@article{HildebrandHechtBliedtneretal., author = {Hildebrand, J{\"o}rg and Hecht, Kerstin and Bliedtner, Jens and M{\"u}ller, Hartmut}, title = {Advanced Analysis of Laser Beam Polishing of Quartz Glass Surfaces}, series = {Physics Procedia}, journal = {Physics Procedia}, doi = {10.1016/j.phpro.2012.10.039}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170418-31372}, pages = {277 -- 285}, abstract = {The laser beam is a small, flexible and fast polishing tool. With laser radiation it is possible to finish many outlines or geometries on quartz glass surfaces in the shortest possible time. It's a fact that the temperature developing while polishing determines the reachable surface smoothing and, as a negative result, causes material tensions. To find out which parameters are important for the laser polishing process and the surface roughness respectively and to estimate material tensions, temperature simulations and extensive polishing experiments took place. During these experiments starting and machining parameters were changed and temperatures were measured contact-free. The accuracy of thermal and mechanical simulation was improved in the case of advanced FE-analysis.}, subject = {Laser}, language = {en} } @article{KoehlerKoenig, author = {K{\"o}hler, Hermann and K{\"o}nig, Reinhard}, title = {Aktionsr{\"a}ume in Dresden}, doi = {10.25643/bauhaus-universitaet.2672}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160822-26726}, abstract = {In vorliegender Studie werden die Aktionsr{\"a}ume von Befragten in Dresden {\"u}ber eine standardisierte Befragung (n=360) untersucht. Die den Aktionsr{\"a}umen zugrundeliegenden Aktivit{\"a}ten werden unterschieden in Einkaufen f{\"u}r den t{\"a}glichen Bedarf, Ausgehen (z.B. in Caf{\´e}, Kneipe, Gastst{\"a}tte), Erholung im Freien (z.B. spazieren gehen, Nutzung von Gr{\"u}nanlagen) und private Geselligkeit (z.B. Feiern, Besuch von Verwandten/Freunden). Der Aktionsradius wird unterschieden in Wohnviertel, Nachbarviertel und sonstiges weiteres Stadtgebiet. Um aus den vier betrachteten Aktivit{\"a}ten einen umfassenden Kennwert f{\"u}r den durchschnittlichen Aktionsradius eines Befragten zu bilden, wird ein Modell f{\"u}r den Kennwert eines Aktionsradius entwickelt. Die Studie kommt zu dem Ergebnis, dass das Alter der Befragten einen signifikanten - wenn auch geringen - Einfluss auf den Aktionsradius hat. Das Haushaltsnettoeinkommen hat einen mit Einschr{\"a}nkung signifikanten, ebenfalls geringen Einfluss auf allt{\"a}gliche Aktivit{\"a}ten der Befragten.}, subject = {Aktionsraumforschung}, language = {de} } @article{Koehler, author = {K{\"o}hler, Hermann}, title = {Ergebnisse der Befragung zu Wohnstandortpr{\"a}ferenzen von Lebensweltsegmenten in Dresden}, doi = {10.25643/bauhaus-universitaet.2670}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160822-26704}, abstract = {In vorliegender Studie werden die Wohnstandortpr{\"a}ferenzen der Sinus-Milieugruppen in Dresden {\"u}ber eine standardisierte Befragung (n=318) untersucht. Es wird unterschieden zwischen handlungsleitenden Wohnstandortpr{\"a}ferenzen, die durch Anhaltspunkte auf der Handlungsebene st{\"a}rker in Betracht gezogen werden sollten, und Wohnstandortpr{\"a}ferenzen, welche eher orientierenden Charakter haben. Die Wohnstandortpr{\"a}ferenzen werden untersucht anhand der Kategorien Ausstattung/Zustand der Wohnung/des n{\"a}heren Wohnumfeldes, Versorgungsstruktur, soziales Umfeld, Baustrukturtyp, Ortsgebundenheit sowie des Aspektes des Images eines Stadtviertels. Um die Befragten den Sinus-Milieugruppen zuordnen zu k{\"o}nnen, wird ein Lebensweltsegment-Modell entwickelt, welches den Anspruch hat, die Sinus-Milieugruppen in der Tendenz abzubilden. Die Studie kommt zu dem Ergebnis, dass die Angeh{\"o}rigen der verschiedenen Lebensweltsegmente in jeder Kategorie - wenn auch z.T. auf geringerem Niveau - signifikante Unterschiede in der Bewertung einzelner Wohnstandortpr{\"a}ferenzen aufweisen.}, subject = {Milieuforschung}, language = {de} } @article{TonnTatarin, author = {Tonn, Christian and Tatarin, Ren{\´e}}, title = {Volumen Rendering in der Architektur: {\"U}berlagerung und Kombination von 3D Voxel Volumendaten mit 3D Geb{\"a}udemodellen}, doi = {10.25643/bauhaus-universitaet.2671}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160822-26718}, abstract = {Volumerendering ist eine Darstellungstechnik, um verschiedene r{\"a}umliche Mess- und Simulationsdaten anschaulich, interaktiv grafisch darzustellen. Im folgenden Beitrag wird ein Verfahren vorgestellt, mehrere Volumendaten mit einem Architekturfl{\"a}chenmodell zu {\"u}berlagern. Diese komplexe Darstellungsberechnung findet mit hardwarebeschleunigten Shadern auf der Grafikkarte statt. Im Beitrag wird hierzu der implementierte Softwareprototyp "VolumeRendering" vorgestellt. Neben dem interaktiven Berechnungsverfahren wurde ebenso Wert auf eine nutzerfreundliche Bedienung gelegt. Das Ziel bestand darin, eine einfache Bewertung der Volumendaten durch Fachplaner zu erm{\"o}glichen. Durch die {\"U}berlagerung, z. B. verschiedener Messverfahren mit einem Fl{\"a}chenmodell, ergeben sich Synergien und neue Auswertungsm{\"o}glichkeiten. Abschließend wird anhand von Beispielen aus einem interdisziplin{\"a}ren Forschungsprojekt die Anwendung des Softwareprototyps illustriert.