7,977 research outputs found

    Spatial optimization for land use allocation: accounting for sustainability concerns

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    Land-use allocation has long been an important area of research in regional science. Land-use patterns are fundamental to the functions of the biosphere, creating interactions that have substantial impacts on the environment. The spatial arrangement of land uses therefore has implications for activity and travel within a region. Balancing development, economic growth, social interaction, and the protection of the natural environment is at the heart of long-term sustainability. Since land-use patterns are spatially explicit in nature, planning and management necessarily must integrate geographical information system and spatial optimization in meaningful ways if efficiency goals and objectives are to be achieved. This article reviews spatial optimization approaches that have been relied upon to support land-use planning. Characteristics of sustainable land use, particularly compactness, contiguity, and compatibility, are discussed and how spatial optimization techniques have addressed these characteristics are detailed. In particular, objectives and constraints in spatial optimization approaches are examined

    Conservation Payments under Risk: A Stochastic Dominance Approach

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    Conservation payments can be used to preserve forest and agroforest systems. To explain landowners’ land-use decisions and determine appropriate conservation payments, it is necessary to focus on revenue risk. Marginal conditional stochastic dominance rules are used to derive conditions for determining the conservation payments required to guarantee that the environmentally-preferred land use dominates. An empirical application to shaded-coffee protection in the biologically important Chocó region of West-Ecuador shows that conservation payments required for preserving shaded-coffee areas are much higher than those calculated under risk-neutral assumptions. Further, the extant distribution of land has strong impacts on the required payments.agroforest systems, conservation payments, land allocation, portfolio diversification, risk, stochastic dominance

    Dynamic Programming and Learning Models for Management of a Nonnative Species

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    Nonnative invasive species result in sizeable economic damages and expensive control costs. Because dynamic optimization models break down if controls depend in complex ways on past controls, non-uniform or scale-dependent spatial attributes, etc., decision support systems that allow learning may be preferred. We compare three models of an invasive weed in California’s grazing lands: (1) a stochastic dynamic programming model, (2) a reinforcement-based, experience-weighted attraction (EWA) learning model, and (3) an EWA model that also includes stochastic forage growth and penalties for repeated application of environmentally harmful control techniques. Results indicate that EWA learning models may be appropriate for invasive species management.Invasive weed species, optimal control, adaptive management

    Integrating bio-hubs in biomass supply chains: Insights from a systematic literature review

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    Biomass sources are geographically scattered, and seasonal changes influence their availability. Variations in location, type, and feedstock quality impose logistical and storage challenges. Such a dispersion and variety of biomass sources, as well as the dispersion of demand points, may undermine the economies of scale and increase the risk of supply shortage. By consolidating biomass preprocessing and distribution activities in bio-hub facilities, they can contribute to the overall resilience of biomass supply chains (BSCs) and ensure a more sustainable and cost-efficient approach to bioenergy production. As such, investigating the advantages and challenges associated with bio-hub implementation can offer invaluable insights on the efficiency and sustainability of BSCs. Despite its critical role, a major part of the literature on BSCs is confined to the decision-making processes related to biomass suppliers and bioconversion facilities. To bridge this research gap, the current study conducts a systematic literature review on bio-hub implementation within BSCs in the period of the last ten years. Shortlisted papers are classified and analyzed meticulously to extract possible improvements from BSC and modeling perspectives. From the BSC viewpoint, one notable gap is the little attention to mid-term and short-term decisions of bio-hub operations such as inventory control, resource management and production planning. Furthermore, the results revealed that environmental and social aspects of bio-hub implementation require considerable attention. From the modeling perspective, findings illustrate the underutilization of integrated approaches to incorporate micro-level and macro-level information in decision-making. In this regard, a number of areas are suggested for further exploration

    "Applying Optimization and the Analytic Hierarchy Process to Enhance Agricultural Preservation Strategies in the State of Delaware"

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    Using agricultural preservation priorities derived from an analytical hierarchy process by 23 experts from 18 agencies in the State of Delaware, this research uses weighted suitability attributes to evaluate the historical success of the State of Delaware’s agricultural protection fund, which spent nearly 100millioninitsfirstdecade.Thisresearchdemonstrateshowtheseoperationresearchtechniquescanbeusedonconcerttoaddressrelevantconservationquestions.Resultssuggestthatthestatessealedbidofferauction,whichdeterminestheyearlyconservationselections,issuperiortobenefittargetingapproachesfrequentlyemployedbyconservationorganizationsbutisinferiortotheoptimizationtechniqueofbinarylinearprogrammingthatcouldhaveprovidedadditionalbenefitstothestate,suchas12,000additionalacresworthanestimated100 million in its first decade. This research demonstrates how these operation research techniques can be used on concert to address relevant conservation questions. Results suggest that the state’s sealed-bid-offer auction, which determines the yearly conservation selections, is superior to benefit targeting approaches frequently employed by conservation organizations but is inferior to the optimization technique of binary linear programming that could have provided additional benefits to the state, such as 12,000 additional acres worth an estimated 25 million.Conservation Optimization, Farmland Protection, Analytic Hierarchy Process

