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Inventory models with nonlinear shortage costs and stochastic lead times; applications of shape properties of randomly stopped counting processes 下载免费PDF全文
In this article, we study generalizations of some of the inventory models with nonlinear costs considered by Rosling in (Oper. Res. 50 (2002) 797–809). In particular, we extend the study of both the periodic review and the compound renewal demand processes from a constant lead time to a random lead time. We find that the quasiconvexity properties of the cost function (and therefore the existence of optimal (s, S) policies), holds true when the lead time has suitable log‐concavity properties. The results are derived by structural properties of renewal delayed processes stopped at an independent random time and by the study of log‐concavity properties of compound distributions. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 345–356, 2015 相似文献
603.
The dynamic and stochastic knapsack Problem with homogeneous‐sized items and postponement options 下载免费PDF全文
This article generalizes the dynamic and stochastic knapsack problem by allowing the decision‐maker to postpone the accept/reject decision for an item and maintain a queue of waiting items to be considered later. Postponed decisions are penalized with delay costs, while idle capacity incurs a holding cost. This generalization addresses applications where requests of scarce resources can be delayed, for example, dispatching in logistics and allocation of funding to investments. We model the problem as a Markov decision process and analyze it through dynamic programming. We show that the optimal policy with homogeneous‐sized items possesses a bithreshold structure, despite the high dimensionality of the decision space. Finally, the value (or price) of postponement is illustrated through numerical examples. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 267–292, 2015 相似文献
604.
Isabelle Côté 《Civil Wars》2015,17(3):357-378
Why are large population movements conflict-prone in some regions while they remain peacefully integrated elsewhere? I argue that clashes between ethnically distinct indigenous populations and migrants – i.e. ‘Sons of the Soil (SoS) conflict’ – erupt when there are large socio-economic and political horizontal inequalities between ‘dominant migrants’ and locals. A comparative case study of two Chinese minority regions based on ethnographic fieldwork and population data provides a vivid illustration of the mechanisms linking migration to SoS conflict. With fewer HIs between migrants and locals, Inner Mongolia avoided many of the violent clashes that were commonplace in Qinghai, a province fraught with disparities. 相似文献
605.
This paper reviews some of the theoretical and econometric issues involved in estimating growth models that include military spending. While the mainstream growth literature has not found military expenditure to be a significant determinant of growth, much of the defence economics literature has found significant effects. The paper argues that this is largely the product of the particular specification, the Feder–Ram model, that has been used in the defence economics literature but not in the mainstream literature. The paper critically evaluates this model, detailing its problems and limitations and suggests that it should be avoided. It also critically evaluates two alternative theoretical approaches, the Augmented Solow and the Barro models, suggesting that they provide a more promising avenue for future research. It concludes with some general comments about modelling the links between military expenditure and growth. 相似文献
606.
For a three‐sector Feder‐Ram framework, we present time‐series, cross‐sectional estimates for two cohorts, consisting of Asian and Latin American countries. The estimates indicate that private investment, and defense and non‐defense public spending are growth promoting for alternative error components representations. For the best error components representation, greater growth enhancement is associated with the two forms of public spending in Asia than in Latin America, while the opposite comparison characterizes private investment. Although defense is growth promoting, an opportunity cost exists insofar as non‐defense spending, financed by defense spending, appears to give a small net boost to growth in Latin America. 相似文献
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Mbekezeli C. Mkhize 《African Security Review》2013,22(2):190-206
This article assesses South Africa's 20 years of democracy, which has frequently been bedevilled by local protests. This article is particularly interested in those unrest incidents that have been distinct for one reason or another. In South Africa, the surge in local unrest incidents is often linked to police behaviour, which has become increasingly militant and brutal when quelling protests. While the right to protest is constitutional, the damage caused during protest action can be immense owing to acts of violence. Protestors' resorting to violent protest action is often linked to increased frustrations as a result of the government's inability to live up to the expectations of marginalised and poor communities. While this article draws primarily on existing scholarly debates focusing on social protests, the primary objective is to examine the impact of unrest incidents on local protests in post-apartheid South Africa. The article further argues that ‘spaces’ for participation in local governance should be created so that citizens can become architects of development and their own future. 相似文献
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The Secret War with Iran: The 30-Year Clandestine Struggle Against the World's Most Dangerous Terrorist Power, by Ronen Bergman. Free Press, 2008. 432 pages, $28 Fallout: The True Story of the CIA's Secret War on Nuclear Trafficking, by Catherine Collins and Douglas Frantz. Free Press, 2011. 304 pages, $26. The Twilight War: The Secret History of America's Thirty-Year War with Iran, by David Crist. Penguin Press, 2012. 638 pages, $36. Israel vs. Iran: The Shadow War, by Yaakov Katz and Yoaz Hendel. Potomac Books Inc., 2012. 254 pages, $30. Spies Against Armageddon: Inside Israel's Secret Wars, by Dan Raviv. Levant, 2012. 356 pages, $17. Confront and Conceal: Obama's Secret Wars and Surprising Use of American Power, by David E. Sanger. Crown Publishers, 2012. 476 pages, $28. 相似文献