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Collaboration in tool development and capacity investments in high technology manufacturing networks

EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2008年第3期187卷 962-977页

作者： Dulluri, Sandeep Raghavan, N. R. Srinivasa Indian Inst Sci Dept Management Studies Bangalore 560012 Karnataka India

The procurement of capital intensive tools for hi-tech industries is one of the most complex tasks. Astronomical amounts of capital are invested in the processing equipment. Further, there is a large effort from the original equipment manufacturer (OEM) in customizing the high capital intensive equipment to suit their production process. This problem has received little attention from the quantitative decision making literature. For the first time we analyze the problem of OEM deciding on collaborating with the tool supplier via a special type of contract which we refer as "collaboration options". We show that there are benefits to both the OEM and the tool suppliers from the collaboration. We develop a two-stage strategic model for collaborative tool development and optimal capacity investment. In the first stage, we solve an optimal collaboration problem faced by the OEM. We formulate this problem as a discrete time stochastic stopping problem for a finite horizon. We use a policy iteration algorithm for deciding on optimal collaboration policy. In the second stage, we model the optimal investment decision of the OEM in tool development and capacity acquisition using real options theory. Unlike the traditional options literature, we consider the option value determined from the first stage model and decide on the optimal amount for investment. (C) 2006 Published by Elsevier B.V.

关键词： stochastic dynamic programming inverse real options optimal trajectory of investments volatility

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Simultaneous control of production, preventive and corrective maintenance rates of a failure-prone manufacturing system

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APPLIED NUMERICAL MATHEMATICS 2008年第2期58卷 180-194页

作者： Kenne, J. P. Nkeungoue, L. J. Univ Quebec Ecole Technol Super Dept Engn Mech Lab Prod Technol Integrat Montreal PQ H3C 1K3 Canada

This paper deals with the control of corrective and preventive maintenance rates in the production planning of a manufacturing system with machines subject to random failures and repairs. The introduction of preventive and corrective maintenance will increase the availability of the production system which guarantees the improvement of the system's productivity if the production planning is well done. The objective of this study is to minimize a discounted overall cost consisting of maintenance cost, inventory holding and backlog cost. The decision variables are the production, the machine preventive and repair rates which influence the inventory levels and the system capacity respectively. In the proposed model. the failure rate of a machine depends on its age;hence, the corrective and preventive maintenance policies are machine-age dependent. A computational algorithm, based on numerical methods, is used for solving the optimal control problem. Finally, a numerical example and a sensitive analysis are presented to illustrate the usefulness of the proposed approach. The structure of the optimal control policy is presented and extensions to more complex manufacturing systems are discussed. (c) 2006 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： corrective maintenance preventive maintenance production planning stochastic dynamic programming numerical methods

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Subpopulation triage: How to allocate conservation effort among populations

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CONSERVATION BIOLOGY 2008年第3期22卷 656-665页

作者： McDonald-Madden, Eve Baxter, Peter W. J. Possingham, Hugh P. Univ Queensland Sch Integrat Biol Appl Environm Decis Anal Ctr Ctr Ecol Brisbane Qld 4072 Australia Univ Canberra CRC Invas Anim Canberra ACT 2601 Australia

Threatened species often exist in a small number of isolated subpopulations. Given limitations on conservation spending, managers must choose from strategies that range from managing just one subpopulation and risking all other subpopulations to managing all subpopulations equally and poorly, thereby risking the loss of all subpopulations. We took an economic approach to this problem in an effort to discover a simple rule of thumb for optimally allocating conservation effort among subpopulations. This rule was derived by maximizing the expected number of extant subpopulations remaining given n subpopulations are actually managed. We also derived a spatiotemporally optimized strategy through stochastic dynamicprogramming. The rule of thumb suggested that more subpopulations should be managed if the budget increases or if the cost of reducing local extinction probabilities decreases. The rule performed well against the exact optimal strategy that was the result of the stochastic dynamic program and much better than other simple strategies (e.g., always manage one extant subpopulation or half of the remaining subpopulation). We applied our approach to the allocation offunds in 2 contrasting case studies: reduction of poaching of Sumatran tigers (Panthera tigris sumatrae) and habitat acquisition for San Joaquin kitfoxes (Vulpes macrotis mutica). For our estimated annual budget for Sumatran tiger management, the mean time to extinction was about 32 years. For our estimated annual management budget for kitfoxes in the San Joaquin Valley, the mean time to extinction was approximately 24 years. Our framework allows managers to deal with the important question of how to allocate scarce conservation resources among subpopulations of any threatened species.

