共查询到19条相似文献,搜索用时 125 毫秒
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Fault Diagnosis of a Turbo—unit Based on Wavelet Packet Theory 总被引:3,自引:0,他引:3
In this paper we studied the fault feature of the generator set and the characteristics of wavelet packet theory for signal de-noising.The vibration signal of the generator set in different states is ana-lyzed by using the signal re-construction technique of the wavelet packet theory.The time domain method is given for the generator set fault diagnosis.The experiment results show that the wavelet packet theory can be used to directly identify the state of the generator set and provide a credible new idea for complex machinery fault diagnosis. 相似文献
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HU Zhi-wei TANG Yong LI Li-li 《国际设备工程与管理》2014,(2):122-128
Conclusion is that the soft threshold de-noising effect is better than hard threshold de-noising though the signal to noise ratio and Root Mean Square error. After analyzing, de-noising and reconstructing signal through wavelet packet from Matlab software, the average value of peak extracted from signal reconstruction is gotten to provide data for dynamic balance. Making use of the influence coefficient method to adjust drum of CTP dynamic balance, the program of Matlab is used to find phase position and weight of the mass block quickly, which can provide evidence for software for dynamic balance developed. 相似文献
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LIHong-kun MAXiao-fiang WANGZhen ZHUHong 《国际设备工程与管理》2003,8(4):233-238
The local wave method is a very good time-frequency method for nonstationary vibration signal analysis. But the interfering noise has a big influence on the accuracy of time-frequency analysis. The wavelet packet de-noising method can eliminate the interference of noise and improve the signal-noise-ratio. This paper uses the local wave method to decompose the de-noising signal and perform a time-frequency analysis. We can get better characteristics. Finally, an example of waveletpacket denoising and a local wave time-frequency spectrum application of diesel engine surface vibration signal is put forward. 相似文献
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CHEN Dan GAO Xiao-hong.School of Energy Power Engineering Wuhan University of Technology Wuhan P.R.China.School of Marine Engineering Jimei University Xiamen P.R.China 《国际设备工程与管理》2008,13(1):47-52
In the paper the aim and meaning of traffic microscopic simulation is discussed first, and then three sub-models of the system are established, e. i. the model for random generation of the vehicles, the model for car-following and lane change influenced by an adjacent vehicle, and the model for control and optimization of intersection with signal. Optimization of the traffic signal timing with a genetic algorithm and a microscopic simulation is carried out. It represents a novel approach to solving optimal signal timing. 相似文献
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ZHANG Xi ning WEN Guang rui LI Xin yi College of Mechanical Engineering Xi''''an Jiaotong University Xi''''an P.R.China Abstract: The feature of a periodic cyclic nonstationary signal for a cyclic working machine such as a diesel engine is studied in the aspect of working procedure force vibration. On the basis of the study a method of characteristic 《国际设备工程与管理》2003,8(1):35-40
The feature of a periodic cyclic-nonstationary signal for a cyclic working machine such as a diesel engine is studied in the aspect of working procedure,force and vibration.On the basis of the study,a method of characteristic abstraction and classification is put forward for periodic cyclic-non-stationary vibration signal.The proposed method is applied to experimental data of an ISUZU C240 diesel engine.Experiment results show the effectiveness of the proposed method in classification of engine faults. 相似文献
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Analysis of a Gyroscope's Rotor Nonlinear Supported Magnetic Field Based on the B-Spline Wavelet-FEM
LIU Jian-feng YUAN Gan-nan HUANG Xu YU Li 《国际设备工程与管理》2005,10(3):152-159
A supported framework of a gyroscope's rotor is designed and the B-Spline wavelet finite element model of nonlinear supported magnetic field is worked out. A new finite element space is studied in which the scaling function of the B-spline wavelet is considered as the shape function of a tetrahedton. The magnetic field is spited by an artificial absorbing body which used the condition of field radiating, so the solution is unique. The resolution is improved via the varying gradient of the B-spline function under the condition of unchanging gridding. So there are some advantages in dealing with the focus flux and a high varying gradient result from a nonlinear magnetic field. The result is more practical. Plots of flux and in the space is studied via simulating the supported system model. The results of the study are useful in the research of the supported magnetic system for the gyroscope rotor. 相似文献
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ZHAOHong XIAYong LIANGXiao-guo 《国际设备工程与管理》2003,8(3):154-162
