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See detailOptimizing algebraic petri net model checking by slicing
Khan, Yasir Imtiaz UL

Report (2013)

Detailed reference viewed: 64 (4 UL)
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See detailThe Node-Based Smoothed Finite Element Method in nonlinear elasticity
Lee, Chang-Kye; Mihai, L. Angela; Bordas, Stéphane UL

Report (2013)

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See detailSpace-time goal-oriented reduced basis approximation for linear wave equation
Hoang, Khac Chi; Kerfriden, Pierre; Bordas, Stéphane UL

Report (2013)

In this paper, we study numerically the linear damped second-order hyperbolic partial differen-tial equation (PDE) with affine parameter dependence using a goal-oriented approach by finite element (FE ... [more ▼]

In this paper, we study numerically the linear damped second-order hyperbolic partial differen-tial equation (PDE) with affine parameter dependence using a goal-oriented approach by finite element (FE) and reduced basis (RB) methods. The main contribution of this paper is the “goal-oriented” proper orthogonal decomposition (POD)–Greedy sampling procedure within the RB approximation context. First, we introduce the RB recipe: Galerkin projection onto a space YN spanned by solutions of the governing PDE at N selected points in parameter space. This set of N parameter points is constructed by the standard POD–Greedy sampling procedure already developed. Second, based on the affine parameter dependence, we make use of the offline-online computational procedures: in the offline stage, we generate the RB space; in the online stage, given a new parameter value, we calculate rapidly and accurately the space-time RB output of interest and its associated asymptotic error. The proposed goal-oriented POD–Greedy sampling procedure can now be implemented and will look for the parameter points such that it minimizes this (asymptotic) output error rather than the solution error (or, error indicator which is the dual norm of residual) as in the standard POD–Greedy procedure. Numerical results show that the new goal-oriented POD–Greedy sampling procedure improves significantly the accuracy of the space-time output computation in comparison with the standard POD–Greedy one. The method is thus ideally suited for repeated, rapid and reliable evaluation of input-output relationships within the space-time setting. [less ▲]

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See detailThe King Edward Point Geodetic Observatory
Teferle, Felix Norman UL

Report (2013)

During the period from 7th until 14th February 2013 Norman Teferle (University of Luxembourg) and Seth White (Unavco Inc.) visited King Edward Point (KEP) research station, South Georgia, to establish the ... [more ▼]

During the period from 7th until 14th February 2013 Norman Teferle (University of Luxembourg) and Seth White (Unavco Inc.) visited King Edward Point (KEP) research station, South Georgia, to establish the KEP Geodetic Observatory (KEPGO). The observatory consists of an autonomous, continuous Global Navigation Satellite System (GNSS) station with auxiliary equipment on Brown Mountain, as well as, benchmarks on Brown Mountain and at KEP research station. The primary objective of the observatory is to measure vertical land movements in order to study sea level changes using the KEP tide gauge record or satellite altimeter data. Therefore, the existing tide gauge was connected to the observatory through precise levelling and campaign GNSS observations. The levelling was carried out over the tide gauge itself, two existing United Kingdom Hydrographic Office (UKHO) and four newly established KEPGO tide gauge benchmarks (TGBMs). The GNSS observations were carried out on two benchmarks and their coordinates were computed with respect to the continuous GNSS station on Brown Mountain. Taking the UKHO height information together with the levelling and GNSS results it is suggested that the UKHO TGBM on the jetty may have settled by a few centimetres over the period from 2003 to 2013 and that the UKHO height datum requires a shift of by about -1 m in order to bring it closer to a globally consistent vertical reference system. This technical report details the installation work and analysis carried out during and after the visit. [less ▲]

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See detailSurvey of Petri nets Slicing
Khan, Yasir Imtiaz UL; Guelfi, Nicolas UL

Report (2013)

Petri nets slicing is a technique that aims to improve the verification of systems modeled in Petri nets. Different Petri nets slicing constructions are studied along with algorithms to compute them ... [more ▼]

Petri nets slicing is a technique that aims to improve the verification of systems modeled in Petri nets. Different Petri nets slicing constructions are studied along with algorithms to compute them. Petri nets slicing was first developed to facilitate debugging but then devel- oped for alleviating the state space explosion problem for model checking Petri nets. This article has twofold objectives, the first is to unify all the existing slicing algorithms syntactically by the definition of a standard abstract syntax and rewriting of the studied slicing algorithms using the proposed syntax. The second is to discuss the contribution of each slicing construction and comparing the major differences between them. One of the interesting exploitation of the survey is for the selection and im- provement of slicing techniques for approaches concerned by optimizing verification of state event models. [less ▲]

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See detailVisual Modelling of and on Tangible User Interfaces
Tobias, Eric; Kelsen, Pierre UL

