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See detailUn peuple et ses pères. Lubumbashi entre démodernisation et postmodernité. Approche des associations locales de type ONG
Poncelet, Marc ULg; Pirotte, Gautier ULg

in Charlier, Jean-Emile; Moens, Frédéric (Eds.) Modernité et recomposition locale du sens (1999)

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See detailPolarimetry and Spectropolarimetry of a Sample of Broad Absorption Line Quasars
Lamy, H.; Hutsemekers, Damien ULg

in Structure and Kinematics of Quasar Broad Line Regions. ASPC 175 (1999)

Optical polarimetric and spectropolarimetric observations of a sample of broad absorption line QSOs were recently carried out with the 3.6m telescope and EFOSC1 in La Silla, Chile. Some preliminary ... [more ▼]

Optical polarimetric and spectropolarimetric observations of a sample of broad absorption line QSOs were recently carried out with the 3.6m telescope and EFOSC1 in La Silla, Chile. Some preliminary results are presented here with emphasis on interesting correlations between polarization and other quantities characterizing the optical spectra of the objects. [less ▲]

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See detailHST/GHRS ultraviolet spectroscopy and model diagnostics of the Jovian aurora.
Gérard, Jean-Claude ULg; Dols, V.; Gustin, Jacques ULg et al

in Bulletin of the American Astronomical Society (1999)

A model coupling a detailed synthetic spectrum of the H_2 Lyman and Werner band systems with an electron energy degradation code is applied to the analysis of 7 GHRS spectra of the 1200-1700 { Angstroms ... [more ▼]

A model coupling a detailed synthetic spectrum of the H_2 Lyman and Werner band systems with an electron energy degradation code is applied to the analysis of 7 GHRS spectra of the 1200-1700 { Angstroms} region obtained with a ~ 5 { Angstroms} resolution at various locations in the north and south Jovian aurora. The observed color ratios indicate that the characteristic energy of the assumed initial Maxwellian distribution ranges between 17 and 40 keV. A clear signature of acetylene is observed near the absorption peaks at 1520, 1480 and 1440 { Angstroms}. The C_2H_2 column overlying the emission peak varies from 0.02 to 0.2 of the methane column. A better fit is obtained for some spectra when ethane absorption is added. The changing mixing ratios relative to methane are attributed to perturbations by heat released by the fast electron thermalization and/or perturbations to the hydrocarbon chemistry resulting from the production of H atoms by the aurora. A spectrum of the Io magnetic footprint and its trailing tail shows ultraviolet color and hydrocarbon absorption charateristics quite similar to some of the main oval spectra. This observation implies that the electrons of the Io flux tube are energized to a few tens of keV, similar to the electron precipitated in the main ovals and polar caps. Echelle spectra between 1216 and 1220 { Angstroms} at 0.07 { Angstroms} resolution are also compared with the model best fitting the closely spaced in time mid-resolution spectrum. It is found that the effective H_2 rovibrational temperature associated with the Echelle spectra is significantly higher than predicted by the model. A steep temperature gradient near the methane homopause due to large heating by auroral precipitation is a plausible explanation for this difference. We acknowledge funding by NASA and the PRODEX program of the European Space Agency. [less ▲]

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See detailChanges in respiratory mechanics measured by IOS during the first day of life in calves
Uystepruyst, Ch; Reinhold, P.; Coghe, J. et al

in Proceedings: 17th Symposium of the Comparative Respiratory Society (1999)

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See detailMolecular and atomic hydrogen in the environment of hot, massive stars
St-Louis, N.; Gervais, S.; Morel, Thierry ULg et al

in Wolf-Rayet Phenomena in Massive Stars and Starburst Galaxies (1999)

Not Available

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See detailHST/STIS images of UV auroral footprints from Io, Europa, and Ganymede.
Clarke, J. T.; Ajello, J.; Ballester, G. E. et al

in Bulletin of the American Astronomical Society (1999)

Ultraviolet images of Jupiter's aurora have been obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) since September 1997 with much higher sensitivity than ... [more ▼]

Ultraviolet images of Jupiter's aurora have been obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) since September 1997 with much higher sensitivity than earlier cameras. Higher sensitivity permits shorter exposures, freezing Jupiter's rotation and providing the highest angular resolution obtained to date. This combination of sensitivity and resolution has revealed new emissions from the magnetic footprints of Io, Europa, and Ganymede, which will be reported and discussed. Io's auroral footprint, while well studied with earlier cameras, appears highly extended at a low brightness in the wake or plasma flow direction. Ganymede's auroral footprint emission is now well established from the repeated appearance of this feature under the magnetic field trace of Ganymede, and there is initial evidence for auroral emission at Europa's magnetic footprint. Ganymede's auroral footprint appears consistently equatorward of the main auroral oval, which clearly constrains the main oval auroral currents to originate from beyond about 20 R_J. The observation that the main oval emissions are observed to corotate with Jupiter's magnetic field further constrains the origin of these currents to be within about 30 R_J, so that the source region for the main oval auroral is now fairly well constrained to a region in Jupiter's middle magnetosphere and within the current sheet. This work was supported by NASA under grant GO-7308.01-96A to the University of Michigan. [less ▲]

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See detailUn dictionnaire des verbes néo-égyptiens
Winand, Jean ULg

in Reineke, W. (Ed.) Wörterbücher und Textcorpus (1999)

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See detailTracing techniques as a contribution to karstology : past experiences, new directions.
Meus, Philippe; Ek, Camille ULg

in Andrea, B. (Ed.) Contribución del Estudio de las Cavidades kársticas al Conocimiento geológico (1999)

During a long period, tracer tests aimed exclusively to define water catchment areas in karst basins. Recent developments in the methodology and in the technique itself have largely increased the ... [more ▼]

During a long period, tracer tests aimed exclusively to define water catchment areas in karst basins. Recent developments in the methodology and in the technique itself have largely increased the potentialities of understanding karst flow mechanisms : use of boreholes as injection or measuring points, progress in tracer selection and detection, introduction of continuous monitoring... This paper emphasizes the parallelism between the evolution of the tracing technique and the knowledge of karst. [less ▲]

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See detailJovian thermal structure inferred from the energy degradation of auroral electrons.
Grodent, Denis ULg; Gérard, Jean-Claude ULg; Waite, J H, Jr

in Bulletin of the American Astronomical Society (1999)

Not Available

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See detailSurveys with a 4 m Liquid Mirror Telescope
Jean, C.; Claeskens, Jean-François ULg; Surdej, Jean ULg

in Morgant, Faffaella; Couch, Warrick J. (Eds.) Looking Deep in the Southern Sky (1999)

We describe an international project of construction and operation of a 4 m Liquid Mirror Telescope (LMT) led by E. Borra. A LMT, whose main advantage is its very low cost, is particularly well suited for ... [more ▼]

We describe an international project of construction and operation of a 4 m Liquid Mirror Telescope (LMT) led by E. Borra. A LMT, whose main advantage is its very low cost, is particularly well suited for the search and study of gravitational lenses, type Ia supernovae, faint nearby red, brown and white dwarfs, halo stars with high proper motions and, more generally, all variable phenomena like quasars, variable stars, micro-lensing effects, etc. [less ▲]

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See detailVoltage stability analysis of multi-level load tap changer systems
Rousseaux, Patricia ULg; Van Cutsem, Thierry ULg

in Proceedings of the 13th Power System Computation Conference (PSCC) (1999)

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See detailAdaptation of the European crop growth monitoring system to the Belgian conditions.
Tychon, Bernard ULg; Buffet, D.; Dehem, Didier et al

in Donatelli, Marcello; Stockle, Claudio; Villalobos, Francisco (Eds.) et al International symposium on modelling cropping systems Lleida, 21-23 june, 1999, Book of proceedings (1999)

