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See detailRecyclage des briques cassées pour améliorer les propriétés céramiques des argiles plastiques (Meknès, Maroc)
El Ouahabi, Meriam ULg; Daoudi, Lahcen; El Boudour El Idrissi, Hicham ULg et al

Poster (2014, October 27)

Dans le Bassin de Saïs (nord ouest du Maroc), les argiles du Miocène de la région de Meknès sont utilisées dans l’industrie céramique locale pour la fabrication des briques. Ces argiles riches en smectite ... [more ▼]

Dans le Bassin de Saïs (nord ouest du Maroc), les argiles du Miocène de la région de Meknès sont utilisées dans l’industrie céramique locale pour la fabrication des briques. Ces argiles riches en smectite et en carbonates, ont une granulométrie très fine, marquée par la quasi absence de la fraction sableuse. Ces propriétés les rendent très plastiques, ce qui engendre des taux de retrait importants au séchage et à la cuisson et des problèmes de qualité du produit fini qui s’en suivent (fissurations, déformations et casses pendant les processus de séchage et de cuisson). Dans le but de palier à ce problème et d’améliorer la qualité du produit fini, nous proposons au cours de cette étude de recycler les déchets de briques cassées. Afin d'atteindre ces objectifs, 4 formulations ont été réalisées à base d’argiles plastiques, riches en smectite et des casses de briques broyées. Des quantités de 5, 10, 15 et 20% de briques broyées ont été ajoutées à la pâte destinée à la confection des briques. Des analyses minéralogiques par diffraction des rayons X (DRX), chimiques par spectrométrie de fluorescence (XRF), granulométrique par granulométrie laser, ainsi que les limites d’Atterberg ont été effectuées. Les résultats minéralogiques montrent une diminution de la teneur en carbonates (calcite) et en argile totale (principalement smectite), lors des ajouts successifs de briques broyées. La fraction sableuse augmente progressivement, jusqu’à atteindre 30% pour une formulation avec 20% de casses de briques. Cette granulométrie plus grossière diminue la plasticité de la pâte et permet d’éviter les déformations et les fissures pendant le processus du séchage. De plus, l’ajout des casses de briques dilue les carbonates, ce qui permet d’améliorer la qualité du produit cuit. Ces résultats indiquent que le recyclage des déchets de briques, présente un intérêt à la fois économique et écologique. Des essais de comportement au séchage et à la cuisson ainsi que des essais mécaniques complèteront cette étude. [less ▲]

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See detailUTILISATION DES RESIDUS DE LAVAGE DES GRANULATS DE CARRIERES DANS L’ELABORATION DE PIECES CERAMIQUES (REGION DE TAMAZOUZT, MAROC).
El Boudour El Idrissi, Hicham ULg; Daoudi, Lahcen; El Ouahabi, Meriam ULg et al

Conference (2014, October 27)

Le site potier de Tamazouzt est situé à 40 km au Sud-Est de la ville de Marrakech. La production est sous forme de poterie décorative d’ustensiles rustiques. La matière première utilisée dans ... [more ▼]

Le site potier de Tamazouzt est situé à 40 km au Sud-Est de la ville de Marrakech. La production est sous forme de poterie décorative d’ustensiles rustiques. La matière première utilisée dans l’élaboration de ces produits est issue de résidus de lavage des carrières de granulats exploités le long des oueds. En plus de la qualité des produits et des rendements élevés, ce site donne un bon exemple de valorisation des résidus de lavage qui causent des problèmes pour l’environnement et pour les industriels. Nous avons caractérisé cette matière première afin d’en faire la promotion et d’encourager l’exploitation de tels matériaux dans le domaine de la céramique à l’échelle globale. Les résultats des analyses montrent que la pâte est constituée de 62% d’argiles, 23% de limons et 15% de sables ; l’indice de plasticité est de l’ordre de 16. Pour 27% d’humidité, le degré de retrait au séchage ne dépasse pas 6%. La minéralogie indique la présence de quartz (32%), plagioclase (20%), feldspaths potassiques (10%), calcite (3%) et argile (31%). Les minéraux argileux sont constitués d’illite (16%), de chlorite (7%), de kaolinite (4%) et de vermiculite (4%). La teneur en matière organique est de 4%. La composition chimique est surtout silico-alumineuse (64% de SiO2, 17% d’Al2O3). Les autres éléments majeurs dont la teneur est significative (> 1%) sont : Fe2O3 (8%), MgO (4%), K2O (3%), CaO (3%), Na2O (2%). Les pièces cuites à 1050°C présentent 2% de retrait, 13% de porosité à l’eau, la résistance mécanique à la compression et à la flexion est respectivement de 63 et 20 Mpa. L’analyse DRX des pièces cuites à 1050°C a montré l’apparition de géhlénite, anorthite, diopside et d’hématite. Ces résultats indiquent qu’en plus de l’utilisation locale dans la poterie décorative ces argiles pourraient être valorisées comme matériaux de construction vue leur caractère isolant (bonne porosité), résistance (bon comportement mécanique) et leur couleur rouge (présence de l’hématite). [less ▲]

