Integrated production scheduling and preventive maintenance planning for a single machine under a cumulative damage failure process

This paper finds the optimal integrated production schedule and preventive maintenance plan for a single machine exposed under a cumulative damage process, and investigates how the optimal preventive maintenance plan interacts with the optimal production schedule. The goal is to minimize the total tardiness. The optimal policy possesses the following properties: Under arbitrary maintenance plan when jobs have common processing time, and different due dates, the optimal production schedule is to order the jobs by earliest due date first rule; and when jobs have common due date and different processing times, the optimal production schedule is shortest processing time first. The optimal maintenance plan is of control limit type under any arbitrary production schedule when machine is exposed under a cumulative damage failure process. Numerical studies on the optimal maintenance control limit of the maintenance plan indicate that as the number of jobs to be scheduled increases, the effect of jobs due dates on the optimal maintenance control limit diminishes. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

基于XML／RDF的油料装备模块化协同设计网格主体资源表达

针对协同设计网格中油料装备模块化协同设计主体资源规范化表达问题,提出按照模块设计能力划分油料装备模块化协同设计主体资源的分类体系,给出油料装备模块化协同设计主体资源的信息描述模型。在此基础上,采用元数据完成了油料装备模块化协同设计主体资源描述的元数据集的定义,并采用可扩展的资源描述框架RDF实现了元数据集的描述,规范了具有值域要求属性的赋值空间,给出了基于元数据集的油料装备模块化协同设计主体资源的RDF描述方法,解决了协同设计网格中统一完整和无二义性地描述资源对象的问题,并提出了利用资源表达向导的策略,规范和简化了资源主体的资源表达。     

Predictability of operational processes over finite horizon

Operational processes are usually studied in terms of stochastic processes. The main information measure used for predictability of stochastic processes is the entropy rate, which is asymptotic conditional entropy, thus not suitable for application over a finite horizon. We use the conditional entropy to study the predictability of stochastic processes over the finite horizon. It is well‐known that the conditional entropies of stationary processes decrease as the processes evolve, implying that, on average, their pasts become more informative about prediction of their future outcomes. Some important operational processes such as martingale, models for maintenance policies, nonhomogeneous Poisson, and mixed Poisson processes are nonstationary. We show that as a nonstationary process evolves, it may provide more information or less information about the future state of the system. We develop results for comparing the predictability of stochastic processes. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

面向任务的战术行动自主协同关系模型

在信息化战争的大背景下,战术行动中团队协同作战一直是研究的重点问题,而如何建立自主协同关系是团队协同研究的一个难点问题。在分析已有团队协同理论和框架的基础上,提出一种面向任务的战术行动自主协同关系模型建立方法。该模型首先根据当前战场态势和上级任务发布自主协同任务集合,各作战单元根据战场态势和自主决策自愿参与自主协同任务,其次利用作战单元与自主协同任务间的相互关系实现对关键角色的判断。如果关键协同成员参与自主协同任务则自主协同关系建立成功,反之,建立失败。     

Dynamic service rate control for a single‐server queue with Markov‐modulated arrivals

We consider the problem of service rate control of a single‐server queueing system with a finite‐state Markov‐modulated Poisson arrival process. We show that the optimal service rate is nondecreasing in the number of customers in the system; higher congestion levels warrant higher service rates. On the contrary, however, we show that the optimal service rate is not necessarily monotone in the current arrival rate. If the modulating process satisfies a stochastic monotonicity property, the monotonicity is recovered. We examine several heuristics and show where heuristics are reasonable substitutes for the optimal control. None of the heuristics perform well in all the regimes and the fluctuation rate of the modulating process plays an important role in deciding the right heuristic. Second, we discuss when the Markov‐modulated Poisson process with service rate control can act as a heuristic itself to approximate the control of a system with a periodic nonhomogeneous Poisson arrival process. Not only is the current model of interest in the control of Internet or mobile networks with bursty traffic, but it is also useful in providing a tractable alternative for the control of service centers with nonstationary arrival rates. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 661–677, 2013     

存储体编译和布局协同的片上缓存设计方法

为了提高片上缓存的速度、降低面积和功耗,提出了一种存储体编译和布局协同的片上缓存设计方法。该方法基于存储体在芯片上的不同空间位置预估该存储体的时序余量,分别采用拆分/合并、尺寸调整、阈值替换和长宽比变形等多种配置参数穷举组合进行存储体编译,根据时序余量选择最优的静态随机存取存储器存储体编译配置。将该方法与现有的物理设计步骤集成为一个完整的设计流程。实验结果表明,该方法能够降低约9.9%的功耗,同时缩短7.5%的关键路径延时。     

Coating processes towards selective laser sintering of energetic material composites

This research aims to contribute to the safe methodology for additive manufacturing (AM) of energetic materials. Coating formulation processes were investigated and evaluated to find a suitable method that may enable selective laser sintering (SLS) as the safe method for fabrication of high explosive (HE) compositions. For safety and convenience reasons, the concept demonstration was conducted using inert explosive simulants with properties quasi-similar to the real HE. Coating processes for simulant RDX-based microparticles by means of PCL and 3,4,5-trimethoxybenzaldehyde (as TNT simulant) are reported. These processes were evaluated for uniformity of coating the HE inert simulant particles with binder materials to facilitate the SLS as the adequate binding and fabrication method. Suspension system and single emulsion methods gave required particle near spherical morphology, size and uniform coating. The suspension process appears to be suitable for the SLS of HE mocks and potential formulation methods for active HE composites. The density is estimated to be comparable with the current HE compositions and plastic bonded explosives (PBXs) such as C4 and PE4, produced from traditional methods. The formulation method developed and understanding of the science behind the processes paves the way toward safe SLS of the active HE compositions and may open avenues for further research and development of munitions of the future.     

地心甚高轨道星座构形协同捕获控制策略

针对地心甚高轨道星座构形协同捕获控制问题,基于虚拟编队方法设计了协同捕获控制策略,采用三脉冲燃耗最优轨迹规划算法对构形捕获轨迹进行协同规划;并且结合自适应全程积分滑模控制器对卫星各自转移轨迹进行跟踪控制。以10万km轨道高度的三星星座构形捕获为例进行仿真验证,仿真结果表明:该策略可以有效应用于地心甚高轨道星座构形捕获控制,能够在燃耗较少的情况下使星座中卫星同时到达各自的标称位置,同时具有较高的精度。     

基于VR的虚拟火炮行为仿真

针对虚拟武器装备行为仿真过程中存在的运动仿真复杂、多部件协调操作仿真困难等问题,本文基于虚拟现实建模工具构建了某型传统火炮的三维模型-虚拟火炮,为行军行为仿真过程中运动轨迹选取、运动姿态控制、碰撞检测及响应等问题提供了合理的解决方法;在用炮和收炮行为仿真过程中,重点设计了时间驱动算法来解决多部件之间的协调操作仿真问题。通过对虚拟火炮的特定行为进行可视化仿真,验证了文中行为仿真研究方案的合理性及算法设计的正确性。     

不确定条件下编队协同作战空中目标威胁评估

针对决策环境的不确定性,对不确定条件下舰艇编队协同作战的空中目标威胁评估过程进行了深入研究;在此基础上,根据舰艇编队协同决策的特点,综合运用风险型多属性决策理论,建立了满足不同决策层的舰艇目标威胁评估模型和编队目标威胁评估模型,从而提出了不确定条件下编队协同作战的空中目标威胁评估方法。最后,通过实例说明了所提方法的有效性。