关键词： decision theory financial resource allocation optimal management rule of thumb stochastic dynamic programming Sumatran tiger San Joaquin kit fox threatened species

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A finite horizon model for repairable systems with repair restrictions

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JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY 2008年第10期59卷 1321-1331页

作者： Lugtigheid, D. Jiang, X. Jardine, A. K. S. Univ Toronto Dept Mech & Ind Engn Toronto ON M5S 3G8 Canada Louisiana State Univ Baton Rouge LA 70803 USA

In this paper, we will present a new finite horizon repair/replacement decision model and derive the structure of the optimal policy for components that have a failure intensity that is a non-decreasing function of the number of times the component has been repaired, and independent of the component's age. Furthermore, the component has physical restrictions on the number of times it can be repaired, after which the only feasible decision is to replace the component. The fundamentals of this new decision model are based on the outcomes of several case studies done by the authors. Besides presenting the model and showing the structure of the optimal policy, the model will be applied to a real industry data set, and its results discussed.

关键词： repairable system maintenance optimization stochastic dynamic programming proportional hazards model

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Quantifying the effectiveness of VMI and integrated inventory management in a supply chain with uncertain lead-times and uncertain demands

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PRODUCTION PLANNING & CONTROL 2008年第6期19卷 590-600页

作者： Song, Dong-Ping Dinwoodie, John Univ Plymouth Sch Business Int Shipping & Logist Grp Plymouth PL4 8AA Devon England

This article considers the inventory management problem in a supply chain with uncertain replenishment lead-times and uncertain demands. The optimal integrated inventory management (IIM) policy is developed using stochastic dynamic programming theory. The IIM policy is contrasted with two pull-type vendor-managed inventory policies (VMI-1 and VMI-2) and a traditional retailer-managed inventory policy (RMI). Computational results show that in such stochastic supply chains, IIM performs about 23, 15, and 3% better than the optimised RMI, VMI-1 and VMI-2 policies, respectively, while two VMI policies are about 8 and 20% better than the best RMI. The basestock-based VMI-2 is a very good form of VMI. The ANOVA analysis reveals that the replenishment lead-times have the largest effect on the relative performance between IIM and other policies. Numerical examples demonstrated that the IIM policy has good structural properties and can be characterised by a set of switching curves.

关键词： inventory management supply chain uncertainty vendor-managed inventory stochastic dynamic programming

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Analysis of generation investment under different market designs

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IEEE TRANSACTIONS ON POWER SYSTEMS 2008年第3期23卷 859-867页

作者： Doorman, Gerard L. Botterud, Audun Norwegian Univ Sci & Technol Dept Elect Power Engn N-7493 Trondheim Norway Argonne Natl Lab Decis & Informat Sci Div CEEESA Argonne IL 60439 USA

In this paper a stochastic dynamic optimization model is used to analyze the effect of different market designs on generation investment and demand. The expansion decisions of profit-maximizing investors are simulated under four different market designs: energy only, capacity payment, capacity obligation, and capacity subscription. The results show that the overall social welfare is reduced compared to a centralized social welfare optimization for the first three policies. In particular, an energy only market with a low price cap leads to insufficient generation investments. Capacity payments and obligations give additional investment incentives and more generating capacity, but also result in a considerable transfer of wealth from consumers to producers due to the capacity payments. In contrast, the capacity subscription policy increases the social welfare, and both producers and consumers benefit. This is possible because capacity subscription explicitly utilizes differences in consumers' preferences for uninterrupted supply, This advantage must be weighed against the cost of implementation, which is not included in the model.

关键词： generation investment market design restructured power systems simulation stochastic dynamic programming

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Experimental or precautionary? Adaptive management over a range of time horizons

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JOURNAL OF APPLIED ECOLOGY 2008年第1期45卷 72-81页

作者： Hauser, Cindy E. Possingham, Hugh P. Univ Melbourne Sch Bot Australian Ctr Excellence Risk Anal Melbourne Vic 3010 Australia Univ Queensland Sch Integrat Biol Ctr Ecol St Lucia Qld 4072 Australia Univ Queensland Dept Math St Lucia Qld 4072 Australia

1. Many studies of adaptive harvest management already exist in the literature, but most (if not all) use long, sometimes infinite, time horizons. Such long-term objectives provide an opportunity to manage experimentally, so that poorly understood dynamics are learned and any returns sacrificed for experimentation are repaid by improved management over the remaining time horizon. 2. However, a manager is unlikely to weight outcomes in the distant future equally against outcomes in the present. Furthermore, the most appropriate model of system dynamics may not remain constant over the time-frame required to experiment, learn and improve management. In these cases the use of discounting and/or a finite time horizon fit the manager's assumptions and goals more effectively, and the value of experimentation is likely to be diminished. 3. In this paper we construct a simple model of a hypothetical population and compare optimal passive and active adaptive harvest strategies over a range of time horizons. This allows us to determine the optimal level of experimentation for short-, medium- and long-term goals. 4. We discover that the optimal active adaptive harvest strategy may be precautionary over short to medium time horizons, rather than experimental. That is, an action with known moderate benefits is preferred over an action with uncertain but marginally larger expected benefits. This runs counter to the widespread assumption in the adaptive management literature that incorporating learning into an optimization of management will encourage experimentation. 5. Synthesis and applications. The general results of this paper have potential application to any environmental management problem where adaptive management might be applied;for example, conservation, pest control, harvesting and management of water flows. We examine adaptive management over a range of finite time horizons to reflect a variety of possible management goals and assumptions. Our simple example demonstr

