三相交流输电线路的电磁环境(一)

本文定量分析计算三相交流输电线路正常运行工频电、磁场对周围环境影响,以及产生电晕时对无线电接收的干扰影响。并分析在输电线路短路状态下其电磁场对周围环境的影响。     

110kV及以上高压电缆工程建设管理探讨

城市110kV及以上高压电缆的敷设里程迅速增长,在供电系统中负担起越来越重要的任务。为保证高压电缆工程的建设质量,建设者需要对电缆的技术特点、对工程施工管理有较深入的了解,采取科学的工程管理方法,才能提高高压电缆工程建设质量,满足电力系统供电可靠性的要求。     

Review of Studies on Rare Earth against Plant Disease

Agricultural application of rare earth (RE) has been generalized for several decades, and it is involved in crops, vegetables and stock raising in China. However, all the researches on RE mainly focus on the fields such as plant physiological activity, physiological and biochemical mechanism, sanitation toxicology and environmental security. Plant protection by using RE and the induced resistance of plant against diseases were summarized. The mechanism of rare earth against plant disease is highlighted, which includes following two aspects. First, RE elements can control some phytopathogen directly and reduce its virulence to host plant. Another possibility is that RE elements can affect host plant and induce the plant to produce some resistance to disease.     

The behavior and effect of rare earth CeO<Subscript>2</Subscript> on <Emphasis Type="Italic">in-situ</Emphasis> TiC/Al composite

Rare earth CeO₂ was investigated as an additive for in-situ preparation of TiC/Al composites using XD (exothermal dispersion) + casting technology. Experiment results showed that an optimum CeO₂ addition of 0.5 wt pct promotes the generation and refinement of TiC particles, prevents the formation of Al₃Ti, increases the wettability between the TiC ceramic particles and the Al matrix, and improves the mechanical properties of composite. A corresponding thermodynamic model was proposed for the mechanism.     

多媒体个人移动业务管理系统计费业务的分析与实现

随着3G移动通信网络的发展,人们对3G业务的提供,特别是多媒体移动业务提出了更高的要求。许多国际组织(如Parlay等)都提出将业务层与网络层分离,这给多媒体移动业务管理系统提出了更高的要求。文章介绍了Parlay/OSA标准规范,设计了一套适合多媒体个人移动业务的计费业务系统,并讨论了基于WebService的实现技术。     

iPMS:基于iSMS的并行移动数据处理系统

移动计算已经成为信息技术新的研究热点,如何通过移动网络有效接入互联网是其中的关键技术之一。首先对iSMS结构的特点进行了分析,认为iSMS在支持大量客户时会造成拥挤。针对该问题,论文研究并设计了一种多移动终端并行的移动数据处理系统,该系统具有良好的扩充性。然后作者给出了详细的执行流程和实现原理,并应用在北京大学移动计算平台LDPM1.0中。最后,作者对iPMS进行了性能评价,并给出了系统运行的试验结果,对其中存在的问题以及今后的工作进行了展望。     

用混合遗传算法进行工程智能优化的方法研究

智能优化是从诸多新兴学科衍生出来的前沿科学,遗传算法是智能优化的重要工具之一。该文针对遗传算法存在的不足,用混合遗传算法解决了工程智能优化问题,弥补了遗传算法存在的缺陷,在工程实践中证明了混合遗传算法在性能和质量方面的优越性。     

机器人避开多随机障碍物的路径规划方法

该文充分考虑了运动障碍物的随机性及其运动的非线型性,研究了随机运动障碍物的位置分布规律,并结合随机运动障碍物具有惯性的特点,提出了对机器人运动路线进行动态规划的逐步判别方法。计算机仿真表明,该算法是一种正确、高效、实用的算法,对机器人绕过随机运动障碍物具有参考价值。     

基于状态检测的TCP包过滤在Linux下的实现方法

该文主要介绍了在Linux2.4内核下基于状态转换和检测的TCP包过滤的实现方法。通过对传统全状态包过滤防火墙的改进,增加了状态转换和连接序号检查,增强了防火墙的安全性。通过日志记录异常状况,系统管理员可以采用相应的措施防止潜在的攻击。     

Investigation of the firing voltage in a shadow‐mask PDP

Abstract— A numerical method was used to investigate the firing characteristics of the discharge cell in an AC shadow‐mask PDP (SM‐PDP). The firing voltages for the various discharge paths in the addressing and sustaining periods were calculated, and the effects of the metal barrier rib and the dielectric layer in the discharge cell on the firing characteristics were studied. Furthermore, the advantages of the SM‐PDP in terms of the firing characteristics will be discussed.