天然气管网输配气量优化研究

天然气管网系统管理部门为了明确天然气管网的输气能力和提高天然气管网的利用率，需要对天然气管网系统的输配气量进行优化。为此，以天然气管网系统的最大流量为目标函数，同时考虑了管道强度、节点压力和流量限制等约束条件，建立了天然气管网输配气量优化的数学模型。在研究遗传算法和模拟退火算法的基础上，提出了一种由二者结合构成的具有全域搜索、快速收敛和鲁棒性强等特点的混合遗传算法。结合实例，采用这一新算法求解了天然气管网输配气量优化的数学模型。实例优化结果表明，所建立的数学模型和采用的混合遗传算法是可行和有效的，能够对天然气管网系统输配气量的调度运行起到指导作用。     

RMT1-250转换开关用电接触材料

铜铬锆合金是一种形变热处理材料，兼具了铜铬合金和铜锆合金的各种优良性能，经过时效处理的铜铬锆合金，与铜相比，高温强度有很大的改善，而且具有较高的导电率。所以铜铬锆合金广泛应用于电焊机、低压电器等行业。根据对铜铬锆成分的适当调整，可用作为电焊机电极，低压电器触桥、短路环等各种电接触材料。铜铬锆合金用于RMT1－250转换开关，接近于触桥材料的应用，但使用的条件更苛刻一些，要承受部分电弧的侵蚀和由此产生的高温，因此对材料要求具有良好的导电导热性和更高的高温强度。     

技术攻关提高成材率

介绍了广钢集团高速线材生产线的生产和工艺概况，分析了成材率的影响因素，阐述了技术攻关提高成材率所采取的措施和取得的良好效果及经济效益。     

金沙江防洪(库容)规划的探讨

在分析长江灾害洪水特征的基础上，全面深入地研究了全沙江水库的防洪库客、防洪目标、防洪特点和调度原则，并对防洪库容的作用进行了估算和分析。从多方面比较了虎跳峡高坝方案与低坝方案，结果表明：高坝方案的效益明显高于低坝方案，而两者所需付出的代价相差不大。     

250W带功率因数校正整流电源模块的研制

功率因数校正技术越来越成为电源行业研究的热点。文中介绍了适用于雷达等设备的250W带功率因数校正整流电源模块的设计，分析了其中升压电感器设计、主开关管保护、控制电路消振、散热设计和表面贴装等关键技术，完成了实验研究，获得了满意的试验结果。     

大功率开关电源的设计与实现

介绍了开关电源设计中需要考虑的几个基本问题,包括频率的确定、最大占孔比Dm的确定、逆变变压器的设计和开关功率管的选择,并以一种1 kW的PWM大功率半桥式开关电源为例,详细介绍实际的开关电源设计方案,并给出了实验结果.     

Using Bandwidth-Space Partitioning to Improve Cell Coverage and Near-Far Unfair Access Problem in a Noise-Limited CDMA Cellular Network

