1,380 research outputs found
Uniform asymptotics for the full moment conjecture of the Riemann zeta function
Conrey, Farmer, Keating, Rubinstein, and Snaith, recently conjectured
formulas for the full asymptotics of the moments of -functions. In the case
of the Riemann zeta function, their conjecture states that the -th absolute
moment of zeta on the critical line is asymptotically given by a certain
-fold residue integral. This residue integral can be expressed as a
polynomial of degree , whose coefficients are given in exact form by
elaborate and complicated formulas. In this article, uniform asymptotics for
roughly the first 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
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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