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See detailOn the role of enrichment and statistical admissibility of recovered fields in a posteriori error estimation for enriched finite element methods
González-Estrada, O. A.; Ródenas, J. J.; Bordas, Stéphane UL et al

in Engineering Computations (2012), 29(8), 814-841

Purpose - The purpose of this paper is to assess the effect of the statistical admissibility of the recovered solution and the ability of the recovered solution to represent the singular solution; also ... [more ▼]

Purpose - The purpose of this paper is to assess the effect of the statistical admissibility of the recovered solution and the ability of the recovered solution to represent the singular solution; also the accuracy, local and global effectivity of recovery-based error estimators for enriched finite element methods (e.g. the extended finite element method, XFEM). Design/methodology/approach - The authors study the performance of two recovery techniques. The first is a recently developed superconvergent patch recovery procedure with equilibration and enrichment (SPR-CX). The second is known as the extended moving least squares recovery (XMLS), which enriches the recovered solutions but does not enforce equilibrium constraints. Both are extended recovery techniques as the polynomial basis used in the recovery process is enriched with singular terms for a better description of the singular nature of the solution. Findings - Numerical results comparing the convergence and the effectivity index of both techniques with those obtained without the enrichment enhancement clearly show the need for the use of extended recovery techniques in Zienkiewicz-Zhu type error estimators for this class of problems. The results also reveal significant improvements in the effectivities yielded by statistically admissible recovered solutions. Originality/value - The paper shows that both extended recovery procedures and statistical admissibility are key to an accurate assessment of the quality of enriched finite element approximations. © Emerald Group Publishing Limited. [less ▲]

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See detailError estimation and error bounding in quantities of interest based on equilibrated recovered displacement fields
Nadal, E.; González-Estrada, O. A.; Ródenas, J. J. et al

in ECCOMAS 2012 - European Congress on Computational Methods in Applied Sciences and Engineering, e-Book Full Papers (2012)

Over the last ten years there has been an increase on the use of goal-oriented error estimates aimed to quantify the local error on a (non)linear quantity of interest (QoI) that might result relevant for ... [more ▼]

Over the last ten years there has been an increase on the use of goal-oriented error estimates aimed to quantify the local error on a (non)linear quantity of interest (QoI) that might result relevant for design purposes. Residual-based error estimators have been used recursively to obtain upper and lower bounds of the error in quantities of interest for finite element approximations. In this paper, we present a recovery technique for 2D linear elasticity problems, based on the superconvergent patch recovery (SPR), which provides recovered displacement and stress fields that are then utilised to evaluate practical upper and lower error bounds in QoI. [less ▲]

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See detailEquilibrated patch recovery for accurate evaluation of upper error bounds in quantities of interest
González-Estrada, O. A.; Ródenas, J. J.; Nadal, E. et al

in ECCOMAS Thematic Conference - ADMOS 2011: International Conference on Adaptive Modeling and Simulation, An IACM Special Interest Conference (2012)

There is an increasing interest on the use of goal-oriented error estimates which help to measure and control the local error on a linear or non-linear quantity of interest (QoI) that might result ... [more ▼]

There is an increasing interest on the use of goal-oriented error estimates which help to measure and control the local error on a linear or non-linear quantity of interest (QoI) that might result relevant for design purposes (e.g. the mean stress value in a particular area, displacements, the stress intensity factor for fracture problems,⋯). In general, residual-based error estimators have been used to obtain upper and lower bounds of the error in quantities of interest for finite element approximations. In this work, we propose a novel a posteriori recovery technique to obtain an upper error bound of the QoI. We use a recovery procedure based on the superconvergent patch recovery (SPR) technique to obtain nearly statically admissible recovered stress fields for the primal and dual problems. This recovery technique was previously used to obtain upper bounds of the error in energy norm and has been used in this paper to obtain a computable version of the upper bound for the quantity of interest. [less ▲]

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See detailARQ Proxy: Cross-Layer Error Recovery in Wireless Access Networks
Kliazovich, Dzmitry UL; Redana, Simone; Granelli, Fabrizio

in International Journal of Communication Systems (2012), 25(4), 461-477

Wireless networks are being increasingly employed to provide mobile access to network services. In most existing standards, reliable transmission on the wireless medium is achieved through the ... [more ▼]

Wireless networks are being increasingly employed to provide mobile access to network services. In most existing standards, reliable transmission on the wireless medium is achieved through the introduction of ARQ schemes at MAC layer, a strategy which is also employed by TCP for reliable end-to-end data delivery. The paper proposes an approach to overcome the performance degradation deriving from the duplicate ARQ strategies implemented at the transport and MAC layers by introducing a cross-layer solution to reduce unnecessary transmissions on the wireless medium. Furthermore, the paper describes how the proposed scheme, called ARQ Proxy, can be deployed in three different wireless technologies (3G Long-Term Evolution, Wi-Fi, and WiMAX) and provides extensive validation of the achievable improvement through simulations. [less ▲]