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See detailL’exemple historique dans la pensée de Machiavel et de Guichardin
Moreno, Paola ULg

Scientific conference (2014, October 23)

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See detailDe l’homme de laboratoire à l’homme en situation : La rigueur d’une phénoménologie clinique
Englebert, Jérôme ULg

Scientific conference (2014, October 17)

Nous voudrions d’abord revenir sur de fausses évidences attachées aux différences entre pratique clinique et recherche. Nous sommes convaincu que la complexité, la rigueur, l’efficacité, voire une ... [more ▼]

Nous voudrions d’abord revenir sur de fausses évidences attachées aux différences entre pratique clinique et recherche. Nous sommes convaincu que la complexité, la rigueur, l’efficacité, voire une hypothétique véracité ne se situent pas, par nature et par principe, uniquement du côté de la recherche fondamentale au détriment d’une pratique clinique qui serait plus intuitive et moins rigoureuse. Nous proposerons ensuite un modèle de recherche directement inscrit dans le paradigme clinique. La psychopathologie phénoménologique, courant émergeant dans la littérature internationale, se caractérise par deux influences majeures : d’une part l’héritage de la réflexion de la philosophie et, d’autre part, elle trouve ses fondements – ses données pourrions-nous dire – dans l’observation de l’homme en situation, c’est-à-dire dans cette pratique clinique. Nous prendrons pour exemples différentes psychopathologies (schizophrénie, anorexie, psychopathie) qui nous permettront de suggérer que la compréhension du patient, et la rencontre de sa subjectivité et de sa sensation, ne peut se limiter à la recherche fondamentale et faire l’économie d’une phénoménologie clinique. Enfin, nous conclurons sur la nécessité d’un regard réciproque à poser entre les connaissances issues des protocoles de recherche en laboratoire et le savoir émergeant de la pratique clinique et de la rencontre de l’homme en situation. [less ▲]

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See detailSimulation and optimization of a CHP biomass plant and district heating network
Sartor, Kevin ULg; Quoilin, Sylvain ULg; Dewallef, Pierre ULg

in Applied Energy (2014), 130

Biomass Combined Heat and Power (CHP) plants connected to district heating (DH) networks are recognized nowadays as a very good opportunity to increase the share of renewable sources into energy systems ... [more ▼]

Biomass Combined Heat and Power (CHP) plants connected to district heating (DH) networks are recognized nowadays as a very good opportunity to increase the share of renewable sources into energy systems. However, as CHP plants are not optimized for electricity production, their operation is profitable only if a sufficient heat demand is available throughout the year. Most of the time, pre-feasibility studies are based on peak power demand and business plans only assume monthly or yearly consumption data. This approach usually turns out to overestimate the number of operating hours or oversize the plant capacity. This contribution presents a methodology intended to be simple and effective that provides accurate estimations of economical, environmental and energetic performances of CHP plants connected to district heating networks. A quasi-steady state simulation model of a CHP plant combined with a simulation model of the district heating network installed on the Campus of the University in Liège (Belgium) is used as an application framework to demonstrate the effectiveness of the selected approach. Based on the developed model and actual consumption data, several scenarios for energy savings are considered and ranked. The potential energy savings and resulting energy costs are estimated enabling more general conclusions to be drawn on the opportunity of using district heating networks in urban districts for Western Europe countries. [less ▲]

