A supply chain design model with unreliable supply

Uncertainties abound within a supply chain and have big impacts on its performance. We propose an integrated model for a three‐tiered supply chain network with one supplier, one or more facilities and retailers. This model takes into consideration the unreliable aspects of a supply chain. The properties of the optimal solution to the model are analyzed to reveal the impacts of supply uncertainty on supply chain design decisions. We also propose a general solution algorithm for this model. Computational experience is presented and discussed. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

The strategic effects of a merger upon supplier interactions

We consider how a merger between two naturally differentiated dealers affects their interactions with a common supplier and identify conditions under which the merger can increase or decrease the combined net worth of the two firms. Among other things, we find that the attractiveness of merging depends upon the extent to which end demand can be stimulated by either an upstream supplier or the dealers. Specifically, the greater the supplier's ability to invest in stimulating end demand, the more likely it is that the naturally differentiated firms will be better off operating independently than merging. On the other hand, if the greatest opportunities for stimulating demand are through the service that is provided by the dealers, then merging their operations will be more attractive. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

Designing safety space in a supply chain to handle system‐wide disruptions

In some supply chains serious disruptions are system wide. This happens during periods of severe weather, as when storms cause shuttle tankers serving oil platforms in the North Sea to stop movements of crude oil, barges are frozen in the Mississippi, or all airplanes are grounded after a blizzard. Other notable instances of system‐wide disruption happened after the attack on the World Trade Center when all aircraft were grounded and the natural gas and crude‐oil pipelines were tangled by hurricanes in 2005. We model a situation where shutting down supply facilities is very difficult and expensive because of excessive inventory buildup from an inability to move out the production. We present a planning model that balances the cost of spare capacity versus shutting down production when planning for disruptions. The model uses an assignment model embedded in a simulation. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

基于概率风险的系统安全性分析

为得到系统层次上的安全性概率风险,获得定量的安全性决策依据,设计了基于概率风险的系统安全性分析方法,该方法将系统按某种标准划分成相应子系统,统计得到各子系统所有的危险源,建立相应的因果链,通过一定法则得到基于系统层次的概率风险,同时还讨论了设计方法中概率风险计算的难点问题。     

非圆链轮分度线的样条拟合

非圆链传动中，两链轮分度线为非圆形，该曲线数学表达式是一个非线性函数方程组，严格求解这一函数方程组似乎毫无希望，但是依据动力学的方法可以构造此曲线的切线系，即一切线多边形。从而将这一问题转化为求与切线多边形每条边相切的逼近曲线。     

马尔可夫链最优停止的值函数

本文讨论了时间无限的马尔可夫链的最优停止问题。对于无限状态情况,给出了其最优停止变量以及值函数存在的一个充分条件;对于有限状态情况,这个充分条件以及问题的计算等价于解一个线性规划问题。     

有限马氏链最优停止的线性规划解

离散时间的有限状态马尔可夫链最优停止的值函数存在的一个充分条件是所对应的线性规划有解,且其最优解等于值函数,本文证明这个条件还是必要的。     

Allocation with demand competition: Uniform,proportional, and lexicographic mechanisms

We examine capacity allocation mechanisms in a supply chain comprising a monopolistic supplier and two competing retailers with asymmetric market powers. The supplier allocates limited capacity to retailers according to uniform, proportional, or lexicographic mechanism. We study the impact of these allocation mechanisms on supplier pricing decisions and retailer ordering behavior. With individual order size no greater than supplier capacity, we show that all three mechanisms guarantee equilibrium ordering. We provide precise structures of retailer ordering decisions in Nash and dominant equilibria. Further, we compare the mechanisms from the perspective of the supplier, the retailers, and the supply chain. We show that regardless of whether retailer market powers are symmetric, lexicographic allocation with any priority sequence of retailers is better than the other two mechanisms for the supplier. Further, under lexicographic allocation, the supplier gains more profit by granting higher priority to the retailer with greater market power. We also extend our study to the case with multiple retailers. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 85–107, 2017     

The nexus between military expenditures and economic growth in the BRICS and the US: an empirical note

This empirical note re-examines the causal linkages between military expenditures and economic growth for the BRICS countries (Brazil, Russia, India, China, and South Africa) and that for the USA during the period 1988–2012. Results of Granger causality tests show that military expenditures influence economic growth in the USA, economic growth influences military expenditures in both Brazil and India, a feedback between military expenditures and economic growth in Russia, and no causal relation exists between military expenditures and economic growth in China and South Africa. The findings of this study can provide important policy implications for the BRICS countries and also for the USA.     

Modeling and analysis of vessel casualties resulting from tanker traffic through narrow waterways

In this paper, we present a physics-based stochastic model to investigate vessel casualties resulting from tanker traffic through a narrow waterway. A state-space model is developed to represent the waterway and the location of vessels at a given time. We first determine the distribution of surface current at a given location of the waterway depending on channel geometry, bottom topography, boundary conditions, and the distribution of wind. Then we determine the distribution of the angular drift for a given vessel travelling at a given location of a waterway. Finally, we incorporate the drift probabilities and random arrival of vessels into a Markov chain model. By analyzing the time-dependent and the steady-state probabilities of the Markov chain, we obtain risk measures such as the probability of casualty at a given location and also the expected number of casualties for a given number of vessels arriving per unit time. Analysis of the Markovian model also yields an analytical result that shows that the expected number of casualties is proportional to square of the tanker arrival rate. We present our methodology on an experimental model of a hypothetical narrow waterway. © 1999 John Wiley & Sons, Inc. Naval Reseach Logistics 46: 871–892, 1999