ADAPTIVE MULTIRESOLUTION SPEECH ENHANCEMENT ALGORITHM BASED ON WAVELET TRANSFORM

In this paper, an adaptive multiresolution speech enhancement algorithm based on wavelet transform is put forward. It can make adaptive filtering to noise speech both at scales and among scales. So that the noise parts during the frequency intervals which decrease hearing quality mostly are reduced efficiently. Both the SNR and subject hearing quality of denoised speech are high and good.

Transient-Spatial Pattern Mining of Eddy Current Pulsed Thermography Using Wavelet Transform

Eddy current pulsed thermography（ECPT） is an emerging Non-destructive testing and evaluation（NDT E） technique, which uses hybrid eddy current and thermography NDT E techniques that enhances the detectability from their compensation. Currently, this technique is limited by the manual selection of proper contrast frames and the issue of improving the efficiency of defect detection of complex structure samples remains a challenge. In order to select a specific frame from transient thermal image sequences to maximize the contrast of thermal variation and defect pattern from complex structure samples, an energy driven approach to compute the coefficient energy of wavelet transform is proposed which has the potential of automatically selecting both optimal transient frame and spatial scale for defect detection using ECPT. According to analysis of the variation of different frequency component and the comparison study of the detection performance of different scale and wavelets, the frame at the end of heating phase is automatically selected as an optimal transient frame for defect detection. In addition, the detection capabilities of the complex structure samples can be enhanced through proper spatial scale and wavelet selection. The proposed method has successfully been applied to low speed impact damage detection of carbon fibre reinforced polymer（CFRP） composite as well as providing the guidance to improve the detectability of ECPT technique.

SUPPRESSING THE COHERENT SPECKLE OF SAR IMAGES WITH WAVELET ANALYSIS

This paper studies Synthetic Aperture Radar (SAR) images contaminated by the coherent speckle noise with the multiresolution analysis of wavelet transform. This study shows that the influences of the speckle on different frequency components of the SAR image are different, and that the SAR image and the speckle have different manners of singularity. So, this paper presents a denoising method of wavelet analysis to reduce the speckle. Some experiments approve that this method not only suppresses the speckle effectively, but also preserves as much target characteristics of the original image as possible. It shows that this denoising method of wavelet analysis offers a very attractive alternative to suppress the coherent speckle noise of the SAR image.

Application of multi-dimensional wavelet transform to fluid mechanics

This paper first reviews the application research works of wavelet transform on the fluid mechanics. Then the theories of continuous wavelet transform and multi-dimensional orthogonal(discrete) wavelet transform, including wavelet multiresolution analysis, are introduced. At last the applications of wavelet transform on 2 D and 3 D turbulent wakes and turbulent boundary layer flows are described based on the hot-wire, 2 D particle image velocimetry(PIV) and 3 D tomographic PIV.

MIXED SCHEME FOR IMAGE EDGE DETECTION BASED ON WAVELET TRANSFORM

A mixed scheme based on Wavelet Transformation (WT) is proposed for image edge detection. The scheme combines the wavelet transform and traditional Sobel and LoG (Laplacian of Gaussian) operator edge-detection algorithms. The precise theory analysis is given to show that the wavelet transformation has an advantage for signal processing. Simulation results show that the new scheme is better than only using the Sobel or LoG methods. Complexity analysis is also given and the conclusion is acceptable, therefore the proposed scheme is effective for edge detection.

Multiresolutional Maneuvering Target Tracking Fusion Algorithm Based on Singular Sensor and Multipale Models

Multiresolutional signal processing has been employed in image processing and computer vision to achieve improved performance that cannot be achieved using conventional signal processing techniques at only one resolution level [1,2,5,6] . In this paper,we have associated the thought of multiresolutional analysis with traditional Kalman filtering and proposed A new fusion algorithm based on singular Sensor and Multipale Models for maneuvering target tracking.

Wavelet-fractional Fourier transforms

This paper extends the definition of fractional Fourier transform （FRFT） proposed by Namias V by using other orthonormal bases for L^2（R） instead of Hermite-Gaussian functions. The new orthonormal basis is gained indirectly from multiresolution analysis and orthonormal wavelets. The so defined FRFT is called wavelets-fractional Fourier transform.

