Biblio

Optical time domain reflectometry (OTDR) plays an important role in optical fiber communications. To improve the performance of OTDR, we propose a method based on the Variational Mode Decomposition (VMD) and Hilbert transform (HT) for fiber events detection. Firstly, the variational mode decomposition is applied to decompose OTDR data into some intrinsic mode functions (imfs). To determine the decomposition mode number in VMD, an adaptive estimation method is introduced. Secondly, the Hilbert transform is utilized to obtain the instantaneous amplitude of the imf for events localization. Finally, the Dynamic Time Warping (DTW) is used for identifying the type of event. Experimental results show that the proposed method can locate events accurately. Compared with the Short-Time Fourier Transform (STFT) method, the VMD-HT method presents a higher accuracy in events localization, which indicates that the method is effective and applicable.

The reliability of mechanical equipment is very important for the security operation of large-scale equipment. This paper presents a rolling bearing fault diagnosis method based on Variational Mode Decomposition (VMD) and Convolutional Neural Network (CNN). This proposed method includes using VMD and CNN to extend multi-sensor data, extracting detailed features and achieve more robust sensor fusion. Representative features can be extracted automatically from the raw signals. The proposed method can extract features directly from data without prior knowledge. The effectiveness of this method is verified on Case Western Reserve University (CWRU) dataset. Compared with one sensor and traditional approaches using manual feature extraction, the results show the superior diagnosis performance of the proposed method. Because of the end-to-end feature learning ability, this method can be extended to other kinds of sensor mechanical fault diagnosis.