TY - JOUR A1 - Zhuang, Xiaoying A1 - Huang, Runqiu A1 - Rabczuk, Timon A1 - Liang, C. T1 - A coupled thermo-hydro-mechanical model of jointed hard rock for compressed air energy storage JF - Mathematical Problems in Engineering N2 - A coupled thermo-hydro-mechanical model of jointed hard rock for compressed air energy storage KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 ER - TY - JOUR A1 - Zhuang, Xiaoying A1 - Huang, Runqiu A1 - Liang, Chao A1 - Rabczuk, Timon T1 - A coupled thermo-hydro-mechanical model of jointed hard rock for compressed air energy storage JF - Mathematical Problems in Engineering N2 - Renewable energy resources such as wind and solar are intermittent, which causes instability when being connected to utility grid of electricity. Compressed air energy storage (CAES) provides an economic and technical viable solution to this problem by utilizing subsurface rock cavern to store the electricity generated by renewable energy in the form of compressed air. Though CAES has been used for over three decades, it is only restricted to salt rock or aquifers for air tightness reason. In this paper, the technical feasibility of utilizing hard rock for CAES is investigated by using a coupled thermo-hydro-mechanical (THM) modelling of nonisothermal gas flow. Governing equations are derived from the rules of energy balance, mass balance, and static equilibrium. Cyclic volumetric mass source and heat source models are applied to simulate the gas injection and production. Evaluation is carried out for intact rock and rock with discrete crack, respectively. In both cases, the heat and pressure losses using air mass control and supplementary air injection are compared. KW - Energiespeicherung KW - Druckluft KW - Kaverne KW - Modellierung Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170428-31726 ER - TY - JOUR A1 - Zhao, Jun-Hua A1 - Lu, Lixin A1 - Rabczuk, Timon T1 - Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines JF - The Journal of Chemical Physics N2 - Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 U6 - http://dx.doi.org/10.1063/1.4878115 ER - TY - JOUR A1 - Zhao, Jun-Hua A1 - Kou, Liangzhi A1 - Jiang, Jin-Wu A1 - Rabczuk, Timon T1 - Tension-induced phase transition of single-layer molybdenum disulphide (MoS2) at low temperatures JF - Nanotechnology N2 - Tension-induced phase transition of single-layer molybdenum disulphide (MoS2) at low temperatures KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 U6 - http://dx.doi.org/10.1088/0957-4484/25/29/295701 ER - TY - JOUR A1 - Zhao, Jun-Hua A1 - Jiang, Jin-Wu A1 - Jia, Yue A1 - Guo, Wanlin A1 - Rabczuk, Timon T1 - A theoretical analysis of cohesive energy between carbon nanotubes, graphene and substrates JF - Carbon N2 - Explicit solutions for the cohesive energy between carbon nanotubes, graphene and substrates are obtained through continuum modeling of the van der Waals interaction between them. The dependence of the cohesive energy on their size, spacing and crossing angles is analyzed. Checking against full atom molecular dynamics calculations and available experimental results shows that the continuum solution has high accuracy. The equilibrium distances between the nanotubes, graphene and substrates with minimum cohesive energy are also provided explicitly. The obtained analytical solution should be of great help for understanding the interaction between the nanostructures and substrates, and designing composites and nanoelectromechanical systems. KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.carbon.2013.01.041 SP - 108 EP - 119 ER - TY - THES A1 - Zhao, Jun-Hua T1 - Multiscale modeling of nanodevices based on carbon nanotubes and polymers T1 - Multiskalige Modellierung von auf Kohlenstoffnanoröhren und Polymeren basierenden Nanobauteilen N2 - This thesis concerns the physical and mechanical interactions on carbon nanotubes and polymers by multiscale modeling. CNTs have attracted considerable interests in view of their unique mechanical, electronic, thermal, optical and structural properties, which enable them to have many potential applications. Carbon nanotube exists in several structure forms, from individual single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) to carbon nanotube bundles and networks. The mechanical properties of SWCNTs and MWCNTs have been extensively studied by continuum modeling and molecular dynamics (MD) simulations in the past decade since the properties could be important in the CNT-based devices. CNT bundles and networks feature outstanding mechanical performance and hierarchical structures and network topologies, which have been taken as a potential saving-energy material. In the synthesis of nanocomposites, the formation of the CNT bundles and networks is a challenge to remain in understanding how to measure and predict the properties of such large systems. Therefore, a mesoscale method such as a coarse-grained (CG) method should be developed to study the nanomechanical characterization of CNT bundles and networks formation. In this thesis, the main contributions can be written as follows: (1) Explicit solutions for the cohesive energy between carbon nanotubes, graphene and substrates are obtained through continuum modeling of the van der Waals interaction between them. (2) The CG potentials of SWCNTs are established by a molecular mechanics model. (3) The binding energy between two parallel and crossing SWCNTs and MWCNTs is obtained by continuum modeling of the van der Waals interaction between them. Crystalline and amorphous polymers are increasingly used in modern industry as tructural materials due to its important mechanical and physical properties. For crystalline polyethylene (PE), despite its importance and the studies of available MD simulations and continuum models, the link between molecular and continuum descriptions of its mechanical properties is still not well established. For amorphous polymers, the chain length and temperature effect on their elastic and elastic-plastic properties has been reported based on the united-atom (UA) and CG MD imulations in our previous work. However, the effect of the CL and temperature on the failure behavior is not understood well yet. Especially, the failure behavior under shear has been scarcely reported in previous work. Therefore, understanding the molecular origins of macroscopic fracture behavior such as fracture energy is a fundamental scientific challenge. In this thesis, the main contributions can be written as follows: (1) An analytical molecular mechanics model is developed to obtain the size-dependent elastic properties of crystalline PE. (2) We show that the two molecular mechanics models, the stick-spiral and the beam models, predict considerably different mechanical properties of materials based on energy equivalence. The difference between the two models is independent of the materials. (3) The tensile and shear failure behavior dependence on chain length and temperature in amorphous polymers are scrutinized using molecular dynamics simulations. Finally, the influence of polymer wrapped two neighbouring SWNTs’ dispersion on their load transfer is investigated by molecular dynamics (MD) simulations, in which the SWNTs' position, the polymer chain length and the temperature on the interaction force is systematically studied. T3 - ISM-Bericht // Institut für Strukturmechanik, Bauhaus-Universität Weimar - 2014,1 KW - Mehrskalenmodell KW - Kohlenstoff Nanoröhre KW - Polymere KW - Multiscale modeling KW - Carbon nanotubes KW - Polymers Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20140130-21078 ER - TY - JOUR A1 - Zhao, Jiyun A1 - Jiang, Jin-Wu A1 - Wang, L. A1 - Guo, Wanlin A1 - Rabczuk, Timon T1 - Coarse-grained potentials