Advanced Materials Research Vols. 383-390

Abstract: Passive power filter (PF) has problems that source impedance may strongly affect the filtering characteristics and cause system resonance in power system applications. Hybrid active power filter (HAPF) can improve the performance of passive filter and realize harmonics restraint and reactive power compensation in big power situation. In this paper, the principle of HAPF is analyzed, the model of HAPF is established, and the simulation results are discussed.

Abstract: This paper presents a local contrast enhancement method, which is able to improve the detection performance of edge-based human detection. First, a neighborhood dependent local contrast enhancement method is used to enhance the images contrast. Next, the cascade AdaBoost classifier is used to discriminate between human and non-human. Experimental results show that the performance of our method is about 5% better than that of the conventional method.

Abstract: In order to evaluate the harm and impact of power electronic devices on the grid and provide numerical basis for specific design of the corresponding compensated devices, the harmonics and reactive power of three-phase full-bridge controlled rectifier circuit with resistance-inductance load are studied in this paper. Firstly, the harmonics and power factor of the ac side current are analyzed theoretically; the harmonics contents and power factor are calculated. Secondly, the model of three-phase full-bridge controlled rectifier circuit is built in Matlab/Simulink, and the simulation analysis of the ac side power factor and harmonics is achieved, the simulated values are similar to the theoretical values. The results show that the complex calculations of harmonics and power factor can be completed simply and intuitively using simulation study, the simulation study is efficient and accurate.

Abstract: Ultrasonic attenuation coefficient of media phase is an important parameter in process tomography by amplitude method. At normal temperature (25°C), the experiment adopts continuous pulse string with the frequency of 0.5 MHz to measure ultrasonic attenuation coefficient of mud (average particle size about 300µm; water content 17%; mud-sand ratio 1:9). By the formula α= (1 / Z) 20lg (P0 / PZ), the attenuation coefficient of mud is calculated to be about 4.26×10-1dBcm – 1.

Abstract: This paper deals with trajectory tracking problem of a spherical mobile robot, BHQ-1. First, a desired velocity is obtained by proposing a PD controller based on the kinematics. Then a PD controller with an RBF (Radial Basis Function) neural network is proposed based on the desired velocity and the inexact dynamics. The weights of the RBF network are designed with an adaptive rule based on the tracking error, and hence the network can compensate the uncertainties of the dynamics more effectively. Stability is presented via Lyapunov Theory and simulation results are provided to illustrate the tracking performance.

Abstract: Based on the field equivalence principle and the potential function, the axial normalized pulsed power density of the microwave radiated from the circle aperture antenna was deduced. The power density in the Fresnel region was calculated for uniform aperture and tapered one. The relations between the aperture antenna’s maximum power and the parameters including pulse width, aperture radius and the center frequency were analyzed. The formula of the antenna’s maximum power limited by the air breakdown due to high power microwave is presented.

Abstract: Present a variety of advanced PID control algorithm in the use of induction heating power supply is increasingly broad, achieving good results in self-tuning of PID parameters. However, most of the output of PID control value is a single volume, such as DC power regulator for controlling the output voltage of rectifier or inverter power regulator for controlling the output frequency of inverter current. It has achieved a certain effect in the heat treatment process control, but did not take into account the actual efficiency of the power. The two adjustments will be combined in this article, using Smith prediction control algorithm and methods based on the Ziegler-Nichols PID tuning algorithm for time delay system. Both of the raising of induction power efficiency and lower system energy consumption has been achieved.

Abstract: This paper deals with on-line parameter identification of induction motors (IM) by means of least square techniques .Using stator voltages, stator currents and velocity as input-output data. For analytical identification by recursive least square (RLS) algorithms, filtering of experimental data is performed by means of anticausal filters. The simulation results show that error of the parameter estimation of the rotor resistance, self inductance of the rotor winding, as well as the stator leakage inductance are less than 5% .It demonstrate the practical use of the identification method.

Abstract: VAV air-conditioning system has the characters of nonlinear and non-stationary under the influence of many factors, so it is hard to tune the parameters of the fuzzy control system. According to the structure and operation principle of VAV air-conditioning system, the monitoring system has been developed. The conventional fuzzy control algorithm, temperature self-tuning parameters fuzzy control algorithm and variable universe adaptive fuzzy control algorithm were researched in the system. The relationship between the scale factors and several main performance indexes of the system's respond curve like overshoot, steady-state error and transient time has been analyzed. The experiments results indicate that the variable universe fuzzy control algorithm can improve the performance of the fuzzy controlle, the combination property index decreases over 17%. The algorithm is feasible to use it on line since it is simple and need few system resources.

Abstract: To assure the security and reliability of radio fuze, its performance must be test. A performance test system of radio fuze is developed, which is based on the theory of the pushing plate method according to the performance indexes written in the national military standard. The testing system which is composed of dipole antenna, frequency meter, multimeter and oscilloscope can test the main performance parameters of radio fuze. It is proved that the testing system can carry out the performance test of radio fuze steadily.