This paper concerns CDMA cellular networks equipped with conventional matched filter receivers. For this type of cellular networks, two problems exist. One is the inverse relationship between the coverage and capacity, and the other one is the near-far unfair access problem. To resolve these two problems, a bandwidth-space partitioning technique is adopted. Several admission control schemes based on the bandwidth-space partitioning technique are proposed, and their performances are evaluated based on the simulation.Shih-Tsung Yang received his B.S. (1989) and M.S. (1991) degrees in electrical engineering from the National Taiwan University, and Ph.D. (1999) degree in electrical and computer engineering from University of Maryland, College Park.From 1999 to 2000, he was with SBC Technology Resourtces, Inc. where he was involved in the network architecture design for the ATM based networks. From November 2000 to May 2003, he was with Transilica/Microtune where he was involved in the design of Baseband and RF for the wireless communications. Since May 2003, Dr. Yang is now with Genesys Logic, Inc. where he is responsible for the baseband design of the WLAN and Ethernet.Dr. Yang’s research interests are in the area of Digital Communications, Communication networks and signal processing. E-mail: thomas.yang@genesyslogic.com.twAnthony Ephremides received his B.S. degree from the National Technical University of Athens (1967), and M.S. (1969) and Ph.D. (1971) degrees from Princeton University, all in Electrical Engineering. He has been at the University of Maryland since 1971, and currently holds a joint appointment as Professor in the Electrical Engineering Department and in the Institute of Systems Research (ISR) of which he is a founding member. He is co-founder of the NASA Center for Commercial Development of Space on Hybrid and Satellite Communications Networks established in 1991 at Maryland as an off-shoot of the ISR. He served as Co-Director of that Center from 1991 to 1994.He was a Visiting Professor in 1978 at the National Technical University in Athenas, Greece, and in 1979 at the EECS Department of the University of California, Berkeley, and at INRIA, France. During 1985-1986 he was on leave at MIT and ETH in Zurich, Switzerland. He was the General Chairman of the 1986 IEEE Conference on Decision and Control in Athens, Greece and of the 1991 IEEE International Symposium on Information Theory in Budapest, Hungary. He also organized two workshops on Information theory in 1984 (Hot Springs, VA) and in 1999 (Metsovo, Greece). He was the Technical Program Co-Chair of the IEEE INFOCOM in New York City in 1999 and of the IEEE International Symposium on Information theory in Sorrento, Italy in 2000. He has also been the Director of the Fairchild Scholars and Doctoral Fellows Program, an academic and research partnership program in Satellite Communications between Fairchild Industries and the University of Maryland. He won the IEEE Donald E. Fink Prize Paper Award (1992) and he was the first recipient of the Sigmobile Award of the ACM (Association of Computer Machinery) for contributions to wireless communications in 1997. He has been the President of the Information Theory Society of the IEEE (1987) and has served on its Board of Governors almost continuously from 1981 until the present. He was elected to the Board of Directors of the IEEE in 1989 and 1990. Dr. Ephremides has authored or co-authored over 100 technical journal papers and 300 technical conference presentations. He has also contributed chapters to several books and edited numerous special issues of scientific journals. He has also won awards from the Maryland Office of Technology Liaison for the commercialization of products and ideas stemming from his research. He has served on the Editorial Boards of the IEEE Transactions on Automatic Control, IEEE Transactions on Information theory, the Journal of Wireless Networks, and the International Journal of Satellite Communications.He has been the Dissertation Supervisor of over twenty Ph.D. students who now hold prominent positions in academia, industry, and research labs. He is the founder and President of Pontos, Inc., a Maryland company that provides technical consulting services, since 1980.Dr. Ephremides’ interests are in the areas of communication theory, communication systems and networks, queueing systems, signal processing, and satellite communications. His research has been continuously supported since 1971 by NSF, NASA, ONR, ARL, NRL, NSA, and Industry. E-mail: tony@eng.umd.edu     

L-乳酸和聚乳酸的研究进展

综述了乳酸发酵和提取工艺以及聚乳酸的合成进展,分析了L-乳酸及合成聚乳酸两种产品的市场前景,对进一步的技术开发提出了建议。     

氧化铝熟料单筒冷却机节能技术改造

本对影响氧化铝熟料单筒冷却机冷却效率的因素进行了分析，并提出了相应的节能技术改造措施，取得了明显的节能效益。     

芳烃抽提装置技术改造

由于中国石化锦西石化分公司600kt／a连续重整装置的建设，芳烃抽提装置的原料由原来的脱戊烷油变为Ce组分。为此，对抽余油水洗塔和芳烃分离部分的苯塔塔盘，以及苯塔塔顶和塔底抽出部分进行了改造，更换部分机泵和增加变频泵，并将常规仪表改为DCS控制。改造后装置实现一次开车成功，生产出合格产品。抽余油中总芳烃含量小于0．1％，苯回收率达到99%以上。