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See detailFrequency halving due to vortex pairing for the jet-slot oscillator
Billon, Alexis ULg; Glesser, Martin; Valeau, Vincent et al

Conference (2006, July)

At the outlet of the HVCA systems, whistling can occur, due to self-sustained oscillations. In this study, the ventilation outlet is modelled by a free plane subsonic jet impinging on a slotted plate ... [more ▼]

At the outlet of the HVCA systems, whistling can occur, due to self-sustained oscillations. In this study, the ventilation outlet is modelled by a free plane subsonic jet impinging on a slotted plate, leading to self-sustained tones production; this configuration is known as the jet-slot oscillator. The tone's frequency can be predicted through the vortex dynamics within the flow. For jet velocities higher than 16m/s, the tones couple with the flow-supply-duct’s resonances. These resonances control the vortex dynamics and reinforce the sound production, of about 20dB. Moreover, when the distance from the jet exit to the plate is increased and reaches 4.5 times the jet height, the fundamental frequency of the tones is suddenly halved due to some vortex pairing occurring at the end of the potential core of the jet. In this paper, the vortex pairing is observed with three different experimental techniques. Firstly, comparison between the radiated and the in-duct acoustic fields is conducted. Then the energy transfer from the fundamental to the sub-harmonics of the shear layer's velocity fluctuations is observed with anemometric measurements. Finally high speed flow visualizations are performed and allow to link the vortex impingement on the plate to the sound production. [less ▲]

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See detailPrediction of the reverberation time in rooms with non uniform absorptions using a diffusion model
Billon, Alexis ULg; Sakout, Anas

Conference (2006, July)

The acoustical comfort is now a comfort’s criterion which is taken into from the conception. The designers need therefore accurate tools to predict the acoustic quality of enclosures. Most of the ... [more ▼]

The acoustical comfort is now a comfort’s criterion which is taken into from the conception. The designers need therefore accurate tools to predict the acoustic quality of enclosures. Most of the acoustical comfort criteria are based on the reverberation time. When the room has proportionate dimensions and an uniform absorption, the statistical theory through Sabine or Eyring formulas allows good predictions of the reverberation time. Moreover, extensions of these relations by Millington or Cremer and Müller among others give quite satisfactory when the room is composed of materials with different sound absorption. In this study, the reverberation time in an enclosure is calculated via the numerical resolution of unstationary diffusion equation, model validated in coupled and industrial rooms. Firstly, an improvement of the boundary condition is proposed for highly absorbent surfaces. The diffusion model is then compared to several formulations of the statistical theory and a ray-tracing software for a cubic room with homogeneous walls’ absorption and with non homogeneous walls’ absorptions. Finally, an experimental validation is conducted for an enclosure with non uniformly distributed absorption. [less ▲]

Detailed reference viewed: 44 (4 ULg)
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See detailThe impact of translated tests on student' performances
Baye, Ariane ULg; Lafontaine, Dominique ULg

Conference (2006, July)

Detailed reference viewed: 2 (0 ULg)
See detailIo footprint: Position, Multiplicity, Variability
Bonfond, Bertrand ULg; Gérard, Jean-Claude ULg; Grodent, Denis ULg et al

Conference (2006, July)

Detailed reference viewed: 3 (1 ULg)
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See detailPerceptual and instrumental impact of new technology on surgical performance.
Blavier, Adelaïde ULg; Nyssen, Anne-Sophie ULg

Conference (2006, July)

Contradictory results were reported concerning the benefits of three-dimensional systems and new technology on surgical performance. Our study aimed to precisely evaluate perceptual and instrumental ... [more ▼]

Contradictory results were reported concerning the benefits of three-dimensional systems and new technology on surgical performance. Our study aimed to precisely evaluate perceptual and instrumental impact of new robotic technology on surgical performance and subjective impression. 60 medical students without any surgical experience were randomized into three groups (classical laparoscopy, robotic system in 3D or robotic system in 2D). After a familiarisation phase with the technique of their condition, they performed four tasks of increasing complexity and self-evaluated their performance answering a questionnaire. Finally, subjects performed the most difficult task with the technique they never used (technical switch). Our results showed significant better performance with classical laparoscopy than with robotic system in the familiarisation task. In the following tasks of increasing complexity, subjects significantly performed better, with more self-confidence, satisfaction and facility using robotic system in 3D than with classical laparoscopy. Robotic system in 2D provided significant worse results than 3D robotic system except for the last and most difficult task. Depth perception plays predominant role in easiest tasks whereas instrumental dimension is a determinant factor in performing finest tasks. Results are discussed in terms of consequences of new technology introduction for patient safety and surgeon’s training. [less ▲]

