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See detailLa gestion participative : vernis à la mode ou vrai outil de l'ingénieur ?
Vermeulen, Cédric ULg

Conference given outside the academic context (2015)

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See detailDe l’intérêt des circuits-courts alimentaires en réponse au défi climatique. Exemples concrets en région liégeoise
Ozer, Pierre ULg; Caprioli, Philippe

Conference given outside the academic context (2015)

Detailed reference viewed: 28 (2 ULg)
See detailVoyages dans l’image. Le cinéma, machine du mouvement virtuel entre relief et profondeur
Tomasovic, Dick ULg

Scientific conference (2015, May 26)

Depuis les premiers travelogues du catalogue Lumière jusqu’aux derniers avatars des projections en 3D numérique, le cinéma s’est employé à faire voyager le spectateur, à lui donner l’impression d’être en ... [more ▼]

Depuis les premiers travelogues du catalogue Lumière jusqu’aux derniers avatars des projections en 3D numérique, le cinéma s’est employé à faire voyager le spectateur, à lui donner l’impression d’être en mouvement, de lui faire fantasmer la possibilité d’entrer dans l’image. À travers le commentaire d’une série d’œuvres filmiques, issues principalement de la grande production divertissante du cinéma (et particulièrement de l’industrie du blockbuster, modèle d’un certain cinéma d’attraction), cette intervention tente de saisir les enjeux et les figures du transport du spectateur par les inventions de la mise en scène. [less ▲]

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See detailProcess-based method for groundwater resource vulnerability mapping with regards to solute contamination at the surface
Popescu, Cristina; Brouyère, Serge ULg; Orban, Philippe ULg et al

Conference (2015, May 26)

Numerous groundwater vulnerability methods have been developed taking into consideration a variable number of factors. The most common techniques are based on calculation of an index expressing the ... [more ▼]

Numerous groundwater vulnerability methods have been developed taking into consideration a variable number of factors. The most common techniques are based on calculation of an index expressing the protective effect of underground formations overlying the groundwater resource. However, it has been shown that different overlay and index methods applied to the same system can yield dramatically dissimilar results (among others, Gogu et al., 2003). The limitation of most of these methods is related to their use of a qualitative definition of groundwater vulnerability, as opposed to a definition based on a quantitative description of contaminant migration. A process-based point of view is proposed and based on three factors describing a pollution event (Brouyère et al., 2001): (1) the transit time from the source to the target, (2) the duration of the contamination breakthrough at the target, (3) the ratio between the maximum concentration at the target to the released concentration at the contamination source. The assessment can then be based on the impulse response at the ‘target’ to a Dirac-type solicitation (point, unit mass, instantaneous source of pollution), considering only physical hydrodispersive processes for intrinsic vulnerability and both physical and biochemical processes for specific vulnerability. The breakthrough curve obtained after a vertical transfer through the overlying layers can be computed pixel by pixel. Automatically processing the columns with identical characteristics, 1D partially saturated flow and solute transport computations are performed. Different maps are obtained for the three above mentioned factors. On the basis of these results, different vulnerability maps can be built according to the weighting coefficients agreed by the local community or decision makers. This concept allows a clear distinction between conventional aspects and process-based results in the building of a final vulnerability indicator. This methodology has the further advantage to consider the possible impact of runoff conditions occurring at the land surface and possibly leading to lateral contamination of groundwater through downstream preferential infiltration features. To solve this problem, Popescu et al. (2004 & 2008) and Dassargues et al. (2009) proposed a method for quantifying a lateral “dangerosity” coefficient using runoff coefficients based on land use, slopes, and soil properties. A test application is illustrated on a case-study located in a limestone basin in Belgium. [less ▲]

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See detailPropagation of uncertainties in the modelling of MEMS resonators (using a 3-scale probabilistic approach)
Lucas, Vincent ULg; Wu, Ling ULg; Golinval, Jean-Claude ULg et al

