共查询到20条相似文献,搜索用时 203 毫秒
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基于最优小波基的电机故障信号特征提取研究 总被引:2,自引:0,他引:2
小波变换去噪中最关键的问题是最优小波基的选取,使其能够将噪声从原始信号中分离出来。针对电机故障的特点,提出了一种基于信号的最优小波基选取方法。将信号小波变换的能量阈值曲线作为小波基函数的适用性评价指标。通过训练神经网络,选取适合该信号的最优小波基,最后采用平移不变量(TI)小波阈值法实现信号去噪。在此基础上对750W化纤电机进行了测试,实验结果表明,该方法能准确找出适合特定信号的最优小波基。训练后的神经网络可直接用于其它类型电机的信号去噪处理,具有实用价值。 相似文献
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小波变换在设备故障信号处理中得到广泛地应用,然而,小波变换只能消除白色噪声,对有色噪声不起作用.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,是信号的时间-频率-尺度变换,能根据信号的特点自适应生成新的时频窗口.它不仅具有小波变换良好的时频局部性特点,而且它的时频窗口比小波变换的时频窗口更加灵活.本文应用线调频小波变换对旋转机械故障信号进行消噪,效果明显. 相似文献
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分数阶小波包时频域的信号去噪新方法 总被引:2,自引:2,他引:0
为了提高信号去噪的效果,提出了一种基于分数阶小波包变换(FRWPT)的信号去噪新方法。该方法根据输出信号信噪比的大小,用迭代法寻找分数阶小波包变换的最优分数阶p值,通过分数阶小波包变换将带噪信号映射到最优分数阶小波包时频域内,对变换后的信号进行窄带通滤波,最后通过分数阶小波包逆变换对信号进行重构,实现分数阶小波包时频域内的信号去噪。以带噪Bumps信号和语音信号为例的去噪实验结果表明,采用该方法去噪后的信号信噪比明显提高,在抑制噪声的同时可以有效保持细节信息。 相似文献
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基于小波变换的车轮力传感器信号的去噪研究 总被引:1,自引:0,他引:1
在汽车道路试验中,通过多维车轮力传感器(WFT)可以测量每个轮所受的各维力和力矩。在测量过程中,信号会不可避免地受到各种噪声的干扰,而且,在将测量数据从车轮坐标系转换到车辆坐标系时,车轮转角的误差使测量结果产生了更严重的噪声。这些宽带随机噪声严重影响了车辆性能的分析。小波分析是一种信号的时间-尺度分析方法,特别适合于非平稳信号的分析,具有多分辨率分析特性,而且在时频两域都具有表征信号局部特征的能力。针对车轮力信号的特点,在MATLAB环境下编程进行车轮力信号小波变换去噪研究,试验结果表明,在选择了适当的小波基本函数和阈值的情况下,采用小波变换的闻值去噪方法对多维车轮力信号进行去噪处理,可以取得良好的效果。 相似文献
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超声回波信号反映了润滑油中磨粒的大量信息。为了提取淹没在强噪声环境下的超声回波信号,提出了一种基于双树复小波变换(DT-CWT)的油液磨粒超声散射回波信号去噪新方法。利用双树复小波变换具有近似平移不变性和有效去噪等优点,首先对超声散射回波信号进行双树复小波分解,然后对分解得到的高频系数进行阈值处理,最后进行双树复小波重构。结果表明:分解层数为6层时,去噪后信号的信噪比更高、均方误差更小、相似系数更大、幅值最大偏差更小。双树复小波变换硬阈值去噪效果比传统小波去噪效果明显好。 相似文献
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根据小波系数的相关分析理论,提出了基于双树复小波变换的小波相关滤波法。该方法根据相邻层小波系数的相关性,通过迭代过程自适应地进行滤波,能够在达到良好降噪效果的同时保留微弱故障特征信息。对降噪后的信号进行希尔伯特包络分析便可准确得到故障特征频率。试验信号分析与工程应用结果表明,该方法能够有效提取强背景噪声下的齿轮箱轴承早期故障特征信息。 相似文献
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Image processing is introduced to remove or reduce the noise and unwanted signal that deteriorate the quality of an image. Here, a single level two‐dimensional wavelet transform is applied to the image in order to obtain the wavelet transform sub‐band signal of an image. An estimation technique to predict the noise variance in an image is proposed, which is then fed into a Wiener filter to filter away the noise from the sub‐band of the image. The proposed filter is called adaptive tuning piecewise cubic Hermite interpolation with Wiener filter in the wavelet domain. The performance of this filter is compared with four existing filters: median filter, Gaussian smoothing filter, two level wavelet transform with Wiener filter and adaptive noise Wiener filter. Based on the results, the adaptive tuning piecewise cubic Hermite interpolation with Wiener filter in wavelet domain has better performance than the other four methods. 相似文献