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See detailGastrointestinal prokinetics'efficiency and risk factors of development of postoperative ileus: clinical study.
Salciccia, Alexandra ULg; Péters, Fabrice; Gangl, Monika et al

Conference (2006, June 29)

Because of the lack of clinical data in the area, this clinical study was performed to evaluate gastrointestinal prokinetics’ efficiency. Material used includes 2 groups composed each one by 25 horses ... [more ▼]

Because of the lack of clinical data in the area, this clinical study was performed to evaluate gastrointestinal prokinetics’ efficiency. Material used includes 2 groups composed each one by 25 horses which underwent surgery for small intestinal lesions in the University of Liège between january 1997 and august 2005. The 2 groups were formed by a selection resulting in similar (or not significantly different) mean values for the age, gravity score, shock score, packed cell volume on admission in the clinic and length of resected intestine when an enterectomy was performed. Between the 2 groups, we searched also equal (or not significantly different) proportions of Belgian Warmblood, of females/males, of horses wich underwent an enterectomy, of horses which had a concomitant lesion of the large intestine and of horses wich needed 1 or more sedative α2 agonist drug during the postoperative period. One group was treated with gastrointestinal prokinetics (lidocaine, erythromycin, metoclopramide) systematically, whereas the other one not and the incidence and duration of postoperative ileus was evaluated. No significant difference in the incidence or the duration of postoperative ileus was found between the 2 groups. Because our results did not show any effect of prokinetics, a statistical analysis searched in these 50 horses the risk factors of postoperative ileus among the following parameters: breed, age, sex, gravity score, shock score, packed cell volume on admission in the clinic, protocol of induction of anaesthesia, duration of anaesthesia, performing an enterectomy and length of the resected intestine, concomitant lesion of the large intestine, and administration of sedative α2 agonists during the postoperative period. Only the Belgian warmblood breed and the administration of sedative α2 agonist drugs after the recovery from anaesthesia were significantly more important in the group where horses developed a postoperative ileus. Undoubdtedly, this study includes only 50 cases selected for the homogeneity of their parameters and not all the cases of small intestine surgery during the test period. In view of these results, it would be interesting performing this study again on a larger number of cases in a prospective manner. [less ▲]

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See detailLe problème du temps vécu dans L'Idiot de la famille
Cormann, Grégory ULg

Conference (2006, June 29)

Detailed reference viewed: 3 (0 ULg)
See detailSingulièrement universel. Le problème du temps chez le dernier Sartre
Cormann, Grégory ULg

Conference (2006, June 24)

Detailed reference viewed: 7 (0 ULg)
See detailAesthetic and Political Violence in the Work of Janet Frame
Delrez, Marc ULg

Conference (2006, June 23)

Detailed reference viewed: 2 (0 ULg)
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See detailQuels recours pour les soumissionnaires évincés?
Lewalle, Paul ULg; Donnay, Luc ULg

Conference (2006, June 21)

Detailed reference viewed: 59 (7 ULg)
See detailThe GBS: pro screening
MELIN, Pierrette ULg

Conference (2006, June 21)

Detailed reference viewed: 7 (0 ULg)
See detailLe devenir des grands prématurés
Senterre, Thibault ULg

Conference (2006, June 19)

Detailed reference viewed: 28 (3 ULg)
See detailDe l'anglais dans la littérature post-coloniale : enjeux interculturels
Tunca, Daria ULg

Conference (2006, June 17)

Detailed reference viewed: 8 (2 ULg)
Peer Reviewed
See detailControllability, Observability and Sensitivity Analysis in Biological Systems
Bullinger, Eric ULg

Conference (2006, June 16)

Detailed reference viewed: 9 (0 ULg)
See detailCésarienne urgente: quel délai, quelle organisation?
Brichant, Jean-François ULg

Conference (2006, June 10)

Detailed reference viewed: 6 (1 ULg)
Peer Reviewed
See detailExperimental study of a randomly agitated 2D granular pile
Lumay, Geoffroy ULg

Conference (2006, June 09)

