Papers by Author: Zi Chen Chen

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Authors: X.Y. Gang, Zhe He Yao, Zi Chen Chen
Abstract: Horizontal vibration has critical influence upon elevators’ ride quality. Based on the wave theory of one-dimensional string vibration, a horizontal vibration wave model is built to simulate the dynamic performance of a high speed elevator system. Through coordinate transformation, Galerkin’s method is used to discretize the governing partial differential equations into a dumped-mass system, which can be solved effectively with classic methods. Numerical results show that the horizontal vibration behaviors are closely interconnected with the location, velocity and acceleration of elevator cab.
Authors: X.Y. Gang, Zhe He Yao, Zi Chen Chen
Authors: Wen Wang, X.X. Li, Zi Chen Chen
Abstract: A planar capacitive sensor (PCS) is proposed for X and Y directions measurement. One axial displacement can be measured without the coupling of another axial movement. Two groups electrodes with 90 degree out-of-phase, forming triangle sine and triangle cosine wave, can be applied for direction detection and interpolation, aiming at high resolution. Simulation results show that proposed PCS is available for planar measurement.
Authors: Xin Li, Zhe He Yao, Zi Chen Chen
Abstract: Chatter often occurs during precision hole boring, it results in low quality of finished surface and even damages the cutting tool. In order to identify chatter rapidly and gain the precious time for chatter suppression, a chatter monitoring system was established and an effective feature extraction method for boring chatter recognition was presented. According to the characteristic of chatter signal, empirical mode decomposition (EMD) was introduced into chatter feature extraction, and its basic theories were investigated. The vibration signal was decomposed by EMD, then the intrinsic mode functions (IMF) was got. Finally, the feature of chatter symptom was extracted by analyzing the energy spectrum of each IMF. The results show that feature extracted from vibration of boring bar by EMD can indicate chatter outbreak symptom, and it can be used as feature vectors for rapidly recognizing chatter.
Authors: Hong Hua Zhou, Zhe He Yao, Zi Chen Chen
Abstract: Processing parameters of micro thixoforming, such as height-diameter ratio, die/punch temperature, billet temperature, and punch speed, have direct and complex impact on final quality of the workpiece, which is to be applied as the reaction plate of a microreactor for hydrogen production from methanol steam reforming. The micro/meso features of the workpiece, which is for catalyst loading, are micro-pin-fin arrays. Size of the surface area and uniformity of the pin-fins are quantified by average height (Ha) and relative standard deviation (RSD). An orthogonal experiment design is adopted to investigate the influence of the parameters on the semi-solid forming process. The results of the orthogonal experiment show that the optimum parameters are 150 °C for die/punch temperature, 576 °C for billet temperature, 0.14 for height-diameter ratio and 8.33 mm/s for punch speed. The experimental results validate that the optimized processing parameters can improve the quality of the reaction plate with micro-pin-fin arrays.
Authors: Fu Qiang He, Wen Wang, Zi Chen Chen
Abstract: The visual inspection system was developed for defects detection on leather surfaces, which is an important component of automatic CAD/CAM cutting systems. The main functions of the system are quality control and raw material cutting. An efficient algorithm, which combines multiresolution approach, energy and entropy matrices, is presented for detection of defects embedded in leather surface images. A wavelet band selection procedure was developed to automatically determine the number of resolution levels and decompose subimages for the best discrimination of defects and removals of repetitive texture patterns in the image. An adaptive binary thresholding is then used to separate the defective regions from the uniform gray-level background in the restored image. The proposed methodology is able to efficiently detect several types of defects that current approaches cannot detect, and is fast enough to be used for real-time leather inspection.
Authors: Chun Liang Zhang, Zhe He Yao, Zi Chen Chen
Authors: Chun Liang Zhang, Zhe He Yao, Zi Chen Chen
Authors: Jian Zhong Fu, Xiao Bing Mi, Yong He, Zi Chen Chen
Abstract: Theoretical analysis of the ionized fluid flowing through a cone-shaped nanopore is presented. The internal cross section of the cone-shaped channel is in the range from micro- to nanometer and gradual change from larger to smaller than the Debye length for the ions. The model is developed to predict the ionized fluid flow behaviors in cone-shaped micro/nanochannels. The velocity profiles of ion flow that occur in nanopores are obtained.
Authors: Zhe He Yao, Xin Li, Zi Chen Chen
Abstract: Self-chatter is a serious problem in cutting process. This paper aims to solve the problem by establishing time series model of vibration acceleration signal in cutting process based on Hidden Markov Model (HMM) technology and achieve the purpose of chatter recognition and prediction. Features which can indicate cutting state are extracted from the acceleration signal. HMM parameters are obtained by model training, and the reference models database is built. Then cutting state recognition is performed according to the feature matching level. Simulations and experiments are conducted, and the results show that the proposed method is feasible and it could get high recognition
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