There are few applications of image processing technology for diagnosing and state monitoring for internal combustion (IC) engines, which is discussed in detail in this paper. The time-frequetwy distribution images of cylinder head vibration signals are obtained by decomposing them with a wavelet packet algorithm. It is the first time that toe look at time-frequency distribution images from the point of images. Based on this, a new method for applying image processing technology for diagnosing and state monitoring for internal combustion engines is presented in this paper. A valve fault diagnosis model is set up by image matching, which is realized on a four-stroke, six-cylinder diesel engine. At the same time,some notes are presented in this paper. It has been proved that it is of no good effect to diagnose with histograms of time-frequency images generated by cylinder head vibration signals that have been processed with a wavelet packet algorithm. The reason is given in this paper. Comparisons of diagnosing effect are carried out between noise-added signals and original signals. It has little effect on diagnosing results after signals have been added with noise. The results show that this method has a clear physical meaning and is of good engineering practicability, feasibility, good precision and high speed. 相似文献
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LIXiang-jun WANGShu-zhen XUGuo-hua 《国际设备工程与管理》2004,9(2):91-96
The standard genetic algorithm has limitations of a low convergence rate and premature convergence in solving the job-shop scheduling problem. To overcome these limitations, this paper presents a new improved hybrid genetic algorithm on the basis of the idea of graft in botany. Through the introduction of a grafted population and crossover probability matrix, this algorithm accelerates the convergence rate greatly and also increases the ability to fight premature convergence. Finally, the approach is tested on a set of standard instances taken from the literature and compared with other approaches. The computation results validate the effectiveness of the proposed algorithm. 相似文献
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DUANChen-dong JIANGHong-kai HEZheng-jia 《国际设备工程与管理》2004,9(3):170-176
In order to make trend analysis and prediction to acquisition data in a mechanical equipment condition monitoring system, a new method of trend feature extraction and prediction of acquisition data is proposed which constructs an adaptive wavelet on the acquisition data by means of second generation wavelet transform (SGWT). Firstly, taking the vanishing moment number of the predictor as a constraint, the linear predictor and updater are designed according to the acquisition data by using symmetrical interpolating scheme. Then the trend of the data is obtained through doing SGWT decomposition, threshold processing and SGWT reconstruction. Secondly, under the constraint of the vanishing moment number of the predictor, another predictor based on the acquisition data is devised to predict the future trend of the data using a non-symmetrical interpolating scheme. A one-step prediction algorithm is presented to predict the future evolution trend with historical data. The proposed method obtained a desirable effect in peak-to-peak value trend analysis for a machine set in an oil refinery. 相似文献
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LIUQi-peng FENGQuan-ke XIONGWei 《国际设备工程与管理》2004,9(2):72-78
Fault diagnosis is confronted with two problems; how to “measure“ the growth of a fault and how to predict the remaining useful lifetime of such a failing component or machine. This paper attempts to solve these two problems by proposing a model of fault prognosis using wavelet basis neural network. Gaussian radial basis functions and Mexican hat wavelet frames are used as scaling functions and wavelets, respectively. The centers of the basis functions are calculated using a dyadic expansion scheme and a k-means clustering algorithm. 相似文献
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ABSTRACTTo improve the accuracy of the magnetic flux leakage (MFL) nondestructive testing in practical applications, it is very significant and key to deal with the detected MFL signals. As for the de-noising process of the MFL signals, a multilevel filtering approach based on wavelet de-noising combined with median filtering is proposed. By analyzing and comparing the de-noising properties of three wavelet families, i.e., Daubechies wavelet, Coiflets wavelet, and Symlets wavelet, two wavelet bases with the best de-noising performance are recognized and selected, namely sym6 and sym8 (the Symlets wavelet functions of order 6 and 8). Then, a new cascaded filter is constructed by combining sym6 and sym8 wavelets and cascading the median filtering method. An experimental platform is established to carry out the MFL testing, through the de-noising process for the measured MFL signals, and the results indicate that the proposed improved algorithm integrates with the merits of wavelet de-noising and median filtering. Compared with the traditional wavelet de-noising, the improved algorithm can not only improve the signal-to-noise ratio (SNR), but also reduce the de-noising error, resulting in enhancing signal quality to facilitate subsequent defect recognition. 相似文献
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小波阈值滤波是信号处理领域的重要方法,根据信号和白噪声在小波空间上传播的特性,提出了一种基于多假设检验确定小波滤波阈值的新算法。将小波阈值处理过程看作一个多重假设检验过程,FDR(False Discovery Rate)准则的step-up和step-down过程均能控制FDR在给定的显著性水平,综合这两个过程形成了FDR step-up-down过程并应用于确定小波滤波阈值。仿真实验表明,算法能够灵活调整显著性水平的大小来达到滤波后所希望的效果,以信噪比和均方误差作为衡量指标,本方法滤波效果与hearsure方法相当,优于BH FDR及sqtwolog方法。讨论了显著性水平的选取对滤波效果的影响,指出显著性水平的大小与信噪比的改善并非线性关系,提出了合理选取显著性水平的思路。 相似文献
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为了进一步降低桥梁健康监测采样信号的噪声水平,根据其信号特征,在传统EMD小波阈值降噪算法的基础上,提出一种改进的降噪算法,称为EMD小波相关降噪算法。该算法综合了EMD、小波变换和相关检测三种方法的优点,首先对各阶IMF小波降噪前后的分量分别进行整体和局部相关检测,并以前三阶整体相关系数的均值作为降噪阈值,最后进行局部相关阈值降噪,得到降噪后的信号。将该算法与EMD小波阈值降噪和小波默认阈值降噪算法进行数值仿真和有限元仿真试验对比,结果表明,提出的EMD小波相关降噪算法具有更好的降噪效果,能够用于桥梁健康监测采样信号降噪处理。 相似文献