共查询到19条相似文献,搜索用时 438 毫秒
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介绍了管道漏磁检测的原理,给出了管道检测装置框图。在小波变换Mallet快速算法的基础上,结合缺陷信号的特点,对实验室模拟状况下的采集信号进行了分析和处理,有效消除了信号噪声,提取了缺陷信号的特征值。 相似文献
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《组合机床与自动化加工技术》2021,(6)
在故障诊断过程中,为了更好地提取特征以及提高故障识别率,提出了一种基于离散小波变换和深度可分离神经网络算法以及SVM分类器的滚动轴承故障诊断方法。首先,模型利用离散小波变换对原始振动信号提取特征,形成多通道样本;然后对样本进行深度可分离卷积神经网络训练,最后在全连接层后接SVM分类器实现对故障信号的分类。实验所用数据来自CTU-2实验平台,故障标签共有10类。实验结果表明,相比较单一使用小波变换提取特征或者CNN卷积神经网络分类的方法,该模型的诊断效果更加优秀。 相似文献
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根据超声检测信号的瞬变特性,针对焊缝检测的缺陷分类问题,提出用判别追踪算法提取缺陷信号的局部时频判别特征,并结合概率神经网络实现了焊缝超声检测信号的缺陷分类.在提取时频判别特征时,提出考虑新选原子与已选原子的相关性的判别基提取方案,以降低特征之间的冗余,使提取出的特征能更有效地鉴别不同类别的缺陷.用该方法对一电子束焊缝试块中的缺陷进行了分类,结果表明,时频判别特征适合超声信号的缺陷分类,并能有效地抑制晶粒噪声的影响,考虑判别原子间相关性后可获得更高的分类正确率. 相似文献
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基于小波变换的混凝土超声探伤信号处理 总被引:4,自引:0,他引:4
将混凝土超声探伤信号的小波变换进行特征分析,提取了各级小波分解信号的谱特征,最后将这些特征输入模糊前向神经网络进行训练和分类,实验表明,这种方法具有良好的效果. 相似文献
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For quantitative flaw characterization in steam generator tubes, inversion of eddy current testing (ECT) signals in an automated fashion is strongly desired. In this paper, we report our effort to develop a systematic approach for flaw characterization in tubes by the novel combination of neural networks and finite element modeling.Specifically, the finite element model that can predict ECT signals from axisymmetric flaws in tubes was developed, and its accuracy was verified experimentally. Using this model, an abundant synthetic database with 400 ECT signals generated from 200 axisymmetric machined grooves in four types has been constructed with two test frequencies per flaw.For the automated inversion of ECT signals, a total of 22 features have been extracted from each flaw. Then, a set of 10 features has been selected for flaw classification, while the other set of 10 features for flaw sizing. For the determination of the flaw type and the flaw size parameters, we have proposed an intelligent flaw characterization system that adopts two different paradigms of neural networks: probabilistic neural networks for flaw classification and back propagation neural networks for flaw sizing.The performance of this system has been investigated using the synthetic ECT signals in the database. The excellent performance presented here, even though it has been obtained from synthetic flaws representing machined grooves in tubes, demonstrates the high potential of this system to serve as a robust tool for practical flaw characterization in tubes. 相似文献
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超声检测中,特定的缺陷回波信号一般都有一定的相关性,因而可利用自适应噪声抵消来增强缺陷回波信号。针对最小均方(LMS)算法自适应噪声抵消的缺点,提出了基于小波变换的自适应噪声抵消方法,通过Matlab软件将该算法应用于超声缺陷信号的仿真处理。结果表明,该算法大大提高了缺陷回波信号的信噪比,且具有较高的缺陷定位精度和纵向分辨率。 相似文献
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基于相关技术的超声检测信号处理 总被引:2,自引:0,他引:2
超声检测中,特定的缺陷回波与发射信号一般都具有一定相关性,因而可利用相关技术来增强缺陷回波信号。针对脉冲回波法的缺点,介绍了相关技术在超声检测中的应用原理,通过基于相关技术的超声缺陷信号处理的应用实例表明,在获得较好的运算经济性的情况下,能够把湮没在噪声中的信号提取出来,从而大大提高了缺陷信号的信噪比。 相似文献
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Time frequency and wavelet transform applied to selected problems in ultrasonics NDE 总被引:3,自引:0,他引:3
In this paper, we contribute by the development of some signal processing in order to enhance the sensibility of flaw detection, to measure thin materials thickness and to characterize defects in nature (planar or volumetric). Features for discrimination of detected echos are extracted in time domain, spectral domain and discrete wavelet representation. Compact feature vector obtained is then classified by different methods: K nearest neighbour algorithm, statistical Bayesian algorithm and artificial neural network. Mallat decomposition algorithm is also developed in order to enhance flaw detectability. Finally, time frequency algorithms based on STFT, Wigner–Ville, Gabor transform are developed and applied to thickness measurements of materials with small thickness. 相似文献
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On-line detection of the breakage of small diameter drills using current signature wavelet transform
This paper presents on-line tool breakage detection of small diameter drills by monitoring the AC servo motor current. The continuous wavelet transform was used to decompose the spindle AC servo motor current signal and the discrete wavelet transform was used to decompose the feed AC servo motor current signal in time–frequency domain. The tool breakage features were extracted from the decomposed signals. Experimental results show that the proposed monitoring system possessed an excellent on-line capability; in addition, it had a low sensitivity to change of the cutting conditions and high success rate for the detection of the breakage of small diameter drills. 相似文献