Analysis,simulation and verification of a bipolar current source power resonant inverter

A high‐frequency bipolar current source resonant inverter introduced in this paper has dramatic zero‐voltage‐switching (ZVS) characteristic. The analytic expressions of the resonant voltage and current are given. It indicates that the resonant waveform is composed of two parts, i.e. the oscillatory component and the stationary component. In special cases, the resonant waveform degenerates into the mono‐frequency component, as presents the graceful sinusoidal wave with very low total harmonic distortion (THD) value. Based on the closed‐form voltage and current, the component stresses on reactive elements are obtained. The impact of different component values and operating frequencies on ZVS feature is also discussed. It should be noted that the ZVS merit may be lost if the components are carelessly selected. The validity of the theoretical analysis has been proven with Pspice simulations and experimental results. Copyright © 2004 John Wiley Sons, Ltd.     

基于参考轨迹的自适应模糊Smith控制器

本文提出一种基于参考轨迹的自适应模糊Smith控制器,其模糊决策依据系统响应的参考轨迹,实现对Smith控制器参数的自整定.研究表明,该系统有较高的稳态精度和较强的鲁棒性.     

Bone Formation Process of β-TCP Ceramics with Tetracycline Tracing

To study the new bone formation in the bone defect area after implantation, the tetracycline tracing method was used. The results show that new bone formed in 1 month, and the formation rate of new bone was very high (8. 164 μm/day), considerably faster than that of control groups (3.219 μm/day). The new bone grew up quickly and β_TCP particles were surrounded by double fluorescence bands which became more obvious. The new bone formation rate was maximal at 2 months, and then gradually reduced. The rate was steady at 4 months, and then reduced to resembling as the normal physiologic metabolism of bone, which indicated the implanted materials were completely replaced by bone. Calcium phosphate materials had the ability of osteoconduction.     

运用ActionScript编程方法实现CAI课件页面动态处理

通过运用Flash MX内嵌的ActionScript语言开发多媒体课件的体会,介绍几种较具特色的ActionScript编程方法,实现CAI多媒体课件页面动态效果的设计处理方法.     

当代信息传播设计的趋势和走向

通过信息社会人类对信息感知的扩展性研究 ,从信息感知方式及思维形态的差异性来分析传统印刷文化与当代视屏文化的异同 ,以图形语言的变化来揭示当代视觉传播设计技术特征、视觉特征、多元化语言特征以及发展趋势     

燃料油硫含量分析准确度影响因素的探讨

研究了硫含量测定的影响因素，探讨了提高汽油中硫含量分析准确度的主要措施．试验结果表明：通过选取适宜的取样量，合适的灯芯疏密、粗细程度和灯芯位置高度及灯芯管内径，调节气流的大小，控制好火焰的形状和大小，可使燃料油中硫含量分析的准确度得到显著提高。     

Molecular dynamics studies of atomic-scale tribological characteristics for different sliding systems

A slider-slab sliding model for hard-to-soft and soft-to-soft sliding systems with abrasive and non-abrasive wear conditions is used to investigate atomic-scale friction. The molecular dynamics simulation uses the Morse potential to calculate interatomic forces between atoms. Separation distance between the slider and the slab is changed to simulate repulsive and attractive interactive force fields exerted on interface between two sliding components. Effects of the interaction potential parameters on the sliding friction are investigated. The relationship of frictional force, normal force and temperature rise of the slider and the slab during sliding are established. Comparison of the hard-to-soft and the soft-to-soft sliding system are carried out and shows different tribological phenomena.     

改进的最速下降法─最好点最速下降法

提出了用最速下降法解无约束多变量最优问题时，存在一些特殊点，本文称为最好点，这些最好点的负梯度方向总是直指目标函数的中心，即最优点．因此通过最好点一次迭代就能得到最优点．阐述了如何搜索得到最好的计算过程和计算程序．这个改进的最速下降法－最好点最速下降法既保持了最速下降法的优点，又消除了其锯齿现象，提高了计算速度．     

叶轮式分级机的环隙对分级性能的影响

有关环隙对叶轮式超细分级机性能的影响研究尚未有公开发表的资料,本文在这方面做了一些初步的实验研究。实验研究发现：环隙对分级性能的影响很大,把环隙作为调控参数很有前途。     

虚拟物流企业技术框架体系的构建

虚拟物流企业是现代物流发展的一个重要方向,是一种基于 Web 技术和信息交互的动态企业联盟,它的系统平台也不同于传统的物流企业。从虚拟物流企业的作业流程出发,构建了一个适合该类联盟企业的技术框架,并提出了系统中的信息管理方案。