Publications ORBi OA
Bookmark and Share    
Full Text
Peer Reviewed
See detailClinching joining system: validation of numerical models
Pietrapertosa, C.; Zhang, Lihong ULg; Habraken, Anne ULg et al

in Brucato, V. (Ed.) Proceedings of the 6th International ESAFORM Conference on Material Forming (2003)

The clinching process, also known as “press joining”, is a mechanical joining technique for sheet metal. Its basic principle is to clamp together several metal sheets by an impact extrusion between a ... [more ▼]

The clinching process, also known as “press joining”, is a mechanical joining technique for sheet metal. Its basic principle is to clamp together several metal sheets by an impact extrusion between a punch and a die. The joint is formed by a localized cold plastic deformation. Forming is used as a joining method. Within the context of this research, University of Liège is developing numerical models, with the FEM code LAGAMINE, that simulate the clinching process. On the other hand, shear tests on simple joints with one or two clinches were realized and their behaviour is reproduced numerically with LAGAMINE. This work opens the way to the analytical formulation of the behaviour of clinched joints. The article will focus on comparisons between experiments and numerical simulations. First, the identification of model parameters will be explained. Then, the predicted failure modes will be analysed by comparison with the xperiments. [less ▲]

Detailed reference viewed: 86 (4 ULg)
Full Text
Peer Reviewed
See detailManaging Pests : consumers and commitments: The case of apple and pear growers in Belgium's Lower Meuse Region
Collet, Eric; Mormont, Marc ULg

in Environment & Planning A (2003), 35(3), 413-427

The authors analyse the construction of a seed fruit market. The conventional market had led to the 'anonymousness' of the fruit and to disconnected temporalities. The process needs new types of ... [more ▼]

The authors analyse the construction of a seed fruit market. The conventional market had led to the 'anonymousness' of the fruit and to disconnected temporalities. The process needs new types of coordination and components within the common information channels and actors' network. It also needs the construction of a new contract between producers and consumers, that the conventional market is unable to allow. Producers are experimenting with direct contact with the final consumer to find ways of allowing it. The fruit is replaced in the subject's experience of the final consumer and in the grower's story. The grower's story deals with managing pests, consumers, and commitments through a harmless action: eating a pear or an apple. [less ▲]

Detailed reference viewed: 59 (15 ULg)
Full Text
See detailLa sous-traitance internationale : questions choisies
Wautelet, Patrick ULg

in Commisison droit et vie des affaires (Ed.) La sous-traitance (2003)

In this paper, a general overview is given of the legal problems arising in the context of cross-border subcontracting operations. Particular attention is paid to the difficulties arising out of the fact ... [more ▼]

In this paper, a general overview is given of the legal problems arising in the context of cross-border subcontracting operations. Particular attention is paid to the difficulties arising out of the fact that the sub-contracting agreement is intertwined with the main contracting agreement [less ▲]

Detailed reference viewed: 367 (11 ULg)
Full Text
Peer Reviewed
See detailNumerical shear tests for different elasto-plastic laws
de Montleau, P.; Duchene, Laurent ULg; Flores, Paulo et al

in Onate, E.; Owen, D. R. J. (Eds.) Proceedings of the VII International Conference on Computational Plasticity (COMPLAS 2003) (2003)

This paper presents the numerical simulation of a cyclic simple shear test. The blank tested is a high strength steel sheet for which we use three different constitutive plastic laws derived from Teodosiu ... [more ▼]

This paper presents the numerical simulation of a cyclic simple shear test. The blank tested is a high strength steel sheet for which we use three different constitutive plastic laws derived from Teodosiu's model. These laws take into account respectively isotropic, kinematic and mixed isotropic-kinematic hardening. The goal of the paper is to provide a first numerical idea of the stress-strain path in the center of an experimental test sample. [less ▲]

Detailed reference viewed: 32 (6 ULg)
Full Text
Peer Reviewed
See detailUne méthode générique pour la classification automatique d'images à partir des pixels
Marée, Raphaël ULg; Geurts, Pierre ULg; Wehenkel, Louis ULg

in Revue des Nouvelles Technologies de l'Information (2003), 1

Dans cet article, nous évaluons une approche générique de classification automatique d'images. Elle repose sur une méthode d'apprentissage récente qui construit des ensembles d'arbres de décision par ... [more ▼]

