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dynamic reserve site selection under contagion risk of deforestation

ECOLOGICAL MODELLING 2007年第1期201卷 75-81页

作者： Sabbadin, R. Spring, D. Rabier, C. -E. INRA de Toulouse Unité de Biométrie et Intelligence Artificielle BP 52627-31326 Castanet-Tolosan Cedex Castanet-Tolosan France Australian Centre for Biodiversity School of Biological Sciences PO Box 18 Monash University Clayton Vic. 3800 Australia

Recently, dynamic reserve site selection models based on stochastic dynamic programming (SDP) have been proposed. The models consider a random development pattern in which the probability that a site will be developed is independent of the development status of other sites. However, development often takes the form of a contagion process in which the sites most likely to be developed are near sites that already have been developed. To consider site selections in such cases, we propose improved algorithms that make use of a graph representation of the sites network. The first formulation is an exact, dynamic programming algorithm, with which theoretical and experimental complexities are evaluated. The exact method can be applied only to small problems (less than 10 sites), but real-world problems may have hundreds or thousands of sites, implying that heuristic selection methods must be used. We provide a general framework for describing such heuristic solution methods, and propose a new heuristic method based on a parameterised reinforcement learning algorithm. The method allows us to compute a heuristic function by performing and exploiting many simulations of the deforestation process. We show that the method can be applied to problems with hundreds of sites, and demonstrate experimentally that it outperforms previously proposed heuristic methods in terms of the average number of species conserved.

关键词： Contagion process Reinforcement learning Reserve selection stochastic dynamic programming Uncertainty

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Mining and modeling for a metropolitan Atlanta ozone pollution decision-making framework

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IIE TRANSACTIONS 2007年第6期39卷 607-615页

作者： Yang, Zehua Chen, Victoria C. P. Chang, Michael E. Murphy, Terrence E. Tsai, Julia C. C. Univ Texas Dept Ind & Mfg Syst Engn Arlington TX 76019 USA Abbott Labs Irving TX 75038 USA Georgia Inst Technol Sch Earth & Atmospher Sci Atlanta GA 30332 USA Joy You Ind Corp Chicago IL 60610 USA

In this paper, we present a Decision-Making Framework (DMF) for reducing ozone pollution in the metropolitan Atlanta region. High ground-level concentrations of ozone continue to be a serious problem in several US cities, and Atlanta is one of the most serious of these cases. In contrast to the "trial and error" approach utilized by state government decision-makers, our DMF searches for dynamic and focused control strategies that require a lower total reduction of emissions than current control strategies. Our DMF utilizes a rigorous stochastic dynamic programming formulation and includes an Atmospheric Chemistry Module to represent how ozone concentrations change over time. This paper focuses on the procedures within the Atmospheric Chemistry Module. Using the US EPA's Urban Airshed Model for Atlanta, we use mining and metamodeling tools to develop a computationally efficient representation of the relevant ozone air chemistry. The proposed approach is able to effectively model changes in ozone concentrations over a 24-hour period.

关键词： data mining metamodeling decision-making ozone pollution stochastic dynamic programming urban airshed model

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A new approach to modelling, control and simulation of knowledgeable manufacturing cell

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2007年第17期45卷 3779-3808页

作者： Yan, H. S. Dong, H. Southeast Univ Res Inst Automat Nanjing 210096 Peoples R China

The running of the knowledgeable manufacturing cell (KMC) is a typical discrete event dynamic process. Methods used to model and analyse discrete event dynamic systems (DEDS) include Petri net and automata theory. In this paper, a new matrix-automaton is proposed to model the KMC and solve the task control problems existing in the KMC. The automaton is of structured property and can be used to analyse the dynamic performance of the KMC. stochastic dynamic programming is used to derive the optimal task control strategy of the automaton, and a simulation method and program are proposed to simulate the running of the KMC. The matrix-automaton model of an experimental KMC including m manufacturing agents and n classes of workpieces is built and solved by the methods in this paper. Compared with the random control principle, the objective function value of the control strategy in this paper is obviously lower, which testifies the validity and feasibility of the control strategy.

