Optimal control policies for a periodic review inventory system with emergency orders

We describe a periodic review inventory system where emergency orders, which have a shorter supply lead time but are subject to higher ordering cost compared to regular orders, can be placed on a continuous basis. We consider the periodic review system in which the order cycles are relatively long so that they are possibly larger than the supply lead times. Study of such systems is important since they are often found in practice. We assume that the difference between the regular and emergency supply lead times is less than the order-cycle length. We develop a dynamic programming model and derive a stopping rule to end the computation and obtain optimal operation parameters. Computational results are included that support the contention that easily implemented policies can be computed with reasonable effort. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 187–204, 1998     

20世纪六七十年代中国战备指导思想浅析

新中国成立后,一直面临着帝国主义的封锁、包围和战争威胁.特别是进入20世纪60年代中期以后,随着中国周边安全环境的日益恶化,新中国领导人开始强调要准备打仗,提出并确立立足于"早打、大打、打核战争"的战备指导思想.     

The timing of third-party intervention in social conflict

This paper analyzes how the equilibrium outcome of social conflict between factions is strategically altered by third-party intervention. We consider an intervening third party that commits financial support to one of two contending factions for reducing its cost in conflict. Within the framework of three-player sequential-move games, we investigate the questions as follows. What is the optimal intervention intensity in terms of the third party’s financial support? Is there a first-mover advantage in conflict when there is third-party intervention? Fighting against all odds, will the unsupported faction have a chance to prevail when its opponent receives third-party support? What is the optimal timing of third-party intervention? The analysis in the paper has implications for the conditions under which the strategic intervention of a third party may or may not break a conflict between factions.     

基于扩展贝叶斯理论的装备维修保障系统效能评估

针对多源评估数据融合问题,通过对传统贝叶斯理论进行扩展,提出了一种在考虑指标数据可信度影响下维修保障系统效能的多源评估数据融合模型.该模型利用Vague集的隶属与非隶属性关系描述指标数据的可信度与不可信度,通过建立指标数据可信度Vague集与理想Vague集的相似度函数获得指标可信度的量化值,并通过扩晨贝叶斯理论将包含...     

Robust cubature Kalman filter method for the nonlinear alignment of SINS

Nonlinear initial alignment is a significant research topic for strapdown inertial navigation system(SINS).Cubature Kalman filter(CKF)is a popular tool for nonlinear initial alignment.Standard CKF assumes that the statics of the observation noise are pre-given before the filtering process.Therefore,any unpredicted outliers in observation noise will decrease the stability of the filter.In view of this problem,improved CKF method with robustness is proposed.Multiple fading factors are introduced to rescale the obser-vation noise covariance.Then the update stage of the filter can be autonomously tuned,and if there are outliers exist in the observations,the update should be less weighted.Under the Gaussian assumption of KF,the Mahalanobis distance of the innovation vector is supposed to be Chi-square distributed.Therefore a judging index based on Chi-square test is designed to detect the noise outliers,determining whether the fading tune are required.The proposed method is applied in the nonlinear alignment of SINS,and vehicle experiment proves the effective of the proposed method.     

Statistical equivalency and optimality of simple step‐stress accelerated test plans for the exponential distribution

Accelerated life testing (ALT) is commonly used to obtain reliability information about a product in a timely manner. Several stress loading designs have been proposed and recent research interests have emerged concerning the development of equivalent ALT plans. Step‐stress ALT (SSALT) is one of the most commonly used stress loadings because it usually shortens the test duration and reduces the number of required test units. This article considers two fundamental questions when designing a SSALT and provides formal proofs in answer to each. Namely: (1) can a simple SSALT be designed so that it is equivalent to other stress loading designs? (2) when optimizing a multilevel SSALT, does it degenerate to a simple SSALT plan? The answers to both queries, under certain reasonable model assumptions, are shown to be a qualified YES. In addition, we provide an argument to support the rationale of a common practice in designing a SSALT, that is, setting the higher stress level as high as possible in a SSALT plan. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

Revisiting the Defense–Growth nexus in European countries

This study revisits the long run and dynamic causal linkages between defense spending and economic growth in 15 selected European countries for the period 1988–2010 by utilizing recent developments in non-stationary panel data analysis. To this end, the series properties of per capita defense spending, per capita real capita stocks, and per capita real GDP are investigated by the panel unit root tests with and without breaks that support evidence on unit root. The panel cointegration tests with and without breaks are also subsequently employed to investigate whether there exists a long-run equilibrium relationship between these three variables. Finally, our causality analysis from panel vector error-correction model suggests that there is a feedback relation between real capital stock and real GDP in both short and long run, a one-way Granger causality running from real GDP to defense spending in both short and long run, and defense spending only Granger causes real capital stock in the long run.     

Defence expenditures and economic growth: The externality effect

In a series of articles published in the Fall 1990 issue of Defence Economics Alexander (1990), Atesoglu and Mueller (1990) and Huang and Mintz (1990) have all specified and empirically estimated defence‐growth models based on a neoclassical production function. We now isolate the externality component in our model, re‐estimate its coefficients using data on the U.S. economy 1952–88 and compare specifications and results with Atesoglu and Mueller (1990) and Alexander (1990).