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See detailMicrocrystalline cellulose, a direct compression binder in a quality by design environment—A review
Thoorens, Grégory; Krier, Fabrice ULg; Leclercq, Bruno et al

in International Journal of Pharmaceutics (2014), 473(1-2), 64-72

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See detailInvestigation of shear stress evolution during neotissue growth in a perfusion bioreactor using 3d multiphysics modeling
Guyot, Yann ULg; Papantoniou, Ioannis; Schrooten, Jan et al

Conference (2014, October)

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See detailNumerical investigation of cut-edge effect using the Gurson-Tvergaard-Needleman model
Lemoine, Xavier; Tudor, Balan; Habraken, Anne ULg

in Procedia Engineering (2014, October)

In this contribution, the formability of sheet metal cut edges is investigated using damage model.Classical forming limit diagrams are known not to apply properly to the cut edges. However, with mild ... [more ▼]

In this contribution, the formability of sheet metal cut edges is investigated using damage model.Classical forming limit diagrams are known not to apply properly to the cut edges. However, with mild steels the sheet edges usually behave better than the Forming Limit Diagram prédictions, so this phenomenon has not been given sufficient attention. In contrast, for Advanced High Strengh Steels the cut edges exhibit reduced formability as compared to the plain sheet;this effect is very sensitive to the quality of the cutting process. The current investigation is aimed to evaluate the ability of available damage models to predict this effect on sample applications. The Gurson-Tvergaard-Needleman model is used and the material parameters for a Dual Phase are considered [1]. The effect of the cutting process is described by means of initial fields of equivalent plastic strain and porosity. The geometrical distribution and typical values for these two initial fields are devised based on literature . Numerical simulations of flat notched tensile tests are used within the FE code Abaqus/Explicit to illustrate the impact of the initial fields on the moment and the location of the failure initiation. The influence of the mesh size in the cutting-affected area is also investigated. The hole expansion test and a flat bending test are further simulated to investigate the influence of the cut edge. [less ▲]

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See detailVelocity and turbulence measurements for assessing the stability of riverbeds: a comparison between UVP and ADVP
Duma, Diana ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in 11th International Conference on Hydroscience & Engineering - "Hydro-Engineering for Environmental Challenges" (2014, October)

Maintaining the overall stability of active riverbeds requires a deep understanding of the complex interactions between turbulent flow forces and forces stabilizing the riverbed. Standard approaches do ... [more ▼]

Maintaining the overall stability of active riverbeds requires a deep understanding of the complex interactions between turbulent flow forces and forces stabilizing the riverbed. Standard approaches do not properly take into account the turbulence fluctuations in non-uniform flows, while these are of primary importance in the mechanisms determining the stability of stones. In a new approach, the flow forces are quantified by means of parameters combining explicitly the velocity and turbulence distributions over a certain water depth above the riverbed. In this paper, as an onset for using these newly developed bed stability parameters, we report on new experimental measurements of velocity and turbulent kinetic energy based on acoustic methods, whereas all previous uses at the new bed stability parameters relied on Laser PIV Techniques. For quasi-uniform and non-uniform flow conditions, velocity measurements were conducted with two complementary devices: an ultrasonic velocimeter probe (UVP) and an acoustic Doppler velocimeter profiler (ADVP). The results are compared and discussed in detail. A general consistency between the two types of measurements is obtained, while some discrepancies are highlighted close to the bed and tentative explanations are given. [less ▲]

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See detailLes valeurs et les valorisations des images
Dondero, Maria Giulia ULg

in Biglari, Amir (Ed.) Les valeurs. Aux fondements de la sémiotique (2014)

Cet article vise à explorer la manière dont la sémiotique greimassienne a traité la question des valeurs dans le cadre de l’image, notamment photographique et artistique. Après une relecture critique de ... [more ▼]

