36,715 research outputs found

    REVENUE RISK AND FISHERY CHOICE WITH LINEAR-EXPONENTIAL UTILITY: AN APPLICATION TO BERING SEA/ALEUTIAN ISLANDS TRAWL FISHERIES

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    A discrete choice model of 1991-96 trawl groundfish fishery participation in the Bering Sea/Aleutian Islands region is developed and estimated. The model fits well, with strong risk and seasonal effects. Notably, the model uses routinely-collected data, suggesting this type of analysis can be a regular part of the management process.Resource /Energy Economics and Policy,

    Hierarchical Scheduling and Utility Disturbance Management in the Process Industry

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    This thesis deals with control of production at large-scale process industrial sites in the presence of disturbances. The main focus is on disturbances in the supply of utilities such as steam, cooling water and electricity. A general method for reducing the revenue loss due to disturbances in utilities is introduced, which may provide both proactive and reactive disturbance management strategies. Utility availability and area availability are introduced as performance indicators. These measures are used to obtain quick estimations of the revenue losses related to each utility. To obtain reactive strategies for utility disturbance management, a simple model of how utilities affect production in an area, and how utilities are shared between areas, is introduced. The modeling approach is utilized to formulate the production control problem at disturbances in utilities as an optimization problem. Measurement data are used to obtain empirical models of utility disturbances at an industrial site, which may be used as input to the optimization. Since production control closely relates to production scheduling, the integration of production scheduling based on orders and forecasts with production control at disturbances in utilities is studied in the final part of the thesis

    High impact activities in parks: best management practice and future research

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    Off-road driving, horseriding, rock climbing and similar activities can be lucrative for tour operators and important for local recreational groups, but contentious for management of national parks and protected areas, both because of safety and liability and because of potentially high environmental impacts. These include spreading weeds and pathogens, starting fires and crushing bird nests on beaches, amongst many others. In Australia as elsewhere, off-road vehicles and horses are allowed only in some places in some parks, and often only under permit. We have very little reliable scientific information to-date on just how serious these impacts may be, and on how well they might be managed through minimal-impact practices such as vehicle washdowns, stockfeed processing and seasonal closures. Such information can only be obtained through site specific ecological studies of the plants, animals and watercourses likely to be affected, differentiating tourism impacts from natural causes and fluctuations. This report examines management strategies for these activities worldwide and in Australia. Suggestions for best management practice and future research agendas are set

    Spatial economic aspects of the environment and environmental policy: New directions for research

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    This paper outlines major new research directions for research on spatial or interregional effects of the environment and envrionmental policy. It attempts to define and characterize key research questions that lie at the intersection of environmental and resource economics and regional and urban economics. This intersection is of considerable importance because at least some factors of production are mobile, both domestically and worldwide. In consequence, information concerning the value of environmental attributes is revealed when people and firms relocate. Additionally, environmental policy changes can alter the interregional or international distributions of factor incomes, population, and production of goods and services.

    Utility Disturbance Management in the Process Industry

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    Use of utilities, such as steam and cooling water, is very common at industrial sites. Utilities are often shared between several production areas, and a disturbance in the supply of a utility is therefore likely to affect a large part of the production site, and cause great loss of revenue. In order to minimize the loss of revenue due to disturbances in utilities, the optimal supply of utilities to different areas has to be determined. It is not evident how utility resources should be divided, as both buffer tank levels, the connections between areas and profitability of different areas must be considered. This thesis presents a general method for reducing the loss of revenue due to disturbances in utilities, the Utility Disturbance Management method (UDM). The method concerns identifying disturbances in utilities, estimating the loss of revenue due to such disturbances, and finding strategies for reducing the loss. A model of the production site is needed to complete all steps of the method. In this thesis, some modeling approaches are suggested, and on/off production modeling with and without buffer tanks is described in detail. The UDM method is applied to an industrial site at Perstorp using these two modeling approaches

    Reducing revenue loss due to disturbances in utilities using buffer tanks - A case study at Perstorp

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    Utilities, such as steam and cooling water, are often shared by several production areas at an industrial site. In order to minimize the loss of revenue due to disturbances in the supply of utilities, the optimal supply of utilities to different areas has to be determined. It is not evident how utility resources should be divided, as both buffer tank levels, the connections between areas, and the profitability of different products must be considered. This paper presents a case study at Perstorp, the objectives of which were to identify the utilities causing the greatest revenue losses at the site, and suggest strategies for reducing this loss using an on/off modeling approach including buffer tanks between areas

    A General Method for Handling Disturbances on Utilities in the Process Industry

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    Utilities, such as steam or cooling water, have shown to play an important role within the process industry, since a malfunctioning utility is a plant-wide disturbance that can lead to large revenue losses due to reduced production quantities. This work focuses on identifying disturbances on utilities that give economical consequences. Measures of utility availability and area availability are introduced and used for estimating the ratio of disturbances on utilities. A generic method for handling disturbances on utilities is presented, which could be applied using site models of different level of detail. Some modeling approaches for modeling a site are described and the framework of the general method is demonstrated with a case study example at Perstorp AB, Sweden

    Distributed photovoltaic systems: Utility interface issues and their present status. Intermediate/three-phase systems

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    The interface issues between the intermediate-size Power Conditioning Subsystem (PCS) and the utility are considered. A literature review yielded facts about the status of identified issues
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