of single-walled carbon nanotubes JF - Journal of the Mechanics and Physics of Solids N2 - Coarse-grained potentials of single-walled carbon nanotubes KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 ER - TY - JOUR A1 - Zhang, Yancheng A1 - Zhuang, Xiaoying A1 - Muthu, Jacob A1 - Mabrouki, Tarek A1 - Fontaine, Michaël A1 - Gong, Yadong A1 - Rabczuk, Timon T1 - Load transfer of graphene/carbon nanotube/polyethylene hybrid nanocomposite by molecular dynamics simulation JF - Composites Part B Engineering N2 - Load transfer of graphene/carbon nanotube/polyethylene hybrid nanocomposite by molecular dynamics simulation KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 SP - 27 EP - 33 ER - TY - JOUR A1 - Xu, G. A1 - Mourrain, B. A1 - Galligo, A. A1 - Rabczuk, Timon T1 - High-quality construction of analysis-suitable trivariate NURBS solids by reparameterization methods JF - Computational Mechanics N2 - High-quality construction of analysis-suitable trivariate NURBS solids by reparameterization methods KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 ER - TY - THES A1 - Wiedemeyer, Nina T1 - Buchfalten: Material Technik Gefüge der Künstlerbücher N2 - Bücher werden nicht erst seit ihrer industriellen Produktion aus gefalzten Papierbogen zusammengesetzt – schon mittelalterliche Codices wurden aus gefalteten Pergamenthäuten konstruiert. Fokus dieser Studie über das Medium Buch ist daher die Kulturtechnik der Faltung. Anders als in der philosophischen Auseinandersetzung mit dem Begriff der Falte, ist die Buchfalte keine anti-lineare Figur, sondern ein operationales Falzscharnier, welches Anordnungen im Buchraum bestimmt und Ornamente hervorbringt. Mediengeschichtliche Fragestellungen sind auf Analysen von Buchmaterial und Künstlerbüchern vom 19. Jahrhundert bis zur Gegenwart basiert. Mit den Büchern u.a. von Christian Boltanski, Hanne Darboven und Hans-Peter Feldmann werden Erkenntnisse über buchgeschichtliche Zusammenhänge gewonnen und das Künstlerbuch in eine Geschichte des Mediums Buch eingestellt. KW - Buch; Buchkunst; Falte; Ornament; Papier KW - Boltanski, Christian; Faltung; Feldmann, Hans-Peter; Künstlerbuch; Van de Velde, Henry Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20141210-23337 UR - http://e-pub.uni-weimar.de/opus4/frontdoor/index/index/docId/2252 N1 - Die Original-Arbeit (weiterführender Link) wurde auf Grund kollorierter Abbildungen zurückgezogen und mit s/w-Abbildungen neu eingestellt (Anforderung VG Wort) ER - TY - THES A1 - Wiedemeyer, Nina T1 - Buchfalten: Material Technik Gefüge der Künstlerbücher N2 - Bücher werden nicht erst seit ihrer industriellen Produktion aus gefalzten Papierbogen zusammengesetzt – schon mittelalterliche Codices wurden aus gefalteten Pergamenthäuten konstruiert. Fokus dieser Studie über das Medium Buch ist daher die Kulturtechnik der Faltung. Anders als in der philosophischen Auseinandersetzung mit dem Begriff der Falte, ist die Buchfalte keine anti-lineare Figur, sondern ein operationales Falzscharnier, welches Anordnungen im Buchraum bestimmt und Ornamente hervorbringt. Mediengeschichtliche Fragestellungen sind auf Analysen von Buchmaterial und Künstlerbüchern vom 19. Jahrhundert bis zur Gegenwart basiert. Mit den Büchern u.a. von Christian Boltanski, Hanne Darboven und Hans-Peter Feldmann werden Erkenntnisse über buchgeschichtliche Zusammenhänge gewonnen und das Künstlerbuch in eine Geschichte des Mediums Buch eingestellt. KW - Papier KW - Falte KW - Buch KW - Buchkunst KW - Ornament KW - Faltung KW - Künstlerbuch KW - Boltanski, Christian KW - Van de Velde, Henry KW - Feldmann, Hans-Peter Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20140806-22527 UR - http://e-pub.uni-weimar.de/opus4/frontdoor/index/index/docId/2333 N1 - Arbeit auf Grund kollorierter Abbildungen zurückgezogen und mit s/w-Abbildungen neu eingestellt (Anforderung VG Wort) ; Siehe Link zum aktuellen Dokument ER - TY - THES A1 - Wellnitz, Felix T1 - BAUKLIMATISCHE ERTÜCHTIGUNG UND NACHHALTIGE INSTANDSETZUNG DENKMALGESCHÜTZTER VERWALTUNGSBAUTEN DER 1950er JAHRE AM BEISPIEL DER EHEMALIGEN BAYERISCHEN LANDESVERTRETUNG VON SEP RUF IN BONN N2 - Viele Baudenkmale sind dem Konflikt aus baulichem Instandsetzungsbedarf für eine zeitgemäße Nutzung und einer sich möglicherweise daraus ergebenden Gefährdung der Denkmalsubstanz ausgesetzt. Gründe sind steigende Energiekosten für den Gebäudebetrieb, zeitgemäße Anforderungen an Behaglichkeit und Arbeitsschutz, sowie die Vermeidung von Schäden an der Substanz aufgrund baulicher Mängel des konstruktiven Wärme- und Feuchteschutzes. Gleichzeitig gilt für viele Bauten aber auch die Notwendigkeit regelmäßiger Nutzung und Bewirtschaftung, um den Erhalt überhaupt zu sichern. Die energetische Ertüchtigung von Baudenkmalen scheitert in diesem Spannungsfeld oft am unlösbaren Konflikt zwischen dem Erhalt der bauzeitlichen Substanz auf der einen und der notwendigen energetischen Optimierung der Gebäudehülle auf der anderen Seite. Zielsetzung dieser Fallstudie ist die beispielhafte Entwicklung einer bauklimatischen und denkmalgerechten Ertüchtigungsstrategie am Beispiel eines Verwaltungsgebäudes der Nachkriegsmoderne als Beitrag zur Lösung dieses Konfliktes. KW - Denkmalpflege KW - Bauklimatik KW - Bauphysik KW - Sanierung KW - Nachkriegsmoderne KW - Ertüchtigung Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20140919-23031 ER - TY - THES A1 - Walsdorf, Joern T1 - M-Learning: Lernen im mobilen Kontext an Hochschulen N2 - A fundamental characteristic of human beings is the desire to start learning at the moment of birth. The rather formal learning process that learners have to deal with in school, on vocational training or in university, is currently subject to fundamental changes. The increasing technologization, overall existing mobile devices, the ubiquitous access to digital information, and students being early adaptors of all these technological innovations require reactions on the part of the educational system. This study examines such a reaction: The use of mobile learning in higher education. Examining the subject m-learning first requires an investigation of the educational model e-learning. Many universities already established e-learning as one of their educational segments, providing a wide range of methods to support this kind of teaching. This study includes an empirical acceptance analysis regarding the general learning behavior of students and their approval of e-learning methods. A survey on the approval of m-learning supplements the results. Mobile learning is characterized by both the mobility of the communication devices and the users. Both factors lead to new correlations, demonstrate the potential of today's mobile devices and the probability to increase the learning performance. The dissertation addresses these correlations and the use of mobile devices in the context of m-learning. M-learning and the usage of mobile devices not only require a reflection from a technological point of view. In addition to the technical features of such mobile devices, the usability of their applications plays an important role, especially with regard to the limited display size. For the purpose of evaluating mobile apps and browser-based applications, various analytical methods are suitable. The concluding heuristic evaluation points out the vulnerability of an established m-learning application, reveals the need for improvement, and shows an approach to rectify the shortcoming. KW - Mobile Learning KW - M-Learning KW - E-Learning KW - Electronic Learning KW - Learning on demand KW - Mobiles Lernen Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20140304-21361 ER - TY - JOUR A1 - Völske, Michael A1 - Gollub, Tim A1 - Hagen, Matthias A1 - Stein, Benno