便携式防空导弹的改进与发展

概括分析了国外几种主要便携式防空导弹的系列化改进发展。     

文化现象与外语教学

语言体现文化,文化蕴于语言之中.研究文化与语言的关系,把语言中的种种文化观象,应用于外语教学,可加深学生对语言的理解,提高外语教学效果.     

论新世纪教师的教育观

新世纪要求教师必须具有素质教育观,以教育目的衡量教育质量,以启发式、讨论式教学为主,以学生为教学的主体,以教师为教学的主导的观念来指导和实施学校的教育教学工作,以达到培养出适应社会发展要求的新人才之目的.     

高校科技人才培养环境设计的原则

高校科技人才现状不容乐观,优化高校科技人才培养环境应遵循三个基本原则:平等竞争激励原则、团体文化原则和能级原则.     

论西北边疆地区综合型大学科技发展策略

西北边疆地区综合型大学在科技发展中存在着一些问题,师资结构不合理,基础设施、研究条件相对落后.构建良好的科研体系,强化科技计划管理,为高校科技创新和发展提供动力.     

运用类比联想尝试启研式教学

运用类比推理和联想的方法,解决几个初等几何问题,揭示发现数学问题的方法--合情推理,培养师范生研究数学及数学教学的意识和能力.     

DIS系统中实时通讯技术的研究

针对DIS系统实时通讯的要求 ,以UDP通讯协议为基础 ,结合采用多线程技术 ,给出了一种实时通讯方法 .经模拟试验表明该方法在WindowsNT环境下是有效的 .     

Estimating failure time distribution and its parameters based on intermediate data from a Wiener degradation model

Instead of measuring a Wiener degradation or performance process at predetermined time points to track degradation or performance of a product for estimating its lifetime, we propose to obtain the first‐passage times of the process over certain nonfailure thresholds. Based on only these intermediate data, we obtain the uniformly minimum variance unbiased estimator and uniformly most accurate confidence interval for the mean lifetime. For estimating the lifetime distribution function, we propose a modified maximum likelihood estimator and a new estimator and prove that, by increasing the sample size of the intermediate data, these estimators and the above‐mentioned estimator of the mean lifetime can achieve the same levels of accuracy as the estimators assuming one has failure times. Thus, our method of using only intermediate data is useful for highly reliable products when their failure times are difficult to obtain. Furthermore, we show that the proposed new estimator of the lifetime distribution function is more accurate than the standard and modified maximum likelihood estimators. We also obtain approximate confidence intervals for the lifetime distribution function and its percentiles. Finally, we use light‐emitting diodes as an example to illustrate our method and demonstrate how to validate the Wiener assumption during the testing. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

The building evacuation problem with shared information

In this article, the Building Evacuation Problem with Shared Information (BEPSI) is formulated as a mixed integer linear program, where the objective is to determine the set of routes along which to send evacuees (supply) from multiple locations throughout a building (sources) to the exits (sinks) such that the total time until all evacuees reach the exits is minimized. The formulation explicitly incorporates the constraints of shared information in providing online instructions to evacuees, ensuring that evacuees departing from an intermediate or source location at a mutual point in time receive common instructions. Arc travel time and capacity, as well as supply at the nodes, are permitted to vary with time and capacity is assumed to be recaptured over time. The BEPSI is shown to be NP‐hard. An exact technique based on Benders decomposition is proposed for its solution. Computational results from numerical experiments on a real‐world network representing a four‐story building are given. Results of experiments employing Benders cuts generated in solving a given problem instance as initial cuts in addressing an updated problem instance are also provided. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

脉冲等离子体推力器羽流的粒子模拟

目前微小卫星正在积极地发展中,脉冲等离子体推力器是其推进系统的一个重要发展方向,为了能够将PPT成功地运用于空间,需对其羽流进行研究.将DSMC(Direct Simulation Monte-Carlo)/PIC(Particle in Cell)流体混合算法与一维MHD放电模型相结合,一体化模拟NASA Glenn PPT羽流,对不同出口偏转角的羽流场进行模拟,并与实验结果进行了比较.计算结果显示引入出口速度的偏转角提高了模型的羽流扩散能力,羽流的扩散角是影响羽流的一个主要因素.