基于小波变换的TCSC输电线路保护新方法的研究

提出了基于B样条半正交小波的晶闸管控制的串联电容补偿(TCSC)输电线路保护新方法,该方法利用小波变换对TCSC输电线路两侧的电流信号进行分解,得到突变点的模极大值乘积符号,从而准确地区分内部故障和外部故障。利用实时数字仿真器(RTDS)对MOV正常工作及失效时的不同内外部故障类型进行了仿真。仿真结果表明,该方法简单可靠,且不受TCSC串补装置的影响。     

Detection of singularities in the pressure fluctuations of circulating fluidized beds based on wavelet modulus maximum method

Pressure fluctuations are often selected to analyze the dynamic changes in the gas-solid fluidized bed. In this study, the wavelet modulus maximum method is applied to analyze the pressure fluctuations in a circulating fluidized bed. Continuous wavelet transform is put on the pressure signals, then, maxima lines are extracted and the Lipschitz exponent, α, of every maximum line is calculated using the non-linear least-squares method. The mean of the negative α is adopted to describe the hydrodynamic characteristics in the circulating fluidized bed. The value of the mean of the negative α increases with the superficial gas velocity and turns stable when the flow regime is fast fluidization. This method has been tested effective under various operation conditions.     

一类新的知识型指纹图像非线性滤波方法

给出了基于小波变换的多尺度边缘表示方法及其对一般的图像信号表示的完备性和相应重建算法的稳定性,然后在小波变换的多尺度极大值表示方法的基础上,提出在尺度空间中基于多种知识的指纹图像非线性滤波方法.实验表明,这类滤波方法具有很强的自适应性,能取得令人满意的效果.     

基于Hermite插值的小波模极大值重构滤波的肌电信号消噪方法

为了消除混杂在肌电信号中的噪声,该文提出了基于Hermite插值的小波模极大值重构滤波的肌电信号消噪方法。该方法先对肌电信号进行小波分解;其次,根据小波系数的奇异性,利用信号与噪声模极大值在小波尺度上的不同变化特性,分离出信号与噪声;再次,用Hermite插值法重构小波系数;最后从重构的小波系数恢复成去噪后的信号。实验结果表明,Hermite插值的小波模极大值重构能有效地去除噪声,提高信噪比,且保留了肌电信号的细节信息,为肌电信号的特征提取和模式识别创造了良好的条件。     

A CHIM-based interactive Tchebycheff procedure for multiple objective decision making

This study presents a new solution procedure for multiple objective programming (MOP). It applies the concept of the normal boundary intersection (NBI) within the framework of the interactive weighted Tchebycheff procedure (IWTP). The proposed procedure is a collaborative approach to overcome the weak points inherent in both the NBI method and IWTP. In order to control the solution procedure of pinpointing a final solution properly, we parameterized the Pareto-frontier via a set of reference point vectors based on the convex hull of individual maxima (CHIM) instead of using the varying weights of each objective. Using well-distributed reference point vectors, we could identify well-distributed Pareto-optimal solutions, thereby eliminating the IWTP filtering stages and reducing the chance of missing the best compromise solution from the decision maker (DM)'s utility point of view. Moreover, by working with a sequence of progressively smaller subsets of reference point vectors, the DM can identify a final solution at earlier stages than with the IWTP.     

Exact and general FT1 penultimate distributions of extreme wind speeds drawn from tail-equivalent Weibull parents

We present a contribution to the current debate on methodologies for assessing extreme wind speeds. We review long-established extreme theory in the light of recent developments and show that it is unnecessary, indeed inappropriate, to resort to asymptotic models. We develop Cramér's method for the general penultimate distribution of extremes for the case of Weibull parents into a new model for extreme wind speeds that avoids the issues of asymptotic convergence and the associated errors. We demonstrate that the 30-year record of hourly mean wind speed at Boscombe Down, UK, has right-tail equivalence to the Weibull distribution and use this record to demonstrate the new model.     

小波变换 第3讲 二进小波变换及信号的奇异性检测

介绍了基于Ｂ样条的二进小波函数及二进小波变换的特性、算法,重点介绍了基于小波变换模极大值的信号奇异性检测理论,其要点是：信号可以通过其小波变换模极大值表示,也可通过其模极大值重构。因此,信号的表示变得异常简洁。由于二进小波变换具有平移不变性,从而在模式识别和信号的奇异性检测中获得广泛应用。     

基于子波变换极大值描述的图像压缩编码方法

本文给出了玫种有效的从图像子波变换模局部极大值点链接图像多尺度边缘曲线的跟踪算法。研究了基于基图像子波变换局部极大值描述的压缩编码方法。     

基于小波模极大值的湍动流态化流型转变特性研究

在提升管直径为0．06m,高度为5rn的冷态流化床试验装置上,使用基于信号奇异性检测的小波模极大值法,研究鼓泡流态化到湍动流态化的流型转变特性,获得相应的流型转变初始速度。使用压力波动平均振幅法和标准偏差法对压力波动信号进行分析,得到的转变初始速度相互之间的最大标准偏差为10．8％,说明这3种方法均能正确判断鼓泡流态化到湍动流态化的流型转变初始速度。与后两种方法相比,小波模极大值法有使用数据量少、分析速度快的优点。     

输电线路暂态电压行波的故障特征及其小波分析

分析了电压行波的基本故障特征 ,给出了电压行波故障特征的新的数学描述———小波表示。建立起了电压行波的故障特征和小波变换模极大值之间的联系 :通过有限个具有明确物理意义的小波变换模极大值 ,完整、清晰地刻划了暂态电压行波的故障特征。为构造性能优良、可靠的行波测距和行波保护奠定了重要的数学基础。