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See detailUse of mineralization kinetics to estimate the agricultural value of a compost incorporated into a vineyard in Luxembourg.
Weinzaepflen, Emmanuelle; Tychon, Bernard ULg; Godden, B.

in Warman, P. R.; Taylor, B. R. (Eds.) Proceedings of the International composting symposium (ICS'99) (1999)

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See detailTranscription factor, nuclear factor-kB, activity in bronchial epithelial cells of RAO horses
Bureau, Fabrice ULg; Fievez, Laurence ULg; Kirschvink, Nathalie et al

in Proceedings: 17th Symposium of the Comparative Respiratory Society (1999)

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See detailCharacterization of menin from leucocytes of normal and men 1-affected individuals
Poncin, J.; Closset, J.; Legros, J.-J. et al

in 7th International workshop on Multiple Endocrine Neoplasia - Abstract book (1999)

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See detailPresentation of Fondation Universitaire Luxembourgeoise activities in Remote sensing
Tychon, Bernard ULg

in Catalogue of presentations Earth observation for environmental monitoring Information Day (1999)

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See detailEffects of growth hormone therapy on bone metabolism in patients with adult-onset : a 2-year open randomized controlled multicentre trial
Bex, M.; Abs, R.; Maiter, D. et al

in The 6th International Pituitary Congress - Abstract book (1999)

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See detailDual Magnetodynamic Formulations and Their Source Fields Associated with Massive and Stranded Inductors
Dular, Patrick; Kuo-Peng, P.; Geuzaine, Christophe ULg et al

in Proceedings of the 12th COMPUMAG Conference on the Computation of Electromagnetic Fields (1999)

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See detailUse of graphite chromium cast iron in hot strip mill
Lecomte-Beckers, Jacqueline ULg; Terziev, Luben; Breyer, Jean-Pierre et al

in Proceedings of the Conference SARUC 99 - The Southern African Roll Users Conference (1999)

In this paper, we will point out the good properties of the new material called graphitic chromium iron and show that it can lead to an optimised compromise between oxidation, wear and thermal behaviour ... [more ▼]

In this paper, we will point out the good properties of the new material called graphitic chromium iron and show that it can lead to an optimised compromise between oxidation, wear and thermal behaviour allowing its use as work roll in the last stands of the finishing section of HSM. We will also summarise the results of a study aimed to examine the graphite formation conditions in high chromium iron and the effect of an austenite de-stabilisation heat treatment on the graphitisation. The amount and volume of free graphite may be dramatically influenced by a suitable heat treatment, which increases the thermal properties. Some manufacturing problems associated with the residual stresses of that new grade will also be explained. [less ▲]

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See detailIntegration of recrystallisation model coupled with an elasto-visco-plastic law - Experimental tests and calibration of this model
Charles, J. F.; Habraken, Anne ULg; Lecomte-Beckers, Jacqueline ULg

in Proceedings of the 2nd ESAFORM Conference on Material Forming (1999)

The recrystallisation model is based on the model developed by Kopp [1,2]. This model is implemented in our finite element code "lagamine" and is coupled with a thermomechanical elasto-visco-plastic law ... [more ▼]

The recrystallisation model is based on the model developed by Kopp [1,2]. This model is implemented in our finite element code "lagamine" and is coupled with a thermomechanical elasto-visco-plastic law. It assumes that each integration point in the mesh is represented by a number of sub-structures with a different volumic recrystallised fraction. In order to be able to calibrate such a model, we need to perform a lot of experimentals tests. Hot compression tests on small cylinder at different temperatures and strain rates are made till strain level from 0.1 up to 0.7. The compressed cylinders are quenched after the tests. A metallographic study of the quenched cylinders gives the recrystallised fraction function of the strain, the strain rate and temperature. So experimental, numerical and metallographic studies of hot compression tests aim the definition of an accurate predictive thermo-mechanic metallurgical model able to stimulate forging processes. [less ▲]

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See detailSustained NF-kB activity after removal of the etiologic agent in an animal model of asthma
Bureau, Fabrice ULg; Bonizzi, G.; Kirschvink, Nathalie et al

in Proceedings: 1999 International Conference of the American Thoracic Society (1999)

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See detailProposals for a modified beam finite element embedding the deformation of the cross section
Degée, Hervé ULg

in Proceedings of the SDSS '99 Conferences (Stability and Ductility of Steel Structures) (1999)

The correct modelling of some phenomena occurring in steel profiles requires a due account for the deformability of the cross section of the profile. Such phenomena are for example local buckling ... [more ▼]

The correct modelling of some phenomena occurring in steel profiles requires a due account for the deformability of the cross section of the profile. Such phenomena are for example local buckling, distortional buckling, lateral buckling, distortional torsion…Different numerical methods are available to study these behaviours (classical finite strips, spline finite strips, plate finite elements, generalised beam theory, special beam elements…). A first part of the paper consists in a qualitative comparative analysis of these methods. In a second part, a new method is proposed, that can be used essentially for the analysis of structures made of members subject to local buckling, or any other phenomenon including a distortion of the cross section. It consists in the integration of the deformability of the cross section directly in a beam element, by enriching the displacement field. Some results related to local buckling, obtained with this modified beam element, are presented. [less ▲]

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See detailThymic insulin-related polypeptides: role in T cell selection and in central self-tolerance of the insulin family
Kecha, Ouafae; Brilot, Fabienne; Martens, Henri ULg et al

in The Endocrine Society (Ed.) Proceedings of the 81st Annual Meeting of the Endocrine Society (1999)

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See detailDual Magnetodynamic Formulations and their Source Fields associated with Stranded Inductors
Dular, Patrick ULg; Kuo-Peng, P.; Geuzaine, Christophe ULg et al

in Proceedings of the 12th Conference on the Computation of Electromagnetic Fields, COMPUMAG 1999 (1999)

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See detailOn the necessity to use three-dimensional groundwater models for describing impact of drought conditions on streamflow regimes
Dassargues, Alain ULg; Maréchal, J. C.; Carabin, Guy et al

in Hydrological Extremes : Understanding, Predicting, Mitigating (1999)

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See detailFeeding weaned pigs pellets or meal? Effects on performance, water intake and eating behaviour
Laitat, Martine ULg; Vandenheede, Marc ULg; Desiron, A. et al

in Proceedings of the 50th EAAP (1999)

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See detailUse of Multiple-trait Across Country Evaluation (MACE) procedures to estimate genetic correlations in dual purpose Austrian Simmental
Druet, Tom ULg; Sölkner, J.; Gengler, Nicolas ULg

in Book of Abstracts of the 50th Annual Meeting of the European Association for Animal Production (1999)

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See detailDetailed calibration of a deterministic transport model on multi-tracer tests: analysis and comparison with semi-analytical solutions
Haerens, B.; Brouyère, Serge ULg; Dassargues, Alain ULg

in Stauffer, F.; Kinzelbach, W.; Kovar, K. (Eds.) et al Calibration and Reliability in Groundwater Modelling Pre-published Proc. of ModelCARE99 (1999)

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See detailCartography of Microclimatic Zones Using InSAR DTM
Closson, Damien; Cornet, Yves ULg; Ozer, André ULg et al

in ESA (Ed.) Proc. FRINGE'99 Symposium (1999)

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See detailElastoplastic anisotropic model based on texture analysis to simulate steel sheet behavior
Duchene, Laurent ULg; Habraken, Anne ULg; Cescotto, Serge ULg

in 7th International Symposium on Plasticity (1999)

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See detailScale relativity in the solar system - A review and prospects
Hermann, Raphaël ULg

(1999)

We shall consider the scale-relativistic model for describing the behaviour of chaotic systems beyond the predictability horizon. Nondifferentiable mechanics will give us our main structure equation. We ... [more ▼]

