File and workload allocation on a local multi-access computer network: incorporating local processing and communication overhead

The paper presents an analytical model to allocate files and workload simultaneously among heterogeneous servers for a distributed database where the servers are connected by a local multi-access computer network. The allocation problem is presented in the form of a nonlinear integer programming model. The model incorporates both local processing and communication overhead. The problem is proved to be NP-complete and thus a heuristic is developed. To illustrate its suitability, the heuristic is compared with an exhaustive enumeration method for small problems and with a genetic algorithm for large problems. Computational results demonstrate that the proposed model and heuristic provide effective database designs     

航空火控动态精度检测及数据处理分析

首先针对航空火控系统的动态精度测试,分析比较了几种试验数据获取方法,指出对固定目标源测试动态精度是一种简单易行的方法。介绍了对数据的预处理方法,对预处理后的数据先根据常用的规则对火控系统的精度进行定量检测;然后采用动态数据建模方法对误差时间序列进行ARMAX模型辨识求其动态模型,再求模型在Z域的零极点分布,以及由动态模型求出各种特性函数,从而分析火控系统误差的稳定性;由规则的定量分析结果并结合动态建模后的定性分析结果就能够对火控动态精度给出更加客观深刻的检测评定结果。     

Surface characteristics of chemical conversion coating for Mg-Al alloy

The chemical conversion coating was formed on Mg alloy for low cost and harmlessness in environment by using the colloidal silica as the main component. The film formed at 298 K was thick, which was thought to be the combination of Si and O. In salt spray test, the ratio of black rust on the specimen that did not conducted chemical conversion treatment was five times or more than those of the chemical conversion treated specimen. The film of chemical conversion coating produced by alkali treatment process was thinner than the specimen produced in basic chemical conversion treatment solution.     

短炭纤维增强C/C-SiC制动材料的摩擦磨损性能

采用温压？原位反应法制备C/C-SiC复合材料,利用QDM150型摩擦试验机研究短炭纤维（SCF）长度和纤维体积分数对C/C-SiC制动材料摩擦磨损性能的影响。结果表明：C/C-SiC制动材料能够保持较高且稳定的摩擦因数;SCF的体积分数将影响C/C-SiC制动材料的摩擦磨损性能,纤维体积分数为10%时,材料具有适中的摩擦因数和较低的磨损率;SCF长度对C/C-SiC制动材料的摩擦磨损性能有显著影响,炭纤维长度为12 mm时,材料具有最佳的摩擦磨损性能。     

基于LonWorks现场总线的家庭保安系统

针对目前住宅小区报警系统在误报率、网络通信以及可扩展性等方面的局限性，采用AT89C51单片机作为微处理器及大量传感器作为信号采集装置，提出了一种基于LonWorks现场总线的家庭保安系统，此系统经模拟运行满足了低功耗要求，性能稳定且可靠性高。     

挑战机遇对策——入世后的我国会计服务业

分析了入世后，我国会计服务行业面临的历史性挑战和发展机遇，在些基础上，从五个方面阐述了我国应采取的积极有效的对策。