Dans cet article, nous évaluons une approche générique de classification automatique d'images. Elle repose sur une méthode d'apprentissage récente qui construit des ensembles d'arbres de décision par sélection aléatoire des tests directement sur les valeurs basiques des pixels. Nous proposons une variante, également générique, qui réalise une augmentation fictive de la taille des échantillons par extraction et classification de sous-fenêtres des images. Ces deux approches sont évaluées et comparées sur quatre bases de données publiques de problèmes courants: la reconnaissance de chiffres manuscrits, de visages, d'objets 3D et de textures. [less ▲]

Detailed reference viewed: 112 (17 ULg)
Full Text
Peer Reviewed
See detailUnimolecular Dissociation of Halogenobenzene Cations by Phase space Theory.
Gridelet, E.; Lorquet, Jean-Claude ULg; Locht, Robert ULg et al

in Anton, J.; Cedrequist, H.; Larsson, M. (Eds.) et al 23rd International Conference on Photonic, Electronic and Atomic Collisions: Book of Abstracts. (2003)

The Orbiting Transition State version of the Phase Space Theory (PST) is used to calculate the KER distributions in the dissociation channel of X (X=I,Cl,Br)-loss from C6H5X+. The results are compared to ... [more ▼]

The Orbiting Transition State version of the Phase Space Theory (PST) is used to calculate the KER distributions in the dissociation channel of X (X=I,Cl,Br)-loss from C6H5X+. The results are compared to the experimental distribution and to that obtained by PST. [less ▲]

Detailed reference viewed: 42 (15 ULg)
Full Text
Peer Reviewed
See detailHow ergodic is the Fragmentation of the Pyridine Cation ? A Maximum Entropy Ananlysis
Gridelet, E.; Locht, Robert ULg; Lorquet, Andrée ULg et al

in Anton, J.; Cederquist, H.; Larsson, M. (Eds.) et al 23rd International Conference on the Photonic, Electronic and Atomic Collisions: Book of Abstracts. (2003)

The experimental KER and the statistical distributions are compared by the Maximum Entropy Method. An Ergodicity Index F(E) is defined to measure the phase space sampling efficiency. This is applied to ... [more ▼]

The experimental KER and the statistical distributions are compared by the Maximum Entropy Method. An Ergodicity Index F(E) is defined to measure the phase space sampling efficiency. This is applied to the KERD of C4H4+ cation produced by the C5H5N+ -> HCN+C4H4+ fragmentation path. In this particular case the F(E) is found to decrease steadily with increasing internal energy. [less ▲]

Detailed reference viewed: 31 (6 ULg)
Full Text
See detailAlgorithmes de contournement de barrières
Briquet, Cyril ULg

Master of advanced studies dissertation (2003)

GIS (Geographical Information Systems) bring an ever increasing range of solutions to decision makers seeking ever more accurate situational awareness in the issues they are facing. In particular, a GIS ... [more ▼]

GIS (Geographical Information Systems) bring an ever increasing range of solutions to decision makers seeking ever more accurate situational awareness in the issues they are facing. In particular, a GIS can provide a broad range of visual information resulting from computations that may be complex. These require to develop and implement efficient algorithms because of the massive amount of computations or data that are induced by the geographical nature of the processed data. The Urban and Rural Planning and Study Lab of University of Liege seeks to compute accessibility profiles for so-called "slow transport modes" in the Walloon Region. In this context, a relevant issue of computation of a socio-economical index based on spatial and population data is considered. The objective of this work is to modelize a problem of computation accessibility index, then solve it. The central part consists of the developement of a consistent and efficient algorithm chain to compute optimal shortest paths in geographical zones by avoiding barriers. The integration of the involved algorithms as well as the exploitation of intermediary results are fundemental aspects of the proposed solution. Two variants of the problem are modelized: DLOSP (Discrete Line-Of-Sight Paths, that does not take barriers into account) and DGSP (Discrete Geodesic Shortest Paths, that takes barriers into account). The detection and indexation of the barrieres, the refitting of the considered search space, the optimization of visibility requests and the computation of shortest paths constitute the main steps of the proposed algorithm chain. A distributed computing setup, naturally stemming from the structure of the problem itself, is briefly presented. [less ▲]

Detailed reference viewed: 69 (9 ULg)
Full Text
Peer Reviewed
See detailLa possible modification de la procédure de révision de la Constitution belge
Behrendt, Christian ULg

in Revue Française de Droit Constitutionnel (2003)