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See detailRäume und Identitäten als soziale Praxis. Theorien – Konzepte – Methoden. Tagungsbericht
Binsfeld, Andrea UL; Caregari, Laure UL; Reckinger, Rachel UL et al

E-print/Working paper (2012)

Raum und Identität sind zentrale Kategorien der modernen Sozial- und Kulturwissenschaften. Ihre Prominenz spiegelt sich in den vielfältigen und teilweise auch widersprüchlichen Konzepten der beiden ... [more ▼]

Raum und Identität sind zentrale Kategorien der modernen Sozial- und Kulturwissenschaften. Ihre Prominenz spiegelt sich in den vielfältigen und teilweise auch widersprüchlichen Konzepten der beiden Forschungsfelder wider, ebenso wie in diversen wissenschaftstheoretischen Wenden. Dabei haben sich disziplinenübergreifend konstruktivistische und kontingenzorientierte Auffassungen von Räumen und Identitäten durchgesetzt, die in der sozialen Praxis ihren Kristallisationspunkt finden. [less ▲]

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See detailVertically Splitting a Firm:Promotion and Demotion in a Team Production Experiment
Neugebauer, Tibor UL; LACOMBA, JUAN A.; FATAS, ENRIQUE et al

E-print/Working paper (2012)

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See detailOn the computational complexity of stochastic controller optimization in POMDPs
Vlassis, Nikos UL; Littman, Michael L.; Barber, David

in ACM Transactions on Computation Theory (2012), 4(4), 1-9

We show that the problem of finding an optimal stochastic 'blind' controller in a Markov decision process is an NP-hard problem. The corresponding decision problem is NP-hard, in PSPACE, and SQRT-SUM-hard ... [more ▼]

We show that the problem of finding an optimal stochastic 'blind' controller in a Markov decision process is an NP-hard problem. The corresponding decision problem is NP-hard, in PSPACE, and SQRT-SUM-hard, hence placing it in NP would imply a breakthrough in long-standing open problems in computer science. Our optimization result establishes that the more general problem of stochastic controller optimization in POMDPs is also NP-hard. Nonetheless, we outline a special case that is is convex and admits efficient global solutions. [less ▲]

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See detailLa fonction structurante du dialogue des juges européens pour l'ordre juridique européen
Pelin Raducu, Ioana UL

in Besson, Samantha; Levrat, Nicolas (Eds.) Des-ordres juridiques européens/ (2012)

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See detailExcludability and Contribution: A Laboratory Study in Team Production
Neugebauer, Tibor UL; Fatás; Croson

E-print/Working paper (2012)

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See detailXFEM coupling of granular flows interacting with surrounding fluids
Pasenow, F.; Zilian, Andreas UL; Dinkler, D.

in ECCOMAS 2012 - European Congress on Computational Methods in Applied Sciences and Engineering, e-Book Full Papers (2012)

In this paper, ideas for the simulation of sliding dry granular materials interacting with surrounding fluids are presented and first results are presented. The compressible granular material is modeled ... [more ▼]

In this paper, ideas for the simulation of sliding dry granular materials interacting with surrounding fluids are presented and first results are presented. The compressible granular material is modeled as a medium which can show solid-like and fluid-like characteristics. Therefore a weighted decomposition of stress tensors of a solid-like and a fluid-like phase is applied. The surrounding incompressible fluids are described with a Newtonian constitutive model. Interface dynamics are handled with the level-set method. The model equations are discretized with the space-time finite element method. Discontinuous solution characteristics across interfaces are captured numerically by the extended finite element method (XFEM). For all discontinuities the space of ansatz functions is enriched with Heaviside functions. [less ▲]

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See detailDie Grenzgänger. Eine kulturwissenschaftliche Betrachtung
Wille, Christian UL

in Forum für Politik, Gesellschaft und Kultur in Luxemburg (2012), (315), 16-18

Grenzgänger sind ein populäres Thema in Luxemburg und in der Großregion. Dabei handelt es sich jedoch nicht ausschließlich um grenzüberschreitende Arbeitnehmer, sondern Grenzgänger werden zunehmend auch ... [more ▼]

Grenzgänger sind ein populäres Thema in Luxemburg und in der Großregion. Dabei handelt es sich jedoch nicht ausschließlich um grenzüberschreitende Arbeitnehmer, sondern Grenzgänger werden zunehmend auch als Denkfigur in den modernen Kulturwissenschaften entdeckt. Der Beitrag deckt auf, was einen Grenzgänger ausmacht und weshalb sich der Begriff in seinem Facettenreichtum immer größerer Beliebtheit erfreut. [less ▲]