T1 - A keyquery-based classification system for CORE JF - D-Lib Magazine N2 - We apply keyquery-based taxonomy composition to compute a classification system for the CORE dataset, a shared crawl of about 850,000 scientific papers. Keyquery-based taxonomy composition can be understood as a two-phase hierarchical document clustering technique that utilizes search queries as cluster labels: In a first phase, the document collection is indexed by a reference search engine, and the documents are tagged with the search queries they are relevant—for their so-called keyqueries. In a second phase, a hierarchical clustering is formed from the keyqueries within an iterative process. We use the explicit topic model ESA as document retrieval model in order to index the CORE dataset in the reference search engine. Under the ESA retrieval model, documents are represented as vectors of similarities to Wikipedia articles; a methodology proven to be advantageous for text categorization tasks. Our paper presents the generated taxonomy and reports on quantitative properties such as document coverage and processing requirements. KW - Massendaten KW - Taxonomie KW - Dynamic Taxonomy Composition, Keyquery, Classification Systems, Reverted Index, Big Data Problem Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170426-31662 ER - TY - JOUR A1 - Völker, Conrad A1 - Mämpel, Silvio A1 - Kornadt, Oliver T1 - Measuring the human body’s micro‐climate using a thermal manikin JF - Indoor Air N2 - The human body is surrounded by a micro‐climate which results from its convective release of heat. In this study, the air temperature and flow velocity of this micro‐climate were measured in a climate chamber at various room temperatures, using a thermal manikin simulating the heat release of the human being. Different techniques (Particle Streak Tracking, thermography, anemometry, and thermistors) were used for measurement and visualization. The manikin surface temperature was adjusted to the particular indoor climate based on simulations with a thermoregulation model (UCBerkeley Thermal Comfort Model). We found that generally, the micro‐climate is thinner at the lower part of the torso, but expands going up. At the head, there is a relatively thick thermal layer, which results in an ascending plume above the head. However, the micro‐climate shape strongly depends not only on the body segment, but also on boundary conditions: the higher the temperature difference between the surface temperature of the manikin and the air temperature, the faster the air flow in the micro‐climate. Finally, convective heat transfer coefficients strongly increase with falling room temperature, while radiative heat transfer coefficients decrease. The type of body segment strongly influences the convective heat transfer coefficient, while only minimally influencing the radiative heat transfer coefficient. KW - Raumklima KW - Mikroklima KW - Wärmeübertragung KW - Strömungsmechanik KW - thermal manikin KW - climate chamber KW - micro climate KW - heat transfer coefficient KW - CFD KW - thermography Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20181025-38153 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/ina.12112 N1 - This is the peer reviewed version of the following article: "Measuring the human body’s micro‐climate using a thermal manikin", which has been published in final form at https://doi.org/10.1111/ina.12112. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. IS - 24, 6 SP - 567 EP - 579 ER - TY - JOUR A1 - Vu-Bac, N. A1 - Lahmer, Tom A1 - Zhang, Yancheng A1 - Zhuang, Xiaoying A1 - Rabczuk, Timon T1 - Stochastic predictions of interfacial characteristic of polymeric nanocomposites (PNCs) JF - Composites Part B Engineering N2 - Stochastic predictions of interfacial characteristic of polymeric nanocomposites (PNCs) KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2014 SP - 80 EP - 95 ER - TY - JOUR A1 - Vu-Bac, N. A1 - Lahmer, Tom A1 - Keitel, Holger A1 - Zhao, Jun-Hua A1 - Zhuang, Xiaoying A1 - Rabczuk, Timon T1 - Stochastic predictions of bulk properties of amorphous polyethylene based on molecular dynamics simulations JF - Mechanics of Materials N2 - Stochastic predictions of bulk properties of amorphous polyethylene based on molecular dynamics simulations KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2014 SP - 70 EP - 84 ER - TY - THES A1 - Udrea, Mihai-Andrei T1 - Assessment of Data from Dynamic Bridge Monitoring N2 - The focus of the thesis is to process measurements acquired from a continuous monitoring system at a railway bridge. Temperature, strain and ambient vibration records are analysed and two main directions of investigation are pursued. The first and the most demanding task is to develop processing routines able to extract modal parameters from ambient vibration measurements. For this purpose, reliable experimental models are achieved on the basis of a stochastic system identification(SSI) procedure. A fully automated algorithm based on a three-stage clustering is implemented to perform a modal parameter estimation for every single measurement. After selecting a baseline of modal parameters, the evolution of eigenfrequencies is studied and correlated to environmental and operational factors. The second aspect deals with the structural response to passing trains. Corresponding triggered records of strain and temperature are processed and their assessment is accomplished using the average strains induced by each train as the reference parameter. Three influences due to speed, temperature and loads are distinguished and treated individually. An attempt to estimate the maximum response variation due to each factor is also carried out. KW - automatic modal analysis KW - stochastic subspace identification KW - modal tracking KW - modal parameter estimation KW - clustering KW - Messtechnik Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20140429-21742 ER - TY - THES A1 - Torrado, Valentina T1 - Die Präsenz des Abjekten in der zeitgenössischen Kunstproduktion N2 - Die Arbeit fokussiert die Rolle des Abjekten in der zeitgenössischen Kunst und hier insbesondere die Rolle der Künstler aus den wohlhabenden – sogenannten postindustriellen – Ländern. Die Arbeit mit abjekten Themen in der Kunstproduktion ist sehr präsent, jedoch aus einer anderen, eher individualistischen Perspektive. Die wichtigsten Orte der Kunst (Galerien, Museen, Kulturzentren) sind Räume der Legitimation dieser Art von Produktion, dabei wird das Potential der Provokation hinterfragt. Die klassische Avantgarde, besonders der Dadaismus, hat das Abjekte zu Beginn des 20. Jahrhunderts als künstlerisches Material genutzt. Das Spiel mit Grenzüberschreitungen durch die Darstellung des Verbotenen und Ekelerregenden machte das Abjekte zur produktiven Kraft auch auf sozialer Ebene, weil es als Mittel dem gesellschaftlichen Protest und der sozialen Kritik diente. KW - Abjekt KW - Ekel KW - Obdachlos Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20140225-21297 ER - TY - JOUR A1 - Thai, Chien H. A1 - Ferreira, A.J.M. A1 - Bordas, Stéphane Pierre Alain A1 - Rabczuk, Timon A1 - Nguyen-Xuan, Hung T1 - Isogeometric analysis of laminated composite and sandwich plates using a new inverse trigonometric shear deformation theory JF - European Journal of Mechanics N2 - Isogeometric analysis of laminated composite and sandwich plates using a new inverse trigonometric shear deformation theory KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 SP - 89 EP - 108 ER - TY - JOUR A1 - Talebi, Hossein A1 - Silani, Mohammad A1 - Bordas, Stéphane Pierre Alain A1 - Kerfriden, Pierre A1 - Rabczuk, Timon T1 - A computational library for multiscale modeling of material failure JF - Computational