TY - JOUR A1 - Koster, Arie A1 - Scheidweiler, Robert A1 - Tieves, Martin T1 - A flow based pruning scheme for enumerative equitable coloring algorithms JF - A flow based pruning scheme for enumerative equitable coloring algorithms N2 - An equitable graph coloring is a proper vertex coloring of a graph G where the sizes of the color classes differ by at most one. The equitable chromatic number is the smallest number k such that G admits such equitable k-coloring. We focus on enumerative algorithms for the computation of the equitable coloring number and propose a general scheme to derive pruning rules for them: We show how the extendability of a partial coloring into an equitable coloring can be modeled via network flows. Thus, we obtain pruning rules which can be checked via flow algorithms. Computational experiments show that the search tree of enumerative algorithms can be significantly reduced in size by these rules and, in most instances, such naive approach even yields a faster algorithm. Moreover, the stability, i.e., the number of solved instances within a given time limit, is greatly improved. Since the execution of flow algorithms at each node of a search tree is time consuming, we derive arithmetic pruning rules (generalized Hall-conditions) from the network model. Adding these rules to an enumerative algorithm yields an even larger runtime improvement. Y1 - 2016 U6 - http://dx.doi.org/10.48550/arXiv.1607.08754 N1 - Lehrstuhl II für Mathematik, RWTH Aachen University SP - 1 EP - 30 ER - TY - JOUR A1 - Beckenbach, Isabel A1 - Scheidweiler, Robert T1 - Perfect ƒ-Matchings and ƒ-Factors in Hypergraphs - A Combinatorial Approach JF - Discrete Mathematics N2 - We prove characterizations of the existence of perfect ƒ-matchings in uniform mengerian and perfect hypergraphs. Moreover, we investigate the ƒ-factor problem in balanced hypergraphs. For uniform balanced hypergraphs we prove two existence theorems with purely combinatorial arguments, whereas for non-uniform balanced hypergraphs we show that the ƒ-factor problem is NP-hard. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.disc.2017.05.005 SN - 2192-7782 N1 - Als Volltext auch bei ZIB (Zuse Institute Berlin) VL - 240 IS - 10 SP - 2499 EP - 2506 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Scheidweiler, Robert A1 - Triesch, Eberhard T1 - A note on the duality between matchings and vertex covers in balanced hypergraphs JF - Journal of Combinatorial Optimization N2 - We present a new Min-Max theorem for an optimization problem closely connected to matchings and vertex covers in balanced hypergraphs. The result generalizes Kőnig’s Theorem (Berge and Las Vergnas in Ann N Y Acad Sci 175:32–40, 1970; Fulkerson et al. in Math Progr Study 1:120–132, 1974) and Hall’s Theorem (Conforti et al. in Combinatorica 16:325–329, 1996) for balanced hypergraphs. KW - Hall’s Theorem KW - Koenig’s Theorem KW - Duality KW - Balanced hypergraph KW - Hypergraph KW - Vertex cover KW - Matching Y1 - 2016 U6 - http://dx.doi.org/10.1007/s10878-015-9887-5 SN - 1573-2886 N1 - Lehrstuhl II für Mathematik RWTH Aachen VL - 32 IS - 2 SP - 639 EP - 644 PB - Springer CY - Berlin ER - TY - JOUR A1 - Rieper, Harald A1 - Gebhardt, Andreas A1 - Stucker, Brent T1 - Selective Laser Melting of the Eutectic Silver-Copper Alloy Ag 28 wt % Cu JF - RTejournal - Forum für Rapid Technologie N2 - The aim of this work was to perform a detailed investigation of the use of Selective Laser Melting (SLM) technology to process eutectic silver-copper alloy Ag 28 wt. % Cu (also called AgCu28). The processing occurred with a Realizer SLM 50 desktop machine. The powder analysis (SEM-topography, EDX, particle distribution) was reported as well as the absorption rates for the near-infrared (NIR) spectrum. Microscope imaging showed the surface topography of the manufactured parts. Furthermore, microsections were conducted for the analysis of porosity. The Design of Experiments approach used the response surface method in order to model the statistical relationship between