Sliding mode control for active magnetic bearing system with flexible rotor

This paper presents the analysis and control of active magnetic bearing (AMB) systems with a flexible rotor. A sliding mode controller design scheme is proposed to compensate for the nonlinear effects of the AMB system. A nonlinear model of the AMB system with an electromagnetic actuator and a flexible rotor is proposed to facilitate the present system analysis and controller design. This nonlinear model takes into account the dynamics of the flexible rotor, the characteristics of the nonlinear electromagnetic suspended system, and the contact force between the auxiliary bearing and the shaft. This study also considers the auto-centering control of the AMB system when subjected to disturbances and variations in the system parameters. The numerical results show that the system exhibits a periodic motion and demonstrates high accuracy and robustness when operating under sliding mode control.     

动态全参数自调整BP神经网络预测模型的建立

本文从减少干预的思想出发，提出了BP神经网络动态全参数自调整学习算法，使得隐层节点和学习速率的选取全部动态实现，实现了学习速率和网络的适应能力，最后又将改善后的BP神经网络应用到经济领域中，得到了比常规经济学模型更优的效果。     

Biological and Biochemical Potential of Sea Snake Venom and Characterization of Phospholipase A<Subscript>2</Subscript> and Anticoagulation Activity

This study is designed to isolate and purify a novel anti-clotting protein component from the venom of Enhydrina schistosa, and explore its biochemical and biological activities. The active protein was purified from the venom of E. schistosa by ion-exchange chromatography using DEAE-cellulose. The venom protein was tested by various parameters such as, proteolytic, haemolytic, phospholipase and anti-coagulant activities. 80 % purity was obtained in the final stage of purification and the purity level of venom was revealed as a single protein band of about 44 kDa in SDS-polyacrylamide electrophoresis under reducing conditions. The results showed that the Potent hemolytic activity was observed against cow, goat, chicken and human (A, B and O positive) erythrocytes. Furthermore, the clotting assays showed that the venom of E. schistosa significantly prolonged in activated partial thromboplastin time, thrombin time, and prothrombin time. Venomous enzymes which hydrolyzed casein and gelatin substrate were found in this venom protein. Gelatinolytic activity was optimal at pH 5–9 and ¹H NMR analysis of purified venom was the base line information for the structural determination. These results suggested that the E. schistosa venom holds good promise for the development of novel lead compounds for pharmacological applications in near future.     

基于RTL行为模型的测试产生及时延测试方法(英)

寄存器传输级(RTL)测试产生及时延测试是当今集成电路(IC)测试技术中亟待解决的问题和研究的热点.首先从IC逻辑测试的测试产生和IC时延测试方法这两个方面系统地综述了测试产生和时延测试领域迄今为止的主要研究成果.在RTL行为描述的测试产生方面,提出了新的RTL行为模型的描述方法:行为阶段聚类描述,并提出了基于聚类的测试产生技术.将这些技术集成到RTL级ATPG系统ATCLUB中,在提高测试产生效率及缩短测试长度方面效果显著.在IC时延测试方面,提出了一种新的可变双观测点的时延测试方法。基于该方法提出了新的时延故障诊断方法,实现和完善了可变双观测点的时延测试系统DTwDO.DTwDO提供了从时延测试到故障诊断等一系列测试工具,有效减少了测试通路数,提高了故障覆盖率,并有很高的故障定位成功率.     

Classroom and technology-supported help seeking: The need for converging research paradigms

Contributions to this special section represent advances in understanding help seeking as a self-regulated learning strategy that occurs in classrooms, during computer-mediated communications, and when using intelligent systems that provide help to improve learners’ help-seeking skills and knowledge acquisition. Collectively, the research and development contributes information relevant for all phases of the help-seeking process. My comments focus on: (a) features of technology-supported help seeking that have implications for motivation, (b) the need for increased attention to the instructional context in which technology-supported help seeking occurs, (c) a necessary convergence of classroom and technology-supported help-seeking research paradigms, and (d) reconsideration of help seeking as a social-interactive strategy.     

海德格尔的缘在分析及其方法论意义

海德格尔的缘在分析,阐明了缘在存在于与世内之物的牵念关系之中,存在于与他人共在的牵心关系之中,存在于处身情境的牵挂关系之中,并在此基础上论述了缘在与真理的关系,提出陈述的真理有赖于缘在的＂展开状态＂、＂敞开状态＂,有赖于缘在行为的＂开放状态＂。真理的本性是自由,自由是＂让存在者存在＂,这要求我们让自己在敞开状态中遭遇事物。海德格尔这些思想对于开拓人们的思维,认识世界,揭示真理,具有方法论的借鉴意义。     

视觉诗《L(a》的功能分析

人们对视觉诗《L(a》进行了多角度研究,但对该诗能被读者理解与接受的语法基础和动因,未做出解释。本文试图以功能语法中的意义潜势理论和级阶理论对此进行尝试。     

空间隐喻与位移事件结构“去VP”中的“去”

现代汉语中的"去"是一个典型的位移动词,在"去VP"结构中,这种位移通过隐喻由物理空间层面投射到心理空间、时间层面和泛方向空间等非物理空间层面,从而造成现代汉语共时层面中"去"的语法化程度的差异。     

中国就业政策评价:1998-2008

从消极就业政策到积极就业政策的转变,标志着中国政府以更为积极的姿态来处理就业问题。估算结果表明,1998-2008年,我国政府为落实就业政策累计支出6169.67亿元,其中用于落实消极就业政策的支出为4144.06亿元,落实积极就业政策的支出为2025.61亿元。实证分析发现,落实积极就业政策的支出和落实消极就业政策的支出与下岗失业人员的再就业之间存在长期稳定关系,落实积极就业政策的支出每变动1%会导致下岗失业人员的再就业数量同向变动0.27%,说明我国政府用于促进就业的支出的确对再就业工作显示出了积极作用;而落实消极就业政策的支出每变动1%将引起下岗失业人员的再就业数量反向变动1.05%,这一结果表明落实消极就业政策的支出吸引了更多的失业下岗人员加入失业保险体系,同时发挥出了一种"社会稳定器"的功能。     

作为一种教育隐喻的“绿色教育”

目前,"绿色教育"一词的基本用法还是环境教育、可持续发展教育的范式。这种用法还停留在实践策略层面,限制了自身的理论前景和实践广度。其实,"绿色教育"是一种教育隐喻。在它的隐喻空间内,潜藏着更多的喻意有待发现和发掘。根据社会以及教育发展的实际需要,以下三组选择有助于完成这项工作:第一组选择有关问题属性。通过将"绿色教育"作为一个教育隐喻来使用,可以超越已有的种种意义界限。第二组选择有关问题领域。通过这种选择,"绿色教育"实现了对环境教育、可持续发展教育的超越,侧重点由内容主题转向了价值倾向。第三组选择有关发展定位。这种选择强调教育价值倾向的"绿化",进一步提升了"绿色教育"的立意高度,使其指向对整个现代教育的改进和超越。基于这三组逐步递进的选择,"绿色教育"有可能为飞速发展的现代教育指引未来的发展方向。