Mechanics N2 - A computational library for multiscale modeling of material failure KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 ER - TY - JOUR A1 - Silani, Mohammad A1 - Ziaei-Rad, S. A1 - Talebi, Hossein A1 - Rabczuk, Timon T1 - A Semi-Concurrent Multiscale Approach for Modeling Damage in Nanocomposites JF - Theoretical and Applied Fracture Mechanics N2 - A Semi-Concurrent Multiscale Approach for Modeling Damage in Nanocomposites KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 ER - TY - THES A1 - Nowottny, Vera T1 - Die Camera Obscura als Kondensationsmobil : Der Weg von der formalen Ästhetik in der Fotografie bis hin zum künstlerischen Akt des Atmens N2 - Über die formale Ästhetik der Auflösung in der Fotografie bis hin zum künstlerischen Akt des Atmens KW - Camera Obscura KW - Kondensation KW - Kondensation Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20141014-23123 ER - TY - JOUR A1 - Nguyen-Xuan, Hung A1 - Nguyen, Hiep Vinh A1 - Bordas, Stéphane Pierre Alain A1 - Rabczuk, Timon A1 - Duflot, Marc T1 - A cell-based smoothed finite element method for three dimensional solid structures JF - KSCE Journal of Civil Engineering N2 - This paper extends further the strain smoothing technique in finite elements to 8-noded hexahedral elements (CS-FEM-H8). The idea behind the present method is similar to the cell-based smoothed 4-noded quadrilateral finite elements (CS-FEM-Q4). In CSFEM, the smoothing domains are created based on elements, and each element can be further subdivided into 1 or several smoothing cells. It is observed that: 1) The CS-FEM using a single smoothing cell can produce higher stress accuracy, but insufficient rank and poor displacement accuracy; 2) The CS-FEM using several smoothing cells has proper rank, good displacement accuracy, but lower stress accuracy, especially for nearly incompressible and bending dominant problems. We therefore propose 1) an extension of strain smoothing to 8-noded hexahedral elements and 2) an alternative CS-FEM form, which associates the single smoothing cell issue with multi-smoothing cell one via a stabilization technique. Several numerical examples are provided to show the reliability and accuracy of the present formulation. KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 U6 - http://dx.doi.org/10.1007/s12205-012-1515-7 SP - 1230 EP - 1242 ER - TY - JOUR A1 - Nguyen-Thoi, T. A1 - Rabczuk, Timon A1 - Lam-Phat, T. A1 - Ho-Huu, V. A1 - Phung-Van, P. T1 - Free vibration analysis of cracked Mindlin plate using an extended cell-based smoothed discrete shear gap method (XCS-DSG3) JF - Theoretical and Applied Fracture Mechanics N2 - Free vibration analysis of cracked Mindlin plate using an extended cell-based smoothed discrete shear gap method (XCS-DSG3) KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 ER - TY - JOUR A1 - Nguyen-Thanh, Nhon A1 - Muthu, Jacob A1 - Zhuang, Xiaoying A1 - Rabczuk, Timon T1 - An adaptive three-dimensional RHT-splines formulation in linear elasto-statics and elasto-dynamics JF - Computational Mechanics N2 - An adaptive three-dimensional RHT-splines formulation in linear elasto-statics and elasto-dynamics KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 SP - 369 EP - 385 ER - TY - JOUR A1 - Nguyen, V.P. A1 - Kerfriden, Pierre A1 - Bordas, Stéphane Pierre Alain A1 - Rabczuk, Timon T1 - Isogeometric analysis suitable trivariate NURBS representation of composite panels with a new offset algorithm JF - Computer-Aided Design N2 - Isogeometric analysis suitable trivariate NURBS representation of composite panels with a new offset algorithm KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 ER - TY - THES A1 - Nayono, Suwartanti T1 - Development of a Sustainability-based Sanitation Planning Tool (SusTA) for Developing Countries N2 - Background and Research Goal Despite all the efforts in the sanitation sector, it is acknowledged that the world is not on track to meet the MDG sanitation target to reduce the number of people without access to sanitation by 2015. Furthermore, a large number of existing sanitation facilities in developing countries is out of order. This leads to the conclusion that, besides technical failures, the planning process in the sanitation sector was ineffective. This ineffectiveness may be attributed to the lack of knowledge of the sanitation planners about the local conditions of the sanitation project. In addition, sustainability of a technology is often approached from a fragmented perspective that often leads to an unsustainable solution. The dissertation is conducted within the framework of the Integrated Water Resources Management (IWRM) Indonesia project. The goal of this work is to contribute to the development of a methodology of a planning tool for sustainable sanitation technology. The tool is designed for sanitation planners in developing countries, where a top-down planning approach is common practice. The proposed tool enables comprehensive sustainability assessments (using the Helmholtz Concept of Sustainability as reference), taking into account local conditions. State of the Science In the planning practice, many sanitation planning tools focus on technology selection. However, it has become evident that the selection criteria for sustainable technologies are not always considered in the tools’ framework. In other cases, when the criteria are provided by the tool, there is no clear indication of the conditions to be fulfilled in order to meet these criteria. Specifically, there is no reference to what is meant by sustainable technology in a particular context and how to comprehensively assess the sustainability of different technology options. Research Methodology Developing a planning tool is an empirical process, combining theory and practical experience. Hence, the development process of such a tool requires extensive observations, particularly on the interaction between stakeholders in the sanitation sector as well as between technology and its environment. For this purpose, a case study within the project area was carried out. Pucanganom, a village representing common strategic problems in developing countries (e.g. top-down planning approaches, lack of involvement of beneficiaries in the planning process, lack of sustainability assessments) was finally selected as the case study area. After the in-depth case study, an analytical generalisation was developed to enable the tool’s application to a broader context. Results The result of this research is a new tool – the Sustainability-based Sanitation Planning Tool (SusTA). SusTA enables comprehensive sustainability assessment in its five generic steps, namely: (1) analysis of stakeholders and sanitation policy in the region, (2) distance-to-target analysis on sanitation conditions in the region, (3) examination of physical and socio-economic conditions in the project area, (4) contextualisation of the technology assessment process in the project area, and (5) sustainability-oriented technology assessment at the project level. These steps are conducted at two levels of planning – the region and the project area – in order to identify the specific problems and interests which influence the selection of a sanitation system. Each planning step is equipped with tool elements (e.g. set of indicators, household questionnaires, technology assessment matrices) to support the analysis. From the development of SusTA, it can be concluded that four elements are required for an effective and widely applicable sanitation planning tool: sustainability concept, participatory approach, contextualisation framework and modification framework. SusTA provides both a theoretical and a practical basis for assessing the sustainability of