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See detailRationalitätenvielfalt im Kinderschutz - eine Einführung
Bode, Ingo; Marthaler, Thomas UL; Bastian, Pascal et al

in Marthaler, Thomas; Bastian, Pascal; Bode, Ingo (Eds.) et al Rationalitäten des Kinderschutzes. Kindeswohl und soziale Interventionen aus pluraler Perspektive (2012)

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See detailReal Exchange Rates and Skills
Carpantier, Jean-Francois UL

Scientific Conference (2012)

Detailed reference viewed: 82 (2 UL)
See detailText erhorchen. Marcel Krings versammelt Beiträge zum „Schallarchiv“ der Literatur
Dembeck, Till UL

in www.literaturkritik.de (2012)

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See detailPanorama des relations extérieures de l’Union européenne dans le domaine de l’énergie
Neframi, Eleftheria UL

in Blumann, Claude (Ed.) Vers une politique de l’énergie de l’Union européenne (2012)

Développement de l'action extérieure de l'Union en matière de l'énergie. L'énergie comme objet et comme volet de l'action extérieure de l'Union. L'efficacité de l'action de l'Union en matière de l'énergie ... [more ▼]

Développement de l'action extérieure de l'Union en matière de l'énergie. L'énergie comme objet et comme volet de l'action extérieure de l'Union. L'efficacité de l'action de l'Union en matière de l'énergie. La poursuite des objectifs énergétiques et la compétence externe de l’Union et des Etats membres. Les objectifs énergétiques et la cohérence de l’action extérieure de l’Union. [less ▲]

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See detailAuslandsverluste und ausländisches Steuerrecht: Neuregelung durch das 1. StabG 2012
Haslehner, Werner UL; Kofler, Georg

in Zeitschrift für Gesellschaftsrecht und angrenzendes Steuerrecht (2012), (7), 9-26

Durch das 1. StabG wurde die Hereinnahme von „befreiten“ Betriebsstättenverlusten und von Verlusten ausländischer Gruppenmitglieder mit dem nach ausländischem Steuerrecht ermittelten Verlustbetrag ... [more ▼]

Durch das 1. StabG wurde die Hereinnahme von „befreiten“ Betriebsstättenverlusten und von Verlusten ausländischer Gruppenmitglieder mit dem nach ausländischem Steuerrecht ermittelten Verlustbetrag gedeckelt. Dadurch soll schon auf Ebene der Verlusthereinnahme das Problem der bisherigen unzureichenden Nachversteuerung gelöst werden, das dadurch entstand, dass der hereinzunehmende Verlust zwar nach inländischem Steuerrecht ermittelt wurde, die Nachversteuerung aber auf die Verlustverwertung nach ausländischem Steuerrecht rekurrierte. Die Neuregelung begegnet allerdings systematischen Bedenken und stellt durch seine Bindung an das ausländische Steuerrecht weiterhin einen Fremdkörper im Ertragsteuersystem dar. Nach einer Vorstellung der bisherigen Problemlage und der Neuregelung soll daher in diesem Beitrag der Versuch unternommen werden, als mögliche Alternative zur nunmehrigen Einschränkung der Verlusthereinnahme eine Nachversteuerungssystem zu entwickeln, das durch das ausschließliche Abstellen auf österreichisches Steuerrecht die bisherigen Probleme sachgerecht und systematisch korrekt lösen würde. [less ▲]

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See detailBayesian Reinforcement Learning
Vlassis, Nikos UL; Ghavamzadeh, Mohammad; Mannor, Shie et al

in Wiering, Marco; van Otterlo, Martijn (Eds.) Reinforcement Learning: State of the Art (2012)

This chapter surveys recent lines of work that use Bayesian techniques for reinforcement learning. In Bayesian learning, uncertainty is expressed by a prior distribution over unknown parameters and ... [more ▼]

This chapter surveys recent lines of work that use Bayesian techniques for reinforcement learning. In Bayesian learning, uncertainty is expressed by a prior distribution over unknown parameters and learning is achieved by computing a posterior distribution based on the data observed. Hence, Bayesian reinforcement learning distinguishes itself from other forms of reinforcement learning by explic- itly maintaining a distribution over various quantities such as the parameters of the model, the value function, the policy or its gradient. This yields several benefits: a) domain knowledge can be naturally encoded in the prior distribution to speed up learning; b) the exploration/exploitation tradeoff can be naturally optimized; and c) notions of risk can be naturally taken into account to obtain robust policies. [less ▲]

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See detailSentiment Trades and Option Prices
Lehnert, Thorsten UL; Frijns, Bart; Zwinkels, Remco

E-print/Working paper (2012)

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