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See detailHybrid processing of SCADA and synchronized phasor measurements for tracking network state
Alcaide-Moreno, Boris; Fuerte-Esquivel, Claudio; Glavic, Mevludin ULg et al

in Proc. IEEE PES General Meeting (in press)

This paper proposes a new tracking state estimator aimed at following some of the dynamics of the network state (bus voltage phasors) by a hybrid processing of SCADA and synchronized phasor measurements ... [more ▼]

This paper proposes a new tracking state estimator aimed at following some of the dynamics of the network state (bus voltage phasors) by a hybrid processing of SCADA and synchronized phasor measurements. The latter are assumed to be available in limited number. To avoid time skew effects, only the SCADA measurements received since the last execution of the estimator are processed. To ensure observability, estimated SCADA measurements are used as pseudo-measurements. The procedure includes a prediction, an innovation analysis and a correction step. The latter consists of solving a constrained least-squares optimization. The simulation results refer to a test system undergoing large disturbances, evolving to long-term voltage instability or stabilized by emergency control. The proposed method appears to satisfactorily track the overall network evolution, even during those severe conditions. [less ▲]

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See detailJules Destrée animateur de la vie littéraire
Dozo, Björn-Olav ULg

in Institut Destrée (Ed.) Centenaire de la Lettre au Roi de Jules Destrée (in press)

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See detailChronos et la clé du temps
Désert, Jean-Benoît ULg; Charon, valérie; Triffaux, Jean-Marc ULg

in Revue des Hôpitaux de Jour Psychiatriques et des Thérapies Institutionnelles (in press), 15(15), 79-85

L’argument de ce XLème Colloque des Hôpitaux de jour psychiatriques nous a plongés dans un abîme de questionnements théoriques et pratiques. Défiés par cette immersion dans les tréfonds du modèle, nous ... [more ▼]

L’argument de ce XLème Colloque des Hôpitaux de jour psychiatriques nous a plongés dans un abîme de questionnements théoriques et pratiques. Défiés par cette immersion dans les tréfonds du modèle, nous avons choisi de nous accrocher aux fondements de notre univers. La mythologie grecque sera donc notre source d’inspiration en mettant un dieu antique à notre disposition. Chronos sera notre guide dans un périple réflexif soumettant nos théories et notre pratique à l’épreuve du temps. Le récit de la conception d’un atelier thérapeutique, l’atelier « Art & Temps », sera notre fil d’Ariane dans notre tentative de symboliser notre pratique thérapeutique quotidienne et ses enjeux. Par la suite, l’exposé d’un cas clinique concrétisera un raisonnement théorique visant à situer notre modèle de prise en charge dans le réseau psychiatrique global. [less ▲]

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See detailRisques d'inégalités liés à certaines caractéristiques des manuels contemporains de langues modernes
Simons, Germain ULg; Delbrassine, Daniel ULg; Van Hoof, Florence ULg

in Recherche en Education (2016), 25

Cet article épingle huit caractéristiques de trois manuels de langues contemporains (anglais, allemand, espagnol), qui présentent des risques d'inégalités pour les apprenants. Chacune des caractéristiques ... [more ▼]

Cet article épingle huit caractéristiques de trois manuels de langues contemporains (anglais, allemand, espagnol), qui présentent des risques d'inégalités pour les apprenants. Chacune des caractéristiques est illustrée par des exemples issus des trois manuels. [less ▲]

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See detailConscience et représentation. Introduction aux théories représentationnelles de l'esprit
Dewalque, Arnaud ULg; Gauvry, Charlotte ULg

Book published by Vrin (2016)

L’ambition de ce volume est d’introduire le lecteur aux débats récents, en philosophie de l'esprit, en mettant en lumière les principaux enjeux lié à l’approche représentationnelle de la conscience. Il s ... [more ▼]

