Dynamic modelling and robust current control of wind-turbine driven DFIG during external AC voltage dip

INTRODUCTION Due to concerns about emissions from fossil fuels and the depletion of fossil fuel resources, re- newable energy systems are becoming a topic of great interest and investment in the world. In particular, wind energy has been the subject of much recent research and development. In order to overcome the problems associated with fixed-speed wind-turbine system and to maximize the wind energy capture, many new wind farms will employ wind turbines based on Doubly-Fed Induction Ge…     

基于Agent的远程教学系统模型建构

Agent 是人工智能和计算机软件领域中一种新兴的技术,其在远程教育中的应用具有很大的优越性。本文在分析传统的基于 Web 远程教育不足的基础上探讨了用 Agent 思想解决远程教育的问题,并设计了一个基于 Agent 的远程教学系统模型。     

WASMOD模型参数敏感性与相关性分析

对水文模型参数进行敏感性和相关性分析,可以减少率定参数的数量、提高模型运行效率,并可以为优化和改进模型结构提供依据.本文采用局部分析法和相关系数法讨论了WASMOD模型中的五个参数对目标函数的敏感程度以及参数之间的相关程度.研究发现,在黑河流域上游山区的径流模拟过程中,WASMOD模型中影响降水形态的温度参数a1对目标函数最为敏感;其次是影响地表径流的参数a6和影响融雪过程的温度参数a2;基流参数a5最不敏感.模型参数之间的相关性不是很强,这也说明,模型结构已得到很好的优化;为保证模型的模拟效果,模型参数的数量不能减少.     

More Than Just a Student Voice: Facilitating Student Leadership Development Through the Library Student Liaison Program

This article explores how the library-student liaison program at Eastern Washington University (EWU) Libraries has evolved into an opportunity for students to develop leadership skills. Originally designed to foster better communication between the EWU Libraries and students enrolled at the university, we recognized that the process of achieving established goals for the program provided a vehicle for students' leadership-skill development. To facilitate the leadership process, librarians employed the Social Change Model. Designed specifically for college students, this model engages the student to develop individual capacities to strengthen group activities that foster positive changes in the community and society.     

依托示范性实训基地提升学生就业竞争力的实践与探索——以数控技术实训基地为例

高等职业教育的根本任务是培养具有较强实践能力和职业素质的高级技能型人才,实训条件是高职院校实现技能型人才培养的薄弱环节.针对这一薄弱环节,中央财政和地方财政利用资金引导的方式,重点支持高职院校建设了一批示范性实训基地.通过对数控技术实训基地的分析,从基础平台建设、管理体系建设和校企合作建设等三个方面总结了依托示范性实训基地提升学生就业竞争力的成功经验.     

网络环境下图书储藏模式的转变

近年来,由于藏书量的增长以及校园建筑空间有限、土地昂贵等原因,促使美国一些研究图书馆仿效哈佛大学图书仓库的模式,在远离校园的地方建设图书储藏库,储藏使用率低的文献,目前已建设了几十个这样的储藏库。储藏库通常为环境可控的、高度密集式排架的书库,有独立式的,有共享式或联盟式的。一些专业人士正在探讨把地方性图书馆和储藏库、区域性储藏库按照一定的系统或线索,例如地理区域线索,组成一个网络,为数字时代印刷型文献的保存和利用提供一个理想模式。     

关于出版社的资源配置规划模型的研究

针对CUMCM2006A题出版社的资源配置问题,通过分析得出决策问题的信息流图,在此基础上建立了多目标规划模型,并用MATLAB优化工具箱函数fmincon求解模型。     

Sport education-based irregular teaching unit and students’ physical activity during school recess

Abstract

The aim of the study was to compare the effect of a Sport Education-based irregular teaching unit on the high-school students’ physical activity (PA) during school recess. A sample of 91 adolescents (45 girls) aged 13–16?years old met the exclusion criteria. The six classes were cluster-randomly assigned to the Irregular Sport Education group (Sport Education methodology with competitions in recess), Traditional Sport Education group (Sport Education methodology with competitions in Physical Education lessons), or to the control group (non-intervention). The students’ PA during school recess periods were objectively assessed by GT3X accelerometers. The results of the repeated-measures nested analysis of variance showed that the Sport Education-based irregular teaching unit significantly improved the students’ PA during recesses (p?<?0.001). The competitions phase of the Sport Education model performed at school recesses seems to be a valuable strategy for increasing students’ PA contributing to the achievement of the daily recommendations.     

我国居民消费与收入关系的实证分析

文章首先建立模型,然后利用现代计量经济学中的动态分布回归与误差修正模型,基于1996-2007年的年度数据,对我国消费与收入的关系进行实证分析,结果发现,长期来看人均收入每增加1个百分点,消费将增加0.8991个百分点,短期来看人均收入每增加1个百分点,消费将同增加0.2886个百分点,这一数值与长期关系的数值相比较而言显然较小,究其原因有预算约束,收入偏低,未来收支不确定,消费观念保守,消费环境较差,收入分配不公以及社会保障制度不健全等,因此,为了提高居民消费水平,应采取措施加以解决.     

西南民族地区乡村旅游发展模式研究

西南民族地区生态环境和民族传统文化保存较好,旅游资源丰富,在乡村旅游方面有较大的潜力和优势。近年来,随着旅游的发展,西南民族地区乡村旅游出现了环境污染、经济效益、利益分配、文化保护等一系列问题。西南民族地区乡村旅游的发展应坚持社区生态旅游,走可持续发展的道路。西南民族地区乡村旅游的发展应在保护生态环境和民族传统文化的前提下,合理开发利用旅游资源,同时旅游的发展应注重社区的权益,为当地脱贫解困,提高人们生活服务。