sanitation technologies in developing countries. The tool’s main advantages for decision makers in these countries are: It is simple and transparent in its steps, does not require vast amounts of data and does not need a sophisticated computer program. KW - sanitation planning, sustainable technology, sustainability assessment KW - sanitation planning KW - sustainable technology KW - sustainability assessment Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20140619-22227 ER - TY - JOUR A1 - Nanthakumar, S.S. A1 - Lahmer, Tom A1 - Rabczuk, Timon T1 - Detection of multiple flaws in piezoelectric structures using XFEM and level sets JF - Computer Methods in Applied Mechanics and Engineering N2 - Detection of multiple flaws in piezoelectric structures using XFEM and level sets KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2014 SP - 98 EP - 112 ER - TY - JOUR A1 - Nagel, Falk A1 - Simon, Flaviu A1 - Kümmel, Benjamin A1 - Bergmann, Jean Pierre A1 - Hildebrand, Jörg T1 - Optimization Strategies for Laser Welding High Alloy Steel Sheets JF - Physics Procedia N2 - A known phenomenon during laser welding of thin sheets is the deformation caused by thermally induced stresses. This deformation can result in a change of the gap width between the welded parts, which leads to an unstable welding process. Inducing displacements by using a second heat source will compensate for the change in gap width, hence optimizing the welding process. The base material is 1 mm thick austenitic stainless steel 1.4301, which is welded by a CO2 laser. The second heat source is a diode laser. The gap between the welded parts was set between 0.05 mm and 0.1 mm. The influence of the second heat source on the welding process and the welding result is described. The usage of a second heat source allows a higher gap width to be set prior to the welding process. The results of the numerical simulation were found to be corresponding to those of the experiments. KW - Edelstahl KW - Laserschweißen KW - Laser Welding; CO2; Diode; Distortion; Finite Element Analysis; Thermal Analysis; Mechanical Analysis; Numerical Model Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31554 SP - 1242 EP - 1251 ER - TY - JOUR A1 - Motra, Hem Bahadur A1 - Hildebrand, Jörg A1 - Dimmig-Osburg, Andrea T1 - Assessment of strain measurement techniques to characterise mechanical properties of structural steel JF - Engineering Science and Technology, an International Journal N2 - Strain measurement is important in mechanical testing. A wide variety of techniques exists for measuring strain in the tensile test; namely the strain gauge, extensometer, stress and strain determined by machine crosshead motion, Geometric Moire technique, optical strain measurement techniques and others. Each technique has its own advantages and disadvantages. The purpose of this study is to quantitatively compare the strain measurement techniques. To carry out the tensile test experiments for S 235, sixty samples were cut from the web of the I-profile in longitudinal and transverse directions in four different dimensions. The geometry of samples are analysed by 3D scanner and vernier caliper. In addition, the strain values were determined by using strain gauge, extensometer and machine crosshead motion. Three techniques of strain measurement are compared in quantitative manner based on the calculation of mechanical properties (modulus of elasticity, yield strength, tensile strength, percentage elongation at maximum force) of structural steel. A statistical information was used for evaluating the results. It is seen that the extensometer and strain gauge provided reliable data, however the extensometer offers several advantages over the strain gauge and crosshead motion for testing structural steel in tension. Furthermore, estimation of measurement uncertainty is presented for the basic material parameters extracted through strain measurement. KW - Baustahl KW - Werkstoffprüfung KW - Zugversuch KW - Affecting factors; Measurement uncertainty; Materials testing; Quantitative comparison; Strain comparison; Tensile test Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31540 SP - 260 EP - 269 ER - TY - JOUR A1 - Massaretti, Pier Giorgio T1 - Dagli inizi dell’urbanismo teorico alla città moderna. Visioni urbanistiche del totalitarismo – Italia JF - Anthologie zum Städtebau. Das Phänomen Großstadt und die Entstehung der Stadt der Moderne N2 - La prima edizione di questo testo è apparsa, in tedesco, nel volume II.2.: Anthologie zum Städtebau. Das Phänomen Großstadt und die Entstehung der Stadt der Moderne, a cura di Vittorio Magnago Lampugnani, Katia Frey, Eliana Perotti, con il sostegno di Departement Architektur der Eidgenössischen Technischen Hochschule, Zürich (Gebr. Mann Verlag, Berlin 2014, pp. 1307-1390). Previ specifici accordi con l’editore, viene qui presentata la versione originaria, in italiano, dell’intero capitolo: Modernität und Emphase. Städtebau im italienischen Faschismus, e comprendente: i) una capiente saggio introduttivo – in una versione più ampia ed articolata (comprensiva della “Bibliografia sistematica”, di riferimento) del testo in tedesco; ii) la versione in italiano del repertorio antologico di riferimento – e comprensiva di una “Scheda introduttiva”, sull’Autore-Opera, e di una selezione del testo in esame. KW - Städtebau Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170529-32228 SP - 1 EP - 45 ER - TY - CHAP A1 - Massaretti, Pier Giorgio T1 - La ri-fondazione della Libia balbiana (1933-1939). Il poderoso racconto fotografico dei “Ventimila” T2 - Città mediterranee in trasformazione N2 - La prima edizione di questo testo è apparsa negli atti del VI Convegno Internazionale di Studi del CIRICE – Centro Interdipartimentale di Ricerca sull’Iconografia della Città Europea − Università di Napoli Federico II, (Napoli, 13-15 marzo 2014), dal titolo: Città mediterranee in trasformazione. Identità e immagine del paesaggio urbano tra Sette e Novecento, a cura di A. Buccaro e C. de Seta (Collana: Polis, 6; Napoli: Edizioni Scientifiche Italiane, 2014; pp. 1216; ISBN 9788849528145), all’interno della sessione 7, Le trasformazioni del paesaggio urbano nella fotografia e nella cinematografia, coordinatori: F. Capano, M. Iuliano, pp. 1085-1098. Il Convegno, aperto a studiosi di ambito nazionale e internazionale, si poneva l’obiettivo di fare il punto sulla storiografia riguardante la città mediterranea in età contemporanea, con particolare riferimento alla sua identità, struttura e immagine, dall’inizio dell’industrializzazione all’età post-illuminista e borghese, fino ai temi inerenti l’evoluzione/involuzione del territorio e del paesaggio post-industriale, nonché lo sviluppo del modello turistico tra Otto e Novecento. KW - Städtebau Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170529-32234 ER - TY - JOUR A1 - Masood, R. A1 - Kharal, M. K. N. A1 - Nasir, A.R. T1 - Is BIM Adoption Advantageous for Construction Industry of Pakistan? JF - Procedia Engineering N2 - Lack of Information technology applications on construction projects lead to complex flow of data during project life cycle. Building Information Modeling (BIM) has gained attention in the Architectural, Engineering and Construction (AEC) industry, envisage the use of virtual n-dimensional (n-D) models to identify potential conflicts in design, construction or operational of any facility. A questionnaire has been designed to investigate perceptions regarding BIM advantages. Around 102 valid responses received from diversified stakeholders. Results showed very low BIM adoption with low level of ‘Buzz’. BIM is a faster and more effective method for designing and construction management, it improves quality of the design and