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ORBi

In History: David Seymour’s Children of Europe Priem, Karin ; in Allender, Tim; Dussel, Inés; Grosvenor, Ian (Eds.) et al The Visual in Educational History: Reflections on the Practice of History in the Digital Age (n.d.) Detailed reference viewed: 52 (2 UL)The Visual in Educational History: Reflections on the Practice of History in the Digital Age ; ; et al Book published by De Gruyter (n.d.) Detailed reference viewed: 82 (3 UL)Verification of the Quillen conjecture in the rank 2 imaginary quadratic case Rahm, Alexander ; E-print/Working paper (n.d.) We confirm a conjecture of Quillen in the case of the mod 2 cohomology of arithmetic groups SL_2(A[1/2]), where A is an imaginary quadratic ring of integers. To make explicit the free module structure on ... [more ▼] We confirm a conjecture of Quillen in the case of the mod 2 cohomology of arithmetic groups SL_2(A[1/2]), where A is an imaginary quadratic ring of integers. To make explicit the free module structure on the cohomology ring conjectured by Quillen, we compute the mod 2 cohomology of SL_2(Z[sqrt(−2)][1/2]) via the amalgamated decomposition of the latter group. [less ▲] Detailed reference viewed: 78 (1 UL)Safety and feeling of safety in the context of older people ageing at home Lamotte, Mathilde ; Ferring, Dieter ; Tournier, Isabelle in Ageing International (n.d.) Detailed reference viewed: 49 (0 UL)Coupled Molecular Dynamics and Finite Element Method: simulations of kinetics induced by field mediated interaction ; Baroli, Davide ; et al in Physical Review. E ,Statistical, Nonlinear, and Soft Matter Physics (n.d.) A computational approach coupling Molecular Dynamics (MD)-Finite Element Method (FEM) techniques is here proposed for the theoretical study of the dynamics of particles subjected to the electromechanical ... [more ▼] A computational approach coupling Molecular Dynamics (MD)-Finite Element Method (FEM) techniques is here proposed for the theoretical study of the dynamics of particles subjected to the electromechanical forces. The system consists in spherical particles (modeled as micrometric rigid bodies with proper densities and dielectric functions) suspended in a colloidal solution which flows in a microfluidic channel in the presence of a generic non-uniform variable electric field, generated by electrodes. The particles are subjected to external forces (e.g. drag or gravity) which satisfy the particle-like formulation, typical of the MD approach, and to electromechanical force which in turn needs, during the equation of the motion integration, the self-consistent solutions in three dimensions of correct continuum field equation. In the MD-FEM method used in this work, Finite Element Method is applied to solve the continuum field equation and MD technique is applied to the stepwise explicit integration of equation of the motion. Our work shows the potential of coupled MD-FEM for the study of electromechanical particles and opens the double perspective to use a) MD away from the field of the atomistic simulation and b) the continuum/particle approach to another case where the conventional forces’ evaluation method used in MD is not applicable. [less ▲] Detailed reference viewed: 114 (4 UL)A mass conservative Kalman filter algorithm for thermo-computational fluid dynamics ; Baroli, Davide ; et al in Materials (n.d.) Computational fluid-dynamics (CFD) is of wide relevance in engineering and science, due to its capability of simulating the three-dimensional flow at various scales. However, the suitability of a given ... [more ▼] Computational fluid-dynamics (CFD) is of wide relevance in engineering and science, due to its capability of simulating the three-dimensional flow at various scales. However, the suitability of a given model depends on the actual scenarios which are encountered in practice. This challenge of model suitability and calibration could be overcome by a dynamic integration of measured data into the simulation. This paradigm is known as data-driven assimilation (DDA). In this paper, the study is devoted to Kalman filtering, a Bayesian approach, applied to Reynolds-Averaged Navier-Stokes (RANS) equations for turbulent flow. The integration of the Kalman estimator into the PISO segregated scheme was recently investigated by (1). In this work, this approach is extended to the PIMPLE segregated method and to the ther- modynamic analysis of turbulent flow, with the addition of a sub-stepping procedure that ensures mass