spectral decomposition is a powerful tool for analysis of seismic data. fourier transform determines the frequency contents of a signal. but for analysis of non-stationary signals, 1-d transform to frequency domain is not sufficient. in early years, transforming of seismic traces into time and frequency domain was done via windowed fourier transform, called a short time fourier transform (stft)...

Introduction Conclusions References

The main limitation in employing orthogonal frequency division multiplexing (OFDM) system is high peak-toaverage power ratio (PAPR) of the transmitted signal. A new nonlinear companding algorithm that transforms the OFDM signals into the desirable statistics form defined by a linear piecewise function is proposed. The more adjustability in companding form and an effective trade-off between the ...

A new signal-adaptive joint time-frequency distribution for the analysis of nonstationary signals is proposed. It is based on a fractionalFourier-domain realization of the weighted Wigner distribution producing auto-terms close to the ones in the Wigner distribution itself, but with reduced cross-terms. Improvement over the standard time-frequency representations is achieved when the principal ...

We prove a new theorem about the relationship between optical field Wigner function’s Radon transform and optical Fresnel transform of the field, i.e., when an input field ψ (x′) propagates through an optical [D (−B) (−C)A] system, the energy density of the output field is equal to the Radon transform of the Wigner function of the input field, where the Radon transform parameters are D,B. We pr...

flood risk zonation is necessary to control and predict the amplitude of flood damage.the purpose of this research is to evaluate the rate of flood risk vulnerability and the flood damage assessment in tabriz. specific variables of this study are land use , population density , river beds , slope classes residential density , cn coefficient , runoff coefficient , open spaces and old buildings.m...

Flood Frequency Analysis is usually based on the fitting of an extreme value distribution to the series of local streamflow. However, when the local data series is short, frequency analysis results become unreliable. Regional frequency analysis is a convenient way to reduce the estimation uncertainty. In this work, we propose a regional Bayesian model for short record length sites. This model i...

abstract natural disasters threatening and endangering human communities has resulted in the study and research of such disasters through the related sciences and present methods of forecasting their behavior with time and place and also from a qualification and quantity viewpoint. to this end, numerous methods for the determination of the maximum flood in various return period has been made av...