Advanced Materials Research Vols. 383-390

Abstract: Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) technology is a newly deve- loped power transmission technology. The basic principle and structure of multi-terminal VSC-HVDC is introduced and its steady-state mathematical model is set up. An improved power flow algorithm is deduced, which not only decouple the relationship between AC and DC systems’ variables in the strict mathematical form, but also can be integrated with the conventional power flow program and exhibit good accuracy and convergence characteristics compared to conventional technique. A numerical example of IEEE 14-bus test system with a 3-terminal VSC-HVDC network is given. The results show that the proposed steady-state model of multi-terminal VSC-HVDC and corresponding power flow algorithm are correct and effective.

Abstract: This paper establishes four kinds of Brushless Doubly-Fed Machine (BDFM) models with radial laminated magnetic-barrier rotor using ANSOFT finite element software, calculates the electromagnetic field of these four kinds of models, comparatively analyzes the magnetic field distribution, the torque capability, the end winding characteristics ,the rotor’s radial magnetic forces, the core losses and the motor operating performance of motor with different rotor structures, and thus provides theoretical guidance for optimization design of radial laminated magnetic-barrier rotor structure.

Abstract: Analysis on the characters of ground subsidence of Yangjiaping mining area, with same excavation depth and recovery coefficient, the numerical simulations to nonlinear large deformation using finite-difference method(FLAC) are achieved on the different strip extraction schemes that adopted different mining and reservation width. The result indicates that the subsidence values and horizontal deformation increases with the increasing of the strip extraction width on condition of the same recovery rate. Based on probability density function (PDF) method, the relationship of the coal pillar width, the mining width and ground deformation is acquired, which is some useful reference for using the strip extraction method to control the surface movement and deformation.

Abstract: The flow field distribution in burnt lime hydrator has been investigated by a software FLUENT, with k-ε turbulence model and MRF method. The simulation result shows that when four blades deflect 30°, the whole velocity gradient of flow reduces and the recirculation zones also diminish; when the rotational speed is 75r/min, the turbulence kinetic energy of stir zone between two axes becomes larger, which can raise stirring effect and reduce fugitive dust, so it is easy to achieve the purpose of improving the environment of work condition.

Abstract: Thermal stresses of grinding plays an important role on the fatigue and wear resistance of the component. A comprehensive analysis of thermal stress induced by surface grinding has been conducted with aid of the finite element method. To obtain a reliable figure of thermal stress induced by grinding, temperature-dependent properties of workpiece materials were taken into account. The developed finite element procedure has also been applied to calculate the surface and sub-surface thermal stress induced by moving source of triangular heat when convection and radiation is occurred over the whole work. Based on an analysis of the effects of wheel velocity on the thermal stress distributions in an elastic-plastic solid, some important conclusions were given.

Abstract: The discrete element code, EDEM, has been employed to simulate the axial mixing of size-binary particles in rotary kiln. Number of contacts has been introduced to track the progress of mixing and number of contacts between different particles has been took as mixing index between different particles to analyze the degree of mixing The results show that the larger velocity of particles in active layer is the main reason for the mixing; axial displacement of smaller particles is due to penetration of smaller particles through the intervals between larger particles.

Abstract: The increasing complexity of current SoC design brings a great challenge to SoC designer for fast SoC RTL integration and effective verification. In this paper, an automatic SoC integration methodology based on IP-XACT standard is proposed as a complete and effective solution for low-level RTL simulation, FPGA emulation and ASIC implementation. A bottom-up approach is adopted for design integration and verification from component level, to SoC core level, and then to final chip level. The three-core MPSoC case study not only gives the detailed usage and analysis on the proposed methodology, but also shows its efficiency to integrate a complex SoC design and its feasibility for correct SoC implementation.

Abstract: Starting with the Maxwell equations, this article introduces the heating power as intermediate variable to modeling of electromagnetic heating system, and gets a non-linear model. Concludes that the ralationship between the heat power and the input current is nonlinear, the temperature and the heating power is the first order linear relationship. The model has importance significances for improving the stability and accuracy of the electromanetic heating system .

Abstract: In this paper, we propose a piezoresistive accelerometer with the film- island structure, whose working range is up to 100,000g. Compared with the beam-island structure, the film-island structure has some advantages. With the film squeezed, the damping and the stiffness increase whereas the transverse sensitivity decreases. The fragmentation can be avoided in the overload situation. The damping characteristics, which are crucial for this accelerometer design, are theoretically analyzed in depth, and are verified by FEM simulation with ANSYS.

Abstract: This paper presents the algorithm of model predictive control (MPC) based on BP neural network to the burden system of the heating boiler. Because the burden system of the heating boiler is complex, the proposed approach uses steady, effective way to control the boiler. There is a closed-loop, repeating online optimization, model-based control algorithm which deals with the feedback information and the quantity of the fuel entering the boiler by the way of multi-step future predicting and compensating based on BP neural network. By simulation, it is demonstrated that the burden system of the heating boiler using MPC as control method is better in performance than the traditional PID. Besides, it is compliant to the model of the controlled object, especially to those which parameters of the model are variable.