Robust shortest path problems with two uncertain multiplicative cost coefficients

We consider a robust shortest path problem when the cost coefficient is the product of two uncertain factors. We first show that the robust problem can be solved in polynomial time by a dual‐variable enumeration with shortest path problems as subproblems. We also propose a path enumeration approach using a K ‐shortest paths finding algorithm that may be efficient in many real cases. An application in hazardous materials transportation is discussed, and the solution methods are illustrated by numerical examples. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

基于拉盖尔模型的超声信号渡越时间测量性能分析

传统窄带模型仅能通过数值计算统计出超声信号渡越时间的测量性能。针对这一问题,提出基于拉盖尔模型计算理论克拉下限的方法。研究了拉盖尔函数及其时间导数的性质,得到时间导数内积矩阵,并将其应用到费舍尔矩阵中,能够快速精确计算克拉下限。对混合指数模型仿真表明,在高斯白噪声背景下,渡越时间方差与理论克拉下限具有良好的一致性;受窄带噪声和反射等因素影响,实测数据的渡越时间方差与理论克拉下限存在较大偏差。     

Switching costs,dynamic uncertainty,and buyer–seller relationships

We analyze strategic relationships between buyers and sellers in markets with switching costs and dynamic uncertainty by investigating the scenario wherein a representative buyer trades with two foreign sellers located in the same foreign country. We show that, under exchange rate uncertainty, switching costs may lead to switching equilibria where both sellers co‐exist in the market with the buyer, or no‐switching equilibria where either seller captures the market. The presence of exchange rate uncertainty facilitates competition by allowing the sellers to co‐exist in the market with the buyer. However, if the level of uncertainty is beyond a threshold, the only viable equilibria are those where one of the sellers captures the market. Further, depending on the level of exchange rate uncertainty and the sellers' variable costs, switching costs may either raise or lower the level of prices in long‐term contracts between the buyer and the sellers. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

舰船辐射噪声对声纳作用距离影响的不确定性研究

为了研究目标舰船辐射噪声对声纳作用距离产生的影响,用蒙特卡洛方法对目标航速进行模拟。通过经验公式得出舰船的辐射噪声级并进行统计分析,得出舰船辐射噪声的概率分布直方图,由此可以导出被动声纳作用距离的概率分布直方图。相对于传统的声纳作用距离预报结果,该方法给出的作用距离预报结果是一个满足某一分布的随机变量,而非一个确定的值,为作用距离的预报提供了概率的依据,为艇指挥员的决策提供了定量信息。同时,通过计算得出舰船航速的均方差与声纳作用距离的均方差基本成线性递增关系。     

The impact of demand uncertainty on product line design under endogenous substitution

The existing product line design literature devotes little attention to the effect of demand uncertainty. Due to demand uncertainty, the supply‐demand mismatch is inevitable which leads to different degrees of lost sales depending on the configuration of product lines. In this article, we adopt a stylized two‐segment setup with uncertain market sizes and illustrate the interplay between two effects: risk pooling that mitigates the impact of demand uncertainty and market segmentation that facilitates consumer differentiation. Compared to downward substitution, inducing bidirectional substitution through product line decisions including quality levels and prices can yield greater risk pooling effects. However, we show that the additional benefit from the risk pooling effect cannot compensate for the reduced market segmentation effect. We demonstrate that the presence of demand uncertainty can reduce the benefit of market segmentation and therefore the length of product lines in terms of the difference between products. We also propose three heuristics that separate product line and production decisions; each of these heuristics corresponds to one particular form of demand substitution. Our numerical studies indicate that the best of the three heuristics yields performance that is close to optimality. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 143–157, 2015     

Technical note – operational statistics: Properties and the risk‐averse case

Consider a repeated newsvendor problem for managing the inventory of perishable products. When the parameter of the demand distribution is unknown, it has been shown that the traditional separated estimation and optimization (SEO) approach could lead to suboptimality. To address this issue, an integrated approach called operational statistics (OS) was developed by Chu et al., Oper Res Lett 36 (2008) 110–116. In this note, we first study the properties of this approach and compare its performance with that of the traditional SEO approach. It is shown that OS is consistent and superior to SEO. The benefit of using OS is larger when the demand variability is higher. We then generalize OS to the risk‐averse case under the conditional value‐at‐risk (CVaR) criterion. To model risk from both demand sampling and future demand uncertainty, we introduce a new criterion, called the total CVaR, and find the optimal OS under this new criterion. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 206–214, 2015     

三维模型大尺度坐标测量辅助设计与评估方法

针对大尺度产品三维模型坐标测量信息缺乏和面向任务坐标测量结果质量评价困难的问题,引入新一代产品几何量技术规范(GPS),提出了基于CATIA二次开发技术的坐标测量辅助设计方法,设计了CAD与CMM集成的XML数据结构,建立了坐标测量数据的UML模型;实现了符合新一代GPS要求的测量方案脚本化描述,开发了部分数据处理算法;提出了基于Monte Carlo方法的坐标测量不确定度评估方案和流程。基于以上技术开发了基于三维模型的大尺度坐标测量设计与评估系统并应用于飞机装配中的部件位姿测量,结果表明,设计的测量方案能够满足飞机柔性装配对接的要求,验证了上述方法的有效性。     

军事通信领域上下文本体建模及不确定性推理＊

为支持军事通信业务的智能化,研究了军事通信业务上下文信息的表示和推理,提出了一种表示业务上下文信息的语法结构、语义以及上下文元信息的本体建模方法。并利用贝叶斯网络理论,提出了一种支持不确定性推理的业务上下文认知模型的构建方法,最后通过案例分析验证了模型和结论的合理性。     

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。     

Banach空间中严格拟伪压缩映像族公共不动点的迭代算法

根据Banach空间中严格拟伪压缩映像不动点的迭代格式,将其扩充到无穷多个严格拟伪压缩映像族公共不动点的迭代算法,证明其强收敛定理,扩展了已知的相关结果．