Detailed reference viewed: 1 (1 ULg)
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See detailL’information sur les finances et les performances communales en Flandre
Husson, Jean-François ULg

Conference (2006, June 09)

Présentation de quelques instruments d'information budgétaire des pouvoirs locaux en Flandre

Detailed reference viewed: 12 (2 ULg)
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See detailKülpe et l'idée d'une critique de la raison empirique
Dewalque, Arnaud ULg

Conference (2006, June 09)

Oswald Külpe is known as one of the leaders of the so-called "Denkpsychologie" ("Psychology of thought"). I here present several aspects of his reflexions on the content-object distinction, which has been ... [more ▼]

Oswald Külpe is known as one of the leaders of the so-called "Denkpsychologie" ("Psychology of thought"). I here present several aspects of his reflexions on the content-object distinction, which has been emphasized in the Brentano-school and has exercised a decisive influence on the philosophy of psychology at the beginning of the 20th century. I nevertheless focus on the "ontological" status of the objet of thought, as it is analyzed by külpe in his famous work "Die Realisierung". [less ▲]

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See detailAfrican Studies in Wallonia
Tunca, Daria ULg

Conference (2006, June 02)

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See detailApplying the electronic nose in the environment : requirements for the instrument
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Delva, Julien

Conference (2006, June 01)

Applying the electronic nose to monitor environmental odours is not straightforward. The instrument must be adapted to the final objectives. It has to pass different steps : suitable sensor selection ... [more ▼]

Applying the electronic nose to monitor environmental odours is not straightforward. The instrument must be adapted to the final objectives. It has to pass different steps : suitable sensor selection, right choice of the target when supervised methods are used for data processing, choosing an odour-related dependant variable when using regressions, coping with the variability of environmental odour, taking the sensor drift into account, working only in concentrations above the limit of detection of the sensors, working with a mobile instrument in the field and coping with the ambient parameters. [less ▲]

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See detailObésité: aube hésitée, et quoi pour moi demain
Battisti, Oreste ULg

Conference (2006, June)

cette journée aborde le cocnept familial, l'aspect communautaire, l'épidémiologie, l'aspect nutritionnel, l'aspect somatique et l'aspect psychologique de l'obésité de l'enfant dans le cadre familial.

Detailed reference viewed: 38 (2 ULg)
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See detailIntegration of longevity into the Walloon genetic evaluation system
Vanderick, Sylvie ULg; Croquet, Coraline; Soyeurt, Hélène ULg et al

Conference (2006, June)

Detailed reference viewed: 29 (3 ULg)
See detailLa céramique de Terqa : le Bronze Ancien
Mas, Juliette ULg

Conference (2006, June)

Detailed reference viewed: 6 (0 ULg)
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See detailPrediction of the acoustics of coupled rooms with the acoustic-diffusion model
Valeau, Vincent; Billon, Alexis ULg; Hodgson, Murray et al

Conference (2006, June)

A general model is proposed to simulate the acoustics of coupled rooms. It is based on a diffusion equation, solved numerically to perform acoustic predictions. The presence of scattering objects –or the ... [more ▼]

A general model is proposed to simulate the acoustics of coupled rooms. It is based on a diffusion equation, solved numerically to perform acoustic predictions. The presence of scattering objects –or the “fittings”– is also taken into account. Distinct sub-volumes can be defined, representing either coupled volumes or zones with different fitting characteristics. Some sample results are presented, and compared with ray-tracing results and experimental data. Two situations are assessed: two coupled classrooms, and a room divided into two zones, one empty, one fitted. The diffusion-model predictions match the other data satisfactorily, both in terms of sound attenuation and sound decay. Diffusion-based results are obtained with the advantage of low computational time compared to ray-tracing results. [less ▲]

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See detailOn the implementation of a sensitivity analysis in a flexible multibody dynamics environment
Bruls, Olivier ULg; Duysinx, Pierre ULg; Eberhard, Peter

Conference (2006, June)

The dynamic performance of complex mechanisms, such as machine tools, manipulators, vehicles, engines or foldable structures, can be strongly affected by flexible phenomena. Therefore, the deformation ... [more ▼]

