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Modeling and simulation of electrical discharge machining
(2012)Procedia CIRP ~ 1st CIRP Global Web Conference: Interdisciplinary Research in Production Engineering (CIRPE 2012)Electrical discharge machining involves complex physical processes occurring simultaneously, which lead to the removal of material from both electrodes. During the discharge, material melts, evaporates and is ejected when the plasma channel collapses. Modeling the erosion process can help to better interpret and predict results, which are otherwise difficult to understand. In this work, the material removal rate is predicted based on the ...Conference Paper -
Two-planar graphs are quasiplanar
(2017)Leibniz International Proceedings in Informatics (LIPIcs) ~ 42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017)It is shown that every 2-planar graph is quasiplanar, that is, if a simple graph admits a drawing in the plane such that every edge is crossed at most twice, then it also admits a drawing in which no three edges pairwise cross. We further show that quasiplanarity is witnessed by a simple topological drawing, that is, any two edges cross at most once and adjacent edges do not cross.Conference Paper -
Optimal Freight Train Classification using Column Generation
(2012)OpenAccess Series in Informatics (OASIcs) ~ 12th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2012)We consider planning of freight train classification at hump yards using integer programming. The problem involves the formation of departing freight trains from arriving trains subject to scheduling and capacity constraints. To increase yard capacity, we allow the temporary storage of early freight cars on specific mixed-usage tracks. The problem has previously been modeled using a direct integer programming model, but this approach did ...Conference Paper -
Vertex Disjoint Paths for Dispatching in Railways
(2010)OpenAccess Series in Informatics (OASIcs) ~ 10th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2010)We study variants of the vertex disjoint paths problem in planar graphs where paths have to be selected from a given set of paths. We study the problem as a decision, maximization, and routing-in-rounds problem. Although all considered variants are NP-hard in planar graphs, restrictions on the location of the terminals, motivated by railway applications, lead to polynomially solvable cases for the decision and maximization versions of the ...Conference Paper -
Track Allocation in Freight-Train Classification with Mixed Tracks
(2011)OpenAccess Series in Informatics (OASIcs) ~ 11th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and SystemsWe consider the process of forming outbound trains from cars of inbound trains at rail-freight hump yards. Given the arrival and departure times as well as the composition of the trains, we study the problem of allocating classification tracks to outbound trains such that every outbound train can be built on a separate classification track. We observe that the core problem can be formulated as a special list coloring problem in interval ...Conference Paper -
Using spatial and spatial-extreme statistics to characterize snow avalanche cycles
(2011)Procedia Environmental Sciences ~ Spatial Statistics 2011: Mapping Global ChangeIn December 2008, an intense avalanche cycle occurred in the eastern part of the southern French Alps. Using this case study, this paper illustrates how spatial statistics can be used to analyse such abnormal temporal clusters of snow avalanches. Spatial regression methods are used to quantify aggregation and gradients and highlight the three day snowfall as the main explanatory factor. A max-stable model is developed to evaluate the ...Conference Paper -
Integration of process and solvent design towards a novel generation of CO2 absorption capture systems
(2011)Energy Procedia ~ 10th International Conference on Greenhouse Gas Control TechnologiesA method for the integrated process and solvent design of absorption separation systems is proposed in this work. The method is employed here to improve the energetic performance of a pre-combustion CO2 absorption capture process by simultaneous optimization of process and solvent variables. In the proposed design method, the discrete nature of solvent molecules is relaxed avoiding the introduction of integer variables in the solution of ...Conference Paper -
Collecting data on leisure travel
(2010)Procedia - Social and Behavioral SciencesConference Paper -
Congestion control in urban networks under saturated conditions via feedback gating
(2012)Procedia - Social and Behavioral SciencesConference Paper -