共查询到19条相似文献,搜索用时 140 毫秒
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为了实现刀具磨损状态监测的自动化与高精度,文章提出了一种基于希尔伯特-黄变换(hilbert-huang transform,HHT)和等距特征映射(isometric feature mapping,Isomap)的刀具磨损状态监测方法。首先采用经验模态分解算法对采集的信号进行降噪处理;然后对降噪后的信号进行Hilbert变换得到Hilbert时频谱,同时计算Hilbert边际谱及其统计特征量;最后利用Isomap算法进行特征融合及优化,将优化后特征向量送入支持向量机(support vector machine,SVM)中,并通过网格搜索法优化SVM的相关输入参数来建立最优分类模型。研究结果表明:Isomap算法具有较好的特征融合及降维效果,且Isomap-SVM分类模型对测试集的识别准确率为95%,文章所提方法可以有效地识别刀具磨损状态。 相似文献
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文章描述了基于振动信号的Morlet小波变换和HHT(Hilbert-Huang变换)齿轮故障信息提取方法,并分别用来对四类齿轮进行故障信息提取,得到各状态齿轮振动信号的Morlet小波谱和Hilbert谱。实验研究表明:Morlet小波变换和HHT都可用于齿轮故障信息提取,但Hilbert谱分析比Morlet小波谱分析在时间和频率域都有较高的分辨率,且HHT比Morlet小波变换有更高的计算效率,更适用于故障信号微弱、振动信号数据量大的齿轮故障信息提取。 相似文献
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研究用红外热成像法分析和评价焊缝材料内部缺陷的可能性。利用ANSYS Workbench建立金属焊缝气孔缺陷的红外热像检测瞬态热分析有限元模型,通过分别施加脉冲激励热载荷、不同频率的周期热载荷,模拟脉冲热成像和锁相热成像两种方法用的热源。针对焊缝缺陷深度评估精度,将脉冲热成像与锁相热成像两种方法进行对比研究。记录缺陷表面的温度场响应,并釆用傅立叶变换对仿真数据进行处理,求得不同深度缺陷的相位差,运用多项式拟合方法求得相位差与焊缝缺陷深度之间的定量关系。从结果总结出不同深度范围内焊缝缺陷检测的热源激励方式以及频率参数的选取,达到了较为满意的预测精度,为工程检测中焊缝缺陷热像检测的参数优化提供了参考,减少了参数重复设置而导致的时间浪费。 相似文献
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提出了一种基于复解析小波变换的相位诊断齿轮故障的方法。复解析小波变换将Hilbert变换与小波分析紧密结合在一起,具有自适应分析能力。利用复解析小波变换得到齿轮振动信号的相位,其功率谱图上可提取调制边频带结构来识别故障模式,试验结果表明这种方法可有效应用于齿轮局部故障诊断中。 相似文献
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针对风电机组齿轮箱运行工况复杂、背景噪声大,难以提取其故障特征信息的问题,提出一种基于变分模态分解(VMD)和分数阶希尔伯特变换(FHT)的风电机组齿轮箱故障特征提取方法。利用VMD分解风机齿轮箱各个故障信号,并且定义一种分解品质因数以选取VMD的最优分解层数K;对经最优化VMD分解后的各模态分量进行分数阶Hilbert变换,计算各模态分量的边际谱并进行线性叠加;提取该边际谱的频域特征作为齿轮箱故障信号的特征量。实验结果表明,采用该方法能够准确地提取出风机齿轮箱的故障特征,并获得更优的故障识别效果 相似文献
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Hilbert spectra, calculated with the Hilbert–Huang transform, are presented here as an analysis technique for the characterization of electrochemical noise data in corrosion studies. A highly detailed decomposition of the original current and potential data is provided in time and frequency simultaneously. Results on the decomposition of individual transients into their instantaneous frequencies at each moment in time are presented for five different corrosion processes: AISI304 in HCl solutions at different concentrations and AISI304 as well as mild steel in a 3 wt.% NaCl solution. The results demonstrate the potential of this technique to identify and distinguish different corrosion mechanisms. 相似文献
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为了应对空间碎片的威胁,研制了一种基于声发射技术的用于实时监测空间碎片撞击航天器的在轨感知系统。对平面声发射源精确定位技术提出了需求。声发射信号属于非平稳随机信号,传统的小波变换无法充分获得其中携带的信息。利用HHT技术分析声发射信号波形,改进了AO模态到达时刻的确定算法,提高了线定位精度。在此基础上,将平面定位问题转化为求取函数最小值的优化问题,并利用单纯形法进行求解。在铝合金板上对铅芯折断波源进行了定位试验,结果表明,相对于小波变换,HHT更适于分析声发射信号;改进后的线定位方法和双时标法可有效应用于各向同性板的定位问题。研究结果为空间碎片在轨感知系统的研制提供了参考。 相似文献
