有源电力滤波器中空间矢量脉宽调制模块的仿真研究

介绍了空间矢量脉宽调制(SVPWM)的基本原理,提出了在Matlab/Simulink环境下用S函数实现空间矢量脉宽调制模块的方法,描述了仿真模型的设计过程和编程要点,并将其应用到有源电力滤波器的仿真系统中。给出了仿真结果,为基于SVPWM的有源电力滤波器的研究打下了基础。     

基于“活动记录”的面向对象软件开发实践

为了解决在面向对象软件开发中对象和关系数据之间的复杂映射问题,人们开创并积淀了很多方法,本文以活动记录(Active Record)这一新兴模式的实现为基础,探讨在解释性语言编程环境下面向对象的软件设计和开发实践过程。     

在主动信息服务中两种《EI》检索方案比较研究

文章介绍了两种用于主动信息服务业的论文收录的检索方案.利用刊物形式的以手工检索为基础,借助<中国科技论文统计与引文分析数据库>,实现了对论文收录作者名、址追踪.以实验数据为依据,用对比的手法介绍了每种方案的操作程序、检索特点并给出了检索效果评价指标,分析了每种检索方案的适应场合.     

一个E-Learning系统的设计与实现

提出了一个基于Internet的E-Learning(远程教学)系统的设计模型。本模型采用基于B/S的三层结构和ActiveX技术;并且在查找算法中,采用了最大匹配算法和二叉树相结合的自动分词算法,以提高网络响应速度。本模型在纵横远程教学网站中得到了实现。     

Active citizenship in schools and the community

During the 1980s the government of the time mooted the need for active citizenship which was associated with education for citizenship. The re-emergence of citizenship education as an important part of the curriculum has meant that notions underpinning the idea, including the meaning of active citizenship, are once again under scrutiny.This article examines different understandings of citizenship and how they give rise to different beliefs about what the rights and responsibilities of the citizen should be. It then discusses the present government's understandings of active citizenship and their intention to create a socially inclusive society, shifting from a rights-based paradigm of citizenship to one based on mutual obligation. It concludes by examining how those intentions might translate into the school context, drawing from recent research in three secondary schools in the United Kingdom.     

An integrative review of in-class activities that enable active learning in college science classroom settings

ABSTRACT

Engaging students in active learning is linked to positive learning outcomes. This study aims to synthesise the peer-reviewed literature about ‘active learning’ in college science classroom settings. Using the methodology of an integrative literature review, 337 articles archived in the Educational Resources Information Center (ERIC) are examined. Four categories of in-class activities emerge: (i) individual non-polling activities, (ii) in-class polling activities, (iii) whole-class discussion or activities, and (iv) in-class group activities. Examining the collection of identified in-class activities through the lens of a theoretical framework informed by constructivism and social interdependence theory, we synthesise the reviewed literature to propose the active learning strategies (ALSs) model and the instructional decisions to enable active learning (IDEAL) theory. The ALS model characterises in-class activities in terms of the degrees to which they are designed to promote (i) peer interaction and (ii) social interdependence. The IDEAL theory includes the ALS model and provides a framework for conceptualising different levels of the general concept ‘active learning’ and how these levels connect to instructional decision-making about using in-class activities. The proposed ALS model and IDEAL theory can be utilised to inform instructional decision-making and future research about active learning in college science courses.     

A comparative study of optimal linear controllers for vibration suppression

The performance enhancement of dynamic systems is accomplished by the application of active control components. Control strategies are derived to accomplish the task. Among the various control strategies, those that are designed to minimize a specified cost function while satisfying the necessary system constraints are referred to as optimal controllers. An important constraint is the amount of power and energy consumed by the control device. In this paper, the effect of optimal control strategies on the power and energy requirement of control devices is investigated.     

烯烃环丙烷化的络合催化研究

本文合成的(ipro)_3PCux,Ph_3PCux(x=cl,Br.I);(ArO)_3PCucl(ArO=Pho,O—O—Tol),Cu(-cac)_2,CuCl_2(pph_3)_2等铜络合物催化剂和 Cu(O_2CCF_3)_2,881—催化剂等铜羧酸盐催化剂.将这些催化剂用于催化四甲基乙烯和重氮乙酸乙酯的环丙烷化反应,其中881催化反应收率达84.4%,具有良好的工业应用价值.本文对环丙烷化反应的“诱导期”作了详细的研究,在环丙烷化反应过程中,加入15—环辛二烯(COD),分离得到了未见文献报道的一价铜有机络合物(I),经电子自旋共振,红外光谱、酸解后气相色谱测 COD,和分子量的测定,确定了结构.证实了反应活性中心,提出了反应的机理.     

Problem solving and engineering design,introducing bachelor students to engineering practice at K. U. Leuven

A present-day engineer has a large scientific knowledge; he is a team-player, eloquent communicator and life-long learner. At the Katholieke Universiteit Leuven, the course ‘Problem Solving and Engineering Design’ introduces engineering students from the first semester onwards into real engineering practice and teamwork. Working in small groups, the students integrate basic principles of all regular scientific courses to solve real-life engineering problems. This makes the coursework more interesting and helps the students to master the abstract theories presented in lectures. Through the increasing complexity of the assignments, the students are gradually confronted with technical and social competencies such as a systematic approach to problem solving and engineering design, teamwork, project management and communication skills. ‘Problem Solving and Engineering Design’ has been implemented in the bachelor of engineering since September 2003. The current paper describes the course objectives, the way the course is implemented to support project-based learning and the feedback obtained from the didactic team and the students.     

在VB环境下开发ActiveX文档

开发Internet应用程序的工具很多，VB提供的ActiveX文档技术就是其中的一种。本文介绍了利用ActiveX文档技术制作功能完善的ActiveX文档并生成网页的一般方法。