We shall consider the scale-relativistic model for describing the behaviour of chaotic systems beyond the predictability horizon. Nondifferentiable mechanics will give us our main structure equation. We shall then apply it to get a model of the positions of planets and satellites in the solar system. Finally, we shall see how this method could be applied to the structure of the asteroid belt. [less ▲]

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See detailFacultative paedomorphosis in the Alpine newt, Triturus a. alpestris: feeding habits and habitat use in an Alpine lake
Denoël, Mathieu ULg; Joly, Pierre; Poncin, Pascal ULg

in Miaud, C.; Guyetant, G. (Eds.) Current Studies in Herpetology (1999)

Feeding habits and micro-habitat use were compared between metamorphs and paedomorphs in a population of the Alpine newt, Triturus a. alpestris in the French Alps. This population occupies a deep Alpine ... [more ▼]

Feeding habits and micro-habitat use were compared between metamorphs and paedomorphs in a population of the Alpine newt, Triturus a. alpestris in the French Alps. This population occupies a deep Alpine lake. The paedomorphs largely outnumbered the metamorphs. Whereas paedomorph diet was mainly composed of plankton, that of metamorphs was especially composed of larval and adult insects. The spatial use of the habitat also differed between the two forms: the paedomorphs occupied all the micro-habitats (shore, bottom, water column and surface) while the metamorphs were only found along the shore and at the water surface. In such a deep lake paedomorphosis may have persisted because of a different use of both feeding resources and micro-habitat [less ▲]

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See detailSM98-146/413 Effective Modal Parameters to Evaluate Structural Stresses
Rochus, Pierre ULg; Defise, Jean-Marc ULg; Plesseria, Jean-Yves ULg et al

in Spacecraft Structures, Materials and Mechanical Testing (1999)

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See detailThe pregnancy-associated glycoproteins in sheep: new investigations by using the Ouchterlony technique.
El Amiri, B.; Garbayo, J. M.; Mecif, K. et al

in Proceedings of the 15th Scientific Meeting of the European Embryo Transfer Association (1999)

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See detailStudy and Characterization of Inclusions in Steels obtained from ESR and Conventionally Electrical Ingot Processes
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg

in Proceedings of the Annual Meeting of the SBM (société belge de microscopie). (1999)

The aim of this research is to establish in a quantitative and statistically justifiable way the relationship between on the one hand, the cleanliness of the steel, the amount of carbides and the ... [more ▼]

The aim of this research is to establish in a quantitative and statistically justifiable way the relationship between on the one hand, the cleanliness of the steel, the amount of carbides and the microstructure of the materials, and then on the other hand their mechanical properties in service. [less ▲]

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See detailLa responsabilité pénale de l'entreprise et le droit social
Kefer, Fabienne ULg

in Les sociétés bientôt punissables. Quel impact sur la vie des entreprises? (1999)

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See detailCharacterization of menin from leucocytes of normal and men-1 affected individuals
Poncin, Jacques ULg; Closset, Jean ULg; Legros, Jean-Jacques ULg et al

in 81st Annual Meeting of the Endocrine society - Abstract book (1999)

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See detailLandscape assessment by graphical evenness analysis. Landscape Ecology – The science and the action
Van Hecke, P; Bogaert, Jan ULg; Salvador-Van Eysenrode, D

in Proceedings of the 5th World Congress of the International Association for Landscape Ecology (IALE). (1999)

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See detail"Quasi-Static Response" (Discussion on the Report of Committee II.1); Reply to E. Rizzuto)
Rigo, Philippe ULg

in 13th Int. Ship and Offshore Structures Congress (1999)

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See detailLes garanties offertes en terme de bien-être animal
Nicks, Baudouin ULg

in Compte-rendu de la journée d'études de la BAMST (1999)

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See detailA conceptual framework of educational robotics
Denis, Brigitte ULg; Hubert, Sylviane

in Proceedings of the 9th International conference on Artificial Intelligence in Education, AI-ED 99 (1999)

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See detailDiminution de volume d'un macro-adénome à ACTH (silencieux) sous Cabergoline
Khalife, A.; Ronci, N.; Stevenaert, Achille ULg et al

in XVIIème Congrès de la Société Française d'Endocrinologie - Abstract book (1999)

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See detailEffect of austenite destabilisation heat treatment on graphite precipitation in chromium iron
Lecomte-Beckers, Jacqueline ULg; Terziev, Luben; Breyer, Jean-Pierre

in Proceedings of the International Conference on Solid-SoUd Phase Transformations ‘99 (JIMIC3) (1999)

During solidification of chromium iron, carbides such as M7C3 are precipitating. It is possible to obtain crystallized graphite in the asaCast state by modifying the composition of the alloy[lJ.The aim of ... [more ▼]

During solidification of chromium iron, carbides such as M7C3 are precipitating. It is possible to obtain crystallized graphite in the asaCast state by modifying the composition of the alloy[lJ.The aim of the study is to understanding the mechanism of precipitation of graphite not only during solidification but also during heat treatment. Dilatometric, microcalorimetric, resistometric and microstructural examination methods were used for the investigations. We have shown that graphite precipitation occurs by decomposition ofM7C3 chromium carbides during austenite destabilisation heat treatment. The shape and the amount of graphite depend on the treatment temperature and time. [less ▲]

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See detailSurface methods for cleaner steels : evaluation of inclusions and grain boundary segregations by electrochemical impedance spectroscopy
Perez, F. J.; Duday, D.; Hierro, M. P. et al

in Proceedings of The International COST-517 : Workshop on Cleaner Metals for Industrial Exploitation (1999)

The structure, defects concentration and the Corrosion resistance of oxide scales formed at 650°C on hot rolling roils composed of HSS steels without or with a 4% Co addition were examined by ... [more ▼]

The structure, defects concentration and the Corrosion resistance of oxide scales formed at 650°C on hot rolling roils composed of HSS steels without or with a 4% Co addition were examined by electrochemical impedance spectroscopy. Scales were obtained aller I , 3 and 6 days of oxidation in air. For ail the steels, Fe203 and Cr203 were mainly formed at the surface. The difference of corrosion behavior is due to the thickness, the microstructure ami the porosity of the scale, which are influenced by the time of oxidation and the Co addition. Corrosion examinations were carried out in a O.5M NaCI solution at ambient temperature. The Co addition has a effect on increasing the corrosion resistance for the non-oxidized and oxidized samples but this effect is limited in tinie. The corrosion increased with die lime of immersion except for the HSS without Co oxidized 3 days. After 6 days of oxidation, the resistarice to COITOSIOfl iS two orders of magnitude higher that means a critical scale thickness was reached. [less ▲]

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See detailNarrow-band photometry of the eclipsing WN7+O binary WR 22
Royer, P.; Rauw, Grégor ULg; Manfroid, Jean ULg et al

in Wolf-Rayet Phenomena in Massive Stars and Starburst Galaxies (1999)

In the present paper, we discuss photometric observations of the February 1996 eclipse of the very massive WR+O binary WR 22. Our data were obtained with a set of narrow-band filters, specially designed ... [more ▼]

In the present paper, we discuss photometric observations of the February 1996 eclipse of the very massive WR+O binary WR 22. Our data were obtained with a set of narrow-band filters, specially designed for the study of WR stars. [less ▲]

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See detailMorphological particularities of the head in four Carapidae (Ophidiiformes)
Parmentier, Eric ULg; Chardon, Michel ULg; Poulicek, Mathieu ULg et al

in Séret, Bernard; Sire, Jean-Yves (Eds.) 5th Indo-Pacific Fish Conference, Noumea - New Caledonia, 3-8 November 1997: Proceedings (1999)