L’ambition de ce volume est d’introduire le lecteur aux débats récents, en philosophie de l'esprit, en mettant en lumière les principaux enjeux lié à l’approche représentationnelle de la conscience. Il s'agit de montrer que, derrière l’étiquette de "théories représentationnelles" ou de "représentationalisme" se cachent une variété de positions alternatives : représentationalisme d’ordre supérieur, représentationalisme standard, auto-représentationalisme et théories de l’intentionnalité phénoménale. Il s’agit aussi, simultanément, d’examiner les présupposés théoriques de l’approche représentationnelle, qui est aujourd’hui la plus répandue. Nous avons donc réservé une place, dans ce recueil, à un petit échantillon de perspectives critiques, comme la théorie de l’intentionalisme modal de Tim Crane, le réalisme empirique de Bill Brewer et la critique contextualiste de Charles Travis. [less ▲]

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See detailProvenance of Ichthyosaura alpestris (Caudata: Salamandridae) introductions to France and New Zealand assessed by mitochondrial DNA analysis
Arntzen, Jan W.; King, Tania M.; Denoël, Mathieu ULg et al

in The Herpetological Journal (2016), 26

The last century has seen an unparalleled movement of species around the planet as a direct result of human activity, which has been a major contributor to the biodiversity crisis. Amphibians represent a ... [more ▼]

The last century has seen an unparalleled movement of species around the planet as a direct result of human activity, which has been a major contributor to the biodiversity crisis. Amphibians represent a particularly vulnerable group, exacerbated by the devastating effects of chytrid fungi. We report the malicious translocation and establishment of the alpine newt (Ichthyosaura alpestris) to its virtual antipode in North Island of New Zealand. We use network analysis of mitochondrial DNA haplotypes to identify the original source population as I. a. apuana from Tuscany, Italy. Additionally, a population in southern France, presumed to be introduced, is identified as I. a. alpestris from western Europe. However, the presence of two differentiated haplotypes suggests a mixed origin. This type of analysis is made possible by the recent availability of a phylogenetic analysis of the species throughout its natural range. We discuss the particulars of both introductions. [less ▲]

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See detailLarge predatory marine reptiles from the Albian–Cenomanian of Annopol, Poland
Bardet, Nathalie; Fischer, Valentin ULg; Machalski, Marcin

in Geological Magazine (2016)

During the Early–Late Cretaceous transition, marine ecosystems in Eurasia hosted a diverse set of large predatory reptiles that occupied various niches. However, most of our current knowledge of these ... [more ▼]

During the Early–Late Cretaceous transition, marine ecosystems in Eurasia hosted a diverse set of large predatory reptiles that occupied various niches. However, most of our current knowledge of these animals is restricted to a small number of bonebed-like deposits. Little is known of the geographical and temporal extent of such associations. The middle Albian – middle Cenomanian phosphorite-bearing succession exposed at Annopol, Poland produces numerous ichthyosaurian and plesiosaurian fossils. These are mostly isolated skeletal elements (e.g. teeth, vertebrae), but disarticulated partial skeletons and an articulated, sub vertically embedded ichthyosaur skull are also available. The following taxa are identified: ‘Platypterygius’ sp., cf. Ophthalmosaurinae, Ichthyosauria indet., Polyptychodon interruptus, Pliosauridae indet., Elasmosauridae<indet. and Plesiosauria indet. The large-sized ichthyosaur ‘Platypterygius’ and the pliosaurid Polyptychodon interruptus predominate within the upper Albian – middle Cenomanian deposits. The Annopol record, combined with data from England, France and western Russia, suggests that ‘Platypterygius’ and Polyptychodon interruptus formed a long-term, stable ecological sympatry in marine ecosystems of the European archipelago, at least during the Albian – middle Cenomanian. In addition, the marine reptile assemblage from Annopol is distinct from other Eurasian ecosystems in containing also elasmosaurids in its Albian portion. [less ▲]

