A NEW METHOD FOR SOLVING MSDE BASED ON WAVELET NEURAL NETWORKS

In this paper, a new method to solve multiscale difference equation(MSDE) with the M-band wavelet neural networks is proposed. It is shown that the method has many advantages over the existing methods and enlarges the range of the solvable equations.     

基于小波变换的语音基频提取新算法

该文将小波变换应用于具有连续语音特征的三字词语音的基频提取,并针对实验中出现的问题对算法进行了改进,提出了一种新的基于小波变换的语音基频检测算法。该算法主要包括:离散小波变换计算、基于投票策略的基频点选择和基频起点确定、基频检查、异常点修正、头尾漏点处理以及基于投票策略的基频点精确定位。实验表明,该算法较好地克服了基于小波变换传统算法的不足,更适合于连续语音的基频提取,缺陷是需要较多的计算时间,不太适合于实时性要求较高的系统。     

小波阈值去噪的改进方法

利用小波方法去噪,是小波应用于工程实践一个重要的方面;本文指出了采用常见的阈值确定方法对含有较强高频分量的信号进行小波阈值去噪时,去噪效果与实时性存在着矛盾,不利于信号特征的提取。提出了一种新型的阈值确定方法,进一步提出了以小波去噪后特征频率分量的功率谱密度值的下降程度为依据的待定因子确定方法。以Mallat算法为例,对新型阈值确定方法进行了分析和比较,指出运用该方法进行小波去噪处理,增强了算法的实时性,同时信号拟关注的信息损失较小,去噪效果比较理想。交-交变频器输出电流的小波去噪实验结果表明,该方法行之有效。     

A new de-noising method based on 3-band wavelet and nonparametric adaptive estimation

Wavelet de-noising has been well known as an important method of signal de-noising. Recently,most of the research efforts about wavelet de-noising focus on how to select the threshold,where Donoho method is applied widely. Compared with traditional 2-band wavelet,3-band wavelet has advantages in many aspects. According to this theory,an adaptive signal de-noising method in 3-band wavelet domain based on nonparametric adaptive estimation is proposed. The experimental results show that in 3-band wavelet domain,the proposed method represents better characteristics than Donoho method in protecting detail and improving the signal-to-noise ratio of reconstruction signal.     

利用小波和分形理论进行水下回波的特征提取

该文首先分析了五类湖底回波的不同尺度下小波子空间的能量特征和分形维特征;然后将这些特征矢量作为分类的特征,并根据特征本身的离散程度对其进行加权;最后采用最小距离分类器对其进行分类,取得了 96.11％的分类正确率。     

A new fractal zerotree coding for wavelet image

Based on the mechanisms underlying the performance of fractal and Discrete Wavelet Transform(DWT), one method using fractal-based self-quantization coding way to code different subband coefficients of DWT is presented. Within this method finer coefficients are fractal encoded according to the successive coarser ones. Self-similarities inherent between parent and their children at the same spatial location of the adjacent scales of similar orientation are exploited to predict variation of information across wavelet scales. On the other hand, with respect to Human Visual System(HVS) model, we assign different error thresholds to different decomposition scales, and different shape of range blocks to different orientations of the same scale, by which the perceptually lossless high compression ratio can be achieved and the matching processing can be quickened dramatically.     

基于新阈值函数的小波阈值自适应去噪

针对传统小波阈值去噪算法中阈值估计和阈值函数选取的不足,提出一种高阶可导的阈值函数,并利用牛顿迭代法求得Sure无偏估计意义下的最佳阈值,从而实现阈值估计和阈值函数相关联的小波阈值自适应去噪.仿真实验表明,新算法可获得比传统阈值去噪算法更理想的去噪效果.     

基于小波变换的视觉信号特征提取方法

该文提出了一种用于视觉信号特征提取的新方法将CCD获取的图像投影后的信号波形进行小波变换。当小波的尺度选择恰当时,小波变换结果的零交叉点可用于确定图像的中心。实验结果表明,该方法相对于其他方法对随机误差的干扰具有更强的鲁棒性。     

一种改进的小波变换阈值去噪方法

Donoho等提出了一种基于小波变换的阈值去噪方法,这种方法在信号去噪及数据压缩等领域得到了广泛的应用。但是,Donoho设计的阈值处理方法对脉冲噪声的抑制效果不明显,因此在脉冲噪声存在的情况下,Donoho的阈值处理方法受到了限制。本文在Donoho方法基础上,设计了一种改进的阈值去噪方法,该方法对一大类的噪声信号有效,特别在保护信号边缘的同时去除脉冲噪声方面表现出了很好的特性。实验结果证实了该方法的有效性。     

A modified statistical approach for image fusion using wavelet transform

The fusion of images is an important technique within many disparate fields such as remote sensing, robotics and medical applications. For image fusion, selecting the required region from input images is a vital task. Recently, wavelet-based fusion techniques have been effectively used to integrate the perceptually important information generated by different imaging systems about the same scene. In this paper, a modified wavelet-based region level fusion algorithm for multi-spectral and multi-focus images is discussed. Here, the low frequency sub-bands are combined, not averaged, based on the edge information present in the high frequency sub-bands, so that the blur in fused image can be eliminated. The absolute mean and standard deviation of each image patch over 3 × 3 window in the high-frequency sub-bands are computed as activity measurement and are used to integrate the approximation band. The performance of the proposed algorithm is evaluated using the entropy, fusion symmetry and peak signal-to-noise ratio and is compared with recently published results. The experimental result proves that the proposed algorithm performs better in many applications.     

