Ninghui Wang

Temperature Field Analysis and Process Control Strategies for MgO Single Crystal Production Using Adaptive Neuro-Fuzzy Inference System

To grow high-purity and large sizes MgO single crystals with twin-electrode DC submerged arc furnace requires that the temperature distribution be well understood and the processing temperature be precisely controlled. For the complexity of the production of MgO single crystals and the difficulty to measure the temperature inside the furnace, the temperature distribution was studied by using finite element method (FEM), and the temperature control was realized by the process control strategies with adaptive neuro-fuzzy inference system (ANFIS). Experiments were carried out to verify the effectiveness of the method. The result of experiments indicated that using the adaptive neuro-fuzzy control system can improve the quality and the quantity of the MgO single crystal production.

Temperature field analysis and adaptive neuro-fuzzy inference system for mgo single crystal production

The temperature field in MgO single crystal furnace is crucial to grow high-purity MgO single crystals with large sizes. In order to build proper temperature gradient, firstly finite element method (FEM) was used to study the temperature field distributions, and then a temperature controller with adaptive neurofuzzy inference system (ANFIS) was developed based on the result of FEM and practical experiences. When the temperature in MgO single crystal furnace was changed, the controller would regulate the positions of threephase electrodes and the voltage of the power simultaneously. The experimental results indicate that using the adaptive neuro-fuzzy control system can improve the quality and the quantity of the MgO single crystal production.

A Microcomputer-Based Predictive Digital Current Programmed Control System for Three- phase PWM Rectifier

The paper describes a microcomputer control system, which uses the floating-point digital signal processor TMS320LF2407 from Texas Instruments, for three-phase PWM rectifier. xa0It could effectively eliminate harmonic distortion of line currents and provides power factor correction. Moreover, it can be save electrical energy and reduction of production cost. In the control system, the predictive current control in two-dimensional (α-β) stationary frame, makes the input current following the phase voltage in phase to get unity power factor; and space vector pulse wide modulation (SVPWM) generates the modulation wave. Finally, the three-phase PWM rectifier using the proposed control system is designed in Simulink/Matlab and executed in laboratory prototype, and the results are provided to verify the proposed control system in the end of the paper.

Electric heating property from butyl rubber-loaded boron carbide composites

We researched the electric heating property from butyl rubber-loaded boron carbide composite. The effects of boron carbide content on bulk resistivity, voltage-current characteristic, thermal conductivity and thermal stability of boron carbide / butyl rubber (IIR) polymer composite were introduced. The analysis results indicated that the bulk resistivity decreased greatly with increasing boron carbide content, and when boron carbide content reached to 60%, the bulk resistivity achieved the minimum. Accordingly, electric heating behavior of the composite is strongly dependent on boron carbide content as well as applied voltage. The content of boron carbide was found to be effective in achieving high thermal conductivity in composite systems. The thermal conductivity of the composite material with added boron carbide was improved nearly 20 times than that of the pure IIR. The thermal stability test showed that, compared with pure IIR, the thermal stable time of composites was markedly extended, which indicated that the boron carbide can significantly improve the thermal stability of boron carbide / IIR composite.