Techniques with low hardware complexity of the driver electronics

Abstract— Demand for high‐quality images in mobile phones has set a new standard for displays in such portable devices. Active‐matrix liquid‐crystal displays (AMLCDs) are replacing passive‐matrix LCDs in these applications. One of the reasons is the lack of simple techniques for displaying a large number of gray shades. The goal was to develop new addressing techniques to fill this void, and it has been achieved without increasing the hardware complexity of the drive electronics. Various techniques that are capable of displaying a large number of gray shades with low hardware complexity of the driver circuit are reviewed.     

Series approximation of protein structure and constructing conformation space

Series approximations of the three-dimensional structure of protein conformations can provide insightful ways to detect and manipulate global features and those local to contiguous segments of the chain. Discrete cosine transforms have proven to be very useful in the past, and now wavelet transforms appear to have additional advantages. Here the emphasis is on a new generalization of the discrete Haar transform for chains of arbitrary length, as opposed to the customary powers of 2. This can be used to define a true, concrete conformation space, where different conformations correspond to points in the space, and a measure of distance between points corresponds to the customary root-mean-square deviation after optimal pairwise superposition (rmsd). Examples are given of how to do this to high accuracy. The key is to devise a rule for placing individual conformers in a standard position relative to the coordinate system, rather than superimposing them on a pairwise basis.     

Series approximation of protein structure and constructing conformation space

Series approximations of the three-dimensional structure of protein conformations can provide insightful ways to detect and manipulate global features and those local to contiguous segments of the chain. Discrete cosine transforms have proven to be very useful in the past, and now wavelet transforms appear to have additional advantages. Here the emphasis is on a new generalization of the discrete Haar transform for chains of arbitrary length, as opposed to the customary powers of 2. This can be used to define a true, concrete conformation space, where different conformations correspond to points in the space, and a measure of distance between points corresponds to the customary root-mean-square deviation after optimal pairwise superposition (rmsd). Examples are given of how to do this to high accuracy. The key is to devise a rule for placing individual conformers in a standard position relative to the coordinate system, rather than superimposing them on a pairwise basis.     

Fast solutions to physical equilibrium and interpolation problems

Efficient solutions to physical equilibrium and interpolation problems can be obtained by using wavelet basis vectors for problem discretization or for use as a preconditioning transform. Good approximations to these solutions can be obtained in onlyO(n) operations andO(n) storage locations, a property that can be extremely useful in visualization applications.     

Numerical discretization of stationary random processes

The increasing interest of the research community to the probabilistic analysis concerning the civil structures with space-variant properties points out the problem of achieving a reliable discretization of random processes (or random fields in a multi-dimensional domain). Given a discretization method, a continuous random process is approximated by a finite set of random variables. Its dimension affects significantly the accuracy of the approximation, in terms of the relevant properties of the continuous random process under investigation. The paper presents a discretization procedure based on the truncated Karhunen–Loève series expansion and the finite element method. The objective is to link in a rational way the number of random variables involved in the approximation to a quantitative measure of the discretization accuracy. The finite element method is applied to evaluate the terms of the series expansion when a closed form expression is not available. An iterative refinement of the finite element mesh is proposed in this paper, leading to an accurate random process discretization. The technique is tested with respect to the exponential covariance function, that enables a comparison with analytical expressions of the approximated properties of the random process. Then, the procedure is applied to the square exponential covariance functions, which is one of the most used covariance models in the structural engineering field. The comparison of the adaptive refinement of the discretization with a non-adaptive procedure and with the wavelet Galerkin approach allows to demonstrate the computational efficiency of the proposal within the framework of the Karhunen–Loève series expansion. A comparison with the Expansion Optimal Linear Estimation (EOLE) method is performed in terms of efficiency of the discretization strategy.     

