Dual‐ascent and primal heuristics for production‐assembly‐distribution system design

This article proposes two dual‐ascent algorithms and uses each in combination with a primal drop heuristic embedded within a branch and bound framework to solve the uncapacitated production assembly distribution system (i.e., supply chain) design problem, which is formulated as a mixed integer program. Computational results indicate that one approach, which combines primal drop and dual‐ascent heuristics, can solve instances within reasonable time and prescribes solutions with gaps between the primal and dual solution values that are less than 0.15%, an efficacy suiting it for actual large‐scale applications. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

Thailand and the Insurgency in the South

The insurgency in southern Thailand has proven to be intractable over the last few years. The insurgents, who comprise several different groups, have largely retained the initiative in a series of relatively unsophisticated operations. Although involving ethnic Malay Muslims – and marked by an increasingly strong Islamist ideology – the insurgency has been predominantly ethnic rather than religious. External jihadist involvement has been minimal at best. The recent coup in Thailand may improve the odds of reaching some form of accommodation with the southern insurgents; but it is likely that the south will remain a continuing security problem for Bangkok.     

Insurgency in amber: ethnic opposition groups in Myanmar

Multiple ethnic insurgencies have existed in Myanmar since independence. The military junta's response has been extremely brutal at the tactical level, but has shown some political astuteness at the strategic level, with a series of ceasefires with most of the ethnic groups. Despite these ceasefires – most of which have resulted in the continued existence of quasi-independent armed groups – other ethnic movements have continued their armed operations. The overall strategic picture is one of stalemate, with the ethnic movements continuing to exist, but with few realistic prospects of expanding their operations.     

The Insurgency Environment in Northeast India

The northeast states of India have faced a series of insurgencies almost since independence. Most insurgent groups have been based on the competing demands of various ethnic groups, with conflicts not only between the insurgents and the government, but also between groups. The combination of anti-government and intercommunal violence shows little sign of ending. Although the Indian government has made progress in dealing with the largest groups, the continued existence of several dozen insurgent movements represents a significant security threat to internal stability in India.     

On the Road to the 2015 NPT Review Conference

The second session of the Preparatory Committee for the 2015 Review Conference (RevCon) of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) highlighted two issues in particular—progress toward a Middle East Weapons of Mass Destruction–Free Zone and the Joint Statement on the humanitarian impact of nuclear weapons—that may not only greatly affect the health and vitality of the NPT and the 2015 RevCon, but possibly also have implications for the international nonproliferation regime as a whole. Dr. William Potter, director of the James Martin Center for Nonproliferation Studies, interviewed Ambassador Cornel Feruta, chairman of the 2013 PrepCom, to discuss these and other issues related to the meeting and the future of the treaty and its review process.     

Bounding methods for facilities location algorithms

Single- and multi-facility location problems are often solved with iterative computational procedures. Although these procedures have proven to converage, in practice it is desirable to be able to compute a lower bound on the objective function at each iteration. This enables the user to stop the iterative process when the objective function is within a prespecified tolerance of the optimum value. In this article we generalize a new bounding method to include multi-facility problems with l_p distances. A proof is given that for Euclidean distance problems the new bounding procedure is superior to two other known methods. Numerical results are given for the three methods.     

Optimal selection with alternative information

This article examines the problem of optimally selecting from several unknown rewards when there are given alternative, costly sources of information. The optimal rule, indicating the information to be purchased and the reward to be selected, is specified as a function of the decision maker's prior probabilities regarding the value of each alternative. The rule is surprisingly complex, balancing prior beliefs, the “informativeness” of the relevant information system, and the cost of acquiring information.     

The asymptotic joint distribution of the state occupancy times in an alternating renewal process

An alternating renewal process starts at time zero and visits states 1,2,…,r, 1,2, …,r 1,2, …,r, … in sucession. The time spent in state i during any cycle has cumulative distribution function F_i, and the sojourn times in each state are mutually independent, positive and nondegenerate random variables. In the fixed time interval [0,T], let U_i(T) denote the total amount of time spent in state i. In this note, a central limit theorem is proved for the random vector (U_i(T), 1 ≤ i ≤ r) (properly normed and centered) as T → ∞.