L'approche individuelle de l'écologie comportementale de la truite commune Salmo trutta. Une nécessité pour la compréhension et la gestion des populations.

Conference given outside the academic context (2002)

L'amélioration de la qualité de l'alimentation bovine en vue de la réduction des émissions de méthane

Conference given outside the academic context (2002)

Mobilité durable et activités économiques : adéquation entre profils de mobilité et profil d’accessibilité des lieux

Conference given outside the academic context (2002)

La rééducation vocale

Conference given outside the academic context (2002)

"L'enseignement du FLES en question"

Conference given outside the academic context (2002)

Les résultats de l'enquête Pisa 2000 : Au-delà des performances des élèves, un système éducatif se profile.

Conference given outside the academic context (2002)

Construction d'habitations en bois. Trois techniques différentes

Conference given outside the academic context (2002)

Le développement durable

Conference given outside the academic context (2002)

Présentation des résultats de l'étude portant sur les pratiques et les attitudes des jeunes francophones par rapport aux langues étrangères.

Conference given outside the academic context (2002)

Optimiser l'expression orale en travaillant sur les stratégies de communication (2nde partie).

Conference given outside the academic context (2002)

"L'enseignement du FLES en immersion"

Conference given outside the academic context (2002)

Le développement durable

Conference given outside the academic context (2002)

Médiations, institutions, cultures

Conference given outside the academic context (2002)

La fossilisation des langues chez la première génération d’immigrés

Conference given outside the academic context (2002)

A Robust FRF-based Technique for Model Updating

Conference given outside the academic context (2002)

Frequency Response Functions (FRFs) residues have been widely used in time to update Finite Element models. Major reasons for this is that FRFs are very sensitive to damping properties at resonance peaks ... [more ▼]

Frequency Response Functions (FRFs) residues have been widely used in time to update Finite Element models. Major reasons for this is that FRFs are very sensitive to damping properties at resonance peaks, local modes influence is included and no modal analysis is required. Nevertheless, it is well known that due to their nature, the frequency responses may change its order of magnitude very rapidly for small parameter or frequency changes. This situation may cause serious discontinuities in the topology of the objective function, causing the updating strategy to diverge or to find a local non-physical minimum. A primary tool for the correlation of FRFs is the Frequency Domain Assurance Criterion. This technique introduces the concept of frequency shift between the frequency response shapes of a reference model (the experimental structure) and a perturbed model (an initial non-updated FE model). Such a concept opens the way for using residues at different frequencies. For instance, in reference the residue is composed by point FRFs at anti-resonances. This paper introduces a general FRF-based model-updating technique, which is focused in using stable residues during the interactive optimization procedure. A benchmark case from the Cost F3 action is used to assess the goodness of the method compared to other well known methods. [less ▲]

Accelerated Fatigue Testing Methodology of Luminaires on Electro-Dynamic Shaker

Conference given outside the academic context (2002)

Gestion environnementale des affections respiratoires du cheval

Conference given outside the academic context (2002)

Isolement et caractérisation de sept lignées monosomiques d'addition de Gossypium australe F. Muell. sur G. hirsutum L.

Conference given outside the academic context (2002)

Les associations dans le système européen des comptes nationaux

Conference given outside the academic context (2001)

La valorisation de la betterave fourragère dans l'alimentation de la vache laitière et du bétail à l'engraissement

Conference given outside the academic context (2001)

Enrichissement en PUFA oméga 3 et CLA des produits des porcs et des volailles: mythe ou réalité.

Conference given outside the academic context (2001)

Mutations urbaines et développement durable : les surcoûts de la désurbanisation

Conference given outside the academic context (2001)

"Est-ce si difficile d'apprendre une langue étrangère est ?!?"

Conference given outside the academic context (2001)

Les cités-états de Haute Mésopotamie: aux origines de la civilisation urbaine

Conference given outside the academic context (2001)

Y a-t-il une censure dans l’information ?

Conference given outside the academic context (2001)

Lotissement périurbain et développement durable : les surcoûts collectifs

Conference given outside the academic context (2001)

SAFIR A software for modelling the behaviour of structure submitted to the fire

Conference given outside the academic context (2001)

L'alimentation des bovins Blanc Bleu Belge culards

Conference given outside the academic context (2001)

L'atelier du goût.