A study of the skull and the musculature of the oral and pharyngeal region of four adult Carapidae species (Encheliophis boraborensis, Encheliophis homei, Encheliophis gracilis and Carapus acus) has ... [more ▼]

A study of the skull and the musculature of the oral and pharyngeal region of four adult Carapidae species (Encheliophis boraborensis, Encheliophis homei, Encheliophis gracilis and Carapus acus) has undertaken to compare it with the diet related characters. The cephalic organization of E. boraborensis and E. gracilis seems related to diet (mainly fishes and shrimps for the first one and holothurian tissues for the other) : these fishes are respectively commensal and parasitic. Although the feeding characters of E. homei and C. acus are closely similar to those of E. boraborensis, there are sparse observations of holothurian tissues in their stomach contents. It is suggested that these fishes are commensal when they are adults and have parasitic tendency when they are juvenile. [less ▲]

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See detailGrowth hormone and parturition adversely influence immunoreactive plasma insulin-like growth factor binding protein-2 in cattle.
Vleurick, Lieve; Vandehaar, M.; Bertozzi, Carlo et al

in Growth Hormone & IGF Research (1999)

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See detail-agonist or corticoids treatment differently alter insulin-like growth factor (IGF)-I and IGF-binding protein-2 plasma levels in finishing bulls.
Renaville, Robert ULg; Bertozzi, Carlo; Parmentier, Isabelle et al

in Growth Hormone & IGF Research (1999)

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See detailModelaçao Numérica da Encurvadura Lateral de Vigas I Metalica Sujeitas à Acçao do Fogo
Vila Real, Paulo; Piloto, Paulo; Franssen, Jean-Marc ULg

in Proc. II National Conference on Steel and Composite Construction (1999)

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See detailOn the motion of trapped particles in the vicinity of corotation centers
Beaugé, C.; Lemaitre, Anne; Jancart, Sylvie ULg

in Ferraz-Mello, S. (Ed.) Impact of Modern Dynamics in Astronomy (1999)

In this presentation we revisit the analytical determination of the corotation solutions of the restricted planar three-body problem under the effects of a Stokes drag. Previous calculations by different ... [more ▼]

In this presentation we revisit the analytical determination of the corotation solutions of the restricted planar three-body problem under the effects of a Stokes drag. Previous calculations by different authors, and using different external dissipative forces, have always shown significant quantitative errors of the models with respect to the numerical values. Up to date no concrete explanation has been obtained for this discrepancy. We show that the origin of these errors lies not only in the modelization of the gravitational forces (i.e. disturbing function) but in the averaging process of the variational equations. A second-order averaging is developed based on a Lie transform method (Kamel, 1969). With it we can calculate new equilibrium solutions with a greatly improved accuracy. In a second part, this same perturbation method is applied to study the periodic orbits (i.e. limit cycles) which describe the motion of the particles around the averaged corotational solutions. We show how analytical approximations of these cycles can be obtained through the inverse transformation of the averaging process itself. In all cases, we present comparisons with numerical simulations of the exact equations. [less ▲]

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See detailPreliminary characterization of the promoter and CIS-regulatory elements of the MEN1 gene
Vanbellinghen, Jean-François ULg; Beckers, Albert ULg; Poncin, J.

in The 6th International Pituitary Congress - Abstract book (1999)

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See detailCabergoline in the treatment of Hyoerprolactinemia : A study in 455 patients
Verhelst, J.; Abs, R.; Maiter, D. et al

in 9th Meeting and workshop of the European Neuroendocrine Association - Abstract book (1999)

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See detailA DMS platform for monitoring and analysing large distribution networks
Rousseaux, Patricia ULg; Quoilin, Isabelle; Van Cutsem, Thierry ULg et al

in Proceedings of the 15th International Conference on Electricity Distribution (1999)

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See detailSpawning tactics and reproductive success in two european cyprinids, the barbel (Barbus meridionalis) and the bream (Abramis brama) : an overview.
Poncin, Pascal ULg; Binda, O.; Termol, C. et al

in Norberg, B.; Kjesbu, O. S.; Taranger, G. L. (Eds.) et al Proceedings of the 6th International Symposium on Reproductive Physiology of Fish (1999)

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See detailImportance of Heat Treating Procedure in the Study and the Characterization of Impurities in high alloyed Steels
Lecomte-Beckers, Jacqueline ULg; Tchuindjang

in Proceedings of The International COST-517 : Workshop on Cleaner Metals for Industrial Exploitation (1999)

This paper deals with the methodology used in a COST 517 research concerning study of inclusions in high alloyed steel for mechanical purpose. In order to establish in a quantitative and statistically ... [more ▼]

This paper deals with the methodology used in a COST 517 research concerning study of inclusions in high alloyed steel for mechanical purpose. In order to establish in a quantitative and statistically justifiable way the relationship between impurities, inclusions and mechanical properties of high alloyed steels, we have to insure that the microstructure on the whole batch of specimens of the same origin is similar. This required appropriated heat treatments before achieving mechanical tests. Otherwise, metallurgical properties of the samples could vary, and the relationship between inclusions and mechanical properties misunderstood. Regardless of the melting or die atmosphere during the melting, inclusions are present in varying amounts in every commercial steel products. Since inclusions significantly influence properties and behavior of materials and at the same time give indications on the quality of the steel, it is quite interesting to precise their nature and their origin. This requires methods of identifying the inclusions and a knowledge of the history during steel making. [less ▲]

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See detailCaractéristiques principales des alliages d'aluminium
Lecomte-Beckers, Jacqueline ULg

in Chaire Aluminium organisée par l'Aluminium Center Belgium et le FNRS (1999)

Les propriétés de l'aluminium qui rendent ce métal et ses alliages si attractifs pour de nombreuses applications sont l'apparence, la légèreté, la facilité de fabrication, les propriétés physiques et ... [more ▼]

Les propriétés de l'aluminium qui rendent ce métal et ses alliages si attractifs pour de nombreuses applications sont l'apparence, la légèreté, la facilité de fabrication, les propriétés physiques et mécaniques et bien sûr la résistance à la corrosion. Les applications majeures de l'aluminium peuvent être classées en ordre décroissant de taille de marché et concernent la construction, l'emballage, le transport, les applications électriques, les biens de consommation, les machines et équipements. [less ▲]

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See detailGravitational Lensing by Damped LY alpha Absorbers
Smette, A.; Claeskens, Jean-François ULg; Surdej, Jean ULg

in Carilli, C. L.; Radford, S. J. E.; Menten, K. M. (Eds.) et al Highly Redshifted Radio Lines, ASP Conf. Series Vol. 156 (1999)

Spiral galaxies are thought to be the main responsible for the damped Ly-alpha (DLA) systems seen in QSO spectra. They can also act as gravitational lenses, affecting quantities derived in DLA surveys ... [more ▼]

Spiral galaxies are thought to be the main responsible for the damped Ly-alpha (DLA) systems seen in QSO spectra. They can also act as gravitational lenses, affecting quantities derived in DLA surveys. Assuming that z > 0 spiral galaxies are similar to local ones, we find that, at z 0.5, the number density of DLA systems may be over-estimated by up to 90% and the HI cosmological density (Omega[SUB]HI[/SUB]) by up to 170% in a survey using bright b[SUB]q[/SUB] = 16, z[SUB]q[/SUB] ga 2 QSOs and in the absence of important extinction by dust. Applying our model to existing surveys, we find that Omega[SUB]HI[/SUB] is significantly over-estimated only in the z < 1.7 ones (by 34%). Furthermore, statistical tests indicate that these surveys are indeed affected by gravitational lensing at a 2.3% confidence level. If luminosity functions for flat-spectrum radio-sources and optically selected QSOs are similar in shape and slopes, similar Gling effects should affect surveys for 21cm absorbers using bright, high-z flat-spectrum radio-sources. [less ▲]