A wavelet-based parameterization for speech/music discrimination

This paper addresses the problem of parameterization for speech/music discrimination. The current successful parameterization based on cepstral coefficients uses the Fourier transformation (FT), which is well adapted for stationary signals. In order to take into account the non-stationarity of music/speech signals, this work proposes to study wavelet-based signal decomposition instead of FT. Three wavelet families and several numbers of vanishing moments have been evaluated. Different types of energy, calculated for each frequency band obtained from wavelet decomposition, are studied. Static, dynamic and long-term parameters were evaluated. The proposed parameterization are integrated into two class/non-class classifiers: one for speech/non-speech, one for music/non-music. Different experiments on realistic corpora, including different styles of speech and music (Broadcast News, Entertainment, Scheirer), illustrate the performance of the proposed parameterization, especially for music/non-music discrimination. Our parameterization yielded a significant reduction of the error rate. More than 30% relative improvement was obtained for the envisaged tasks compared to MFCC parameterization.     

Nonorthogonal bases and phase decomposition: Properties and applications

In a previous paper [1] it was discussed the viability of functional analysis using as a basis a couple of generic functions, and hence vectorial decomposition. Here we complete the paradigm exploiting one of the analysis methodologies developed there, but applied to phase coordinates, so needing only one function as a basis. It will be shown that, thanks to the novel iterative analysis, any function satisfying a rather loose requisite is ontologically a basis. This in turn generalizes the polar version of the Fourier theorem to an ample class of nonorthogonal bases. The main advantage of this generalization is that it inherits some of the properties of the original Fourier theorem. As a result the new transform has a wide range of applications and some remarkable consequences. The new tool will be compared with wavelets and frames. Examples of analysis and reconstruction of functions using the developed algorithms and generic bases will be given. Some of the properties, and applications that can promptly benefit from the theory, will be discussed. The implementation of a matched filter for noise suppression will be used as an example of the potential of the theory.     

水电机组振动信号去噪的小波技术研究

概述了水电机组振动信号处理技术的现状,着重介绍小波技术中小波分析、小波包分析、第二代小波变换等特点及在水电机组振动信号去噪处理中的应用,并分析了水电机组振动信号去噪技术中的问题和前景。     

Global method for time–frequency analysis of harmonic distortion in power systems using the wavelet packet transform

The paper proposes a method based on the use of the wavelet packet transform for the time–frequency analysis of harmonic distortion in power systems. The magnitude of harmonic and interharmonic groups, as defined in Standard IEC 61000-4-7, the magnitude of the subharmonic group, defined as an extension of the standard method, and the time evolution of odd harmonics in voltage and current waveforms can be simultaneously computed using different levels of the same wavelet decomposition tree applied to the samples of the input signal. The paper shows the performance of the method proposed in different measurement conditions and the comparison of the results with those obtained applying the standard method.     

Harmonic wavelets based statistical linearization for response evolutionary power spectrum determination

A novel harmonic wavelets based statistical linearization approach is proposed for determining the evolutionary power spectrum (EPS) of the response of nonlinear oscillators subject to stochastic excitation. Specifically, first a mathematically rigorous wavelet-based representation of non-stationary stochastic processes is presented. Next, a representation of the process corresponding to a specific scale and translation level is derived. This procedure leads to an EPS estimation approach which is applicable for estimating not only separable but non-separable in time and frequency EPS as well. Several numerical results are presented in this context. Next, focusing on the case of the stochastic response of a linear system and relying on the orthogonality properties of the developed representation an excitation-response EPS relationship is derived. It is further shown that the excitation-response EPS relationship is valid even for linear time-variant (LTV) systems since the approach possesses inherently the element of time-dependence. Further, an extension via statistical linearization of the input-output EPS relationship for the case of a nonlinear system is developed. The approach involves the concept of assigning optimal and response dependent equivalent stiffness and damping elements corresponding to the specific frequency and time bands. This leads to an iterative determination of the EPS of the system response. Pertinent Monte Carlo simulations demonstrate the reliability and versatility of the approach.