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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Application of remote sensing to reconnaissance geologic mapping and mineral exploration

A method of mapping geology at a reconnaissance scale and locating zones of possible hydrothermal alteration has been developed. This method is based on principal component analysis of Landsat digital data and is applied to the desert area of the Chagai Hills, Baluchistan, Pakistan. A method for airborne spectrometric detection of geobotanical anomalies associated with prophyry Cu-Mo mineralization at Heddleston, Montana has also been developed. This method is based on discriminants in the 0.67 micron and 0.79 micron region of the spectrum.

Birnie, R. W.↗
NASA NTRS1979

Multispectral histogram normalization contrast enhancement

A multispectral histogram normalization or decorrelation enhancement which achieves effective color composites by removing interband correlation is described. The enhancement procedure employs either linear or nonlinear transformations to equalize principal component variances. An additional rotation to any set of orthogonal coordinates is thus possible, while full histogram utilization is maintained by avoiding the reintroduction of correlation. For the three-dimensional case, the enhancement procedure may be implemented with a lookup table. An application of the enhancement to Landsat multispectral scanning imagery is presented.

Soha, J. M.↗
NASA NTRS1979

Squalenes, phytanes and other isoprenoids as major neutral lipids of methanogenic and thermoacidophilic 'archaebacteria'

The neutral lipids from nine species of methanogenic bacteria (five methanobacilli, two methanococci, a methanospirillum and a methanosarcina) and two thermoacidophilic bacteria (Thermo-plasma and Sulfolobus) have been analyzed. The neutral lipids were found to comprise a wide range (C14 to C30) of polyisoprenyl hydrocarbons with varying degrees of saturation. The principal components represented the three major isoprenoid series (C20 phytanyl, C25 pentaisoprenyl, and C30 squalenyl), in contrast with the neutral lipids of extreme halophiles, which consist predominantly of C2O (phytanyl, geranylgeraniol), C30 (squalenes), C40 (carotenes) and C50 (bacterioruberins compounds), as reported by Kates (1978). These results, which indicate strong general similarities between genetically diverse organisms, support the classification of these organisms in a separate phylogenetic group. The occurrence of similar isoprenoid compounds in petroleum and ancient sediments and the fact that the methanogens, halophiles and thermoacidophiles live in conditions presumed to have prevailed in archaen times suggest that the isoprenoid compounds in petroleum compounds and sediment may have been directly synthesized by organisms of this type

Tornabene, T. G.↗
NASA NTRS1979

Experimental measurements of the rotating frequencies and mode shapes of a full scale helicopter rotor in a vacuum and correlations with calculated results

This paper presents results of an experimental program conducted to obtain data which can be used for correlations of rotor blade dynamic analyses. Measurements were made of the rotating frequencies and mode shapes of a representative full-scale, two-bladed helicopter rotor in a vacuum. The blades were cantilevered to the hub. Mode shape data were obtained optically using a system of cameras developed specifically for this purpose. Excitation of the rotor was provided by vertical oscillatory motion of the hub. To compare experimental and analytical results, correlations of some experimental measurements with calculations from an existing blade modes computer program based on a Holzer-Myklestad procedure are presented, and the differences between the results are discussed. The experimental and analytical natural frequencies were generally in good agreement as were the principal components of the modal deflections for the flap and lag modes. The torsion mode shape indicated disagreement between the measured and calculated results in regard to the amount of flap and lag motions present in this mode, while the spanwise variations of the measured and calculated torsional components were in agreement.

Lee, B. L.↗
NASA NTRS1979

Application of digital image processing techniques to astronomical imagery, 1979

Several areas of applications of image processing to astronomy were identified and discussed. These areas include: (1) deconvolution for atmospheric seeing compensation; a comparison between maximum entropy and conventional Wiener algorithms; (2) polarization in galaxies from photographic plates; (3) time changes in M87 and methods of displaying these changes; (4) comparing emission line images in planetary nebulae; and (5) log intensity, hue saturation intensity, and principal component color enhancements of M82. Examples are presented of these techniques applied to a variety of objects.

Lorre, J. J.↗
NASA NTRS1980

Atmospheric corrections to passive microwave observations of the ocean

Microwave observations of the ocean surface are contaminated to a greater or lesser degree by the overlying atmosphere. The principal components of the atmosphere contributing to this contamination are molecular oxygen, water vapor, and water droplets. By means of measurements at several well-chosen frequencies, these atmospheric parameters may be removed from ocean observations and themselves retrieved as a by-product. This is the basic concept of the Scanning Multifrequency Radiometer (SMMR). These corrections may be made by quasi-linear means to useful accuracies, even in the presence of moderate rain.

