汽轮机回热系统给水焓升的最优分配

从汽轮机回热系统的实际情况出发，运用非线性规划理论和计算机技术，解决了给水焓升设计中的最优分配问题。结合具体实例，针对国产200MW汽轮机回热系统给水焓升的分配进行了说明。     

多部件设备维修问题研究及遗传算法求解

合理组织设备维修，缩短设备维修时间是生产运营管理的一个重要环节。本文探讨了多部件设备维修的有效组织问题。考虑到维修工人对拆分后设备的不同部分具有不同的维修效率，提出了一种基于维修时间优化的决策方法，将其与经典指派方法进行了比较；进一步地，对这一NP-hard问题设计了遗传算法，通过数值例子讨论了其求解有效性。     

陈村水电站水调自动化系统的建设及应用

陈村水电站在电网的调峰、调频中起着重要的作用,同时水库也面临着防洪、灌溉等任务。为改善陈村水库防洪调度手段,充分挖掘水库调度潜力,提高发电和防洪效益,在原有洪水预报系统的基础上,建立了陈村电厂水库调度自动化系统。该系统集成了洪水预报、水库调度、发电优化、数据整编等各方面功能,并可进行梯级电站联合调度。     

考虑电气价因素的压气站运行优化模型研究

针对压气站运行优化模型，引入了两个开关型变量：压气站开关变量和压缩机开关变量：同时还引入了考虑提供单位功率所需的能耗量两个变量。其优点是考虑了压气站越站和站内压缩机停机的情形，而且还直接引入与价格相关的变量，使得模型在运行优化的结果上更能体现某种方案的经济性，这对于管道运行商来说，更具有直观性。     

生产调度决策优化系统Orion

炼油化工企业的生产装置是一个连续的、有机的整体，调度生产作业计划是确保生产优化、平稳、有序的基础。先介绍中国国内生产调度计划软件的发展情况，接着论述中国石化股份公司长岭分公司引进AspenTech公司的生产调度系统Aspen Orion及二次开发过程，就其技术与经验以飨同行。     

遗传算法的改进及其在电力系统无功优化中的应用

针对无功优化的动态、多目标、多约束以及非线性特点,提出了基于简单遗传算法的改进算法,在简单遗传算法的基础上,添加了自适应控制和适应度排序思想,并对算法终止准则进行了改进。以IEEE14节点标准测试系统为例对该算法进行了有效性验证。仿真结果表明,该方法对电力系统的无功优化效果良好。     

Analysis and Optimization of the Energy Efficiency in the 802.11 DCF

This paper introduces an analytical model to investigate the energy efficiency of the IEEE 802.11 distributed coordinated function (DCF). This model not only accounts for the number of contending nodes, the contention window, but also the packet size, and the channel condition. Based on this model, we identify the tradeoff in choosing optimum parameters to optimize the energy efficiency of DCF in the error-prone environment. The effects of contention window and packet size on the energy efficiency are examined and compared for both DCF basic scheme and DCF with four-way handshaking. The maximum energy efficiency can be obtained by combining both the optimal packet size and optimal contention window. To validate our analysis, we have done extensive simulations in ns-2, and simulation results seem to match well with the presented analytical results. The Ohio Board of Regents Doctoral Enhancements Funds and the National Science Foundation under Grant CCR 0113361 have supported this work. Xiaodong Wang received his B.S. degree in communication engineering from Beijing Information Technical Institute of China in 1995, and his M.S. degree in electric engineering from Beijing University of Aeronautics and Astronautics of China in 1998. He joined China Telecom in 1998 where he worked on communication protocols for telecommunication. From June 2000 to July 2002, he worked on GSM base station software development at Bell-labs China, Beijing, China. Currently he is a Ph.D. student in Computer Engineering at University of Cincinnati. His research activities include wireless MAC protocols, energy saving for wireless sensor networks. He is a student member of the IEEE. Jun Yin received the BS degree in automatic control from Dalian Railway Institute of China in 1997, and the MS degree in flight control from Beijing University of Aeronautics and Astronautics of China in 2001. Since 2001 she has been a Ph.D. student in the OBR Research Center for Distributed and Mobile Computing at the University of Cincinnati. Her research interests include performance evaluation of 802.11 MAC protocol, wireless ad hoc networks and sensor networks. She is a student member of the IEEE. Dharma P.Agrawal IEEE Fellow, 1987; ACM Fellow, 1998; AAAS Fellow, 2003 Dr. Agrawal is the Ohio Board of Regents Distinguished Professor of Computer Science and Computer Engineering in the department of Electrical and Computer Engineering and Computer Science, University of Cincinnati, OH. He has been a faculty member at Wayne State University, (1977–1982) and North Carolina State University (1982–1998). He has been a consultant to the General Dynamics Land Systems Division, Battelle, Inc., and the U. S. Army. He has held visiting appointment at AIRMICS, Atlanta, GA, and the AT&T Advanced Communications Laboratory, Whippany, NJ. He has published a number of papers in the areas of Parallel System Architecture, Multi computer Networks, Routing Techniques, Parallelism Detection and Scheduling Techniques, Reliability of Real-Time Distributed Systems, Modeling of C-MOS Circuits, and Computer Arithmetic. His recent research interest includes energy efficient routing, information retrieval, and secured communication in ad hoc and sensor networks, effective handoff handling and multicasting in integrated wireless networks, interference analysis in piconets and routing in scatternet, use of smart directional antennas (multibeam) for enhanced QoS, Scheduling of periodic real-time applications and automatic load balancing in heterogeneous workstation environment. He has four approved patents and three patent filings in the area of wireless cellular networks.     

DB2数据库查询优化策略

数据库的查询优化是改善应用程序性能的重要手段。通过分析IBM DB2数据库系统的最优化处理器的工作原理,对查询性能影响较大的统计信息更新、索引建立、SQL查询语句构造3个方面提出具体优化建议。建立了一套完整的测试方案,对每一条优化建议都使用具体SQL语句进行严格的验证。开发者要注意分析查询语句的时间开销和空间开销,才能写出较优的查询语句。     

左江水利枢纽工程施工导流设计的优化

导流工程在施工条件改变时,应根据工程的实际情况进行相应的调整及优化,以达到节省导流工程投资、满足主体工程施工要求的目的;介绍了左江水利枢纽工程施工导流设计的优化情况。     

Schubspannungsbomben in Faserverbunden

Shear Bombs in Fibre Composites Despite an optimum external shape non‐load adapted internal fibre orientation can lead to the formation of shear cracks where crossing tension‐compression principal stress trajectories create localized shear peaks. Trees are subject to those failure because they cannot re‐arrange their fibres after wood formation. Bones can adjust their micro‐structure to changing load conditions and in this way can better control shear failure. The engineer working with fibre composites should be alert to avoid fibre arrangements not following the force flow. Localized shear zones may also form near notches similar to normal notch stresses, however they are not always situated at the contour line of the notch.