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Optimizing the selection of resources to accomplish a set of tasks involves evaluating the tradeoffs between the cost of maintaining the resources necessary to accomplish the tasks and the penalty cost associated with unfinished tasks. We consider the case where resources are categorized into types, and limits (capacity) are imposed on the number of each type that can be selected. The objective is to minimize the sum of penalty costs and resource costs. This problem has several practical applications including production planning, new product design, menu selection and inventory management. We develop a branch‐and‐bound algorithm to find exact solutions to the problem. To generate bounds, we utilize a dual ascent procedure which exploits the special structure of the problem. Information from the dual and recovered primal solutions are used to select branching variables. We generate strong valid inequalities and use them to fix other variables at each branching step. Results of tests performed on reasonably sized problems are presented. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 19–37, 1999 相似文献
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H. T. Papadopoulos 《海军后勤学研究》1998,45(7):669-685
This paper uses the holding time model (HTM) method to derive an approximate analytic formula for the calculation of the mean throughput of a K-station production line with no buffers between any two successive stations. Service times follow the two-stage Coxian (C2) distribution at all stations. The paper provides a formula that relates the third moment of the service completion (or virtual service) time with the respective parameters of the service time, the repair time and the time to breakdown (the latter is assumed to follow the exponential distribution). In this way, it concludes that under certain conditions the two-stage Coxian distribution can be used to approximate any general distribution matching the first three moments of the service completion time distribution. The mean holding times (consisting of the service and blocking periods) of all stations of the line are obtained in an analytical form. Numerical results are provided for the mean throughput of lines with up to 20 stations. These results are shown to have a good accuracy compared against results obtained from the Markovian state method (for short lines) and results from simulation (for longer lines). © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 669–685, 1998 相似文献
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Motivated by challenges in the smartphone manufacturing industry, we develop a dynamic production ramp-up model that can be applied to economically satisfy nonstationary demand for short-life-cycle products by high-tech companies. Due to shorter life cycles and more rapid evolution of smartphones, production ramp-up has been increasingly critical to the success of a new smartphone. In the production ramp-up, the key challenge is to match the increasing capacity to nonstationary demand. The high-tech smartphone manufacturers are urged to jointly consider the effect of increasing capacity and decreasing demand. We study the production planning problem using a high-dimensional Markov decision process (MDP) model to characterize the production ramp-up. To address the curse of dimensionality, we refine Monte Carlo tree search (MCTS) algorithm and theoretically analyze its convergence and computational complexity. In a real case study, we find that the MDP model achieves revenue improvement by stopping producing the existing product earlier than the benchmark policy. In synthetic instances, we validate that the proposed MCTS algorithm saves computation time without loss of solution quality compared with traditional value iteration algorithm. As part of the Lenovo production solution, our MDP model enables high-tech smartphone manufacturers to better plan the production ramp-up. 相似文献
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Jordi Molas‐Gallart 《Defence and Peace Economics》2013,24(2):141-158
It is often stated that technological change in the military field is characterised by the introduction of radical innovations rather than by incremental processes of technological change. This article illustrates the diversity of military innovation by arguing that technological change in missiles systems is dominated by incremental change. While some large weapons platforms display the design rigidities normally associated with complex systems, missiles are characterised by “flexible modularity”. Flexible modularity facilitates the continuous introduction of upgrades, and makes missile systems amenable to gradual technological change. Besides, it has significant implications for the future role of missile systems, and poses special problems for missile disarmament and technology control initiatives. 相似文献
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Miodrag Ivanovic 《Defence and Peace Economics》2013,24(3):253-270
This survey article focuses on defence economics issues and provides data and analysis on the Federal Republic of Yugoslavia's (FRY) defence policy, defence spending, the size of its armed forces, its defence industries and the cost of the civil war. The main section is devoted to the period from 1990 to the present and deals with the following aspects: the situation after the break‐up of the former Yugoslavia, general economic data; the cost of the civil war, the defence budget; the armed forces; the manufacture of armaments and the structure of the defence industry. 相似文献
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This study analyses the performance of the productivity of the main industrial subsectors composing the security and defence technological and industrial base (SDTIB) in Spain from 1996 to 2009. Accordingly, we have used the non-parametric data envelopment analysis and bootstrapping techniques to compute Malmquist productivity indexes that allow us to split productivity growth into efficiency change and technical progress. The results obtained show productivity improvement in the SDTIB as a whole due mainly to advances in technology and to a lesser extent to the contribution of technical efficiency. The bootstrap approach yields further evidence, as for many cases, productivity growth or decline, is not statistically significant. This is the first time a study of this kind has been carried out on the production process of this sector in Spain. 相似文献
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梁春 《中国人民武装警察部队学院学报》2014,30(12):36-38
根据汽车生产厂房的特点,分别从厂房的火灾危险性确定、耐火等级确定、厂房的防火分区、人员疏散距离、厂房的灭火系统设置、厂房的消防给水、涂装车间消防水枪出口等方面论述了汽车生产厂房与现行《建筑设计防火规范》规定不符合的内容,并提出了建议。 相似文献
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Complexity and workload considerations in product mix decisions under the theory of constraints 下载免费PDF全文
The literature on the product mix decision (or master production scheduling) under the Theory of Constraints (TOC), which was developed in the past two decades, has addressed this problem as a static operational decision. Consequently, the developed solution techniques do not consider the system's dynamism and the associated challenges arising from the complexity of operations during the implementation of master production schedules. This paper aims to address this gap by developing a new heuristic approach for master production scheduling under the TOC philosophy that considers the main operational factors that influence actual throughput after implementation of the detailed schedule. We examine the validity of the proposed heuristic by comparison to Integer Linear Programming and two heuristics in a wide range of scenarios using simulation modelling. Statistical analyses indicate that the new algorithm leads to significantly enhanced performance during implementation for problems with setup times. The findings show that the bottleneck identification approach in current methods in the TOC literature is not effective and accurate for complex operations in real‐world job shop systems. This study contributes to the literature on master production scheduling and product mix decisions by enhancing the likelihood of achieving anticipated throughput during the implementation of the detailed schedule. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 357–369, 2015 相似文献