Wilheit, T.↗
NASA NTRS1980

Middle infrared multispectral aircraft scanner data - Analysis for geological applications

Multispectral middle IR (8-13 microns) data were acquired with an aircraft scanner over Utah. Because these digital image data were dominated by temperature, all six channels were highly correlated. Extensive processing was required to allow geologic photointerpretation based on subtle variations in spectral emittance between rock types. After preliminary processing, ratio images were produced and color ratio composites created from these. Sensor calibration and an atmospheric model allowed determination of surface brightness, temperature, emittance, and color composite emittance images. The best separation of major rock types was achieved with a principal component transformation, followed by a Gaussian stretch, followed by an inverse transformation to the original axes.

Kahle, A. B.↗
NASA NTRS1980

Visual enhancement of images of natural resources: Applications in geology

The principal components technique for use in multispectral scanner LANDSAT data processing results in optimum dimensionality reduction. A powerful tool for MSS IMAGE enhancement, the method provides a maximum impression of terrain ruggedness; this fact makes the technique well suited for geological analysis.

Dejesusparada, N.↗
NASA NTRS1980

Evaluation of multispectral middle infrared aircraft images for lithologic mapping in the East Tintic Mountains, Utah

Six channels of multispectral middle infrared (8 to 14 micron) aircraft scanner data were acquired over the East Tintic mining district, Utah. This area has high relief and moderate vegetation and consists mainly of Tertiary silicic igneous rocks and Paleozoic quartzite and carbonate rocks that have been locally hydrothermally altered. These digital-image data were computer processed to create a color-composite image based on principal component transformations. Color differences in this image are related to the spectral differences in the surface material and allow discrimination of several rock types, depending primarily on their silica content. When combined with a visible and near infrared color-composite image from a previous flight, with limited field checking, it is possible to discriminate quartzite, carbonate rocks, quartz latitic and quartz monzonitic rocks, latitic and monzonitic rocks, silicified altered rocks, argillized altered rocks, and vegetation.

Kahle, A. B.↗
NASA NTRS1981

Drift and dispersion studies of ocean-dumped waste using Landsat imagery and current drogues

The drift and dispersion of industrial acid wastes dumped 64 km off the Delaware coast were investigated using 16 Landsat images. Waste plume drift velocities and spread rates were obtained, and principal component analysis was performed to discriminate the acid waste from other pollutants. Waste plumes averaged drifting rates from 0.59 km/hr to 3.39 km/hr into the southwest quadrant, and remained above the thermocline, which formed at depths ranging from 13 m to 24 m. Rapid waste movement toward shore occurred primarily during storms, although plumes were rapidly dispersed and diluted at spread rates in excess of 4 cm/sec. Landsat data analysis also indicates plume width increase of about 1.5 cm/sec during calm sea conditions, which is also in agreement with Falk's (1974) estimates of plume dilution.

Klemas, V.↗
NASA NTRS1981

Urban area update procedures using Landsat data

Landsat digital enhancements and classification maps are shown to be useful for updating the urban expansion of standard metropolitan statistical areas on a macro scale. Automated procedures for detecting nonurban to urban land coverage change using multitemporal Landsat data are investigated for five metropolitan areas, showing an overall delineation similar to that obtained from large scale aerial photography. The evaluated change detection procedures include image differencing, principal component transformation prior to differencing, and post classification comparison. Results show that image differencing techniques in MSS band 5 provide the most accurate land cover change detections.

Toll, D. L.↗
NASA NTRS1980

A study of the comparative effects of various means of motion cueing during a simulated compensatory tracking task

NASA's Langley Research Center conducted a simulation experiment to ascertain the comparative effects of motion cues (combinations of platform motion and g-seat normal acceleration cues) on compensatory tracking performance. In the experiment, a full six-degree-of-freedom YF-16 model was used as the simulated pursuit aircraft. The Langley Visual Motion Simulator (with in-house developed wash-out), and a Langley developed g-seat were principal components of the simulation. The results of the experiment were examined utilizing univariate and multivariate techniques. The statistical analyses demonstrate that the platform motion and g-seat cues provide additional information to the pilot that allows substantial reduction of lateral tracking error. Also, the analyses show that the g-seat cue helps reduce vertical error.

Mckissick, B. T.↗
NASA NTRS1982

Measuring Hydrogen Properties in Aluminum

System in use at Langley Research Center measures concentration and diffusion coefficient of hydrogen in pure aluminum. Principal components are high-temperature ultra-high-vacuum furnace and quadrupole mass spectrometer. Quantities of hydrogen and other gases that evolve from heated metal are measured in real time and correlated with data on aluminum porosity.

