Small signal modelling for the PWM series resonant converter

A discrete time domain modelling is presented for the pulse-width modulated series resonant converter (PWM-SRC) with a discontinuous current mode. This nonlinear system is linearized about its equilibrium state to obtain a linear discrete time model for the investigation of small signal performances such as the stability and transient response. The usefulness of this small signal model is verified by dynamic simulation.     

Microstructure of fast tool servo machining on copper alloy

The development of the fast tool servo (FTS) for precision machining was investigated.The micron machining performance of a piezoelectric-assisted FTS on copper alloy was evaluated.The results indicate that the quality of the microstructure depends mainly on two important factors:the cutting speed (or spindle speed) and the driving frequency of the FTS.The excessive driving frequency increases the formation of burrs.The effect of the clearance angle of the diamond tool on the microstructure machining precision was also investigated.     

DIRECT NUMERICAL SIMULATIONS OF THE DYNAMICS OF PARTICLES WITH ARBITRARY SHAPES IN SHEAR FLOWS

A fluid-structure interaction method based on the arbitrary Lagrangian-Eulerian method and a dynamic mesh method was developed to simulate the dynamics of a rigid particle in shear flows. In the method, the governing equations for the fluid flow and particle motion were sequentially solved in a two-way coupling fashion. The mesh system was deformed or re-meshed by the dynamic mesh method. The method was employed to simulate the dynamics of a single particle suspended in a flow channel and the dynamics of the particle were studied. The simulation results show that the angular velocity is not only a function of the inclination angle, is but also influenced by the aspect ratio yielding a hysteresis, while the angular velocity obtained from the Keller-Scalak model is a function only of the inclination angle and does not show a hysteresis. The present simulations clearly demonstrate that the Fluid-Structure Interaction (FSI) module is very stable, accurate and robust.     

Context-aware Workflow Model for Supporting Composite Workflows

-In recent years,several researchers have applied workflow technologies for service automation on ubiquitous computing environments.However,most context-aware oprkflows do not offer a method to compose several workflows in order to get more large-scale or complicated workflow.They only provide a simple workflow model,not a composite workflow model.In this paper,the autorhs propose a context-aware worrkflow model to support composite workflows by expanding the patterns of the existing context-aware workflows,which support the basic workflow patterns.The suggested worklow modei offers composite workflow patterns for a context-aware workflow,which consists of various flow patterns,such as simple,split,parallel flows,and subflow.With the suggested model,the model can easily reuse few of existing workflows to make a new workflow.As a result,it can save the development efforts and time of cantext-aware workflows and increase the workflow reusability.Therefore,the suggested model is expected to make it easy to develop applications related to context-aware workflow services on ubiquitous computing environments.     

High-intensity laser-driven particle and electromagnetic wave sources for science, industry, and medicine

We simultaneously observed both the fast proton generation and terahertz (THz) radiation in the laser pulse interaction with a thin-foil target.The maximum proton energy of ～2.3 MeV and an intense THz radiation were observed at the pulse duration of ～30fs.We also measured the proton beam and UV harmonics from a thin-foil target by changing the laser pulse duration.In the case of the ～500 fs, peaks of UV harmonics up to fourth order appeared.This unique combination of the multiple beams will provide useful applications such as pump-probe experiments.     

动态电压恢复器研究综述

动态电压恢复器（DVR）作为一种重要的用户电力装置，受到国内外研究者的广泛关注。首先介绍DVR的工作原理和基本结构，然后从拓扑结构、补偿策略以及控制方法几个方面对现有文献进行综述。最后对DVR的研究发展进行了探讨。