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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Continued implementation and testing of a Neighborhood Office Center (NOC) and integration of the NOC with an administrative correspondence management information system

The concept of decentralized (remote) neighborhood offices, linked together through a self-sustaining communications network for exchanging voice messages, video images, and digital data was quantitatively evaluated. Hardware and procedures for the integrated multifunctional system were developed. The configuration of the neighborhood office center (NOC) is explained, its production statistics given, and an experiment for NOC network integration via satellite is described. The hardware selected for the integration NOC/management information system is discussed, and the NASA teleconferencing network is evaluated.

Source record↗
NASA NTRS1977

A study of Minnesota land and water resources using remote sensing

The author has identified the following significant results. Both LANDSAT imagery and digital data were studied for usefulness in surveying water conditions of Minnesota lakes. Initial consideration was given to analysis of LANDSAT image densities because of the low technologic and cost requirements. The techniques employed, however, yield inconsistent and unreliable results. A set of criteria are given for using LANDSAT data in identification of three categories of particulate contaminants in Lake Superior. A linear transformation giving the relationship between the residual LANDSAT intensities and concentrations of three contaminants was obtained from correlation of remote sensing data with insitu measurements. LANDSAT imagery was found useful in placing peat bogs and fens in their respective geologic settings. Artificial disturbances and drainageways in peatlands could be recognized and classified.

Shepherd, W. G.↗
NASA NTRS1977

Monitoring surface albedo change with Landsat

A pronounced decrease of the surface albedo (reflectivity) has been observed in an area in the Northern Sinai, fenced-in in the summer of 1974. Analysis of the Landsat Multispectral Scanner System digital data from an April 1977 pass indicates a reduction in the albedo in the exclosure by 13%, as compared to the outside, which continues to be subjected to overgrazing and anthropogenic pressures. The reduction of reflectivity is approximately the same in all the spectral bands, and is therefore attributable to accumulation of dead plants and plant debris, and not directly to live vegetation.

Otterman, J.↗
NASA NTRS1977

Remote sensing and geographically based information systems

A structure is proposed for a geographically-oriented computer-based information system applicable to the analysis of remote sensing digital data. The structure, intended to answer a wide variety of user needs, would permit multiple views of the data, provide independent management of data security, quality and integrity, and rely on automatic data filing. Problems in geographically-oriented data systems, including those related to line encoding and cell encoding, are considered.

Cicone, R. C.↗
NASA NTRS1978

Evidence for a supermassive object in the nucleus of the galaxy M87 from SIT and CCD area photometry

Results are presented for broadband three-color (BVR) photometric observations of the peculiar elliptical radio galaxy M87, which were obtained with digital two-dimensional SIT and CCD detector systems on the Palomar 60-in. and 200-in. telescopes. The observations and the reduction procedures for the digital data are outlined, the luminosity profile of M87 is given, and a nuclear luminosity spike is found to be centered within 0.02 arcsec of the center of M87. Attempts are made to fit various theoretical models to the luminosity profile, and a satisfactory fit is obtained between the observed profile and a model involving a massive black hole in the galactic nucleus. A model-independent dynamical analysis of the central regions is performed which indicates that the nucleus of M87 contains a supermassive object of about 5 billion solar masses with a radius of no more than 100 pc and an M/L ratio of at least 60. The possible nature of this object is considered, and it is concluded that M87 is probably the most plausible candidate for a massive black hole in a galactic nucleus.

Young, P. J.↗
NASA NTRS1978

Tracking performance of unbalanced QPSK demodulators. I - Biphase Costas loop with passive arm filters

Unbalanced quadriphase-shift-keying (QPSK) is an attractive means for transmitting two digital data streams which in general have different average powers, data rates, and data formats. Previous analyses of the tracking performance of Costas loop demodulators of unbalanced QPSK have accounted only for the filtering effect produced by the loop's two arm filters on the equivalent additive noise perturbing the loop. When the bandwidth of these filters is selected on the basis of the order of the data rate, as is typical of optimum Costas loop design, the filtering degradations of the data modulations themselves and the cross-modulation noise produced by their multiplication in the loop often cannot be neglected. The purpose of this paper is to incorporate these additional filtering effects into the analysis. Many of the results obtained herein are in the form of closed-form expressions which can easily be evaluated numerically for design and performance prediction purposes.

