三轴转台中框双马达驱动控制技术研究

在对同步技术及同步误差产生原因分析的基础上，提出了共反馈同步误差模糊校正系统方案，并对模糊控制器进行了设计及修正。着重分析了仿真转台电液位置伺服系统控制策略，最后通过实验来验证所采用的控制策略是提高控制精度及减小同步误差的有效方法。     

Design, analysis, and implementation of an agent driven pull-based distributed video-on-demand system

The problem of employing multiple servers to serve a pool of clients on a network based multimedia service is addressed. We have designed and practically implemented a prototype system employing multiple servers to render a long duration movie to the customers. We have employed a multiple server retrieval strategy proposed in the literature [39] to realize this system. In the system, server coordination, client behavior and service facilities are completely controlled by an Agent based approach in which we have used the recent Jini technology. Several issues, ranging from data retrieval from individual server, behavior of the underlying network infrastructure, to client management and resource (client buffers) management, are considered in this implementation. We describe in detail our experiences in this complete design process of every module in the software architecture, its purpose, and working style. Further, the system is shown to be robust amidst unpredictable failures, i.e., in the event of server crashes. The load balancing capability is built-in as a safe guard measure to assure a continuous presentation. We present a comprehensive discussion on the software architecture to realize this working system and present our experiences. A system comprising a series of Pentium III PCs on a fast Ethernet network is built as a test-bed. Through this prototype, a wider scope of research challenges ahead are highlighted as possible extensions. Bharadwaj Veeravalli Member, IEEE & IEEE-CS, received his BSc in Physics, from Madurai-Kamaraj Uiversity, India in 1987, Master's in Electrical Communication Engineering from Indian Institute of Science, Bangalore, India in 1991 and PhD from Department of Aerospace Engineering, Indian Institute of Science, Bangalore, India in 1994. He did his post-doctoral research in the Department of Computer Science, Concordia University, Montreal, Canada, in 1996. He is currently with the Department of Electrical and Computer Engineering, Computer and Information Engineering (CIE) division, at The National University of Singapore, Singapore, as a tenured Associate Professor. His main stream research interests include, Multiprocessor systems, Cluster/Grid computing, Scheduling in parallel and distributed systems, Bioinformatics & Computational Biology, and Multimedia computing. He is one of the earliest researchers in the field of divisible load theory. He has published over 75 papers in high-quality International Journals and Conferences. He had secured several externally funded projects. He has co-authored three research monographs in the areas of Parallel and Distributed Systems, Distributed Databases, and Multimedia systems, in the years 1996, 2003, and 2005, respectively. He had guest edited a special issue on Cluster/Grid Computing for IJCA, USA journal in 2004. He has been recently invited to contribute to Multimedia Encyclopedia, Kluwer Academic Publishers, 2005. He is currently serving the Editorial Board of IEEE Transactions on Computers, IEEE Transactions on SMC-A and International Journal of Computers & Applications, USA, as an Associate Editor. He had served as a program committee member and as a session chair in several International Conferences. Long Chen received the B.E. degree in Electrical Engineering and M.E. degree in Electrical Engineering from the Northwestern Polytechnic University, P. R. China, in 1998 and 2001, respectively, and the M.E. degree in Computer Engineering from the National University of Singapore, Singapore, in 2004. He is currently a Ph.D. candidate at the Department of Electrical and Computer Engineering, the University of Delaware, United States. His research interests include multimedia systems, distributed system, network security, and computer architecture.     

基于MDA数据库开发方法研究

随着数据库规模的不断扩大,传统的基于E-R模型的数据库设计方法显得过于繁琐,且不能自动适应数据库平台的变更.为了解决上述问题,提出了利用模型驱动体系(MDA)开发数据库的新方法.介绍了MDA的基本概念、基于MDA开发过程等;重点研究了基于UML数据库平台无关模型(PIM)、平台相关模型(PSM)等模型的建模方法以及基于查询、视图和变换语言(QVT)的模型变换方法;并借助MDA工具,将该方法成功运用于实际的数据库开发活动之中.实践证明,基于MDA数据库开发方法是规范数据库开发过程、提高数据库开发效率和可重用性的有效途径.     

