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See detailExperimental tests and numerical modelling on eight slender steel columns under increasing temperatures
Franssen, Jean-Marc ULg; Zhao, Bin; Gernay, Thomas

in Li, G.Q. (Ed.) Proceedings will be delivered at the conference (2014, June)

In order to fill the lack of knowledge about slender elements behavior at elevated temperatures,, a European research project called FIDESC4 has been funded by the RFCS. This project involves experimental ... [more ▼]

In order to fill the lack of knowledge about slender elements behavior at elevated temperatures,, a European research project called FIDESC4 has been funded by the RFCS. This project involves experimental testing, parametric numerical analyses and development of simple design rules. The present paper reports the characteristics and the results of the FIDESC4 experimental test campaign performed at the University of Liege on slender steel columns at elevated temperatures. A total of eight columns have been tested, all of them with I shape section. Six columns were made of welded sections (some prismatic and some tapered members) and two columns were with hot rolled sections. The nominal length of the columns was 3 meters with the whole length being heated. The strength of the material (webs and flanges) was measured on sample before the tests. The order of magnitude of the initial geometrical imperfections was recorded. The columns were not restrained against longitudinal thermal elongation. The supports at the ends were cylindrical thus inducing a restrain against rotation in one plane while allowing rotation in the other plane. The allowed direction of rotation was chosen in each test to induce buckling around the strong or the weak axis. The load was applied at ambient temperature and maintained for a period of 15 minutes after which the temperature was increased under constant load. The load was applied concentrically on some tests and with an eccentricity in other tests. The load eccentricity was either applied at both ends, leading to constant bending moment distribution along the length, or at one end only, leading to a triangular bending moment distribution. Heating was applied by electrical resistances enclosed in ceramic pads. The columns and the ceramic pads were wrapped in ceramic wool insulating material. This technique was preferred to gas heating in a standard test furnace because it allows applying a slower and better controlled heating rate and thus obtaining a more uniform temperature distribution in the member. It is also easier to measured lateral displacements of the column. Preliminary blank tests were performed on unloaded specimen in order to determine the heating range to be used later on the loaded columns. The paper will also report on a modification of the heating technique that was applied and improved significantly the uniformity in the temperature distribution. Numerical simulations were performed before the tests using shell elements of the software SAFIR and assumed values of the material properties in order to predict the failure modes. It was essentially crucial to determine whether lateral supports at intermediate levels should be provided in order to ensure failure in the desired direction. Experience showed that the failure modes developed as predicted by the numerical simulations. Besides a thorough description of the experiments, the paper will also present the obtained results in terms of failure mode, ultimate temperature and evolution of longitudinal and transverse displacement. Some information will also be given about the level of detail that has to be used in the numerical model in order to get accurate results at a reasonable price. [less ▲]

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See detailMicro-plasto-hydrodynamic lubrication: a fundamental mechanism in cold rolling
Laugier, Maxime; Boman, Romain ULg; Legrand, Nicolas et al

in CTMP 2014, 6th International Conference on Tribology in Manufacturing Processes & Joining by Plastic Deformation (2014, June)

Micro Plasto-Hydrodynamic (MPH) lubrication is a general mechanism in metal forming that consists in a re-lubrication of tool-piece solid contacts by an outflow of lubricant from pressurized “pockets” ... [more ▼]

Micro Plasto-Hydrodynamic (MPH) lubrication is a general mechanism in metal forming that consists in a re-lubrication of tool-piece solid contacts by an outflow of lubricant from pressurized “pockets” promoted by the plastic deformation. MPH lubrication is one of the main sources of friction variation (e.g. uncontrolled friction) in metal forming processes like strip drawing or cold rolling. This paper presents experimental results giving evidence of the MPH lubrication mechanism in cold rolling and a new lubrication model that predicts for strip drawing conditions MPH lubrication initiation and lubricant extension along the solid contacts initially in boundary condition. This MPH model could be implemented in a cold rolling model soon to help in high strength steels developments on cold rolling mills. [less ▲]