Conference (2015, May 26)

In order to ensure the accuracy of MEMS vibrometers, the first resonance frequency should be predicted at the design phase. However, this prediction is subjected to randomness: there is a scatter in the ... [more ▼]

In order to ensure the accuracy of MEMS vibrometers, the first resonance frequency should be predicted at the design phase. However, this prediction is subjected to randomness: there is a scatter in the reached value resulting from the uncertainties involved in the manufacturing process. The purpose of this work is to take into account these uncertainties of the microstructure. The objective is a non-deterministic model that can be used since the design stage. The material is the source of uncertainties: the beam resonator is made of a polycrystalline material in which each grain has a random orientation. Solving the problem with a full direct numerical simulation combined to a Monte-Carlo method allows the probability density function of the resonance frequency to be computed. However this methodology is computationally expensive due to the number of degrees of freedom required to study one sample, motivating the development of a computationally efficient method. Towards this end a 3-scales stochastic model for predicting the resonance frequency of a micro-beam made of a polycrystalline linear anisotropic material is described. At the lower scale, we model the micro-structure with micro-volume elements. Due to the small-scale involved, the representativity of these micro-volume elements is not achieved and thus Statistical Volume Elements (SVE) are considered. These SVEs are generated under the form of a Voronoï tessellation, each grain being assigned a random orientation. Computational homogenization is applied over the SVEs, along with a Monte-Carlo procedure, to obtain a stochastic characterization of the elasticity tensor at the second scale of interest, the meso-scale. The spatial correlation between SVEs is also estimated. A generator based on spectral methods is implemented. Afterwards, using a stochastic finite element method, these meso-scale uncertainties are propagated by taking account of the spatial correlation up to the higher scale to predict the probabilistic behavior of the MEMS resonator. [less ▲]

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See detailSensitivity and vulnerability to groundwater overexploitation by a ‘pressure state impact’ and process based approach
Beaujean, Jean; Lemieux, Jean-Michel; Therrien, René et al

Conference (2015, May 26)

A methodology is developed for proposing a groundwater vulnerability assessment in a Pressure-State-Impact causal chain that is familiar to decision makers. The ‘Driver Pressure State Impact Response’ ... [more ▼]

A methodology is developed for proposing a groundwater vulnerability assessment in a Pressure-State-Impact causal chain that is familiar to decision makers. The ‘Driver Pressure State Impact Response’ (DPSIR) framework, for describing interactions between society and the environment, defines a chain of Drivers that exert Pressures on the State of a given resource, such as groundwater, which then generates an Impact that will require an appropriate Response (Kristensen, 2004). The method is here based on the calculation of sensitivity coefficients for a user-defined groundwater state for which several physically-based indicators are proposed. These sensitivity coefficients reflect the easiness with which the groundwater state transmits pressures into impacts. They are grouped into a vulnerability matrix of pressures and impacts that quantify vulnerability for every combination of causal links identified in the DPSIR chain. For that reason, the sensitivity coefficients are converted to vulnerability, using the concept of ‘transgressing a given threshold’, which is commonly used in socioeconomic sciences (Luers et al. 2003). The concept of ‘rising above a given concentration threshold’ can be used for groundwater quality issues. The concept of ‘falling below a given piezometric head threshold’ can be used for groundwater quantity issues as aquifer overexploitation problems. Outside the careful selection of the sensitivity analysis method that can significantly influence the computational effort (Beaujean et al., 2013), emphasis is given to the illustration of the general methodology on a simple groundwater quantity case (of an alluvial aquifer with concerns related to water supply) demonstrating the potential use of this general and physically based vulnerability assessment method. While the methodology is general, the choice of causal chains has to be made prior to the calculation. The vulnerability is also related to a damaged state and is related to the ‘distance’ between the current state and a given threshold. This choice is arbitrary such that the vulnerability is sensitive to the choice of the threshold. [less ▲]

