Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2013
Abstract
The ground-based harvesting system consisting of a harvester and a forwarder is the dominant harvesting system in parts of the world, due to its high productivity. Both machines usually operate along extraction trails, and are equipped with cranes that can reach some distance from the extraction trail. In this work we optimize the layout of an extraction trail network by considering how terrain topography influences the cost of forwarding. Given the complexity of finding optimal machine trails for terrain transportation, traditional optimization methods might be limited due to the problem size. In this study, the optimization is done with a greedy constructive heuristic and a Greedy Randomized Adaptive Search Procedure (GRASP) metaheuristic, and the results of the two solution techniques are compared. Both the greedy heuristic and the GRASP metaheuristic were examined for a semi-random terrain and a smooth cone-shaped terrain, and provided useable extraction trail layouts in terms of how a forest machine operates on slopes. The objective value of the solution found by the GRASP metaheuristic was 5.6% better than the greedy heuristic in the semi-random terrain, and 2.3% better in the cone-shaped terrain. The result of this study showed that the GRASP metaheuristic is useful for finding feasible routes in the terrain, increasing efficiency. The method could be useful for planning feasible routes in the terrain, thereby increasing efficiency, or for acquiring a better estimate of the cost of terrain transport in price setting.
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Authors
Bruce Talbot Morten NittebergAbstract
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Helge BerglannAbstract
This paper shows that a simple scheme of non-linear taxes coupled with tradable pollution permits can secure the .rst best outcome even in absence of information about abatement costs. Evidence of the existence of a Pareto optimal Nash equilibrium is given. Di¤erential system theory and stochastic approximation are used to prove that the outcome is globally and locally stable. Equilibrium is reached after repeated play. At each round agents make myopic steps and form local approximations, restricting their attention to one variable at any stage. The same procedure also applies also when stochastic elements are involved.
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Siv SkarAbstract
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Theo RuissenAbstract
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Theo RuissenAbstract
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Stefanos Xenarios Paul PavelicAbstract
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Fuad Gasi Mirsad Kurtovic Belma Kalamujic Naris Pojskic Jasmin Grahic Clive Kaiser Mekjell MelandAbstract
No abstract has been registered