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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 271 records · Page 15

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NASA NTRS1981

Estimation of irrigated land using Landsat digital data

Techniques developed by the University of California and NASA for the utilization of multitemporal Landsat digital data in estimating and mapping irrigated land are presented. Three dates of Landsat were registered to each other and to a USGS 7.5 minute quadrangle map base for approximately 1.9 million acres of land. Other data registered include county boundaries, land use stratification, and digitized ground data. To identify irrigated land, an indicator was used which consisted of the ratio of MSS Band 7 to MSS Band 5 (the 7/5 ratio). A threshold 7/5 irrigated land value was determined for each date, as actively growing land generally has a higher 7/5 ratio than other cover classes. An estimate of irrigated land was determined by Landsat classification with ground data, at a relative standard error of + or - 7.98% at the 95% confidence interval. Mapping evaluation reveals a 94% accuracy, a 7.4% omission rate, and a 6.3% commission rate. In addition, a sample unit size evaluation recommends a 1-1 1/2 square mile sample range.

Brown, C. E.↗

NASA NTRS1982

Sacremento Municipal Utility District 100-MW sub e photovoltaic plant

A status report on plans for the Sacramento Municipal Utility District (SMUD) 1-MW photovoltaic power plant is presented. DOE, the California Energy Commission, and SMUD will fund the project cooperatively. Emphasis is placed on the details of the government contract/cooperation agreement.

Powell, R. V.↗

NASA NTRS1982

Vibration and destabilizing effects of floating ring seals in compressors

Operating experience on a compressor commissioned 12 years ago has presented an interesting history of sporadic increases in shaft vibration. Initial operation was satisfactory with low levels of vibration. However, after some time the shaft vibration level increased to several mils. Initially this was believed to be due to rotor unbalance from deposits formed in the passages due to process upsets. After cleaning up the rotor, operation was again increased. It was then found that the rotor vibration was primarily subsynchronous. Further investigation revealed that the original seal design was subject to wear and was no longer properly pressure balanced. A modified seal design was installed and it has operated successfully for the past six years.

Emerick, M. F.↗

NASA NTRS1981

LANDSAT landcover information applied to regional planning decisions

Land cover information derived from LANDSAT is being utilized by Piedmont Planning District Commission located in the State of Virginia. Progress to date is reported on a level one land cover classification map being produced with nine categories. The nine categories of classification are defined. The computer compatible tape selection is presented. Two unsupervised classifications were done, with 50 and 70 classes respectively. Twenty-eight spectral classes were developed using the supervised technique, employing actual ground truth training sites. The accuracy of the unsupervised classifications are estimated through comparison with local county statistics and with an actual pixel count of LANDSAT information compared to ground truth.

Dixon, C. M.↗

NASA NTRS1981

Area estimation of forestlands in southwestern Michigan from LANDSAT imagery

The accuracy of mapping and estimating the area of forestlands in southwestern Michigan from winter and fall LANDSAT images was evaluated. All omission and commission errors in the LANDSAT forest maps were identified and mapped through comparison with an existing detailed forest cover type map. Accuracies ranged from 74.0% to 98.5% and were higher for the winter imagery. Most errors (85%) occurred along the perimeter of forestlands and were less than 4 hectares (10 acres) and size. Other factors affecting interpretation are reported as well as time and image availability considerations.

Karteris, M. A.↗

NASA NTRS1982

Energy Facility Siting by Means of Environmental Modelling with LANDSAT, Thematic Mapper and Geographic Information System (GIS) Data

Currently based on ground and aerial surveys, the land cover data base of the Pennsylvania Power and Light Company is routinely used for modelling the effects of alternative generating plant and transmission line sites on the local and regional environment. The development of a satellite-based geographic information system would facilitate both the preparation of environmental impact statements by power companies and assessment of the data by the Nuclear Regulatory Commission. A cooperative project is planned to demonstrate the methodology for integrating satellite data into an existing geographic information system, d to further evaluate the ability of satellite data in modeling environmental conditions that would be applied in the preparation and assessment of environmental impact statements.

Source record↗

NASA NTRS1982

Integration of Fish and Wildlife Data with Geobased and Remotely Sensed Land Use/land Cover Data: a Demonstration Using Sites in Pennsylvania

The U.S. Fish and Wildlife Service developed a statewide fish and wildlife data base for the Pennsylvania Game Commission that includes 125 categories of information on each of the 844 species. This species data base is integrated with geobased and remotely-sensed land use/land cover data from two sites in Pennsylvania. One site is an energy development project; the other is a high-energy use area. Analyses using the combined animal and land use data bases can be demonstrated for a variety of land use/land cover types at both sites. The ability to make "what if" analysis prior to project implementation is presented.

