分布式证书系统的研究与实现

分析了Ｉｎｔｅｒｎｅｔ信息安全的特点,对比借鉴目前国际上几种主要的证书系统,提出了一种分布式的证书系统模型和实现方案。     

Design of a 2.5～14.5GHz distributed power amplifier

The operation principle of distributed amplifiers and the impedance characteristic of artificial transmission lines (ATLs) are analyzed, and a distributed power amplifier consisting of three gain cells is designed and fabricated by 0.18μm complementary metal oxide semiconductor (CMOS) technology. The peaking inductor is used to enhance the gain and the reverse isolation of the amplifier in high frequency. The termination loads of ATLs are increased and the values of on-chip inductors are optimized to provide good impedance matching, while improving the output power and efficiency. Measured results show that the amplifier has a 3dB bandwidth of 12GHz (2.5～14.5GHz) and provides an average forward gain of 9.8dB from 3 to 14GHz with a gain flatness of ±1dB. In the desired band, the output power at 1dB gain compression point (P_1dB) is from 4.3 to 10.3dBm while the power added efficiency (PAE) is from 1.7％ to 6.9％.     

基于JTA的跨数据库分布式事务的实现

应用系统开发中,事务是一个不可或缺的组件模型,保证了用户操作的ACID属性。对于跨数据库的大型应用,必须使用分布式事务。JTA为J2EE平台提供了分布式事务服务,讨论JTA的体系架构,通过示例介绍其实现机制。     

分布式能源系统及其运行特性分析

介绍了日本某学术研究都市的分布式能源系统所采用的发电技术和余热利用系统,并对此系统的历年运行数据进行了分析.通过分析发现,燃料电池的余热利用效果不理想,其综合能源利用效率低;而燃气内燃机的余热利用较好,综合能源利用效率达到60%以上.因此提高整个系统的余热利用率是该系统优化运行的重要课题.     

Combination of interference alignment and beamforming in cellular networks

In this paper, we propose two joint transmit-receive iterative algorithms without the cooperation between different base stations based on the idea of interference alignment (IA) to improve the throughput of relay backhaul links in cellular networks for the case of imperfect channel knowledge,which can be implemented with small changes to existing TD-LTE standards. Unlike the previous interference alignment algorithms’ only reducing the sum interference to the other receivers at the transmitter or the sum received Multi-user interference (MUI) at the receiver, our algorithm shapes the transmission of each data stream at transmitters in order not only to minimize interference to the other users, but also to minimize the interference between different streams objected to the same user, suppressing the MUI and Multi-stream interference (MSI) at receivers. The proposed algorithm I is to maximize the SINR at receivers. But the complexity is relatively high. Algorithm II only needs linear operations and sacrifices a little performance for much lower complexity compared to the Maximize SINR iterative algorithm which needs the inversion operation of matrix. It is also proved that the algorithm converges monotonically. The simulation results show that the techniques have considerable performance gain compared with the previous algorithms. Further research about power allocation is also discussed.     

结构化分析与设计技术——一种软件工程方法论

本文通过开发大型软件系统的六个阶段,阐述一种进行功能分析和系统设计的综合方法论,包括它的技术和应用这些技术的过程,并结合程控电话交换系统的实例,作了探讨.表明了软件工程不仅是一种需要继续发展的理论,而且已经成为一种工程实践的活动.     

数值模拟地震形变力场

本文提出用有限元方法和按距离加权平均法数值构造地震形变力场,比较了这两种方法的优点和存在的主要问题,并结合计算机口形学的技术描述组成具体实用的系统．     

自动电压控制(AVC)在DCS中的实现与应用

自动电压控制(AVC)是电网安全、优质和经济运行的重要手段.针对现有的无AVC功能的励磁系统,通过分散控制系统(DCS)中的软硬件,接受电网调度能量管理系统(EMS)来的电压指令实现相关的调节逻辑,输出脉冲指令来增减励磁电流,改变发电机无功,从而实现电网自动电压控制.这一方法不仅有效降低电网电压波动幅度和频率,而且简单实用、节约成本,减轻了操作强度.     

湖北电网输电线路大负荷试验研究

在2007年夏季负荷高峰期间对湖北省电力公司的两条220kV卡口线路高楼线、郭楼线进行了大负荷考核试验,验证了提高线路输送能力理论研究的结果,同时积累了宝贵的经验,可以在今后类似的试验中加以推广。     

济钢工业供排水管理上存在的问题及其对策

介绍了济钢供排水现状,根据存在的节水意识淡薄,管理体系不完善以及部分计量仪表和设施失修等问题,认为必须强化节水意识,完善节水管理,并对重点外排水进行控制等措施,才能减少吨钢耗新水量,提高水资源利用率。