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See detailWorkplace Relocation and Mobility Changes in a Transnational Metropolitan Area: The Case of the University of Luxembourg
Sprumont, François UL; Viti, Francesco UL; Caruso, Geoffrey UL et al

in Transportation Research Procedia (2014, December), 4

The aim of this paper is to study the utility variation related to the commuting mobility of University staff members due to their future workplace relocation. During the year 2012, a travel survey was ... [more ▼]

The aim of this paper is to study the utility variation related to the commuting mobility of University staff members due to their future workplace relocation. During the year 2012, a travel survey was completed by a total of 397 staff members, representing 36.4% of the university employees, who filled in a questionnaire which revealed complex decision making patterns due to the special traveling scenario involving four countries at once. A Multinomial Logit model has been used to anticipate the impact of university relocation from the capital city to a developing area in the south of the country which will happen between 2015 and 2018 and that will affect most of the employees. The effects of several Travel Demand Management measures are discussed based on the analysis of alternative scenarios [less ▲]

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See detailAdvances in Applied Mechanics
Bordas, Stéphane UL

Book published by Elsevier (2014)

Advances in Applied Mechanics draws together recent significant advances in various topics in applied mechanics. Published since 1948, Advances in Applied Mechanics aims to provide authoritative review ... [more ▼]

Advances in Applied Mechanics draws together recent significant advances in various topics in applied mechanics. Published since 1948, Advances in Applied Mechanics aims to provide authoritative review articles on topics in the mechanical sciences, primarily of interest to scientists and engineers working in the various branches of mechanics, but also of interest to the many who use the results of investigations in mechanics in various application areas, such as aerospace, chemical, civil, environmental, mechanical and nuclear engineering. [less ▲]

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See detailIsogeometric locking-free plate element: a simple first order shear deformation theory for functionally graded plates
Shuohui, Yin; Hale, Jack UL; Yu, Tiantang et al

in Composite Structures (2014), 118

An effective, simple, robust and locking-free plate formulation is proposed to analyze the static bending, buckling, and free vibration of homogeneous and functionally graded plates. The simple first ... [more ▼]

An effective, simple, robust and locking-free plate formulation is proposed to analyze the static bending, buckling, and free vibration of homogeneous and functionally graded plates. The simple first-order shear deformation theory (S-FSDT), which was recently presented in Thai and Choi (2013) [11], is naturally free from shear-locking and captures the physics of the shear-deformation effect present in the original FSDT, whilst also being less computationally expensive due to having fewer unknowns. The S-FSDT requires C1-continuity that is simple to satisfy with the inherent high-order continuity of the non-uniform rational B-spline (NURBS) basis functions, which we use in the framework of isogeometric analysis (IGA). Numerical examples are solved and the results are compared with reference solutions to confirm the accuracy of the proposed method. Furthermore, the effects of boundary conditions, gradient index, and geometric shape on the mechanical response of functionally graded plates are investigated. [less ▲]

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See detailAssessing partial observability in network sensor location problems
Viti, Francesco UL; Rinaldi, Marco; Francesco, Corman et al

in Transportation Research. Part B : Methodological (2014), 70

The quality of information on a network is crucial for different transportation planning and management applications. Problems focusing on where to strategically extract this information can be broadly ... [more ▼]

The quality of information on a network is crucial for different transportation planning and management applications. Problems focusing on where to strategically extract this information can be broadly subdivided into observability problems, which rely on the topological properties of the network, and flow-estimation problems, where (prior) information on observed flows is needed to identify optimal sensor locations. This paper contributes mainly to the first category: more specifically, it presents a new methodology and an intuitive metric able to quantify the quality of a solution in case of partial observability, i.e. when not all flow variables are observed or can be uniquely determined from the observed flows. This methodology is based on existing approaches that can efficiently find solutions for full observability (i.e., the set of sensors needed to make the system fully determined), and exploits only the algebraic relations between link, route and origin-destination flow variables to quantify the information contained in any arbitrary subset of these variables. The new metric allows, through its adoption within simple search algorithms, to efficiently select sensor locations when the number of available sensors is limited by, for example, budget constraints and is less than the number needed to guarantee full observability. The chosen positions aim at selecting those locations that contain the largest information content on the whole network. This is an important contribution in this field, since even in small sized networks the solution for full observability requires an exceedingly large amount of sensors. The assessment of partial observability solutions, based on explicit route enumeration, allows one to categorize families of full observability solutions, and shows that these contain different information potential. This way, it is possible to rank solutions requiring a lower number of sensors while containing the same information content. We tested this new methodology both on toy networks, in order to analyse the properties of the metric and illustrate its logic, and to explain and test heuristic search algorithms for optimal sensor positioning on a real-sized network. Analysis of partial observability solutions shows that the basic search algorithms succeed in finding the links that contain the largest deal of information in a network. [less ▲]