关键词： decision theory harvest optimization precautionary stochastic dynamic programming

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Preventive maintenance and upgrade system: Optimizing the whole performance system by components' replacement or rearrangement

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INTERNATIONAL JOURNAL OF PRODUCTION ECONOMICS 2008年第1期112卷 236-244页

作者： Rachaniotis, N. P. Pappis, C. P. Univ Piraeus Dept Ind Management Piraeus 18534 Greece

A decision-making model for reassembling different deteriorating subsystems and components of a complex system from used and new parts is proposed. The objective is to find the proper reassembly policies in a period of time so as to maximize the systems' overall performance values, under limited budget, and reassembly and compatibility constraints. Environmental gains are incurred from these policies, since the used components' life cycle, at least in some cases, is extended instead of ending by entering the waste stream. A stochastic dynamic programming approach is proposed, and an example in the case of personal computers is presented. (c) 2007 Elsevier B.V. All rights reserved.

关键词： reassembly benchmarking deteriorating components stochastic dynamic programming

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Optimal harvesting of stochastic spatial resources

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JOURNAL OF ENVIRONMENTAL ECONOMICS AND MANAGEMENT 2008年第1期56卷 1-18页

作者： Costello, Christopher Polasky, Stephen Donald Bren Sch Environm Sci & Management Dept Econ Santa Barbara CA 93117 USA Univ Minnesota Dept Appl Econ Minneapolis MN 55455 USA

We characterize the optimal harvest of a renewable resource in a generalized stochastic spatially explicit model. Despite the complexity of the model, we are able to obtain sharp analytical results. We find that the optimal harvest rule in general depends upon dispersal patterns of the resource across space, and only in special circumstances do we find a modified golden rule of growth that is independent of dispersal patterns. We also find that the optimal harvest rule may include closure of some areas to harvest, either on a temporary or permanent basis (biological reserves). Reserves alone cannot correct open access, but may, under sufficient spatial heterogeneity and connectivity, increase profits if appropriate harvest controls are in place outside of reserves. (C) 2008 Elsevier Inc. All rights reserved.

关键词： marine reserves spatial externalities stochastic dynamic programming renewable resources bioeconomic modeling

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Optimal management of molds in stored corn

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AGRICULTURAL SYSTEMS 2008年第3期98卷 220-227页

作者： Yigezu, Yigezu A. Alexander, Corinne E. Preckel, Paul V. Maier, D. E. Woloshuk, C. P. Mason, L. J. Lawrence, J. Moog, D. J. Purdue Univ Dept Agr Econ W Lafayette IN 47907 USA Kansas State Univ Dept Grain Sci & Ind Manhattan KS 66506 USA Purdue Univ Dept Bot & Plant Pathol W Lafayette IN 47907 USA Purdue Univ Dept Entomol W Lafayette IN USA Purdue Univ Dept Agr & Biol Engn W Lafayette IN 47907 USA

Long term storage of corn is becoming more common due to the recent increase in the demand for corn by ethanol plants. Infection of maize kernels by toxigenic fungi remains a challenging storage problem despite decades of research. Experts in storage management propose the use of a combination of preventive and monitoring-based responsive strategies in response to mold risks. In this paper, a stochastic dynamic programming model is solved to determine the expected profitability and optimal combination. timing, and intensity of the proposed mold management strategies using farmers' existing infrastructure. The results show that even with relatively high monitoring costs, maintaining high quality grain using a monitoring-based optimal mold management strategy costs less than the benefit it fetches. The current typical practice by Indiana farmers of aerating the grain until the end of December and doing nothing thereafter bears a high risk of economic losses if grain is to be stored until later during the summer. Generally, the optimal mold management strategy depends on monitoring the biophysical conditions of the grain and the time period under consideration. If the in-bin temperature is high and less than 5% of kernels are mold damaged, then aerating when the outside temperature is at least 3 degrees C less than the in-bin temperature and continuing to store the grain is the optimal strategy. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： Mold management Stored corn Expected profitability Integrated pest management Monitoring Aeration stochastic dynamic programming

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