conservation at each time step and the com- patibility among the unknowns involved. The accuracy of the algorithm is verified with respect to the heated lid-driven cavity benchmark, incorporat- ing also temperature observations, comparing the augmented prediction of the Kalman filter with the CFD solution obtained on a very fine grid. [less ▲] Detailed reference viewed: 139 (7 UL)On the discrete Fuglede and Pompeiu problem Kiss, Gergely ; ; et al E-print/Working paper (n.d.) Detailed reference viewed: 58 (0 UL)Transparency measurement Pierina Brustolin Spagnuelo, Dayana Learning material (n.d.) Detailed reference viewed: 92 (7 UL)Data Integration for Image Guided Deep Brain Stimulation Husch, Andreas Doctoral thesis (n.d.) Detailed reference viewed: 191 (36 UL)The Assessment of Collaborative Problem Solving in PISA 2015: An Investigation of the Validity of the PISA 2015 CPS Tasks. Herborn, Katharina ; Stadler, Matthias ; Mustafic, Maida et al Diverse speeches and writings (n.d.) Detailed reference viewed: 100 (2 UL)Computer-Based Collaborative Problem Solving in PISA 2015 and the Role of the Big Five Herborn, Katharina ; Mustafic, Maida ; Greiff, Samuel Diverse speeches and writings (n.d.) Detailed reference viewed: 103 (10 UL)Collaborative Problem Solving in PISA 2015: Can ComputerAgents Replace Humans? Herborn, Katharina ; Stadler, Matthias ; Mustafic, Maida et al in Computers in Human Behavior (n.d.) Detailed reference viewed: 83 (7 UL)Bayesian inference for the stochastic identification of elastoplastic material parameters: Introduction, misconceptions and insights Rappel, Hussein ; Beex, Lars ; Hale, Jack et al E-print/Working paper (n.d.) We discuss Bayesian inference (BI) for the probabilistic identification of material parameters. This contribution aims to shed light on the use of BI for the identification of elastoplastic material ... [more ▼] We discuss Bayesian inference (BI) for the probabilistic identification of material parameters. This contribution aims to shed light on the use of BI for the identification of elastoplastic material parameters. For this purpose a single spring is considered, for which the stress-strain curves are artificially created. Besides offering a didactic introduction to BI, this paper proposes an approach to incorporate statistical errors both in the measured stresses, and in the measured strains. It is assumed that the uncertainty is only due to measurement errors and the material is homogeneous. Furthermore, a number of possible misconceptions on BI are highlighted based on the purely elastic case. [less ▲] Detailed reference viewed: 381 (106 UL)Accomplishing transparency within the General Data Protection Regulation (Auxiliary material) Pierina Brustolin Spagnuelo, Dayana ; ; Lenzini, Gabriele Learning material (n.d.) Detailed reference viewed: 135 (12 UL)Coarsen Graining: A Renewal Concept of Efficient Adaptivity Techniques for Multiscale Models ; ; et al in Computer Methods in Applied Mechanics and Engineering (n.d.) This paper presents a multiscale method for the quasi-static crack propagation. The coarse region is modeled by the di erential reproducing kernel particle(DRKP) method. The coupling between the coarse ... [more ▼] This paper presents a multiscale method for the quasi-static crack propagation. The coarse region is modeled by the di erential reproducing kernel particle(DRKP) method. The coupling between the coarse scale and ne scale is realized through ghost atoms. The ghost atoms positions are interpolated from the coarse scale solution and enforced as boundary conditions on the ne scale. The ne scale region is adaptively enlarged as the crack propagates and the region behind the crack tip is adaptively coarsened. The centro symmetry parameter(CSP) is used to detect the crack tip location. The triangular lattice corresponds to the lattice structure of the (111) plane of an FCC crystal in the ne scale region. The Lennard-Jones potential is used to model the atom-atom interactions. The method is implemented in two dimensions. The results are compared to pure atomistic simulations and show excellent agreement. [less ▲] Detailed reference viewed: 239 (5 UL)L’atelier du réalisateur ou l’usine à répliques. Citations iconographiques chez Luis Buñuel : Francisco de Goya (et d’autres) dans Belle de jour. Küpper, Achim in Küpper, Achim (Ed.) Luis Buñuel, au-delà du cinéma. (n.d.) Detailed reference viewed: 42 (0 UL)Controlling the Error on Target Motion through Real-time Mesh Adaptation: Applications to Deep Brain