关键词： knowledgeable manufacturing cell matrix-automaton stochastic dynamic programming control strategy simulation

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An alternative approach to the operation of multinational reservoir systems:: Application to the Amistad & Falcon system (Lower Rio Grande Rio Bravo)

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WATER RESOURCES MANAGEMENT 2007年第4期21卷 677-698页

作者： Serrat-Capdevila, Aleix Valdes, Juan B. Univ Arizona Dept Hydrol & Water Resources Tucson AZ 85721 USA Univ Arizona SAHRA Sustainabil Semiarid Hydrol & Riparian Area Tucson AZ 85721 USA Univ Arizona Dept Civil Engn & Engn Mech Tucson AZ 85721 USA

An optimization approach for the operation of international multi-reservoir systems is presented. The approach uses stochastic dynamic programming (SDP) algorithms - both steady-state and real-time - to develop two models. In the first model, the reservoirs and flows of the system are aggregated to yield an equivalent reservoir, and the obtained operating policies are disaggregated using a non-linear optimization procedure for each reservoir and for each nation's water balance. In the second model a multi-reservoir approach is applied, disaggregating the releases for each country's water share in each reservoir. The non-linear disaggregation algorithm uses SDP-derived operating policies as boundary conditions for a local time-step optimization. Finally, the performance of the different approaches and methods is compared. These models are applied to the Amistad-Falcon International Reservoir System as part of a binational dynamic modeling effort to develop a decision support system tool for a better management of the water resources in the Lower Rio Grande Basin, currently enduring a severe drought.

关键词： stochastic dynamic programming multinational reservoir systems multi-reservoir modeling approach country water budgets quantitative model comparison

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Neuro-dynamic programming for designing water reservoir network management policies

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CONTROL ENGINEERING PRACTICE 2007年第8期15卷 1031-1038页

作者： Castelletti, A. de Rigo, D. Rizzoli, A. E. Soncini-Sessa, R. Weber, E. Politecn Milan Dipartimento Elettron & Informat I-20133 Milan Italy IDSIA CH-6928 Manno Lugano Switzerland

stochastic dynamic programming (SDP) can improve the management of a multipurpose water reservoir by generating management policies which are efficient with respect to the management objectives (flood protection, water supply for irrigation, hydropower generation, etc.). The improvement in efficiency is even more remarkable for networks of reservoirs. Unfortunately, SDP is affected by the well-known 'curse of dimensionality', i.e. computational time and computer memory occupation increase exponentially with the dimension of the problem (number of reservoirs), and the problem rapidly becomes intractable. Neuro-dynamic programming (NDP) can sensibly mitigate this limitation by approximating Bellman functions with artificial neural networks (ANNs). In this paper the application of NDP to the problem of the management of reservoir networks is introduced. Results obtained in a real-world case study are finally presented. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： water reservoir network reservoir management stochastic dynamic programming neuro-dynamic programming

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Supply chain operations in the presence of a spot market:: a review with discussion

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JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY 2007年第11期58卷 1412-1429页

作者： Haksoz, C. Seshadri, S. City Univ London CASS Business Sch Fac Management London EC1Y 8TZ England NYU New York NY USA

We survey the recent literature on the use of spot market operations to manage procurement in supply chains. We present results in two categories: work that deals with optimal procurement strategies and work related to the valuation of procurement contracts. As an example of the latter, we provide new results on valuation of a supply contract with abandonment option. Based on our review, we also discuss the scope for doing further work.

关键词： supply chain contracts stochastic dynamic programming risk real options practice of OR

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Take a risk: Preferring prevention over control of biological invaders

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ECOLOGICAL ECONOMICS 2007年第2期62卷 216-222页

作者： Finnoff, David Shogren, Jason F. Leung, Brian Lodge, David Univ Wyoming Dept Econ & Finance Dept 3985 Laramie WY 82071 USA McGill Univ Dept Biol Montreal PQ H3A 1B1 Canada McGill Univ Sch Environm Montreal PQ H3A 1B1 Canada Univ Notre Dame Dept Biol Sci Notre Dame IN 46556 USA

Scientists have argued that invasive species can be managed most cost effectively with greater investments in prevention. Further, under ideas like the precautionary principle it is reasonable to expect that a cautious manager would use more prevention relative to control because it keeps more invaders out. Yet, this is not typically done. In many cases, private and public resources are invested primarily to control existing invaders rather than to prevent new invasions. Managers frequently wait until after invaders have arrived and then scramble to limit the damages. We believe these paradoxical decisions can be understood by recognizing the link between typical human preferences for risk bearing and the technology of risk reduction. We demonstrate quantitatively how managers perceived to be cautious or averse to risk tend to shy away from prevention relative to control. This counterintuitive result arises because control is a safer choice than prevention because its productivity is relatively less risky: it works to remove existing invaders from the system. In contrast, the productivity of prevention is more uncertain because prevention only reduces the chance of invasion, it does not eliminate it, and invasion may not occur even in the absence of prevention. Managers' averse to risk will inherently avoid as much uncertainty as possible, whether the source of uncertainty regards ecological outcomes or economic productivity. implications for environmental decision making are clear. In invasive species management, if managers act as though they are risk averse, their caution can backfire when it leads to more control rather than prevention. The social consequences of this choice are a greater probability of future invasions and lower social welfare. Our results suggest that social welfare is highest when managers were willing to "take a risk" with prevention. (c) 2006 Elsevier B.V. All rights reserved.

