Predictability of operational processes over finite horizon

Operational processes are usually studied in terms of stochastic processes. The main information measure used for predictability of stochastic processes is the entropy rate, which is asymptotic conditional entropy, thus not suitable for application over a finite horizon. We use the conditional entropy to study the predictability of stochastic processes over the finite horizon. It is well‐known that the conditional entropies of stationary processes decrease as the processes evolve, implying that, on average, their pasts become more informative about prediction of their future outcomes. Some important operational processes such as martingale, models for maintenance policies, nonhomogeneous Poisson, and mixed Poisson processes are nonstationary. We show that as a nonstationary process evolves, it may provide more information or less information about the future state of the system. We develop results for comparing the predictability of stochastic processes. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

军事文化:一个范式的转换(节选)

本篇译稿节选了美国空军中校卡伦·O·杜尼文《军事文化——一个范式的转换?》一书的部分内容,作者考察了美国军事文化中的社会性变化,探究了美国军事文化中一种介于军事的传统与非传统之间的,介于男性战士为主的范式或信仰体系和以平等主义与兼容并蓄为特征的充满矛盾的进化军事文化模式之间的斗争。这是一场旧思想和新思想之间的竞赛。译者选编了作者战斗部队中的女性(战争中的女性)这一典型案例来阐述美国军事文化中范式与模式之间的差异。杜尼文中校在本书中还考察了美国军事文化中存在的长期冲突,她建议美国军方现在开始需再一次进行文化范式的转换———从传统的以男性士兵为主的排他性价值观向一种兼容并蓄的从军观念转变。作者强调美国军方必须在其发展过程中,削减其分离主义和排外性的倾向。她提出实施这一范式转换的三个对策(战略部署):改变军方的占主导地位的关于“战斗着的,充满阳刚之气”的具有排他性而非包容性的标准和想法;主动接受并控制正在持续的主要的社会性变化;同时接受与个人和组织对范式转换的职责。范式转换的先驱们必须特别地推崇一种兼容并蓄与平等主义的文化。杜尼文中校也强调了美国高级军事将领是产生美国军事范式转换的最佳催化剂———他们是真正的先驱,他们能够使兼容并蓄的文化范式制度化。杜尼文中校提出如下结论:如果美国希望其军方成为美国社会的一面镜子,无疑要接受一种兼容并蓄的文化范式。     

Vertically restrictive pricing in supply chains with price‐dependent demand

We examine the behavior of a manufacturer and a retailer in a decentralized supply chain under price‐dependent, stochastic demand. We model a retail fixed markup (RFM) policy, which can arise as a form of vertically restrictive pricing in a supply chain, and we examine its effect on supply chain performance. We prove the existence of the optimal pricing and replenishment policies when demand has a linear additive form and the distribution of the uncertainty component has a nondecreasing failure rate. We numerically compare the relative performance of RFM to a price‐only contract and we find that RFM results in greater profit for the supply chain than the price‐only contract in a variety of scenarios. We find that RFM can lead to Pareto‐improving solutions where both the supplier and the retailer earn more profit than under a price‐only contract. Finally, we compare RFM to a buyback contract and explore the implications of allowing the fixed markup parameter to be endogenous to the model. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.     

Noise and vibration measurements in a Viking military vehicle

Noise and whole-body vibration measurements were made in a Viking military vehicle to determine the variation that should be expected during repeat measures, the effect of speed (up to 60 km/h in 5 km/h increments), and during travel over different types of terrain (comprising concrete road, gravel track and rough cross-country). Measurements were made at various crew positions (including the driver and commander) in both the front and the rear cabs in the vehicles. Three translational axes of vibration were measured in each seat. Two speeds were investigated over road (35 km/h and 55–60 km/h) and gravel (20 km/h and 35 km/h) surfaces. The effect of varying speed of the vehicle on the measured noise and vibration magnitudes was also investigated. The highest sound pressure level (L_Aeq) of 104 dB(A) was measured at the commander’s standing position during travel over concrete road at 55 km/h. Higher noise levels occurred for a standing commander compared with when sitting on the seat. A maximum single axis frequency-weighted vibration magnitude of 1.0 m/s² r.m.s. was measured on the driver’s seat during travel over track at 35 km/h. Higher vibration magnitudes occurred during travel over track compared with travel over road. Both noise and vibration exposure of crew within the Viking vehicle increased with increasing speed of the vehicle.     

Influence of porosity distribution on nonlinear free vibration and transient responses of porous functionally graded skew plates

This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew (PFGS) plates. The effective material properties of the PFGS plates are obtained from the modified power-law equations in which gradation varies through the thickness of the PFGS plate. A nonlinear finite element (FE) formulation for the overall PFGS plate is derived by adopting first-order shear deformation theory (FSDT) in conjunction with von Karman’s nonlinear strain displacement relations. The governing equations of the PFGS plate are derived using the principle of virtual work. The direct iterative method and Newmark’s integration technique are espoused to solve nonlinear mathematical relations. The influences of the porosity distributions and porosity parameter indices on the nonlinear frequency responses of the PFGS plate for different skew angles are studied in various parameters. The effects of volume fraction grading index and skew angle on the plate’s nonlinear dynamic responses for various porosity distributions are illustrated in detail.     

Mitigation of the blast load effects on a building structure using newly composite structural configurations

In this study, a nonlinear three-dimensional hydrocode numerical simulation was carried out using AUTODYN-3D to investigate the effect of blasting of a high explosive material (TNT) against several configurations of the composite structure. Several numerical models were carried out to study the effect of varying the thickness of the walls and the effect of adding an air layer or aluminum foam layer inside two layers of concrete in mitigating the effect of blast waves on the structure walls. The results showed that increasing the thickness of walls has a good effect on mitigating the effect of blast waves. When a layer of air was added, the effect of blast waves was exaggerated, while when a layer of aluminum foam was added the blast wave effects were mitigated with a reasonable percentage.     

From management crisis to crisis management? Japan’s post-2012 institutional reforms and Sino-Japanese crisis (In)stability

Since 2012, China’s assertion of its sovereignty claim to the contested Senkaku/Diaoyu Islands has significantly raised the risk of a potentially escalatory political-military crisis with Japan. As circumstances worsen, Japanese Prime Minister Shinzo Abe has championed major institutional reforms aimed at centralizing Japanese security policy decision-making and vastly improving crisis management. This article assesses these reforms’ significance for ameliorating Japan’s long-standing internal crisis management weaknesses, and enhancing its ability to communicate with Beijing promptly under challenging conditions. While significant issues remain, recent developments – especially the establishment of Japan’s first-ever National Security Council – demonstrate significant progress. Bilaterally, however, important firebreaks remain conspicuously absent.     

Shifting power,preventive logic,and the response of the target: Germany,Russia, and the First World War

If a declining state has incentives for preventive war, the rising state should have incentives to delay a confrontation until it is stronger. We develop the theoretical paradox and examine the July 1914 crisis. Why did Russia, rising relative to Germany, not adopt a buying-time strategy? We argue that although most Russian leaders hoped to avoid a confrontation, they feared that the failure to support Serbia would lead to a loss of Russian credibility and a significant setback to Russia’s position in the Balkans, one that could not easily be reversed, even with Russia’s expected increase in relative military power.     

Note: Facility location with closest rectangular distances

This paper considers the problem of locating one or more new facilities on a continuous plane, where the destinations or customers, and even the facilities, may be represented by areas and not points. The objective is to locate the facilities in order to minimize a sum of transportation costs. What is new in this study is that the relevant distances are the distances from the closest point in the facility to the closest point in the demand areas. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 77–84, 2000