城市区域消防安全评估方法研究

城市区域消防安全评估是科学有效地进行城市消防规划、部署和消防法规的制定的重要依据 ,对于城市建设和社会经济的协调发展具有保证和促进作用。根据《中华人民共和国消防法》及《机关、团体、企业、事业单位消防安全管理规定》(6 1号令 )对消防管理对象的界定标准 ,提出两种不同的分类方法 ,确定了城市区域消防安全体系的组成要素 ,采用层次分析法确定了各要素的权重 ,应用多层次多目标系统模糊优选理论 ,建立了城市区域消防安全评价模型 ,对城市区域消防安全评估进行了方法研究和具体计算 ,并应用所设计的模型对北京市宣武区的区域消防安全状况进行了两种方法的分析评估。计算结果证明了方法的有效性 ,用两种不同的分类方法所做出的结果 ,显示了不同分类的一致性。     

浅谈培养解题能力

从深刻理解数学概念内涵、熟悉数学公式及变式和注重解题过程分析三个方面谈如何有效培养学生的解题能力 ,进而促进学生数学能力的发展     

基于马尔柯夫过程的武器系统目标分配问题决策分析

将防空作战中武器系统目标分配决策作为一个在动态随机系统中实现最优化的问题,并用马尔柯夫过程理论进行建模分析,提出新的算法并运用Matlab编程;通过对实行不同策略时武器系统长期平均效能的分析比较,指出在目标分配问题上仅靠原有的静态线性规划决策方法是不够的,还必须考虑动态随机对抗过程本身的特性.     

二阶矩模糊随机过程的均方极限

给出了二阶矩模糊随机过程均方极限的两种定义,证明了这两种定义的等价性,并讨论了二阶矩模糊随机过程均方极限的性质。     

基于Web技术的固定资产管理系统的设计与实现

“基于Web技术管理信息系统”是将Web技术与数据库技术相结合,从而实现动态信息管理的系统。提出了“基于Web技术的固定资产管理系统”的解换方案,进行了系统分析,详述了系统的功能,并对关键技术的实现方法进行了论述。该系统对于提高固定资产管理正规化、现代化、科学化的管理水平有着重要意义。     

液体火箭发动机非线性燃烧不稳定过程的并行仿真

采用计算燃烧学方法对火箭发动机非线性燃烧不稳定工作过程进行了并行数值模拟。气相控制方程组用欧拉坐标系下的Navier Stokes方程组描述 ,液相控制方程组在Lagrangian坐标系下进行描述。气、液两相作用通过方程组的源项互相耦合。编制了串行和并行程序 ,并在并行计算环境下进行了测试。从计算结果可以看出并行计算的效率较高。     

Designing a screening experiment for highly reliable products

Within a reasonable life‐testing time, how to improve the reliability of highly reliable products is one of the great challenges to today's manufacturers. By using a resolution III experiment together with degradation test, Tseng, Hamada, and Chiao (1995) presented an interesting case study of improving the reliability of fluorescent lamps. However, in conducting such an experiment, they did not address the problem of how to choose the optimal settings of variables, such as sample size, inspection frequency, and termination time for each run, which are influential to the correct identification of significant factors and the experimental cost. Assuming that the product's degradation paths satisfy Wiener processes, this paper proposes a systematic approach to the aforementioned problem. First, an intuitively appealing identification rule is proposed. Next, under the constraints of a minimum probability of correct decision and a maximum probability of incorrect decision of the proposed identification rule, the optimum test plan (including the determinations of inspection frequency, sample size, and termination time for each run) can be obtained by minimizing the total experimental cost. An example is provided to illustrate the proposed method. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 514–526, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10024     

On the availability of R out of N repairable systems

An R out of N repairable system consisting of N components and operates if at least R components are functioning. Repairable means that failed components are repaired, and upon repair completion they are as good as new. We derive formulas for the expected up‐time, expected down‐time, and the availability of the system, using Markov renewal processes. We assume that either the repair times of the components are generally distributed and the components' lifetimes are exponential or vice versa. The analysis is done for systems with either cold or warm stand‐by. Numerical examples are given for several life time and repair time distributions. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 483–498, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10025     

Two‐stage component test plans for testing the reliability of a series system

A system reliability is often evaluated by individual tests of components that constitute the system. These component test plans have advantages over complete system based tests in terms of time and cost. In this paper, we consider the series system with n components, where the lifetime of the i‐th component follows exponential distribution with parameter λ_i. Assuming test costs for the components are different, we develop an efficient algorithm to design a two‐stage component test plan that satisfies the usual probability requirements on the system reliability and in addition minimizes the maximum expected cost. For the case of prior information in the form of upper bounds on λ_i's, we use the genetic algorithm to solve the associated optimization problems which are otherwise difficult to solve using mathematical programming techniques. The two‐stage component test plans are cost effective compared to single‐stage plans developed by Rajgopal and Mazumdar. We demonstrate through several numerical examples that our approach has the potential to reduce the overall testing costs significantly. © 2002 John Wiley & Sons, Inc. Naval Research Logistics, 49: 95–116, 2002; DOI 10.1002/nav.1051     

分块模幂算法

RSA是目前最成熟的一种公钥密码体系 ,RSA加解密算法的速度依赖于模幂算法 ,因而快速模幂算法一直是人们感兴趣的课题。该文提出了一种基于分块的模幂算法 ,对算法复杂性进行了讨论 ,并与其他模幂算法作了比较 ,从理论上论证了它具有更快的模幂速度