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See detailSimulation of a two-slope pyramid made by SPIF using an adaptive remeshing method with solid-shell finite element
Velosa De Sena, José ULg; Guzmán Inostroza, Carlos Felipe ULg; Duchene, Laurent ULg et al

in International Journal of Material Forming (2015)

Single point incremental forming (SPIF) is an emerging application in sheet metal prototyping and small batch production, which enables dieless production of sheet metal parts. This research area has ... [more ▼]

Single point incremental forming (SPIF) is an emerging application in sheet metal prototyping and small batch production, which enables dieless production of sheet metal parts. This research area has grown in the last years, both experimentally and numerically. However, numerical investigations into SPIF process need further improvement to predict the formed shape correctly and faster than current approaches. The current work aims the use of an adaptive remeshing technique, originally developed for shell and later extended to 3D “brick” elements, leading to a Reduced Enhanced Solid-Shell formulation. The CPU time reduction is a demanded request to perform the numerical simulations. A two-slope pyramid shape is used to carry out the numerical simulation and modelling. Its geometric difficulty on the numerical shape prediction and the through thickness stress behaviour are the main analysis targets in the present work. This work confirmed a significant CPU time reduction and an acceptable shape prediction accuracy using an adaptive remeshing method combined with the selected solid-shell element. The stress distribution in thickness direction revealed the occurrence of bending/unbending plus stretching and plastic deformation in regions far from the local deformation in the tool vicinity. [less ▲]

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See detailLa managérialisation de l’administration publique locale en Wallonie Comment l’autorité régionale tente de rationaliser l’action publique locale
Fallon, Catherine ULg

Scientific conference (2015, January 10)

A travers cette contribution, nous développerons une analyse critique des transformations actuelles du recours aux théories et méthodes du management public dans la gestion des politiques, à partir d’une ... [more ▼]

A travers cette contribution, nous développerons une analyse critique des transformations actuelles du recours aux théories et méthodes du management public dans la gestion des politiques, à partir d’une étude des développements récents de l’administration locale en Belgique (Wayenberg et al. 2015). Les autorités locales, politiques et administratives, se voient confrontées à une multiplication des injonctions à une approche stratégique de la gestion publique et aux démarches évaluatives en matière d’analyse politique. Ces outils de rationalisation sont couplés à une extension de la contractualisation de l’administration au niveau des cadres supérieurs. Ces démarches gestionnaires et stratégiques sont diffusées à travers les injonctions réglementaires, les programmes de financement des autorités régionales ainsi que les bureaux de consultants. Elles sont aussi couplées à une extension des processus participatifs, les citoyens étant plus souvent intégrés dans le développement et le pilotage de l’action publique, voire son évaluation. Il s’agit de mettre en évidence les effets réciproques des processus de rationalisation de l’action publique et de sa démocratisation. [less ▲]

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See detailProfession art-thérapeute?
Vandeninden, Elise ULg

Conference (2015, January 09)

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See detailLes mots, la mort, les sorts. Jeanne Favret-Saada
Vangeebergen, Thomas ULg

Learning material (2015)

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See detailManaging the carnivore comeback: assessing the adaptive capacity of the Eurasian lynx (Lynx lynx) to cohabit with humans in shared landscapes
Bouyer, Yaëlle ULg

Doctoral thesis (2015)

Conflicts between humans and large carnivores are one of the most visible examples of the challenges that arise when seeking to achieve coexistence between humans and wildlife. With their large spatial ... [more ▼]

