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Improved CICA Algorithm Used for Single Channel Compound Fault Diagnosis of Rolling Bearings 被引量:13
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作者 CHEN Guohua QIE Longfei +1 位作者 ZHANG Aijun HAN Jin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第1期204-211,共8页
A Compound fault signal usually contains multiple characteristic signals and strong confusion noise, which makes it difficult to separate week fault signals from them through conventional ways, such as FFT-based envel... A Compound fault signal usually contains multiple characteristic signals and strong confusion noise, which makes it difficult to separate week fault signals from them through conventional ways, such as FFT-based envelope detection, wavelet transform or empirical mode decomposition individually. In order to realize single channel compound fault diagnosis of bearings and improve the diagnosis accuracy, an improved CICA algorithm named constrained independent component analysis based on the energy method (E-CICA) is proposed. With the approach, the single channel vibration signal is firstly decomposed into several wavelet coefficients by discrete wavelet transform(DWT) method for the purpose of obtaining multichannel signals. Then the envelope signals of the reconstructed wavelet coefficients are selected as the input of E-CICA algorithm, which fulfills the requirements that the number of sensors is greater than or equal to that of the source signals and makes it more suitable to be processed by CICA strategy. The frequency energy ratio(ER) of each wavelet reconstructed signal to the total energy of the given synchronous signal is calculated, and then the synchronous signal with maximum ER value is set as the reference signal accordingly. By this way, the reference signal contains a priori knowledge of fault source signal and the influence on fault signal extraction accuracy which is caused by the initial phase angle and the duty ratio of the reference signal in the traditional CICA algorithm is avoided. Experimental results show that E-CICA algorithm can effectively separate out the outer-race defect and the rollers defect from the single channel compound fault and fulfill the needs of compound fault diagnosis of rolling bearings, and the running time is 0.12% of that of the traditional CICA algorithm and the extraction accuracy is 1.4 times of that of CICA as well. The proposed research provides a new method to separate single channel compound fault signals. 展开更多
关键词 compound fault diagnosis energy method constrained independent component analysis(CICA) diserete wavelet transform(DWT)
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NUMERICAL PROCEDURE FOR 3D ELLIPTIC FLOW ON NONSTAGGERED GRIDS
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作者 张辉 陈善年 徐益谦 《Journal of Southeast University(English Edition)》 EI CAS 1995年第1期59-65,共7页
A finite difference numerical procedure and a sereralpurpose comput-er prosrani for 3D elliptic flow problems are developed, with the fictitious stag-gered-grids and the momentum interpolation technique on nonstaggere... A finite difference numerical procedure and a sereralpurpose comput-er prosrani for 3D elliptic flow problems are developed, with the fictitious stag-gered-grids and the momentum interpolation technique on nonstaggered grids.The algorithm and the computer 展开更多
关键词 FLUID dynamics FINITE DIFFERENCE method diseretization numericalsimulation
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Compressed Digital Video:Accelerating the Video Communications Revolution
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作者 Wen H. Chen (Compression Labs, Inc. 2860 Junction Ave SanJose ,CA 95134) 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 1994年第2期54-61,共8页
Video is used across a range of applicaticos,from low data-rate mdeo telephony to digitalbroadcast high deftnuzontelevision. Since all applications in thts range require that digually represent-ed sequece of images be... Video is used across a range of applicaticos,from low data-rate mdeo telephony to digitalbroadcast high deftnuzontelevision. Since all applications in thts range require that digually represent-ed sequece of images be reduced in let-rtue for efficient transmision or strage, all applications can uli-lize the same core compression technology. CLI has spent nearl two decades advancing the quality andapplication of digitof video technolegy and continues to rvaluaie meny video compression techniques in-cluding fractof coding, mavelets, subband coding, the discreie cisine transform (DCT), and vectorquantization. CLI currently has concluded that the discrete cosine transform (DCT) combined with mo-tion compensation provides the best pictrue quality for a wide range of video applicarions. In face, theDCT is the technology used by telecommunicationscomputer, and consumer video standards such as H.261 ,JPEG ,adn MPEG. This paper reviews these and other digital video compression iechnologies andthen discusses how CLI applies them to dtfferent video applications. Even within standardsbased mar-kets such as that for MPEG video ditribution syuerns, different products are differentiated easily bydifferences between their proprietary methods for preprocessing ,coding mode selection, postprocessing,etc. 展开更多
关键词 video compression technology diserete cosine trans form digital video processingmethod motion componsation
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Comparison of resonant current regulators for DFIG during grid voltage distortion 被引量:2
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作者 Yi-peng SONG Heng NIAN 《Journal of Zhejiang University-Science C(Computers and Electronics)》 SCIE EI 2013年第12期953-965,共13页
We investigate two different kinds of resonant current regulators for a doubly fed induction generator(DFIG) under distorted grid voltage conditions: proportional integral resonant(PIR) regulator with traditional reso... We investigate two different kinds of resonant current regulators for a doubly fed induction generator(DFIG) under distorted grid voltage conditions: proportional integral resonant(PIR) regulator with traditional resonant part and vector proportional integral(VPI) regulator with VPI resonant part. Based on the mathematical model of DFIG under distorted grid voltage, the transfer function and frequency response characteristics of the two current regulators are analyzed and compared. The superiority of the VPI current regulator over the PIR regulator is pointed out, and the influence of discretization methods on the performance of the resonant current regulator is studied. All the results are validated by MATLAB simulation and experiments. 展开更多
关键词 Doubly fed induction generator Harmonically distorted grid voltage Resonant current regulator Vector PI current regulator Diseretization method
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