多时空通道中子注量率密度数据采集系统方案设计

介绍了用在加速器驱动核能系统(ADS)次临界原理验证装置上的微机化多时空通道中子注量率密度数据采集系统设计方案．该数据采集系统用于采集多个空间位置的中子注量率密度水平随时间变化的数据。     

智能装备故障预测与健康管理系统研究

针对智能装备预测性维护存在的智能化和网络化程度不高、物理模型建模困难等 问题,研究了数据驱动的智能装备远程故障预测与健康管理系统(PHM)的实施框架、关键技术 和系统开发方法。具体阐述了数据驱动 PHM 系统的运行模式,在此基础上分析了 PHM 系统的 软件架构和关键技术,首先利用 EEMD 对原始信号进行降噪和重构,将重构后的信号作为输入 建立基于 RBF 神经网络的故障诊断模型;然后采用动态神经网络建立基于时间序列的故障预测 模型,并建立基于故障阈值的故障报警机制;最后利用混合编程和网络化开发技术开发了数据 驱动的远程 PHM 系统。实际应用结果表明,该系统能以较高效率完成故障诊断、故障预测等 核心功能,具有良好的实用性。     

文化整体性视角下北岳的移祀及两山的景观 关联性探究

北岳,作为中国古代北方疆域的地理坐标,文化地 位显赫且移祀历史独特。为研究北岳的历史演变历程,通过历 史文献收集、舆图考证及实地调研的研究方法,考证了自五代 至清,古北岳岳庙下移、浑源北岳说萌芽、古今北岳封祀并存 等驱动北岳移祀的转折性事件。研究发现,在文化整体性视角 下,北岳的移祀受到疆域格局扩张、王朝地理推动、军事信仰 转移等制度文化影响,亦受到北岳恒山地区农业经济发展的影 响,以及精神文化层面社会情绪的助力。北岳的移祀受到官方 和民众的共同推动,体现了北岳在宏观人文构想下地理空间与 国家秩序空间中定位的演变,催生了具有关联性特征的自然人 文景观。文化整体性视角下,北岳作为一个文化符号,不仅整 合了移祀前后两山具有历时性特征的风景表征,更因移祀所映 射的北岳文化推动着风景名胜的保护与传承。     

修正的潜在结构正交投影的过程监控

近年来,质量相关的故障诊断受到学界的广泛关注。目前存在多种基于后处理的故障诊断算法,但是,进一步的研究发现,当质量无关的故障幅度增强时,这些后处理算法会逐渐失去功能,除此之外,后处理算法在实践中会产生很大的计算量。为了进一步解决上述算法的弊端,采取一种预处理、建模、后处理的结构,并提出修正的潜在结构正交投影算法。对比之前的算法,该方法对质量相关的故障更具实用性,同时减少了模型所需潜在变量的数目,与之前算法相比,计算量更低,数值示例和田纳西-伊士曼过程用来验证该方法的有效性。     

动平衡机气体驱动研究

设计了一种动平衡机驱动装置,采用气体作为动力源驱动涡轮叶片转子,为测量提供稳定的转速,来确保动平衡测量的精度.阐明驱动原理和相应的结构,分析了流量与转速的关系,建立了流量与转速的数学模型,并对比分析了气体驱动与带圈驱动的转速波动和两种驱动在不同试重下不平衡量的误差.根据实验数据得出,在一定流量的范围内,气体驱动的转速波...     

参数化CAD-CAPP系统技术的研究与应用

针对现代制造企业对信息集成的需求,研究了参数化CAD/CAPP系统的原理及相关技术.利用相似性原理、可重用性原理、实例推理技术、设计知识库技术、参数化技术开发了参数化CAD模块.开发了基于设计知识数据驱动、工艺知识约束修改典型工艺模板的派生式参数化CAPP模块.并建立了巷道式双立柱堆垛机参数化CAD/CAPP系统,实现...     

ACCESS数据库应用课程教学方法的探索

本文对目前高校非计算机专业Access数据库应用教学方法进行了总结。结合作者多年的教学经验,本文从课堂教学和实践教学两方面对该课程的教学方法进行了探索,提出了采用案例教学法进行授课,不仅可以提高教学质量,而且可以激发学生学习兴趣,培养学生自主学习、创造思维的能力。