Conflicts between humans and large carnivores are one of the most visible examples of the challenges that arise when seeking to achieve coexistence between humans and wildlife. With their large spatial requirements and predatory behavior, large carnivores are among the most difficult species to preserve in our modern day landscapes. Although large carnivores are usually considered as the epitomes of wilderness, because of human population growth and habitat fragmentation they are inexorably and increasingly faced with the need to live in human-modified landscapes. As a direct consequence, conflicts over depredation on livestock, competition for game species and sometimes over human injury or death will only increase if clear management measures are not taken. This is particularly true in Europe, where, after many decades of absence, large carnivores are recolonizing areas where millions of people are present and where landscapes have been drastically modified. Two approaches to integrating wildlife into a human-dominated world have been proposed at an international scale. The first solution is called land sparing, in which wildlife lives exclusively in protected or wilderness areas where contact between animals and humans will be reduced to the minimum. The second solution, called land sharing, proposes to integrate human activities and wildlife in the same landscapes in non-protected interface zones in what is often called a coexistence approach. In a context of scarce true wilderness areas and a continuum of human-modified habitats, land sharing (i.e. the coexistence approach) is seen as the only possible approach valid for Europe. While a coexistence approach can be readily implemented with smaller species, it can represent a major challenge for species with large space requirements and with predatory behavior. To help manage these species in a long-term conservation vision and to predict where potential conflicts could arise between humans and carnivores, information on large carnivores and their habitat use in anthropogenic landscapes is a pre-requisite. With the return of Eurasian lynx Lynx lynx in Western Europe, the most densely populated areas of the continent_ information on the species tolerance to human land use will help predict where it is likely to occur in anthropogenic landscapes. Data collected in Scandinavia over 15 years were used to assess the use of landscape by lynx. In this study, we explored the effect of anthropogenic and environmental factors on Eurasian lynx habitat use in Scandinavia. The work was developed along two main axes. The first axis aims to explore large scale potential patterns of lynx distribution through transferability of results obtained from habitat modelling to geographically different areas. Transferability of results was tested in two steps. Firstly, transferability success (i.e. predictive ability of the map) was tested at a regional scale using data on roe-deer, the main prey of lynx, to create a map of relative distribution and abundance of prey in southeastern Norway (Chapter 1). Secondly, transferability success was assessed at a larger extent and using data obtained from different sampling method (Chapter 2). A habitat suitability map for Eurasian lynx was produced to be used in management planning in geographically differentiated lynx management zones in Scandinavia. The results indicated that transferability of results from one region to an ecologically different region must be taken with caution. Nevertheless, the habitat suitability maps we constructed on the basis of extrapolation are a valuable asset to help management of the Scandinavian lynx population. The second axis deals with lynx habitat use in relation to anthropogenic and environmental predictors. Lynx tolerance to human presence was first explored by looking at the orientation of home range in the landscape, taking into account proxies of human presence (Chapter 3). Values of these proxies were compared both inside home ranges and within a buffer surrounding the home ranges for several lynx inhabiting an anthropogenic gradient going from near-wilderness to urban periphery. Results showed a high diversity in the extent to which individual lynx are exposed to human influence, indicating that lynx are highly adaptable in terms of living space. Lynx seemed to be able to orientate their home range in order to avoid highest human impacts and select for areas of medium human impacts. Building on these results, finer scale information on lynx habitat use in an anthropogenic landscape were obtained taking into consideration different types of behavior (day-beds, moving and killing) displayed by adult lynx, as well as the effect of cumulative anthropogenic pressures on habitat selection (Chapter 4). Our results showed that lynx select for areas with medium levels of human modification, avoiding both the areas with highest and least modification. Females in general appear to be less tolerant to human modification than males, especially for day-beds. Our study shows that Eurasian lynx can be considered as a species that is adaptable to human- induced changes in landscape even if its motivation to tolerate human presence is clearly linked to the presence and density level of its main prey, the roe deer. Our work shows that, contrary to much of the public and many conservation professionals’ opinions, land sharing with large carnivores in Europe may be possible – even in the immediate proximity to urban centers. However, it is important to bear in mind that these results were obtained from countries with a relatively low human population density; even though some individuals observed lived in the periphery of large cities, the level of habitat fragmentation is less severe than in most of Western Europe. In order to properly assess the capacity of Eurasian lynx to live in highly populated areas, such as the Benelux, more detailed information on lynx distribution from continental European will be needed. However, our results underline the value of combining both correlational and mechanistic studies, and the need for caution in extrapolating data too far from its original context. As large carnivore recovery continues to progress in Europe we may not yet have seen the limits of these species' abilities to adapt. [less ▲]