小波在多孤子相互作用数值研究中的应用

给出了研究多孤子在单模光纤中传播时相互作用的一种新的数值方法。它是基于导函数属于Ｈｉｌｌｂｅｒｔ 空间和Ｓｏｂｏｌｅｖ 空间中的基在Ｌ２ 范数意义下与Ｌ２（Ｉ） 空间的基的一致性,即在Ｓｏｂｏｌｅｖ 空间构造的小波基就是Ｌ２（Ｉ） 空间的小波基,从而可以导出用小波表示的导算子,并将它作用在非线性Ｓｃｈｒｏｄｉｎｇｅｒ 方程中的时间变量上, 得到一个新的迭代方程。用这种方法得到的结果与有关文献的一致,从而证明了其有效性     

一种基于小波变换的文字检测与提取方法

视频中包含的文字信息与视频的语义内容有很强的相关性,将视频中的文字信息提取出来进行分析处理可以有效地理解电视视频语义,从而实现对视频内容的安全监控。针对文字检测提出一种基于小波变换、角点特征图像和统计特征的有效方法,并运用基于彩色空间的文字提取方法获取二值图像,更有利于后面OCR的文字识别。     

一种新的SAR图像的相干斑滤波方法

该文分析了合成孔径雷达(SAR)图像中的相干斑(Speckle)的统计特性,基于小波变换(WT),提出了一种新的相干斑滤波方法,该方法将小波变换后的HH分量采用Lee滤波,对HG,GH和GG分量则利用恒虚警技术(CFAR),保留重要的目标和边缘,再将这四个分量进行重构。实验结果表明,该方法具有相当良好的相干斑抑制性能,等效视数得以大幅度提高,并且能很好地保持原图像的边沿特征,其性能明显优于通常采用的Lee算法。     

激光陀螺小波滤波方法研究

为了减小激光陀螺随机误差对激光捷联惯导系统对准、导航精度的影响,采用小波分析方法对其输出信号进行滤波处理.开发了评估软件,并对其在实际系统中滤波前后效果进行了深入研究.结果表明,评估软件准确可靠,小波分析方法简单实用,特别适合激光陀螺信号的处理,在很大程度上提高了系统对准、导航精度.     

A new hybrid wavelet-Kalman filter method for the estimation of dynamic system

A new hybrid wavelet-Kalman filter method for the estimation of dynamic system is developed, Using this method, the real-time multiscale estimation of the dynamic system is implemented, and the observation equation established is for the object signal itself rather than its wavelet decomposition. The simulation results show that this method can be used to estimate the object＇s state of the stacked system, which is the foundation of multiscale data fusion; besides the performance of the new algorithm developed in the letter is almost optimal.     

基于小波包分析的激光陀螺信号滤波方法

各种随机噪声是激光陀螺误差的主要来源。为了减少激光陀螺的随机误差,提高其测量精度,介绍了基于小波包分析的滤波方法,研究了小波包分析和滤波的原理、熵标准和阈值函数的选取,比较了选择不同熵标准、阈值函数对激光陀螺信号滤波的效果,并采用Allan方差法分析滤波效果。结果表明基于小波包分析的滤波方法能有效减小随机误差,提高激光陀螺的测量精度。     

一种基于小波包的语音信号特征提取方法研究

为了提高语音信号的识别率,提出了一种基于小波包的语音信号特征提取方法。该方法先对语音信号进行适当尺度的分解,求得各尺度的频谱,在此基础上得到各尺度信号能量,再通过DCT变换获得最后的特征参数。通过仿真实验,说明了新特征参数取得了较高的识别率。     

A study of wavelet entropy measure definition and its application for fault feature pick-up and classification

Shannon entropy in time domain is a measure of signal or system uncertainty.When based on spectrum entropy,Shannon entropy can be taken as a measure of signal or system complexity. Therefore,wavelet analysis based on wavelet entropy measure can signify the complexity of non-steady signal or system in both time and frequency domain.In this paper,in order to meet the requirements of post-analysis on abundant wavelet transform result data and the need of information mergence,the basic definition of wavelet entropy measure is proposed,corresponding algorithms of several wavelet entropies,such as wavelet average entropy,wavelet time-frequency entropy,wavelet distance entropy, etc.are put forward,and the physical meanings of these entropies are analyzed as well.The application principle of wavelet entropy measure in ElectroEncephaloGraphy (EEG) signal analysis,mechanical fault diagnosis,fault detection and classification in power system are analyzed.Finally,take the transmission line fault detection in power system for example,simulations in two different systems,a 10kV automatic blocking and continuous power transmission line and a 500kV Extra High Voltage (EHV) transmission line,are carried out,and the two methods,wavelet entropy and wavelet modulus maxima,are compared,the results show feasibility and application prospect of the six wavelet entro- pies.     

噪声背景下雷达低速小目标检测的一种新方法

该文在研究Duffing振子特性之后,基于Duffing振子与小波变换和神经网络相结合,提出了一种适用于低速小目标的Duffing振子雷达检测新方法。仿真实验表明,该检测方法能在低信噪比环境中,以低虚警率对低速目标进行有效检测。     

A new TDOA estimation method in Three-satellite interference localisation

Time difference of arrival (TDOA) parameter estimation is the key to Three-satellite interference localisation. Therefore, in order to improve the accuracy of Three-satellite interference location, we must estimate the TDOA parameter accurately and effectively. Based on the study of wavelet transform correlation TDOA estimation algorithm, combining with correlation and Hilbert subtraction method, we put forward a high precision TDOA estimation method for Three-satellite interference location. The proposed algorithm utilises the characteristics of the zero-crossing point of Hilbert transform method corresponding to the correlation peak point of correlation method, using correlation function of wavelet transform correlation method minus the absolute value of its Hilbert transform, to sharpen peak point and improve the TDOA estimation precision, so that the positioning is more accurate and effective.