}, subject = {Multiple Volume Rendering}, language = {de} } @article{Kalisch, author = {Kalisch, Dominik}, title = {Wissen wer wo wohnt}, doi = {10.25643/bauhaus-universitaet.2669}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160822-26695}, abstract = {In cities people live together in neighbourhoods. Here they can find the infrastructure they need, starting with shops for the daily purpose to the life-cycle based infrastructures like kindergartens or nursing homes. But not all neighbourhoods are identical. The infrastructure mixture varies from neighbourhood to neighbourhood, but different people have different needs which can change e.g. based on the life cycle situation or their affiliation to a specific milieu. We can assume that a person or family tries to settle in a specific neighbourhood that satisfies their needs. So, if the residents are happy with a neighbourhood, we can further assume that this neighbourhood satisfies their needs. The socio-oeconomic panel (SOEP) of the German Institute for Economy (DIW) is a survey that investigates the economic structure of the German population. Every four years one part of this survey includes questions about what infrastructures can be found in the respondents neighbourhood and the satisfaction of the respondent with their neighbourhood. Further, it is possible to add a milieu estimation for each respondent or household. This gives us the possibility to analyse the typical neighbourhoods in German cities as well as the infrastructure profiles of the different milieus. Therefore, we take the environment variables from the dataset and recode them into a binary variable - whether an infrastructure is available or not. According to Faust (2005), these sets can also be understood, as a network of actors in a neighbourhood, which share two, three or more infrastructures. Like these networks, this neighbourhood network can also be visualized as a bipartite affiliation network and therefore analysed using correspondence analysis. We will show how a neighbourhood analysis will benefit from an upstream correspondence analysis and how this could be done. We will also present and discuss the results of such an analysis.}, subject = {urban planning}, language = {de} } @article{Aguinaga, author = {Aguinaga, Jos{\´e} Guillermo De}, title = {Error in prediction due to data type availability in a coupled hydro-mechanical model}, series = {Electronic Journal of Geotechnical Engineering}, journal = {Electronic Journal of Geotechnical Engineering}, doi = {10.25643/bauhaus-universitaet.3117}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170413-31170}, pages = {2459 -- 2471}, abstract = {Different types of data provide different type of information. The present research analyzes the error on prediction obtained under different data type availability for calibration. The contribution of different measurement types to model calibration and prognosis are evaluated. A coupled 2D hydro-mechanical model of a water retaining dam is taken as an example. Here, the mean effective stress in the porous skeleton is reduced due to an increase in pore water pressure under drawdown conditions. Relevant model parameters are identified by scaled sensitivities. Then, Particle Swarm Optimization is applied to determine the optimal parameter values and finally, the error in prognosis is determined. We compare the predictions of the optimized models with results from a forward run of the reference model to obtain the actual prediction errors. The analyses presented here were performed calibrating the hydro-mechanical model to 31 data sets of 100 observations of varying data types. The prognosis results improve when using diversified information for calibration. However, when using several types of information, the number of observations has to be increased to be able to cover a representative part of the model domain. For an analysis with constant number of observations, a compromise between data type availability and domain coverage proves to be the best solution. Which type of calibration information contributes to the best prognoses could not be determined in advance. The error in model prognosis does not depend on the error in calibration, but on the parameter error, which unfortunately cannot be determined in inverse problems since we do not know its real value. The best prognoses were obtained independent of calibration fit. However, excellent calibration fits led to an increase in prognosis error variation. In the case of excellent fits; parameters' values came near the limits of reasonable physical values more often. To improve the prognoses reliability, the expected value of the parameters should be considered as prior information on the optimization algorithm.