Publications ORBi OA
Bookmark and Share    
Full Text
See detailSolute contaminant transport in variably saturated dual-porosity/ dual permeability chalk: field tracer experiments and modelling
Brouyère, Serge ULg

in Aagaard, Per; Bedbur, Eckart; Bidoglio, Giovanni (Eds.) et al Saturated & unsaturated zone: integration of process knowledge into effective models - COST Action 629 Workshop (2004)

Detailed reference viewed: 11 (4 ULg)
Full Text
See detailStructural damage detection based on PCA of vibration measurements
Golinval, Jean-Claude ULg; De Boe, Pascal; Yan, A. M. et al

in 58th Meeting of the Soc. for Mach. Failure Prevention Tech, Virginia Beach, 2004 (2004)

This paper deals with the application of statistical process control techniques based on principal component analysis to vibration-based damage diagnosis of structures. Principal component analysis of the ... [more ▼]

This paper deals with the application of statistical process control techniques based on principal component analysis to vibration-based damage diagnosis of structures. Principal component analysis of the sensor time-responses allows to extract principal directions (i.e. features) which define a subspace that is representative of the dynamics of the instrumented structure. Any change in the response of a single sensor will affect the subspace spanned by the complete sensor response set. It follows that the subspace corresponding to the current state of the structure can be compared to the subspace of the initial state of the structure, assumed to be healthy, in order to diagnose possible damage. Principal component analysis may also be performed for every potential subset of damaged sensors in order to identify the involved sensor, and, therefore, the damaged substructure. In this paper, the problem of structural damage detection is addressed in the case of environmental vibration testing. A direct application is presented for a test item submitted to random vibration testing by means of an electro-dynamic shaker. [less ▲]

Detailed reference viewed: 105 (3 ULg)
Full Text
See detailStructural damage diagnosis under changing environmental conditions
Yan, A. M.; Kerschen, Gaëtan ULg; De Boe, Pascal et al

in 7th International Conference on Motion and Vibration Control, Saint Louis, 2004 (2004)

A method is proposed to perform structural health monitoring under varying environmental and operational conditions. The method is based on principal component analysis (PCA) applied to a data set ... [more ▼]

A method is proposed to perform structural health monitoring under varying environmental and operational conditions. The method is based on principal component analysis (PCA) applied to a data set containing vibration characteristics identified during the monitoring of the structure. The advantage of the method is that it does not require the measurement of environmental parameters that are taken into account as embedded variables. As the influence of environmental effects may be effectively eliminated, the residual error of the PCA prediction model remains small if the structure is healthy, and increases significantly when structural damage occurs. Novelty analysis on the residual errors provides a statistical indication of damage. The PCA-based damage detection method is illustrated using experimental data. It will also be shown that when the relationship between the vibration characteristics becomes nonlinear, PCA is advantageously replaced by one of its nonlinear generalizations. [less ▲]

Detailed reference viewed: 53 (0 ULg)
Full Text
Peer Reviewed
See detailLa critique heideggérienne de la philosophie de la religion (Windelband, Rickert, Troeltsch)
Dewalque, Arnaud ULg

in Horizons philosophiques (2004), 14(2), 105-127

This paper presents Heidegger’s courses on religion (1920-21) as a criticism of axiological philosophy. It shows that the neokantian conception of “holy”, “history” and “divinity” involves the theoretical ... [more ▼]

This paper presents Heidegger’s courses on religion (1920-21) as a criticism of axiological philosophy. It shows that the neokantian conception of “holy”, “history” and “divinity” involves the theoretical problem of the correlation between validity and reality. Reading this problem as the background of Heidegger’s own position reveals that : 1. the heideggerian conceptuality (world, significativity, historicity) makes sense in opposition to the axiological one (object, value, validity) ; 2. the methodological key of this opposition lies in the principle of “formal indication”, wich also governs Heidegger’s conference “Phenomenology and theology” (1927). [less ▲]