construction and reduces rework during construction; which came out as the top thee advantages according to the perception of AEC professionals of Pakistan.BIM has least impact on reduction of cost, time and human resources. This research is a bench mark study to understand adoption and advantageous of BIM in Pakistan Construction Industry. KW - Building Information Modeling KW - Bauindustrie KW - Pakistan KW - BIM, BIM Adoption, BIM Advantages , Construction Industry, Pakistan Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31509 SP - 229 EP - 238 ER - TY - CHAP A1 - Marzban, Samira A1 - Almasi, Ashkan A1 - Schwarz, Jochen T1 - REINFORCED CONCRETE STRUCTURAL WALL DATABASE DEVELOPMENT FOR MODEL VALIDATION N2 - Reinforced concrete walls are commonly selected as the lateral resisting systems in seismic design of buildings. The design procedure requires reliable/robust models to predict the wall response. Many researchers, thus, have focused on using the available experimental data to be able to comment on the quality of models at hand. What is missing though is an uncertain attitude towards the experimental data since such data can be affected by different sources of uncertainty. In this paper, we introduce the database created for model quality evaluation purposes considering the uncertainties in the experimental data. This is the first step of a larger study on experience-based model quality evaluation of reinforced concrete walls. Here, we briefly present the database as well as six sample validations of the developed numerical model (the quality of which is to be assessed). The database contains the information on nearly 300 wall specimens from about 50 sources. Both the database and the numerical model, built for uncertainty/sensitivity analysis purposes, are mainly based on ten parameters. These include geometry, material, reinforcement layout and loading properties. The validation results prove that the model is able to predict the wall response satisfactorily. Consequently, the validated numerical model could be used in further quality evaluation studies. KW - Baustoff KW - RC Wall KW - reinforced concrete wall KW - Database Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20150831-24523 ER - TY - THES A1 - Mai, Luu T1 - Structural Control Systems in High-speed Railway Bridges N2 - Structural vibration control of high-speed railway bridges using tuned mass dampers, semi-active tuned mass dampers, fluid viscous dampers and magnetorheological dampers to reduce resonant structural vibrations is studied. In this work, the addressed main issues include modeling of the dynamic interaction of the structures, optimization of the parameters of the dampers and comparison of their efficiency. A new approach to optimize multiple tuned mass damper systems on an uncertain model is proposed based on the H-infinity optimization criteria and the DK iteration procedure with norm-bounded uncertainties in frequency domain. The parameters of tuned mass dampers are optimized directly and simultaneously on different modes contributing significantly to the multi-resonant peaks to explore the different possible combinations of parameters. The effectiveness of the present method is also evaluated through comparison with a previous method. In the case of semi-active tuned mass dampers, an optimization algorithm is derived to control the magnetorheological damper in these semi-active damping systems. The use of the proposed algorithm can generate various combinations of control gains and state variables. This can lead to the improvement of the ability of MR dampers to track the desired control forces. An uncertain model to reduce detuning effects is also considered in this work. Next, for fluid viscous dampers, in order to tune the optimal parameters of fluid viscous dampers to the vicinity of the exact values, analytical formulae which can include structural damping are developed based on the perturbation method. The proposed formulae can also be considered as an improvement of the previous analytical formulae, especially for bridge beams with large structural damping. Finally, a new combination of magnetorheological dampers and a double-beam system to improve the performance of the primary structure vibration is proposed. An algorithm to control magnetorheological dampers in this system is developed by using standard linear matrix inequality techniques. Weight functions as a loop shaping procedure are also introduced in the feedback controllers to improve the tracking ability of magnetorheological damping forces. To this end, the effectiveness of magnetorheological dampers controlled by the proposed scheme, along with the effects of the uncertain and time-delay parameters on the models, are evaluated through numerical simulations. Additionally, a comparison of the dampers based on their performance is also considered in this work. T3 - ISM-Bericht // Institut für Strukturmechanik, Bauhaus-Universität Weimar - 2014,3 KW - High-speed railway bridge KW - Control system KW - Passive damper KW - Semi-active damper KW - Railway bridges Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20141223-23391 SN - 1610-7381 ER - TY - JOUR A1 - Luu, M. A1 - Martinez-Rodrigo, M.D. A1 - Zabel, Volkmar A1 - Könke, Carsten T1 - H∞ optimization of fluid viscous dampers for reducing vibrations of high-speed railway bridges JF - Journal of Sound and Vibration N2 - H∞ optimization of fluid viscous dampers for reducing vibrations of high-speed railway bridges KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 SP - 2421 EP - 2442 ER - TY - JOUR A1 - Linnow, Kirsten A1 - Niermann, Michael A1 - Bonatz, Dennis A1 - Posern, Konrad A1 - Steiger, Michael T1 - Experimental Studies of the Mechanism and Kinetics of Hydration Reactions JF - Energy Procedia N2 - The mechanism and the kinetics of hydration reactions are important for the application of a salt hydrate as a thermochemical heat storage material. MgSO4·H2O and Na2SO4 were chosen in this study because they are both promising candidates for such an application. Considering that the hydration of these salts yields MgSO4·7H2O and Na2SO4·10H2O as the reaction products, the maximum overall heat effect can be calculated from the heat of condensation of water vapor (44 kJ mol–1) and the heats of hydration of 75 kJ·mol-1 (for MgSO4·H2O) and 81 kJ mol-1 (for Na2SO4). Based on the densities of the two hydrated phases, this results in the very high theoretical energy densities of 2.3 GJ·m-3 and 2.4 GJ·m-3, respectively, for MgSO4·7H2O and Na2SO4·10H2O. Not only the energy density is important for the dimensioning of a storage system, but also the kinetics of hydration reactions play a major role for the application as storage material. In the present study, hydration reactions under varying climatic conditions were investigated by using water vapor sorption measurements and in-situ Raman microscopy. Using the phase diagrams, it can be clearly shown that the mechanism and the kinetics depend on the climatic conditions. Below the deliquescence humidity of the lower hydrated phase the hydration proceeds as solid state reaction, whilst above the deliquescence humidity a through solution mechanism takes place. KW - Wärmespeicherung KW - Hydratation KW - Magnesiumsulfat KW - Natriumsulfat KW - hermochemical heat storage, hydration mechanism, magnesium sulfate; sodium sulfate Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31484 SP - 394 EP - 404 ER - TY - JOUR A1 - Le, Ha Thanh A1 - Nguyen, Sang Thanh A1 - Ludwig, Horst-Michael T1 - A Study on High Performance Fine-Grained Concrete Containing Rice Husk Ash JF - International Journal of Concrete Structures and Materials N2 - Rice husk ash (RHA) is classified as a highly