Stimulation Bui, Huu Phuoc ; Tomar, Satyendra ; et al E-print/Working paper (n.d.) We present an error-controlled mesh refinement procedure for needle insertion simulation and apply it to the simulation of electrode implantation for deep brain stimulation, including brain shift. Our ... [more ▼] We present an error-controlled mesh refinement procedure for needle insertion simulation and apply it to the simulation of electrode implantation for deep brain stimulation, including brain shift. Our approach enables to control the error in the computation of the displacement and stress fields around the needle tip and needle shaft by suitably refining the mesh, whilst maintaining a coarser mesh in other parts of the domain. We demonstrate through academic and practical examples that our approach increases the accuracy of the displacement and stress fields around the needle without increasing the computational expense. This enables real-time simulations. The proposed methodology has direct implications to increase the accuracy and control the computational expense of the simulation of percutaneous procedures such as biopsy, brachytherapy, regional anesthesia, or cryotherapy and can be essential to the development of robotic guidance. [less ▲] Detailed reference viewed: 635 (34 UL)Minimum energy multiple crack propagation. Part II: Discrete Solution with XFEM. Sutula, Danas ; Bordas, Stéphane in Engineering Fracture Mechanics (n.d.) The three-part paper deals with energy-minimal multiple crack propagation in a linear elastic solid under quasi-static conditions. The principle of minimum total energy, i.e. the sum of the potential and ... [more ▼] The three-part paper deals with energy-minimal multiple crack propagation in a linear elastic solid under quasi-static conditions. The principle of minimum total energy, i.e. the sum of the potential and fracture energies, which stems directly from the Griffith's theory of cracks, is applied to the problem of arbitrary crack growth in 2D. The proposed formulation enables minimisation of the total energy of the mechanical system with respect to the crack extension directions and crack extension lengths to solve for the evolution of the mechanical system over time. The three parts focus, in turn, on (I) the theory of multiple crack growth including competing cracks, (II) the discrete solution by the extended finite element method using the minimum-energy formulation, and (III) the aspects of computer implementation within the Matlab programming language. This Part-II of our three-part paper examines three discrete solution methods for solving fracture mechanics problems based on the principle of minimum total energy. The discrete solution approach is chosen based on the stability property of the fracture configuration at hand. The first method is based on external load-control. It is suitable for stable crack growth and stable fracture configurations. The second method is based on fractured area-control. This method is applicable to stable or unstable fracture growth but it is required that the fracture front be stable. The third solution method is based on a gradient-descent approach. This approach can be applied to arbitrary crack growth problems; however, the gradient-descent formulation cannot be guaranteed to yield the optimal solution in the case of competing crack growth and an unstable fracture front configuration. The main focus is on the gradient-descent solution approach within the framework of the extended finite element discretisation. Although a viable solution method is finally proposed for resolving competing crack growth in the case of an unstable fracture front configuration, the method is not implemented within the present XFEM code but rather exists as a separate proof-of-concept algorithm that is tested against several fabricated benchmark problems. The open-source Matlab code, documentation and example cases are included as supplementary material. [less ▲] Detailed reference viewed: 1946 (142 UL)Minimum energy multiple crack propagation Part I: Theory. Sutula, Danas ; Bordas, Stéphane in Engineering Fracture Mechanics (n.d.) The three-part paper deals with energy-minimal multiple crack propagation in a linear elastic solid under quasi-static conditions. The principle of minimum total energy, i.e. the sum of the potential and ... [more ▼] The three-part paper deals with energy-minimal multiple crack propagation in a linear elastic solid under quasi-static conditions. The principle of minimum total energy, i.e. the