1,380 research outputs found

    Uniform asymptotics for the full moment conjecture of the Riemann zeta function

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    Conrey, Farmer, Keating, Rubinstein, and Snaith, recently conjectured formulas for the full asymptotics of the moments of LL-functions. In the case of the Riemann zeta function, their conjecture states that the 2k2k-th absolute moment of zeta on the critical line is asymptotically given by a certain 2k2k-fold residue integral. This residue integral can be expressed as a polynomial of degree k2k^2, whose coefficients are given in exact form by elaborate and complicated formulas. In this article, uniform asymptotics for roughly the first kk coefficients of the moment polynomial are derived. Numerical data to support our asymptotic formula are presented. An application to bounding the maximal size of the zeta function is considered.Comment: 53 pages, 1 figure, 2 table

    Probabilistic SSME blades structural response under random pulse loading

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    The purpose is to develop models of random impacts on a Space Shuttle Main Engine (SSME) turbopump blade and to predict the probabilistic structural response of the blade to these impacts. The random loading is caused by the impact of debris. The probabilistic structural response is characterized by distribution functions for stress and displacements as functions of the loading parameters which determine the random pulse model. These parameters include pulse arrival, amplitude, and location. The analysis can be extended to predict level crossing rates. This requires knowledge of the joint distribution of the response and its derivative. The model of random impacts chosen allows the pulse arrivals, pulse amplitudes, and pulse locations to be random. Specifically, the pulse arrivals are assumed to be governed by a Poisson process, which is characterized by a mean arrival rate. The pulse intensity is modelled as a normally distributed random variable with a zero mean chosen independently at each arrival. The standard deviation of the distribution is a measure of pulse intensity. Several different models were used for the pulse locations. For example, three points near the blade tip were chosen at which pulses were allowed to arrive with equal probability. Again, the locations were chosen independently at each arrival. The structural response was analyzed both by direct Monte Carlo simulation and by a semi-analytical method
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