Outlaw, R. A.↗
NASA NTRS1982

Mobility aid for the blind

A project to develop an effective mobility aid for blind pedestrians which acquires consecutive images of the scenes before a moving pedestrian, which locates and identifies the pedestrian's path and potential obstacles in the path, which presents path and obstacle information to the pedestrian, and which operates in real-time is discussed. The mobility aid has three principal components: an image acquisition system, an image interpretation system, and an information presentation system. The image acquisition system consists of a miniature, solid-state TV camera which transforms the scene before the blind pedestrian into an image which can be received by the image interpretation system. The image interpretation system is implemented on a microprocessor which has been programmed to execute real-time feature extraction and scene analysis algorithms for locating and identifying the pedestrian's path and potential obstacles. Identity and location information is presented to the pedestrian by means of tactile coding and machine-generated speech.

Source record↗
NASA NTRS1981

Lunar volcanic glasses and their constraints on mare petrogenesis

The compositional properties of volcanic glasses from the Apollo 11, 14, 15 and 16 landing sites are examined and implications of the results for mare basalt petrogenesis and deep lunar structures are discussed. Major-element and nickel analyses were performed on the glasses using electron probe techniques, and R-mode principal component analysis was performed on the 19 different compositions of glass distinguished. The glasses are found to form two distinct chemical arrays based on the major elements and Ni. The presence of two chemically isolated cumulate systems in the mantle at different depths is thus inferred, and a model is developed for mare petrogenesis in which each system was itself composed of two lithologic components that underwent hybridization, assimilation or mixing to generate the large compositional range of magmas represented by the lunar volcanic glasses. The surface-correlated elements associated with the volcanic glasses are attributed to another reservoir in the deep interior which may be responsible for gas emissions causing lunar transient phenomena. The model developed allows predictions to be made concerning the liquidus phase relations, trace and radiogenic element distributions, nonradiogenic isotope compositions and sample ages.

Delano, J. W.↗
NASA NTRS1982

Containerless melting and solidification of materials with an aerodynamic levitation system

A simple aerodynamic system which can heat, melt, cool, and solidify (in a containerless fashion) small, roughly spherical (diameter 1.5-4 mm) samples of materials is described. The principal components of the system are an aerodynamic levitation tube and an elliptical radiant heater. The materials processed, i.e., melted and resolidified, in the system include lead and an alkali borosilicate glass. The processing of a glass bead is described. In addition, the physical phenomena which may generate the levitation force in the tube are briefly discussed.

Oran, W. A.↗
NASA NTRS1982

Digital overlay of cartographic information on Landsat MSS data for soil surveys

Cartographic soils data were digitized, spatially registered, and merged with processed Landsat image data. The Landsat Multispectral Scanner Subsystem (MSS) image data were used to generate a thematic map representing different soil surface characteristics and an enhanced image. The thematic map was generated using supervised and unsupervised classification procedures. The enhanced image was generated by performing a linear contrast stretch on data altered by a principal components transformation. Although both procedures yielded images useful for soil unit delineation, image enhancement was determined to be more suitable because it was more expedient and inexpensive. Enhanced images cost $0.06 per hectare, spectral classifications cost $0.08 per hectare. The overlay of cartographic data on Landsat data facilitates comparisons between the various processing methods used for soil unit boundary determination, delineation, and verification. This technique also provides for accurate and expedient spatial referencing for field observations and cartographic correlation.

Imhoff, M. L.↗
NASA NTRS1982

Analysis of atmosphere-sea ice interactions in the Arctic basin using ESMR microwave data

Data from the Electrically Scanning Microwave Radiometer (ESMR) on Nimbus-5 are used to determine the spatial and temporal patterns of change in microwave brightness signatures of Arctic sea ice during a full annual cycle (1973/74). Interactions of ice conditions with the atmosphere are examined using grid point data for surface air temperature and atmospheric pressure. Principal components analysis is used to examine the major elements present in the microwave and atmospheric data. Component scores from these analyses are then used in a canonical correlation analysis to determine interassociations present between the ice and atmosphere in the Beaufort Sea and the European sectors on a synoptic time scale. The synoptic weather conditions associated with the pattern of snow melt on the ice in spring 1974 are described, and a clarification of possible alternative interpretations of features identified as polynyi occurring at 80-85 deg N during the late summer 1974 is presented.

Crane, R. G.↗