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Study on Application of EMD and HOC in Fault Diagnosis for Rolling Bearings

YANG Wei-xin;JIANG Qin-yu;WANG Zhen;GUO Fang

2011, 31 (5): 142-145. DOI: 10.3969/j.issn.1006-1355-2011.05.033

Abstract （1693）

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Resonant demodulation is one of the most commonly used methods for rolling bearing fault diagnosis. However, this method is less effective sometimes since the early fault signal contains strong background noise. In this paper, a new denoising method based on empirical mode decomposition (EMD) and high-order cumulative quantities (HOC) is proposed. Fault signals are firstly decomposed into several intrinsic mode functions and then each function is analyzed and reconstructed using higher-order cumulative quantities. Finally, the fault characteristics of rolling bearing are extracted by using resonance demodulation. A practical example of fault diagnosis shows that this method has more preponderant than the traditional resonance demodulation method.

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Preliminary Study on “Noise Island” Topographic Distribution Method Applied in Urban Region Noise Monitoring Points Optimization

ZHAO Li-min;LI Ya-dan;;WANG Zheng;WANG Shuang-wei

2011, 31 (2): 142-146. DOI: 10.3969/j.issn.1006-1355-2011.02.034

Abstract （2271）

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Environmental noise pollution is influencing our daily life seriously. The regional noise pollution can be evaluated by using noise monitoring point optimization method. It has an important significance for planning and management of the environment. At present, there are some limitations for application of the environmental noise monitoring point optimization methods to urban regions in China. In this paper, the urban “Noise Island” concept is proposed. The environmental noise monitoring point optimization of an area in Changchun is carried out as an example applying the “Noise Island” topographic distribution method, with integrated neural network as the main technical means. The noise monitoring point is selected by using the “terrain” of the “Noise Island” for the first time. On this basis，the point selection and optimization rules of the best noise monitoring point distribution are found.

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Study on Natural Frequency Match in Mounting System Using Interval Response Method

BAO Jian;CHENG Ai-guo;HE Zhi-cheng;WANG Zhen

2011, 31 (2): 21-24. DOI: 10.3969/j.issn.1006-1355-2011.02.006

Abstract （2156）

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Uncertainty of stiffness of mounting system is a challengeable problem in manufacture of vehicles. In this paper, a simulation model of the mounting system based on the response surface method is built to solve the uncertainty conditions of the mounting system. Interval analysis method is adopted to transform the uncertainty model to a determinate model. And a quadratic programming optimization method is employed in the optimization of the non-probabilistic reliability model to obtain the reliable stiffness values. The results of a real industry problem demonstrate its practicability and reliability.

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《Time Series Distance Approach for RubImpact Fault Analysis of Rotor System Based on EMD-AR Method》

WANG Zhen;QI Gui-bing;JIANG Qin-yu;

2010, 30 (4): 72-75. DOI: 10.3969/j.issn.1006-1355.2010.04.020

Abstract （1761）

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In this paper, the nonlinear vibration signals of a rotor system with single point local rubimpact faults are decomposed into a number of intrinsic mode functions (IMF) with EMD method. The AR model for each IMF component is then established. Combining the Mahalanobis distance criterion function with KL information, an approach of time series distance analysis for the faults diagnoses is proposed. Experimental results show that this approach is good.

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《Approach Based on NonPrior Base Analysis for Improving Precision of Acoustic Holography Construction》

WANG Zheng-lun;ZHAO Xiao-dan

2009, 29 (5): 136-139.

Abstract （2288）

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Nearfield holography (NAH) measurement usually needs discrete Fourier transform (DFT) for spectrum analysis. When the signal is sampled in a nonsynchronous manner, the DFT spectrum analysis will yield leakage errors, which will reduce the reconstruction precision. A method based on nonprior base analysis is adopted. The base vectors are determined through searching the maximum peak value of the inner product. The covering effect of strong signals can be decreased, and the result is more accurate. This method is introduced to the NAH measurement to analyze the complex sound pressure on the holography surface. After that, the radiation sound field of point source is reconstructed. The result shows that the accuracy of sound field reconstruction is improved.

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