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In the step processing a digitalized signal,noises are generated by internal or external causes of the system.In order to eliminate these noises,various methods are researched.Among these noise elimination methods,Fourier fast transform (FFT) and short-time Fourier transform (STFT) are widely used.Because they are expressed as a fixed time-frequency domain,they have the disadvantage that the time information about the signal is unknown.In order to overcome these limitations,by using the wavelet transform that provides a variety of time-frequency resolution,multi-resolution analysis can be analysed and a varying noise depending on the time characteristics can be removed more efficiently.Therefore,in this paper,a denoising method of underwater vehicle using discrete wavelet transform (DWT) is proposed. 相似文献
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虚拟仪器(VirtualInstrument,简称VI)是现代计算机软件技术、通信技术和测量技术相结合的产物。LabVIEW语言是美国NI公司推出的一款功能强大的虚拟仪器开发平台。小波变换的主要特点是通过变换能够充分突出某些方面的特征,它是研究信号时-频分析的重要方法。设计和实现了基于LabVIEW、利用小波变换的噪声测试系统;通过该测试系统可以对摩擦噪声进行测量和分析,有利于深入了解摩擦机理,改善摩擦条件,促进环保事业。 相似文献
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The continuous wavelet transform enables one to look at the evolution in the time scale joint representation plane. This advantage makes it very suitable for the detection of singularity generated by localized defects in the mechanical system. However, most of the applications of the continuous wavelet transform have widely focused on the use of Morlet wavelet transform. The complex Hermitian wavelet is constructed based on the first and the second derivatives of the Gaussian function to detect signal singularities. The Fourier spectrum of Hermitian wavelet is real; therefore, Hermitian wavelet does not affect the phase of a signal in the complex domain. This gives a desirable ability to extract the singularity characteristic of a signal precisely. In this study, Hermitian wavelet is used to diagnose the gear localized crack fault. The simulative and experimental results show that Hermitian wavelet can extract the transients from strong noise signals and can effectively diagnose the localized gear fault. 相似文献
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Kyung Joon Cha Kook-Hyun Yoo Chin Uk Lee Byeong Min Mun Suk Joo Bae 《Journal of Mechanical Science and Technology》2018,32(6):2453-2462
Harsh noises come from air-conditioning units are chronic complaining issues to their users. Individual perceptions of noise levels have been generally quantified by means of subjective evaluation such as a jury test. This article proposes a classification approach to acoustic noise signals using a wavelet spectrum analysis. We derive energy spectrums of noise signals using a discrete wavelet transform at pre-specified window length. The energy spectrums are a linear form and represented by a Hurst parameter as an informative summary of long-range dependent signal data. The Hurst parameter controls the self-similarity scaling as well as the degree of long-range dependence. We estimate the Hurst parameter through the least squares regression of sample energy against a resolution level in the wavelet spectral domain. In the context of multi-class classification problem, the classification of noise signals is performed by a nonlinear support vector machine (SVM) for parameter estimates of linear energy profiles containing the Hurst parameter. In an application example of air-conditioner noise signals, empirical results show that the proposed method offers the higher level of accuracy in acoustic noise sound classification. 相似文献