The dynamic performance of complex mechanisms, such as machine tools, manipulators, vehicles, engines or foldable structures, can be strongly affected by flexible phenomena. Therefore, the deformation effects should be considered as soon as possible in the design procedure, which motivates the development of automatic optimization techniques for flexible multibody systems. Advanced software tools are able to simulate the dynamic behaviour of such systems, but they typically involve extensive numerical treatments. Hence, gradient-based optimization methods are of special interest since they require a quite low number of simulations, but an important problem is to obtain the sensitivities of the objective function with respect to the design parameters. Since finite difference approaches lack robustness and computational efficiency, we propose to investigate analytical or semi-analytical sensitivity analysis. Several difficulties are inherent to the simulation of flexible mechanisms. A consistent geometric formulation is necessary to describe large amplitude motion as well as possible large deformations. Here, according to the nonlinear finite element formulation, the motion is parameterized using absolute nodal coordinates, and an updated Lagrangian point of view is adopted for the rotation parameters. The joints and the rigid-body conditions are represented by algebraic constraints between the nodal coordinates, leading to differential algebraic equations of motion (DAEs). Finally, the computation of the trajectories requires a reliable simulation algorithm for nonlinear DAEs. A strong advantage of the finite element method comes from its very systematic implementation, which facilitates the development of a semi-analytical sensitivity analysis. In this work, sensitivity analysis is performed for beam elements, rigid bodies and ideal joints. The global sensitivity is then obtained by numerical assembly of the elementary contributions and by integration in the time domain. Thus, a single but extended simulation is sufficient to compute the sensitivities with respect to all parameters. In order to illustrate the method and to demonstrate its efficiency, we consider the optimal design of a car engine, where the flexibility of the connecting rods between the crankshaft and the pistons is taken into account. The objective is to find a feasible mechanical design which minimizes the level of vibrations. [less ▲]

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See detailEarly life evolution, habitats and biosignatures. Astrobiology and Habitability workshop
Javaux, Emmanuelle ULg; Marshall, Craig

Conference (2006, June)

Detailed reference viewed: 7 (0 ULg)
Peer Reviewed
See detailCarbon nanotubes synthesis by CCVD process : kinetic study on a Fe-Co/Al2O3 catalyst
Pirard, Sophie ULg; Douven, Sigrid ULg; Bossuot, Christophe et al

Conference (2006, June)

Detailed reference viewed: 3 (0 ULg)
See detailCardiopulmonary resuscitation
Brichant, Jean-François ULg

Conference (2006, June)

Detailed reference viewed: 2 (0 ULg)
See detailNew developments in electrografting of thin polymer films
Jérôme, Christine ULg

Conference (2006, June)

Detailed reference viewed: 7 (1 ULg)
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See detailPotential estimation of fatty acid content in cow milk by mid-infrared spectrometry
Soyeurt, Hélène ULg; Dardenne, Pierre; Lognay, Georges ULg et al

Conference (2006, June)

Detailed reference viewed: 23 (3 ULg)
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See detailpH-responsive micelles in dilute and gel-like media
Willet, Nicolas ULg; Leyh, Bernard ULg; Gohy, Jean-François et al

Conference (2006, June)

Detailed reference viewed: 3 (0 ULg)
Peer Reviewed
See detailMobility and spawning migration of roach in three fragmented rivers in Belgium
Geeraerts, Caroline; Verbiest, Hilde; Buysse, David et al

Conference (2006, June)

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See detailRegulated discharge produces important changes of fish community in the grayling zone of a small salmonid stream.
Ovidio, Michaël ULg; Capra, Hervé; Orban, Patrice et al

Conference (2006, June)

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See detailA stability diagram computation method for milling adapted to automotive industry
Le Lan, Jean-Vincent; Marty, Audrey; Debongnie, Jean-François ULg

Conference (2006, June)

In this paper, a numerical method to compute stability diagrams is presentd. It is adapted to the particular case of automotive parts production where chatter arises due to the lack of stiffness of the ... [more ▼]

In this paper, a numerical method to compute stability diagrams is presentd. It is adapted to the particular case of automotive parts production where chatter arises due to the lack of stiffness of the workpiece. The main features of the model are the simultaneous immersion of many teeth, frequency domain computations and the use of the Finite Element Method to provide transfer function. [less ▲]

Detailed reference viewed: 93 (2 ULg)
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See detailRisktrainer, A training method for facilitating participatory risk management in companies
BALSAT, A.; LHERMITTE, Françoise; HAMBACH, R. et al

Conference (2006, June)

