http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Zhanqiang Xing,Jianfeng Qu,Yi Chai,Qiu Tang,Yuming Zhou 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2
The gear vibration signal is nonlinear and non-stationary, gear fault diagnosis under variable conditions has always been unsatisfactory. To solve this problem, an intelligent fault diagnosis method based on Intrinsic time-scale decomposition (ITD)-Singular value decomposition (SVD) and Support vector machine (SVM) is proposed in this paper. The ITD method is adopted to decompose the vibration signal of gearbox into several Proper rotation components (PRCs). Subsequently, the singular value decomposition is proposed to obtain the singular value vectors of the proper rotation components and improve the robustness of feature extraction under variable conditions. Finally, the Support vector machine is applied to classify the fault type of gear. According to the experimental results, the performance of ITD-SVD exceeds those of the time-frequency analysis methods with EMD and WPT combined with SVD for feature extraction, and the classifier of SVM outperforms those for K-nearest neighbors (K-NN) and Back propagation (BP). Moreover, the proposed approach can accurately diagnose and identify different fault types of gear under variable conditions.
Stability Analysis and Evaluation of ESR for Hysteresis Controlled Buck Converter
Jinlong WANG,Jinbin ZHAO,Jianfeng DAI,Keqing QU,Tiankai YE 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Buck converter using hysteresis controller has been widely used for power supply in industry applications owing to its instantaneous load transient. However the equivalent series resistance (ESR) of output capacitor has a significant effect for the stability performance. In this paper, the critical value of ESR is analyzed and calculated in the hysteresis controlled buck converter. Finally, simulation results indicate that the larger output capacitor ESR is necessary to make sure the converter operate normally, otherwise, the converter will operate abnormally.