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We consider the Capacitated Traveling Salesman Problem with Pickups and Deliveries (CTSPPD). This problem is characterized by a set of n pickup points and a set of n delivery points. A single product is available at the pickup points which must be brought to the delivery points. A vehicle of limited capacity is available to perform this task. The problem is to determine the tour the vehicle should follow so that the total distance traveled is minimized, each load at a pickup point is picked up, each delivery point receives its shipment and the vehicle capacity is not violated. We present two polynomial‐time approximation algorithms for this problem and analyze their worst‐case bounds. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 654–670, 1999 相似文献
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Julien Malizard 《Defence and Peace Economics》2014,25(6):635-642
France has received little attention in the literature of defense economics, despite some outstanding features of the country’s situation. This study attempts to partially fill this gap with new empirical evidence which evaluates the influence of military expenditure on the unemployment rate between 1975 and 2008. Our estimation is based on the ARDL approach to cointegration. The results reveal that both defense and non-defense spending exert a negative influence on unemployment but that defense spending has a higher negative impact. 相似文献
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Julien Malizard 《Defence and Peace Economics》2019,30(2):129-132
The French defense policy has been considered unique among western countries. This policy relies on the concept of ‘strategic autonomy’, which is based on nuclear deterrence, autonomy of action, independence of defense industry, and arms exports. From an economic perspective, it implies major consequences both at the macroeconomic and microeconomic levels. Given its importance, it is crucial to use economic expertise to provide insights on defense policy. 相似文献
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We consider a version of the famous bin-packing problem where the cost of a bin is a concave function of the number of items in the bin. We analyze the problem from an average-case point of view and develop techniques to determine the asymptotic optimal solution value for a variety of functions. We also describe heuristic techniques that are asymptotically optimal. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 673–686, 1997 相似文献
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We consider the Inventory‐Routing Problem (IRP) where n geographically dispersed retailers must be supplied by a central facility. The retailers experience demand for the product at a deterministic rate, and incur holding costs for keeping inventory. Distribution is performed by a fleet of capacitated vehicles. The objective is to minimize the average transportation and inventory costs per unit time over the infinite horizon. We focus on the set of Fixed Partition Policies (FPP). In an FPP, the retailers are partitioned into disjoint and collectively exhaustive sets. Each set of retailers is served independently of the others and at its optimal replenishment rate. Previous research has measured the effectiveness of an FPP solution relative to a lower bound over all policies. We propose an additional measure that is relative to the optimal FPP. In this paper we construct a polynomial‐time partitioning scheme that is shown to yield an FPP whose cost is asymptotically within 1.5% + ? of the cost of an optimal FPP, for arbitrary ? > 0. In addition, in some cases, our polynomial‐time scheme yields an FPP whose cost is asymptotically within 1.5% + ? of the minimal policy's cost (over all feasible policies). © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004 相似文献
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The aim of this article is to evaluate how French Major Conventional Weapons (MCW) exports impact on the conflict intensity of recipient countries. The recent increase in French arms exports seems to contradict the French political discourse on the promotion of regional stability. We run zero-inflated ordered probit model in order to analyze the role of the arms trade on the intensity of civil conflicts in 144 countries from 1992 to 2014, using SIPRI and UCDP/PRIO data. Our results suggest that French MCW exports tended not to exacerbate intrastate conflicts during this period. This finding is robust to changes in the empirical framework. We propose two lines of explanations: France seems to be prone to choosing partners that respect human rights and selling more ‘defense-oriented’ MCW than the rest of the world. 相似文献
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