sum of the potential and fracture energies, which stems directly from the Griffith's theory of cracks, is applied to the problem of arbitrary crack growth in 2D. The proposed formulation enables minimisation of the total energy of the mechanical system with respect to the crack extension directions and crack extension lengths to solve for the evolution of the mechanical system over time. The three parts focus, in turn, on (I) the theory of multiple crack growth including competing cracks, (II) the discrete solution by the extended finite element method using the minimum-energy formulation, and (III) the aspects of computer implementation within the Matlab programming language. The key contributions of Part-I of this three-part paper are: (1) formulation of the total energy functional governing multiple crack behaviour, (2) three solution methods to the problem of competing crack growth for different fracture front stabilities (e.g. stable, unstable, or a partially stable configuration of crack tips), and (3) the minimum energy criterion for a set of crack tip extensions is posed as the criterion of vanishing rotational dissipation rates with respect to the rotations of the crack extensions. The formulation lends itself to a straightforward application within a discrete framework for determining the crack extension directions of multiple finite-length crack tip increments, which is tackled in Part-II, using the extended finite element method. In Part-III, we discuss various applications and benchmark problems. The open-source Matlab code, documentation, benchmark/example cases are included as supplementary material. [less ▲] Detailed reference viewed: 4123 (205 UL)Minimum energy multiple crack propagation. Part III: XFEM computer implementation and applications. Sutula, Danas ; Bordas, Stéphane in Engineering Fracture Mechanics (n.d.) The three-part paper deals with energy-minimal multiple crack propagation in a linear elastic solid under quasi-static conditions. The principle of minimum total energy, i.e. the sum of the potential and ... [more ▼] The three-part paper deals with energy-minimal multiple crack propagation in a linear elastic solid under quasi-static conditions. The principle of minimum total energy, i.e. the sum of the potential and fracture energies, which stems directly from the Griffith's theory of cracks, is applied to the problem of arbitrary crack growth in 2D. The proposed formulation enables minimisation of the total energy of the mechanical system with respect to the crack extension directions and crack extension lengths to solve for the evolution of the mechanical system over time. The three parts focus, in turn, on (I) the theory of multiple crack growth including competing cracks, (II) the discrete solution by the extended finite element method using the minimum-energy formulation, and (III) the aspects of computer implementation within the Matlab programming language. The key contributions of Part-III of the three-part paper are as follows: (1) implementation of XFEM in Matlab with emphasis on the design of the code to enable fast and efficient computational times of fracture problems involving multiple cracks and arbitrary crack intersections, (2) verification of the minimum energy criterion and comparison with the maximum tension criterion via multiple benchmark studies, and (3) we propose a numerical improvement to the crack growth direction criterion that gives significant improvements in accuracy and convergence rates of the fracture paths, especially on coarse meshes. The comparisons of the fracture paths obtained by the maximum tension (or maximum hoop-stress) criterion and the energy minimisation approach via a multitude of numerical case studies show that both criteria converge to virtually the same fracture solutions albeit from opposite directions. In other words, it is found that the converged fracture path lies in between those obtained by each criterion on coarser meshes. Thus, a modified crack growth direction criterion is proposed that assumes the average direction of the directions obtained by the maximum tension and the minimum energy criteria. The numerical results show significant improvements in accuracy (especially on coarse discretisations) and convergence rates of the fracture paths. Finally, the open-source Matlab code, documentation, benchmarks and example cases are included as supplementary material. [less ▲] Detailed reference viewed: 1843 (128 UL) |
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