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See detailApplication des méthodes d'analyse stochastique à l’étude des effets du vent sur les structures du génie civil
Denoël, Vincent ULg

Doctoral thesis (2005)

In the civil engineering field, the analysis of structures subjected to wind loading is generally based on several hypotheses. Their justification is often fuzzy and they are usually postulated in order ... [more ▼]

In the civil engineering field, the analysis of structures subjected to wind loading is generally based on several hypotheses. Their justification is often fuzzy and they are usually postulated in order to apply simplified mathematics. These hypotheses allow the resolution to be run in a gaussian context. This work aims at presenting and applying an analysis which allows accounting for the usually neglected terms of the loading. When studying multi degree of freedom structures, other simplifications concerning the coupling effects between modes are generally formulated. These conditions are also approached and several solutions to take them (eventually partially) into account are proposed. From the simplest analysis of a single degree of freedom system subjected to a simple aerodynamic loading, this work presents more and more complex structures. The last step is to present to developments necessary to analyse a real structure. The developments will allow to analyse a linear 3-D structure subjected to a 3-D aerodynamic field whose non linear characteristics are taken into account. These non linear effects can come from the quadratic terms in the expression of the turbulence and from the non linearity of the aerodynamic coefficients in terms of the wind angle of attack. [less ▲]

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See detailFuzzy k-NN applied to moulds detection
Kuske, Martyna; Rubio, R.; Romain, Anne-Claude ULg et al

in Sensors and actuators. B, Chemical (2005), 106(1), 52-60

The possibility to detect Aspergillus versicolor growing on different building materials by a metal oxide sensor array is studied. Results show that an accurate classification rate of 89 +/- 3% can be ... [more ▼]

The possibility to detect Aspergillus versicolor growing on different building materials by a metal oxide sensor array is studied. Results show that an accurate classification rate of 89 +/- 3% can be obtained combining an extended linear discriminant analysis plus a fuzzy k-NN classifier. The classification ability of the classifier is assessed within the dataset by crossvalidation and also in a second dataset collected 5 months later. There is a slight decrease in the classification performance for all the algorithms, being the most sensitive the most accurate one. [less ▲]

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See detailMicrobial volatile organic compounds as indicators of fungi. Can an electronic nose detect fungi in indoor environments?
Kuske, Martyna; Romain, Anne-Claude ULg; Nicolas, Jacques ULg

in Building and Environment (2005), 40(6), 824-831

The paper presents a review of several studies on the detection of microbial volatile organic compounds (MVOCs) considered as indicators of fungal contamination. As fungi produce specific profiles, or ... [more ▼]

The paper presents a review of several studies on the detection of microbial volatile organic compounds (MVOCs) considered as indicators of fungal contamination. As fungi produce specific profiles, or fingerprints of volatile compounds, the electronic nose technology is a very promising opportunity for rapid and non costly detection of fungi in buildings. E-noses are able to distinguish between mouldy and non-mouldy samples, and also to recognise certain species of fungi. However, two limiting factors may appear decisive for employment of electronic noses in indoor fungi detection: low concentrations of MVOCs and presence of interfering substances in indoor environments. [less ▲]

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See detailApprentissage lexical et généralisation chez les enfants retardés mentaux
Elbouz, Mouna; Comblain, Annick ULg

in Groosmann, F.; Paveau, M. A.; Petit, G. (Eds.) Didactique du lexique : langue, cognition, discours (2005)

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See detailOn multi-area control in electric power systems
Zima, Marek; Ernst, Damien ULg

in Proceedings of the 15th Power System Computation Conference (PSCC 2005) (2005)

In this paper we study the concept of electric power system control, when the responsibility for controlling the entire system is shared by agents controlling their assigned areas. Within this framework ... [more ▼]

In this paper we study the concept of electric power system control, when the responsibility for controlling the entire system is shared by agents controlling their assigned areas. Within this framework, we suggest to study the dynamics created by the interactions of agents. In particular, we discuss the relation that exists between the information available to the different agents and their optimisation objective, and the performance of the overall power system. Simulations results, carried out on a 39-node power system voltage control problem, are provided and analyzed. They highlight, among others, the sub-optimal performance level attained by the system when the different agents exchange information about their area dynamics without sharing a common control objective. [less ▲]