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See detailGamifying the Commute
McCall, Roderick UL

Presentation (2014, November 14)

The seminar outlined the I-GEAR project which examines the use of gamification to reduce traffic congestion. Topics included user interfaces for gamified applications, requirements capture methodologies ... [more ▼]

The seminar outlined the I-GEAR project which examines the use of gamification to reduce traffic congestion. Topics included user interfaces for gamified applications, requirements capture methodologies and a sample gamified application. [less ▲]

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See detailMultiscale Quasicontinuum Methods for Dissipative Truss Models and Beam Networks
Beex, Lars UL; Peerlings, Ron; Geers, Marc et al

Presentation (2014, November 05)

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See detailCardiff/Luxembourg Computational Mechanics Research Group
Bordas, Stéphane UL; Kerfriden, Pierre; Hale, Jack UL et al

Poster (2014, November)

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See detailDiscrete Multiscale Modelling and Future Research Plans concerning Metals
Beex, Lars UL; Bordas, Stéphane UL; Rappel, Hussein UL et al

Presentation (2014, October 14)

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See detailInteraktive Transitionsforschung und Wissensgenerierung im Bereich nachhaltiges Bauen
JUNG ép. PRELLER, Bérénice UL; Affolderbach, Julia UL; Schulz, Christian UL et al

in PND online (2014), 2014(2), 1-14

Basierend auf den Erfahrungen eines internationalen Forschungsprojekts zu den institutionellen Rahmenbedingungen für Innovativität im nachhaltigen Bauen illustriert der Beitrag das Potenzial interaktiver ... [more ▼]

Basierend auf den Erfahrungen eines internationalen Forschungsprojekts zu den institutionellen Rahmenbedingungen für Innovativität im nachhaltigen Bauen illustriert der Beitrag das Potenzial interaktiver Methoden für die Produktion von »Transitionswissen«. Die frühe Einbindung von lokalen Praktikern, Unternehmern, Wissenschaftlern, politischen Entscheidungsträgern und Vertretern von Nichtregierungsorganisationen dient dabei nicht nur den Forschenden zur Exploration des jeweiligen Forschungskontexts, sondern schafft eine Plattform für produktiven Austausch von Wissen. Methodisch unterstützt durch interaktive Workshops sowie Delphi-basierte Feedback- und Validierungsrunden entsteht über die Projektlaufzeit ein wechselseitiger Lernprozess, der zusätzlich durch den Austausch von Erfahrungen aus vier Fallstudienregionen in Europa, Australien und Kanada inspiriert wird. Er liefert für alle Beteiligten wichtige Erkenntnisse über die Gestaltbarkeit von nachhaltigkeitsorientierten Transitionsprozessen im Baubereich. [less ▲]

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See detailSTUDYING COMMUTER BEHAVIOUR FOR GAMIFYING MOBILITY
Kracheel, Martin UL; McCall, Roderick UL; Koenig, Vincent UL

Presentation (2014, September 30)

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See detailIncentives and gaming environments for changing commuter behaviour
Kracheel, Martin UL; McCall, Roderick UL; Koenig, Vincent UL et al

Scientific Conference (2014, September 30)

The project aims to produce a pervasive, gamified system that tries to incentivize mobility behaviour change by offering alternative activities in contrast to usual journeys in such way that it will ... [more ▼]

The project aims to produce a pervasive, gamified system that tries to incentivize mobility behaviour change by offering alternative activities in contrast to usual journeys in such way that it will reduce traffic, emissions and, in the end, save money. The alternatives, for example, such as taking different modes of transport, are incentivised through gamification. In order to develop this pervasive system, we analysed existing mobility patterns of commuters in Luxembourg. The methodology that we developed consists of a questionnaire, a smartphone application and focus group interviews. This paper presents the findings of the questionnaire and how they influence the design of the gamified pervasive application. [less ▲]

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See detailGeometry-Independent Field approximaTion: CAD-Analysis Integration, geometrical exactness and adaptivity
Xu, Gang; Atroshchenko, Elena; Ma, Weiyin et al

in Computer Methods in Applied Mechanics & Engineering (2014)

