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81.
In this paper, a single‐machine scheduling problem with weighted earliness and tardiness penalties is considered. Idle time between two adjacent jobs is permitted and due dates of jobs could be unequal. The dominance rules are utilized to develop a relationship matrix, which allows a branch‐and‐bound algorithm to eliminate a high percentage of infeasible solutions. After combining this matrix with a branching strategy, a procedure to solve the problem is proposed. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 760–780, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10039 相似文献
82.
This paper studies a scheduling problem arising in a beef distribution system where pallets of various types of beef products in the warehouse are first depalletized and then individual cases are loaded via conveyors to the trucks which deliver beef products to various customers. Given each customer's demand for each type of beef, the problem is to find a depalletizing and truck loading schedule that fills all the demands at a minimum total cost. We first show that the general problem where there are multiple trucks and each truck covers multiple customers is strongly NP‐hard. Then we propose polynomial‐time algorithms for the case where there are multiple trucks, each covering only one customer, and the case where there is only one truck covering multiple customers. We also develop an optimal dynamic programming algorithm and a heuristic for solving the general problem. By comparing to the optimal solutions generated by the dynamic programming algorithm, the heuristic is shown to be capable of generating near optimal solutions quickly. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003 相似文献
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MacGregor and Harris (J Quality Technol 25 (1993) 106–118) proposed the exponentially weighted mean squared deviation (EWMS) and the exponentially weighted moving variance (EWMV) charts as ways of monitoring process variability. These two charts are particularly useful for individual observations where no estimate of variability is available from replicates. However, the control charts derived by using the approximate distributions of the EWMS and EWMV statistics are difficult to interpret in terms of the average run length (ARL). Furthermore, both control charting schemes are biased procedures. In this article, we propose two new control charts by applying a normal approximation to the distributions of the logarithms of the weighted sum of chi squared random variables, which are respectively functions of the EWMS and EWMV statistics. These new control charts are easy to interpret in terms of the ARL. On the basis of the simulation studies, we demonstrate that the proposed charts are superior to the EWMS and EWMV charts and they both are nearly unbiased for the commonly used smoothing constants. We also compare the performance of the proposed charts with that of the change point (CP) CUSUM chart of Acosta‐Mejia (1995). The design of the proposed control charts is discussed. An example is also given to illustrate the applicability of the proposed control charts. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009 相似文献
84.
We consider a processing network in which jobs arrive at a fork‐node according to a renewal process. Each job requires the completion of m tasks, which are instantaneously assigned by the fork‐node to m task‐processing nodes that operate like G/M/1 queueing stations. The job is completed when all of its m tasks are finished. The sojourn time (or response time) of a job in this G/M/1 fork‐join network is the total time it takes to complete the m tasks. Our main result is a closed‐form approximation of the sojourn‐time distribution of a job that arrives in equilibrium. This is obtained by the use of bounds, properties of D/M/1 and M/M/1 fork‐join networks, and exploratory simulations. Statistical tests show that our approximation distributions are good fits for the sojourn‐time distributions obtained from simulations. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008 相似文献
85.
Since a system and its components usually deteriorate with age, preventive maintenance (PM) is often performed to restore or keep the function of a system in a good state. Furthermore, PM is capable of improving the health condition of the system and thus prolongs its effective age. There has been a vast amount of research to find optimal PM policies for deteriorating repairable systems. However, such decisions involve numerous uncertainties and the analyses are typically difficult to perform because of the scarcity of data. It is therefore important to make use of all information in an efficient way. In this article, a Bayesian decision model is developed to determine the optimal number of PM actions for systems which are maintained according to a periodic PM policy. A non‐homogeneous Poisson process with a power law failure intensity is used to describe the deteriorating behavior of the repairable system. It is assumed that the status of the system after a PM is somewhere between as good as new for a perfect repair and as good as old for a minimal repair, and for failures between two preventive maintenances, the system undergoes minimal repairs. Finally, a numerical example is given and the results of the proposed approach are discussed after performing sensitivity analysis. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2008 相似文献
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Edward Katumba‐Wamala 《Small Wars & Insurgencies》2013,24(3):160-171
Africa has had no shortage of guerrilla movements since 1975. However, very few have been successful that have not fought against European colonial rule or white minority regimes. Fundamentally, without external support, these movements have been almost universally failures. One major exception to this rule was the National Resistance Army of Uganda, which overthrew the regime led by General Tito Okello in 1986. What made the National Resistance Army a success and distinct from other guerrilla armies were its sound leadership, its superior organization and its creative strategy. 相似文献
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David A. Charters Sam C. Sarkesian Daniel W. Fitz‐Simons 《Small Wars & Insurgencies》2013,24(2):280-286
A. Hamish Ion and E.J. Errington (eds.), Great Powers and Little Wars: the Limits of Power. Westport, CT: Praeger, 1993. Pp.246, select biblio, index. $49.95. ISBN 0275–93965–0 John M. Rothgeb, Jr., Defining Power: Influence and Force in the Contemporary International System. New York: St. Martin's Press, 1993. Pp.205. $39.95 (hbk); $18.70 (pbk). ISBN 0312–086–822 and 061–056 Brian L. Job (ed.), The Insecurity Dilemma: National Security in Third World States. Boulder, CO: Lynne Rienner Publishers, 1992, Pp.257. $37. ISBN 1–55587–267–0 Edwin G. Corr and Stephen Sloan (eds.), Low‐Intensity Conflict: Old Threats in a New World. Westview Studies in Regional Security, Boulder, CO: Westview, 1992. Pp.310, maps, figures, index. $55 (hbk); $18.85 (pbk). ISBN 0–8133–8593–8 and 8594–6 相似文献
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Uri Bar‐Joseph 《战略研究杂志》2013,36(3):46-66
According to common wisdom, the Golan provides Israel with an ideal platform for its warning stations as well as the best available defense line against a massive Syrian ground attack. Challenging this belief, this article compares the present situation with an alternative defined by (a) a complete Israeli withdrawal from the Golan, (b) a complete demilitarization of the evacuated territory, and (c) considerable limitations on Syrian military presence in the area between the Golan and Damascus. The article reaches two conclusions. First, that a combination of means, primarily airborne and space‐based platforms, can effectively answer Israel's northern intelligence needs. Second, the security arrangements set above, combined with recent revolutionary military technologies and its relative advantage in this domain, offer Israel an effective ‐ in some respects even a better ‐ alternative, to the present defense line. 相似文献
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