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See detailComparison of centralized, distributed and hierarchical model predictive control schemes for electromechanical oscillations damping in large-scale power systems
Wang, Da ULg; Glavic, Mevludin ULg; Wehenkel, Louis ULg

in International Journal of Electrical Power & Energy Systems (2014), 58

The paper investigates the feasibility of applying Model Predictive Control (MPC) as a viable strategy to damp wide-area electromechanical oscillations in large-scale power systems. First a fully ... [more ▼]

The paper investigates the feasibility of applying Model Predictive Control (MPC) as a viable strategy to damp wide-area electromechanical oscillations in large-scale power systems. First a fully centralized MPC scheme is considered, and its performances are evaluated first in ideal conditions and then by considering state estimation errors and communication delays. This scheme is further extended into a distributed scheme with the aim of making it more viable for very large-scale or multi-area systems. Finally, a robust hierarchical multi-area MPC scheme is proposed, introducing a second layer of MPC based controllers at the level of individual power plants and transmission lines. Simulations are carried out using a 70-bus test system. The results reveal all three MPC schemes as viable solutions to supplement existing controllers in order to improve the system performance in terms of damping. The hierarchical scheme is the one combining the best performances in nominal conditions and the best robustness with respect to partial component failures and various modeling and measurement errors. [less ▲]

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See detailOn the Quality of BGP Route Collectors for iBGP Policy Inference
Cittadini, Luca; Vissicchio, Stefano; Donnet, Benoît ULg

in IFIP Networking (2014, June)

A significant portion of what is known about Internet routing stems out from public BGP datasets. For this reason, numerous research efforts were devoted to (i) assessing the (in)completeness of the ... [more ▼]

A significant portion of what is known about Internet routing stems out from public BGP datasets. For this reason, numerous research efforts were devoted to (i) assessing the (in)completeness of the datasets, (ii) identifying biases in the dataset, and (iii) augmenting data quality by optimally placing new collectors. However, those studies focused on techniques to extract information about the AS-level Internet topology. In this paper, we show that considering different metrics influences the conclusions about biases and collector placement. Namely, we compare AS-level topology discovery with \iac inference. We find that the same datasets exhibit significantly diverse biases for these two metrics. For example, the sensitivity to the number and position of collectors is noticeably different. Moreover, for both metrics, the marginal utility of adding a new collector is strongly localized with respect to the proximity of the collector. Our results suggest that the ``optimal'' position for new collectors can only be defined with respect to a specific metric, hence posing a fundamental trade-off for maximizing the utility of extensions to the BGP data collection infrastructure. [less ▲]

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See detailOn the Performance of the LISP Beta Network
Coras, Florin; Saucez, Damien; Iannone, Luigi et al

in IFIP Networking (2014, June)

The future Internet has been a hot topic during the past decade and many approaches towards this future Internet, ranging from incremental evolution to complete clean slate ones, have been proposed. One ... [more ▼]

The future Internet has been a hot topic during the past decade and many approaches towards this future Internet, ranging from incremental evolution to complete clean slate ones, have been proposed. One of the proposition, LISP, advocates for the separation of the identifier and the locator roles of IP addresses to reduce BGP churn and BGP table size. Up to now, however, most studies concerning LISP have been theoretical and, in fact, little is known about the actual LISP deployment performance. In this paper, we fill this gap through measurement campaigns carried out on the LISP Beta Network. More precisely, we evaluate the performance of the two key components of the infrastructure: the control plane (i.e., the mapping system) and the interworking mechanism (i.e., communication between LISP and non-LISP sites). Our measurements highlight that performance offered by the LISP interworking infrastructure is strongly dependent on BGP routing policies. If we exclude misconfigured nodes, the mapping system typically provides reliable performance and relatively low median mapping resolution delays. Although the bias is not very important, control plane performance favors USA sites as a result of its larger LISP user base but also because European infrastructure appears to be less reliable. [less ▲]

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See detailLes corps des scientifiques et de l’intellectuel dans la revue La recherche
Dondero, Maria Giulia ULg

in Havelange, Carl (Ed.) La lettre et l'image (2014, June)

