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     

Bullwhip and reverse bullwhip effects under the rationing game

When an unreliable supplier serves multiple retailers, the retailers may compete with each other by inflating their order quantities in order to obtain their desired allocation from the supplier, a behavior known as the rationing game. We introduce capacity information sharing and a capacity reservation mechanism in the rationing game and show that a Nash equilibrium always exists. Moreover, we provide conditions guaranteeing the existence of the reverse bullwhip effect upstream, a consequence of the disruption caused by the supplier. In contrast, we also provide conditions under which the bullwhip effect does not exist. In addition, we show that a smaller unit reservation payment leads to more bullwhip and reverse bullwhip effects, while a large unit underage cost results in a more severe bullwhip effect. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 203–216, 2017     

舰用蓄电池溶液密度测量装置性能改进的力学原理

旧式舰用蓄电池的内部溶液密度测量传感系统是采用弹簧固定的,装置受船体的加速度的影响很大,常常不能正确地反应蓄电池内硫酸溶液的密度变化而给出信号,误差很大．作者对悬浮式的传感方式作出理论上的论证,并分析了传感器浮出液面的体积为浸入溶液中的体积多少倍的情况下加速度的影响最小．     

利用振动信号诊断发动机气门间隙异常故障

提出了利用气缸盖表面振动信号诊断发动机配气机构气门间隙异常故障的方法,分析了气缸盖表面振动响应与气门机构状态的关系。通过实验和计算,从气缸盖表面的振动信号得到气门间隙异常状态的信息。在此基础上,提出了一种简单有效的时域分析诊断方法。     

A hybrid method for simulation factor screening

Factor screening is performed to eliminate unimportant factors so that the remaining important factors can be more thoroughly studied in later experiments. Controlled sequential bifurcation (CSB) and controlled sequential factorial design (CSFD) are two new screening methods for discrete‐event simulations. Both methods use hypothesis testing procedures to control the Type I Error and power of the screening results. The scenarios for which each method is most efficient are complementary. This study proposes a two‐stage hybrid approach that combines CSFD and an improved CSB called CSB‐X. In Phase 1, a prescreening procedure will estimate each effect and determine whether CSB‐X or CSFD will be used for further screening. In Phase 2, CSB‐X and CSFD are performed separately based on the assignment of Phase 1. The new method usually has the same error control as CSB‐X and CSFD. The efficiency, on the other hand, is usually much better than either component method. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

培养造就高素质新型军事人才的根本指针——学习胡锦涛关于新形势下军队人才建设的重要论述

胡锦涛关于新形势下军队人才建设的重要论述,阐发和回答了新形势下军队人才建设的重大理论问题和实践问题,是我党三代领导核心人才建设思想的继承和发展.其重要论述主要体现在:把加紧培养高素质新型军事人才作为加快转变战斗力生成模式的要素和支撑;以培养"四个方面人才"为重点推进人才战略工程;在提高我军履行使命任务能力的实践中锻造新...     

Contrasting the Impacts of Combat and Humanitarian Assistance/Disaster Relief Missions on the Mental Health of Military Service Members

Abstract

We study the differential impacts of combat and humanitarian assistance/disaster relief (HA/DR) missions on the mental health of U.S. Marine Corps members. The deployment experiences of any individual Marine are plausibly random conditional on the observable characteristics which are used to assign Marines into units. Leveraging this exogenous variation, we compare the incidence of post-traumatic stress disorder (PTSD) and suicide deaths among Marines who deployed to either Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) or HA/DR missions between 2001 and 2011. We find that the hazard of PTSD is close to eight times higher among Marines returning from OEF/OIF compared to those never deployed, and just 1.33 times higher among those returning from HA/DR (and never participated in OEF/OIF). Those returning from OEF/OIF missions are 1.81 times more likely than those never deployed to die by suicide when they were still active duty, and the hazard increases to almost 3 after they have left the military. In contrast, we find no difference in the hazards of suicide death between those that deployed to only HA/DR missions and non-deployed Marines.     

Data-driven research in retail operations—A review

We review the operations research/management science literature on data-driven methods in retail operations. This line of work has grown rapidly in recent years, thanks to the availability of high-quality data, improvements in computing hardware, and parallel developments in machine learning methodologies. We survey state-of-the-art studies in three core aspects of retail operations—assortment optimization, order fulfillment, and inventory management. We then conclude the paper by pointing out some interesting future research possibilities for our community.     

电子信息化武器装备标准化发展趋势

本文从电子信息化武器装备的概念和标准化工作出发,简要分析了以美军为主的外军电子信息化武器装备标准化发展趋势。并结合我国的国情分析了我军电子信息化武器装备的发展趋势与对策。     

Approximation algorithms for general one‐warehouse multi‐retailer systems

Logistical planning problems are complicated in practice because planners have to deal with the challenges of demand planning and supply replenishment, while taking into account the issues of (i) inventory perishability and storage charges, (ii) management of backlog and/or lost sales, and (iii) cost saving opportunities due to economies of scale in order replenishment and transportation. It is therefore not surprising that many logistical planning problems are computationally difficult, and finding a good solution to these problems necessitates the development of many ad hoc algorithmic procedures to address various features of the planning problems. In this article, we identify simple conditions and structural properties associated with these logistical planning problems in which the warehouse is managed as a cross‐docking facility. Despite the nonlinear cost structures in the problems, we show that a solution that is within ε‐optimality can be obtained by solving a related piece‐wise linear concave cost multi‐commodity network flow problem. An immediate consequence of this result is that certain classes of logistical planning problems can be approximated by a factor of (1 + ε) in polynomial time. This significantly improves upon the results found in literature for these classes of problems. We also show that the piece‐wise linear concave cost network flow problem can be approximated to within a logarithmic factor via a large scale linear programming relaxation. We use polymatroidal constraints to capture the piece‐wise concavity feature of the cost functions. This gives rise to a unified and generic LP‐based approach for a large class of complicated logistical planning problems. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009