查询词典 wavelet

This paper combines with pipeline delivery of our countrys actual conditions and other methods of detection and location. To the leakage characteristic of the fault to the long-distance natural gas pipeline, a method is raised, which is on the basis of wavelet and negative-pressure-wave to detect the leakage and locate. Jobs in this paper are as follows:Multi-resolution decomposition and reconstruction of wavelet transform is utilized to filter the noises, which the leakage brings the noises of negative-pressure-wave. The research is worked in the wavelet and wavelet packet filter. The wavelet transform have a fast and accurate recognition capability to signal singularity. This paper chooses wavelet technology to catch the break point of pressure signal.

本文结合我国管道输送的实际情况和目前现有的各种泄漏检测与定位方法，针对天然气长输管线泄漏故障的特点，提出了基于小波分析和负压波相结合的方法检测泄漏并定位，其中主要进行了以下几个方面的工作：利用小波变换的多分辨率分解和重构技术，对采集到的管道发生泄漏时产生的负压波信号进行降噪处理，并对小波及小波包优化的降噪效果进行对比性研究；利用小波变换技术对信号奇异点的快速、准确的识别能力，捕捉负压波信号的突变点，从而判断是否有泄漏发生。

According to the feature of the SARS Chest Radiographic Images, the wavelet analysis method is put forward to dispose the SARS images and the wavelet coefficients are picked up. After the wavelet threshold noise reducing and the wavelet threshold enhancing disposure to the each of the wavelet coefficients, the clear images are reconstructed at last.

摘 要：通过对非典型肺炎的胸部 X 线图像的特征分析，提出采用小波分析方法，对图像做小波变换，提取各层小波分解系数，利用阈值法对各系数作去噪预处理，然后再利用阈值法对各系数做衰减或增强处理，最后重构出清晰图像。

This dissertation focuses on the spherical wavelet expansion of the earth gravity field and its application. Based on the concept of the integration approaches and radial basis functions the spherical wavelet is put forward, with that the earth gravity field is described in a new way, and some other researches are conducted, they are: spherical wavelet regularization, multiscale approximation of satellite gravity measurement, down continuation of airborne geavimetry data, the least squares properties of geopotential wavelet approximation, the spherical wavelet solution of two kinds of BVP and spherical selective multiscale reconstruction.

本文围绕地球重力场的球面小波展开及其应用进行研究，在积分逼近与径向基函数概念的基础上引入了球面小波，利用球面小波对重力场展开进行了重新表示，在此基础上进行了球面小波正则化、卫星重力多尺度逼近、航空重力数据向下延拓、重力场球面小波逼近的最小范数性质、两类边值问题的球面小波实用解、球面选择多尺度去噪方法等方面的研究。

In chapter 4, the Newlands harmonic wavelet is improved and a new type of wavelet with better time-frequency characteristic is constructed. Frequency band of signal can be divided arbitrary with the improved harmonic wavelet so that the phenomena of aliasing are reduced. Several typical fault signals in Electromechanical System are analyzed with it. In addition to the improved harmonic wavelet in chapter 4, a new half-complex wavelet is presented to improve the complex wavelet, which is given by Chaari.O. A unilateral recursive algorithm is derived to improve the real-time characteristic. A parameter n is imported to make the time-frequency and filtering characteristics of it better and its ability of extracting fault feature is enhanced.

第四章通过对Newland谐波小波的改进构造频域紧支撑、时域性能良好的新型小波函数，可实现信号频带的任意划分，从而减少频带混叠现象，采用改进的谐波小波对多种典型的机电系统故障信号进行了分析；以Chaari.O复小波为基础构造了一个半复小波，从提高复小波算法的实时性出发，推导了半复小波单向递推算法，通过给原小波设置可调参数的方法，实现了一种能满足小波基本条件的复值小波，可以通过参数的调整调节小波滤波器在Hilbert空间的时频特性和相应的滤波性能，以加强半复小波对故障特征的提取能力。

In this paper, we first discuss some basic theories about wavelet analysis, including some definitions about wavelet analysis, multi-resolution analysis, the decomposition and reconstruction algorithm of wavelet transform, orthonormal wavelet decomposition of the signal, and a few important properties of wavelet transform.