Oscillatory-Plus-Transient Signal Decomposition Using TQWT and MCA

This paper describes a method for decomposing a signal into the sum of an oscillatory component and a transient component. The process uses the tunable Q-factor wavelet transform (TQWT): The oscillatory component is modeled as a signal that can be sparsely denoted by high Q-factor TQWT;similarly, the transient component is modeled as a piecewise smooth signal that can be sparsely denoted using low Q-factor TQWT. Since the low and high Q-factor TQWT has low coherence, the morphological component analysis (MCA) can effectively decompose the signal into oscillatory and transient components. The corresponding optimization problem of MCA is resolved by the split augmented Lagrangian shrinkage algorithm (SALSA). The applications of the proposed method to speech, electroencephalo-graph (EEG), and electrocardiograph (ECG) signals are included.

BIVARIATE REAL-VALUED ORTHOGONAL PERIODIC WAVELETS

In this paper, we construct a kind of bivariate real-valued orthogonal periodic wavelets. The corre-sponding decomposition and reconstruction algorithms involve only 8 terms respectively which are very simple in practical computation. Moreover, the relation between periodic wavelets and Fourier series is also discussed.

Busbar Differential Relaying Method Based on Combined Amplitude and Phase Information of High Frequency Transient Currents

Busbar differential relaying method based on combined amplitude and phase information of high frequency transient currents is put forward in this paper for the speed and reliability problems of busbar protection based on fundamental frequency. Under the analysis of features of bus high frequency differential currents, complex wavelet analysis is used to extract the amplitude and phase features of 1/4 period high frequency differential currents, and amplitude and phase information are used to form the polar coordinates. Bus fault is identified intuitively and precisely according to polar locus differences. This polar coordinates represented busbar differential protection scheme based on high frequency transient signals can not only avoid TA saturation, realizing quick protection, lots of PSCAD/EMTDC simulations also show that this busbar differential protection scheme works well under different fault conditions.

NON-ORTHOGONAL P-WAVELET PACKETS ON THE HALF-LINE

In this paper, the notion of p-wavelet packets on the positive half-line P＋ is introduced. A new method for constructing non-orthogonal wavelet packets related to Walsh functions is developed by splitting the wavelet subspaces directly instead of using the lowpass and high-pass filters associated with the multiresolution analysis as used in the classical theory of wavelet packets. Further, the method overcomes the difficulty of constructing non-orthogonal wavelet packets of the dilation factor p 〉 2.

基于小波降噪和EMD-AR谱的地下电缆防破坏监测系统

电力电缆在当今社会发展和城市运作中扮演着非常重要的角色。随着人们用电量增加,电缆的铺设量也在同步增加。为防止电缆遭到破坏,对电缆管廊周围环境振动信号进行监测,及时发现潜在威胁,保障电缆正常工作,提出一种基于Matlab小波降噪算法和EMD-AR谱分析的地下电缆防破坏振动监测系统。该系统由太阳能供电模块、六轴陀螺仪姿态感应模块、振动传感器模块、物联网通信模块组成,主控芯片使用STM32F4单片机。采用小波阈值降噪算法去除复杂高频噪声,提高信号的可识别度,随后将去噪后信号进行经验模态分解(EMD),并对前6个固有模态函数(IMF)分量进行AR谱分析,最后将前6个IMF分量的AR谱累加得到信号的能量对比图。研究表明,该方法的应用准确分析出振动类型,能够给电缆管廊附近振动的监测分析提供更加简单便捷的方法,有效保护电缆的安全稳定运行。

基于小波分析的电流互感器局部暂态饱和识别方法

为精确捕捉电流互感器局部暂态饱和现象,保证电力系统的安全稳定运行,利用小波分析开展了电流互感器局部暂态饱和识别方法研究。首先,利用数据采集卡采集电流互感器二次侧电流信号,并对其进行去噪与放大预处理;其次,利用小波分析提取CT饱和状态特征,实现对饱和状态的准确表征。在此基础上,依据电流互感器饱和时的一些关键特性,设定局部暂态饱和状态阈值,与电流互感器运行特征进行比较,识别其是否进入局部暂态饱和状态。结果表明,应用该方法后,识别率均达到98%以上,显示出较高的灵敏度,能更准确地发现和识别出微弱的饱和迹象。