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See detailA probabilistic model for predicting the uncertainties of the humid stiction phenomenon on hard materials
Hoang Truong, Vinh ULg; Wu, Ling ULg; Paquay, Stéphane et al

in Journal of Computational & Applied Mathematics (2015), 289

Stiction is a major failure in microelectromechanical system (MEMS) devices in which two contacting surfaces can remain stuck together because of the adhesive forces. Due to the difference between the ... [more ▼]

Stiction is a major failure in microelectromechanical system (MEMS) devices in which two contacting surfaces can remain stuck together because of the adhesive forces. Due to the difference between the surfaces roughness and the adhesive force range, the real contact areas are usually smaller than the apparent one, resulting in a scatter in the adhesive forces. Consequently, the stiction is an uncertain phenomenon. In this work, we develop a probabilistic model to predict the uncertainties of stiction due to the capillary forces acting on stiff materials. This model contains two levels: at the deterministic level, the model can predict the pull-out adhesive contact forces for a given surface topology; at the probabilistic level, the model generates independent identically distributed surfaces on which the deterministic solution can be applied to evaluate the uncertainties related to the stiction phenomenon. [less ▲]

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See detailDevelopment and validation of a short Italian UPPS-P Impulsive Behavior Scale
D'Orta, Isabella; Burnay, Jonathan ULg; Aiello, Daniela et al

in Addictive Behaviors Reports (2015), 2

Impulsivity is a multidimensional construct that plays a prominent role in the development, maintenance, and relapse of addictive disorders. The UPPS-P model of impulsivity, which distinguishes between ... [more ▼]

Impulsivity is a multidimensional construct that plays a prominent role in the development, maintenance, and relapse of addictive disorders. The UPPS-P model of impulsivity, which distinguishes between five impulsivity components (positive urgency, negative urgency, lack of perseverance, lack of premeditation, sensation seeking), has been increasingly investigated during the last decade in relation to addictive and risky behaviors. Unfortunately, it currently lacks a validated scale that allows Italian researchers and clinicians to measure impulsivity based on the UPPS-P model. The current study fills this gap by testing the psychometric properties of a short 20-item Italian scale used to assess the five dimensions of the UPPS-P model in 188 volunteer participants from the community. Confirmatory factor analysis supported a model of five distinct, but interrelated, impulsivity components. The results indicated good internal consistency (Cronbach's α ranges from .73 to .84). Construct validity was evidenced by specific relations with measures of addictive behaviors and depressive symptoms. On the whole, this study demonstrated that the Italian short UPPS-P has good psychometric properties. [less ▲]

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See detailTentative insight into the multiplicity of the persistent dust maker WR 106 from X-ray observations
De Becker, Michaël ULg

in New Astronomy (2015), 41

This paper presents the results of the analysis of the very first dedicated X-ray observation with XMM-Newton of WR 106. This carbon-rich WC9d Wolf–Rayet star belongs to the category of persistent dust ... [more ▼]

This paper presents the results of the analysis of the very first dedicated X-ray observation with XMM-Newton of WR 106. This carbon-rich WC9d Wolf–Rayet star belongs to the category of persistent dust makers (WCd stars). The issue of the multiplicity of these dust makers is pivotal to understand the dust formation process, and in this context X-ray observations may allow to reveal an X-ray emission attributable to colliding-winds in a binary system. The main result of this analysis is the lack of detection of X-rays coming from WR 106. Upper limits on the X-ray flux are estimated, but the derived numbers are not sufficient to provide compelling constraints on the existence or not of a colliding-wind region. Detailed inspection of archive data bases reveals that persistent dust makers have been poorly investigated by the most sensitive X-ray observatories. Certainly, the combination of several approaches to indirectly constrain their multiplicity should be applied to lift a part of the veil on the nature of these persistent dust makers. [less ▲]