Detailed reference viewed: 3 (1 ULg)
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See detailTrophic diversity and potential role of detritivorous crustaceans in Posidonia oceanica litter
Sturaro, Nicolas ULg; Gobert, Sylvie ULg; Cox, Anne-Sophie et al

Conference (2006, June)

Detrivorous crustaceans are pivotal components of the trophic food webs and are found to be the main constituents of the macrofauna in Posidonia oceanica litter. The coexistence of many of these species ... [more ▼]

Detrivorous crustaceans are pivotal components of the trophic food webs and are found to be the main constituents of the macrofauna in Posidonia oceanica litter. The coexistence of many of these species in the same biotope raises the question of trophic diversity and of its role in litter degradation process. Diet composition of five common species of detrivorous crustaceans in P. oceanica litter (i.e. the gammarid amphipods Gammarella fusicola and Gammarus aequicauda and the isopods Idotea baltica, Idotea hectica and Zenobiana prismatica) were studied using a combination of gut content and stable isotopes analysis. Despite the common food supply (i.e. Posidonia dead leaf, Posidonia epiphytes or drift macroalgae), there were considerable interspecific differences in diet composition. Gut content observations indicate that P. oceanica leaf litter is an important part of the ingested food of all the species. Algae material (macroepiphytes and drift macroalgae) inhabiting the litter is mainly found in G. fusicola, I. hectica and I. baltica. I. baltica displays a high proportion of crustacean fragments. Isotope ratios showed that most of the species do not assimilate much of the ingested Posidonia. Application of a mixing model using isotopic values to estimate the contribution of the potential different food sources confirms this view. On one hand, the tissue of G. aequicauda could be constituted by more than 50 % of P. oceanica carbon. On the other hand, for the other species studied, P. oceanica represented a minor contribution (10 - 30 %), although it is a major component of the gut contents. This could imply that micro-organism (diatoms, bacteria and fungi) living on the Posidonia detritus is a major food source of detrivorous. Moreover, I. baltica, Z. prismatica and G. fusicola have a diversified diet composed mainly of algae. Crustaceans are an important food source for I. baltica. By contrast, I. hectica indicated a major contribution of algae material. Our results demonstrate the trophic diversity existing between the detrivorous crustaceans species in P. oceanica litter. This trophic diversity is probably one of the factors that allows these species to coexist in the same biotope. The results also underline the potential role of these species in the degradation of P. oceanica litter by fragmenting mechanically the Posidonia detritus and by assimilating directly Posidonia carbon and transferring it to higher trophic level (i.e. coastal fishes). Moreover, it allows us to think that micro-organisms (diatoms, bacteria and fungi) colonising leaf litter may constitute an important food source for litter fauna. [less ▲]

Detailed reference viewed: 62 (3 ULg)
See detailModernité médiatique et dialogue culturel
Durand, Pascal ULg

Conference (2006, May 25)

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Peer Reviewed
See detailQuelques années après la réforme des polices: un regard sur la formation
Fincoeur, Bertrand ULg

Conference (2006, May 23)

Detailed reference viewed: 6 (3 ULg)
See detailLa censure invisible
Durand, Pascal ULg

Conference (2006, May 19)

Detailed reference viewed: 14 (0 ULg)
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See detailEfficiency of an autobiographical memory remediation therapy in schizophrenia patients
Blairy, Sylvie ULg; Neumann, Aurore; Philippot, Pierre

Conference (2006, May 19)

Detailed reference viewed: 11 (2 ULg)
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See detailK-excess, an unexploited method for discovering red quasars
Nakos, T.; Willis, J.; Andreon, S. et al

Conference (2006, May 19)

Detailed reference viewed: 13 (2 ULg)
See detailDesign of stealth nanoparticles for drug delivery based on new amphiphilic copolymers
Rieger, Jutta ULg; Passirani, Catherine; Dubois, Philippe et al

Conference (2006, May 18)

Detailed reference viewed: 31 (1 ULg)
See detailEfficient controlled radical polymerization of vinyl acetate based on cobast complexes
Debuigne, Antoine ULg; Detrembleur, Christophe ULg; Bryaskova, Rayna et al

Conference (2006, May 18)

Detailed reference viewed: 9 (1 ULg)
See detailAccompagner pour une qualité d'accueil en question
Pirard, Florence ULg

Conference (2006, May 17)

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See detailLes manuels scolaires d'histoire, obstacles à la compréhension "historienne" ?
Jadoulle, Jean-Louis ULg; Bouhon, Mathieu