Cushwa, C. T.↗

NASA NTRS1984

Relative Accuracy Assessment of LANDSAT-4 MSS and TM Data for Level 1 Land Cover Inventory

Digital data for the Washington, D.C. scene from the LANDSAT-4 Multispectral Scanner (MSS) and the LANDSAT-4 Thematic Mapper (TM) are compared. Classification success for the TM and MSS data sets was determined by a per pixel comparison with digitized ground verification data (GVD). These GVD were comprised of Level I land cover (developed, agriculture, forest, water, wetlands, and barren) for four USGS 7.5-minute topographic quadrangle maps. Classification accuracy was computed as an average value and for each cover type. Accuracy was expressed two ways: (1) as the percent correspondence with GVD (% correct) and (2) as the percent correspondence relative to both the GVD and LANDSAT classification schemes. Errors of omission and commission associated with the LANDSAT classifications were also computed. Specific results are discussed.

Middleton, E. M.↗

NASA NTRS1983

A computerized, procedural aid for flight crews

A computer program for detecting pilot error is described. The program observes pilot actions through the aircraft controls and state, and the actions are compared to those of a procedural script which can be considered a prescriptive model of the procedural aspects of flight. Pilot error is a discrepancy between the pilot actions and the script. The script has a hierarchical structure consisting of a single script at the highest level, scripts for the major phases of flight at the next level, scripts for procedures to be executed during these phases, and procedure step scripts at the bottom. The program interprets the aircraft data base in terms of the script, detecting errors of commission from a set of allowed and disallowed changes stored with each script element.

Hammer, J. M.↗

NASA NTRS1985

Relative Accuracy Assessment of LANDSAT-4 MSS and TM Data for Level 1 Land Cover Inventory

Digital data for the Washington, DC scene simultaneously acquired by the LANDSAT-4 Multispectral Scanner (MSS) and the LANDSAT-4 thematic mapper (TM) was compared. Classification success for the TM and MSS data sets was determined by a per pixel comparison with digitized ground verification data (GVD). These GVD were comprised of Level 7 land cover (developed, agriculture, forest, water, wetlands, and barren) for four USGS 7.5 minute topographic quadrangle maps. The relative improvement in classification success for TM was between 11% and 14%, or about a factor of 1.3, for these data. This represents a meaningful improvement in accuracy for Level 7 land cover categorization for TM relative to MSS, particularly when errors of omission and commission were considered.

Middleton, E. M.↗

NASA NTRS1985

Damping seal verification setup

The heart of the Space Shuttle Main Engine (SSME) is a set of turbopumps that propel cryogenic fluids at very high pressures and flow rates, at rotor speeds up to 37,000 rpm. Bushing seals that cause the flow in the fluid film to become turbulent, by means of a multiplicity of pockets, were shown theoretically not only to inhibit subsynchronous whirl, but to reduce leakage as well. However, experimental data that relate these two desirable characteristics to such parameters as pocket depth, Reynolds number (based on clearance and axial flow rate), and rotating speed are limited. To obtain the required data, NASA's Marshall Space Flight Center (MSFC) commissioned Wyle Laboratories to design, build and operate a test rig in which the damping efficacy and leakage reduction of typical candidate seals are to be evaluated.

Cappel, K. L.↗

NASA NTRS1985

What color is the solar system?

Estimates are made of the true visual colors of various planets and moons in the solar system. Account is taken of the components of perceived color, i.e., hue, saturation and lightness. Earth is a blue planet while most of the others, including Mars, are yellow and differ only in their lightness. Widely disseminated Voyager images of Jupiter have been computer-enhanced to highlight details. A reflectance spectrum established by the International Commission on Illumination provides reference lines which are measured and compared with reference colors which would be seen on earth in normal daylight. Uranus is actually a light aqua color due to its absorption of 6190 A light and reflectance of 5000 A blue green light.

