Seismic Design and Analysis of Structures
نویسنده
چکیده
The problem of estimating the power spectra of non-stationary stochastic processes by using the harmonic wavelet transform is addressed in this paper. Conventional spectral analysis provides spectral coefficients that are averaged over time and thus, does not represent the evolutionary behavior of power spectra of non-stationary processes. In this study, evolutionary power spectrum of a non-stationary process is expressed in terms of its wavelet coefficients. Harmonic wavelets are chosen due to the appealing properties of the harmonic basis functions; the non-overlapping frequency feature of harmonic wavelets belonging to adjacent scales facilitates the spectral estimation task. The performance of dyadic, generalized and filtered Harmonic wavelets are compared by calculating the instantaneous mean square values of signals compatible with a given spectrum. It has been found that the filtered wavelet spectrum gives the best estimate for the power spectrum. The usefulness of the proposed method is demonstrated by estimating the evolutionary ground spectra of the Kocaeli, Turkey earthquake (08/17/1999).
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