@inproceedings{NursinskiStolbergGangatharanCzarnecki2016, author = {Nursinski-Stolberg, Andr{\´e} and Gangatharan, Kiritharan and Czarnecki, Christian}, title = {Development of a subject-oriented reference process model for the telecommunications industry}, series = {GI Edition Proceedings Band 259 INFORMATIK 2016}, booktitle = {GI Edition Proceedings Band 259 INFORMATIK 2016}, editor = {Mayr, Heinrich C. and Pinzger, Martin}, publisher = {Gesellschaft f{\"u}r Informatik e.V.}, address = {Bonn}, isbn = {9783885796534}, issn = {1617-5468}, pages = {699 -- 712}, year = {2016}, abstract = {Generally the usage of reference models can be structured top-down or bottom-up. The practical need of agile change and flexible organizational implementation requires a consistent mapping to an operational level. In this context, well-established reference process models are typically structured top-down. The subject-oriented Business Process Management (sBPM) offers a modeling concept that is structured bottom-up and concentrates on the process actors on an operational level. This paper applies sBPM to the enhanced Telecom Operations Map (eTOM), a well-accepted reference process model in the telecommunications industry. The resulting design artifact is a concrete example for a combination of a bottom-up and top-down developed reference model. The results are evaluated and confirmed in practical context through the involvement of the industry body TMForum.}, language = {en} } @article{KosterScheidweilerTieves2016, author = {Koster, Arie and Scheidweiler, Robert and Tieves, Martin}, title = {A flow based pruning scheme for enumerative equitable coloring algorithms}, series = {A flow based pruning scheme for enumerative equitable coloring algorithms}, journal = {A flow based pruning scheme for enumerative equitable coloring algorithms}, doi = {10.48550/arXiv.1607.08754}, pages = {1 -- 30}, year = {2016}, abstract = {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.}, language = {en} } @article{BeckenbachScheidweiler2016, author = {Beckenbach, Isabel and Scheidweiler, Robert}, title = {Perfect ƒ-Matchings and ƒ-Factors in Hypergraphs - A Combinatorial Approach}, series = {Discrete Mathematics}, volume = {240}, journal = {Discrete Mathematics}, number = {10}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2192-7782}, doi = {10.1016/j.disc.2017.05.005}, pages = {2499 -- 2506}, year = {2016}, abstract = {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.}, language = {en} } @article{ScheidweilerTriesch2016, author = {Scheidweiler, Robert and Triesch, Eberhard}, title = {A note on the duality between matchings and vertex covers in balanced hypergraphs}, series = {Journal of Combinatorial Optimization}, volume = {32}, journal = {Journal of Combinatorial Optimization}, number = {2}, publisher = {Springer}, address = {Berlin}, issn = {1573-2886}, doi = {10.1007/s10878-015-9887-5}, pages = {639 -- 644}, year = {2016}, abstract = {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.}, language = {en} } @article{NiedermeyerZhouDursunetal.2016, author = {Niedermeyer, Angela and Zhou, Bei and Dursun, G{\"o}zde and Temiz Artmann, Ayseg{\"u}l and Markert, Bernd}, title = {An examination of tissue engineered scaffolds in a bioreactor}, series = {Proceedings in Applied Mathematics and Mechanics PAMM}, volume = {16}, journal = {Proceedings in Applied Mathematics and Mechanics PAMM}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1617-7061}, doi = {10.1002/pamm.201610038}, pages = {99 -- 100}, year = {2016}, abstract = {Replacement tissues, designed to fill in articular cartilage defects, should exhibit the same properties as the native material. The aim of this study is to foster the understanding of, firstly, the mechanical behavior of the material itself and, secondly, the influence of cultivation parameters on cell seeded implants as well as on cell migration into acellular implants. In this study, acellular cartilage replacement material is theoretically, numerically and experimentally investigated regarding its viscoelastic properties, where a phenomenological model for practical applications is developed. Furthermore, remodeling and cell migration are investigated.