Interchange fees for bank ATM networks

Banks have found it advantageous to connect their Automated Teller Machines (ATMs) in networks so that customers of one bank may use the ATMs of any bank in the network. When this occurs, an interchange fee is paid by the customer's bank to the one that owns the ATM. These have been set by historic interbank negotiation. The paper investigates how a model based on n-player game theory concepts of Shapley value and nucleolus could be used as an alternative way of setting such fees. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 407–417, 1998     

Restricted planar location problems and applications

Facility location problems in the plane are among the most widely used tools of Mathematical Programming in modeling real-world problems. In many of these problems restrictions have to be considered which correspond to regions in which a placement of new locations is forbidden. We consider center and median problems where the forbidden set is a union of pairwise disjoint convex sets. As applications we discuss the assembly of printed circuit boards, obnoxious facility location and the location of emergency facilities. © 1995 John Wiley & Sons, Inc.     

Asymptotically optimal linear time algorithms for two‐stage and three‐stage flexible flow shops

We consider two‐stage and three‐stage flexible flow shops with parallel machines in each stage and the minimum makespan objective. We develop linear time algorithms for these problems with absolute worst‐case bounds either sharper or no worse than the currently available ones and we accomplish this with lower complexity algorithms. We also demonstrate the asymptotic optimality of a class of algorithms for multistage flexible flow shop problems (which includes the proposed algorithms) under certain probabilistic assumptions on the job processing times. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 259–268, 2000     

Repression Substitution: Shifting Human Rights Violations in Response to UN Naming and Shaming

Does the United Nations naming and shaming of specific violations of human rights decrease government repression? In this article, we argue that international shaming of specific human rights violations can weaken the target government, bringing new challenges and making the government cessation of repression less feasible. When international naming and shaming campaigns target specific repressive tactics, they increase the costs of some – but not all – means of repression. Using original data on naming and shaming by the United Nations Human Rights Council (HRC), we show that the shaming of one physical integrity violation is jointly associated with decreases in that violation and increases in other violations of human rights.     

Optimal policies for stochastic clearing systems with time-dependent delay penalties

We study stochastic clearing systems with a discrete-time Markovian input process, and an output mechanism that intermittently and instantaneously clears the system partially or completely. The decision to clear the system depends on both quantities and delays of outstanding inputs. Clearing the system incurs a fixed cost, and outstanding inputs are charged a delay penalty, which is a general increasing function of the quantities and delays of individual inputs. By recording the quantities and delays of outstanding inputs in a sequence, we model the clearing system as a tree-structured Markov decision process over both a finite and infinite horizon. We show that the optimal clearing policies, under realistic conditions, are of the on-off type or the threshold type. Based on the characterization of the optimal policies, we develop efficient algorithms to compute parameters of the optimal policies for such complex clearing systems for the first time. We conduct a numerical analysis on the impact of the nonlinear delay penalty cost function, the comparison of the optimal policy and the classical hybrid policy (ie, quantity and age thresholds), and the impact of the state of the input process. Our experiments demonstrate that (a) the classical linear approximation of the cost function can lead to significant performance differences; (b) the classical hybrid policy may perform poorly (as compared to the optimal policies); and (c) the consideration of the state of the input process makes significant improvement in system performance.     

Violence in context: Mapping the strategies and operational art of irregular warfare

The malaise that the United States, and the West, have experienced in recent campaigns stems in large part from unclear thinking about war, its political essence, and the strategies needed to join the two. Instead, analysis and response are predicated on entrenched theoretical concepts with limited practical utility. The inadequacy of understanding has spawned new, and not so new, terms to capture unanticipated trends, starting with the re-discovery of “insurgency” and “counterinsurgency” and leading to discussion of “hybrid threats” and “gray-zone” operations. New terminology can help, but the change must go deeper. Challenging analytical orthodoxy, this article sets out a unifying approach for the study of political violence, or more accurately: violent politics. It provides a conceptual foundation that helps to make sense of recent shifts in warfare. In effect, it offers sorely needed theoretical insights into the nature of strategy and guides the process of responding to nontraditional threats.     

A multiechelon inventory model with multiple failures

This article presents a recoverable spares model for performance evaluation in a multiechelon inventory environment. This model explicitly incorporates the phenomenon known as multiple failures, in which more than one part can require replacement or repair when an end-item reaches a maintenance base. The model is shown to be computationally intractable, and an approximation scheme is presented to estimate system performance. © 1993 John Wiley & Sons, Inc.     

Evaluation of base-stock policies in multiechelon inventory systems with state-dependent demands part I: State-independent policies

This article analyzes a model of a multiechelon inventory system. The exogenous demands form Markov-modulated Poisson processes. That is, the demand rates are functions of an underlying Markov chain. Each location follows a base-stock policy which is independent of the state of the underlying Markov chain. We employ the exogenous transit mechanism introduced by Zipkin [7] and Svoronos and Zipkin [6]. The transit times between locations have phase-type distributions. An exact procedure to compute steady-state performance measures is presented. © 1992 John Wiley & Sons, Inc.     

Estimation of the survival function of a repairable standby series system

This article deals with the statistical analysis of an N-component series system supported by an active standby and one repair facility. Assuming that the life and repair times of the components are independent exponential random variables, the probability distribution of the first passage to the system failure time is shown to be a convolution of two independent exponential distributions. Three observation schemes are considered to obtain the maximum likelihood estimates of the survival function. Information matrices are supplied. Numerical results based on Monte Carlo simulation are presented. It is noted that component level information (failure rate, repair rate) is not necessary for estimating the survival function of the system.