Simon, M. K.↗
NASA NTRS1977

Determination of potential solar power sites in the United States based upon satellite cloud observations

The use of cloud images in the visual spectrum from the SMS/GOES geostationary satellites to determine the hourly distribution of sunshine on a mesoscale in the continental United States excluding Alaska is presented. Cloud coverage and density as a function of time of day and season are evaluated through the use of digital data processing techniques. Low density cirrus clouds are less detrimental to solar energy collection than other types; and clouds in the morning and evening are less detrimental than those during midday hours of maximum insolation. Seasonal geographic distributions of cloud cover/sunshine are converted to langleys of solar radiation received at the earth's surface through relationships developed from long term measurements at six widely distributed stations.

Hiser, H. W.↗
NASA NTRS1978

The Space Shuttle Ground Terminal Delta Modulation System

Shuttle voice processing uses a Variable Slope Delta Modulation scheme which is a variant of the ABATE algorithm. This paper summarizes the ground terminal subsystem which processes the multiplexed voice and telemetry data digital sequence in the downlink processing and digitizes the voice signal in the uplink processing. The Delta Modulation System (DMS) performance characteristics are given in terms of an intelligibility test score and in terms of time and frequency responses measured on a production system developed for NASA Goddard Space Flight Center. Implementation details of the encoder and decoder algorithms are given in terms of the circuit logic used to implement them.

Auger, R. L.↗
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 NTRS1978

Utilizing the dust streak-dryline intersection phenomenon in severe local storm forecasting

Several characteristics of a major dust storm on 20 February 1976 are presented. Four primary areas of discussion are considered: dust storm characteristics; comparisons between the cell detection capabilities of the geosynchronous satellite and radar; the use of the NASA Atmospheric and Oceanographic Information Processing System (an interactive image processing system) for interactive display of visual and IR digital data to obtain qualitative and quantitative results on specific dust cloud and cloud top characteristics; and evidence that the intersection downwind of dust clouds (streaks) with the dryline can be used to forecast the initial storm development on the dryline and that the dust clouds detected on 20 February 1976 are a reflection of upper tropospheric speed maxima, which according to McNulty (1978) and others, are associated with rapid severe convective local storm development.

Anthony, R. W.↗
NASA NTRS1979

Wetland classification on the Alaskan North Slope

An interactive supervised wetland classification was performed on Landsat digital data for three sites on the North Slope of Alaska. Color-coded classification maps identifying 10 wetland subcategories were produced. Field observations, topographic maps, and aerial photographs were employed as collateral data in classifying and verifying the Landsat information.

Morrow, J. W.↗
NASA NTRS1979

Seasat visible and infrared radiometer

The visual and infrared radiometer (VIRR) system on Seasat is described, and methods used in the geophysical evaluation of digital data from this system are discussed. The main function of the radiometer system is to provide images of visual reflection and thermal infrared emission from ocean, coastal and atmospheric features to facilitate interpretation of data from other Seasat sensors; in addition, it is expected to provide some derived quantitative measurements of such factors as sea-surface temperature and cloud-top height. Some results of a statistical comparison of Seasat VIRR-derived sea-surface temperatures in a cloud-free region with a National Oceanic and Atmospheric Administration (NOAA) analysis based on surface measurements made in the same region are presented. The data sets were in agreement of plus or minus 1.7 deg K root-mean-square. The means of the two sets of temperatures were 293.9 deg K (VIRR) and 293.1 deg K (NOAA), and the standard deviations were 3.21 deg and 3.2 deg K, respectively.