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A combined theoretical and experimental approach is reported using thermal-wave radar imaging (TRWI) for carbon fiber reinforced polymer (CFRP) with subsurface defects inspection. The multi-transform technique (Fourier transform, FT; Hilbert transform, HT; and cross-correlation, CC) is applied to extract the characteristics of thermal-wave signal. Experimental results indicate that the multi-transform technique of thermal-wave signal is available for detecting the subsurface defect. For the shallow defect (defect depth ≤1 mm), the delay time image of CC exhibits high contrast, and the phase image of FT has high SNR at the right frequency component. For the deep defect (defect depth 2.0 mm), the phase images of HT have both high contrast and large SNR value. 相似文献
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Chatter detection is an important task to improve productivity and part quality in the machining process. Since measured signals from sensors are usually contaminated by background noise and other disturbances, it is necessary to find efficient signal processing algorithms to identify the chatter as soon as possible. This paper presents an effective chatter identification method for the end milling process based on the study of two advanced signal processing techniques, i.e., wavelet package transform (WPT) and Hilbert–Huang transform (HHT). The WPT works as a preprocessor to denoise the measured signals and hence the performance of the HHT is enhanced. The proposed method consists of four steps. First, the measured signals are decomposed by the WPT, so that the chatter signals are allocated in a certain frequency band. Secondly, wavelet packets with rich chatter information are selected and are used to reconstruct new signals. Thirdly, the reconstructed signals are analyzed with HHT to obtain a Hilbert–Huang spectrum, which is a full time–frequency–energy distribution of the signals. Finally, the mean value and standard deviation of the Hilbert–Huang spectrum are calculated to detect the chatter and identify its levels as well. The proposed method is applied to the end milling process and the experimental results prove that the method can identify the chatter effectively. 相似文献
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针对磁控焊缝跟踪信号的非线性不平稳特点,提出了一种基于Hilbert-Huang变换和Cohen核的磁控电弧传感器焊缝跟踪系统的信号提取分析方法;运用经验模态分解,把周期激励下磁控跟踪信号分解成多个从高频到低频的本征模态函数分量,依据各分量的Hilbert边际谱,采用Cohen核分布的时频变换,能有效抑制交叉项,提取出磁控焊缝跟踪实时信号动态规律. 结果表明,利用此方法有助于更深入地揭示焊缝自动跟踪系统内各种干扰源的时频和频谱特征,为建立有激励源的焊接信号新的非线性模型提供了理论依据. 相似文献
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光干涉在光学元件面形测量中的应用 总被引:2,自引:0,他引:2
干涉计量技术由于能进行全场测量、非接触、精度和灵敏度高等特点在生产和研究中得到了广泛的应用。很多情况下,被测物理量和光学位相直接相关。本文从基本概念出发,介绍了光、光程、光程差和位相,对应用位相测量光学元件面形的原理做了详细的阐述,并简要列举了现在求取位相常用的方法:时间相移法、空间相移法、载波条纹的Fourier变换法和载波条纹的时域法。 相似文献