Cet article vise à explorer la manière dont la sémiotique greimassienne a traité la question des valeurs dans le cadre de l’image, notamment photographique et artistique. Après une relecture critique de l’ouvrage de Jean-Marie Floch, Les formes de l’empreinte, et de la distinction entre valeurs dans l’image et valorisations des images, ce travail se consacre à l’exposition de nouvelles propositions de la sémiotique des pratiques de Jacques Fontanille en essayant de les lier à des réflexions sur les objets et les pratiques de la photographie artistique (l’utilisation des séries, de l’original, des différents tirages, etc.). Si l’attention est portée surtout sur la photo artistique, ce texte envisage également une comparaison avec les pratiques de l’original et de l’authenticité dans la photo de guerre, la photo de famille et la photo-image pieuse. L’objectif majeur de ce travail est d’étudier les diverses pratiques de valorisation des images photographiques afin de faire éclater la notion ontologique de trace photographique. [less ▲]

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See detailAzione, testualizzazione, notazione
Dondero, Maria Giulia ULg

in Espressione e contenuto. Rivista on-line dell'AISS Associazione Italiana di Studi Semiotici (2014, October)

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See detailLes porcheries : réservoirs des culicoïdes (Diptera: Ceratopogonidae), vecteurs des virus de la Maladie de la Langue bleue et de Schmallenberg ?
Zimmer, Jean-Yves ULg; Saegerman, Claude; Martinelle, Ludovic et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014)

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See detailHighly dispersed iron xerogel catalysts for p-nitrophenol degradation by photo-Fenton effects
Mahy, Julien ULg; Tasseroul, Ludivine ULg; Zubiaur, Anthony ULg et al

in Microporous & Mesoporous Materials (2014), 197

Several iron xerogel catalysts were synthesized by hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) which is able to form a chelate with iron ... [more ▼]

Several iron xerogel catalysts were synthesized by hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) which is able to form a chelate with iron ions. The EDAS/TEOS ratio strongly influences the texture of xerogel catalysts. The specific surface area and the micro- and mesoporous volume increase with this ratio. It seems that EDAS plays a nucleating agent role for silica particles and allows to anchor Fe-based moieties inside the silica network. Iron oxide nanoparticles of diameter 1-1.5 nm and Fe3+ ions result, encapsulated in silica particles with sizes of about 10-30 nm in diameter. The iron species was determined by Mössbauer spectroscopy and magnetometry measurements and only Fe3+ species were observed in xerogel catalysts. The Fenton and photo-Fenton effect of these catalysts were evaluated on the degradation of p-nitrophenol in aqueous media under different conditions. Results show that in the presence of H2O2, iron xerogel catalysts present a photo-Fenton effect, reaching 99 % of degradation after 24 h. [less ▲]

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See detailUnderstanding Random Forests: From Theory to Practice
Louppe, Gilles ULg

Doctoral thesis (2014)

Data analysis and machine learning have become an integrative part of the modern scientific methodology, offering automated procedures for the prediction of a phenomenon based on past observations ... [more ▼]

Data analysis and machine learning have become an integrative part of the modern scientific methodology, offering automated procedures for the prediction of a phenomenon based on past observations, unraveling underlying patterns in data and providing insights about the problem. Yet, caution should avoid using machine learning as a black-box tool, but rather consider it as a methodology, with a rational thought process that is entirely dependent on the problem under study. In particular, the use of algorithms should ideally require a reasonable understanding of their mechanisms, properties and limitations, in order to better apprehend and interpret their results. Accordingly, the goal of this thesis is to provide an in-depth analysis of random forests, consistently calling into question each and every part of the algorithm, in order to shed new light on its learning capabilities, inner workings and interpretability. The first part of this work studies the induction of decision trees and the construction of ensembles of randomized trees, motivating their design and purpose whenever possible. Our contributions follow with an original complexity analysis of random forests, showing their good computational performance and scalability, along with an in-depth discussion of their implementation details, as contributed within Scikit-Learn. In the second part of this work, we analyze and discuss the interpretability of random forests in the eyes of variable importance measures. The core of our contributions rests in the theoretical characterization of the Mean Decrease of Impurity variable importance measure, from which we prove and derive some of its properties in the case of multiway totally randomized trees and in asymptotic conditions. In consequence of this work, our analysis demonstrates that variable importances as computed from non-totally randomized trees (e.g., standard Random Forest) suffer from a combination of defects, due to masking effects, misestimations of node impurity or due to the binary structure of decision trees. Finally, the last part of this dissertation addresses limitations of random forests in the context of large datasets. Through extensive experiments, we show that subsampling both samples and features simultaneously provides on par performance while lowering at the same time the memory requirements. Overall this paradigm highlights an intriguing practical fact: there is often no need to build single models over immensely large datasets. Good performance can often be achieved by building models on (very) small random parts of the data and then combining them all in an ensemble, thereby avoiding all practical burdens of making large data fit into memory. [less ▲]