}, language = {en} } @inproceedings{HoevelerJanser2016, author = {Hoeveler, Bastian and Janser, Frank}, title = {The aerodynamically optimized design of a fan-in-wing duct}, series = {Applied Aerodynamics Research Conference 2016, Bristol, GB, Jul 19-21, 2016}, booktitle = {Applied Aerodynamics Research Conference 2016, Bristol, GB, Jul 19-21, 2016}, isbn = {1-85768-371-4}, pages = {1 -- 10}, year = {2016}, language = {en} } @inproceedings{OttenSchmidtWeber2016, author = {Otten, D. and Schmidt, M. and Weber, Tobias}, title = {Advances in Determination of Material Parameters for Functional Simulations Based on Process Simulations}, series = {SAMPE Europe Conference 16 Liege}, booktitle = {SAMPE Europe Conference 16 Liege}, isbn = {978-1-5108-3800-0}, pages = {570 -- 577}, year = {2016}, language = {en} } @inproceedings{WeberTellisDuhovic2016, author = {Weber, Tobias and Tellis, Jane J. and Duhovic, Miro}, title = {Characterization of tool-part-interaction an interlaminar friction for manufacturing process simulation}, series = {ECCM 17, 17th European Conference on Composite Materials, M{\"u}nchen, DE, Jun 26-30, 2016}, booktitle = {ECCM 17, 17th European Conference on Composite Materials, M{\"u}nchen, DE, Jun 26-30, 2016}, isbn = {978-3-00-053387-7}, pages = {1 -- 7}, year = {2016}, language = {en} } @article{WeberArentMuenchetal.2016, author = {Weber, Tobias and Arent, Jan-Christoph and M{\"u}nch, Lukas and Duhovic, Miro and Balvers, Johannes M.}, title = {A fast method for the generation of boundary conditions for thermal autoclave simulation}, series = {Composites Part A}, volume = {88}, journal = {Composites Part A}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1359-835X}, doi = {10.1016/j.compositesa.2016.05.036}, pages = {216 -- 225}, year = {2016}, abstract = {Manufacturing process simulation enables the evaluation and improvement of autoclave mold concepts early in the design phase. To achieve a high part quality at low cycle times, the thermal behavior of the autoclave mold can be investigated by means of simulations. Most challenging for such a simulation is the generation of necessary boundary conditions. Heat-up and temperature distribution in an autoclave mold are governed by flow phenomena, tooling material and shape, position within the autoclave, and the chosen autoclave cycle. This paper identifies and summarizes the most important factors influencing mold heat-up and how they can be introduced into a thermal simulation. Thermal measurements are used to quantify the impact of the various parameters. Finally, the gained knowledge is applied to develop a semi-empirical approach for boundary condition estimation that enables a simple and fast thermal simulation of the autoclave curing process with reasonably high accuracy for tooling optimization.}, language = {en} } @article{SvaneborgKarimiVarzanehHojdisetal.2016, author = {Svaneborg, Carsten and Karimi-Varzaneh, Hossein Ali and Hojdis, Nils and Fleck, Franz and Everaers, Ralf}, title = {Multiscale approach to equilibrating model polymer melts}, series = {Physical Review E}, volume = {94}, journal = {Physical Review E}, number = {032502}, publisher = {AIP Publishing}, address = {Melville, NY}, issn = {2470-0053}, doi = {10.1103/PhysRevE.94.032502}, year = {2016}, abstract = {We present an effective and simple multiscale method for equilibrating Kremer Grest model polymer melts of varying stiffness. In our approach, we progressively equilibrate the melt structure above the tube scale, inside the tube and finally at the monomeric scale. We make use of models designed to be computationally effective at each scale. Density fluctuations in the melt structure above the tube scale are minimized through a Monte Carlo simulated annealing of a lattice polymer model. Subsequently the melt structure below the tube scale is equilibrated via the Rouse dynamics of a force-capped Kremer-Grest model that allows chains to partially interpenetrate. Finally the Kremer-Grest force field is introduced to freeze the topological state and enforce correct monomer packing. We generate 15 melts of 500 chains of 10.000 beads for varying chain stiffness as well as a number of melts with 1.000 chains of 15.000 monomers. To validate the equilibration process we study the time evolution of bulk, collective, and single-chain observables at the monomeric, mesoscopic, and macroscopic length scales. Extension of the present method to longer, branched, or polydisperse chains, and/or larger system sizes is straightforward.}, language = {en} }