Distributed Optical Fiber Sensor for Multi-point Temperature Measurement

The distributed optical fiber sensing technology is overviewed, which is based on Raman scattering light theory. Basic operation principle, structure, system characteristics and signal processing are discussed. This structure and method of the signal processing possess of certain spatial resolution, hence will ensure the practicability of system.     

Enhancement of islanding-detection of distributed generation systems via wavelet transform-based approaches

In this paper, a wavelet transform-based approach is proposed to detect the occurrence of islanding events in distributed generation systems. Thanks to time–frequency localization capabilities exhibited by wavelet transform, the approach embedded with this transform technique has grasped the appearance of the islanding event in a highly effective manner. Moreover, for those regions which are in need of a better visualization, the proposed approach would serve as an efficient aid such that the mains power disconnection can be better distinguished. To validate the feasibility of this approach, the method has been validated through several scenarios. Test results supported the effectiveness of the method for the application considered.     

光接入网中DWMT调制技术的研究

研究了光纤－电缆调制解调器接入技术的上行信道调制方式，分析了离散小波多音（DWMT）调制与其它调制方式相比所具有的特点和优势，提出了DWMT调制解调器的实现模型，设计了使用DWMT调制解调器的光纤－电缆调制解调器双向传输的系统方案；并对DWMT调制的系统特性进行了计算机仿真分析。仿真结果表明，DWMT调制是一项能有效实用于光纤－电缆调制解调器系统上行信道的技术。     

爆破条件对爆破震动信号分析中小波包时频特征的影响

非平稳信号的小波包分析是在小波变换基础上发展起来的 ,它对小波分析中没有细分的高频部分进一步分解 ,从而能够对信号局部信息进行更为精细的掌握。爆破条件是影响爆破震动时频特征分布的主要因素之一。本研究中 ,针对在不同段药量、不同微差间隔时间及近似相同的其它条件下产生的爆破震动信号 ,运用小波包分析方法对其进行了时频分析 ,主要探讨了段药量、段微差间隔时间对爆破震动时频分布的影响规律。段药量对爆破震动波形时频特征的影响主要体现在各层小波包主振频带内的细节信号峰值质点振速方面 ,各细节信号的峰值质点振速随段药量增加而增大 ,但主振频带分布保持基本的一致性 ,同一主振频带下小波包细节信号的阻尼比也趋于一致 ;段微差时间间隔对爆破震动时频特征的影响主要表现在 :延长各主振频带小波包细节信号的振动持时 ,不同微差单段波形的叠加增加了主振频带个数 (优势频率个数 )并使各频带内的优势频率值有微弱增大的趋势     

Hardware and software architecture for power quality analysis

This paper presents a novel concept for power quality hardware and software architecture. Software tools related to detection, classification and characterization of power quality events can be integrated into a Distribution Control Center in which the interconnection between different subsystems is being carried out through the Internet allowing flexibility to the system. This system is implemented using wavelet analysis applied in all proposed algorithms. Different power quality events are taken as examples to illustrate the capabilities of the proposed method. The obtained results reveal that the proposed architecture is feasible to be implemented as an integral part of a control center system.The proposed system has the property of fast and accurate detection and classification of any power quality disturbance event and introduces a new PQ index determination that allows characterizing any type of disturbance including the non-periodic signals.     

基于纠错编码和小波变换的数字图像水印算法

文章提出了一种基于小波变换和纠错编码的数字图像水印算法,该算法不需要利用原始图像。实验结果表明,该算法较好地保持了图像的质量,并大大提高了检测的可靠性,对常见的图像处理方法显示了较强的鲁棒性。     

基于小波的彩色序列图象压缩编码

此文提出了一种基于小波变换的运动估计算法，时间复杂度比常规算法降低了一个数量级，同时在估值精度上可与常规算法媲美。利用更佳频率分辨率小波分解处理运动补偿余量误差善了复现图象质量。实验结果表明，该算法在高压缩比情况下图象复现质量显著优于ＭＰＥＧ－２，具有广阔的应用前景。     

WAVELET ALGORITHM FOR INTEGRAL OPERATOR EQUATION AND ITS APPLICATIONS TO ELECTROMAGNETIC PROBLEMS

A brief summary of the basic theory of wavelet is proposed. The properties of wavelet function are discussed. The possible applications of wavelet to electromagnetics are given. Examples show that the wavelet method is feasible and effective for solving electromagnetic problems.     

四气门汽油机缸内气流运动LDA测量结果的小波分析方法

主要采用小波分析方法研究了四气门汽油机缸内空气运动的频率结构。在一台四气门汽油机上 ,使用激光多普勒测速仪 (L DA)在倒拖工况下测量了气缸内的滚流运动 ,使用了 MATL AB 5 .1数学工具包中的小波分析方法对试验结果进行数据处理 ,得到了时域和频域分解速度信息。从这些信息中可以清楚地看到滚流 (低频湍流 )在压缩末期破碎并形成高频湍流的现象     

新颖的基于小波变换的数字水印方案

随着计算机网络技术与多媒体技术的快速发展，数字产品的版权保护已经成为信息技术领域中最重要的问题之一，提出了一种新颖的基于离散小波变换的数字水印方案，该方案利用改进的Pacthwork算法，将水印嵌入到LL子带中，水印信号在解码过程中无需使用原始图像可快速地重嵌入，该算法利用BCH码来降低误码率，应用所提出的算法，把一个32个字符的水印嵌入到图像中，实现结果表明水印是不可察觉的，经过JPEG有损压缩，低通与中值滤波等图像处理操作后仍是鲁棒的。