基于新型SVPWM调制策略的开绕组同步磁阻电机控制系统研究

本文介绍开绕组同步磁阻电机矢量控制系统,并详细介绍一种新型双逆变器SVPWM调制策略,使得双逆变器两象限交替低频工作,逆变器开关器件的损耗均分。在Matlab/Simulink平台构建了开绕组同步磁阻电机矢量控制系统仿真模型,以F2812DSP为控制核心搭建实验平台,实验与仿真结果验证了该方案可行。     

卫生部主抓四大工作强调食品安全五个重点

不久前，中国食品工业协会、国家发展改革委经济运行局、国家统计局工交司，联合在京召开2004年至今年第一季度全国食品工业经济运行情况发布会。会上，卫生部监督局苏志副司长就食品安全的种种问题、卫生部主抓的四项工作和“食品安全行动计划”强调的五个重点等内容，发表了精彩的讲话。     

食品添加剂监督管理

本刊在上期刊登了原卫生部卫生监督局局长、现任食品安全国家标准审评委员会食品添加剂分委员会主任委员、中国卫生监督协会常务副会长兼秘书长、中国卫生法学会副会长赵同刚先生题为"食品添加剂的作用与安全性控制"的演讲内容。本期将继续刊登在"食品添加剂安全性管理高层论坛"上权威专家的精彩发言,内容包括卫生部食品安全综合协调与卫生监督局苏志局长的"食品添加剂监督管理"、中国疾病预防控制中心营养与食品安全所、食品安全国家标准审评委员会秘书处张俭波的"我国食品添加剂标准化概况"和中国食品添加剂和配料协会薛毅秘书长的"加强行业自律和企业诚信,保障食品添加剂的安全生产与使用"。     

一类非线性发展方程的AGE方法与并行计算

为研究二维非线性发展方程适合于并行机上运行的高效率计算方法,给出了求解一类非线性发展方程的交替分组显示AGE方法,并得到了方法的无条件稳定性以及具有并行性兼顾的结果．数值结果说明．本方法具有良好的有效性、使用性．     

Control of flow separation over a wing model with plasma synthetic jets

An array of 30 plasma synthetic jet actuators (PSJAs) is deployed using a modified multichannel discharge circuit to suppress the flow separation over a straight-wing model. The lift and drag of the wing model are measured by a force balance, and the velocity fields over the suction surface are captured by a particle imaging velocimetry system. Results show that the flow separation of the straight wing originates from the middle of the model and expands towards the wingtips as the angle of attack increases. The flow separation can be suppressed effectively by the PSJAs array. The best flow control effect is achieved at a dimensionless discharge frequency of F⁺ = 1, with the peak lift coefficient increased by 10.5% and the stall angle postponed by 2°. To further optimize the power consumption of the PSJAs, the influence of the density of PSJAs on the flow control effect is investigated. A threshold of the density exits (with the spanwise spacing of PSJAs being 0.2 times of the chord length in the current research), below which the flow control effect starts to deteriorate remarkably. In addition, for comparison purposes, a dielectric barrier discharge (DBD) plasma actuator is installed at the same location of the PSJAs. At the same power consumption, 4.9% increase of the peak lift coefficient is achieved by DBD, while that achieved by PSJAs reaches 5.6%.