The article examines the question whether it is appropriate to alter the current amendment procedure of the Belgian constitution. Furthermore, the articles enquires into the possible design of a new ... [more ▼]

The article examines the question whether it is appropriate to alter the current amendment procedure of the Belgian constitution. Furthermore, the articles enquires into the possible design of a new amendment procedure. [less ▲]

Detailed reference viewed: 141 (17 ULg)
Full Text
See detailLiège-Paris 1848 : Littérature, féminisme et Révolution
Droixhe, Daniel ULg

in Bulletin de l'Académie Royale de Langue et de Littérature Françaises (2003), LXXXI(1-2), 41-49

Detailed reference viewed: 58 (4 ULg)
Full Text
Peer Reviewed
See detailCacophonie jurisprudentielle autour de la notion d’impôt
Rosoux, Géraldine ULg

in Revue de Jurisprudence de Liège, Mons et Bruxelles (2003)

The article analyzes a decision of the Belgian judicial Supreme Court concerning the concept of "tax", and emphasizes the conflict between this decision and the case-law of the Belgian constitutional Court

Detailed reference viewed: 82 (14 ULg)
Full Text
Peer Reviewed
See detailLeçons de l’éphémère. La Cour d’arbitrage et le "Renouveau’ électoral" – La Cour d’arbitrage et la suspension
Rosoux, Géraldine ULg

in Revue Belge de Droit Constitutionnel (2003)

The articles analyzes the electoral reform of 2003 and points out the competence of the Belgian constitutional Court to suspend legislative norms.

Detailed reference viewed: 59 (6 ULg)
Full Text
See detailDe "l'incapacité littéraire des Belges". Complexe national et contrefaçon
Droixhe, Daniel ULg; Ledain, O.

in Bertrand, Jean-Pierre; Biron, M.; Denis, Benoît (Eds.) et al Histoire de la littérature belge (1830-2000) (2003)

Detailed reference viewed: 34 (2 ULg)
Full Text
Peer Reviewed
See detailEvent-related potentials to emotional and neutral stimuli in alcoholism.
Hansenne, Michel ULg; Olin, Cecile; Pinto, Emmanuel ULg et al

in Neuropsychobiology (2003), 48(2), 77-81

Several studies have demonstrated that the emotional value of stimuli affects P300 amplitude. In the present study, the influence of alcohol-related stimuli in alcoholic patients was investigated ... [more ▼]

Several studies have demonstrated that the emotional value of stimuli affects P300 amplitude. In the present study, the influence of alcohol-related stimuli in alcoholic patients was investigated. Subjects were 10 alcoholic inpatients (3 female) and 10 age- and sex-matched controls. Eight alcohol-related and 8 neutral words served as stimuli in a visual oddball paradigm. Acohol-related words were targets (48 stimuli, 33%) and neutral words were standard stimuli (96 stimuli, 66%). Results showed that P300 amplitude for targets did not differ significantly between the two groups. However, P300 latency for targets as well as reaction time were significantly shorter in male alcoholic patients. In contrast, P300 latency was increased in female alcoholic patients but reaction time did not differ. These results suggest that male alcoholics process information linked to alcohol cues more rapidly than neutral cues, probably because a specific semantic network is activated in these patients. The decreased reaction time confirms the impulsive behavior frequently found in male alcoholism, as it has been described in type II alcoholism. Besides, the results imply that information processing was delayed in female alcoholic patients. Therefore this study demonstrates a gender-dependent impact of alcohol-related stimuli on information processing. [less ▲]

Detailed reference viewed: 51 (6 ULg)
Full Text
Peer Reviewed
See detailHarm avoidance is related to mismatch negativity (MMN) amplitude in healthy subjects
Hansenne, Michel ULg; Pinto, Emmanuel ULg; Scantamburlo, Gabrielle ULg et al

in Personality & Individual Differences (2003), 34(6), 1039-1048

Event-related potential (ERP) studies evidenced that some personality dimensions induced different controlled cognitive attitudes towards the processing of information. However, few data are available on ... [more ▼]