}, subject = {Sensitivit{\"a}tsanalyse}, language = {en} } @article{NguyenVinhBakarMsekhetal., author = {Nguyen-Vinh, H. and Bakar, I. and Msekh, Mohammed Abdulrazzak and Song, Jeong-Hoon and Muthu, Jacob and Zi, Goangseup and Le, P. and Bordas, St{\´e}phane Pierre Alain and Simpson, R. and Natarajan, S. and Lahmer, Tom and Rabczuk, Timon}, title = {Extended Finite Element Method for Dynamic Fracture of Piezo-Electric Materials}, series = {Engineering Fracture Mechanics}, journal = {Engineering Fracture Mechanics}, doi = {10.1016/j.engfracmech.2012.04.025}, pages = {19 -- 31}, abstract = {We present an extended finite element formulation for dynamic fracture of piezo-electric materials. The method is developed in the context of linear elastic fracture mechanics. It is applied to mode I and mixed mode-fracture for quasi-steady cracks. An implicit time integration scheme is exploited. The results are compared to results obtained with the boundary element method and show excellent agreement.}, subject = {Angewandte Mathematik}, language = {en} } @article{AreiasRabczukDiasdaCostaetal., author = {Areias, Pedro and Rabczuk, Timon and Dias-da-Costa, D. and Piresh, E.B.}, title = {Implicit solutions with consistent additive and multiplicative components}, series = {Finite Elements in Analysis and Design}, journal = {Finite Elements in Analysis and Design}, doi = {10.1016/j.finel.2012.03.007}, pages = {15 -- 31}, abstract = {This work describes an algorithm and corresponding software for incorporating general nonlinear multiple-point equality constraints in a implicit sparse direct solver. It is shown that direct addressing of sparse matrices is possible in general circumstances, circumventing the traditional linear or binary search for introducing (generalized) constituents to a sparse matrix. Nested and arbitrarily interconnected multiple-point constraints are introduced by processing of multiplicative constituents with a built-in topological ordering of the resulting directed graph. A classification of discretization methods is performed and some re-classified problems are described and solved under this proposed perspective. The dependence relations between solution methods, algorithms and constituents becomes apparent. Fracture algorithms can be naturally casted in this framework. Solutions based on control equations are also directly incorporated as equality constraints. We show that arbitrary constituents can be used as long as the resulting directed graph is acyclic. It is also shown that graph partitions and orderings should be performed in the innermost part of the algorithm, a fact with some peculiar consequences. The core of our implicit code is described, specifically new algorithms for direct access of sparse matrices (by means of the clique structure) and general constituent processing. It is demonstrated that the graph structure of the second derivatives of the equality constraints are cliques (or pseudo-elements) and are naturally included as such. A complete algorithm is presented which allows a complete automation of equality constraints, avoiding the need of pre-sorting. Verification applications in four distinct areas are shown: single and multiple rigid body dynamics, solution control and computational fracture.}, subject = {Angewandte Mathematik}, language = {en} } @article{JiangWangRabczuk, author = {Jiang, Jin-Wu and Wang, Bing-Shen and Rabczuk, Timon}, title = {Acoustic and breathing phonon modes in bilayer graphene with Moire-acute patterns}, series = {Applied Physics Letters}, journal = {Applied Physics Letters}, doi = {10.1063/1.4735246}, abstract = {The lattice dynamics properties are investigated for twisting bilayer graphene. There are big jumps for the inter-layer potential at twisting angle θ=0° and 60°, implying the stability of Bernal-stacking and the instability of AA-stacking structures, while a long platform in [8,55]° indicates the ease of twisting bilayer graphene in this wide angle range. Significant frequency shifts are observed for the z breathing mode around θ=0° and 60°, while the frequency is a constant in a wide range [8,55]°. Using the z breathing mode, a mechanical nanoresonator is proposed to operate on a robust resonant frequency in terahertz range.}, subject = {Angewandte Mathematik}, language = {en} } @article{JiangZhaoZhouetal., author = {Jiang, Jin-Wu and Zhao, Jun-Hua and Zhou, K. and Rabczuk, Timon}, title = {Superior thermal conductivity and extremely high mechanical strength in polyethylene chains from ab initio calculation}, series = {Journal of Applied Physics}, journal = {Journal of Applied Physics}, doi = {10.1063/1.4729489}, abstract = {The upper limit of the thermal conductivity and the mechanical strength are predicted for the polyethylene chain, by performing the ab initio calculation and applying the quantum mechanical non-equilibrium Green's function approach. Specially, there are two main findings from our calculation: (1) the thermal conductivity can reach a high value of 310 Wm-1 K-1 in a 100 nm polyethylene chain at room temperature and the thermal conductivity increases with the length of the chain; (2) the Young's modulus in the polyethylene chain is as high as 374.5 GPa, and the polyethylene chain can sustain 32.85\%±0.05\% (ultimate) strain before undergoing structural phase transition into gaseous ethylene.}, subject = {Angewandte Mathematik}, language = {en} }