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See detailComputational homogenization of cellular materials
Nguyen, Van Dung ULg; Noels, Ludovic ULg

in International Journal of Solids and Structures (2014), 51(11-12), 2183-2203

In this work we propose to study the behavior of cellular materials using a second–order multi–scale computational homogenization approach. During the macroscopic loading, micro-buckling of thin ... [more ▼]

In this work we propose to study the behavior of cellular materials using a second–order multi–scale computational homogenization approach. During the macroscopic loading, micro-buckling of thin components, such as cell walls or cell struts, can occur. Even if the behavior of the materials of which the micro–structure is made remains elliptic, the homogenized behavior can lose its ellipticity. In that case, a localization band is formed and propagates at the macro–scale. When the localization occurs, the assumption of local action in the standard approach, for which the stress state on a material point depends only on the strain state at that point, is no–longer suitable, which motivates the use of the second-order multi–scale computational homogenization scheme. At the macro–scale of this scheme, the discontinuous Galerkin method is chosen to solve the Mindlin strain gradient continuum. At the microscopic scale, the classical finite element resolutions of representative volume elements are considered. Since the meshes generated from cellular materials exhibit voids on the boundaries and are not conforming in general, the periodic boundary conditions are reformulated and are enforced by a polynomial interpolation method. With the presence of instability phenomena at both scales, the arc–length path following technique is adopted to solve both macroscopic and microscopic problems. [less ▲]

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See detailL'Année sartrienne n° 28
Cormann, Grégory ULg

Book published by Groupe d'Etudes Sartriennes (2014)

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See detailLe ciel étoilé d’Isis et d’Héphaïstos à Memphis
Veymiers, Richard ULg

Conference (2014, June)

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See detailThe EU and Brazil in a changing world: strategic partners or competitors?
Santander, Sébastian ULg

in Smith, Michael; Keukeleire, Stephan; Vanhoonacker, Sophie (Eds.) The Diplomatic System of the European Union Evolution, Change and Challenges (2014)

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See detailViBe: A Disruptive Method for Background Subtraction
Van Droogenbroeck, Marc ULg; Barnich, Olivier

in Bouwans; Porikli; Hoferlin (Eds.) et al Background Modeling and Foreground Detection for Video Surveillance (2014)

This chapter presents ViBe and the underlying ideas of the algorithm.

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See detailCHARACTERIZATION OF PROTEINURIA IN DOGUE DE BORDEAUX DOGS USING ELECTROPHORESIS AND URINARY BIOMARKERS
Lavoué, Rachel; Smets, P.; Trumel, Cathy et al

in Proceedings of the 2014 ACVIM Forum (2014, June)

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See detailL’effet d’un dispositif public d’accompagnement et de formation belge sur les trajectoires professionnelles des demandeurs d’emploi
Gérard, Julie ULg

Conference (2014, June)

: Suite aux récents bouleversements économiques et sociaux touchant les pays de l’Union Européenne, de nombreux partenariats entre services publics d’emploi et agences d’emploi privées se sont développés ... [more ▼]

: Suite aux récents bouleversements économiques et sociaux touchant les pays de l’Union Européenne, de nombreux partenariats entre services publics d’emploi et agences d’emploi privées se sont développés et complexifiés, suivant une logique de gestion mixte du marché de l’emploi. Cette communication porte sur l’étude d’un partenariat public-privé entre un service public régional belge et un organisme de formation. À partir des apports conceptuels et théoriques de la sociologie de l’action publique et de la littérature propre aux agences d’emploi privées et aux partenariats public-privé, nous analyserons la capacité d’un dispositif public à assurer la remise à l’emploi de son public-cible. Pour ce faire, nous étudierons son rôle et ses effets sur les trajectoires professionnelles des demandeurs d’emploi y recourant. [less ▲]

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See detailL’effet des dispositifs d’intermédiation sur les trajectoires professionnelles des travailleurs. Le cas d’un bureau de recrutement, recherche et sélection de personnel.
Gérard, Julie ULg