Detailed reference viewed: 112 (6 ULg)
Full Text
Peer Reviewed
See detailLearner Support in the Formasup degree: variety as a key feature and close coaching to drive innovation
Poumay, Marianne ULg

in Supporting the Learner in Distance Education and E-Learning (2004)

Detailed reference viewed: 17 (2 ULg)
Full Text
Peer Reviewed
See detailDetection of moulds growing on building materials by gas sensor arrays and pattern recognition
Kuske, Martyna; Padilla, M.; Romain, Anne-Claude ULg et al

in Technical digest of eurosensors : proceedings (2004)

This work explores the detection of moulds growing in different building materials by using a metal oxide sensor array Four mould species have been considered. Pattern Classification provides ... [more ▼]

This work explores the detection of moulds growing in different building materials by using a metal oxide sensor array Four mould species have been considered. Pattern Classification provides classification rates on the order of 80-90% for different species. Drift degrades slightyl these values subsequent test four months later. [less ▲]

Detailed reference viewed: 31 (4 ULg)
Full Text
See detailNonlinear energy pumpin: A new paradigm for vibration isolation
Vakakis, Alexander F.; McFArland, D. Michael; Kerschen, Gaëtan ULg et al

in 3rd China-Japan US Symposium on Health Mondial and Control of Structures, Dalian, 2004 (2004)

We discuss passive nonlinear energy pumping from a linear (main) mechanical structure to a weakly coupled, local, passive nonlinear energy sink (NES). We show that the NES can be designed to effectively ... [more ▼]

We discuss passive nonlinear energy pumping from a linear (main) mechanical structure to a weakly coupled, local, passive nonlinear energy sink (NES). We show that the NES can be designed to effectively absorb vibrational energy from the main structure in a one-way, irreversible fashion. We demonstrate the occurrence of pumping cascades, where an appropriately designed NES passively extracts energy sequentially from a number of modes of the main (linear) structure, interacting individually with each mode before moving to the next. Experimental results confirm our theoretical findings. The applications of the nonlinear energy pumping phenomenon to the problem of vibration and shock isolation will be discussed. [less ▲]

Detailed reference viewed: 26 (1 ULg)
Full Text
See detailProper Orthogonal modes for the characterisation of nonlinear dynamic systems
Kerschen, Gaëtan ULg; Lenaerts, Vincent; Golinval, Jean-Claude ULg et al

in Euromech Colloquim on Nonlinear Modes of Vibrating Systems, Frejus, 2004 (2004)

Modal analysis is extensively used for the analysis and design of structures. However, a major concern for structural dynamicists is that its validity is limited to systems showing a linear behaviour. New ... [more ▼]

Modal analysis is extensively used for the analysis and design of structures. However, a major concern for structural dynamicists is that its validity is limited to systems showing a linear behaviour. New developments have thus been proposed in order to tackle nonlinear systems among which the theory based on the nonlinear normal modes is indubitably the most appealing. In this study, a different approach is adopted and the modes extracted from the proper orthogonal decomposition are considered for the characterization of nonlinear systems. [less ▲]

Detailed reference viewed: 31 (2 ULg)
Full Text
See detailSensor Validation for On-line Vibration Monitoring
Kerschen, Gaëtan ULg; De Boe, Pascal; Golinval, Jean-Claude ULg et al

in 2nd European Workshop on Structural Health Monitoring, Munich, 2004 (2004)

For a reliable on-line vibration monitoring of structures, it is necessary to have accurate sensor information. However, sensors may sometimes be faulty or may even become unavailable due to failure or ... [more ▼]

For a reliable on-line vibration monitoring of structures, it is necessary to have accurate sensor information. However, sensors may sometimes be faulty or may even become unavailable due to failure or maintenance activities. The problem of sensor validation is therefore a critical part or structural identification. The objective of the present study is to present a procedure based on principal component analysis, which is able to perform detection, isolation and reconstruction of a faulty sensor. Its e ciency is assessed using an experimental application. [less ▲]