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See detailRelationships between spirometric performances and occurrence and severity of respiratory disease in Belgian Blue calves
Bureau, Fabrice ULg; Fievez, Laurence ULg; Detilleux, J. et al

in Proceedings: 17th Symposium of the Comparative Respiratory Society (1999)

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See detailStrength of joints subjected to combined action of bending moments and axial forces
Jaspart, Jean-Pierre ULg; Braham, M.; Cerfontaine, F.

in Proceedings of the Conference Eurosteel 1999 (1999)

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See detailProgress in the modelization of light reflection for lighting calculations
Embrechts, Jean-Jacques ULg

in Proceedings of the 24th Session of the C.I.E. , CIE Publication n°133-Part 1 (1999)

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See detailExploration isocinétique de la pathologie fémoro patellaire
Croisier, Jean-Louis ULg; Foidart-Dessalle, Marguerite ULg; Reginster, S. et al

in Actes de la 2ème Journée lilloise de Pathologie du Genou (1998, December 18)

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See detailPathologie fémoro patellaire et vaste médial
Croisier, Jean-Louis ULg; Forthomme, Bénédicte ULg; Crielaard, Jean-Michel ULg

in Actes de la 2ème Journée lilloise de Pathologie du Genou (1998, December 18)

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See detailWFPC2 PSF Subtractions
Baggett, S.; Remy, M.; Surdej, Jean ULg et al

in Bulletin of the American Astronomical Society (1998, December 01)

Subtraction of scaled PSFs from direct CCD images of quasars (or stars) offers not only the possibility of detecting the presence of host or foreground galaxies (or companions like brown dwarfs or planets ... [more ▼]

Subtraction of scaled PSFs from direct CCD images of quasars (or stars) offers not only the possibility of detecting the presence of host or foreground galaxies (or companions like brown dwarfs or planets) but also provides a means of deriving accurate photometry of the primary objects. A series of PSF subtraction tests have been performed, using observed PSFs from the WFPC2 PSF Library as well as TinyTim PSFs; preliminary results indicate that appropriate synthetic TinyTim PSFs perform as well as observed PSFs. Specifically, using an optimally selected observed PSF, near the target on the chip ( < 10arcsec ), close in focus (within 1-2 microns), similar in spectral type, and with good S/N, yielded single photometric values with an RMS of ~ 0.01-0.02 mag. Using a carefully constructed synthetic PSF, close in focus and jitter to the target image, and as close as possible to the center of the target, resulted in photometric results with an RMS similar to that achieved with the observed PSF (0.01-0.02 mag). [less ▲]

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See detailDeep imaging of AXJ2019+112: The luminosity of a ``Dark Cluster''
Benitez, N.; Broadhurst, T.; Rosati, P. et al

in Paul, J.; Montmerle, T.; Aubourg, E. (Eds.) 19th Texas Symposium on Relativistic Astrophysics and Cosmology (1998, December 01)

We detect a distant cluster of galaxies at z ~1 centered on the QSO lens and luminous X-ray source AXJ2019+112 (Hattori et al 1997). The mass-to-light ratio within an aperture of 0.4 h ^{-1}Mpc determined ... [more ▼]

We detect a distant cluster of galaxies at z ~1 centered on the QSO lens and luminous X-ray source AXJ2019+112 (Hattori et al 1997). The mass-to-light ratio within an aperture of 0.4 h ^{-1}Mpc determined using the X-ray temperature is M_x / L_V = 190^{+95}_{-66}h(M/L_V)[SUB]sun[/SUB]. The strong lens model yields a compatible value, M/L_V = 315^{+80}_{-80}h(M/L_V)[SUB]sun[/SUB], whereas an independent weak lensing analysis sets an upper limit of M/L_V < 440 h(M/L_V)[SUB]sun[/SUB]. This confirms that AXJ2019+112 has a M/L ratio similar to that of z < 1 massive clusters. [less ▲]

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See detailCoupling thermal simulation and airflow calculation for a better evaluation of natural ventilation strategies
Andre, Philippe ULg; Kummert, M.; Nicolas, Jacques ULg

in Proceedings SSB'98 (1998, December)

A lot of building simulation tools are available today on the market. Most of them rely on very simplified hypotheses concerning the appraisal of airflows: very often, a constant (userdefined) airflow is ... [more ▼]

A lot of building simulation tools are available today on the market. Most of them rely on very simplified hypotheses concerning the appraisal of airflows: very often, a constant (userdefined) airflow is supposed, either to quantify the infiltration rate of a building or to estimate the coupling coefficients between zones. On the other hand, some recent tools become available to calculate air flow couplings between the different zones of a building or between a building and its environment. Those tools rely on simplified hypotheses concerning the temperatures distribution in a building. From that observation, it is obvious that a strong complementarity exists between both categories of tools. Several methods are available to perform this coupling and they are briefly described in the paper. Then, one of these methods is considered in details and successly engineered for the global simulation of two Case Studies of the IEA Annex 30 project: an office building in Germany and an appartment building in Poland. Both applications show the relevancy of the coupling process and the impressive impact on some simulation results. A parametric analysis of some key variables is also performed. As a conclusion, the paper identifies the limitations of the coupling method which is used in this case and proposes some improvements based upon an increase of the automization and integration process. [less ▲]

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See detailIEA Annex 30 : bringing simulation to application. Conclusions of subtask 1 : model qualification
Andre, Philippe ULg; Bourdouxhe, J.-P.; Lebrun, Jean ULg

in Proceedings of SSB'98 (1998, December)

From 1995 to 1998, IEA Annex 30 "Bringing Simulation to Application" has been adressing the problem of improving the conditions aiming at a more effective use of building and HVAC simulation among ... [more ▼]

From 1995 to 1998, IEA Annex 30 "Bringing Simulation to Application" has been adressing the problem of improving the conditions aiming at a more effective use of building and HVAC simulation among consulting engineers and building practitioners. Therefore, the project gathered both academic research teams and several consulting offices representatives in order to demonstrate, on real Case Studies, what should be done to achieve this goal. The first Subtask of the IEA Annex 30 was dealing with the most fundamental step appearing in the process of simulation use: qualification of the models implemented in the available simulation tools. The objective of the Subtask was to establish a framework allowing any simulation models developper to provide the necessary information making any simulation model user more confident when using such tools. To achieve this objective, Subtask 1 was divided in two parts: - a first part dealing with a survey of the available models and data resources useful for building and HVAC simulation; - a second part dealing with the development and the application on several examples of "model qualification procedures", which provides the required framework. The survey action was mainly focussing on the following items: models, meteorological data, internal gains, HVAC and material databases. The model qualification procedure was first defined as a sequence of operations involving several steps: model documentation, parameters identification, examples of use and sample results, validation (or verification of the models), integration in a data exchange process. This procedure was applied to several building and HVAC models: building thermal zones, cooling coil, chiller and cooling tower. [less ▲]

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See detailConditions pratiques et thérapeutiques de la césarienne dans l'espèce bovine : résultats d'une enquête franco-belge.
Hanzen, Christian ULg; Houtain, Jean Yves

in Navetat, Henri; Schelcher, François (Eds.) Le nouveau peripartum (1998, November 28)

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See detailExploration isocinétique du genou : importance pour la rééducation fonctionnelle
Croisier, Jean-Louis ULg

in Actes du Symposium National de Réadaptation (1998, November 28)

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See detailDesign and verification of the Far Ultraviolet Spectrographic Imager (FUV-SI) for the IMAGE mission
Renotte, Etienne ULg; Habraken, Serge ULg; Rochus, Pierre ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (1998, November 01)