In isogeometric analysis (IGA), the same spline representation is employed for both the geometry of the domain and approximation of the unknown fields over this domain. This identity of the geometry and ... [more ▼]

In isogeometric analysis (IGA), the same spline representation is employed for both the geometry of the domain and approximation of the unknown fields over this domain. This identity of the geometry and field approximation spaces was put forward in the now classic 2005 paper [20] as a key advantage on the way to the integration of Computer Aided Design (CAD) and subsequent analysis in Computer Aided Engineering (CAE). [20] claims indeed that any change to the geometry of the domain is automatically inherited by the approximation of the field variables, without requiring the regeneration of the mesh at each change of the domain geometry. Yet, in Finite Element versions of IGA, a parameterization of the interior of the domain must still be constructed, since CAD only provides information about the boundary. The identity of the boundary and field representation decreases the flexibility in which this parameterization can be generated and somewhat constrains the modeling and simulation process, because an approximation able to represent the domain geometry accurately need not be adequate to also approximate the field variables accurately, in particular when the solution is not smooth. We propose here a new paradigm called Geometry-Independent Field approximaTion (GIFT) where the spline spaces used for the geometry and the field variables can be chosen and adapted independently while preserving geometric exactness and tight CAD integration. GIFT has the following features: (1) It is possible to flexibly choose between different spline spaces with different properties to better represent the solution of the problem, e.g. the continuity of the solution field, boundary layers, singularities, whilst retaining geometrical exactness of the domain boundary. (2) For multi-patch analysis, where the domain is composed of several spline patches, the continuity condition between neighboring patches on the solution field can be automatically guaranteed without additional constraints in the variational form. (3) Refinement operations by knot insertion and degree elevation are performed directly on the spline space of the solution field, independently of the spline space of the geometry of the domain, which makes the method versatile. GIFT with PHT-spline solution spaces and NURBS geometries is used to show the effectiveness of the proposed approach. Keywords : Super-parametric methods, Isogeometric analysis (IGA), Geometry-independent Spline Space, PHT-splines, local refinement, adaptivity [less ▲]

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See detailExtension of 2D FEniCS implementation of Cosserat non-local elasticity to the 3D case
Sautot, Camille; Bordas, Stéphane UL; Hale, Jack UL

Report (2014)

The objective of the study is the extension of the existing 2D FEniCS implementation of Cosserat elasticity to the 3D case. The first step is the implementation of a patch-test for a simple problem in ... [more ▼]

The objective of the study is the extension of the existing 2D FEniCS implementation of Cosserat elasticity to the 3D case. The first step is the implementation of a patch-test for a simple problem in classical elasticity as a Timoshenko's beam - this study will show that DOLFIN could offer approximated solutions converging to the analytical solution. The second step is the computation of the stress in a plate with a circular hole. The stress concentration factors around the hole in classical and Cosserat elasticities will be compared, and a convergence study for the Cosserat case will be realised. The third step is the extension to the 3D case with the computation of the stress concentration factor around a spherical cavity in an infinite elastic medium. This computed value will be compare to the analytical solution described by couple-stress theory. [less ▲]

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See detailA Multilayer Software Architecture for Safe Autonomous Robots
Gribov, Vladislav UL; Voos, Holger UL

in Proceedings of 19th IEEE International Conference on Emerging Technologies and Factory Automation, Barcelona, Spain, 16-19 Sept. 2014 (2014, September)

In this paper a safety-oriented model based software architecture for robotic solutions is proposed. The main focus herein is to consider aspects such as real-time, het- erogeneity, deployment, modeling ... [more ▼]

In this paper a safety-oriented model based software architecture for robotic solutions is proposed. The main focus herein is to consider aspects such as real-time, het- erogeneity, deployment, modeling and analysis of emerging effects as well as functional safety and to combine all aspects into an overall development approach. The architecture shall capture the complexity caused by the autonomy and mobility of the robot and support the developer with a suitable chain of evidence especially suited for the safety relevant functions. A use case comprising a lightweight robotic manipulator which will be integrated in a mobile service robot underlines the feasibility of this approach. [less ▲]

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See detailModelling of Fluid-Structure Interaction – Effects of Added Mass, Damping and Stiffness
Zilian, Andreas UL

in Irschik, Hans; Belyaev, Alexander K. (Eds.) Dynamics of Mechanical Systems with Variable Mass (2014)

Fluid-flow around mechanical structures can sometimes lead to catastrophic failures. Improved modelling of fluid/structure interaction is required for safety and mechanical considerations. In this ... [more ▼]