Mcclain, E. P.↗
NASA NTRS1979

Detecting transition in agricultural systems

Remote sensing of agricultural phenomena has been largely concentrated on analysis of agriculture at the field level. Concern has been to identify crop status, crop condition, and crop distribution, all of which are spatially analyzed on a field-by-field basis. A more general level of abstraction is the agricultural system, or the complex of crops and other land cover that differentiate various agricultural economies. The paper reports on a methodology to assist in the analysis of the landscape elements of agricultural systems with Landsat digital data. The methodology involves tracing periods of photosynthetic activity for a fixed area. Change from one agricultural system to another is detected through shifts in the intensity and periodicity of photosynthetic activity as recorded in the radiometric return to Landsat. The Landsat-derived radiometric indicator of photosynthetic activity appears to provide the ability to differentiate agricultural systems from each other as well as from conterminous natural vegetation.

Neary, P. J.↗
NASA NTRS1979

NASA/Princeton digital avionics flight test facility

This paper describes a general-aviation digital avionics flight-test facility being jointly developed by the Flight Dynamics Laboratory of Princeton University and NASA/Langley Research Center. This facility consists of the Princeton avionics research aircraft (ARA) and NASA/Langley's digital avionics research (DARE) system. The ARA is a fully instrumented five-degree-of-freedom fly-by-wire aircraft. The DARE system contains a state-of-the-art flight computer system and receiving equipment that permits use of the NASA/Wallops Flight Center's position-tracking ground-based display-generation and ground-to-air digital-data-link equipment. The DARE/ARA system will be used for flight evaluation of advanced control, guidance, and display concepts developed as part of NASA/Langley Research Center's general aviation terminal area operations program.

Downing, D. R.↗
NASA NTRS1979

Satellite-sensed winter nocturnal temperature patterns of the Everglades Agricultural Area

Surface temperature patterns of drained organic soil farmland in the Everglades Agricultural Area south of Lake Okeechobee, Florida, were studied using GOES-1 satellite infrared digital data for the winters of 1976-77 and 1977-78. Local thermal features were explained in terms of soil types, soil depths and climate modification caused by organic soil drainage. A cold-prone area was delineated in the Everglades Agricultural Area with satellite data. The winter nighttime surface temperatures of this area were more characteristic of north central Florida, approximately 370 km further north, than of surrounding areas of mineral soil or undrained organic soil.

Chen, E.↗
NASA NTRS1981

28-Channel rotary transformer

Transformer transmits power and digital data across rotating interface. Array has many parallel data channels, each with potential l megabaud data rate. Ferrite-cored transformers are spaced along rotor; airgap between them reduces crosstalk.

Mclyman, W. T.↗
NASA NTRS1980

Graphics and composite material computer program enhancements for SPAR

User documentation is provided for additional computer programs developed for use in conjunction with SPAR. These programs plot digital data, simplify input for composite material section properties, and compute lamina stresses and strains. Sample problems are presented including execution procedures, program input, and graphical output.

Farley, G. L.↗
NASA NTRS1979

LANDSAT digital analysis of the initial recovery of the Kokolik River tundra fire area, Alaska

The author has identified the following significant results. Considerable regrowth of vegetation was observed between August 1977 and August 1978, both in the field and through analysis of LANDSAT near infrared digital data. The spectral reflectances in the burned areas were found to increase with the age of the burn in a one year period due to vegetation regrowth. Regrowth was particularly evident in the lightly burned portions of the burned area. Image analysis techniques using the AOIPS system permitted delineation of burn severity categories. The conditions and type of ground cover prior to the fire influenced the severity of burning, as did the direction of the winds while the burning was in progress as determined from field and LANDSAT observations. More severe burning was induced by winds blowing in the northeastern and southeastern portions of the burned area.

Hall, D. K.↗