The IMAGE FUV-SI is simultaneously imaging auroras at 121.8 nm and 135.8 nm. The spectrograph design challenge is the efficient rejection of the intense Lyman-alpha emission at 121.6 nm while passing its ... [more ▼]

The IMAGE FUV-SI is simultaneously imaging auroras at 121.8 nm and 135.8 nm. The spectrograph design challenge is the efficient rejection of the intense Lyman-alpha emission at 121.6 nm while passing its Doppler-shifted component at 121.8 nm. The FUV-SI opto-mechanical design, analysis integration, and verification of performances against environment are discussed in this paper. In absence of STM environmental constraints at subsystem levels are derived analytically from F.E.M. and used for pre-qualifying optical subsystems. [less ▲]

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See detailVers une formation initiale en didactique des langues germaniques axée sur l'articulation de la théorie et de la pratique didactiques
Simons, Germain ULg

in Hiligsmann, Philippe (Ed.) ANBF-Nieuwsbrief (1998, November)

Selon G. Simons, le simple organigramme d'un cours de didactique spéciale véhicule une certaine représentation de ce que sont ou devraient être l'enseignement et l'apprentissage. Cette conception est ... [more ▼]

Selon G. Simons, le simple organigramme d'un cours de didactique spéciale véhicule une certaine représentation de ce que sont ou devraient être l'enseignement et l'apprentissage. Cette conception est progressivement intériorisée par les étudiants, dans le cas présent, de futurs enseignants en langues germaniques, et constitue un curriculum latent qui risque d'influencer (in)directement leur manière d'enseigner. Dans cette communication, G. Simons décrit et commente brièvement un ensemble de micro-réformes introduites dans la macro-structure méthodologique de la formation initiale en Didactique des Langues germaniques à l'Université de Liège de 1990 à 1998. Toutes ces micro-réformes poursuivent un seul et même objectif final : favoriser l'articulation de la théorie et de la pratique didactiques ou former des praticiens réfléchis. [less ▲]

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See detailGestion de ressources humaines volatiles : la GRH à l’heure des Techniciens de l’Information
Schoenaers, Frédéric ULg; Zune, Marc

in collectif (Ed.) Actes du Congrès de l'AGRH (1998, November)

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See detailOptimization of Ship Structure – Minimum Cost
Rigo, Philippe ULg

in Second International Shipbuilding Conference, ISC’98, Krylov Shipbuilding Research Inst. (1998, November)

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See detailCapillary and Gravity-driven Instabilities in Finite Circular Containers
Dauby, Pierre ULg; Narayanan, Ranga; Johnson, D. et al

in Bulletin of the American Physical Society, Vol. 43, n°9 (1998, November)

When a horizontal fluid layer is heated from below, convection sets in provided the vertical temperature gradient exceeds a critical value. The motion is due to a combined effect of gravity and ... [more ▼]

When a horizontal fluid layer is heated from below, convection sets in provided the vertical temperature gradient exceeds a critical value. The motion is due to a combined effect of gravity and capillarity when the upper surface of the fluid is free. Convection usually takes the form of a regular pattern of convective cells, which are often hexagonal or roll-like in horizontally infinite layers. In confined geometries, the appearance of the instability phenomenon is greatly influenced by the presence of lateral walls which inhibit convection due to friction and which also determine the shape of the convective cells. In this work we present a theoretical and experimental analysis of the thermo-convective instability of a fluid layer contained in a circular container. The motion and the temperature perturbations in the air layer above the fluid are also taken into account. The convective threshold is determined as a function of the aspect ratio of the vessel and the convective stationary and oscillatory structures appearing in the non linear regime are also studied. Experimental results are presented and compared with the theoretical approach. [less ▲]

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See detailInterférométrie holographique avec cristaux photoréfractifs en régime impulsionnel. Développements et résultats préliminaires
Georges, Marc ULg; Pauliat, Gilles; Lemaire, Philippe et al

in Actes du 10e séminaire SFO/HOLO3 : Nouveaux moyens optiques pour l'industrie (1998, November)

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See detailFormer pour promouvoir un changement des comportements ? Enjeux et méthodes de l'éducation pour la santé
Mairiaux, Philippe ULg; Vandoorne, Chantal ULg

in Formation - Information des salariés (1998, October)

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See detailL'immersion linguistique en milieu scolaire : De l'utilité de l'apprentissage précoce des langues étrangères
Comblain, Annick ULg

in Comblain, Annick (Ed.) Proceedings des Entretiens de Bichat partim Ortophonie (1998, September 11)

Il est superflu, aujourd’hui, d’insister sur la nécessité tant individuelle que culturelle mais surtout économique de connaître une ou plusieurs langues étrangères. Face à cet état de fait, il est ... [more ▼]

Il est superflu, aujourd’hui, d’insister sur la nécessité tant individuelle que culturelle mais surtout économique de connaître une ou plusieurs langues étrangères. Face à cet état de fait, il est souhaitable de fournir aux jeunes enfants les meilleures opportunités d’apprendre une seconde langue de manière intensive dans leur cursus scolaire. Les préoccupations scientifiques sur les divers aspects du bilinguisme ne sont pas neuves. Depuis plusieurs décennies, les psychologues, les éducateurs et les sociologues s’interrogent sur les effets individuels et sociaux de la pratique de plusieurs langues. Ce n’est cependant que récemment qu’une réflexion sérieuse sur les méthodes et les contextes de cet apprentissage linguistique est née. La raison en est, sans nul doute, le sentiment généralement partagé de l’inefficacité de l’apprentissage traditionnel des langues. Sur le modèle de ce qui se fait au Canada depuis plus d'un quart de siècle, la Belgique est un des rares pays a avoir, du moins à titre expérimental, introduit l’immersion dans son système scolaire et ce depuis 10 ans maintenant. Les avantages de l’enseignement immersif sont évidents : précocité et intensité d’exposition à la langue cible, caractère motivant et fonctionnel de la pratique linguistique. Les inconvénients, avec des enfants normaux sont nuls ainsi que l’attestent un grand nombre d'études canadiennes. La pratique immersive n’est un embarras ni pour le développement des capacités et des connaissances en langue maternelle, ni pour la maîtrise des matières inscrites au programme scolaire . Au terme de la scolarité secondaire, les enfants immergés présentent d’impressionnantes capacités discursives en langue seconde tant d’un point de vue réceptif que productif. Ces capacités discursives, bien qu’encore inférieures à celle de locuteurs natifs du même âge, sont très nettement supérieures à celles des enfants ayant suivi un enseignement traditionnel. Les résultats obtenus par la méthode immersive semblent donc de nature à améliorer de manière considérable les capacités linguistiques des enfants. Un certain nombre de recherches sont cependant encore nécessaires afin de préciser les modalités optimales de l’apprentissage des langues étrangères dans les contextes éducatifs. [less ▲]

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See detailLe froment d'hiver
Couvreur, Luc; Bodson, Bernard ULg; Herman, Jean-Luc et al

in Fumure et protection phytosanitaire des céréales: Informations avant les semis des céréales (1998, September 10)

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See detailEscourgeon et Orge d'hiver fourragère
Bodson, Bernard ULg; Herman, Jean-Luc; Monfort, Bruno et al

in Fumure et protection phytosanitaire des céréales: Informations avant les semis des céréales (1998, September 10)

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See detailSpectrophotometric Monitoring of Comet C/1995 O1 (Hale-Bopp): Pre- and Post-Perihelion
Rauer, H.; Helbert, J.; Arpigny, Claude ULg et al

in Bulletin of the American Astronomical Society (1998, September 01)

Spectrophotometric observations of comet C/1995 O1 (Hale-Bopp) were performed at the European Southern Observatory (ESO), Chile. From April to September 1996 its gaseous activity was monitored over a ... [more ▼]

