During their service life, marine pipelines continually accumulate damage as a result of the action of various environmental forces. Clearly, the development of robust techniques for early damage detection is very important to avoid the possible occurrence of a disastrous structural failure. Most of vibration-based damage detection methods require the modal properties that are obtained from mea...

The problem of change detection of time series with abrupt and smooth changes in the spectral characteristics is addressed. We first review the main characteristics of the discrete wavelet transform and the maximal overlap discrete wavelet transform. An algorithm for sequential change detection in time series is then reported based on the maximal overlap discrete wavelet transform and Bayesian ...

The recursive algorithm of a (fast) discrete wavelet transform, as well as its generalizations, can be described as repeated applications of block-Toeplitz operators or, in the case of periodized wavelets, multiplications by block circulant matrices. Singular values of a block circulant matrix are the singular values of some matrix trigonometric series evaluated at certain points. The norm of a...

Analysis of circadian oscillations that exhibit variability in period or amplitude can be accomplished through wavelet transforms. Wavelet-based methods can also be used quite effectively to remove trend and noise from time series and to assess the strength of rhythms in different frequency bands, for example, ultradian versus circadian components in an activity record. In this article, we desc...

We present and discuss a method to identify substructures in combined angularredshift samples of galaxies within Clusters. The method relies on the use of Discrete Wavelet Transform (hereafter DWT) and has already been applied to the analysis of the Coma cluster (Gambera et al. 1997). The main new ingredient of our method with respect to previous studies lies in the fact that we make use of a 3...

Although FPGA technology offers the potential of designing high performance systems at low cost, its programming model is prohibitively low level. To allow a novice signal/image processing end-user to benefit from this kind of devices, the level of design abstraction needs to be raised. This approach will help the application developer to focus on signal/image processing algorithms rather than ...

In this paper we show that the dyadic wavelet transform may be generalized to include non-octave spaced frequency resolution. We introduce orthogonal and complete wavelets whose set of cutoff frequencies may be adapted, in the simplest case, by changing a single parameter. The novel wavelets and the FWWT transform computational structure are obtained via an intermediate Laguerre representation ...

In many applications it is desirable to study nonorthogonal wavelet transforms. A translation-invariant wavelet transform is a nonorthogonal variant of the classical wavelet transform which plays an important role in denoising algorithms. However, it has been observed in many experiments that the thresholding scheme for the orthogonal DWT should be slightly modiied for use in the translation-in...

Images require substantial storage and transmission resources, thus image compression is advantageous to reduce these requirements. The objective of this paper is to evaluate a set of wavelets for image compression. Image compression using wavelet transforms results in an improved compression ratio. Wavelet transformation is the technique that provides both spatial and frequency domain informat...

Wavelet Transforms are used in number of application. They are applied in different fields such as signal processing, speech and image compression, biometrics, and so on. One of its important applications is image compression. Wavelet Transforms are preferred over other transforms, to compress image, since reconstruction is more accurate. Design of discrete wavelet transforms is complex due to ...