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Zhu D.-J.,Harbin Engineering University | Zhu D.-J.,Shanghai Aviation Electrical Corporation Ltd | Chu W.-H.,Shanghai Ocean University | Chu W.-H.,Collaborative Innovation Center for Distant Water Fisheries | And 3 more authors.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2015

A model for analyzing vehicle's pyroshock was established base on the SPH-FEM coupled method. With the SPH-FEM coupled method, SPH particles were used to discretize higher distortion regions for explosion bolts and finite elements were used to discretize a vehicle's separate structure.The characteristics of a vehicle's pyroshock were studied by changing explosion bolts initiation explosion sequence and initiation explosion interval. The numerical results agreed well with the experimental results, the validity and correctness of the model were verified. Study results showed that the best detonating sequence is to let the top and bottom bolts detonate firstly; explosion bolts detonate according to a certain order and time interval, this can effectively alleviate the explosion impact to the separate structure; the best initiation explosion time interval is 5.0e-5 s, and the bolts initiation explosion interval should not be more than 1.0e-4 s. ©, 2015, Chinese Vibration Engineering Society. All right reserved.

Fei S.-W.,Donghua University | Fei S.-W.,Shanghai JiaoTong University | He C.-X.,Shanghai JiaoTong University | He C.-X.,Shanghai Aviation Electrical Corporation Ltd
Recent Patents on Electrical and Electronic Engineering | Year: 2013

Fault diagnosis for motor bearing has a great economic and social significance, the patents on motor bearing fault detection and diagnosis method have been presented in the past years. However, there are some shortcomings including local extremum or over-fitting in the fault diagnosis method of these patents. Relevance vector machine (RVM), requires much fewer kernel functions compared with support vector machine (SVM), and provides the posterior distributions rather than just a point estimate. Thus, fault pattern recognition for motor bearing based on multi-layer RVM classifier was proposed in the paper, and two multi-class combination patterns of RVM classifiers including 'binary tree' and 'one-against-one' were used, among which 'binary tree' pattern is used to distinguish the fault state from the normal state, 'one-against-one' pattern was used to recognize the fault types. The fault pattern recognition results for motor bearing among RVM classifier, SVM classifier and RBF neural network (ANN) classifier were analyzed, and the experimental results indicate that RVM classifier has the better fault pattern recognition ability than SVM classifier or RBFNN classifier. © 2013 Bentham Science Publishers.

Zhao Y.,Shanghai University of Electric Power | Yuan Y.,Shanghai Aviation Electrical Corporation Ltd | Wei W.,Shanghai University of Electric Power
Journal of Computational Information Systems | Year: 2011

In this paper, a shape feature using Zernike moments for image hash is proposed. At first the image is pre-processed and the color space of processed image is transformed from RGB to YCbCr. Then these three components are mapped to a unit circle. Zernike moments of three image components are calculated and the amplitudes and phases of modified Zernike moments are connected to form the intermediate hash. At last, the final hash sequence is obtained by pseudo-randomly permuting the intermediate hash sequence. Similarity between hashes is measured by a new distance defined in this paper. Experimental results show that this method is robust against most content-preserving attacks. The threshold used in image authentication can be got by robustness and uniqueness tests. And this method can be used to detect image forgery involving structural and color modifications. © 2011 by Binary Information Press.

Zhang X.,University of Shanghai for Science and Technology | Chang M.,University of Shanghai for Science and Technology | Hou Y.,University of Shanghai for Science and Technology | Hou Y.,Shanghai Aviation Electrical Corporation Ltd
Optics Communications | Year: 2015

Moiré fringe technology has been widely used in the fields of measurements due to the good amplification characteristics and imaging characteristics. For the more generic case where the two crossed-gratings have different line spacing and the angle between the gratings is non-zero, the calculation for the Moiré fringe pattern tends to be rather complex. In this paper, a quantitative model of Moiré fringe patterns based on two crossed Ronchi-gratings is deduced. This is further propelled by the fact that the characteristics of Moiré fringe patterns tend to be simplified provided the pitch widths of two crossed-gratings are integral multiples. Numerical simulations and experimental setup have been carried out to ascertain the effectiveness and relevance of the proposed quantitative model. Results indicate that this model is satisfactorily justifiable and can be effectively applied especially when two gratings are integral multiples of each other. ©2015 Elsevier B.V. All rights reserved.

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