Conference given outside the academic context (2001)

Finite Element Model Updating of the Garteur SM-AG19 Structure

Conference given outside the academic context (2001)

This paper reports the procedure followed by the "LTAS-Vibrations et Identification des Structures" research group to generate a low order nite element (F.E.) model of the GARTEUR SM-AG19 structure ... [more ▼]

This paper reports the procedure followed by the "LTAS-Vibrations et Identification des Structures" research group to generate a low order nite element (F.E.) model of the GARTEUR SM-AG19 structure proposed as benchmark in the framework of the European COST Action F3 in structural dynamics. The model is made of beam elements, local inertia and rigid body elements. First, the correlation of the experimental data with the results of the F.E. model shows different levels of discrepancies. To perform local error detection, the size of the measured mode shape vectors is first expanded to the size of the F.E. eigenvectors. Model error localisation is based on the computation of residual strain energy due to errors in the constitutive equations. Updating parameters are then selected using eigenvalue sensitivity and local error analyses. The error localisation procedure is followed by the updating process in order to improve the accuracy of the FE models. The quality of the results is assessed in terms of accuracy of the response prediction to structural modifications. [less ▲]

Damage Localisation Using Principal Component Analysis of Distributed Sensor Array

Conference given outside the academic context (2001)

The spatial information given by the distributed sensors (e.g., piezoelectric laminates) can be used to forecast structural damage on localised critical spot. It is well known that a localised structural ... [more ▼]

The spatial information given by the distributed sensors (e.g., piezoelectric laminates) can be used to forecast structural damage on localised critical spot. It is well known that a localised structural damage with relative small amplitude does not affect significantly the modal response of the structure, at least at low frequencies. Nevertheless, a local de-lamination or electrode deterioration at the distributed sensor level will show significant changes on the response of the sensor by modifying its apparent electromechanical coupling. Assuming that the number of sensors is greater than the number of involved structural modes, a local structural damage, with relative small amplitude, will only affect a particular distributed sensor without affecting significantly the response of the others. By applying a principal component analysis (PCA) on the sensor time responses, it is possible to see that any change of one particular sensor electromechanical coupling factor will affect the subspace generated by the complete sensor response set. The subspace generated with the damaged structure can then be compared with the subspace of an initial state in order to diagnose damage or not. [less ▲]

Les révolutionnaires sortiront-ils du rang ? Les valeurs éducatives entre la famille et l'école

Conference given outside the academic context (2001)

Quelle relation entre le programme éducatif de l'Ecole, inscrit dans des textes légaux, et les valeurs éducatives prônées par les familles ? Comment comprendre les affrontements parfois vifs entre les ... [more ▼]

Quelle relation entre le programme éducatif de l'Ecole, inscrit dans des textes légaux, et les valeurs éducatives prônées par les familles ? Comment comprendre les affrontements parfois vifs entre les différents acteurs éducatifs ? Se pourrait-il que les interlocuteurs les plus exigeants sont ceux qui, dans leurs activités professionnelles, se sont déjà approprié le modèle scolaire d'éducation et de formation, et en ont perçu les contradictions et les limites ? [less ▲]

Qualité et production des produits agricoles

Conference given outside the academic context (2001)

Comment lire entre les lignes? Les secrets de l’interprétation

Conference given outside the academic context (2000)

Alimentation et fertilité en Blanc Bleu Belge

Conference given outside the academic context (2000)

"L'apport de la psychologie de l'apprentissage pour l'enseignement d'une langue seconde"

Conference given outside the academic context (2000)

"II: La langue"

Conference given outside the academic context (2000)

L’état du logement à Liège

Conference given outside the academic context (2000)

La pratique de l'alimentatin hivernale des bovins laitiers, ses buts, ses objectifs. Avantages de la mélangeuse distributrice, résultats obtenus sur le terrain

Conference given outside the academic context (2000)

Alimentation du taurillon Blanc Bleu Belge culard

Conference given outside the academic context (2000)

Les métaphores du temps en Egypte ancienne

Conference given outside the academic context (2000)

Les médias face aux mouvements sociaux

Conference given outside the academic context (2000)

La fonction paternelle dans la société contemporaine

Conference given outside the academic context (2000)

ARMAV Model Technique for System Identification and Damage Detection

Conference given outside the academic context (2000)

This paper presents an application of ARMAV models in the fields of system identification and damage detection. It is shown how to estimate the modal parameters as well as their uncertainties only on the ... [more ▼]