一种基于小波系数特征的遥感图像融合算法

多光谱图像和全色图像是目前卫星遥感领域最常见的传感器图像。为了更充分地发挥这两类遥感图像数据的价值,人们利用两类数据的互补性,将多传感器融合技术引进了遥感图像处理领域。在IHS彩色空间变换和小波多分辨率分析的基础上,利用图像高频小波系数的多个特征来定义特征量积,并利用特征量积作为依据提出了一种图像融合新算法。通过一组多光谱图像和全色图像数据进行融合仿真试验,并将该算法与IHS,HPF等算法和归一化矩算法作了比较。证明该方法能在保留多光谱图像光谱信息的基础上,有效地提高多光谱图像的空间分辨率。

基于小波分析的电力系统谐波分析

谐波对电力系统和用电设备产生了严重危害和影响。小波变换为电力系统谐波分析提供了有力的数学工具 ,利用基于多分辨分析的小波分析能将电压或电流等信号分解为基波信号和高次谐波信号。

基于小波分析的超高压输电线路无通信全线速动保护方案

提出了一种基于小波分析的输电线路无通信全线速动暂态保护的新方案。该方案利用小波变换构造两个不同中心频率的带通滤波器 ,提取故障生成的高频暂态信号。通过比较这两个频带内暂态信号的谱能量来实现区内外故障的准确识别。该方案无须通信通道 ,对故障类型、故障位置、过渡电阻及故障起始角不敏感 ,不受CT饱和、系统振荡、系统结构和运行方式的影响。ATP仿真初步证明了该方案的有效性。

基于小波多分辨率分析的电压暂降源定位研究

根据监测点的电压电流波形,基于小波多分辨率分析方法,分析暂降期间监测点三相瞬时功率信号,提取并计算低频段信号能量的变化,以其变化的正负极性判断暂降源相对于监测点的位置。线路故障、异步电动机启动、变压器投运是引起暂降的主要原因,用PSCAD建立了暂降仿真模型,对这三种类型暂降事件分别应用上述方法进行仿真验证,并对监测点受到干扰源影响的情况做了仿真。结果证明方法简洁可靠,可以用来进行暂降源定位的判断。

利用单端暂态量实现超高压输电线路全线速动保护新原理研究(一)——故障暂态过程分析及实现单端暂态量保护的可行性

在综述暂态量保护特别是反应单端暂态量的超高压输电线路全线速动保护的基础上 ,利用输电线路的波传导方程分析了故障暂态过程是由于故障点行波在输电线路上多次折、反射的叠加而形成。母线的杂散电容和阻波器等的存在 ,使得区内、外故障产生的暂态分量有差异 ,这种差异主要表现在暂态电压、电流波形的高频分量部分。利用DSP硬件手段和小波分析的数学工具 ,可以构成单端暂态量保护 ,实现全线速动。

现代行波故障测距系统的研制

介绍了一种采用现代行波故障测距技术的架空输电线路故障测距系统的构成、工作原理、功能配置及其在交直流输电系统中的应用实例。该系统由行波采集与处理系统、行波综合分析系统、远程维护系统以及公共电话网等 4部分构成 ,并且集成了 A,D,E等 3种现代行波故障测距原理以及多种暂态行波波形分析方法。该系统可以同时采集 8回线路的暂态电流 (来自常规电流互感器二次侧 )和暂态电压 (来自专门研制的行波耦合器 )信号。实际运行表明 ,该系统具有较高的准确性、可靠性、性能价格比以及较强的适应性和可维护性 ,其绝对测距误差可达 2 0 0

利用小波分析实现EHV输电线路单端量暂态保护的研究

介绍了连续小波变换定义、基于多分辨分析的Mallat快速小波分解算法。基于超高压 (EHV)输电线路故障暂态电流的特点和暂态保护的基本原理 ,充分利用小波分析的时频局部化特点 ,建立了基于小波分析的暂态保护启动判据和跳闸判据。借助EMTDC仿真分析软件 ,研究了一实际电网EHV输电线路故障电弧特点和在不同故障条件下保护判据的有效性。结果表明 ,基于小波分析的暂态保护方案是可行的。