Spectrophotometric observations of comet C/1995 O1 (Hale-Bopp) were performed at the European Southern Observatory (ESO), Chile. From April to September 1996 its gaseous activity was monitored over a heliocentric distance range from 4.6 AU to 2.9 AU. The monitoring is continued on Hale-Bopp's outbound path since September 1997 and covers up to now 3 AU to 5 AU heliocentric distance. Medium resolution spectra in the optical wavelength range from about 350 nm to 700 nm were taken at the 1.54m Danish and the 1.52m ESO telescope. Emission bands of the CN, C_3, C_2 and NH_2 radicals can be followed over the comet's orbit. We will present a first analysis of the post-perihelion activity evolution and compare to the pre-perihelion path. Currently, at 4.7 AU on the outbound path, we still see emission of CN, C_3, C_2 and NH_2. The production rate of CN showed a sudden increase around this heliocentric distance pre-perihelion (Rauer et al., Science 275, 1909). The post-perihelion activity evolution of CN and the other observed radicals in this distance range will be evaluated. [less ▲]

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See detailObservation of short and long timescale variability of the jovian UV aurora
Grodent, Denis ULg; Gérard, Jean-Claude ULg; Dols, V. et al

in Bulletin of the American Astronomical Society (1998, September 01)

Three sets of Hubble Space Telescope far-ultraviolet images of Jupiter's North pole aurora have been obtained with the Wide Field and Planetary Camera 2 in June 1996, May 1997 and August 1997. The ... [more ▼]

Three sets of Hubble Space Telescope far-ultraviolet images of Jupiter's North pole aurora have been obtained with the Wide Field and Planetary Camera 2 in June 1996, May 1997 and August 1997. The exposure time was limited to 160 seconds in order to reveal short timescale auroral features that are normally averaged during longer exposures and blurred by the rapid jovian rotation. The 3 sets of images show the aurora in a comparable (quiet) activity level, exhibiting long term persistent features such as : (i) a stable thin morning arc, (ii) a morning-afternoon emission dichotomy, (iii) a minimum of low latitude emission around CML=175 deg, (iv) bright localized afternoon structures. The equatorward boundary of the arc closely follows but is not coincident with the footprint of the 20 RJ magnetic field line given by the VIP4 model. These stable structures contrast with rapidly changing features like small size spots blasting in one single image, bright regions connecting trans-auroral structures, and the inner diffuse emission. The question of temporal variability and spatial extent of the auroral features is of major importance in understanding the origin and acceleration mechanisms of the auroral particles exciting the jovian UV aurora. In particular, short timescale processes can be related to field aligned currents generating acceleration structures and discrete aurora. [less ▲]

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See detailFUV spectroscopy of the H_2 emission in the Jovian aurora: model update and results
Gérard, Jean-Claude ULg; Dols, V.; Colignon, David ULg et al

in Bulletin of the American Astronomical Society (1998, September 01)

The Jovian aurora exhibits bright emissions mainly due the bright Lyman-alpha line and to radiation from excited singlet states to the ground electronic state extending from 800 to 1600 Angstroms. Above ... [more ▼]

The Jovian aurora exhibits bright emissions mainly due the bright Lyman-alpha line and to radiation from excited singlet states to the ground electronic state extending from 800 to 1600 Angstroms. Above 1200 Angstroms, the molecular spectrum is dominated by the Lyman (B-X) bands and continuum and the Werner (C-X) bands. These transitions have been observed with the Goddard High Resolution Spectrometer (GHRS) and the Space Telescope Imaging Spectrometer (STIS) at various spectral and spatial resolutions. To analyze these spectra, a model synthetic auroral spectrum has been constructed and applied to the analysis of the ro-vibrational temperature of H_2 and a search for non-H_2 emission features. It has been recently updated to include the latest singlet state excitation and cascading cross sections, self-absorption in optically thick lines and to account for the energy distribution of the secondary electrons which cause additional excitation. We illustrate these effects in a few study cases and apply the model to high resolution (0.5 Angstroms) GHRS spectra and low resolution STIS spectra of the entire H_2 spectrum at wavelengths longer than Lyman-alpha. We determine the methane column overlying the auroral emission peak and find that a better fit is obtained with additional absorption by acetylene. [less ▲]

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See detailHST-STIS Observations of Jupiter's Aurora
Clarke, J. T.; Ajello, J.; Ballester, G. E. et al

in Bulletin of the American Astronomical Society (1998, September 01)

HST observations of the UV emissions from Jupiter's aurora have been obtained with the new Space Telescope Imaging Spectrograph (STIS) since July 1997. UV images of the aurora are now possible with an ... [more ▼]

HST observations of the UV emissions from Jupiter's aurora have been obtained with the new Space Telescope Imaging Spectrograph (STIS) since July 1997. UV images of the aurora are now possible with an order of magnitude higher sensitivity than possible with earlier cameras, and improved angular resolution from shorter exposures. Images have been obtained at 4 epochs since Sept. 1997, and reveal several new features of the auroral emission pattern. These include i) faint auroral emissions extending roughly 60 deg. in the wake or plasma flow direction beyond Io's magnetic footprint, ii) systematic motions of the main auroral oval both toward the pole and toward the equator at different local times and longitudes, and iii) clear identification of an auroral emission feature with Ganymede's magnetic footprint, from the relative motion of the feature remaining underneath Ganymede in a time series of images. Preliminary interpretations of these features will be presented. Spectra have also been obtained of auroral emission features including the northern and southern main ovals, the diffuse emission poleward of the main oval, and the northern and southern Io footprints. These spectra will be presented with estimates of the overlying hydrocarbon columns, the energy of the exciting electrons, the rotational temperature of the emitting hydrogen, and the overlying column of atomic hydrogen. This work was supported by NASA under grants GO-6743.01-95A and GO-7308.01-96A to the University of Michigan. [less ▲]

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See detailJovian Auroral Lyalpha Self-Reversals: A Window on Jupiter's Auroral Electrojet?
Gladstone, G. R.; Waite, J H, Jr; Gérard, Jean-Claude ULg

in Bulletin of the American Astronomical Society (1998, September 01)

High-resolution GHRS profiles of Lyalpha lines emitted from Jupiter's auroral regions were presented by Prang{e} et al. (Astrophys. J., 484, L169--L173, 1997). Their data show asymmetric self-reversed ... [more ▼]

High-resolution GHRS profiles of Lyalpha lines emitted from Jupiter's auroral regions were presented by Prang{e} et al. (Astrophys. J., 484, L169--L173, 1997). Their data show asymmetric self-reversed line profiles, with the blue or red peak brighter depending on the target location in Jupiter's northern auroral region. The measured asymmetries are equivalent to Doppler velocities towards and away from the observer of several km/s. As suggested by Sommeria et al. (Icarus, 119, 2--24, 1995), electrojet velocities of ~ 10--20 km/s may be present at Jupiter. Here we investigate the possibility that the observed wavelength shifts of the auroral Lyalpha line are a result of multiple scattering by H atoms carried along in Jupiter's auroral electrojet. If this explanation is found to be viable, then HST/STIS mapping of the velocity shifts in the Lyalpha line may represent (as with ground-based high-resolution observations of jovian auroral H_3(+) emission lines) a means for determining the dynamics of Jupiter's upper atmosphere and ionosphere. [less ▲]

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See detailThe Jovian Aurora: Implications of Multiwavelength Auroral Spectra for Auroral Particle Identity and Auroral Microphysics
Waite, J. H.; Gladstone, G. R.; Bolton, S. J. et al

in Bulletin of the American Astronomical Society (1998, September 01)

Remote sensing of Jupiter's aurora from x-ray to radio wavelengths has revealed much about the nature of the jovian aurora and about the impact of ionosphere-magnetosphere coupling on Jupiter's upper ... [more ▼]

