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。     

地球静止轨道高能电子通量在线预测模型研究

利用粒子群优化算法和最小二乘支持向量机，建立了地球静止轨道高能电子通量(1.8-3.5MeV)在线预测模型。针对粒子群优化算法，提出了一种新的粒子群多样性测度计算方法，有效改善了其早熟收敛现象；基于改进的粒子群优化算法优化最小二乘支持向量机的正则化参数和核参数；利用滑动时间窗口策略更新模型数据，设计变量选择触发机制以及模型的再学习机制实现模型的在线预测功能。[根据题目的调整，对摘要做了相应改动]通过对2000年电子通量监测数据和相关太阳风、地磁参数等实际数据进行提前1-3天的预测实验，表明了所建在线预测模型具有较高的预测性能，有一定的实用价值。     

一种空中目标的不确定性威胁程度预测模型

目标威胁预测是对空态势和威胁估计的重要内容.针对空中目标飞行控制的基本特点,建立了基于经验公式的空中目标不确定性位置预测模型,进一步推导了不确定性威胁概率预测的模型和实用算法.仿真结果证明了模型的有效性,可用于多类空中目标意图推理及威胁判断.     

Scheduling parallel machines with inclusive processing set restrictions

We consider the problem of assigning a set of jobs to different parallel machines of the same processing speed, where each job is compatible to only a subset of those machines. The machines can be linearly ordered such that a higher‐indexed machine can process all those jobs that a lower‐indexed machine can process. The objective is to minimize the makespan of the schedule. This problem is motivated by industrial applications such as cargo handling by cranes with nonidentical weight capacities, computer processor scheduling with memory constraints, and grades of service provision by parallel servers. We develop an efficient algorithm for this problem with a worst‐case performance ratio of + ε, where ε is a positive constant which may be set arbitrarily close to zero. We also present a polynomial time approximation scheme for this problem, which answers an open question in the literature. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

不确定情况下协同空战目标分配方法

现代空战环境下出现的大量不确定信息, 现在常用的协同目标分配模型都没有考虑到这种情况.针对这种情况,将随机规划引入到协同空战目标分配研究中,在一般期望值模型的基础上,建立了多机空战协同目标分配期望值模型,并利用随机模拟、神经网络和遗传算法结合而成的混合智能算法来求解该期望值模型.2∶4协同空战仿真结果表明该模型的有效性.     

基于支持向量机的战套器材组配决策研究

通过交叉验证找出影响战套组配的3个重要参数的取值,并构建飞机的战套器材组配决策模型,最后利用libsvm工具包对某型军用飞机的战套组配的可行性进行了分析。结果表明：基于支持向量机的战套器材组配决策是可行的。