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See detailApplication of an advanced transient stability assessment and control method to a realistic power system
Cirio, D.; Lucarella, D.; Vimercati, G. et al

in Proceedings of the 15th Power System Computation Conference (PSCC 2005) (2005)

The paper presents a technical overview of a large research project on Dynamic Security Assessment (DSA) supported by EU. Transient Stability Assessment and Control, which was one of the main goals of the ... [more ▼]

The paper presents a technical overview of a large research project on Dynamic Security Assessment (DSA) supported by EU. Transient Stability Assessment and Control, which was one of the main goals of the project, is taken into consideration by presenting the fundamental theoretical methodology and possible applications. A specific prototype installation for a realistic power system is then reported by presenting and commenting some of the obtained results. [less ▲]

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See detailA comparison of Nash equilibria analysis and agent-based modelling for power markets
Krause, Thilo; Andersson, Goran; Ernst, Damien ULg et al

in Proceedings of the 15th Power System Computation Conference (PSCC 2005) (2005)

In this paper we compare Nash equilibria analysis and agent-based modelling for assessing the market dynamics of network-constrained pool markets. Power suppliers submit their bids to the market place in ... [more ▼]

In this paper we compare Nash equilibria analysis and agent-based modelling for assessing the market dynamics of network-constrained pool markets. Power suppliers submit their bids to the market place in order to maximize their payoffs, where we apply reinforcement learning as a behavioral agent model. The market clearing mechanism is based on the locational marginal pricing scheme. Simulations are carried out on a benchmark power system.We show how the evolution of the agent-based approach relates to the existence of a unique Nash equilibrium or multiple equilibria in the system. Additionally, the parameter sensitivity of the results is discussed. [less ▲]

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See detailNew developments in the application of automatic learning to power system control
Wehenkel, Louis ULg; Glavic, Mevludin; Ernst, Damien ULg

in Proceedings of the 15th Power System Computation Conference (PSCC 2005) (2005)

In this paper we present the basic principles of supervised learning and reinforcement learning as two complementary frameworks to design control laws or decision policies within the context of power ... [more ▼]

In this paper we present the basic principles of supervised learning and reinforcement learning as two complementary frameworks to design control laws or decision policies within the context of power system control. We also review recent developments in the realm of automatic learning methods and discuss their applicability to power system decision and control problems. Simulation results illustrating the potentials of the recently introduced fitted Q iteration learning algorithm in controlling a TCSC device aimed to damp electro-mechanical oscillations in a synthetic 4-machine system, are included in the paper. [less ▲]

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See detailApproximate value iteration in the reinforcement learning context. Application to electrical power system control
Ernst, Damien ULg; Glavic, Mevludin; Geurts, Pierre ULg et al

in International Journal of Emerging Electrical Power Systems (2005), 3(1),

In this paper we explain how to design intelligent agents able to process the information acquired from interaction with a system to learn a good control policy and show how the methodology can be applied ... [more ▼]

In this paper we explain how to design intelligent agents able to process the information acquired from interaction with a system to learn a good control policy and show how the methodology can be applied to control some devices aimed to damp electrical power oscillations. The control problem is formalized as a discrete-time optimal control problem and the information acquired from interaction with the system is a set of samples, where each sample is composed of four elements: a state, the action taken while being in this state, the instantaneous reward observed and the successor state of the system. To process this information we consider reinforcement learning algorithms that determine an approximation of the so-called Q-function by mimicking the behavior of the value iteration algorithm. Simulations are first carried on a benchmark power system modeled with two state variables. Then we present a more complex case study on a four-machine power system where the reinforcement learning algorithm controls a Thyristor Controlled Series Capacitor (TCSC) aimed to damp power system oscillations. [less ▲]