关键词： biological invasions risk preferences stochastic dynamic programming

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Accounting for habitat loss rates in sequential reserve selection: Simple methods for large problems

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BIOLOGICAL CONSERVATION 2007年第3期136卷 470-482页

作者： Moilanen, Atte Cabeza, Mar Univ Helsinki Dept Biol & Environm Sci Metapopulat Res Grp FIN-00014 Helsinki Finland

We develop reserve selection methods for maximizing either species retention in the landscape or species representation in reserve areas. These methods are developed in the context of sequential reserve selection, where site acquisition is done over a number of years, yearly budgets are limited and habitat loss may cause some sites to become unavailable during the planning period. The main methodological development of this study is what we call a site-ordering algorithm, which maximizes representation within selected sites at the end of the planning period, while accounting for habitat loss rates in optimization. Like stochastic dynamic programming, which is an approach that guarantees a globally optimal solution, the ordering algorithm generates a sequence in which sites are ideally acquired. As a distinction from stochastic dynamic programming, the ordering is generated via a relatively fast approximate process, which involves hierarchic application of the principle of maximization of marginal gain. In our comparisons, the ordering algorithm emerges a clear winner, it does well in terms of retention and is superior to simple heuristics in terms of representation within reserves. Unlike stochastic dynamic programming, the ordering algorithm is applicable to relatively large problem sizes, with reasonable computation times expected for problems involving thousands of sites. (C) 2007 Elsevier Ltd. All rights reserved.

关键词： site selection representation retention site ordering algorithm optimization stochastic dynamic programming

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Energetic state and the performance of dawn chorus in silvereyes (Zosterops lateralis)

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BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY 2007年第4期61卷 579-587页

作者： Barnett, Craig A. Briskie, James V. Univ Canterbury Sch Biol Sci Christchurch New Zealand

stochastic dynamic programming (SDP) models predict that males singing to attract a mate should concentrate singing in what has been termed the dawn chorus. This is because male birds should have a variable surplus of fat in the morning that can be used to fuel singing, with the amount of fat available dependent upon such factors as his quality, foraging success and risk of predation. In this manner, the dawn chorus can act as an indicator of male quality in the context of female mate choice. We test a key prediction of SDP models of singing behaviour that males with greater fat levels should sing more. We conducted an experiment where we recorded the dawn chorus of male silvereyes (Zosterops lateralis) on three consecutive days. Each male received supplementary food on the second day, which enabled us to sample his dawn chorus before, during and after food supplementation. We also collected data on the effect of supplementary food on the body mass of silvereyes. As predicted by SDP models, we found that silvereyes sang for a greater proportion of the time after receiving supplementary food. Supplementary food also had a significant effect on the complexity of a male song, indicating that males not only increased the quantity of their song but also the quality of their song when they received extra food. As the provision of supplementary food significantly increased the mass of fed birds, our results support a causal link between male energy reserves and his ability to perform the dawn chorus.

关键词： dawn chorus mate quality stochastic dynamic programming songbirds

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The optimal dynamic allocation of conservation funds under financial uncertainty

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ECOLOGICAL ECONOMICS 2007年第2-3期61卷 255-266页

作者： Drechsler, Martin Waetzold, Frank UFZ Helmholtz Ctr Environm Res Dept Ecol Modelling D-04318 Leipzig Germany UFZ Helmholtz Ctr Environm Res Dept Econ D-04318 Leipzig Germany

This paper analyses a situation where the survival of an endangered species depends on certain types of conservation measures being carried out regularly, yet there is financial uncertainty in the future periodical availability of a budget to finance the conservation measures. One option to insure against future budget uncertainty is to save money. To maximise the long-term survival of the endangered species, it has to be decided in each period whether to spend the available money now or to allocate it to future use. The paper provides an ecological-economic model for this stochastic dynamic optimisation problem. The findings include that the available money should be allocated as evenly as possible among periods, which may require some precautionary saving in early periods to take uncertainty into account. Under certain conditions, however, increasing uncertainty may at least temporarily increase the optimal payment. Among other parameters, the amount of precautionary actions depends on the magnitude of natural variation in the species population. (c) 2006 Elsevier B.V. All rights reserved.

关键词： biodiversity conservation ecological-economic modelling stochastic dynamic programming uncertainty precautionary saving

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