appropriate values of dielectric constants for soil-water mixtures. Good agreement was found between the calculated and the measured results over 10-70 deg incident angles. The presence of vegetation was found to reduce the sensitivity of soil moisture sensing. At 1.4 GHz the sensitivity reduction ranged from approximately 20% for 10-cm tall grassland to over 60% for the dense soybean field. At 5 GHz the corresponding reduction in sensitivity ranged from approximately 70 to approximately 90%.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Physical Research Letters; 7; Oct. 198
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  • 74
    Publication Date: 2011-08-18
    Description: Forested land potentially available for fuelwood harvest within 30 km of Tupper Lake, N.Y. was delineated and classified as to forest using NASA aerial photography and LANDSAT imagery. Published inventory and growth data were used to estimate woody material on the available land. The information submitted to the Energy Office indicates that there is sufficient woody material to supply a 10 MW plant.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Cornell Univ. Remote Sensing Program; 22 p
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  • 75
    Publication Date: 2011-08-18
    Description: Snowpack properties such as water equivalent and snow wetness may be inferred from variations in measured microwave brightness temperatures. This is because the emerged microwave radiation interacts directly with snow crystals within the snowpack. Using vertically and horizontally polarized brightness temperatures obtained from the multifrequency microwave radiometer (MFMR) on board a NASA research aircraft and the electrical scanning microwave radiometer (ESMR) and scanning multichannel microwave radiometer (SMMR) on board the Nimbus 5, 6, and 7 satellites, linear relationships between snow depth or water equivalent and microwave brightness temperature were developed. The presence of melt water in the snowpack generally increases the brightness temperatures, which can be used to predict snowpack priming and timing of runoff.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Microwave Remote Sensing of Snowpack Properties; p 235-248
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  • 76
    Publication Date: 2011-08-18
    Description: The brightness temperature of a natural snow field in northern Europe was studied theortically and experimentally at 5, 12, and 37 GHz for satellite remote sensing applications. A snow model consisting of ice spheres covered by a water shell was used in calculation, taking into account scattering and absorption. The brightness temperature of a natural snow field as a function of view angle was measured from a tower in 1978 and 1979. The measured brightness temperature curves can be fitted with calculated ones by assuming reasonable values for the wetness and the particle size of snow. Experimental results also show that relatively small changes in the snow conditions cause large changes in the brightness temperature. In order to obtain a more controlled situation, experiments were continued in 1980 using a measuring site covered with aluminum sheets and determining the wetness and the particle size in addition to the density and physical temperature.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Goddard Space Flight Center Microwave Remote Sensing of Snowpack Properties; p 225-234
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  • 77
    Publication Date: 2011-08-18
    Description: The natural snow cover on a high altitude alphine test site was monitored with a multi-frequency radiometer for more than three years. Some measurements were also made with a 10.5 GHz scatterometer. The microwave observations are supported by a large set of ground truth data. From year to year a wide variation in the development of the snowpack above and below average was observed. Typical microwave data are presented for the different snow conditions in view of the applicability as signatures for remote sensing.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Goddard Space Flight Center Microwave Remote Sensing of Snowpack Properties; p 203-223
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  • 78
    Publication Date: 2011-08-18
    Description: Recent results indicate that microwave radiometry has the potential for inferring the snow depth and water equivalent information from snowpacks. In order to assess this potential for determining the water equivalent of a snowpack, it is necessary to understand the microwave emission and scattering behavior of the snow at various wavelengths under carefully controlled conditions. Truck-mounted microwave instrumentation was used to study the microwave characteristics of the snowpack in the Colorado Rocky Mountain region during the winters of 1977 to 78 and 7978 to 79. The spectral signatures of C, X, K sub u, and K sub a band radiometers with dual polarization were used, together with measurements of snowpack density, temperature an ram profiles, liquid water content, and rough characterization of the crystal sizes. These data compared favorably with calculated results based on recent microscopic scattering models.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Microwave Remote Sensing of Snowpack Properties; p 169-185
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  • 79
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    Publication Date: 2011-08-18
    Description: Measurements of water equivalence using an active FM-CW microwave system were conducted over the past three years at various sites in Colorado, Wyoming, and California. The measurement method is described. Measurements of water equivalence and stratigraphy are compared with ground truth. A comparison of microwave, federal sampler, and snow pillow measurements at three sites in Colorado is described.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Goddard Space Flight Center Microwave Remote Sensing of Snowpack Properties; p 119-129