laser power, spot distance and pulse time. KW - SLM KW - Response Surface Method KW - Porositat KW - Eutectic Silver Copper alloy KW - Additive Manufacturing Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?nbn:de:0009-2-44141 SN - 1614-0923 VL - 13 ER - TY - CHAP A1 - Kessler, Julia A1 - Balc, Nicolae A1 - Gebhardt, Andreas T1 - Basic research on lattice structures focused on the strut shape and welding beads T2 - Physics Procedia Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.phpro.2016.08.086 SN - 1875-3884 N1 - Laser Assisted Net Shape Engineering 9th International Conference on Photonic Technologies Proceedings of the LANE 2016 VL - Vol. 83 SP - 833 EP - 838 ER - TY - CHAP A1 - Kleine, Harald A1 - Kallweit, Stephan A1 - Michaux, Frank A1 - Havermann, Marc A1 - Olivier, Herbert T1 - PIV Measurement of Shock Wave Diffraction T2 - 18th International Symposium on Applications of Laser Techniques to Fluid Mechanics, 2016, Lissabon Y1 - 2016 SP - 1 EP - 14 ER - TY - CHAP A1 - Schleupen, Josef A1 - Engemann, Heiko A1 - Bagheri, Mohsen A1 - Kallweit, Stephan T1 - The potential of SMART climbing robot combined with a weatherproof cabin for rotor blade maintenance T2 - 17th European Conference on Composite Materials – ECCM, Munich, Germany Y1 - 2016 N1 - ECCM 17 SP - 1 EP - 8 ER - TY - CHAP A1 - Rieper, Harald A1 - Gebhardt, Andreas A1 - Stucker, Brent T1 - Process parameters for Selective Laser Melting of AgCu7 T2 - DDMC, Fraunhofer Direct Digital Manufacturing Conference, 3 Y1 - 2016 SN - 978-3-8396-1001-5 N1 - DDMC, 2016, Fraunhofer Direct Digital Manufacturing Conference, 3rd, Berlin, DE, 2016-03-16 - 2016-03-17 SP - 171 EP - 176 PB - Fraunhofer-Verlag CY - Stuttgart ER - TY - CHAP A1 - König, Johannes Alexander A1 - Wolf, Martin T1 - A new definition of competence developing games - and a framework to assess them T2 - ACHI 2016 : The Ninth International Conference on Advances in Computer-Human Interactions N2 - There are different types of games that try to make use of the motivation of a gaming situation in learning contexts. This paper introduces the new terminology ‘Competence Developing Game’ (CDG) as an umbrella term for all games with this intention. Based on this new terminology, an assessment framework has been developed and validated in scope of an empirical study. Now, all different types of CDGs can be evaluated according to a defined and uniform set of assessment criteria and, thus, are comparable according to their characteristics and effectiveness. KW - Serious Games KW - Gamification KW - Business Simulations KW - Assessment Y1 - 2016 SN - 978-1-61208-468-8 N1 - Proceeding of the Ninth International Conference on Advances in Computer-Human Interactions (ACHI 2016), Venice. SP - 95 EP - 97 ER - TY - CHAP A1 - Frotscher, Ralf A1 - Goßmann, Matthias A1 - Raatschen, Hans-Jürgen A1 - Temiz Artmann, Aysegül A1 - Staat, Manfred T1 - Simulation of cardiac cell-seeded membranes using the edge-based smoothed FEM T2 - Shell and membrane theories in mechanics and biology. (Advanced structured materials ; 45) N2 - We present an electromechanically coupled Finite Element model for cardiac tissue. It bases on the mechanical model for cardiac tissue of Hunter et al. that we couple to the McAllister-Noble-Tsien electrophysiological model of purkinje fibre cells. The corresponding system of ordinary differential equations is implemented on the level of the constitutive equations in a geometrically and physically nonlinear version of the so-called edge-based smoothed FEM for plates. Mechanical material parameters are determined from our own pressure-deflection experimental setup. The main purpose of the model is to further examine the experimental results not only on mechanical but also on electrophysiological level down to ion channel gates. Moreover, we present first drug treatment simulations and validate the model with respect to the experiments. Y1 - 2015 SN - 978-3-319-02534-6 ; 978-3-319-02535-3 SP - 187 EP - 212 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Selective