二阶中立型含逐段常滞量微分方程的伪概周期解的存在性

讨论下列中立型含逐段常滞量微分方程的伪概周期解d2dt2(x(t)+p(t)x(t-1))=qx(2[t+12])+g(t,x(t),x[t])采用不动点定理和构造伪概周期序列的方法,得到了此方程的伪概周期解的存在性,并推广了文献[5～8]中的有关结果。     

无源时差定位系统的模糊无解问题

本文对平面三站无源时差定位系统的定位过程中可能出现的无解和模糊现象进行了探讨,找出了无解分布与布站以及观测噪声方差大小之间的规律,得出了模糊分布与布站之间的关系,并提供了一些解决方法。     

运动激光辐照圆柱薄壳温度场的数值模拟

对圆柱薄壳在四种不同运动模式激光源辐照下的温度场分布进行了分析研究。运用傅立叶级数展开法推导了在不同运动模式激光源作用下圆柱薄壳温度场的解析表达式,并对该解析表达式进行了编程计算,其计算结果与有限元解吻合良好。详细分析了旋转角速度与平动速度对圆柱壳温升分布的影响,发现在往复运动加热模式下光斑区域的温升变化最为剧烈。计算结果为导弹的抗激光辐射提供了理论依据。     

武警部队快速机动中最优路径的实现

紧急条件下武警部队快速机动最优路径，是一个多目标多约束随机动态交通网络寻优问题。在分析交通网络拓扑化特点及最短路模型前提下，着重研究道路通行能力带给复杂公路网络道路寻优问题的影响，并结合GIS系统利用改进的Dijkstra算法求解。     

临近空间拦截弹最优弹道跟踪制导律

针对拦截临近空间高超声速飞行器的弹道跟踪过程,基于线性二次型调节器理论和高斯伪谱法设计一种跟踪制导律。为了对标称弹道进行精确跟踪,考虑线性二次型跟踪问题,应用最优控制理论推导最优解的充要条件,得到带时变增益的线性状态反馈控制量的表达式;基于高斯伪谱法,在离散的勒让德-高斯点上利用标称弹道数据计算差分矩阵和系数矩阵,求得状态扰动反馈控制律。仿真结果表明,与基于求解矩阵黎卡提方程的方法相比,该方法选取较少的节点即可获得高精度的反馈控制量,且运算效率大幅提高,满足在线实施要求。     

引入区域量化的相控阵天线维修优化模型

针对大型相控阵天线维修成本高、多部件维修时机难以确定、模型仿真计算困难等问题,提出一种引入区域量化的维修优化模型。建立天线阵列的区域量化模型,将天线阵列维修问题转化成一个由不同区域阵元组成的k/n系统维修优化问题。以使用可用度为约束条件,以单位时间维修费用最小为优化目标,建立引入区域量化的大型相控阵天线多部件视情维修决策优化模型,并通过算例仿真与分析进行了模型验证。结果表明:提出的维修优化模型真实有效,能够很好地解决分布不均匀的相控阵天线维修优化问题。     

基于改进快速扩展随机树的机械臂路径规划

针对机械臂路径规划问题,提出一种基于改进RRT算法的路径规划方法。改进RRT结合了目标偏置策略和贪婪生长策略的优点,在随机采样时,以一定概率使采样点偏置为目标节点,降低随机采样的盲目性,在目标节点方向上采用贪婪式扩展策略,增加随机树局部方向上的生长速度。RRT法规划路径结果并非最优,提出改进GPP法删除多余路径节点,优化机械臂运动路径。通过与Biased-RRT和Greedy-RRT数值仿真结果对比,证明了改进RRT在计算时间、迭代次数、扩展节点数上均优于以上方法。在机械臂两种典型工作环境中的仿真结果表明,使用该方法可以较好解决排爆机械臂避障路径规划问题。     

Analysis and optimal design of discrete order picking technologies along a line

Order picking accounts for most of the operating expense of a typical distribution center, and thus is often considered the most critical function of a supply chain. In discrete order picking a single worker walks to pick all the items necessary to fulfill a single customer order. Discrete order picking is common not only because of its simplicity and reliability, but also because of its ability to pick orders quickly upon receipt, and thus is commonly used by e‐commerce operations. There are two primary ways to reduce the cost (walking distance required) of the order picking system. First is through the use of technology—conveyor systems and/or the ability to transmit order information to pickers via mobile units. Second is through the design—where best to locate depots (where workers receive pick lists and deposit completed orders) and how best to lay out the product. We build a stochastic model to compare three configurations of different technology requirements: single‐depot, dual‐depot, and no‐depot. For each configuration we explore the optimal design. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

软件无失效测试数据的统计分析

软件可靠性估计是软件可靠性研究的重要问题之一,文中对分布式软件系统可靠性的评估方法进行了研究,给出了软件系统可靠度的最优置信下限.最后以某大型软件的评估为例,说明该方法的应用.     

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