19,846 research outputs found
Satellite Power System. Concept development and evaluation program, volume 6: Construction and operations
The construction, operation, and maintenance requirements for a solar power satellite, including the space and ground systems, are reviewed. The basic construction guidelines are explained, and construction location options are discussed. The space construction tasks, equipment, and base configurations are discussed together with the operations required to place a solar power satellite in geosynchronous orbit. A rectenna construction technique is explained, and operation with the grid is defined. Maintenance requirements are summarized for the entire system. Key technology issues required for solar power satellite construction operations are defined
Velocity field near the jet orifice of a round jet in a crossflow
Experimentally determined velocities at selected locations near the jet orifice are presented and analyzed for a round jet in crossflow. Jet-to-crossflow velocity ratios of four and eight were studied experimentally for a round subsonic jet of air exhausting perpendicularly through a flat plate into a subsonic crosswind of the same temperature. Velocity measurements were made in cross sections to the jet plume located from one to four jet diameters from the orifice. Jet centerline and vortex properties are presented and utilized to extend the results of a previous study into the region close to the jet orifice
Seventh year projects and activities of the Environmental Remote Sensing Applications Laboratory (ERSAL)
There are no author-identified significant results in this report
Supermassive Black Hole Merger Rates: Uncertainties from Halo Merger Theory
The merger of two supermassive black holes is expected to produce a
gravitational-wave signal detectable by the satellite LISA. The rate of
supermassive-black-hole mergers is intimately connected to the halo merger
rate, and the extended Press-Schechter formalism is often employed when
calculating the rate at which these events will be observed by LISA. This
merger theory is flawed and provides two rates for the merging of the same pair
of haloes. We show that the two predictions for the LISA
supermassive-black-hole-merger event rate from extended Press-Schechter merger
theory are nearly equal because mergers between haloes of similar masses
dominate the event rate. An alternative merger rate may be obtained by
inverting the Smoluchowski coagulation equation to find the merger rate that
preserves the Press-Schechter halo abundance, but these rates are only
available for power-law power spectra. We compare the LISA event rates derived
from the extended Press-Schechter merger formalism to those derived from the
merger rates obtained from the coagulation equation and find that the extended
Press-Schechter LISA event rates are thirty percent higher for a power spectrum
spectral index that approximates the full Lambda-CDM result of the extended
Press-Schechter theory.Comment: 9 pages, 9 figures. More concise treatment, accepted for publication
in MNRA
Glaciological and volcanological studies in the Wrangell Mountains, Alaska
There are no author-identified significant results in this report
Vertical Equity in the Taxation of Single Family Homes
Vertical equity in ad valorem real property taxation is the concept that all properties within a taxing jurisdiction are assessed in equal proportion to their fair market value. This study examines the assessment of single family homes in Bellingham, Washington, utilizing a database of 1,118 home sales in the southern half of Bellingham that sold during the time period of January, 1990 through June, 1994. The results of several empirical tests suggest the presence of regressive vertical inequity. It appears that higher market value homes are assessed at a lower proportion of their value (sales price) than less expensive homes. These results suggest that property taxation at the local level magnifies the regessivity of Washington State's already highly regressive state tax system. Why does this apparent regressive vertical inequity exist? The authors offer several possibilities including the propensity of wealthy homeowners to challenge property tax assessments, the difficulty of valuing the amenities inside an upper-end home, the heterogeneity of the upper-end home market coupled with a small number of transactions, and the lack of ample staff and other resources at the County Assessor's office.
Methods development for total organic carbon accountability
This report describes the efforts completed during the contract period beginning November 1, 1990 and ending April 30, 1991. Samples of product hygiene and potable water from WRT 3A were supplied by NASA/MSFC prior to contract award on July 24, 1990. Humidity condensate samples were supplied on August 3, 1990. During the course of this contract chemical analyses were performed on these samples to qualitatively determine specific components comprising, the measured organic carbon concentration. In addition, these samples and known standard solutions were used to identify and develop methodology useful to future comprehensive characterization of similar samples. Standard analyses including pH, conductivity, and total organic carbon (TOC) were conducted. Colorimetric and enzyme linked assays for total protein, bile acid, B-hydroxybutyric acid, methylene blue active substances (MBAS), urea nitrogen, ammonia, and glucose were also performed. Gas chromatographic procedures for non-volatile fatty acids and EPA priority pollutants were also performed. Liquid chromatography was used to screen for non-volatile, water soluble compounds not amenable to GC techniques. Methods development efforts were initiated to separate and quantitate certain chemical classes not classically analyzed in water and wastewater samples. These included carbohydrates, organic acids, and amino acids. Finally, efforts were initiated to identify useful concentration techniques to enhance detection limits and recovery of non-volatile, water soluble compounds
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