Event-related potential (ERP) studies evidenced that some personality dimensions induced different controlled cognitive attitudes towards the processing of information. However, few data are available on the possible relationships between personality and automatic attention or early sensory processing. In the present study the relationships between the mismatch negativity (MMN) and personality described by the Cloninger model of personality were investigated. Subjects were 32 healthy volunteers. The MMN was recorded with frequent stimuli tones of 1470 Hz, 70 dB and 40 ms duration, and target (20%) tones of 1470 Hz, 70 dB, 80 ms duration. The subjects completed a French version of the 226-item self-questionnaire TCI within the day following psychophysiological recording. The results showed that the HA dimension was negatively correlated with the MMN amplitude. The association was more present among women than men. No significant relationship existed between the other dimensions of personality and either the MMN amplitude or latency. These findings suggest that the MMN is related to the behavioral inhibition system (BIS), a fact which is consistent with clinical studies conducted on schizophrenia and anxiety disorders. In conclusion, this study suggests that personality dimensions induce different automatic attitudes towards the processing of information. (C) 2002 Published by Elsevier Science Ltd. [less ▲]

Detailed reference viewed: 102 (7 ULg)
Full Text
Peer Reviewed
See detailMismatch negativity is not correlated with neuroendocrine indicators of catecholaminergic activity in healthy subjects.
Hansenne, Michel ULg; Pinto, Emmanuel ULg; Scantamburlo, Gabrielle ULg et al

in Human Psychopharmacology (2003), 18(3), 201-5

The identification of the brain structures and neurotransmitters responsible for the generation and/or modulation of the mismatch negativity (MMN) may contribute to a clearer understanding of its ... [more ▼]

The identification of the brain structures and neurotransmitters responsible for the generation and/or modulation of the mismatch negativity (MMN) may contribute to a clearer understanding of its functional significance, and may have clinical implications. In this context, some findings suggest that the scalp-recorded MMN reflects activity from multiple neuronal ensembles within or in the immediate vicinity of the primary auditory cortex and with possible contribution from the frontal cortex. However, few data are available concerning the influence of neurotransmitter systems on the MMN. In this study, the relationship between both noradrenergic and dopaminergic systems and the MMN were investigated in 34 healthy volunteers. Noradrenergic and dopaminergic activities were assessed with the apomorphine and clonidine challenge tests. The results showed no significant relationship between either growth hormone (GH) responses to apomorphine or clonidine and the MMN amplitude or latency. Therefore, this study does not demonstrate the implication of dopaminergic and noradrenergic activities as assessed by GH response to apomorphine and clonidine for the generation and/or the modulation of the MMN. However, given the complexity of the central neurotransmitter systems, these results cannot be considered as definitive evidence against a relationship between dopaminergic and noradrenergic activity and the MMN. [less ▲]

Detailed reference viewed: 44 (2 ULg)
Full Text
Peer Reviewed
See detailA novel high efficiency, low maintenance, hydroponic system for synchronous growth and flowering of Arabidopsis thaliana.
Tocquin, Pierre ULg; Corbesier, Laurent; Havelange, Andrée ULg et al

in BMC Plant Biology (2003), 3(2), 302003

Background: Arabidopsis thaliana is now the model organism for genetic and molecular plant studies, but growing conditions may still impair the significance and reproducibility of the experimental ... [more ▼]

Background: Arabidopsis thaliana is now the model organism for genetic and molecular plant studies, but growing conditions may still impair the significance and reproducibility of the experimental strategies developed. Besides the use of phytotronic cabinets, controlling plant nutrition may be critical and could be achieved in hydroponics. The availability of such a system would also greatly facilitate studies dealing with root development. However, because of its small size and rosette growth habit, Arabidopsis is hardly grown in standard hydroponic devices and the systems described in the last years are still difficult to transpose at a large scale. Our aim was to design and optimize an up-scalable device that would be adaptable to any experimental conditions. Results: An hydroponic system was designed for Arabidopsis, which is based on two units: a seed-holder and a 1-L tank with its cover. The original agar-containing seed-holder allows the plants to grow from sowing to seed set, without transplanting step and with minimal waste. The optimum nitrate supply was determined for vegetative growth, and the flowering response to photoperiod and vernalization was characterized to show the feasibility and reproducibility of experiments extending over the whole life cycle. How this equipment allowed to overcome experimental problems is illustrated by the analysis of developmental effects of nitrate reductase deficiency in nia1nia2 mutants. Conclusion: The hydroponic device described in this paper allows to drive small and large scale cultures of homogeneously growing Arabidopsis plants. Its major advantages are its flexibility, easy handling, fast maintenance and low cost. It should be suitable for many experimental purposes. [less ▲]