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See detailDerivation and Application of Sensitivities to Assess Transient Voltage Sags caused by Rotor Swings
Weckesser, Tilman; Johannsson, Hjortur; Ostergaard, Jacob et al

in International Journal of Electrical Power & Energy Systems (2015), 72

The paper introduces an approach to investigate voltage sags, which are caused by large generator rotor swings following a transient disturbance. Therefore, the method exploits sensitivities derived from ... [more ▼]

The paper introduces an approach to investigate voltage sags, which are caused by large generator rotor swings following a transient disturbance. Therefore, the method exploits sensitivities derived from the algebraic network equations. These provide information on the impact of a generator on the voltage magnitude at a load bus and the e ffect of load variation on the generator's power injection. It is shown that these sensitivities give valuable information to identify critical generator-load pairs and locations for applying preventive control measures. [less ▲]

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See detailA Parallel Processing Approach to Dynamic Simulations of Combined Transmission and Distribution Systems
Aristidou, Petros ULg; Van Cutsem, Thierry ULg

in International Journal of Electrical Power & Energy Systems (2015), 72

Simulating a power system with both transmission and distribution networks modeled in detail is a huge computational challenge. In this paper, a Schur-complement-based domain decomposition algorithm is ... [more ▼]

Simulating a power system with both transmission and distribution networks modeled in detail is a huge computational challenge. In this paper, a Schur-complement-based domain decomposition algorithm is proposed to provide accurate, detailed dynamic simulations of such systems. The simulation procedure is accelerated with the use of parallel programming techniques, taking advantage of the parallelization opportunities inherent to domain decomposition algorithms. The proposed algorithm is general, portable and scalable on inexpensive, shared-memory, multi-core machines. A large-scale test system is used for its performance evaluation. [less ▲]

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See detailNumerical modeling of the cardiac mechano-electric feedback within a thermo-electro-mechanical framework. Study of its consequences on arrhythmogenesis.
Collet, Arnaud ULg

Doctoral thesis (2015)

This doctoral study characterizes, for simple geometries, the cardiac autonomous electrical activity induced by the mechanical deformations of the myocardium via the mechano-electric feedback within a ... [more ▼]

This doctoral study characterizes, for simple geometries, the cardiac autonomous electrical activity induced by the mechanical deformations of the myocardium via the mechano-electric feedback within a thermo-electro-mechanical framework. The underlying fundamental mechanisms are highlighted and discussed in detail. In a healthy heart, the mechano-electric feedback acts as a regulator able to damp mechanical perturbations undergone by the heart, by appropriately modulating electrical activity shortly after these perturbations. In this way, a new healthy electromechanical situation is recovered. However, under certain conditions, this feedback can be a generator of dramatic cardiac arrhythmias by inducing local electrical depolarizations resulting from abnormal cardiac muscle tissue deformations. These local perturbations can then propagate in the whole heart and, thus, lead to global cardiac dysfunctions. The one- and two-dimensional models developed in this work to study the arrhythmogenic consequences of the mechano-electric feedback within a thermo-electro-mechanical framework account for three couplings: the excitation-contraction coupling, the mechano-electric feedback, and the thermo-electric coupling. The excitation-contraction coupling allows the mechanical contraction of cardiac muscle cells resulting from the electrical excitation of these cells, triggered by a propagating action potential initially generated by the sino-atrial node in a healthy heart. The mechano-electric feedback takes into account the influence of mechanical deformations on the electrical activity, both at the cell and the macroscopic level. The thermo-electric coupling then modulates certain electrical properties due to a temperature change. The excitation-contraction coupling is modeled in a phenomenological way by combining the Aliev-Panfilov model and the Rogers-McCulloch model. The propagation of the electrical excitation through cardiac muscle tissue is modeled by using the monodomain approach. The mechano-electric feedback is taken into account by considering two different contributions, namely the physiological contribution (physiological feedback) and the geometric contribution (geometric feedback). The physiological feedback consists in the onset of stretch-activated currents due to the deformations of the cardiac muscle tissue via specific mechanosensitive channels. Regarding the geometric feedback, it simply reflects that the propagation of the depolarization waves is altered by the deformations of the geometry. The thermo-electric coupling is modeled via a dependence with respect to the temperature which is exponential for the gating kinetics of ion channels, exponential for the kinetics of the active tension development in cardiomyocytes, and linear for the ionic conductances. This study shows that the mechano-electric feedback can be arrhythmogenic under specific conditions. In particular, this work clearly reveals that the size of the domain and the importance of stretch-activated currents are key factors in the behavior of the autonomous electrical activity induced by the mechano-electric feedback. This doctoral study also shows that temperature variations such as those undergone by the heart during therapeutic hypothermia or hyperthermia play a central role in the cardiac electromechanical behavior. Moreover, this work emphasizes the influence of the initial conditions on the electromechanical behavior of cardiac tissue. In the one-dimensional framework, an important result of this work is that the disappearance of the autonomous electrical activity induced by the deformations of the cardiac muscle can be associated with different types of bifurcation phenomena, depending on the values of the parameters. These bifurcations, which correspond in fact to different ways for the AEA to vanish, are emphasized and discussed in detail. [less ▲]