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See detailAbout the Regularity of Cantor's Bijection
Simons, Laurent ULg; Nicolay, Samuel ULg

Conference (2015, May 25)

In 1878, Cantor proved that there exists a one-to-one correspondence between the points of the unit line segment [0,1] and the points of the unit square [0,1]². Since this application is defined via ... [more ▼]

In 1878, Cantor proved that there exists a one-to-one correspondence between the points of the unit line segment [0,1] and the points of the unit square [0,1]². Since this application is defined via continued fractions, it is very hard to have any intuition about its smoothness. In this talk, we explore the regularity and the fractal nature of Cantor's bijection, using some notions concerning the metric theory and the ergodic theory of continued fractions. This talk is based on a joint work with S. Nicolay. [less ▲]

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See detailGestion des déchets nucléaires en France et en Belgique: Quelle place pour la critique ?
Parotte, Céline ULg

Conference (2015, May 25)

Depuis les années 1970, avec la multiplication des controverses scientifiques (Callon, Lascoumes et Barthe 2001), souvent liées à des mouvements pacifistes en environnementalistes ; nous assistons à la ... [more ▼]

Depuis les années 1970, avec la multiplication des controverses scientifiques (Callon, Lascoumes et Barthe 2001), souvent liées à des mouvements pacifistes en environnementalistes ; nous assistons à la naissance d’un flux d’incertitude et de critique politico-sociale, dirigée principalement vers le monde scientifique, sa production et ses hésitations. Il est malaisé de prévoir si cela mènera à une réelle désolidarisation des notions de science, technologie et progrès, mais il reste à supposer que cette critique permettra une gestion plus réflexive des effets majeurs du développement scientifique et technologique (Schot et Rip 2009). En d’autres termes, bien que les liens entre les idéologies du progrès et de la technologie restent très souvent puissants et non remis en question, on assiste au même moment à une critique sociale des conséquences sur le processus de gestion des choix technologiques qui s’y rapportent. Cette contribution propose de s’attarder sur le cas de la gouvernance socio technique de la gestion des déchets hautement radioactifs depuis le « tournant participatif » opéré dans les années 90 en France et en Belgique. Il s’agit de poser un regard critique sur l’apparition d’un nouveau mode de gouvernance plus participatif (au travers de l’inclusion de nouveaux acteurs) et ses conséquences. Dans quelle mesure ceux-ci redéfinissent-ils les positionnements du monde scientifique au sein du processus décisionnel ? Comment le monde scientifique reçoit-il les critiques qui lui sont adressées ? Plutôt que des tendances globales, cette contestation témoigne le plus souvent d’une mosaïque d’activités critiques dynamiques, concurrentes ou complémentaires dont les effets semblent faire vaciller — ou à tout le moins mettre sous tension — l’organisation, les routines et les institutions des sociétés modernes (Delvenne 2011). Cette mosaïque reflète le dynamisme des acteurs sociaux qui propagent leurs agendas et défendent leurs intérêts à travers la négociation de concessions, l’enchevêtrement de décisions et la cristallisation de rapports de force. En d’autres termes, les avancées d’un projet comme la gestion des déchets nucléaires ne sont pas la progression inéluctable d’un processus uniformément accepté par toutes les tendances de la société. En réalité, il existe une multitude d’acteurs qui influencent sans cesse la nature de ses contours. Ces acteurs sociaux bénéficient d’espaces politiques et institutionnels divers pour exprimer leurs préférences et tenter de transformer durablement les critiques qu’ils formulent en actions politiques qui trouvent un écho plus large au sein de la société. [less ▲]

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See detailLa culture industrielle de microalgues
Franck, Fabrice ULg

Conference given outside the academic context (2015)

Detailed reference viewed: 18 (1 ULg)
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See detailCharles Juliet : Du portrait a-posteriori à l’écriture de soi L’adresse à la mère comme tentative de désenfouissement dans Lambeaux
Vandormael, Thomas ULg