Conference (2006, May 17)

Detailed reference viewed: 8 (1 ULg)
See detailThéologie et politique dans le Léviathan de Hobbes
Herla, Anne ULg

Conference (2006, May 17)

Detailed reference viewed: 1 (0 ULg)
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See detailUsing the HUBER® technique for the rehabilitation of patients with multiple sclerosis
Maertens de Noordhout, Benoît; Houlmont, F.; Léonard, Yves et al

Conference (2006, May 10)

Detailed reference viewed: 11 (0 ULg)
See detailLe mouvement des paysans sans terre au Brésil
Schoonbroodt, Bénédicte ULg

Conference (2006, May 08)

Detailed reference viewed: 15 (8 ULg)
See detailCoût des infrastructures et durabilité en milieu périurbain
Halleux, Jean-Marie ULg

Conference (2006, May 05)

Detailed reference viewed: 4 (1 ULg)
Peer Reviewed
See detailLa construction de la norme d’employabilité
Orianne, Jean-François ULg

Conference (2006, May 05)

Detailed reference viewed: 33 (3 ULg)
Peer Reviewed
See detailPhysiological role of the putative ammonium transporter RhCG in the mouse
Biver, Sophie ULg; Scohy, Sophie; Szpirer, Josiane et al

Conference (2006, May 05)

Detailed reference viewed: 18 (1 ULg)
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See detailLe larynx cicatriciel: rééducation logopédique
Morsomme, Dominique ULg; Ingrid, Verduyckt

Conference (2006, May 05)

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See detailProblèmes cardiovasculaires : actualisation des connaissances
Krzesinski, Jean-Marie ULg

Conference (2006, May 04)

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See detailVZV IgG and VZV IgM determination: a comparison study.
HUYNEN, Pascale ULg

Conference (2006, May 04)

Detailed reference viewed: 4 (1 ULg)
See detailL'accès du pharmacien à la spécialisation en biologie clinique
Chapelle, Jean-Paul ULg

Conference (2006, May 03)

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See detailThe generalized-alpha time-integration scheme for mechatronic systems with elastic components
Bruls, Olivier ULg

Conference (2006, May)

This talk concerns the numerical simulation of mechatronic systems, such as robots, machine-tools or modern vehicles. In general, a mechatronic system is composed of various technological components: a ... [more ▼]

This talk concerns the numerical simulation of mechatronic systems, such as robots, machine-tools or modern vehicles. In general, a mechatronic system is composed of various technological components: a mechanism, actuators, sensors, and control units. For critical applications, it is also necessary to account for elastic deformations in the mechanism. The generalized-alpha method has been initially developed for the dynamic simulation of flexible mechanical structures, which are represented by lightly damped second-order ODEs. Usually, those equations are obtained after a finite element spatial discretization, with the consequence that they are affected by a large number of high-frequency modes with a purely numerical origin. The generalized-alpha method has very interesting properties in this context, such as an adjustable amount of high-frequency numerical dissipation, A-stability, second-order accuracy, and a high level of computational efficiency. A mechanism with elastic components can be described using the nonlinear finite element formalism. Due to the presence of kinematic constraints, the equations of motion are second-order DAEs, and we shall consider the generalized-alpha method for the direct simulation of the index-3 problem. In particular, some results about the convergence and the stability of the algorithm will be discussed. Finally, a mechatronic system involves mechanical and non-mechanical components, and it is thus modelled as a mixed set of second- and first-order DAEs. We will show that those coupled equations of motion can also be solved in the time domain according to the generalized-alpha scheme. An important problem is then associated with the selection of the parameters of the method. The presentation will be illustrated by academic and non-academic applications, for example in vehicle dynamics and in robotics. [less ▲]

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See detailAu-delà des labels : du management de la RSE au management par la RSE
Delhaye, Christine; El Abboubi, Manal ULg; Xhauflair, Virginie ULg

Conference (2006, May)

Detailed reference viewed: 35 (2 ULg)
See detailDonnées biochimiques, sensorielles et fonctionnelles sur l'huile de noyaux de dattes
Besbes, S.; Blecker, Christophe ULg; Deroanne, C. et al

Conference (2006, May)

Detailed reference viewed: 8 (1 ULg)
Peer Reviewed
See detailContribution to a jaw behavior and deformation study
Mengoni, Marlène ULg; Limme, Michel ULg; Radu, Jean-Pol ULg et al