Detailed reference viewed: 33 (1 ULg)
Full Text
See detailPassive energy transfer and dissipation for isolation from transcient broadband disturbances
Kerschen, Gaëtan ULg; McFarland, D. Michael; Kowtko, J. et al

in US-Korea Joint Seminar/Workshop on Smart Structures Technologies, Seoul, 2004 (2004)

We discuss passive nonlinear energy pumping from a linear (main) mechanical structure to a weakly coupled, local, passive nonlinear energy sink (NES). We show that the NES can be designed to effectively ... [more ▼]

We discuss passive nonlinear energy pumping from a linear (main) mechanical structure to a weakly coupled, local, passive nonlinear energy sink (NES). We show that the NES can be designed to effectively absorb vibrational energy from the main structure in a one-way, irreversible fashion. We demonstrate the occurrence of pumping cascades, where an appropriately designed NES passively extracts energy sequentially from a number of modes of the main (linear) structure, interacting individually with each mode before moving to the next. Experimental results confirm our theoretical findings. The applications of the nonlinear energy pumping phenomenon to the problem of vibration and shock isolation will be discussed [less ▲]

Detailed reference viewed: 18 (1 ULg)
Full Text
Peer Reviewed
See detailLa portée du témoignage de Pausanias sur les cultes locaux
Pirenne-Delforge, Vinciane ULg

in Mélanges de l'Ecole Française de Rome. Antiquité (2004)

Detailed reference viewed: 15 (4 ULg)
Full Text
Peer Reviewed
See detail« Cet obscur objet du désir ». La nudité féminine entre Orient et Grèce
Pirenne-Delforge, Vinciane ULg; Bonnet, Corinne

in Mélanges de l'École Française de Rome. Antiquité (2004), 116

Detailed reference viewed: 294 (7 ULg)
Full Text
Peer Reviewed
See detailQuelques réflexions méthodologiques à propos des enquêtes internationales dans le domaine de l'éducation
Monseur, Christian ULg; Demeuse, Marc

in Politiques d'Education et de Formation : Analyses et Comparaisons Internationales (2004), 11(2), 37-54

Detailed reference viewed: 13 (2 ULg)
Full Text
Peer Reviewed
See detailFlexibility and Security : What forms of Political Regulation ?
Nachi, Mohamed ULg

in Transfer. European Review of Labour and Research (2004), 10(2), 300-318

The article examines the strengths and weaknesses of the concept of ‘flexicurity’, calling into question the tendency of the contemporary cultural imagination to regard flexibility as a framework for the ... [more ▼]

The article examines the strengths and weaknesses of the concept of ‘flexicurity’, calling into question the tendency of the contemporary cultural imagination to regard flexibility as a framework for the expression of individual freedom. It then describes a range of possible policy options, in relation to the market, in the perspective of combining flexibility of labour and security of persons. Tree major options emerge: the ‘procedural’, the ‘neo-substantive’ and the ‘partnership’ options. As a conclusion, this article comes out in favour of different policy which would alter the framework for public intervention. It specially underlines the need for a ‘flexible’ and ‘decentred’ Welfare State, capable of supporting and encompassing forms of regulation emanating from civil society, in particular – but not exclusively – from the social partners. [less ▲]

Detailed reference viewed: 39 (6 ULg)
Full Text
Peer Reviewed
See detailThe morality in/of compromise: some
Nachi, Mohamed ULg

in Social Science Information/Information sur les sciences sociales (2004), 43(2), 291-305

This article aims to highlight the position occupied by compromise in the field of ethics. The argument is set out in two stages. First, the author attempts to clarify the contours of compromise by ... [more ▼]