Remote sensing of Jupiter's aurora from x-ray to radio wavelengths has revealed much about the nature of the jovian aurora and about the impact of ionosphere-magnetosphere coupling on Jupiter's upper atmosphere. Both energetic heavy ions and electrons energized in the outer magnetosphere contribute to the auroral excitation, as indicated by the combination of x-ray and ultraviolet observations. Imaging with the HST in the ultraviolet and with the IRTF at infrared wavelengths reveals several distinct regions of interaction: 1) a dusk sector where turbulent auroral patterns extend well into the polar cap; 2) a morning sector generally characterized by a single spatially confined auroral arc originating in the outer magnetosphere of Jupiter; 3) diffuse emissions associated with the Io plasma torus; and 4) a distinct region associated with the Io Flux Tube footprint. Ultraviolet spectroscopy has provided important information about the thermal structure of the upper atmosphere and altitude distribution of the auroral particle energy deposition, while Lyman alpha line profiles offer clues to the nature of thermospheric dynamical effects. Galileo observations at visible wavelengths on the nightside have provided a new view of the jovian aurora with unprecedented spatial information. Infrared observations have added much to the understanding of thermal structure and morphology and may hold the key to understanding the role of Joule heating. Radio observations imply that energetic particle precipitation extends to low latitudes, a result that has been corroborated at x-ray wavelengths. Multispectral observations of jovian auroral emissions will be discussed within a theoretical/modeling framework that serves to provide some insight into magnetosphere-ionosphere coupling and its effect on the upper atmosphere. Particular emphasis will be placed on the use of auroral spectra to identify incident energetic particles and their energy spectra as a means of elucidating the microphysics of auroral processes. [less ▲]

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See detailFirst results on the evaluation of Haser scale lengths in comet Hale-Bopp (C/1995 O1) at R >= 3 AU
Helbert, J.; Rauer, H.; Arpigny, Claude ULg et al

in Bulletin of the American Astronomical Society (1998, September 01)

Due to its exceptional brightness, comet Hale-Bopp offered the possibility for unprecedented long-term monitoring. Medium resolution long-slit spectroscopic data and images were obtained using the Danish ... [more ▼]

Due to its exceptional brightness, comet Hale-Bopp offered the possibility for unprecedented long-term monitoring. Medium resolution long-slit spectroscopic data and images were obtained using the Danish Faint Object Spectrograph (DFOSC) at the 1.54m Danish telescope and the Boller and Chivens spectrograph at the 1.52m ESO telescope, La Silla, Chile. Pre-perihelion, comet Hale-Bopp was monitored from 4.6 AU to 2.9 AU and post-perihelion, the monitoring yields data from 3 AU up to a heliocentric distance of 5 AU. Production rates are often derived by using a simple Haser model to approximate the coma density distribution. This requires knowledge of the destruction scale lengths of the observed daughter species and its parents. As the brightness of most comets diminishes quickly with heliocentric distance, scale lengths have been determined only in comets around 1 AU. Due to the lack of data for large heliocentric distances, production rates in distant comets can only be derived by extrapolating these scale lengths. In this preliminary analysis of our data we evaluate the scale-lengths of CN, C_3 C_2, and NH_2 at heliocentric distances greater than 3 AU post-perihelion. The differences of production rates derived by using these directly determined and the extrapolated scale lengths are discussed. [less ▲]

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See detailActions possessoires et référé
Lecocq, Pascale ULg

in Formation permanente CUP. Les procédures en référé (1998, September)

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See detailShort-term weather forecasting for solar buildings optimal control : an application of neural networks
Kummert, M.; Andre, Philippe ULg; Guiot, J. et al

in Proceedings Eufit'98 (1998, September)

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See detailDobutamine stress testing in a canine model of progressive heart failure by rapid ventricular pacing: preliminary results
Mc Entee, Kathleen ULg; Clercx, Cécile ULg; Balligand, Marc ULg et al

in 8th ESVIM Meeting - Vienne - Autriche - septembre 1998 (1998, September)

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See detailEfficient Implicit Schemes for High-Speed Dynamics and Crash Simulation. Application to shock-absorber devices
Hogge, Michel ULg; GRAILLET, D.; Ponthot, Jean-Philippe ULg

in Proceedings of «ACOMEN’98», Advanced Computational Methods in Engineering: Invited Papers (1998, September)

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See detailIdentification of Nonlinear Aeroelastic Systems
Dimitriadis, Grigorios ULg; Cooper, J. E.

in Proceedings of the 1998 International Conference on Noise and Vibration Engineering (1998, September)

The successful identification of nonlinear systems could find uses in many aerospace applications including the validation of finite element models and tracking the stability of aircraft during flight ... [more ▼]

The successful identification of nonlinear systems could find uses in many aerospace applications including the validation of finite element models and tracking the stability of aircraft during flight flutter testing. The effectiveness of existing nonlinear system identification techniques is limited by various factors such as the complexity of the system under investigation and the type of nonlinearities present. In this work, a new approach is introduced that is able to identify multi degree-of-freedom systems featuring any type of nonlinear function, including discontinuous functions. The method is shown to yield accurate identifications of three different simulated aeroelastic systems containing a wide range of structural nonlinearities. [less ▲]

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See detailHeating optimal control applied to a passive solar commercial building
Kummert, M.; Andre, Philippe ULg; Nicolas, Jacques ULg

in Proceedings of EuroSun'98 (1998, September)

Passive solar features can lead to significant energy savings for building heating. However the intrinsic delay between solar gains and heating demand requires an intelligent control of auxiliary HVAC ... [more ▼]

Passive solar features can lead to significant energy savings for building heating. However the intrinsic delay between solar gains and heating demand requires an intelligent control of auxiliary HVAC system to minimise the energy consumption while preventing overheating periods. This paper describes the application of discrete-time optimal control to auxiliary heating of a passive solar commercial building. Simulation-based results using complex reference models are presented and discussed. The optimal controller is compared to classical "heatingcurve + Thermostatic valve" control. It is shown that optimal control can lead to substantial improvement of thermal comfort and energy consumption. [less ▲]

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See detailVolume of Structures : Application to Classical and Harmonic Structures
Samyn, Philippe; Latteur, Pierre ULg; Van Vooren, J.

(1998, September)

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See detailEffective Iterative Solvers for Highly Non-Linear & Large Deformation Pressure Dependent Problems
Boman, Romain ULg; Colantonio, Laurent; Ponthot, Jean-Philippe ULg

in Van Keer, R.; Verhegghe, B.; Hogge, M. (Eds.) et al Proceedings of ACOMEN'98, Advanced Computational Methods in Engineering, part 2: Contributed papers (1998, September)

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the ... [more ▼]

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the unconditionally stable backward Euler scheme to obtain the viscoplastic solution at each increment. To solve the large sparse non symmetric iteration matrix, we use the GMRES method. This fast iterative solver, in conjunction with an appropriate preconditioner, can save a lot a memory and CPU time when 3D problem are considered. A comparison between direct and iterative solvers will be discussed on two applications of cold compaction of powders. [less ▲]

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See detailReliable Approximation Schemes for Composite Structures Optimization"
Bruyneel, Michaël ULg; Vermaut, O.; Fleury, Claude ULg

in Van Keer, R.; Verhegghe, B.; Hogge, M. (Eds.) et al ACOMEN ’98 : an international conference on advanced computational methods in engineering : Ghent, 2-4 september 1998 (1998, September)

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See detailDisplacements of Structures
Samyn, Philippe; Latteur, Pierre ULg

(1998, September)

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See detailA study of vibrato : assessment by panel of judges compared to spectral analysis.
Morsomme, Dominique ULg

in XXIVth World Congress of the International Association of logopedics & Phoniatrics (IALP) (1998, August)

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