本论文中，我们首先讨论了小波分析的基本原理，包括了小波分析的基本概念，多分辨分析，小波变换的分解算法和重构算法，信号的正交小波分解，以及小波变换的几个相关的重要性质，这些都是我们进行研究和应用的基础。

First, the traffic flow time series chaotic feature is extracted by chaos theory. pretreatment for traffic flow time series, and the wavelet neural networks model was build by this. Second, the chaotic mechanism and the chaotic probability is described. Based on chaotic learning algorithm, and the wavelet neural networks fast learning algorithm of traffic flow time series is designed based on chaotic algorithm. Last, a single-step and multi-step prediction of traffic flow chaotic time series is researched by BP neural networks, wavelet neural networks and wavelet neural networks based on chaotic algorithm. The results showed that the wavelet neural networks predictive performance is better than the BP networks and the wavelet neural networks by the simulation results and root-mean-square value.

首先，通过混沌理论提取了交通流量时间序列的混沌特征，并在此基础上建立了小波神经网络交通流量时间序列模型；接着，阐述了混沌学习算法的混沌机理、混沌产生的概率，设计了基于混沌算法的小波神经网络交通流量混沌时间序列快速学习算法；最后利用交通流量混沌时间序列对BP网络、非混沌算法的小波神经网络以及基于混沌算法的小波神经网络进行了单步预测和多步预测，并对预测结果的仿真图和真实值与预测值的方均根进行了比较，结果表明基于混沌学习算法的小波神经网络的预测性能明显优于应用BP网络和非混沌算法的小波神经网络。

By using the Ricker wave- let and thin inter-beds model data,taking Morlet wavelet,MSW wavelet(A mother wavelet which can match seismic wavelet) and three parameters wavelet as mother wavelet respectively,the cal...

将该方法用于地下薄互层结构的地震响应分析，不仅可以刻画地层的整体变化特征，而且可以刻画薄互层内部结构。

Wavelet multi-resolution analysis is applied to decompose the signal into multiple-level and the wavelet coefficient modules of its high-frequency components are obtained. The wavelet coefficient modules of a broken signal can be extracted by software demising. The threshold of demising is decided by the difference between the wavelet coefficient modules of a broken signal and those of a noise. The wavelet coefficient modules of the broken signal were shown in different levels, then the faults can be detected and distinguished by the integrated features of the variant levels' wavelet coefficient modules.

利用小波多尺度分解技术，将信号进行多尺度的小波分解，得到不同尺度下的信号高频分量的小波系数模值，并根据奇变信号和噪声信号小波系数模值的差异，采用软阈值去噪法，对其高频分量小波系数进行去噪处理，获取不同尺度上突变信号的小波系数模值，实现对故障的检测，并可根据不同尺度上小波系数模值的对应关系，实现对多重并发故障的区分。

Daubechies'wavelet frame theorem is extended from one dimension to n dimensions. According to this framework, an example of n-dimensional radial wavelet is given. Differing from tensor product multidimensional wavelet, the radial wavelet is inseparable, locally supported and infinitely differentiable. The family, obtained by dilations and translations from this radial wavelet, constitutes a special type of radial wavelet frame in L〓.

Daubechies的框架定理推广到了n维情形，同时，也按照这一理论框架，给出了高维二进径向小波的具体例子，具有下列性质：ψ是无穷次连续可微的；ψ是局部支撑的，支集为‖x‖≤1；ψ含有分式因子，因此对&奇异点&更为敏感；ψ是不可分的，不同于张量积形式的高维小波；ψ是各向同性的。

Fifthly, the conception and the method of image compress is dissertated, also discusses the conception of wavelet transformation、continuous wavelet、discrete wavelet and multi-resolution analyses、Mallat algorithm, and do further research on the characteristic of wavelet images、the choice of wavelet bases and the continuation of image border, and based on this work, the way of freight train images compression combined with the wavelet and JPEG is put forward.

第五，论述了图象压缩的概念、方法，对小波变换的概念、连续小波、离散小波以及多分辨率分析、Mallat算法进行了讨论，并对小波图象的特点、小波基的选择以及图象边界的拓延进行了深入研究，在此基础上提出了小波和JPEG相结合的货车图象压缩方案。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。