reactive pozzolan. It has a very high silica content similar to that of silica fume (SF). Using less-expensive and locally available RHA as a mineral admixture in concrete brings ample benefits to the costs, the technical properties of concrete as well as to the environment. An experimental study of the effect of RHA blending on workability, strength and durability of high performance fine-grained concrete (HPFGC) is presented. The results show that the addition of RHA to HPFGC improved significantly compressive strength, splitting tensile strength and chloride penetration resistance. Interestingly, the ratio of compressive strength to splitting tensile strength of HPFGC was lower than that of ordinary concrete, especially for the concrete made with 20 % RHA. Compressive strength and splitting tensile strength of HPFGC containing RHA was similar and slightly higher, respectively, than for HPFGC containing SF. Chloride penetration resistance of HPFGC containing 10–15 % RHA was comparable with that of HPFGC containing 10 % SF. KW - Hochfester Beton KW - Verarbeitungseigenschaft KW - Druckfestigkeit KW - high performance fine-grained concrete, rice husk ash, workability, compressive strength, splitting tensile strength, chloride penetration resistance Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31477 SP - 301 EP - 307 ER - TY - RPRT A1 - König, Reinhard A1 - Tapias, Estefania A1 - Schmitt, Gerhard T1 - New Methods in Urban Analysis and Simulation: Documentation of the teaching results from the spring semester 2014 N2 - Documentation of the teaching results from the spring semester 2014 at ETH Zurich KW - Städtebau Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20160121-25154 ER - TY - RPRT A1 - König, Reinhard A1 - Tapias, Estefania A1 - König, Gerhard T1 - Digital Urban Simulation: Documentation of the teaching results from the fall semester 2014 N2 - Documentation of the teaching results from the fall semester 2014 KW - Städtebau Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20160121-25125 ER - TY - JOUR A1 - König, Reinhard A1 - Standfest, Matthias A1 - Schmitt, Gerhard ED - Thompson, Emine Mine T1 - Evolutionary multi-criteria optimization for building layout planning: Exemplary application based on the PSSA framework JF - 32nd eCAADe Conference - Volume 2 N2 - When working on urban planning projects there are usually multiple aspects to consider. Often these aspects are contradictory and it is not possible to choose one over the other; instead, they each need to be fulfilled as well as possible. Planners typically draw on past experience when subjectively prioritising which aspects to consider with which degree of importance for their planning concepts. This practice, although understandable, places power and authority in the hands of people who have varying degrees of expertise, which means that the best possible solution is not always found, because it is either not sought or the problem is regarded as being too complex for human capabilities. To improve this situation, the project presented here shows the potential of multi-criteria optimisation algorithms using the example of a new housing layout for an urban block. In addition it is shown, how Self-Organizing-Maps can be used to visualise multi-dimensional solution spaces in an easy analysable and comprehensible form. KW - Architektur Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20160121-25139 UR - http://cumincad.scix.net/cgi-bin/works/Show?_id=ecaade2014_019&sort=DEFAULT&search=series%3aecaade year%3a2014&hits=132 SP - 567 EP - 574 ER - TY - CHAP A1 - König, Reinhard A1 - Schneider, Sven A1 - Hijazi, Ihab Hamzi A1 - Li, Xin A1 - Bielik, Martin A1 - Schmitt, Gerhard A1 - Donath, Dirk T1 - Using geo statistical analysis to detect similarities in emotional responses of urban walkers to urban space T2 - Sixth International Conference on Design Computing and Cognition (DCC14) N2 - Using geo statistical analysis to detect similarities in emotional responses of urban walkers to urban space KW - Städtebau Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20160121-25146 ER - TY - JOUR A1 - König, Reinhard A1 - Knecht, Katja T1 - Comparing two evolutionary algorithm based methods for layout generation: Dense packing versus subdivision JF - Artificial Intelligence for Engineering Design, Analysis and Manufacturing N2 - We present and compare two evolutionary algorithm based methods for rectangular architectural layout generation: dense packing and subdivision algorithms.We analyze the characteristics of the two methods on the basis of three floor plan sce- narios. Our analyses include the speed with which solutions are generated, the reliability with which optimal solutions can be found, and the number of different solutions that can be found overall. In a following step, we discuss the methods with respect to their different user interaction capabilities. In addition, we show that each method has the capability to generate more complex L-shaped layouts. Finally,we conclude that neither of the methods is superior but that each of them is suitable for use in distinct application scenarios because of its different properties. KW - Architektur KW - Informatik KW - Kremlas Y1 - 2014 UR - http://www.journals.cambridge.org/abstract_S0890060414000237 N1 - Paper is only available from the journal home page. SP - 285 EP - 299 ER - TY - GEN A1 - Kleiner, Florian T1 - Charakterisierung des Einflusses der Wärmeleitfähigkeit von Kompositmaterialien auf die thermochemische Wärmespeicherung N2 - Mit dem stetigen Steigen des Anteils an erneuerbaren Energien wird der Einsatz von Speichern immer bedeutsamer. Neben der Speicherung elektrischer Energie ist die Speicherung anfallender solarer bzw. industrieller Wärme eine wichtige Herausforderung. Aufgrund der hohen Energiespeicherdichte kommt dabei der thermochemischen Wärmespeicherung eine entscheidende Rolle zu. Eine Klasse dieser Speichermaterialien bilden Kompositmaterialien, die aus einer offenporigen Matrix und einem darin eingelagerten Salzhydrat bestehen. Ausschlaggebend für eine hohe Speicherdichte ist bei dieser Materialklasse der schnelle Abtransport der durch Wasserdampfsorption entstandenen Wärme. Das entscheidende Kriterium für eine Anwendung als Speichermaterial ist somit die Wärmeleitfähigkeit des Materials. Im Rahmen der Arbeit wurden deshalb die Wärmeleitfähigkeiten ausgewählter Salze (NaCl, MgSO4 und ZnSO4) mit verschiedenen Kristallwassergehalten, Trägermaterialien wie Aktivkohle (Pellets und Pulver) und Zeolitpulver und an den daraus hergestellten Kompositmaterialien untersucht. Ziel war es außerdem Aussagen zu einer günstigen Materialkombination aus offenporigem Trägermaterial und Salzhydrat sowie eines geeigneten Porenfüllgrades zu treffen und Ansätze für die Modellierung der Wärmeleitfähigkeit der Komposite zu liefern. N2 - With the steady increase of renewable energies, the use of storage systems is becoming increasingly important. In addition to the storage of electrical energy, the storage of solar and industrial heat is an important challenge. Due to their high energy storage density, thermochemical heat storage materials are very promising. One class of these storage materials are composit materials, which consist of an porous matrix and an embedded salt hydrate. The decisive factor for a high storage density in this type of materials is the rapid removal of the heat generated by water vapor sorption. The decisive criterion for an application as a storage material is therefore the thermal conductivity of the material. The thermal conductivity of selected salts (NaCl, MgSO4 and ZnSO4) with different crystal water contents, carrier materials such as activated carbon (pellets and powder) and