    A Comprehensive Optimization Framework for Designing Sustainable Renewable Energy Production Systems

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    As the world has recognized the importance of diversifying its energy resource portfolio away from fossil resources and more towards renewable resources such as biomass, there arises a need for developing strategies which can design renewable sustainable value chains that can be scaled up efficiently and provide tangible net environmental benefits from energy utilization. The objective of this research is to develop and implement a novel decision-making framework for the optimal design of renewable energy systems. The proposed optimization framework is based on a distributed, systematic approach which is composed of different layers including systems-based strategic optimization, detailed mechanistic modeling and operational level optimization. In the strategic optimization the model is represented by equations which describe physical flows of materials across the system nodes and financial flows that result from the system design and material movements. Market uncertainty is also incorporated into the model through stochastic programming. The output of the model includes optimal design of production capacity of the plant for the planning horizon by maximizing the net present value (NPV). The second stage consists of three main steps including simulation of the process in the simulation software, identification of critical sources of uncertainties through global sensitivity analysis, and employing stochastic optimization methodologies to optimize the operating condition of the plant under uncertainty. To exemplify the efficacy of the proposed framework a hypothetical lignocellulosic biorefinery based on sugar conversion platform that converts biomass to value-added biofuels and biobased chemicals is utilized as a case study. Furthermore, alternative technology options and possible process integrations in each section of the plant are analysed by exploiting the advantages of process simulation and the novel hybrid optimization framework. In conjunction with the simulation and optimization studies, the proposed framework develops quantitative metrics to associate economic values with technical barriers. The outcome of this work is a new distributed decision support framework which is intended to help economic development agencies, as well as policy makers in the renewable energy enterprises

    Modeling water resources management at the basin level: review and future directions

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    Water quality / Water resources development / Agricultural production / River basin development / Mathematical models / Simulation models / Water allocation / Policy / Economic aspects / Hydrology / Reservoir operation / Groundwater management / Drainage / Conjunctive use / Surface water / GIS / Decision support systems / Optimization methods / Water supply

    Planning under risk and uncertainty

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    This thesis concentrates on the optimization of large-scale management policies under conditions of risk and uncertainty. In paper I, we address the problem of solving large-scale spatial and temporal natural resource management problems. To model these types of problems, the framework of graph-based Markov decision processes (GMDPs) can be used. Two algorithms for computation of high-quality management policies are presented: the first is based on approximate linear programming (ALP) and the second is based on mean-field approximation and approximate policy iteration (MF-API). The applicability and efficiency of the algorithms were demonstrated by their ability to compute near-optimal management policies for two large-scale management problems. It was concluded that the two algorithms compute policies of similar quality. However, the MF-API algorithm should be used when both the policy and the expected value of the computed policy are required, while the ALP algorithm may be preferred when only the policy is required. In paper II, a number of reinforcement learning algorithms are presented that can be used to compute management policies for GMDPs when the transition function can only be simulated because its explicit formulation is unknown. Studies of the efficiency of the algorithms for three management problems led us to conclude that some of these algorithms were able to compute near-optimal management policies. In paper III, we used the GMDP framework to optimize long-term forestry management policies under stochastic wind-damage events. The model was demonstrated by a case study of an estate consisting of 1,200 ha of forest land, divided into 623 stands. We concluded that managing the estate according to the risk of wind damage increased the expected net present value (NPV) of the whole estate only slightly, less than 2%, under different wind-risk assumptions. Most of the stands were managed in the same manner as when the risk of wind damage was not considered. However, the analysis rests on properties of the model that need to be refined before definite conclusions can be drawn

    MODELING SUSTAINABILITY IN RENEWABLE ENERGY SUPPLY CHAIN SYSTEMS

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    This dissertation aims at modeling sustainability of renewable fuel supply chain systems against emerging challenges. In particular, the dissertation focuses on the biofuel supply chain system design, and manages to develop advanced modeling framework and corresponding solution methods in tackling challenges in sustaining biofuel supply chain systems. These challenges include: (1) to integrate \u27environmental thinking\u27 into the long-term biofuel supply chain planning; (2) to adopt multimodal transportation to mitigate seasonality in biofuel supply chain operations; (3) to provide strategies in hedging against uncertainty from conversion technology; and (4) to develop methodologies in long-term sequential planning of the biofuel supply chain under uncertainties. All models are mixed integer programs, which also involves multi-objective programming method and two-stage/multistage stochastic programming methods. In particular for the long-term sequential planning under uncertainties, to reduce the computational challenges due to the exponential expansion of the scenario tree, I also developed efficient ND-Max method which is more efficient than CPLEX and Nested Decomposition method. Through result analysis of four independent studies, it is found that the proposed modeling frameworks can effectively improve the economic performance, enhance environmental benefits and reduce risks due to systems uncertainties for the biofuel supply chain systems
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