不同控制策略下并联混合型滤波器对系统谐振抑制特性的研究

并联混合型滤波器作为一种谐波抑制和无功补偿装置，结合了无源滤波器成本低、结构简单和有源滤波器控制灵活、可动态补偿等优点，成为近年来研究与应用的热点。并联混合型滤波器中，根据有源滤波器电流检测点的不同，其控制方法也不尽相同。本文分析了有源滤波器在不同电流检测点情况下系统的电路模型，在此基础上分析了不同控制方法下，有源滤波器对抑制电网和无源滤波器之间谐振的作用，并通过仿真进行了验证。     

与源电力滤波器设哥

以三相系统中的电网电流为研究对象,介绍了有源电力滤波器的系统结构和工作原理,讨论了主要元件参数的设计和计算。     

基于多电平变流器的有源电力滤波器研究

提出了一种基于多电平变流器的并联APF系统的电路拓扑结构,并在交直流控制策略和系统参数设计方面进行了系统的分析。仿真和实验结果表明基于CPS-SPWM技术级联H桥型多电平变流器的SAPF系统能够在较低的器件开关频率下实现较好补偿效果,具有良好的工业应用前景。     

主动磁悬浮轴承的工作原理及发展趋势

磁悬浮轴承是利用磁场力将转轴悬浮在磁场中，使转轴在空间无机械接触、无磨损地旋转的一种新型高性能轴承。与传统轴承相比，具有许多优点。介绍了主动磁悬浮轴承的结构和工作原理，提出了磁悬浮轴承的现存问题。     

XML和Java在工作流过程模型设计中的应用

工作流建模是工作流管理系统的基础和关键，而不同建模方法最终输出的过程模型描述是否标准化直接影响到工作流产品的互操作.在分析XML和Java技术特点的基础上，提出一种以XML中间文本为基础，结合XML和Java进行过程模型描述的方法，其中涉及过程模型中关键元素的XML?DTD描述、Java XML的数据绑定方法以及过程定义的存储.目的是使得跨平台应用得以按标准XML接口进行数据交换，进而较好地解决了上述问题.     

谐波检测方法的DSP实现方案

针对在有源滤波器设计过程中谐波电流的获取有很高的实时性要求，采用数字方法代替传统算法，来实现谐波电流的快速计算．数字方法实现谐波电流不但可以提高系统的实时性而且易于实现．文中在给出了基于DSP的软硬件的实现方案后，还通过仿真验证了其有效性和可行性．     

基于时／空滤波噪声抑制算法和活动轮廓模型的血管内超声图像边缘提取

为解决血管内超声（IVUS）图像中严重的血液斑点噪声影响边缘提取方法的有效性问题，采用一种时／空滤波方法对IYUS图像进行降噪预处理，基于活动轮廓模型（Snake模型）和IVUS图像的边缘对比度特征量，利用Hopfield神经网络并结合模拟退火算法自动提取IVUS图像的冠脉血管壁内、外膜边缘．实验结果表明，该方法对序列IVUS图像处理有较好的可重复性和鲁棒性．     

Characterization of plastic flow in two Zr-based bulk metallic glasses

1 Introduction Bulk metallic glasses (BMGs) have attracted a great attention due to their excellent properties, such as high strength, good wear resistance, excellent elasticity and easily forming in viscous state. However, structural applications are currently limited by the lack of macroscopic plasticity at room temperature, characterized by strain-softening which results in the formation of intense localized shear bands. Fracture typically occurs after very small plastic strain in compress…     

Phase transition in the Zr60Al15Ni25 bulk metallic glass subjected to rolling at room temperature

The microstructure evolution of the Zr₆₀Al₁₅Ni₂₅ metallic glass during rolling at room temperature is investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and high-resolution transmission electron microscopy (HREM). The results show that the values of full width at half maximum (FWHM) of the XRD patterns and exothermic enthalpy ΔH of DSC plots do not monotonically change with the variation of deformation degrees ɛ. As ɛ is not large than 20%, the values of FWHM and ΔH are lower than that of the as-cast state. When ɛ reaches 30%, the values of FWHM and ΔH become larger than that of the as-cast state, while their values begin to decrease again as ɛ reaches about 85%. These results indicate that the reversible transitions between ordered and disordered atomic configurations occur during rolling, which is further verified by the HREM images. The reversible phase transition can be explained by the competition between the diffusion controlled reordering and shear-induced disordering during rolling.