Report (2012)

The purpose of this thesis is to investigate the use and benefit of visual modelling languages (VMLs) in modelling on tangible user interfaces (TUIs), and modelling TUI applications. Three main research ... [more ▼]

The purpose of this thesis is to investigate the use and benefit of visual modelling languages (VMLs) in modelling on tangible user interfaces (TUIs), and modelling TUI applications. Three main research questions are asked: - Is it possible and practical to model an application or process using a TUI? - Which General-purpose VML (GPVML) performs best in modelling a VML scenario for use on TUI? - Is it realistic to use a GPVML to model complex TUI applications? To answer the first research question, a Business Process Model and Notation, version 2 (BPMN2), ideation scenario is used with a tangible widget toolkit prototype on a TUI table to evaluate the performance and obtain feedback from test candidates. The study showed that it is possible to model a process using a TUI and the test candidate feedback did not lead to the conclusion that the modelling was cumbersome or impractical. To find a suitable GPVML, the thesis explores and evaluates the current state of the art in VMLs for describing general problems. After gathering different VMLs, the thesis compares three languages using a simple scenario: the visual object constraint language (VOCL), augmented constraint diagrams (ACD), and the visual contract language (VCL). A weighted evaluation based on multiple quality criteria led to the conclusion that VCL is best suited to model TUI applications, answering the second research question. The thesis answers the third research question by using VCL to model a more complex and complete scenario of an ideation process, which is based on using a BPMN2 on a TUI. This is done to assess VCL's suitability to more complex problems and its maturity. The study concludes that VCL is not yet mature enough to enable its general applicability in a wide variety of settings. The three research questions were dressed with a hypothesis in mind: collaborative, novice friendly modelling environments are able to reduce the gap between stakeholders and software engineers during software projects, leading to a reduction of unrealistic expectations and an increase in the availability of domain knowledge. While the hypothesis is too broad to be proven by this thesis, the research questions answered here give some insights into how to approach it. [less ▲]

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See detailThe Simple Shear and Simple Tension Problems in Linear and Nonlinear Elasticity
Lee, Chang-Kye; Bordas, Stéphane UL

Report (2012)

Detailed reference viewed: 166 (11 UL)
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See detailNews and stock markets: A survey on abnormal returns and prediction models
Minev, Mihail UL; Schommer, Christoph UL; Grammatikos, Theoharry UL

Report (2012)

Vast amount of news articles are published daily reflecting global topics. The stories represent information about events and expert opinions, which may trigger positive or negative expectations on the ... [more ▼]

Vast amount of news articles are published daily reflecting global topics. The stories represent information about events and expert opinions, which may trigger positive or negative expectations on the stock markets. The literature describes various methods for analyzing such correlations. In this paper we consider related approaches for tracking the impact of news on abnormal stock returns. In the first part we introduce studies with back- ground in Finance. Primarily by applying statistical functions the works examine unusual price volatilities and explore possible sources and market conditions, e.g. biased investors, limited attention, macro-economic variables, country development state, et cetera. In the second part we present studies with background in Computer Science, which take advan- tage of historic news and the equivalent market values. By following the common learning paradigm the projects elaborate prototypes for trend and stock price prediction. In the current survey we evaluate leading approaches regarding the objectives, assumptions, in- put, techniques, and performance. Moreover we provide a comparison framework of the recent prototypes and identify gaps for future research. [less ▲]

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See detailDiversité des jeunes et accès au bien-être (DJAB). Rapport de projet
Berg, Charles UL; Meyer, Jean-Louis; Milmeister, Marianne UL

Report (2012)

L'étude internationale "Health Behaviour in Schoolaged Children (HBSC)" de l'Organisation mondiale de la santé (OMS) a été menée dans les écoles de l'enseignement secondaire (et primaire) luxembourgeois ... [more ▼]

L'étude internationale "Health Behaviour in Schoolaged Children (HBSC)" de l'Organisation mondiale de la santé (OMS) a été menée dans les écoles de l'enseignement secondaire (et primaire) luxembourgeois et un premier rapport en a été publié sous l'intitulé "Das Wohlbefinden der Jugendlichen in Luxemburg". L’échantillon de l’étude comprend uniquement des adolescents scolarisés. Par cette approche, les jeunes en âge scolaire, ne fréquentant pas ou seulement irrégulièrement l’école, sont sous-représentés. Or, afin d’améliorer l’accès au bien-être et à la santé ainsi qu’à l’information y liée, il est important d’identifier les facteurs qui influencent les comportements de santé des jeunes en général et de ceux qui vivent des conditions difficiles en particulier. Par conséquent, il est indispensable d’étudier les jeunes dans la diversité de leurs réalités individuelles, familiales et sociales. Dans un but d’améliorer la représentativité de l’analyse et de faciliter aux professionnels concernés le développement de mesures concrètes de prévention, adaptés aux besoins spécifiques des jeunes, il nous semble important de répliquer l’enquête dans une optique comparative et analytique auprès de groupes de jeunes sous-représentés dans l’étude initiale. Il s’agit notamment de jeunes en situations individuelle, familiale et sociale difficiles et engagés dans des trajectoires vulnérables, comme par exemple des jeunes ayant abandonnés précocement l’école, des toxicomanes ou des jeunes placés dans un centre socio-éducatif. [less ▲]