Conference (2006, May)

Detailed reference viewed: 45 (19 ULg)
See detailEnergy conservation and CO emissions of fuel oil boilers used in domestic heating
Cuevas, Cristian; Ngendakumana, Philippe ULg

Conference (2006, May)

According to the European standard, the CO emissions of new fuel oil boilers, whose output power is lower than 400 kW, are limited in steady-state regime to 110 mg/kWh of energy consumption. In order to ... [more ▼]

According to the European standard, the CO emissions of new fuel oil boilers, whose output power is lower than 400 kW, are limited in steady-state regime to 110 mg/kWh of energy consumption. In order to assess the performance of actual fuel oil boilers, an experimental work has been performed on a boiler available in the laboratory and whose output nominal power is about 370 kW. The two main parameters investigated are the nozzle capacity and the corresponding fuel injection pressure to keep the same burner consumption. Four nozzles whose capacity ranges from 30 to 45 kg/h at 20 bar were fitted on the burner equipping the fuel oil boiler. All the nozzles used are spill return and 45° type. To assess the CO emissions of the fuel oil boiler, tests have been performed in transient and steady-state regimes. The tests were performed so that the output power was kept constant in steady-state regime (same water flow rate and inlet and outlet temperatures). That is why for each nozzle tested, the fuel injection pressure has been adjusted in order to maintain the fuel mass flow rate at around 37.7 kg/h. On the other hand, the oxygen content of the flue gas in the chimney was kept constant (around 3%) by adjusting only the position of the burner air damper (the position of the flame holder was kept constant) and thus the air combustion mass flow rate. Classical gas analysers were used to measure the CO2, O2, CO and NOx concentrations in the flue gas. The tests performed showed that in steady-state regime, the CO emissions are very low compared to the European standard. On the other hand, in the transient regime (start-up regime for a cycling boiler), the CO emissions are not negligible and increase significantly if a high capacity nozzle is fitted on the fuel oil burner. In short, the paper demonstrates that in order to increase the boiler thermal efficiency and thus to reduce CO2 emissions (for the same output power), one has to avoid the CO emissions in the transient regime. When performing a replacement of the burner nozzle, a low capacity nozzle associated with an adjustment of a high fuel injection pressure is recommended, since a reduction of CO emissions in the starting-up regime is achieved and, on the other hand, the thermal efficiency and the pollutants emissions of the fuel oil boiler in steady state regime are not affected. [less ▲]

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See detailNon-confined jet-slot-cavity oscillator: flow-acoustic interaction modeling
Glesser, Martin; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2006, May)

Disturbing whistling due to self-sustained oscillations can be produced in a wide variety of geometries where a sheared subsonic flow impinges on a downstream obstacle. When those self-sustained ... [more ▼]

Disturbing whistling due to self-sustained oscillations can be produced in a wide variety of geometries where a sheared subsonic flow impinges on a downstream obstacle. When those self-sustained oscillations are coupled with an acoustic resonator, the acoustic production can reach dramatically high levels. The configuration known as jet-slot oscillator is studied in the particular case where the resonator is the flow-supply duct and the source region is unconfined. This sound production is due to flow-acoustic interactions and can be modeled by using the vortex-sound theory. It allows one to express the acoustic power generated by the interaction between the acoustic, velocity, and vorticity fields. They are obtained separately by using rather simple models together with experimental input data. The vorticity field is modeled with the assumption that the shear layer is rectilinear and the vorticity is only concentrated on discrete vortex-points convected at constant velocity. The vorticity being non null only in the shear layer, the velocity field is calculated only in this region where it is equal to the vortices convection speed. The source region dimensions being small compared to the acoustic wavelength, this field is considered, in harmonic regime, as a sinusoidal temporal fluctuation of a potential field. This field can be taken as resulting from the flow produced by the radiation of the flow supply duct's acoustic resonance. It is obtained by solving the Poisson equation in a simplified geometry obtained by Schwarz-Christoffel mapping. The configuration studied here presents some specific problems which must be addressed to correctly model its sound production. Experimentations are used to specify the missing parameters. The major one is the synchronisation between the vorticity field and the acoustic field which governs the way that the vortices interact with the resonant acoustic field. At last, comparison between experimental data and modeling results permits to validate the study, in terms of emitted frequency. Further developments of the model will allow to predict the emitted sound level. [less ▲]

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