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  • 80
    Publication Date: 2011-08-18
    Description: An electromagnetic system is described for measuring the dielectric constant and attenuation of snow samples in the frequency range of 4 to 12 GHz. System components consists of a swept-frequency source, microwave horns, network analyzer, and XY plotter. The procedure for calibrating the effect of wetness on the snow properties is described. Equations are given that express the experimentally determined relation between attenuation per unit length and volume percent wetness at any frequency between 4 and 12 GHz. permittivity can be calculated from the snow density, attenuation per unit length, and frequency. Some applications of the techniques are described such as runoff forecasting from mountain snowpacks.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Goddard Space Flight Center Microwave Remote Sensing of Snowpack Properties; p 93-117
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  • 81
    Publication Date: 2011-08-18
    Description: Snow is treated as a heterogeneous dielectric material consisting of ice, air, and water. The greater difference in the high frequency relative permittivity of dry snow and water allows to determine the liquid water content by measurements of the relative permittivity of snow. A plate condenser with a volume of about 1000 cv cm was used to measure the average liquid water content in a snow volume. Calibration was carried out using a freezing calorimeter. In order to measure the liquid water content in thin snow layers, a comb-shaped condenser was developed, which is the two dimensional analogon of the plate condenser. With this moisture meter the liquid water content was measured in layers of a few millimeters in thickness, whereby the effective depth of measurement is given by the penetration depth of electric field lines which is controlled by the spacing of the strip lines. Results of field measurements with both moisture meters, the plate condenser and the comb-shaped condenser, are given.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Goddard Space Flight Center Microwave Remote Sensing of Snowpack Properties; p 69-92
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  • 82
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    Publication Date: 2011-08-18
    Description: The mixing theory of Polder and Van Santen is revised for application to three cases of wet snow. The dielectric constant is calculated for a range of liquid contents and porosities. These calculated values compare favorably with experimental data for the two cases in which data available. The application to a snow cover with a heterogeneous distribution of liquid is discussed. The possibility of applying this theory the calculate the imaginary part of the dielectric constant must be explored further.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Goddard Space Flight Center Microwave Remote Sensing of Snowpack Properties; p 21-39
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  • 83
    Publication Date: 2011-08-18
    Description: California's Snow Survey Program and water supply forecasting procedures are described. A review is made of current activities and program direction on such matters as: the growing statewide network of automatic snow sensors; restrictions on the gathering hydrometeorological data in areas designated as wilderness; the use of satellite communications, which both provides a flexible network without mountaintop repeaters and satisfies the need for unobtrusiveness in wilderness areas; and the increasing operational use of snow covered area (SCA) obtained from satellite imagery, which, combined with water equivalent from snow sensors, provides a high correlation to the volumes and rates of snowmelt runoff. Also examined are the advantages of remote sensing; the anticipated effects of a new input of basin wide index of water equivalent, such as the obtained through microwave techniques, on future forecasting opportunities; and the future direction and goals of the California Snow Surveys Program.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Goddard Space Flight Center Microwave Remote Sensing of Snowpack Properties; p 11-17
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  • 84
    Publication Date: 2011-08-18
    Description: Both manually collected snow-course data and telemetered information from SNOTEL sites throughout the western United States are used to make forecasts of streamflow. Although these conventional methods have proven highly reliable over the years, they still exhibit some shortcomings. Active and passive microwave remote sensing systems recently developed and tests present the potential to eliminate some negative aspects associated with other types of sensors currently in use. Because of their ability to see through the snowpack they offer a unique opportunity to improve snowpack measurement techniques. As yet neither the active nor passive system is developed sufficiently to supplant existing methods in operational telemetry networks. Active microwave sensors are the most promising for the near future and are being used in research and development programs to study snow pillow performance in the SNOTEL system.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Goddard Space Flight Center Microwave Remote Sensing of Snowpack Properties; p 1-10
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  • 85
    Publication Date: 2011-08-18
    Description: Mapping of minor lineaments from radar imagery of the rain forest in southeast Peru is biased due to the selective suppression of some topography which results from the observation geometry of the imaging radar system and the varied perception of lineaments on the imagery by different interpreters. Team analysis of the imagery compensates for several of the sources of bias, and results in the clear recognition of differing regimes within the regional fracture field in the study area.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 502-507
