Papers by Author: Su Xiang Qian

Abstract: Sound recognition based on neural network is a technique that can put a resolution to exceeding artificial identification. Three kinds of neural network recognition models, adopting MFCC and difference MFCC, are discussed. According to six kinds of typical gunshots we design a kind of sound recognition system based on BP neural network optimized by PSO that uses MFCC and difference MFCC as a characteristic quantity to recognize sound signal. In the experiment PSO is used to optimize the network’s initial weights and threshold value. The experiment’s results show that BP neural network optimized by PSO using both MFCC characteristic quantity and difference MFCC characteristic quantity have a relatively lower error and a relatively faster speed than other ways discussed in the article, and the designed system reaches the expected goal.

Abstract: Single-state grid-connected photovoltaic (PV) system has only one stage of power conversion and the control objectives needed to be considered simultaneously include synchronization with the utility voltage, harmonics reduction for grid-connected current and etc. Then the complexity of control strategy is increased. To deal with the characteristics, sliding mode controller is used to achieve the synchronization between grid-connected current and grid voltage and to control the waveform of grid-connected current, and the slide surface is designed based on PI method. Σ−Δ modulator is proposed to achieve the fixed switching frequency. Simulation results show that the system has good performance and the system is feasible.

Abstract: Power transformer is one of the most important electric equipments in power network, its running state has a direct effect on its safe operation of power network. Fault’s occurrence of power transformer probably result in vast hazards or accidents. According to statistics, its over-temperature operation of winding often result in different fault patterns, such as aging, breakdown and its burnt, etc, which has a large proportion in its accidents of power transformer. In this paper, based on the thermal analysis theory, a 3D thermal field model of transformer’s winding and core is respectively established in ANSYS software environment. And its 3D temperature field distribution of power transformer, including winding and core is simulated. Numerical simulated results provide a reliable and convenient reference for its thermal performance analysis of power transformer.is simulated. Numerical simulated results provide a reliable and convenient reference for its thermal performance analysis of power transformer.

Abstract: Its primary purpose of this study is to provide a comprehensive investigation on its dynamic performance of MR damper under high impact load. A test had been firstly done in order to identify its high shear viscosity of MR fluid. Then, its thermal performance of MR damper under high impact load is analyzed in order to aid its structure design of MR damper intended for weapon recoil mechanisms applications and improve its performance of elimination of heat. Further, Experimental analysis and performance evaluation of MR damper under impact load have been done by numerical simulation and hardware-in-the-loop simulation, including its acceleration response and pressure response of back cavity under different flow coefficient and the same inputting current, and its acceleration response and pressure response of back cavity under the same flow coefficient and different inputting current. Based on these simulation results, the shear-thinning phenomena and its dynamic response under saturated input current are analyzed and some useful conclusions are made. Finally, experimental results indicated that the developed MR damper under high impact load can achieve a good controllability for recoil applications.