Conference (2015, May 25)

Lambeaux propose un diptyque de portraits. Dans la première partie, celui de la mère biologique. Dans la seconde, celui de l’auteur lui-même et au sein de celui-ci, enfin, le portrait de la mère adoptive ... [more ▼]

Lambeaux propose un diptyque de portraits. Dans la première partie, celui de la mère biologique. Dans la seconde, celui de l’auteur lui-même et au sein de celui-ci, enfin, le portrait de la mère adoptive. La dimension vocative explicite de la narration en constitue à la fois l’originalité et le paradoxe. Le recours au « Tu » dans l’ensemble du texte fait advenir une poétique de l’adresse en laquelle se cristallise la spécificité du récit de filiation propre à l’autofiction de la littérature contemporaine : différent du simple devoir de mémoire ou encore de la - très en vogue - commémoration, il se situe plutôt du côté de la restitution, à laquelle il y a deux sens à donner : à la fois reconstituer ce qui fut et s’est défait, et rendre leur existence à ceux qui s’en sont trouvés dépouillés en faisant apparaître ce qui demeure enfoui et dont on n’a pu hériter. Pour répondre au silence d’une mère qu’il n’a pas connue et qui elle-même n’a pas pu s’exprimer, faute d’accès au langage ou d’une présence pour l’écouter, Juliet choisit l’instantané et l’immédiateté d’un discours d’interpellation au présent et la forme du dialogue avec les morts, forcément toujours en partie déjà voué à l’échec. Dès lors, notre propos souhaite interroger comment le choix du vocatif permet un dédoublement fécond du sujet,faisant advenir une relation de soi à soi qui déjoue les processus classiques de l'autobiographie. [less ▲]

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See detailElectric current crowding in nanostructured conductors
Silhanek, Alejandro ULg

Conference (2015, May 24)

When current stream lines are forced to depart from their rectilinear trajectory due to the presence of an obstacle, they conglomerate at the sharp bends encountered on their paths. The consequent current ... [more ▼]

When current stream lines are forced to depart from their rectilinear trajectory due to the presence of an obstacle, they conglomerate at the sharp bends encountered on their paths. The consequent current crowding is present in normal metals as well as in superconductors and has been, since long ago, identified as a key player in electromigration phenomena leading to failure in integrated circuit interconnects while might also be at the origin of local ablation in planar plasmonic structures. More recently, current crowding has been recognized as an important factor limiting the performance of superconducting single-photon detectors, leading to flux quanta motion rectification, or being a source of unwanted ratchet signal and depletion of surface barriers for magnetic flux penetration. In this talk, we will also show that in nanostructured superconductors at low temperatures, current crowding can trigger abrupt flux avalanches developing well defined geometrical patterns. Our experimental findings are backed up to the finest details, by simulations based on a phenomenological thermomagnetic model which, in turn, can be used to predict such complex structures and, given its reliability, allows one to estimate physical variables of more difficult experimental access, such as the local values of temperature and electric field. [less ▲]

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See detailLa mondialisation et l’avenir de l’enseignement du français
Defays, Jean-Marc ULg

Scientific conference (2015, May 23)

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See detailDo large scale restoration projects reduce within-species traits variability?
Harzé, Mélanie ULg; Monty, Arnaud ULg; Mahy, Grégory ULg

Conference (2015, May 23)

Dry calcareous grasslands represent local biodiversity hotspots of European temperate regions. They have suffered intensive fragmentations due to due to the abandonment of traditional agropastoral systems ... [more ▼]