Fluid-flow around mechanical structures can sometimes lead to catastrophic failures. Improved modelling of fluid/structure interaction is required for safety and mechanical considerations. In this contribution, concepts for modelling the interaction of structures and fluids are presented. Starting from excitation mechanisms and associated classifications, various model depth approaches are compared. Among them, the use of added coefficients for quasi-steady problems is discussed. On the basis of potential flow theory, different approaches for determining fluid-induced additional mass are established and illustrated using an analytical example. Given the limitations of simplifying the engineering models, the second part of the paper provides a brief overview on computational methods for fluid-structure interaction and presents a monolithic modelling approach using space-time finite elements for discretisation of both fluid and structure. Applications from aero- and hydro-elasticity show the applicability of computational methods for problems involving flow-induced added mass, damping, and stiffness. [less ▲]

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See detailSustainability Research and Interactive Knowledge Generation
JUNG ép. PRELLER, Bérénice UL; Affolderbach, Julia UL; Schulz, Christian UL et al

E-print/Working paper (2014)

Based on experiences from the GreenRegio research project that investigates framework conditions for innovations in sustainable/green building, this working paper explores the potential of interactive and ... [more ▼]

Based on experiences from the GreenRegio research project that investigates framework conditions for innovations in sustainable/green building, this working paper explores the potential of interactive and collaborative methods for knowledge generation and co-production. Engagement with local practi-tioners, private industry, academics, political decision-makers and representatives of the non-profit sector early on in the research process allows researchers to gain better understanding of the re-search object and context. It also creates a platform for (mutual) knowledge exchange. Methodologi-cally, the project incorporates interactive workshops and Delphi-based feedback and validation rounds, that – over the lifespan of the project – offer a mutual learning process further inspired by in-sights and experiences across four case studies in Europe, Australia, and Canada. The exchange and learning processes provide important insights on different forms and pathways of sustainability transi-tions in the building sector to all participants involved in the project, researchers and researched alike. [less ▲]

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See detailAnalogies to Succeed: Application to a Service Design Problem
Moreno Grandas, Diana Paola UL; Yang, Maria; Blessing, Lucienne UL et al

in Laakso, Miko; Ekman, Kalevi (Eds.) NordDesign 2014 Conference (2014, August)

This study aims to expand current understanding of ideation methods and its transferability from product design domain to service design domain. It applies two Design-by-Analogy (DbA) ideation methods ... [more ▼]

This study aims to expand current understanding of ideation methods and its transferability from product design domain to service design domain. It applies two Design-by-Analogy (DbA) ideation methods (WordTree and SCAMPER) to a real service design problem in an expert participants setting. Quantity and Novelty metric results are analysed along with design fixation effects. Both DbA methods produced statistically significant larger number of novel ideas when compared to the control. The number of novel ideas with SCAMPER method doubled those generated via WordTree. Fixation effects were counterintuitive since SCAMPER appears to be a method that promotes both fixation and de-fixation effects. These findings suggest DbA ideation methods offer positive capabilities for assisting designers to generate solutions for service design problems. [less ▲]

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See detailMeshfree methods for shear-deformable structures based on mixed weak forms
Hale, Jack UL

Scientific Conference (2014, July 24)

Similarly to the finite element method, meshfree methods must be carefully designed to overcome the shear-locking problem when discretising the shear-deformable structural theories. Many successful ... [more ▼]

Similarly to the finite element method, meshfree methods must be carefully designed to overcome the shear-locking problem when discretising the shear-deformable structural theories. Many successful treatments of shear-locking in the finite element literature are constructed through the application of a mixed variational form, where the shear stress is treated as an independent variational quantity in addition to the usual displacements. Because of its sound mathematical underpinnings this is the methodology I have chosen to solve the shear-locking problem when using meshfree basis functions. In this talk I will discuss the mathematical origins of the shear-locking problem and the applicability of the celebrated LBB stability condition for designing well-behaved mixed meshfree approximation schemes. I will show results from two new formulations that demonstrate the effectiveness of this approach. The first method is a meshfree formulation for the Timoshenko beam problem that converges to a classic inf-sup stable finite element method when using Maximum- Entropy basis functions. The second method is a generalised displacement meshfree method for the Reissner- Mindlin problem where the shear stress is eliminated prior to the solution of the linear system using a local patch-projection technique, resulting in a linear system expressed in terms of the original displacement unknowns only. Stability is ensured by using a stabilised weak form which is necessary due to the loss of kernel coercivity for the Reissner-Mindlin problem. [less ▲]

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