zeolite powder and the resulting composite materials were therefore investigated as part of the work. The aim was also to make statements on a favorable material combination of porous carrier material and salt hydrate as well as a suitable degree of pore filling and to provide approaches for modeling the thermal conductivity of the composites. KW - Wärmespeicher KW - Wärmeleitfähigkeit KW - Werkstoffkunde KW - Wärmespeicher KW - Wärmeleitfähigkeit KW - Hydratsalz KW - thermochemische Wärmespeicherung KW - thermochemical heat storage Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20210921-44968 ER - TY - THES A1 - Kavrakov, Igor T1 - Structural Optimization of Composite Cross-Sections and Elements using Energy Methods N2 - Structural optimization has gained considerable attention in the design of structural engineering structures, especially in the preliminary phase. This study introduces an unconventional approach for structural optimization by utilizing the Energy method with Integral Material Behavior (EIM), based on the Lagrange’s principle of minimum potential energy. An automated two-level optimization search process is proposed, which integrates the EIM, as an alternative method for nonlinear structural analysis, and the bilevel optimization. The proposed procedure secures the equilibrium through minimizing the potential energy on one level, and on a higher level, a design objective function. For this, the most robust strategy of bilevel optimization, the nested method is used. The function of the potential energy is investigated along with its instabilities for physical nonlinear analysis through principle examples, by which the advantages and limitations using this method are reviewed. Furthermore, optimization algorithms are discussed. A numerical fully functional code is developed for nonlinear cross section, element and 2D frame analysis, utilizing different finite elements and is verified against existing EIM programs. As a proof of concept, the method is applied on selected examples using this code on cross section and element level. For the former one a comparison is made with standard procedure, by employing the equilibrium equations within the constrains. The validation of the element level was proven by a theoretical solution of an arch bridge and finally, a truss bridge is optimized. Most of the principle examples are chosen to be adequate for the everyday engineering practice, to demonstrate the effectiveness of the proposed method. This study implies that with further development, this method could become just as competitive as the conventional structural optimization techniques using the Finite Element Method. KW - Strukturoptimierung Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20190815-39593 ER - TY - THES A1 - Kalugila, Shubira T1 - HOUSING INTERVENTIONS AND ITS INFLUENCE ON URBAN DEVELOPMENT: Opportunities and Challenges in Mixed Informal Settlements, in Dar es Salaam - Tanzania N2 - Rapid urbanisation that is not accompanied by socio-economic development strains the capacity of local and national governments to provide even basic services such as shelter. Informal settlements i.e. settlements not built or developed according to the formal regulations have become a solution to many urban dwellers in developing countries. In Tanzania informal settlements accommodate people from low, middle and high income groups. The study explores the nature of potentials and challenges posed by the existence of mixed socio-economic groups in informal settlements, including an assessment of what can be done to optimise utilisation of potentials and mitigation of conflicts. Using a case study strategy, the study was conducted in Dar es Salaam city focusing on Makongo mixed informal settlement. The results show that mixed informal settlements are as a result of several factors including uncoordinated energies of people. The urban development forces that bring change in the development of the city are stronger than the public states capacity to coordinate and manage them. Informal settlements also offer user-friendly land tenure, flexibility in house construction and proximity to livelihoods. Other factors include the nature of socio-economic living patterns and extension of urban boundaries. Community members operate using social norms. Advantages of mixed informal settlements include availability of plots according to needs and affordability while a disadvantage is, people of different socio-economic groups perceive problems differently. For policies to be effective, their formulation should be derived from what is happening on the ground i.e. addressing informal settlements according to their heterogeneity. Moreover, empowered local authorities can assist in implementing national development plans; also actors in land development including government institutions, non-governmental institutions, financial institutions, private sector, professionals, political leaders, research institutions, policy-makers and training institutions need to recognise, understand and respect each other’s roles, and pull resources together to minimise problems related to informality in land development; utilise potentials and minimise challenges in mixed informal settlements in Dar es Salaam. Key words: Informal settlements, land development, urbanisation KW - Informal Settlements KW - Land development KW - Verstädterung KW - Urbanität KW - Urbanisation KW - Landentwicklung Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20140902-22930 ER - TY - JOUR A1 - Joshi, Suraj A1 - Hildebrand, Jörg A1 - Aloraier, Abdulkareem S. A1 - Rabczuk, Timon T1 - Characterization of material properties and heat source parameters in welding simulation of two overlapping beads on a substrate plate JF - Computational Materials Science N2 - This paper presents several aspects of characterization of welding heat source parameters in Goldak’s double ellipsoidal model using Sysweld simulation of welding of two overlapping beads on a substrate steel plate. The overlap percentages ranged from 40% to 80% in increments of 10%. The new material properties of the fused metal were characterized using Weldware and their continuous cooling transformation curves. The convective and radiative heat transfer coefficients as well as the cooling time t8/5 were estimated using numerical formulations from relevant standards. The effects of the simulation geometry and mesh discretization were evaluated in terms of the factor F provided in Sysweld. Eventually, the parameters of Goldak’s double ellipsoidal heat source model were determined for the welding simulation of overlapping beads on the plate and the simulated bead geometry, extent of the molten pool and the HAZ were compared with the macrographs of cross-sections of the experimental weldments. The results showed excellent matching, thus verifying this methodology for determination of welding heat source parameters. KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.commatsci.2012.11.029 SP - 559 EP - 565 ER - TY - JOUR A1 - Jiang, Jin-Wu A1 - Wang, Bing-Shen A1 - Rabczuk, Timon T1 - Phonon modes in single-walled molybdenum disulphide nanotubes: lattice dynamics calculation and molecular dynamics simulation JF - Nanotechnology N2 - Phonon modes in single-walled molybdenum disulphide nanotubes: lattice dynamics calculation and molecular dynamics simulation KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 ER - TY - JOUR A1 - Jiang, Jin-Wu A1 - Park, Harold S. A1 - Rabczuk, Timon T1 - MoS2 nanoresonators: intrinsically better than graphene? JF - Nanoscale N2 - MoS2 nanoresonators: intrinsically better than graphene? KW - Angewandte Mathematik KW - Strukturmechanik Y1 - 2014 SP - 3618 EP - 3625 ER -