Dry calcareous grasslands represent local biodiversity hotspots of European temperate regions. They have suffered intensive fragmentations due to due to the abandonment of traditional agropastoral systems and the resulting encroachment, reforestation, urbanization or transformation into arable lands. In order to preserve and enhance their ecological value, a series of ecological restoration projects have been implemented throughout Europe (LIFE+). As habitats restoration costs can be prohibitive, actions should demonstrate their success. In the face of environmental changes, restored populations should possess attributes necessary for adaptive evolutionary changes allowing them to persist over the long term. Intra-population functional variability expresses the range of possible trait values of a species living in a heterogeneous environment. It results notably from genetic diversity and phenotypic plasticity and enables species survival, growth and reproduction under various environmental conditions. In Belgium, three European LIFE projects have taken place between 2000 and 2009, restoring more than 400 hectares of calcareous grasslands. Restorations have mainly been evaluated in terms of plant species diversity and community composition. Though it is expected to be of crucial importance for species evolutionary potential, the restoration of the entire range of environmental heterogeneity and the resulting intra-population functional variability of restored population have so far not been assessed. We compared the intra-population variability of functional traits (specific leaf area (SLA) and maximum vegetative height) of 10 restored and 10 reference populations of Potentilla neumanniana (30 individuals per populations). We characterized abiotic and biotic conditions by measuring soil depth, sun exposure, bare ground cover and mean vegetation height around each sampled individual. Our main results showed that the range of within-species functional variability was restored in our study area. We will conclude with implications for the evolutionary potential of restored populations and for future ecological restoration projects. [less ▲]

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See detailExploration de facteurs cognitifs et thymiques en lien avec les symptômes psychotiques : Analyses en clusters.
Laloyaux, Julien ULg; Laroi, Frank ULg; Nuyens, Filip et al

Conference (2015, May 22)

Introduction Il est maintenant reconnu qu’il existe différentes trajectoires possibles au développement et au maintien des symptômes psychotiques tels que les hallucinations et les idées délirantes. Ces ... [more ▼]

Introduction Il est maintenant reconnu qu’il existe différentes trajectoires possibles au développement et au maintien des symptômes psychotiques tels que les hallucinations et les idées délirantes. Ces phénomènes sont également en lien avec différents mécanismes cognitifs (e.g. style d’encodage, impulsivité) et facteurs thymiques (e.g. anxiété, dépression). Cependant, le poids de ces facteurs peut certainement varier en fonction des différentes trajectoires. Objectifs L’objectif de cette étude est d’explorer l’impact de différents facteurs cognitifs et thymiques sur les symptômes psychotiques dans un large échantillon issu de la population normale afin d’essayer d’en faire ressortir des profils différents avec l’aide d’analyses en clusters. Les mesures suivantes ont été incluses : Launay-Slade Hallucinations Scale, Schizotypal Personality Questionnaire-Brief, Peters et al. Delusions Inventory, UPPS Impulsive Behavior Scale, Beck Depression Inventory, State-Trait Anxiety Inventory (trait). [less ▲]

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See detailBifurcation Analysis of Large-Scale Dynamical Systems Using the Harmonic Balance Method
Detroux, Thibaut ULg; Renson, Ludovic ULg; Masset, Luc ULg et al

Conference (2015, May 22)

The harmonic balance (HB) method has been widely used in the past few years, as a numerical tool for the study of nonlinear industrial models. However, in its classical formulation the HB method is ... [more ▼]

The harmonic balance (HB) method has been widely used in the past few years, as a numerical tool for the study of nonlinear industrial models. However, in its classical formulation the HB method is limited to the approximation of periodic solutions. The present paper proposes to extend the method to the detection and tracking of codimension-1 bifurcations in the system parameters space. As an application, the frequency response of a spacecraft and its bifurcations are studied, together with two nonlinear phenomena, namely quasiperiodic oscillations and detached resonance curves. [less ▲]

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See detailMake the ureter your friend
Bonnet, Pierre ULg

Conference (2015, May 22)

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See detailEffect of inulin and wheat bran in the creep feed of neonatal piglets
Li, Bing ULg; Leblois, Julie ULg; Bindelle, Jérôme ULg et al

Conference (2015, May 22)

Detailed reference viewed: 13 (5 ULg)