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See detailImproving the performance of μ-ORC systems
Declaye, Sébastien ULg

Doctoral thesis (2015)

This thesis contributes to the knowledge and the characterization of micro Organic Rankine Cycles (ORC). It is based on experimental data and simulation models. An oil-free scroll expander is tested in a ... [more ▼]

This thesis contributes to the knowledge and the characterization of micro Organic Rankine Cycles (ORC). It is based on experimental data and simulation models. An oil-free scroll expander is tested in a wide range of operating conditions in order to better characterize its performance. Particular attention is paid to the tightness of the machine which is obtained using a magnetic coupling. The measured isentropic efficiency reaches 75% which is higher than typical values reported in the literature. From the experimental results, a performance map of the expander is generated. This performance map can be used to provide fast and accurate calculation of the volumetric and isentropic performance of the expander in a wide range of operating conditions. Five displacement pumps adapted to μ-ORC systems are also tested. These pumps are diaphragm, piston, plunger and gear types. The measured values include the overall efficiency, the volumetric efficiency and the NPSH. A deep analysis of the performance is performed to quantify the losses of each pump, of their electric motor and of their frequency drive. This analysis shows that the weakness of the overall effectiveness (max. 46%) of the pumps tested is mainly due to the low efficiency of the electric motor. A semi-empirical model of the diaphragm pump is proposed and validated based on manufacturer data. This model can predict the mechanical power of the pump and the flow delivered with a good accuracy. The simulation models developed for the expander and the pump are used to simulate a configuration including the pump, the generator and the expander on a single shaft. This configuration aims to avoid the use of a motor and a frequency drive whose performance is poor in the range of power consumed by the pump of a μ-ORC system. The results show a significant increase in the net power produced using the integrated configuration Finally, performance of a prototype of μ-ORC suitable for recovering heat from a two-stage screw compressor are measured and analyzed. The prototype allows generating maximum 3.9% of the electrical power consumed by the compressor. Several optimization options of the prototype are evaluated numerically, showing that the power generation could be increased up to 5.4% of the compressor consumption. These options include using the integrated configuration and optimizing the intercooler boiler design. [less ▲]

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See detailAnalyse de l'actualité fédérale et régionale par le prisme des finances publiques
Piron, Damien ULg

Conference given outside the academic context (2015)

Detailed reference viewed: 28 (2 ULg)
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See detailLes médiateurs scolaires : une ressource pour la gestion des désordres scolaires
Dethier, Baptiste ULg

Conference (2015, January 09)

Dans de nombreux pays, principalement anglo-saxons, la médiation par les pairs s’est développée dans les écoles. Cependant, la spécificité de la Belgique francophone réside dans le développement, par des ... [more ▼]

Dans de nombreux pays, principalement anglo-saxons, la médiation par les pairs s’est développée dans les écoles. Cependant, la spécificité de la Belgique francophone réside dans le développement, par des fonctionnaires publics spécialisés, de dispositifs de médiation scolaire (Kuty et al., 2012). Censés prévenir la violence et le décrochage scolaires et agir sur le climat de l’école, ces dispositifs ne sont pas uniquement destinés à résoudre les problèmes posés par les élèves perturbateurs (ou plutôt de ces élèves en tant que problèmes eux-mêmes) mais aussi à stimuler la participation, l’implication et la responsabilisation des adultes, principalement les enseignants. De ce fait, ils interrogent les formes scolaires traditionnelles, voire bousculent les équilibres historiques du système (Verhoeven, 1997), en ouvrant davantage que des espaces de « traitement » des élèves dits « à problèmes ». Sur base de dix entretiens semi-directifs, cinq focus groups et trois périodes d’observation non participante auprès de médiateurs scolaires belges francophones, cette communication a pour objectif de décrire le cœur du travail de ces derniers pour mieux en saisir les caractéristiques et les enjeux. En effet, à partir d’un cadre légal restreint et flou initié dans les années 1990, les médiateurs ont développé des pratiques et des dispositifs s’inscrivant dans une logique de médiation, organisés sur le principe de l’intervention d’un tiers dit neutre et indépendant visant à aider au rétablissement d’une relation entre deux parties. Ces dispositifs cherchent à rompre avec les logiques historiques de stigmatisation des élèves perturbateurs, que nous interrogerons. [less ▲]

