Selecting review periods for a coordinated multi‐item inventory model with staggered deliveries

Consider an N‐item, periodic review, infinite‐horizon, undiscounted, inventory model with stochastic demands, proportional holding and shortage costs, and full backlogging. For 1 ≤ j ≤ N, orders for item j can arrive in every period, and the cost of receiving them is negligible (as in a JIT setting). Every T_j periods, one reviews the current stock level of item j and decides on deliveries for each of the next T_j periods, thus incurring an item‐by‐item fixed cost k_j. There is also a joint fixed cost whenever any item is reviewed. The problem is to find review periods T₁, T₂, …, T_N and an ordering policy satisfying the average cost criterion. The current article builds on earlier results for the single‐item case. We prove an optimal policy exists, give conditions where it has a simple form, and develop a branch and bound algorithm for its computation. We also provide two heuristic policies with O(N) computational requirements. Computational experiments indicate that the branch and bound algorithm can handle normal demand problems with N ≤ 10 and that both heuristics do well for a wide variety of problems with N ranging from 2 to 200; moreover, the performance of our heuristics seems insensitive to N. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48:430–449, 2001     

Automated air load planning

We describe the development of a heuristic algorithm for determining efficient 2-dimensional packings in cargo aircraft where cargo placement constraints are critically important in determining the feasibility of packing locations. We review the performance of a new algorithm versus some traditional ones for aircraft loading. The algorithm is also tested in a more generalized setting where there exist no additional constraints on items, to suggest applicability in other environments. The new algorithm has been used worldwide in the Automated Air Load Planning System (AALPS) for cargo aircraft loading, with much success. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 751–768, 1998     

The customer order lead-time problem on parallel machines

We consider the problem of scheduling customer orders, each consisting of one or more individual jobs, on a set of parallel processors with the objective of minimizing average order completion time. We provide simple intuitive heuristics to guide managers in this environment and introduce lower bounds that show that these heuristics are effective for a wide variety of problems. © 1996 John Wiley & Sons, Inc.     

Between the Cracks: Actor Fragmentation and Local Conflict Systems in the Libyan Civil War

Abstract

After nearly four years of civil war, Libya continues to be described as an ‘ungoverned space’ where the collapse of state institutions reignited tribal, political, religious and ideological tensions. These accounts, however, obscure Libya’s complex subnational governance, and the role of non-state armed groups in shaping the emerging political orders. By contrast, we contend that distinct subnational political orders have emerged in Libya since 2014 in which actors engage in state-making practices driven by local interests. Using empirical evidence to explore the activity of non-state armed groups during the Libyan civil conflict, we highlight that the local conflict environments in eastern, western and southern Libya provide specific incentives that shape the process of armed group splintering and patterns of violence. The findings demonstrate that claims to authority and notions of statehood extend far beyond the state whereby governance relations are negotiated between state and non-state actors. Conflict patterns, (in)stability and the prevailing political order are therefore conditional on the nature of the dominant actor, their strategies and modes of violence within their areas of influence. Through this analysis, the paper provides a more granular understanding of the local political dynamics that drive violence in Libya and civil wars more generally.     

Reclaiming the Party’s Control of the Gun: Bringing Civilian Authority Back in China’s Civil-Military Relations

ABSTRACT

Since emerging as China’s top leader following the 18th Party Congress, Xi Jinping has moved swiftly to consolidate his formal authority as Central Military Commission chairman over the Chinese People’s Liberation Army. In redressing the civil-military imbalance wrought by Dengist economic reforms, the commander-in-chief has combined institutional mechanisms with the use of fear to impose authoritative civilian control over the military. This paper proposes that a combination of changes to the Chinese strategic environment has contributed to Xi’s utility of the anti-corruption campaign to purge the regime’s coercive forces of its previous underpinnings, and advances that the war on military malfeasance has given rise to a new set of dynamics in civil-military relations in post-Reform China.     

Ethnic groups,political exclusion and domestic terrorism

This study examines whether the exclusion of ethnic groups from political power is an important contributing factor to domestic terrorism. To empirically test this question, we employ a negative binomial regression estimation on 130 countries during the period from 1981 to 2005. We find that countries in which certain ethnic populations are excluded from political power are significantly more likely to experience domestic terrorist attacks and to suffer from terrorist casualties; furthermore, ethnic group political exclusion is a more consistent and substantive predictor of domestic terrorist activity than general political repression or economic discrimination.