29,637 research outputs found

    Liquid Rocket Engine Turbopump Rotating-shaft Seals

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    A monograph is organized and presents, for effective use in design, the significant experience and knowledge accumulated in development and operational programs to date. It reviews and assesses current practices, and from them establishes firm guidance for achieving greater consistency in design, increased reliability in the end product, and greater efficiency in the design effort. The monograph is divided into two major sections: state of the art and design criteria

    Evaluation of existing knowledge of the tectonic history and lithospheric structure of South America

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    While data is available on the lithospheric and crustal structure of the Andes region of South America, there is limited knowledge of these aspects of the eastern portion of the continent. For this reason, a surface wave dispersion study of the area was initiated. Long period seismograms were obtained for a tripartite analysis of dispersion. A flow chart of the analysis to be conducted is presented along with a preliminary geologic/tectonic map that was prepared. Efforts to characterize the provinces identified in terms of their geological and geophysical parameters continue

    The crustal structure and tectonics of South America

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    A preliminary crustal structure map and a bibliography of crustal and upper mantle studies for South America are given. Work on the surface wave analysis and tectonic characterizations continues

    Application of MAGSAT to lithospheric modeling in South America

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    Progress in the determination of relations of MAGSAT anomalies to lithospheric structures is reported. The prime emphasis was on a Rayleigh wave study and the determination of both group and phase velocity dispersion

    Crustal and upper mantle structure data analysis

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    Approximately 50 seismograms obtained from the National Geophysical and Solar-Terrestrial Data Center were digitized and analysis of surface wave dispersion was begun

    A composition theorem for the Fourier Entropy-Influence conjecture

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    The Fourier Entropy-Influence (FEI) conjecture of Friedgut and Kalai [FK96] seeks to relate two fundamental measures of Boolean function complexity: it states that H[f]≤CInf[f]H[f] \leq C Inf[f] holds for every Boolean function ff, where H[f]H[f] denotes the spectral entropy of ff, Inf[f]Inf[f] is its total influence, and C>0C > 0 is a universal constant. Despite significant interest in the conjecture it has only been shown to hold for a few classes of Boolean functions. Our main result is a composition theorem for the FEI conjecture. We show that if g1,...,gkg_1,...,g_k are functions over disjoint sets of variables satisfying the conjecture, and if the Fourier transform of FF taken with respect to the product distribution with biases E[g1],...,E[gk]E[g_1],...,E[g_k] satisfies the conjecture, then their composition F(g1(x1),...,gk(xk))F(g_1(x^1),...,g_k(x^k)) satisfies the conjecture. As an application we show that the FEI conjecture holds for read-once formulas over arbitrary gates of bounded arity, extending a recent result [OWZ11] which proved it for read-once decision trees. Our techniques also yield an explicit function with the largest known ratio of C≥6.278C \geq 6.278 between H[f]H[f] and Inf[f]Inf[f], improving on the previous lower bound of 4.615

    Focal plane transport assembly for the HEAO-B X-ray telescope

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    The High Energy Astronomy Observatory - Mission B (HEAO-B), an earth orbiting X-ray telescope facility capable of locating and imaging celestial X-ray sources within one second of arc in the celestial sphere, is considered. The Focal Plane Transport Assembly (FPTA) is one of the basic structural elements of the three thousand pound HEAO-B experiment payload. The FPTA is a multifunctional assembly which supports seven imaging X-ray detectors circumferentially about a central shaft and accurately positions any particular one into the focus of a high resolution mirror assembly. A drive system, position sensor, rotary coupler, and detent alignment system, all an integral part of the rotatable portion which in turn is supported by main bearings to the stationary focal plane housing are described

    Bosch CO2 Reduction System Development

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    Development of a Bosch process CO2 reduction unit was continued, and, by means of hardware modifications, the performance was substantially improved. Benefits of the hardware upgrading were demonstrated by extensive unit operation and data acquisition in the laboratory. This work was accomplished on a cold seal configuration of the Bosch unit

    A carbon dioxide reduction unit using Bosch reaction and expendable catalyst cartridges

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    Catalytic carbon dioxide reduction cartridge for oxygen recovery in life support systems of long term manned space flight

    Solid rocket motor internal insulation

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    Internal insulation in a solid rocket motor is defined as a layer of heat barrier material placed between the internal surface of the case propellant. The primary purpose is to prevent the case from reaching temperatures that endanger its structural integrity. Secondary functions of the insulation are listed and guidelines for avoiding critical problems in the development of internal insulation for rocket motors are presented
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