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See detailErosion and sedimentation issues in a hydropower project: assessing impacts and opportunities
Dewals, Benjamin ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Schüttrumpf, Holger (Ed.) Offene Gewässer: Strahlwirkung, Fischaufstieg, Fischabstieg, Sedimente, Schadstoffe (2015, January 09)

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See detailOptimal Enforcement of Competition Policy: The Commitments Procedure under Uncertainty
Gautier, Axel ULg

Scientific conference (2015, January 08)

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See detailSymmetry breaking patterns in 3HDM
Ivanov, Igor ULg; Nishi, Celso

in Journal of High Energy Physics [=JHEP] (2015), 15

An attractive feature of New Physics models with multiple Higgs fields is that they are equipped with discrete symmetry groups in the Higgs and flavour sectors. These symmetry groups are often broken at ... [more ▼]

An attractive feature of New Physics models with multiple Higgs fields is that they are equipped with discrete symmetry groups in the Higgs and flavour sectors. These symmetry groups are often broken at the global minimum of the Higgs potential, either completely or to a proper subgroup, with certain phenomenological consequences. Here, we systematically explore these symmetry breaking patterns in the scalar sector of the three-Higgs-doublet model (3HDM). We use the full list of discrete symmetry groups allowed in 3HDM, and for each group we find all possible ways it can break by the Higgs vacuum expectation value alignment. We also discuss the interplay between these symmetry groups and various forms of CP-violation in the scalar sector of 3HDM. Not only do our results solve the problem for 3HDM, but they also hint at several general features in multi-scalar sectors. [less ▲]

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See detailQualité diagnostique et efficacité d'un système en ligne entrainant à la résolution de problèmes complexes en physique
Marique, Pierre-Xavier ULg; Jacquet, Maud ULg; Georges, François ULg et al

Conference (2015, January 08)

Dans le cadre de projets de lutte contre l’échec en bachelier, le LabSET et des enseignants de physique de l'Université de Liège ont développé un dispositif en ligne d’entraînement à la résolution de ... [more ▼]

Dans le cadre de projets de lutte contre l’échec en bachelier, le LabSET et des enseignants de physique de l'Université de Liège ont développé un dispositif en ligne d’entraînement à la résolution de problèmes complexes en physique. La recherche porte d’une part sur le diagnostic de la maîtrise des processus cognitifs à mobiliser pour résoudre des problèmes de physique et d’autre part sur le lien entre l’entrainement effectif en ligne et la performance des étudiants lors de la résolution de problèmes à l'examen. Les analyses reposent sur étude menée auprès de 876 étudiants inscrits en premier bachelier médecine. Elles ont été effectuées sur bases des données subjectives (auto-évaluation du processus et du produit) et objectives (nombre de connexions aux exercices en ligne, résultats de maîtrise des questions spécifiques aux processus cognitifs étudiés, taux de réussite et notes aux examens). A l’issue de la recherche, nous constatons que c’est le processus d’analyse. Près de 50 % des étudiants en sont conscients. Bien que la force d'association soit de faible à moyenne, une dépendance est observée entre travail en ligne et réussite aux problèmes présentés à l’examen de juin. Les notes des étudiants ayant travaillé en ligne sont supérieures à celles des étudiants n’ayant réalisé aucun problème en ligne. Cependant, étant donné que les étudiants ayant réussi la physique sont aussi ceux ayant réussi des autres matières scientifiques, il est difficile d'établir un rapport de causalité entre travail en ligne et performances. [less ▲]

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See detailQuelle voiture pour demain? Existence des solutions alternatives et évolution nécessaire des systèmes de transport collectifs et individuels
Duysinx, Pierre ULg

Scientific conference (2015, January 08)

