1,745 research outputs found

    Investigation of several aspects of LANDSAT 4/5 data quality

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    A technique under development uses a zoom transfer scope to register the photograph of the target with digitally enlarged photographic hardcopy of the TM data using a visual fit to the area surrounding the target. The first attempt using the Sacramento Scene (44/33) of February 1, 1983 indicated that relief displacement in the aerial photography would cause large errors. A second attempt is in progress using the aero-triangulated scene centers which have no relief displacement. Being calculated points, the scene centers have somewhat larger absolute errors in geolocation, approximately 3 meters instead of 1.5 meters. The average TM effective instantaneous field of view (EIFOV) calculated from modulation transfer functions (MTFs) is 52.7 m. This is smaller than the 55 and 65 m EIFOVs reported earlier using noisy MTFs but larger than the EIFOVs from the San Mateo Bridge analysis which ranged from 44.5 to 50.9 m and averaged 47.6 m for the same TM scene

    Investigation of several aspects of LANDSAT-4 data quality

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    The Thematic Mapper scene of Sacramento, CA acquired during the TDRSS test was received in TIPS format. Quadrants for both scenes were tested for band-to-band registration using reimplemented block correlation techniques. Summary statistics for band-to-band registrations of TM band combinations for Quadrant 4 of the NE Arkansas scene in TIPS format are tabulated as well as those for Quadrant 1 of the Sacramento scene. The system MTF analysis for the San Francisco scene is completed. The thermal band did not have sufficient contrast for the targets used and was not analyzed

    Impact of LANDSAT MSS sensor differences on change detection analysis

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    Some 512 by 512 pixel subwindows for simultaneously acquired scene pairs obtained by LANDSAT 2,3 and 4 multispectral band scanners were coregistered using LANDSAT 4 scenes as the base to which the other images were registered. Scattergrams between the coregistered scenes (a form of contingency analysis) were used to radiometrically compare data from the various sensors. Mode values were derived and used to visually fit a linear regression. Root mean square errors of the registration varied between .1 and 1.5 pixels. There appear to be no major problem preventing the use of LANDSAT 4 MSS with previous MSS sensors for change detection, provided the noise interference can be removed or minimized. Data normalizations for change detection should be based on the data rather than solely on calibration information. This allows simultaneous normalization of the atmosphere as well as the radiometry

    AIS Investigation of Agricultural Monocultures

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    Airborne Imaging Spectrometer (AIS) data were acquired over an agricultural area in eastern San Joaquin County, California in July, 1984. Cover type information was subsequently collected for all fields along this flight line. The lack of detailed ground data on individual fields, however, limited AIS data analysis to a qualitative comparison of the spectral reflectance curves for a total of nine cover types. Based on this analysis, it appears that cover types with a positive slope in the 1550 to 1700 nm region have a higher spectral response in the 1200 to 1300 nm region compared to those cover types with a negative slope in the 1550 to 1700 nm region. Within cover type, spectral variability was also found to be greater than that between cover types. Given the lack of additional field data, the reason for these differences is a matter of speculation

    Development of a high efficiency thin silicon solar cell

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    A key to the success of this program was the breakthrough development of a technology for producing ultra-thin silicon slices which are very flexible, resilient, and tolerant of moderate handling abuse. Experimental topics investigated were thinning technology, gaseous junction diffusion, aluminum back alloying, internal reflectance, tantalum oxide anti-reflective coating optimization, slice flexibility, handling techniques, production rate limiting steps, low temperature behavior, and radiation tolerance

    Development of a high efficiency thin silicon solar cell

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    Significant improvements in open-circuit voltage and conversion efficiency, even on relatively high bulk resistivity silicon, were achieved by using a screen-printed aluminum paste back surface field. A 4 sq cm 50 micron m thick cell was fabricated from textured 10 omega-cm silicon which had an open-circuit voltage of 595 mV and AMO conversion efficiency at 25 C of 14.3%. The best 4 sq cm 50 micron thick cell (2 omega-cm silicon) produced had an open-circuit voltage of 607 mV and an AMO conversion efficiency of 15%. Processing modifications are described which resulted in better front contact integrity and reduced breakage. These modifications were utilized in the thin cell pilot line to fabricate 4 sq cm cells with an average AMO conversion efficiency at 25 C of better than 12.5% and with lot yields as great as 51% of starts; a production rate of 10,000 cells per month was demonstrated. A pilot line was operated which produced large area (25 cm) ultra-thin cells with an average AMO conversion efficiency at 25 deg of better than 11.5% and a lot yield as high as 17%

