解线性方程组的一种预处理方法

用迭代法求解线性代数方程组时,由于收敛条件较严,只能对一些特殊矩阵(如对角占优、对称正定矩阵等)构造迭代公式.针对一般的线性代数方程组,本文采用预处理的手段. Gauss-Seidel迭代法做出了改进,可以将Gauss-Seidel迭代法不收敛的线性方程组,选取适当的预处理因子,使得线性方程组预处理迭代收敛.     

ON THE CONVERGENCE DOMAIN OF THEMATRIX MULTISPLITTING RELAXATION METHODS FOR LINEAR SYSTEMS

The convergence of the parallel matrix multisplitting relaxation methods presented by Wang (Linear Algebra and Its Applications 154/156 (1991) 473-486) is further investigated.The investigations show that these relaxation methods really have considerably larger convergence domains.     

THE CAPACITY CALCULATION FOR CDMA MOBILE SATELLITE COMMUNICATION SYSTEM

On the basis of considering downlink power flux density limit, shadowing effect frequency reuse in different systems and adjoining beams of same system, adopting voice activity and polarization isolation techniques, the capacity of CDMA mobile satellite communication system at different downlink power flux density limit modes, channel spread bandwidth and mobile user's quality factor of receiving system(G/T) are analysed and calculated, and compared with the ones of TDMA and FDMA. The conclusions are given at the end of this paper.     

高能固体激光系统设计及性能评估

近年来高能固体激光器研究及小型电源技术取得了很大的进展,使得利用电源提供能量的高能激光器在近期的应用成为可望实现的目标.但由于高能激光系统设计复杂,且造价高,需要在激光系统设计制造之前对系统性价比进行优化,并对系统性能进行评估.其中选择激光器主要考虑激光波长位于大气窗口,使得经大气传输后激光能量衰减尽可能小;光学系统设计主要考虑物理光学效应的限制及增加自适应光学系统对大气效应引起的光束畸变进行校正.大气传输与补偿模拟程序可对包括高能激光系统、激光大气传输效应等进行全程数值模拟,从而可在高能激光系统设计制造之前对系统性能进行评估,或对现有高能激光系统性能及其对靶目标的损伤效果进行评估.     

一种基于动态模糊综合评判的故障预测新方法

针对影响装备寿命的许多故障因素和故障关系具有复杂性、非确定性以及时变性的特点，指出了传统模糊综合评判方法的不足，提出了基于动态模糊综合评判的故障预测方法，给出了动态权重矩阵和动态隶属度的确定方法，以火炮反后坐装置为例对评判过程予以说明，证明了该方法的有效性和实用性。并将模糊综合评判与产生式规则相融合，利用复合推理机制提高预测结果的准确性。     

Comparison of various automatic means for measuring mean fundamental frequency

The purpose of this paper was to evaluate the reliability of, and agreement among, six speech analysis systems in the determination of fundamental frequency. Five male and five female speakers provided oral reading and sustained vowel samples for analysis. Each sample was analyzed five times by each system. The results indicated high reliability for all of the systems for both sexes and both utterance types. Agreement among the systems was high for the male sustained vowels and the female oral reading samples. In contrast, poor agreement occurred among the systems for the male oral reading samples and the female sustained vowels. The findings indicate that the output of these automatic methods tends to be consistent over repeated trials within the systems in their extraction of fundamental frequency; however, agreement among these systems varies.     

Weighted singularly perturbed hybrid stochastic systems

In this paper weighted singularly perturbed hybrid stochastic systems are discussed. Under some reasonable assumptions, it is shown that there exists a uniformly δ-optimal policy when the perturbation is sufficiently small.Received: December 2005 / Revised: March 2005This author was supported partially by National Natural Science Foundation of China under grant 60274050, 70221001 and 70328001.This author was supported partially by Australia Research Council Grant #A49532206.     

COP8 Flash单片机在开关电源嵌入式监控系统中的应用

介绍单片机嵌入式监控系统由间存型单片机COP8CDR9、并行A/D、串行D/A、并行实时时钟、16×2字符型液晶显示模块、4键(上健、下键、菜单键、确认键)和隔离接口电路等组成。该系统能够测量和显示开关电源的输出电压、电流和关键点的温度值,能够调节榆出电压、电流值,并能够通过RS232与PC机通讯,通过RS485与其他监控系统通讯。它也能够用快闪存储器构成的虚拟EEPROM记录开关电源的故障信息。实验结果表明,COP8 flash型单片机在监控系统应用方面具有较大的应用价值。     

中国电信服务业的市场化演进

2002年以中国电信一分为二为主要标志的电信体制改革所形成的“5 1”格局,并不表明中国电信业的改革已经到位。电信改革的主要目标之一是市场化,而现在的情况离市场化的要求还有很大的距离。中国电信运营业目前的产权结构和资本组成单一,很难与跨国电信企业竞争。对电信业内的垄断要做客观评价。中国电信业要有自己的龙头企业,要从行政垄断转变到市场垄断,迎接大型跨国公司的挑战。     

与光纤通信系统设计有关的几个问题(下)

从工作波段、系统单元的参数、系统／网络的拓扑、系统设计方法、系统升级考虑，光选路等几个方面，介绍了在光传送网络系统设计中应考虑的几个主要问题。