warp and weft spacing and its coefficient of variation affect the physical properties of fabrics such as fabric hand, frictional and mechanical properties. in this paper the weft and warp spacing and its coefficient of variation for plain weave is calculated using fourier transforms. different methods have been used in this work including autocorrelation function. first, two dimensional power s...

Image Resolution enhancement (RE) schemes which are based on wavelets have an advantage over conventional methods which suffer from the losing of high frequency contents which causes blurring. The discrete wavelet transform-based (DWT) RE scheme generates artifacts due to a DWT shift-variant property. A wavelet-domain approach based on double density dual-tree complex wavelet transform (DDDT-CW...

The S transform is variable window of short time Fourier transform (STFT) or an extension of wavelet transform (WT). It is based on a scalable localizing Gaussian window and supplies the frequency dependent resolution. In this tutorial, we introduce the fundamental function of S transform and the generalized S transform. Furthermore, we present some applications of S transform: seismogram analy...

Harmonic wavelets have simple formulations in the fi-equency domain and they have proved a good basis for the time-frequency mapping of transient signals. Moreover their computational algorithm allows bandwidth to be chosen arbitrarily so that they offer a variable Q transform, where Q is the ratio of centre frequency to bandwidth. In contrast, the short-time Fourier transform and the Wlgner-Vi...

accurate estimate of flood flows at selected return periods is a fundamental step in flood control and design of hydraulic structures. due to the inadequacy or unavailability of flood flow records in several western catchments of iran, traditional regional flood frequency methods lead to remarkable estimate errors, particularly for long return periods. in this research, discriminant analysis is...

By use of window functions, time-frequency analysis tools like Short Time Fourier Transform overcome a shortcoming of the Fourier Transform and enable us to study the timefrequency characteristics of signals which exhibit transient oscillatory behavior. Since the resulting representations depend on the choice of the window functions, it is important to know how they influence the analyses. One ...

Ultrasound vibro-acoustography is a novel medical imaging modality that combines the high resolution of high-frequency ultrasound with the speckle-free images obtained using lowfrequency methods. This imaging modality relies on the nonlinear interaction of two high frequency beams at slightly different frequencies. We describe the physics of ultrasound vibroacoustography and outline a strategy ...

Wavelet analysis is a time – frequency analysis method, time-frequency localization problems are well solved, this paper analyzes the basic principles of the wavelet transform and the relationship between the signal singularity Lipschitz exponent and the local maxima of the wavelet transform coefficients mold, the principles of wavelet transform in image denoising are analyzed, the disadvantage...