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  • 86
    Publication Date: 2011-08-18
    Description: Surface deposits in the Bristol Lake/Granite Mountains area, Mojave Desert, California were mapped using high resolution 3 cm wavelength radar images. The surface deposits range from silt to boulders in size and were separated into six radar-rock units on the basis of radar return signatures (brightness and texture) and geomorphic expression. Field reconnaissance of the six units showed that the brightness of the radar signatures on the images correlates with the surface roughness of each unit. Two major radar signatures anomalies were noted during the study. A dark radar signature for the large sand ridges in the Kelso Dunes area and a distinct northwest trending contrast boundary between bright and dark radar signatures in the Bristol Dry Lake area. Field reconnaissance of the two areas indicated that near surface moisture may be the cause of dark signatures. Dune areas with little to no vegetation produce a dark signature, whereas areas with sparse to moderate vegetation produce an intermediate to dark signature.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 439-456
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  • 87
    Publication Date: 2011-08-18
    Description: Geological experiments and surveys conducted by BRGM and GDTA members to evaluate interest in SLAR image interpretation are summarized. Two surveys were selected for presentation: Les Vans (Massif central, France) and Guyana (South America). They have permitted a comparison between different types of SLAR: Goodyear, Motorola, JPL, and Vigie in term of lithological and structural applications. On the Les Vans test site conclusions reached concern radiometry, which is better on L-band imagery, polarization, HV being more useful than HH for geological mapping in an L-band system, wavelength and illuminations. Over Guyana, the use of Goodyear X-band SLAR enables satisfactory geological and structural mapping under heavy equatorial forest with cloud cover conditions. A differential program was developed for fracture filtering and image enhancement with a coherent light laser, and significant results were obtained.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 417-438
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  • 88
    Publication Date: 2011-08-18
    Description: A geological study of a 27,500 sq km area in the Los Andes region of northwestern Venezuela was performed which employed both X-band radar mosaics and computer processed Landsat images. The 3.12 cm wavelength radar data were collected with horizontal-horizontal polarization and 10 meter spatial resolution by an Aeroservices SAR system at an altitude of 12,000 meters. The radar images increased the number of observable suspected fractures by 27 percent over what could be mapped by LANDSAT alone, owing mostly to the cloud cover penetration capabilities of radar. The approximate eight fold greater spatial resolution of the radar images made possible the identification of shorter, narrower fractures than could be detected with LANDSAT data alone, resulting in the discovery of a low relief anticline that could not be observed in LANDSAT data. Exploration targets for petroleum, copper, and uranium were identified for further geophysical work.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 367-384
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  • 89
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    Publication Date: 2011-08-18
    Description: The present state of radar mapping is reviewed. Emphasis is on radargrammetric mapping with single images, stereo pairs, and block adjustment. Applications to thematic mapping are also addressed. Examples presented concern radar mosaicking, sea ice study and extraterrestrial mapping.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 307-335
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  • 90
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    Publication Date: 2011-08-18
    Description: The use of terrain imaging radar to extract elevation information by stereo viewing and measurement is discussed. Either a three dimensional visual model or elevation measurements may be obtained by simultaneous viewing or differential measurement of images obtained by a side-looking radar from two different flightpaths. Expressions describing radar image geometry, model vertical exaggeration, and stereo measurement accuracy are derived. The dependence of the exaggeration and accuracy on system parameters and key system errors is derived, discussed, and illustrated by application to several airborne and spaceborne systems and system concepts, and the results of some preliminary measurements of imagery from two airborne and one spaceborne system are given.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 336-350
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  • 91
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    Publication Date: 2011-08-18
    Description: Imaging of Togo in 1977 with SLAR provided the data required for the production of map controlled radar mosaics at a scale of 1:200,000 with 95 percent of all control points at that scale within + or - 4.0 millimeters of true positions. The moasics served as the base for the generation of a revised geologic map of Togo. Aided by two looks, numerous revisions resulted, not only with the addition of previously unknown structural features, a revision of age relationships, and the refinement of unit boundaries, but also with the repositioning of rock units and the reorientation of major faults.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 351-364
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  • 92
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    Publication Date: 2011-08-18