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See detailL'enseignement-apprentissage du néerlandais en Fédération Wallonie-Bruxelles: objectifs, méthodes, résultats
Rasier, Laurent ULg; Hiligsmann, Philippe

Conference (2015, September 30)

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See detailAn Ant Colony System for Responsive Dynamic Vehicle Routing
Schyns, Michael ULg

in European Journal of Operational Research (2015), 245(3), 704-718

We present an algorithm based on an Ant Colony System to deal with a broad range of Dynamic Capacitated Vehicle Routing Problems with Time Windows, (partial) Split Delivery and Heterogeneous fleets ... [more ▼]

We present an algorithm based on an Ant Colony System to deal with a broad range of Dynamic Capacitated Vehicle Routing Problems with Time Windows, (partial) Split Delivery and Heterogeneous fleets (DVRPTWSD). Besides the traditional distance criterion, we address the important case of responsiveness. Responsiveness is defined here as completing a delivery as soon as possible, within the time window, such that the client or the truck may restart its activities. This is crucial for many production or service activities in different fields: express parcel deliveries, taxi services, Just in Time production, express repair services, medical care, petrol station replenishment, etc. We develop an interactive web-based solution to allow dispatchers to take new information into account in real-time. The algorithm and its parametrization were tested on real and artificial instances. We first illustrate our approach with a problem submitted by Liege Airport, the 8th biggest cargo airport in Europe. The goal is to develop a decision system to optimize the journey of the refueling trucks. We then consider some classical VRP benchmarks with extensions for more complex problems. [less ▲]

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See detailA stochastic computational multiscale approach; Application to MEMS resonators
Lucas, Vincent ULg; Golinval, Jean-Claude ULg; Paquay, Stéphane et al

in Computer Methods in Applied Mechanics & Engineering (2015), 294

The aim of this work is to develop a stochastic multiscale model for polycrystalline materials, which accounts for the uncertainties in the micro-structure. At the finest scale, we model the micro ... [more ▼]

The aim of this work is to develop a stochastic multiscale model for polycrystalline materials, which accounts for the uncertainties in the micro-structure. At the finest scale, we model the micro-structure using a random Voronoi tessellation, each grain being assigned a random orientation. Then, we apply a computational homogenization procedure on statistical volume elements to obtain a stochastic characterization of the elasticity tensor at the meso-scale. A random field of the meso-scale elasticity tensor can then be generated based on the information obtained from the SVE simulations. Finally, using a stochastic finite element method, these meso-scale uncertainties are propagated to the coarser scale. As an illustration we study the resonance frequencies of MEMS micro-beams made of poly-silicon materials, and we show that the stochastic multiscale approach predicts results in agreement with a Monte Carlo analysis applied directly on the fine finite-element model, i.e. with an explicit discretization of the grains. [less ▲]