Laser Melting of Soda-Lime Glass Powder JF - International Journal of Applied Ceramic Technology Y1 - 2015 U6 - http://dx.doi.org/10.1111/ijac.12338 SN - 1744-7402 VL - 12 IS - 1 SP - 53 EP - 61 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Process Parameters Development of Selective Laser Melting of Lunar Regolith for On-Site Manufacturing Applications JF - International Journal of Applied Ceramic Technology Y1 - 2015 SN - 1744-7402 U6 - http://dx.doi.org/10.1111/ijac.12326 VL - 12 IS - 1 SP - 46 EP - 52 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Additive manufactured mechanical disentanglement lock JF - RTejournal - Forum für Rapid Technologie Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0009-2-42147 SN - 1614-0923 VL - 12 PB - Fachhochschule Aachen CY - Aachen ER - TY - CHAP A1 - Großmann, Agnes A1 - Gabrielli, Roland Antonius A1 - Herdrich, Georg A1 - Fasoulas, Stefanos A1 - Schnauffer, Peter A1 - Middendorf, Peter A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Overview of the MultiRob 3D Lunar Industrial Development Project T2 - Conference Contribution for the 30th ISTS, Kobe, Japan, 04.07.-10.07.2015 Y1 - 2015 ER - TY - CHAP A1 - Ferrein, Alexander A1 - Kallweit, Stephan A1 - Scholl, Ingrid A1 - Reichert, Walter T1 - Learning to Program Mobile Robots in the ROS Summer School Series T2 - Proceedings 6th International Conference on Robotics in Education (RiE 15) N2 - The main objective of our ROS Summer School series is to introduce MA level students to program mobile robots with the Robot Operating System (ROS). ROS is a robot middleware that is used my many research institutions world-wide. Therefore, many state-of-the-art algorithms of mobile robotics are available in ROS and can be deployed very easily. As a basic robot platform we deploy a 1/10 RC cart that is wquipped with an Arduino micro-controller to control the servo motors, and an embedded PC that runs ROS. In two weeks, participants get to learn the basics of mobile robotics hands-on. We describe our teaching concepts and our curriculum and report on the learning success of our students. Y1 - 2015 ER - TY - CHAP A1 - Gregorio, Fabrizio de A1 - Fatigati, Giovanni A1 - Kallweit, Stephan T1 - Tiltrotor airframe flow field characterization by SPIV T2 - 11th International Symposium on Partivle Image Velocimetry - PIV15 , Santa Barbara, California, Sept 14-16, 2015 Y1 - 2015 ER - TY - CHAP A1 - Alhwarin, Faraj A1 - Ferrein, Alexander A1 - Gebhardt, Andreas A1 - Kallweit, Stephan A1 - Scholl, Ingrid A1 - Tedjasukmana, Osmond Sanjaya T1 - Improving additive manufacturing by image processing and robotic milling T2 - 2015 IEEE International Conference on Automation Science and Engineering (CASE), Aug 24-28, 2015 Gothenburg, Sweden Y1 - 2015 U6 - http://dx.doi.org/10.1109/CoASE.2015.7294217 SP - 924 EP - 929 ER - TY - JOUR A1 - Kessler, Julia A1 - Balc, Nicolae A1 - Gebhardt, Andreas A1 - Abbas, Karim T1 - Basic Research on Lattice Structures Focused on the Tensile Strength JF - Applied Mechanics and Materials Y1 - 2015 U6 - http://dx.doi.org/10.4028/www.scientific.net/AMM.808.193 SN - 1662-7482 N1 - MTeM ; October 14-16, 2015, Cluj-Napoca, Romania VL - Vol. 808 SP - 193 EP - 198 PB - Trans Tech Publications CY - Bäch ER - TY - CHAP A1 - Fateri, Miranda A1 - Gebhardt, Andreas A1 - Gabrielli, Roland Antonius A1 - Herdrich, Georg A1 - Fasoulas, Stefanos A1 - Großmann, Agnes A1 - Schnauffer, Peter A1 - Middendorf, Peter T1 - Additive Manufacturing of Lunar Regolith for Extra-terrestrial Industry Plant T2 - International Symposium on Space Technology and Science (ICTS). July 2015, Kobe, Japan Y1 - 2015 ER - TY - CHAP A1 - Gabrielli, Roland Antonius A1 - Mathies, Johannes A1 - Großmann, Agnes A1 - Herdrich, Georg A1 - Fasoulas, Stefanos A1 - Middendorf, Peter A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Space Propulsion Considerations for a Lunar Take Off Industry Based on Regolith T2 - International Symposium on Space Technology and Science (ISTS). July 2015, Kobe, Japan Y1 - 2015 ER -