[Show abstract][Hide abstract] ABSTRACT: The Region Connection Calculus based on 8 relations (RCC8) is one of several extensively researched methods to use for qualitative spatial representation and reasoning. We discuss several issues arising when representing RCC8 in OWL DL, a decidable fragment of OWL. There is no direct encoding of such a calculus in OWL DL, as the language lacks required features such as role reflexivity, role Boolean operators, and role inclusion axioms. Some of these features are to be included in the new version of the OWL standard, OWL 2, but this language still lacks the expressive power to support role negations, conjunctions, disjunctions, and complex role inclusion axioms. Recently, advances in description logics languages as SROIQBs have made possible expressing some of the above constructs, while maintaining the decidability of the language. In this paper, we exploit these new opportunities by providing qualitative spatial knowledge representation on the Semantic Web.
[Show abstract][Hide abstract] ABSTRACT: Container stacking rules are an important factor in container terminal efficiency. In this paper, we investigate two concepts
to increase efficiency and compare them to several benchmark algorithms, using a discrete-event simulation tool. The first
concept is to use knowledge about container departure times, in order to limit the number of reshuffles. We stack containers
leaving shortly before each other on top of each other. The second concept is the trade-off between stacking further away
in the terminal versus stacking close to the exit points and accepting more reshuffles. It is concluded that even the use
of imperfect or imprecise departure time information leads to significant improvements in efficiency. Minimizing the difference
in departure times proved to be important. It was also found that the trade-off between stacking further away in the terminal
versus stacking close by the exit points and accepting more reshuffles leads to improvements over the benchmark.
KeywordsContainer stacking-Marine terminals-Simulation-Container rehandling
[Show abstract][Hide abstract] ABSTRACT: Container stacking rules are an important factor in container terminal efficiency. In this paper, we describe a discrete-event simulation model that has been used to evaluate online container stacking rules. We build on prior research and demonstrate that results obtained for smaller stacking areas are also valid for a larger stacking area. The use of information regarding container departure times (even if is imperfect) is shown to be more beneficial than the use of exchange categories. Stacking rules that take the workload of the automated stacking cranes into account outperform rules that do not. The experiments conducted with the simulation model show that it can capture the amount of detail required and that it is flexible enough to support the evaluation of the stacking rules.