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See detailPreventive and emergency control of power systems
Wehenkel, Louis ULg; Ruiz-Vega, Daniel; Ernst, Damien ULg et al

in Real Time Stability in Power Systems - Techniques for Early Detection of the Risk of Blackout (2005)

A general approach to real-time transient stability control is described, yielding various complementary techniques: pure preventive, open loop emergency, and closed loop emergency controls. The ... [more ▼]

A general approach to real-time transient stability control is described, yielding various complementary techniques: pure preventive, open loop emergency, and closed loop emergency controls. The organization of the resulting control schemes is then revisited in order to make it able to cover static and voltage security, in addition to transient stability. Distinct approaches for preventive and emergency operating conditions are advocated. [less ▲]

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See detailCorpus mechanicum versus corpus mysticum : des conflits entre l'auteur d'une oeuvre et le propriétaire du support
Vanbrabant, Bernard ULg

in Revue de la Faculté de Droit de l'Université de Liège (2005), (4), 490-562

About the conflicts arising between the author and owner of a work of art: multiplicity thereof and how to resolve them

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See detailA propos de l'image des biens
Vanbrabant, Bernard ULg

in Droit des biens (2005)

About the right of the owner of a physical property, typically an immoveable, to oppose third parties taking/exploiting pictures thereof

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See detailLa vente aux consommateurs après la loi du 1er septembre 2004
Vanbrabant, Bernard ULg

in Revue de la Faculté de Droit de l'Université de Liège (2005)

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See detailLa compétence territoriale en matière de saisie-description, aujourd'hui et demain
Vanbrabant, Bernard ULg; Van Couter, Yves

in Revue de Jurisprudence de Liège, Mons et Bruxelles (2005), (9), 395

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See detailTemporal evolution of sediment supply in Lago Puyehue (Southern Chile) during the last 600 yr and its climatic significance
Bertrand, S.; Boes, X.; Castiaux, J. et al

in Quaternary Research (2005), 64(2), 163-175

Short-term climate changes in Southern Chile are investigated by a multi-proxy analysis of a 53-cm-long sedimentary sequence selected among eight short cores retrieved in Lago Puyehue (Chile, 40 degrees S ... [more ▼]

Short-term climate changes in Southern Chile are investigated by a multi-proxy analysis of a 53-cm-long sedimentary sequence selected among eight short cores retrieved in Lago Puyehue (Chile, 40 degrees S). This core contains a 600-yr-long undisturbed record of paleo-precipitation changes. Two measurement methods for sediment density, organic matter and biogenic silica contents are compared and the most appropriate techniques are selected. Together with aluminium and titanium concentrations, grain size and geochemical properties of the organic matter, these proxies are used to demonstrate paleo-precipitation changes around 40 degrees S. Increase of terrigenous particle supply between A.D. 1490 and A.D. 1700 suggests a humid period. Contemporaneously, delta C-13 data show increasing lake productivity, in response to the high nutrient supply. The A.D. 1700-1900 interval is characterized by a decreasing terrigenous supply and increasing delta C-13 values, interpreted as a drying period. The magnetic susceptibility signal, reflecting the terrigenous/biogenic ratio, demonstrates that similar variations occur in all the undisturbed sedimentary environments of Lago Puyehue. The A.D. 1490-1700 wet period is associated with the onset of the European Little Ice Age (LIA) and interpreted as its local signature. This work supports the fact that the LIA was a global event, not only restricted to the Northern Hemisphere. (c) 2005 University of Washington. All rights reserved. [less ▲]

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See detailThree metacognitive indices of realism in self assessment
Leclercq, Dieudonné ULg; Poumay, Marianne ULg

Learning material (2005)

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See detailSedimentary dynamics on isolated highs in Lake Baikal: evidence from detailed high-resolution geophysical data and sediment cores
Charlet, F.; Fagel, Nathalie ULg; De Batist, M. et al

in Global and Planetary Change (2005), 46(1-4), 125-144

High- and very-high-resolution seismic data, side-scan sonar mosaics and piston cores from three isolated highs in Lake Baikal (Vydrino Shoulder, Posolsky Bank, Continent Ridge) have allowed to document ... [more ▼]