Face aux défis du 21ème siècle, il est légitime de s’interroger sur l’existence et l’évolution nécessaire des systèmes de transports collectifs et individuels. L’exposé présente les lignes de forces qui ... [more ▼]

Face aux défis du 21ème siècle, il est légitime de s’interroger sur l’existence et l’évolution nécessaire des systèmes de transports collectifs et individuels. L’exposé présente les lignes de forces qui guident l’évolution des véhicules afin de les rendre plus soutenables : écologiques, économiques et socialement acceptables à l’horizon 2030-2050. [less ▲]

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See detailLa réforme des soins de santé mentale en Belgique: pas complètement convergents, mais concrètement interdépendants
Thunus, Sophie ULg

Conference (2015, January 08)

Dans cet article, nous retracerons d’abord les grandes lignes des évolutions des associations d’usagers et de proches en santé mentale, en Europe et en Belgique. Ensuite, nous présenterons une ... [more ▼]

Dans cet article, nous retracerons d’abord les grandes lignes des évolutions des associations d’usagers et de proches en santé mentale, en Europe et en Belgique. Ensuite, nous présenterons une expérimentation politique dans le champ de la santé mentale en Belgique, qui a été l’occasion, pour les associations d’usagers et de proches, d’institutionnaliser leur participation. A cette occasion, nous évoquerons les motifs politiques à l’origine du projet de participation (acte 1) confié par les autorités publiques belges aux associations, ses modalités, et son implémentation au sein d’un dispositif d’action publique impliquant également des experts professionnels et scientifiques. Dans un troisième temps, nous nous intéresserons à la poursuite du projet participation dans le cadre de la réforme actuelle de la santé mentale et de la psychiatrie. Nous décrirons les modalités d’implémentation du projet (acte 2) et les nouveaux défis qui se posent aux associations, au fur-et-à-mesure de l’augmentation et de la visibilité accrue de leur participation aux niveaux institutionnels et politiques. En conclusion, nous soulignerons le caractère contingent de l’émergence et de la stabilisation de la participation en Belgique. Nous verrons que ce caractère contingent est à l’origine de fortes interdépendances entre le développement de la participation, des projets politiques spécifiques et trajectoires individuelles particulières. Cette interdépendance génère à son tour des enjeux spécifiques, pour les associations et les représentants des usagers, en termes identitaires et de légitimité. Nous soulignerons en outre le caractère incrémental du processus par lequel les associations stabilisent leur discours, leur méthodologie et leur intervention concrète dans la prise de décision aux niveaux macro et micro. A cet égard, mettrons en évidence l’importance de la production continue de documents (recommandations, questionnaires, …) stabilisant les éléments-clé de ce discours et permettant aux experts par le vécu de le porter en différents endroits, au sein des institutions des soins et dans la sphère politique. Finalement, nous envisagerons l’hypothèse de la professionnalisation des représentant(e)s des associations et des représentants des usagers, tout en soulignant les enjeux personnels et structurels associés à cette professionnalisation. [less ▲]

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See detailInvariant games and non-homogeneous Beatty sequences
Rigo, Michel ULg

Scientific conference (2015, January 08)

The aim of this talk is to introduce some notions arising in combinatorial game theory and make the connection with combinatorics on words. We characterize all pairs of complementary non-homogenous Beatty ... [more ▼]

The aim of this talk is to introduce some notions arising in combinatorial game theory and make the connection with combinatorics on words. We characterize all pairs of complementary non-homogenous Beatty sequences (A_n)n≥0 and (B_n)n≥0 for which there exists an invariant game having exactly {(A_n,B_n)∣n≥0}∪{(B_n,A_n)∣n≥0} as set of P-positions. Using the notion of Sturmian word and tools arising in symbolic dynamics and combinatorics on words, this characterization can be translated to a decision procedure relying only on a few algebraic tests about algebraicity or rational independence. Given any four real numbers defining the two sequences, up to these tests, we can therefore decide whether or not such an invariant game exists. [less ▲]

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See detailAutour du sujet défait
Vrancken, Didier ULg