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See detailInter-professional cooperation between family, occupational and social insurance physicians in managing long-term sickness absence
Mairiaux, Philippe ULg; Vanmeerbeek, Marc ULg; Schippers, Nathalie ULg et al

Conference (2014, September 30)

Background In the Belgian health system, sickness absence (SA) management implies complementary roles for general practitioners (GPs), social insurance physicians (SIPs) and occupational physicians (OPs ... [more ▼]

Background In the Belgian health system, sickness absence (SA) management implies complementary roles for general practitioners (GPs), social insurance physicians (SIPs) and occupational physicians (OPs): GPs deliver sick notes and treatment, SIPs control SA benefits and OPs strive to adapt work environments to workers’ remaining capacities. In practice however, there is little cooperation between the three physicians. In 2009, the Ministry of Employment commissioned a study to identify GP-OP-SIP cooperation channels in order to prevent long-term work disability. Methods The study involved two phases. 1) Researchers from the three groups agreed on 15 proposals to enhance cooperation: to establish a formal contact between GP, SIP and OP for patients with > 3 months SA (n=3) ; SIP decision to end SA benefit to be forwarded to the GP (n=2) ; work-related information to be provided by the OP to GP and/or SIP (n=4); website giving contact data of GPs, SIPs, and OPs (n=2) ; initial and continuous education focusing on inter-physician cooperation (n=3); electronic data exchange when dealing with long-term SA (n=1). 2) A Delphi study was conducted in 2012 to validate these proposals: 61 experts representing professional groups of physicians (GP, SIP, OP), patients, government, employers and labor unions were asked to participate. A 18-items questionnaire (the 15 proposals and 3 open questions) was used in a 2-round Delphi study. Proposals were accepted if 80% of experts agreed. For drafting the final proposals, the research team relied on a multidisciplinary expert group. Results Participation rate was 77% (47/61 experts) in round 1 and 7 out of the 15 proposals were accepted. During round 2, participation rate was 94% (44/47); 2 of the remaining proposals reached agreement level. Public authorities were thus advised to invest in a) promotion of pre-return to work visit with the OP for sick-listed patients; b) a website with OPs contact data; c) joint guidelines for return to work guidance; d) joint training of the 3 physician groups; 5) methods ensuring safe electronic information exchange. Conclusions The need for inter-physician cooperation in disability management may exceed individual goodwill and should best be organised by public authorities. The current study may be a first step in this process. [less ▲]

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See detailPrevenção Quaternária e limites em medicina
Jamoulle, Marc ULg; Gomes, Luis

in Revista Brasileira de Medicina de Família e Comunidade (2014), 9(31),

O conceito de Prevenção Quaternária, um questionamento sobre a base da ação médica, nasceu na articulação da relação médico-paciente. Refere-se a toda a atividade médica, sendo uma importante ferramenta ... [more ▼]

O conceito de Prevenção Quaternária, um questionamento sobre a base da ação médica, nasceu na articulação da relação médico-paciente. Refere-se a toda a atividade médica, sendo uma importante ferramenta para a medicina de família. É uma interrogação ética sobre os excessos da demasiada e demasiadamente pouca medicina e fornece algumas respostas. [less ▲]

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See detailTable ronde autour de "Psychopathologie de l'homme en situation"
Englebert, Jérôme ULg

Scientific conference (2014, September 29)

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