Detailed reference viewed: 67 (7 ULg)
Full Text
Peer Reviewed
See detailAndropause and psychopathology: minor symptoms rather than pathological ones.
Delhez, Marie; Hansenne, Michel ULg; Legros, Jean-Jacques ULg

in Psychoneuroendocrinology (2003), 28(7), 863-74

This study examined the psychological symptomatology of men diagnosed with andropause and the association between calculated free testosterone (T) and depressed mood, anxiety and quality of life. Subjects ... [more ▼]

This study examined the psychological symptomatology of men diagnosed with andropause and the association between calculated free testosterone (T) and depressed mood, anxiety and quality of life. Subjects were 153 men, aged 50-70 years, who participated in a screening of andropause. Total testosterone, FSH, LH and SHBG levels were measured. Depressed mood was assessed with the Carroll Rating Scale, anxiety with the "anxiety-insomnia" dimension of the General Health Questionnaire, and quality of life with the World Health Organisation Quality of Life questionnaire. The results showed that levels of free T decreased with age, whereas FSH and LH increased. Carroll Rating Scale scores were higher among hypogonadal subjects, but the mean score was low and not pathological. A negative correlation was observed between severity of depression as assessed by the Carroll Rating Scale and free T levels. However, subjects with a significant score on this scale did not exhibit different free T levels compared to subjects with a non-significant depressive score. Anxiety and quality of life did not differ between hypogonadal and eugonadal subjects. The present study therefore suggests that andropause is not characterised by specific psychological symptoms, but may be associated with "depressive symptoms" that are not considered as pathological. [less ▲]

Detailed reference viewed: 42 (3 ULg)
Full Text
Peer Reviewed
See detailDistribution of surface carbon dioxide and air-sea exchange in the English Channel and adjacent areas
Borges, Alberto ULg; Frankignoulle, Michel

in Journal of Geophysical Research (2003), 108(C5),

In the present paper we report the distribution of the partial pressure of CO2 (pCO2) in surface waters along 13 transects in the English Channel, covering the four seasons. The spatial and temporal ... [more ▼]

In the present paper we report the distribution of the partial pressure of CO2 (pCO2) in surface waters along 13 transects in the English Channel, covering the four seasons. The spatial and temporal variability of pCO2 is controlled by a complex combination of primary production (from May to June), degradation of organic matter, temperature change, and freshwater inputs. Preliminary air-sea CO2 exchange computations suggest that the Channel is not a major sink of atmospheric CO2 and is probably neutral from the point of view of atmospheric coupling. This is mainly related to a relatively low export and/or burial of organic carbon and intense benthic calcification. [less ▲]

Detailed reference viewed: 19 (3 ULg)
Full Text
Peer Reviewed
See detailCarbon dioxide daily variations and atmospheric fluxes over the Great Bahama Bank using a novel autonomous measuring system
Frankignoulle, Michel; Biondo, Renzo ULg; Théate, Jean-Marie et al

in Caribbean Journal of Sience (2003), 39(3), 257-264

A novel autonomous measuring device that acquires the partial pressure of CO2 (pCO2) by equilibration and several other parameters is described. This device, the Floating Equilibrator System (FES) was ... [more ▼]

A novel autonomous measuring device that acquires the partial pressure of CO2 (pCO2) by equilibration and several other parameters is described. This device, the Floating Equilibrator System (FES) was tested in field conditions for the first time in the Great Bahama Bank, in December 2000. We successfully carried out two 24 h cycles in Norman’s Pond, one in front of the Caribbean Marine Research Centre (CMRC) and another one near Bock Cay. Over-saturation of CO2 with respect to atmospheric equilibrium was observed systematically at the three sites, although significantly more marked at Norman’s Pond. The higher values of pCO2 and atmospheric CO2 fluxes obtained at Norman’s Pond, than in the adjacent open waters of the Great Bahama Bank, suggest a comparatively stronger heterotrophy at Norman’s Pond. This is most likely related to the organic carbon inputs to the water column and sediments from the dense mangrove forest surrounding Norman’s Pond. The larger amplitude of pCO2 daily variations observed, during the Norman’s Pond 24 h cycles, is probably due to higher biological activity than in the adjacent open waters of the Great Bahama Bank. This is corroborated by a tentative estimation of Gross Primary Production based on simple computations. We speculate that calcification could also contribute to some extent to different amplitude of the pCO2 daily variations between the mangrove pond and the open waters of the Great Bahama Bank. [less ▲]

Detailed reference viewed: 28 (3 ULg)