    Description: A series of models which attempt to describe more accurately the physical geometry of Earth/land targets is presented. Theoretical calculations are included to illustrate model behavior. Variations with respect to various systems and target parameters are included.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 200-222
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  • 93
    Publication Date: 2011-08-18
    Description: Satellite synthetic aperture radar (SAR) images is evaluated in terms of its geologic applications. The benchmark to which the SAR images are compared is LANDSAT, used both for structural and lithologic interpretations.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 151-167
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  • 94
    Publication Date: 2011-08-18
    Description: The terrain-surface features of the Appalachian Valley and Ridge province were analyzed using Seasat synthetic aperture radar imagery. Particular attention was given to determining the efficiency and capability of this microwave imaging system for geologic mapping.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 75-113
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  • 95
    Publication Date: 2011-08-18
    Description: A number of volcanic fields and sand dune fields in the western part of North America were studied using aircraft and Seasat synthetic aperture radar images and LANDSAT images. The capability of radars with different characteristics (i.e., frequency, polarization and look angles was assessed to identify and map different volcanic features, lava flows and sand dune types. It was concluded that: (1) volcanic features which have a relatively large topographic expression (i.e., cinder cones, collapse craters, calderas, etc.) are easily identified; (2) lava flows of different ages can be identified, particularly on the L-band images; and (3) sand dunes are clearly observed and their extent and large scale geometric characteristics determined, provided the proper imaging geometry exists.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 114-150
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  • 96
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    Publication Date: 2011-08-17
    Description: The astrometric application of the Wide Field Camera and the Planetary Camera is reviewed. It is shown that the digital image centering algorithms can yield a positional accuracy of 0.1 milli-arcsecond. Deconvolution of CCD's sensitivity, non-flatness of the filters, and crinkling of the CCD surface may limit the positional accuracy of 1 milli-arcsecond.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 97
    Publication Date: 2011-08-17
    Description: The thermal response of the fused silica dome filter in an earth radiation budget WFOV shortwave channel conceptual design and the impact of that response on the channel measurement, is described. Attention is given to results from design definition and performance analysis studies. Consideration is given to problems associated with achieving the desired levels of confidence in a high accuracy filtered earth radiation budget WFOV radiometer. Finally, design approaches, ground calibration, and data reduction techniques that minimize measurement uncertainties are covered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; June 1
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  • 98
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    Publication Date: 2011-08-17
    Description: The permittivity and attenuation of prepared samples of wet snow are measured and curves presented showing the dependence of these quantities of snow wetness and frequency. Equations are given that express the experimentally determined relation between attenuation per unit length and volume-percent wetness at any frequency between 4 and 12 GHz. Additional equations are given for the calculation of permittivity from the snow density, attenuation per unit length, and frequency. Water retention characteristics of snow are described. Some applications of the techniques, such as runoff forecasting from mountain snowpacks, are proposed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Applied Physics; 51; May 1980
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  • 99
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    Publication Date: 2011-08-17
    Description: The paper discusses the Thematic Mapper (TM), a multispectral earth resources sensor that will be launched on the Landsat-D satellite. The TM will operate in a circular, near-polar orbit of 750-km altitude and will scan a swath of earth 185 km wide. One TM mirror is a moving scan mirror, active during the forward and reverse scans; the final design of this component incorporates a mirror which has the required linearity and is not influenced by structural vibration. Another TM component that presented a design difficulty was the optical metering structure which has to be thermally stable across the temperature range in the instrument's orbital environment and duty cycle.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Geoscience and Remote Sensing; GE-18; Apr. 198
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  • 100
    Publication Date: 2011-08-17
    Description: A new method of ultrasonic frequency analysis is introduced which employs frequency-tracked gated RF drive pulses rather than shock-excited broadband spikes to generate the ultrasonic waveform. The new technique, a variation of the sampled-continuous wave technique, eliminates problems associated with finite pulse widths of conventional methods. It is shown to yield correct ultrasonic wave velocity measurements of the sample irrespective of receiver gate width or position provided any portions of two successive echoes are gated simultaneously into the spectrum analyzer. The experimental observations are substantiated by a theoretical model based on the time-frequency domain formulation of ultrasonic frequency analysis.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Acoustical Society of America; vol. 67
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