This article aims to highlight the position occupied by compromise in the field of ethics. The argument is set out in two stages. First, the author attempts to clarify the contours of compromise by treating it as both a procedure or process of conflict resolution and a goal or ‘‘solution’’ to be achieved. In the second stage, he examines the distinction that could be made between ‘‘morality in compromise’’ and ‘‘morality of compromise’’, so as to measure its import and show how compromise not only contains elements specific to morality as a system but can also be a form of morality in itself. [less ▲]

Detailed reference viewed: 20 (1 ULg)
Full Text
Peer Reviewed
See detailLe compromis, rationalité et valeur. Esquisse d’une approche sociologique
Nachi, Mohamed ULg

in Social Science Information/Information sur les sciences sociales (2004), 43(2), 307-330

The authors propose a reflection on the status of compromise in European sociological tradition, and more particularly in two classical authors, Durkheim and Weber, as well as in several contemporary ... [more ▼]

The authors propose a reflection on the status of compromise in European sociological tradition, and more particularly in two classical authors, Durkheim and Weber, as well as in several contemporary authors who follow in Weber’s footsteps. After having noted the absence of any reference to the idea of compromise in Durkheim’s work, they posit that it is nevertheless possible to detect the presence of compromise as an implicit category in Weber’s writings, notably through his distinction between different ethics. While it is explicitly present in the contemporary authors examined, the concept is related to the different proceduralization theories found in Habermas, Crozier, Sainsaulieu and Reynaud. [less ▲]

Detailed reference viewed: 34 (2 ULg)
Full Text
Peer Reviewed
See detailIntroduction. Dimensions du compromis : Arguments pour la constitution d’une théorie du compromis
Nachi, Mohamed ULg

in Social Science Information/Information sur les sciences sociales (2004), 43(2), 131-143

Detailed reference viewed: 38 (3 ULg)
Full Text
Peer Reviewed
See detailVEGF Concentrations Levels in Bovine Ovulatory Follicles after Prostaglandin Treatment
Comin, Antonella; Maiero, Stefano; Furlan, Valentin et al

in Journal of animal and veterinary advances (2004), 3

Detailed reference viewed: 6 (0 ULg)
Full Text
See detailProposition d’une méthode d’inventaire « sylvicole » pour le diagnostic post-perturbation des hêtraies wallonnes touchées par la « maladie du hêtre »
Huart, Olivier; Lejeune, Philippe ULg; Lemoine, Nathalie et al

Learning material (2004)

L’objectif de la méthode d’inventaire « sylvicole » proposée est de fournir au gestionnaire un outil relativement simple et fiable qui lui permette d’acquérir une meilleure connaissance de l’état des ... [more ▼]

L’objectif de la méthode d’inventaire « sylvicole » proposée est de fournir au gestionnaire un outil relativement simple et fiable qui lui permette d’acquérir une meilleure connaissance de l’état des peuplements feuillus irréguliers, en particulier après l’avènement de la « maladie du hêtre » survenue en 1999 en Wallonie. Celle-ci a causé d’importants dégâts au sein des hêtraies d’Ardenne et de Gaume, allant jusqu’à bouleverser profondément le faciès de certaines hêtraies. Dans ce contexte, l’accent a été mis sur l’évaluation des perspectives sylvicoles de chaque parcelle (ou compartiment), essentiellement avec un objectif d’estimation de l’état sanitaire des arbres et de planification d’interventions sylvicoles les mieux adaptées à l’état des peuplements. La méthode proposée est basée sur la réalisation d’un inventaire par échantillonnage permettant de collecter une information complète, très utile à une gestion sylvicole relativement fine des peuplements feuillus. Une procédure de cartographie thématique des différents paramètres relevés sur le terrain ou issus de requêtes de l’utilisateur a également été développée. Le présent document décrit les modalités de mise en oeuvre ainsi que les possibilités d’exploitation de la méthode d’inventaire proposée. [less ▲]

Detailed reference viewed: 58 (8 ULg)