This paper presents a non-linear filtering method based on the multiresolution analysis of the Discrete Wavelet Transform (DWT). The main idea is to use the time-frequency localization properties of the wavelet decomposition. The proposed algorithm is using an extra decomposition of the identified noise in order to reduce the correlation between the electrocardiogram (ECG) signal and noise. The...

We have developed a new expansion’ we call the “chirplet transform”. It has been successfully applied to a wide variety of signal processing applications including radar[l] and image processing. There has been a recent debate as to the relative merits of an affine-in-time (wavelet) transform and the classical Short Time Fourier Transform (STFT), for the analysis of non-stationary phenomena. Chi...

Defects inside insulation of HV XLPE cable accessories can lead to partial discharge (PD) activity. When PD activity happens, leakage current may flow through the grounded line. To acquire the PD current signal, one practicable and effective method is placing a high frequency current transformer (HFCT) winding the grounded line. In order to measure the insulation degradation, a partial discharg...

Abstrac t This paper presents a method for locating and measuring the size of cracks in beams by time of flight (ToF) of ultrasonic wave. The echo detected was processed using the stationary wavelet transform and the Hilbert transform. The accuracy of the information obtained from the processed signal depends on the selected mother wavelet. To select the best mother wavelet for signal processin...

The roller bearing characteristic frequencies contain very little energy, and are usually overwhelmed by noise and higher levels of structural vibrations. Therefore, envelope spectrum analysis is widely used to detection bearing localized fault. In order to overcome the shortcomings in the traditional envelope analysis in which manually specifying a resonant frequency band is required, a new ap...

Wavelets are of wide potential use in statistical contexts. The basics of the discrete wavelet transform are reviewed using a lter notation that is useful subsequently in the paper. A `stationary wavelet transform', where the coeecient sequences are not decimated at each stage, is described. Two diierent approaches to the construction of an inverse of the stationary wavelet transform are set ou...

Wavelet transforms are not capable of reconstructing curved images perfectly, hence we go for this new concept, called Contourlet Transform. It is a multiresolution and directional decomposition of a signal using a combination of Laplacian Pyramid (LP) and a Directional Filter Bank (DFB). The Contourlet transform has good approximation properties for smooth 2D functions and finds a direct discr...

One of the most promising non-invasive markers of the activity of the autonomic nervous system is Heart Rate Variability (HRV). HRV analysis toolkits often provide spectral analysis techniques using the Fourier transform, which assumes that the heart rate series is stationary. To overcome this issue, the Short Time Fourier Transform is often used (STFT). However, the wavelet transform is though...

in this paper we present a method to perform flood frequency analysis (ffa) when the assumption of stationary is not important (or not valid). a wavelet transform model is developed to ffa. a full series is applied to ffa using two different wavelet functions, and then a combined method is investigated. in the combined method, all discharge data which were less than the lowest value of annual m...