27,487 research outputs found

    IR-transmission glasses formed from oxides of bismuth and tellurium

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    Bismuth trioxide-tellurium dioxide glasses have improved infrared transmission characteristics

    High dielectric thick films for screened circuit capacitors

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    Techniques and materials have recently been developed to obtain high dielectric films /K of 300 to 800/. High dielectric barium titanate particles are mixed in a barium titanate glass

    Aircraft-crash-locating transmitter features design improvements

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    Crash locater is automatically ejected from aircraft at time of crash and begins transmitting at emergency radio frequencies monitored by all airports and airport control towers. Advantages are smaller size, simpler design and installation, extended transmitting range and life, greater deployment reliability and increased crash resistance

    Planar leaky light-guides and couplers

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    A quantitative theory of light propagation in a dielectric slab guide with general cladding media is presented. It is based on a plane wave which bounces in a zigzag fashion along the guide as a result of total or partial reflections at the two surfaces of the film. Two mechanisms are considered which contribute to the attenuation of the guide: losses due to absorption in the slab and cladding materials, and radiation losses if the guide is a leaky one. We point out the significance of the Goos-Hänchen effect for all questions relating to the power flow in the slab guide. The theory is illustrated by discussing dispersion and attenuation of guides with various low-index and high-index claddings, operating above and below cutoff. The low-index leaky guide is considered particularly in detail. Its high attenuation by leakage can be reduced to practically acceptable values (<1d B/cm) by increasing the film thickness to ≳ 40λ. One application of this guide is in the leaky wave coupler. This coupler may be viewed as a prism-film coupler simplified by omission of the gap. It offers a new approach to the problem of broad-band coupling to thin-film light guides

    An analysis of the variation in wear life of hot pressed molybdenum disulfide-silver electrical contact brushes in vacuum

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    Wear life analysis of hot pressed molybdenum disulfide-silver electrical contact brushes in vacuu

    Socle degrees, Resolutions, and Frobenius powers

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    We first describe a situation in which every graded Betti number in the tail of the resolution of RJ\frac RJ may be read from the socle degrees of RJ\frac RJ. Then we apply the above result to the ideals JJ and J[q]J^{[q]}; and thereby describe a situation in which the graded Betti numbers in the tail of the resolution of R/J[q]R/J^{[q]} are equal to the graded Betti numbers in the tail of a shift of the resolution of R/JR/J.Comment: 19 page

    Geosynchrotron radio emission from CORSIKA-simulated air showers

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    Simulations of radio emission from extensive air showers we have published so far were performed with a Monte Carlo code using analytical parametrisations to describe the spatial, temporal, energy and angular particle distributions in the air shower. A new version of our simulation code, which replaces these parametrisations with precise, multi-dimensional histograms derived from per-shower CORSIKA simulations, is now available. The new code allows an independent selection between parametrisation and histogram for each of the relevant distributions, enabling us to study the changes arising from using a more realistic air shower model in detail. We describe the new simulation strategy, present some initial results and discuss the new possibilities.Comment: 6 pages, Proceedings of the ARENA2006 workshop, Newcastle, England; to be published in Journal of Physics: Conference Series (JPCS

    An inverse of the evaluation functional for typed Lambda-calculus

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    In any model of typed λ-calculus conianing some basic arithmetic, a functional p - * (procedure—* expression) will be defined which inverts the evaluation functional for typed X-terms, Combined with the evaluation functional, p-e yields an efficient normalization algorithm. The method is extended to X-calculi with constants and is used to normalize (the X-representations of) natural deduction proofs of (higher order) arithmetic. A consequence of theoretical interest is a strong completeness theorem for βη-reduction, generalizing results of Friedman [1] and Statman [31: If two Xterms have the same value in some model containing representations of the primitive recursive functions (of level 1) then they are provably equal in the βη- calculus
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