High- and very-high-resolution seismic data, side-scan sonar mosaics and piston cores from three isolated highs in Lake Baikal (Vydrino Shoulder, Posolsky Bank, Continent Ridge) have allowed to document in unprecedented detail the depositional, re-depositional and tectonic processes and to characterise the overall sedimentary environment on such isolated highs. Our data show that Vydrino Shoulder actually represents a turbidity- or underflow-sourced slope fan, with a distinct channel-levee morphology, and affected by tectonics and stratigraphic unconformities. Sediment cores contain up to 90% of terrigenous material. Posolsky Bank is a major tilted fault block, clearly affected by tectonic activity, by stratigraphic unconformities and by mass wasting along its margins. Sedimentation on its crest is undisturbed, but average sedimentation rates are high due to the influence of the nearby Selenga River. Continent Ridge is also affected by active faulting, stratigraphic unconformities and by mass-wasting along its flanks. The area receives only 30% of terrigenous input. There are no signs of sediment reworking due to bottom-currents. Our study thus shows that in comparison with other environments in Lake Baikal, the isolated highs probably hold the best potential to contain a high-quality, continuous, undisturbed and undiluted sedimentary record suitable for paleoclimate research. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailEstimation de la pollution particulaire naturelle de l’air en 2003 à Niamey (Niger) à partir de données de visibilité horizontale
Ozer, Pierre ULg

in Environnement Risques & Santé (2005), 4(1), 43-49

There is no longer any question that air pollution in the form of large quantities of total suspended particulates (TSP) and particulate matter less than 10 µm in aerodynamic diameter (PM 10) harms human ... [more ▼]

There is no longer any question that air pollution in the form of large quantities of total suspended particulates (TSP) and particulate matter less than 10 µm in aerodynamic diameter (PM 10) harms human health. Deterioration in air quality due to high concentrations of mineral dust from Africa affects the US and Europe, although most of these countries are far from the Sahara. Surprisingly, no estimates of TSP or PM 10 levels near the Saharan dust source are available. Measurements taken at Niamey-Airport in Niger of horizontal visibility, which is reduced by the presence of dust in the atmosphere, allowed us to estimate TSP and PM 10 levels according various relations found in the literature. Both the magnitude and frequency of mineral particle concentrations are very high. The average yearly concentration is estimated at 103 µg.m -3 TSP and 67 µg.m -3 PM 10. These very high particulate levels present a real public health threat to which national and international policy-makers must respond. [less ▲]

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See detailTsunami en Asie du Sud-Est : analyse de son importance dans la presse écrite, des coûts assurés et du nombre de victimes à Sumatra
De Longueville, Florence ULg; Ozer, Pierre ULg

in Bulletin de la Société Géographique de Liège (2005), 46

The tsunami that affected the Indian ocean’s rims on December 26, 2004 claimed close to 300 000 deaths, essentially on the island of Sumatra, Indonesia, which suffered overwhelming devastation. This ... [more ▼]

The tsunami that affected the Indian ocean’s rims on December 26, 2004 claimed close to 300 000 deaths, essentially on the island of Sumatra, Indonesia, which suffered overwhelming devastation. This article is focused on three specific aspects of the disaster. On one side, we analyse the tribune offered to the tsunami catastrophe by the press in Le Soir and Le Monde. On the other side, we present an analysis of the distribution of insured losses from the latest data made available by the two largest reinsurance world companies, Swiss Re and Munich Re. Finally, we try to compare the estimated death toll with available demographic data for the province of Aceh. Here we show that the place given to the tsunami is enormous when compared to other natural tragedies, and we try to explain what motivated such a coverage. In addition, the analysis of insured losses highlights the North-South differences as local victims (99 %) concentrate less than 10 % of the losses supported by insurers. For what regards the death toll, we conclude that the number of about 235 000 for northern Indonesia is a broad estimation and that a realistic approach is impossible since no census was made in this region over the last three decades. [less ▲]

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