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See detailA Survey on the Performance of Commercial Mobile Access Networks
Frank, Raphaël UL; Forster, Markus UL; Mario, Gerla et al

Report (2012)

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See detailBypassing the Combinatorial Explosion: Using Similarity to Generate and Prioritize T-wise Test Suites for Large Software Product Lines
Henard, Christopher UL; Papadakis, Mike UL; Perrouin, Gilles UL et al

Report (2012)

Software Product Lines (SPLs) are families of products whose commonalities and variability can be captured by Feature Models (FMs). T-wise testing aims at finding errors triggered by all interactions ... [more ▼]

Software Product Lines (SPLs) are families of products whose commonalities and variability can be captured by Feature Models (FMs). T-wise testing aims at finding errors triggered by all interactions amongst t features, thus reducing drastically the number of products to test. T-wise testing approaches for SPLs are limited to small values of t -- which miss faulty interactions -- or limited by the size of the FM. Furthermore, they neither prioritize the products to test nor provide means to finely control the generation process. This paper offers (a) a search-based approach capable of generating products for large SPLs, forming a scalable and flexible alternative to current techniques and (b) prioritization algorithms for any set of products. Experiments conducted on 124 FMs (including large FMs such as the Linux kernel) demonstrate the feasibility and the practicality of our approach. [less ▲]

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See detailLes langues dans les offres d'emploi du Luxemburger Wort 1984-2009
Pigeron-Piroth, Isabelle UL; Fehlen, Fernand UL

Report (2010)

Cette étude propose une analyse des demandes linguistiques figurant dans les offres d’emploi du Luxemburger Wort sur la période 1984-2009. A partir d’un échantillon de 60 éditions du quotidien national ... [more ▼]

Cette étude propose une analyse des demandes linguistiques figurant dans les offres d’emploi du Luxemburger Wort sur la période 1984-2009. A partir d’un échantillon de 60 éditions du quotidien national, l’étude passe en revue l’évolution des demandes linguistiques, mais aussi des compétences exigées ou souhaitées, et souligne les différences entre les branches d’activité. [less ▲]

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See detailLes retraites au Luxembourg : modélisation et évaluation d'un système diversifié avec répartition et capitalisation
Guigou, Jean-Daniel UL; Lovat, Bruno; Schiltz, Jang UL

Report (2010)

Nous développons un modèle permettant d évaluer l e¢ cacité d un système de pension diversi é - dont le nancement est basé à la fois sur la répartition et la capitalisation - à partir de données propres ... [more ▼]

Nous développons un modèle permettant d évaluer l e¢ cacité d un système de pension diversi é - dont le nancement est basé à la fois sur la répartition et la capitalisation - à partir de données propres au Luxembourg. Le critère d e¢ cacité retenu est celui de la soutenabilité à long terme du système. Nous comparons ainsi la soutenabilité dans le temps d un régime combinant répartition et capitalisation avec celle d un régime reposant uniquement soit sur la répartition, soit sur la capitalisation. Cette étude procède en trois étapes. La première étape consiste à mettre en évidence les courbes d évolution des salaires au Luxembourg. Pour y parvenir, nous avons utilisé une méthode statis- tique récente basée sur les trajectoires de développement. Nous avons estimé les paramètres du modèle à partir d une base de données unique, fournie par l IGSS, comprenant les salaires annualisés de tous les employés du secteur privé luxem- bourgeois. Nous avons ainsi obtenu neuf trajectoires moyennes d évolution des salaires ainsi que le poids de chacune d elles dans la société luxembourgeoise. La deuxième étape propose une évaluation du système d assurance-pension luxembourgeois à partir d un nouveau critère : le coe¢ cient de soutenabilité. Il s agit du nombre d euros que les actifs doivent gagner en moyenne pour assurer chaque euro de retraite avec la législation en vigueur. Nos estimations montrent la forte sensibilité du coe¢ cient de soutenabilité aux variables démographiques, mettant ainsi en évidence le risque qui pèse sur le système par répartition au Luxembourg. La troisième et dernière étape introduit la capitalisation dans l analyse. Concrè- tement, il s agit d une épargne-retraite constituée par annuités constantes et pla- cée à un taux d intérêt aléatoire. Le problème revient alors à déterminer le mon- tant optimal de l annuité pour chacun des neuf groupes d individus déjà identi és et d en déduire les ratios répartition/capitalisation correspondants. Notre critère repose là aussi sur le nombre d euros qu il est nécessaire de gagner pour assurer le nancement de chaque euro de retraite, et de la variabilité de ce nombre, mais en tenant compte cette fois-ci, non seulement de l e¤ort collectif (via la répartition), mais aussi de l e¤ort individuel (via la capitalisation). Le but est alors de contrôler la variabilité de l e¤ort total au sein du nouveau système, sous la contrainte d un gain en soutenabilité par rapport au système initial. Des résultats di¤érents en termes de ratio répartition/capitalisation d une part, et d annuités d autre part, sont obtenus en fonction du gain de soutenabilité que l on se donne a priori. [less ▲]

