274 research outputs found

    Homogenization of the one-dimensional wave equation

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    We present a method for two-scale model derivation of the periodic homogenization of the one-dimensional wave equation in a bounded domain. It allows for analyzing the oscillations occurring on both microscopic and macroscopic scales. The novelty reported here is on the asymptotic behavior of high frequency waves and especially on the boundary conditions of the homogenized equation. Numerical simulations are reported

    Hydrogen ICE Vehicle Testing Activities

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    The Advanced Vehicle Testing Activity teamed with Electric Transportation Applications and Arizona Public Service to develop and monitor the operations of the APS Alternative Fuel (Hydrogen) Pilot Plant. The Pilot Plant provides 100% hydrogen, and hydrogen and compressed natural gas (H/CNG)-blended fuels for the evaluation of hydrogen and H/CNG internal combustion engine (ICE) vehicles in controlled and fleet testing environments. Since June 2002, twenty hydrogen and H/CNG vehicles have accumulated 300,000 test miles and 5,700 fueling events. The AVTA is part of the Department of Energy’s FreedomCAR and Vehicle Technologies Program. These testing activities are managed by the Idaho National Laboratory. This paper discusses the Pilot Plant design and monitoring, and hydrogen ICE vehicle testing methods and results

    A second order minimality condition for the Mumford-Shah functional

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    A new necessary minimality condition for the Mumford-Shah functional is derived by means of second order variations. It is expressed in terms of a sign condition for a nonlocal quadratic form on H01(Γ)H^1_0(\Gamma), Γ\Gamma being a submanifold of the regular part of the discontinuity set of the critical point. Two equivalent formulations are provided: one in terms of the first eigenvalue of a suitable compact operator, the other involving a sort of nonlocal capacity of Γ\Gamma. A sufficient condition for minimality is also deduced. Finally, an explicit example is discussed, where a complete characterization of the domains where the second variation is nonnegative can be given.Comment: 30 page
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