PREVENTIVE ATTACKS AGAINST NUCLEAR PROGRAMS AND THE “SUCCESS” AT OSIRAQ

Advocates of the preventive use of force against emerging nuclear, biological, or chemical programs often look to the allegedly successful 1981 Israeli airstrike against Iraqi nuclear facilities at Osiraq. According to the conventional wisdom, this attack may have prevented Iraq from going nuclear before Operation Desert Storm in 1991. This article assesses the claim that the 1981 attack substantially delayed Iraqi acquisition of nuclear weapons, both by revisiting older debates and by introducing new evidence from Iraqi scientists. The article casts doubt on the conclusion that the attack was successful for three reasons: (1) the reactor itself was not well equipped to generate plutonium for a nuclear weapon; (2) illegal plutonium production would likely have caused a cutoff in the supply of nuclear fuel and an end to weapons activities; and (3) the attack may have actually increased Saddam's commitment to acquiring weapons. These conclusions have implications for the Bush Doctrine, as the lack of success in 1981 casts doubt on the possible success of future attacks against nuclear programs.     

分级教学中A班学生英语听力问题及对策研究

听力理解在英语教学中的重要性已经受到教育工作者的普遍重视,但对于分级教学中出现的听力理解问题及对策少有研究。两年来,通过对武警学院英语分级教学情况的跟踪调查,研究探讨A班学生在听力学习方面的问题,并提出相应的解决方法,从而为今后的分级教学总结经验。     

一种改进的变异粒子群算法研究

粒子群优化算法PSO(Partic le Swarm Optim ization)是一类性能优越的寻优算法。但由于早熟问题,影响了算法性能的发挥。针对这一问题,引入粒子距离的概念,提出一种新的PSO改进方法(称为NA-PSO)。通过求解组网雷达的系统偏差,表明了NA-PSO算法的可行性,与对比方法相比较,能有效配准,且具有更好的收敛精度和更快的进化速度。     

齿轮箱故障诊断特征级数据关联方法研究

提出了齿轮箱故障诊断特征级数据关联的定义．在该定义的基础上,提出了基于Bootstrap方法的小样本诊断特征参数关联的方法．利用某型齿轮箱振动试验台测取的振动加速度响应信号对提取的特征参数进行了关联评估,基于Bootstrap方法的特征级数据关联方法正确区分出了效果不好的特征参数,证实了该数据关联方法的正确性．     

A metaheuristic scheduling procedure for resource-constrained projects with cash flows

Resource-constrained project scheduling problems with cash flows (RCPSPCF) are complex, combinatorial optimization problems. Many heuristics have been reported in the literature that produce reasonable schedules in limited project environments. However, the lack of a heuristic that dominates under differing project conditions can lead to a suboptimal choice of an appropriate heuristic for scheduling any given project. This may result in poor schedules and monetary losses. This paper reports on the application of the tabu search metaheuristic procedure for the RCPSPCF. Strategies for neighborhood generation and candidate selection that exploit the special features of the problem are combined with a simple multiheuristic start procedure. Extensive experimentation, with multiple data sets and comparison with an upper bound, indicates a significant improvement, both in project Net Present Value (NPV) as well as the number of projects, where the metaheuristic outperforms the best known heuristics in the literature. More specifically, this procedure produces the best schedules in over 85% of the projects tested, in contrast to the best single-pass heuristics which have been shown to dominate in at most 20% of the same cases. This iterative, general purpose heuristic is able to adapt significantly better to the complex interactions of the many critical parameters of the RCPSPCF than single-pass heuristics that use more specific information about each project environment. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 912–927, 1999     

Primal dual algorithms for the vehicle refueling problem

Mehrez, Stern, and Ronen have defined a vehicle refueling problem in which a fleet of vehicles travels on a round-trip, self-contained mission from a common origin, with the objective of maximizing the operational range of the fleet. They have defined a “pure refueling chain” strategy for transferring fuel between vehicles in the fleet, and have solved the problem in the special cases when all vehicles have the same fuel capacity or consumption rate. In this article we present algorithms for the general case, where vehicles have different capacities and consumption rates. Our approach is based on a new primal dual formulation of the problem. The exact algorithm was effective to find the optimal solution for a fleet size n ⩽13. For larger fleets, we present an approximation version of it, which very quickly found a solution within 1% of the maximum possible range for arbitrarily large (up to n = 200) fleets. We also show that a small number of the best vehicles can always reach almost the same range as a large fleet. © 1992 John Wiley & Sons, Inc.     

Parametric studies in transportation-type problems

In this paper we present some results in parametric studies on several transportation-type problems. Specifically, a characterization is obtained for the optimal values of the variables in the problem of determining an optimal growth path in a logistics system. We also derive an upper bound beyond which the optimal growth path remains the same. The results are then extended to the goal programming model and the prespecified market growth rate problem.     

一种基于交叉关联积分的功放无意调制识别方法

针对同频率连续波信号中的功放指纹分析问题,提出一种基于相空间交叉关联积分的无意调制识别方法(CCI-UMI).该方法通过对功放无意调制的机理分析和对重构矢量沿轨迹概率(PDT)的理论分析,建立了相轨迹比较的基本理论依据和参数选择方法.采用多尺度交叉关联积分算法,在重构相空间实现了对信号细微差别的灵敏比较.对任意波发生器两路通道实测数据的分类实验表明:本方法识别率较高,经合理选择参数,在低信噪比下可获得比功率谱方法和相空间微分方法更好的分类性能.     

生态课堂的内涵、价值与生成

课堂是育人的主渠道,课堂变革的本质就是回归生命,构建生态课堂是教育发展的必然.生态课堂的构成要素包括教师、学生、教学内容、教学环境,这四个要素彼此关联、相互作用.生态课堂的价值理念就是尊重生命的自主发展、提倡师生的合作共生、注重课堂的多维互动与动态生成.构建生态课堂,需要树立生态的课堂意识、让课堂回归生活世界、引导学生进行自主探究、塑造新型的师生关系、建立多元开放的评价制度.