基于线调频小波变换的电机故障信号谐波检测方法

线调频小波变换统一了短时Fourier变换和小波变换的时频分析，并能根据信号的特点自适应生成新的时频窗口。本文首次将线调频小波变换引进电力系统的突变信号处理中，分析了其消噪和滤除干扰的原理；构造了线调频小波变换的算法。该算法不仅能解决文[9]中提出的消噪和滤除干扰的问题，还能解决文[8，10]中提出关于滤除整数（偶数）次和分数次谐波，并通过对电力系统突变信号处理的实例说明该算法的突出优点。     

用小波变换测量功率因数

以功率因数为被控参数的SVC,需要测量功率因数。因而,本提出了用小波变换求功率因数的新方法,该方法对非正弦电压、电流信号进行正交小波分解,然后用分解系数求出电压、电流有效值和有功功率以及功率因数。中对该方法进行了仿真研究。     

基于小波变换的智能脱扣器改进算法研究

根据智能脱扣器的工作原理 ,针对常规傅立叶变换判断故障电流响应缓慢等问题 ,提出了利用小波变换和傅立叶变换的改进算法 ,将两种算法有机结合用小波算法找出故障信号中的突变点 ,再用傅立叶算法确定该突变点是否过阈值 ,得出真正的故障情况。这样充分发挥了小波算法检测突变信号的多尺度分析优点 ,保留了傅立叶算法的判据 ,避免了单独使用小波算法使可靠性降低的因素 ,为脱扣器准确动作提供了可靠保证     

论水利类高等职业技术教育的质量与可持续发展

教育质量是学校办学的关键 ,可持续发展战略呼唤新的、多元化的教育质量观 ;结合广东水利电力职业技术学院教育质量管理的实际情况 ,分析并提出了水利类高等职业技术院校教育质量可持续发展的现实对策及提升思路     

基于小波包分解的遥感图像压缩方法

基于小波包分解的遥感图像混合编码方法,首先将小波包分解后的低频和高频小波系数域值化为重要系数和非重要系数.低频重要系数采用无失真编码压缩.高频重要系数及其位置图,先用数学形态学方法进行聚类,再用标量量化和行程编码对重要系数和位置图分别编码.试验证明这种方法有效.     

结合Zernike矩的多尺度模板形状匹配

针对形状匹配中小波表达对起始点依赖的问题,提出一种结合Zernike矩的多尺度模板进行形状匹配的方法。该算法对输入图像进行预处理后提取目标轮廓,经过归一化处理得到目标形状的平移、尺度不变的链状表达,再通过小波变换进行多尺度分析;引入Zernike矩,利用Zernike矩的特性,实现小波表达的旋转不变性,解决了小波变换对起始点的依赖。匹配过程是以小波表达的各阶Zernike矩为特征向量,在由粗到精的尺度上进行的。实验结果表明,对于同一目标,原图像与旋转不同角度的图像的正确匹配率为91％。该算法适用于轮廓较明显的目标。     

基于小波的信号Lipschitz指数分析和应用

奇异信号往往带有一些重要信息,一般用Lipschitz指数来描述信号的奇异性。在Mallat等人的基础上讨论了奇异信号Lipschitz指数定义和相关理论基础,同时研究了小波变换与信号奇异性关系和Lipschitz指数的计算。利用信号和噪声奇异指数不同的特点应用于去噪声,文中提出了一种对噪声模极大值对应点周围的小波系数进行非线性压缩后重构信号新方法,仿真实验结果表明,这种方法有着较好的去噪效果。     

Dilation-run wavelet image coding

The run-length coding and the morphological representation are two classical schemes for wavelet image coding. The run-length coders have the advantage of simplicity by recording the lengths of zero-runs between significant wavelet coefficients but at the expense of yielding an inferior rate-distortion performance. The morphology-based coders, on the other hand, utilize the morphological dilation operation to delineate the clusters of significant coefficients for improving coding performance. In this paper, a novel dilation-run image coding algorithm is developed by taking the advantages of both schemes, in which the clustered significant coefficients are extracted by using the morphological dilation operation and the insignificant coefficients between the extracted clusters are coded by using the run-length coding method. The proposed dilation-run image coder is implemented in the framework of bitplane coding for producing embedded bitstreams. Compared with several state-of-the-art wavelet image coding methods, the proposed dilation-run image coding method achieves comparable rate-distortion coding performance, especially more attractive for fingerprint type of imageries.     

Cognitive Radio Dynamic Access Techniques

The ever growing demand for wireless services has placed enormous burden on valuable resources such as spectral bandwidth. This has resulted in a major rethinking in resource allocation policies culminating in an explosion of research activity in the field of Cognitive Radio (CR) towards optimum resource usage. In this tutorial paper the physical layer design and transmission techniques for CR in the context of efficient spectrum utilization are discussed. Spectrum sensing as the key element of CR awareness is described. Orthogonal frequency division multiplexing (OFDM) as a spectrally efficient modulation scheme is discussed and the rationale for its use in the CR system is explained. Spectrum pooling for efficient use of spectrum is studied and the role of adaptive OFDM techniques in this method is highlighted. Wavelet basis function as a replacement of Fourier transform in OFDM is evaluated. MIMO system as an added value to the CR performance is described. Adaptive Waveform and beamforming as alternative techniques in CR are reviewed.