This paper presents an application of ARMAV models in the fields of system identification and damage detection. It is shown how to estimate the modal parameters as well as their uncertainties only on the basis of output measurements, simply assuming that the excitation is a zero-mean stationary Gaussian white noise. The uncertainties estimation can be used for damage detection. Knowing the modal parameters and their uncertainties, it is possible to assess whether changes of modal parameters are caused by e.g. a damage or simply by estimation inaccuracies. The identification and damage detection method is illustrated on the “Steel-Quake” benchmark proposed in the framework of COST Action F3 “Structural Dynamics”. This structure is used at the Joint Research Centre in Ispra (Italy) to test steel buildings performance during earthquakes. The obtained results indicate the effectiveness of the method in estimating modal characteristics and their uncertainties. [less ▲]

Le quarantième anniversaire de l’Orchestre Philharmonique de Liège

Conference given outside the academic context (2000)

Identification of Electromechanical Coupling in Piezo-Structures

Conference given outside the academic context (2000)

An identification method based on a structural model updating procedure may be used to improve the knowledge of a piezoelectric tested structure and to determine the coupling coefficients of the ... [more ▼]

An identification method based on a structural model updating procedure may be used to improve the knowledge of a piezoelectric tested structure and to determine the coupling coefficients of the piezoelectric material. This procedure starts with the modal analysis of the open-loop instrumented structure. Let the target modes be a subset of the model modes; a selection of sensor (generally accelerometers) locations is then performed by determining the smaller subset such that the H2 modal norm is as close as possible to the modal norm of the original full set. In most cases, experimental testing with the selected sensor set will give acceptable information to identify target modes. These data, coupled with electrical sensing at the piezoelectric element level, will then be used to perform modal analysis of the piezo-structure. A pole-residue development of the open-loop piezo-structure shows that conventional algorithms may be used to estimate the mechanical modal parameters and the electromechanical coupling matrix. The second step of the procedure is to perform model updating itself. The initial finite element piezoelectric model will be improved stiffness corrections to the global stiffness matrix.. The corrections are split in their mechanical and electromechanical contributions. It is then possible to separate mechanical modelling errors from electromechanical coupling errors. The problem becomes a classical model updating problem which may be solved using well established techniques. This will result not only in a model behaving like the measures, but also in an improved knowledge of the structure behaviour without loosing physical insight. From a numerical point of view, it will be shown that ill-conditioning inherent to the presence of piezoelectric elements presents some difficulties at different steps of the model correction procedure. A clamped-free plate instrumented with piezo-laminates is used to illustrate the model updating approach. The selection of measurement points, using the modal norm criteria, is also presented. Experimental identification data will then be used as inputs for the model correction procedure and the behaviour of the updated model will be compared with the initial model dynamics. [less ▲]

Modal identification in presence of noise using an optimization approach

Conference given outside the academic context (2000)

This paper deals with the problem of modal parameter identification when the measurements are perturbed by unknown but bounded noise. It is well known that the classical Total Least Square (TLS) solution ... [more ▼]

This paper deals with the problem of modal parameter identification when the measurements are perturbed by unknown but bounded noise. It is well known that the classical Total Least Square (TLS) solution is the most accurate one, but that it is quite sensitive to data perturbations. This feature is a big drawback since it is desirable that the estimated modal parameters should not vary when perturbations on measurements change. An optimisation technique suited to so-called second-order cone programs [2] is proposed and tested. This method sets the identification problem in a MIN-MAX formulation [1] and uses an iterative interior-point primal-dual potential reduction algorithm [3, 4]. The residual error is first maximised over the set of possible perturbations leading thus to a worst-case residual error. Then, it is minimised over the set of identification variables. This procedure guarantees the robustness of the solution in the sense that no perturbation of the considered set could make the residual error bigger. This robustness is obtained to the detriment of an absolute accuracy. A good compromize between robustness and accuracy may be found through the prior resolution of the associate TLS problem. The optimisation program is tested in the case of a clamped-free beam for which closed-form solutions are available. A comparison with the TLS solution is also performed. [less ▲]

Principales helminthoses digestives chez les carnivores domestiques et leur traitement

Conference given outside the academic context (2000)

Les principales helminthoses chez les carnivores domestiques et leur traitement

Conference given outside the academic context (2000)

Les principales helminthoses chez les carnivores domestiques et leur traitement

Conference given outside the academic context (2000)