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See detailCoupled modeling of Excavation Damaged Zone in Boom clay: Strain localization in rock and distribution of contact pressure on the gallery’s lining
Salehnia, Fatemeh ULg; Collin, Frédéric ULg; Li, Xiang Ling et al

in Computers and Geotechnics (2015), 69

Around galleries excavated at depth in geological media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. In the case of a geological disposal system for ... [more ▼]

Around galleries excavated at depth in geological media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. In the case of a geological disposal system for high-level radioactive waste, the resulting change in the host rock properties in this damaged zone may potentially be important with respect to the long-term evolution and the performance of that system. In this context, predicting the extent of the so-called Excavation Damaged Zone (EDZ) and, possibly, the fractures' network topology remains a challenge. This study is aimed to simulate numerically the extension of this zone at the large scale's excavation, around the Connecting gallery (HADES URL, Mol, Belgium), in Boom clay host rock through analyzing the evolution of strain localization in shear bands mode. To realistically model the involved phenomena, the concrete lining is considered on the gallery wall highlighting its impacts on the evolution of convergence and EDZ around the gallery. The focus of the current paper is made on analyzing the coupled hydro-mechanical behavior of Boom clay host rock during and after the gallery excavation with respect to the evolution of localized shear bands around the gallery. This study is accompanied by the analysis of the contact mechanism on the interface between the clay massive and the lining. The obtained results reveal some interesting features regarding the contact phenomenon relatively to the evolution pattern of shear bands within the clay around the gallery. To assess the reliability of the proposed approach, a discussion on some in-situ observations during the gallery's construction is also performed based on which a good agreement is found between the in-situ evidence and simulated results. [less ▲]

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See detailA perfect estimation of a background image does not lead to a perfect background subtraction: analysis of the upper bound on the performance
Pierard, Sébastien ULg; Van Droogenbroeck, Marc ULg

in International Conference on Image Analysis and Processing (ICIAP) (2015, September)

The quest for the “best” background subtraction technique is ongoing. Despite that a considerable effort has been undertaken to develop flexible and efficient methods, some elementary questions are still ... [more ▼]

The quest for the “best” background subtraction technique is ongoing. Despite that a considerable effort has been undertaken to develop flexible and efficient methods, some elementary questions are still unanswered. One of them is the existence of an intrinsic upper bound to the performance. In fact, data are affected by noise, and therefore it is illusory to believe that it is possible to achieve a perfect segmentation. This paper aims at exploring some intrinsic limitations of the principle of background subtraction. The purpose consists in studying the impact of several limiting factors separately. One of our conclusions is that even if an algorithm would be able to calculate a perfect background image, it is not sufficient to achieve a perfect segmentation with background subtraction, due to other intrinsic limitations. [less ▲]

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See detailSimple median-based method for stationary background generation using background subtraction algorithms
Laugraud, Benjamin ULg; Pierard, Sébastien ULg; Braham, Marc ULg et al

in International Conference on Image Analysis and Processing (ICIAP) (2015, September)

The estimation of the background image from a video sequence is necessary in some applications. Computing the median for each pixel over time is effective, but it fails when the background is visible for ... [more ▼]

The estimation of the background image from a video sequence is necessary in some applications. Computing the median for each pixel over time is effective, but it fails when the background is visible for less than half of the time. In this paper, we propose a new method leveraging the segmentation performed by a background subtraction algorithm, which reduces the set of color candidates, for each pixel, before the median is applied. Our method is simple and fully generic as any background subtraction algorithm can be used. While recent background subtraction algorithms are excellent in detecting moving objects, our experiments show that the frame difference algorithm is a technique that compare advantageously to more advanced ones. Finally, we present the background images obtained on the SBI dataset, which appear to be almost perfect. The source code of our method can be downloaded at http://www.ulg.ac.be/telecom/research/sbg . [less ▲]

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