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See detailEvaluation des Schulversuchs : Jean-Jaurès-Ganztagsschule
Joachim, Patrice UL

Report (2009)

Detailed reference viewed: 52 (6 UL)
See detailNeeds analysis report for Luxembourg in the frame of the EUCIM-TE-project
Berg, Charles UL; Joachim, Patrice UL; Kneip, Nico et al

Report (2009)

Detailed reference viewed: 73 (1 UL)
See detailLearning from life: The role of narrative.
Biesta, Gert UL; Goodson, I.F.; Tedder, M. et al

Report (2008)

Detailed reference viewed: 149 (0 UL)
See detailSynthèse de l'évaluation du Girls' and Boys' Day 2008
Blond-Hanten, Carole; Schumacher, Anette UL

Report (2008)

Detailed reference viewed: 48 (0 UL)
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See detailJoseph Haydns Bearbeitungen Schottischer Volkslieder
Sagrillo, Damien UL

Report (2008)

Detailed reference viewed: 69 (0 UL)
See detailEntwicklung von Standard-Tests zur Überprüfung der Bildungsstandards für Mathematik und Deutsch am Ende der 4. und 8. Schulstufe (Testungen 2006 und 2007)
Frebort, Martina; Khorramdel, Lale; Holocher-Ertl, Stefana et al

Report (2007)

Detailed reference viewed: 61 (0 UL)
See detailTesttheoretische Analyse des Lese-Kompetenztests (8. Schulstufe) gemäß Bildungsstandards (Phase 1: 2006)
Hohensinn, Christine; Reif, Manuel; Gruber, Kathrin et al

Report (2007)

Detailed reference viewed: 56 (0 UL)
See detailTesttheoretische Analyse des Lese-Kompetenztests (8. Schulstufe) gemäß Bildungsstandards (Phase 2:2007)
Gruber, Kathrin; Reif, Manuel; Hohensinn, Christine et al

Report (2007)

Detailed reference viewed: 63 (0 UL)
See detailTesttheoretische Analyse des Lese-Kompetenztests (4. Schulstufe) gemäß Bildungsstandards (Phase 2:2007)
Gruber, Kathrin; Reif, Manuel; Hohensinn, Christine et al

Report (2007)

Detailed reference viewed: 52 (0 UL)
See detailTesttheoretische Analyse des Lese-Kompetenztests (4. Schulstufe) gemäß Bildungsstandards (Phase 1: 2006)
Hohensinn, Christine; Reif, Manuel; Gruber, Kathrin et al

Report (2007)

Detailed reference viewed: 58 (0 UL)
See detailHow is agency possible? Towards an ecological understanding of agency-as-achievement
Biesta, Gert UL; Tedder, M.

Report (2006)

Detailed reference viewed: 913 (28 UL)
See detailGirls' Day 2006. Eine Evaluation
Schumacher, Anette UL; Wagener, Renée UL

Report (2006)

Detailed reference viewed: 67 (1 UL)
See detailLes représentations sociales de la médiation au Luxembourg
Houssemand, Claude UL; Liviero, K

Report (2005)

Detailed reference viewed: 64 (5 UL)
See detailNormen en waarden in de jeugdsport. Een pilot-studie.
Biesta, Gert UL; Stams, G.J.J.M.; Rutten, E. et al

Report (2000)

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See detailIntroduction aux Problèmes Inverses
Francis, Olivier UL

Report (1991)

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See detailA two-dimensional isogeometric boundary element method for linear elastic fracture: a path towards damage tolerance analysis without meshing
Peng, Xuan; Atroshchenko, Elena; Kulasegaram, Sivakumar et al

Report (n.d.)

Detailed reference viewed: 133 (7 UL)
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See detailAn extended finite element method with smooth nodal stress
Peng, Xuan; Kulasegaram, Sivakumar; Bordas, Stéphane UL et al

Report (n.d.)

Detailed reference viewed: 115 (3 UL)