Models for production planning under power interruptions

We present a robust optimization model for production planning under the assumption that electricity supply is subject to uncertain interruptions caused by participation in interruptible load contracts (ILCs). The objective is to minimize the cost of electricity used for production while providing a robust production plan which ensures demand satisfaction under all possible interruption scenarios. The combinatorial size of the set of interruption scenarios makes this a challenging problem. Furthermore, we assume that no probabilistic information is known about the supply uncertainty: we only use the information given in the ILC to identify an uncertainty set that captures the possible scenarios. We construct a general robust framework to handle this uncertainty and present a heuristic to compute a good feasible solution of the robust model. We provide computational experiments on a real‐world example and compare the performance of an exact solver applied to the robust model with that of the heuristic procedure. Finally, we include the operational impact of interruptions such as “recovery modes” in the definition of the uncertainty set. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

Beyond the Double Game: Lessons from Pakistan’s Approach to Islamist Militancy

States commonly take one of three approaches to militant groups on their soil: collaboration; benign neglect; or belligerence. All three approaches are present in Pakistan, where some groups also move back and forth among these categories. I employ the term “coopetition” to capture this fluidity. The dynamic nature of militancy in Pakistan makes the country an excellent laboratory for exploring a state’s assessment of the utility an Islamist militant group offers, and the threat it poses relative to other threats informs the state’s treatment of that group. In this article, I put forward a typology that situates Islamist militants in Pakistan in one of the above four categories. I also illustrate how a group’s identity, objectives, and alliances inform assessments of its utility and threat relative to other threats. In addition to enhancing our understanding of militant–state dynamics, this taxonomy builds on and helps to unify earlier typologies of Pakistani militancy.     

How Is a Man to Decide? Unjust Combatants,Duress and McMahan’s Killing in War

Jeff McMahan’s much-discussed work Killing in War is an important part of the revisionist school of just war studies. This paper avoids discussion of McMahan’s use of human rights and examines the practical consequences of his argument about duress on soldiers to fight an unjust war. These arguments are found to be wanting and to be impractical ones that do not fit battlefield realities. The importance of the Law of Armed Conflict and the legal equality of combatants that is part of it is emphasised and accepted as the most practical way of regulating battlefield behaviour and saving lives. It is concluded that attempts to tell soldiers what to do when they may be fighting an unjust war add to their burdens and are misplaced.