Young, A. T.↗

NASA NTRS1985

The northern Utah satellite (NUSAT) communications link

During the planning Stages of the NUSAT satellite, an obvious issue to be discussed was the method of communications to be used. The frequencies would have to be high enough to pass through the atmosphere relatively unattenuated but low enough that antennas and transmission lines would not be so critical in length and properties that unexperienced students would have difficulty with handling them. In conversations with the Federal Communications Commission (FCC) in Washington D.C., the frequencies of 450.000 MHz and 137.900 MHz were decided upon and applied for licensing. The 450.000 MHt up-link is used on a "non-interference" basis to control the satellite while the 137.900 MHz frequency down-links data from the satellite. A reasonable amount of time was spent discussing the mods of transmission to be used in communication with the satellite. Representatives of the amateur radio satellite organization, AMSAT, were contacted for ides. This organization seems to favor AM types of emissions such as CW to control their OSCAR series of satellites and also the current Phase 111 unit. NUSAT personnel felt, however, that there would be merit in the improved signal to noise ratio usually obtained in an FM mode. Doppler shift of the transmitted information on the NUSAT also had to be considered. The final decision WBS to use Audio Frequency Shift Keying (AFSK) modulated on an FM carrier. In this mode the audio tones used would not shift frequency with Doppler - only the carrier would shift in frequency. If necessary, the receivers could be fitted with a form of AFC control or simply have enough bandwidth to handle the Doppler shift with an acceptable increase in noise.

Lee Barrett↗

NASA NTRS1985

Development of AM 1.5 global measurement procedures and international cell measurement round robin

The development of the capability for measurement under global irradiance spectral distribution is reported. The airmass 1.5 global measurement procedure is given. Also given is the procedure and justification for using the large area pulsed solar simulator (LAPSS). The status of the international round robin of reference cell measurements managed by the Commission of European Communities (CEC) is described.

Mueller, R.↗

NASA NTRS1986

On the design of classifiers for crop inventories

Crop proportion estimators that use classifications of satellite data to correct, in an additive way, a given estimate acquired from ground observations are discussed. A linear version of these estimators is optimal, in terms of minimum variance, when the regression of the ground observations onto the satellite observations in linear. When this regression is not linear, but the reverse regression (satellite observations onto ground observations) is linear, the estimator is suboptimal but still has certain appealing variance properties. In this paper expressions are derived for those regressions which relate the intercepts and slopes to conditional classification probabilities. These expressions are then used to discuss the question of classifier designs that can lead to low-variance crop proportion estimates. Variance expressions for these estimates in terms of classifier omission and commission errors are also derived.

Heydorn, R. P.↗

NASA NTRS1986

National space transportation and support study/mission requirements and architecture studies

The government approach to fulfilling the requirements of the National Space Transportation and Support Study is described. DOD and NASA were required to determine the architecture and technology that would be needed for civil and defense space transportation during the 1995-2010 time range. NASA collected data from the National Commission on Space and the DOD research focused on SDI requirements. The objectives and recommendations of the space transportation architecture, transportation and support systems, and technology assessment and planning tasks are discussed.

Durocher, C. L.↗

NASA NTRS1986

Studies of asteroids and comets

About 3000 accurate positions of asteroids and comets were measured concentrating particularly on close-Earth approachers, but also targeting asteroids in need for follow-up observations because of unusual orbital characteristics or poor observational history. In 1985, 36 of the discoveries were numbered. Very accurate + or - 0.1 arcsec?) positional measurements were made of P/Halley on four nights in November and December 1985 in support of Giotto mission navigation. The asteroid orbit files were maintained, and ephemeris data for observational planning were supplied to colleagues worldwide. Considerable progress was made in understanding how information on asteroid shapes, surface albedo variegation, and rotational states can be derived from lightcurve and phase curve data. The analytical formulation was completed of a new asteroid magnitude system for the International Astronomical Union; the system was adopted at the New Delhi General Assembly by IAU Commission 20. Photographic photometry of about 10000 images of faint asteroids observed during the course of the United Kingdom Schmidt-CalTech Asteroid Survey in 1981 was continued, completing the microdensitometric scanning and all process of software development for data handling.

Bowell, E. L. G.↗

NASA NTRS1987

An investigation of transitional management problems for the NSTS

Analysis and recommendations were provided to the National Space Transportation System (NSTS) on managing the transition from a research and development (R/D) structure to an operational structure. Summaries of published literature on the theory and applications of transition, or change management, and the results of interviews with additional industry personnel whose organizations either have gone through or are now going through change are contained. The issues of flight rates and the flight decision are addressed. The use of a computer simulation model to analyze the effect of varying different parameters on the flight rate was also discussed. The issue of NASA's changing demographics was examined and why this may be a cause for concern. The impact of the whole shuttle system structure on the Challenger accident was presented along with the highlights of the Rogers Commission Report. The proposed reorganization of the NSTS management structure is discussed and how this transition from R/D to operations can be performed.

Hunsucker, John L.↗