6,667 research outputs found
Stirling Module Development Overview
The solar parabolic dish Stirling engine electrically generating module consists of a solar collector coupled to a Stirling engine powered electrical generator. The module is designed to convert solar power to electrical power in parallel with numerous identical units coupled to an electrical utility power grid. The power conversion assembly generates up to 25 kilowatts at 480 volts potential/3 phase/alternating current. Piston rings and seals with gas leakage have not occurred, however, operator failures resulted in two burnt out receivers, while material fatigue resulted in a broken piston rod between the piston rod seal and cap seal
Satellite Power System (SPS) environmental impacts, preliminary assessment
Present power plant assessment factors are used to present satellite power system (SPS) impacts. In contrast to oil, gas, nuclear and coal fueled power plants, the SPS and hydroelectric power plants produce air, water, and solid waste emissions only during the construction phase. Land use impacts result from the placement of rectennas used for microwave receiving and rectifying. Air quality impacts of the SPS resulting from the construction phase amount to 0.405 metric tons per megawatt year. Solid wastes impacts are 0.108 metric tons per year of operation. Other impacts such as those caused by heavy lift launch vehicle sites are also discussed
Brain mechanisms in conditioning and learning
Brain mechanisms in conditioning and learning of higher mammal
Experimentally measured effects of the wall boundary layer on shock-tube performance
Nitrogen driven gas wall boundary layer effect and hydrogen driver gas thermodynamic effect on shock speed and test time in tub
Electron spin resonance study of thermal instability reactions in jet fuels
Free radicals were studied by electron spin resonance (ESR) using model compounds that are representative of constituents of jet fuels. Radical formation was initiated with peroxides and hydroperoxides by using UV photolysis at and near room temperature and thermal initiation at higher temperatures. Both oxygen free and air saturated systems were studied. N-Dodecane was frequently used as a solvent, and a mixture of n-dodecyl radicals was made with a peroxide initiator in n-dodecane (free of oxygen) thermally at 212 C and photolytically at room temperature. Hydrogen abstraction from the 3,4,5 and 6-positions gives radicals that are sufficiently alike that their spectra are essentially superimposed. The radical formed by abstract of hydrogen from the 2-position gives a different spectrum. ESR parameters for these radicals were measured. The radical formed by abstraction of a primary hydrogen was not observed. Similar radicals are formed from n-decane. A variety of exploratory experiments were carried out with systems that give free radical spectra to which was added small amounts of 2,5-dimethylpyrrole
Research on computational and display requirements for human control of space vehicle boosters. Part 1 - Theory and results Final report, 22 Jun. - 22 Oct. 1966
Computational and display requirements for man-computer guidance and control techniques for reusable manned spacecraf
Observed variability in the Fraunhofer line spectrum of solar flux, 1975 - 1980
Over the five years double-pass spectrometer observations of the Sun-as-a-star revealed significant changes in line intensities. The photospheric component weakened linearly with time 0 to 2.3%. From a lack of correlation between these line weakenings and solar activity indicators like sunspots and plage, a global variation of surface properties is inferred. Model-atmosphere analysis suggests a slight reduction in the lower-photospheric temperature gradient corresponding to a 15% increase in the mixing length within the granulation layer. Chromospheric lines such as Ca II H and K, Ca II 8543 and the CN band head weaken synchronously with solar activity. Thus, the behavior of photospheric and chromospheric lines is markedly different, with the possibility of secular change for the former
Failing GeorgiaThe Case Against the Ban on Social Promotion
Our analysis begins with an examination of the state of Georgia's rationale for the decision regarding social promotion that was based on the perceived views that teachers have on the issue. Research suggests, however, that teachers hold contradictory opinions concerning the use of standardized tests for high stakes decisions, such as promotion, and are not aware of the consequences most children suffer when they fail a grade. Following a discussion that challenges the claims of success in Chicago, Baltimore, and Texas, we explore the viability of choosing litigation as a strategy to stop the use of high stakes tests given the adverse impact they have on protected minorities. From a study of the thirty-nine poorest counties in rural Georgia, the relationships between poverty, race and the Georgia Criterion Referenced Competency Test Results suggest that these tests do have an enormously disparate impact on impoverished African American children. Because chances for educational attainment will be severely limited by this test, most African American children will be discouraged from achieving a high school diploma. As a way to put a face on the data, a case study of a young girl who would probably fail her grade in school if the law was enforced is presented followed by recommendations that argue for changes in education policy and teaching. Rather than mandate a ban on social promotion, the state of Georgia should pursue improvement of socio-economic conditions, education policy and pedagogy
Dynamic Formation of Metastable Intermediate State Patterns in Type-I Superconductors
Structure of the intermediate state in type-I superconducting lead (Pb) is
shown to be very sensitive to the ramp rate of an applied magnetic field. The
configurations of resulting static patterns depend sensitively on the shape of
the specimen. In particular, geometric barrier, present in the samples with
rectangular cross-section, plays an important role in determining the sharp
boundary between the phases of different topology. We propose that seemingly
laminar (stripe) pattern obtained as a result of the fast field ramp is simply
an imprint left behind by the fast-moving flux tubes. Our results confirm that
flux tube phase is topologically favorable.Comment: to be presented at LT-25 (Amsterdam, 2008
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