On optimality of one‐bug‐look‐ahead policies for a software testing model

The optimality of the One‐Bug‐Look‐Ahead (OLA) software release policy proposed by Morali and Soyer ( 15 ) is re‐examined in this paper. A counterexample is constructed to show that OLA is not optimal in general. The optimal stopping approach is then called upon to prove that OLA possesses weaker sense of optimality under conditional monotonicity and the strong sense of optimality holds under a more restrictive sample‐wise monotonicity condition. The NTDS data are analyzed for illustration, and OLA is shown to be robust with respect to model parameters. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007.     

一种多约束条件下高超声速导弹对地攻击的三维最优变结构制导律

针对高超声速空地导弹多约束高精度末制导的基本需求,在三维解耦的俯仰平面和转弯平面上分别设计制导律。在综合考虑脱靶量、落角、入射角等多种约束条件后,运用最优控制构造的最优制导律设计了一种三维最优变结构制导律,接着利用梯度自适应下降法和T-S模型改进了速度约束控制。最后通过典型弹道的结果显示该制导律能够满足多约束高精度制导的需要,具有良好的弹道性能。     

Optimal burn‐in procedure for periodically inspected systems

Burn‐in is a widely used method to improve the quality of products or systems after they have been produced. In this paper, we study burn‐in procedure for a system that is maintained under periodic inspection and perfect repair policy. Assuming that the underlying lifetime distribution of a system has an initially decreasing and/or eventually increasing failure rate function, we derive upper and lower bounds for the optimal burn‐in time, which maximizes the system availability. Furthermore, adopting an age replacement policy, we derive upper and lower bounds for the optimal age parameter of the replacement policy for each fixed burn‐in time and a uniform upper bound for the optimal burn‐in time given the age replacement policy. These results can be used to reduce the numerical work for determining both optimal burn‐in time and optimal replacement policy. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

电流变流体夹心梁的优化控制

电流变流体的流变性质和力学性质在电场里随电场强度的变化而实时地、可逆地发生变化, 这一特点使得它在自适应结构中的应用受到越来越多的重视。电流变流体夹心梁是在两弹性层间夹入一层电流变材料, 通过控制电流变材料屈服前的流变性质和力学性质来达到控制整个复合梁的动态响应。本文通过建立两端简支的电流变流体夹心梁的结构模型, 模拟分析了复合梁的动态响应及不同激励频率下的优化电场。     

一类折扣型投资模型的最优停止

本文对一类折扣型投资模型进行研究，给出了一个明确的停止规则。     

用非线性规划求解有限推力最优交会

利用非线性规划方法研究了航天器的有限推力最优交会问题。这种方法利用了近年来发展起来的直接优化技术,用分段多项式来表示整个轨道的状态和控制向量,将最优控制问题转化为非线性规划问题。在应用这种方法时,先将整个轨道分为若干推力段和无推力段,然后利用配置方法产生推力段的约束段,利用状态转移矩阵来产生无推力段的约束。最后,对共面轨道情况下的交会进行了数值仿真,验证了方法的有效性和鲁棒性。     

模糊多属性群决策与潜艇作战方案优选

分析了潜艇作战方案的优选实质是一个模糊多属性的群决策过程,建立了模糊多属性群决策的一般模型,介绍了一种以模糊理想解与模糊负理想解同时作为参照基准,以海明距离作为测度工具,以相对贴近度作为衡量标准的模糊折衷型多属性群决策方法,应用实例表明此方法可行有效。     

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     

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。