Why provoke? the Sino-US competition in East Asia and North Korea’s strategic choice

This article seeks to make sense of North Korean provocations in light of the Sino-US strategic competition in post-Cold War East Asia, where such variables as China’s rise, US’s pivot to Asia, and growing Sino-ROK economic ties are driving the strategic choices of major states in the region. The article examines the main motivations behind Pyongyang’s provocations since the end of the Cold War, discusses their implications for the Sino-US strategic competition in East Asia, and offers predictions about the future of North Korean provocations. The central thesis of the article is that Pyongyang has exploited the Sino-US strategic competition in East Asia for its regime survival. By raising North Korea’s strategic value to China, the intensifying Sino-US competition allows Pyongyang to continue provocations, regardless of Beijing’s explicit opposition.     

Effect of change of sand properties on travel distance of ricocheted debris

The debris from exploded buildings can ricochet after colliding with the ground, thus increasing the debris travel distance and danger from any associated impacts or collisions. To reduce this danger, the travel distance of ricocheted debris must be accurately predicted. This study analyzed the change in the travel distance of ricocheted concrete debris relative to changes in the properties of a sand medium. Direct shear tests were conducted to measure the change in internal friction angle as a function of temperature and water content of the sand. Finite element analysis (FEA) was then applied to these variables to predict the speed and angle of the debris after ricochet. The FEA results were compared with results of low-speed ricochet experiments, which employed variable temperature and water content. The travel distance of the debris was calculated using MATLAB, via trajectory equations considering the drag coefficient. As the internal friction angle decreased, the shear stress decreased, leading to deeper penetration of the debris into the sand. As the loss of kinetic energy increased, the velocity and travel distance of the ricocheted debris decreased. Changes in the ricochet velocity and travel distance of the debris, according to changes in the internal friction angle, indicated that the debris was affected by the environment.     

Bounds for strength-stress interference via mathematical programming

Problems of bounding Pr {X > Y}, when the distribution of X is subject to certain moment conditions and the distribution of Y is known to be of convexconcave type, are treated in the framework of mathematical programming. Juxtaposed are two programming methods; one is based on the notion of weak duality and the other on the geometry of a certain moment space.     

An economic selective assembly procedure for two mating components with equal variance

An economic procedure of selective assembly is proposed when a product is composed of two mating components. The major quality characteristic of the product is the clearance between the two components. The components are divided into several classes prior to assembly. The component characteristics are assumed to be independently and normally distributed with equal variance. The procedure is designed so that the proportions of both components in their corresponding classes are the same. A cost model is developed based on a quadratic loss function and methods of obtaining the optimal class limits as well as the optimal number of classes are provided. Formulas for obtaining the proportion of rejection and the unavailability of mating components are also provided. The proposed model is compared with the equal width and the equal area partitioning methods using a numerical example. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 809–821, 1999     

The evaluation of a possible future Sino-Japanese armed conflict through the application of the ACEI-model

There is relatively little formal modeling of the economic effects of armed conflicts even though they have substantial economic effects. We set forth a new model, namely the armed conflict economic impact model – ACEI-Model. The model looks at the economic effects of war in three different stages: (i) pre-conflict stage; (ii) armed conflict stage; and (iii) post-conflict stage. The model is based on economic desgrowth (-δ) and other new conceptual indicators. We evaluate an imaginary armed conflict between China and Japan by applying the ACEI-Model.     

Heuristic algorithms for routing yard‐side equipment for minimizing loading times in container terminals

This paper discusses a method of routing yard‐side equipment during loading operations in container terminals. Both the route of yard‐side equipment (such as transfer cranes or straddle carriers) and the number of containers picked up at each yard‐bay is determined simultaneously. The objective of the problem in this paper is to minimize the total container‐handling time in a yard. The size of the search space can be greatly reduced by utilizing inherent properties of the optimal solution. An encoding method is introduced to represent solutions in the search space. A genetic algorithm and a beam search algorithm are suggested to solve the above problem. Numerical experiments have been conducted to compare the performances of the proposed heuristic algorithms against each other and against that of the optimal solution. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 498–514, 2003     

State information lag markov decision process with control limit rule

In the framework of a discrete Markov decision process with state information lag, this article suggests a way for selecting an optimal policy using the control limit rule. The properties sufficient for an optimal decision rule to be contained in the class of control limit rules are also studied. The degradation in expected reward from that of the perfect information process provides a measure of the potential value of improving the information system.     

The (s,Q) inventory model with Erlang lead time and deterministic demand

We develop a simple, approximately optimal solution to a model with Erlang lead time and deterministic demand. The method is robust to misspecification of the lead time and has good accuracy. We compare our approximate solution to the optimal for the case where we have prior information on the lead‐time distribution, and another where we have no information, except for computer‐generated sample data. It turns out that our solution is as easy as the EOQ's, with an accuracy rate of 99.41% when prior information on the lead‐time distribution is available and 97.54–99.09% when only computer‐generated sample information is available. Apart from supplying the inventory practitioner with an easy heuristic, we gain insights into the efficacy of stochastic lead time models and how these could be used to find the cost and a near‐optimal policy for the general model, where both demand rate and lead time are stochastic. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

Dynamic proximity calculations for situation awareness

We apply dynamic proximity calculations (density and clustering) from dynamic computational geometry to a military application. The derived proximity information serves as an abstract view of a current situation in the battlefield that can help a military commander achieve situation awareness. We employ Delaunay triangulation as a computational tool in our framework, and study its dynamic update in depth. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004.     

Network disconnection problems in a centralized network

We consider three network disconnection problems in a centralized network where a source node provides service to the other nodes, called demand nodes. In network disconnection problems, each demand node gets a certain benefit when connected to a source node and a network attacker destroys edges to prevent demand nodes from achieving benefits. As destroying edges incurs expenses, an attacker considers the following three different strategies. The first is to maximize the sum of benefits of the disconnected nodes while keeping the total edge destruction cost no more than a given budget. The second is to minimize the total destruction cost needed to make a certain amount of benefits not accomplished. The last is to minimize the ratio of the total destruction cost to the benefits not accomplished. In this paper, we develop exact algorithms to solve the above three problems. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007