Conference (2014, June)

Au cours de ces dernières années, le souci d’allier flexibilité et sécurité au travail a conduit à l’essor considérable des métiers de l’intermédiation (Orianne et Maroy, 2008). En particulier dans le ... [more ▼]

Au cours de ces dernières années, le souci d’allier flexibilité et sécurité au travail a conduit à l’essor considérable des métiers de l’intermédiation (Orianne et Maroy, 2008). En particulier dans le domaine de l’accompagnement et du développement de carrière, divers dispositifs privés d’aide et de suivi ont vu le jour afin de contribuer à l’amélioration des conditions de travail et d’assister les travailleurs dans leurs transitions professionnelles. Par leur action, ces nouveaux dispositifs n’hésitent pas à complexifier les temporalités sociales en créant de nouvelles opportunités d’emploi et en redéfinissant les rythmes de carrière. À l’aide d’une étude de cas dans le secteur du recrutement belge, nous analyserons la capacité d’un processus de mise en emploi à remplir de tels objectifs dans un contexte de gestion mixte du marché du travail. Approchée d’une manière qualitative (entretiens semi-directifs et observations), nous étudierons l’apport de cette agence de placement au travers d’un cadre théorique qui intègre les concepts de dispositif (Foucault, 1977 ; Peeters et Charlier, 1999 ; Raffnsoe, 2008) et de réseaux sociaux (Grossetti 2005, 2008 et 2011). Nous montrerons qu’un plus de régir l’offre et la demande de travail, ce dispositif d’intermédiation, par son système de cooptation et son accompagnement de carrière, assure la fluidification du marché et sécurise la dynamique des transitions professionnelles. [less ▲]

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See detailSocial Security and Economic Integration
Artige, Lionel ULg; Dedry, Antoine ULg; Pestieau, Pierre ULg

in Economics Letters (2014), 123(June), 318-322

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See detailDe strategische uitdagingen van het EU-Brazilië partnerschap
Santander, Sébastian ULg

in Internationale Spectator (2014)

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See detailNormalizzare il corpo attraverso il cibo. (Micro)pratiche alimentari e inclusione della diversità.
Mescoli, Elsa ULg

Scientific conference (2014, May 29)

Partendo dal presupposto che la costruzione della soggettività individuale sia un processo composito e dinamico, questo intervento mira a metterne in evidenza i sostrati materiali, cioè quei fattori che ... [more ▼]

Partendo dal presupposto che la costruzione della soggettività individuale sia un processo composito e dinamico, questo intervento mira a metterne in evidenza i sostrati materiali, cioè quei fattori che agiscono direttamente sulla corporeità. In particolare, viene considerata la materialità delle pratiche alimentari e culinarie come luogo della definizione stratificata del sé. Tali pratiche dialogano con una pluralità di discorsi che sfumano i confini dei corpi individuali e li rendono permeabili agli effetti delle rappresentazioni collettive e delle appartenenze che queste determinano. L’intervento focalizzerà sulla storia di Bâhirah, una giovane donna di origine marocchina residente nella provincia di Milano. La sue pratiche del quotidiano, indagate con il metodo dell’osservazione partecipante e grazie ad interviste semi-strutturate, forniscono un esempio delle dinamiche enunciate sopra. L’importanza del cibo nella storia di questa donna è determinata da diversi fattori, tra i quali la malattia di una delle sue figlie, affetta da diabete mellito 1. Le disfunzioni corporee che caratterizzano questa patologia, determinano la necessità, da un lato, di un controllo minuzioso degli alimenti ingeriti (dunque incorporati) e degli elementi biologici che li compongono; dall’altro, una excorporazione di alcune funzioni fisiologiche legate all’alimentazione, delegate a strumenti esterni al corpo. Tali azioni sono finalizzate a conformare quest’ultimo ad una “normalità” definita da canoni biomedici, i quali permettono l’inclusione nella collettività “sana”. Il contesto più ampio in cui queste dinamiche si inseriscono, è costituito da una pluralità di discorsi, tra i quali in particolare quelli che riguardano il rapporto tra alimentazione e migrazione. Se da un lato si assiste ad un’ipermobilità delle gastronomie (o dei loro elementi), alla loro delocalizzazione e rilocalizzazione in culture alimentari altre, dall’altro la standardizzazione delle abitudini alimentari proprie alla diversità culturale sembra essere prerogativa essenziale della cosiddetta “integrazione” dei migranti. Tali dinamiche si ripercuotono sulla materialità delle (micro)pratiche quotidiane attorno al corpo che questo intervento si propone di analizzare. Le riflessioni saranno accompagnate da alcuni supporti visivi. [less ▲]

