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
No abstract has been registered
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.
Authors
Ermias Deribe Bjørn Olav Rosseland Reidar Borgstrøm Brit Salbu Zinabu Gebremariam Elias Dadebo Lindis Skipperud Ole Martin EkloAbstract
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Authors
Thiago de Castro Vitalis Wekesa Rafael de Andrade Moral Borges Demetrio Italo Jr Delalibera Ingeborg KlingenAbstract
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Authors
Gayaneh Kyureghian Rodolfo M. Jr. NaygaAbstract
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Authors
Georgia S. Papoutsi Andreas C. Drichoutis Rodolfo M. Jr. NaygaAbstract
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Abstract
We provide a demonstration of the new tomographic profiling (TP) technique, here applied to forestry for the first time. The portable ground-based synthetic aperture radar (GB-SAR) system was used to capture profiles of the vertical polarimetric backscattering patterns through a 7 m tall stand of Norway spruce trees. The TP scheme collects data as for normal SAR imaging, but with the antennae aligned in the along-track direction. Adaptive post-processing meant that each TP scan simultaneously captured along-track image transects over the incidence angle range 0°–60°. An important feature of the derived image products is that incidence angle is constant at every point within an image. The measured HH–VV height backscatter profiles were very similar, whilst the cross-/co-polarization ratio showed very little variation with height through the stand. Backscattering profiles showed closest agreement with the branch biomass distribution through the canopy, rather than with trunk or branch + trunk biomasses. Equivalent interferometric tree heights were estimated from the centre of mass of the backscatter-height distribution, which displayed increasing height with increasing incidence angle. There was no significant vertical separation between the cross- and co-polarization returns.
Abstract
No abstract has been registered