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     

废旧轮胎压缩试验与数值模拟

为更好地将废旧轮胎应用于落石灾害防护领域,对不同型号的废旧轮胎进行了单向重复压缩试验,并对单个轮胎分别进行了2个相互垂直方向上的重复压缩试验,利用LS-DYNA软件模拟了废旧轮胎的压缩试验过程。结果表明:废旧轮胎具有明显的弹性特征和被重复利用的性质,能够重复承受较大变形且割线刚度降低较小;一个方向上被压缩过的废旧轮胎沿圆周方向旋转90°后再进行压缩,其割线刚度几乎能够恢复到初始状态;废旧轮胎的有限元简化模型较为合理,在落石灾害防护领域有着广阔的应用前景。     

一类超混沌系统的全局有限时间同步与全局渐近同步

为了给超混沌系统在保密通信中的应用提供理论支撑,研究了一类含交叉项、立方项和常数项的超混沌系统的全局有限时间同步和全局渐近同步问题.首先,采用广义线性状态误差反馈控制器建立了该类超混沌系统的两个有限时间同步架构,应用有限时间稳定性理论和代数不等式技巧证明了该类超混沌系统的有限时间同步定理;然后,再将该定理应用于超混沌R...     

虚拟战场环境特殊效果仿真

系统研究了基于粒子系统的战场特殊效果建模仿真,统筹兼顾逼真性、实时性和开放性,采用面向对象的方法开发了经过优化的战场特殊效果通用粒子系统模型,并对常见特殊效果进行了具体实现,结果表明该模型具有良好的可重用性、可扩充性和可移植性。     

一个具有相互独立、不同分布服务时间序列的排队模型

讨论的排队模型 ,放宽了GI/G/1系统中“服务时间独立同分布”的限制 ,只要求各服务时间相互独立 ,因而较GI/G/1排队模型能更合理地拟合实际问题 .在此较宽的条件下 ,利用补充变量的方法 ,求得了该排队系统队长的瞬时分布     

基于滤波算法的对比研究

在处理目标跟踪的过程中,为了与实际接近,动态系统的模型选为非线性,而滤波算法采用非线性系统的滤波方法。在介绍了三种非线性滤波算法(EKF、UKF、PF)的原理和实现的同时,说明了各自适用的范围,以便针对不同问题采取比较便捷的算法来有效地实现算法在实际中的应用。EKF适用于线性化过程中系统对高阶项要求较小的情况下,UKF适用在噪声服从高斯分布的情况下,PF则适用与非高斯分布的情况下。此外,通过实例对三种算法分别进行了跟踪仿真实验,表明UKF、PF算法精度要比EKF算法高,UKF、EKF的实时性比PF好,PF的计算量相对较大。     

基于STK的弹箭半实物飞行实时可视化仿真

随着信息化时代的到来,在先前所建立的弹箭半实物飞行实时仿真系统的基础上,研究了弹箭飞行的实时可视化方案。因此,在弹箭半实物飞行的Windows+RTX实时仿真系统下实现与STK软件的RT3模块的实时数据传输与控制,从而实现弹箭飞行的实时可视化。结果表明:基于STK建立的弹箭半实物仿真实时可视化系统,可以在STK窗口看到弹箭飞行姿态和轨迹的变化,通过对姿态和轨迹进行分析,可以得到该可视化系统满足需要的实时性要求。     

智能火力与指挥控制系统的人机功能分配

智能化是现代战斗机火力与指挥控制系统的发展趋势,如何对系统进行合理的人机功能分配是系统设计进程中关键任务之一.为此,提出一种定性与定量分析相结合的人机功能分配方法.对系统面临的作战任务进行分析,并建立系统的各层功能流程图,在此基础上,采用集对分析法对系统各子功能进行了初步的智能程度确定,然后给出系统的结构模型.最后讨论了系统的综合评价指标体系.该人机功能分配方法为智能火力与指挥控制系统的设计提供了一种新的理论参考.     

Terminal allocation problem in a transshipment hub considering bunker consumption

This article investigates the method of allocating arriving vessels to the terminals in transshipment hubs. The terminal allocation decision faced by a shipping alliance has the influence on the scheduled arrival time of vessels and further affects the bunker consumption cost for the vessels. A model is formulated to minimize the bunker consumption cost as well as the transportation cost of inter‐terminal transshipment flows/movements. The capacity limitation of the port resources such as quay cranes (QCs) and berths is taken into account. Besides the terminal allocation, the QC assignment decision is also incorporated in the proposed model. A local branching based method and a particle swarm optimization based method are developed to solve the model in large‐scale problem instances. Numerical experiments are also conducted to validate the effectiveness of the proposed model, which can save around 14% of the cost when compared with the “First Come First Served” decision rule. Moreover, the proposed solution methods not only solve the proposed model within a reasonable computation time, but also obtain near‐optimal results with about 0.1～0.7% relative gap. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 529–548, 2016