Conference (2015, January 07)

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See detailRecent summer Arctic atmospheric circulation anomalies in a historical perspective
Belleflamme, Alexandre ULg; Fettweis, Xavier ULg; Erpicum, Michel ULg

in Cryosphere (The) (2015), 9

A significant increase in the summertime occurrence of a high pressure area over the Beaufort Sea, the Canadian Arctic Archipelago, and Greenland has been observed since the beginning of the 2000s, and ... [more ▼]

A significant increase in the summertime occurrence of a high pressure area over the Beaufort Sea, the Canadian Arctic Archipelago, and Greenland has been observed since the beginning of the 2000s, and particularly between 2007 and 2012. These circulation anomalies are likely partly responsible for the enhanced Greenland ice sheet melt as well as the Arctic sea ice loss observed since 2007. Therefore, it is interesting to analyse whether similar conditions might have happened since the late 19th century over the Arctic region. We have used an atmospheric circulation type classification based on daily mean sea level pressure and 500 hPa geopotential height data from five reanalysis data sets (ERA-Interim, ERA-40, NCEP/NCAR, ERA-20C, and 20CRv2) to put the recent circulation anomalies in perspective with the atmospheric circulation variability since 1871. We found that circulation conditions similar to 2007–2012 have occurred in the past, despite a higher uncertainty of the reconstructed circulation before 1940. For example, only ERA-20C shows circulation anomalies that could explain the 1920–1930 summertime Greenland warming, in contrast to 20CRv2. While the recent anomalies exceed by a factor of 2 the interannual variability of the atmospheric circulation of the Arctic region, their origin (natural variability or global warming) remains debatable. [less ▲]

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See detailContributions to combinatorics on words in an abelian context and covering problems in graphs
Vandomme, Elise ULg

Doctoral thesis (2015)

This thesis dissertation is divided into two (distinct but connected) parts that reflect the joint PhD. We study and we solve several questions regarding on the one hand combinatorics on words in an ... [more ▼]

This thesis dissertation is divided into two (distinct but connected) parts that reflect the joint PhD. We study and we solve several questions regarding on the one hand combinatorics on words in an abelian context and on the other hand covering problems in graphs. Each particular problem is the topic of a chapter. In combinatorics on words, the first problem considered focuses on the 2-regularity of sequences in the sense of Allouche and Shallit. We prove that a sequence satisfying a certain symmetry property is 2-regular. Then we apply this theorem to show that the 2-abelian complexity functions of the Thue--Morse word and the period-doubling word are 2-regular. The computation and arguments leading to these results fit into a quite general scheme that we hope can be used again to prove additional regularity results. The second question concerns the notion of return words up to abelian equivalence, introduced by Puzynina and Zamboni. We obtain a characterization of Sturmian words with non-zero intercept in terms of the finiteness of the set of abelian return words to all prefixes. We describe this set of abelian returns for the Fibonacci word but also for the Thue--Morse word (which is not Sturmian). We investigate the relationship existing between the abelian complexity and the finiteness of this set. In graph theory, the first problem considered deals with identifying codes in graphs. These codes were introduced by Karpovsky, Chakrabarty and Levitin to model fault-diagnosis in multiprocessor systems. The ratio between the optimal size of an identifying code and the optimal size of a fractional relaxation of an identifying code is between 1 and 2 ln(|V|)+1 where V is the vertex set of the graph. We focus on vertex-transitive graphs, since we can compute the exact fractional solution for them. We exhibit infinite families, called generalized quadrangles, of vertex-transitive graphs with integer and fractional identifying codes of order |V|^a with a in {1/4,1/3,2/5}. The second problem concerns (r,a,b)-covering codes of the infinite grid already studied by Axenovich and Puzynina. We introduce the notion of constant 2-labellings of weighted graphs and study them in four particular weighted cycles. We present a method to link these labellings with covering codes. Finally, we determine the precise values of the constants a and b of any (r,a,b)-covering code of the infinite grid with |a-b|>4. This is an extension of a theorem of Axenovich. [less ▲]

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