    Process Research on Polycrystalline Silicon Material (PROPSM)

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    Results of hydrogen-passivated polycrysalline silicon solar cell research are summarized. The short-circuit current of solar cells fabricated from large-grain cast polycrystalline silicon is nearly equivalent to that of single-crystal cells, which indicates long bulk minority-carrier diffusion length. Treatments with molecular hydrogen showed no effect on large-grain cast polycrystalline silicon solar cells

    Process Research on Polycrystalline Silicon Material (PROPSM)

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    Results of hydrogen-passivated polycrystalline silicon solar cells are summarized. Very small grain or short minority-carrier diffusion length silicon was used. Hydrogenated solar cells fabricated from this material appear to have effective minority-carrier diffusion lengths that are still not very long, as shown by the open-circuit voltages of passivated cells that are still significantly less than those of single-crystal solar cells. The short-circuit current of solar cells fabricated from large-grain cast polycrystalline silicon is nearly equivalent to that of single-crystal cells, which indicates long bulk minority-carrier diffusion length. However, the open-circuit voltage, which is sensitive to grain boundary recombination, is sometimes 20 to 40 mV less. The goal was to minimize variations in open-circuit voltage and fill-factor caused by defects by passivating these defects using a hydrogenation process. Treatments with molecular hydrogen showed no effect on large-grain cast polycrystaline silicon solar cells

    Women Becoming Bosses: Changing Gender Roles and Decision Making in Dangme West District of Ghana

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    Using both quantitative and qualitative data from the Dangme West district of Ghana, this study shows how the changing socio-economic status of women, as a result of governmental and non-governmental interventions, has influenced women to economically contribute more in their homes, become less vulnerable and subsequently improve their decision-making roles. The study also revealed that other factors such as unemployment and out-migration of men are creating more space for women to assume 'headship' positions and act as major decision-makers in the home. This 'new' gender role and position of women is, however, creating gender antagonism at the household level. The study recommends that NGOs and government agencies must strategically tackle the complexities of decisionmaking and bmgaining power in interpersonal relationships. Moreover, sensitive issues concerning sexual behaviour must be addressed as the first step towards any intervention. Key words: Ghana, Dangme West, decision making, gender, gender role

    Factors Affecting Quality and Location Values for Resident Deer Hunting in Utah

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    Application was made of the economic rent method of resource valuation for the resident deer hunt in Utah. Total economic, location and quality rent values were estimated for all hunting units. These values incorporate the relationship existing between the variable use cost and the units of activity associated with the site. Data were collected by mail survey from hunters following the 1970 season. Approximately 2033 questionnaires were used in the analysis. Additional data were collected from the Utah Division of Natural Resources. The total rent value estimated from the model was approximately $3,326,238.00. Eighty-five percent of the total was attributed to quality and 15 percent to location. Total rent values were highest for Unit 2 (Cache, Unit l (Box Elder) and Unit 6 (Lost Creek). It was hypothesized that variations in quality value could be explained by variations in site specific factors. The factors were made subject to multiple regression analysis and the number of bucks, two and one-half years of age and greater taken by resident hunters, was found to be the most significant. Variation in this variable and the others in the model explained 71.3 percent of the variation in the site quality value. To test the sensitivity of capacity in the model, an additional set of capacity constraints were estimated and used in the least-cost program. This gave a higher least cost allocation as the hunters were forced to incur a higher transfer cost. In this allocation the location value increased as the quality value decreased. Multiple regression analysis indicated that 83.3 percent of the variation in site quality was due to variations in site specific factors
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