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See detailCorrelation and integration of the Rorschach Comprehensive System and the TCI-R questionnaire
Rentmeister, Daniel; Blavier, Adelaïde ULg; Di Piazza, Laetitia ULg et al

Poster (2014, May 27)

In this study, a dual purpose is sought. First, we statistically compare the Rorschach test interpreted by the Comprehensive System from J.E. Exner and the Temperament and Character Inventory – Revised by ... [more ▼]

In this study, a dual purpose is sought. First, we statistically compare the Rorschach test interpreted by the Comprehensive System from J.E. Exner and the Temperament and Character Inventory – Revised by R. Cloninger to highlight their differences and similarities. Second, through clinical cases, we discuss the relevance of integrating the results obtained by these two tools to establish a comprehensive and consistent psychological profile of an individual. For the statistical comparison, a sample of 27 “healthy” subjects (M = 24.37 years, SD = 2.75) was first submitted to the Rorschach test. Then, immediately after, each subject completed the TCI-R. A correlation analysis (Pearson Rho) was done between various Index and a Bonferroni adjustment was made. For the case studies, 3 subjects were recruited. Anamneses were carried out and the Rorschach test and TCI-R administered. Our first results, which are to be taken with caution because of the small number of subjects in the sample, must be qualified and discussed. From 2448 statistical comparisons, we select the most relevant and discuss different correlation results. The case studies show a concordance in social relationships and impulsivity; and show that the information peculiar to each test allows us to complete the subject’s profile. Finally, it is by addressing two different epistemologies underlying these two tests that we can best explain the psychological differences highlighted in the same individuals. We conclude by suggesting that this difference in results must certainly be understood in an integrative logic and emphasizes the complementarity between these two tests. [less ▲]

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See detailLong protocols to Rorschach Comprehensive System and a posteriori reduction of number of responses: What is the impact on the clinical interpretation ?
Dufour, Cristelle; Englebert, Jérôme ULg

Poster (2014, May 27)

Our study was interested in the exceptionally long protocols, superior to 55 answers, supplied by five subjects in the test of Rorschach according to the method of the Comprehensive System. In order to ... [more ▼]

Our study was interested in the exceptionally long protocols, superior to 55 answers, supplied by five subjects in the test of Rorschach according to the method of the Comprehensive System. In order to gain understanding of which attitude to adopt in front of this kind of protocol, we made a a posteriori reduction of the number of answers by basing us on the recommendations of Exner (Exner, on 2001), then a comparative study between the clinical interpretation realized with all of the answers and with only the first five answers by board. We also replicate this methodology of a posteriori decrease of the number of answers with four answers by board according to the new recommendations of the system R-PAS of Meyer and al. (Meyer and al, on 2009). The sample consists of three raw coal subjects and two psychiatric subjects. Our analysis highlighted a stability of certain variables (EB, Lambda, EA for example) but a difference in the psychological profile of the subjects after reduction. We observed a clarification of the fundamental difficulties to the psychiatric subjects and rather a neutralization of these difficulties for the raw coal subjects, with particularly defence mechanisms which seem more adapted. In our sample, the consideration of all of the answers or only of the partial protocol thus brings a difference in the clinical interpretation ; as a consequence any reduction should be made with big caution. Our study allows to discuss current practices of the test of Rorschach, by looking for a compromise between the inherent constraints to the validity of the test and the questions of the clinical complexity decrease appropriate to any initiative of standardization. [less ▲]

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